Patent ID: 8633480

Claim:
A semiconductor device comprising: a pixel portion including a first transistor over a substrate; a driver circuit portion including a second transistor over the substrate, wherein the first transistor comprises: a first gate electrode layer over the substrate; a first insulating layer over the first gate electrode layer; a first oxide semiconductor layer over the first insulating layer, the first oxide semiconductor layer including a first crystalline region in a superficial portion of the first oxide semiconductor layer; a first source electrode layer overlapping with part of the first oxide semiconductor layer; a first drain electrode layer overlapping with part of the first oxide semiconductor layer; and a second insulating layer over the first source electrode layer and the first drain electrode layer and in contact with part of the first oxide semiconductor layer, wherein the second transistor comprises: a second oxide semiconductor layer over the first insulating layer, the second oxide semiconductor layer including a second crystalline region in a superficial portion of the second oxide semiconductor layer; a second source electrode layer overlapping with part of the second oxide semiconductor layer; a second drain electrode layer overlapping with part of the second oxide semiconductor layer; the second insulating layer over the second source electrode layer and the second drain electrode layer and in contact with part of the second oxide semiconductor layer; and a second gate electrode layer over the second oxide semiconductor layer with the second insulating layer interposed therebetween, wherein the superficial portion of the first oxide semiconductor layer is located on a side opposite to a channel formation region of the first oxide semiconductor layer, and wherein each of the first gate electrode layer, the first source electrode layer, and the first drain electrode layer is a conductive layer having a light transmitting property.