Remote exposure of workpieces using a plasma

• US 20030029566A1
• Filed: 05/28/2002
• Published: 02/13/2003
• Est. Priority Date: 01/08/1998
• Status: Active Grant

• Current Assignee: The University Of Tennessee Research Corporation (University of Tennessee)
• Original Assignee: The University Of Tennessee Research Corporation (University of Tennessee)
• Inventors: Roth, J. Reece
• Granted Patent: US 6,676,802 B2
• Time in Patent Office: Days
• US Class Current: 156/345.35
• CPC Class Codes: A61L 2/14 Plasma, i.e. ionised gases
• CPC Class Codes: B29C 59/14 by plasma treatment plasma tubes per se H01J
• CPC Class Codes: C23C 16/452 by activating reactive gas streams before their introduction into the reaction chamber, e.g. by ionisation or addition of reactive species
• CPC Class Codes: H01J 2237/336 Changing physical properties of treated surfaces
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32366 Localised processing
• CPC Class Codes: H05H 1/24 Generating plasma nuclear fusion reactors G21B1/00; gas-filled discharge reactors H01J37/32
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence
• CPC Class Codes: H05H 1/466 using capacitive coupling means, e.g. electrodes
• CPC Class Codes: H05H 2240/10 at atmospheric pressure
• CPC Class Codes: H05H 2240/20 Non-thermal plasma
• CPC Class Codes: H05H 2245/40 Surface treatments
• CPC Class Codes: H05H 2277/14 Portable devices

Abstract

An OAUGD plasma is generated using, for example, paraelectric or peristaltic electrohydrodynamic (EHD) techniques, in the plasma generator of a remote-exposure reactor, wherein one or more active species, especially oxidizing species in the plasma are convected away from the plasma-generation region and directed towards a workpiece that is located outside of the plasma-generation region (e.g., within an optional remote-exposure chamber configured to the plasma generator). In this way, the workpiece can be subjected to the one or more active species without directly being subjected to either the plasma or to the electric fields used to generate the plasma. The plasma generator may have a set of flat panels arranged within an air baffle to convect the active species in a serpentine manner through the plasma generator. The remote-exposure reactor can also be configured as a portable backpack unit with tubing that is used to direct the active species onto the workpiece, rather than placing the workpiece within a remote-exposure chamber of the reactor.

Claims

1. A method for treating a workpiece with one or more active species from a plasma, comprising the steps of:

(a) applying power to generate an electric field within a plasma-generation region to generate a one atmosphere uniform glow discharge OAUGD plasma;

(b) convecting the one or more active specie(s) away from the plasma-generation region to the workpiece; and

(c) subjecting the workpiece to the one or more active specie(s), wherein the workpiece is located outside of the plasma-generation region such that the workpiece is not directly subjected to the plasma or to the electric field within the plasma-generation region.

2. The method of claim 1, wherein the active specie(s) are convected away using a paraelectric electrohydrodynamic (EHD) technique.

3. The method of claim 1, wherein the active specie(s) are convected away using a peristaltic EHD technique.

4. The method of claim 1, wherein the active specie(s) are convected away using a DC mobility drift technique.

5. The method of claim 1, wherein the active specie(s) are convected away using a self-propelled plasma.

6. The method of claim 1, wherein the active specie(s) are convected away by a blower.

7. The method of claim 1, wherein the plasma is generated in air at one atmosphere.

8. The method of claim 1, wherein the plasma is generated at room temperature.

9. The method of claim 1 wherein the self-propelled plasma conveys oxidizing species with a low heat flux to the workpieces.

10. The method of claim 1 wherein the oxidizing species are atomic oxygen, ozone, or nitrogen oxides.

11. The method of claim 1, wherein the power is applied to one or more plasma panels located within the plasma-generation region.

12. The method of claim 9, wherein each plasma panel comprises a dielectric substrate with an array of strip electrodes on one side of the substrate and a sheet electrode on another side of the substrate.

13. The method of claim 9, wherein each plasma panel comprises a dielectric substrate with a first array of strip electrodes on one side of the substrate and a second array of strip electrodes on another side of the substrate, wherein the strip electrodes of the first array are positioned asymmetrically with respect to the strip electrodes of the second array.

14. The method of claim 1, wherein the method is used to sterilize or decontaminate the workpiece.

15. The method of claim 1, wherein the workpiece comprises one or more electronic components and the method is used to treat the one or more electronic components.

16. The method of claim 1, wherein the workpiece is a film or fabric and the method is used to change one or more surface characteristics of the film or fabric.

17. The method of claim 1, wherein the method is used to perform plasma chemical vapor deposition on the workpiece.

18. The method of claim 1, wherein the method is used to perform plasma etching on the workpiece.

19. A remote-exposure reactor, comprising:

(a) a plasma generator defining a plasma-generation region and having one or more plasma panels adapted to be configured to a power supply to generate an OAUGD plasma within the plasma-generation region, wherein one or more active specie(s) of the plasma are convected away from the plasma-generation region to the workpiece by conveying away means; and

(b) means for subjecting a workpiece located outside of the plasma-generation region to the one or more active specie(s) such that the workpiece is not directly subjected to the plasma or to the electric field within the plasma-generation region.

20. The reactor of claim 19, wherein the convection away of the plasma past the panels is by using a paraelectric EHD technique.

21. The reactor of claim 19, wherein the convection away of the plasma past the panels is by using a peristaltic EH) technique.

22. The reactor of claim 19, wherein the convection away of the plasma past the panels is by using a DC mobility drift technique.

23. The reactor of claim 19, wherein the convection away of the plasma past the panels is by a self-propelled plasma.

24. The reactor of claim 19, wherein the convection away from the plasma generating region by a blower means.

25. The reactor of claim 19, wherein the plasma is generated in air at one atmosphere.

26. The reactor of claim 19, wherein the active species are oxidizing species carried within a low heat flux of the plasma.

27. The reactor of claim 26, wherein the active species are atomic oxygen, ozone or nitrogen oxides.

28. The reactor of claim 20, wherein the plasma is a one-atmosphere uniform glow discharge plasma.

29. The reactor of claim 19, wherein each plasma panel comprises a dielectric substrate with an array of strip electrodes on one side of the substrate and a sheet electrode on another side of the substrate.

30. The reactor of claim 19, wherein each plasma panel comprises a dielectric substrate with a first array of strip electrodes on one side of the substrate and a second array of strip electrodes on another side of the substrate, wherein the strip electrodes of the first array are positioned asymmetrically with respect to the strip electrodes of the second array.

31. The reactor of claim 19, further comprising a blower means to assist in convecting the one or more active species away from the plasma-generation region.

32. The reactor of claim 19, wherein the plasma generator comprises a plurality of plasma panels configured in an air baffle such that the one or more active species are convected in a serpentine manner through the plasma-generation region.

33. The reactor of claim 19, wherein means (b) comprises a remote-exposure chamber configured to receive the one or more active species that are convected away from the plasma-generation region and adapted to hold the workpiece, whereby the workpiece is subjected to the one or more active species within the remote-exposure chamber.

34. The reactor of claim 33, further comprising tubing configured to supply gas to the plasma-generation region and to remove gas from the remote-exposure chamber.

35. The reactor of claim 34, wherein the tubing is configured with one or more valves to control whether the gas removed from the remote-exposure chamber is recirculated back through the gas-generation region or exhausted from the remote-exposure reactor.

36. The reactor of claim 19, wherein means (b) comprises tubing configured to receive the one or more active species that are convected away from the plasma-generation region and to direct the one or more active species onto the workpiece.

37. The reactor of claim 34, wherein the remote-exposure reactor is configured as a portable backpack unit and the tubing comprises a hand-held wand for directing the one or more active species onto the workpiece.