Resist composition and patterning process

A resist composition comprising:

• (A) a resin containing (i) a repeating unit having an acid-labile group, and (ii) a repeating unit having an aromatic substituent, the repeating unit having an acid labile group shown by the following general formula (a1):
• where R1 represents a hydrogen atom or a methyl group;
• and X represents at least one acid-labile group selected from (I) and (II):
• (I) 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl, 1-isopropylcyclopentyl, 1-n-butylcyclopentyl, 1-sec-butylcyclopentyl, 1-tert-butylcyclopentyl, 1-cyclohexylcyclopentyl, 1-(4-methoxy-n-butyl)cyclopentyl, 1-methylcyclohexyl, 1-ethylcyclohexyl, 3-methyl-1-cyclopenten-3-yl, 3-ethyl-1-cyclopenten-3-yl, 3-methyl-1-cyclohexen-3-yl, and 3-ethyl-1-cyclohexen-3-yl;
• (II) groups shown by the following formulae:
• (B) a photo-acid generator that (III) consists of the photo-acid generator shown by the general formula (B-1);
• or (IV) includes a combination of the photo-acid generator shown by the general formula (B-1) and at least one other photo-acid generator selected from the photo-acid generators shown by general formula (B-2), general formula (B-3), and general formula (B-4);
• (C) a solvent;
• and
• (D) a fluorine-containing resin having at least one repeating unit selected from repeating units shown by the general formulas (D-1), (D-2), and (D-3), wherein the fluorine-containing resin is different from the resin of the component (A),
• General Formula (B-1):
• wherein W1 in the general formula (B-1) represents any of cyclic divalent hydrocarbon groups shown by the following formulae,
• wherein * represents an attachment point for a carbonyloxy group,
• wherein W2 represents a cyclic monovalent hydrocarbon group having 4 to 14 carbon atoms and not containing a heteroatom;
• Rf represents a divalent organic group shown by the above general formula;
• A1 and A2 each independently represent a hydrogen atom or a trifluoromethyl group;
• B1 and B2 each independently represent a hydrogen atom or a fluorine atom;
• * represents an attachment point for a carbonyloxy group;
• “m” represents an integer of 0 to 4;
• “n” represents an integer of 1;
• and M+ represents an onium cation that is at least one cation selected from the cations of the following formula group (Ill) and formula group (b2):
• (i) formula group (b1) is selected from the group consisting of:
• formula group (b2) is selected from the group consisting of:
• wherein A1 represents a hydrogen atom or a trifluoromethyl group;
• R21 represents a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms optionally containing an oxygen atom, a nitrogen-containing heterocyclic group, or a group represented by the following formula (i);
• MB+ represents the same onium cation as M+;
• where R31 and R32 each independently represent a hydrogen atom, or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• R31 and R32 optionally bond with each other to form a ring with a nitrogen atom bonded to R31 and R32;
• R33 represents a linear, branched, or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• wherein A2 represents a hydrogen atom or a trifluoromethyl group;
• R22, R23, and R24 each independently represent a hydrogen atom or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• “p” and “q” each independently represent an integer of 0 to 5;
• “r” represents an integer of 0 to 4;
• L represents a single bond, an ether group, or a linear, branched, or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• A3 and A4 each independently represent a hydrogen atom or a trifluoromethyl group, and are not both a hydrogen atom at the same time;
• and R25 represents a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms optionally containing an oxygen atom, a nitrogen-containing heterocyclic group, or a group shown by the formula (i);
• General Formulas (D-1), (D-2), and (D-3):
• wherein RA each independently represent a hydrogen atom or a methyl group;
• R51 and R52 each independently represent a hydrogen atom or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms;
• R53 represents a single bond or a linear or branched divalent hydrocarbon group having 1 to 5 carbon atoms;
• R54, R55, and R56 each independently represent a hydrogen atom, a linear, branched, or cyclic monovalent hydrocarbon group, fluorinated monovalent hydrocarbon group, or acyl group having 1 to 15 carbon atoms, or an acid-labile group;
• when R54, R55, and R56 represent the monovalent hydrocarbon group or the fluorinated monovalent hydrocarbon group, some carbon atoms thereof are optionally substituted with an ether group or a carbonyl group;
• R57 represents a linear, branched, or cyclic hydrocarbon group or fluorinated hydrocarbon group with a valency of (v+1) having 1 to 20 carbon atoms;
• and “v” represents an integer of 1 to 3.

A patterning process comprising the steps of:

• forming a resist film by coating a substrate with a resist composition and heat-treating;
• forming a protective film on the resist film;
• exposing the resist film with a high-energy beam by an immersion exposure that is performed with a liquid that is placed between the protective film and a projection lens, the liquid having a refractive index of 1.0 or more;
• and
• developing the exposed resist film using a developer,
• wherein the resist composition comprises:
• (A) a resin containing (i) a repeating unit having an acid-labile group, and (ii) a repeating unit having an aromatic substituent, the repeating unit having an acid labile group shown by the following general formula (a1):
• where R1 represents a hydrogen atom or a methyl group;
• and X represents at least one acid-labile group selected from (I) and (II):
• (I) 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl, 1-isopropylcyclopentyl, 1-n-butylcyclopentyl, 1-sec-butylcyclopentyl, 1-tert-butylcyclopentyl, 1-cyclohexylcyclopentyl, 1-(4-methoxy-n-butyl)cyclopentyl, 1-methylcyclohexyl, 1-ethylcyclohexyl, 3-methyl-1-cyclopenten-3-yl, 3-ethyl-1-cyclopenten-3-yl, 3-methyl-1-cyclohexen-3-yl, and 3-ethyl-1-cyclohexen-3-yl;
• (II) groups shown by the following formulae:
• (B) a photo-acid generator that (III) consists of the photo-acid generator shown by the general formula (B-1);
• or (IV) includes a combination of the photo-acid generator shown by the general formula (B-1) and at least one other photo-acid generator selected from the photo-acid generators shown by general formula (B-2), general formula (B-3), and general formula (B-4);
• (C) a solvent;
• and
• (D) a fluorine-containing resin having at least one repeating unit selected from repeating units shown by the general formulas (D-1), (D-2), and (D-3), wherein the fluorine-containing resin is different from the resin of the component (A),
• General Formula (B-1):
• wherein W1 represents a cyclic divalent hydrocarbon group having 4 to 12 carbon atoms and containing a heteroatom;
• W2 represents a cyclic monovalent hydrocarbon group having 4 to 14 carbon atoms and not containing a heteroatom;
• Rf represents a divalent organic group shown by the above general formula;
• A1 and A2 each independently represent a hydrogen atom or a trifluoromethyl group;
• B1 and B2 each independently represent a hydrogen atom or a fluorine atom;
• * represents an attachment point for a carbonyloxy group;
• “m” represents an integer of 0 to 4;
• “n” represents an integer of 1;
• and M+ represents an onium cation that is at least one cation selected from the cations of the following formula group (b1) and formula group (b2):
• (i) formula group (b1) is selected from the group consisting of:
• formula group (b2) is selected from the group consisting of:
• General Formulas (B-2), (B-3), and (B-4):
• wherein A1 represents a hydrogen atom or a trifluoromethyl group;
• R21 represents a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms optionally containing an oxygen atom, a nitrogen-containing heterocyclic group, or a group represented by the following formula (i);
• MB+ represents the same onium cation as M+;
• where R31 and R32 each independently represent a hydrogen atom, or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• R31 and R32 optionally bond with each other to form a ring with a nitrogen atom bonded to R31 and R32;
• R33 represents a linear, branched, or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• wherein A2 represents a hydrogen atom or a trifluoromethyl group;
• R22, R23, and R24 each independently represent a hydrogen atom or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• “p” and “q” each independently represent an integer of 0 to 5;
• “r” represents an integer of 0 to 4;
• L represents a single bond, an ether group, or a linear, branched, or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms optionally containing a heteroatom;
• A3 and A4 each independently represent a hydrogen atom or a trifluoromethyl group, and are not both a hydrogen atom at the same time;
• and R25 represents a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms optionally containing an oxygen atom, a nitrogen-containing heterocyclic group, or a group shown by the formula (i);
• General Formulas (D-1), (D-2), and (D-3):
• wherein RA each independently represent a hydrogen atom or a methyl group;
• R51 and R52 each independently represent a hydrogen atom or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms;
• R53 represents a single bond or a linear or branched divalent hydrocarbon group having 1 to 5 carbon atoms;
• R54, R55, and R56 each independently represent a hydrogen atom, a linear, branched, or cyclic monovalent hydrocarbon group, fluorinated monovalent hydrocarbon group, or acyl group having 1 to 15 carbon atoms, or an acid-labile group;
• when R54, R55, and R56 represent the monovalent hydrocarbon group or the fluorinated monovalent hydrocarbon group, some carbon atoms thereof are optionally substituted with an ether group or a carbonyl group;
• R57 represents a linear, branched, or cyclic hydrocarbon group or fluorinated hydrocarbon group with a valency of (v+1) having 1 to 20 carbon atoms;
• and “v” represents an integer of 1 to 3.