Effect of Electron Energy Distribution Functions on Plasma Behavior in Moderate-Pressure RF Capacitively Coupled Plasmas

Electron energy distribution function (EEDF) is an important property of radio frequency plasmas. In fluid models of plasmas, the plasma behavior is dependent on the assumption about the EEDF. Fluid and hybrid modeling of moderate pressure RF capacitively coupled plasmas (CCP) are considered in this study. We use different EEDFs, such as Maxwellian, Druyvenstein, or that based on the solution of the Boltzmann equation. The electron impact reaction rates, collision frequency, and power consumed by the electrons are calculated, tabulated as a function of electron temperature, and utilized in the plasma model. Plasma modeling is performed for RF capacitively coupled plasma for Ar, O2, and their mixtures at different pressures and powers. The profile of electron density along with electron flux, source, and power deposition are compared as a function of the EEDF. The electrode voltage, current, and their phase are also compared with experimental data from a symmetric and an asymmetric plasma discharge. In order to get a deeper understanding, particle-in-cell Monte Carlo collision (PIC-MCC) modeling of the discharge is also performed. Insights from the PIC-MCC model and model – experiment comparison are used to make assessments about correct assumptions to use in fluid or hybrid models of moderate pressure CCPs.