Radiation-sensitive resin composition and method for forming resist pattern

Abstract

The present invention provides: a radiation-sensitive resin composition capable of manifesting an adequate level of sensitivity, LWR performance, and process margins when a next-generation exposure technique is applied; and a method for forming a resist pattern. The radiation-sensitive resin composition includes: a resin including a structural unit A indicated by formula (1) and a structural unit B having an acid-cleavable group (excluding that indicated in formula (1)); a radiation-sensitive acid generator; and a solvent. (In formula (1), RＸ is a hydrogen atom, a fluorine atom, a methyl group, or trifluoromethyl group. A is an aromatic hydrocarbon group that has: -ORY bonded to a carbon atom adjacent to the carbon atom to which Lα is bonded; and a hydrogen atom on another carbon atom that is unsubstituted or partially or wholly substituted by a cyano group, a nitro group, an alkyl group, an alkoxy group, an alkoxy carbonyl group, an alkoxy carbonyl oxy group, an acyl group, or an acyloxy group. RY is a hydrogen atom or a protective group that is de-protected by the action of acid. Lα represents a single bond or a divalent linking group.)

Description

[Technical field]

[0001] The present invention relates to a radiation-sensitive resin composition and a method for forming a resist pattern. [Background technology]

[0002] Photolithography techniques using resist compositions are used for forming fine circuits in semiconductor elements. As a typical procedure, for example, an acid is generated by exposing a coating of the resist composition to radiation through a mask pattern, and a difference in solubility of the resin in an alkaline or organic solvent-based developer is generated between an exposed portion and an unexposed portion by a reaction catalyzed by the acid, thereby forming a resist pattern on a substrate.

[0003] In the above photolithography technology, pattern miniaturization is being promoted by using short-wavelength radiation such as ArF excimer lasers, or by combining this radiation with liquid immersion lithography. As a next-generation technology, the use of even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is being attempted, and resist materials containing styrene-based resins with improved radiation absorption efficiency are also being considered. (Patent Document 1) [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-52294 A Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned next-generation technologies also require resist performance equal to or better than conventional ones in terms of sensitivity, line width roughness (LWR) performance indicating the variation in line width of the resist pattern, etc. Also, a process margin that makes it easy to control the conditions for pattern miniaturization is desired. However, existing radiation-sensitive resin compositions do not provide these properties at a sufficient level.

[0006] An object of the present invention is to provide a radiation-sensitive resin composition and a method for forming a resist pattern that are capable of exhibiting sufficient levels of sensitivity, LWR performance, and process margin when next-generation technology is applied. [Means for solving the problem]

[0007] As a result of intensive research into solving the above problem, the present inventors discovered that the above object can be achieved by adopting the following configuration, and thus completed the present invention.

[0008] That is, in one embodiment, the present invention provides A resin including a structural unit A represented by the following formula (1) and a structural unit B having an acid dissociable group (excluding those represented by the following formula (1)): A radiation-sensitive acid generator, and solvent The present invention relates to a radiation-sensitive resin composition comprising the above compound.

[0009] [ka] (In the above formula (1), R X is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a monovalent aromatic hydrocarbon group, L α -OR on the carbon atom next to the carbon atom to which Y is bonded to the carbon atom, and the hydrogen atoms on the other carbon atoms are unsubstituted or some or all of the hydrogen atoms are substituted with a cyano group, a nitro group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group.Y is a protecting group which is deprotected by the action of a hydrogen atom or an acid. L α is a single bond or a divalent linking group.

[0010] The radiation-sensitive resin composition contains a resin having the structural unit A, and therefore is capable of exhibiting sufficient levels of sensitivity, LWR performance, and process margin. Although the reason for this is unclear, it is presumed to be as follows. Y The group is L α The carbon atom next to the carbon atom to which L is bonded (i.e., α Ortho-position to the -OR, which can be a phenolic hydroxyl group. Y The group is L α It is presumed that the ortho-position of -OR toward the main chain of the resin reduces the solubility of the resin in the developer in the unexposed area, which results in a large effect on the increase in contrast between the exposed and unexposed areas. Y When the group is protected by a protecting group that is deprotected by the action of an acid, it is deprotected by the action of an acid to become a phenolic hydroxyl group, and the same contrast enhancing effect as above can be obtained. Note that the "acid-dissociable group" refers to a group that replaces a hydrogen atom of an alkali-soluble group such as a carboxyl group, a phenolic hydroxyl group, a sulfo group, or a sulfonamide group, and dissociates by the action of an acid. Therefore, the acid-dissociable group is bonded to the oxygen atom that was bonded to the hydrogen atom in these functional groups.

[0011] In another embodiment, the present invention provides a method for producing a photoresist film by using the radiation-sensitive resin composition, a step of exposing the resist film to light; and The present invention also relates to a method for forming a resist pattern, which comprises the step of developing the exposed resist film.

[0012] The method for forming a resist pattern uses the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity, LWR performance and process margin, and therefore enables the efficient formation of high-quality resist patterns by lithography employing next-generation exposure technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0014] 《Radiation-sensitive resin composition》 The radiation-sensitive resin composition according to the present embodiment (hereinafter, simply referred to as the "composition") contains a resin, a radiation-sensitive acid generator, and a solvent. The composition may contain other optional components as long as the effects of the present invention are not impaired.

[0015] <Resin> The resin is an assembly of polymers having a structural unit A and a structural unit B having an acid-dissociable group (excluding the structural unit A) (hereinafter, this resin is also referred to as a "base resin"). In addition to the structural units A and B, the base resin may have a structural unit C having a phenolic hydroxyl group, a structural unit D including at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure, and the like. Each structural unit will be described below.

[0016] (Structural unit A) The structural unit A is represented by the following formula (1). [ka]

[0017] In the above formula (1), R X is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a monovalent aromatic hydrocarbon group, L α -OR on the carbon atom next to the carbon atom to which Yis bonded to the carbon atom, and the hydrogen atoms on the other carbon atoms are unsubstituted or some or all of the hydrogen atoms are substituted with a cyano group, a nitro group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group. Y is a protecting group which is deprotected by the action of a hydrogen atom or an acid. L α is a single bond or a divalent linking group.

[0018] The aromatic hydrocarbon group refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure, but does not necessarily have to be composed of only an aromatic ring structure, and may also contain a chain structure or an alicyclic structure as part of it.

[0019] Examples of the aromatic hydrocarbon group represented by A include aryl groups such as phenyl, naphthyl, anthryl, phenanthryl, and pyrenyl groups, and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups. Among these, the aromatic hydrocarbon group is preferably an aryl group.

[0020] In the aromatic hydrocarbon group represented by A above, L α -OR on the carbon atom next to the carbon atom of the aromatic ring to which Y In other words, L α -OR for the carbon atom to which Y is bonded at the ortho position. R Y is a protecting group that is deprotected by the action of a hydrogen atom or an acid. This makes it possible to appropriately suppress the solubility of the resin in an alkaline developer in unexposed areas, thereby enabling the resin to exhibit excellent LWR performance, etc.

[0021] Examples of the protecting group that can be removed by the action of an acid include groups represented by the following formulae (AL-1) to (AL-3). [ka]

[0022] In the above formulas (AL-1) and (AL-2), R L1 and R L2 is a monovalent hydrocarbon group, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and is preferably an alkyl group having 1 to 40 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms. In formula (AL-1), a is an integer of 0 to 10, and preferably an integer of 1 to 5. In the above formulas (AL-1) to (AL-3), * is a bond to another moiety.

[0023] In the above formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a monovalent hydrocarbon group, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and is preferably an alkyl group having 1 to 20 carbon atoms. L2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen 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.

[0024] In the above formula (AL-3), R L5 , R L6 and R L7 are each independently a monovalent hydrocarbon group, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The monovalent hydrocarbon group may be linear, branched, or cyclic, and is preferably an alkyl group having 1 to 20 carbon atoms. L5 , R L6 and R L7 Any two of these may be bonded to each other together with the carbon atom to which they are bonded to form a ring having 3 to 20 carbon atoms. As the above ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0025] Among these, the protecting group which can be removed by the action of an acid is preferably the group represented by the above formula (AL-3).

[0026] In the above formula (1), A is α -OR to a carbon atom other than the carbon atom next to the carbon atom to which Y is preferably not bonded. This makes it possible to efficiently control the solubility of the structural unit A in an alkaline developer in the unexposed area, which can contribute to an increase in contrast.

[0027] Examples of the alkyl group that can substitute a hydrogen atom on a carbon atom of the aromatic hydrocarbon group include linear or branched alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, and propyl groups; and monocyclic or polycyclic cycloalkyl groups having 3 to 20 carbon atoms. Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 8 carbon atoms, such as methoxy, ethoxy, and tert-butoxy groups. Examples of the alkoxycarbonyl group include linear or alicyclic alkoxycarbonyl groups having 1 to 20 carbon atoms, such as methoxycarbonyl, butoxycarbonyl, and adamantylmethyloxycarbonyl groups. Examples of the alkoxycarbonyloxy group include linear or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as methoxycarbonyl, butoxycarbonyl, and adamantylmethyloxycarbonyl groups. Examples of the acyl group include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as an acetyl group, a propionyl group, a benzoyl group, and an acryloyl group. Examples of the acyloxy group include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as an acetyloxy group, a propionyloxy group, a benzoyloxy group, and an acryloyloxy group.

[0028] The above L α Examples of the divalent linking group represented by the formula (I) include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, * -R La O-, * -R LbCOO- and the like (* represents a bond on the oxygen side). A part or all of the hydrogen atoms of these groups may be substituted with halogen atoms such as fluorine atoms and chlorine atoms, cyano groups, and the like.

[0029] The alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms.

[0030] Examples of the cycloalkanediyl group include monocyclic cycloalkanediyl groups such as a cyclopentanediyl group and a cyclohexanediyl group, and polycyclic cycloalkanediyl groups such as a norbornanediyl group and an adamantanediyl group. The cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.

[0031] Examples of the alkenediyl group include an ethenediyl group, a propenediyl group, a butenediyl group, etc. The alkenediyl group is preferably an alkenediyl group having 2 to 6 carbon atoms.

[0032] the above * -R La O-R La Examples of the alkyl group include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, and the above-mentioned alkenediyl group. * -R Lb COO-R Lb Examples of the arenediyl group include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, the above-mentioned alkenediyl group, and arenediyl group. Examples of the arenediyl group include a phenylene group, a tolylene group, and a naphthylene group. The arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.

[0033] The structural unit represented by the above formula (1) is preferably a structural unit represented by any one of the following formulae (1-1) to (1-4).

[0034] [ka] (In the formula, R X, R Y and L α is defined as the above formula (1). R a1 , R a2 , R a3 and R a4 are each independently a cyano group, a nitro group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group. n1 is an integer of 0 to 4. n2, n3, and n4 are each independently an integer of 0 to 6. R a1 , R a2 , R a3 and R a4 If there are multiple of each, there are multiple R a1 , R a2 , R a3 and R a4 are the same or different.)

[0035] R a1 , R a2 , R a3 and R a4 The alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group and acyloxy group represented by the following formula (1) have the same meanings as those in the above formula (1).

[0036] Among these, R X is preferably a hydrogen atom or a methyl group. R Y is preferably a hydrogen atom. R a1 , R a2 , R a3 and R a4 is preferably each independently an alkyl group or an alkoxyl group.

[0037] n1 is preferably an integer of 0 to 2, and more preferably 0 or 1. n2, n3, and n4 are each independently preferably an integer of 0 to 4, and more preferably an integer of 0 to 2.

[0038] L α is a single bond or* -R La O- is preferred. La As L, an alkanediyl group is preferred. α It is more preferable that is a single bond.

[0039] The structural unit A is preferably any of structural units represented by the following formulae (A-1) to (A-12).

[0040] [ka] (In the above formulas (A-1) to (A-12), R X and R Y is the same as the above formula (1).

[0041] Among these, the structural units represented by the above formulae (A-1) to (A-4) and (A-9) to (A-11) are preferred.

[0042] A method for synthesizing a monomer compound that gives the structural unit A will be described using a monomer that gives the structural unit represented by the above formula (A-1) as an example. The monomer compound that gives the structural unit represented by the above formula (A-1) can be synthesized according to the following scheme.

[0043] [ka] (In the above scheme, R Y is the same as the above formula (1).

[0044] In the presence of a base, a nucleophilic substitution reaction between a 1,2-dihydroxybenzene derivative having a structure corresponding to the aromatic hydrocarbon group in the above formula (1) and an acyl halide having a polymerizable group (methacryloyl chloride in the scheme) is carried out in a solvent to synthesize a monomer compound. Other structures can also be synthesized in the same manner by controlling the structure of the dihydroxy aromatic hydrocarbon derivative used as the starting material.

[0045] The lower limit of the content of the structural unit A in the resin is preferably 2 mol%, more preferably 4 mol%, and even more preferably 5 mol%, based on the total structural units constituting the resin. The upper limit of the content is preferably 70 mol%, more preferably 50 mol%, and even more preferably 30 mol%. By setting the content of the structural unit A within the above range, the radiation-sensitive resin composition can further improve the sensitivity, LWR performance, and process margin.

[0046] (Structural unit B) Structural unit B is a structural unit that is different from structural unit A and contains an acid-dissociable group. Structural unit B is not particularly limited as long as it contains an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, a structural unit represented by the following formula (2) (hereinafter also referred to as "structural unit (B-1)") is preferred.

[0047] [ka]

[0048] In the above formula (2), R 7 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10 L each independently represents a monovalent linear hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these groups together with the carbon atom to which they are bonded. 1 represents a single bond or a divalent linking group. 1 When is a divalent linking group, the carbon atom bonded to the oxygen atom of -COO- in the above formula (2) is a tertiary carbon, or the structure on the terminal side of the side chain is -COO-.

[0049] Above R 7 From the viewpoint of copolymerizability of the monomer that gives the structural unit (B-1), a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[0050] Above R 8 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0051] Above R 8 ~R 10 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, and linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms.

[0052] Above R 8 ~R 10 Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1) include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that are not adjacent to each other among the carbon atoms constituting the alicyclic ring are bonded by a bond chain containing one or more carbon atoms.

[0053] Above R 8 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula: Examples of the alkyl group include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0054] Above R 8As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms and an alicyclic hydrocarbon group having 3 to 20 carbon atoms are preferable.

[0055] Above R 9 and R 10 The divalent alicyclic group having 3 to 20 carbon atoms, which is formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the formula (I) with each other and the carbon atoms to which they are bonded, is not particularly limited as long as it is a group in which two hydrogen atoms are removed from the same carbon atom constituting a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above carbon number. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Note that the condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed in such a way that multiple alicyclic rings share a side (a bond between two adjacent carbon atoms).

[0056] Among the monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Preferred polycyclic alicyclic hydrocarbon groups include bridged alicyclic saturated hydrocarbon groups, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1]heptane-2,2-diyl. 3,7 ]Decane-2,2-diyl group (adamantane-2,2-diyl group) and the like are preferred.

[0057] The above L 1 Examples of the divalent linking group represented by the formula (I) include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, * -R LA O-, * -R LB COO-, etc. (* indicates the bond on the oxygen side). * -R LBIn the case of groups other than COO-, the carbon atom bonded to the oxygen atom of -COO- in the above formula (2) is a tertiary carbon and does not have a hydrogen atom. This tertiary carbon is obtained when two bonds come out of the same carbon atom in the group, or when one or two further substituents are bonded to the carbon atom where one of the bonds is located in the group.

[0058] R 8 ~R 10 and L 1 Some or all of the hydrogen atoms on the carbon atoms in the alkyl group may be substituted with halogen atoms such as fluorine atoms or chlorine atoms, halogenated alkyl groups such as trifluoromethyl groups, alkoxy groups such as methoxy groups, cyano groups, or the like.

[0059] The alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms.

[0060] Examples of the cycloalkanediyl group include monocyclic cycloalkanediyl groups such as a cyclopentanediyl group and a cyclohexanediyl group, and polycyclic cycloalkanediyl groups such as a norbornanediyl group and an adamantanediyl group. The cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.

[0061] Examples of the alkenediyl group include an ethenediyl group, a propenediyl group, a butenediyl group, etc. The alkenediyl group is preferably an alkenediyl group having 2 to 6 carbon atoms.

[0062] the above * -R LA O-R LA Examples of the alkyl group include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, and the above-mentioned alkenediyl group. * -R LB COO-R LBExamples of the arenediyl group include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, the above-mentioned alkenediyl group, and arenediyl group. Examples of the arenediyl group include a phenylene group, a tolylene group, and a naphthylene group. The arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.

[0063] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and R 9 and R 10 It is preferable that the alicyclic structure formed by combining these with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure. 1 is a single bond or * -R LA O- is preferred. LA is preferably an alkanediyl group.

[0064] Examples of the structural unit (B-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (B-1-1) to (B-1-6)").

[0065] [ka]

[0066] In the above formulas (3-1) to (3-6), R 7 ~R 10 and R LA R has the same meaning as in formula (2) above. LM and R LN are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms. i and j are each independently an integer of 1 to 4. n A is 0 or 1.

[0067] R LM and R LN As the above, R in formula (2) 8 Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by the formula: LM and RLN As the alkyl group, a methyl group, an ethyl group or an isopropyl group is preferable.

[0068] As i and j, 1 is preferable. 8 ~R 10 As the alkyl group, a methyl group, an ethyl group or an isopropyl group is preferable.

[0069] Of these, the structural unit (B-1) is preferably the structural unit (B-1-1), the structural unit (B-1-2), the structural unit (B-1-4) or the structural unit (B-1-5). The structural unit (B-1-1) preferably has a cyclopentane structure. The structural unit (B-1-5) preferably has n A is preferably 0.

[0070] The base resin may contain one type of structural unit B or a combination of two or more types.

[0071] Furthermore, the resin may contain, as other structural units B, structural units represented by the following formulas (1f) to (2f).

[0072] [ka]

[0073] In the above formulas (1f) to (2f), R αf R each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βf are each independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. h1 is an integer of 1 to 4.

[0074] Above R βf is preferably a hydrogen atom, a methyl group or an ethyl group. h1 is preferably 1 or 2.

[0075] When the resin contains the structural unit B, the lower limit of the content of the structural unit B is preferably 10 mol%, more preferably 15 mol%, further preferably 20 mol%, and particularly preferably 30 mol% based on the total structural units constituting the base resin. The upper limit of the content is preferably 90 mol%, more preferably 80 mol%, further preferably 75 mol%, and particularly preferably 70 mol%. By setting the content of the structural unit C within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0076] (Structural unit C) The above resin preferably further contains a structural unit C represented by the following formula (cf).

[0077] [ka] (In the formula, R CF1 is a hydrogen atom or a methyl group. R CF2 is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. n f1 is an integer from 0 to 3. f1 If is 2 or 3, multiple R CF2 are the same or different. n f2 is an integer from 1 to 3. f1 +n f2 is 5 or less. af is an integer between 0 and 2.)

[0078] The structural unit C is a structural unit containing a phenolic hydroxyl group different from the structural unit A. The resin can adjust the solubility in the developer more appropriately by having the structural unit C and other structural units as necessary, and as a result, the sensitivity of the radiation-sensitive resin composition can be further improved. In addition, when KrF excimer laser light, EUV, electron beams, etc. are used as the radiation to be irradiated in the exposure step in the resist pattern forming method, the structural unit C contributes to improving the etching resistance and improving the difference in solubility in the developer between the exposed and unexposed parts (dissolution contrast). In particular, it can be suitably applied to pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV.

[0079] Above R CF1 From the viewpoint of copolymerizability of the monomer that gives the structural unit C, it is preferable that the substituent is a hydrogen atom.

[0080] The organic group refers to a group containing at least one carbon atom.

[0081] Above R CF2 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups containing a divalent heteroatom-containing group between the carbon atoms of this hydrocarbon group or at the bond-side terminal of this hydrocarbon group, and groups in which some or all of the hydrogen atoms in this group and the hydrocarbon group have been substituted with monovalent heteroatom-containing groups.

[0082] Above R CF2 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula: Alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group; alkenyl groups such as ethenyl, propenyl, and butenyl; Chain hydrocarbon groups such as alkynyl groups, e.g., ethynyl, propynyl, and butynyl; cycloalkyl groups such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a norbornyl group, and an adamantyl group; alicyclic hydrocarbon groups such as cycloalkenyl groups, e.g., cyclopropenyl, cyclopentenyl, cyclohexenyl, and norbornenyl; Aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, or an anthryl group; Examples include aromatic hydrocarbon groups such as aralkyl groups, eg, benzyl group, phenethyl group, and naphthylmethyl group.

[0083] Above R CF2 As the alkyl group, a chain hydrocarbon group or a cycloalkyl group is preferable, an alkyl group or a cycloalkyl group is more preferable, and a methyl group, an ethyl group, a propyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group or an adamantyl group is even more preferable.

[0084] Examples of the divalent heteroatom-containing group include -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'-, and combinations of two or more of these, where R' is a hydrogen atom or a monovalent hydrocarbon group.

[0085] Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxyl group, carboxy group, cyano group, amino group, and sulfanyl group (-SH).

[0086] Among these, a monovalent chain hydrocarbon group is preferred, an alkyl group is more preferred, and a methyl group is even more preferred.

[0087] Above n f1 is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0088] Above n f2 As the group, 1 and 2 are preferable, and 1 is more preferable.

[0089] Above n af As the number, 0 and 1 are preferable, and 0 is more preferable.

[0090] The structural unit C is preferably any of structural units represented by the following formulae (c1-1) to (c1-7).

[0091] [ka]

[0092] In the above formulas (c1-1) to (c1-7), R CF1 is the same as the above formula (cf).

[0093] Among these, the structural units represented by the above formulae (c1-1) to (c1-4) and the structural unit represented by the above formula (c1-6) are preferred.

[0094] When the resin contains the structural unit C, the lower limit of the content of the structural unit C is preferably 2 mol%, more preferably 4 mol%, further preferably 5 mol%, and particularly preferably 8 mol%, based on the total structural units constituting the resin. The upper limit of the content is preferably 50 mol%, more preferably 45 mol%, further preferably 40 mol%, and particularly preferably 35 mol%. By setting the content of the structural unit C within the above range, the radiation-sensitive resin composition can further improve the sensitivity, LWR performance, and process margin.

[0095] When a monomer having a phenolic hydroxyl group such as hydroxystyrene is polymerized, it is preferable to polymerize the monomer in a state in which the phenolic hydroxyl group is protected by a protecting group such as an alkali dissociable group, and then to obtain the structural unit B by deprotecting the monomer through hydrolysis. Examples of the structural unit that gives the structural unit B through hydrolysis include a structural unit represented by the following formula (c). For other structures, the phenolic hydroxyl group present in the structure may be protected so as to correspond to the structural unit B.

[0096] [ka]

[0097] In the above formula (c), R 11 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 12 R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 12 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include monovalent hydrocarbon groups having 1 to 20 carbon atoms. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0098] Above R 12 As the alkyl group, an alkyl group and an alkoxy group are preferable, and among them, a methyl group and a tert-butoxy group are more preferable.

[0099] (Structural unit D) The structural unit D is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. The base resin further contains the structural unit D, which allows the solubility in a developer to be adjusted, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. In addition, the adhesion between a resist pattern formed from the base resin and a substrate can be improved.

[0100] Examples of the structural unit D include structural units represented by the following formulae (T-1) to (T-10).

[0101] [ka]

[0102] In the above formula, R L1 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L4 and R L5L may be combined with each other to form a divalent alicyclic group having 3 to 8 carbon atoms together with the carbon atom to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0103] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining together with the carbon atom to which they are bonded include R 9 and R 10 Among divalent alicyclic groups having 3 to 20 carbon atoms constituted by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula (I) together with the carbon atoms to which they are bonded, groups having 3 to 8 carbon atoms are exemplified. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0104] The above L 2 Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0105] Of these, the structural unit D is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0106] When the resin has the structural unit D, the lower limit of the content is preferably 5 mol%, more preferably 8 mol%, and even more preferably 10 mol%, based on the total structural units constituting the base resin. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%. By setting the content of the structural unit D within the above range, the radiation-sensitive resin composition can further improve the lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0107] (Other structural units) The resin may appropriately have other structural units in addition to the above structural units A to D. Examples of the other structural units include structural units having a fluorine atom, an alcoholic hydroxyl group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. (hereinafter, also referred to as "structural unit E"). Among these, structural units having a fluorine atom, structural units having an alcoholic hydroxyl group, and structural units having a carboxy group are preferred, and structural units having a fluorine atom and structural units having an alcoholic hydroxyl group are more preferred.

[0108] Examples of the structural unit E include structural units represented by the following formula.

[0109] [ka]

[0110] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0111] When the resin has the structural unit E, the lower limit of the content ratio of the structural unit E to all structural units constituting the resin is preferably 1 mol%, more preferably 3 mol%, and even more preferably 5 mol%. On the other hand, the upper limit of the content ratio is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%. By setting the content ratio of the structural unit E in the above range, the solubility of the resin in the developer can be made more appropriate.

[0112] Incidentally, the structural units B to E exclude those structural units that fall under the structural unit A.

[0113] The content of the resin is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, based on the total solid content of the radiation-sensitive resin composition. Here, the "solid content" refers to all components contained in the radiation-sensitive resin composition excluding the solvent.

[0114] (Method of synthesizing resin) The base resin can be synthesized, for example, by polymerizing monomers that provide the respective structural units in a suitable solvent using a radical polymerization initiator or the like.

[0115] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

[0116] Examples of the solvent used in the polymerization reaction include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. The solvents used in these polymerization reactions may be used alone or in combination of two or more.

[0117] The reaction temperature in the above polymerization reaction is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0118] The molecular weight of the resin serving as the base resin is not particularly limited, but the weight average molecular weight (Mw) calculated based on polystyrene standards by gel permeation chromatography (GPC) is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the resin (A) is less than the lower limit, the heat resistance of the resulting resist film may decrease. If the Mw of the resin (A) is more than the upper limit, the developability of the resist film may decrease.

[0119] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0120] In this specification, the Mw and Mn of the resin are values ​​measured by gel permeation chromatography (GPC) under the following conditions. GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Elution solvent: Tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0121] The resin content is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0122] <Other resins> The radiation-sensitive resin composition of the present embodiment may contain, as another resin, a resin having a higher mass content of fluorine atoms than the base resin (hereinafter, also referred to as a "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, and as a result, the state of the resist film surface and the component distribution in the resist film can be controlled to a desired state.

[0123] The high fluorine content resin preferably has, for example, structural units A to C in the above base resin as necessary and also has a structural unit represented by the following formula (6) (hereinafter also referred to as "structural unit G"). [ka]

[0124] In the above formula (6), R 13is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. R 14 represents a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0125] Above R 13 From the viewpoint of copolymerizability of the monomer that gives the structural unit G, a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[0126] Above G L From the viewpoint of copolymerizability of the monomer that gives the structural unit G, a single bond and -COO- are preferable, and -COO- is more preferable.

[0127] Above R 14 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) include linear or branched alkyl groups having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0128] Above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the following formula include monocyclic or polycyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0129] Above R 14 As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group and a 5,5,5-trifluoro-1,1-diethylpentyl group are further preferable.

[0130] When the high fluorine content resin has the structural unit G, the lower limit of the content of the structural unit G is preferably 10 mol%, more preferably 15 mol%, further preferably 20 mol%, and particularly preferably 25 mol% based on the total structural units constituting the high fluorine content resin. The upper limit of the content is preferably 60 mol%, more preferably 50 mol%, and further preferably 40 mol%. By setting the content of the structural unit G within the above range, the mass content of fluorine atoms in the high fluorine content resin can be more appropriately adjusted, and the uneven distribution of fluorine atoms in the surface layer of the resist film can be further promoted.

[0131] The high fluorine content resin may have a fluorine atom-containing structural unit represented by the following formula (f-1) (hereinafter also referred to as structural unit H) in addition to the structural unit G. By having the structural unit H, the high fluorine content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects. [ka]

[0132] The structural unit H is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of an alkali to increase the solubility in an alkali developer (hereinafter, also referred to simply as an "alkali dissociable group"). In both (x) and (y), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a (s+1)-valent hydrocarbon group having 1 to 20 carbon atoms, and R of this hydrocarbon group E At the end of the side, there is an oxygen atom, a sulfur atom, and -NR dd R is a structure in which -, a carbonyl group, -COO- or -CONH- is bonded, or a structure in which some of the hydrogen atoms in the hydrocarbon group are replaced by an organic group having a hetero atom. dd represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s represents an integer of 1 to 3.

[0133] When the structural unit H has (x) an alkali-soluble group, R Fis a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 If is an oxygen atom, W 1 A 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit H has (x) an alkali-soluble group, it is possible to increase the affinity for an alkali developer and suppress development defects. As the structural unit H having (x) an alkali-soluble group, A 1 is an oxygen atom and W 1 It is particularly preferred that R is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0134] When the structural unit H has (y) an alkali dissociable group, R F is a monovalent organic group having 1 to 30 carbon atoms, 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S0-*, W 1 or R F A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to the carbon atom. 1 If is an oxygen atom, W 1 , R E is a single bond, and RD R is a hydrocarbon group having 1 to 20 carbon atoms. E A carbonyl group is bonded to the end of the R F is an organic group having a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit H has (y) an alkali dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkaline development step. As a result, the affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. As the structural unit H having (y) an alkali dissociable group, A 1 is -COO-* and R F Or W 1 Or, it is particularly preferable that both of them have a fluorine atom.

[0135] R C From the viewpoint of copolymerizability of the monomer that gives the structural unit H, etc., a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[0136] R E When is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and more preferably a group having a norbornane lactone structure.

[0137] When the high fluorine content resin has the structural unit H, the lower limit of the content of the structural unit H is preferably 10 mol%, more preferably 20 mol%, further preferably 30 mol%, and particularly preferably 35 mol%, based on the total structural units constituting the high fluorine content resin. The upper limit of the content is preferably 90 mol%, more preferably 75 mol%, and further preferably 60 mol%. By setting the content of the structural unit H in the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0138] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, further preferably 20,000, and particularly preferably 15,000.

[0139] The lower limit of Mw / Mn of the high fluorine content resin is usually 1, and more preferably 1.1. The upper limit of the Mw / Mn is usually 5, and is preferably 3, more preferably 2, and even more preferably 1.7.

[0140] The lower limit of the content of the high fluorine content resin is preferably 0.1 mass%, more preferably 0.5 mass%, further preferably 1 mass%, and even more preferably 1.5 mass%, based on the total solid content in the radiation-sensitive resin composition. The upper limit of the content is preferably 20 mass%, more preferably 15 mass%, further preferably 10 mass%, and particularly preferably 7 mass%.

[0141] The lower limit of the content of the high fluorine content resin is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 1.5 parts by mass, relative to 100 parts by mass of the base resin. The upper limit of the content is preferably 15 parts by mass, more preferably 10 parts by mass, even more preferably 8 parts by mass, and particularly preferably 5 parts by mass.

[0142] By setting the content of the high fluorine content resin within the above range, the high fluorine content resin can be more effectively unevenly distributed in the surface layer of the resist film, and as a result, the water repellency of the surface of the resist film during immersion exposure can be further improved. The radiation-sensitive resin composition may contain one or more types of high fluorine content resins.

[0143] (Method of synthesizing high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the above-mentioned method for synthesizing the base resin.

[0144] <Radiation-sensitive acid generator> The radiation-sensitive acid generator is a component that generates an acid upon exposure to light. The radiation-sensitive acid generator is preferably represented by the following formula (p-1). [ka] (In the above formula (p-1), R p1 is a monovalent group containing a ring structure having six or more ring members. R p2 is a divalent linking group. R p3 and R p4 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R p5 and R p6 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n p1 is an integer from 0 to 10. p2 is an integer from 0 to 10. p3 is an integer from 0 to 10. p1 +n p2 +n p3 is an integer between 1 and 30. n p1 If is 2 or more, multiple R p2 are the same or different from each other. n p2 If is 2 or more, multiple R p3 are the same or different, and multiple R p4 are the same or different from each other. n p3 If is 2 or more, multiple R p5 are the same or different, and multiple R p6 are the same or different. Z + is a monovalent onium cation.

[0145] R p1Examples of the monovalent group containing a ring structure represented by the formula (I) include a monovalent group containing an alicyclic structure having 5 or more ring members, a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members, a monovalent group containing an aromatic ring structure having 6 or more ring members, and a monovalent group containing an aromatic heterocyclic structure having 6 or more ring members.

[0146] Examples of the alicyclic structure having 5 or more ring members include a monocyclic cycloalkane structure such as a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, or a cyclododecane structure; A monocyclic cycloalkene structure such as a cyclopentene structure, a cyclohexene structure, a cycloheptene structure, a cyclooctene structure, or a cyclodecene structure; Polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure; Examples include a norbornene structure and a polycyclic cycloalkene structure such as a tricyclodecene structure.

[0147] Examples of the aliphatic heterocyclic structure having 5 or more ring members include Lactone structures such as a pentanolactone structure, a hexanolactone structure, a norbornanelactone structure, etc.; Sultone structures such as a pentano sultone structure, a hexano sultone structure, and a norbornane sultone structure; Oxygen atom-containing heterocyclic structures such as an oxacyclopentane structure, an oxacycloheptane structure, an oxanorbornane structure, etc.; Nitrogen atom-containing heterocyclic structures such as an azacyclopentane structure, an azacyclohexane structure, and a diazabicyclooctane structure; Examples of the heterocyclic structure include a sulfur atom-containing heterocyclic structure such as a thiacyclopentane structure, a thiacyclohexane structure, and a thianorbornane structure.

[0148] Examples of the aromatic ring structure having 6 or more ring members include a benzene structure, a naphthalene structure, a phenanthrene structure, and an anthracene structure.

[0149] Examples of the aromatic heterocyclic structure having 6 or more ring members include oxygen atom-containing heterocyclic structures such as a furan structure, a pyran structure, and a benzopyran structure, and nitrogen atom-containing heterocyclic structures such as a pyridine structure, a pyrimidine structure, and an indole structure.

[0150] R p1 The lower limit of the number of ring members of the ring structure may be 6, preferably 7, more preferably 8, even more preferably 9, and particularly preferably 10. On the other hand, the upper limit of the number of ring members is preferably 15, more preferably 14, even more preferably 13, and particularly preferably 12. By setting the number of ring members within the above range, the diffusion length of the acid can be further suitably shortened, and as a result, various performances of the chemically amplified resist material can be further improved.

[0151] R p1 A part or all of the hydrogen atoms in the ring structure may be substituted with a substituent. Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, and acyloxy group. Among these, a hydroxy group is preferred.

[0152] R p1 As the aryl group, a monovalent group containing an alicyclic structure having 5 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members are preferable, a monovalent group containing an alicyclic structure having 6 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members are more preferable, a monovalent group containing an alicyclic structure having 9 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members are even more preferable, an adamantyl group, a hydroxyadamantyl group, a norbornane lactone-yl group, a norbornane sultone-yl group and a 5-oxo-4-oxatricyclo[4.3.1.13,8]undecane-yl group are even more preferable, and an adamantyl group is particularly preferable.

[0153] R p2Examples of the divalent linking group represented by the formula (I) include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, and a divalent hydrocarbon group. p2 The divalent linking group represented by the formula (I) is preferably a carbonyloxy group, a sulfonyl group, an alkanediyl group, or a cycloalkanediyl group, more preferably a carbonyloxy group or a cycloalkanediyl group, further preferably a carbonyloxy group or a norbornanediyl group, and particularly preferably a carbonyloxy group.

[0154] R p3 and R p4 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include an alkyl group having 1 to 20 carbon atoms. p3 and R p4 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) include a fluorinated alkyl group having 1 to 20 carbon atoms. p3 and R p4 As the alkyl group, a hydrogen atom, a fluorine atom and a fluorinated alkyl group are preferable, a fluorine atom and a perfluoroalkyl group are more preferable, and a fluorine atom and a trifluoromethyl group are further preferable.

[0155] R p5 and R p6 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) include a fluorinated alkyl group having 1 to 20 carbon atoms. p5 and R p6 As the alkyl group, a fluorine atom and a fluorinated alkyl group are preferable, a fluorine atom and a perfluoroalkyl group are more preferable, a fluorine atom and a trifluoromethyl group are further preferable, and a fluorine atom is particularly preferable.

[0156] n p1 As the aryl group, an integer of 0 to 5 is preferable, an integer of 0 to 3 is more preferable, an integer of 0 to 2 is further preferable, and 0 and 1 are particularly preferable.

[0157] n p2As the number, an integer of 0 to 2 is more preferable, 0 and 1 are further preferable, and 0 is particularly preferable.

[0158] n p3 is preferably an integer of 0 to 5, more preferably an integer of 1 to 4, further preferably an integer of 1 to 3, and particularly preferably 1 or 2. p3 By making n equal to or greater than 1, the strength of the acid generated from the compound of formula (p-1) can be increased, and as a result, the LWR performance and the like of the radiation-sensitive resin composition can be further improved. p3 The upper limit of is preferably 4, more preferably 3, and even more preferably 2.

[0159] In the above formula (p-1), n p1 +n p2 +n p3 is an integer between 1 and 30. p1 +n p2 +n p3 The lower limit of n is preferably 2, and more preferably 4. p1 +n p2 +n p3 The upper limit of is preferably 20, more preferably 10.

[0160] Above Z + Examples of the monovalent onium cation represented by the formula (X-1) include radioactive onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, and examples thereof include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, and pyridinium cations. Among these, sulfonium cations and iodonium cations are preferred. The sulfonium cations and iodonium cations are preferably represented by the following formulas (X-1) to (X-6).

[0161] [ka]

[0162] [ka]

[0163] [ka]

[0164] [ka]

[0165] [ka]

[0166] [ka]

[0167] In the above formula (X-1), R a1 , R a2 and R a3 each independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q Or -SR T or a ring structure formed by combining two or more of these groups together. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton. R P , R Q and R T are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently an integer of 0 to 5. R a1 ~Ra3 And R P , R Q and R T If there are multiple R a1 ~R a3 And R P , R Q and R T may be the same or different.

[0168] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer from 0 to 7. b1 If there are multiple, multiple R b1 may be the same or different, and multiple R b1 R may represent a ring structure formed by combining with each other. b2 L is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. C is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R b2 If there are multiple, multiple R b2 may be the same or different, and multiple R b2 may represent a ring structure formed by combining with each other. q is an integer of 0 to 3. In the formula, S + The ring structure containing the following may contain a heteroatom such as O or S between the carbon-carbon bonds that form the backbone.

[0169] In the above formula (X-3), R c1 , R c2 and R c3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0170] In the above formula (X-4), R g1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. k2 When is 0, k10 is an integer from 0 to 4, and n k2 When is 1, k10 is an integer from 0 to 7. R g1 If there are multiple, multiple R g1 may be the same or different, and multiple R g1 R may represent a ring structure formed by combining with each other. g2 and R g3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups together. k11 and k12 are each independently an integer of 0 to 4. R g2 and R g3 If there are multiple R g2 and R g3 may be the same or different.

[0171] In the above formula (X-5), R d1 and R d2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by combining two or more of these groups together. k6 and k7 are each independently an integer of 0 to 5. R d1 and R d2 If there are multiple R d1 and Rd2 may be the same or different.

[0172] In the above formula (X-6), R e1 and R e2 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0173] Examples of the radiation-sensitive acid generator represented by formula (p-1) above include radiation-sensitive acid generators represented by the following formulas (p-1-1) to (p-1-35) (hereinafter also referred to as "radiation-sensitive acid generator (p-1-1) to radiation-sensitive acid generator (p-1-35)").

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] In the above formulas (p-1-1) to (p-1-35), Z + is a monovalent onium cation.

[0178] Among these, the radiation-sensitive acid generators represented by the above formulas (p-1-9), (p-1-13), (p-1-17), (p-1-23), (p-1-25) and (p-1-35) are preferred.

[0179] These radiation-sensitive acid generators may be used alone or in combination of two or more. The lower limit of the content of the radiation-sensitive acid generator is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 5 parts by mass, relative to 100 parts by mass of the resin. The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, and even more preferably 30 parts by mass. This allows the resist pattern to exhibit excellent sensitivity, LWR performance, and process margin when forming the resist pattern.

[0180] <Acid diffusion control agent> The radiation-sensitive resin composition may contain an acid diffusion controller as necessary. The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the radiation-sensitive acid generator upon exposure, and has the effect of suppressing undesirable chemical reactions in non-exposed regions. In addition, the storage stability of the obtained radiation-sensitive resin composition is improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to fluctuations in the delay time from exposure to development treatment can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0181] Examples of the acid diffusion controller include a compound represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

[0182] [ka]

[0183] In the above formula (7), R 22 , R 23 and R 24 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0184] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline.

[0185] Examples of the nitrogen-containing compound (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0186] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethylacrylamide; and the like.

[0187] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0188] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0189] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazines, pyrazoles, and the like.

[0190] In addition, as the nitrogen-containing organic compound, a compound having an acid dissociable group can also be used.As the nitrogen-containing organic compound having an acid dissociable group, for example, Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine, etc. can be mentioned.

[0191] Also, as the acid diffusion control agent, an onium salt compound that generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon irradiation with radiation (hereinafter, for convenience, also referred to as a "radiation-sensitive weak acid generator") can be suitably used. The acid generated from the radiation-sensitive weak acid generator is a weak acid that does not induce dissociation of the acid-dissociable group in the resin under conditions that dissociate the acid-dissociable group. In this specification, "dissociation" of the acid-dissociable group refers to dissociation upon post-exposure baking at 110°C for 60 seconds.

[0192] Examples of the radiation-sensitive weak acid generator include a sulfonium salt compound represented by the following formula (8-1) and an iodonium salt compound represented by the following formula (8-2).

[0193] [ka]

[0194] In the above formula (8-1) and formula (8-2), J + is a sulfonium cation, and U + is the iodonium cation. + Examples of the sulfonium cation represented by the formula (X-1) to (X-4) include the sulfonium cation represented by the formula (X-1) to (X-4). +Examples of the iodonium cation represented by the formula (X-5) to (X-6) include the iodonium cation represented by the formula (X-6). - and Q - are each independently OH - , R α -COO - , R α -SO3 - It is an anion represented by R α R is an alkyl group, an aryl group, or an aralkyl group. α or a hydrogen atom of an aromatic ring of an aryl group or an aralkyl group may be substituted with a halogen atom, a hydroxy group, a nitro group, a halogen atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0195] Examples of the radiation-sensitive weak acid generator include compounds represented by the following formula:

[0196] [ka]

[0197] [ka]

[0198] The lower limit of the content of the acid diffusion controller is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol% based on the total moles of the radiation-sensitive acid generator. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol%. By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more types of acid diffusion controller.

[0199] <Solvent> The radiation-sensitive resin composition according to the present embodiment contains a solvent. The solvent is not particularly limited as long as it is a solvent that can dissolve or disperse at least the resin and the radiation-sensitive acid generator, as well as additives and the like that are contained as desired.

[0200] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0201] Examples of alcohol-based solvents include: Monoalcohol solvents having 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; Polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples of the polyhydric alcohol partially etherified solvents include those obtained by etherifying some of the hydroxy groups of the above-mentioned polyhydric alcohol solvents.

[0202] Examples of ether solvents include: Dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); Examples of the polyhydric alcohol solvent include polyhydric alcohol ether solvents obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.

[0203] Examples of ketone solvents include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclic ketone solvents such as cyclopentanone, cyclohexanone, methylcyclohexanone, etc. Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0204] Examples of the amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples of the solvent include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0205] Examples of ester-based solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of the solvent include polyvalent carboxylate diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0206] Examples of the hydrocarbon solvent include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0207] Among these, ester-based solvents and ketone-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents and lactone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0208] <Other optional ingredients> The radiation-sensitive resin composition may contain other optional components in addition to the above components. Examples of the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0209] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, which (1) induces a crosslinking reaction in the polymer component by an acid catalysis in the baking step after the floodwise exposure step, and (1) increases the molecular weight of the polymer component, thereby decreasing the solubility of the patternwise exposed area in the developer. Examples of the functional group include a (meth)acryloyl group, a hydroxymethyl group, an alkoxymethyl group, an epoxy group, and a vinyl ether group.

[0210] (Uneven distribution promoter) The uneven distribution promoter has the effect of making the high fluorine content resin unevenly distributed on the resist film surface more efficiently. By incorporating this uneven distribution promoter in the radiation-sensitive resin composition, the amount of the high fluorine content resin added can be reduced compared to the conventional case. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress the elution of components from the resist film into the immersion medium, and perform immersion exposure at a higher speed by high-speed scanning, thereby improving the hydrophobicity of the resist film surface, which suppresses immersion-induced defects such as watermark defects. Examples of the uneven distribution promoter that can be used include low-molecular compounds having a relative dielectric constant of 30 to 200 and a boiling point of 100° C. or higher at 1 atmospheric pressure. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, polyhydric alcohols, and the like.

[0211] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.

[0212] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

[0213] The nitrile compound may, for example, be succinonitrile.

[0214] An example of the polyhydric alcohol is glycerin.

[0215] The lower limit of the content of the uneven distribution promoter is preferably 10 parts by mass, more preferably 15 parts by mass, further preferably 20 parts by mass, and further preferably 25 parts by mass, relative to 100 parts by mass of the total amount of the resin in the radiation-sensitive resin composition. The upper limit of the content is preferably 300 parts by mass, more preferably 200 parts by mass, further preferably 100 parts by mass, and particularly preferably 80 parts by mass. The radiation-sensitive resin composition may contain one or more kinds of uneven distribution promoters.

[0216] (Surfactant) The surfactant has the effect of improving the coating property, striation, developability, etc. Examples of the surfactant include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and No. Examples include F-TOP EF301, EF303, and EF352 (all manufactured by Tochem Products), Megafac F171 and F173 (all manufactured by DIC), Fluorad FC430 and FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, and SC-106 (all manufactured by Asahi Glass Co., Ltd.). The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0217] (Alicyclic skeleton-containing compounds) The alicyclic skeleton-containing compound exhibits the effect of improving dry etching resistance, pattern shape, adhesion to a substrate, and the like.

[0218] Examples of the alicyclic skeleton-containing compound include Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, and 2-ethoxyethyl lithocholic acid; Examples include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane, etc. The content of the alicyclic skeleton-containing compound in the radiation-sensitive resin composition is usually 5 parts by mass or less based on 100 parts by mass of the resin.

[0219] (sensitizer) The sensitizer acts to increase the amount of acid generated from the radiation-sensitive acid generator or the like, and exerts the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0220] Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0221] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing a resin, a radiation-sensitive acid generator, a high-fluorine content resin if necessary, and a solvent in a predetermined ratio. After mixing, the radiation-sensitive resin composition is preferably filtered, for example, through a filter having a pore size of about 0.05 μm to 0.20 μm. The solid content concentration of the radiation-sensitive resin composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

[0222] <<Method of forming a resist pattern>> The method for forming a resist pattern according to the present invention comprises the steps of: A step (1) of forming a resist film from the radiation-sensitive resin composition (hereinafter also referred to as a "resist film forming step"); A step (2) of exposing the resist film to light (hereinafter also referred to as an "exposure step"); and The method includes a step (3) of developing the exposed resist film (hereinafter also referred to as the "developing step").

[0223] According to the above-mentioned method for forming a resist pattern, since the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity, LWR performance, and process margin in the exposure step, is used, a high-quality resist pattern can be formed. Each step will be described below.

[0224] [Resist film formation process] In this step (step (1) above), a resist film is formed from the radiation-sensitive resin composition. Examples of the substrate on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide, and aluminum-coated wafers. In addition, an organic or inorganic anti-reflective film disclosed in, for example, JP-B-6-12452 and JP-A-59-93448 may be formed on the substrate. Examples of the coating method include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed as necessary to volatilize the solvent in the coating film. The PB temperature is usually 60° C. to 140° C., and preferably 80° C. to 120° C. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0225] When performing immersion exposure, regardless of the presence or absence of the water-repellent polymer additive such as the high fluorine content resin in the radiation-sensitive resin composition, a protective film for immersion that is insoluble in the immersion liquid may be provided on the formed resist film in order to prevent direct contact between the immersion liquid and the resist film. As the protective film for immersion, either a solvent-peelable protective film that is peeled off with a solvent before the development step (see, for example, JP-A-2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development step (see, for example, WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective film for immersion.

[0226] When the next exposure step is carried out with radiation having a wavelength of 50 nm or less, it is preferable to use a resin having the structural unit B, if necessary, in addition to the structural unit A, as the base resin in the composition.

[0227] [Exposure process] In this step (step (2) above), the resist film formed in the resist film forming step (1) above is exposed to radiation through a photomask (or, in some cases, through an immersion medium such as water). Examples of radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, are even more preferred.

[0228] When the exposure is performed by immersion exposure, the immersion liquid used may be, for example, water or a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a temperature coefficient of refractive index as small as possible so as to minimize distortion of the optical image projected onto the film, but when the exposure light source is an ArF excimer laser light (wavelength 193 nm), in addition to the above-mentioned viewpoint, water is preferably used from the viewpoint of ease of availability and ease of handling. When water is used, a small proportion of an additive that reduces the surface tension of water and increases the surfactant power may be added. It is preferable that this additive does not dissolve the resist film on the wafer and has a negligible effect on the optical coating on the lower surface of the lens. Distilled water is preferably used as the water to be used.

[0229] After the exposure, it is preferable to perform post-exposure baking (PEB) to promote dissociation of acid-dissociable groups of resins and the like by the acid generated from the radiation-sensitive acid generator by exposure in the exposed parts of the resist film. This PEB causes a difference in solubility in a developer between the exposed parts and the unexposed parts. The PEB temperature is usually 50°C to 180°C, and preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[0230] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (2) above is developed. This allows a desired resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0231] In the case of alkaline development, examples of the developer used in the development include an alkaline aqueous solution in which at least one of alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved. Among these, an aqueous TMAH solution is preferred, and a 2.38 mass % aqueous TMAH solution is more preferred.

[0232] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, or solvents containing organic solvents. Examples of the organic solvent include one or more of the solvents listed as the solvents for the radiation-sensitive resin composition described above. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, acetate solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As the ketone solvent, chain ketones are preferred, and 2-heptanone is more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0233] Examples of development methods include a method in which a substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time (paddle method), a method in which developer is sprayed onto the substrate surface (spray method), and a method in which developer is continuously dispensed by scanning a developer dispensing nozzle at a constant speed over a substrate rotating at a constant speed (dynamic dispense method). EXAMPLES

[0234] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below.

[0235] [Measurement of weight average molecular weight (Mw), number average molecular weight (Mn) and dispersity (Mw / Mn)] Measurement was performed under the measurement conditions described in the section on resins. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0236] [ 1 H-NMR analysis and 13 C-NMR analysis] Measurements were performed using JEOL's "JNM-Delta400."

[0237] <Resin synthesis> The monomers used in the synthesis of each resin in each Example and Comparative Example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value when the total mass of the monomers used is 100 parts by mass, and % by mole refers to a value when the total number of moles of the monomers used is 100 mol %. In addition, the present invention is not limited to the following structural units.

[0238] Among the monomers used in the synthesis of the resin in each Example, the structure of the monomer that gives the structural unit represented by the above formula (1) (that is, structural unit A) is shown below. [ka]

[0239] Among the monomers used in the synthesis of the resin in each of the Examples and Comparative Examples, the structures of the monomers other than the monomer that gives the above structural unit A are shown below. [ka]

[0240] (Synthesis of Monomer (M-1)) The monomer (M-1) providing the structural unit A was synthesized according to the following scheme.

[0241] [ka]

[0242] 200g (1.816mol) of catechol and 91.89g (0.908mol) of triethylamine were weighed into a 3L eggplant flask and dissolved in dichloromethane (1500mL). After cooling the solvent to 0°C, 94.93g (0.908mol) of methacryloyl chloride was added dropwise at a rate not exceeding 25°C. After the dropwise addition, the mixture was stirred at 25°C for 1.5 hours. After the reaction was completed, the mixture was quenched with a saturated aqueous solution of ammonium chloride and extracted with methylene chloride. The residue obtained by vacuum concentration was purified by column chromatography to obtain 65.08g (yield 20%) of monomer (M-1).

[0243] Other monomers (M-2) to (M-9) which provide the structural unit A were synthesized in the same manner as for the monomer (M-1), except that the precursors were appropriately changed.

[0244] [Synthesis Example 1] (Synthesis of Resin (A-1)) Monomer (M-1), monomer (M-10), and monomer (M-19) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total monomer amount) so that the molar ratio was 10 / 30 / 60. Next, 6 mol% of AIBN was added as an initiator relative to the total monomers to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total monomer amount) was added to an empty reaction vessel and heated to 85°C while stirring. Next, the monomer solution prepared above was dropped over 3 hours, and then heated at 85°C for another 3 hours, and the polymerization reaction was carried out for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature. The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, then filtered and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and hydrolysis reaction was carried out at 70 ° C for 6 hours while stirring. After the reaction was completed, the remaining solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass). The resin was solidified by dropping into 500 parts by mass of water, and the obtained solid was filtered. The resin was dried at 50 ° C for 12 hours to synthesize a white powdery resin (A-1).

[0245] [Synthesis Examples 2-30, 33-36, 38-42] (Synthesis of Resins (A-2) to (A-39)) Resins (A-2) to (A-39) were synthesized in the same manner as in Synthesis Example 1, except that the types of monomers shown in Table 1 were mixed in the specified amounts. Table 1 also shows the Mw, Mw / Mn, and content of structural units derived from each monomer in each resin obtained.

[0246] [Synthesis Example 31] (Synthesis of Resin (B-1)) Monomer (M-1), monomer (M-21), and monomer (M-32) were dissolved in 2-butanone (200 parts by mass relative to the total monomer amount) so that the molar ratio was 40 / 45 / 15. AIBN was added as an initiator in an amount of 6 mol% relative to the total monomers to prepare a monomer solution. Meanwhile, 2-butanone (100 parts by mass) was placed in an empty reaction vessel and heated to 80°C while stirring. Next, the monomer solution prepared above was dropped over 3 hours, and then heated at 80°C for another 3 hours, and the polymerization reaction was carried out for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature. The cooled polymerization solution was poured into methanol (2000 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The obtained solid was dissolved in acetone (100 parts by mass). The resin was coagulated by dropping it into 500 parts by mass of water, and the obtained solid was filtered off. The mixture was dried at 50° C. for 12 hours to synthesize a white powdery resin (B-1).

[0247] [Synthesis Examples 32 and 37] (Synthesis of polymers (B-2) and (B-3)) Resins (B-2) and (B-3) were obtained in the same manner as in Synthesis Example 31, except that the types of monomers shown in Table 1 were used in the prescribed amounts. Table 1 also shows the Mw, Mw / Mn, and content of structural units derived from each monomer in each resin obtained.

[0248] [Table 1]

[0249] <Preparation of Radiation-Sensitive Resin Composition> The radiation-sensitive acid generator, the acid diffusion controller and the solvent that constitute the radiation-sensitive resin composition are described below.

[0250] (Radiation-sensitive acid generator) C-1 to C-9: Compounds represented by the following formulas (C-1) to (C-9). [ka]

[0251] (Acid diffusion control agent) D-1 to D-9: Compounds represented by the following formulas (D-1) to (D-9). [ka]

[0252] (solvent) E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol 1-monomethyl ether

[0253] [Example 1] 100 parts by mass of resin (A-1), 20 parts by mass of (C-1) as a radiation-sensitive acid generator, 20 mol% of (D-1) as an acid diffusion controller relative to (C-1), 4,800 parts by mass of (E-1) as a solvent, and 2,000 parts by mass of (E-2) were mixed together. The mixture was then filtered through a membrane filter with a pore size of 0.20 μm to prepare a radiation-sensitive resin composition (R-1).

[0254] [Examples 2 to 55 and Comparative Examples 1 to 5] Radiation-sensitive resin compositions (R-2) to (R-55) and (CR-1) to (CR-5) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 2 below were used.

[0255] [Table 2]

[0256] <Formation of Resist Pattern> (EUV exposure, alkaline development) The radiation-sensitive resin composition prepared above was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (AL412 (Brewer Science)) was formed, using a spin coater (CLEAN TRACK ACT12, Tokyo Electron). After SB was performed at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a resist film with a thickness of 50 nm. Next, the resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", ASML, NA=0.33, illumination conditions: Conventional s=0.89, mask imecDEFECT32FFR02). Next, the wafer was developed for 30 seconds at 23°C using a 2.38 wt% TMAH aqueous solution to form a positive 32 nm line and space pattern.

[0257] <Evaluation> The resist patterns thus formed were measured according to the following methods to evaluate the sensitivity, LWR performance, and process window of each radiation-sensitive resin composition. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the resist patterns. The evaluation results are shown in Table 3 below.

[0258] [sensitivity] In forming the resist pattern, the exposure dose for forming a 32 nm line and space pattern was determined as the optimum exposure dose, and this optimum exposure dose was calculated based on the sensitivity (mJ / cm 2 The sensitivity was 30 mJ / cm 2 The following are considered "good": 30mJ / cm 2 If it exceeded this, it was judged as “poor”.

[0259] [LWR performance] The resist pattern was observed from above using the above scanning electron microscope. The line width was measured at 50 arbitrary points, and the 3 sigma value was calculated from the distribution of the measured values, which was used as the LWR performance. The smaller the value, the better the LWR performance. The LWR performance was judged as good when it was 4.0 nm or less, and poor when it was over 4.0 nm.

[0260] [Process Window] Patterns were formed from low to high exposure doses using a mask that forms 32 nm lines and spaces (1L / 1S). Generally, defects such as connection between patterns are seen on the low exposure dose side, and pattern collapse are seen on the high exposure dose side. The difference between the upper and lower limit values ​​of the resist dimensions where these defects are not seen is defined as the "CD margin", and a CD margin of 30 nm or more was judged to be good, and one less than 30 nm was judged to be bad. It is believed that the larger the CD margin value, the wider the process window.

[0261] [Table 3]

[0262] As is clear from the results in Table 3, the radiation-sensitive resin compositions of the Examples were all superior in sensitivity, LWR performance, and CD margin compared to the radiation-sensitive resin compositions of the Comparative Examples. [Industrial Applicability]

[0263] The radiation-sensitive resin composition and the method for forming a resist pattern of the present invention can improve sensitivity, LWR, and process margin compared to conventional methods, and therefore can be suitably used for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A resin including a structural unit A represented by the following formula (1) and a structural unit B having an acid dissociable group (excluding those represented by the following formula (1)): A radiation-sensitive acid generator represented by the following formula (p-1), solvent A radiation-sensitive resin composition comprising: 【Chemistry 1】 (In the above formula (1), R Ｘ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a monovalent aromatic hydrocarbon group, L α -OR to the carbon atom next to the carbon atom to which Ｙ is bonded to the carbon atom, and the hydrogen atoms on the other carbon atoms are unsubstituted or some or all of the hydrogen atoms are substituted with a cyano group, a nitro group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group. Ｙ is a protecting group which is deprotected by the action of a hydrogen atom or an acid. L α is a single bond or a divalent linking group. 【Chemistry 2】 (In the formula, R p1 is a monovalent group containing a ring structure having 6 or more ring members. Some or all of the hydrogen atoms in the ring structure are substituted with iodine atoms. R p2 is a divalent linking group. R p3 and R p4 each independently represent a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R p5 and R p6 each independently represent a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n p1 is an integer of 0 to 10. n p2 is an integer of 0 to 10. n p3 is an integer of 0 to 10. Here, n p1 +n p2 +n p3 is an integer of 1 or more and 30 or less. When n p1 is 2 or more, the multiple R p2 s are the same or different. When n p2 is 2 or greater, a plurality of R p3 are the same or different, and a plurality of R p4 are the same or different. When n p3 is 2 or greater, multiple R p5 are the same or different, and multiple R p6 are the same or different. Z + is a monovalent onium cation.

2. In A of the above formula (1), L α -OR to a carbon atom other than the carbon atom adjacent to the carbon atom to which Ｙ The radiation-sensitive resin composition according to claim 1 , wherein:

3. -R in the above formula (1) Ｙ 3. The radiation-sensitive resin composition according to claim 1, wherein: is a hydrogen atom.

4. 4. The radiation-sensitive resin composition according to claim 1, wherein the aromatic hydrocarbon group is a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group or a pyrenyl group.

5. The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the structural unit represented by the above formula (1) is a structural unit represented by any one of the following formulas (1-1) to (1-4): 【Chemistry 3】 (In the formula, R Ｘ , R Ｙ and L α has the same meaning as formula (1) above. R ａ１ , R ａ２ , R ａ３ and R ａ４ are each independently a cyano group, a nitro group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group. n1 is an integer from 0 to 4. n2, n3, and n4 are each independently an integer from 0 to 6. R ａ１ , R ａ２ , R ａ３ and R ａ４ If there are multiple of each, there are multiple R ａ１ , R ａ２ , R ａ３ and R ａ４ are the same or different.)

6. The above L α 6. The radiation-sensitive resin composition according to claim 1, wherein: is a single bond.

7. The radiation-sensitive resin composition according to any one of claims 1 to 6, wherein the resin further contains a structural unit C represented by the following formula (cf): 【Chemistry 4】 (In the formula, R ＣＦ１ is a hydrogen atom or a methyl group. R ＣＦ２ is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. n ｆ１ is an integer from 0 to 3. ｆ１ When is 2 or 3, multiple R ＣＦ２ are the same or different. ｆ２ is an integer from 1 to 3. ｆ１ +n ｆ２ is 5 or less. ａｆ is an integer from 0 to 2.)

8. The radiation-sensitive resin composition according to any one of claims 1 to 7, wherein the acid-dissociable group has a monocyclic or polycyclic alicyclic structure.

9. 9. The radiation-sensitive resin composition according to claim 1, further comprising an onium salt compound that, upon irradiation with radiation, generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator.

10. 10. The radiation-sensitive resin composition according to any one of claims 1 to 9, wherein the content of the structural unit represented by the formula (1) is 5 mol % or more and 70 mol % or less based on the total content of the structural units constituting the resin.

11. A step of forming a resist film from the radiation-sensitive resin composition according to any one of claims 1 to 10; a step of exposing the resist film to light; and A method for forming a resist pattern comprising the step of developing the exposed resist film.

12. 12. The method for forming a resist pattern according to claim 11, wherein the exposure is carried out using extreme ultraviolet rays or electron beams.

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