# US 11,114,295 B2 · Epitaxial silicon carbide single crystal wafer and process for producing the same

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,114,295 B2
- Document ID: US11114295B2
- Status: Granted
- Kind: B2
- Application number: 16/901,435
- Filed: 2020-06-15
- Published: 2020-10-01
- Granted: 2021-09-07
- Earliest claimed: 2015-02-18
- Assignees: Showa Denko K.K.
- Applicants: Showa Denko K.K.
- Inventors: Takashi Aigo; Wataru Ito; Tatsuo Fujimoto
- Web page: https://patentgrep.com/patent/US11114295B2

## CPC

- H10P 14/2904: {Silicon carbide}
- C23C 16/029: {Graded interfaces}
- C23C 16/325: {Silicon carbide}
- C23C 16/45523: {Pulsed gas flow or change of composition over time}
- C30B 25/16: Controlling or regulating (controlling or regulating in general G05)
- C30B 25/183: {being provided with a buffer layer, e.g. a lattice matching layer}
- C30B 25/186: {being specially pre-treated by, e.g. chemical or physical means}
- C30B 25/20: the substrate being of the same materials as the epitaxial layer
- C30B 29/06: Silicon
- C30B 29/36: Carbides
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2926: {Crystal orientations}
- H10P 14/3208: {Silicon carbide}
- H10P 14/3408: {Silicon carbide}
- H10P 14/3442: {N-type}
- H10P 14/36: {characterised by treatments done before the formation of the materials}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- 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)
- 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

## Abstract

An epitaxial silicon carbide single crystal wafer having a small depth of shallow pits and having a high quality silicon carbide single crystal thin film and a method for producing the same are provided. The epitaxial silicon carbide single crystal wafer according to the present invention is produced by forming a buffer layer made of a silicon carbide epitaxial film having a thickness of 1 μm or more and 10 μm or less by adjusting the ratio of the number of carbon to that of silicon (C/Si ratio) contained in a silicon-based and carbon-based material gas to 0.5 or more and 1.0 or less, and then by forming a drift layer made of a silicon carbide epitaxial film at a growth rate of 15 μm or more and 100 μm or less per hour. According to the present invention, the depth of the shallow pits observed on the surface of the drift layer can be set at 30 nm or less.

## Claims

### Claim 1

An epitaxial silicon carbide single crystal wafer comprising:
a silicon carbide single crystal substrate having an off angle of 4° or less, which is an angle tilted in the <11-20> direction with respect to a (0001) plane;
a buffer layer, formed on the silicon carbide single crystal substrate, having a doping density of 1×1018 atms/cm3 or more and 1×1019 atms/cm3 or less and consisting of a silicon carbide epitaxial film having a thickness of 5 μm or more and 10 μm or less; and
a drift layer, formed on the buffer layer, having a doping density of 1×1015 atms/cm3 or more and 1×1017 atms/cm3 or less and consisting of a silicon carbide epitaxial film having a thickness of 10 μm or more and 30 μm or less,
wherein a depth of shallow pits on the surface of the drift layer is 19 nm or less, and
wherein the shallow pits are formed by a screw dislocation of the silicon carbide single crystal wafer.

### Claim 2 (depends on 1)

The epitaxial silicon carbide single crystal wafer according to claim 1,
wherein when a Schottky barrier diode is formed by providing a Ni-based ohmic electrode on a side of the silicon carbide single crystal substrate and a Ni-based Schottky electrode on a side of the drift layer, a leakage current at a reverse applied voltage of 400 V becomes 1×10−11 A/cm2 or more and 1×10−8 A/cm2 or less.