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

Abstract

Provided is a radiation-sensitive composition comprising a polymer having structural monomer A that contains a moiety in which a hydrogen atom of a carboxy group is substituted by an acid dissociable group represented by formula (z).

Description

Radiation-sensitive composition, resist pattern forming method, polymer and monomer

[0001] The present invention relates to a radiation-sensitive composition, a method for forming a resist pattern, a polymer, and a 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] The radiation-sensitive composition is required to have good sensitivity to radiation such as extreme ultraviolet rays and electron beams, as well as excellent CDU (Critical Dimension Uniformity) and suppressed occurrence of development defects.

[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 CDU and suppress the occurrence of development defects. Another object of the present invention is to provide a polymer that is suitable as a component of the radiation-sensitive composition. A still further object of the present invention is to provide a monomer that is suitable for synthesizing the polymer.

[0008] The invention made to solve the above-mentioned problems provides a radiation-sensitive composition containing a polymer (hereinafter also referred to as a “[P] polymer”) having a structural unit A including a partial structure in which a hydrogen atom of a carboxy group is substituted with an acid-dissociable group represented by the following formula (z) (hereinafter also referred to as an “acid-dissociable group (z)”): (In formula (z), R １ is a group obtained by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic heterocycle. １ is a group obtained by removing (n+1) hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring. X is an iodo group or a bromo group. n is an integer of 1 or more. * indicates the bonding site with the etheric oxygen atom of the carboxy group.

[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] Yet another invention made to solve the above problems is the above-mentioned [P] polymer.

[0011] Yet another invention made to solve the above problems is a monomer represented by the following formula (ma) (hereinafter also referred to as "monomer [A]"). (In formula (ma), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, —O—, —COO— or —CONH—. ２represents a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic ring. Z represents the acid-dissociable group (z) described above.

[0012] The radiation-sensitive composition of the present invention is excellent in sensitivity and CDU, and the occurrence of development defects is suppressed. According to the method for forming a resist pattern of the present invention, a resist pattern can be formed that is excellent in sensitivity and CDU, and the occurrence of development defects is suppressed. 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. Therefore, these can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

[0013] The radiation-sensitive composition, method of forming a resist pattern, polymer and monomer of the present invention will be described in detail below.

[0014] Unless otherwise specified, the description of the upper and lower limits of a numerical range in this specification may be "less than or equal to" or "less than," and the lower limit may be "greater than or equal to" or "greater than." The upper and lower limits may 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."

[0015] <Radiation-Sensitive Composition> The radiation-sensitive composition contains a polymer (polymer [P]) having a structural unit A including a partial structure in which a hydrogen atom of a carboxy group is substituted with an acid-dissociable group represented by formula (z) described below (acid-dissociable group (z)).

[0016] The radiation-sensitive composition having the above-described structure exhibits the effects of excellent sensitivity and CDU and suppressing the occurrence of development defects. The reason for this is not entirely clear, but is presumed to be, for example, as follows: The polymer [P] has a structural unit A containing an iodine group or a bromo group, which improves the radiation absorption efficiency and acid generation efficiency. This improves sensitivity. Although most of the acid-dissociable groups (z) in the polymer dissociate in the exposed areas, some of the acid-dissociable groups (z) may remain without dissociating, which may lead to a deterioration in CDU or the occurrence of development defects. Because the acid-dissociable group (z) contains an aliphatic heterocycle and has appropriate polarity, even if the acid-dissociable group (z) remains without dissociating, the risk of this causing a deterioration in CDU or the occurrence of development defects is reduced. As a result, it is believed that the radiation-sensitive composition of the present invention exhibits excellent sensitivity and CDU and suppresses the occurrence of development defects.

[0017] The radiation-sensitive composition typically contains an organic solvent (hereinafter also referred to as "organic solvent [D]"). The radiation-sensitive composition typically contains a radiation-sensitive acid generator. Examples of the radiation-sensitive acid generator include the [P] polymer itself when the [P] polymer has a structural unit containing a group that generates an acid under the action of radiation. Examples of the radiation-sensitive acid generator include a radiation-sensitive acid generator (hereinafter also referred to as "acid generator [B]") as a component other than the [P] polymer. The radiation-sensitive composition may also contain an acid diffusion controller (hereinafter also referred to as "acid diffusion controller [C]"). The radiation-sensitive composition may also contain a polymer (hereinafter also referred to as "polymer [F]") having a higher fluorine atom content than the [P] polymer. The radiation-sensitive composition may contain other optional components within a range that does not impair the effects of the present invention.

[0018] The radiation-sensitive composition can be prepared, for example, by mixing the polymer (P), and, if necessary, the acid generator (B), the acid diffusion controller (C), the organic solvent (D), and the polymer (F) 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.

[0019] Each component contained in the radiation-sensitive composition will be described below.

[0020] <Polymer [P]> The polymer [P] is a polymer having a structural unit A including a partial structure in which a hydrogen atom of a carboxy group is substituted with an acid-dissociable group represented by formula (z) described below (acid-dissociable group (z)).

[0021] The radiation-sensitive composition may contain one or more types of polymers (P).

[0022] The polymer (P) preferably has a structural unit B containing a phenolic hydroxyl group.

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

[0024] The other structural units are structural units other than the structural units A and B. Examples of the other structural units include structural units containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof, and structural units containing a group that generates an acid when exposed to radiation.

[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 [P] 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 [P], as measured by gel permeation chromatography (GPC) in terms of polystyrene, is preferably 1,000, more preferably 2,000, even more preferably 3,000, and still more preferably 4,000. The upper limit of the Mw is preferably 30,000, more preferably 20,000, even more preferably 10,000, and still more preferably 7,000. By setting the Mw of the polymer [P] within the above range, the coatability of the radiation-sensitive composition can be improved. The Mw of the polymer [P] can be adjusted, for example, by adjusting the type and amount of polymerization initiator used in the synthesis of the polymer [P].

[0028] The upper limit of the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (P) 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 (P) can be synthesized, for example, by polymerizing monomers that provide the respective structural units by a known method.

[0031] Hereinafter, each structural unit contained in the polymer (P) will be described.

[0032] [Structural Unit A] The structural unit A is a structural unit containing a partial structure in which a hydrogen atom of a carboxy group is substituted with an acid-dissociable group (z) represented by the formula (z) described below. The "acid-dissociable group" refers to a group that substitutes a hydrogen atom of a carboxy group and dissociates under the action of an acid to give a carboxy group.

[0033] The acid-dissociable group (z) is a group that substitutes a hydrogen atom of the carboxy group in the structural unit A. In other words, in the structural unit A, the acid-dissociable group (z) is bonded to the etheric oxygen atom of the carbonyloxy group.

[0034] The [P] polymer exhibits a property in which its solubility in a developer changes due to the action of an acid, since the structural unit A contains an acid-dissociable group (z). The acid-dissociable group (z) is dissociated by the action of an acid generated from the radiation-sensitive acid-generating component in response to the action of radiation, and this causes a difference in the solubility of the [P] polymer in a developer between the exposed and unexposed areas, thereby enabling the formation of a resist pattern.

[0035] The acid-dissociable group (z) is a group represented by the following formula (z).

[0036]

[0037] In the above formula (z), R １ is a group obtained by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic heterocycle. １ is a group obtained by removing (n+1) hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring. X is an iodo group or a bromo group. n is an integer of 1 or more. * indicates the bonding site with the etheric oxygen atom of the carboxy group.

[0038] R １ The number of ring members in the aliphatic heterocycle giving the formula (I) is preferably 3 to 30, more preferably 4 to 20, still more preferably 4 to 10, and particularly preferably 4 to 6. 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 a condensed polycycle in which two rings have two shared atoms, but also a ring assembly type polycycle in which two rings do not have a shared atom and are connected by a single bond.

[0039] R １ The heteroatom constituting the aliphatic heterocycle giving the formula (I) is preferably an oxygen atom, a sulfur atom, a nitrogen atom or a combination thereof, more preferably an oxygen atom, a sulfur atom or a combination thereof.

[0040] R １ As the aliphatic heterocycle giving R, a monocyclic aliphatic heterocycle is preferred. １ When is a monocyclic aliphatic heterocycle, the solubility in a developer tends to be improved and the occurrence of development defects tends to be further suppressed.

[0041] R １ Among the aliphatic heterocycles which give the formula (I), examples of monocyclic aliphatic heterocycles include oxygen atom-containing heterocycles such as an oxacyclopropane ring, an oxacyclobutane ring, an oxacyclopentane ring, and an oxacyclohexane ring; sulfur atom-containing heterocycles such as a thiacyclopropane ring, a thiacyclobutane ring, a thiacyclopentane ring, a thiacyclohexane ring, a thiacyclohexane-1-oxide ring, a thiacyclopentane-1,1-dioxide ring, and a thiacyclohexane-1,1-dioxide ring; and nitrogen atom-containing heterocycles such as an azacyclopropane ring, an azacyclobutane ring, an azacyclopentane ring, and an azacyclohexane ring.

[0042] R １ Examples of the substituent that the aliphatic heterocycle giving the formula (I) may have 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.

[0043] R １ Preferably, the aliphatic heterocycle giving R １ The aliphatic heterocycle giving the formula (I) is preferably an unsubstituted aliphatic heterocycle.

[0044] Ar １ The number of ring members in the aromatic hydrocarbon ring giving the formula (I) is preferably 6 to 30, more preferably 6 to 20, and even more preferably 6 to 10.

[0045] Ar １ Examples of aromatic hydrocarbon rings which 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.

[0046] Ar １ The aromatic hydrocarbon ring that gives the following formula is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

[0047] Ar １ Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include a halogeno group other than an iodo group or a bromo group (e.g., a fluoro group), a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group.

[0048] X may be an iodo group or a bromo group. When X is an iodo group, sensitivity can be further improved.

[0049] n is preferably 1 to 3, and more preferably 1 or 2. When n is 2, there is a tendency that the sensitivity and CDU can be further improved.

[0050] R in the above formula (z) １ is preferably a group represented by the following formula (rz):

[0051]

[0052] In the above formula (rz), Q is —O—, —S—, —SO ２ -, -SO- or -NR Ａ - is. R Ａ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. １ and n ２ are each independently an integer of 0 to 5. １ +n ２is 1 or more. * has the same meaning as in formula (z) above. *1 is Ar in formula (z) above. １ The binding site is shown.

[0053] Q is -O-, -S-, -SO ２ When Q is —O—, —S— or —SO—, the CDU tends to be further improved. ２ When it is — or —SO—, the occurrence of development defects tends to be further suppressed.

[0054] n １ As the number, 1 to 3 is preferred, and 1 or 2 is more preferred.

[0055] n ２ As the number, 1 to 3 is preferred, and 1 or 2 is more preferred.

[0056] n １ +n ２ is preferably 2 to 6, more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 2 or 3. １ +n ２ When is 2 or 3, the sensitivity and CDU tend to be further improved.

[0057] Examples of the acid-dissociable group (z) include groups represented by the following formulae (z-1) to (z-10).

[0058]

[0059] In the above formulas (z-1) to (z-10), * has the same meaning as in the above formula (z).

[0060] Examples of the structural unit A include a structural unit represented by the following formula (A).

[0061]

[0062] In the above formula (A), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, —O—, —COO— or —CONH—. ２is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. Z is the acid-dissociable group (z) described above. L １ is —O—, —COO— or —CONH—, Ar ２ is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring.

[0063] R ２ From the viewpoint of copolymerizability of the monomer that gives the structural unit A, a hydrogen atom or a methyl group is preferred.

[0064] L １ is preferably a single bond.

[0065] Ar ２ The aromatic hydrocarbon ring giving the formula (I) preferably has 6 to 30 ring members, more preferably 6 to 20 ring members.

[0066] Ar ２ Examples of aromatic hydrocarbon rings that give the formula include the above-mentioned Ar １ Examples of aromatic hydrocarbon rings that give the following formula include those given above. ２ The aromatic hydrocarbon ring giving the formula (I) is preferably a benzene ring or a naphthalene ring.

[0067] Ar ２ Examples of the substituents that the aromatic hydrocarbon ring may have include the above-mentioned Ar １ Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include the groups exemplified above.

[0068] Specific examples of the structure of the monomer that provides the structural unit A include the monomers (A-1) to (A-10) in the examples described below.

[0069] The lower limit of the content of the structural unit A in the polymer [P] is preferably 20 mol %, more preferably 30 mol %, and even more preferably 40 mol %, based on the total structural units constituting the polymer [P].The upper limit of the content is preferably 80 mol %, more preferably 70 mol %, and even more preferably 60 mol %.

[0070] [Structural Unit B] The structural unit B 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.

[0071] In the case of KrF exposure, EUV exposure, or electron beam exposure, the sensitivity of the radiation-sensitive composition can be further increased by the polymer [P] containing the structural unit B. Therefore, the radiation-sensitive composition can be suitably used as a radiation-sensitive composition for KrF exposure, EUV exposure, or electron beam exposure.

[0072] Examples of the structural unit B include a structural unit represented by the following formula (II).

[0073]

[0074] In the above formula (II), R Ｐ is 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.

[0075] R Ｐ From the viewpoint of copolymerizability of the monomer that gives the structural unit B, a hydrogen atom or a methyl group is preferred.

[0076] L Ｐ is preferably a single bond or *-COO-.

[0077] Ar Ｐ The aromatic hydrocarbon ring giving the formula (I) preferably has 6 to 30 ring members, more preferably 6 to 20 ring members.

[0078] Ar Ｐ Examples of aromatic hydrocarbon rings that give the formula include the above-mentioned Ar １ Examples of aromatic hydrocarbon rings which give the following rings include those given as examples.

[0079] Ar ＰExamples of the substituents that the aromatic hydrocarbon ring may have include the above-mentioned Ar １ Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include the groups exemplified above.

[0080] As p, 1 or 2 is preferred.

[0081] Examples of the structural unit B include structural units represented by the following formulae (II-1) to (II-20).

[0082]

[0083] In the above formulas (II-1) to (II-20), R Ｐ has the same meaning as in formula (II) above.

[0084] Specific examples of the structure of the monomer that provides the structural unit B include the monomers (M-1) to (M-8) in the examples described below.

[0085] The lower limit of the content of the structural unit B in the polymer [P] is preferably 20 mol %, more preferably 30 mol %, based on all structural units constituting the polymer [P].The upper limit of the content is preferably 70 mol %, more preferably 60 mol %.

[0086] [Other structural units] The other structural units are structural units other than the structural units A and B. Examples of the other structural units include 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 C"), and a structural unit containing a group that generates an acid when acted upon by radiation (hereinafter also referred to as "structural unit D").

[0087] (Structural Unit C) The structural unit C is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. When the polymer (P) further contains the structural unit C, the adhesion to the substrate can be improved.

[0088] Examples of the structural unit C include structural units represented by the following formula:

[0089]

[0090]

[0091]

[0092]

[0093] In the above formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0094] The structural unit C is preferably a structural unit containing a lactone structure.

[0095] Specific examples of the structure of the monomer that provides the structural unit C include the monomers (M-9) and (M-10) in the examples described below.

[0096] When the polymer [P] contains the structural unit C, the lower limit of the content of the structural unit C is preferably 1 mol %, more preferably 5 mol %, based on the total structural units constituting the polymer [P]. The upper limit of the content is preferably 30 mol %, more preferably 20 mol %.

[0097] (Structural Unit D) The structural unit D is a structural unit containing a group that generates an acid when exposed to radiation. 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> described below.

[0098] 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. Such groups are classified into a structure in which an anion is bonded to a side chain of a polymer (hereinafter also referred to as "Structure 1") and a structure in which a radiation-sensitive onium cation is bonded to a side chain of a polymer (hereinafter also referred to as "Structure 2"). The group that generates an acid when acted upon by radiation may be Structure 1 or Structure 2.

[0099] Examples of the group that generates a sulfonic acid upon the action of radiation include groups represented by the following formula (x):

[0100]

[0101] 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. ａ１ is 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 a fluoro group or a fluorinated hydrocarbon 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 a binding site.

[0102] "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".

[0103] 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.

[0104] Examples of aliphatic hydrocarbon rings having 5 or more ring members include monocyclic saturated alicyclic rings such as a cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclononane ring, cyclodecane ring, and cyclododecane ring; monocyclic unsaturated alicyclic rings such as a cyclopentene ring, cyclohexene ring, cycloheptene ring, cyclooctene ring, and cyclodecene ring; polycyclic saturated alicyclic rings such as a norbornane ring, adamantane ring, tricyclodecane ring, tetracyclododecane ring, and steroid structure; and polycyclic unsaturated alicyclic rings such as a norbornene ring and tricyclodecene ring. The term "steroid structure" refers to a structure having a basic skeleton (sterane skeleton) in which three 6-membered rings and one 5-membered ring are fused.

[0105] Examples of the aliphatic heterocyclic ring having 5 or more ring members include lactone rings such as a hexanolactone ring and a norbornanelactone ring; sultone rings such as a hexanosultone ring and a norbornanesultone ring; dioxolane ring, oxacycloheptane ring, oxanorbornane ring, 3,5-dioxatricyclo[5.2.1.0 ２，６ ] Examples of heterocycles include an oxygen atom-containing heterocycle such as a decane ring; a nitrogen atom-containing heterocycle such as an azacyclohexane ring or a diazabicyclooctane ring; and a sulfur atom-containing heterocycle such as a thiacyclohexane ring or a thianorbornane ring.

[0106] Examples of aromatic hydrocarbon rings having 6 or more ring members include the above-mentioned Ar １ Examples of aromatic hydrocarbon rings which give the following rings include those given as examples.

[0107] Examples of aromatic heterocycles having 5 or more ring members include oxygen atom-containing heterocycles such as a furan ring, a pyran ring, a benzofuran ring, and a benzopyran ring; nitrogen atom-containing heterocycles such as a pyridine ring, a pyrimidine ring, and an indole ring; and sulfur atom-containing heterocycles such as a thiophene ring.

[0108] The ring structure is preferably an aromatic hydrocarbon ring, more preferably a benzene ring.

[0109] 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. １Examples of the substituent that the aromatic hydrocarbon ring that gives the formula (I) may have include the groups exemplified above.

[0110] 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.

[0111] n ａ１ is preferably 0 or 1.

[0112] R ａ２ and R ａ３ Examples of the hydrocarbon group that gives Ｙ , R Ｚ , R Ａ , or R Ｂ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the following formula are given below.

[0113] 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 Ｙ , R Ｚ , R Ａ , or R Ｂ Examples of the substituent that may be possessed by the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the following formula include those exemplified above.

[0114] R ａ２ and R ａ３ is preferably a hydrogen atom.

[0115] n ａ２ is preferably 0 to 5, and more preferably 0 or 1.

[0116] The term "fluorinated hydrocarbon group" refers to a hydrocarbon group in which at least one hydrogen atom has been substituted with a fluorine atom.

[0117] Examples of the hydrocarbon group that gives the fluorinated hydrocarbon group include the above-mentioned R ａ２ and R ａ３ Examples of hydrocarbon groups that give the following formula include those given above.

[0118] The fluorinated hydrocarbon group is preferably a fluorinated alkyl group, more preferably a perfluoroalkyl group, and even more preferably a trifluoromethyl group.

[0119] n ａ３ is preferably 1 to 5, and more preferably 1 or 2.

[0120] 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.

[0121] Examples of the monovalent radiation-sensitive onium cation include monovalent cations represented by the following formulas (r-a) to (r-c) (hereinafter also referred to as "cations (r-a) to (r-c)").

[0122]

[0123] 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, R Ｂ２ 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 RＢ４ 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.

[0124] In the above formula (r-b), b4 is an integer of 0 to 9. When b4 is 1, R Ｂ６ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ６ 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 Ｂ６ 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. b5 is an integer of 0 to 10. When b5 is 1, R Ｂ７ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ７ 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 Ｂ７ are combined with each other to form a ring structure having 3 to 20 ring members together with the carbon atoms or carbon chains to which they are attached. ｂ３ is an integer from 0 to 3. Ｂ８ is a single bond or a divalent linking group. ｂ２ is an integer from 0 to 2.

[0125] 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. Ｂ１０ 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 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.

[0126] "Organic group" refers to a group containing at least one carbon atom.

[0127] R Ｂ１ , R Ｂ２ , R Ｂ３ , R Ｂ４ , R Ｂ５ , R Ｂ６ , R Ｂ７ , R Ｂ９ or R Ｂ１０ Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group containing a divalent heteroatom-containing group between the carbon-carbon bonds of this hydrocarbon group (hereinafter also referred to as "group (β1)"), a group in which some or all of the hydrogen atoms in the hydrocarbon group or the group (β1) have been substituted with a monovalent heteroatom-containing group (hereinafter also referred to as "group (β2)"), and a group in which the hydrocarbon group, the group (β1) or the group (β2) is combined with a divalent heteroatom-containing group (hereinafter also referred to as "group (β3)").

[0128] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the above-mentioned R Ｙ , R Ｚ , R Ａ , or R ＢExamples of the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the following formula are given below.

[0129] Examples of heteroatoms constituting the monovalent or divalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, and halogen atoms.

[0130] Examples of the monovalent heteroatom-containing group include a halogeno group, a hydroxy group, a carboxy group, a cyano group, an amino group, a sulfanyl group (-SH), and an oxo group (=O).

[0131] Examples of divalent heteroatom-containing groups include -O-, -CO-, -S-, -CS-, -NR'-, and groups combining two or more of these (for example, -COO-, -CONR'-, etc.). R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R' include those having 1 to 10 carbon atoms among the groups exemplified above as the "monovalent hydrocarbon group having 1 to 20 carbon atoms".

[0132] R Ｂ８ Examples of the divalent organic group represented by the formula (I) include those in which one hydrogen atom has been removed from the above monovalent organic group.

[0133] R Ｂ１ , R Ｂ２ , R Ｂ５ , R Ｂ６ , 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.

[0134] R Ｂ３ and R Ｂ４ is preferably a hydrogen atom or a single bond formed by combining these, and is preferably a hydrogen atom.

[0135] 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 ｂ１is preferably 0 or 1.

[0136] The radiation-sensitive onium cation is preferably the cation (ra) or the cation (rc).

[0137] Examples of the cation (ra) include cations represented by the following formulae (ra-1) to (ra-17).

[0138]

[0139] Examples of the cation (r-c) include cations represented by the following formulae (r-c-1) to (r-c-4).

[0140]

[0141] A specific example of the structure of the monomer that provides the structural unit D is the monomer (M-11) in the examples described below.

[0142] When the polymer [P] contains the structural unit D, the lower limit of the content of the structural unit D in the polymer [P] is preferably 1 mol %, more preferably 5 mol %, based on all structural units constituting the polymer [P].The upper limit of the content is preferably 30 mol %, more preferably 20 mol %.

[0143] <[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 the like to generate carboxyl groups, which results in a difference in the solubility of the resist film in a developer between exposed and unexposed areas, thereby forming a resist pattern.

[0144] Examples of the acid generated from the acid generator (B) include sulfonic acids, carboxylic acids, and imide acids.

[0145] 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.

[0146] Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

[0147] Specific examples of the acid generator (B) include the compounds described in paragraphs

[0080] to

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

[0148] 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.

[0149] 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 (P)>.

[0150] 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.

[0151] 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.

[0152] Specific examples of the structure of the acid generator [B] include the acid generators (B-1) to (B-9) in the examples described later.

[0153] The lower limit of the content of the acid generator (B) in the radiation-sensitive composition is preferably 10 parts by mass and more preferably 20 parts by mass, relative to 100 parts by mass of the polymer (P), and the upper limit of the content is preferably 60 parts by mass and more preferably 50 parts by mass.

[0154] <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).

[0155] 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").

[0156] 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.

[0157] The photodegradable base generates a weak acid in the exposed area to increase the solubility or insolubility of the polymer (P) 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.

[0158] Examples of the radiation-sensitive onium cation in the photodegradable base include the radiation-sensitive onium cations described above in the section <Polymer (P)>.

[0159] 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.

[0160] 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.

[0161] Specific examples of the structure of the acid diffusion controller [C] include the acid diffusion controllers (C-1) to (C-9) in the examples described later.

[0162] 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 0.5 mol %, more preferably 1 mol %, and even more preferably 5 mol %, relative to 100 mol % of the radiation-sensitive acid generator (or the total amount of the radiation-sensitive acid generators, if multiple radiation-sensitive acid generators are present). The upper limit of the content is preferably 100 mol %, more preferably 50 mol %, and even more preferably 20 mol %.

[0163] <[D] Organic Solvent> The radiation-sensitive composition usually 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 [P], the acid generator [B], the acid diffusion controller [C], the polymer [F], and other optional components that may be contained as needed.

[0164] 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).

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane and n-hexane; and aromatic hydrocarbon solvents such as toluene and xylene.

[0171]

[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.

[0172] 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 %.

[0173] <[F] Polymer> The [F] polymer is a polymer different from the [P] polymer and has a higher fluorine atom content than the [P] polymer. Typically, polymers that are more hydrophobic than the base polymer tend to be unevenly distributed in the surface layer of the resist film. The [F] polymer has a higher fluorine atom content than the [P] polymer, and thus tends to be unevenly distributed in the surface layer of the resist film due to its hydrophobic properties. As a result, when the radiation-sensitive composition contains the [F] polymer, the cross-sectional shape of the formed resist pattern is expected to be excellent.

[0174] The form in which fluorine atoms are contained in the polymer [F] is not particularly limited, and they may be bonded to either the main chain or the side chain of the polymer [F]. Regarding the form in which fluorine atoms are contained in the polymer [F], it is preferable that the polymer [F] has a structural unit containing a fluorine atom (hereinafter also referred to as "structural unit F"). Specific examples of monomers that provide the structural unit F include monomers (M-13) and (M-14) in the examples described below.

[0175] The polymer [F] may further include a structural unit other than the structural unit F. Examples of the structural unit other than the structural unit F include a structural unit containing an acid-dissociable group. The polymer [F] may include one or more types of each structural unit.

[0176] When the radiation-sensitive composition contains the polymer [F], the lower limit of the content of the polymer [F] is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, relative to 100 parts by mass of the polymer [P], and the upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass.

[0177] <Other Optional Components> Examples of other optional components include surfactants, etc. The radiation-sensitive composition may contain one or more other optional components.

[0178] <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").

[0179] 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 CDU and suppressing the occurrence of development defects can be formed.

[0180] Each step of the resist pattern forming method will be described below.

[0181] [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.

[0182] In this step, the radiation-sensitive composition described above is used as the radiation-sensitive composition.

[0183] Substrates include, for example, silicon wafers, silicon dioxide, and aluminum coated wafers.

[0184] 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.

[0185] [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.

[0186] 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.

[0187] [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.

[0188] 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.

[0189] 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.

[0190] <Polymer> The polymer is the polymer (P) described above. The polymer can be suitably used as a base resin for a radiation-sensitive composition.

[0191] The polymer is described above in the section entitled "Polymer (P)."

[0192] Specific structures of the polymer include, for example, polymers (P-1) to (P-23) in the examples described below.

[0193] <Monomer> The monomer is a monomer represented by the following formula (ma): This monomer can be suitably used as a monomer for synthesizing a base resin of a radiation-sensitive composition.

[0194]

[0195] In the above formula (ma), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, —O—, —COO— or —CONH—. ２is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. Z is an acid-dissociable group represented by the following formula (z).

[0196] R in the above formula (ma) ２ , L １ , Ar ２ and Z have the same meanings as in formula (A) above.

[0197] Specific examples of the synthesis method of the monomer include the methods described in Synthesis Examples 1-1 to 1-10 in the Examples below.

[0198] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0199] <Synthesis of Monomer [A]> Compounds represented by the following formulae (A-1) to (A-10) and (cA-1) to (cA-3) (hereinafter also referred to as "monomers (A-1) to (A-10) and (cA-1) to (cA-3)") were synthesized according to the following method.

[0200]

[0201] [Synthesis Example 1-1] Synthesis of Monomer (A-1) Monomer (A-1) was synthesized according to the following synthesis scheme.

[0202]

[0203] 1,4-Diiodobenzene (30 mmol) and tetrahydrofuran (THF; 100 mL) were added to a reaction vessel, which was then cooled to -10°C. A 1.3 M isopropyl magnesium chloride-lithium chloride complex solution (iPrMgCl.LiCl; 25 mmol) was added, followed by the addition of tetrahydro-4H-pyran-4-one, and the mixture was stirred at room temperature for 2 hours. A saturated aqueous ammonium chloride solution was then added to the reaction solution, and ethyl acetate was added for extraction. The resulting organic layer was washed with water and dried over sodium sulfate. The solvent was then distilled off, and the residue was purified by column chromatography to obtain a compound represented by formula (A-1-a) (hereinafter also referred to as "compound (A-1-a)").

[0204] A reaction vessel was charged with compound (A-1-a) (20 mmol), triethylamine (Et３ N,N-dimethylaminopyridine (DMAP; 1.0 mmol) and dichloromethane (70 mL) were added, cooled to 0°C, methacryloyl chloride (24 mmol) was added, and the mixture was stirred at room temperature for 5 hours. Thereafter, a saturated aqueous ammonium chloride solution was added to the reaction solution, and then ethyl acetate was added for extraction. The obtained organic layer was washed with water and dried over sodium sulfate. Thereafter, the solvent was distilled off, and the mixture was purified by column chromatography to obtain monomer (A-1).

[0205] [Synthesis Example 1-2] Synthesis of Monomer (A-2) Monomer (A-1) was synthesized according to the following synthesis scheme.

[0206]

[0207] 1,4-Diiodobenzene (30 mmol) and tetrahydrofuran (THF; 100 mL) were added to a reaction vessel, which was then cooled to -10°C. A 1.3 M isopropyl magnesium chloride-lithium chloride complex solution (iPrMgCl.LiCl; 25 mmol) was added, followed by the addition of tetrahydrofuran-3-one, and the mixture was stirred at room temperature for 2 hours. A saturated aqueous ammonium chloride solution was then added to the reaction solution, and ethyl acetate was added for extraction. The resulting organic layer was washed with water and dried over sodium sulfate. The solvent was then distilled off, and the residue was purified by column chromatography to obtain a compound represented by the above formula (A-2-a) (hereinafter also referred to as "compound (A-2-a)").

[0208] 4-Vinylbenzoic acid (20 mmol), 1,1'-carbonyldiimidazole (CDI; 21 mmol), and dichloromethane (70 mL) were added to a reaction vessel and stirred, and then 1,8-diazabicyclo[5.4.0]-7-undecene (DBU; 30 mmol) and compound (A-2-a) (20 mmol) were added and stirred at room temperature for 3 hours. Thereafter, a saturated aqueous ammonium chloride solution was added to the reaction solution, and then ethyl acetate was added for extraction. The resulting organic layer was washed with water and dried over sodium sulfate. Thereafter, the solvent was distilled off, and the resulting mixture was purified by column chromatography to obtain monomer (A-2).

[0209] [Synthesis Examples 1-3 to 1-13] Monomers (A-3) to (A-10) and (cA-1) to (cA-3) were synthesized in the same manner as in Synthesis Example 1-1 or Synthesis Example 1-2, except that the synthetic raw materials and precursors of monomers (A-3) to (A-10) and (cA-1) to (cA-3) were appropriately changed.

[0210] <Synthesis of [P] Polymers> [Synthesis Examples 2-1 to 2-26] Synthesis of Polymers (P-1) to (P-23) and (cP-1) to (cP-3) The monomers were combined according to the compositions shown in Table 1 below, and copolymerization was carried out in a solvent of propylene glycol monomethyl ether (200 parts by mass relative to the total amount of monomers). The cooled polymerization solution was poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was separated by filtration. The separated white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, then separated by filtration, and dissolved in 1-methoxy-2-propanol (300 parts by mass). The resin was coagulated by dropping the mixture into 500 parts by mass of water, and the resulting solid was separated by filtration. The mixture was dried at 50°C for 12 hours to obtain white powdery polymers (P-1) to (P-23) and (cP-1) to (cP-3). The synthesis of the polymer [P] used monomers (A-1) to (A-10) and (cA-1) to (cA-3), and compounds represented by the following formulae (M-1) to (M-11) (hereinafter also referred to as "monomers (M-1) to (M-21)"). The composition of the obtained polymer [P] was analyzed using a nuclear magnetic resonance spectrometer ("JNM-Delta400" manufactured by JEOL Ltd.). １ The Mw and dispersity (Mw / Mn) were confirmed by H-NMR, and by GPC as described in the above section [Method for measuring Mw and Mn].

[0211]

[0212] In Table 1 below, "-" indicates that the corresponding monomer was not used. Furthermore, although monomers (cA-1) to (cA-3) do not correspond to monomers that provide structural unit A, they are listed in the column "Monomers that provide structural unit A" for comparison.

[0213]

[0214] <Synthesis of Polymer [F]> [Synthesis Examples 3-1 to 3-2] Synthesis of Polymers (F-1) to (F-2) The monomers were combined according to the compositions shown in Table 2 below, and copolymerization reaction was carried out in a solvent of 2-butanone (200 parts by mass). After completion of the polymerization reaction, the polymer solution was cooled to 30°C or below with water. The solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This procedure was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, solutions of Polymers (F-1) to (F-2) were obtained in good yield. Compounds represented by the following formulas (M-12) to (M-14) (hereinafter also referred to as "monomers (M-12) to (M-14)") were used to synthesize Polymer [F]. The compositions of the obtained Polymer [F] were determined using the above-mentioned nuclear magnetic resonance spectrometer. １ The Mw and dispersity (Mw / Mn) were confirmed by H-NMR, and by GPC as described in the above section [Method for measuring Mw and Mn].

[0215]

[0216]

[0217] <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 [P] used is taken as 100 parts by mass.

[0218] [[B] Acid Generator] As the acid generator [B], compounds represented by the following formulas (B-1) to (B-9) (hereinafter also referred to as "acid generators (B-1) to (B-9)") were used.

[0219]

[0220] [[C] Acid Diffusion Controller] As the acid diffusion controller [C], compounds represented by the following formulas (C-1) to (C-9) (hereinafter also referred to as "acid diffusion controllers (C-1) to (C-9)") were used.

[0221]

[0222] [[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

[0223] Example 1 Preparation of Radiation-Sensitive Composition (R-1) 100 parts by mass of Polymer (P-1), 25 parts by mass of Acid Generator (B-1), 10 mol % of Acid Diffusion Controller (C-1) based on Acid Generator (B-1), 6 parts by mass of Polymer (F-1), 4,800 parts by mass of Organic Solvent (D-1), and 2,000 parts by mass of Organic Solvent (D-2) were mixed together. The resulting mixture was filtered through a membrane filter with a pore size of 0.2 μm to prepare Radiation-Sensitive Composition (R-1).

[0224] Examples 2 to 41 and Comparative Examples 1 to 3 Preparation of Radiation-Sensitive Compositions (R-2) to (R-41) and (cR-1) to (cR-3) Radiation-sensitive compositions (R-2) to (R-41) and (cR-1) to (cR-3) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 3 below were used.

[0225] In Table 3 below, "-" indicates that the corresponding component was not used. The content of the acid diffusion controller (C) refers to the molar ratio relative to the radiation-sensitive acid generator.

[0226]

[0227] <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 20-nm-thick underlayer film (AL412 (manufactured by Brewer Science)) was formed using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). After PB at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 30-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). The resist film was subjected to PEB at 100°C for 60 seconds. The wafer was then developed using a 2.38% by mass aqueous TMAH solution at 23°C for 30 seconds to form a positive-tone 50-nm-pitch, 25-nm-thick contact hole pattern.

[0228] <Evaluation> The sensitivity, CDU and number of development defects were evaluated according to the following methods. The results are shown in Table 4 below.

[0229] [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 better the result. The sensitivity was 40 mJ / cm ２ If it is less than 40 mJ / cm, it is rated as "A" (very good). ２ More than 43mJ / cm ２ The following cases are rated as "B" (good) and 43 mJ / cm ２ If it was over 100%, it was rated as "C" (poor).

[0230] [CDU] The resist pattern formed in the above section <Formation of Resist Pattern> was observed from above the pattern using a scanning electron microscope (Hitachi High-Tech Corporation's "CG-4100"). A total of 600 points of hole diameter variation were measured, and a 3 sigma value was calculated from the distribution of the measured values. The calculated 3 sigma value was taken as CDU (unit: nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, indicating a better result. CDU was evaluated as "A" (very good) when it was less than 2.5 nm, "B" (good) when it was 2.5 nm or more but 2.8 nm or less, and "C" (poor) when it was more than 2.8 nm.

[0231] [Number of Development Defects] The number of defects (pieces) for the resist patterns formed in the above section <Formation of Resist Pattern> was measured using a defect inspection device (KLA-Tencor's "KLA2810"). The measured defects were then classified into those determined to be derived from the resist film and foreign matter derived from the external environment. The number of development defects was evaluated as "A" (very good) when the number of defects determined to be derived from the resist film was less than 30, as "B" (good) when the number was 30 to 50, and as "C" (poor) when the number was more than 50.

[0232]

Claims

1. A radiation-sensitive composition containing a polymer having a structural unit A containing a partial structure in which a hydrogen atom of a carboxy group is substituted with an acid-dissociable group represented by the following formula (z): (In formula (z), R １ is a group obtained by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic heterocycle. １ is a group obtained by removing (n+1) hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring. X is an iodo group or a bromo group. n is an integer of 1 or more. * indicates the bonding site with the etheric oxygen atom of the carboxy group.

2. The radiation-sensitive resin composition according to claim 1, wherein the heteroatom constituting the aliphatic heterocycle is an oxygen atom, a sulfur atom, a nitrogen atom, or a combination thereof.

3. R ​​in the above formula (z) １ 2. The radiation-sensitive resin composition according to claim 1, wherein the formula (rz) is represented by the following formula: (In formula (rz), Q is —O—, —S—, —SO ２ -, -SO- or -NR Ａ - is. R Ａ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. １ and n ２ are each independently an integer of 0 to 5. １ +n ２ is 1 or more. * has the same meaning as in formula (z) above. *1 is Ar in formula (z) above. １ The binding site is shown.) 4. The radiation-sensitive resin composition according to claim 1, wherein the structural unit A is represented by the following formula (A): (In formula (A), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, —O—, —COO— or —CONH—. ２ is a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. Z is an acid-dissociable group represented by the above formula (z). L １ is —O—, —COO— or —CONH—, Ar ２ is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring.

5. A method for forming a resist pattern, comprising the steps of: applying the radiation-sensitive composition according to any one of claims 1 to 4 directly or indirectly to a substrate; exposing the resist film formed by the application; and developing the exposed resist film.

6. A polymer having a structural unit A containing a partial structure in which a hydrogen atom of a carboxy group is substituted with an acid-dissociable group represented by the following formula (z): (In formula (z), R １ is a group obtained by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic heterocycle. １ is a group obtained by removing (n+1) hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring. X is an iodo group or a bromo group. n is an integer of 1 or more. * indicates the bonding site with the etheric oxygen atom of the carboxy group.

7. A monomer represented by the following formula (ma): (In formula (ma), R ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, —O—, —COO— or —CONH—. ２ is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. Z is an acid-dissociable group represented by the following formula (z): (In formula (z), R １ is a group obtained by removing two hydrogen atoms bonded to one carbon atom from a substituted or unsubstituted aliphatic heterocycle. １ is a group obtained by removing (n+1) hydrogen atoms from a substituted or unsubstituted aromatic hydrocarbon ring. X is an iodo group or a bromo group. n is an integer of 1 or more. * indicates the bonding site with the etheric oxygen atom in the above formula (ma).

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