On the electrical asymmetry effect in large area multiple frequency capacitively coupled plasmas
Stefan Bienholz, Tim Styrnoll, Peter Awakowicz
JOURNAL OF PHYSICS D-APPLIED PHYSICS, Volume: 47, Issue: 6, Article Number: 065201, DOI: 10.1088/0022-3727/47/6/065201, Published: FEB 12 2014
Recently, many publications have dealt with the electrical asymmetry effect in capacitively coupled radio frequency-discharges. The idea of this concept is the possibility of controlling the self-bias voltage by tuning the relative phase of harmonics in relation to the fundamental wave. In this work, we apply the electrical asymmetry effect on a large-area multiple frequency capacitively coupled plasma used for reactive sputtering by varying the relative phase of the 13.56 and 27.12MHz excitation. The resulting voltage waveforms at the electrode are recorded using a high-voltage probe. The shape of the waveform is then analysed by Fourier analysis to study the influence of higher harmonics excited at the non-linearity of the plasma boundary sheath. To investigate the influence of the relative phase on the plasma itself, radially resolved multipole resonance probe measurements are performed.