Differential and partial ionization cross sections for electron impact ionization of plasma processing molecules: CF4 and PF5

Abstract

The semiempirical approach that requires the oscillator strength data as input has been employed to evaluate the single and double differential cross sections corresponding to the production of various cations, CFx+ (x=0–3), F+, CF2++ and CF3++ from CF4 and PFx+ (x=0–4), F+ and PFx++ (x=0–4) from the PF5 molecule, through dissociative electron ionization processes. The calculations are made as a function of secondary electron energy and angle at fixed incident electron energies of 100 and 200 eV. The corresponding partial and total ionization cross sections have also been derived in the energy range varying from ionization thresholds to 1000 eV. Comparison of the evaluated partial and total ionization cross sections is made with the experimental and theoretical data wherever available. The formula has been extended to the calculation of ionization rate coefficients as a function of electron temperature/energy using the Boltzmann energy distribution function.