PLASMA TREATMENT OF SUBSTRATES

摘要

An apparatus for plasma treating a substrate comprises a high voltage source of frequency 3kHz to 30kHz connected to at least one needle electrode (11) positioned within a channel (16) inside a dielectric housing (14) having an inlet for process gas and an outlet. The channel (16) has an entry (16a) which forms the said inlet for process gas and an exit (16e) into the dielectric housing arranged so that process gas flows from the inlet through the channel (16) past the electrode (11) to the outlet of the dielectric housing. The apparatus includes means for introducing an atomised surface treatment agent in the dielectric housing, and support means (27, 28) for the substrate (25) adjacent to the outlet of the dielectric housing. The needle electrode (11) extends from the channel entry (16a) to a tip (11t) close to the exit (16e) of the channel and projects outwardly from the channel (16) so that the tip (11t) of the needle electrode is positioned in the dielectric housing close to the exit (16e) of the channel at a distance outside the channel of at least 0.5mm up to 5 times the hydraulic diameter of the channel. The channel (16) has a ratio of length to hydraulic diameter greater than 10:1.