A resist composition comprising a sulfonium salt of a carboxylic acid having a nitro-substituted benzene ring is provided. The carboxylic acid is free of iodine and bromine, and when the benzene ring is fluorinated, the number of fluorine atoms is up to 3. The resist composition offers a high sensitivity, reduced LWR and improved CDU independent of whether it is of positive or negative tone.

A resist composition comprising a sulfonium salt of a carboxylic acid having a nitro-substituted benzene ring is provided. The carboxylic acid is free of iodine and bromine, and when the benzene ring is fluorinated, the number of fluorine atoms is up to 3. The resist composition offers a high sensitivity, reduced LWR and improved CDU independent of whether it is of positive or negative tone.

Disclosed are a salt represented by formula (I), an acid generator, and a resist composition comprising the same: ##STR00001##
wherein R.sup.1 and R.sup.2 each represent a hydroxy group, *OR.sup.10, *O-L.sup.10-COOR.sup.10; L.sup.10 represents an alkanediyl group; R.sup.10 represents an acid-labile group; R.sup.4, R.sup.5, R.sup.7 and R.sup.8 each represent a halogen atom, a haloalkyl group or a hydrocarbon group; A.sup.1 and A.sup.2 each represent a hydrocarbon group, the hydrocarbon group may have a substituent, and CH.sub.2 included in the hydrocarbon group may be replaced by O, CO, S or SO.sub.2; m1 represents an integer of 1 to 5, m2 and m8 represent an integer of 0 to 5, m4, m5 and m7 represent an integer of 0 to 4, 1m1+m75, 0m2+m85; and Al.sup. represents an organic anion.