Jena 2013 – scientific programme

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P: Fachverband Plasmaphysik

P 7: Niedertemperaturplasmen I

P 7.2: Talk

Tuesday, February 26, 2013, 17:00–17:15, HS 3

Electron heating mechanisms in electrically asymmetric capacitive hydrogen/silane discharges - A parameter study — •Sebastian Mohr, Edmund Schüngel, Julian Schulze, and Uwe Czarnetzki — Ruhr - Universität Bochum

We investigate capacitively coupled electrically asymmetric dual frequency hydrogen - diluted silane discharges. In electrically asymmetric discharges, a fundamental frequency and its second harmonic are used to generate a DC self bias on the blocking capacitor. The value of this DC self bias depends on the phase angle between the two frequencies. This is used to control the ion energy at surfaces independently from the ion fluxes. Depending on gas pressure and the silane concentration, different electron heating mechanisms occur in these discharges. This is related to the variable densities of negative ions and dust particles. At low concentrations of these particles, the electron heating is dominated by the sheath motion via the sheath expansion and field reversals. Higher concentrations reduce the electron density in the bulk and induce a high electric field and electron heating inside the bulk. We will present a parameter study of electrically asymmetric hydrogen - diluted silane discharges combining experiments with computer simulations and discuss the impact of the different heating mechanisms on the DC self bias.