LIGHT EMITTING DIODE WITH BONDED SEMICONDUCTOR WAVELENGTH CONVERTER

• US 20100283074A1
• Filed: 09/09/2008
• Published: 11/11/2010
• Est. Priority Date: 10/08/2007
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Smith, Terry L., Haase, Michael A., Leatherdale, Catherine A., Kelley, Tommie W.
• Application Number:
  US12/681,878
• Publication Number:
  US 20100283074A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 25/0756 Stacked arrangements of devices
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/02 characterised by the semiconductor bodies
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/502 Wavelength conversion materials

Abstract

A light emitting diode (LED) has various LED layers provided on a substrate. A multilayer semiconductor wavelength converter, capable of converting the wavelength of light generated in the LED to light at a longer wavelength, is attached to the upper surface of the LED by a bonding layer. One or more textured surfaces within the LED are used to enhance the efficiency at which light is transported from the LED to the wavelength converter. In some embodiments, one or more surfaces of the wavelength converter is provided with a textured surface to enhance the extraction efficiency of the long wavelength light generated within the converter.

Claims

1. A semiconductor stack capable of being diced into multiple light emitting diodes (LEDs) comprising:

a light emitting diode (LED) wafer comprising a first stack of LED semiconductor layers disposed on an LED substrate, at least part of the LED wafer comprising a first textured surface;

a multilayer semiconductor wavelength converter configured to be effective at converting the wavelength of light generated in the LED layers; and

a bonding layer attaching the LED wafer to the wavelength converter.

2. A wafer as recited in claim 1, wherein the first textured surface is on a surface of the LED wafer facing away from the LED substrate.

3. A wafer as recited in claim 1, wherein the bonding layer is a polymer layer.

4. A stack as recited in claim 1, wherein at least a part of a first side of the wavelength converter comprises a second textured surface.

5. A stack as recited in claim 4, wherein at least a part of a second side of the wavelength converter comprises a textured surface.

6. A stack as recited in claim 1, wherein the LED substrate comprises a first side facing away from the stack of LED semiconductor layers, at least part of the first side of the LED substrate comprising a third textured surface.

7. A stack as recited in claim 1, further comprising a reflective bonding layer bonding between the LED substrate and the LED semiconductor layers.

8. A stack as recited in claim 7, wherein the reflective bonding layer is a metal layer.

9. A stack as recited in claim 6, further comprising a fourth textured surface between the LED semiconductor layers and the LED substrate.

10. A stack as recited in claim 1, wherein the semiconductor wavelength converter comprises II-VI semiconductor material.

11. A stack as recited in claim 1, wherein the bonding layer comprises inorganic particles disposed within a bonding material.

12. A method of making wavelength converted, light emitting diodes, comprising:

providing a light emitting diode (LED) wafer comprising a set of LED semiconductor layers disposed on a substrate, the LED wafer having a textured surface;

providing a multilayer semiconductor wavelength converter wafer configured to be effective at converting wavelength of light generated within the LED layers;

bonding the converter wafer to the LED wafer to produce an LED/converter wafer using a bonding layer disposed between the LED wafer and the converter wafer; and

separating individual converted LED dies from the LED/converter wafer.

13. A method as recited in claim 12, wherein bonding the converter wafer to the LED wafer comprises bonding the LED wafer to the textured surface of the LED wafer.

14. A method as recited in claim 12, wherein bonding the converter wafer to the textured surface comprises bonding the converter wafer to the textured surface using a polymer material.

15. A method as recited in claim 12, further comprising etching through the converter wafer to expose electrical connection areas of the first side of the LED wafer.

16. A method as recited in claim 12, wherein separating individual converted LED dies comprises dicing the LED/converter wafer using a saw.

17. A method as recited in claim 12, further comprising removing a converter substrate from the converter wafer after bonding the converter wafer to the textured surface.

18. A method as recited in claim 12, wherein bonding the converter wafer to the textured surface comprises bonding a first side of the converter wafer to the textured surface and further comprising texturing a first side of the converter wafer.

19. A method as recited in claim 18, further comprising texturing a second side of the converter wafer.

20. A method as recited in claim 12, further comprising bonding the LED semiconductor layers to the LED substrate using a reflective bonding layer.

21. A method as recited in claim 12, wherein the LED substrate is transparent and further comprising providing a textured surface on a side of the LED substrate facing away from the wavelength converter wafer.

22. A method as recited in claim 20, further comprising providing a textured surface on a side of the LED semiconductor layers facing the second LED substrate.

23. A method as recited in claim 12, further comprising providing light blocking features in the LED/converter wafer and wherein separating the individual LED dies comprises separating the LED/converter wafer at the light blocking features.

24. A method as recited in claim 12, wherein providing the wavelength converter wafer comprises providing a multilayer wavelength converter wafer comprising II-VI semiconductor material.

25. A wavelength converted light emitting diode (LED), comprising:

an LED comprising LED semiconductor layers on an LED substrate, the LED comprising a first surface on a side of the LED facing away from the LED substrate; and

a multilayered semiconductor wavelength converter attached to the first surface of the LED by a bonding layer, the wavelength converter having a first side facing away from the LED and a second side facing the LED, at least part of one of the first side and the second side of the wavelength converter comprising a first textured surface.

26. A device as recited in claim 25, wherein at least a part of the other of the first side and the second side of the wavelength converter comprises a second textured surface.

27. A device as recited in claim 25, wherein at least a part of the first surface of the LED comprises a third textured surface, the wavelength converter being attached to the third textured surface.

28. A device as recited in claim 25, wherein the LED substrate comprises a first side facing away from the wavelength converter, at least part of the first side of the LED substrate comprising a fourth textured surface.

29. A device as recited in claim 25, further comprising a reflective bonding layer attaching the LED substrate to the LED semiconductor layers.

30. A device as recited in claim 25, wherein the LED semiconductor layers have a first side facing the LED substrate, at least part of the first side of the LED semiconductor layers comprising a fifth textured surface.

31. A device as recited in claim 25, further comprising at least one light blocking feature provided at an edge of the LED semiconductor layers to reduce leakage of light generated within the LED semiconductor layers.

32. A device as recited in claim 25, wherein the wavelength converter stack comprises II-VI semiconductor material.

33. A device as recited in claim 25, further comprising a bonding layer disposed between the LED and the wavelength converter.

34. A device as recited in claim 33, wherein the bonding layer comprises inorganic particles disposed within a bonding material.

35. A wavelength converted light emitting diode (LED), comprising:

an LED comprising a stack of LED semiconductor layers on an LED substrate, at least part of a first side of the stack of LED semiconductor layers facing the LED substrate comprising a first textured surface; and

a multilayer semiconductor wavelength converter attached by a bonding layer to a side of the LED facing away from the LED substrate.

36. A device as recited in claim 35, wherein at least a part of a second side of the LED facing away from the LED substrate comprises a second textured surface, the second textured surface being attached to the wavelength converter.

37. A device as recited in claim 35, wherein the wavelength converter comprises a first facing away from the LED and a second side facing the LED, at least part of one of the first and second sides of the wavelength converter comprising a third textured surface.

38. A device as recited in claim 37, wherein at least part of the other of the first and second sides of the wavelength converter comprises a fourth textured surface.

39. A device as recited in claim 35, further comprising at least one light blocking feature provided at an edge of the LED semiconductor layers to reduce leakage of light generated within the LED semiconductor layers.

40. A device as recited in claim 35, wherein the bonding layer comprises a polymer bonding layer.

41. A device as recited in claim 40, wherein the bonding layer comprises inorganic particles disposed within a bonding material.

42. A device as recited in claim 35, wherein the wavelength converter comprises II-VI semiconductor material.

43. A wavelength converted light emitting diode (LED) device, comprising:

an LED comprising a stack of LED semiconductor layers on an LED substrate, at least part of a first side of the LED substrate facing away from the stack of LED semiconductor layers comprising a first textured surface; and

a multilayer semiconductor wavelength converter attached by a bonding layer to a side of the LED facing away from the LED substrate.

44. A device as recited in claim 43, wherein at least a part of a first surface of the stack of LED semiconductor layers facing away from the LED substrate comprises a second textured surface, the second textured surface being bonded to the wavelength converter.

45. A device as recited in claim 43, wherein the wavelength converter comprises a first side facing away from the LED and a second side facing the LED, at least part of one of the first side and the second side of the wavelength converter comprising a third textured surface.

46. A device as recited in claim 45, wherein at least a part of the other of the first side and the second side of the wavelength converter comprises a fourth textured surface.

47. A device as recited in claim 43, wherein the stack of LED semiconductor layers has a first side facing the LED substrate, at least part of the first side of the stack of LED semiconductor layers comprising a fifth textured surface.

48. A device as recited in claim 43, wherein the LED substrate is substantially transparent to light generated within the LED semiconductor layers.

49. A device as recited in claim 43, further comprising at least one light blocking feature provided at an edge of the stack of LED semiconductor layers to reduce leakage of light generated within the LED semiconductor layers.

50. A device as recited in claim 43, further comprising a bonding layer attaching the wavelength converter to the LED.

51. A device as recited in claim 50, wherein the bonding layer comprises a polymer bonding layer.

52. A device as recited in claim 50, wherein the bonding layer comprises inorganic particles disposed within a bonding material.

53. A device as recited in claim 43, wherein the wavelength converter comprises II-VI semiconductor material.

54. A device as recited in claim 43, further comprising a reflective coating on the textured surface of the first side of the LED substrate.

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

an LED comprising a stack of LED semiconductor layers on an LED substrate, at least part of an upper side of the stack of LED semiconductor layers stack facing away from the LED substrate comprising a textured surface;

a multilayer wavelength converter formed of a II-VI semiconductor material and attached to the LED semiconductor layer stack; and

a light blocking feature provided at the edge of LED semiconductor layers to reduce edge-leakage of light generated within the LED semiconductor layers.

56. A device as recited in claim 55, wherein the wavelength converter has a first side facing away from the stack of LED semiconductor layers and a second side facing the stack of LED semiconductor layers, at least part of one of the first side and the second side of the wavelength converter comprising a textured surface.

57. A device as recited in claim 56, wherein at least a part of the other of the first side and the second side of the wavelength converter comprises a textured surface.

58. A device as recited in claim 55, wherein the LED substrate comprises a first side facing away from the wavelength converter, at least part of the first side of the LED substrate comprising a textured surface.

59. A device as recited in claim 55, further comprising a reflective bonding layer attaching the stack of LED semiconductor layers to the LED substrate.

60. A device as recited in claim 55, wherein the LED substrate is substantially transparent to light generated within the LED semiconductor layers, the LED substrate having a first side facing away from the stack of LED semiconductor layers, at least part of the first side of the LED substrate comprising a textured surface.

61. A device as recited in claim 60, wherein the stack of LED semiconductor layers comprises a first side facing the LED substrate, at least part of the first side of the stack of LED semiconductor layers comprising a textured surface.

62. A device as recited in claim 55, further comprising a bonding layer attaching the wavelength converter to the LED.

63. A wavelength converted light emitting diode (LED) device, comprising:

an LED comprising a stack of LED semiconductor layers on an LED substrate, the LED comprising a first textured surface; and

a multilayer semiconductor wavelength converter attached by a bonding layer to the LED.

64. A device as recited in claim 63, wherein the first textured surface is on an output surface of the LED, light passing from the LED via the output surface to the wavelength converter.

65. A device as recited in claim 63, wherein the first textured surface is on the LED substrate.

66. A device as recited in claim 63, wherein the first textured surface is between the LED semiconductor layers and the LED substrate.

67. A device as recited in claim 63, wherein wavelength converter is attached to the first textured surface by the bonding layer.

68. A device as recited in claim 63, wherein the wavelength converter comprises a second textured surface.

69. A wavelength converter device for a light emitting diode (LED), comprising:

a multilayer semiconductor wavelength converter element;

a bonding layer disposed on one side of the wavelength converter element; and

a removable protective layer over the bonding layer.

70. A device as recited in claim 69, wherein the bonding layer is an adhesive bonding layer.

71. A device as recited in claim 69, wherein the bonding layer is a polymeric adhesive bonding layer.

72. A device as recited in claim 69, wherein the wavelength converter element comprises a textured surface.