Polymer, chemically amplified resist composition, and pattern forming method

Abstract

To provide: a polymer used for a chemically amplified resist composition which exhibits excellent solvent solubility, high sensitivity, high contrast, and excellent lithographic performance such as EL, LWR, CDU and DOF in photolithography using a high energy rays, is resistant to pattern collapse even in fine pattern formation, and also has excellent etching resistance; a chemically amplified resist composition containing the polymer; and a pattern forming method using the chemically amplified resist composition.SOLUTION: The polymer contains: a repeating unit represented by the following formula (a); and a repeating unit which is derived from an onium salt compound containing a fluorosulfonic acid anion having a polymerizable group and an aromatic ring structure substituted with an iodine atom and generates an acid upon exposure.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polymer, a chemically amplified resist composition, and a patterning method.

Background Art

[0002] With the increasing integration density and speed of LSIs, the miniaturization of pattern rules has been rapidly progressing. In particular, the expansion of the flash memory market and the increase in storage capacity have been driving miniaturization. As the most advanced miniaturization technology, mass production of 65 nm node devices by ArF lithography is underway, and preparation for mass production of 45 nm node devices by next-generation ArF immersion lithography is in progress. As for next-generation 32 nm node devices, candidates include immersion lithography using an ultra-high NA lens that combines a liquid with a higher refractive index than water, a high refractive index lens, and a high refractive index resist film, extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, double patterning lithography of ArF lithography, etc., and studies are being advanced.

[0003] As miniaturization progresses and approaches the diffraction limit of light, the contrast of light decreases. Due to the decrease in the contrast of light, in a positive resist film, the resolution of hole patterns and trench patterns and the focus margin decrease.

[0004] As patterns are miniaturized, the line width roughness (LWR) of line patterns and the critical dimension uniformity (CDU) of hole patterns are regarded as problems. The effects of uneven distribution and aggregation of the base polymer and acid generator, and the effect of acid diffusion have been pointed out. Furthermore, as the resist film becomes thinner, the LWR tends to increase, and the deterioration of the LWR due to thinning accompanying the progress of miniaturization has become a serious problem.

[0005] In EUV lithography resist compositions, it is necessary to simultaneously achieve high sensitivity, high resolution, and low LWR. When the acid diffusion distance is shortened, the LWR decreases but the sensitivity decreases. For example, by lowering the post-exposure bake (PEB) temperature, the LWR decreases but the sensitivity decreases. Even if the amount of quencher added is increased, the LWR decreases but the sensitivity decreases. It is necessary to break the trade-off relationship between sensitivity and LWR.

[0006] In order to suppress acid diffusion, a resist compound containing a repeating unit derived from an onium salt of a sulfonic acid having a polymerizable unsaturated bond has been proposed (Patent Document 1). Such a so-called polymer-bound acid generator has the characteristic that the acid diffusion is very short because a polymer-type sulfonic acid is generated by exposure. Also, by increasing the ratio of the acid generator, the sensitivity can be improved. In the case of an additive acid generator, increasing the amount added results in higher sensitivity, but in this case, the acid diffusion distance also increases. Since the acid diffuses non-uniformly, when the acid diffusion increases, the LWR and CDU deteriorate. It can be said that the polymer-type acid generator has high ability in terms of the balance of sensitivity, LWR, and CDU.

[0007] Since the iodine atom has a very large absorption of EUV with a wavelength of 13.5 nm, the effect of generating secondary electrons from the iodine atom during exposure has been confirmed and it has attracted attention in EUV lithography. Patent Document 2 describes a photoacid generator in which an iodine atom is introduced into the anion, and Patent Document 3 describes a polymerizable group-containing photoacid generator in which an iodine atom is introduced into the anion. Although some improvement in lithography performance has been confirmed, the iodine atom does not have high solubility in organic solvents and there is concern about precipitation in the solvent.

[0008] Patent Documents 4 and 5 propose a resist material that uses a polymer copolymerized with salicylic acid having a polymerizable group or a protected form thereof as a base polymer. Salicylic acid has a structure with a hydroxy group and a carboxy group on adjacent carbons of an aromatic ring, and the substituents form a hydrogen bond with each other. As a result, although it has two polar groups, it has relatively high solubility in organic solvents and is relatively easy to copolymerize with other monomers. However, the performance as a resist material is still not satisfactory, and the development of a resist material useful for further fine pattern formation is required.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0010] In an acid-catalyzed chemically amplified resist composition, it is desired to develop a resist composition that can be more sensitive, improve the LWR of line patterns and the CDU of hole patterns, and also has excellent etching resistance after pattern formation.

[0011] The present invention has been made in view of the above circumstances, and particularly in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), EUV, etc., it has excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance such as exposure latitude (EL), LWR, CDU, depth of focus (DOF), etc., and is also strong against pattern collapse and excellent in etching resistance in fine pattern formation. An object of the present invention is to provide a polymer used in a chemically amplified resist composition, the chemically amplified resist composition containing the polymer, and a pattern forming method using the chemically amplified resist composition.

Means for Solving the Problems

[0012] As a result of intensive studies to achieve the above object, the present inventors have found that a polymer containing a repeating unit having a cyclic acetal structure condensed with an aromatic ring and a repeating unit derived from an onium salt containing a fluorosulfonic acid anion containing an aromatic ring structure substituted with an iodine atom as a polymer-bonded acid generator is used. By doing so, a chemically amplified resist composition having high sensitivity, improved LWR and CDU, high contrast, high resolution, and excellent etching resistance can be obtained, and the present invention has been completed.

[0013] That is, the present invention provides the following polymer, chemically amplified resist composition, and pattern forming method. 1. A polymer containing a repeating unit represented by the following formula (a) and a repeating unit derived from an onium salt compound containing a fluorosulfonic acid anion having a polymerizable group and an aromatic ring structure substituted with an iodine atom, and generating an acid upon exposure.

Chemical Formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Effects of the Invention

[0014] The polymer containing a repeating unit represented by formula (a) and an onium salt compound containing a fluorosulfonic acid anion having a polymerizable group and an aromatic ring structure substituted with an iodine atom, which generates an acid upon exposure, has good solvent solubility, and since the atomic weight of the iodine atom is large and the generated acid has a structure bonded to the polymer main chain, it has the characteristic of low acid diffusion. As a result, it is possible to prevent a decrease in resolution due to blurring of acid diffusion and improve LWR and CDU. Further, since the absorption by iodine atoms of EUV with a wavelength of 13.5 nm is very large, secondary electrons are generated from iodine atoms during exposure, resulting in increased sensitivity. As a result, it is possible to construct a chemically amplified resist composition having high sensitivity and improved LWR and CDU. Further, the repeating unit represented by formula (a) has an acid-labile structure derived from a cyclic acetal, and a deprotection reaction proceeds by the action of an acid, generating two polar groups. Thereby, the contrast between the exposed portion and the unexposed portion is improved. Furthermore, the aromatic ring in the repeating unit acts as a good etching resistance group and is suitable for forming a fine pattern.

Mode for Carrying Out the Invention

[0015] [Polymer] The polymer of the present invention contains a repeating unit represented by the following formula (a) (hereinafter, also referred to as repeating unit a).

Chem.

[0016] In formula (a), m1 is 0 or 1. When m1 is 0, it is a benzene ring, and when m1 is 1, it is a naphthalene ring. From the viewpoint of solvent solubility, it is preferably a benzene ring with m1 = 0. m2 is an integer from 0 to 3 when m1 is 0, and an integer from 0 to 5 when m1 is 1. From the viewpoint of raw material procurement, m2 is preferably 0, 1, 2, or 3, and more preferably 0, 1, or 2.

[0017] In formula (a), R Ais, independently of each other, a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Among these, a hydrogen atom or a methyl group is preferable, and a hydrogen atom is more preferable.

[0018] In formula (a), X A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond to a carbon atom of the main chain. Among these, a single bond or *-C(=O)-O- is preferable, and a single bond is more preferable.

[0019] In formula (a), R 1 and R 2 are, independently of each other, a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group; alkenyl groups having 2 to 20 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclohexenyl group; aryl groups having 2 to 20 carbon atoms such as phenyl group, naphthyl group; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group; groups obtained by combining these, and the like. Further, part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and the -CH of the hydrocarbyl group 2Part of the "-" may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0020] Also, R 1 and R 2 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. Specific examples of the ring formed at this time include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, etc. Also, part or all of the hydrogen atoms in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and part of the -CH 2 - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0021] In formula (a), R 3 is a halogen atom, a hydroxy group, a cyano group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, or -N(R 3A )(R 3B ). R 3A and R 3Bis, independently of each other, a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, more preferably a fluorine atom or an iodine atom. The hydrocarbyl moieties of the hydrocarbyl group, hydrocarbyloxy group, hydrocarbyloxycarbonyl group and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include those exemplified as the hydrocarbyl groups represented by R 1 and R 2 . Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of -CH 2 - of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. When m2 is 2 or more, each R 3 may be the same as or different from each other.

[0022] Further, when m2 is 2 or more, a plurality of R 3 may be bonded to each other to form a ring together with the carbon atoms of the aromatic ring to which they are bonded. Specific examples of the ring formed at this time include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, etc. Further, some or all of the hydrogen atoms in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and -CH 2- may be partially substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0023] In formula (a), L A is a single bond, an aliphatic hydrocarbylene group having 1 to 4 carbon atoms, a carbonyl group, a sulfonyl group, or a group obtained by combining these. Among these, from the viewpoint of raw material procurement, it is preferably a single bond, a carbonyl group, or a sulfonyl group, and more preferably a single bond or a carbonyl group from the viewpoint of the polar group generated after the reaction.

[0024] In formula (a), L B and L C are each independently an oxygen atom or a sulfur atom. However, L A and L C must be bonded to adjacent carbon atoms of the aromatic ring. L B and L C may be the same as or different from each other. However, from the viewpoint of reactivity, it is preferable that both L B and L C are oxygen atoms.

[0025] Specific examples of the repeating unit a include, but are not limited to, those shown below. In the following formulas, R A is the same as described above. Also, the bonding positions of various substituents on the aromatic ring may be interchanged with each other.

Chemical formula

[0026]

Chemical formula

[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0035]

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[0048] [Chemistry]

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[0050] [Chemistry]

[0051] [Chemistry]

[0052] [Chemistry]

[0053] [Chemistry]

[0054] [Chemistry]

[0055] [Chemistry]

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[0058] [Chemistry]

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[0063]

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[0064]

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[0065]

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[0067]

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[0069]

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[0070] [Chemistry]

[0071] [Chemistry]

[0072] [Chemistry]

[0073] [Chemistry]

[0074] [Chemistry]

[0075] The polymer of the present invention further derives from an onium salt compound containing a fluorosulfonic acid anion having a polymerizable group and an aromatic ring structure substituted with an iodine atom, and generates an acid upon exposure (hereinafter, also referred to as repeating unit b). It is characterized by including. As the repeating unit b, those represented by the following formula (b) are preferred. [Chemistry]

[0076] In formula (b), n1 is 0 or 1. When n1 is 0, it is a benzene ring, and when n1 is 1, it is a naphthalene ring. From the viewpoint of solvent solubility, it is preferably a benzene ring with n1 being 0. n2 is 0 or 1. When n2 is 0, it is a benzene ring, and when n2 is 1, it is a naphthalene ring. From the viewpoint of solvent solubility, it is preferably a benzene ring with n2 being 0. n3 is an integer from 0 to 4. From the viewpoint of raw material procurement, n3 is preferably 0, 1 or 2, and more preferably 0 or 1. n4 is an integer from 0 to 4, preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and even more preferably 0 or 1. n5 is an integer from 1 to 6. The larger the number of iodine atoms in the anion structure, the higher the absorption particularly for EUV. However, there is a concern that the solvent solubility becomes poor and precipitation occurs in the resist composition. Therefore, n5 is preferably 1, 2 or 3, and more preferably 1 or 2. However, when n2 is 0, 1 ≤ n4 + n5 ≤ 4, and when n2 is 1, 1 ≤ n4 + n5 ≤ 6. n6 is an integer from 0 to 4, preferably 0, 1, 2 or 3, and more preferably 1. n7 is 0 or 1. n8 is 0 or 1.

[0077] In formula (b), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Among these, it is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0078] In formula (b), the iodine atom in the aromatic ring of the anion is preferably bonded to the ortho position of the carbon atom to which L E is bonded. Since the iodine atom is an element with a large atomic radius, the rotation of the bonding axes of the aromatic ring to which the polymerizable group is bonded and the aromatic ring to which the iodine atom is bonded is suppressed, and the rigidity of the polymer is improved.

[0079] In formula (b), R 11is a halogen atom, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a hetero atom, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a hetero atom. The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, more preferably a fluorine atom or an iodine atom. The hydrocarbyl moiety of the hydrocarbyl group, hydrocarbyloxy group and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group; alkenyl groups having 2 to 20 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclohexenyl group; aryl groups having 2 to 20 carbon atoms such as phenyl group, naphthyl group; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group; groups obtained by combining these, etc. Further, part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and the -CH of the hydrocarbyl group 2- part may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. When n3 is 2, 3, or 4, each R 11 may be the same as or different from each other.

[0080] Also, when n3 is 2, 3, or 4, a plurality of R 11 may combine with each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. Specific examples of the ring formed at this time include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, etc. Also, some or all of the hydrogen atoms in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of -CH 2 - in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0081] In formula (b), R 12is a halogen atom other than an iodine atom, a C1-C20 hydrocarbyl group which may contain a dinitro group or a hetero atom, a C1-C20 hydrocarbyloxy group which may contain a hetero atom, or a C1-C20 hydrocarbylthio group which may contain a hetero atom. Specific examples of the halogen atom other than the iodine atom include a fluorine atom, a chlorine atom, a bromine atom and the like. The hydrocarbyl moieties of the hydrocarbyl group, the hydrocarbyloxy group and the hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include those exemplified as the hydrocarbyl group represented by R 11 and are not limited thereto. When n4 is 2, 3 or 4, each R 12 may be the same as or different from each other.

[0082] Also, when n4 is 2, 3 or 4, a plurality of R 12 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0083] In formula (b), L D , L E and L F are each independently a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a sulfonic acid amide bond, a carbonate bond or a carbamate bond. Among these, L D is preferably a single bond, an ether bond, an ester bond or a sulfonic acid ester bond, and more preferably an ester bond or a sulfonic acid ester bond. L E is preferably a single bond, an ether bond or an ester bond, and more preferably a single bond. L F is preferably a single bond, an ether bond, an ester bond or a sulfonic acid ester bond, and more preferably an ether bond or an ester bond.

[0084] In formula (b), X Lis a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be linear, branched or cyclic, and specific examples thereof include an alkanediyl group, a cyclic saturated hydrocarbylene group, etc. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, etc.

[0085] X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom represented by are as follows, but are not limited thereto. In the following formulas, * represents a bond with L D and L E respectively.

Chemical formula

[0086]

Chemical formula

[0087]

Chemical formula

[0088]

Chemical formula

[0089] Among these, X L -0 to X L -22, X L -29 to X L -34, and X L -47 to X L -58 are preferred.

[0090] In formula (b), Q 1 and Q 2is, independently of each other, a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. As the fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a trifluoromethyl group is preferred.

[0091] In formula (b), Q 3 and Q 4 are, independently of each other, a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. As the fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a trifluoromethyl group is preferred. Q 3 and Q 4 are more preferably a fluorine atom.

[0092] In formula (b), -[C(Q 1 )(Q 2 )] n6 -C(Q 3 )(Q 4 )-SO 3 - Specific examples of the partial structure represented by are preferably those shown below, but are not limited thereto. In the following formulas, * represents a bond to L F

Chemical formula

[0093] Among these, Acid-1 to Acid-7 are preferred, and Acid-1 to Acid-3, Acid-6 and Acid-7 are more preferred.

[0094] As the repeating unit b, those represented by the following formula (b1) are preferred.

Chemical formula

[0095] As the repeating unit represented by formula (b1), those represented by the following formula (b2) are preferable.

Chemical formula

[0096] Examples of the anion of the monomer that gives the repeating unit b include, but are not limited to, those shown below. In the following formulas, R A , Q 1 , R 12 , n4 and n5 are the same as those described above. Also, the bonding positions of the various substituents on the aromatic ring may be interchanged with each other.

Chemical formula

[0097]

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[0098]

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[0099]

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[0166] [Chemical formula]

[0167] [Chemical formula]

[0168] [Chemical formula]

[0169] [Chemical formula]

[0170] [Chemical formula]

[0171] [Chemical formula]

[0172] Examples of other anions also include the anions described in paragraphs

[0023] to

[0029] of Japanese Patent No. 6973274.

[0173] In formula (b), Z + is an onium cation. As the onium cation, a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2) is preferable. [Chemical formula]

[0174] In formulas (cation-1) and (cation-2), R ct1 ~R ct5is independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a halogen atom or a heteroatom.

[0175] R ct1 ~R ct5 Specific examples of the halogen atom represented by R ct1 ~R ct5 include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.

[0176] R ct1 ~R ct5 The hydrocarbyl group represented by R ct1 ~R ct5 may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include an alkyl group having 1 to 30 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group; a cyclic saturated hydrocarbyl group having 3 to 30 carbon atoms such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, an adamantyl group; an alkenyl group having 2 to 30 carbon atoms such as a vinyl group, an allyl group, a propenyl group, a butenyl group, a hexenyl group; a cyclic unsaturated hydrocarbyl group having 3 to 30 carbon atoms such as a cyclohexenyl group; an aryl group having 6 to 30 carbon atoms such as a phenyl group, a naphthyl group, a thienyl group; an aralkyl group having 7 to 30 carbon atoms such as a benzyl group, a 1-phenylethyl group, a 2-phenylethyl group; a group obtained by combining these, etc. Among them, an aryl group is preferred. Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, and a part of -CH 2 - of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, and as a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0177] Also, R ct1 ​​and R ct2 may combine with each other to form a ring together with the sulfur atom to which they are attached. Specific examples of the structure of the ring include those represented by the following formulae and the like.

Chemical formula

[0178] Specific examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below.

Chemical formula

[0179]

Chemical formula

[0180]

Chemical formula

[0181]

Chemical formula

[0182]

Chemical formula

[0183]

Chemical formula

[0184]

Chemical formula

[0185]

Chemical formula

[0186]

Chem.

[0187]

Chem.

[0188]

Chem.

[0189]

Chem.

[0190]

Chem.

[0191]

Chem.

[0192]

Chem.

[0193]

Chem.

[0194]

Chem.

[0195]

Chem.

[0196] [Chemical]

[0197] [Chemical]

[0198] [Chemical]

[0199] [Chemical]

[0200] [Chemical]

[0201] [Chemical]

[0202] [Chemical]

[0203] [Chemical]

[0204] [Chemical]

[0205] Specific examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [Chemical]

[0206] [Chemical formula]

[0207] Specific examples of the repeating unit b include any combination of the anions and cations described above.

[0208] The monomer that provides the repeating unit b can be synthesized, for example, in the same manner as the sulfonium salt having a polymerizable anion described in Japanese Patent No. 5201363, but is not limited thereto.

[0209] The polymer of the present invention is a polymer - bound photoacid generator that functions as a base polymer and a photoacid generator in a chemically amplified resist composition. As structural features of the polymer of the present invention, it includes a repeating unit a having a cyclic acetal structure fused to an aromatic ring, and a repeating unit b that generates an acid upon exposure, which is derived from an onium salt compound containing a fluorosulfonic acid anion having a polymerizable group and an aromatic ring structure substituted with an iodine atom. The cyclic acetal structure fused to the aromatic ring has good solvent solubility and also acts as an acid - labile group. Due to the action of an acid, a deprotection reaction proceeds to generate two polar groups. This improves the contrast between the exposed and unexposed areas. Also, the iodine atom contained in the repeating unit b has an extremely large absorption of EUV with a wavelength of 13.5 nm. During exposure, secondary electrons are generated, and the energy of the secondary electrons is transferred to the photoacid generator, promoting its decomposition, thereby achieving high sensitivity. Further, the polymerizable group having a styrene or vinylnaphthalene structure is more rigid than polymerizable groups such as methacrylic acid esters, and improves the glass transition temperature (Tg) of the polymer. Moreover, the aromatic rings within or between the base polymers interact (π - π stacking effect), causing the base polymers to be regularly arranged, and it is considered that resistance to pattern collapse against the developer is exhibited even during fine pattern formation. Also, in the etching process after fine pattern formation, excellent etching resistance is exhibited due to the presence of aromatic rings directly connected to the main chain. Although there is a concern that the iodine atom has poor solvent solubility, before exposure, the polymer has high solvent solubility due to the cyclic acetal structure contained in the repeating unit a, so precipitation in the solvent is suppressed. When developing with an alkaline developer after exposure, the polar groups generated after the deprotection of the acetal structure have high affinity for the alkaline developer, so the exposed areas are effectively removed, reducing the risk of development defects. Due to these synergistic effects, by using the polymer of the present invention as a base polymer in a chemically amplified resist composition, it is possible to form patterns that are excellent in LWR of line patterns and CDU of hole patterns and are resistant to pattern collapse. The polymer of the present invention is particularly suitable as a material for a chemically amplified positive - type resist composition.

[0210] The polymer preferably further contains a repeating unit represented by the following formula (c1) (hereinafter also referred to as repeating unit c).

Chemical formula

[0211] In formula (c1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 21 is a halogen atom, a nitro group, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. a is an integer of 1 to 4. b is an integer of 0 to 3. However, 1 ≤ a + b ≤ 5.

[0212] Specific examples of the repeating unit c include, but are not limited to, those shown below. In the following formulas, R A is the same as described above.

Chemical formula

[0213]

Chemical formula

[0214]

Chemical formula

[0215]

Chemical formula

[0216]

Chem.

[0217] The polymer may further contain a repeating unit represented by the following formula (d1) (hereinafter also referred to as repeating unit d1) or a repeating unit represented by the following formula (d2) (hereinafter also referred to as repeating unit d2).

Chem.

[0218] In formulas (d1) and (d2), R A is each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0219] In formula (d1), Y 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O-Y 11 - or *-C(=O)-NH-Y 11 -, and the phenylene group or naphthylene group may be substituted with a hydroxy group, a nitro group, a cyano group, an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom, or a halogen atom. Y 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. * represents a bond to a carbon atom of the main chain.

[0220] In formula (d2), Y 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond to a carbon atom of the main chain. R 31is a halogen atom, a cyano group, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. c is an integer from 0 to 4, preferably 0 or 1.

[0221] In formulas (d1) and (d2), AL 1 and AL 2 are each independently an acid-labile group. Specific examples of the acid-labile group include, but are not limited to, those described in JP-A-2013-80033 and JP-A-2013-83821.

[0222] Typically, specific examples of the acid-labile group include those represented by the following formulas (AL-1) to (AL-3). [Chemical formula] (In the formula, * represents a bond.)

[0223] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, an iodine atom or the like. The hydrocarbyl group may be linear, branched or cyclic. The hydrocarbyl group preferably has 1 to 20 carbon atoms.

[0224] In formula (AL-1), d is an integer from 0 to 10, preferably an integer from 1 to 5.

[0225] In formula (AL-2), R L3 and R L4is, independently of each other, a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, and an iodine atom. The hydrocarbyl group may be linear, branched, or cyclic. Also, R L2 、R L3 and R L4 Any two of them may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded or a carbon atom and an oxygen atom. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0226] In formula (AL-3), R L5 、R L6 and R L7 are, independently of each other, a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, and an iodine atom. The hydrocarbyl group may be linear, branched, or cyclic. Also, R L5 、R L6 and R L7 Any two of them may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0227] Specific examples of the repeating unit d1 include, but are not limited to, those shown below. In the following formulas, R A and AL 1 are the same as those described above.

Chemical formula

[0228]

Chemical formula

[0229]

Chemical formula

[0230]

Chem.

[0231]

Chem.

[0232]

Chem.

[0233]

Chem.

[0234] Specific examples of the repeating unit d2 include, but are not limited to, those shown below. In the following formulas, R A and AL 2 are the same as defined above.

Chem.

[0235]

Chem.

[0236]

Chem.

[0237] The polymer preferably further contains a repeating unit represented by the following formula (e1) (hereinafter also referred to as repeating unit e).

Chem.

[0238] In formula (e1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O-Z 11 - or *-C(=O)-NH-Z 11 -, and the phenylene group or naphthylene group may be substituted with a C1-C10 alkoxy group or a halogen atom which may contain a hydroxy group, a nitro group, a cyano group, or a fluorine atom. * represents a bond to a carbon atom of the main chain. Z 11 is a C1-C10 saturated hydrocarbylene group, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. R 41 is a hydrogen atom, or a group having 1 to 20 carbon atoms containing at least one or more structures selected from a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-O-C(=O)-).

[0239] Specific examples of the repeating unit e include, but are not limited to, those shown below. In the following formulas, R A is the same as described above.

Chemical formula

[0240]

Chemical formula

[0241]

Chemical formula

[0242]

Chemical formula

[0243]

Chemical formula

[0244]

Chem.

[0245]

Chem.

[0246]

Chem.

[0247]

Chem.

[0248]

Chem.

[0249]

Chem.

[0250]

Chem.

[0251]

Chem.

[0252]

Chem.

[0253]

Chem.

[0254] [Chemical formula]

[0255] As the repeating unit e, in ArF lithography, those having a lactone ring as a polar group are particularly preferred. In KrF lithography, EB lithography, and EUV lithography, those having a phenol moiety are preferred.

[0256] The polymer may further contain a repeating unit (hereinafter also referred to as repeating unit f) having a structure in which a hydroxy group is protected by an acid-labile group. The repeating unit f is not particularly limited as long as it has one or more structures in which a hydroxy group is protected and the protecting group is decomposed by the action of an acid to generate a hydroxy group, but those represented by the following formula (f1) are preferred. [Chemical formula]

[0257] In formula (f1), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 51 is a (e + 1)-valent hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom. R 52 is an acid-labile group. e is an integer of 1 to 4.

[0258] In formula (f1), the acid-labile group represented by R 52 may be any group that is deprotected by the action of an acid to generate a hydroxy group. The structure of R 52 is not particularly limited, but an acetal structure, a ketal structure, an alkoxycarbonyl group, an alkoxymethyl group represented by the following formula (f2), etc. are preferred, and an alkoxymethyl group represented by the following formula (f2) is particularly preferred. [Chemical formula] (In the formula, * represents a bond. R 53 is a hydrocarbyl group having 1 to 15 carbon atoms.)

[0259] R 52 Examples of the acid-labile group represented by 52 and the alkoxymethyl group represented by formula (f2) and the repeating unit e are the same as those exemplified in the description of the repeating unit d described in JP-A-2020-111564.

[0260] The polymer may further contain a repeating unit g derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene or a derivative thereof. Specific examples of the monomer that gives the repeating unit g include, but are not limited to, those shown below.

Chemical formula

[0261] The polymer may further contain a repeating unit h derived from styrene, indane, vinyl pyridine or vinyl carbazole.

[0262] In the polymer of the present invention, the content ratios of the repeating units a, b, c, d1, d2, e, f, g and h are preferably 0 < a ≤ 0.6, 0 < b ≤ 0.4, 0 ≤ c ≤ 0.8, 0 ≤ d1 ≤ 0.6, 0 ≤ d2 ≤ 0.6, 0 ≤ e ≤ 0.6, 0 ≤ f ≤ 0.3, 0 ≤ g ≤ 0.3 and 0 ≤ h ≤ 0.3, and more preferably 0 < a ≤ 0.5, 0 < b ≤ 0.3, 0 < c ≤ 0.7, 0 ≤ d1 ≤ 0.6, 0 ≤ d2 ≤ 0.5, 0 ≤ e ≤ 0.5, 0 ≤ f ≤ 0.2, 0 ≤ g ≤ 0.2 and 0 ≤ h ≤ 0.2. However, a + b + c + d1 + d2 + e + f + g + h ≤ 1.0.

[0263] The weight average molecular weight (Mw) of the polymer is preferably from 1,000 to 500,000, more preferably from 3,000 to 100,000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no risk of a decrease in resolution due to the inability to ensure the difference in dissolution rate before and after exposure. In the present invention, Mw is a polystyrene equivalent measurement value by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent.

[0264] Furthermore, as the pattern rule becomes finer, the influence of Mw / Mn tends to increase. Therefore, in order to obtain a resist composition suitably used for fine pattern dimensions, Mw / Mn is preferably narrowly dispersed in the range of 1.0 to 2.0. If it is within the above range, there is little risk of low molecular weight or high molecular weight polymers, and there is no risk of foreign matter being seen on the pattern or the pattern shape deteriorating after exposure.

[0265] Examples of the method for synthesizing the polymer include a method in which a monomer that provides the repeating unit described above is heated and polymerized by adding a radical polymerization initiator in an organic solvent.

[0266] Specific examples of the organic solvent used during polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), γ-butyrolactone (GBL), and the like. Specific examples of the polymerization initiator 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, lauroyl peroxide, and the like. The addition amount of these initiators is preferably 0.01 to 25 mol% based on the total of the 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, more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0267] The polymerization initiator may be added to the monomer solution and then supplied to the reaction kettle, or an initiator solution may be prepared separately from the monomer solution, and each may be independently supplied to the reaction kettle. Since there is a possibility that the polymerization reaction may proceed due to radicals generated from the initiator during the standby time and a superpolymer may be formed, from the viewpoint of quality control, it is preferable to prepare the monomer solution and the initiator solution independently and add them dropwise. The acid-labile group may be used as it is introduced into the monomer, or may be protected or partially protected after polymerization. Also, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used in combination for adjusting the molecular weight. In this case, the addition amount of these chain transfer agents is preferably 0.01 to 20 mol% based on the total of the monomers to be polymerized.

[0268] In the case of a monomer containing a hydroxy group, during polymerization, the hydroxy group may be replaced with an acetal group that is easily deprotected by an acid such as an ethoxyethoxy group, and then deprotected with a weak acid and water after polymerization, or may be replaced with an acetyl group, a formyl group, a pivaloyl group, etc., and then subjected to alkaline hydrolysis after polymerization.

[0269] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene and other monomers may be subjected to heat polymerization by adding a radical polymerization initiator in an organic solvent. However, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by alkali hydrolysis to obtain polyhydroxystyrene or hydroxypolyvinylnaphthalene.

[0270] Specific examples of the base during alkali hydrolysis include aqueous ammonia, triethylamine, etc. The reaction temperature is preferably -20 to 100 °C, more preferably 0 to 60 °C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0271] The amount of each monomer in the monomer solution may be appropriately set, for example, so as to achieve the preferred content ratio of the repeating units described above.

[0272] The polymer obtained by the above production method may use the reaction solution obtained by the polymerization reaction as the final product, or the polymerization solution may be added to a poor solvent, and the powder obtained through a purification process such as a reprecipitation method for obtaining a powder may be treated as the final product. However, from the viewpoints of working efficiency and quality stabilization, it is preferable to handle the polymer solution obtained by dissolving the powder obtained by the purification process in a solvent as the final product.

[0273] Specific examples of the solvent used in that case include ketones such as cyclohexanone and methyl-2-n-pentyl ketone described in paragraphs

[0144] to

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether (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, 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 alcohol solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0274] In the polymer solution, the concentration of the polymer is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass.

[0275] It is preferable to perform filter filtration on the reaction solution and the polymer solution. By performing filter filtration, foreign matters and gels that may cause defects can be removed, which is effective in terms of quality stabilization.

[0276] Examples of the material of the filter used for the filter filtration include those made of materials such as fluorocarbon-based, cellulose-based, nylon-based, polyester-based, and hydrocarbon-based materials. In the filtration step of the chemically amplified resist composition, a filter made of a fluorocarbon-based material such as so-called Teflon (registered trademark), a hydrocarbon-based material such as polyethylene or polypropylene, or nylon is preferred. The pore size of the filter can be appropriately selected according to the target cleanliness, but is preferably 100 nm or less, more preferably 20 nm or less. Also, these filters may be used alone or in combination of a plurality of filters. The filtration method may be such that the solution is passed only once, but it is more preferable to circulate the solution and perform filtration a plurality of times. The filtration step can be carried out in any order and number of times in the polymer production process, but it is preferable to filter the reaction solution, polymer solution, or both after the polymerization reaction.

[0277] [Chemically amplified resist composition] [(A) Base polymer] The chemically amplified resist composition of the present invention contains, as component (A), a base polymer containing the polymer described above.

[0278] The polymer may be used alone or in combination of two or more having different composition ratios, Mw and / or Mw / Mn. Further, the (A) base polymer may contain, in addition to the polymer, a hydrogenated product of a ring-opening metathesis polymer, and those described in JP-A-2003-66612 can be used for this.

[0279] [(B) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (B). In the present invention, the quencher is a material for preventing the diffusion to the unexposed portion by trapping the acid generated from the photoacid generator in the chemically amplified resist composition and forming a desired pattern.

[0280] (B) Specific examples of the quencher include onium salts represented by the following formula (1) or (2). [Chemical formula]

[0281] In formula (1), R q1 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, provided that the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is not substituted with a fluorine atom or a fluoroalkyl group. In formula (2), R q2 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom.

[0282] Specific examples of the hydrocarbyl group having 1 to 40 carbon atoms represented by R q1 include alkyl groups having 1 to 40 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decyl group, adamantyl group; aryl groups having 6 to 40 carbon atoms such as phenyl group, naphthyl group, anthracenyl group and the like. Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and the -CH 2- may be partially substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0283] R q2 Specific examples of the hydrocarbyl group represented by R q1 include, in addition to the substituents exemplified as specific examples of R

[0284] Specific examples of the anion of the onium salt represented by formula (1) include, but are not limited to, those shown below.

Chemical formula

[0285]

Chemical formula

[0286]

Chemical formula

[0287] Specific examples of the anion of the onium salt represented by formula (2) include, but are not limited to, those shown below.

Chemical formula

[0288]

Chemical formula

[0289] [Chemical formula]

[0290] In formulas (1) and (2), Mq + is an onium cation. As the onium cation, a sulfonium cation represented by the above-described formula (cation-1), an iodonium cation represented by the above-described formula (cation-2), or an ammonium cation represented by the following formula (cation-3) is preferable. [Chemical formula]

[0291] In formula (cation-3), R ct6 ~R ct9 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. Also, R ct6 and R ct7 may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded. Specific examples of the hydrocarbyl group are the same as those exemplified as the hydrocarbyl group represented by R ct1 ~R ct5 in the descriptions of formulas (cation-1) and (cation-2).

[0292] Specific examples of the ammonium cation represented by formula (cation-3) include, but are not limited to, those shown below. [Chemical formula]

[0293] Specific examples of the onium salt represented by formula (1) or (2) include any combination of the above-described anions and cations. These onium salts can be easily prepared by an ion exchange reaction using known organic chemical methods. For the ion exchange reaction, for example, JP-A-2007-145797 can be referred to.

[0294] The onium salt represented by formula (1) or (2) acts as a quencher in the chemically amplified resist composition of the present invention. This is due to each counter anion of the onium salt being a conjugate base of a weak acid. The weak acid referred to here means one that exhibits an acidity that cannot deprotect the acid-labile group of the acid-labile group-containing unit used in the base polymer. When the onium salt represented by formula (1) or (2) is used in combination with an onium salt type photoacid generator having a conjugate base of a strong acid such as a sulfonic acid with the α-position fluorinated as a counter anion, it functions as a quencher. That is, when an onium salt that generates a strong acid such as a sulfonic acid with the α-position fluorinated and an onium salt that generates a weak acid such as a non-fluorinated sulfonic acid or a carboxylic acid are mixed and used, when the strong acid generated from the photoacid generator by high-energy ray irradiation collides with the onium salt having an unreacted weak acid anion, a weak acid is released by salt exchange, and an onium salt having a strong acid anion is generated. Since the strong acid is exchanged for a weak acid with lower catalytic ability in this process, apparently, the acid is deactivated and the acid diffusion can be controlled.

[0295] Also, as the (B) quencher, an onium salt having a sulfonium cation and a phenoxide anion site in the same molecule described in Japanese Patent No. 6848776, and further an onium salt having a sulfonium cation and a carboxylate anion site in the same molecule described in Japanese Patent No. 6583136 and Japanese Unexamined Patent Application Publication No. 2020-200311, and an onium salt having an iodonium cation and a carboxylate anion site in the same molecule described in Japanese Patent No. 6274755 can also be used.

[0296] Here, when the photoacid generator that generates a strong acid is an onium salt, as described above, the strong acid generated by high-energy ray irradiation can be exchanged for a weak acid. On the other hand, it is considered that the weak acid generated by high-energy ray irradiation hardly collides with the onium salt that generates an unreacted strong acid to perform salt exchange. This is due to the phenomenon that the onium cation easily forms an ion pair with the anion of a stronger acid.

[0297] When the chemically amplified resist composition of the present invention contains an onium salt represented by formula (1) or (2) as (B) a quencher, its content is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, based on 80 parts by mass of (A) the base polymer. If the onium salt type quencher of component (B) is within the above range, the resolution is good and the sensitivity does not decrease significantly, which is preferable. The onium salt represented by formula (1) or (2) may be used alone or in combination of two or more.

[0298] The chemically amplified resist composition of the present invention may contain a nitrogen-containing compound as (B) a quencher. Examples of the nitrogen-containing compound of component (B) include primary, secondary or tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond. Also, compounds in which a primary or secondary amine is protected with a carbamate group, such as those described in Japanese Patent No. 3790649, can be mentioned. Further, compounds having an acid-labile group in the molecule, as described in JP-A-2009-109595, can be mentioned.

[0299] Also, a sulfonium salt of sulfonic acid having a nitrogen-containing substituent may be used as the nitrogen-containing compound. Such a compound functions as a quencher in the unexposed area and loses its quenching ability by neutralization with its own generated acid in the exposed area, functioning as a so-called photo-disintegrating base. By using a photo-disintegrating base, the contrast between the exposed area and the unexposed area can be further enhanced. For photo-disintegrating bases, for example, JP-A-2009-109595, JP-A-2012-46501, etc. can be referred to.

[0300] When the chemically amplified resist composition of the present invention contains a nitrogen-containing compound as (B) a quencher, its content is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, based on 80 parts by mass of (A) the base polymer. The nitrogen-containing compound may be used alone or in combination of two or more.

[0301] [(C) Organic solvent] The chemically amplified resist composition of the present invention may contain an organic solvent as the (C) component. The (C) organic solvent is not particularly limited as long as it can dissolve each of the above-described components and each of the components described below. Specific examples of such organic solvents include ketones such as cyclopentanone, cyclohexanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ketoalcohols such as 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, 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; and mixed solvents thereof.

[0302] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, DAA, and mixed solvents thereof, which have particularly excellent solubility of the base polymer of the (A) component, are preferred.

[0303] In the chemically amplified resist composition of the present invention, the content of the (C) organic solvent is preferably 200 to 5000 parts by mass, more preferably 400 to 3500 parts by mass, based on 80 parts by mass of the (A) base polymer. The (C) organic solvent may be used alone or in combination of two or more.

[0304] [(D) Acid generator] The chemically amplified resist composition of the present invention may contain an acid generator as long as the effects of the present invention are not impaired. Examples of the acid generator include compounds (photoacid generators) that generate an acid upon exposure to actinic rays or radiation. The photoacid generator is not particularly limited as long as it is a compound that generates an acid upon irradiation with high-energy rays, but those that generate sulfonic acid, imidic acid or methidic acid are preferred. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like. Specific examples of the acid generator include those described in paragraphs

[0122] to

[0142] of JP-A-2008-111103.

[0305] Also, as the photoacid generator, a sulfonium salt represented by the following formula (3-1) or an iodonium salt represented by the following formula (3-2) can be preferably used. [Chemical formula]

[0306] In formulas (4-1) and (4-2), R 101 ~R 105 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. Specific examples of the halogen atom and the hydrocarbyl group are R ct1 ~R ct5Examples of the halogen atom and the hydrocarbyl group represented by the formula include those similar to those exemplified above. Also, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of -CH 2 - of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. Also, R 101 and R 102 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. Specific examples of the ring formed at this time include those similar to the rings that can be formed by R ct1 and R ct2 being bonded to each other to form a ring together with the sulfur atom to which they are bonded, as exemplified in the description of formula (cation-1).

[0307] Specific examples of the cation of the sulfonium salt represented by formula (3-1) include those similar to the sulfonium cation represented by formula (cation-1). Also, specific examples of the cation of the iodonium salt represented by formula (4-2) include those similar to the iodonium cation represented by formula (cation-2).

[0308] In formulas (3-1) and (3-2), Xa - is an anion selected from the following formulas (3A) to (3D).

Chemical formula

[0309] In formula (3A), R fais a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include those exemplified in the description of R in the following formula (3A'). fa1 are the same as those exemplified in the description of fa1 .

[0310] As the anion represented by the formula (3A), those represented by the following formula (3A') are preferable. [Chemical formula]

[0311] In the formula (3A'), R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group.

[0312] In the formula (3A'), R fa1 is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a heteroatom. As the heteroatom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, etc. are preferable, and an oxygen atom is more preferable. As the hydrocarbyl group, those having 6 to 30 carbon atoms are particularly preferable from the viewpoint of obtaining high resolution in fine pattern formation.

[0313] R fa1The hydrocarbyl 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 38 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2-ethylhexyl group, nonyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosyl group; cyclic saturated hydrocarbyl groups having 3 to 38 carbon atoms such as cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbornylmethyl group, tricyclodecyl group, tetracyclododecyl group, tetracyclododecylmethyl group, dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms such as allyl group, 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms such as phenyl group, 1-naphthyl group, 2-naphthyl group; aralkyl groups having 7 to 38 carbon atoms such as benzyl group, diphenylmethyl group; groups obtained by combining these, and the like.

[0314] In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc. The -CH of the hydrocarbyl group 2- may be partially substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. The heteroatom is preferably an oxygen atom. Specific examples of the hydrocarbyl group containing a heteroatom include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, a 3-oxocyclohexyl group, etc.

[0315] Regarding the synthesis of the sulfonium salt containing the anion represented by the formula (3A'), it is detailed in JP-A-2007-145797, JP-A-2008-106045, JP-A-2009-7327, JP-A-2009-258695, etc. Further, the sulfonium salts described in JP-A-2010-215608, JP-A-2012-41320, JP-A-2012-106986, JP-A-2012-153644, etc. are also preferably used.

[0316] Specific examples of the anion represented by the formula (3A) include, but are not limited to, those shown below. In the following formulas, Ac is an acetyl group.

Chemical formula

[0317]

Chemical formula

[0318]

Chemical formula

[0319]

Chem.

[0320] In formula (3B), R fb1 and R fb2 are each independently a fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include those similar to the hydrocarbyl group exemplified as R fa1 in formula (3A'). Preferably, R fb1 and R fb2 are a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Further, R fb1 and R fb2 may be bonded to each other to form a ring together with the group (-CF 2 -SO 2 -N - -SO 2 -CF 2 -) to which they are bonded. At this time, the group obtained by bonding R fb1 and R fb2 to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0321] In formula (3C), R fc1 , R fc2 and R fc3 are each independently a fluorine atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include those similar to the hydrocarbyl group exemplified as R fa1 in formula (3A'). Preferably, R fc1 , R fc2 and R fc3 are a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Further, R fc1 and R fc2which may combine with each other to form a ring together with the group (-CF 2 -SO 2 -C - -SO 2 -CF 2 -), and at this time, the group obtained by combining R fc1 and R fc2 with each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0322] In formula (3D), R fd is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include the same ones as those exemplified as the hydrocarbyl group represented by R fa1 in formula (3A').

[0323] Regarding the synthesis of the sulfonium salt containing the anion represented by formula (3D), it is detailed in JP-A-2010-215608 and JP-A-2014-133723.

[0324] Specific examples of the anion represented by formula (3D) include, but are not limited to, the following.

Chemical formula

[0325]

Chemical formula

[0326] Note that the photoacid generator containing the anion represented by formula (3D) does not have a fluorine atom at the α-position of the sulfo group, but has two trifluoromethyl groups at the β-position, and thus has sufficient acidity to cleave the acid-labile group in the base polymer. Therefore, it can be used as a photoacid generator.

[0327] As the photoacid generator, those represented by the following formula (4) can also be preferably used. [Chemical formula]

[0328] In formula (4), R 201 and R 202 are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. R 203 is a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. Further, any two of R 201 , R 202 and R 203 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. At this time, specific examples of the ring include those similar to the rings that can be formed by R ct1 and R ct2 being bonded to each other to form a ring together with the sulfur atom to which they are bonded, as exemplified in the description of formula (cation-1).

[0329] The hydrocarbyl group having 1 to 30 carbon atoms represented by R 201 and R 202 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 group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group; cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, oxanorbornyl group, tricyclo[5.2.1.0 2,6Cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms such as decyl group and adamantyl group; aryl groups having 6 to 30 carbon atoms such as phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, naphthyl group, methylnaphthyl group, ethylnaphthyl group, n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group, anthracenyl group; groups obtained by combining these, etc. may be mentioned. Further, part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and part of -CH 2 - of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0330] R 203The hydrocarbylene 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 alkanediyl groups having 1 to 30 carbon atoms such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group; cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group; arylene groups having 6 to 30 carbon atoms such as phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, tert-butylnaphthylene group; groups obtained by combining these, and the like. Further, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of -CH 2 - of the hydrocarbylene group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, it may contain a hydroxy 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. As the hetero atom, an oxygen atom is preferable.

[0331] In formula (4), L A is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond, an ether bond, or a hetero atom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those similar to the hydrocarbylene groups exemplified as the R 203 -represented hydrocarbylene groups.

[0332] In formula (4), X A , X B , X C and X D are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. However, at least one of X A , X B , X C and X D is a fluorine atom or a trifluoromethyl group.

[0333] In formula (4), k is an integer from 0 to 3.

[0334] As the photoacid generator represented by formula (4), those represented by the following formula (4') are preferable.

Chemical formula

[0335] In formula (4'), L A is the same as above. R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R 301 , R 302 and R 303 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those similar to the hydrocarbyl groups exemplified as the R fa1 -represented hydrocarbyl groups in formula (3A'). x and y are each independently an integer from 0 to 5. z is an integer from 0 to 4.

[0336] Specific examples of the photoacid generator represented by formula (4) include those similar to the ones exemplified as the photoacid generator represented by formula (2) in JP-A-2017-26980.

[0337] Among the photoacid generators, those containing an anion represented by formula (3A') or (3D) are particularly preferred because they have low acid diffusion and excellent solubility in solvents. Also, those represented by formula (4') are particularly preferred because they have extremely low acid diffusion.

[0338] As other acid generators, sulfonium salts and iodonium salts containing an anion having an aromatic ring substituted with an iodine atom and represented by the following formula (5-1) or (5-2) can also be used.

Chemical formula

[0339] In formulas (5-1) and (5-2), p is 1, 2, or 3. q and r are integers satisfying 1 ≤ q ≤ 5, 0 ≤ r ≤ 3, and 1 ≤ q + r ≤ 5. q is preferably 1, 2, or 3, more preferably 2 or 3. r is preferably 0, 1, or 2.

[0340] In formulas (5-1) and (5-2), L 1 is a single bond, an ether bond, an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched, or cyclic.

[0341] In formulas (5-1) and (5-2), L 2 is a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and a (p + 1)-valent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0342] In formulas (5-1) and (5-2), R 401is a C1-C20 hydrocarbyl group, a C1-C20 hydrocarbyloxy group, a C2-C20 hydrocarbylcarbonyl group, a C2-C20 hydrocarbyloxycarbonyl group, a C2-C20 hydrocarbylcarbonyloxy group or a C1-C20 hydrocarbylsulfonyloxy group, which may contain a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond, or -N(R 401A )(R 401B ), -N(R 401C )-C(=O)-R 401D or -N(R 401C )-C(=O)-O-R 401D . R 401A and R 401B are each independently a hydrogen atom or a C1-C6 saturated hydrocarbyl group. R 401C is a hydrogen atom or a C1-C6 saturated hydrocarbyl group, which may contain a halogen atom, a hydroxy group, a C1-C6 saturated hydrocarbyloxy group, a C2-C6 saturated hydrocarbylcarbonyl group or a C2-C6 saturated hydrocarbylcarbonyloxy group. R 401D is a C1-C16 aliphatic hydrocarbyl group, a C6-C14 aryl group or a C7-C15 aralkyl group, which may contain a halogen atom, a hydroxy group, a C1-C6 saturated hydrocarbyloxy group, a C2-C6 saturated hydrocarbylcarbonyl group or a C2-C6 saturated hydrocarbylcarbonyloxy group. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group and hydrocarbylsulfonyloxy group may be linear, branched or cyclic. When p and / or r is 2 or more, each R 401 may be the same as or different from each other.

[0343] Among these, R 401Examples thereof include a hydroxy group, -N(R 401C )-C(=O)-R 401D , -N(R 401C )-C(=O)-O-R 401D , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group and the like are preferable.

[0344] In formulas (5-1) and (5-2), Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, and at least one of these is a fluorine atom or a trifluoromethyl group. Further, Rf 1 and Rf 2 may combine to form a carbonyl group. In particular, it is preferable that both Rf 3 and Rf 4 are fluorine atoms.

[0345] In formulas (5-1) and (5-2), R 402 ~R 406 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include those similar to the hydrocarbyl groups exemplified as R ct1 ~R ct5 in the description of formulas (cation-1) and (cation-2). Further, part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone ring, a sulfo group or a sulfonium salt-containing group, and part of -CH 2 - of the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond or a sulfonic acid ester bond. Further, R 402 and R 403 may combine with each other to form a ring together with the sulfur atom to which they are attached. At this time, specific examples of the ring include those of R ct1 and R ct2 in the description of formula (cation-1).Those that can be formed by combining with each other and together with the sulfur atoms to which they are attached are exemplified by the same ones as those exemplified as the rings that can be formed.

[0346] Specific examples of the cation of the sulfonium salt represented by formula (5-1) include the same ones as those exemplified as the sulfonium cation represented by formula (cation-1). Further, specific examples of the cation of the iodonium salt represented by formula (5-2) include the same ones as those exemplified as the iodonium cation represented by formula (cation-2).

[0347] Specific examples of the anion of the onium salt represented by formula (5-1) or (5-2) include, but are not limited to, those shown below.

Chemical formula

[0348]

Chemical formula

[0349]

Chemical formula

[0350]

Chemical formula

[0351]

Chemical formula

[0352]

Chemical formula

[0353]

Chemical formula

[0354]

Chem.

[0355]

Chem.

[0356]

Chem.

[0357]

Chem.

[0358]

Chem.

[0359]

Chem.

[0360]

Chem.

[0361]

Chem.

[0362]

Chem.

[0363]

Chem.

[0364]

Chem.

[0365]

Chem.

[0366]

Chem.

[0367]

Chem.

[0368]

Chem.

[0369] When the chemically amplified resist composition of the present invention contains a (D) acid generator, its content is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, based on 80 parts by mass of the (A) base polymer. When the addition amount of the acid generator of the component (D) is within the above range, the resolution is good, and there is no risk of foreign matter problems during development or peeling of the resist film, which is preferable. The (D) acid generator may be used alone or in combination of two or more.

[0370] [(E) Surfactant] The chemically amplified resist composition of the present invention may further contain a surfactant as the (E) component. As the (E) surfactant, preferably a surfactant that is insoluble or hardly soluble in water and soluble in an alkaline developer, or a surfactant that is insoluble or hardly soluble in water and an alkaline developer. As such surfactants, those described in JP-A-2010-215608 and JP-A-2011-16746 can be referred to.

[0371] Examples of surfactants that are insoluble or poorly soluble in water and alkaline developers include, among the surfactants described in the above publication, FC-4430 (manufactured by 3M), Surflon (registered trademark) S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Orfin (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and oxetane ring-opening polymers represented by the following formula (surf-1), etc. are preferable.

Chem.

[0372] Here, regardless of the above description, R, Rf, A, B, C, m, and n are only applicable to formula (surf-1). R is an aliphatic group having 2 to 4 valences and 2 to 5 carbon atoms. Examples of the aliphatic group include, as a divalent group, an ethylene group, a 1,4-butylene group, a 1,2-propylene group, a 2,2-dimethyl-1,3-propylene group, a 1,5-pentylene group, etc., and examples of the trivalent or tetravalent group include the following.

Chem.

[0373] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, etc. are preferable.

[0374] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer of 0 to 3, n is an integer of 1 to 4, and the sum of n and m is the valence of R, which is an integer of 2 to 4. A is 1. B is an integer of 2 to 25, preferably an integer of 4 to 20. C is an integer of 0 to 10, preferably 0 or 1. Further, each structural unit in the formula (surf-1) does not define its order, and they may be block-bonded or randomly-bonded. Regarding the production of the surfactant of the partially fluorinated oxetane ring-opening polymer system, it is detailed in, for example, US Patent No. 5650483.

[0375] A surfactant that is insoluble or hardly soluble in water and soluble in an alkaline developer has a function of reducing water penetration and leaching by orienting on the surface of the resist film when no resist protective film is used in ArF immersion lithography. Therefore, it is useful for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure apparatus. Also, it is soluble during development with an alkaline aqueous solution after exposure or post-exposure bake (PEB), and it is less likely to become foreign matter that causes defects, so it is useful. Such a surfactant has the property of being insoluble or hardly soluble in water and soluble in an alkaline developer, and is a polymer-type surfactant, also called a hydrophobic resin. Particularly, those with high water repellency and improved lubricity are preferred.

[0376] Specific examples of such polymer-type surfactants include those containing at least one selected from the repeating units represented by the following formulas (6A) to (6E).

Chemical formula

[0377] In formulas (6A) to (6E), R B is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. W 1 is -CH 2 -, -CH 2 CH 2 -, -O-, or two separated -H's. Rs1 is, independently of each other, a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. R s2 is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. R s3 is, independently of each other, a hydrogen atom, a hydrocarbyl group or fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid-labile group. R s3 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. R s4 is a (u + 1)-valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer of 1 to 3. R s5 is, independently of each other, a hydrogen atom or a group represented by -C(=O)-O-R sa R sa is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. R s6 is a hydrocarbyl group or fluorinated hydrocarbyl group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be interposed between carbon-carbon bonds thereof.

[0378] R s1 The hydrocarbyl group having 1 to 10 carbon atoms represented by R is preferably a saturated hydrocarbyl group, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group. Among these, those having 1 to 6 carbon atoms are preferred.

[0379] R s2The hydrocarbylene group represented by is preferably a saturated hydrocarbylene group, and may be linear, branched or cyclic. Specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group and the like.

[0380] R s3 or R s6 The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include saturated hydrocarbyl groups, aliphatic unsaturated hydrocarbyl groups such as alkenyl groups and alkynyl groups, etc., but saturated hydrocarbyl groups are preferred. Specific examples of the saturated hydrocarbyl group include those exemplified as the hydrocarbyl group represented by R s1 In addition to those exemplified as the hydrocarbyl group represented by , undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and the like are included. R s3 or R s6 Specific examples of the fluorinated hydrocarbyl group represented by include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbyl group are substituted with fluorine atoms. As described above, an ether bond or a carbonyl group may be interposed between these carbon-carbon bonds.

[0381] R s3 Specific examples of the acid-labile group represented by include groups represented by the aforementioned formulas (AL-3) to (AL-5), a trialkylsilyl group in which each alkyl group is an alkyl group having 1 to 6 carbon atoms, an oxo group-containing alkyl group having 4 to 20 carbon atoms, and the like.

[0382] 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 eliminating u hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group and the like.

[0383] R saAs the fluorinated hydrocarbyl group represented by [the formula], a saturated one is preferred, and it may be linear, branched, or cyclic. Specific examples thereof include those in which some or all of the hydrogen atoms of the hydrocarbyl group are substituted with fluorine atoms. Specific examples thereof include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3,3,3-trifluoro-1-propyl group, a 3,3,3-trifluoro-2-propyl group, a 2,2,3,3-tetrafluoropropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, a 2,2,3,3,4,4,4-heptafluorobutyl group, a 2,2,3,3,4,4,5,5-octafluoropentyl group, a 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, a 2-(perfluorobutyl)ethyl group, a 2-(perfluorohexyl)ethyl group, a 2-(perfluorooctyl)ethyl group, a 2-(perfluorodecyl)ethyl group, and the like.

[0384] Specific examples of the repeating unit represented by any of the formulas (6A) to (6E) include, but are not limited to, those shown below. In the following formulas, R B is the same as described above.

Chemical formula

[0385]

Chemical formula

[0386]

Chemical formula

[0387]

Chemical formula

[0388]

Chemical formula

[0389] The polymer surfactant may further contain other repeating units other than the repeating units represented by the formulas (6A) to (6E). Specific examples of the other repeating units include repeating units obtained from methacrylic acid, α-trifluoromethylacrylic acid derivatives, and the like. In the polymer surfactant, the content of the repeating units represented by the formulas (6A) to (6E) is preferably 20 mol% or more, more preferably 60 mol% or more, and still more preferably 100 mol% in all the repeating units.

[0390] The Mw of the polymer surfactant is preferably from 1,000 to 500,000, more preferably from 3,000 to 100,000. The Mw / Mn is preferably from 1.0 to 2.0, more preferably from 1.0 to 1.6.

[0391] As a method for synthesizing the polymer surfactant, a method of heating and polymerizing a monomer containing an unsaturated bond that gives repeating units represented by the formulas (6A) to (6E) and, if necessary, other repeating units in an organic solvent by adding a radical initiator can be mentioned. Specific examples of the organic solvent used during the polymerization include toluene, benzene, THF, diethyl ether, dioxane, and the like. Specific examples of the polymerization initiator include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide, and the like. The reaction temperature is preferably from 50 to 100°C. The reaction time is preferably from 4 to 24 hours. The acid-labile group may be used as it is introduced into the monomer, or may be protected or partially protected after polymerization.

[0392] When synthesizing the polymer surfactant, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol may be used to adjust the molecular weight. In that case, the addition amount of these chain transfer agents is preferably from 0.01 to 10 mol% based on the total number of moles of the monomers to be polymerized.

[0393] When the chemically amplified resist composition of the present invention contains (E) a surfactant, its content is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, based on 80 parts by mass of the (A) base polymer. When the content of the (E) surfactant is 0.1 part by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved. When it is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is small, and the height of the formed fine pattern is sufficiently maintained. The (E) surfactant may be used alone or in combination of two or more.

[0394] [(F) Dissolution inhibitor] The chemically amplified resist composition of the present invention may further contain a dissolution inhibitor as the (F) component. When the chemically amplified resist composition of the present invention is positive, by blending a dissolution inhibitor, the difference in dissolution rate between the exposed part and the unexposed part can be further increased, and the resolution can be further improved.

[0395] Specific examples of the dissolution inhibitor include compounds having a molecular weight preferably of 100 to 1000, more preferably 150 to 800, and containing two or more phenolic hydroxy groups in the molecule, and the hydrogen atoms of the phenolic hydroxy groups are substituted by acid-labile groups in a proportion of 0 to 100 mol% as a whole, or compounds having a carboxy group in the molecule, and the hydrogen atoms of the carboxy groups are substituted by acid-labile groups in a proportion of 50 to 100 mol% on average as a whole. Specifically, bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalene carboxylic acid, adamantane carboxylic acid, compounds in which the hydrogen atoms of the hydroxy groups and carboxy groups of cholic acid are substituted by acid-labile groups, etc. are included. For example, those described in paragraphs

[0155] to

[0178] of JP-A-2008-122932 are included.

[0396] When the chemically amplified resist composition of the present invention contains (F) a dissolution inhibitor, its content is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass, based on 80 parts by mass of the (A) base polymer. The (F) dissolution inhibitor may be used alone or in combination of two or more.

[0397] [(G) Other components] The chemically amplified resist composition of the present invention may contain, as (G) other components, a compound that decomposes by an acid to generate an acid (acid-proliferating compound), an organic acid derivative, a fluorine-substituted alcohol, a water-repellency improver, etc. As the acid-proliferating compound, reference can be made to the compounds described in JP-A-2009-269953 or JP-A-2010-215608. When the acid-proliferating compound is contained, its content is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, based on 80 parts by mass of the (A) base polymer. If the content is too large, it is difficult to control acid diffusion, and deterioration of resolution and pattern shape may occur. As the organic acid derivative and the fluorine-substituted alcohol, reference can be made to the compounds described in JP-A-2009-269953 or JP-A-2010-215608.

[0398] The water-repellency improver can be used in immersion lithography without using a top coat. As the water-repellency improver, a polymer containing an alkyl fluoride group, a polymer containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue having a specific structure, etc. are preferable, and those exemplified in JP-A-2007-297590, JP-A-2008-111103, etc. are more preferable. The water-repellency improver needs to be soluble in an alkaline developer or an organic solvent developer. The water-repellency improver having the above-described specific 1,1,1,3,3,3-hexafluoro-2-propanol residue has good solubility in the developer. As the water-repellency improver, a polymer containing a repeating unit containing an amino group or an amine salt has a high effect of preventing evaporation of the acid in PEB and preventing the opening defect of the hole pattern after development. When the chemically amplified resist composition of the present invention contains the water-repellency improver, its content is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, based on 80 parts by mass of the (A) base polymer.

[0399] [Pattern formation method] When the chemically amplified resist composition of the present invention is used for various integrated circuit manufacturing, known lithography techniques can be applied. For example, as a pattern formation method, a method including a step of forming a resist film on a substrate using the above-described chemically amplified resist composition, a step of exposing the resist film with high-energy rays, and a step of developing the exposed resist film using a developer can be mentioned.

[0400] First, the chemically amplified resist composition of the present invention is applied onto a substrate for integrated circuit manufacturing (Si, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi 2 , SiO 2 , etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc. so that the coating film thickness becomes 0.01 to 2.0 μm. This is prebaked on a hot plate, preferably at 60 to 150 °C for 10 seconds to 30 minutes, more preferably at 80 to 120 °C for 30 seconds to 20 minutes, to form a resist film.

[0401] Next, the resist film is exposed using high-energy rays. Examples of the high-energy rays include ultraviolet rays, far ultraviolet rays, EB, EUV with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. When using ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, γ-rays, synchrotron radiation, etc. as the high-energy rays, the exposure amount is preferably about 1 to 200 mJ / cm 2 , more preferably about 10 to 100 mJ / cm 2 , and irradiation is performed so as to be in this range. When using EB as the high-energy rays, the exposure amount is preferably about 0.1 to 100 μC / cm 2 , more preferably about 0.5 to 50 μC / cm 2It is drawn so as to reach a certain level, directly or using a mask for forming a target pattern. The chemically amplified resist composition of the present invention is particularly suitable for fine patterning by ArF excimer laser light with a wavelength of 193 nm, KrF excimer laser light with a wavelength of 248 nm, EB, or EUV, X-rays, soft X-rays, γ-rays, or synchrotron radiation among high-energy rays.

[0402] After exposure, PEB may be performed on a hot plate, preferably at 60 to 150 °C for 10 seconds to 30 minutes, more preferably at 80 to 120 °C for 30 seconds to 20 minutes.

[0403] After exposure or after PEB, an alkaline aqueous solution developer such as 0.1 to 10% by mass, preferably 2 to 5% by mass of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. is used, and development is carried out by a conventional method such as the dip method, puddle method, spray method, etc. for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes. Thus, the irradiated part is dissolved in the developer, and the unexposed part is not dissolved, and a target positive pattern is formed on the substrate.

[0404] A negative pattern can also be obtained by using an organic solvent developer instead of the alkaline aqueous solution. Specific examples of the developer used at this time include 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, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more.

[0405] At the end of development, rinsing may be performed. As the rinse liquid, a solvent that is miscible with the developer and does not dissolve the resist film is preferred. As such a solvent, alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms are preferably used.

[0406] Specific examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol and the like.

[0407] Specific examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, di-n-hexyl ether and the like.

[0408] Specific examples of the alkane having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane and the like. Specific examples of the alkene having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene and the like. Specific examples of the alkyne having 6 to 12 carbon atoms include hexyne, heptyne, octyne and the like.

[0409] Specific examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, mesitylene, and the like.

[0410] By performing rinsing, it is possible to reduce the collapse of the resist pattern and the occurrence of defects. Also, rinsing is not necessarily essential, and the amount of solvent used can be reduced by not performing rinsing.

[0411] The developed hole pattern or trench pattern can also be shrunk by thermal flow, RELACS technology, or DSA technology. A shrink agent is applied onto the hole pattern, and crosslinking of the shrink agent occurs on the surface of the resist film due to the diffusion of the acid catalyst from the resist film during baking, and the shrink agent adheres to the sidewall of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds, removing the excess shrink agent and shrinking the hole pattern.

Examples

[0412] Hereinafter, the present invention will be specifically described by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0413] [1] Synthesis of base polymer The monomers used for the synthesis of the base polymer are as follows.

Chemical formula

[0414]

Chemical formula

[0415]

Chemical formula

[0416] [Chemical formula]

[0417] [Chemical formula]

[0418] [Chemical formula]

[0419] [Example 1-1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, into a flask, 54.3 g of monomer a-1, 26.2 g of monomer b-1, 19.5 g of monomer c-1, 3.74 g of V-601 (manufactured by Fuji Film Wako Pure Chemical Corporation) and 139 g of MEK were taken to prepare a monomer-polymerization initiator solution. 46 g of MEK was taken into another flask under a nitrogen atmosphere, heated to 80 °C with stirring, and then the monomer-polymerization initiator solution was added dropwise over 4 hours. After the addition was completed, stirring was continued for 2 hours while maintaining the temperature of the polymerization solution at 80 °C, and then it was cooled to room temperature. The obtained polymerization solution was added dropwise to 3000 g of vigorously stirred hexane, and the precipitated polymer was separated by filtration. The obtained polymer was washed twice with 600 g of hexane and then vacuum dried at 50 °C for 20 hours to obtain a white powdery polymer P-1 (yield 97.1 g, yield 97%). The Mw of polymer P-1 was 7500, and Mw / Mn was 1.69. Note that Mw is the polystyrene conversion measurement value by GPC using DMF as a solvent. [Chemical formula]

[0420] [Examples 1-2 to 1-25, Comparative Examples 1-1 to 1-15] Synthesis of Polymers P-2 to P-25, Comparative Polymers CP-1 to CP-15 The polymers shown in Tables 1 and 2 were produced in the same manner as in Example 1-1, except that the types and mixing ratios of the respective monomers were changed. Note that in Tables 1 and 2, the numerical values in parentheses represent the introduction ratios (mol%) of each repeating unit.

[0421]

Table 1

[0422]

Table 2

[0423] [3] Preparation of resist composition [Examples 2-1 to 2-25, Comparative Examples 2-1 to 2-15] Predetermined components selected from the base polymers (P-1 to P-25) of the present invention, comparative base polymers (CP-1 to CP-15), acid generators (PAG-1, PAG-2), and quenchers (SQ-1 to SQ-3, AQ-1) were dissolved in a solvent containing 0.01% by mass of FC-4430 manufactured by 3M as a surfactant with the compositions shown in Tables 3 and 4 below to prepare a solution, and the solution was filtered through a 0.2 μm Teflon (registered trademark) type filter to prepare chemically amplified resist compositions (R-1 to R-25, CR-1 to CR-15).

[0424]

Table 3

[0425]

Table 4

[0426] In Tables 3 and 4, the solvent, quenchers (SQ-1 to SQ-3, AQ-1), and acid generators (PAG-1, PAG-2) are as follows. · Solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (diacetone alcohol)

[0427] · Quenchers: SQ-1 to SQ-3, AQ-1

Chemical formula

[0428] · Acid generator: PAG-1, PAG-2

Chem.

[0429] [4] EUV Lithography Evaluation (1) [Examples 3-1 to 3-25, Comparative Examples 3-1 to 3-15] Each chemically amplified resist composition (R-1 to R-25, CR-1 to CR-15) shown in Tables 3 and 4 was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. was formed to a film thickness of 20 nm, and pre-baked at 100 °C for 60 seconds using a hot plate to prepare a resist film with a film thickness of 50 nm. For the said resist film, exposure of an LS pattern with a dimension of 18 nm and a pitch of 36 nm on the wafer was performed using an EUV scanner NXE3300 (NA 0.33, σ 0.9 / 0.6, dipole illumination) manufactured by ASML while changing the exposure dose and focus (exposure dose pitch: 1 mJ / cm 2 , focus pitch: 0.020 μm). After exposure, PEB was performed at the temperatures shown in Tables 4 and 5 for 60 seconds. Then, paddle development was performed for 30 seconds with a 2.38% by mass TMAH aqueous solution, rinsing was performed with a surfactant-containing rinsing material, spin drying was performed, and a positive pattern was obtained. The obtained LS pattern was observed with a length measuring SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, and sensitivity, EL, LWR, DOF, and collapse limit were evaluated according to the following methods. The results are shown in Tables 5 and 6.

[0430] [Sensitivity Evaluation] The optimum exposure dose Eop (mJ / cm 2 ) at which an LS pattern with a line width of 18 nm and a pitch of 36 nm was obtained was determined and taken as the sensitivity. The smaller this value, the higher the sensitivity.

[0431] [EL Evaluation] EL (%) was obtained from the exposure dose formed within the range of ±10% (16.2 to 19.8 nm) of the 18-nm space width in the LS pattern by the following equation. The larger this value, the better the performance. EL (%) = (|E 1 - E 2 | / Eop) × 100 E 1 : Optimal exposure dose that gives an LS pattern with a line width of 16.2 nm and a pitch of 36 nm E 2 : Optimal exposure dose that gives an LS pattern with a line width of 19.8 nm and a pitch of 36 nm Eop: Optimal exposure dose that gives an LS pattern with a line width of 18 nm and a pitch of 36 nm

[0432] [LWR Evaluation] The LS pattern obtained by irradiating with Eop was measured for the dimensions at 10 locations in the longitudinal direction of the line, and three times the standard deviation (σ) (3σ) was determined as the LWR from the results. The smaller this value, the smaller the roughness and the more uniform the line width pattern can be obtained.

[0433] [DOF Evaluation] As the focus depth evaluation, the focus range formed within the range of ±10% (16.2 to 19.8 nm) of the 18-nm dimension in the LS pattern was determined. The larger this value, the wider the focus depth.

[0434] [Evaluation of the Collapse Limit of the Line Pattern] The line dimensions of each exposure dose at the optimal focus of the LS pattern were measured at 10 locations in the longitudinal direction. The thinnest line dimension obtained without collapse was taken as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0435] [Table 5]

[0436] [Table 6]

[0437] From the results shown in Tables 5 and 6, it was found that the chemically amplified resist composition using the polymer of the present invention has good sensitivity and is excellent in EL, LWR, and DOF. In addition, the value of the collapse limit was small, and it was confirmed that the pattern was resistant to collapse even in fine pattern formation. Therefore, it was shown that the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography.

[0438] [5] EUV Lithography Evaluation (2) [Examples 4-1 to 4-25, Comparative Examples 4-1 to 4-15] Each of the chemically amplified resist compositions (R-1 to R-25, CR-1 to CR-15) shown in Tables 3 and 4 was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. was formed to a film thickness of 20 nm, and pre-baked at 105 °C for 60 seconds using a hot plate to prepare a resist film with a film thickness of 50 nm. This was exposed using an EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a hole pattern having a wafer-level dimension of pitch 46 nm and +20% bias) manufactured by ASML, and PEB was performed at the temperatures described in Tables 7 and 8 for 60 seconds using a hot plate, and development was carried out for 30 seconds with a 2.38% by mass TMAH aqueous solution to form a hole pattern with a dimension of 23 nm. Using a length-measuring SEM (CG6300) manufactured by Hitachi High-Tech Corporation, the exposure dose when a hole dimension of 23 nm was formed was measured and taken as the sensitivity. Also, the dimensions of 50 holes at this time were measured, and three times the standard deviation (σ) calculated from the results was taken as the CDU. The results are shown in Tables 7 and 8.

[0439]

Table 7

[0440]

Table 8

[0441] From the results shown in Tables 7 and 8, it was confirmed that the chemically amplified resist composition of the present invention has good sensitivity and excellent CDU.

[0442] [6] Dry etching resistance evaluation [Examples 5-1 to 5-25, Comparative Examples 5-1 to 5-15] 2 g of each of the polymers (Polymers P-1 to P-25, Comparative Polymers CP-1 to CP-15) shown in Tables 1 and 2 were dissolved in 10 g of cyclohexanone, and the polymer solution filtered through a 0.2 μm size filter was spin-coated on a Si substrate to form a film with a thickness of 300 nm, and evaluated under the following conditions. CHF 3 / CF 4 Etching test with a / CF-based gas: Using a dry etching apparatus TE-8500P manufactured by Tokyo Electron Limited, the film thickness difference of the polymer film before and after etching was determined. The etching conditions are as follows. Chamber pressure 40 Pa RF power 1000 W Gap 9 mm CHF 3 Gas flow rate 30 mL / min CF 4 Gas flow rate 30 mL / min Ar gas flow rate 100 mL / min Time 60 sec In this evaluation, a smaller film thickness difference, that is, a smaller reduction amount, indicates higher etching resistance. The results of the dry etching resistance are shown in Tables 9 and 10.

[0443]

Table 9

[0444]

Table 10

[0445] From the results shown in Tables 9 and 10, the polymer of the present invention has excellent dry etching resistance against CHF 3 / CF 4 -based gases was confirmed.

Claims

1. A polymer containing a repeating unit represented by the following formula (a) and a fluorosulfonic acid anion having a polymerizable group and an aromatic ring structure substituted with an iodine atom, and generating an acid upon exposure. 【Chemical 1】 (In the formula, m1 is 0 or 1. m2 is an integer of 0 to 3 when m1 is 0, and an integer of 0 to 5 when m1 is 1. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond to a carbon atom of the main chain. R 1 and R 2 is each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. Also, R 1 and R 2 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. R 3 is a halogen atom, a hydroxy group, a cyano group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a hetero atom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a hetero atom or -N(R 3A )(R 3B ). R 3A and R 3B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms. When m2 is 2 or more, a plurality of R 3 may combine with each other to form a ring together with the carbon atoms of the aromatic ring to which they are attached. L A is a single bond, an aliphatic hydrocarbylene group having 1 to 4 carbon atoms, a carbonyl group, a sulfonyl group, or a group obtained by combining these groups. L B and L C are each independently an oxygen atom or a sulfur atom, provided that L A and L C must be bonded to adjacent carbon atoms of the aromatic ring.)

2. L B and L C The polymer according to claim 1, wherein both are oxygen atoms.

3. L A The polymer according to claim 1, wherein L is a carbonyl group.

4. The polymer according to claim 1, wherein the repeating unit that generates an acid upon exposure is represented by the following formula (b). 【Chemical 2】 (In the formula, n1 is 0 or 1. n2 is 0 or 1. n3 is an integer of 0 to 4. n4 is an integer of 0 to 4. n5 is an integer of 1 to 6. However, when n2 is 0, 1 ≤ n4 + n5 ≤ 4, and when n2 is 1, 1 ≤ n4 + n5 ≤ 6. n6 is an integer of 0 to 4. n7 is 0 or 1. n8 is 0 or 1. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 11 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, a nitro group, or a hetero atom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a hetero atom, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a hetero atom. When n3 is 2, 3 or 4, a plurality of R 11 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. R 12 is a halogen atom other than an iodine atom, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a hetero atom, or a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a hetero atom. When n4 is 2, 3 or 4, a plurality of R 12 may be bonded to each other to form a ring together with the carbon atom to which they are bonded. L D 、 L E and L F is, independently of one another, a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a sulfonic acid amide bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. Q 1 and Q 2 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Q 3 and Q 4 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z + is an onium cation.)

5. The polymer according to claim 1, wherein the repeating unit represented by formula (b) is represented by the following formula (b1). 【Chemical Formula 3】 (wherein, R A , R 11 , R 12 , L D , L F , Q 1 to Q 4 , n1 to n6 and Z + are the same as described above.)

6. The polymer according to claim 5, wherein the repeating unit represented by formula (b1) is represented by the following formula (b2). [Chemical Formula 4] (wherein, R A , R 11 , R 12 , L D , Q 1 , Q 2 , n1 to n6 and Z + are the same as described above.)

7. Z + The polymer according to claim 1, wherein Z is a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). 【Chemical Formula 5】 (In the formula, R ct1 to R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. Further, R ct1 and R ct2 may combine with each other to form a ring together with the sulfur atom to which they are attached.)

8. Furthermore, the polymer according to claim 1, further containing a repeating unit represented by the following formula (c1). [Chemical Formula 6] (wherein R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.) X 1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond to a carbon atom of the main chain. R 21 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, a nitro group, a cyano group, or a hetero atom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a hetero atom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a hetero atom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a hetero atom. a is an integer of 1 to 4. b is an integer of 0 to 3. However, 1 ≤ a + b ≤ 5. )

9. Furthermore, the polymer according to claim 1, further containing a repeating unit represented by the following formula (d1) or (d2). 【Chemical Formula 7】 (wherein R A is each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.) Y 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O-Y 11 - or *-C(=O)-NH-Y 11 -, and the phenylene group or naphthylene group may be substituted with a C1-C10 alkoxy group or a halogen atom which may contain a hydroxy group, a nitro group, a cyano group, or a fluorine atom. Y 11 is a C1-C10 saturated hydrocarbylene group, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. Y 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond to a carbon atom of the main chain. AL 1 and AL 2 are each independently an acid-labile group. R 31 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom, a cyano group, a hydroxy group, a nitro group, or a hetero atom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a hetero atom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a hetero atom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a hetero atom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a hetero atom. c is an integer of 0 to 4. )

10. Furthermore, the polymer according to claim 1, further containing a repeating unit represented by the following formula (e1). 【Chemical 8】 (wherein, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.) Z 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O-Z 11 - or *-C(=O)-NH-Z 11 -, where the phenylene group or naphthylene group may be substituted with a C1-C10 alkoxy group or a halogen atom which may contain a hydroxy group, a nitro group, a cyano group, or a fluorine atom. * represents a bond to a carbon atom of the main chain. Z 11 is a C1-C10 saturated hydrocarbylene group, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. R 41 is a group having 1 to 20 carbon atoms and containing at least one or more structures selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (—C(═O)—O—C(═O)—).)

11. (A) A chemically amplified resist composition containing a base polymer containing the polymer according to any one of claims 1 to 10.

12. Furthermore, the chemically amplified resist composition according to claim 11, further containing (B) a quencher.

13. Furthermore, the chemically amplified resist composition according to claim 11, further containing (C) an organic solvent.

14. Furthermore, the chemically amplified resist composition according to claim 11, further containing (D) an acid generator.

15. Furthermore, the chemically amplified resist composition according to claim 11, further containing (E) a surfactant.

16. Furthermore, the chemically amplified resist composition according to claim 11, further containing (F) a dissolution inhibitor.

17. A pattern forming method comprising a step of forming a resist film on a substrate using the chemically amplified resist composition according to claim 11, a step of exposing the resist film to high energy rays, and a step of developing the exposed resist film using a developer.

18. The pattern forming method according to claim 17, wherein the high energy rays are ArF excimer laser light having a wavelength of 193 nm, KrF excimer laser light having a wavelength of 248 nm, an electron beam, or extreme ultraviolet rays having a wavelength of 3 to 15 nm.