Methods of fabricating light emitting diodes by masking and wet chemical etching

• US 9,281,445 B2
• Filed: 10/21/2014
• Issued: 03/08/2016
• Est. Priority Date: 04/23/2013
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Donofrio, Matthew
• Primary Examiner(s): YUSHIN, NIKOLAY K
• Application Number:
  US14/519,746
• Publication Number:
  US 20150037918A1
• Time in Patent Office: 504 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

An LED includes a mesa having a Group III Nitride mesa face and a mesa sidewall, on an underlying LED structure. The mesa face includes Group III Nitride surface features having tops that are defined by mask features, having bottoms, and having sides that extend along crystal planes of the Group III Nitride. The mask features may include a two-dimensional array of dots that are spaced apart from one another. Related fabrication methods are also disclosed.

Claims

1. A method of fabricating a Light Emitting Diode (LED) having a Group III Nitride layer including a Group III Nitride face, the method comprising:

masking the Group III Nitride face with a two-dimensional array of dots of a mask material that are spaced apart from one another; and

wet chemical etching the Group III Nitride face that is exposed by the two-dimensional array of dots of the mask material that are spaced apart from one another to produce Group III Nitride features having sides that extend along crystal planes of the Group III Nitride layer, wherein sides of two adjacent Group III Nitride features touch one another.

2. A method according to claim 1 wherein the dots of the mask material comprise elliptical, circular and/or polygonal dots of the mask material.

3. A method according to claim 1 wherein the mask material comprises a transparent mask material.

4. A method according to claim 3 wherein the transparent mask material comprises silicon nitride.

5. A method according to claim 1 wherein the following is performed between the masking and the wet chemical etching:

dry etching the Group III Nitride face that is exposed by the two-dimensional array of dots of the mask material that are spaced apart from one another.

6. A method according to claim 1 wherein the wet chemical etching is followed by:

at least partially removing the two-dimensional array of dots of the mask material.

7. A method according to claim 6 wherein the at least partially removing the two-dimensional array of dots of the mask material comprises shaping the two-dimensional array of dots of the mask material.

8. A method according to claim 6 wherein the at least partially removing the two-dimensional array of dots of the mask material comprises completely removing the two-dimensional array of dots of the mask material and wherein the completely removing is followed by:

texturing the Group III Nitride face from which the two-dimensional array of dots of the mask material has been removed.

9. A method according to claim 1 wherein the mask material comprises an opaque mask material.

10. A method according to claim 1 wherein the mask material comprises a reflective mask material.

11. A method according to claim 1:

wherein the Group III Nitride features comprise tops defined by the two-dimensional array of dots, and bottoms, such that the sides extend between the tops and the bottoms along the crystal planes of the Group III Nitride layer, and

wherein a height of the Group III nitride features is less than about 50% of a thickness of the Group III Nitride layer.

12. A method according to claim 1:

wherein the Group III Nitride features comprise tops defined by the two-dimensional array of dots, and bottoms, such that the sides extend between the tops and the bottoms along the crystal planes of the Group III Nitride layer, and

wherein an aspect ratio of a height of the Group III Nitride features to a width of the bottoms of the Group III Nitride features is at least about 0.2.

13. A method according to claim 1:

wherein the Group III Nitride features comprise tops defined by the two-dimensional array of dots, and bottoms, such that the sides extend between the tops and the bottoms along the crystal planes of the Group III Nitride layer, and

wherein the bottoms of the Group III Nitride features comprise about 100% of an area of the Group III Nitride face.

14. A method of fabricating a Light Emitting Diode (LED) having a Group III Nitride layer including a Group III Nitride face, the method comprising:

masking the Group III Nitride face with a two-dimensional array of dots of a mask material that are spaced apart from one another; and

wet chemical etching the Group III Nitride face that is exposed by the two-dimensional array of dots of the mask material that are spaced apart from one another to produce Group III Nitride features having sides that extend along crystal planes of the Group III Nitride layer, and a plurality of non-truncated cones between at least two adjacent sides of the Group III Nitride features.

15. A method according to claim 14 wherein the dots of the mask material comprise elliptical, circular and/or polygonal dots of the mask material.

16. A method according to claim 14 wherein the following is performed between the masking and the wet chemical etching:

dry etching the Group III Nitride face that is exposed by the two-dimensional array of dots of the mask material that are spaced apart from one another.

17. A method according to claim 14 wherein the wet chemical etching is followed by:

at least partially removing the two-dimensional array of dots of the mask material.

18. A method according to claim 17 wherein the at least partially removing the two-dimensional array of dots of the mask material comprises shaping the two-dimensional array of dots of the mask material.

19. A method according to claim 17 wherein the at least partially removing the two-dimensional array of dots of the mask material comprises completely removing the two-dimensional array of dots of the mask material and wherein the completely removing is followed by:

texturing the Group III Nitride face from which the two-dimensional array of dots of the mask material has been removed.

20. A method according to claim 14 wherein the non-truncated cones between the at least two adjacent sides of the Group III Nitride features are shorter than the Group III Nitride features.