Abstract: An ECR plasma CVD apparatus is used for forming a silicon oxide film on a semiconductor substrate. The gas pressure inside the apparatus is set within the range of 7.times.10.sup.-3 to 1.times.10.sup.-1 Tort and high frequency power is applied to the substrate. A cusp-shaped magnetic field is created. Due to a synergistic effect between the high frequency electric field and the cusp-shaped magnetic field, the film has an improved waterproofing property. The gas pressure inside the apparatus is controlled by controlling the cross sectional area of a bypassing conduit connected to an exhaust pipe, by introducing gas into the exhaust pipe in a central portion thereof, or by controlling the rotational speed of a vacuum pump.

Abstract: A method and apparatus for a reactive treatment of the surface of a workpiece, in which a process gas is brought into a chamber and a direct voltage arc discharge is generated in the chamber, the arc discharge is assisted or maintained, respectively by a coupling in of a flow of charged particles. In known treatment methods plasma generated in the direct voltage arc are generally distributed inhomogeneously in the inner space of the chamber and the area with a density of the plasma which is sufficient for the reactive surface treatment is relatively small. According to the invention this problem is solved in that the distribution of the effect of the treatment of the plasma in the chamber at least along a predetermined plane is set, and specifically by a setting of an areal distribution of the process gas inlet and/or setting of an areal distribution of the arc discharges in the chamber, in that the flow of charged particles is coupled into the chamber via a plurality of distribution openings.