WO2001093320A1 - Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode - Google Patents

Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode Download PDF

Info

Publication number
WO2001093320A1
WO2001093320A1 PCT/KR2000/000573 KR0000573W WO0193320A1 WO 2001093320 A1 WO2001093320 A1 WO 2001093320A1 KR 0000573 W KR0000573 W KR 0000573W WO 0193320 A1 WO0193320 A1 WO 0193320A1
Authority
WO
WIPO (PCT)
Prior art keywords
thin film
substrate
ion beam
tin
semiconductor
Prior art date
Application number
PCT/KR2000/000573
Other languages
French (fr)
Inventor
Seok-Keun Koh
Jung Cho
Original Assignee
Korea Institute Of Science And Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Korea Institute Of Science And Technology filed Critical Korea Institute Of Science And Technology
Priority to KR10-2002-7001202A priority Critical patent/KR100451415B1/en
Priority to PCT/KR2000/000573 priority patent/WO2001093320A1/en
Publication of WO2001093320A1 publication Critical patent/WO2001093320A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/76853—Barrier, adhesion or liner layers characterized by particular after-treatment steps
    • H01L21/76855—After-treatment introducing at least one additional element into the layer
    • H01L21/76856—After-treatment introducing at least one additional element into the layer by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
    • H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
    • H01L21/285—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation
    • H01L21/28506—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers
    • H01L21/28512—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System
    • H01L21/28568—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System the conductive layers comprising transition metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/76853—Barrier, adhesion or liner layers characterized by particular after-treatment steps
    • H01L21/76855—After-treatment introducing at least one additional element into the layer
    • H01L21/76859—After-treatment introducing at least one additional element into the layer by ion implantation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/76853—Barrier, adhesion or liner layers characterized by particular after-treatment steps
    • H01L21/76861—Post-treatment or after-treatment not introducing additional chemical elements into the layer
    • H01L21/76862—Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/76853—Barrier, adhesion or liner layers characterized by particular after-treatment steps
    • H01L21/76861—Post-treatment or after-treatment not introducing additional chemical elements into the layer
    • H01L21/76864—Thermal treatment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/10—Applying interconnections to be used for carrying current between separate components within a device
    • H01L2221/1068—Formation and after-treatment of conductors
    • H01L2221/1073—Barrier, adhesion or liner layers
    • H01L2221/1078—Multiple stacked thin films not being formed in openings in dielectrics

Definitions

  • the present invention relates to a platinum electrode structure for a semiconductor and a method for enhancing adhesion between a semiconductor substrate and a platinum substrate, and in particular to a technique of forming a TiN/Ti gradient buffer layer, by modifying a surface using an ion beam assisted method, in order to enhance adhesion of Pt deposited on a silicon wafer or glass substrate.
  • the properties and fabrication methods of the materials constituting the device as well as the design of the device are very important.
  • a thermal and electrical stability are required between a substrate and an oxide film, and between the electrodes in order to employ an advanced technique of forming various electric components on a single substrate.
  • Al has been generally used as an electrode material.
  • Pt is utilized as an electrode material for smart materials, such as a Micro Electro Mechanical System (MEMS) which has been recently widely used.
  • MEMS Micro Electro Mechanical System
  • Pt has a high thermal and chemical stability properties. Especially, Pt does not oxidize well.
  • the adhesion between the Pt and wafer of film is too low, and thus Pt easily falls off. That is, when the thin film is deposited on the silicon wafer and heat is applied thereto, the thin film and the substrate cannot easily adhere because of the difference in the thermal expansion of coefficient and crystallographic growth orientation.
  • TiN is used as a buffer thin film.
  • the TiN thin film has a columnar structure, and is grown on the silicon wafer.
  • Ti existing between the substrate and the electrode acts as a diffusion path for the substrate or electrode.
  • titanium oxide is formed between the surface and the grain boundary.
  • a conventional surface modification method employs energy of a few hundreds keV. Therefore, a device for generating an ion beam is very large in size, and peripheral devices are complicated. As a result, the method is difficult to be normally used.
  • the surface is damaged by the high energy particles. For example, when the surface is varied to a high energy state, the mechanical property and the chemical resistance to hydrochloric acid are deteriorated due to the structural variation at a high temperature.
  • a Pt electrode structure for a semiconductor including: a semiconductor substrate; a TiN/Ti gradient layer formed at an upper portion of the substrate; and a Pt thin film formed at an upper portion of the gradient layer.
  • a silicon or glass may be used as the substrate material.
  • the TiN/Ti gradient layer may be formed on an insulation film formed on the silicon wafer.
  • a method for enhancing the adhesion between a semiconductor substrate and a platinum electrode including: a step for depositing a Ti seed layer on the semiconductor substrate; a step for forming a TiN/Ti gradient layer by irradiating nitrogen ion beam and injecting reaction gas to the surface of the Ti seed layer; and a step for depositing a Pt thin film on the TiN/Ti gradient layer.
  • the injection amount of the ion beam is preferably 1 x 10 15 ⁇ 1 x 10 17 ions/cm 2 .
  • An acceleration voltage is about 1 keV.
  • Nitrogen is used as the reaction gas.
  • An injection amount of the nitrogen gas is advantageously between 0.1 and 6ml/min.
  • a degree of vacuum is preferably 1.5 x 10 " torr.
  • the nitride (TiN gradient layer) formed on the TiN thin film operates as a buffer layer, thereby enhancing the adhesion of Pt and thermal stability. Accordingly, the nitride operates as a diffusion barrier layer at an Ti interface, thereby reducing stress.
  • the substrate is stable to temperature increases, and maintains adhesion. Accordingly, the electric conductivity can be improved by applying the present invention to form an electrode for a semiconductor or fabricating an ultra thin film device of electric electronic materials.
  • Figure 1 a illustrates a TiN/Ti gradient layer on a Ti surface, when nitrogen ion beam was irradiated to the Ti surface
  • Figure 1b illustrates a microstructure of a TiN/Ti gradient layer
  • Figure 2 shows a surface modification apparatus used for the present invention
  • Figure 3 is a graph showing variation of surface roughness according to variation of the ion amount of irradiation, after modifying the Ti surface by nitrogen ion beam assisted reaction;
  • Figure 4A to 4D are an AFM image showing the surface roughness of Figure 3 in a three-dimensional shape
  • Figure 5 is a graph showing variation of the surface roughness according to variation of an injection amount of nitrogen gas which was the reaction gas, when the ion irradiation amount was 1 x 10 16 ions/cm 2 , an ion beam current density was 1 ⁇ A/cm 2 , and an ion beam energy was 1 keV;
  • Figure 6 is a photograph showing the Scotch tape test results of a sample processed according to the nitrogen ion beam assisted reaction method, and a sample which was not;
  • Figure 7 is a photograph showing the Scotch tape test results of the sample processed according to the nitrogen ion beam assisted reaction method, and the sample which was not;
  • Figure 8 is a graph showing variation of the adhesion of the sample which was processed by the nitrogen ion beam assisted reaction method, according to variation of the ion amount of irradiation;
  • Figures 9a to 9d are photographs respectively showing microstructure cross-section, after annealing a sample which was surface-modified according to the present invention, wherein: Figure 9a is a photograph in a state where the sample was annealed for 1 hour at a temperature of 100°C;
  • Figure 9b is a photograph in a state where the sample was annealed for 1 hour at a temperature of 300°C;
  • Figure 9c is a photograph in a state where the sample was annealed for 1 hour at a temperature of 500°C.
  • Figure 9d is a photograph in a state where the sample was annealed for 1 hour at a temperature of 700°C.
  • Figure 10 is a photograph showing an adhesion test result of a surface- modified Ti formed on a glass substrate and Pt formed thereon. MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS
  • a method for modifying a surface of a ceramic or glass by using an ion beam is basically different in the material structure and mechanism from a method for modifying a surface of a polymer by using ion beam.
  • an inorganic material surface such as ceramic and glass maintains a molecular bonding state having a strong adhesion, through covalent bonding and ion bonding, and thus having a solid phase with high surface strength and adhesion. Accordingly, the bonding scission of the surface, a kind of surface damage, modified by the ion beam are relatively less generated, as compared with the polymer.
  • a strain is varied by stress of the surface or the surface becomes amorphous. That is, a crystal structure and a chemical composition are varied.
  • the surface is varied to a different surface structure to AIN.
  • the surface stress is varied, thereby forming a different aluminum compound layer.
  • the adhesion with Al and Cu is remarkably enhanced. The increase of the adhesion is closely connected with the formation of the hydrophilic group.
  • Figure 1 a is a diagram illustrating a step for forming a TiN/Ti gradient layer on a surface of a Ti thin film 2 formed on a substrate 1 , by irradiating nitrogen ions 3 having energy of 1 keV and injecting nitrogen gas 4.
  • a lattice spacing of a conventional titanium metal thin film was increased due to the gradient TiN resulting from the injection of the nitrogen ions 3, thereby increasing the atom density.
  • Reference numeral 5 denotes the Ti lattice spacing in the TiN layer
  • reference numeral 6 denotes the Ti lattice spacing in the Ti layer.
  • FIG. 2 is a schematic diagram illustrating a surface modification apparatus for modifying the surface of a Ti thin film 13 by using the nitrogen ion beam.
  • the surface atoms of the Ti thin film 13 are activated by the collision with the nitrogen ions of energy of 1keV accelerated by an ion gun 11 from an ion source 10, the Ti thin film 13 reacts with the reaction gas, thereby forming bonds of TiN or TiON.
  • a vacuum pump 14 is provided at one side of the apparatus.
  • a Ti seed layer was formed on a silicon wafer or glass substrate, and a Ti thin film was deposited thereon. Ion was irradiated to the Ti thin film according to a nitrogen ion beam assisted reaction method.
  • the deposition conditions were as follows. A vacuum degree in a chamber was maintained approximately at 3 x 10 " 5 Torr. Thereafter, an ion beam energy of 1 keV was irradiated to the titanium thin film, injecting the nitrogen ions of 2ml/min to a cold cathode ion gun at an operational pressure of 1.2x10 "4 Torr. A deposition speed was approximately 0.1 A/sec, and the deposited titanium thin film was approximately 200A. The thusly-formed titanium thin film was positioned at an upper portion in the chamber. Nitrogen ion beam was irradiated to the thin film, and the nitrogen ions were injected around the thin film, thereby forming a TiN/Ti gradient layer.
  • FIG. 3 is a graph showing variation of the surface roughness of the sample according to variation of the amount of ion irradiation. As compared with other sputtering methods, the surface roughness of the thin film formed by using the ion beam was remarkably low. As shown in the graph, when the sample is not surface-modified at an initial stage, the roughness is 0.26A. When the irradiation amount was increased according to the ion beam assisted reaction method, the roughness of the thin film was constant. However, when the ion beam was irradiated at 1 x 10 17 ions/cm 2 , the roughness sharply increased.
  • Figure 4 is a picture showing variation of the surface roughness according to the amount of ion irradiation of Figure 3 in a three-dimensional shape.
  • Figure 4A is a sample which is not processed
  • Figure 4B is a sample which was processed with the nitrogen ions at the ion irradiation amount of 1 x 10 15 ions/cm 2
  • Figure 4C is a sample which was processed with the nitrogen ions at the ion irradiation amount of 1 x 10 16 ions/cm 2
  • Figure 4D is a sample which was processed with the nitrogen ions at the ion irradiation amount of 1 x 10 17 ions/cm 2 , respectively.
  • Example 2
  • the surface roughness was observed by maintaining the ion irradiation amount of 1 x 10 6 ions/cm 2 , irradiating the ion beam at an acceleration energy of 1 keV, and varying the amount of nitrogen gas to be injected around the sample.
  • Figure 5 is a graph showing the variation of the surface roughness according to variation of the injection amount of the nitrogen gas.
  • the surface becomes softer according to the increase of the amount of the nitrogen gas.
  • the value of the surface roughness increased.
  • Figure 6 is a photograph showing the results of a Scotch tape test performed after depositing the platinum thin film on the TiN/Ti gradient film formed by modifying the Ti surface under the conditions of argon injecting at 2ml/min, the acceleration energy of 1 keV and the nitrogen gas injection amount of 6ml/min.
  • the substrate was not wholly surface- processed, the titanium thin film was deposited on the substrate, and the platinum thin film was deposited thereon. There was no adhesion between the platinum thin film and the titanium thin film. Accordingly, the platinum thin film fell off.
  • the titanium thin film was deposited according to the Argon ion beam sputtering method.
  • Figure 7 is a photograph showing the result of the adhesion test performed by varying the amount of ion irradiation.
  • the condition was (a) 1 x 10 15 ions/cm 2 , (b) 5 x 10 15 ions/cm 2 , and (c) 1 x 10 16 lons/cm 2 .
  • the left side of the samples indicate a portion to which the platinum was adhered, and the right sides thereof indicate a portion which was not processed.
  • the platinum thin film wholly fell off from the right sides.
  • sample (c) showed very good adhesion.
  • Figure 8 is a graph showing the result of the scratch test according to variation of the amount of ion irradiation.
  • a rectangular diamond tip having a diameter of 2mm was employed. The tip was moved in a different direction, and the load was consecutively increased.
  • the adhesion was also enhanced. The adhesion had maximal value at 5 x 10 16 ions/cm 2 . However, when the amount of ion irradiation exceeded 5 x 10 16 ions/cm 2 , the adhesion did not increase.
  • FIG. 9a is a photograph in a state where the sample was annealed for 1 hour at a temperature of 100°C
  • Figure 9b is a photograph in a state where the sample was annealed for 1 hour at a temperature of 300°C.
  • Figure 9c is a photograph in a state where the sample was annealed for 1 hour at a temperature of 500°C
  • Figure 9d is a photograph in a state where the sample was annealed for 1 hour at a temperature of 700°C.
  • the temperature increased, diffusion was generated between the substrate and the thin film. Accordingly, a thermal spike or a hillock phenomenon took place at an interface thereof. However, such phenomena did not happen at the interface of the thin film according to the present invention, even when the temperature rose.
  • a titanium thin film was deposited on a glass substrate, and then the surface thereof was modified by employing a nitrogen ion beam.
  • the platinum thin film was deposited thereon.
  • Figure 10 shows the test result.
  • the adhesion test of the present example after the Scotch tape test, the sample which was not processed and the processed sample were placed in a beaker. Water is poured into the beaker. Thereafter, the water was boiled at a temperature of approximately 120°C for about 6 hours. The samples were tested again with Scotch tape.
  • the adhesion of the Pt electrode deposited on the semiconductor substrate is enhanced, and the influence of the interface resulting from the increase of the temperature is reduced.
  • the oxidation of the Ti thin film which is the intermediate layer is prevented, and the thermal diffusion of the platinum is prevented between the substrate and the Ti thin film.
  • the present invention modifies merely the surface of the Ti thin film by using the nitrogen, and thus can be applied to almost all semiconductor process.
  • the surface is modified with a relatively low energy of a few keV, and thus the energy size of the ion beam is actually not limited.
  • the device can be remarkably simplified.
  • the adhesion between the substrate and the platinum electrode can be enhanced without damaging the surface, and the surface can be stably modified at a high temperature.

Abstract

The present invention relates to a platinum electrode structure for a semiconductor, having: a semiconductor substrate; a TiN/Ti gradient layer formed at an upper portion of the substrate; and a Pt thin film formed at an upper portion of the gradient layer. In addition, the present invention relates to a method for enhancing adhesion between a semiconductor substrate and a platinum electrode, by: depositing a Ti seed layer on the semiconductor substrate; forming a TiN/Ti gradient layer by irradiating nitrogen ion beam and injecting reaction gas to the surface of the Ti seed layer; and depositing a Pt thin film on the TiN/Ti gradient layer.

Description

PLATINUM ELECTRODE STRUCTURE FOR SEMICONDUCTOR AND METHOD FOR ENHANCING ADHESION BETWEEN SEMICONDUCTOR SUBSTRATE AND PLATINUM ELECTRODE
TECHNICAL FIELD
The present invention relates to a platinum electrode structure for a semiconductor and a method for enhancing adhesion between a semiconductor substrate and a platinum substrate, and in particular to a technique of forming a TiN/Ti gradient buffer layer, by modifying a surface using an ion beam assisted method, in order to enhance adhesion of Pt deposited on a silicon wafer or glass substrate.
BACKGROUND ART
To achieve a high integration for a semiconductor device, the properties and fabrication methods of the materials constituting the device as well as the design of the device are very important. Especially, in a non-memory device or logic device, a thermal and electrical stability are required between a substrate and an oxide film, and between the electrodes in order to employ an advanced technique of forming various electric components on a single substrate. In the conventional art, Al has been generally used as an electrode material.
On the other hand, Pt is utilized as an electrode material for smart materials, such as a Micro Electro Mechanical System (MEMS) which has been recently widely used. Pt has a high thermal and chemical stability properties. Especially, Pt does not oxidize well. However, in the case Pt is deposited on a silicon wafer or silicon oxide film according to the conventional sputtering method, the adhesion between the Pt and wafer of film is too low, and thus Pt easily falls off. That is, when the thin film is deposited on the silicon wafer and heat is applied thereto, the thin film and the substrate cannot easily adhere because of the difference in the thermal expansion of coefficient and crystallographic growth orientation.
Accordingly, in order to improve the adhesion, TiN is used as a buffer thin film. The TiN thin film has a columnar structure, and is grown on the silicon wafer. However, as the temperature rises, Ti existing between the substrate and the electrode acts as a diffusion path for the substrate or electrode. In addition, when the TiN film is exposed to air, titanium oxide is formed between the surface and the grain boundary. On the other hand, a conventional surface modification method employs energy of a few hundreds keV. Therefore, a device for generating an ion beam is very large in size, and peripheral devices are complicated. As a result, the method is difficult to be normally used. Also, even if the modification is performed, the surface is damaged by the high energy particles. For example, when the surface is varied to a high energy state, the mechanical property and the chemical resistance to hydrochloric acid are deteriorated due to the structural variation at a high temperature.
DISCLOSURE OF THE INVENTION Therefore, it is an object of the present invention to enhance the adhesion of a Pt thin film by depositing Ti on a semiconductor substrate and modifying the surface of Ti with ion beam of low energy (a few keV), thereby to restrict the influence of an interface resulting from temperature increases.
It is another object of the present invention to fabricate an intermediate layer having superior adhesion properties, minimizing the generation of a Ti oxide film, and avoiding a thermal diffusion of Pt between a substrate and a Ti thin film.
In order to achieve the above-described objects of the present invention, there is provided a Pt electrode structure for a semiconductor including: a semiconductor substrate; a TiN/Ti gradient layer formed at an upper portion of the substrate; and a Pt thin film formed at an upper portion of the gradient layer. A silicon or glass may be used as the substrate material. The TiN/Ti gradient layer may be formed on an insulation film formed on the silicon wafer. In addition, there is provided a method for enhancing the adhesion between a semiconductor substrate and a platinum electrode, including: a step for depositing a Ti seed layer on the semiconductor substrate; a step for forming a TiN/Ti gradient layer by irradiating nitrogen ion beam and injecting reaction gas to the surface of the Ti seed layer; and a step for depositing a Pt thin film on the TiN/Ti gradient layer. The injection amount of the ion beam is preferably 1 x 1015~ 1 x 1017ions/cm2. An acceleration voltage is about 1 keV. Nitrogen is used as the reaction gas. An injection amount of the nitrogen gas is advantageously between 0.1 and 6ml/min.
In addition, a degree of vacuum is preferably 1.5 x 10" torr.
The nitride (TiN gradient layer) formed on the TiN thin film operates as a buffer layer, thereby enhancing the adhesion of Pt and thermal stability. Accordingly, the nitride operates as a diffusion barrier layer at an Ti interface, thereby reducing stress. When an influence of an interface between the thin films is observed after annealing the substrate on which the Pt thin film fabricated according to the present invention is deposited, the substrate is stable to temperature increases, and maintains adhesion. Accordingly, the electric conductivity can be improved by applying the present invention to form an electrode for a semiconductor or fabricating an ultra thin film device of electric electronic materials.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 a illustrates a TiN/Ti gradient layer on a Ti surface, when nitrogen ion beam was irradiated to the Ti surface, and Figure 1b illustrates a microstructure of a TiN/Ti gradient layer;
Figure 2 shows a surface modification apparatus used for the present invention;
Figure 3 is a graph showing variation of surface roughness according to variation of the ion amount of irradiation, after modifying the Ti surface by nitrogen ion beam assisted reaction;
Figure 4A to 4D are an AFM image showing the surface roughness of Figure 3 in a three-dimensional shape;
Figure 5 is a graph showing variation of the surface roughness according to variation of an injection amount of nitrogen gas which was the reaction gas, when the ion irradiation amount was 1 x 1016ions/cm2, an ion beam current density was 1 μA/cm2, and an ion beam energy was 1 keV;
Figure 6 is a photograph showing the Scotch tape test results of a sample processed according to the nitrogen ion beam assisted reaction method, and a sample which was not;
Figure 7 is a photograph showing the Scotch tape test results of the sample processed according to the nitrogen ion beam assisted reaction method, and the sample which was not;
Figure 8 is a graph showing variation of the adhesion of the sample which was processed by the nitrogen ion beam assisted reaction method, according to variation of the ion amount of irradiation;
Figures 9a to 9d are photographs respectively showing microstructure cross-section, after annealing a sample which was surface-modified according to the present invention, wherein: Figure 9a is a photograph in a state where the sample was annealed for 1 hour at a temperature of 100°C;
Figure 9b is a photograph in a state where the sample was annealed for 1 hour at a temperature of 300°C;
Figure 9c is a photograph in a state where the sample was annealed for 1 hour at a temperature of 500°C; and
Figure 9d is a photograph in a state where the sample was annealed for 1 hour at a temperature of 700°C; and
Figure 10 is a photograph showing an adhesion test result of a surface- modified Ti formed on a glass substrate and Pt formed thereon. MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS
A method for modifying a surface of a ceramic or glass by using an ion beam is basically different in the material structure and mechanism from a method for modifying a surface of a polymer by using ion beam.
In the polymer surface modification using the ion beam, a chain scission is generated at polymer chains by an interaction between the polymer and the ion beam having an energy. Thereafter, a cross linkage phenomenon that the chains are bonded to each other takes place. Oxygen gas is injected, and thus the surface having the unstable chains reacts therewith, thereby forming new polymer groups according to a series of chemical reactions. This phenomenon occurs on the most of polymer surfaces.
Conversely, as compared with the polymer, an inorganic material surface such as ceramic and glass maintains a molecular bonding state having a strong adhesion, through covalent bonding and ion bonding, and thus having a solid phase with high surface strength and adhesion. Accordingly, the bonding scission of the surface, a kind of surface damage, modified by the ion beam are relatively less generated, as compared with the polymer. In general, when particles having a low energy are irradiated to a surface of the inorganic material, especially a metal or ceramic, a strain is varied by stress of the surface or the surface becomes amorphous. That is, a crystal structure and a chemical composition are varied. For example, when the ion beam is irradiated to the surface of AIN, and oxygen is injected thereto at the same time, the surface is varied to a different surface structure to AIN. In addition, the surface stress is varied, thereby forming a different aluminum compound layer.
In the polymer surface modification, in order to improve the hydrophilicity, there is provided a method for increasing the surface energy by removing foreign materials by irradiating the ion beam of a few kV and cleaning the surface, or by increasing roughness of the surface, and a method for forming a hydrophilic group, such as -C=0 and -COOH on the surface by a chemical reaction with the unstable polymer chains or free radicals, in the case that the oxygen is simultaneously injected, as described above. In the case of the polymer modified according to the latter method, the adhesion with Al and Cu is remarkably enhanced. The increase of the adhesion is closely connected with the formation of the hydrophilic group. in this regard, a portion which is not bonded to atoms such as metal and oxygen, namely dangling bonds exist on ceramic surface. As a result, the ceramic surface shows a different surface electronic structure to a bulk, namely a stress/strain. Accordingly, in the case the ion beam is incident on the ceramic surface, the bonds are cut or unstable. In this state, when the reaction gas is injected, new bonds between the metal and gas or gas and gas are formed at the surface of the ceramic, thereby forming a different compound phase to the suface. The contents and characteristics of the present invention will now be described in detail with reference to the accompanying drawings.
Figure 1 a is a diagram illustrating a step for forming a TiN/Ti gradient layer on a surface of a Ti thin film 2 formed on a substrate 1 , by irradiating nitrogen ions 3 having energy of 1 keV and injecting nitrogen gas 4. According to the surface modification of the thin film, as shown in Figure 1 b, a lattice spacing of a conventional titanium metal thin film was increased due to the gradient TiN resulting from the injection of the nitrogen ions 3, thereby increasing the atom density. Reference numeral 5 denotes the Ti lattice spacing in the TiN layer, and reference numeral 6 denotes the Ti lattice spacing in the Ti layer.
Figure 2 is a schematic diagram illustrating a surface modification apparatus for modifying the surface of a Ti thin film 13 by using the nitrogen ion beam. The surface atoms of the Ti thin film 13 are activated by the collision with the nitrogen ions of energy of 1keV accelerated by an ion gun 11 from an ion source 10, the Ti thin film 13 reacts with the reaction gas, thereby forming bonds of TiN or TiON. A vacuum pump 14 is provided at one side of the apparatus.
Example 1
A Ti seed layer was formed on a silicon wafer or glass substrate, and a Ti thin film was deposited thereon. Ion was irradiated to the Ti thin film according to a nitrogen ion beam assisted reaction method. The deposition conditions were as follows. A vacuum degree in a chamber was maintained approximately at 3 x 10" 5Torr. Thereafter, an ion beam energy of 1 keV was irradiated to the titanium thin film, injecting the nitrogen ions of 2ml/min to a cold cathode ion gun at an operational pressure of 1.2x10"4Torr. A deposition speed was approximately 0.1 A/sec, and the deposited titanium thin film was approximately 200A. The thusly-formed titanium thin film was positioned at an upper portion in the chamber. Nitrogen ion beam was irradiated to the thin film, and the nitrogen ions were injected around the thin film, thereby forming a TiN/Ti gradient layer.
The surface roughness of the thusly-formed thin film is an important variable because it considerably influences the adhesion with the thin film deposited thereon. Figure 3 is a graph showing variation of the surface roughness of the sample according to variation of the amount of ion irradiation. As compared with other sputtering methods, the surface roughness of the thin film formed by using the ion beam was remarkably low. As shown in the graph, when the sample is not surface-modified at an initial stage, the roughness is 0.26A. When the irradiation amount was increased according to the ion beam assisted reaction method, the roughness of the thin film was constant. However, when the ion beam was irradiated at 1 x 1017ions/cm2, the roughness sharply increased. As known from the conventional polymer surface modification, it is considered that the energy of the irradiated ion beam exceeds a surface cleaning step, the sputtering phenomenon is directly generated, and thus the surface roughness is increased. It is identical to the value obtained' by theoretically computing a structural shape of the incident energy and the substrate. Figure 4 is a picture showing variation of the surface roughness according to the amount of ion irradiation of Figure 3 in a three-dimensional shape. Figure 4A is a sample which is not processed, Figure 4B is a sample which was processed with the nitrogen ions at the ion irradiation amount of 1 x 1015ions/cm2, Figure 4C is a sample which was processed with the nitrogen ions at the ion irradiation amount of 1 x 1016ions/cm2, and Figure 4D is a sample which was processed with the nitrogen ions at the ion irradiation amount of 1 x 1017ions/cm2, respectively. Example 2
The surface roughness was observed by maintaining the ion irradiation amount of 1 x 10 6ions/cm2, irradiating the ion beam at an acceleration energy of 1 keV, and varying the amount of nitrogen gas to be injected around the sample. Figure 5 is a graph showing the variation of the surface roughness according to variation of the injection amount of the nitrogen gas. Here, the surface becomes softer according to the increase of the amount of the nitrogen gas. However, when the gas was injected over 4ml/min, the value of the surface roughness increased.
Example 3
Figure 6 is a photograph showing the results of a Scotch tape test performed after depositing the platinum thin film on the TiN/Ti gradient film formed by modifying the Ti surface under the conditions of argon injecting at 2ml/min, the acceleration energy of 1 keV and the nitrogen gas injection amount of 6ml/min. In the case of sample (a), the substrate was not wholly surface- processed, the titanium thin film was deposited on the substrate, and the platinum thin film was deposited thereon. There was no adhesion between the platinum thin film and the titanium thin film. Accordingly, the platinum thin film fell off. Conversely, in the case of sample (b), the titanium thin film was deposited according to the Argon ion beam sputtering method. Thereafter, a half of the substrate was coated with the aluminum thin film, and the other half was processed with the ion beam. As a result of the test, the portion which was not processed fell off, identically to sample (a). However, the platinum thin film, the TiN/Ti gradient film and the silicon substrate were firmly adhered at the portion which was processed according to the ion beam assisted reaction method. In a state where the radiated Argon ions collide with the atoms on the surface of the titanium thin film to excite in some degree, the cut ions react with the nitrogen ions, thereby forming the thin film having the superior adhesion.
Example 4
Figure 7 is a photograph showing the result of the adhesion test performed by varying the amount of ion irradiation. The condition was (a) 1 x 1015ions/cm2, (b) 5 x 1015ions/cm2, and (c) 1 x 1016lons/cm2. As shown therein, the left side of the samples indicate a portion to which the platinum was adhered, and the right sides thereof indicate a portion which was not processed. Thus, the platinum thin film wholly fell off from the right sides. Here, in the case of samples (a) and (b), the platinum thin film which was processed according to the ion beam assisted reaction method partially fell off. However, sample (c) showed very good adhesion. Figure 8 is a graph showing the result of the scratch test according to variation of the amount of ion irradiation. A rectangular diamond tip having a diameter of 2mm was employed. The tip was moved in a different direction, and the load was consecutively increased. As shown in the graph, when the amount of ion irradiation of the nitrogen ion beam increased, the adhesion was also enhanced. The adhesion had maximal value at 5 x 1016ions/cm2. However, when the amount of ion irradiation exceeded 5 x 1016ions/cm2, the adhesion did not increase.
Example 5
A sample was processed with nitrogen gas of 4ml/min and the ion beam energy of 1 keV under the conditions of nitrogen ion irradiation amount of 1 x 1016ions/cm2 and ion beam current density of 1 μA/cm2, and annealing, thereby observing a cross-section of a microstructure thereof. Figure 9a is a photograph in a state where the sample was annealed for 1 hour at a temperature of 100°C, Figure 9b is a photograph in a state where the sample was annealed for 1 hour at a temperature of 300°C. Figure 9c is a photograph in a state where the sample was annealed for 1 hour at a temperature of 500°C, and Figure 9d is a photograph in a state where the sample was annealed for 1 hour at a temperature of 700°C. In general, when the temperature increased, diffusion was generated between the substrate and the thin film. Accordingly, a thermal spike or a hillock phenomenon took place at an interface thereof. However, such phenomena did not happen at the interface of the thin film according to the present invention, even when the temperature rose.
Example 6
According to another embodiment of the present invention, a titanium thin film was deposited on a glass substrate, and then the surface thereof was modified by employing a nitrogen ion beam. The platinum thin film was deposited thereon. The adhesion between the titanium and the platinum was tested. Figure 10 shows the test result. According to the adhesion test of the present example, after the Scotch tape test, the sample which was not processed and the processed sample were placed in a beaker. Water is poured into the beaker. Thereafter, the water was boiled at a temperature of approximately 120°C for about 6 hours. The samples were tested again with Scotch tape. As shown in Figure 10, in the case of the sample which was not processed(a), the platinum thin film fell off, and in the case of the sample which was processed according to the nitrogen ion beam assisted reaction method(b), the thin film was adhered. This result implied that the nitrogen ions play an important role of adhering the platinum thin film.
In accordance with the present invention, the adhesion of the Pt electrode deposited on the semiconductor substrate is enhanced, and the influence of the interface resulting from the increase of the temperature is reduced. In addition, the oxidation of the Ti thin film which is the intermediate layer is prevented, and the thermal diffusion of the platinum is prevented between the substrate and the Ti thin film. The present invention modifies merely the surface of the Ti thin film by using the nitrogen, and thus can be applied to almost all semiconductor process. Especially, the surface is modified with a relatively low energy of a few keV, and thus the energy size of the ion beam is actually not limited. Also, the device can be remarkably simplified. Furthermore, the adhesion between the substrate and the platinum electrode can be enhanced without damaging the surface, and the surface can be stably modified at a high temperature.

Claims

1. A platinum electrode structure for a semiconductor, comprising: a semiconductor substrate; a TiN/Ti gradient layer formed at an upper portion of the substrate; and a Pt thin film formed at an upper portion of the gradient layer.
2. The structure according to claim 1 , wherein the substrate is silicon.
3. The structure according to claim 1 , wherein the substrate is glass.
4. A platinum electrode structure for a semiconductor, comprising: a semiconductor substrate; an insulation film formed on the substrate; a TiN/Ti gradient layer formed on the insulation film; and a Pt thin film formed at an upper portion of the gradient layer.
5. A method of enhancing adhesion between a semiconductor substrate and a platinum electrode, comprising: depositing a Ti seed layer on the semiconductor substrate; forming a TiN/Ti gradient layer by irradiating nitrogen ion beam and injecting reaction gas to the surface of the Ti seed layer; and depositing a Pt thin film on the TiN/Ti gradient layer.
6. The method according to claim 1 , wherein an amount of injection of the ion beam is 1 x 101S~ 1 x 1017ions/cm2.
7. The method according to claim 5, wherein an acceleration voltage of the ion beam is 1 keV.
8. The method according to claim 5, wherein the reaction gas is nitrogen.
9. The method according to claim 5, wherein an amount of injection of the nitrogen gas is between 0.1 and 6ml/min.
10. The method according to claim 5, wherein a degree of vacuum is
1.5 x 10"4torr.
PCT/KR2000/000573 2000-06-01 2000-06-01 Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode WO2001093320A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
KR10-2002-7001202A KR100451415B1 (en) 2000-06-01 2000-06-01 Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode
PCT/KR2000/000573 WO2001093320A1 (en) 2000-06-01 2000-06-01 Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/KR2000/000573 WO2001093320A1 (en) 2000-06-01 2000-06-01 Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode

Publications (1)

Publication Number Publication Date
WO2001093320A1 true WO2001093320A1 (en) 2001-12-06

Family

ID=19198221

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2000/000573 WO2001093320A1 (en) 2000-06-01 2000-06-01 Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode

Country Status (2)

Country Link
KR (1) KR100451415B1 (en)
WO (1) WO2001093320A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20060020030A (en) 2004-08-30 2006-03-06 삼성에스디아이 주식회사 Fabricating method of donor device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08248442A (en) * 1995-03-13 1996-09-27 Toshiba Corp Liquid crystal display device
US5561307A (en) * 1992-07-23 1996-10-01 Symetrix Corporation Ferroelectric integrated circuit
JPH0945877A (en) * 1995-07-31 1997-02-14 Matsushita Electron Corp Manufacture of capacitor element

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5561307A (en) * 1992-07-23 1996-10-01 Symetrix Corporation Ferroelectric integrated circuit
JPH08248442A (en) * 1995-03-13 1996-09-27 Toshiba Corp Liquid crystal display device
JPH0945877A (en) * 1995-07-31 1997-02-14 Matsushita Electron Corp Manufacture of capacitor element

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
ENSINGER: "Ion bombardment effects during deposition of nitride and metal films", SURFACE AND COATINGS TECHNOLOGY, vol. 99, no. 3, 1998, ELSEVIER SCIENCE, pages 1 - 13 *

Also Published As

Publication number Publication date
KR20020026555A (en) 2002-04-10
KR100451415B1 (en) 2004-10-07

Similar Documents

Publication Publication Date Title
EP3533081B1 (en) High resistivity silicon-on-insulator substrate having enhanced charge trapping efficiency
US11145538B2 (en) High resistivity silicon-on-insulator structure and method of manufacture thereof
US6399177B1 (en) Deposited thin film void-column network materials
US8563076B2 (en) Substrate structure and method of forming the same
EP3821459B1 (en) Radio frequency silicon on insulator wafer platform with superior performance, stability, and manufacturability
JP7115297B2 (en) Polycrystalline diamond free-standing substrate and its manufacturing method
JP2004511102A (en) The process of revealing crystal defects and / or stress fields at the molecular bonding interface of two solid materials
JP3124508B2 (en) Method for modifying nitride surface and nitride surface modified by the method
WO2001093320A1 (en) Platinum electrode structure for semiconductor and method for enhancing adhesion between semiconductor substrate and platinum electrode
Takagi et al. Surface Activated Wafer Bonding; Principle and Current Status
JP3450818B2 (en) Method for producing aluminum nitride thin film with improved surface and bonding properties
Zhang et al. Pulsed laser deposited lead zirconate titanate thin films for micro actuators
Martin et al. Re-growth of c-axis oriented AlN thin films
JP3449979B2 (en) Manufacturing method of aluminum nitride thin film using plasma treatment
Chao et al. Wafer bonding by Ni-induced crystallization of amorphous silicon
CN113337807A (en) Method for preparing two-dimensional material
Smith et al. Plasma enhanced selective area microcrystalline silicon deposition on hydrogenated amorphous silicon: Surface modification for controlled nucleation
Parlevliet et al. Pulsed PECVD growth of silicon nanowires on various substrates
Kononenko et al. Relationship between the void and hillock formation and the grain growth in thin aluminum films
JP2019091923A (en) Method and apparatus for treating substrate surface
KOPPERSCHMIDT et al. Recent Developments in Adhesion-Enhanced High-Vacuum Bonding By In Situ Plasma Surface Precleaning
Sharif et al. Epitaxial silicon thin films by low temperature aluminum induced crystallization of amorphous silicon
Nyawo et al. Reactive DC sputter deposition and charactersation of AlN thin films
Haynes et al. Ion beam modification of film stress and the effectiveness of thin film encapsulants on GaAs

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CN JP KR US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

WWE Wipo information: entry into national phase

Ref document number: 1020027001202

Country of ref document: KR

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWP Wipo information: published in national office

Ref document number: 1020027001202

Country of ref document: KR

WWE Wipo information: entry into national phase

Ref document number: 10031987

Country of ref document: US

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWG Wipo information: grant in national office

Ref document number: 1020027001202

Country of ref document: KR