Resist composition and patterning process

A resist composition comprising a hypervalent iodine compound, an onium salt compound, a carboxy-containing compound, and a solvent, wherein

• the hypervalent iodine compound is at least one compound selected from hypervalent iodine compounds having the formulae (1) to (4):
• wherein m1 is 0, 1 or 2;
• when m1=0, n1 is 1, 2 or 3, n2 is 0, 1, 2, 3, 4 or 5 and 1≤n1+n2≤6;
• when m1=1, n1 is 1, 2 or 3, n2 is 0, 1, 2, 3, 4, 5, 6 or 7 and 1≤n1+n2≤8;
• when m1=2, n1 is 1, 2 or 3, n2 is 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9 and 1≤n1+n2≤10;
• n3 is 1 or 2, n4 is 0, 1, 2, 3 or 4, 1≤n3+n4≤5, n5 is 1 or 2, n6 is 0, 1, 2, 3 or 4, 1≤n5+n6≤5, n7 is 0, 1, 2, 3 or 4, n8 is 1, 2, 3 or 4,
• m2 is 0, 1 or 2;
• when m2=0, n9 is 0, 1, 2, 3 or 4;
• when m2=1, n9 is 0, 1, 2, 3, 4, 5 or 6;
• when m2=2, n9 is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
• R1 to R8 are each independently halogen or a C1-C10 hydrocarbyl group which may contain a heteroatom, R1 and R2, R3 and R4, R5 and R6, or R7 and R8 may bond together to form a ring with the carbon atoms to which they are attached and the intervenient atoms,
• R11 to R14 are each independently halogen or a C1-C40 hydrocarbyl group which may contain a heteroatom;
• when n2 is 2 or more, a plurality of R11 may be identical or different and a plurality of R11 may bond together to form a ring with the carbon atoms on the aromatic ring to which they are attached;
• when n4 is 2 or more, a plurality of R12 may be identical or different and a plurality of R12 may bond together to form a ring with the carbon atoms on the aromatic ring to which they are attached;
• when n6 is 2 or more, a plurality of R13 may be identical or different and a plurality of R13 may bond together to form a ring with the carbon atoms on the aromatic ring to which they are attached;
• when n7 is 2 or more, a plurality of R14 may be identical or different and a plurality of R14 may bond together to form a ring with the carbon atoms on the aromatic ring to which they are attached;
• R15 is a C1-C40 (n8)-valent hydrocarbon group or C2-C40 (n8)-valent heterocyclic group;
• when n8=2, R15 may also be an ether bond, carbonyl group, azo group, thioether bond, carbonate bond, carbamate bond, sulfinyl group, sulfonyl group or thioketone bond;
• some or all of the hydrogen atoms in the (n8)-valent hydrocarbon group or (n8)-valent heterocyclic group may be substituted by a heteroatom-containing moiety, some —CH2— in the (n8)-valent hydrocarbon group may be replaced by a heteroatom-containing moiety, R14 and R15 may bond together to form a ring with the carbon atoms to which they are attached and the intervenient atoms,
• R21 is halogen or a C1-C10 hydrocarbyl group which may contain a heteroatom,
• R22 is halogen or a C1-C40 hydrocarbyl group which may contain a heteroatom, when n9 is 2 or more, a plurality of R22 may be identical or different and a plurality of R22 may bond together to form a ring with the carbon atoms on the aromatic ring to which they are attached;
• R23 is carbonyl or a C1-C10 hydrocarbylene group which may contain a heteroatom,
• 1 and *2 each designate a point of attachment to a carbon atom on the aromatic ring in the formula, *1 and *2 being attached to adjoining carbon atoms on the aromatic ring,
• the onium salt compound consists of a sulfonium cation having the formula (5-1) or iodonium cation having the formula (5-2) and a halide ion, nitrate ion, hydrogensulfate ion, hydrogencarbonate ion, tetraphenylborate ion or anion having any one of the formulae (5-3) to (5-9):
• wherein R31 to R35 are each independently halogen or a C1-C30 hydrocarbyl group which may contain a heteroatom, R31 and R32 may bond together to form a ring with the sulfur atom to which they are attached,
• wherein k1 and k2 are each independently 1, 2, 3 or 4,
• Rf1 and Rf2 are each independently hydrogen, fluorine, or a C1-C6 fluorinated alkyl group, excluding that all Rf1 and Rf2 are hydrogen at the same time,
• R41 is hydrogen, halogen, hydroxy or a C1-C50 hydrocarbyl group which may contain a heteroatom,
• R42 is hydrogen, halogen, hydroxy or a C1-C50 hydrocarbyl group which may contain a heteroatom, exclusive of the group wherein hydrogen bonded to the carbon atom at α- or β-position relative to the sulfo group is substituted by fluorine or fluoroalkyl,
• R51 is hydrogen, halogen, hydroxy or a C1-C50 hydrocarbyl group which may contain a heteroatom,
• R52 is hydrogen, halogen, hydroxy or a C1-C50 hydrocarbyl group which may contain a heteroatom, exclusive of the group wherein hydrogen bonded to the carbon atom at α- or β-position relative to the carboxy group is substituted by fluorine or fluoroalkyl,
• R61 and R62 are each independently a C1-C50 hydrocarbyl group which may contain a heteroatom,
• R71 to R73 are each independently a C1-C50 hydrocarbyl group which may contain a heteroatom,
• R81 is fluorine or a C1-C10 fluorinated hydrocarbyl group which may contain hydroxy, ether bond or ester bond, R82 is hydrogen or a C1-C20 hydrocarbyl group which may contain hydroxy, ether bond or ester bond, R81 and R82 may bond together to form a ring with the atom to which they are attached.