Salt suitable for an acid generator and a chemically amplified resist composition containing the same

A process for producing a salt of the formula (I)

• wherein X represents —OH or —Y—OH, n is an integer of 1 to 9, A+ represents an organic counter ion, Y represents a divalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms,
• which comprises reacting an ester of the formula (VI)
• wherein X represents —OH or —YOH, n is an integer of 1-9, Y represents a divalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms, and M represents Li, Na, K or Ag, with an onium salt of the formula (VII)
• A+Z− (VII)
• wherein A+ represents an organic counter ion, and Z− represents F−, Cl−, Br−, I−, BF4−, AsF6−, SbF6−, PF6− or ClO4−.

A chemically amplified resist composition comprising

• a salt of the formula (I)
• wherein X represents —OH or —Y—OH, n is an integer of 1 to 9, A+ represents a counter ion, Y represents a divalent sated aliphatic hydrocarbon group having 1 to 6 carbon atoms;
• and
• a resin which contains a structural it having an acid-labile group and which itself is insoluble or poorly soluble in an alkali aqueous solution but becomes soluble in an alkali aqueous solution by the action of an acid.