Jena 2013 – scientific programme
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P: Fachverband Plasmaphysik
P 7: Niedertemperaturplasmen I
P 7.4: Talk
Tuesday, February 26, 2013, 17:30–17:45, HS 3
The effect of powder formation on the electron dynamics and discharge symmetry in single and dual frequency hydrogen/silane plasmas — •Edmund Schüngel, Sebastian Mohr, Shinya Iwashita, Julian Schulze, and Uwe Czarnetzki — Institute for Plasma and Atomic Physics, Ruhr-University Bochum
Highly diluted SiH4 plasmas are used in the silicon thin film industry as well as for fundamental investigations of dusty plasmas. Nevertheless, the basic mechanisms in these plasmas are not fully understood yet. In particular, the formation of powder can have a dramatic impact on the discharge properties. We investigate capacitively coupled hydrogen/silane discharges at pressures above 100 Pa and show, that the spatial distribution of the dust particles strongly affects the symmetry of the discharge. This can be understood based on the electron dynamics. Similar to electronegative discharges, the electron heating and, thus, the spatial ionization profile is mainly determined by the distribution of the heavy negatively charged species. Therefore, the ion density profile is changed. The mechanisms described above are investigated in single and electrically asymmetric dual frequency discharges and the consequences of the powder formation on the Electrical Asymmetry Effect, which allows the control of the discharge symmetry by tuning the symmetry of the applied voltage waveform, are examined.