# US 9,752,254 B2 · Method for manufacturing a single-crystal 4H—SiC substrate

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- Number: US 9,752,254 B2
- Document ID: US9752254B2
- Status: Granted
- Kind: B2
- Application number: 15/182,661
- Filed: 2016-06-15
- Published: 2016-10-13
- Granted: 2017-09-05
- Earliest claimed: 2013-03-26
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Akihito Ohno; Zempei Kawazu; Nobuyuki Tomita; Takanori Tanaka; Yoichiro Mitani; Kenichi Hamano
- Web page: https://patentgrep.com/patent/US9752254B2

## CPC

- C30B 25/20: the substrate being of the same materials as the epitaxial layer
- C30B 29/36: Carbides
- C30B 29/68: Crystals with laminate structure, e.g. "superlattices"
- Y10T 428/24331: including nonapertured component
- Y10T 428/24612: Composite web or sheet
- 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
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method for manufacturing a single-crystal 4H—SiC substrate includes preparing a 4H—SiC bulk single-crystal substrate having a flat surface, and growing an epitaxial first single-crystal 4H—SiC layer having recesses on the 4H—SiC bulk single-crystal substrate to a thickness X, measured in micrometers (μm). The recesses have a diameter Y, measured in micrometers, no smaller than 0.2*X and no larger than 2*X. In addition, the recesses have a depth Z, when measured in micrometers, no smaller than (0.95*X+0.5*10−3), and no larger than 10*X*10−3.

## Claims

### Claim 1

A method for manufacturing a single-crystal 4H—SiC substrate comprising:
preparing a 4H—SiC bulk single-crystal substrate having a flat surface; and
growing an epitaxial first single-crystal 4H—SiC layer having recesses on the 4H—SiC bulk single-crystal substrate, wherein
the epitaxial first single-crystal 4H—SiC layer has a thickness X (μm),
the recesses have a diameter Y (μm) no smaller than 0.2*X (μm) and no larger than 2*X (μm), and
the recesses have a depth Z (nm) no smaller than (0.95*X+0.5) and no larger than 10*X.

### Claim 2 (depends on 1)

The method for manufacturing a single-crystal 4H—SiC substrate according to claim 1, including growing the epitaxial first single crystal 4H—SiC layer at a temperature and pressure so that the recesses are formed in a growth surface of the epitaxial first single-crystal 4H—SiC layer.

### Claim 3 (depends on 1)

The method for manufacturing a single-crystal 4H—SiC substrate according to claim 1, wherein the recesses formed in a surface of the epitaxial first single-crystal 4H—SiC layer have a density of at least 10/cm2.

### Claim 4 (depends on 1)

The method for manufacturing a single-crystal 4H—SiC substrate according to claim 1, further comprising growing an epitaxial second single-crystal 4H—SiC layer on the epitaxial first single-crystal 4H—SiC layer, burying the recesses.

### Claim 5

A method for manufacturing a single-crystal 4H—SiC substrate comprising:
preparing a 4H—SiC bulk single-crystal substrate having a flat surface; and
growing an epitaxial first single-crystal 4H—SiC layer having recesses on the 4H—SiC bulk single-crystal substrate to a thickness X, measured in micrometers (μm), wherein
the recesses have a diameter Y, measured in micrometers, no smaller than 0.2*X and no larger than 2*X, and
the recesses have a depth Z, when measured in micrometers, no smaller than (0.95*X+0.5)*10−3, and no larger than 10*X*10−3.

### Claim 6 (depends on 5)

The method for manufacturing a single-crystal 4H—SiC substrate according to claim 5, including growing the epitaxial first single crystal 4H—SiC layer at a temperature and pressure so that the recesses are formed in a growth surface of the epitaxial first single-crystal 4H—SiC layer.

### Claim 7 (depends on 5)

The method for manufacturing a single-crystal 4H—SiC substrate according to claim 5, including forming the recesses in a growth surface of the epitaxial first single-crystal 4H—SiC layer in a density of at least 10/cm2.

### Claim 8 (depends on 5)

The method for manufacturing a single-crystal 4H—SiC substrate according to claim 5, further comprising growing an epitaxial second single-crystal 4H—SiC layer on the epitaxial first single-crystal 4H—SiC layer, burying the recesses.

### Claim 9 (depends on 5)

The method for manufacturing a single-crystal 4H—SiC substrate according to claim 5, including growing the epitaxial first single-crystal 4H—SiC layer to the thickness X no smaller than 0.3 μm and no larger than 10 μm.