Resist composition

1. A resist composition comprising

a resin (A1) which has

a structural unit having a sultone ring and being represented by formula (Ix),

a structural unit represented by formula (II),

a structural unit having an acid-labile group, and

a structural unit having a lactone ring and being represented by formula (a3-2),

a resin (A2) which consists of a structural unit having a fluorine atom and a structural unit having a non-leaving hydrocarbon group, and has no structural unit having an acid-labile group and no structural unit having a lactone ring;

an acid generator, and

a weak acid inner salt represented by formula (D);

wherein R x represents a C 1 to C 6 alkyl group that may have a halogen atom, a hydrogen atom or a halogen atom,

A xx represents an oxygen atom, an —N(R c )— group or a sulfur atom,

A x represents a C 1 to C 18 divalent saturated hydrocarbon group where a methylene group may be replaced by an oxygen atom or a carbonyl group,

R 41 represents a C 1 to C 12 alkyl group that may have a halogen atom or a hydroxy group, a halogen atom, a hydroxy group, a cyano group, a C 1 to C 12 alkoxy group, a C 6 to C 12 aryl group, a C 7 to C 18 aralkyl group, a glycidyloxy group, a C 2 to C 12 alkoxycarbonyl or a C 2 to C 4 acyl group,

X 11 represents an oxygen atom, a sulfur atom or a methylene group,

ma represents an integer 0 to 9, and

R c represents a hydrogen atom or a C 1 to C 6 alkyl group;

wherein R 1 represents a hydrogen atom, a halogen atom or a C 1 to C 6 alkyl group that may have a halogen atom,

L 1 represents a single bond or *-L 2 -CO—O-(L 3 -CO—O) g —,

* represents a binding position to an oxygen atom,

L 2 and L 3 independently represent a C 1 to C 12 divalent hydrocarbon group,

g represents 0 or 1, and

R 3 represents a C 2 to C 8 linear alkyl group,

wherein L a5 represents *—O— or *—O—(CH 2 ) k3 —CO—O—, k3 represents an integer of 1 to 7,

* represents a binding position to a carbonyl group,

R a19 represents a hydrogen atom or a methyl group,

R a22 in each occurrence represents a carboxy group, a cyano group or a C 1 to C 4 aliphatic hydrocarbon group,

q1 represents an integer of 0 to 3, and

wherein R D1 and R D2 in each occurrence independently represent a C 1 to C 12 hydrocarbon group, a C 1 to C 6 alkoxy group, a C 2 to C 7 acyl group, a C 2 to C 7 acyloxy group, a C 2 to C 7 alkoxycarbonyl group, a nitro group or a halogen atom, and

m′ and n′ independently represent an integer of 0 to 4.

2. The resist composition according to claim 1 , wherein

L 1 is a single bond.

3. The resist composition according to claim 1 , wherein the structural unit having an acid-labile group is selected from the group consisting of a structural unit represented by formula (a1-0), a structural unit represented by formula (a1-1) and a structural unit represented by formula (a1-2);

wherein, L a01 represents —O— or *—O—(CH 2 ) k01 —CO—O—,

k01 represents an integer of 1 to 7,

* represents a binding position to —CO—,

R a01 represents a hydrogen atom or a methyl group, and

R a02 , R a03 and R a04 independently represent a C 1 to C 8 alkyl group, a C 3 to C 1 alicyclic hydrocarbon group or combination thereof,

L a1 and L a2 independently represent —O— or *—O—(CH 2 ) k1 —CO—O—,

k1 represents an integer of 1 to 7,

* represents a binding position to —CO—,

R a4 and R a5 independently represent a hydrogen atom or a methyl group,

R a6 and R a7 independently represent a C 1 to C 8 alkyl group, a C 3 to C 18 alicyclic hydrocarbon group or a combination thereof,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.