Pulse Radiolysis Study on a Highly Sensitive Chlorinated Resist ZEP520A

ZEP520A is one of the most popular positive electron beam (EB) resists used in research and photomask fabrication owing to its good spatial resolution, high sensitivity, and high dry etching resistance. Herein, EB-induced early reactions of ZEP520A were investigated via pulse radiolysis. Dissociative electron attachment and formation of a charge transfer complex were definitive contributing factors to the efficient degradation of ZEP520A. Furthermore, products induced by direct ionization of ZEP520A were observed in a highly concentrated ZEP520A solution in tetrahydrofuran, suggesting that early reactions in the ZEP520A solid film that were induced only by direct ionization could be simulated during pulse radiolysis in specific solutions.