LIGHT EMITTING DIODE ELEMENT AND METHOD FOR FABRICATING THE SAME

• US 20090159870A1
• Filed: 12/20/2007
• Published: 06/25/2009
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: Tekcore Co Limited (Tekcore)
• Original Assignee: Tekcore Co Limited (Tekcore)
• Inventors: Lee, Chia-Ming, Chyi, Jen-Inn, Lin, Hung-Cheng
• Granted Patent: US 8,101,447 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate

Abstract

The present invention discloses a light emitting diode (LED) element and a method for fabricating the same, which can promote light extraction efficiency of LED, wherein a substrate is etched to obtain basins with inclined natural crystal planes, and an LED epitaxial structure is selectively formed inside the basin. Thereby, an LED element having several inclines is obtained. Via the inclines, the probability of total internal reflection is reduced, and the light extraction efficiency of LED is promoted.

Claims

1. A method for fabricating a light emitting diode element comprising steps:

(a) providing a substrate, forming a passivation layer on said substrate and defining a plurality of polygonal etch areas;

(b) etching said substrate to form on said etch areas a plurality of basins with inclined natural crystal planes and a bottom plane;

(c) forming a light emitting diode structure on said bottom plane of said basin via epitaxially growing on said bottom plane an n-type III-V group compound layer, an active layer and a p-type III-V group compound layer, wherein said active layer is interposed between said n-type III-V group compound layer and said p-type III-V group compound layer and functions as a light emitting zone, and wherein for providing a forward bias, said p-type III-V group compound layer is electrically coupled to a p-type ohmic contact electrode, and said n-type III-V group compound layer is electrically coupled to an n-type ohmic contact electrode; and

(d) grinding said substrate, cutting and splitting said substrate having been ground into light emitting diode chips.

2. The method for fabricating the light emitting diode element according to claim 1, wherein said substrate is made of sapphire, silicon carbide (SiC), silicon (Si), gallium arsenide (GaAs) or aluminum nitride (AlN).

3. The method for fabricating the light emitting diode element according to claim 1, wherein said passivation layer has a width of between 5 and 50 microns, and said etch area has an inner diameter of between 200 and 2000 microns.

4. The method for fabricating the light emitting diode element according to claim 1, wherein said etch area has a shape of a rectangle, circle, triangle, star, or polygon.

5. The method for fabricating the light emitting diode element according to claim 1, wherein said basin has a depth of between 0.5 and 50 microns.

6. The method for fabricating the light emitting diode element according to claim 1, wherein in said Step (b), etching time is prolonged until said passivation layer is all removed.

7. The method for fabricating the light emitting diode element according to claim 1, wherein said Step (b) further comprises Step (b-1):

pattern-etching said bottom plane of said basin to obtain a rugged surface for increasing light extraction efficiency.

8. A method for fabricating the light emitting diode element comprising steps:

(a) providing a substrate, forming a passivation layer on said substrate and defining a plurality of polygonal etch areas;

(b) etching said substrate to form on said etch areas a plurality of basins with inclined natural crystal planes and a bottom plane, and pattern-etching said bottom plane of said basin to obtain a rugged surface;

(c) forming a light emitting diode structure on said bottom plane of said basin via epitaxially growing on said bottom plane an n-type III-V group compound layer, an active layer and a p-type III-V group compound layer in sequence, wherein said active layer is interposed between said n-type III-V group compound layer and said p-type III-V group compound layer and functions as a light emitting zone;

(d) vapor-depositing a p-type ohmic contact metal layer on said p-type III-V group compound layer, and connecting said p-type ohmic contact metal layer with a heat-conduction substrate;

(e) removing said substrate;

(f) vapor-depositing an n-type ohmic contact metal layer on said n-type III-V group compound layer; and

(g) cutting and splitting the total structure into light emitting diode chips.

9. The method for fabricating the light emitting diode element according to claim 8, wherein said substrate is made of sapphire, silicon carbide (SiC), silicon (Si), gallium arsenide (GaAs) or aluminum nitride (AlN).

10. The method for fabricating the light emitting diode element according to claim 8, wherein said passivation layer has a width of between 5 and 50 microns, and said etch area has an inner diameter of between 200 and 2000 microns.

11. The method for fabricating the light emitting diode element according to claim 8, wherein said etch area has a shape of a rectangle, circle, triangle, star, or polygon.

12. The method for fabricating the light emitting diode element according to claim 8, wherein said basin has a depth of between 0.5 and 50 microns.

13. The method for fabricating the light emitting diode element according to claim 8, wherein the material of said heat-conduction substrate is selected from the group consisting of gold (Au), aluminum (Al), copper (Cu), silicon (Si), gallium phosphide (GaP), silicon carbide (SiC), etc.;

alternatively, the material of said heat-conduction substrate is one combination of the above mentioned materials.

14. The method for fabricating the light emitting diode element according to claim 8, wherein said substrate is removed with a wet-etching method, a dry-etching method, a laser lift off method, or a method of using different thermal expansion coefficients, wherein said substrate is spontaneously separated from said light emitting diode structure during temperature variation.

15. A light emitting diode element comprising:

a substrate, wherein the surface of said substrate is etched to form basins having inclined natural crystal planes and a bottom plane; and

a light emitting diode structure formed via epitaxially growing on said bottom plane of said basin an n-type III-V group compound layer, an active layer and a p-type III-V group compound layer in sequence, wherein said active layer is interposed between said n-type III-V group compound layer and said p-type III-V group compound layer and functions as a light emitting zone, and wherein for providing a forward bias, said p-type III-V group compound layer is electrically coupled to a p-type ohmic contact electrode, and said n-type III-V group compound layer is electrically coupled to an n-type ohmic contact electrode.

16. The light emitting diode element according to claim 15, wherein said substrate is made of sapphire, silicon carbide (SiC), silicon (Si), gallium arsenide (GaAs) or aluminum nitride (AlN).

17. The light emitting diode element according to claim 15, wherein a passivation layer is formed on the surface of said substrate and along the perimeter of said basin.

18. The light emitting diode element according to claim 15, wherein said basin has a shape of a rectangle, circle, triangle, star, or polygon.

19. The light emitting diode element according to claim 15, wherein said basin has a depth of between 0.5 and 50 microns and has an inner diameter of between 200 and 2000 microns.

20. The light emitting diode element according to claim 15, wherein said bottom plane of said basin is a rugged surface.

21. The light emitting diode element according to claim 15, wherein said active layer is a dual heterogeneous (DH) junction structure, a single quantum well (SQW) structure or a multiple quantum well (MQW) structure.

22. The light emitting diode element according to claim 15, wherein said light emitting diode structure is electrically coupled to a heat dissipation/reflection substrate via said p-type ohmic contact electrode and sad n-type ohmic contact electrode.

23. The light emitting diode element according to claim 22, wherein said heat dissipation/reflection substrate includes a reflective metal layer and a heat-conduction substrate;

one surface of said reflective metal layer is electrically coupled to said light emitting diode structure, and the other surface of said reflective metal layer is connected to said heat-conduction substrate.

24. The light emitting diode element according to claim 23, wherein the material of said reflective metal layer is selected from the group consisting of gold (Au), aluminum (Al), copper (Cu), etc.;

alternatively, the material of said reflective metal layer is one combination of the above mentioned materials.

25. The light emitting diode element according to claim 23, wherein the material of said heat-conduction substrate is selected from the group consisting of gold (Au), aluminum (Al), copper (Cu), silicon (Si), gallium phosphide (GaP), silicon carbide (SiC), etc.;

alternatively, the material of the heat-conduction substrate is one combination of the above mentioned materials.

26. A light emitting diode element comprising:

a light emitting diode structure with inclines formed via etching a substrate to obtain basins having inclined natural crystal planes and a bottom plane, and epitaxially growing on said bottom plane an n-type III-V group compound layer, an active layer and a p-type III-V group compound layer in sequence, wherein said active layer is interposed between said n-type III-V group compound layer and said p-type III-V group compound layer and functions as a light emitting zone;

a p-type ohmic contact metal layer formed on said p-type III-V group compound layer;

a heat-conduction substrate connected with said p-type ohmic contact metal layer; and

an n-type ohmic contact metal layer formed on said n-type III-V group compound layer.

27. The light emitting diode element according to claim 26, wherein said light emitting diode structure has a shape of a rectangle, circle, triangle, star, or polygon.

28. The light emitting diode clement according to claim 26, wherein said light emitting diode structure has a thickness of between 0.5 and 50 microns and has a diameter of between 200 and 2000 microns.

29. The light emitting diode element according to claim 26, wherein said n-type III-V group compound layer has a rugged surface.

30. The light emitting diode element according to claim 26, wherein said active layer is a dual heterogeneous (DH) junction structure, a single quantum well (SQW) structure or a multiple quantum well (MQW) structure.