Radiation-sensitive composition and resist pattern forming method

Abstract

A radiation-sensitive composition comprising a polymer (A) that includes a structural unit represented by formula (i), and an acid-generating compound (excluding said polymer (A)) that has a radiation-sensitive onium cation and an organic anion, and satisfying requirement [K1] and / or requirement [K2]. [K1]: The polymer (A) has a radiation-sensitive onium cation [X] having two or more of at least one type of substituent group β selected from the group consisting of fluoroalkyl groups and fluoro groups (excluding a fluoro group in a fluoroalkyl group). [K2]: The acid-generating compound includes a compound having a radiation-sensitive onium cation [X].

Description

Cross - reference to related applications

[0001] This application is based on Japanese Patent Application No. 2021 - 1955 filed on January 8, 2021, the content of which is incorporated herein by reference.

Technical Field

[0002] The present disclosure relates to a radiation - sensitive composition and a resist pattern forming method.

Background Art

[0003] In lithography technology used in the manufacturing processes of various electronic devices such as semiconductor devices and liquid crystal devices, a radiation - sensitive composition is irradiated with far - ultraviolet rays such as ArF excimer lasers, extreme ultraviolet rays (EUV), electron beams, etc., to generate an acid in the exposed area. A difference in the dissolution rate in the developer between the exposed area and the unexposed area is caused by a chemical reaction in which the generated acid participates, thereby forming a resist pattern on the substrate.

[0004] In various electronic device structures, further miniaturization is rapidly progressing. Along with this, further miniaturization of resist patterns in the lithography process is required. Also, in response to such requirements, various studies have been made to improve the resolution, rectangularity of resist patterns, etc. of chemically amplified radiation - sensitive compositions used for microfabrication by lithography (see, for example, Patent Document 1). Patent Document 1 proposes a chemically amplified resist composition containing an acid generator having a triarylsulfonium cation having one or more fluorine atoms and a resin having a repeating unit having a phenolic hydroxyl group.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, further miniaturization of resist patterns has been rapidly progressing, and for example, attempts have been made to form patterns with a line width of 40 nm or less. Even when forming such fine resist patterns, it is required to form a good resist pattern with a small exposure amount (i.e., high sensitivity).

[0007] Furthermore, for the radiation-sensitive composition used in the lithography process, characteristics such as small CDU (Critical Dimension Uniformity) in hole pattern formation and a sufficient difference in dissolution rate of the exposed part and the unexposed part with respect to the developer and few development residues are required.

[0008] The present disclosure has been made in view of the above problems, and an object thereof is to provide a radiation-sensitive composition and a resist pattern forming method capable of forming a resist pattern with high sensitivity, small CDU, and suppressed occurrence of development defects.

Means for Solving the Problems

[0009] According to the present disclosure, the following means are provided. [1] A (A) polymer containing a structural unit represented by the following formula (i), and an acid generator compound having a radiation-sensitive onium cation structure and an organic anion structure (however, excluding the (A) polymer), and the following requirements [K1] and [K2]; [K1] The (A) polymer has a radiation-sensitive onium cation structure [X] having at least two substituents β selected from the group consisting of a fluoroalkyl group and a fluoro group (however, excluding the fluoro group in the fluoroalkyl group). [K2] The acid generator compound contains a compound having the radiation-sensitive onium cation structure [X]. A radiation-sensitive composition satisfying at least one of the above.

Chemical formula

[0010] [2] A resist pattern forming method including a step of forming a resist film on a substrate using the radiation-sensitive composition of [1] above, a step of exposing the resist film, and a step of developing the exposed resist film.

Effects of the Invention

[0011] According to the radiation-sensitive composition and the resist pattern forming method of the present disclosure, since the sensitivity is high, a good resist pattern can be formed with a small exposure amount. In addition, a resist pattern having a small CDU and few development defects can be formed.

Modes for Carrying Out the Invention

[0012] ≪Radiation-Sensitive Composition≫ The radiation-sensitive composition of the present disclosure (hereinafter, also referred to as "the present composition") is a polymer composition containing a polymer (hereinafter, also referred to as "structural unit (I)") represented by the following formula (i) and an acid-generating compound having a radiation-sensitive onium cation and an organic anion (however, excluding the (A) polymer). The present composition satisfies at least one of the following requirements [K1] and [K2]. [K1] The radiation-sensitive onium cation structure [X] (hereinafter, also referred to as "specific cation structure [X]") of the polymer has at least two substituents β selected from the group consisting of a fluoroalkyl group and a fluoro group (excluding the fluoro group in the fluoroalkyl group). [K2] The acid-generating compound contains a compound having a specific cation structure [X]. [Chemical formula] (In formula (i), R a is a hydrogen atom, a fluoro group, a methyl group or a trifluoromethyl group. R 2 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. n is an integer from 0 to 16. When n is 1, R 3 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. When n is 2 or more, a plurality of R 3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a plurality of R 3 are combined with each other and represent an alicyclic structure having 3 to 20 ring members formed together with the carbon atom or carbon chain to which they are attached.)

[0013] Typically, as a structure for generating an acid, the acid-generating compound contained in this composition has a structure derived from an onium salt having a radiation-sensitive onium cation structure and an organic anion structure (hereinafter, also simply referred to as an organic anion structure) which is a conjugate base of an acid. The organic anion is usually an anion obtained by removing a proton from an acid group of an organic acid. When the radiation acts, the radiation-sensitive onium cation in the acid-generating compound decomposes to release the organic anion, and the released organic anion combines with hydrogen extracted from a component (for example, the acid-generating compound itself or a solvent) contained in this composition, thereby giving an acid to the component contained in this composition. Examples of the acid-generating compound contained in this composition include (B) an acid generator and (C) an acid diffusion controller. Note that the acid-generating compound contained in this composition may be one kind or two or more kinds.

[0014] In addition, the polymer contained in the present composition is classified as "(A) polymer" as long as it has the structural unit (I). Therefore, when the polymer contained in the present composition has a radiation-sensitive onium cation structure and an organic anion structure together with the structural unit (I), the polymer corresponds to the "(A) polymer". That is, the "acid generator compound" in the present specification is distinguished from the (A) polymer in that it does not have the structural unit (I).

[0015] The specific cation structure [X] may be possessed by the (A) polymer or may be possessed by the acid generator compound. Also, both the (A) polymer and the acid generator compound may have the specific cation structure [X]. When the acid generator compound has the specific cation structure [X], the (B) acid generator may have the specific cation structure [X], and the (C) acid diffusion controller may have the specific cation structure [X]. The component having the specific cation structure [X] may be only one kind or two or more kinds. That is, only one kind of the components contained in the present composition may have the specific cation structure [X], or two or more kinds (for example, the (A) polymer and the (B) acid generator) may have the specific cation structure [X].

[0016] The specific cation structure [X] may be a radiation-sensitive onium cation possessed by the polymer, or may be a radiation-sensitive onium cation possessed by a compound different from the polymer (that is, a low-molecular compound). Also, the specific cation structure [X] may constitute at least a part of the radiation-sensitive onium cations in both the polymer and the low-molecular compound. Therefore, when the acid generator compound has the specific cation structure [X], the acid generator compound having the specific cation structure [X] may be a polymer that does not have the structural unit (I) or may be a low-molecular compound. In the present specification, the "low-molecular compound" is a compound different from the polymer, that is, a compound that does not have a repeating unit.

[0017] In the present composition containing the structural unit (I) and the specific cationic structure [X], specific embodiments of the composition that satisfy at least one of the requirements [K1] and [K2] include, for example, the following embodiments <1> to <3>. According to the embodiments <1> to <3>, it is suitable in that a radiation-sensitive composition excellent in sensitivity and CDU performance and having sufficiently little development residue can be obtained.

[0018] <1> An embodiment containing a polymer (A), an acid generator (B), and a solvent (D), and containing, as the acid generator (B), an onium salt having a specific cationic structure [X] and an organic anion structure. <2> An embodiment containing a polymer (A), an acid generator (B), and a solvent (D), wherein the polymer (A) has, together with the structural unit (I), a structural unit having a radiation-sensitive onium cation structure and an organic anion structure (hereinafter also referred to as "structural unit (IV)"), and the structural unit (IV) is a structural unit derived from a monomer having a specific cationic structure [X] and an organic anion structure. <3> An embodiment containing a polymer (A), an acid diffusion control agent (C), and a solvent (D), and containing, as the acid diffusion control agent (C), an onium salt having a specific cationic structure [X] and an organic anion structure.

[0019] Here, the embodiments <1> to <3> may further contain other components other than the components shown in each embodiment. For example, the embodiments <1> to <3> may further contain another component having a specific cationic structure [X]. Specifically, for example, in the embodiment <1>, an onium salt containing a specific cationic structure [X] may be further contained as the acid diffusion control agent (C). Also, in the embodiment <2>, an onium salt containing a specific cationic structure [X] may be further contained as the acid generator (B). Furthermore, the embodiments <1> to <3> may further contain another component not having a specific cationic structure [X]. For example, in the embodiments <1> to <3>, an onium salt composed of a cation not having a specific cationic structure [X] (hereinafter also referred to as "other cation") and an organic anion may be further contained as the acid diffusion control agent (C).

[0020] In the aspects of <1> to <3>, the (B) acid generator and the (C) acid diffusion controller may be low molecular compounds or polymers. When the (B) acid generator and the (C) acid diffusion controller are polymers, the polymer typically has the structural unit (IV). However, a polymer containing the structural unit (I) together with the structural unit (IV) is classified as the (A) polymer in this specification. On the other hand, a polymer having the structural unit (IV) and not having the structural unit (I) is classified as the (B) acid generator or the (C) acid diffusion controller according to the relative acid strength.

[0021] First, the details of the structural unit (I) and the specific cation structure [X] will be described below.

[0022] <Structural unit (I)> The structural unit (I) is a structural unit having an acid dissociable group containing a dicyclopentadiene structure. Here, in this specification, the "acid dissociable group" refers to a group that substitutes a hydrogen atom of an acid group such as a carboxy group or a hydroxy group and dissociates by the action of an acid. By including a polymer having an acid dissociable group in this composition, the acid dissociable group dissociates by the acid generated from the compound having a radiation-sensitive onium cation by exposure, and a carboxy group, a hydroxy group, etc. are generated, and the solubility of the polymer component in the developer can be changed. Thereby, good lithography characteristics can be imparted to this composition, and a good resist pattern can be formed.

[0023] In particular, this composition contains a polymer having a bulky structure (dicyclopentadiene structure) as an acid dissociable group and contains a radiation-sensitive onium cation having two or more substituent βs, whereby the effects of improving the sensitivity and reducing the development residue can be achieved.

[0024] In the above formula (i), R 2 and R 3 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like. Incidentally, R 3is a group bonded to one or more carbon atoms constituting the aliphatic hydrocarbon ring (i.e., dionorbornane skeleton) in formula (i).

[0025] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl group, ethyl group, n-propyl group, and i-propyl group; alkenyl groups such as ethenyl group, propenyl group, and butenyl group; alkynyl groups such as ethynyl group, propynyl group, and butynyl group, and the like. Among these, the monovalent chain hydrocarbon group represented by R 2 and R 3 is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, and still more preferably methyl group, ethyl group, and i-propyl group.

[0026] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monovalent monocyclic alicyclic saturated hydrocarbon groups such as cyclopentyl group and cyclohexyl group; monovalent monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl group and cyclohexenyl group; monovalent polycyclic alicyclic saturated hydrocarbon groups such as norbornyl group, adamantyl group, and tricyclodecyl group; monovalent polycyclic alicyclic unsaturated hydrocarbon groups such as norbornenyl group and tricyclodecenyl group, and the like. Among these, monovalent monocyclic alicyclic saturated hydrocarbon groups and monovalent polycyclic alicyclic saturated hydrocarbon groups are preferred, and cyclopentyl group, cyclohexyl group, norbornyl group, and adamantyl group are more preferred.

[0027] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, methylnaphthyl group, anthryl group, and methylanthryl group; aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group, and the like.

[0028] Examples of the alicyclic structure having 3 to 20 ring members formed by combining a plurality of R 3 with each other include alicyclic saturated hydrocarbon structures such as cyclopentane structure and cyclohexane structure, and the like.

[0029] Among the above, R 2 is preferably an alkyl group having 2 to 10 carbon atoms in terms of being able to increase the dissolved contrast, and more preferably an alkyl group having 2 to 5 carbon atoms in terms of ease of dissociation. R 3 is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms and more preferably a monovalent hydrocarbon group having 1 to 6 carbon atoms in terms of easily controlling the polarity of the polymer having the structural unit (I). n is preferably 0 to 6, more preferably 0 to 3, and still more preferably 0 or 1.

[0030] In addition, in the above formula (i), the arrangement of the polymer main chain with respect to the bicyclo[2.2.1]heptane ring constituting the aliphatic hydrocarbon ring in the formula is not particularly limited, and may be either exo-addition or endo-addition with respect to the bicyclo[2.2.1]heptane ring. In terms of being able to improve the LWR (Line Width Roughness) performance, CDU performance and development residue suppression property of the present composition, among these, in the above formula (i), the arrangement of the polymer main chain is preferably endo-addition with respect to the bicyclo[2.2.1]heptane ring, and specifically, it is preferably a structural unit represented by each of the following formula (i-a) and formula (i-b).

Chemical formula

[0031] Specific examples of the structural unit (I) include structural units represented by each of the following formula (i-1) to formula (i-7).

Chemical formula

[0032] Among the polymer components contained in the composition, the content ratio of the structural unit (I) is preferably 3 mol% or more, more preferably 5 mol% or more, and still more preferably 10 mol% or more, based on all the structural units contained in the (A) polymer. Further, the content ratio of the structural unit (I) 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 contained in the (A) polymer. By setting the content ratio of the structural unit (I) within the above range, the solubility of the (A) polymer can be appropriately adjusted, which is preferable in that development residues can be reduced.

[0033] <Specific Cation Structure [X]> The specific cation structure [X] is not particularly limited as long as it has a radiation-sensitive onium cation structure having two or more substituent βs. Among them, the specific cation structure [X] preferably has a sulfonium cation structure or an iodonium cation structure. The number of substituent βs of the specific cation structure [X] is preferably 3 or more, more preferably 4 or more, in terms of being able to increase the sensitivity while maintaining high CDU performance of the composition and dissolution contrast to the developer. Further, from the viewpoint of balancing the effect of improving sensitivity and ease of synthesis, the number of substituent βs of the specific cation structure [X] is preferably 10 or less, more preferably 8 or less, still more preferably 7 or less, and even more preferably 6 or less. The substituent β is preferably at least one group selected from the group consisting of a fluoro group and a fluoroalkyl group bonded to an aromatic ring, more preferably a fluoro group bonded to an aromatic ring, from the viewpoint of sensitivity.

[0034] In addition, when the specific cation structure [X] has a fluoroalkyl group as the substituent β, the number of fluoroalkyl groups in the specific cation structure [X] is the same as the number of substituent βs of the specific cation structure [X]. Therefore, for example, when the specific cation structure [X] has two trifluoromethyl groups (-CF3), the number of substituent βs of the specific cation structure [X] is 2. Further, when the specific cation structure [X] has one fluoro group (-F) and two trifluoromethyl groups (-CF3) bonded to an aromatic ring, the number of substituent βs of the specific cation structure [X] is 3.

[0035] The bonding position of the substituent β in the specific cationic structure [X] is not particularly limited. In terms of a high effect of improving the sensitivity of the composition, at least one of the substituents β of the specific cationic structure [X] is preferably directly bonded to the aromatic ring contained in the specific cationic structure [X], and more preferably two or more substituents β are directly bonded to the aromatic ring. Among them, in particular, the specific cationic structure [X] has one or more aromatic rings (hereinafter also referred to as "aromatic ring Z") bonded to a sulfonium cation or an iodonium cation, and it is preferable that two or more substituents β are bonded to the same or different aromatic rings Z. That is, the specific cationic structure [X] has one or more aromatic rings Z, and one or more of the aromatic rings Z have a structure in which two or more substituents β are bonded to the same aromatic ring, or has two or more aromatic rings Z, and it is preferable that one or more substituents β are bonded to each of two or more different aromatic rings among the aromatic rings Z.

[0036] Examples of the aromatic ring Z include a benzene ring, a naphthalene ring, an anthracene ring, and the like. Among these, the aromatic ring Z is preferably a benzene ring or a naphthalene ring, and particularly preferably a benzene ring. The number of aromatic rings Z of the specific cationic structure [X] is not particularly limited, but one or more is preferable, and two or more is more preferable. Regarding the total number of substituents β bonded to the aromatic ring Z in the specific cationic structure [X], the description of the number of substituents β of the specific cationic structure [X] applies. That is, the total number of substituents β bonded to the aromatic ring Z is preferably three or more, and more preferably four or more. Also, from the viewpoint of achieving a balance between the effect of improving sensitivity and ease of synthesis, the total number of substituents β bonded to the aromatic ring Z is preferably ten or less, more preferably eight or less, still more preferably seven or less, and even more preferably six or less.

[0037] The specific cationic structure [X] preferably has, among others, a triarylsulfonium cation structure or a diaryliodonium cation structure. Specifically, the specific cationic structure [X] is preferably a partial structure represented by the following formula (1) or a structure represented by the following formula (2).

Chemical formula

[0038] In the above formulas (1) and (2), R 1a , R 2a , R 3a , R 7a and R 8aThe fluoroalkyl group may be linear or branched. The fluoroalkyl group preferably has 1 to 10 carbon atoms. For example, trifluoromethyl group, 2,2,2-trifluoroethyl group, perfluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro-n-propyl group, perfluoroisopropyl group, perfluoro-n-butyl group, perfluoroisobutyl group, perfluoro-t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group, etc. can be exemplified. Among these, R 1a 、R 2a 、R 3a 、R 7a and R 8a The fluoroalkyl group preferably has 1 to 5 carbon atoms, and trifluoromethyl group, 2,2,2-trifluoroethyl group or perfluoroethyl group is more preferable.

[0039] R 1a 、R 2a 、R 3a 、R 7a and R 8a Among the above, it is preferably a fluoro group, trifluoromethyl group, 2,2,2-trifluoroethyl group or perfluoroethyl group, more preferably a fluoro group or trifluoromethyl group, and particularly preferably a fluoro group. By using an onium salt having a structure in which a fluoro group is directly bonded to an aromatic ring in a triarylsulfonium cation structure or a diaryliodonium cation structure, the sensitivity of the present composition can be further improved, and a composition excellent in CDU performance and development residue suppression can be obtained, which is preferable.

[0040] In the above formulas (1) and (2), the monovalent substituents represented by R 4a 、R 5a 、R 6a 、R 9a and R 10a are different groups from substituent β. R 4a 、R 5a 、R 6a 、R 9a and R10a Specific examples of the monovalent substituent represented by the formula (I) include a chloro group, a bromo group, an iodo group, a substituted or unsubstituted alkyl group (excluding a fluoroalkyl group), a substituted or unsubstituted alkoxy group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkyloxy group, an ester group, an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, and a nitro group.

[0041] R 4a , R 5a , R 6a , R 9a and R 10a The alkyl group represented by the formula (I) may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, and a neopentyl group. 4a , R 5a , R 6a , R 9a and R 10a The alkyl group in R preferably has 1 to 5 carbon atoms, and more preferably is a methyl group, an ethyl group, an n-butyl group, or a t-butyl group. 4a , R 5a , R 6a , R 9a and R 10a When the alkyl group has a substituent, examples of the substituent include a chloro group, a bromo group, an iodo group, a hydroxy group, a carboxy group, a cyano group, a nitro group, and an alkoxy group having 1 to 5 carbon atoms.

[0042] R 4a , R 5a , R 6a , R 9a and R 10a Specific examples of the alkoxy group in which is a substituted or unsubstituted alkoxy group include groups having the above-mentioned substituted or unsubstituted alkyl groups in the alkyl group moiety constituting the alkoxy group. The alkoxy group is particularly preferably a methoxy group, an ethoxy group, an n-propoxy group, or an n-butoxy group.

[0043] R 4a 、R 5a 、R 6a 、R 9a and R 10a The cycloalkyl group represented by R 4a , R 5a , R 6a , R 9a , and R 10a may be either monocyclic or polycyclic. Among these, examples of the monocyclic cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, etc. Examples of the polycyclic cycloalkyl group include a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group, etc. R 4a 、R 5a 、R 6a 、R 9a and R 10a When the cycloalkyl group of R 4a , R 5a , R 6a , R 9a , and R 10a has a substituent, examples of the said substituent include a chloro group, a bromo group, an iodo group, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group having 1 to 5 carbon atoms, etc.

[0044] R 4a 、R 5a 、R 6a 、R 9a and R 10a Specific examples when R 4a , R 5a , R 6a , R 9a , and R 10a are a substituted or unsubstituted cycloalkyloxy group include groups having a substituted or unsubstituted cycloalkyl group exemplified above in the cycloalkyl group part constituting the cycloalkyloxy group. It is particularly preferable that the said alkoxy group is a cyclopentyloxy group or a cyclohexyloxy group.

[0045] R 4a 、R 5a 、R 6a 、R 9a and R 10a When R 4a , R 5a , R 6a , R 9a , and R 10a are an ester group (-COOR), examples of the hydrocarbon part (R) of the said ester group include a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group exemplified above. Among these, R 4a 、R 5a 、R 6a 、R 9a and R 10aWhen is an ester group, it is preferably a methoxycarbonyl group, an ethoxycarbonyl group, or an n-butoxycarbonyl group.

[0046] R 4a , R 5a , R 6a , R 9a and R 10a When R is an alkylsulfonyl group, the alkyl group moiety constituting the alkylsulfonium group may be the substituted or unsubstituted alkyl groups exemplified above. 4a , R 5a , R 6a , R 9a and R 10a When is a cycloalkylsulfonyl group, examples of the alkyl group constituting the cycloalkylsulfonium group include the substituted or unsubstituted cycloalkyl groups exemplified above.

[0047] R 4a and R 5a When R are combined with each other to represent a divalent group linking the rings to which they are bonded, examples of the divalent group include -COO-, -OCO-, -CO-, -O-, -SO-, -SO2-, -S-, an alkanediyl group having 1 to 3 carbon atoms, an alkenediyl group having 2 or 3 carbon atoms, and a group having -O-, -S-, -COO-, -OCO-, -CO-, -SO-, or -SO2- between the carbon-carbon bonds of an ethylene group. 4a and R 5a are taken together to form a single bond or a divalent group connecting the rings to which they are attached, R 4a and R 5a preferably forms a single bond, -O- or -S-.

[0048] The total number of a1, a2, and a3 is 2 or more, preferably 3 or more, further preferably 3 to 6, and even more preferably 4 to 6. The total number of a7 and a8 is 2 or more, and more preferably 2 to 6.

[0049] In the above formulas (1) and (2), the bond (*) may be bonded to a hydrogen atom or may be bonded to a monovalent group (such as a fluoro group, a hydroxy group, an alkyl group, etc.). Alternatively, it may be bonded to an atom constituting the main chain or side chain of the polymer.

[0050] Specific examples of the specific cation structure [X] include, for example, a structure represented by the following formula and a structure in which one arbitrary hydrogen atom is removed from the benzene ring of the organic cation represented by the following formula, etc. However, the structure possessed by the specific cation [X] is not limited to the following structure.

Chemical formula

Chemical formula

Chemical formula

[0051] The organic anion that serves as the counterion of the specific cation structure [X] only needs to have a structure capable of generating an acid upon irradiation with radiation and is not particularly limited. Examples of the structure possessed by the organic anion include a sulfonate anion structure, an imide anion structure, a methyl anion structure, a carboxylate anion structure, etc. Among these, the organic anion preferably has a sulfonate anion structure or a carboxylate anion structure.

[0052] <Regarding the specific embodiments of the present composition> One preferred embodiment of the present composition is a polymer composition containing (A) a polymer and (B) an acid generator, and may further contain one or more of (C) an acid diffusion controller, (D) a solvent, and (E) a highly fluorine-containing polymer as suitable components. Hereinafter, each component will be described in detail.

[0053] <(A) Polymer> (A) The polymer is a polymer having the structural unit (I) described above. (A) The polymer preferably constitutes the base resin of the present composition. Here, in this specification, the "base resin" means a component that occupies 50% by mass or more of the total solid content contained in the present composition. The present composition may contain only one kind of (A) polymer, or may contain two or more kinds. In addition, in this specification, the "total solid content" is the sum of components other than the (D) solvent.

[0054] (A) The content ratio of the structural unit (I) is preferably 3 mol% or more, more preferably 5 mol% or more, and still more preferably 10 mol% or more with respect to all the structural units constituting the (A) polymer. Further, the content ratio of the structural unit (I) is preferably 80 mol% or less, more preferably 70 mol% or less, and still more preferably 65 mol% or less with respect to all the structural units constituting the (A) polymer. By setting the content ratio of the structural unit (I) within the above range, it is suitable in terms of enabling good sensitivity of the present composition.

[0055] [Other Structural Units] (A) The polymer may further have a structural unit different from the structural unit (I) (hereinafter, also referred to as "other structural units"). Examples of the other structural units include the following structural units (II) to (VI). Structural unit (II): A structural unit having a hydroxyl group bonded to an aromatic ring Structural unit (III): A structural unit having an acid dissociable group not containing a dicyclopentadiene structure Structural unit (IV): A structural unit having a radiation-sensitive onium cation and an organic anion Structural unit (V): Having a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure combining two or more of these Structural unit (VI): A structural unit having an alcoholic hydroxyl group

[0056] [Structural Unit (II)] (A) The polymer preferably further has a structural unit (II) having a hydroxyl group bonded to an aromatic ring. By introducing the structural unit (II) into the (A) polymer, it is suitable in that the lithography characteristics (such as LWR performance and CDU performance) of the present composition can be sufficiently enhanced.

[0057] Examples of the aromatic ring of the structural unit (II) include a benzene ring, a naphthalene ring, an anthracene ring, and the like. Among these, a benzene ring or a naphthalene ring is preferable, and a benzene ring is more preferable. In the structural unit (II), the number of hydroxyl groups bonded to the aromatic ring is not particularly limited, but is preferably 1 to 3, and more preferably 1 or 2. Examples of the structural unit (II) include a structural unit represented by the following formula (ii).

Chemical formula

[0058] In the above formula (ii), R 1 is preferably a hydrogen atom or a methyl group from the viewpoint of the copolymerizability of the monomer giving the structural unit (II). L 2 is preferably a single bond or -COO-.

[0059] Specific examples of the structural unit (II) include structural units represented by the following formulas (1-1) to (1-12).

Chemical formula

[0060] (A) The proportion of structural unit (II) in the polymer is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 20 mol% or more based on all the structural units constituting the (A) polymer. Also, the proportion of structural unit (II) is preferably 80 mol% or less, more preferably 70 mol% or less, and still more preferably 60 mol% or less based on all the monomers constituting the (A) polymer. Setting the proportion of structural unit (II) within the above range is preferable in that the lithography characteristics (such as LWR performance and CDU performance) of the present composition can be made sufficiently high.

[0061] In addition, from the viewpoint of sufficiently enhancing the LWR performance, CDU performance, etc. of the composition, the present composition preferably contains a polymer having structural unit (II), and its mode is not particularly limited. Therefore, the present composition may contain a polymer having structural unit (II) separately from the polymer having structural unit (I) (i.e., the (A) polymer). Specific modes of the present composition in this case include, for example, a mode containing a polymer having structural unit (I) and not having structural unit (II) and a polymer having structural unit (II) and not having structural unit (I); a mode containing a polymer having structural units (I) and (II) and a polymer having structural unit (II) and not having structural unit (I), etc. From the viewpoint of obtaining a composition excellent in lithography characteristics such as defect suppression property, LWR performance, and CDU performance, the present composition preferably contains at least a polymer having structural units (I) and (II) as the (A) polymer.

[0062] [Structural unit (III)] The structural unit (III) is a structural unit having an acid dissociable group. The structural unit (III) is different from the structural unit (I) in that it does not have a d norbornane structure. The structural unit (III) is a group that substitutes the hydrogen atom of an acid group such as a carboxy group or a hydroxy group, and it suffices to have a group (acid dissociable group) that dissociates by the action of an acid, and it is not particularly limited. Specific examples of the structural unit (III) include a structural unit represented by the following formula (iii-1) (hereinafter, also referred to as "structural unit (III-1)"), and a structural unit represented by the following formula (iii-2) (hereinafter, also referred to as "structural unit (III-2)"), and the like.

Chemical formula

[0063] In the above formulas (iii-1) and (iii-2), R 12 is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of the copolymerizability of the monomer that gives the structural unit (III-1). R 16 is preferably a hydrogen atom, from the viewpoint of the copolymerizability of the monomer that gives the structural unit (III-2).

[0064] R 13 ~R 15 and R 17 ~R 19 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by ~R and R include, for example, a monovalent linear hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like. Specific examples thereof include, as the monovalent linear hydrocarbon group having 1 to 20 carbon atoms, an alkyl group such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, pentyl group; an alkenyl group such as ethenyl group, propenyl group, butenyl group, pentenyl group; an alkynyl group such as ethynyl group, propynyl group, butynyl group, pentynyl group, and the like.

[0065] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a monocyclic alicyclic saturated hydrocarbon group such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group; a polycyclic alicyclic saturated hydrocarbon group such as norbornyl group, adamantyl group, tricyclodecyl group, tetracyclododecyl group; a monocyclic alicyclic unsaturated hydrocarbon group such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group; a polycyclic alicyclic saturated hydrocarbon group such as norbornenyl group, tricyclodecenyl group, and the like. Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include an aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, anthryl group; an aralkyl group such as benzyl group, phenethyl group, naphthylmethyl group, anthrylmethyl group, and the like.

[0066] R 14 and R 15 are combined with each other to form R 14 and R 15Examples of the alicyclic structure having 3 to 20 carbon atoms constituted together with the carbon atom to which is bonded include monocyclic alicyclic structures such as a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, and a cyclooctane structure; and polycyclic alicyclic structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure. R 17 , R 18 and R 19 Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include the above-mentioned R 13 ~R 15 and R 17 ~R 19 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include those having an oxygen atom at the bond-side terminal of the above-mentioned examples. R 17 , R 18 and R 19 Of these, a chain hydrocarbon group and a cycloalkyloxy group are preferred.

[0067] Specific examples of the structural unit (III-1) include structural units represented by the following formulas. [ka] [ka] (In the formula, R A1 is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.

[0068] Specific examples of the structural unit (III-2) include structural units represented by the following formulas. [ka] (In the formula, R 16 is a hydrogen atom or a methyl group.

[0069] (A) In the polymer, the total content ratio of structural unit (I) and structural unit (III) is preferably 20 mol% or more, more preferably 25 mol% or more, and still more preferably 30 mol% or more with respect to all the structural units constituting the (A) polymer. Further, the total content ratio of structural unit (I) and structural unit (III) is preferably 80 mol% or less, more preferably 70 mol% or less, and still more preferably 65 mol% or less with respect to all the structural units constituting the (A) polymer. By setting the content ratio of structural unit (III) within the above range, it is suitable in that the difference in the dissolution rate of the exposed portion and the unexposed portion in the developer can be made sufficiently large, and the pattern shape of the resist film can be made good.

[0070] [Structural unit (IV)] Structural unit (IV) is typically a structural unit derived from an onium salt having a group participating in polymerization (preferably a polymerizable carbon-carbon unsaturated bond-containing group). By the (A) polymer having such a structural unit (IV), it is suitable in that the effect of reducing development residues can be made higher. Specifically, structural unit (IV) can be represented as a structural unit derived from a monomer represented by the following formula (4A) or formula (4B). [Chemical formula] (In formula (4A), L 7 is a group participating in polymerization. "L 7 -Z + " is a radiation-sensitive onium cation. "M - " is an organic anion. In formula (4B), L 7 is a group participating in polymerization. "Z + " is a radiation-sensitive onium cation. "L 7 -M - " is an organic anion.)

[0071] In the above formula (4A) and formula (4B), as the group represented by L 7 , a group containing a polymerizable carbon-carbon unsaturated bond is preferable. Specifically, for example, a vinyl group, a vinyl ether group, a vinylphenyl group, a (meth)acryloyl group, a maleimide group, etc. can be mentioned.

[0072] Among these, the structural unit (IV) is preferably a structural unit derived from the monomer represented by the above formula (4B) in terms of ease of polymer synthesis.

[0073] The radiation-sensitive onium cation contained in the monomer constituting the structural unit (IV) may be a radiation-sensitive onium cation having two or more substituent βs, or a radiation-sensitive onium cation having only one substituent β or no substituent β (hereinafter also referred to as "other organic cation"). Examples of the monomer constituting the structural unit (IV) include the following monomers [A1] and [A2]. [A1] A monomer composed of a radiation-sensitive onium cation having two or more substituent βs and an organic anion, and either the radiation-sensitive onium cation having two or more substituent βs or the organic anion contains a group participating in polymerization. [A2] A monomer composed of another organic cation and an organic anion, and either the other organic cation or the organic anion contains a group participating in polymerization.

[0074] Preferable examples of the structural unit (IV) include a structural unit represented by the following formula (iv-1), a structural unit represented by the following formula (iv-2), and a structural unit represented by the following formula (iv-3). [Chemical formula] (In formula (iv-1), R 20 is a hydrogen atom or a methyl group. L 4 is a single bond, -O-, or -COO-. R 23 is a substituted or unsubstituted alkanediyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenediyl group having 2 to 6 carbon atoms, or a substituted or unsubstituted arylene group having 6 to 12 carbon atoms. R 21 and R 22 are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 12 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. M - is an organic anion. In formula (iv-2), R 20 is a hydrogen atom or a methyl group. L 5 is a single bond, -R 30a -CO-O-, -R 30a -O-, or -R 30a -O-CO-. R 30a is an alkanediyl group having 1 to 12 carbon atoms, or a divalent group containing -O-, -CO-, or -COO- between the carbon-carbon bonds of an alkanediyl group having 2 to 12 carbon atoms. R 24 is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a fluoroalkyl group having 1 to 10 carbon atoms. Y + is a radiation-sensitive onium cation represented by the following formula (Y-1) or formula (Y-2). In formula (iv-3), R 20 is a hydrogen atom or a methyl group. L 6 is a single bond, a substituted or unsubstituted alkanediyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenediyl group having 2 to 6 carbon atoms, a substituted or unsubstituted arylene group having 6 to 12 carbon atoms, -CO-O-R 30b -, or -CO-NH-R 30b -. R 30b is a substituted or unsubstituted alkanediyl group having 1 to 6 carbon atoms, or a divalent group containing -O-, -CO-, or -COO- between the carbon-carbon bonds of an alkanediyl group having 2 to 6 carbon atoms. Y + is a radiation-sensitive onium cation represented by the following formula (Y-1) or formula (Y-2).)

Chemical formula

[0075] In the above formulas (iv-1) to (iv-3), and in the above formulas (Y-1) and (Y-2), R 21 ~R 23and R 25 ~R 29 When each of the groups of ~R is a substituted alkyl group, a substituted alkenyl group, or a substituted aryl group, examples of the substituent include a fluoro group, a chloro group, a bromo group, an iodo group, an alkoxy group, a cycloalkyloxy group, an ester group, an alkylsulfonyl group, a cycloalkylsulfonyl group, a hydroxy group, a carboxy group, a cyano group, a nitro group, an acetyl group, a fluoroacetyl group, and the like.

[0076] The organic cation in the monomer constituting the structural unit represented by the above formula (iv-1) and the organic cation represented by the above formula (Y-1) preferably have a triarylsulfonium cation structure. The organic cations in the above formulas (iv-2) and (iv-3) preferably have a triarylsulfonium cation structure or a diaryliodonium cation structure. The organic cation represented by the above formula (Y-2) preferably has a diaryliodonium cation structure. When the monomer constituting the structural unit represented by the above formula (iv-1), the structural unit represented by the above formula (iv-2), and the structural unit represented by the above formula (iv-3) have a specific cation structure [X], specific examples of the specific cation structure [X] include the structures exemplified above.

[0077] Specific examples of the structural unit (IV) include, for example, structural units represented by each of the following formulas (iv-1a) to (iv-7a) as structural units having the partial structure represented by the above formula (4B). Structural units having the partial structure represented by the above formula (4A) include structural units represented by each of the following formulas (iv-8a) and (iv-9a). [Chemical formula] (In formulas (iv-1a) to (iv-9a), R 20 is a hydrogen atom or a methyl group. Y + is a radiation-sensitive onium cation represented by the above formula (Y-1) or formula (Y-2). M - is an organic anion.)

[0078] (A) When the polymer contains the structural unit (IV), the content ratio of the structural unit (IV) is preferably 3 mol% or more, more preferably 5 mol% or more, and still more preferably 10 mol% or more with respect to all the structural units constituting the (A) polymer. Further, the content ratio of the structural unit (IV) is preferably 50 mol% or less, more preferably 35 mol% or less, and still more preferably 25 mol% or less with respect to all the structural units constituting the (A) polymer. By setting the content ratio of the structural unit (IV) within the above range, it is possible to particularly suppress the decrease in resolution associated with acid diffusion, and as a result, it is preferable in that the lithography property of the present composition can be further improved.

[0079] [Structural unit (V)] The structural unit (V) is a structural unit having a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure formed by combining two or more of these (excluding those corresponding to the structural units (I) to (IV)). By further including the structural unit (V) in the (A) polymer, the solubility in the developer can be adjusted, and as a result, it is preferable in that the lithography characteristics of the present composition can be further improved. Further, by further including the structural unit (V) in the (A) polymer, the adhesion between the resist film obtained using the present composition and the substrate can be improved.

[0080] Examples of the structural unit (V) include structural units represented by the following formulae. [Chemical formula] [Chemical formula] [Chemical formula] [Chemical formula] (In the formula, R L1 is a hydrogen atom, a fluoro group, a methyl group or a trifluoromethyl group.)

[0081] When the polymer (A) contains the structural unit (V), the content ratio of the structural unit (V) is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 15 mol% or more, based on all the structural units constituting the polymer (A). Further, the content ratio of the structural unit (V) is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 30 mol% or less, based on all the structural units constituting the polymer (A). By setting the content ratio of the structural unit (V) within the above range, it is suitable in terms of improving the lithography characteristics of the present composition and improving the adhesion of the resist film obtained using the present composition to the substrate.

[0082] [Structural unit (VI)] The structural unit (VI) is a structural unit having an alcoholic hydroxyl group (excluding those corresponding to the structural units (I) to (V)). Here, in the present specification, the "alcoholic hydroxyl group" is a group having a structure in which a hydroxyl group is directly bonded to an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a chain hydrocarbon group or an alicyclic hydrocarbon group. By further having the structural unit (VI) in the polymer (A), the solubility in the developer can be improved, and as a result, it is suitable in terms of further improving the lithography characteristics of the present composition.

[0083] The structural unit (VI) is preferably a structural unit derived from an unsaturated monomer having an alcoholic hydroxyl group. The unsaturated monomer is not particularly limited, and examples thereof include 3-hydroxyadamantan-1-yl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and the like.

[0084] When the polymer (A) has the structural unit (VI), the content ratio of the structural unit (VI) is preferably 1 mol% or more, more preferably 3 mol% or more, based on all the structural units constituting the polymer (A). Further, the content ratio of the structural unit (VI) is preferably 30 mol% or less, more preferably 10 mol% or less, based on all the structural units constituting the polymer (A).

[0085] Examples of other structural units include, in addition to the above, structural units containing a cyano group, a nitro group, or a sulfonamide group (e.g., structural units derived from 2-cyanomethyladamantan-2-yl (meth)acrylate, etc.), structural units containing a halogen atom (e.g., structural units derived from 2,2,2-trifluoroethyl (meth)acrylate, structural units derived from 1,1,1,3,3,3-hexafluoropropan-2-yl (meth)acrylate, structural units derived from 4-iodostyrene, etc.), and structural units containing a non-acid dissociable hydrocarbon group (e.g., structural units derived from styrene, structural units derived from vinylnaphthalene, structural units derived from n-pentyl (meth)acrylate, etc.). The content ratio of these structural units can be appropriately set according to each structural unit as long as the effects of the present disclosure are not impaired.

[0086] The content ratio of the (A) polymer in the present composition is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more with respect to the total amount of the solid content contained in the present composition. Also, the content ratio of the (A) polymer is preferably 99% by mass or less, more preferably 98% by mass or less, and still more preferably 95% by mass or less with respect to the total amount of the solid content contained in the present composition. By setting the ratio of the (A) polymer to the total amount of the solid content contained in the present composition within the above range, the sensitivity and CDU performance of the present composition can be improved, and it is preferable in that the effect of improving the suppression of development residues can be sufficiently obtained.

[0087] <Synthesis of Polymer> (A) The polymer can be synthesized, for example, by polymerizing monomers that provide each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0088] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. As the radical polymerization initiator, one kind can be used alone or two or more kinds can be used in combination.

[0089] Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; ketones such as acetone, butanone, 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. As the solvent used for the polymerization, one kind can be used alone or two or more kinds can be used in combination.

[0090] The reaction temperature in the polymerization is preferably 40°C or higher, more preferably 50°C or higher. Also, the reaction temperature is preferably 150°C or lower, more preferably 120°C or lower. The reaction time in the polymerization is preferably 1 hour or longer, more preferably 2 hours or longer. Also, the reaction time is preferably 48 hours or shorter, more preferably 24 hours or shorter.

[0091] (A) The weight average molecular weight (Mw) in terms of polystyrene of the polymer by gel permeation chromatography (GPC) is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, and particularly preferably 5,000 or more. Further, Mw is preferably 50,000 or less, more preferably 30,000 or less, still more preferably 20,000 or less, and particularly preferably 10,000 or less. By setting the Mw of the (A) polymer within the above range, the coatability of the present composition can be improved, and development defects can be sufficiently suppressed, which is preferable.

[0092] (A) The ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene of the polymer by GPC is preferably 5.0 or less, more preferably 3.0 or less, and still more preferably 2.0 or less. Further, Mw / Mn is usually 1 or more, and preferably 1.3 or more.

[0093] <(B) Acid generator> (B) The acid generator is typically a substance containing a radiation-sensitive onium cation and an organic anion. The (B) acid generator may be a low molecular compound or a polymer (excluding the (A) polymer).

[0094] Specific examples of the case where the (B) acid generator is a low molecular compound include, for example, the following onium salts [LB1] and [LB2]. [LB1] An onium salt composed of a radiation-sensitive onium cation having two or more substituent βs and an organic anion. [LB2] An onium salt composed of another organic cation and an organic anion.

[0095] · Specific cation structure [X] In the onium salt [LB1], examples of the specific cation structure [X] include a radiation-sensitive onium cation having a partial structure represented by the above formula (1) and a radiation-sensitive onium cation having a partial structure represented by the above formula (2). Specific examples thereof include the radiation-sensitive onium cations exemplified in the description of the above formula (1) and formula (2).

[0096] · Other organic cations In the onium salt [LB2], the other organic cation may be a radiation-sensitive onium cation having no substituent β or only one substituent β, and its structure is not particularly limited. From the viewpoint of improving the lithography characteristics of the present composition, the other organic cation preferably has a sulfonium cation structure or an iodonium cation structure. Specifically, an organic cation represented by the following formula (4), an organic cation represented by the following formula (5), an organic cation represented by the following formula (6), and the like can be mentioned.

[0097] [Chemical formula] (In formula (4), R 31 and R 32 are each independently a monovalent organic group having 1 to 20 carbon atoms. k1 is an integer of 0 to 5. When k1 is 1, R 33 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. When k1 is 2 or more, a plurality of R 33 are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group, or two or more of the plurality of R 33 are combined with each other and represent a part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded. t1 is 0 or 1. However, in formula (4), the number of substituent β is 0 or 1. In formula (5), k2 is an integer of 0 to 7. When k2 is 1, R 34 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group. When k2 is 2 or more, a plurality of R 34 are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen group, or two or more of the plurality of R 34 are combined with each other and represent a part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded. k3 is an integer of 0 to 6. When k3 is 1, R 35is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group. When k3 is 2 or more, a plurality of R 35 are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group, or two or more of the plurality of R 35 represent a part of a ring structure having 3 to 20 ring members formed together with the carbon chain to which they are bonded. t3 is an integer of 0 to 3. R 36 is a single bond or a divalent organic group having 1 to 20 carbon atoms. t2 is 0 or 1. However, in formula (5), the number of substituent β is 0 or 1. In formula (6), k4 is an integer of 0 to 5. When k4 is 1, R 37 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group. When k4 is 2 or more, a plurality of R 37 are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group, or two or more of the plurality of R 37 represent a part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded. k5 is an integer of 0 to 5. When k5 is 1, R 38 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group. When k5 is 2 or more, a plurality of R 38 are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen group, or two or more of the plurality of R 38 represent a part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded. However, in formula (6), the number of substituent β is 0 or 1.)

[0098] In the above formula (4), R 31 R 32 and R 33The monovalent organic group having 1 to 20 carbon atoms represented by is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent hydrocarbon group having 1 to 20 carbon atoms in which a hydrogen atom is substituted by a substituent, more preferably a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in which a hydrogen atom is substituted by a substituent, and still more preferably a substituted or unsubstituted phenyl group. Note that R 31 、R 32 and R 33 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include the same groups as those exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R 13 ~R 15 and R 17 ~R 19 in the above formulas (iii-1) and (iii-2).

[0099] R 31 、R 32 and R 33 Examples of the substituent of the group represented by include the same groups as those exemplified as the monovalent substituent represented by R 4a 、R 5a 、R 6a 、R 9a and R 10a in the above formulas (1) and (2). k1 is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0. t1 is preferably 0.

[0100] In the above formula (5), R 34 and R 35 are preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, -OR k , -COOR k , -O-CO-R k , -O-R kk -COOR k or -R kk -CO-R k is preferable. R k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. R 34 and R 35Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula include the groups exemplified as the groups represented by R 13 ~R 15 and R 17 ~R 19 in the above formulas (iii-1) and (iii-2). Further, examples of the substituent that substitutes the hydrogen atom of the hydrocarbon group in R 34 and R 35 include the same groups as the groups exemplified as the substituents of the groups represented by the above R 31 、R 32 and R 33 . Examples of the divalent organic group represented by R 36 include groups obtained by removing one hydrogen atom from the monovalent organic groups having 1 to 20 carbon atoms exemplified as R 34 and R 35 , etc. k3 is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0. t2 is preferably 0. t3 is preferably 2 or 3, and more preferably 2.

[0101] In the above formula (6), R 37 and R 38 are preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, -OSO2-R k , -SO2-R k , -OR k , -COOR k , -O-CO-R k , -O-R kk -COOR k , -R kk -CO-R k or -S-R k , or a ring structure formed by combining two or more of these groups with each other. Note that R k and R kk are synonymous with R 34 and R 35 represented by the groups represented by the above R k and R kk . R 37 and R 38Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula include the groups exemplified as the groups represented by R 13 ~R 15 and R 17 ~R 19 in the above formulas (iii-1) and (iii-2). Further, in R 37 and R 38 , examples of the substituent that substitutes the hydrogen atom of the hydrocarbon group include the same groups as the groups exemplified as the substituents of the groups represented by the above R 31 , R 32 and R 33 . k4 and k5 are preferably integers of 0 to 2, more preferably 0 or 1, and still more preferably 0.

[0102] Among these, other organic cations are preferably the radiation-sensitive onium cations represented by the above formula (4) and the radiation-sensitive onium cations represented by the above formula (6), and more preferably radiation-sensitive onium cations having a triarylsulfonium cation structure or a diaryliodonium cation structure. Specifically, other organic cations are radiation-sensitive onium cations that satisfy a1 + a2 + a3 ≤ 1 in the above formula (1) and radiation-sensitive onium cations that satisfy a7 + a8 ≤ 1 in the above formula (2) (wherein "*" in the formulas (1) and (2) represents a bond to a hydrogen atom), which is particularly preferable from the viewpoint of improving the lithography characteristics of the present composition.

[0103] ·Organic anion In the onium salts [LB1] and [LB2], the organic anion is not particularly limited, and examples thereof include organic anions having a sulfonate anion structure, an imide anion structure, or a methide anion structure. Among these, organic anions having a sulfonate anion structure are preferable. Specifically, as the organic anion in the (B) acid generator, the organic anion represented by the following formula (7) can be preferably used.

Chemical formula

[0104] In the above formula (7), examples of the monovalent group containing a ring structure with 5 or more ring members represented by R p1 include a monovalent group containing an alicyclic structure with 5 or more ring members, a monovalent group containing an aliphatic heterocyclic structure with 5 or more ring members, a monovalent group containing an aromatic ring structure with 5 or more ring members, a monovalent group containing an aromatic heterocyclic structure with 5 or more ring members, and the like.

[0105] Examples of the alicyclic structure having 5 or more ring members include monocyclic cycloalkane structures such as cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure, cyclononane structure, cyclodecane structure, cyclododecane structure, etc.; monocyclic cycloalkene structures such as cyclopentene structure, cyclohexene structure, cycloheptene structure, cyclooctene structure, cyclodecene structure, etc.; polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure, tetracyclododecane structure, etc.; polycyclic cycloalkene structures such as norbornene structure, tricyclodecene structure, etc.

[0106] Examples of the aliphatic heterocyclic structure having 5 or more ring members include lactone structures such as hexanolactone structure, norbornanelactone structure, etc.; sultone structures such as hexanosultone structure, norbornanesultone structure, etc.; oxygen atom-containing heterocyclic structures such as oxacycloheptane structure, oxanorbornane structure, cyclic acetal structure, etc.; nitrogen atom-containing heterocyclic structures such as azacyclohexane structure, diazabicyclooctane structure, etc.; sulfur atom-containing heterocyclic structures such as thiacyclohexane structure, thianorbornane structure, etc.

[0107] Examples of the aromatic ring structure having 5 or more ring members include benzene structure, naphthalene structure, phenanthrene structure, anthracene structure, etc. Examples of the aromatic heterocyclic structure having 5 or more ring members include oxygen atom-containing heterocyclic structures such as furan structure, pyran structure, benzopyran structure, etc.; nitrogen atom-containing heterocyclic structures such as pyridine structure, pyrimidine structure, indole structure, etc.

[0108] Note that p1 some or all of the hydrogen atoms of the ring structure of R may be substituted with substituents. Examples of the substituents include fluoro group, chloro group, bromo group, iodo group, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, etc.

[0109] R p1Among them, the monovalent group represented by is preferably a group having an aromatic ring structure with 5 or more ring members, and particularly preferably a group having a benzene structure. Also, R p1 The monovalent group represented by is preferably a group having an aromatic ring structure substituted with a halogen group, and more preferably a group having an aromatic ring structure substituted with one or more iodine groups. In this case, R p1 In the monovalent group represented by, the number of iodine groups bonded to the aromatic ring is more preferably 2 or more, and particularly preferably 3 or more.

[0110] R p2 Examples of the divalent linking group represented by include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, and the like. Among these, a carbonyloxy group, a sulfonyl group, an alkanediyl group or a cycloalkanediyl group is preferable, a carbonyloxy group or a cycloalkanediyl group is more preferable, a carbonyloxy group or a norbornanediyl group is still more preferable, and a carbonyloxy group is particularly preferable.

[0111] R p3 And R p4 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by include an alkyl group having 1 to 20 carbon atoms and the like. R p3 And R p4 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by include a fluorinated alkyl group having 1 to 20 carbon atoms and the like. R p3 And R p4 Is preferably a hydrogen atom, a fluoro group or a fluoroalkyl group, more preferably a fluoro group or a perfluoroalkyl group, and still more preferably a fluoro group or a trifluoromethyl group.

[0112] R p5 And R p6 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by include a fluorinated alkyl group having 1 to 20 carbon atoms and the like. R p5 And R p6As for this, a fluoro group or a fluoroalkyl group is preferable, a fluoro group or a perfluoroalkyl group is more preferable, a fluoro group or a trifluoromethyl group is still more preferable, and a fluoro group is particularly preferable. When n3 is 1, R p5 and R p6 are both fluoro groups, or R p5 is a fluoro group and R p6 is a trifluoromethyl group, which is preferable.

[0113] n1 is preferably from 0 to 5, more preferably from 0 to 3, still more preferably from 0 to 2, and particularly preferably 0 or 1. n2 is preferably from 0 to 5, more preferably from 0 to 2, still more preferably 0 or 1, and particularly preferably 0. n3 is preferably from 1 to 5, more preferably from 1 to 3, still more preferably 1 or 2. By setting n3 within the above range, the strength of the acid generated from the (B) acid generator can be increased, and as a result, the defect suppression property, LWR performance, and sensitivity of the present composition can be further improved. n1 + n2 + n3 is preferably 2 or more. Also, n1 + n2 + n3 is preferably 10 or less, and more preferably 5 or less.

[0114] In the (B) acid generator, the organic anion preferably has a benzoyloxy group-containing sulfonium anion structure. Specifically, "R p1 -(R p2 ) n1 -" in the above formula (7) is preferably a structure represented by the following formula (7A). In the following formula (7A), specific examples of the monovalent substituent represented by R p7 include the same groups as the examples of the substituent that the ring structure represented by R p1 in the above formula (7) may have.

Chemical formula

[0115] (B) Specific examples of the organic anion contained in the acid generator include, for example, organic anions represented by the following formulae, etc. However, the organic anion contained in the (B) acid generator is not limited to the following structures. [Chemical formula] [Chemical formula] [Chemical formula]

[0116] The onium salt [LB1] is preferably at least one selected from the group consisting of a compound comprising a radiation-sensitive onium cation having the partial structure represented by the above formula (1) and an organic anion, and a compound comprising a radiation-sensitive onium cation having the partial structure represented by the above formula (2) and an organic anion. Specific examples of the onium salt [LB2] include compounds comprising the organic cation represented by the above formula (4) and an organic anion, compounds comprising the organic cation represented by the above formula (5) and an organic anion, and compounds comprising the organic cation represented by the above formula (6) and an organic anion, etc.

[0117] When the (B) acid generator is a low molecular weight compound, the molecular weight of the (B) acid generator is preferably 1000 or less, more preferably 900 or less, still more preferably 800 or less, and even more preferably 600 or less. Also, when the (B) acid generator is a low molecular weight compound, the molecular weight of the (B) acid generator is, for example, 100 or more, and more preferably 150 or more.

[0118] When the (B) acid generator is a polymer, the polymer (hereinafter also referred to as "polymer (PB)") is a polymer having the structural unit (IV). However, the polymer (PB) is distinguished from the (A) polymer in that it does not have the structural unit (I). Specific examples of the polymer (PB) include the following polymers [PB1] and [PB2]. A polymer comprising a radiation-sensitive onium cation having two or more substituents β and an organic anion, and having a structural unit derived from a monomer in which either the radiation-sensitive onium cation or the organic anion contains a group participating in polymerization. [PB2] A polymer comprising another organic cation and an organic anion, and having a structural unit derived from a monomer in which either the other organic cation or the organic anion contains a group participating in polymerization.

[0119] Specific examples of the structural unit (IV) possessed by the polymer (PB) include structural units represented by each of the above formulas (iv-1a) to (iv-9a).

[0120] The polymer (PB) may further have a structural unit different from the structural unit (IV). Examples of such a structural unit include, for example, the structural units exemplified as other structural units in the description of the (A) polymer. The polymer (PB) can be synthesized by a method similar to the method described above as the synthesis method of the (A) polymer.

[0121] Regarding the polymer (PB), the weight average molecular weight (Mw) in terms of polystyrene by GPC is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, and particularly preferably 5,000 or more. Also, the Mw of the polymer (PB) is preferably 50,000 or less, more preferably 30,000 or less, still more preferably 20,000 or less, and particularly preferably 10,000 or less. The ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer (PB) is preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1.7 or less. Also, the Mw / Mn of the polymer (PB) is usually 1 or more, and preferably 1.3 or more.

[0122] As the (B) acid generator in the present composition, among the above, it is preferable to use low molecular compounds (that is, onium salts [LB1] and [LB2]), and it is more preferable to contain the onium salt [LB1].

[0123] The content ratio of the (B) acid generator in the present composition is preferably 1% by mass or more, more preferably 2% by mass or more, and still more preferably 3% by mass or more with respect to 100 parts by mass of the (A) polymer. Further, the content ratio of the (B) acid generator is preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less with respect to 100 parts by mass of the (A) polymer. By setting the content ratio of the (B) acid generator within the above range, it is suitable in that the defect suppressibility, LWR performance, and sensitivity of the present composition can be further improved. As the (B) acid generator, one kind may be used alone, or two or more kinds may be used in combination.

[0124] <(C) Acid diffusion control agent> (C) The acid diffusion control agent is blended into the present composition for the purpose of suppressing the chemical reaction by acid in the non-exposed area by suppressing the diffusion of the acid generated from the (B) acid generator in the resist film upon exposure. By blending the (C) acid diffusion control agent into the present composition, it is suitable in that the lithography characteristics of the present composition can be further improved. Furthermore, it is possible to suppress the line width change of the resist pattern due to the variation in the standing time from exposure to development processing, and a radiation-sensitive composition excellent in process stability can be obtained.

[0125] Examples of the (C) acid diffusion control agent include nitrogen-containing compounds and photo-dissociable bases. As the photo-dissociable base, a compound that generates an acid weaker than the acid generated by the (B) acid generator upon exposure can be used. For example, compounds that generate a weak acid (preferably a carboxylic acid), a sulfonic acid, or a sulfonamide upon exposure can be mentioned. The magnitude of acidity can be evaluated by the acid dissociation constant (pKa). The acid dissociation constant of the acid generated by the photo-dissociable base is usually -3 or more, preferably -1 ≤ pKa ≤ 7, and more preferably 0 ≤ pKa ≤ 5. The (C) acid diffusion control agent is preferably a low molecular weight compound.

[0126] In the case where the composition contains a (B) acid generator and a (C) acid diffusion controller and the (C) acid diffusion controller contains a photo-disintegrating base, the (B) acid generator corresponds to the "first acid generator", and the photo-disintegrating base corresponds to the "second acid generator".

[0127] · Nitrogen-containing compound Examples of the nitrogen-containing compound include a compound represented by the following formula (8) (hereinafter also referred to as "nitrogen-containing compound (8A)"), a compound having two nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (8B)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (8C)"), an amide group-containing compound, a urea compound, a nitrogen-containing heterocyclic compound, a nitrogen-containing compound having an acid dissociable group, and the like.

Chemical formula

[0128] Specific examples of the nitrogen-containing compound include, as the nitrogen-containing compound (8A), for example, monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine and tri-n-pentylamine; aromatic amines such as aniline and 2,6-diisopropylaniline, and the like. Examples of the nitrogen-containing compound (8B) include ethylenediamine, N,N,N',N'-tetramethylethylenediamine, and the like. Examples of the nitrogen-containing compound (8C) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethyl acrylamide, and the like.

[0129] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, and the like. Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea, and the like. Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecane-1-ylcarbonyloxyethyl)morpholine; pyrazine, pyrazole, and the like.

[0130] Examples of the nitrogen-containing compound having an acid dissociable group include N-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-amyloxycarbonyl-4-hydroxypiperidine, and the like.

[0131] Among them, the nitrogen-containing compound as the (C) acid diffusion controller is preferably at least one selected from the group consisting of the nitrogen-containing compound (8A) and the nitrogen-containing heterocyclic compound, more preferably at least one selected from the group consisting of trialkylamines, aromatic amines, and morpholines, and still more preferably at least one selected from the group consisting of tri-n-pentylamine, 2,6-diisopropylaniline, and N-(undecane-1-ylcarbonyloxyethyl)morpholine.

[0132] · Photodecomposable base The photo-dissociable base is preferably a compound that generates an acid upon irradiation with radiation, and this acid does not substantially dissociate the acid-dissociable group in this composition when heated at a temperature of 110 °C for 1 minute. The photo-dissociable base is typically a compound in which the acid generated by exposure does not cause or hardly causes the dissociation reaction of the acid-dissociable group under the use conditions.

[0133] As the photo-dissociable base, an onium salt that generates a carboxylic acid, a sulfonic acid or a sulfonamide upon irradiation with radiation can be preferably used. Preferred specific examples of the photo-dissociable base include onium salt compounds represented by the following formula (9).

Chemical formula

[0134] In the above formula (9), examples of the monovalent organic group having 1 to 30 carbon atoms represented by R 51 include a monovalent hydrocarbon group having 1 to 30 carbon atoms, a monovalent group γ having 1 to 30 carbon atoms containing a divalent heteroatom-containing group between carbon-carbon bonds or at the terminal on the bond side of the hydrocarbon group, a hydrocarbon group, or a monovalent group in which at least one hydrogen atom of the monovalent group γ is substituted with a monovalent heteroatom-containing group. Specific examples thereof include, for example, R 31 , R 32 and R 33 of the above formula (4).Examples of the monovalent organic group represented by include groups similar to the groups exemplified. R 51 The monovalent organic group having 1 to 30 carbon atoms represented by is preferably, among others, a monovalent group having a substituted or unsubstituted aromatic ring. R 51 The group represented by may have the partial structure represented by the above formula (7A).

[0135] R 52 Examples of the monovalent organic group having 1 to 30 carbon atoms represented by include a substituted or unsubstituted alkyl group and a substituted or unsubstituted cycloalkyl group. Examples of the substituent in the substituted alkyl group include a fluoro group and the like. Examples of the substituent in the substituted cycloalkyl group include an alkyl group having 1 to 10 carbon atoms, a fluoro group, an iodine group, and the like.

[0136] Z + The radiation-sensitive onium cation represented by is preferably the organic cation represented by the above formula (Y-1) or formula (Y-2). Z + The radiation-sensitive onium cation represented by may have a specific cation structure [X], or may be another organic cation. Specific examples of the photo-dissociable base include, for example, the following onium salts [C1] and [C2]. [C1] An onium salt composed of a radiation-sensitive onium cation having two or more substituent βs and an organic anion. [C2] An onium salt composed of another organic cation and an organic anion.

[0137] In the onium salt [C1], examples of the radiation-sensitive onium cation having two or more substituent βs include a radiation-sensitive onium cation having the partial structure represented by the above formula (1) and a radiation-sensitive onium cation having the partial structure represented by the above formula (2). Examples of the other organic cation include the onium cation represented by the above formula (4), the onium cation represented by the above formula (5), and the onium cation represented by the above formula (6).

[0138] The organic anion of the photo-dissociable base preferably has a carboxylate anion structure or a sulfonate anion structure. Specific examples of the organic anion include, for example, the organic anions represented by the following formulas. However, the organic anion of the photo-dissociable base is not limited to the following structures. [Chemical formula] [Chemical formula]

[0139] Specific examples of the onium salt [C1] include, for example, compounds composed of a radiation-sensitive onium cation having the partial structure represented by the above formula (1) and a carboxylate anion or a sulfonate anion, and compounds composed of a radiation-sensitive onium cation having the partial structure represented by the above formula (2) and a carboxylate anion or a sulfonate anion. Specific examples of the onium salt [C2] include compounds composed of the organic cation represented by the above formula (4) and a carboxylate anion or a sulfonate anion, compounds composed of the organic cation represented by the above formula (5) and a carboxylate anion or a sulfonate anion, and compounds composed of the organic cation represented by the above formula (6) and a carboxylate anion or a sulfonate anion.

[0140] (C) The molecular weight of the acid diffusion controller is preferably 1000 or less, more preferably 900 or less, still more preferably 800 or less, and even more preferably 600 or less. Also, the molecular weight of the (C) acid diffusion controller is, for example, 100 or more, and preferably 150 or more.

[0141] When the composition contains (C) an acid diffusion control agent, the content ratio of the (C) acid diffusion control agent in the composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and still more preferably 3% by mass or more with respect to 100 parts by mass of the (A) polymer. Further, the content ratio of the (C) acid diffusion control agent is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less with respect to 100 parts by mass of the (A) polymer. By setting the content ratio of the (C) acid diffusion control agent within the above range, it is suitable in that the LWR performance of the composition can be further improved. As the (C) acid diffusion control agent, one kind may be used alone, or two or more kinds may be used in combination.

[0142] The ratio of the acid generating compound contained in the composition (that is, the total ratio of the (B) acid generator and the (C) acid diffusion control agent) is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, and even more preferably 5% by mass or more with respect to the total amount of the solid content contained in the composition. Further, the ratio of the acid generating compound is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and even more preferably 8% by mass or more with respect to the total amount of the solid content contained in the composition. By setting the content ratio of the acid generating compound within the above range, it is suitable in that the lithography characteristics such as the LWR performance and CDU performance of the composition can be improved.

[0143] In the composition, the ratio of the specific cation structure [X] among the radiation-sensitive onium cations possessed by the acid generating compound is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 50 mol% or more, and even more preferably 70 mol% or more. By setting the ratio of the specific cation structure [X] to the radiation-sensitive onium cation possessed by the acid generating compound within the above range, it is suitable in that the effects of improving the sensitivity, CDU performance, and development residue suppression of the composition can be sufficiently obtained.

[0144] <(D) solvent> (D) The solvent is not particularly limited as long as it can dissolve or disperse (A) the polymer, (B) the acid generator, and optionally contained (C) acid diffusion controller, etc. Examples of (D) the solvent include alcohols, ethers, ketones, amides, esters, hydrocarbons, etc.

[0145] Examples of alcohols include aliphatic monoalcohols having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohols having 3 to 18 carbon atoms such as cyclohexanol; polyhydric alcohols having 2 to 18 carbon atoms such as 1,2-propylene glycol; and polyhydric alcohol partial ethers having 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.

[0146] Examples of ketones include chain 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, diacetone alcohol, etc. Examples of amides include cyclic amides such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0147] Examples of the 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; polyvalent carboxylic acid diesters such as diethyl oxalate; carbonates such as dimethyl carbonate and diethyl carbonate; cyclic esters such as γ-butyrolactone and the like. Examples of the hydrocarbons include aliphatic hydrocarbons having 5 to 12 carbon atoms such as n-pentane and n-hexane; aromatic hydrocarbons having 6 to 16 carbon atoms such as toluene and xylene and the like.

[0148] (D) As the solvent, it is preferable to contain at least one selected from the group consisting of esters and ketones, more preferably to contain at least one selected from the group consisting of polyhydric alcohol partial ether carboxylates and cyclic ketones, and still more preferably to contain at least one of propylene glycol monomethyl ether acetate, ethyl lactate and cyclohexanone. As the solvent (D), one kind or two or more kinds can be used.

[0149] <(E) High fluorine-containing polymer> (E) The high fluorine-containing polymer (hereinafter, also simply referred to as “(E) polymer”) is a polymer having a higher mass content rate of fluorine atoms than the (A) polymer. The (E) polymer is contained in the present composition as a water repellent additive, for example. The (E) polymer is distinguished from the (A) polymer in that it does not have the structural unit (I).

[0150] (E) The fluorine atom content rate of the polymer is not particularly limited as long as it is higher than that of the (A) polymer, but is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 4% by mass or more, and particularly preferably 7% by mass or more. Further, the fluorine atom content rate of the (E) polymer is preferably 60% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. The fluorine atom content rate (% by mass) of the polymer is 13The structure of the polymer can be determined by 13C-NMR spectrum measurement or the like, and can be calculated from the structure.

[0151] (E) Examples of the structural unit contained in the polymer include the following structural unit (Ea) and structural unit (Eb). The polymer (E) may contain one or more of each of the structural unit (Ea) and the structural unit (Eb).

[0152] [Structural unit (Ea)] The structural unit (Ea) is a structural unit represented by the following formula (11a). By having the structural unit (Ea), the polymer (E) can adjust the fluorine atom content. [Chemical formula] (In formula (11a), R C 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, -CO-O-, -SO2-O-NH-, -CO-NH- or -O-CO-NH-. R E is a monovalent fluorinated linear hydrocarbon group having 1 to 6 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 4 to 20 carbon atoms.

[0153] Examples of the monovalent fluorinated linear hydrocarbon group having 1 to 6 carbon atoms represented by R E include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a perfluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a perfluoro n-propyl group, a perfluoroisopropyl group, a perfluoro n-butyl group, a perfluoroisobutyl group, a perfluoro t-butyl group, a 2,2,3,3,4,4,5,5-octafluoropentyl group, a perfluorohexyl group and the like.

[0154] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R EExamples of the monovalent fluorinated alicyclic hydrocarbon group represented by are, for example, a monofluorocyclopentyl group, a difluorocyclopentyl group, a perfluorocyclopentyl group, a monofluorocyclohexyl group, a difluorocyclohexyl group, a perfluorocyclohexylmethyl group, a fluoronorbornil group, a fluoroadamantyl group, a fluorobornyl group, a fluoroisobornyl group, a fluorotricyclodecyl group, a fluorotetracyclodecyl group, and the like.

[0155] Examples of the monomer that provides the structural unit (Ea) include, for example, (meth)acrylate having a fluorinated chain hydrocarbon group, (meth)acrylate having a fluorinated alicyclic hydrocarbon group, and the like. Specific examples thereof include, as the (meth)acrylate having a fluorinated chain hydrocarbon group, for example, a linear partially fluorinated alkyl (meth)acrylate such as 2,2,2-trifluoroethyl (meth)acrylate; a branched-chain partially fluorinated alkyl (meth)acrylate such as 1,1,1,3,3,3-hexafluoroisopropyl (meth)acrylate; a linear perfluoroalkyl (meth)acrylate such as perfluoroethyl (meth)acrylate; a branched-chain perfluoroalkyl (meth)acrylate such as perfluoroisopropyl (meth)acrylate, and the like. Examples of the (meth)acrylate having a fluorinated alicyclic hydrocarbon group include, for example, (meth)acrylate having a monocyclic fluorinated alicyclic saturated hydrocarbon group such as perfluorocyclohexylmethyl (meth)acrylate, monofluorocyclopentyl (meth)acrylate, perfluorocyclopentyl (meth)acrylate; (meth)acrylate having a polycyclic fluorinated alicyclic saturated hydrocarbon group such as fluoronorbornil (meth)acrylate, and the like.

[0156] (E) When the polymer has the structural unit (Ea), the content ratio of the structural unit (Ea) is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 20 mol% or more with respect to all the structural units constituting the (E) polymer.

[0157] [Structural unit (Eb)] The structural unit (Eb) is a structural unit represented by the following formula (11b). Since the (E) polymer has the structural unit (Eb), the hydrophobicity is increased, and thus the dynamic contact angle of the surface of the resist film formed from this composition can be further improved. [Chemical formula] (In formula (11b), R F is a hydrogen atom, a fluoro group, a methyl group or a trifluoromethyl group. R 59 is a (s + 1)-valent hydrocarbon group having 1 to 20 carbon atoms, or a group in which an oxygen atom, a sulfur atom, -NR'-, a carbonyl group, -CO-O- or -CO-NH- is bonded to the terminal on the R 60 side of the hydrocarbon group. R' is a hydrogen atom or a monovalent organic group. R 60 is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms or a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. X 12 is a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. A 11 is an oxygen atom, -NR"-, -CO-O-*, or -SO2-O-*. R" is a hydrogen atom or a monovalent organic group. * indicates the bonding site to R 61 . R 61 is a hydrogen atom or a monovalent organic group. s is an integer of 1 to 3. However, when s is 2 or 3, a plurality of R 60 , X 12 , A 11 and R 61 are each the same or different.)

[0158] R 61 When is a hydrogen atom, it is preferable in that the solubility of the (E) polymer in an alkaline developer can be improved. R61 Examples of the monovalent organic group represented by [Chemical Formula 1] include an acid dissociable group, an alkali dissociable group, or a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, and the like.

[0159] (E) When the polymer has the structural unit (Eb), the content ratio of the structural unit (Eb) is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 20 mol% or more with respect to all the structural units constituting the (E) polymer.

[0160] (E) In addition to the structural unit (Ea) and the structural unit (Eb), the polymer may contain a structural unit containing an acid dissociable group and different from the structural unit (Ea) and the structural unit (Eb) (hereinafter also referred to as "structural unit (Ec)"). By having the structural unit (Ec) in the (E) polymer, the shape of the resulting resist pattern becomes better. Examples of the structural unit (Ec) include the structural unit (I) and the structural unit (III) described in the (A) polymer.

[0161] (E) When the polymer has the structural unit (Ec), the content ratio of the structural unit (Ec) is preferably 5 mol% or more, more preferably 25 mol% or more, and still more preferably 50 mol% or more with respect to all the structural units constituting the (E) polymer. Also, the content ratio of the structural unit (Ec) is preferably 90 mol% or less, more preferably 80 mol% or less, and still more preferably 70 mol% or less with respect to all the structural units constituting the (E) polymer.

[0162] The Mw of the (E) polymer by GPC is preferably 1,000 or more, more preferably 3,000 or more, and still more preferably 4,000 or more. Also, the Mw of the (E) polymer is preferably 50,000 or less, more preferably 30,000 or less, and still more preferably 20,000 or less. The molecular weight distribution (Mw / Mn) represented by the ratio of Mn to Mw of the (E) polymer by GPC is usually 1 or more, and preferably 1.2 or more. Also, Mw / Mn is preferably 5 or less, more preferably 3 or less.

[0163] When the composition contains the (E) polymer, the content ratio of the (E) polymer in the composition is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more with respect to 100 parts by mass of the (A) polymer. Further, the content ratio of the (E) polymer is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 7 parts by mass or less with respect to 100 parts by mass of the (A) polymer. Note that the composition may contain the (E) polymer alone or in combination of two or more kinds.

[0164] <Other optional components> The composition may further contain components different from the above-mentioned (A) polymer, (B) acid generator, (C) acid diffusion controller, (D) solvent, and (E) highly fluorine-containing polymer (hereinafter also referred to as "other optional components"). Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds (for example, 1-adamantanecarboxylic acid, 2-adamantanone, t-butyl deoxycholate, etc.), sensitizers, uneven distribution promoters, and the like. The content ratio of the other optional components in the composition can be appropriately selected according to each component within a range not impairing the effects of the present disclosure.

[0165] ≪Method for producing radiation-sensitive composition≫ The composition can be produced, for example, by mixing components such as (C) acid diffusion controller and (D) solvent in a desired ratio in addition to the (A) polymer and (B) acid generator, and filtering the obtained mixture, preferably using a filter (for example, a filter having a pore diameter of about 0.2 μm). The solid content concentration of the composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 1% by mass or more. Also, the solid content concentration of the composition is preferably 50% by mass or less, more preferably 20% by mass or less, and still more preferably 5% by mass or less. Setting the solid content concentration of the composition within the above range is suitable in that it can improve the coatability and the shape of the resist pattern.

[0166] The present composition thus obtained can be used as a positive pattern-forming composition for forming a pattern using an alkaline developer, or can also be used as a negative pattern-forming composition using a developer containing an organic solvent.

[0167] ≪Resist Pattern Forming Method≫ The resist pattern forming method in the present disclosure includes a step of applying the present composition onto one surface of a substrate (hereinafter, also referred to as the "coating step"), a step of exposing the resist film obtained by the above coating step (hereinafter, also referred to as the "exposure step"), and a step of developing the exposed resist film (hereinafter, also referred to as the "development step"). Examples of the pattern formed by the resist pattern of the present disclosure include a line and space pattern, a hole pattern, and the like. In the resist pattern forming method of the present disclosure, since a resist film is formed using the present composition, a resist pattern having good sensitivity, small CDU, and little development residue can be formed. Hereinafter, each step will be described.

[0168] [Coating Step] In this step, a resist film is formed on the substrate by applying the present composition onto one surface of the substrate. As the substrate for forming the resist film, conventionally known ones can be used, for example, a silicon wafer, silicon dioxide, a wafer coated with aluminum, and the like. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Unexamined Patent Application Publication No. 59-93448, etc. may be formed on the substrate and used. Examples of the coating method of the present composition include spin coating, casting, roll coating, and the like. After coating, prebaking (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. Also, the temperature of PB is preferably 140°C or lower, more preferably 120°C or lower. The time of PB is preferably 5 seconds or longer, more preferably 10 seconds or longer. Also, the time of PB is preferably 600 seconds or shorter, more preferably 300 seconds or shorter. The average thickness of the formed resist film is preferably 10 to 1,000 nm, more preferably 20 to 500 nm.

[0169] [Lithography process] In this process, the resist film obtained by the above coating process is exposed. This exposure is performed by irradiating the resist film with radiation through a photomask and, in some cases, through an immersion medium such as water. Examples of the radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and γ-rays; charged particle beams such as electron beams and α-rays. Among these, the radiation for irradiating 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, still more preferably ArF excimer laser light, EUV, or an electron beam, even more preferably EUV or an electron beam, and particularly preferably EUV.

[0170] After the above exposure, it is preferable to perform post-exposure baking (PEB). It is considered that this PEB can promote the dissociation of the acid-dissociable group by the acid generated from the acid-generating compound in the exposed portion of the resist film. Thereby, the difference in solubility in the developer between the exposed portion and the unexposed portion can be increased. The temperature of the PEB is preferably 50°C or higher, more preferably 80°C or higher. Also, the temperature of the PEB is preferably 180°C or lower, more preferably 130°C or lower. The time of the PEB is preferably 5 seconds or longer, more preferably 10 seconds or longer. Also, the time of the PEB is preferably 600 seconds or shorter, more preferably 300 seconds or shorter.

[0171] [Development process] In this process, the exposed resist film is developed. Thereby, a desired resist pattern can be formed. After development, it is common to wash with a rinse solution such as water or alcohol and then dry. The development method in the development process may be alkali development or organic solvent development.

[0172] In the case of alkali development, examples of the developer used for development include, for example, an aqueous alkali solution in which at least one of alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved. Among these, an aqueous TMAH solution is preferred, and a 2.38 mass% aqueous TMAH solution is more preferred.

[0173] In the case of organic solvent development, examples of the developer include one or more of various organic solvents (for example, hydrocarbons, ethers, esters, ketones, alcohols, etc.). Specific examples of the organic solvent used as the developer include, for example, the solvents listed as the (D) solvent in the description of this composition. Among these, esters and ketones are preferred as the developer for organic solvent development. As the esters, acetic acid esters are preferred, and n-butyl acetate is more preferred. As the ketones, chain ketones are preferred, and 2-heptanone is more preferred. In the developer, the content of the organic solvent is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and particularly preferably 99 mass% or more. Examples of components other than the organic solvent in the developer include water, silicone oil, etc.

[0174] Examples of the development method include, for example, a method of immersing the substrate in a tank filled with the developer for a certain period of time (dip method), a method of developing by raising the developer on the substrate surface by surface tension and allowing it to stand for a certain period of time (paddle method), a method of spraying the developer on the substrate surface (spray method), a method of continuously discharging the developer while scanning a developer discharge nozzle at a certain speed on a substrate rotating at a certain speed (dynamic dispense method), etc.

Examples

[0175] Hereinafter, the present disclosure will be specifically described based on examples, but the present disclosure is not limited to these examples. The measurement methods for each physical property value are shown below.

[0176] [Weight-average molecular weight and number-average molecular weight] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer were measured by gel permeation chromatography (GPC) using Tosoh's GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions. Eluent: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Column temperature: 40 °C Detector: Differential refractometer Standard substance: Monodisperse polystyrene 1 1H-NMR] 1 1H-NMR analysis was performed using a nuclear magnetic resonance apparatus ("JNM-ECZS400" manufactured by JEOL Ltd.).

[0177] The structures of the radiation-sensitive acid generator (PAG), acid diffusion controller, and high-fluorine-containing resin used in the preparation of the radiation-sensitive resin composition are shown below.

[0178] [Radiation-sensitive acid generator (PAG)] The structures of the radiation-sensitive acid generators (PAG1 to PAG9) used in the following examples are as follows. For PAG1 to PAG9, they were synthesized by ion exchange between an ammonium salt of sulfonic acid that provides an organic acid anion moiety and sulfonium chloride or iodonium chloride that provides an onium cation moiety, respectively. Note that PAG1 to PAG3 and PAG5 to PAG8 are radiation-sensitive acid generators having a specific cation structure [X]. For example, the number of substituents β of PAG1 is 2, and the number of substituents β of PAG8 is 3. ​[Chemical] [Chemical]

[0179] [Acid diffusion control agent] The structures of the acid diffusion control agents (Q-1 to Q-7) used in the following examples are as follows. Note that Q-2 and Q-4 are acid diffusion control agents having a specific cation structure [X]. [Chemical] [Chemical]

[0180] [High fluorine-containing resin] The structure and physical properties of the high fluorine-containing resin (F-1) used in the following example are as follows. F-1: Mw = 8,900, Mw / Mn = 2.0 [Chemical]

[0181] [Synthesis of base resins (P-1 to P-5)] Each monomer was combined and copolymerized under a tetrahydrofuran (THF) solvent. It was crystallized in methanol, and after repeated washing with hexane, it was isolated and dried. As a result, polymers P-1 to P-5 were obtained as polymers having the following compositions (molar ratios) (referred to as "base resins"). The composition of the obtained base resins was 1 confirmed by 1H-NMR, and Mw and dispersity (Mw / Mn) were confirmed by GPC (solvent: THF, standard: polystyrene). Polymer P-1: Mw = 7,900, Mw / Mn = 1.8 Polymer P-2: Mw = 7,800, Mw / Mn = 1.8 Polymer P-3: Mw = 8,200, Mw / Mn = 1.8 Polymer P-4: Mw = 8,100, Mw / Mn = 1.8 Polymer P-5: Mw = 9,400, Mw / Mn = 1.7 Note that P-2 and P-3 are polymers having a specific cation structure [X].

[0182] (Composition of the base resin)

Chemical formula

Chemical formula

[0183] [Examples 1 to 15, Comparative Examples 1 to 3] 1. Preparation of the radiation-sensitive resin composition Each component was dissolved in a solvent in which 100 ppm of FC-4430 manufactured by 3M was dissolved as a surfactant, according to the composition shown in Table 1. The resulting solution was filtered through a 0.2 μm size membrane filter to prepare a radiation-sensitive resin composition.

[0184] 2. Evaluation of sensitivity by EUV exposure On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), a composition for forming a lower layer film ("ARC66" from Brewer Science, Inc.) was coated, and then heated at 205°C for 60 seconds to form a lower layer film with an average thickness of 105 nm. On this lower layer film, each radiation-sensitive resin composition shown in Table 1 was coated using the above spin coater, and PB was performed at 130°C for 60 seconds. Then, by cooling at 23°C for 30 seconds, a resist film with an average thickness of 55 nm was formed. This resist film was exposed using an EUV scanner ("NXE3300" from ASML (NA 0.33, σ 0.9 / 0.6, quadrupole illumination, mask with a hole pattern having a wafer-level dimension of pitch 46 nm and +20% bias)). PEB was performed on a hot plate at 120°C for 60 seconds, and development was performed for 30 seconds with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) to form a resist pattern of 23-nm holes and 46-nm pitch. The exposure dose for forming this resist pattern of 23-nm holes and 46-nm pitch was defined as the optimum exposure dose (Eop), and the optimum exposure dose was defined as the sensitivity (mJ / cm 2 ).

[0185] 3. CDU Evaluation Irradiating with the exposure dose of Eop obtained above, and performing the same operations as in 2. above to form a resist pattern of 23-nm holes and 46-nm pitch. The formed resist pattern was observed from the top of the pattern using a scanning electron microscope ("CG-5000" from Hitachi High-Technologies Corporation). The hole diameters were measured at 16 points within a range of 500 nm in diameter to obtain an average value, and by repeating this, the average value was measured at a total of 500 points at arbitrary points. The 3-sigma value was obtained from the distribution of the measured values, and the obtained 3-sigma value was used as the evaluation value (nm) of the CDU performance. The CDU performance is better as the evaluation value is smaller, indicating less variation in the hole diameter over a long period. The results are shown in Table 1.

[0186] 4. Evaluation of Development Residue Up to the operation of forming a resist film with an average thickness of 55 nm, a wafer with a resist film was fabricated by performing the same operations as in 2. above. Next, the entire surface of the resist film was exposed with the optimum exposure dose using an EUV scanner, and then PEB was performed on a hot plate at 120 °C for 60 seconds. Subsequently, development was carried out for 30 seconds with a 2.38 mass% TMAH aqueous solution, rinsed with pure water for 30 seconds, and dried. In this way, a wafer for development residue evaluation was fabricated. This evaluation wafer was observed with a defect inspection device COMPLUS (manufactured by AMAT), and the presence or absence of residue defects was confirmed using a defect review SEM RS5500 (manufactured by Hitachi High-Technologies Corporation), and the number of residue defects was counted. Evaluation was performed using the following criteria according to the counted number of residue defects. A: 5 or less B: 6 - 10 C: 11 - 20 D: 21 or more

[0187]

Table 1

[0188] In Table 1, the details of the solvents are as follows. PGMEA (propylene glycol monomethyl ether acetate) GBL (γ-butyrolactone) CHN (cyclohexanone) PGME (propylene glycol monomethyl ether) DAA (diacetone alcohol) EL (ethyl lactate)

[0189] As a result of evaluating the resist patterns formed by EUV exposure, the radiation-sensitive resin compositions of Examples 1 to 15 had good sensitivity and CDU performance, and also had few development residues. Among them, as the specific cation structure [X], the radiation-sensitive resin compositions of Examples 3 to 15 containing a radiation-sensitive onium cation in which the total number of fluoro groups and fluoroalkyl groups is 3 or more had development residues of 10 or less and were evaluated as "A" or "B". Further, the effect of reducing development residues was particularly excellent when the total number of fluoro groups and fluoroalkyl groups in the specific cation structure [X] was 4 or more.

[0190] On the other hand, Comparative Examples 1 and 2 containing the structural unit (I) but not containing the specific cation structure [X] had lower sensitivity and more development residues than Examples 1 to 15. Comparative Example 3 containing the specific cation structure [X] but not containing the structural unit (I) had lower sensitivity than Examples 1 to 15.

[0191] According to the radiation-sensitive resin composition and the resist pattern forming method described above, a resist pattern having good sensitivity to exposure light, excellent CDU performance, and development residue suppressing properties can be formed. Therefore, these can be suitably used in the processing process of semiconductor devices and the like, which are expected to be further miniaturized in the future.

Claims

1. (A) a polymer containing a structural unit represented by the following formula (i); a photoacid generator having a photo-sensitive onium cation structure and an organic anion structure (however, excluding the above-mentioned (A) polymer); containing the following requirements [K1] and [K2]; [K1] The (A) polymer has a photo-sensitive onium cation structure [X] having at least two substituents β selected from the group consisting of a fluoroalkyl group and a fluoro group (however, excluding the fluoro group in the fluoroalkyl group). [K2] The photoacid generator contains a compound having the photo-sensitive onium cation structure [X]. satisfying at least requirement [K1] among them, The (A) polymer contains a structural unit having the photo-sensitive onium cation structure [X] and an organic anion, and is a radiation-sensitive composition. 【Chemical 1】 (In formula (i), R ａ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. R ２ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. n is an integer of 0 to 16. When n is 1, R ３ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. When n is 2 or more, a plurality of R ３ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a plurality of R ３ are combined with each other to represent an alicyclic structure having 3 to 20 ring members together with the carbon atom or carbon chain to which they are attached.)

2. The radiation-sensitive composition according to claim 1, wherein the radiation-sensitive onium cation structure [X] has a sulfonium cation structure or an iodonium cation structure.

3. The radiation-sensitive onium cation structure [X] has one or more aromatic rings Z bonded to a sulfonium cation or an iodonium cation, and one or more of the aromatic rings Z have a structure in which two or more of the substituents β are bonded to the same aromatic ring, or has two or more of the aromatic rings Z, and has a structure in which one or more of the substituents β are bonded to each of two or more different aromatic rings. The radiation-sensitive composition according to claim 2.

4. The radiation-sensitive composition according to any one of claims 1 to 3, wherein at least one of the (A) polymer and a polymer different from the (A) polymer contains a structural unit having a hydroxyl group bonded to an aromatic ring.

5. The radiation-sensitive composition according to any one of claims 1 to 4, which is used for forming a resist pattern by exposure to extreme ultraviolet light.

6. The radiation-sensitive composition according to any one of claims 1 to 5, which contains a compound having the radiation-sensitive onium cation structure [X] as a compound different from the (A) polymer.

7. The radiation-sensitive composition according to any one of claims 1 to 6, wherein the photoacid generator contains a first photoacid generator and a second photoacid generator that generates an acid weaker than the acid generated by the first photoacid generator upon exposure.

8. A step of forming a resist film on a substrate using the radiation-sensitive composition according to any one of claims 1 to 7; A step of exposing the resist film; A step of developing the exposed resist film; A resist pattern forming method comprising:

9. The resist pattern forming method according to claim 8, wherein the resist film is exposed using extreme ultraviolet rays.

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