Semiconductor device having metal oxide layer with tapered side surface
A semiconductor device includes a substrate, an oxide semiconductor layer over the substrate, a gate insulating layer over the oxide semiconductor layer, a metal oxide layer over the gate insulating layer, and a gate electrode over the metal oxide layer. A first side surface of the metal oxide protrudes from a second side surface of the gate electrode in a plan view.
1. A semiconductor device comprising:
a substrate;
an oxide semiconductor layer over the substrate;
a gate insulating layer over the oxide semiconductor layer;
a metal oxide layer over the gate insulating layer; and
a gate electrode over the metal oxide layer,
wherein a first side surface of the metal oxide protrudes from a second side surface of the gate electrode in a plan view, and
wherein a first taper angle between the first side surface and a lower surface of the metal oxide layer is smaller than a second taper angle between the second side surface and a lower surface of the gate electrode.
2. The semiconductor device according to claim 1 , wherein the first taper angle is greater than or equal to 30 degrees and less than or equal to 70 degrees.
3. The semiconductor device according to claim 1 , wherein a thickness of the metal oxide layer is greater than or equal to 10 nm and less than or equal to 100 nm.
4. The semiconductor device according to claim 1 , wherein the metal oxide layer comprises indium.
5. The semiconductor device according to claim 1 ,
wherein the gate electrode comprises:
a first metal layer in contact with the metal oxide layer; and
a second metal layer over the first metal layer, and
the second metal layer comprises aluminum.
6. The semiconductor device according to claim 5 , wherein the first metal layer comprises molybdenum.
7. The semiconductor device according to claim 1 , wherein a side surface of the oxide semiconductor layer is covered with the gate insulating layer.
8. The semiconductor device according to claim 1 , wherein the substrate is a flexible substrate.