# US 10,370,775 B2 · Silicon carbide epitaxial wafer manufacturing method, silicon carbide semiconductor device manufacturing method and silicon carbide epitaxial wafer manufacturing apparatus

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- Number: US 10,370,775 B2
- Document ID: US10370775B2
- Status: Granted
- Kind: B2
- Application number: 15/372,949
- Filed: 2016-12-08
- Published: 2017-11-02
- Granted: 2019-08-06
- Earliest claimed: 2016-04-27
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Akihito Ohno; Kenichi Hamano; Takashi Kanazawa
- Web page: https://patentgrep.com/patent/US10370775B2

## CPC

- C30B 29/36: Carbides
- C23C 16/325: {Silicon carbide}
- C30B 25/14: Feed and outlet means for the gases; Modifying the flow of the reactive gases
- C30B 25/20: the substrate being of the same materials as the epitaxial layer
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2904: {Silicon carbide}
- H10P 14/3408: {Silicon carbide}
- H10P 14/36: {characterised by treatments done before the formation of the materials}
- 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
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A silicon carbide epitaxial wafer manufacturing method includes: a stabilization step of nitriding, oxidizing or oxynitriding and stabilizing silicon carbide attached to an inner wall surface of a growth furnace; after the stabilization step, a bringing step of bringing a substrate in the growth furnace; and after the bringing step, a growth step of epitaxially growing a silicon carbide epitaxial layer on the substrate by supplying a process gas into the growth furnace to manufacture a silicon carbide epitaxial wafer.

## Claims

### Claim 1

A silicon carbide epitaxial wafer manufacturing method comprising:
a stabilization step of nitriding, oxidizing or oxynitriding and stabilizing silicon carbide attached to an inner wall surface of a growth furnace;
after the stabilization step, a bringing step of bringing a substrate into the growth furnace; and
after the bringing step, a growth step of epitaxially growing a silicon carbide epitaxial layer on the substrate by supplying a process gas into the growth furnace to manufacture a silicon carbide epitaxial wafer, such that a surface defect density of the silicon carbide epitaxial layer is decreased as compared to a process wherein the stabilization step is not performed.

### Claim 2 (depends on 1)

The silicon carbide epitaxial wafer manufacturing method according to claim 1, wherein the silicon carbide epitaxial wafer is taken out of the growth furnace, and
the stabilization step, the bringing step and the growth step are thereafter repeated to manufacture a plurality of silicon carbide epitaxial wafers.

### Claim 3 (depends on 1)

The silicon carbide epitaxial wafer manufacturing method according to claim 1, wherein the growth step is performed by placing the growth furnace into a first manufacturing apparatus, and the stabilization step is performed by placing the growth furnace into a second manufacturing apparatus different from the first manufacturing apparatus.

### Claim 4

A silicon carbide epitaxial wafer manufacturing method comprising:
a bringing step of bringing a substrate into a growth furnace;
after the bringing step, a growth step of epitaxially growing a silicon carbide epitaxial layer on the substrate by heating the substrate and supplying a process gas into the growth furnace to manufacture a silicon carbide epitaxial wafer; and
a stabilization step of nitriding, oxidizing or oxynitriding and stabilizing silicon carbide attached to an inner wall surface of the growth furnace by supplying at least one of an oxygen containing gas and a nitrogen containing gas into the growth furnace during lowering of temperature after the growth step, such that a surface defect density of a subsequently processed silicon carbide epitaxial layer is decreased as compared to a process wherein the stabilization step is not performed.

### Claim 5 (depends on 4)

The silicon carbide epitaxial wafer manufacturing method according to claim 4, wherein the growth step is performed by placing the growth furnace into a first manufacturing apparatus, and the stabilization step is performed by placing the growth furnace into a second manufacturing apparatus different from the first manufacturing apparatus.

### Claim 6 (depends on 1)

A silicon carbide semiconductor device manufacturing method wherein a silicon carbide semiconductor device is manufactured by using the silicon carbide epitaxial wafer according to claim 1.

### Claim 7 (depends on 4)

A silicon carbide semiconductor device manufacturing method wherein a silicon carbide semiconductor device is manufactured by using the silicon carbide epitaxial wafer according to claim 4.

### Claim 8 (depends on 1)

The silicon carbide epitaxial wafer manufacturing method according to claim 1, wherein the silicon carbide attached to an inner wall surface of the growth furnace is in dendritic form.

### Claim 9 (depends on 4)

The silicon carbide epitaxial wafer manufacturing method according to claim 4, wherein the silicon carbide attached to an inner wall surface of the growth furnace is in dendritic form.

### Claim 10 (depends on 1)

The silicon carbide epitaxial wafer manufacturing method according to claim 1, wherein the silicon carbide attached to an inner wall surface of the growth furnace is introduced in an epitaxial growth process.

### Claim 11 (depends on 4)

The silicon carbide epitaxial wafer manufacturing method according to claim 4, wherein the silicon carbide attached to an inner wall surface of the growth furnace is introduced in the growth step.