III-Phosphide and III-Arsenide flip chip light-emitting devices

• US 20020093023A1
• Filed: 03/11/2002
• Published: 07/18/2002
• Est. Priority Date: 06/03/1997
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Krames, Michael R., Martin, Paul S., Steranka, Frank M., Camras, Michael D., Steigerwald, Daniel A., Stockman, Stephen A., Ludowise, Michael J., Kish, Fred A.
• Granted Patent: US 6,784,463 B2
• Time in Patent Office: Days
• US Class Current: 257/94
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05611 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05639 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05655 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/05664 Palladium [Pd] as principal constituent
• CPC Class Codes: H01L 2224/05666 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/05669 Platinum [Pt] as principal constituent
• CPC Class Codes: H01L 2224/05671 Chromium [Cr] as principal constituent
• CPC Class Codes: H01L 2224/05684 Tungsten [W] as principal constituent
• CPC Class Codes: H01L 2224/06102 the bonding areas being at different heights
• CPC Class Codes: H01L 2224/0615 Mirror array, i.e. array having only a reflection symmetry, i.e. bilateral symmetry
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/1703 Bump connectors having different sizes, e.g. different diameters, heights or widths
• CPC Class Codes: H01L 24/03 Manufacturing methods
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/06 of a plurality of bonding areas
• 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 33/02 : characterised by the semiconductor bodies
• CPC Class Codes: H01L 33/08 : with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/14 : with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/20 : with a particular shape, e.g. curved or truncated substrate

Abstract

A light-emitting semiconductor device includes a stack of layers including an active region. The active region includes a semiconductor selected from the group consisting of III-Phosphides, III-Arsenides, and alloys thereof. A superstrate substantially transparent to light emitted by the active region is disposed on a first side of the stack. First and second electrical contacts electrically coupled to apply a voltage across the active region are disposed on a second side of the stack opposite to the first side. In some embodiments, a larger fraction of light emitted by the active region exits the stack through the first side than through the second side. Consequently, the light-emitting semiconductor device may be advantageously mounted as a flip chip to a submount, for example.

Claims

1. A light-emitting semiconductor device comprising:

a stack of layers including an active region, said active region comprising a semiconductor selected from the group consisting of III-Phosphides, III-Arsenides, and alloys thereof;

a superstrate disposed on a first side of said stack, said superstrate substantially transparent to light emitted by said active region; and

a first electrical contact and a second electrical contact electrically coupled to apply a voltage across said active region, said first electrical contact and said second electrical contact disposed on a second side of said stack opposite to said first side.

2. The light-emitting semiconductor device of claim 1, wherein a larger fraction of light emitted by said active region exits said stack through said first side than through said second side.

3. The light-emitting semiconductor device of claim 1, wherein said superstrate is formed from a material having a refractive index greater than about 1.8 at a wavelength of light emitted by said active region.

4. The light-emitting semiconductor device of claim 1, wherein said superstrate has a resistivity greater than about 0.05 Ohm-centimeters.

5. The light-emitting semiconductor device of claim 1, wherein said superstrate is formed from a semiconductor material.

6. The light-emitting semiconductor device of claim 5, wherein said superstrate is formed from a semiconductor material selected from the group consisting of III-Phosphides, III-Arsenides, II-VI semiconductors, and SiC.

7. The light-emitting semiconductor device of claim 5, wherein said semiconductor material is GaP.

8. The light-emitting device of claim 5, wherein said semiconductor material is undoped.

9. The light-emitting device of claim 1, wherein said superstrate is formed from a dielectric material.

10. The light-emitting device of claim 9, wherein said dielectric material is selected from diamond, yttrium aluminum garnet, metal oxides, metal fluorides, optical glasses, chalcogenide glasses, phosphides, arsenides, and nitrides.

11. The light-emitting device of claim 9, wherein said dielectric material comprises sapphire.

12. The light-emitting device of claim 1, wherein said superstrate has a surface that forms an acute angle with said first side of said stack.

13. The light-emitting device of claim 1, wherein said superstrate has a surface that forms an obtuse angle with said first side of said stack.

14. The light-emitting device of claim 1, wherein said superstrate has a curved surface.

15. The light-emitting device of claim 1, further comprising a bonded interface disposed between said active region and said superstrate.

16. The light-emitting device of claim 15, wherein said superstrate is directly bonded to a semiconductor layer included in said stack.

17. The light-emitting device of claim 1, further comprising at least one bonding layer disposed between said active region and said superstrate.

18. The light-emitting device of claim 17, wherein said bonding layer is formed from a material having a refractive index greater than about 1.5 at a wavelength of light emitted by said active region.

19. The light-emitting device of claim 1, wherein at least one of said electrical contacts is highly reflective to light emitted by said active region.

20. The light-emitting device of claim 19, wherein said one of said electrical contacts comprises:

a patterned semiconductor layer disposed on portions of said second side of said stack;

a plurality of ohmic contacts disposed on said patterned semiconductor layer; and

a reflective metal layer disposed on portions of said second side of said stack not covered by said patterned semiconductor layer.

21. The light-emitting device of claim 1, wherein said first electrical contact surrounds said second electrical contact.

22. The light-emitting device of claim 1, further comprising at least one layer highly reflective to light emitted by said active region located to reflect said light toward said superstrate.

23. The light-emitting device of claim 1, further comprising an interface textured to scatter light emitted by said active region.

24. The light-emitting device of claim 1, further comprising a lens attached to said superstrate.

25. The light-emitting device of claim 1, wherein an area of said active region is greater than about 0.2 square millimeters.

26. The light-emitting device of claim 1, wherein an area of said active region is greater than about 1.0 square millimeters.

27. The light-emitting device of claim 1, wherein said stack of layers, said superstrate, and said electrical contacts are configured to allow said light-emitting semiconductor device to operate at an input power exceeding 0.5 Watts.

28. The light-emitting device of claim 1, further comprising a composition graded layer substantially latticed matched to said superstrate and substantially lattice matched to said stack.

30. The array of claim 29, wherein at least a subset of said light-emitting semiconductor devices emits red light.

31. The array of claim 29, wherein at least a subset of said light-emitting semiconductor devices emits amber light.

32. The array of claim 29, wherein at least a subset of said light-emitting semiconductor devices emits green light.

33. The array of claim 29, wherein at least a subset of said light-emitting semiconductor devices emits blue light.

34. The array of claim 33, wherein said active regions of said light-emitting semiconductor devices that emit blue light include a III-Nitride semiconductor.

35. The array of claim 29, wherein light emitted by said light-emitting devices combine to produce white light.

36. The array of claim 29, wherein at least a subset of said light-emitting semiconductor devices are coated with one or more luminescent materials that convert light of a wavelength emitted by said active regions to at least another wavelength.

38. The method of claim 37, further comprising bonding said superstrate to said stack.

39. The method of claim 37, further comprising growing said superstrate on said stack.

40. The method of claim 37, wherein the act of removing said portion of said host substrate precedes the act of attaching said superstrate to said structure.

41. The method of claim 37, wherein the act of attaching said superstrate to said structure precedes the act of removing said portion of said host substrate.

29. An array of light-emitting devices comprising:

a substrate having a surface; and

a plurality of light-emitting semiconductor devices, each of which comprises a stack of semiconductor layers including an active region, a superstrate disposed on a first side of said stack and substantially transparent to light emitted by said active region, and a first electrical contact and a second electrical contact disposed on a second side of said stack opposite to said first side, said light-emitting semiconductor devices disposed above said surface of said substrate with their superstrates facing away from said substrate;

wherein said active regions of at least a subset of said light-emitting semiconductor devices include a semiconductor selected from the group consisting of III-Phosphides, III-Arsenides, and alloys thereof.

37. A method of forming a light-emitting semiconductor device, said method comprising:

forming a structure including a stack of semiconductor layers overlying a host substrate, said stack including an active region, said active region comprising a semiconductor selected from the group consisting of III-Phosphides, III-Arsenides, and alloys thereof;

attaching a superstrate to a first side of said structure, said superstrate substantially transparent to light emitted by said active region;

removing at least a portion of said host substrate; and

forming a first electrical contact and a second electrical contact on a second side of said structure opposite to said first side, said first electrical contact and said second electrical contact electrically coupled to apply a voltage across said active region.