Semiconductor device
View Patent ↗An object is to provide a semiconductor device using an oxide semiconductor having stable electric characteristics and high reliability. A transistor including the oxide semiconductor film in which a top surface portion of the oxide semiconductor film is provided with a metal oxide film containing a constituent similar to that of the oxide semiconductor film and functioning as a channel protective film is provided. In addition, the oxide semiconductor film used for an active layer of the transistor is an oxide semiconductor film highly purified to be electrically i-type (intrinsic) by heat treatment in which impurities such as hydrogen, moisture, a hydroxyl group, or a hydride are removed from the oxide semiconductor and oxygen which is a major constituent of the oxide semiconductor and is reduced concurrently with a step of removing impurities is supplied.
1. A semiconductor device comprising:
a gate electrode;
a gate insulating film over the gate electrode;
an oxide semiconductor film over the gate insulating film;
a metal oxide film over the oxide semiconductor film; and
a source electrode over the metal oxide film,
a drain electrode over the metal oxide film,
wherein the source electrode is in contact with the oxide semiconductor film,
wherein the drain electrode is in contact with the oxide semiconductor film,
wherein the metal oxide film contains at least one of metal elements selected from constituent elements of the oxide semiconductor film, and
wherein the source electrode and the drain electrode are in contact with the oxide semiconductor film through openings of the metal oxide film.
2. A semiconductor device according to claim 1 , further comprising:
an insulating film over the metal oxide film, the source electrode, and the drain electrode; and
a conductive film over the insulating film.
3. The semiconductor device according to claim 1 , wherein the oxide semiconductor film does not extend beyond the gate electrode.
4. The semiconductor device according to claim 1 , further comprising a protective insulating film over the metal oxide film,
wherein the source electrode and the drain electrode are formed over the protective insulating film.
5. The semiconductor device according to claim 1 , wherein the metal oxide film has a larger energy gap than the oxide semiconductor film.
6. The semiconductor device according to claim 1 , wherein an energy at a bottom of a conduction band of the metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.
7. The semiconductor device according to claim 1 , wherein the metal oxide film contains a gallium oxide.
8. The semiconductor device according to claim 1 , wherein the gate insulating film contains a silicon oxide or a hafnium oxide.
9. The semiconductor device according to claim 1 ,
wherein the source electrode is in contact with the metal oxide film, and
wherein the drain electrode is in contact with the metal oxide film.
10. A semiconductor device comprising:
a gate electrode;
a gate insulating film over the gate electrode;
a first metal oxide film over the gate insulating film;
an oxide semiconductor film over the first metal oxide film;
a second metal oxide film over the oxide semiconductor film; and
a source electrode and a drain electrode over the second metal oxide film,
wherein the source electrode and the drain electrode are in contact with the oxide semiconductor film, and
wherein at least one of the first metal oxide film and the second metal oxide film contains at least one of metal elements selected from constituent elements of the oxide semiconductor film.
11. The semiconductor device according to claim 10 , wherein the source electrode and the drain electrode are in contact with the oxide semiconductor film through openings of the second metal oxide film.
12. The semiconductor device according to claim 10 , wherein at least one of the first metal oxide film and the second metal oxide film has a larger energy gap than the oxide semiconductor film.
13. The semiconductor device according to claim 10 , wherein at least one of an energy at a bottom of a conduction band of the first metal oxide film and an energy at a bottom of a conduction band of the second metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.
14. The semiconductor device according to claim 10 , wherein at least one of the first metal oxide film and the second metal oxide film contains a gallium oxide.
15. The semiconductor device according to claim 10 , wherein the gate insulating film contains a silicon oxide or a hafnium oxide.
16. A semiconductor device comprising:
an oxide semiconductor film;
a metal oxide film over the oxide semiconductor film;
a source electrode and a drain electrode over the metal oxide film;
an insulating film over the metal oxide film, the source electrode, and the drain electrode; and
a conductive film over the insulating film,
wherein the source electrode and the drain electrode are in contact with the oxide semiconductor film,
wherein the metal oxide film contains at least one of metal elements selected from constituent elements of the oxide semiconductor film, and
wherein the source electrode and the drain electrode are in contact with the oxide semiconductor film through openings of the metal oxide film.
17. The semiconductor device according to claim 16 , wherein the metal oxide film has a larger energy gap than the oxide semiconductor film.
18. The semiconductor device according to claim 16 , wherein an energy at a bottom of a conduction band of the metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.
19. The semiconductor device according to claim 16 , wherein the metal oxide film contains a gallium oxide.
20. A semiconductor device comprising:
a gate electrode;
a gate insulating film over the gate electrode;
an oxide semiconductor film over the gate insulating film;
an oxide film over the oxide semiconductor film; and
a source electrode over the oxide film,
a drain electrode over the oxide film,
wherein the source electrode is in contact with the oxide semiconductor film,
wherein the drain electrode is in contact with the oxide semiconductor film,
wherein the oxide film contains a constituent element of the oxide semiconductor film, and
wherein the source electrode and the drain electrode are in contact with the oxide semiconductor film through openings of the oxide film.
21. A semiconductor device according to claim 20 , further comprising:
an insulating film over the oxide film, the source electrode, and the drain electrode; and
a conductive film over the insulating film.
22. The semiconductor device according to claim 20 , further comprising a protective insulating film over the oxide film,
wherein the source electrode and the drain electrode are formed over the protective insulating film.
23. The semiconductor device according to claim 20 , wherein the oxide film contains a gallium oxide.
24. The semiconductor device according to claim 20 , wherein the gate insulating film contains a silicon oxide or a hafnium oxide.