Patent ID: 8829586

Claim:
A semiconductor device comprising: a base insulating layer over a substrate; a transistor over the base insulating layer, the transistor comprising: an oxide semiconductor layer over the base insulating layer, the oxide semiconductor layer comprising a channel formation region, wherein the channel formation region comprises indium and oxygen; a source electrode and a drain electrode in contact with the oxide semiconductor layer; a first gate insulating layer over and in contact with the oxide semiconductor layer; a second gate insulating layer over the first gate insulating layer; and a gate electrode overlapping with the oxide semiconductor layer over the second gate insulating layer; and a capacitor comprising: a first electrode; a portion of the oxide semiconductor layer over the first electrode; a dielectric layer over the portion of the oxide semiconductor layer over the first electrode; a second electrode over the dielectric layer, wherein the first electrode and the second electrode overlap each other with the dielectric layer and the portion of the oxide semiconductor layer interposed therebetween, wherein the second gate insulating layer has higher relative permittivity than the first gate insulating layer.