Display device and method for manufacturing the same

A semiconductor device comprising:

• a semiconductor layer comprising a channel formation region of a first transistor;
• a first conductive layer;
• a second conductive layer;
• a first insulating layer between the first conductive layer and the semiconductor layer;
• an oxide semiconductor layer comprising a channel formation region of a second transistor;
• a third conductive layer in contact with the oxide semiconductor layer;
• a fourth conductive layer in contact with the first insulating layer;
• and
• a second insulating layer in contact with the oxide semiconductor layer,
• wherein the channel formation region of the first transistor, the first conductive layer, and the second conductive layer overlap with one another,
• wherein the oxide semiconductor layer and the fourth conductive layer overlap with each other,
• wherein the first conductive layer comprises a region configured to serve as a gate electrode of the first transistor,
• wherein the first insulating layer comprises a region configured to serve as a gate insulating film of the first transistor,
• wherein the third conductive layer comprises a region configured to serve as one of a source electrode and a drain electrode of the second transistor,
• wherein the second insulating layer and the third conductive layer overlap with each other, and
• wherein the second insulating layer is not provided between the semiconductor layer and the second conductive layer.

A semiconductor device comprising:

• a semiconductor layer comprising a channel formation region of a first transistor;
• a first conductive layer;
• a second conductive layer;
• a first insulating layer between the first conductive layer and the semiconductor layer;
• an oxide semiconductor layer comprising a channel formation region of a second transistor;
• a third conductive layer in contact with the oxide semiconductor layer;
• a fourth conductive layer in contact with the first insulating layer;
• a second insulating layer in contact with the oxide semiconductor layer;
• and
• a fifth conductive layer in contact with the second insulating layer,
• wherein the fifth conductive layer comprises a region configured to serve as one electrode of a capacitor,
• wherein the channel formation region of the first transistor, the first conductive layer, and the second conductive layer overlap with one another,
• wherein the oxide semiconductor layer and the fourth conductive layer overlap with each other,
• wherein the first conductive layer comprises a region configured to serve as a gate electrode of the first transistor,
• wherein the first insulating layer comprises a region configured to serve as a gate insulating film of the first transistor,
• wherein the third conductive layer comprises a region configured to serve as one of a source electrode and a drain electrode of the second transistor,
• wherein the second insulating layer and the third conductive layer overlap with each other, and
• wherein the second insulating layer is not provided between the semiconductor layer and the second conductive layer.