Simulation of two-dimensional radiofrequency methane plasma: comparison with experiments

Abstract

Summary form only given, as follows. A self-consistent two-dimensional radio-frequency glow discharge model has been developed in cylindrical coordinates using a fluid model. The objective of the study is to provide insights to charged species dynamics and investigate their effects on deposition process for a polyatomic depositing gas discharge. Swarm data as a function of electron energy for methane are provided as input to the model. A power-law scheme is used for the discretization of convection-diffusion terms in the model. The necessary dc bias for the discharge in the asymmetric reactor geometry is predicted by a trial-and-error method such that the cycle-averaged current to the powered electrode becomes zero. The simulations are performed for different experimental design and operating conditions. The model predictions of electron density profile and self-generated dc bias compared well with the experimental results. Comparisons were first made with the data obtained by Sugai and coworkers from Nagoya University, Japan. Computations were carried out for the same geometry and operating conditions of the experimental reactor to obtain the radial and axial variations of plasma variables. The contours of cycle averaged electron and positive ion densities are shown. The present model was used to simulate a second experimental reactor (with a different geometric configuration) at Chemical Vapor Deposition Laboratory, Drexel University. The model predictions of electron density, dc bias and power compared well with the experimental measurements. The validated model was then used to predict the temporal and spatial variations of plasma variables for different reactor operating conditions. The radial variations of species fluxes to the cathode are also presented at different operating conditions of the reactor as they are important for thin carbon film deposition process.