Silicon Etching in $XeF_2$ Environment

Enhancement of silicon etching rate in $XeF_2$ environment is considered by a proposed model, which includes processes of adsorption, activation, chemical reactions, relaxation, desorption, and sputtering. The enhancement of silicon etching rate is explained by considering hydrocarbon molecules from background gas contamination in the vacuum chamber, and assuming that hydrocarbon radicals enhance the etching rate. The composition of the adsorbed layer during silicon etching in $XeF_2$ environment is calculated. It is found that hydrocarbon radicals intensify reaction of $XeF_2$ molecules with Si atoms on the surface and that this changes the kinetics of the etching rate. Using the obtained theoretical results the difference in kinetics of the etching rates of first and subsequent run is explained.