Composition for forming liquid immersion upper layer film, and polymer

An immersion upper layer film-forming composition comprising:

• [A] a polymer component that comprises:
• a structural unit (I-1) represented by formula (1), the structural unit (I-1) being included in a polymer (A1);
• and
• a structural unit (II-1) represented by formula (2-1), formula (2-2) or both thereof, the structural unit (II-1) being included in the polymer (A1) or a polymer other than the polymer (A1);
• and
• [B] a solvent,
• wherein a content of the structural unit (I-1) in the polymer component [A] is from 0.5 to 50 mol % based on total structural units included in the polymer component [A],
• wherein
• R1 is a halogen atom, a nitro group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted monovalent alicyclic hydrocarbon group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted acyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group,
• R2 is —C(═O)—R3, —S(═O)2—R4, —R5—CN, or —R6—NO2, wherein R3 and R4 are each independently a hydrogen atom, an alkyl group, a fluoroalkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, a cyano group, a cyanomethyl group, an aralkyl group, or an aryl group, or R3 or R4 and R1 taken together represent a cyclic structure, and R5 and R6 are each independently a single bond, a methylene group, or an alkylene group having 2 to 5 carbon atoms,
• n is an integer from 1 to 3, in a case where R1 is present in a plurality of number, the plurality of R1s are each identical or different, and in a case where R2 is present in a plurality of number, the plurality of R2s are each identical or different,
• L1 is an (n+1)-valent linking group, and
• R is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group,
• wherein R′ is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group, Rf1 is a divalent linking group, and Rf2 is a linear or branched monovalent fluorohydrocarbon group having 2 to 8 carbon atoms or a monovalent alicyclic fluorohydrocarbon group having 4 to 8 carbon atoms.