Outgassing Analysis in EUV Resist

We found that tri-phenysulfonium cyclo(1,3-perfluoropropanedisulfone) imidate (TPS-Imidate) as a photo acid generator (PAG) is more sensitive rather than tri-phenysulfonium perfluorobutanesulfonate (TPS-PFBS) by EUV exposure. In this paper, we discussed the outgassing characteristics of our discovered the new PAG resist system to better understand the detailed mechanism for obtaining a high sensitivity. As for resist B which employs TPS-PFBS as the PAG was measured larger amount of isobutene (m/z 56) and benzene (m/z 78) than that of resist A. As for resist C which employs TPS-Imidate as a PAG, the amount of benzene was larger than that of resist B. It suggests that resist C shows faster sensitivity due to the high amount of acid generated by EUV exposure. In addition, resist C contains PAG anion of imidate derivatives, which carried out distinctive photolysis reactions under EUV exposure. This reaction will be expected to generate many acidic species, which has the potential of becoming a catalyst for the de-protecting reaction. This mechanism is very useful for the resist design to obtain a high sensitivity EUV resist.