Evaluation of desorption activation energy of SiF2 molecules

The chemical etching of silicon in F2 ambient is considered. The desorption activation energy for an SiF2 molecule is evaluated using an experimentally measured dependence of etching rate on concentration of F2 molecules. It is found that the desorption activation energy of SiF2 molecules is equal to Ed = (0.815 ± 0.010) eV. This corresponds to a value of the mean lifetime of adsorbed molecules on the surface of τ = (26 ± 3) ms at temperature T = 376 K.