# US 9,040,984 B2 · Transistor with ZrO or HfO gate insulator sandwiched between two SiO or AIO gate insulators over an oxide semiconductor film

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- Number: US 9,040,984 B2
- Document ID: US9040984B2
- Status: Granted
- Kind: B2
- Application number: 14/077,371
- Filed: 2013-11-12
- Published: 2014-05-15
- Granted: 2015-05-26
- Earliest claimed: 2012-11-15
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Hirokazu Watanabe; Shinji Ohno
- Web page: https://patentgrep.com/patent/US9040984B2

## CPC

- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 30/6739: {Conductor-insulator-semiconductor electrodes}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

To provide a semiconductor device which includes a gate insulating film with high withstand voltage and thus can have high reliability. The semiconductor device includes an oxide semiconductor film over an insulating surface; a pair of first conductive films over the oxide semiconductor film; a first insulating film, a second insulating film, and a third insulating film which are stacked in this order over the oxide semiconductor film and the pair of first conductive films; and a second conductive film overlapping with the oxide semiconductor film over the first to third insulating films. The first insulating film and the third insulating film contain silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, aluminum oxide, or aluminum oxynitride. The second insulating film contains gallium oxide, zirconium oxide, or hafnium oxide.

## Claims

### Claim 1

A semiconductor device comprising a transistor comprising:
an oxide semiconductor film;
a first conductive film electrically connected to the oxide semiconductor film;
a second conductive film electrically connected to the oxide semiconductor film;
a first insulating film over the oxide semiconductor film, the first conductive film, and the second conductive film;
a second insulating film over the first insulating film;
a third insulating film over the second insulating film; and
a third conductive film as a gate electrode of the transistor over the third insulating film,
wherein the first insulating film and the third insulating film each comprise an oxide including silicon or an oxide including aluminum, and
wherein the second insulating film comprises an oxide including gallium, an oxide including zirconium, or an oxide including hafnium.

### Claim 2 (depends on 1)

The semiconductor device according to claim 1,
wherein the first insulating film and the third insulating film each comprise silicon oxide, and
wherein the second insulating film comprises hafnium oxide.

### Claim 3 (depends on 1)

The semiconductor device according to claim 1,
wherein the oxide semiconductor film comprises at least one of indium, gallium, and zinc.

### Claim 4 (depends on 1)

The semiconductor device according to claim 1,
wherein the first conductive film and the second conductive film each comprise at least one of molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, scandium, and niobium.

### Claim 5 (depends on 1)

The semiconductor device according to claim 1,
wherein the third conductive film comprises at least one of aluminum, titanium, chromium, cobalt, nickel, copper, yttrium, zirconium, molybdenum, ruthenium, silver, tantalum, and tungsten.

### Claim 6 (depends on 1)

The semiconductor device according to claim 1,
wherein the first conductive film and the second conductive film are over the oxide semiconductor film.

### Claim 7 (depends on 1)

The semiconductor device according to claim 1, further comprising a fourth conductive film under the oxide semiconductor film with a fourth insulating film interposed between the oxide semiconductor film and the fourth conductive film.

### Claim 8

A semiconductor device comprising a transistor comprising:
a first conductive film as a gate electrode of the transistor;
a first insulating film over the first conductive film;
a second insulating film over the first insulating film;
a third insulating film over the second insulating film;
an oxide semiconductor film over the third insulating film;
a second conductive film electrically connected to the oxide semiconductor film; and
a third conductive film electrically connected to the oxide semiconductor film,
wherein the first insulating film and the third insulating film each comprise an oxide including silicon or an oxide including aluminum, and
wherein the second insulating film comprises an oxide including gallium, an oxide including zirconium, or an oxide including hafnium.

### Claim 9 (depends on 8)

The semiconductor device according to claim 8,
wherein the first insulating film and the third insulating film each comprise silicon oxide, and
wherein the second insulating film comprises hafnium oxide.

### Claim 10 (depends on 8)

The semiconductor device according to claim 8,
wherein the oxide semiconductor film comprises at least one of indium, gallium, and zinc.

### Claim 11 (depends on 8)

The semiconductor device according to claim 8,
wherein the first conductive film and the second conductive film each comprise at least one of molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, scandium, and niobium.

### Claim 12 (depends on 8)

The semiconductor device according to claim 8,
wherein the third conductive film comprises at least one of aluminum, titanium, chromium, cobalt, nickel, copper, yttrium, zirconium, molybdenum, ruthenium, silver, tantalum, and tungsten.

### Claim 13 (depends on 8)

The semiconductor device according to claim 8,
wherein the first conductive film and the second conductive film are over the oxide semiconductor film.

### Claim 14

A semiconductor device comprising a transistor comprising:
an oxide semiconductor film;
a first conductive film electrically connected to the oxide semiconductor film;
a second conductive film electrically connected to the oxide semiconductor film;
a first insulating film over the oxide semiconductor film, the first conductive film, and the second conductive film, the first insulating film comprising silicon oxide;
a second insulating film over the first insulating film, the second insulating film comprising hafnium oxide;
a third insulating film over the second insulating film, the third insulating film comprising aluminum oxide; and
a third conductive film as a gate electrode of the transistor over the third insulating film.

### Claim 15 (depends on 14)

The semiconductor device according to claim 14,
wherein the oxide semiconductor film comprises at least one of indium, gallium, and zinc.

### Claim 16 (depends on 14)

The semiconductor device according to claim 14,
wherein the first conductive film and the second conductive film each comprise at least one of molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, scandium, and niobium.

### Claim 17 (depends on 14)

The semiconductor device according to claim 14,
wherein the first conductive film and the second conductive film are over the oxide semiconductor film.