# US 2014/0151685 A1 · Semiconductor device

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- Number: US 2014/0151685 A1
- Document ID: US20140151685A1
- Status: Published application
- Kind: A1
- Application number: 14/089,085
- Filed: 2013-11-25
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Hajime TOKUNAGA; Junichi KOEZUKA; Kenichi OKAZAKI; Shunpei YAMAZAKI
- Web page: https://patentgrep.com/patent/US20140151685A1

## CPC

- 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 30/6704: {having supplementary regions or layers in the thin films or in the insulated bulk substrates for controlling properties of the device}
- H10D 30/6734: {having gate electrodes arranged on both top and bottom sides of the channel, e.g. dual-gate TFTs}
- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 30/6756: {Amorphous oxide semiconductors}
- H10D 62/402: {Amorphous materials}
- H10D 62/80: characterised by the materials
- H10D 62/86: being Group II-VI materials, e.g. ZnO
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A highly reliable semiconductor device having stable electrical characteristics is provided. Oxide films each containing one or more kinds of metal elements included in an oxide semiconductor film are formed in contact with an upper side and a lower side of the oxide semiconductor film where a channel is formed, whereby interface states are not easily generated at an upper interface and a lower interface of the oxide semiconductor film. A material which has a lower electron affinity than the oxide semiconductor film is used for the oxide films in contact with the oxide semiconductor film, whereby electrons flowing in the channel hardly move in the oxide films and mainly move in the oxide semiconductor film. Thus, even when an interface state exists between the oxide film and an insulating film formed on the outside of the oxide film, the state hardly influences the movement of electrons.

## Claims

### Claim 1

A semiconductor device comprising:
a first electrode;
a first insulating film over the first electrode;
an oxide semiconductor film comprising gallium over the first insulating film;
a first oxide film comprising gallium over and in contact with the oxide semiconductor film;
a second electrode over the first oxide film;
a third electrode over the first oxide film; and
a second oxide film comprising gallium over and in contact with the first oxide film, the second electrode, and the third electrode.

### Claim 2 (depends on 1)

The semiconductor device according to claim 1, wherein the oxide semiconductor film further comprises indium and zinc.

### Claim 3 (depends on 1)

The semiconductor device according to claim 1, wherein each of the first oxide film and the second oxide film further comprises indium and zinc.

### Claim 4 (depends on 1)

The semiconductor device according to claim 1, wherein the oxide semiconductor film, the first oxide film, and the second oxide film each comprise same metal elements.

### Claim 5 (depends on 1)

The semiconductor device according to claim 1,
wherein electron affinity of the second oxide film is the same as electron affinity of the first oxide film, and
wherein the electron affinity of the second oxide film is lower than electron affinity of the oxide semiconductor film.

### Claim 6 (depends on 1)

The semiconductor device according to claim 1,
wherein electron affinity of the second oxide film is lower than electron affinity of the first oxide film, and
wherein the electron affinity of the second oxide film is lower than electron affinity of the oxide semiconductor film.

### Claim 7 (depends on 1)

The semiconductor device according to claim 1, further comprising a second insulating film over and in contact with the second oxide film,
wherein the second insulating film contains excess oxygen.

### Claim 8 (depends on 7)

The semiconductor device according to claim 7, wherein the second insulating film is a stack of an oxide insulating film and a nitride insulating film.

### Claim 9

A semiconductor device comprising:
a first electrode;
a first insulating film over the first electrode;
a first oxide film comprising gallium over the first insulating film;
an oxide semiconductor film comprising gallium over the first oxide film;
a second oxide film comprising gallium over and in contact with the oxide semiconductor film;
a second electrode over the second oxide film;
a third electrode over the second oxide film; and
a third oxide film comprising gallium over and in contact with the second oxide film, the second electrode, and the third electrode.

### Claim 10 (depends on 9)

The semiconductor device according to claim 9, wherein the oxide semiconductor film further comprises indium and zinc.

### Claim 11 (depends on 9)

The semiconductor device according to claim 9, wherein each of the first oxide film, the second oxide film, and the third oxide film further comprises indium and zinc.

### Claim 12 (depends on 9)

The semiconductor device according to claim 9, wherein the oxide semiconductor film, the first oxide film, the second oxide film, and the third oxide film each comprise same metal elements.

### Claim 13 (depends on 9)

The semiconductor device according to claim 9,
wherein electron affinity of the third oxide film is the same as electron affinity of the first oxide film and electron affinity of the second oxide film, and
wherein the electron affinity of the third oxide film is lower than electron affinity of the oxide semiconductor film.

### Claim 14 (depends on 9)

The semiconductor device according to claim 9,
wherein electron affinity of the third oxide film is lower than electron affinity of the first oxide film and electron affinity of the second oxide film, and
wherein the electron affinity of the first oxide film and the electron affinity of the second oxide film are lower than electron affinity of the oxide semiconductor film.

### Claim 15 (depends on 9)

The semiconductor device according to claim 9,
wherein electron affinity of the third oxide film is the same as electron affinity of the second oxide film,
wherein the electron affinity of the third oxide film is higher than electron affinity of the first oxide film, and
wherein the electron affinity of the third oxide film is lower than electron affinity of the oxide semiconductor film.

### Claim 16 (depends on 9)

The semiconductor device according to claim 9,
wherein electron affinity of the third oxide film is the same as electron affinity of the first oxide film,
wherein the electron affinity of the third oxide film is lower than electron affinity of the second oxide film, and
wherein the electron affinity of the third oxide film is lower than electron affinity of the oxide semiconductor film.

### Claim 17 (depends on 9)

The semiconductor device according to claim 9, further comprising a second insulating film over and in contact with the third oxide film,
wherein the second insulating film contains excess oxygen.

### Claim 18 (depends on 17)

The semiconductor device according to claim 17, wherein the second insulating film is a stack of an oxide insulating film and a nitride insulating film.