# US 2014/0191230 A1 · Semiconductor device

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- Number: US 2014/0191230 A1
- Document ID: US20140191230A1
- Status: Published application
- Kind: A1
- Application number: 14/202,737
- Filed: 2014-03-10
- Published: 2014-07-10
- Earliest claimed: 2011-10-27
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Tatsuya HONDA; Masashi TSUBUKU; Yusuke NONAKA; Takashi SHIMAZU
- Web page: https://patentgrep.com/patent/US20140191230A1

## CPC

- H10D 30/6756: {Amorphous oxide semiconductors}
- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 30/6757: {characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A semiconductor device includes a base insulating film including silicon, an oxide semiconductor film over the base insulating film, a gate insulating film over the oxide semiconductor film, a gate electrode which is in contact with the gate insulating film and overlaps with at least the oxide semiconductor film, and a source electrode and a drain electrode electrically connected to the oxide semiconductor film. The oxide semiconductor film includes a region in which a concentration of silicon distributed from the interface with the base insulating film toward an inside of the oxide semiconductor film is lower than or equal to 1.0 at. %. A crystal portion is included at least in the region.

## Claims

### Claim 1

(canceled)

### Claim 2

A semiconductor device comprising:
an insulating film comprising silicon;
an oxide semiconductor film over the insulating film;
a gate insulating film over the oxide semiconductor film;
a gate electrode over the gate insulating film;
a source electrode electrically connected to the oxide semiconductor film; and
a drain electrode electrically connected to the oxide semiconductor film,
wherein the oxide semiconductor film comprises:
a first region in contact with the insulating film; and
a second region over the first region,
wherein a concentration of silicon in the first region is lower than or equal to 1.0 at. %,
wherein the first region comprises a crystal portion, and
wherein a c-axis in the crystal portion is aligned in a direction substantially parallel to a normal vector of a surface of the insulating film.

### Claim 3 (depends on 2)

The semiconductor device according to claim 2, wherein the insulating film further comprises oxygen.

### Claim 4 (depends on 2)

The semiconductor device according to claim 2, wherein the oxide semiconductor film comprises a second crystal portion in the second region.

### Claim 5 (depends on 2)

The semiconductor device according to claim 2, wherein an average surface roughness of the surface of the insulating film is less than or equal to 0.15 nm.

### Claim 6 (depends on 2)

The semiconductor device according to claim 2, wherein an end portion of the oxide semiconductor film is tapered at an angle of 20° to 50°.

### Claim 7 (depends on 2)

The semiconductor device according to claim 2, wherein the concentration of silicon in the first region is lower than or equal to 0.1 at. %.

### Claim 8

A semiconductor device comprising:
an insulating film comprising silicon;
an oxide semiconductor film over the insulating film;
a gate insulating film over the oxide semiconductor film;
a gate electrode over the gate insulating film;
a source electrode electrically connected to the oxide semiconductor film; and
a drain electrode electrically connected to the oxide semiconductor film,
wherein the oxide semiconductor film comprises:
a first region in contact with the insulating film; and
a second region over the first region,
wherein a concentration of silicon in the first region is lower than or equal to 1.0 at. %,
wherein the first region comprises a crystal portion,
wherein a c-axis in the crystal portion is aligned in a direction substantially parallel to a normal vector of a surface of the insulating film, and
wherein a concentration of carbon in the first region is lower than or equal to 1.0×1020 atoms/cm3.

### Claim 9 (depends on 8)

The semiconductor device according to claim 8, wherein the insulating film further comprises oxygen.

### Claim 10 (depends on 8)

The semiconductor device according to claim 8, wherein the oxide semiconductor film comprises a second crystal portion in the second region.

### Claim 11 (depends on 8)

The semiconductor device according to claim 8, wherein an average surface roughness of the surface of the insulating film is less than or equal to 0.15 nm.

### Claim 12 (depends on 8)

The semiconductor device according to claim 8, wherein an end portion of the oxide semiconductor film is tapered at an angle of 20° to 50°.

### Claim 13 (depends on 8)

The semiconductor device according to claim 8, wherein the concentration of silicon in the first region is lower than or equal to 0.1 at. %.

### Claim 14

A semiconductor device comprising:
an insulating film comprising silicon;
an oxide semiconductor film over the insulating film;
a gate insulating film over the oxide semiconductor film;
a gate electrode over the gate insulating film;
a source electrode electrically connected to the oxide semiconductor film; and
a drain electrode electrically connected to the oxide semiconductor film,
wherein the oxide semiconductor film comprises:
a first region in contact with the insulating film; and
a second region over the first region,
wherein a concentration of silicon in the first region is lower than or equal to 1.0 at. %,
wherein the first region comprises a crystal portion,
wherein a c-axis in the crystal portion is aligned in a direction substantially parallel to a normal vector of a surface of the insulating film,
wherein a concentration of carbon in the first region is lower than or equal to 1.0×1020 atoms/cm3, and
wherein a thickness of the first region is less than or equal to 5 nm.

### Claim 15 (depends on 14)

The semiconductor device according to claim 14, wherein the insulating film further comprises oxygen.

### Claim 16 (depends on 14)

The semiconductor device according to claim 14, wherein the oxide semiconductor film comprises a second crystal portion in the second region.

### Claim 17 (depends on 14)

The semiconductor device according to claim 14, wherein an average surface roughness of the surface of the insulating film is less than or equal to 0.15 nm.

### Claim 18 (depends on 14)

The semiconductor device according to claim 14, wherein an end portion of the oxide semiconductor film is tapered at an angle of 20° to 50°.

### Claim 19 (depends on 14)

The semiconductor device according to claim 14, wherein the concentration of silicon in the first region is lower than or equal to 0.1 at. %.