CA1290080C - Method and apparatus for plasma source ion implantation - Google Patents
Method and apparatus for plasma source ion implantationInfo
- Publication number
- CA1290080C CA1290080C CA000556845A CA556845A CA1290080C CA 1290080 C CA1290080 C CA 1290080C CA 000556845 A CA000556845 A CA 000556845A CA 556845 A CA556845 A CA 556845A CA 1290080 C CA1290080 C CA 1290080C
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- Canada
- Prior art keywords
- chamber
- target object
- plasma
- ions
- target
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32412—Plasma immersion ion implantation
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/48—Ion implantation
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B31/00—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor
- C30B31/20—Doping by irradiation with electromagnetic waves or by particle radiation
- C30B31/22—Doping by irradiation with electromagnetic waves or by particle radiation by ion-implantation
Abstract
METHOD AND APPARATUS FOR PLASMA SOURCE ION IMPLANTATION
ABSTRACT OF THE DISCLOSURE
Ion implantation into surfaces of three-dimensional targets is achieved by forming an ionized plasma about the target within an enclosing chamber and applying a pulse of high voltage between the target and the conductive walls of the chamber. Ions from the plasma are driven into the target object surfaces from all sides simultaneously without the need for manipulation of the target object.
Repetitive pulses of high voltage, typically 20 kilovolts or higher, causes the ions to be driven deeply into the target. The plasma may be formed of a neutral gas introduced into the evacuated chamber and ionized therein with ionizing radiation so that a constant source of plasma is provided which surrounds the target object during the implantation process. Significant increases in the surface hardness and wear characteristics of various materials are obtained with ion implantation in this manner.
ABSTRACT OF THE DISCLOSURE
Ion implantation into surfaces of three-dimensional targets is achieved by forming an ionized plasma about the target within an enclosing chamber and applying a pulse of high voltage between the target and the conductive walls of the chamber. Ions from the plasma are driven into the target object surfaces from all sides simultaneously without the need for manipulation of the target object.
Repetitive pulses of high voltage, typically 20 kilovolts or higher, causes the ions to be driven deeply into the target. The plasma may be formed of a neutral gas introduced into the evacuated chamber and ionized therein with ionizing radiation so that a constant source of plasma is provided which surrounds the target object during the implantation process. Significant increases in the surface hardness and wear characteristics of various materials are obtained with ion implantation in this manner.
Description
~2~ 30 METHOD A~D APPARATUS FOR PLASMA SOURCE ION IMPLANTATIO~J
FIELD OF THE INVENTION
This invention pertains qenerally to the field of surface treatment and paxticularly to surface treatment by 5 ion implantation techniques.
BACKGROUND OF THE INVENTION
Ion implantation offers great commercial promi-se for the improvement of the surface characteristics of a variety o~ materials, including metals, ceramics and 10 plastics. In the conventional ion implantation process, ions are formed into a beam and accelerated to high energy before being directed into the surace of a solid target.
Because the ion implantation process is not limited by the thermodyn~mic constraints of more conventional techniques, 15 ion implantation allows new materials to be produced with new surface properties. In particular, implantation can be used to improve greatly the friction, wear and corrosion resistance properties of the surfaces of metals. For example, implantation of nitrogen ions in a 20 titanium alloy artificial hip joint has increased the joint lifetime by a factor of 400 or more. The properties of ceramic components and ceramic cutting tools can also be improved by ion implantation. For a general discussion of the techniques and potential advantages of ion implantation, see generally S. Picraux, et al., "Ion Implantation of Surfaces", Scientific American, Vol. 252, No. 3, pp. 102-113, 1985; D.M. Hulett, et al., "lon 5 Nitriding and Ion Implantation: A Comparison," Metal Progress, August 1985, pp. 18-21; V.M. Cassidy, "Ion Implantation Process rroughens Metalworking Tools," Modern ~letals, Septe~ber 1984, pp. 65-67.
While commercially viable applications of conventional 10 ion implantation techniques have been demonstrated, the relatively high cost of the process has limited its use thus far to high unit cost items having very special applications. A significant factor in the substantial production costs of conventional ion implantation is that 15 significant and time-consuming manipulation of the ion beam and the target is required to obtain implantation over the entire surface of a three-dimensional target. In conventional ion implantation, the ions are extracted from a plasma source and focused into a beam which is 20 accelerated to the desired energy and then rastered across one face of the target to uniformly implant the surface of that face. Because of the line of sight nature of this ion implantation techni~ue, a manipulator platform or stage is required which can support the target for 25 rotation in the beam so that all sides of the target can be implanted. The need to manipulate a three-dimensional target to allow all sides of the target to be implanted adds cost and complexity, constrains the maximum size of the target which can be-implanted, and increases the total 30 time required to obtain satisfactory implantation of all target surfaces for relatively large targets. Because the ions travel to the target in a largely unidirectional beam, it is often necessary to mask targets having convex surfaces so that ions are allowed to strike the target 35 only at angles substantially normal to the target surface. Normal incidence of ions to the surface is preferred since as the difference in the angle of 8~
incidence from the normal increases, sputtering increases and the net retained dose in the target decreases.
The present disclosure is directed to significantly improved 5 production efficiencies in ion implantation o three-dimensional materials by achieving implantation from all sides of ~he target simultaneously. Consequently, the production eficiensy for implantation of three~dimensional objects is greatly increased over conventional ion implantation techniques. Since the target need not be manipulated, complicated target manipulation apparatus is not required.
In plasma source ion implantation here described, the target to be implanted is ~urrounded by the plasma source within an evacuated chamber. A high negative potential pulse is then applied to the target relative to the walls o~ the chamber to accelerate iOllS from the plasma across the plasma sheath toward the target in directions s~bstantially normal to the sur~aces of the target at the points where the ions impinge upon the surface. The high voltage pulse, e.y., typically 20 kilovolts (kV) or higher, causes the.ions to be driven deeply into the target object, typically causing ions to be distributed into the cry~tal lattice of the target to form a modified material layer over all exposed sur~aces of the taxget object. Multiple pulses may be applisd between the taxget and the chamber walls in rapid succession to perform multiple implantation until a desired concentration of implanted ions within the target object is achieved.
Preferably, the ion source plasma surrounding the target object is formed by introducing the ion source material in a gas or vapor orm into the highly evacuated space within the confining chamber. The gaseous material may then be ionized by directing ionizing radiation, such as a difuse beam of electrons, through the source gas in a conventional manner. Consequently, a plasma of ions is formed which completely surrounds the target object itself so that ions may b~ implanted into the target from all sides, if desired.
Multiple targets, properly spaced within the plasma, may be implanted simultaneously in accordance with the invention.
Utilizing the new ion implantation process and apparatus, ion implantations may be performed on complex, three-dimensional objects formed of a great variety of materials, including pure metals, alloys, semi-conductors, ceramics, and organic polymers. signi~icant increases in surface hardness are obtained with ion implantation o~ a variety o~ source materials, including gases such as nitrogen, into metal and ceramic surfaces. Ion implantation of organic plastic materials can produce desirable surface characteristic modifications including a change in the optical properties and the electrical conductivity of the polymer. Ion implantation is also found to be particularly beneficial when used in con~unction with conventional heat treatment hardening techniques. Metal objects which have been both ion implanted in accordance with the new process and apparatus and heat treated are found to exhibit significantly greater hardness and resistance to wear than objects which are only heat treated or ion implanted, but not both.
More particularly, in accordance with a first aspect of the invention there is provided a method of implanting ions from a plasma into a target object comprising the steps of:
~ a) positioning the target object in an enclosing chamber;
(b~ generating a plasma of ions which surrounds the target object;
(c~ then, independently from generating the plasma, applying a high negative voltage pulse to the target object to accelerate the ions in the plasma toward the target from the plasma surrounding the target at an ion enPrgy sufficient to implant ions impacting the target object beneath the surface of and into the crystal lattice of the target objsct.
3L~9V08~
- 4a -In accordance with a second aspect of the invention there is provided a method of implanting ions in a target object comprising the st~ps of:
(a) providing an enclosing chamber having walls of electrically conductive material:
(b) suspending a target object within the chamber ~paced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) i~dependently of forming the plasma, applying a pulse o~ high voltage between the chamber walls and the target object at a voltage suffizient to implant ions from the plasma into the target object.
In accordance with a third asp~ct of the invention there is provided a method of implanting ions in a target object comprising the steps of:
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a target object within the chamber spaced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) applying repetitive pulses of high voltage between the chamber walls and the target object independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target object, the width of the pulsPs being ~elected such that the plasma sheath surrounding the target object does not expand to contact the enclosure walls during the pulse.
In accordance with a fourth aspect of the invention there is provided a method of implanting ions in a target object csmprising the steps of:
(a) providing an enclosing chamber having walls of electrically conductive material;
, , 12~013~
- 4b -(b) suspending a plurality of target objects within the chamber spaced away from the walls of the chamber and from each other;
(c) evacuating the interior of the chamber to a ve~y low base pressure;
(d) forming a plasma of ions in the chamber around the target objects;
(e) applying repetitive pulses of high voltage between the chamber walls and the target objects independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target objects, the width of each pulse of high voltage selected such that the plasma sheath surrounding each target object does not expand during the pulse to contact the plasma sheath surrounding another target object or to contact the walls of the chamber.
In accordance with a fifth aspect of the invention there is provided an apparatus for implanting ions in a target object comprising:
(a) electrically conductive enclosure walls defining an enclosing chamber surrounding a sealed space;
(b) means for supporting a target object within the enclosing chamber at a position spaced away from and electrically isolated from the enclosure walls of the chamber and for providing an electrical connection between the target object so supported and the exterior of the chamber;
(c) means for forming a plasma of ions of a selected material within the enclosing chamber around the target object;
(d) means for evacuating the interior of the enclosing chamber to a desired low pressure level; and (e) means, independent of the means for forming a plasma, for applying a pulse of voltage between the enclosure walls and the target object sufficient to implant ions from the plasma into the target object.
Embodiments of the invention will now be described with reference to the accompanying drawings in which:
Fig. 1 is a simplified cross-sectional view through an ion implantation chamber with associated apparatus embodying the present invention.
Fig. 2 is a cross-section through the ion implantation chamber of Fig. 1 taken generally along the lines 2-2 of Fig. 1.
900~30 Fig 3 is a graph showing Auger measurements of nitrogen ion concen~ration versus depth for a silicon target implanted with 25 keV nitrogen ions.
Fig. 4 is a graph showing Knoop hardness or a 5160 5 steel target for a sample as received, with ion implantation alone, with heat treatment alone, and with heat treatment and ion implantation.
~ ig. 5 i8 a simpli~ied perspective view o~ several identical cylindrical targets mounted within the ion lO implantation chamber to be implanted simultaneously.
Fig. 6 i a schematic view iLlustrating the spacing requirements ~or multiple cylindrical targets in the ion implantation chamber.
Fig. 7 are graphs showing calculated spacing 15 requirements for planar, cylindrical and spherical targets under various implantation conditions.
DESCRIPTIOM OF THE PREFERRED EMBODIMENTS
With reference to the drawings, an ion implantation apparatus is shown generally at lO in partial cross-section in Fig. l.
The apparatus 10 includes an enclosing chamber ll having conductive walls, e.g., of stainless steel or aluminum, which may be ~ormed, as shown, with an outer cylindrical wall 12, a flat top wall 13 and a flat bottom wall 14. A
25 vacuum pump 16 is csnnected by an exhaust line 17 to the interior of the chamber and operates to evacuate the chamber to a very low base pressure vacuum level (typically on the order o~ lO 6 Torr). As explained further below, the operating pressure within the c~amber ll is preferably on the order o~ lO 4 Torr. All of the walls 12, 13 and 14 maXing up the chamber ll are electrically connected together and connected by a line 18 to ground.
The target objest illustratively shown at 20 as a three-dimensional block is mounted substantially in the middle of the interior of the chamber li, spaced away from 129008~
all of the walls of the chamber, on a stage 21 at the enA
of a conductive support arm 22. The target 20 may assume a variety of shapes, including shapes having indentations and cavities. The target may be placed on 5 and removed from the stage 21 through a door (not sho~ln) formed in a conventional fashion in the enclosure wall 12 which, when closed, seals airtight to the wall and is also electrically connected ~o the walls to be at the same potential as the walls. It is a particular advantage of that a variety of complex shapes can be ion implanted without the need for a complex manipulation of either an ion beam or the target as required in conventional line of sight ion implantation, thereby eliminating the need for the conventional ion 15 accelerator stage, raster scan apparatus and target manipulator. The arm 22 holds the target 20 in a fixed position and is electrically in contact with it, as by a conductive clamp (not shown) on the stage 21. The arm may be covered with electrical insul~tion, if desired, or even shielded so that ions are not attracted to the arm. In addition, the support arm 22 may also be formed so that a coolant fluid is circulated through it to allow thermodynamic cooling of the target 20 during the ion implantation process to maintain the ~arget in substantial thermal equilibrium. Cooling of the target during implantation is desirable to minimize the thermal diffusion or ions away from the target surface. The conductive support arm 22 is electrically isolated, by an insulator 23, from the conductive wall 12 of the chamber through which it passes, and the insulator 23 is also formed to provide an air-tight seal to the wall 12 of the chamber. A high voltage, pul~e power supply 24 is used to provide the high voltage through a supply line 25 to the conductive support arm 22. The supply 24 provides repetitive pulses of high voltage, e.g.,`in the 20 kV to 100 kV range, of a duration selected as described below.
For example, the high voltage supply may be of the pulse line-pulse transformer type providing pulse lengths in the ~90~80 range of a few microseconds, or the supply may be chosen from various types of hig'n voltage tube modulated pulsers capable of providing relatively long pulse lengths in the s~ millisecond range or longer.~ / S r In accordance with this~r~ve~en, an ionized plasma is developed which surrounds the target 20 within the chamber 11 so that ions may be accelerated into the target from all sides. To develop the surrounding plasma, where a gas is to be used as the material to be implanted, a gas lo source 28 is connected by a line 29 to leak the qas at a low, controlled rate into the chamber 11 as it is being evacuated by the vacuum pump 16. Prior to ionization, there thus will be a low pressure atmosphere of the gas Irom the gas source 2~3 within the chamber 11 mixed with 15 very low levels of other impurity gases such as oxygen, etc. For purposes of illustration, the following description will assume that a source of nitrogen gas is provided from the gas source 28, although it will be apparent that many other source~ of ionizing ambient may 20 be provided using well known techniques, including sources provided by the vaporization of liquids and solids to form the ambient gas. The neutral gas within the chamber may be ionized in various ways. One method illustrated in Figs. 1 and 2 is the injection into the chamber of a 25 diffuse beam of electrons 30 from a heated filament electron source 31. The beam of electrons from the source 31 spreads through the interior of the chamber 11, colliding with the neutral gas to form ions. To maximize the collisions between the electrons ejected fro~ the source 31 and the ambient gas, magnet bars 32 are distributed about the outer periphery of the cylindrical side wall 12 of the chamber and magnetic pellets 33 are distributed over the top wall 13 and bottom wall 14.
Adjacent magnet bars 32 are oppositely poled--i.e., alternating north to south to north, etc.~-so that magnetic lines of force run between adjacent magnet bars within the interior of the chamber. Similarly, adjacent magnetic pellets 33 on the top and bottom walls of the ~ ~x~ov~
chamber are oppositely poled so that magnetic lines of force run into the chamber between these pellets. The magnetic field thus formed around the interior of the chamber adjacent to the walls of the chamber causes 5 electrons from the electron source to turn aroun~ as they approach the wall and move back into the interior of the chamber, where they may collide with gas atoms or molecules to ionize the gas.
Utilizing a multi-dipole filament Aischarge electron 10 source 31 at an operating pressure in the range of approximately 10 5 to 10 3 Torr, satisfactory plasmas are formed having a density of 106 to 1011 ions per cubic centimeter with an electron temperature of a few electron volts and an ion temperature of less than one 15 electron volt. Of course, it is readily apparent to those of ordinary s~ill that various other sources of ionizing radiation (e.g., radio frequency electromagnetic radiation) may be utilized to ionize the gas within the chamber 11 to form a plasma which surrounds the target object, A great variety of materials can be used as the target objects 20 for ion implantation in this manner, including pure metals and alloy metals such as steel, semiconductors, ceramics, and structural organic 25 polymers. Any of the various plasma sources well known in conventional ion implantation may be utilized as the source of the ions to be implanted, wi~h these ions being introduced into the chamber 11 to form a plasma which substantially surrounds the target object. These include gases such as nitrogen, argon, oxygen, and hydrogen. Ion mixing can also be obtained by t~chniques used in conventional ion implantation--for example, by evaporating boron and/or carbon layers on a substrate such as A12O3 followed by implantation with nitrogen ions.
Examples of sPecific implantation3 carried out using the inventive apparatus and method described below A target formed of a wafer of single crystal silicon of high purity was used as the target 20 mounted within ~" ,r 008~ `
the chamber 11 so that implantation would occur on one of the flat surfaces of the silicon. Nitrogen was used as the gas source introduced into the chamber 11, utilizing a multi-dipole filament discharge plasma source operating at 5 a neutral pressure of 2 x 10 4 Torr, resulting in an ion density of approximately 2 x 108 per cubic centimeter.
Pulses of voltage were provided from the high voltage supply 2~ have a peak pulse voltage between the walls of the chamber 11 and the target of approximately -25 kV.
lO The pulse duration was approximately 1 to 4 microseconds at a repetition rate of 60 Hz. The total implantation time during which pulses were applied to the target was 110 minutes. After implantation, the implanted surface of the silicon target substrate was e~amined using Auger 15 spectroscopy. The Auger measurement of nitrogen concentration versus depth from the silicon substrate surface for nitrogen ion implantations at a calculated average nitrogen ion energy at point of impact of 25 keV
is shown in the graph of Fig. 3. It is seen that the 20 percentage of nitrogen within the silicon crystal lattice increases up to a depth of approximately 400 Angstroms and gradually tails off with greater depth. Significant concentrations of nitrogen ions--in the 25 to 30 percent range--are found over a depth of approximately lO0 to 500 25 Angstroms from the surface of the silicon. This demonstrates substantial penetration of the nitrogen ions into the silicon bulk rather than the coating of ions onto the surface. It is also noted that the concentration of nitrogen ions is less at the surface of the silicon than 30 at depths below the surface up to 500 to 600 Angstroms.
In is thus seen that substrates of semicon~uctors such as silicon can be implanted with a selected dopant over a large surface area in a single implantation operation with masking being used in the normal manner, if desired, to 35 select the areas of the silicon substrate which are to be implanted.
The microhardness and tribological properties of materials may also be improved utilizing ion implantation 12Y0~80 carried out in accordance with the invention. As an example of the improvements which may be obtained in this manner, several type 5160 steel blocks were utilized as the taryet objects and were implanted in a nitrogen plasma 5 utilizing a multi-dipole filament discharge plasma source at a neutral pressure of 2 x 10 4 Torr and a resulting ion density of approximately 2 x 108 per cubic centimeter. The target was pulsed repetitively to a peak voltage o~ -40 kV to provide nitrogen ions having a peak energy of 40 keV at a total ion fluence of approximately 3 x 1017 per square centimeter of target surface area.
With reference to Fig. 4, the ion implanted specimen showed an increased Knoop hardness, as represented by the ~raph 40, which is approximately 25 percent greater than 15 the a5 received material shown by the graph 41. Hea~
treatment of the blocks alone showed the Knoop hardness represented by the graph 42 in Fig. 4. However, the combination of heat treatment followed by ion implantation of the blocks resulted in the Knoop hardness represented by the graph 43 of Fig. 4, a doubling of the Knoop hardness over -the as received material. Block on ring wear tests (ASTM standard practice G77-83) show an improvement in the wear resistance of ion implanted and heat treated 5160 steel specimens of approximately 50 over as-received samples.
Improved wear resistance has also been obtained for precipitation hardened Invar (microhardness doubled at light loads, wear resistance improved by 250%), M2 tool steel punches, and ceramic cutting tool inserts (AL2O3 with SiC whisker crystals, more than a doubLing of tool lifetime obtained). Electrical conductivity of organic polymer plastic (~apton-H) has been modified by ion implantation.
It is a particular advantage of the plasma source ion 3~ implantation process to utilize separa~e voltage sources for the high voltage pulse power supply 24 and for the electron source 31 which provides the ionizing radiation since the use of the two separate sources allows the z9~
plasma density to be adjusted independently of the acceleration energy. ~le nature o the high vGltage pulse provided from the supply 24 between the target 20 and the surrounding enclosure walls 12 is a significant process S condition for two reasons. First, a relatively short duty cycle (pulse width times the repetition rate) minimizes or eliminates surface damage to the target from sustained high voltage arcing. Second, as explained more fully below, the relatively short pulse width of the repetitive 10 pulses applied in the process of this invention provides spatial uniformity and imp]antation depth uniformity by chosing the pulse width such that the plasma sheath which forms around the target does not expand sufficiently during the time of the applied voltage pulse to contact 15 either the chamber enclosure walls or the sheath which surrounds adjacent targets if multiple targets are being implanted. The reasons for these criteria for the acceleration voltage pulse width can be best understood by considering the dynamics of the plasma sheath which surrounds the target or targets during plasma source ion implantation.
When a large negative potential pulse is applied to a target electrode (such as a target ob~ect 20) immersed in a plasma, a plasma sheath forms around the electrode. The 25 plasma sheath is a region, between a quasi-charge neutral plasma and an electrode, in which charge neutrality is violated. Three time scales govern the dynamic response of the sheath. Just prior to the application of the voltage pulse, at time t = 0, the electrode is at zero 30 potential. As the voltage pulse is applied to the electrode and the potential of the electrode increases to the maximum negative potential, electrons are expelled from a region near the electrode. This expulsion occurs rapidly on a time scale governed by the inverse electron 35 plasma frequency. During this initial expulsion of electrons, the much heavier ions experience negligible motion so that as the electrons are repulsed, they leave behind a region of nearly uniform ion space charge. This 29~(~B(~
positive space cha~ge region establishes a potential profile which can be described by an ion-matrix model.
Later on during application of the voltage pulse, on a slower time scale governed by the inverse ion plasma 5 frequency, ions are accelerated toward the electrodè as they fall through the ion-matrix sheath. At a later time during the application of the pulse, on a much longer time scale (much greater than the inverse ion plasma ~requency), the decreasing ion density inside the sheath 10 region causes a corresponding decrease in the electron density, and consequently the sheath edge expands outwardly at approximately the plasma ion acoustic velocity. The thickness of the initial ion-matrix sheath can be calculated based on a theoretical analysis of 15 sheath physics for various target geometriesO The expansion rate of the sheath can be calculated from the standard expression for the ion acoustic velocity in a plasma.
The ion-matrix sheath thickness is determined by the 20 plasma density, target radius of curvature, and applied implantation potential. The subsequent sheath expansion depends on the plasma electron temperature and the ion mass. For example, for implantation of nitrogen ions into a cylinder of 1 centimeter radius, at a potential of 100 25 ~;ilovolts, the initial ion-matrix sheath forms at a radius of four centimeters from the central axis of the target cylinder, and the sheath expands at an ion acoustic velocity of 0.25 centimeters per microsecond. The pulse length of the plasma source ion implantation waveform should be chosen to be short enough that the expanding sheath does not contact either the vacuum chambex wall or th~ sheath w'nich surrounds an adjacent target if multiple targets are being implanted. For example, if the pulse length is chosen to be 30 microseconds, the sheath will 35 expand to an ultimate radius of 11.5 centimeters, thus re~uiring that the enclosure wall surrounding the target be at least that distance from the central axis of the target.
-lX90~0 For a given ion density, acceleration potential, and target radius of curvature, it is found that the ion-matrix sheath thickness is larger for a cylindrical target than for a spherical target. Thus, the cylindrical 5 target may be considered the worst case for purposes of determining the target spacing required for multiple targets. For illustration, four cylindrical targets are shown at 50 in Fig. 5 in simplified perspective view, supported on support arms 51 which also transmit the 10 voltage pulse to the targets. The targets 50 are equally spaced from one another in a matrix at a spacing which will be denoted 2D, as illustrated in Fig. 6. In Fig. 6, the cylindrical target 50 has a radius rO, the initial ion-matrix sheath illustrated by the dashed line labeled 15 53 has a radius which will be denoted as rsO, and the expanding sheath edge illustrated by the dashed line labeled 54 in Fig. 6 has a radius which will be denoted as rs. Using this nomenclature, the expression for the expansion of the sheath may be written as rS - rS0 +
20 Cst, where rs0, the initial ion matrix sheath thickness, is calculated from an analysis of the sheath physics, Cs is sheath acoustic speed, and t is pulse length. Fig. 7 illustxates graphs which allow calculation of the initial ion matrix sheath thickness rsO for 25 plane, cylindrical and spherical electrodes (or targets).
The graphs of Fig. 7 show the ratio of the sheath radius to the electrode (target) radius for cylindrical spherical targets as a function of the quantity ~Ojr2O, a dimensionless parameter. That parameter may be expressed in terms of physical quantities as follows:
/r2O = ~O/(4~n~erO) = 5.53 x 105(~0/nOrO) where rO is the target radius, ~0 i5 the applied potential, nO is the plasma density, and e is ~he electron chargeO
For planar targets, the potential is translationally invariant and the electrode position rO can be set to ~ero, and the expression for sheath radius reduces to rS
= (2~o) / where rS = rS/~ D' 0O =
1~9~
e~0/T ; ~2 = Te/(4 ~ nOe2), and T is electron temperature.
To satisfy the condition that the expandin~ sheath surrounding adjacent targets just merge at the end of the 5 pulse time, rS will be equal to D, which implies that the pulse length t = (D - rsO)/Cs. The maximum pulse length for a single target can be calculated in a similar manner if it is assumed that the distance D is the distance to the walls of the chamber surrounding a single lO target. Of course, the distance of the outermost of multiple targets should be sufficiently distant ~rom the chamber walls that the sheath will not reach the wall during a pulse.
The fluence F per pulse can be calculated from the 15 following expression:
F = n0(rs ~ rO)/rO 2 which is approximately equal to nOrS/rO if rO ~< rS~ a condition that is satisfied for targets with relatively small radii.
A significant limitation on the pulse repetition rate is the amount of average power that can be absorbed by the targets so that a satisfactory thermal equilibrium is maintained by the targets. The average power HaVg per unit area of target can be found from the expression HaVg = e~OF/T
~here ~0 is the applied voltage, e is the electron charge, F is the fluence, and T is the time spacing between the trailing edge of one pulse and the leading edge of the next pulse.
As an example, assume it i5 desired to keep the average power per unit area less than five watts per square centimeter. Assume ~urther the following typical values for the operating conditions: plasma density n =
10l per cubic centimeter, applied potential ~0 = lO0 35 kV, ion acoustic velocity Cs = 0.25 centimeters per microsecond, and cylindrical target radius rO = l centimeter. The calculated Debye length '~ D = 0.01 centimeter, the normalized electrode radius rO = rO/ ~ D
will thus equal lO0, the normalized potential will be equal to 50,000 and the dimensionless sheath scaling parameter ~0/rO will equal to 5. From Fig. 7, the ratio f of sheath radius to electrode radius ~ill equal 4, providing an initial sheath radius rsO = 4 centimeters.
5 Choosing a pulse length t = 30 microseconds, the ultimate sheath radius at the end of the pulse will be 11.5 centimeters, requiring a cell spacing 2D equal to 23 centimeters on centers of the multiple targets. The fluence F per pulse will be 1.3 x 10 per square lo centimeter. To achieve a total fluence of 5 x 1017 per square centimeter, 4 x 105 pulses are thus required.
The time T between pulses dictated by cooling considerations will thus be equal to T = e~OF/H
(1.6 x 10 19 coulombs) (105V) (1.3 x 1012cm 2)/(5 15 watts/cm ~ = 4.2 milliseconds, which is much greater than the pulse length t which is equal to 30 microseconds.
If it were assumed that the current is substantially constant during the pulse (not necessarily a practical assumption), the conduction current density for the foregoing example would be (1.6 x 10 19 coulombs) (1.3 x 1012 cm 2/(30 microseconds) = 0.007 amperes/cm2.
Assuming the targets are a matrix of 50 cylinders having a length equal to 5 centimeters and a radius of 1 centimeter, the peak conduction current would then be 50 x 2 1r (1 cm)(5 cm)(0.007 A/cm ) = 11 A.
0~ course, it shoul-l be understood that the peak current at the beginning of the pulse is greater than this average current due to displacement current and transient sheath effects.
The average conduction current is (11 A) x (30 microseconds)/(4.2 milliseconds~ = 80 mA, and the average power is 100 XV x 80 mA = 8 kW.
The total implantation time for the foregoing example would thus be equal to: (4 x 105 pulses) (4.23 35 milliseconds) = 1692 seconds = 28.2 minutes.
The square array of 50 targets (actually, a 7 by 7 array or 49 targets) would occupy a square 160 centimeters on a side, or an area of 2.6 square meters.
8~ `
From the foregoing example, it may be seen that the desi.red geometrical packing between multiple targets or between a single target and the walls of t'ne enclosure determines the pulse length, whereas the total 5 implantation time is determined by the time T between pulses which is constrained by the ability to cool the target during implantation.
Using the conditions of the above example, the relationship of the chosen pulse length to the required 10 cell spacing and vacuum chamber area is illustrated below in Table 1.
Area of Vacuum Chamber Pulse Length Cell Spacing 2D Base for a 7 x 7 Array 15 ( ~ sec) (cm) of Tools ~m2) _________________ ________ _____________ __________________ 1013 0.8 2018 1.6 3023 2.6 205033 5.3 10058 16.5 From the data above, it seen that the chamber area increases rapidly and nonlinearly as the pulse length increases, increasing roughly as the square of the pulse 25 length.
Again using the conditions from the foregoing example, the effect of changes in the plasma density, keeping other factors constant, is illustrated below in Table 2.
~ 2 density .~ r ~ /r Initial Sheath D o o oRadius (cm~3) (cm) (cm) _ 109 0.03330 60.0 10.0 101 0.010100 5.0 4.0 1011 0.0033300 0.6 2.0 (continued below) ~2~080 Area of a Sheath Radius Fluence Off-time Cell Spacing 7x7 Array at t=30 sec per T 2D o~ tools (cm) pulse (msec)(cm) ~m2) .
518.0 3.2xlOll 1.0 36 6.5 11.5 1.3x1012 4.2 23 2.6 9.5 9.0~1012 29.0 19 1.8 It is seen that with cylindrical targets there is an advantage to increasing the plasma density as much as possible. In addition to the more favorable size scaling noted above, higher plasma density will provide more uni~orm implantation i~ the target has less than per~ct cylindrical symmetry.
Implantation may also 15 be accomplished with planar targets. Assuming a relatively large planar target in which loading effects are not significant, it may be shown that the maximum pulse length is determined only by the dimension of the vacuum chamber in the direction normal to the target 20 plane. The normalized planar sheath thic~nes~ may be calculated as:
d - rS0/ ~D = (2po) /
so that the initial sheath position is:
rsO e (2~o)l/2 ~D= (2~o)l/ x 743 (Te/n) /
For T = 2 eVj and ~0 = 100 kV, this gives rsO =
FIELD OF THE INVENTION
This invention pertains qenerally to the field of surface treatment and paxticularly to surface treatment by 5 ion implantation techniques.
BACKGROUND OF THE INVENTION
Ion implantation offers great commercial promi-se for the improvement of the surface characteristics of a variety o~ materials, including metals, ceramics and 10 plastics. In the conventional ion implantation process, ions are formed into a beam and accelerated to high energy before being directed into the surace of a solid target.
Because the ion implantation process is not limited by the thermodyn~mic constraints of more conventional techniques, 15 ion implantation allows new materials to be produced with new surface properties. In particular, implantation can be used to improve greatly the friction, wear and corrosion resistance properties of the surfaces of metals. For example, implantation of nitrogen ions in a 20 titanium alloy artificial hip joint has increased the joint lifetime by a factor of 400 or more. The properties of ceramic components and ceramic cutting tools can also be improved by ion implantation. For a general discussion of the techniques and potential advantages of ion implantation, see generally S. Picraux, et al., "Ion Implantation of Surfaces", Scientific American, Vol. 252, No. 3, pp. 102-113, 1985; D.M. Hulett, et al., "lon 5 Nitriding and Ion Implantation: A Comparison," Metal Progress, August 1985, pp. 18-21; V.M. Cassidy, "Ion Implantation Process rroughens Metalworking Tools," Modern ~letals, Septe~ber 1984, pp. 65-67.
While commercially viable applications of conventional 10 ion implantation techniques have been demonstrated, the relatively high cost of the process has limited its use thus far to high unit cost items having very special applications. A significant factor in the substantial production costs of conventional ion implantation is that 15 significant and time-consuming manipulation of the ion beam and the target is required to obtain implantation over the entire surface of a three-dimensional target. In conventional ion implantation, the ions are extracted from a plasma source and focused into a beam which is 20 accelerated to the desired energy and then rastered across one face of the target to uniformly implant the surface of that face. Because of the line of sight nature of this ion implantation techni~ue, a manipulator platform or stage is required which can support the target for 25 rotation in the beam so that all sides of the target can be implanted. The need to manipulate a three-dimensional target to allow all sides of the target to be implanted adds cost and complexity, constrains the maximum size of the target which can be-implanted, and increases the total 30 time required to obtain satisfactory implantation of all target surfaces for relatively large targets. Because the ions travel to the target in a largely unidirectional beam, it is often necessary to mask targets having convex surfaces so that ions are allowed to strike the target 35 only at angles substantially normal to the target surface. Normal incidence of ions to the surface is preferred since as the difference in the angle of 8~
incidence from the normal increases, sputtering increases and the net retained dose in the target decreases.
The present disclosure is directed to significantly improved 5 production efficiencies in ion implantation o three-dimensional materials by achieving implantation from all sides of ~he target simultaneously. Consequently, the production eficiensy for implantation of three~dimensional objects is greatly increased over conventional ion implantation techniques. Since the target need not be manipulated, complicated target manipulation apparatus is not required.
In plasma source ion implantation here described, the target to be implanted is ~urrounded by the plasma source within an evacuated chamber. A high negative potential pulse is then applied to the target relative to the walls o~ the chamber to accelerate iOllS from the plasma across the plasma sheath toward the target in directions s~bstantially normal to the sur~aces of the target at the points where the ions impinge upon the surface. The high voltage pulse, e.y., typically 20 kilovolts (kV) or higher, causes the.ions to be driven deeply into the target object, typically causing ions to be distributed into the cry~tal lattice of the target to form a modified material layer over all exposed sur~aces of the taxget object. Multiple pulses may be applisd between the taxget and the chamber walls in rapid succession to perform multiple implantation until a desired concentration of implanted ions within the target object is achieved.
Preferably, the ion source plasma surrounding the target object is formed by introducing the ion source material in a gas or vapor orm into the highly evacuated space within the confining chamber. The gaseous material may then be ionized by directing ionizing radiation, such as a difuse beam of electrons, through the source gas in a conventional manner. Consequently, a plasma of ions is formed which completely surrounds the target object itself so that ions may b~ implanted into the target from all sides, if desired.
Multiple targets, properly spaced within the plasma, may be implanted simultaneously in accordance with the invention.
Utilizing the new ion implantation process and apparatus, ion implantations may be performed on complex, three-dimensional objects formed of a great variety of materials, including pure metals, alloys, semi-conductors, ceramics, and organic polymers. signi~icant increases in surface hardness are obtained with ion implantation o~ a variety o~ source materials, including gases such as nitrogen, into metal and ceramic surfaces. Ion implantation of organic plastic materials can produce desirable surface characteristic modifications including a change in the optical properties and the electrical conductivity of the polymer. Ion implantation is also found to be particularly beneficial when used in con~unction with conventional heat treatment hardening techniques. Metal objects which have been both ion implanted in accordance with the new process and apparatus and heat treated are found to exhibit significantly greater hardness and resistance to wear than objects which are only heat treated or ion implanted, but not both.
More particularly, in accordance with a first aspect of the invention there is provided a method of implanting ions from a plasma into a target object comprising the steps of:
~ a) positioning the target object in an enclosing chamber;
(b~ generating a plasma of ions which surrounds the target object;
(c~ then, independently from generating the plasma, applying a high negative voltage pulse to the target object to accelerate the ions in the plasma toward the target from the plasma surrounding the target at an ion enPrgy sufficient to implant ions impacting the target object beneath the surface of and into the crystal lattice of the target objsct.
3L~9V08~
- 4a -In accordance with a second aspect of the invention there is provided a method of implanting ions in a target object comprising the st~ps of:
(a) providing an enclosing chamber having walls of electrically conductive material:
(b) suspending a target object within the chamber ~paced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) i~dependently of forming the plasma, applying a pulse o~ high voltage between the chamber walls and the target object at a voltage suffizient to implant ions from the plasma into the target object.
In accordance with a third asp~ct of the invention there is provided a method of implanting ions in a target object comprising the steps of:
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a target object within the chamber spaced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) applying repetitive pulses of high voltage between the chamber walls and the target object independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target object, the width of the pulsPs being ~elected such that the plasma sheath surrounding the target object does not expand to contact the enclosure walls during the pulse.
In accordance with a fourth aspect of the invention there is provided a method of implanting ions in a target object csmprising the steps of:
(a) providing an enclosing chamber having walls of electrically conductive material;
, , 12~013~
- 4b -(b) suspending a plurality of target objects within the chamber spaced away from the walls of the chamber and from each other;
(c) evacuating the interior of the chamber to a ve~y low base pressure;
(d) forming a plasma of ions in the chamber around the target objects;
(e) applying repetitive pulses of high voltage between the chamber walls and the target objects independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target objects, the width of each pulse of high voltage selected such that the plasma sheath surrounding each target object does not expand during the pulse to contact the plasma sheath surrounding another target object or to contact the walls of the chamber.
In accordance with a fifth aspect of the invention there is provided an apparatus for implanting ions in a target object comprising:
(a) electrically conductive enclosure walls defining an enclosing chamber surrounding a sealed space;
(b) means for supporting a target object within the enclosing chamber at a position spaced away from and electrically isolated from the enclosure walls of the chamber and for providing an electrical connection between the target object so supported and the exterior of the chamber;
(c) means for forming a plasma of ions of a selected material within the enclosing chamber around the target object;
(d) means for evacuating the interior of the enclosing chamber to a desired low pressure level; and (e) means, independent of the means for forming a plasma, for applying a pulse of voltage between the enclosure walls and the target object sufficient to implant ions from the plasma into the target object.
Embodiments of the invention will now be described with reference to the accompanying drawings in which:
Fig. 1 is a simplified cross-sectional view through an ion implantation chamber with associated apparatus embodying the present invention.
Fig. 2 is a cross-section through the ion implantation chamber of Fig. 1 taken generally along the lines 2-2 of Fig. 1.
900~30 Fig 3 is a graph showing Auger measurements of nitrogen ion concen~ration versus depth for a silicon target implanted with 25 keV nitrogen ions.
Fig. 4 is a graph showing Knoop hardness or a 5160 5 steel target for a sample as received, with ion implantation alone, with heat treatment alone, and with heat treatment and ion implantation.
~ ig. 5 i8 a simpli~ied perspective view o~ several identical cylindrical targets mounted within the ion lO implantation chamber to be implanted simultaneously.
Fig. 6 i a schematic view iLlustrating the spacing requirements ~or multiple cylindrical targets in the ion implantation chamber.
Fig. 7 are graphs showing calculated spacing 15 requirements for planar, cylindrical and spherical targets under various implantation conditions.
DESCRIPTIOM OF THE PREFERRED EMBODIMENTS
With reference to the drawings, an ion implantation apparatus is shown generally at lO in partial cross-section in Fig. l.
The apparatus 10 includes an enclosing chamber ll having conductive walls, e.g., of stainless steel or aluminum, which may be ~ormed, as shown, with an outer cylindrical wall 12, a flat top wall 13 and a flat bottom wall 14. A
25 vacuum pump 16 is csnnected by an exhaust line 17 to the interior of the chamber and operates to evacuate the chamber to a very low base pressure vacuum level (typically on the order o~ lO 6 Torr). As explained further below, the operating pressure within the c~amber ll is preferably on the order o~ lO 4 Torr. All of the walls 12, 13 and 14 maXing up the chamber ll are electrically connected together and connected by a line 18 to ground.
The target objest illustratively shown at 20 as a three-dimensional block is mounted substantially in the middle of the interior of the chamber li, spaced away from 129008~
all of the walls of the chamber, on a stage 21 at the enA
of a conductive support arm 22. The target 20 may assume a variety of shapes, including shapes having indentations and cavities. The target may be placed on 5 and removed from the stage 21 through a door (not sho~ln) formed in a conventional fashion in the enclosure wall 12 which, when closed, seals airtight to the wall and is also electrically connected ~o the walls to be at the same potential as the walls. It is a particular advantage of that a variety of complex shapes can be ion implanted without the need for a complex manipulation of either an ion beam or the target as required in conventional line of sight ion implantation, thereby eliminating the need for the conventional ion 15 accelerator stage, raster scan apparatus and target manipulator. The arm 22 holds the target 20 in a fixed position and is electrically in contact with it, as by a conductive clamp (not shown) on the stage 21. The arm may be covered with electrical insul~tion, if desired, or even shielded so that ions are not attracted to the arm. In addition, the support arm 22 may also be formed so that a coolant fluid is circulated through it to allow thermodynamic cooling of the target 20 during the ion implantation process to maintain the ~arget in substantial thermal equilibrium. Cooling of the target during implantation is desirable to minimize the thermal diffusion or ions away from the target surface. The conductive support arm 22 is electrically isolated, by an insulator 23, from the conductive wall 12 of the chamber through which it passes, and the insulator 23 is also formed to provide an air-tight seal to the wall 12 of the chamber. A high voltage, pul~e power supply 24 is used to provide the high voltage through a supply line 25 to the conductive support arm 22. The supply 24 provides repetitive pulses of high voltage, e.g.,`in the 20 kV to 100 kV range, of a duration selected as described below.
For example, the high voltage supply may be of the pulse line-pulse transformer type providing pulse lengths in the ~90~80 range of a few microseconds, or the supply may be chosen from various types of hig'n voltage tube modulated pulsers capable of providing relatively long pulse lengths in the s~ millisecond range or longer.~ / S r In accordance with this~r~ve~en, an ionized plasma is developed which surrounds the target 20 within the chamber 11 so that ions may be accelerated into the target from all sides. To develop the surrounding plasma, where a gas is to be used as the material to be implanted, a gas lo source 28 is connected by a line 29 to leak the qas at a low, controlled rate into the chamber 11 as it is being evacuated by the vacuum pump 16. Prior to ionization, there thus will be a low pressure atmosphere of the gas Irom the gas source 2~3 within the chamber 11 mixed with 15 very low levels of other impurity gases such as oxygen, etc. For purposes of illustration, the following description will assume that a source of nitrogen gas is provided from the gas source 28, although it will be apparent that many other source~ of ionizing ambient may 20 be provided using well known techniques, including sources provided by the vaporization of liquids and solids to form the ambient gas. The neutral gas within the chamber may be ionized in various ways. One method illustrated in Figs. 1 and 2 is the injection into the chamber of a 25 diffuse beam of electrons 30 from a heated filament electron source 31. The beam of electrons from the source 31 spreads through the interior of the chamber 11, colliding with the neutral gas to form ions. To maximize the collisions between the electrons ejected fro~ the source 31 and the ambient gas, magnet bars 32 are distributed about the outer periphery of the cylindrical side wall 12 of the chamber and magnetic pellets 33 are distributed over the top wall 13 and bottom wall 14.
Adjacent magnet bars 32 are oppositely poled--i.e., alternating north to south to north, etc.~-so that magnetic lines of force run between adjacent magnet bars within the interior of the chamber. Similarly, adjacent magnetic pellets 33 on the top and bottom walls of the ~ ~x~ov~
chamber are oppositely poled so that magnetic lines of force run into the chamber between these pellets. The magnetic field thus formed around the interior of the chamber adjacent to the walls of the chamber causes 5 electrons from the electron source to turn aroun~ as they approach the wall and move back into the interior of the chamber, where they may collide with gas atoms or molecules to ionize the gas.
Utilizing a multi-dipole filament Aischarge electron 10 source 31 at an operating pressure in the range of approximately 10 5 to 10 3 Torr, satisfactory plasmas are formed having a density of 106 to 1011 ions per cubic centimeter with an electron temperature of a few electron volts and an ion temperature of less than one 15 electron volt. Of course, it is readily apparent to those of ordinary s~ill that various other sources of ionizing radiation (e.g., radio frequency electromagnetic radiation) may be utilized to ionize the gas within the chamber 11 to form a plasma which surrounds the target object, A great variety of materials can be used as the target objects 20 for ion implantation in this manner, including pure metals and alloy metals such as steel, semiconductors, ceramics, and structural organic 25 polymers. Any of the various plasma sources well known in conventional ion implantation may be utilized as the source of the ions to be implanted, wi~h these ions being introduced into the chamber 11 to form a plasma which substantially surrounds the target object. These include gases such as nitrogen, argon, oxygen, and hydrogen. Ion mixing can also be obtained by t~chniques used in conventional ion implantation--for example, by evaporating boron and/or carbon layers on a substrate such as A12O3 followed by implantation with nitrogen ions.
Examples of sPecific implantation3 carried out using the inventive apparatus and method described below A target formed of a wafer of single crystal silicon of high purity was used as the target 20 mounted within ~" ,r 008~ `
the chamber 11 so that implantation would occur on one of the flat surfaces of the silicon. Nitrogen was used as the gas source introduced into the chamber 11, utilizing a multi-dipole filament discharge plasma source operating at 5 a neutral pressure of 2 x 10 4 Torr, resulting in an ion density of approximately 2 x 108 per cubic centimeter.
Pulses of voltage were provided from the high voltage supply 2~ have a peak pulse voltage between the walls of the chamber 11 and the target of approximately -25 kV.
lO The pulse duration was approximately 1 to 4 microseconds at a repetition rate of 60 Hz. The total implantation time during which pulses were applied to the target was 110 minutes. After implantation, the implanted surface of the silicon target substrate was e~amined using Auger 15 spectroscopy. The Auger measurement of nitrogen concentration versus depth from the silicon substrate surface for nitrogen ion implantations at a calculated average nitrogen ion energy at point of impact of 25 keV
is shown in the graph of Fig. 3. It is seen that the 20 percentage of nitrogen within the silicon crystal lattice increases up to a depth of approximately 400 Angstroms and gradually tails off with greater depth. Significant concentrations of nitrogen ions--in the 25 to 30 percent range--are found over a depth of approximately lO0 to 500 25 Angstroms from the surface of the silicon. This demonstrates substantial penetration of the nitrogen ions into the silicon bulk rather than the coating of ions onto the surface. It is also noted that the concentration of nitrogen ions is less at the surface of the silicon than 30 at depths below the surface up to 500 to 600 Angstroms.
In is thus seen that substrates of semicon~uctors such as silicon can be implanted with a selected dopant over a large surface area in a single implantation operation with masking being used in the normal manner, if desired, to 35 select the areas of the silicon substrate which are to be implanted.
The microhardness and tribological properties of materials may also be improved utilizing ion implantation 12Y0~80 carried out in accordance with the invention. As an example of the improvements which may be obtained in this manner, several type 5160 steel blocks were utilized as the taryet objects and were implanted in a nitrogen plasma 5 utilizing a multi-dipole filament discharge plasma source at a neutral pressure of 2 x 10 4 Torr and a resulting ion density of approximately 2 x 108 per cubic centimeter. The target was pulsed repetitively to a peak voltage o~ -40 kV to provide nitrogen ions having a peak energy of 40 keV at a total ion fluence of approximately 3 x 1017 per square centimeter of target surface area.
With reference to Fig. 4, the ion implanted specimen showed an increased Knoop hardness, as represented by the ~raph 40, which is approximately 25 percent greater than 15 the a5 received material shown by the graph 41. Hea~
treatment of the blocks alone showed the Knoop hardness represented by the graph 42 in Fig. 4. However, the combination of heat treatment followed by ion implantation of the blocks resulted in the Knoop hardness represented by the graph 43 of Fig. 4, a doubling of the Knoop hardness over -the as received material. Block on ring wear tests (ASTM standard practice G77-83) show an improvement in the wear resistance of ion implanted and heat treated 5160 steel specimens of approximately 50 over as-received samples.
Improved wear resistance has also been obtained for precipitation hardened Invar (microhardness doubled at light loads, wear resistance improved by 250%), M2 tool steel punches, and ceramic cutting tool inserts (AL2O3 with SiC whisker crystals, more than a doubLing of tool lifetime obtained). Electrical conductivity of organic polymer plastic (~apton-H) has been modified by ion implantation.
It is a particular advantage of the plasma source ion 3~ implantation process to utilize separa~e voltage sources for the high voltage pulse power supply 24 and for the electron source 31 which provides the ionizing radiation since the use of the two separate sources allows the z9~
plasma density to be adjusted independently of the acceleration energy. ~le nature o the high vGltage pulse provided from the supply 24 between the target 20 and the surrounding enclosure walls 12 is a significant process S condition for two reasons. First, a relatively short duty cycle (pulse width times the repetition rate) minimizes or eliminates surface damage to the target from sustained high voltage arcing. Second, as explained more fully below, the relatively short pulse width of the repetitive 10 pulses applied in the process of this invention provides spatial uniformity and imp]antation depth uniformity by chosing the pulse width such that the plasma sheath which forms around the target does not expand sufficiently during the time of the applied voltage pulse to contact 15 either the chamber enclosure walls or the sheath which surrounds adjacent targets if multiple targets are being implanted. The reasons for these criteria for the acceleration voltage pulse width can be best understood by considering the dynamics of the plasma sheath which surrounds the target or targets during plasma source ion implantation.
When a large negative potential pulse is applied to a target electrode (such as a target ob~ect 20) immersed in a plasma, a plasma sheath forms around the electrode. The 25 plasma sheath is a region, between a quasi-charge neutral plasma and an electrode, in which charge neutrality is violated. Three time scales govern the dynamic response of the sheath. Just prior to the application of the voltage pulse, at time t = 0, the electrode is at zero 30 potential. As the voltage pulse is applied to the electrode and the potential of the electrode increases to the maximum negative potential, electrons are expelled from a region near the electrode. This expulsion occurs rapidly on a time scale governed by the inverse electron 35 plasma frequency. During this initial expulsion of electrons, the much heavier ions experience negligible motion so that as the electrons are repulsed, they leave behind a region of nearly uniform ion space charge. This 29~(~B(~
positive space cha~ge region establishes a potential profile which can be described by an ion-matrix model.
Later on during application of the voltage pulse, on a slower time scale governed by the inverse ion plasma 5 frequency, ions are accelerated toward the electrodè as they fall through the ion-matrix sheath. At a later time during the application of the pulse, on a much longer time scale (much greater than the inverse ion plasma ~requency), the decreasing ion density inside the sheath 10 region causes a corresponding decrease in the electron density, and consequently the sheath edge expands outwardly at approximately the plasma ion acoustic velocity. The thickness of the initial ion-matrix sheath can be calculated based on a theoretical analysis of 15 sheath physics for various target geometriesO The expansion rate of the sheath can be calculated from the standard expression for the ion acoustic velocity in a plasma.
The ion-matrix sheath thickness is determined by the 20 plasma density, target radius of curvature, and applied implantation potential. The subsequent sheath expansion depends on the plasma electron temperature and the ion mass. For example, for implantation of nitrogen ions into a cylinder of 1 centimeter radius, at a potential of 100 25 ~;ilovolts, the initial ion-matrix sheath forms at a radius of four centimeters from the central axis of the target cylinder, and the sheath expands at an ion acoustic velocity of 0.25 centimeters per microsecond. The pulse length of the plasma source ion implantation waveform should be chosen to be short enough that the expanding sheath does not contact either the vacuum chambex wall or th~ sheath w'nich surrounds an adjacent target if multiple targets are being implanted. For example, if the pulse length is chosen to be 30 microseconds, the sheath will 35 expand to an ultimate radius of 11.5 centimeters, thus re~uiring that the enclosure wall surrounding the target be at least that distance from the central axis of the target.
-lX90~0 For a given ion density, acceleration potential, and target radius of curvature, it is found that the ion-matrix sheath thickness is larger for a cylindrical target than for a spherical target. Thus, the cylindrical 5 target may be considered the worst case for purposes of determining the target spacing required for multiple targets. For illustration, four cylindrical targets are shown at 50 in Fig. 5 in simplified perspective view, supported on support arms 51 which also transmit the 10 voltage pulse to the targets. The targets 50 are equally spaced from one another in a matrix at a spacing which will be denoted 2D, as illustrated in Fig. 6. In Fig. 6, the cylindrical target 50 has a radius rO, the initial ion-matrix sheath illustrated by the dashed line labeled 15 53 has a radius which will be denoted as rsO, and the expanding sheath edge illustrated by the dashed line labeled 54 in Fig. 6 has a radius which will be denoted as rs. Using this nomenclature, the expression for the expansion of the sheath may be written as rS - rS0 +
20 Cst, where rs0, the initial ion matrix sheath thickness, is calculated from an analysis of the sheath physics, Cs is sheath acoustic speed, and t is pulse length. Fig. 7 illustxates graphs which allow calculation of the initial ion matrix sheath thickness rsO for 25 plane, cylindrical and spherical electrodes (or targets).
The graphs of Fig. 7 show the ratio of the sheath radius to the electrode (target) radius for cylindrical spherical targets as a function of the quantity ~Ojr2O, a dimensionless parameter. That parameter may be expressed in terms of physical quantities as follows:
/r2O = ~O/(4~n~erO) = 5.53 x 105(~0/nOrO) where rO is the target radius, ~0 i5 the applied potential, nO is the plasma density, and e is ~he electron chargeO
For planar targets, the potential is translationally invariant and the electrode position rO can be set to ~ero, and the expression for sheath radius reduces to rS
= (2~o) / where rS = rS/~ D' 0O =
1~9~
e~0/T ; ~2 = Te/(4 ~ nOe2), and T is electron temperature.
To satisfy the condition that the expandin~ sheath surrounding adjacent targets just merge at the end of the 5 pulse time, rS will be equal to D, which implies that the pulse length t = (D - rsO)/Cs. The maximum pulse length for a single target can be calculated in a similar manner if it is assumed that the distance D is the distance to the walls of the chamber surrounding a single lO target. Of course, the distance of the outermost of multiple targets should be sufficiently distant ~rom the chamber walls that the sheath will not reach the wall during a pulse.
The fluence F per pulse can be calculated from the 15 following expression:
F = n0(rs ~ rO)/rO 2 which is approximately equal to nOrS/rO if rO ~< rS~ a condition that is satisfied for targets with relatively small radii.
A significant limitation on the pulse repetition rate is the amount of average power that can be absorbed by the targets so that a satisfactory thermal equilibrium is maintained by the targets. The average power HaVg per unit area of target can be found from the expression HaVg = e~OF/T
~here ~0 is the applied voltage, e is the electron charge, F is the fluence, and T is the time spacing between the trailing edge of one pulse and the leading edge of the next pulse.
As an example, assume it i5 desired to keep the average power per unit area less than five watts per square centimeter. Assume ~urther the following typical values for the operating conditions: plasma density n =
10l per cubic centimeter, applied potential ~0 = lO0 35 kV, ion acoustic velocity Cs = 0.25 centimeters per microsecond, and cylindrical target radius rO = l centimeter. The calculated Debye length '~ D = 0.01 centimeter, the normalized electrode radius rO = rO/ ~ D
will thus equal lO0, the normalized potential will be equal to 50,000 and the dimensionless sheath scaling parameter ~0/rO will equal to 5. From Fig. 7, the ratio f of sheath radius to electrode radius ~ill equal 4, providing an initial sheath radius rsO = 4 centimeters.
5 Choosing a pulse length t = 30 microseconds, the ultimate sheath radius at the end of the pulse will be 11.5 centimeters, requiring a cell spacing 2D equal to 23 centimeters on centers of the multiple targets. The fluence F per pulse will be 1.3 x 10 per square lo centimeter. To achieve a total fluence of 5 x 1017 per square centimeter, 4 x 105 pulses are thus required.
The time T between pulses dictated by cooling considerations will thus be equal to T = e~OF/H
(1.6 x 10 19 coulombs) (105V) (1.3 x 1012cm 2)/(5 15 watts/cm ~ = 4.2 milliseconds, which is much greater than the pulse length t which is equal to 30 microseconds.
If it were assumed that the current is substantially constant during the pulse (not necessarily a practical assumption), the conduction current density for the foregoing example would be (1.6 x 10 19 coulombs) (1.3 x 1012 cm 2/(30 microseconds) = 0.007 amperes/cm2.
Assuming the targets are a matrix of 50 cylinders having a length equal to 5 centimeters and a radius of 1 centimeter, the peak conduction current would then be 50 x 2 1r (1 cm)(5 cm)(0.007 A/cm ) = 11 A.
0~ course, it shoul-l be understood that the peak current at the beginning of the pulse is greater than this average current due to displacement current and transient sheath effects.
The average conduction current is (11 A) x (30 microseconds)/(4.2 milliseconds~ = 80 mA, and the average power is 100 XV x 80 mA = 8 kW.
The total implantation time for the foregoing example would thus be equal to: (4 x 105 pulses) (4.23 35 milliseconds) = 1692 seconds = 28.2 minutes.
The square array of 50 targets (actually, a 7 by 7 array or 49 targets) would occupy a square 160 centimeters on a side, or an area of 2.6 square meters.
8~ `
From the foregoing example, it may be seen that the desi.red geometrical packing between multiple targets or between a single target and the walls of t'ne enclosure determines the pulse length, whereas the total 5 implantation time is determined by the time T between pulses which is constrained by the ability to cool the target during implantation.
Using the conditions of the above example, the relationship of the chosen pulse length to the required 10 cell spacing and vacuum chamber area is illustrated below in Table 1.
Area of Vacuum Chamber Pulse Length Cell Spacing 2D Base for a 7 x 7 Array 15 ( ~ sec) (cm) of Tools ~m2) _________________ ________ _____________ __________________ 1013 0.8 2018 1.6 3023 2.6 205033 5.3 10058 16.5 From the data above, it seen that the chamber area increases rapidly and nonlinearly as the pulse length increases, increasing roughly as the square of the pulse 25 length.
Again using the conditions from the foregoing example, the effect of changes in the plasma density, keeping other factors constant, is illustrated below in Table 2.
~ 2 density .~ r ~ /r Initial Sheath D o o oRadius (cm~3) (cm) (cm) _ 109 0.03330 60.0 10.0 101 0.010100 5.0 4.0 1011 0.0033300 0.6 2.0 (continued below) ~2~080 Area of a Sheath Radius Fluence Off-time Cell Spacing 7x7 Array at t=30 sec per T 2D o~ tools (cm) pulse (msec)(cm) ~m2) .
518.0 3.2xlOll 1.0 36 6.5 11.5 1.3x1012 4.2 23 2.6 9.5 9.0~1012 29.0 19 1.8 It is seen that with cylindrical targets there is an advantage to increasing the plasma density as much as possible. In addition to the more favorable size scaling noted above, higher plasma density will provide more uni~orm implantation i~ the target has less than per~ct cylindrical symmetry.
Implantation may also 15 be accomplished with planar targets. Assuming a relatively large planar target in which loading effects are not significant, it may be shown that the maximum pulse length is determined only by the dimension of the vacuum chamber in the direction normal to the target 20 plane. The normalized planar sheath thic~nes~ may be calculated as:
d - rS0/ ~D = (2po) /
so that the initial sheath position is:
rsO e (2~o)l/2 ~D= (2~o)l/ x 743 (Te/n) /
For T = 2 eVj and ~0 = 100 kV, this gives rsO =
3.3 x 10 x (n) Typical values for the various parameters as a function of the plasma density n are given in Table 3 below.
` ~2900~30 Final Sheath Thickness for Various Pulse Length~
n (cm~3) rSO(cm) lO~sec 30~sec 50~sec lOO~sec 109 10.513.0 18.0 23.0 35.5 3 3 5.8 10.8 15.8 28.3 loll 1.1 3.6 8.6 13.6 26.1 The fluence per pulse is F = nrS. Table 4 helow illustrates the scaliny of fluence with pulse length for a density n = 10 per cubic centimeter:
_ Pulse Length Fluence per pulse sec)~(cm~2) 0.6 x loll 1.0 x loll 1.. 6 x loll 100 2.8 x loll For a fixed pulse length of 30 microseconds, the variation o~ fluence with density is shown in Table 5 below:
~29~
Density Fluence per pulse (Cm~3) (cm-2) .
109 0.2 x 10 101 1. 1 x 10 loll 8.6 x loll It is seen that the fluence per pulse is much lower for planar targets than for cylindrical targets because there is no geometric compression (i.e., the planar sheath area equals the planar target area). The heat transfer limitations thus allow a higher duty cycle for the implantation of planar targets. If a heat transfer limit of 5 watts/cm is assumed, as well as a typical fluence per pulse of 1011 per square centimeter, the time between pulses is 0.3 milliseconds, providing a duty cycle of 10% if the pulse length is 30imicroseconds. It is also seen that for planar targets there is little advantage in increasing the plasma density.
It is understood that the present invention is not limited to the particular embodiments set forth herein as illustrative, but embraces all such modified forms thereof as come within the scope of the following claims.
` ~2900~30 Final Sheath Thickness for Various Pulse Length~
n (cm~3) rSO(cm) lO~sec 30~sec 50~sec lOO~sec 109 10.513.0 18.0 23.0 35.5 3 3 5.8 10.8 15.8 28.3 loll 1.1 3.6 8.6 13.6 26.1 The fluence per pulse is F = nrS. Table 4 helow illustrates the scaliny of fluence with pulse length for a density n = 10 per cubic centimeter:
_ Pulse Length Fluence per pulse sec)~(cm~2) 0.6 x loll 1.0 x loll 1.. 6 x loll 100 2.8 x loll For a fixed pulse length of 30 microseconds, the variation o~ fluence with density is shown in Table 5 below:
~29~
Density Fluence per pulse (Cm~3) (cm-2) .
109 0.2 x 10 101 1. 1 x 10 loll 8.6 x loll It is seen that the fluence per pulse is much lower for planar targets than for cylindrical targets because there is no geometric compression (i.e., the planar sheath area equals the planar target area). The heat transfer limitations thus allow a higher duty cycle for the implantation of planar targets. If a heat transfer limit of 5 watts/cm is assumed, as well as a typical fluence per pulse of 1011 per square centimeter, the time between pulses is 0.3 milliseconds, providing a duty cycle of 10% if the pulse length is 30imicroseconds. It is also seen that for planar targets there is little advantage in increasing the plasma density.
It is understood that the present invention is not limited to the particular embodiments set forth herein as illustrative, but embraces all such modified forms thereof as come within the scope of the following claims.
Claims (37)
1. A method of implanting ions from a plasma into a target object comprising the steps of:
(a) positioning the target object in an enclosing chamber;
(b) generating a plasma of ions which surrounds the target object:
(c) then, independently from generating the plasma, applying a high negative voltage pulse to the target object to accelerate the ions in the plasma toward the target from the plasma surrounding the target at an ion energy sufficient to implant ions impacting the target object beneath the surface of and into the crystal lattice of the target object.
(a) positioning the target object in an enclosing chamber;
(b) generating a plasma of ions which surrounds the target object:
(c) then, independently from generating the plasma, applying a high negative voltage pulse to the target object to accelerate the ions in the plasma toward the target from the plasma surrounding the target at an ion energy sufficient to implant ions impacting the target object beneath the surface of and into the crystal lattice of the target object.
2. The method of Claim 1 wherein the step of accelerating ions toward the target object is performed multiple times in a periodic manner composed of short pulses of ions driven toward the target.
3. The method of Claim 1 wherein the ions are accelerated toward the target at an average energy of at least 20 keV.
4. The method of Claim 1 wherein the plasma contains ionized gases selected from the group consisting of nitrogen, hydrogen, oxygen, and argon.
5. The method of Claim 1 wherein the target object is a metal, the plasma is formed of ionized nitrogen, and the step of accelerating the ions toward the target object is performed to provide an average energy to the nitrogen ions of at least 40 keV.
6. The method of Claim 1 wherein the target object is formed of silicon.
7. The method of Claim 1 wherein the ions are accelerated to impact the target object at an energy sufficient to drive ions on an average at least several hundred Angstroms beneath the surface of the target object.
8. The method of Claim 1 wherein the material forming the target object is selected from the group consisting of pure metals, metal alloys, semiconductors, ceramics, and organic polymers.
9. The method of Claim 2 wherein the ions are accelerated toward the target in pulses of a duration of at least approximately 1 microsecond at a repetition rate of at least approximately 60 times per second.
10. A method of implanting ions in a target object comprising the steps of:
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a target object within the chamber spaced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) independently of forming the plasma, applying a pulse of high voltage between the chamber walls and the target object at a voltage sufficient to implant ions from the plasma into the target object.
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a target object within the chamber spaced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) independently of forming the plasma, applying a pulse of high voltage between the chamber walls and the target object at a voltage sufficient to implant ions from the plasma into the target object.
11. The method of Claim 10 wherein the step of applying a pulse of voltage between the chamber walls and the target object is performed repetitively and periodically until a desired concentration of ions in the target object has been obtained.
12. The method of Claim 10 wherein, in the step of applying a pulse of voltage, the voltage is at least 20 kilovolts.
13. The method of Claim 10 wherein the material of the target object is selected from the group consisting of pure metals, alloys, semiconductors, ceramics and organic polymers.
14. The method of Claim 10 wherein the plasma is formed from ions of gases selected from the group consisting of nitrogen, hydrogen, oxygen and argon.
15. The method of Claim 10 wherein the step of applying a pulse of voltage is performed at a voltage level sufficient to drive ions beneath the surfaces of the target object at least an average of several hundred Angstroms.
16. The method of Claim 10 wherein the step of forming a plasma of ions in the chamber includes the steps of introducing a neutral gas at a controlled rate into the chamber such that a desired low pressure is maintained in the chamber and applying ionizing radiation to the interior of the chamber to ionize the neutral gas in the chamber into a plasma.
17. The method of Claim 16 wherein the step of applying ionizing radiation is performed by ejecting electrons from an electron source into the chamber in a diffuse beam to ionize the neutral atoms or molecules in the chamber.
18. The method of Claim 10 wherein the plasma is formed of ionized nitrogen and the target object is selected from the group consisting of metals, metal alloys, semiconductors, ceramics, and organic polymers.
19. The method of Claim 18 wherein the step of applying a pulse of voltage is performed at a voltage level of at least 20 kilovolts.
20. A method of implanting ions in a target object comprising the steps of:
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a target object within the chamber spaced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) applying repetitive pulses of high voltage between the chamber walls and the target object independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target object, the width of the pulses being selected such that the plasma sheath surrounding the target object does not expand to contact the enclosure walls during the pulse.
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a target object within the chamber spaced away from the walls of the chamber;
(c) evacuating the interior of the chamber to a very low base pressure;
(d) forming a plasma of ions in the chamber around the target object;
(e) applying repetitive pulses of high voltage between the chamber walls and the target object independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target object, the width of the pulses being selected such that the plasma sheath surrounding the target object does not expand to contact the enclosure walls during the pulse.
21. The method of Claim 20 wherein, in the steps of applying repetitive pulses of voltage, the voltage is at least 20 kilovolts.
22. The method of Claim 20 wherein the step of forming a plasma of ions in the chamber includes the steps of introducing a neutral gas at a controlled rate into the chamber such that a desired low pressure is maintained in the chamber and applying ionizing radiation to the interior of the chamber to ionize the neutral gas in the chamber into a plasma.
23. The method of Claim 22 wherein the step of applying ionizing radiation is performed by ejecting electrons from an electron source into the chamber in a diffuse beam to ionize the neutral atoms or molecules in the chamber.
24. The method of Claim 20 wherein in the step of applying repetitive pulses of voltage, the time between pulses is selected such that thermal equilibrium of the target object is maintained.
25. A method of implanting ions in a target object comprising the steps of:
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a plurality of target objects within the chamber spaced away from the walls of the chamber and from each other;
(c) evacuating the interior of the chamber to a very lot, base pressure;
(d) forming a plasma of ions in the chamber around the target objects:
(e) applying repetitive pulses of high voltage between the chamber walls and the target objects independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target objects, the width of each pulse of high voltage selected such that the plasma sheath surrounding each target object does not expand during the pulse to contact the plasma sheath surrounding another target object or to contact the walls of the chamber.
(a) providing an enclosing chamber having walls of electrically conductive material;
(b) suspending a plurality of target objects within the chamber spaced away from the walls of the chamber and from each other;
(c) evacuating the interior of the chamber to a very lot, base pressure;
(d) forming a plasma of ions in the chamber around the target objects:
(e) applying repetitive pulses of high voltage between the chamber walls and the target objects independently of the forming of the plasma to draw ions in the plasma to the target object at a voltage sufficient to implant ions from the plasma into the target objects, the width of each pulse of high voltage selected such that the plasma sheath surrounding each target object does not expand during the pulse to contact the plasma sheath surrounding another target object or to contact the walls of the chamber.
26. The method of Claim 25 wherein, in the step of applying repetitive pulses of voltage, the voltage is at least 20 kilovolts.
27. The method of Claim 25 wherein the step of forming a plasma of ions in the chamber includes the steps of introducing a neutral gas at a controlled rate into the chamber such that a desired low pressure is maintained in the chamber and applying ionizing radiation to the interior of the chamber to ionize the neutral gas in the chamber into a plasma.
28. The method of Claim 27 wherein the step of applying ionizing radiation is performed by ejecting electrons from an electron source into the chamber in a diffuse beam to ionize the neutral atoms or molecules in the chamber.
29. The method of Claim 25 wherein in the step of applying repetitive pulses of high voltage, the time spacing between pulses is selected such that thermal equilibrium of the target objects is maintained.
30. An apparatus for implanting ions in a target object comprising:
(a) electrically conductive enclosure walls defining an enclosing chamber surrounding a sealed space;
(b) means for supporting a target object within the enclosing chamber at a position spaced away from and electrically isolated from the enclosure walls of the chamber and for providing an electrical connection between the target object so supported and the exterior of the chamber;
(c) means for forming a plasma of ions of a selected material within the enclosing chamber around the target object;
(d) means for evacuating the interior of the enclosing chamber to a desired low pressure level; and (e) means, independent of the means for forming a plasma, for applying a pulse of voltage between the enclosure walls and the target object sufficient to implant ions from the plasma into the target object.
(a) electrically conductive enclosure walls defining an enclosing chamber surrounding a sealed space;
(b) means for supporting a target object within the enclosing chamber at a position spaced away from and electrically isolated from the enclosure walls of the chamber and for providing an electrical connection between the target object so supported and the exterior of the chamber;
(c) means for forming a plasma of ions of a selected material within the enclosing chamber around the target object;
(d) means for evacuating the interior of the enclosing chamber to a desired low pressure level; and (e) means, independent of the means for forming a plasma, for applying a pulse of voltage between the enclosure walls and the target object sufficient to implant ions from the plasma into the target object.
31. The apparatus of Claim 30 wherein the means for applying a pulse of voltage applies pulses repetitively and periodically at a peak voltage level of not less than 20 kilovolts.
32. The apparatus of Claim 30 wherein the means for supporting the target object within the enclosing chamber includes a stage adapted to hold a target object and be in electrical contact therewith, and a conductive support arm extending from the conductive stage and through the conductive walls of the chamber, the conductive arm being sealed to and electrically insulated from the enclosure wall through which it extends.
33. The apparatus of Claim 30 wherein the means for forming a plasma of ions includes means for supplying a selected plasma source neutral gas at a controlled rate into the interior of the enclosing chamber such that a desired low pressure level is maintained within the chamber and means for applying ionizing radiation to the neutral gas in the chamber to ionize the gas into a plasma.
34. The apparatus of Claim 33 wherein the means for applying ionizing radiation to the neutral gas includes an electron beam source mounted to the chamber wall to inject a diffuse beam of electrons into the interior of the enclosing chamber wherein the electrons make contact with and ionize neutral atoms or molecules of the gas within the chamber.
35. The apparatus of Claim 34 including magnets mounted on the walls of the enclosing chamber to provide a magnetic field extending into the chamber to deflect electrons ejected into the interior of the chamber away from the walls to thereby maximize the path length of the electrons within the chamber and the likelihood of collision between electrons and neutral atoms within the chamber.
36. The apparatus of Claim 34 wherein the means for applying a high voltage pulse between the enclosure walls and the target object includes a high voltage pulse source connected to the means for supporting the target object within the chamber and means for grounding the conductive enclosure walls of the chamber.
37. The apparatus of Claim 30 wherein the means for supporting a target object supports a plurality of target objects at positions in the enclosing chamber spaced away from the enclosure walls and from each other.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US005,457 | 1987-01-20 | ||
| US07/005,457 US4764394A (en) | 1987-01-20 | 1987-01-20 | Method and apparatus for plasma source ion implantation |
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| Publication Number | Publication Date |
|---|---|
| CA1290080C true CA1290080C (en) | 1991-10-01 |
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ID=21715974
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000556845A Expired - Lifetime CA1290080C (en) | 1987-01-20 | 1988-01-19 | Method and apparatus for plasma source ion implantation |
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| US (1) | US4764394A (en) |
| CA (1) | CA1290080C (en) |
Families Citing this family (181)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR930003857B1 (en) * | 1987-08-05 | 1993-05-14 | 마쯔시다덴기산교 가부시기가이샤 | Plasma doping method |
| FR2631832B1 (en) * | 1988-05-24 | 1994-05-27 | Unirec | METHOD FOR REDUCING THE COEFFICIENT OF FRICTION AND WEAR BETWEEN A METAL PIECE AND A PIECE BASED ON AN ORGANIC POLYMER OR COPOLYMER AND ITS APPLICATION TO JOINT PROSTHESES |
| US5013578A (en) * | 1989-12-11 | 1991-05-07 | University Of California | Apparatus for coating a surface with a metal utilizing a plasma source |
| US5378146A (en) * | 1990-02-07 | 1995-01-03 | Ormco Corporation | Polyurethane biomedical devices & method of making same |
| US5126163A (en) * | 1990-09-05 | 1992-06-30 | Northeastern University | Method for metal ion implantation using multiple pulsed arcs |
| KR930011413B1 (en) | 1990-09-25 | 1993-12-06 | 가부시키가이샤 한도오따이 에네루기 겐큐쇼 | Plasma cvd method for using pulsed waveform |
| US5296272A (en) * | 1990-10-10 | 1994-03-22 | Hughes Aircraft Company | Method of implanting ions from a plasma into an object |
| CA2052080C (en) * | 1990-10-10 | 1997-01-14 | Jesse N. Matossian | Plasma source arrangement for ion implantation |
| US5212425A (en) * | 1990-10-10 | 1993-05-18 | Hughes Aircraft Company | Ion implantation and surface processing method and apparatus |
| US5218179A (en) * | 1990-10-10 | 1993-06-08 | Hughes Aircraft Company | Plasma source arrangement for ion implantation |
| US5075130A (en) * | 1990-11-19 | 1991-12-24 | The United States Of America As Represented By The Secretary Of The Army | Surface modification of boron carbide to form pockets of solid lubricant |
| US5143747A (en) | 1991-02-12 | 1992-09-01 | Hughes Aircraft Company | Die improved tooling for metal working |
| EP0502634B1 (en) * | 1991-03-07 | 1997-04-09 | Minnesota Mining And Manufacturing Company | A polymer with crosslinked surface zones |
| US5389195A (en) * | 1991-03-07 | 1995-02-14 | Minnesota Mining And Manufacturing Company | Surface modification by accelerated plasma or ions |
| FR2681472B1 (en) | 1991-09-18 | 1993-10-29 | Commissariat Energie Atomique | PROCESS FOR PRODUCING THIN FILMS OF SEMICONDUCTOR MATERIAL. |
| US5272015A (en) * | 1991-12-19 | 1993-12-21 | General Motors Corporation | Wear resistant hyper-eutectic aluminum-silicon alloys having surface implanted wear resistant particles |
| US5244375A (en) * | 1991-12-19 | 1993-09-14 | Formica Technology, Inc. | Plasma ion nitrided stainless steel press plates and applications for same |
| CA2097388A1 (en) * | 1992-07-16 | 1994-01-17 | Susan Nord Bohlke | Topographical selective patterns |
| US5330800A (en) * | 1992-11-04 | 1994-07-19 | Hughes Aircraft Company | High impedance plasma ion implantation method and apparatus |
| US5289010A (en) * | 1992-12-08 | 1994-02-22 | Wisconsin Alumni Research Foundation | Ion purification for plasma ion implantation |
| US5375451A (en) * | 1992-12-16 | 1994-12-27 | Wisconsin Alumni Research Foundation | Testing system for dissipative mechanical phenomena |
| US5374456A (en) | 1992-12-23 | 1994-12-20 | Hughes Aircraft Company | Surface potential control in plasma processing of materials |
| US5572038A (en) * | 1993-05-07 | 1996-11-05 | Varian Associates, Inc. | Charge monitor for high potential pulse current dose measurement apparatus and method |
| US5354381A (en) * | 1993-05-07 | 1994-10-11 | Varian Associates, Inc. | Plasma immersion ion implantation (PI3) apparatus |
| US5498290A (en) * | 1993-08-27 | 1996-03-12 | Hughes Aircraft Company | Confinement of secondary electrons in plasma ion processing |
| CA2130167C (en) * | 1993-08-27 | 1999-07-20 | Jesse N. Matossian | Nondestructive determination of plasma processing treatment |
| US5473165A (en) * | 1993-11-16 | 1995-12-05 | Stinnett; Regan W. | Method and apparatus for altering material |
| US5532495A (en) * | 1993-11-16 | 1996-07-02 | Sandia Corporation | Methods and apparatus for altering material using ion beams |
| US5558718A (en) * | 1994-04-08 | 1996-09-24 | The Regents, University Of California | Pulsed source ion implantation apparatus and method |
| US5449920A (en) * | 1994-04-20 | 1995-09-12 | Northeastern University | Large area ion implantation process and apparatus |
| US5883016A (en) * | 1994-06-08 | 1999-03-16 | Northeastern University | Apparatus and method for hydrogenating polysilicon thin film transistors by plasma immersion ion implantation |
| US5508227A (en) * | 1994-06-08 | 1996-04-16 | Northeastern University | Plasma ion implantation hydrogenation process utilizing voltage pulse applied to substrate |
| US5661043A (en) * | 1994-07-25 | 1997-08-26 | Rissman; Paul | Forming a buried insulator layer using plasma source ion implantation |
| US6342191B1 (en) | 1994-12-07 | 2002-01-29 | Apyron Technologies, Inc. | Anchored catalyst system and method of making and using thereof |
| US5948726A (en) * | 1994-12-07 | 1999-09-07 | Project Earth Industries, Inc. | Adsorbent and/or catalyst and binder system and method of making therefor |
| US5985790A (en) * | 1994-12-07 | 1999-11-16 | Project Earth Industries, Inc. | Method of making acid contacted enhanced aluminum oxide adsorbent particle |
| IL116877A (en) * | 1995-01-23 | 2000-07-26 | Sandia Corp | Polymer surface treatment with pulse particle beams |
| US5458927A (en) * | 1995-03-08 | 1995-10-17 | General Motors Corporation | Process for the formation of wear- and scuff-resistant carbon coatings |
| WO1996031899A1 (en) * | 1995-04-07 | 1996-10-10 | Advanced Energy Industries, Inc. | Adjustable energy quantum thin film plasma processing system |
| US5955393A (en) * | 1995-04-21 | 1999-09-21 | Project Earth Industries, Inc. | Enhanced adsorbent and room temperature catalyst particle and method of making therefor |
| US5672541A (en) * | 1995-06-14 | 1997-09-30 | Wisconsin Alumni Research Foundation | Ultra-shallow junction semiconductor device fabrication |
| US5693376A (en) * | 1995-06-23 | 1997-12-02 | Wisconsin Alumni Research Foundation | Method for plasma source ion implantation and deposition for cylindrical surfaces |
| US5554854A (en) * | 1995-07-17 | 1996-09-10 | Eaton Corporation | In situ removal of contaminants from the interior surfaces of an ion beam implanter |
| US5633506A (en) * | 1995-07-17 | 1997-05-27 | Eaton Corporation | Method and apparatus for in situ removal of contaminants from ion beam neutralization and implantation apparatuses |
| US5653811A (en) | 1995-07-19 | 1997-08-05 | Chan; Chung | System for the plasma treatment of large area substrates |
| US5712000A (en) * | 1995-10-12 | 1998-01-27 | Hughes Aircraft Company | Large-scale, low pressure plasma-ion deposition of diamondlike carbon films |
| US5859404A (en) * | 1995-10-12 | 1999-01-12 | Hughes Electronics Corporation | Method and apparatus for plasma processing a workpiece in an enveloping plasma |
| FR2748851B1 (en) | 1996-05-15 | 1998-08-07 | Commissariat Energie Atomique | PROCESS FOR PRODUCING A THIN FILM OF SEMICONDUCTOR MATERIAL |
| US5734544A (en) * | 1996-07-09 | 1998-03-31 | Megapulse, Inc. | Solid-state pulse generating apparatus and method particularly adapted for ion implantation |
| US5654043A (en) * | 1996-10-10 | 1997-08-05 | Eaton Corporation | Pulsed plate plasma implantation system and method |
| US5911832A (en) * | 1996-10-10 | 1999-06-15 | Eaton Corporation | Plasma immersion implantation with pulsed anode |
| US6098655A (en) * | 1996-12-03 | 2000-08-08 | Carolina Power & Light Company | Alleviating sticking of normally closed valves in nuclear reactor plants |
| JP4013271B2 (en) * | 1997-01-16 | 2007-11-28 | 日新電機株式会社 | Article surface treatment method and apparatus |
| US6291313B1 (en) | 1997-05-12 | 2001-09-18 | Silicon Genesis Corporation | Method and device for controlled cleaving process |
| US20070122997A1 (en) | 1998-02-19 | 2007-05-31 | Silicon Genesis Corporation | Controlled process and resulting device |
| US6033974A (en) | 1997-05-12 | 2000-03-07 | Silicon Genesis Corporation | Method for controlled cleaving process |
| US5994207A (en) | 1997-05-12 | 1999-11-30 | Silicon Genesis Corporation | Controlled cleavage process using pressurized fluid |
| US6027988A (en) * | 1997-05-28 | 2000-02-22 | The Regents Of The University Of California | Method of separating films from bulk substrates by plasma immersion ion implantation |
| JP3042450B2 (en) * | 1997-06-24 | 2000-05-15 | 日本電気株式会社 | Plasma processing method |
| US6548382B1 (en) | 1997-07-18 | 2003-04-15 | Silicon Genesis Corporation | Gettering technique for wafers made using a controlled cleaving process |
| US6572933B1 (en) | 1997-09-24 | 2003-06-03 | The Regents Of The University Of California | Forming adherent coatings using plasma processing |
| DE19750909C1 (en) | 1997-11-17 | 1999-04-15 | Bosch Gmbh Robert | Rotating unit for plasma immersion aided treatment of substrates |
| US6544406B1 (en) * | 1997-12-08 | 2003-04-08 | Harvest Energy Technology Inc. | Ion implantation of antifoulants for reducing coke deposits |
| FR2773261B1 (en) | 1997-12-30 | 2000-01-28 | Commissariat Energie Atomique | METHOD FOR THE TRANSFER OF A THIN FILM COMPRISING A STEP OF CREATING INCLUSIONS |
| EP1046186B1 (en) * | 1998-01-09 | 2002-12-18 | E.I. Du Pont De Nemours And Company | Plasma treatment for producing electron emitters |
| US5858849A (en) * | 1998-01-15 | 1999-01-12 | United Microelectronics Corp. | Method of manufacturing self-aligned silicide |
| US6120660A (en) * | 1998-02-11 | 2000-09-19 | Silicon Genesis Corporation | Removable liner design for plasma immersion ion implantation |
| US6274459B1 (en) | 1998-02-17 | 2001-08-14 | Silicon Genesis Corporation | Method for non mass selected ion implant profile control |
| US6143631A (en) | 1998-05-04 | 2000-11-07 | Micron Technology, Inc. | Method for controlling the morphology of deposited silicon on a silicon dioxide substrate and semiconductor devices incorporating such deposited silicon |
| US6101971A (en) * | 1998-05-13 | 2000-08-15 | Axcelis Technologies, Inc. | Ion implantation control using charge collection, optical emission spectroscopy and mass analysis |
| US6291326B1 (en) | 1998-06-23 | 2001-09-18 | Silicon Genesis Corporation | Pre-semiconductor process implant and post-process film separation |
| US6300643B1 (en) | 1998-08-03 | 2001-10-09 | Varian Semiconductor Equipment Associates, Inc. | Dose monitor for plasma doping system |
| US6676595B1 (en) | 1998-08-24 | 2004-01-13 | Varian Medical Systems Technologies, Inc. | Radioactive medical implant and method of manufacturing |
| US6050218A (en) * | 1998-09-28 | 2000-04-18 | Eaton Corporation | Dosimetry cup charge collection in plasma immersion ion implantation |
| US6224536B1 (en) * | 1999-02-08 | 2001-05-01 | Advanced Cardiovascular Systems | Method for delivering radiation therapy to an intravascular site in a body |
| CN1275790A (en) * | 1999-05-27 | 2000-12-06 | 索尼株式会社 | Surface treatment method and equipment |
| JP4682387B2 (en) | 1999-05-31 | 2011-05-11 | ソニー株式会社 | Insulator surface treatment method |
| US6458723B1 (en) | 1999-06-24 | 2002-10-01 | Silicon Genesis Corporation | High temperature implant apparatus |
| JP2003506883A (en) | 1999-08-10 | 2003-02-18 | シリコン ジェネシス コーポレイション | Cleavage process for manufacturing multi-layer substrates with low implant dose |
| US6500732B1 (en) | 1999-08-10 | 2002-12-31 | Silicon Genesis Corporation | Cleaving process to fabricate multilayered substrates using low implantation doses |
| US6263941B1 (en) | 1999-08-10 | 2001-07-24 | Silicon Genesis Corporation | Nozzle for cleaving substrates |
| US6221740B1 (en) | 1999-08-10 | 2001-04-24 | Silicon Genesis Corporation | Substrate cleaving tool and method |
| US6383273B1 (en) | 1999-08-12 | 2002-05-07 | Apyron Technologies, Incorporated | Compositions containing a biocidal compound or an adsorbent and/or catalyst compound and methods of making and using therefor |
| US6504159B1 (en) | 1999-09-14 | 2003-01-07 | International Business Machines Corporation | SOI plasma source ion implantation |
| US6182604B1 (en) | 1999-10-27 | 2001-02-06 | Varian Semiconductor Equipment Associates, Inc. | Hollow cathode for plasma doping system |
| US6335536B1 (en) | 1999-10-27 | 2002-01-01 | Varian Semiconductor Equipment Associates, Inc. | Method and apparatus for low voltage plasma doping using dual pulses |
| US6433553B1 (en) | 1999-10-27 | 2002-08-13 | Varian Semiconductor Equipment Associates, Inc. | Method and apparatus for eliminating displacement current from current measurements in a plasma processing system |
| US6458430B1 (en) | 1999-12-22 | 2002-10-01 | Axcelis Technologies, Inc. | Pretreatment process for plasma immersion ion implantation |
| US20010044027A1 (en) | 1999-12-30 | 2001-11-22 | Anderson Jerrel Charles | Diamond-like carbon coating on glass for added hardness and abrasion resistance |
| US20040028906A1 (en) * | 2000-01-04 | 2004-02-12 | Anderson Jerrel Charles | Diamond-like carbon coating on glass and plastic for added hardness and abrasion resistance |
| US6939434B2 (en) | 2000-08-11 | 2005-09-06 | Applied Materials, Inc. | Externally excited torroidal plasma source with magnetic control of ion distribution |
| US7166524B2 (en) * | 2000-08-11 | 2007-01-23 | Applied Materials, Inc. | Method for ion implanting insulator material to reduce dielectric constant |
| US7294563B2 (en) * | 2000-08-10 | 2007-11-13 | Applied Materials, Inc. | Semiconductor on insulator vertical transistor fabrication and doping process |
| US7223676B2 (en) | 2002-06-05 | 2007-05-29 | Applied Materials, Inc. | Very low temperature CVD process with independently variable conformality, stress and composition of the CVD layer |
| US6893907B2 (en) | 2002-06-05 | 2005-05-17 | Applied Materials, Inc. | Fabrication of silicon-on-insulator structure using plasma immersion ion implantation |
| US7037813B2 (en) * | 2000-08-11 | 2006-05-02 | Applied Materials, Inc. | Plasma immersion ion implantation process using a capacitively coupled plasma source having low dissociation and low minimum plasma voltage |
| US7094316B1 (en) | 2000-08-11 | 2006-08-22 | Applied Materials, Inc. | Externally excited torroidal plasma source |
| US7183177B2 (en) * | 2000-08-11 | 2007-02-27 | Applied Materials, Inc. | Silicon-on-insulator wafer transfer method using surface activation plasma immersion ion implantation for wafer-to-wafer adhesion enhancement |
| US7320734B2 (en) * | 2000-08-11 | 2008-01-22 | Applied Materials, Inc. | Plasma immersion ion implantation system including a plasma source having low dissociation and low minimum plasma voltage |
| US7479456B2 (en) | 2004-08-26 | 2009-01-20 | Applied Materials, Inc. | Gasless high voltage high contact force wafer contact-cooling electrostatic chuck |
| US7288491B2 (en) * | 2000-08-11 | 2007-10-30 | Applied Materials, Inc. | Plasma immersion ion implantation process |
| US7430984B2 (en) * | 2000-08-11 | 2008-10-07 | Applied Materials, Inc. | Method to drive spatially separate resonant structure with spatially distinct plasma secondaries using a single generator and switching elements |
| US7094670B2 (en) | 2000-08-11 | 2006-08-22 | Applied Materials, Inc. | Plasma immersion ion implantation process |
| US7465478B2 (en) * | 2000-08-11 | 2008-12-16 | Applied Materials, Inc. | Plasma immersion ion implantation process |
| US7303982B2 (en) * | 2000-08-11 | 2007-12-04 | Applied Materials, Inc. | Plasma immersion ion implantation process using an inductively coupled plasma source having low dissociation and low minimum plasma voltage |
| US7137354B2 (en) * | 2000-08-11 | 2006-11-21 | Applied Materials, Inc. | Plasma immersion ion implantation apparatus including a plasma source having low dissociation and low minimum plasma voltage |
| US7309997B1 (en) | 2000-09-15 | 2007-12-18 | Varian Semiconductor Equipment Associates, Inc. | Monitor system and method for semiconductor processes |
| DE60206084T2 (en) * | 2001-02-06 | 2006-01-12 | Shibuya Kogyo Co., Ltd., Kanazawa | Method and apparatus for modifying the inner surface of plastic containers |
| TW580730B (en) * | 2001-03-09 | 2004-03-21 | Macronix Int Co Ltd | Method of forming a silicon oxide layer with different thickness using pulsed nitrogen plasma implantation |
| FR2823599B1 (en) | 2001-04-13 | 2004-12-17 | Commissariat Energie Atomique | DEMOMTABLE SUBSTRATE WITH CONTROLLED MECHANICAL HOLDING AND METHOD OF MAKING |
| US7163901B2 (en) | 2002-03-13 | 2007-01-16 | Varian Semiconductor Equipment Associates, Inc. | Methods for forming thin film layers by simultaneous doping and sintering |
| AU2003223376A1 (en) * | 2002-03-28 | 2003-10-13 | Scimed Life Systems, Inc. | Polymer welding using ferromagnetic particles |
| US6979420B2 (en) * | 2002-03-28 | 2005-12-27 | Scimed Life Systems, Inc. | Method of molding balloon catheters employing microwave energy |
| US7163655B2 (en) * | 2002-03-28 | 2007-01-16 | Scimed Life Systems, Inc. | Method and apparatus for extruding polymers employing microwave energy |
| US6878415B2 (en) * | 2002-04-15 | 2005-04-12 | Varian Semiconductor Equipment Associates, Inc. | Methods for chemical formation of thin film layers using short-time thermal processes |
| US6758949B2 (en) * | 2002-09-10 | 2004-07-06 | Applied Materials, Inc. | Magnetically confined metal plasma sputter source with magnetic control of ion and neutral densities |
| US8187377B2 (en) | 2002-10-04 | 2012-05-29 | Silicon Genesis Corporation | Non-contact etch annealing of strained layers |
| FR2848336B1 (en) | 2002-12-09 | 2005-10-28 | Commissariat Energie Atomique | METHOD FOR PRODUCING A STRESS STRUCTURE FOR DISSOCIATING |
| EP2351869A1 (en) * | 2002-12-20 | 2011-08-03 | COPPE/UFRJ - Coordenação dos Programas de Pós Graduação de Engenharia da Universidade Federal do Rio de Janeiro | Hydrogen diffusion barrier on steel by means of a pulsed-plasma ion-nitriding process |
| US6803070B2 (en) | 2002-12-30 | 2004-10-12 | Scimed Life Systems, Inc. | Apparatus and method for embedding nanoparticles in polymeric medical devices |
| US8862203B2 (en) * | 2003-03-27 | 2014-10-14 | Boston Scientific Scimed Inc. | Medical device with temperature modulator for use in magnetic resonance imaging |
| FR2856844B1 (en) | 2003-06-24 | 2006-02-17 | Commissariat Energie Atomique | HIGH PERFORMANCE CHIP INTEGRATED CIRCUIT |
| FR2857953B1 (en) | 2003-07-21 | 2006-01-13 | Commissariat Energie Atomique | STACKED STRUCTURE, AND METHOD FOR MANUFACTURING THE SAME |
| US20050061251A1 (en) * | 2003-09-02 | 2005-03-24 | Ronghua Wei | Apparatus and method for metal plasma immersion ion implantation and metal plasma immersion ion deposition |
| FR2861497B1 (en) | 2003-10-28 | 2006-02-10 | Soitec Silicon On Insulator | METHOD FOR CATASTROPHIC TRANSFER OF A FINE LAYER AFTER CO-IMPLANTATION |
| WO2005042064A1 (en) * | 2003-10-31 | 2005-05-12 | Ventracor Limited | Improved blood pump comprising polymeric components |
| US7695590B2 (en) | 2004-03-26 | 2010-04-13 | Applied Materials, Inc. | Chemical vapor deposition plasma reactor having plural ion shower grids |
| US20050211547A1 (en) * | 2004-03-26 | 2005-09-29 | Applied Materials, Inc. | Reactive sputter deposition plasma reactor and process using plural ion shower grids |
| US7291360B2 (en) | 2004-03-26 | 2007-11-06 | Applied Materials, Inc. | Chemical vapor deposition plasma process using plural ion shower grids |
| US7244474B2 (en) | 2004-03-26 | 2007-07-17 | Applied Materials, Inc. | Chemical vapor deposition plasma process using an ion shower grid |
| US20050260354A1 (en) * | 2004-05-20 | 2005-11-24 | Varian Semiconductor Equipment Associates, Inc. | In-situ process chamber preparation methods for plasma ion implantation systems |
| US20050287307A1 (en) * | 2004-06-23 | 2005-12-29 | Varian Semiconductor Equipment Associates, Inc. | Etch and deposition control for plasma implantation |
| US7767561B2 (en) | 2004-07-20 | 2010-08-03 | Applied Materials, Inc. | Plasma immersion ion implantation reactor having an ion shower grid |
| US8058156B2 (en) | 2004-07-20 | 2011-11-15 | Applied Materials, Inc. | Plasma immersion ion implantation reactor having multiple ion shower grids |
| US20060040065A1 (en) * | 2004-08-19 | 2006-02-23 | Han-Chang Shih | Method for the surface activation on the metalization of electronic devices |
| US20060043531A1 (en) * | 2004-08-27 | 2006-03-02 | Varian Semiconductor Equipment Associates, Inc. | Reduction of source and drain parasitic capacitance in CMOS devices |
| US7666464B2 (en) * | 2004-10-23 | 2010-02-23 | Applied Materials, Inc. | RF measurement feedback control and diagnostics for a plasma immersion ion implantation reactor |
| CN1322163C (en) * | 2004-11-05 | 2007-06-20 | 哈尔滨工业大学 | Plasma injection method and apparatus for insulation material spare parts |
| TWI268558B (en) * | 2005-02-23 | 2006-12-11 | Univ Chung Yuan Christian | Ion implantation system and method of monitoring implanting voltage of ion implantation device |
| US7428915B2 (en) * | 2005-04-26 | 2008-09-30 | Applied Materials, Inc. | O-ringless tandem throttle valve for a plasma reactor chamber |
| US20060260545A1 (en) * | 2005-05-17 | 2006-11-23 | Kartik Ramaswamy | Low temperature absorption layer deposition and high speed optical annealing system |
| US7109098B1 (en) | 2005-05-17 | 2006-09-19 | Applied Materials, Inc. | Semiconductor junction formation process including low temperature plasma deposition of an optical absorption layer and high speed optical annealing |
| US7312162B2 (en) * | 2005-05-17 | 2007-12-25 | Applied Materials, Inc. | Low temperature plasma deposition process for carbon layer deposition |
| US7422775B2 (en) * | 2005-05-17 | 2008-09-09 | Applied Materials, Inc. | Process for low temperature plasma deposition of an optical absorption layer and high speed optical annealing |
| US20080311686A1 (en) * | 2005-08-03 | 2008-12-18 | California Institute Of Technology | Method of Forming Semiconductor Layers on Handle Substrates |
| US7323401B2 (en) * | 2005-08-08 | 2008-01-29 | Applied Materials, Inc. | Semiconductor substrate process using a low temperature deposited carbon-containing hard mask |
| US7429532B2 (en) * | 2005-08-08 | 2008-09-30 | Applied Materials, Inc. | Semiconductor substrate process using an optically writable carbon-containing mask |
| US7312148B2 (en) * | 2005-08-08 | 2007-12-25 | Applied Materials, Inc. | Copper barrier reflow process employing high speed optical annealing |
| US7335611B2 (en) * | 2005-08-08 | 2008-02-26 | Applied Materials, Inc. | Copper conductor annealing process employing high speed optical annealing with a low temperature-deposited optical absorber layer |
| FR2889887B1 (en) | 2005-08-16 | 2007-11-09 | Commissariat Energie Atomique | METHOD FOR DEFERING A THIN LAYER ON A SUPPORT |
| FR2891281B1 (en) | 2005-09-28 | 2007-12-28 | Commissariat Energie Atomique | METHOD FOR MANUFACTURING A THIN FILM ELEMENT |
| DE102006003386A1 (en) * | 2006-01-24 | 2007-07-26 | Reichel, Walter, Dipl.-Ing. | Ion implantation unit for roller surfaces, comprises an ion source, an accelerator, a vacuum chamber and a deflection unit |
| US8993410B2 (en) | 2006-09-08 | 2015-03-31 | Silicon Genesis Corporation | Substrate cleaving under controlled stress conditions |
| US9362439B2 (en) | 2008-05-07 | 2016-06-07 | Silicon Genesis Corporation | Layer transfer of films utilizing controlled shear region |
| US7811900B2 (en) | 2006-09-08 | 2010-10-12 | Silicon Genesis Corporation | Method and structure for fabricating solar cells using a thick layer transfer process |
| US8293619B2 (en) | 2008-08-28 | 2012-10-23 | Silicon Genesis Corporation | Layer transfer of films utilizing controlled propagation |
| FR2910179B1 (en) | 2006-12-19 | 2009-03-13 | Commissariat Energie Atomique | METHOD FOR MANUFACTURING THIN LAYERS OF GaN BY IMPLANTATION AND RECYCLING OF A STARTING SUBSTRATE |
| KR100841083B1 (en) | 2006-12-28 | 2008-06-25 | 한국원자력연구원 | A surface treatment method for reactor structure materials |
| KR20090106617A (en) * | 2007-01-19 | 2009-10-09 | 어플라이드 머티어리얼스, 인코포레이티드 | Plasma immersion chamber |
| US8029875B2 (en) * | 2007-05-23 | 2011-10-04 | Southwest Research Institute | Plasma immersion ion processing for coating of hollow substrates |
| FR2925221B1 (en) | 2007-12-17 | 2010-02-19 | Commissariat Energie Atomique | METHOD FOR TRANSFERRING A THIN LAYER |
| US9175381B2 (en) * | 2008-07-09 | 2015-11-03 | Southwest Research Institute | Processing tubular surfaces using double glow discharge |
| US8330126B2 (en) | 2008-08-25 | 2012-12-11 | Silicon Genesis Corporation | Race track configuration and method for wafering silicon solar substrates |
| US8268081B2 (en) * | 2008-10-02 | 2012-09-18 | Varian Semiconductor Equipment Associates, Inc. | Platen cleaning method |
| US8329557B2 (en) | 2009-05-13 | 2012-12-11 | Silicon Genesis Corporation | Techniques for forming thin films by implantation with reduced channeling |
| FR2947098A1 (en) | 2009-06-18 | 2010-12-24 | Commissariat Energie Atomique | METHOD OF TRANSFERRING A THIN LAYER TO A TARGET SUBSTRATE HAVING A THERMAL EXPANSION COEFFICIENT DIFFERENT FROM THAT OF THE THIN LAYER |
| US20100326271A1 (en) * | 2009-06-25 | 2010-12-30 | Omax Corporation | Reciprocating pump and method for making a system with enhanced dynamic seal reliability |
| US20120000606A1 (en) * | 2010-07-02 | 2012-01-05 | Varian Semiconductor Equipment Associates, Inc. | Plasma uniformity system and method |
| US8361856B2 (en) | 2010-11-01 | 2013-01-29 | Micron Technology, Inc. | Memory cells, arrays of memory cells, and methods of forming memory cells |
| US8329567B2 (en) | 2010-11-03 | 2012-12-11 | Micron Technology, Inc. | Methods of forming doped regions in semiconductor substrates |
| US8450175B2 (en) | 2011-02-22 | 2013-05-28 | Micron Technology, Inc. | Methods of forming a vertical transistor and at least a conductive line electrically coupled therewith |
| US8753725B2 (en) | 2011-03-11 | 2014-06-17 | Southwest Research Institute | Method for plasma immersion ion processing and depositing coatings in hollow substrates using a heated center electrode |
| US8569831B2 (en) | 2011-05-27 | 2013-10-29 | Micron Technology, Inc. | Integrated circuit arrays and semiconductor constructions |
| US9036391B2 (en) | 2012-03-06 | 2015-05-19 | Micron Technology, Inc. | Arrays of vertically-oriented transistors, memory arrays including vertically-oriented transistors, and memory cells |
| US9129896B2 (en) | 2012-08-21 | 2015-09-08 | Micron Technology, Inc. | Arrays comprising vertically-oriented transistors, integrated circuitry comprising a conductive line buried in silicon-comprising semiconductor material, methods of forming a plurality of conductive lines buried in silicon-comprising semiconductor material, and methods of forming an array comprising vertically-oriented transistors |
| US9006060B2 (en) | 2012-08-21 | 2015-04-14 | Micron Technology, Inc. | N-type field effect transistors, arrays comprising N-type vertically-oriented transistors, methods of forming an N-type field effect transistor, and methods of forming an array comprising vertically-oriented N-type transistors |
| US9478550B2 (en) | 2012-08-27 | 2016-10-25 | Micron Technology, Inc. | Arrays of vertically-oriented transistors, and memory arrays including vertically-oriented transistors |
| US9121540B2 (en) | 2012-11-21 | 2015-09-01 | Southwest Research Institute | Superhydrophobic compositions and coating process for the internal surface of tubular structures |
| US9111853B2 (en) | 2013-03-15 | 2015-08-18 | Micron Technology, Inc. | Methods of forming doped elements of semiconductor device structures |
| US10808688B1 (en) | 2017-07-03 | 2020-10-20 | Omax Corporation | High pressure pumps having a check valve keeper and associated systems and methods |
| WO2021202390A1 (en) | 2020-03-30 | 2021-10-07 | Hypertherm, Inc. | Cylinder for a liquid jet pump with multi-functional interfacing longitudinal ends |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3117022A (en) * | 1960-09-06 | 1964-01-07 | Space Technhology Lab Inc | Deposition arrangement |
| US3900636A (en) * | 1971-01-21 | 1975-08-19 | Gillette Co | Method of treating cutting edges |
| US3806380A (en) * | 1971-03-05 | 1974-04-23 | Hitachi Ltd | Method for hardening treatment of aluminum or aluminum-base alloy |
| GB1392811A (en) * | 1971-04-07 | 1975-04-30 | Atomic Energy Authority Uk | Methods for treating steel to modify the structure thereof |
| US3915757A (en) * | 1972-08-09 | 1975-10-28 | Niels N Engel | Ion plating method and product therefrom |
| US3913520A (en) * | 1972-08-14 | 1975-10-21 | Precision Thin Film Corp | High vacuum deposition apparatus |
| US4170662A (en) * | 1974-11-05 | 1979-10-09 | Eastman Kodak Company | Plasma plating |
| US4039416A (en) * | 1975-04-21 | 1977-08-02 | White Gerald W | Gasless ion plating |
| GB1542299A (en) * | 1976-03-23 | 1979-03-14 | Warner Lambert Co | Blade shields |
| CH640886A5 (en) * | 1979-08-02 | 1984-01-31 | Balzers Hochvakuum | METHOD FOR APPLYING HARD WEAR-RESISTANT COATS ON DOCKS. |
| US4342631A (en) * | 1980-06-16 | 1982-08-03 | Illinois Tool Works Inc. | Gasless ion plating process and apparatus |
| US4471003A (en) * | 1980-11-25 | 1984-09-11 | Cann Gordon L | Magnetoplasmadynamic apparatus and process for the separation and deposition of materials |
| FR2501727A1 (en) * | 1981-03-13 | 1982-09-17 | Vide Traitement | PROCESS FOR THE THERMOCHEMICAL TREATMENT OF METALS BY ION BOMBING |
| US4486247A (en) * | 1982-06-21 | 1984-12-04 | Westinghouse Electric Corp. | Wear resistant steel articles with carbon, oxygen and nitrogen implanted in the surface thereof |
| US4500563A (en) * | 1982-12-15 | 1985-02-19 | Pacific Western Systems, Inc. | Independently variably controlled pulsed R.F. plasma chemical vapor processing |
| US4468309A (en) * | 1983-04-22 | 1984-08-28 | White Engineering Corporation | Method for resisting galling |
| GB2144343A (en) * | 1983-08-02 | 1985-03-06 | Standard Telephones Cables Ltd | Optical fibre manufacture |
| GB2155024A (en) * | 1984-03-03 | 1985-09-18 | Standard Telephones Cables Ltd | Surface treatment of plastics materials |
-
1987
- 1987-01-20 US US07/005,457 patent/US4764394A/en not_active Expired - Lifetime
-
1988
- 1988-01-19 CA CA000556845A patent/CA1290080C/en not_active Expired - Lifetime
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| US4764394A (en) | 1988-08-16 |
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