Semiconductor device
View Patent ↗An object is to stabilize electric characteristics of a semiconductor device including an oxide semiconductor to increase reliability. The semiconductor device includes an insulating film; a first metal oxide film on and in contact with the insulating film; an oxide semiconductor film partly in contact with the first metal oxide film; source and drain electrodes electrically connected to the oxide semiconductor film; a second metal oxide film partly in contact with the oxide semiconductor film; a gate insulating film on and in contact with the second metal oxide film; and a gate electrode over the gate insulating film.
1. A semiconductor device comprising:
a first metal oxide film over a substrate;
an oxide semiconductor film in contact with the first metal oxide film;
a second metal oxide film in contact with the oxide semiconductor film;
source and drain electrodes electrically connected to the oxide semiconductor film;
a gate electrode overlapping with the oxide semiconductor film; and
a gate insulating film between the oxide semiconductor film and the gate electrode,
wherein the first metal oxide film contains gallium,
wherein the oxide semiconductor film contains indium, gallium, and zinc,
wherein the oxide semiconductor film is in contact with a side surface and a top surface of each of the source and drain electrodes, and
wherein the first metal oxide film and the second metal oxide film are in contact with each other in a region where the oxide semiconductor film does not exist.
2. The semiconductor device according to claim 1 ,
wherein an energy at a bottom of a conduction band of each of the first metal oxide film and the second metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.
3. The semiconductor device according to claim 1 ,
wherein the second metal oxide film is in contact with the top surface of each of the source and drain electrodes.
4. The semiconductor device according to claim 1 ,
wherein an energy gap of each of the first metal oxide film and the second metal oxide film is larger than an energy gap of the oxide semiconductor film.
5. The semiconductor device according to claim 1 ,
wherein a side surface of the oxide semiconductor film is in contact with the second metal oxide film in a channel width direction.
6. The semiconductor device according to claim 1 ,
wherein the first metal oxide film is in contact with the second metal oxide film in a channel width direction.
7. The semiconductor device according to claim 1 ,
wherein the oxide semiconductor film further contains tin.
8. A semiconductor device comprising:
an insulating film over a substrate, the insulating film comprising silicon nitride;
a first oxide film over the insulating film;
an oxide semiconductor film over and in contact with the first oxide film;
a second oxide film over and in contact with the oxide semiconductor film;
source and drain electrodes electrically connected to the oxide semiconductor film; and
a gate electrode over and overlapping with the oxide semiconductor film,
wherein the oxide semiconductor film contains indium, gallium, and zinc,
wherein the first oxide film and the second oxide film contain the same element,
wherein the oxide semiconductor film is in contact with a side surface and a top surface of each of the source and drain electrodes,
wherein the second oxide film is an island-shaped,
wherein the second oxide film is positioned over the first oxide film with the oxide semiconductor film therebetween, and
wherein an end portion of the second oxide film is positioned outside an end portion of the gate electrode.
9. The semiconductor device according to claim 8 ,
wherein an energy at a bottom of a conduction band of each of the first oxide film and the second oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.
10. The semiconductor device according to claim 8 ,
wherein the source and drain electrodes comprises molybdenum, and
wherein the gate electrode has a layered structure comprising titanium and aluminum.
11. The semiconductor device according to claim 8 ,
wherein the same element contained in the first oxide film and the second oxide film is gallium.