# US 11,346,018 B2 · Silicon carbide substrate production method and silicon carbide substrate

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- Number: US 11,346,018 B2
- Document ID: US11346018B2
- Status: Granted
- Kind: B2
- Application number: 16/489,814
- Filed: 2018-03-01
- Published: 2019-12-19
- Granted: 2022-05-31
- Earliest claimed: 2017-03-02
- Assignees: Shin-Etsu Chemical Co., Ltd.; Cusic Inc.
- Applicants: Shin-Etsu Chemical Co., Ltd.; CUSIC Inc.
- Inventors: Hiroyuki Nagasawa; Yoshihiro Kubota; Shoji Akiyama
- Web page: https://patentgrep.com/patent/US11346018B2

## CPC

- C30B 33/10: in solutions or melts
- C23C 16/325: {Silicon carbide}
- C30B 25/18: characterised by the substrate
- C30B 29/36: Carbides
- H10D 62/8325: {Silicon carbide}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2904: {Silicon carbide}
- H10P 14/3238: {being insulating materials}
- H10P 14/3408: {Silicon carbide}
- H10P 72/74: {using temporarily an auxiliary support}
- H10P 90/1904: {Preparing vertically inhomogeneous wafers}
- H10P 14/3456: {Polycrystalline}
- H10P 72/7424: {used as a support during the manufacture of self-supporting substrates}
- H10P 72/744: {Details of chemical or physical process used for separating the auxiliary support from a device or a wafer}
- H10P 90/12: {Preparing bulk and homogeneous wafers}
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- 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 (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A silicon carbide substrate production method includes: the step of providing covering layers 1b, 1b, each containing silicon oxide, silicon nitride, silicon carbonitride, or silicide, respectively on both surfaces of a base material substrate 1a carbon, silicon or silicon carbide, and turning the surface of each of the covering layers 1b, 1b into a smooth surface to prepare a support substrate 1; a step of forming a polycrystalline silicon carbide film 10 on both surfaces of the support substrate 1 by a gas phase growth method or a liquid phase growth method; and a step of separating the polycrystalline silicon carbide films from the support substrate while preserving, on the surface thereof, the smoothness of the covering layer surfaces 1b, 1b by chemically removing at least the covering layers 1b, 1b, from the support substrate 1. The silicon carbide substrate has a smooth surface and reduced internal stress.

## Claims

### Claim 1

A method for producing a silicon carbide substrate, comprising steps of:
providing covering layers each containing silicon oxide, silicon nitride, silicon carbonitride or silicide on both surfaces of a base substrate made of carbon, silicon or silicon carbide to prepare a support substrate having the covering layers each with a smooth surface that has an arithmetic mean roughness Ra of 0.3 nm or less;
forming polycrystalline silicon carbide films on both surfaces, each being the smooth surface of a corresponding one of the covering layers, of the support substrate by a vapor deposition method or a liquid phase growth method; and
chemically removing at least the covering layers in the support substrate to separate the polycrystalline silicon carbide films from the support substrate such that a newly exposed, uncovered surface of each polycrystalline silicon carbide film, which has been in contact with the smooth surface of the corresponding one of the covering layers, has an arithmetic mean roughness Ra of 0.3 nm or less, and obtaining the polycrystalline silicon carbide films as silicon carbide substrates each having a crystal grain size of 10 nm or more and 10 μm or less, and an arithmetic mean roughness Ra of at least one of its main surfaces, being the newly exposed, uncovered surface, of 0.3 nm or less.

### Claim 2 (depends on 1)

The method for producing a silicon carbide substrate according to claim 1, wherein the support substrate is prepared by smoothing the both surfaces of the base substrate, and forming the covering layers made of silicon oxide, silicon nitride, silicon carbonitride or silicide on the smoothed both surfaces of the base substrate, wherein the smoothed both surfaces of the base substrate exhibit an arithmetic mean roughness Ra of 0.1 nm or less.

### Claim 3 (depends on 1)

The method for producing a silicon carbide substrate according to claim 1, wherein the support substrate is prepared by forming covering layers made of phospho silicate glass or boro-phospho silicate glass on the both surfaces of the base substrate, and reflowing the covering layers so as to form the smooth surface of each of the covering layers.

### Claim 4 (depends on 1)

The method for producing a silicon carbide substrate according to claim 1, wherein the polycrystalline silicon carbide films are formed by a thermal CVD method.