Synthesis of N ‐Substituted Maleimides and Poly(styrene‐ co ‐ N ‐maleimide) Copolymers and Their Potential Application as Photoresists

Poly(styrene-co-N-maleimide) copolymers bearing tert-butoxycarbonyl (t-BOC)-protected amine groups attached to side chains of varying lengths are synthesized via activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP) and investigated from the perspective of photoresist applications. The length of the alkyl substituents enables control of thermal properties as well as hydrophobicity, which are critically important for resist processing. Removal of the acid labile t-BOC group during deep-UV (DUV)exposure shifts solubility in the exposed areas and well-defined line space patterns of 1 µm are obtained for the selected copolymers. The correlation between glass transition temperature (Tg) and solubility contrast determines the lithographic performance where the copolymers with shorter alkyl chains exhibit promising results.