Semiconductor device including oxide semiconductor and metal oxide
View Patent ↗An object is to provide a semiconductor device including an oxide semiconductor, which has stable electrical characteristics and improved reliability. In a transistor including an oxide semiconductor film, insulating films each including a material containing a Group 13 element and oxygen are formed in contact with the oxide semiconductor film, whereby the interfaces with the oxide semiconductor film can be kept in a favorable state. Further, the insulating films each include a region where the proportion of oxygen is higher than that in the stoichiometric composition, so that oxygen is supplied to the oxide semiconductor film; thus, oxygen defects in the oxide semiconductor film can be reduced. Furthermore, the insulating films in contact with the oxide semiconductor film each have a stacked structure so that films each containing aluminum are provided over and under the oxide semiconductor film, whereby entry of water into the oxide semiconductor film can be prevented.
1. A semiconductor device comprising:
a gate electrode;
a gate insulating film covering the gate electrode and having a stacked structure including a first metal oxide film and a second metal oxide film;
an oxide semiconductor film in contact with the second metal oxide film and in a region overlapping with the gate electrode;
a source electrode and a drain electrode electrically connected to the oxide semiconductor film;
a third metal oxide film over and in contact with the oxide semiconductor film; and
a fourth metal oxide film over and in contact with the third metal oxide film,
wherein the first metal oxide film, the second metal oxide film, the third metal oxide film, and the fourth metal oxide film each contain a Group 13 element and oxygen,
wherein each of the source electrode and the drain electrode is surrounded by the second metal oxide film and the third metal oxide film in a cross-sectional view, such that the third metal oxide film contacts top and peripheral side surfaces of at least one of the source electrode and the drain electrode, and the second metal oxide film and the oxide semiconductor film contact a bottom surface of the at least one of the source electrode and the drain electrode.
2. The semiconductor device according to claim 1 , further comprising a conductive layer over the fourth metal oxide film and in a region overlapping with the oxide semiconductor film.
3. The semiconductor device according to claim 1 , wherein the second metal oxide film and the third metal oxide film are at least partly in contact with each other.
4. The semiconductor device according to claim 1 , wherein the first metal oxide film, the second metal oxide film, the third metal oxide film, and the fourth metal oxide film each include a region where a proportion of oxygen is higher than a proportion of oxygen in stoichiometric composition.
5. The semiconductor device according to claim 1 , wherein the first metal oxide film and the fourth metal oxide film each contain one of aluminum oxide and aluminum gallium oxide.
6. The semiconductor device according to claim 1 , wherein the second metal oxide film and the third metal oxide film each contain one of gallium oxide and gallium aluminum oxide.
7. The semiconductor device according to claim 1 , wherein the oxide semiconductor film contains indium, gallium, and oxygen.
8. The semiconductor device according to claim 1 , wherein the oxide semiconductor film is surrounded by the second metal oxide film and the third metal oxide film.
9. The semiconductor device according to claim 1 , wherein, in the cross-sectional view, the third metal oxide film contacts an entirety of the top and peripheral side surfaces of at least one of the source electrode and the drain electrode, and the second metal oxide film and the oxide semiconductor film contacts an entirety of the bottom surface of at least one of the source electrode and the drain electrode.
10. A semiconductor device comprising:
a first metal oxide film;
a second metal oxide film over and in contact with the first metal oxide film;
an oxide semiconductor film over and in contact with the second metal oxide film;
a source electrode and a drain electrode electrically connected to the oxide semiconductor film;
a gate insulating film having a stacked structure including a third metal oxide film in contact with the oxide semiconductor film and a fourth metal oxide film in contact with the third metal oxide film; and
a gate electrode over the gate insulating film and in a region overlapping with the oxide semiconductor film,
wherein the first metal oxide film, the second metal oxide film, the third metal oxide film, and the fourth metal oxide film each contain a Group 13 element and oxygen,
wherein each of the source electrode and the drain electrode is surrounded by the second metal oxide film and the third metal oxide film in a cross-sectional view, such that the third metal oxide film contacts top and peripheral side surfaces of at least one of the source electrode and the drain electrode, and the second metal oxide film and the oxide semiconductor film contact a bottom surface of the at least one of the source electrode and the drain electrode.
11. The semiconductor device according to claim 10 , further comprising a conductive layer over the fourth metal oxide film and in a region overlapping with the oxide semiconductor film.
12. The semiconductor device according to claim 10 , wherein the second metal oxide film and the third metal oxide film are at least partly in contact with each other.
13. The semiconductor device according to claim 10 , wherein the first metal oxide film, the second metal oxide film, the third metal oxide film, and the fourth metal oxide film each include a region where a proportion of oxygen is higher than a proportion of oxygen in stoichiometric composition.
14. The semiconductor device according to claim 10 , wherein the first metal oxide film and the fourth metal oxide film each contain one of aluminum oxide and aluminum gallium oxide.
15. The semiconductor device according to claim 10 , wherein the second metal oxide film and the third metal oxide film each contain one of gallium oxide and gallium aluminum oxide.
16. The semiconductor device according to claim 10 , wherein the oxide semiconductor film contains indium, gallium, and oxygen.
17. The semiconductor device according to claim 10 , wherein the oxide semiconductor film is surrounded by the second metal oxide film and the third metal oxide film.
18. The semiconductor device according to claim 1 , wherein the semiconductor device is one selected from the group consisting of a laptop personal computer, a portable information terminal, an electronic book reader, a mobile phone, a digital video camera, and a television set.
19. The semiconductor device according to claim 10 , wherein the semiconductor device is one selected from the group consisting of a laptop personal computer, a portable information terminal, an electronic book reader, a mobile phone, a digital video camera, and a television set.
20. The semiconductor device according to claim 10 , wherein, in the cross-sectional view, the third metal oxide film contacts an entirety of the top and peripheral side surfaces of at least one of the source electrode and the drain electrode, and the second metal oxide film and the oxide semiconductor film contacts an entirety of the bottom surface of at least one of the source electrode and the drain electrode.