Semiconductor device and method for manufacturing semiconductor device

• US 9,634,082 B2
• Filed: 02/29/2016
• Issued: 04/25/2017
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Takahashi, Masahiro, Maruyama, Tetsunori
• Primary Examiner(s): Lee, Calvin
• Application Number:
  US15/056,286
• Publication Number:
  US 20160181434A1
• Time in Patent Office: 421 Days
• Field of Search: 257335, 257325, 257 67, 257 43, 257E31034, 257E31047, 438162, 438104
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02472 Oxides
• CPC Class Codes: H01L 21/02483 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02502 consisting of two layers
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/0259 Microstructure
• CPC Class Codes: H01L 29/06 characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
• CPC Class Codes: H01L 29/36 characterised by the concentration or distribution of impurities in the bulk material within semiconductor regions H01L29/06
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• 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

Abstract

A highly reliable semiconductor device is manufactured by giving stable electric characteristics to a transistor in which an oxide semiconductor film is used for a channel. An oxide semiconductor film which can have a first crystal structure by heat treatment and an oxide semiconductor film which can have a second crystal structure by heat treatment are formed so as to be stacked, and then heat treatment is performed; accordingly, crystal growth occurs with the use of an oxide semiconductor film having the second crystal structure as a seed, so that an oxide semiconductor film having the first crystal structure is formed. An oxide semiconductor film formed in this manner is used for an active layer of the transistor.

Claims

1. A semiconductor device comprising:

a first insulating film;

a second insulating film overlapping the first insulating film;

a stack of semiconductor films interposed between the first insulating film and the second insulating film, the stack of semiconductor films comprising;

a first oxide semiconductor film; and

a second oxide semiconductor film on and in contact with the first oxide semiconductor film; and

a gate electrode,

wherein the gate electrode and the stack of semiconductor films overlap, and

wherein a concentration in nitrogen of the first oxide semiconductor film is higher than a concentration in nitrogen of the second oxide semiconductor film.

2. The semiconductor device according to claim 1,

wherein a crystal structure of the second oxide semiconductor film is one of a YbFe₂O₄ structure, a Yb₂Fe₃O₇ structure, a deformed structure of a YbFe₂O₄ structure, and a deformed structure of a Yb₂Fe₃O₇.

3. The semiconductor device according to claim 1,

wherein a crystal structure of the second oxide semiconductor film is a wurtzite structure.

4. The semiconductor device according to claim 1,

wherein the second oxide semiconductor film contains nitrogen at a concentration higher than or equal to 1×

10¹⁷/cm³ and lower than 5×

10¹⁹/cm³ in a channel region.

5. The semiconductor device according to claim 1,

wherein the first oxide semiconductor film contains nitrogen at a concentration higher than or equal to 5×

10¹⁹/cm³, and lower than 7 at. % in a channel region.

6. The semiconductor device according to claim 5,

wherein the concentration is higher than or equal to 1×

10²⁰/cm³.

7. The semiconductor device according to claim 1,

wherein the first oxide semiconductor film is non-single-crystal and comprises an amorphous region and a crystal region having c-axis alignment.

8. The semiconductor device according to claim 1,

wherein the second oxide semiconductor film is non-single-crystal and comprises an amorphous region and a crystal region having c-axis alignment.

9. The semiconductor device according to claim 1,

wherein the first oxide semiconductor film and the second oxide semiconductor film are each non-single-crystal and comprise each an amorphous region and a crystal region having c-axis alignment.

10. A semiconductor device comprising:

a gate electrode;

a first insulating film over the gate electrode;

a second insulating film overlapping the first insulating film; and

a stack of semiconductor films interposed between the first insulating film and the second insulating film, the stack of semiconductor films comprising;

a first oxide semiconductor film; and

a second oxide semiconductor film on and in contact with the first oxide semiconductor film,

wherein the gate electrode and the stack of semiconductor films overlap, and

wherein a concentration in nitrogen of the first oxide semiconductor film is higher than a concentration in nitrogen of the second oxide semiconductor film.

11. The semiconductor device according to claim 10,

wherein a crystal structure of the second oxide semiconductor film is one of a YbFe₂O₄ structure, a Yb₂Fe₃O₇ structure, a deformed structure of a YbFe₂O₄ structure, and a deformed structure of a Yb₂Fe₃O₇.

12. The semiconductor device according to claim 10,

wherein a crystal structure of the second oxide semiconductor film is a wurtzite structure.

13. The semiconductor device according to claim 10,

wherein the second oxide semiconductor film contains nitrogen at a concentration higher than or equal to 1×

10¹⁷/cm³ and lower than 5×

10¹⁹/cm³ in a channel region.

14. The semiconductor device according to claim 10,

wherein the first oxide semiconductor film contains nitrogen at a concentration higher than or equal to 5×

10¹⁹/cm³, and lower than 7 at. % in a channel region.

15. A semiconductor device comprising:

a first insulating film;

a second insulating film overlapping the first insulating film;

a gate electrode over the second insulating film; and

a stack of semiconductor films interposed between the first insulating film and the second insulating film, the stack of semiconductor films comprising;

a first oxide semiconductor film; and

a second oxide semiconductor film on and in contact with the first oxide semiconductor film,

wherein the gate electrode and the stack of semiconductor films overlap, and

wherein a concentration in nitrogen of the first oxide semiconductor film is higher than a concentration in nitrogen of the second oxide semiconductor film.

16. The semiconductor device according to claim 15,

wherein a crystal structure of the second oxide semiconductor film is one of a YbFe₂O₄ structure, a Yb₂Fe₃O₇ structure, a deformed structure of a YbFe₂O₄ structure, and a deformed structure of a Yb₂Fe₃O₇.

17. The semiconductor device according to claim 15,

wherein a crystal structure of the second oxide semiconductor film is a wurtzite structure.

18. The semiconductor device according to claim 15,

wherein the second oxide semiconductor film contains nitrogen at a concentration higher than or equal to 1×

10¹⁷/cm³ and lower than 5×

10¹⁹/cm³ in a channel region.

19. The semiconductor device according to claim 15,

wherein the first oxide semiconductor film contains nitrogen at a concentration higher than or equal to 5×

10¹⁹/cm³, and lower than 7 at. % in a channel region.

20. A semiconductor device comprising:

a first gate electrode,

a first insulating film over the first gate electrode;

a second insulating film overlapping the first insulating film;

a second gate electrode over the second insulating film; and

a stack of semiconductor films interposed between the first insulating film and the second insulating film, the stack of semiconductor films comprising;

a first oxide semiconductor film; and

a second oxide semiconductor film on and in contact with the first oxide semiconductor film,

wherein the first gate electrode, the stack of semiconductor films, and the second gate electrode overlap,

wherein a concentration in nitrogen of the first oxide semiconductor film is higher than a concentration in nitrogen of the second oxide semiconductor film.