Apparatus and method for controlling erosion profile in hollow cathode magnetron sputter source

• US 6,193,854 B1
• Filed: 08/16/1999
• Issued: 02/27/2001
• Est. Priority Date: 01/05/1999
• Status: Expired due to Term

• Current Assignee: Novellus Systems Incorporated (LAM Research Corporation)
• Original Assignee: Novellus Systems Incorporated (LAM Research Corporation)
• Inventors: Hartsough, Larry Dowd, Ashtiani, Kaihan Abidi, Biberger, Maximilian A., Levy, Karl B., Lai, Kwok Fai, Nordquist, Andrew L.
• Primary Examiner(s): DIAMOND, ALAN D
• Application Number:
  US09/375,667
• Time in Patent Office: 561 Days
• Field of Search: 204/298.12, 204/298.16, 204/298.17, 204/298.18, 204/298.21, 204/298.22, 204/192.12, 204/192.15
• US Class Current: 204/192.12
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence
• CPC Class Codes: H01J 37/3405 Magnetron sputtering
• CPC Class Codes: H01J 37/342 Hollow targets

Abstract

A hollow cathode magnetron (HCM) sputter source includes a main magnet positioned near the sidewall of the hollow cathode target and a pair of rotating magnet arrays that are positioned near the closed end of the hollow cathode target. One of the arrays produces a magnetic field that is aligned with (aids) the magnetic field produced by the main magnet; the other arrays produce a magnetic field that is aligned against (bucks) the magnetic field produced by the main magnet. Field lines produced by the magnet arrays contain an extension of the plasma that is controlled by the main magnet. Charged particles circulate between the two portions of the plasma. The extended plasma is thus formed over a very high percentage of the surface of the target, thereby creating an erosion profile that is highly uniform and encompasses essentially the entire face of the target. This maximizes the utilization of the target and minimizes the frequency at which the spent target must be replaced.

Claims

1. A hollow cathode magnetron sputter source comprising:

a cathode target having a sidewall portion and a closed end portion, the sidewall and closed end portions of the target forming a cavity;

a main magnet positioned adjacent the sidewall portion of the target outside of the cavity, the main magnet producing a main magnetic field having field lines that extend into the cavity; and

first and second magnet arrays positioned adjacent the closed end of the target outside of the cavity and rotatable about an axis, the first magnet array being oriented to produce a magnetic field which aids the main magnetic field, the second magnet array being oriented to produce a magnetic field which bucks the main magnetic field.

2. The hollow cathode magnetron sputter source of claim 1 wherein the first and second magnet arrays are affixed to a rotatable magnet plate.

3. The hollow cathode magnetron sputter source of claim 2 wherein the first magnet array comprises a substantially uninterrupted row of magnets arranged in the form of a first arc.

4. The hollow cathode magnetron sputter source of claim 3 wherein the second magnet array comprises a substantially uninterrupted row of magnets arranged in the form of a second arc.

5. The hollow cathode magnetron sputter source of claim 4 wherein each of the first and second arcs is semicircular.

6. The hollow cathode magnetron sputter source of claim 4 wherein a radius of curvature of the first arc is the same as a radius of curvature of the second arc.

7. The hollow cathode magnetron sputter source of claim 4 wherein a radius of curvature of the first arc is different from the radius of curvature of the second arc.

8. The hollow cathode magnetron sputter source of claim 4 wherein a concave side of the first arc faces a centerpoint of the magnet plate.

9. The hollow cathode magnetron sputter source of claim 8 wherein a concave side of the second arc faces the centerpoint of the magnet plate.

10. The hollow cathode magnetron sputter source of claim 9 wherein a convex side of the second arc faces the centerpoint of the magnet plate.

11. The hollow cathode magnetron sputter source of claim 3 wherein the second magnet array comprises a plurality of magnets arranged in a radial line.

12. The hollow cathode magnetron sputter source of claim 2 wherein the magnet plate is made of a magnetic material.

13. The hollow cathode magnetron sputter source of claim 12 wherein the magnetic material comprises iron.

14. The hollow cathode magnetron sputter source of claim 2 wherein the magnet plate is made of a non-magnetic material.

15. The hollow cathode magnetron sputter source of claim 2 wherein the closed end portion of the target is flat.

16. The hollow cathode magnetron sputter source of claim 15 wherein the magnet plate is flat and parallel to the closed end portion of the target.

17. The hollow cathode magnetron sputter source of claim 16 wherein at least one of the first and second magnet arrays is movable in a radial direction with respect to the magnet plate.

18. The hollow cathode magnetron sputter source of claim 15 wherein the magnet plate is flat and not parallel to the closed end portion of the target.

19. The hollow cathode magnetron sputter source of claim 18 wherein the first and second magnet arrays are movable in a radial direction with respect to the magnet plate.

20. The hollow cathode magnetron sputter source of claim 2 wherein the magnet plate rotates about an axis which coincides with a centerpoint of the magnet plate.

21. The hollow cathode magnetron sputter source of claim 2 wherein the magnet plate rotates about an axis which is spaced apart from a centerpoint of the magnet plate.

22. The hollow cathode magnetron sputter source of claim 2 wherein the closed end portion of the target is dome-shaped and the magnet plate is also dome-shaped and parallel to the closed end portion of the target.

23. The hollow cathode magnetron sputter source of claim 2 wherein the closed end portion of the target is dome-shaped and the magnet plate is flat.

24. The hollow cathode magnetron sputter source of claim 1 wherein the first and second magnet arrays comprise permanent magnets.

25. The hollow cathode magnetron sputter source of claim 1 wherein the north pole of each of the magnets in the first magnet array faces the closed end portion of the target and the south pole of each of the magnets in the second magnet array faces the closed end portion of the target.

26. The hollow cathode magnetron sputter source of claim 1 wherein at least one of the first and second magnet arrays includes a stack of magnets.

27. The hollow cathode magnetron sputter source of claim 1 wherein at least one of the first and second magnet arrays includes a magnet on top of a nonmagnetic pedestal.

28. The hollow cathode magnetron sputter source of claim 3 wherein the first magnet array is generally located on a first side of an axis of rotation of the magnet plate and the second magnet array is generally located on a second side of an axis of rotation of the magnet plate.

29. The hollow cathode magnetron sputter source of claim 3 wherein at least one of the first and second magnet arrays is in the form of a spiral with respect to an axis of rotation of the magnet plate.

30. A hollow cathode magnetron sputter source comprising:

a cathode target having a sidewall portion and a closed end portion, the sidewall and closed end portions of the target forming a cavity;

a main magnet positioned adjacent the sidewall portion of the target outside of the cavity, the main magnet producing a main magnetic field having field lines that extend into the cavity; and

a magnet array positioned adjacent the closed end of the target outside of the cavity, the magnet array comprising a plurality of electromagnets, at least one of the magnets in the array producing a magnetic field which aids the main magnetic field, at least one other magnet in the array producing a magnetic field which bucks the main magnetic field.

31. A method of operating a hollow cathode magnetron sputter source, the sputter source comprising a cathode target having a sidewall portion and a closed end portion and forming a cavity, and a main magnet positioned adjacent the sidewall portion outside of the cavity and producing a main magnetic field that extends into the cavity, the method comprising:

providing first and second magnet arrays adjacent the closed end portion of the target and outside of the cavity, a first magnetic field produced by the first magnet array aiding the main magnetic field, a second magnetic field produced by the second magnet array bucking the main magnet field;

reducing the pressure in the sputter source;

introducing an inert gas into the sputter source;

applying a negative voltage to the target so as to create a plasma in the cavity; and

rotating the magnet arrays.

32. The method of claim 31 wherein the target is symmetrical about an axis and rotating the magnet arrays comprises rotating the magnet arrays about the axis.

33. The method of claim 32 wherein a north pole of the first magnet array faces the closed end of the target and a south pole of the second magnet array faces the closed end of the target.

34. A method of operating a hollow cathode magnetron sputter source, the sputter source comprising a cathode target having a sidewall portion and a closed end portion and forming a cavity, and a main magnet positioned adjacent the sidewall portion outside of the cavity and producing a main magnetic field that extends into the cavity, the method comprising:

providing a plurality of electromagnets adjacent the closed end portion of the target and outside of the cavity;

reducing the pressure in the sputter source;

introducing an inert gas into the sputter source;

applying a negative voltage to the target so as to create a plasma in the cavity; and

turning the electromagnets on and off in sequence to create first and second virtual rotating magnet arrays, the magnetic field produced by the first virtual rotating magnet array aiding the main magnetic field and the magnetic field produced by the second virtual rotating magnet array bucking the main magnetic field.