Semiconductor device and method for manufacturing the same

• US 8,809,154 B2
• Filed: 12/20/2012
• Issued: 08/19/2014
• Est. Priority Date: 12/27/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koezuka, Junichi, Okazaki, Kenichi, Hosaka, Yasuharu, Yamazaki, Shunpei, Ikeyama, Terumasa
• Primary Examiner(s): Picardat, Kevin M
• Application Number:
  US13/721,972
• Publication Number:
  US 20130164899A1
• Time in Patent Office: 607 Days
• Field of Search: 438/149, 438/151, 438/158, 438/164, 438/299, 438/300, 438/301
• US Class Current: 438/299
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 21/0214 the material being a silicon oxynitride, e.g. SiON or SiON:H
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/02318 post-treatment
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/02365 Forming inorganic semiconducting materials on a substrate for light-sensitive devices H01L31/00
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• 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 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66477 with an insulated gate, i.e. MISFET
• 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

A highly reliable semiconductor device in which a transistor including an oxide semiconductor film has stable electric characteristics is manufactured. In the semiconductor device which includes an inverted-staggered transistor having a bottom-gate structure and being provided over a substrate having an insulating surface, at least a first gate insulating film and a second gate insulating film are provided between a gate electrode layer and an oxide semiconductor film, and heat treatment is performed at a temperature of 450° C. or higher, preferably 650° C. or higher, and then the oxide semiconductor film is formed. By the heat treatment at a temperature of 450° C. or higher before the formation of the oxide semiconductor film, diffusion of hydrogen elements into the oxide semiconductor film, which causes degradation or variations in electric characteristics of the transistor, can be reduced, so that the transistor can have stable electric characteristics.

Claims

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

forming a gate electrode layer over a substrate;

forming a first gate insulating film over the gate electrode layer;

forming a second gate insulating film over the first gate insulating film;

performing a first heat treatment at a temperature higher than or equal to 450°

C. after the formation of the second gate insulating film;

forming an oxide semiconductor film over the second gate insulating film after the first heat treatment; and

performing a second heat treatment after the formation of the oxide semiconductor film,

wherein the first gate insulating film is formed by a plasma CVD method using a first RF power, a silane gas, a nitrogen gas, and an ammonia gas,

wherein the second gate insulating film is formed by a plasma CVD method using a second RF power, a silane gas and a nitrogen dioxide gas, and

wherein the first RF power is higher than the second RF power.

3. The method for manufacturing a semiconductor device, according to claim 1,

wherein the temperature is equal to or higher than 650°

C.

5. The method for manufacturing a semiconductor device, according to claim 1,

wherein a flow rate of the silane gas used to form the first gate insulating layer is higher than a flow rate of the silane gas used to form the second gate insulating layer.

7. The method for manufacturing a semiconductor device, according to claim 1,

wherein the first gate insulating film is formed at a higher pressure than the second gate insulating film,

wherein the first gate insulating film is a silicon nitride film and the second gate insulating film is a silicon oxynitride film.

9. The method for manufacturing a semiconductor device, according to claim 1,

wherein the first gate insulating film is a silicon nitride film and the second gate insulating film is a silicon oxynitride film, and

wherein the second gate insulating film is thicker than the first gate insulating film.

11. The method for manufacturing a semiconductor device, according to claim 1, further comprising the step of:

forming an oxide layer on and in contact with the oxide semiconductor film.

13. The method for manufacturing a semiconductor device, according to claim 1,

wherein the oxide semiconductor film is a c-axis aligned crystalline oxide semiconductor film.

15. The method for manufacturing a semiconductor device, according to claim 1,

wherein TDS measurements evidence a reduction in hydrogen concentration of the first gate insulating film when the first heat treatment is performed.

17. The method for manufacturing a semiconductor device, according to claim 1,

wherein TDS measurements evidence a reduction in hydrogen release due to the first heat treatment.

19. The method for manufacturing a semiconductor device, according to claim 1,

wherein a transistor comprising the oxide semiconductor film as an active layer is a normally-off transistor.

21. A method for manufacturing a display device comprising the method for manufacturing a semiconductor device according to claim 1.

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

forming a gate electrode layer over a substrate;

forming a first gate insulating film over the gate electrode layer;

forming a second gate insulating film over the first gate insulating film;

performing a first heat treatment at a temperature higher than or equal to 450°

C. after the formation of the second gate insulating film;

forming an oxide semiconductor film over the second gate insulating film after the first heat treatment;

performing a second heat treatment after the formation of the oxide semiconductor film;

forming a source electrode layer and a drain electrode layer over and in electrical contact with the oxide semiconductor film after the second heat treatment; and

performing a third heat treatment after the formation of the source electrode layer and the drain electrode layer,

wherein the first gate insulating film is formed by a plasma CVD method using a first RF power, a silane gas, a nitrogen gas, and an ammonia gas,

wherein the second gate insulating film is formed by a plasma CVD method using a second RF power, a silane gas and a nitrogen dioxide gas, and

wherein the first RF power is higher than the second RF power.

4. The method for manufacturing a semiconductor device, according to claim 2,

wherein the temperature is equal to or higher than 650°

C.

6. The method for manufacturing a semiconductor device, according to claim 2,

wherein a flow rate of the silane gas used to form the first gate insulating layer is higher than a flow rate of the silane gas used to form the second gate insulating layer.

8. The method for manufacturing a semiconductor device, according to claim 2,

wherein the first gate insulating film is formed at a higher pressure than the second gate insulating film,

wherein the first gate insulating film is a silicon nitride film and the second gate insulating film is a silicon oxynitride film.

10. The method for manufacturing a semiconductor device, according to claim 2,

wherein the first gate insulating film is a silicon nitride film and the second gate insulating film is a silicon oxynitride film, and

wherein the second gate insulating film is thicker than the first gate insulating film.

12. The method for manufacturing a semiconductor device, according to claim 2, further comprising the step of:

forming an oxide layer on and in contact with the oxide semiconductor film.

14. The method for manufacturing a semiconductor device, according to claim 2,

wherein the oxide semiconductor film is a c-axis aligned crystalline oxide semiconductor film.

16. The method for manufacturing a semiconductor device, according to claim 2,

wherein TDS measurements evidence a reduction in hydrogen concentration of the first gate insulating film when the first heat treatment is performed.

18. The method for manufacturing a semiconductor device, according to claim 2,

wherein TDS measurements evidence a reduction in hydrogen release due to the first heat treatment.

20. The method for manufacturing a semiconductor device, according to claim 2,

wherein a transistor comprising the oxide semiconductor film as an active layer is a normally-off transistor.

22. A method for manufacturing a display device comprising the method for manufacturing a semiconductor device according to claim 2.