Positive resist composition and patterning process

A positive resist composition at least comprising:

• (A) a resin component comprising a repeating unit (1′) selected from the following formulae:
• and one or more repeating units selected from the following general formulae (12), (13), (14), and (15), with the proviso that a+b+c+d+e=1, 0<a≦0.8, 0≦b≦0.6, 0≦c≦0.8, 0≦d≦0.6, 0≦e≦0.6, in the case of defining the ratio of the repeating unit represented by formula (1′) as a;
• the ratio of the repeating unit represented by formula (12) as b;
• the ratio of the repeating unit represented by formula (13) as c;
• the ratio of the repeating unit represented by formula (14) as d;
• and the ratio of the repeating unit represented by formula (15) as e;
• wherein R001 independently represents a hydrogen atom, a methyl group, or a trifluoromethyl group;
• R12 represents a hydrogen atom or a monovalent hydrocarbon group comprising, at least one group selected from a C1-15 fluorine-containing substituent, carboxy group, and hydroxy group;
• R13 represents a C3-15 monovalent hydrocarbon group comprising a —CO2— moiety;
• R14 represents a C7-15 polycyclichydrocarbon group or an alkyl group comprising a C7-15 polycyclichydrocarbon group;
• and R15 represents an acid labile group,
• (B) a photoacid generator generating sulfonic acid represented by the following general formula (8) upon exposure to a high energy beam;
• and
• (C) an onium salt where a cation is sulfonium represented by the following general formula (3), or ammonium represented by the following general formula (4);
• and an anion is represented by any one of the following general formulae (5) to (7),
• R201—CF2SO3−H+ (8)
• wherein R201 represents a C1-23 linear, branched, or cyclic alkyl, aralkyl, or aryl group that may optionally contain an ether group, an ester group, or a carbonyl group where a hydrogen atom or hydrogen atoms of the alkyl, aralkyl, or aryl group may be substituted with a halogen atom, a hydroxy group, a carboxy group, an amino group, or a cyano group, however, R201 does not represent a perfluoroalkyl group,
• wherein R101, R102, and R103 independently represent a C1-20 linear, branched, or cyclic alkyl, alkenyl, aralkyl, or aryl group that may optionally contain an ether group, an ester group, or a carbonyl group where a hydrogen atom or hydrogen atoms of the alkyl, alkenyl, aralkyl, or aryl group may be substituted with a halogen atom, a hydroxy group, a carboxy group, an amino group, or a cyano group;
• two or more among R101, R102, and R103 may be linked together to form a ring with the S in the formula (3);
• and
• R104, R105, R106, and R107 independently represent a hydrogen atom, or a C1-20 linear, branched, or cyclic alkyl, alkenyl, aralkyl, or aryl group that may optionally contain an ether group, an ester group, or a carbonyl group where a hydrogen atom or hydrogen atoms of the alkyl, alkenyl, aralkyl, or aryl group may be substituted with a halogen atom, a hydroxy group, a carboxy group, an amino group, or a cyano group;
• two or more among R104, R105, R106, and R107 may be linked together to form a ring with the N in the formula (4),
• wherein R108, R109, and R110 independently represent a hydrogen atom, a halogen atom except a fluorine atom, or a C1-20 linear, branched, or cyclic alkyl, alkenyl, aralkyl, or aryl group that may optionally contain an ether group, an ester group, or a carbonyl group where a hydrogen atom or hydrogen atoms of the alkyl, alkenyl, aralkyl, or aryl group may be substituted with a halogen atom, a hydroxy group, a carboxy group, an amino group, or a cyano group;
• two or more among R108, R109, and R110 may be linked together to form a ring,
• R111—SO3− (6)
• wherein R111 represents a C1-20 aryl group where a hydrogen atom or hydrogen atoms of the aryl group may be substituted with a halogen atom, a hydroxy group, a carboxy group, an amino group, or a cyano group;
• and hydrogen atom or hydrogen atoms of the aryl group may be substituted with a C1-20 linear, branched, or cyclic alkyl group,
• R112—COO− (7)
• wherein R112 represents a C1-20 linear, branched, or cyclic alkyl, alkenyl, aralkyl, or aryl group that may optionally contain an ether group, an ester group, or a carbonyl group where a hydrogen atom or hydrogen atoms of the alkyl, alkenyl, aralkyl, or aryl group may be substituted with a halogen atom, a hydroxy group, a carboxy group, an amino group, or a cyano group.