SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

• US 20120132904A1
• Filed: 11/16/2011
• Published: 05/31/2012
• 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
• Granted Patent: US 8,629,496 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• 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 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• 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

Abstract

An object to provide a material suitably used for used for a semiconductor included in a transistor, a diode, or the like, with the use of a sputtering method. Specifically, an object is to provide a manufacturing process an oxide semiconductor film having high crystallinity. By intentionally adding nitrogen to the oxide semiconductor, an oxide semiconductor film having a wurtzite crystal structure that is a hexagonal crystal structure is formed. In the oxide semiconductor film, the crystallinity of a region containing nitrogen is higher than that of a region hardly containing nitrogen or a region to which nitrogen is not intentionally added. The oxide semiconductor film having high crystallinity and having a wurtzite crystal structure is used as a channel formation region of a transistor.

Claims

1. A semiconductor device comprising:

a gate electrode layer;

a first insulating layer in contact with the gate electrode layer;

an oxide semiconductor layer in contact with the first insulating layer; and

a second insulating layer in contact with the oxide semiconductor layer,

wherein the oxide semiconductor layer has a wurtzite crystal structure and has a concentration gradient in which a nitrogen concentration is increased as a distance from the first insulating layer becomes shorter.

2. A semiconductor device comprising:

a gate electrode layer;

a first insulating layer in contact with the gate electrode layer;

a first oxide semiconductor layer in contact with the first insulating layer;

a second oxide semiconductor layer in contact with the first oxide semiconductor layer; and

a second insulating layer in contact with the second oxide semiconductor layer,

wherein the first oxide semiconductor layer and the second oxide semiconductor layer each have a wurtzite crystal structure, and

wherein the first oxide semiconductor layer has a higher nitrogen concentration than the second oxide semiconductor layer.

3. The semiconductor device according to claim 2, wherein the nitrogen concentration of the first oxide semiconductor layer is higher than or equal to 0.1 atomic % and lower than 7 atomic %.

4. The semiconductor device according to claim 2, wherein the nitrogen concentration of the second oxide semiconductor layer is higher than or equal to 1×

10¹⁷/cm³ and lower than 5×

10¹⁹/cm³.

5. A method for manufacturing a semiconductor device, comprising the steps of:

forming an insulating film containing nitrogen over a substrate including an insulating surface;

introducing the substrate over which the insulating film containing nitrogen is formed, into a vacuum chamber;

forming a first oxide semiconductor film containing nitrogen by sputtering in a nitrogen containing atmosphere under a first deposition condition that a substrate temperature is higher than or equal to 150°

C. and lower than or equal to 450°

C.; and

forming a second oxide semiconductor film containing nitrogen by sputtering in a nitrogen containing atmosphere under a second deposition condition that a substrate temperature is higher than or equal to 150°

C. and lower than or equal to 450°

C.

6. The method for manufacturing a semiconductor device according to claim 5, further comprising the step of performing heat treatment at a temperature higher than or equal to 150°

C. and lower than or equal to 650°

C. after the deposition is performed under the second deposition condition.

7. The method for manufacturing a semiconductor device according to claim 5, wherein a percentage of a flow rate of a nitrogen gas with respect to a total flow rate of a sputtering gas under the first deposition condition is different from a percentage of a flow rate of a nitrogen gas with respect to a total flow rate of a sputtering gas under the second deposition condition.

8. The method for manufacturing a semiconductor device according to claim 5, wherein a percentage of a flow rate of a nitrogen gas with respect to a total flow rate of a sputtering gas which is introduced into the vacuum chamber is greater than or equal to 90% and less than or equal to 100% under the first deposition condition.

9. The method for manufacturing a semiconductor device according to claim 5, wherein a nitrogen gas is introduced into the vacuum chamber while the nitrogen gas is heated under the first deposition condition.

10. The method for manufacturing a semiconductor device according to claim 5, wherein a sputtering gas which includes an oxygen gas or a rare gas besides the nitrogen gas is introduced under the second deposition condition.

11. The method for manufacturing a semiconductor device according to claim 5, further comprising the step of performing nitrogen plasma treatment on a surface of the insulating film containing nitrogen after the insulating film containing nitrogen is formed.

12. The method for manufacturing a semiconductor device according to claim 5, wherein the insulating film containing nitrogen is formed by nitrogen plasma treatment on a surface of an insulating film .

13. A method for manufacturing a semiconductor device, comprising the steps of:

forming a gate electrode layer over a substrate including an insulating surface;

forming an insulating film containing nitrogen over the gate electrode layer;

introducing the substrate over which the gate electrode layer and the insulating film containing nitrogen are formed, into a vacuum chamber;

forming a first oxide semiconductor film containing nitrogen by sputtering in a nitrogen containing atmosphere under a first deposition condition that a substrate temperature is higher than or equal to 150°

C. and lower than or equal to 450°

C.; and

forming a second oxide semiconductor film containing nitrogen by sputtering in a nitrogen containing atmosphere under a second deposition condition that a substrate temperature is higher than or equal to 150°

C. and lower than or equal to 450°

C.

14. The method for manufacturing a semiconductor device according to claim 13, further comprising the step of performing heat treatment at a temperature higher than or equal to 150°

C. and lower than or equal to 650°

C. after the deposition is performed under the second deposition condition.

15. The method for manufacturing a semiconductor device according to claim 13, wherein a percentage of a flow rate of a nitrogen gas with respect to a total flow rate of a sputtering gas under the first deposition condition is greater than a percentage of a flow rate of a nitrogen gas with respect to a total flow rate of a sputtering gas under the second deposition condition.

16. The method for manufacturing a semiconductor device according to claim 13, wherein a percentage of a flow rate of a nitrogen gas with respect to a total flow rate of a sputtering gas which is introduced into the vacuum chamber is greater than or equal to 90% and less than or equal to 100% under the first deposition condition.

17. The method for manufacturing a semiconductor device according to claim 13, wherein a nitrogen gas is introduced into the vacuum chamber while the nitrogen gas is heated under the first deposition condition.

18. The method for manufacturing a semiconductor device according to claim 13, wherein a sputtering gas which includes an oxygen gas or a rare gas besides the nitrogen gas is introduced under the second deposition condition.

19. The method for manufacturing a semiconductor device according to claim 13, further comprising the step of performing nitrogen plasma treatment on a surface of the insulating film containing nitrogen after the insulating film containing nitrogen is formed.

20. The method for manufacturing a semiconductor device according to claim 13, wherein the insulating film containing nitrogen is formed by nitrogen plasma treatment on a surface of an insulating film.