Methods of forming molybdenum sputtering targets
View Patent ↗In various embodiments, planar sputtering targets are produced by forming a billet at least by pressing molybdenum powder in a mold and sintering the pressed powder, working the billet to form a worked billet, heat treating the worked billet, working the worked billet to form a final billet, and heat treating the final billet.
1. A method of making a planar sputtering target comprising:
forming a billet having a diameter D 0 , the formation comprising pressing molybdenum powder in a mold and sintering the pressed powder;
working the billet to form a worked billet having a diameter D 2 smaller than D 0 ;
heat treating the worked billet;
working the worked billet to form a final billet having a diameter D f larger than D 2 ; and
heat treating the final billet.
2. The method of claim 1 , wherein the powder is pressed at a pressure selected from the range of 200 MPa to 275 MPa.
3. The method of claim 1 , wherein the powder is pressed at a pressure of at least 100 MPa.
4. The method of claim 1 , wherein pressed powder is sintered at a temperature of at least 1785° C.
5. The method of claim 1 , wherein pressed powder is sintered at a temperature selected from the range of 1785° C. to 2200° C.
6. The method of claim 1 , wherein a ratio of D 0 to D 2 is at least 3:1.
7. The method of claim 1 , wherein a ratio of D 0 to D 2 is selected from the range of 3:1 to 5:1.
8. The method of claim 1 , wherein the worked billet is heat treated at a temperature selected from the range of 800° C. to 1300° C.
9. The method of claim 1 , wherein the powder is pressed isostatically.
10. The method of claim 1 , wherein the pressed powder is sintered in hydrogen.
11. The method of claim 1 , wherein working the billet comprises extruding the billet.
12. The method of claim 11 , wherein the billet is extruded at a temperature of at least 900° C.
13. The method of claim 11 , wherein the billet is extruded at a temperature selected from the range of 925° C. to 1260° C.
14. The method of claim 1 , wherein working the billet comprises at least one of rotary forging or hammer forging.
15. The method of claim 1 , wherein the final billet is substantially recrystallized after heat treating.
16. The method of claim 1 , wherein the final billet is substantially free of strain after heat treating.
17. The method of claim 1 , wherein the final billet has an equiaxial grain structure after heat treating.
18. The method of claim 1 , wherein the final billet is heat treated at a temperature selected from the range of 1200° C. to 1400° C.
19. The method of claim 1 , wherein the worked billet is heat treated at a temperature selected from the range of 800° C. to 1000° C.
20. The method of claim 1 , wherein working the worked billet comprises upset forging the worked billet.
21. The method of claim 1 , wherein working the worked billet comprises hammer forging the worked billet.
22. The method of claim 1 , wherein the worked billet is worked at a temperature selected from the range of 800° C. to 1300° C.
23. The method of claim 1 , further comprising removing a disc-shaped portion from the final billet.
24. The method of claim 23 , wherein the disc-shaped portion is removed from a substantially cylindrical region of the final billet having an approximately constant diameter, the final billet comprising an additional region not having a constant diameter.
25. The method of claim 1 , further comprising attaching at least a portion of the final billet to a backing plate.
26. The method of claim 1 , further comprising pressing an additional powder with the molybdenum powder, the additional powder comprising at least one of tantalum, niobium, chromium, tungsten, or vanadium.
27. The method of claim 26 , wherein an amount of the additional powder, relative to a total amount of molybdenum powder and additional powder, is at least 10 ppm.
28. The method of claim 26 , wherein an amount of the additional powder, relative to a total amount of molybdenum powder and additional powder, is approximately 1000 ppm or less.