title: Power supply and impedance matching to drive technological radio-frequency plasmas with customized voltage waveforms.
abstract: We present a novel radio-frequency (RF) power supply and impedance matching to drive technological plasmas with customized voltage waveforms. It is based on a system of phase-locked RF generators that output single frequency voltage waveforms corresponding to multiple consecutive harmonics of a fundamental frequency. These signals are matched individually and combined to drive a RF plasma. Electrical filters are used to prevent parasitic interactions between the matching branches. By adjusting the harmonics' phases and voltage amplitudes individually, any voltage waveform can be approximated as a customized finite Fourier series. This RF supply system is easily adaptable to any technological plasma for industrial applications and allows the commercial utilization of process optimization based on voltage waveform tailoring for the first time. Here, this system is tested on a capacitive discharge based on three consecutive harmonics of 13.56 MHz. According to the Electrical Asymmetry Effect, tuning the phases between the applied harmonics results in an electrical control of the DC self-bias and the mean ion energy at almost constant ion flux. A comparison with the reference case of an electrically asymmetric dual-frequency discharge reveals that the control range of the mean ion energy can be significantly enlarged by using more than two consecutive harmonics.
authors.affiliation: Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA.
authors.forename: James
authors.initials: J
authors.lastname: Franek
authors.affiliation: Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Brandt
authors.affiliation: Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA.
authors.forename: Birk
authors.initials: B
authors.lastname: Berger
authors.affiliation: Barthel HF-Technik GmbH, Walkmühlenstrasse 16, 52074 Aachen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Liese
authors.affiliation: Barthel HF-Technik GmbH, Walkmühlenstrasse 16, 52074 Aachen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Barthel
authors.affiliation: Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA.
authors.forename: Edmund
authors.initials: E
authors.lastname: Schüngel
authors.affiliation: Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, USA.
authors.forename: Julian
authors.initials: J
authors.lastname: Schulze