Group III nitride semiconductor light-emitting device and production method therefor

• US 20100078672A1
• Filed: 09/30/2009
• Published: 04/01/2010
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Moriyama, Miki, Goshonoo, Koichi
• Granted Patent: US 8,309,381 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• 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

Abstract

Provided is a method for producing a Group III nitride semiconductor light-emitting device including a GaN substrate serving as a growth substrate, which method realizes processing of the GaN substrate to have a membrane structure at high reproducibility. In the production method, a stopper layer of AlGaN having an Al compositional proportion of 20% is formed on the top surface of a GaN substrate; an n-type layer, an active layer, a p-type layer, and a p-electrode are sequentially formed on the stopper layer; and the p-electrode is joined to a support substrate. Subsequently, a mask having a center-opening pattern is formed on the bottom surface of the GaN substrate, and the bottom surface is subjected to PEC etching. The bottom surface is irradiated with light having a wavelength corresponding to an energy higher than the band gap of GaN, but lower than the band gap of AlGaN having an Al compositional proportion of 20%. Since etching stops when it proceeds to a depth reaching the stopper layer, a membrane structure can be formed at high reproducibility.

Claims

1. A light-emitting device comprising:

a growth substrate made of a Group III nitride semiconductor;

a Group III nitride semiconductor layer stacked on the top surface of the growth substrate;

a support substrate joined to the semiconductor layer on the side opposite the growth substrate side of the semiconductor layer; and

a stopper layer formed between the growth substrate and the semiconductor layer, the stopper layer being formed of a material having a band gap higher than that of the material of the growth substrate, wherein the growth substrate has, at a center portion of the bottom surface, a cavity having a side surface perpendicular to or inclined with respect to the top or bottom surface of the growth substrate, so that the stopper layer or the semiconductor layer is exposed to the space defined by the cavity.

2. A light-emitting device according to claim 1, wherein the stopper layer is exposed to the space defined by the cavity.

3. A light-emitting device according to claim 1, wherein the stopper layer is formed of a Group III nitride semiconductor.

4. A light-emitting device according to claim 3, wherein the stopper layer is formed of AlGaN.

5. A light-emitting device according claim 4, wherein the stopper layer has an Al compositional proportion of 5 to 40%.

6. A light-emitting device according to claim 1, wherein the growth substrate is formed of GaN.

7. A light-emitting device according to claim 1, wherein the growth substrate is a c-plane substrate, and the top surface and the bottom surface of the substrate are a Ga-polar surface and an N-polar surface, respectively.

8. A light-emitting device according to claim 4, wherein the growth substrate is a c-plane substrate, and the top surface and the bottom surface of the substrate are a Ga-polar surface and an N-polar surface, respectively.

9. A light-emitting device according to claim 6, wherein the growth substrate is a c-plane substrate, and the top surface and the bottom surface of the substrate are a Ga-polar surface and an N-polar surface, respectively.

10. A method for producing a light-emitting device comprising a growth substrate made of Group III nitride semiconductor, and a Group III nitride semiconductor layer stacked on the top surface of the growth substrate, the method comprising:

forming, between the growth substrate and the semiconductor layer, a stopper layer exhibiting resistance to a wet etchant; and

wet-etching the bottom surface of the growth substrate until the stopper layer is exposed.

11. A method for producing a light-emitting device according to claim 10, wherein the stopper layer is formed of a material having a band gap higher than that of the material of the growth substrate, and the wet-etching is PEC etching employing light having a wavelength corresponding to an energy higher than the band gap of the material of the substrate, but lower than the band gap of the material of the stopper layer.

12. A method for producing a light-emitting device according to claim 10, wherein the stopper layer is formed of a Group III nitride semiconductor.

13. A method for producing a light-emitting device according to claim 12, wherein the stopper layer is formed of AlGaN.

14. A method for producing a light-emitting device according to claim 13, wherein the stopper layer has an Al compositional proportion of 5 to 40%.

15. A method for producing a light-emitting device according to any one of claim 10, wherein the growth substrate is formed of GaN.

16. A method for producing a light-emitting device according to claim 10, wherein the growth substrate is a c-plane substrate, and the top surface and the bottom surface of the substrate are a Ga-polar surface and an N-polar surface, respectively.

17. A method for producing a light-emitting device according to claim 11, wherein the growth substrate is a c-plane substrate, and the top surface and the bottom surface of the substrate are a Ga-polar surface and an N-polar surface, respectively.

18. A method for producing a light-emitting device according to claim 14, wherein the growth substrate is a c-plane substrate, and the top surface and the bottom surface of the substrate are a Ga-polar surface and an N-polar surface, respectively.

19. A method for producing a light-emitting device according to claim 10, wherein the wet etching is carried out for providing, at a center portion of the bottom surface of the growth substrate, a cavity having a side surface perpendicular to or inclined with respect to the top or bottom surface of the growth substrate, so that the stopper layer is exposed to the space defined by the cavity.

20. A method for producing a light-emitting device according to claim 16, wherein the wet etching is carried out for providing, at a center portion of the bottom surface of the growth substrate, a cavity having a side surface perpendicular to or inclined with respect to the top or bottom surface of the growth substrate, so that the stopper layer is exposed to the space defined by the cavity.