Method to drive spatially separate resonant structure with spatially distinct plasma secondaries using a single generator and switching elements

• US 20030047449A1
• Filed: 10/30/2002
• Published: 03/13/2003
• Est. Priority Date: 08/11/2000
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Ramaswamy, Kartik, Hanawa, Hiroji, Collins, Kenneth S., Nguyen, Andrew, Monroy, Gonzalo Antonio
• Granted Patent: US 7,430,984 B2
• Time in Patent Office: Days
• US Class Current: 204/298.06
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge

Abstract

A plasma reactor for processing a workpiece, the plasma reactor comprising an enclosure, a workpiece support within the enclosure facing an overlying portion of the enclosure, the workpiece support and the overlying portion of the enclosure defining a process region therebetween extending generally across the diameter of said wafer support, the enclosure having a first and second pairs of openings therethrough, the two openings of each of the first and second pairs being near generally opposite sides of said workpiece support, a first hollow conduit outside of the process region and connected to the first pair of openings, providing a first torroidal path extending through the conduit and across the process region, a second hollow conduit outside of the process region and connected to the second pair of openings, providing a second torroidal path extending through the conduit and across the process region, first and second plasma source power applicators inductively coupled to the interiors of the first and second hollow conduits, respectively, each of the first and second plasma source power applicators being capable of maintaining a plasma in a respective one of the first and second torroidal paths, an RF power generator providing an RF output current, a current switching network connected between the RF power generator and the first and second plasma source power applicators for applying respective periodic time segments of RF output current to respective ones of said first and second plasma source power applicators.

Claims

1. A plasma reactor for processing a workpiece, said plasma reactor comprising:

an enclosure;

a workpiece support within the enclosure facing an overlying portion of the enclosure, said workpiece support and the overlying portion of said enclosure defining a process region therebetween extending generally across the diameter of said wafer support;

said enclosure having a first and second pairs of openings therethrough, the two openings of each of said first and second pairs being near generally opposite sides of said workpiece support;

a first hollow conduit outside of said process region and connected to said first pair of openings, providing a first torroidal path extending through said conduit and across said process region;

a second hollow conduit outside of said process region and connected to said second pair of openings, providing a second torroidal path extending through said conduit and across said process region;

first and second plasma source power applicators inductively coupled to the interiors of said first and second hollow conduits, respectively, each of said first and second plasma source power applicators being capable of maintaining a plasma in a respective one of said first and second torroidal paths;

an RF power generator providing an RF output current;

a current switching network connected between said RF power generator and said first and second plasma source power applicators for applying respective periodic time segments of RF output current to respective ones of said first and second plasma source power applicators.

2. The plasma reactor of claim 1 wherein said current switching network comprises a diode-controlled current divider.

3. The plasma reactor of claim 2 wherein said diode-controlled current divider comprises a first diode connected between said RF power generator and said first plasma source power applicator in a first diode polarity and a second diode connected between said RF power generator and said second plasma source power applicator in a second diode polarity opposite said first diode polarity.

4. The plasma reactor of claim 1 wherein said current switching network comprises respective transistor switches separately connected between said RF power generator and respective ones of said first and second plasma source power applicators and a source of mutually exclusive enabling signals controlling said respective transistor switches.

5. The plasma reactor of claim 4 wherein said enabling signals and said RF power generator are synchronized.

6. The plasma reactor of claim 1 wherein each one of said plasma source power applicators comprises an RF-driven conductive winding near the corresponding one of said first and second conduits.

7. The plasma reactor of claim 6 wherein each one of said plasma source power applicators further comprises an annular magnetic core surrounding an annular portion of the corresponding conduit, said RF-driven conductive winding being wound around a portion of said annular magnetic core.

8. The plasma reactor of claim 7 wherein each one of said plasma source power applicators further comprises a secondary conductive winding wound around another portion of said annular magnetic core and a tuning capacitor connected across said secondary winding.

9. The plasma reactor of claim 1 wherein each one of said conduits is formed of a metal material, each said conduit having an insulating gap within a wall of the conduit extending transversely to the corresponding torroidal path and separating the conduit into two portions so as to prevent formation of a closed electrical path along the length of the conduit.

10. The plasma reactor of claim 6 wherein the RF driven winding is juxtaposed along the corresponding conduit.

11. The plasma reactor of claim 1 wherein said first and second conduits are mutually transverse and wherein said first and second torroidal paths intersect in said processing region.

12. The plasma reactor of claim 11 wherein said fist and second conduits are mutually orthogonal.

13. The plasma reactor of claim 1 wherein said first and second pairs of openings are through said ceiling.

14. The plasma reactor of claim 1 further comprising a bias power RF generator coupled to said wafer support pedestal.

15. A plasma reactor for processing a workpiece, said plasma reactor comprising:

an enclosure;

a workpiece support within the enclosure facing an overlying portion of the enclosure, said workpiece support and the overlying portion of said enclosure defining a process region therebetween extending generally across the diameter of said wafer support;

an array of pairs of openings through said vacuum enclosure, the two openings of each pair being near generally opposite sides of said workpiece support;

an array of hollow conduits outside of said vacuum chamber, and connected to respective ones of said pairs of openings, whereby to provide respective closed torroidal paths for plasma, each of said respective closed torroidal paths extending outside of said vacuum chamber through a respective one of said array of conduits and extending inside said vacuum chamber between a respective pair of said openings through said process region;

respective source power applicators near respective ones of said conduits;

a source power RF generator having a cyclical current output; and

a current switching network connected between said source power RF generator and each of said respective source power applicators, for dividing each cycle of said cyclical current output into respective time segments and applying said respective time segments to respective ones of said source power applicators.

16. The plasma reactor of claim 15 wherein said current switching network comprises diode-controlled current divider.

17. The plasma reactor of claim 15 wherein said current switching network comprises respective transistor switches separately connected between said RF power generator and respective ones of said plasma source power applicators and a source of mutually exclusive enabling signals controlling said respective transistor switches.

18. The plasma reactor of claim 17 wherein said mutually exclusive enabling signals and said RF power generator are synchronized.

19. The plasma reactor of claim 15 wherein each one of said plasma source power applicators comprises an RF-driven conductive winding.

20. The plasma reactor of claim 19 wherein each one of said plasma source power applicators further comprises an annular magnetic core surrounding an annular portion of the corresponding conduit, said RF-driven conductive winding being wound around a portion of said annular magnetic core.

21. The plasma reactor of claim 20 wherein each one of said plasma source power applicators further comprises a secondary conductive winding wound around another portion of said annular magnetic core and a tuning capacitor connected across said secondary winding.

22. The plasma reactor of claim 15 wherein each one of said conduits is formed of a metal material, each said conduit having an insulating gap within a wall of the conduit extending transversely to the corresponding torroidal path and separating the conduit into two portions so as to prevent formation of a closed electrical path along the length of the conduit.

23. The plasma reactor of claim 19 wherein the RF driven winding is juxtaposed along the corresponding conduit.

24. The plasma reactor of claim 15 wherein said conduits are mutually transverse and wherein said torroidal paths intersect in said processing region.

25. The plasma reactor of claim 15 wherein said pairs of openings are through said ceiling.

26. The plasma reactor of claim 15 further comprising a bias power RF generator coupled to said wafer support pedestal.

27. The reactor of claim 15 wherein each conduit has a width along an axis parallel with the plane of said wafer support which is at least as great as the diameter of said wafer support.

28. The reactor of claim 27 wherein each conduit has a height along an axis perpendicular to the plane of said wafer support which is less than said width.

29. The reactor of claim 28 wherein each conduit has a rectangular cross-section whereby to produce a relatively thin wide belt of plasma in said closed torroidal path.

30. The reactor of claim 20 further comprising a transformer connected between said RF generator and the respective plasma source power applicators, said transformer comprising a primary winding connected across said RF generator and a secondary winding having respective portions thereof connected through said switching network across respective ones of said plasma source power applicators.

31. A plasma reactor for processing a workpiece, said plasma reactor comprising:

an enclosure;

a workpiece support within the enclosure facing an overlying portion of the enclosure, said workpiece support and the overlying portion of said enclosure defining a process region therebetween extending generally across the diameter of said wafer support;

said enclosure having at least first and second pairs of openings therethrough, the openings of each pair being near generally opposite sides of said workpiece support;

at least first and second hollow conduits outside of said process region and connected between respective ones of said first and second pairs openings, providing first and second torroidal paths extending through said conduit and across said process region;

respective plasma source power applicators near respective ones of said conduits for maintaining a plasma in each torroidal path;

a source power RF generator having a cyclical current output; and

a current switching network connected between said source power RF generator and each of said respective source power applicators, for dividing each cycle of said cyclical current output into respective time segments and applying said respective time segments to respective ones of said source power applicators;

wherein the height of said closed torroidal path along an axis generally perpendicular to a plane of said wafer support in a process region overlying said workpiece support is less than elsewhere in said closed torroidal path, whereby to enhance the plasma ion density in said process region relative to the plasma ion density elsewhere in said closed torroidal path.

32. The plasma reactor of claim 31 further comprising a conductive body between said workpiece support and said vacuum enclosure and constricting said torroidal paths in said process region overlying said wafer support.

33. The plasma reactor of claim 32 further comprising an RF bias power supply coupled to said wafer support and capable of maintaining a plasma sheath over a workpiece on said workpiece support of a thickness which constricts said torroidal paths within said process region so as to enhance plasma ion density in said process region overlying said workpiece support.

34. The plasma reactor of claim 31 wherein said conduit is formed of a metal material, said conduit having an insulating gap within a wall of the conduit extending transversely to said torroidal path and separating said conduit into two portions so as to prevent formation of a closed electrical path along the length of said conduit.

35. The plasma reactor of claim 31 wherein said vacuum enclosure comprises a longitude side wall and an overlying lateral ceiling, and wherein said first and second pairs of openings extend through said ceiling.

36. The plasma reactor of claim 32 wherein said conductive body comprises a gas distribution plate, and wherein the height of said closed torroidal path along an axis perpendicular to a plane of said wafer support is the distance between said gas distribution plate and said wafer support.

37. The plasma reactor of claim 31 wherein said current switching network comprises a diode-controlled current divider.

38. The plasma reactor of claim 31 wherein said current switching network comprises respective transistor switches separately connected between said RF power generator and respective ones of said first and second plasma source power applicators and a source of mutually exclusive enabling signals controlling said respective transistor switches.

39. The plasma reactor of claim 31 wherein each one of said plasma source power applicators comprises an RF-driven conductive winding near the corresponding one of said first and second conduits.

40. The plasma reactor of claim 39 wherein each plasma source power applicator further comprises an annular magnetic core surrounding an annular portion of the corresponding conduit, said RF-driven conductive winding being wound around a portion of said annular magnetic core.

41. The plasma reactor of claim 40 wherein each one of said plasma source power applicators further comprises a secondary conductive winding wound around another portion of said annular magnetic core and a tuning capacitor connected across said secondary winding.

42. A plasma reactor for processing a workpiece, said plasma reactor comprising:

an enclosure;

plural workpiece supports within the enclosure facing overlying portions of the enclosure, said workpiece supports and respective ones of the overlying portions of said enclosure defining respective plural process regions therebetween extending generally across the diameters of respective ones of said wafer supports;

plural arrays of pairs of openings through said vacuum enclosure, each of said arrays being generally centered around a respective one of said process regions, the two openings of each pair being near generally opposite sides of the corresponding one of said plural workpiece supports;

plural arrays of hollow conduits outside of said vacuum chamber, and connected to respective arrays of said pairs of openings, each array of hollow conduits providing a respective plurality of torroidal plasma current path through a corresponding one of said plural process regions;

respective source power applicators near respective ones of said conduits;

a source power RF generator having a cyclical current output; and

a current switching network connected between said source power RF generator and each of said respective source power applicators, for dividing each cycle of said cyclical current output into respective time segments and applying said respective time segments to respective ones of said source power applicators.

43. The plasma reactor of claim 42 wherein:

said reactor comprises a second source power RF generator having a second cyclical current output, said current switching network being connected between both source power RF generators and respective ones of said source power applicators, for dividing the cycle of the cyclical current outputs of both source power RF generators into respective time segments and applying said respective time segments to respective ones of said source power applicators;

each array of hollow conduits constitutes two hollow conduits;

each array of pairs of openings constitutes two openings; and

said current switching network comprises diode-controlled current divider.

44. The plasma reactor of claim 42 wherein said current switching network comprises respective transistor switches separately connected between said RF power generator and respective ones of said plasma source power applicators and a source of mutually exclusive enabling signals controlling said respective transistor switches.

45. The plasma reactor of claim 44 wherein said mutually exclusive enabling signals and said RF power generator are synchronized.

46. The plasma reactor of claim 42 wherein each one of said plasma source power applicators comprises an RF-driven conductive winding.

47. The plasma reactor of claim 46 wherein each one of said plasma source power applicators further comprises an annular magnetic core surrounding an annular portion of the corresponding conduit, said RF-driven conductive winding being wound around a portion of said annular magnetic core.

48. The plasma reactor of claim 47 wherein each one of said plasma source power applicators further comprises a secondary conductive winding wound around another portion of said annular magnetic core and a tuning capacitor connected across said secondary winding.

49. The plasma reactor of claim 42 wherein each one of said conduits is formed of a metal material, each said conduit having an insulating gap within a wall of the conduit extending transversely to the corresponding torroidal path and separating the conduit into two portions so as to prevent formation of a closed electrical path along the length of the conduit.