Abstract
In order to study photoinitiating mechanism of photochemically initiated radical polymerization in thick negative photoresist, fluorescence lifetime analyses of dry film photoresist were conducted by gallium nitride semiconducter laser pumped single-photon counting method. Lifetimes of photosensitizers, 4-methyl-7-(N,N-diethyl)aminocoumarin (C1), 4,4'-(N,N,N',N'-tetraethy)aminobenzophenon (EAB), 1-phenyl -3-[2-(4''-t-butylphenyl)vinyl]-5-(4'''-t-butyl) phenylpyrazoline (Pyraz) or 9,10-di-n-butoxyanthracene in film resists with and without photoinitiator, 2,2'-bis (σ-methylphenyl)-4,4',5,5'-tetraphenyl- imidazole (Me-HABI), as a quencher were successfully obtained. Quenching efficiencies, η, defined as 1-(τ/τ0), were compared with photoinitiaing efficiencies which were obtained by RT-FTIR measurement of double bond disappearance and photospeed determined by gray scale step method. From correlation between quenching efficiencies and photoinitiating efficiencies in an extent, it was elucidated that the singlet excited state of photosensitizer seems to involve in the photoinitiation process as an important process.
