# US 9,437,690 B2 · Silicon carbide substrate, semiconductor device, and methods for manufacturing them

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- Number: US 9,437,690 B2
- Document ID: US9437690B2
- Status: Granted
- Kind: B2
- Application number: 14/870,777
- Filed: 2015-09-30
- Published: 2016-01-21
- Granted: 2016-09-06
- Earliest claimed: 2012-04-02
- Assignees: Sumitomo Electric Industries, Ltd.
- Applicants: Sumitomo Electric Industries, Ltd.
- Inventors: Keiji Ishibashi
- Web page: https://patentgrep.com/patent/US9437690B2

## CPC

- H10D 62/8325: {Silicon carbide}
- C30B 23/025: {characterised by the substrate}
- C30B 29/36: Carbides
- C30B 31/04: by contacting with diffusion materials in the liquid state
- H10D 12/031: {of IGBTs}
- H10D 30/87: FETs having Schottky gate electrodes, e.g. metal-semiconductor FETs [MESFET] {(FETs having Schottky contact on top of heterojunction gate H10D30/801)}
- H10D 62/40: Crystalline structures
- H10D 62/405: {Orientations of crystalline planes}
- H10D 62/53: the imperfections being within the semiconductor body
- H10D 62/60: Impurity distributions or concentrations
- H10P 14/2904: {Silicon carbide}
- H10P 50/00: Etching of wafers, substrates or parts of devices
- H10P 90/00: Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement
- H10P 90/12: {Preparing bulk and homogeneous wafers}
- H10P 90/126: {by chemical etching}
- H10P 90/129: {by polishing}
- H10P 90/1902: {Preparing horizontally inhomogeneous wafers}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- 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
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A silicon carbide substrate has a first main surface, and a second main surface opposite to the first main surface. A region including at least one main surface of the first and second main surfaces is made of single-crystal silicon carbide. In the one main surface, sulfur atoms are present at not less than 60×1010 atoms/cm2 and not more than 2000×1010 atoms/cm2, and carbon atoms as an impurity are present at not less than 3 at % and not more than 25 at %. Thereby, a silicon carbide substrate having a stable surface, a semiconductor device using the substrate, and methods for manufacturing them can be provided.

## Claims

### Claim 1

A silicon carbide substrate, comprising:
a first main surface; and
a second main surface opposite to said first main surface,
a region including at least one main surface of said first and second main surfaces consisting essentially of single-crystal silicon carbide,
sulfur atoms being present in said one main surface at not less than 80×1010 atoms/cm2 and not more than 800×1010 atoms/cm2, and carbon atoms as an impurity being present in said one main surface at not less than 3 atomic percent (at %) and not more than 25 atomic percent (at %).

### Claim 2 (depends on 1)

The silicon carbide substrate according to claim 1, wherein chlorine atoms are present in said one main surface at not more than 3000×1010 atoms/cm2.

### Claim 3 (depends on 1)

The silicon carbide substrate according to claim 1, wherein oxygen atoms are present in said one main surface at not less than 3 atomic percent (at %) and not more than 30 atomic percent (at %).

### Claim 4 (depends on 1)

The silicon carbide substrate according to claim 1, wherein a metal impurity is present in said one main surface at not more than 4000×1010 atoms/cm2.

### Claim 5 (depends on 1)

The silicon carbide substrate according to claim 1, wherein said one main surface has a surface roughness of not more than 0.5 nm when evaluated in Rq.

### Claim 6 (depends on 1)

The silicon carbide substrate according to claim 1, having a diameter of not less than 110 mm.

### Claim 7 (depends on 1)

The silicon carbide substrate according to claim 1, having a diameter of not less than 125 mm and not more than 300 mm.

### Claim 8 (depends on 1)

The silicon carbide substrate according to claim 1, wherein
said single-crystal silicon carbide has a 4H structure, and
said one main surface has an off angle of not less than 0.1° and not more than 10° relative to a {0001} plane of said single-crystal silicon carbide.

### Claim 9 (depends on 1)

The silicon carbide substrate according to claim 1, wherein
said single-crystal silicon carbide has a 4H structure, and
said one main surface has an off angle of not more than 4° relative to a {03-38} plane of said single-crystal silicon carbide.

### Claim 10 (depends on 1)

The silicon carbide substrate according to claim 1, comprising:
a base layer; and
a single-crystal silicon carbide layer formed on said base layer,
wherein said one main surface is a surface of said single-crystal silicon carbide layer on a side opposite to a side facing said base layer.

### Claim 11 (depends on 1)

The silicon carbide substrate according to claim 1, wherein each concentration of sulfur atoms and carbon atoms is adjusted so that the silicon is suppressed from adhering to said one main surface.