Acid formation in polymer solids by radiation-induced chain reactions of diphenyliodonium salts

In order to develop chemically amplified radiation resist having ability of acid multiplication, acid formation in γ-irradiated polymer films and solutions of acetal compounds containing diphenyliodonium salt has been studied. Acids were generated in the films and solutions by chain reactions of large G-value. The G-value depends on the chemical structure of the polymers and acetal compounds. Compounds containing cyclic acetal structure give large G-values. This dependence can be explained by difference in the possibility of electron transfer from radicals of the polymers and acetal compounds to diphenyliodonium salt. Polyvinyl acetals will be a candidate for the dually amplified resist.