Semiconductor device having an oxide semiconductor

• US 9,190,522 B2
• Filed: 03/29/2011
• Issued: 11/17/2015
• 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
• Primary Examiner(s): PARENDO, KEVIN A
• Application Number:
  US13/074,658
• Publication Number:
  US 20110240994A1
• Time in Patent Office: 1,694 Days
• Field of Search: 257/43, 257/410, 257/E29.273
• US Class Current: 1/1
• 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 comprising a channel formation region;

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

a gallium oxide film over the oxide semiconductor film, the source electrode and the drain electrode;

a gate insulating film over and in contact with the gallium oxide film; and

a gate electrode over the gate insulating film,

wherein the gate electrode and the channel formation region overlap each other with the gate insulating film therebetween, and

wherein the gallium oxide film is in contact with an outer side surface of each of the source electrode and the drain electrode.

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

3. The semiconductor device according to claim 1, wherein an energy at a bottom of a conduction band of the gallium oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.

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

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

6. 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.

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

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

9. The semiconductor device according to claim 1, wherein the gallium oxide film is in contact with side surfaces of the oxide semiconductor film in a channel width direction.

10. A semiconductor device comprising:

an oxide semiconductor film comprising a channel formation region;

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

a metal oxide film over the oxide semiconductor film, the source electrode and the drain electrode;

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

a gate electrode over the gate insulating film,

wherein the gate electrode and the channel formation region overlap each other with the gate insulating film therebetween,

wherein the metal oxide film is in contact with an outer side surface of each of the source electrode and the drain electrode, and

wherein the metal oxide film comprises one or more metal elements included in the oxide semiconductor film.

11. The semiconductor device according to claim 10, wherein an energy gap of the metal oxide film is larger than an energy gap of the oxide semiconductor film.

12. The semiconductor device according to claim 10, 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.

13. The semiconductor device according to claim 10, wherein the metal oxide film comprises gallium.

14. The semiconductor device according to claim 10, wherein the gate insulating film comprises silicon oxide or hafnium oxide.

15. The semiconductor device according to claim 10, wherein the gate insulating film comprises aluminum oxide or aluminum nitride.

16. The semiconductor device according to claim 10, 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.

17. The semiconductor device according to claim 10, further comprising an insulating film that covers the gate insulating film and the gate electrode.

18. The semiconductor device according to claim 10, wherein the metal oxide film is in contact with a top surface of the oxide semiconductor film between the source electrode and the drain electrode.

19. The semiconductor device according to claim 10, wherein the metal oxide film is in contact with side surfaces of the oxide semiconductor film in a channel width direction.