Development of Fast-Photospeed Chemically Amplified Resist in Extreme Ultraviolet Lithography

In a high-annealing type resist system that employs polyhyodroxy styrene as a base resin, we found that tri-phenysulfonium cyclo(1,3-perfluoropropanedisulfone) imidate when employed as a photoacid generator (PAG) is more sensitive than tri-phenysulfonium nonaflate under extreme ultraviolet (EUV) exposure. However, their sensitivities are almost the same under KrF and EB exposures. As results of both outgassing species and FT-IR measurements, the EUV-induced reaction of cyclo(1,3-perfluoropropanedisulfone) imidate employed as an anion of PAG occurred more efficiently than that of nonaflate employed as an anion of PAG. Therefore, the anion of PAG contributes to achieve a fast photospeed under EUV exposure. Furthermore, from the sensitivity curve measurements, it is found that tri-phenylsulfonium employed as a cation increases the developing rate more than diphenyl-naphthylsulfonium employed as a cation of PAG. As a result, we have succeeded in developing a fast photospeed chemically amplified resist that has a sensitivity of 1.1 mJ/cm 2 and a partial pressure displacement accumulated in the total exposure time between after and before exposures on the order of 10 -6 Pa s.