Verification of collisionless sheath model of capacitive rf discharges by particle-in-cell simulations

Abstract

A global model for high voltage rf argon capacitive discharges in the collisionless sheath regime is verified by particle-in-cell simulations, for both current- and voltage-driven sources. The ion energy distributions (IEDs) and the IED widths are investigated and show good agreement with a theoretical model, with proper adjustment of the dc bias voltage. The sensitivities of IEDs to sources (current or voltage driven) are described. It is found that for the same variations of rf source amplitudes, larger voltage shifts are expected in the IEDs for the current-driven than the voltage-driven cases. The effects of rf frequencies on IEDs are determined for a fixed rf voltage-driven source amplitude. The IEDs show a surprising independence of the rf frequencies, which can be understood reasonably well by the combined scalings of the global discharge model and IED theoretical model.