Hannover 2016 – scientific programme

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P: Fachverband Plasmaphysik

P 27: Low Temperature Plasmas III

P 27.7: Talk

Friday, March 4, 2016, 12:30–12:45, b305

High power impulse sputtering of chromium: correlation between the energy distribution of chromium ions and spoke formation — •Wolfgang Breilmann, Alexandra Eitrich, Christian Maszl, Ante Hecimovic, Vincent Layes, Jan Benedikt, and Achim von Keudell — Ruhr-Universität Bochum, Experimentalphysik II

The ion energy distribution functions (IEDF) of high power impulse magnetron sputtering (HiPIMS) plasmas show ions with kinetic energies up to 100eV, which do not exist in conventional dc magnetron sputtering discharges. The origin of these high energetic ions is a local maximum of the electric potential inside of ionization zones (IZ). These IZ, also called spokes, are structures of high plasma density, which rotate along the racetrack in ExB direction. With increasing peak current density the amount of spokes reduces until, in the case of a chromium target, they form a homogeneous discharge again. The transition from the no spokes to spokes regime and from the spokes to homogeneous regime have been observed with an energy and time resolved ion mass spectrometer and electrical probe experiments. Mass spectrometry measurements then showed the evolution of the IEDF and its dependence on the spokes regime. It was observed that a high energetic group of ions is generated when spokes occur. Furtheremore, the homogeneous regime mostly affects the low energy part of the IEDF, as it increases the potential difference between the discharge and the mass spectrometer. Thus, the homogeneous discharge is considered to be a single IZ.