BOND PAD DESIGN FOR ENHANCING LIGHT EXTRACTION FROM LED CHIPS

• US 20100025719A1
• Filed: 08/01/2008
• Published: 02/04/2010
• Est. Priority Date: 08/01/2008
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Li, Ting
• Granted Patent: US 8,384,115 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

An improved bond pad design for increased light extraction efficiency for use in light emitting diodes (LEDs) and LED packages. Embodiments of the present invention incorporate a structure that physically isolates the bond pads from the primary emission surface, forcing the current to flow away from the bond pads first before traveling down into the semiconductor material toward the active region. This structure reduces the amount of light that is generated in the area near the bond pads, so that less of the generated light is trapped underneath the bond pads and absorbed.

Claims

1. A light emitting diode (LED) chip device, comprising:

a light emitting semiconductor structure;

at least one bond pad disposed on said semiconductor structure; and

at least one trench in said semiconductor structure proximate to at least one edge of said bond pad.

2. The LED chip device of claim 1, further comprising at least one current spreading conductor electrically contacting said at least one bond pad and said semiconductor device.

3. The LED chip device of claim 1, further comprising a passivation layer that covers the sidewalls of said semiconductor structure.

4. The LED chip device of claim 1, said semiconductor structure comprising an n-type layer, a p-type layer, and an active region interposed between said n-type and p-type layers.

5. The LED chip device of claim 4, further comprising a p-contact in electrical contact with said p-type layer and opposite a primary emission surface of said semiconductor device.

6. The LED chip device of claim 5, further comprising a current blocking layer interposed between said p-contact and said p-type layer beneath said at least one bond pad.

7. The LED chip device of claim 1, wherein said at least one bond pad is substantially circular.

8. The LED chip device of claim 1, wherein said at least one bond pad is substantially rectangular.

9. The LED chip device of claim 1, wherein said at least one trench is backfilled with a filler material.

10. The LED package of claim 1, wherein a primary emission surface of said semiconductor device is substantially rectangular.

11. The LED chip device of claim 10, said at least one bond pad comprising two bond pads disposed near respective adjacent corners of said primary emission surface, said at least one trench comprising two trenches proximate to the edges of each of said two bond pads.

12. The LED chip device of claim 1, said semiconductor device comprising gallium nitride (GaN) materials.

13. A light emitting diode (LED) device, comprising:

a light emitting semiconductor structure disposed on a mount surface, said semiconductor structure comprising a primary emission surface having a generally rectangular shape, said semiconductor structure shaped to define two peninsular bond pad mount regions in adjacent corners of said primary emission surface, said bond pad mount regions isolated from the rest of said semiconductor structure by trenches;

two bond pads disposed, one each, on said bond pad mount regions; and

a current spreading conductor disposed on said primary emission surface and in electrical contact with said bond pads, said current spreading conductor forming a pattern on said primary emission surface.

14. The LED device of claim 13, further comprising a passivation layer that covers the sidewalls of said semiconductor structure and an edge portion of said primary emission surface.

15. The LED device of claim 13, said semiconductor structure comprising an n-type layer, a p-type layer, and an active region interposed between said n-type and p-type layers.

16. The LED device of claim 15, further comprising a p-contact in electrical contact with said p-type layer and opposite said primary emission surface.

17. The LED device of claim 13, further comprising a current blocking layer disposed on said semiconductor structure in an area opposite each of said bond pads.

18. The LED device of claim 13, wherein said peninsular bond pad mount regions are substantially circular.

19. The LED device of claim 13, wherein said peninsular bond pad mount regions are substantially rectangular.

20. The LED device of claim 13, wherein said trenches are backfilled with a filler material.

21. The LED device of claim 13, said semiconductor structure comprising gallium nitride (GaN) materials.

22. A light emitting device (LED) package, comprising:

an LED chip, comprising;

a light emitting semiconductor structure;

at least one bond pad disposed on a primary emission surface of said semiconductor structure, said semiconductor structure shaped to define trenches that partially surround a portion of said semiconductor structure directly contacting said bond pad; and

a plurality of current spreading conductors electrically contacting said at least one bond pad and said primary emission surface;

a secondary mount, said LED chip mounted thereon; and

at least two package leads connected to provide an electrical connection to said LED chip.

23. The LED package of claim 22, further comprising a reflector cup disposed to reflect light that is emitted laterally from said LED chip.

24. The LED package of claim 22, further comprising a lens disposed proximate to said LED chip, said lens interacting with substantially all of the light emitted from said LED chip.

25. The LED package of claim 22, said LED chip comprising a wavelength conversion layer disposed to convert the wavelength of a portion of the light emitted from said semiconductor structure.

26. The LED package of claim 22, said LED chip further comprising a passivation layer that covers the sidewalls of said semiconductor structure and an edge portion of said primary emission surface.

27. The LED package of claim 22, said semiconductor structure comprising an n-type layer, a p-type layer, and an active region interposed between said n-type and p-type layers.

28. The LED package of claim 22, said LED chip further comprising a p-contact in electrical contact with said p-type layer and opposite said primary emission surface.

29. The LED package of claim 22, said LED chip further comprising a current blocking layer interposed between said p-contact and said p-type layer beneath said at least one bond pad.

30. The LED package of claim 22, wherein said at least one bond pad is substantially circular.

31. The LED package of claim 22, wherein said at least one bond pad is substantially rectangular.

32. The LED package of claim 22, said at least one bond pad comprising two bond pads disposed near respective adjacent corners of said primary emission surface.

33. The LED package of claim 22, said semiconductor device comprising gallium nitride (GaN) materials.