US Patent 8420441 Method for manufacturing oxide semiconductor device

One object is to provide a semiconductor device with a structure which enables reduction in parasitic capacitance sufficiently between wirings. In a bottom-gate type thin film transistor including a stacked layer of a first layer which is a metal thin film oxidized partly or entirely and an oxide semiconductor layer, the following oxide insulating layers are formed together: an oxide insulating layer serving as a channel protective layer which is over and in contact with a part of the oxide semiconductor layer overlapping with a gate electrode layer; and an oxide insulating layer which covers a peripheral portion and a side surface of the stacked oxide semiconductor layer.