| AVS 62nd International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThA |
| Session: | Plasma Sources |
| Presenter: | Birk Berger, West Virginia University |
| Authors: | B. Berger, West Virginia University J. Franek, West Virginia University St. Brandt, West Virginia University M. Liese, Barthel HF-Technik GmbH, Germany M. Barthel, Barthel HF-Technik GmbH, Germany E. Schuengel, West Virginia University M. Koepke, West Virginia University J. Schulze, West Virginia University |
| Correspondent: | Click to Email |
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 an 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 realized 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 in Argon with an admixture of Neon as tracer gas for Phase Resolved Optical Emission Spectroscopy (PROES). Measurements were performed for gap lengths of 30mm and 40mm, different pressures (p=3, 5, 200Pa) and varying applied voltages (V=120, 210V). 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 using more than two consecutive harmonics significantly enlarges the control range of the mean ion energy. Additionally, the effect of tuning the phases on the electron heating and sheath dynamics within one low frequency cycle is investigated using PROES and correlated with changes of ion energy distributions at the electrodes.