Ohmic contact to semiconductor device
View Patent ↗Embodiments of an ohmic contact structure for a Group III nitride semiconductor device and methods of fabrication thereof are disclosed. In one embodiment, the ohmic contact structure has less than or equal to 5%, more preferably less than or equal to 2%, more preferably less than or equal to 1.5%, and even more preferably less than or equal to 1% degradation for 1000 hours High Temperature Soak (HTS) at 300 degrees Celsius. In another embodiment, the ohmic contact structure additionally or alternatively has less than or equal to 10% degradation, more preferably less than or equal to 7.5% degradation, more preferably less than or equal to 6% degradation, more preferably less than or equal to 5% degradation, and even more preferably less than 3% degradation for 1000 hours High Temperature operating Life (HToL) at 225 degrees Celsius and 50 milliamps (mA) per millimeter (mm).
1. A semiconductor device comprising:
a Group III nitride semiconductor structure; and
an ohmic contact structure on a surface of the Group III nitride semiconductor structure, the ohmic contact structure having less than or equal to 5% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
2. The semiconductor device of claim 1 wherein the ohmic contact structure has less than or equal to 2% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
3. The semiconductor device of claim 1 wherein the ohmic contact structure has less than or equal to 1.5% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
4. The semiconductor device of claim 1 wherein the ohmic contact structure has less than or equal to 1% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
5. The semiconductor device of claim 1 wherein the ohmic contact structure has less than or equal to 5% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter.
6. The semiconductor device of claim 1 wherein the ohmic contact structure has one of a group consisting of: less than or equal to 10% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 7.5% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 6% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 5% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, and less than or equal to 3% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter.
7. The semiconductor device of claim 1 wherein the ohmic contact structure comprises: a titanium layer on the surface of the Group III nitride semiconductor structure; a nickel silicide layer on a surface of the titanium layer opposite the Group III nitride semiconductor structure; and a metal cap layer on a surface of the nickel silicide layer opposite the titanium layer.
8. The semiconductor device of claim 1 wherein the ohmic contact structure comprises: a titanium layer on the surface of the Group III nitride semiconductor structure; an alternating series of one or more silicon layers and one or more nickel layers on a surface of the titanium layer opposite the Group III nitride semiconductor structure; and a metal cap layer on a surface of the alternating series of the one or more silicon layers and the one or more nickel layers opposite the titanium layer.
9. The semiconductor device of claim 1 wherein the Group III nitride semiconductor structure comprises at least one of gallium nitride (GaN) and aluminum gallium nitride (AIGaN).
10. The semiconductor device of claim 7 wherein the metal cap layer is formed of one of a group consisting of: tellurium (Te), platinum (Pt), palladium (Pd), vanadium (V), tungsten (W), gold (Au), iridium (Ir), and rhodium (Rh).
11. The semiconductor device of claim 8 wherein the alternating series of the one or more silicon layers and the one or more nickel layers comprises: a silicon layer on the surface of the titanium layer opposite the Group III nitride semiconductor structure; and a nickel layer on a surface of the silicon layer opposite the titanium layer; wherein the metal cap layer is on a surface of the nickel layer opposite the silicon layer.
12. The semiconductor device of claim 8 wherein the alternating series of the one or more silicon layers and the one or more nickel layers comprises: a first silicon layer on the surface of the titanium layer opposite the Group III nitride semiconductor structure; a first nickel layer on a surface of the first silicon layer opposite the titanium layer; a second silicon layer on a surface of the first nickel layer opposite the first silicon layer; a second nickel layer on a surface of the second silicon layer opposite the first nickel layer; a third silicon layer on a surface of the second nickel layer opposite the second silicon layer; and a third nickel layer on a surface of the third silicon layer opposite the second nickel layer; wherein the metal cap layer is on a surface of the third nickel layer opposite the third silicon layer.
13. The semiconductor device of claim 8 wherein the metal cap layer is formed of one of a group consisting of: tellurium (Te), platinum (Pt), palladium (Pd), vanadium (V), tungsten (W), gold (Au), iridium (Ir), and rhodium (Rh).
14. The semiconductor device of claim 8 wherein an atomic weight percentage of silicon in the alternating series of the one or more silicon layers and the one or more nickel layers is in a range of and including 45% to 60%.
15. The semiconductor device of claim 8 wherein a ratio of a combined thickness of the one or more silicon layers to a combined thickness of the one or more nickel layers is 2:1.
16. The semiconductor device of claim 8 wherein a combined thickness of the one or more silicon layers is in a range of and including 1500 Angstroms+5%, and a combined thickness of the one or more nickel layers is in a range of and including 750 Angstroms+5%.
17. The semiconductor device of claim 8 wherein the alternating series of the one or more silicon layers and the one or more nickel layers is an alternating series of two or more silicon layers and two or more nickel layers.
18. The semiconductor device of claim 16 wherein a thickness of the titanium layer is in a range of and including 200 Angstroms+5%, and a thickness of the metal cap layer is in a range of and including 125 Angstroms+5%.
19. A method of fabrication of an ohmic contact structure on a semiconductor device comprising: providing a Group III nitride semiconductor structure; and providing the ohmic contact structure on a surface of the Group III nitride semiconductor structure such that the ohmic contact structure experiences less than or equal to 5% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
20. The method of claim 19 wherein providing the ohmic contact structure comprises providing the ohmic contact structure on the surface of the Group III nitride semiconductor structure such that the ohmic contact structure experiences less than or equal to 2% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
21. The method of claim 19 wherein providing the ohmic contact structure comprises providing the ohmic contact structure on the surface of the Group III nitride semiconductor structure such that the ohmic contact structure experiences less than or equal to 1.5% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
22. The method of claim 19 wherein providing the ohmic contact structure comprises providing the ohmic contact structure on the surface of the Group III nitride semiconductor structure such that the ohmic contact structure experiences less than or equal to 1% degradation with respect to gap size after 1000 hours at 300 degrees Celsius.
23. The method of claim 19 wherein providing the ohmic contact structure comprises providing the ohmic contact structure on the surface of the Group III nitride semiconductor structure such that the ohmic contact structure experiences less than or equal to 5% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter.
24. The method of claim 19 wherein providing the ohmic contact structure comprises providing the ohmic contact structure on the surface of the Group III nitride semiconductor structure such that the ohmic contact structure experiences one of a group consisting of: less than or equal to 10% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 7.5% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 6% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 5% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, and less than or equal to 3% degradation with respect to gap size after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter.
25. The method of claim 19 wherein providing the ohmic contact structure comprises: providing a titanium layer on the surface of the Group III nitride semiconductor structure; providing a nickel silicide layer on a surface of the titanium layer opposite the Group III nitride semiconductor structure; and providing a metal cap layer on a surface of the nickel silicide layer opposite the titanium layer.
26. The method of claim 19 wherein providing the ohmic contact structure comprises: providing a titanium layer on the surface of the Group III nitride semiconductor structure; providing an alternating series of one or more silicon layers and one or more nickel layers on a surface of the titanium layer opposite the Group III nitride semiconductor structure; providing a metal cap layer on a surface of the alternating series of the one or more silicon layers and the one or more nickel layers opposite the titanium layer; and annealing the ohmic contact structure such that the alternating series of the one or more silicon layers and the one or more nickel layers form a nickel silicide layer.
27. The method of claim 19 wherein the Group III nitride semiconductor structure comprises at least one of gallium nitride (GaN) and aluminum gallium nitride (AIGaN).
28. The method of claim 25 wherein the metal cap layer is formed of one of a group consisting of: tellurium (Te), platinum (Pt), palladium (Pal), vanadium (V), tungsten (W), gold (Au), iridium (Ir), and rhodium (Rh).
29. The method of claim 26 wherein providing the alternating series of the one or more silicon layers and the one or more nickel layers comprises: providing a silicon layer on the surface of the titanium layer opposite the Group III nitride semiconductor structure; and providing a nickel layer on a surface of the silicon layer opposite the titanium layer; wherein providing the metal cap layer on the surface of the alternating series of the one or more silicon layers and the one or more nickel layers opposite the titanium layer comprises providing the metal cap layer on a surface of the nickel layer opposite the silicon layer.
30. The method of claim 26 wherein providing the alternating series of the one or more silicon layers and the one or more nickel layers comprises: providing a first silicon layer on the surface of the titanium layer opposite the Group III nitride semiconductor structure; providing a first nickel layer on a surface of the first silicon layer opposite the titanium layer; providing a second silicon layer on a surface of the first nickel layer opposite the first silicon layer; providing a second nickel layer on a surface of the second silicon layer opposite the first nickel layer; providing a third silicon layer on a surface of the second nickel layer opposite the second silicon layer; and providing a third nickel layer on a surface of the third silicon layer opposite the second nickel layer; wherein providing the metal cap layer on the surface of the alternating series of the one or more silicon layers and the one or more nickel layers opposite the titanium layer comprises providing the metal cap layer on a surface of the third nickel layer opposite the third silicon layer.
31. The method of claim 26 wherein the metal cap layer is formed of one of a group consisting of: tellurium (Te), platinum (Pt), palladium (Pd), vanadium (V), tungsten (W), gold (Au), iridium (Ir), and rhodium (Rh).
32. The method of claim 26 wherein an atomic weight percentage of silicon in the alternating series of the one or more silicon layers and the one or more nickel layers is in a range of and including 45% to 60%.
33. The method of claim 26 wherein a ratio of a combined thickness of the one or more silicon layers to a combined thickness of the one or more nickel layers is 2:1.
34. The method of claim 26 wherein a combined thickness of the one or more silicon layers is in a range of and including 1500 Angstroms+5%, and a combined thickness of the one or more nickel layers is in a range of and including 750 Angstroms+5%.
35. The method of claim 26 wherein the alternating series of the one or more silicon layers and the one or more nickel layers is an alternating series of two or more silicon layers and two or more nickel layers.
36. The method of claim 26 wherein annealing the ohmic contact structure comprises annealing the ohmic contact structure at a temperature at or below 600 degrees Celsius.
37. The method of claim 26 wherein annealing the ohmic contact structure comprises: annealing the ohmic contact structure at a first temperature in a range of and including 200 degrees Celsius to 400 degrees Celsius such that the alternating series of the one or more silicon layers and the one or more nickel layers form the nickel silicide layer; and annealing the ohmic contact structure at a second temperature that is higher than the first temperature and in a range of and including 500 degrees Celsius to 600 degrees Celsius to finalize the ohmic contact structure.
38. The method of claim 34 wherein a thickness of the titanium layer is in a range of and including 200 Angstroms+5%, and a thickness of the metal cap layer is in a range of and including 125 Angstroms+5%.
39. A semiconductor device comprising:
a Group III nitride semiconductor structure; and
an ohmic contact structure on a surface of the Group III nitride semiconductor structure, the ohmic contact structure having less than or equal to 10% degradation after 1000 hours at 225 degrees Celsius wherein the ohmic contact structure comprises:
a titanium layer on the surface of the Group III nitride semiconductor structure; and
a nickel silicide layer on a surface of the titanium layer opposite the Group III nitride semiconductor structure.
40. The semiconductor device of claim 39 wherein the ohmic contact structure has less than or equal to 7.5% degradation after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter.
41. The semiconductor device of claim 39 wherein the ohmic contact structure has less than or equal to 5% degradation after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter.
42. The semiconductor device of claim 39 wherein the ohmic contact structure has one of a group consisting of: less than or equal to 7.5% degradation after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 6% degradation after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, less than or equal to 5% degradation after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter, and less than or equal to 3% degradation after 1000 hours at 225 degrees Celsius and 50 milliamps per millimeter.