Remote exposure of workpieces using a recirculated plasma

• US 6,406,759 B1
• Filed: 07/28/1999
• Issued: 06/18/2002
• Est. Priority Date: 01/08/1998
• Status: Expired due to Term

• Current Assignee: University of Tennessee Research Foundation (University of Tennessee)
• Original Assignee: The University Of Tennessee Research Corporation (University of Tennessee)
• Inventors: Roth, J. Reece
• Primary Examiner(s): PADGETT, MARIANNE L
• Application Number:
  US09/362,471
• Time in Patent Office: 1,056 Days
• Field of Search: 427/534, 427/535, 427/538, 427/539, 427/488, 427/491, 427/562, 427/563, 427/564, 216/71, 216/67, 134/1.1, 134/1.2
• US Class Current: 427/562
• 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, comprising the steps of:

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

(b) convecting the working gas with the one or more active species away from the plasma-generation region to a remote-exposure region containing the workpiece;

(c) subjecting the workpiece in the remote-exposure region to the one or more active species, wherein the workpiece is located outside of the plasma-generation region; and

(d) recirculating the working gas with at least one of the active species present from the remote-exposure region back to the plasma-generation region to increase concentration of the at least one of the active species in the remote-exposure region.

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

3. The method of claim 1, wherein the active species are convected away using a peristaltic EHD technique.

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

5. The method of claim 1, wherein the plasma is a self-propelled plasma and the active species are convected away using the self-propelled plasma.

6. The method of claim 1, wherein the active species are convected away by a blower.

7. The method of claim 1, wherein the working gas is air and 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 plasma conveys one or more oxidizing species of the one or more active species to the workpiece.

10. The method of claim 9, wherein the one or more oxidizing species comprise at least one of atomic oxygen, ozone, and a nitrogen oxide.

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

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

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

14. 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.

15. 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.

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

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