# US 2017/0288087 A1 · Micro-size devices formed by etch of sacrificial epitaxial layers

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- Number: US 2017/0288087 A1
- Document ID: US20170288087A1
- Status: Published application
- Kind: A1
- Application number: 15/083,919
- Filed: 2016-03-29
- Published: 2017-10-05
- Earliest claimed: 2016-03-29
- Assignees: X Development LLC
- Applicants: X Development LLC
- Inventors: Martin F. Schubert; Jason D. Thompson; Michael Grundmann
- Web page: https://patentgrep.com/patent/US20170288087A1

## CPC

- H10H 20/01335: {the light-emitting regions comprising nitride materials}
- H10H 20/01: Manufacture or treatment
- H10H 20/018: {Bonding of wafers}
- H10H 20/825: containing nitrogen, e.g. GaN
- H10P 95/11: {Separation of active layers from substrates}
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Embodiments regard micro-size devices formed by etch of sacrificial epitaxial layers. An embodiment of a method includes forming a plurality of epitaxial layers on a sapphire crystal, wherein the epitaxial layers include a buffer layer on the sapphire crystal, a sacrificial layer above the buffer layer, and one or more device layers above the sacrificial layer; etching to singulate the semiconductor devices, the etching being through the one or more device layers and wholly or partially through the sacrificial layer; electrochemical etching of the sacrificial layer; and lift-off of one or more semiconductor devices from the buffer layer.

## Claims

### Claim 1

A method for fabricating semiconductor devices comprising:
forming a plurality of epitaxial layers on a sapphire crystal, wherein the epitaxial layers include:
a buffer layer on the sapphire crystal,
a sacrificial layer above the buffer layer, and
one or more device layers above the sacrificial layer;
etching to singulate the semiconductor devices, the etching being through the one or more device layers and wholly or partially through the sacrificial layer;
electrochemical etching of the sacrificial layer; and
lift-off of one or more semiconductor devices from the buffer layer.

### Claim 2 (depends on 1)

The method of claim 1, wherein the etching to singulate the one or more semiconductor layers does not etch the buffer layer.

### Claim 3 (depends on 1)

The method of claim 1, wherein the buffer layer includes GaN (gallium-nitride) material.

### Claim 4 (depends on 1)

The method of claim 1, wherein the sacrificial layer includes a highly doped semiconductor material.

### Claim 5 (depends on 1)

The method of claim 1, wherein the sacrificial layer includes one of an InGaN (Indium Gallium Nitride) or InGaN/InGaN superlattice or GaN:Si (Silicon-doped Gallium Nitride).

### Claim 6 (depends on 1)

The method of claim 1, wherein the one or more device layers are each less than 1 μm (micron) thick.

### Claim 7 (depends on 1)

The method of claim 1, wherein the electrochemical etching includes completely removing the sacrificial layer.

### Claim 8 (depends on 1)

The method of claim 1, wherein the electrochemical etching includes partially removing the sacrificial layer.

### Claim 9 (depends on 8)

The method of claim 8, wherein the lift-off of the one or more semiconductor devices includes applying a mechanical force to remove the one or more semiconductor devices from the buffer layer.

### Claim 10 (depends on 1)

The method of claim 1, further comprising applying a carrier wafer to support the one or more semiconductor devices during lift-off from the buffer layer.

### Claim 11 (depends on 1)

The method of claim 1, wherein the electrochemical etching includes wavelength selective photoelectrochemical etching.

### Claim 12 (depends on 1)

The method of claim 1, wherein the electrochemical etching includes etching at a certain voltage, the sacrificial layer being responsive to etching at the certain voltage.

### Claim 13 (depends on 1)

The method of claim 1, wherein the sacrificial layer is between 50 nm (nanometers) and 1000 nm in thickness.

### Claim 14 (depends on 1)

The method of claim 1, wherein the sacrificial layer includes a material having an intrinsic carrier concentration of greater than 5.0×1019 cm −3 at 300 Kelvin.

### Claim 15 (depends on 1)

The method of claim 1, further comprising depositing of a contact on a semiconductor device prior to the lift-off of the semiconductor device from the buffer layer.

### Claim 16 (depends on 1)

The method of claim 1, further comprising processing of the buffer and sapphire for further epitaxial growth.

### Claim 17 (depends on 1)

The method of claim 1, wherein the one or more semiconductor devices includes one or more light emitting diode (LED) devices.

### Claim at position 18

18-23. (canceled)