Semiconductor device comprising an oxide semiconductor film

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.

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.

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.

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.