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P: Fachverband Plasmaphysik

P 13: Poster: Niedertemperaturplasmsen

P 13.20: Poster

Dienstag, 13. März 2012, 16:30–19:00, Poster.III

Experimental study of capacitive discharges used for thin film deposition driven by asymmetric voltage waveforms — •Edmund Schüngel, Sebastian Mohr, Julian Schulze, and Uwe Czarnetzki — Intitute for Plasma and Atomic Physics, Ruhr-University Bochum

The application of a voltage waveform consisting of two consecutive harmonics is a promising method for controlling the symmetry of capacitively coupled radio frequency (CCRF) discharges. The key parameter is the phase angle between the two driving frequencies. By changing the phase angle, the sheath widths and voltages as well as the mean ion energies at the electrode surfaces can be varied, while the plasma density and ion flux are kept constant. After detailed fundamental investigations of the Electrical Asymmetry Effect (EAE) in argon [1], its effectiveness has also been proven in electronegative [2] plasmas. Here, we show an experimental study of the EAE in the regime of CCRF discharges typically used for silicon thin film deposition purposes, e.g. in solar cell manufacturing. First results in hydrogen and hydrogen-silane gas mixtures at total gas pressures of several hundred Pascal will be discussed.

Funding by the German Federal Ministry for the Environment (0325210B) is gratefully acknowledged. [1] U. Czarnetzki et al. Plasma Sources Sci. Technol. 20 (2011) 024010 [2] J. Schulze et al. Plasma Sources Sci. Technol. 20 (2011) 045008