# US 8,785,990 B2 · Semiconductor device including first and second or drain electrodes and manufacturing method thereof

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- Number: US 8,785,990 B2
- Document ID: US8785990B2
- Status: Granted
- Kind: B2
- Application number: 13/343,474
- Filed: 2012-01-04
- Published: 2012-04-26
- Granted: 2014-07-22
- Earliest claimed: 2005-10-14
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Tatsuya Honda
- Inventors: Tatsuya Honda
- Web page: https://patentgrep.com/patent/US8785990B2

## CPC

- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 30/6729: {characterised by the electrodes}
- H10K 10/84: Ohmic electrodes, e.g. source or drain electrodes
- H10K 77/111: {Flexible substrates}
- H10K 2102/311: {Flexible OLED}
- Y02E 10/549: Organic PV cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

An object is to obtain a semiconductor device with improved characteristics by reducing contact resistance of a semiconductor film with electrodes or wirings, and improving coverage of the semiconductor film and the electrodes or wirings. The present invention relates to a semiconductor device including a gate electrode over a substrate, a gate insulating film over the gate electrode, a first source or drain electrode over the gate insulating film, an island-shaped semiconductor film over the first source or drain electrode, and a second source or drain electrode over the island-shaped semiconductor film and the first source or drain electrode. Further, the second source or drain electrode is in contact with the first source or drain electrode, and the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode. Moreover, the present invention relates to a manufacturing method of the semiconductor device.

## Claims

### Claim 1

A semiconductor device comprising:
a gate electrode over a substrate;
a gate insulating film over the gate electrode;
a first source or drain electrode over the gate insulating film;
an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film; and
a second source or drain electrode over the island-shaped semiconductor film and the first source or drain electrode,
wherein a part of the second source or drain electrode is formed over and in direct contact with the first source or drain electrode,
wherein the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode,
wherein a thickness of the second source or drain electrode is larger than a thickness of the first source or drain electrode, and
wherein the second source or drain electrode covers an edge of the island-shaped semiconductor film.

### Claim 2 (depends on 1)

The semiconductor device according to claim 1, wherein the island-shaped semiconductor film is one selected from a group consisting of an indium oxide film, an indium phosphorus film and an indium nitride film.

### Claim 3 (depends on 1)

The semiconductor device according to claim 1, wherein the first source or drain electrode is a titanium film.

### Claim 4 (depends on 1)

The semiconductor device according to claim 1, wherein the gate electrode and the first source or drain electrode are formed of a same material.

### Claim 5 (depends on 1)

The semiconductor device according to claim 1, wherein the gate electrode, the first source or drain electrode, and the second source or drain electrode are formed of a same material.

### Claim 6

A semiconductor device comprising:
a gate electrode over a substrate;
a gate insulating film over the gate electrode;
a first source or drain electrode over the gate insulating film;
an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film;
an island-shaped impurity semiconductor film comprising an impurity imparting one conductivity type over the island-shaped semiconductor film; and
a second source or drain electrode over the island-shaped semiconductor film, the island-shaped impurity semiconductor film, and the first source or drain electrode,
wherein a part of the second source or drain electrode is formed over and in direct contact with the first source or drain electrode,
wherein the island-shaped semiconductor film and the island-shaped impurity semiconductor film are sandwiched between the first source or drain electrode and the second source or drain electrode,
wherein a thickness of the second source or drain electrode is larger than a thickness of the first source or drain electrode, and
wherein the second source or drain electrode covers an edge of the island-shaped semiconductor film.

### Claim 7 (depends on 6)

The semiconductor device according to claim 6, wherein the island-shaped semiconductor film is one selected from a group consisting of an indium oxide film, an indium phosphorus film and an indium nitride film.

### Claim 8 (depends on 6)

The semiconductor device according to claim 6, wherein the first source or drain electrode is a titanium film.

### Claim 9 (depends on 6)

The semiconductor device according to claim 6, wherein the gate electrode and the first source or drain electrode are formed of a same material.

### Claim 10 (depends on 6)

The semiconductor device according to claim 6, wherein the gate electrode, the first source or drain electrode, and the second source or drain electrode are formed of a same material.

### Claim 11

A manufacturing method of a semiconductor device comprising the steps of:
forming a gate electrode over a substrate;
forming a gate insulating film over the gate electrode;
forming a first source or drain electrode over the gate insulating film;
forming an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film; and
forming a second source or drain electrode over the first source or drain electrode and the island-shaped semiconductor film,
wherein a part of the second source or drain electrode is formed over and in direct contact with the first source or drain electrode,
wherein the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode,
wherein a thickness of the second source or drain electrode is larger than a thickness of the first source or drain electrode; and
wherein the second source or drain electrode covers an edge of the island-shaped semiconductor film.

### Claim 12

A manufacturing method of a semiconductor device comprising the steps of:
forming a first conductive film over a substrate;
forming a gate electrode using the first conductive film;
forming a gate insulating film over the gate electrode;
forming a second conductive film over the gate insulating film;
forming a first source or drain electrode using the second conductive film;
forming a semiconductor film over the first source or drain electrode;
forming an island-shaped semiconductor film including a channel forming region by patterning the semiconductor film;
forming a third conductive film over the first source or drain electrode and the island-shaped semiconductor film; and
forming a second source or drain electrode by patterning the third conductive film,
wherein a part of the second source or drain electrode is formed over and in direct contact with the first source or drain electrode,
wherein the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode,
wherein a thickness of the second source or drain electrode is larger than a thickness of the first source or drain electrode, and
wherein the second source or drain electrode covers an edge of the island-shaped semiconductor film.

### Claim 13 (depends on 12)

The manufacturing method of a semiconductor device according to claim 12, wherein the first source or drain electrode is a titanium film.

### Claim 14 (depends on 12)

The manufacturing method of a semiconductor device according to claim 12, wherein the gate electrode and the first source or drain electrode are formed of a same material.

### Claim 15 (depends on 12)

The manufacturing method of a semiconductor device according to claim 12, wherein the gate electrode, the first source or drain electrode, and the second source or drain electrode are formed of a same material.

### Claim 16

A manufacturing method of a semiconductor device comprising the steps of:
forming a gate electrode over a substrate;
forming a gate insulating film over the gate electrode;
forming a first source or drain electrode over the gate insulating film;
forming an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film;
forming an island-shaped impurity semiconductor film added with an impurity imparting one conductivity type over the island-shaped semiconductor film; and
forming a second source or drain electrode over the first source or drain electrode, the island-shaped semiconductor film, and the island-shaped impurity semiconductor film,
wherein a part of the second source or drain electrode is formed over and in direct contact with the first source or drain electrode,
wherein the island-shaped semiconductor film and the island-shaped impurity semiconductor film are sandwiched between the first source or drain electrode and the second source or drain electrode,
wherein a thickness of the second source or drain electrode is larger than a thickness of the first source or drain electrode, and
wherein the second source or drain electrode covers an edge of the island-shaped semiconductor film.

### Claim 17 (depends on 16)

The manufacturing method of a semiconductor device according to claim 16, wherein the first source or drain electrode is a titanium film.

### Claim 18 (depends on 16)

The manufacturing method of a semiconductor device according to claim 16, wherein the gate electrode and the first source or drain electrode are formed of a same material.

### Claim 19 (depends on 16)

The manufacturing method of a semiconductor device according to claim 16, wherein the gate electrode, the first source or drain electrode, and the second source or drain electrode are formed of a same material.