Light emitting diodes including pedestals

• US 7,026,659 B2
• Filed: 06/03/2004
• Issued: 04/11/2006
• Est. Priority Date: 02/01/2001
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Ibbetson, James, Swoboda, Charles M., Keller, Bernd, Slater, David B. Jr., Tarsa, Eric J., Thibeault, Brian, Glass, Robert C.
• Primary Examiner(s): JACKSON JR, JEROME
• Application Number:
  US10/859,635
• Publication Number:
  US 20040217362A1
• Time in Patent Office: 677 Days
• Field of Search: 257/98, 257/99
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/32014 the layer connector being smaller than the bonding area, e.g. bond pad
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/60 Reflective elements
• 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 diodes include a substrate having first and second opposing faces and that is transparent to optical radiation in a predetermined wavelength range and that is patterned to define, in cross-section, a plurality of pedestals that extend into the substrate from the first face towards the second face. A diode region on the second face is configured to emit light in the predetermined wavelength range, into the substrate upon application of voltage across the diode region. A mounting support on the diode region, opposite the substrate is configured to support the diode region, such that the light that is emitted from the diode region into the substrate, is emitted from the first face upon application of voltage across the diode region. The first face of the substrate may include therein a plurality of grooves that define the plurality of triangular pedestals in the substrate. The grooves may include tapered sidewalls and/or a beveled floor. The first face of the substrate also may include therein an array of via holes. The via holes may include tapered sidewalls and/or a floor.

Claims

1. A light emitting diode comprising:

a substrate having first and second opposing faces, that is transparent to optical radiation in a predetermined wavelength range and that is patterned to define, in cross-section, a plurality of pedestals that extend into the substrate from the first face towards the second face;

a diode region on the second face that is configured to emit light in the predetermined wavelength range into the substrate that is transparent to optical radiation in the predetermined wavelength range, upon application of voltage across the diode region;

a mounting support on the diode region opposite the substrate that is transparent to optical radiation in the predetermined frequency range, the mounting support being configured to support the diode region such that the light that is emitted from the diode region into the substrate that is transparent to optical radiation in the predetermined wavelength range, is emitted from the plurality of pedestals, upon application of voltage across the diode region;

a reflector between the mounting support and the diode region, that is configured to reflect light that is emitted from the diode region back into the diode region, through the substrate that is transparent to optical radiation in the predetermined wavelength range and from the plurality of pedestals, upon application of voltage across the diode region; and

a transparent electrode between the diode region and the reflector.

3. A light emitting diode according to claim 1 wherein the transparent electrode comprises a layer of nickel/gold, nickel oxide/gold, nickel oxide/platinum, titanium and/or titanium/gold.

5. A light emitting diode according to claim 1 further comprising:

a barrier region between the reflector and the mounting support; and

a bonding region between the barrier region and the mounting support.

7. A light emitting diode according to claim 5 wherein the bonding region comprises gold, indium, solder and/or braze.

8. A light emitting diode according to claim 1 further comprising:

an optical element adjacent the first face, opposite the diode region.

9. A light emitting diode according to claim 1 wherein the first face of the substrate includes therein at least one groove that defines, in cross-section, the plurality of pedestals in the substrate.

10. A light emitting diode according to claim 9 wherein the pedestals are triangular pedestals.

11. A light emitting diode according to claim 9 wherein the grooves include tapered and/or curved sidewalls.

12. A light emitting diode according to claim 9 wherein the grooves include a beveled and/or curved floor.

13. A light emitting diode according to claim 11 wherein the grooves include a beveled and/or curved floor.

14. A light emitting diode according to claim 9 wherein the first and second faces of the substrate comprise square perimeters.

15. A light emitting diode according to claim 9 wherein the first face of the substrate comprises a textured surface.

16. A light emitting diode according to claim 1 wherein the first face of the substrate includes therein an array of via holes that defines, in cross-section, the plurality of pedestals in the substrate.

17. A light emitting diode according to claim 16 wherein the via holes include tapered and/or curved sidewalls.

18. A light emitting diode according to claim 16 wherein the via holes include a flat, beveled and/or curved floor.

19. A light emitting diode according to claim 17 wherein the via holes include a flat, beveled and/or curved floor.

20. A light emitting diode according to claim 16 wherein the first and second faces of the substrate comprise square perimeters.

21. A light emitting diode according to claim 16 wherein the first face of the substrate comprises a textured surface.

22. A light emitting diode according to claim 16 wherein the array of via holes comprises an array of tapered and/or curved via holes.

23. A light emitting diode according to claim 1 wherein the diode region comprises a peripheral portion, at least one central portion that is enclosed by the peripheral portion and at least one emission region that is confined to within the at least one central portion and does not extend onto the peripheral portion.

24. A light emitting diode according to claim 1 further comprising:

a plurality of emission regions on the diode region, a respective one of which is confined to within a respective one of the pedestals and does not extend beyond the respective one of the pedestals.

25. A light emitting diode according to claim 9 further comprising:

a plurality of electrodes on the diode region, a respective one of which is confined to within a respective one of the pedestals and does not extend beyond the respective one of the pedestals.

26. A light emitting diode according to claim 16 further comprising:

at least one electrode on the diode region that does not overlap the via holes.

27. A light emitting diode according to claim 1, wherein the substrate comprises silicon carbide and wherein the diode region comprises gallium nitride.

2. A light emitting diode comprising:

a substrate having first and second opposing faces, that is transparent to optical radiation in a predetermined wavelength range and that is patterned to define, in cross-section, a plurality of pedestals that extend into the substrate from the first face towards the second face;

a diode region on the second face that is configured to emit light in the predetermined wavelength range into the substrate that is transparent to optical radiation in the predetermined wavelength range upon application of voltage across the diode region;

a mounting support on the diode region, opposite the substrate that is transparent to optical radiation in the predetermined frequency range, the mounting support being configured to support the diode region such that the light that is emitted from the diode region into the substrate that is transparent to optical radiation in the indetermined wavelength range, is emitted from the plurality of pedestals, upon application of voltage across the diode region; and

a reflector between the mounting support and the diode region, that is configured to reflect light that is emitted from the diode region back into the diode region, through the substrate that is transparent to optical radiation in the predetermined wavelength range and from the plurality of pedestals, upon application of voltage across the diode region;

wherein the reflector comprises a layer of at least one reflective metal.

28. A light emitting diode according to claim 2 further comprising:

a transparent electrode between the diode region and the reflector.

29. A light emitting diode according to claim 28 wherein the transparent electrode comprises a layer of nickel/gold, nickel oxide/gold, nickel oxide/platinum, titanium and/or titanium/gold.

30. A light emitting diode according to claim 2 further comprising:

a barrier region between the reflector and the mounting support; and

a bonding region between the barrier region and the mounting support.

31. A light emitting diode according to claim 30 wherein the bonding region comprises gold, indium, solder and/or braze.

32. A light emitting diode according to claim 2 further comprising:

an optical element adjacent the first face, opposite the diode region.

33. A light emitting diode according to claim 2 wherein the first face of the substrate includes therein at least one groove that defines, in cross-section, the plurality of pedestals in the substrate.

34. A light emitting diode according to claim 33 wherein the pedestals are triangular pedestals.

35. A light emitting diode according to claim 33 wherein the grooves include tapered and/or curved sidewalls.

36. A light emitting diode according to claim 33 wherein the grooves include a beveled and/or curved floor.

37. A light emitting diode according to claim 35 wherein the grooves include a beveled and/or curved floor.

38. A light emitting diode according to claim 33 wherein the first and second faces of the substrate comprise square perimeters.

39. A light emitting diode according to claim 33 wherein the first face of the substrate comprises a textured surface.

40. A light emitting diode according to claim 2 wherein the first face of the substrate includes therein an array of via holes that defines, in cross-section, the plurality of pedestals in the substrate.

41. A light emitting diode according to claim 40 wherein the via holes include tapered and/or curved sidewalls.

42. A light emitting diode according to claim 40 wherein the via holes include a flat, beveled and/or curved floor.

43. A light emitting diode according to claim 41 wherein the via holes include a flat beveled and/or curved floor.

44. A light emitting diode according to claim 40 wherein the first and second faces of the substrate comprise square perimeters.

45. A light emitting diode according to claim 40 wherein the first face of the substrate comprises a textured surface.

46. A light emitting diode according to claim 40 wherein the array of via holes comprises an array of tapered and/or curved via holes.

47. A light emitting diode according to claim 2 wherein the diode region comprises a peripheral portion, at least one central portion that is enclosed by the peripheral portion and at least one emission region that is confined to within the at least one central portion and does not extend onto the peripheral portion.

48. A light emitting diode according to claim 2 further comprising:

a plurality of emission regions on the diode region, a respective one of which is confined to within a respective one of the pedestals and does not extend beyond the respective one of the pedestals.

49. A light emitting diode according to claim 33 further comprising:

a plurality of electrodes on the diode region, a respective one of which is confined to within a respective one of the pedestals and does not extend beyond the respective one of the pedestals.

50. A light emitting diode according to claim 40 further comprising:

at least one electrode on the diode region that does not overlap the via holes.

51. A light emitting diode according to claim 2, wherein the substrate comprises silicon carbide and wherein the diode region comprises gallium nitride.

4. A light emitting diode comprising:

a substrate having first and second opposing faces, that is transparent to optical radiation in a predetermined wavelength range and that is patterned to define, in cross-section, a plurality of pedestals that extend into the substrate from the first face towards the second face;

a diode region on the second face that is configured to emit light in the radiation in the predetermined wavelength range, upon application of voltage across the diode region;

a mounting support on the diode region, opposite the substrate that is transparent to optical radiation in the predetermined frequency range, the mounting support being configured to support the diode region such that the light that is emitted from the diode region into the substrate that is transparent to optical radiation in the predetermined wavelength range, is emitted from the plurality of pedestals, upon application of voltage across the diode region;

a reflector between the mounting support and the diode region, that is configured to reflect light that is emitted from the diode region back into the diode region, through the substrate that is transparent to optical radiation in the predetermined wavelength range and from the plurality of pedestals, upon application of voltage across the diode region;

a barrier region between the reflector and the mounting support; and

a bonding region between the barrier region and the mounting support.

6. A light emitting diode according to claim 4 wherein the bonding region comprises gold, indium, solder and/or braze.

52. A light emitting diode according to claim 4 further comprising:

a transparent electrode between the diode region and the reflector.

53. A light emitting diode according to claim 4 wherein the reflector comprises a layer of at least one reflective material.

54. A light emitting diode according to claim 52 wherein the transparent electrode comprises a layer of nickel/gold, nickel oxide/gold, nickel oxide/platinum, titanium and/or titanium/gold.

55. A light emitting diode according to claim 4 wherein the bonding region comprises gold, indium, solder and/or braze.

56. A light emitting diode according to claim 4 further comprising:

an optical element adjacent the first face, opposite the diode region.

57. A light emitting diode according to claim 4 wherein the first face of the substrate includes therein at least one groove that defines, in cross-section, the plurality of pedestals in the substrate.

58. A light emitting diode according to claim 57 wherein the pedestals are triangular pedestals.

59. A light emitting diode according to claim 57 wherein the grooves include tapered and/or curved sidewalls.

60. A light emitting diode according to claim 57 wherein the grooves include a beveled and/or curved floor.

61. A light emitting diode according to claim 59 wherein the grooves include a beveled and/or curved floor.

62. A light emitting diode according to claim 57 wherein the first and second faces of the substrate comprise square perimeters.

63. A light emitting diode according to claim 57 wherein the first face of the substrate comprises a textured surface.

64. A light emitting diode according to claim 4 wherein the first face of the substrate includes therein an array of via holes that defines, in cross-section, the plurality of pedestals in the substrate.

65. A light emitting diode according to claim 64 wherein the via holes include tapered and/or curved sidewalls.

66. A light emitting diode according to claim 64 wherein the via holes include a flat, beveled and/or curved foot.

67. A light emitting diode according to claim 65 wherein the via holes include a flat, beveled end/or curved floor.

68. A light emitting diode according to claim 64 wherein the first and second faces of the substrate comprise square perimeters.

69. A light emitting diode according to claim 64 wherein the first face of the substrate comprises a textured surface.

70. A light emitting diode according to claim 64 wherein the array of via holes comprises an may of tapered and/or curved via holes.

71. A light emitting diode according to claim 4 wherein the diode region comprises a peripheral portion, at least one central portion that is enclosed by the peripheral portion and at least one emission region tat is confined to within the at least one central portion and does not extend onto the peripheral portion.

72. A light emitting diode according to claim 4 further comprising:

a plurality of emission regions on the diode region, a respective one of which is confined to within a respective one of the pedestals and does not extend beyond the respective one of the pedestals.

73. A light emitting diode according to claim 57 further comprising:

a plurality of electrodes on the diode region, a respective one of which is confined to within a respective one of the pedestals and does not extend beyond the respective one of the pedestals.

74. A light emitting diode according to claim 64 further comprising:

at least one electrode on the diode region that does not overlap the via holes.

75. A light emitting diode according to claim 4, wherein the substrate comprises silicon carbide and wherein the diode region comprises gallium nitride.