Fluid models for RF-CCPs at intermediate pressure: estimating transport coefficients

RF-CCPs at gas pressures above ~1 Torr are often simulated by fluid models using the drift-diffusion approximation, since Particle-in-Cell (PIC) models are too computationally intensive. Fluid models require the electron transport coefficients, as well as rate constants. These are calculated from the electron energy distribution function (EEDF), which is commonly estimated using either the local field approximation or by assuming Maxwellian or Druyvesteyn distributions. Furthermore, under these pressure conditions, the ion inertial terms, that are neglected in the drift-diffusion model, can play an important role in the transport of ions. We compare these fluid approaches to a full PIC model in different CCP argon discharges in the intermediate pressure range.