Light emitting diodes including integrated backside reflector and die attach

Patent metadata

Field	Value
Publication number	US-9437785-B2
Application number	US-53860209-A
Country	US
Kind code	B2
Filing date	Aug 10, 2009
Priority date	Aug 10, 2009
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

Light emitting diodes include a silicon carbide substrate having first and second opposing faces, a diode region on the first face, anode and cathode contacts on the diode region opposite the silicon carbide substrate and a hybrid reflector on the silicon carbide substrate opposite the diode region. The hybrid reflector includes a transparent layer having an index of refraction that is lower than the silicon carbide substrate, and a reflective layer on the transparent layer, opposite the substrate. A die attach layer may be provided on the hybrid reflector, opposite the silicon carbide substrate. A barrier layer may be provided between the hybrid reflector and the die attach layer.

First claim

What is claimed is:

1. A light emitting diode comprising:
a silicon carbide substrate having first and second opposing faces and oblique sidewalls therebetween;
a diode region on the first face and including therein an n-type layer and a p-type layer;
an anode contact that ohmically contacts the p-type layer and extends on the diode region opposite the silicon carbide substrate;
a cathode contact that ohmically contacts the n-type layer and also extends on the diode region opposite the silicon carbide substrate;
a layer comprising silicon dioxide on the second face of the silicon carbide substrate; and
a layer comprising aluminum on the layer comprising silicon dioxide, opposite the silicon carbide substrate;
wherein the layer comprising silicon dioxide and the layer comprising aluminum do not extend onto the oblique sidewalls of the silicon carbide substrate.

2. A light emitting diode according to claim 1 further comprising:
a layer comprising gold on the layer comprising aluminum, opposite the layer comprising silicon dioxide, wherein the layer comprising gold does not extend onto the oblique sidewalls of the silicon carbide substrate.

3. A light emitting diode according to claim 2 wherein the layer comprising gold comprises:
a first layer comprising gold-tin alloy on the layer comprising aluminum, opposite the layer comprising silicon dioxide; and
a second layer comprising elemental gold on the first layer comprising gold-tin alloy, opposite the layer comprising aluminum.

4. A light emitting diode according to claim 2 wherein the layer comprising gold comprises a layer comprising gold-tin alloy.

5. A light emitting diode according to claim 2 further comprising:
a layer comprising platinum between the layer comprising aluminum and the layer comprising gold,
wherein the layer comprising platinum does not extend onto the oblique sidewalls of the silicon carbide substrate.

6. A light emitting diode according to claim 5 further comprising:
a layer comprising titanium between the layer comprising platinum and the layer comprising aluminum; and
a layer comprising nickel between the layer comprising platinum and the layer comprising gold,
wherein the layer comprising titanium and the layer comprising nickel do not extend onto the oblique sidewalls of the silicon carbide substrate.

7. A light emitting diode according to claim 6 wherein the layers comprising silicon dioxide, aluminum, gold, platinum, titanium and nickel are all thin film layers on the silicon carbide substrate to provide an integrated backside reflector and die attach for the light emitting diode.

8. A light emitting diode according to claim 2 wherein the layers comprising silicon dioxide, aluminum and gold are all thin film layers on the silicon carbide substrate to provide an integrated backside reflector and die attach for the light emitting diode.

9. A light emitting diode comprising:
a silicon carbide substrate having first and second opposing faces and oblique sidewalls therebetween;
a diode region on the first face;
anode and cathode contacts on the diode region opposite the silicon carbide substrate;
a hybrid reflector on the silicon carbide substrate opposite the diode region, the hybrid reflector comprising a transparent layer having an index of refraction that is lower than the silicon carbide substrate and a reflective layer on the transparent layer, opposite the substrate, wherein the transparent layer comprises silicon dioxide;
wherein the hybrid reflector does not extend onto the oblique sidewalls of the silicon carbide substrate.

10. A light emitting diode according to claim 9 further comprising:
a die attach layer on the hybrid reflector, opposite the silicon carbide substrate, wherein the die attach layer does not extend onto the oblique sidewalls of the silicon carbide substrate.

11. A light emitting diode according to claim 10 further comprising a barrier layer between the hybrid reflector and the die attach layer, wherein the barrier layer does not extend onto the oblique sidewalls of the silicon carbide substrate.

12. A light emitting diode according to claim 11 wherein the reflective layer comprises aluminum, the die attach layer comprises gold-tin alloy and the barrier layer comprises platinum.

13. A light emitting diode according to claim 11 wherein the transparent layer, the reflective layer, the die attach layer and the barrier layer are all thin film layers on the silicon carbide substrate to provide an integrated backside reflector and die attach for the light emitting diode.

14. A light emitting diode according to claim 9 wherein the silicon carbide substrate has an index of refraction of about 2.75 and the transparent layer has an index of refraction of about 1.5.

15. An integrated backside reflector and die attach for a light emitting diode that includes a silicon carbide substrate having first and second opposing faces and oblique sidewalls therebetween, a diode region on the first face and anode and cathode contacts on the diode region opposite the silicon carbide substrate; the integrated backside reflector and die attach comprising:
a hybrid reflector on the silicon carbide substrate opposite the diode region, the hybrid reflector comprising a transparent layer having an index of refraction that is lower than the silicon carbide substrate and a reflective layer comprising metal on the transparent layer, opposite the substrate, wherein the transparent layer comprises silicon dioxide;
a die attach layer comprising metal on the reflective layer, opposite the transparent layer; and
a barrier layer between the hybrid reflector and the die attach layer,
wherein the hybrid reflector, the die attach layer and the barrier layer do not extend onto the oblique sidewalls of the silicon carbide substrate.

16. An integrated backside reflector and die attach for a light emitting diode according to claim 15 wherein the reflective layer reflective layer comprises aluminum, the die attach layer comprises gold-tin alloy and the barrier layer comprises platinum.

17. An integrated backside reflector and die attach for a light emitting diode according to claim 15 wherein the transparent layer, the reflective layer, the die attach layer and the barrier layer are all thin film layers on the silicon carbide substrate.

18. An integrated backside reflector and die attach for a light emitting diode that includes a silicon carbide substrate having first and second opposing faces and oblique sidewalls therebetween, a diode region on the first face and anode and cathode contacts on the diode region opposite the silicon carbide substrate; the integrated backside reflector and die attach comprising:
a hybrid reflector on the silicon carbide substrate opposite the diode region, the hybrid reflector comprising a transparent layer having an index of refraction that is lower than the silicon carbide substrate and a reflective layer comprising metal on the transparent layer, opposite the substrate, wherein the transparent layer comprises silicon dioxide; and
a die attach layer comprising metal on the reflective layer, opposite the transparent layer;
wherein the transparent layer, the reflective layer and the die attach layer are all thin film layers on the silicon carbide substrate that do not extend onto the oblique sidewalls of the silicon carbide substrate.

19. An integrated backside reflector and die attach for a light emitting diode according to claim 18 wherein the silicon carbide substrate has an index of refraction of abou

Assignees

• Bergmann Michael John
• Haberern Kevin Ward
• Williams Bradley E
• Parker Winston T
• Pun Arthur Fong-Yuen
• Suh Doowon
• Donofrio Matthew
• Cree Inc

Inventors

• Bergmann Michael John
• Haberern Kevin Ward
• Williams Bradley E
• Parker Winston T
• Pun Arthur Fong-Yuen
• Suh Doowon
• Donofrio Matthew

Classifications

• H10W72/884

  Die-attach connectors and bond wires · CPC title

• H10H20/819

  characterised by their shape, e.g. curved or truncated substrates · CPC title

• H10H20/01335

  the light-emitting regions comprising nitride materials · CPC title

• H10H20/841 Primary

  Reflective coatings, e.g. dielectric Bragg reflectors · CPC title

• H01L33/007

  Electricity · mapped topic