Simulations of ion transport in a collisional radio-frequency plasma sheath

A hybrid theoretical model, capable of describing the characteristics of a collisional sheath driven by a sinusoidal current source and determining the energy and angular distributions of ions incident onto the substrate, is proposed. The model consists of one-dimensional time-dependent fluid equations coupled with the Poisson equation determining spatiotemporal evolution of the sheath and the Monte Carlo simulation predicting the energy and angular distributions of ions striking the electrode, in which charge-exchange collisions between ions and neutrals are included. Additionally, an equivalent circuit model in conjunction with the fluid equations is adopted to self-consistently determine the relationship between the instantaneous potential at a rf-biased electrode and the sheath thickness. It is found that the collisional effects would influence the height of the energy peaks in the ion energy distributions and the ion angular distributions.