Light emitting devices having a roughened reflective bond pad and methods of fabricating light emitting devices having roughened reflective bond pads

• US 7,557,379 B2
• Filed: 05/19/2008
• Issued: 07/07/2009
• Est. Priority Date: 07/27/2004
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Bergmann, Michael John, Emerson, David Todd, Haberern, Kevin, Mieczkowski, Van
• Primary Examiner(s): SEFER, AHMED N
• Application Number:
  US12/123,137
• Publication Number:
  US 20080217641A1
• Time in Patent Office: 414 Days
• Field of Search: 257/79, 257 98- 99, 438/27
• US Class Current: 257/79
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/12036 PN diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

Light emitting devices include an active region of semiconductor material and a first contact on the active region. The first contact is configured such that photons emitted by the active region pass through the first contact. A photon absorbing wire bond pad is provided on the first contact. The wire bond pad has an area less than the area of the first contact. A reflective structure is disposed between the first contact and the wire bond pad such that the reflective structure has substantially the same area as the wire bond pad. A second contact is provided opposite the active region from the first contact. The reflective structure may be disposed only between the first contact and the wire bond pad. Methods of fabricating such devices are also provided.

Claims

1. A light emitting device, comprising:

an active region comprising semiconductor material;

a first contact on the active region;

a photon absorbing wire bond pad on the first contact, the wire bond pad having an area less than the area of the first contact;

a reflective structure disposed between the first contact and the wire bond pad and having an area that is less than the area of the first contact; and

a second contact opposite the active region from the first contact;

wherein the reflective structure comprises;

a roughened area of the first contact; and

a reflective metal layer on the roughened area of the first contact.

2. A light emitting device, comprising:

an active region comprising semiconductor material;

a first contact on the active region;

a photon absorbing wire bond pad on the first contact, the wire bond pad having an area less than the area of the first contact;

a reflective structure disposed between the first contact and the wire bond pad and having an area that is less than the area of the first contact; and

a second contact opposite the active region from the first contact;

wherein the reflective structure comprises a roughened area of the first contact and wherein the wire bond pad is directly on the first contact; and

wherein the reflective structure does not extend beyond the wire bond pad.

3. The light emitting device of claim 2 further comprising a p-type semiconductor material disposed between the first contact and the active region.

4. The light emitting device of claim 2, further comprising an n-type semiconductor material between the first contact and the active region.

5. The light emitting device of claim 2, wherein the active region comprises a Group III-nitride based active region.

6. The light emitting device of claim 2 wherein the reflective structure comprises a layer of reflective metal.

7. The light emitting device of claim 2, wherein the reflective structure is self-aligned with the wire bond pad.

8. The light emitting device of claim 2, wherein the roughened area is self-aligned with the wire bond pad.

9. The light emitting device of claim 2, wherein the reflective structure has substantially the same area as the wire bond pad.

10. The light emitting device of claim 2, wherein the reflective structure is substantially congruent with the wire bond pad.

11. A method of fabricating a light emitting device, comprising:

forming an active region of semiconductor material;

forming a first contact on the active region;

forming a reflective structure on the first contact and having an area less than an area of the first contact

forming a photon absorbing wire bond pad on reflective structure, the wire bond pad having an area less than the area of the first contact; and

forming a second contact opposite the active region from the first contact;

wherein forming a reflective structure comprises roughening an area of the first contact; and

wherein forming a reflective structure and forming a wire bond pad comprises;

forming a mask layer on the first contact, the mask layer having an opening that exposes a portion of the first contact corresponding to the location of the wire bond pad on the first contact;

depositing a reflective metal layer in the opening of the mask layer; and

forming the wire bond pad on the reflective metal layer in the opening of the mask layer.

12. A method of fabricating a light emitting device, comprising:

forming an active region of semiconductor material;

forming a first contact on the active region;

forming a reflective structure on the first contact and having an area less than an area of the first contact

forming a photon absorbing wire bond pad on reflective structure, the wire bond pad having an area less than the area of the first contact; and

forming a second contact opposite the active region from the first contact;

wherein forming a reflective structure comprises roughening an area of the first contact and wherein forming a wire bond pad comprises forming a wire bond pad directly on the first contact; and

wherein roughening an area of the first contact and forming a wire bond pad comprises;

forming a mask layer on the first contact, the mask layer having an opening that exposes a portion of the first contact corresponding to the location of the wire bond pad on the first contact;

roughening the portion of the first contact exposed by the opening of the mask layer; and

forming the wire bond pad on the roughened portion of the first contact in the opening of the mask layer.

13. A method of fabricating a light emitting device, comprising:

forming an active region of semiconductor material;

forming a first contact on the active region;

forming a reflective structure on the first contact and having an area less than an area of the first contact

forming a photon absorbing wire bond pad on reflective structure, the wire bond pad having an area less than the area of the first contact; and

forming a second contact opposite the active region from the first contact;

wherein forming a reflective structure comprises;

forming a roughened area of the first contact; and

forming a reflective metal layer on the roughened area of the first contact.

14. The method of claim 13, further comprising forming a p-type semiconductor material disposed between the first contact and the active region.

15. The method of claim 13, further comprising forming an n-type semiconductor material between the first contact and the active region.

16. The method of claim 13, wherein forming an active region comprises forming a Group III-nitride based active region.

17. The method of claim 13, wherein the reflective structure does not extend beyond the wire bond pad.

18. The method of claim 13, wherein the reflective structure has substantially the same area as the wire bond pad.

19. The method of claim 13, wherein the reflective structure is substantially congruent with the wire bond pad.