STRUCTURAL CONTROL AND THE OPTIMIZATION OF CHLORINATED STYRENE-BASED ELECTRON RESISTS

A large number of chlorinated styrene-based resists has been prepared, both by the copolymerization of methylstyrene with chloromethylstyrene, and by the direct chlorination of methylstyrene polymers. These resists have been characterized, and Inokuti's equation has been applied to the lithographic data to obtain radiation chemical yields which have been related to polymer structure and composition. Inokuti's theory has also been used to predict the dependence of lithographic performance on polymer parameters. Qualitative and quantitative agreement between these predictions and experimental observations has been demonstrated in several polymer systems, and this theory has been shown to provide useful pointers to resist optimization. A number of comparatively high sensitivity polymers have been found which do not undergo chain scission on irradiation and which accordingly exhibit high contrasts. From this range of polymers several well-suited for use as electron resists have been selected.