FAULT TOLERANT LIGHT EMITTERS, SYSTEMS INCORPORATING FAULT TOLERANT LIGHT EMITTERS AND METHODS OF FABRICATING FAULT TOLERANT LIGHT EMITTERS

• US 20080179602A1
• Filed: 01/22/2008
• Published: 07/31/2008
• Est. Priority Date: 01/22/2007
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: LED Lighting Fixtures, Inc. (Wolfspeed, Inc.)
• Inventors: Van De Ven, Antony Paul, NEGLEY, Gerald H.
• Granted Patent: US 9,391,118 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 21/2654 in AIIIBV compounds
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• 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 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

There is provided a light emitter comprising light emitting devices (for example, light emitting diodes) which are electrically interconnected to provide an array of at least two serially connected subsets of parallel connected light emitting devices, each subset comprising at least three light emitting devices. In some embodiments, the light emitting devices are from a contiguous region of a wafer. There is also provided a light emitter, comprising light emitting devices, means for mechanically interconnecting the light emitting devices and means for electrically interconnecting the light emitting devices to provide serially connected subsets interconnected in parallel, each subset comprising at least three light emitting devices. Also, methods of fabricating light emitters.

Claims

1. A light emitter, comprising:

a plurality of light emitting devices mechanically interconnected by a common substrate on which the light emitting devices are formed;

wherein the light emitting devices are electrically interconnected on the common substrate to provide an array of at least two serially connected subsets of parallel connected light emitting devices, each subset comprising at least three light emitting devices.

2. The light emitter of claim 1, wherein the forward voltage of the light emitter is at least 325 volts.

3. The light emitter of claim 1, wherein the forward voltage of the light emitter is at least 395 volts.

4. The light emitter of claim 1, wherein the light emitting devices comprise light emitting diodes (LEDs).

5. The light emitter of claim 4, wherein the LEDs are isolated from one another by an insulating region.

6. The light emitter of claim 4, wherein the LEDs are isolated from one another by a trench.

7. The light emitter of claim 4, wherein the LEDs are lateral devices.

8. The light emitter of claim 4, wherein the LEDs are vertical devices.

9. The light emitter of claim 1, wherein the light emitter further comprises at least one fuse link electrically connected in series with at least one of the light emitting devices.

10. The light emitter of claim 1, wherein the light emitter further comprises at least one means for opening an electrically conductive connection in series with at least one of the light emitting devices.

11. A light emitter comprising:

a plurality of light emitting devices from a contiguous region of a wafer of light emitting devices, the plurality of light emitting devices being electrically connected on a substrate as a plurality of serially connected subsets of parallel connected light emitting devices, each subset comprising at least three light emitting devices.

12. The light emitter of claim 11, wherein the plurality of serially connected subsets comprises at least forty subsets.

13. The light emitter of claim 11, wherein the plurality of serially connected subsets comprises at least one hundred subsets.

14. The light emitter of claim 11, wherein the plurality of light emitting devices are mechanically connected by a common substrate of the wafer.

15. The light emitter of claim 14, wherein the light emitting devices are defined by at least one insulating region that defines a periphery of each of the individual light emitting devices.

16. The light emitter of claim 14, wherein the light emitting devices are defined by at least one trench that defines a periphery of each of the individual light emitting devices.

17. The light emitter of claim 11, further comprising a mechanical substrate on which the light emitting devices are mounted to provide mechanical support for the light emitting devices.

18. The light emitter of claim 11, wherein the light emitting devices comprise lateral devices.

19. The light emitter of claim 11, wherein the light emitting devices comprise vertical devices.

20. The light emitter of claim 11, wherein the light emitter further comprises at least one fuse link electrically connected in series with at least one of the light emitting devices.

21. The light emitter of claim 11, wherein the light emitter further comprises at least one means for opening an electrically conductive connection in series with at least one of the light emitting devices.

22. A light emitter, comprising:

a plurality of light emitting devices;

means for mechanically interconnecting the plurality of light emitting devices; and

means for electrically interconnecting the plurality of light emitting devices to provide serially connected subsets of light emitting devices that are electrically interconnected in parallel, each subset comprising at least three light emitting devices.

23. The light emitter of claim 22, further comprising means for healing a short-circuit failure of one of the plurality of light emitting devices.

24. The light emitter of claim 22, wherein:

the light emitter further comprises a boost power supply having an output voltage that is greater than a corresponding input voltage; and

the serially connected subsets of light emitting devices are electrically coupled to the output voltage of the boost power supply.

25. The light emitter of claim 24, wherein the boost power supply is configured to be coupled to an AC power source to provide the input voltage.

26. A method of fabricating a light emitter, comprising:

forming a plurality of light emitting devices on a substrate; and

electrically connecting the light emitting devices on the substrate to provide an array of at least two serially connected subsets of parallel connected light emitting devices, each subset comprising at least three light emitting devices.

27. The method of claim 26, wherein the array provides a forward voltage for the light emitter of at least 18 volts.

28. The method of claim 26, wherein the method further comprises testing at least one of the light emitting devices.

29. The method of claim 26, wherein the method further comprises testing at least one of the light emitting devices and electrically disconnecting one of the light emitting devices from the light emitting device.

30. The method of claim 29, wherein the step of electrically disconnecting one of the light emitting devices is carried out by etching an anode contact or a cathode contact of one of the light emitting devices.

31. The method of claim 29, wherein the step of electrically disconnecting one of the light emitting devices is carried out by applying insulating material on an anode contact or a cathode contact of one of the light emitting devices.

32. A method of fabricating a light emitter, comprising:

forming a plurality of light emitting device layers on a substrate;

defining individual light emitting devices in regions of the light emitting device layers; and

electrically connecting the individual light emitting devices on the substrate to provide serially connected subsets of the light emitting devices, wherein each of the subsets comprises at least three light emitting devices electrically connected in parallel.

33. The method of claim 32, wherein defining individual light emitting devices comprises implanting ions about the peripheries of the light emitting devices to provide at least one insulating or semi-insulating region that defines the peripheries of the individual light emitting devices.

34. The method of claim 33, wherein each of the light emitting devices comprises a lateral light emitting device having a first surface on which a first ohmic contact is provided on a first contact layer of the respective light emitting device and a second, buried contact layer, and wherein the step of electrically connecting individual light emitting devices comprises:

for each light emitting device, forming a conductive region that extends from the first surface through the insulating or semi-insulating region of the light emitting device to electrically connect to the buried contact layer;

for each light emitting device, forming an ohmic contact on the conductive region to provide a second ohmic contact electrically connected to the buried contact layer; and

forming an electrical interconnection pattern on the respective first surfaces of the light emitting devices to selectively interconnect first ohmic contacts and second ohmic contacts to provide the serially connected subsets of light emitting devices.

35. The method of claim 34, wherein forming a conductive region comprises forming a highly doped region of semiconductor material of the same conductivity type as the buried contact layer.

36. The method of claim 34, wherein forming a conductive region comprises, for each light emitting device, forming a conductive via extending from the first surface to the buried contact layer.

37. The method of claim 33, wherein each of the light emitting devices comprises a vertical light emitting diode having respective ohmic contacts on opposite faces of the light emitting device, and wherein electrically connecting individual light emitting devices comprises:

forming interconnection patterns on the opposite faces of the light emitting devices to electrically connect respective ohmic contacts of the light emitting devices into the subsets of light emitting devices, the interconnection patterns extending onto the electrically insulating or semi-insulating regions; and

forming conductive vias through the electrically insulating or semi-insulating regions to selectively electrically connect respective interconnection patterns so as to serially connect the subsets of light emitting devices.

38. The method of claim 32, further comprising forming light extraction features in the substrate.

39. The method of claim 32, wherein defining individual light emitting devices comprises forming at least one trench about the peripheries of the light emitting devices, wherein the at least one trench defines the peripheries of the individual light emitting devices.

40. The method of claim 39, wherein each light emitting device includes a first ohmic contact and the at least one trench extends to respective contact layers of each of the light emitting devices, the method further comprising:

forming a second ohmic contact on the contact layer of each of the light emitting devices;

filling the at least one trench with an insulator material;

forming a plurality of conductive vias through the insulator material, each conductive via contacting the first ohmic contact of one of the light emitting devices; and

wherein electrically connecting the individual light emitting devices comprises forming interconnection patterns that electrically connect respective first contacts of a first subset of the light emitting devices to respective conductive vias associated with second contacts of a second subset of the light emitting devices.

41. The method of claim 32, wherein the method further comprises testing at least one of the light emitting devices.

42. The method of claim 32, wherein the method further comprises testing at least one of the light emitting devices and electrically disconnecting one of the light emitting devices from the light emitting device.

43. The method of claim 42, wherein the step of electrically disconnecting one of the light emitting devices is carried out by etching an anode contact or a cathode contact of one of the light emitting devices.

44. The method of claim 42, wherein the step of electrically disconnecting one of the light emitting devices is carried out by applying insulating material on an anode contact or a cathode contact of one of the light emitting devices.

45. A light emitter, comprising:

a plurality of light emitting devices formed on a common substrate, each of the light emitting devices comprising means for generating light,

means for electrically connecting at least first, second and third of the light emitting devices in parallel as a first subset;

means for electrically connecting at least fourth, fifth and sixth of the light emitting devices in parallel as a second subset;

means for electrically connecting the first subset and the second subset in series.

46. A light emitter as recited in claim 45, wherein:

the first light emitting device comprises a first n-type region and a first p-type region;

the second light emitting device comprises a second n-type region and a second p-type region;

the third light emitting device comprises a third n-type region and a third p-type region;

the fourth light emitting device comprises a fourth n-type region and a fourth p-type region;

the fifth light emitting device comprises a fifth n-type region and a fifth p-type region;

the sixth light emitting device comprises a sixth n-type region and a sixth p-type region;

the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region and the sixth n-type region are each regions of a single monolithic n-type layer;

the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region and the sixth p-type region are each regions of a single monolithic p-type layer;

the light emitter comprises means for isolating each of the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region and the sixth n-type region from each other; and

the light emitter comprises means for isolating each of the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region and the sixth p-type region from each other.

47. The light emitter of claim 45, wherein the light emitter further comprises at least one fuse link electrically connected in series with at least one of the light emitting devices.

48. The light emitter of claim 45, wherein the light emitter further comprises at least one means for opening an electrically conductive connection in series with at least one of the light emitting devices.

49. A light emitter, comprising:

a substrate; and

at least first, second, third, fourth, fifth and sixth solid state light emitting devices,

the first solid state light emitting device comprising a first n-type region and a first p-type region,

the second solid state light emitting device comprising a second n-type region and a second p-type region,

the third solid state light emitting device comprising a third n-type region and a third p-type region,

the fourth solid state light emitting device comprising a fourth n-type region and a fourth p-type region,

the fifth solid state light emitting device comprising a fifth n-type region and a fifth p-type region,

the sixth solid state light emitting device comprising a sixth n-type region and a sixth p-type region,

the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region and the sixth n-type region each being isolated regions of a single monolithic n-type layer,

the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region and the sixth p-type region each being isolated regions of a single monolithic p-type layer,

an anode end of the first solid state light emitting device being electrically connected on the substrate to an anode end of the second solid state light emitting device and an anode end of the third solid state light emitting device;

a cathode end of the first solid state light emitting device being electrically connected on the substrate to a cathode end of the second solid state light emitting device and a cathode end of the third solid state light emitting device;

the cathode end of the first solid state light emitting device being electrically connected on the substrate to an anode end of the fourth solid state light emitting device;

the anode end of the fourth solid state light emitting device being electrically connected on the substrate to an anode end of the fifth solid state light emitting device and an anode end of the sixth solid state light emitting device; and

a cathode end of the fourth solid state light emitting device being electrically connected on the substrate to a cathode end of the fifth solid state light emitting device and a cathode end of the sixth solid state light emitting device.

50. The light emitter of claim 49, wherein the light emitter further comprises at least one fuse link electrically connected in series with at least one of the light emitting devices.

51. The light emitter of claim 49, wherein the light emitter further comprises at least one means for opening an electrically conductive connection in series with at least one of the light emitting devices.

52. A light emitter, comprising:

at least first, second, third, fourth, fifth and sixth solid state light emitting devices;

the first solid state light emitting device comprising a first n-type region and a first p-type region,

the second solid state light emitting device comprising a second n-type region and a second p-type region,

the third solid state light emitting device comprising a third n-type region and a third p-type region,

the fourth solid state light emitting device comprising a fourth n-type region and a fourth p-type region,

the fifth solid state light emitting device comprising a fifth n-type region and a fifth p-type region,

the sixth solid state light emitting device comprising a sixth n-type region and a sixth p-type region,

the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region and the sixth n-type region each being isolated regions of a single monolithic n-type layer,

the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region and the sixth p-type region each being isolated regions of a single monolithic p-type layer,

a first anode electrically connected to the first p-type region;

a first cathode electrically connected to the first n-type region;

a second anode electrically connected to the second p-type region;

a second cathode electrically connected to the second n-type region;

a third anode electrically connected to the third p-type region;

a third cathode electrically connected to the third n-type region;

a fourth anode electrically connected to the fourth p-type region;

a fourth cathode electrically connected to the fourth n-type region;

a fifth anode electrically connected to the fifth p-type region;

a fifth cathode electrically connected to the fifth n-type region;

a sixth anode electrically connected to the sixth p-type region;

a sixth cathode electrically connected to the sixth n-type region;

a first interconnect electrically connected to the first anode, the second anode and the third anode;

a second interconnect electrically connected to the first cathode, the second cathode and the third cathode; and

a third interconnect electrically connected to the fourth cathode, the fifth cathode and the sixth cathode.

53. A light emitter as recited in claim 52, wherein said light emitter is suitable for operation with an AC power source.

54. The light emitter of claim 52, wherein the first interconnect, the second interconnect and the third interconnect are all positioned to a first side of the p-type layer.

55. The light emitter of claim 52, wherein the light emitter further comprises at least one fuse link electrically connected in series with at least one of the light emitting devices and/or at least one means for opening an electrically conductive connection in series with at least one of the light emitting devices.

56. A light emitter, comprising:

at least first, second, third, fourth, fifth and sixth solid state light emitting devices;

the first solid state light emitting device comprising a first n-type region and a first p-type region,

the second solid state light emitting device comprising a second n-type region and a second p-type region,

the third solid state light emitting device comprising a third n-type region and a third p-type region,

the fourth solid state light emitting device comprising a fourth n-type region and a fourth p-type region,

the fifth solid state light emitting device comprising a fifth n-type region and a fifth p-type region,

the sixth solid state light emitting device comprising a sixth n-type region and a sixth p-type region,

the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region and the sixth n-type region each being isolated regions of a single monolithic n-type layer,

the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region and the sixth p-type region each being isolated regions of a single monolithic p-type layer,

a first p-type contact electrically connected to the first p-type region,

a first n-type contact electrically connected to the first n-type region,

a second p-type contact electrically connected to the second p-type region,

a second n-type contact electrically connected to the second n-type region,

a third p-type contact electrically connected to the third p-type region,

a third n-type contact electrically connected to the third n-type region,

a fourth p-type contact electrically connected to the fourth p-type region,

a fourth n-type contact electrically connected to the fourth n-type region,

a fifth p-type contact electrically connected to the fifth p-type region,

a fifth n-type contact electrically connected to the fifth n-type region,

a sixth p-type contact electrically connected to the sixth p-type region,

a sixth n-type contact electrically connected to the sixth n-type region,

a first interconnect electrically connected to the first p-type contact, the second p-type contact and the third p-type contact,

a second interconnect electrically connected to the first n-type contact, the second n-type contact and the third n-type contact,

a third interconnect electrically connected to the fourth p-type contact, the fifth p-type contact and the sixth p-type contact, and

a conductive via electrically connected to the second interconnect and the third interconnect, the conductive via extending through the p-type layer.

57. A light emitter as recited in claim 56, wherein said light emitter is suitable for operation with an AC power source.

58. The light emitter of claim 56, wherein the light emitter further comprises at least one fuse link electrically connected in series with at least one of the light emitting devices.

59. The light emitter of claim 56, wherein the light emitter further comprises at least one means for opening an electrically conductive connection in series with at least one of the light emitting devices.

60. A light emitter, comprising:

at least a first array of solid state light emitting devices and a second array of solid state light emitting devices, the first array of solid state light emitting devices comprising at least first, second, third, fourth, fifth and sixth solid state light emitting devices,

the first solid state light emitting device comprising a first n-type region and a first p-type region,

the second solid state light emitting device comprising a second n-type region and a second p-type region,

the third solid state light emitting device comprising a third n-type region and a third p-type region,

the fourth solid state light emitting device comprising a fourth n-type region and a fourth p-type region,

the fifth solid state light emitting device comprising a fifth n-type region and a fifth p-type region,

the sixth solid state light emitting device comprising a sixth n-type region and a sixth p-type region,

the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region and the sixth n-type region each being isolated regions of a single monolithic n-type layer,

the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region and the sixth p-type region each being isolated regions of a single monolithic p-type layer,

a cathode end of the first solid state light emitting device being electrically connected to a cathode end of the second solid state light emitting device and a cathode end of the third solid state light emitting device,

a cathode end of the fourth solid state light emitting device being electrically connected to a cathode end of the fifth solid state light emitting device and a cathode end of the sixth solid state light emitting device,

the cathode end of the first solid state light emitting device being electrically connected to an anode end of the fourth solid state light emitting device, the anode end of the first solid state light emitting device being electrically connected to the anode end of the second solid state light emitting device and the anode end of the third solid state light emitting device, and

the first array and the second array being electrically arranged in an anti-parallel relationship.

61. A light emitter as recited in claim 60, wherein said second array comprises at least seventh, eighth, ninth, tenth, eleventh and twelfth solid state light emitting devices,

the seventh solid state light emitting device comprising a seventh n-type region and a seventh p-type region,

the eighth solid state light emitting device comprising an eighth n-type region and an eighth p-type region,

the ninth solid state light emitting device comprising a ninth n-type region and a ninth p-type region,

the tenth solid state light emitting device comprising a tenth n-type region and a tenth p-type region,

the eleventh solid state light emitting device comprising an eleventh n-type region and an eleventh p-type region,

the twelfth solid state light emitting device comprising a twelfth n-type region and a twelfth p-type region,

the seventh n-type region, the eighth n-type region, the ninth n-type region, the tenth n-type region, the eleventh n-type region and the twelfth n-type region each being isolated regions of a single monolithic n-type layer,

the seventh p-type region, the eighth p-type region, the ninth p-type region, the tenth p-type region, the eleventh p-type region and the twelfth p-type region each being isolated regions of a single monolithic p-type layer,

a cathode end of the seventh solid state light emitting device being electrically connected to a cathode end of the eighth solid state light emitting device and a cathode end of the ninth solid state light emitting device,

a cathode end of the tenth solid state light emitting device being electrically connected to a cathode end of the eleventh solid state light emitting device and a cathode end of the twelfth solid state light emitting device,

the cathode end of the seventh solid state light emitting device being electrically connected to an anode end of the tenth solid state light emitting device, and

the anode end of the seventh solid state light emitting device being electrically connected to the anode end of the eighth solid state light emitting device and the anode end of the ninth solid state light emitting device.

62. A light emitter as recited in claim 60, wherein at least the solid state light emitting devices in the first array and the solid state light emitting devices in the second array have a common substrate.

63. A light emitter as recited in claim 60, wherein at least the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region, the sixth n-type region and the n-type regions of the solid state light emitting devices in the second array are all part of the same integral n-type element.

64. A light emitter as recited in claim 60, wherein at least the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region, the sixth p-type region and the p-type regions of the solid state light emitting devices in the second array are all part of the same integral p-type element.

65. A circuit for a light emitter, the circuit comprising:

a rectifying bridge;

at least first, second, third, fourth, fifth and sixth solid state light emitting devices,

the first solid state light emitting device comprising a first n-type region and a first p-type region,

the second solid state light emitting device comprising a second n-type region and a second p-type region,

the third solid state light emitting device comprising a third n-type region and a third p-type region,

the fourth solid state light emitting device comprising a fourth n-type region and a fourth p-type region,

the fifth solid state light emitting device comprising a fifth n-type region and a fifth p-type region,

the sixth solid state light emitting device comprising a sixth n-type region and a sixth p-type region,

the first n-type region, the second n-type region, the third n-type region, the fourth n-type region, the fifth n-type region and the sixth n-type region each being isolated regions of a single monolithic n-type layer,

the first p-type region, the second p-type region, the third p-type region, the fourth p-type region, the fifth p-type region and the sixth p-type region each being isolated regions of a single monolithic p-type layer,

a cathode end of the first solid state light emitting device being electrically connected to a cathode end of the second solid state light emitting device and a cathode end of the third solid state light emitting device;

a cathode end of the fourth solid state light emitting device being electrically connected to a cathode end of the fifth solid state light emitting device and a cathode end of the sixth solid state light emitting device;

the cathode end of the first solid state light emitting device being electrically connected to an anode end of the fourth solid state light emitting device;

the anode end of the first solid state light emitting device being electrically connected to the anode end of the second solid state light emitting device and the anode end of the third solid state light emitting device.

66. A circuit as recited in claim 65, wherein the rectifying bridge comprises at least one solid state light emitting device.