Kiel 2011 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 16: Poster: Niedertemperaturplasmen

P 16.2: Poster

Mittwoch, 30. März 2011, 16:30–18:30, Foyer

The Electrical Asymmetry Effect in oxygen discharges — •Edmund Schüngel¹, Quanzhi Zhuang², Shinya Iwashita¹, Julian Schulze^1,3, Jiang Wei², Lu-Jing Hou⁴, You-Nian Wang², and Uwe Czarnetzki¹ — ¹Institute for Plasma and Atomic Physics, Ruhr-University Bochum — ²School of Physics and Optoelectronic Technology, Dalian University of Technology, China — ³Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences — ⁴Max Planck Institute for Extraterrestrial Physics, Garching

Capacitively coupled radio frequency discharges are of paramount importance in etching and deposition processes. In these applications, gases revealing a complex chemistry, e.g. including several ion species’, are often used. Here, separate control of ion energy and ion flux at the processing surfaces is the key to optimizations. This can be achieved via the Electrical Asymmetry Effect (EAE). The symmetry of the discharge and, therefore, the ion energies at the electrodes are controlled via the phase angle between the fundamental frequency and its second harmonic, which are applied to the discharge. However, all investigations of the EAE have been restricted to argon discharges up to now. Here, an electrically asymmetric electronegative discharge is set up experimentally and in a PIC/MCC simulation. The results include the dc self bias, the discharge current and the spatial density profiles of positive and negative ions and electrons. They show that the effect works well in oxygen, although some deviations compared to electropositive (argon) plasmas are found, especially in the high pressure regime at about 100 Pa. An analytical model is used to explain the results.