Semiconductor device comprising an oxide semiconductor film

1. A semiconductor device comprising:

an oxide semiconductor film comprising a channel formation region;

a gate electrode over the oxide semiconductor film with a first insulating film interposed therebetween, the gate electrode comprising a region overlapping with the channel formation region; and

a source electrode and a drain electrode electrically connected to the oxide semiconductor film,

wherein each of a top surface of the gate electrode, a top surface of the source electrode, and a top surface of the drain electrode comprises a region in contact with a second insulating film,

wherein a top surface of the first insulating film comprises a region in direct contact with the gate electrode and a region in direct contact with the second insulating film and protruding from a side surface of the gate electrode along a channel length direction of the oxide semiconductor film in a cross-sectional view parallel to the channel length direction of the oxide semiconductor film, and

wherein the oxide semiconductor film comprises a region in contact with the first insulating film and a region in contact with the second insulating film and adjacent to the region in contact with the first insulating film in the cross-sectional view.

2. The semiconductor device according to claim 1 ,

wherein the source electrode and the drain electrode are provided in a same layer as the gate electrode.

3. The semiconductor device according to claim 1 ,

wherein a thickness of each of the gate electrode, the source electrode, and the drain electrode is greater than or equal to 30 nm and less than or equal to 500 nm.

4. The semiconductor device according to claim 1 ,

wherein the oxide semiconductor film comprises In, Ga, and Zn.

5. The semiconductor device according to claim 1 ,

wherein the first insulating film comprises a silicon oxide.

6. The semiconductor device according to claim 1 ,

wherein a width of each of the source electrode and the drain electrode is larger than a width of the oxide semiconductor film in a cross-sectional view parallel to a channel width direction of the oxide semiconductor film.

7. A semiconductor device comprising:

an oxide semiconductor film comprising a channel formation region;

a gate electrode over the oxide semiconductor film with a first insulating film interposed therebetween, the gate electrode comprising a region overlapping with the channel formation region; and

a source electrode and a drain electrode electrically connected to the oxide semiconductor film,

wherein the source electrode, the drain electrode, and the gate electrode comprises a same stacked-layer structure,

wherein each of a top surface of the gate electrode, a top surface of the source electrode, and a top surface of the drain electrode comprises a region in contact with a second insulating film,

wherein a top surface of the first insulating film comprises a region in direct contact with the gate electrode and a region in direct contact with the second insulating film and protruding from a side surface of the gate electrode along a channel length direction of the oxide semiconductor film in a cross-sectional view parallel to the channel length direction of the oxide semiconductor film, and

wherein the oxide semiconductor film comprises a region in contact with the first insulating film and a region in contact with the second insulating film and adjacent to the region in contact with the first insulating film in the cross-sectional view.

8. The semiconductor device according to claim 7 ,

wherein a stacked-layer structure of the source electrode, a stacked-layer structure of the drain electrode, and a stacked-layer structure of the gate electrode comprise a same material.

9. The semiconductor device according to claim 7 ,

wherein a thickness of a stacked-layer structure of each of the source electrode and the drain electrode is substantially the same as a thickness of a stacked-layer structure of the gate electrode.

10. The semiconductor device according to claim 7 ,

wherein a thickness of each of the gate electrode, the source electrode, and the drain electrode is greater than or equal to 30 nm and less than or equal to 500 nm.

11. The semiconductor device according to claim 7 ,

wherein the oxide semiconductor film comprises In, Ga, and Zn.

12. The semiconductor device according to claim 7 ,

wherein the first insulating film comprises a silicon oxide.

13. The semiconductor device according to claim 7 ,

wherein a width of each of the source electrode and the drain electrode is larger than a width of the oxide semiconductor film in a cross-sectional view parallel to a channel width direction of the oxide semiconductor film.

14. A semiconductor device comprising:

an oxide semiconductor film comprising a channel formation region; and

a gate electrode, a source electrode, and a drain electrode formed by patterning a conductive film,

wherein the gate electrode is provided over the oxide semiconductor film with a first insulating film interposed therebetween,

wherein the gate electrode comprises a region overlapping with the channel formation region,

wherein the source electrode and the drain electrode are electrically connected to the oxide semiconductor film,

wherein each of a top surface of the gate electrode, a top surface of the source electrode, and a top surface of the drain electrode comprises a region in contact with a second insulating film,

wherein a top surface of the first insulating film comprises a region in direct contact with the gate electrode and a region in direct contact with the second insulating film and protruding from a side surface of the gate electrode along a channel length direction of the oxide semiconductor film in a cross-sectional view parallel to the channel length direction of the oxide semiconductor film, and

wherein the oxide semiconductor film comprises a region in contact with the first insulating film and a region in contact with the second insulating film and adjacent to the region in contact with the first insulating film in the cross-sectional view.

15. The semiconductor device according to claim 14 ,

wherein a thickness of each of the gate electrode, the source electrode, and the drain electrode is greater than or equal to 30 nm and less than or equal to 500 nm.

16. The semiconductor device according to claim 14 ,

wherein the oxide semiconductor film comprises In, Ga, and Zn.

17. The semiconductor device according to claim 14 ,

wherein the first insulating film comprises a silicon oxide.

18. The semiconductor device according to claim 14 ,

wherein a width of each of the source electrode and the drain electrode is larger than a width of the oxide semiconductor film in a cross-sectional view parallel to a channel width direction of the oxide semiconductor film.

19. A semiconductor device comprising:

a driver circuit portion comprising a first transistor, the first transistor comprising:

a first gate electrode;

a first insulating film over the first gate electrode;

a first oxide semiconductor film over the first insulating film, the first oxide semiconductor film comprising a first channel formation region;

a source electrode and a drain electrode electrically connected to the first oxide semiconductor film;

a second insulating film over the first oxide semiconductor film;

a second gate electrode over the second insulating film; and

a third insulating film over the second gate electrode; and

a pixel portion comprising a second transistor, the second transistor comprising a second oxide semiconductor film comprising a second channel formation region,

wherein the first transistor has a dual-gate structure,

wherein the second transistor has a top-gate structure,

wherein each of a top surface of the second gate electrode, a top surface of the source electrode, and a top surface of the drain electrode comprises a region in direct contact with the third insulating film,

wherein a top surface of the second insulating film comprises a region in direct contact with the second gate electrode and a region in direct contact with the third insulating film and protruding from a side surface of the second gate electrode in a direction parallel to a channel length direction of the first oxide semiconductor film,

wherein the first oxide semiconductor film comprises a region in direct contact with the second insulating film and a region in direct contact with the third insulating film and adjacent to the region in direct contact with the second insulating film, and

wherein a width of at least one of the source electrode and the drain electrode is larger than a width of the first oxide semiconductor film in a direction parallel to a channel width direction of the first oxide semiconductor film.

20. The semiconductor device according to claim 19 ,

wherein each of the first oxide semiconductor film and the second oxide semiconductor film comprises In, Ga, and Zn.

21. The semiconductor device according to claim 19 ,

wherein the second insulating film comprises a silicon oxide.

22. A semiconductor device comprising:

a driver circuit portion comprising a first transistor, the first transistor comprising:

a first gate electrode;

a first insulating film over the first gate electrode;

a first oxide semiconductor film over the first insulating film, the first oxide semiconductor film comprising a first channel formation region;

a source electrode and a drain electrode electrically connected to the first oxide semiconductor film;

a second insulating film over the first oxide semiconductor film;

a second gate electrode over the second insulating film; and

a third insulating film over the second gate electrode; and

a pixel portion comprising a second transistor, the second transistor comprising a second oxide semiconductor film comprising a second channel formation region,

wherein the second transistor does not comprise a gate electrode under the second oxide semiconductor film,

wherein each of a top surface of the second gate electrode, a top surface of the source electrode, and a top surface of the drain electrode comprises a region in direct contact with the third insulating film,

wherein a top surface of the second insulating film comprises a region in direct contact with the second gate electrode and a region in direct contact with the third insulating film and protruding from a side surface of the second gate electrode in a direction parallel to a channel length direction of the first oxide semiconductor film,

wherein the first oxide semiconductor film comprises a region in direct contact with the second insulating film and a region in direct contact with the third insulating film and adjacent to the region in direct contact with the second insulating film, and

wherein a width of at least one of the source electrode and the drain electrode is larger than a width of the first oxide semiconductor film in a direction parallel to a channel width direction of the first oxide semiconductor film.

23. The semiconductor device according to claim 22 ,

wherein each of the first oxide semiconductor film and the second oxide semiconductor film comprises In, Ga, and Zn.

24. The semiconductor device according to claim 22 ,

wherein the second insulating film comprises a silicon oxide.