# US 2017/0256646 A1 · Method for manufacturing semiconductor device

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- Number: US 2017/0256646 A1
- Document ID: US20170256646A1
- Status: Published application
- Kind: A1
- Application number: 15/601,301
- Filed: 2017-05-22
- Published: 2017-09-07
- Earliest claimed: 2011-01-12
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Shunpei YAMAZAKI
- Web page: https://patentgrep.com/patent/US20170256646A1

## CPC

- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 30/6729: {characterised by the electrodes}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A transistor having an oxide semiconductor film in a channel formation region and a manufacturing method thereof are disclosed. The transistor is formed by the steps of: forming a base insulating over a substrate; forming an oxide semiconductor film over the base insulating film; forming a conductive film over the oxide semiconductor film; processing the conductive film to form a source electrode and a drain electrode; processing the oxide semiconductor film; forming a gate insulating film over the source electrode, the drain electrode, and the oxide semiconductor film; and forming a gate electrode over the gate insulating film. The aforementioned manufacturing method allows the formation of a transistor in which a side surface of the oxide semiconductor film is not in direct contact with bottom surfaces of the source electrode and the drain electrode, which contributes to the extremely small leak current of the transistor.

## Claims

### Claim 1

A method for manufacturing a semiconductor device comprising a transistor, the method comprising the steps of:
forming a first oxide semiconductor film over a substrate;
forming a conductive film over the first oxide semiconductor film;
processing the conductive film by removing a part of the conductive film which overlaps a part of the first oxide semiconductor film; and
processing the first oxide semiconductor film via another step after processing the conductive film,
wherein the transistor is formed by using the processed first oxide semiconductor film, and
wherein a channel formation region of the transistor is formed in the part of the first oxide semiconductor film.

### Claim 2 (depends on 1)

The method according to claim 1,
wherein the another step is a step of forming a resist mask over the first oxide semiconductor film.

### Claim 3 (depends on 1)

The method according to claim 1,
wherein the conductive film comprises W.

### Claim 4 (depends on 1)

The method according to claim 1, further comprising the step of conducting plasma treatment after processing the first oxide semiconductor film.

### Claim 5 (depends on 1)

The method according to claim 1, further comprising the step of heating the substrate after forming the first oxide semiconductor film and before forming the conductive film.

### Claim 6 (depends on 1)

The method according to claim 1, further comprising the step of heating the substrate after forming the conductive film and before processing the conductive film.

### Claim 7 (depends on 1)

The method according to claim 1, further comprising the step of forming a second oxide semiconductor film over and in contact with the first oxide semiconductor film.

### Claim 8 (depends on 1)

The method according to claim 1,
wherein the transistor comprises a gate electrode over the processed first oxide semiconductor film.

### Claim 9 (depends on 1)

The method according to claim 1,
wherein a source electrode and a drain electrode are formed by the step of processing the conductive film.

### Claim 10

A method for manufacturing a semiconductor device comprising a transistor, the method comprising the steps of:
forming a first oxide semiconductor film over a substrate;
forming a conductive film over the first oxide semiconductor film;
processing the conductive film by removing a part of the conductive film which overlaps a part of the first oxide semiconductor film;
forming a resist mask over the first oxide semiconductor film after processing the conductive film; and
processing the first oxide semiconductor film after forming the resist mask,
wherein the transistor is formed by using the processed first oxide semiconductor film, and
wherein a channel formation region of the transistor is formed in the part of the first oxide semiconductor film.

### Claim 11 (depends on 10)

The method according to claim 10, further comprising the step of removing the resist mask after processing the first oxide semiconductor film.

### Claim 12 (depends on 10)

The method according to claim 10,
wherein the conductive film comprises W.

### Claim 13 (depends on 10)

The method according to claim 10, further comprising the step of conducting plasma treatment after processing the first oxide semiconductor film.

### Claim 14 (depends on 10)

The method according to claim 10, further comprising the step of heating the substrate after forming the first oxide semiconductor film and before forming the conductive film.

### Claim 15 (depends on 10)

The method according to claim 10, further comprising the step of heating the substrate after forming the conductive film and before processing the conductive film.

### Claim 16 (depends on 10)

The method according to claim 10, further comprising the step of forming a second oxide semiconductor film over and in contact with the first oxide semiconductor film.

### Claim 17 (depends on 10)

The method according to claim 10,
wherein the transistor comprises a gate electrode over the processed first oxide semiconductor film.

### Claim 18 (depends on 10)

The method according to claim 10,
wherein a source electrode and a drain electrode are formed by the step of processing the conductive film.