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

A salt of the formula (IV):

• wherein X represents alkylene group or substituted alkylene group in which a —CH2— except for the one connected to the adjacent —COO— is substituted with —S— or —O—;
• Y represents hydrocarbon ring group containing at least one aromatic ring and having 5 to 30 carbon atoms in which one or more of —CH2— on the hydrocarbon ring is optionally substituted with —O— or —CO— and in which one or more of hydrogen atom on the hydrocarbon ring is optionally substituted with alkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, perfluoroalkyl group having 1 to 4 carbon atoms, hydroxyalkyl group having 1 to 6 carbon atoms, hydroxyl group or cyano group;
• Q1 and Q2 each independently represent fluorine atom or perfluoroalkyl group having 1 to 6 carbon atoms;
• M represents Li, Na, K or Ag;
• and n shows 0 or 1.

A process for producing a salt of the formula (IV):

• wherein X represents alkylene group or substituted alkylene group in which a —CH2— except for the one connected to the adjacent —COO— is substituted with —S— or —O—;
• Y represents hydrocarbon ring group containing at least one aromatic ring and having 5 to 30 carbon atoms in which one or more of —CH2— on the hydrocarbon ring is optionally substituted with —O— or —CO— and in which one or more of hydrogen atom on the hydrocarbon ring is optionally substituted with alkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, perfluoroalkyl group having 1 to 4 carbon atoms, hydroxyalkyl group having 1 to 6 carbon atoms, hydroxyl group or cyano group;
• Q1 and Q2 each independently represent fluorine atom or perfluoroalkyl group having 1 to 6 carbon atoms;
• M represents Li, Na, K or Ag;
• and n shows 0 or 1,
• which comprises esterifying an alcohol of the formula (V):
• HO—(X)n—Y (V)
• wherein X, Y and n have the same meanings as defined above,
• with a carboxylic acid of the formula (VI):
• wherein M and Q have the same meanings as defined above.

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

• wherein X represents alkylene group or substituted alkylene group in which a —CH2— except for the one connected to the adjacent —COO— is substituted with —S— or —O—;
• Y represents hydrocarbon ring group containing at least one aromatic ring and having 5 to 30 carbon atoms in which one or more of —CH2— on the hydrocarbon ring is optionally substituted with —O— or —CO— and in which one or more of hydrogen atom on the hydrocarbon ring is optionally substituted with alkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, perfluoroalkyl group having 1 to 4 carbon atoms, hydroxyalkyl group having 1 to 6 carbon atoms, hydroxyl group or cyano group;
• Q1 and Q2 each independently represent fluorine atom or perfluoroalkyl group having 1 to 6 carbon atoms;
• A+ represents organic counter ion;
• and n shows 0 or 1,
• which comprises reacting a salt of the formula (IV):
• wherein M represents Li, Na, K or Ag, and X, Y, Q1, Q2 and n have the same meanings as defined above,
• with a compound of the formula (VII):
• A+Z− (VII)
• wherein Z represents F, Cl, Br, I, BF4, AsF6, SbF6, PF6 or ClO4, and A+ has the same meaning as defined above.

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

• wherein X represents alkylene group or substituted alkylene group in which a —CH2— except for the one connected to the adjacent —COO— is substituted with —S— or —O—;
• Y represents hydrocarbon ring group containing at least one aromatic ring and having 5 to 30 carbon atoms in which one or more of —CH2— on the hydrocarbon ring is optionally substituted with —O— or —CO— and in which one or more of hydrogen atom on the hydrocarbon ring is optionally substituted with alkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, perfluoroalkyl group having 1 to 4 carbon atoms, hydroxyalkyl group having 1 to 6 carbon atoms, hydroxyl group or cyano group;
• Q1 and Q2 each independently represent fluorine atom or perfluoroalkyl group having 1 to 6 carbon atoms;
• A+ represents organic counter ion;
• and n shows 0 or 1, 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.