Abstract: A plasma reactor comprises a reaction chamber having two plate-shaped electrodes arranged parallel to and above each other, whereby the substrates are supported on the lower electrode and this electrode is additionally provided with a center opening (5) through which gas is fed into the electrode space or which is evacuated from it, and where (a) the upper electrode is connected to a high frequency AC or RF voltage and (b) which has no electrode material in the regions opposite the substrates and (c) where their position and shape are determined by the substrates on the lower electrode, causing the electric field in the electrode space to be selectively weakened at at least above the substrates.