Electron power absorption in capacitively coupled plasmas operated in gas mixtures containing oxygen

Capacitively Coupled Plasmas (CCPs) operated in gas mixtures containing oxygen are studied by Particle-in-Cell/Monte Carlo Collisions (PIC/MCC) simulations. The changes of the discharge characteristics are investigated by adding oxygen to noble gases. In the PIC/MCC simulations, a complex model is applied, which includes the cross processes between the various species of the gas components and accounts for the surface processes. This model has been verified by Phase Resolved Optical Emission Spectroscopy (PROES) measurements of neon-oxygen mixtures, providing a good agreement between the excitation rates of the neon 2p1 state. The electron power absorption dynamics in such mixtures is found to change significantly as the mixing ratio of the two gases and the pressure is varied. As the pressures or the oxygen concentration is increased, the Ohmic heating becomes the dominant mechanism of electron power absorption, while the contribution of electron power absorption from the ambipolar electric field becomes minor.