Patent ID: 8227052
Filing Date: 2012-07-24
Classification: C23C,H01J,Y10T

Abstract:
1. A method for plasma-assisted chemical vapour deposition for coating or material removal on the inner wall of a hollow body composed of a non-metallic material, having a cross-sectional area, a longitudinal extent, and at least one opening, comprising the following steps: introducing the hollow body to be treated on its inner side into a vacuum chamber having an earthed inner side, a large-area radio-frequency electrode being arranged in the interior of the vacuum chamber, positioning the hollow body in the centre of the vacuum chamber, it being necessary to comply with a minimum distance of 15 cm on all sides between the outer wall of the hollow body and the inner wall of the vacuum chamber, introducing a gas lance comprising a tube having an internal diameter of 0.001-10 mm, a maximum external diameter of 12 mm, and a terminal nozzle having a terminal opening diameter of 0.002-6 mm, through the at least one opening into the hollow body, the gas lance being connected to a gas feed unit via a non-electrically conductive gas line, the gas lance not being earthed and not being in electrically conductive contact with the radio-frequency electrode, positioning the gas lance in the hollow body in such a way that the gas lance is positioned centrally relative to the cross section of the hollow body and the terminal nozzle of the gas lance, relative to the longitudinal extent of the hollow body, is arranged in the region of the transition from the second longitudinal third to the third longitudinal third, measured from the at least one opening of the hollow body, closing the vacuum chamber and evacuating the latter to a residual pressure of 0.001-20 pascals, introducing a working gas and also one or a plurality of reaction gases via the gas feed unit and the gas lance into the hollow body, and igniting a cavity plasma to form a plasma cloud arranged at the tip of the gas lance, by applying an electric radio-frequency field to the radio-frequency electrode.