A Monte Carlo sensitivity analysis of CF2 and CF radical densities in a C - C ~ F ~ plasma

A Monte Carlo sensitivity analysis is used to build a plasma chemistry model for octacyclofluorobutane (cc4F8) which is commonly used in dielectric etch. Experimental data are used both quantitatively and quahtatively to analyze the gas phase and gas surface reactions for neutral radlcal chemistry. The sensitivity data of the resulting model identifies a few critical gas phase and surface aided reactions that account for most of the uncertainty in the CF2 and CF radlcal densities. Electron impact dissociation of small radicals (CF2 and CF) and their surface recombination reactions are found to be the rate-limiting steps in the neutral radical chemistry. The relative rates for these electron impact dissociation and surface recombination reactions are also suggested. The resulting m e c h s m is able to explain the measurements of CF2 and CF densities available in the literature and also their hollow spatial density profiles.