Plasma characterization for the reactive HiPIMS process regulation of vanadium oxides

Abstract

To regulate reactive high power impulse magnetron sputtering (R-HiPIMS) processes of vanadium oxides, plasma diagnostics based on the RF Sobolewski probe theory have been conducted in this study. In addition to the typical approach of using a probe inserted into the chamber at the substrate side, a novel non-invasive approach using the target as an in situ probe has also been developed. The RF Sobolewski probe method enables the measurements of ion flux, plasma density, electron temperature, as well as the sheath impedance during the HiPIMS process. The plasma characterization reveals that the imaginary part of sheath impedance is the most promising parameter for future R-HiPIMS process regulation. Furthermore, based on the HiPIMS discharge waveforms, it is found that the average cathode current per pulse proves to be more suitable than the peak current (density) for process regulation when constant HiPIMS average power is maintained.