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P: Fachverband Plasmaphysik

P 9: Poster: Niedertemperaturplasmen

P 9.9: Poster

Tuesday, March 31, 2009, 17:30–19:30, Foyer des IfP

PIC simulations of the separate control of ion flux and energy in capacitive RF discharges via the Electrical Asymmetry Effect — Zoltan Donko¹, •Julian Schulze², Brian Heil², and Uwe Czarnetzki² — ¹Hungarian Academy of Science, Budapest, Hungary — ²Institute for Plasma and Atomic Physics, Ruhr-University Bochum

If the temporally symmetric voltage waveform applied to a capacitively coupled radio frequency (CCRF) discharge contains an even harmonic of the fundamental frequency, the sheaths in front of the two electrodes are necessarily asymmetric. A DC self bias develops even in a geometrically symmetric discharge, which is an almost linear function of the phase angle between the driving voltages. Thus, by tuning the phase, precise and convenient control of the ion energy can be achieved. In this work the EAE is verified using a Particle in Cell simulation of a geometrically symmetric dual-frequency CCRF discharge operated at 13.56 MHz and 27.12 MHz. It is shown explicitly, that the ion flux stays constant within +/- 5%, while the self bias reaches values of up to 80% of the applied voltage amplitude and the maximum ion energy is changed by a factor of three. The EAE is investigated at different pressures and electrode gaps. As geometrically symmetric discharges can be made electrically asymmetric via the EAE, the Plasma Series Resonance effect is observed for the first time in simulations of a geometrically symmetric discharge. This work is funded by the DFG through GRK 1051 and the Hungarian Scientific Research Fund through grants OTKA-T-48389 and OTKA-IN-69892.