# US 10,770,550 B2 · Silicon carbide epitaxial substrate having grooves extending along main surface and method of manufacturing silicon carbide semiconductor device

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- Number: US 10,770,550 B2
- Document ID: US10770550B2
- Status: Granted
- Kind: B2
- Application number: 16/660,878
- Filed: 2019-10-23
- Published: 2020-02-13
- Granted: 2020-09-08
- Earliest claimed: 2015-11-24
- Assignees: Sumitomo Electric Industries, Ltd.
- Applicants: Sumitomo Electric Industries, Ltd.
- Inventors: Keiji Wada; Hironori Itoh; Taro Nishiguchi
- Web page: https://patentgrep.com/patent/US10770550B2

## CPC

- C30B 25/20: the substrate being of the same materials as the epitaxial layer
- C30B 29/36: Carbides
- H10D 12/031: {of IGBTs}
- H10D 30/0291: {of vertical DMOS [VDMOS] FETs}
- H10D 30/60: Insulated-gate field-effect transistors [IGFET] (H10D30/40 takes precedence)
- H10D 62/57: the imperfections being on the surface of the semiconductor body, e.g. the body having a roughened surface
- H10D 62/81: of structures exhibiting quantum-confinement effects, e.g. single quantum wells; of structures having periodic or quasi-periodic potential variation
- H10D 62/832: being Group IV materials comprising two or more elements, e.g. SiGe
- H10D 62/8325: {Silicon carbide}
- H10P 14/20: of semiconductor materials
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2904: {Silicon carbide}
- H10P 14/2926: {Crystal orientations}
- H10P 14/3408: {Silicon carbide}
- H10P 14/3442: {N-type}
- 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. An average value of carrier concentration in the silicon carbide layer is not less than 1×1015 cm−3 and not more than 5×1016 cm−3. In-plane uniformity of the carrier concentration is not more than 2%. The second main surface has: a groove 80 extending in one direction along the second main surface, a width of the groove in the one direction being twice or more as large as a width thereof in a direction perpendicular to the one direction, and a maximum depth of the groove from the second main surface being not more than 10 nm; and a carrot defect. A value obtained by dividing a number of the carrot defects by a number of the grooves is not more than 1/500.

## 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 opposite to a surface thereof in contact with the silicon carbide single-crystal substrate,
an average value of carrier concentration in the silicon carbide layer being not less than 1×1015 cm−3 and not more than 5×1016 cm−3,
in-plane uniformity of the carrier concentration being not more than 2%,
the second main surface having
grooves extending in one direction along the second main surface, a width of each of the grooves in the one direction being twice or more as large as a width thereof in a direction perpendicular to the one direction, and a maximum depth of each of the grooves from the second main surface being not more than 10 nm, and
one or more carrot defects,
a value obtained by dividing a number of the one or more carrot defects by a number of the grooves being not more than 1/500,
the silicon carbide single-crystal substrate having a diameter of not less than 150 mm.

### Claim 2 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein
each of the grooves includes a first groove portion and a second groove portion provided continuously with the first groove portion,
the first groove portion is at one end portion of each of the grooves in the one direction, and
the second groove portion extends from the first groove portion along the one direction to the other end portion opposite to the one end portion, and has a depth from the second main surface which is smaller than a maximum depth of the first groove portion.

### Claim 3 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein
the value is not more than 1/1000.

### Claim 4 (depends on 3)

The silicon carbide epitaxial substrate according to claim 3, wherein
the value is not more than 1/5000.

### Claim 5 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein
a density of the carrot defects in the second main surface is not more than 1 cm−2.

### Claim 6 (depends on 5)

The silicon carbide epitaxial substrate according to claim 5, wherein
the density is not more than 0.5 cm−2.

### Claim 7 (depends on 6)

The silicon carbide epitaxial substrate according to claim 6, wherein
the density is not more than 0.1 cm−2.

### Claim 8 (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.

### Claim 9 (depends on 1)

The silicon carbide epitaxial substrate according to claim 1, wherein the first main surface is a plane tilted in a <11-20> direction at an angle of not more than 4° from a {0001} plane.