WO2017051611A1 - Method for producing silicon carbide epitaxial substrate, method for manufacturing silicon carbide semiconductor device, and apparatus for producing silicon carbide epitaxial substrate - Google Patents

Method for producing silicon carbide epitaxial substrate, method for manufacturing silicon carbide semiconductor device, and apparatus for producing silicon carbide epitaxial substrate Download PDF

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WO2017051611A1
WO2017051611A1 PCT/JP2016/072624 JP2016072624W WO2017051611A1 WO 2017051611 A1 WO2017051611 A1 WO 2017051611A1 JP 2016072624 W JP2016072624 W JP 2016072624W WO 2017051611 A1 WO2017051611 A1 WO 2017051611A1
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gas
silicon carbide
epitaxial substrate
carbide epitaxial
temperature
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PCT/JP2016/072624
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French (fr)
Japanese (ja)
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洋典 伊東
土井　秀之
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住友電気工業株式会社
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Publication of WO2017051611A1 publication Critical patent/WO2017051611A1/en

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    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02367—Substrates
    • H01L21/0237—Materials
    • H01L21/02373—Group 14 semiconducting materials
    • H01L21/02378—Silicon carbide
    • 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
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/42—Silicides
    • 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
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/448—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials
    • C23C16/452—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials by activating reactive gas streams before their introduction into the reaction chamber, e.g. by ionisation or addition of reactive species
    • 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
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
    • 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
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/36—Carbides
    • H—ELECTRICITY
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    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02367—Substrates
    • H01L21/02433—Crystal orientation
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02524—Group 14 semiconducting materials
    • H01L21/02529—Silicon carbide
    • H—ELECTRICITY
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    • 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
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/0262—Reduction or decomposition of gaseous compounds, e.g. CVD
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007—Multistep manufacturing processes
    • H01L29/66053—Multistep manufacturing processes of devices having a semiconductor body comprising crystalline silicon carbide
    • H01L29/66068—Multistep manufacturing processes of devices having a semiconductor body comprising crystalline silicon carbide the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic System
    • H01L29/1608—Silicon carbide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/7801—DMOS transistors, i.e. MISFETs with a channel accommodating body or base region adjoining a drain drift region
    • H01L29/7802—Vertical DMOS transistors, i.e. VDMOS transistors

Definitions

  • the present disclosure relates to a method for manufacturing a silicon carbide epitaxial substrate, a method for manufacturing a silicon carbide semiconductor device, and a device for manufacturing a silicon carbide epitaxial substrate.
  • Patent Document 1 discloses a method of epitaxially growing a silicon carbide layer on a silicon carbide single crystal substrate.
  • the method for manufacturing a silicon carbide epitaxial substrate according to the present disclosure includes the following steps.
  • a silicon carbide single crystal substrate having a diameter of 100 mm or more is disposed in the reaction chamber.
  • a mixed gas is generated by mixing the first gas containing carbon and thermally decomposed, the second gas containing silicon, and the third gas containing nitrogen.
  • a mixed gas is introduced into the reaction chamber. By heating the mixed gas in the reaction chamber, a silicon carbide layer is formed on the silicon carbide single crystal substrate.
  • An apparatus for manufacturing a silicon carbide epitaxial substrate includes a reaction chamber, a first gas supply unit, a second gas supply unit, a third gas supply unit, a first thermal decomposition unit, and a mixing unit. ing.
  • the reaction chamber is configured to heat the silicon carbide single crystal substrate.
  • the first gas supply unit is configured to be able to supply a first gas containing carbon.
  • the second gas supply unit is configured to be able to supply a second gas containing silicon.
  • the third gas supply unit is configured to be able to supply a third gas containing nitrogen.
  • the first thermal decomposition unit is configured to be capable of heating the first gas at the first temperature.
  • the mixing unit is configured to be able to mix the first gas, the second gas, and the third gas.
  • the first gas supply unit, the second gas supply unit, and the third gas supply unit are connected to the mixing unit.
  • the first thermal decomposition unit is between the first gas supply unit and the mixing unit.
  • FIG. 1 is a partial schematic cross-sectional view showing a configuration of a silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment.
  • FIG. 2 is a partial cross-sectional schematic diagram showing the configuration of the first modification of the silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment.
  • FIG. 3 is a partial cross-sectional schematic diagram showing the configuration of the second modification of the silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment.
  • FIG. 4 is a partial cross-sectional schematic diagram showing the configuration of the third modification of the silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment.
  • FIG. 5 is a flowchart schematically showing a method for manufacturing the silicon carbide epitaxial substrate according to the present embodiment.
  • FIG. 6 is a schematic cross-sectional view showing a first step of the method for manufacturing the silicon carbide epitaxial substrate according to the present embodiment.
  • FIG. 7 is a schematic cross-sectional view showing a second step of the method for manufacturing the silicon carbide epitaxial substrate according to the present embodiment.
  • FIG. 8 is a flowchart schematically showing a method for manufacturing the silicon carbide semiconductor device according to the present embodiment.
  • FIG. 9 is a schematic cross-sectional view showing a first step of the method for manufacturing the silicon carbide semiconductor device according to this embodiment.
  • FIG. 10 is a schematic cross-sectional view showing a second step of the method for manufacturing the silicon carbide semiconductor device according to this embodiment.
  • FIG. 11 is a schematic cross-sectional view showing a third step of the method for manufacturing the silicon carbide semiconductor device according to this embodiment.
  • a method for manufacturing silicon carbide epitaxial substrate 100 includes the following steps.
  • silicon carbide single crystal substrate 10 having a diameter of 100 mm or more is arranged.
  • a mixed gas is generated by mixing the first gas containing carbon and thermally decomposed, the second gas containing silicon, and the third gas containing nitrogen.
  • a mixed gas is introduced into the reaction chamber 21.
  • silicon carbide layer 20 is formed on silicon carbide single crystal substrate 10.
  • the silicon carbide layer is formed by epitaxial growth
  • a gas containing carbon, a gas containing silicon, a dopant gas, and a carrier gas are supplied to the reaction chamber.
  • a gas containing carbon is difficult to be decomposed. Therefore, in the reaction chamber, the C / Si ratio of the upstream gas with respect to the silicon carbide single crystal substrate tends to be lower than the C / Si ratio of the downstream gas. As a result, the uniformity of the C / Si ratio on the surface of the silicon carbide single crystal substrate is deteriorated.
  • the nitrogen atom of the dopant is introduced into the silicon carbide crystal by replacing the carbon site of the silicon carbide crystal.
  • the lower the C / Si ratio the easier the nitrogen atoms are taken into the silicon carbide crystal. Therefore, when the uniformity of the C / Si ratio on the surface of the silicon carbide single crystal substrate is deteriorated, the uniformity of the concentration of nitrogen atoms in the silicon carbide layer in the direction parallel to the surface of the silicon carbide single crystal substrate is deteriorated.
  • the inventor can selectively decompose the gas containing carbon in advance in the reaction chamber on the surface of the silicon carbide single crystal substrate before supplying the gas containing carbon to the reaction chamber. It has been found that the uniformity of C / Si can be improved. As a result, the uniformity of the carrier concentration in the silicon carbide layer in the direction parallel to the surface of the silicon carbide single crystal substrate can be improved. In other words, the in-plane uniformity of the carrier concentration of the silicon carbide layer can be improved.
  • the second gas may be in a thermally decomposed state.
  • the third gas may be in a thermally decomposed state.
  • the third gas may be in a thermally decomposed state.
  • the first gas contains C 3 H 8 and the first gas has a temperature of 1200 ° C. or higher and 1600 ° C. or lower. It may be in a state where it is thermally decomposed at.
  • the first gas may contain C 3 H 8 diluted with H 2 .
  • the second gas contains SiH 4 , and the second gas is in a state of being thermally decomposed at a temperature of 400 ° C. or higher and 800 ° C. or lower. Good.
  • the third gas includes at least one of N 2 and NH 3 , and the third gas is heated at a temperature of 600 ° C. or higher and 1000 ° C. or lower. It may be in a disassembled state.
  • the third gas includes at least one of N 2 and NH 3 , and the third gas is heated at a temperature of 600 ° C. or higher and 1000 ° C. or lower. It may be in a disassembled state.
  • the method for manufacturing the silicon carbide semiconductor device 300 according to the present disclosure includes the following steps.
  • a silicon carbide epitaxial substrate 100 manufactured by the method described in any one of (1) to (9) above is prepared. Silicon carbide epitaxial substrate 100 is processed.
  • the silicon carbide epitaxial substrate 100 manufacturing apparatus 200 includes a reaction chamber 21, a first gas supply unit 1, a second gas supply unit 2, a third gas supply unit 3, and a first heating.
  • a decomposition unit 5 and a mixing unit 50 are provided.
  • Reaction chamber 21 is configured to heat silicon carbide single crystal substrate 10.
  • the 1st gas supply part 1 is comprised so that supply of the 1st gas containing carbon is possible.
  • the second gas supply unit 2 is configured to be able to supply a second gas containing silicon.
  • the 3rd gas supply part 3 is comprised so that supply of the 3rd gas containing nitrogen is possible.
  • the first thermal decomposition unit 5 is configured to be able to heat the first gas at the first temperature.
  • the mixing unit 50 is configured to be able to mix the first gas, the second gas, and the third gas.
  • the first gas supply unit 1, the second gas supply unit 2, and the third gas supply unit 3 are connected to the mixing unit 50.
  • the first thermal decomposition unit 5 is located between the first gas supply unit 1 and the mixing unit 50.
  • the silicon carbide epitaxial substrate manufacturing apparatus 200 according to the above (11) may further include a second thermal decomposition unit 6 configured to be capable of thermally decomposing the second gas at the second temperature.
  • the second thermal decomposition unit 6 is located between the second gas supply unit 2 and the mixing unit 50.
  • the second temperature may be lower than the first temperature.
  • the second gas may contain SiH 4 . 400 degreeC or more and 800 degrees C or less may be sufficient as 2nd temperature.
  • the silicon carbide epitaxial substrate manufacturing apparatus 200 according to any one of (11) to (14) further includes a third thermal decomposition unit 7 configured to be capable of thermal decomposition of the third gas at the third temperature. You may have.
  • the third thermal decomposition unit 7 may be between the third gas supply unit 3 and the mixing unit 50.
  • the third temperature may be 600 ° C. or higher and 1000 ° C. or lower.
  • the first gas may contain C 3 H 8 .
  • the first temperature may be 1200 ° C. or higher and 1600 ° C. or lower.
  • Silicon carbide epitaxial substrate manufacturing equipment The configuration of manufacturing apparatus 200 for silicon carbide epitaxial substrate 100 according to the present embodiment will be described.
  • the manufacturing apparatus 200 is, for example, a hot wall type horizontal CVD (Chemical Vapor Deposition) apparatus.
  • the manufacturing apparatus 200 includes a reaction chamber 21, a first gas supply unit 1, a second gas supply unit 2, a third gas supply unit 3, a carrier gas supply unit 4, a first thermal decomposition unit 5, It mainly includes a second heat decomposition unit 6, a third heat decomposition unit 7, a mixing unit 50, a heating element 23, a quartz tube 24, a heat insulating material 25, and an induction heating coil 26.
  • the heating element 23 has a cylindrical shape, for example, and forms a reaction chamber 21 therein.
  • the heating element 23 is made of, for example, graphite.
  • the heat insulating material 25 surrounds the outer periphery of the heating element 23.
  • the heat insulating material 25 is provided inside the quartz tube 24 so as to be in contact with the inner peripheral surface of the quartz tube 24.
  • the induction heating coil 26 is wound, for example, along the outer peripheral surface of the quartz tube 24.
  • the induction heating coil 26 is configured to be able to supply an alternating current by an external power source (not shown). Thereby, the heating element 23 is induction-heated. As a result, the reaction chamber 21 is heated.
  • the reaction chamber 21 is a space formed by being surrounded by the heating element 23.
  • a silicon carbide single crystal substrate 10 is arranged in reaction chamber 21.
  • Reaction chamber 21 is configured to heat silicon carbide single crystal substrate 10.
  • the maximum diameter of the silicon carbide single crystal substrate is 100 mm or more.
  • the reaction chamber 21 is provided with a susceptor plate 30 that holds the silicon carbide single crystal substrate 10.
  • the susceptor plate 30 is configured to be able to rotate around the rotation shaft 22.
  • the manufacturing apparatus 200 further includes a gas introduction port 27 and a gas exhaust port 28.
  • the gas exhaust port 28 is connected to an exhaust pump (not shown).
  • the arrows in FIG. 1 indicate the gas flow.
  • the gas is introduced into the reaction chamber 21 from the gas introduction port 27 and is exhausted from the gas exhaust port 28.
  • the pressure in the reaction chamber 21 is adjusted by the balance between the gas supply amount and the gas exhaust amount.
  • the 1st gas supply part 1 is comprised so that supply of the 1st gas containing carbon is possible.
  • the first gas supply unit 1 is, for example, a gas cylinder filled with a first gas.
  • the first gas is, for example, propane (C 3 H 8 ) gas.
  • the first gas may be, for example, methane (CH 4 ) gas, ethane (C 2 H 6 ) gas, acetylene (C 2 H 2 ) gas, or the like.
  • Propane gas may be diluted with hydrogen gas.
  • the content of propane may be 10% by volume or more and 50% by volume or less.
  • a diluent gas of 30% by volume of propane and 70% by volume of hydrogen may be used. This is because diluted propane is more easily decomposed by heating.
  • the second gas supply unit 2 is configured to be able to supply a second gas containing silicon.
  • the second gas supply unit 2 is, for example, a gas cylinder filled with the second gas.
  • the second gas is, for example, silane (SiH 4) gas.
  • the second gas may be, for example, disilane (Si 2 H 6 ) gas, dichlorosilane (SiH 2 Cl 2 ) gas, trichlorosilane (SiHCl 3 ) gas, silicon tetrachloride (SiCl 4 ) gas, or the like.
  • the 3rd gas supply part 3 is comprised so that supply of the 3rd gas containing nitrogen is possible.
  • the third gas supply unit 3 is, for example, a gas cylinder filled with a third gas.
  • the third gas is doping gas containing N (nitrogen atom), for example, nitrogen (N 2) gas and ammonia (NH 3) is at least one gas. Ammonia gas is more easily pyrolyzed than nitrogen gas having a triple bond. By using ammonia gas, improvement in the in-plane uniformity of the carrier concentration can be expected.
  • the mixing unit 50 is configured to be able to mix the first gas, the second gas, and the third gas.
  • the mixing unit 50 may be a pipe in which the first gas, the second gas, and the third gas are mixed.
  • the mixing unit 50 communicates with the gas inlet 27 of the reaction chamber 21.
  • the first gas supply unit 1, the second gas supply unit 2, and the third gas supply unit 3 are connected to the mixing unit 50.
  • the carrier gas supply unit 4 is configured to be able to supply a carrier gas such as hydrogen.
  • the carrier gas supply unit 4 is a gas cylinder filled with hydrogen, for example.
  • the carrier gas supply unit 4 is connected to the mixing unit 50 by a pipe 54.
  • the first thermal decomposition unit 5 is configured to be capable of heating the first gas at the first temperature.
  • the 1st thermal decomposition part 5 is a part comprised so that the space where 1st gas flows with a resistance heater or an induction heater can be heated, for example.
  • the 1st thermal decomposition part 5 exists between the 1st gas supply part 1 and the mixing part 50, for example.
  • the first temperature is, for example, 1200 ° C. or higher and 1600 ° C. or lower, preferably 1250 ° C. or higher and 1550 ° C. or lower, and more preferably 1300 ° C. or higher and 1500 ° C. or lower.
  • the first gas supply unit 1 is connected to the first thermal decomposition unit 5 by a pipe 51.
  • the first thermal decomposition unit 5 is connected to the mixing unit 50 by a pipe 55.
  • the pipe 55 may be joined to the mixing unit 50 at the connection unit 15.
  • the second thermal decomposition unit 6 is configured to be capable of thermally decomposing the second gas at the second temperature.
  • the second thermal decomposition unit 6 is a part in which the space in which the second gas flows can be heated by, for example, a resistance heater or an induction heater.
  • the 2nd thermal decomposition part 6 exists between the 2nd gas supply part 2 and the mixing part 50, for example.
  • the second temperature is, for example, 400 ° C. or higher and 800 ° C. or lower, preferably 450 ° C. or higher and 750 ° C. or lower, and more preferably 500 ° C. or higher and 700 ° C. or lower.
  • the second temperature may be lower than the first temperature.
  • the second gas supply unit 2 is connected to the second thermal decomposition unit 6 through a pipe 52.
  • the second thermal decomposition unit 6 is connected to the mixing unit 50 by a pipe 56.
  • the pipe 56 may be joined to the mixing unit 50 at the connection unit 16.
  • the third thermal decomposition unit 7 is configured to be able to thermally decompose the third gas at the third temperature.
  • the 3rd thermal decomposition part 7 is a part comprised so that the space through which 3rd gas flows can be heated, for example with a resistance heater or an induction heater.
  • the 3rd thermal decomposition part 7 exists between the 3rd gas supply part 3 and the mixing part 50, for example.
  • the third temperature is, for example, 600 ° C. or higher and 1000 ° C. or lower, preferably 650 ° C. or higher and 950 ° C. or lower, and more preferably 700 ° C. or higher and 900 ° C. or lower.
  • the third temperature may be lower than the first temperature.
  • the third temperature may be higher than the second temperature.
  • the third gas supply unit 3 is connected to the third thermal decomposition unit 7 by a pipe 53.
  • the third thermal decomposition unit 7 is connected to the mixing unit 50 by a pipe 57.
  • the pipe 57
  • the manufacturing apparatus 200 includes the first thermal decomposition unit 5, but may not include the second thermal decomposition unit 6 and the third thermal decomposition unit 7.
  • the second gas supply unit 2 is connected to the mixing unit 50 by a pipe 52 without passing through the second thermal decomposition unit 6.
  • the third gas supply unit 3 is connected to the mixing unit 50 through a pipe 53 without passing through the third thermal decomposition unit 7. Since the configuration other than the above is substantially the same as the configuration of the manufacturing apparatus 200 according to the present embodiment, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated.
  • the manufacturing apparatus 200 includes the first thermal decomposition unit 5 and the third thermal decomposition unit 7, but may not include the second thermal decomposition unit 6.
  • the second gas supply unit 2 is connected to the mixing unit 50 through a pipe 52 without going through the second thermal decomposition unit 6. Since the configuration other than the above is substantially the same as the configuration of the manufacturing apparatus 200 according to the present embodiment, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated.
  • the manufacturing apparatus 200 includes the first thermal decomposition unit 5 and the second thermal decomposition unit 6, but may not include the third thermal decomposition unit 7.
  • the third gas supply unit 3 is connected to the mixing unit 50 through a pipe 53 without passing through the third thermal decomposition unit 7. Since the configuration other than the above is substantially the same as the configuration of the manufacturing apparatus 200 according to the present embodiment, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated.
  • a step of placing a silicon carbide single crystal substrate is performed.
  • a silicon carbide single crystal of polytype 6H is manufactured by a sublimation method.
  • silicon carbide single crystal substrate 10 is prepared by slicing the silicon carbide single crystal with, for example, a wire saw (see FIG. 6).
  • Silicon carbide single crystal substrate 10 has a first main surface 41 and a second main surface 42 opposite to the first main surface 41.
  • the polytype of the silicon carbide single crystal is, for example, 4H—SiC. 4H—SiC is superior to other polytypes in terms of electron mobility, dielectric breakdown field strength, and the like.
  • Silicon carbide single crystal substrate 10 contains an n-type impurity such as nitrogen, for example.
  • Silicon carbide single crystal substrate 10 has an n-type conductivity, for example.
  • the first main surface 41 is, for example, a surface inclined by an angle of 8 ° or less from the ⁇ 0001 ⁇ plane or the ⁇ 0001 ⁇ plane.
  • the first principal surface 41 may be a (0001) plane or a plane inclined by an angle of 8 ° or less from the (0001) plane, or a (000-1) plane or (000-1).
  • the surface may be inclined by an angle of 8 ° or less from the surface.
  • the inclination direction of the normal line of the first main surface 41 is, for example, the ⁇ 11-20> direction.
  • the inclination angle (off angle) from the ⁇ 0001 ⁇ plane may be 1 ° or more, or 2 ° or more.
  • the off-angle may be 7 ° or less, 6 ° or less, or 4 ° or less.
  • the maximum diameter (diameter) of first main surface 41 of silicon carbide single crystal substrate 10 is 100 mm or more.
  • the diameter may be 150 mm or more, 200 mm or more, or 250 mm or more.
  • the upper limit of the diameter is not particularly limited, but the upper limit of the diameter may be 300 mm, for example.
  • silicon carbide single crystal substrate 10 is placed in the reaction chamber 21. As shown in FIG. 1, silicon carbide single crystal substrate 10 is disposed in a recess of susceptor plate 30. Next, silicon carbide layer 20 is formed by epitaxial growth on silicon carbide single crystal substrate 10 using manufacturing apparatus 200.
  • the temperature rise of the silicon carbide single crystal substrate 10 is started.
  • hydrogen (H 2 ) gas which is a carrier gas
  • the carrier gas supplied to the mixing unit 50 is introduced into the reaction chamber 21.
  • the flow rate of the hydrogen gas is adjusted by, for example, MFC (Mass Flow Controller). By this operation, for example, reduction of residual nitrogen in the reaction chamber 21 is expected.
  • the heating element 23 is heated by applying an AC voltage to the induction heating coil 26.
  • the first gas is supplied from the first gas supply unit 1 to the first thermal decomposition unit 5 through the pipe 51.
  • the 1st thermal decomposition part 5 the 1st gas containing carbon is thermally decomposed.
  • the first gas is thermally decomposed at the first temperature.
  • the thermally decomposed first gas is sent to the mixing unit 50 through the pipe 55.
  • an arrow 11 indicates the flow of the first gas before being thermally decomposed
  • an arrow 31 indicates the flow of the first gas after being thermally decomposed.
  • the first gas is, for example, propane (C 3 H 8 ) gas.
  • the first gas may be, for example, methane (CH 4 ) gas, ethane (C 2 H 6 ) gas, acetylene (C 2 H 2 ) gas, or the like.
  • the first temperature is, for example, 1200 ° C. or higher and 1600 ° C. or lower, preferably 1250 ° C. or higher and 1550 ° C. or lower, and more preferably 1300 ° C. or higher and 1500 ° C. or lower.
  • the second gas is supplied from the second gas supply unit 2 to the second thermal decomposition unit 6 through the pipe 52.
  • the second gas containing silicon is thermally decomposed.
  • the second gas is thermally decomposed at the second temperature.
  • the thermally decomposed second gas is sent to the mixing unit 50 through the pipe 56.
  • an arrow 12 indicates the flow of the second gas before being thermally decomposed
  • an arrow 32 indicates the flow of the second gas after being thermally decomposed.
  • the second gas is, for example, silane (SiH 4 ) gas.
  • the second gas may be, for example, disilane (Si 2 H 6 ) gas, dichlorosilane (SiH 2 Cl 2 ) gas, trichlorosilane (SiHCl 3 ) gas, silicon tetrachloride (SiCl 4 ) gas, or the like.
  • the second temperature is, for example, 400 ° C. or higher and 800 ° C. or lower, preferably 450 ° C. or higher and 750 ° C. or lower, and more preferably 500 ° C. or higher and 700 ° C. or lower.
  • the second temperature may be lower than the first temperature.
  • the third gas is supplied from the third gas supply unit 3 to the third thermal decomposition unit 7 through the pipe 53.
  • the 3rd gas containing nitrogen is thermally decomposed.
  • the third gas is thermally decomposed at the third temperature.
  • the thermally decomposed third gas is sent to the mixing unit 50 through the pipe 57.
  • an arrow 13 indicates the flow of the third gas before being thermally decomposed
  • an arrow 33 indicates the flow of the third gas after being thermally decomposed.
  • the third gas is, for example, at least one of nitrogen gas and ammonia gas.
  • the third temperature is, for example, 600 ° C. or higher and 1000 ° C. or lower, preferably 650 ° C. or higher and 950 ° C. or lower, and more preferably 700 ° C. or higher and 900 ° C. or lower.
  • the third temperature may be lower than the first temperature.
  • the third temperature may be higher than the second temperature.
  • a step of generating a mixed gas (S2: FIG. 5) is performed.
  • a mixed gas is generated by mixing a first gas containing carbon, a second gas containing silicon, a third gas containing nitrogen, and a carrier gas.
  • the first gas is in a thermally decomposed state.
  • the second gas is in a state of being thermally decomposed or not being thermally decomposed.
  • the third gas is in a state of being thermally decomposed or not being thermally decomposed.
  • a first gas obtained by thermally decomposing propane, a second gas obtained by thermally decomposing silane, a third gas obtained by thermally decomposing ammonia, and hydrogen gas are mixed.
  • a first gas that has been pyrolyzed, a second gas that has not been pyrolyzed, a third gas that has not been pyrolyzed, and a carrier gas may be mixed.
  • the first gas is in a thermally decomposed state
  • the second gas is not thermally decomposed
  • the third gas is not thermally decomposed.
  • the first gas that has been thermally decomposed, the second gas that has not been thermally decomposed, the third gas that has been thermally decomposed, and the carrier gas may be mixed.
  • the first gas is in a state of being thermally decomposed, the second gas is in a state of not being thermally decomposed, and the third gas is in a state of being thermally decomposed.
  • a first gas that has been thermally decomposed, a second gas that has been thermally decomposed, a third gas that has not been thermally decomposed, and a carrier gas may be mixed.
  • the first gas is in a thermally decomposed state
  • the second gas is in a thermally decomposed state
  • the third gas is in a state in which it is not thermally decomposed.
  • a mixed gas in which the first gas, the second gas, and the third gas are mixed is introduced into the reaction chamber 21.
  • the mixed gas may include a carrier gas.
  • the mixed gas is introduced into the reaction chamber 21 in a state where the temperature in the reaction chamber 21 is about 1600 ° C., for example.
  • the C / Si ratio of the mixed gas may be 0.9, for example.
  • the silicon carbide single crystal substrate 10 may rotate around the rotation shaft 22.
  • silicon carbide layer 20 is formed on silicon carbide single crystal substrate 10 (S4: FIG. 5). Silicon carbide layer 20 is an epitaxial layer.
  • Silicon carbide layer 20 has a fourth main surface 44 in contact with silicon carbide single crystal substrate 10 and a third main surface 43 opposite to fourth main surface 44.
  • silicon carbide epitaxial substrate 100 (see FIG. 7) including silicon carbide single crystal substrate 10 and silicon carbide layer 20 is manufactured.
  • the in-plane uniformity of the carrier concentration is, for example, within 3%.
  • the carrier concentration can be measured by, for example, the CV method.
  • Each measurement point is arranged at substantially equal intervals on a cross passing through the center of the third main surface 43.
  • the in-plane uniformity of the carrier concentration is, for example, a value expressed as a percentage obtained by dividing the standard deviation of the carrier concentration at all measurement locations by the average value of the carrier concentration.
  • the method for manufacturing a silicon carbide semiconductor device mainly includes an epitaxial substrate preparation step (S10: FIG. 8) and a substrate processing step (S20: FIG. 8).
  • an epitaxial substrate preparation step (S10: FIG. 8) is performed. Specifically, silicon carbide epitaxial substrate 100 is prepared by the above-described method for manufacturing a silicon carbide epitaxial substrate (see FIG. 7).
  • a substrate processing step (S20: FIG. 8) is performed.
  • a silicon carbide semiconductor device is manufactured by processing a silicon carbide epitaxial substrate.
  • “Processing” includes, for example, various processes such as ion implantation, heat treatment, etching, oxide film formation, electrode formation, and dicing. That is, the substrate processing step may include at least one of ion implantation, heat treatment, etching, oxide film formation, electrode formation, and dicing.
  • the substrate processing step (S20: FIG. 8) includes an ion implantation step (S21: FIG. 8), an oxide film formation step (S22: FIG. 8), an electrode formation step (S23: FIG. 8), and a dicing step (S24: FIG. 8). including.
  • an ion implantation step (S21: FIG. 8) is performed.
  • a p-type impurity such as aluminum (Al) is implanted into the third main surface 43 on which a mask (not shown) having an opening is formed.
  • body region 132 having p-type conductivity is formed.
  • an n-type impurity such as phosphorus (P) is implanted into a predetermined position in body region 132.
  • a source region 133 having n-type conductivity is formed.
  • a p-type impurity such as aluminum is implanted into a predetermined position in the source region 133.
  • a contact region 134 having a p-type conductivity is formed (see FIG. 9).
  • Source region 133 is separated from drift region 131 by body region 132.
  • Ion implantation may be performed by heating silicon carbide epitaxial substrate 100 to about 300 ° C. or more and 600 ° C. or less. After the ion implantation, activation annealing is performed on silicon carbide epitaxial substrate 100. By the activation annealing, the impurities injected into the silicon carbide layer 20 are activated, and carriers are generated in each region.
  • the atmosphere of activation annealing may be, for example, an argon (Ar) atmosphere.
  • the activation annealing temperature may be about 1800 ° C., for example.
  • the activation annealing time may be about 30 minutes, for example.
  • oxide film forming step (S22: FIG. 8) is performed.
  • silicon carbide epitaxial substrate 100 is heated in an atmosphere containing oxygen, whereby oxide film 136 is formed on third main surface 43 (see FIG. 10).
  • Oxide film 136 is made of, for example, silicon dioxide (SiO 2 ).
  • the oxide film 136 functions as a gate insulating film.
  • the temperature of the thermal oxidation treatment may be about 1300 ° C., for example.
  • the thermal oxidation treatment time may be about 30 minutes, for example.
  • heat treatment may be performed in a nitrogen atmosphere.
  • the heat treatment may be performed at about 1100 ° C. for about 1 hour in an atmosphere such as nitric oxide (NO) or nitrous oxide (N 2 O).
  • heat treatment may be performed in an argon atmosphere.
  • the heat treatment may be performed in an argon atmosphere at about 1100 to 1500 ° C. for about 1 hour.
  • the first electrode 141 is formed on the oxide film 136.
  • the first electrode 141 functions as a gate electrode.
  • the first electrode 141 is formed by, for example, a CVD method.
  • the first electrode 141 is made of, for example, polysilicon containing impurities and having conductivity.
  • the first electrode 141 is formed at a position facing the source region 133 and the body region 132.
  • Interlayer insulating film 137 covering the first electrode 141 is formed.
  • Interlayer insulating film 137 is formed by, for example, a CVD method.
  • Interlayer insulating film 137 is made of, for example, silicon dioxide.
  • the interlayer insulating film 137 is formed so as to be in contact with the first electrode 141 and the oxide film 136.
  • the oxide film 136 and the interlayer insulating film 137 at predetermined positions are removed by etching. As a result, the source region 133 and the contact region 134 are exposed from the oxide film 136.
  • the second electrode 142 is formed on the exposed portion by sputtering.
  • the second electrode 142 functions as a source electrode.
  • Second electrode 142 is made of, for example, titanium, aluminum, silicon, or the like.
  • second electrode 142 and silicon carbide epitaxial substrate 100 are heated at a temperature of about 900 to 1100 ° C., for example. Thereby, second electrode 142 and silicon carbide epitaxial substrate 100 come into ohmic contact.
  • the wiring layer 138 is formed so as to be in contact with the second electrode 142.
  • the wiring layer 138 is made of a material containing aluminum, for example.
  • the third electrode 143 is formed on the second main surface 42.
  • the third electrode 143 functions as a drain electrode.
  • Third electrode 143 is made of, for example, an alloy containing nickel and silicon (eg, NiSi).
  • a dicing step (S24: FIG. 8) is performed.
  • silicon carbide epitaxial substrate 100 is diced along a dicing line, whereby silicon carbide epitaxial substrate 100 is divided into a plurality of semiconductor chips.
  • silicon carbide semiconductor device 300 is manufactured (see FIG. 11).
  • the method for manufacturing the silicon carbide semiconductor device according to the present disclosure has been described by exemplifying the MOSFET, but the manufacturing method according to the present disclosure is not limited to this.
  • the manufacturing method according to the present disclosure is applicable to various silicon carbide semiconductor devices such as IGBT (Insulated Gate Bipolar Transistor), SBD (Schottky Barrier Diode), thyristor, GTO (Gate Turn Off thyristor), and PiN diode.
  • IGBT Insulated Gate Bipolar Transistor
  • SBD Schottky Barrier Diode
  • thyristor thyristor
  • GTO Gate Turn Off thyristor
  • PiN diode PiN diode

Abstract

A method for producing a silicon carbide epitaxial substrate according to the present disclosure comprises the following steps: a step wherein a silicon carbide single crystal substrate having a diameter of 100 mm or more is arranged within a reaction chamber; a step wherein a mixed gas is produced by mixing a first gas that contains carbon and is in a thermally decomposed state, a second gas containing silicon and a third gas containing nitrogen; a step wherein the mixed gas is introduced into the reaction chamber; and a step wherein a silicon carbide layer is formed on the silicon carbide single crystal substrate by heating the mixed gas within the reaction chamber.

Description

炭化珪素エピタキシャル基板の製造方法、炭化珪素半導体装置の製造方法および炭化珪素エピタキシャル基板の製造装置Method for manufacturing silicon carbide epitaxial substrate, method for manufacturing silicon carbide semiconductor device, and device for manufacturing silicon carbide epitaxial substrate
　本開示は、炭化珪素エピタキシャル基板の製造方法、炭化珪素半導体装置の製造方法および炭化珪素エピタキシャル基板の製造装置に関する。本出願は、２０１５年９月２５日に出願した日本特許出願である特願２０１５－１８７９２２号に基づく優先権を主張し、当該日本特許出願に記載された全ての記載内容を援用するものである。 The present disclosure relates to a method for manufacturing a silicon carbide epitaxial substrate, a method for manufacturing a silicon carbide semiconductor device, and a device for manufacturing a silicon carbide epitaxial substrate. This application claims priority based on Japanese Patent Application No. 2015-187922, a Japanese patent application filed on September 25, 2015, and incorporates all the content described in the Japanese patent application. .
　特開２０１４－１７０８９１号公報（特許文献１）には、炭化珪素単結晶基板上に炭化珪素層をエピタキシャル成長させる方法が開示されている。 Japanese Patent Laying-Open No. 2014-170891 (Patent Document 1) discloses a method of epitaxially growing a silicon carbide layer on a silicon carbide single crystal substrate.
特開２０１４－１７０８９１号公報JP 2014-170891 A
　本開示に係る炭化珪素エピタキシャル基板の製造方法は以下の工程を備えている。反応室内に、直径１００ｍｍ以上の炭化珪素単結晶基板が配置される。炭素を含み加熱分解された状態の第１ガスと、珪素を含む第２ガスと、窒素を含む第３ガスとを混合することによって混合ガスが生成される。混合ガスが反応室に導入される。反応室内で混合ガスを加熱することにより、炭化珪素単結晶基板上に炭化珪素層が形成される。 The method for manufacturing a silicon carbide epitaxial substrate according to the present disclosure includes the following steps. A silicon carbide single crystal substrate having a diameter of 100 mm or more is disposed in the reaction chamber. A mixed gas is generated by mixing the first gas containing carbon and thermally decomposed, the second gas containing silicon, and the third gas containing nitrogen. A mixed gas is introduced into the reaction chamber. By heating the mixed gas in the reaction chamber, a silicon carbide layer is formed on the silicon carbide single crystal substrate.
　本開示に係る炭化珪素エピタキシャル基板の製造装置は、反応室と、第１ガス供給部と、第２ガス供給部と、第３ガス供給部と、第１加熱分解部と、混合部とを備えている。反応室は、炭化珪素単結晶基板を加熱可能に構成されている。第１ガス供給部は、炭素を含む第１ガスを供給可能に構成されている。第２ガス供給部は、珪素を含む第２ガスを供給可能に構成されている。第３ガス供給部は、窒素を含む第３ガスを供給可能に構成されている。第１加熱分解部は、第１温度で、第１ガスを加熱可能に構成されている。混合部は、第１ガスと、第２ガスと、第３ガスとを混合可能に構成されている。第１ガス供給部と、第２ガス供給部と、第３ガス供給部とは、混合部に繋がれている。第１加熱分解部は、第１ガス供給部と混合部との間にある。 An apparatus for manufacturing a silicon carbide epitaxial substrate according to the present disclosure includes a reaction chamber, a first gas supply unit, a second gas supply unit, a third gas supply unit, a first thermal decomposition unit, and a mixing unit. ing. The reaction chamber is configured to heat the silicon carbide single crystal substrate. The first gas supply unit is configured to be able to supply a first gas containing carbon. The second gas supply unit is configured to be able to supply a second gas containing silicon. The third gas supply unit is configured to be able to supply a third gas containing nitrogen. The first thermal decomposition unit is configured to be capable of heating the first gas at the first temperature. The mixing unit is configured to be able to mix the first gas, the second gas, and the third gas. The first gas supply unit, the second gas supply unit, and the third gas supply unit are connected to the mixing unit. The first thermal decomposition unit is between the first gas supply unit and the mixing unit.
図１は、本実施形態に係る炭化珪素エピタキシャル基板の製造装置の構成を示す一部断面模式図である。FIG. 1 is a partial schematic cross-sectional view showing a configuration of a silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment. 図２は、本実施形態に係る炭化珪素エピタキシャル基板の製造装置の第１変形例の構成を示す一部断面模式図である。FIG. 2 is a partial cross-sectional schematic diagram showing the configuration of the first modification of the silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment. 図３は、本実施形態に係る炭化珪素エピタキシャル基板の製造装置の第２変形例の構成を示す一部断面模式図である。FIG. 3 is a partial cross-sectional schematic diagram showing the configuration of the second modification of the silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment. 図４は、本実施形態に係る炭化珪素エピタキシャル基板の製造装置の第３変形例の構成を示す一部断面模式図である。FIG. 4 is a partial cross-sectional schematic diagram showing the configuration of the third modification of the silicon carbide epitaxial substrate manufacturing apparatus according to the present embodiment. 図５は、本実施形態に係る炭化珪素エピタキシャル基板の製造方法を概略的に示すフローチャートである。FIG. 5 is a flowchart schematically showing a method for manufacturing the silicon carbide epitaxial substrate according to the present embodiment. 図６は、本実施形態に係る炭化珪素エピタキシャル基板の製造方法の第１工程を示す断面模式図である。FIG. 6 is a schematic cross-sectional view showing a first step of the method for manufacturing the silicon carbide epitaxial substrate according to the present embodiment. 図７は、本実施形態に係る炭化珪素エピタキシャル基板の製造方法の第２工程を示す断面模式図である。FIG. 7 is a schematic cross-sectional view showing a second step of the method for manufacturing the silicon carbide epitaxial substrate according to the present embodiment. 図８は、本実施形態に係る炭化珪素半導体装置の製造方法を概略的に示すフローチャートである。FIG. 8 is a flowchart schematically showing a method for manufacturing the silicon carbide semiconductor device according to the present embodiment. 図９は、本実施形態に係る炭化珪素半導体装置の製造方法の第１工程を示す断面模式図である。FIG. 9 is a schematic cross-sectional view showing a first step of the method for manufacturing the silicon carbide semiconductor device according to this embodiment. 図１０は、本実施形態に係る炭化珪素半導体装置の製造方法の第２工程を示す断面模式図である。FIG. 10 is a schematic cross-sectional view showing a second step of the method for manufacturing the silicon carbide semiconductor device according to this embodiment. 図１１は、本実施形態に係る炭化珪素半導体装置の製造方法の第３工程を示す断面模式図である。FIG. 11 is a schematic cross-sectional view showing a third step of the method for manufacturing the silicon carbide semiconductor device according to this embodiment.
　［本開示の実施形態の概要］
　まず本開示の実施形態について説明する。以下の説明では、同一または対応する要素には同一の符号を付し、それらについて同じ説明は繰り返さない。本明細書の結晶学的記載においては、個別方位を［］、集合方位を＜＞、個別面を（）、集合面を｛｝でそれぞれ示す。結晶学上の指数が負であることは、通常、数字の上に”－”（バー）を付すことによって表現されるが、本明細書では数字の前に負の符号を付すことによって結晶学上の負の指数を表現する。 [Outline of Embodiment of the Present Disclosure]
First, an embodiment of the present disclosure will be described. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated. In the crystallographic description of the present specification, the individual orientation is indicated by [], the collective orientation is indicated by <>, the individual plane is indicated by (), and the collective plane is indicated by {}. A negative crystallographic index is usually expressed by adding a “-” (bar) above a number, but in this specification the crystallographic index is preceded by a negative sign. Represents the negative exponent above.
　（１）本開示に係る炭化珪素エピタキシャル基板１００の製造方法は以下の工程を備えている。反応室２１内に、直径１００ｍｍ以上の炭化珪素単結晶基板１０が配置される。炭素を含み加熱分解された状態の第１ガスと、珪素を含む第２ガスと、窒素を含む第３ガスとを混合することによって混合ガスが生成される。混合ガスが反応室２１に導入される。反応室２１内で混合ガスを加熱することにより、炭化珪素単結晶基板１０上に炭化珪素層２０が形成される。 (1) A method for manufacturing silicon carbide epitaxial substrate 100 according to the present disclosure includes the following steps. In reaction chamber 21, silicon carbide single crystal substrate 10 having a diameter of 100 mm or more is arranged. A mixed gas is generated by mixing the first gas containing carbon and thermally decomposed, the second gas containing silicon, and the third gas containing nitrogen. A mixed gas is introduced into the reaction chamber 21. By heating the mixed gas in reaction chamber 21, silicon carbide layer 20 is formed on silicon carbide single crystal substrate 10.
　炭化珪素層をエピタキシャル成長により形成する際、たとえば、炭素を含むガスと、珪素を含むガスと、ドーパントガスと、キャリアガスとが反応室に供給される。珪素を含むガスおよびドーパントガスと比較して、炭素を含むガスは分解されづらい。そのため、反応室内において、炭化珪素単結晶基板に対して上流側のガスのＣ／Ｓｉ比は、下流側のガスのＣ／Ｓｉ比よりも低下する傾向にある。その結果、炭化珪素単結晶基板の表面上におけるＣ／Ｓｉ比の均一性が悪化する。 When the silicon carbide layer is formed by epitaxial growth, for example, a gas containing carbon, a gas containing silicon, a dopant gas, and a carrier gas are supplied to the reaction chamber. Compared with a gas containing silicon and a dopant gas, a gas containing carbon is difficult to be decomposed. Therefore, in the reaction chamber, the C / Si ratio of the upstream gas with respect to the silicon carbide single crystal substrate tends to be lower than the C / Si ratio of the downstream gas. As a result, the uniformity of the C / Si ratio on the surface of the silicon carbide single crystal substrate is deteriorated.
　ドーパントの窒素原子は、炭化珪素結晶の炭素サイトと置換されることにより炭化珪素結晶中に導入される。Ｃ／Ｓｉ比が低い程、窒素原子が炭化珪素結晶中に取り込まれ易い。そのため、炭化珪素単結晶基板の表面上におけるＣ／Ｓｉ比の均一性が悪化すると、炭化珪素単結晶基板の表面と平行な方向における炭化珪素層中の窒素原子の濃度の均一性が悪化する。 The nitrogen atom of the dopant is introduced into the silicon carbide crystal by replacing the carbon site of the silicon carbide crystal. The lower the C / Si ratio, the easier the nitrogen atoms are taken into the silicon carbide crystal. Therefore, when the uniformity of the C / Si ratio on the surface of the silicon carbide single crystal substrate is deteriorated, the uniformity of the concentration of nitrogen atoms in the silicon carbide layer in the direction parallel to the surface of the silicon carbide single crystal substrate is deteriorated.
　上記知見に基づき、発明者は、炭素を含むガスを反応室に供給する前に、炭素を含むガスを予め選択的に加熱分解することにより、反応室内において、炭化珪素単結晶基板の表面上におけるＣ／Ｓｉの均一性を向上可能であることを見出した。結果として、炭化珪素単結晶基板の表面と平行な方向における炭化珪素層中のキャリア濃度の均一性を向上することができる。言い換えれば、炭化珪素層のキャリア濃度の面内均一性を向上することができる。 Based on the above knowledge, the inventor can selectively decompose the gas containing carbon in advance in the reaction chamber on the surface of the silicon carbide single crystal substrate before supplying the gas containing carbon to the reaction chamber. It has been found that the uniformity of C / Si can be improved. As a result, the uniformity of the carrier concentration in the silicon carbide layer in the direction parallel to the surface of the silicon carbide single crystal substrate can be improved. In other words, the in-plane uniformity of the carrier concentration of the silicon carbide layer can be improved.
　（２）上記（１）に係る炭化珪素エピタキシャル基板１００の製造方法の混合ガスを生成する工程において、第２ガスは加熱分解された状態であってもよい。 (2) In the step of generating the mixed gas in the method for manufacturing the silicon carbide epitaxial substrate 100 according to the above (1), the second gas may be in a thermally decomposed state.
　（３）上記（１）に係る炭化珪素エピタキシャル基板１００の製造方法の混合ガスを生成する工程において、第３ガスは加熱分解された状態であってもよい。 (3) In the step of generating the mixed gas in the method for manufacturing the silicon carbide epitaxial substrate 100 according to (1) above, the third gas may be in a thermally decomposed state.
　（４）上記（２）に係る炭化珪素エピタキシャル基板１００の製造方法の混合ガスを生成する工程において、第３ガスは加熱分解された状態であってもよい。 (4) In the step of generating the mixed gas in the method for manufacturing the silicon carbide epitaxial substrate 100 according to (2) above, the third gas may be in a thermally decomposed state.
　（５）上記（１）～（４）のいずれかに係る炭化珪素エピタキシャル基板１００の製造方法において、第１ガスは、Ｃ３Ｈ８を含み、第１ガスは１２００℃以上１６００℃以下の温度で加熱分解された状態であってもよい。 (5) In the method for manufacturing silicon carbide epitaxial substrate 100 according to any one of (1) to (4), the first gas contains C 3 H 8 and the first gas has a temperature of 1200 ° C. or higher and 1600 ° C. or lower. It may be in a state where it is thermally decomposed at.
　（６）上記（５）に係る炭化珪素エピタキシャル基板１００の製造方法において、第１ガスはＨ２で希釈されたＣ３Ｈ８を含んでいてもよい。 (6) In the method for manufacturing silicon carbide epitaxial substrate 100 according to (5) above, the first gas may contain C 3 H 8 diluted with H 2 .
　（７）上記（２）に係る炭化珪素エピタキシャル基板１００の製造方法において、第２ガスはＳｉＨ４を含み、第２ガスは４００℃以上８００℃以下の温度で加熱分解された状態であってもよい。 (7) In the method for manufacturing silicon carbide epitaxial substrate 100 according to (2) above, the second gas contains SiH 4 , and the second gas is in a state of being thermally decomposed at a temperature of 400 ° C. or higher and 800 ° C. or lower. Good.
　（８）上記（３）に係る炭化珪素エピタキシャル基板１００の製造方法において、第３ガスは、Ｎ２およびＮＨ３の少なくともいずれかを含み、第３ガスは６００℃以上１０００℃以下の温度で加熱分解された状態であってもよい。 (8) In the method for manufacturing silicon carbide epitaxial substrate 100 according to (3), the third gas includes at least one of N 2 and NH 3 , and the third gas is heated at a temperature of 600 ° C. or higher and 1000 ° C. or lower. It may be in a disassembled state.
　（９）上記（４）に係る炭化珪素エピタキシャル基板１００の製造方法において、第３ガスは、Ｎ２およびＮＨ３の少なくともいずれかを含み、第３ガスは６００℃以上１０００℃以下の温度で加熱分解された状態であってもよい。 (9) In the method for manufacturing silicon carbide epitaxial substrate 100 according to (4), the third gas includes at least one of N 2 and NH 3 , and the third gas is heated at a temperature of 600 ° C. or higher and 1000 ° C. or lower. It may be in a disassembled state.
　（１０）本開示に係る炭化珪素半導体装置３００の製造方法は以下の工程を備えている。上記（１）～（９）のいずれか１項に記載の方法で製造された炭化珪素エピタキシャル基板１００が準備される。炭化珪素エピタキシャル基板１００が加工される。 (10) The method for manufacturing the silicon carbide semiconductor device 300 according to the present disclosure includes the following steps. A silicon carbide epitaxial substrate 100 manufactured by the method described in any one of (1) to (9) above is prepared. Silicon carbide epitaxial substrate 100 is processed.
　（１１）本開示に係る炭化珪素エピタキシャル基板１００の製造装置２００は、反応室２１と、第１ガス供給部１と、第２ガス供給部２と、第３ガス供給部３と、第１加熱分解部５と、混合部５０とを備えている。反応室２１は、炭化珪素単結晶基板１０を加熱可能に構成されている。第１ガス供給部１は、炭素を含む第１ガスを供給可能に構成されている。第２ガス供給部２は、珪素を含む第２ガスを供給可能に構成されている。第３ガス供給部３は、窒素を含む第３ガスを供給可能に構成されている。第１加熱分解部５は、第１温度で、第１ガスを加熱可能に構成されている。混合部５０は、第１ガスと、第２ガスと、第３ガスとを混合可能に構成されている。第１ガス供給部１と、第２ガス供給部２と、第３ガス供給部３とは、混合部５０に繋がれている。第１加熱分解部５は、第１ガス供給部１と混合部５０との間にある。 (11) The silicon carbide epitaxial substrate 100 manufacturing apparatus 200 according to the present disclosure includes a reaction chamber 21, a first gas supply unit 1, a second gas supply unit 2, a third gas supply unit 3, and a first heating. A decomposition unit 5 and a mixing unit 50 are provided. Reaction chamber 21 is configured to heat silicon carbide single crystal substrate 10. The 1st gas supply part 1 is comprised so that supply of the 1st gas containing carbon is possible. The second gas supply unit 2 is configured to be able to supply a second gas containing silicon. The 3rd gas supply part 3 is comprised so that supply of the 3rd gas containing nitrogen is possible. The first thermal decomposition unit 5 is configured to be able to heat the first gas at the first temperature. The mixing unit 50 is configured to be able to mix the first gas, the second gas, and the third gas. The first gas supply unit 1, the second gas supply unit 2, and the third gas supply unit 3 are connected to the mixing unit 50. The first thermal decomposition unit 5 is located between the first gas supply unit 1 and the mixing unit 50.
　（１２）上記（１１）に係る炭化珪素エピタキシャル基板の製造装置２００は、第２温度で、第２ガスを加熱分解可能に構成された第２加熱分解部６をさらに備えていてもよい。第２加熱分解部６は、第２ガス供給部２と混合部５０との間にある。 (12) The silicon carbide epitaxial substrate manufacturing apparatus 200 according to the above (11) may further include a second thermal decomposition unit 6 configured to be capable of thermally decomposing the second gas at the second temperature. The second thermal decomposition unit 6 is located between the second gas supply unit 2 and the mixing unit 50.
　（１３）上記（１２）に係る炭化珪素エピタキシャル基板の製造装置２００において、第２温度は、第１温度より低くてもよい。 (13) In the silicon carbide epitaxial substrate manufacturing apparatus 200 according to (12) above, the second temperature may be lower than the first temperature.
　（１４）上記（１２）または（１３）に係る炭化珪素エピタキシャル基板の製造装置２００において、第２ガスは、ＳｉＨ４を含んでいてもよい。第２温度は、４００℃以上８００℃以下であってもよい。 (14) In silicon carbide epitaxial substrate manufacturing apparatus 200 according to (12) or (13) above, the second gas may contain SiH 4 . 400 degreeC or more and 800 degrees C or less may be sufficient as 2nd temperature.
　（１５）上記（１１）～（１４）のいずれかに係る炭化珪素エピタキシャル基板の製造装置２００は、第３温度で、第３ガスを加熱分解可能に構成された第３加熱分解部７をさらに備えていてもよい。第３加熱分解部７は、第３ガス供給部３と混合部５０との間にあってもよい。 (15) The silicon carbide epitaxial substrate manufacturing apparatus 200 according to any one of (11) to (14) further includes a third thermal decomposition unit 7 configured to be capable of thermal decomposition of the third gas at the third temperature. You may have. The third thermal decomposition unit 7 may be between the third gas supply unit 3 and the mixing unit 50.
　（１６）上記（１５）に係る炭化珪素エピタキシャル基板の製造装置２００において、第３温度は、６００℃以上１０００℃以下であってもよい。 (16) In the silicon carbide epitaxial substrate manufacturing apparatus 200 according to (15), the third temperature may be 600 ° C. or higher and 1000 ° C. or lower.
　（１７）上記（１１）～（１６）のいずれかに係る炭化珪素エピタキシャル基板の製造装置２００において、第１ガスは、Ｃ３Ｈ８を含んでいてもよい。第１温度は、１２００℃以上１６００℃以下であってもよい。 (17) In the silicon carbide epitaxial substrate manufacturing apparatus 200 according to any of (11) to (16) above, the first gas may contain C 3 H 8 . The first temperature may be 1200 ° C. or higher and 1600 ° C. or lower.
　［本開示の実施形態の詳細］
　以下、本開示の一実施形態（以下「本実施形態」とも記す）について説明する。ただし本実施形態はこれらに限定されるものではない。 [Details of Embodiment of the Present Disclosure]
Hereinafter, an embodiment of the present disclosure (hereinafter also referred to as “the present embodiment”) will be described. However, this embodiment is not limited to these.
　（炭化珪素エピタキシャル基板の製造装置）
　本実施形態に係る炭化珪素エピタキシャル基板１００の製造装置２００の構成について説明する。 (Silicon carbide epitaxial substrate manufacturing equipment)
The configuration of manufacturing apparatus 200 for silicon carbide epitaxial substrate 100 according to the present embodiment will be described.
　図１に示されるように、製造装置２００は、たとえばホットウォール方式の横型ＣＶＤ（Ｃｈｅｍｉｃａｌ　Ｖａｐｏｒ　Ｄｅｐｏｓｉｔｉｏｎ）装置である。製造装置２００は、反応室２１と、第１ガス供給部１と、第２ガス供給部２と、第３ガス供給部３と、キャリアガス供給部４と、第１加熱分解部５と、第２加熱分解部６と、第３加熱分解部７と、混合部５０と、発熱体２３、石英管２４、断熱材２５、誘導加熱コイル２６とを主に有している。 As shown in FIG. 1, the manufacturing apparatus 200 is, for example, a hot wall type horizontal CVD (Chemical Vapor Deposition) apparatus. The manufacturing apparatus 200 includes a reaction chamber 21, a first gas supply unit 1, a second gas supply unit 2, a third gas supply unit 3, a carrier gas supply unit 4, a first thermal decomposition unit 5, It mainly includes a second heat decomposition unit 6, a third heat decomposition unit 7, a mixing unit 50, a heating element 23, a quartz tube 24, a heat insulating material 25, and an induction heating coil 26.
　発熱体２３は、たとえば筒状の形状を有しており、内部に反応室２１を形成している。発熱体２３は、たとえば黒鉛製である。断熱材２５は、発熱体２３の外周を取り囲んでいる。断熱材２５は、石英管２４の内周面に接するように石英管２４の内部に設けられている。誘導加熱コイル２６は、たとえば石英管２４の外周面に沿って巻回されている。誘導加熱コイル２６は、外部電源（図示せず）により、交流電流が供給可能に構成されている。これにより、発熱体２３が誘導加熱される。結果として、反応室２１が加熱される。 The heating element 23 has a cylindrical shape, for example, and forms a reaction chamber 21 therein. The heating element 23 is made of, for example, graphite. The heat insulating material 25 surrounds the outer periphery of the heating element 23. The heat insulating material 25 is provided inside the quartz tube 24 so as to be in contact with the inner peripheral surface of the quartz tube 24. The induction heating coil 26 is wound, for example, along the outer peripheral surface of the quartz tube 24. The induction heating coil 26 is configured to be able to supply an alternating current by an external power source (not shown). Thereby, the heating element 23 is induction-heated. As a result, the reaction chamber 21 is heated.
　反応室２１は、発熱体２３に取り囲まれて形成された空間である。反応室２１内には、炭化珪素単結晶基板１０が配置される。反応室２１は、炭化珪素単結晶基板１０を加熱可能に構成されている。炭化珪素単結晶基板の最大径は１００ｍｍ以上である。反応室２１には、炭化珪素単結晶基板１０を保持するサセプタプレート３０が設けられている。サセプタプレート３０は、回転軸２２の周りを自転可能に構成されている。 The reaction chamber 21 is a space formed by being surrounded by the heating element 23. A silicon carbide single crystal substrate 10 is arranged in reaction chamber 21. Reaction chamber 21 is configured to heat silicon carbide single crystal substrate 10. The maximum diameter of the silicon carbide single crystal substrate is 100 mm or more. The reaction chamber 21 is provided with a susceptor plate 30 that holds the silicon carbide single crystal substrate 10. The susceptor plate 30 is configured to be able to rotate around the rotation shaft 22.
　製造装置２００は、ガス導入口２７およびガス排気口２８をさらに有している。ガス排気口２８は、図示しない排気ポンプに接続されている。図１中の矢印は、ガスの流れを示している。ガスは、ガス導入口２７から反応室２１に導入され、ガス排気口２８から排気される。反応室２１内の圧力は、ガスの供給量と、ガスの排気量とのバランスによって調整される。 The manufacturing apparatus 200 further includes a gas introduction port 27 and a gas exhaust port 28. The gas exhaust port 28 is connected to an exhaust pump (not shown). The arrows in FIG. 1 indicate the gas flow. The gas is introduced into the reaction chamber 21 from the gas introduction port 27 and is exhausted from the gas exhaust port 28. The pressure in the reaction chamber 21 is adjusted by the balance between the gas supply amount and the gas exhaust amount.
　第１ガス供給部１は、炭素を含む第１ガスを供給可能に構成されている。第１ガス供給部１は、たとえば第１ガスが充填されたガスボンベである。第１ガスは、たとえばプロパン（Ｃ3Ｈ8）ガスである。第１ガスは、たとえばメタン（ＣＨ4）ガス、エタン（Ｃ2Ｈ6）ガス、アセチレン（Ｃ2Ｈ2）ガス等であってもよい。また、プロパンガスは、水素ガスで希釈されてもよい。たとえばプロパンの含有率が１０体積％以上５０体積％以下であってもよい。典型的にはプロパンが３０体積％、水素が７０体積％の希釈ガスが用いられてもよい。希釈されたプロパンは、加熱分解がより容易になるからである。 The 1st gas supply part 1 is comprised so that supply of the 1st gas containing carbon is possible. The first gas supply unit 1 is, for example, a gas cylinder filled with a first gas. The first gas is, for example, propane (C 3 H 8 ) gas. The first gas may be, for example, methane (CH 4 ) gas, ethane (C 2 H 6 ) gas, acetylene (C 2 H 2 ) gas, or the like. Propane gas may be diluted with hydrogen gas. For example, the content of propane may be 10% by volume or more and 50% by volume or less. Typically, a diluent gas of 30% by volume of propane and 70% by volume of hydrogen may be used. This is because diluted propane is more easily decomposed by heating.
　第２ガス供給部２は、珪素を含む第２ガスを供給可能に構成されている。第２ガス供給部２は、たとえば第２ガスが充填されたガスボンベである。第２ガスは、たとえばシラン（ＳｉＨ4）ガスである。第２ガスは、たとえば、ジシラン（Ｓｉ2Ｈ6）ガス、ジクロロシラン（ＳｉＨ2Ｃｌ2）ガス、トリクロロシラン（ＳｉＨＣｌ3）ガス、四塩化珪素（ＳｉＣｌ4）ガス等であってもよい。 The second gas supply unit 2 is configured to be able to supply a second gas containing silicon. The second gas supply unit 2 is, for example, a gas cylinder filled with the second gas. The second gas is, for example, silane (SiH 4) gas. The second gas may be, for example, disilane (Si 2 H 6 ) gas, dichlorosilane (SiH 2 Cl 2 ) gas, trichlorosilane (SiHCl 3 ) gas, silicon tetrachloride (SiCl 4 ) gas, or the like.
　第３ガス供給部３は、窒素を含む第３ガスを供給可能に構成されている。第３ガス供給部３は、たとえば第３ガスが充填されたガスボンベである。第３ガスは、Ｎ（窒素原子）を含むドーピングガスであり、たとえば窒素（Ｎ２）ガスおよびアンモニア（ＮＨ３）ガスの少なくともいずれかである。アンモニアガスは、三重結合を有する窒素ガスに比べて熱分解されやすい。アンモニアガスを用いることにより、キャリア濃度の面内均一性の向上が期待できる。 The 3rd gas supply part 3 is comprised so that supply of the 3rd gas containing nitrogen is possible. The third gas supply unit 3 is, for example, a gas cylinder filled with a third gas. The third gas is doping gas containing N (nitrogen atom), for example, nitrogen (N 2) gas and ammonia (NH 3) is at least one gas. Ammonia gas is more easily pyrolyzed than nitrogen gas having a triple bond. By using ammonia gas, improvement in the in-plane uniformity of the carrier concentration can be expected.
　混合部５０は、第１ガスと、第２ガスと、第３ガスとを混合可能に構成されている。具体的には、混合部５０は、第１ガスと、第２ガスと、第３ガスとが混合される配管であり得る。混合部５０は、反応室２１のガス導入口２７に通じている。第１ガス供給部１と、第２ガス供給部２と、第３ガス供給部３とは、混合部５０に繋がれている。 The mixing unit 50 is configured to be able to mix the first gas, the second gas, and the third gas. Specifically, the mixing unit 50 may be a pipe in which the first gas, the second gas, and the third gas are mixed. The mixing unit 50 communicates with the gas inlet 27 of the reaction chamber 21. The first gas supply unit 1, the second gas supply unit 2, and the third gas supply unit 3 are connected to the mixing unit 50.
　キャリアガス供給部４は、たとえば水素などのキャリアガスを供給可能に構成されている。キャリアガス供給部４は、たとえば水素が充填されたガスボンベである。キャリアガス供給部４は、配管５４で混合部５０に繋がれている。 The carrier gas supply unit 4 is configured to be able to supply a carrier gas such as hydrogen. The carrier gas supply unit 4 is a gas cylinder filled with hydrogen, for example. The carrier gas supply unit 4 is connected to the mixing unit 50 by a pipe 54.
　第１加熱分解部５は、第１温度で、第１ガスを加熱可能に構成されている。第１加熱分解部５は、たとえば抵抗加熱ヒータまたは誘導加熱ヒータにより第１ガスが流れる空間が加熱可能に構成されている部分である。第１加熱分解部５は、たとえば第１ガス供給部１と混合部５０との間にある。第１温度は、たとえば１２００℃以上１６００℃以下であり、好ましくは、１２５０℃以上１５５０℃以下であり、さらに好ましくは、１３００℃以上１５００℃以下である。第１ガス供給部１は、配管５１で第１加熱分解部５と繋がれている。第１加熱分解部５は、配管５５で混合部５０と繋がれている。配管５５は、接続部１５において混合部５０と接合されていてもよい。 The first thermal decomposition unit 5 is configured to be capable of heating the first gas at the first temperature. The 1st thermal decomposition part 5 is a part comprised so that the space where 1st gas flows with a resistance heater or an induction heater can be heated, for example. The 1st thermal decomposition part 5 exists between the 1st gas supply part 1 and the mixing part 50, for example. The first temperature is, for example, 1200 ° C. or higher and 1600 ° C. or lower, preferably 1250 ° C. or higher and 1550 ° C. or lower, and more preferably 1300 ° C. or higher and 1500 ° C. or lower. The first gas supply unit 1 is connected to the first thermal decomposition unit 5 by a pipe 51. The first thermal decomposition unit 5 is connected to the mixing unit 50 by a pipe 55. The pipe 55 may be joined to the mixing unit 50 at the connection unit 15.
　第２加熱分解部６は、第２温度で、第２ガスを加熱分解可能に構成されている。第２加熱分解部６は、たとえば抵抗加熱ヒータまたは誘導加熱ヒータにより第２ガスが流れる空間が加熱可能に構成されている部分である。第２加熱分解部６は、たとえば第２ガス供給部２と混合部５０との間にある。第２温度は、たとえば４００℃以上８００℃以下であり、好ましくは４５０℃以上７５０℃以下であり、さらに好ましくは５００℃以上７００℃以下である。第２温度は、第１温度より低くてもよい。第２ガス供給部２は、配管５２で第２加熱分解部６と繋がれている。第２加熱分解部６は、配管５６で混合部５０と繋がれている。配管５６は、接続部１６において混合部５０と接合されていてもよい。 The second thermal decomposition unit 6 is configured to be capable of thermally decomposing the second gas at the second temperature. The second thermal decomposition unit 6 is a part in which the space in which the second gas flows can be heated by, for example, a resistance heater or an induction heater. The 2nd thermal decomposition part 6 exists between the 2nd gas supply part 2 and the mixing part 50, for example. The second temperature is, for example, 400 ° C. or higher and 800 ° C. or lower, preferably 450 ° C. or higher and 750 ° C. or lower, and more preferably 500 ° C. or higher and 700 ° C. or lower. The second temperature may be lower than the first temperature. The second gas supply unit 2 is connected to the second thermal decomposition unit 6 through a pipe 52. The second thermal decomposition unit 6 is connected to the mixing unit 50 by a pipe 56. The pipe 56 may be joined to the mixing unit 50 at the connection unit 16.
　第３加熱分解部７は、第３温度で、第３ガスを加熱分解可能に構成されている。第３加熱分解部７は、たとえば抵抗加熱ヒータまたは誘導加熱ヒータにより第３ガスが流れる空間が加熱可能に構成されている部分である。第３加熱分解部７は、たとえば第３ガス供給部３と混合部５０との間にある。第３温度は、たとえば６００℃以上１０００℃以下であり、好ましくは６５０℃以上９５０℃以下であり、さらに好ましくは７００℃以上９００℃以下である。第３温度は、第１温度よりも低くてもよい。第３温度は、第２温度よりも高くてもよい。第３ガス供給部３は、配管５３で第３加熱分解部７と繋がれている。第３加熱分解部７は、配管５７で混合部５０と繋がれている。配管５７は、接続部１７において混合部５０と接合されていてもよい。 The third thermal decomposition unit 7 is configured to be able to thermally decompose the third gas at the third temperature. The 3rd thermal decomposition part 7 is a part comprised so that the space through which 3rd gas flows can be heated, for example with a resistance heater or an induction heater. The 3rd thermal decomposition part 7 exists between the 3rd gas supply part 3 and the mixing part 50, for example. The third temperature is, for example, 600 ° C. or higher and 1000 ° C. or lower, preferably 650 ° C. or higher and 950 ° C. or lower, and more preferably 700 ° C. or higher and 900 ° C. or lower. The third temperature may be lower than the first temperature. The third temperature may be higher than the second temperature. The third gas supply unit 3 is connected to the third thermal decomposition unit 7 by a pipe 53. The third thermal decomposition unit 7 is connected to the mixing unit 50 by a pipe 57. The pipe 57 may be joined to the mixing unit 50 at the connection unit 17.
　（第１変形例）
　図２に示されるように、製造装置２００は、第１加熱分解部５を有しているが、第２加熱分解部６および第３加熱分解部７を有していなくてもよい。第２ガス供給部２は、第２加熱分解部６を介することなく、配管５２で混合部５０に繋がれている。同様に、第３ガス供給部３は、第３加熱分解部７を介することなく、配管５３で混合部５０に接続されている。上記以外の構成は、本実施形態に係る製造装置２００の構成とほぼ同様であるため、同一または対応する要素には同一の符号を付し、それらについて同じ説明は繰り返さない。 (First modification)
As shown in FIG. 2, the manufacturing apparatus 200 includes the first thermal decomposition unit 5, but may not include the second thermal decomposition unit 6 and the third thermal decomposition unit 7. The second gas supply unit 2 is connected to the mixing unit 50 by a pipe 52 without passing through the second thermal decomposition unit 6. Similarly, the third gas supply unit 3 is connected to the mixing unit 50 through a pipe 53 without passing through the third thermal decomposition unit 7. Since the configuration other than the above is substantially the same as the configuration of the manufacturing apparatus 200 according to the present embodiment, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated.
　（第２変形例）
　図３に示されるように、製造装置２００は、第１加熱分解部５および第３加熱分解部７を有しているが、第２加熱分解部６を有していなくてもよい。第２ガス供給部２は、第２加熱分解部６を介することなく、配管５２で混合部５０に接続されている。上記以外の構成は、本実施形態に係る製造装置２００の構成とほぼ同様であるため、同一または対応する要素には同一の符号を付し、それらについて同じ説明は繰り返さない。 (Second modification)
As shown in FIG. 3, the manufacturing apparatus 200 includes the first thermal decomposition unit 5 and the third thermal decomposition unit 7, but may not include the second thermal decomposition unit 6. The second gas supply unit 2 is connected to the mixing unit 50 through a pipe 52 without going through the second thermal decomposition unit 6. Since the configuration other than the above is substantially the same as the configuration of the manufacturing apparatus 200 according to the present embodiment, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated.
　（第３変形例）
　図４に示されるように、製造装置２００は、第１加熱分解部５および第２加熱分解部６を有しているが、第３加熱分解部７を有していなくてもよい。第３ガス供給部３は、第３加熱分解部７を介することなく、配管５３で混合部５０に接続されている。上記以外の構成は、本実施形態に係る製造装置２００の構成とほぼ同様であるため、同一または対応する要素には同一の符号を付し、それらについて同じ説明は繰り返さない。 (Third Modification)
As shown in FIG. 4, the manufacturing apparatus 200 includes the first thermal decomposition unit 5 and the second thermal decomposition unit 6, but may not include the third thermal decomposition unit 7. The third gas supply unit 3 is connected to the mixing unit 50 through a pipe 53 without passing through the third thermal decomposition unit 7. Since the configuration other than the above is substantially the same as the configuration of the manufacturing apparatus 200 according to the present embodiment, the same or corresponding elements are denoted by the same reference numerals, and the same description is not repeated.
　（炭化珪素エピタキシャル基板の製造方法）
　次に、本実施形態に係る炭化珪素エピタキシャル基板の製造方法について説明する。 (Method for producing silicon carbide epitaxial substrate)
Next, a method for manufacturing the silicon carbide epitaxial substrate according to this embodiment will be described.
　まず、炭化珪素単結晶基板を配置する工程（Ｓ１：図５）が実施される。たとえば昇華法により、ポリタイプ６Ｈの炭化珪素単結晶が製造される。次に、たとえばワイヤーソーによって、炭化珪素単結晶をスライスすることにより、炭化珪素単結晶基板１０が準備される（図６参照）。炭化珪素単結晶基板１０は、第１主面４１と、第１主面４１と反対側の第２主面４２とを有する。当該炭化珪素単結晶のポリタイプは、たとえば４Ｈ－ＳｉＣである。４Ｈ－ＳｉＣは、電子移動度、絶縁破壊電界強度等において他のポリタイプより優れている。炭化珪素単結晶基板１０は、たとえば窒素などのｎ型不純物を含んでいる。炭化珪素単結晶基板１０の導電型は、たとえばｎ型である。 First, a step of placing a silicon carbide single crystal substrate (S1: FIG. 5) is performed. For example, a silicon carbide single crystal of polytype 6H is manufactured by a sublimation method. Next, silicon carbide single crystal substrate 10 is prepared by slicing the silicon carbide single crystal with, for example, a wire saw (see FIG. 6). Silicon carbide single crystal substrate 10 has a first main surface 41 and a second main surface 42 opposite to the first main surface 41. The polytype of the silicon carbide single crystal is, for example, 4H—SiC. 4H—SiC is superior to other polytypes in terms of electron mobility, dielectric breakdown field strength, and the like. Silicon carbide single crystal substrate 10 contains an n-type impurity such as nitrogen, for example. Silicon carbide single crystal substrate 10 has an n-type conductivity, for example.
　第１主面４１は、たとえば｛０００１｝面もしくは｛０００１｝面から８°以下の角度だけ傾斜した面である。具体的には、第１主面４１は、（０００１）面もしくは（０００１）面から８°以下の角度だけ傾斜した面であってもよいし、（０００－１）面もしくは（０００－１）面から８°以下の角度だけ傾斜した面であってもよい。第１主面４１が｛０００１｝面から傾斜している場合、第１主面４１の法線の傾斜方向は、たとえば＜１１－２０＞方向である。｛０００１｝面からの傾斜角（オフ角）は、１°以上であってもよいし、２°以上であってもよい。オフ角は、７°以下であってもよいし、６°以下であってもよいし、４°以下であってもよい。 The first main surface 41 is, for example, a surface inclined by an angle of 8 ° or less from the {0001} plane or the {0001} plane. Specifically, the first principal surface 41 may be a (0001) plane or a plane inclined by an angle of 8 ° or less from the (0001) plane, or a (000-1) plane or (000-1). The surface may be inclined by an angle of 8 ° or less from the surface. When the first main surface 41 is inclined from the {0001} plane, the inclination direction of the normal line of the first main surface 41 is, for example, the <11-20> direction. The inclination angle (off angle) from the {0001} plane may be 1 ° or more, or 2 ° or more. The off-angle may be 7 ° or less, 6 ° or less, or 4 ° or less.
　炭化珪素単結晶基板１０の第１主面４１の最大径（直径）は、１００ｍｍ以上である。直径は１５０ｍｍ以上でもよいし、２００ｍｍ以上でもよいし、２５０ｍｍ以上でもよい。直径の上限は特に限定されないが、直径の上限はたとえば３００ｍｍであってもよい。 The maximum diameter (diameter) of first main surface 41 of silicon carbide single crystal substrate 10 is 100 mm or more. The diameter may be 150 mm or more, 200 mm or more, or 250 mm or more. The upper limit of the diameter is not particularly limited, but the upper limit of the diameter may be 300 mm, for example.
　次に、炭化珪素単結晶基板１０が反応室２１内に配置される。図１に示されるように、炭化珪素単結晶基板１０は、サセプタプレート３０の凹部内に配置される。次に、製造装置２００を用いて、炭化珪素単結晶基板１０上に炭化珪素層２０がエピタキシャル成長によって形成される。 Next, the silicon carbide single crystal substrate 10 is placed in the reaction chamber 21. As shown in FIG. 1, silicon carbide single crystal substrate 10 is disposed in a recess of susceptor plate 30. Next, silicon carbide layer 20 is formed by epitaxial growth on silicon carbide single crystal substrate 10 using manufacturing apparatus 200.
　たとえば反応室２１の圧力が大気圧から１×１０-6Ｐａ程度に低減された後、炭化珪素単結晶基板１０の昇温が開始される。昇温の途中において、キャリアガス供給部４からキャリアガスである水素（Ｈ2）ガスが配管５４を通じて混合部５０に供給される。混合部５０に供給されたキャリアガスは反応室２１に導入される。水素ガスの流量は、たとえばＭＦＣ(Ｍａｓｓ　Ｆｌｏｗ　Ｃｏｎｔｒｏｌｌｅｒ)により調整される。この操作により、たとえば反応室２１内の残留窒素の低減が期待される。次に、誘導加熱コイル２６に交流電圧を印加することにより発熱体２３が加熱される。 For example, after the pressure in the reaction chamber 21 is reduced from atmospheric pressure to about 1 × 10 −6 Pa, the temperature rise of the silicon carbide single crystal substrate 10 is started. During the temperature increase, hydrogen (H 2 ) gas, which is a carrier gas, is supplied from the carrier gas supply unit 4 to the mixing unit 50 through the pipe 54. The carrier gas supplied to the mixing unit 50 is introduced into the reaction chamber 21. The flow rate of the hydrogen gas is adjusted by, for example, MFC (Mass Flow Controller). By this operation, for example, reduction of residual nitrogen in the reaction chamber 21 is expected. Next, the heating element 23 is heated by applying an AC voltage to the induction heating coil 26.
　次に、第１ガス供給部１から第１ガスが、配管５１を通して第１加熱分解部５に供給される。第１加熱分解部５において、炭素を含む第１ガスが加熱分解される。第１ガスは、第１温度で加熱分解される。加熱分解された第１ガスは、配管５５を通して混合部５０に送られる。図１において、矢印１１は、加熱分解される前の第１ガスの流れを示し、矢印３１は、加熱分解された後の第１ガスの流れを示している。第１ガスは、たとえばプロパン（Ｃ3Ｈ8）ガスである。第１ガスは、たとえばメタン（ＣＨ4）ガス、エタン（Ｃ2Ｈ6）ガス、アセチレン（Ｃ2Ｈ2）ガス等であってもよい。第１温度は、たとえば１２００℃以上１６００℃以下であり、好ましくは、１２５０℃以上１５５０℃以下であり、さらに好ましくは、１３００℃以上１５００℃以下である。 Next, the first gas is supplied from the first gas supply unit 1 to the first thermal decomposition unit 5 through the pipe 51. In the 1st thermal decomposition part 5, the 1st gas containing carbon is thermally decomposed. The first gas is thermally decomposed at the first temperature. The thermally decomposed first gas is sent to the mixing unit 50 through the pipe 55. In FIG. 1, an arrow 11 indicates the flow of the first gas before being thermally decomposed, and an arrow 31 indicates the flow of the first gas after being thermally decomposed. The first gas is, for example, propane (C 3 H 8 ) gas. The first gas may be, for example, methane (CH 4 ) gas, ethane (C 2 H 6 ) gas, acetylene (C 2 H 2 ) gas, or the like. The first temperature is, for example, 1200 ° C. or higher and 1600 ° C. or lower, preferably 1250 ° C. or higher and 1550 ° C. or lower, and more preferably 1300 ° C. or higher and 1500 ° C. or lower.
　同様に、第２ガス供給部２から第２ガスが、配管５２を通して第２加熱分解部６に供給される。第２加熱分解部６において、珪素を含む第２ガスが加熱分解される。第２ガスは、第２温度で加熱分解される。加熱分解された第２ガスは、配管５６を通して混合部５０に送られる。図１において、矢印１２は、加熱分解される前の第２ガスの流れを示し、矢印３２は、加熱分解された後の第２ガスの流れを示している。第２ガスは、たとえばシラン（ＳｉＨ4）ガスである。第２ガスは、たとえば、ジシラン（Ｓｉ2Ｈ6）ガス、ジクロロシラン（ＳｉＨ2Ｃｌ2）ガス、トリクロロシラン（ＳｉＨＣｌ3）ガス、四塩化珪素（ＳｉＣｌ4）ガス等であってもよい。第２温度は、たとえば４００℃以上８００℃以下であり、好ましくは４５０℃以上７５０℃以下であり、さらに好ましくは５００℃以上７００℃以下である。第２温度は、第１温度より低くてもよい。 Similarly, the second gas is supplied from the second gas supply unit 2 to the second thermal decomposition unit 6 through the pipe 52. In the second thermal decomposition unit 6, the second gas containing silicon is thermally decomposed. The second gas is thermally decomposed at the second temperature. The thermally decomposed second gas is sent to the mixing unit 50 through the pipe 56. In FIG. 1, an arrow 12 indicates the flow of the second gas before being thermally decomposed, and an arrow 32 indicates the flow of the second gas after being thermally decomposed. The second gas is, for example, silane (SiH 4 ) gas. The second gas may be, for example, disilane (Si 2 H 6 ) gas, dichlorosilane (SiH 2 Cl 2 ) gas, trichlorosilane (SiHCl 3 ) gas, silicon tetrachloride (SiCl 4 ) gas, or the like. The second temperature is, for example, 400 ° C. or higher and 800 ° C. or lower, preferably 450 ° C. or higher and 750 ° C. or lower, and more preferably 500 ° C. or higher and 700 ° C. or lower. The second temperature may be lower than the first temperature.
　同様に、第３ガス供給部３から第３ガスが、配管５３を通して第３加熱分解部７に供給される。第３加熱分解部７において、窒素を含む第３ガスが加熱分解される。第３ガスは、第３温度で加熱分解される。加熱分解された第３ガスは、配管５７を通して混合部５０に送られる。図１において、矢印１３は、加熱分解される前の第３ガスの流れを示し、矢印３３は、加熱分解された後の第３ガスの流れを示している。第３ガスは、たとえば窒素ガスおよびアンモニアガスの少なくともいずれかである。第３温度は、たとえば６００℃以上１０００℃以下であり、好ましくは６５０℃以上９５０℃以下であり、さらに好ましくは７００℃以上９００℃以下である。第３温度は、第１温度よりも低くてもよい。第３温度は、第２温度よりも高くてもよい。 Similarly, the third gas is supplied from the third gas supply unit 3 to the third thermal decomposition unit 7 through the pipe 53. In the 3rd thermal decomposition part 7, the 3rd gas containing nitrogen is thermally decomposed. The third gas is thermally decomposed at the third temperature. The thermally decomposed third gas is sent to the mixing unit 50 through the pipe 57. In FIG. 1, an arrow 13 indicates the flow of the third gas before being thermally decomposed, and an arrow 33 indicates the flow of the third gas after being thermally decomposed. The third gas is, for example, at least one of nitrogen gas and ammonia gas. The third temperature is, for example, 600 ° C. or higher and 1000 ° C. or lower, preferably 650 ° C. or higher and 950 ° C. or lower, and more preferably 700 ° C. or higher and 900 ° C. or lower. The third temperature may be lower than the first temperature. The third temperature may be higher than the second temperature.
　次に、混合ガスを生成する工程（Ｓ２：図５）が実施される。たとえば混合部５０において、炭素を含む第１ガスと、珪素を含む第２ガスと、窒素を含む第３ガスと、キャリアガスとが混合されことによって混合ガスが生成される。第１ガスは、加熱分解された状態である。第２ガスは、加熱分解された状態または加熱分解されていない状態である。第３ガスは、加熱分解された状態または加熱分解されていない状態である。たとえば、プロパンが加熱分解された第１ガスと、シランが加熱分解された第２ガスと、アンモニアが加熱分解された第３ガスと、水素ガスとが混合される。 Next, a step of generating a mixed gas (S2: FIG. 5) is performed. For example, in the mixing unit 50, a mixed gas is generated by mixing a first gas containing carbon, a second gas containing silicon, a third gas containing nitrogen, and a carrier gas. The first gas is in a thermally decomposed state. The second gas is in a state of being thermally decomposed or not being thermally decomposed. The third gas is in a state of being thermally decomposed or not being thermally decomposed. For example, a first gas obtained by thermally decomposing propane, a second gas obtained by thermally decomposing silane, a third gas obtained by thermally decomposing ammonia, and hydrogen gas are mixed.
　代替的に、図２に示されるように、加熱分解された第１ガスと、加熱分解されていない第２ガスと、加熱分解されていない第３ガスと、キャリアガスとが混合されてもよい。第１ガスは加熱分解された状態であり、第２ガスは加熱分解されていない状態であり、かつ第３ガスは加熱分解されていない状態である。代替的に、図３に示されるように、加熱分解された第１ガスと、加熱分解されていない第２ガスと、加熱分解された第３ガスと、キャリアガスとが混合されてもよい。第１ガスは加熱分解された状態であり、第２ガスは加熱分解されていない状態であり、かつ第３ガスは加熱分解された状態である。代替的に、図４に示されるように、加熱分解された第１ガスと、加熱分解された第２ガスと、加熱分解されていない第３ガスと、キャリアガスとが混合されてもよい。第１ガスは加熱分解された状態であり、第２ガスは加熱分解された状態であり、かつ第３ガスは加熱分解されていない状態である。 Alternatively, as shown in FIG. 2, a first gas that has been pyrolyzed, a second gas that has not been pyrolyzed, a third gas that has not been pyrolyzed, and a carrier gas may be mixed. . The first gas is in a thermally decomposed state, the second gas is not thermally decomposed, and the third gas is not thermally decomposed. Alternatively, as shown in FIG. 3, the first gas that has been thermally decomposed, the second gas that has not been thermally decomposed, the third gas that has been thermally decomposed, and the carrier gas may be mixed. The first gas is in a state of being thermally decomposed, the second gas is in a state of not being thermally decomposed, and the third gas is in a state of being thermally decomposed. Alternatively, as shown in FIG. 4, a first gas that has been thermally decomposed, a second gas that has been thermally decomposed, a third gas that has not been thermally decomposed, and a carrier gas may be mixed. The first gas is in a thermally decomposed state, the second gas is in a thermally decomposed state, and the third gas is in a state in which it is not thermally decomposed.
　次に、混合ガスを反応室に導入する工程（Ｓ３：図５）が実施される。第１ガス、第２ガスおよび第３ガスが混合された混合ガスが反応室２１に導入される。混合ガスには、キャリアガスが含まれてもよい。具体的には、反応室２１内の温度をたとえば１６００℃程度とした状態で、混合ガスが反応室２１に導入される。混合ガスのＣ／Ｓｉ比は、たとえば０．９であってもよい。混合ガスが反応室２１に導入されている間、炭化珪素単結晶基板１０は回転軸２２の周りを回転していてもよい。反応室２１内で混合ガスが加熱されることにより、炭化珪素単結晶基板１０上に炭化珪素層２０が形成される（Ｓ４：図５）。炭化珪素層２０は、エピタキシャル層である。炭化珪素層２０は、炭化珪素単結晶基板１０に接する第４主面４４と、第４主面４４と反対側の第３主面４３とを有する。以上により、炭化珪素単結晶基板１０と、炭化珪素層２０とを含む炭化珪素エピタキシャル基板１００（図７参照）が製造される。 Next, the step of introducing the mixed gas into the reaction chamber (S3: FIG. 5) is performed. A mixed gas in which the first gas, the second gas, and the third gas are mixed is introduced into the reaction chamber 21. The mixed gas may include a carrier gas. Specifically, the mixed gas is introduced into the reaction chamber 21 in a state where the temperature in the reaction chamber 21 is about 1600 ° C., for example. The C / Si ratio of the mixed gas may be 0.9, for example. While the mixed gas is introduced into the reaction chamber 21, the silicon carbide single crystal substrate 10 may rotate around the rotation shaft 22. By heating the mixed gas in reaction chamber 21, silicon carbide layer 20 is formed on silicon carbide single crystal substrate 10 (S4: FIG. 5). Silicon carbide layer 20 is an epitaxial layer. Silicon carbide layer 20 has a fourth main surface 44 in contact with silicon carbide single crystal substrate 10 and a third main surface 43 opposite to fourth main surface 44. Thus, silicon carbide epitaxial substrate 100 (see FIG. 7) including silicon carbide single crystal substrate 10 and silicon carbide layer 20 is manufactured.
　上記方法で測定された炭化珪素エピタキシャル基板１００によれば、予め炭素を含む第１ガスが加熱分解されているため、第３主面４３と平行な方向における炭化珪素層２０中のキャリア濃度の面内均一性の向上が期待できる。直径が１５０ｍｍの炭化珪素エピタキシャル基板１００の場合、キャリア濃度の面内均一性は、たとえば３％以内である。キャリア濃度は、たとえばＣ－Ｖ法により測定することができる。キャリア濃度の測定箇所は、たとえば計２９カ所である。各々の測定箇所は、第３主面４３の中心を通る十字上にほぼ等間隔で配置されている。キャリア濃度の面内均一性は、たとえば全測定箇所におけるキャリア濃度の標準偏差を、キャリア濃度の平均値で除した値を百分率表記した値である。 According to silicon carbide epitaxial substrate 100 measured by the above method, since the first gas containing carbon is thermally decomposed in advance, the surface of the carrier concentration in silicon carbide layer 20 in the direction parallel to third main surface 43. Improvement in internal uniformity can be expected. In the case of silicon carbide epitaxial substrate 100 having a diameter of 150 mm, the in-plane uniformity of the carrier concentration is, for example, within 3%. The carrier concentration can be measured by, for example, the CV method. There are a total of 29 locations where the carrier concentration is measured, for example. Each measurement point is arranged at substantially equal intervals on a cross passing through the center of the third main surface 43. The in-plane uniformity of the carrier concentration is, for example, a value expressed as a percentage obtained by dividing the standard deviation of the carrier concentration at all measurement locations by the average value of the carrier concentration.
　（炭化珪素半導体装置の製造方法）
　次に、本実施形態に係る炭化珪素半導体装置３００の製造方法について説明する。 (Method for manufacturing silicon carbide semiconductor device)
Next, a method for manufacturing the silicon carbide semiconductor device 300 according to this embodiment will be described.
　本実施形態に係る炭化珪素半導体装置の製造方法は、エピタキシャル基板準備工程（Ｓ１０：図８）と、基板加工工程（Ｓ２０：図８）とを主に有する。 The method for manufacturing a silicon carbide semiconductor device according to the present embodiment mainly includes an epitaxial substrate preparation step (S10: FIG. 8) and a substrate processing step (S20: FIG. 8).
　まず、エピタキシャル基板準備工程（Ｓ１０：図８）が実施される。具体的には、前述した炭化珪素エピタキシャル基板の製造方法によって、炭化珪素エピタキシャル基板１００が準備される（図７参照）。 First, an epitaxial substrate preparation step (S10: FIG. 8) is performed. Specifically, silicon carbide epitaxial substrate 100 is prepared by the above-described method for manufacturing a silicon carbide epitaxial substrate (see FIG. 7).
　次に、基板加工工程（Ｓ２０：図８）が実施される。具体的には、炭化珪素エピタキシャル基板を加工することにより、炭化珪素半導体装置が製造される。「加工」には、たとえば、イオン注入、熱処理、エッチング、酸化膜形成、電極形成、ダイシング等の各種加工が含まれる。すなわち基板加工ステップは、イオン注入、熱処理、エッチング、酸化膜形成、電極形成およびダイシングのうち、少なくともいずれかの加工を含むものであってもよい。 Next, a substrate processing step (S20: FIG. 8) is performed. Specifically, a silicon carbide semiconductor device is manufactured by processing a silicon carbide epitaxial substrate. “Processing” includes, for example, various processes such as ion implantation, heat treatment, etching, oxide film formation, electrode formation, and dicing. That is, the substrate processing step may include at least one of ion implantation, heat treatment, etching, oxide film formation, electrode formation, and dicing.
　以下では、炭化珪素半導体装置の一例としてのＭＯＳＦＥＴ（Ｍｅｔａｌ　Ｏｘｉｄｅ　Ｓｅｍｉｃｏｎｄｕｃｔｏｒ　Ｆｉｅｌｄ　Ｅｆｆｅｃｔ　Ｔｒａｎｓｉｓｔｏｒ）の製造方法を説明する。基板加工工程（Ｓ２０：図８）は、イオン注入工程（Ｓ２１：図８）、酸化膜形成工程（Ｓ２２：図８）、電極形成工程（Ｓ２３：図８）およびダイシング工程（Ｓ２４：図８）を含む。 Hereinafter, a method for manufacturing a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) as an example of a silicon carbide semiconductor device will be described. The substrate processing step (S20: FIG. 8) includes an ion implantation step (S21: FIG. 8), an oxide film formation step (S22: FIG. 8), an electrode formation step (S23: FIG. 8), and a dicing step (S24: FIG. 8). including.
　まず、イオン注入工程（Ｓ２１：図８）が実施される。開口部を有するマスク（図示せず）が形成された第３主面４３に対して、たとえばアルミニウム（Ａｌ）等のｐ型不純物が注入される。これにより、ｐ型の導電型を有するボディ領域１３２が形成される。次に、ボディ領域１３２内の所定位置に、たとえばリン（Ｐ）等のｎ型不純物が注入される。これにより、ｎ型の導電型を有するソース領域１３３が形成される。次に、アルミニウム等のｐ型不純物がソース領域１３３内の所定位置に注入される。これにより、ｐ型の導電型を有するコンタクト領域１３４が形成される（図９参照）。 First, an ion implantation step (S21: FIG. 8) is performed. A p-type impurity such as aluminum (Al) is implanted into the third main surface 43 on which a mask (not shown) having an opening is formed. Thereby, body region 132 having p-type conductivity is formed. Next, an n-type impurity such as phosphorus (P) is implanted into a predetermined position in body region 132. Thereby, a source region 133 having n-type conductivity is formed. Next, a p-type impurity such as aluminum is implanted into a predetermined position in the source region 133. As a result, a contact region 134 having a p-type conductivity is formed (see FIG. 9).
　炭化珪素層２０において、ボディ領域１３２、ソース領域１３３およびコンタクト領域１３４以外の部分は、ドリフト領域１３１となる。ソース領域１３３は、ボディ領域１３２によってドリフト領域１３１から隔てられている。イオン注入は、炭化珪素エピタキシャル基板１００を３００℃以上６００℃以下程度に加熱して行われてもよい。イオン注入の後、炭化珪素エピタキシャル基板１００に対して活性化アニールが行われる。活性化アニールにより、炭化珪素層２０に注入された不純物が活性化し、各領域においてキャリアが生成される。活性化アニールの雰囲気は、たとえばアルゴン（Ａｒ）雰囲気でもよい。活性化アニールの温度は、たとえば１８００℃程度でもよい。活性化アニールの時間は、たとえば３０分程度でもよい。 In silicon carbide layer 20, portions other than body region 132, source region 133, and contact region 134 serve as drift region 131. Source region 133 is separated from drift region 131 by body region 132. Ion implantation may be performed by heating silicon carbide epitaxial substrate 100 to about 300 ° C. or more and 600 ° C. or less. After the ion implantation, activation annealing is performed on silicon carbide epitaxial substrate 100. By the activation annealing, the impurities injected into the silicon carbide layer 20 are activated, and carriers are generated in each region. The atmosphere of activation annealing may be, for example, an argon (Ar) atmosphere. The activation annealing temperature may be about 1800 ° C., for example. The activation annealing time may be about 30 minutes, for example.
　次に、酸化膜形成工程（Ｓ２２：図８）が実施される。たとえば炭化珪素エピタキシャル基板１００が酸素を含む雰囲気中において加熱されることにより、第３主面４３上に酸化膜１３６が形成される（図１０参照）。酸化膜１３６は、たとえば二酸化珪素（ＳｉＯ2）等から構成される。酸化膜１３６は、ゲート絶縁膜として機能する。熱酸化処理の温度は、たとえば１３００℃程度でもよい。熱酸化処理の時間は、たとえば３０分程度でもよい。 Next, an oxide film forming step (S22: FIG. 8) is performed. For example, silicon carbide epitaxial substrate 100 is heated in an atmosphere containing oxygen, whereby oxide film 136 is formed on third main surface 43 (see FIG. 10). Oxide film 136 is made of, for example, silicon dioxide (SiO 2 ). The oxide film 136 functions as a gate insulating film. The temperature of the thermal oxidation treatment may be about 1300 ° C., for example. The thermal oxidation treatment time may be about 30 minutes, for example.
　酸化膜１３６が形成された後、さらに窒素雰囲気中で熱処理が行なわれてもよい。たとえば、一酸化窒素（ＮＯ）、亜酸化窒素（Ｎ2Ｏ）等の雰囲気中、１１００℃程度で１時間程度、熱処理が実施されてもよい。さらにその後、アルゴン雰囲気中で熱処理が行なわれてもよい。たとえば、アルゴン雰囲気中、１１００～１５００℃程度で、１時間程度、熱処理が行われてもよい。 After the oxide film 136 is formed, heat treatment may be performed in a nitrogen atmosphere. For example, the heat treatment may be performed at about 1100 ° C. for about 1 hour in an atmosphere such as nitric oxide (NO) or nitrous oxide (N 2 O). Thereafter, heat treatment may be performed in an argon atmosphere. For example, the heat treatment may be performed in an argon atmosphere at about 1100 to 1500 ° C. for about 1 hour.
　次に、電極形成工程（Ｓ２３：図８）が実施される。第１電極１４１は、酸化膜１３６上に形成される。第１電極１４１は、ゲート電極として機能する。第１電極１４１は、たとえばＣＶＤ法により形成される。第１電極１４１は、たとえば不純物を含有し導電性を有するポリシリコン等から構成される。第１電極１４１は、ソース領域１３３およびボディ領域１３２に対面する位置に形成される。 Next, an electrode formation step (S23: FIG. 8) is performed. The first electrode 141 is formed on the oxide film 136. The first electrode 141 functions as a gate electrode. The first electrode 141 is formed by, for example, a CVD method. The first electrode 141 is made of, for example, polysilicon containing impurities and having conductivity. The first electrode 141 is formed at a position facing the source region 133 and the body region 132.
　次に、第１電極１４１を覆う層間絶縁膜１３７が形成される。層間絶縁膜１３７は、たとえばＣＶＤ法により形成される。層間絶縁膜１３７は、たとえば二酸化珪素等から構成される。層間絶縁膜１３７は、第１電極１４１と酸化膜１３６とに接するように形成される。次に、所定位置の酸化膜１３６および層間絶縁膜１３７がエッチングによって除去される。これにより、ソース領域１３３およびコンタクト領域１３４が、酸化膜１３６から露出する。 Next, an interlayer insulating film 137 covering the first electrode 141 is formed. Interlayer insulating film 137 is formed by, for example, a CVD method. Interlayer insulating film 137 is made of, for example, silicon dioxide. The interlayer insulating film 137 is formed so as to be in contact with the first electrode 141 and the oxide film 136. Next, the oxide film 136 and the interlayer insulating film 137 at predetermined positions are removed by etching. As a result, the source region 133 and the contact region 134 are exposed from the oxide film 136.
　たとえばスパッタリング法により当該露出部に第２電極１４２が形成される。第２電極１４２はソース電極として機能する。第２電極１４２は、たとえばチタン、アルミニウムおよびシリコン等から構成される。第２電極１４２が形成された後、第２電極１４２と炭化珪素エピタキシャル基板１００が、たとえば９００～１１００℃程度の温度で加熱される。これにより、第２電極１４２と炭化珪素エピタキシャル基板１００とがオーミック接触するようになる。次に、第２電極１４２に接するように、配線層１３８が形成される。配線層１３８は、たとえばアルミニウムを含む材料から構成される。 For example, the second electrode 142 is formed on the exposed portion by sputtering. The second electrode 142 functions as a source electrode. Second electrode 142 is made of, for example, titanium, aluminum, silicon, or the like. After formation of second electrode 142, second electrode 142 and silicon carbide epitaxial substrate 100 are heated at a temperature of about 900 to 1100 ° C., for example. Thereby, second electrode 142 and silicon carbide epitaxial substrate 100 come into ohmic contact. Next, the wiring layer 138 is formed so as to be in contact with the second electrode 142. The wiring layer 138 is made of a material containing aluminum, for example.
　次に、第２主面４２に第３電極１４３が形成される。第３電極１４３は、ドレイン電極として機能する。第３電極１４３は、たとえばニッケルおよびシリコンを含む合金（たとえばＮｉＳｉ等）から構成される。 Next, the third electrode 143 is formed on the second main surface 42. The third electrode 143 functions as a drain electrode. Third electrode 143 is made of, for example, an alloy containing nickel and silicon (eg, NiSi).
　次に、ダイシング工程（Ｓ２４：図８）が実施される。たとえば炭化珪素エピタキシャル基板１００がダイシングラインに沿ってダイシングされることにより、炭化珪素エピタキシャル基板１００が複数の半導体チップに分割される。以上より、炭化珪素半導体装置３００が製造される（図１１参照）。 Next, a dicing step (S24: FIG. 8) is performed. For example, silicon carbide epitaxial substrate 100 is diced along a dicing line, whereby silicon carbide epitaxial substrate 100 is divided into a plurality of semiconductor chips. Thus, silicon carbide semiconductor device 300 is manufactured (see FIG. 11).
　上記において、ＭＯＳＦＥＴを例示して、本開示に係る炭化珪素半導体装置の製造方法を説明したが、本開示に係る製造方法はこれに限定されない。本開示に係る製造方法は、たとえばＩＧＢＴ（Ｉｎｓｕｌａｔｅｄ　Ｇａｔｅ　Ｂｉｐｏｌａｒ　Ｔｒａｎｓｉｓｔｏｒ）、ＳＢＤ（Ｓｃｈｏｔｔｋｙ　Ｂａｒｒｉｅｒ　Ｄｉｏｄｅ）、サイリスタ、ＧＴＯ（Ｇａｔｅ　Ｔｕｒｎ　Ｏｆｆ　ｔｈｙｒｉｓｔｏｒ）、ＰｉＮダイオード等の各種炭化珪素半導体装置に適用可能である。 In the above, the method for manufacturing the silicon carbide semiconductor device according to the present disclosure has been described by exemplifying the MOSFET, but the manufacturing method according to the present disclosure is not limited to this. The manufacturing method according to the present disclosure is applicable to various silicon carbide semiconductor devices such as IGBT (Insulated Gate Bipolar Transistor), SBD (Schottky Barrier Diode), thyristor, GTO (Gate Turn Off thyristor), and PiN diode.
　今回開示された実施形態はすべての点で例示であって、制限的なものではないと考えられるべきである。本発明の範囲は上記した実施形態ではなく請求の範囲によって示され、請求の範囲と均等の意味、および範囲内でのすべての変更が含まれることが意図される。 It should be considered that the embodiment disclosed this time is illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.
　１　第１ガス供給部、２　第２ガス供給部、３　第３ガス供給部、４　キャリアガス供給部、５　第１加熱分解部、６　第２加熱分解部、７　第３加熱分解部、１０　炭化珪素単結晶基板、１５，１６，１７　接続部、２０　炭化珪素層、２１　反応室、２２　回転軸、２３　発熱体、２４　石英管、２５　断熱材、２６　誘導加熱コイル、２７　ガス導入口、２８　ガス排気口、３０　サセプタプレート、４１　第１主面、４２　第２主面、４３　第３主面、４４　第４主面、５０　混合部、５１，５２，５３，５４，５５，５６，５７　配管、１００　炭化珪素エピタキシャル基板、１３１　ドリフト領域、１３２　ボディ領域、１３３　ソース領域、１３４　コンタクト領域、１３６　酸化膜、１３７　層間絶縁膜、１３８　配線層、１４１　第１電極、１４２　第２電極、１４３　第３電極、２００　製造装置、３００　炭化珪素半導体装置。 1 1st gas supply unit 2 2nd gas supply unit 3 3rd gas supply unit 4 4 carrier gas supply unit 5 1st thermal decomposition unit 6 2nd thermal decomposition unit 7 3rd thermal decomposition unit 10 carbonization Silicon single crystal substrate, 15, 16, 17 connection part, 20 silicon carbide layer, 21 reaction chamber, 22 rotating shaft, 23 heating element, 24 quartz tube, 25 heat insulating material, 26 induction heating coil, 27 gas inlet, 28 gas Exhaust port, 30 susceptor plate, 41 first main surface, 42 second main surface, 43 third main surface, 44 fourth main surface, 50 mixing section, 51, 52, 53, 54, 55, 56, 57 piping, 100 silicon carbide epitaxial substrate, 131 drift region, 132 body region, 133 source region, 134 contact region, 136 oxide film, 137 interlayer insulating film, 138 wiring layer 141 first electrode 142 second electrode, 143 third electrode, 200 manufacturing apparatus, 300 silicon carbide semiconductor device.

Claims (17)

  1. 　反応室内に、直径１００ｍｍ以上の炭化珪素単結晶基板を配置する工程と、
    　炭素を含み加熱分解された状態の第１ガスと、珪素を含む第２ガスと、窒素を含む第３ガスとを混合することによって混合ガスを生成する工程と、
    　前記混合ガスを前記反応室内に導入する工程と、
    　前記反応室内で前記混合ガスを加熱することにより、前記炭化珪素単結晶基板上に炭化珪素層を形成する工程と、を備える、炭化珪素エピタキシャル基板の製造方法。     Disposing a silicon carbide single crystal substrate having a diameter of 100 mm or more in the reaction chamber;
    Generating a mixed gas by mixing a first gas containing carbon and thermally decomposed, a second gas containing silicon, and a third gas containing nitrogen;
    Introducing the mixed gas into the reaction chamber;
    Forming a silicon carbide layer on the silicon carbide single crystal substrate by heating the mixed gas in the reaction chamber.
  2. 　前記混合ガスを生成する工程において、前記第２ガスは加熱分解された状態である、請求項１に記載の炭化珪素エピタキシャル基板の製造方法。 The method for manufacturing a silicon carbide epitaxial substrate according to claim 1, wherein, in the step of generating the mixed gas, the second gas is thermally decomposed.
  3. 　前記混合ガスを生成する工程において、前記第３ガスは加熱分解された状態である、請求項１に記載の炭化珪素エピタキシャル基板の製造方法。 The method for manufacturing a silicon carbide epitaxial substrate according to claim 1, wherein, in the step of generating the mixed gas, the third gas is in a thermally decomposed state.
  4. 　前記混合ガスを生成する工程において、前記第３ガスは加熱分解された状態である、請求項２に記載の炭化珪素エピタキシャル基板の製造方法。 The method for producing a silicon carbide epitaxial substrate according to claim 2, wherein, in the step of generating the mixed gas, the third gas is in a thermally decomposed state.
  5. 　前記第１ガスはＣ３Ｈ８を含み、前記第１ガスは１２００℃以上１６００℃以下の温度で加熱分解された状態である、請求項１～請求項４のいずれか１項に記載の炭化珪素エピタキシャル基板の製造方法。 The carbonization according to any one of claims 1 to 4, wherein the first gas includes C 3 H 8 , and the first gas is in a state of being thermally decomposed at a temperature of 1200 ° C to 1600 ° C. A method for manufacturing a silicon epitaxial substrate.
  6. 　前記第１ガスはＨ２で希釈されたＣ３Ｈ８を含む、請求項５に記載の炭化珪素エピタキシャル基板の製造方法。 The method for manufacturing a silicon carbide epitaxial substrate according to claim 5, wherein the first gas includes C 3 H 8 diluted with H 2 .
  7. 　前記第２ガスはＳｉＨ４を含み、前記第２ガスは４００℃以上８００℃以下の温度で加熱分解された状態である、請求項２に記載の炭化珪素エピタキシャル基板の製造方法。 3. The method for manufacturing a silicon carbide epitaxial substrate according to claim 2, wherein the second gas contains SiH 4 , and the second gas is thermally decomposed at a temperature of 400 ° C. or higher and 800 ° C. or lower.
  8. 　前記第３ガスはＮ２およびＮＨ３の少なくともいずれかを含み、前記第３ガスは６００℃以上１０００℃以下の温度で加熱分解された状態である、請求項３に記載の炭化珪素エピタキシャル基板の製造方法。 4. The silicon carbide epitaxial substrate according to claim 3, wherein the third gas includes at least one of N 2 and NH 3 , and the third gas is thermally decomposed at a temperature of 600 ° C. or higher and 1000 ° C. or lower. Production method.
  9. 　前記第３ガスはＮ２およびＮＨ３の少なくともいずれかを含み、前記第３ガスは６００℃以上１０００℃以下の温度で加熱分解された状態である、請求項４に記載の炭化珪素エピタキシャル基板の製造方法。 The third gas may comprise at least one of N 2 and NH 3, wherein the third gas is a state of being thermally decomposed at a temperature of 600 ° C. or higher 1000 ° C. or less, the silicon carbide epitaxial substrate according to claim 4 Production method.
  10. 　請求項１～請求項９のいずれか１項に記載の方法で製造された炭化珪素エピタキシャル基板を準備する工程と、
    　前記炭化珪素エピタキシャル基板を加工する工程とを備える、炭化珪素半導体装置の製造方法。     Preparing a silicon carbide epitaxial substrate manufactured by the method according to any one of claims 1 to 9,
    A process for processing the silicon carbide epitaxial substrate.
  11. 　炭化珪素単結晶基板を加熱可能に構成された反応室と、
    　炭素を含む第１ガスを供給可能に構成された第１ガス供給部と、
    　珪素を含む第２ガスを供給可能に構成された第２ガス供給部と、
    　窒素を含む第３ガスを供給可能に構成された第３ガス供給部と、
    　第１温度で、前記第１ガスを加熱可能に構成された第１加熱分解部と、
    　前記第１ガスと、前記第２ガスと、前記第３ガスとを混合可能に構成された混合部とを備え、
    　前記第１ガス供給部と、前記第２ガス供給部と、前記第３ガス供給部とは、前記混合部に繋がれており、
    　前記第１加熱分解部は、前記第１ガス供給部と前記混合部との間にある、炭化珪素エピタキシャル基板の製造装置。     A reaction chamber configured to heat the silicon carbide single crystal substrate;
    A first gas supply unit configured to be able to supply a first gas containing carbon;
    A second gas supply unit configured to be able to supply a second gas containing silicon;
    A third gas supply unit configured to be able to supply a third gas containing nitrogen;
    A first thermal decomposition unit configured to be capable of heating the first gas at a first temperature;
    A mixing unit configured to be able to mix the first gas, the second gas, and the third gas;
    The first gas supply unit, the second gas supply unit, and the third gas supply unit are connected to the mixing unit,
    The apparatus for manufacturing a silicon carbide epitaxial substrate, wherein the first thermal decomposition unit is between the first gas supply unit and the mixing unit.
  12. 　第２温度で、前記第２ガスを加熱分解可能に構成された第２加熱分解部をさらに備え、
    　前記第２加熱分解部は、前記第２ガス供給部と前記混合部との間にある、請求項１１に記載の炭化珪素エピタキシャル基板の製造装置。     A second thermal decomposition unit configured to thermally decompose the second gas at a second temperature;
    The said 2nd thermal decomposition part is a manufacturing apparatus of the silicon carbide epitaxial substrate of Claim 11 which exists between the said 2nd gas supply part and the said mixing part.
  13. 　前記第２温度は、前記第１温度より低い、請求項１２に記載の炭化珪素エピタキシャル基板の製造装置。 The silicon carbide epitaxial substrate manufacturing apparatus according to claim 12, wherein the second temperature is lower than the first temperature.
  14. 　前記第２ガスは、ＳｉＨ４を含み、
    　前記第２温度は、４００℃以上８００℃以下である、請求項１２または請求項１３に記載の炭化珪素エピタキシャル基板の製造装置。     The second gas includes SiH 4 ;
    The said 2nd temperature is a manufacturing apparatus of the silicon carbide epitaxial substrate of Claim 12 or Claim 13 which are 400 degreeC or more and 800 degrees C or less.
  15. 　第３温度で、前記第３ガスを加熱分解可能に構成された第３加熱分解部をさらに備え、
    　前記第３加熱分解部は、前記第３ガス供給部と前記混合部との間にある、請求項１１～請求項１４のいずれか１項に記載の炭化珪素エピタキシャル基板の製造装置。     A third thermal decomposition unit configured to be capable of thermally decomposing the third gas at a third temperature;
    The silicon carbide epitaxial substrate manufacturing apparatus according to any one of claims 11 to 14, wherein the third thermal decomposition section is located between the third gas supply section and the mixing section.
  16. 　前記第３温度は、６００℃以上１０００℃以下である、請求項１５に記載の炭化珪素エピタキシャル基板の製造装置。 The silicon carbide epitaxial substrate manufacturing apparatus according to claim 15, wherein the third temperature is not lower than 600 ° C and not higher than 1000 ° C.
  17. 　前記第１ガスは、Ｃ３Ｈ８を含み、
    　前記第１温度は、１２００℃以上１６００℃以下である、請求項１１～請求項１６のいずれか１項に記載の炭化珪素エピタキシャル基板の製造装置。     The first gas includes C 3 H 8 ;
    The silicon carbide epitaxial substrate manufacturing apparatus according to any one of claims 11 to 16, wherein the first temperature is not less than 1200 ° C and not more than 1600 ° C.
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