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 ring X represents monocyclic or bicyclic hydrocarbon group having 3 to 30 carbon atoms, and one or more hydrogen atom in the ring X is optionally substituted with alkyl group having 1 to 6 carbon atom alkenyl group having 2 to 6 carbon atoms, alkoxy group having 2 to 6 carbon atoms or perfluoroalkyl group having 1 to 4 carbon atoms;
• Q1 and Q2 each independently represent fluorine atom or perfluoroalkyl group having 1 to 6 carbon atoms;
• A+ rep resets organic counter ion;
• and n is an integer of 1 to 12,
• which comprises reacting an ester compound of the formula (VI)
• wherein M represent Li, Na, K or Ag;
• and n is an integer of 1 to 12, and wherein ring X represents monocyclic or bicyclic hydrocarbon group having 3 to 30 carbon atoms and one or more hydrogen atoms on the ring X are optionally replaced with alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 2 to 6 carbon atoms or a perfluoroalkyl group having 1 to 4 carbon atoms;
• and Q1 and Q2 each independently represents a fluorine atom or perfluoroalkyl group having 1 to 6 carbon atoms with a compound of the formula (IX)
• A+ Z− (IX)
• wherein Z represents F, Cl, Br, I, BF4, AsF6, PF6 or ClO4, and A+ represents an organic counter ion.

A chemically amplified resist composition comprising a salt of the formula (I)

• wherein ring X represents monocyclic or bicyclic hydrocarbon group having 3 to 30 carbon atoms, and one or more hydrogen atom in the ring X is optionally substituted with alkyl group having 1 to 6 carbon atoms, alkenyl group having 2 to 6 carbon atoms, alkoxy group having 2 to 6 carbon atoms or perfluoroalkyl group having 1 to 4 carbon atoms;
• Q1 and Q2 each independently represent fluorine atom or perfluoroalkyl group having 1 to 6 carbon atoms;
• A+ represents organic counter ion;
• and n is an integer of 1 to 19, and a resin which contains a structural unit 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.