2013 Volume 26 Issue 5 Pages 635-641
The chemical reaction in EUV irradiation of the several photoacid generators (PAGs) which employed triphenylsulfonium (TPS) salts as the cation of PAG, is discussed on the basis of the analysis using the SR absorption spectroscopy in the soft x-ray region. The fluorine atoms of the anion PAGs which have the chemical structure of the imidate type such as TPS-Imidate-1, and TPS-Imidate-2 strongly decomposed under EUV exposure. In the case of these PAG type, it is found that in addition to the ionization reaction, the anion decomposition reaction originated by the photo excitation of the photoacid generator might occur under EUV exposures. Thus the sensitivity seemed to be high comparison to tri-phenylsulfonium perfluorobutanesulfonate (TPS-Nonaflate) under EUV exposure. In the case of tri-phenylsulfonium camphorsulfonate (TPS-Cs), the anion which does not contain fluorine seemed to be very stable under EUV exposure and the sensitivity is lower than TPS-Nonaflate.
