MODELING OF DISCHARGES AND NONTHERMAL PLASMAS - APPLICATIONS TO PLASMA PROCESSING

We present an overview of models of low pressure, non-thermal gas disc harges as commonly used in plasma processing. Significant progress has been made in the past decade towards the goal of a self-consistent mo del of the electrical properties of discharges, whether d.c., r.f. or microwave discharges. These models are based on solutions of the charg ed particle transport equations coupled with Poisson's equation for th e electric field, and provide the space and time distribution of charg ed particle densities, current densities and electric field or potenti al. Some of the most sophisticated models also provide the electron an d ion velocity distribution functions in the discharge at any point in space or time. It is now possible to describe reasonably accurately t he physical properties of a discharge (including the plasma, the elect rode regions and the walls) for two-dimensional cylindrical geometries , even for complex electrode configurations involving e.g. a hollow ca thode or anode. A survey of the available models is presented here and we illustrate the current state of the art by results from one- and t wo-dimensional models of d.c., r.f. and transient discharges.