Powder metallurgy sputtering targets and methods of producing same

• US 20060201583A1
• Filed: 05/10/2006
• Published: 09/14/2006
• Est. Priority Date: 01/07/2003
• Status: Active Grant

• Current Assignee: Christopher A. Michaluk, Global Advanced Metals, USA, Inc. (Global Advanced Metals Pty Ltd.), James Maguire, Shi Yuan
• Original Assignee: Christopher A. Michaluk, James Maguire, Shi Yuan
• Inventors: Maguire, James, Yuan, Shi, Michaluk, Christopher A.
• Granted Patent: US 7,601,296 B2
• Time in Patent Office: Days
• US Class Current: 148/237
• CPC Class Codes: B22F 1/145 Chemical treatment, e.g. passivation or decarburisation
• CPC Class Codes: B22F 2201/02 Nitrogen
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/15 Hot isostatic pressing
• CPC Class Codes: B22F 3/20 by extruding
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• CPC Class Codes: C23C 8/02 Pretreatment of the material to be coated C23C8/04 takes precedence
• CPC Class Codes: C23C 8/80 After-treatment
• CPC Class Codes: H01G 9/0525 Powder therefor
• CPC Class Codes: H01J 37/3426 Material
• CPC Class Codes: Y10T 428/12049 Nonmetal component
• CPC Class Codes: Y10T 428/12104 Particles discontinuous

Abstract

A method of forming a sputtering target and other metal articles having controlled oxygen and nitrogen content levels and the articles so formed are described. The method includes surface-nitriding a deoxidized metal powder and further includes consolidating the powder by a powder metallurgy technique. Preferred metal powders include, but are not limited to, valve metals, including tantalum, niobium, and alloys thereof.

Claims

1. A method for forming a powder metallurgy article, comprising:

surface-nitriding a deoxidized metal powder to form a surface-nitrided metal powder having an oxygen content of about 300 ppm or less and having a nitrogen content of at least about 10 ppm; and

consolidating said surface-nitrided metal powder by a powder metallurgy technique to form a metallurgical article.

2. The method of claim 1, wherein said deoxidized metal powder comprises a valve metal.

3. The method of claim 1, wherein said deoxidized metal powder comprises tantalum.

4. The method of claim 3, wherein said surface-nitrided metal powder is formed having a tantalum nitride shell.

5. The method of claim 1, wherein said deoxidized metal powder comprises niobium.

6. The method of claim 5, wherein said surface-nitrided metal powder is formed having a niobium nitride shell.

7. The method of claim 1, wherein said surface-nitrided metal powder has an oxygen content of 100 ppm or less and has a nitrogen content of at least about 40 ppm.

8. The method of claim 1, wherein said deoxidized metal powder has a mesh size of from about 40 to about 400 mesh.

9. The method of claim 1, wherein said surface-nitrided metal powder has a nitrogen content from about 100 ppm to about 1000 ppm.

10. The method of claim 1, wherein said consolidating is at a temperature not exceeding 0.7 T_H of said deoxidized metal powder.

11. The method of claim 1, wherein said consolidating comprises compressing said surface-nitrided metal powder to from about 80 to about 100% of theoretical density with compressive forces of from about 30,000 to about 90,000 psi.

12. The method of claim 1, wherein said powder metallurgy technique comprises hot isostatic pressing.

13. The method of claim 1, wherein said powder metallurgy technique comprises extrusion.

14. The method of claim 1, wherein said formed metallurgical article comprises a sputtering target.

15. The method of claim 1, wherein said surface-nitriding comprises contacting with a nitrogen gas.

16. The method of claim 1, wherein said formed metallurgical article has an oxygen content of about 300 ppm or less and has a nitrogen content of at least about 10 ppm.

17. The method of claim 1, wherein said formed metallurgical article has an oxygen content from about 1 ppm to about 100 ppm.

18. The method of claim 1, wherein said formed metallurgical article has a nitrogen content from about 40 ppm to about 10,000 ppm.

19. A method for forming a surface-nitrided metal powder, comprising:

heating a metal powder in the presence of a getter material having an affinity for oxygen that is higher than that of said metal powder;

removing said getter material from said metal powder; and

surface-nitriding said metal powder to form a surface-nitrided metal powder having an oxygen content of about 300 ppm or less and having a nitrogen content of at least about 10 ppm, wherein removing said getter material occurs before, after, or concurrently with said surface-nitriding.

20. The method of claim 19, further comprising consolidating said surface-nitrided metal powder by a powder metallurgy technique to form a metallurgical article.

21. The method of claim 20, wherein said heating is at a temperature not exceeding 0.7 T_H of said metal powder.

22. The method of claim 20, wherein said consolidating is at a temperature of about 0.7 T_H or more of said metal powder.

23. The method of claim 19, wherein said heating is at a temperature not exceeding 0.7 T_H of said metal powder.

24. The method of claim 19, wherein said heating is performed under vacuum or under an inert gas.

25. The method of claim 19, wherein said getter material comprises magnesium.

26. The method of claim 19, wherein said getter material is removed by evaporation and by chemical leaching.

27. The method of claim 19, wherein said surface-nitriding comprises contacting with a nitrogen gas.

28-62. -62. (canceled)