Method for making W/Ti sputtering targets and products in an inert atmosphere

• US 5,993,734 A
• Filed: 03/25/1998
• Issued: 11/30/1999
• Est. Priority Date: 03/25/1998
• Status: Expired due to Fees

• Current Assignee: Praxair S.T. Technology, Inc. (Linde Plc)
• Original Assignee: Materials Research Corporation (Linde Plc), Sony Corporation (Sony Group Corp.)
• Inventors: Hunt, Thomas J., Snowman, Alfred
• Primary Examiner(s): Jenkins, Daniel J.
• Application Number:
  US09/047,849
• Time in Patent Office: 615 Days
• Field of Search: 419/48, 419/54, 419/57, 75/248
• US Class Current: 419/48
• CPC Class Codes: B22F 2201/10 Inert gases
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/1017 Multiple heating or additional steps B22F3/101 takes precedence
• CPC Class Codes: B22F 3/14 simultaneously
• CPC Class Codes: B22F 9/023 Hydrogen absorption
• CPC Class Codes: B22F 9/04 starting from solid material, e.g. by crushing, grinding or milling C22C1/1084 takes precedence; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy

Abstract

The invention relates to the manufacture of sputtering targets of tungsten-titanium alloy using high purity tungsten and titanium hydride powders. The powders are blended and placed in a containment vessel holding a die. The die is heated to a temperature of about 700° C. to about 1000° C. in an argon atmosphere while under pressure. The combination of temperature and pressure is high enough to dehydrate the titanium hydride and to remove the gases. The die is then heated to a higher temperature, in the range of about 1250° C. to 1350° C. while the pressure is increased so as to compact and alloy the powders. The pressure and temperature are held constant until there is no further movement of the ram. The resulting compacted alloy material is then machined to provide a sputtering target with a density between 96% and 100% of theoretical and a gas content less than 850 p.p.m. In a further feature of the present invention, a tungsten-titanium hydride powder may be used as the raw material for manufacturing the target. The raw materials of the present invention may be obtained by recycling used titanium targets or used tungsten-titanium targets.

Claims

1. A method for the manufacture of W/Ti sputtering targets comprising the steps of:

placing a W powder and a TiH₂ powder in a container located in an inert gas atmosphere;

blending the W powder and the TiH₂ powder to form a blended powder;

reducing the particle size of the blended powder to approximately 150 μ

m or less;

placing the blended powder in a die held within a containment vessel having a ram, and purging the vessel with an inert gas flow;

subjecting the blended powder to a containment pressure of about 1.3 to 4.2 MPa;

subjecting the containment vessel, die and blended powder, while continuing the inert gas flow, to a first heat/pressure cycle consisting of applying a first pressure of about 6.8 to 25 MPa to the blended powder and heating to a first temperature of about 1250°

C. to about 1350°

C., followed by cooling to room temperature;

subjecting the containment vessel, die and blended powder, while continuing the inert gas flow, to a second heat/pressure cycle consisting of a second temperature and a second pressure sufficient to dehydrate the TiH₂ and to remove any other gases, forming a dehydrated blended powder;

subjecting the containment vessel, die and dehydrated blended powder, while continuing the inert gas flow, to a third heat/pressure cycle consisting of heating the die to a third temperature higher than said second temperature, and concurrently increasing the pressure to a third pressure higher than said second pressure so as to compact and alloy the dehydrated blended powder; and

releasing the third pressure, cooling the containment vessel to room temperature, and subsequently stopping the inert gas flow.

2. The method of claim 1, wherein the container is a blending can.

3. The method of claim 1, wherein the blending is a turbulent blending procedure.

4. The method of claim 1, wherein the blending is performed for 1 to 4 hours.

5. The method of claim 1, wherein the inert gas is argon.

6. The method of claim 1, wherein the particle size of the blended powder is reduced to 50 μ

m or less.

7. The method of claim 1, wherein reducing the particle size is accomplished by ball milling in a ball mill jar.

8. The method of claim 7, wherein the ball milling is performed for at least 4 hours.

9. The method of claim 1, wherein the die is made up of graphite die components that have been vacuum annealed.

10. The method of claim 1, wherein the containment pressure is 2.75 MPa.

11. The method of claim 1, wherein the second heat/pressure cycle consists of heating the die to a second temperature of about 700°

C. to 1000°

C. and applying a second pressure of about 6.8 to 11 MPa, wherein the combination of the second temperature and the second pressure is sufficient to dehydrate the TiH₂ and to remove any other gases.

12. The method of claim 1, wherein the second heat/pressure cycle is maintained for about 2 hours or more.

13. The method of claim 1, wherein the third heat/pressure cycle is maintained until there is no further movement of the ram.

14. The method of claim 13, wherein the third heat/pressure cycle is maintained for at least 7 hours.

15. The method of claim 1, wherein the third pressure is about 40 to 11 to 16.5 MPa.

16. The method of claim 1, wherein the third temperature is in the range of 1250°

C. to 1350°

C.

17. A W/Ti sputtering target manufactured by the method of claim 1 having a density of greater than 95% theoretical and a gas content of less than 850 p.p.m.

18. A method for the manufacture of W/Ti sputtering targets comprising the steps of:

placing a W powder and a TiH₂ powder in a first container held inside a chamber having an argon atmosphere;

blending the W powder and the TiH₂ powder for about 1 to 4 hours to form a blended powder;

transferring the blended powder within the chamber to a second container containing a predetermined amount of ball mill media and ball milling the blended powder for a time sufficient to reduce the particle size of the blended powder to about 50 μ

m or less;

placing the blended powder in a die held within a containment vessel having a ram, and purging the vessel with an argon flow;

subjecting the blended powder to a containment pressure of about 1.3 to 4.2 MPa;

subjecting the containment vessel, die and blended powder, while continuing the argon flow, to a first heat/pressure cycle consisting of applying a first containment pressure of about 6.8 to 25 MPa to the blended powder and heating to a first temperature of about 1250°

C. to 1350°

C., followed by cooling to room temperature;

subjecting the containment vessel, die and blended powder, while continuing the argon flow, to a second heat/pressure cycle consisting of heating the die to a second temperature of about 700°

C. to 1000°

C. and applying a second pressure of about 6.8 to 11 MPa, wherein the combination of the second temperature and second pressure is sufficient to dehydrate the TiH₂ and to remove any other gases, forming a dehydrated blended powder;

maintaining a second temperature and second pressure for about 2 hours or more;

subjecting the containment vessel, die and dehydrated blended powder, while continuing the argon flow, to a third heat/pressure cycle consisting of heating the die to a third temperature in the range of 1250°

C. to 1350°

C. and concurrently increasing the pressure to a third pressure of about 11 to 16.5 MPa so as to compact and alloy the dehydrated blended powder;

maintaining a third temperature and third pressure until there is no further movement of the ram; and

releasing the third pressure, cooling the containment vessel to room temperature and subsequently stopping the argon flow.

19. The method of claim 18, wherein the first container is a blending can.

20. The method of claim 18, wherein the blending is a turbulent blending procedure.

21. The method of claim 18, wherein amount of ball mill media is approximately equal to the amount of blended powder.

22. The method of claim 18, wherein the ball milling is performed for at least 4 hours.

23. The method of claim 18, wherein the die is made up of graphite die components that have been vacuum annealed.

24. The method of claim 18, wherein the third heat/pressure cycle is maintained for at least 7 hours.

25. A W/Ti sputtering target manufactured by the method of claim 18 having a density of greater than 95% theoretical and a gas content of less than 850 p.p.m.

26. A method for the manufacture of W/Ti sputtering targets comprising the steps of:

placing a W-TiH₂ powder in a chamber having an inert gas atmosphere;

reducing the particle size of the W-TiH₂ powder to 150 μ

m or less;

placing the W-TiH₂ powder in a die held within a containment vessel having a ram, and purging the vessel with an inert gas flow;

subjecting the W-TiH₂ powder to a containment pressure of about 1.3 to 4.2 MPa;

subjecting the containment vessel, die and W-TiH₂ powder, while continuing the inert gas flow, to a first heat/pressure cycle consisting of applying a first pressure of about 6.8 to 25 MPa to the W-TiH₂ powder and heating to a first temperature of about 1250°

C. to 1350°

C., followed by cooling to room temperature;

subjecting the containment vessel, die and W-TiH₂ powder, while continuing the inert gas flow, to a second heat/pressure cycle consisting of a second temperature and a second pressure sufficient to dehydrate the W-TiH₂ powder and to remove any other gases, forming a W-Ti powder;

subjecting the containment vessel, die and W-Ti powder, while continuing the inert gas flow, to a third heat/pressure cycle consisting of heating the die to a third temperature higher than said second temperature, and concurrently increasing the pressure to a third pressure higher than said second pressure so as to compact and alloy the W-Ti powder; and

releasing the third pressure, cooling the containment vessel to room temperature and subsequently stopping the inert gas flow.

27. The method of claim 26, wherein the inert gas is argon.

28. The method of claim 26, wherein the particle size of the blended powder is reduced to 50 μ

m or less.

29. The method of claim 26, wherein reducing the particle size is accomplished by ball milling in a ball mill jar.

30. The method of claim 29, wherein the ball milling is performed for at least 4 hours.

31. The method of claim 26, wherein the die is made up of graphite die components that have been vacuum annealed.

32. The method of claim 26, wherein the containment pressure is 2.75 MPa.

33. The method of claim 26, wherein the second heat/pressure cycle consists of heating the die to a second temperature of about 700°

C. to 1000°

C. and applying a second pressure of about 6.8 to 11 MPa, wherein the combination of the second temperature and the second pressure is sufficient to dehydrate the TiH₂ and to remove any other gases.

34. The method of claim 26, wherein the second heat/pressure cycle is maintained for about 2 hours or more.

35. The method of claim 26, wherein the third heat/pressure cycle is maintained until there is no further movement of the ram.

36. The method of claim 35, wherein the third heat/pressure cycle is maintained for at least 7 hours.

37. The method of claim 26, wherein the third pressure is about 11 to 16.5 MPa.

38. The method of claim 26, wherein the third temperature is in the range of 1250°

C. to 1350°

C.

39. A W/Ti sputtering target manufactured by the method of claim 26 having a density of greater than 95% theoretical and a gas content of less than 850 p.p.m.

40. A method for the manufacture of W/Ti sputtering targets comprising the steps of:

placing a W-TiH₂ powder in a container held inside a chamber having an argon atmosphere, said container containing a predetermined amount of ball mill media;

ball milling the W-TiH₂ powder for a time sufficient to reduce the particle size of the W-TiH₂ powder to about 50 μ

m or less;

placing the W-TiH₂ powder in a die held within a containment vessel having a ram, and purging the vessel with an argon flow;

subjecting the W-TiH₂ powder to a containment pressure of about 1.3 to 4.2 MPa;

subjecting the containment vessel, die and W-TiH₂ powder, while continuing the argon flow, to a first heat/pressure cycle consisting of applying a first pressure of about 1.3 to 4.2 MPa to the blended powder and heating to a first temperature of about 1250°

C. to 1350°

C., followed by cooling to room temperature;

subjecting the containment vessel, die and W-TiH₂ powder, while continuing the argon flow, to a second heat/pressure cycle consisting of heating the die to a second temperature of about 700°

C. to 1000°

C. and applying a second pressure of about 6.8 to 11 MPa, wherein the combination of the second temperature and second pressure is sufficient to dehydrate the TiH₂ and to remove any other gases, forming a W-Ti powder;

maintaining a second temperature and second pressure for about 2 hours or more;

subjecting the containment vessel, die and W-Ti powder, while continuing the argon flow, to a third heat/pressure cycle consisting of heating the die to a third temperature in the range of 1250°

C. to 1350°

C. and concurrently increasing the pressure to a third pressure of about 11 to 16.5 MPa so as to compact and alloy the W-Ti powder;

maintaining a third temperature and third pressure until there is no further movement of the ram; and

releasing the third pressure, cooling the containment vessel to room temperature and subsequently stopping the argon flow.

41. The method of claim 40, wherein amount of ball mill media is approximately equal to the amount of W-TiH₂ powder.

42. The method of claim 40, wherein the ball milling is performed for at least 4 hours.

43. The method of claim 40, wherein the die is made up of graphite die components that have been vacuum annealed.

44. The method of claim 40, wherein the third heat/pressure cycle is maintained for at least 7 hours.

45. A W/Ti sputtering target manufactured by the method of claim 40 having a density of greater than 95% theoretical and a gas content of less than 850 p.p.m.