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P: Fachverband Plasmaphysik

P 6: Niedertemperaturplasmen, Plasmatechnologie I

P 6.7: Vortrag

Dienstag, 11. März 2008, 18:30–18:45, 2G

Electron dynamics in dual-frequency capacitively coupled RF discharges — •Julian Schulze¹, Zoltan Donko², Dirk Luggenhölscher¹, and Uwe Czarnetzki¹ — ¹Institute for Plasma and Atomic Physics, Ruhr-University Bochum — ²Hungarian Academy of Sciences, Budapest, Hungary

Particle in Cell simulations of a symmetric dual-frequency capacitively coupled RF discharge are performed in conjunction with experimental investigations of electron dynamics using Phase Resolved Optical Emission Spectroscopy [1]. In the experiment the discharge is operated at 1.94 MHz and 27.12 MHz in He-O2 with small rare gas admixture. In the simulation Helium and Argon discharges are investigated. The simulation reproduces the measured spatio-temporal excitation profiles well. It shows that the ion density in He discharges is time modulated and that the electric field in the vicinity of the electrodes is reversed at distinct phases of sheath collapse. Maximum excitation is observed at phases of collapsing low and expanding high frequency sheath, when the sheath oscillates in a region of low ion density causing a large oscillation amplitude. Depending on the operating conditions the discharge can be operated in α- or γ-mode. If it is operated in γ-mode secondary electrons dominate the ionisation, but not the excitation.

[1] J Schulze, T Gans, D O'Connell, U Czarnetzki, A R Ellingboe, M M Turner 2007 J. Phys. D 40 7008-7018

Funded by the DFG through SFB591, GRK1051, the Hungarian Scientific Research Fund (OTKA, Grants T-48389 and IN-69892) and supported by Andor Technology.