# US 9,040,981 B2 · Semiconductor device

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- Number: US 9,040,981 B2
- Document ID: US9040981B2
- Status: Granted
- Kind: B2
- Application number: 13/738,484
- Filed: 2013-01-10
- Published: 2013-07-25
- Granted: 2015-05-26
- Earliest claimed: 2012-01-20
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Shunpei Yamazaki
- Web page: https://patentgrep.com/patent/US9040981B2

## CPC

- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 30/67: Thin-film transistors [TFT] {(Stacked nanowire, nanosheet or nanoribbon FETs H10D30/501)}
- H10D 30/6713: {characterised by the properties of the source or drain regions, e.g. compositions or sectional shapes}
- H10D 30/6739: {Conductor-insulator-semiconductor electrodes}
- 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 62/117: {Shapes of semiconductor bodies}
- H10D 62/126: {Top-view geometrical layouts of the regions or the junctions}
- H10D 62/235: {of IGFETs (IGFETs having buried channels H10D30/637)}
- H10D 62/80: characterised by the materials
- H10D 64/685: {being perpendicular to the channel plane}
- H10D 64/693: {the insulator comprising nitrogen, e.g. nitrides, oxynitrides or nitrogen-doped materials}
- H10D 86/423: {comprising semiconductor materials not belonging to the Group IV, e.g. InGaZnO}
- H10D 86/60: wherein the TFTs are in active matrices
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Provided is a transistor which has favorable transistor characteristics and includes an oxide semiconductor, and a highly reliable semiconductor device which includes the transistor including the oxide semiconductor. In the semiconductor device including the transistor in which an oxide semiconductor film, a gate insulating film, and a gate electrode are stacked in this order, a sidewall insulating film is formed along side surfaces and a top surface of the gate electrode, and the oxide semiconductor film is subjected to etching treatment so as to have a cross shape having different lengths in the channel length direction or to have a larger length than a source electrode and a drain electrode in the channel width direction. Further, the source electrode and the drain electrode are formed in contact with the oxide semiconductor film.

## Claims

### Claim 1

A semiconductor device comprising:
an oxide semiconductor film comprising:
a channel formation region;
a first region protruding from the channel formation region in a first channel width direction;
a second region protruding from the channel formation region in a second channel width direction opposite to the first channel width direction;
a source region; and
a drain region;
a gate electrode overlapping with the first region, the second region, and the channel formation region; and
an insulating film between the oxide semiconductor film and the gate electrode,
wherein the channel formation region is provided between the first region and the second region,
wherein the channel formation region is provided between the source region and the drain region in a channel length direction,
wherein a resistance in each of the source region and the drain region is lower than a resistance in the channel formation region, and
wherein the oxide semiconductor film has a cross shape.

### Claim 2 (depends on 1)

The semiconductor device according to claim 1, wherein the gate electrode is provided over the oxide semiconductor film.

### Claim 3 (depends on 1)

The semiconductor device according to claim 1, wherein the oxide semiconductor film comprises indium, zinc, and a metal element other than indium and zinc.

### Claim 4 (depends on 3)

The semiconductor device according to claim 3, wherein the metal element is gallium.

### Claim 5 (depends on 1)

The semiconductor device according to claim 1,
wherein the insulating film comprises:
a first insulating film comprising oxygen; and
a second insulating film comprising nitrogen between the first insulating film and the gate electrode.

### Claim 6 (depends on 1)

The semiconductor device according to claim 1,
wherein the source region and the drain region comprise an impurity, and
wherein the impurity is one or more selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, boron, aluminum, argon, helium, neon, indium, fluorine, chlorine, titanium, and zinc.

### Claim 7 (depends on 1)

The semiconductor device according to claim 1, wherein a concentration of copper in the oxide semiconductor film is lower than or equal to 1×1018 atoms/cm3.

### Claim 8 (depends on 1)

The semiconductor device according to claim 1, wherein a concentration of aluminum in the oxide semiconductor film is lower than or equal to 1×1018 atoms/cm3.

### Claim 9 (depends on 1)

The semiconductor device according to claim 1, wherein a concentration of chlorine in the oxide semiconductor film is lower than or equal to 2×1018 atoms/cm3.

### Claim 10

A semiconductor device comprising:
an oxide semiconductor film comprising:
a channel formation region;
a first region protruding from the channel formation region in a first channel width direction;
a second region protruding from the channel formation region in a second channel width direction opposite to the first channel width direction;
a source region; and
a drain region;
a first conductive film in contact with the source region;
a second conductive film in contact with the drain region;
a gate electrode overlapping with the first region, the second region, and the channel formation region; and
an insulating film between the oxide semiconductor film and the gate electrode,
wherein the channel formation region is provided between the first region and the second region,
wherein the channel formation region is provided between the source region and the drain region in a channel length direction,
wherein a resistance in each of the source region and the drain region is lower than a resistance in the channel formation region,
wherein the channel formation region, the source region and the drain region are provided between the first conductive film and the second conductive film in the channel length direction, and
wherein the oxide semiconductor film has a cross shape.

### Claim 11 (depends on 10)

The semiconductor device according to claim 10, wherein the gate electrode is provided over the oxide semiconductor film.

### Claim 12 (depends on 10)

The semiconductor device according to claim 10, wherein the oxide semiconductor film comprises indium, zinc, and a metal element other than indium and zinc.

### Claim 13 (depends on 12)

The semiconductor device according to claim 12, wherein the metal element is gallium.

### Claim 14 (depends on 10)

The semiconductor device according to claim 10,
wherein the insulating film comprises:
a first insulating film comprising oxygen; and
a second insulating film comprising nitrogen between the first insulating film and the gate electrode.

### Claim 15 (depends on 10)

The semiconductor device according to claim 10, wherein a concentration of copper in the oxide semiconductor film is lower than or equal to 1×1018 atoms/cm3.

### Claim 16 (depends on 10)

The semiconductor device according to claim 10, wherein a concentration of aluminum in the oxide semiconductor film is lower than or equal to 1×1018 atoms/cm3.

### Claim 17 (depends on 10)

The semiconductor device according to claim 10, wherein a concentration of chlorine in the oxide semiconductor film is lower than or equal to 2×1018 atoms/cm3.