Analytical Investigation of Plasma and Electrode Potentials in a Diode Type RF Discharge

Electrical potentials of a plasma and both electrodes in a diode type RF discharge are analytically obtained under the assumptions of quasi-static electric fields in an ion sheath, low gas pressure, charge neutrality of the plasma, and η≪1 (η is the ratio of electrode areas). The dependence of dV_pD/dU_D (V_pD and U_D are the DC part of the plasma potential and the potential difference between the plasma and the RF power electrode, respectively) on η is, then, compared with experimental results. We find the following conclusions: 1. The plasma potential does not necessarily have a simple harmonic form, even if the supplied RF power has that form. 2. The DC parts of the plasma potential and the RF power electrode potential change depending on the waveform of the supplied RF power, even if the RF amplitude and η are kept constant. 3. -dV_pD/dU_D depends quadratically on η, with a proportionality constant K which depends on the waveform of the supplied RF power.