Methods of forming molybdenum sputtering targets
In various embodiments, sputtering targets are formed by introducing molybdenum powder into a sheet bar mold, pressing the powder to form a sheet bar, sintering the sheet bar to form an ingot having a density of at least 90% of a theoretical density, preheating the ingot, rolling the ingot to form a plate, and heat treating the plate.
1. A method of making a sputtering target, the method comprising:
introducing molybdenum powder into a sheet bar mold;
pressing the powder to form a sheet bar;
sintering the sheet bar at a first temperature to form an ingot having a density of at least 90% of a theoretical density;
preheating the ingot at a second temperature;
rolling the ingot, whereby a thickness of the ingot is reduced, to form a plate; and
heat treating the plate at a third temperature.
2. The method of claim 1 , wherein the powder is pressed at a pressure selected from the range of 100 MPa to 250 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 pressing the powder comprises cold isostatic pressing.
5. The method of claim 1 , wherein the first temperature is at least 1600° C.
6. The method of claim 1 , wherein the first temperature is selected from the range of 1600° C. to 1800° C.
7. The method of claim 1 , wherein the sheet bar is sintered for a time period of at least 4 hours.
8. The method of claim 1 , wherein the second temperature is selected from the range of 1100° C. to 1450° C.
9. The method of claim 1 , wherein the second temperature is at least 1100° C.
10. The method of claim 1 , wherein rolling the ingot comprises hot rolling the ingot at a fourth temperature.
11. The method of claim 10 , wherein the fourth temperature is selected from the range of 1050° C. to 1400° C.
12. The method of claim 10 , wherein the fourth temperature is at least 1050° C.
13. The method of claim 1 , wherein rolling the ingot reduces the thickness of the ingot by at least 50%.
14. The method of claim 1 , wherein the third temperature is selected from the range of 850° C. to 950° C.
15. The method of claim 1 , wherein the third temperature is at least 850° C.
16. The method of claim 1 , wherein the plate is heat treated for a time period of at least 30 minutes.
17. The method of claim 1 , further comprising providing the molybdenum powder by reducing ammonium dimolybdate.
18. 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.
19. The method of claim 18 , wherein an amount of the additional powder, relative to a total amount of molybdenum powder and additional powder, is at least 10 ppm.
20. The method of claim 18 , wherein an amount of the additional powder, relative to a total amount of molybdenum powder and additional powder, is approximately 1000 ppm or less.
21. The method of claim 1 , further comprising attaching at least a portion of the plate to a backing plate.
22. The method of claim 1 , wherein the plate has a texture that is substantially free of banding and substantially free of any through thickness gradient.
23. The method of claim 1 , wherein a grain size of the plate is substantially uniform.
24. The method of claim 1 , wherein an average grain size of the plate is no more than 100 μm.
25. The method of claim 1 , further comprising removing a portion from the plate, a cross-section of the portion being substantially circular or substantially cylindrical.