SEMICONDUCTOR DEVICE

• US 20110240994A1
• Filed: 03/29/2011
• Published: 10/06/2011
• Est. Priority Date: 04/02/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: YAMAZAKI, Shunpei
• Granted Patent: US 9,190,522 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

An object is to provide a semiconductor device including an oxide semiconductor, which has stable electric characteristics and high reliability. A semiconductor device includes an oxide semiconductor film, a source electrode and a drain electrode which are electrically connected to the oxide semiconductor film, a metal oxide film which is partly in contact with the oxide semiconductor film, a gate insulating film which is over and in contact with the metal oxide film, and a gate electrode over the gate insulating film. With such a structure, effect of charge on the oxide semiconductor film can be relaxed; thus, shift of the threshold voltage in the transistor, due to charge trapping at an interface of the oxide semiconductor film, can be suppressed.

Claims

1. A semiconductor device comprising:

an oxide semiconductor film;

a source electrode and a drain electrode electrically connected to the oxide semiconductor film;

a metal oxide film on and in contact with the oxide semiconductor film;

a gate insulating film on and in contact with the metal oxide film; and

a gate electrode over the gate insulating film.

2. The semiconductor device according to claim 1, wherein the metal oxide film comprises an oxide of one or more of metal elements included in the oxide semiconductor film.

3. The semiconductor device according to claim 1, wherein an energy gap of the metal oxide film is larger than an energy gap of the oxide semiconductor film.

4. 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.

5. The semiconductor device according to claim 1, wherein the metal oxide film comprises gallium oxide.

6. The semiconductor device according to claim 1, wherein the gate insulating film comprises silicon oxide or hafnium oxide.

7. The semiconductor device according to claim 1, wherein the gate insulating film comprises aluminum oxide or aluminum nitride.

8. The semiconductor device according to claim 1, wherein at least a part of a top surface of the oxide semiconductor film is in contact with the source electrode and the drain electrode.

9. The semiconductor device according to claim 1, wherein at least a part of a top surface of the source electrode and a part of a top surface of the drain electrode are in contact with the oxide semiconductor film.

10. The semiconductor device according to claim 1,

wherein at least a part of a top surface of the source electrode and a part of a top surface of the drain electrode are in contact with the oxide semiconductor film, and

wherein a side edge portion of the oxide semiconductor film and a side edge portion of the metal oxide film are aligned with each other in a channel length direction.

11. The semiconductor device according to claim 1, further comprising an insulating film that covers the gate insulating film and the gate electrode.

12. The semiconductor device according to claim 1, further comprising a conductive film below the oxide semiconductor film.

13. A semiconductor device comprising:

an oxide semiconductor film;

a source electrode and a drain electrode electrically connected to the oxide semiconductor film;

a metal oxide film on and in contact with the oxide semiconductor film;

a first insulating film on and in contact with the metal oxide film; and

a gate electrode over the first insulating film,

wherein an energy gap of the metal oxide film is larger than an energy gap of the oxide semiconductor film.

14. The semiconductor device according to claim 13, wherein the metal oxide film comprises an oxide of one or more of metal elements included in the oxide semiconductor film.

15. The semiconductor device according to claim 13, 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.

16. The semiconductor device according to claim 13, wherein the metal oxide film comprises gallium oxide.

17. The semiconductor device according to claim 13, wherein the first insulating film comprises silicon oxide or hafnium oxide.

18. The semiconductor device according to claim 13, wherein the first insulating film comprises aluminum oxide or aluminum nitride.

19. The semiconductor device according to claim 13, wherein at least a part of a top surface of the oxide semiconductor film is in contact with the source electrode and the drain electrode.

20. The semiconductor device according to claim 13, wherein at least a part of a top surface of the source electrode and a part of a top surface of the drain electrode are in contact with the oxide semiconductor film.

21. The semiconductor device according to claim 13,

wherein at least a part of a top surface of the source electrode and a part of a top surface of the drain electrode are in contact with the oxide semiconductor film, and

wherein a side edge portion of the oxide semiconductor film and a side edge portion of the metal oxide film are aligned with each other in a channel length direction.

22. The semiconductor device according to claim 13, further comprising a second insulating film that covers the first insulating film and the gate electrode.

23. The semiconductor device according to claim 13, further comprising a conductive film below the oxide semiconductor film.