# US 9,040,402 B2 · Fabrication method of silicon carbide semiconductor device

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- Number: US 9,040,402 B2
- Document ID: US9040402B2
- Status: Granted
- Kind: B2
- Application number: 14/388,749
- Filed: 2013-03-14
- Published: 2015-03-05
- Granted: 2015-05-26
- Earliest claimed: 2012-03-28
- Assignees: Fuji Electric Co., Ltd.; National Institute of Advanced Industrial Science and Technology
- Applicants: Fuji Electric Co., Ltd.; National Institute of Advanced Industrial Science and Technology
- Inventors: Masahide Goto; Kenji Fukuda; Noriyuki Iwamuro
- Web page: https://patentgrep.com/patent/US9040402B2

## CPC

- H10D 12/031: {of IGBTs}
- H10D 48/01: Manufacture or treatment
- H10D 62/8325: {Silicon carbide}
- H10D 62/882: {Graphene}
- H10D 64/0115: {to silicon carbide}
- H10D 64/60: Electrodes characterised by their materials
- H10D 64/62: Electrodes ohmically coupled to a semiconductor
- H10P 50/00: Etching of wafers, substrates or parts of devices
- H10P 50/242: {of Group IV materials}
- H10P 50/692: {characterised by their composition, e.g. multilayer masks or materials}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A first metal layer (3) is formed on a back face of a silicon carbide substrate (1) to a degree such that the first metal layer (3) does not fully cover the back face of the silicon carbide substrate. Many holes (4) are formed on the back face of the silicon carbide substrate (1) by dry-etching the back face of the silicon carbide substrate (1) using the first metal layer (3) as a mask therefor. A second metal layer constituting an ohmic contact is formed on the first metal layer (3) and the back face of the silicon carbide substrate (1) including inner surfaces of the many holes (4).

## Claims

### Claim 1

A silicon carbide semiconductor device fabrication method comprising:
forming a first metal layer on a back face of a silicon carbide substrate to a degree such that the first metal layer does not fully cover the back face of the silicon carbide substrate;
forming many holes on the back face of the silicon carbide substrate by dry-etching the back face of the silicon carbide substrate using the first metal layer as a mask therefor; and
forming a second metal layer constituting an ohmic contact, on the first metal layer and the back face of the silicon carbide substrate including inner surfaces of the many holes.

### Claim 2 (depends on 1)

The silicon carbide semiconductor device fabrication method according to claim 1, wherein
the first metal layer is a nickel layer or an alloy layer including at least one of nickel, titanium, zirconium, and hafnium.

### Claim 3 (depends on 1)

The silicon carbide semiconductor device fabrication method according to claim 1, wherein
the dry-etching for the back face of the silicon carbide substrate is executed using halogen-based plasma.

### Claim 4 (depends on 1)

The silicon carbide semiconductor device fabrication method according to claim 1, wherein
the first metal layer and the second metal layer are formed by the same metal.

### Claim 5 (depends on 1)

The silicon carbide semiconductor device fabrication method according to claim 1, wherein
the forming of the first metal layer, the forming of the many holes, and the forming of the second metal layer are executed after forming a front face structure on a front face of the silicon carbide substrate.

### Claim 6 (depends on 1)

The silicon carbide semiconductor device fabrication method according to claim 1, wherein
a thickness of the first metal layer is 1 nm to 50 nm.

### Claim 7 (depends on 1)

The silicon carbide semiconductor device fabrication method according to claim 1, wherein
a vertical semiconductor device is fabricated.

### Claim 8

A silicon carbide semiconductor device fabrication method comprising:
forming a first metal layer on a back face of a silicon carbide substrate such that the first metal layer fully covers the back face of the silicon carbide substrate and thereafter, selectively removing the first metal layer causing a thickness of the first metal layer to be a thickness with which the first metal layer does not fully cover the back face of the silicon carbide substrate;
forming many holes on the back face of the silicon carbide substrate by dry-etching the back face of the silicon carbide substrate using the first metal layer as a mask therefor; and
forming a second metal layer constituting an ohmic contact, on the first metal layer and the back face of the silicon carbide substrate including inner surfaces of the many holes.

### Claim 9 (depends on 8)

The silicon carbide semiconductor device fabrication method according to claim 8, wherein
the first metal layer is a nickel layer or an alloy layer including at least one of nickel, titanium, zirconium, and hafnium.

### Claim 10 (depends on 8)

The silicon carbide semiconductor device fabrication method according to claim 8, wherein
a vertical semiconductor device is fabricated.