Erlangen 2018 – scientific programme

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P: Fachverband Plasmaphysik

P 6: Codes and Modelling

P 6.2: Talk

Monday, March 5, 2018, 16:45–17:00, KI 1.174

Impedance modeling for DF-plasmas where one of the frequencies is well below the ion plasma frequency — •Jan Kuhfeld¹, Yukinori Sakiyama², and Uwe Czarnetzki¹ — ¹Institute for Plasma and Atomic Physics, Ruhr-University Bochum, Germany — ²Lam Research Corporation, 11361 SW Leveton Dr, Bldg. C, Tualatin OR 97062, USA

For industrial applications, e.g. plasma enhanced chemical vapor deposition (PECVD), dual frequency (DF) plasmas are used to gain a better control over important plasma parameters. In contrast to traditional DF discharges where both frequencies are in the MHz range, here the lower frequency is 400 kHz and well below the ion plasma frequency. This means that the ion sheath dynamics play an important role and cannot be neglected. Additionally PECVD reactors are operated at pressures of a few hundred Pa, so that secondary electrons have to be considered as well. Measurements for this case show a typical capacitively dominated impedance for the high frequency voltage (13.56 MHz) while the behavior of the low frequency current is of a resistive nature. Here, this phenomenon is investigated with a fluid simulation and a simple analytical model is developed for a better understanding of the underlying physics.