Radiation-sensitive resin composition, pattern forming method, radiation-sensitive acid generator, and acid diffusion control agent

Abstract

The present invention provides a radiation sensitive resin composition, a pattern forming method, etc., capable of achieving, at sufficient levels, sensitivity, LWR performance, and process window when next-generation technology is applied.　This radiation sensitive resin composition comprises a resin that includes a repeating unit A having an acid dissociable group, an onium salt that has an organic acid anion moiety and an onium cation moiety, and a solvent, wherein the onium salt includes at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group.

Description

[Technical Field]

[0001] The present invention relates to a radiation-sensitive resin composition, a pattern-forming method, a radiation-sensitive acid generator, and an acid diffusion control agent. [Background technology]

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, generating acid by irradiating a resist composition film with radiation through a mask pattern. This acid then acts as a catalyst, creating a difference in the solubility of the resin in alkaline or organic solvent-based developers 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 Initiative] [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, LWR performance (an indicator of line width uniformity), and process window width.

[0006] The present invention aims to provide a radiation-sensitive resin composition, a pattern-forming method, a radiation-sensitive acid generator, and an acid diffusion control agent that can exhibit sufficient levels of sensitivity, LWR performance, and process window 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 containing repeating unit A having an acid-dissociable group, An onium salt containing an organic acid anion moiety and an onium cation moiety, Solvent and Includes, The above-mentioned onium salt relates to a radiation-sensitive resin composition comprising at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group.

[0009] The radiation-sensitive resin composition in question allows for the construction of a resist film that satisfies the requirements for sensitivity, LWR performance, and process window. 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 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, LWR performance, and process window, thus enabling the efficient formation of high-quality resist patterns.

[0012] Furthermore, in another embodiment, the present invention, It contains an onium salt comprising an organic acid anion moiety and an onium cation moiety, The above onium salt relates to a compound containing at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group.

[0013] Furthermore, in another embodiment, the present invention states that It contains an onium salt comprising an organic acid anion moiety and an onium cation moiety, The above-mentioned onium salt relates to a radiation-sensitive acid generator comprising a compound containing at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group.

[0014] Furthermore, in another embodiment, the present invention states that It contains an onium salt comprising an organic acid anion moiety and an onium cation moiety, The above onium salt relates to an acid diffusion control agent comprising a compound containing at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group. [Modes for carrying out the invention]

[0015] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0016] <Radiation sensitive resin composition>

[0017] The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "the composition") comprises a radiation-sensitive 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 in the radiation-sensitive resin composition, a high level of sensitivity, LWR performance, and process window can be imparted to the resulting resist film.

[0018] <Resin> The resin is an aggregate (G1) of polymers containing repeating units A having acid-dissociable groups (hereinafter, polymer (G1) is also referred to as the "base resin"). In addition to repeating units A, the base resin may also contain repeating units B containing organic acid anion moieties and onium cation moieties, structural units D having phenolic hydroxyl groups, structural units E containing lactone structures, and other structural units. Each structural unit will be described below.

[0019] (Repeating unit A) The repeating unit A (hereinafter also referred to as "structural unit A") is preferably a repeating unit represented by the following formula (1).

[0020] [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.

[0021] 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.

[0022] 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 1 to 10 carbon atoms.

[0023] 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 carbon atoms constituting the alicyclic ring that are not adjacent to each other are bonded together by a bond chain containing one or more carbon atoms.

[0024] 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.

[0025] R X Preferred carbon groups 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.

[0026] The alicyclic structure with 3 to 20 ring members in Cy is not particularly limited as long as it has an alicyclic structure, and may have monocyclic, bicyclic, tricyclic, tetracyclic, or polycyclic structures with more members, and may be a bridged ring structure, a spirocyclic structure, a ring aggregate structure in which multiple rings are directly linked by single or double bonds, or a combination thereof. In particular, it is preferable to have a bridged ring structure of a monocyclic, bicyclic, tricyclic, or tetracyclic form, and more preferably it is a ring structure of cyclopentane, cyclohexane, norbornane, adamantane, tricyclo[5.2.1.02,6]decane, tetracyclo[4.4.0.12,5.17,10]dodecane, perhydronaphthalene, or perhydroanthracene, or a derivative thereof.

[0027] The repeating unit represented by formula (1) above is preferably represented by, for example, the following formulas (A-1) to (A-8).

[0028] [ka]

[0029] In the above formulas (A-1) to (A-8), RT and RX are equivalent to those in formula (1). In particular, structural unit A is preferably represented by the above formulas (A-1), (A-4), (A-5), (A-6), and (A-8).

[0030] It is also preferable that structural unit A is a repeating unit represented by the following formula (1-2).

[0031] [ka] (In the above equation (1-2), R c Lc is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R is a single bond or a divalent linking group. c1 , R c2 and R c3 These are, independently, monovalent hydrocarbon groups having 1 to 20 carbon atoms.

[0032] R c As for, from the viewpoint of copolymerizability of the monomer that gives the structural unit represented by formula (1-2), a hydrogen atom or a methyl group is preferable.

[0033] L c Examples of the divalent linking group represented by include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, -OR LA -*, -COOR LB -* and the like (* represents the bond on the carbonyl group side).

[0034] As the above alkanediyl group, an alkanediyl group having 1 to 8 carbon atoms is preferable.

[0035] Examples of the above cycloalkanediyl group include monocyclic cycloalkanediyl groups such as a cyclopentanediyl group and a cyclohexanediyl group; and polycyclic cycloalkanediyl groups such as a norbornanediyl group and an adamantanediyl group. As the above cycloalkanediyl group, a cycloalkanediyl group having 5 to 12 carbon atoms is preferable.

[0036] Examples of the above alkenediyl group include an ethenediyl group, a propenediyl group, a butenediyl group and the like. As the above alkenediyl group, an alkenediyl group having 2 to 6 carbon atoms is preferable.

[0037] The above -OR LA -*'s R LA includes the above alkanediyl group, the above cycloalkanediyl group, the above alkenediyl group and the like. The above -COOR LB -*'s R LB includes the above alkanediyl group, the above cycloalkanediyl group, the above alkenediyl group, an arenediyl group and the like. Examples of the arenediyl group include a benzenediyl group, a tolylene group, a naphthalenediyl group and the like. As the above arenediyl group, an arenediyl group having 6 to 15 carbon atoms is preferable.

[0038] Among these, L cis a single bond or -COOR LB -* is preferable. LB An alkanediyl group is preferred as the group.

[0039] 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 halides such as trifluoromethyl groups, alkoxy groups such as methoxy groups, cyano groups, etc.

[0040] R c1 , R c2 and R c3 As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1), the group shown as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by RX can be adopted.

[0041] 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 the group is a monovalent alicyclic or aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0042] The repeating unit represented by formula (1-2) is preferably represented by the following formulas (2-1) to (2-18).

[0043] [ka]

[0044] [ka]

[0045] In equations (2-1) to (2-18) above, Rc is equivalent to that in equation (2) above. In particular, it is preferable that it be expressed in equations (2-1) to (2 to 3) and (2-10) to (2 to 12) above.

[0046] 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 LWR performance.

[0047] (Repeating unit B) Repeating unit B (hereinafter also referred to as "structural unit B") is a repeating unit that includes an organic acid anion moiety and an onium cation moiety. Resins containing structural unit B are hereinafter also referred to as "radiation-sensitive acid-generating resins".

[0048] The above structural unit B is a repeating unit 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 the onium cation portion in structural unit B include sulfonium cations and iodonium cations.

[0049] In the above structural unit B, the onium cation portion is preferably a sulfonium cation, and the monomer that gives such structural unit B is preferably a repeating unit derived from, for example, the monomer represented by formula (2) or the monomer represented by formula (3) below.

[0050] [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. n 11 This is an integer between 1 and 20. R 1T ~R 3T It is independently a monovalent hydrocarbon group. R 4T ~R 6T It is independently a monovalent hydrocarbon group. Y 1 This is a single bond, or -Y 11 -C(=O)-O- Y 11 This is a divalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. 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 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.

[0051] In equations (2) and (3), R Y and R ZEach 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. The multiple RY and RZ groups may be the same or different.

[0052] In formula (2), Y 1 ga-Y 11 If -C(=O)-O-, then Y 11 Examples of divalent hydrocarbon groups having 1 to 20 carbon atoms that may contain a heteroatom represented by the formula shown below include, but are not limited to, those listed below. Furthermore, the hydrogen atoms in the structures shown below may be substituted with substituents containing heteroatoms. Such substituents include halogen atoms (fluorine, chlorine, bromine, iodine), carboxyl groups, hydroxyl groups, thiol groups, and amino groups.

[0053] [ka] (In the equation, dashed lines represent connections.)

[0054] 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.

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] In equations (2) and (3), R 1T ~R 3T R is independently a monovalent hydrocarbon group, 4T ~R 6T R is independently a monovalent hydrocarbon group. 1T ~R 3T In the monovalent hydrocarbon group, at least one is preferably an aromatic ring having a fluorine atom, R 4T ~R 6TIn the above, it is preferable that at least one of the monovalent hydrocarbon groups is an aromatic ring having a fluorine atom. In this specification, "aromatic ring having a fluorine atom" refers to a structure in which some or all of the hydrogen atoms contained in the aromatic ring are substituted with a fluorine atom, a fluorinated hydrocarbon group (preferably a perfluoro hydrocarbon group), a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group. The above monovalent hydrocarbon group may be linear, branched, or cyclic, and specific examples include those similar to the hydrocarbon groups that constitute the fluorinated hydrocarbon group in RY and RZ, and are preferably aryl groups. Furthermore, some of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms. 1T ~R 3T Any two or more of these may bond with each other to form a ring with the sulfur atom to which they are bonded, 4T ~R 6T Two or more of these may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0061] The onium cation portion in formulas (2) and (3) is preferably represented by the following formula (Q-1).

[0062] [ka]

[0063] 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 Ra1 atoms may be the same or different. n2 represents an integer from 0 to 5, and if n2 is 2 or greater, multiple Ra2 atoms may be the same or different. n3 represents an integer from 1 to 5, and if n3 is 2 or greater, multiple Ra3 atoms may be the same or different. Ra3 represents a substituent. Ra1 and Ra2 may be linked to each other to form a ring. If n1 is 2 or greater, multiple Ra1 atoms may be linked to each other to form a ring. If n2 is 2 or greater, multiple Ra2 atoms 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).

[0064] Preferred substituents represented by Ra1 and Ra2 are alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkyloxy groups, alkoxycarbonyl groups, alkylsulfonyl groups, hydroxyl groups, halogen atoms, halogenated hydrocarbon groups, pentafluorosulfanyl groups, pentafluorosulfanyloxy groups, and pentafluorosulfanylthio groups.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] Examples of the alkoxy carbonyl 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.

[0070] 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.

[0071] 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.

[0072] Examples of halogen atoms for Ra1 and Ra2 include fluorine, chlorine, bromine, and iodine atoms, with fluorine being preferred.

[0073] 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.

[0074] 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.

[0075] Preferred substituents represented by Ra3 include alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkyloxy groups, alkoxycarbonyl groups, alkylsulfonyl groups, hydroxyl groups, halogen atoms, halogenated hydrocarbon groups, pentafluorosulfanyl groups, pentafluorosulfanyloxy groups, and pentafluorosulfanylthio groups. Among these, at least one Ra3 is preferably a fluorine atom or a group having one or more fluorine atoms, and at least one Ra3 is more preferably a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group. Examples of groups having fluorine atoms include groups in which alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkyloxy groups, alkoxycarbonyl groups, and alkylsulfonyl groups are substituted with fluorine atoms as Ra1 and Ra2. Among these, fluorinated alkyl groups are particularly preferred, such as CF3, C2F5, C3F7, C4F9, and C5F 11 , C6F 13 , C7F15 , C8F 17 CH2CF3, CH2CH2CF3, CH2C2F5, CH2CH2C2F5, CH2C3F7, CH2CH2C3F7, CH2C4F9 and CH2CH2C4F9 can be further preferred, and CF3 can be particularly preferred.

[0076] Ra3 is preferably a fluorine atom, CF3, a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group.

[0077] n1 and n2 are preferably integers between 0 and 3, and preferably integers between 0 and 2, respectively.

[0078] n3 is preferably an integer between 1 and 3, and more preferably 1 or 2.

[0079] (n1+n2+n3) is preferably an integer between 1 and 15, more preferably an integer between 1 and 9, even more preferably an integer between 2 and 6, and particularly preferably an integer between 3 and 6.

[0080] 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.

[0081] Diaryliodonium cations are also preferred as the onium cation portion in structural unit B.

[0082] Specific examples of diaryliodonium cations are listed below. While all of the examples below contain an iodonium cation moiety with an aromatic ring structure containing a fluorine atom, structures in which the fluorine atom is replaced with a fluorinated hydrocarbon group such as a trifluoromethyl group, or structures in which the fluorine atom is replaced with a hydrogen atom, can also be suitably employed.

[0083] [ka]

[0084] The content of structural unit B in the resin (total if multiple types of structural unit C 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 the above range, the acid generator can fully exhibit its function.

[0085] (Repeating unit D) The repeating unit D (hereinafter also referred to as "structural unit D") is a structural unit having a phenolic hydroxyl group. In the present invention, phenolic hydroxyl groups generated by deprotection due to the action of acids generated by exposure are also included as phenolic hydroxyl groups of structural unit D. By including structural unit D in the resin, the solubility in the developer can be adjusted more appropriately, and as a result, the sensitivity of the above-mentioned radiation-sensitive resin composition can be further improved. Furthermore, when KrF excimer laser light, EUV, electron beams, etc. are used as the radiation irradiated in the exposure step in the resist pattern formation method, structural unit D contributes to improving etching resistance and improving the difference in developer solubility between the exposed and unexposed areas (dissolution contrast). In particular, it can be suitably applied to pattern formation using exposure with radiation of wavelength 50 nm or less, such as electron beams and EUV. The structural unit D is preferably a repeating unit represented by the following formula (D).

[0086] [ka] (In the above formula (D), R α These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L CA The bonds are single bonds, -COO-*, or -O-. * indicates a bond on the aromatic ring side. R 101 R is a protecting group that is deprotected by the action of a hydrogen atom or an acid. 101If multiple R 101 They are either identical or different from one another. R 102 These are cyano groups, nitro groups, alkyl groups, fluorinated alkyl groups, alkoxycarbonyloxy groups, acyl groups, or acyloxy groups. n d3 is an integer between 0 and 2, m d3 m is an integer from 1 to 8. d4 m is an integer between 1 and 8, where 1 ≤ m d3 +m d4 ≤ 2n d3 (Saves +5.)

[0087] The above R α From the viewpoint of copolymerization of the monomer that gives structural unit D, it is preferable that it be a hydrogen atom or a methyl group.

[0088] As the LCA, a single bond or -COO-* is preferred.

[0089] 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.

[0090] [ka]

[0091] 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 is preferably an alkyl group having 1 to 40 carbon atoms, and more preferably an alkyl group having 1 to 20 carbon atoms. In formula (AL-1), a is an integer from 0 to 10, and preferably an integer from 1 to 5. In formulas (AL-1) to (AL-3), * represents a bond with another part.

[0092] In the above formula (AL-2), RM3 and R M4 each independently represent a hydrogen atom or a monovalent hydrocarbon group, and may contain a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom or fluorine atom. The monovalent hydrocarbon group may be linear, branched or cyclic, and is preferably an alkyl group having 1 to 20 carbon atoms. Further, R M2 , R M3 and R M4 any two of which may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded or the carbon atom and oxygen atom to which they are bonded. The ring is preferably a ring having 4 to 16 carbon atoms, and particularly preferably an alicyclic ring.

[0093] In the above formula (AL-3), R M5 , R M6 and R M7 each independently represent a monovalent hydrocarbon group, and may contain a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom or fluorine atom. The monovalent hydrocarbon group may be linear, branched or cyclic, and is preferably an alkyl group having 1 to 20 carbon atoms. Further, R M5 , R M6 and R M7 any two of which may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded. The ring is preferably a ring having 5 to 16 carbon atoms, and particularly preferably an alicyclic ring.

[0094] Among these, as the protecting group that is deprotected by the action of an acid, a group represented by the above formula (AL-3) is preferable.

[0095] R 102Examples of the alkyl group in the above include linear or branched alkyl groups having 1 to 8 carbon atoms such as methyl group, ethyl group and propyl group. Examples of the fluorinated alkyl group include linear or branched fluorinated alkyl groups having 1 to 8 carbon atoms such as trifluoromethyl group and pentafluoroethyl group. Examples of the alkoxycarbonyloxy group include chain or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms such as methoxycarbonyloxy group, butoxycarbonyloxy group and adamantylmethyloxycarbonyloxy group. Examples of the acyl group include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms such as acetyl group, propionyl group, benzoyl group and acryloyl group. Examples of the acyloxy group include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms such as acetyloxy group, propionyloxy group, benzoyloxy group and acryloyloxy group.

[0096] The above n d3 is more preferably 0 or 1, and still more preferably 0.

[0097] The above m d3 is preferably an integer of 1 to 3, more preferably 1 or 2.

[0098] The above m d4 is preferably an integer of 0 to 3, more preferably an integer of 0 to 2.

[0099] The structural unit D is preferably, for example, structural units represented by the following formulas (D-1) to (D-10) (hereinafter also referred to as "structural unit (D-1) to structural unit (D-10)").

[0100]

Chemical Formula

[0101] In the above formulas (D-1) to (D-10), Rα is the same as defined in the above formula (D).

[0102] Among these, the above structural units (D-1) to (D-5) and (D-7) to (D-10) are preferred.

[0103] 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, and even more preferably 40 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, LWR performance, and process window.

[0104] (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.

[0105] 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.

[0106] 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 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.

[0107] 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 is preferably contained in structural units A, B, D, E, or other structural units other than A to E, and more preferably contained in structural units B, D, or other structural units other than A to E. 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 radiation-sensitive resin composition can further improve lithography performance such as LWR performance.

[0108] (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.

[0109] 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.

[0110] 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.

[0111] 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

[0112] 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.

[0113] <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 and the distribution of components within the resist film can be controlled to a desired state.

[0114] 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").

[0115] [ka]

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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 selected from the group consisting of iodine atoms and bromine atoms.

[0124] 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 400 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] (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.

[0129] <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 one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group in the onium salt, it is possible to achieve high sensitivity through improved acid generation efficiency and LWR performance through controllable acid diffusion.

[0130] 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 resin containing structural unit B having the organic acid anion moiety and the onium cation moiety, a radiation-sensitive acid generator 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 that generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon irradiation with radiation. The differences in these functions will be described below.

[0131] 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, if the resin contains structural units with acid-dissociable groups, the acid generated by exposure dissociates the acid-dissociable groups of those structural units, 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, the acid-dissociable groups of the resin are not substantially dissociated, and the diffusion of the acid generated from the radiation-sensitive acid generator in the unexposed areas is suppressed by salt exchange. An onium salt having this second function is called an acid diffusion controller. The acid generated from the acid diffusion controller is relatively weaker (higher 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.

[0132] 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.

[0133] 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 a resist pattern with superior pattern developability and LWR performance.

[0134] In the radiation-sensitive resin composition, it is preferable that 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 contains the aromatic ring structure having the fluorine atom.

[0135] 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 portion has at least one selected from the group consisting of sulfonium cations and iodonium cations. By having a combination of these structures in the onium salt, the above-mentioned functions can be efficiently exhibited.

[0136] Acids generated by exposure include those that produce sulfonic acids, carboxylic acids, and sulfonimides upon exposure, corresponding to the organic acid anions mentioned above.

[0137] 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.

[0138] 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. We can list some examples.

[0139] 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).

[0140] <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.

[0141] The radiation-sensitive acid generator 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 organic acid anion moiety. The organic acid anion moiety preferably contains an iodine-substituted aromatic ring structure.

[0142] 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.

[0143] The radiation-sensitive acid generator is preferably represented by the following formula (A-1) or formula (A-2).

[0144] [ka]

[0145] In equations (A-1) and (A-2), L1 This is an alkylene group having 1 to 6 carbon atoms, which may be a single bond, an ether bond, or an ester bond, or which may contain an ether bond or an ester bond. The alkylene group may be linear, branched, or cyclic.

[0146] R 1 This is a hydroxyl group, carboxyl group, fluorine atom, chlorine atom, bromine atom, pentafluorosulfanyl group, pentafluorosulfanyloxy group, pentafluorosulfanylthio group 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 That is. 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 This 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 also 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.

[0147] Of these, R 1 Examples include hydroxyl groups and -NR 8 -C(=O)-R 9 Fluorine atoms, chlorine atoms, bromine atoms, pentafluorosulfanyl groups, pentafluorosulfanyloxy groups, pentafluorosulfanylthio groups, methyl groups, methoxy groups, etc. are preferred.

[0148] R 2 When 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.

[0149] 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.

[0150] 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, pentafluorosulfanyl groups, pentafluorosulfanyloxy groups, pentafluorosulfanylthio groups, cyano groups, amide groups, nitro groups, mercapto groups, sultone groups, sulfonate groups, or sulfonium salt-containing groups. Some of the carbon atoms of these groups may also be substituted with ether bonds, ester bonds, carbonyl groups, carbonate groups, or sulfonic acid ester bonds.

[0151] 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. If r is an integer satisfying 1 ≤ r ≤ 3, then at least one R 1 It is preferably a fluorine atom, a fluorinated hydrocarbon group, a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group, and at least one R 1 It is more preferable that the group is a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group.

[0152] 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.

[0153] [ka]

[0154] [ka]

[0155] [ka]

[0156] [ka]

[0157] [ka]

[0158] 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, and an onium cation containing an aromatic ring structure having a fluorine atom, a CF3 group, a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group is more preferred. Specifically, an onium cation represented by formula (Q-1) above can be given, in which case at least one Ra3 in formula (Q-1) is a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group.

[0159] 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 LWR performance during resist pattern formation.

[0160] A radiation-sensitive acid generator containing at least one group selected from the group consisting of a pentafluorosulfanil group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group may be used in combination with a radiation-sensitive acid generator that does not contain any of the pentafluorosulfanil group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group (hereinafter also referred to as "other radiation-sensitive acid generators"). When other radiation-sensitive acid generators are included, the upper limit of the content of the other radiation-sensitive acid generators is preferably 45% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less, relative to the total content of the radiation-sensitive acid generators. The lower limit of the content of the other radiation-sensitive acid generators is 1% by mass or more, relative to the total content of the radiation-sensitive acid generators.

[0161] <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).

[0162] [ka]

[0163] In equations (S-1) and (S-2), R 1 This may be substituted with a hydrogen atom, a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, a pentafluorosulfanylthio group, an amino group, a nitro group or cyano group, or a halogen atom, and may be a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C6 acyloxy group or a C1-C4 alkylsulfonyloxy group, or -NR 1A -C(=O)-R 1B Alternatively, -NR 1A -C(=O)-OR1B 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.

[0164] The above C1-C6 alkyl groups may be linear, branched, or cyclic. 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 C1-C6 alkoxy groups, C2-C7 acyloxy groups, and C2-C7 alkoxycarbonyl groups can be the same as the specific examples of alkyl groups mentioned above. The alkyl portion of the C1-C4 alkylsulfonyloxy groups can be the C1-C4 alkyl groups mentioned above. The above C2-C8 alkenyl groups may be linear, branched, or cyclic. Specific examples include vinyl, 1-propenyl, and 2-propenyl groups. Of these, R 1 Examples include fluorine atoms, chlorine atoms, chlorine atoms, pentafluorosulfanyl groups, hydroxyl groups, amino groups, C1-C3 alkyl groups, C1-C3 alkoxy groups, C2-C4 acyloxy groups, and -NR groups. 1A -C(=O)-R 1B , -NR 1A -C(=O)-OR 1B The like are preferable.

[0165] 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. 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 R7 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.

[0166] L 1 This is a single bond or a divalent linking group having 1 to 20 carbon atoms, and may include an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, or a carboxyl group.

[0167] 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. If n is an integer satisfying 1 ≤ r ≤ 3, then at least one R 1 It is preferably a fluorine atom, a fluorinated hydrocarbon group, a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group, and at least one R 1 It is more preferable that the group is a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group.

[0168] 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.

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] 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, and an onium cation containing an aromatic ring structure having a fluorine atom, a CF3 group, a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group is more preferred. Specifically, an onium cation represented by the above formula (Q-1) can be given, in which case at least one Ra3 in formula (Q-1) is a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, or a pentafluorosulfanylthio group.

[0173] 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.

[0174] These acid diffusion control agents may be used individually or in combination of two or more. The content of the acid diffusion control agent is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, relative to the content of the radiation-sensitive acid generator (or, if a radiation-sensitive acid-generating resin is included, the total content including the content of structural unit B in 100 parts by mass of the radiation-sensitive acid-generating resin). Furthermore, the above percentage is preferably 100% by mass or less, more preferably 80% by mass or less, and even more preferably 60% by mass or less. This allows for excellent sensitivity and LWR performance during resist pattern formation.

[0175] <Solvent> The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least the base resin (at least one of the radiation-sensitive acid-generating resin and the resin), and optionally any additives.

[0176] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0177] Examples of alcohol-based solvents include, Monoalcohol solvents with 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; Polyhydric alcohol solvents with 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples include polyhydric alcohol partial ether solvents, in which some of the hydroxyl groups of the above-mentioned polyhydric alcohol solvents have been etherified.

[0178] Examples of ether-based solvents include: Dialkyl ether-based solvents such as diethyl ether, dipropyl ether, and dibutyl ether; Cyclic ether-based solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether-based solvents such as diphenyl ether and anisole (methyl phenyl ether); And polyhydric alcohol ether-based solvents obtained by etherifying the hydroxy groups of the aforementioned polyhydric alcohol-based solvents, and the like.

[0179] Examples of ketone-based solvents include chain ketone-based solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclic ketone-based solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone: 2,4-pentanedione, acetonylacetone, acetophenone, and the like.

[0180] Examples of amide-based solvents include cyclic amide-based solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Chain amide-based solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide, and the like.

[0181] Examples of ester-based solvents include: Monocarboxylic acid ester-based solvents such as n-butyl acetate and ethyl lactate; Polyhydric alcohol partial ether acetate-based 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.

[0182] Examples of hydrocarbon solvents include, for example, 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.

[0183] 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.

[0184] <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.

[0185] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing a base resin, an onium salt, and a solvent with other optional components as needed in predetermined proportions. 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.

[0186] <Compound> The compound according to this embodiment comprises an onium salt containing an organic acid anion moiety and an onium cation moiety, wherein the onium salt contains at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group. In this embodiment, the organic acid anion moiety may contain at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group. In this case, it is preferable that the organic acid anion has at least one selected from the group consisting of a sulfonic acid anion, a carboxylic acid anion, and a sulfonimide anion. In this embodiment, the onium cation moiety may also contain at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group. Alternatively, both the organic acid anion moiety and the onium cation moiety may contain at least one group selected from the group consisting of a pentafluorosulfanyl group, a pentafluorosulfanyloxy group, and a pentafluorosulfanylthio group. Because the compound according to this embodiment has a high level of sensitivity, when used as a radiation-sensitive acid generator or acid diffusion control agent in a radiation-sensitive resin composition, it can provide a high level of LWR performance and a process window.

[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 a step (3) of 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 radiation-sensitive resin composition, which has excellent sensitivity and LWR 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 exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorine-based inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0193] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in the resin, etc., by the acid generated from the radiation-sensitive acid generator during exposure in the exposed portion of the resist film. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, with 80°C to 130°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0194] [Development process] In this step (the aforementioned step (3)), the resist film exposed in the exposure step that is the aforementioned step (2) is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to perform washing with a rinse liquid such as water or an alcohol, followed by drying.

[0195] As the developer used for the aforementioned development, in the case of alkaline development, examples thereof include alkaline aqueous solutions in which 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 is dissolved. Among these, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.

[0196] Moreover, in the case of organic solvent development, examples thereof include organic solvents such as hydrocarbon-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, and alcohol-based solvents, or solvents containing an organic solvent. As the aforementioned organic solvent, for example, one or two or more of the solvents enumerated above as the solvent for the radiation-sensitive resin composition can be cited. Among these, ester-based solvents and ketone-based solvents are preferable. As the ester-based solvent, acetate ester-based solvents are preferable, and n-butyl acetate and amyl acetate are more preferable. As the ketone-based solvent, chain ketones are preferable, and 2-heptanone is more preferable. The content of the organic solvent in the developer is preferably 80 mass% or more, more preferably 90 mass% or more, further preferably 95 mass% or more, and particularly preferably 99 mass% or more. As components other than the organic solvent in the developer, for example, water, silicone oil, and the like can be cited.

[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. Eluent: 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] <[A] Synthesis of polymers> The monomers used in the synthesis of each polymer (hereinafter also referred to as "compound (M-1) to compound (M-11)") are shown below.

[0201] [ka]

[0202] [Polymer Synthesis Example 1] Synthesis of Polymer (A-1) Compounds (M-1) and (M-3) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomers) in a molar ratio of 40 / 60. Next, azobisisobutyronitrile was added as an initiator at a concentration of 6 mol% relative to the total amount of monomers to prepare a monomer solution. Meanwhile, 100 parts by mass of 1-methoxy-2-propanol (100 parts by mass relative to the total amount of monomers) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for a further 3 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature. The cooled polymerization solution was added to hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, filtered, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours while stirring.

[0203] After the reaction was complete, the residual solvent was removed by distillation, and the resulting solid was dissolved in acetone (100 parts by mass). The solid was added dropwise to 500 parts by mass of water to solidify the resin, and the resulting solid was filtered off. It was dried at 50°C for 12 hours to synthesize a white powdery polymer (A-1).

[0204] [Polymer synthesis examples 2-9] Polymers (A-2) to (A-9) were synthesized in the same manner as in Synthesis Example 1, except that the monomer species and ratios were changed.

[0205] [Polymer Synthesis Example 10] Polymer (A-10) was synthesized by performing a polymerization reaction using compounds (M-10), (M-3), and (M-13) according to a known method.

[0206] [Table 1]

[0207] [B] Synthesis of radiation-sensitive acid generators [Synthesis Example of Radiation-Sensitive Acid Generator 1] Synthesis of Radiation-Sensitive Acid Generator (B-1) 44 mmol of diphenyl sulfoxide and 480 g of tetrahydrofuran were added to the reaction vessel. After stirring under ice cooling, 134 mmol of chlorotrimethylsilane (TMS-Cl) was added dropwise. Subsequently, a 1 M solution of tetrahydrofuran containing 134 mmol of the compound represented by the following formula (S-1) was added dropwise. After stirring at room temperature for 1 hour, a 2 M aqueous hydrochloric acid solution was added. The aqueous layer was separated and washed with diethyl ether. The organic layer was then extracted by liquid-liquid separation with dichloromethane. After drying with sodium sulfate, the solvent was removed by distillation. By purification by column chromatography, the compound represented by the following formula (S-2) (hereinafter also referred to as "bromide salt (S-2)") was obtained.

[0208] Next, 26.0 mmol of the bromide salt (S-2), 26.0 mmol of the compound represented by the following formula (P-1) (hereinafter also referred to as "ammonium salt (P-1)"), 150 g of dichloromethane, and 150 g of ultrapure water were added to the reaction vessel. After stirring at room temperature for 30 minutes, the organic layer was separated. The obtained organic layer was washed with ultrapure water. After drying over anhydrous sodium sulfate, the solvent was removed by distillation. By purification by column chromatography, the compound represented by the following formula (B-1) (hereinafter also referred to as "radiation-sensitive acid generator (B-1)") was obtained. The synthesis scheme of the radiation-sensitive acid generator (B-1) is shown below.

[0209] [ka]

[0210] [Examples of synthesis of radiation-sensitive acid generators 2-4] By appropriately selecting precursors and choosing a formulation similar to that used in Synthesis Example 1 of Radiation-Sensitive Acid Generators, the [B] radiation-sensitive acid generator represented by formulas (B-2) to (B-4) was synthesized.

[0211] [Synthesis Example of Radiation-Sensitive Acid Generator 5] Synthesis of Radiation-Sensitive Acid Generator (B-5) 10.0 mmol of the compound represented by formula (S-3), 10.0 mmol of 4-(pentafluorosulfanyl)benzaldehyde, 1.5 mmol of p-toluenesulfonic acid (p-TsOH), and 120 g of toluene were added to a reaction vessel. A Dean-Stark tube was placed in the reaction vessel, and the solution was stirred under reflux conditions for 8 hours. After the reaction was complete, saturated sodium bicarbonate aqueous solution was added, and dichloromethane was added for extraction. The organic layer was separated and dried over anhydrous sodium sulfate. The solvent was removed by distillation, and the layer was purified by column chromatography to obtain the compound represented by formula (B-5) (hereinafter also referred to as "radiation-sensitive acid generator (B-5)"). The synthesis scheme of acid generator (B-5) is shown below.

[0212] [ka]

[0213] In the above synthesis scheme, TPS+ is a triphenylsulfonium cation.

[0214] [Example 6 of synthesis of radiation-sensitive acid generator] By selecting a precursor and choosing a formulation similar to that in Synthesis Example 5 of the radioactive acid generator, the radioactive acid generator represented by formula (B-6) [B] was synthesized.

[0215] [Synthesis Example of Radiation-Sensitive Acid Generator 7] Synthesis of Radiation-Sensitive Acid Generator (B-7) In a reaction vessel, 22.0 mmol of 4-pentafluorosulfanylbenzoyl chloride, 22.0 mmol of the compound represented by the following formula (S-4), and 140 g of tetrahydrofuran were added and stirred. Subsequently, 25.0 mmol of triethylamine and 2.2 mmol of N,N-dimethylaminopyridine were added and the mixture was stirred at room temperature for 3 hours. After removing the solvent under reduced pressure, 2 M aqueous hydrochloric acid was added, and then dichloromethane was added to separate the organic layer. The organic layer was dried over anhydrous sodium sulfate, and the solvent was removed by distillation to obtain the ester compound. Next, 22.0 mmol of triphenylsulfonium chloride was added to the above ester compound, and a mixture of water and dichloromethane (1:3 (mass ratio)) was added to make a 0.5 M solution. After stirring at room temperature for 1 hour, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over anhydrous sodium sulfate, and the solvent was removed by distillation. By purification by column chromatography, a radiation-sensitive acid generator represented by the following formula (B-7) was obtained. The synthesis scheme for the radiation-sensitive acid generator (B-7) is shown below.

[0216] [ka]

[0217] [Synthesis Example of Radiation-Sensitive Acid Generator 8] Synthesis of Radiation-Sensitive Acid Generator (B-8) 32.0 mmol of 4-pentafluorosulfanylbenzoyl chloride, 35.3 mmol of 4-bromo-3,3,4,4-tetrafluorobutanol, and 150 g of tetrahydrofuran were added to a reaction vessel and stirred under ice cooling. Subsequently, 35.0 mmol of pyridine was added dropwise, and the mixture was stirred at room temperature for 3 hours. After removing the solvent under reduced pressure, 2 M aqueous hydrochloric acid was added, followed by diethyl ether to separate the organic layer. The organic layer was washed twice with water, dried over anhydrous sodium sulfate, and the solvent was removed by distillation. Purification by column chromatography yielded the compound represented by the following formula (S-5).

[0218] Next, 26.0 mmol of the compound represented by formula (S-5) was dissolved in a 1 M solution of acetonitrile and water (1:1 by mass ratio), and then 52.0 mmol of sodium dithionite and 78.0 mmol of sodium bicarbonate were added, and the mixture was reacted at 80°C for 5 hours. The reaction product was extracted with acetonitrile, and after removing the solvent by distillation, a 0.5 M solution was prepared by adding a 3:1 solution of acetonitrile and water. To this solution, 50.0 mmol of hydrogen peroxide and 2.9 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50°C for 7 hours. The reaction product was extracted with acetonitrile, and the solvent was removed by distillation to obtain the sulfonate compound. Next, 26.0 mmol of triphenylsulfonium chloride was added to the above sulfonate compound, and a 1:3 solution of water and dichloromethane was added to prepare a 0.5 M solution. After stirring at room temperature for 1 hour, dichloromethane was added for extraction, and the organic layer was separated. The resulting organic layer was dried over anhydrous sodium sulfate, and the solvent was removed by distillation. Purification by column chromatography yielded a radiation-sensitive acid generator represented by the following formula (B-8). The synthesis scheme for the radiation-sensitive acid generator (B-8) is shown below.

[0219] [ka]

[0220] The radiation-sensitive acid generators used in each example and comparative example are shown below.

[0221] [ka]

[0222] [ka]

[0223] <[D] Synthesis of acid diffusion control agent> [Synthesis Example of Acid Diffusion Control Agent 1] Synthesis of Acid Diffusion Control Agent (D-1) 5.0 mmol of the compound represented by the following formula (S-2), 5.0 mmol of sodium salicylate, 50 g of dichloromethane, and 50 g of ultrapure water were added to a reaction vessel. After stirring at room temperature for 30 minutes, the organic layer was separated. The obtained organic layer was washed with ultrapure water, and the solvent was removed by distillation to obtain the compound represented by the following formula (D-1) (hereinafter also referred to as "acid diffusion control agent (D-1)"). The synthesis scheme of acid diffusion control agent (D-1) is shown below.

[0224] [ka]

[0225] [Example 2 of Acid Diffusion Control Agent Synthesis] By selecting a precursor and choosing a formulation similar to that used in Acid Diffusion Control Agent Synthesis Example 2, the [D] acid diffusion control agent represented by formula (D-2) was synthesized.

[0226] The acid diffusion control agents used in each example and comparative example are shown below.

[0227] [ka]

[0228] [Example 1] A radiation-sensitive resin composition (R-1) was prepared by mixing 100 parts by mass of polymer (A-1), 20 parts by mass of (B-1) as a radiation-sensitive acid generator, 20 mol% of (D-3) as an acid diffusion control agent relative to (B-1) with 4,800 parts by mass of (E-1) and 2,000 parts by mass of (E-2) as organic solvents, and filtering the resulting mixture through a membrane filter with a pore size of 0.20 μm.

[0229] [Examples 2-24 and Comparative Example 1] Radiation-sensitive resin compositions (R-2) to (R-24) and (CR-1) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 2 below were used.

[0230] [Table 2]

[0231] In Table 2, the organic solvents are as follows: E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol 1-monomethyl ether

[0232] <Resist pattern formation> A 12-inch silicon wafer surface, on which an underlayer film with an average thickness of 20 nm (Brewer Science's "AL412") had been formed, was coated with the prepared radiation-sensitive resin composition using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). After soft baking (SB) at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a resist film with an average thickness of 50 nm. Next, this resist film was irradiated with EUV light using an EUV lithography machine (ASML's "NXE3300", NA=0.33, illumination conditions: Conventional s=0.89, mask imecDEFECT32FFR02). The resist film was subjected to post-exposure baking (PEB) at 110°C for 60 seconds. Subsequently, a 2.38 mass% TMAH aqueous solution was used for development at 23°C for 30 seconds to form a positive-type 32 nm line and space pattern.

[0233] <Rating> The LWR performance and process window of each radiation-sensitive resin composition were evaluated by measuring each resist pattern formed as described above according to the method described below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the length of the resist patterns. The evaluation results are shown in Table 3 below.

[0234] [sensitivity] In forming the resist pattern described above, the exposure amount used to form the 32nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as Eop (unit: mJ / cm²). 2) was used. Sensitivity is indicated by the size of the Eop value, with smaller values ​​indicating better sensitivity. Sensitivity is defined as Eop = 30 mJ / cm². 2 In the following cases, it is "A", 30 mJ / cm² 2 If the level is greater than 32 mJ / cm² or less, it is "B", 32 mJ / cm 2 If it exceeded this value, it was rated as "C".

[0235] [LWR performance] The formed resist pattern was observed from above using the scanning electron microscope described above. The line width was measured at 50 arbitrary points, and the 3-sigma value was determined from the distribution of these measurements, which was defined as the LWR (unit: nm). A smaller LWR value indicates less line jitter and better performance. The LWR performance was evaluated as follows: "A" if the LWR was 4.0 nm or less, "B" if it was between 4.0 nm and 4.2 nm, and "C" if it was greater than 4.2 nm.

[0236] [Process window] The "process window" refers to the range of resist dimensions within which a pattern free of bridging defects and collapse can be formed. Patterns were formed from low to high exposure levels using a mask that forms a 32nm line-and-space (1L / 1S) pattern. Generally, defects such as bridging between patterns are observed at low exposure levels, while defects such as pattern collapse are observed at high exposure levels. The difference between the maximum and minimum resist dimensions within which these defects are not observed was defined as the CD (Critical Dimension) margin (in nm). A larger CD margin indicates a wider and better process window. A CD margin of 30nm or more was rated "A", 28nm or more but less than 30nm was rated "B", and less than 28nm was rated "C".

[0237] [Table 3]

[0238] 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, LWR performance, and process window. [Industrial applicability]

[0239] The radiation-sensitive resin composition and resist pattern formation method of the present invention can improve sensitivity, LWR performance, and process window compared to conventional methods. Therefore, these can be suitably used for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A resin comprising repeating unit A having an acid-dissociable group, and repeating unit B containing an organic acid anion moiety and an onium cation moiety, An onium salt containing an organic acid anion moiety and an onium cation moiety, which is liberated from the polymer constituting the above resin, Solvent and Includes, The above organic acid anion portion comprises at least one selected from the group consisting of sulfonic acid anions, carboxylic acid anions, and sulfonimide anions. The above onium salt contains a pentafluorosulfanil group. Radiation sensitive resin composition.

2. The above onium salt is represented by the following formula (A-1) or (A-2), the radiation-sensitive resin composition according to claim 1. 【Chemistry 1】 (In the above formulas (A-1) and (A-2), L １ This is an alkylene group having 1 to 6 carbon atoms, which may be a single bond, an ether bond, or an ester bond, or which may contain an ether bond or an ester bond. R １ is a hydroxyl group, carboxyl group, fluorine atom, chlorine atom, bromine atom, pentafluorosulfanyl group, 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 Or -NR ８ -C(=O)-OR ９ That is the case. R ２ When p is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms, and 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. Rf １ to Rf ４ are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of these is a fluorine atom or a trifluoromethyl group. Further, Rf １ and Rf ２ may combine with each other to form a carbonyl group. 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. Also, R ３ , R ４ and R ５ Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded. p is an integer that satisfies the conditions 1 ≤ p ≤ 3. q and r are integers satisfying 0 ≤ q ≤ 5, 0 ≤ r ≤ 3, and 0 ≤ q + r ≤ 5.

3. The above onium cation portion is represented by the following formula (Q-1), the radiation-sensitive resin composition according to claim 1. 【Chemistry 2】 (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, the multiple Ra1s 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 Ra2 values, the multiple Ra2 values ​​may be the same or different. n ３ n represents an integer from 1 to 5, and n ３ If the number is 2 or more, the multiple Ra3 values ​​may be the same or different. Ra ３ represents a substituent, where at least one Ra ３ This represents a pentafluorosulfanil group. Ra １ and Ra ２ They may be connected to each other to form a ring. 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 If n2 is 1 or greater and n2 is 1 or greater, Ra １ and Ra ２ They may be connected to each other to form a ring.

4. In the above formula (A-1) or (A-2), r is an integer satisfying 1 ≤ r ≤ 3, and at least one R １ The radiation-sensitive resin composition according to claim 2, wherein is a pentafluorosulfanil group.

5. The above onium salt is represented by the following formula (S-1) or (S-2), the radiation-sensitive resin composition according to claim 1. 【Transformation 3】 (In the above formulas (S-1) and (S-2), R １ This may be substituted with a hydrogen atom, a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, a pentafluorosulfanyl group, 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 Or -NR １Ａ -C(=O)-OR １Ｂ That is the case. R １Ａ This is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. R １Ｂ This is an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms. 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. L １ This is a single bond or a divalent linking group having 1 to 20 carbon atoms, and may include an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxyl group, or a carboxyl group. m and n are integers satisfying 0 ≤ m ≤ 5, 0 ≤ n ≤ 3, and 0 ≤ m + n ≤ 5.

6. The above onium cation portion is represented by the following formula (Q-1), the radiation-sensitive resin composition according to claim 5. 【Chemistry 4】 (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 represents a substituent, where at least one Ra ３ This represents a pentafluorosulfanil group. Ra １ and Ra ２ They may be connected to each other to form a ring. 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 If n2 is 1 or greater and n2 is 1 or greater, Ra １ and Ra ２ They may be connected to each other to form a ring.

7. In the above formula (S-1) or (S-2), n is an integer satisfying 1 ≤ n ≤ 3, and at least one R １ The radiation-sensitive resin composition according to claim 5, wherein is a pentafluorosulfanil group.

8. The radiation-sensitive resin composition according to claim 1, wherein the resin contains repeating units D having phenolic hydroxyl groups, and the repeating units D are repeating units represented by the following formula (D). 【Transformation 5】 (In the above formula (D), R α These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L ＣＡ The bonds are single bonds, -COO-*, or -O-. * indicates a bond on the aromatic ring side. R １０１ R is a protecting group that is deprotected by the action of a hydrogen atom or an acid. １０１ If multiple R １０１ They are either identical or different from one another. R １０２ These are cyano groups, nitro groups, alkyl groups, fluorinated alkyl groups, alkoxycarbonyloxy groups, acyl groups, or acyloxy groups. n ｄ３ m is an integer from 0 to 2, and m d3 is an integer from 1 to 8, and m ｄ４ m is an integer between 1 and 8, where 1 ≤ m ｄ３ +m ｄ４ ≤ 2n ｄ３ (Saves +5.)

9. The radiation-sensitive resin composition according to claim 1, wherein the repeating unit A is a repeating unit represented by the following formula (1). 【Transformation 6】 (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.

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

11. The radiation-sensitive resin composition according to claim 2, wherein the above-mentioned organic acid anion portion includes an iodine-substituted aromatic ring structure.

12. The radiation-sensitive resin composition according to claim 5, wherein the above-mentioned organic acid anion portion includes an iodine-substituted aromatic ring structure.

13. 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 12 onto 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.

14. The pattern forming method according to claim 13, wherein the exposure is performed using extreme ultraviolet light or an electron beam.

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