Radiation-sensitive composition, pattern-forming method, and photodecayable base

Abstract

This radiation-sensitive composition contains a polymer having an acid-dissociable group and a compound represented by formula (1). In formula (1), A1 represents a (m+n+2)-valent aromatic ring group. In formula (1), "-OH" and "-COO-" are bound to the same benzene ring in A1. An atom to which "-OH" is bound is located adjacent to an atom to which "-COO-" is bound. R1 represents a monovalent group having a cyclic(thio)acetal structure. M+ represents a monovalent organic cation.

Description

[Technical Field]

[0001] [Cross-reference of related applications] This application claims priority under Japanese Patent Application No. 2022-60692, filed on 31 March 2022, which is incorporated herein by reference in its entirety. This disclosure relates to a radiation-sensitive composition, a pattern-forming method, and a photodecayable base. [Background technology]

[0002] Photolithography, a technique using resist compositions, is employed for the formation of fine circuits in semiconductor devices. A typical procedure for photolithography involves first exposing a film formed from a resist composition (hereinafter also referred to as the "resist film") to radiation through a mask pattern. A chemical reaction involving the acid generated by this exposure creates a difference in the dissolution rate in the developer between the exposed and unexposed areas of the resist film. Subsequently, the resist film is brought into contact with the developer to form a resist pattern on the substrate.

[0003] For example, Patent Document 1 discloses a resist composition containing a polymer having a structural unit containing an acid-dissociable group and a compound having a bulky stereostructure that generates phenolic hydroxyl groups upon exposure. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-203984 [Overview of the project] [Problems that the invention aims to solve]

[0005] In photolithography techniques using resist compositions, miniaturization of patterns is being advanced by utilizing short-wavelength radiation such as ArF excimer lasers, or by employing liquid immersion lithography, a method in which exposure is performed with the space between the lens of the exposure apparatus and the resist film filled with a liquid medium. Furthermore, as a next-generation technology, lithography using even shorter-wavelength radiation such as electron beams, X-rays, and extreme ultraviolet (EUV) is also being considered. In the pursuit of these next-generation technologies, performance equivalent to or better than conventional methods is required in terms of the radiation sensitivity of the resist composition, the LWR (Line Width Roughness) performance, which is an indicator of the variation in the line width of the resist pattern, and the shapeness of the resist pattern (for example, the rectangularity of the cross-sectional shape of the resist pattern).

[0006] This disclosure has been made in view of the above-mentioned problems, and its main purpose is to provide a radiation-sensitive composition and a pattern-forming method that exhibit high sensitivity and excellent LWR performance and pattern shape. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problem and have found that the problem can be solved by using an onium salt compound having a specific structure. Specifically, the following means are provided according to this disclosure.

[0008] This disclosure provides, in one embodiment, a radiation-sensitive composition containing a polymer having an acid-dissociable group and a compound (Q) represented by the following formula (1).

[0009] [ka] (In formula (1), A 1 is an (m+n+2) valent aromatic ring group. In formula (1), "-OH" and "-COO - " is A 1 The atoms bonded to the same benzene ring inside, and to which the "-OH" is bonded, and the "-COO" -is adjacent to the atom to which "]" is attached. R 1 is a monovalent group having a cyclic (thio) acetal structure. m is an integer of 0 or more. When m is 2 or more, a plurality of R 1 are the same as or different from each other. n is an integer of 0 or more. When n is 1, R 2 is a halogen atom or a substituted or unsubstituted monovalent hydrocarbon group. When n is 2 or more, a plurality of R 2 are, independently of each other, a halogen atom, a monovalent hydrocarbon group or a substituted monovalent hydrocarbon group, or two of the plurality of R 2 are combined with each other and represent an alicyclic hydrocarbon structure or an aliphatic heterocyclic structure formed together with the atoms to which they are attached. However, when m is 0, n is 2 or more, and two of the plurality of R 2 are combined with each other and represent a cyclic (thio) acetal structure formed together with the atoms to which they are attached. M + is a monovalent organic cation. )

[0010] In another embodiment, the present disclosure provides a patterning method including a step of applying the above radiation-sensitive composition onto a substrate to form a resist film, a step of exposing the resist film, and a step of developing the exposed resist film.

[0011] In another embodiment, the present disclosure provides a photo-dissociable base represented by the above formula (1).

Advantages of the Invention

[0012] The radiation-sensitive composition of the present disclosure contains the compound (Q) represented by the above formula (1) together with a polymer having an acid-dissociable group, and thus exhibits high sensitivity while exhibiting excellent LWR performance and pattern shape properties during resist pattern formation. Further, according to the patterning method of the present disclosure, since the radiation-sensitive composition of the present disclosure is used, further high-precision and high-quality of a fine resist pattern can be achieved.

Embodiments for Carrying Out the Invention

[0013] The following details the matters related to the implementation of this disclosure. In this specification, numerical ranges indicated using "~" include the numbers indicated before and after "~" as the lower and upper limits, respectively.

[0014] ≪Radiation-sensitive composition≫ The radiation-sensitive composition of this disclosure (hereinafter also referred to as "the Composition") contains a polymer having an acid-dissociable group (hereinafter also referred to as "polymer (A)") and a compound (Q) having a specific anionic structure. Furthermore, the Composition may also contain components other than polymer (A) and compound (Q) (hereinafter also referred to as "optional components"), to the extent that they do not impair the effects of the disclosure. Each component will be described in detail below.

[0015] In this specification, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also include those that have a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may include a linear structure or an alicyclic hydrocarbon structure as part of it. "Organic group" means an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). "(meth)acrylic" means "acrylic" and "methacrylic". "(thio) ether" encompasses both "ether" and "thioether."

[0016] <Polymer (A)> The acid-dissociable groups of polymer (A) are groups that substitute for hydrogen atoms in acidic groups (e.g., carboxyl groups, phenolic hydroxyl groups, alcoholic hydroxyl groups, sulfo groups, etc.) and dissociate under the action of acid. By incorporating a polymer having acid-dissociable groups into a radiation-sensitive composition, the acid-dissociable groups dissociate through a chemical reaction involving acid generated by exposure, producing acidic groups and altering the solubility of the polymer in the developer. As a result, the composition can be given good lithography properties.

[0017] The polymer (A) preferably contains structural units having acid-dissociable groups (hereinafter also referred to as "structural unit (I)"). Examples of structural unit (I) include structural units having a structure in which the hydrogen atoms of a carboxyl group are replaced by substituted or unsubstituted tertiary hydrocarbon groups, structural units having a structure in which the hydrogen atoms of a phenolic hydroxyl group are replaced by substituted or unsubstituted tertiary hydrocarbon groups, and structural units having an acetal structure. From the viewpoint of improving the pattern rectangularity of the composition, structural unit (I) is preferably a structural unit having a structure in which the hydrogen atoms of a carboxyl group are replaced by substituted or unsubstituted tertiary hydrocarbon groups, and specifically, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferred. [ka] (In formula (3), R 11 This is a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or an alkoxyalkyl group. Q 1 R is a single bond or a substituted or unsubstituted divalent hydrocarbon group. 12 R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. 13 and R 14 These are, independently of each other, a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R 13 and R 14 They are combined with each other R 13 and R 14 (This represents a divalent alicyclic hydrocarbon group with 3 to 20 carbon atoms, formed together with the carbon atom to which it is bonded.)

[0018] In equation (3), R 11 From the viewpoint of copolymerization of the monomer that gives structural unit (I-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred. 1 The divalent hydrocarbon group represented is preferably a divalent aromatic ring group, and is preferably a phenylene group or a naphthalene group. 1 If it is a substituted divalent hydrocarbon group, examples of substituents include halogen atoms (such as fluorine atoms).

[0019] R 12 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by include monovalent linear 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. 12 If the substituent is a substituted monovalent hydrocarbon group, examples of substituents include halogen atoms (such as fluorine atoms) and alkoxy groups.

[0020] R 12 ~R 14 Examples of monovalent linear hydrocarbon groups having 1 to 10 carbon atoms represented by R include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, and linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms. Of these, R 12 ~R 14 The monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by is preferably a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms.

[0021] R 12 ~R 14Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include monocyclic saturated alicyclic hydrocarbons, monocyclic unsaturated alicyclic hydrocarbons, or alicyclic polycyclic hydrocarbons having 3 to 20 carbon atoms, from which one hydrogen atom has been removed. Specific examples of these alicyclic hydrocarbons include monocyclic saturated alicyclic hydrocarbons such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; monocyclic unsaturated alicyclic hydrocarbons such as cyclopentene, cyclohexene, cycloheptene, cyclooctane, and cyclodecene; and polycyclic alicyclic hydrocarbons such as bicyclo[2.2.1]heptane (norbornane), bicyclo[2.2.2]octane, and tricyclo[3.3.1.1] 3,7 Decane (adamantane), tetracyclo[6.2.1.1 3,6 .0 2,7 The Dodecane and others can be cited as examples.

[0022] R 12 Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, represented by this formula, include groups obtained by removing one hydrogen atom from an aromatic ring, such as benzene, naphthalene, anthracene, indene, and fluorene.

[0023] From the viewpoint of thoroughly removing development residue and increasing the difference in dissolution contrast between the exposed and unexposed areas in the developer, R 12 Among these, substituted or unsubstituted monovalent hydrocarbon groups having 1 to 8 carbon atoms are preferred, and linear or branched monovalent saturated hydrocarbon groups having 1 to 8 carbon atoms, or monovalent alicyclic hydrocarbon groups having 3 to 8 carbon atoms are more preferred.

[0024] R 13 and R 14 They are combined with each other R 13 and R 14 Examples of divalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms that are formed together with the carbon atom to which they are bonded include groups obtained by removing two hydrogen atoms from the same carbon atom constituting the carbon ring of monocyclic or polycyclic alicyclic hydrocarbons with the above number of carbon atoms. 13 and R 14The divalent alicyclic hydrocarbon group formed by combining these elements may be a monocyclic hydrocarbon group or a polycyclic hydrocarbon group. 13 and R 14 When a divalent alicyclic hydrocarbon group formed by combining these elements is a polycyclic hydrocarbon group, the polycyclic hydrocarbon group may be a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group. Furthermore, the polycyclic hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. A saturated hydrocarbon group is preferred.

[0025] Here, "bridged alicyclic hydrocarbon" refers to a polycyclic alicyclic hydrocarbon in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a bond chain containing one or more carbon atoms. "Condensed alicyclic hydrocarbon" refers to a polycyclic alicyclic hydrocarbon in which multiple alicyclic rings share an edge (a bond between two adjacent carbon atoms).

[0026] Among monocyclic alicyclic hydrocarbon groups (hereinafter also referred to as "monocyclic aliphatic hydrocarbon groups"), saturated hydrocarbon groups are preferably cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, or cyclooctanediyl groups. Unsaturated hydrocarbon groups are preferably cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, or cyclooctenediyl groups. Polycyclic alicyclic hydrocarbon groups (hereinafter also referred to as "polycyclic aliphatic hydrocarbon groups") are preferably bridged alicyclic saturated hydrocarbon groups, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tetracyclo[6.2.1.1 3,6 .0 2,7 ]dodecanediyl group, or tricyclo[3.3.1.1 3,7 It is preferable that the group be a decane-2,2-diyl group (adamantane-2,2-diyl group).

[0027] It is preferable that polymer (A) has a structural unit represented by the following formula (4), as this allows for a greater difference in the dissolution rate in the developer between the exposed and unexposed areas, and enables the formation of finer patterns. [ka] (In formula (4), R 11 This is a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or an alkoxyalkyl group. Q 1 R is a single bond or a substituted or unsubstituted divalent hydrocarbon group. 15 R is a monovalent substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms. 16 and R 17 These are, independently of each other, a monovalent linear hydrocarbon group having 1 to 8 carbon atoms or a monovalent monocyclic aliphatic hydrocarbon group having 3 to 8 carbon atoms, or R 16 and R 17 They are combined with each other R 16 and R 17 (This represents a divalent monocyclic aliphatic hydrocarbon group with 3 to 8 carbon atoms, formed together with the carbon atom to which it is bonded.)

[0028] In equation (4), R 11 From the viewpoint of copolymerization of monomers that give structural units represented by formula (4), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred. 1 Specific and preferred examples are Q in formula (3). 1 Examples of similar elements to those exemplified above include the base.

[0029] R 15 , R 16 and R 17 A concrete example of this is R in equation (3) above. 12 , R 13 and R 14 The examples of corresponding carbon numbers in the explanation can be used. Of these, R 15 The carbon group is preferably a monovalent saturated hydrocarbon group having 1 to 5 carbon atoms in a linear or branched configuration, or a monovalent alicyclic hydrocarbon group having 3 to 8 carbon atoms, and more preferably a monovalent monocyclic aliphatic hydrocarbon group having 1 to 3 carbon atoms in a linear or branched configuration, or a monovalent monocyclic aliphatic hydrocarbon group having 3 to 5 carbon atoms. 16 and R 17 is a linear or branched monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, or R 16 and R17 They are combined with each other R 16 and R 17 It is preferable to represent a divalent monocyclic aliphatic hydrocarbon group having 3 to 8 carbon atoms, which is composed of the carbon atoms to which it is bonded.

[0030] The structural unit represented by formula (4) above is, in particular, R 15 is an alkyl group having 1 to 4 carbon atoms, and R 16 and R 17 However, R 16 and R 17 Preferably, these are cycloalkanediyl groups having 3 to 6 carbon atoms, which are formed when these are combined with each other and bonded together with the carbon atoms.

[0031] Specific examples of structural units (I) include, for instance, the structural units represented by the following formulas (3-1) to (3-7). [ka] (In formulas (3-1) to (3-7), R 11 ~R 14 This is equivalent to equation (3) above. i and j are independent integers between 0 and 4. h and g are independent 0 or 1.

[0032] In formulas (3-1) to (3-7), i and j are preferably 1 or 2, and more preferably 1. h and g are preferably 1. 12 A methyl group, an ethyl group, or an isopropyl group is preferred. 13 and R 14 A methyl group or an ethyl group is preferred.

[0033] The content of structural unit (I) is preferably 10 mol% or more, more preferably 25 mol% or more, and even more preferably 35 mol% or more, relative to the total structural units constituting polymer (A). Furthermore, the content of structural unit (I) is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less, relative to the total structural units constituting polymer (A). By setting the content of structural unit (I) within the above range, the LWR performance, the CDU (Critical Dimension Uniformity) performance (an indicator of the uniformity of line width and hole diameter), and the pattern shape of this composition can be further improved.

[0034] When polymer (A) has a structural unit (I) represented by the above formula (4), the content of the structural unit represented by the above formula (4) is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 25 mol% or more, relative to the total structural units constituting polymer (A). By setting the content of the structural unit represented by the above formula (4) within the above range, the difference in dissolution rate in the developer between the exposed and unexposed areas can be made larger, making it possible to form a finer pattern. Polymer (A) may have only one type of structural unit (I), or it may contain a combination of two or more types.

[0035] [Other structural units] Polymer (A) may further contain structural units different from structural unit (I) (hereinafter also referred to as "other structural units") along with structural unit (I). Examples of other structural units include structural unit (II) and structural unit (III) below.

[0036] • Structural Unit (II) The polymer (A) may further contain a structural unit having a polar group (hereinafter also referred to as "structural unit (II)"). By including the structural unit (II) in the polymer (A), it becomes easier to further adjust the solubility of the polymer (A) in the developing solution, and it is possible to improve lithography performance such as resolution. Examples of the structural unit (II) include a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure (hereinafter also referred to as "structural unit (II-1)"), and a structural unit having a monovalent polar group (hereinafter also referred to as "structural unit (II-2)").

[0037] · Structural unit (II-1) By introducing the structural unit (II-1) into the polymer (A), it is possible to adjust the solubility of the polymer (A) in the developing solution, improve the adhesion of the resist film, or further improve the etching resistance. Examples of the structural unit (II-1) include, for example, structural units represented by the following formulas (6-1) to (6-10). [Chemical formula] (In formulas (6-1) to (6-10), R L1 is a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or an alkoxyalkyl group. R L2 and R L3 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. R L4 and R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group, or R L4 and R L5 are combined with each other to form a divalent alicyclic hydrocarbon group having 3 to 8 carbon atoms together with the carbon atom to which R L4 and R L5 are attached. L 5is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. p is an integer from 0 to 3. q is an integer from 1 to 3.)

[0038] R L4 and R L5 are combined with each other to form a divalent alicyclic hydrocarbon group having 3 to 8 carbon atoms together with the carbon atom to which R L4 and R L5 is bonded. Examples of the divalent alicyclic hydrocarbon group include those having 3 to 8 carbon atoms among the descriptions of R 13 and R 14 above. One or more hydrogen atoms on this alicyclic hydrocarbon group may be substituted with a hydroxy group.)

[0039] L 5 Examples of the divalent linking group represented by include a linear or branched divalent chain hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH- and -S-.

[0040] The structural unit (II-1) is preferably a structural unit represented by formula (6-2), formula (6-4), formula (6-6), formula (6-7) or formula (6-10) among formulas (6-1) to (6-10).

[0041] When the polymer (A) has the structural unit (II-1), the content ratio of the structural unit (II-1) is preferably 80 mol% or less, more preferably 70 mol% or less, and still more preferably 65 mol% or less, based on all the structural units constituting the polymer (A). Also, when the polymer (A) has the structural unit (II-1), the content ratio of the structural unit (II-1) is preferably 2 mol% or more, more preferably 5 mol% or more, and still more preferably 10 mol% or more, based on all the structural units constituting the polymer (A). By setting the content ratio of the structural unit (II-1) within the above range, the lithography performance such as resolution in the present composition can be further improved.)

[0042] · Structural unit (II-2) Structural unit (II-2) may be introduced into polymer (A) to adjust the solubility of polymer (A) in the developer to improve the lithography performance of the composition, such as resolution. Examples of polar groups that structural unit (II-2) may have include hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and sulfonamide groups. Of these, hydroxyl groups and carboxyl groups are preferred, and hydroxyl groups (especially alcoholic hydroxyl groups) are more preferred. Note that structural unit (II-2) is a different structural unit from the structural unit (structural unit (III)) having a phenolic hydroxyl group, which will be described below.

[0043] Herein, in this specification, "phenolic hydroxyl group" refers to a group to which a hydroxyl group is directly bonded to an aromatic hydrocarbon structure. "Alcoholic hydroxyl group" refers to a group to which a hydroxyl group is directly bonded to an aliphatic hydrocarbon structure. In an alcoholic hydroxyl group, the aliphatic hydrocarbon structure to which the hydroxyl group is bonded may be a chain hydrocarbon group or an alicyclic hydrocarbon group.

[0044] Examples of structural units (II-2) include structural units represented by the following formula. However, structural units (II-2) are not limited to these. [ka] (In the formula, R A (This is a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or an alkoxyalkyl group.)

[0045] When polymer (A) has structural unit (II-2), the content of structural unit (II-2) is preferably 2 mol% or more, and more preferably 5 mol% or more, relative to the total structural units constituting polymer (A). Furthermore, the content of structural unit (II-2) is preferably 30 mol% or less, and more preferably 25 mol% or less, relative to the total structural units constituting polymer (A). By setting the content of structural unit (II-2) within the above range, the lithography performance, such as resolution, of this composition can be further improved.

[0046] • Structural Unit (III) Polymer (A) may further have structural units having phenolic hydroxyl groups (hereinafter also referred to as "structural unit (III)"). Polymer (A) having structural unit (III) is preferable because it can improve etching resistance and the difference in developer solubility between exposed and unexposed areas (solubility contrast).

[0047] In particular, polymer (A) having structural unit (III) can be preferably used in pattern formation using exposure with radiation of wavelength 50 nm or less, such as electron beams or EUV. When applied to pattern formation using exposure with radiation of wavelength 50 nm or less, polymer (A) is preferably having structural unit (III).

[0048] Structural unit (III) is not particularly limited as long as it contains a phenolic hydroxyl group. Specific examples of structural unit (III) include structural units derived from hydroxystyrene or its derivatives, and structural units derived from (meth)acrylic compounds having a hydroxybenzene structure.

[0049] When obtaining a polymer (A) having structural unit (III), polymerization may be carried out with the phenolic hydroxyl group protected by an alkali-dissociable group or the like, and then hydrolysis may be performed to deprotect it, thereby making polymer (A) have structural unit (III). The structural unit that gives structural unit (III) by hydrolysis is preferably at least one selected from the group consisting of the structural unit represented by the following formula (7-1) and the structural unit represented by the following formula (7-2). [ka] (In equations (7-1) and (7-2), R P1 is a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or an alkoxyalkyl group. 3 R is a substituted or unsubstituted divalent aromatic ring group. P2 (This refers to a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms.)

[0050] A 3 The aromatic ring group represented by is a group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a hydrocarbon ring, for example, aromatic hydrocarbon rings such as benzene, naphthalene, and anthracene. Of these, A 3 The group is preferably one obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted benzene or naphthalene, and more preferably a substituted or unsubstituted phenylene group. Examples of substituents include halogen atoms such as fluorine atoms.

[0051] R P2 As a monovalent hydrocarbon group having 1 to 20 carbon atoms, the R in structural unit (I) is 12 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include those exemplified above. Examples of alkoxy groups include methoxy, ethoxy, and tert-butoxy groups. P2 These are preferably alkyl groups or alkoxy groups, and among them, methyl groups or tert-butoxy groups are preferred.

[0052] When obtaining a radiation-sensitive composition for exposure with radiation of a wavelength of 50 nm or less, the content of structural unit (III) in polymer (A) is preferably 15 mol% or more, and more preferably 20 mol% or more, relative to the total structural units constituting polymer (A). Furthermore, the content of structural unit (III) in polymer (A) is preferably 65 mol% or less, and more preferably 60 mol% or less, relative to the total structural units constituting polymer (A).

[0053] Other structural units include, in addition to those mentioned above, structural units derived from styrene, vinylnaphthalene, monomers having an alicyclic structure (such as 1-adamantyl methacrylate), and n-pentyl (meth)acrylate. The content ratio of these other structural units can be appropriately set according to each structural unit, as long as it does not impair the effects of this disclosure.

[0054] Synthesis of polymer (A) Polymer (A) can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0055] Examples of radical polymerization initiators include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobisisobutyrate; and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl-2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical initiators can be used individually or in combination of two or more.

[0056] Examples of solvents used in polymerization include alkanes, cycloalkanes, aromatic hydrocarbons, halogenated hydrocarbons, saturated carboxylic acid esters, ketones, ethers, and alcohols. Specific examples of these include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylenedibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. The solvent used in the polymerization described above may be a single solvent or a combination of two or more solvents.

[0057] The reaction temperature in polymerization is typically 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is typically 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0058] The weight-average molecular weight (Mw) of polymer (A) in terms of polystyrene, 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 even more preferably 4,000 or more. Furthermore, the Mw of polymer (A) is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and even more preferably 15,000 or less. Setting the Mw of polymer (A) within the above range is advantageous in that it improves the coating properties of the composition, improves the heat resistance of the resulting resist film, and sufficiently suppresses development defects.

[0059] The ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) (Mw / Mn) of polymer (A) by GPC is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. Furthermore, Mw / Mn is usually 1.0 or higher.

[0060] In this composition, the content of polymer (A) is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, based on the total amount of solids contained in this composition (i.e., the total mass of components other than solvent components contained in this composition). Furthermore, the content of polymer (A) is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less, based on the total amount of solids contained in this composition. It is preferable that polymer (A) constitutes the base resin of this composition. In this specification, "base resin" refers to a polymer component that accounts for 50% by mass or more of the total amount of solids contained in this composition. This composition may contain only one type of polymer (A) or two or more types.

[0061] <Compound (Q)> Compound (Q) is a compound represented by the following formula (1). [ka] (In formula (1), A 1 is an (m+n+2) valent aromatic ring group. In formula (1), "-OH" and "-COO - " is A 1 The atoms bonded to the same benzene ring inside, and to which the "-OH" is bonded, and the "-COO" - The atom to which it bonds is adjacent. 1 is a monovalent group having a cyclic (thio)acetal structure. m is a non-negative integer. If m is 2 or greater, multiple R 1 They are either identical or different from each other. n is a non-negative integer. If n is 1, R 2 is a halogen atom or a substituted or unsubstituted monovalent hydrocarbon group. If n is 2 or more, multiple R 2These are, independently of each other, a halogen atom, a monovalent hydrocarbon group, or a substituted monovalent hydrocarbon group, or multiple R 2 Two of these atoms are combined with each other to form an alicyclic hydrocarbon structure or an aliphatic heterocyclic structure with the atoms they bond to. However, if m is 0, n is 2 or greater, and there are multiple R 2 Two of these represent a cyclic (thio)acetal structure, which is formed when they are combined with the atoms to which they bond. + (This is a monovalent organic cation.)

[0062] Compound (Q) can function as a photodecayable base, a type of acid diffusion control agent. Photodecayable bases are components that suppress chemical reactions caused by acids in unexposed areas by inhibiting the diffusion of acids generated in the resist film during exposure. By including compound (Q) together with polymer (A), this composition exhibits high sensitivity while demonstrating excellent LWR and CDU performance during resist pattern formation. Furthermore, this composition enables the formation of resist patterns with good rectangular and circular properties.

[0063] Here, the acid generated by exposure to a photodecayable base is an acid that does not induce the dissociation of acid-dissociable groups under normal conditions. "Normal conditions" here refers to the conditions for performing a post-exposure bake (PEB) at 110°C for 60 seconds. In unexposed areas, the photodecayable base exhibits an acid diffusion inhibitory effect due to its basicity, while in exposed areas, the decomposition of cations produces protons and anions, generating a weak acid, thus reducing the acid diffusion inhibitory effect. Therefore, in a resist film containing a photodecayable base, in the exposed areas, the acid generated by exposure works efficiently, causing the acid-dissociable groups of polymer (A) to dissociate. On the other hand, in unexposed areas, no changes in the components of the resist film due to the acid occur. Therefore, the difference in solubility between the exposed and unexposed areas becomes more clearly apparent. Because this composition contains compound (Q), acid diffusion in the unexposed areas is sufficiently suppressed, resulting in high sensitivity, excellent LWR and CDU performance, and superior shapeability of the resulting resist pattern.

[0064] · About Anions In the above equation (1), A 1 The (m+n+2) valent aromatic ring group represented by is a group obtained by removing (m+n+2) hydrogen atoms from an aromatic ring. The aromatic ring is preferably a hydrocarbon ring, and examples include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, phenanthrene, indene, fluorene, tetracene, and pyrene. Of these, A 1 The group is preferably one obtained by removing (m+n+2) hydrogen atoms from benzene, naphthalene, or anthracene, and more preferably one obtained by removing (m+n+2) hydrogen atoms from benzene.

[0065] A 1 The benzene ring inside contains "-OH" and "-COO" - The two terms "-OH" and "-COO" are directly joined together. - The elements are introduced in adjacent positions. That is, A 1 In the benzene ring inside, the atom to which "-OH" is bonded and "-COO" - The atom to which it bonds is adjacent. For example, A 1 If it is a group obtained by removing (m+n+2) hydrogen atoms from naphthalene, then "-OH" and "-COO" - These atoms are bonded to adjacent carbon atoms in one of the two benzene rings that make up naphthalene.

[0066] R 1This is a monovalent group having a cyclic (thio)acetal structure. In this specification, "cyclic (thio)acetal structure" encompasses both cyclic acetal structures and cyclic thioacetal structures. A cyclic thioacetal structure may be a cyclic monothioacetal structure or a cyclic dithioacetal structure. Here, a "cyclic acetal structure" has a ring structure that contains two ether bonds constituting an acetal structure within the same ring, and under acidic conditions, it generates an aldehyde structure or a ketone structure and a diol structure. A "cyclic thioacetal structure" has a ring structure that contains two thioether bonds (one thioether bond and one ether bond in the case of a monothioacetal structure) constituting a thioacetal structure within the same ring. Under acidic conditions, a cyclic thioacetal structure generates a structure in which the corresponding oxygen atom in the description of a cyclic acetal structure is replaced by a sulfur atom. Note that "acidic conditions" means any condition in which the system is acidic, for example, the pH may be less than 7.0 or 6.0 or less.

[0067] R 1 It is not particularly limited as long as it has a cyclic (thio)acetal structure. 1 It is preferable that the group is represented by the following formula (r-1). [ka] (In formula (r-1), X 1 L is a single bond, an ether group, a thioether group, an ester group, a thioester group, or an amide group. 1 This is a single bond or a substituted or unsubstituted divalent hydrocarbon group. 1 This is a group obtained by removing one hydrogen atom from the structure represented by the following formula (w-1). (* represents a bond.) [ka] (In formula (w-1), Y 1 and Y 2 These are, independently of each other, an oxygen atom or a sulfur atom. 3 and R 4These are, independently of each other, a hydrogen atom, a halogen atom, or a monovalent organic group, or R 3 and R 4 R represents an alicyclic hydrocarbon structure formed by combining these elements with the carbon atoms to which they are bonded. 5 and R 6 Each of these is either a hydrogen atom, a halogen atom, or a monovalent organic group, or one of the r R atoms present in the formula. 5 and r R 6 This represents a ring structure formed when any two of the atoms are combined with each other and bonded together with the carbon atoms. r is an integer between 2 and 8. Multiple Rs are shown. 5 They are the same or different, multiple R 6 They are either the same or different.

[0068] In the above equation (r-1), X 1 From the viewpoint of ease of synthesis of compound (Q), an ether group, thioether group, ester group, thioester group, or amide group is preferred.

[0069] L 1 However, in the case of a substituted or unsubstituted divalent hydrocarbon group, examples of such hydrocarbon groups include divalent chain hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms. Specific examples of these include R in formula (3) above. 12 Examples of groups obtained by removing one more hydrogen atom from the monovalent hydrocarbon group exemplified in the explanation include L. 1 The divalent hydrocarbon group represented by is preferably a divalent linear hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and more preferably a linear or branched alkanediyl group, cyclohexylene group, or phenylene group having 1 to 4 carbon atoms.

[0070] L 1 If the compound has substituents, examples of such substituents include halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.) and hydroxyl groups.

[0071] X 1 is an ether group, thioether group, -CO-O-* 1 or -CO-S-* 1 In the case of "* 1 " is L 1 (Represents a coupling with), L 1 The group is preferably a divalent chain hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms; more preferably an alkanediyl group, cyclohexylene group, or phenylene group having 1 to 4 carbon atoms; and even more preferably an alkanediyl group or phenylene group having 1 or 2 carbon atoms. 1 is a single bond, amide group, -O-CO-* 1 or -S-CO-* 1 In the case of L 1 Preferably, the group is a single bond, a divalent chain hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms; more preferably, a single bond, an alkanediyl group having 1 to 4 carbon atoms, a cyclohexylene group, or a phenylene group; and even more preferably, a single bond, an alkanediyl group having 1 or 2 carbon atoms, or a phenylene group.

[0072] W 1 R is a group obtained by removing one hydrogen atom from the structure represented by the above formula (w-1). In the above formula (w-1), 3 , R 4 , R 5 and R 6 Examples of halogen atoms represented by R include fluorine, chlorine, bromine, and iodine atoms. 3 , R 4 , R 5 and R 6 Examples of monovalent organic groups represented by include substituted or unsubstituted monovalent hydrocarbon groups, and monovalent groups obtained by replacing any methylene group in a substituted or unsubstituted hydrocarbon group with an ether group, thioether group, ester group, thioester group, or amide group.

[0073] R 3 , R 4 , R 5 and R 6If is a monovalent hydrocarbon group, then the R in formula (3) above is the monovalent hydrocarbon group. 12 Examples of monovalent hydrocarbon groups are given in the description. These hydrocarbon groups preferably have 1 to 15 carbon atoms, and more preferably 1 to 10 carbon atoms. 3 , R 4 , R 5 and R 6 If R has substituents, examples of substituents include halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), hydroxyl groups, oxo groups, acetyl groups, etc. 3 , R 4 , R 5 or R 6 If the monovalent hydrocarbon group represented is an alicyclic hydrocarbon group or an aromatic hydrocarbon group, a chain-like hydrocarbon group (such as an alkyl group) may be bonded to the ring of these groups.

[0074] R 3 and R 4 The alicyclic hydrocarbon structure formed by combining these atoms with the carbon atoms to which they are bonded may be a monocyclic hydrocarbon structure or a polycyclic hydrocarbon structure. Furthermore, the polycyclic hydrocarbon structure may be a bridged alicyclic hydrocarbon structure or a condensed alicyclic hydrocarbon structure. Moreover, the monocyclic and polycyclic hydrocarbon structures may be saturated hydrocarbon structures or unsaturated hydrocarbon structures. A saturated hydrocarbon structure is preferred. 3 and R 4 A specific example of an alicyclic hydrocarbon structure formed by combining these elements is R in formula (3) above. 13 and R 14 Examples include the divalent alicyclic hydrocarbon group exemplified in the explanation.

[0075] The r Rs present in equation (w-1) 5 and r R 6 Examples of ring structures formed when any two of these atoms are combined with the carbon atoms to which they are bonded include alicyclic hydrocarbon structures, aliphatic heterocyclic structures, and aromatic hydrocarbon structures. Examples of alicyclic hydrocarbon structures include R 3 and R 4The explanation applies. That is, r R 5 and r R 6 A specific example of an alicyclic hydrocarbon structure formed by combining any two of the above is R in formula (3) above. 13 and R 14 Examples include the divalent alicyclic hydrocarbon group exemplified in the explanation.

[0076] r R 5 and r R 6 Any two of these can be combined with each other to form an aliphatic heterocyclic structure, which together with the carbon atoms they bond to may be a monocyclic or polycyclic structure, and may also be a bridged structure, a fused cyclic structure, or a spirocyclic structure. 5 and r R 6 The aliphatic heterocyclic structure formed by combining any two of these elements may be a combination of two or more of the following: bridged structures, fused ring structures, and spiro-ring structures. Here, "spiro-ring structure" refers to a polycyclic cyclic structure in which two rings share one atom. Specific examples of such aliphatic heterocyclic structures include cyclic ether structures, cyclic (thio)acetal structures, lactone structures, cyclic carbonate structures, and sultone structures.

[0077] r R 5 and r R 6 Examples of aromatic hydrocarbon structures formed by any two of these being combined with the carbon atoms they bond to include benzene ring structures and naphthalene ring structures. Of these, the benzene ring structure is preferred. Also, the r R atoms present in formula (w-1) 5 and r R 6 Any two of these atoms can be combined with each other to form a ring structure with the carbon atom to which they are bonded, and this ring structure may have substituents. Examples of substituents include halogen atoms, alkyl groups, alkoxy groups, hydroxyl groups, oxo groups, acetyl groups, acetoxy groups, acetoxyalkyl groups, and the like.

[0078] r is preferably 2 to 6, and more preferably 2 to 4. Y1 and Y 2 An oxygen atom is preferred.

[0079] The position of the hydrogen atom removed from the structure represented by the above formula (w-1) is not particularly limited. 1 A preferred specific example of this is a group represented by the following formula (w1-1) or formula (w1-2). [ka] (In formula (w1-1), Y 1 , Y 2 , R 3 , R 4 And r are synonymous with equation (w-1). There are r R in the equation. 5x and r R 6x It satisfies either (i) or (ii) below. (i) r R 5x and r R 6x One of them is L 1 This represents a bond between two atoms, and the remaining atoms are independently hydrogen atoms, halogen atoms, or monovalent organic groups. (ii) r R 5x and r R 6x Any two of these can be combined to form a ring structure with the carbon atoms to which they are bonded, and the ring structure is L 1 It has a bonding relationship with r R 5x and r R 6x The remaining atoms are, independently of each other, hydrogen atoms, halogen atoms, or monovalent organic groups. [ka] (In formula (w1-2), Y 1 , Y 2 , R 4 , R 5 , R 6 And r are equivalent to equation (w-1). "*" is L 1 (This represents a combination of two elements.)

[0080] Further specific examples of the monovalent group represented by the above formula (w1-1) include the structure represented by the following formula. [ka] (In equations (w1-1-1) and (w1-1-2), Y 1 , Y 2 , R 3 and R 4 This is equivalent to equation (w-1). 5a , R 5b , R 5c , R 5d , R 6a , R 6c and R 6d These are, independently of each other, a hydrogen atom, a halogen atom, or a monovalent organic group. m is a substituted or unsubstituted trivalent alicyclic hydrocarbon group or aliphatic heterocyclic group. t1 is an integer from 1 to 7. t2 and t3 are independent integers from 0 to 3. "*" represents L 1 (This represents a combination of two elements.)

[0081] In the above equations (w1-1-1) and (w1-1-2), R 5a , R 5b , R 5c , R 5d , R 6a , R 6c or R 6d Specific examples of halogen atoms and monovalent organic groups represented by the above formula (w-1) include R 5 , R 6 The base mentioned as an example is a concrete example of this. R m Specific examples of alicyclic hydrocarbon groups and aliphatic heterocyclic groups represented by formula (w-1) include R 5 , R 6 Examples of groups having alicyclic hydrocarbon structures and aliphatic heterocyclic structures are given in the explanation. t1 is preferably 1 to 5, and more preferably 1 to 3. t2 and t3 are preferably 0 to 2, and more preferably 0 or 1.

[0082] In the above equation (1), R 2Specific examples of when R is a halogen atom include fluorine, chlorine, bromine, and iodine atoms. 2 A specific example of a case where is a monovalent hydrocarbon group is R in formula (3) above. 12 The monovalent hydrocarbon group exemplified in the explanation is an example. 2 The monovalent hydrocarbon group represented by preferably has 1 to 15 carbon atoms, and more preferably has 1 to 10 carbon atoms. 2 The monovalent hydrocarbon group represented by is preferably a chain hydrocarbon group having 1 to 10 carbon atoms, and more preferably a saturated chain hydrocarbon group having 1 to 5 carbon atoms. 2 When the substituent is a substituted monovalent hydrocarbon group, examples of substituents include halogen atoms, hydroxyl groups, oxo groups, etc.

[0083] R 2 If is a monovalent group, R 2 Of the above, halogen atoms or alkanediyl groups having 1 to 5 carbon atoms are preferred, halogen atoms are more preferred, and fluorine atoms or iodine atoms are even more preferred.

[0084] 2 R 2 When these are combined with each other to represent an alicyclic hydrocarbon structure or an aliphatic heterocyclic structure formed with the atoms to which they bond, the alicyclic hydrocarbon structure and the aliphatic heterocyclic structure are represented as R in formula (w-1). 5 and R 6 Examples of alicyclic hydrocarbon structures and aliphatic heterocyclic structures are given in the explanation.

[0085] m is preferably 0 to 4, more preferably 0 to 3, even more preferably 0 to 2, and even more preferably 1 or 2. n is preferably 0 to 4, more preferably 0 to 3, and even more preferably 0 or 1. When m is 0, n is 2 or more, and there are multiple R 2 Two of them represent a cyclic (thio)acetal structure, which is formed by combining them with the atoms to which they bond. 2 A specific example of an anionic structure when these elements are combined to form a cyclic (thio)acetal structure is the structure represented by the following formula (r-2). [ka] (In formula (r-2), Y 1 , Y 2 , R 3 and R 4 This is equivalent to equation (w-1). A 2 is a tetravalent aromatic ring group. In formula (r-2), "-OH" and "-COO - " is A 2 The atoms bonded to the same benzene ring inside, and to which the "-OH" is bonded, and the "-COO" - The atom to which it bonds is adjacent. 5e , R 5f , R 6e and R 6f (Each element is independently a hydrogen atom, a halogen atom, or a monovalent organic group. T4 and T5 are independently integers between 0 and 3.)

[0086] In the above equation (r-2), R 5e , R 5f , R 6e or R 6f Specific examples of halogen atoms and monovalent organic groups represented by the above formula (w-1) include R 5 , R 6 The base exemplified as a concrete example is R. 3 and R 4 At least one of these preferably has a ring structure, and more preferably has an alicyclic hydrocarbon structure or an aliphatic heterocyclic structure. Specific examples of alicyclic hydrocarbon structures and aliphatic heterocyclic structures include R in formula (w-1). 5 and R 6 Examples include the alicyclic hydrocarbon structure and aliphatic heterocyclic structure described in the explanation. A 2 A specific example of an aromatic ring group represented by the above formula (1) is A 1 The group exemplified above is a specific example. Preferably, it is a group obtained by removing four hydrogen atoms from benzene or naphthalene. t4 and t5 are preferably 0 to 2, and more preferably 0 or 1.

[0087] • About cations In the above equation (1), M + It is a monovalent cation. In terms of being able to form a resist film with higher LWR and CDU performance, M + The sulfonium cation or iodonium cation is preferred. Specific examples of sulfonium cations include those represented by formulas (X-1), (X-2), (X-3), or (X-4) below. Specific examples of iodonium cations include those represented by formulas (X-5) or (X-6) below. [ka]

[0088] In formula (X-1), R a1 , R a2 and R a3 These are, independently of each other, substituted or unsubstituted C1-C12 alkyl groups, alkoxy groups, alkylcarbonyloxy groups or cycloalkylcarbonyloxy groups, C3-C12 monocyclic or polycyclic cycloalkyl groups, C6-C12 monovalent aromatic hydrocarbon groups, hydroxyl groups, halogen atoms, -OSO2-R P , -SO2-R Q , -SR T is or R a1 , R a2 and R a3 This represents a ring structure formed by combining two or more of the above. This ring structure may include heteroatoms (such as oxygen or sulfur atoms) between the carbon-carbon bonds that form the skeleton. P , R Q and R T k1, k2, and k3 are, independently of each other, substituted or unsubstituted C1-C12 alkyl groups, substituted or unsubstituted C5-C25 monovalent alicyclic hydrocarbon groups, or substituted or unsubstituted C6-C12 monovalent aromatic hydrocarbon groups. k1, k2, and k3 are, independently of each other, integers from 0 to 5. a1 ~R a3 R P , R Q and R T If each of them is multiple, then multiple Ra1 ~R a3 R P , R Q and R T They are either identical or different from each other. a1 , R a2 and R a3 If it has substituents, the substituents are a hydroxyl group, a halogen atom, a carboxyl group, a protected hydroxyl group, a protected carboxyl group, -OSO2-R P , -SO2-R Q , -SR T That's fine.

[0089] In formula (X-2), R b1 This is a substituted or unsubstituted C1-C20 alkyl or alkoxy group, a substituted or unsubstituted C2-C8 acyl group, or a substituted or unsubstituted C6-C8 monovalent aromatic hydrocarbon group, halogen atom, or hydroxyl group. k n is either 0 or 1. k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer from 0 to 7. b1 If there are multiple, then multiple R b1 They are the same or different, multiple R b1 R may represent a ring structure formed by combining with other elements. b2 This is a substituted or unsubstituted alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 or 7 carbon atoms. C k5 is a single bond or a divalent linking group. k5 is an integer from 0 to 4. b2 If there are multiple, then multiple R b2 They are the same or different, and also multiple R b2 may represent a ring structure formed by combining with each other. q is an integer from 0 to 3. In the formula, S + The ring structure containing the carbon atoms may also contain heteroatoms (such as oxygen atoms or sulfur atoms) between the carbon-carbon bonds that form the skeleton.

[0090] In formula (X-3), R c1 , R c2 and R c3These are, independently of each other, substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms.

[0091] In formula (X-4), R g1 This is a substituted or unsubstituted C1-C20 alkyl or alkoxy group, a substituted or unsubstituted C2-C8 acyl group, or a substituted or unsubstituted C6-C8 aromatic hydrocarbon group, or a hydroxyl group. k2 n is either 0 or 1. k2 When k10 is 0, k10 is an integer from 0 to 4, and n k2 When k10 is 1, k10 is an integer from 0 to 7. g1 If there are multiple, then multiple R g1 They are the same or different, and also multiple R g1 R may represent a ring structure formed by combining with other elements. g2 and R g3 These are, independently of each other, a substituted or unsubstituted C1-C12 alkyl group, alkoxy group or alkoxycarbonyloxy group, a substituted or unsubstituted C3-C12 monocyclic or polycyclic cycloalkyl group, a substituted or unsubstituted C6-C12 aromatic hydrocarbon group, a hydroxyl group, a halogen atom, or R g2 and R g3 This represents a ring structure formed by combining these elements. k11 and k12 are independent integers between 0 and 4. g2 is and R g3 If each of them is multiple, then multiple R g2 is and R g3 Each is either identical or different from the others.

[0092] In formula (X-5), R d1 and R d2 k6 and k7 are independent integers from 0 to 5. d1 and Rd2 When there are a plurality of each, a plurality of R d1 and R d2 are each the same or different.

[0093] In formula (X-6), R e1 and R e2 are, independently of each other, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each an integer from 0 to 4 independently of each other.

[0094] M + Specific examples of the sulfonium cation and iodonium cation represented by include, for example, structures represented by the following formulas. However, it is not limited to these specific examples.

Chemical formula

Chemical formula

Chemical formula

[0095]

Chemical formula

[0096] Among these, the compound (Q) is preferably a sulfonium salt, and more preferably a triarylsulfonium salt. As the compound (Q), one kind can be used alone or in combination of two or more kinds.

[0097] Specific examples of the compound (Q) include compounds represented by the following formulas (1-1) to (1-42).

Chemical formula

Chemical formula

[0098] The content of compound (Q) in this composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, per 100 parts by mass of polymer (A). Furthermore, the content of compound (Q) is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, per 100 parts by mass of polymer (A). By setting the content of compound (Q) within the above ranges, the LWR performance, CDU performance, and pattern shape characteristics of this composition can be improved, and the lithography performance can be further enhanced. Compound (Q) can be used alone or in combination of two or more types.

[0099] <Synthesis of compound (Q)> Compound (Q) can be synthesized by appropriately combining standard organic chemistry methods, as shown in the examples described later. For example, a compound having the structure represented by the above formula (w1-1) as a cyclic acetal structure can be synthesized by combining a halogen compound having the structure represented by the above formula (w1-1) with "HO-A 1 (COOR X Compounds represented by )(OH) (where R X It can be synthesized by reacting a monovalent hydrocarbon group with a suitable solvent, optionally in the presence of a catalyst, then hydrolyzing the resulting intermediate product, and finally reacting it with a sulfonium chloride, sulfonium bromide, etc., that yields the onium cation moiety. Furthermore, compounds having the structure represented by the above formula (w1-2) are called "R Y -CO-A 1 (COOR X Compounds represented by )(OH) (where R X R is a monovalent hydrocarbon group, YCompound (Q) can be synthesized by reacting a hydrogen atom or a monovalent hydrocarbon group with a diol compound in a suitable solvent, optionally in the presence of a catalyst, then hydrolyzing the resulting intermediate product, and finally reacting it with a sulfonium chloride, sulfonium bromide, or the like that yields the onium cation moiety. However, the method of synthesizing compound (Q) is not limited to the above.

[0100] <Optional ingredients> This composition may contain polymer (A) and compound (Q), as well as components other than polymer (A) and compound (Q) (optional components). Examples of optional components that this composition may contain include radiation-sensitive acid generators, solvents, and high-fluorine-content polymers.

[0101] [Radiation-sensitive acid generator] A radiation-sensitive acid generator (hereinafter also simply referred to as "acid generator") is a substance that generates acid when the composition is exposed to light. The acid generator is typically a compound (hereinafter also referred to as "compound (B)") that induces the dissociation of acid-dissociable groups under the above-mentioned normal conditions, thereby generating an acid stronger than the acid generated by compound (Q) (preferably a strong acid such as sulfonic acid, imido acid, or methidoic acid) in the composition. It is preferable to blend compound (B) together with polymer (A) in the composition, so that the acid generated by compound (B) causes the acid-dissociable groups of polymer (A) to be removed, generating acid groups, thereby causing the dissolution rate of polymer (A) in the developer to differ between the exposed and unexposed areas.

[0102] The compound (B) to be included in this composition is not particularly limited, and any known radiation-sensitive acid generator used in resist pattern formation can be used. The compound (B) to be incorporated into this composition is, for example, an onium salt consisting of a radiation-sensitive onium cation and an organic anion. Among the compounds (B), the compound represented by the following formula (2) is preferred. [ka] (In formula (2), W 2is a monovalent organic group having 3 to 40 carbon atoms. L 2 is a single bond or a divalent linking group. R 7 R 8 R 9 and R 10 are, independently of one another, a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a fluorine atom or a fluoroalkyl group having 1 to 10 carbon atoms. a is an integer from 0 to 8. When a is 2 or more, a plurality of R 7 and R 8 are the same as or different from one another. However, among the (a×2 + 2) groups constituting the group consisting of R 7 R 8 R 9 and R 10 at least one is a fluorine atom or a fluoroalkyl group. X + is a monovalent cation.)

[0103] In the above formula (2), the monovalent organic group represented by W 2 having 1 to 20 carbon atoms may be linear or cyclic. When W 2 is a monovalent linear organic group, specific examples thereof include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, a linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms, a monovalent group having 1 to 20 carbon atoms in which one or more hydrogen atoms of the linear hydrocarbon group are substituted with a halogen atom, a hydroxy group, a cyano group, etc., and a monovalent group having 2 to 20 carbon atoms containing an ester group, a (thio)ether group, an amide group, etc. between the carbon-carbon bonds of the linear hydrocarbon group.

[0104] When W 2 is a monovalent cyclic organic group, the cyclic organic group may be a group having a cyclic structure having 3 to 20 carbon atoms and is not particularly limited. When W 2 is a monovalent cyclic organic group, W 2The cyclic structures that can be possessed include alicyclic hydrocarbon structures with 3 to 20 carbon atoms, aliphatic heterocyclic structures with 3 to 20 carbon atoms, and aromatic ring structures with 6 to 20 carbon atoms. These cyclic structures may have substituents. Examples of substituents include alkoxy groups, alkoxycarbonyl groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), hydroxyl groups, and cyano groups. Also, W 2 If is a monovalent cyclic organic group, W 2 It may have both a ring-like structure and a chain-like structure.

[0105] Examples of alicyclic hydrocarbon structures having 3 to 20 carbon atoms include alicyclic monocyclic structures having 3 to 20 carbon atoms and alicyclic polycyclic structures having 6 to 20 carbon atoms. The alicyclic monocyclic structures having 3 to 20 carbon atoms and the alicyclic polycyclic structures having 6 to 20 carbon atoms may be either saturated hydrocarbon structures or unsaturated hydrocarbon structures. Furthermore, the alicyclic polycyclic structures may be either bridged alicyclic hydrocarbon structures or condensed alicyclic hydrocarbon structures.

[0106] Examples of saturated hydrocarbon structures among alicyclic monocyclic structures include cyclopentane, cyclohexane, cycloheptane, and cyclooctane structures. Examples of unsaturated hydrocarbon structures include cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene structures. As for alicyclic polycyclic structures, bridged alicyclic saturated hydrocarbon structures are preferred, such as bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane, or tricyclo[3.3.1.1 3,7 It is preferable to have a decane structure.

[0107] Examples of aliphatic heterocyclic structures having 3 to 20 carbon atoms include cyclic ether structures, lactone structures, cyclic carbonate structures, sultone structures, and thioxane structures. These aliphatic heterocyclic structures may be monocyclic or polycyclic, and may also be bridged, fused, or spirocyclic structures. 2The aliphatic heterocyclic structure with 3 to 20 carbon atoms represented by may be a combination of two or more of the following: bridged structures, fused ring structures, and spiro ring structures. Examples of aromatic ring structures with 6 to 20 carbon atoms include benzene structures, naphthalene structures, anthracene structures, indene structures, and fluorene structures.

[0108] From the viewpoint of improving the transparency of the resist film obtained with this composition while increasing the hydrophobicity of the film, thereby increasing the difference in solubility in the developer between the exposed and unexposed areas, the W in formula (2) above 2 The group is preferably a monovalent cyclic organic group, more preferably having an alicyclic hydrocarbon structure or an aliphatic heterocyclic structure, and even more preferably having a bridged alicyclic saturated hydrocarbon structure or a bridged aliphatic heterocyclic structure. 2 From the viewpoint of sensitivity, it is preferable that it does not contain fluorine atoms.

[0109] L 2 The divalent linking group represented by is preferably -O-, -CO-, -COO-, -O-CO-O-, -S-, -SO2-, or -CONH-.

[0110] R 7 , R 8 , R 9 and R 10 The hydrocarbon group having 1 to 10 carbon atoms represented by is preferably an alkyl group or a cycloalkyl group, and particularly preferably an alkyl group. Of these, R 7 , R 8 , R 9 and R 10The hydrocarbon group represented is more preferably a methyl group, an ethyl group, or an isopropyl group. Examples of fluoroalkyl groups having 1 to 10 carbon atoms include trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, heptafluoro-n-propyl group, heptafluoro-i-propyl group, nonafluoro-n-butyl group, nonafluoro-i-butyl group, nonafluoro-t-butyl group, 2,2,3,3,4,4,5,5-octafluoro-n-pentyl group, tridecafluoro-n-hexyl group, 5,5,5-trifluoro-1,1-diethylpentyl group, etc. Of these, R 7 , R 8 , R 9 and R 10 The fluoroalkyl group represented by is preferably a fluoroalkyl group having 1 to 3 carbon atoms, and more preferably a trifluoromethyl group.

[0111] R in the formula 7 , R 8 , R 9 and R 10 One or more of the (a × 2 + 2) groups constituting the group consisting of are fluorine atoms or fluoroalkyl groups. For example, when a is 1, the R present in the formula 7 , R 8 , R 9 and R 10 One or more of these are a fluorine atom, a fluoroalkyl group, or a fluorine atom or a fluoroalkyl group. If a is 2, then R present in the formula 7 , R 7 , R 8 , R 8 , R 9 and R 10 One or more of these are fluorine atoms, fluoroalkyl groups, or fluorine atoms or fluoroalkyl groups. Among these, R is particularly important because it increases the acidity of the acid produced. 9 , R 10 Alternatively, it is preferable that both are a fluorine atom or a trifluoromethyl group, R 9 and R10 It is particularly preferable that both are fluorine atoms or trifluoromethyl groups. a is preferably between 0 and 5, and more preferably between 0 and 2.

[0112] A specific example of an anion possessed by compound (B) is the anion represented by the following formula. [ka] [ka] [ka]

[0113] In equation (2) above, X + X is a monovalent cation. + The monovalent cation represented by is preferably a monovalent radiosensitive onium cation, and examples include radiodegradable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Specific examples of radiodegradable onium cations containing these elements include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, and pyridinium cations. Of these, X + The sulfonium cation or iodonium cation is preferred, and specifically, the cations represented by formulas (X-1) to (X-6) above are examples.

[0114] Specific examples of compound (B) include any one of the examples of anions in compound (B) and X + Examples of monovalent cations represented by include onium salt compounds formed by combining any one of the examples provided. Compound (B) may be used alone or in combination of two or more.

[0115] In this composition, the content of the acid generator can be appropriately selected depending on the type of polymer (A) used, the exposure conditions, the required sensitivity, etc. The content of the acid generator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of polymer (A). Furthermore, the content of the acid generator is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of polymer (A). By setting the content of the acid generator within the above range, high sensitivity can be achieved during resist pattern formation, as well as good LWR performance, CDU performance, and pattern shape characteristics.

[0116] <Solvent> The solvent is not particularly limited and can be any solvent capable of dissolving or dispersing the components incorporated into this composition. Examples of solvents include alcohols, ethers, ketones, amides, esters, hydrocarbons, and the like.

[0117] Examples of alcohols include aliphatic monoalcohols with 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohols with 3 to 18 carbon atoms such as cyclohexanol; polyhydric alcohols with 2 to 18 carbon atoms such as 1,2-propylene glycol; and polyhydric alcohol partial ethers with 3 to 19 carbon atoms such as propylene glycol monomethyl ether. Examples of ethers include dialkyl ethers such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ethers such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ethers such as diphenyl ether and anisole.

[0118] Examples of ketones include linear ketones such as acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, and trimethylnonanone; cyclic ketones such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, acetophenone, and diacetone alcohol. Examples of amides include cyclic amides such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and linear amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0119] Examples of esters include monocarboxylic acid esters such as n-butyl acetate and ethyl lactate; polyhydric alcohol carboxylates such as propylene glycol acetate; polyhydric alcohol partial ether carboxylates such as propylene glycol monomethyl ether acetate; polyhydric carboxylic acid diesters such as diethyl oxalate; carbonates such as dimethyl carbonate and diethyl carbonate; and cyclic esters such as γ-butyrolactone. Examples of hydrocarbons include aliphatic hydrocarbons with 5 to 12 carbon atoms such as n-pentane and n-hexane; and aromatic hydrocarbons with 6 to 16 carbon atoms such as toluene and xylene.

[0120] The solvent preferably contains at least one selected from the group consisting of esters and ketones, more preferably at least one selected from the group consisting of polyhydric alcohol partial ether carboxylates and cyclic ketones, and even more preferably at least one of propylene glycol monomethyl ether acetate, ethyl lactate, and cyclohexanone. One or more solvents can be used.

[0121] <High fluorine content polymer> A high-fluorine-content polymer (hereinafter also referred to as "polymer (E)") is a polymer with a higher mass content of fluorine atoms than polymer (A). When this composition contains polymer (E), polymer (E) can be unevenly distributed on the surface of the resist film compared to polymer (A), thereby improving the water repellency of the surface of the resist film during immersion exposure.

[0122] The fluorine atom content of polymer (E) is not particularly limited, as long as it is greater than that of polymer (A). The fluorine atom content of polymer (E) is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 4% by mass or more, and particularly preferably 7% by mass or more. Furthermore, the fluorine atom content of polymer [E] is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The fluorine atom content (mass%) of the polymer is: 13 The polymer structure can be determined by measuring the ¹³C NMR spectrum, and the calculation can be derived from that structure.

[0123] Examples of structural units containing fluorine atoms (hereinafter also referred to as "structural units (F)") of polymer (E) include structural units (fa) and structural units (fb) shown below. Polymer (E) may have either structural unit (fa) or structural unit (fb) as structural unit (F), or it may have both structural unit (fa) and structural unit (fb).

[0124] [Structural Unit (fa)] The structural unit (fa) is a structural unit represented by the following formula (8-1). The polymer (E) can have its fluorine atom content adjusted by having structural unit (fa). [ka] (In formula (8-1), R CG is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2-O-NH-, -CONH-, or -O-CO-NH-. R E This refers to a monovalent fluorinated linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0125] In the above equation (8-1), R C From the viewpoint of copolymerization of the monomer that gives the structural unit (fa), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred. Also, from the viewpoint of copolymerization of the monomer that gives the structural unit (fa), single bonds or -COO- are preferred, and -COO- is more preferred.

[0126] R E Examples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by R, 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. E Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by R, include monocyclic or polycyclic alicyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms are substituted with fluorine atoms. Among these, R E The group is preferably a monovalent fluorinated linear hydrocarbon group, more preferably a monovalent fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, or a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0127] When the polymer (E) has structural units (fa), the content of structural units (fa) is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, relative to the total structural units constituting the polymer (E). Furthermore, the content of structural units (fa) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, relative to the total structural units constituting the polymer (E). By setting the content of structural units (fa) within the above range, the mass content of fluorine atoms in the polymer (E) can be adjusted more appropriately, further promoting the uneven distribution to the surface layer of the resist film, thereby further improving the water repellency of the resist film during immersion exposure.

[0128] [Structural Unit (fb)] The structural unit (fb) is represented by the following formula (8-2). The polymer (E) has improved solubility in alkaline developer due to the presence of the structural unit (fb), thereby further suppressing the occurrence of development defects. [ka] (In formula (8-2), R F R is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. 59 is a (s+1) valent hydrocarbon group having 1 to 20 carbon atoms, or the R of said hydrocarbon group. 60 It is a group to which an oxygen atom, sulfur atom, -NR'-, carbonyl group, -CO-O-, or -CO-NH- is bonded at one end. R' is a hydrogen atom or a monovalent organic group. 60 X is a single bond or a divalent organic group having 1 to 20 carbon atoms. 12 This is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. 11 R'' is an oxygen atom, -NR''-, -CO-O-*, or -SO2-O-*. R'' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" is R 61 This shows the binding site. 61R is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. s is an integer from 1 to 3. However, if s is 2 or 3, multiple R groups are formed. 60 , X 12 , A 11 and R 61 (These are either the same or different.)

[0129] Structural units (fb) can be divided into those that have alkali-soluble groups and those that have groups that dissociate under the action of alkali, increasing their solubility in alkaline developers (hereinafter also simply referred to as "alkali-dissociable groups").

[0130] If the structural unit (fb) has an alkali-soluble group, R 61 is a hydrogen atom, A 11 is an oxygen atom, -COO-* or -SO2O-*. "*" represents R 61 This indicates the site of binding. X 12 This is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 11 If X is an oxygen atom, 12 is, A 11 It is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which it is bonded. 60 is a single bond or a divalent organic group with 1 to 20 carbon atoms. If s is 2 or 3, there are multiple R 60 , X 12 , A 11 and R 61 These are either identical or different from each other. The structural unit (fb) having an alkali-soluble group increases its affinity for alkaline developers and suppresses development defects.

[0131] If the structural unit (fb) has an alkali-dissociable group, R 61 A is a monovalent organic group having 1 to 30 carbon atoms. 11 is an oxygen atom, -NR''-, -COO-*, or -SO2O-*. "*" represents R 61 This indicates the site of binding. X 12 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 60A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 11 If X is -COO-* or -SO2O-*, 12 or R 61 is, A 11 It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. 11 If X is an oxygen atom, 12 or R 60 It is a single bond, R 59 R is a hydrocarbon group with 1 to 20 carbon atoms. 60 It is a structure in which a carbonyl group is bonded to the terminal end, R 61 is an organic group containing a fluorine atom. When s is 2 or 3, multiple R 60 , X 12 , A 11 and R 61 These are either identical or different from each other. The presence of alkali-dissociable groups in the structural units (fb) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. This increases the affinity for the developer, allowing for more efficient suppression of development defects. Examples of structural units (fb) with alkali-dissociable groups include A 11 is -COO-*, and R 61 Or X 12 Alternatively, it is particularly preferable that both of these have fluorine atoms.

[0132] When the polymer (E) has structural units (fb), the content of structural units (fb) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, relative to the total structural units constituting the polymer (E). Furthermore, the content of structural units (fb) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, relative to the total structural units constituting the polymer (E). By setting the content of structural units (fb) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0133] In addition to structural units (fa) and (fb), polymer (E) may also contain structural units (I) having acid-dissociable groups and structural units having an alicyclic hydrocarbon structure represented by the following formula (9) (hereinafter also referred to as "structural unit (G)"). [ka] (In the above formula (9), R G1 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. G2 (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0134] In equation (9) above, R G2 As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (3), R 13 ~R 15 Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms can be given.

[0135] When polymer (E) contains structural units represented by formula (9) above, the content of such structural units 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 polymer (E). Furthermore, the content of structural units represented by formula (9) above is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, relative to the total structural units constituting polymer (E).

[0136] The Mw of polymer (E) determined by GPC is preferably 1,000 or more, more preferably 3,000 or more, and even more preferably 4,000 or more. Furthermore, the Mw of polymer (E) is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 20,000 or less. The molecular weight distribution (Mw / Mn), expressed as the ratio of Mn to Mw determined by GPC of polymer (E), is preferably 1 or more and 5 or less, and more preferably 1 or more and 3 or less.

[0137] If the composition contains polymer (E), the content of polymer (E) in the composition is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of polymer (A). Furthermore, the content of polymer (E) is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of polymer (A). Note that the composition may contain polymer (E) alone or in combination of two or more types.

[0138] <Other optional ingredients> This composition may further contain components other than the polymer (A), compound (Q), compound (B), solvent, and polymer (E) described above (hereinafter also referred to as "other optional components"). Other optional components include acid diffusion control agents other than compound (Q) (for example, "N(R) N1 )(R N2 )(R N3 )" represents nitrogen-containing compounds (however, R N1 , R N2 and R N3 Examples of other optional components in this composition include a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, a photo-disintegrating base different from the compound represented by formula (1) above, a surfactant, an alicyclic skeleton-containing compound (e.g., 1-adamantanecarboxylic acid, 2-adamantanone, t-butyl deoxycholate, etc.), a sensitizer, a localization accelerator, etc. The proportion of other optional components in this composition can be appropriately selected according to each component, as long as it does not impair the effects of this disclosure.

[0139] Furthermore, when an acid diffusion control agent other than compound (Q) is incorporated into this composition, from the viewpoint of obtaining a radiation-sensitive composition that exhibits good sensitivity while also having excellent CDU performance and pattern rectangularity, the content of the acid diffusion control agent other than compound (Q) is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less, relative to the total amount of acid diffusion control agents contained in this composition.

[0140] <Method for producing a radiation-sensitive composition> This composition can be produced, for example, by mixing polymer (A) and compound (Q), as well as other components such as solvents as needed, in desired proportions, and filtering the resulting mixture, preferably using a filter (for example, a filter with a pore size of about 0.2 μm). The solid content concentration of this composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. Furthermore, the solid content concentration of this composition is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less. By setting the solid content concentration of this composition within the above range, good coatability and good resist pattern shape can be achieved.

[0141] The resulting composition can be used as a positive-type pattern-forming composition for forming patterns using an alkaline developer, or as a negative-type pattern-forming composition for forming patterns using a developer containing an organic solvent. Of these, the composition is particularly suitable as a negative-type pattern-forming composition for use with an organic solvent developer because it exhibits high sensitivity while exhibiting a superior effect in developing the exposed resist film into a rectangular pattern.

[0142] ≪Method for forming a resist pattern≫ The resist pattern formation method in this disclosure includes the steps of coating one side of a substrate with the composition (hereinafter also referred to as the "coating step"), exposing the resist film obtained in the coating step (hereinafter also referred to as the "exposure step"), and developing the exposed resist film (hereinafter also referred to as the "development step"). Examples of patterns formed by the resist pattern formation method in this disclosure include line-and-space patterns and hole patterns. Since the resist film is formed using the composition in the resist pattern formation method in this disclosure, it is possible to form a resist pattern with good sensitivity and lithography characteristics and few development defects. Each step will be described below.

[0143] [Coating Process] In the coating process, a resist film is formed on the substrate by coating one side of the substrate with the composition. Conventional known substrates can be used as the substrate on which the resist film is formed, 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 and used. Examples of coating methods for the composition include rotary coating (spin coating), casting coating, and roll coating. After coating, pre-baking (PB) may be performed to volatilize the solvent in the coating film. The temperature of PB is preferably 60°C or higher, more preferably 80°C or higher. Furthermore, the temperature of PB is preferably 140°C or lower, more preferably 120°C or lower. The PB time is preferably 5 seconds or more, more preferably 10 seconds or more. Furthermore, the PB time is preferably 600 seconds or less, more preferably 300 seconds or less. The average thickness of the formed resist film is preferably 10 to 1,000 nm, and more preferably 20 to 500 nm.

[0144] When immersion lithography is performed in the next exposure step, regardless of the presence or absence of water-repellent polymer additives such as polymer (E) in this composition, an immersion-insoluble protective film may be further provided on the resist film formed by this composition to avoid direct contact between the immersion liquid and the resist film. As the immersion-protective film, either a solvent-peelable protective film that is peeled off with a solvent before the development step (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 step (see, for example, International Publication Nos. 2005 / 069076 and International Publication Nos. 2006 / 035790) may be used. From the viewpoint of throughput, it is preferable to use a developer-peelable immersion-protective film.

[0145] [Synthesis process] In the exposure process, the resist film obtained by the coating process described above is exposed. This exposure is performed by irradiating the resist film with radiation through a photomask, and possibly through an immersion medium such as water. The radiation can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), 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. Of these, the radiation irradiated onto the resist film formed using this composition is preferably far ultraviolet light, EUV, or an electron beam, more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, or an electron beam, and even more preferably ArF excimer laser light, EUV, or an electron beam.

[0146] 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 exposed areas of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB can increase the difference in solubility in the developer between the exposed and unexposed areas. The PEB temperature is preferably 50°C or higher, more preferably 80°C or higher. Furthermore, the PEB temperature is preferably 180°C or lower, more preferably 130°C or lower. The PEB duration is preferably 5 seconds or more, more preferably 10 seconds or more. Furthermore, the PEB duration is preferably 600 seconds or less, more preferably 300 seconds or less.

[0147] [Development process] In the development process, the exposed resist film is developed with a developer. This allows for the formation of the desired resist pattern. The developer may be an alkaline developer or an organic solvent developer. The developer can be appropriately selected depending on the desired pattern (positive pattern or negative pattern).

[0148] Examples of developers used in alkaline development include aqueous alkaline solutions containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred.

[0149] Examples of developers used in organic solvent development include organic solvents such as hydrocarbons, ethers, esters, ketones, and alcohols, or solvents containing such organic solvents. Examples of organic solvents include one or more of the solvents listed as solvents that may be incorporated into this composition. Among these, ethers, esters, and ketones are preferred. Among ethers, glycol ethers are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. Among esters, acetate esters are preferred, and n-butyl acetate and amyl acetate are more preferred. Among ketones, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than organic solvents in the developer include water and silicone oil.

[0150] Development methods include, for example, immersing the substrate in a tank filled with developer for a certain period of time (dip method), developing by puddling the developer onto the substrate surface using surface tension and leaving it still for a certain period of time (paddle method), spraying the developer onto the substrate surface (spray method), and continuously dispensing the developer at a constant speed while scanning a developer nozzle on a substrate rotating at a constant speed (dynamic dispensing method). After development, it is common to wash with a rinsing solution such as water or alcohol and then dry the substrate.

[0151] The composition described above, by containing compound (Q) together with polymer (A), exhibits high sensitivity during resist pattern formation and has excellent LWR and CDU performance. Furthermore, this composition allows for good pattern shape of the resist pattern. Therefore, this composition can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

[0152] Based on the details of this disclosure described above, the following means are provided. [Method 1] A radiation-sensitive composition comprising a polymer having an acid-dissociable group and a compound represented by the above formula (1). [Method 2] R in formula (1) above 1 The radiation-sensitive composition according to [Method 1], wherein the group is represented by the above formula (r-1). [Method 3] W in the above formula (r-1) 1 The radiation-sensitive composition according to [Method 2], wherein is a group represented by the above formula (w1-1) or formula (w1-2). [Method 4] A radiation-sensitive composition according to any one of [Method 1] to [Method 3], further comprising the compound represented by formula (2) above. [Method 5] The polymer is a radiation-sensitive composition according to any one of [Method 1] to [Method 4], wherein the polymer has a structural unit represented by the above formula (3). [Method 6] A pattern forming method comprising the steps of: applying a radiation-sensitive composition described in any of [Method 1] to [Method 5] onto a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film. [Method 7] The pattern forming method according to [Method 6], wherein the developing step is a step of developing the exposed resist film with an alkaline developer. [Method 8] A photodecayable base represented by the above formula (1). [Examples]

[0153] The present disclosure will be described below in detail based on examples, but the present disclosure is not limited to these examples. In the following examples, "parts" and "%" refer to mass unless otherwise specified. The methods for measuring various physical properties are shown below.

[0154] [Weight-average molecular weight (Mw), number-average molecular weight (Mn), and degree of dispersion (Mw / Mn)] The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using monodisperse polystyrene as the standard, with Tosoh Corporation GPC columns (G2000HXL: 2 columns, G3000HXL: 1 column, G4000HXL: 1 column) under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 mass%, sample injection volume: 100 μL, column temperature: 40°C, and detector: differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measured results of Mw and Mn.

[0155] [ 13 C-NMR analysis] polymer 13 ¹

[0156] The following are the resins used in the preparation of the radiation-sensitive resin compositions in each example: [A] resin, [B] radiation-sensitive acid generator, [C] acid diffusion control agent, [D] solvent, and [E] high-fluorine content resin.

[0157] <[A] Resins and [E] High-fluorine content resins> • Synthesis of [A] resin and [E] high-fluorine content resin The monomers used in the synthesis of each resin and the high-fluorine-content resin are shown below. In the following synthesis examples, unless otherwise specified, "parts by mass" refers to the value when the total mass of the monomers used is set to 100 parts by mass, and "mol%" refers to the value when the total number of moles of the monomers used is set to 100 mol%.

[0158] [ka] [ka]

[0159] [Synthesis Example 1] (Synthesis of resin (A-1)) Monomers (M-1), (M-2), (M-10), (M-13), and (M-14) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 30 / 15 / 30 / 15 / 10 (mol%). AIBN (azobisisobutyronitrile) (3 mol% of the total monomers used, 100 mol%) was added as an initiator to prepare the monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C. The monomer solution was then added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdered resin (A-1) (yield: 83%). The Mw of resin (A-1) was 8,800, and the Mw / Mn ratio was 1.50. 13 13C-NMR analysis revealed that the content percentages of each structural unit derived from monomer (M-1), monomer (M-2), monomer (M-10), monomer (M-13), and monomer (M-14) were 31.3 mol%, 13.8 mol%, 29.1 mol%, 15.2 mol%, and 10.6 mol%, respectively.

[0160] [Synthesis Examples 2-11] (Synthesis of resins (A-2) to (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the monomers used were of the types and proportions shown in Table 1 below. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained resins are also shown in Table 1 below. Note that "-" in Table 1 below indicates that the corresponding monomer was not used (the same applies to subsequent tables).

[0161] [Table 1]

[0162] [Synthesis Example 12] (Synthesis of resin (A-12)) Monomer (M-1) and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to a molar ratio of 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 1-methoxy-2-propanol was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the obtained solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the resin. The obtained solid was filtered off and dried at 50°C for 13 hours to obtain a white powdered resin (A-12) (yield: 79%). The Mw of resin (A-12) was 5,200, and the Mw / Mn ratio was 1.60. 1313C-NMR analysis revealed that the content of each structural unit derived from monomer (M-1) and monomer (M-18) was 51.3 mol% and 48.7 mol%, respectively.

[0163] [Synthesis Examples 13-21] (Synthesis of resin (A-13) to resin (A-21)) Resins (A-13) to (A-21) were synthesized in the same manner as in Synthesis Example 12, except that the monomers used were of the types and proportions shown in Table 2 below. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained resins are also shown in Table 2 below.

[0164] [Table 2]

[0165] [Synthesis Example 22] (Synthesis of high-fluorine content resin (E-1)) Monomers (M-1), (M-15), (M-16), and (M-20) were dissolved in 200 parts by mass of 2-butanone to a molar ratio of 20 / 10 / 10 / 60 (mol%), and AIBN (4 mol%) was added as an initiator to prepare monomer solutions. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solutions were added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. A solution of the high-fluorine-content resin (E-1) was obtained by substituting the solvent with propylene glycol monomethyl ether acetate (yield: 69%). The Mw of the high-fluorine-content resin (E-1) was 6,000, and the Mw / Mn ratio was 1.62. 1313C-NMR analysis revealed that the content percentages of each structural unit derived from monomer (M-1), monomer (M-15), monomer (M-16), and monomer (M-20) were 19.9 mol%, 10.3 mol%, 9.7 mol%, and 60.1 mol%, respectively.

[0166] [Synthesis Examples 23-27] (Synthesis of high-fluorine content resins (E-2) to high-fluorine content resins (E-6)) High-fluorine-content resins (E-2) to (E-6) were synthesized in the same manner as in Synthesis Example 22, except that monomers of the types and proportions shown in Table 3 below were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained high-fluorine-content resins are shown in accordance with Table 3 below.

[0167] [Table 3]

[0168] <[B] Radiation-sensitive acid generator> B-1 to B-14: Compounds represented by the following formulas (B-1) to (B-14) (Hereafter, the compounds represented by formulas (B-1) to (B-14) may be referred to as "compound (B-1)" to "compound (B-14)," respectively.) [ka] [ka]

[0169] <[C] Acid diffusion control agent> • Synthesis of [C] acid diffusion control agents [Synthesis Example 28] (Synthesis of compound (C-1)) Compound (C-1) was synthesized according to the following synthesis scheme. [ka]

[0170] 20.0 mmol of methyl 2,5-dihydroxybenzoate, 20.0 mmol of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane, 25.0 mmol of potassium carbonate, and 40 g of dimethylformamide were added to a reaction vessel and stirred at 120°C for 12 hours. Then, saturated aqueous ammonium chloride solution was added to the reaction solution to terminate the reaction, and ethyl acetate was added for extraction, separating the organic layer. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the alkylated product was obtained in good yield by recrystallization.

[0171] To the alkylated product described above, 20.0 mmol of sodium hydroxide and 20.0 mmol of triphenylsulfonium bromide were added, and a mixture of water and dichloromethane (1:3 by mass ratio) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the compound represented by formula (C-1) above (referred to as "compound (C-1)") was obtained in good yield.

[0172] [Synthesis Examples 29-41] (Synthesis of compounds (C-2) to (C-14)) Except for appropriately changing the raw materials and precursors, the onium salts represented by the following formulas (C-2) to (C-14) (hereinafter, the compounds represented by formulas (C-2) to (C-14) may be referred to as "compound (C-2)" to "compound (C-14)" respectively) were synthesized in the same manner as in Synthesis Example 28.

[0173] [ka] [ka]

[0174] [Synthesis Example 42] (Synthesis of compound (C-15)) Compound (C-15) was synthesized according to the following synthesis scheme. [ka]

[0175] 20.0 mmol of methyl 5-formylbenzoate, 20.0 mmol of ethylene glycol, 5.0 mmol of pyridinium p-toluenesulfonate, and 40 g of toluene were added to a reaction vessel and stirred at room temperature for 3 hours. Then, saturated aqueous sodium bicarbonate solution was added to the reaction solution to terminate the reaction, and ethyl acetate was added for extraction, separating the organic layer. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the acetal was obtained in good yield by recrystallization.

[0176] To the above acetal compound, 20.0 mmol of sodium hydroxide and 20.0 mmol of triphenylsulfonium bromide were added, and a mixture of water and dichloromethane (1:3 by mass ratio) was added to prepare a 0.5 M solution. After vigorous stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the compound represented by the above formula (C-15) (referred to as "compound (C-15)") was obtained in good yield.

[0177] [Synthesis Examples 43-52] (Synthesis of compounds (C-16) to (C-25)) Except for appropriately changing the raw materials and precursors, the onium salts represented by the following formulas (C-16) to (C-25) (hereinafter, the compounds represented by formulas (C-16) to (C-25) may be referred to as "compound (C-16)" to "compound (C-25)" respectively) were synthesized in the same manner as in Synthesis Example 42. [ka]

[0178] • Onium salts other than compounds (C-1) to (C-25) cc-1 to cc-9: Compounds represented by the following formulas (cc-1) to (cc-9) (hereinafter, the compounds represented by formulas (cc-1) to (cc-9) may be described as "Compound (cc-1)" to "Compound (cc-9)", respectively).

Chemical formula

[0179] <[D] Solvent> D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol monomethyl ether D-3: γ-Butyrolactone D-4: Ethyl lactate

[0180] <Preparation of positive radiation-sensitive resin composition for ArF exposure> [Example 1] [A] 100 parts by mass of (A-1) as a resin, [B] 10.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [C] 5.0 parts by mass of (C-1) as an acid diffusion controller, [E] 3.0 parts by mass (solid content) of (E-1) as a high fluorine content resin, and 3,230 parts by mass (2,240 / 960 / 30 (parts by mass)) of a mixed solvent of (D-1) / (D-2) / (D-3) as [D] solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-1).

[0181] [Examples 2 to 55 and Comparative Examples 1 to 9] Except for using the components of the types and contents shown in Tables 4 and 5 below, radiation-sensitive resin compositions (J-2) to (J-55) and (CJ-1) to (CJ-9) were prepared in the same manner as in Example 1, respectively.

[0182]

Table 4

[0183]

Table 5

[0184] <Formation of a resist pattern using a positive radiation-sensitive resin composition for ArF exposure> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), a composition for forming a lower layer film ("ARC66" manufactured by Brewer Science, Inc.) was applied, and then heated at 205°C for 60 seconds to form a lower layer film with an average thickness of 100 nm. Using the above spin coater, the prepared positive radiation-sensitive resin composition for ArF exposure was applied onto this lower layer film, and PB (pre-baking) was performed at 90°C for 60 seconds. Thereafter, by cooling at 23°C for 30 seconds, a resist film with an average thickness of 90 nm was formed. Next, with respect to this resist film, using an ArF excimer laser immersion exposure apparatus ("TWINSCAN XT-1900i" manufactured by ASML), under optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6), exposure was performed through a mask pattern with a 40 nm space and a 105 nm pitch. After exposure, PEB (post-exposure baking) was performed at 90°C for 60 seconds. Thereafter, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive resist pattern (40 nm line and space pattern).

[0185] <Evaluation> Regarding the resist pattern formed using the above positive radiation-sensitive resin composition for ArF exposure, sensitivity, LWR performance, and pattern rectangularity were evaluated according to the following methods. The results are shown in Tables 6 and 7 below. For measuring the length of the resist pattern, a scanning electron microscope ("CG-5000" manufactured by Hitachi High-Technologies Corporation) was used.

[0186] [Sensitivity] In the formation of a resist pattern using the above positive radiation-sensitive resin composition for ArF exposure, the exposure dose for forming a 40 nm hole pattern was taken as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm 2 )². The sensitivity was 30 mJ / cm²2 The following cases are considered "good" and 30 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0187] [LWR performance] The mask size was adjusted to form a 40nm line-and-space pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation described above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates lower line roughness (rattling) and better performance. LWR performance was evaluated as "good" if it was 3.0nm or less, and "poor" if it was greater than 3.0nm.

[0188] [Pattern Rectangle] The 40nm line-and-space resist patterns formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above were observed using the scanning electron microscope described above, and the cross-sectional shape of the line-and-space patterns was evaluated. The rectangularity of the resist patterns was evaluated as follows: if the ratio of the length of the upper side to the length of the lower side in the cross-sectional shape was 1.00 or more and 1.05 or less, it was rated as "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was rated as "B" (good); and if it was greater than 1.10, it was rated as "C" (poor).

[0189] [Table 6]

[0190] [Table 7]

[0191] As is clear from the results in Tables 6 and 7, the radiation-sensitive resin compositions of Examples 1 to 55 had good sensitivity, LWR performance, and pattern rectangularity when used for ArF exposure. In contrast, the radiation-sensitive resin compositions of Comparative Examples 1 to 9 were inferior in sensitivity, LWR performance, and pattern rectangularity compared to Examples 1 to 55. Therefore, when the radiation-sensitive resin compositions of Examples 1 to 55 were used for positive-tone ArF exposure, it can be said that high sensitivity and good LWR performance were exhibited, and a resist pattern with excellent rectangularity could be formed.

[0192] <Preparation of Positive-Type Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure> [Example 56] [A] 100 parts by mass of (A-12) as the resin, [B] 40.0 parts by mass of (B-12) as the radiation-sensitive acid generator, [C] 24.0 parts by mass of (C-1) as the acid diffusion controller, [E] 3.0 parts by mass (solid content) of (E-5) as the high-fluorine content resin, and [D] 6,110 parts by mass of the mixed solvent of (D-1) / (D-2) (1,830 / 4,280 (parts by mass)) as the solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-56).

[0193] [Examples 57 to 84 and Comparative Examples 10 to 13] Except for using the components of the types and contents shown in Table 8 below, the radiation-sensitive resin compositions (J-57) to (J-84) and (CJ-10) to (CJ-13) were prepared in the same manner as in Example 56, respectively.

[0194]

Table 8

[0195] <Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Resin Composition for EUV Exposure> A base layer film with an average thickness of 105 nm was formed on a 12-inch silicon wafer by applying a base layer film formation composition (Brewer Science's "ARC66") using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12") and then heating at 205°C for 60 seconds. The prepared positive-type radiation-sensitive resin composition for EUV lithography was applied to this base layer using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV lithography apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline-developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (32 nm line and space pattern).

[0196] <Rating> The sensitivity, LWR performance, and pattern rectangularity of resist patterns formed using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure were evaluated according to the following method. The results are shown in Table 9 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0197] [sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure, the exposure amount for forming a 32nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 25 mJ / cm². 2 The following cases are considered "good" and 25 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0198] [LWR performance] The mask size was adjusted to form a resist pattern by irradiating the optimum exposure amount obtained in the above sensitivity evaluation so as to form a 32 nm line and space pattern. The formed resist pattern was observed from the top of the pattern using the above scanning electron microscope. The variation in line width was measured at 500 points in total, the 3-sigma value was obtained from the distribution of the measured values, and this 3-sigma value was defined as LWR (nm). The LWR performance indicates that the smaller the value, the smaller the roughness of the line and the better it is. The LWR performance was evaluated as "good" when it was 3.0 nm or less and "bad" when it exceeded 3.0 nm.

[0199] [Pattern Rectangularity] Regarding the resist pattern of 40 nm line and space formed by irradiating the optimum exposure amount obtained in the above sensitivity evaluation, it was observed using the above scanning electron microscope, and the cross-sectional shape of the line and space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" (extremely good) if the ratio of the length of the upper side to the length of the lower side in the cross-sectional shape was 1.00 or more and 1.05 or less, "B" (good) if it exceeded 1.05 and was 1.10 or less, and "C" (bad) if it exceeded 1.10.

[0200]

Table 9

[0201] As is clear from the results in Table 9, the radiation-sensitive resin compositions of Examples 56 to 84 had good sensitivity, LWR performance, and pattern rectangularity when used for EUV exposure. On the other hand, the radiation-sensitive resin compositions of Comparative Examples 10 to 13 were inferior in sensitivity, LWR performance, and pattern rectangularity compared to Examples 56 to 84.

[0202] [Preparation of Negative-Type Radiation-Sensitive Resin Composition for ArF Exposure, and Formation and Evaluation of Resist Pattern Using this Composition> [Example 85] 100 parts by mass of (A-6) as a resin, 10.0 parts by mass of (B-2) as a radiation-sensitive acid generator, 8.0 parts by mass of (C-1) as an acid diffusion controller, 5.0 parts by mass (solid content) of (E-2) as a high-fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) (2,240 / 960 / 30 (parts by mass)) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-85).

[0203] [Examples 86 to 97 and Comparative Examples 14 to 17] Radiation-sensitive resin compositions (J-86) to (J-97) and (CJ-14) to (CJ-17) were prepared in the same manner as in Example 85, except that the components of the types and contents shown in Table 10 below were used.

[0204]

Table 10

[0205] <Formation of a resist pattern using a negative-type radiation-sensitive resin composition for ArF exposure> A base layer film with an average thickness of 100 nm was formed on a 12-inch silicon wafer by applying a base layer film formation composition (Brewer Science's "ARC66") using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12") and then heating at 205°C for 60 seconds. The ArF exposure negative-type radiation-sensitive resin composition prepared above was applied to this base layer using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA=1.35 and Dipole (σ=0.9 / 0.7) through a mask pattern with 40 nm holes and a 105 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (40 nm holes, 105 nm pitch).

[0206] <Rating> The sensitivity, CDU performance, and pattern circularity of resist patterns formed using the above-mentioned ArF exposure negative-type radiation-sensitive resin composition were evaluated according to the following method. The results are shown in Table 11 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0207] [sensitivity] In forming a resist pattern using the above ArF exposure negative radiation-sensitive resin composition, the exposure amount for forming a 40 nm hole pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 30 mJ / cm². 2 The following cases are considered "good" and 30 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0208] [CDU performance] The optimal exposure dose obtained in the above sensitivity evaluation was irradiated to form a hole pattern with 40 nm holes and a 105 nm pitch. The formed resist pattern was measured 1,800 times at arbitrary points from the top of the pattern using the above scanning electron microscope. The variation (3σ) in dimensions was determined and taken as the CDU performance (nm). The CDU performance indicates that the smaller the value, the smaller the variation in hole diameter in the long period and the better the performance. The CDU performance was evaluated as "good" when it was 2.0 nm or less and "bad" when it exceeded 2.0 nm.

[0209] [Pattern circularity] Regarding the hole pattern with 40 nm holes and a 105 nm pitch formed by irradiating the optimal exposure dose obtained in the above sensitivity evaluation, it was observed using the above scanning electron microscope, the vertical size and the horizontal size were measured respectively, and if the ratio of the vertical size / horizontal size (aspect ratio) was 0.95 or more and less than 1.05, it was evaluated as "A" (extremely good), if it was 0.90 or more and less than 0.95, or 1.05 or more and less than 1.10, it was evaluated as "B" (good), and if it was less than 0.90 or more than 1.10, it was evaluated as "C" (bad).

[0210] [Table 11]

[0211] As is clear from the results in Table 11, the radiation-sensitive resin compositions of Examples 85 to 97 had good sensitivity, CDU performance, and pattern circularity when used for ArF exposure. On the other hand, the radiation-sensitive resin compositions of Comparative Examples 14 to 17 were inferior in sensitivity, CDU performance, and pattern circularity compared to Examples 85 to 97.

[0212] <Preparation of a negative-type radiation-sensitive resin composition for EUV exposure, and formation and evaluation of a resist pattern using this composition> [Example 98] A negative-type radiation-sensitive resin composition for EUV exposure (J-98) was prepared by mixing [A] 100 parts by mass of (A-13) as a resin, [B] 30.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [C] 20.0 parts by mass of (C-9) as an acid diffusion control agent, [E] 1.0 part by mass (solids) of (E-5) as a high-fluorine-content resin, and [D] 6,110 parts by mass (4,280 / 1,830 (parts by mass)) of a mixed solvent of (D-1) / (D-4) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0213] A base layer film with an average thickness of 105 nm was formed on a 12-inch silicon wafer by applying a base layer film formation composition (Brewer Science's "ARC66") using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12") and then heating at 205°C for 60 seconds. The prepared negative-type radiation-sensitive resin composition for EUV lithography (J-98) was applied to this base layer using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV lithography apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (30 nm holes, 60 nm pitch).

[0214] The sensitivity, CDU performance, and pattern circularity of the resist pattern using the above-mentioned negative-type radiation-sensitive resin composition for EUV exposure were evaluated in the same manner as the evaluation of the resist pattern using the above-mentioned negative-type radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 98 showed good sensitivity, CDU performance, and pattern circularity even when a negative-type resist pattern was formed by EUV exposure.

[0215] The radiation-sensitive resin composition and resist pattern formation method described above exhibit good sensitivity to exposure light and excellent LWR and CDU performance. Furthermore, the resulting resist pattern has a good shape. Therefore, these can be suitably used in semiconductor device processing processes, where further miniaturization is expected.

Claims

1. A polymer having an acid-dissociable group, A photodecayable base, which is at least one selected from the group consisting of a compound represented by the following formula (1) and a compound consisting of an anion represented by the following formula (r-2) and a monovalent organic cation, A radiation-sensitive acid generator that generates an acid stronger than the photodecayable base upon exposure, A radiation-sensitive composition containing the following: 【Chemistry 1】 (In formula (1), A １ is an (m + n + 2)-valent aromatic ring group. In formula (1), "-OH" and "-COO － " are bonded to the same benzene ring in A １ , and the atom to which "-OH" is bonded and the atom to which "-COO － " is bonded are adjacent. R １ is a monovalent group having a cyclic (thio) acetal structure. m is an integer of 1 or more. When m is 2 or more, a plurality of R １ are the same as or different from each other. n is an integer of 0 or more. When n is 1, R ２ is a halogen atom or a substituted or unsubstituted monovalent hydrocarbon group. When n is 2 or more, a plurality of R ２ are independently a halogen atom, a monovalent hydrocarbon group or a substituted monovalent hydrocarbon group, or two of a plurality of R ２ are combined with each other and represent an alicyclic hydrocarbon structure or an aliphatic heterocyclic structure formed together with the atoms to which they are bonded. M ＋ is a monovalent organic cation.) 【Chemistry 9】 (In formula (r-2), Y1 and Y2 are independently oxygen atoms or sulfur atoms. R3 and R4 are independently hydrogen atoms, halogen atoms, or monovalent organic groups, or R3 and R4 together represent an alicyclic hydrocarbon structure formed with the carbon atoms to which they are bonded. A2 is a tetravalent aromatic ring group. In formula (r-2), "-OH" and "-COO-" are bonded to the same benzene ring in A2, and the atom to which "-OH" is bonded and the atom to which "-COO-" is bonded are adjacent. R5e, R5f, R6e, and R6f are independently hydrogen atoms, halogen atoms, or monovalent organic groups. t4 and t5 are 0.)

2. The aforementioned R １ The radiation-sensitive composition according to claim 1, wherein is a group represented by the following formula (r-1). 【Chemistry 2】 (In formula (r-1), X １ L is a single bond, an ether group, a thioether group, an ester group, a thioester group, or an amide group. １ This is a single bond or a substituted or unsubstituted divalent hydrocarbon group. １ This is a group obtained by removing one hydrogen atom from the structure represented by the following formula (w-1). (* represents a bond.) 【Transformation 3】 (In formula (w-1), Y １ and Y ２ These are, independently of each other, either an oxygen atom or a sulfur atom. ３ and R ４ These are, independently of each other, a hydrogen atom, a halogen atom, or a monovalent organic group, or R ３ and R ４ R represents an alicyclic hydrocarbon structure formed by combining these atoms with the carbon atoms to which they are bonded. ５ and R ６ Each of these is either a hydrogen atom, a halogen atom, or a monovalent organic group, or one of the r R atoms present in the formula. ５ and r R ６ This represents a ring structure formed when any two of these atoms are combined with the carbon atoms they bond to. r is an integer between 2 and 8. Multiple Rs are shown. ５ They are the same or different, multiple R ６ They are either the same or different.

3. The aforementioned W １ The radiation-sensitive composition according to claim 2, wherein is a group represented by the following formula (w1-1) or formula (w1-2). 【Chemistry 4】 (In formula (w1-1), Y １ , Y ２ , R ３ , R ４ And r are synonymous with equation (w-1). There are r R in the equation. ５ｘ and r R ６ｘ It satisfies either (i) or (ii) below. (i) r R ５ｘ and r R ６ｘ One of them is L １ This represents a bond between two atoms, and the remaining atoms are independently hydrogen atoms, halogen atoms, or monovalent organic groups. (ii) r R ５ｘ and r R ６ｘ Any two of these can be combined to form a ring structure with the carbon atoms to which they are bonded, and the ring structure is L １ It has a bonding relationship with r R ５ｘ and r R ６ｘ The remaining atoms are, independently of each other, hydrogen atoms, halogen atoms, or monovalent organic groups. 【Transformation 5】 (In formula (w1-2), Y １ , Y ２ , R ４ , R ５ , R ６ And r are equivalent to equation (w-1). "*" represents L １ (This represents a combination of two elements.)

4. The radiation-sensitive composition according to claim 1, comprising a compound represented by the following formula (2) as the radiation-sensitive acid generator. 【Transformation 6】 (In formula (2), W ２ L is a monovalent organic group with 3 to 40 carbon atoms. ２ R is a single bond or a divalent linking group. ７ , R ８ , R ９ and R １０ R are, independently of each other, a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a fluorine atom, or a fluoroalkyl group having 1 to 10 carbon atoms. a is an integer from 0 to 8. If a is 2 or more, there are multiple R ７ and R ８ They are either the same or different from each other. However, R in the formula ７ , R ８ , R ９ and R １０ One or more of the (a × 2 + 2) groups constituting the group consisting of the above are fluorine atoms or fluoroalkyl groups. ＋ (This is a monovalent cation.)

5. The radiation-sensitive composition according to claim 1, wherein the polymer has a structural unit represented by the following formula (3). 【Transformation 7】 (In formula (3), R １１ This is a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or an alkoxyalkyl group. Q １ R is a single bond or a substituted or unsubstituted divalent hydrocarbon group. １２ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １３ and R １４ These are, independently of each other, a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R １３ and R １４ They are combined with each other R １３ and R １４ (This represents a divalent alicyclic hydrocarbon group with 3 to 20 carbon atoms, which is formed together with the carbon atom to which it is bonded.)

6. A step of forming a resist film by applying the radiation-sensitive composition according to any one of claims 1 to 5 onto a substrate, The steps include: exposing the resist film, A step of developing the exposed resist film, A pattern formation method, including the following.

7. The pattern forming method according to claim 6, wherein the developing step is a step of developing the exposed resist film with an alkaline developer.

8. A photodecayable base comprising an anion represented by the following formula (1) or the following formula (r-2) and a monovalent organic cation. 【Transformation 8】 (In formula (1), A １ is an (m+n+2) valent aromatic ring group. In formula (1), "-OH" and "-COO" － " is A １ The atoms bonded to the same benzene ring inside, and to which the "-OH" is bonded, and the "-COO" － The atom to which it bonds is adjacent. １ R is a monovalent group having a cyclic (thio)acetal structure. m is an integer of 1 or more. If m is 2 or more, multiple R １ They are either identical or different. n is a non-negative integer. If n is 1, R ２ is a halogen atom or a substituted or unsubstituted monovalent hydrocarbon group. If n is 2 or more, multiple R ２ These are, independently of each other, a halogen atom, a monovalent hydrocarbon group, or a substituted monovalent hydrocarbon group, or multiple R ２ Two of these atoms are combined with each other to form an alicyclic hydrocarbon structure or aliphatic heterocyclic structure, along with the atoms to which they bond. ＋ (This is a monovalent organic cation.) 【Chemistry 10】 (In formula (r-2), Y1 and Y2 are independently oxygen atoms or sulfur atoms. R3 and R4 are independently hydrogen atoms, halogen atoms, or monovalent organic groups, or R3 and R4 together represent an alicyclic hydrocarbon structure formed with the carbon atoms to which they are bonded. A2 is a tetravalent aromatic ring group. In formula (r-2), "-OH" and "-COO-" are bonded to the same benzene ring in A2, and the atom to which "-OH" is bonded and the atom to which "-COO-" is bonded are adjacent. R5e, R5f, R6e, and R6f are independently hydrogen atoms, halogen atoms, or monovalent organic groups. t4 and t5 are 0.)

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