Reflective Layer for Light-Emitting Diodes

• US 20100038655A1
• Filed: 11/13/2008
• Published: 02/18/2010
• Est. Priority Date: 08/18/2008
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: TSMC Solid State Lighting Ltd. (Epistar Corporation)
• Inventors: Yu, Chen-Hua, Yu, Chia-Lin, Chen, Ding-Yuan, Chiou, Wen-Chih
• Granted Patent: US 8,716,723 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• 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 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/42 Transparent 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

A system and method for manufacturing a light-generating device is described. A preferred embodiment comprises a plurality of LEDs formed on a substrate. Each LED preferably has spacers along the sidewalls of the LED, and a reflective surface is formed on the substrate between the LEDs. The reflective surface is preferably located lower than the active layer of the individual LEDs.

Claims

1. A light-generating device comprising:

a substrate;

a first light-emitting diode on the substrate, the first light-emitting diode comprising a first active layer;

a second light-emitting diode on the substrate, the second light-emitting diode comprising a second active layer; and

a reflective layer located over the substrate between the first light-emitting diode and the second light-emitting diode, the reflective layer comprising a top surface closer to the substrate than the first active layer.

2. The light-generating device of claim 1, wherein the reflective layer comprises aluminum, silver, or other reflective materials.

3. The light-generating device of claim 1, wherein the first light-emitting diode is configured to emit a light with a first wavelength and a width of the first light-emitting diode is comparable with the first wavelength.

4. The light-generating device of claim 1, further comprising spacers located along sidewalls of the first light-emitting diode.

5. The light-generating device of claim 1, wherein the substrate is a light absorbing substrate.

6. The light-generating device of claim 1, further comprising a light-transmissive material over the reflective layer between the first light-emitting diode and the second light-emitting diode.

7. A light-generating device comprising:

a substrate;

a reflective layer over portions of the substrate, the reflective layer having a first thickness; and

a plurality of light-emitting diodes extending through the reflective layer to the substrate, each of the plurality of light-emitting diodes comprising an active layer that is located a first distance from the substrate, the first distance being greater than the first thickness.

8. The light-generating device of claim 7, wherein the reflective layer comprises aluminum, silver, or other reflective materials.

9. The light-generating device of claim 7, wherein at least one of the plurality of light-emitting diodes has a width that is comparable with a wavelength of light emitted by the light-generating device.

10. The light-generating device of claim 7, further comprising spacers located along sidewalls of the plurality of light-emitting diodes.

11. The light-generating device of claim 7, wherein the substrate is a light-absorbing substrate.

12. The light-generating device of claim 7, further comprising a light-transmissive material over the reflective layer between adjacent ones of the plurality of light-emitting diodes.

13. The light-generating device of claim 7, wherein each of the plurality of light-emitting diodes is in the shape of a circle, a rectangle, an ellipse, a triangle, or a hexagon.

14. A method for forming a light-generating device, the method comprising:

providing a substrate;

forming a plurality of light-emitting diodes on the substrate, each of the plurality of light-emitting diodes comprising an active layer; and

forming a reflective layer on the substrate;

wherein the reflective layer is located between adjacent ones of the plurality of light-emitting diodes and below the active layers.

15. The method of claim 14, wherein the reflective layer comprises aluminum, silver, or other reflective materials.

16. The method of claim 14, wherein at least one of the plurality of light-emitting diodes is configured to emit a light with a first wavelength, the at least one of the plurality of light-emitting diodes having a width that is comparable with the first wavelength.

17. The method of claim 14, wherein the forming a reflective layer includes forming spacers along sidewalls of the plurality of light-emitting diodes.

18. The method of claim 17, further comprising filling an area between the spacers and over the reflective layer with a light-transmissive material.

19. The method of claim 18, further comprising planarizing the light-transmissive material, the planarizing step also substantially exposing top surfaces of the plurality of light-emitting diodes.

20. The method of claim 14, wherein the forming a plurality of light-emitting diodes comprises:

forming a first contact layer;

forming an active layer over the first contact layer;

forming a second contact layer over the active layer;

forming a hard mask over the second contact layer, the hard mask exposing portions of the second contact layer; and

etching the exposed portions of the second contact layer, the active layer, and the first contact layer to form the plurality of light-emitting diodes.