Resist composition and pattern forming method

Abstract

The invention relates to a resist composition and a pattern forming method. The present invention addresses the problem of providing: a resist composition which has high contrast and improved limit resolution in lithography using high-energy rays, while having excellent sensitivity and LWR; and a method for forming a pattern using the resist composition. The resist composition includes (A) a base polymer including a polymer including a repeating unit having an acid-labile group and a repeating unit having a carboxyl group, (B) an organic solvent, and (C) a superatomic iodine compound represented by formula (1). # imgabs0 #

Description

Technical Field

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

[0002] With the increasing integration and speed of LSIs, the miniaturization of pattern patterns is progressing rapidly. With the increasing popularity of 5G high-speed communications and artificial intelligence (AI), high-performance devices are needed to handle them. As the most advanced miniaturization technology, mass production of 5nm node devices using extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm is underway. Furthermore, the use of EUV lithography is also being explored for devices at the next-generation 3nm node and the next-generation 2nm node.

[0003] As miniaturization progresses, image blurring caused by acid diffusion has become a problem. To ensure resolution in fine patterns with dimensions below 45 nm, it has been proposed that controlling acid diffusion is important, in addition to improving dissolution contrast, as has been previously suggested (Non-Patent Document 1). However, since chemically amplified resist compositions improve sensitivity and contrast through acid diffusion, lowering the temperature or shortening the post-exposure heat treatment (PEB) time to limit acid diffusion significantly reduces sensitivity and contrast.

[0004] To address this issue, adding an acid generator that generates an acid with a large structural barrier is effective for controlling acid diffusion. Furthermore, some have proposed designs that further suppress acid diffusion by including repeating units derived from an onium salt with a polymerizable unsaturated bond in the polymer. In this case, the polymer also functions as an acid generator (polymer-bonded acid generator). Patent Document 1 proposes a polymer-bonded acid generator that generates a specific fluorosulfonic acid from a base polymer.

[0005] However, EUV lithography is required for fine patterning in 3nm and 2nm node devices. Acid diffusion control alone cannot guarantee sufficient resolution in such areas. For example, pattern defects such as bridging between patterns and bottom scum in line and space patterns are a problem, and insufficient contrast is a common cause.

[0006] As a method for increasing contrast, some have attempted to crosslink polymer chains using acid-degradable crosslinking groups. Crosslinking increases molecular weight, and the acid generated during exposure degrades the crosslinks in the exposed areas. Patent Document 2 discloses a crosslinked polymer obtained by reacting units containing carboxyl or hydroxyl groups with divinyl ether units.

[0007] On the other hand, a cross-linked polymer formed by cross-linking polymer chains has a very large molecular weight. If stored as a resist solution for a long time, the polymers aggregate, causing a problem of an increase in the number of defects.

[0008] Prior art literature

[0009] Patent Literature

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-133448

[0011] [Patent Document 2] Japanese Patent No. 5562651

[0012] [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-180928

[0013] [Patent Document 4] Japanese Patent Application Publication No. 2018-095853

[0014] Non-patent literature

[0015] [Non-Patent Document 1] SPIE Vol. 6520 65203L-1 (2007) Summary of the Invention

[0016] [Problems to be Solved by the Invention]

[0017] The present invention is made in view of the above situation, and its purpose is to provide a resist composition with high contrast and improved limiting resolution in lithography using high-energy rays, especially EB lithography and EUV lithography, and excellent sensitivity and line width roughness (LWR), and a pattern forming method using the resist composition.

[0018] [Methods for solving the problem]

[0019] To achieve the aforementioned objectives, the inventors of the present application have conducted repeated and in-depth studies, resulting in the discovery of a resist composition comprising: a base polymer comprising a polymer containing repeating units having acid-labile groups and repeating units having carboxyl groups, an organic solvent, and a predetermined hypervalent iodine compound. The resist composition improves contrast, resulting in excellent limiting resolution and being very effective for precise microfabrication, thereby completing the present invention.

[0020] That is, the present invention provides the following resist composition and pattern forming method.

[0021] 1. A resist composition comprising:

[0022] (A) a base polymer comprising a polymer containing a repeating unit having an acid-labile group and a repeating unit having a carboxyl group,

[0023] (B) organic solvents, and

[0024] (C) a hypervalent iodine compound represented by the following formula (1),

[0025] [Chemistry 1]

[0026]

[0027] Wherein, n is an integer from 0 to 5,

[0028] R 1 and R 2 are each independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom, and R 1 and R 2 They may also be bonded to each other and to the carbon atoms to which they are bonded and the atoms between the carbon atoms to form a ring.

[0029] R 3 It is a hydrocarbon group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom.

[0030] 2. The resist composition according to 1., wherein the repeating unit having an acid-labile group is represented by the following formula (a1) or (a2):

[0031] [Chemistry 2]

[0032]

[0033] Wherein, a is an integer from 0 to 4,

[0034] R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group,

[0035] X 1 is a single bond, phenylene, naphthylene or *-C(=O)-OX 11 -, X 11 is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, wherein the saturated alkylene group may contain at least one member selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, and a lactone ring.

[0036] X 2 is a single bond or *-C(=O)-O-,

[0037] * indicates atomic bonds to carbon atoms of the main chain,

[0038] R 11 is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom,

[0039] AL 1 and AL 2 Each is independently an acid-labile group.

[0040] 3. The resist composition according to 1. or 2., wherein the repeating unit having a carboxyl group is represented by the following formula (b):

[0041] [Chemistry 3]

[0042]

[0043] Where R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group,

[0044] Y 1 is a single bond, phenylene, naphthylene or *-C(=O)-OY 11 -, Y 11 It is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group. The saturated alkylene group may contain at least one selected from a hydroxyl group, an ether bond, an ester bond, and a lactone ring. * represents an atomic bond to a carbon atom of the main chain.

[0045] 4. The resist composition according to any one of 1. to 3., wherein the polymer further comprises at least one repeating unit selected from the group consisting of the repeating units represented by the following formulae (c1) and (c2),

[0046] [Chemistry 4]

[0047]

[0048] In the formula, b is 1 or 2, c is an integer from 0 to 4,

[0049] R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group,

[0050] Y 2 is a single bond or *-C(=O)-O-, * represents an atomic bond to a carbon atom of the main chain,

[0051] R 21 is a group having 1 to 20 carbon atoms containing at least one member selected from the group consisting of a hydroxyl group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-), R 22 It is a hydrocarbon group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom.

[0052] 5. The resist composition according to any one of 1. to 4., wherein the polymer further comprises a repeating unit having a photoacid generating group.

[0053] 6. The resist composition according to any one of 1. to 5., further comprising (D) a photoacid generator.

[0054] 7. The resist composition according to any one of 1. to 6., further comprising (E) a quencher.

[0055] 8. The resist composition according to any one of 1. to 7., further comprising (F) a surfactant.

[0056] 9. A pattern forming method comprising the following steps: forming a resist film on a substrate using the resist composition as described in any one of 1. to 8., exposing the resist film using a KrF excimer laser, an ArF excimer laser, an electron beam or extreme ultraviolet light, and developing the exposed resist film using a developer.

[0057] [Effects of the Invention]

[0058] The resist composition of the present invention has high contrast, so the LWR is small and a high-resolution pattern profile can be constructed. DETAILED DESCRIPTION

[0059] [Resist composition]

[0060] The resist composition of the present invention comprises the following: (A) a base polymer comprising a polymer containing repeating units having an acid-labile group and repeating units having a carboxyl group, (B) an organic solvent, and (C) a predetermined hypervalent iodine compound.

[0061] [(A) Base polymer]

[0062] Component (A), i.e., the base polymer, is a polymer comprising a repeating unit having an acid-labile group. The unit having an acid-labile group is preferably a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2).

[0063] [Chemistry 5]

[0064]

[0065] In formulae (a1) and (a2), a is an integer of 0 to 4, preferably 0 or 1. A Each independently represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 is a single bond, phenylene, naphthylene or *-C(=O)-OX 11 -.X 11 It is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group. The saturated alkylene group may also contain at least one member selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, and a lactone ring. 2 Is a single bond or *-C(=O)-O-. * is an atomic bond to a carbon atom of the main chain. R 11is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom. 1 and AL 2 Each is independently an acid-labile group.

[0066] X 11 The saturated alkylene group represented by may be linear, branched or cyclic. Specific examples thereof include alkane diyl groups having 1 to 10 carbon atoms, such as methane diyl, ethane-1,1-diyl, ethane-1,2-diyl, 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 and decane-1,10-diyl; and cyclic saturated alkylene groups having 3 to 10 carbon atoms, such as cyclopentane diyl, cyclohexane diyl, norbornane diyl and adamantane diyl.

[0067] R 11 Specific examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. 11 The hydrocarbon group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and combinations thereof, with aryl groups being preferred. Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may also contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0068] Change X in formula (a1) 1 The structures formed by the following can be listed, but are not limited to these. A and AL 1 Same as above.

[0069] [Chemistry 6]

[0070]

[0071] [Chemistry 7]

[0072]

[0073] The polymer containing the repeating unit a1 will decompose under the action of acid to generate carboxyl groups and become alkali-soluble.

[0074] AL 1 and AL 2 The acid-labile group represented is not particularly limited, and for example, it is preferably a group represented by any one of the following formulae (L1) to (L4), a tertiary hydrocarbon group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trihydrocarbylsilyl group in which each hydrocarbon group is a hydrocarbon group having 1 to 6 carbon atoms, a hydrocarbon group having 4 to 20 carbon atoms containing a carbonyl group, an ether bond or an ester bond, etc.

[0075] [Chemistry 8]

[0076]

[0077] In the formula, the dotted lines represent atomic bonds.

[0078] In formula (L1), R L01 and R L02 is a hydrogen atom or a saturated hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. The saturated hydrocarbon group may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-octyl, and 2-ethylhexyl; and cyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, norbornyl, tricyclodecanyl, tetracyclododecyl, and adamantyl.

[0079] In formula (L1), R L03 It is a hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, which may contain heteroatoms. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic, but is preferably a saturated hydrocarbon group. In addition, part or all of the hydrogen atoms of the aforementioned saturated hydrocarbon group may be substituted by a hydroxyl group, a saturated hydrocarbon oxy group, an oxo group, an amino group, a saturated hydrocarbon amino group, etc., and part of the -CH2- of the aforementioned saturated hydrocarbon group may be substituted by a group containing heteroatoms such as oxygen atoms. The aforementioned saturated hydrocarbon group may be exemplified by the same as for R L01 and R L02 The saturated hydrocarbon represented by is the same as that described above. Examples of substituted saturated hydrocarbon groups include the following groups.

[0080] [Chemistry 9]

[0081]

[0082] In the formula, the dotted lines represent atomic bonds.

[0083] R L01 、RL02 and R L03 Any two of them may be bonded to each other and form a ring together with the carbon atom or carbon atom and oxygen atom to which they are bonded. L01 、R L02 and R L03 It is desirable that any two of them are each independently an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms.

[0084] In formula (L2), R L04 It is a tertiary hydrocarbon group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trialkylsilyl group in which each alkyl group is an alkyl group having 1 to 6 carbon atoms, a saturated hydrocarbon group having 4 to 20 carbon atoms containing a carbonyl group, an ether bond, or an ester bond, or a group represented by formula (L1). x is an integer from 0 to 6.

[0085] R L04 The tertiary hydrocarbon group represented by may be branched or cyclic, and specific examples thereof include tert-butyl, tert-amyl, 1,1-diethylpropyl, 2-cyclopentylpropane-2-yl, 2-cyclohexylpropane-2-yl, 2-(bicyclo[2.2.1]heptan-2-yl)propane-2-yl, 2-(adamantan-1-yl)propane-2-yl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl, 2-methyl-2-adamantyl, and 2-ethyl-2-adamantyl. Examples of the trialkylsilyl group include trimethylsilyl, triethylsilyl, and dimethyl-tert-butylsilyl. Examples of the saturated hydrocarbon group containing a carbonyl group, an ether bond, or an ester bond include 3-oxocyclohexyl, 4-methyl-2-oxotetrahydropyran-4-yl, and 5-methyl-2-oxotetrahydrofuran-5-yl.

[0086] In formula (L3), R L05It is an optionally substituted saturated hydrocarbon group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. The saturated hydrocarbon group which may be substituted may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, and n-hexyl; cyclic saturated hydrocarbon groups such as cyclopentyl and cyclohexyl; and groups in which some or all of the hydrogen atoms are substituted with a hydroxyl group, a saturated hydrocarbon oxy group having 1 to 8 carbon atoms, a carboxyl group, a saturated hydrocarbon carbonyl group having 1 to 8 carbon atoms, an oxo group, an amino group, a saturated hydrocarbon amino group having 1 to 8 carbon atoms, a cyano group, a mercapto group, a saturated hydrocarbon thio group having 1 to 8 carbon atoms, a sulfonic acid group, and the like. Examples of the aforementioned aryl groups which may be substituted include phenyl, methylphenyl, naphthyl, anthracenyl, phenanthrenyl, pyrenyl, and groups in which some or all of the hydrogen atoms of these groups are substituted with hydroxyl, saturated hydrocarbonoxy having 1 to 8 carbon atoms, carboxyl, saturated hydrocarbon carbonyl having 1 to 8 carbon atoms, oxo, amino, saturated hydrocarbonamino having 1 to 8 carbon atoms, cyano, mercapto, saturated hydrocarbonthio having 1 to 8 carbon atoms, sulfonic acid groups, and the like.

[0087] In formula (L3), y is 0 or 1, z is an integer from 0 to 3, and 2y+z=2 or 3.

[0088] In formula (L4), R L06 is a saturated hydrocarbon 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. Specific examples of the saturated hydrocarbon group which may be substituted and the aryl group which may be substituted are respectively L05 The same as those exemplified by the representation.

[0089] In formula (L4), R L07 ~R L16 Each is independently a hydrogen atom, or a hydrocarbon group having 1 to 15 carbon atoms which may be substituted. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic, preferably a saturated hydrocarbon group. Examples of the aforementioned hydrocarbon group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, and n-decyl; cyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, and cyclohexylbutyl; and groups in which a part or all of the hydrogen atoms are substituted by hydroxyl, saturated hydrocarbonoxy groups having 1 to 8 carbon atoms, carboxyl groups, saturated hydrocarbonoxycarbonyl groups having 1 to 8 carbon atoms, oxo groups, amino groups, saturated hydrocarbonamino groups having 1 to 8 carbon atoms, cyano groups, mercapto groups, saturated hydrocarbonthio groups having 1 to 8 carbon atoms, and sulfonic acid groups. With respect to R L07 ~R L16 For example, two selected from these may be bonded to each other and form a ring together with the carbon atoms to which they are bonded (e.g., R L07 With R L08 、R L07 With R L09 、RL07 With R L10 、R L08 With R L10 、R L09 With R L10 、R L11 With R L12 、R L13 With R L14 In this case, the group involved in the formation of the ring is a hydrocarbon group having 1 to 15 carbon atoms. Examples of the hydrocarbon group include those exemplified above for the hydrocarbon group excluding one hydrogen atom. L07 ~R L16 The carbon atoms bonded to adjacent carbon atoms are not separated by any groups, and double bonds can also be formed (for example, R L07 With R L09 、R L09 With R L15 、R L13 With R L15 、R L14 With R L15 wait).

[0090] Among the acid-labile groups represented by formula (L1), the linear or branched ones include the following groups, but are not limited to these.

[0091] [Chemistry 10]

[0092]

[0093] In the formula, the dotted lines represent atomic bonds.

[0094] Examples of the acid-labile group represented by formula (L1) that is cyclic include tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl, tetrahydropyran-2-yl, and 2-methyltetrahydropyran-2-yl.

[0095] Examples of the acid-labile group represented by formula (L2) include tert-butoxycarbonyl, tert-butoxycarbonylmethyl, tert-amyloxycarbonyl, tert-amyloxycarbonylmethyl, 1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl, 1-ethylcyclopentyloxycarbonyl, 1-ethylcyclopentyloxycarbonylmethyl, 1-ethyl-2-cyclopentenyloxycarbonyl, 1-ethyl-2-cyclopentenyloxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl, 2-tetrahydropyranyloxycarbonylmethyl, and 2-tetrahydrofuranyloxycarbonylmethyl.

[0096] The acid-labile group represented by formula (L3) includes 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl, 1-isopropylcyclopentyl, 1-n-butylcyclopentyl, 1-sec-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, etc.

[0097] The acid-labile group represented by the formula (L4) is particularly preferably a group represented by the following formulas (L4-1) to (L4-4).

[0098] [Chemistry 11]

[0099]

[0100] In formulas (L4-1) to (L4-4), the dotted lines represent the bonding positions and bonding directions. L41 Each independently represents a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic, with saturated hydrocarbon groups being preferred. Examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, and n-hexyl; and cyclic saturated hydrocarbon groups such as cyclopentyl and cyclohexyl.

[0101] The groups represented by formulae (L4-1) to (L4-4) may exist as stereoisomers (mirror image isomers or diastereomers), and formulae (L4-1) to (L4-4) represent all of these stereoisomers. When the acid-labile group is a group represented by formula (L4), multiple stereoisomers may also be included.

[0102] For example, formula (L4-3) typically represents one or a mixture of two selected from the groups represented by the following formulae (L4-3-1) and (L4-3-2).

[0103] [Chemistry 12]

[0104]

[0105] Where R L41 Same as above. The dotted lines indicate the bond positions and directions.

[0106] Furthermore, formula (L4-4) typically represents one or a mixture of two or more selected from the groups represented by the following formulae (L4-4-1) to (L4-4-4).

[0107] [Chemistry 13]

[0108]

[0109] Where R L41 Same as above. The dotted lines indicate the bond positions and directions.

[0110] Formulas (L4-1) to (L4-4), (L4-3-1), (L4-3-2), and (L4-4-1) to (L4-4-4) typically represent these enantiomeric isomers and mixtures of enantiomeric isomers.

[0111] Furthermore, the bonding direction of formulas (L4-1) to (L4-4), (L4-3-1), (L4-3-2), and (L4-4-1) to (L4-4-4) is each on the exo side relative to the bicyclo[2.2.1]heptane ring, which achieves high reactivity in the acid catalyst removal reaction (see Japanese Patent Application Laid-Open No. 2000-336121). In the production of monomers having a tertiary exo-saturated hydrocarbon group having a bicyclo[2.2.1]heptane skeleton as a substituent, a monomer substituted with an endo-alkyl group represented by the following formulas (L4-1-endo) to (L4-4-endo) may be included. To achieve good reactivity, the exo ratio is preferably 50 mol% or more, and more preferably 80 mol% or more.

[0112] [Chemistry 14]

[0113]

[0114] Where R L41 Same as above. The dotted lines indicate the bond positions and directions.

[0115] Examples of the acid-labile group represented by formula (L4) include the following groups, but are not limited thereto.

[0116] [Chemistry 15]

[0117]

[0118] In the formula, the dotted lines represent atomic bonds.

[0119] Again, AL 1 and AL 2 Among the acid-labile groups represented by R, tertiary hydrocarbon groups having 4 to 20 carbon atoms, trihydrocarbylsilyl groups in which each hydrocarbon group is a hydrocarbon group having 1 to 6 carbon atoms, and saturated hydrocarbon groups having 4 to 20 carbon atoms containing a carbonyl group, an ether bond, or an ester bond can be exemplified. L04 The same as those exemplified in the description of .

[0120] Specific examples of the repeating unit a1 include those shown below, but are not limited to these. A Same as above.

[0121] [Chemistry 16]

[0122]

[0123] [Chemistry 17]

[0124]

[0125] [Chemistry 18]

[0126]

[0127] [Chemistry 19]

[0128]

[0129] [Chemistry 20]

[0130]

[0131] And, these specific examples are X 1 For a single bond, X 1 When it is other than a single bond, it can also be combined with the same acid-labile group. 1 Specific examples of the case of other than a single bond are as described above.

[0132] The polymer containing repeating unit a2, like repeating unit a1, will decompose under the action of acid to generate hydroxyl groups and become alkali-soluble. Specific examples of repeating unit a2 include those shown below, but are not limited to these. A Same as above.

[0133] [Chemistry 21]

[0134]

[0135] [Chemistry 22]

[0136]

[0137] The aforementioned polymer is characterized by containing, in addition to the repeating unit having an acid-labile group, a repeating unit having a carboxyl group (hereinafter also referred to as repeating unit b). The repeating unit b is preferably represented by the following formula (b).

[0138] [Chemistry 23]

[0139]

[0140] In formula (b), R A Y is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 is a single bond, phenylene, naphthylene or *-C(=O)-OY 11-.Y 11 It is a saturated alkylene group, phenylene group or naphthylene group having 1 to 10 carbon atoms. The saturated alkylene group may also contain at least one selected from a hydroxyl group, an ether bond, an ester bond and a lactone ring. * represents an atomic bond to a carbon atom of the main chain. Y 1 The saturated alkylene group represented by the formula (a1) may be linear, branched or cyclic. Specific examples thereof include the following: 11 The specific examples of the saturated hydrocarbylene group represented are the same as those exemplified in the examples.

[0141] Specific examples of the repeating unit b include those shown below, but are not limited thereto. A Same as above.

[0142] [Chemistry 24]

[0143]

[0144] [Chemistry 25]

[0145]

[0146] The polymer preferably further contains at least one selected from the group consisting of a repeating unit represented by the following formula (c1) (hereinafter also referred to as repeating unit c1) and a repeating unit represented by the following formula (c2) (hereinafter also referred to as repeating unit c2).

[0147] [Chemistry 26]

[0148]

[0149] In formulae (c1) and (c2), b is 1 or 2. c is an integer of 0 to 4, preferably 0 or 1. A Each is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 2 It is a single bond or *-C(=O)-O-. * represents an atomic bond to a carbon atom of the main chain. 21 It is a group having 1 to 20 carbon atoms and containing at least one member selected from the group consisting of a hydroxyl group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). 22 It is a hydrocarbon group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom.

[0150] R 22 Specific examples of the halogen atom represented by include the following: 11 The specific examples of the halogen atoms represented by are the same as those given above. 22 The hydrocarbon group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. 11The specific examples of the hydrocarbon group represented are the same as those exemplified in FIG.

[0151] Specific examples of the repeating unit c1 include those shown below, but are not limited to these. In the following formula, R A Same as above.

[0152] [Chemistry 27]

[0153]

[0154] [Chemistry 28]

[0155]

[0156] [Chemistry 29]

[0157]

[0158] [Chemistry 30]

[0159]

[0160] [Chemistry 31]

[0161]

[0162] [Chemistry 32]

[0163]

[0164] [Chemistry 33]

[0165]

[0166] [Chemistry 34]

[0167]

[0168] [Chemistry 35]

[0169]

[0170] Specific examples of the repeating unit c2 include those shown below, but are not limited to these. A Same as above.

[0171] [Chemistry 36]

[0172]

[0173] [Chemistry 37]

[0174]

[0175] [Chemistry 38]

[0176]

[0177] [Chemistry 39]

[0178]

[0179] [Chemistry 40]

[0180]

[0181] The repeating units c1 and c2 preferably have a lactone ring as a polar group in ArF lithography, and preferably have a phenolic hydroxyl group in KrF lithography, EB lithography, and EUV lithography.

[0182] The aforementioned polymer preferably contains a repeating unit having a photoacid generating group. In this way, the diffusion of the generated acid can be strongly controlled, and the LWR and size uniformity (CDU) can be improved. Specific examples of such a repeating unit having a photoacid generating group include a repeating unit represented by the following formula (d1) (hereinafter, also referred to as repeating unit d1), a repeating unit represented by the following formula (d2) (hereinafter, also referred to as repeating unit d2), a repeating unit represented by the following formula (d3) (hereinafter, also referred to as repeating unit d3), a repeating unit represented by the following formula (d4) (hereinafter, also referred to as repeating unit d4), etc.

[0183] [Chemistry 41]

[0184]

[0185] In formulas (d1) to (d4), R A Each is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 is a single bond or a phenylene group. 2 It is **-C(=O)-OZ 21 -, **-C(=O)-NH-Z 21 -or**-OZ 21 -.Z 21 It is an aliphatic alkylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these groups, and may contain at least one selected from a carbonyl group, an ester bond, an ether bond, and a hydroxyl group. 3 Each is independently a single bond, phenylene, naphthylene or *-C(=O)-OZ 31 -.Z 31 Z is an aliphatic alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group. The aliphatic alkylene group may contain at least one member selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, and a lactone ring. 4 Is a single bond or ***-Z 41 -C(=O)-O-. Z 41It is a C1-20 alkylene group which may contain a heteroatom. 5 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, phenylene substituted with trifluoromethyl, *-C(=O)-OZ 51 -, *-C(=O)-N(H)-Z 51 -or*-OZ 51 -.Z 51 It is an aliphatic alkylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain at least one selected from a carbonyl group, an ester bond, an ether bond, and a hydroxyl group. * indicates an atomic bond to a carbon atom of the main chain. ** indicates an atomic bond to Z 1 *** indicates atomic bond with Z 3 atomic bonds.

[0186] Z 21 、Z 31 and Z 51 The aliphatic alkylene group represented by may be linear, branched, or cyclic. Specific examples thereof include alkane diyl groups such as methane-1,1-diyl, ethane-1,2-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-1,3-diyl, propane-2,2-diyl, butane-1,1-diyl, butane-1,2-diyl, butane-1,3-diyl, butane-2,3-diyl, butane-1,4-diyl, 1,1-dimethylethane-1,2-diyl, pentane-1,5-diyl, 2-methylbutane-1,2-diyl, and hexane-1,6-diyl; cycloalkane diyl groups such as cyclopropane diyl, cyclobutane diyl, cyclopentane diyl, and cyclohexane diyl; and groups obtained by combining these.

[0187] Z 41 The alkylene group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those shown below, but are not limited to these.

[0188] [Chemistry 42]

[0189]

[0190] In the formula, the dotted lines represent atomic bonds.

[0191] In formula (d1), R 31 and R 32 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 31 and R 32They may also be bonded to each other and form a ring together with the sulfur atom to which they are bonded. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and combinations thereof, preferably aryl groups. Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may also contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0192] Specific examples of the cation of the repeating unit d1 include those shown below, but are not limited to these. A Same as above.

[0193] [Chemistry 43]

[0194]

[0195] [Chemistry 44]

[0196]

[0197] [Chemistry 45]

[0198]

[0199] [Chemistry 46]

[0200]

[0201] [Chemistry 47]

[0202]

[0203] [Chemistry 48]

[0204]

[0205] [Chemistry 49]

[0206]

[0207] In formula (d1), M - It is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride and bromide; fluoroalkylsulfonate ions such as trifluoromethanesulfonate, 1,1,1-trifluoroethanesulfonate, and nonafluorobutanesulfonate; arylsulfonate ions such as toluenesulfonate, benzenesulfonate, 4-fluorobenzenesulfonate, and 1,2,3,4,5-pentafluorobenzenesulfonate; alkylsulfonate ions such as methanesulfonate and butanesulfonate; imide ions such as bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and bis(perfluorobutylsulfonyl)imide; and methide ions such as tris(trifluoromethylsulfonyl)methide and tris(perfluoroethylsulfonyl)methide.

[0208] Examples other than the aforementioned non-nucleophilic counterions include a sulfonic acid anion represented by the following formula (d1-1) in which the α-position is substituted with a fluorine atom and a sulfonic acid anion represented by the following formula (d1-2) in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group.

[0209] [Chemistry 50]

[0210]

[0211] In formula (d1-1), R 33 is a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, a hydrocarbon carbonyloxy group having 2 to 30 carbon atoms, or a hydrocarbon oxycarbonyl group having 2 to 30 carbon atoms. The hydrocarbon group may also contain a halogen atom, an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbon moiety of the aforementioned hydrocarbon group, hydrocarbon carbonyloxy group, and hydrocarbon oxycarbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the following: fa1 The hydrocarbon groups represented are the same as those exemplified above.

[0212] In formula (d1-2), R 34 R is a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a hydrocarbon carbonyl group having 2 to 30 carbon atoms. The hydrocarbon group and hydrocarbon carbonyl group may also contain a halogen atom, an ether bond, an ester bond, a carbonyl group, or a lactone ring. 35 is a hydrogen atom, a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. The hydrocarbon portion of the aforementioned hydrocarbon group and hydrocarbon carbonyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include the following: fa1 The hydrocarbon groups represented by R are the same as those exemplified above. 35 Preferably it is trifluoromethyl.

[0213] Specific examples of the sulfonic acid anion represented by formula (d1-1) or (d1-2) include those shown below, but are not limited to these. In the following formula, R 35 As mentioned above, Ac is acetyl.

[0214] [Chemistry 51]

[0215]

[0216] [Chemistry 52]

[0217]

[0218] [Chemistry 53]

[0219]

[0220] [Chemistry 54]

[0221]

[0222] [Chemistry 55]

[0223]

[0224] [Chemistry 56]

[0225]

[0226] [Chemistry 57]

[0227]

[0228] [Chemistry 58]

[0229]

[0230] [Chemistry 59]

[0231]

[0232] [Chemistry 60]

[0233]

[0234] [Chemistry 61]

[0235]

[0236] [Chemistry 62]

[0237]

[0238] [Chemistry 63]

[0239]

[0240] In formulas (d2) and (d3), L 1 It is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate bond, a carbonate bond, or a carbamate bond. Among these, from the viewpoint of synthesis, an ether bond, an ester bond, and a carbonyl group are preferred, and an ester bond and a carbonyl group are more preferred.

[0241] In formula (d2), Rf 1 and Rf 2 Each independently represents a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. 1 and Rf 2 In order to increase the acid strength of the generated acid, it is preferred that all of them are fluorine atoms. 3 and Rf 4 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. Among these, Rf 3 and Rf 4 Preferably, at least one of them is trifluoromethyl.

[0242] In formula (d3), Rf 5 and Rf 6 Each independently represents a hydrogen atom, a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. 5 and Rf 6 At the same time, it is a hydrogen atom. Among these, in order to improve the solvent solubility, Rf 5 and Rf 6 Preferably, at least one of them is trifluoromethyl.

[0243] In formulae (d2) and (d3), d is an integer of 0 to 3, preferably 1.

[0244] The anion of the repeating unit d2 may be exemplified by the following, but is not limited thereto. A Same as above.

[0245] [Chemistry 64]

[0246]

[0247] [Chemistry 65]

[0248]

[0249] [Chemistry 66]

[0250]

[0251] [Chemistry 67]

[0252]

[0253] [Chemistry 68]

[0254]

[0255] [Chemistry 69]

[0256]

[0257] The anions of the repeating unit d3 may be exemplified by the following, but are not limited thereto. A Same as above.

[0258] [Chemistry 70]

[0259]

[0260] [Chemistry 71]

[0261]

[0262] [Chemistry 72]

[0263]

[0264] [Chemistry 73]

[0265]

[0266] [Chemistry 74]

[0267]

[0268] [Chemistry 75]

[0269]

[0270] The anion of the repeating unit d4 may be specifically listed below, but is not limited thereto. A Same as above.

[0271] [Chemistry 76]

[0272]

[0273] In formulas (d2) to (d4), A + It is an onium cation. Examples of the onium cation include sulfonium cations, iodonium cations, and ammonium cations, with sulfonium cations and iodonium cations being preferred. Specific examples thereof are the same as those exemplified for the cations represented by formulas (6-1) to (6-3) described below.

[0274] Repeating units d1 to d4 function as a photoacid generator. When a polymer containing repeating units d1 to d4 (ie, a polymer-bonded photoacid generator) is used, the resist composition of the present invention may or may not contain the photoacid generator (D) described below.

[0275] The aforementioned polymer may further contain a repeating unit having a structure in which a hydroxyl group is protected by an acid-labile group (hereinafter also referred to as repeating unit e). The repeating unit e is not particularly limited as long as it has a structure in which one or more hydroxyl groups are protected and the protecting group decomposes upon the action of an acid to generate a hydroxyl group. However, the repeating unit e represented by the following formula (e1) is preferred.

[0276] [Chemistry 77]

[0277]

[0278] In formula (e1), R A Same as above. e is an integer from 1 to 4. 41 It is a hydrocarbon group having a valence of (e+1) and a carbon number of 1 to 30, which may contain a heteroatom. 42 It is an acid-labile group.

[0279] In formula (e1), R 42 The acid-labile group represented by R may be any one that is deprotected by the action of an acid to generate a hydroxyl group. 42 The structure of is not particularly limited, and is preferably an acetal structure, a ketal structure, an alkoxycarbonyl group, an alkoxymethyl group represented by the following formula (e2), and particularly preferably an alkoxymethyl group represented by the following formula (e2).

[0280] [Chemistry 78]

[0281]

[0282] In the formula, * represents an atomic bond. 43 It is a hydrocarbon group having 1 to 15 carbon atoms.

[0283] R 42 Specific examples of the acid-labile group represented by the formula (e2), the alkoxymethyl group represented by the formula (e2), and the repeating unit e include the same ones as exemplified in the description of the repeating unit d described in JP-A-2020-111564.

[0284] The polymer may further include a repeating unit f derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or a derivative thereof. Examples of monomers providing the repeating unit f include, but are not limited to, the following.

[0285] [Chemistry 79]

[0286]

[0287] The aforementioned polymer may further contain repeating unit g derived from indene, vinylpyridine or vinylcarbazole.

[0288] In the aforementioned polymer, the content ratios of repeating units a1, a2, b, c1, c2, d1 to d4, e, f and g are preferably 0 < a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0 ≤ b ≤ 0.5, 0 ≤ c1 ≤ 0.6, 0 ≤ c2 ≤ 0.6, 0 ≤ d1 ≤ 0.4, 0 ≤ d2 ≤ 0.4, 0 ≤ d3 ≤ 0.4, 0 ≤ d4 ≤ 0.4, 0 ≤ e ≤ 0.4, 0 ≤ f ≤ 0.3 and 0 ≤ g ≤ 0.3, more preferably 0 < a1 ≤ 0.7, 0 ≤ a2 ≤ 0.7, 0 ≤ b ≤ 0.3, 0 ≤ c1 ≤ 0.5, 0 ≤ c2 ≤ 0.5, 0 ≤ d1 ≤ 0.3, 0 ≤ d2 ≤ 0.3, 0 ≤ d3 ≤ 0.3, 0 ≤ d'4 ≤ 0.3, 0 ≤ e ≤ 0.3, 0 ≤ f ≤ 0.3 and 0 ≤ g ≤ 0.3. However, a1 + a2 + b + c1 + c2 + d1 + d2 + d3 + d4 + e + f + g ≤ 1.

[0289] The weight-average molecular weight (Mw) of the aforementioned polymer is preferably 1,000 to 500,000, more preferably 3,000 to 100,000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no concern about a decrease in resolution caused by an inability to ensure a difference in dissolution rate before and after exposure. Also, in the present invention, Mw is a polystyrene conversion measurement value obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent.

[0290] Moreover, as the pattern rule becomes finer, the influence of Mw / Mn on the molecular weight distribution (Mw / Mn) of the aforementioned polymer tends to become larger. Therefore, in order to obtain a resist composition suitable for use with a fine pattern size, a narrow dispersion with Mw / Mn of 1.0 to 2.0 is preferred. If it is within the above range, there are few low molecular weight and high molecular weight polymers, and after exposure, there is no concern about observing foreign substances on the pattern or deterioration of the pattern shape.

[0291] Examples of the method for synthesizing the aforementioned polymer include a method in which a radical polymerization initiator is added and heated in an organic solvent to polymerize the monomers that provide the repeating units.

[0292] Examples of organic solvents used in the polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% relative to the total amount of monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the perspective of production efficiency.

[0293] The polymerization initiator can be added to the monomer solution and supplied to the reactor, or the initiator solution can be prepared separately from the monomer solution and supplied to the reactor independently. Since there is a possibility that the polymerization reaction will proceed and ultra-high molecular weight bodies will be generated due to the free radicals generated by the initiator during the standby time, it is better to prepare the monomer solution and the initiator solution independently and add them dropwise from the perspective of quality management. The acid-labile group can be directly introduced into the monomer, or it can be protected or partially protected after polymerization. In addition, in order to adjust the molecular weight, a well-known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol can be used in combination. In this case, the amount of these chain transfer agents added is preferably 0.01 to 20 mol% relative to the total amount of the monomers to be polymerized.

[0294] In the case of monomers containing hydroxyl groups, the hydroxyl groups can be replaced with acetal groups such as ethoxyethoxy groups that are easily deprotected by acid during polymerization, and then deprotected by weak acid and water after polymerization. Alternatively, the hydroxyl groups can be replaced with acetyl groups, formyl groups, pivaloyl groups, etc., and then hydrolyzed with an alkali after polymerization.

[0295] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene and other monomers may be heated and polymerized with a free radical polymerization initiator in an organic solvent. Alternatively, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to form polyhydroxystyrene or hydroxyvinylnaphthalene.

[0296] The base used in the alkaline hydrolysis may be aqueous ammonia, triethylamine, etc. The reaction temperature is preferably -20 to 100°C, more preferably 0 to 60°C, and the reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0297] Furthermore, the amount of each monomer in the monomer solution may be appropriately set so as to achieve a preferred content ratio of the repeating unit, for example.

[0298] The polymer obtained by the aforementioned production method can be processed as the final product using a reaction solution obtained by the polymerization reaction. The polymer solution can be added to a poor solvent and subjected to a purification step such as reprecipitation to obtain a powder, and then processed as the final product. From the perspective of operating efficiency and quality stabilization, it is preferred to process as the final product a polymer solution obtained by dissolving the powder obtained through the purification step in a solvent.

[0299] Specific examples of the solvent used at this time include ketones such as cyclohexanone and methyl-2-n-pentanone described in paragraphs

[0144] to

[0145] of Japanese Patent Application Laid-Open No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, Ethers such as 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 monotert-butyl ether acetate; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling point alcohol solvents such as diethylene glycol, propylene glycol, glycerol, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0300] The concentration of the polymer in the polymer solution is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass.

[0301] The reaction solution and polymer solution are preferably filtered. Filtering can remove foreign matter and gel that may cause defects, which is effective in stabilizing quality.

[0302] The material of the filter used in the aforementioned filtration may be fluorocarbon, cellulose, nylon, polyester, hydrocarbon, etc. For the filtration step of the resist composition, a filter formed of a fluorocarbon called Teflon (registered trademark), a hydrocarbon such as polyethylene, polypropylene, or nylon is preferred. The pore size of the filter can be appropriately selected in accordance with the target cleanliness, preferably less than 100 nm, more preferably less than 20 nm. In addition, these filters can be used alone or in combination. The filtration method may be to pass the solution only once, or it is more preferred to perform multiple filtrations to circulate the solution. The filtration step can be performed in any order and number of times in the manufacturing step of the polymer. It is preferred to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0303] The base polymer (A) may be used alone or in combination of two or more polymers having different composition ratios, Mw and / or Mw / Mn. Furthermore, the base polymer (A) may include, in addition to the aforementioned polymers, a hydrogenated ring-opening metathesis polymer, for which the polymer described in Japanese Patent Application Laid-Opening No. 2003-066612 may be used.

[0304] The (A) base polymer of the present invention, especially in the narrow pitch pattern formation using EUV lithography, preferably contains repeating units having photoacid generating groups. More preferably, the anionic skeleton that generates acid is bonded to the polymer. In this case, the diffusion of the acid is reduced to a limit. In addition, in the (A) base polymer of the present invention, the repeating units having acid-labile groups contain aromatic rings, and more preferably, the units containing phenolic hydroxyl groups represented by formula (c2). By being composed of aromatic groups, etching resistance will be improved, and the efficiency of secondary electron generation after receiving EUV light will also be improved.

[0305] [(B) Organic solvent]

[0306] The resist composition of the present invention contains an organic solvent as component (B). The organic solvent is not particularly limited as long as it can dissolve component (A) and the components described below. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentanone, and 2-heptanone described in paragraphs

[0144] to

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and DAA; ethers such as PGME, 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, methyl 2-hydroxyisobutyrate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate; and lactones such as GBL.

[0307] In the resist composition of the present invention, the content of the organic solvent (B) is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, relative to 80 parts by mass of the base polymer (A). The organic solvent (B) may be used alone or in combination of two or more.

[0308] [(C) Hypervalent iodine compounds]

[0309] The resist composition of the present invention further contains a hypervalent iodine compound represented by the following formula (1) as the component (C).

[0310] [Chemistry 80]

[0311]

[0312] In formula (1), n ​​is an integer of 0 to 5.

[0313] In formula (1), R 1 and R 2 are each independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom. 1 and R 2 They may also be bonded to each other and form a ring together with the carbon atoms to which they are bonded and the atoms between the carbon atoms. Specific examples of the aforementioned halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, and the like. The aforementioned hydrocarbon groups having 1 to 10 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.0 2,6 ]Cyclic saturated hydrocarbon groups having 3 to 10 carbon atoms, such as decyl and adamantyl; alkenyl groups, such as vinyl and allyl; aryl groups, such as phenyl and naphthyl, having 6 to 10 carbon atoms; groups obtained by combining these, etc. In addition, part or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and part of the -CH2- of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, resulting in the inclusion of hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), etc. R 1 and R 2 , preferably a hydrocarbon group having 1 to 4 carbon atoms.

[0314] In formula (1), R 3 is a halogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. When n is 2 to 5, each R 3 They may be the same as or different from each other. Specific examples of the aforementioned halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, and the like. The aforementioned hydrocarbon groups having 1 to 40 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.02,6 ] cyclic saturated hydrocarbon groups having 3 to 40 carbon atoms, such as decyl, adamantyl, and adamantylmethyl; and aryl groups having 6 to 40 carbon atoms, such as phenyl, naphthyl, and anthracenyl. Furthermore, some or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- groups of the aforementioned hydrocarbon groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. Consequently, the hydrocarbon groups may include hydroxyl groups, cyano groups, halogen atoms, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonate bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, and carboxylic anhydride (-C(=O)-OC(=O)-).

[0315] Specific examples of the hypervalent iodine compound represented by formula (1) include those shown below, but are not limited to these.

[0316] [Chemistry 81]

[0317]

[0318] [Chemistry 82]

[0319]

[0320] [Chemistry 83]

[0321]

[0322] [Chemistry 84]

[0323]

[0324] [Chemistry 85]

[0325]

[0326] [Chemistry 86]

[0327]

[0328] The content of the hypervalent iodine compound represented by formula (1) is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass, of the total solid content in the resist composition. Within the aforementioned range, sufficient sensitivity and resolution can be achieved, and there is no concern about the generation of foreign matter or defects during film formation.

[0329] The resist composition of the present invention comprises (A) a polymer containing repeating units having an acid-labile group and repeating units having a carboxyl group, (B) an organic solvent, and (C) a hypervalent iodine compound represented by formula (1) as essential components. This composition enables the formation of high-contrast images even in fine pattern formation, resulting in improved limiting resolution and LWR. The reason for this is not clearly determined, but is speculated as follows, for example.

[0330] The resist composition of the present invention is a so-called chemically amplified resist composition that utilizes acid generated by a photoacid generator upon exposure to cleave acid-labile groups in a polymer to generate polar groups, thereby exhibiting a dissolution contrast between exposed and unexposed areas. It is believed that in addition to the reaction mechanism of this conventional chemically amplified resist composition, the present invention also involves another reaction. Specifically, it involves a reaction between carboxyl groups in the polymer and the hypervalent iodine compound represented by formula (1).

[0331] The hypervalent iodine compound represented by formula (1) is a tricoordinate iodine compound. The iodine-oxygen bond in the aforementioned hypervalent iodine compound is a relatively weak bond known as a three-center four-electron bond. It is believed that when a carboxyl group-containing compound is present externally, a ligand exchange reaction will proceed in an equilibrium state. Therefore, during the film formation stage, the resist composition of the present invention will be in a state where the hypervalent iodine compound partially bonds with the carboxyl groups in the polymer. In other words, it is presumed that the polymers will be cross-linked via the hypervalent iodine compound.

[0332] As mentioned above, it is believed that the iodine-oxygen bond of the hypervalent iodine compound is weak and is cleaved by exposure. Therefore, during film formation, the polymer crosslinked by the hypervalent iodine compound is cleaved by exposure, resulting in a significant decrease in molecular weight in the exposed area.

[0333] Based on the above speculation, it is believed that the resist composition of the present invention exhibits dissolution contrast due to two factors: polarity change and molecular weight change. Therefore, it can achieve higher contrast than conventional chemically amplified resist compositions and improve resolution.

[0334] Resist compositions containing hypervalent iodine compounds are described in Patent Document 3. However, Patent Document 3 only states that the resist composition improves line edge roughness and does not mention the essential requirement of carboxyl-containing units in the polymer employed. Therefore, it is believed that the resist composition described in Patent Document 3 is unlikely to improve resolution by increasing contrast.

[0335] Patent document 4 describes the concept of using a polymer for a resist prepared using a hypervalent iodine compound containing a polymerizable group. In this case, the hypervalent iodine compound of Patent document 4 will be in a form in which the polymer is cross-linked. However, in this case, the solubility in the developer after exposure is deteriorated due to the high cross-linking density, and residues caused by insoluble matter will be generated during development, thereby deteriorating the resolution and LWR. On the other hand, the resist composition of the present invention is partially cross-linked during film formation, and the exposed part is easily dissolved in the developer, which improves the resolution performance. The idea of ​​further improving the performance by partial cross-linking through a ligand exchange reaction during film formation cannot be obtained from Patent document 4. Therefore, the resist composition of the present invention can be said to be a novel proposal to solve this problem.

[0336] [(D) Photoacid generator]

[0337] The resist composition of the present invention may also contain a photoacid generator as component (D). The photoacid generator of component (D) is not particularly limited as long as it is a compound that generates an acid upon irradiation with high-energy radiation. Suitable photoacid generators include those represented by the following formula (2).

[0338] [Chemistry 87]

[0339]

[0340] In formula (2), R 101 、R 102 and R 103 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. 101 、R 102 and R 103 Any two of them may be bonded to each other and form a ring together with the sulfur atom to which they are bonded. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those described in formula (d1), 31 and R 32 The cation of the sulfonium salt represented by formula (2) may be the same as those exemplified for the sulfonium cation represented by formula (6-1) described later.

[0341] In formula (2), Xa - Examples of the non-nucleophilic counter anion include anions selected from the following formulae (2A) to (2D).

[0342] [Chemistry 88]

[0343]

[0344] In formula (2A), R fais a hydrocarbon group having 1 to 40 carbon atoms and which may contain a fluorine atom or a heteroatom. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the following: fa1 The hydrocarbon groups represented are the same as those exemplified above.

[0345] The anion represented by formula (2A) is preferably represented by the following formula (2A').

[0346] [Chemistry 89]

[0347]

[0348] In formula (2A'), R HF It is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group.

[0349] R fa1 It is a hydrocarbon group having 1 to 38 carbon atoms, which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, or a halogen atom, with an oxygen atom being more preferred. The hydrocarbon group is particularly preferably one having 6 to 30 carbon atoms, in order to achieve high resolution when forming a fine pattern.

[0350] R fa1 The hydrocarbon group having 1 to 38 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, pentadecyl, heptadecyl, and eicosyl; cyclic saturated hydrocarbon groups having 3 to 30 carbon atoms, such as cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, norbornylmethyl, tricyclodecanyl, tetracyclododecyl, tetracyclododecylmethyl, and dicyclohexylmethyl; unsaturated aliphatic hydrocarbon groups having 2 to 30 carbon atoms, such as allyl and 3-cyclohexenyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, 1-naphthyl, and 2-naphthyl; aralkyl groups having 7 to 38 carbon atoms, such as benzyl and diphenylmethyl; and combinations thereof.

[0351] Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may also contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. Examples of heteroatom-containing hydrocarbon groups include tetrahydrofuranyl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-oxopropyl, 4-oxo-1-adamantyl, 5-hydroxy-1-adamantyl, 5-tert-butylcarbonyloxy-1-adamantyl, 4-oxatricyclo[4.2.1.0 3,7 ]nonan-5-one-2-yl, 3-oxocyclohexyl, etc.

[0352] For details on the synthesis of sulfonium salts containing anions represented by formula (2A'), see Japanese Patent Application Laid-Open Nos. 2007-145797, 2008-106045, 2009-7327, and 2009-258695. Sulfonium salts described in Japanese Patent Application Laid-Open Nos. 2010-215608, 2012-41320, 2012-106986, and 2012-153644 are also applicable.

[0353] Specific examples of the anion represented by formula (2A) include the same ones as those exemplified as the specific examples of the sulfonic acid anion represented by formula (d1-1) or (d1-2).

[0354] In formula (2B), R fb1 and R fb2 Each independently represents a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the following: fa1 The hydrocarbon groups represented by R are the same as those exemplified above. fb1 and R fb2 Preferably, it is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 They can also bond to each other and to the groups to which they are bonded (-CF2-SO2-N - -SO2-CF2-) together to form a ring, at this time, R fb1 With R fb2 The groups formed by bonding with each other are preferably fluorinated ethylene groups or fluorinated propylene groups.

[0355] In formula (2C), R fc1 、R fc2 and R fc3 Each independently represents a fluorine atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the following: fa1 The hydrocarbon groups represented by R are the same as those exemplified above. fc1 、R fc2 and R fc3 Preferably, it is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 They can also be bonded to each other and to the groups to which they are bonded (-CF2-SO2-C - -SO2-CF2-) together to form a ring, at this time, R fc1 With R fc2 The groups formed by bonding with each other are preferably fluorinated ethylene groups or fluorinated propylene groups.

[0356] In formula (2D), R fd is a hydrocarbon group having 1 to 40 carbon atoms which may contain heteroatoms. The aforementioned hydrocarbon group may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include the following: fa1 The hydrocarbon groups represented are the same as those exemplified above.

[0357] For details on the synthesis of the sulfonium salt containing the anion represented by formula (2D), see JP-A-2010-215608 and JP-A-2014-133723.

[0358] Specific examples of the anion represented by formula (2D) include those shown below, but are not limited to these.

[0359] [Chemistry 90]

[0360]

[0361] [Chemistry 91]

[0362]

[0363] Examples of the non-nucleophilic counter anion include anions having an aromatic ring substituted with an iodine atom or a bromine atom. Examples of such anions include those represented by the following formula (2E).

[0364] [Chemistry 92]

[0365]

[0366] In formula (2E), x is an integer satisfying 1≤x≤3. y and z are integers satisfying 1≤y≤5, 0≤z≤3, and 1≤y+z≤5. y is preferably an integer satisfying 1≤y≤3, more preferably 2 or 3. z is preferably an integer satisfying 0≤z≤2.

[0367] In formula (2E), X BI is an iodine atom or a bromine atom. When x and / or y are 2 or more, they may be the same as or different from each other.

[0368] In formula (2E), L 11 It is a saturated alkylene group having 1 to 6 carbon atoms and which may contain a single bond, an ether bond, or an ester bond. The saturated alkylene group may be linear, branched, or cyclic.

[0369] In formula (2E), L 12 When x is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms; when x is 2 or 3, it is a (x+1)-valent linking group having 1 to 20 carbon atoms, and the linking group may also contain an oxygen atom, a sulfur atom or a nitrogen atom.

[0370] In formula (2E), R fe is a hydroxyl group, a carboxyl group, a fluorine atom, a chlorine atom, a bromine atom, or an amino group, or a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbonoxy group having 1 to 20 carbon atoms, a hydrocarboncarbonyl group having 2 to 20 carbon atoms, a hydrocarbonoxycarbonyl group having 2 to 20 carbon atoms, a hydrocarboncarbonyloxy group having 2 to 20 carbon atoms, or a hydrocarbonsulfonyloxy group having 1 to 20 carbon atoms, which may also contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, an amino group, or an ether bond, or -N(R feA )(R feB )、-N(R feC )-C(=O)-R feD or -N(R feC )-C(=O)-OR feD . R feA and R feB Each independently represents a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms. feC R is a hydrogen atom or a saturated hydrocarbon group having 1 to 6 carbon atoms, and may also include a halogen atom, a hydroxyl group, a saturated hydrocarbonoxy group having 1 to 6 carbon atoms, a saturated hydrocarboncarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarboncarbonyloxy group having 2 to 6 carbon atoms. feD It is an aliphatic hydrocarbon group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may also contain a halogen atom, a hydroxyl group, a saturated hydrocarbonoxy group having 1 to 6 carbon atoms, a saturated hydrocarboncarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarboncarbonyloxy group having 2 to 6 carbon atoms. The aforementioned aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. The aforementioned hydrocarbon group, hydrocarbonoxy group, hydrocarboncarbonyl group, hydrocarbonoxycarbonyl group, hydrocarboncarbonyloxy group, and hydrocarbonsulfonyloxy group may be linear, branched, or cyclic. When x and / or z are 2 or more, each R feThey may be the same or different from each other.

[0371] Among these, R fe Preferably, it is hydroxyl, -N(R feC )-C(=O)-R feD 、-N(R feC )-C(=O)-OR feD , fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group, etc.

[0372] In formula (2E), Rf 11 ~Rf 14 Each independently represents a hydrogen atom, a fluorine atom or a trifluoromethyl group, at least one of which is a fluorine atom or a trifluoromethyl group. 11 With Rf 12 They can also be combined to form a carbonyl group. In particular, Rf 13 and Rf 14 Preferably, they are all fluorine atoms.

[0373] Specific examples of anions represented by formula (2E) include those shown below, but are not limited to these. In the following formula, X BI Same as above.

[0374] [Chemistry 93]

[0375]

[0376] [Chemistry 94]

[0377]

[0378] [Chemistry 95]

[0379]

[0380] [Chemistry 96]

[0381]

[0382] [Chemistry 97]

[0383]

[0384] [Chemistry 98]

[0385]

[0386] [Chemistry 99]

[0387]

[0388] [Chemistry 100]

[0389]

[0390] [Chemistry 101]

[0391]

[0392] [Chemistry 102]

[0393]

[0394] [Chemistry 103]

[0395]

[0396] [Chemistry 104]

[0397]

[0398] [Chemistry 105]

[0399]

[0400] [Chemistry 106]

[0401]

[0402] [Chemistry 107]

[0403]

[0404] [Chemistry 108]

[0405]

[0406] [Chemistry 109]

[0407]

[0408] [Chemistry 110]

[0409]

[0410] [Chemistry 111]

[0411]

[0412] [Chemistry 112]

[0413]

[0414] [Chemistry 113]

[0415]

[0416] [Chemistry 114]

[0417]

[0418] [Chemistry 115]

[0419]

[0420] The aforementioned non-nucleophilic counter anion may also include a fluorobenzenesulfonic acid anion bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, anions having a mechanism of decomposition by acid as described in International Publication No. 2021 / 200056 and Japanese Patent Application Laid-Open No. 2021-070692, anions having a cyclic ether group as described in Japanese Patent Application Laid-Open No. 2018-180525 and Japanese Patent Application Laid-Open No. 2021-035935, and anions described in Japanese Patent Application Laid-Open No. 2018-092159.

[0421] The aforementioned non-nucleophilic counter anions may also include anions of fluorine-free, cyclopentane-containing benzenesulfonic acid derivatives described in Japanese Patent Application Laid-Open Nos. 2006-276759, 2015-117200, 2016-065016, and 2019-202974, and fluorine-free benzenesulfonic acid anions and alkylsulfonic acid anions bound to an aromatic group containing an iodine atom described in Japanese Patent No. 6645464.

[0422] The aforementioned non-nucleophilic counter anion may also include anions of disulfonic acids described in JP-A-2015-206932, anions of sulfonic acids on one side and different sulfonamides or sulfonimides on the other side as described in WO-2020 / 158366, and anions of sulfonic acids on one side and carboxylic acids on the other side as described in JP-A-2015-024989.

[0423] Furthermore, the photoacid generator of the component (D) is preferably represented by the following formula (3).

[0424] [Chemistry 116]

[0425]

[0426] In formula (3), R 201 and R 202 Each independently represents a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom. 203 is a C1-30 alkylene group which may contain a heteroatom. 201 、R 202 and R 203 Any two of them may be bonded to each other and form a ring together with the sulfur atom to which they are bonded.

[0427] R 201 and R202 The hydrocarbon group having 1 to 30 carbon atoms represented by may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbon groups having 3 to 30 carbon atoms, such as decyl and adamantyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, tert-butylnaphthyl and anthracenyl; groups derived from combinations thereof, etc. Furthermore, part or all of the hydrogen atoms of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH2- of the aforementioned hydrocarbon group may be substituted by a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, the hydrocarbon group may also contain a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like.

[0428] R 203The alkylene group having 1 to 30 carbon atoms represented by may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, 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, heptane-1,17-diyl, and heptadecane-1,18-diyl. -an alkanediyl group having 1 to 30 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; a cyclic saturated alkylene group having 3 to 30 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, norbornanediyl, and adamantanediyl; an arylene group having 6 to 30 carbon atoms, such as phenylene, methylphenylene, ethylphenylene, n-propylphenylene, isopropylphenylene, n-butylphenylene, isobutylphenylene, sec-butylphenylene, tert-butylphenylene, naphthylene, methylnaphthylene, ethylnaphthylene, n-propylnaphthylene, isopropylnaphthylene, n-butylnaphthylene, isobutylnaphthylene, sec-butylnaphthylene, and tert-butylnaphthylene; and groups derived from combinations thereof. Furthermore, some or all of the hydrogen atoms of the aforementioned alkylene group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms. A portion of the -CH2- of the aforementioned alkylene group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. Consequently, the alkylene group may include a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. The aforementioned heteroatom is preferably an oxygen atom.

[0429] In formula (3), L A is a single bond, an ether bond, or an alkylene group having 1 to 20 carbon atoms which may contain heteroatoms. The aforementioned alkylene group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include the following: 203 The same as those exemplified for the alkylene group represented are also given.

[0430] In formula (3), X a 、X b 、X c and X d Each independently represents a hydrogen atom, a fluorine atom or a trifluoromethyl group. a 、X b 、X c and X d At least one of them is a fluorine atom or a trifluoromethyl group.

[0431] The photoacid generator represented by formula (3) is preferably represented by the following formula (3').

[0432] [Chemistry 117]

[0433]

[0434] In formula (3'), L A Same as above. X e is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 、R 302 and R 303 Each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom. The aforementioned hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the following: fa1 The same as those exemplified for the hydrocarbon groups represented are given. x' and y' are each independently an integer of 0 to 5, and z' is an integer of 0 to 4.

[0435] Examples of the photo-acid generator represented by formula (3) include the same ones as exemplified for the photo-acid generator represented by formula (2) in JP-A-2017-026980.

[0436] Among the aforementioned photoacid generators, those containing anions represented by formula (2A') or (2D) are particularly preferred because they have low acid diffusion and excellent solubility in solvents. Furthermore, those represented by formula (3') are particularly preferred because they have extremely low acid diffusion.

[0437] When the resist composition of the present invention contains a (D) photoacid generator, its content is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, relative to 80 parts by mass of the (A) base polymer. If the amount of the photoacid generator of the component (D) added is within the aforementioned range, the resolution is good, and there is no concern about the generation of foreign matter after the development or peeling of the resist film, so it is ideal. The photoacid generator of the component (D) can be used alone or in combination of two or more. By virtue of the aforementioned base polymer containing any of the repeating units d1 to d4, and / or by virtue of containing the (D) photoacid generator, the resist composition of the present invention can exert the effect of a chemically amplified resist composition.

[0438] [(E) Quencher]

[0439] The chemically amplified resist composition of the present invention preferably includes a quencher (acid diffusion controller). The quencher herein is a material used to form a desired pattern by trapping the acid generated from the photoacid generator in the chemically amplified resist composition, thereby preventing diffusion toward unexposed areas. Examples of such quenchers include onium salts represented by the following formulas (4) or (5).

[0440] [Chemistry 118]

[0441]

[0442] In formula (4), R 401 It is a hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfonic acid group is substituted with a fluorine atom or a fluoroalkyl group.

[0443] R 401 The hydrocarbon group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbon groups having 3 to 40 carbon atoms, such as decyl and adamantyl; aryl groups having 6 to 40 carbon atoms, such as phenyl, naphthyl, and anthracenyl; and groups obtained by combining these. Furthermore, a part or all of the hydrogen atoms of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and a part of the -CH2- of the aforementioned hydrocarbon groups may be substituted by groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, the hydrocarbon groups may also contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydride (-C(=O)-OC(=O)-), haloalkyl groups, and the like.

[0444] In formula (5), R 402 is a hydrogen atom, or a hydrocarbon group having 1 to 40 carbon atoms which may contain a hetero atom. Specific examples of the aforementioned hydrocarbon group which may contain a hetero atom include, except R 401 In addition to the substituents exemplified in the specific examples of , fluorinated saturated hydrocarbon groups such as trifluoromethyl and trifluoroethyl, and fluorinated aryl groups such as pentafluorophenyl and 4-trifluoromethylphenyl can be mentioned. Specific examples of the anion of the onium salt represented by formula (4) include those shown below, but are not limited to these.

[0445] [Chemistry 119]

[0446]

[0447] [Chemistry 120]

[0448]

[0449] [Chemistry 121]

[0450]

[0451] Specific examples of the anion of the onium salt represented by formula (5) include those shown below, but are not limited to these.

[0452] [Chemistry 122]

[0453]

[0454] [Chemistry 123]

[0455]

[0456] [Chemistry 124]

[0457]

[0458] In formulas (3) and (4), Mq + The onium cation is preferably a sulfonium cation represented by the following formula (6-1), an iodonium cation represented by the following formula (6-2), or an ammonium cation represented by the following formula (6-3).

[0459] [Chemistry 125]

[0460]

[0461] In formulas (6-1) to (6-3), R 411 ~R 419 are each independently a hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. 411 With R 412 They can also be bonded to each other and to the sulfur atoms to which they are bonded to form a ring, R 416 With R 417 They may also be bonded to each other and form a ring together with the nitrogen atom to which they are bonded. The aforementioned hydrocarbon groups include the following: 401 The same as described in the description.

[0462] Specific examples of the sulfonium cation represented by formula (6-1) include those shown below, but are not limited to these.

[0463] [Chemistry 126]

[0464]

[0465] Specific examples of the iodonium cation represented by formula (6-2) include those shown below, but are not limited to these.

[0466] [Chemistry 127]

[0467]

[0468] Specific examples of the ammonium cation represented by formula (6-3) include those shown below, but are not limited to these.

[0469] [Chemistry 128]

[0470]

[0471] Specific examples of the onium salt represented by formula (4) or (5) include any combination of the aforementioned anions and cations. Furthermore, these onium salts can be easily prepared by ion exchange reactions using known organic chemical methods. For information on ion exchange reactions, see, for example, Japanese Patent Application Publication No. 2007-145797.

[0472] The onium salt represented by formula (4) or (5) functions as a quencher in the chemically amplified resist composition of the present invention. This is because each counter anion of the onium salt is a conjugate base of a weak acid. Here, a weak acid is one that exhibits an acidity that is insufficient to deprotect the acid-labile group of the unit containing the acid-labile group contained in the base polymer. When the onium salt represented by formula (4) or (5) is used in combination with an onium salt-type photoacid generator having a conjugate base of a strong acid such as a sulfonic acid fluorinated at the α-position as a counter anion, it functions as a quencher. Specifically, when an onium salt that generates a strong acid such as a sulfonic acid fluorinated at the α-position is mixed with an onium salt that generates a weak acid such as a sulfonic acid or a carboxylic acid that is not fluorinated, the strong acid generated by the photoacid generator upon irradiation with high-energy radiation collides with the unreacted onium salt having a weak acid anion, and the weak acid is released by salt exchange, generating an onium salt having a strong acid anion. In this process, since the strong acid and the catalyst can exchange for the lower weak acid, the acid will apparently lose its activity and the acid diffusion can be controlled.

[0473] Here, when the photoacid generator that generates a strong acid is an onium salt, as mentioned above, the strong acid generated by irradiation with high-energy radiation can exchange with the weak acid. However, it is believed that the weak acid generated by irradiation with high-energy radiation will collide with the unreacted onium salt that generates the strong acid, making salt exchange difficult. This is because the onium cation easily forms an ion pair with the anion of the stronger acid.

[0474] When the resist composition of the present invention contains the onium salt represented by formula (4) or (5) as the quencher (E), its content is preferably 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, relative to 80 parts by mass of the base polymer (A).

[0475] Component (E), i.e., the quencher, may also be a nitrogen-containing compound. Examples of such nitrogen compounds include the primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate bond. Furthermore, examples include compounds described in JP-A-3790649, and compounds in which the primary or secondary amine is protected by a carbamate group.

[0476] Alternatively, a sulfonium sulfonate salt with a nitrogen-containing substituent may be used as the aforementioned nitrogen-containing compound. Such a compound acts as a quencher in the unexposed area, while the exposed area loses its quenching ability due to neutralization with the acid it produces, thus acting as a so-called photodestructive base. The use of a photodestructive base can further enhance the contrast between the exposed and unexposed areas. For example, reference can be made to Japanese Patent Application Publication Nos. 2009-109595 and 2012-046501 for photodestructive bases.

[0477] When the resist composition of the present invention includes a nitrogen-containing compound as a quencher, its content is preferably 0.001 to 12 parts by mass, and more preferably 0.01 to 8 parts by mass, relative to 80 parts by mass of the base polymer (A). The nitrogen-containing compound may be used alone or in combination of two or more.

[0478] [(F) Surfactant]

[0479] The resist composition of the present invention may further include a surfactant as component (F). The surfactant (F) is preferably a surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer, or a surfactant that is insoluble or poorly soluble in water and an alkaline developer. Such surfactants can be described in Japanese Patent Application Laid-Open Nos. 2010-215608 and 2011-016746.

[0480] The surfactant that is insoluble or poorly soluble in water and an alkaline developer is preferably one of the surfactants described in the aforementioned publication, such as FC-4430 (manufactured by 3M Co., Ltd.), Surflon (registered trademark) S-381 (manufactured by AGC Seimichemical Co., Ltd.), OLFINE (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimichemical Co., Ltd.), and an oxetane ring-opening polymer represented by the following formula (surf-1).

[0481] [Chemistry 129]

[0482]

[0483] Here, R, Rf, A, B, C, m, and n are not limited to those described above and apply only to formula (surf-1). R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of such aliphatic groups include ethylene, 1,4-butylene, 1,2-propylene, 2,2-dimethyl-1,3-propylene, and 1,5-pentylene, for divalent groups. Examples of such aliphatic groups include the following for trivalent and tetravalent groups.

[0484] [Chemistry 130]

[0485]

[0486] In the formula, the dotted lines are atomic bonds, which are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.

[0487] Among these, 1,4-butylene group, 2,2-dimethyl-1,3-propylene group, and the like are preferred.

[0488] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer from 0 to 3, n is an integer from 1 to 4, the sum of n and m is the valence of R, and is an integer from 2 to 4. A is 1. B is an integer from 2 to 25, preferably from 4 to 20. C is an integer from 0 to 10, preferably 0 or 1. In addition, the arrangement of the constituent units in formula (surf-1) is not specified and may be bonded in blocks or randomly. For details on the production of surfactants based on partially fluorinated oxetane ring-opening polymers, see the specification of U.S. Patent No. 5,650,483.

[0489] Surfactants that are insoluble or poorly soluble in water but soluble in alkaline developers function by aligning with the surface of the resist film, thereby reducing water infiltration and leaching, when a resist protective film is not used during ArF immersion lithography. Therefore, they are useful for inhibiting the dissolution of water-soluble components from the resist film and reducing damage to the exposure apparatus. Furthermore, they are useful for solubilizing foreign matter that is less likely to cause defects during alkaline aqueous development after exposure or after a post-exposure bake (PEB). Such surfactants are polymeric surfactants, also known as hydrophobic resins, that are insoluble or poorly soluble in water but soluble in alkaline developers. Particularly preferred are those with high water repellency and improved water slip properties.

[0490] Specific examples of such polymeric surfactants include those containing at least one type of repeating unit selected from the group consisting of repeating units represented by any of the following formulae (7A) to (7E).

[0491] [Chemistry 131]

[0492]

[0493] In formulas (7A) to (7E), R B W is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 It is -CH2-, -CH2CH2-, -O- or 2 -H separated from each other. s1 Each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. s2 is a single bond, or a linear or branched alkylene group having 1 to 5 carbon atoms. s3 Each R is independently a hydrogen atom, a hydrocarbon group or a fluorinated hydrocarbon group having 1 to 15 carbon atoms, or an acid-labile group.s3 When it is a hydrocarbon group or a fluorinated hydrocarbon group, an ether bond or a carbonyl group may be inserted between the carbon-carbon bonds. s4 is a (u+1)-valent hydrocarbon group or a fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer of 1 to 3. s5 are each independently a hydrogen atom, or -C(=O)-OR sa The group represented by R sa It is a fluorinated hydrocarbon group having 1 to 20 carbon atoms. s6 It is a hydrocarbon group or a fluorinated hydrocarbon group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be inserted between the carbon-carbon bonds.

[0494] R s1 The hydrocarbon group represented by is preferably a saturated hydrocarbon group and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbon groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Among these, those having 1 to 6 carbon atoms are preferred.

[0495] R s2 The alkylene group represented by is preferably a saturated alkylene group, which may be linear, branched or cyclic. Specific examples thereof include methylene, ethylene, propylene, butylene and pentylene.

[0496] R s3 or R s6 The hydrocarbon group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbon groups, alkenyl groups, alkynyl groups, and other aliphatic unsaturated hydrocarbon groups, with saturated hydrocarbon groups being preferred. s1 Examples of the hydrocarbon group represented by R include n-undecyl, n-dodecyl, tridecyl, tetradecyl, pentadecyl and the like. s3 or R s6 The fluorinated hydrocarbon groups represented by can be exemplified by groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbon groups are substituted with fluorine atoms. As mentioned above, these carbon-carbon bonds may be interposed with an ether bond or a carbonyl group.

[0497] R s3 Specific examples of the acid-labile group represented by include the groups represented by the aforementioned formulae (L1) to (L4), trialkylsilyl groups wherein each alkyl group is an alkyl group having 1 to 6 carbon atoms, and alkyl groups having an oxo group and 4 to 20 carbon atoms.

[0498] R s4 The (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by may be linear, branched, or cyclic. Specific examples thereof include groups obtained by further excluding u hydrogen atoms from the aforementioned hydrocarbon group or fluorinated hydrocarbon group.

[0499] R sa The fluorinated hydrocarbon group represented by is preferably saturated and may be linear, branched, or cyclic. Specific examples include those in which some or all of the hydrogen atoms of the aforementioned hydrocarbon groups are substituted with fluorine atoms, such as trifluoromethyl, 2,2,2-trifluoroethyl, 3,3,3-trifluoro-1-propyl, 3,3,3-trifluoro-2-propyl, 2,2,3,3-tetrafluoropropyl, 1,1,1,3,3,3-hexafluoroisopropyl, 2,2,3,3,4,4,4-heptafluorobutyl, 2,2,3,3,4,4,5,5-octafluoropentyl, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl, 2-(perfluorobutyl)ethyl, 2-(perfluorohexyl)ethyl, 2-(perfluorooctyl)ethyl, and 2-(perfluorodecyl)ethyl.

[0500] The repeating unit represented by any of formulae (7A) to (7E) may be exemplified by the following, but is not limited thereto. B Same as above.

[0501] [Chemistry 132]

[0502]

[0503] [Chemistry 133]

[0504]

[0505] [Chemistry 134]

[0506]

[0507] [Chemistry 135]

[0508]

[0509] [Chemistry 136]

[0510]

[0511] [Chemistry 137]

[0512]

[0513] The aforementioned polymeric surfactant may further comprise repeating units other than the repeating units represented by formulae (7A) to (7E). Examples of such repeating units include repeating units derived from methacrylic acid and α-trifluoromethylacrylic acid derivatives. In the polymeric surfactant, the content of the repeating units represented by formulae (7A) to (7E) is preferably 20 mol% or greater, more preferably 60 mol% or greater, and even more preferably 100 mol% of the total repeating units.

[0514] The Mw of the polymeric surfactant is preferably 1,000 to 500,000, more preferably 3,000 to 100,000, and the Mw / Mn is preferably 1.0 to 2.0, more preferably 1.0 to 1.6.

[0515] Methods for synthesizing the aforementioned polymeric surfactants include polymerizing the repeating units represented by formulas (7A) to (7E) and, if necessary, unsaturated bond-containing monomers that provide other repeating units in an organic solvent, adding a free radical initiator, and heating. Examples of organic solvents used in the polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionic acid), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50-100°C. The reaction time is preferably 4-24 hours. Acid-labile groups may be directly introduced into the monomers, or they may be protected or partially protected after polymerization.

[0516] When synthesizing the aforementioned polymeric surfactant, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. The amount of such chain transfer agent added is preferably 0.01 to 10 mol % relative to the total molar amount of the monomers to be polymerized.

[0517] When the resist composition of the present invention includes a surfactant (F), its content is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 10 parts by mass, relative to 80 parts by mass of the base polymer (A). If the content of the surfactant (F) is 0.1 parts by mass or greater, the receding contact angle of the resist film surface with water is sufficiently improved. If the content of the surfactant (F) is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is slow, thereby sufficiently maintaining the height of the formed fine pattern. The surfactant (F) may be used alone or in combination of two or more.

[0518] [(G) Other ingredients]

[0519] In the resist composition of the present invention, (G) other components may also include compounds that decompose with acid and generate acid (acid-proliferating compounds), organic acid derivatives, fluorinated alcohols, compounds with a Mw of 3000 or less that change their solubility in the developer due to the action of acid (anti-dissolution agents), etc. The acid-proliferating compounds can refer to the compounds described in Japanese Patent Application Laid-Open No. 2009-269953 or Japanese Patent Application Laid-Open No. 2010-215608. When the acid-proliferating compound is included, its content is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, relative to 80 parts by mass of the base polymer (A). If the content is too high, it is difficult to control the diffusion of acid, which may lead to degradation of resolution and pattern shape. The organic acid derivatives, fluorinated alcohols, and anti-dissolution agents can refer to the compounds described in Japanese Patent Application Laid-Open No. 2009-269953 or Japanese Patent Application Laid-Open No. 2010-215608.

[0520] [Pattern Formation Method]

[0521] The pattern forming method of the present invention comprises the following steps: forming a resist film on a substrate using the resist composition, exposing the resist film using high-energy rays, and developing the exposed resist film using a developer.

[0522] The aforementioned substrate, for example, can be a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.), or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.).

[0523] The resist film can be formed by, for example, applying the resist composition onto a substrate using a spin coating method to a film thickness of preferably 0.05 to 2 μm, placing the resist composition on a heating plate, and pre-baking the pre-baked film at preferably 60 to 150° C. for 1 to 10 minutes, more preferably 80 to 140° C. for 1 to 5 minutes.

[0524] The high energy radiation used for exposure of the resist film includes KrF excimer laser, ArF excimer laser, EB, EUV, etc. When KrF excimer laser, ArF excimer laser, or EUV is used for exposure, the exposure dose is preferably 1 to 200 mJ / cm by using a mask for forming a target pattern. 2 , more preferably 10 to 100 mJ / cm 2 When EB is used, a mask for forming a target pattern or a direct exposure dose is preferably 1 to 300 μC / cm 2 , preferably 10 to 200 μC / cm 2 way of irradiation.

[0525] Furthermore, in addition to the conventional exposure method, an immersion method can be used in which a liquid with a refractive index of 1.0 or higher is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0526] The water-insoluble protective film is used to prevent elution from the resist film and improve the water slipperiness of the film surface. It is broadly classified into two types. One is an organic solvent-removable type that must be removed using an organic solvent that does not dissolve the resist film before alkaline aqueous solution development. The other is an alkaline aqueous solution-soluble type that is soluble in an alkaline developer and removes the protective film simultaneously with the soluble portion of the resist film. The latter is preferably based on a water-insoluble but alkaline developer-soluble polymer containing 1,1,1,3,3,3-hexafluoro-2-propanol residues, which is soluble in alcoholic solvents with 4 or more carbon atoms, etheric solvents with 8 to 12 carbon atoms, or mixed solvents thereof. Alternatively, the water-insoluble but alkaline developer-soluble surfactant can be dissolved in an alcoholic solvent with 4 or more carbon atoms, an etheric solvent with 8 to 12 carbon atoms, or mixed solvents thereof.

[0527] After exposure, PEB can be performed. PEB can be performed, for example, by heating on a hot plate, preferably at 60 to 150° C. for 1 to 5 minutes, more preferably at 80 to 140° C. for 1 to 3 minutes.

[0528] Development is performed using a developer such as an alkaline aqueous solution of tetramethylammonium hydroxide (TMAH) preferably at a concentration of 0.1 to 5% by mass, more preferably 2 to 3% by mass, and by conventional methods such as dipping, puddle, or spraying for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes. The exposed portion is dissolved, and a target pattern is formed on the substrate.

[0529] After the resist film is formed, pure water rinsing may be performed to extract the acid generator and the like from the film surface, to wash away particles, or to remove water remaining on the film after exposure.

[0530] Furthermore, a double patterning method can be used to form a pattern. Examples of double patterning methods include a trench method in which a base with a 1:3 trench pattern is processed by a first exposure and etching, and then a 1:3 trench pattern is formed by offsetting the position and performing a second exposure to form a 1:1 pattern; and a line method in which a first base with a 1:3 isolated residual pattern is processed by a first exposure and etching, and then a second base with a 1:3 isolated residual pattern is formed under the first base by offsetting the position and performing a second exposure to form a 1:3 isolated residual pattern, thereby forming a 1:1 pattern with half the pitch.

[0531] In the pattern forming method of the present invention, an organic solvent may be used as a developer in place of the alkaline aqueous solution to employ a negative tone development method in which the unexposed portion is dissolved. In the organic solvent development, as a developer, 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, butyl acetate, isoamyl acetate, propyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl valerate, methyl pentenoate, methyl croton ... Ethyl beanate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, amyl lactate, isoamyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, ethyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more.

[0532] Example

[0533] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0534] [1] Synthesis of base polymer

[0535] The monomers used in the synthesis of the base polymer are as follows.

[0536] [Chemistry 138]

[0537]

[0538] [Chemistry 139]

[0539]

[0540] [Chemistry 140]

[0541]

[0542] [Chemistry 141]

[0543]

[0544] Synthesis was performed with reference to Japanese Patent Application Publication No. 2018-095853

[0545] [Synthesis Example 1] Synthesis of Polymer P-1

[0546] Under a nitrogen atmosphere, a monomer-polymerization initiator solution was prepared in a flask containing 1.9 g of monomer a1-0, 50.1 g of monomer a1-1, 16.2 g of monomer b2-1, 49.7 g of monomer c1, 3.96 g of V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 127 g of MEK. In another flask under a nitrogen atmosphere, 46 g of MEK was heated to 80°C while stirring, and the monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition was complete, the polymerization solution was stirred for 2 hours while maintaining the temperature at 80°C, then cooled to room temperature. The resulting polymerization solution was added dropwise to 2000 g of vigorously stirred hexane, and the precipitated polymer was filtered. The resulting polymer was then washed twice with 600 g of hexane and vacuum-dried at 50°C for 20 hours to obtain polymer P-1 as a white powder (yield 119.4 g, 98%). The Mw of polymer P-1 was 10,900, and Mw / Mn was 1.82. Mw is a polystyrene-equivalent measurement value obtained by GPC using DMF as a solvent.

[0547] [Chemistry 142]

[0548]

[0549] [Synthesis Examples 2 to 14] Synthesis of Polymers P-2 to P-14

[0550] The polymers shown in Table 1 below were synthesized in the same manner as in Synthesis Example 1 except that the types and blending ratios of the monomers were changed.

[0551] [Table 1]

[0552]

[0553] [2] Preparation of resist composition

[0554] [Examples 1-1 to 1-14, Comparative Examples 1-1 to 1-6]

[0555] Polymers (P-1 to P-14), hypervalent iodine compounds (I-1 to I-3), a photoacid generator (PAG-1), and quenchers (Q-1 and Q-2) having the compositions shown in Table 2 below were dissolved in a solvent containing 0.01% by mass of a surfactant (PF-636, manufactured by OMNOVA), and the resulting solution was filtered through a 0.2 μm Teflon (registered trademark) filter to prepare resist compositions (R-01 to R-14). Furthermore, comparative resist compositions (CR-01 to CR-06) were prepared by mixing polymers, a photoacid generator, a sensitivity adjuster, a hypervalent iodine compound, a solvent, and 0.01% by weight of a surfactant (PF-636, manufactured by OMNOVA) having the compositions shown in Table 3 below. The mixture was then filtered through a 0.2 μm Teflon (registered trademark) filter.

[0556] [Table 2]

[0557]

[0558]

[0559] [Table 3]

[0560]

[0561] In Tables 2 and 3, the components are as follows.

[0562] Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (diacetone alcohol)

[0563] HBM (2-hydroxyisobutyric acid methyl ester)

[0564] Photoacid generator: PAG-1

[0565] [Chemistry 143]

[0566]

[0567] Quencher: Q-1, Q-2

[0568] [Chemistry 144]

[0569]

[0570] Hypervalent iodine compounds: I-1, I-2, I-3

[0571] [Chemistry 145]

[0572]

[0573] [3]EUV lithography evaluation

[0574] [Examples 2-1 to 2-14, Comparative Examples 2-1 to 2-6]

[0575] Each resist composition (R-01 to R-14, CR-01 to CR-06) was spin-coated onto a Si substrate on which a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. was formed. A 50 nm thick resist film was pre-baked at 100°C for 60 seconds using a hot plate. An LS pattern with a size of 18 nm and a pitch of 36 nm was exposed on the wafer using an EUV scanner NXE3300 manufactured by ASML (NA 0.33, σ 0.9 / 0.6, dipole illumination). The exposure dose and focus (exposure dose pitch: 1 mJ / cm) were varied. 2 The resist film was exposed while immersing (with a focal pitch of 0.020 μm). After exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 4 and 5. This was then developed by immersion in a 2.38% by mass TMAH aqueous solution for 30 seconds, rinsed with a rinse material containing a surfactant, and spin-dried to obtain a positive pattern. The developed LS pattern was observed using a Hitachi Advanced Technologies Co., Ltd. long-range scanning electron microscope (CG6300). Sensitivity, LWR, DOF, and collapse threshold were evaluated using the following methods. The results are summarized in Tables 4 and 5.

[0576] [Sensitivity evaluation]

[0577] The optimal exposure dose Eop (mJ / cm2) for obtaining a LS pattern with a line width of 18 nm and a pitch of 36 nm was determined. 2 ) and define it as sensitivity.

[0578] [LWR evaluation]

[0579] The LS pattern obtained by irradiation with Eop is measured at 10 locations along the length of the line. From the results, the value (3σ) tripled from the standard deviation (σ) is calculated as LWR. The smaller the value, the less roughness and the more uniform the line width.

[0580] [DOF evaluation]

[0581] For DOF evaluation, the focal range formed by the range of ±10% (16.2 to 19.8 nm) of the 18 nm size in the aforementioned LS pattern was determined. The larger the value, the wider the depth of focus.

[0582] [Evaluation of Collapse Limit of Line Pattern]

[0583] The line size of each exposure dose at the best focus of the LS pattern was measured at 10 locations along the longitudinal direction. The thinnest line size obtained without collapse was defined as the collapse limit size. The smaller the value, the better the collapse limit.

[0584] [Table 4]

[0585]

[0586] [Table 5]

[0587]

[0588] From the results shown in Tables 4 and 5, it was confirmed that the resist composition of the present invention had high resolution and was excellent in various lithographic properties.

Claims

1. A resist composition comprising: (A) a base polymer comprising a polymer containing a repeating unit having an acid-labile group and a repeating unit having a carboxyl group, (B) organic solvents, and (C) a hypervalent iodine compound represented by the following formula (1), Wherein, n is an integer from 0 to 5, R 1 and R 2 are each independently a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may contain a hetero atom, and R 1 and R 2 They may also be bonded to each other and to the carbon atoms to which they are bonded and the atoms between the carbon atoms to form a ring. R 3 It is a hydrocarbon group having 1 to 40 carbon atoms which may contain a halogen atom or a heteroatom.

2. The resist composition according to claim 1, wherein The repeating unit having an acid-labile group is represented by the following formula (a1) or (a2), Wherein, a is an integer from 0 to 4, R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, X 1 is a single bond, phenylene, naphthylene or *-C(=O)-OX 11 -, X 11 is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, wherein the saturated alkylene group may contain at least one member selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, and a lactone ring. X 2 is a single bond or *-C(=O)-O-, * indicates atomic bonds to carbon atoms of the main chain, R 11 is a halogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may contain a hetero atom, AL 1 and AL 2 Each is independently an acid-labile group.

3. The resist composition according to claim 1, wherein The repeating unit having a carboxyl group is represented by the following formula (b), Where R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, Y 1 is a single bond, phenylene, naphthylene or *-C(=O)-OY 11 -, Y 11 It is a saturated alkylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group. The saturated alkylene group may contain at least one selected from a hydroxyl group, an ether bond, an ester bond, and a lactone ring. * represents an atomic bond to a carbon atom of the main chain.

4. The resist composition according to claim 1, wherein The polymer further comprises at least one repeating unit selected from the group consisting of the repeating units represented by the following formulae (c1) and (c2), In the formula, b is 1 or 2, c is an integer from 0 to 4, R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group, Y 2 is a single bond or *-C(=O)-O-, * represents an atomic bond to a carbon atom of the main chain, R 21 is a group having 1 to 20 carbon atoms containing at least one member selected from the group consisting of a hydroxyl group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-), R 22 It is a hydrocarbon group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom.

5. The resist composition according to claim 1, wherein The polymer further comprises a repeating unit having a photoacid generating group. The resist composition according to claim 1 , further comprising (D) a photoacid generator. The resist composition according to claim 1 , further comprising (E) a quencher. The resist composition according to claim 1 , further comprising (F) a surfactant.

9. A pattern forming method comprising the steps of forming a resist film on a substrate using the resist composition according to any one of claims 1 to 8, exposing the resist film using a KrF excimer laser, an ArF excimer laser, an electron beam or extreme ultraviolet light, and developing the exposed resist film using a developer.

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