Semiconductor device and manufacturing method thereof

• US 9,666,719 B2
• Filed: 07/29/2009
• Issued: 05/30/2017
• Est. Priority Date: 07/31/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Miyairi, Hidekazu, Akimoto, Kengo, Shiraishi, Kojiro, Miyanaga, Akiharu, Yamazaki, Shunpei
• Primary Examiner(s): Smoot, Stephen W
• Assistant Examiner(s): KIM, SUN M
• Application Number:
  US12/511,252
• Publication Number:
  US 20100025676A1
• Time in Patent Office: 2,862 Days
• Field of Search: 438104, 257 43, 257E29296
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• 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 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• 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

To offer a semiconductor device including a thin film transistor having excellent characteristics and high reliability and a method for manufacturing the semiconductor device without variation. The summary is to include an inverted-staggered (bottom-gate structure) thin film transistor in which an oxide semiconductor film containing In, Ga, and Zn is used for a semiconductor layer and a buffer layer is provided between the semiconductor layer and source and drain electrode layers. An ohmic contact is formed by intentionally providing a buffer layer containing In, Ga, and Zn and having a higher carrier concentration than the semiconductor layer between the semiconductor layer and the source and drain electrode layers.

Claims

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

forming a gate electrode layer over a substrate;

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

performing a first plasma treatment on the first gate insulating film;

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

forming an oxide semiconductor layer over the second gate insulating film;

performing a second plasma treatment on the oxide semiconductor layer in an atmosphere containing Cl₂ or CF₄;

forming a channel protective layer over the oxide semiconductor layer;

forming a pair of buffer layers over the oxide semiconductor layer; and

forming source and drain electrode layers over the pair of buffer layers,

wherein the pair of buffer layers covers edge portions of the oxide semiconductor layer,

wherein a carrier concentration of the pair of buffer layers is higher than that of the oxide semiconductor layer, and

wherein the oxide semiconductor layer and the source and drain electrode layers are electrically connected to each other through the pair of buffer layers.

2. The method for manufacturing a semiconductor device according to claim 1, wherein the oxide semiconductor layer comprises indium, gallium, and zinc.

3. The method for manufacturing a semiconductor device, according to claim 1, wherein the second gate insulating film, the oxide semiconductor layer, and the channel protective layer are formed by a sputtering method.

4. The method for manufacturing a semiconductor device, according to claim 1, wherein the second gate insulating film, the oxide semiconductor layer, and the channel protective layer are formed in an oxygen atmosphere.

5. The method for manufacturing a semiconductor device, according to claim 1, wherein the pair of buffer layers are formed in a rare gas atmosphere.

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

wherein the carrier concentration of the oxide semiconductor layer is less than 1×

10¹⁷ atoms/cm³, and

wherein the carrier concentration of the pair of buffer layers is 1×

10¹⁸ atoms/cm³ or more.

7. The method for manufacturing a semiconductor device, according to claim 1, wherein the pair of buffer layers comprises an oxide semiconductor including magnesium, aluminum, or titanium.

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

forming a gate electrode layer over a substrate;

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

performing a first plasma treatment on the first gate insulating film;

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

forming an oxide semiconductor layer over the second gate insulating film;

performing a second plasma treatment on the oxide semiconductor layer in an atmosphere containing Cl₂ or CF₄;

forming a channel protective layer over the oxide semiconductor layer;

forming a pair of buffer layers over the oxide semiconductor layer; and

forming source and drain electrode layers over the pair of buffer layers,

wherein the pair of buffer layers covers edge portions of the oxide semiconductor layer,

wherein the channel protective layer comprises a halogen element and an excessive amount of oxygen,

wherein a carrier concentration of the pair of buffer layers is higher than that of the oxide semiconductor layer,

wherein the oxide semiconductor layer and the source and drain electrode layers are electrically connected to each other through the pair of buffer layers, and

wherein the first gate insulating film, the second gate insulating film, the oxide semiconductor layer, and the channel protective layer are successively formed without being exposed to the air.

9. The method for manufacturing a semiconductor device according to claim 8, wherein the oxide semiconductor layer comprises indium, gallium, and zinc.

10. The method for manufacturing a semiconductor device, according to claim 8, wherein the second gate insulating film, the oxide semiconductor layer, and the channel protective layer are formed by a sputtering method.

11. The method for manufacturing a semiconductor device, according to claim 8, wherein the second gate insulating film, the oxide semiconductor layer, and the channel protective layer are formed in an oxygen atmosphere.

12. The method for manufacturing a semiconductor device, according to claim 8, wherein the pair of buffer layers are formed in a rare gas atmosphere.

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

wherein the carrier concentration of the oxide semiconductor layer is less than 1×

10¹⁷ atoms/cm³, and

wherein the carrier concentration of the pair of buffer layers is 1×

10¹⁸ atoms/cm³ or more.

14. The method for manufacturing a semiconductor device, according to claim 8, wherein the pair of buffer layers comprises an oxide semiconductor including magnesium, aluminum, or titanium.

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

forming a gate electrode layer over a substrate;

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

performing a first plasma treatment on the first gate insulating film;

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

forming an oxide semiconductor layer over the second gate insulating film;

performing a second plasma treatment on the oxide semiconductor layer in an atmosphere containing Cl₂ or CF₄;

forming a channel protective layer over the oxide semiconductor layer;

forming a pair of buffer layers over the oxide semiconductor layer; and

forming source and drain electrode layers over the pair of buffer layers,

wherein the channel protective layer comprises a halogen element and an excessive amount of oxygen,

wherein a carrier concentration of the pair of buffer layers is higher than that of the oxide semiconductor layer, and wherein the oxide semiconductor layer and the source and drain electrode layers are electrically connected to each other through the pair of buffer layers.

16. The method for manufacturing a semiconductor device according to claim 15, wherein the oxide semiconductor layer comprises indium, gallium, and zinc.

17. The method for manufacturing a semiconductor device, according to claim 15, wherein the second gate insulating film, the oxide semiconductor layer, and the channel protective layer are formed by a sputtering method.

18. The method for manufacturing a semiconductor device, according to claim 15, wherein the second gate insulating film, the oxide semiconductor layer, and the channel protective layer are formed in an oxygen atmosphere.

19. The method for manufacturing a semiconductor device, according to claim 15, wherein the pair of buffer layers are formed in a rare gas atmosphere.

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

wherein the carrier concentration of the oxide semiconductor layer is less than 1×

10¹⁷ atoms/cm³, and

wherein the carrier concentration of the pair of buffer layers is 1×

10¹⁸ atoms/cm³ or more.

21. The method for manufacturing a semiconductor device, according to claim 15, wherein the pair of buffer layers comprises an oxide semiconductor including magnesium, aluminum, or titanium.