Method of transferring a light emitting diode

• US 8,794,501 B2
• Filed: 02/13/2012
• Issued: 08/05/2014
• 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): SAAD, ERIN BARRY
• Application Number:
  US13/372,258
• Publication Number:
  US 20130126589A1
• Time in Patent Office: 904 Days
• Field of Search: 228/122.1, 228/123.1, 228/124.1, 228/124.5, 228/178, 228/179.1, 437/904, 437/905, 437/906, 437/62, 438/404, 257/44, 257/45, 257/46, 257/653
• US Class Current: 228/179.1
• 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 method of transferring a micro LED to a receiving substrate comprising:

positioning a transfer head over a carrier substrate having an array of micro LED structures disposed thereon, each micro LED structure comprising;

a micro p-n diode; and

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

heating the bonding layer for at least one of the micro LED structures above a liquidus temperature of the bonding layer to liquefy the bonding layer;

picking up the micro p-n diode and the metallization layer for the at least one of the micro LED structures with the transfer head while the bonding layer is liquefied; and

placing the micro p-n diode and the metallization layer for the at least one of the micro LED structures on the receiving substrate.

2. The method of claim 1, wherein the micro LED structure further comprises a conformal dielectric barrier layer spanning sidewalls of the micro p-n diode;

the method further comprising;

picking up the micro p-n diode, the metallization layer and a portion of the conformal dielectric barrier layer for the at least one of the micro LED structures with the transfer head; and

placing the micro p-n diode, the metallization layer and the portion of the conformal dielectric barrier layer for the at least one of the micro LED structures on the receiving substrate.

3. The method of claim 1, wherein the liquidus temperature of the bonding layer is below 350°

C.

4. The method of claim 3, wherein the bonding layer comprises indium.

5. The method of claim 3, wherein the bonding layer comprises tin.

6. The method of claim 2, wherein the micro p-n diode comprises a top surface, a bottom surface and tapered sidewalls.

7. The method of claim 6, wherein the bottom surface is wider than the top surface.

8. The method of claim 6, wherein the conformal dielectric barrier layer spans a portion of the bottom surface of the p-n diode.

9. The method of claim 8, wherein the conformal dielectric barrier layer spans sidewalls of the metallization layer.

10. The method of claim 9, wherein the conformal dielectric barrier layer spans across a portion of the bonding layer adjacent the metallization layer.

11. The method of claim 10, further comprising cleaving the conformal dielectric barrier layer.

12. The method of claim 11, wherein cleaving the conformal dielectric barrier layer comprises transferring a pressure from the transfer head to the conformal dielectric barrier layer.

13. The method of claim 11, wherein cleaving the conformal dielectric barrier layer comprises heating the bonding layer above a liquidus temperature of the bonding layer.

14. The method of claim 13, wherein the liquidus temperature of the bonding layer is below 350°

C.

15. The method of claim 14, wherein the bonding layer comprises indium.

16. The method of claim 14, wherein the bonding layer comprises tin.

17. The method of claim 1, wherein the transfer head exerts a pick up pressure on the at least one of the micro LED structures in accordance with vacuum principles.

18. The method of claim 1, wherein the transfer head exerts a pick up pressure on the at least one of the micro LED structures in accordance with electrostatic principles.