Hybrid Plasma Simulation of Capacitively-Coupled O2 Plasma at Moderate Pressure

Plasma modeling is performed for oxygen RF capacitively coupled discharges at moderate pressures of a few Torrs. In this model, all neutral and charged species are primarily treated as fluids. The secondary electrons are treated kinetically using a Monte Carlo model,. Our fluid model includes continuity equations for charged and neutral species, drift-diffusion approximation for electron flux, the momentum conservation equation for ions, and the Poisson equation for electric potential. The secondary electrons emitted from the surface are treated kinetically to model the acceleration these electrons experience when going through the sheath. This kinetic secondary electron model is coupled with the fluid bulk plasma model so that the ionization caused by these secondary electrons is captured in the physics of simulations. The electrode potential, electrode current, and the phase difference between potential and current are compared with the experiments conducted in the modified Gaseous Electronics Chamber (mGEC) chamber at the University of Texas Dallas. The modeling results along with diagnostics can provide understanding of plasma behavior at moderate pressure. The modeling results of complex chemistry in oxygen plasma is significant where electronegativity of the plasma due to O^- ions plays an important role. Variations in plasma characteristics with gas pressure and power is investigated.