# US 7,071,076 B2 · Method of manufacturing semiconductor device

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- Number: US 7,071,076 B2
- Document ID: US7071076B2
- Status: Granted
- Kind: B2
- Application number: 10/875,212
- Filed: 2004-06-25
- Published: 2004-12-30
- Granted: 2006-07-04
- Earliest claimed: 2003-06-26
- Assignees: Oki Electric Industry Co., Ltd.
- Inventors: Guo Lin Liu
- Web page: https://patentgrep.com/patent/US7071076B2

## CPC

- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D 84/0151: {Manufacturing their isolation regions}
- H10W 10/014: {using trench refilling with dielectric materials, e.g. shallow trench isolations}
- H10W 10/17: formed using trench refilling with dielectric materials, e.g. shallow trench isolations
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A semiconductor device has an STI oxide film (106), of which surface is positioned higher than the surface of the silicon substrate (100) to prevent a pointed portion and a thin film thickness of a gate oxide film (108). The gate oxide film (106) becomes thicker toward a side wall (112) of the STI oxide film (106) to prevent the leakage current and increase the gate breakdown voltage.

## Claims

### Claim 1

A method of manufacturing a semiconductor device comprising the steps of:
scraping an upper surface of a silicon substrate by an anisotropic-etching such that an upper surface of an element-isolating region filled with an oxide film is positioned higher than said upper surface of said silicon substrate;
forming a sacrifice oxide film on said upper surface of said silicon substrate by oxidizing said upper surface of said silicon substrate;
removing said sacrifice oxide film; and
forming a gate oxide film on said upper surface of said silicon substrate.

### Claim 2 (depends on 1)

The method according to claim 1, which further comprises the step of implanting oxygen ion into said upper surface of said silicon substrate.

### Claim 3 (depends on 1)

The method according to claim 1, wherein, in the step of scraping the upper surface of the silicon substrate, said silicon substrate is scraped such that the upper surface of the silicon substrate is gradually rising toward the element-isolating region.

### Claim 4 (depends on 1)

The method according to claim 1, wherein, in the step of forming the gate oxide film, said gate oxide film is formed such that a thickness thereof is gradually increasing toward the toward the element-isolating region.

### Claim 5 (depends on 1)

The method according to claim 1, wherein, in the step of forming the gate oxide film, said gate oxide film is formed such that an upper surface thereof is gradually rising toward the element-isolating region.

### Claim 6

A method of manufacturing a semiconductor device comprising the steps of:
forming a pad oxide film on a silicone substrate through thermal oxidation;
forming a mask film on the pad oxide film;
forming an opening in the mask film as an element-isolating region;
forming a trench in the opening;
forming a side-wall oxide film on a bottom surface and side surfaces of the trench through thermal oxidation;
filling the trench with an oxide film;
removing the mask film and the pad oxide film so that the oxide film is exposed;
scraping the silicon substrate so that the oxide film and the side-wall oxide film protrude above an upper surface of the silicon substrate;
forming a sacrifice oxide film on the silicon substrate;
removing the sacrifice oxide film; and
forming a gate oxide film on the silicon substrate.

### Claim 7 (depends on 6)

The method according to claim 6, further comprising the step of implanting oxygen ions into the silicon substrate.

### Claim 8 (depends on 6)

The method according to claim 6, wherein, in the step of scraping the silicon substrate, said silicon substrate is scraped such that the upper surface of the silicon substrate is gradually rising toward the side-wall oxide film.

### Claim 9 (depends on 6)

The method according to claim 6, wherein, in the step of forming the gate oxide film, said gate oxide film is formed such that a thickness thereof is gradually increasing toward the side-wall oxide film.

### Claim 10 (depends on 6)

The method according to claim 6, wherein, in the step of forming the gate oxide film, said gate oxide film is formed such that an upper surface thereof is gradually rising toward the side-wall oxide film.