(Al,Ga,In)N AND ZnO DIRECT WAFER BONDED STRUCTURE FOR OPTOELECTRONIC APPLICATIONS, AND ITS FABRICATION METHOD

• US 20100187555A1
• Filed: 04/01/2010
• Published: 07/29/2010
• Est. Priority Date: 06/17/2005
• Status: Active Grant

• Current Assignee: Japan Science & Technology Trading Co. Limited, Regents of the University of California (University of California)
• Original Assignee: Japan Science & Technology Trading Co. Limited, Regents of the University of California (University of California)
• Inventors: Murai, Akihiko, Thompson, Daniel B., Chen, Christina Ye, DenBaars, Steven P., Nakamura, Shuji, Mishra, Umesh K., McCarthy, Lee S.
• Granted Patent: US 8,334,151 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• 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: H01S 5/0215 Bonding to the substrate
• CPC Class Codes: H01S 5/0421 characterised by the semiconducting contacting layers electrodes H01S5/0425
• CPC Class Codes: H01S 5/18347 Mesa comprising active layer
• CPC Class Codes: H01S 5/18369 based on dielectric materials
• CPC Class Codes: H01S 5/1838 Reflector bonded by wafer fusion or by an intermediate compound
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

An (Al, Ga, In)N and ZnO direct wafer bonded light emitting diode (LED), wherein light passes through electrically conductive ZnO. Flat and clean surfaces are prepared for both the (Al, Ga, In)N and ZnO wafers. A wafer bonding process is then performed between the (Al, Ga, In)N and ZnO wafers, wherein the (Al, Ga, In)N and ZnO wafers are joined together and then wafer bonded in a nitrogen ambient under uniaxial pressure at a set temperature for a set duration. After the wafer bonding process, ZnO is shaped for increasing light extraction from inside of LED.

Claims

1. A method for producing a direct wafer bonded optical device, wherein light passes through one or more transparent ZnO conductor layers, comprising:

(a) preparing flat and clean surfaces for one or more transparent ZnO conductor layers and a III-nitride optoelectronic device to be bonded; and

(b) performing a direct wafer bonding process between the III-nitride optoelectronic device and a Zn face of the transparent ZnO conductor layers to form at least one wafer bonding interface that is a fusion of the transparent conductor layers and the III-nitride optical device, wherein an O face of the transparent ZnO conductor layers is shaped to improve light extraction from the transparent ZnO conductor layers.

2. The method of claim 1, wherein the III-nitride optoelectronic device and the transparent conductor layers are joined together and then wafer bonded in a nitrogen ambient under uniaxial pressure at a set temperature for a set duration.

3. The method of claim 1, wherein the transparent conductor layers surfaces to be bonded comprise the Zn-face of c-plane ZnO

4. The method of claim 1, wherein the transparent conductor layers surfaces to be bonded comprise the O-face of c-plane ZnO

5. The method of claim 1, wherein the III-nitride optoelectronic device and the transparent conductor layers are loaded into a wafer-bonding furnace, and the furnace is heated to a temperature of 600°

C. for 1 hour in an N₂ gas flow.

6. The method of claim 1, further comprising enhancing electrical conductivity of the wafer bonding interface prior to direct wafer bonding.

7. The method of claim 6, wherein the transparent conductor layers surface is plasma treated prior to the wafer bonding process to enhance electrical conductivity at the wafer bonding interface.

8. The method of claim 1, wherein the III-nitride optoelectronic device surface is partially shaped prior to the wafer bonding process to strengthen the wafer bonding interface.

9. The method of claim 1, wherein a surface of the transparent conductor layers is roughened or shaped after or before the wafer bonding process.

10. The method of claim 9, wherein the surface is an O-face of the ZnO.

11. The method of claim 9, wherein the shaping is by anisotropic etching.

12. The method of claim 11, wherein the anisotropic etching comprises a chemical etching.

13. The method of claim 12, wherein the etching is in Hydrochloric Acid (HCL) or diluted HCL.

14. An optical device fabricated by the method of claim 1.