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P: Fachverband Plasmaphysik

P II: Poster: Niedertemperaturplasmen, Plasmatechnologie

P II.15: Poster

Dienstag, 11. März 2008, 11:00–13:00, Poster C3

Electron heating in asymmetric capacitively coupled RF discharges at low pressures — •J Schulze¹, B Heil¹, D Luggenhölscher¹, T Mussenbrock², R P Brinkmann², and U Czarnetzki¹ — ¹Institute for Plasma and Atomic Physics, Ruhr-University Bochum — ²Institute for Theoretical Electrical Engineering, Ruhr-University Bochum

Despite its enormous relevance for applications, the phenomenon of stochastic electron heating in capacitively coupled RF discharges is not fully understood. A detailed experimental and theoretical investigation of electron heating in such discharges is performed at low pressures (< 10 Pa). Various diagnostics in combination with analytical models and numerical simulations are applied: The electric field in the sheath is measured space and time resolved by Fluorescence Dip Spectroscopy in Krypton. The excitation is investigated using Phase Resolved Optical Emission Spectroscopy. Radially resolved Langmuir probe measurements of electron density, mean energy and energy distribution function are performed. RF voltage and current waveform are measured. The measured electric fields are compared with the results of a fluid sheath model. The spatio-temporal excitation is calculated by a hybrid Monte Carlo simulation. The RF current at low pressures is non-sinusoidal due to the Plasma Series Resonance (PSR), but well described by an analytical model. The generation of energetic electron beams during sheath expansion is observed and described by another analytical model. It is concluded that stochastic heating is closely related to electron beams and the PSR effect.