| abstract |
The invention provides a novel sulfonium salt having at least one acid labile group attached to a phenyl group in a molecule and a normal, branched or cyclic C1-C20 alkylsulfonate anion. The novel sulfonium salt is effective for increasing the dissolution contrast between exposed and unexposed areas. Upon exposure, it generates an alkylsulfonic acid which is a weak acid, minimizing the influence of side reaction and deactivation during PEB step. The sulfonium salt is useful in a chemically amplified positive resist composition which lends itself to fine patterning and features high resolution. |