Powder metallurgy sputtering targets and methods of producing same
View Patent ↗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.
1. 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 100 ppm, wherein removing said getter material occurs before, after, or concurrently with said surface-nitriding, and consolidating said surface-nitrided metal powder by a powder metallurgy technique to form a metallurgical article, wherein said metallurgical article is a sputter target.
2. The method of claim 1 , wherein said heating is at a temperature not exceeding 0.7 T H of said metal powder.
3. The method of claim 1 , wherein said consolidating is at a temperature of about 0.7 T H or more of said metal powder.
4. The method of claim 1 , wherein said heating is at a temperature not exceeding 0.7 T H of said metal powder.
5. The method of claim 1 , wherein said heating is performed under vacuum or under an inert gas.
6. The method of claim 1 , wherein said getter material comprises magnesium.
7. The method of claim 1 , wherein said getter material is removed by evaporation and by chemical leaching.
8. The method of claim 1 , wherein said surface-nitriding comprises contacting with a nitrogen gas.
9. The method of claim 1 , wherein said metal powder for said surface-nitriding is valve metal powder having a mesh size of from between about 40 mesh to about 400 mesh.
10. The method of claim 1 , wherein said metal powder for said surface-nitriding is valve metal powder having a mesh size of from between about 40 mesh to about 100 mesh.