Semiconductor device and method for manufacturing the same

1. A method for manufacturing a semiconductor device comprising:

forming a layer in contact with a first semiconductor layer of an n type including a nitride semiconductor, the layer including Al, Au and Ni;

performing heat treatment in an inert gas atmosphere on the first semiconductor layer and the layer including the Al, Au and Ni to form a first metal layer including an alloy including Al, Au and Ni;

forming a second metal layer including a metal different from Al on the first metal layer; and

forming an insulating layer at a temperature of 350° C. or more on the second metal layer, wherein

a ratio of Ni in the alloy is not less than 0.05 and not more than 0.14,

a ratio of Al in the alloy is not less than 0.14 and not more than 0.34,

a ratio of Au in the alloy is not less than 0.55 and not more than 0.84, and

a total of the ratio of the Ni, the ratio of the Al, and the ratio of the Au is 1.

2. The method according to claim 1 , further comprising forming a counter conductive layer on the insulating layer,

the counter conductive layer being electrically connected to a second semiconductor layer of a p type away from the first semiconductor layer, the second semiconductor layer including a nitride semiconductor, a light emitting layer being disposed between the first semiconductor layer and the second semiconductor layer.

3. The method according to claim 1 , wherein the heat treatment in the inert gas atmosphere includes heat treatment at a temperature of not less than 400° C. and not more than 900° C.

4. The method according to claim 1 , wherein the inter gas includes nitrogen.

5. The method according to claim 1 , wherein the insulating layer is silicon oxide.

6. The method according to claim 1 , wherein the forming the second metal layer includes

forming a first Ti layer on the first metal layer,

forming a Pt layer on the first Ti layer, and

forming an Au layer on the Pt layer.

7. The method according to claim 6 , wherein the forming the second metal layer further includes

forming a second Ti layer on the Au layer.

8. A method for manufacturing a semiconductor device comprising:

forming a layer in contact with a first semiconductor layer of an n type including a nitride semiconductor, the layer including Al and Au;

performing heat treatment in an inert gas atmosphere on the first semiconductor layer and the layer including the Al and Au to form a first metal layer including an alloy including Al and Au;

forming a second metal layer including a metal different from Al on the first metal layer; and

forming an insulating layer at a temperature of 350° C. or more on the second metal layer, wherein

a ratio of Al in the alloy is not less than 0.15 and not more than 0.24, and

a total of the ratio of the Al and the ratio of the Au is 1.

9. The method according to claim 8 , further comprising forming a counter conductive layer on the insulating layer,

the counter conductive layer being electrically connected to a second semiconductor layer of a p type away from the first semiconductor layer, the second semiconductor layer including a nitride semiconductor, a light emitting layer being disposed between the first semiconductor layer and the second semiconductor layer.

10. The method according to claim 8 , wherein the heat treatment in the inert gas atmosphere includes heat treatment at a temperature of not less than 400° C. and not more than 900° C.

11. The method according to claim 8 , wherein the inter gas includes nitrogen.

12. The method according to claim 8 , wherein the insulating layer is silicon oxide.

13. The method according to claim 8 , wherein the forming the second metal layer includes

forming a first Ti layer on the first metal layer,

forming a Pt layer on the first Ti layer, and

forming an Au layer on the Pt layer.

14. The method according to claim 13 , wherein the forming the second metal layer further includes

forming a second Ti layer on the Au layer.