Patent ID: 8344374

Claim:
A semiconductor device comprising: a first insulating layer including silicon nitride; a first conductive layer over the first insulating layer; a second conductive layer over the first conductive layer; a second insulating layer including silicon nitride over the first conductive layer and the second conductive layer; a third insulating layer including silicon oxide over the second insulating layer; an oxide semiconductor layer over the third insulating layer; a source electrode and a drain electrode, which are provided over the oxide semiconductor layer; a fourth insulating layer including silicon oxide over the source electrode, the drain electrode and the oxide semiconductor layer; a fifth insulating layer including silicon nitride over the fourth insulating layer; a third conductive layer over the fifth insulating layer and electrically connected to one of the source electrode and the drain electrode; a sixth insulating layer including silicon nitride over the third conductive layer; and a fourth conductive layer over the sixth insulating layer and electrically connected to the other one of the source electrode and the drain electrode, wherein the first conductive layer and the second conductive layer overlap with the oxide semiconductor layer.