Patent ID: 8729550

Claim:
A semiconductor device comprising: a pixel portion including a first transistor and a pixel electrode over a substrate; and a driver circuit including a second transistor over the substrate, wherein the first transistor comprises: a first gate electrode over the substrate; a gate insulating layer over the first gate electrode; a first oxide semiconductor layer over the gate insulating layer; a first channel protective layer over and in contact with a part of the first oxide semiconductor layer; and a first source electrode and a first drain electrode over the first channel protective layer and the first oxide semiconductor layer, wherein the second transistor comprises: a second gate electrode over the substrate; the gate insulating layer over the second gate electrode; a second oxide semiconductor layer over the gate insulating layer; a second channel protective layer over and in contact with a part of the second oxide semiconductor layer; a second source electrode and a second drain electrode over the second channel protective layer and the second oxide semiconductor layer; and a third gate electrode over the second channel protective layer, wherein the third gate electrode overlaps with the second gate electrode, wherein the pixel electrode is electrically connected to one of the first source electrode and the first drain electrode, and wherein the third gate electrode and the pixel electrode are provided on a same surface.