Radiation-sensitive composition, resist pattern formation method, polymer, monomer, and method for synthesizing monomer

Abstract

This radiation-sensitive composition comprises: a polymer that has a structural unit (I) represented by formula (1) and a structural unit (II) containing a phenolic hydroxyl group; and an organic solvent.

Description

Radiation-sensitive composition, method for forming a resist pattern, polymer, monomer, and method for synthesizing the monomer

[0001] The present invention relates to a radiation-sensitive composition, a method for forming a resist pattern, a polymer, a monomer, and a method for synthesizing the monomer.

[0002] Radiation-sensitive compositions used in microfabrication by lithography generate an acid in exposed areas when irradiated with radiation such as far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm), electromagnetic waves such as extreme ultraviolet rays (EUV, wavelength 13.5 nm), or charged particle rays such as electron beams, and a chemical reaction initiated by this acid causes a difference in the dissolution rate in a developer between exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] Radiation-sensitive compositions are required to have good sensitivity to radiation such as extreme ultraviolet rays and electron beams, as well as excellent LWR (Line Width Roughness). Furthermore, as resist patterns become finer, the impact of even slight variations in exposure and development conditions on the shape of the resist pattern and the occurrence of defects becomes increasingly significant. Radiation-sensitive compositions with a wide process window (process latitude) that can absorb such slight variations in process conditions are also required.

[0004] In response to these requirements, the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive compositions have been investigated, and combinations thereof have also been investigated in detail (see JP-A-2010-134279, JP-A-2014-224984, JP-A-2016-047815, and JP-A-2021-009357).

[0005] JP 2010-134279 A JP 2014-224984 A JP 2016-047815 A JP 2021-009357 A

[0006] As resist patterns become finer, the level of performance required is becoming higher and higher, and there is a demand for radiation-sensitive compositions that satisfy these requirements.

[0007] The present invention has been made in light of the above-mentioned circumstances, and an object of the present invention is to provide a radiation-sensitive composition and a method for forming a resist pattern that are excellent in sensitivity and LWR and have a wide process window. Another object of the present invention is to provide a polymer that is suitable as a component of the radiation-sensitive composition. A further object of the present invention is to provide a monomer that is suitable for synthesizing the polymer. A further object of the present invention is to provide a method for synthesizing the monomer.

[0008] The invention made to solve the above-mentioned problems is a radiation-sensitive composition containing a polymer having a structural unit (I) represented by the following formula (1) and a structural unit (II) containing a phenolic hydroxyl group, and an organic solvent: (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ３ is a substituted or unsubstituted (n+1)-valent hydrocarbon group. L is a single bond or a divalent linking group. J is *-COO- or -O-. * indicates the bonding site with L. R ４ is an acid-dissociable group. n is an integer of 1 to 5. When n is 2 or more, multiple Ls may be the same or different, multiple Js may be the same or different, and multiple Rs may be the same or different. ４ are the same or different.)

[0009] Another invention made to solve the above-mentioned problems is a method for forming a resist pattern, comprising the steps of: applying the radiation-sensitive composition described above directly or indirectly to a substrate; exposing the resist film formed by the application; and developing the exposed resist film.

[0010] Still another invention made to solve the above problems is a polymer having a structural unit (I) represented by the following formula (1) and a structural unit (II) containing a phenolic hydroxyl group. (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ３ is a substituted or unsubstituted (n+1)-valent hydrocarbon group. L is a single bond or a divalent linking group. J is *-COO- or -O-. * indicates the bonding site with L. R ４ is an acid-dissociable group. n is an integer of 1 to 5. When n is 2 or more, multiple Ls may be the same or different, multiple Js may be the same or different, and multiple Rs may be the same or different. ４ are the same or different.)

[0011] Yet another invention made to solve the above problems is a monomer represented by the following formula (m1): (In formula (m1), R ｍ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ｍ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ｍ３ is a substituted or unsubstituted (n+1)-valent aromatic hydrocarbon group. ｍ is a single bond or a divalent linking group. ｍ is *-COO- or -O-. ｍ The binding site with R ｍ４ is an acid-dissociable group having 5 to 12 carbon atoms. ｍ is an integer from 1 to 5. ｍ If there are two or more L ｍ are the same or different, and multiple J ｍ are the same or different, and multiple R ｍ４ are the same or different.)

[0012] Yet another invention made to solve the above problems is a method for synthesizing a monomer represented by the above formula (m1) which is any one of the following 1. to 4. 1. R ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ - (L ｍ -COOH)n ｍ and a carboxylic acid compound represented by R ｍ４ 2. A method of condensing with an alcohol compound represented by —OH.ｍ１ -C(=CH ２ )-R ｍ２ A carboxylic acid compound represented by -COOH and H ２ N-R ｍ３ - (L ｍ -J ｍ -R ｍ４ ) n ｍ 3. A method of condensing with an amine compound represented by R ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ Alcohol compounds represented by -OH and Hal-L ｍ -J ｍ -R ｍ４ (Hal is a halogen atom). ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ A carboxylic acid compound represented by —COOH and Hal-L ｍ -J ｍ -R ｍ４ (Hal is a halogen atom).

[0013] The radiation-sensitive composition of the present invention has excellent sensitivity and LWR, and a wide process window. According to the method for forming a resist pattern of the present invention, a resist pattern having excellent sensitivity and LWR and a wide process window can be formed. The polymer of the present invention is suitable as a base resin contained in the radiation-sensitive composition. The monomer of the present invention is suitable as a monomer for synthesizing the polymer contained in the radiation-sensitive composition. According to the method for synthesizing a monomer of the present invention, the monomer can be suitably synthesized. Therefore, these can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

[0014] The radiation-sensitive composition, the method for forming a resist pattern, the polymer, the monomer, and the method for synthesizing the monomer of the present invention will be described in detail below.

[0015] The upper and lower limits can be any combination of the disclosed numerical values. When a numerical range is indicated using the symbol "to", it means that the numerical range includes the upper and lower limit numerical values. For example, "1 to 20 carbon atoms" means "1 to 20 carbon atoms inclusive."

[0016] <Radiation-Sensitive Composition> The radiation-sensitive composition contains a polymer (hereinafter also referred to as “polymer [A]”) having a structural unit (I) represented by formula (1) described below and a structural unit (II) containing a phenolic hydroxyl group, and an organic solvent (hereinafter “organic solvent [D]”).

[0017] The radiation-sensitive composition has the above-described structure, which provides the effects of excellent sensitivity and LWR and a wide process window. The reason for this is not entirely clear, but is presumed to be, for example, as follows: The structural unit (I) contains an amide bond (-CONH-), which is thought to control the diffusion of acid generated from the polymer [A], thereby improving the LWR and process window. Furthermore, the structural unit (II) is thought to promote acid generation, thereby improving the sensitivity. The radiation-sensitive composition has the above-described structure, which combines the above-described effects to achieve a good balance between sensitivity, LWR, and a wide process window.

[0018] The radiation-sensitive composition typically contains a component that generates an acid under the action of radiation (hereinafter also referred to as a "radiation-sensitive acid-generating component"). Examples of the radiation-sensitive acid-generating component include the polymer [A] itself when the polymer [A] has a structural unit containing a group that generates an acid under the action of radiation, and a component other than the polymer [A] is a radiation-sensitive acid generator (hereinafter also referred to as an "acid generator [B]"). The radiation-sensitive composition may contain an acid diffusion controller (hereinafter also referred to as an "acid diffusion controller [C]"). The radiation-sensitive composition can contain other optional components within a range that does not impair the effects of the present invention.

[0019] The radiation-sensitive composition can be prepared, for example, by mixing the polymer (A) and the organic solvent (D), and, if necessary, the acid generator (B), the acid diffusion controller (C), and other optional components in a predetermined ratio, and filtering the resulting mixture through a membrane filter having a pore size of 0.2 μm or less.

[0020] Each component contained in the radiation-sensitive composition will be described below.

[0021] <Polymer [A]> The polymer [A] is a polymer having a structural unit (I) represented by the formula (1) described below and a structural unit (II) containing a phenolic hydroxyl group.

[0022] The radiation-sensitive composition may contain one or more types of polymer (A).

[0023] The polymer (A) may further have other structural units (hereinafter simply referred to as "other structural units") other than the structural units (I) and (II). The polymer (A) may have one or more types of each structural unit.

[0024] The other structural units are structural units other than the structural units (I) and (II) described above. Examples of the other structural units include a structural unit containing an acid-dissociable group different from the structural unit (I) (hereinafter also referred to as "structural unit (III)"), a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof (hereinafter also referred to as "structural unit (IV)"), and a structural unit containing a group that generates an acid when exposed to radiation (hereinafter also referred to as "structural unit (V)").

[0025] In this specification, the term "structural unit" refers to one of the repeating units obtained by polymerizing a monomer, and is composed of a portion that constitutes a main chain and a side chain. The term "main chain" refers to the longest atomic chain that constitutes a polymer. The term "side chain" refers to an atomic chain other than the main chain that constitutes a polymer.

[0026] The lower limit of the content of the polymer (A) in the radiation-sensitive composition is preferably 50% by mass, more preferably 70% by mass, and even more preferably 80% by mass, based on all components other than the organic solvent (D) contained in the radiation-sensitive composition, and the upper limit of the content is preferably 99% by mass, more preferably 95% by mass.

[0027] The lower limit of the weight average molecular weight (Mw) of the polymer [A], as measured by gel permeation chromatography (GPC) in terms of polystyrene, is preferably 1,000, and more preferably 2,000. The upper limit of the Mw is preferably 30,000, more preferably 20,000, even more preferably 15,000, and still more preferably 12,000. By setting the Mw of the polymer [A] within the above range, the coatability of the radiation-sensitive composition can be improved. The Mw of the polymer [A] can be adjusted, for example, by adjusting the type and amount of polymerization initiator used in the synthesis of the polymer [A].

[0028] The upper limit of the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (A) as determined by GPC (hereinafter also referred to as "Mw / Mn") is preferably 2.5, more preferably 2.0, and even more preferably 1.9. The lower limit of the ratio is usually 1.0, preferably 1.1, and more preferably 1.2.

[0029] [Method for measuring Mw and Mn] The Mw and Mn of the polymer in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions: GPC columns: two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column, all manufactured by Tosoh Corporation; column temperature: 40°C; elution solvent: tetrahydrofuran; flow rate: 1.0 mL / min; sample concentration: 1.0 mass%; sample injection amount: 100 μL; detector: differential refractometer; standard material: monodisperse polystyrene.

[0030] The polymer (A) can be synthesized, for example, by polymerizing monomers that provide the respective structural units by a known method.

[0031] Each structural unit contained in the polymer (A) will be described below.

[0032] [Structural Unit (I)] The structural unit (I) is a structural unit represented by the following formula (1). The structural unit (I) is a structural unit containing an acid-dissociable group. The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group or a hydroxy group and dissociates under the action of an acid to give a carboxy group or a hydroxy group. In this specification, when the structural unit (I) also corresponds to the structural unit (II) described below, it is included in the structural unit (I).

[0033] The polymer [A] exhibits a property in which its solubility in a developer changes due to the action of an acid, since the structural unit (I) contains an acid-dissociable group. The acid-dissociable group is dissociated by the action of an acid generated from the radiation-sensitive acid-generating component in response to the action of radiation, resulting in a difference in the solubility of the polymer [A] in a developer between the exposed and unexposed areas, allowing the formation of a resist pattern.

[0034]

[0035] In the above formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ３ is a substituted or unsubstituted (n+1)-valent hydrocarbon group. L is a single bond or a divalent linking group. J is *-COO- or -O-. * indicates the bonding site with L. R ４ is an acid-dissociable group. n is an integer of 1 to 5. When n is 2 or more, multiple Ls may be the same or different, multiple Js may be the same or different, and multiple Rs may be the same or different. ４ are the same or different from each other.

[0036] R １ From the viewpoint of copolymerizability of the monomer that gives the structural unit (I), R is preferably a hydrogen atom or a methyl group. １ is a methyl group, R １ Since the sensitivity and LWR tend to be improved more than when R is a hydrogen atom, １ A methyl group is more preferred as the aryl group.

[0037] R ２ The number of ring members in the aromatic hydrocarbon ring giving the formula (I) is preferably 6 to 30, and more preferably 6 to 20. The "number of ring members" refers to the number of atoms constituting the ring structure, and in the case of a polycycle, it refers to the number of atoms constituting the polycycle. The "polycycle" includes not only fused polycycles in which two rings share two common atoms, but also ring assembly polycycles in which two rings do not share a common atom and are connected by a single bond.

[0038] R ２ Examples of aromatic hydrocarbon rings that give the formula (I) include a benzene ring; condensed polycyclic aromatic hydrocarbon rings such as a naphthalene ring, an anthracene ring, a fluorene ring, a biphenylene ring, a phenanthrene ring, and a pyrene ring; ring-assembly aromatic hydrocarbon rings such as a biphenyl ring, a terphenyl ring, a binaphthalene ring, and a phenylnaphthalene ring; and a 9,10-ethanoanthracene ring. ２ The aromatic hydrocarbon ring that gives the following formula is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

[0039] R ２ Examples of the substituent that may be possessed by the aromatic hydrocarbon ring that gives the formula (I) include a halogeno group such as a fluoro group or an iodo group, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group (a group in which at least one hydrogen atom of an alkyl group is substituted with a fluoro group), an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group.

[0040] R ２ is a single bond, R ２ is a group obtained by removing two hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring, the sensitivity tends to be improved more than when R ２ is preferably a single bond.

[0041] R ３ Examples of the (n+1)-valent hydrocarbon group that satisfies the formula (I) include a group obtained by removing n hydrogen atoms from a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a group obtained by removing n hydrogen atoms from a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a group obtained by removing n hydrogen atoms from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0042] The term "hydrocarbon group" includes "aliphatic hydrocarbon groups" and "aromatic hydrocarbon groups." The term "aliphatic hydrocarbon group" includes "chain hydrocarbon groups" and "alicyclic hydrocarbon groups." From another perspective, the term "aliphatic hydrocarbon group" includes "saturated hydrocarbon groups" and "unsaturated hydrocarbon groups." The term "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed only of a chain structure, and includes both straight-chain hydrocarbon groups and branched-chain hydrocarbon groups. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic ring as a ring structure and does not contain an aromatic ring, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it does not have to be composed only of an alicyclic ring, and may contain a chain structure as part of it. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring as a ring structure. However, it does not have to be composed only of an aromatic ring, and may contain a chain structure or an alicyclic ring as part of it.

[0043] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, isobutyl, and tert-butyl; alkenyl groups such as ethenyl, propenyl, butenyl, and 2-methylprop-1-en-1-yl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0044] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as a cyclopentyl group and a cyclohexyl group; polycyclic alicyclic saturated hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group and a tetracyclododecyl group; monocyclic alicyclic unsaturated hydrocarbon groups such as a cyclopentenyl group and a cyclohexenyl group; and polycyclic alicyclic unsaturated hydrocarbon groups such as a norbornenyl group, a tricyclodecenyl group and a tetracyclododecenyl group.

[0045] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl.

[0046] R３ The (n+1)-valent hydrocarbon group that gives the formula (I) is preferably an (n+1)-valent chain hydrocarbon group or an (n+1)-valent aromatic hydrocarbon group, and more preferably a group in which n hydrogen atoms have been removed from an alkyl group or a group in which n hydrogen atoms have been removed from a phenyl group.

[0047] When n is 1, as described below, that is, R ３ is a divalent group, R ３ As the divalent hydrocarbon group giving the formula (I), an alkanediyl group or an arylene group is preferred, and a methanediyl group or a phenylene group is more preferred. Furthermore, among phenylene groups, an o-phenylene group or a p-phenylene group tends to improve sensitivity more than an m-phenylene group. Furthermore, a p-phenylene group tends to have a wider process window than an o-phenylene group.

[0048] R ３ Examples of the substituent in the (n+1)-valent hydrocarbon group that gives ２ Examples of the substituent that the aromatic hydrocarbon ring may have include the groups exemplified above. The substituent may also be a group that generates an acid when exposed to radiation. Among these, a halogeno group is preferred, and an iodo group is more preferred.

[0049] Examples of the acid generated from the group that generates an acid when exposed to radiation include sulfonic acid and carboxylic acid. Examples of the radiation include those exemplified as radiation in the section <Method of forming a resist pattern> below.

[0050] Examples of the group that generates an acid when acted upon by radiation include a group containing an anion and a radiation-sensitive onium cation. Among these, a structure in which a group that generates a sulfonic acid when acted upon by radiation is bonded to a side chain of a polymer is preferred, and examples of such a group include a group represented by the following formula (x):

[0051]

[0052] In the above formula (x), R ａ１ is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted ring structure having five or more ring members. ａ１is 0 or 1. ａ１ is a single bond or a divalent linking group. ａ２ and R ａ３ are each independently a hydrogen atom, a fluoro group, or a substituted or unsubstituted hydrocarbon group. ａ２ is an integer from 0 to 10. ａ４ and R ａ５ are each independently an electron-withdrawing group. ａ３ is an integer from 0 to 10. ａ１ +n ａ２ +n ａ３ is 1 or more. ＋ is a monovalent radiation-sensitive onium cation. * is R in the above formula (1). ３ This is the binding site for

[0053] R ａ１ Examples of the ring structure having 5 or more ring members that gives the formula (I) include an aliphatic hydrocarbon ring having 5 or more ring members, an aliphatic heterocycle having 5 or more ring members, an aromatic hydrocarbon ring having 6 or more ring members, and an aromatic heterocycle having 5 or more ring members.

[0054] "Ring structure" includes "alicyclic ring" and "aromatic ring". "Alicyclic ring" includes "aliphatic hydrocarbon ring" and "aliphatic heterocyclic ring". Among alicyclic rings, polycyclic rings containing an aliphatic hydrocarbon ring and an aliphatic heterocyclic ring are considered to be "aliphatic heterocyclic ring". "Aromatic ring" includes "aromatic hydrocarbon ring" and "aromatic heterocyclic ring". Among aromatic rings, polycyclic rings containing an aromatic hydrocarbon ring and an aromatic heterocyclic ring are considered to be "aromatic heterocyclic ring".

[0055] Examples of the aliphatic hydrocarbon ring having 5 or more ring members include a monocyclic saturated alicyclic ring, a monocyclic unsaturated alicyclic ring, a polycyclic saturated alicyclic ring, and a polycyclic unsaturated alicyclic ring.

[0056] Examples of the aliphatic heterocyclic ring having 5 or more ring members include a lactone ring; a sultone ring; an oxygen atom-containing heterocyclic ring; a nitrogen atom-containing heterocyclic ring; and a sulfur atom-containing heterocyclic ring.

[0057] Examples of aromatic hydrocarbon rings having 6 or more ring members include the above-mentioned R ２ Examples of aromatic hydrocarbon rings which give the following rings include those given as examples.

[0058] Examples of aromatic heterocycles having 5 or more ring members include oxygen atom-containing heterocycles, nitrogen atom-containing heterocycles, and sulfur atom-containing heterocycles.

[0059] The ring structure is preferably an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring, and more preferably a polycyclic saturated alicyclic ring, a benzene ring, or a condensed polycyclic aromatic hydrocarbon ring.

[0060] The lower limit of the number of ring members in the ring structure is preferably 6, more preferably 8, still more preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 25.

[0061] In the ring structure, some or all of the hydrogen atoms bonded to the atoms constituting the ring structure may be substituted with a substituent. ２ Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include the groups exemplified above.

[0062] The term "linking group" refers to a group that links two or more structures.

[0063] L ａ１ Examples of the divalent linking group represented by ａ１ is not particularly limited as long as it is a group that connects two structures to which each of the groups is bonded, and examples thereof include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a sulfonyl group, an alkanediyl group having 1 to 10 carbon atoms, or a group combining these.

[0064] R ａ２ and R ａ３ Examples of hydrocarbon groups that give ３ Examples of the monovalent hydrocarbon groups having 1 to 20 carbon atoms include those exemplified in the description of the (n+1)-valent hydrocarbon groups which give the following formula:

[0065] R ａ２ and R ａ３ Examples of the substituents that may be possessed by the hydrocarbon group that gives the formula (I) include the above-mentioned R ２ Examples of the substituent that the aromatic hydrocarbon ring that gives the following may have include those exemplified above.

[0066] R ａ２ and R ａ３ is preferably a hydrogen atom.

[0067] n ａ２ is preferably 0 to 5, and more preferably 0 or 1.

[0068] R ａ４ and R ａ５ The electron-withdrawing group in is preferably a fluoro group, a fluorinated hydrocarbon group, a cyano group, a nitro group, an amido group, an alkyloxycarbonyl group, or an alkylsulfonyl group.

[0069] The fluorinated hydrocarbon group is preferably a fluorinated alkyl group, more preferably a perfluoroalkyl group, and even more preferably a trifluoromethyl group.

[0070] n ａ３ is preferably 1 to 5, and more preferably 1 or 2.

[0071] M ＋ Examples of the monovalent onium cation represented by the formula (I) include those known as radiation-sensitive onium cations in onium salts used as radiation-sensitive acid generators or acid diffusion controllers contained in radiation-sensitive compositions. For example, sulfonium cations (S ＋ ), iodonium cation (I ＋ ) are listed.

[0072] Examples of the monovalent radiation-sensitive onium cation include monovalent cations represented by the following formula (r-a) or (r-c) (hereinafter also referred to as "cation (r-a) or (r-c)").

[0073]

[0074] In the above formula (r-a), b1 is an integer of 0 to 4. When b1 is 1, R Ｂ１ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ１ 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 halogeno group, or a plurality of R Ｂ１ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached. b2 is an integer of 0 to 4. When b2 is 1, RＢ２ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ２ 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 halogeno group, or a plurality of R Ｂ２ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached. Ｂ３ and R Ｂ４ are each independently a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group, or R Ｂ３ and R Ｂ４ are combined with each other to form a polycyclic sulfur atom-containing aromatic heterocycle together with the sulfur atom to which they are bonded. b3 is an integer of 0 to 11. When b3 is 1, R Ｂ５ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ５ 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 halogeno group, or a plurality of R Ｂ５ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached. ｂ１ is an integer from 0 to 3.

[0075] In the above formula (rc), b6 is an integer of 0 to 5. When b6 is 1, R Ｂ９ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ９ 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 halogeno group, or a plurality of R Ｂ９ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are bonded. b7 is an integer of 0 to 5. When b7 is 1, R Ｂ１０ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ１０are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ１０ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached.

[0076] "Organic group" refers to a group containing at least one carbon atom.

[0077] R Ｂ１ , R Ｂ２ , R Ｂ５ , R Ｂ９ and R Ｂ１０ As the group, a perfluoroalkyl group, a fluoro group, an iodo group, a hydroxy group, an alkoxy group or a carboxy group is preferred, and a trifluoromethyl group, a fluoro group or an iodo group is more preferred.

[0078] R Ｂ３ and R Ｂ４ is preferably a hydrogen atom or a single bond formed by combining these, and is preferably a hydrogen atom.

[0079] b1 and b2 are preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. b3 is preferably 0 to 4, more preferably 0 to 2, and even more preferably 0 or 1. n ｂ１ is preferably 0 or 1.

[0080] Examples of the cation (ra) include cations represented by the following formulae (ra-1) to (ra-17).

[0081]

[0082] Examples of the cation (r-c) include cations represented by the following formulae (r-c-1) to (r-c-4).

[0083]

[0084] In the formula (1), examples of the linking group represented by L include the above-mentioned L ａ１ Among them, an alkanediyl group having 1 to 10 carbon atoms is preferred.

[0085] J is preferably *-COO-.

[0086] R ４ The number of carbon atoms in the acid-dissociable group represented by the formula (I) is usually 4 to 20, and preferably 4 to 12. When the number of carbon atoms in the acid-dissociable group is 4 to 12, sensitivity tends to be further improved compared to when the number of carbon atoms is outside the range of 4 to 12.

[0087] R ４ The acid-dissociable group represented by the formula (I) preferably contains a substituted or unsubstituted alicyclic ring having 3 to 9 ring members. In this case, the sensitivity tends to be further improved.

[0088] R ４ The acid-dissociable group represented by the formula (I) preferably contains a substituted or unsubstituted aromatic hydrocarbon ring. In this case, the sensitivity and LWR tend to be further improved.

[0089] R ４ The acid-dissociable group represented by the formula (I) preferably contains an aromatic hydrocarbon ring substituted with an iodo group. In this case, the LWR tends to be further improved.

[0090] R ４ Examples of the acid-dissociable group represented by the formula (a-1) include groups represented by the following formulas (a-1) and (a-2) (hereinafter also referred to as "acid-dissociable groups (a-1) and (a-2)").

[0091]

[0092] In the above formulas (a-1) and (a-2), * indicates the bonding site with J in the above formula (1).

[0093] In the above formula (a-1), R Ｘ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Ｙ and R Ｚ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other to form a saturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are attached.

[0094] In the above formula (a-2), R Ａ and R Ｂ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R Ａand R Ｂ are combined with each other to form an unsaturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are attached. Ｂ has a carbon atom forming a carbon-carbon double bond at the α-position of the carbon atom bonded to *.

[0095] R Ｘ , R Ｙ , R Ｚ , R Ａ , or R Ｂ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the formula ３ Examples of the monovalent hydrocarbon groups having 1 to 20 carbon atoms include those exemplified in the description of the (n+1)-valent hydrocarbon groups which give the following formula:

[0096] R Ｘ Examples of the substituent that the hydrocarbon group represented by the formula (I) may have include the above-mentioned R ２ Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include the groups exemplified above.

[0097] R Ｙ and R Ｚ Among the saturated alicyclic rings having 3 to 20 ring members formed by combining these rings together with the carbon atoms to which they are bonded, examples of the aliphatic hydrocarbon ring include monocyclic rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring; and polycyclic rings such as a norbornane ring, an adamantane ring, a tricyclodecane ring, and a tetracyclododecane ring.

[0098] R Ｙ and R Ｚ Among saturated alicyclic rings having 3 to 20 ring members formed by combining these rings together with the carbon atoms to which they are bonded, examples of the aliphatic heterocyclic ring include oxygen atom-containing heterocyclic rings such as tetrahydrofuran ring.

[0099] R Ａ and R Ｂ Examples of the unsaturated alicyclic ring having 3 to 20 ring members formed by combining these together with the carbon atoms to which they are bonded include monocyclic unsaturated alicyclic rings such as a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure, and polycyclic unsaturated alicyclic rings such as a norbornene structure.

[0100] RＹ and R Ｚ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R Ｙ and R Ｚ As R, a chain hydrocarbon group is preferable, an alkyl group is preferable, and a methyl group is more preferable. Ｘ As the alkyl group, a substituted or unsubstituted chain hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group is preferable, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group or a substituted or unsubstituted aryl group is more preferable, and a methyl group, a phenyl group or an iodophenyl group is even more preferable.

[0101] R Ｙ and R Ｚ When R are combined with each other to form a saturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are bonded, the saturated alicyclic ring is preferably a cyclopentane ring or a cyclohexane ring. Ｘ As the alkyl group, a substituted or unsubstituted chain hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group is preferable, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group or a substituted or unsubstituted aryl group is more preferable, and a methyl group, an ethyl group, an ethenyl group or a phenyl group is even more preferable.

[0102] R Ａ and R Ｂ are both monovalent hydrocarbon groups having 1 to 20 carbon atoms, R Ａ As R, a chain hydrocarbon group is preferable, an alkyl group is preferable, and a methyl group is more preferable. Ｂ As the alkyl group, a substituted or unsubstituted aromatic hydrocarbon group is preferable, a substituted or unsubstituted aryl group is more preferable, and an iodophenyl group is even more preferable.

[0103] R Ａ and R Ｂ When these are combined with each other to form an unsaturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are bonded, the unsaturated alicyclic ring is preferably a monocyclic unsaturated alicyclic ring, more preferably a cyclohexene ring.

[0104] Examples of the acid-dissociable group (a-1) include groups represented by the following formulae (a-1-1) to (a-1-7): Examples of the acid-dissociable group (a-2) include groups represented by the following formulae (a-2-1) to (a-2-2):

[0105]

[0106] In the above formula (1), n ​​is preferably 1 or 2.

[0107] Specific examples of the monomer that provides the structural unit (I) include the monomers (M-21) to (M-48) in the examples described later, as well as the monomers represented by the following formulas (M-90) to (M-97).

[0108]

[0109] The lower limit of the content of the structural unit (I) in the polymer [A] is preferably 1 mol %, more preferably 5 mol %, based on the total structural units constituting the polymer [A]. The upper limit of the content is preferably 60 mol %, more preferably 50 mol %, even more preferably 40 mol %, and particularly preferably 35 mol %. When the content is 35 mol % or less, the sensitivity tends to be further improved.

[0110] [Structural Unit (II)] The structural unit (II) is a structural unit containing a phenolic hydroxyl group. The term "phenolic hydroxyl group" refers not only to a hydroxyl group directly bonded to a benzene ring, but also to any hydroxyl group directly bonded to an aromatic ring.

[0111] In the case of KrF exposure, EUV exposure, or electron beam exposure, the polymer (A) containing the structural unit (II) can further enhance the sensitivity of the radiation-sensitive composition, and therefore the radiation-sensitive composition can be suitably used as a radiation-sensitive composition for KrF exposure, EUV exposure, or electron beam exposure.

[0112] Examples of the structural unit (II) include a structural unit represented by the following formula (II).

[0113]

[0114] In the above formula (II), R Ｐis a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. Ｐ is a single bond, *-COO-, -O-, or *-CONH-. * is R Ｐ indicates the bonding site with the carbon atom to which Ar is bonded. Ｐ represents a group in which (p+1) hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring, where p is an integer of 1 to 3.

[0115] R Ｐ From the viewpoint of copolymerizability of the monomer that gives the structural unit (II), a hydrogen atom or a methyl group is preferred.

[0116] L Ｐ is preferably a single bond or *-COO-.

[0117] Ar Ｐ The aromatic hydrocarbon ring giving the formula (I) preferably has 6 to 30 ring members, more preferably 6 to 20 ring members.

[0118] Ar Ｐ Examples of the aromatic hydrocarbon ring that gives ２ Examples of aromatic hydrocarbon rings which give the following rings include those given as examples.

[0119] Ar Ｐ Examples of the substituents in the aromatic hydrocarbon ring that give ２ Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include the groups exemplified above.

[0120] As p, 1 or 2 is preferred.

[0121] Examples of the structural unit (II) include structural units represented by the following formulae (II-1) to (II-21).

[0122]

[0123] In the above formulas (II-1) to (II-21), R Ｐ has the same meaning as in formula (II) above.

[0124] The lower limit of the content of the structural unit (II) in the polymer [A] is preferably 10 mol %, more preferably 20 mol %, based on all structural units constituting the polymer [A].The upper limit of the content is preferably 70 mol %, more preferably 60 mol %.

[0125] [Structural unit (III)] The structural unit (III) is a structural unit different from the structural unit (I) and contains an acid-dissociable group. In this specification, when the structural unit (III) also corresponds to the structural unit (II), it is included in the structural unit (III).

[0126] The acid-dissociable group is a group that substitutes a hydrogen atom of the carboxy group in the structural unit (III). In other words, in the structural unit (III), the acid-dissociable group is bonded to the etheric oxygen atom of the carbonyloxy group.

[0127] Examples of the acid-dissociable group include the above-mentioned R ４ Examples of the acid-dissociable group include the groups exemplified above as the acid-dissociable group represented by the following formula:

[0128] Examples of the structural unit (III) include a structural unit represented by the following formula (III).

[0129]

[0130] In the above formula (III), R Ｈ１ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. Ｈ is a single bond or *-COO-. * is R Ｈ１ indicates the bonding site with the carbon atom to which R is attached. Ｈ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. Ｈ２ When is a single bond, L Ｈ is a single bond. Ｈ３ is an acid-dissociable group.

[0131] R Ｈ１ From the viewpoint of copolymerizability of the monomer that gives the structural unit (III), a hydrogen atom or a methyl group is preferred.

[0132] L Ｈis preferably a single bond.

[0133] R Ｈ２ The aromatic hydrocarbon ring giving the formula (I) preferably has 6 to 30 ring members, more preferably 6 to 20 ring members.

[0134] R Ｈ２ Examples of the aromatic hydrocarbon ring that gives ２ Examples of aromatic hydrocarbon rings that give R Ｈ２ The aromatic hydrocarbon ring that gives the following is preferably a benzene ring.

[0135] R Ｈ２ Examples of the substituents that the aromatic hydrocarbon ring may have include the above-mentioned R ２ Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include the groups exemplified above.

[0136] R Ｈ２ may be a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring.

[0137] The lower limit of the content of the structural unit (III) in the polymer [A] is preferably 5 mol %, more preferably 10 mol %, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 70 mol %, more preferably 60 mol %. From the viewpoint of sensitivity, the content of the structural unit (III) in the polymer [A] is preferably 50 to 99 mol %, more preferably 70 to 97 mol %, and even more preferably 85 to 95 mol %, based on the total of the structural units (I) and (III) constituting the polymer [A]. From the viewpoint of LWR, the content of the structural unit (III) in the polymer [A] is preferably 1 to 85 mol %, more preferably 5 to 50 mol %, and even more preferably 10 to 30 mol %, based on the total of the structural units (I) and (III) constituting the polymer [A].

[0138] [Structural Unit (IV)] The structural unit (IV) is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. When the polymer (A) further contains the structural unit (IV), adhesion to the substrate can be improved.

[0139] Examples of the structural unit (IV) include structural units represented by the following formula:

[0140]

[0141]

[0142]

[0143]

[0144] In the above formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0145] The structural unit (IV) is preferably a structural unit containing a lactone structure.

[0146] When the polymer [A] has the structural unit (IV), the lower limit of the content of the structural unit (IV) is preferably 10 mol %, more preferably 20 mol %, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 60 mol %, more preferably 50 mol %.

[0147] [Structural Unit (V)] The structural unit (V) is a structural unit different from the structural unit (I) and contains a group that generates an acid when acted upon by radiation. The group that generates an acid when acted upon by radiation can be any of the groups described above in R ３ The substituents that may be possessed by the (n+1)-valent hydrocarbon group that gives the formula are described below.

[0148] When the polymer [A] contains the structural unit (V), the lower limit of the content of the structural unit (V) is preferably 10 mol %, more preferably 20 mol %, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 60 mol %, more preferably 50 mol %.

[0149] <[B] Acid Generator> The acid generator [B] is a substance that generates an acid when exposed to radiation. Examples of radiation include those exemplified as radiation in the section <Method of Forming a Resist Pattern> described below. The acid generated by the radiation dissociates acid-dissociable groups and generates carboxyl groups, which results in a difference in the solubility of the resist film in a developer between exposed and unexposed areas, allowing the formation of a resist pattern.

[0150] Examples of the acid generated from the acid generator (B) include sulfonic acid, carboxylic acid, and imide acid.

[0151] The acid generator (B) is not particularly limited as long as it is usable as a radiation-sensitive acid generator contained in the radiation-sensitive composition, and examples thereof include an onium salt compound, an N-sulfonyloxyimide compound, a sulfonimide compound, a halogen-containing compound, and a diazoketone compound.

[0152] Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

[0153] Specific examples of the acid generator (B) include the compounds described in paragraphs

[0080] to

[0113] of JP-A No. 2009-134088.

[0154] The acid generator (B) is preferably an onium salt compound, and more preferably an onium salt compound comprising a radiation-sensitive onium cation and an organic acid anion.

[0155] The radiation-sensitive onium cation in the acid generator (B) is not particularly limited as long as it is usable as a radiation-sensitive onium cation in a radiation-sensitive acid generator, and examples thereof include the radiation-sensitive onium cations described above in the section <Polymer (A)>.

[0156] The organic acid anion in the acid generator (B) is not particularly limited as long as it is usable as an anion in a radiation-sensitive acid generator, and examples thereof include a sulfonate anion.

[0157] As the acid generator (B), a compound in which the above-mentioned radiation-sensitive onium cation and the above-mentioned anion are appropriately combined can be used.

[0158] Specific examples of the structure of the acid generator [B] include the acid generators (B-1) to (B-4) in the examples described later.

[0159] The lower limit of the content of the acid generator [B] in the radiation-sensitive composition is preferably 10 parts by mass, more preferably 20 parts by mass, relative to 100 parts by mass of the polymer [A]. The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass. Note that when the structural unit (I) represented by formula (1) has a group that generates an acid when acted on by radiation, and when the polymer [A] has the structural unit (V), the lower limit of the content of the acid generator [B] may be 0 parts by mass, preferably 5 parts by mass, more preferably 10 parts by mass, relative to 100 parts by mass of the polymer [A]. The upper limit of the content is preferably 40 parts by mass, more preferably 30 parts by mass.

[0160] <Acid Diffusion Controller (C)> The acid diffusion controller (C) controls the diffusion phenomenon in the resist film of the acid generated from the acid generator (B) or the like upon exposure, thereby suppressing undesirable chemical reactions in unexposed areas. The radiation-sensitive composition may contain one or more acid diffusion controllers (C).

[0161] Examples of the acid diffusion controller (C) include nitrogen atom-containing compounds and compounds having a radiation-sensitive onium cation and an organic acid anion (hereinafter also referred to as "photodegradable bases").

[0162] Examples of the nitrogen atom-containing compound include amine compounds such as tripentylamine and trioctylamine; amide group-containing compounds such as formamide and N,N-dimethylacetamide; urea compounds such as urea and 1,1-dimethylurea; and nitrogen-containing heterocyclic compounds such as pyridine, N-(undecylcarbonyloxyethyl)morpholine, and N-t-pentyloxycarbonyl-4-hydroxypiperidine.

[0163] The photodegradable base generates a weak acid in the exposed area to increase the solubility or insolubility of the polymer (A) in a developer, thereby suppressing the surface roughness of the exposed area after development. On the other hand, in the unexposed area, the anion exerts a high acid-scavenging function and functions as a quencher, capturing acid diffusing from the exposed area.

[0164] Examples of the radiation-sensitive onium cation in the photodegradable base include the radiation-sensitive onium cations described above in the section <Polymer (A)>.

[0165] The organic acid anion in the photodegradable base is not particularly limited as long as it is usable as an organic acid anion in a photodegradable base, and examples thereof include carboxylate anions.

[0166] As the photodegradable base, a compound in which the above-mentioned radiation-sensitive onium cation and the above-mentioned anion are appropriately combined can be used.

[0167] Specific examples of the structure of the acid diffusion controller [C] include the acid diffusion controllers (C-1) to (C-4) in the examples described later.

[0168] When the radiation-sensitive composition contains the acid diffusion controller [C], the lower limit of the content of the acid diffusion controller [C] in the radiation-sensitive composition is preferably 5 mol %, more preferably 10 mol %, and even more preferably 15 mol %, relative to 100 mol % of the acid generator [B]. The upper limit of the content is preferably 100 mol %, more preferably 70 mol %, and even more preferably 60 mol %. Note that when the structural unit (I) represented by formula (1) has a group that generates a strong acid when acted on by radiation, and when the polymer [A] has a structural unit (V) containing a group that generates a strong acid when acted on by radiation, the content of the acid diffusion controller [C] is based on the total of the group contained in the polymer [A] that generates a strong acid when acted on by radiation and the acid generator [B]. Furthermore, when the structural unit (I) represented by formula (1) has a group that generates a weak acid when acted upon by radiation, and when the polymer (A) has a structural unit (V) that includes a group that generates a weak acid when acted upon by radiation, the lower limit of the content of the acid diffusion controller (C) may be 0 mol %.

[0169] <[D] Organic Solvent> The radiation-sensitive composition contains an organic solvent [D]. The organic solvent [D] is not particularly limited as long as it is a solvent that can dissolve or disperse at least the polymer [A], the acid generator [B], the acid diffusion controller [C], and other optional components that may be contained as needed.

[0170] Examples of the organic solvent (D) include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents. The radiation-sensitive composition may contain one or more organic solvents (D).

[0171] Examples of alcohol-based solvents include aliphatic monoalcohol-based solvents such as 4-methyl-2-pentanol, n-hexanol, diacetone alcohol, and methyl 2-hydroxyisobutyrate; alicyclic monoalcohol-based solvents such as cyclohexanol; polyhydric alcohol-based solvents such as 1,2-propylene glycol; and polyhydric alcohol partial ether-based solvents such as propylene glycol monomethyl ether.

[0172] Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

[0173] Examples of ketone solvents include chain ketone solvents such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, 2-heptanone, ethyl n-butyl ketone, methyl n-hexyl ketone, di-isobutyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; 2,4-pentanedione, acetonylacetone, and acetophenone.

[0174] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0175] Examples of ester-based solvents include monocarboxylic acid ester-based solvents such as n-butyl acetate and ethyl lactate; lactone-based solvents such as γ-butyrolactone and valerolactone; polyhydric alcohol carboxylate-based solvents such as propylene glycol acetate; polyhydric alcohol partial ether carboxylate-based solvents such as propylene glycol monomethyl ether acetate; polycarboxylic acid diester-based solvents such as diethyl oxalate; and carbonate-based solvents such as dimethyl carbonate and diethyl carbonate.

[0176] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane and n-hexane; and aromatic hydrocarbon solvents such as toluene and xylene.

[0177]

[0033] The organic solvent (D) is preferably an alcohol solvent, an ester solvent, or a combination thereof, more preferably an aliphatic monoalcohol solvent, a polyhydric alcohol partial ether solvent, a polyhydric alcohol partial ether carboxylate solvent, or a combination thereof, and even more preferably diacetone alcohol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or a combination thereof.

[0178] When the radiation-sensitive composition contains the organic solvent (D), the lower limit of the content of the organic solvent (D) is preferably 50 mass %, more preferably 60 mass %, still more preferably 70 mass %, and particularly preferably 80 mass %, based on all components contained in the radiation-sensitive composition, and the upper limit of the content is preferably 99.9 mass %, preferably 99.5 mass %, and more preferably 99.0 mass %.

[0179] <Other Optional Components> Examples of other optional components include surfactants, etc. The radiation-sensitive composition may contain one or more other optional components.

[0180] <Method of Forming a Resist Pattern> The method of forming a resist pattern includes a step of applying a radiation-sensitive composition directly or indirectly to a substrate (hereinafter also referred to as a "coating step"), a step of exposing the resist film formed in the coating step (hereinafter also referred to as an "exposure step"), and a step of developing the exposed resist film (hereinafter also referred to as a "developing step").

[0181] In the coating step, the radiation-sensitive composition is the radiation-sensitive composition described above. Therefore, according to the method for forming a resist pattern, a resist pattern having excellent sensitivity and LWR and a wide process window can be formed.

[0182] Each step of the resist pattern forming method will be described below.

[0183] [Coating Step] In this step, the radiation-sensitive composition is coated directly or indirectly onto a substrate, thereby forming a resist film directly or indirectly on the substrate.

[0184] In this step, the radiation-sensitive composition described above is used as the radiation-sensitive composition.

[0185] Substrates include, for example, silicon wafers, silicon dioxide, and aluminum coated wafers.

[0186] Examples of coating methods include spin coating, casting coating, and roll coating. After coating, if necessary, pre-baking (hereinafter also referred to as "PB") may be performed to volatilize the solvent in the coating film. The PB temperature and PB time are not particularly limited, and are, for example, performed at a temperature of 60°C to 150°C for 5 seconds to 300 seconds. The average thickness of the formed resist film is not particularly limited, and is, for example, 10 nm to 1,000 nm.

[0187] [Exposure Step] In this step, the resist film formed in the coating step is exposed to radiation. This exposure is carried out by irradiating the resist film through a photomask (or, in some cases, through an immersion medium such as water). The radiation can be appropriately selected depending on the line width, diameter, etc. of the desired pattern, and examples thereof include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, EUV, or electron beams are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm), or electron beams being more preferred, with KrF excimer laser light, EUV, or electron beams being even more preferred, and EUV or electron beams being particularly preferred.

[0188] After the exposure, it is preferable to perform post-exposure baking (hereinafter also referred to as "PEB"). This PEB can increase the difference in solubility in a developer between the exposed and unexposed areas. The PEB temperature and PEB time are not particularly limited, and can be performed, for example, at a temperature of 50°C to 180°C for 5 to 600 seconds.

[0189] [Development Step] In this step, the exposed resist film is developed. This allows a predetermined resist pattern to be formed. The development method in the development step may be alkali development or organic solvent development.

[0190] In the case of alkaline development, examples of the developer used for development include alkaline aqueous solutions containing at least one alkaline compound dissolved therein, 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 (hereinafter also referred to as "TMAH"), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred.

[0191] In the case of organic solvent development, examples of the developer include the organic solvents exemplified above as the organic solvent (D) of the radiation-sensitive composition.

[0192] <Polymer> The polymer is the polymer (A) described above. The polymer can be suitably used as a base resin for a radiation-sensitive composition.

[0193] Specific structures of the polymer include, for example, polymers (A-1) to (A-49) in the examples described below.

[0194] <Monomer> The monomer is a monomer represented by the following formula (m1): This monomer can be suitably used as a monomer for synthesizing a base resin of a radiation-sensitive composition.

[0195]

[0196] In the above formula (m1), R ｍ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ｍ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ｍ３ is a substituted or unsubstituted (n ｍ +1)-valent aromatic hydrocarbon group. ｍ is a single bond or a divalent linking group. ｍis *-COO- or -O-. ｍ The binding site with R ｍ４ is an acid-dissociable group. ｍ is an integer from 1 to 5. ｍ If there are two or more L ｍ are the same or different, and multiple J ｍ are the same or different, and multiple R ｍ４ are the same or different from each other.

[0197] In the above formula (m1), R ｍ１ , R ｍ２ , L ｍ , J ｍ and n ｍ represents R in formula (1) in the above section <Polymer (A)>. １ , R ２ , L, J and n.

[0198] In the above formula (m1), R ｍ１ Examples of the aromatic hydrocarbon group that gives the formula include R ３ The same applies to the substituent.

[0199] In the above formula (m1), R ｍ４ Examples of the acid-dissociable group represented by the formula (I) include the acid-dissociable groups (a-1-2) to (a-1-8) and (a-2-1) in the section <Polymer (A)>> above.

[0200] The monomer may be any of the following: ｍ１ R can be a hydrogen atom or a methyl group. ｍ２ R may be a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ｍ３ As the hydroxyl group-substituted (n ｍ +1)-valent hydrocarbon group, substituted with a group that generates an acid when exposed to radiation (n ｍ L can be a hydrocarbon group with a valence of 1. ｍ R may be a divalent linking group. ｍ４The acid-dissociable group represented by R may contain a substituted or unsubstituted aromatic hydrocarbon ring, and preferably contains an aromatic hydrocarbon group substituted with an iodo group. ｍ４ is a group represented by the above formula (a-2), and R Ａ and R Ｂ may each independently be a monovalent hydrocarbon group having 1 to 20 carbon atoms. ｍ can be 2 to 5.

[0201] More specific examples of the monomer structures include the monomers (M-21) to (M-48) in the examples described below.

[0202] <Method of synthesizing the monomer> The monomer can be synthesized by a known method. Specifically, the following synthesis methods 1 to 4 can be mentioned. 1. R ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ - (L ｍ -COOH)n ｍ and a carboxylic acid compound represented by R ｍ４ 2. A method of condensing with an alcohol compound represented by —OH. ｍ１ -C(=CH ２ )-R ｍ２ A carboxylic acid compound represented by -COOH and H ２ N-R ｍ３ - (L ｍ -J ｍ -R ｍ４ ) n ｍ 3. A method of condensing with an amine compound represented by R ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ Alcohol compounds represented by -OH and Hal-L ｍ -J ｍ -R ｍ４ wherein Hal is a halogen atom. 4. A method of reacting a halogenated compound represented by the formula: ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ A carboxylic acid compound represented by —COOH and Hal-L ｍ-J ｍ -R ｍ４ wherein Hal is a halogen atom.

[0203] More specific examples of the method for synthesizing the monomers include the methods described in Synthesis Examples 1-1 to 1-28 in the Examples below.

[0204] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0205] <Synthesis of Monomer [M]> According to the following method, the following formulae (M-21) to (M-48) (hereinafter also referred to as "monomers (M-21) to (M-48)") were synthesized.

[0206]

[0207] [Synthesis Example 1-1] Synthesis of Monomer (M-21) Monomer (M-21) was synthesized according to the following reaction scheme.

[0208]

[0209] 40 mmol of 4-aminobenzoic acid and 50 mL of a 4N aqueous sodium hydroxide solution were added to a reaction vessel and dissolved, and then cooled to 0°C. 80 mmol of methacryloyl chloride was added dropwise at 0°C, and the mixture was stirred at room temperature for 3 hours. The solid was filtered and washed with ethyl acetate to obtain a compound represented by the above formula (pM-21) (hereinafter also referred to as "compound (pM-21)").

[0210] A reaction vessel was charged with 30 mmol of compound (pM-21), 33 mmol of 1-methylcyclopentanol, 33 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (hereinafter also referred to as "EDC"), 6 mmol of 4-dimethylaminopyridine (hereinafter also referred to as "DMAP"), and 50 mL of dichloromethane (hereinafter also referred to as "DCM"), and the mixture was stirred at room temperature for 2 hours. 20 mL of 2 M hydrochloric acid was added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. The mixture was then dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography yielded monomer (M-21).

[0211] [Synthesis Examples 1-2 to 1-4] Synthesis of Monomers (M-22) to (M-24) Monomers (M-22) to (M-24) were synthesized in the same manner as in Synthesis Example 1-1, except that the substrates used were appropriately selected.

[0212] [Synthesis Example 1-5] Synthesis of Monomer (M-25) Monomer (M-25) was synthesized according to the following reaction scheme.

[0213]

[0214] A reaction vessel was charged with 50 mmol of 4-vinylbenzoic acid, 2 mmol of N,N-dimethylformamide, and 100 mL of acetonitrile, and the mixture was cooled to 0° C. 80 mmol of oxalyl dichloride was added dropwise, and the mixture was stirred at room temperature for 1 hour. The solvent was then removed to obtain a compound represented by formula (ppM-25) above (hereinafter also referred to as "compound (ppM-25)").

[0215] 40 mmol of 4-aminobenzoic acid and 50 mL of a 4N aqueous sodium hydroxide solution were added to a reaction vessel and dissolved, and then cooled to 0°C. 40 mmol of compound (ppM-25) dissolved in 20 mL of acetonitrile at 0°C was added dropwise, and the mixture was stirred at room temperature for 3 hours. The solid was filtered and washed with ethyl acetate to obtain a compound represented by the above formula (pM-25) (hereinafter also referred to as "compound (pM-25)").

[0216] 30 mmol of compound (pM-25), 33 mmol of 1-methylcyclopentanol, 33 mmol of EDC, 6 mmol of DMAP, and 50 mL of DCM were added to a reaction vessel and stirred at room temperature for 2 hours. 20 mL of 2 M hydrochloric acid was added to separate the organic layer. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. It was then dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography yielded monomer (M-25).

[0217] [Synthesis Example 1-6] Synthesis of Monomer (M-26) Monomer (M-26) was synthesized according to the following reaction scheme.

[0218]

[0219] A reaction vessel was charged with 55 mmol of N-Fmoc-glycine, 100 mL of dichloromethane, and 55 mmol of 1-methylcyclopentanol, and the mixture was cooled to 0°C. 6 mmol of DMAP and 55 mmol of N,N-dicyclohexylcarbodiimide (hereinafter also referred to as "DCC") were added, and the mixture was stirred at room temperature for 3 hours. 100 mmol of diazabicycloundecene was added, and the mixture was stirred at room temperature for 1 hour. The solid was filtered and then washed with dichloromethane. Purification by silica gel chromatography gave the compound represented by the above formula (pM-26) (hereinafter also referred to as "compound (pM-26)").

[0220] A reaction vessel was charged with 33 mmol of 4-vinylbenzoic acid, 33 mmol of 1,1-carbonyldiimidazole (hereinafter also referred to as "CDI"), and 30 mL of acetonitrile, and the mixture was stirred at room temperature for 1 hour. 30 mmol of compound (pM-26) and 60 mmol of diazabicycloundecene were added, and the mixture was stirred at room temperature for 3 hours. 30 mL of 2 M hydrochloric acid and 50 mL of ethyl acetate were added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. It was then dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography yielded monomer (M-26).

[0221] Synthesis Example 1-7 (Synthesis of Monomer (M-27)) Monomer (M-27) was synthesized in the same manner as in Synthesis Example 1-6, except that the substrate used was appropriately selected.

[0222] [Synthesis Examples 1-8 to 1-14] Synthesis of Monomers (M-28) to (M-34) Monomers (M-28) to (M-34) were synthesized in the same manner as in Synthesis Example 1-1, except that the substrates used were appropriately selected.

[0223] Synthesis Example 1-15 (Synthesis of Monomer (M-35)) Monomer (M-35) was synthesized according to the following reaction scheme.

[0224]

[0225] 40 mmol of 4-amino-2-hydroxybenzoic acid and 50 mL of a 4N aqueous sodium hydroxide solution were added to a reaction vessel and dissolved, and then cooled to 0°C. 80 mmol of methacryloyl chloride was added dropwise at 0°C, and the mixture was stirred at room temperature for 3 hours. The solid was filtered and washed with ethyl acetate to obtain a compound represented by the above formula (pM-35) (hereinafter also referred to as "compound (pM-25)").

[0226] 30 mmol of compound (pM-35), 33 mmol of CDI, and 30 mL of N,N-dimethylformamide were added to a reaction vessel and stirred at room temperature for 1 hour. 33 mmol of 1-methylcyclopentanol and 60 mmol of diazabicycloundecene were added, and stirred at room temperature for 3 hours. 30 mL of 2 M hydrochloric acid and 50 mL of ethyl acetate were added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. It was then dried over anhydrous sodium sulfate, and the solvent was removed. The mixture was purified by silica gel chromatography to obtain monomer (M-35).

[0227] [Synthesis Examples 1-17 to 1-20] Synthesis of Monomers (M-37) to (M-40) Monomers (M-37) to (M-40) were synthesized in the same manner as in Synthesis Example 1-1, except that the substrates used were appropriately selected.

[0228] Synthesis Example 1-21 Synthesis of Monomer (M-41) Monomer (M-41) was synthesized in the same manner as in Synthesis Example 1-15, except that the substrate used was appropriately selected.

[0229] Synthesis Example 1-22 Synthesis of Monomer (M-42) Monomer (M-42) was synthesized according to the following reaction scheme.

[0230]

[0231] 40 mmol of 5-aminoisophthalic acid and 50 mL of a 4N aqueous sodium hydroxide solution were added to a reaction vessel and dissolved, and then cooled to 0°C. 80 mmol of methacryloyl chloride was added dropwise at 0°C, and the mixture was stirred at room temperature for 3 hours. The solid was filtered and washed with ethyl acetate to obtain a compound represented by the above formula (pM-42) (hereinafter also referred to as "compound (pM-42)").

[0232] A reaction vessel was charged with 30 mmol of compound (pM-42), 63 mmol of 1-methylcyclopentanol, 63 mmol of EDC, 6 mmol of DMAP, and 50 mL of DCM, and the mixture was stirred at room temperature for 2 hours. 20 mL of 2 M hydrochloric acid was added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. The mixture was then dried over anhydrous sodium sulfate, and the solvent was removed. The mixture was purified by silica gel chromatography to obtain monomer (M-42).

[0233] Synthesis Example 1-23 Synthesis of Monomer (M-43) Monomer (M-43) was synthesized in the same manner as in Synthesis Example 1-22, except that the substrate used was appropriately selected.

[0234] Synthesis Example 1-24 Synthesis of Monomer (M-44) Monomer (M-44) was synthesized according to the following reaction scheme.

[0235]

[0236] 20 mmol of the compound represented by formula (M-35) above (monomer (M-35) described below), 20 mmol of the compound represented by formula (S-1) above, 22 mmol of potassium carbonate, and 30 mL of N,N-dimethylformamide were added to a reaction vessel and stirred at room temperature for 2 hours. 30 mL of 2 M hydrochloric acid and 50 mL of ethyl acetate were added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium hydrogen carbonate solution and once with 40 mL of ultrapure water. The mixture was then dried over anhydrous sodium sulfate, and the solvent was removed. The mixture was purified by silica gel chromatography to obtain monomer (M-44).

[0237] Synthesis Example 1-25 Synthesis of Monomer (M-45) Monomer (M-45) was synthesized in the same manner as in Synthesis Example 1-22, except that the substrate used was appropriately selected.

[0238] Synthesis Example 1-26 Synthesis of Monomer (M-46) Monomer (M-46) was synthesized according to the following reaction scheme.

[0239]

[0240] 40 mmol of 5-amino-2,4,6-triiodoisophthalic acid and 50 mL of a 4N aqueous sodium hydroxide solution were added to a reaction vessel and dissolved, and then cooled to 0°C. 80 mmol of methacryloyl chloride was added dropwise at 0°C, and the mixture was stirred at room temperature for 3 hours. The solid was filtered and washed with ethyl acetate to obtain a compound represented by the above formula (pM-46) (hereinafter also referred to as "compound (pM-46)").

[0241] 20 mmol of compound (pM-46), 40 mmol of the compound represented by formula (S-2) above, 42 mmol of potassium carbonate, and 40 mL of N,N-dimethylformamide were added to a reaction vessel and stirred at room temperature for 2 hours. 30 mL of 2 M hydrochloric acid and 50 mL of ethyl acetate were added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. It was then dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography yielded monomer (M-46).

[0242] Synthesis Example 1-27 Synthesis of Monomer (M-47) Monomer (M-47) was synthesized according to the following reaction scheme.

[0243]

[0244] 30 mmol of compound (pM-35), 33 mmol of CDI, and 30 mL of N,N-dimethylformamide were added to a reaction vessel and stirred at room temperature for 1 hour. 33 mmol of the compound represented by formula (S-3) above and 60 mmol of diazabicycloundecene were added and stirred at room temperature for 3 hours. 30 mL of 2 M hydrochloric acid and 50 mL of ethyl acetate were added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. It was then dried over anhydrous sodium sulfate, and the solvent was removed. The mixture was purified by silica gel chromatography to obtain the compound represented by formula (pM-47) above (hereinafter also referred to as "compound (pM-47)").

[0245] 20 mmol of compound (pM-47), 20 mmol of the compound represented by formula (S-2), 22 mmol of potassium carbonate, and 30 mL of N,N-dimethylformamide were added to a reaction vessel and stirred at room temperature for 2 hours. 30 mL of 2 M hydrochloric acid and 50 mL of ethyl acetate were added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. It was then dried over anhydrous sodium sulfate, and the solvent was removed. Purification by silica gel chromatography yielded monomer (M-47).

[0246] Synthesis Example 1-28 Synthesis of Monomer (M-48) Monomer (M-48) was synthesized according to the following reaction scheme.

[0247]

[0248] 40 mmol of 4-amino-2-hydroxybenzaldehyde and 50 mL of a 4N aqueous sodium hydroxide solution were added to a reaction vessel and dissolved, and then cooled to 0°C. 80 mmol of methacryloyl chloride was added dropwise at 0°C, and the mixture was stirred at room temperature for 3 hours. The solid was filtered and washed with ethyl acetate to obtain a compound represented by the above formula (ppM-48) (hereinafter also referred to as "compound (ppM-48)").

[0249] A reaction vessel was charged with 30 mmol of the compound represented by formula (S-4) above, 30 mmol of compound (ppM-48), 4 mmol of p-toluenesulfonic acid (pTsOH), and 100 mL of toluene. A Dean-Stark tube was installed in the reaction vessel, and the mixture was heated and stirred under reflux conditions for 4 hours. 50 mL of saturated aqueous sodium bicarbonate solution was added, and the organic layer was separated. The organic layer was dried over anhydrous sodium sulfate, and the solvent was removed. The mixture was purified by silica gel chromatography to obtain a compound represented by formula (pM-48) above (hereinafter also referred to as "compound (pM-48)").

[0250] 20 mmol of compound (pM-48), 20 mmol of the compound represented by formula (S-2) above, 22 mmol of potassium carbonate, and 30 mL of N,N-dimethylformamide were added to a reaction vessel and stirred for 2 hours at room temperature. 30 mL of 2 M hydrochloric acid and 50 mL of ethyl acetate were added, and the organic layer was separated. The organic layer was washed twice with 40 mL of saturated aqueous sodium bicarbonate solution and once with 40 mL of ultrapure water. It was then dried over anhydrous sodium sulfate, and the solvent was removed. The mixture was purified by silica gel chromatography to obtain monomer (M-48).

[0251] <Synthesis of Polymer [A]> [Synthesis Examples 2-1 to 2-53] Synthesis of Polymers (A-1) to (A-53) The monomers were combined according to the compositions shown in Table 1 below, and copolymerization was carried out in tetrahydrofuran (THF) solvent. The resulting polymers were crystallized in methanol, repeatedly washed with hexane, and then isolated and dried to synthesize Polymers (A-1) to (A-53). Compounds represented by the following formulae (M-1) to (M-20) (hereinafter also referred to as "Monomers (M-1) to (M-20)") and Monomers (M-21) to (M-48) were used to synthesize Polymer [A]. The Mw and Mw / Mn of the resulting polymers were confirmed by GPC as described above in the section [Method for Measuring Mw and Mn].

[0252]

[0253]

[0254] <Preparation of Radiation-Sensitive Composition> The acid generator [B], the acid diffusion controller [C], and the organic solvent [D] used in the preparation of the radiation-sensitive composition are shown below. In the following examples and comparative examples, unless otherwise specified, "parts by mass" means a value when the mass of the polymer [A] used is taken as 100 parts by mass.

[0255] [[B] Acid Generator] As the acid generator [B], compounds represented by the following formulas (B-1) to (B-5) (hereinafter also referred to as "acid generators (B-1) to (B-5)") were used.

[0256]

[0257] [[C] Acid Diffusion Controller] As the acid diffusion controller [C], compounds represented by the following formulas (C-1) to (C-5) (hereinafter also referred to as "acid diffusion controllers (C-1) to (C-5)") were used.

[0258]

[0259] [[D] Organic Solvent] The following organic solvents were used as the organic solvent [D]: (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol monomethyl ether (D-3): Diacetone alcohol

[0260] Example 1 Preparation of Radiation-Sensitive Composition (R-1) 100 parts by mass of polymer (A-1), 30 parts by mass of acid generator (B-1), 50 mol % of acid diffusion controller (C-1) based on acid generator (B-1), 2,000 parts by mass of organic solvent (D-1), and 4,800 parts by mass of organic solvent (D-2) were blended together. The resulting mixture was filtered through a membrane filter with a pore size of 0.20 μm to prepare radiation-sensitive composition (R-1).

[0261] Examples 2 to 59 and Comparative Examples 1 to 5 Preparation of Radiation-Sensitive Compositions (R-2) to (R-59) and (CR-1) to (CR-5) Radiation-sensitive compositions (R-2) to (R-56) and (CR-1) to (CR-4) were prepared in the same manner as in Example 1, except that the types and blending amounts of each component shown in Table 2 below were used.

[0262] In Table 2 below, "-" indicates that the corresponding component was not used. In Table 2 below, the content of the acid diffusion controller (C) refers to the molar ratio relative to the radiation-sensitive acid-generating component.

[0263]

[0264] <Formation of Resist Pattern> Each of the radiation-sensitive compositions prepared above was applied to the surface of a 12-inch silicon wafer on which a 40-nm-thick underlayer film (AL412 (manufactured by Brewer Science)) had been formed, using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). After PB at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 50-nm-thick resist film. Next, this resist film was irradiated with EUV using an EUV exposure machine (ASML's "NXE3300", NA = 0.33, illumination conditions: Conventional s = 0.89, mask: imecDEFECT32FFR02). The resist film was subjected to PEB at 110°C for 60 seconds. The resist was then developed with a 2.38% by mass aqueous solution of TMAH at 23° C. for 30 seconds to form a positive 32 nm line and space pattern.

[0265] <Evaluation> The sensitivity, LWR, and process window were evaluated according to the following methods. The results are shown in Table 3 below.

[0266] [Sensitivity] The exposure dose at which the resist pattern was formed in the above section <Formation of Resist Pattern> was taken as the optimum exposure dose, and this value was used to determine the sensitivity (unit: mJ / cm ２ The smaller the sensitivity value, the more favorable the desired resist pattern could be formed with a smaller exposure dose.

[0267] [LWR] The resist pattern formed in the above section <Formation of Resist Pattern> was observed from above the pattern using a scanning electron microscope ("CG-4100" manufactured by Hitachi High-Tech Corporation). A total of 50 line widths were measured at random locations. A 3 sigma value was calculated from the distribution of the measured values, and the calculated 3 sigma value was taken as the LWR (unit: nm). The smaller the LWR value, the smaller the line rattle, and the better the evaluation.

[0268] [Process Window] Using a mask that forms 32 nm lines and spaces (1L / 1S), patterns were formed by varying the exposure dose from low to high. Generally, connections between patterns are observed at the low exposure dose, while defects such as pattern collapse are observed at the high exposure dose. The difference between the upper and lower limits of the resist dimensions where these defects are not observed was defined as the "CD (Critical Dimension) margin." The larger the CD margin value, the wider the process window is considered to be. The process window was evaluated as "A" (very good) when the CD margin value was 37 nm or more, "B" (good) when it was 34 nm or more but less than 37 nm, "C" (fair) when it was 33 nm or more but less than 34 nm, and "D" (poor) when it was less than 33 nm.

[0269]

[0270] It can be seen from Table 3 that the radiation-sensitive compositions of Examples 1 to 59 all had better sensitivity, LWR and process window than the radiation-sensitive compositions of Comparative Examples 1 to 5.

Claims

1. A radiation-sensitive composition comprising a polymer having a structural unit (I) represented by the following formula (1) and a structural unit (II) containing a phenolic hydroxyl group, and an organic solvent. (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ３ is a substituted or unsubstituted (n+1)-valent hydrocarbon group. L is a single bond or a divalent linking group. J is *-COO- or -O-. * indicates the bonding site with L. R ４ is an acid-dissociable group. n is an integer of 1 to 5. When n is 2 or more, multiple Ls may be the same or different, multiple Js may be the same or different, and multiple Rs may be the same or different. ４ are the same or different.) 2. R ３ 2. The radiation-sensitive composition according to claim 1, wherein is a substituted or unsubstituted (n+1)-valent aromatic hydrocarbon group or a substituted or unsubstituted (n+1)-valent chain hydrocarbon group.

3. n is 1 and R ３ 3. The radiation-sensitive composition according to claim 2, wherein is an o-phenylene group or a p-phenylene group.

4. R ４ The radiation-sensitive composition according to claim 1, wherein is represented by the following formulas (a-1) and (a-2): (In formulas (a-1) and (a-2), * indicates the bonding site with J in formula (1). In formula (a-1), R Ｘ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Ｙ and R Ｚ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other to form a saturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are attached. Ａ and R Ｂ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R Ａ and R Ｂ are combined with each other to form an unsaturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are attached. Ｂ has a carbon atom forming a carbon-carbon double bond at the α-position of the carbon atom bonded to *.) 5. R ４ 2. The radiation-sensitive composition according to claim 1, wherein the ring structure includes a substituted or unsubstituted alicyclic ring having 3 to 9 ring members.

6. R ４ 2. The radiation-sensitive composition according to claim 1, wherein the aromatic hydrocarbon ring is a substituted or unsubstituted aromatic hydrocarbon ring.

7. R ４ 7. The radiation-sensitive composition according to claim 6, wherein the aromatic hydrocarbon is substituted with an iodo group.

8. A method for forming a resist pattern, comprising the steps of: applying the radiation-sensitive composition according to any one of claims 1 to 7 directly or indirectly to a substrate; exposing a resist film formed by the coating; and developing the exposed resist film.

9. A polymer having a structural unit (I) represented by the following formula (1) and a structural unit (II) containing a phenolic hydroxyl group: (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ３ is a substituted or unsubstituted (n+1)-valent hydrocarbon group. L is a single bond or a divalent linking group. J is *-COO- or -O-. * indicates the bonding site with L. R ４ is an acid-dissociable group. n is an integer of 1 to 5. When n is 2 or more, multiple Ls may be the same or different, multiple Js may be the same or different, and multiple Rs may be the same or different. ４ are the same or different.) 10. A monomer represented by the following formula (m1): (In formula (m1), R ｍ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ｍ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ｍ３ is a substituted or unsubstituted (n ｍ +1)-valent aromatic hydrocarbon group. ｍ is a single bond or a divalent linking group. ｍ is *-COO- or -O-. ｍ The binding site with R ｍ４ is an acid-dissociable group. ｍ is an integer from 1 to 5. ｍ If there are two or more L ｍ are the same or different, and multiple J ｍ are the same or different, and multiple R ｍ４ are the same or different.) 11. A method for synthesizing a monomer represented by the following formula (m1) which is any one of the following 1. to 4.:

1. R ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ - (L ｍ -COOH)n ｍ and a carboxylic acid compound represented by R ｍ４ 2. A method of condensing with an alcohol compound represented by —OH. ｍ１ -C(=CH ２ )-R ｍ２ A carboxylic acid compound represented by -COOH and H ２ N-R ｍ３ - (L ｍ -J ｍ -R ｍ４ ) n ｍ 3. A method of condensing with an amine compound represented by R ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ Alcohol compounds represented by -OH and Hal-L ｍ -J ｍ -R ｍ４ (Hal is a halogen atom). ｍ１ -C(=CH ２ )-R ｍ２ -CONH-R ｍ３ A carboxylic acid compound represented by —COOH and Hal-L ｍ -J ｍ -R ｍ４ (Hal is a halogen atom). (In formula (m1), R ｍ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ｍ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. ｍ３ is a substituted or unsubstituted (n ｍ +1)-valent aromatic hydrocarbon group. ｍ is a single bond or a divalent linking group. ｍ is *-COO- or -O-. ｍ The binding site with R ｍ４ is an acid-dissociable group. ｍ is an integer from 1 to 5. ｍ If there are two or more L ｍ are the same or different, and multiple J ｍ are the same or different, and multiple R ｍ４ are the same or different.)

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