Different modes of a capacitively coupled radio frequency discharge in methane

Summary form only given, as follows. Two regimes of a capacitively coupled radio frequency (ccrf) discharge operating in methane are studied with a combined PIC-MCC algorithm for gas pressure P=(O.OOI-I)Torr. This new combined PICMCC approach is developed for accurate and fast simulation of a radio frequency discharge at low gas pressure and high density of plasma. The electron and ion kinetic equations (three dimensional over velocity and one dimensional in space), the transport equation for electron and ion densities and fluxes and the Poisson equation are solved selfconsistently. Both kinetic and liquid models are used during one rf cycle simulation and, therefore, the approximation of kinetic coeficients by analytical expressions is not needed. Test calculations of heating mode transition in the ccrf discharge in helium and argon showed a good agreement with experimental data. In methane ccrfdischarge the transition betwen a volume dominated mode and an active sheath mode takes place with changing the discharge current or the gas pressure. The hysteresis occurs, when the dischare current increases and decreases. A phase diagram is constructed to show the location of different discharge modes for various currents and gas pressures. We demonstrate high efficiency of the combined PIC-MCC algorithm, especially for the collisionless regime of electron heating.