Micro light emitting diode

• US 8,809,875 B2
• Filed: 02/13/2012
• Issued: 08/19/2014
• Est. Priority Date: 11/18/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: LuxVue Techonology Corporation (Apple Inc.)
• Inventors: Bibl, Andreas, Higginson, John A., Law, Hung-Fai Stephen, Hu, Hsin-Hua
• Primary Examiner(s): Maldonado, Julio J
• Assistant Examiner(s): Singh, Harpreet
• Application Number:
  US13/372,222
• Publication Number:
  US 20130126891A1
• Time in Patent Office: 918 Days
• Field of Search: None
• US Class Current: 257/79
• CPC Class Codes: F21V 7/00 Reflectors for light sources characterised by cooling arrangements F21V29/505
• CPC Class Codes: H01L 2224/95 at chip-level, i.e. with connecting carried out on a plurality of singulated devices, i.e. on diced chips
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 29/0684 characterised by the shape, relative sizes or dispositions of the semiconductor regions or junctions between the regions
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/28 containing only elements of Group II and Group VI of the Periodic Table
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table

Abstract

A micro light emitting diode (LED) and a method of forming an array of micro LEDs for transfer to a receiving substrate are described. The micro LED structure may include a micro p-n diode and a metallization layer, with the metallization layer between the micro p-n diode and a bonding layer. A conformal dielectric barrier layer may span sidewalls of the micro p-n diode. The micro LED structure and micro LED array may be picked up and transferred to a receiving substrate.

Claims

1. A micro LED structure comprising:

a micro p-n diode;

a metallization layer;

wherein the metallization layer is between the micro p-n diode and a bonding layer formed on a substrate; and

a conformal barrier layer comprising a single layer of a same material that spans sidewalls of the micro p-n diode, sidewalls of the metallization layer, and sidewalls of the bonding layer.

2. The micro LED structure of claim 1, wherein the bonding layer has a liquidus temperature below approximately 350°

C.

3. The micro LED structure of claim 1, wherein the conformal barrier layer forms an outline of the topography of the sidewalls of the micro p-n diode, the sidewalls of the metallization layer, and the sidewalls of the bonding layer.

4. The micro LED structure of claim 1, wherein the single layer of the same material is a conformal dielectric barrier layer that partially spans a bottom surface of the micro p-n diode.

5. The micro LED structure of claim 4, further comprising an opening in the conformal dielectric barrier layer exposing a top surface of the micro p-n diode, wherein the opening has a width selected from the group consisting of:

greater than a width of the top surface of the micro p-n diode;

less than the width of the top surface of the micro p-n diode; and

approximately the same as the width of the top surface of the micro p-n diode.

6. The micro LED structure of claim 1, wherein:

the micro p-n diode comprises a top surface and a bottom surface;

the metallization layer comprises a top surface and a bottom surface; and

the bottom surface of the micro p-n diode is wider than the top surface of the metallization layer.

7. The micro LED structure of claim 1, wherein the bonding layer comprises indium or tin.

8. The micro LED structure of claim 1, wherein the bonding layer comprises polyethylene or polypropylene.

9. The micro LED structure of claim 1, wherein the micro p-n diode comprises gallium nitride.

10. The micro LED structure of claim 1, wherein the metallization layer comprises an electrode layer and a barrier layer between the electrode layer and the bonding layer.

11. The micro LED structure of claim 1, wherein the micro p-n diode comprises a top surface, a bottom surface and tapered sidewalls.

12. The micro LED of claim 11, wherein the bottom surface is wider than the top surface.

13. The micro LED of claim 11, wherein the top surface is wider than the bottom surface or has a same width as the bottom surface.

14. The micro LED structure of claim 1, wherein:

the micro p-n diode comprises a top surface and a bottom surface;

the bonding layer comprises a top surface and a bottom surface; and

the bottom surface of the micro p-n diode is wider than the top surface of the bonding layer.

15. The micro LED structure of claim 1, wherein:

the micro p-n diode comprises a top surface and a bottom surface;

the bonding layer comprises a top surface and a bottom surface; and

the bottom surface of the micro p-n diode is approximately the same width as the top surface of the bonding layer.

16. The micro LED structure of claim 1, wherein the single layer of the same material that spans the sidewalls of the micro p-n diode, the sidewalls of the metallization layer, and the sidewalls of the bonding layer is continuous.

17. The micro LED structure of claim 1, wherein the same material comprises Al₂O₃.

18. A micro LED array comprising:

a plurality of locations of a bonding layer on a substrate;

a corresponding plurality of micro LED structures on the plurality of locations of the bonding layer, wherein each micro LED structure comprises;

a micro p-n diode; and

a metallization layer, wherein the metallization layer is between the micro p-n diode and a respective location of the bonding layer; and

a conformal barrier layer comprising a single layer of a same material that spans sidewalls of each micro p-n diode, sidewalls of each metallization layer, and sidewalls of each of the plurality of locations of the bonding layer.

19. The micro LED array of claim 18, wherein the bonding layer has a liquidus temperature below approximately 350°

C.

20. The micro LED array of claim 18, wherein the conformal barrier layer forms an outline of the topography of the sidewalls of the micro p-n diode, the sidewalls of the metallization layer, and the sidewalls of the bonding layer.

21. The micro LED array of claim 18, wherein the single layer of the same material is a conformal dielectric barrier layer that partially spans a bottom surface of each micro p-n diode.

22. The micro LED structure of claim 21, further comprising a plurality of openings in the conformal dielectric barrier layer exposing a top surface of each micro p-n diode, wherein each opening has a width selected from the group consisting of:

greater than a width of the top surface of a corresponding micro p-n diode;

less than the width of the top surface of the corresponding micro p-n diode; and

approximately the same as the width of the top surface of corresponding micro p-n diode.

23. The micro LED structure of claim 18, wherein the plurality of locations of the bonding layer are laterally separate.

24. The micro LED array of claim 23, wherein the substrate comprises a respective plurality of pillars, and the plurality of locations of the bonding layer are formed on the respective plurality of pillars.

25. The micro LED array of claim 24, wherein each micro p-n diode comprises a bottom surface which is approximately the same width as a top surface a respective pillar.

26. The micro LED array of claim 24, wherein each micro p-n diode comprises a bottom surface which is wider than width of a top surface a respective pillar.

27. The micro LED array of claim 24, wherein the respective plurality of pillars each have a respective height which is greater than a respective thickness of each of the locations of the bonding layer.

28. The micro LED array of claim 27, wherein each respective height is at least twice the respective thickness.

29. The micro LED array of claim 18, wherein the plurality of locations of the bonding layer are not laterally separate.

30. The micro LED array of claim 18, wherein:

each micro p-n diode comprises a top surface and a bottom surface;

each metallization layer comprises a top surface and a bottom surface; and

the bottom surface of each micro p-n diode is wider than the corresponding top surface of the metallization layer.

31. The micro LED array of claim 18, wherein each micro p-n diode comprises a top surface and a bottom surface which is wider than the top surface.

32. The micro LED structure of claim 18, wherein each portion of the single layer of the same material that spans the sidewalls of the each micro p-n diode, the sidewalls of the each metallization layer, and the sidewalls of the each bonding layer is continuous.

33. The micro LED structure of claim 18, wherein the same material comprises Al₂O₃.