Influence of the bias signal amplitude and frequency on the harmonic probe measurements in plasma diagnostics

Abstract

The harmonic probe technique may be used for the diagnostics of the plasma in insulative film deposition circumstances where the conventional Langmuir probe cannot work. In this study, we investigated the influence of the bias signal amplitude V0 and frequency f of the harmonic probe on the diagnostic results. While the measured electron temperature Te and ion density ni change little with f within the frequency range of 1–10 kHz, both of them show a considerable increase with V0. The reasons for the results were analyzed, and based on the understanding, an improved harmonic probe technique was proposed. The validity of the improved technique was verified by comparing its results with those of a conventional Langmuir probe in Ar plasmas. The improved harmonic probe technique was applied in diagnostics of the plasma circumstance for microwave electron cyclotron resonance plasma enhanced radio frequency magnetron sputtering deposition of SiNx films.