Method for forming sputtering target

• US 9,885,108 B2
• Filed: 08/01/2013
• Issued: 02/06/2018
• Est. Priority Date: 08/07/2012
• Status: Active Grant

• Current Assignee: Cintas, Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Snelting, Erin
• Application Number:
  US13/956,731
• Publication Number:
  US 20140042674A1
• Time in Patent Office: 1,650 Days
• CPC Class Codes: C01G 15/00 Compounds of gallium, indium or thallium
• 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: H01L 21/02175 characterised by the metal H01L21/02197 takes precedence
• CPC Class Codes: H01L 21/02194 the material containing more than one metal element
• CPC Class Codes: H01L 21/02266 deposition by physical ablation of a target, e.g. sputtering, reactive sputtering, physical vapour deposition or pulsed laser deposition

Abstract

To provide a sputtering target which enables an oxide film containing a plurality of metal elements and having high crystallinity. A plurality of raw materials are mixed and first baking is performed thereon, whereby a crystalline oxide is formed. The crystalline oxide is ground to form a crystalline oxide powder. The crystalline oxide powder is mixed with water and an organic substance to make slurry, and the slurry is poured into a mold provided with a filter. The water and the organic substance are removed from the slurry through the filter, so that a molded body is formed. The residual water and the residual organic substance in the molded body are removed, and then second baking is performed.

Claims

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

mixing raw materials;

forming a crystalline oxide by performing a first baking of the raw materials;

forming a crystalline oxide powder by grinding the crystalline oxide;

uniformizing particle sizes of the crystalline oxide powder by using a first sieve through which a particle with a size less than or equal to 1 μ

m passes and a second sieve through which a particle with a size less than 0.01 μ

m passes; and

then

obtaining slurry by mixing the crystalline oxide powder with water and an organic substance;

pouring the slurry into a mold provided with a filter;

removing the water and the organic substance from the slurry through the filter, thereby forming a molded body;

removing residual water and residual organic substance in the molded body by performing a heat treatment;

pressing the molded body after the heat treatment; and

then

performing a second baking of the molded body,

wherein a first step of the first baking is performed in an inert atmosphere and a second step of the first baking is performed in an oxidation atmosphere, and

wherein the second baking is performed at a higher temperature than a temperature of the heat treatment.

2. The method for forming a sputtering target according to claim 1, wherein the first baking is performed at a temperature from 1200°

C. to 1700°

C. for a period from 1 hour to 72 hours.

3. The method for forming a sputtering target according to claim 1, wherein the second baking is performed at a temperature from 1200°

C. to 1400°

C. for a period from 1 hour to 72 hours in an inert atmosphere or an oxidation atmosphere.

4. The method for forming a sputtering target according to claim 1, wherein the particle sizes of the crystalline oxide powder is made to be greater than or equal to 0.01 μ

m and less than or equal to 1 μ

m.

5. The method for forming a sputtering target according to claim 1, wherein the raw materials are an indium oxide, a gallium oxide, and a zinc oxide.

6. The method for forming a sputtering target according to claim 1, wherein the heat treatment is performed at a temperature from 300°

C. to 700°

C.

7. A method for forming a sputtering target comprising the steps of:

mixing raw materials;

forming a crystalline oxide by performing a first baking of the raw materials;

forming a crystalline oxide powder by grinding the crystalline oxide;

uniformizing particle sizes of the crystalline oxide powder by using a first sieve through which a particle with a size less than or equal to 1 μ

m passes and a second sieve through which a particle with a size less than 0.01 μ

m passes; and

then

obtaining slurry by mixing the crystalline oxide powder with water and an organic substance;

pouring the slurry into a mold provided with a filter;

removing the water and the organic substance from the slurry through the filter, thereby forming a molded body;

removing residual water and residual organic substance in the molded body, thereby providing voids in the molded body;

pressing the molded body to reduce the voids in the molded body; and

then

performing a second baking of the molded body,

wherein a first step of the first baking is performed in an inert atmosphere and a second step of the first baking is performed in an oxidation atmosphere, and

wherein the second baking is performed at a lower temperature than a temperature of the first baking.

8. The method for forming a sputtering target according to claim 7, wherein the first baking is performed at a temperature from 1200°

C. to 1700°

C. for a period from 1 hour to 72 hours.

9. The method for forming a sputtering target according to claim 7, wherein the second baking is performed at a temperature from 1200°

C. to 1400°

C. for a period from 1 hour to 72 hours in an inert atmosphere or an oxidation atmosphere.

10. The method for forming a sputtering target according to claim 7, wherein the particle sizes of the crystalline oxide powder is made to be greater than or equal to 0.01 μ

m and less than or equal to 1 μ

m.

11. The method for forming a sputtering target according to claim 7, wherein the raw materials are an indium oxide, a gallium oxide, and a zinc oxide.

12. The method for forming a sputtering target according to claim 7, wherein in the step of pressing, the molded body is pressed using a weight or compressed air.

13. A method for forming a sputtering target comprising the steps of:

mixing raw materials;

forming a crystalline oxide by performing a first baking of the raw materials;

forming a crystalline oxide powder by grinding the crystalline oxide;

uniformizing particle sizes of the crystalline oxide powder by using a first sieve through which a particle with a size less than or equal to 1 μ

m passes and a second sieve through which a particle with a size less than 0.01 μ

m passes; and

then

obtaining slurry by mixing the crystalline oxide powder with water and an organic substance;

pouring the slurry into a mold provided with a filter;

removing the water and the organic substance from the slurry through the filter, thereby forming a molded body;

removing residual water and residual organic substance in the molded body; and

pressing the molded body while performing a second baking,

wherein a first step of the first baking is performed in an inert atmosphere and a second step of the first baking is performed in an oxidation atmosphere, and

wherein the second baking is performed at a lower temperature than a temperature of the first baking.

14. The method for forming a sputtering target according to claim 13, wherein the first baking is performed at a temperature from 1200°

C. to 1700°

C. for a period from 1 hour to 72 hours.

15. The method for forming a sputtering target according to claim 13, wherein the second baking is performed at a temperature from 1200°

C. to 1400°

C. for a period from 1 hour to 72 hours in an inert atmosphere or an oxidation atmosphere.

16. The method for forming a sputtering target according to claim 13, wherein the particle sizes of the crystalline oxide powder is made to be greater than or equal to 0.01 μ

m and less than or equal to 1 μ

m.

17. The method for forming a sputtering target according to claim 13, wherein the raw materials are an indium oxide, a gallium oxide, and a zinc oxide.

18. The method for forming a sputtering target according to claim 13, wherein in the step of pressing, the molded body is pressed using a weight or compressed air.