Sputtering target, method for manufacturing sputtering target, and method for forming thin film

• US 9,382,611 B2
• Filed: 06/05/2012
• Issued: 07/05/2016
• Est. Priority Date: 06/08/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Maruyama, Tetsunori, Imoto, Yuki, Sato, Hitomi, Watanabe, Masahiro, Mashiyama, Mitsuo, Okazaki, Kenichi, Nakashima, Motoki, Shimazu, Takashi
• Primary Examiner(s): Snelting, Erin
• Application Number:
  US13/488,626
• Publication Number:
  US 20120312681A1
• Time in Patent Office: 1,491 Days
• Field of Search: 264/653
• US Class Current: 1/1
• CPC Class Codes: B28B 11/243 Setting, e.g. drying, dehydrating or firing ceramic articles B28B11/242 takes precedence
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/76 Crystal structural characteristics, e.g. symmetry
• CPC Class Codes: C04B 35/453 based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
• CPC Class Codes: C04B 35/64 Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C23C 14/08 Oxides C23C14/10 takes precedence
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• CPC Class Codes: C23C 14/345 using substrate bias
• 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 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• 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

There have been cases where transistors formed using oxide semiconductors are inferior in reliability to transistors formed using amorphous silicon. Thus, in the present invention, a semiconductor device including a highly reliable transistor formed using an oxide semiconductor is manufactured. An oxide semiconductor film is deposited by a sputtering method, using a sputtering target including an oxide semiconductor having crystallinity, and in which the direction of the c-axis of a crystal is parallel to a normal vector of the top surface of the oxide semiconductor. The target is formed by mixing raw materials so that its composition ratio can obtain a crystal structure.

Claims

1. A method for manufacturing a sputtering target comprising the steps of:

obtaining a mixed material by mixing an InO_X raw material, a MO_Y raw material, and a ZnO_Z raw material, M being one of Ga, Sn, Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu;

forming an In-M-Zn—

O compound powder by performing a first baking to the mixed material and then grinding the mixed material;

spreading part of the In-M-Zn—

O compound powder in a mold;

forming a compound film by performing a second baking and a first pressure treatment on the part of the In-M-Zn—

O compound powder spread in the mold;

spreading another part of the In-M-Zn—

O compound powder over the compound film in the mold; and

performing a third baking and a second pressure treatment on the another part of the In-M-Zn—

O compound powder and the compound film in the mold,

wherein the first baking is performed in a first atmosphere and then in a second atmosphere,

wherein the first atmosphere is an inert atmosphere or a reduced-pressure atmosphere, and

wherein the second atmosphere is an oxidation atmosphere.

2. The method for manufacturing a sputtering target according to claim 1, wherein the In-M-Zn—

O compound powder is mixed with water, a dispersant, and a binder, and

wherein the In-M-Zn—

O compound powder is spread in the mold as a slurry.

3. The method for manufacturing a sputtering target according to claim 1, wherein a plate-like compound is obtained by increasing a thickness of the compound film until the thickness reaches a thickness comprised between 2 mm and 20 mm.

4. The method for manufacturing a sputtering target according to claim 3, wherein the plate-like compound is subjected to baking at a temperature higher than or equal to 1000°

C. and lower than or equal to 1500°

C.

5. The method for manufacturing a sputtering target according to claim 1, wherein a plate-like compound is obtained by increasing a thickness of the compound film until the thickness reaches a thickness comprised between 2 mm and 20 mm, the method further comprising:

attaching the plate-like compound to a backing plate.

6. The method for manufacturing a sputtering target according to claim 5, wherein the plate-like compound is subjected to baking at a temperature higher than or equal to 1000°

C. and lower than or equal to 1500°

C. before being attached to the backing plate.

7. The method for manufacturing a sputtering target according to claim 1, wherein the InO_X raw material, the MO_Y raw material, and the ZnO_Z raw material are mixed in a predetermined ratio, the predetermined ratio being one of 2:

2;

1, 8;

4;

3, 3;

1;

1, 1;

1;

1, 4;

2;

3, and 3;

1;

2 in a molar ratio, and M being one of Sn, Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

8. The method for manufacturing a sputtering target according to claim 1, wherein the InO_X raw material, the MO_Y raw material, and the ZnO_Z raw material are mixed in a predetermined ratio, the predetermined ratio being one of 2:

2;

1, 8;

4;

3, 3;

1;

1, 1;

1;

1, 4;

2;

3, and 3;

1;

2 in a molar ratio, and M being Ga.

9. A method for manufacturing a sputtering target comprising the steps of:

obtaining a mixed material by mixing an InO_X raw material, a MO_Y raw material, and a ZnO_Z raw material, M being one of Ga, Sn, Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu;

forming an In-M-Zn—

O compound powder by performing a first baking to the mixed material and then grinding the mixed material;

spreading part of the In-M-Zn—

O compound powder in a mold;

forming a compound film by performing a second baking and a first pressure treatment on the part of the In-M-Zn—

O compound powder spread in the mold;

spreading another part of the In-M-Zn—

O compound powder over the compound film in the mold; and

performing a third baking and a second pressure treatment on the another part of the In-M-Zn—

O compound powder and the compound film in the mold,

wherein the second baking is performed in a first atmosphere and then in a second atmosphere,

wherein the first atmosphere is an inert atmosphere or a reduced-pressure atmosphere, and

wherein the second atmosphere is an oxidation atmosphere.

10. The method for manufacturing a sputtering target according to claim 9, wherein the In-M-Zn—

O compound powder is mixed with water, a dispersant, and a binder, and

wherein the In-M-Zn—

O compound powder is spread in the mold as a slurry.

11. The method for manufacturing a sputtering target according to claim 9, wherein a plate-like compound is obtained by increasing a thickness of the compound film until the thickness reaches a thickness comprised between 2 mm and 20 mm.

12. The method for manufacturing a sputtering target according to claim 11, wherein the plate-like compound is subjected to baking at a temperature higher than or equal to 1000°

C. and lower than or equal to 1500°

C.

13. The method for manufacturing a sputtering target according to claim 9, wherein a plate-like compound is obtained by increasing a thickness of the compound film until the thickness reaches a thickness comprised between 2 mm and 20 mm, the method further comprising:

attaching the plate-like compound to a backing plate.

14. The method for manufacturing a sputtering target according to claim 13, wherein the plate-like compound is subjected to baking at a temperature higher than or equal to 1000°

C. and lower than or equal to 1500°

C. before being attached to the backing plate.

15. The method for manufacturing a sputtering target according to claim 9, wherein the InO_X raw material, the MO_Y raw material, and the ZnO_Z raw material are mixed in a predetermined ratio, the predetermined ratio being one of 2:

2;

1, 8;

4;

3, 3;

1;

1, 1;

1;

1, 4;

2;

3, and 3;

1;

2 in a molar ratio, and M being one of Sn, Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

16. The method for manufacturing a sputtering target according to claim 9, wherein the InO_X raw material, the MO_Y raw material, and the ZnO_Z raw material are mixed in a predetermined ratio, the predetermined ratio being one of 2:

2;

1, 8;

4;

3, 3;

1;

1, 1;

1;

1, 4;

2;

3, and 3;

1;

2 in a molar ratio, and M being Ga.