Method of fabricating vertical devices using a metal support film
View Patent ↗A method of fabricating semiconductor devices, such as GaN LEDs, on insulating substrates, such as sapphire. Semiconductor layers are produced on the insulating substrate using normal techniques. Trenches that define the boundaries of the individual devices are formed through the semiconductor layers and into the insulating substrate, beneficially by inductive coupled plasma reactive ion etching. A first support structure is attached to the semiconductor layers. The hard substrate is then removed, beneficially by laser lift off. A second supporting structure, preferably conductive, is substituted for the hard substrate and the first supporting structure is removed. Individual devices are then diced, beneficially by etching through the second supporting structure. A protective photo-resist layer can protect the semiconductor layers from the attachment of the first support structure. A conductive bottom contact (possibly reflective) can be inserted between the second supporting structure and the semiconductor layers.
1. A vertical topology light emitting diode, comprising:
an adhesion structure comprising a first metal layer having a first surface and a second metal layer having a second surface;
a conductive support structure over the first surface;
a reflective structure over the second surface, the reflective structure also serving as a first electrical contact;
a semiconductor device over the reflective structure, the semiconductor device comprising a first-type GaN-based layer, an active layer on the first-type GaN-based layer, and a second-type GaN-based layer on the active layer; and
a second electrical contact over a surface of the semiconductor device,
wherein the reflective structure and the second electrical contact are located over opposite surfaces of the semiconductor device, respectively,
wherein the reflective structure comprises a reflective metal layer over the second surface of the adhesion structure and a metal contact directly on a surface of the reflective metal layer, wherein the reflective metal layer is thicker than the metal contact, wherein the metal contact contacts the first-type GaN-based layer,
wherein the reflective structure reflects light from the semiconductor device on the surface of the reflective metal layer, wherein the surface of the reflective metal layer is a dominant reflective surface,
wherein the reflective metal layer is a pure metal layer,
wherein the first metal layer is thicker than the second metal layer, and
wherein the reflective metal layer of the reflective structure and the first metal layer of the adhesion structure comprise different materials and wherein the reflective metal layer and the metal contact comprise different materials.
2. The vertical topology light emitting diode according to claim 1 , wherein the adhesion structure comprises at least one of Au or Cr.
3. The vertical topology light emitting diode according to claim 1 , wherein the conductive support structure is less than about 100 microns thick.
4. The vertical topology light emitting diode according to claim 1 , wherein the conductive support structure comprises at least one of Cu, Al, or Au.
5. The vertical topology light emitting diode according to claim 1 , wherein the active layer comprises AlInGaN.
6. The vertical topology light emitting diode according to claim 1 , wherein the active layer comprises a quantum well.
7. The vertical topology light emitting diode according to claim 1 , wherein the second electrical contact comprises a second-type transparent contact on the second-type GaN-based layer.
8. A vertical topology light emitting diode, comprising:
a reflective structure comprising a reflective metal layer having a first side and a metal contact having a second side, the reflective structure also serving as a first electrical contact, wherein the metal contact is directly on a surface of the reflective metal layer, wherein the reflective metal layer is thicker than the metal contact, wherein the reflective metal layer is a pure metal layer, and wherein the reflectivity of the reflective metal layer is higher than the reflectivity of the metal contact;
an adhesion structure over the first side of the reflective structure, the adhesion structure comprising a first metal layer and a second metal layer;
a conductive support structure over the adhesion structure;
a semiconductor device over the second side of the reflective structure, the semiconductor device comprising a first-type GaN-based layer, an active layer, and a second-type GaN-based layer; and
a second electrical contact over a surface of the semiconductor device,
wherein the reflective structure reflects light from the semiconductor device on the surface of the reflective metal layer, wherein the surface of the reflective metal layer is a dominant reflective surface, wherein the reflective structure and the second electrical contact are located over opposite surfaces of the semiconductor device, respectively, and wherein the metal contact contacts the first-type GaN-based layer,
wherein the first metal layer is located proximate to the conductive support structure and the second metal layer is located proximate to the reflective structure, wherein the first metal layer is thicker than the second metal layer, and wherein the reflective metal layer of the reflective structure and the first metal layer of the adhesion structure comprise different materials and wherein the reflective metal layer and the metal contact comprise different materials.
9. The vertical topology light emitting diode according to claim 8 , wherein the adhesion structure comprises at least one of Au or Cr.
10. The vertical topology light emitting diode according to claim 1 , wherein the reflective metal layer comprises aluminum and/or the metal contact comprises titanium.
11. The vertical topology light emitting diode according to claim 8 , wherein the reflective metal layer comprises aluminum and/or the metal contact comprises titanium.
12. The vertical topology light emitting diode according to claim 1 , wherein the second electrical contact comprises at least a second-type contact on the second-type GaN-based layer.
13. The vertical topology light emitting diode according to claim 8 , wherein the conductive support structure is less than about 100 microns thick.
14. The vertical topology light emitting diode according to claim 8 , wherein a shortest distance from a reflecting surface of the reflective structure to the surface of the semiconductor device is less than 5 microns.
15. The vertical topology light emitting diode according to claim 1 , wherein a shortest distance from a reflecting surface of the reflective structure to the surface of the semiconductor device is less than 5 microns.
16. The vertical topology light emitting diode according to claim 1 , wherein the conductive support structure comprises a metal support layer.
17. The vertical topology light emitting diode according to claim 1 , wherein the first metal layer contacts the conductive support structure.
18. The vertical topology light emitting diode according to claim 1 , wherein the second metal layer contacts the reflective structure.
19. The vertical topology light emitting diode according to claim 1 , wherein the second metal layer comprises a Cr adhesion layer.
20. The vertical topology light emitting diode according to claim 1 , wherein the adhesion structure and the conductive support structure have surfaces that face each other, and wherein the areas of the surfaces are substantially the same.
21. The vertical topology light emitting diode according to claim 1 , wherein the adhesion structure contacts the reflective structure.
22. The vertical topology light emitting diode according to claim 1 , wherein the second electrical contact comprises a transparent contact.
23. The vertical topology light emitting diode according to claim 1 , wherein the conductive support structure comprises thermally conductive material.
24. The vertical topology light emitting diode according to claim 1 , wherein the conductive support structure comprises electrically conductive material.
25. The vertical topology light emitting diode according to claim 8 , wherein the first metal layer contacts the conductive support structure.
26. The vertical topology light emitting diode according to claim 8 , wherein the second metal layer contacts the reflective structure.
27. The vertical topology light emitting diode according to claim 8 , wherein the first metal layer comprises an Au adhesion layer.
28. The vertical topology light emitting diode according to claim 8 , wherein the second metal layer comprises a Cr adhesion layer.
29. The vertical topology light emitting diode according to claim 8 , wherein the adhesion structure and the conductive support structure have surfaces that face each other, and wherein the areas of the surfaces are substantially the same.
30. The vertical topology light emitting diode according to claim 8 , wherein the adhesion structure contacts the reflective structure.
31. The vertical topology light emitting diode according to claim 8 , wherein the conductive support structure comprises thermally conductive material.
32. The vertical topology light emitting diode according to claim 8 , wherein the conductive support structure comprises electrically conductive material.
33. The vertical topology light emitting diode according to claim 8 , wherein the conductive support structure comprises at least one of Cu, Al, or Au.
34. The vertical topology light emitting diode according to claim 8 , wherein the conductive support structure comprises a metal support layer.
35. The vertical topology light emitting diode according to claim 1 , wherein the first metal layer is located proximate to the conductive support structure and the second metal layer is located proximate to the reflective structure.
36. The vertical topology light emitting diode according to claim 1 , wherein the first metal layer comprises an Au adhesion layer.
37. The vertical topology light emitting diode according to claim 1 , wherein the reflective structure is in direct contact with the semiconductor device.
38. The vertical topology light emitting diode according to claim 8 , wherein the reflective structure is in direct contact with the semiconductor device.
39. The vertical topology light emitting diode according to claim 1 , wherein the reflective metal layer of the reflective structure contacts the second metal layer of the adhesion structure.
40. The vertical topology light emitting diode according to claim 8 , wherein the reflective metal layer of the reflective structure contacts the second metal layer of the adhesion structure.
41. The vertical topology light emitting diode according to claim 8 , wherein the second electrical contact comprises a transparent contact.
42. The vertical topology light emitting diode according to claim 1 , wherein the conductive support structure comprises a support layer.
43. The vertical topology light emitting diode according to claim 8 , wherein the conductive support structure comprises a support layer.
44. The vertical topology light emitting diode according to claim 1 , wherein the reflective metal layer is a single layer.
45. The vertical topology light emitting diode according to claim 8 , wherein the reflective metal layer is a single layer.
46. The vertical topology light emitting diode according to claim 1 , wherein the first-type is n-type and the second-type is p-type.
47. The vertical topology light emitting diode according to claim 1 , wherein the metal contact is arranged such that electrical current can flow across a contacting surface between the metal contact and the first-type GaN-based layer.
48. The vertical topology light emitting diode according to claim 8 , wherein the first-type is n-type and the second-type is p-type.
49. The vertical topology light emitting diode according to claim 8 , wherein the metal contact is arranged such that electrical current can flow across a contacting surface between the metal contact and the first-type GaN-based layer.
50. The vertical topology light emitting diode according to claim 1 , wherein the surface of the reflective metal layer is a dominant reflective surface with respect to a surface inside of the reflective metal layer.
51. The vertical topology light emitting diode according to claim 8 , wherein the surface of the reflective metal layer is a dominant reflective surface with respect to a surface inside of the reflective metal layer.