# US 2021/0280467 A1 · Semiconductor substrate, method for manufacturing semiconductor substrate and method for manufacturing semiconductor device

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- Number: US 2021/0280467 A1
- Document ID: US20210280467A1
- Status: Published application
- Kind: A1
- Application number: 17/330,369
- Filed: 2021-05-25
- Published: 2021-09-09
- Earliest claimed: 2018-12-10
- Assignees: Filnex Inc.
- Applicants: Filnex Inc.
- Inventors: Mitsuhiko OGIHARA
- Web page: https://patentgrep.com/patent/US20210280467A1

## CPC

- H10P 50/646: {of Group III-V materials}
- H10P 95/11: {Separation of active layers from substrates}
- H10P 50/246: {of Group III-V materials}
- H10P 72/74: {using temporarily an auxiliary support}
- H10P 90/00: Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement
- H10P 14/2909: {Phosphides}
- H10P 14/2911: {Arsenides}
- H10P 14/3221: {Arsenides}
- H10P 14/3248: {consisting of two layers}
- H10P 14/3418: {Phosphides}
- H10P 14/3421: {Arsenides}
- H10P 72/7432: {used in a transfer process involving transfer directly from an origin substrate to a target substrate without use of an intermediate handle substrate}
- H10P 72/7434: {used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

To prevent the surface of a base substrate and the bottom surface of a separated semiconductor epitaxial layer from being bonded to each other even after a removal layer is removed, the semiconductor substrate includes a base substrate, a first removal layer provided on the base substrate, a second removal layer provided above the first removal layer, and a semiconductor epitaxial layer provided above the second removal layer, and an etching rate of the second removal layer for a predetermined etching material is larger than the etching rate of the first removal layer for the predetermined etching material.

## Claims

### Claim 1

A semiconductor substrate comprising:
a base substrate;
a first removal layer that is provided on the base substrate and composed of AlxGa1-xAs (0.6<x≤0.8);
a second removal layer that is provided above the first removal layer and composed of AlyGa1-yAs (0.7≤y≤1, y>x); and
a semiconductor epitaxial layer that is provided above the second removal layer and composed of AltGa1-tAs (0≤t≤1), wherein
an etching rate of the second removal layer for a predetermined etching material is larger than an etching rate of the first removal layer for the predetermined etching material.

### Claim 2 (depends on 1)

The semiconductor substrate according to claim 1, wherein
the first removal layer is composed of AlxGa1-xAs (0.75<x≤0.8).

### Claim 3 (depends on 1)

The semiconductor substrate according to claim 1, wherein
the second removal layer is composed of AlyGa1-yAs (0.8<y≤1).

### Claim 4 (depends on 1)

The semiconductor substrate according to claim 1, wherein
the thickness of the first removal layer is larger than the thickness of the second removal layer.

### Claim 5 (depends on 1)

The semiconductor substrate according to claim 1, wherein
the surface of the first removal layer that is exposed at the time when the second removal layer is removed by performing etching using the predetermined etching material is rougher than the surface of the semiconductor epitaxial layer facing the second removal layer.

### Claim 6 (depends on 5)

The semiconductor substrate according to claim 5, wherein
the semiconductor epitaxial layer is composed of AltGa1-tAs (0≤t≤0.6).

### Claim 7 (depends on 1)

The semiconductor substrate according to claim 1, further comprising:
a third removal layer provided between the first removal layer and the second removal layer, wherein
an etching rate of the third removal layer for the predetermined etching material is larger than the etching rate of the first removal layer for the predetermined etching material, and smaller than the etching rate of the second removal layer for the predetermined etching material.

### Claim 8 (depends on 1)

The semiconductor substrate according to claim 1, further comprising:
a support member for supporting the semiconductor epitaxial layer such that the semiconductor epitaxial layer is positioned above the base substrate, wherein
the support member is in contact with the base substrate, the first removal layer, the second removal layer, and the semiconductor epitaxial layer, and has a shape in which the thickness of a portion of a region in contact with the second removal layer is smaller than the thickness of other regions.

### Claim 9

A method for manufacturing a semiconductor substrate comprising the steps of:
preparing a base substrate;
forming a first removal layer composed of AlxGa1-xAs (0.6<x≤0.8) on the base substrate;
forming a second removal layer, above the first removal layer, that is composed of AlyGa1-yAs (0.7<y≤1, y>x) and has a larger etching rate for a predetermined etching material than the etching rate of the first removal layer for the predetermined etching material;
forming a semiconductor epitaxial layer composed of AltGa1-tAs (0≤t≤1) above the second removal layer;
removing the second removal layer by performing etching using the predetermined etching material; and
bonding the semiconductor epitaxial layer to a destination substrate different from the base substrate after removing the second removal layer.

### Claim 10 (depends on 9)

The method for manufacturing a semiconductor substrate according to claim 9, further comprising, between the forming the semiconductor epitaxial layer and the removing the second removal layer, a step of:
providing a support member for supporting the semiconductor epitaxial layer such that the semiconductor epitaxial layer is positioned above the base substrate.

### Claim 11 (depends on 10)

The method for manufacturing a semiconductor substrate according to claim 10, further comprising, between the removing and the bonding, a step of:
cutting off the support member.

### Claim 12

A method for manufacturing a semiconductor device comprising the steps of:
preparing a semiconductor substrate including a base substrate, a first removal layer that is provided on the base substrate and composed of AlxGa1-xAs (0.6<x≤0.8), a second removal layer that is provided above the first removal layer and is composed of AlyGa1-yAs (0.7<y≤1, y>x), and a semiconductor epitaxial layer that is provided above the second removal layer and composed of AltGa1-tAs (0≤t≤1), and the semiconductor substrate having a larger etching rate of the second removal layer for a predetermined etching material than the etching rate of the first removal layer for the predetermined etching material;
removing the second removal layer by performing etching using the predetermined etching material; and
bonding the semiconductor epitaxial layer to a destination substrate different from the base substrate after removing the second removal layer.