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

Abstract

This radiation-sensitive composition contains a polymer including a structural unit represented by formula (1). In formula (1), L1 represents a single bond, *1-CO-O-, *1-CO-NH-, or -O-. L2 and L3 each independently represent a single bond or a divalent linking group. R3 represents a single bond or a substituted or unsubstituted alkanediyl group. A1 represents an aliphatic ring group or an aromatic ring group having a valence of (r3+3). A2 represents an aromatic ring group having a valence of (r1+r2+1). X1 represents a halogen atom or a halogenated alkyl group. R4 represents a monovalent substituent excluding a halogen atom and a halogenated alkyl group. R5 represents a monovalent substituent. r2 represents an integer of 1 or more. r1 and r3 each independently represent an integer of 0 or more. M+ represents a radiation-sensitive cation.

Description

Radiation-sensitive composition, method for forming a resist pattern, polymer, compound, and method for producing the compound.

[0001] [Cross-reference of related applications] This application claims priority under Japanese Patent Application No. 2025-56872, filed on 28 March 2025, which is incorporated herein by reference in its entirety. This disclosure relates to radiation-sensitive compositions, methods for forming resist patterns, polymers, compounds, and methods for producing compounds.

[0002] In lithography technology, which is used in the manufacturing processes of various electronic devices such as semiconductor devices and liquid crystal devices, a radiation-sensitive composition is irradiated with far ultraviolet light (such as an ArF excimer laser), extreme ultraviolet light (EUV), or an electron beam to generate acid in the exposed area. A chemical reaction involving this acid creates a difference in the dissolution rate in the developer between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] With the miniaturization of various electronic device structures, there is a demand for further miniaturization of resist patterns in lithography processes. In addition, in response to the demand for further miniaturization of resist patterns, various studies are being conducted to improve the resolution of radiation-sensitive compositions used in microfabrication by lithography and the shape of the resist patterns (see, for example, Patent Document 1). Patent Document 1 discloses the use of a monomer having an onium salt structure in which an aromatic hydrocarbon ring to which a group having a sulfonic acid anion is bonded is bonded via a -COO- to an aromatic hydrocarbon ring or aliphatic hydrocarbon ring to which a polymerizable group is bonded, and a polymer containing repeating units derived from this monomer is used as the base resin of the radiation-sensitive composition.

[0004] International Publication No. 2024 / 014462

[0005] In photolithography technology, pattern miniaturization has been promoted by using short-wavelength radiation such as ArF excimer laser, or by employing immersion lithography (liquid immersion lithography) in which exposure is performed with the space between the lens of an exposure apparatus and a resist film filled with a liquid medium. In addition, as next-generation technologies, development of lithography using shorter-wavelength radiation such as electron beams, X-rays, extreme ultraviolet (EUV), etc. is also in progress. In the efforts toward these next-generation technologies, it is required to reduce LWR (Line Width Roughness), which is an index representing the quality of resist patterns, and the number of development defects as much as possible.

[0006] The main object of the present disclosure is to provide a radiation-sensitive composition capable of obtaining a resist pattern with small LWR and few development defects. In addition, another object of the present disclosure is to provide a method for forming a resist pattern capable of obtaining a resist pattern with small LWR and few development defects.

[0007] According to the present disclosure, in one aspect, there is provided a radiation-sensitive composition containing a polymer including a structural unit represented by the following formula (1). (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L １ is a single bond, *-CO-O-, * １ -CO-NH- or -O-. * １ represents a bond to the carbon atom to which R １ is bonded. A １ is an (r3+3)-valent aromatic ring group or aliphatic cyclic group. L １ and L ２ are each independently a single bond or a divalent linking group. R ３ is a single bond, an alkanediyl group or a fluoroalkanediyl group. R ２ and R ｆ１ are each independently a hydrogen atom, a cyano group, a nitro group, a fluorine atom or a fluoroalkyl group. R ｆ２ is a single bond or a substituted or unsubstituted alkanediyl group. A ３ ２is an aromatic ring group with (r1 + r2 + 1) valency. １ R is a halogen atom or an alkyl halogen. ４ R is a monovalent substituent excluding halogen atoms and alkyl halides. ５ X is a monovalent substituent. r2 is an integer greater than or equal to 1. r1 and r3 are independent integers greater than or equal to 0. If r1 is 2 or greater, multiple X １ They are the same or different. If r2 is 2 or more, there are multiple R ４ They are the same or different. If r3 is 2 or more, there are multiple R ５ They are the same or different. M ＋ (It is a radiation-sensitive cation.)

[0008] According to this disclosure, in another embodiment, a method for forming a resist pattern is provided, comprising the steps of: forming a resist film on a substrate using the above-mentioned radiation-sensitive composition; exposing the resist film; and developing the exposed resist film.

[0009] In another embodiment of this disclosure, a polymer comprising a structural unit represented by formula (1) is provided. In yet another embodiment of this disclosure, a compound represented by formula (2) is provided. (In formula (2), R １ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, * １ -CO-O-, * １ It is -CO-NH- or -O-. １ " is R １ This represents the bond with the carbon atom to which it is bonded. A １ L is an aromatic ring group or aliphatic ring group with (r3+3) valency. ２ and L ３ These are, independently of each other, single or divalent linking groups. ２ R is a single bond, an alkanediyl group, or a fluoroalkanediyl group. ｆ１ and R ｆ２ These are, independently of each other, a hydrogen atom, a cyano group, a nitro group, a fluorine atom, or a fluoroalkyl group. ３A is a single bond or a substituted or unsubstituted alkanediyl group. ２ is an aromatic ring group with (r1 + r2 + 1) valency. １ R is a halogen atom or an alkyl halogen. ４ R is a monovalent substituent excluding halogen atoms and alkyl halides. ５ X is a monovalent substituent. r2 is an integer greater than or equal to 1. r1 and r3 are independent integers greater than or equal to 0. If r1 is 2 or greater, multiple X １ They are the same or different. If r2 is 2 or more, there are multiple R ４ They are the same or different. If r3 is 2 or more, there are multiple R ５ They are the same or different. M ＋ (It is a radiation-sensitive cation.)

[0010] According to the radiation-sensitive composition of this disclosure, a resist pattern with low LWR and few development defects can be obtained. Furthermore, according to the resist pattern formation method of this disclosure, since the radiation-sensitive composition of this disclosure is used, a resist pattern with low LWR and few development defects can be formed.

[0011] The following describes in detail matters related to the embodiments. In this specification, numerical ranges indicated using "~" include the numbers indicated before and after "~" as the lower and upper limits, respectively.

[0012] Herein, in this specification, "hydrocarbon group" means a group that includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also have a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may also contain a linear structure or an alicyclic hydrocarbon structure as part of it. "n-valent aromatic ring group" means an n-valent group obtained by removing n hydrogen atoms (where n is an integer of 1 or more) from the ring portion of an aromatic ring. "Aromatic ring" includes aromatic hydrocarbon rings and aromatic heterocycles. "n-valent aliphatic ring group" refers to an n-valent group obtained by removing n hydrogen atoms (where n is an integer greater than or equal to 1) from the ring portion of an aliphatic ring. "Aliphatic ring" includes aliphatic hydrocarbon rings and aliphatic heterocycles. "Organic group" refers to an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

[0013] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which consists of the longest chain of atoms. This "trunk" portion may contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the polymer's main chain. "Side chains" refer to the parts of a polymer that branch off from the "trunk." "Structural units" are units that primarily constitute the main chain structure, and are present in the main chain structure in groups of two or more. Structural units are typically monomeric units. "(Meth)acrylate" is a term that encompasses both "acrylate" and "methacrylate."

[0014] The notation "substituted or unsubstituted p-valent hydrocarbon group" (where p is an integer of 1 or more) encompasses both p-valent hydrocarbon groups (i.e., unsubstituted p-valent hydrocarbon groups) and groups obtained by removing p hydrogen atoms from the hydrocarbon structural portion of a substituted hydrocarbon group. Examples of substituted or unsubstituted p-valent hydrocarbon groups include alkyl groups and fluoroalkyl groups, which fall under the case where p=1, and alkanediyl groups and fluoroalkanediyl groups, which fall under the case where p=2. Of these, fluoroalkyl groups fall under the category of "substituted monovalent hydrocarbon group," and fluoroalkanediyl groups fall under the category of "substituted divalent hydrocarbon group." The same applies to other groups with "substituted or unsubstituted" attached.

[0015] <<Radiation-sensitive composition>> The radiation-sensitive composition of this disclosure (hereinafter also referred to as "this composition") contains a polymer comprising a structural unit represented by the following formula (1). Hereinafter, the structural unit represented by the following formula (1) will also be referred to as "structural unit (I)", and a polymer having a substructure represented by the following formula (1) will also be referred to as "polymer (P)". (In formula (1), R １ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, * １ -CO-O-, * １ It is -CO-NH- or -O-. １ R １ This represents the bond with the carbon atom to which it is bonded. A １ L is an aromatic ring group or aliphatic ring group with (r3+3) valency. ２ and L ３ These are, independently of each other, single or divalent linking groups. ２ R is a single bond, an alkanediyl group, or a fluoroalkanediyl group. ｆ１ and R ｆ２ These are, independently of each other, a hydrogen atom, a cyano group, a nitro group, a fluorine atom, or a fluoroalkyl group. ３ A is a single bond or a substituted or unsubstituted alkanediyl group. ２ is an aromatic ring group with (r1 + r2 + 1) valency. １ R is a halogen atom or an alkyl halogen.４ R is a monovalent substituent excluding halogen atoms and alkyl halides. ５ X is a monovalent substituent. r2 is an integer greater than or equal to 1. r1 and r3 are independent integers greater than or equal to 0. If r1 is 2 or greater, multiple X １ They are the same or different. If r2 is 2 or more, there are multiple R ４ They are the same or different. If r3 is 2 or more, there are multiple R ５ They are the same or different. M ＋ (It is a radiation-sensitive cation.)

[0016] <Polymer (P)> ・Structural unit (I) In the above formula (1), R １ From the viewpoint of copolymerizability, a hydrogen atom or a methyl group is preferred.

[0017] A １ If is an aromatic ring group with (r3+3) valency, A １ Aromatic ring groups with a (r3+3) valency represented by include groups obtained by removing (r3+3) hydrogen atoms from the ring portion of an aromatic hydrocarbon ring, and groups obtained by removing (r3+3) hydrogen atoms from the ring portion of an aromatic heterocycle. The aromatic hydrocarbon ring may be monocyclic or polycyclic, and examples include benzene rings, naphthalene rings, anthracene rings, phenanthrene rings, etc. Of these, benzene rings or naphthalene rings are preferred, and benzene rings are more preferred. The aromatic heterocycle may also be monocyclic or polycyclic, and examples include imidazole rings, pyridine rings, furan rings, thiophene rings, benzimidazole rings, carbazole rings, etc. From the viewpoint of ease of synthesis and sensitivity, A １ The aromatic ring group with a (r3+3) valency represented by is preferably a group obtained by removing (r3+3) hydrogen atoms from the ring portion of an aromatic hydrocarbon ring, and more preferably a group obtained by removing (r3+3) hydrogen atoms from the ring portion of a benzene ring, from the viewpoint of further enhancing the sensitivity of the radiation-sensitive composition and the LWR reduction effect.

[0018] A １ If is an aliphatic ring group with a (r3+3) value, then A １Examples of aliphatic ring groups with an (r³+3) valency represented by include groups obtained by removing (r³+3) hydrogen atoms from the ring portion of an aliphatic hydrocarbon ring or aliphatic heterocycle. The aliphatic hydrocarbon ring and aliphatic heterocycle may be monocyclic or polycyclic. In the case of polycyclic rings, the aliphatic hydrocarbon ring and aliphatic heterocycle may have a bridged structure, a fused ring structure, or a spirocycle structure. Specific examples of aliphatic hydrocarbon rings include cyclopentane rings, cyclohexane rings, cycloheptane rings, cyclooctane rings, cyclopentene rings, cyclohexene rings, cycloheptene rings, cyclooctene rings, norbornane rings, bicyclo[2.2.2]octane rings, norbornene rings, adamantane rings, tricyclodecane rings, tetracyclododecane rings, and the like. Specific examples of aliphatic heterocycles include piperidine rings, piperazine rings, tetrahydrofuran rings, tetrahydropyran rings, tetrahydrothiophene rings, acetal rings (for example, 1,3-dioxolane rings, 1,3-dioxane rings, 1,4-dioxane rings, and fused or heterocycles containing any of these ring structures). In terms of obtaining a radiation-sensitive composition with a higher LWR reduction effect, A １ The (r3+3) valency aliphatic ring group represented by is preferably a group obtained by removing (r3+3) hydrogen atoms from the ring portion of an aliphatic hydrocarbon ring, more preferably a group obtained by removing (r3+3) hydrogen atoms from the ring portion of a polycyclic aliphatic ring, and even more preferably a group obtained by removing (r3+3) hydrogen atoms from the ring portion of a polycyclic aliphatic hydrocarbon ring.

[0019] In terms of obtaining a highly sensitive radiation-sensitive composition with a higher LWR reduction effect, A １ The group is preferably one obtained by removing (r3+3) hydrogen atoms from the ring portion of an aromatic hydrocarbon ring or an aliphatic hydrocarbon ring, and more preferably one obtained by removing (r3+3) hydrogen atoms from the ring portion of a benzene ring or a polycyclic aliphatic hydrocarbon ring (preferably a norbornane ring or an adamantane ring).

[0020] A ２ Aromatic ring groups with a (r1 + r2 + 1) valency represented by include groups obtained by removing (r1 + r2 + 1) hydrogen atoms from the ring portion of an aromatic hydrocarbon ring or aromatic heterocycle. Of these, A ２However, if the group is obtained by removing (r1 + r2 + 1) hydrogen atoms from the ring portion of an aromatic hydrocarbon ring, it is preferable in that the sensitivity of the radiation-sensitive composition can be increased. Specific examples and preferred examples of aromatic hydrocarbon rings include A １ A ring similar to the one exemplified in the explanation for the case of an aromatic ring group with (r3+3) valency can be cited. １ When the compound is an aromatic heterocyclic group with (r3+3) valency, it is preferable in that it can further reduce development defects.

[0021] X １ If X is a halogen atom, １ Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. Of these, fluorine and iodine atoms are preferred, and iodine atoms are more preferred, in terms of being able to increase the sensitivity of the radiation-sensitive composition. １ If X is a halogenated alkyl group, １ Examples of halogenated alkyl groups include groups in which one or more hydrogen atoms in a linear or branched alkyl group having 1 to 10 carbon atoms are substituted with halogen atoms. １ The alkyl halogen has 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms.

[0022] R ４ This is a monovalent substituent excluding halogen atoms and alkyl halides. Examples of such substituents include C1-C6 alkyl groups, C1-C6 alkoxy groups, C1-C6 alkoxy halides, hydroxyl groups, carboxyl groups, *-CO-R, and *-S (=O). ２ -R, *-NH-S (=O) ２ -R, *-S (=O) ２ Examples include -NH-R, *-NH-CO-R, *-CO-O-R, *-CO-NH-R, cyano group, nitro group (where R is an alkyl group having 1 to 5 carbon atoms, and * represents a bond). R may be linear or branched. Specific examples of R include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, etc.

[0023] While sufficiently reducing the LWR of a resist pattern (that is, while exhibiting excellent LWR performance), in terms of ensuring the solubility of the polymer and sufficiently suppressing the occurrence of development defects, R in the above formula (1) ４ is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a halogenated alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a carboxy group, *-CO-R, *-S(=O) ２ -R, *-NH-S(=O) ２ -R, *-S(=O) ２ -NH-R, *-NH-CO-R, *-CO-O-R, *-CO-NH-R, is preferably at least one selected from the group consisting of a cyano group and a nitro group. Further, in terms of further improving the LWR performance and the effect of reducing development defects, R in the above formula (1) ４ is an alkoxy group having 1 to 6 carbon atoms, *-CO-R, *-S(=O) ２ -R, *-NH-S(=O) ２ -R, *-S(=O) ２ -NH-R, *-NH-CO-R, *-CO-O-R, *-CO-NH-R, preferably contains at least one selected from the group consisting of a cyano group and a nitro group, and more preferably contains at least one selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms, *-CO-R, *-S(=O) ２ -R and *-NH-S(=O) ２ -R.

[0024] R ５ is a monovalent substituent. R ５ Specific examples of the monovalent substituent represented by include R ４ and the groups exemplified as X １ the groups exemplified as.

[0025] L ２ and L ３ When at least one of is a divalent linking group, examples of the divalent linking group include -O-, -S-, -CO-, * ２ -CO-O-, * ２ -O-CO-, -NH-, * ２ -CO-NH-, * ２ -NH-CO-, -SO ２ -, * ２- (CH ２ ) ｒ Examples include -O-, substituted or unsubstituted divalent aliphatic heterocyclic groups, etc. * ２ is, A １ Represents a combination with L. ２ and L ３ In this context, a divalent aliphatic heterocyclic group is a divalent group obtained by removing two hydrogen atoms from the ring portion of an aliphatic heterocyclic ring. A specific example of an aliphatic heterocyclic ring is A １ A specific example of a ring similar to the one exemplified is when the aliphatic ring group has a (r3+3) value. The aliphatic ring group is preferably an oxygen-containing aliphatic heterocyclic group, and more preferably contains an acetal ring structure, in that it can sufficiently reduce the LWR.

[0026] In terms of ease of synthesis of monomers that provide structural units (I), availability of raw materials, and the ability to improve the LWR performance of radiation-sensitive compositions, L ２ and L ３ Each of these is * ２ -CO-O-, * ２ It is preferable that it be -O-CO- or -O-. Also, L ２ However, when the group is a substituted or unsubstituted divalent oxygen-containing aliphatic heterocyclic group, a radiation-sensitive composition with superior LWR performance can be obtained. ３ but* ２ -CO-O- or * ２ -O-CO- or -O-, and R in formula (1) above ４ When the compound contains an alkoxy group having 1 to 6 carbon atoms, it is preferable in that a radiation-sensitive composition exhibiting superior LWR performance can be obtained.

[0027] L relative to the aromatic ring ２ , L ３ The bonding position is not particularly limited. For example, A １ It contains a benzene ring, L ２ , L ３ When bonded to a benzene ring, L relative to the benzene ring ２ , L ３ The respective bond positions are L １ It may be in the ortho, meta, or para position relative to L. From the viewpoint of ease of synthesis of the monomer that gives structural unit (I),２ , L ３ When bonded to a benzene ring, L ２ , L ３ The bonding position is L １ It is preferable that the position be meta and para relative to A. １ It contains an aliphatic ring, L ２ , L ３ When L is attached to an aliphatic ring, ２ , L ３ Preferably, it is bonded to different carbon atoms that make up the aliphatic ring.

[0028] R ２ If R is an alkanediyl group, ２ Examples of alkanediyl groups represented by include linear or branched alkyl groups having 1 to 10 carbon atoms. Specific examples include methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, butane-1,3-diyl group, butane-2,3-diyl group, hexane-1,6-diyl, etc. ２ A specific example of a fluoroalkanediyl group is a group in which one or more hydrogen atoms in the above-mentioned alkanediyl group are substituted with fluorine atoms. ２ When the group is a fluoroalkanediyl group, it is preferable because it can enhance the LWR reduction effect of the resist pattern obtained using the radiation-sensitive composition.

[0029] R ｆ１ and R ｆ２ If at least one of the groups is a fluoroalkyl group, examples of fluoroalkyl groups include those in which one or more hydrogen atoms in a linear or branched alkyl group having 1 to 10 carbon atoms are replaced by fluorine atoms. Specific examples of these include the trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, and 1,1,1,3,3,3-hexafluoropropyl group. The fluoroalkyl group is preferably a linear or branched fluoroalkyl group having 1 to 3 carbon atoms, and more preferably a trifluoromethyl group. From the viewpoint of sensitivity, R ｆ１ and R ｆ２At least one of them is preferably a fluorine atom or a trifluoromethyl group. Also, R ｆ１ and R ｆ２ If at least one of them is a cyano group, it is preferable in that the effect of reducing development defects can be further enhanced.

[0030] R ３ R is a single bond or a substituted or unsubstituted alkanediyl group. ３ A specific example of a case where is an alkanediyl group is R ２ Examples of groups similar to those exemplified in the explanation include R. ３ If the group is a substituted alkanediyl group, examples of substituents include halogen atoms (fluorine, chlorine, bromine, iodine, etc.), hydroxyl groups, cyano groups, nitro groups, and alkoxy groups.

[0031] r1 is a non-negative integer. It is preferable that r1 be 1 or greater, and more preferably 2 or greater, in order to further enhance the LWR reduction effect. Furthermore, from the viewpoint of LWR reduction, if r1 is 1 or greater, X １ It is preferable that at least one of them is an iodine atom. Also, from the viewpoint of maintaining a good balance between LWR reduction and development defect suppression, r1 is preferably 1 to 6, and more preferably 1 to 4. In particular, A ２ When the ring constituting the is a benzene ring and r2 is 1 or more, the LWR reduction effect of the resist pattern obtained from the radiation-sensitive composition can be further enhanced. Also, when r1 is 2 or more, R in formula (1) above ４ When the compound contains an alkoxy group having 1 to 6 carbon atoms, it is preferable in that a radiation-sensitive composition exhibiting superior LWR performance can be obtained.

[0032] r2 is an integer greater than or equal to 1. From the viewpoint of achieving a good balance between the pattern's LWR reduction effect and the development defect suppression effect, r2 is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1 or 2. A ２ When the ring constituting the composition is a benzene ring, the LWR performance of the radiation-sensitive composition can be further improved.

[0033] M ＋Examples of radiosensitive cations represented by include radiodegradable onium cations containing at least one element selected from the group consisting of S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Specific examples of radiodegradable onium cations include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, and pyridinium cations. Among these, M ＋ The sulfonium cation or iodonium cation is preferred, and specific examples of these include cations represented by the following formulas (4) to (6). (In formula (4), R １ａ and R ２ａ These are either monovalent substituents independently of each other, or R １ａ and R ２ａ These elements, when combined with each other, represent single or divalent groups that link the rings they form. ３ａ R is a monovalent substituent. a1 and a2 are integers from 0 to 5, independently of each other. a3 is an integer from 0 to (2 × r + 5). r is 0 or 1. In formula (5), R ４ａ and R ５ａ These are independent monovalent substituents. a4 and a5 are independent integers from 0 to 5. In formula (6), a6 is an integer from 0 to 7. When a6 is 1, R ６ａ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen group. If a6 is 2 or more, multiple R ６ａ The R groups are identical or different, and are monovalent organic groups, hydroxyl groups, nitro groups, or halogen groups having 1 to 20 carbon atoms, or multiple R groups. ６ａ Two of these are combined with each other, and together with the carbon atoms they bond to, they represent a ring structure with 4 to 20 members. a7 is an integer from 0 to 6. When a7 is 1, R ７ａ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen group. If a7 is 2 or more, multiple R ７ａ These are identical or different monovalent organic groups, hydroxyl groups, nitro groups, or halogen groups having 1 to 20 carbon atoms, or multiple R groups. ７ａThis represents a ring structure with 3 to 20 members, where two of the members are combined with each other and bonded together with the carbon atoms. t1 is an integer from 0 to 3. ８ａ (This refers to a single bond or a divalent organic group having 1 to 20 carbon atoms. t2 is 0 or 1.)

[0034] In equations (4) and (5) above, R １ａ , R ２ａ , R ３ａ , R ４ａ and R ５ａ (Hereinafter referred to as “R １ａ ~R ５ａ Examples of monovalent substituents represented as (denoted as ) include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted cycloalkyloxy groups, ester groups, alkylsulfonyl groups, cycloalkylsulfonyl groups, hydroxyl groups, carboxyl groups, cyano groups, and nitro groups.

[0035] R １ａ ~R ５ａ The alkyl group represented by may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms. Of these, R １ａ ~R ５ａ The alkyl group represented by is preferably having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, an n-butyl group, or a t-butyl group. １ａ ~R ５ａ Specific examples of groups where the group is an alkoxy group include groups having the alkyl group exemplified above in the alkyl group portion constituting the alkoxy group. The alkoxy group is preferably a methoxy group, an ethoxy group, an n-propoxy group, or an n-butoxy group.

[0036] R １ａ ~R ５ａThe cycloalkyl group represented by may be monocyclic or polycyclic. Examples of monocyclic cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cyclooctyl groups. Examples of polycyclic cycloalkyl groups include norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. １ａ ~R ５ａ A specific example of a cycloalkyloxy group is a group having the cycloalkyl group exemplified above in the cycloalkyl portion constituting the cycloalkyloxy group. １ａ ~R ５ａ The cycloalkyloxy group represented is preferably a cyclopentyloxy group or a cyclohexyloxy group.

[0037] R １ａ ~R ５ａ If the compound has substituents, examples of substituents include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and alkoxy groups having 1 to 5 carbon atoms.

[0038] R １ａ ~R ５ａ When is an ester group (-COOR), the hydrocarbon portion (R) of the ester group can be a substituted or unsubstituted alkyl group or a substituted or unsubstituted cycloalkyl group as exemplified above. Of these, R １ａ ~R ５ａ If R is an ester group, １ａ ~R ５ａ The preferred group is a methoxycarbonyl group, an ethoxycarbonyl group, or an n-butoxycarbonyl group. １ａ ~R ５ａ When is an alkylsulfonyl group, the alkyl group portion constituting the alkylsulfonyl group can be the substituted or unsubstituted alkyl groups exemplified above. １ａ ~R ５ａ When is a cycloalkylsulfonyl group, the cycloalkyl group portion constituting the cycloalkylsulfonyl group can be the substituted or unsubstituted cycloalkyl groups exemplified above.

[0039] R １ａ and R ２ａ When these are combined to form a ring, and represent a divalent group that links the rings they form, the divalent groups include, for example, -COO-, -OCO-, -CO-, -O-, -SO-, and -SO ２ -, -S-, -C1-C3 alkanediyl group, -C2 or 3 alkenediyl group, -O-, -S-, -COO-, -OCO-, -CO-, -SO-, or -SO between the carbon-carbon bonds of an ethylene group ２ Examples include groups having -. Of these, R １ａ and R ２ａ Preferably, the bond is a single bond connecting the rings, or it forms an -O- or -S- bond.

[0040] a1, a2, and a3 are preferably integers between 0 and 2. １ａ , R ２ａ and R ３ａ At least one of these is preferably a fluorine atom, an iodine atom, or a trifluoromethyl group. a4 and a5 are each preferably integers from 0 to 2. R present in formula (5) ４ａ and R ５ａ Preferably, at least one of these is a fluorine atom, an iodine atom, or a trifluoromethyl group.

[0041] In the above formula (6), R ６ａ and R ７ａ As a monovalent organic group having 1 to 20 carbon atoms, the following are substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, -OR ｋ , -COOR ｋ , -O-CO-R ｋ , -O-R ｋｋ - COOR ｋ , -R ｋｋ -CO-R ｋ , -OSO ２ -R ｋ or -SO ２ -R ｋ Examples include: R ｋ R is a monovalent hydrocarbon group having 1 to 10 carbon atoms. ｋｋR is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms. Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include the same groups as those exemplified in formula (r-1) above. ６ａ and R ７ａ In this, the substituent that substitutes a hydrogen atom of the hydrocarbon group is the above R １ａ ~R ５ａ The substituents on the group represented by can be similar to those exemplified. ８ａ Examples of divalent organic groups represented by R ６ａ and R ７ａ Examples include groups obtained by removing one hydrogen atom from a monovalent organic group having 1 to 20 carbon atoms, as exemplified above.

[0042] R ６ａ and R ７ａ This includes, among the above, linear or branched monovalent alkyl groups, monovalent fluoroalkyl groups, monovalent aromatic hydrocarbon groups, and -OSO ２ -R ｋ or -SO ２ -R ｋ This is preferable. a6 is preferably an integer between 0 and 2, and more preferably 0 or 1. a7 is preferably an integer between 0 and 2, and more preferably 0 or 1. t2 is preferably 0. t1 is preferably 2 or 3.

[0043] Specific examples of radiation-sensitive onium cations include cations represented by the following formula. However, radiation-sensitive onium cations are not limited to the following specific examples.

[0044] The radiation-sensitive cation (M) in formula (1) above ＋ When the iodonium cation is present, the LWR performance of the radiation-sensitive composition can be further improved, which is preferable. ＋ When the group contains a sulfonyl group, it is preferable because it can further enhance the sensitivity of the radiation-sensitive composition and the LWR reduction effect. Examples of groups containing a sulfonyl group include alkyl sulfonyl groups and cycloalkyl sulfonyl groups.

[0045] Specific examples of structural units (I) include structural units represented by the following formula. However, structural units (I) are not limited to the following specific examples. ＋ " is a radiation-sensitive cation, and specific examples of such cations include those exemplified above. (In the formula, R １ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＋ (It is a radiation-sensitive cation.)

[0046] From the viewpoint of sufficiently obtaining the effect of increasing the sensitivity of the radiation-sensitive composition and improving the LWR performance, the content of structural units (I) in the polymer (P) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, relative to the total structural units constituting the polymer (P). Furthermore, from the viewpoint of ensuring that the radiation-sensitive composition exhibits good LWR performance, the content of structural units (I) is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less, relative to the total structural units constituting the polymer (P). By setting the content of structural units (I) within the above range, the effect of improving sensitivity and good LWR performance can be sufficiently obtained.

[0047] - Other structural unit polymers (P) may further contain structural units different from structural unit (I) (hereinafter also referred to as "other structural units"). Examples of other structural units include structural units (II) to (V) shown below. Structural unit (II): Structural unit having an acid-dissociable group Structural unit (III): Structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring Structural unit (IV): Structural unit having a lactone structure, a cyclic carbonate structure, a sultone structure, or a heterocyclic structure combining two or more of these Structural unit (V): Structural unit having an alcoholic hydroxyl group In this specification, structural units having a hydroxyl group bonded to an aromatic ring and an acid-dissociable group are classified as structural unit (II).

[0048] • Structural Unit (II) The acid-dissociable groups of structural unit (II) are groups that substitute for hydrogen atoms in acidic groups such as carboxyl groups and hydroxyl groups, and dissociate under the action of acid. By incorporating a polymer having acid-dissociable groups into this composition, the acid-dissociable groups dissociate due to the acid generated by exposure, creating acidic groups and changing the solubility of the polymer components in the developer. This allows for the imparting of good lithography properties (specifically, LWR performance and CDU (Critical Dimension Uniformity) performance) to this composition, enabling the formation of good resist patterns.

[0049] Structural unit (II) is not particularly limited as long as it has an acid-dissociable group. Examples of structural unit (II) include the structural unit represented by the following formula (7-1) (hereinafter also referred to as "structural unit (2A)"), the structural unit represented by the following formula (7-2) (hereinafter also referred to as "structural unit (2B)"), and the structural unit represented by the following formula (7-3) (hereinafter also referred to as "structural unit (2C)"). (In formula (7-1), R ７２ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ５ R is a divalent chain-like organic group or an alicyclic hydrocarbon group. ７３ R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ７４ and R ７５ These are, independently of each other, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic heterocyclic group, or R ７４ and R ７５ They are combined with each other R ７４ and R ７５ This represents an alicyclic hydrocarbon structure with 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded. However, R ７３ If R is a hydrogen atom, ７４ and R ７５ Either or both of them are independently a substituted or unsubstituted monovalent unsaturated hydrocarbon group, a monovalent aromatic heterocyclic group, or R ７４ and R ７５ They are combined with each other R ７４ and R７５ This represents an alicyclic unsaturated hydrocarbon structure with 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded. g1 is 0 or 1. In formula (7-2), R ７６ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ６ These are single bonds, -O-, -CO-, and * ５ -COO- or * ５ -CONH-. * ５ R represents a bond to the main chain. ７７ , R ７８ and R ７９ These are, independently of each other, a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxyhydrocarbon group having 1 to 20 carbon atoms. ３５ is a monovalent substituent. g2 is an integer from 0 to 4. In formula (7-3), R ３１ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ７ These are single bonds, -O-, -CO-, and * ６ -COO- or * ６ -CONH-. * ６ R represents a bond to the main chain. ３２ R is a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxy hydrocarbon group having 1 to 20 carbon atoms. ３３ and R ３４ These are, independently of each other, a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted monovalent oxy hydrocarbon group having 1 to 20 carbon atoms, or R ３３ and R ３４ They are combined with each other R ３３ and R ３４ This represents an alicyclic hydrocarbon structure with 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded. ３６ (where g3 is an integer between 0 and 4.)

[0050] In the above formula (7-1), R ７２ From the viewpoint of copolymerizability of the monomer that gives structural unit (2A), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred. In the above formula (7-2), R７６ From the viewpoint of copolymerizability of the monomer that gives structural unit (2B), a hydrogen atom is preferred. Similarly, in the above formula (7-3), R ３１ The hydrogen atom or methyl group is preferred. In the above formula (7-2), L ６ or L in formula (7-3) ７ is a single bond, * ６ -COO- or * ６ -CONH- is preferred.

[0051] In the above equations (7-1) to (7-3), R ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R ３４ Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by [formula], include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0052] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, and t-butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups. Of these, R ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R ３４ The monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by is preferably an alkyl group, and more preferably an alkyl group having 1 to 4 carbon atoms.

[0053] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monovalent monocyclic alicyclic saturated hydrocarbon groups such as cyclopentyl group, cyclohexyl group, methylcyclopentyl group, ethylcyclopentyl group, methylcyclohexyl group, and ethylcyclohexyl group; monovalent monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl group, cyclohexenyl group, methylcyclopentenyl group, and methylcyclohexenyl group; monovalent polycyclic alicyclic saturated hydrocarbon groups such as norbornyl group, adamantyl group, and tricyclodecyl group; and monovalent polycyclic alicyclic unsaturated hydrocarbon groups such as norbornenyl group, tricyclodecenyl group, and indanyl group.

[0054] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, mesityl, naphthyl, methylnaphthyl, anthryl, methylanthryl, and indenyl groups; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

[0055] R ７３ or R ７４ Examples of monovalent unsaturated hydrocarbon groups represented by include the monocyclic or polycyclic alicyclic unsaturated hydrocarbon groups and aromatic hydrocarbon groups mentioned above. Examples of monovalent aromatic heterocyclic groups include the furyl group and the thienyl group.

[0056] R ７４ and R ７５ They are combined with each other R ７４ and R ７５ A cycloaliphatic hydrocarbon structure having 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded, and R ３３ and R ３４ They are combined with each other R ３３ and R ３４Examples of alicyclic hydrocarbon structures having 3 to 20 carbon atoms, formed together with the carbon atoms to which they are bonded, include monocyclic alicyclic saturated hydrocarbon structures such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; monocyclic alicyclic unsaturated hydrocarbon structures such as cyclopentene and cyclohexene; and polycyclic alicyclic hydrocarbon structures such as norbornane, adamantane, tricyclodecane, and tetracyclododecane.

[0057] R ７７ ~R ７９ or R ３２ ~R ３４ Examples of monovalent oxy hydrocarbon groups having 1 to 20 carbon atoms represented by the above R ７３ ~R ７５ , R ７７ ~R ７９ and R ３２ ~R ３４ Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include groups containing an oxygen atom at the end of the bonding side. ７７ ~R ７９ or R ３２ ~R ３４ Of these, the monovalent oxy hydrocarbon group represented is preferably an alkoxy group, a cycloalkoxy group, or a cycloalkylalkoxy group.

[0058] R ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R ３４ When the group represented by has substituents, examples of such substituents include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), hydroxyl groups, and alkoxy groups having 1 to 3 carbon atoms. Also, R ７４ and R ７５ They are combined with each other R ７４ and R ７５ When R forms an alicyclic hydrocarbon structure with 3 to 20 carbon atoms together with the bonded carbon atoms, or ３３ and R ３４ They are combined with each other R ３３ and R ３４When the atom to which it is bonded forms an alicyclic hydrocarbon structure having 3 to 20 carbon atoms, the substituents and alkyl groups exemplified above may be bonded to the ring.

[0059] L ５ The divalent chain-like organic group represented by is a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a linear or branched saturated hydrocarbon group in which the methylene group contains a heteroatom (for example, -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO-). ２ Examples include divalent groups with 2 to 20 carbon atoms that have been replaced with -). ５ Specific and preferred examples of the divalent alicyclic hydrocarbon group represented by R ７３ ~R ７５ , R ７７ ~R ７９ or R ３２ ~R ３４ Examples of monovalent alicyclic hydrocarbon groups represented by the above include groups similar to those exemplified above. ５ Preferably, it is a chain-like organic group.

[0060] R ３５ or R ３６ Examples of monovalent substituents represented by include C1-C3 alkyl groups, C1-C3 alkoxy groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, and the like. g2 and g3 are preferably 0-2, and more preferably 0 or 1.

[0061] Specific examples of structural units (2A) include structural units represented by the following formula. (In the formula, R ７２ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0062] Specific examples of structural units (2B) include structural units represented by the following formula. (In the formula, R ７６ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0063] Specific examples of structural units (2C) include structural units represented by the following formula. (In the formula, R ３１ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0064] Other structural units (II) include those derived from compounds in which the two carboxyl groups of an unsaturated dicarboxylic acid are protected (e.g., ditert-butyl maleate).

[0065] In polymer (P), the content of structural unit (II) is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to the total amount of structural units constituting polymer (P), from the viewpoint of further increasing the sensitivity of this composition. Furthermore, the content of structural unit (II) is preferably 85 mol% or less, more preferably 80 mol% or less, and even more preferably 75 mol% or less, relative to the total amount of structural units constituting polymer (P). By setting the content of structural unit (II) within the above range, the difference in dissolution rate in the developer between the exposed and unexposed areas can be increased while maintaining good sensitivity of this composition, and the pattern shape of the resist film can be improved.

[0066] • Structural Unit (III) Structural Unit (III) is a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (excluding structural units (I) and (II)). The polymer (P) is preferable in that it can further contain structural unit (III) in order to improve the resolution of the composition and to suppress the dissolution of unexposed areas into the developer, thereby sufficiently reducing development defects. In particular, polymers having a hydroxyl group bonded to an aromatic ring are preferably used in pattern formation using exposure with radiation of wavelength 50 nm or less, such as electron beams and EUV.

[0067] Examples of aromatic rings to which hydroxyl groups are bonded include aromatic hydrocarbon rings such as benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings. Of these, benzene rings or naphthalene rings are preferred, and benzene rings are more preferred. The number of hydroxyl groups bonded to the aromatic ring is not particularly limited. Preferably, there are 1 to 3 hydroxyl groups bonded to the aromatic ring, and more preferably, there are 1 or 2. Furthermore, the position of the hydroxyl group bonded to the aromatic ring is not particularly limited. For example, if structural unit (III) has a hydroxyl group bonded to a benzene ring, the bonded position of the hydroxyl group on the benzene ring in structural unit (III) may be ortho, meta, or para relative to other groups.

[0068] The aromatic ring to which the hydroxyl group is bonded may also have substituents other than the hydroxyl group bonded to it. Examples of such substituents include C1-C5 alkyl groups, C1-C5 alkoxy groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, and the like.

[0069] A concrete example of a structural unit (III) is the structural unit represented by the following formula (8). (In formula (8), R ５０ L is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. ２ These are single bonds, -O-, -COO-, or -CONH-. １０ R is a group obtained by removing (n1 + n2 + 1) hydrogen atoms from an aromatic ring. ４ R is a substituent different from a hydroxyl group and does not have an acid-dissociable group. n1 is an integer of 1 or more. n2 is an integer of 0 or more. If n2 is 2 or more, multiple R ４ They are either the same or different.

[0070] In the above formula (8), R ５０ From the viewpoint of copolymerization of the monomer that gives structural unit (III), a hydrogen atom or a methyl group is preferred. １０ The aromatic ring present is preferably an aromatic hydrocarbon ring, such as a benzene ring, naphthalene ring, anthracene ring, or phenanthrene ring. From the viewpoint of ease of synthesis and sensitivity of the monomer that gives structural unit (III), A１０ The aromatic ring present is preferably a benzene ring or a naphthalene ring, with a benzene ring being more preferable.

[0071] The position of the hydroxyl group bonded to the aromatic ring is not particularly limited. For example, if structural unit (III) has a hydroxyl group bonded to a benzene ring, the bonded position of the hydroxyl group on the benzene ring in structural unit (III) is different from that of other groups (L ２ ) may be in the ortho, meta, or para position.

[0072] R ４ Specific examples include monovalent hydrocarbon groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), carboxyl groups, ester groups, acyl groups, monovalent oxyhydrocarbon groups, etc. n1 is preferably 1 to 3, more preferably 1 or 2. n2 is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0073] Further specific examples of structural units (III) include structural units represented by the following formula. (In the formula, R ５０ (This is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.)

[0074] When the polymer (P) contains structural unit (III), the content of structural unit (III) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, relative to the total amount of structural units constituting the polymer (P). Furthermore, the content of structural unit (III) is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 45 mol% or less, relative to the total amount of structural units constituting the polymer (P). Setting the content of structural unit (III) within the above range is preferable because it can further improve the resolution of the composition.

[0075] • Structural Unit (IV) A structural unit (IV) is a structural unit having a lactone structure, a cyclic carbonate structure, or a sultone structure, or a ring structure combining two or more of these (excluding structural units (I) to (III)).

[0076] Specific examples of structural units (IV) include, for instance, the structural unit represented by the following formula. (In the formula, R Ｌ１ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0077] When the polymer (P) contains structural units (IV), the content of structural units (IV) is preferably 1 mol% or more, and more preferably 2 mol% or more, relative to the total amount of structural units in the polymer (P). Furthermore, the content of structural units (IV) in the polymer (P) is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, relative to the total amount of structural units in the polymer (P).

[0078] • Structural Unit (V) Structural unit (V) is a structural unit having an alcoholic hydroxyl group (excluding structural units (I) to (IV)). By introducing structural unit (V) into polymer (P), it is possible to further improve the effect of suppressing development defects when a resist pattern is formed with this composition. Hereinafter, "alcoholic hydroxyl group" refers to a group having a structure in which a hydroxyl group is directly bonded to a carbon atom constituting an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a chain hydrocarbon group, an alicyclic hydrocarbon group, may be substituted with a halogen group, etc., or may be an aliphatic hydrocarbon group constituting a heterocycle (such as a methylene group).

[0079] The structural unit (V) is preferably derived from an unsaturated monomer having an alcoholic hydroxyl group. The structure of the unsaturated monomer that gives structural unit (V) is not particularly limited as long as it has an alcoholic hydroxyl group. A specific example of structural unit (V) is the structural unit represented by the following formula. (In the formula, R Ａ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0080] When the polymer (P) contains structural units (V), from the viewpoint of fully obtaining the effect of suppressing development defects by introducing structural units (V), the content of structural units (V) is preferably 1 mol% or more relative to the total amount of structural units constituting the polymer (P). Furthermore, from the viewpoint of increasing the development contrast between the exposed and unexposed areas, the content of structural units (V) is preferably 20 mol% or less, and more preferably 10 mol% or less, relative to the total amount of structural units constituting the polymer (P).

[0081] In addition to the above, other structural units of the polymer (P) include, for example, structural units containing cyano groups, nitro groups, or sulfonamide groups (specifically, structural units derived from 2-cyanomethyladamantan-2-yl(meth)acrylate); and structural units containing non-acid-dissociable hydrocarbon groups (specifically, structural units derived from substituted or unsubstituted styrene (e.g., styrene units, bromostyrene units, etc.), structural units derived from vinylnaphthalene, structural units derived from n-pentyl(meth)acrylate, etc.). The content ratio of these structural units can be appropriately set according to each structural unit, as long as it does not impair the effects of this disclosure.

[0082] The weight-average molecular weight (Mw) of polymer (P) in terms of polystyrene, determined by gel permeation chromatography (GPC), is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and even more preferably 4,000 or more. Furthermore, the Mw of polymer (P) is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and even more preferably 15,000 or less. Setting the Mw of polymer (P) within the above range is advantageous because it improves the coating properties of the radiation-sensitive composition and sufficiently suppresses development defects.

[0083] The ratio of Mw to the number-average molecular weight (Mn) of the polymer (P) as determined by GPC (Mw / Mn, hereinafter also referred to as "dispersion") is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. In addition, Mw / Mn is usually 1.0 or more.

[0084] The polymer (P) preferably constitutes the base resin of the radiation-sensitive composition. The content of polymer (P) in the radiation-sensitive composition is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the total amount of solids contained in the radiation-sensitive composition. In this specification, "total amount of solids" refers to the sum of components other than the solvent.

[0085] The reason why a radiation-sensitive composition with excellent LWR performance and few development defects was obtained using polymer (P) containing structural unit (I) is not entirely clear, but the following is a possible explanation. Structural unit (I) is L １ (Single bond, * １ -CO-O-, * １ A is bonded to the main chain via -CO-NH- or -O-). １ (Aromatic ring group or aliphatic ring group) with "-L" ３ -R ３ -A ２ (X １ ) ｒ１ (R ４ ) ｒ２ A group containing an aryl structure represented by " and "-L ２ -R ２ -C(R ｆ１ ) (Caution ｆ２ ) - SO ３ － It has substructures to which groups having a sulfonic acid anionic structure represented by " are bonded. Polymers having such branched structures have a high glass transition temperature, which improves LWR performance but at the same time reduces solubility and can become a source of defects after development. In this respect, polymer (P) has A in the aryl structure ２ ni R ４ It is thought that the introduction of this material ensures solubility, and as a result, a radiation-sensitive composition with a well-balanced improvement in LWR performance and development defect suppression performance was obtained. However, this is merely speculation and does not limit the present invention in any way.

[0086] <Other Components> This composition may further contain components different from polymer (P) (hereinafter also referred to as "other components") along with polymer (P). Examples of other components include radiation-sensitive acid generators, solvents, and high-fluorine-content polymers.

[0087] (Radiation-sensitive acid generators) Radiation-sensitive acid generators are substances that generate acid upon irradiation with radiation. Radiation-sensitive acid generators may be ionic or nonionic. Ionic radiation-sensitive generators are preferred, and radiation-sensitive onium salts having a radiation-sensitive onium cation and an organic anion that is the conjugate base of the acid are preferably used. Organic anions are usually anions obtained by removing a proton from the acid group of an organic acid.

[0088] The radiation-sensitive acid generator may be a so-called radiation-sensitive acid generator or an acid diffusion control agent. Furthermore, this composition may contain both a radiation-sensitive acid generator and an acid diffusion control agent as the radiation-sensitive acid generator. Here, the radiation-sensitive acid generator is a substance that, upon exposure, generates a strong acid in the composition capable of detaching acid-dissociable groups from components in the radiation-sensitive composition. The acid diffusion control agent is a substance that suppresses the diffusion of acid derived from the radiation-sensitive acid generator generated by exposure within the resist film, thereby suppressing chemical reactions caused by acid in non-exposed areas. The radiation-sensitive acid generator is classified as either a radiation-sensitive acid generator or an acid diffusion control agent depending on the relative acid strength with respect to the components in the radiation-sensitive composition (specifically, monomers that provide structural units (I), or other radiation-sensitive acid generators when two or more radiation-sensitive acid generators are included). The degree of acidity can be evaluated by the acid dissociation constant (pKa). For example, the acid dissociation constant of the acid generated by the acid diffusion control agent is usually -3 or higher, preferably -1 ≤ pKa ≤ 7, and more preferably 0 ≤ pKa ≤ 5.

[0089] The radiation-sensitive acid generator is a component different from the polymer (P). The radiation-sensitive acid generator may be a so-called low-molecular-weight compound (also called a non-polymer) that does not have a molecular weight distribution, or it may be a polymer. If the radiation-sensitive acid generator is a polymer, the polymer does not contain structural unit (I). Low-molecular-weight compounds (non-polymers) can be preferably used as the radiation-sensitive acid generator because they allow for easy adjustment of the sensitivity of the radiation-sensitive composition and offer a high degree of freedom in selecting the radiation-sensitive acid generator. The molecular weight of the radiation-sensitive acid generator is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0090] • Radiation-sensitive acid generator The type of radiation-sensitive acid generator to be incorporated into this composition is not particularly limited, and known radiation-sensitive acid generators used in resist pattern formation can be used as appropriate. The radiation-sensitive acid generator is preferably a compound that, under normal conditions, generates an acid (preferably a strong acid such as sulfonic acid, sulfonimide, or sulfonemethide) in the composition that is more acidic than the acid generated by the acid diffusion control agent (more specifically, a photodecayable base), thereby inducing the dissociation of an acid-dissociable group. Here, "normal conditions" refers to the conditions under which post-exposure baking (PEB) is performed at 110°C for 60 seconds.

[0091] When using an onium salt as a radiation-sensitive acid generator, from the viewpoint of increasing the sensitivity of the radiation-sensitive composition and forming a resist film with superior lithography performance, the radiation-sensitive acid generator preferably has a sulfonium cation or an iodonium cation, and more preferably has an arylsulfonium cation or an aryliodonium cation. A specific example of a cation constituting the radiation-sensitive acid generator is M in formula (1) above. ＋ Examples similar to the anions exemplified above can be cited.

[0092] The organic anions present in the radiation-sensitive acid generator are not particularly limited. Sulfonate anions, sulfonimide anions, or sulfonmethide anions are preferred because they can increase the sensitivity of the radiation-sensitive composition. Specific examples of sulfonate anions include those represented by the following formula.

[0093] When a radiation-sensitive acid generator is incorporated into this composition, the content of the radiation-sensitive acid generator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, per 100 parts by mass of polymer (P), from the viewpoint of sufficiently obtaining the effect of improving sensitivity due to the incorporation of the radiation-sensitive acid generator. Furthermore, from the viewpoint of suppressing the occurrence of development defects caused by the radiation-sensitive acid generator, the content of the radiation-sensitive acid generator is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of polymer (P).

[0094] From the viewpoint of improving the lithographic properties of the acid diffusion control agent radiation-sensitive composition, it is preferable that the radiation-sensitive composition contains a radiation-sensitive onium salt (hereinafter also referred to as a "photodecayable base") having a radiation-sensitive onium cation and an organic anion that is a conjugate base of the acid as an acid diffusion control agent. The photodecayable base is preferably a substance that generates an acid with low acidity upon exposure rather than a monomer that gives structural unit (I), and an onium salt that generates a carboxylic acid, sulfonic acid, or sulfonamide upon exposure is more preferable. Furthermore, in terms of forming a resist film with higher lithographic performance, it is preferable to use a radiation-sensitive onium salt having a sulfonium cation or an iodonium cation as the photodecayable base.

[0095] A specific example of a radiation-sensitive onium cation in a photodecayable base is M in formula (1) above. ＋ Examples similar to the anions exemplified above can be cited.

[0096] Examples of organic anions found in photodecayable bases include the anion represented by the following formula.

[0097] When an acid diffusion control agent is incorporated into a radiation-sensitive composition, the content of the acid diffusion control agent is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, per 100 parts by mass of polymer (P), from the viewpoint of sufficiently obtaining the effect of improving sensitivity and reducing LWR. Furthermore, from the viewpoint of suppressing the occurrence of development defects caused by the acid diffusion control agent, the content of the acid diffusion control agent is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of polymer (P).

[0098] When an acid diffusion control agent is incorporated into a radiation-sensitive composition, the content of the acid diffusion control agent in the radiation-sensitive composition is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total amount of the radiation-sensitive acid generator and the monomer that provides structural units (I) in the polymer (P) contained in the composition. Furthermore, the content of the acid diffusion control agent is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less, relative to the total amount of the radiation-sensitive acid generator and the monomer that provides structural units (I) contained in the composition. By setting the content of the acid diffusion control agent within the above range, the LWR performance of the radiation-sensitive composition can be further improved.

[0099] (Solvent) The solvent is preferably a solvent capable of dissolving or dispersing the components incorporated into the radiation-sensitive composition, and organic solvents can be preferably used. Specific examples of solvents include alcohols, ethers, ketones, amides, esters, hydrocarbons, and the like.

[0100] Examples of alcohols include aliphatic monoalcohols with 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohols with 3 to 18 carbon atoms such as cyclohexanol; polyhydric alcohols with 2 to 18 carbon atoms such as 1,2-propylene glycol; and polyhydric alcohol partial ethers with 3 to 19 carbon atoms such as propylene glycol monomethyl ether. Examples of ethers include dialkyl ethers such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ethers such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ethers such as diphenyl ether and anisole.

[0101] Examples of ketones include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, trimethylnonanone, and other linear ketones; cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, and other cyclic ketones; and 2,4-pentanedione, acetonylacetone, acetophenone, and diacetone alcohol. Examples of amides include cyclic amides such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and linear amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0102] Examples of esters include monocarboxylic acid esters such as n-butyl acetate, ethyl lactate, and methyl 2-hydroxyisobutyrate; polyhydric alcohol carboxylates such as propylene glycol diacetate; polyhydric alcohol partial ether carboxylates such as propylene glycol monomethyl ether acetate; polyhydric carboxylic acid diesters such as diethyl oxalate; carbonates such as dimethyl carbonate and diethyl carbonate; and cyclic esters such as γ-butyrolactone. Examples of hydrocarbons include aliphatic hydrocarbons with 5 to 12 carbon atoms such as n-pentane and n-hexane; and aromatic hydrocarbons with 6 to 16 carbon atoms such as toluene and xylene.

[0103] The solvent preferably contains at least one selected from the group consisting of esters and ketones, and more preferably contains at least one selected from the group consisting of polyhydric alcohol partial ether carboxylates and cyclic ketones.

[0104] (High Fluorine Content Polymers) High fluorine content polymers (hereinafter also referred to as "polymer (F)") are polymers with a higher mass content of fluorine atoms than polymer (P). Polymer (F) is incorporated into radiation-sensitive compositions, for example, as a surface modifier to adjust the hydrophilicity and hydrophobicity of the surface of a resist film, or as a modifier to further enhance lithography performance.

[0105] The fluorine atom content of polymer (F) is not particularly limited, as long as it is greater than that of polymer (P). The fluorine atom content of polymer (F) is preferably 1% by mass or more, more preferably 4% by mass or more, and even more preferably 7% by mass or more. Furthermore, the fluorine atom content of polymer (F) is preferably 60% by mass or less, and more preferably 40% by mass or less. Note that the fluorine atom content (by mass%) of polymer is: １３ The polymer structure can be determined by measuring C-NMR spectra, and the formula can be calculated from that structure.

[0106] When the radiation-sensitive composition contains polymer (F), the content of polymer (F) in the radiation-sensitive composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of polymer (P). Furthermore, the content of polymer (F) is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of polymer (P).

[0107] (Other Optional Components) The radiation-sensitive composition may further contain components other than the polymer (P), radiation-sensitive acid generator, solvent, and polymer (F) described above (hereinafter also referred to as "other optional components"). Examples of other optional components include aromatic carboxylic acids (e.g., benzoic acid, salicylic acid, benzenedicarboxylic acid, etc.), aliphatic carboxylic acids (e.g., acetic acid, oxalic acid, pyruvic acid, 1-adamantanecarboxylic acid, etc.), surfactants, alicyclic skeleton-containing compounds (e.g., 2-adamantanone, t-butyl deoxycholate, etc.), sensitizers, and segregation promoters. The content of the other optional components can be appropriately set according to each compound, within a range that does not impair the effects of the present invention.

[0108] <Method for Producing Radiation-Sensitive Composition> A radiation-sensitive composition can be produced, for example, by mixing a polymer (P) and other components as needed in desired proportions, and filtering the resulting mixture, preferably using a filter (for example, a filter with a pore size of about 0.2 μm). The solid content concentration of the radiation-sensitive composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. Furthermore, the solid content concentration of the radiation-sensitive composition is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less. Setting the solid content concentration of the radiation-sensitive composition within the above range is advantageous in that it allows for good coatability and good shape of the resist pattern.

[0109] The resulting radiation-sensitive composition can be used as a positive-type pattern-forming composition for forming patterns using an alkaline developer, or as a negative-type pattern-forming composition for using a developer containing an organic solvent.

[0110] <<Polymers and Compounds>> The present disclosure provides a polymer (P) comprising the structural unit represented by the above formula (1). Polymer (P) is suitable as a polymer component of a radiation-sensitive composition used for resist pattern formation.

[0111] Furthermore, the present disclosure provides a compound represented by the following formula (2). The compound represented by the following formula (2) is suitable as a monomer constituting a polymer component of a radiation-sensitive composition used for resist pattern formation. (In formula (2), R １ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, * １ -CO-O-, * １ It is -CO-NH- or -O-. １ " is R １ This represents the bond with the carbon atom to which it is bonded. A １ L is an aromatic ring group or aliphatic ring group with (r3+3) valency. ２ and L ３ These are, independently of each other, single or divalent linking groups. ２ R is a single bond, an alkanediyl group, or a fluoroalkanediyl group. ｆ１ and R ｆ２ These are, independently of each other, a hydrogen atom, a cyano group, a nitro group, a fluorine atom, or a fluoroalkyl group. ３ A is a single bond or a substituted or unsubstituted alkanediyl group. ２ is an aromatic ring group with (r1 + r2 + 1) valency. １ R is a halogen atom or an alkyl halogen. ４ R is a monovalent substituent excluding halogen atoms and alkyl halides. ５ X is a monovalent substituent. r2 is an integer greater than or equal to 1. r1 and r3 are independent integers greater than or equal to 0. If r1 is 2 or greater, multiple X １ They are the same or different. If r2 is 2 or more, there are multiple R ４ They are the same or different. If r3 is 2 or more, there are multiple R ５ They are the same or different. M ＋(It is a radiation-sensitive cation.)

[0112] The compound represented by formula (2) above corresponds to the monomer that gives the structural unit (I) described above. The explanation of each symbol in formula (2) above is the same as the explanation for formula (1) above.

[0113] Specific examples of compounds represented by formula (2) above include compounds represented by the following formula. However, compounds represented by formula (2) above are not limited to those with the following structure. In the following formula, R １ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, M ＋ It is a radiation-sensitive cation.

[0114] The method for synthesizing the compound represented by formula (2) above is not particularly limited and can be produced by appropriately combining standard organic chemistry methods. A preferred example of a method for synthesizing the compound represented by formula (2) above is to use the compound represented by formula (R-1) below, the onium salt represented by formula (R-2) below (e.g., an ammonium salt), and the compound represented by formula (R-3) below as raw materials, react them in a suitable solvent, and optionally in the presence of a catalyst, to obtain an intermediate product, and then react the obtained intermediate product with a salt that gives the cation moiety in formula (2) above (e.g., a sulfonium halide or iodonium halide) to obtain the compound represented by formula (2). However, the method for synthesizing the compound represented by formula (2) above is not limited to the above. (In formulas (R-1) to (R-3), Ar １ This is an aromatic ring. １ , L １ , R ５ , R ２ , R ｆ１ , R ｆ２ , R ３ A ２ , X １ , R ４ r1, r2, and r3 are equivalent to those in equation (2) above. Z １ and Z ２ Of these, one is a functional group that can react with a hydroxyl group, and the other is a functional group that can react with a carboxyl group.＋ (It is a cation.)

[0115] From the viewpoint of raw material availability, compounds having a salicylic acid structure (e.g., vinyl salicylic acid) can be preferably used as the compound represented by the above formula (R-1). In the above formulas (R-2) and (R-3), examples of functional groups that can react with a hydroxyl group include an amino group, a carboxyl group, and -COX (where X is a halogen atom). Examples of functional groups that can react with a carboxyl group include a hydroxyl group, an amino group, and an epoxy group. L ＋ Preferably, it is an ammonium cation.

[0116] ≪Method for Forming a Resist Pattern≫ The resist pattern formation method in this disclosure includes a step of coating a radiation-sensitive composition onto one side of a substrate (hereinafter also referred to as the "coating step"), a step of exposing the resist film obtained in the coating step (hereinafter also referred to as the "exposure step"), and a step of developing the resist film exposed in the exposure step (hereinafter also referred to as the "development step"). Examples of patterns formed by the resist pattern formation method of this disclosure include line-and-space patterns and hole patterns. Since the resist pattern formation method of this disclosure forms a resist film using the radiation-sensitive composition of this disclosure described above, it is possible to form a resist pattern with good sensitivity and LWR performance. Each step will be described below.

[0117] [Coating Process] In the coating process, a resist film is formed on the substrate by coating one side of the substrate with a radiation-sensitive composition. Conventional known substrates can be used as substrates for forming the resist film, such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 59-93448, may be formed on the substrate and used. Examples of coating methods for the radiation-sensitive composition include rotary coating (spin coating), casting coating, and roll coating. After coating, a soft bake (hereinafter also referred to as "SB") may be performed to volatilize the solvent in the coating film. The temperature of the SB is preferably 60°C or higher, more preferably 80°C or higher. The temperature of the SB is preferably 140°C or lower, more preferably 120°C or lower. The duration of the SB is preferably 5 seconds or more, more preferably 10 seconds or more. The duration of the SB is preferably 600 seconds or less, more preferably 300 seconds or less. The average thickness of the formed resist film is preferably 10 to 1,000 nm, and more preferably 20 to 500 nm. Soft baking is also referred to as pre-baking.

[0118] [Exposure Process] In the exposure process, the resist film obtained by the coating process described above is exposed. This exposure is performed by irradiating the resist film with radiation through a photomask, and possibly through an immersion medium such as water. Examples of radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and gamma rays, depending on the line width of the desired pattern; electron beams, alpha rays, and other charged particle beams. Of these, the radiation irradiated onto the resist film formed using this composition is preferably far ultraviolet light, EUV, or an electron beam; more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, or an electron beam; even more preferably ArF excimer laser light, EUV, or an electron beam; even more preferably EUV or an electron beam; and particularly preferably EUV.

[0119] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in the exposed portion of the resist film by acid generated from a compound that generates acid upon exposure (such as a radiation-sensitive acid generator). This PEB can increase the difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is preferably 50°C or higher, more preferably 80°C or higher. Furthermore, the PEB temperature is preferably 180°C or lower, more preferably 130°C or lower. The PEB duration is preferably 5 seconds or more, more preferably 10 seconds or more. Furthermore, the PEB duration is preferably 600 seconds or less, more preferably 300 seconds or less.

[0120] [Development Process] In the development process, the exposed resist film is developed. This allows for the formation of the desired resist pattern. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry the film. The development method in the development process may be alkaline development or organic solvent development.

[0121] In the case of alkaline development, examples of developer solutions include alkaline aqueous solutions containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred. In the case of organic solvent development, examples of developer solutions include one or more organic solvents such as hydrocarbons, ethers, esters, ketones, and alcohols, and solvents containing the above organic solvents.

[0122] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by puddling the developer solution onto the substrate surface using surface tension and leaving it still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method).

[0123] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0124] The method for measuring the molecular weight of polymers is described below. [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of polymers were measured by gel permeation chromatography (GPC) using GPC columns manufactured by Tosoh Corporation (two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column) under the following conditions: Eluent: Tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40°C Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0125] <Synthesis of Monomer (A)> [Synthesis Example A-1: ​​Synthesis of Monomer (A-1)] Monomer (A-1) was synthesized according to the reaction scheme below.

[0126] 5-vinyl salicylic acid (40 mmol), CDI (carbonyl diimidazole) (48 mmol), and dichloromethane (100 mL) were added to the reaction vessel and stirred at room temperature for 1 hour. Compound (A-1-a) (48 mmol) and diazabicycloundecene (48 mmol) were added and stirred at room temperature for 3 hours. Hydrochloric acid was added while cooling to 0°C to separate the organic layer. The organic layer was washed with aqueous sodium bicarbonate solution and then with ultrapure water. The solvent was removed by distillation to obtain compound (A-1-b) in good yield.

[0127] Compound (A-1-b) (32 mmol) and acetonitrile (250 mL) were added to a reaction vessel placed in an ice bath and stirred. 3,5-diiodo-2-methoxybenzoyl chloride (35 mmol) was added, and triethylamine (35 mmol) dissolved in acetonitrile (30 mL) was added dropwise, and the mixture was stirred at room temperature for 3 hours. The solvent was removed, and the organic layer was separated by adding dichloromethane and hydrochloric acid. The organic layer was washed with aqueous sodium bicarbonate solution, and then with ultrapure water. The solvent was removed by distillation, and compound (A-1-c) was obtained in good yield by purification by silica gel column chromatography.

[0128] Compound (A-1-c) (25 mmol), compound (A-1-d) (25 mmol), dichloromethane (50 mL), and ultrapure water (50 mL) were added to a reaction vessel and stirred at room temperature for 2 hours. The mixture was diluted with dichloromethane and washed with ultrapure water. The organic layer was dried over sodium sulfate and filtered. The solvent was removed by distillation, and monomer (A-1) was obtained in good yield by purification by silica gel column chromatography.

[0129] [Synthesis Examples A-2 to A-6, A-17 to A-22: Synthesis of monomers (A-2) to (A-6), (A-17) to (A-22)] Monomers (A-2) to (A-6) and (A-17) to (A-22), represented by the following formulas, were synthesized in the same manner as in Synthesis Example A-1, except that the substrate and reagent used were appropriately selected.

[0130] [Synthesis Example A-7: Synthesis of Monomer (A-7)] Monomer (A-7) was synthesized according to the reaction scheme below.

[0131] Compound (A-7-a) (32 mmol), potassium carbonate (38 mmol), and acetonitrile (250 mL) were added to a reaction vessel placed in an ice bath and stirred. Compound (A-7-b) (38 mmol) was added and stirred at room temperature for 3 hours. The precipitated solid was filtered, and hydrochloric acid was added to separate the organic layer. The organic layer was washed with an aqueous sodium bicarbonate solution, and then with ultrapure water. The organic layer was dried over sodium sulfate and filtered. The solvent was removed by distillation, and compound (A-7-c) was obtained in good yield by purification by silica gel column chromatography.

[0132] Compound (A-7-c) (25 mmol), compound (A-7-d) (25 mmol), dichloromethane (50 mL), and ultrapure water (50 mL) were added to a reaction vessel and stirred at room temperature for 2 hours. The mixture was diluted with dichloromethane and washed with ultrapure water. The organic layer was dried over sodium sulfate and filtered. The solvent was removed by distillation, and monomer (A-7) was obtained in good yield by silica gel column chromatography.

[0133] [Synthesis Examples A-8 to A-10: Synthesis of Monomers (A-8) to (A-10)] Monomers (A-8) to (A-10), represented by the following formulas, were synthesized in the same manner as in Synthesis Example A-7, except that the substrate and reagent used were appropriately selected.

[0134] [Synthesis Example A-11: Synthesis of Monomer (A-11)] Monomer (A-11) was synthesized according to the reaction scheme below.

[0135] 1,4-dihydroxy-2-naphthoic acid (40 mmol), CDI (48 mmol), and dichloromethane (100 mL) were added to the reaction vessel and stirred at room temperature for 1 hour. Compound (A-11-a) (48 mmol) and diazabicycloundecene (48 mmol) were added and stirred at room temperature for 3 hours. Hydrochloric acid was added while cooling to 0°C to separate the organic layer. The organic layer was washed with aqueous sodium bicarbonate solution and then with ultrapure water. The solvent was removed by distillation to obtain compound (A-11-b) in good yield.

[0136] Compound (A-11-b) (32 mmol), pyridine (38 mmol), DMAP (4-dimethylaminopyridine) (3.2 mmol), and dichloromethane (100 mL) were added to a reaction vessel placed in an ice bath and stirred. Methacrylic anhydride (38 mmol) was added dropwise, and the mixture was stirred at room temperature for 3 hours. The organic layer was separated by adding aqueous ammonium chloride. The organic layer was washed with aqueous ammonium chloride and then with ultrapure water. The organic layer was dried over sodium sulfate and filtered. The solvent was removed by distillation, and compound (A-11-c) was obtained in good yield by purification by silica gel column chromatography.

[0137] Compound (A-11-c) (20 mmol), compound (A-11-d) (24 mmol), EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide) (24 mmol), DMAP (2 mmol), and dichloromethane (50 mL) were added to a reaction vessel and stirred at room temperature for 2 hours. Hydrochloric acid was added to separate the organic layer. The organic layer was washed with aqueous sodium bicarbonate solution, and then with ultrapure water. The organic layer was dried over sodium sulfate and filtered. The solvent was removed by distillation, and monomer (A-11) was obtained in good yield by purification by silica gel column chromatography.

[0138] [Synthesis Examples A-12 to A-14: Synthesis of Monomers (A-12) to (A-14)] Monomers (A-12) to (A-14), represented by the following formulas, were synthesized in the same manner as in Synthesis Example A-11, except that the substrate and reagent used were appropriately selected.

[0139] [Synthesis Example A-15: Synthesis of Monomer (A-15)] Monomer (A-15) was synthesized according to the reaction scheme below.

[0140] 3-acetyl-4-hydroxybenzoic acid (40 mmol), CDI (48 mmol), and dichloromethane (100 mL) were added to the reaction vessel and stirred at room temperature for 1 hour. Compound (A-15-a) (48 mmol) and diazabicycloundecene (48 mmol) were added and stirred at room temperature for 3 hours. Hydrochloric acid was added while cooling to 0°C to separate the organic layer. The organic layer was washed with aqueous sodium bicarbonate solution and ultrapure water. The solvent was removed by distillation to obtain compound (A-15-b) in good yield.

[0141] Compound (A-15-b) (30 mmol), methacrylic acid (39 mmol), EDC (39 mmol), DMAP (6 mmol), and dichloromethane (40 mL) were added to a reaction vessel and stirred at room temperature for 2 hours. Hydrochloric acid was added while cooling to 0°C to separate the organic layer. The organic layer was washed with aqueous sodium bicarbonate solution, and then with ultrapure water. The solvent was removed by distillation to obtain compound (A-15-c) in good yield.

[0142] Compound (A-15-c) (21 mmol), compound (A-15-d) (20 mmol), pTsOH (p-toluenesulfonic acid) (4 mmol), and toluene (100 mL) were added to a reaction vessel, and the mixture was heated under reflux for 5 hours in a Dean-Stark apparatus. The organic layer was separated by adding an aqueous sodium bicarbonate solution. The organic layer was dried over sodium sulfate and filtered. The solvent was removed by distillation, and monomer (A-15) was obtained in good yield by purification by silica gel column chromatography.

[0143] [Synthesis Example A-16: Synthesis of Monomer (A-16)] Monomer (A-16), represented by the following formula, was synthesized in the same manner as in Synthesis Example A-15, except that the substrate and reagent used were appropriately selected.

[0144] [Synthesis Examples CA-1 to CA-4: Synthesis of Monomers (CA-1) to (CA-4)] Monomers (CA-1) to (CA-4), represented by the following formulas, were synthesized by appropriately selecting precursors using known methods.

[0145] The structural formulas of monomers (A-1) to (A-22) and (CA-1) to (CA-4) are shown below.

[0146] <Synthesis of Polymers> Polymers (P-1) to (P-37) and polymers (CP-1) to (CP-4) were synthesized according to the following method. Monomers (A-1) to (A-22), monomers (CA-1) to (CA-4), and monomers (M-1) to (M-15) shown below were used for the synthesis of polymers. In the following synthesis examples, unless otherwise specified, "parts by mass" means the value when the total mass of the monomers used is 100 parts by mass, and "mol%" means the value when the total number of moles of the monomers used is 100 mol%.

[0147] [Synthesis Example P-1: Synthesis of Polymer (P-1)] Monomer (A-1), monomer (M-5), and monomer (M-1) were dissolved in 1-methoxy-2-propanol (200 parts by mass) so that the molar ratio in the final polymer was 15 / 55 / 30. As an initiator, 6 mol% of azobisisobutyronitrile (AIBN) was added relative to the total amount of monomers to prepare a monomer solution. Meanwhile, 100 parts by mass of 1-methoxy-2-propanol was placed in an empty reaction vessel and heated to 80°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours. After that, it was heated at 80°C for another 3 hours. After the polymerization reaction was complete, the polymerization solution was cooled to room temperature. The cooled polymerization solution was added to 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 100 parts by mass of hexane in the polymerization solution, and then dried at 50°C for 12 hours to obtain a white powdery polymer (P-1). The composition of the obtained polymer was １ The Mw and dispersion (Mw / Mn) were confirmed by 1H-NMR under the GPC conditions described above. The Mw and Mw / Mn of the polymer are shown in Table 1.

[0148] [Synthesis Examples P-2 to P-37 and Comparative Synthesis Examples CP-1 to CP-4: Synthesis of Polymers (P-2) to (P-37) and Polymers (CP-1) to (CP-4)] Polymers (P-2) to (P-37) and polymers (CP-1) to (CP-4) were obtained by the same procedure as in Synthesis Example P-1, except that the monomers of the types listed in Table 1 were blended so that the molar ratio in the final polymer was as shown in Table 1. In Comparative Synthesis Examples CP-1 to CP-4, monomers (CA-1) to (CA-4) were used instead of the monomers that give structural unit (I). The Mw and Mw / Mn of each obtained polymer are shown in Table 1.

[0149]

[0150] <Preparation of Radiation-Sensitive Compositions> The polymers, radiation-sensitive acid generators, acid diffusion control agents, and solvents used in the preparation of the radiation-sensitive compositions in the following examples and comparative examples are shown below. In the following examples and comparative examples, "parts by mass" refers to the value when the mass of the polymer used is 100 parts by mass. "Mole%" refers to the value when the total number of moles of the radiation-sensitive acid generator used and the anions in the monomers used in the synthesis of the polymer is 100 mol%.

[0151] [Polymers] Polymers (P-1) to (P-37) synthesized in the above synthesis examples P-1 to P-37 and polymers (CP-1) to (CP-4) synthesized in comparative synthesis examples CP-1 to CP-4 were used.

[0152] [Radiation-sensitive acid generator] Compounds represented by the following formulas (B-1) to (B-7) were used.

[0153] [Acid diffusion control agent] Compounds represented by the following formulas (Q-1) to (Q-6) were used.

[0154] [Solvents] The following solvents were used: E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: Methyl 2-hydroxyisobutyrate E-4: Diacetone alcohol

[0155] [Example 1: Preparation of radiation-sensitive composition (R-1)] 100 parts by mass of (P-1), 7.5 parts by mass of (B-1), and (Q-1) were mixed at 30 mol% relative to the total of the anions in the monomer used in the synthesis of (P-1) and (B-1), along with 5,000 parts by mass of (E-1) and 1,500 parts by mass of (E-2). The resulting mixture was filtered through a filter with a pore size of 0.2 μm to prepare the radiation-sensitive composition (R-1).

[0156] [Examples 2-52 and Comparative Examples 1-4: Preparation of Radiation-Sensitive Compositions (R-2)-(R-52) and Radiation-Sensitive Compositions (CR-1)-(CR-4)] Radiation-sensitive compositions (R-2)-(R-52) and (CR-1)-(CR-4) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 2 and 3 below were used.

[0157]

[0158]

[0159] <Formation of Resist Pattern> The radiation-sensitive composition prepared above was applied to the surface of a 12-inch silicon wafer on which a 40 nm thick underlayer film (AL412 (manufactured by Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron). After spin coating 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 light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination conditions: Conventional s = 0.89, mask imecDEFECT32FFR02). The resist film was subjected to photobleaching at 110°C for 60 seconds. Next, the image was developed using a 2.38 wt% TMAH aqueous solution at 23°C for 30 seconds to form a positive-type 32 nm line-and-space pattern.

[0160] <Evaluation> The LWR and number of development defects of each radiation-sensitive composition were evaluated for each resist pattern formed as described above by measuring according to the method below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the length of the resist patterns. The evaluation results are shown in Table 4 below.

[0161] [LWR] The EUV resist pattern was observed from above using the scanning electron microscope described above. The line width was measured at 50 arbitrary points, and the 3-sigma value was determined from the distribution of these measurements, which was defined as the LWR (unit: nm). A smaller LWR value indicates less line jaggedness and better quality. An LWR value of less than 3.3 nm was classified as "A" (excellent), 3.3 nm or more and less than 3.6 nm as "B" (good), 3.6 nm or more and less than 3.9 nm as "C" (slightly poor), and 3.9 nm or more as "D" (poor).

[0162] [Development Defect Count] A resist film was exposed and developed at the optimal exposure level to form a 32 nm line-and-space pattern. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). The measured defects were then classified into those determined to be originating from the resist film and those originating from the external environment. The development defect count was judged as follows: less than 40 defects determined to be originating from the resist film were classified as "A" (excellent), 40 or more but less than 50 as "B" (good), 50 or more but less than 60 as "C" (slightly poor), and 60 or more as "D" (poor).

[0163]

[0164] As is clear from the results in Table 4, all of the radiation-sensitive compositions of Examples 1 to 52 showed a good balance of improvement in LWR and development defect count. In contrast, the radiation-sensitive compositions of Comparative Examples 1 to 4, which were prepared using polymers (CP-1) to (CP-4) that do not contain the structural unit represented by formula (1) above, instead of polymer (P), were inferior to those of Examples 1 to 52.

[0165] More specifically, in Comparative Examples 1 and 2, the radiation-sensitive compositions synthesized using monomers in formula (1) where r2 is 0 resulted in a high number of development defects, and both Comparative Examples 1 and 2 received a "D" rating for the number of development defects. １ In Comparative Example 4, a radiation-sensitive composition synthesized using monomers that do not have a branched structure branching from the above formula (1), the line jitter was large, and the LWR was rated as "D". Similar to Comparative Example 4, A in formula (1) above １ In Comparative Example 3, a radiation-sensitive composition synthesized using monomers that do not have a branched structure branching from a single molecule, there were no "D" ratings, but the LWR was rated "C" and the number of development defects was rated "B," making it inferior overall to Examples 1 to 52.

[0166] Based on the above results, it can be said that the radiation-sensitive composition and resist pattern formation method of this disclosure can form patterns with low LWR and reduced development defects. Therefore, the radiation-sensitive composition and resist pattern formation method of this disclosure are suitable for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A radiation-sensitive composition comprising a polymer containing a structural unit represented by the following formula (1). (In formula (1), R １ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L １ is a single bond, * １ -CO-O-, * １ -CO-NH- or -O-. * １ represents a bonding hand to the carbon atom to which R １ is bonded. A １ is a (r3+3)-valent aromatic cyclic group or aliphatic cyclic group. L ２ and L ３ are each independently a single bond or a divalent linking group. R ２ is a single bond, an alkanediyl group or a fluoroalkanediyl group. R ｆ１ and R ｆ２ are each independently a hydrogen atom, a cyano group, a nitro group, a fluorine atom or a fluoroalkyl group. R ３ is a single bond or a substituted or unsubstituted alkanediyl group. A ２ is a (r1+r2+1)-valent aromatic cyclic group. X １ is a halogen atom or a halogenated alkyl group. R ４ is a monovalent substituent excluding a halogen atom and a halogenated alkyl group. R ５ is a monovalent substituent. r2 is an integer of 1 or greater. r1 and r3 are each independently an integer of 0 or greater. When r1 is 2 or greater, a plurality of X １ are the same or different. When r2 is 2 or greater, a plurality of R ４ are the same or different. When r3 is 2 or greater, a plurality of R ５ are the same or different. M ＋ is a radiation-sensitive cation.) 2. R in formula (1) above ４ However, independently of each other, C1-C6 alkyl groups, C1-C6 alkoxy groups, C1-C6 halogenated alkoxy groups, hydroxyl groups, carboxyl groups, *-CO-R, *-S (=O) ２ -R, *-NH-S (=O) ２ -R, *-S (=O) ２ The radiation-sensitive composition according to claim 1, wherein the group is -NH-R, *-NH-CO-R, *-CO-O-R, *-CO-NH-R, a cyano group or a nitro group (wherein R is an alkyl group having 1 to 5 carbon atoms, and * represents a bond).

3. The radiation-sensitive composition according to claim 1, wherein the polymer further comprises a structural unit having an acid-dissociable group.

4. The radiation-sensitive composition according to claim 1, wherein the polymer further comprises a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring.

5. The radiation-sensitive composition according to claim 1, further comprising an acid diffusion control agent.

6. L in formula (1) above ２ and L ３ However, they are independent of each other, * ２ -CO-O-, * ２ -O-CO- or -O-(* ２ is, A １ The radiation-sensitive composition according to claim 1, which represents a bonding bond with ().

7. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using a radiation-sensitive composition according to any one of claims 1 to 6; exposing the resist film; and developing the exposed resist film.

8. A polymer containing a structural unit represented by the following formula (1). (In formula (1), R １ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a single bond, * １ -CO-O-, * １ It is -CO-NH- or -O-. １ R １ This represents the bond with the carbon atom to which it is bonded. A １ L is an aromatic ring group or aliphatic ring group with (r3+3) valency. ２ and L ３ These are, independently of each other, single or divalent linking groups. ２ R is a single bond, an alkanediyl group, or a fluoroalkanediyl group. ｆ１ and R ｆ２ These are, independently of each other, a hydrogen atom, a cyano group, a nitro group, a fluorine atom, or a fluoroalkyl group. ３ A is a single bond or a substituted or unsubstituted alkanediyl group. ２ is an aromatic ring group with (r1 + r2 + 1) valency. １ R is a halogen atom or an alkyl halogen. ４ R is a monovalent substituent excluding halogen atoms and alkyl halides. ５ X is a monovalent substituent. r2 is an integer greater than or equal to 1. r1 and r3 are independent integers greater than or equal to 0. If r1 is 2 or greater, multiple X １ They are the same or different. If r2 is 2 or more, there are multiple R ４ They are the same or different. If r3 is 2 or more, there are multiple R ５ They are the same or different. M ＋ (It is a radiation-sensitive cation.) 9. A compound represented by the following formula (2). (In formula (2), R １ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L １ is a single bond, * １ -CO-O-, * １ -CO-NH- or -O-. "* １ " represents a bond to the carbon atom to which R １ binds. A １ is an (r3+3)-valent aromatic ring group or aliphatic cyclic group. L ２ and L ３ are each independently a single bond or a divalent linking group. R ２ is a single bond, an alkanediyl group or a fluoroalkanediyl group. R ｆ１ and R ｆ２ are each independently a hydrogen atom, a cyano group, a nitro group, a fluorine atom or a fluoroalkyl group. R ３ is a single bond or a substituted or unsubstituted alkanediyl group. A ２ is an (r1+r2+1)-valent aromatic ring group. X １ is a halogen atom or a halogenated alkyl group. R ４ is a monovalent substituent excluding a halogen atom and a halogenated alkyl group. R ５ is a monovalent substituent. r2 is an integer of 1 or more. r1 and r3 are each independently an integer of 0 or more. When r1 is 2 or more, a plurality of X １ are the same or different. When r2 is 2 or more, a plurality of R ４ are the same or different. If r3 is 2 or more, multiple R ５ They are the same or different. M ＋ (It is a radiation-sensitive cation.)

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