Ultraviolet light emitting device separated from growth substrate and method of fabricating the same

Patent metadata

Field	Value
Publication number	US-9520533-B2
Application number	US-201514875578-A
Country	US
Kind code	B2
Filing date	Oct 5, 2015
Priority date	Apr 5, 2013
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

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 Al x Ga (1-x) N on a substrate, forming a sacrificial layer including Al z Ga (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 Al u Ga (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.

First claim

The invention claimed is:

1. A method of fabricating a UV light emitting device, comprising:
forming a first super-lattice layer comprising Al x Ga (1-x) N on a substrate;
forming a sacrificial layer comprising Al z Ga (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 Al u Ga (1-u) N (0<u≦z≦x<1).

2. 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.

3. 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.

4. The method of claim 1 , further comprising:
forming a second super-lattice layer comprising Al y Ga (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.

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

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

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

8. 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.

9. 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.

10. 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.

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

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

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

14. 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.

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 Al x Ga (1-x) N; and
a sacrificial layer disposed on the first super-lattice layer and comprising Al z Ga (1-z) N (0<z≦x<1);
wherein the sacrificial layer comprises an n-type impurity having a concentration of 3×10 18 /cm 3 to 3×10 19 /cm 3 .

16. 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 Al y Ga (1-y) N (0≦z≦y≦x<1).

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

Assignees

• Seoul Viosys Co Ltd

Inventors

• Han Chang Suk
• Kim Hwa Mok
• Ko Mi So
• Lee A Ram Cha
• Suh Dae Woong

Classifications

• H10P14/3416

  Nitrides · CPC title

• H10P14/3252

  Alternating layers, e.g. superlattice · CPC title

• H10P14/3216 Primary

  Nitrides · CPC title

• H10P14/276

  Lateral overgrowth · CPC title

• H10P14/271

  characterised by the preparation of substrate for selective deposition · CPC title