# US 10,763,174 B2 · Method for recovering carbon-face-polarized silicon carbide substrate

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- Number: US 10,763,174 B2
- Document ID: US10763174B2
- Status: Granted
- Kind: B2
- Application number: 16/562,452
- Filed: 2019-09-06
- Published: 2019-12-26
- Granted: 2020-09-01
- Earliest claimed: 2018-09-21
- Assignees: Suzhou Han Hua Semiconductor Co., Ltd.
- Applicants: Suzhou Han Hua Semiconductor Co., Ltd
- Inventors: Xianfeng Ni; Qian Fan; Wei He
- Web page: https://patentgrep.com/patent/US10763174B2

## CPC

- H10P 50/648: {Anisotropic liquid etching}
- H10P 95/112: {leaving a reusable substrate, e.g. epitaxial lift off}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10P 50/646: {of Group III-V materials}
- H10P 70/40: {Cleaning for reclaiming}
- H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method for recovering carbon-face-polarized silicon carbide substrates, including: providing an epitaxial structure, the epitaxial structure includes a carbon-face-polarized silicon carbide substrate to be recovered, as well as a nitrogen-face-polarized gallium nitride buffer layer, a barrier layer and a nitrogen-face-polarized gallium nitride channel layer that are sequentially deposited on the silicon carbide substrate; removing the nitrogen-face-polarized gallium nitride buffer layer, the barrier layer and the nitrogen-face-polarized gallium nitride channel layer by wet etching; and cleaning and blowing dry the carbon-face-polarized silicon carbide substrate.

## Claims

### Claim 1

A method of recovering carbon-face-polarized silicon carbide substrates, comprising:
providing an epitaxial structure, wherein the epitaxial structure comprises a carbon-face-polarized silicon carbide substrate to be recovered, a nitrogen-face-polarized gallium nitride buffer layer, a barrier layer and a nitrogen-face-polarized gallium nitride channel layer sequentially laminated on the carbon-face-polarized silicon carbide substrate;
removing the nitrogen-face-polarized gallium nitride buffer layer, the barrier layer and the nitrogen-face-polarized gallium nitride channel layer by wet etching; and
cleaning and blowing dry the carbon-face-polarized silicon carbide substrate.

### Claim 2 (depends on 1)

The method of recovering the carbon-face-polarized silicon carbide substrates according to claim 1, wherein, the wet etching solution comprises at least one selected from the group consisting of sodium hydroxide, phosphoric acid, and citric acid.

### Claim 3 (depends on 1)

The method of recovering the carbon-face-polarized silicon carbide substrates according to claim 1, wherein, a rate of the wet etching is greater than 100 nm/min.

### Claim 4 (depends on 1)

The method for recovering the carbon-face-polarized silicon carbide substrates according to claim 1, wherein, the step of cleaning and blowing dry the surface of the carbon-face-polarized silicon carbide substrate comprises:
cleaning the surface of the carbon-face-polarized silicon carbide substrate with deionized water; and
blowing dry the carbon-face-polarized silicon carbide substrate with nitrogen gas.

### Claim 5 (depends on 1)

The method of recovering the carbon-face-polarized silicon carbide substrates according to claim 1, wherein, the wet etching uses a 10%-50% (by weight) KOH solution.

### Claim 6 (depends on 5)

The method of recovering the carbon-face-polarized silicon carbide substrates according to claim 5, further comprising: adding ethylene glycol to the KOH solution and heating the KOH solution to above 100° C.

### Claim 7 (depends on 1)

The method of recovering the carbon-face-polarized silicon carbide substrates according to claim 1, wherein, the epitaxial structure is irradiated with a UV light during the wet etching.

### Claim 8 (depends on 7)

The method of recovering the carbon-face-polarized silicon carbide substrates according to claim 7, wherein, the UV light has a wavelength shorter than a wavelength corresponding to a gallium nitride bandgap of the nitrogen-face-polarized gallium nitride buffer layer.