Bonding pad for gallium nitride-based light-emitting device

• US 20040000670A1
• Filed: 06/28/2002
• Published: 01/01/2004
• Est. Priority Date: 06/28/2002
• Status: Active Grant

• Current Assignee: Kopin Corporation
• Original Assignee: Kopin Corporation
• Inventors: Tsaur, Bor-Yeu, Fan, John C.C., Choi, Hong K., Oh, Steve Tchang-Hun
• Granted Patent: US 7,002,180 B2
• Time in Patent Office: Days
• US Class Current: 257/76
• CPC Class Codes: H01L 33/40 Materials therefor

Abstract

A bonding pad for an electrode is in contact with p-type gallium nitride-based semiconductor material that includes aluminum. The bonding pad may also includes one or more metals selected from the group consisting of palladium, platinum, nickel and gold. The bonding pad can be used to attach a bonding wire to the p-electrode in a semiconductor device, such as a light-emitting diode or a laser diode without causing degradation of the light-transmission and ohmic properties of the electrode. The bonding pad may be formed of substantially the same material as an electrode in making an ohmic contact with n-type gallium nitride-based semiconductor material (n-electrode). This allows the bonding pad and the n-electrode to be formed simultaneously when manufacturing a gallium nitride-based light-emitting device which substantially reduces the cost to manufacture the device.

Claims

1. A semiconductor device comprising:

a substrate having a first major surface;

a semiconductor device structure over the first major surface of the substrate, the device structure comprising an n-type gallium nitride-based semiconductor layer, and a p-type gallium nitride-based semiconductor layer over the n-type semiconductor layer;

a first electrode in electrical contact with the n-type semiconductor layer;

a second electrode in contact with the p-type semiconductor layer; and

a bonding pad in contact with the second electrode, the bonding pad comprising a metallic material including aluminum.

2. The device of claim 1, wherein the metallic material of the bonding pad additionally comprises a metal selected from the group consisting of palladium, platinum, nickel and combinations thereof.

3. The device of claim 2, wherein the metallic material of the bonding pad additionally comprises palladium.

4. The device of claim 3, wherein the metallic material of the bonding pad comprises a layer of palladium in contact with the second electrode, and a layer of aluminum over the palladium layer.

5. The device of claim 1, wherein metallic material of the bonding pad additionally comprises gold.

6. The device of claim 1, wherein the bonding pad comprises a three layer metallic material, including a layer of palladium in contact with the second electrode, and a layer each of aluminum and gold over the palladium.

7. The device of claim 1, wherein the second electrode is substantially light transmissive.

8. The device of claim 1, wherein the first electrode and the bonding pad comprise substantially the same metallic material.

9. The device of claim 1, further comprising an active region of a semiconductor material between the n-type semiconductor layer and the p-type semiconductor layer.

10. The device of claim 9, wherein the active region has a single quantum-well structure.

11. The device of claim 9, wherein the active region has a multiple quantum-well structure.

12. A method for producing a semiconductor device comprising:

providing a substrate having a first major surface;

providing a semiconductor device structure over the first major surface of the substrate, the device structure comprising an n-type gallium nitride-based semiconductor layer, and a p-type gallium nitride-based semiconductor layer over the n-type semiconductor layer;

providing a first electrode in electrical contact with the n-type semiconductor layer;

providing a second electrode in contact with the p-type semiconductor layer; and

forming a bonding pad in contact with the second electrode, the bonding pad comprising a metallic material including aluminum.

13. The method of claim 12, wherein the first electrode is comprised of a metallic material that is substantially identical to the metallic material comprising the bonding pad.

14. The method of claim 13, wherein the steps of providing the first electrode and of forming the bonding pad are performed substantially simultaneously.

15. The method of claim 12, wherein the metallic material comprising the bonding pad additionally comprises at least one of a metal selected from the group consisting of palladium, platinum and nickel.

16. The method of claim 12, wherein step of forming a bonding pad comprises forming a first layer of a metal selected from the group consisting of palladium, platinum and nickel in direct contact with the second electrode, and forming a layer of aluminum over the first layer.

17. The method of claim 16, wherein the step of forming a bonding pad further comprises forming a layer of gold over the layer of aluminum.

18. A semiconductor device comprising:

a substrate having a first major surface;

a semiconductor device structure over the first major surface of the substrate, the device structure comprising an n-type gallium nitride-based semiconductor layer, and a p-type gallium nitride-based semiconductor layer over the n-type semiconductor layer;

a first electrode in electrical contact with the n-type semiconductor layer;

a second electrode in contact with the p-type semiconductor layer; and

a bonding pad in contact with the second electrode, wherein the first electrode and the bonding pad are formed of substantially the same metallic material that includes aluminum.

19. The device of claim 18, wherein the first electrode and the bonding pad each comprise aluminum, gold and one or more metals selected from the group consisting of palladium, platinum and nickel.

20. A method for producing a semiconductor device comprising:

providing a substrate having a first major surface;

providing a semiconductor device structure over the first major surface of the substrate, the device structure comprising an n-type gallium nitride-based semiconductor layer, and a p-type gallium nitride-based semiconductor layer over the n-type semiconductor layer;

forming a first electrode in electrical contact with the n-type semiconductor layer;

providing a second electrode in contact with the p-type semiconductor layer; and

forming a bonding pad in contact with the second electrode, wherein the first electrode and the bonding pad comprise substantially the same metallic material that includes aluminum and the first electrode and the bonding pad are formed simultaneously.

21. The method of claim 20, wherein the metallic material comprising the first electrode and the bonding pad additionally comprises at least one of palladium, platinum or nickel.

22. The method of claim 20, wherein steps of forming the first electrode and forming the bonding pad comprise:

simultaneously forming a first layer of the first electrode of palladium, platinum or nickel in direct contact with the n-type gallium nitride based semiconductor layer and a first layer of the bonding pad of palladium, platinum or nickel in direct contact with the second electrode; and

simultaneously forming a layer of aluminum over the first layer in contact with the n-type gallium nitride based semiconductor layer and a layer of aluminum over the first layer in contact with the second electrode.

23. The method of claim 22, wherein the steps of forming the first electrode and forming the bonding pad further comprises simultaneously forming a layer of gold over each of the layers of aluminum.

24. The method of claim 23, wherein the steps of forming the first electrode and forming the bonding pad further comprise annealing the first electrode and the bonding pad by heating the first electrode and the bonding pad to a temperature of at least about 350°

C.

25. A gallium nitride-based semiconductor device comprising:

a first electrode in electrical contact with the n-type gallium nitride-based semiconductor layer;

a second electrode in contact with the p-type gallium nitride-based semiconductor layer; and

a bonding pad in contact with the second electrode, the bonding pad comprising a metallic material including aluminum.