# US 10,483,354 B2 · Nitride semiconductor device

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- Number: US 10,483,354 B2
- Document ID: US10483354B2
- Status: Granted
- Kind: B2
- Application number: 16/118,573
- Filed: 2018-08-31
- Published: 2019-08-01
- Granted: 2019-11-19
- Earliest claimed: 2018-01-30
- Assignees: Kabushiki Kaisha Toshiba
- Applicants: Kabushiki Kaisha Toshiba
- Inventors: Kenjiro Uesugi; Shigeya Kimura; Toshiki Hikosaka
- Web page: https://patentgrep.com/patent/US10483354B2

## CPC

- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 30/4732: {using Group III-V semiconductor material}
- H10D 62/824: comprising only Group III-V materials heterojunctions, e.g. GaN/AlGaN heterojunctions
- H10D 62/852: being Group III-V materials comprising three or more elements, e.g. AlGaN or InAsSbP
- H10D 62/854: further characterised by the dopants
- H10D 64/251: {Source or drain electrodes for field-effect devices}
- H10D 64/511: {for IGFETs}
- H10D 64/513: {within recesses in the substrate, e.g. trench gates, groove gates or buried gates}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

In one embodiment, a nitride semiconductor device is provided with a first semiconductor layer that is a layer of Alx1Ga(1-x1)N (0<x1≤1), a second semiconductor layer that is on the first semiconductor layer and is a layer of a nitride semiconductor Iny2Alx2Ga(1-x2-y2)N (0<x2<1, 0<y2<1, 0<x2+y2≤1) containing indium, a third semiconductor layer that is on the second semiconductor layer and is a layer of Alx3Ga(1-x3)N (0≤x3<1), and a fourth semiconductor layer that is on the third semiconductor layer and is an layer of Iny4Alx4Ga(1-x4-y4)N (0<x4<1, 0≤y4<1, 0<x4+y4≤1).

## Claims

### Claim 1

A nitride semiconductor device comprising:
(i) a first semiconductor layer, which satisfies Alx1Ga(1-x1)N,
wherein x1 is greater than 0 and less than or equal to 1;
(ii) a second semiconductor layer, which satisfies Iny2Alx2Ga(1-x2-y2)N,
wherein x2 is greater than 0 and less than 1,
wherein y2 is greater than 0 and less than 1, and
wherein x2+y2 is greater than 0 and less than or equal to 1;
(iii) a third semiconductor layer, which satisfies Alx3Ga(1-x3)N,
wherein x3 is greater than or equal to 0 and less than 1; and
(iv) a fourth semiconductor layer, which satisfies Iny4Alx4Ga(1-x4-y4)N,
wherein x4 is greater than 0 and less than 1,
wherein y4 is greater than or equal to 0 and less than 1, and
wherein x4+y4 is greater than 0 and less than or equal to 1,
wherein the second semiconductor layer is disposed on the first semiconductor layer,
wherein the third semiconductor layer is disposed on the second semiconductor layer, and
wherein the fourth semiconductor layer is disposed on the third semiconductor layer.

### Claim 2 (depends on 1)

The nitride semiconductor device of claim 1, wherein a lattice constant of the third semiconductor layer is larger than a lattice constant of the second semiconductor layer.

### Claim 3 (depends on 1)

The nitride semiconductor device of claim 1, wherein sums of a spontaneous polarization and a piezo polarization in the respective semiconductor layers are smaller in the order of: the first semiconductor layer, the second semiconductor layer, the third semiconductor layer, and the fourth semiconductor layer.

### Claim 4 (depends on 1)

The nitride semiconductor device of claim 1, wherein x1, x2 and y2 satisfy y2≤0.224*x2+0.131 and x2−x1≤1.44*y2.

### Claim 5 (depends on 1)

The nitride semiconductor device of claim 1, wherein x1, x2 and y2 satisfy y2≤0.224*x2 and x2−x1≤−0.143*y2.

### Claim 6 (depends on 1)

The nitride semiconductor device of claim 1, wherein an atomic ratio of x2 to a total of group III atoms comprised in the second semiconductor layer is not less than 0.1.

### Claim 7 (depends on 1)

The nitride semiconductor device of claim 1, wherein an atomic ratio of x2 to a total of group III atoms comprised in the second semiconductor layer is not less than 0.15.

### Claim 8 (depends on 1)

The nitride semiconductor device of claim 1, wherein a thickness of the third semiconductor layer is not less than 10 nm and not more than 200 nm.

### Claim 9 (depends on 1)

The nitride semiconductor device of claim 1, wherein a thickness of the third semiconductor layer is not less than 20 nm and not more than 100 nm.

### Claim 10 (depends on 1)

The nitride semiconductor device of claim 1, further comprising:
a source electrode disposed on the fourth semiconductor layer;
a drain electrode disposed on the fourth semiconductor layer; and
a gate electrode disposed between the source electrode and the drain electrode.

### Claim 11 (depends on 10)

The nitride semiconductor device of claim 10, further comprising:
an insulating layer disposed on the fourth semiconductor layer, and between the source electrode and the drain electrode;
wherein the drain electrode is disposed on the fourth semiconductor layer, and
wherein the gate electrode is disposed on the insulating layer.

### Claim 12 (depends on 11)

The nitride semiconductor device of claim 11, wherein an atomic ratio of x4 of a portion of the fourth semiconductor layer, wherein the portion is below the gate electrode, to a total of group III atoms comprised in the fourth semiconductor layer is not more than 0.2.

### Claim 13 (depends on 12)

The nitride semiconductor device of claim 12, wherein a thickness of a portion of the fourth semiconductor layer, wherein the portion is below the gate electrode, is not less than 0 nm and not more than 5 nm.

### Claim 14 (depends on 10)

The nitride semiconductor device of claim 10, wherein an atomic ratio of x4 of the fourth semiconductor layer, other than a portion below the gate electrode, to a total of group III atoms comprised in the fourth semiconductor layer is not less than 0.15.

### Claim 15 (depends on 14)

The nitride semiconductor device of claim 14, wherein a thickness of the fourth semiconductor layer, other than the portion below the gate electrode, is not less than 20 nm and not more than 100 nm.