Method of forming a gate insulator in group III-V nitride semiconductor devices

• US 20060121700A1
• Filed: 12/06/2004
• Published: 06/08/2006
• Est. Priority Date: 12/06/2004
• Status: Active Grant

• Current Assignee: Tekcore Co Limited (Tekcore)
• Original Assignee: Tekcore Co Limited (Tekcore)
• Inventors: Peng, Lung-Han, Lin, Jing-Yi, Wu, Han-Ming
• Granted Patent: US 7,253,061 B2
• Time in Patent Office: Days
• US Class Current: 438/483
• CPC Class Codes: H01L 21/02241 III-V semiconductor
• CPC Class Codes: H01L 21/02258 formation by anodic treatment, e.g. anodic oxidation
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/3143 composed of alternated layers or of mixtures of nitrides and oxides or of oxinitrides, e.g. formation of oxinitride by oxidation of nitride layers
• CPC Class Codes: H01L 21/31679 of AIII BV compounds
• CPC Class Codes: H01L 29/78681 having a semiconductor body comprising AIIIBV or AIIBVI or AIVBVI semiconductor materials, or Se or Te

Abstract

A method of forming a gate insulator in the manufacture of a semiconductor device comprises conducting a photo-assisted electrochemical process to form a gate-insulating layer on a gallium nitride layer of the semiconductor device, wherein the gate-insulating layer includes gallium oxynitride and gallium oxide, and performing a rapid thermal annealing process. The photo-assisted electrochemical process uses an electrolyte bath including buffered CH₃COOH at a pH between about 5.5 and 7.5. The rapid thermal annealing process is conducted in O₂ environment at a temperature between about 500° C. and 800° C.

Claims

1. A method of forming a gallium nitride semiconductor device, comprising:

forming an n-type gallium nitride layer over a substrate;

conducting a photo-assisted electrochemical process to form a gate-insulating layer on the n-type gallium nitride, wherein the gate-insulating layer includes gallium oxide and gallium oxynitride with a graded composition;

performing a thermal annealing process; and

forming a gate electrode on the gate-insulating layer.

2. The method according to claim 1, wherein conducting the photo-assisted electrochemical process includes immersing the substrate in an electrolyte bath including buffered acetic acid (CH₃COOH).

3. The method according to claim 2, wherein the acetic acid (CH₃COOH) is buffered with CH₃COONH₄.

4. The method according to claim 2, wherein the electrolyte bath has a pH value between about 5.5 and 7.5.

5. The method according to claim 2, wherein performing a photo-assisted electrochemical process includes emitting a radiation light with a wavelength between about 250 nm and 260 nm through the electrolyte bath.

6. The method according to claim 1, wherein the thermal annealing process is performed at a temperature between about 500°

C. and 800°

C.

7. The method according to claim 1, wherein the thermal annealing process is performed in O₂ environment.

8. The method according to claim 1, wherein the graded composition varies from about GaO_0.18N_0.82 to GaO_0.82N_0.18.

9. The method according to claim 1, wherein the gallium oxynitride is formed with a layer thickness between about 20 nm and 30 nm.

10. A method of forming an oxide compound on a semiconductor layer, comprising:

conducting a photo-assisted electrochemical process using an electrolyte bath with a pH between about 5.5 and 7.5 to form the oxide compound on the semiconductor layer; and

performing a thermal annealing process.

11. The method according to claim 10, wherein the electrolyte bath includes buffered acetic acid (CH₃COOH).

12. The method according to claim 11, wherein the acetic acid (CH₃COOH) is buffered with CH₃COONH₄.

13. The method according to claim 10, wherein conducting a photo-assisted electrochemical process includes emitting a radiation light having a wavelength between about 250 nm and 260 nm through the electrolyte bath.

14. The method according to claim 10, wherein the thermal annealing process is performed at a temperature between about 500°

C. and 800°

C.

15. The method according to claim 10, wherein the thermal annealing process is performed in O₂ environment.

16. The method according to claim 10, wherein the oxide compound includes gallium oxide, and the semiconductor layer includes gallium nitride.

17. The method according to claim 16, wherein conducting a photo-assisted electrochemical process forms a layer of gallium oxynitride with a graded composition between the gallium oxide layer and the semiconductor layer.

18. The method according to claim 17, wherein the graded composition varies from about GaO_0.18N_0.82 to GaO_0.82N_0.18.

19. The method according to claim 17, wherein the gallium oxynitride layer is formed with a layer thickness between about 20 nm and 30 nm.

20. A method of forming an oxide compound on a semiconductor layer, comprising:

conducting a photo-assisted electrochemical process to form the oxide compound layer over the semiconductor layer, wherein the photo-assisted electrochemical process uses an electrolyte bath including buffered acetic acid (CH₃COOH); and

performing a thermal annealing process.

21. The method according to claim 20, wherein the acetic acid (CH₃COOH) is buffered with CH₃COONH₄.

22. The method according to claim 20, wherein the electrolyte bath has a pH value between about 5.5 and 7.5.

23. The method according to claim 20, wherein conducting a photo-assisted electrochemical process includes emitting a radiation light having a wavelength between about 250 nm and 260 nm through the electrolyte bath.

24. The method according to claim 20, wherein the thermal annealing process is performed at a temperature between about 500°

C. and 800°

C.

25. The method according to claim 20, wherein the thermal annealing process is performed in O₂ environment.

26. The method according to claim 20, wherein the oxide compound includes gallium oxide, and the semiconductor layer includes gallium nitride.

27. The method according to claim 26, wherein conducting a photo-assisted electrochemical process forms a layer of gallium oxynitride with a graded composition between the gallium oxide layer and the semiconductor layer.

28. The method according to claim 27, wherein the graded composition varies from about GaO_0.18N_0.82 to GaO_0.82N_0.18.

29. The method according to claim 27, wherein the gallium oxynitride layer is formed with a layer thickness between about 20 nm and 30 nm.