ArF photoresist polymers with nitrogen or sulfone moieties for negative tone development process

A series of nitrogen- and sulfone-containing polymers with different molecular weights and monomer compositions were prepared via free radical polymerization to investigate the effect of polymer structure on the ArF lithographic performance in negative tone development (NTD) process. Conventional ArF photoresist polymers (Ref) were also prepared for comparison purposes. It was found that there are optimum molecular weights of the photoresist polymers to give good lithographic performance in NTD process. Photoresists with amine-containing polymers showed contact hole (CH) patterns with some defects, which could be due to the large amount of acid-quenchable amine moieties in the polymers. Lithographic performance of photoresists with sulfonate-containing polymers was close to that with Ref polymers and much better than that with sulfonamide-containing polymers.