Impedance matching for optimization of power transfer in a capacitively excited RF plasma reactor

In RF cold plasma reactors, energy transfer from the generator to the discharge is not perfect and only 50 to 70 percent (or even less) of the power is effectively transmitted to the discharge, the reMayning part being mostly dissipated in the matching network. The choice of this circuit is therefore the most important factor in view to optimize the energy transfer from the power supply to the plasma. Two classical networks, Π - and L -type, are analytically studied in their interaction with the experimental device. From this study, in both cases, numerical values are deduced for the coil inductance, and a capacitance range is determined for the capacitors. An experimental study in argon plasma at pressure range of 40-200 mTorr and at 13.56 MHz, performed with the two types of matching networks leads to a much effective energy transfer with the L -type, which must be chosen in order to improve the energetic yield of surface processing (sputtering or etching for instance) with a RF plasma reactor.