Semiconductor device and method for manufacturing the same

• US 8,329,506 B2
• Filed: 11/16/2009
• Issued: 12/11/2012
• Est. Priority Date: 11/20/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Akimoto, Kengo, Sakata, Junichiro, Hirohashi, Takuya, Takahashi, Masahiro, Kishida, Hideyuki, Miyanaga, Akiharu
• Primary Examiner(s): Landau, Matthew
• Assistant Examiner(s): Kim, Sun M
• Application Number:
  US12/618,944
• Publication Number:
  US 20100123130A1
• Time in Patent Office: 1,121 Days
• Field of Search: 438/104, 438/166, 257/E21.462, 257E21471-E21472, 257/E21.475
• US Class Current: 438/104
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/28079 the final conductor layer next to the insulator being a single metal, e.g. Ta, W, Mo, Al
• CPC Class Codes: H01L 21/28158 Making the insulator
• 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 29/66742 Thin film unipolar transistors
• 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

It is an object to provide an oxide semiconductor which is suitable for use in a semiconductor device. Alternatively, it is another object to provide a semiconductor device using the oxide semiconductor. Provided is a semiconductor device including an In—Ga—Zn—O based oxide semiconductor layer in a channel formation region of a transistor. In the semiconductor device, the In—Ga—Zn—O based oxide semiconductor layer has a structure in which crystal grains represented by InGaO₃(ZnO)_m (m=1) are included in an amorphous structure represented by InGaO₃(ZnO)_m (m>0).

Claims

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

forming an In—

Ga—

Zn—

O based oxide semiconductor layer having an amorphous structure over a substrate by a sputtering method;

heating the In—

Ga—

Zn—

O based oxide semiconductor layer to form an oxide semiconductor layer including crystal grains represented by InGaZnO₄ in the amorphous structure; and

forming a channel formation region of a transistor using the oxide semiconductor layer including the crystal grains represented by InGaZnO₄,

wherein a proportion of the amorphous structure in the In—

Ga—

Zn—

O based oxide semiconductor layer is 90 volume % or less after the heating,

wherein a proportion of the crystal grains represented by InGaZnO₄ to a whole of crystal grains is 80 volume % or more.

2. The method for manufacturing the semiconductor device according to claim 1, wherein the In—

Ga—

Zn—

O based oxide semiconductor layer having the amorphous structure is formed using a target in which a Zn content by atomic percent is less than or equal to an In content by atomic percent and the Zn content by atomic percent is less than or equal to a Ga content by atomic percent.

3. The method for manufacturing a semiconductor device according to claim 1, wherein the heating is performed at 350 degrees centigrade or more.

4. The method for manufacturing a semiconductor device according to claim 1, wherein the heating is performed within a temperature from 350 to 800 degrees centigrade.

9. The method for manufacturing a semiconductor device according to claim 1 further comprising performing an oxygen radical treatment to the channel formation region of the transistor.

10. The method for manufacturing a semiconductor device according to claim 9, wherein the oxygen radical treatment is performed under an N₂O atmosphere.

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

forming an In—

Ga—

Zn—

O based oxide semiconductor layer having an amorphous structure over a substrate by a sputtering method;

heating the oxide semiconductor layer to form an oxide semiconductor layer including crystal grains represented by InGaZnO₄ in the amorphous structure; and

forming a channel formation region of a transistor using the oxide semiconductor layer including the crystal grains represented by InGaZnO₄,

wherein a proportion of the amorphous structure in the In—

Ga—

Zn—

O based oxide semiconductor layer is 90 volume % or less after the heating,

wherein a proportion of the crystal grains represented by InGaZnO₄ to a whole of crystal grains is 80 volume % or more,

wherein a Zn content by atomic percent is less than an In content by atomic percent in the In—

Ga—

Zn—

O based oxide semiconductor layer, and

wherein the Zn content by atomic percent is less than a Ga content by atomic percent in the In—

Ga—

Zn—

O based oxide semiconductor layer.

6. The method for manufacturing the semiconductor device according to claim 5, wherein the In—

Ga—

Zn—

O based oxide semiconductor layer having the amorphous structure is formed using a target in which a Zn content by atomic percent is less than or equal to an In content by atomic percent and the Zn content by atomic percent is less than or equal to a Ga content by atomic percent.

7. The method for manufacturing a semiconductor device according to claim 5, wherein the heating is performed at 350 degrees centigrade or more.

8. The method for manufacturing a semiconductor device according to claim 5, wherein the heating is performed within a temperature from 350 to 800 degrees centigrade.

11. The method for manufacturing a semiconductor device according to claim 5 further comprising performing an oxygen radical treatment to the channel formation region of the transistor.

12. The method for manufacturing a semiconductor device according to claim 11, wherein the oxygen radical treatment is performed under an N₂O atmosphere.