PLASMA COMPONENT FILTERING THROUGH A HOLE USING THE SHEATH GENERATED AROUND THE HOLE ON SURFACE MODIFICATION BY RF PLASMA

Glassy carbon (GC) surfaces were subjected to RF glow-discharged plasm a treatment through a simple filter comprising of an aluminum plate wi th an aperture at the center. Surface properties were estimated by con tact angle measurement and the atomic ratio O/C obtained from X-ray ph otoelectron spectroscopy (XPS). When the aperture was small enough (2r < 1 mm), the properties of the GC surface did not alter with the Ar p lasma treatment. Ar ions could not pass through the hole. The surface properties under the hole were changed when 2r was 5 mm, suggesting th e acceleration of the Ar ions to the GC surface as a result of the ele ctric field in the sheath. There is a threshold value for aperture siz e above which the ions can pass through. On the other hand, the proper ties of the GC surface were changed almost uniformally after O-2 plasm a treatment with a small aperture size (2r < 1 mm). O-2 plasma compone nts travelled to the interior of the sample. It is considered that the radicals mainly acted because they are neutral and uninfluenced by th e electric held in the sheath. Radicals in the O-2 plasma moved by ran dom walk and could reach the interior of the sample. With 2r of 5 mm, the surface under the hole was mainly changed by ion-assisted reaction s.