Transistor having two metal oxide films and an oxide semiconductor film
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 over and in contact with the first metal oxide film;
source and drain electrodes in contact with the oxide semiconductor film;
a second metal oxide film over and in contact with the oxide semiconductor film;
a first insulating film over and in contact with the second metal oxide film; and
a gate electrode over the first insulating film,
wherein the oxide semiconductor film is surrounded by the first metal oxide film and the second metal oxide film in a channel width direction, and
wherein the source and drain electrodes are provided between the oxide semiconductor film and the second metal oxide film.
2. The semiconductor device according to claim 1 , wherein each of the first metal oxide film and the second metal oxide film contains gallium.
3. The semiconductor device according to claim 1 , wherein each of the first metal oxide film and the second metal oxide film has a larger energy gap than the oxide semiconductor film.
4. 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.
5. The semiconductor device according to claim 1 , wherein each of the first metal oxide film and the second metal oxide film is an i-type film.
6. The semiconductor device according to claim 1 , wherein edge portions of the oxide semiconductor film are positioned on an inner side of edge portions of the gate electrode in the channel width direction.
7. A semiconductor device comprising:
a first metal oxide film over a substrate;
an oxide semiconductor film over and in contact with the first metal oxide film;
source and drain electrodes in contact with the oxide semiconductor film;
a second metal oxide film over and in contact with the oxide semiconductor film;
a first insulating film over and in contact with the second metal oxide film; and
a gate electrode over the first insulating film,
wherein the oxide semiconductor film is surrounded by the first metal oxide film and the second metal oxide film in a channel width direction,
wherein each of the first metal oxide film and the second metal oxide film contains a constituent element of the oxide semiconductor film, and
wherein the source and drain electrodes are provided between the oxide semiconductor film and the second metal oxide film.
8. The semiconductor device according to claim 7 , wherein each of the first metal oxide film and the second metal oxide film contains gallium.
9. The semiconductor device according to claim 7 , wherein each of the first metal oxide film and the second metal oxide film has a larger energy gap than the oxide semiconductor film.
10. The semiconductor device according to claim 7 , 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.
11. The semiconductor device according to claim 7 , wherein each of the first metal oxide film and the second metal oxide film is an i-type film.
12. The semiconductor device according to claim 7 , wherein edge portions of the oxide semiconductor film are positioned on an inner side of edge portions of the gate electrode in the channel width direction.
13. A semiconductor device comprising:
a second insulating film over a substrate;
a first metal oxide film over and in contact with the second insulating film;
an oxide semiconductor film over and in contact with the first metal oxide film;
source and drain electrodes in contact with the oxide semiconductor film;
a second metal oxide film over and in contact with the oxide semiconductor film;
a first insulating film over and in contact with the second metal oxide film; and
a gate electrode over the first insulating film,
wherein the oxide semiconductor film is surrounded by the first metal oxide film and the second metal oxide film in a channel width direction,
wherein each of the first metal oxide film and the second metal oxide film contains a constituent element of the oxide semiconductor film,
wherein the second insulating film contains aluminum oxide, and
wherein the source and drain electrodes are provided between the oxide semiconductor film and the second metal oxide film.
14. The semiconductor device according to claim 13 , wherein each of the first metal oxide film and the second metal oxide film contains gallium.
15. The semiconductor device according to claim 13 , wherein each of the first metal oxide film and the second metal oxide film has a larger energy gap than the oxide semiconductor film.
16. The semiconductor device according to claim 13 , 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.
17. The semiconductor device according to claim 13 , wherein each of the first metal oxide film and the second metal oxide film is an i-type film.
18. The semiconductor device according to claim 13 , wherein edge portions of the oxide semiconductor film are positioned on an inner side of edge portions of the gate electrode in the channel width direction.
19. A semiconductor device comprising:
a second insulating film over a substrates;
a first metal oxide film over and in contact with the second insulating film;
an oxide semiconductor film over and in contact with the first metal oxide film;
source and drain electrodes in contact with the oxide semiconductor film;
a second metal oxide film over and in contact with the oxide semiconductor film; and
a first insulating film over the second metal oxide film,
wherein the oxide semiconductor film is surrounded by the first metal oxide film and the second metal oxide film in a channel width direction,
wherein each of the first metal oxide film and the second metal oxide film contains a constituent element of the oxide semiconductor film,
wherein each of the first insulating film and the second insulating film contains aluminum oxide, and
wherein the source and drain electrodes are provided between the oxide semiconductor film and the second metal oxide film.
20. The semiconductor device according to claim 19 , wherein each of the first metal oxide film and the second metal oxide film contains gallium.
21. The semiconductor device according to claim 19 , wherein each of the first metal oxide film and the second metal oxide film has a larger energy gap than the oxide semiconductor film.
22. The semiconductor device according to claim 19 , 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.
23. The semiconductor device according to claim 19 , wherein each of the first metal oxide film and the second metal oxide film is an i-type film.
24. The semiconductor device according to claim 19 , further comprising a gate electrode over the first insulating film,
wherein edge portions of the oxide semiconductor film are positioned on an inner side of edge portions of the gate electrode in the channel width direction.
25. The semiconductor device according to claim 19 , further comprising a gate electrode over the first insulating film.