Radiation-sensitive resin composition and pattern-forming method

Abstract

Provided are a radiation-sensitive resin composition and a pattern formation method by which sensitivity, critical dimension uniformity (CDU) performance, and development residue performance can be exhibited on a sufficient level when next-generation technology is applied.　The radiation-sensitive resin composition comprises: a radiation-sensitive acid-generating resin including a structural unit A having an acid-dissociable group, and a structural unit D having a phenolic hydroxy group; and a solvent. The structural unit D has a phenolic hydroxy group and an alkyl group on the same aromatic ring, and in the aromatic ring of the structural unit D, the alkyl group is bonded to a carbon atom adjacent to the carbon atom to which the phenolic hydroxy group is bonded.　The radiation-sensitive resin composition further satisfies at least one condition selected from the group consisting of the following conditions 1 and 2.　Condition 1: The resin is a radiation-sensitive acid-generating resin further including a structural unit B including an organic acid anion moiety, and an onium cation moiety including an aromatic ring structure having a fluorine atom.　Condition 2: An onium salt (excluding the radiation-sensitive acid-generating resin) including an organic acid anion moiety and an onium cation including an aromatic ring structure having a fluorine atom is further provided.

Description

[Technical Field]

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

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, irradiating a resist film with radiation through a mask pattern to generate acid, and then using this acid as a catalyst to create a difference in solubility in the developer between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] The above-mentioned photolithography techniques utilize short-wavelength radiation such as ArF excimer lasers, or combine this radiation with liquid immersion lithography to advance pattern miniaturization. As a next-generation technology, efforts are being made to utilize even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) radiation, and resist materials containing acid generators with benzene rings that enhance the absorption efficiency of such radiation are also being investigated (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-2359 [Overview of the project] [Problems that the invention aims to solve]

[0005] Even with the aforementioned next-generation technologies, the resist performance is required to be equal to or better than conventional methods in terms of sensitivity, critical dimension uniformity (CDU) performance (an indicator of the uniformity of line width and hole diameter), and the amount of development residue.

[0006] The present invention aims to provide a radiation-sensitive resin composition and a pattern-forming method that can exhibit sufficient levels of sensitivity, CDU performance, and development residue performance when next-generation technologies are applied. [Means for solving the problem]

[0007] The inventors of this invention conducted extensive research to solve this problem and, as a result, found that the above objective can be achieved by adopting the following configuration, thus completing the present invention.

[0008] In one embodiment, the present invention is A resin comprising structural unit A having an acid-dissociable group and structural unit D having a phenolic hydroxyl group, Solvent and Includes, The above structural unit D has a phenolic hydroxyl group and an alkyl group on the same aromatic ring, This invention relates to a radiation-sensitive resin composition in which, in the aromatic ring of the above structural unit D, an alkyl group is bonded to a carbon atom adjacent to the carbon atom to which a phenolic hydroxyl group is bonded. However, the above radiation-sensitive resin composition further satisfies at least one selected from the group consisting of the following conditions 1 and 2. Condition 1: The above resin is a radiation-sensitive acid-generating resin that further includes structural unit B, which comprises an organic acid anion moiety and an onium cation moiety having an aromatic ring structure with a fluorine atom. Condition 2: Further comprises an onium salt (excluding the above-mentioned radiation-sensitive acid-generating resin) containing an organic acid anion moiety and an onium cation moiety containing an aromatic ring structure having a fluorine atom.

[0009] The radiation-sensitive resin composition in question allows for the construction of a resist film that satisfies the requirements for sensitivity, CDU performance, and developer residue performance. Although the reason for this is not entirely clear, it is presumed that the following is the case: The absorption of radiation such as EUV at a wavelength of 13.5 nm by fluorine atoms is very large, which makes the radiation-sensitive resin composition highly sensitive. In addition, the acid-dissociable groups of structural unit A in the resin have a high acid-dissociation efficiency upon exposure, which increases the contrast between exposed and unexposed areas and results in excellent pattern formation. It is presumed that the above-mentioned resist performance can be achieved through the combined effects of these factors.

[0010] In another embodiment, the present invention is A step of applying the radiation-sensitive resin composition directly or indirectly onto a substrate to form a resist film, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. This relates to a pattern formation method that includes [specific details].

[0011] This pattern formation method uses the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity, CDU performance, and development residue performance, thus enabling the efficient formation of high-quality resist patterns. [Modes for carrying out the invention]

[0012] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0013] <Radiation sensitive resin composition>

[0014] The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "the composition") comprises a resin and a solvent. The composition may contain other optional components as long as they do not impair the effects of the present invention. By including a predetermined resin, the radiation-sensitive resin composition can impart a high level of sensitivity, CDU performance, and developer residue performance to the resulting resist film.

[0015] <Resin> The resin is either an aggregate of polymers (G1) comprising structural unit A having an acid-dissociable group, structural unit B comprising an onium cation moiety containing an organic acid anion moiety and an aromatic ring structure having a fluorine atom, and structural unit D having a phenolic hydroxyl group, or an aggregate of polymers (G2) comprising structural unit A having an acid-dissociable group and structural unit D having a phenolic hydroxyl group, or an aggregate containing both aggregates (G1) and (G2) (hereinafter, these polymers (G1) and (G2) are also referred to as the "base resin"). In aggregates (G1) and (G2), structural unit D has a phenolic hydroxyl group and an alkyl group on the same aromatic ring, and in the aromatic ring of structural unit D, the alkyl group is bonded to the carbon atom adjacent to the carbon atom to which the phenolic hydroxyl group is bonded. In addition to structural units A, B, and D, the base resin may also contain structural unit E containing a lactone structure or other structural units. Each structural unit will be described below.

[0016] (Structural Unit A) Structural unit A (hereinafter also referred to as "structural unit A") is preferably a structural unit represented by the following formula (1).

[0017] [ka] (In the above formula (1), R T These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R X It is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Cy represents an alicyclic structure with 3 to 20 members, formed together with the carbon atoms to which it is bonded.

[0018] R X Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by this formula, include chain hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0019] Examples of the above-mentioned chain-like hydrocarbon groups having 1 to 10 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 2 to 10 carbon atoms.

[0020] Examples of the above-mentioned alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are linked by a linking group containing one or more carbon atoms.

[0021] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthyl groups; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0022] R X Preferred examples include linear or branched saturated hydrocarbon groups having 1 to 5 carbon atoms, alicyclic hydrocarbon groups having 3 to 12 carbon atoms, and aromatic hydrocarbon groups having 6 to 10 carbon atoms. In the case of aromatic hydrocarbon groups having 6 to 10 carbon atoms, an embodiment in which some of the hydrogen atoms of the aromatic hydrocarbon group are substituted with halogen atoms is also preferred.

[0023] The alicyclic structure having 3 to 20 ring members in Cy is not particularly limited as long as it has an alicyclic structure, and may have a monocyclic, bicyclic, tricyclic, tetracyclic or higher polycyclic structure, and may be a bridged ring structure, a spiro ring structure, a ring assembly structure in which a plurality of rings are directly bonded by a single bond or a double bond, or any combination thereof. Among them, it is preferably a monocyclic, bicyclic, tricyclic or tetracyclic bridged ring structure, such as a monocyclic cycloalkyl ring structure such as cyclopentane and cyclohexane; norbornane, adamantane, tricyclo[5.2.1.0 2,6 decane, tetracyclo[4.4.0.1 2,5 .1 7,10 dodecane, perhydronaphthalene, perhydroanthracene and other polycyclic cycloalkyl ring structures are more preferable.

[0024] The structural unit represented by the above formula (1) is preferably represented by, for example, the following formulas (A-1) to (A-8).

[0025]

Chemical formula

[0026] In the above formulas (A-1) to (A-8), R T and R X have the same meaning as in the above formula (1). Among them, the structural unit A is preferably represented by, for example, the above formulas (A-1), (A-4), (A-5), (A-6), (A-8).

[0027] The structural unit A is also preferably a structural unit represented by the following formula (4).

[0028]

Chemical formula

[0029] R c From the viewpoint of copolymerizability of the monomer that gives the structural unit represented by formula (4), a hydrogen atom or a methyl group is preferred.

[0030] L c Examples of divalent linking groups represented by include alkanediyl groups, cycloalkanediyl groups, alkenediyl groups, arylene groups, and -OR groups. LA - * ,-COOR LB - * Examples include (* indicates a bond on the carbonyl group side).

[0031] As the above alkanediyl group, an alkanediyl group having 1 to 8 carbon atoms is preferred.

[0032] Examples of the above-mentioned cycloalkanediyl groups include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups, and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. A cycloalkanediyl group having 5 to 12 carbon atoms is preferred.

[0033] Examples of the alkenediyl group mentioned above include ethendiyl group, propenediyl group, and butenediyl group. A preferred alkenediyl group is one having 2 to 6 carbon atoms.

[0034] The above - OR LA - * R LA Examples include the above-mentioned alkanediyl group, cycloalkanediyl group, and alkenediyl group. (The above-mentioned -COOR) LB - * R LBExamples of these groups include the alkanediyl group, cycloalkanediyl group, alkenediyl group, and arenediyl group. Examples of arenediyl groups include benzenediyl group, torylene group, and naphthalenediyl group. Among the above arenediyl groups, arenediyl groups having 6 to 15 carbon atoms are preferred.

[0035] Among these, L c is a single bond or -COOR LB - * It is preferable that this is the case. LB An alkanediyl group is preferred as the group.

[0036] L c Some or all of the hydrogen atoms on the carbon atoms inside may be substituted with halogen atoms such as fluorine or chlorine atoms, alkyl halogens such as trifluoromethyl groups, alkoxy groups such as methoxy groups, cyano groups, etc.

[0037] R c1 , R c2 and R c3 As a monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1), R X Groups such as the monovalent hydrocarbon group with 1 to 20 carbon atoms represented by can be used.

[0038] Among them, R c1 and R c2 However, each is independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, and R c3 It is preferable that R is a monovalent alicyclic or aromatic hydrocarbon group having 6 to 12 carbon atoms. c1 , R c2 and R c3 It is also preferable that each of these be independently a monovalent chain hydrocarbon group having 1 to 12 carbon atoms.

[0039] The structural unit represented by formula (4) is preferably represented by the following formulas (4-1) to (4-18).

[0040] [ka]

[0041] [ka]

[0042] In the above equations (4-1) to (4-18), R c This is equivalent to formula (4) above. In particular, structural unit (II) is preferably represented by formulas (4) to (4 to 3) and (4 to 10) to (4 to 12) above.

[0043] The content of structural unit A in the resin (total if multiple types of structural unit A exist) is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to the total structural units constituting the resin. The above content is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. By setting the content of structural unit A within the above range, the radiation-sensitive resin composition can achieve further improvements in sensitivity and CDU performance.

[0044] (Structural Unit B) Structural unit B (hereinafter also referred to as "structural unit B") is a structural unit comprising an organic acid anion moiety and an onium cation moiety containing an aromatic ring structure having a fluorine atom. In other words, structural unit B comprises an organic acid anion moiety and an onium cation moiety, and the onium cation moiety contains an aromatic ring structure having a fluorine atom.

[0045] The above structural unit B is derived from a monomer containing a structure that decomposes upon exposure and generates acid. Therefore, a resin containing structural unit B functions as a radiation-sensitive acid-generating resin. Examples of onium cations in structural unit B include sulfonium cations and iodonium cations.

[0046] In the above structural unit B, a sulfonium cation is preferred as the onium cation, and the monomer that gives such structural unit B is preferably a structural unit derived from, for example, the monomer represented by formula (2) or the monomer represented by formula (3) below.

[0047] [ka] (In equations (2) and (3) above, R A and R B These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R Y and R Z Each is independently a hydrogen atom, a fluorine atom, or a fluorinated hydrocarbon group, and at least one is a fluorine atom or a fluorinated hydrocarbon group. Y and R Z They may be the same or different. s is an integer between 1 and 20. R 1 ~R 3 It is independently a monovalent hydrocarbon group and an aromatic ring having at least one fluorine atom. R 4 ~R 6 It is independently a monovalent hydrocarbon group and an aromatic ring having at least one fluorine atom. Y 1 This is a single bond, or -Y 11 -C(=O)-O- Y 11 This refers to a divalent hydrocarbon group having 1 to 20 carbon atoms or a divalent hydrocarbon group having 1 to 20 carbon atoms containing a heteroatom. Y 2 This includes a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, and -OY 21 -, -C(=O)-OY 21 -or -C(=O)-NH-Y 21 - is Y 21This group is an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms, or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. The alkanediyl group having 1 to 6 carbon atoms, the alkenediyl group having 2 to 6 carbon atoms, and the phenylene group may be substituted with a fluorine atom.

[0048] In equations (2) and (3), R Y and R Z Each is independently a hydrogen atom, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms, and at least one is a fluorine atom or a fluorinated hydrocarbon group. The hydrocarbon group constituting the above monovalent fluorinated hydrocarbon group may be linear, branched, or cyclic, and specific examples include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, and tert-butyl group; cycloalkyl groups such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, and adamantyl group; alkenyl groups such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group, and cyclohexenyl group; aryl groups such as phenyl group, naphthyl group, and thienyl group; and aralkyl groups such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group. Examples of monovalent fluorinated hydrocarbon groups include those in which some or all of the hydrogen atoms of these hydrocarbon groups are substituted with fluorine-containing groups. Y and R Z They may be the same or different.

[0049] In formula (2), Y 1 ga-Y 11 If -C(=O)-O-, then Y 11Divalent hydrocarbon groups having 1 to 20 carbon atoms that may contain heteroatoms represented by the formula shown below include, but are not limited to, the following. Furthermore, the hydrogen atoms in the structures shown below may be substituted with substituents containing heteroatoms. Such substituents include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), carboxyl groups, hydroxyl groups, thiol groups, and amino groups. Among these, Y 11 It is preferable that it is a divalent aromatic hydrocarbon group containing iodine.

[0050] [ka] (In the formula, the dashed lines represent the bonds between the oxygen atom and the carbon atom in formula (2).)

[0051] Examples of organic acid anion moieties of monomers that give structural unit B are, but are not limited to, those listed below. While all of the examples below are organic acid anion moieties having an iodine-substituted aromatic ring structure, for organic acid anion moieties that do not have an iodine-substituted aromatic ring structure, structures in which the iodine atom in the following formula is replaced with a hydrogen atom or other substituent or other atom or group can be suitably adopted.

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] In equations (2) and (3), R 1 ~R 3 R is independently a monovalent hydrocarbon group and an aromatic ring having at least one fluorine atom. 4 ~R 6 R is independently a monovalent hydrocarbon group and an aromatic ring having at least one fluorine atom. In this specification, "aromatic ring having a fluorine atom" refers to a structure in which some or all of the hydrogen atoms in the aromatic ring are replaced by fluorine atoms or fluorinated hydrocarbon groups (preferably perfluorohydrocarbon groups). The monovalent hydrocarbon group may be linear, branched, or cyclic, and a specific example thereof is R Y and R Z The hydrocarbon groups that constitute the fluorinated hydrocarbon group in are similar to those listed above, and are preferably aryl groups. Furthermore, some of the hydrogen atoms in these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms. 1 ~R 3 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded, R 4 ~R 6 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0058] The onium cation portion in formulas (2) and (3) is preferably represented by the following formula (Q-1).

[0059] [ka]

[0060] In the above formula (Q-1), Ra1 and Ra2 each independently represent substituents. n1 represents an integer from 0 to 5, and if n1 is 2 or greater, multiple Ra1s may be the same or different. n2 represents an integer from 0 to 5, and if n2 is 2 or greater, multiple Ra2s may be the same or different. n3 represents an integer from 1 to 5, and if n3 is 2 or greater, multiple Ra3s may be the same or different. Ra3 represents a fluorine atom or a group having one or more fluorine atoms. If n1 is 2 or greater, multiple Ra1s may be linked to each other to form a ring. If n2 is 2 or greater, multiple Ra2s may be linked to each other to form a ring. If n1 is 1 or greater and n2 is 1 or greater, Ra1 and Ra2 may be linked to each other to form a ring (i.e., a heterocycle containing a sulfur atom).

[0061] Preferred substituents represented by Ra1 and Ra2 are alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkyloxy groups, alkoxycarbonyl groups, alkylsulfonyl groups, cycloalkylsulfonyl groups, hydroxyl groups, halogen atoms, and halogenated hydrocarbon groups.

[0062] The alkyl groups Ra1 and Ra2 may be linear or branched. Preferably, these alkyl groups have 1 to 10 carbon atoms; for example, R Y and R Z The hydrocarbon groups that make up the fluorinated hydrocarbon group in the above are similar to those listed above. Of these, methyl, ethyl, n-butyl, and t-butyl groups are particularly preferred.

[0063] Examples of cycloalkyl groups for Ra1 and Ra2 include monocyclic or polycyclic cycloalkyl groups (preferably cycloalkyl groups having 3 to 20 carbon atoms), such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecanyl, cyclopentenyl, cyclohexenyl, and cyclooctadienyl groups. Of these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups are particularly preferred.

[0064] Examples of the alkyl groups of the alkoxy groups of Ra1 and Ra2 include those listed above as alkyl groups of Ra1 and Ra2. Methoxy, ethoxy, n-propoxy, and n-butoxy groups are particularly preferred as alkoxy groups.

[0065] Examples of the cycloalkyl group portions of the cycloalkyloxy groups of Ra1 and Ra2 include those previously listed as cycloalkyl groups of Ra1 and Ra2. Cyclopentyloxy and cyclohexyloxy groups are particularly preferred as these cycloalkyloxy groups.

[0066] Examples of the alkoxy group portion of the alkoxycarbonyl groups of Ra1 and Ra2 include those previously listed as alkoxy groups of Ra1 and Ra2. Methoxycarbonyl groups, ethoxycarbonyl groups, and n-butoxycarbonyl groups are particularly preferred as alkoxycarbonyl groups.

[0067] Examples of the alkyl group portion of the alkylsulfonyl groups of Ra1 and Ra2 include those previously listed as alkyl groups of Ra1 and Ra2. Similarly, examples of the cycloalkyl group portion of the cycloalkylsulfonyl groups of Ra1 and Ra2 include those previously listed as cycloalkyl groups of Ra1 and Ra2. Among these alkylsulfonyl groups or cycloalkylsulfonyl groups, methanesulfonyl group, ethanesulfonyl group, n-propanesulfonyl group, n-butanesulfonyl group, cyclopentanesulfonyl group, and cyclohexanesulfonyl group are particularly preferred.

[0068] Each of the Ra1 and Ra2 groups may have further substituents. Examples of these substituents include halogen atoms such as fluorine atoms (preferably fluorine atoms), hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxy groups, cycloalkyloxy groups, alkoxyalkyl groups, cycloalkyloxyalkyl groups, alkoxycarbonyl groups, cycloalkyloxycarbonyl groups, alkoxycarbonyloxy groups, and cycloalkyloxycarbonyloxy groups.

[0069] Examples of halogen atoms for Ra1 and Ra2 include fluorine, chlorine, bromine, and iodine atoms, with fluorine and iodine atoms being preferred.

[0070] As the halogenated hydrocarbon groups of Ra1 and Ra2, halogenated alkyl groups are preferred. The alkyl groups and halogen atoms constituting the halogenated alkyl groups are the same as those described above. Among these, fluorinated alkyl groups are preferred, and CF3 is more preferred.

[0071] As described above, Ra1 and Ra2 may be linked to each other to form a ring (i.e., a heterocycle containing a sulfur atom). In this case, it is preferable that Ra1 and Ra2 bond to each other to form a single bond or a divalent linking group. Examples of divalent linking groups include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO2-, alkylene groups, cycloalkylene groups, alkenylene groups, or combinations of two or more of these, and it is preferable that the total number of carbon atoms is 20 or less. When Ra1 and Ra2 are linked to each other to form a ring, it is preferable that Ra1 and Ra2 bond to each other to form -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO2-, or a single bond. Among these, it is more preferable to form -O-, -S-, or a single bond, and it is particularly preferable to form a single bond. Also, when n1 is 2 or more, multiple Ra1s may be linked to each other to form a ring, and when n2 is 2 or more, multiple Ra2s may be linked to each other to form a ring. One example of this is a configuration in which two Ra1 molecules are linked to each other and, together with the benzene ring to which they are bonded, form a naphthalene ring.

[0072] Ra3 is a fluorine atom or a group having one or more fluorine atoms. Examples of groups having fluorine atoms include alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkyloxy groups, alkoxycarbonyl groups, and alkylsulfonyl groups, where Ra1 and Ra2 are substituted with fluorine atoms. Among these, fluorinated alkyl groups are particularly preferred, such as CF3, C2F5, C3F7, C4F9, and C5F 11 , C6F 13 , C7F 15 , C8F 17 CH2CF3, CH2CH2CF3, CH2C2F5, CH2CH2C2F5, CH2C3F7, CH2CH2C3F7, CH2C4F9 and CH2CH2C4F9 can be further preferred, and CF3 can be particularly preferred.

[0073] Ra3 is preferably a fluorine atom or CF3, and more preferably a fluorine atom.

[0074] n3 is preferably 1 to 3, and more preferably 1 or 2.

[0075] (n1+n2+n3) is preferably 1 to 15, more preferably 1 to 9, even more preferably 2 to 6, and particularly preferably 3 to 6. When (n1+n2+n3) is 1, it is preferable that n3=1 and Ra3 is a fluorine atom or CF3. When (n1+n2+n3) is 2, it is preferable that n1=n3=1 and Ra1 and Ra3 are each independently a fluorine atom or CF3, and that n3=2 and Ra3 is a fluorine atom or CF3. When (n1+n2+n3) is 3, it is preferable that n1=n2=n3=1 and Ra1 to Ra3 are each independently a fluorine atom or CF3. (n1+n 2+When n3) is 4, the combination n1=n3=2 and Ra1 and Ra3 are each independently fluorine atoms or CF3 is preferred. When (n1+n2+n3) is 5, the combinations n1=n2=1 and n3=3 and Ra1~Ra3 are each independently fluorine atoms or CF3, the combination n1=n2=2 and n3=1 and Ra1~Ra3 are each independently fluorine atoms or CF3, and the combination n3=5 and Ra3 are each independently fluorine atoms or CF3 are preferred. When (n1+n2+n3) is 6, the combination n1=n2=n3=2 and Ra1~Ra3 are each independently fluorine atoms or CF3 is preferred.

[0076] A specific example of the onium cation portion represented by the above formula (Q-1) is the onium cation in onium salts, which will be discussed later.

[0077] As the onium cation in structural unit B, diaryliodonium cations having one or more fluorine atoms are also preferred.

[0078] Specific examples of diaryliodonium cations having one or more fluorine atoms include the following. While all of the examples below are iodonium cation moieties containing an aromatic ring structure with a fluorine atom, structures in which the fluorine atom is replaced with a fluorinated hydrocarbon group such as a trifluoromethyl group can also be suitably adopted.

[0079] [ka]

[0080] The content of structural unit B in the resin (total if multiple types of structural unit B exist) is preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 4 mol% or more, and particularly preferably 5 mol% or more, relative to the total structural units constituting the resin. Furthermore, 30 mol% or less is preferred, 25 mol% or less is more preferred, 20 mol% or less is even more preferred, and 15 mol% or less is particularly preferred. By setting the content within this range, the resin can fully exhibit its function as a radiation-sensitive acid-generating resin.

[0081] (Structural Unit D) Structural unit D is a structural unit having a phenolic hydroxyl group, having both a phenolic hydroxyl group and an alkyl group on the same aromatic ring, and in the aromatic ring, the alkyl group is bonded to the carbon atom adjacent to the carbon atom to which the phenolic hydroxyl group is bonded. In other words, structural unit D is a structural unit having a phenolic hydroxyl group, to which an alkyl group is further bonded to the aromatic ring to which the phenolic hydroxyl group is bonded, and the carbon atom to which the phenolic hydroxyl group is bonded and the carbon atom to which the alkyl group is bonded are directly connected. In the present invention, phenolic hydroxyl groups produced by deprotection due to the action of acids generated by exposure are also included as phenolic hydroxyl groups of structural unit D. Although the reason why the resin containing structural unit D produces the effects of the present invention is not clear, one possibility is as follows: The phenolic hydroxyl groups of the resin may interact with the onium cation moiety of the radiation-sensitive acid-generating resin or the onium cation of the onium salt, which may worsen development defects. On the other hand, it is speculated that the presence of alkyl groups near the phenolic hydroxyl groups of the resin weakens the interaction due to steric hindrance, resulting in improved development defects. Furthermore, when using radiation such as KrF excimer laser light, EUV, or electron beams as the radiation irradiated in the exposure step of the resist pattern formation method, structural unit D contributes to improved etching resistance and improved difference in developer solubility (dissolution contrast) between the exposed and unexposed areas. In particular, it can be suitably applied to pattern formation using exposure with radiation of wavelengths of 50 nm or less, such as electron beams and EUV. Structural unit D is preferably represented by the following formula (D).

[0082] [Chemical] (In the above formula (D), R α is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L CA is a single bond, -COO- * or -O-. * is a bond on the aromatic ring side. R 101 is a hydrogen atom or a protecting group that is deprotected by the action of an acid to become a hydrogen atom. When there are a plurality of R 101 s, the plurality of R 101 s are the same as or different from each other. However, at least one R 101 is a hydrogen atom. R 102 is a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group or an acyloxy group. However, at least one R 102 is an alkyl group. n d3 is an integer from 0 to 2, m d3 is an integer from 1 to 8, and m4 is an integer from 1 to 8. However, 1 ≤ m d3 + m4 ≤ 2n d3 + 5 is satisfied. In formula (D), R 102 is bonded to the carbon atom adjacent to the carbon atom to which the phenolic hydroxyl group is bonded, and the R 102 is an alkyl group.)

[0083] As the above R α [, from the perspective of the copolymerizability of the monomer that gives the structural unit D, it is preferably a hydrogen atom or a methyl group.

[0084] L CA is preferably a single bond or -COO- * .

[0085] The above R 101 ​Examples of protecting groups that are deprotected by the action of an acid represented by the formula (AL-1) to (AL-3) below include the groups represented by the following formulas.

[0086] [ka]

[0087] In the above formulas (AL-1) and (AL-2), R M1 and R M2 is a monovalent hydrocarbon group, which may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The monovalent hydrocarbon group may be linear, branched, or cyclic, and an alkyl group having 1 to 40 carbon atoms is preferred, with an alkyl group having 1 to 20 carbon atoms being more preferred. In formula (AL-1), a is an integer from 0 to 10, and an integer from 1 to 5 is preferred. In formulas (AL-1) to (AL-3), * represents a bond with another part.

[0088] In the above formula (AL-2), R M3 and R M4 Each of these is independently a hydrogen atom or a monovalent hydrocarbon group, and may contain heteroatoms such as oxygen, sulfur, nitrogen, or fluorine atoms. The monovalent hydrocarbon group may be linear, branched, or cyclic, and alkyl groups having 1 to 20 carbon atoms are preferred. Also, R M2 , R M3 and R M4 Any two of these may bond with each other to form a ring with 3 to 20 carbon atoms, together with the carbon atom to which they are bonded or with an oxygen atom. A ring with 4 to 16 carbon atoms is preferred.

[0089] In the above formula (AL-3), R M5 , R M6 and R M7 Each of these is independently a monovalent hydrocarbon group and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The above monovalent hydrocarbon group may be linear, branched, or cyclic, and alkyl groups having 1 to 20 carbon atoms are preferred. Also, R M5 , RM6 and R M7 Any two of these may bond with each other to form a ring with 3 to 20 carbon atoms. A ring with 5 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0090] Among these, the group represented by the above formula (AL-3) is preferred as a protecting group that is deprotected by the action of an acid.

[0091] R 102 Examples of alkyl groups include linear or branched alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, and propyl groups. Examples of fluorinated alkyl groups include linear or branched fluorinated alkyl groups having 1 to 8 carbon atoms, such as trifluoromethyl and pentafluoroethyl groups. Examples of alkoxycarbonyloxy groups include linear or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as methoxycarbonyloxy, butoxycarbonyloxy, and adamantylmethyloxycarbonyloxy. Examples of acyl groups include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as acetyl, propionyl, benzoyl, and acryloyl groups. Examples of acyloxy groups include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as acetyloxy, propionyloxy, benzoyloxy, and acryloyloxy.

[0092] The above d3 0 or 1 is more preferable, and 0 is even more preferable.

[0093] The above m d3 Preferably, the integer is between 1 and 3, and more preferably 1 or 2.

[0094] For the above m4, an integer between 1 and 3 is preferred, and an integer between 1 and 2 is more preferred.

[0095] In the aromatic ring of the above structural unit D, an alkyl group may be bonded to only one of the carbon atoms adjacent to the carbon atom to which the phenolic hydroxyl group is bonded, or both carbon atoms may be bonded to an alkyl group. If an alkyl group is bonded to only one of the carbon atoms adjacent to the carbon atom to which the phenolic hydroxyl group is bonded, the other carbon atom is L CA It is bonded to the main chain of the resin, is unsubstituted (i.e., bonded to a hydrogen atom), or is bonded to a substituent other than an alkyl group.

[0096] In the aromatic ring of the above structural unit D, the alkyl group bonded to the carbon atom adjacent to the carbon atom to which the phenolic hydroxyl group is bonded is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a linear or branched alkyl group having 1 to 3 carbon atoms, even more preferably a methyl group, an ethyl group, or an isopropyl group, and particularly preferably a methyl group.

[0097] Examples of monomers that give such a structural unit D include 3-alkyl-4-hydroxystyrene, 3,5-dialkyl-4-hydroxystyrene, 3-alkyl-4-hydroxy-5-iodostyrene, 3,4-dihydroxy-5-alkylstyrene, 4-alkyl-3-hydroxystyrene, 2,4-dialkyl-3-hydroxystyrene, 3-alkyl-2-hydroxystyrene, 3-alkyl-4-hydroxyphenyl(meth)acrylate, 3,5-dialkyl-4-hydroxyphenyl(meth)acrylate, 3-alkyl-4-hydroxy-5-iodophenyl(meth)acrylate, 3,4-dihydroxy-5-alkylphenyl(meth)acrylate, 4-alkyl-3-hydroxyphenyl(meth)acrylate, 2,4-dialkyl-3-hydroxyphenyl(meth)acrylate, and 3-alkyl-2-hydroxyphenyl(meth)acrylate. Among these, 3-alkyl-4-hydroxystyrene, 3,5-dialkyl-4-hydroxystyrene, 3-alkyl-4-hydroxyphenyl (meth)acrylate, and 3,5-dialkyl-4-hydroxyphenyl (meth)acrylate are preferred. When these monomers have two or more alkyl groups, the multiple alkyl groups may be the same or different.

[0098] The structural unit D is preferably a structural unit represented by the following formulas (D-1) to (D-10) (hereinafter also referred to as "structural unit (D-1) to structural unit (D-10)").

[0099] [ka]

[0100] In the above equations (D-1) to (D-10), R α This is the same as equation (D) above.

[0101] Among these, the above structural units (D-1) to (D-2), (D-5), and (D-8) to (D-10) are preferred.

[0102] The content of structural unit D (total if multiple types of structural unit D exist) is preferably 5 mol% or more, more preferably 8 mol% or more, even more preferably 10 mol% or more, and particularly preferably 15 mol% or more, relative to the total structural units constituting the resin. The above content is preferably 60 mol% or less, more preferably 50 mol% or less, even more preferably 40 mol% or less, and particularly preferably 35 mol% or less. By setting the content of structural unit D within the above range, the above radiation-sensitive resin composition can achieve further improvements in sensitivity, CDU performance, and resolution.

[0103] Furthermore, the content of structural unit D (total if multiple types of structural unit D exist) is preferably 15 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and particularly preferably 65 mol% or more, relative to all structural units having a phenolic hydroxyl group.

[0104] When polymerizing monomers having phenolic hydroxyl groups, such as 3-alkyl-hydroxystyrene, it is preferable to polymerize them while protecting the phenolic hydroxyl groups with protecting groups such as alkali-dissociable groups, and then deprotect them by hydrolysis to obtain structural unit D.

[0105] (Structural Unit E) Structural unit E is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. By further comprising structural unit E, the solubility of the base resin in the developer can be adjusted, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. Furthermore, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0106] When structural unit E is included, the content of structural unit E is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, relative to the total structural units constituting the base resin. The above content is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 40 mol% or less. By setting the content of structural unit E within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0107] The base resin of the present invention may contain structural units other than structural units A, B, D, and E. Examples of such other structural units include structural units having phenolic hydroxyl groups such as hydroxystyrene and hydroxyphenyl (meth)acrylate (excluding structural unit D); structural units having aliphatic hydrocarbon groups such as alkyl (meth)acrylate (excluding structural unit A); structural units having alicyclic hydrocarbon groups such as cycloalkyl (meth)acrylate and adamantyl (meth)acrylate (excluding structural unit A); and structural units having aromatic hydrocarbon groups such as styrene, phenyl (meth)acrylate, and iodostyrene.

[0108] The base resin of the present invention preferably contains an iodine-substituted aromatic ring structure. The iodine-substituted aromatic ring structure of the base resin may be contained in any of structural units A to E, or in structural units other than structural units A to E. It is more preferable that it be contained in one or more of structural units A, B, and D. An example of a structural unit other than structural units A to E containing an iodine-substituted aromatic ring structure is a structural unit derived from iodostyrene. The content ratio of the iodine-substituted aromatic ring structure is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 3 mol% or more, relative to the total structural units constituting the base resin. The above content ratio is preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less. By setting the content ratio of the iodine-substituted aromatic ring structure within the above range, the lithography performance such as CDU performance of the radiation-sensitive resin composition can be further improved.

[0109] (Method of resin synthesis) The base resin can be synthesized, for example, by carrying out a polymerization reaction in a suitable solvent using monomers that provide each structural unit, with known radical polymerization initiators or the like.

[0110] The molecular weight of the base resin is not particularly limited, but the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 4,000 or more. Furthermore, it is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 15,000 or less, and particularly preferably 12,000 or less. If the Mw of the resin is within the above range, the resulting resist film will have good heat resistance and developability.

[0111] The ratio of Mw (Mw / Mn) to the polystyrene-equivalent number-average molecular weight (Mn) of the base resin, as determined by GPC, is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0112] In this specification, the Mw and Mn values ​​of the resin are measured using gel permeation chromatography (GPC) under the following conditions. GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Leaching 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

[0113] The resin content is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, relative to the total solid content of the above-mentioned radiation-sensitive resin composition.

[0114] <Other resins> The radiation-sensitive resin composition of this embodiment may also contain, as another resin, a resin with a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface of the resist film relative to the base resin, and as a result, the state of the resist film surface can be controlled to a desired state.

[0115] As a high-fluorine-content resin, for example, it is preferable to have, as necessary, one or more of the structural units A to E in the base resin, as well as a structural unit represented by the following formula (f0) (hereinafter also referred to as "structural unit F").

[0116] [ka]

[0117] In the above equation (f0), R 13 This is a hydrogen atom, a methyl group, or a trifluoromethyl group. L R is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. 14 This is 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.

[0118] The above R 13 From the viewpoint of copolymerization of monomers that give structural unit F, hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0119] The above G L From the viewpoint of copolymerization of monomers that give structural unit F, single bonds and -COO- are preferred, and -COO- is more preferred.

[0120] The above R 14Examples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0121] The above R 14 Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0122] The above R 14 Preferably, the group is a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a 5,5,5-trifluoro-1,1-diethylpentyl group, and a 1,1,1,2,2,3,3-heptafluoro-6-methylheptan-4-yl group.

[0123] When a high-fluorine-content resin has structural unit F, the content of structural unit F is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, the above content is preferably 100 mol% or less, more preferably 95 mol% or less, and even more preferably 90 mol% or less. By setting the content of structural unit F within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting the uneven distribution of fluorine atoms on the surface of the resist film.

[0124] High-fluorine-content resins may have structural units other than structural unit F. Examples of other structural units include structural unit G, which has an alcoholic hydroxyl group to which a fluorinated hydrocarbon group is bonded to the carbon atom to which the alcoholic hydroxyl group is bonded; and structural unit H, which contains at least one atom selected from the group consisting of iodine and bromine atoms. Structural unit H more preferably contains an aromatic ring structure substituted with an iodine atom.

[0125] When the high-fluorine-content resin has structural unit G, the content of structural unit G is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. The above content is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less. When the high-fluorine-content resin has structural unit H, the content of structural unit H is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, relative to the total structural units constituting the high-fluorine-content resin. The above content is preferably 40 mol% or less, more preferably 30 mol% or less, and even more preferably 20 mol% or less. By setting the content ratios of structural unit G and structural unit H within the above ranges, the resist film surface can be controlled to a desired state.

[0126] For high-fluorine-content resins, Mw is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 5,000 or more. For the above Mw, 50,000 or less is preferred, more preferably 30,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less.

[0127] The Mw / Mn ratio of the high-fluorine-content resin is usually 1 or higher, more preferably 1.1 or higher. The above Mw / Mn ratio is usually 5 or lower, preferably 3 or lower, more preferably 2.5 or lower, and even more preferably 2.2 or lower.

[0128] The content of the high-fluorine resin is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the base resin (total amount if it includes the radiation-sensitive acid-generating resin and resin). The content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. By setting the content of the high-fluorine resin within the above range, the high-fluorine resin can be more effectively distributed to the surface layer of the resist film, and as a result, the elution of the upper part of the pattern during development can be suppressed, and the rectangularity of the pattern can be improved. The radiation-sensitive resin composition may contain one or more high-fluorine resins.

[0129] (Method for synthesizing high-fluorine content resins) High-fluorine-content resins can be synthesized by the same method as the base resin synthesis method described above.

[0130] <Onium salt> Onium salts contain an organic acid anion moiety and an onium cation moiety, and are components that generate acid upon exposure. By including at least a portion of the onium cation moiety in the onium salt, an aromatic ring structure containing a fluorine atom can be achieved, leading to improved sensitivity through increased acid generation efficiency and improved CDU performance through controllable acid diffusion.

[0131] The form in which the onium salt is contained in the radiation-sensitive resin composition is not particularly limited, but it is preferable that the onium salt is at least one selected from the group consisting of a radiation-sensitive acid-generating resin containing a structural unit having the organic acid anion moiety and the onium cation moiety, a radiation-sensitive acid-generating agent containing the organic acid anion moiety and the onium cation moiety, and an acid diffusion control agent containing the organic acid anion moiety and the onium cation moiety, which generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid-generating agent upon irradiation with radiation. The differences in these functions will be described below.

[0132] The acid generated by exposure to an onium salt is thought to perform two functions in the radiation-sensitive resin composition, depending on the strength of the acid. The first function is that the acid generated by exposure dissociates the acid-dissociable groups contained in the resin, generating carboxyl groups, etc. An onium salt having this first function is called a radiation-sensitive acid generator. The second function is that, under pattern-forming conditions using the above-mentioned radiation-sensitive resin composition, it does not substantially dissociate the acid-dissociable groups of the resin, and suppresses the diffusion of the acid generated from the radiation-sensitive acid generator in the unexposed areas by salt exchange. An onium salt having this second function is called an acid diffusion controller. The acid generated from the acid diffusion controller can be said to be a relatively weaker acid (an acid with a high pKa) than the acid generated from the radiation-sensitive acid generator. Whether an onium salt functions as a radiation-sensitive acid generator or an acid diffusion controller depends on the energy required to dissociate the acid-dissociable groups of the resin and the acidity of the onium salt. The radioactive acid generator in a radioactive resin composition may be in the form of an onium salt structure existing as a compound on its own (liberated from the polymer), a form in which the onium salt structure is incorporated as part of the polymer, or both of these forms. The form in which the onium salt structure is incorporated as part of the polymer is specifically called a radioactive acid-generating resin.

[0133] By containing the above-mentioned radiation-sensitive acid generator or radiation-sensitive acid-generating resin in the radiation-sensitive resin composition, the polarity of the resin in the exposed area increases, and the resin in the exposed area becomes soluble in the developer in the case of alkaline aqueous solution development, while it becomes sparingly soluble in the developer in the case of organic solvent development.

[0134] Furthermore, by including the above-mentioned acid diffusion control agent in the radiation-sensitive resin composition, acid diffusion in unexposed areas can be suppressed, enabling the formation of resist patterns with superior pattern developability and CDU performance.

[0135] In the radiation-sensitive resin composition, the onium cation portion of at least one selected from the group consisting of the radiation-sensitive acid-generating resin, the radiation-sensitive acid-generating agent, and the acid diffusion control agent may contain the aromatic ring structure having the fluorine atom.

[0136] Regardless of the form in which the onium salt is contained, it is preferable that the organic acid anion portion has at least one selected from the group consisting of sulfonic acid anions, carboxylic acid anions, and sulfonimide anions. Furthermore, it is preferable that the onium cation is at least one selected from the group consisting of sulfonium cations and iodonium cations. The onium salt can efficiently exhibit the above-mentioned functions by having a combination of these structures.

[0137] Acids generated by exposure include those that produce sulfonic acids, carboxylic acids, and sulfonimides upon exposure, corresponding to the organic acid anions mentioned above.

[0138] For example, as an onium salt that yields sulfonic acid upon exposure, (1) A compound in which one or more fluorine atoms or fluorinated hydrocarbon groups are bonded to a carbon atom adjacent to a sulfonate anion. (2) Compounds in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to a carbon atom adjacent to the sulfonate anion. We can list some examples.

[0139] Examples of onium salts that yield carboxylic acids upon exposure include: (3) A compound in which one or more fluorine atoms or fluorinated hydrocarbon groups are bonded to a carbon atom adjacent to a carboxylate anion. (4) Compounds in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to a carbon atom adjacent to a carboxylate anion. One could list these:

[0140] Of these, the radiation-sensitive acid generator or radiation-sensitive acid-generating resin is preferably one that falls under (1) above. The acid diffusion control agent is preferably one that falls under (2), (3), or (4) above, and is particularly preferably one that falls under (2) or (4).

[0141] <Radiation-sensitive acid generator> Preferably, the radiation-sensitive resin composition further contains a radiation-sensitive acid generator that generates an acid having a lower pKa than the acid generated from the acid diffusion control agent upon irradiation (exposure) with radiation. The inclusion of the radiation-sensitive acid generator in the radiation-sensitive resin composition causes the acid generated by exposure to dissociate the acid-dissociable groups in the resin, generating carboxyl groups and the like. As a result, the polarity of the resin in the exposed area increases, making the resin soluble in the developer in the case of alkaline aqueous solution development, while becoming sparingly soluble in the developer in the case of organic solvent development.

[0142] The radiation-sensitive acid generator preferably comprises an organic acid anion moiety and an onium cation moiety. The organic acid anion moiety preferably has at least one selected from the group consisting of sulfonic acid anions and sulfonimide anions. Examples of acids generated by exposure include sulfonic acid and sulfonimide, corresponding to the above-mentioned organic acid anion moiety. The organic acid anion moiety preferably contains an iodine-substituted aromatic ring structure.

[0143] In particular, as a radiation-sensitive acid generator that yields sulfonic acid upon exposure, a compound in which one or more fluorine atoms or fluorinated hydrocarbon groups are bonded to carbon atoms adjacent to the sulfonate anion can be suitably used.

[0144] The radiation-sensitive acid generator is preferably represented by the following formula (A-1) or formula (A-2).

[0145] [ka]

[0146] In equations (A-1) and (A-2), L 1 This is a C1-C6 alkylene group that is a single bond, an ether bond, or an ester bond, or may contain an ether bond or an ester bond. The alkylene group may be linear, branched, or cyclic.

[0147] R 1 is a hydroxyl group, carboxyl group, fluorine atom, chlorine atom, bromine atom or amino group, or may contain a fluorine atom, chlorine atom, bromine atom, hydroxyl group, amino group or C1-C10 alkoxy group, C1-C20 alkyl group, C1-C20 alkoxy group, C2-C10 alkoxycarbonyl group, C2-C20 acyloxy group or C1-C20 alkylsulfonyloxy group, or -NR 8 -C(=O)-R 9 Alternatively, -NR 8 -C(=O)-OR 9 And R 8 R is a C1-C6 alkyl group which may contain a hydrogen atom, or a halogen atom, a hydroxyl group, a C1-C6 alkoxy group, a C2-C6 acyl group, or a C2-C6 acyloxy group, 9 The group is an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and may contain a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 6 carbon atoms, or an acyloxy group having 2 to 6 carbon atoms. The alkyl group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, and alkenyl group may be linear, branched, or cyclic.

[0148] Of these, R 1 Examples include hydroxyl groups and -NR 8 -C(=O)-R 9 Fluorine atoms, chlorine atoms, bromine atoms, methyl groups, methoxy groups, etc. are preferred.

[0149] R 2When p is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms; when p is 2 or 3, it is a trivalent or tetravalent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0150] Rf 1 ~Rf 4 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one of these is either a fluorine atom or a trifluoromethyl group. Also, Rf 1 and Rf 2 These may combine to form a carbonyl group. In particular, Rf 3 and Rf 4 It is preferable that both are fluorine atoms.

[0151] R 3 , R 4 , R 5 , R 6 and R 7 Each of these is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. 3 , R 4 and R 5 Any two of these groups may bond to each other to form a ring with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched, or cyclic. Specific examples include C1-C12 alkyl groups, C2-C12 alkenyl groups, C2-C12 alkynyl groups, C6-C20 aryl groups, C7-C12 aralkyl groups, etc. Furthermore, some or all of the hydrogen atoms of these groups may be substituted with hydroxyl groups, carboxyl groups, halogen atoms, cyano groups, amide groups, nitro groups, mercapto groups, sultone groups, sulfone groups, or sulfonium salt-containing groups, and some of the carbon atoms of these groups may be substituted with ether bonds, ester bonds, carbonyl groups, carbonate groups, or sulfonic acid ester bonds.

[0152] p is an integer satisfying 1 ≤ p ≤ 3. q and r are integers satisfying 0 ≤ q ≤ 5, 0 ≤ r ≤ 3, and 0 ≤ q + r ≤ 5. q is preferably an integer satisfying 1 ≤ q ≤ 3, and more preferably 2 or 3. r is preferably an integer satisfying 0 ≤ r ≤ 2.

[0153] The organic acid anion portion of the radiation-sensitive acid generator represented by the above formulas (A-1) and (A-2) can be, but are not limited to, those shown below. Furthermore, for the organic acid anion portion that does not have an iodine-substituted aromatic ring structure, a structure in which the iodine atom in the following formula is replaced with a hydrogen atom or other substituent or other atom or group can be suitably adopted.

[0154] [ka]

[0155] [ka]

[0156] Furthermore, below are examples of organic acid anion portions of radiation-sensitive acid generators represented by the above formulas (A-1) and (A-2), as well as examples of organic acid anion portions that do not correspond to formulas (A-1) and (A-2).

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] In the radiation-sensitive acid generator represented by formula (A-1) above, the onium cation portion can suitably adopt the structure shown as the onium cation portion of structural unit B that can be contained in the resin. Among these, an onium cation containing an aromatic ring structure having a fluorine atom is preferred, an onium cation represented by formula (Q-1) above is more preferred, a sulfonium cation having two or more aromatic ring structures having fluorine atoms is even more preferred, and a sulfonium cation having three aromatic ring structures having fluorine atoms is particularly preferred.

[0161] These radiation-sensitive acid generators may be used alone or in combination of two or more. The lower limit of the radiation-sensitive acid generator content is preferably 0.5 parts by mass, more preferably 1 part by mass, even more preferably 1.5 parts by mass, and particularly preferably 2 parts by mass, per 100 parts by mass of the base resin. The upper limit of the above content is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 12 parts by mass or less, per 100 parts by mass of the resin. This allows for excellent sensitivity and CDU performance during resist pattern formation.

[0162] <Acid diffusion control agent> The acid diffusion control agent contains an organic acid anion moiety and an onium cation moiety, and generates an acid with a higher pKa than the acid generated from the above-mentioned radiation-sensitive acid generator upon irradiation with radiation. Examples of such organic acid anion moieties include carboxylic acids. The organic acid anion moiety preferably contains an iodine-substituted aromatic ring structure. The acid diffusion control agent is preferably represented by the following formula (S-1) or the following formula (S-2).

[0163] [ka]

[0164] In equations (S-1) and (S-2), R 1This may be substituted with a hydrogen atom, a hydroxyl group, a fluorine atom, a chlorine atom, an amino group, a nitro group or cyano group, or a halogen atom, and may be an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, or an alkylsulfonyloxy group having 1 to 4 carbon atoms, or -NR 1A -C(=O)-R 1B Alternatively, -NR 1A -C(=O)-OR 1B That is. R 1A R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 1B This is an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms.

[0165] The C1-C6 alkyl group may be linear, branched, or cyclic, and specific examples include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, cyclopentyl, n-hexyl, and cyclohexyl groups. Furthermore, the alkyl portion of the C1-C6 alkoxy group, C2-C7 acyloxy group, and C2-C7 alkoxycarbonyl group can be the same as the specific examples of alkyl groups described above, and the alkyl portion of the C1-C4 alkylsulfonyloxy group can be the C1-C4 alkyl group from the specific examples of alkyl groups described above. The C2-C8 alkenyl group may be linear, branched, or cyclic, and specific examples include vinyl, 1-propenyl, and 2-propenyl groups. Of these, R 1 Examples include fluorine atoms, chlorine atoms, hydroxyl groups, amino groups, C1-C3 alkyl groups, C1-C3 alkoxy groups, C2-C4 acyloxy groups, and -NR. 1A -C(=O)-R 1B , -NR 1A -C(=O)-OR 1B The like are preferable.

[0166] R 3 , R 4 , R 5 , R 6and R 7 Each of these is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. When the onium cation portion of the acid diffusion control agent has a fluorine atom, R 3 , R 4 and R 5 At least one of them contains one or more fluorine atoms, R 6 and R 7 At least one of them contains one or more fluorine atoms. Also, R 3 , R 4 and R 5 Any two of these groups may bond to each other to form a ring with the sulfur atom to which they are bonded. The monovalent hydrocarbon group may be linear, branched, or cyclic. Specific examples include C1-C12 alkyl groups, C2-C12 alkenyl groups, C2-C12 alkynyl groups, C6-C20 aryl groups, C7-C12 aralkyl groups, etc. Furthermore, some or all of the hydrogen atoms of these groups may be substituted with hydroxyl groups, carboxyl groups, halogen atoms, cyano groups, amide groups, nitro groups, mercapto groups, sultone groups, sulfone groups, or sulfonium salt-containing groups, and some of the carbon atoms of these groups may be substituted with ether bonds, ester bonds, carbonyl groups, carbonate groups, or sulfonic acid ester bonds.

[0167] L 1 This is a single bond or a divalent linking group having 1 to 20 carbon atoms, and may include an ether bond, carbonyl group, ester bond, amide bond, sultone ring, lactam ring, carbonate bond, halogen atom, hydroxyl group, or carboxyl group.

[0168] m and n are integers satisfying 0 ≤ m ≤ 5, 0 ≤ n ≤ 3, and 0 ≤ m + n ≤ 5, but integers satisfying 1 ≤ m ≤ 3 and 0 ≤ n ≤ 2 are preferred.

[0169] The following are examples of organic acid anion moieties of the acid diffusion control agent represented by the above formula (S-1) or (S-2), but are not limited to these. While all of the following are organic acid anion moieties having an iodine-substituted aromatic ring structure, for organic acid anion moieties that do not have an iodine-substituted aromatic ring structure, structures in which the iodine atom in the following formula is replaced with a hydrogen atom or other substituent or other atom or group can be suitably adopted.

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] In the acid diffusion control agents represented by the above formulas (S-1) and (S-2), the onium cation portion of structural unit B of the radiation-sensitive acid generating resin can be suitably adopted. Among these, an onium cation containing an aromatic ring structure having a fluorine atom is preferred, an onium cation represented by the above formula (Q-1) is more preferred, a sulfonium cation having two or more aromatic ring structures having fluorine atoms is even more preferred, and a sulfonium cation having three aromatic ring structures having fluorine atoms is particularly preferred.

[0174] The acid diffusion control agents represented by the above formulas (S-1) and (S-2) can also be synthesized by known methods, particularly by salt exchange reactions. Known acid diffusion control agents can also be used as long as they do not impair the effects of the present invention.

[0175] These acid diffusion control agents may be used alone or in combination of two or more. The content ratio of the acid diffusion control agent is preferably 10% by mass or more, more preferably 25% by mass or more, and even more preferably 40% by mass or more with respect to the content of the radiation-sensitive acid generator (in the case of including a radiation-sensitive acid generating resin, the total with the content of structural unit B in 100 parts by mass of the radiation-sensitive acid generating resin). Also, the above ratio is preferably 500% by mass or less, more preferably 200% by mass or less, and even more preferably 100% by mass or less. Thereby, excellent sensitivity and CDU performance can be exhibited during resist pattern formation.

[0176] <Solvent> The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the base resin (at least one of the radiation-sensitive acid generating resin and the resin), and additives contained as desired.

[0177] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

[0178] Examples of the alcohol solvent include monohydric alcohol 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, 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, tripropylene glycol; polyhydric alcohol partial ether solvents in which a part of the hydroxy groups of the above polyhydric alcohol solvents are etherified, and the like.

[0179] Examples of the ether solvent 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 (methylphenyl ether); Examples include polyhydric alcohol ether solvents, which are obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.

[0180] Examples of ketone solvents include chain-like ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclopentanone, cyclohexanone, methylcyclohexanone, and other cyclic ketone solvents: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0181] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples include chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0182] 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-based solvents such as γ-butyrolactone and valerolactone; Carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of polycarboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0183] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbencene, and n-amylnaphthalene.

[0184] Among these, ester solvents and ketone solvents are preferred, polyhydric alcohol partial ether acetate solvents, cyclic ketone solvents, and lactone 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.

[0185] <Other optional ingredients> The above-mentioned radiation-sensitive resin composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, segregation promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, and the like. These other optional components may be used individually or in combination of two or more types.

[0186] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing a base resin (at least one of a radiation-sensitive acid-generating resin and a resin), a solvent, and other optional components as needed, in a predetermined ratio. After mixing, the above radiation-sensitive resin composition is preferably filtered using, for example, a filter with a pore size of about 0.05 μm. The solid content concentration of the above radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0187] <Pattern Formation Method> The pattern formation method in this embodiment is The above radiation-sensitive resin composition is applied directly or indirectly to a substrate to form a resist film (1) (hereinafter also referred to as the "resist film formation step"), The above resist film is exposed (2) (hereinafter also referred to as the "exposure step"), and The process includes (3) developing the exposed resist film (hereinafter also referred to as the "development step").

[0188] According to the pattern formation method described above, a high-quality resist pattern can be formed because the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity and CDU performance in the exposure process, is used. The following describes each step.

[0189] [Resist film formation process] In this step (step (1) above), a resist film is formed using the radiation-sensitive resin composition. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, with 80°C to 120°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred. The thickness of the formed resist film is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0190] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content resin in the above-mentioned radiation-sensitive resin composition, a protective immersion film insoluble in the immersion liquid may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the protective immersion film, either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective immersion film.

[0191] [Synthesis process] In this step (step (2) above), the resist film formed in the resist film formation step (1) above is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion medium such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; or charged particle beams such as electron beams and alpha rays. 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.

[0192] When performing exposure by liquid immersion exposure, examples of the liquid immersion liquid to be used include water, fluorine-based inert liquids, etc. The liquid immersion liquid is preferably a liquid that is transparent to the exposure light wavelength and has a temperature coefficient of refractive index that minimizes the distortion of the optical image projected onto the film as much as possible. However, particularly when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above viewpoints, it is preferable to use water from the viewpoints of easy availability and ease of handling. When using water, an additive that reduces the surface tension of water and increases the interfacial activity may be added in a small proportion. This additive is preferably one that 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.

[0193] After the above exposure, post-exposure baking (PEB) is performed, and in the exposed portion of the resist film, it is preferable to promote the dissociation of the acid-dissociable groups of the resin, etc. by the acid generated from the radiation-sensitive acid generator by exposure. By this PEB, a difference in solubility in the developer occurs between the exposed portion and the unexposed portion. 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.

[0194] [Development process] In this step (the above step (3)), the resist film exposed in the above exposure step, which is the above step (2), is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with a rinse liquid such as water or alcohol and then dry.

[0195] Examples of developers used in the above development process include, in the case of alkaline development, an alkaline aqueous solution containing at least one alkaline compound 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, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0196] In addition, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing organic solvents. Examples of the above organic solvents include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ester solvents and ketone solvents are preferred. As for ester solvents, acetic acid ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of 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 organic solvents in the developer include water and silicone oil.

[0197] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by puddling the developer solution onto the substrate surface using surface tension and leaving it still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method). [Examples]

[0198] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The methods for measuring various physical properties are shown below.

[0199] [Mw and Mn] The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using Tosoh Corporation's GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions. Eluting solvent: Tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0200] [Synthesis Example] Synthesis of base resins (P-1) to (P-18) Each monomer was combined and copolymerized under tetrahydrofuran (THF) solvent, crystallized in methanol, and then washed repeatedly with hexane before isolation and drying to obtain base resins (P-1) to (P-18) with the following compositions. The compositions of the obtained base polymers are: 1 Mw and dispersion (Mw / Mn) were confirmed by 1H-NMR under the GPC conditions described above. The types and amounts of each monomer are shown in Table 1. In the following structural formulas, Me represents a methyl group, Et represents an ethyl group, and iPr represents an isopropyl group.

[0201] [ka]

[0202] [ka]

[0203] [Table 1]

[0204] The structures of the radiation-sensitive acid generators PAG1 to PAG4 and PAGc1 used in the preparation of the radiation-sensitive resin composition are shown below.

[0205] [ka]

[0206] [Examples, Comparative Examples] A radiation-sensitive resin composition was prepared by dissolving each component in a solvent containing 100 ppm of FC-4430, manufactured by 3M, as a surfactant, according to the composition shown in Table 2, and then filtering the mixture through a 0.2 μm nylon filter.

[0207] In Table 2, the components are as follows:

[0208] Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) GBL (γ-butyrolactone) CHN (Cyclohexanone) PGME (Propylene Glycol Monomethyl Ether) DAA (Diacetone Alcohol) EL (Ethyl Lactate)

[0209] Acid diffusion control agents (Q-1)~(Q-3) and (Qc-1)

[0210] [ka]

[0211] High fluorine content resin F-1: Mw=9,000, Mw / Mn=1.9 [ka]

[0212] [Evaluation of sensitivity using EUV exposure] On a 12-inch silicon wafer, an anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form an underlayer anti-reflective coating with an average thickness of 10 nm. On this underlayer anti-reflective coating, each of the radiation-sensitive resin compositions shown in Table 1 was applied using the same spin coater, and PB (plate-forming) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. This resist film was exposed using an EUV scanner (ASML's "NXE3300" (NA0.33, σ0.9 / 0.6, quadruple pole illumination, wafer-side dimension with a pitch of 46 nm, +20% bias hole pattern mask)). A resist pattern with 23 nm holes and a 46 nm pitch was formed by performing PEB on a 120°C hot plate for 60 seconds and developing with a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds. The exposure amount used to form this 23 nm hole, 46 nm pitch resist pattern was defined as the optimal exposure amount (Eop), and this optimal exposure amount was used to determine the sensitivity (mJ / cm²). 2 )

[0213] [CDU Evaluation] The Eop exposure dose determined above was applied, and a resist pattern with 23 nm holes and a 46 nm pitch was formed by the same procedure as described above. The formed resist pattern was observed from the top using a scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000"). The hole diameter was measured at 16 points in the 500 nm range, and the average value was calculated. In addition, the average value was measured at a total of 500 points at arbitrary points. The 3-sigma value was calculated from the distribution of the measured values, and the calculated 3-sigma value was used as the evaluation value (nm) for CDU performance. The smaller the evaluation value for CDU performance, the smaller the variation in hole diameter over long periods, indicating better performance. The results are shown in Table 2. The numbers in parentheses in the sensitivity and CDU columns of Table 2 represent the improvement rate (%) compared to the evaluation results of Comparative Examples 3 and 4.

[0214] [Table 2]

[0215] Evaluation of the resist patterns formed after the above EUV exposure revealed that all of the radiation-sensitive resin compositions in the examples exhibited good sensitivity, CDU, and development residue. [Industrial applicability]

[0216] The radiation-sensitive resin composition and resist pattern formation method described above allow for the formation of resist patterns with good sensitivity to exposure light, excellent CDU performance, and minimal development residue. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. A resin comprising structural unit A having an acid-dissociable group and structural unit D having a phenolic hydroxyl group, Solvent and Includes, The above structural unit D has a phenolic hydroxyl group and an alkyl group on the same aromatic ring, A radiation-sensitive resin composition in which, in the aromatic ring of the above structural unit D, an alkyl group is bonded to the carbon atom adjacent to the carbon atom to which a phenolic hydroxyl group is bonded, However, the above radiation-sensitive resin composition further satisfies at least one selected from the group consisting of the following conditions 1 and 2. Condition 1: The above resin is a radiation-sensitive acid-generating resin containing structural unit B, which further includes an organic acid anion moiety and an onium cation moiety containing an aromatic ring structure having a fluorine atom. Condition 2: Further comprising an onium salt containing an organic acid anion moiety and an onium cation containing an aromatic ring structure having a fluorine atom (excluding the above-mentioned radiation-sensitive acid-generating resin), The above structural unit D is a radiation-sensitive resin composition in which the structural unit is represented by the following formula (D). 【Chemistry 1】 (In the above formula (D), R α These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L ＣＡ is a single bond, or -COO- ＊ * indicates a bonding site on the aromatic ring side. R １０１ This is a hydrogen atom. R １０２ This is a linear or branched alkyl group having 1 to 8 carbon atoms. n ｄ３ is 0, m ｄ３ is 1, m ４ is 1 or 2. However, 2 ≤ m ｄ３ + m ４ ≤ 2n ｄ３ + 5 is satisfied. In formula (D), R is attached to the carbon atom adjacent to the carbon atom to which the phenolic hydroxyl group is bonded. １０２ They are joined together.

2. The radiation-sensitive resin composition according to claim 1, wherein the above-mentioned structural unit A is a structural unit represented by the following formula (1). 【Chemistry 2】 (In the above formula (1), R Ｔ These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R Ｘ It is a monovalent hydrocarbon group having 1 to 20 carbon atoms. Cy represents an alicyclic structure with 3 to 20 members, formed together with the carbon atoms to which it is bonded.

3. The radiation-sensitive resin composition according to claim 1, wherein the onium cation containing the aromatic ring structure having the above-mentioned fluorine atom is represented by the following formula (Q-1). 【Transformation 3】 (In the above formula (Q-1), Ra １ and Ra ２ Each of these independently represents a substituent. n １ n represents an integer from 0 to 5, and n １ If there are two or more, there are multiple Ra １ They may be the same or different. n ２ n represents an integer from 0 to 5, and n ２ If there are two or more, there are multiple Ra ２ They may be the same or different. n ３ n represents an integer from 1 to 5, and n ３ If there are two or more, there are multiple Ra ３ They may be the same or different. Ra ３ This represents a fluorine atom or a group having one or more fluorine atoms. n １ If there are two or more, multiple Ra １ They may be connected to each other to form a ring. n ２ If there are two or more, multiple Ra ２ They may be connected to each other to form a ring. n １ is 1 or more and n ２ If it is 1 or more, Ra １ and Ra ２ They may be connected to each other to form a ring.

4. The radiation-sensitive resin composition according to claim 1, wherein the resin comprises an iodine-substituted aromatic ring structure.

5. A radiation-sensitive resin composition that satisfies the above condition 1, In the above condition 1, further, A radiation-sensitive acid generator containing an organic acid anion portion and an onium cation portion (excluding the above-mentioned radiation-sensitive acid-generating resin), and An acid diffusion control agent comprising an organic acid anion portion and an onium cation portion, which generates an acid having a higher pKa than the acid generated from the above-mentioned radiation-sensitive acid generator upon irradiation with radiation (excluding the above-mentioned radiation-sensitive acid-generating resin). The radiation-sensitive resin composition according to claim 1, comprising at least one selected from the group consisting of the following.

6. The radiation-sensitive resin composition according to claim 1, wherein the above structural unit B is a structural unit derived from a monomer represented by the following formula (2) or a monomer represented by formula (3). 【Chemistry 4】 (In equations (2) and (3) above, R Ａ and R Ｂ These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R Ｙ and R Ｚ Each is independently a hydrogen atom, a fluorine atom, or a fluorinated hydrocarbon group, and at least one is a fluorine atom or a fluorinated hydrocarbon group. Ｙ and R Ｚ They may be the same or different. s is an integer between 1 and 20. R １ ~R ３ This is independently a monovalent hydrocarbon group and an aromatic ring having at least one fluorine atom. R ４ ~R ６ This is independently a monovalent hydrocarbon group and an aromatic ring having at least one fluorine atom. Y １ This is a single bond, or -Y １１ -C (=O)-O-. Y １１ This refers to a divalent hydrocarbon group having 1 to 20 carbon atoms or a divalent hydrocarbon group having 1 to 20 carbon atoms containing a heteroatom. Y ２ This consists of a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, and -O-Y. ２１ -, -C(=O)-O-Y ２１ - or -C (=O)-NH-Y ２１ - is Y ２１ This group is an alkanediyl group having 1 to 6 carbon atoms, an alkenediyl group having 2 to 6 carbon atoms, or a phenylene group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. The alkanediyl group having 1 to 6 carbon atoms, the alkenediyl group having 2 to 6 carbon atoms, and the phenylene group may be substituted with a fluorine atom.

7. A radiation-sensitive resin composition that satisfies the above condition 2, The onium salt in condition 2 above is A radiation-sensitive acid generator containing an organic acid anion moiety and an onium cation moiety, and An acid diffusion control agent comprising an organic acid anion moiety and an onium cation moiety, which generates an acid having a higher pKa than the acid generated from the above-mentioned radiation-sensitive acid generator upon irradiation with radiation. It includes at least one selected from the group consisting of, The radiation-sensitive resin composition according to claim 1, wherein at least one of the onium cation portion constituting the radiation-sensitive acid generator and the onium cation portion constituting the acid diffusion control agent is an onium cation containing an aromatic ring structure having a fluorine atom.

8. The radiation-sensitive resin composition according to claim 5, wherein at least one organic acid anion moiety selected from the group consisting of the above-mentioned radiation-sensitive acid generator and the above-mentioned acid diffusion control agent comprises an iodine-substituted aromatic ring structure.

9. The radiation-sensitive resin composition according to claim 7, wherein at least one organic acid anion moiety selected from the group consisting of the above-mentioned radiation-sensitive acid generator and the above-mentioned acid diffusion control agent comprises an iodine-substituted aromatic ring structure.

10. A step of forming a resist film by directly or indirectly applying the radiation-sensitive resin composition according to any one of claims 1 to 9 to a substrate, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. A pattern formation method including the following.

11. The pattern forming method according to claim 10, wherein the exposure is performed using extreme ultraviolet light or an electron beam.

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