Method for manufacturing semiconductor device

1. A method for manufacturing a semiconductor device, comprising the steps of:

forming a first insulating film;

forming a source electrode, a drain electrode, and an oxide semiconductor film over the first insulating film, wherein the oxide semiconductor film is electrically connected to the source electrode and the drain electrode;

performing first oxygen doping treatment on the oxide semiconductor film;

forming a second insulating film over the oxide semiconductor film;

performing second oxygen doping treatment on the second insulating film; and

forming a gate electrode over the oxide semiconductor film with the second insulating film interposed therebetween.

2. The method according to claim 1 , wherein the oxide semiconductor film is formed over the source electrode and the drain electrode.

3. The method according to claim 1 , wherein the source electrode and the drain electrode are formed over the oxide semiconductor film.

4. The method according to claim 1 , further comprising a step of forming a third insulating film over the gate electrode.

5. The method according to claim 1 , further comprising the step of forming a fourth insulating film,

wherein the first insulating film is formed over the fourth insulating film,

and

wherein the first insulating film comprises a component which is the same as that of the oxide semiconductor film.

6. The method according to claim 1 , further comprising the step of forming a fourth insulating film,

wherein the first insulating film is formed over the fourth insulating film,

wherein the first insulating film comprises a component which is the same as that of the oxide semiconductor film, and

wherein the fourth insulating film comprises a component which is different from that of the oxide semiconductor film.

7. The method according to claim 1 , further comprising the step of forming a fourth insulating film over the second insulating film,

wherein the second insulating film comprises a component which is the same as that of the oxide semiconductor film.

8. The method according to claim 1 , further comprising the step of forming a fourth insulating film over the second insulating film,

wherein the second insulating film comprises a component which is the same as that of the oxide semiconductor film, and

wherein the fourth insulating film comprises a component which is different from that of the oxide semiconductor film.

9. The method according to claim 1 , wherein the oxide semiconductor film comprises gallium as a component.

10. The method according to claim 1 , wherein the oxide semiconductor film comprises indium, gallium, and zinc.

11. A method for manufacturing a semiconductor device, comprising the steps of:

forming a first gallium oxide film;

forming a source electrode, a drain electrode, and an oxide semiconductor film over the first gallium oxide film, wherein the oxide semiconductor film is electrically connected to the source electrode and the drain electrode;

performing first oxygen doping treatment on the oxide semiconductor film;

forming a second gallium oxide film over the oxide semiconductor film;

performing second oxygen doping treatment on the second gallium oxide film; and

forming a gate electrode over the oxide semiconductor film with the second gallium oxide film interposed therebetween.

12. The method according to claim 11 , wherein the oxide semiconductor film is formed over the source electrode and the drain electrode.

13. The method according to claim 11 , wherein the source electrode and the drain electrode are formed over the oxide semiconductor film.

14. The method according to claim 11 , further comprising a step of forming a third insulating film over the gate electrode.

15. The method according to claim 11 , further comprising the step of forming a first insulating film, wherein the first gallium oxide film is formed over the first insulating film.

16. The method according to claim 11 , further comprising the step of forming a first insulating film,

wherein the first gallium oxide film is formed over the first insulating film, and

wherein the first insulating film comprises a component which is different from that of the oxide semiconductor film.

17. The method according to claim 11 , further comprising the step of forming a second insulating film over the second gallium oxide film.

18. The method according to claim 11 , further comprising the step of forming a second insulating film over the second gallium oxide film,

wherein the second insulating film comprises a component which is different from that of the oxide semiconductor film.

19. The method according to claim 11 , wherein the oxide semiconductor film comprises gallium as a component.

20. The method according to claim 11 , wherein the oxide semiconductor film comprises indium, gallium, and zinc.

21. The method according to claim 11 , further comprising the step of performing heat treatment on the oxide semiconductor film.

22. A method for manufacturing a semiconductor device, comprising the steps of:

forming a first insulating film;

forming a source electrode, a drain electrode, and an oxide semiconductor film over the first insulating film, wherein the oxide semiconductor film is electrically connected to the source electrode and the drain electrode;

performing heat treatment on the oxide semiconductor film;

performing first oxygen doping treatment on the oxide semiconductor film;

forming a second insulating film over the oxide semiconductor film;

performing second oxygen doping treatment on the second insulating film; and

forming a gate electrode over the oxide semiconductor film with the second insulating film interposed therebetween.

23. The method according to claim 22 , wherein the oxide semiconductor film is formed over the source electrode and the drain electrode.

24. The method according to claim 22 , wherein the source electrode and the drain electrode are formed over the oxide semiconductor film.

25. The method according to claim 22 , further comprising a step of forming a third insulating film over the gate electrode.

26. The method according to claim 22 ,

wherein the first insulating film comprises a fourth insulating film and a fifth insulating film over the fourth insulating film, and

wherein the fifth insulating film comprises a component which is the same as that of the oxide semiconductor film.

27. The method according to claim 22 ,

wherein the first insulating film comprises a fourth insulating film and a fifth insulating film over the fourth insulating film,

wherein the fifth insulating film comprises a component which is the same as that of the oxide semiconductor film, and

wherein the fourth insulating film comprises a component which is different from that of the oxide semiconductor film.

28. The method according to claim 22 ,

wherein the second insulating film comprises a sixth insulating film and a seventh insulating film over the sixth insulating film, and

wherein the sixth insulating film comprises a component which is the same as that of the oxide semiconductor film.

29. The method according to claim 22 ,

wherein the second insulating film comprises a sixth insulating film and a seventh insulating film over the sixth insulating film,

wherein the sixth insulating film comprises a component which is the same as that of the oxide semiconductor film, and

wherein the seventh insulating film comprises a component which is different from that of the oxide semiconductor film.

30. The method according to claim 22 , wherein the oxide semiconductor film comprises gallium as a component.

31. The method according to claim 22 , wherein the oxide semiconductor film comprises indium, gallium, and zinc.