Light-emitting devices having coplanar electrical contacts adjacent to a substrate surface opposite an active region and methods of forming the same

• US 20040217360A1
• Filed: 04/06/2004
• Published: 11/04/2004
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Negley, Gerald H.
• Granted Patent: US 7,714,345 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body

Abstract

A light-emitting device includes a substrate having first and second opposing surfaces. An active region is on the first surface and first and second electrical contacts are adjacent to the second surface and are conductively coupled to the active region. In other embodiments, a light-emitting device includes a substrate having first and second opposing Surfaces. An active region is on the first surface and includes a first active layer having a first conductivity type on the first surface and a second active layer having a second conductivity type on the first active layer. A first electrical contact is adjacent to the second surface. A contact plug extends through the substrate and the active region and couples the first electrical contact to the second active layer. A second electrical contact is coupled to the substrate at the second surface.

Claims

1. A light-emitting device, comprising:

a substrate having first and second opposing surfaces;

an active region comprising a first active layer having a first conductivity type on the first surface and a second active layer having a second conductivity type on the first active layer;

a first electrical contact adjacent to the second surface;

a contact plug extending through the substrate and the active region that couples the first electrical contact to the second active layer; and

a second electrical contact that is coupled to the substrate at the second surface.

2. The light-emitting device of claim 1, further comprising:

a dielectric spacer on sides of the contact plug that separate the contact plug from the substrate and the first active layer.

3. The light-emitting device of claim 2, wherein the dielectric spacer comprises spin-on-glass, a polyimide, silicon dioxide and/or silicon nitride.

4. The light-emitting device of claim 1, further comprising:

an ohmic contact layer on the second active layer, the contact plug extending through the second active layer to contact the ohmic contact layer.

5. The light-emitting device of claim 4, wherein the ohmic contact layer comprises at least one of TiN, platinum, nickel/gold, nickel oxide/gold, nickel oxide/platinum, Ti, and titanium/gold.

6. The light-emitting device of claim 5, wherein the ohmic contact layer has a thickness between about 10 Å

and about 100 Å

.

7. The light-emitting device of claim 4, wherein the ohmic contact layer is at least partially transparent.

8. The light-emitting device of claim 1, further comprising:

a buffer layer between the active region and the substrate, the contact plug extending through the buffer layer.

9. The light-emitting device of claim 8, wherein the buffer layer comprises aluminum nitride.

10. The light-emitting device of claim 1, wherein the substrate comprises SiC.

11. The light-emitting device of claim 1, wherein the contact plug comprises gold, siler, a gold alloy, and/or a silver alloy.

12. The light-emitting device of claim 1, wherein the first conductivity type is n-type, and wherein the second electrical contact comprises at least one of aluminum and titanium.

13. The light-emitting device of claim 1, wherein the second conductivity type is p-type, and wherein the first electrical contact comprises at least one of platinum, nickel, and titanium/gold.

14. The light-emitting device of claim 1, wherein the first active layer comprises GaN.

15. The light-emitting device of claim 1, wherein the second active layer comprises GaN.

16. A light-emitting device, comprising:

a substrate having first and second opposing surfaces;

an active region on the first surface;

first and second electrical contacts adjacent to the second surface that are conductively coupled to the active region.

17. The light-emitting device of claim 16, wherein the active region comprises:

a first active layer having a first conductivity type on the first surface; and

a second active layer having a second conductivity type on the first active layer.

18. The light-emitting device of claim 17, further comprising:

a contact plug extending through the substrate and the active region that couples the first electrical contact to the second active layer.

19. The light-emitting device of claim 18, further comprising:

a dielectric spacer on sides of the contact plug that separate the contact plug from the substrate and the first active layer.

20. The light-emitting device of claim 19, wherein the dielectric spacer comprises spin-on-glass, a polyimide, silicon dioxide, and/or silicon nitride.

21. The light-emitting device of claim 18, further comprising:

an ohmic contact layer on the second active layer, the contact plug extending through the second active layer to contact the ohmic contact layer.

22. The light-emitting device of claim 21, wherein the ohmic contact layer comprises at least one of TiN, platinum, nickel/gold, nickel oxide/gold, nickel oxide/platinum, Ti, and titanium/gold.

23. The light-emitting device of claim 22, wherein the ohmic contact layer has a thickness between about 10 Å

and about 100 Å

.

24. The light-emitting device of claim 21, wherein the ohmic contact layer is at least partially transparent.

25. The light-emitting device of claim 18, further comprising:

a buffer layer between the active region and the substrate, the contact plug extending through the buffer layer.

26. The light-emitting device of claim 25, wherein the buffer layer comprises aluminum nitride.

27. The light-emitting device of claim 18, wherein the contact plug comprises gold, silver, a gold alloy, and/or a silver alloy.

28. The light-emitting device of claim 17, wherein the first conductivity type is n-type, and wherein the second electrical contact comprises at least one of aluminum and titanium.

29. The light-emitting device of claim 17, wherein the second conductivity type is p-type, and wherein the first electrical contact comprises at least one of platinum, nickel, and titanium/gold.

30. The light-emitting device of claim 17, wherein the first active layer comprises GaN.

31. The light-emitting device of claim 17, wherein the second active layer comprises GaN.

32. The light-emitting device of claim 16, wherein the substrate comprises SiC.

33. A method of forming a light-emitting device, comprising:

forming a first active layer having a first conductivity type on a first surface a substrate having first and second opposing surfaces;

forming a second active layer having a second conductivity type on the first active layer, the first and second active layers comprising an active region;

forming a via through the substrate and the active region;

forming a contact plug in the via;

forming a first electrical contact adjacent to the second surface, the contact plug coupling the first electrical contact to the second active layer; and

forming a second electrical contact that is coupled to the substrate at the second surface.

34. The method of claim 33, further comprising:

forming a dielectric spacer on sides of the contact plug that separate the contact plug from the substrate and the first active layer.

35. The method of claim 34, wherein forming the dielectric spacer comprises:

filling at least a portion of the via with a dielectric material;

forming a mask on the second surface; and

etching the dielectric material through the mask.

36. The method of claim 33, further comprising:

forming an ohmic contact layer on the second active layer, the contact plug extending through the second active layer to contact the ohmic contact layer.

37. The method of claim 33, wherein forming the via comprises:

etching the substrate using the ohmic contact layer as an etch stop.

38. The method of claim 37, wherein etching the substrate is performed using at least one of the following etching techniques:

wet etching, dry etching, and micro-machining.

39. The method of claim 33, further comprising:

forming a buffer layer between the active region and the substrate, the contact plug extending through the buffer layer.

40. The method of claim 33, wherein forming the contact plug comprises:

plating the via with gold, silver, a gold alloy, and/or a silver alloy.

41. A method of forming a light-emitting device, comprising:

forming an active region on a first surface of a substrate having first and second opposing surfaces;

forming first and second electrical contacts adjacent to the second surface that are conductively coupled to the active region.

42. The method of claim 41, wherein forming the active region comprises:

forming a first active layer having a first conductivity type on the first surface; and

forming a second active layer having a second conductivity type on the first active layer.

43. The method of claim 42, further comprising:

forming a contact plug extending through the substrate and the active region that couples the first electrical contact to the second active layer.

44. The method of claim 43, further comprising:

forming a dielectric spacer on sides of the contact plug that separate the contact plug from the substrate and the first active layer.

45. The method of claim 43, further comprising:

forming an ohmic contact layer on the second active layer, the contact plug extending through the second active layer to contact the ohmic contact layer.

46. The method of claim 43, further comprising:

forming a buffer layer between the active region and the substrate, the contact plug extending through the buffer layer.