Salt and photoresist composition containing the same

A salt represented by the formula (I-AA):

• wherein Q1 and Q2 each independently represent a fluorine atom or a C1-C4 perfluoroalkyl group,
• X1 represents a single bond or —(CH2)k—, and one or more —CH2— in —(CH2)k— can be replaced by —O— or —CO— and one or more hydrogen atoms in —(CH2)k— can be replaced by a C1-C4 aliphatic hydrocarbon group, and k represents an integer of 1 to 17,
• Y1 represents a C1-C36 aliphatic hydrocarbon group, a C3-C36 alicyclic hydrocarbon group or a C6-C36 aromatic hydrocarbon group, and the aliphatic hydrocarbon group, the alicyclic hydrocarbon group and the aromatic hydrocarbon group can have one or more substituents having no fluorine atom, and one or more —CH2— in the aliphatic hydrocarbon group and the alicyclic hydrocarbon group can be replaced by —O— or —CO—,
• A1 and A2 independently each represents a C1-C20 aliphatic hydrocarbon group, a C3-C20 alicyclic hydrocarbon group or a C6-C20 aromatic hydrocarbon group, or A1 and A2 are bonded each other to form a C3-C20 ring, and one or more hydrogen atoms in the aliphatic hydrocarbon group, the alicyclic hydrocarbon group, the aromatic hydrocarbon group and the ring can be replaced by a hydroxyl group, a C1-C12 alkyl group, a C1-C12 alkoxy group or a C3-C36 alicyclic hydrocarbon group,
• Ar1 represents a (m4+1)-valent C6-C20 aromatic hydrocarbon group which can have one or more substituents,
• B1 represents a single bond or C1-C6 alkylene group, and one or more —CH2— in the alkylene group can be replaced by —O— or —CO—,
• B2 represents a C4-C18 lactone ring group not capable of being eliminated by the action of an acid and one or more hydrogen atoms in the lactone ring group can be replaced by a cyano group, a C1-C20 aliphatic hydrocarbon group or a C3-C20 alicyclic hydrocarbon group, m1 and m2 independently each represents an integer of 0 to 2, m3 represents an integer of 1 to 3, with the proviso that m1 plus m2 plus m3 equals 3, and m4 represents an integer of 1 to 3.