Semiconductor device

• US 9,812,582 B2
• Filed: 12/11/2015
• Issued: 11/07/2017
• Est. Priority Date: 02/02/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): LE, DUNG ANH
• Application Number:
  US14/966,177
• Publication Number:
  US 20160099353A1
• Time in Patent Office: 697 Days
• Field of Search: 257 40, 257 43, 257 57, 257 72, 257 79
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A semiconductor device in which a first oxide film, a second oxide film, and a third oxide film are stacked over an insulating surface is provided. In the semiconductor device, each of the first oxide film, the second oxide film, and the third oxide film comprises indium, gallium, and zinc. The third oxide film is in contact with a side surface of the second oxide film. A gallium content is higher than an indium content in the third oxide film. The gallium content is higher than a zinc content in the third oxide film. An indium content in the second oxide film is higher than the indium content in the third oxide film.

Claims

1. A semiconductor device comprising:

a first oxide film over an insulating surface;

a second oxide film over the first oxide film; and

a third oxide film over the second oxide film,

wherein the third oxide film is in contact with a side surface of the second oxide film,

wherein each of the first oxide film, the second oxide film, and the third oxide film comprises indium, gallium, and zinc,

wherein a gallium content is higher than an indium content in the third oxide film,

wherein the gallium content is higher than a zinc content in the third oxide film, and

wherein an indium content in the second oxide film is higher than the indium content in the third oxide film.

2. The semiconductor device according to claim 1, wherein an atomic, ratio of indium, gallium, and zinc in the third oxide film is substantially 1:

3;

2.

3. The semiconductor device according to claim 1, wherein the third oxide film comprises a c-axis aligned crystal part.

4. The semiconductor device according to claim 1, wherein the third oxide film has an insulating property.

5. The semiconductor device according to claim 1, wherein the third oxide film is in contact with a side surface of the first oxide film.

6. The semiconductor device according to claim 1, further comprising an insulating film and a gate electrode, wherein the insulating film is provided between the gate electrode and the third oxide film.

7. The semiconductor device according to claim 1, wherein the second oxide film comprises a channel formation region.

8. The semiconductor device according to claim 1, wherein an energy gap of the third oxide film is higher than an energy gap of the second oxide film.

9. The semiconductor device according to claim 1, wherein the second oxide film comprises nitrogen.

10. A semiconductor device comprising:

a first oxide film over an insulating surface;

a second oxide film over the first oxide film;

a third oxide film over the second oxide film; and

an electrode in contact with the second oxide film,

wherein the third oxide film is in contact with a side surface of the second oxide film,

wherein each of the first oxide film, the second oxide film, and the third oxide film comprises indium, gallium, and zinc,

wherein a gallium content is higher than an indium content in the third oxide film,

wherein the gallium content is higher than a zinc content in the third oxide film, and

wherein an indium content in the second oxide film is higher than the indium content in the third oxide film.

11. The semiconductor device according to claim 10, wherein an atomic ratio of indium, gallium, and zinc in the third oxide film is substantially 1:

3;

2.

12. The semiconductor device according to claim 10, wherein the third oxide film comprises a c-axis aligned crystal part.

13. The semiconductor device according to claim 10, wherein the third oxide film has an insulating property.

14. The semiconductor device according to claim 10, wherein the third oxide film is in contact with a side surface of the first oxide film.

15. The semiconductor device according to claim 10, further comprising an insulating film and a gate electrode,

wherein the insulating film is provided between the gate electrode and the third oxide film.

16. The semiconductor device according to claim 10, wherein the second oxide film comprises a channel formation region.

17. The semiconductor device according to claim 10, wherein an energy gap of the third oxide film is higher than an energy gap of the second oxide film.

18. The semiconductor device according to claim 10, wherein the second oxide film comprises nitrogen.

19. The semiconductor device according to claim 10, wherein the electrode comprises a nitride of tantalum.

20. A semiconductor device comprising:

a first oxide film over an insulating surface;

a second oxide film over the first oxide film;

a third oxide film over the second oxide film;

an insulating film over the third oxide film; and

a gate electrode over the insulating film,

wherein the third oxide film is in contact with a side surface of the second oxide film,

wherein each of the first oxide film, the second oxide film, and the third oxide film comprises indium, gallium, and zinc,

wherein an indium content in the second oxide film is higher than an indium content in the first oxide film,

wherein a gallium content in the second oxide film is lower than a gallium content in the first oxide film,

wherein a gallium content is higher than an indium content in the third oxide film, and

wherein the indium content in the second oxide film is higher than the indium content in the third oxide film.

21. The semiconductor device according to claim 20, wherein an atomic ratio of indium, gallium, and zinc in the third oxide film is substantially 1:

3;

2.

22. The semiconductor device according to claim 20, wherein the third oxide film comprises a c-axis aligned crystal part.

23. The semiconductor device according to claim 20, wherein the third oxide film has an insulating property.

24. The semiconductor device according to claim 20, wherein the third oxide film is in contact with a side surface of the first oxide film.

25. The semiconductor device according to claim 20, wherein the second oxide film comprises a channel formation region.

26. The semiconductor device according to claim 20, wherein an energy gap of the third oxide film is higher than an energy gap of the second oxide film.

27. The semiconductor device according to claim 20, wherein the second oxide film comprises nitrogen.