# US 12,765,021 B2 · Silicon carbide epitaxial substrate and method of manufacturing silicon carbide semiconductor device

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- Number: US 12,765,021 B2
- Document ID: US12765021B2
- Status: Granted
- Kind: B2
- Application number: 18/563,422
- Filed: 2022-05-16
- Published: 2024-10-31
- Granted: 2026-10-13
- Earliest claimed: 2021-05-25
- Assignees: Mitsumi Electric Co., Ltd.
- Applicants: Mitsumi Electric Co., Ltd.
- Inventors: Hiroki Nishihara; Tsubasa Honke; Takaya Miyase; Taro Enokizono
- Web page: https://patentgrep.com/patent/US12765021B2

## CPC

- H10D 62/57: the imperfections being on the surface of the semiconductor body, e.g. the body having a roughened surface
- H10D 62/8325: {Silicon carbide}
- H10D 12/481: {having gate structures on slanted surfaces, on vertical surfaces, or in grooves, e.g. trench gate IGBTs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A silicon carbide epitaxial substrate includes a silicon carbide substrate and a silicon carbide epitaxial layer. The silicon carbide epitaxial layer is on the silicon carbide substrate. The silicon carbide epitaxial layer has a main surface located opposite to an interface between the silicon carbide substrate and the silicon carbide epitaxial layer. An area density of a pit in the main surface is 1/cm2 or less. An area density of a bump in the main surface is less than 0.7/cm2. An area of the pit is 100 μm2 or less, and an area of the bump is 100 μm2 or less when viewed in a direction perpendicular to the main surface. A depth of the pit is 0.01 μm to 0.1 μm and a height of the bump is 0.01 μm to 0.1 μm in the direction perpendicular to the main surface.

## Claims

### Claim 1

A silicon carbide epitaxial substrate comprising:
a silicon carbide substrate; and
a silicon carbide epitaxial layer on the silicon carbide substrate,
wherein the silicon carbide epitaxial layer has a main surface located opposite to an interface between the silicon carbide substrate and the silicon carbide epitaxial layer,
an area density of a pit in the main surface is 1/cm2 or less,
an area density of a bump in the main surface is less than 0.1/cm2,
an area of the pit is 100 μm2 or less and an area of the bump is 100 μm2 or less when viewed in a direction perpendicular to the main surface, and
a depth of the pit is 0.01 μm to 0.1 μm and a height of the bump is 0.01 μm to 0.1 μm in the direction perpendicular to the main surface.

### Claim 2 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein the silicon carbide epitaxial layer has a thickness of 15 μm or more.

### Claim 3 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1,
wherein the silicon carbide epitaxial layer has a thickness of less than 15 μm, and
the area density of the pit in the main surface is 0.5/cm2 or less.

### Claim 4 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein an area density of a three-dimensional oblique defect in the main surface is 0.006/cm2 to 0.2/cm2.

### Claim 5 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1,
wherein an area density of a scratch in the main surface is 1/cm2 or less,
a width of the scratch is 10 μm or less and a length of the scratch is 150 mm or less when viewed in the direction perpendicular to the main surface, and
a depth of the scratch is 0.2 μm or more in the direction perpendicular to the main surface.

### Claim 6

A silicon carbide epitaxial substrate comprising:
a silicon carbide substrate; and
a silicon carbide epitaxial layer on the silicon carbide substrate,
wherein the silicon carbide epitaxial layer has a main surface located opposite to an interface between the silicon carbide substrate and the silicon carbide epitaxial layer,
an area density of a bump in the main surface is less than 0.1/cm2, and
an area density of a three-dimensional oblique defect in the main surface is 0.006/cm2 to 0.2/cm2.

### Claim 7 (depends on 1)

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