Patent ID: 8030651

Claim:
A micro electro mechanical device comprising: a micro structure formed over a substrate having an insulating surface, the micro structure including a first structural layer movable with respect to the substrate and a second structural layer which is partially fixed to the substrate; and an electric circuit including a transistor electrically connected to the micro structure and formed over the substrate, wherein the transistor includes a gate insulating layer, a first semiconductor layer in which a channel formation region is formed, and a second semiconductor layer in which an impurity region is formed, wherein each of the first structural layer and the second structural layer includes an insulating layer, a third semiconductor layer which is in contact with the insulating layer, and a fourth semiconductor layer which is in contact with the third semiconductor layer, wherein the gate insulating layer and the insulating layer of each of the first structural layer and the second structural layer are patterned portions of a same insulating film formed over the substrate, wherein the first semiconductor layer and the third semiconductor layer are patterned portions of a same semiconductor film formed over the substrate, and wherein the second semiconductor layer and the fourth semiconductor layer are patterned portions of a same semiconductor film formed over the substrate.