Difference in Reaction Schemes in Photolysis of Triphenylsulfonium Salts between 248 nm and Dry/Wet 193 nm Resists

Chemically amplified (CA) resists are important in the semiconductor industry because of their high orders of magnitude of sensitivity enhancement. The key components of CA resists are a polymer with an acid labile group and a photoacid generator (PAG) that produces an acid upon exposure to radiation. Although the photolysis of PAGs has been intensively studied, the difference in reaction schemes between 248 and 193 nm resists had not been clarified. In this work, we have focused on the reaction of Ph2S•+, which is one of the major intermediates in the photolysis of triphenylsulfonium triflate. It was revealed that the difference in reaction schemes between 248 and 193 nm resists is caused by the ion molecular reactions of a polymer radical cation produced by electron transfer from the polymer to Ph2S•+.

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