Self-consistent Monte Carlo modelling of RF plasma in a helium-like model gas

Abstract

A self-consistent modelling and simulation technique of RF nonequilibrium plasmas using a Monte Carlo method is presented. Under the condition that the product of the gas pressure and the gap length is small and/or the local electric field changes rapidly, as is commonly the case with RF plasmas, the electron energy distribution shows a nonequilibrium effect against the local electric field. The kinetics of electrons and ions is calculated by a Monte Carlo method which enables the authors to deal fully with the nonequilibrium effect. The electric field in the plasma is self-consistently determined by solving Poisson's equation. With a particle model, the statistical fluctuation tends to be large in the sheath in which the number densities of electrons and ions are low. A scaling technique which enables the authors to diminish the fluctuation, and therefore the instability of the simulation is used. The simulation method is applied to an RF plasma in an He-like model gas and the results suggest that this model can adequately simulate RF plasmas.