Atmospheric-pressure plasma processing method

Abstract

Methods for atmospheric pressure plasma discharge processing using powered electrodes having elongated planar surfaces; grounded electrodes having elongated planar surfaces parallel to and coextensive with the elongated surfaces of the powered electrodes, and spaced-apart a chosen distance therefrom, forming plasma regions, are described. RF power is provided to the at least one powered electrode, both powered and grounded electrodes may be cooled, and a plasma gas is flowed through the plasma regions at atmospheric pressure; whereby a plasma is formed in the plasma regions. The material to be processed may be moved into close proximity to the exit of the plasma gas from the plasma regions perpendicular to the gas flow, and perpendicular to the elongated electrode dimensions, whereby excited species generated in the plasma exit the plasma regions and impinge unimpeded onto the material.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the benefit of U.S. Provisional Patent Application No. 61 / 702,919 for “Atmospheric-Pressure Plasma Processing Apparatus And Method” which was filed on Sep. 19, 2012, and is a divisional of patent application Ser. No. 13 / 826,089 for “Atmospheric-Pressure Plasma Processing Apparatus And Method which was filed on Mar. 14, 2013, the entire contents of which applications are hereby specifically incorporated by reference herein for all that they disclose and teach.FIELD OF THE INVENTION[0002]The present invention relates generally to apparatus and method for plasma processing of materials and, more particularly, to an atmospheric-pressure plasma processing apparatus capable of producing a stable discharge having a neutral gas temperature that can be controlled using a cooling system, for generation of active chemical species including gas metastable and radical species effective for large area plasma processing, w...

AI Technical Summary

Benefits of technology

[0010]Accordingly, it is an object of embodiments of the present invention to provide an atmospheric-pressure plasma processing apparatus effective for producing a large area, temperature-controlled, stable plasma discharge, wherein active species generated in the plasma exit the discharge and impinge unimpeded on a material to be processed disposed outside of the discharge, but in close proximity thereto.

[0011]Another object of embodiments of the present invention is to provide an atmospheric-pressure plasma generating apparatus for producing active chemical species, wherein the plasma electrodes are cooled, thereby producing a neutral gas temperature that can be controlled.

[0012]Yet another object of embodiments of the present invention is to provide an atmospheric-pressure plasma generating apparatus effective for producing active chemical species, including gas metastables, ionic species and active physical components.

[0018]Benefits and advantages of the present invention include, but are not limited to, faster plasma processing speed resulting from an unobstructed path and a minimum distance for the excited species formed in the plasma to the material being processed. The lower neutral gas temperature, and the location of the material to be processed away from the electrical influence of the plasma, permit heat-sensitive substrates to be treated and heat-sensitive processes to be employed.

Problems solved by technology

Treatment of these substrates using vacuum-based plasmas would be complicated and prohibitively expensive.

The present state of the art for plasmas operating at or near atmospheric pressure also limits the use of plasma for treatment of these commercially-important substrates.

However, since electrical power must be transmitted through the dielectric cover, the power density that a DBD discharge can achieve is limited.

Low power density typically produces slow processing, because low-power density in the plasma also results in a slow generation rate of the active, chemical species responsible for materials processing.

Further, the metal screens cannot be water-cooled, leading to a high, neutral gas temperature (>150° C.

), especially if high rf power is used since heat removal is limited to conduction at the point of contact with the housing, and from the heat capacity of the gas as it exits the plasma.

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