Mathematical modeling and interpretation of reactive plasma chemistry

A problem of much recent technological interest is the analysis and interpr etation of the chemistry of audiofrequency plasma enhanced chemical vapor d eposition of thin films. In this process, low pressure methane gas is input into a reactor chamber and a low-current, high-voltage audiofrequency elec tric discharge applied. The energetic electrons thus produced bombard the m ethane 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 diamondlike carbon. Despite the increasing experimental understanding of reactive organic plasma dynam ics, the chemical kinetics of the reactions in the gas phase is still not c ompletely understood: quite different species densities are found in differ ent regions of the discharge system implying spatially-inhomogeneous physio chemical processes. The experimental problem is first outlined, and a simpl e physiochemically-motivated reaction-advection-diffusion model of the reac tive plasma chemistry de scribed. Results of the kinetics models are presen ted and discussed in terms of the input model parameters and related to sur face deposition. (C) 1999 Elsevier Science Ltd. All rights reserved.