Semiconductor device and method for manufacturing semiconductor device
Provided is a semiconductor device in which a deterioration in electrical characteristics which becomes more noticeable as miniaturization can be suppressed. The semiconductor device includes a first oxide semiconductor film over an insulating surface; a second oxide semiconductor film over the first oxide semiconductor film; a source electrode and a drain electrode in contact with each side surface of the first oxide semiconductor film and the second oxide semiconductor film; a first insulating film and a second insulating film over the source electrode and the drain electrode; a third oxide semiconductor film over the second oxide semiconductor film, the source electrode, and the drain electrode; a gate insulating film over the third oxide semiconductor film; and a gate electrode in contact with an upper surface of the gate insulating film and facing an upper surface and the side surface of the second oxide semiconductor film.
1. A semiconductor device comprising:
a first insulating film;
a first oxide semiconductor film over the first insulating film;
a second oxide semiconductor film over the first oxide semiconductor film;
a first conductive film and a second conductive film over the first insulating film;
a third oxide semiconductor film over the second oxide semiconductor film, the first conductive film, and the second conductive film;
a second insulating film over the third oxide semiconductor film; and
a third conductive film over the second insulating film,
wherein each of the first conductive film and the second conductive film is in contact with a first side surface of the second oxide semiconductor film,
wherein, in a channel width direction, the third conductive film faces a second side surface of the second oxide semiconductor film,
wherein the first oxide semiconductor film comprises a depressed portion, and
wherein the third oxide semiconductor film is in contact with the depressed portion.
2. The semiconductor device according to claim 1 , wherein, in the channel width direction, the third oxide semiconductor film is in contact with the second side surface of the second oxide semiconductor film.
3. The semiconductor device according to claim 1 , wherein an entire upper surface of the second oxide semiconductor film is in contact with the third oxide semiconductor film.
4. The semiconductor device according to claim 1 , wherein, in a channel length direction, a length of the third oxide semiconductor film is larger than a length of each of the first oxide semiconductor film and the second oxide semiconductor film.
5. The semiconductor device according to claim 1 , wherein the third oxide semiconductor film comprises indium, gallium, and zinc.
6. A semiconductor device comprising:
a first conductive film;
a first insulating film over the first conductive film;
a first oxide semiconductor film over the first insulating film;
a second oxide semiconductor film over the first oxide semiconductor film;
a second conductive film and a third conductive film over the first insulating film;
a third oxide semiconductor film over the second oxide semiconductor film, the first conductive film, and the second conductive film;
a second insulating film over the third oxide semiconductor film; and
a fourth conductive film over the second insulating film,
wherein each of the second conductive film and the third conductive film is in contact with a first side surface of the second oxide semiconductor film,
wherein, in a channel width direction, the fourth conductive film faces a second side surface of the second oxide semiconductor film,
wherein the first oxide semiconductor film comprises a depressed portion, and
wherein the third oxide semiconductor film is in contact with the depressed portion.
7. The semiconductor device according to claim 6 , wherein, in the channel width direction, the third oxide semiconductor film is in contact with the second side surface of the second oxide semiconductor film.
8. The semiconductor device according to claim 6 , wherein an entire upper surface of the second oxide semiconductor film is in contact with the third oxide semiconductor film.
9. The semiconductor device according to claim 6 , wherein, in a channel length direction, a length of the third oxide semiconductor film is larger than a length of each of the first oxide semiconductor film and the second oxide semiconductor film.
10. The semiconductor device according to claim 6 , wherein the fourth conductive film is electrically connected to the first conductive film.
11. The semiconductor device according to claim 6 , wherein the third oxide semiconductor film comprises indium, gallium, and zinc.