Method for manufacturing semiconductor device
To provide a method for manufacturing a thin film transistor in which contact resistance between an oxide semiconductor layer and source and drain electrode layers is small, the surfaces of the source and drain electrode layers are subjected to sputtering treatment with plasma and an oxide semiconductor layer containing In, Ga, and Zn is formed successively over the source and drain electrode layers without exposure of the source and drain electrode layers to air.
1. A method for manufacturing a semiconductor device, the method comprising the steps of:
forming an insulating film;
performing a plasma treatment on the insulating film;
after performing the plasma treatment, forming an oxide semiconductor film over the insulating film; and
performing a heat treatment on the oxide semiconductor film,
wherein the plasma treatment is performed in an atmosphere comprising oxygen, and
wherein the oxide semiconductor film comprises indium and zinc.
2. The method according to claim 1 , comprising the step of:
forming a source electrode layer and a drain electrode layer over the insulating film,
wherein the plasma treatment is performed on the source electrode layer and the drain electrode layer, and
wherein the oxide semiconductor film is formed over the source electrode layer and the drain electrode layer.
3. The method according to claim 1 , wherein the oxide semiconductor film is formed without exposure to air after the plasma treatment is performed.
4. The method according to claim 1 , wherein the oxide semiconductor film comprises gallium.
5. The method according to claim 1 , wherein the atmosphere comprises an inert gas.
6. The method according to claim 1 , the method comprising the step of forming a gate electrode layer,
wherein the insulating film is formed over the gate electrode layer, and
wherein the oxide semiconductor film is formed to overlap the gate electrode layer.
7. The method according to claim 1 , wherein the heat treatment is performed at a temperature higher than or equal to 200° C. and lower than or equal to 600° C.
8. The method according to claim 1 , comprising the step of forming a gate electrode layer over the oxide semiconductor film.
9. A method for manufacturing a semiconductor device, the method comprising the steps of:
forming an insulating film;
performing a sputtering treatment on the insulating film;
after performing the sputtering treatment, forming an oxide semiconductor film over the insulating film; and
performing a heat treatment on the oxide semiconductor film,
wherein the sputtering treatment is performed in an atmosphere comprising oxygen, and
wherein the oxide semiconductor film comprises indium and zinc.
10. The method according to claim 9 , comprising the step of:
forming a source electrode layer and a drain electrode layer over the insulating film,
wherein the sputtering treatment is performed on the source electrode layer and the drain electrode layer, and
wherein the oxide semiconductor film is formed over the source electrode layer and the drain electrode layer.
11. The method according to claim 9 , wherein the oxide semiconductor film is formed without exposure to air after the sputtering treatment is performed.
12. The method according to claim 9 , wherein the oxide semiconductor film comprises gallium.
13. The method according to claim 9 , wherein the atmosphere comprises an inert gas.
14. The method according to claim 9 , the method comprising the step of forming a gate electrode layer,
wherein the insulating film is formed over the gate electrode layer, and
wherein the oxide semiconductor film is formed to overlap the gate electrode layer.
15. The method according to claim 9 , wherein the heat treatment is performed at a temperature higher than or equal to 200° C. and lower than or equal to 600° C.
16. The method according to claim 9 , comprising the step of forming a gate electrode layer over the oxide semiconductor film.
17. A method for manufacturing a semiconductor device, the method comprising the steps of:
forming an insulating film;
performing a plasma treatment on the insulating film;
after performing the plasma treatment, forming an oxide semiconductor film over the insulating film; and
performing a heat treatment on the oxide semiconductor film,
wherein the plasma treatment is performed in an atmosphere comprising oxygen,
wherein the oxide semiconductor film comprises indium and zinc, and
wherein the oxide semiconductor film after performing the heat treatment has crystallinity and exhibits a peak in a range of 30°≦2θ≦35° when the oxide semiconductor film is measured by an X-ray diffraction method.
18. The method according to claim 17 , comprising the step of:
forming a source electrode layer and a drain electrode layer over the insulating film,
wherein the plasma treatment is performed on the source electrode layer and the drain electrode layer, and
wherein the oxide semiconductor film is formed over the source electrode layer and the drain electrode layer.
19. The method according to claim 17 , wherein the oxide semiconductor film is formed without exposure to air after the plasma treatment is performed.
20. The method according to claim 17 , wherein the oxide semiconductor film comprises gallium.
21. The method according to claim 17 , wherein the atmosphere comprises an inert gas.
22. The method according to claim 17 , the method comprising the step of forming a gate electrode layer,
wherein the insulating film is formed over the gate electrode layer, and
wherein the oxide semiconductor film is formed to overlap the gate electrode layer.
23. The method according to claim 17 , wherein the heat treatment is performed at a temperature higher than or equal to 700° C.
24. The method according to claim 17 , comprising the step of forming a gate electrode layer over the oxide semiconductor film.