Radiation-sensitive composition, resist pattern formation method, and compound

Abstract

A radiation-sensitive composition containing: a polymer that undergoes a change in solubility in a developing solution when subjected to the action of an acid; and a compound represented by formula (1).

Description

Radiation-sensitive composition, method for forming resist pattern, and compound

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

[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 LWR (Line Width Roughness), defect suppression, storage stability, and the like.

[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, a method for forming a resist pattern, and a compound that are excellent in sensitivity, LWR, defect suppression ability, and storage stability.

[0008] The invention made to solve the above problems is a radiation-sensitive composition containing a polymer whose solubility in a developer changes under the action of an acid, and a compound represented by the following formula (1): (In formula (1), -COO － and -OH are Ar １ Ar is bonded to each of the adjacent carbon atoms constituting the group. １ is a group obtained by removing (n+m+2) hydrogen atoms from an aromatic hydrocarbon ring. X is -O- or -S-. n is an integer of 1 to 10. m is an integer of 0 to 10. However, n+m is 10 or less. When n is 1, R １ is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group. １ is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group, or a plurality of R １ are bonded to each other and X and Ar to which they are bonded １ When n is 2 or more, the plurality of X's may be the same or different, and the plurality of R's may be the same or different. １ are the same or different. ２ is a halogeno group, a hydroxy group, or a halogenated hydrocarbon group. When m is 2 or more, a plurality of R ２ are the same or different. ＋ is a monovalent radiation-sensitive onium cation having a halogeno group or a halogenated hydrocarbon 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 a compound represented by the above formula (1).

[0011] The radiation-sensitive composition of the present invention is excellent in sensitivity, LWR, defect suppression, and storage stability. According to the method for forming a resist pattern of the present invention, a resist pattern with good sensitivity and excellent LWR, defect suppression, and storage stability can be formed. The compound of the present invention can be suitably used as a component of a radiation-sensitive composition that is excellent in sensitivity, LWR, defect suppression, and storage stability. Therefore, these compounds can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

[0012] The radiation-sensitive composition, method of forming a resist pattern, and compound of the present invention will be described in detail below.

[0013] 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."

[0014] <Radiation-Sensitive Composition> The radiation-sensitive composition contains a polymer whose solubility in a developer changes under the action of an acid (hereinafter also referred to as “polymer [A]”) and a compound represented by formula (1) described below (hereinafter also referred to as “compound [Z]”).

[0015] The radiation-sensitive composition contains the polymer (A) and the compound (Z), and therefore has excellent sensitivity, LWR, defect suppression properties, and storage stability.

[0016] The reason why the radiation-sensitive composition having the above-described structure exhibits the above-described effects is not entirely clear, but it is presumed, for example, as follows. First, it is thought that the compound [Z] has a halogeno group or a halogenated hydrocarbon group in the cation moiety, which improves the efficiency of reaction with electrons generated by exposure, thereby resulting in excellent sensitivity. Second, it is thought that the compound [Z] has a specific anion structure, which gives it high polarity, and it also has appropriate basicity, which results in excellent LWR, defect suppression, and storage stability. For the above reasons, it is thought that the radiation-sensitive composition can achieve a good balance between sensitivity, LWR, defect suppression, and storage stability.

[0017] The radiation-sensitive composition usually contains an organic solvent (hereinafter also referred to as "organic solvent [D]"). The radiation-sensitive composition may contain a radiation-sensitive acid generator (hereinafter also referred to as "acid generator [B]"). The radiation-sensitive composition may contain other optional components as long as the effects of the present invention are not impaired.

[0018] The radiation-sensitive composition can be prepared, for example, by mixing the polymer (A) and the compound (Z), as well as the acid generator (B), the organic solvent (D), and other optional components, if necessary, in a predetermined ratio, and filtering the resulting mixture through a filter with a pore size of 0.20 μm or less.

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

[0020] <Polymer (A)> The polymer (A) is a polymer whose solubility in a developer changes under the action of an acid. The radiation-sensitive composition may contain one or more types of polymer (A).

[0021] The polymer [A] preferably has a structural unit containing an acid-dissociable group (hereinafter also referred to as "structural unit (I)"). The polymer [A] preferably has a structural unit containing a phenolic hydroxyl group (hereinafter also simply referred to as "structural unit (II)"). The polymer [A] may further have other structural units (hereinafter also simply referred to as "other structural units") other than the structural unit (I) and the structural unit (II). The polymer [A] can have one or more types of each structural unit.

[0022] 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.

[0023] 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, more preferably 2,000, even more preferably 3,000, and still more preferably 5,000. 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 [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].

[0024] 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 1.8. The lower limit of the ratio is usually 1.0, preferably 1.1, more preferably 1.2, and even more preferably 1.3.

[0025] [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", one "G3000HXL", and one "G4000HXL" 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

[0026] The polymer (A) can be synthesized, for example, by polymerizing monomers that provide the respective structural units by a known method.

[0027] Each structural unit contained in the polymer (A) will be described below.

[0028] [Structural Unit (I)] 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 and dissociates under the action of an acid to give a carboxy group. More specifically, the structural unit (I) is a structural unit containing a partial structure in which a hydrogen atom in a carboxy group is substituted with an acid-dissociable group.

[0029] The polymer (A) contains an acid-dissociable group, and thereby exhibits a property in which its solubility in a developer changes under the action of an acid. The acid-dissociable group is dissociated by the action of an acid generated from the acid generator (B) or the like upon exposure, resulting in a difference in the solubility of the polymer (A) in a developer between the exposed and unexposed areas, thereby forming a resist pattern.

[0030] The acid-dissociable group is a group that substitutes a hydrogen atom of the carboxy group in the structural unit (I). In other words, in the structural unit (I), the acid-dissociable group is bonded to the etheric oxygen atom of the carbonyloxy group.

[0031] Examples of the acid-dissociable group include groups represented by the following formulae (a-1) and (a-2) (hereinafter also referred to as "acid-dissociable groups (a-1) and (a-2)").

[0032]

[0033] In the above formulas (a-1) and (a-2), * indicates the bonding site with the etheric oxygen atom of the carboxy group.

[0034] In the above formula (a-1), R Ｘ R 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.

[0035] In the above formula (a-2), R Ａ is a hydrogen atom. Ｂ and R Ｃ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Ｄ is R Ａ , R Ｂ and R Ｃ are divalent hydrocarbon groups having 1 to 20 carbon atoms which, together with the three carbon atoms to which they are bonded, constitute an unsaturated alicyclic ring having 4 to 20 ring members.

[0036] "Number of carbon atoms" refers to the number of carbon atoms constituting the group. "Hydrocarbon group" includes "aliphatic hydrocarbon group" and "aromatic hydrocarbon group". "Aliphatic hydrocarbon group" includes "chain hydrocarbon group" and "alicyclic hydrocarbon group". From another perspective, "aliphatic hydrocarbon group" includes "saturated hydrocarbon group" and "unsaturated hydrocarbon group". "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. "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 structure and may contain a chain structure as part of it. "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.

[0037] The "number of ring members" refers to the number of atoms constituting the ring structure, and in the case of a polycyclic ring, it refers to the number of atoms constituting the polycyclic ring. "Polycyclic rings" include not only spiro-type polycyclic rings in which two rings share one shared atom and fused-type polycyclic rings in which two rings share two shared atoms, but also ring assembly-type polycyclic rings in which two rings do not share an atom and are connected by a single bond.

[0038] "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".

[0039] R Ｘ , R Ｙ , R Ｚ , R Ｂ , or R Ｃ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the formula (I) include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0040] R Ｘ Examples of the substituent that may be possessed by the hydrocarbon group represented by the formula (R) 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 alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group. Ｘ has an iodo group as a substituent, which is preferred because it tends to further improve the LWR of the radiation-sensitive composition.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] R Ｙ and R Ｚ Examples of the saturated alicyclic ring having 3 to 20 ring members formed by combining these together with the carbon atoms to which they are bonded include monocyclic saturated alicyclic rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring; and polycyclic saturated alicyclic rings such as a norbornane ring, an adamantane ring, a tricyclodecane ring, and a tetracyclododecane ring.

[0045] R Ｄ Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include groups in which one hydrogen atom has been removed from the groups exemplified above as the monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0046] R Ｄ And, R Ａ , R Ｂ and R Ｃ and three carbon atoms to which each of the carbon atoms is bonded, include, for example, monocyclic unsaturated alicyclic structures such as a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure, and polycyclic unsaturated alicyclic structures such as a norbornene structure.

[0047] R Ｙ and R Ｚ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R Ｙ and R ＺAs R, a chain hydrocarbon group is preferable, an alkyl group is preferable, and a methyl group is more preferable. Ｘ R is preferably a substituted or unsubstituted chain hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group, more preferably an unsubstituted alkyl group or a substituted or unsubstituted aryl group, and even more preferably a methyl group or an iodophenyl group. Ｘ is an aryl group substituted with an iodine atom, this is preferred because it tends to further improve the LWR of the radiation-sensitive composition.

[0048] 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 monocyclic saturated alicyclic ring or a polycyclic saturated alicyclic ring, and more preferably a cyclopentane ring, a cyclohexane ring, or an adamantane ring. Ｘ As the alkyl group, a substituted or unsubstituted chain hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group is preferable, an unsubstituted alkyl group or an unsubstituted aryl group is more preferable, and a methyl group, an ethyl group or a phenyl group is even more preferable.

[0049] R Ｂ is preferably a hydrogen atom.

[0050] R Ｃ As the alkyl group, a chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is even more preferable.

[0051] R Ｄ And, R Ａ , R Ｂ and R Ｃ The unsaturated alicyclic ring having 4 to 20 ring members constituted by each of the carbon atoms to which each of the carbon atoms is bonded is preferably a monocyclic unsaturated alicyclic ring, more preferably a cyclohexene ring.

[0052] Examples of the acid-dissociable group (a-1) include groups represented by the following formulae (a-1-1) to (a-1-6): Examples of the acid-dissociable group (a-2) include groups represented by the following formula (a-2-1):

[0053]

[0054] In the above formulas (a-1-1) to (a-1-6) and (a-2-1), * has the same meaning as in the above formulas (a-1) and (a-2).

[0055] Examples of the structural unit (I) include a structural unit represented by the following formula (I).

[0056] In the above formula (I), R Ｈ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｈ is a single bond, *-COO- or *-CONH-. * 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. Ｈ３ is the acid-dissociable group.

[0057] R Ｈ１ From the viewpoint of copolymerizability of the monomer that gives the structural unit (I), a hydrogen atom or a methyl group is preferred.

[0058] L Ｈ is preferably a single bond.

[0059] R Ｈ２ The aromatic hydrocarbon ring giving the formula (I) preferably has 6 to 30 ring members, more preferably 6 to 20 ring members.

[0060] R Ｈ２ Examples of aromatic hydrocarbon rings that give the formula (R) 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; a 9,10-ethanoanthracene ring; and a triptycene ring. Ｈ２ The aromatic hydrocarbon ring that gives the following is preferably a benzene ring.

[0061] R Ｈ２ Examples of the substituents that the aromatic hydrocarbon ring may have include the above-mentioned R Ｘ Examples of the substituent that the hydrocarbon group represented by the following formula may have include the groups exemplified above.

[0062] R Ｈ２ R may be a single bond or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring. Ｈ２ is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring, which is preferred because it tends to further improve the LWR of the radiation-sensitive composition.

[0063] The lower limit of the content of the structural unit (I) in the polymer [A] is preferably 20 mol%, more preferably 30 mol%, even more preferably 40 mol%, and particularly preferably 45 mol%, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 90 mol%, more preferably 85 mol%, and even more preferably 80 mol%.

[0064] [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.

[0065] In the case of KrF exposure, EUV exposure, or electron beam exposure, the sensitivity of the radiation-sensitive composition can be further increased when the polymer [A] contains the structural unit (II). Therefore, when the polymer [A] contains the structural unit (II), the radiation-sensitive composition can be suitably used as a radiation-sensitive composition for KrF exposure, EUV exposure, or electron beam exposure.

[0066] Examples of the structural unit (II) include a structural unit represented by the following formula (II).

[0067]

[0068] In the above formula (II), R Ｐ is a hydrogen atom, a fluorine atom, 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.

[0069] R Ｐ As the alkyl group, a hydrogen atom or a methyl group is preferred from the viewpoint of copolymerizability of the monomer that gives the structural unit (II).

[0070] L Ｐ is preferably a single bond or *-COO-.

[0071] Ar Ｐ The aromatic hydrocarbon ring giving the formula (I) preferably has 6 to 30 ring members, more preferably 6 to 20 ring members.

[0072] Ar Ｐ Examples of the aromatic hydrocarbon ring that gives Ｈ２ Examples of aromatic hydrocarbon rings that give the following formula include those given above. Ｐ The aromatic hydrocarbon ring that gives the following formula is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

[0073] Ar Ｐ Examples of the substituents that the aromatic hydrocarbon ring may have include the above-mentioned R Ｘ Examples of the substituent that the hydrocarbon group represented by the following formula may have include the groups exemplified above.

[0074] p is preferably 1 or 2, and more preferably 1.

[0075] Examples of the structural unit (II) include structural units represented by the following formulae (II-1) to (II-18).

[0076]

[0077] In the above formulas (II-1) to (II-18), R Ｐ has the same meaning as in formula (II) above.

[0078] When the polymer [A] contains the structural unit (II), 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], and the upper limit of the content is preferably 70 mol %, more preferably 60 mol %.

[0079] Examples of monomers that provide the structural unit (II) include monomers in which the hydrogen atom of a phenolic hydroxyl group (—OH) is substituted with an acetyl group, such as 4-acetoxystyrene and 3,5-diacetoxystyrene. In this case, for example, the above-mentioned monomers can be polymerized, and then the resulting polymerization product can be hydrolyzed in the presence of a base such as an amine, thereby synthesizing the polymer [A] having the structural unit (II).

[0080] [Other structural units] The other structural units are structural units other than the structural units (I) and (II). 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 (III)"), a structural unit containing an alcoholic hydroxyl group (hereinafter also referred to as "structural unit (IV)"), and a structural unit containing a group that generates sulfonic acid when exposed to radiation (hereinafter also referred to as "structural unit (V)").

[0081] The structural unit contained in the polymer (A) may be considered to overlap with the classification of two or more structural units. For example, the polymer may include not only the structural unit (III) but also a structural unit considered to be a structural unit other than the structural unit (III). In this specification, such a structural unit is considered to be the structural unit with the lower number in parentheses.

[0082] (Structural Unit (III)) The structural unit (III) 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 (III), adhesion to the substrate can be improved. Furthermore, when the polymer [A] further contains the structural unit (III), the LWR of the radiation-sensitive composition tends to be further improved.

[0083] Examples of the structural unit (III) include structural units represented by the following formula:

[0084]

[0085]

[0086]

[0087]

[0088] In the above formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0089] The structural unit (III) is preferably a structural unit containing a lactone structure.

[0090] When the polymer [A] contains the structural unit (III), the lower limit of the content of the structural unit (III) 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 20 mol %, more preferably 10 mol %.

[0091] (Structural Unit (IV)) The structural unit (IV) is a structural unit containing an alcoholic hydroxyl group. When the polymer [A] further contains the structural unit (IV), the solubility in a developer can be more appropriately adjusted. Furthermore, when the polymer [A] further contains the structural unit (IV), the LWR of the radiation-sensitive composition tends to be further improved.

[0092] Examples of the structural unit (IV) include structural units represented by the following formula:

[0093]

[0094] In the above formula, R Ｌ２ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0095] When the polymer [A] has the structural unit (IV), the lower limit of the content of the structural unit (IV) is preferably 1 mol %, more preferably 5 mol %, based on all structural units constituting the polymer [A].The upper limit of the content is preferably 20 mol %, more preferably 10 mol %.

[0096] (Structural Unit (V)) The structural unit (V) is a structural unit containing a group that generates a sulfonic acid when exposed to radiation. When the polymer [A] contains the structural unit (V), the polymer [A] acts as a radiation-sensitive acid generator in the radiation-sensitive composition. When the polymer [A] further contains the structural unit (V), the LWR of the radiation-sensitive composition tends to be further improved.

[0097] Examples of the group that generates sulfonic acid upon the action of radiation include a group containing a sulfonate anion and a radiation-sensitive onium cation. Such groups are classified into a structure in which a sulfonate 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"). As the structural unit (V), Structure 1 is preferred. In the case of Structure 1, the diffusion of sulfonic acid generated by exposure is more controlled, which tends to further improve LWR.

[0098] Examples of the radiation include those exemplified as radiation in the section <Method of forming a resist pattern> below.

[0099] When the group capable of generating a sulfonic acid upon the action of radiation corresponds to the above structure 1, examples of the structural unit (V) include structural units represented by the following formula (V).

[0100]

[0101] In the above formula (V), R Ｐ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｐ１ is a single bond or *-COO-. * is R Ｐ１ indicates the bonding site with the carbon atom to which R is attached. Ｐ２ is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted ring structure. Ｐ１ is 0 or 1. Ｐ２ is a single bond or a divalent linking group. Ｐ３ and R Ｐ４ are each independently a hydrogen atom, a fluoro group, an alkyl group having 1 to 10 carbon atoms, or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms.Ｐ２ is an integer from 0 to 10. Ｐ２ If there are two or more R Ｐ３ are the same or different, and multiple R Ｐ４ are the same or different. Ｐ５ and R Ｐ６ are each independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. Ｐ３ is an integer from 1 to 10. Ｐ３ If there are two or more R Ｐ５ are the same or different, and multiple R Ｐ６ are the same or different. ＋ is a monovalent radiation-sensitive onium cation.

[0102] R Ｐ１ From the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred.

[0103] R Ｐ２ The number of ring members in the ring structure giving the formula (I) is preferably 5 to 30, and more preferably 6 to 30.

[0104] R Ｐ２ Examples of the ring structure that gives the above formula include an aliphatic hydrocarbon ring, an aliphatic heterocyclic ring, an aromatic hydrocarbon ring, and an aromatic heterocyclic ring.

[0105] Examples of the aliphatic hydrocarbon ring include monocyclic saturated alicyclic rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a cyclononane ring, a cyclodecane ring, and a cyclododecane ring; monocyclic unsaturated alicyclic rings such as a cyclopentene ring, a cyclohexene ring, a cycloheptene ring, a cyclooctene ring, and a cyclodecene ring; polycyclic saturated alicyclic rings such as a norbornane ring, an adamantane ring, a tricyclodecane ring, a tetracyclododecane ring, and a steroid structure; and polycyclic unsaturated alicyclic rings such as a norbornene ring and a tricyclodecene ring. The term "steroid structure" refers to a structure having a basic skeleton (sterane skeleton) in which three six-membered rings and one five-membered ring are fused.

[0106] Examples of the aliphatic heterocycle include lactone rings such as a hexanolactone ring and a norbornanelactone ring; sultone rings such as a hexanosultone ring and a norbornanesultone ring; oxygen atom-containing heterocycles such as an oxetane ring, a tetrahydrofuran ring, a dioxolane ring, an oxacycloheptane ring and an oxanorbornane ring; nitrogen atom-containing heterocycles such as an azacyclohexane ring and a diazabicyclooctane ring; and sulfur atom-containing heterocycles such as a thiacyclohexane ring and a thianorbornane ring.

[0107] Examples of the aromatic hydrocarbon ring 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; a 9,10-ethanoanthracene ring; and a triptycene ring.

[0108] Examples of the aromatic heterocycle 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.

[0109] R Ｐ２ The ring structure giving the formula (I) is preferably an aromatic ring, more preferably an aromatic hydrocarbon ring, and even more preferably a benzene ring.

[0110] R Ｐ２ Examples of the substituents that may be possessed by the ring structure that gives the formula include the above-mentioned R Ｘ Examples of the substituent that the hydrocarbon group represented by the following formula may have include the groups exemplified above.

[0111] n Ｐ１ As the number, 1 is preferred.

[0112] L Ｐ２ is preferably a divalent linking group.

[0113] The term "linking group" refers to a group that links two or more structures. The linking group remains in the structure of a compound or polymer due to reasons such as the synthetic materials or synthetic methods, and does not affect the effects of the present invention, or has an extremely small effect on the effects of the present invention. However, this does not mean that all structures other than the linking group contribute to the exertion of the effects of the present invention.

[0114] Examples of the divalent linking group include L Ｐ２ is not particularly limited as long as it is a group that connects two structures to which the bond is made, 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.

[0115] R Ｐ３ and R Ｐ４ Examples of the alkyl group having 1 to 10 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, and a propyl group.

[0116] The term "fluorinated alkyl group" refers to an alkyl group in which all or some of the hydrogen atoms have been substituted with fluoro groups.

[0117] R Ｐ３ , R Ｐ４ , R Ｐ５ or R Ｐ６ Examples of the fluorinated alkyl group having 1 to 10 carbon atoms represented by the formula (I) include perfluoroalkyl groups such as trifluoromethyl groups.

[0118] R Ｐ３ and R Ｐ４ is preferably a hydrogen atom.

[0119] R Ｐ５ and R Ｐ６ As the group, a fluoro group or a perfluoroalkyl group is preferred, and a fluoro group or a trifluoromethyl group is more preferred.

[0120] n Ｐ２ is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0121] n Ｐ３ As the number, 1 to 5 is preferred, 1 to 3 is more preferred, and 1 or 2 is even more preferred.

[0122] M ＋ The monovalent radiation-sensitive onium cation represented by the formula (I) is not particularly limited as long as it is known as a radiation-sensitive onium cation in an onium salt used as a radiation-sensitive acid generator contained in a radiation-sensitive composition. For example, a sulfonium cation (S ＋ ), iodonium cation (I ＋ ) are listed.

[0123] M ＋ Examples of the monovalent radiation-sensitive onium cation represented by the formula (r-a) include monovalent cations represented by the following formulas (r-a) to (r-c) (hereinafter, also referred to as "cations (r-a) to (r-c)").

[0124]

[0125] 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 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 Ｂ４are 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.

[0126] 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.

[0127] 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. Ｂ９are 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.

[0128] "Organic group" refers to a group containing at least one carbon atom.

[0129] 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)").

[0130] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the above-mentioned R Ｘ , R Ｙ , R Ｚ , R Ｂ , or R Ｃ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the following formula are given below.

[0131] Examples of heteroatoms constituting the monovalent or divalent heteroatom-containing group include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Halogen atoms are fluorine, chlorine, bromine, and iodine atoms.

[0132] 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).

[0133] Examples of the divalent heteroatom-containing group include —O—, —CO—, —S—, and —SO ２ Examples of such groups include -, -CS-, -NR'-, and groups formed by combining two or more of these groups (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".

[0134] R Ｂ８ Examples of the divalent organic group represented by the formula (I) include groups in which one hydrogen atom has been removed from the above monovalent organic groups.

[0135] R Ｂ１ , R Ｂ２ , R Ｂ５ , R Ｂ６ , R Ｂ９ and R Ｂ１０ is preferably a group (β2), a group (β3), or a halogeno group, more preferably a perfluoroalkyl group, an alkoxy group, an alkylsulfonyl group, a fluoro group, or an iodo group, and even more preferably a trifluoromethyl group, a methoxy group, a methanesulfonyl group, a fluoro group, or an iodo group. When it is an iodo group, the sensitivity of the radiation-sensitive composition tends to be further improved. Furthermore, when the number of halogen atoms in the cation moiety is 5 or more, the sensitivity of the radiation-sensitive composition tends to be further improved.

[0136] R Ｂ３ and R Ｂ４ is preferably a hydrogen atom or a single bond formed by combining these atoms together. Ｂ３and R Ｂ４ are preferably combined with each other to form a polycyclic sulfur atom-containing aromatic heterocycle together with the sulfur atom to which they are bonded.

[0137] 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.

[0138] The radiation-sensitive onium cation is preferably the cation (r-a) or the cation (r-c), and more preferably the cation (r-a). When the cation is the cation (r-a), the storage stability of the radiation-sensitive composition tends to be further improved compared to when the cation is the cation (r-c).

[0139] Examples of the cation (r-a) include cations represented by the following formulas (r-a-1) to (r-a-11) (hereinafter also referred to as "cations (r-a-1) to (r-a-11)"). Examples of the cation (r-c) include cations represented by the following formula (r-c-1) (hereinafter also referred to as "cation (r-c-1)").

[0140]

[0141] Examples of the structural unit (V) include structural units represented by the following formula:

[0142]

[0143] In the above formula, R Ｐ１ and M ＋ has the same meaning as formula (V) above.

[0144] When the polymer [A] contains the structural unit (V), the lower limit of the content of the structural unit (V) 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 20 mol %, more preferably 15 mol %.

[0145] <[B] Acid Generator> The [B] acid generator is a substance that generates an acid upon exposure. Examples of radiation used for exposure include those exemplified as radiation in the section <Method of Forming a Resist Pattern> described below. The acid generated upon exposure dissociates acid-dissociable groups, etc., of the polymer (A) to generate 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.

[0146] The radiation-sensitive composition may or may not contain an acid generator (B). When the radiation-sensitive composition does not contain an acid generator (B), it is preferable that the polymer (A) has a structural unit (V). In other words, it is preferable that the radiation-sensitive composition contains a component having a structure that generates an acid upon exposure.

[0147] Examples of the acid generated from the acid generator (B) include sulfonic acid, carboxylic acid, and imide acid.

[0148] 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.

[0149] Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts.

[0150] Specific examples of the acid generator (B) include the compounds described in paragraphs

[0080] to

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

[0151] 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.

[0152] Examples of the acid generator (B) that generates a sulfonic acid upon exposure include compounds represented by the following formula (2).

[0153]

[0154] In the above formula (2), R Ｐ７ is a group in which one hydrogen atom has been removed from a substituted or unsubstituted ring structure. Ｐ２ , R Ｐ３ , R Ｐ４ , R Ｐ５ , R Ｐ６ , n Ｐ２ , n Ｐ３ and M ＋ has the same meaning as formula (V) above.

[0155] R Ｐ７ The number of ring members in the ring structure giving the formula (I) is preferably 5 to 30, and more preferably 6 to 30.

[0156] R Ｐ７ Examples of the ring structure that gives ｐ２ Examples of ring structures that give the following ring structures are given below.

[0157] R Ｐ７ Examples of the substituents that may be possessed by the ring structure that gives the formula include the above-mentioned R Ｘ Examples of the substituent that the hydrocarbon group represented by the formula (I) may have include groups that are exemplified above and groups that contain an acid-dissociable group. Ｐ７ When the ring structure giving R has a carboxy group as a substituent, the LWR of the radiation-sensitive composition tends to be further improved. Ｐ７ When the ring structure that provides the formula (I) has a group containing an acid-dissociable group as a substituent (for example, —COOR when R is an acid-dissociable group), the LWR of the radiation-sensitive composition tends to be further improved.

[0158] Specific examples of the acid generator (B) that generates a sulfonic acid upon exposure include compounds represented by the following formulas (2-1) to (2-10).

[0159]

[0160] In the above formulas (2-1) to (2-10), M ＋ has the same meaning as formula (V) above.

[0161] 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.

[0162] The lower limit of the content of the acid generator (B) in the radiation-sensitive composition is preferably 1 part by mass, more preferably 5 parts by mass, and even more preferably 10 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, and even more preferably 30 parts by mass.

[0163] <[Z] Compound> In the radiation-sensitive composition, the [Z] compound acts as an acid diffusion controller (hereinafter also referred to as "[C] acid diffusion controller"). The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator or the like upon exposure, and thereby controls undesirable chemical reactions in unexposed areas. Note that the [Z] compound can also be called a radiation-sensitive acid generator in a broad sense because it generates acid upon the action of radiation. However, under conditions where the acid generated from the radiation-sensitive acid generator upon exposure dissociates an acid-dissociable group, the acid generated from the [Z] compound upon exposure does not dissociate the acid-dissociable group, and therefore the two are clearly distinguished.

[0164] The compound [Z] is a compound represented by the following formula (1). ＋ The portion represented by the formula (I) may be referred to as a “cation portion,” and the other portion may be referred to as an “anion portion.” The radiation-sensitive composition may contain one or more [Z] compounds.

[0165]

[0166] In the above formula (1), —COO － and -OH are Ar １ Ar is bonded to each of the adjacent carbon atoms constituting the group. １ is a group obtained by removing (n+m+2) hydrogen atoms from an aromatic hydrocarbon ring. X is -O- or -S-. n is an integer of 1 to 10. m is an integer of 0 to 10. However, n+m is 10 or less. When n is 1, R １is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group. １ is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group, or a plurality of R １ are bonded to each other and X and Ar to which they are bonded １ When n is 2 or more, the plurality of X's may be the same or different, and the plurality of R's may be the same or different. １ are the same or different. ２ is a halogeno group, a hydroxy group, or a halogenated hydrocarbon group. When m is 2 or more, a plurality of R ２ are the same or different. ＋ is a monovalent radiation-sensitive onium cation having a halogeno group or a halogenated hydrocarbon group.

[0167] Ar １ The aromatic hydrocarbon ring giving the formula (I) preferably has 6 to 30 ring members, more preferably 6 to 20 ring members.

[0168] Ar １ Examples of the aromatic hydrocarbon ring that gives Ｈ２ Examples of aromatic hydrocarbon rings that give the following formula include those given above. １ The aromatic hydrocarbon ring that gives the following is preferably a benzene ring.

[0169] X is preferably —O—.

[0170] R １ Examples of the saturated hydrocarbon group that gives the above formula include a chain saturated hydrocarbon group (alkyl group) and an alicyclic saturated hydrocarbon group.

[0171] Examples of the chain saturated hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group.

[0172] Examples of the alicyclic saturated hydrocarbon group include monocyclic alicyclic saturated hydrocarbon groups such as a cyclopentyl group and a cyclohexyl group; and polycyclic alicyclic saturated hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group.

[0173] R １ The saturated hydrocarbon group that provides the formula (I) is preferably a chain saturated hydrocarbon group (alkyl group). When the chain saturated hydrocarbon group (alkyl group) is used, the sensitivity and defect suppression ability of the radiation-sensitive composition tend to be more improved than when the chain saturated hydrocarbon group is used, as compared with when the chain saturated hydrocarbon group is used, such as an alicyclic saturated hydrocarbon group.

[0174] R when n is 1 １ As the alkyl group, an unsubstituted saturated hydrocarbon group or a substituted saturated hydrocarbon group substituted with a halogeno group or a hydroxy group is preferred, and an unsubstituted saturated hydrocarbon group or a substituted saturated hydrocarbon group substituted with a hydroxy group is more preferred. An unsubstituted saturated hydrocarbon group or a substituted saturated hydrocarbon group substituted with a hydroxy group tends to be able to further improve the sensitivity of the radiation-sensitive composition compared to a substituted saturated hydrocarbon group substituted with a halogeno group.

[0175] R １ The number of carbon atoms in R is, for example, 1 to 10, preferably 1 to 6, and more preferably 1 to 3. １ When the number of carbon atoms is 3 or less, the LWR of the radiation-sensitive composition tends to be more improved than when the number of carbon atoms is 4 or more.

[0176] n is preferably 1 to 3, more preferably 1 or 2, and most preferably 1.

[0177] When n is 2 or more, a plurality of R １ are bonded to each other and to the X and Ar １ The carbon atom may cooperate with the carbon atom to form an aliphatic heterocycle, for example, when X is —O—, a 1,3-dioxolane ring is included as the aliphatic heterocycle.

[0178] Ar １ When the aromatic hydrocarbon ring giving １ The group represented by -X- is -COO －It is preferably bonded to the —COO group at the para or meta position, more preferably at the para position. － and -OH are Ar １ This is the —COO － and —OH are in an ortho position to each other.

[0179] m is preferably 0 or 1, and when m is 1, R ２ is preferably a halogeno group or a hydroxy group, and m is more preferably 0.

[0180] A ＋ The halogeno group contained in the radiation-sensitive onium cation represented by the formula (I) is preferably a fluoro group. ＋ The halogenated hydrocarbon group contained in the radiation-sensitive onium cation represented by the formula (I) is preferably a fluorinated hydrocarbon group. In this case, the LWR of the radiation-sensitive composition tends to be further improved.

[0181] A ＋ The radiation-sensitive onium cation represented by the formula (I) preferably has a substituted aromatic ring in which at least one hydrogen atom on the aromatic ring is substituted with a halogeno group or a halogenated hydrocarbon group.

[0182] A ＋ Examples of the radiation-sensitive onium cation represented by the formula (I) include those having a halogeno group or a halogenated hydrocarbon group among the above-mentioned cations (r-a) to (r-c). ＋ Among the monovalent cations represented by the above formulae (r-a) to (r-c), the radiation-sensitive onium cation represented by R Ｂ１ , R Ｂ２ and R Ｂ５ At least one of R is a halogeno group or a halogenated hydrocarbon group, and in formula (r-b), at least one R Ｂ６ is a halogeno group or a halogenated hydrocarbon group, and in formula (r-c), R Ｂ９ and R Ｂ１０At least one of the groups is a halogeno group or a halogenated hydrocarbon group.

[0183] A ＋ As the radiation-sensitive onium cation represented by the formula (r-a), those having a halogeno group or a halogenated hydrocarbon group are preferred among the above-mentioned cations (r-a). In this case, the storage stability of the radiation-sensitive composition tends to be further improved compared to those of the (r-c) type. In particular, A is preferred in that it tends to further improve the sensitivity and storage stability of the radiation-sensitive composition. ＋ More preferably, b1 and b2 are those having a halogeno group at the meta position of the phenyl group. Ｂ１ and two R Ｂ２ are all halogeno groups, and two R Ｂ１ and two R Ｂ２ are all sulfonium cations bonded to the meta position.

[0184] A ＋ Specific examples of the radiation-sensitive onium cation represented by the formula (I) include the above-mentioned cations (r-a-2) to (r-a-9) and (r-c-1).

[0185] The molecular weight of the anion moiety of compound [Z] is preferably 245 or less, and more preferably 215 or less. When the molecular weight is 245 or less, the defect suppression ability of the radiation-sensitive composition tends to be further improved. When the molecular weight is 215 or less, the sensitivity of the radiation-sensitive composition tends to be further improved. The molecular weight of the anion moiety of compound [Z] is the molecular weight in the state of a carboxylate anion.

[0186] Examples of the compound [Z] include compounds represented by the following formulas (1-1) to (1-12).

[0187]

[0188] In the above formulas (1-1) to (1-12), A ＋ is synonymous with the above formula (1).

[0189] The compound (Z) may be a compound in which the above cation moiety and the above anion moiety are appropriately combined.

[0190] The lower limit of the content of the compound [Z] in the radiation-sensitive composition is preferably 5 mol %, more preferably 10 mol %, and even more preferably 20 mol %, based on the component having a structure that generates an acid upon exposure. The upper limit of the content is preferably 100 mol %, more preferably 60 mol %, and even more preferably 50 mol %. Examples of the "component having a structure that generates an acid upon exposure" include the polymer [A] (having the structural unit (V)) and the acid generator [B] described above.

[0191] <[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 [A] and the compound [Z], as well as the acid generator [B] and other optional components that may be contained as needed.

[0192] 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).

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane and n-hexane; and aromatic hydrocarbon solvents such as toluene and xylene.

[0199] 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 methyl 2-hydroxyisobutyrate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or a combination thereof.

[0200] 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 %.

[0201] <Other Optional Components> Examples of the other optional components include an acid diffusion controller (C) other than the compound (Z), a surfactant, etc. The radiation-sensitive composition may contain one or more other optional components.

[0202] <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").

[0203] 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 that exhibits excellent sensitivity, LWR, defect suppression, and storage stability can be formed.

[0204] Each step of the resist pattern forming method will be described below.

[0205] [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.

[0206] In this step, the radiation-sensitive composition described above is used as the radiation-sensitive composition.

[0207] Substrates include, for example, silicon wafers, silicon dioxide, and aluminum coated wafers.

[0208] 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.

[0209] [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.

[0210] 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.

[0211] [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.

[0212] 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.

[0213] 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.

[0214] <Compound> The compound is the compound [Z] described above. The compound can be suitably used as an acid diffusion controller for a radiation-sensitive composition. When the compound is used as an acid diffusion controller for a radiation-sensitive composition, the radiation-sensitive composition can have excellent sensitivity, LWR, defect suppression, and storage stability.

[0215] The compound may be, for example, a compound having a group R １ The compound can be synthesized by converting salicylic acid having --X-- into a sodium salt, followed by a salt exchange reaction with a salt consisting of a radiation-sensitive onium cation and a halogen ion.

[0216] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0217] <Synthesis of Compound [Z]> [Synthesis Example Z1] Synthesis of Acid Diffusion Controller (C-1) 4-Methoxysalicylic acid (4.20 mmol), sodium hydrogencarbonate (6.3 mmol), and ultrapure water (8.4 mL) were mixed and stirred at room temperature for 1 hour. Next, a compound represented by the following formula (S-1) (4.2 mmol) and dichloromethane (8.4 mL) were added, and the mixture was stirred for another 1 hour. After completion of the reaction, the aqueous layer was removed, and the resulting organic layer was washed with ultrapure water. The organic layer was dried over anhydrous sodium sulfate and filtered. The solvent was distilled off to obtain a compound represented by the following formula (C-1) (hereinafter also referred to as "acid diffusion controller (C-1)").

[0218]

[0219] [Synthesis Examples Z2 to Z28] Synthesis of acid diffusion controllers (C-2) to (C-20) and (XC-1) to (XC-8) Compounds represented by the following formulae (C-2) to (C-20) and (XC-1) to (XC-8) (hereinafter also referred to as "acid diffusion controllers (C-2) to (C-13) and (XC-1) to (XC-8)") were obtained in the same manner as in Synthesis Example Z1, except that the types of raw materials used in Synthesis Example Z1 were changed.

[0220]

[0221]

[0222]

[0223] The acid diffusion controllers (C-1) to (C-20) correspond to the above-mentioned compound [Z].

[0224] <Synthesis of Polymer [A]> Polymers (A-1) to (A-15) were synthesized according to the following method. Compounds represented by the following formulas (M-1) to (M-18) (hereinafter also referred to as "monomers (M-1) to (M-18)") were used to synthesize Polymer [A]. The Mw and Mw / Mn of the obtained Polymer [A] were confirmed by GPC as described in the above section [Method for measuring Mw and Mn].

[0225] In the following synthesis examples, unless otherwise specified, "parts by mass" means a value when the total mass of the monomers used is taken as 100 parts by mass, and "mol %" means a value when the total number of moles of the monomers used is taken as 100 mol %.

[0226]

[0227] Synthesis Example 1 Synthesis of Polymer (A-1) Monomer (M-1) and monomer (M-4) were dissolved in propylene glycol monomethyl ether (200 parts by mass relative to the total amount of monomers) so that the molar ratio in the final polymer [A] was 40 / 60. Next, azobisisobutyronitrile was added as an initiator in an amount of 6 mol % relative to the total amount of monomers to prepare a monomer solution. Meanwhile, propylene glycol monomethyl ether (100 parts by mass relative to the total amount of monomers) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for an additional 3 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature.

[0228] The cooled polymerization solution was poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass relative to the polymerization solution) and then dissolved in propylene glycol monomethyl ether (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was carried out at 70°C for 6 hours with stirring.

[0229] After completion of the hydrolysis reaction, the residual solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass). This solution was added dropwise to ultrapure water (500 parts by mass) to coagulate the resin, and the resulting solid was separated by filtration. The resulting solid was dried at 50°C for 12 hours to obtain a white powdery polymer (A-1). The Mw of the polymer (A-1) was 5,600, and the Mw / Mn was 1.5.

[0230] [Synthesis Examples 2 to 11 and 13] Synthesis of polymers (A-2) to (A-11) and (A-13) Polymers (A-2) to (A-11) and (A-13) were synthesized in the same manner as in Synthesis Example 1 above, except that the types and ratios of the monomers were changed as shown in Table 1 below.

[0231] Synthesis Example 12 Synthesis of Polymer (A-12) Monomer (M-18), monomer (M-4), and monomer (M-3) were dissolved in propylene glycol monomethyl ether (200 parts by mass relative to the total amount of monomers) so that the molar ratio in the final polymer [A] was 30 / 60 / 10. Next, azobisisobutyronitrile was added as an initiator in an amount of 6 mol% relative to the total amount of monomers to prepare a monomer solution. Meanwhile, propylene glycol monomethyl ether (100 parts by mass relative to the total amount of monomers) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for an additional 3 hours. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature.

[0232] The cooled polymerization solution was poured into hexane (500 parts by mass based on the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass based on the polymerization solution) and then dried at 50°C for 12 hours to obtain a white powdery polymer (A-12). The Mw of the polymer (A-12) was 6,600, and the Mw / Mn was 1.7.

[0233] [Synthesis Examples 14 and 15] Synthesis of polymers (A-14) and (A-15) Polymers (A-14) and (A-15) were synthesized in the same manner as in Synthesis Example 12, except that the types and ratios of the monomers were changed as shown in Table 1 below.

[0234] The types and ratios of monomers that provide each structural unit of Polymer [A] obtained in Synthesis Examples 1 to 15, as well as Mw and Mw / Mn, are shown in Table 1. In Table 1, "-" indicates that the corresponding monomer was not used.

[0235]

[0236] <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.

[0237] [[B] Acid Generator] As the acid generator [B], compounds represented by acid generators (B-1) to (B-11) (hereinafter also referred to as "acid generators (B-1) to (B-11)") were used.

[0238]

[0239] [[C] Acid Diffusion Controller] As the acid diffusion controller [C], the above-mentioned acid diffusion controllers (C-1) to (C-20) and (XC-1) to (XC-8) were used.

[0240] [[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): Methyl 2-hydroxyisobutyrate

[0241] Example 1 Preparation of Radiation-Sensitive Composition (R-1) [A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, [C] 20 mol % of (C-1) as an acid diffusion inhibitor relative to the acid generator (B-1), and [D] 4,800 parts by mass of (D-1) and 2,000 parts by mass of (D-2) as organic solvents were blended and mixed, and then filtered through a filter having a pore size of 0.20 μm to prepare a radiation-sensitive composition (R-1).

[0242] Examples 2 to 44 and Comparative Examples 1 to 8 Preparation of Radiation-Sensitive Compositions (R-2) to (R-44) and (CR-1) to (CR-8) Radiation-sensitive compositions (R-2) to (R-44) and (CR-1) to (CR-8) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 2 below were used.

[0243] In Table 2 below, "-" indicates that the corresponding component is not used.

[0244] In Table 2 below, the amount of the acid diffusion controller [C] refers to the molar ratio relative to the component having a radiation-sensitive acid-generating structure. Specifically, in Examples 13 to 15, the amount of the acid diffusion controller [C] refers to the molar ratio relative to the mass of the structural units derived from the monomers (M-15) to (M-17) contained in the polymer [A], while in Examples 1 to 12, 16 to 44 and Comparative Examples 1 to 8, the amount of the acid diffusion controller [C] refers to the molar ratio relative to the mass of the acid generator [B].

[0245]

[0246] <Resist Pattern Formation (1)> A resist pattern was formed according to the following method for evaluating the sensitivity, LWR, and defect suppression properties described below. The radiation-sensitive composition prepared above was applied to the surface of a 12-inch silicon wafer on which a 50-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 90°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 34 nm line and space pattern.

[0247] <Resist Pattern Formation (2)> A resist pattern was formed according to the following method for evaluating the storage stability described below. Using the spin coater described above, a radiation-sensitive composition from the group described below was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (DUV42 (Nissan Chemical Co., Ltd.)) had been formed. 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, the resist film was irradiated with KrF excimer laser light using a KrF exposure machine (Nikon Corporation's "S210D," NA = 0.55, illumination conditions: Annular s = 0.8, mask: 150 nm LS). The resist film was subjected to PEB at 90°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 150-nm line-and-space pattern.

[0248] <Evaluation> The sensitivity, LWR, defect suppression property and storage stability were evaluated according to the following methods. The results are shown in Table 3 below.

[0249] [Sensitivity] The exposure dose at which the resist pattern was formed in the above section <Formation of Resist Pattern (1)> was taken as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm ２ The sensitivity was 25 mJ / cm ２ In the following cases, the rating is "A" (good) and the rating is 25 mJ / cm ２ Super 30mJ / cm ２ In the following cases, the rating is "B" (fairly good) and 30 mJ / cm ２ If it was over 100%, it was rated as "C" (poor).

[0250] [LWR] The resist pattern formed in the above section <Formation of Resist Pattern (1)> was observed from above the pattern using a scanning electron microscope (Hitachi High-Tech Corporation's "CG-4100"). Line widths were measured at a total of 50 arbitrary points. A 3 sigma value was determined from the distribution of the measured values, and the determined 3 sigma value was taken as the LWR (unit: nm). The smaller the LWR value, the smaller the line wobble and the better the result. LWR was evaluated as "A" (good) when it was 4.0 nm or less, "B" (fairly good) when it was more than 4.0 nm and less than 4.5 nm, and "C" (poor) when it was more than 4.5 nm.

[0251] [Defect Suppression] The number of defects (number) was measured for the resist patterns formed in the above section <Formation of Resist Pattern (1)> using a defect inspection device (KLA-Tencor's "KLA2925"). The defect suppression was evaluated as "A" (good) when the number of defects was 20 or less, "B" (fairly good) when the number of defects was more than 20 but not more than 25, and "C" (poor) when the number of defects was more than 25.

[0252] [Storage Stability] After preparing the radiation-sensitive compositions, the compositions were divided into two groups: one group that had been stored at -15°C for two weeks and one group that had been stored at 35°C for two weeks. The optimal exposure dose for forming a 150 nm line and space pattern was determined in the above <Formation of Resist Pattern (2)>. When the rate of change (E2-E1) / E1 of the optimal exposure dose (E2) for the group that had been stored at 35°C for two weeks relative to the optimal exposure dose (E1) for the group that had been stored at -15°C for two weeks was less than ±0.7%, the composition was evaluated as "A" (good); when it was ±(less than 1.0%, 0.7% or more), the composition was evaluated as "B" (fairly good); and when it was ±1.0% or more, the composition was evaluated as "C" (poor).

[0253]

[0254] From Table 3, it can be seen that all of the radiation-sensitive compositions of the Examples were superior in sensitivity, LWR, defect suppression, and storage stability compared to the radiation-sensitive compositions of the Comparative Examples.

Claims

1. A radiation-sensitive composition comprising: a polymer whose solubility in a developer changes under the action of an acid; and a compound represented by the following formula (1): (In formula (1), -COO － and -OH are Ar １ Ar is bonded to each of the adjacent carbon atoms constituting the group. １ is a group obtained by removing (n+m+2) hydrogen atoms from an aromatic hydrocarbon ring. X is -O- or -S-. n is an integer of 1 to 10. m is an integer of 0 to 10. However, n+m is 10 or less. When n is 1, R １ is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group. １ is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group, or a plurality of R １ are bonded to each other and X and Ar １ When n is 2 or more, the plurality of X's may be the same or different, and the plurality of R's may be the same or different. １ are the same or different. ２ is a halogeno group, a hydroxy group, or a halogenated hydrocarbon group. When m is 2 or more, a plurality of R ２ are the same or different. ＋ is a monovalent radiation-sensitive onium cation having a halogeno group or a halogenated hydrocarbon group.

2. The radiation-sensitive composition according to claim 1, wherein X in the formula (1) is —O—.

3. R in the above formula (1) １ 2. The radiation-sensitive composition according to claim 1, wherein is an unsubstituted alkyl group or a substituted alkyl group substituted with a halogeno group, a hydroxy group, or an alkoxy group.

4. A in the above formula (1) ＋ 2. The radiation-sensitive composition according to claim 1, wherein at least one hydrogen atom on the aromatic ring is substituted with a halogeno group or a halogenated hydrocarbon group.

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 a resist film formed by said application; and developing the exposed resist film.

6. A compound represented by the following formula (1): (In formula (1), -COO － and -OH are Ar １ Ar is bonded to each of the adjacent carbon atoms constituting the group. １ is a group obtained by removing (n+m+2) hydrogen atoms from an aromatic hydrocarbon ring. X is -O- or -S-. n is an integer of 1 to 10. m is an integer of 0 to 10. However, n+m is 10 or less. When n is 1, R １ is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group. １ is an unsubstituted saturated hydrocarbon group, or a substituted saturated hydrocarbon group substituted with a halogeno group, a hydroxy group, or an alkoxy group, or a plurality of R １ are bonded to each other and X and Ar to which they are bonded １ Together with the carbon atom above, it forms an aliphatic heterocycle. When n is 2 or more, a plurality of Xs may be the same or different, and a plurality of R １ are the same or different. ２ is a halogeno group, a hydroxy group, or a halogenated hydrocarbon group. When m is 2 or more, a plurality of R ２ are the same or different. ＋ is a monovalent radiation-sensitive onium cation having a halogeno group or a halogenated hydrocarbon group.

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