# US 8,541,314 B2 · Method for smoothing group III nitride semiconductor substrate

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- Number: US 8,541,314 B2
- Document ID: US8541314B2
- Status: Granted
- Kind: B2
- Application number: 13/067,228
- Filed: 2011-05-18
- Published: 2012-07-19
- Granted: 2013-09-24
- Earliest claimed: 2011-01-14
- Assignees: National Chiao Tung University
- Applicants: Wei-I Lee; Kuei-Ming Chen; Yin-Hao Wu; Yen-Hsien Yeh
- Inventors: Wei-I Lee; Kuei-Ming Chen; Yin-Hao Wu; Yen-Hsien Yeh
- Web page: https://patentgrep.com/patent/US8541314B2

## CPC

- H10P 90/00: Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement
- H10P 90/126: {by chemical etching}
- H10P 90/1904: {Preparing vertically inhomogeneous wafers}
- H10P 50/246: {of Group III-V materials}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

The invention discloses a smoothing method to decrease bowing of group III nitride semiconductor substrate. The certain face of group III nitride semiconductor substrates is etched under the appropriate etching recipe and time, the certain morphology such as rod-type and other structures are appeared at the certain face. And such structures releases the compressive stresses at these certain faces, resulting in clearly increasing the bowing radius of the group III nitride semiconductor substrates, finally decreasing the bowing phenomenon of the group III nitride semiconductor substrate.

## Claims

### Claim 1

A method smoothing a group III nitride semiconductor substrate, comprising:
providing a convex free-standing gallium nitride substrate;
forming a dielectric layer on a top of said convex free-standing gallium nitride substrate;
using a wet etching method to etch a bottom of said convex free-standing gallium nitride substrate: and
removing said dielectric layer.

### Claim 2 (depends on 1)

The method for smoothing said group III nitride semiconductor substrate according to claim 1, wherein said dielectric layer further comprises a metal layer.

### Claim 3 (depends on 1)

The method for smoothing said group III nitride semiconductor substrate according to claim 1, wherein said wet etching method further comprises an electrochemical etching method.

### Claim 4

A method for smoothing a of group III nitride semiconductor substrate, comprising:
providing a concave free-standing gallium nitride substrate;
forming a dielectric layer under said concave free-standing gallium nitride substrate;
using a wet etching method to etch a top of said concave free-standing gallium nitride substrate; and
removing said dielectric layer.

### Claim 5 (depends on 4)

The method for smoothing said group III nitride semiconductor substrate according to claim 4, wherein the dielectric layer comprises a metal layer.

### Claim 6 (depends on 4)

The method for smoothing said group III nitride semiconductor substrate according to claim 4, wherein the wet etching method comprises an electrochemical etching method.