PLASMA ACTIVATED CHEMICAL VAPOUR DEPOSITION METHOD AND APPARATUS THEREFOR

摘要

In plasma activated chemical vapour deposition a plasma decomposition unit is used that is arranged in or connected to a vacuum vessel having a relatively low pressure or vacuum, to which an operating gas is provided. Periodically repeated voltage pulses are applied between the anode and the cathode of the plasma decomposition unit in such a manner that pulsed electric discharges are produced between the cathode and the surrounding anode of the plasma decomposition unit. The anode is arranged in a special way so that at least a portion thereof will obtain only an electrically conductive coating or substantially no coating when operating the unit. For that purpose, the anode includes a portion located in the direct vicinity of the free surface of the cathode. The portion is a flange or edge portion which is located or extends over margins of the free surface of the cathode. In that way, the anode will include a portion that is shielded for direct coating with particles from the plasma formed and that hence will obtain e.g. substantially no dielectric coating at all.