WO2002073699A2 - Nanofabrication - Google Patents

Nanofabrication Download PDF

Info

Publication number
WO2002073699A2
WO2002073699A2 PCT/US2002/007769 US0207769W WO02073699A2 WO 2002073699 A2 WO2002073699 A2 WO 2002073699A2 US 0207769 W US0207769 W US 0207769W WO 02073699 A2 WO02073699 A2 WO 02073699A2
Authority
WO
WIPO (PCT)
Prior art keywords
nanowires
magnetic
multilayer nanostructure
copolymer
conductive
Prior art date
Application number
PCT/US2002/007769
Other languages
French (fr)
Other versions
WO2002073699A3 (en
WO2002073699A9 (en
Inventor
Mark T. Touminen
Thomas P. Russell
Andrei Ursache
Mustafa Bal
Original Assignee
University Of Massachusetts
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University Of Massachusetts filed Critical University Of Massachusetts
Priority to CA002451882A priority Critical patent/CA2451882A1/en
Priority to KR1020037012051A priority patent/KR100878281B1/en
Priority to EP02725158A priority patent/EP1374310A4/en
Priority to JP2002572644A priority patent/JP2004527905A/en
Publication of WO2002073699A2 publication Critical patent/WO2002073699A2/en
Publication of WO2002073699A3 publication Critical patent/WO2002073699A3/en
Publication of WO2002073699A9 publication Critical patent/WO2002073699A9/en

Links

Classifications

    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/53Electrodes intimately associated with a screen on or from which an image or pattern is formed, picked-up, converted, or stored
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y10/00Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/16Coating processes; Apparatus therefor
    • G03F7/164Coating processes; Apparatus therefor using electric, electrostatic or magnetic means; powder coating
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02Main electrodes
    • H01J1/30Cold cathodes, e.g. field-emissive cathode
    • H01J1/304Field-emissive cathodes
    • H01J1/3048Distributed particle emitters
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/48Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/15Structures with periodic or quasi periodic potential variation, e.g. multiple quantum wells, superlattices
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10KORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K10/00Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having a potential-jump barrier or a surface barrier
    • H10K10/701Organic molecular electronic devices
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/10Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/10Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
    • H10N10/17Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00Galvanomagnetic devices
    • H10N50/01Manufacture or treatment
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00Manufacture or treatment of nanostructures
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00Electrodes common to discharge tubes
    • H01J2201/30Cold cathodes
    • H01J2201/304Field emission cathodes
    • H01J2201/30446Field emission cathodes characterised by the emitter material
    • H01J2201/30453Carbon types
    • H01J2201/30469Carbon nanotubes (CNTs)
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001Technical content checked by a classifier
    • H01L2924/0002Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

  • the invention relates to fabrication of nanoscopic structures, hi particular, the invention relates to functionalized nanoscopic structures on surfaces.
  • FE devices based on carbon nanotube materials are disclosed in "Flat panel display prototype using gated carbon nanotube field emitters," by Wang et al., App. Phys. Lett., 78, (2001) 1294, and can provide acceptable field emission, but can be difficult to fabricate.
  • Serial writing processes can be used to pattern magnetic media, as disclosed in "Writing and reading perpendicular magnetic recording media patterned by a focused ion beam," by Lohau et al., App. Phys. Lett, 78, (2001), 990, and "Magnetic block array for patterned magnetic media” by Koike, et al, App. Phys. Lett, 78, (2001), 784.
  • IBM Almaden Research Center have utilized a fabrication scheme that resulted in patterned media having storage density of 100 Gb/in 2 , as described in Lohau et al. This scheme used a focused Ga + ion beam to cut trenches in granular Co 70 Cr 8 Pt ⁇ 2 film media. These processes tend to be slow, and are not well suited to high throughput manufacture.
  • thermoelectric (TE) cooling devices has not increased significantly during the last 40 years, and currently, the figure-of-merit (ZT) of the best materials is less than one.
  • Semimetal materials such as Bi and Bi 2 Te 3 have the highest ZT values and are currently used in commercial TE devices manufactured by companies such as Marlow and Melcor.
  • the invention provides a method of preparing a laterally patterned array.
  • the method includes coating some of conducting or semiconducting substrate (for example, a metal, such as gold) with a block copolymer film (for example, a block copolymer of methylmethacrylate and styrene), where one component of the copolymer forms nanoscopic cylinders in a matrix of another component of the copolymer; placing a conducting layer on top of the copolymer to form a composite structure; vertically orienting the composite structure; removing some of the first component fi-om some of the structure to form nanoscopic pores in that region of the second component; cross-linking the second component; and at least partially filling some of the nanoscopic pores with a material.
  • a conducting or semiconducting substrate for example, a metal, such as gold
  • a block copolymer film for example, a block copolymer of methylmethacrylate and styrene
  • the substrate can include conducting and non-conducting regions, which can be lithographically patterned.
  • a first component can be removed from some of the structure which is at least partially overlaying a conductmg portion of the substrate.
  • the structure can be vertically oriented by heating with an electric field, for example, for at least one hour.
  • Some of the first component can be removed by exposing some of the structure to ultraviolet radiation, an electron beam, or ozone.
  • Some of the first component can be removed by degrading the component and treating some of the structure with an agent that selectively removes the degraded component.
  • Some of the nanoscopic pores can be filled by electrochemical deposition. Some of the nanoscopic pores and surface of the second component can be wetted with a surfactant prior to filling with material.
  • the invention provides an array manufactured by the methods described herein.
  • the array can include a substrate, a polymer film on the substrate, and at least one set of parallel metallic (for example, gold, copper or nickel) or semi-metallic cylinders in the film, and arranged perpendicular to the substrate.
  • the cylinders can include a magnetic material, such as cobalt or nickel.
  • the magnetic arrays can be used to make a magnetic storage medium, or a magnetoresistance device, or a giant magnetoresistive device.
  • Non-magnetic metals can be used in such arrays to make, for example, a field emission device, hi some embodiments of these arrays, at least one set of cylinders includes n-type material and at least another set of cylinders includes p-type material. Such an array can be used to create a thermoelectric cooler.
  • the cylinders can also include alternating layers of magnetic and non-magnetic material, whether the layers alternate substantially regularly along the length of the cylinders or not. h such arrays, the sets of cylinders can be configured in substantially regular geometrical shapes, such as circles or triangles. Of course, irregular shapes can also find application in the devices disclosed herein.
  • one type of cylinder has a given magnetization direction, and another type has an opposite magentization direction, h some embodiments, at least one set of cylinders is in electrical contact with another set of cylinders, for example, by a conductive contact on top of the film.
  • the term "vertically-oriented," when referring to a copolymer film means a film that has cylindrical pores with the axis of the pores substantially noraial to the surface with which the film is associated, or substantially noraial to the film surface itself.
  • the new materials can have cylindrical pores that are vertically oriented, or oriented at an angle to vertical, as long as the cylinders are oriented in substantially the same direction, e.g., in parallel.
  • These cylinders can have various shapes and can, but need not, have a circular diameter cross-section.
  • the term “nanoscale” refers to a characteristic size range, for example, of arrays, that is attained using the methods of self-assembly of copolymer molecules described herein.
  • the pore diameter, the wire diameter, the wire lengths and the period of the array can be in the nanoscale range, that is, within a range of about a nanometer to over a thousand nanometers.
  • nanowire refers to nanoscale material created in an array pore. The term does not imply that the aspect ratio of the material need be high, and in some embodiments, the material to be deposited in an array can have a low aspect ratio.
  • Nanowires can also refer to material that is not necessarily electrically conductive, but is nevertheless, useful when present in nanoscale arrays.
  • multilevel refers to structures that can be constructed by multiple, independent levels of lithography, with at least one level created with a laterally-patterned diblock copolymer film.
  • multilayering refers to a structural element within a single layer of lithography that contains more than one material.
  • wire refers to conductive material having width and length, where the aspect ratio (that is the ratio of length to width) is at least 2:1. This term is distinguishable from the term “dot,” which refers to conductive material with lower aspect ratios.
  • the techniques and systems described herein include many advantages.
  • the extremely high density of the magnetic cylinders in the new films offers the capability of using this system for next-generation magnetic data storage applications, with potential data storage densities in excess of 1000 Gbit/in2.
  • the well-controlled size and separation distance of the magnetic metals on the metal, e.g., gold, film also offer the means to engineer next-generation giant-magnetoresistance magnetic-field-sensing devices.
  • the processes are parallel, scaleable, and not subject to the speed limitations experienced in nanofabrication techniques based on serial writing.
  • the teclmiques are amenable to manufacture, in that they are simple, fast, and cost-effective. They are readily adoptable by industry and compatible with other fabrication processes.
  • the techniques described herein significantly advance the general utility of nanofabrication by self- assembling copolymer templates.
  • the nanofabrication techniques are amenable to manufacture, in that they are simple, fast, and cost- effective. They are readily adoptable by industry and compatible with other industrial microfabrication processes.
  • lateral patterning offers the capability of using such systems for the manufacture of electronic circuits on chips.
  • the integration of nanostructures within chips and the interfacing of the structures with other chip elements in arbitrary locations is made possible through the methods disclosed herein.
  • these three-dimensional structures offer the means to engineer electronic field-emission arrays.
  • the arrays can be used in flat panel displays that are brighter, higher-resolution, less expensive, thim er, and more flexible than those currently available.
  • Other field emission electron devices are possible, such as transistor-like devices, spin-polarized electron emitters, and other l ⁇ iown devices based on field emission.
  • the three-dimensional structures also offer the means to engineer solid-state thermoelectric cooling devices, including those with multistage cooling.
  • Other applications include magnetoresistive sensors, high-capacity magnetic data storage, smart media, spiiitronics, chemical-sensing devices, biomoleciilar diagnostic sensor arrays, designer "micromagnetic” media, and molecular electronics, for example.
  • Fig. 1 is a schematic diagram of an exposure process that can be used to create a nanoporous array, and subsequently can be used to create an array of nanowires.
  • Fig. 2a is a side view schematic diagram of a selective exposure process that can be used to create a laterally patterned diblock copolymer film.
  • Fig. 2b is an overhead view schematic diagram of a selective exposure process that can be used to create a laterally patterned diblock copolymer film, in this case, a triangle pattern.
  • Fig. 3 is a schematic diagram of a selective exposure process that can be used to create a laterally patterned diblock copolymer film, and subsequently can be used to create a laterally patterned nano structure, in this case, a triangle shaped nanostructure.
  • Fig. 4 is a perspective view schematic diagram of a multilevel nanostructure created from laterally patterned diblock copolymer film.
  • Fig. 5 is an overhead view schematic diagram of a multilevel nanostructure created from laterally patterned diblock copolymer film.
  • Fig. 6 is a perspective view schematic diagram of a field emission array created from laterally patterned diblock copolymer film, including two sets of nanowires.
  • Fig. 7 is an overhead view schematic diagram of a field emission array created from laterally patterned diblock copolymer film, including four individually- addressable sets of nanowires.
  • Fig. 8a is an overhead view optical image (at 5X) of a sample showing an electrode pattern with a vertically-oriented diblock copolymer film covering the surface.
  • Fig. 8b is an overhead view optical image (at 5X) of the sample from Fig. 8a after electron beam patterning and removal of a copolymer component to form nanopores.
  • Fig. 8c is an overhead view optical image (at 5X) of the sample from Fig. 8b after nanowires are electrodeposited on the sample.
  • Fig. 8d is a closeup overhead view optical image (at 5X) of the sample from
  • Fig. 9 is a perspective view schematic diagram of a single-stage thermoelectric cooler created from laterally patterned diblock copolymer film.
  • Fig. 10 is a perspective view schematic diagram of a four- wire, giant magnetoresistive (GMR) device created from laterally patterned diblock copolymer film.
  • GMR giant magnetoresistive
  • Fig. 11a is an overhead view optical image (at 10X) of a four-wire magnetoresistive device created from laterally patterned diblock copolymer film before nanowire electrodeposition.
  • Fig. 1 lb is an overhead view optical image (at 10X) of a four- wire magnetoresistive device created from laterally patterned diblock copolymer film after nanowire electrodeposition.
  • Fig. 12a is a graph of giant magnetoresistance measurements of a four- wire device as depicted in Fig. ' 1 lb, as a function of device temperature.
  • Fig. 12b is a scanning electron micrograph SEM image of vertically oriented nanowires created from laterally patterned diblock copolymer film.
  • Fig. 13 a is a side view schematic diagram of a particular configuration of a magneto-electronic transport nanodevice created from laterally patterned diblock copolymer film, where the "current in” and “current out” electrodes are both on the substrate level.
  • Fig. 13b is a perspective view schematic diagram of a further particular configuration of a magneto-electronic transport nanodevice created from laterally patterned diblock copolymer film, where the "current in” electrode is on the substrate level, and the “current out” electrode is on an upper interconnect level.
  • Fig. 13c is a side view schematic diagram of three distinct types of magneto- electronic nanoelements used in the devices of Figs. 13a and 13b.
  • Fig. 14a is an overhead view schematic diagram of a particular example of patterned media, showing patterned perpendicular media.
  • Fig. 14b is an overhead view schematic diagram of a further particular example of patterned media, showing customized patterned perpendicular media.
  • Fig. 15a-e is a schematic depiction of a method of interfacing metal electrodes with the button and top of nanostructures made by a nanoscale diblock copolymer template.
  • Figs. 16a-c is a series of graphs of magnetoresistance measurements for the device depicted in Fig. 1 lb, taken a various magnetic field orientations.
  • Fig. 17 is a microscope photograph of a device constructed as shown in Fig. 13.
  • Fig. 18 is a graph of magnetoresistance measurement of electron transport through the device shown in Fig. 17.
  • Fig. 19 is a microscope photograph of a field emission test sample from a device constructed as depicted in Fig. 6.
  • Fig. 20 is a graph of electronic field emission measurements made from an array of cobalt wires in vacuum, from the device shown in Fig. 19.
  • Fig. 21 is a microscope photograph of particular field emission test samples from Fig. 19, but magnified to 50x.
  • Fig. 22 is a plot of normalized MR response (%) at 0 field versus temperature, in the perpendicular orientation.
  • Described herein is a process technology for the fabrication of three- dimensional devices using laterally-patterned block copolymer templates.
  • copolymer films are patterned laterally by selective-area exposure to radiation sources.
  • This produces a multi-scale lithographic template, that is, a regular array of nanoscale pores with an overall lateral extent confined to an arbitrary and desired design.
  • the dimensions of the lateral design can range from the nanoscale to the microscale.
  • the patterned array template is combined with appropriately tailored pre- and post- fabrication steps to produce multilevel, three-dimensional integrated nanoscale media, devices, and systems.
  • the method introduces the ability to integrate nanoscale functional elements in arbitrary and desired locations on a chip and to integrate the functional elements with other chip components in a practical manner.
  • the general utility of self-assembled copolymer templates is thereby significantly advanced.
  • diblock copolymers comprised of two chemically distinct polymers covalently linked end-to-end, can be self-assembled into well- ordered arrays of spheres, cylinders or lamellae, depending on the volume fraction of the components comprising the polymer chain.
  • Directed self assembly carried out with an external field (for example an electric or magnetic field, or a temperature or concentration gradient), can result in useful films, with orientation sufficiently long- ranged to allow the production of extended arrays of nanowires having aspect ratios of at least 2:1 or 3 : 1.
  • an external field for example an electric or magnetic field, or a temperature or concentration gradient
  • a 70/30 (by volume fraction) polystyrene-polymethylmethacrylate diblock copolymer can be exemplified.
  • Other cylinder constituents of the copolymer can be, for example, polybutadienes, polycaprolactones, and other materials that can be solubilized in solvents.
  • Other matrix constituents can include polybutadienes and other materials which are not reactive with agents used to remove the cylinder constituents.
  • a block copolymer is first deposited, e.g., spun-cast from solution onto a substrate, such as a metallic, semiconducting, or insulating substrate.
  • the substrate can be rigid or flexible.
  • substrates at least partially coated with a thin film of metal include: silicon, such as silicon wafers or chips; and polymeric substrates, such as Kapon, each of which can be made conducting or semiconducting by coating at least a portion of the substrate surface with a conductmg or semiconducting material.
  • the oxidation of the metal should not be as rapid as the deposition rate of materials to be deposited.
  • substrates for use in the devices and techniques described herein may be a coating or a non-continuous surface layer on an underlying material that need not be conducting.
  • the amount of substrate used can be any amount that allows the substrate to function as an electrode, when electrodeposition is used to deposit functional material. If other methods of material deposition are employed, the nature and amount of substrate is not limited.
  • the substrate in embodiments in which it is present as a coating or surface layer, can be applied to an underlying substrate by conventional lithographic techniques, or other l ⁇ iown methods of depositing conducting materials on surfaces.
  • the substrate can include metals, for example, gold.
  • the substrate can have gold coated or deposited on an underlying material.
  • the substrate can be a semi-metal oxide, including for example, silicon oxide. Particular preparation methods are not required, although in some embodiments, washing the substrate with water, followed by rinsing with mild acid and/or base can be carried out.
  • Diblock copolymers comprised of two chemically distinct polymers covalently linked end-to-end, can be self-assembled into well-ordered arrays of spheres, cylinders or lamellae, depending on the volume fraction of the components comprising the polymer chain. If the volume fraction of a major component is about 0.7 (e.g., from about 0.65 to about 0.80), any copolymer will self-assemble into a hexagonal array of cylinders of the minor component embedded in a matrix of the major component.
  • the mole ratio of the minor component of the diblock copolymer can range from about 0.20 to about 0.35 to permit the formation of microphases such as will result in cylinder formation. If the volume fraction of the major component is about 0.9, the minor component will form spheres, which can be elongated into very thin cylinders when an orienting field, e.g., an electric field, is applied.
  • an orienting field e.g., an electric field
  • a mixture of diblock copolymers can be used to create cylinders of different types, for example B and C cylinders.
  • Higher block copolymers, such as A-B-C triblock copolymers can also be used.
  • the molecular weight of the copolymer can be varied to achieve differing cylinder diameters. For example, a molecular weight copolymer in the range of about 1.5 million molecular weight units (Daltons) can result in a cylinder diameter of about 70 nm. A molecular weight in the range of about 20,000 Daltons can result in a cylinder diameter of about 14 nm. A molecular weight of about 4 million Daltons results in cylinders with a diameter of about 100 nm, while a molecular weight of about 15 kilodaltons results in a diameter of about 1.0 nm.
  • Daltons molecular weight units
  • a molecular weight in the range of about 20,000 Daltons can result in a cylinder diameter of about 14 nm.
  • a block copolymer including a component that can be crosslinked is desirable.
  • This component can be crosslinked before or during removal of another component, and can therefore add structural integrity to the copolymer.
  • This component can be referred to as the matrix component, hi some embodiments, the matrix component will be the major component of a copolymer, by volume. Suitable matrix components include polystyrene, polybutadiene, polydimethylsiloxane, and other polymers.
  • the component that is to be removed can be called the core component, hi some embodiments, the core component will be a minor component of a copolymer, by volume.
  • Suitable core components include polymethylmethacrylate, polybutadiene, polycaprolactone or a photoresist.
  • core components are materials that can be degraded or decomposed differentially than the matrix material.
  • block copolymers of styrene and methylmethacrylate can be used.
  • the methylmethacrylate block constitutes a minor component.
  • a 70/30 (by volume) diblock copolymer of polystyrene/polymethylmethacrylate can be employed.
  • any block copolymers can be used, such as alkyl/alkyl, alkyl/aryl, aryl/aryl, hydrophilic/hydrophilic, hydrophilic/hydrophobic, hydrophobic/hydrophobic, positively or negatively charged/positively or negatively charged, uncharged/positively or negatively charged, or uncharged/uncharged.
  • the film thickness can vary as desired, for example, from about 0.5 nm to about 10 cm, or from about 1 nm to about 1 cm, or fi-om about 5 nm to about 1000 nm. hi some preferred embodiments, film thicknesses can vary from between about 10 nm to about 200 microns, or from about 1 micron to 200 microns, or up to about 25 mil.
  • Orientation of the copolymers can be carried out using directed self-assembly, that is, self-assembly which is directed by an external field, for example an electric field, a magnetic field, a thermal gradient or a concentration gradient.
  • an external field for example an electric field, a magnetic field, a thermal gradient or a concentration gradient.
  • Vertical orientation of the cylinders can be accomplished by, for example, electric field alignment under annealing conditions, or, for example, self-orientation using controlled interfacial conditions.
  • the different chemical constitutions of the blocks of the copolymer can result in a difference in the dielectric constants of the copolymer domains.
  • a difference of about 0.1% in the dielectric constants can result in a specific, e.g., vertical, orientation, h an electric field
  • the orientation dependent polarization energy associated with the cylinders, dielectric bodies that are anisotropic in shape will align the cylinders in parallel to the electric field lines, for example, as described in Morkved, et al., "Local control of microdomain orientation in diblock copolymer thin films with electric fields," Science, 273, (1996), 931; Thurn-Albrecht, et al., "Overcoming Interfacial Interactions with Electric Fields," Macromolecules, 33, (2000) 3250-53; Amundson, et al., "Alignment of lamellar block-copolymer microstructure in an electric-field.
  • any surface induced alignment of the morphology can be overcome, producing cylindrical microdomains oriented in parallel with the fields, which can be normal to the substrate, that extend completely through a one-micron-thick sample.
  • Scattering experiments are an easy means to characterize the orientation of the microphase structure in a thin film.
  • a cylindrical structure oriented noraial to the substrate is laterally periodic. Consequently, the scattering pattern measured at a finite incidence angle is strongly anisotropic, consisting of two equatorial Bragg peaks.
  • a removable conducting layer is placed on top of the copolymer film, sandwiching the film between two electrodes.
  • a conducting layer can be deposited by spin coating and then, after annealing, be removed by etching, e.g., by solvent chemical, or physical etching.
  • etching e.g., by solvent chemical, or physical etching.
  • a "spin-on" sacrificial layer can be applied, followed by a metal layer that is evaporated, sputtered, or spun-on. After annealing, the sacrificial layer can be removed by solvent, chemical, or physical etching.
  • This conducting layer can be metal, or semiconducting material, and can optionally be in contact with the entire film surface. For example, aluminum, copper, gold or other metal can be used as the conducting layer on the copolymer film.
  • Metallized layers such as aluminized KAPTON® can also be used. Metallized layers can promote the formation of a uniform film surface as orientation, e.g., vertical orientation, is carried out.
  • orientation e.g., vertical orientation
  • Aluminized Kapton® is a layer of aluminum in register with a layer of Kapton®, in which the Kapton® layer is directly in contact with the copolymer film. The Kapton® layer must not be so thick as to interfere with an electric field established between the aluminum layer and the substrate on the other side of the film.
  • Other metals and other polymeric materials can be used to create metallized layers for electric field-induced vertical orientation.
  • the sandwich structure can be heated above the glass transition temperature of the copolymer. Voltage is then applied between the substrate and the conducting layer to create an electric field through the mobilized copolymer film.
  • the electric field strengths are at least 5 V/mm, for example, at least 10 V/mm.
  • the copolymer film assembly After holding the film in this state for a sufficient time to allow the copolymers to self-assemble, for example, over 30 minutes, over 60 minutes, over 1.5, over 2, or over 3 hours, the copolymer film assembly is cooled to a temperature below the glass transition temperature of the copolymer.
  • the orienting field e.g., electric field, is desirably turned off after the cooling has taken place.
  • the conducting layer, and any associated additional layer is removed from the polymer film.
  • the film now includes an ordered array of cylinders of one copolymer component embedded in a matrix of another copolymer component.
  • Self-assembly results in parallel orientation of the blocks, such that one component forms cylinders with the cylinder axis substantially in parallel to each other, e.g., all normal to the surface of the substrate, or substantially normal to the film surface itself.
  • the cylinders desirably extend substantially from the substrate surface to the surface of the film.
  • the cylinders have diameters ranging from about 5 nm to about 100 nm.
  • the periodicity (L) of the cylindrical domains in the film is the distance between the central axes of the cylinders, and is proportional to the molecular weight of the copolymer (to the 2/3 power).
  • the periodicity defines the diameter of the cylinders. Periodicity can range, for example, from about 1.0 to about 70 nm, but can be outside this range.
  • methods other than heating are used to make the molecules of the copolymer mobile. For example, rather than heating the copolymer to its glass transition temperature, one can, in effect, lower the glass transition temperature, by any of a number of ways. For example, one can add a plasticizer, a solvent, or a supercritical fluid, such as supercritical CO 2 , to the copolymer to mobilize the molecules and allow them to move and self-assemble.
  • Nanowire aspect ratios can range, for example, from about 0.05:1 to about 10,000:1; or about 0.1 :1 to about 5,000:1; or about 1:1 to about 500:1; or about 2:1 to about 10,000:1 or about 2:1 to about 5,000:1, or about 2:1 to about 500:1,- or about 2:1 to about 100:1.
  • Such large aspect ratio wires in an extended array are useful for creating sufficiently large magnetic coercivity though shape anisotropy, for example.
  • Orientation using controlled interfacial interaction is well suited for relatively thin diblock films. For example, less than about lOOnm, or less than about 60nm, or less than about 40nm thick.
  • a substrate is pre-treated so that it presents a "neutral" surface to a copolymer diblock film.
  • Hydrogen-passivated silicon, or silicon coated with a random-copolymer brash are suitable exemplary neutral surfaces.
  • Thin diblock films can be spun-cast atop this surface and annealed. The cylinders will self-orient vertically without directed self assembly from an external field in sufficiently thin diblock films, for example, films of less than about lOOnm.
  • Ultra-high density magnetic data storage can be achieved if magnetic materials having larger intrinsic anisotropies than cobalt are used. (FePt for example.) High pattern resolution on thin films is possible using an electron beam for lateral patterning.
  • the surface of the copolymer film obtained after orientation can be used as formed for a number of applications.
  • the surface of the vertically oriented copolymer film is desirably substantially smooth.
  • Such arrays and techniques for producing substantially flat surfaces are described in United States Provisional Patent Application Serial No. 60/191,340, filed March 22, 2000, titled
  • Magnetic Arrays For magnetic data storage applications, in which a reading device passes rapidly over a magnetic array, the surface is desirably smooth. Any application in which a read or write head passes over an array can require high smoothness. Smoothness of a magnetic array for data storage and retrieval applications desirably ranges from about 0.5 to about 5.0 nm.
  • the surfaces of vertically oriented copolymer films can be made smooth with the use of an additional material, such as an elastomer or a crosslinked elastomer applied to the conducting layer before vertical orientation steps are undertaken.
  • an additional material such as a crosslinked silicone, including crosslin ed- polydialkylsiloxanes, -polydiarylsiloxanes, or -polyalkyl-arylsiloxanes, including, for example, crosslinked-polydimethylsiloxane
  • a conducting layer or in some embodiments, to an additional layer, as described above.
  • the conducting layer, and/or any associated additional layer is coated with the additional elastomeric material, and the layers placed in contact with the copolymer film.
  • Vertical orientation is carried out, as described above, and the layers removed from the surface of the vertically oriented copolymer film. The surface can be made thereby smoother than surfaces created without the additional elastomeric material.
  • the minor component (or in some embodiments the major component) of the substrate-associated copolymer is removed (either component of a diblock copolymer can be "minor” or “major,” and the components can also be equally present). Removal of the minor component is achieved, e.g., by exposure to radiation (ultraviolet light, x-ray radiation, gamma radiation, visible light, heat, or an electron beam or any other radiation source which selectively degrades the minor component). Degradation or decomposing agents such as reactive oxygen species, including for example, ozone, or solvents such as ethanol, can also be used. Ultraviolet light can be used to degrade, for example, polymethylmethacrylate as a core component. Ethanol can be used to degrade, for example, polybutadiene.
  • a step to remove any residual component can include treatment with a liquid, including washing with a solvent, or a material that reacts preferentially with the residual component, such as an acid or a base, hi some embodiments, the material used to react with residual degraded component can be, for example, a dilute form of acetic acid.
  • the volume formerly filled by a now removed copolymer component now comprises cylindrical spaces extending through the thickness of the film. The remaining volume is occupied by the remainder copolymer component and is referred to as the matrix.
  • Cross-linking of a component that is not degraded by an energy source or agent can add structural strength to the film, h some embodiments, a copolymer component is crosslinked simultaneously with the degradation of another copolymer component.
  • the radiation can optionally and desirably crosslink and substantially immobilize the matrix component of the diblock copolymer, so that the matrix maintains the array structure even after the cylindrical voids are created.
  • a nanoporous array template is the resulting overall structure.
  • the pore diameters can range from about 5 nm to about 100 nm or more, and the periodicity can range from about 5.0 to 70 nm.
  • the resulting pores are at least partially filled with, for example, metallic, metalloid, semiconductor, and/or magnetic materials.
  • Deposition of functional material can be carried out by, for example, electrodeposition, chemical vapor deposition, electroless deposition, surface chemistry, chemical adsorption, and chemically driven layer-by-layer deposition.
  • electrodeposition is a desirable method, since it provides a driving force for the deposition of material into the bottoms of the pores.
  • electrodeposition within the pores of a nanoscale template derived from films of diblock copolymers provides a convenient means of filling the large aspect-ratio pores in a highly controlled manner to provide an array of nanowires.
  • the nanowires include at least some magnetic material.
  • Magnetic materials include cobalt, nickel, iron, and alloys which contain one or more of these materials, and includes those materials which are measurably magnetic.
  • the nanowires include at least some magnetic material.
  • Magnetic materials are those materials that are measurably magnetic, and can include magnetic metals, such as cobalt, nickel, iron, rare-earth magnetic materials, and alloys that contain one or more of these materials (such as iron-platinum alloys, or PERMALLOY®, an alloy of iron and nickel, with a stoichiometry of Ni 8 ⁇ Fe ⁇ 9 ), as well as magnetic non-metals, including ceramic materials such as strontium or barium in combination with iron oxide.
  • Organic magnets such as tetracyanoethyleiie, can also be employed as magnetic materials.
  • Magnetic systems can also contain materials that are non-magnetic, including nonmagnetic metals, such as copper, gold, silver, and the like.
  • Magnetic materials can also be prepared as magnetic nanowires by deposition of alternating layers of magnetic metals and non-magnetic materials.
  • Such alternating layers can be optionally and, for some embodiments desirably, regularly alternating, and the regularity can include regularly alternating amounts of such materials.
  • a magnetic nanowire can include at least three layers of material alternating as: magnetic metal, non-magnetic material, magnetic metal; or non-magnetic material, magnetic metal, non-magnetic material.
  • the alternating layers can be optionally, and in some embodiments desirably, non-regularly alternating.
  • Magnetic Multilayers and Giant Magnetoresistance Fundamentals and Industrial Applications (Springer Series in Surface Sciences, No 37),” Uwe Hartmann (editor), 370 pages, (Springer- Verlag, 2000), which is incorporated herein by reference.
  • Cobalt/copper alternating multilayers have been found to be useful.
  • Magnetic materials can be generally chosen to have a selected magnetic coercivity, which will depend on the desired application. For example, by using just cobalt (Co) nanowires, the coercivity can range from about 7000 Oe, to any lower number.
  • the perpendicular coercivity of a cobalt nanowire array can exceed 1.7 kOe at 300K, due to the cylindrical shape anisotropy and nanowires having diameters smaller than the size of a single magnetic domain.
  • the coercivity can be tuned to smaller values by selecting specific electrodeposition conditions, pore diameter, and additives. For example, using the techniques described herein (applied field perpendicular to the substrate and parallel to wire axis), one can establish perpendicular coercivity of about 800 Oe at room temperature. Higher coercivities can be obtained by depositing rare earth magnetic materials.
  • Magnetic materials can also have their magnetoresistive behavior tuned by adjusting the thickness of the magnetic sections, the thickness of the noraial metal sections, and the diameter of the multilayered nanowires. These devices are so-called “giant” magnetoresistive devices, which are sensitive magnetic field sensors, in that the resistance changes dramatically with a change in magnetic field.
  • a spin-polarized electron current leaves the larger magnetic region and is injected into the smaller magnet. This current exerts a torque on the magnetization in the smaller magnet and can reverse the direction of magnetization.
  • the change in magnetization is typically accompanied by a discrete change in measured resistance. This results in a way to "write and read” using current.
  • any other material which can be electrodeposited can be employed, including metals generally, semi-metals (including, for example, Bi and BiTe), and certain semiconducting materials that can be electrodeposited.
  • Optimal electrodeposition of magnetic material can involve the alignment of the magnetic axis of the material substantially, parallel or skew noraial to the surface upon which the magnetic material is deposited.
  • Fig. 1 shows an oriented diblock copolymer film on a substrate.
  • the dark areas on the substrate represent one of the components of the diblock copolymer, and the adjacent lighter areas represent the other component of the diblock copolymer.
  • the upper surface of the copolymer film is here shown perfectly flat.
  • the matrix material is desirably removed from the substrate surface after deposition of functional material.
  • the matrix material is desirably present subsequent to deposition to provide structural stability to the array of nanowires, or to allow further post-fabrication lithographic steps. Removal of matrix material can be achieved by treating the array with an agent that selectively degrades the matrix material with respect to the nanowires as described above.
  • the methods of certain embodiments described herein are based on the selective exposure of the diblock copolymer template to a radiation source which removes material fi-om the polymer film, to create three-dimensional nanoscale elements in a multilevel integrative technology.
  • Special multilevel processing steps specifically tailored to each particular device configuration, are used to achieve the complex integration.
  • a simple product may require patterned diblock level of lithography only, while a complex integrated product may also require pre- and post- fabrication lithographic steps.
  • the common technique to all cases of nanostructure fabrication is the selective copolymer patterning technique.
  • the process involves the selective alteration of specific areas or location of a nanoporous copolymer template, e.g., by exposure to a radiation source.
  • Suitable radiation sources for the selective degradation of a copolymer component include, for example, ultraviolet (UV) light, electron beams, or other sources of radiation that can efficiently degrade a component of a diblock copolymer.
  • UV ultraviolet
  • Fig. 2a shows a side view of a vertically oriented diblock copolymer film on a surface, with radiation impinging on the copolymer film. The radiation removes material from the film to create cylinders, and since the exposure is selective, there are areas of the film that contain cylinders, and areas which do not.
  • Fig. 2a shows a side view of a vertically oriented diblock copolymer film on a surface, with radiation impinging on the copolymer film. The radiation removes material from the film to create cylinders, and since the exposure is selective, there are areas of the film that
  • FIG. 2b is an overhead view of the same film, showing explicitly that, in this case, a triangular shape has been imposed on the film surface, resulting in an area where electrodeposition can potentially be carried out, depending on the characteristics of the underlying surface.
  • Fig. 3 depicts the same process and resulting template, with the matrix component of the film deleted in Fig. 3 for clarity.
  • a UV mask or UV projection can be used for spatial selectivity across the surface of the array.
  • a focused electron beam writer or other electron beam source can be used for spatial selectivity.
  • the exposure pattern imposed on the surface can be related to, or dictated by, underlying features in the film or on an underlying surface, or can be unrelated to such features.
  • the underlying surface includes an electrode pattern
  • specific alignment of portions of the diblock exposure pattern with portions of the electrode pattern can be a requirement for device manufacture.
  • the resulting array is referred to as being laterally patterned.
  • surface-selective materials deposition methods can be used to locate desired materials into the pores to create nanoscale elements. Nanowires will be present only in areas which are the union of areas exposed to radiation, and areas containing an electrode underlying the surface of the copolymer film.
  • Novel use of electrochemical deposition methods enables several applications.
  • Other surface-selective materials deposition techniques can be used, including chemical vapor deposition, electroless deposition, surface chemistry, chemical adsorption, and chemically driven layer-by-layer deposition, for example.
  • different electrodes can be held at differing voltages during the electrochemical deposition to allow or prevent deposition at chosen electrodes, and this technique can be referred to as "programmed deposition.”
  • one electrode or group of electrodes
  • This method offers expanded materials versatility, in that different types of nanowires can be deposited on the same chip.
  • Fig. 4 is a schematic diagram of a multilevel structure created using the concepts described above.
  • the substrate includes thin film electrodes in, or on, its surface, which can be created by conventional lithography, for example. Lateral patterning can be carried out in registry with the underlying electrode pattern as desired, followed by electrodeposition of a first material, results in the creation of first nanowires, as shown. Subsequent electrodeposition of a second material, at an electrode potential different from that used for the electrodeposition of the first material results in the creation of second nanowires, as shown.
  • First and second materials can differ in characteristics, particularly in characteristics which are relevant to the functional aspects of the devices.
  • the first and second materials can be metals or semi-metals, so that characteristics, such as reduction potential, semi-metal type (for example, "n"- or "p"-type semi-metal, metalloid or semiconducting materials), reduction potential, and other useful characteristics can be varied in different locations of the film.
  • lateral patterning followed by electrodeposition of a first material creates first nanowires as shown.
  • Another lateral patterning step in a different location, followed by electrodeposition of a second material, at any electrode potential, results in the creation of second nanowires.
  • Fig. 5 shows an overhead view of another example of such a three dimensional structure, emphasizing the relationship between electrical connections underlying (level #1), through (level #2), and overlying (level #3) the matrix component of the diblock copolymer to create electrical connections in registry with components on these differing levels. '
  • Figs. 13 a, and 13b show two basic configurations of magneto- electronic transport nanodevices.
  • Figs. 13a and 13b depict magneto-electronic device configurations that utilize transport current through the nanowires.
  • These devices utilize anisotropic magnetoresistance, giant magnetoresistance, or spin-polarized current switching magnetoresistance, as discussed in Katine et al., "Current-driven magnetization reversal and spin-wave excitations in Co/Cu/Co pillars," Phys. Rev. Lett, 84 > (2000), 3149, for magnetic sensing and "spintronic" purposes.
  • Fig. 13a shows a first configuration, in which the "current in” and “current out” electrodes are on the substrate level, and the interconnection between these two electrodes is on the upper interconnect level.
  • Fig. 13b shows a second configuration, in which the "current in” electrode is on the substrate level and the “current out” electrode is on the upper interconnect level.
  • Particular combinations of these configurations will be readily apparent to those designing circuits.
  • a device of the construction depicted in Fig. 13 has been made, and a microscope photograph of this device is shown in Fig. 17. The patterned black regions are the locations of the nanowires. Magnetoresistance measurements of electron transport through the device depicted in Fig.
  • the nanowires themselves can be multilayered, using pulsed electrodeposition in a two-component bath, for example, to create Cu/Co multilayers, or by sequential electrodeposition.
  • Some embodiments of multilayered nanowires are depicted in Fig. 13c.
  • Magnetic nanowires are, as discussed above, created using magnetic materials, principally including cobalt, nickel, iron, and alloys containing these metals, and are useful for anisotropic magnetoresistance applications.
  • Multilayered magnetic nanowires are created using substantially regularly alternating layers of magnetic materials and non-magnetic materials within individual nanowires (for example, Co/Cu alternating layers), and are useful for giant magnetoresistance applications.
  • Asmmetric magnetic heterostructures are made using substantially nonregularly alternating layers of magnetic and non-magnetic materials, useful for spin-polarized current switching magnetoresistance.
  • the polymer film contains polymer in three distinct states: 1) the degradation by-products; 2) the insoluble component; and 3) the virgin, oriented diblock copolymer in the unexposed regions.
  • the coexistence of these three states offers additional fabrication versatility.
  • solvent or radiation one can choose to remove only the exposed cylinders, or alternatively, the exposed cylinders and the unexposed regions of diblock copolymer.
  • acetic acid can be used to remove degraded polymer fragments from the exposed area, but will not affect the matrix component.
  • An agent such as acetic acid will also not remove material from the virgin, unexposed diblock copolymer.
  • the removal of material from virgin regions can be achieved by treatment with another agent, for example, toluene.
  • the removal of the unexposed diblock copolymer can be chosen to occur at a separate stage of processing, for example, after nanowires have been fabricated in the pores.
  • All individual nanowires within a given set of nanowires have the same magnetization direction, either up or down, corresponding to a data bit of either "1" or "0.”
  • the laterally patterned arrays described herein are of utility.
  • the magnetization switching field of a magnetic nanowire can be modified substantially by the magnetic dipolar interactions it experiences due to neighboring nanowires, and consequently depends on whether the nanowire is found in a circle, triangle, cross- or star-shape, or other shape which tends to maximize or minimize the exposure of nanowires to each other or non-magnetic areas of the film.
  • the lateral extent and shape of an array of magnetic nanowires will influence its switching behavior dramatically.
  • the three dimensional nanostnictured arrays described herein can be used in of technologies, including: display technology, cooling technology, magneto- electronic technology, data storage technology, sensor technology, biomoleciilar array technology, molecular electronic technology, waveguide technology, and other technologies.
  • display technology including: display technology, cooling technology, magneto- electronic technology, data storage technology, sensor technology, biomoleciilar array technology, molecular electronic technology, waveguide technology, and other technologies.
  • the techniques presented here are general and provide advances to a variety of research materials systems.
  • Field emission displays offer high brightness, low power consumption, and flat-panel design.
  • the displays can include an addressable array of field emitters and a phosphorescent screen.
  • Efficient field emission displays require high-aspect-ratio nanoscale metal tips (for example, from about 20:1, or about 35:1, or about 50:1 to about 10,000:1) to enable electronic field emission at low tlireshold voltages.
  • the emitters are desirably arranged into a high-density array.
  • the array is desirably patterned laterally into sets of nanowires, with each pixel electronically addressable. These sets can include from one to 10, 20, 30, or more nanowires, depending on the desired application.
  • the present invention offers simplified processing and the ability to make tip arrays with improved orientation.
  • the ultra-high density, laterally patterned arrays created by the methods described herein can be successfully used for high-resolution, low power, thin and flexible display devices.
  • the high aspect ratio of nanowires created by the techniques described herein allow the tlireshold voltage for emission to be sufficiently low so that power consumption for such field emission devices is correspondingly lowered.
  • the devices are useful for television and video screens, computer monitor screen, and many other display devices such as on watches, GPS devices, and any other devices currently using LED or LCD displays .
  • the thinness of such field emission arrays allows the design of such devices to be far thinner than devices available currently. Display devices made with the technology described herein are also much brighter for a given level of energy consumption than those currently available.
  • the possibility of using a flexible substrate further expands the utility of display devices made with the techniques described herein. Differing display applications will have differing priorities as regards operating characteristics; for example, an outdoor display can require high brightness, and a video display can require high resolution.
  • Fig. 6 is a perspective view of a diagram of such an array.
  • the substrate has electrodes in or on its surface, created by conventional lithography.
  • Diblock copolymer is deposited on the substrate, as described above, for example, by spin-bonding.
  • Vertical orientation, selective irradiation, chemical treatment, and electrodeposition follow to create sets of nanowires, in this case, deposited on two distinct electrodes.
  • the ends of the nanowires are desirably at or near the film surface.
  • FIG. 19 A device according to the construction of Fig. 6 was made, and microscope photographs of this device are shown in Fig. 19.
  • the diblock template is shown patterned into a circular region at 20x magnification in the upper left of Fig. 19.
  • the same region is shown after 250 nm cobalt nanowires have been grown at -IV into the circular region, but before electrical measurements were made at 20x magnification in the upper right of Fig. 19.
  • the same region is shown after electrical measurements were made and then having brought up the emission current to the point at which the sample was destroyed in the lower part of Fig. 19 (lower left at 5x magnification, lower right at 20x magnification).
  • Fig. 20 shows a graph of electronic field emission measurements made from the array shown in Fig. 19. A large current density and a low tlireshold was achieved.
  • Fig. 21 is a close up of the images from Fig. 19, upper right and lower left, before and after destroying the sample, respectively.
  • the electrodes are individually addressable, in this case, with voltages Vi and V 2 . These applied voltages are independently varied as desired to control (that is, turn “on” and “off) the emission current from each nanowire set.
  • a phosphor screen can be placed above the nanowire sets to create a display.
  • Fig. 7 shows an overhead view of a similar device, but with four individually addressable sets of nanowires. It is important to note that nanowires are deposited only on the substrate where: 1) the copolymer is exposed to irradiation that degrades a component of the copolymer down to the substrate surface; 2) the residue of degraded component is removed from the substrate surface; and 3) the substrate surface has an electrical contact allowing electrodeposition.
  • Solid-state cooling devices can also be designed utilizing the technology described herein. At present, the best commercially available theraioelectric cooling devices have theraioelectric figures of merit of approximately 0.1.
  • the techniques described herein can produce devices which have thermoelectric figures of merit approaching or exceeding 2.0, e.g., devices having a figure of unit of 0.5, 0.7, 0.9, 1.0, 1.2, 1.5, 1.7, 1.8, 1.11, 2.0 or greater.
  • Fig. 9 is a diagram of a single-stage thermoelectric cooler which can be made according to the methods described herein.
  • the substrate has electrodes pre-pattemed in or on its surface.
  • a patterned diblock copolymer layer is created on the substrate, as described herein. Again, the matrix component of the copolymer is deleted in Fig.
  • Nanowires of two types are deposited by programmed electrodeposition.
  • “n-type” nanowires, made from “n-type” materials, well l ⁇ iown in the art, are deposited at one electrode
  • “p-type” nanowires, made from “p-type” materials, also well known in the art are deposited at another electrode.
  • a top-layer metal interconnect is then deposited electrochemically.
  • the device operates through the application of current through the device, so that the top plate becomes cold and the electrodes and substrate become warm.
  • the top plate can be used as a heat sink for use in electronic devices, for example.
  • Multistage coolers can also be made by this fabrication method. Heating devices are also made possible by the simple adaptation of the device for such purposes.
  • Next generation magnetic data storage technologies will likely utilize perpendicular magnetic media to store data.
  • Present technologies use lateral magnetic media in which the magnetic storage elements lie along the surface of the substrate.
  • the size of the basic elements must be reduced. This introduces a problem, however, since as the scale of these regions is reduced, so is the blocking temperature which marks the onset of superparamagnetism.
  • the blocking temperature must be kept large, otherwise the stored magnetization state of each element will decay and data will be lost.
  • One way to reduce the size scale of a magnetic media element without substantially reducing the blocking temperature is to utilize shape and volume, that is, to make small cylindrically-shaped objects of high aspect ratio (for example, from about 20:1, or about 35:1 or about 50:1 to about 10,000:1).
  • a cylindrically-shaped magnet of diameter 10 nm and length of 500 nm will have a much higher blocking temperature than that of a spherical magnet of 10 nm diameter.
  • the highest spatial packing density of magnetic cylinders occurs for cylinders in a vertical hexagonal closed-packed arrangement.
  • pure cobalt is a soft ferromagnet of relatively low coercivity and not necessarily an ideal material for magnetic data storage.
  • certain cobalt alloys have "designer" magnetic properties including engineered coercivity which makes them useful for present-day magnetic media applications. These cobalt alloys can be electro-deposited from a specific plating bath containing the relevant ions.
  • Magneto-electronic devices can be used for magnetic sensing applications (e.g., magnetic data storage) and for "spiiitronics" (e.g.,,MRAM).
  • Appropriately chosen nanoscale magnetic architectures can result in improved performance since magnetic interactions can be tuned at the nanometer scale.
  • the techniques described herein can be used to create devices in a variety of useful magneto-electronic configurations.
  • GMR giant magnetoresistive
  • the magnetic arrays made using techniques described herein show GMR type behavior.
  • the architecture of these arrays is significantly different than others that have been produced.
  • the important consideration for GMR device design is that there be electrical contact between the substrate and the magnetic nanowires, not whether the wires are embedded in the template or not. Therefore, the wires can be grown (that is, electrodeposited) to less than the film thickness for GMR devices without a need to remove matrix material prior to operability.
  • the ability to form a regular array of very small dimensions for example, an array of 25.4 nanometer period made of cylinders 11 nanometers in diameter.
  • the fabrication processes described herein permit the well-controlled height of the cylinders, and the ability to multilayer the cylinder material as it is grown. These new processing considerations have allowed the creation of new geometrical arcliitectures at size scales that have not been achieved using known fabrication processes. By tuning material structure in the fabrication processes described herein, a new breed of GMR materials is possible.
  • FIG. 10 A particular embodiment of a GMR device is shown in Fig. 10.
  • the device is created by fabricating a ma netic nanoarray as described herein on a substrate patterned with an electrode.
  • This particular magnetoresistive device is in a "lateral transport" configuration (the transport current is affected by the presence of the magnetic nanowires, but is not configured to pass through the wire along its length).
  • the matrix component of the copolymer is deleted from Fig. 10 for clarity.
  • the nanowires for such a device are desirably asymmetric magnetic hetero structures, as described above with respect to Fig. 13c.
  • Fig. 13c does not imply that in a given set of nanowires, all three types are used, rather that any one of the types can be employed in a set.
  • Smart media are media that sense this environment in a particular way, and create a measurable response. This could be, for example, a chemical sensor in which the device produces an electrical current when the presence of a particular type of molecule in solution is detected. Any electrical version of patterned smart media could be integrated with other signal processing on the same chip. Another example is a sensing medium that changes color upon sensing a change in chemical environment, temperature environment, optical stimulus, or other type of stimulus. Since the diblock systems are laterally patterned, arrays with large numbers of distinct sensing elements are fabricated. Each element is a localized transducer that is integrated into an on-chip circuit. Presently, the techniques described herein can be used to produce nanowire
  • Electrochemical Sensor Applications 1 9 arrays with a nanoelement density of approximately 1.2 x 10 elements/in . This ultimately enables data storage technologies with storage capacities exceeding a terabit/in 2 .
  • Patterned versions of high-density media in which one bit of data is encoded in the magnetization of a group of magnetic nanowires are created.
  • the patterned diblock-derived devices described herein provide a simple fabrication route to high storage densities.
  • nanoporous templates disclosed herein are used conveniently to make devices for electrochemical sensing as an array of "microelectrodes.”
  • microelectrode refers to a configuration of electrode that induces radial diffusion of an electrochemically-active species toward the electrode.
  • the behavior of a microelectrode differs dramatically from that of a planar electrode.
  • a nanoporous polymer template nanoelectrode array as described herein offers fast response, lower detection limits, and the possibility for molecular selectivity based on size or molecular interactions with the template.
  • the lateral-patterning invention advances the use of nanoporous templates for this purpose because several distinct microelectrodes arrays are configured onto the same chip using patterned diblock templates atop a pre-patterned thin-film electrode set.
  • Combinatorial chips are configured for DNA gene expression studies and other diagnostic applications.
  • the nanoporous polymer templates described herein are patterned and filled with metals or silicon oxide that are used to attach biomolecules that will enable new types of biomolecular research capabilities. Patterned versions of such structures are of far greater usefulness.
  • Another application for lateral patterning is to create structures for sorting molecules in nanoscales.
  • Photonic waveguides are able to have much smaller turn radius as compared to optical fiber. Such waveguides can be used to interconnect on-chip optical components.
  • Electrical interconnections to Nanowires can be made to nanowires made by patterned diblock copolymer templates. This is achieved by integrating the templating process with other pre- and post-processing steps.
  • Electrodes are prepattemed onto the substrate by a suitable lithographic technique.
  • a diblock copolymer film is deposited.
  • a metal layer is deposited.
  • a conventional (photo- or e-beam-) resist is deposited.
  • the cylinders of the diblock copolymer can be oriented by the techniques described herein.
  • the resulting structure is shown in Fig. 15 a. Selected areas of the top resist are exposed lithographically and removed by chemical development. Subsequently the exposed metal layer (#2) is removed by a metal etch.
  • the diblock film is exposed to ultraviolet (UV) light or an electronic beam, if it has not been exposed in a prior step.
  • UV ultraviolet
  • Fig. 15b The diblock film is now chemically developed with acetic acid or another suitable developer to result in a nanoporous template. If desired, the surface of the nanoporous template can be cleaned using a reactive ion etch with oxygen.
  • Fig. 15c This structure is shown in Fig. 15c.
  • Nanowires or other suitable nanostructures are now deposited into the pores of the nanoporous template. To achieve top electrical contact, the deposition can continue until electrical connection is made with the top layer. As discussed herein, a range of different desired nanostructures ⁇ can be deposited in the pores, depending on the target application. This structure is shown in Fig. 15d. hi some applications, such as field emissions arrays, electrical contact to the top layer is not desired. Rather, the isolated top metal layer would be used as an electrical gate in a triode field emission device configuration. In other applications, metal contact #2 can be replaced over the deposited nanowires to complete contact through the wires, as shown in Fig. 15e.
  • the integration scheme described in Figure 15 represents only one out of several schemes for integration and interfacing nanostructures made by patterned nanoporous templates. Nanofabrication via patterned diblock copolymers can be combined easily with other (pre- and post-) process steps, and done so such that the pattern is made in registry with previous lithographic patterns.
  • Electrodes are prepattemed onto the substrate by a suitable lithographic technique.
  • a diblock copolymer film is deposited.
  • the diblock cyclinders are then oriented , exposed lithographically in a desired pattern, and then developed into a nanoporous template.
  • Nanowires or other suitable nanostructures are now deposited mto the pores of the nanoporous template.
  • a suitable lithographic exposure and development a ion etch performed to remove degraded portions (for example, oxide) from the top of the nanowires, and then deposition of metal electrodes in the contact areas.
  • Example 1 A Prototype of a Field Emission Array
  • Figs. 8a-8d are 10X optical images of a prototype of a field emission array built by the inventors.
  • the silicon substrate was gold patterned with conventional lithography with a 1 micrometer thick, vertically oriented diblock copolymer film (polystyrene/polymethylmethacrylate, 70/30 by volume) covering the entire surface (the film is optically transparent).
  • Fig. 8b is an image of the same sample after electron-beam patterning in the shape of a square, and acetic acid development.
  • the inner square was a patterned nanoporous template.
  • the outer square was a solid film of crosslinked polystyreiie/polymethylmethacrylate made by intentional overexposure to radiation.
  • Fig. 8c is an image of the same sample after
  • Example 2 A Prototype Magnetoresistive Device
  • Figs. 11a and lib are 10X optical images of a prototypical four- wire magnetoresistive device made by the inventors.
  • An array of vertical magnetic nanowires stands atop a thin-film of gold pre-patterned into a four-probe resistor pattern. This device is used to investigate spin-dependent scattering in a "current-in- plane" (CIP) geometry where the scattering interface is geometrically periodic on the scale of tens of nanometers.
  • Fig. 1 la is an image of a substrate with a patterned electrode underlayer covered with an optically transparent diblock copolymer film layer prepared as described in Example 1.
  • the four probe resistor pattern was created as 2 ⁇ m in width and 100 ⁇ m in length, by standard electron beam lithography using a PMMA resist on a silicon substrate.
  • the thin-film resistor includes a 20 nm thick gold layer on top of a 1 nm Cr adhesion layer.
  • a 1.1 ⁇ m thick film of poly(styrene- ⁇ -methylmethacrylate) diblock copolymer denoted P(S- ⁇ -MMA) having 30% by volume polymethylmethacrylate (PMMA) with molecular weight of 42,000 Daltons was spun coated onto the patterned surface of substrate. This copolymer microphase separates into a hexagonal array of PMMA cylinders in a polystyrene (PS) matrix.
  • PS polystyrene
  • the sample was then exposed to an electron beam impinging on the sample in the shape of a square (area dose of 50 ⁇ C/cm 2 , with beam energy and current used is 20 kV and 2000 pA, respectively. Generally, for such diblock films of about 1 micron, the exposure dose can range from about 20 to about 200 ⁇ C/cm , with accelerating voltages and beam currents as described above. Optimal doses have been found to be about 80 ⁇ C/cm 2 .
  • the sample was then chemically developed with acetic acid. The original copolymer remains in the unexposed areas.
  • Cobalt nanowires were deposited in the pores on top of the gold pattern from an aqueous deposition bath, prepared by mixing 96 grams of CoSO -7H 2 O and 13.5 grams H 3 BO 3 in 300 ml pure H 2 O, with 60 ml of methanol added as surfactant, resulting in an electrolyte pH of 3.7.
  • the Co was electroplated at a reduction potential of -1.0V with respect to a saturated calomel reference electrode.
  • the nanowires were 500 nm in length.
  • Fig. lib is an image of the same sample after nanowire electrodeposition.
  • Structural information was obtained by performing small angle X-ray scattering (SAXS) and field emission scanning electron microscopy (FESEM).
  • SAXS data confirms a perpendicular nanowire orientation with a period of 21.7 nm.
  • the sample was cleaved in two, and FESEM used to examine a cross-section of the nanowire array.
  • the diameter of the nanowires was found to be approximately 11 nm, with a period of 21.8 nm.
  • the individual magnetic nanowires should be single-domain in equilibrium, and show interesting magnetoresistance (MR) effects, since the interwire spacing is less than the spin diffusion length.
  • MR magnetoresistance
  • the four- wire magnetoresistive device prepared in Example 2 was used for measurement.
  • the magnetic cobalt nanowire array is composed of 14 nm diameter wires, each 500 nm long, arranged in a hexagonal lattice with a period of 24 nm.
  • the structure of the device was verified by small-angle X-ray scattering measurements.
  • the magnetic field direction is parallel to the nanowire axis.
  • a cross sectional scamiing electron micrograph (SEM) image of such an array is shown in Fig. 12b.
  • the GMR ratio as a function of temperature between 2K and 300K is shown in Fig. 12a.
  • the data taken at 2K shows the largest amplitude curve, and that taken at 300K shows the smallest amplitude curve, with intermediate temperatures having intermediate values, with amplitudes in line with the ordering of the temperature.
  • FIG. 16a-c Other GMR ratios, as a function of orientation of magnetic field and temperature are shown in Figs. 16a-c.
  • the magnetoresistance is defined as [R(H) - R(50 kOe)/R(50 kOe)].
  • the data taken at 2K shows the largest amplitude curve, and that taken at 300K shows the smallest amplitude curve, with intermediate temperatures having intermediate values, with amplitudes in line with the ordering of the temperature.
  • the field is normal to the plane of the Au film (parallel to the Co nanowires) and the current direction.
  • Fig. 16b For the "transverse” orientation (Fig. 16b) and "longitudinal" orientation (Fig.
  • the field is in the plane of the gold film (perpendicular to the Co wires), but perpendicular or parallel to the current direction, respectively.
  • the different shapes and values for the MR curves for the three orientations provide evidence for the coexistence of anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR) scattering mechanisms in this system.
  • AMR anisotropic magnetoresistance
  • GMR giant magnetoresistance
  • MR behavior of the Co nanowires was also investigated as a function of gold film thickness and Co nanowire length.
  • Gold films of 7.5, 10 and 20 nm thickness were studied with Co nanowires of 500 nm.
  • samples of Co nanowire lengths of 100 and 500 nm were prepared having gold film thickness of 20 nm.
  • MR behavior was found to depend principally on nanowire length.
  • a plot of noraialized MR max for a perpendicular orientation at 0 field versus temperature for various gold film thicknesses and Co nanowire lengths is shown in Fig. 22. The characteristics clearly indicate that the temperature dependence of MR is strongly dependent on the Co nanowire length, but not so strongly on the gold film thickness.
  • Each data set is normalized to its 2K value for comparison.

Abstract

Pathways to rapid and reliable fabrication of three-dimensional nanostructures are provided. Simple methods are described for the production of well-ordered, multilevel nanostructures. This is accomplished by patterning block copolymer templates with selective exposure to a radiation source. The resulting multi-scale lithographic template can be treated with post-fabrication steps to produce multilevel, three-dimensional, integrated nanoscale media, devices, and systems.

Description

NANOFABRICATION
Government Rights
This invention was made with government support under U.S. Department of Energy Grant No. DE-FG02-96ERA45612, U.S. National Science Foundation Grant No. DMR-9809365, and U.S. National Science Foundation Grant No. CTS-9871782. The government has certain rights in this invention.
Technical Field
The invention relates to fabrication of nanoscopic structures, hi particular, the invention relates to functionalized nanoscopic structures on surfaces.
Background
The fabrication of useful nanoscale devices has proved difficult. Approaches based on porous aluminum oxide (Anopore™), ion-track-etched polycarbonate (Nuclepore™), ion-track-etched mica, and other approaches, have been attempted. Examples of these are disclosed by Mitchell et al., in "Template-Synthesized
Nanomaterials in Electrochemistry", Electroanalytical Chemistry, A. J. Bard and I. Rubinstein, Eds., 21, (1999), 1-74; Strijkers et al, in "Structure and Magnetization of Arrays of Electrodeposited Co Wires in Anodic Alumina," J App. Phys., 86, (1999), 5141; Han et al., in "Preparation of Noble Metal Nanowires Using Hexagonal Mesoporous Silica SBA- 15," Chem. Mater. , 12, (2000), 2068-2069; Whitney et al., in "Fabrication and Magnetic Properties of Arrays of Metallic Nanowires," Science, 261, (1993), 1316; and in United States Patent No. 6,185,961 for "Nanopost arrays and process for making same," to Tonucci et al.; and United States Patent No. 6,187,165 for "Arrays of semi-metallic bismuth nanowires and fabrication techniques therefor," to Chien et al. These approaches result in materials which can be very difficult or impossible to pattern laterally and/or integrate. Other devices which can be prepared are macroscopic in scale, as disclosed in United States Patent No. 6,187,164 for a "Method for creating and testing a combinatorial array employing individually addressable electrodes ," to Warren et al. Recently, companies such as Samsung and Hitachi have used carbon nanotubes as field emission sources to make prototype field emission (FE) displays. FE devices based on carbon nanotube materials are disclosed in "Flat panel display prototype using gated carbon nanotube field emitters," by Wang et al., App. Phys. Lett., 78, (2001) 1294, and can provide acceptable field emission, but can be difficult to fabricate.
Serial writing processes can be used to pattern magnetic media, as disclosed in "Writing and reading perpendicular magnetic recording media patterned by a focused ion beam," by Lohau et al., App. Phys. Lett, 78, (2001), 990, and "Magnetic block array for patterned magnetic media" by Koike, et al, App. Phys. Lett, 78, (2001), 784. Researchers at IBM Almaden Research Center have utilized a fabrication scheme that resulted in patterned media having storage density of 100 Gb/in2, as described in Lohau et al. This scheme used a focused Ga+ ion beam to cut trenches in granular Co70Cr 8Ptι2 film media. These processes tend to be slow, and are not well suited to high throughput manufacture.
The efficiency of thermoelectric (TE) cooling devices has not increased significantly during the last 40 years, and currently, the figure-of-merit (ZT) of the best materials is less than one. Semimetal materials such as Bi and Bi2Te3 have the highest ZT values and are currently used in commercial TE devices manufactured by companies such as Marlow and Melcor.
Summary
By laterally patterning nanoscale arrays, a pathway to a rapid and reliable fabrication of three-dimensional nanostructures is provided. A simple method is described herein for the production of well-ordered, multilevel nanostructures. This is accomplished by patterning block copolymer templates with selective exposure to a radiation source. The resulting multi-scale lithographic template can be treated with post-fabrication steps to produce multilevel, three-dimensional, integrated nanoscale media, devices, and systems. h one aspect, the invention provides a method of preparing a laterally patterned array. The method includes coating some of conducting or semiconducting substrate (for example, a metal, such as gold) with a block copolymer film (for example, a block copolymer of methylmethacrylate and styrene), where one component of the copolymer forms nanoscopic cylinders in a matrix of another component of the copolymer; placing a conducting layer on top of the copolymer to form a composite structure; vertically orienting the composite structure; removing some of the first component fi-om some of the structure to form nanoscopic pores in that region of the second component; cross-linking the second component; and at least partially filling some of the nanoscopic pores with a material.
The substrate can include conducting and non-conducting regions, which can be lithographically patterned. In such cases, a first component can be removed from some of the structure which is at least partially overlaying a conductmg portion of the substrate. The structure can be vertically oriented by heating with an electric field, for example, for at least one hour. Some of the first component can be removed by exposing some of the structure to ultraviolet radiation, an electron beam, or ozone. Some of the first component can be removed by degrading the component and treating some of the structure with an agent that selectively removes the degraded component. Some of the nanoscopic pores can be filled by electrochemical deposition. Some of the nanoscopic pores and surface of the second component can be wetted with a surfactant prior to filling with material. Electrical current can be controlled to determine the amount of material deposited in the pores. In another aspect, the invention provides an array manufactured by the methods described herein. The array can include a substrate, a polymer film on the substrate, and at least one set of parallel metallic (for example, gold, copper or nickel) or semi-metallic cylinders in the film, and arranged perpendicular to the substrate. The cylinders can include a magnetic material, such as cobalt or nickel. The magnetic arrays can be used to make a magnetic storage medium, or a magnetoresistance device, or a giant magnetoresistive device. Non-magnetic metals can be used in such arrays to make, for example, a field emission device, hi some embodiments of these arrays, at least one set of cylinders includes n-type material and at least another set of cylinders includes p-type material. Such an array can be used to create a thermoelectric cooler. The cylinders can also include alternating layers of magnetic and non-magnetic material, whether the layers alternate substantially regularly along the length of the cylinders or not. h such arrays, the sets of cylinders can be configured in substantially regular geometrical shapes, such as circles or triangles. Of course, irregular shapes can also find application in the devices disclosed herein. In some of the arrays, one type of cylinder has a given magnetization direction, and another type has an opposite magentization direction, h some embodiments, at least one set of cylinders is in electrical contact with another set of cylinders, for example, by a conductive contact on top of the film.
As used herein, the term "vertically-oriented," when referring to a copolymer film means a film that has cylindrical pores with the axis of the pores substantially noraial to the surface with which the film is associated, or substantially noraial to the film surface itself. The new materials can have cylindrical pores that are vertically oriented, or oriented at an angle to vertical, as long as the cylinders are oriented in substantially the same direction, e.g., in parallel. These cylinders can have various shapes and can, but need not, have a circular diameter cross-section. As used herein, the term "nanoscale" refers to a characteristic size range, for example, of arrays, that is attained using the methods of self-assembly of copolymer molecules described herein. For example, the pore diameter, the wire diameter, the wire lengths and the period of the array can be in the nanoscale range, that is, within a range of about a nanometer to over a thousand nanometers. As used herein the term "nanowire" refers to nanoscale material created in an array pore. The term does not imply that the aspect ratio of the material need be high, and in some embodiments, the material to be deposited in an array can have a low aspect ratio. "Nanowires" can also refer to material that is not necessarily electrically conductive, but is nevertheless, useful when present in nanoscale arrays. As used herein, the term "multilevel" refers to structures that can be constructed by multiple, independent levels of lithography, with at least one level created with a laterally-patterned diblock copolymer film. As used herein, the term "multilayering" refers to a structural element within a single layer of lithography that contains more than one material. As used herein, the term "wire" refers to conductive material having width and length, where the aspect ratio (that is the ratio of length to width) is at least 2:1. This term is distinguishable from the term "dot," which refers to conductive material with lower aspect ratios.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control, h addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
The techniques and systems described herein include many advantages. For - example, the extremely high density of the magnetic cylinders in the new films offers the capability of using this system for next-generation magnetic data storage applications, with potential data storage densities in excess of 1000 Gbit/in2. The well-controlled size and separation distance of the magnetic metals on the metal, e.g., gold, film also offer the means to engineer next-generation giant-magnetoresistance magnetic-field-sensing devices.
The processes are parallel, scaleable, and not subject to the speed limitations experienced in nanofabrication techniques based on serial writing. The teclmiques are amenable to manufacture, in that they are simple, fast, and cost-effective. They are readily adoptable by industry and compatible with other fabrication processes.
The techniques described herein significantly advance the general utility of nanofabrication by self- assembling copolymer templates. The nanofabrication techniques are amenable to manufacture, in that they are simple, fast, and cost- effective. They are readily adoptable by industry and compatible with other industrial microfabrication processes. For example, lateral patterning offers the capability of using such systems for the manufacture of electronic circuits on chips. The integration of nanostructures within chips and the interfacing of the structures with other chip elements in arbitrary locations is made possible through the methods disclosed herein. For example, these three-dimensional structures offer the means to engineer electronic field-emission arrays. The arrays can be used in flat panel displays that are brighter, higher-resolution, less expensive, thim er, and more flexible than those currently available. Other field emission electron devices are possible, such as transistor-like devices, spin-polarized electron emitters, and other lαiown devices based on field emission.
For example, the three-dimensional structures also offer the means to engineer solid-state thermoelectric cooling devices, including those with multistage cooling. Other applications include magnetoresistive sensors, high-capacity magnetic data storage, smart media, spiiitronics, chemical-sensing devices, biomoleciilar diagnostic sensor arrays, designer "micromagnetic" media, and molecular electronics, for example.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims. Brief Description of the Drawings
Fig. 1 is a schematic diagram of an exposure process that can be used to create a nanoporous array, and subsequently can be used to create an array of nanowires.
Fig. 2a is a side view schematic diagram of a selective exposure process that can be used to create a laterally patterned diblock copolymer film. Fig. 2b is an overhead view schematic diagram of a selective exposure process that can be used to create a laterally patterned diblock copolymer film, in this case, a triangle pattern.
Fig. 3 is a schematic diagram of a selective exposure process that can be used to create a laterally patterned diblock copolymer film, and subsequently can be used to create a laterally patterned nano structure, in this case, a triangle shaped nanostructure.
Fig. 4 is a perspective view schematic diagram of a multilevel nanostructure created from laterally patterned diblock copolymer film.
Fig. 5 is an overhead view schematic diagram of a multilevel nanostructure created from laterally patterned diblock copolymer film. Fig. 6 is a perspective view schematic diagram of a field emission array created from laterally patterned diblock copolymer film, including two sets of nanowires.
Fig. 7 is an overhead view schematic diagram of a field emission array created from laterally patterned diblock copolymer film, including four individually- addressable sets of nanowires.
Fig. 8a is an overhead view optical image (at 5X) of a sample showing an electrode pattern with a vertically-oriented diblock copolymer film covering the surface. Fig. 8b is an overhead view optical image (at 5X) of the sample from Fig. 8a after electron beam patterning and removal of a copolymer component to form nanopores.
Fig. 8c is an overhead view optical image (at 5X) of the sample from Fig. 8b after nanowires are electrodeposited on the sample. Fig. 8d is a closeup overhead view optical image (at 5X) of the sample from
Fig. 8c.
Fig. 9 is a perspective view schematic diagram of a single-stage thermoelectric cooler created from laterally patterned diblock copolymer film.
Fig. 10 is a perspective view schematic diagram of a four- wire, giant magnetoresistive (GMR) device created from laterally patterned diblock copolymer film.
Fig. 11a is an overhead view optical image (at 10X) of a four-wire magnetoresistive device created from laterally patterned diblock copolymer film before nanowire electrodeposition. Fig. 1 lb is an overhead view optical image (at 10X) of a four- wire magnetoresistive device created from laterally patterned diblock copolymer film after nanowire electrodeposition.
Fig. 12a is a graph of giant magnetoresistance measurements of a four- wire device as depicted in Fig. ' 1 lb, as a function of device temperature. Fig. 12b is a scanning electron micrograph SEM image of vertically oriented nanowires created from laterally patterned diblock copolymer film.
Fig. 13 a is a side view schematic diagram of a particular configuration of a magneto-electronic transport nanodevice created from laterally patterned diblock copolymer film, where the "current in" and "current out" electrodes are both on the substrate level.
Fig. 13b is a perspective view schematic diagram of a further particular configuration of a magneto-electronic transport nanodevice created from laterally patterned diblock copolymer film, where the "current in" electrode is on the substrate level, and the "current out" electrode is on an upper interconnect level.
Fig. 13c is a side view schematic diagram of three distinct types of magneto- electronic nanoelements used in the devices of Figs. 13a and 13b.
Fig. 14a is an overhead view schematic diagram of a particular example of patterned media, showing patterned perpendicular media. Fig. 14b is an overhead view schematic diagram of a further particular example of patterned media, showing customized patterned perpendicular media.
Fig. 15a-e is a schematic depiction of a method of interfacing metal electrodes with the button and top of nanostructures made by a nanoscale diblock copolymer template. Figs. 16a-c is a series of graphs of magnetoresistance measurements for the device depicted in Fig. 1 lb, taken a various magnetic field orientations.
Fig. 17 is a microscope photograph of a device constructed as shown in Fig. 13.
Fig. 18 is a graph of magnetoresistance measurement of electron transport through the device shown in Fig. 17.
Fig. 19 is a microscope photograph of a field emission test sample from a device constructed as depicted in Fig. 6.
Fig. 20 is a graph of electronic field emission measurements made from an array of cobalt wires in vacuum, from the device shown in Fig. 19. Fig. 21 is a microscope photograph of particular field emission test samples from Fig. 19, but magnified to 50x.
Fig. 22 is a plot of normalized MR response (%) at 0 field versus temperature, in the perpendicular orientation. Detailed Description
Described herein is a process technology for the fabrication of three- dimensional devices using laterally-patterned block copolymer templates. In this method, copolymer films are patterned laterally by selective-area exposure to radiation sources. This produces a multi-scale lithographic template, that is, a regular array of nanoscale pores with an overall lateral extent confined to an arbitrary and desired design. The dimensions of the lateral design can range from the nanoscale to the microscale. The patterned array template is combined with appropriately tailored pre- and post- fabrication steps to produce multilevel, three-dimensional integrated nanoscale media, devices, and systems. The method introduces the ability to integrate nanoscale functional elements in arbitrary and desired locations on a chip and to integrate the functional elements with other chip components in a practical manner. The general utility of self-assembled copolymer templates is thereby significantly advanced.
General Preparative Technique
The methods described here are based on the formation of regular arrays of material on surfaces. For example, diblock copolymers, comprised of two chemically distinct polymers covalently linked end-to-end, can be self-assembled into well- ordered arrays of spheres, cylinders or lamellae, depending on the volume fraction of the components comprising the polymer chain. Directed self assembly, carried out with an external field (for example an electric or magnetic field, or a temperature or concentration gradient), can result in useful films, with orientation sufficiently long- ranged to allow the production of extended arrays of nanowires having aspect ratios of at least 2:1 or 3 : 1. Vertically-oriented, cylindrical phase diblock copolymer films are created. Among many suitable diblock copolymers that can be use, a 70/30 (by volume fraction) polystyrene-polymethylmethacrylate diblock copolymer can be exemplified. Other cylinder constituents of the copolymer can be, for example, polybutadienes, polycaprolactones, and other materials that can be solubilized in solvents. Other matrix constituents can include polybutadienes and other materials which are not reactive with agents used to remove the cylinder constituents.
A block copolymer is first deposited, e.g., spun-cast from solution onto a substrate, such as a metallic, semiconducting, or insulating substrate. The substrate can be rigid or flexible. Of particular interest are: substrates at least partially coated with a thin film of metal; semiconducting substrates; and semiconducting substrates at least partially coated with a lithographically-designed thin film metal electrode pattern. Suitable substrates include: silicon, such as silicon wafers or chips; and polymeric substrates, such as Kapon, each of which can be made conducting or semiconducting by coating at least a portion of the substrate surface with a conductmg or semiconducting material. Among metal substrates, for particular applications, the oxidation of the metal should not be as rapid as the deposition rate of materials to be deposited.
For example, substrates for use in the devices and techniques described herein may be a coating or a non-continuous surface layer on an underlying material that need not be conducting. The amount of substrate used can be any amount that allows the substrate to function as an electrode, when electrodeposition is used to deposit functional material. If other methods of material deposition are employed, the nature and amount of substrate is not limited. The substrate, in embodiments in which it is present as a coating or surface layer, can be applied to an underlying substrate by conventional lithographic techniques, or other lαiown methods of depositing conducting materials on surfaces. hi some embodiments, the substrate can include metals, for example, gold. In other embodiments, the substrate can have gold coated or deposited on an underlying material. In some embodiments, the substrate can be a semi-metal oxide, including for example, silicon oxide. Particular preparation methods are not required, although in some embodiments, washing the substrate with water, followed by rinsing with mild acid and/or base can be carried out. Diblock copolymers, comprised of two chemically distinct polymers covalently linked end-to-end, can be self-assembled into well-ordered arrays of spheres, cylinders or lamellae, depending on the volume fraction of the components comprising the polymer chain. If the volume fraction of a major component is about 0.7 (e.g., from about 0.65 to about 0.80), any copolymer will self-assemble into a hexagonal array of cylinders of the minor component embedded in a matrix of the major component. The mole ratio of the minor component of the diblock copolymer can range from about 0.20 to about 0.35 to permit the formation of microphases such as will result in cylinder formation. If the volume fraction of the major component is about 0.9, the minor component will form spheres, which can be elongated into very thin cylinders when an orienting field, e.g., an electric field, is applied.
A mixture of diblock copolymers, such as A-B and A-C diblock copolymers, can be used to create cylinders of different types, for example B and C cylinders. Higher block copolymers, such as A-B-C triblock copolymers can also be used. The molecular weight of the copolymer can be varied to achieve differing cylinder diameters. For example, a molecular weight copolymer in the range of about 1.5 million molecular weight units (Daltons) can result in a cylinder diameter of about 70 nm. A molecular weight in the range of about 20,000 Daltons can result in a cylinder diameter of about 14 nm. A molecular weight of about 4 million Daltons results in cylinders with a diameter of about 100 nm, while a molecular weight of about 15 kilodaltons results in a diameter of about 1.0 nm.
For some embodiments, the use of a block copolymer including a component that can be crosslinked is desirable. This component can be crosslinked before or during removal of another component, and can therefore add structural integrity to the copolymer. This component can be referred to as the matrix component, hi some embodiments, the matrix component will be the major component of a copolymer, by volume. Suitable matrix components include polystyrene, polybutadiene, polydimethylsiloxane, and other polymers. The component that is to be removed can be called the core component, hi some embodiments, the core component will be a minor component of a copolymer, by volume. Suitable core components include polymethylmethacrylate, polybutadiene, polycaprolactone or a photoresist. Generally, core components are materials that can be degraded or decomposed differentially than the matrix material. hi other embodiments, block copolymers of styrene and methylmethacrylate can be used. In some embodiments, the methylmethacrylate block constitutes a minor component. For example, a 70/30 (by volume) diblock copolymer of polystyrene/polymethylmethacrylate can be employed. Any block copolymers can be used, such as alkyl/alkyl, alkyl/aryl, aryl/aryl, hydrophilic/hydrophilic, hydrophilic/hydrophobic, hydrophobic/hydrophobic, positively or negatively charged/positively or negatively charged, uncharged/positively or negatively charged, or uncharged/uncharged. The film thickness can vary as desired, for example, from about 0.5 nm to about 10 cm, or from about 1 nm to about 1 cm, or fi-om about 5 nm to about 1000 nm. hi some preferred embodiments, film thicknesses can vary from between about 10 nm to about 200 microns, or from about 1 micron to 200 microns, or up to about 25 mil. Orientation of the copolymers can be carried out using directed self-assembly, that is, self-assembly which is directed by an external field, for example an electric field, a magnetic field, a thermal gradient or a concentration gradient. Vertical orientation of the cylinders can be accomplished by, for example, electric field alignment under annealing conditions, or, for example, self-orientation using controlled interfacial conditions.
For electric field-induced orientation, the different chemical constitutions of the blocks of the copolymer can result in a difference in the dielectric constants of the copolymer domains. A difference of about 0.1% in the dielectric constants can result in a specific, e.g., vertical, orientation, h an electric field, the orientation dependent polarization energy associated with the cylinders, dielectric bodies that are anisotropic in shape, will align the cylinders in parallel to the electric field lines, for example, as described in Morkved, et al., "Local control of microdomain orientation in diblock copolymer thin films with electric fields," Science, 273, (1996), 931; Thurn-Albrecht, et al., "Overcoming Interfacial Interactions with Electric Fields," Macromolecules, 33, (2000) 3250-53; Amundson, et al., "Alignment of lamellar block-copolymer microstructure in an electric-field. 1. Alignment kinetics," Macromolecules 26, (1993), 2698; and Amundson, et al., "Alignment of lamellar block-copolymer microstructure in an electric-field. 2. Mechanisms of alignment," Macromolecules 27, (1994), 6559.
Under strong enough fields parallel to the substrate, any surface induced alignment of the morphology can be overcome, producing cylindrical microdomains oriented in parallel with the fields, which can be normal to the substrate, that extend completely through a one-micron-thick sample. Scattering experiments are an easy means to characterize the orientation of the microphase structure in a thin film. When viewed from the side, a cylindrical structure oriented noraial to the substrate is laterally periodic. Consequently, the scattering pattern measured at a finite incidence angle is strongly anisotropic, consisting of two equatorial Bragg peaks. hi some embodiments employing an electrical field to orient the polymer film, a removable conducting layer is placed on top of the copolymer film, sandwiching the film between two electrodes. For example, a conducting layer can be deposited by spin coating and then, after annealing, be removed by etching, e.g., by solvent chemical, or physical etching. Alternatively, a "spin-on" sacrificial layer can be applied, followed by a metal layer that is evaporated, sputtered, or spun-on. After annealing, the sacrificial layer can be removed by solvent, chemical, or physical etching. This conducting layer can be metal, or semiconducting material, and can optionally be in contact with the entire film surface. For example, aluminum, copper, gold or other metal can be used as the conducting layer on the copolymer film.
Metallized layers, such as aluminized KAPTON® can also be used. Metallized layers can promote the formation of a uniform film surface as orientation, e.g., vertical orientation, is carried out. For example, in some embodiments, the use of a metal conducting layer alone, in direct contact with the copolymer film, can result in damage to the copolymer layer as the conducting layer is removed, due to sticking and/or tearing. Aluminized Kapton® is a layer of aluminum in register with a layer of Kapton®, in which the Kapton® layer is directly in contact with the copolymer film. The Kapton® layer must not be so thick as to interfere with an electric field established between the aluminum layer and the substrate on the other side of the film. Other metals and other polymeric materials can be used to create metallized layers for electric field-induced vertical orientation.
To mobilize the molecules in the copolymer, the sandwich structure can be heated above the glass transition temperature of the copolymer. Voltage is then applied between the substrate and the conducting layer to create an electric field through the mobilized copolymer film. The electric field strengths are at least 5 V/mm, for example, at least 10 V/mm.
After holding the film in this state for a sufficient time to allow the copolymers to self-assemble, for example, over 30 minutes, over 60 minutes, over 1.5, over 2, or over 3 hours, the copolymer film assembly is cooled to a temperature below the glass transition temperature of the copolymer. The orienting field, e.g., electric field, is desirably turned off after the cooling has taken place. At this point the conducting layer, and any associated additional layer, is removed from the polymer film. The film now includes an ordered array of cylinders of one copolymer component embedded in a matrix of another copolymer component. Self-assembly results in parallel orientation of the blocks, such that one component forms cylinders with the cylinder axis substantially in parallel to each other, e.g., all normal to the surface of the substrate, or substantially normal to the film surface itself. The cylinders desirably extend substantially from the substrate surface to the surface of the film. The cylinders have diameters ranging from about 5 nm to about 100 nm. The periodicity (L) of the cylindrical domains in the film is the distance between the central axes of the cylinders, and is proportional to the molecular weight of the copolymer (to the 2/3 power). In embodiments in which the mole fraction of the minor component is from 0.2 to 0.35, and the cylinders are hexagonally packed, the periodicity defines the diameter of the cylinders. Periodicity can range, for example, from about 1.0 to about 70 nm, but can be outside this range. hi other embodiments, methods other than heating are used to make the molecules of the copolymer mobile. For example, rather than heating the copolymer to its glass transition temperature, one can, in effect, lower the glass transition temperature, by any of a number of ways. For example, one can add a plasticizer, a solvent, or a supercritical fluid, such as supercritical CO2, to the copolymer to mobilize the molecules and allow them to move and self-assemble. An orienting field is applied, and the plasticizer, solvent, or supercritical fluid is removed to immobilize the molecules. Thereafter, the orienting field is removed, but the immobilized molecules maintain their orientation. Orientation using electric field allows a wide range of film thicknesses to be prepared, and thereby a wide range of nanowire aspect ratios to be produced. Nanowire aspect ratios can range, for example, from about 0.05:1 to about 10,000:1; or about 0.1 :1 to about 5,000:1; or about 1:1 to about 500:1; or about 2:1 to about 10,000:1 or about 2:1 to about 5,000:1, or about 2:1 to about 500:1,- or about 2:1 to about 100:1. Such large aspect ratio wires in an extended array are useful for creating sufficiently large magnetic coercivity though shape anisotropy, for example.
Orientation using controlled interfacial interaction is well suited for relatively thin diblock films. For example, less than about lOOnm, or less than about 60nm, or less than about 40nm thick. According to such methods, a substrate is pre-treated so that it presents a "neutral" surface to a copolymer diblock film. Hydrogen-passivated silicon, or silicon coated with a random-copolymer brash, are suitable exemplary neutral surfaces. Thin diblock films can be spun-cast atop this surface and annealed. The cylinders will self-orient vertically without directed self assembly from an external field in sufficiently thin diblock films, for example, films of less than about lOOnm.
Such methods result in a very flat film surface and simplify manufacture, since the application and subsequent removal of a top electrode are not strictly required. Ultra-high density magnetic data storage can be achieved if magnetic materials having larger intrinsic anisotropies than cobalt are used. (FePt for example.) High pattern resolution on thin films is possible using an electron beam for lateral patterning.
The surface of the copolymer film obtained after orientation can be used as formed for a number of applications. For some applications, the surface of the vertically oriented copolymer film is desirably substantially smooth. Such arrays and techniques for producing substantially flat surfaces are described in United States Provisional Patent Application Serial No. 60/191,340, filed March 22, 2000, titled
"Magnetic Arrays;" and United States Patent Application Serial No. 09/814,891, filed March 22, 2001, titled "Nanocylinder Arrays," and each application is incorporated herein by reference in its entirety. For example, for magnetic data storage applications, in which a reading device passes rapidly over a magnetic array, the surface is desirably smooth. Any application in which a read or write head passes over an array can require high smoothness. Smoothness of a magnetic array for data storage and retrieval applications desirably ranges from about 0.5 to about 5.0 nm. The surfaces of vertically oriented copolymer films can be made smooth with the use of an additional material, such as an elastomer or a crosslinked elastomer applied to the conducting layer before vertical orientation steps are undertaken. For example, an additional material, such as a crosslinked silicone, including crosslin ed- polydialkylsiloxanes, -polydiarylsiloxanes, or -polyalkyl-arylsiloxanes, including, for example, crosslinked-polydimethylsiloxane, can be applied to a conducting layer, or in some embodiments, to an additional layer, as described above. The conducting layer, and/or any associated additional layer, is coated with the additional elastomeric material, and the layers placed in contact with the copolymer film. Vertical orientation is carried out, as described above, and the layers removed from the surface of the vertically oriented copolymer film. The surface can be made thereby smoother than surfaces created without the additional elastomeric material.
Next, the minor component (or in some embodiments the major component) of the substrate-associated copolymer is removed (either component of a diblock copolymer can be "minor" or "major," and the components can also be equally present). Removal of the minor component is achieved, e.g., by exposure to radiation (ultraviolet light, x-ray radiation, gamma radiation, visible light, heat, or an electron beam or any other radiation source which selectively degrades the minor component). Degradation or decomposing agents such as reactive oxygen species, including for example, ozone, or solvents such as ethanol, can also be used. Ultraviolet light can be used to degrade, for example, polymethylmethacrylate as a core component. Ethanol can be used to degrade, for example, polybutadiene.
This treatment can be followed by a chemical rinse to remove the decomposition by-product, and typically results in porous material having pore sizes in the tens of nanometer range. A step to remove any residual component can include treatment with a liquid, including washing with a solvent, or a material that reacts preferentially with the residual component, such as an acid or a base, hi some embodiments, the material used to react with residual degraded component can be, for example, a dilute form of acetic acid. The volume formerly filled by a now removed copolymer component now comprises cylindrical spaces extending through the thickness of the film. The remaining volume is occupied by the remainder copolymer component and is referred to as the matrix.
In some embodiments, it may be desirable to optionally cross-link a component of the copolymer film. Cross-linking of a component that is not degraded by an energy source or agent can add structural strength to the film, h some embodiments, a copolymer component is crosslinked simultaneously with the degradation of another copolymer component. The radiation can optionally and desirably crosslink and substantially immobilize the matrix component of the diblock copolymer, so that the matrix maintains the array structure even after the cylindrical voids are created. A nanoporous array template is the resulting overall structure. For example, in the case of polymethylmethacrylate (PMMA) cylinders in a polystyrene (PS) matrix, ultraviolet radiation degrades the PMMA while crosslinking the PS. It is desirable that the initial morphology of the copolymer be retained throughout the entire process of degradation. Other methods of removing one or the other component (e.g., chemical methods) can be used. Either the "minor" or "major" component can be removed or be remaining. The dimensions of the pores generally are the same as those of the cylindrical domains of the vertically oriented copolymer film, and as such, the pore diameters can range from about 5 nm to about 100 nm or more, and the periodicity can range from about 5.0 to 70 nm. Subsequently, the resulting pores are at least partially filled with, for example, metallic, metalloid, semiconductor, and/or magnetic materials. Deposition of functional material can be carried out by, for example, electrodeposition, chemical vapor deposition, electroless deposition, surface chemistry, chemical adsorption, and chemically driven layer-by-layer deposition. For deposition of material in pores that have depths of more than about 30 nm, electrodeposition is a desirable method, since it provides a driving force for the deposition of material into the bottoms of the pores. For example electrodeposition within the pores of a nanoscale template derived from films of diblock copolymers provides a convenient means of filling the large aspect-ratio pores in a highly controlled manner to provide an array of nanowires.
For those applications relying on magnetic properties of the array, the nanowires include at least some magnetic material. Magnetic materials include cobalt, nickel, iron, and alloys which contain one or more of these materials, and includes those materials which are measurably magnetic. For those applications relying on magnetic properties of the array, the nanowires include at least some magnetic material. Magnetic materials are those materials that are measurably magnetic, and can include magnetic metals, such as cobalt, nickel, iron, rare-earth magnetic materials, and alloys that contain one or more of these materials (such as iron-platinum alloys, or PERMALLOY®, an alloy of iron and nickel, with a stoichiometry of Ni8ιFeι9), as well as magnetic non-metals, including ceramic materials such as strontium or barium in combination with iron oxide. Organic magnets, such as tetracyanoethyleiie, can also be employed as magnetic materials. Magnetic systems can also contain materials that are non-magnetic, including nonmagnetic metals, such as copper, gold, silver, and the like.
Magnetic materials can also be prepared as magnetic nanowires by deposition of alternating layers of magnetic metals and non-magnetic materials. Such alternating layers can be optionally and, for some embodiments desirably, regularly alternating, and the regularity can include regularly alternating amounts of such materials. For example, a magnetic nanowire can include at least three layers of material alternating as: magnetic metal, non-magnetic material, magnetic metal; or non-magnetic material, magnetic metal, non-magnetic material. The alternating layers can be optionally, and in some embodiments desirably, non-regularly alternating. More details are given in "Magnetic Multilayers and Giant Magnetoresistance : Fundamentals and Industrial Applications (Springer Series in Surface Sciences, No 37)," Uwe Hartmann (editor), 370 pages, (Springer- Verlag, 2000), which is incorporated herein by reference. Cobalt/copper alternating multilayers have been found to be useful. Magnetic materials can be generally chosen to have a selected magnetic coercivity, which will depend on the desired application. For example, by using just cobalt (Co) nanowires, the coercivity can range from about 7000 Oe, to any lower number. Under appropriate fabrication conditions, the perpendicular coercivity of a cobalt nanowire array can exceed 1.7 kOe at 300K, due to the cylindrical shape anisotropy and nanowires having diameters smaller than the size of a single magnetic domain. The coercivity can be tuned to smaller values by selecting specific electrodeposition conditions, pore diameter, and additives. For example, using the techniques described herein (applied field perpendicular to the substrate and parallel to wire axis), one can establish perpendicular coercivity of about 800 Oe at room temperature. Higher coercivities can be obtained by depositing rare earth magnetic materials.
Magnetic materials can also have their magnetoresistive behavior tuned by adjusting the thickness of the magnetic sections, the thickness of the noraial metal sections, and the diameter of the multilayered nanowires. These devices are so-called "giant" magnetoresistive devices, which are sensitive magnetic field sensors, in that the resistance changes dramatically with a change in magnetic field. One can also intentionally make "two-state" devices using non-regular multilayering. For example, a thick magnetic layer, followed by a thin normal metal layer, and then followed by a thin magnetic layer can be deposited in nanowires to form an array useful to design a two-state device. hi other embodiments, one can reverse the magnetization state of the smaller magnetic layer by increasing the current through the device. A spin-polarized electron current leaves the larger magnetic region and is injected into the smaller magnet. This current exerts a torque on the magnetization in the smaller magnet and can reverse the direction of magnetization. The change in magnetization is typically accompanied by a discrete change in measured resistance. This results in a way to "write and read" using current. One can "write" with a larger current, and "read" with a smaller current. These concepts are discussed in Katine et al., "Current-driven magnetization reversal and spin- ave excitations in Co/Cu/Co pillars," Phys. Rev. Lett., 84, (2000), 3149. Optimal electrodeposition of magnetic material can involve the alignment of the magnetic axis of the material normal to the surface upon which the magnetic material is deposited.
For those applications which do not rely on magnetic properties of arrays, any other material which can be electrodeposited can be employed, including metals generally, semi-metals (including, for example, Bi and BiTe), and certain semiconducting materials that can be electrodeposited. Optimal electrodeposition of magnetic material can involve the alignment of the magnetic axis of the material substantially, parallel or skew noraial to the surface upon which the magnetic material is deposited. The technique described above is generally depicted in Fig. 1, which shows an oriented diblock copolymer film on a substrate. The dark areas on the substrate represent one of the components of the diblock copolymer, and the adjacent lighter areas represent the other component of the diblock copolymer. The upper surface of the copolymer film is here shown perfectly flat. This condition can be preferable for some applications, although this is not a requirement for the technique generally. Those applications which desirably involve the production of substantially flat film surfaces can utilize methods which use a further polymer on top of the copolymer film. For example, polydimethylsiloxane can be deposited across the surface of the copolymer film to produce a substantially flat surface on the copolymer film. For particular applications, the matrix material is desirably removed from the substrate surface after deposition of functional material. In other applications, the matrix material is desirably present subsequent to deposition to provide structural stability to the array of nanowires, or to allow further post-fabrication lithographic steps. Removal of matrix material can be achieved by treating the array with an agent that selectively degrades the matrix material with respect to the nanowires as described above.
Selective Exposure
The methods of certain embodiments described herein are based on the selective exposure of the diblock copolymer template to a radiation source which removes material fi-om the polymer film, to create three-dimensional nanoscale elements in a multilevel integrative technology. Special multilevel processing steps, specifically tailored to each particular device configuration, are used to achieve the complex integration. A simple product may require patterned diblock level of lithography only, while a complex integrated product may also require pre- and post- fabrication lithographic steps. The common technique to all cases of nanostructure fabrication is the selective copolymer patterning technique.
The process involves the selective alteration of specific areas or location of a nanoporous copolymer template, e.g., by exposure to a radiation source. Suitable radiation sources for the selective degradation of a copolymer component include, for example, ultraviolet (UV) light, electron beams, or other sources of radiation that can efficiently degrade a component of a diblock copolymer. The process is depicted generally in Fig. 2a, which shows a side view of a vertically oriented diblock copolymer film on a surface, with radiation impinging on the copolymer film. The radiation removes material from the film to create cylinders, and since the exposure is selective, there are areas of the film that contain cylinders, and areas which do not. Fig. 2b is an overhead view of the same film, showing explicitly that, in this case, a triangular shape has been imposed on the film surface, resulting in an area where electrodeposition can potentially be carried out, depending on the characteristics of the underlying surface. Fig. 3 depicts the same process and resulting template, with the matrix component of the film deleted in Fig. 3 for clarity.
For applications involving the use of UV light, a UV mask or UV projection can be used for spatial selectivity across the surface of the array. For applications involving electron beams, a focused electron beam writer or other electron beam source can be used for spatial selectivity. The exposure pattern imposed on the surface can be related to, or dictated by, underlying features in the film or on an underlying surface, or can be unrelated to such features. For example, when the underlying surface includes an electrode pattern, specific alignment of portions of the diblock exposure pattern with portions of the electrode pattern can be a requirement for device manufacture. The resulting array is referred to as being laterally patterned. Once a patterned nanoporous array template is created, surface-selective materials deposition methods can be used to locate desired materials into the pores to create nanoscale elements. Nanowires will be present only in areas which are the union of areas exposed to radiation, and areas containing an electrode underlying the surface of the copolymer film.
Novel use of electrochemical deposition methods, for example, enables several applications. Other surface-selective materials deposition techniques can be used, including chemical vapor deposition, electroless deposition, surface chemistry, chemical adsorption, and chemically driven layer-by-layer deposition, for example. hi the case of electrochemical deposition, different electrodes can be held at differing voltages during the electrochemical deposition to allow or prevent deposition at chosen electrodes, and this technique can be referred to as "programmed deposition." Specifically, since the underlying electrodes are separately addressable, one electrode (or group of electrodes) can be held at a potential appropriate for deposition of one material, while other electrodes are held at potentials which do not allow depositions of that material. This method offers expanded materials versatility, in that different types of nanowires can be deposited on the same chip.
An example of this type of nanofabrication is depicted in Fig. 4, which is a schematic diagram of a multilevel structure created using the concepts described above. In Fig. 4, the matrix component of the copolymer is deleted from view for clarity. The substrate includes thin film electrodes in, or on, its surface, which can be created by conventional lithography, for example. Lateral patterning can be carried out in registry with the underlying electrode pattern as desired, followed by electrodeposition of a first material, results in the creation of first nanowires, as shown. Subsequent electrodeposition of a second material, at an electrode potential different from that used for the electrodeposition of the first material results in the creation of second nanowires, as shown. First and second materials can differ in characteristics, particularly in characteristics which are relevant to the functional aspects of the devices. The first and second materials can be metals or semi-metals, so that characteristics, such as reduction potential, semi-metal type (for example, "n"- or "p"-type semi-metal, metalloid or semiconducting materials), reduction potential, and other useful characteristics can be varied in different locations of the film.
Alternatively, lateral patterning, followed by electrodeposition of a first material creates first nanowires as shown. Another lateral patterning step, in a different location, followed by electrodeposition of a second material, at any electrode potential, results in the creation of second nanowires. Subsequent lithography, also lαiown as electrodeposited post-level connections, on the surface of the film creates connections between sets of nanowires, and allows the creation of simple or complex circuits. Fig. 5 shows an overhead view of another example of such a three dimensional structure, emphasizing the relationship between electrical connections underlying (level #1), through (level #2), and overlying (level #3) the matrix component of the diblock copolymer to create electrical connections in registry with components on these differing levels.'
In some applications, it is desirable to use subsequent upper levels of lithography for interconnection and integration purposes. Such embodiments are depicted in Figs. 13 a, and 13b, which show two basic configurations of magneto- electronic transport nanodevices. Figs. 13a and 13b depict magneto-electronic device configurations that utilize transport current through the nanowires. These devices utilize anisotropic magnetoresistance, giant magnetoresistance, or spin-polarized current switching magnetoresistance, as discussed in Katine et al., "Current-driven magnetization reversal and spin-wave excitations in Co/Cu/Co pillars," Phys. Rev. Lett, 84> (2000), 3149, for magnetic sensing and "spintronic" purposes. They are relevant to magnetic data storage read head technology, magnetic RAM, and magnetic sensing applications. Fig. 13a shows a first configuration, in which the "current in" and "current out" electrodes are on the substrate level, and the interconnection between these two electrodes is on the upper interconnect level. Fig. 13b shows a second configuration, in which the "current in" electrode is on the substrate level and the "current out" electrode is on the upper interconnect level. Particular combinations of these configurations will be readily apparent to those designing circuits. A device of the construction depicted in Fig. 13 has been made, and a microscope photograph of this device is shown in Fig. 17. The patterned black regions are the locations of the nanowires. Magnetoresistance measurements of electron transport through the device depicted in Fig. 17 have been carried out, and are shown in Fig. 18. h addition, the nanowires themselves can be multilayered, using pulsed electrodeposition in a two-component bath, for example, to create Cu/Co multilayers, or by sequential electrodeposition. Some embodiments of multilayered nanowires are depicted in Fig. 13c. Magnetic nanowires are, as discussed above, created using magnetic materials, principally including cobalt, nickel, iron, and alloys containing these metals, and are useful for anisotropic magnetoresistance applications. Multilayered magnetic nanowires are created using substantially regularly alternating layers of magnetic materials and non-magnetic materials within individual nanowires (for example, Co/Cu alternating layers), and are useful for giant magnetoresistance applications. Asmmetric magnetic heterostructures are made using substantially nonregularly alternating layers of magnetic and non-magnetic materials, useful for spin-polarized current switching magnetoresistance.
Immediately after the selective area exposure, the polymer film contains polymer in three distinct states: 1) the degradation by-products; 2) the insoluble component; and 3) the virgin, oriented diblock copolymer in the unexposed regions. The coexistence of these three states offers additional fabrication versatility. By choice of solvent or radiation, one can choose to remove only the exposed cylinders, or alternatively, the exposed cylinders and the unexposed regions of diblock copolymer. For example, acetic acid can be used to remove degraded polymer fragments from the exposed area, but will not affect the matrix component. An agent such as acetic acid will also not remove material from the virgin, unexposed diblock copolymer. If desired, the removal of material from virgin regions can be achieved by treatment with another agent, for example, toluene. If desired, the removal of the unexposed diblock copolymer can be chosen to occur at a separate stage of processing, for example, after nanowires have been fabricated in the pores.
It is also relevant to note that for high-dosage over-exposures, both polymer blocks will crosslink, rendering a solid insoluble film that can also be used for fabrication purposes, hi such embodiments, neither component of the diblock copolymer can be removed. Such areas can be used as robust barriers, which protect the underlying substrate from further solvent processing. The use of different combinations of exposure and solvent protocols greatly advance the general utility of the general procedures described herein for the fabrication of nanostructures. hi data storage applications, patterning of magnetic arrays can be used to create patterned perpendicular magnetic media, as shown in Fig. 14a. Each set of nanowires is separated from other sets of nanowires by unexposed diblock copolymer. All individual nanowires within a given set of nanowires have the same magnetization direction, either up or down, corresponding to a data bit of either "1" or "0." In other applications in which the magnetic switching behavior of magnetic arrays can be exploited, the laterally patterned arrays described herein are of utility. The magnetization switching field of a magnetic nanowire can be modified substantially by the magnetic dipolar interactions it experiences due to neighboring nanowires, and consequently depends on whether the nanowire is found in a circle, triangle, cross- or star-shape, or other shape which tends to maximize or minimize the exposure of nanowires to each other or non-magnetic areas of the film. The lateral extent and shape of an array of magnetic nanowires will influence its switching behavior dramatically. This can be observed in the magnetic hysteresis curve (magnetization versus applied field) and in the magnetoresistance of a device using such wires. Using the patterned diblock templates we can create "designer micromagnetic media." This designer media can be used in magneto-transport device technologies that require discontinuous changes at specific threshold fields or for other applications that utilize step-wise changes in magnetic field. Some of such embodiments are exemplified in Fig. 14b, which show both triangular and circular sets of nanowires. The discontinuous switching behavior of designed devices can be enhanced for particular applications.
Applications
The three dimensional nanostnictured arrays described herein can be used in of technologies, including: display technology, cooling technology, magneto- electronic technology, data storage technology, sensor technology, biomoleciilar array technology, molecular electronic technology, waveguide technology, and other technologies. The techniques presented here are general and provide advances to a variety of research materials systems.
Field Emission Applications
Field emission displays (FEDs) offer high brightness, low power consumption, and flat-panel design. The displays can include an addressable array of field emitters and a phosphorescent screen. Efficient field emission displays require high-aspect-ratio nanoscale metal tips (for example, from about 20:1, or about 35:1, or about 50:1 to about 10,000:1) to enable electronic field emission at low tlireshold voltages. To achieve a sufficiently large current density, the emitters are desirably arranged into a high-density array. To define display pixels, the array is desirably patterned laterally into sets of nanowires, with each pixel electronically addressable. These sets can include from one to 10, 20, 30, or more nanowires, depending on the desired application.
The present invention offers simplified processing and the ability to make tip arrays with improved orientation.
The ultra-high density, laterally patterned arrays created by the methods described herein can be successfully used for high-resolution, low power, thin and flexible display devices. The high aspect ratio of nanowires created by the techniques described herein allow the tlireshold voltage for emission to be sufficiently low so that power consumption for such field emission devices is correspondingly lowered. The devices are useful for television and video screens, computer monitor screen, and many other display devices such as on watches, GPS devices, and any other devices currently using LED or LCD displays . The thinness of such field emission arrays allows the design of such devices to be far thinner than devices available currently. Display devices made with the technology described herein are also much brighter for a given level of energy consumption than those currently available. The possibility of using a flexible substrate further expands the utility of display devices made with the techniques described herein. Differing display applications will have differing priorities as regards operating characteristics; for example, an outdoor display can require high brightness, and a video display can require high resolution.
An example of a field emission array created according to the methods described herein is shown in Fig. 6, which is a perspective view of a diagram of such an array. The substrate has electrodes in or on its surface, created by conventional lithography. Diblock copolymer is deposited on the substrate, as described above, for example, by spin-bonding. Vertical orientation, selective irradiation, chemical treatment, and electrodeposition follow to create sets of nanowires, in this case, deposited on two distinct electrodes. For field emission applications, the ends of the nanowires are desirably at or near the film surface. This can be achieved by either growing (that is, electrodepositing) the wires to substantially the full film thickness, or by growing them to a lesser extent (for example, 90% of the film thickness), followed by removal of a portion of the surface of the film, by means known to those of skill in the art (including, for example, reactive ion etching by oxygen plasma). Again, the matrix component is deleted from Fig. 6 for clarity.
A device according to the construction of Fig. 6 was made, and microscope photographs of this device are shown in Fig. 19. The diblock template is shown patterned into a circular region at 20x magnification in the upper left of Fig. 19. The same region is shown after 250 nm cobalt nanowires have been grown at -IV into the circular region, but before electrical measurements were made at 20x magnification in the upper right of Fig. 19. The same region is shown after electrical measurements were made and then having brought up the emission current to the point at which the sample was destroyed in the lower part of Fig. 19 (lower left at 5x magnification, lower right at 20x magnification). Fig. 20 shows a graph of electronic field emission measurements made from the array shown in Fig. 19. A large current density and a low tlireshold was achieved. Fig. 21 is a close up of the images from Fig. 19, upper right and lower left, before and after destroying the sample, respectively.
The electrodes are individually addressable, in this case, with voltages Vi and V2. These applied voltages are independently varied as desired to control (that is, turn "on" and "off) the emission current from each nanowire set. A phosphor screen can be placed above the nanowire sets to create a display. Fig. 7 shows an overhead view of a similar device, but with four individually addressable sets of nanowires. It is important to note that nanowires are deposited only on the substrate where: 1) the copolymer is exposed to irradiation that degrades a component of the copolymer down to the substrate surface; 2) the residue of degraded component is removed from the substrate surface; and 3) the substrate surface has an electrical contact allowing electrodeposition.
Thermoelectric Cooling Applications
Solid-state cooling devices can also be designed utilizing the technology described herein. At present, the best commercially available theraioelectric cooling devices have theraioelectric figures of merit of approximately 0.1. The techniques described herein can produce devices which have thermoelectric figures of merit approaching or exceeding 2.0, e.g., devices having a figure of unit of 0.5, 0.7, 0.9, 1.0, 1.2, 1.5, 1.7, 1.8, 1.11, 2.0 or greater. Fig. 9 is a diagram of a single-stage thermoelectric cooler which can be made according to the methods described herein. The substrate has electrodes pre-pattemed in or on its surface. A patterned diblock copolymer layer is created on the substrate, as described herein. Again, the matrix component of the copolymer is deleted in Fig. 9 for clarity. Nanowires of two types are deposited by programmed electrodeposition. In the depicted example, "n-type" nanowires, made from "n-type" materials, well lαiown in the art, are deposited at one electrode, and "p-type" nanowires, made from "p-type" materials, also well known in the art, are deposited at another electrode. A top-layer metal interconnect is then deposited electrochemically. The device operates through the application of current through the device, so that the top plate becomes cold and the electrodes and substrate become warm. The top plate can be used as a heat sink for use in electronic devices, for example. Multistage coolers can also be made by this fabrication method. Heating devices are also made possible by the simple adaptation of the device for such purposes. Magnetic Data Storage Applications
Next generation magnetic data storage technologies will likely utilize perpendicular magnetic media to store data. Present technologies use lateral magnetic media in which the magnetic storage elements lie along the surface of the substrate. hi the effort of packing more elements per unit area, the size of the basic elements must be reduced. This introduces a problem, however, since as the scale of these regions is reduced, so is the blocking temperature which marks the onset of superparamagnetism. The blocking temperature must be kept large, otherwise the stored magnetization state of each element will decay and data will be lost. One way to reduce the size scale of a magnetic media element without substantially reducing the blocking temperature is to utilize shape and volume, that is, to make small cylindrically-shaped objects of high aspect ratio (for example, from about 20:1, or about 35:1 or about 50:1 to about 10,000:1). All other considerations being equal, a cylindrically-shaped magnet of diameter 10 nm and length of 500 nm will have a much higher blocking temperature than that of a spherical magnet of 10 nm diameter. The highest spatial packing density of magnetic cylinders occurs for cylinders in a vertical hexagonal closed-packed arrangement. hi the bulk, pure cobalt is a soft ferromagnet of relatively low coercivity and not necessarily an ideal material for magnetic data storage. However, certain cobalt alloys have "designer" magnetic properties including engineered coercivity which makes them useful for present-day magnetic media applications. These cobalt alloys can be electro-deposited from a specific plating bath containing the relevant ions.
The techniques described herein can be used to create arrays useful for the next generation of magnetic data storage. Since the surface smoothness of such arrays can be important, it is considered desirable to utilize an auxiliary polymer to produce highly smooth films on substrate surfaces. Highly smooth films can be created by depositing polydimethylsiloxane on a diblock copolymer film, as described in copending United States Patent Application Serial No. 09/814,891, filed March 22, 2001, titled "Nanocylinder Arrays." The application is incorporated herein by reference in its entirety. Engineered Magnetoresistance Applications
Magneto-electronic devices can be used for magnetic sensing applications (e.g., magnetic data storage) and for "spiiitronics" (e.g.,,MRAM). Appropriately chosen nanoscale magnetic architectures can result in improved performance since magnetic interactions can be tuned at the nanometer scale. The techniques described herein can be used to create devices in a variety of useful magneto-electronic configurations.
Materials have been developed over the last ten years that are now used for magnetic sensing by utilizing their giant magnetoresistive (GMR) properties. These materials have various architectures, but in general are multilayered materials with layers of non-magnetic metals in contact with layers of magnetic metals. The magnetic interlayer-exchange-coupling and electron spin-dependent scattering lead to the sensitivity of resistance with respect to magnetic field. Tuning the structure of these systems by materials engineering allows magnetoresistive properties to be optimized for applications. GMR read heads in hard-disk drive technology is one important commercial application. These engineered materials systems are expected to advance with better materials and new material architectures.
The magnetic arrays made using techniques described herein show GMR type behavior. However, the architecture of these arrays is significantly different than others that have been produced. The important consideration for GMR device design is that there be electrical contact between the substrate and the magnetic nanowires, not whether the wires are embedded in the template or not. Therefore, the wires can be grown (that is, electrodeposited) to less than the film thickness for GMR devices without a need to remove matrix material prior to operability. Of key importance to optimal performance of GMR devices is the ability to form a regular array of very small dimensions, for example, an array of 25.4 nanometer period made of cylinders 11 nanometers in diameter. Furthermore the fabrication processes described herein permit the well-controlled height of the cylinders, and the ability to multilayer the cylinder material as it is grown. These new processing considerations have allowed the creation of new geometrical arcliitectures at size scales that have not been achieved using known fabrication processes. By tuning material structure in the fabrication processes described herein, a new breed of GMR materials is possible.
A particular embodiment of a GMR device is shown in Fig. 10. The device is created by fabricating a ma netic nanoarray as described herein on a substrate patterned with an electrode. This particular magnetoresistive device is in a "lateral transport" configuration (the transport current is affected by the presence of the magnetic nanowires, but is not configured to pass through the wire along its length). Again, the matrix component of the copolymer is deleted from Fig. 10 for clarity. The nanowires for such a device are desirably asymmetric magnetic hetero structures, as described above with respect to Fig. 13c. Fig. 13c does not imply that in a given set of nanowires, all three types are used, rather that any one of the types can be employed in a set.
Smart Media Applications "Smart media" are media that sense this environment in a particular way, and create a measurable response. This could be, for example, a chemical sensor in which the device produces an electrical current when the presence of a particular type of molecule in solution is detected. Any electrical version of patterned smart media could be integrated with other signal processing on the same chip. Another example is a sensing medium that changes color upon sensing a change in chemical environment, temperature environment, optical stimulus, or other type of stimulus. Since the diblock systems are laterally patterned, arrays with large numbers of distinct sensing elements are fabricated. Each element is a localized transducer that is integrated into an on-chip circuit. Presently, the techniques described herein can be used to produce nanowire
1 9 arrays with a nanoelement density of approximately 1.2 x 10 elements/in . This ultimately enables data storage technologies with storage capacities exceeding a terabit/in2. Patterned versions of high-density media in which one bit of data is encoded in the magnetization of a group of magnetic nanowires are created. The patterned diblock-derived devices described herein provide a simple fabrication route to high storage densities. Electrochemical Sensor Applications
These sensors are used in a wide range of applications, including portable glucose detection for people with diabetes. The nanoporous templates disclosed herein are used conveniently to make devices for electrochemical sensing as an array of "microelectrodes." In the electrochemistry literature the term "microelectrode" refers to a configuration of electrode that induces radial diffusion of an electrochemically-active species toward the electrode. The behavior of a microelectrode differs dramatically from that of a planar electrode. A nanoporous polymer template nanoelectrode array as described herein offers fast response, lower detection limits, and the possibility for molecular selectivity based on size or molecular interactions with the template. The lateral-patterning invention advances the use of nanoporous templates for this purpose because several distinct microelectrodes arrays are configured onto the same chip using patterned diblock templates atop a pre-patterned thin-film electrode set.
Biomolecule Array Applications
Combinatorial chips are configured for DNA gene expression studies and other diagnostic applications. The nanoporous polymer templates described herein are patterned and filled with metals or silicon oxide that are used to attach biomolecules that will enable new types of biomolecular research capabilities. Patterned versions of such structures are of far greater usefulness. Another application for lateral patterning is to create structures for sorting molecules in nanoscales.
Molecular Electronics Applications
Specific types of molecules and small colloidal clusters are used as electronic devices. The goal is to "design in" electronic functionality (e.g., rectification, switcl ing, negative differential resistance) by synthesizing molecules using certain types of end groups, aromatic rings and side groups. Interfacing these molecules for electrical characterization using known techniques is extremely challenging. However, new patterned nanoporous templates can be used as a practical host substrate for the characterization of specific types of electronically relevant molecules. The diblock template is patterned in regions atop pre-pattemed gold electrodes. The molecules are adsorbed to the gold at the bottom. of each pore using a thiol-gold interaction. This results in a self-assembled moiiolayer of the electronic molecules at the bottom of each pore. A counter electrode is deposited electrochemically atop the molecular layer and contacted using the patterned interconnections described above. This fabrication scheme enables convenient electrical characterization of candidate molecules.
Photonic-bandgap Structure Applications
A photonic-bandgap crystal is a optical material that has periodically modulating dielectric constant. As a consequence of the periodic structure, the transmission properties become dependent on the incident light frequency such that certain frequencies, there is no transmission (the dispersion relation Q(k) is non- linear and has derivative of zero at Brillouin zone boundaries, k = Ula, where a is the crystal lattice period). Using these materials, a range of devices can be configured in analogy to electronic devices. Once diblock copolymer systems can be made with a sufficiently long-range array order, they can be patterned in specific shapes to fabricate planar photonic-crystal waveguides and other photonic-crystal devices.
Photonic waveguides are able to have much smaller turn radius as compared to optical fiber. Such waveguides can be used to interconnect on-chip optical components.
Electrical Interconnections to Nanowires Electrical interconnections can be made to nanowires made by patterned diblock copolymer templates. This is achieved by integrating the templating process with other pre- and post-processing steps.
An important step in utilizing electrical nanostructures is making appropriate electrical interfaces to these nanostructures. hi Figure 15, one embodiment of the present invention is realized. First, electrodes are prepattemed onto the substrate by a suitable lithographic technique. Secondly, a diblock copolymer film is deposited. Next, a metal layer is deposited. Finally, a conventional (photo- or e-beam-) resist is deposited. The cylinders of the diblock copolymer can be oriented by the techniques described herein. The resulting structure is shown in Fig. 15 a. Selected areas of the top resist are exposed lithographically and removed by chemical development. Subsequently the exposed metal layer (#2) is removed by a metal etch. At this point the diblock film is exposed to ultraviolet (UV) light or an electronic beam, if it has not been exposed in a prior step. This structure is shown in Fig. 15b. The diblock film is now chemically developed with acetic acid or another suitable developer to result in a nanoporous template. If desired, the surface of the nanoporous template can be cleaned using a reactive ion etch with oxygen. This structure is shown in Fig. 15c.
Nanowires or other suitable nanostructures are now deposited into the pores of the nanoporous template. To achieve top electrical contact, the deposition can continue until electrical connection is made with the top layer. As discussed herein, a range of different desired nanostructures^ can be deposited in the pores, depending on the target application. This structure is shown in Fig. 15d. hi some applications, such as field emissions arrays, electrical contact to the top layer is not desired. Rather, the isolated top metal layer would be used as an electrical gate in a triode field emission device configuration. In other applications, metal contact #2 can be replaced over the deposited nanowires to complete contact through the wires, as shown in Fig. 15e.
The integration scheme described in Figure 15 represents only one out of several schemes for integration and interfacing nanostructures made by patterned nanoporous templates. Nanofabrication via patterned diblock copolymers can be combined easily with other (pre- and post-) process steps, and done so such that the pattern is made in registry with previous lithographic patterns.
Another fabrication scheme can be described as follows. First, electrodes are prepattemed onto the substrate by a suitable lithographic technique. Secondly, a diblock copolymer film is deposited. The diblock cyclinders are then oriented , exposed lithographically in a desired pattern, and then developed into a nanoporous template. Nanowires or other suitable nanostructures are now deposited mto the pores of the nanoporous template. , To achieve top electrical contact, or top non-contact electrodes, a suitable lithographic exposure and development, a ion etch performed to remove degraded portions (for example, oxide) from the top of the nanowires, and then deposition of metal electrodes in the contact areas.
The following examples do not limit the scope of the invention described in the claims.
EXAMPLES
The following examples illustrate particular properties and advantages of some of the embodiments.
Example 1 : A Prototype of a Field Emission Array
Figs. 8a-8d are 10X optical images of a prototype of a field emission array built by the inventors. In Fig. 8a, the silicon substrate was gold patterned with conventional lithography with a 1 micrometer thick, vertically oriented diblock copolymer film (polystyrene/polymethylmethacrylate, 70/30 by volume) covering the entire surface (the film is optically transparent). Fig. 8b is an image of the same sample after electron-beam patterning in the shape of a square, and acetic acid development. The inner square was a patterned nanoporous template. The outer square was a solid film of crosslinked polystyreiie/polymethylmethacrylate made by intentional overexposure to radiation. Fig. 8c is an image of the same sample after
500 nm length cobalt wires were electrodeposited in the template. The cobalt is black in the image. Fig. 8d is a close-up of the electrodeposited area. It is important to note that the nanowires deposit only in the nanoporous template regions with metal underneath. Example 2: A Prototype Magnetoresistive Device
Figs. 11a and lib are 10X optical images of a prototypical four- wire magnetoresistive device made by the inventors. An array of vertical magnetic nanowires stands atop a thin-film of gold pre-patterned into a four-probe resistor pattern. This device is used to investigate spin-dependent scattering in a "current-in- plane" (CIP) geometry where the scattering interface is geometrically periodic on the scale of tens of nanometers. Fig. 1 la is an image of a substrate with a patterned electrode underlayer covered with an optically transparent diblock copolymer film layer prepared as described in Example 1. The four probe resistor pattern was created as 2 μm in width and 100 μm in length, by standard electron beam lithography using a PMMA resist on a silicon substrate. The thin-film resistor includes a 20 nm thick gold layer on top of a 1 nm Cr adhesion layer. A 1.1 μm thick film of poly(styrene-β-methylmethacrylate) diblock copolymer denoted P(S-β-MMA) having 30% by volume polymethylmethacrylate (PMMA) with molecular weight of 42,000 Daltons was spun coated onto the patterned surface of substrate. This copolymer microphase separates into a hexagonal array of PMMA cylinders in a polystyrene (PS) matrix. Annealing thin films at 180°C, above the glass transition temperature under an applied electric field, orients the PMMA cylinders normal to the film surface, enabling the fabrication of nanostructures with large aspect ratios. The sample was then exposed to an electron beam impinging on the sample in the shape of a square (area dose of 50 μC/cm2, with beam energy and current used is 20 kV and 2000 pA, respectively. Generally, for such diblock films of about 1 micron, the exposure dose can range from about 20 to about 200 μC/cm , with accelerating voltages and beam currents as described above. Optimal doses have been found to be about 80 μC/cm2. The sample was then chemically developed with acetic acid. The original copolymer remains in the unexposed areas.
Cobalt nanowires were deposited in the pores on top of the gold pattern from an aqueous deposition bath, prepared by mixing 96 grams of CoSO -7H2O and 13.5 grams H3BO3 in 300 ml pure H2O, with 60 ml of methanol added as surfactant, resulting in an electrolyte pH of 3.7. The Co was electroplated at a reduction potential of -1.0V with respect to a saturated calomel reference electrode. The nanowires were 500 nm in length. Fig. lib is an image of the same sample after nanowire electrodeposition.
Structural information was obtained by performing small angle X-ray scattering (SAXS) and field emission scanning electron microscopy (FESEM). The SAXS data confirms a perpendicular nanowire orientation with a period of 21.7 nm. The sample was cleaved in two, and FESEM used to examine a cross-section of the nanowire array. The diameter of the nanowires was found to be approximately 11 nm, with a period of 21.8 nm. At this scale, the individual magnetic nanowires should be single-domain in equilibrium, and show interesting magnetoresistance (MR) effects, since the interwire spacing is less than the spin diffusion length.
Example 3 : Giant Magnetoresistance Device and Measurements
The four- wire magnetoresistive device prepared in Example 2 was used for measurement. The magnetic cobalt nanowire array is composed of 14 nm diameter wires, each 500 nm long, arranged in a hexagonal lattice with a period of 24 nm. The structure of the device was verified by small-angle X-ray scattering measurements. The magnetic field direction is parallel to the nanowire axis. A cross sectional scamiing electron micrograph (SEM) image of such an array is shown in Fig. 12b. The GMR ratio as a function of temperature between 2K and 300K is shown in Fig. 12a. The data taken at 2K shows the largest amplitude curve, and that taken at 300K shows the smallest amplitude curve, with intermediate temperatures having intermediate values, with amplitudes in line with the ordering of the temperature.
Other GMR ratios, as a function of orientation of magnetic field and temperature are shown in Figs. 16a-c. The magnetoresistance is defined as [R(H) - R(50 kOe)/R(50 kOe)]. Again, the data taken at 2K shows the largest amplitude curve, and that taken at 300K shows the smallest amplitude curve, with intermediate temperatures having intermediate values, with amplitudes in line with the ordering of the temperature. In the "perpendicular" orientation (fig. 16a), the field is normal to the plane of the Au film (parallel to the Co nanowires) and the current direction. For the "transverse" orientation (Fig. 16b) and "longitudinal" orientation (Fig. 16c), the field is in the plane of the gold film (perpendicular to the Co wires), but perpendicular or parallel to the current direction, respectively. The different shapes and values for the MR curves for the three orientations provide evidence for the coexistence of anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR) scattering mechanisms in this system.
MR behavior of the Co nanowires was also investigated as a function of gold film thickness and Co nanowire length. Gold films of 7.5, 10 and 20 nm thickness were studied with Co nanowires of 500 nm. Also, samples of Co nanowire lengths of 100 and 500 nm were prepared having gold film thickness of 20 nm. MR behavior was found to depend principally on nanowire length. A plot of noraialized MRmax for a perpendicular orientation at 0 field versus temperature for various gold film thicknesses and Co nanowire lengths is shown in Fig. 22. The characteristics clearly indicate that the temperature dependence of MR is strongly dependent on the Co nanowire length, but not so strongly on the gold film thickness. Each data set is normalized to its 2K value for comparison.
OTHER EMBODIMENTS
It is to be understood that while the invention has been described in conjunction with the detailed description thereof, that the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.

Claims

What is claimed is:
1. A multilayer nanostructure comprising: a substrate surface, at least a portion of which is conductive or semiconductive; and at least one set of nanowires extending from the conductive or semiconductive substrate surface, wherein one end of the nanowires is in electrical communication with the conductive or semiconductive surface.
2. The multilayer nanostructure of claim 1, further comprising at least one conductive or semiconductive layer contacting an opposite end of at least some of the nanowires in the set, wherein the conductive or semiconductive layer is in electrical communication with at least some of the nanowires in the set.
3. The multilayer nanostructure of claim 1 , wherein the set comprises nanowires having substantially the same length.
4. The multilayer nanostructure of claim 3, wherein the set comprises nanowires having length of at least 20 nm.
5. The multilayer nanostructure of claim 4, wherein the set comprises nanowires having length of at least 100 nm.
6. The multilayer nanostructure of claim 1, wherein the substrate is lithographically patterned, having a plurality of independently conductive or semiconductive surface regions.
7. The multilayer nanostructure of claim 6, wherein at least one set is in electrical communication with a plurality of independently conductive or semiconductive surface regions.
8. The multilayer nanostructure of claim 6, wherein at least some independently conductive or semiconductive surface regions are each in electrical coimrmnication with an individual set of nanowires.
9. The multilayer nanostructure of claim 2, wherein the substrate is lithographically patterned, having a plurality of independently conductive or semiconductive surface regions.
10. The multilayer nanostructure of claim 9, wherein at least one set is in electrical communication with a plurality of independently conductive or semiconductive surface regions.
11. The multilayer nanostructure of claim 9, wherein at least some independently conductive or semiconductive surface regions are each in electrical communication with individual sets of nanowires.
12. The multilayer nanostructure of claim 11 , wherein the conductive or semiconductive layer is in electrical communication with at least some of the nanowires in a plurality of sets.
13. The multilayer nanostructure of claim 2, comprising a plurality of the conductive or semiconductive layers.
14. The multilayer nanostructure of claim 13, wherein at least some conductive or semiconductive layers are each in electrical communication with at least some nanowires in a plurality of sets.
15. The multilayer nanostructure of claim 11, wherein at least some sets comprise nanowires made of material distinct from that of other sets.
16. The multilayer nanostructure of claim 15 , wherein nanowires differ in their reduction potential.
17. The multilayer nanostructure of claim 15, wherein nanowires differ in their semi-metal type.
18. The multilayer nanostructure of claim 1 , wherein at least some nanowires comprise magnetic material.
19. The multilayer nanostructure of claim 1, wherein at least some nanowires are multilayered.
20. The multilayer nanostructure of claim 19, wherein at least some nanowires are multilayered.
21. The multilayer nanostructure of claim 11 , wherein at least some sets can be modified to have magnetic properties distinct from those of other sets.
22. The multilayer nanostructure of claim 21 , wherein the magnetic properties comprise magnetization direction.
23. A field emission display device comprising: an addressable array of field emitters comprising a multilayer nanostructure of claim 12; and a phosphorescent screen.
24. A thermoelectric cooling device comprising: a multilayer nanostructure of claim 17, comprising nanowires of "n-" and "p-" types.
25. A magnetic data storage device comprising: a multilayer nanostructure of claim 21, wherein the nanowires have an aspect ratio of at least 20:1.
26. A magneto-electronic device comprising: a multilayer nanostructure of claim 12, wherein the nanowires comprise magnetic material.
27. The magneto-electronic device of claim 26, wherein the nanowires comprise asymmetric magnetic heterostructure.
28. A method of interfacing an electrical connection with a multilayer nanostructure, the method comprising: preparing a diblock copolymer on a substrate surface, at least a portion of which is conductive or semiconductive; depositing a metal layer on at least a portion of the diblock copolymer layer; orienting the diblock copolymer to form nanoscopic cylinders parallel to each other and vertically oriented with respect to the surface; removing at least a portion of one component from the oriented copolymer to form a patterned array of nanopores in the copolymer; and at least partially filling at least some of the nanopores with a material.
29. The method of claim 28, further comprising depositing a resist layer on at least a portion of the metal layer prior to orienting the copolymer.
30. The method of claim 28, wherein the removal of at least a portion of one component from the oriented copolymer is performed by exposure to radiation.
31. The method of claim 28, wherein the material used to at least partially fill at least some of the nanopores comprises magnetic material.
32. A magnetotransfer device comprising: a substrate surface comprising at least one electrode; an array of magnetic nanowires extending vertically from the surface in electrical communication with at least one electrode, wherein the array of nanowires is periodic on the tens of nanometers scale.
33. The device of claim 32, wherein the interwire spacing in the array is substantially regular.
34. The device of claim 33, wherein the interwire spacing is less than the spin diffusion length.
PCT/US2002/007769 2001-03-14 2002-03-14 Nanofabrication WO2002073699A2 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA002451882A CA2451882A1 (en) 2001-03-14 2002-03-14 Nanofabrication
KR1020037012051A KR100878281B1 (en) 2001-03-14 2002-03-14 Nanofabrication
EP02725158A EP1374310A4 (en) 2001-03-14 2002-03-14 Nanofabrication
JP2002572644A JP2004527905A (en) 2001-03-14 2002-03-14 Nano manufacturing

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US27598401P 2001-03-14 2001-03-14
US60/275,984 2001-03-14

Publications (3)

Publication Number Publication Date
WO2002073699A2 true WO2002073699A2 (en) 2002-09-19
WO2002073699A3 WO2002073699A3 (en) 2002-11-14
WO2002073699A9 WO2002073699A9 (en) 2004-05-06

Family

ID=23054638

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2002/007769 WO2002073699A2 (en) 2001-03-14 2002-03-14 Nanofabrication

Country Status (6)

Country Link
US (2) US7189435B2 (en)
EP (1) EP1374310A4 (en)
JP (1) JP2004527905A (en)
KR (1) KR100878281B1 (en)
CA (1) CA2451882A1 (en)
WO (1) WO2002073699A2 (en)

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004056699A2 (en) * 2002-12-20 2004-07-08 Leibniz-Institut Für Polymerforschung Dresden E.V. Nanoparticles, nanoscopic structures and method for production thereof
WO2005054119A3 (en) * 2003-12-01 2005-10-13 Univ Illinois Methods and devices for fabricating three-dimensional nanoscale structures
WO2007133894A2 (en) * 2006-05-12 2007-11-22 General Electric Company Low dimensional thermoelectrics fabricated by semiconductor wafer etching
WO2008054854A2 (en) * 2006-05-31 2008-05-08 General Electric Company Thermoelectric nanotube arrays
WO2008060282A1 (en) * 2006-11-17 2008-05-22 General Electric Company Thermal transfer and power generation devices and methods of making the same
JP2008189543A (en) * 2007-01-03 2008-08-21 Toyota Motor Engineering & Manufacturing North America Inc Method of non-catalytic formation and growth of nanowires
WO2011074852A1 (en) * 2009-12-18 2011-06-23 Korea University Research And Business Foundation Use of block copolymers for preparing conductive nanostructures
US8039726B2 (en) 2005-05-26 2011-10-18 General Electric Company Thermal transfer and power generation devices and methods of making the same
US8101449B2 (en) 2007-01-03 2012-01-24 Toyota Motor Engineering & Manufacturing North America, Inc. Process for altering thermoelectric properties of a material
US8354459B2 (en) 2009-08-18 2013-01-15 Japan Science And Technology Agency Method for producing polymer material
US8558311B2 (en) 2004-09-16 2013-10-15 Nanosys, Inc. Dielectrics using substantially longitudinally oriented insulated conductive wires
TWI469183B (en) * 2007-02-08 2015-01-11 Micron Technology Inc Methods using block copolymer self-assembly for sub-lithographic patterning
US9629586B2 (en) 2008-10-07 2017-04-25 Mc10, Inc. Systems, methods, and devices using stretchable or flexible electronics for medical applications
US9647171B2 (en) 2009-05-12 2017-05-09 The Board Of Trustees Of The University Of Illinois Printed assemblies of ultrathin, microscale inorganic light emitting diodes for deformable and semitransparent displays
US9691873B2 (en) 2011-12-01 2017-06-27 The Board Of Trustees Of The University Of Illinois Transient devices designed to undergo programmable transformations
US9723122B2 (en) 2009-10-01 2017-08-01 Mc10, Inc. Protective cases with integrated electronics
US9761444B2 (en) 2004-06-04 2017-09-12 The Board Of Trustees Of The University Of Illinois Methods and devices for fabricating and assembling printable semiconductor elements
US9765934B2 (en) 2011-05-16 2017-09-19 The Board Of Trustees Of The University Of Illinois Thermally managed LED arrays assembled by printing
US9936574B2 (en) 2009-12-16 2018-04-03 The Board Of Trustees Of The University Of Illinois Waterproof stretchable optoelectronics
US9986924B2 (en) 2010-03-17 2018-06-05 The Board Of Trustees Of The University Of Illinois Implantable biomedical devices on bioresorbable substrates
US10052066B2 (en) 2012-03-30 2018-08-21 The Board Of Trustees Of The University Of Illinois Appendage mountable electronic devices conformable to surfaces
US10349860B2 (en) 2011-06-03 2019-07-16 The Board Of Trustees Of The University Of Illinois Conformable actively multiplexed high-density surface electrode array for brain interfacing
US10350794B2 (en) 2013-10-31 2019-07-16 University Of Florida Research Foundation, Inc. Porous polymer membranes, methods of making, and methods of use
US10441185B2 (en) 2009-12-16 2019-10-15 The Board Of Trustees Of The University Of Illinois Flexible and stretchable electronic systems for epidermal electronics
US10717108B2 (en) 2014-10-17 2020-07-21 University Of Florida Research Foundation, Inc. Methods and structures for light regulating coatings
RU199472U1 (en) * 2020-06-25 2020-09-02 Федеральное государственное автономное образовательное учреждение высшего образования "Национальный исследовательский университет ИТМО" PHOTOSENSOR BASED ON A FLEXIBLE MEMBRANE WITH FILAMENT NANOCRYSTALS
US10808095B2 (en) 2015-05-08 2020-10-20 University Of Florida Research Foundation, Inc. Macroporous photonic crystal membrane, methods of making, and methods of use
US10918298B2 (en) 2009-12-16 2021-02-16 The Board Of Trustees Of The University Of Illinois High-speed, high-resolution electrophysiology in-vivo using conformal electronics
US10925543B2 (en) 2015-11-11 2021-02-23 The Board Of Trustees Of The University Of Illinois Bioresorbable silicon electronics for transient implants
US11029198B2 (en) 2015-06-01 2021-06-08 The Board Of Trustees Of The University Of Illinois Alternative approach for UV sensing
US11118965B2 (en) 2015-06-01 2021-09-14 The Board Of Trustees Of The University Of Illinois Miniaturized electronic systems with wireless power and near-field communication capabilities
US11467094B2 (en) 2017-05-17 2022-10-11 University Of Florida Research Foundation, Inc. Methods and sensors for detection
US11480527B2 (en) 2017-12-20 2022-10-25 University Of Florida Research Foundation, Inc. Methods and sensors for detection
US11705527B2 (en) 2017-12-21 2023-07-18 University Of Florida Research Foundation, Inc. Substrates having a broadband antireflection layer and methods of forming a broadband antireflection layer
US11795281B2 (en) 2016-08-15 2023-10-24 University Of Florida Research Foundation, Inc. Methods and compositions relating to tunable nanoporous coatings
US11819277B2 (en) 2018-06-20 2023-11-21 University Of Florida Research Foundation, Inc. Intraocular pressure sensing material, devices, and uses thereof

Families Citing this family (245)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001070873A2 (en) * 2000-03-22 2001-09-27 University Of Massachusetts Nanocylinder arrays
EP1314189B1 (en) 2000-08-22 2013-02-27 President and Fellows of Harvard College Electrical device comprising doped semiconductor nanowires and method for its production
AU2904602A (en) 2000-12-11 2002-06-24 Harvard College Nanosensors
US7084507B2 (en) * 2001-05-02 2006-08-01 Fujitsu Limited Integrated circuit device and method of producing the same
US7098393B2 (en) * 2001-05-18 2006-08-29 California Institute Of Technology Thermoelectric device with multiple, nanometer scale, elements
EA003573B1 (en) * 2001-06-29 2003-06-26 Александр Михайлович Ильянок Self-scanning flat display
US7186381B2 (en) * 2001-07-20 2007-03-06 Regents Of The University Of California Hydrogen gas sensor
GB0207307D0 (en) * 2002-03-27 2002-05-08 Koninkl Philips Electronics Nv In-pixel memory for display devices
US20040026684A1 (en) * 2002-04-02 2004-02-12 Nanosys, Inc. Nanowire heterostructures for encoding information
US6872645B2 (en) * 2002-04-02 2005-03-29 Nanosys, Inc. Methods of positioning and/or orienting nanostructures
US6548313B1 (en) * 2002-05-31 2003-04-15 Intel Corporation Amorphous carbon insulation and carbon nanotube wires
US8294025B2 (en) 2002-06-08 2012-10-23 Solarity, Llc Lateral collection photovoltaics
US6946851B2 (en) * 2002-07-03 2005-09-20 The Regents Of The University Of California Carbon nanotube array based sensor
US7335908B2 (en) * 2002-07-08 2008-02-26 Qunano Ab Nanostructures and methods for manufacturing the same
AU2003302019A1 (en) 2002-08-23 2004-06-15 The Regents Of The University Of California Improved microscale vacuum tube device and method for making same
US6858521B2 (en) * 2002-12-31 2005-02-22 Samsung Electronics Co., Ltd. Method for fabricating spaced-apart nanostructures
US6864162B2 (en) * 2002-08-23 2005-03-08 Samsung Electronics Co., Ltd. Article comprising gated field emission structures with centralized nanowires and method for making the same
US7012266B2 (en) 2002-08-23 2006-03-14 Samsung Electronics Co., Ltd. MEMS-based two-dimensional e-beam nano lithography device and method for making the same
JP4304947B2 (en) * 2002-09-26 2009-07-29 株式会社日立製作所 Magnetic recording medium, magnetic memory device using the same, magnetic recording method, and signal reproduction method
US20050079282A1 (en) * 2002-09-30 2005-04-14 Sungho Jin Ultra-high-density magnetic recording media and methods for making the same
US7196386B2 (en) * 2002-10-03 2007-03-27 Sony Corporation Memory element and memory device
TWI220162B (en) * 2002-11-29 2004-08-11 Ind Tech Res Inst Integrated compound nano probe card and method of making same
US7001669B2 (en) 2002-12-23 2006-02-21 The Administration Of The Tulane Educational Fund Process for the preparation of metal-containing nanostructured films
WO2004076344A2 (en) * 2003-02-25 2004-09-10 Yeda Research And Development Company Ltd. Nanoscopic structure and devices using the same
US6918284B2 (en) * 2003-03-24 2005-07-19 The United States Of America As Represented By The Secretary Of The Navy Interconnected networks of single-walled carbon nanotubes
US7741033B2 (en) * 2003-05-13 2010-06-22 Trustees Of Boston College Electrocatalytic nucleic acid hybridization detection
US20060124467A1 (en) * 2003-05-20 2006-06-15 Industrial Technology Research Institute Metal nanodot arrays and fabrication methods thereof
US7265037B2 (en) * 2003-06-20 2007-09-04 The Regents Of The University Of California Nanowire array and nanowire solar cells and methods for forming the same
US6921670B2 (en) * 2003-06-24 2005-07-26 Hewlett-Packard Development Company, Lp. Nanostructure fabrication using microbial mandrel
KR100571812B1 (en) * 2003-07-19 2006-04-17 삼성전자주식회사 patterned magnetic recording media and manufacturing method thereof
US7344753B2 (en) * 2003-09-19 2008-03-18 The Board Of Trustees Of The University Of Illinois Nanostructures including a metal
US8030833B2 (en) * 2003-09-19 2011-10-04 The Board Of Trustees Of The University Of Illinois Electron emission device incorporating free standing monocrystalline nanowires
FR2860780B1 (en) * 2003-10-13 2006-05-19 Centre Nat Rech Scient METHOD FOR SYNTHESIS OF NANOMETRIC FILAMENT STRUCTURES AND COMPONENTS FOR ELECTRONICS COMPRISING SUCH STRUCTURES
US6969679B2 (en) * 2003-11-25 2005-11-29 Canon Kabushiki Kaisha Fabrication of nanoscale thermoelectric devices
US7181836B2 (en) * 2003-12-19 2007-02-27 General Electric Company Method for making an electrode structure
US7553371B2 (en) * 2004-02-02 2009-06-30 Nanosys, Inc. Porous substrates, articles, systems and compositions comprising nanofibers and methods of their use and production
US20110039690A1 (en) * 2004-02-02 2011-02-17 Nanosys, Inc. Porous substrates, articles, systems and compositions comprising nanofibers and methods of their use and production
US8025960B2 (en) * 2004-02-02 2011-09-27 Nanosys, Inc. Porous substrates, articles, systems and compositions comprising nanofibers and methods of their use and production
US6930322B1 (en) * 2004-03-26 2005-08-16 Matsushita Electric Industrial Co., Ltd. Combination insulator and organic semiconductor formed from self-assembling block co-polymers
JP4005983B2 (en) * 2004-04-15 2007-11-14 憲司 中村 Antibacterial cosmetic equipment and method for producing the same
US20060013956A1 (en) * 2004-04-20 2006-01-19 Angelescu Dan E Method and apparatus for providing shear-induced alignment of nanostructure in thin films
US20050279274A1 (en) * 2004-04-30 2005-12-22 Chunming Niu Systems and methods for nanowire growth and manufacturing
CA2564220A1 (en) * 2004-04-30 2005-12-15 Nanosys, Inc. Systems and methods for nanowire growth and harvesting
US7785922B2 (en) 2004-04-30 2010-08-31 Nanosys, Inc. Methods for oriented growth of nanowires on patterned substrates
US7625694B2 (en) * 2004-05-06 2009-12-01 Micron Technology, Inc. Selective provision of a diblock copolymer material
US20050257821A1 (en) * 2004-05-19 2005-11-24 Shriram Ramanathan Thermoelectric nano-wire devices
JP2008506212A (en) * 2004-07-06 2008-02-28 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ Optical head having variable optical element
WO2006016914A2 (en) * 2004-07-07 2006-02-16 Nanosys, Inc. Methods for nanowire growth
US20060024438A1 (en) * 2004-07-27 2006-02-02 The Regents Of The University Of California, A California Corporation Radially layered nanocables and method of fabrication
US7365395B2 (en) * 2004-09-16 2008-04-29 Nanosys, Inc. Artificial dielectrics using nanostructures
US8089152B2 (en) * 2004-09-16 2012-01-03 Nanosys, Inc. Continuously variable graded artificial dielectrics using nanostructures
JP4707995B2 (en) * 2004-11-05 2011-06-22 富士フイルム株式会社 Ordered nanostructured materials
TWI287805B (en) * 2005-11-11 2007-10-01 Ind Tech Res Inst Composite conductive film and semiconductor package using such film
KR20070101857A (en) 2004-12-06 2007-10-17 더 프레지던트 앤드 펠로우즈 오브 하바드 칼리지 Nanoscale wire-based data storage
US20060134392A1 (en) * 2004-12-20 2006-06-22 Palo Alto Research Center Incorporated Systems and methods for electrical contacts to arrays of vertically aligned nanorods
US7202173B2 (en) * 2004-12-20 2007-04-10 Palo Alto Research Corporation Incorporated Systems and methods for electrical contacts to arrays of vertically aligned nanorods
US7697391B2 (en) * 2004-12-20 2010-04-13 Emc Corporation Massively multi-level optical data storage using subwavelength sized nano-grating structures
US8178165B2 (en) * 2005-01-21 2012-05-15 The Regents Of The University Of California Method for fabricating a long-range ordered periodic array of nano-features, and articles comprising same
US7008853B1 (en) * 2005-02-25 2006-03-07 Infineon Technologies, Ag Method and system for fabricating free-standing nanostructures
US20090270266A1 (en) * 2005-04-12 2009-10-29 Kelley Shana O Method for Electrocatalytic Protein Detection
KR100612894B1 (en) * 2005-05-02 2006-08-14 삼성전자주식회사 Nanowire device and fabrication method of the same
FR2885913B1 (en) * 2005-05-18 2007-08-10 Centre Nat Rech Scient COMPOSITE ELEMENT COMPRISING A CONDUCTIVE SUBSTRATE AND A NANOSTRUCTURED METAL COATING.
US20100227382A1 (en) 2005-05-25 2010-09-09 President And Fellows Of Harvard College Nanoscale sensors
WO2006132659A2 (en) 2005-06-06 2006-12-14 President And Fellows Of Harvard College Nanowire heterostructures
CN100417117C (en) * 2005-06-15 2008-09-03 华为技术有限公司 Method for recognizing node accessibility in automatically switched optical network
US20060286906A1 (en) * 2005-06-21 2006-12-21 Cabot Microelectronics Corporation Polishing pad comprising magnetically sensitive particles and method for the use thereof
WO2007008088A1 (en) * 2005-07-08 2007-01-18 Nano Cluster Devices Ltd Nanoscale and microscale lithography methods and resultant devices
KR101155176B1 (en) * 2005-07-12 2012-06-11 삼성전자주식회사 Fabrication method of orientation controlled simgle-crystalline wire and transistor adopting the wire
WO2007038381A2 (en) * 2005-09-23 2007-04-05 Soligie, Inc. Screen printing using nanoporous polymeric membranes and conductive inks
US20070187238A1 (en) * 2005-09-29 2007-08-16 Whalen John J Iii Microelectrode system for neuro-stimulation and neuro-sensing and microchip packaging
WO2007041293A2 (en) * 2005-09-29 2007-04-12 Doheny Eye Institute Microelectrode systems for neuro-stimulation and neuro-sensing and microchip packaging and related methods
WO2007055041A1 (en) * 2005-11-10 2007-05-18 National University Corporation Kyoto Institute Of Technology Membrane of block copolymer with oriented cylinder structure and process for producing the same
US7371674B2 (en) * 2005-12-22 2008-05-13 Intel Corporation Nanostructure-based package interconnect
CN101331590B (en) * 2005-12-29 2011-04-20 纳米系统公司 Methods for oriented growth of nanowires on patterned substrates
US7741197B1 (en) 2005-12-29 2010-06-22 Nanosys, Inc. Systems and methods for harvesting and reducing contamination in nanowires
US20070155025A1 (en) * 2006-01-04 2007-07-05 Anping Zhang Nanowire structures and devices for use in large-area electronics and methods of making the same
US20080073743A1 (en) * 2006-02-17 2008-03-27 Lockheed Martin Corporation Templated growth of semiconductor nanostructures, related devices and methods
US7488661B2 (en) * 2006-03-07 2009-02-10 International Business Machines Corporation Device and method for improving interface adhesion in thin film structures
JP2007246600A (en) * 2006-03-14 2007-09-27 Shin Etsu Chem Co Ltd Self-organizing polymeric membrane material, self-organizing pattern, and method for forming pattern
DE102006021940A1 (en) * 2006-05-11 2007-11-22 Forschungszentrum Karlsruhe Gmbh Element, process for its preparation and its use
JP2009540333A (en) 2006-06-12 2009-11-19 プレジデント アンド フェロウズ オブ ハーバード カレッジ Nanosensors and related technologies
US7937153B2 (en) * 2006-06-19 2011-05-03 Second Sight Medical Products, Inc. Electrode with increased stability and method of manufacturing the same
US8142984B2 (en) * 2006-08-24 2012-03-27 The Regents Of The University Of California Lithographically patterned nanowire electrodeposition
WO2008033303A2 (en) 2006-09-11 2008-03-20 President And Fellows Of Harvard College Branched nanoscale wires
US7446014B2 (en) * 2006-10-12 2008-11-04 Sharp Laboratories Of America, Inc. Nanoelectrochemical cell
US7776760B2 (en) 2006-11-07 2010-08-17 Nanosys, Inc. Systems and methods for nanowire growth
JP5009993B2 (en) 2006-11-09 2012-08-29 ナノシス・インク. Nanowire arrangement method and deposition method
WO2008127314A1 (en) 2006-11-22 2008-10-23 President And Fellows Of Harvard College High-sensitivity nanoscale wire sensors
US8394483B2 (en) * 2007-01-24 2013-03-12 Micron Technology, Inc. Two-dimensional arrays of holes with sub-lithographic diameters formed by block copolymer self-assembly
DE102007010297A1 (en) * 2007-03-02 2008-09-04 Gesellschaft für Schwerionenforschung mbH Field emission source i.e. field emission cathode, for use in electron beam system, has nanowires provided on substrate, and field emission structure automatically transferring emission during failure of field emission structure
US8083953B2 (en) 2007-03-06 2011-12-27 Micron Technology, Inc. Registered structure formation via the application of directed thermal energy to diblock copolymer films
US8361337B2 (en) * 2007-03-19 2013-01-29 The University Of Massachusetts Method of producing nanopatterned templates
US8557128B2 (en) 2007-03-22 2013-10-15 Micron Technology, Inc. Sub-10 nm line features via rapid graphoepitaxial self-assembly of amphiphilic monolayers
US8294139B2 (en) 2007-06-21 2012-10-23 Micron Technology, Inc. Multilayer antireflection coatings, structures and devices including the same and methods of making the same
US7959975B2 (en) 2007-04-18 2011-06-14 Micron Technology, Inc. Methods of patterning a substrate
US8097175B2 (en) 2008-10-28 2012-01-17 Micron Technology, Inc. Method for selectively permeating a self-assembled block copolymer, method for forming metal oxide structures, method for forming a metal oxide pattern, and method for patterning a semiconductor structure
US8372295B2 (en) 2007-04-20 2013-02-12 Micron Technology, Inc. Extensions of self-assembled structures to increased dimensions via a “bootstrap” self-templating method
US10231344B2 (en) 2007-05-18 2019-03-12 Applied Nanotech Holdings, Inc. Metallic ink
US8404160B2 (en) 2007-05-18 2013-03-26 Applied Nanotech Holdings, Inc. Metallic ink
US8404124B2 (en) 2007-06-12 2013-03-26 Micron Technology, Inc. Alternating self-assembling morphologies of diblock copolymers controlled by variations in surfaces
US8080615B2 (en) 2007-06-19 2011-12-20 Micron Technology, Inc. Crosslinkable graft polymer non-preferentially wetted by polystyrene and polyethylene oxide
US8349546B2 (en) * 2007-06-28 2013-01-08 Ming-Nung Lin Fabricating method of nano-ring structure by nano-lithography
US7741721B2 (en) * 2007-07-31 2010-06-22 International Business Machines Corporation Electrical fuses and resistors having sublithographic dimensions
US8283258B2 (en) 2007-08-16 2012-10-09 Micron Technology, Inc. Selective wet etching of hafnium aluminum oxide films
CN101896814A (en) 2007-10-12 2010-11-24 Nxp股份有限公司 A sensor, a sensor array, and a method of operating a sensor
KR101355167B1 (en) * 2007-12-14 2014-01-28 삼성전자주식회사 Method of forming fine pattern using block copolymer having at least three polymer block
CN101465254B (en) * 2007-12-19 2010-12-08 北京富纳特创新科技有限公司 Thermal emission electron source and preparation method thereof
TWI383425B (en) * 2008-01-04 2013-01-21 Hon Hai Prec Ind Co Ltd Hot emission electron source and method of making the same
US8236386B2 (en) * 2008-01-24 2012-08-07 Wisys Technology Foundation Nanowire and microwire fabrication technique and product
US8999492B2 (en) 2008-02-05 2015-04-07 Micron Technology, Inc. Method to produce nanometer-sized features with directed assembly of block copolymers
US8101261B2 (en) 2008-02-13 2012-01-24 Micron Technology, Inc. One-dimensional arrays of block copolymer cylinders and applications thereof
TW200935635A (en) * 2008-02-15 2009-08-16 Univ Nat Chiao Tung Method of manufacturing nanometer-scale thermoelectric device
US8148188B2 (en) * 2008-02-26 2012-04-03 Imec Photoelectrochemical cell with carbon nanotube-functionalized semiconductor electrode
US7990068B2 (en) * 2008-03-04 2011-08-02 Xerox Corporation Field emission light emitting device
US8506849B2 (en) 2008-03-05 2013-08-13 Applied Nanotech Holdings, Inc. Additives and modifiers for solvent- and water-based metallic conductive inks
US8425982B2 (en) 2008-03-21 2013-04-23 Micron Technology, Inc. Methods of improving long range order in self-assembly of block copolymer films with ionic liquids
US8426313B2 (en) 2008-03-21 2013-04-23 Micron Technology, Inc. Thermal anneal of block copolymer films with top interface constrained to wet both blocks with equal preference
US8273591B2 (en) * 2008-03-25 2012-09-25 International Business Machines Corporation Super lattice/quantum well nanowires
US8114300B2 (en) * 2008-04-21 2012-02-14 Micron Technology, Inc. Multi-layer method for formation of registered arrays of cylindrical pores in polymer films
US8659852B2 (en) 2008-04-21 2014-02-25 Seagate Technology Llc Write-once magentic junction memory array
US8114301B2 (en) * 2008-05-02 2012-02-14 Micron Technology, Inc. Graphoepitaxial self-assembly of arrays of downward facing half-cylinders
US20090286383A1 (en) * 2008-05-15 2009-11-19 Applied Nanotech Holdings, Inc. Treatment of whiskers
US9730333B2 (en) 2008-05-15 2017-08-08 Applied Nanotech Holdings, Inc. Photo-curing process for metallic inks
US7852663B2 (en) * 2008-05-23 2010-12-14 Seagate Technology Llc Nonvolatile programmable logic gates and adders
US7855911B2 (en) * 2008-05-23 2010-12-21 Seagate Technology Llc Reconfigurable magnetic logic device using spin torque
EP2131406A1 (en) * 2008-06-02 2009-12-09 Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO A method for manufacturing a thermoelectric generator, a wearable thermoelectric generator and a garment comprising the same
US8007333B2 (en) * 2008-06-06 2011-08-30 Xerox Corporation Method of forming field emission light emitting device including the formation of an emitter within a nanochannel in a dielectric matrix
JP2009298911A (en) * 2008-06-12 2009-12-24 Canon Inc Block copolymer and method for processing substrate
US7881098B2 (en) 2008-08-26 2011-02-01 Seagate Technology Llc Memory with separate read and write paths
JP2010058314A (en) * 2008-09-02 2010-03-18 Fujifilm Corp Microphase separation structure on flexible substrate, and method of manufacturing the same
EP3279651B1 (en) 2008-09-02 2019-06-12 The Governing Council Of The University Of Toronto Methods using microelectrodes and biosensing devices incorporating the same
US7713753B2 (en) * 2008-09-04 2010-05-11 Seagate Technology Llc Dual-level self-assembled patterning method and apparatus fabricated using the method
US8211737B2 (en) * 2008-09-19 2012-07-03 The University Of Massachusetts Method of producing nanopatterned articles, and articles produced thereby
US8247033B2 (en) 2008-09-19 2012-08-21 The University Of Massachusetts Self-assembly of block copolymers on topographically patterned polymeric substrates
US8518837B2 (en) 2008-09-25 2013-08-27 The University Of Massachusetts Method of producing nanopatterned articles using surface-reconstructed block copolymer films
US7985994B2 (en) 2008-09-29 2011-07-26 Seagate Technology Llc Flux-closed STRAM with electronically reflective insulative spacer
US8389862B2 (en) 2008-10-07 2013-03-05 Mc10, Inc. Extremely stretchable electronics
US9289132B2 (en) 2008-10-07 2016-03-22 Mc10, Inc. Catheter balloon having stretchable integrated circuitry and sensor array
US8169810B2 (en) 2008-10-08 2012-05-01 Seagate Technology Llc Magnetic memory with asymmetric energy barrier
US8089132B2 (en) 2008-10-09 2012-01-03 Seagate Technology Llc Magnetic memory with phonon glass electron crystal material
US8039913B2 (en) * 2008-10-09 2011-10-18 Seagate Technology Llc Magnetic stack with laminated layer
US20100102405A1 (en) * 2008-10-27 2010-04-29 Seagate Technology Llc St-ram employing a spin filter
US8045366B2 (en) 2008-11-05 2011-10-25 Seagate Technology Llc STRAM with composite free magnetic element
US8043732B2 (en) 2008-11-11 2011-10-25 Seagate Technology Llc Memory cell with radial barrier
US7750386B2 (en) * 2008-11-12 2010-07-06 Seagate Technology Llc Memory cells including nanoporous layers containing conductive material
US7842938B2 (en) * 2008-11-12 2010-11-30 Seagate Technology Llc Programmable metallization cells and methods of forming the same
US7826181B2 (en) * 2008-11-12 2010-11-02 Seagate Technology Llc Magnetic memory with porous non-conductive current confinement layer
US8289756B2 (en) 2008-11-25 2012-10-16 Seagate Technology Llc Non volatile memory including stabilizing structures
US8441255B1 (en) * 2009-01-22 2013-05-14 Louisiana Tech University Research Foundation, a divison of Louisiana Tech University Foundation, Inc. Thermocooling of GMR sensors
US7826259B2 (en) 2009-01-29 2010-11-02 Seagate Technology Llc Staggered STRAM cell
US8216909B2 (en) 2009-03-11 2012-07-10 International Business Machines Corporation Field effect transistor with air gap dielectric
JP5740389B2 (en) 2009-03-27 2015-06-24 アプライド・ナノテック・ホールディングス・インコーポレーテッド Buffer layer to enhance photosintering and / or laser sintering
KR101101767B1 (en) * 2009-05-07 2012-01-05 한국과학기술원 methods for the preparation of coil-comb block copolymers and their nanostructures
US10490817B2 (en) 2009-05-19 2019-11-26 Oned Material Llc Nanostructured materials for battery applications
US20120135158A1 (en) 2009-05-26 2012-05-31 Sharp Kabushiki Kaisha Methods and systems for electric field deposition of nanowires and other devices
US8343585B2 (en) 2009-06-04 2013-01-01 Empire Technology Development Llc Self-assembling surface coating
US8834956B2 (en) * 2009-06-22 2014-09-16 Micron Technology, Inc. Methods of utilizing block copolymer to form patterns
US8623288B1 (en) 2009-06-29 2014-01-07 Nanosys, Inc. Apparatus and methods for high density nanowire growth
US7999338B2 (en) 2009-07-13 2011-08-16 Seagate Technology Llc Magnetic stack having reference layers with orthogonal magnetization orientation directions
EP2454615B1 (en) * 2009-07-14 2018-08-29 The University of Akron Electromagnetic processing line
US8422197B2 (en) 2009-07-15 2013-04-16 Applied Nanotech Holdings, Inc. Applying optical energy to nanoparticles to produce a specified nanostructure
US8428675B2 (en) * 2009-08-19 2013-04-23 Covidien Lp Nanofiber adhesives used in medical devices
WO2011038228A1 (en) 2009-09-24 2011-03-31 President And Fellows Of Harvard College Bent nanowires and related probing of species
DE102009043413B3 (en) * 2009-09-29 2011-06-01 Siemens Aktiengesellschaft Thermo-electric energy converter with three-dimensional microstructure, method for producing the energy converter and use of the energy converter
US8937293B2 (en) 2009-10-01 2015-01-20 Northeastern University Nanoscale interconnects fabricated by electrical field directed assembly of nanoelements
US20120318317A1 (en) * 2010-02-10 2012-12-20 Arizona Board Of Regents On Behalf Of The University Of Arizona Molecular thermoelectric device
JP2011171716A (en) * 2010-02-16 2011-09-01 Korea Electronics Telecommun Thermoelectric device, method of forming the same, and temperature sensing sensor and heat-source image sensor using the same
US8648324B2 (en) * 2010-03-19 2014-02-11 International Business Machines Corporation Glassy carbon nanostructures
KR101203136B1 (en) * 2010-03-22 2012-11-20 국립대학법인 울산과학기술대학교 산학협력단 Method for manufacturing nano-wire
WO2011135530A2 (en) 2010-04-28 2011-11-03 Kimberly-Clark Worldwide, Inc. Device for delivery of rheumatoid arthritis medication
MX343238B (en) 2010-04-28 2016-10-27 Kimberly-Clark Worldwide Incorporated Composite microneedle array including nanostructures thereon.
CA2797205C (en) 2010-04-28 2019-04-16 Kimberly-Clark Worldwide, Inc. Medical devices for delivery of sirna
AU2011311255B2 (en) 2010-04-28 2015-10-08 Sorrento Therapeutics, Inc. Method for increasing permeability of an epithelial barrier
KR101050198B1 (en) * 2010-07-26 2011-07-19 연세대학교 산학협력단 Method of generating nanowire diode
US8304493B2 (en) 2010-08-20 2012-11-06 Micron Technology, Inc. Methods of forming block copolymers
US10868077B2 (en) * 2010-10-18 2020-12-15 Wake Forest University Thermoelectric apparatus and applications thereof
KR20140009182A (en) 2010-10-22 2014-01-22 캘리포니아 인스티튜트 오브 테크놀로지 Nanomesh phononic structures for low thermal conductivity and thermoelectric energy conversion materials
WO2012064177A1 (en) * 2010-11-11 2012-05-18 Mimos Berhad Nanoporous membrane and method of forming thereof
US9422158B2 (en) * 2010-11-15 2016-08-23 The United States of Amerixa, as represented by the Secretary of the Navy Perforated contact electrode on vertical nanowire array
EP2663857B1 (en) 2011-01-11 2018-12-12 The Governing Council Of The University Of Toronto Protein detection method
ES2799422T3 (en) 2011-03-10 2020-12-17 General Atomics Diagnostic and sample preparation methods and devices
US9205420B2 (en) * 2011-04-22 2015-12-08 President And Fellows Of Harvard College Nanostructures, systems, and methods for photocatalysis
US9156682B2 (en) 2011-05-25 2015-10-13 The University Of Massachusetts Method of forming oriented block copolymer line patterns, block copolymer line patterns formed thereby, and their use to form patterned articles
KR102000302B1 (en) 2011-05-27 2019-07-15 엠씨10, 인크 Electronic, optical and/or mechanical apparatus and systems and methods for fabricating same
US20130019918A1 (en) 2011-07-18 2013-01-24 The Regents Of The University Of Michigan Thermoelectric devices, systems and methods
US20140242744A1 (en) * 2011-09-26 2014-08-28 Solarity, Inc. Substrate and superstrate design and process for nano-imprinting lithography of light and carrier collection management devices
US11110066B2 (en) 2011-10-27 2021-09-07 Sorrento Therapeutics, Inc. Implantable devices for delivery of bioactive agents
US8900963B2 (en) 2011-11-02 2014-12-02 Micron Technology, Inc. Methods of forming semiconductor device structures, and related structures
US10205080B2 (en) 2012-01-17 2019-02-12 Matrix Industries, Inc. Systems and methods for forming thermoelectric devices
US20130200498A1 (en) * 2012-02-03 2013-08-08 Applied Materials, Inc. Methods and apparatus for lithography using a resist array
JP6082726B2 (en) * 2012-02-24 2017-02-15 国立大学法人九州工業大学 Thermoelectric conversion material
JP5981732B2 (en) * 2012-03-02 2016-08-31 国立大学法人九州大学 Thermoelectric conversion material using substrate having nanostructure and manufacturing method thereof
WO2013149205A1 (en) 2012-03-29 2013-10-03 California Institute Of Technology Phononic structures and related devices and methods
US9784802B1 (en) * 2012-04-11 2017-10-10 Louisiana Tech Research Corporation GMR nanowire sensors
US10718636B1 (en) * 2012-04-11 2020-07-21 Louisiana Tech Research Corporation Magneto-resistive sensors
US9598776B2 (en) 2012-07-09 2017-03-21 Pen Inc. Photosintering of micron-sized copper particles
CN104620352B (en) * 2012-07-10 2017-05-10 株式会社尼康 Mark formation method and device manufacturing method
JP2014033051A (en) * 2012-08-02 2014-02-20 Toshiba Corp Method for forming pattern and method for manufacturing semiconductor device
JP6353447B2 (en) 2012-08-17 2018-07-04 マトリックス インダストリーズ,インコーポレイテッド System and method for forming a thermoelectric device
US9153477B2 (en) * 2012-09-28 2015-10-06 Intel Corporation Directed self assembly of block copolymers to form vias aligned with interconnects
US9087699B2 (en) 2012-10-05 2015-07-21 Micron Technology, Inc. Methods of forming an array of openings in a substrate, and related methods of forming a semiconductor device structure
US9171794B2 (en) 2012-10-09 2015-10-27 Mc10, Inc. Embedding thin chips in polymer
WO2014070795A1 (en) 2012-10-31 2014-05-08 Silicium Energy, Inc. Methods for forming thermoelectric elements
US8956808B2 (en) 2012-12-04 2015-02-17 Globalfoundries Inc. Asymmetric templates for forming non-periodic patterns using directed self-assembly materials
FR3000235B1 (en) 2012-12-21 2016-06-24 Arkema France PROCESS FOR MANUFACTURING NANOLITHOGRAPHIC MASKS
US9123421B2 (en) 2013-01-21 2015-09-01 International Business Machines Corporation Racetrack memory cells with a vertical nanowire storage element
US8790522B1 (en) 2013-02-11 2014-07-29 Globalfoundries Inc. Chemical and physical templates for forming patterns using directed self-assembly materials
JP5998078B2 (en) * 2013-02-27 2016-09-28 リンテック株式会社 Thermoelectric conversion material, manufacturing method thereof, and thermoelectric conversion module
EP2973764B1 (en) 2013-03-14 2017-03-01 Wake Forest University Thermoelectric apparatus
US9229328B2 (en) 2013-05-02 2016-01-05 Micron Technology, Inc. Methods of forming semiconductor device structures, and related semiconductor device structures
US20140377965A1 (en) * 2013-06-19 2014-12-25 Globalfoundries Inc. Directed self-assembly (dsa) formulations used to form dsa-based lithography films
US9281203B2 (en) * 2013-08-23 2016-03-08 Taiwan Semiconductor Manufacturing Co., Ltd. Silicon dot formation by direct self-assembly method for flash memory
US9064821B2 (en) 2013-08-23 2015-06-23 Taiwan Semiconductor Manufacturing Co. Ltd. Silicon dot formation by self-assembly method and selective silicon growth for flash memory
US10014184B2 (en) 2013-09-05 2018-07-03 Applied Materials, Inc. Methods and apparatus for forming a resist array using chemical mechanical planarization
US9177795B2 (en) 2013-09-27 2015-11-03 Micron Technology, Inc. Methods of forming nanostructures including metal oxides
US20150160072A1 (en) * 2013-12-06 2015-06-11 Rensselaer Polytechnic Institute Oriented backscattering wide dynamic-range optical radiation sensor
US9466527B2 (en) 2014-02-23 2016-10-11 Tokyo Electron Limited Method for creating contacts in semiconductor substrates
JP6220292B2 (en) * 2014-03-11 2017-10-25 株式会社東芝 Magnetic memory, reproducing method of magnetic memory, and recording method of magnetic memory
JP6611727B2 (en) 2014-03-25 2019-11-27 マトリックス インダストリーズ,インコーポレイテッド Thermoelectric device and system
US10739673B2 (en) 2014-06-20 2020-08-11 Taiwan Semiconductor Manufacturing Company Limited Preparing patterned neutral layers and structures prepared using the same
US9715965B2 (en) * 2014-09-17 2017-07-25 Arm Limited Electrical component with random electrical characteristic
EP3213098B1 (en) * 2014-10-31 2019-02-27 King Abdullah University Of Science And Technology Magnetic nanocomposite sensor
KR20160066650A (en) * 2014-12-02 2016-06-13 삼성디스플레이 주식회사 Fabrication method of display device and display device
EP3314245A4 (en) 2015-06-25 2019-02-27 Roswell Biotechnologies, Inc Biomolecular sensors and methods
WO2017132586A1 (en) 2016-01-28 2017-08-03 Roswell Biotechnologies, Inc. Methods and apparatus for measuring analytes using large scale molecular electronics sensor arrays
US10712334B2 (en) 2016-01-28 2020-07-14 Roswell Biotechnologies, Inc. Massively parallel DNA sequencing apparatus
US10737263B2 (en) 2016-02-09 2020-08-11 Roswell Biotechnologies, Inc. Electronic label-free DNA and genome sequencing
US10597767B2 (en) 2016-02-22 2020-03-24 Roswell Biotechnologies, Inc. Nanoparticle fabrication
US20170256696A1 (en) * 2016-03-01 2017-09-07 Taiwan Semiconductor Manufacturing Co., Ltd. Thermoelectric generator
TW201809931A (en) 2016-05-03 2018-03-16 麥崔克斯工業股份有限公司 Thermoelectric devices and systems
US10304803B2 (en) * 2016-05-05 2019-05-28 Invensas Corporation Nanoscale interconnect array for stacked dies
US10336017B2 (en) * 2016-06-30 2019-07-02 Boeing Company, The Microwire array devices and methods for fabricating polymeric sheets containing microwires
US9829456B1 (en) 2016-07-26 2017-11-28 Roswell Biotechnologies, Inc. Method of making a multi-electrode structure usable in molecular sensing devices
USD819627S1 (en) 2016-11-11 2018-06-05 Matrix Industries, Inc. Thermoelectric smartwatch
EP3568407A4 (en) 2017-01-10 2020-12-23 Roswell Biotechnologies, Inc Methods and systems for dna data storage
EP3571286A4 (en) 2017-01-19 2020-10-28 Roswell Biotechnologies, Inc Solid state sequencing devices comprising two dimensional layer materials
US10243156B2 (en) 2017-03-16 2019-03-26 International Business Machines Corporation Placement of carbon nanotube guided by DSA patterning
EP3615685A4 (en) 2017-04-25 2021-01-20 Roswell Biotechnologies, Inc Enzymatic circuits for molecular sensors
US10508296B2 (en) 2017-04-25 2019-12-17 Roswell Biotechnologies, Inc. Enzymatic circuits for molecular sensors
EP3619161A4 (en) * 2017-05-01 2021-01-20 Monash University Standing nanowire-based elastic conductors
EP3622086A4 (en) 2017-05-09 2021-04-21 Roswell Biotechnologies, Inc Binding probe circuits for molecular sensors
KR20200039795A (en) 2017-08-30 2020-04-16 로스웰 바이오테크놀로지스 인코포레이티드 Progressive enzyme molecular electronic sensors for DNA data storage
KR20200067871A (en) 2017-10-10 2020-06-12 로스웰 바이오테크놀로지스 인코포레이티드 Methods, devices and systems for storing amplified DNA data
US10957853B2 (en) 2018-09-18 2021-03-23 International Business Machines Corporation Modifying material parameters of a nanoscale device post-fabrication
US11695100B2 (en) 2020-01-21 2023-07-04 Nanosys, Inc. Light emitting diode containing a grating and methods of making the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5306661A (en) * 1992-06-12 1994-04-26 The United States Of America As Represented By The Secretary Of The Navy Method of making a semiconductor device using a nanochannel glass matrix
US6187165B1 (en) * 1997-10-02 2001-02-13 The John Hopkins University Arrays of semi-metallic bismuth nanowires and fabrication techniques therefor
US6388185B1 (en) * 1998-08-07 2002-05-14 California Institute Of Technology Microfabricated thermoelectric power-generation devices

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4789648A (en) 1985-10-28 1988-12-06 International Business Machines Corporation Method for producing coplanar multi-level metal/insulator films on a substrate and for forming patterned conductive lines simultaneously with stud vias
KR100365444B1 (en) * 1996-09-18 2004-01-24 가부시끼가이샤 도시바 Vacuum micro device and image display device using the same
JPH10106960A (en) * 1996-09-25 1998-04-24 Sony Corp Manufacture of quantum thin line
US5948470A (en) 1997-04-28 1999-09-07 Harrison; Christopher Method of nanoscale patterning and products made thereby
US6187164B1 (en) 1997-09-30 2001-02-13 Symyx Technologies, Inc. Method for creating and testing a combinatorial array employing individually addressable electrodes
JP4146978B2 (en) * 1999-01-06 2008-09-10 キヤノン株式会社 Manufacturing method of structure having pores, and structure manufactured by the manufacturing method
US6185961B1 (en) 1999-01-27 2001-02-13 The United States Of America As Represented By The Secretary Of The Navy Nanopost arrays and process for making same
US6105381A (en) * 1999-03-31 2000-08-22 International Business Machines Corporation Method and apparatus for cooling GMR heads for magnetic hard disks
US6504292B1 (en) * 1999-07-15 2003-01-07 Agere Systems Inc. Field emitting device comprising metallized nanostructures and method for making the same
US6538367B1 (en) * 1999-07-15 2003-03-25 Agere Systems Inc. Field emitting device comprising field-concentrating nanoconductor assembly and method for making the same
US6286226B1 (en) * 1999-09-24 2001-09-11 Agere Systems Guardian Corp. Tactile sensor comprising nanowires and method for making the same
US6426590B1 (en) * 2000-01-13 2002-07-30 Industrial Technology Research Institute Planar color lamp with nanotube emitters and method for fabricating
US7375366B2 (en) * 2000-02-25 2008-05-20 Sharp Kabushiki Kaisha Carbon nanotube and method for producing the same, electron source and method for producing the same, and display
WO2001070873A2 (en) * 2000-03-22 2001-09-27 University Of Massachusetts Nanocylinder arrays
JP2002141633A (en) * 2000-10-25 2002-05-17 Lucent Technol Inc Article comprising vertically nano-interconnected circuit device and method for making the same
KR100362377B1 (en) * 2000-12-05 2002-11-23 한국전자통신연구원 Field emission devices using carbon nanotubes and method thereof
MXPA03008935A (en) * 2001-03-30 2004-06-30 Univ California Methods of fabricating nanostructures and nanowires and devices fabricated therefrom.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5306661A (en) * 1992-06-12 1994-04-26 The United States Of America As Represented By The Secretary Of The Navy Method of making a semiconductor device using a nanochannel glass matrix
US6187165B1 (en) * 1997-10-02 2001-02-13 The John Hopkins University Arrays of semi-metallic bismuth nanowires and fabrication techniques therefor
US6388185B1 (en) * 1998-08-07 2002-05-14 California Institute Of Technology Microfabricated thermoelectric power-generation devices

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
FAN ET AL.: 'Self-oriented regular arrays of carbon nanotubes and their field emission properties' SCIENCE vol. 283, 22 January 1999, pages 512 - 514, XP000930011 *
MANSKY ET AL.: 'Monolayer films of diblock copolymer microdomains for nanolithographic applications' JOURNAL OF MATERIALS vol. 30, 1995, pages 1987 - 1992, XP002953658 *
See also references of EP1374310A2 *

Cited By (53)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004056699A3 (en) * 2002-12-20 2005-11-24 Leibniz Inst Polymerforschung Nanoparticles, nanoscopic structures and method for production thereof
WO2004056699A2 (en) * 2002-12-20 2004-07-08 Leibniz-Institut Für Polymerforschung Dresden E.V. Nanoparticles, nanoscopic structures and method for production thereof
KR100845565B1 (en) * 2003-12-01 2008-07-10 더 보드 오브 트러스티즈 오브 더 유니버시티 오브 일리노이 Methods and devices for fabricating three-dimensional nanoscale structures
WO2005054119A3 (en) * 2003-12-01 2005-10-13 Univ Illinois Methods and devices for fabricating three-dimensional nanoscale structures
US7704684B2 (en) 2003-12-01 2010-04-27 The Board Of Trustees Of The University Of Illinois Methods and devices for fabricating three-dimensional nanoscale structures
US11088268B2 (en) 2004-06-04 2021-08-10 The Board Of Trustees Of The University Of Illinois Methods and devices for fabricating and assembling printable semiconductor elements
US9761444B2 (en) 2004-06-04 2017-09-12 The Board Of Trustees Of The University Of Illinois Methods and devices for fabricating and assembling printable semiconductor elements
US10374072B2 (en) 2004-06-04 2019-08-06 The Board Of Trustees Of The University Of Illinois Methods and devices for fabricating and assembling printable semiconductor elements
US9768086B2 (en) 2004-06-04 2017-09-19 The Board Of Trustees Of The University Of Illinois Methods and devices for fabricating and assembling printable semiconductor elements
US8558311B2 (en) 2004-09-16 2013-10-15 Nanosys, Inc. Dielectrics using substantially longitudinally oriented insulated conductive wires
US8039726B2 (en) 2005-05-26 2011-10-18 General Electric Company Thermal transfer and power generation devices and methods of making the same
WO2007133894A3 (en) * 2006-05-12 2008-09-25 Gen Electric Low dimensional thermoelectrics fabricated by semiconductor wafer etching
WO2007133894A2 (en) * 2006-05-12 2007-11-22 General Electric Company Low dimensional thermoelectrics fabricated by semiconductor wafer etching
WO2008054854A3 (en) * 2006-05-31 2008-10-09 Gen Electric Thermoelectric nanotube arrays
WO2008054854A2 (en) * 2006-05-31 2008-05-08 General Electric Company Thermoelectric nanotube arrays
WO2008060282A1 (en) * 2006-11-17 2008-05-22 General Electric Company Thermal transfer and power generation devices and methods of making the same
US8101449B2 (en) 2007-01-03 2012-01-24 Toyota Motor Engineering & Manufacturing North America, Inc. Process for altering thermoelectric properties of a material
US7781317B2 (en) 2007-01-03 2010-08-24 Toyota Motor Engineering & Manufacturing North America, Inc. Method of non-catalytic formation and growth of nanowires
JP2008189543A (en) * 2007-01-03 2008-08-21 Toyota Motor Engineering & Manufacturing North America Inc Method of non-catalytic formation and growth of nanowires
TWI469183B (en) * 2007-02-08 2015-01-11 Micron Technology Inc Methods using block copolymer self-assembly for sub-lithographic patterning
US8974678B2 (en) 2007-02-08 2015-03-10 Micron Technology, Inc. Methods using block co-polymer self-assembly for sub-lithographic patterning
US9629586B2 (en) 2008-10-07 2017-04-25 Mc10, Inc. Systems, methods, and devices using stretchable or flexible electronics for medical applications
US9647171B2 (en) 2009-05-12 2017-05-09 The Board Of Trustees Of The University Of Illinois Printed assemblies of ultrathin, microscale inorganic light emitting diodes for deformable and semitransparent displays
US10546841B2 (en) 2009-05-12 2020-01-28 The Board Of Trustees Of The University Of Illinois Printed assemblies of ultrathin, microscale inorganic light emitting diodes for deformable and semitransparent displays
US8354459B2 (en) 2009-08-18 2013-01-15 Japan Science And Technology Agency Method for producing polymer material
US9723122B2 (en) 2009-10-01 2017-08-01 Mc10, Inc. Protective cases with integrated electronics
US9936574B2 (en) 2009-12-16 2018-04-03 The Board Of Trustees Of The University Of Illinois Waterproof stretchable optoelectronics
US10441185B2 (en) 2009-12-16 2019-10-15 The Board Of Trustees Of The University Of Illinois Flexible and stretchable electronic systems for epidermal electronics
US11057991B2 (en) 2009-12-16 2021-07-06 The Board Of Trustees Of The University Of Illinois Waterproof stretchable optoelectronics
US10918298B2 (en) 2009-12-16 2021-02-16 The Board Of Trustees Of The University Of Illinois High-speed, high-resolution electrophysiology in-vivo using conformal electronics
WO2011074852A1 (en) * 2009-12-18 2011-06-23 Korea University Research And Business Foundation Use of block copolymers for preparing conductive nanostructures
US8202436B2 (en) 2009-12-18 2012-06-19 Korea University Research And Business Foundation Use of block copolymers for preparing conductive nanostructures
US9986924B2 (en) 2010-03-17 2018-06-05 The Board Of Trustees Of The University Of Illinois Implantable biomedical devices on bioresorbable substrates
US9765934B2 (en) 2011-05-16 2017-09-19 The Board Of Trustees Of The University Of Illinois Thermally managed LED arrays assembled by printing
US10349860B2 (en) 2011-06-03 2019-07-16 The Board Of Trustees Of The University Of Illinois Conformable actively multiplexed high-density surface electrode array for brain interfacing
US9691873B2 (en) 2011-12-01 2017-06-27 The Board Of Trustees Of The University Of Illinois Transient devices designed to undergo programmable transformations
US10396173B2 (en) 2011-12-01 2019-08-27 The Board Of Trustees Of The University Of Illinois Transient devices designed to undergo programmable transformations
US10052066B2 (en) 2012-03-30 2018-08-21 The Board Of Trustees Of The University Of Illinois Appendage mountable electronic devices conformable to surfaces
US10357201B2 (en) 2012-03-30 2019-07-23 The Board Of Trustees Of The University Of Illinois Appendage mountable electronic devices conformable to surfaces
US10350794B2 (en) 2013-10-31 2019-07-16 University Of Florida Research Foundation, Inc. Porous polymer membranes, methods of making, and methods of use
US10730208B2 (en) 2013-10-31 2020-08-04 University Of Florida Research Foundation, Inc. Porous polymer membranes, methods of making, and methods of use
US10717108B2 (en) 2014-10-17 2020-07-21 University Of Florida Research Foundation, Inc. Methods and structures for light regulating coatings
US10808095B2 (en) 2015-05-08 2020-10-20 University Of Florida Research Foundation, Inc. Macroporous photonic crystal membrane, methods of making, and methods of use
US11029198B2 (en) 2015-06-01 2021-06-08 The Board Of Trustees Of The University Of Illinois Alternative approach for UV sensing
US11118965B2 (en) 2015-06-01 2021-09-14 The Board Of Trustees Of The University Of Illinois Miniaturized electronic systems with wireless power and near-field communication capabilities
US10925543B2 (en) 2015-11-11 2021-02-23 The Board Of Trustees Of The University Of Illinois Bioresorbable silicon electronics for transient implants
US11795281B2 (en) 2016-08-15 2023-10-24 University Of Florida Research Foundation, Inc. Methods and compositions relating to tunable nanoporous coatings
US11467094B2 (en) 2017-05-17 2022-10-11 University Of Florida Research Foundation, Inc. Methods and sensors for detection
US11781993B2 (en) 2017-05-17 2023-10-10 University Of Florida Research Foundation, Inc. Methods and sensors for detection
US11480527B2 (en) 2017-12-20 2022-10-25 University Of Florida Research Foundation, Inc. Methods and sensors for detection
US11705527B2 (en) 2017-12-21 2023-07-18 University Of Florida Research Foundation, Inc. Substrates having a broadband antireflection layer and methods of forming a broadband antireflection layer
US11819277B2 (en) 2018-06-20 2023-11-21 University Of Florida Research Foundation, Inc. Intraocular pressure sensing material, devices, and uses thereof
RU199472U1 (en) * 2020-06-25 2020-09-02 Федеральное государственное автономное образовательное учреждение высшего образования "Национальный исследовательский университет ИТМО" PHOTOSENSOR BASED ON A FLEXIBLE MEMBRANE WITH FILAMENT NANOCRYSTALS

Also Published As

Publication number Publication date
US7189435B2 (en) 2007-03-13
EP1374310A4 (en) 2008-02-20
EP1374310A2 (en) 2004-01-02
US20070200477A1 (en) 2007-08-30
WO2002073699A3 (en) 2002-11-14
US20020158342A1 (en) 2002-10-31
CA2451882A1 (en) 2002-09-19
KR20030087642A (en) 2003-11-14
WO2002073699A9 (en) 2004-05-06
JP2004527905A (en) 2004-09-09
KR100878281B1 (en) 2009-01-12

Similar Documents

Publication Publication Date Title
US7189435B2 (en) Nanofabrication
US7190049B2 (en) Nanocylinder arrays
KR100272702B1 (en) Tunnelling device and method of producing a tunnelling device
Sun et al. Tuning the properties of magnetic nanowires
JP3859199B2 (en) Carbon nanotube horizontal growth method and field effect transistor using the same
Bal et al. Nanofabrication of integrated magnetoelectronic devices using patterned self-assembled copolymer templates
Spohr Status of ion track technology—Prospects of single tracks
US20100258443A1 (en) Methods of fabricating nanowires and electrodes having nanogaps
US6562633B2 (en) Assembling arrays of small particles using an atomic force microscope to define ferroelectric domains
Kagan et al. Self-assembly for electronics
WO2001004970A1 (en) Ferromagnetic double quantum well tunnel magneto-resistance device
AU2002255741A1 (en) Nanofabrication
EP0911892A2 (en) Magneto-resistance effect device and method of manufacturing the same
Singh et al. Superconductivity in nanoscale systems
Chen et al. Electrochemical Fabrication of Metal Nanocontacts and Nanogaps
Petrov et al. Creation of nanoscale electronic devices by the swift heavy ion technology
Chen et al. Nanocontacts and Nanogaps
Schelhas Using Solution Phase Self-Assembly to Control the Properties of Magnetic and Magnetoelectric Nanostructures
Masuda Combined Transmission Electron Microscopy—In situ Measurements of Physical and Mechanical Properties of Nanometer-sized Single-phase Metallic structucre
Felter et al. Formation ofWell-defined Nanocolumns by Ion Tracking Lithography
Bandyopadhyay et al. Self-assembled neuromorphic networks
Tyagi et al. Scope of Magnetic Tunnel Junction Based Molecular Electronics and Spintronics Devices
Fodor Study of magnetic nanostructures in hexagonally ordered porous alumina
Tran Self-assembly and electronic transport properties of nanoparticle arrays
Tuominen et al. Nanofabrication

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
AK Designated states

Kind code of ref document: A3

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A3

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
WWE Wipo information: entry into national phase

Ref document number: 2451882

Country of ref document: CA

Ref document number: 1020037012051

Country of ref document: KR

WWE Wipo information: entry into national phase

Ref document number: 2002572644

Country of ref document: JP

Ref document number: 2002255741

Country of ref document: AU

WWE Wipo information: entry into national phase

Ref document number: 2002725158

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2002725158

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

COP Corrected version of pamphlet

Free format text: PAGES 1/21-21/21, DRAWINGS, REPLACED BY NEW PAGES 1/20-20/20; DUE TO LATE TRANSMITTAL BY THE RECEIVING OFFICE