Mathematical modeling and interpretation of reactive plasma chemistry

A problem of much recent technological interest is the analysis and interpretation of the chemistry of audiofrequency plasma enhanced chemical vapor deposition of thin films. In this process, low pressure methane gas is input into a reactor chamber and a low-current, high-voltage audiofrequency electric discharge applied. The energetic electrons thus produced bombard the methane molecules, fragmenting them, and causing radical and ion formation. These new species go on to form a range of products under various operating conditions from soot-like amorphous carbon, to diamond-like carbon. Despite the increasing experimental understanding of reactive organic plasma dynamics, the chemical kinetics of the reactions in the gas phase is still not completely understood: quite different species densities are found in different regions of the discharge system implying spatially inhomogeneous physiochemical processes. The experimental problem is first outlined, and a simple physiochemically-motivated reaction-advection-diffusion model of the reactive plasma chemistry described. Results of the kinetics models are presented and discussed in terms of the input model parameters and related to surface deposition.