Electron collision cross sections for the TMS molecule and electron transport coefficients in TMS-Ar and TMS-O₂ mixtures

A consistent set of low-energy electron-collision cross sections for the tetramethylsilane (TMS) molecule has been derived from the measured electron transport coefficients for a pure TMS molecule by using an electron swarm study and a two-term approximation of the Boltzmann equation for energy. The electron transport coefficients, which were calculated by using the derived set, are consistent with the experimental data over a wide range of E/N values (ratio of the electric field E to the neutral number density N). The present set of electron collision cross sections for the TMS molecule, therefore, is the best available so far for quantitative numerical modeling of plasma discharges for processing procedures with materials containing TMS molecules. The electron-transport coefficients in TMS-Ar and TMS-O₂ mixtures were also calculated and analyzed in a wide range of E/N ratios for the first time. The presence of a remarkable synergism in the Townsend first ionization coefficient has been pointed out in the TMS-O₂ mixtures.