Semiconductor device

A semiconductor device comprising:

• an oxide semiconductor layer provided over a substrate comprising an insulating surface;
• a first conductive layer provided partly over the oxide semiconductor layer;
• a second conductive layer provided partly over the first conductive layer;
• an insulating layer provided over the second conductive layer;
• a gate insulating layer provided over the oxide semiconductor layer, the first conductive layer, the second conductive layer, and the insulating layer;
• and
• a gate electrode layer provided over the oxide semiconductor layer with the gate insulating layer provided therebetween,
• wherein the gate electrode layer is overlapped with the first conductive layer with the gate insulating layer provided therebetween, and is not overlapped with the second conductive layer with the gate insulating layer provided therebetween.

A semiconductor device comprising:

• an oxide semiconductor layer provided over a substrate comprising an insulating surface;
• a first conductive layer provided partly over the oxide semiconductor layer;
• an insulating layer provided partly over the first conductive layer;
• a second conductive layer provided partly over the insulating layer and is in contact with the first conductive layer in an opening in the insulating layer;
• a gate insulating layer provided over the oxide semiconductor layer, the first conductive layer, the second conductive layer, and the insulating layer;
• and
• a gate electrode layer provided over the oxide semiconductor layer with the gate insulating layer provided therebetween,
• wherein the gate electrode layer is overlapped with the first conductive layer with the gate insulating layer provided therebetween, and is not overlapped with the second conductive layer with the gate insulating layer provided therebetween.

A semiconductor device comprising:

• a substrate comprising an insulating surface;
• an insulating layer partly comprising an embedded conductive layer over the insulating surface;
• an oxide semiconductor layer over the insulating layer;
• a first conductive layer provided partly over the oxide semiconductor layer;
• a second conductive layer provided partly over the first conductive layer;
• a gate insulating layer provided over the oxide semiconductor layer, the first conductive layer, and the second conductive layer;
• and
• a gate electrode layer provided over the oxide semiconductor layer with the gate insulating layer provided therebetween,
• wherein the gate electrode layer is overlapped with the first conductive layer with the gate insulating layer provided therebetween, and is not overlapped with the second conductive layer with the gate insulating layer provided therebetween.