Abstract
A new class of photoresists consisting of vinyl aromatic polymers bearing electron releasing substituents or halogens together with photosensitive onium salts such as diaryliodonium and triarylsulfonium salts have been developed. On irradiation with UV light at wavelengths absorbed by the onium salts, these photoresists undergo facile cross‐linking. Therefore, they provide negative tone photoresists with a high degree of photosensitivity. Mechanisms which rationalize the cross‐linking reactions are proposed.