Effect of tert-butyl substituents in triphenylsulfonium cation on spectral properties and photochemical activity of photoacid generators

Four photoacid generators such as triphenylsulfonium triflate and nonaflate, 4-tert-butylphenyl(diphenyl)sulfonium nonaflate and tris(4-tert-butylphenyl)sulfonium nonaflate were synthesized, and their spectral characteristics were investigated in the polymer matrix. The dependence of the photosensitivity of resist films on the efficiency of absorption of actinic radiation and the quantum yields of acid generation was found. Triphenylsulfonium triflate salt and tris(4-tert-butylphenyl) sulfonium nonaflate were shown to be promising photoacid generators with a resist sensitive to irradiation by ArF and KrF excimer lasers, respectively.