Multi-chip semiconductor LED assembly

• US 6,885,035 B2
• Filed: 05/15/2001
• Issued: 04/26/2005
• Est. Priority Date: 12/22/1999
• Status: Expired due to Term

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Khare, Reena, Bhat, Jerome C., Steigerwald, Daniel A.
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Mondt, Johannes
• Application Number:
  US09/859,154
• Publication Number:
  US 20010032985A1
• Time in Patent Office: 1,442 Days
• Field of Search: 257 79- 82, 257/84, 257/85, 257/88, 257/99, 257/103
• US Class Current: 257/99
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2360/148 the light being detected by light detection means within each pixel
• CPC Class Codes: G09G 3/14 Semiconductor devices, e.g. diodes
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05005 Structure
• CPC Class Codes: H01L 2224/05541 Structure
• CPC Class Codes: H01L 2224/05567 the external layer being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/05572 the external layer extending out of an opening
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/17106 the bump connectors being bonded to at least one common bonding area
• CPC Class Codes: H01L 2224/48091 Arched
• 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 24/16 of an individual bump connector
• CPC Class Codes: H01L 24/17 of a plurality of bump connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/00014 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 2924/01029 Copper [Cu]
• 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 2924/12036 : PN diode
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 33/025 : Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/20 : with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 : with a particular shape
• CPC Class Codes: H01L 33/405 : Reflective materials
• 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
• CPC Class Codes: H01L 33/641 : characterized by the materials
• CPC Class Codes: H01L 33/647 : the elements conducting electric current to or from the semiconductor body

Abstract

A light emitting device includes several LEDs, mounted on a shared submount, and coupled to circuitry formed on the submount. The LEDs can be of the III-Nitride type. The architecture of the LEDs can be either inverted, or non-inverted. Inverted LEDs offer improved light generation. The LEDs may emit light of the same wavelength or different wavelengths. The circuitry can couple the LEDs in a combination of series and parallel, and can be switchable between various configurations. Other circuitry can include photosensitive devices for feedback and control of the intensity of the emitted light, or an oscillator, strobing the LEDs.

Claims

1. A light emitting device, comprising:

a plurality of light emitting diodes, positioned on a shared submount; and

circuitry, on said shared submount, wherein said plurality of light emitting diodes are coupled to said circuitry, said circuitry including at least one metal trace formed on the surface of or within the submount, wherein one of the plurality of light emitting diodes and a device disposed on or within the submount are electrically connected by the metal trace;

wherein the plurality of light emitting diodes are attached to the submount by at least one interconnect and wherein at least one of the light emitting diodes in the plurality comprises;

a top surface and a bottom surface opposite the top surface; and

first and second contacts electrically connected to first and second semiconductor layers of opposite polarity type, both the first and second contacts being formed on the bottom surface.

2. The light emitting device of claim 1, wherein said shared submount comprises a semiconductor material;

and

at least a portion of said circuitry is formed in said semiconductor material.

3. The light emitting device of claim 2, wherein said semiconductor material comprises silicon.

4. The light emitting device of claim 1, wherein said plurality of light emitting diodes each comprise a substrate.

5. The light emitting device of claim 1, wherein said plurality of light emitting diodes comprise inverted light emitting diodes, said inverted light emitting diodes comprising:

a substrate, having a side;

an n-doped semiconductor layer, formed overlying said substrate, having one or more first contact pads;

an active layer, formed overlying said n-doped layer; and

a p-doped semiconductor layer, formed overlying said active layer, having one or more second contact pads, wherein said one or more first contact pads and said one or more second contact pads are on said side of said substrate, and where the coupling between said contact pads and said circuitry is solderballs, ultrasonic bonds, eutectic joints, conducting epoxy or conducting paste.

6. The light emitting device of claim 5, wherein said plurality of light emitting diodes comprise inverted Ill-V light emitting diodes, wherein said n-doped semiconductor layer, said active layer, and said p-doped semiconductor layer comprise one or more Group III elements and one or more Group V elements.

7. The light emitting device of claim 1, wherein said plurality of light emitting diodes comprise:

inverted Light emitting diodes; and

non-inverted light emitting diodes, wherein said non-inverted light emitting diodes comprise;

a conducting substrate, coupled to said circuitry;

an n-doped semiconductor layer, formed overlying said substrate;

an active layer, formed overlying said n-doped layer;

a p-doped semiconductor layer, formed overlying said active layer, having a contact pad; and

a wire bond, coupling said p-doped semiconductor layer and said circuitry.

8. The light emitting device of claim 1, wherein said plurality of light emitting diodes comprise:

inverted light emitting diodes; and

non-inverted light emitting diodes, wherein said nun-inverted light emitting diodes comprise;

a conducting substrate, coupled to said circuitry;

a p-doped semiconductor layer, formed overlying said substrate;

an active layer, formed overlying said p-doped layer;

an n-doped semiconductor layer, formed overlying said active layer, having a contact pad; and

a wire bond, coupling said n-doped semiconductor layer and said circuitry.

9. The light emitting device of claim 1, wherein said circuitry couples ones of said plurality of light emitting diodes in parallel.

10. The light emitting device of claim 1, wherein said circuitry couples ones of said plurality of light emitting diodes in series.

11. The light emitting device of claim 1, wherein said circuitry couples ones of said plurality of light emitting diodes in a combination of series and parallel.

12. The light emitting device of claim 1, wherein said plurality of light emitting diodes comprise a plurality of same wavelength diodes, wherein said same wavelength diodes are capable of emitting light with the same wavelength.

13. The light emitting device of claim 1, wherein said plurality of light emitting diodes are capable of emitting light with different wavelengths.

14. The light emitting device of claim 1, comprising:

a first light emitting diode, capable of emitting red light;

a second light emitting diode, capable of emitting green light; and

a third light emitting diode, capable of emitting blue light.

15. The light emitting device of claim 1, comprising:

a first light emitting diode, capable of emitting light of a wavelength of about 420 nanometers; and

a second light emitting diode, capable of emitting light of wavelength of about 470 nanometers.

16. The light emitting device of claim 1, wherein said circuitry comprises an assembly of switches, formed in said shared submount, coupled to said plurality of light emitting diodes, capable of switching said circuitry between coupling ones of said plurality of light emitting diodes in series and parallel.

17.The light emitting device of claim 1, wherein said plurality of light emitting diodes have polarities and operating voltages, said polarities directed in a shared direction, wherein said circuitry comprises:

sub-circuitry, coupling ones of said plurality of light emitting diodes in a combination of series and parallel, having an operating voltage; and

one or more power shunting diodes, having polarities and breakdown voltages, formed on said shared submount, wherein said one or more power shunting diodes are coupled in parallel to said sub-circuitry of said ones of said plurality of light emitting diodes with polarities opposite to said shared polarity of said plurality of light emitting diodes, wherein said breakdown voltage of said one or more power shunting diodes is larger than said operating voltage of said sub-circuitry of said plurality of light emitting diodes.

17. The light emitting device of claim 1, wherein said plurality of light emitting diodes have polarities and operating voltages, said polarities directed in a shared direction, wherein said circuitry comprises:

sub-circuitry, coupling ones of said plurality of light emitting diodes in a combination of series and parallel, having an operating voltage; and

a plurality of power shunting diodes, having polarities and breakdown voltages, formed on said shared submount, wherein ones of said plurality of power shunting diodes are coupled serially, wherein said serially coupled ones of said plurality of power shunting diodes are coupled in parallel to said sub-circuitry of said ones of said plurality of light emitting diodes with polarities opposite to said shared polarity of said plurality of light emitting diodes, wherein said breakdown voltage of said serially coupled ones of said plurality of power shunting diodes is larger than said operating voltage of said sub-circuitry of said plurality of light emitting diodes.

18. The light emitting device of claim 1, wherein said plurality of light emitting diodes have operating voltages, wherein said circuitry comprises:

sub-circuitry, coupling ones of said plurality of light emitting diodes in a combination of series and parallel, said sub-circuitry having an operating voltage; and

two power shunting diodes, said power shunting diodes having polarities and breakdown voltages, formed on said shared submount, wherein said two power shunting diodes are coupled serially, with polarities opposite to each other, wherein said serially coupled two power shunting diodes are coupled in parallel to said sub-circuitry of said plurality of light omitting diodes, wherein said breakdown voltage of said serially coupled two power shunting diodes is larger than said operating voltage of said sub-circuitry of said plurality of light emitting diodes.

19. The light emitting device of claim 1, wherein said plurality of light emitting diodes have operating voltages;

wherein said circuitry comprises;

sub-circuitry, coupling ones of said plurality of light emitting diodes in a combination of series and parallel, said sub-circuitry having an operating voltage; and

a plurality of power shunting diodes, forming a plurality of pairs, said power shunting diodes having polarities and breakdown voltages, formed on said shared submount, wherein said power shunting diodes are formed with polarities opposite to each other within said pairs individually, wherein ones of said pairs of said power shunting diodes are coupled serially, wherein said serially coupled ones of said plurality of pairs of power shunting diodes are coupled in parallel to said sub-circuitry of said plurality of light emitting diodes, wherein said breakdown voltage of said serially coupled plurality of pairs of power shunting diodes is larger than said operating voltage of said sub-circuitry of said plurality of light emitting diodes.

20. The light emitting device of claim 1, wherein said plurality of light emitting diodes have polarities and operating voltages, and wherein said circuitry further comprises:

one or more power shunting diodes, having a polarity and a breakdown voltage, formed on said shared submount, wherein at least one of said one or more power shunting diodes is coupled in parallel to at least one of said plurality of light emitting diodes with a polarity opposite to the polarity of said at least one of said plurality of light emitting diodes, wherein said breakdown voltage of said at least one of said one or more power shunting diodes is larger than said operating voltage of said at least one of said plurality of light emitting diodes.

21. The light emitting device of claim 1, wherein said circuitry comprises a plurality of power shunting diodes, forming one or more pairs, said power shunting diodes having polarities and breakdown voltages, formed on said shared submount, wherein said power shunting diodes are formed with polarities opposite to each other within said one or more pairs individually, wherein at least one of said one or more pairs of power shunting diodes are coupled in parallel to at least one of said plurality of light emitting diodes, wherein said breakdown voltage of said at least one of said one or more pairs of power shunting diodes is larger than said operating voltage of said at least one of said plurality of light emitting diodes.

22. The light emitting device of claim 1, wherein said circuitry comprises a logic circuit, formed in said shared submount.

23. The light emitting device of claim 1, wherein said circuitry comprises:

at least one light sensitive device, formed in or on said shared submount for receiving a portion of light, emitted by said plurality of light emitting diodes; and

a control circuit, formed in said shared submount, coupled to said at least one light sensitive device and to said plurality of light emitting diodes for controlling current to said plurality of light emitting diodes based on light received by said at least one light sensitive device.

28. The light emitting device of claim 1, wherein said circuitry comprises an oscillator circuit, formed in said shared substrate, coupled to said plurality of light emitting diodes.

29. The light emitting device of claim 1 wherein the submount is external to the plurality of light emitting diodes.

30. The light emitting device of claim 1 wherein the interconnect is solder.

31. The light emitting device of claim 4 wherein:

said plurality of light emitting diodes each comprise a plurality of semiconductor layers including a light-emitting layer;

the semiconductor layers are epitaxially grown on the substrate; and

the submount and the substrate do not touch.

32. The light emitting device of claim 1 wherein the interconnect comprises gold.

33. The light emitting device of claim 1 wherein the device is another of the plurality of light emitting diodes.

34. The light emitting device of claim 1 wherein the submount comprises AlN.

35. The light emitting device of claim 1 wherein the submount comprises BeO.

24. The light emitting device of claim 24, wherein said at least one light sensitive device comprises a light sensitive diode.

25. The light emitting device of claim 24, wherein said at least one light sensitive device comprises a light sensitive transistor.

26. The light emitting device of claim 24, wherein said plurality of light emitting diodes have sides, wherein said at least one light sensitive device is formed in or on said shared submount at least partially under said plurality light emitting diodes, for receiving a portion of light emitted from said side of said plurality of light emitting diodes.

27. The light emitting device of claim 24, wherein at least one of said plurality of light emitting diodes is positioned above at least one of said light sensitive devices, wherein said at least one light sensitive device senses only the light emitted by said at least one of said plurality of light emitting diodes positioned above.