Radiation-sensitive resin composition and method of forming resist pattern

A radiation-sensitive resin composition comprising:

• a polymer which comprises:
• a first structural unit represented by formula (5);
• and a second structural unit represented by formula (6);
• and
• a radiation-sensitive acid generating agent which comprises a compound represented by formula (2):
• wherein, in the formula (5), R10 represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group;
• Ar3 represents a group obtained by removing (t+u+1) hydrogen atoms on an aromatic ring from an arene having 6 to 20 ring atoms;
• t is an integer of 0 to 10, wherein in a case in which t is 1, R11 represents a halogen atom or a monovalent organic group having 1 to 20 carbon atoms, and in a case in which t is no less than 2, a plurality of R11s are identical or different and each R11 represents a halogen atom or a monovalent organic group having 1 to 20 carbon atoms, or at least two of the plurality of R11s taken together represent a ring structure having 4 to 20 ring atoms together with the carbon chain to which the at least two of the plurality of R11s bond;
• and u is an integer of 1 to 11, wherein a sum of t and u is no greater than 11,
• in the formula (6), R12 represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group;
• R13 represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms;
• and R14 represents a divalent alicyclic hydrocarbon group having 3 to 30 ring atoms, and
• in the formula (2), Ar1 represents a group obtained by removing (q+1) hydrogen atoms on an aromatic ring from an arene formed by condensation of at least two benzene rings;
• R4 represents a monovalent organic group having 1 to 20 carbon atoms;
• p is an integer of 1 to 3, wherein in a case in which p is 1, two R4s are identical or different from each other;
• q is an integer of 0 to 7, wherein in a case in which q is 1;
• R5 represents a halogen atom;
• a hydroxy group, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms, and in a case in which q is no less than 2, a plurality of R5s are identical or different and each R5 represents a halogen atom, a hydroxy group, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms, or at least two R5s taken together represent an alicyclic structure having 4 to 20 ring atoms or an aliphatic heterocyclic structure having 4 to 20 ring atoms, together with the carbon chain to which the at least two R5s bond;
• in a case in which p is no less than 2, a plurality of Ar1s are identical or different from each other, and a plurality of q's are identical or different from each other;
• and X− represents a monovalent anion.