A model of resist ion beam etching (IBE) by noble gases ions is sugges
ted. It is based on data of the influence of ion and electron irradiat
ion on the properties of PMMA-based resists. PMMA resistance to IBE af
ter such an irradiation is under investigation. In accordance with the
proposed model in addition to physical sputtering, radiation induced
processes make a considerable contribution to IBE of polymer resists.