Homogeneous and Heterogeneous Chemistry of Methane Deposition Plasmas

Abstract

AbstractExperimental measurements and theoretical modeling of methane deposition plasmas have made it possible to determine the most likely homogeneous and heterogeneous chemical reaction paths leading to deposition of hydrogenated carbon from the fragments of electron dissociated methane.The methane plasma was modeled as a plug-flow reactor.Gas phase reactions, diffusive transport, variable surface reflection coefficients, and surface chemical reactions are included in the model which follows a “plug” of gas as it flows through the reactor.Boltzmann equation and Monte Carlo calculations were used to determine the electron energy distribution and the resulting dissociation and ionization rate coefficients averaged over space and time.Experimental measurements of the time dependent electrical properties of the plasma are used as input to the model.Deposition rates, deposition uniformity, downstream mass spectroscopy, and the dependences of these quantities on power and mass flow rates are compared to the model to arrive at a consistent representation of the deposition chemistry.