# US 10,770,296 B2 · Method of manufacturing semiconductor device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,770,296 B2
- Document ID: US10770296B2
- Status: Granted
- Kind: B2
- Application number: 16/472,142
- Filed: 2017-01-26
- Published: 2020-03-26
- Granted: 2020-09-08
- Earliest claimed: 2017-01-26
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Takeshi Murakami
- Web page: https://patentgrep.com/patent/US10770296B2

## CPC

- H10D 64/01366: {the semiconductor being silicon carbide}
- H10D 12/031: {of IGBTs}
- H10D 12/032: {of vertical IGBTs}
- H10D 30/0291: {of vertical DMOS [VDMOS] FETs}
- H10D 30/665: {having edge termination structures}
- H10D 62/8325: {Silicon carbide}
- H10D 64/0115: {to silicon carbide}
- H10D 64/62: Electrodes ohmically coupled to a semiconductor
- H10P 14/6314: {of a metallic layer}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Exposure of a gate conductive film covered by an interlayer insulation film in a unit cell portion is reduced when a gate contact region is formed. A method of manufacturing a semiconductor device includes forming a gate conductive film to come in contact with a gate oxide film in a unit cell portion, forming a gate wire to come in contact with the gate oxide film in a termination region, forming a first insulation film on an upper surface of the gate wire in the termination region, subjecting an upper surface of the gate conductive film in the unit cell portion to thermal oxidation with use of the first insulation film as a mask to form a thermal oxide film on the upper surface of the gate conductive film, and forming a second insulation film covering the first insulation film and the thermal oxide film.

## Claims

### Claim 1

A method of manufacturing a semiconductor device, the method comprising:
forming a gate oxide film on an upper surface of a semiconductor layer;
forming a gate conductive film to come in contact with the gate oxide film in a unit cell portion;
forming a gate wire to come in contact with the gate oxide film in a termination region provided to surround the unit cell portion in plan view;
forming a first insulation film on an upper surface of the gate wire in the termination region;
subjecting an upper surface of the gate conductive film in the unit cell portion to thermal oxidation with use of the first insulation film as a mask to form a thermal oxide film on the upper surface of the gate conductive film; and
forming a second insulation film covering the first insulation film and the thermal oxide film.

### Claim 2 (depends on 1)

The method of manufacturing a semiconductor device according to claim 1, wherein
the second insulation film is an oxide film.

### Claim 3 (depends on 1)

The method of manufacturing a semiconductor device according to claim 1, wherein
a film thickness of the thermal oxide film is 0.5 times or more as large as a film thickness of the second insulation film.

### Claim 4 (depends on 1)

The method of manufacturing a semiconductor device according to claim 1, wherein
a source contact region is formed in the unit cell portion, and
a silicide is formed in the source contact region.

### Claim 5 (depends on 4)

The method of manufacturing a semiconductor device according to claim 4, wherein
after the silicide is formed in the unit cell portion, a gate contact region is formed in the termination region.

### Claim 6 (depends on 1)

The method of manufacturing a semiconductor device according to claim 1, wherein
the semiconductor layer is made of SiC.

### Claim 7 (depends on 1)

The method of manufacturing a semiconductor device according to claim 1, wherein
the second insulation film covering an upper surface of the first insulation film and a side surface of the gate wire, and an upper surface of the thermal oxide film and a side surface of the gate conductive film is formed.

### Claim 8 (depends on 1)

The method of manufacturing a semiconductor device according to claim 1, wherein
a field oxide film is formed on the upper surface of the semiconductor layer in the termination region, and
the gate oxide film is formed on an upper surface of the field oxide film in the termination region.

### Claim 9 (depends on 1)

The method of manufacturing a semiconductor device according to claim 1, wherein
the thermal oxide film is formed also on a side surface of the gate conductive film, in addition to the upper surface of the gate conductive film.