# US 10,865,501 B2 · Silicon carbide epitaxial substrate and method of manufacturing silicon carbide semiconductor device

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- Number: US 10,865,501 B2
- Document ID: US10865501B2
- Status: Granted
- Kind: B2
- Application number: 15/754,097
- Filed: 2016-07-04
- Published: 2018-08-30
- Granted: 2020-12-15
- Earliest claimed: 2015-09-11
- Assignees: Sumitomo Electric Industries, Ltd.
- Applicants: Sumitomo Electric Industries, Ltd.
- Inventors: Tsutomu Hori; Hironori Itoh
- Web page: https://patentgrep.com/patent/US10865501B2

## CPC

- C30B 29/36: Carbides
- C30B 25/183: {being provided with a buffer layer, e.g. a lattice matching layer}
- C30B 25/20: the substrate being of the same materials as the epitaxial layer
- H10D 12/031: {of IGBTs}
- H10D 30/0291: {of vertical DMOS [VDMOS] FETs}
- H10D 30/66: Vertical DMOS [VDMOS] FETs
- H10D 62/8325: {Silicon carbide}
- H10D 64/0115: {to silicon carbide}
- H10D 64/01366: {the semiconductor being silicon carbide}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2904: {Silicon carbide}
- H10P 14/2926: {Crystal orientations}
- H10P 14/3208: {Silicon carbide}
- H10P 14/3408: {Silicon carbide}
- H10P 14/3442: {N-type}
- H10P 14/3466: {Crystal orientation}
- H10P 14/6308: {of Group IV semiconductors}
- H10P 30/2042: {into crystalline silicon carbide}
- H10P 30/21: {of electrically active species}
- H10P 54/00: Cutting or separating of wafers, substrates or parts of devices
- H10D 12/032: {of vertical IGBTs}
- H10D 12/441: {Vertical IGBTs}
- H10D 18/655: {produced by insulated gate structures}
- H10D 62/157: {Impurity concentrations or distributions}
- H10P 14/20: of semiconductor materials
- 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
- 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 epitaxial substrate has a silicon carbide single-crystal substrate and a silicon carbide layer. A first ratio of an absolute value of a difference between a dopant density in a first end region and a dopant density in a central region to an average value of the dopant density in the first end region and the dopant density in the central region is not more than 40%. A second ratio of an absolute value of a difference between a dopant density in a second end region and the dopant density in the central region to an average value of the dopant density in the second end region and the dopant density in the central region is not more than 40%.

## Claims

### Claim 1

A silicon carbide epitaxial substrate comprising:
a silicon carbide single-crystal substrate including a first main surface; and
a silicon carbide layer on the first main surface,
the silicon carbide layer including a second main surface and a fourth main surface, the second main surface being opposite to the fourth main surface in direct contact with the silicon carbide single-crystal substrate,
the second main surface having a maximum diameter of not less than 100 mm and not more than 300 mm,
the silicon carbide single-crystal substrate and the silicon carbide layer being provided with a linear orientation flat,
the silicon carbide layer having a central region, a first end region and a second end region,
the central region being located 2 μm away from a center of the second main surface toward the first main surface in a direction perpendicular to the second main surface,
the first end region being located 2 μm away from the second main surface toward the first main surface in a direction perpendicular to the second main surface, and being located 1 mm away from the orientation flat toward the central region,
the second end region being located 2 μm away from the second main surface toward the first main surface in a direction perpendicular to the second main surface and in a direction circumferentially rotated 90° counterclockwise from the first end region when viewed from above the second main surface so that the silicon carbide layer is on other side of the second main surface, and being located 1 mm away from an outer edge of the silicon carbide layer toward the central region,
the silicon carbide layer having a thickness of not less than 5 μm and not more than 15 μm,
a first ratio of an absolute value of a difference between a dopant density in the first end region and a dopant density in the central region to an average value of the dopant density in the first end region and the dopant density in the central region being more than 20% and not more than 40%,
a second ratio of an absolute value of a difference between a dopant density in the second end region and the dopant density in the central region to an average value of the dopant density in the second end region and the dopant density in the central region being more than 20% and not more than 40%.

### Claim 2 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein
the first ratio is not more than 30%.

### Claim 3 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein
the second ratio is not more than 30%.

### Claim 4 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein
the maximum diameter is not less than 150 mm.

### Claim 5 (depends on 1)

A method of manufacturing a silicon carbide semiconductor device, comprising:
preparing the silicon carbide epitaxial substrate according to claim 1; and
processing the silicon carbide epitaxial substrate.