Hannover 2010 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 8: Poster: Low Temperature Plasmas I
P 8.5: Poster
Dienstag, 9. März 2010, 16:00–18:00, Lichthof
Analysis of CF radical kinetics in pulsed fluorocarbon rf plasmas (CCP) — •Sergey Stepanov and Jürgen Meichsner — Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17487 Greifswald, Germany
Measurements of the absolute number density of the highly reactive CF radical have shown a fast kinetics of the species in low pressure CF4+H2 capacitively coupled 13.56 MHz plasmas pulsed with a frequency of <1Hz [1]. Under considered plasma conditions, the total decay of the radical density during the afterglow phase took always less than 100 ms. Furthermore, a short overshoot was measured in CF density traces, directly after the plasma pulse start. The temporal resolution of about 30 ms, achieved in the standard approach of the applied InfraRed Tunable Diode Laser Absorption Spectroscopy (IR-TDLAS), was not enough for a detailed analysis of the CF–kinetics. Therefore, another data acquisition approach was established in the present work, which improved the temporal resolution to 940 µs. The high time-resolved CF density measurements enabled a proper analysis of the radical kinetics at the beginning of both "plasma on" and "plasma off" phase. In particular, CF production due to the electron impact fragmentation of C2F4 molecules at the beginning of the plasma pulse appeared to be the dominant reaction channel for the overshoot formation.
[1] O. Gabriel, S. Stepanov and J. Meichsner J. Phys. D: Appl. Phys. 40 (2007) 7383