Sulfonium salt, resist composition, and patterning process

摘要

A sulfonium salt of a naphthylsulfonium cation having a hydrophilic phenolic hydroxyl group or ethylene glycol chain with a specific anion is provided. The sulfonium salt is used as a photoacid generator to form a resist composition which when processed by immersion lithography, offers advantages of restrained dissolution in the immersion water and less pattern dependence or dark-bright difference.