Resist composition and pattern forming method

Abstract

The present invention relates to a resist composition and a pattern forming method. The subject of the present invention is to provide a resist composition that exhibits particularly good mask size dependence (mask error coefficient: MEF) and size uniformity (CDU) in optical lithography using high-energy rays such as KrF excimer laser, electron beam, extreme ultraviolet rays as light sources, and to provide a pattern forming method using the resist composition. The solution to the problem is a resist composition, characterized in that it contains: (A) a resin containing repeating units having acid-labile groups and further containing at least one repeating unit having aromatic substituents, (B) a photoacid generator represented by the general formula (B‑1), and (C) a solvent. In the formula, W1 represents a cyclic divalent hydrocarbon group containing heteroatoms and having 4 to 12 carbon atoms. W2 represents a cyclic monovalent hydrocarbon group containing no heteroatoms and having 4 to 14 carbon atoms. Rf is a divalent organic group represented by the above general formula. M + represents an onium cation.

Description

Technical Field

[0001] The present invention relates to a resist composition and a patterning method. Background Art

[0002] With the high integration and high speed of LSIs, miniaturization has been rapidly progressing. In terms of the most advanced miniaturization technology, mass production has been achieved by ArF immersion lithography in which a liquid such as water is inserted between a projection lens and a substrate for exposure, and discussions are now underway on multiple exposure (multiple patterning) of ArF lithography, extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, and the like.

[0003] Among the chemically amplified resist materials used in the above lithography, a compound that decomposes upon exposure to generate an acid (hereinafter referred to as "acid generator") is used, and by optimizing the structure in the acid generator, acid diffusion can be suppressed and a high-resolution pattern can be formed. Such acid generators have been discussed, for example, those disclosed in Patent Documents 1 to 4.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2008-074843

[0007] [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2009-191054

[0008] [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2011-126869

[0009] [Patent Document 4] Japanese Unexamined Patent Application Publication No. 2012-072108 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] When further miniaturization is carried out, the acid generators discussed in the past are not necessarily sufficient in terms of many properties represented by resolution and resist pattern shape.

[0012] The present invention has been made to solve the above problems, and an object thereof is to provide a resist composition and a patterning method that exhibit good mask size dependence (mask error factor: MEF) and size uniformity (CDU) in optical lithography.

[0013] Solutions for Solving the Problems

[0014] In order to solve the above problems, the present invention provides a resist composition, which is characterized by containing: (A) a resin containing a repeating unit having an acid-labile group and further containing at least one repeating unit having an aromatic substituent, (B) a photoacid generator represented by the general formula (B-1), and (C) a solvent.

[0015] [Chemical formula 1]

[0016]

[0017] In the formula, W 1 represents a cyclic divalent hydrocarbon group containing a heteroatom having 4 to 12 carbon atoms. W 2 represents a cyclic monovalent hydrocarbon group having 4 to 14 carbon atoms and not containing a heteroatom. Rf is a divalent organic group represented by the above general formula, and A 1 , A 2 each independently represents a hydrogen atom or a trifluoromethyl group, and B 1 , B 2 each independently represents a hydrogen atom, a fluorine atom or a trifluoromethyl group, * represents a bond with the carbonyl oxygen atom. m represents an integer of 0 to 4, and n represents an integer of 0 to 1. M + represents an onium cation.

[0018] If it is such a resist composition of the present invention, it will exhibit good mask size dependence (mask error factor: MEF) and size uniformity (CDU) in optical lithography.

[0019] At this time, W in the above general formula (B-1) 1 is preferably a cyclic divalent hydrocarbon group having 6 to 12 carbon atoms and containing a lactone ring structure.

[0020] If it is such a resist composition, then during the acid generation after exposure, by arranging the lactone ring near the sulfonic acid group, acid diffusion can be more inhibited, so better mask size dependence and size uniformity can be exhibited.

[0021] Furthermore, W in the above general formula (B-1) 2 is preferably a polycyclic monovalent hydrocarbon group having 7 to 14 carbon atoms and not containing a heteroatom.

[0022] If it is such a resist composition, then by arranging a highly condensed hydrocarbon group at the end, appropriate solubility can be imparted, so better mask size dependence and size uniformity can be exhibited.

[0023] Furthermore, the Rf group in the above general formula (B-1) is preferably selected from the groups represented by the following formulas (Rf-1) to (Rf-6).

[0024] [Chemical formula 2]

[0025]

[0026] * Represents a bond with an atom of a carbonyl oxy group.

[0027] If it is such a resist composition, due to the effect of fluorine atoms in Rf, the solubility will be improved, and the sulfonic acid generated after exposure will have an appropriate acid strength, so better mask size dependence, LWR, and size uniformity can be exhibited.

[0028] Furthermore, in the resin of the component (A) described above, one of the repeating units having an aromatic substituent is preferably a repeating unit represented by the following formula (A-1).

[0029] [Chemical formula 3]

[0030]

[0031] In the formula, R A represents a hydrogen atom or a methyl group. R 61 represents a hydrogen atom, or a linear, branched, or cyclic hydrocarbon group having 1 to 10 carbon atoms and may contain a hetero atom. R 62 represents a linear, branched, or cyclic hydrocarbon group having 1 to 8 carbon atoms and may contain a hetero atom. t is an integer from 1 to 3, and u is an integer satisfying u ≤ 5 + 2s - t. s is 0 or 1. L 1 represents a single bond, or any one of -C(=O)O-, -C(=O)NH-.

[0032] By combining such a component (A) and the above-mentioned component (B), the resist composition of the present invention can exhibit better mask size dependence or size uniformity.

[0033] In the resin of the component (A) described above, one of the repeating units having an aromatic substituent is preferably a repeating unit represented by the following general formulas (A-2) to (A-4).

[0034] [Chemical formula 4]

[0035]

[0036] In the formula, R A are each independently a hydrogen atom or a methyl group, R 201 is a single bond, a phenylene group, -O-R 210 -, or -C(=O)-Z 2 -R 210 -. Z 2 is an oxygen atom or NH, R 210 is a linear, branched, or cyclic alkylene, alkenylene, or phenylene group having 1 to 6 carbon atoms, and may contain a carbonyl group (-CO-), an ester group (-COO-), an ether group (-O-), or a hydroxyl group. L 2 represents a single bond, or -Z3 -C(=O)-O-, Z 3 represents a divalent hydrocarbon group having 1 to 20 carbon atoms, which may be straight-chain, branched-chain or cyclic and may be substituted with heteroatoms. Z 1 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, -O-R 211 -, or -C(=O)-Z 4 -R 211 -. Z 4 is an oxygen atom or NH, R 211 is a straight-chain, branched-chain or cyclic alkylene, alkenylene or phenylene group having 1 to 6 carbon atoms, and may also contain a carbonyl group, an ester group, an ether group or a hydroxyl group. M - represents a non-nucleophilic counter ion. R 202 , R 203 , R 204 , R 205 , R 206 , R 207 , R 208 , R 209 each independently represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may be straight-chain and may be substituted with heteroatoms or may have heteroatoms inserted therein, or a branched-chain or cyclic monovalent hydrocarbon group having 3 to 20 carbon atoms. Also, R 202 and R 203 may also be bonded to each other to form a ring together with the sulfur atom in the formula, or R 204 , R 205 and R 206 any two or more of them, or R 207 , R 208 and R 209 any two or more of them may also be bonded to each other to form a ring together with the sulfur atom in the formula. However, the repeating units represented by the above general formulas (A-2) to (A-4) have one or more aromatic substituents.

[0037] By using such a component (A), the resist composition of the present invention can exhibit better mask size dependence or size uniformity.

[0038] The above resist composition preferably further contains a component (D), which is a resin different from the resin of the component (A) and is a fluororesin having at least one kind of repeating unit selected from the repeating units represented by the following formulas (D-1), (D-2) and (D-3).

[0039] [Chemical formula 5]

[0040]

[0041] In the formula, R A each independently is a hydrogen atom or a methyl group. R 51 and R 52Each independently is a hydrogen atom, or a monovalent hydrocarbon group having 1 to 10 carbon atoms in a linear, branched or cyclic form. R 53 is a single bond, or a divalent hydrocarbon group having 1 to 5 carbon atoms in a linear or branched form. R 54 , R 55 and R 56 Each independently is a hydrogen atom, or a monovalent hydrocarbon group, fluorinated monovalent hydrocarbon group or acyl group having 1 to 15 carbon atoms in a linear, branched or cyclic form, or an acid-labile group. R 54 , R 55 and R 56 When they are a monovalent hydrocarbon group or a fluorinated monovalent hydrocarbon group, a part of their carbon atoms may be substituted by an ether group or a carbonyl group. R 57 is a (v + 1)-valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms in a linear, branched or cyclic form. v is an integer of 1 to 3.

[0042] By further containing such a component (D), the resist composition of the present invention can improve the contact angle between the resist film surface and water, and suppress defects caused by residual infiltrated water, or the dissolution of an acid generator and a quencher. Further, the solubility of the resist film surface can be adjusted, and good size uniformity can be achieved.

[0043] Further, the present invention provides a pattern forming method, which is characterized by including the following steps: coating the above-mentioned resist composition on a substrate and performing a heat treatment to form a resist film, exposing the resist film with high-energy rays, and developing the exposed resist film using a developer.

[0044] If it is such a pattern forming method, good mask size dependence and size uniformity can be achieved in optical lithography.

[0045] In the pattern forming method of the present invention, the above-mentioned high-energy rays may be an ArF excimer laser having a wavelength of 193 nm or a KrF excimer laser having a wavelength of 248 nm.

[0046] Further, the above-mentioned exposure may be immersion exposure in which a liquid having a refractive index of 1.0 or more is inserted between the resist film and a projection lens, or pattern formation may be performed by further forming a protective film on the above-mentioned resist film and performing immersion exposure by inserting the liquid between the protective film and the projection lens.

[0047] If it is such a pattern forming method, better mask size dependence and size uniformity can be achieved in optical lithography.

[0048] In the pattern forming method of the present invention, the above-mentioned high-energy rays may also be an electron beam or extreme ultraviolet rays having a wavelength of 3 to 15 nm.

[0049] In such a pattern formation method, a pattern with good sensitivity, excellent MEF, and CDU can be formed.

[0050] Effects of the Invention

[0051] The resist composition of the present invention can form a resist pattern with particularly excellent mask size dependency (mask error factor: MEF) and LWR.

[0052] The present invention can provide a resist composition and a pattern formation method that exhibit particularly good mask size dependency (mask error factor: MEF) and size uniformity (CDU) especially in optical lithography using high-energy rays such as KrF excimer laser, electron beam, and extreme ultraviolet as light sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a diagram showing the 1 HNMR spectrum of PAG1 obtained in Example 1-1.

[0054] Figure 2 is a diagram showing the 19 FNMR spectrum of PAG1 obtained in Example 1-1.

[0055] Figure 3 is a diagram showing the 1 HNMR spectrum of PAG2 obtained in Example 1-2.

[0056] Figure 4 is a diagram showing the 19 FNMR spectrum of PAG2 obtained in Example 1-2. DETAILED DESCRIPTION

[0057] As described above, when further miniaturization is carried out, the acid generators explored in the past are not necessarily sufficient in terms of many properties represented by resolution and resist pattern shape.

[0058] As a result of repeated and in-depth studies by the inventors of the present application to achieve the above object, the following insight was obtained: A resist composition using an acid generator represented by the following formula (B-1) exhibits good mask size dependency (mask error factor: MEF) and size uniformity (CDU), and is extremely effective for precise microfabrication.

[0059] That is, the present invention is a resist composition characterized by containing: (A) a resin containing a repeating unit having an acid-labile group and further containing at least one repeating unit having an aromatic substituent, (B) a photoacid generator represented by the general formula (B-1), and (C) a solvent.

[0060] [Chemical Formula 6] ​​​​

[0061]

[0062] In the formula, W 1 represents a heteroatom-containing cyclic divalent hydrocarbon group having 4 to 12 carbon atoms. W 2 represents a cyclic monovalent hydrocarbon group having 4 to 14 carbon atoms and containing no heteroatom. Rf is a divalent organic group represented by the above general formula, and A 1 and A 2 each independently represent a hydrogen atom or a trifluoromethyl group, B 1 and B 2 each independently represent a hydrogen atom, a fluorine atom or a trifluoromethyl group, * represents a bond with the carbonyl oxygen atom. m represents an integer of 0 to 4, and n represents an integer of 0 to 1. M + represents an onium cation.

[0063] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto. In addition, in the following chemical formulas, there may often be enantiomers or diastereomers in terms of chemical structure, but unless otherwise specified, each chemical formula represents all of these stereoisomers in any case. Also, these stereoisomers can be used alone or in the form of a mixture.

[0064] [Resist composition]

[0065] The resist composition of the present invention contains: (A) a resin (base resin) containing a repeating unit having an acid-labile group and further containing at least one repeating unit having an aromatic substituent, (B) a photoacid generator represented by the general formula (B-1), and (C) a solvent. Optionally, a specific fluorine-containing resin different from the resin of the component (A), a quencher, a surfactant, or other components may be further contained as the component (D). Hereinafter, each component will be described.

[0066] [(A) Base resin]

[0067] In the resist composition of the present invention, the base resin (resin A) of the component (A) is a resin containing a repeating unit having an acid-labile group and containing at least one repeating unit having an aromatic substituent.

[0068] In the base resin of the component (A), examples of the repeating unit having an aromatic substituent include the following general formula (A-1).

[0069] [Chemical formula 7]

[0070]

[0071] In the formula, R A represents a hydrogen atom or a methyl group. R61 represents a hydrogen atom, or a linear, branched or cyclic hydrocarbon group with 1 to 10 carbon atoms which may contain heteroatoms inserted. R 62 represents a linear, branched or cyclic hydrocarbon group with 1 to 8 carbon atoms which may contain heteroatoms inserted. t is an integer from 1 to 3, and u is an integer satisfying u ≤ 5 + 2s - t. s is 0 or 1. L 1 represents a single bond, or any one of -C(=O)O-, -C(=O)NH-.

[0072] In the above formula, R 61 with 1 to 10 carbon atoms, preferably a linear, branched or cyclic hydrocarbon group with 1 to 5 carbon atoms which may contain heteroatoms inserted, examples include: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl, 1-methylcyclopentyl, 1-methylcyclohexyl, etc., but not limited thereto.

[0073] In the above formula, R 62 with 1 to 8 carbon atoms, preferably a linear, branched or cyclic hydrocarbon group with 1 to 5 carbon atoms which may contain heteroatoms inserted, in addition to the examples such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl, may also specifically include the following, etc., but not limited thereto.

[0074] [Chemical formula 8]

[0075]

[0076] Here, the dashed line represents an atomic bond (the same applies hereinafter).

[0077] The repeating unit represented by the aforementioned general formula (A-1) may specifically include the following, but not limited thereto.

[0078] [Chemical formula 9]

[0079]

[0080] In the formula, R A is the same as above.

[0081] [Chemical formula 10]

[0082]

[0083] In the formula, R A is the same as above.

[0084] [Chemical formula 11]

[0085]

[0086] In the base resin of component (A), the repeating units having an aromatic substituent can be further exemplified by the following general formulas (A-2) to (A-4).

[0087] [Chemical formula 12]

[0088]

[0089] In the formula, R A are each independently a hydrogen atom or a methyl group, and R 201 is a single bond, a phenylene group, -O-R 210 -, or -C(=O)-Z 2 -R 210 -. Z 2 is an oxygen atom or NH, and R 210 is a linear, branched or cyclic alkylene, alkenylene or phenylene group having 1 to 6 carbon atoms, and may also contain a carbonyl group (-CO-), an ester group (-COO-), an ether group (-O-) or a hydroxyl group. L 2 represents a single bond, or -Z 3 -C(=O)-O-, and Z 3 represents a linear, branched or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a heteroatom. Z 1 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, -O-R 211 -, or -C(=O)-Z 4 -R 211 -. Z 4 is an oxygen atom or NH, and R 211 is a linear, branched or cyclic alkylene, alkenylene or phenylene group having 1 to 6 carbon atoms, and may also contain a carbonyl group, an ester group, an ether group or a hydroxyl group. M - represents a non-nucleophilic counter ion. M - Examples include: hydroxide ion, carboxylate ion, halide ion, nitrate ion, nitrite ion, chlorate ion, bromate ion, methanesulfonate ion, p-toluenesulfonate ion, monomethyl sulfate ion, carbonate ion, sulfate ion, etc. R 202 、R 203 、R 204 、R 205 、R 206 、R 207 、R 208 、R 209Each independently represents a linear monovalent hydrocarbon group having 1 to 20 carbon atoms that may be substituted with a heteroatom or may have a heteroatom inserted therein, or a branched or cyclic monovalent hydrocarbon group having 3 to 20 carbon atoms. Specific examples include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, adamantyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, hexenyl, cyclohexenyl; aryl groups such as phenyl, naphthyl, thienyl; aralkyl groups such as benzyl, 1-phenylethyl, 2-phenylethyl, etc., and preferably an aryl group. Further, a part of the hydrogen atoms of these groups may also be substituted with heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms, etc., or heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, etc. may be inserted, and as a result, hydroxyl groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides, haloalkyl groups, etc. may also be formed or inserted. Further, R 202 and R 203 may also be bonded to each other and form a ring together with the sulfur atom in the formula, or R 204 、R 205 and R 206 Any two or more of them, or R 207 、R 208 and R 209 Any two or more of them may also be bonded to each other and form a ring together with the sulfur atom in the formula. However, the repeating units represented by the aforementioned general formulas (A-2) to (A-4) have one or more aromatic substituents.

[0090] In the above formula, when L 2 is -Z 3 -C(=O)-O-, the divalent hydrocarbon group having 1 to 20 carbon atoms represented by Z 3 that may be substituted with a heteroatom and is linear, branched or cyclic is specifically exemplified as follows, but is not limited thereto.

[0091] [Chemical formula 13]

[0092]

[0093] In the formula, the broken line represents an atomic bond.

[0094] In the above formula, R 202 and R 203 may also be bonded to each other and form a ring together with the sulfur atom in the formula, or R 204 、R 205 and R 206 Any two or more of them, or R 207 、R 208 and R 209 Any two or more of them may also be bonded to each other and form a ring together with the sulfur atom in the formula, and in this case, groups represented by the following formula, etc. may be cited.

[0095] [Chemical formula 14]

[0096]

[0097] In the formula, R 212 represents and exemplifies as R 201 or exemplifies as the above R 202 , R 203 , R 204 , R 205 , R 206 , R 207 , R 208 , R 209 are the same groups.

[0098] Specific structures of the sulfonium cations shown in the above general formulas (A-3) to (A-4) may include those shown below. However, the present invention is not limited thereto.

[0099] [Chemical formula 15]

[0100]

[0101] In the base resin of the component (A), the repeating unit having an acid-labile group may include the following general formula (a1).

[0102] [Chemical formula 16]

[0103]

[0104] In the formula, R 1 is a hydrogen atom or a methyl group. X represents an acid-labile group.

[0105] The repeating unit represented by the above general formula (a1) can provide a polymer that decomposes by the action of an acid to generate a carboxylic acid and becomes alkali-soluble. Various groups can be used as the acid-labile group X, and specifically, groups represented by the following general formulas (L1) to (L9), a tertiary alkyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trialkylsilyl group in which each alkyl group has 1 to 6 carbon atoms, an oxoalkyl group having 4 to 20 carbon atoms, etc. can be exemplified.

[0106] [Chemical formula 17]

[0107]

[0108] In the formula (L1), R L01 , R L02 represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. Specific examples include: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, n-octyl, norbornyl, tricyclodecyl, tetracyclododecyl, adamantyl, etc. R L03A monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms and which may have a heteroatom such as an oxygen atom, may be exemplified by a linear, branched or cyclic alkyl group, a group in which a part of hydrogen atoms thereof is substituted with a hydroxyl group, an alkoxy group, an oxo group, an amino group, an alkylamino group or the like, and specific examples thereof include the following substituted alkyl groups and the like.

[0109] [Chemical formula 18]

[0110]

[0111] R L01 and R L02 、R L01 and R L03 、R L02 and R L03 They may also be bonded to each other and together with the carbon atoms and oxygen atoms to which they are bonded form a ring. When forming a ring, R L01 、R L02 、R L03 each represents a linear or branched alkylene group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms.

[0112] In formula (L2), R L04 represents a tertiary alkyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trialkylsilyl group in which each alkyl group has 1 to 6 carbon atoms, an oxoalkyl group having 4 to 20 carbon atoms, or a group represented by the above general formula (L1). For the tertiary alkyl group, specific examples include: tert-butyl, tert-pentyl, 1,1-diethylpropyl, 2-cyclopentylpropan-2-yl, 2-cyclohexylpropan-2-yl, 2-(bicyclo[2.2.1]heptan-2-yl)propan-2-yl, 2-(adamantan-1-yl)propan-2-yl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, etc. For the trialkylsilyl group, specific examples include: trimethylsilyl, triethylsilyl, dimethyl-tert-butylsilyl, etc. For the oxoalkyl group, specific examples include: 3-oxocyclohexyl, 4-methyl-2-oxooxane-4-yl, 5-methyl-2-oxooxolane-5-yl, etc. l is an integer of 0 to 6.

[0113] In formula (L3), R L05Represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms which may be substituted, or an aryl group having 6 to 20 carbon atoms which may be substituted. In the case of the alkyl group which may be substituted, specific examples include: linear, branched or cyclic alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl, etc., those in which a part of the hydrogen atoms are substituted with a hydroxyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, an oxy group, an amino group, an alkylamino group, a cyano group, a mercapto group, an alkylthio group, a sulfo group, etc. In the case of the aryl group which may be substituted, specific examples include: phenyl, methylphenyl, naphthyl, anthryl, phenanthryl, pyrenyl, etc. In formula (L3), m is 0 or 1, n is any one of 0, 1, 2, 3, and is a number satisfying 2m + n = 2 or 3.

[0114] In formula (L4), R L06 Represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms which may be substituted, or an aryl group having 6 to 20 carbon atoms which may be substituted, and specific examples are the same as those of R L05 and so on. R L07 ~R L16 Each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 15 carbon atoms. Specific examples include: linear, branched or cyclic alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, etc., those in which a part of the hydrogen atoms are substituted with a hydroxyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, an oxy group, an amino group, an alkylamino group, a cyano group, a mercapto group, an alkylthio group, a sulfo group, etc. R L07 ~R L16 May also be bonded to each other to form a ring (for example, R L07 and R L08 , R L07 and R L09 , R L08 and R L10 , R L09 and R L10 , R L11 and R L12 , R L13 and R L14 etc.). In this case, it represents a divalent hydrocarbon group having 1 to 15 carbon atoms, and specific examples include those obtained by removing one hydrogen atom from those exemplified for the above monovalent hydrocarbon group. Also, those bonded to adjacent carbons among R L07 ~R L16 may be bonded to each other without passing through any substance to form a double bond (for example, R L07 and R L09 , R L09 and R L15 , RL13 With R L15 etc.).

[0115] In formula (L5), R L17 , R L18 , R L19 each independently represents a linear, branched or cyclic alkyl group having 1 to 15 carbon atoms. Specific examples include: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, n-octyl, 1-adamantyl, 2-adamantyl, etc.

[0116] In formula (L6), R L20 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may be substituted or an aryl group having 6 to 20 carbon atoms which may be substituted, and specific examples include and R L05 the same etc.

[0117] In formula (L7), R L21 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may be substituted or an aryl group having 6 to 20 carbon atoms which may be substituted, and specific examples include and R L05 the same etc.

[0118] R L24 represents a divalent group which forms a substituted or unsubstituted cyclopentane ring, cyclohexane ring or norbornane ring together with the carbon atom to which it is bonded. R L22 , R L23 each independently represents a hydrogen atom or a monovalent hydrocarbon group which is linear, branched or cyclic and has 1 to 10 carbon atoms. R L22 and R L23 may also be bonded to each other and form a ring together with the carbon atom to which they are bonded, and in this case, it represents a divalent group which forms a substituted or unsubstituted cyclopentane ring or cyclohexane ring. p represents 1 or 2.

[0119] In formula (L8), R L25 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may be substituted or an aryl group having 6 to 20 carbon atoms which may be substituted, and specific examples include and R L05 the same etc.

[0120] R L28 represents a divalent group which forms a substituted or unsubstituted cyclopentane ring, cyclohexane ring or norbornane ring together with the carbon atom to which it is bonded. R L26 , R L27 each independently represents a hydrogen atom or a monovalent hydrocarbon group which is linear, branched or cyclic and has 1 to 10 carbon atoms. R L26 and R L27They can also be bonded to each other and together with the carbon atoms to which they are bonded form a ring, in which case it represents a divalent group forming a substituted or unsubstituted cyclopentane ring or cyclohexane ring. q represents 1 or 2.

[0121] In formula (L9), R L29 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may be substituted, or an aryl group having 6 to 20 carbon atoms which may be substituted. Specific examples may include those similar to R L05 and the like.

[0122] R L32 represents a divalent group which together with the carbon atom to which it is bonded forms a substituted or unsubstituted cyclopentane ring, cyclohexane ring or norbornane ring. R L30 , R L31 each independently represents a hydrogen atom or a monovalent hydrocarbon group which is linear, branched or cyclic and has 1 to 10 carbon atoms. R L30 and R L31 can also be bonded to each other and together with the carbon atoms to which they are bonded form a ring, in which case it represents a divalent group forming a substituted or unsubstituted cyclopentane ring or cyclohexane ring.

[0123] Among the acid-labile groups represented by the above formula (L1), specific examples of the linear or branched ones may include the following groups.

[0124] [Chemical formula 19]

[0125]

[0126] Among the acid-labile groups represented by the above formula (L1), specific examples of the cyclic ones may include: tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl, tetrahydropyran-2-yl, 2-methyltetrahydropyran-2-yl, etc.

[0127] Specific examples of the acid-labile group of the above formula (L2) may include: tert-butoxycarbonyl, tert-butoxycarbonylmethyl, tert-pentyloxycarbonyl, tert-pentyloxycarbonylmethyl, 1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl, 1-ethylcyclopentyloxycarbonyl, 1-ethylcyclopentyloxycarbonylmethyl, 1-ethyl-2-cyclopentenyl-oxycarbonyl, 1-ethyl-2-cyclopentenyl-oxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl, 2-tetrahydropyranyloxycarbonylmethyl, 2-tetrahydrofuryloxycarbonylmethyl, etc.

[0128] Specific examples of the acid-labile group of the above formula (L3) include: 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, 3-ethyl-1-cyclohexen-3-yl, and the like.

[0129] The acid-labile group of the above formula (L4) is particularly preferably a group represented by the following formulas (L4-1) to (L4-4).

[0130] [Chemical formula 20]

[0131]

[0132] In the above formulas (L4-1) to (L4-4), the broken line indicates the bonding position and bonding direction. R L41 Each independently represents a monovalent hydrocarbon group such as a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. Specific examples include: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl, and the like.

[0133] In the above formulas (L4-1) to (L4-4), enantiomers and diastereomers may exist, and the above formulas (L4-1) to (L4-4) represent all of these stereoisomers. These stereoisomers can be used alone or in a mixture.

[0134] For example, the above formula (L4-3) represents a mixture of one or two groups selected from the groups represented by the following formulas (L4-3-1) and (L4-3-2).

[0135] [Chemical formula 21]

[0136]

[0137] Also, the above formula (L4-4) represents a mixture of one or more than two groups selected from the groups represented by the following formulas (L4-4-1) to (L4-4-4).

[0138] [Chemical formula 22]

[0139]

[0140] The above general formulas (L4-1) to (L4-4), (L4-3-1), (L4-3-2) and (L4-4-1) to (L4-4-4) also represent their enantiomers and mixtures of enantiomers.

[0141] In addition, by making the bonding directions of (L4-1) to (L4-4), (L4-3-1), (L4-3-2) and (L4-4-1) to (L4-4-4) relative to the bicyclo[2.2.1]heptane ring be on the exo side, high reactivity in the acid-catalyzed elimination reaction can be achieved (see Japanese Patent Application Laid-Open No. 2000-336121). When manufacturing monomers having a tertiary exo-alkyl group with a bicyclo[2.2.1]heptane skeleton as a substituent, there may sometimes be a case where a monomer substituted with an endo-alkyl group represented by the following general formulas (L4-1-endo) to (L4-4-endo) is contained. In order to achieve good reactivity, the exo ratio should be 50% or more, and more preferably 80% or more.

[0142] [Chemical formula 23]

[0143]

[0144] In the formula, R 13 represents the same group as exemplified for R L41

[0145] See Japanese Patent Application Laid-Open No. 2000-336121.

[0146] Specific examples of the acid-labile group of the above formula (L4) include the following groups.

[0147] [Chemical formula 24]

[0148]

[0149] Furthermore, specific examples of the tertiary alkyl group having 4 to 20 carbon atoms, the trialkylsilyl group having 1 to 6 carbon atoms in each alkyl group, and the oxoalkyl group having 4 to 20 carbon atoms include the same as those exemplified for R L04

[0150] Specific examples of the acid-labile group of the above formula (L5) include: tert-butyl, tert-pentyl, and the following groups.

[0151] [Chemical formula 25]

[0152]

[0153] Specific examples of the acid-labile group of the above formula (L6) include the following groups.

[0154] [Chemical formula 26] ​​

[0155]

[0156] Specific examples of the acid-labile group of the above formula (L7) may include the following groups.

[0157] [Chemical formula 27]

[0158]

[0159] Specific examples of the acid-labile group of the above formula (L8) may include the following groups.

[0160] [Chemical formula 28]

[0161]

[0162] Specific examples of the acid-labile group of the above formula (L9) may include the following groups.

[0163] [Chemical formula 29]

[0164]

[0165] Specific examples of the monomer represented by the foregoing general formula (a1) may include the following, but are not limited thereto.

[0166] [Chemical formula 30]

[0167]

[0168] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0169] [Chemical formula 31]

[0170]

[0171] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0172] [Chemical formula 32]

[0173]

[0174] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0175] [Chemical formula 33]

[0176]

[0177] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0178] Further, in the base resin of the component (A), in addition to using the unit represented by the above general formula (a1), monomers represented by the following general formulas (a2) to (a4) are preferably used as needed.

[0179] [Chemical formula 34]

[0180]

[0181] In the formula, R 1 is the same as above. R 5 and R 6 each independently represent a hydrogen atom or a hydroxyl group. Y represents a substituent having a lactone structure or a substituent having a sultone structure. Z represents a hydrogen atom, or a substituent of a fluorinated hydrocarbon group having 1 to 15 carbon atoms or a fluorinated alcohol having 1 to 15 carbon atoms.

[0182] Specific examples of the unit represented by the general formula (a2) include, but are not limited to, the following.

[0183] [Chemical formula 35]

[0184]

[0185] Specific examples of the monomer represented by the general formula (a3) include, but are not limited to, the following.

[0186] [Chemical formula 36]

[0187]

[0188] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0189] [Chemical formula 37]

[0190]

[0191] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0192] [Chemical formula 38]

[0193]

[0194] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0195] [Chemical formula 39]

[0196]

[0197] In the formula, R 1 represents a hydrogen atom or a methyl group.

[0198] Specific examples of the repeating unit represented by the general formula (a4) are as follows, but are not limited thereto.

[0199] [Chemical Formula 40]

[0200]

[0201] In the resist composition of the present invention, monomers having a carbon-carbon double bond other than the above may also be used, such as: substituted acrylate esters such as methyl methacrylate, methyl crotonate, dimethyl maleate, dimethyl itaconate; unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid; cyclic olefins such as norbornene, norbornene derivatives, tetracyclo[4.4.0.1 2,5 .17 7,10 dodecene derivatives; unsaturated acid anhydrides such as itaconic anhydride, α-methylene-γ-butyrolactone, α-methylstyrene, and other monomers.

[0202] The weight average molecular weight (Mw) of the resin A (the base resin of the component (A)) is preferably 1,000 to 500,000, more preferably 3,000 to 100,000. If it is within the above range, there is no concern about a decrease in etching resistance or a decrease in resolution due to the inability to ensure the contrast before and after exposure. In addition, in the present invention, Mw is a polystyrene conversion measurement value obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylacetamide (DMF) as a solvent.

[0203] In addition, when the molecular weight distribution (Mw / Mn) in the resin A is broad, both low molecular weight and high molecular weight polymers exist, so there is a concern about observing foreign substances on the pattern or deteriorating the pattern shape after exposure. Therefore, since such effects of molecular weight and molecular weight distribution tend to become larger as the pattern rules are miniaturized, in order to obtain a resist composition suitable for fine pattern sizes, the molecular weight distribution of the resin A is preferably 1.0 to 2.0, and particularly preferably a narrow dispersion of 1.0 to 1.5.

[0204] Examples of the method for synthesizing resin A include a method of heating and polymerizing monomers having unsaturated bonds for obtaining repeating units represented by formula (a1) and, if necessary, repeating units represented by formulas (a2) to (a4) or other repeating units in an organic solvent by adding a radical initiator. Examples of the organic solvent used in the polymerization include toluene, benzene, THF, diethyl ether, dioxane, methyl ethyl ketone, γ-butyrolactone, propylene glycol monomethyl ether acetate (PGMEA), etc. Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide, etc. The reaction temperature is preferably 50 to 150°C, more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours. The acid-labile group can be directly used as introduced into the monomer, or can be protected or partially protected after polymerization. Also, in order to adjust the molecular weight, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol can be used to carry out the polymerization. At this time, the addition amount of the chain transfer agent relative to all the monomers to be polymerized is preferably an amount represented by a molar ratio of 0.01 to 10.

[0205] In resin A, the ideal content ratio of each repeating unit derived from each monomer can be set, for example, within the ranges shown below, but is not limited thereto.

[0206] (I) The repeating unit represented by formula (a1) preferably contains 1 to 99 mol%, more preferably 20 to 95 mol%, still more preferably 30 to 90 mol%, and if necessary,

[0207] (II) The repeating unit represented by formula (A-1) preferably contains 1 to 70 mol%, more preferably 5 to 60 mol%, still more preferably 10 to 60 mol%,

[0208] (III) At least one selected from the repeating units represented by formulas (A-2) to (A-4) preferably contains 1 to 40 mol%, more preferably 3 to 35 mol%, still more preferably 5 to 30 mol%,

[0209] (IV) At least one selected from the repeating units represented by formulas (a2) to (a4) preferably contains 0 to 99 mol%, more preferably 0 to 90 mol%, still more preferably 0 to 70 mol%,

[0210] (V) Other repeating units preferably contain 0 to 99 mol%, more preferably 0 to 70 mol%, still more preferably 0 to 50 mol%.

[0211] In addition, the base resin of the component (A) may also contain two or more resins having different composition ratios, molecular weights, or molecular weight distributions. Depending on the need, in addition to the resin containing repeating units having acid-labile groups, it may further contain a resin that does not contain the repeating unit represented by the formula (a1).

[0212] [(B) Photoacid generator]

[0213] The resist composition of the present invention contains a photoacid generator represented by the following formula (B-1) as the component (B).

[0214] [Chemical formula 41]

[0215]

[0216] In the formula, W 1 represents a divalent heterocyclic hydrocarbon group having 4 to 12 carbon atoms and containing a heteroatom. W 2 represents a monovalent cyclic hydrocarbon group having 4 to 14 carbon atoms and not containing a heteroatom. Rf is a divalent organic group represented by the above general formula, and A 1 , A 2 each independently represents a hydrogen atom or a trifluoromethyl group, and B 1 , B 2 each independently represents a hydrogen atom, a fluorine atom, or a trifluoromethyl group, * represents a bond with the carbonyl oxygen atom. m represents an integer of 0 to 4, and n represents an integer of 0 to 1. M + represents an onium cation.

[0217] Specific examples of the divalent heterocyclic hydrocarbon group having 4 to 12 carbon atoms and containing a heteroatom represented by W 1 are as follows.

[0218] [Chemical formula 42]

[0219]

[0220] * represents a bond with the oxycarbonyl group.

[0221] Particularly preferred examples of W 1 include a divalent cyclic hydrocarbon group containing a lactone ring structure, and particularly preferred is a divalent cyclic hydrocarbon group having 6 to 12 carbon atoms and containing a lactone ring structure. When the acid is generated after exposure, by arranging the lactone ring near the sulfonic acid group, acid diffusion can be further suppressed.

[0222] Specific examples of the monovalent cyclic hydrocarbon group having 4 to 14 carbon atoms and not containing a heteroatom represented by W 2 are as follows.

[0223] [Chemical formula 43]

[0224]

[0225] The broken line represents an atomic bond.

[0226] W 2 is preferably a polycyclic monovalent hydrocarbon group having 7 to 14 carbon atoms and no heteroatoms. Regarding W 2 particularly preferred examples include adamantyl. By arranging a highly condensed hydrocarbon group at the terminal, appropriate solubility can be imparted.

[0227] Rf is a divalent organic group represented by the above general formula. Here, A 1 and A 2 each independently represent a hydrogen atom or a trifluoromethyl group, B 1 and B 2 each independently represent a hydrogen atom, a fluorine atom or a trifluoromethyl group, * represents an atomic bond with a carbonyl oxy group. m represents an integer from 0 to 4, and n represents an integer from 0 to 1. It is preferably m + n>0.

[0228] The Rf group is particularly preferably selected from the groups represented by the following formulas (Rf-1) to (Rf-6).

[0229] [Chemical formula 44]

[0230]

[0231] * represents an atomic bond with a carbonyl oxy group.

[0232] If the photoacid generator represented by the formula (B-1) has such an Rf, the solubility will be improved due to the effect of the fluorine atom, and the sulfonic acid generated after exposure will have an appropriate acid strength, so it is more ideal.

[0233] Specific examples of the structure of the anion part of the photoacid generator represented by the formula (B-1) are shown below, but are not limited thereto.

[0234] [Chemical formula 45]

[0235]

[0236] [Chemical formula 46]

[0237]

[0238] [Chemical formula 47]

[0239]

[0240] In the formula (B-1), the onium cation represented by M + is preferably at least one selected from the cations represented by the following formula (b1) and formula (b2).

[0241] [Chemical formula 48]

[0242]

[0243] In formulas (b1) and (b2), R 41 ~R 45 are each independently a linear, branched or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms which may also contain a heteroatom. Further, any two of R 41 , R 42 and R 43 may also be bonded to each other to form a ring together with the sulfur atom in the formula.

[0244] Examples of the monovalent hydrocarbon group represented by R 41 ~R 45 include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, adamantyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, hexenyl, cyclohexenyl; aryl groups such as phenyl, naphthyl, thienyl; aralkyl groups such as benzyl, 1-phenylethyl, 2-phenylethyl, etc. Among them, an aryl group is preferred. Further, a part of the hydrogen atoms of the aforementioned monovalent hydrocarbon group may also be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of the carbon atoms of these groups may also be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, it may also contain a hydroxyl group, a cyano group, a carbonyl group, an ether group, an ester group, a sulfonate group, a carbonate group, a lactone ring, a sultone ring, a carboxylic anhydride, a haloalkyl group, etc.

[0245] Examples of the sulfonium cation represented by formula (b1) include those shown below, but are not limited thereto.

[0246] [Chemical formula 49]

[0247]

[0248] [Chemical formula 50]

[0249]

[0250] [Chemical formula 51]

[0251]

[0252] [Chemical formula 52]

[0253]

[0254] [Chemical formula 53]

[0255]

[0256] [Chemical formula 54]

[0257]

[0258] [Chemical formula 55]

[0259]

[0260] [Chemical formula 56]

[0261]

[0262] Examples of the sulfonium cation represented by formula (b2) include, but are not limited to, those shown below.

[0263] [Chemical formula 57]

[0264]

[0265] In addition, in order to finely adjust the lithography performance, the resist composition of the present invention may further contain other photoacid generators other than the aforementioned photoacid generator. Regarding other photoacid generators, any compound that generates an acid upon irradiation with high-energy rays may be used, and those known in resist compositions, particularly chemically amplified resist compositions, may be used. Ideal examples of other photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethanes, N-sulfonyloxyimides, oxime-O-sulfonate type acid generators, etc. They may be used alone or in combination of two or more. The acid generated from other photoacid generators is preferably a strong acid such as sulfonic acid, (bis(perfluoroalkylsulfonyl))imide, (tris(perfluoromethylsulfonyl))methylide, or a weak acid such as carboxylic acid.

[0266] Specific examples of other photoacid generators include, for example, the following formulas (B-2), (B-3), and (B-4).

[0267] [Chemical formula 58]

[0268]

[0269] In formula (B-2), A 1 is a hydrogen atom or a trifluoromethyl group. R 21 is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms that may contain an oxygen atom, a nitrogen-containing heterocyclic group, or a group represented by the following formula (i). M + is an iodonium cation.

[0270] [Chemical formula 59]

[0271]

[0272] In formula (i), R 31 and R 32 are each independently a hydrogen atom or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms that may contain a heteroatom. R 31 and R 32They can also be bonded to each other and together with the nitrogen atoms to which they are bonded to form a ring. R 33 is a divalent hydrocarbon group having 1 to 20 carbon atoms, which may be linear, branched or cyclic and may also contain heteroatoms.

[0273] R 21 Examples of the monovalent hydrocarbon group represented by R, which may also contain an oxygen atom, include: alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, 1-adamantyl, 1-adamantylmethyl; groups containing a steroid structure; oxoalkyl groups such as 2-oxocyclopentyl, 2-oxocyclohexyl, 4-oxocyclohexyl, 2-oxopropyl, 2-oxoethyl, 2-cyclopentyl-2-oxoethyl, 2-cyclohexyl-2-oxoethyl, 2-(4-methylcyclohexyl)-2-oxoethyl, 4-oxatricyclo[4.2.1.0 3,7 nonane-5-one-9-yl, 4-oxo-1-adamantyl; aryl groups such as phenyl, 1-naphthyl, 2-naphthyl, anthryl, thienyl, 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, 3-tert-butoxyphenyl and other alkoxyphenyls, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-tert-butylphenyl, 4-n-butylphenyl, 2,4-dimethylphenyl and other alkylphenyls, methylnaphthyl, ethylnaphthyl and other alkylnaphthyls, methoxynaphthyl, ethoxynaphthyl and other alkoxynaphthyls, dimethylnaphthyl, diethylnaphthyl and other dialkylnaphthyls, dimethoxynaphthyl, diethoxynaphthyl and other dialkoxynaphthyls; aralkyl groups such as benzyl, 1-phenylethyl, 2-phenylethyl; aryl oxoalkyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, 2-(2-naphthyl)-2-oxoethyl and other 2-aryl-2-oxoethyls. Other examples include vinyl, isopropenyl, etc.

[0274] R 21 Examples of the nitrogen-containing heterocyclic group represented by R include: aziridine, pyrrolidine, piperidine, morpholine, pyrrole, pyridine, azetine, oxazole, isoxazole, thiazole, isothiazole, imidazole, pyrazole, pyridazine, pyrimidine, pyrazine, pyrroline, 2-imidazoline, imidazolidine, 3-pyrazoline, pyrazolidine, piperazine, triazine, oxadiazine, dithiazine, indole, isoindole, quinoline, isoquinoline, cinnoline, phthalazine, quinazoline, quinoxaline, 1,8-naphthyridine, purine, pteridine, indolizine, carbazole, acridine, phenazine, phenanthridine, 1,10-phenanthroline, phenoxazine, indoline, isoindoline, quinuclidine, benzo[e]indole, benzo[cd]indole.

[0275] As R 21Preferred examples include: tert-butyl, cyclohexyl, 1-adamantyl, 1-adamantylmethyl, 4-oxatricyclo[4.2.1.0 3,7 nonan-5-one-9-yl, 4-oxo-1-adamantyl, an alkyl group having a steroid structure, etc.

[0276] In formula (i), examples of the monovalent hydrocarbon group represented by R 31 and R 32 include: alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, adamantyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, hexenyl, cyclohexenyl; aryl groups such as phenyl, naphthyl, thienyl; aralkyl groups such as benzyl, 1-phenylethyl, 2-phenylethyl. In addition, in the aforementioned hydrocarbon groups, some of the hydrogen atoms may be substituted with the aforementioned monovalent hydrocarbon group, or a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, it may also contain a hydroxyl group, a cyano group, a carbonyl group, an ether group, an ester group, a sulfonate group, a carbonate group, a lactone ring, a sultone ring, a carboxylic anhydride, a haloalkyl group, etc.

[0277] When R 31 and R 32 are bonded to each other and form a ring together with the nitrogen atom to which they are bonded, specific examples of the ring include: aziridine, pyrrolidine, piperidine, morpholine, pyrrole, pyridine, azetidine, oxazole, isoxazole, thiazole, isothiazole, imidazole, pyrazole, pyridazine, pyrimidine, pyrazine, pyrroline, 2-imidazoline, imidazolidine, 3-pyrazoline, pyrazolidine, piperazine, triazine, oxadiazine, dithiazine, indole, isoindole, quinoline, isoquinoline, cinnoline, phthalazine, quinazoline, quinoxaline, 1,8-naphthyridine, purine, pteridine, indolizine, carbazole, acridine, phenazine, phenanthridine, 1,10-phenanthroline, phenoxazine, indoline, isoindoline, quinuclidine, benzo[e]indole, benzo[cd]indole, etc. Further, some of the hydrogen atoms of these rings may be substituted with the aforementioned hydrocarbon group, or a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, or some of the carbon atoms of these rings may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, it may also contain a hydroxyl group, a cyano group, a carbonyl group, an ether group, an ester group, a sulfonate group, a carbonate group, a lactone ring, a sultone ring, a carboxylic anhydride, a haloalkyl group, etc.

[0278] In formula (i), R 33Examples of the divalent hydrocarbon group represented include: methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl, pentadecane-1,15-diyl, hexadecane-1,16-diyl, heptadecane-1,17-diyl and other linear alkanediyls; branched alkanediyls formed by adding side chains such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl to the aforementioned linear alkanediyls; saturated cyclic hydrocarbon groups such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, adamantanediyl; unsaturated cyclic divalent hydrocarbon groups such as phenylene, naphthylene. Further, some of the hydrogen atoms of these groups may also be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms, or some of the carbon atoms of these groups may be inserted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and as a result, it may also contain hydroxyl groups, cyano groups, carbonyl groups, ether groups, ester groups, sulfonate groups, carbonate groups, lactone rings, sultone rings, carboxylic anhydrides, haloalkyl groups, etc.

[0279] Specific examples of the structure of the anionic part of the photoacid generator represented by formula (B-2) are shown below, but are not limited thereto. Further, in the following formula, A 1 is the same as the aforementioned.

[0280] [Chemical formula 60]

[0281]

[0282] [Chemical formula 61]

[0283]

[0284] In formula (B-2), M + represents that the onium cation is preferably at least one selected from the cations represented by the aforementioned formula (b1) and formula (b2).

[0285] In formula (B-3), A 2 is a hydrogen atom or a trifluoromethyl group. R 22 , R 23 and R 24 are each independently a hydrogen atom, or a linear, branched or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms. p and q are each independently an integer from 0 to 5. r is an integer from 0 to 4. L is a single bond, an ether group, or a linear, branched or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms which may contain heteroatoms.

[0286] R 22 , R23 and R 24 Examples of the monovalent hydrocarbon group represented by 24 include: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, tricyclo[5.2.1.0 2,6 decyl, adamantyl and other alkyl groups. Further, some of the hydrogen atoms of these groups may also be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, or some of the carbon atoms of these groups may also be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may also contain hydroxyl groups, cyano groups, carbonyl groups, ether groups, ester groups, sulfonate groups, carbonate groups, lactone rings, sultone rings, carboxylic anhydrides, haloalkyl groups, etc. R 22 , R 23 and R 24 are preferably methyl, methoxy, tert-butyl, tert-butoxy, etc.

[0287] In formula (B-3), examples of the divalent hydrocarbon group represented by L include the same ones as those exemplified for R 33 and in addition, it may also be a combination of two or more of these groups. Further, some of the hydrogen atoms of these groups may also be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, or some of the carbon atoms of these groups may also be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may also contain hydroxyl groups, cyano groups, carbonyl groups, ether groups, ester groups, sulfonate groups, carbonate groups, lactone rings, sultone rings, carboxylic anhydrides, haloalkyl groups, etc.

[0288] Examples of the photoacid generator represented by formula (B-3) include those shown below, but are not limited thereto. In addition, in the following formula, A 2 is the same as the foregoing.

[0289] [Chemical formula 62]

[0290]

[0291] [Chemical formula 63]

[0292]

[0293] (B) The photoacid generator may further contain the compound represented by the above formula (B-4). In formula (B-4), A 3 and A 4 are each independently a hydrogen atom or a trifluoromethyl group, and they are not both hydrogen atoms at the same time. R 25is a monovalent hydrocarbon group having 1 to 35 carbon atoms, which may also contain an oxygen atom, and is linear, branched or cyclic, or a nitrogen-containing heterocyclic group or a group represented by the aforementioned formula (i). M + is the same as the aforementioned onium cation.

[0294] Specific examples of the structure of the anion moiety of the photoacid generator represented by the formula (B-4) are shown below, but are not limited thereto.

[0295] [Chemical formula 64]

[0296]

[0297] [Chemical formula 65]

[0298]

[0299] Among the above-mentioned other photoacid generators, compounds having a fluorine atom-containing structure represented by trifluoromethyl in the anion structure part have high hydrophobicity and little dissolution in infiltrating water. Also, due to the presence of a fluorine atom-containing structure, the solvent solubility is high, and when developing with an organic solvent, the residue after development can be reduced. Thereby, defects after development can be reduced, and it is suitable as a resist composition for ArF immersion lithography.

[0300] As specific examples other than the aforementioned photoacid generators, for example, compounds described in paragraphs

[0122] to

[0142] of Japanese Patent Application Laid-Open No. 2008-111103 can be cited. Particularly preferred examples include compounds described in paragraphs

[0088] to

[0092] of Japanese Patent Application Laid-Open No. 2014-001259, compounds described in paragraphs

[0015] to

[0017] of Japanese Patent Application Laid-Open No. 2012-41320, compounds described in paragraphs

[0015] to

[0029] of Japanese Patent Application Laid-Open No. 2012-106986, and the like. Among the partially fluorinated sulfonic acid-generating photoacid generators described in the aforementioned publications, particularly in ArF lithography, the strength and diffusion distance of the acid generated are appropriate, and they can be desirably used.

[0301] The content of the photoacid generator of the component (B) is preferably 0.1 to 50 parts by mass, more preferably 0.2 to 40 parts by mass, and still more preferably 0.3 to 35 parts by mass with respect to 100 parts by mass of the base resin of the component (A). If it is within the aforementioned range, the resolution will not deteriorate, and there will be no concern about the problem of foreign matter generation during development and peeling of the resist film. In addition, when adding the compound represented by the formula (B-4), the content is preferably 0 to 50% by mass in the photoacid generator of the component (B).

[0302] [(C) Solvent]

[0303] The resist composition of the present invention contains a solvent as the component (C). Examples of the aforementioned solvent include ketones such as cyclohexanone and methyl-2-n-amyl ketone described in paragraphs

[0144] to

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monoter-butyl ether acetate; lactones such as γ-butyrolactone; and ketols such as diacetone alcohol; and a mixed solvent thereof. When an acetal-based acid-labile group is used, in order to accelerate the deprotection reaction of the acetal, a high-boiling alcohol-based solvent may also be added. Specifically, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, etc. may also be added.

[0304] The content of the solvent of the component (C) is preferably 100 to 10,000 parts by mass, more preferably 300 to 8,000 parts by mass, relative to 100 parts by mass of the base resin of the component (A).

[0305] [(D) Fluororesin]

[0306] The resist composition of the present invention may also contain a resin different from the aforementioned resin A and a fluororesin containing at least one kind selected from the repeating units represented by the following formulas (D-1), (D-2), and (D-3).

[0307] [Chemical formula 66]

[0308]

[0309] In the formula, R A is a hydrogen atom or a methyl group. R 51 and R 52 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms in a straight-chain, branched-chain, or cyclic form. R 53 is a single bond or a divalent hydrocarbon group having 1 to 5 carbon atoms in a straight-chain or branched-chain form. R 54 , R 55 and R 56 are each independently a hydrogen atom, or a monovalent hydrocarbon group having 1 to 15 carbon atoms in a straight-chain, branched-chain, or cyclic form, a fluorinated monovalent hydrocarbon group, an acyl group, or an acid-labile group. When R 54 , R 55 and R 56 are a monovalent hydrocarbon group or a fluorinated monovalent hydrocarbon group, a part of their carbon atoms may also be substituted with an ether group or a carbonyl group. R 57It is a linear, branched or cyclic hydrocarbon group or fluorinated hydrocarbon group with a valence of (v + 1) and 1 to 20 carbon atoms. v is an integer from 1 to 3.

[0310] R 51 and R 52 Examples of the monovalent hydrocarbon group with 1 to 10 carbon atoms represented by include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, adamantyl, norbornyl, etc. Among them, a linear, branched or cyclic monovalent hydrocarbon group with 1 to 6 carbon atoms is preferred.

[0311] R 53 Specific examples of the divalent hydrocarbon group with 1 to 5 carbon atoms represented by include: methylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, etc.

[0312] R 54 、R 55 and R 56 Examples of the monovalent hydrocarbon group with 1 to 15 carbon atoms represented by, and include: alkyl groups, alkenyl groups, alkynyl groups, etc., and alkyl groups are preferred. In addition to the aforementioned ones, the aforementioned alkyl groups may also include n-undecyl, n-dodecyl, tridecyl, tetradecyl, pentadecyl, etc. Examples of the fluorinated monovalent hydrocarbon group with 1 to 15 carbon atoms include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned monovalent hydrocarbon group are replaced by fluorine atoms. As described above, some of their carbon atoms may also be replaced by ether groups or carbonyl groups.

[0313] R 54 、R 55 and R 56 When it is an acid-labile group, specific examples thereof include: the groups represented by the aforementioned formulas (L1) to (L9), tertiary alkyl groups with 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, oxoalkyl groups with 4 to 20 carbon atoms, etc.

[0314] R 57 Examples of the (v + 1)-valent hydrocarbon group or fluorinated hydrocarbon group with 1 to 20 carbon atoms represented by include groups formed by removing a necessary number of hydrogen atoms from the aforementioned monovalent hydrocarbon group or fluorinated monovalent hydrocarbon group, etc.

[0315] Examples of the repeating unit represented by formula (D-1) include those shown below, but are not limited thereto. In addition, in the following formula, R A is the same as the aforementioned one.

[0316] [Chemical formula 67]

[0317]

[0318] The repeating units represented by formula (D-2) are exemplified as follows, but are not limited thereto. In addition, in the following formula, R A is the same as described above.

[0319] [Chemical formula 68]

[0320]

[0321] The repeating units represented by formula (D-3) are exemplified as follows, but are not limited thereto. In addition, in the following formula, R A is the same as described above.

[0322] [Chemical formula 69]

[0323]

[0324] The Mw of the fluororesin of component (D) is preferably 1,000 to 100,000, more preferably 3,000 to 15,000. The Mw / Mn is preferably 1.0 to 2.0, more preferably 1.0 to 1.6.

[0325] When synthesizing the fluororesin of component (D), one method is, for example, to add a radical initiator to monomers having unsaturated bonds for obtaining the repeating units represented by formulas (D-1) to (D-3) and other repeating units as needed, and carry out heat polymerization in an organic solvent. Examples of the organic solvent used in the polymerization include toluene, benzene, THF, diethyl ether, dioxane, methyl ethyl ketone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc. Examples of the polymerization initiator include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide, etc. The reaction temperature is preferably 50 to 100 °C. The reaction time is preferably 4 to 24 hours. The acid-labile group can be directly used as introduced into the monomer, or can be protected or partially protected after polymerization. Also, in order to adjust the molecular weight, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol can be used to carry out the polymerization. At this time, the addition amount of the chain transfer agent relative to all the monomers to be polymerized is preferably an amount represented by a molar ratio of 0.01 to 10.

[0326] When the resist composition of the present invention contains the fluororesin of component (D), its content is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the base resin of component (A). If the content is within the above range, the contact angle between the resist film surface and water can be sufficiently improved, and defects caused by residual infiltrated water or the dissolution of the acid generator and quencher can be suppressed. In addition, the solubility of the resist film surface can be adjusted, and good size uniformity can be achieved.

[0327] [Other components]

[0328] The resist composition of the present invention may also contain an amine compound, a sulfonate or a carboxylate as a quencher as needed. In this specification, a quencher means a compound that can inhibit the diffusion rate when the acid generated from a photoacid generator diffuses in the resist film.

[0329] Among such quenchers, the amine compound may include primary, secondary or tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, and particularly, an amine compound having any one of a hydroxyl group, an ether group, an ester group, a lactone ring, a cyano group, a sulfonate group, etc. can be cited as a preferred example. Also, a compound in which a primary or secondary amine is protected in the form of a carbamate group as described in JP No. 3790649 can be cited. Such a protected amine compound is effective when there is an alkali-labile component in the resist composition.

[0330] The aforementioned sulfonate may include a compound represented by the following formula (Z1). Also, the aforementioned carboxylate may include a compound represented by the following formula (Z2).

[0331] [Chemical Formula 70]

[0332]

[0333] R 101 is a hydrogen atom, or a hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom, provided that the hydrogen atom bonded to the α-position carbon atom of the sulfo group is not substituted with a fluorine atom or a fluoroalkyl group. M + are each independently an onium cation, and the same ones as those exemplified above can be cited.

[0334] The aforementioned hydrocarbon group may be saturated or unsaturated, and may be any of linear, branched or cyclic. Specific examples thereof include: alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6Cyclic saturated hydrocarbon groups such as decyl, adamantyl, and adamantylmethyl; examples of alkenyl groups include vinyl, allyl, propenyl, butenyl, and hexenyl; unsaturated aliphatic cyclic hydrocarbon groups such as cyclohexenyl; aryl groups such as phenyl, naphthyl, alkylphenyl (2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-tert-butylphenyl, 4-n-butylphenyl, etc.), dialkylphenyl (2,4-dimethylphenyl, 2,4,6-triisopropylphenyl, etc.), alkylnaphthyl (methylnaphthyl, ethylnaphthyl, etc.), dialkylnaphthyl (dimethylnaphthyl, diethylnaphthyl, etc.); heteroaryl groups such as thienyl; aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl.

[0335] Furthermore, a part of the hydrogen atoms of these groups may also be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and a part of the carbon atoms of these groups may also be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, it may also contain hydroxyl groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate ester bonds, carbonate ester bonds, lactone rings, sultone rings, carboxylic anhydrides, haloalkyl groups, etc. Examples of hydrocarbon groups containing heteroatoms include: alkoxyphenyl groups such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and 3-tert-butoxyphenyl; alkoxynaphthyl groups such as methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl, and n-butoxynaphthyl; dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl; aryl-side oxyalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl.

[0336] R 102 is a hydrocarbon group having 1 to 40 carbon atoms that may also contain heteroatoms. The hydrocarbon group represented by R 102 may be exemplified by the same ones as those of the hydrocarbon group represented by R 101 represented. Furthermore, other specific examples may also include: fluoroalkyl groups such as trifluoromethyl, trifluoroethyl, 2,2,2-trifluoro-1-methyl-1-hydroxyethyl, and 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl; fluoroaryl groups such as pentafluorophenyl or 4-trifluoromethylphenyl.

[0337] The sulfonates represented by the formula (Z1) may be exemplified as shown below, but are not limited thereto.

[0338] [Chemical formula 71]

[0339]

[0340] [Chemical formula 72]

[0341]

[0342] Examples of the carboxylate represented by the formula (Z2) include, but are not limited to, those shown below.

[0343] [Chemical Formula 73]

[0344]

[0345] When the resist composition of the present invention contains the aforementioned quencher, its content is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, based on 100 parts by mass of the base resin of the component (A). Due to the incorporation of the quencher, the adjustment of the resist sensitivity becomes easy, and the diffusion rate of acid in the resist film can be suppressed and the resolution can be improved, the sensitivity change after exposure can be suppressed, or the substrate and environment dependence can be reduced, improving the exposure latitude, pattern profile, etc. Also, by adding these quenchers, the substrate adhesion can be improved. The aforementioned quenchers can be used alone or in combination of two or more.

[0346] [Surfactant]

[0347] The resist composition of the present invention may also contain a surfactant that is insoluble or hardly soluble in water and soluble in an alkali developer and / or a surfactant component that is insoluble or hardly soluble in water and an alkali developer. Such surfactants can be referred to the (S)-defined components described in JP-A-2010-215608 and JP-A-2011-16746.

[0348] Regarding the surfactant that is insoluble or hardly soluble in water and an alkali developer, among the surfactants described in the aforementioned publications, FC-4430 (manufactured by 3M), SURFLON (registered trademark) S-381 (manufactured by AGC SEIMI CHEMICAL Co., Ltd.), SURFYNOL (registered trademark) E1004 (manufactured by AIR PRODUCTS), KH-20, KH-30 (manufactured by Asahi Glass Co., Ltd.), and the oxetane ring-opening polymer represented by the following structural formula (surf-1) are preferable. They can be used alone or in combination of two or more.

[0349] [Chemical Formula 74]

[0350]

[0351] However, Rf, R, M, A, B, C, and N in the above formula are only applicable to that formula.

[0352] In the formula (surf-1), R is an aliphatic group having 2 to 5 carbon atoms and 2 to 4 valences. Specifically, in the case of a divalent group, examples include: ethylene, tetramethylene, propylene, 2,2-dimethyl-1,3-propanediyl, pentamethylene, etc. In the case of a trivalent or tetravalent group, examples include those shown below, etc.

[0353] [Chemical 75]

[0354]

[0355] In the formula, the broken line represents an atomic bond, which are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.

[0356] Among them, tetramethylene or 2,2-dimethyl-1,3-propanediyl is preferably used. Rf is trifluoromethyl or pentafluoroethyl, preferably trifluoromethyl. M is an integer from 0 to 3, N is an integer from 1 to 4, and the sum of M and N represents the valence of R, which is an integer from 2 to 4. A is 1, B is an integer from 2 to 25, and C is an integer from 0 to 10. B is preferably an integer from 4 to 20, and C is preferably 0 or 1. Also, the arrangement of each constituent unit of the foregoing structure is not limited, and they can be bonded in block or randomly. For the manufacture of the surfactant of the partially fluorinated oxetane ring-opening polymer system, see the specification of U.S. Patent No. 5650483, etc.

[0357] [Pattern Formation Method]

[0358] The present invention further provides a pattern formation method using the foregoing resist composition. When forming a pattern using the resist composition of the present invention, it can be implemented by known lithography techniques. Specifically, for example, the resist composition of the present invention is coated on a substrate for integrated circuit manufacturing (Si, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.), or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi 2 , SiO 2 , etc.) by a method such as spin coating, so that the film thickness becomes 0.05 to 2 μm, and then it is prebaked on a hot plate at preferably 60 to 150 °C for 1 to 10 minutes, more preferably 80 to 140 °C for 1 to 5 minutes, to form a resist film.

[0359] Then, a mask for forming a target pattern is placed over the foregoing resist film, and high-energy rays such as KrF excimer laser, ArF excimer laser, EUV with a wavelength of 3 to 15 nm, and EB are irradiated, so that the exposure dose is preferably 1 to 200 mJ / cm 2 , more preferably 10 to 100 mJ / cm 2 , or preferably 0.1 to 100 μC / cm 2 , more preferably 0.5 to 50 μC / cm 2Better. In addition to the usual exposure method, immersion exposure can also be carried out by inserting a liquid with a refractive index of 1.0 or more between the resist film and the projection lens. At this time, a water-insoluble protective film can also be used. Then, post-exposure baking (PEB) is preferably carried out on a hot plate at 60 to 150 °C for 1 to 5 minutes, more preferably at 80 to 140 °C for 1 to 3 minutes. Then, a developer containing an aqueous alkali solution such as tetramethylammonium hydroxide (TMAH) at preferably 0.1 to 5% by mass, more preferably 2 to 3% by mass, or an organic solvent developer such as butyl acetate is used, and development is preferably carried out for 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, by common methods such as dip method, puddle method, spray method, etc., thereby forming a target pattern on the substrate.

[0360] The aforementioned water-insoluble protective film is used to prevent the eluate from the resist film and improve the hydrophilicity of the film surface, and is roughly divided into two types. One is an organic solvent stripping type that needs to be stripped with an organic solvent that does not dissolve the resist film before alkali development, and the other is an alkali-soluble type that is soluble in the alkali developer and removes the protective film together when removing the soluble part of the resist film. The latter is particularly excellent as a material prepared by dissolving a water-insoluble and alkali-developer-soluble high molecular compound having a 1,1,1,3,3,3-hexafluoro-2-propanol residue in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixed solvent thereof. It can also be made into a material prepared by dissolving the aforementioned water-insoluble and alkali-developer-soluble surfactant in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixed solvent thereof.

[0361] Also, in terms of the means of the pattern formation method, post-soak with pure water can be carried out after the photoresist film is formed to perform extraction of an acid generator or the like from the film surface or rinsing of fine particles, or post-soak can be carried out to remove the water remaining on the film after exposure.

[0362] In addition, the developer for the pattern formation method of the present invention can be an aqueous alkali solution such as TMAH at preferably 0.1 to 5% by mass, more preferably 2 to 3% by mass, as described above, but an organic solvent can also be used. At this time, negative tone development in which the unexposed portion is developed / dissolved can be carried out.

[0363] In this organic solvent development, one or more selected from 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate, butenyl acetate, isoamyl acetate, phenyl acetate, propyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, amyl lactate, isoamyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, benzyl acetate, methyl phenylacetate, benzyl formate, phenethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, 2-phenylethyl acetate, etc. can be used as the developer.

[0364] Examples

[0365] Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to the following examples.

[0366] [1] Synthesis of photoacid generator (PAG)

[0367] [Example 1-1]

[0368] [Chemical formula 76]

[0369]

[0370] 100 g of ammonium salt 1, 68.7 g of cationic intermediate 1, 100 g of pure water and 400 g of dichloromethane were mixed and stirred and aged for 1 hour. After separating and extracting the organic layer, it was washed twice with a mixed solution of 5.7 g of cationic intermediate 1 and 100 g of pure water, then washed 5 times with 100 g of pure water, and then washed twice with 100 g of 20 wt% methanol aqueous solution. The obtained organic layer was concentrated, PGMEA was added and then concentrated again to prepare a 20 wt% PGMEA solution. The obtained PGMEA solution was stirred overnight at room temperature to precipitate solids, then 500 g of hexane was added and stirred for 2 hours. The obtained solid was separated by filtration, rinsed with 200 g of hexane, and finally dried under reduced pressure and heated at 50 °C to obtain 104.8 g of the target PAG1 (yield 88%). The obtained PAG1's 1 1H NMR is shown in Figure 1 , 19 19F NMR is shown in Figure 2 .

[0371] IR(D-ATR): ν = 3087, 3002, 2906, 2852, 1785, 1727, 1477, 1448, 1344, 1240, 1180, 1103, 1076, 1035, 1010, 997, 943, 750, 684, 642, 551, 522, 501 cm -1

[0372] [Example 1-2]

[0373] [Chemical Formula 77]

[0374]

[0375] 417 g of ammonium salt 2, 268 g of cationic intermediate 2, 1400 g of pure water and 2000 g of dichloromethane were mixed and stirred for 1 hour for aging. After separating and extracting the organic layer, the organic layer was washed 6 times with 600 g of pure water, and then washed 6 times with 600 g of 20 wt% methanol aqueous solution. 25 g of activated carbon was added to the obtained organic layer and stirred overnight at room temperature. After removing the activated carbon by filtration, the organic layer was washed once with 600 g of 1% hydrochloric acid, then washed twice with 600 g of pure water, then washed once with 600 g of 1% hydrochloric acid, and then washed three times with 600 g of pure water. Further washed once with 600 g of 0.04 eq. of ammonia water, then washed three times with 600 g of pure water, then washed once with 600 g of 0.5% hydrochloric acid, and then washed three times with 600 g of pure water. The organic layer was concentrated, PGMEA was added and then concentrated again to prepare a 50 wt% PGMEA solution. The concentrated solution was added dropwise to 3.5 L of diisopropyl ether to precipitate crystals. After stirring for 1 hour, it was filtered and washed with diisopropyl ether, and finally dried under reduced pressure and heated at 50 °C to obtain 535 g of the target PAG2 (yield 86%). The obtained PAG2's 1 1H NMR is shown in Figure 3 , 19 19F NMR is shown in Figure 4 .

[0376] IR(D-ATR): ν = 3089, 2907, 2853, 1785, 1729, 1476, 1449, 1344, 1237, 1180, 1104, 1076, 1035, 1010, 947, 761, 707, 681, 642, 585, 551, 525 cm -1

[0377] [Examples 1-3 to 1-9] Synthesis of other PAGs (PAG-3 to PAG-9)

[0378] The corresponding raw materials were used and PAG-3 to PAG-9 were synthesized by known organic synthesis methods.

[0379] [Chemical formula 78]

[0380]

[0381] [2] Synthesis of Polymer

[0382] The polymer used in the resist composition of the present invention was synthesized by the method shown below. In addition, the Mw of the obtained polymer was a polystyrene conversion value measured by GPC using THF or DMF as a solvent.

[0383] [Synthesis Example 1] Synthesis of Resist Polymer 1

[0384] [Chemical formula 79]

[0385]

[0386] Under a nitrogen atmosphere, p-hydroxystyrene (27.8 g), 1-methylcyclopentyl methacrylate (72.2 g), and dimethyl 2,2'-azobis(2-methylpropionate) (6.08 g) were dissolved in PGMEA (155 g) to prepare a solution. This solution was added dropwise to PGMEA (78 g) stirred at 80°C over 6 hours under a nitrogen atmosphere. After the addition was completed, the mixture was stirred at 80°C for 2 hours. After cooling to room temperature, the reaction solution was added dropwise to n-hexane (3000 g). The precipitated solid was filtered and dried in vacuo at 50°C for 20 hours to obtain resist polymer 1 in the form of a white powder solid. The yield was 85 g and the yield rate was 85%.

[0387] [Synthesis Examples 2 - 7] Synthesis of Resist Polymers 2 - 7

[0388] The monomer types and blending ratios were changed, and except for this, resist polymers 2 - 7 shown below were produced by the same method as in Synthesis Example 1.

[0389] [Chemical formula 80]

[0390]

[0391] [3] Preparation of Resist Composition

[0392] [Examples 2 - 1 to 2 - 40, Comparative Examples 1 - 1 to 1 - 38]

[0393] The onium salts (PAG-1 to PAG-9) of the present invention, comparative photoacid generators PAG-A to PAG-H, resist polymers 1 to 7, other photoacid generators PAG-X to PAG-Z, quenchers Q-1 to Q-4, and an alkali-soluble surfactant SF-1 were dissolved in a solvent containing 0.01% by mass of surfactant A (manufactured by OMNOVA Solutions Inc.) according to the compositions shown in Tables 1 and 2 below to prepare a solution, and the solution was filtered through a 0.2-μm Teflon (registered trademark) filter to obtain a resist composition.

[0394] [Table 1]

[0395]

[0396]

[0397] [Table 2]

[0398]

[0399]

[0400] In addition, in Tables 1 and 2, the solvent, comparative photoacid generators PAG-A to PAG-H, other photoacid generators PAG-X to PAG-Z, quenchers Q-1 to Q-4, and the alkali-soluble surfactant (fluoropolymer) SF-1 are as follows.

[0401] · PAG-A to PAG-H:

[0402] [Chemical Formula 81]

[0403]

[0404] · PAG-X to PAG-Z:

[0405] [Chemical Formula 82]

[0406]

[0407] · SF-1:

[0408] [Chemical Formula 83]

[0409]

[0410] · Q-1 to Q-4:

[0411] [Chemical Formula 84]

[0412]

[0413] · Solvent:

[0414] S-1: PGMEA (Propylene Glycol Monomethyl Ether Acetate)

[0415] S-2: GBL (γ-Butyrolactone)

[0416] · Surfactant A:

[0417] 3-Methyl-3-(2,2,2-trifluoroethoxymethyl)oxetane·tetrahydrofuran·2,2-dimethyl-1,3-propanediol copolymer (manufactured by OMNOVA Corporation)

[0418] [Chemical Formula 85]

[0419]

[0420] a: (b + b'): (c + c') = 1:4 to 7:0.01 to 1 (molar ratio)

[0421] Mw = 1,500

[0422] [4] Evaluation of the resist composition: EUV exposure patterning evaluation (hole pattern evaluation)

[0423] [Examples 3-1 to 3-40, Comparative Examples 2-1 to 2-38]

[0424] The resist compositions of the present invention (R-1 to R-40) and the comparative resist compositions (R-41 to R-78) were coated on a substrate with an organic antireflection film AL-412 having a film thickness of 20 nm manufactured by BRUWER SCIENCE using CLEAN TRACK Lithius ProZ manufactured by Tokyo Electron Limited, baked on a hot plate at 105°C for 60 seconds to form a 50-nm resist film. Using an EUV exposure machine NXE3300 manufactured by ASML, a 27.5-nm grid pattern was exposed with a pitch of 46 nm on the mask. After exposure, the PEB temperature suitable for each resist composition was applied, and while rotating the wafer, a 2.38% aqueous solution of tetramethylammonium was sprayed, and development was carried out for a total of 30 seconds. The alkali solution was washed away with water, and then the wafer was rotated at high speed to remove the water.

[0425] [Sensitivity evaluation]

[0426] The formed resist pattern was observed with a CD-SEM CG-5000 manufactured by Hitachi High-Technologies Corporation, and the exposure dose at which the hole diameter became 23 nm at a pitch of 46 nm was defined as the optimum exposure dose Eop (mJ / cm 2 ).

[0427] [MEF evaluation]

[0428] When the size on the mask is a pitch of 46 nm and the lattice pattern is 27.5 nm, and when observing with a CD-SEM, when observing the hole diameter near 23 nm, measure the CDs of the hole patterns when the size on the mask is a pitch of 46 nm and the lattice patterns are 26.0 nm, 26.5 nm, 27.0 nm, 27.5 nm, 28.0 nm, 28.5 nm, and 29.0 nm. Take the size on the mask and the slope of the observed CD as the MEF (Mask Error Enhancement Factor). An MEF of about 3.0 or less is defined as good MEF.

[0429] [Evaluation of Size Uniformity (CDU)]

[0430] For the hole pattern observed with the CD-SEM CG-5000 manufactured by Hitachi High-Technologies, measure the hole diameter at 32 points for each hole in one sample, measure 49 holes from one SEM image, calculate the 3-fold value (3σ) of the standard deviation (σ) obtained from the results, obtain 30 SEM images, and take the average value of the standard deviation as the CDU. The smaller the value of the CDU, the better the size uniformity. A CDU of about 3.2 or less is defined as good CDU.

[0431] [Table 3]

[0432]

[0433]

[0434] [Table 4]

[0435]

[0436]

[0437] From the results shown in Table 3, it can be seen that the resist composition (Example) of the present invention has good sensitivity and excellent MEF and CDU. On the other hand, as shown in Table 4, for the resist compositions (Comparative Examples) using known photoacid generators PAG-A to PAG-E (refer to Patent Documents 1 to 4), PAG-F and PAG-H without heteroatoms in W1, and PAG-G and PAG-H with heteroatoms in W2, their MEF and CDU are insufficient. Overall, it shows that the resist composition of the present invention is particularly suitable as a material for EUV lithography.

[0438] In addition, the present invention is not limited to the above embodiments. The above embodiments are illustrative, and those having a configuration substantially the same as the technical idea described in the claims of the present invention and exhibiting the same effects are intended to be included within the technical scope of the present invention.

Claims

1. A resist composition, characterized in that contain: (A) a resin containing repeating units having an acid-labile group and further containing at least one repeating unit having an aromatic substituent, wherein in the resin of component (A), one of the repeating units having an aromatic substituent is a repeating unit represented by the following formula (A-1), and the repeating units having an acid-labile group do not include a repeating unit represented by the following formula (a3'); (B) a photoacid generator, wherein the photoacid generator (B) is a photoacid generator represented by the general formula (B-1), and optionally at least one other photoacid generator selected from the group consisting of formula (B-2), formula (B-3), and formula (B-4); (C) solvent; and (D) component is a resin different from the resin of (A) component and is a fluorine-containing resin having at least one repeating unit selected from the group consisting of the following formulae (D-1), (D-2) and (D-3); In the formula, R A Represents a hydrogen atom or a methyl group; R 61 Represents a hydrogen atom; R 62 represents a linear, branched or cyclic hydrocarbon group having 1 to 8 carbon atoms which may be intercalated with a heteroatom; t is an integer of 1 to 3, u is an integer satisfying u≤5+2s-t; s is 0 or 1; L1 represents a single bond, or any one of -C(=O)O- and -C(=O)NH-; In the formula, W1 represents a cyclic divalent hydrocarbon group containing heteroatoms and having 4 to 12 carbon atoms; W2 represents a cyclic monovalent hydrocarbon group containing no heteroatoms and having 4 to 14 carbon atoms; Rf is a divalent organic group represented 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, a fluorine atom or a trifluoromethyl group; * represents an atomic bond with a carbonyloxy group; m represents 0 to 4, and n represents an integer from 0 to 1; M + represents an onium cation; Among them, R 1 represents a hydrogen atom or a methyl group; In formula (B-2), A 1 is a hydrogen atom or a trifluoromethyl group; R 21 is a linear, branched or cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms which may contain an oxygen atom, or a nitrogen-containing heterocyclic group, or a group represented by the following formula (i); M + is an onium cation; In formula (i), R 31 and R 32 are each independently a hydrogen atom, or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, 31 and R 32 They can also bond to each other and to the nitrogen atoms to which they are bonded to form a ring; R 33 It is a linear, branched or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom; In formula (B-3), A 2 is a hydrogen atom or a trifluoromethyl group; R 22 , R 23 and R 24 Each of them is independently a hydrogen atom, or a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom; p and q are each independently an integer of 0 to 5; r is an integer of 0 to 4; L is a single bond, an ether group, or a linear, branched, or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom; In formula (B-4), A 3 and A 4 are independently a hydrogen atom or a trifluoromethyl group, and are not both hydrogen atoms; R 25 is a linear, branched or cyclic monovalent hydrocarbon group having 1 to 35 carbon atoms which may contain an oxygen atom, or a nitrogen-containing heterocyclic group, or a group represented by the above formula (i); M + represents an onium cation; Among them, M + The onium cation represented by is at least one selected from the following: In the formula, R A are independently a hydrogen atom or a methyl group; R 51 and R 52 Each of R is independently a hydrogen atom, or a linear, branched or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms; 53 is a single bond, or a linear or branched divalent hydrocarbon group having 1 to 5 carbon atoms; R 54 , R 55 and R 56 R are each independently a hydrogen atom, or a linear, branched or cyclic monovalent hydrocarbon group having 1 to 15 carbon atoms, a fluorinated monovalent hydrocarbon group or an acyl group, or an acid-labile group; 54 , R 55 and R 56 When it is a monovalent hydrocarbon group or a fluorinated monovalent hydrocarbon group, part of their carbon atoms may be substituted by an ether group or a carbonyl group; R 57 It is a linear, branched or cyclic hydrocarbon group or a fluorinated hydrocarbon group having a valence of (v+1) and a carbon number of 1 to 20; v is an integer of 1 to 3.

2. The resist composition according to claim 1, wherein W1 in the general formula (B-1) is a cyclic divalent hydrocarbon group having 6 to 12 carbon atoms and containing a lactone ring structure.

3. The resist composition according to claim 1 or 2, wherein W2 in the general formula (B-1) is a polycyclic monovalent hydrocarbon group having 7 to 14 carbon atoms and containing no hetero atom.

4. The resist composition according to claim 1 or 2, wherein The Rf group in the general formula (B-1) is selected from the groups represented by the following formulae (Rf-1) to (Rf-6); * represents an atomic bond to the carbonyloxy group.

5. The resist composition according to claim 1 or 2, wherein In the resin of the component (A), one of the repeating units having an aromatic substituent is a repeating unit represented by the following general formulae (A-2) to (A-4); In the formula, R A are independently a hydrogen atom or a methyl group, R 201 is a single bond, phenylene, -OR 210 -, or -C(=O)-Z 2 -R 210 -;Z 2 is an oxygen atom or NH, R 210 is a linear, branched or cyclic alkylene, alkenylene or phenylene group having 1 to 6 carbon atoms, and may also contain a carbonyl group (-CO-), an ester group (-COO-), an ether group (-O-) or a hydroxyl group; L2 represents a single bond, or -Z 3 -C(=O)-O-,Z 3 represents a linear, branched or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms which may be substituted by a heteroatom; Z 1 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, -OR 211 -, or -C(=O)-Z 4 -R 211 -;Z 4 is an oxygen atom or NH, R 211 M is a linear, branched or cyclic alkylene, alkenylene or phenylene group having 1 to 6 carbon atoms, and may also contain a carbonyl group, an ester group, an ether group or a hydroxyl group; - Represents a non-nucleophilic counter ion; R 202 , R 203 , R 204 , R 205 , R 206 , R 207 , R 208 , R 209 Each independently represents a linear, branched or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a hetero atom or may be intercalated with a hetero atom; and R 202 and R 203 They may also be bonded to each other and to form a ring together with the sulfur atom in the formula, or R 204 , R 205 and R 206 Any two or more of, or R 207 , R 208 and R 209 Any two or more of them may be bonded to each other and form a ring together with the sulfur atom in the formula; however, the repeating units represented by the general formulae (A-2) to (A-4) have one or more aromatic substituents.

6. A pattern forming method, characterized by comprising the following steps: The resist composition according to any one of claims 1 to 5 is applied on a substrate and subjected to a heat treatment to form a resist film, exposing the resist film to high energy radiation, and The exposed resist film is developed using a developer.

7. The pattern forming method according to claim 6, wherein: The high-energy radiation is ArF excimer laser light having a wavelength of 193 nm or KrF excimer laser light having a wavelength of 248 nm.

8. The pattern forming method according to claim 6 or 7, wherein: This exposure is an immersion exposure performed by inserting a liquid having a refractive index of 1.0 or more between the resist film and the projection lens.

9. The pattern forming method according to claim 8, further comprising forming a protective film on the resist film, and inserting the liquid between the protective film and a projection lens to perform immersion exposure.

10. The pattern forming method according to claim 6, wherein: The high-energy rays are electron beams or extreme ultraviolet rays with a wavelength of 3 to 15 nm.

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