Plasma generator

• US 6,764,658 B2
• Filed: 01/08/2002
• Issued: 07/20/2004
• Est. Priority Date: 01/08/2002
• Status: Active Grant

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Hershkowitz, Noah, Denes, Ferencz S., Manolache, Sorin O.
• Primary Examiner(s): McDonald, Rodney G.
• Application Number:
  US10/041,378
• Publication Number:
  US 20030129107A1
• Time in Patent Office: 924 Days
• Field of Search: 422/186.04, 422/186.18, 422/186.19, 422/186.2, 422/186.29, 118/723.MP, 118/723.E, 118/723.ER, 204/298.07, 204/298.33, 156/345.29, 156/345.33, 156/345.34, 156/345.38
• US Class Current: 422/186.04
• CPC Class Codes: B29C 59/14 by plasma treatment plasma tubes per se H01J
• CPC Class Codes: H01J 37/32009 Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources plasma generation in general H05H1/24
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32532 Electrodes

Abstract

A plasma generator includes several plasma sources distributed in an array for plasma treatment of surfaces. Each plasma source includes first and second conductive electrodes. Each second electrode has a gas passage defined therein, and one of the first electrodes is situated within the gas passage in spaced relation from the second electrode, with each gas passage thereby constituting the free space for plasma generation between each pair of first and second electrodes. An insulating layer is interposed between the first and second electrodes to facilitate plasma formation via dielectric barrier discharge (DBD) in the gas passages between the first and second electrodes. The first electrodes may be provided in a monolithic structure wherein they all protrude from a common bed, and similarly the second electrodes may be monolithically formed by defining the gas passages within a common second electrode member. The first electrode bed may then be situated adjacent the second electrode member with its first electrodes extending into the gas passages. The space between the first electrode bed and the second electrode member defines a plenum space onto which the gas passages open. The plenum space, and thus the gas passages, may then be provided with process gas to generate plasma within the gas passages between the first and second electrodes. Plasma ejected from the gas passages will impinge upon and treat an adjacently-situated workpiece without the need to pass the workpiece through the gas passages, and thus the size of the workpiece to be treated is not limited by the size of the gas passages (i.e., the free space wherein plasma is generated). The ability to utilize monolithically-formed first electrodes and/or second electrodes allows for significantly denser placement of plasma sources in arrays, thereby leading to more complete plasma treatment of surfaces.

Claims

1. A plasma generator comprising:

a. several first electrodes extending from a common bed;

b. a second electrode member having several gas passages defined therein which open onto an outlet surface defined on the second electrode member,

wherein;

(1) the first electrodes are situated within the gas passages, and

(2) the second electrode member is at a different potential than the first electrodes.

2. The plasma generator of claim 1 further comprising an insulating layer interposed between the second electrode member and the first electrodes.

3. The plasma generator of claim 2 wherein the insulating layer is also provided between the second electrode member and the common bed of the first electrodes.

4. The plasma generator of claim 1 wherein each of the first electrodes extends from a base at the common bed to a tip spaced away from the common bed, and wherein at least the tip is covered by insulating material.

5. The plasma generator of claim 1 wherein the second electrode member is spaced from the first electrodes and their common bed.

6. The plasma generator of claim 1 further comprising:

a. a gas supply communicating with the gas passages of the second electrode member, and

b. a porous barrier interposed between the gas supply and the gas passages.

7. The plasma generator of claim 1 wherein the gas passages open onto a plenum space defined between the second electrode member and the common bed of the first electrodes.

8. The plasma generator of claim 7 wherein the plenum space has a porous barrier therein, the porous barrier being situated between the second electrode member and the common bed of the first electrodes.

9. The plasma generator of claim 8 further comprising a gas supply opening onto the plenum space, and wherein the opening is on the side of the porous barrier opposite the second electrode member.

10. The plasma generator of claim 1 wherein the second electrode member has an enclosed heating/cooling passage defined therein.

11. The plasma generator of claim 1 wherein the outlet surface of the second electrode member is surrounded by a ledge, whereby situating the ledge adjacent a workpiece defines a chamber between the outlet surface and the workpiece, the chamber being bounded by the outlet surface, the ledge, and the workpiece.

12. The plasma generator of claim 1 further comprising positioning means for adjusting the location of a workpiece with respect to the outlet surface of the second electrode.

13. A plasma generator comprising:

a. several first electrodes at a first potential extending from a common bed;

b. several second electrodes, each at a second potential different from the first potential, each second electrode having;

i. a gas passage defined therein which opens onto an outlet surface on the second electrode, and

ii. one of the first electrodes situated within its gas passage, this first electrode being spaced from the second electrode;

wherein the outlet surfaces of the second electrodes are adjacently arrayed along a common surface, whereby plasma generated in gas between the first and second electrodes may be ejected from the gas passages onto an article adjacent the common surface.

14. The plasma generator of claim 13 wherein the second electrodes are integrally formed within a common second electrode member, whereupon the common surface is defined.

15. The plasma generator of claim 14 further comprising a insulating layer interposed between the first and second electrodes.

16. The plasma generator of claim 15 wherein the insulating layer is also provided between the common second electrode member of the second electrodes and the common bed of the first electrodes.

17. The plasma generator of claim 14 wherein the gas passages of the second electrodes extend between the common second electrode member of the second electrodes and the common bed of the first electrodes.

18. The plasma generator of claim 13 wherein the common surface is bounded by a ledge, whereby situating the ledge adjacent a workpiece defines a chamber between the common surface, the ledge, and the workpiece.

19. The plasma generator of claim 13 farther comprising:

a. a gas supply communicating with the gas passages of the second electrodes, and

b. a porous barrier interposed between the gas supply and the gas passages.

20. The plasma generator of claim 13 further comprising positioning means for adjusting the location of a workpiece relative to the common surface whereupon the outlet surfaces of the second electrodes are arrayed.

21. A plasma generator comprising:

a. several elongated first electrodes, each extending from a base to a tip;

b. a second electrode member at a different potential than the first electrodes, each having several second electrodes defined therein, each second electrode being defined by a gas passage extending from an outlet surface on the second electrode member to an inlet surface on the second electrode member,

wherein each first electrode is situated within the gas passage of one of the second electrodes.

22. The plasma generator of claim 21 wherein an insulating layer is interposed between each first electrode and the second electrode member.

23. The plasma generator of claim 21 wherein the first electrodes have their bases extend from a common bed, the common bed being situated adjacent the inlet surface of the second electrode member.

24. The plasma generator of claim 23 further comprising a insulating layer between the first and second electrodes, and also between the inlet surface of the second electrode member and the common bed of the first electrodes.

25. The plasma generator of claim 21 wherein the outlet surface of the second electrode member is bounded by a ledge, whereby situating the ledge adjacent a workpiece defines a chamber bounded by the outlet surface, the ledge, and the workpiece.

26. The plasma generator of claim 21 further comprising positioning means for adjusting the location of a workpiece relative to the outlet surface of the second electrode member.

27. A plasma generator comprising:

a. several first electrodes extending from a common bed;

b. a second electrode having several gas passages defined therein which open onto an outlet surface defined on the second electrode; and

c. an insulating layer interposed between the second electrode and the first electrodes,

wherein the first electrodes are situated within the gas passages.

28. The plasma generator of claim 27 wherein the insulating layer is also provided between the second electrode and the common bed of the first electrodes.

29. The plasma generator of claim 27 wherein each of the first electrodes extends from a base at the common bed to a tip spaced away from the common bed, and wherein at least the tip is covered by insulating material.

30. The plasma generator of claim 27 wherein the second electrode is spaced from the first electrodes and their common bed.

31. The plasma generator of claim 27 further comprising:

a. a gas supply communicating with the gas passages of the second electrode, and

b. a porous barrier interposed between the gas supply and the gas passages.

32. The plasma generator of claim 27 wherein the gas passages open onto a plenum space defined between the second electrode and the common bed of the first electrodes.

33. The plasma generator of claim 32 wherein the plenum space has a porous barrier therein, the porous barrier being situated between the second electrode and the common bed of the first electrodes.

34. The plasma generator of claim 33 further comprising a gas supply opening onto the plenum space, and wherein the opening is on the side of the porous barrier opposite the second electrode.

35. The plasma generator of claim 27 wherein the second electrode has an enclosed heating/cooling passage defined therein.

36. The plasma generator of claim 27 wherein the outlet surface of the second electrode is surrounded by a ledge, whereby situating the ledge adjacent a workpiece defines a chamber between the outlet surface and the workpiece, the chamber being bounded by the outlet surface, the ledge, and the workpiece.

37. The plasma generator of claim 27 further comprising positioning means for adjusting the location of a workpiece with respect to the outlet surface of the second electrode.

38. The plasma generator of claim 27 wherein the second electrode is at a different potential than the first electrodes.

39. A plasma generator comprising:

a. several first electrodes extending from a common bed, wherein

(1) each of the first electrode extends from a base at the common bed to a tip spaced away from the common bed, and

(2) at least the tip is covered by insulating material;

b. a second electrode having several gas passages defined therein which open onto an outlet surface defined on the second electrode,

wherein the first electrodes are situated within the gas passages.

40. The plasma generator of claim 39 wherein the second electrode is at a different potential than the first electrodes.

41. The plasma generator of claim 39 further comprising an insulating layer interposed between the second electrode and the first electrodes.

42. The plasma generator of claim 41 wherein the insulating layer is also provided between the second electrode and the common bed of the first electrodes.

43. The plasma generator of claim 39 wherein the second electrode is spaced from the first electrodes and their common bed.

44. The plasma generator of claim 39 further comprising:

a. a gas supply communicating with the gas passages of the second electrode, and

b. a porous barrier interposed between the gas supply and the gas passages.

45. The plasma generator of claim 39 wherein the gas passages open onto a plenum space defined between the second electrode and the common bed of the first electrodes.

46. The plasma generator of claim 45 wherein the plenum space has a porous barrier therein, the porous barrier being situated between the second electrode and the common bed of the first electrodes.

47. The plasma generator of claim 46 further comprising a gas supply opening onto the plenum space, and wherein the opening is on the side of the porous barrier opposite the second electrode.

48. The plasma generator of claim 39 wherein the second electrode has an enclosed heating/cooling passage defined therein.

49. The plasma generator of claim 39 wherein the outlet surface of the second electrode is surrounded by a ledge, whereby situating the ledge adjacent a workpiece defines a chamber between the outlet surface and the workpiece, the chamber being bounded by the outlet surface, the ledge, and the workpiece.

50. The plasma generator of claim 39 further comprising positioning means for adjusting the location of a workpiece with respect to the outlet surface of the second electrode.