# US 9,520,533 B2 · Ultraviolet light emitting device separated from growth substrate and method of fabricating the same

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- Number: US 9,520,533 B2
- Document ID: US9520533B2
- Status: Granted
- Kind: B2
- Application number: 14/875,578
- Filed: 2015-10-05
- Published: 2016-02-04
- Granted: 2016-12-13
- Earliest claimed: 2013-04-05
- Assignees: Seoul Viosys Co., Ltd.
- Applicants: Seoul Viosys Co., Ltd.
- Inventors: Chang Suk Han; Hwa Mok Kim; Mi So Ko; A Ram Cha Lee; Dae Woong Suh
- Web page: https://patentgrep.com/patent/US9520533B2

## CPC

- H10H 20/812: within the light-emitting regions, e.g. having quantum confinement structures
- H10H 20/0137: {the light-emitting regions comprising nitride materials}
- H10H 20/018: {Bonding of wafers}
- H10H 20/811: having quantum effect structures or superlattices, e.g. tunnel junctions
- H10H 20/815: having stress relaxation structures, e.g. buffer layers
- H10H 20/82: Roughened surfaces, e.g. at the interface between epitaxial layers
- H10H 20/821: of the light-emitting regions, e.g. non-planar junctions
- H10H 20/824: comprising only Group III-V materials, e.g. GaP
- H10H 20/825: containing nitrogen, e.g. GaN
- H10P 14/271: {characterised by the preparation of substrate for selective deposition}
- H10P 14/276: {Lateral overgrowth}
- H10P 14/3216: {Nitrides}
- H10P 14/3252: {Alternating layers, e.g. superlattice}
- H10P 14/3416: {Nitrides}
- H10H 20/819: characterised by their shape, e.g. curved or truncated 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

A UV light emitting device and a method for fabricating the same are disclosed. The method includes forming a first super-lattice layer including AlxGa(1-x)N on a substrate, forming a sacrificial layer including AlzGa(1-z)N on the first super-lattice layer, partially removing the sacrificial layer, forming an epitaxial layer on the sacrificial layer, and separating the substrate from the epitaxial layer, wherein the sacrificial layer includes voids, the substrate is separated from the epitaxial layer at the sacrificial layer, and forming an epitaxial layer includes forming an n-type semiconductor layer including n-type AluGa(1-u)N (0<u≦z≦x<1). With this structure, the light emitting device can emit UV light and be separated from the substrate.

## Claims

### Claim 1

A method of fabricating a UV light emitting device, comprising:
forming a first super-lattice layer comprising AlxGa(1-x)N on a substrate;
forming a sacrificial layer comprising AlzGa(1-z)N on the first super-lattice layer;
partially removing the sacrificial layer;
forming an epitaxial layer on the sacrificial layer; and
separating the substrate from the epitaxial layer,
wherein the sacrificial layer comprises voids, the substrate is separated from the epitaxial layer at the sacrificial layer, and
wherein the forming of the epitaxial layer comprises forming an n-type semiconductor layer comprising n-type AluGa(1-u)N (0<u≦z≦x<1).

### Claim 2 (depends on 1)

The method of claim 1, wherein the forming of the n-type semiconductor layer comprises:
forming a first n-type semiconductor layer on the sacrificial layer at a first temperature;
forming a second n-type semiconductor layer on the first n-type semiconductor layer at a second temperature; and
forming a third n-type semiconductor layer on the second n-type semiconductor layer at a third temperature,
wherein the second temperature is different from the first temperature and the third temperature.

### Claim 3 (depends on 2)

The method of claim 2, wherein the first temperature is less than or equal to the third temperature, and the third temperature is less than the second temperature.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
forming a second super-lattice layer comprising AlyGa(1-y)N (0<u≦z≦y≦x<1) on the first super-lattice layer, before forming the sacrificial layer,
wherein the x ranges from 0.75 to 0.85, the z ranges from 0.55 to 0.65, and the u ranges from 0.45 to 0.55.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first super-lattice layer comprises a stack structure including AlN layers and AlxGa(1-x)N layers alternately stacked one above another.

### Claim 6 (depends on 1)

The method of claim 1, further comprising:
forming a buffer layer on the substrate, before forming the first super-lattice layer.

### Claim 7 (depends on 6)

The method of claim 6, wherein the buffer layer comprises AlN.

### Claim 8 (depends on 1)

The method of claim 1, wherein the sacrificial layer comprises an n-type impurity, and
wherein the partially removing of the sacrificial layer comprises:
forming a mask pattern on the sacrificial layer; and
forming fine voids in the sacrificial layer through electrochemical etching of the sacrificial layer.

### Claim 9 (depends on 8)

The method of claim 8, wherein at least some of the fine voids are combined to form the voids in the sacrificial layer during the formation of the epitaxial layer.

### Claim 10 (depends on 8)

The method of claim 8, wherein the separating of the substrate from the epitaxial layer comprises chemically etching the mask pattern using an etching solution.

### Claim 11 (depends on 8)

The method of claim 8, wherein the separating of the substrate from the epitaxial layer comprises applying stress to the sacrificial layer.

### Claim 12 (depends on 1)

The method of claim 1, wherein the separating of the substrate from the epitaxial layer comprises applying stress to the sacrificial layer.

### Claim 13 (depends on 1)

The method of claim 1, further comprising:
forming a secondary substrate on the epitaxial layer, before separating the substrate from the epitaxial layer.

### Claim 14 (depends on 13)

The method of claim 13, further comprising:
dividing the epitaxial layer and the secondary substrate, from which the substrate is separated, into a plurality of areas.

### Claim 15

A template for fabrication of a UV light emitting device, comprising:
a substrate;
a first super-lattice layer disposed on the substrate and comprising AlxGa(1-x)N; and
a sacrificial layer disposed on the first super-lattice layer and comprising AlzGa(1-z)N (0<z≦x<1);
wherein the sacrificial layer comprises an n-type impurity having a concentration of 3×1018/cm3 to 3×1019/cm3.

### Claim 16 (depends on 15)

The template of claim 15, further comprising:
a second super-lattice layer disposed between the first super-lattice layer and the sacrificial layer and comprising AlyGa(1-y)N (0≦z≦y≦x<1).

### Claim 17 (depends on 15)

The template of claim 15, further comprising:
an AlN buffer layer disposed between the substrate and the first super-lattice layer.