Bond pad design for enhancing light extraction from LED chips

• US 8,384,115 B2
• Filed: 08/01/2008
• Issued: 02/26/2013
• Est. Priority Date: 08/01/2008
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Li, Ting
• Primary Examiner(s): Warren, Matthew E
• Application Number:
  US12/185,031
• Publication Number:
  US 20100025719A1
• Time in Patent Office: 1,670 Days
• Field of Search: 257/91, 257/95, 257/99, 257/E33.002, 257/E33.005, 257/E33.006, 257/E33.057, 257/E33.065
• 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

wherein said semiconductor structure is shaped to define at least one trench proximate to an edge of said bond pad and substantially separating areas of said semiconductor structure beneath said bond pad from the rest of said semiconductor structure;

wherein each layer of said semiconductor structure beneath said bond pad is contiguous with a corresponding layer of the rest of said semiconductor structure, such that a connecting portion between said semiconductor structure beneath said bond pad and the rest of said semiconductor structure is narrower than the 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 structure.

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 structure.

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 structure 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.