Patent ID: 8232598

Claim:
A display device comprising: a plurality of pixels over a substrate comprising an insulating surface, comprising: a first field-effect transistor comprising a first semiconductor layer, including silicon, a first gate insulating layer, a first gate electrode layer, a first source electrode layer, and a first drain electrode layer; a planarization layer over the first field-effect transistor; a second field-effect transistor comprising a second semiconductor layer, a second gate insulating layer, a second gate electrode layer, a second source electrode layer, and a second drain electrode layer, over the planarization layer; and a wiring over the first semiconductor layer, wherein the first semiconductor layer and the second semiconductor layer are not overlapped with each other, wherein the first field-effect transistor is provided over the substrate comprising the insulating surface by being bonded to a first insulating layer which is formed between the first semiconductor layer and the substrate comprising the insulating surface, wherein the second field-effect transistor is provided over the first field-effect transistor by being bonded to a second insulating layer which is provided over the planarization layer, and wherein the wiring penetrates the first gate insulating layer, the planarization layer and the second gate insulating layer, and reaches the second semiconductor layer.