Plasma species prediction using direct simulation Monte Carlo (DSMC).

摘要

This paper explores the properties and behavior of gas-phase reactant and product specie involved in the plasma-enhanced chemical vapor deposition (PE-CVD) of diamond film, with the aims of improving the prediction, design, and processes related to the PE-CVD of diamond film. The goals are to (1) maximize the (H/CH3) ratio at the substrate surface, (2) maximize the methyl radical concentration (CH3) at the surface, and (3) maximize the ratio of electron projectile-to-gas particle target, all goals consistent with experimental and analytical research to date. The principal tool used in this exploration is the Direct Simulation Monte Carlo (DSMC) method. The principal case considered is that of an isentropically expanding low temperature, rarefied Argon-Hydrogen-Methane parent mixture flowing hypersonically through a high energy electron beam towards a deposition target substrate. Principal variables include parent stagnation temperature and pressure, partial pressures of the parent specie (i.e., relative concentrations), electron beam energy, and substrate surface properties. Only the gas phase plasma generation, transport, and substrate surface impact mechanics are addressed; surface chemistries are not.