SEMICONDUCTOR DEVICE
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 . (canceled)
2 . 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; and
a gate electrode over the second metal oxide film,
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 2 , wherein each of the first metal oxide film and the second metal oxide film comprises a constituent element of the oxide semiconductor film.
4 . The semiconductor device according to claim 2 , wherein each of the first metal oxide film and the second metal oxide film comprises gallium.
5 . The semiconductor device according to claim 2 , wherein a proportion of a constituent element of the first metal oxide film is equal to a proportion of a constituent element of the second metal oxide film.
6 . The semiconductor device according to claim 2 , 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.
7 . The semiconductor device according to claim 2 , wherein a side surface of the oxide semiconductor film is in contact with the second metal oxide film in a channel width direction.
8 . The semiconductor device according to claim 2 , wherein the first metal oxide film is in contact with the second metal oxide film in a channel width direction.
9 . A semiconductor device comprising:
a first metal oxide film over a substrate;
an oxide semiconductor film in contact with the first metal oxide film;
source and drain electrodes in contact with the oxide semiconductor film;
a second metal oxide film in contact with the oxide semiconductor film;
a gate insulating film over the second metal oxide film; and
a gate electrode over the gate insulating film,
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.
10 . The semiconductor device according to claim 9 , wherein each of the first metal oxide film and the second metal oxide film comprises a constituent element of the oxide semiconductor film.
11 . The semiconductor device according to claim 9 , wherein each of the first metal oxide film and the second metal oxide film comprises gallium.
12 . The semiconductor device according to claim 9 , wherein a proportion of a constituent element of the first metal oxide film is equal to a proportion of a constituent element of the second metal oxide film.
13 . The semiconductor device according to claim 9 , 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.
14 . The semiconductor device according to claim 9 , wherein a side surface of the oxide semiconductor film is in contact with the second metal oxide film in a channel width direction.
15 . The semiconductor device according to claim 9 , wherein the first metal oxide film is in contact with the second metal oxide film in a channel width direction.