# US 12,014,924 B2 · Silicon carbide epitaxial substrate and method for manufacturing silicon carbide semiconductor device

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- Number: US 12,014,924 B2
- Document ID: US12014924B2
- Status: Granted
- Kind: B2
- Application number: 17/258,967
- Filed: 2019-06-14
- Published: 2021-10-14
- Granted: 2024-06-18
- Earliest claimed: 2018-07-20
- Assignees: Sumitomo Electric Industries, Ltd.
- Applicants: Sumitomo Electric Industries, Ltd.
- Inventors: Kenji Kanbara; Hironori Itoh; Tsutomu Hori
- Web page: https://patentgrep.com/patent/US12014924B2

## CPC

- H10P 14/3408: {Silicon carbide}
- C30B 29/36: Carbides
- H10D 12/031: {of IGBTs}
- H10D 30/0291: {of vertical DMOS [VDMOS] FETs}
- H10D 30/66: Vertical DMOS [VDMOS] FETs
- H10D 62/405: {Orientations of crystalline planes}
- 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}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2904: {Silicon carbide}
- H10P 14/2926: {Crystal orientations}
- H10P 14/36: {characterised by treatments done before the formation of the materials}
- H10P 30/2042: {into crystalline silicon carbide}
- H10P 30/21: {of electrically active species}
- H10P 30/28: characterised by an annealing step, e.g. for activation of dopants
- H10P 54/00: Cutting or separating 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
- H10D 12/032: {of vertical IGBTs}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- 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

## Abstract

When a value obtained by dividing the number of the one or more second regions by a total of the number of the one or more first regions and the number of the one or more second regions is defined as a first defect free area ratio, a value obtained by dividing the number of the one or more fourth regions by a total of the number of the one or more third regions and the number of the one or more fourth regions is defined as a second defect free area ratio, and a value obtained by dividing the number of the one or more macroscopic defects by an area of the central region is defined as X cm−2, A is smaller than B, B is less than or equal to 4, X is more than 0 and less than 4, and a Formula 1 is satisfied.

## Claims

### Claim 1

A silicon carbide epitaxial substrate comprising:
a silicon carbide substrate; and
a silicon carbide epitaxial film located on the silicon carbide substrate, wherein
a main front surface of the silicon carbide epitaxial film includes an outer edge, an outer peripheral region located within 3 mm from the outer edge, and a central region surrounded by the outer peripheral region,
a maximum diameter of the main front surface is more than or equal to 150 mm,
the central region has one or more macroscopic defects,
wherein when the central region is divided into a plurality of first square regions each having an area of A cm2, the plurality of first square regions have one or more first regions having the one or more macroscopic defects and one or more second regions not having the one or more macroscopic defects,
wherein when the central region is divided into a plurality of second square regions each having an area of B cm2, the plurality of second square regions have one or more third regions having the one or more macroscopic defects and one or more fourth regions not having the one or more macroscopic defects,
wherein when a value obtained by dividing the number of the one or more second regions by a total of the number of the one or more first regions and the number of the one or more second regions is defined as a first defect free area ratio, a value obtained by dividing the number of the one or more fourth regions by a total of the number of the one or more third regions and the number of the one or more fourth regions is defined as a second defect free area ratio, and a value obtained by dividing the number of the one or more macroscopic defects by an area of the central region is defined as X cm−2, A is smaller than B, B is less than or equal to 4, X is more than 0 and less than 4, and a Formula 1 is satisfied:
e
(
A
·
B
)
⁢
X
<
Second
⁢
Defect
⁢
Free
⁢
Area
⁢
Ratio
First
⁢
Defect
⁢
Free
⁢
Area
⁢
Ratio
<
1
,
(
Formula
⁢
1
)
wherein when Formula 1 is satisfied the macroscopic defects are more locally concentrated than when Formula 1 is not satisfied.

### Claim 2 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein B is less than or equal to 2.

### Claim 3 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein B is less than or equal to 0.5.

### Claim 4 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein B is less than or equal to 0.25.

### Claim 5 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein A is more than or equal to 0.01.

### Claim 6 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein A is more than or equal to 0.04.

### Claim 7 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein A is 0.04 and B is 0.25.

### Claim 8 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein a polytype of silicon carbide of each of the silicon carbide substrate and the silicon carbide epitaxial film is 4H.

### Claim 9 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein each of the silicon carbide substrate and the silicon carbide epitaxial film includes an n type impurity.

### Claim 10 (depends on 1)

A method for manufacturing a silicon carbide semiconductor device, the method comprising:
preparing the silicon carbide epitaxial substrate recited in claim 1; and
processing the silicon carbide epitaxial substrate.

### Claim 11

A silicon carbide epitaxial substrate comprising:
a silicon carbide substrate; and
a silicon carbide epitaxial film located on the silicon carbide substrate, wherein
a polytype of silicon carbide of each of the silicon carbide substrate and the silicon carbide epitaxial film is 4H,
each of the silicon carbide substrate and the silicon carbide epitaxial film includes an n type impurity,
a main front surface of the silicon carbide epitaxial film includes an outer edge, an outer peripheral region located within 3 mm from the outer edge, and a central region surrounded by the outer peripheral region,
a maximum diameter of the main front surface is more than or equal to 150 mm,
the central region has one or more macroscopic defects,
wherein when the central region is divided into a plurality of first square regions each having an area of A cm2, the plurality of first square regions have one or more first regions having the one or more macroscopic defects and one or more second regions not having the one or more macroscopic defects,
wherein when the central region is divided into a plurality of second square regions each having an area of B cm2, the plurality of second square regions have one or more third regions having the one or more macroscopic defects and one or more fourth regions not having the one or more macroscopic defects,
wherein when a value obtained by dividing the number of the one or more second regions by a total of the number of the one or more first regions and the number of the one or more second regions is defined as a first defect free area ratio, a value obtained by dividing the number of the one or more fourth regions by a total of the number of the one or more third regions and the number of the one or more fourth regions is defined as a second defect free area ratio, and a value obtained by dividing the number of the one or more macroscopic defects by an area of the central region is defined as X cm−2, A is 0.04, B is 0.25, X is more than 0 and less than 4, and a Formula 1 is satisfied:
e
(
A
·
B
)
⁢
X
<
Second
⁢
Defect
⁢
Free
⁢
Area
⁢
Ratio
First
⁢
Defect
⁢
Free
⁢
Area
⁢
Ratio
<
1
,
(
Formula
⁢
1
)
wherein when Formula 1 is satisfied the macroscopic defects are more locally concentrated than when Formula 1 is not satisfied.