Flip-chip bonding of light emitting devices and light emitting devices suitable for flip-chip bonding

• US 6,888,167 B2
• Filed: 06/27/2002
• Issued: 05/03/2005
• Est. Priority Date: 07/23/2001
• Status: Expired due to Term

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Microwave, LLC, CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Andrews, Peter S., Negley, Gerald H., Slater, David B. Jr., Edmond, John, Raffetto, Mark, Bharathan, Jayesh, Mohammed, Anwar
• Primary Examiner(s): Coleman, W. David
• Application Number:
  US10/185,252
• Publication Number:
  US 20030045015A1
• Time in Patent Office: 1,041 Days
• Field of Search: 257/81, 257/79, 257/91, 257/676, 257/E33.001, 257/E33.026, 257/E33.03, 257/E33.055, 257/E33.062
• US Class Current: 257/81
• CPC Class Codes: H01L 2224/04026 Bonding areas specifically adapted for layer connectors
• CPC Class Codes: H01L 2224/26175 Flow barriers
• CPC Class Codes: H01L 2224/291 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01057 Lanthanum [La]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/014 Solder alloys
• CPC Class Codes: H01L 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

Light emitting device die having a mesa configuration on a substrate and an electrode on the mesa are attached to a submount in a flip-chip configuration by forming predefined pattern of conductive die attach material on at least one of the electrode and the submount and mounting the light emitting device die to the submount. The predefined pattern of conductive die attach material is selected so as to prevent the conductive die attach material from contacting regions of having opposite conductivity types when the light emitting device die is mounted to the submount. The predefined pattern of conductive die attach material may provide a volume of die attach material that is less than a volume defined by an area of the electrode and a distance between the electrode and the submount. Light emitting device dies having predefined patterns of conductive die attach material are also provided. Light emitting devices having a gallium nitride based light emitting region on a substrate, such as a silicon carbide substrate, may also be mounted in a flip-chip configuration by mounting an electrode of the gallium nitride based light emitting region to a submount utilizing a B-stage curable die epoxy. Light emitting device dies having a B-stage curable die epoxy are also provided.

Claims

1. A light emitting device die, comprising:

a conducting substrate;

a gallium nitride based active region on the conducting substrate;

a first electrode on the nitride based active region opposite the conducting substrate, the first electrode and the gallium nitride based active region forming a mesa having sidewalls;

a second electrode on the conducting substrate opposite the gallium nitride active region; and

a predefined pattern of conductive die attach material on the first electrode opposite the gallium nitride active region that substantially prevents the conductive die attach material from contacting at least one of the sidewalls of the mesa and the substrate when the light emitting device die is mounted to a submount.

2. The die of claim 1, wherein the conducting substrate comprises a silicon carbide substrate.

3. The die of claim 1, wherein the predefined pattern of conductive die attach material provides a volume of die attach material that is less than a volume defined by an area of the first electrode and a distance between the first electrode and the submount.

4. The die of claim 1, wherein the predefined pattern comprises a single nodule of conductive die attach material on the first electrode.

5. The die of claim 1, wherein the predefined pattern comprises a plurality of bumps of conductive die attach material on the first electrode.

6. The die of claim 1, wherein the predefined pattern comprises a plurality of lines of conductive die attach material on the first electrode.

7. The die of claim 1, wherein the predefined pattern comprises a criss-cross pattern of conductive die attach material on the first electrode.

8. The die of claim 1, wherein the conductive die attach material comprises at least one of a B-stage curable die epoxy, a solder paste, a pattern of solder bumps, and/or a conductive polymer.

9. The die of claim 1, further comprising a submount, wherein the first electrode is mounted to the submount by the predefined pattern of conductive die attach material.

10. A light emitting device die, comprising:

a substrate;

a gallium nitride based active region on the substrate;

a first electrode on the nitride based active region opposite the substrate;

a B-stage conductive epoxy on the first electrode opposite the gallium nitride active region.

11. The die of claim 10, wherein the first electrode and the gallium nitride based active region form a mesa having sidewalls.

12. The die of claim 10, wherein the substrate is a conducting substrate, the die further comprising a second electrode on the conducting substrate opposite the gallium nitride active region.

13. The die of claim 10, wherein the substrate is an insulating substrate, the die further comprising a second electrode on the conducting substrate on a same side of the substrate as the gallium nitride active region.

14. The die of claim 10, wherein the conducting substrate comprises a silicon carbide substrate.

15. The die of claim 10, wherein the B-stage conductive epoxy is on the first electrode in a predefined pattern.

16. The die of claim 15, wherein the predefined pattern of conductive die attach material provides a volume of die attach material that is less than a volume defined by an area of the first electrode and a distance between the first electrode and the submount.

17. The die of claim 15, wherein the predefined pattern comprises a single nodule of B-stage conductive epoxy on the first electrode.

18. The die of claim 15, wherein the predefined pattern comprises a plurality of bumps of B-stage conductive epoxy on the first electrode.

19. The die of claim 15, wherein the predefined pattern comprises a plurality of lines of B-stage conductive epoxy on the first electrode.

20. The die of claim 15, wherein the predefined pattern comprises a criss-cross pattern of B-stage conductive epoxy on the first electrode.

21. The die of claim 10, further comprising a submount, wherein the first electrode is mounted to the submount by the B-stage conductive epoxy.

22. A light emitting device die for flip-chip mounting, comprising:

a gallium nitride based active region having at least one region of a first conductivity type;

a first electrode electrically coupled to the gallium nitride based active region;

a region of semiconductor material of a second conductivity type electrically coupled to the gallium nitride based active region, the second conductivity type being opposite to the first conductivity type; and

a predefined pattern of conductive die attach material on the first electrode opposite the gallium nitride active region, the predefined pattern being configured to substantially prevent the conductive die attach material from contacting the region of semiconductor material of a second conductivity type when the light emitting device die is mounted to a submount.

23. The die of claim 22, further comprising a second electrode on the region of semiconductor material of a second conductivity type.

24. The die of claim 23, further comprising a substrate, wherein the gallium nitride based active region is on the substrate.

25. The die of claim 24, wherein the first electrode and the second electrode are on opposite sides of the substrate.

26. The die of claim 24, wherein the first electrode and the second electrode are on a same side of the substrate.

27. The die of claim 24, wherein the substrate comprises a silicon carbide substrate.

28. The die of claim 22, wherein the predefined pattern of conductive die attach material provides a volume of die attach material that is less than a volume defined by an area of the first electrode and a distance between the first electrode and the submount.

29. The die of claim 22, wherein the predefined pattern comprises a single nodule of conductive die attach material on the first electrode.

30. The die of claim 22, wherein the conductive die attach material comprises solder.

31. The die of claim 22, wherein the predefined pattern comprises a plurality of bumps of conductive die attach material on the first electrode.

32. The die of claim 22, wherein the predefined pattern comprises a plurality of lines of conductive die attach material on the first electrode.

33. The die of claim 22, wherein the predefined pattern comprises a criss-cross pattern of conductive die attach material on the first electrode.

34. The die of claim 22, wherein the conductive die attach-material comprises at least one of a B-stage curable die epoxy, a solder paste, a pattern of solder bumps, and/or a conductive polymer.

35. The die of claim 22, further comprising a submount, wherein the first electrode is mounted to the submount by the predefined pattern of conductive die attach material.