The deposition characteristics of trimethylsilane (TMS) on the electrode surface, and on floating substrates, are investigated in direct current (dc), 40 kHz, and 13.5 MHz discharges by examining the difference of dependence on operational parameters; flow rate, discharge wattage, and the system pressure. In de Slow discharge, the deposition of materials are caused by the mixture of "dark'' cathodic polymerization, which is pressure dependent, and ''glow" plasma polymerization in the negative glow, which is pressure independent. The deposition onto the cathode surface is primarily by the dark polymerization, but the deposition onto any noncathode surface, including the anode surface, is by glow plasma polymerization. The creation of reactive species occurs by electron-, ion-, and (excited neutrals)-impact dissociations of TMS in the cathode dark region and in the negative Slow. With an alternating current discharge, the feature of the dark cathodic polymerization decreases to the half of the de because an electrode is the cathode only for half of the deposition time, but in 13.5 MHz discharge, the influence of the dark cathodic polymerization totally diminishes as the creation of reactive species changes to that by the oscillating electrons and associating species in the glow. The cathodic polymerization provides the best protective coating on metallic substrates.