Radiation-sensitive composition, resist pattern forming method, radiation-sensitive acid generator, and compound

Abstract

Provided is a radiation-sensitive composition which comprises a polymer (P) including a structural unit having an acid-dissociable group, and which satisfies at least one of a first requirement and a second requirement. First requirement: The radiation-sensitive composition further contains a compound represented by formula (1). Second requirement: The polymer (P) further includes a structural unit derived from an onium salt compound represented by formula (1). In formula (1), RA represents a halogen atom, -NO2, -OH, -SH, -COOH, or a group represented by formula (i). RB represents -CN, a hydrogen atom, a halogen atom, -NO2, -OH, -SH, -COOH, or a group represented by formula (i). Z+ represents a radiation-sensitive onium cation.

Description

Radiation-sensitive compositions, methods for forming resist patterns, radiation-sensitive acid generators and compounds

[0001] [Cross-reference of related applications] This application claims priority under Japanese Patent Application No. 2024-206449, filed on 27 November 2024, which is incorporated herein by reference in its entirety. This disclosure relates to radiation-sensitive compositions, methods for forming resist patterns, radiation-sensitive acid generators, and 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] Further miniaturization is rapidly progressing in various electronic device structures, and consequently, further miniaturization of resist patterns in lithography processes is required. In addition, in response to the demand for further miniaturization of resist patterns, various measures are being considered 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).

[0004] Patent Document 1 discloses that an onium salt compound comprising a radiation-sensitive onium cation having two or more substituents selected from the group consisting of fluoroalkyl groups and fluoro groups, and an organic anion having an iodine group, is included in a radiation-sensitive composition as a radiation-sensitive generator to form a resist pattern.

[0005] International Publication No. 2022 / 130869

[0006] Radiation-sensitive compositions used to form resist patterns are sometimes formulated with onium salt-type radiation-sensitive acid generators that generate strong acids upon exposure, or, more recently, structural units derived from radiation-sensitive onium salt compounds are introduced into the base resin. As radiation-sensitive acid generators, sulfonic acid anions with a perfluoroalkyl structure are often used to improve the sensitivity and resolution of the radiation-sensitive composition. On the other hand, due to growing environmental awareness, the development of onium salt compounds with reduced fluorine atom content is being investigated in recent years. Furthermore, given the increasing miniaturization of resist patterns in recent years, there is a need for radiation-sensitive acid generators that reduce fluorine atom content while providing a more sensitive and high-performance radiation-sensitive composition with excellent LWR (Line Width Roughness) capabilities.

[0007] This disclosure has been made in view of the above-mentioned problems, and one objective is to provide a radiation-sensitive composition that is highly sensitive and has excellent LWR performance, and a method for forming a resist pattern using the radiation-sensitive composition. Another objective is to provide a radiation-sensitive acid generator and compound that can produce a radiation-sensitive composition that is highly sensitive and has excellent LWR performance.

[0008] According to this disclosure, in one embodiment, a radiation-sensitive composition is provided that contains a polymer (P) having an acid-dissociable structural unit, and satisfies one or more of the following first and second requirements: First requirement: Further contains a compound represented by the following formula (1). Second requirement: The polymer (P) further contains a structural unit derived from the compound represented by the following formula (1). (In formula (1), R Ａ is a halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (i). Ｂ -CN, hydrogen atom, halogen atom, -NO ２ The group is -OH, -SH, -COOH, or represented by the following formula (i). ＋ (This is a radiation-sensitive onium cation.) (In formula (i), R １is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent group containing one or more groups selected from the group consisting of -O-, -CO- and -SO within the aliphatic ring of the substituted or unsubstituted divalent alicyclic hydrocarbon group ２ is a divalent group containing one or more groups selected from the group consisting of -O-, -CO- and -SO within the aliphatic ring of the substituted or unsubstituted divalent alicyclic hydrocarbon group. R ２ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent group containing one or more groups selected from the group consisting of -O-, -CO- and -SO within the aliphatic ring of the substituted or unsubstituted monovalent alicyclic hydrocarbon group ２ is a monovalent group containing one or more groups selected from the group consisting of -O-, -CO- and -SO within the aliphatic ring of the substituted or unsubstituted monovalent alicyclic hydrocarbon group. R ２ When R has a substituent, the substituent that R ２ has is at least one selected from the group consisting of a halogen atom, a hydroxy group, a carboxy group, a cyano group and a nitro group. X １ is a single bond, -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or a divalent linking group formed by combining two or more selected from the group consisting of -CO-, -O-, -NR ３ -, -SO ２ - and -S-. X ２ is -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or a divalent linking group formed by combining two or more selected from the group consisting of -CO-, -O-, -NR ３ -, -SO ２ - and -S-. R ３ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n is an integer of 0 to 3. When n is 0, R ２ has 2 or more carbon atoms. When n is 2 or more, a plurality of R １ are the same or different, and a plurality of X ２ are the same or different. * represents a bond. )

[0009] According to the present disclosure, in another aspect, there is provided a resist pattern forming method including a step of forming a resist film on a substrate using the above-described radiation-sensitive composition, a step of exposing the resist film, and a step of developing the exposed resist film.

[0010] In another embodiment of this disclosure, a radiation-sensitive acid generator represented by the following formula (1A) is provided. Furthermore, in another embodiment of this disclosure, a compound represented by the following formula (1A) is provided. (In formula (1A), R Ａ is a halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). Ｂ -CN, hydrogen atom, halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). However, R Ｂ In the case of -CN, R Ａ is a halogen atom, -OH, -SH or -COOH, or a group represented by the following formula (ia) (wherein -COOC ２ H ５ and -COO(CH ２ ) ２ (Excluding OH.) Z ＋ (This is a radiation-sensitive onium cation.) (In formula (ia), R １ This is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or the aliphatic ring of a substituted or unsubstituted divalent alicyclic hydrocarbon group contains -O-, -CO-, and -SO3. ２ - A divalent group containing one or more groups selected from the group consisting of -. ２ This is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or an aliphatic ring of a substituted or unsubstituted monovalent alicyclic hydrocarbon group containing -O-, -CO-, and -SO3. ２ - A monovalent group containing one or more groups selected from the group consisting of -. ２ If R has substituents, ２ The substituents on are at least one selected from the group consisting of halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, and nitro groups. １ These are single bonds, -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ２ -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ３ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n is an integer from 0 to 3. If n is 0, R ２ It has 2 or more carbon atoms. When n is 2 or more, multiple R １ They are the same or different, multiple X ２ These are either the same or different. * indicates a combination.

[0011] According to this disclosure, a radiation-sensitive composition that is highly sensitive and has excellent LWR performance can be obtained.

[0012] 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.

[0013] Herein, in this specification, "hydrocarbon group" means a group of hydrocarbons including 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 include 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 include a linear structure or an alicyclic hydrocarbon structure as part of it. "Organic group" means an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). "Aromatic ring" is a term that includes aromatic hydrocarbon rings and aromatic heterocycles. The term "aliphatic hydrocarbon group" encompasses both linear hydrocarbon groups and alicyclic hydrocarbon groups.

[0014] 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."

[0015] 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.

[0016] <<Radiation-sensitive composition>> The radiation-sensitive composition of this disclosure (hereinafter also referred to as "this composition") contains a polymer containing a structural unit having an acid-dissociable group. Furthermore, this composition satisfies one or more of the following first and second requirements. First requirement: Further contains a compound represented by the following formula (1). Second requirement: The polymer containing a structural unit having an acid-dissociable group contains a structural unit derived from the compound represented by the following formula (1). (In formula (1), R Ａ is a halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (i). Ｂ -CN, hydrogen atom, halogen atom, -NO ２ The group is -OH, -SH, -COOH, or represented by the following formula (i). ＋ (This is a radiation-sensitive onium cation.) (In formula (i), R １ This is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or the aliphatic ring of a substituted or unsubstituted divalent alicyclic hydrocarbon group contains -O-, -CO-, and -SO3. ２ - A divalent group containing one or more groups selected from the group consisting of -. ２ This is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or an aliphatic ring of a substituted or unsubstituted monovalent alicyclic hydrocarbon group containing -O-, -CO-, and -SO3. ２- A monovalent group containing one or more groups selected from the group consisting of -. ２ If R has substituents, ２ The substituents on are at least one selected from the group consisting of halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, and nitro groups. １ These are single bonds, -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ２ -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ３ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n is an integer from 0 to 3. If n is 0, R ２ It has 2 or more carbon atoms. When n is 2 or more, multiple R １ They are the same or different, multiple X ２ These are either the same or different. * indicates a combination.

[0017] First, we will explain in detail the compound represented by formula (1) above. In the following, polymers containing structural units with acid-dissociable groups will also be referred to as "polymer (P)," and the compound represented by formula (1) above will also be referred to as "compound (A)."

[0018] <Compound (A)> Compound (A) is a radiation-sensitive acid generator consisting of a radiation-sensitive onium cation and anion, and is represented by the above formula (1). Compound (A) can function as a radiation-sensitive acid generator that generates a strong acid that induces the dissociation of an acid-dissociable group under normal conditions. Compound (A) may be a component that is incorporated into the radiation-sensitive composition separately from the polymer component (i.e., a non-polymer radiation-sensitive acid generator), or it may be a monomer that constitutes the polymer (P). Here, "normal conditions" refers to the conditions under which post-exposure baking (PEB) is performed at 110°C for 60 seconds.

[0019] In the above formula (1), R Ａ or R Ｂ Examples of halogen atoms represented by this formula include fluorine, chlorine, bromine, and iodine atoms.

[0020] In the above equation (i), R ２ Examples of monovalent hydrocarbon groups represented by include monovalent chain 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.

[0021] 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.

[0022] Monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include cyclopentyl group, cyclohexyl group, 1-methyl-1-cyclopentyl group, 3-methyl-1-cyclopentyl group, 1-ethyl-1-cyclopentyl group, 3-ethyl-1-cyclopentyl group, 1-methyl-1-cyclohexyl group, 4-methyl-1-cyclohexyl group, 1-ethyl-1-cyclohexyl group, 4-ethyl-1-cyclohexyl group, cycloheptyl group, cyclooctyl group, and other monovalent groups. Examples include monocyclic alicyclic saturated hydrocarbon groups; monovalent monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl, cyclohexenyl, methylcyclopentenyl, and methylcyclohexenyl groups; monovalent polycyclic alicyclic saturated hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, estranyl, and androstanyl groups; and monovalent polycyclic alicyclic unsaturated hydrocarbon groups such as norborneyl, tricyclodecenyl, indenyl, and indanyl groups.

[0023] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, mesityl, vinylphenyl, naphthyl, methylnaphthyl, anthryl, and methylanthryl; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl.

[0024] R ２ However, in the case of a substituted monovalent hydrocarbon group, examples of substituents include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and the like.

[0025] R ２ However, the aliphatic ring (i.e., the aliphatic hydrocarbon ring) of a substituted or unsubstituted monovalent alicyclic hydrocarbon group contains -O-, -CO-, and -SO ２When it is a monovalent group containing one or more groups selected from the group consisting of (hereinafter also referred to as "monovalent heterocyclic-containing hydrocarbon group"), examples of the aliphatic ring include a monocyclic aliphatic saturated hydrocarbon ring having 3 to 20 carbon atoms, a monocyclic aliphatic unsaturated hydrocarbon ring having 3 to 20 carbon atoms, a polycyclic aliphatic saturated hydrocarbon ring having 6 to 20 carbon atoms, a polycyclic aliphatic unsaturated hydrocarbon ring having 6 to 20 carbon atoms, and the like. When the aliphatic ring is polycyclic, the aliphatic ring may be any of a fused ring, a bridged ring, and a spiro ring, or may be a combination of two or more of a fused ring, a bridged ring, and a spiro ring. In the aliphatic hydrocarbon ring, -O-, -CO-, and -SO ２ Specific examples of the ring structure containing one or more groups selected from the group consisting of include a cyclic ether structure, a lactone structure, a cyclic carbonate structure, a cyclic ketone structure or a sultone structure, or a ring structure combined with two or more selected from the group consisting of a cyclic ether structure, a lactone structure, a cyclic carbonate structure, and a sultone structure.

[0026] Further specific examples of the monovalent heterocyclic-containing hydrocarbon group include -O-, -CO-, and -SO in the aliphatic hydrocarbon ring ２ A group obtained by removing one hydrogen atom from the ring portion of a ring containing one or more groups selected from the group consisting of (hereinafter also referred to as "specific aliphatic heterocyclic ring"); a monovalent group formed by bonding a specific aliphatic heterocyclic ring and an aliphatic hydrocarbon group (including a chain hydrocarbon group and an alicyclic group); When the monovalent heterocyclic-containing hydrocarbon group has a substituent, examples of the substituent include a group similar to the group exemplified as the substituent that R has when it is a monovalent hydrocarbon group substituted by R ２ When it is a monovalent hydrocarbon group substituted by R ２ The groups similar to the groups exemplified as the substituent that R has.

[0027] R １ Examples of the substituted or unsubstituted divalent hydrocarbon group represented by include a group obtained by further removing one hydrogen atom from the substituted or unsubstituted monovalent hydrocarbon group exemplified as a specific example of R. Examples of the divalent group containing one or more groups selected from the group consisting of -O-, -CO-, and -SO in the aliphatic ring of the substituted or unsubstituted monocyclic aliphatic hydrocarbon group represented by R ２ When it is a monovalent alicyclic hydrocarbon group substituted by R １ Examples of the divalent group containing one or more groups selected from the group consisting of -O-, -CO-, and -SO in the aliphatic ring of the substituted or unsubstituted monocyclic aliphatic hydrocarbon group represented by R ２ When it is a divalent group containing one or more groups selected from the group consisting of -O-, -CO-, and -SO in the aliphatic ring of the substituted or unsubstituted monocyclic aliphatic hydrocarbon group represented by R ２Examples thereof include a group obtained by further removing one hydrogen atom from a monovalent hydrocarbon group containing a heterocyclic ring.

[0028] R Ａ is preferably -COOH or a group represented by the above formula (i) in that it can enhance the sensitivity of the present composition and can enhance the improvement effect of LWR performance. From the viewpoint of obtaining a radiation-sensitive composition excellent in LWR performance, n Rs in the formula (i) １ and R ２ The total number of carbon atoms between and is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more. Further, when the group represented by the above formula (i) has a ring structure, it is preferable from the viewpoint of improving LWR performance, and it is more preferable to have one or both of an aliphatic hydrocarbon ring and a specific aliphatic heterocyclic ring. When R Ａ is -COOH, the compound (A) is likely to interact with the resin in the present composition. When R Ａ is a group represented by the above formula (i), R Ａ can have a relatively bulky structure. As a result, it is considered that the diffusion of the compound (A) in the resist film can be suppressed, and as a result, the LWR performance can be improved.

[0029] R Ｂ is preferably -CN, a halogen atom, -NO ２ , -COOH or a group represented by the above formula (i) in that it can further increase the sensitivity of the present composition. Among these, -CN is particularly preferable in that it can improve the LWR performance in a balanced manner while further increasing the sensitivity of the present composition.

[0030] X １ is preferably bonded to the ring to which three or more cyano groups are bonded by -CO- in order to further improve the sensitivity of the present composition. * １ -CO-O-, * １ -CO-NH- or * １ -CO-S- is particularly preferable. * １ represents a bond to the ring to which three or more cyano groups are bonded. X ２ Examples of the divalent linking group represented by include -CO-, -O-, -NH-, -S-, -SO ２Examples include -, -CO-O-, -O-CO-, -CO-NH-, -CO-S-, etc.

[0031] R Ａ and R Ｂ If one or both of the elements have an iodine atom, it is preferable in that the sensitivity of the composition can be further improved. Ａ and R Ｂ The iodine atom in the composition is preferably bonded to an aromatic ring, as this can further enhance the sensitivity-improving effect of the composition. Examples of such aromatic rings include benzene rings and naphthalene rings.

[0032] Further specific examples of anions constituting compound (A) include the anions represented by formulas (a-1) to (a-20) below. Note that the onium salt compound consisting of the anion represented by formula (a-15) and a radiation-sensitive cation, and the onium salt compound consisting of the anion represented by formula (a-16) and a radiation-sensitive cation, are also examples of monomers for obtaining polymer (P) that satisfies the second requirement.

[0033] In the above equation (1), Z ＋ Z is a radiation-sensitive cation. ＋ Examples of radiation-sensitive cations represented by Z include sulfonium cations, iodonium cations, and quaternary ammonium cations. In terms of being able to form a resist film with excellent CDU (Critical Dimension Uniformity) performance and LWR performance, Z ＋ Of these, sulfonium cations or iodonium cations are preferred, and arylsulfonium cations or aryliodonium cations are more preferred. In arylsulfonium cations or aryliodonium cations, S ＋ Or I ＋ Examples of aromatic rings that can be bonded include benzene rings, naphthalene rings, anthracene rings, and thiophene rings. S in arylsulfonium cations ＋ or I in aryliodonium cation ＋ Of these, the aromatic ring bonded is preferably a benzene ring or a naphthalene ring.

[0034] In terms of being able to increase the sensitivity of this composition, Z ＋ It is preferable that the molecule has an aromatic ring, and that a halogen group is bonded to the aromatic ring. Examples of halogen groups include fluoro groups, bromo groups, chloro groups, and iodo groups. The number of halogen groups bonded to the aromatic ring (the total number if two or more types of halogen groups are bonded) should be one or more per molecule. ＋ The number of halogen groups present is preferably two or more, as this can increase the sensitivity of the radiation-sensitive composition. Also, Z ＋ From the viewpoint of balancing the ease of synthesis of the compound with the effects of introducing halogen groups, the number of halogen groups present is preferably 10 or less, and more preferably 8 or less.

[0035] Z ＋ Preferred specific examples of the radiation-sensitive cation represented by the formula (5), formula (6), or formula (7) below include the cation represented by the formula (5), formula (6), or formula (7). (In formula (5), R １ａ and R ２ａ These are either monovalent substituents independently of each other, or R １ａ and R ２ａ These represent single or divalent groups that combine with each other to form a ring. 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 × (r1) + 5). r1 is 0 or 1. In formula (6), R ４ａ and R ５ａ are independent monovalent substituents. a4 and a5 are independent integers from 0 to 5. In formula (7), R ６ａ R is a monovalent substituent. ７ａ is either a monovalent substituent or two R ７ａ This represents a fused ring structure formed by combining elements with each other and the rings they bond together. a6 is an integer from 0 to (2 × (r²) + 5). a7 is an integer from 0 to 4. r² is 0 or 1. L Ｃ is a single bond or a divalent linking group. q is an integer from 0 to 3. In the formula, S ＋The ring structure containing the above may include heteroatoms (oxygen atoms, sulfur atoms, etc.) between the carbon-carbon bonds that form the skeleton.

[0036] In equations (5), (6), and (7) above, R １ａ , R ２ａ , R ３ａ , R ４ａ , R ５ａ , R ６ａ and R ７ａ Examples of monovalent substituents represented by include fluoro groups, chloro groups, bromo groups, iodo groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted cycloalkyl groups, ester groups, alkylsulfonyl groups, cycloalkylsulfonyl groups, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and the like. １ａ ~R ７ａ If the compound has substituents, examples of substituents include fluoro groups, chloro groups, bromo groups, iodo groups, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and alkoxy groups having 1 to 5 carbon atoms.

[0037] R １ａ and R ２ａ When the elements are joined together to form a ring that connects them, R １ａ and R ２ａ Preferably, the bond is a single bond connecting the rings, or it forms an -O- or -S- bond.

[0038] Z ＋ Further specific examples of radiation-sensitive cations represented by the formula below include, for example, cations represented by the following formula. However, radiation-sensitive cations are not limited to those listed below.

[0039] Further specific examples of compound (A) include onium salt compounds obtained by arbitrarily combining the anions and radiation-sensitive cations exemplified above. However, compound (A) is not limited to these specific examples.

[0040] A preferred embodiment of this composition is a polymer composition containing a polymer (P) and a non-polymer radiation-sensitive acid generator. The non-polymer radiation-sensitive acid generator may be a radiation-sensitive acid generator, an acid diffusion control agent, or both. Preferred specific embodiments of this composition include the following embodiments (I) and (II): Embodiment (I): An embodiment containing a polymer (P), a radiation-sensitive acid generator, and an acid diffusion control agent, wherein the radiation-sensitive acid generator is compound (A). Embodiment (II): An embodiment containing a polymer (P) and an acid diffusion control agent, wherein the polymer (P) contains structural units derived from compound (A).

[0041] Each of embodiments (I) and (II) may further contain other components. For example, the radiation-sensitive composition of embodiment (II) may further contain a radiation-sensitive acid generator. Also, the radiation-sensitive compositions of embodiments (I) and (II) may further contain components other than polymer (P) and radiation-sensitive acid generator. Furthermore, the composition may contain polymer (P) which includes structural units derived from compound (A) and compound (A). For example, the polymer (P) contained in the radiation-sensitive composition of embodiment (I) may further contain structural units derived from compound (A). The acid diffusion control agent of embodiments (I) and (II) corresponds to "an onium salt compound that generates an acid with lower acidity than the compound represented by formula (1) above upon exposure."

[0042] Next, the components included in this composition and optionally added components will be described in detail. This composition contains a polymer (P) and may further contain one or more components selected from the group consisting of a radiation-sensitive acid generator, an acid diffusion control agent, a high-fluorine-content polymer, and a solvent as preferred components. Unless otherwise specified, each component included in this composition may be used alone or in combination of two or more.

[0043] <Polymer (P)> The acid-dissociable groups of polymer (P) are groups that substitute for hydrogen atoms in acidic groups such as carboxyl groups and hydroxyl groups, and are groups that dissociate under the action of acid. By including a polymer having acid-dissociable groups in this composition, the acid-dissociable groups dissociate due to the acid generated by exposure of the composition, producing acidic groups, thereby changing the solubility of the polymer components in the developer in the exposed area. As a result, good lithography properties can be imparted to this composition. It is preferable that polymer (P) includes structural units having acid-dissociable groups in order to sufficiently increase the difference in dissolution rates in the developer between the exposed and unexposed areas. Hereinafter, the structural units having acid-dissociable groups contained in polymer (P) will also be referred to as "first structural units".

[0044] (First structural unit) The first structural unit only needs to have an acid-dissociable group, and the structure of the other parts is not particularly limited. Examples of the first structural unit include the structural unit represented by the following formula (2-1) (hereinafter also referred to as "structural unit (1-A)"), the structural unit represented by the following formula (2-2) (hereinafter also referred to as "structural unit (1-B)"), and the structural unit represented by the following formula (2-3) (hereinafter also referred to as "structural unit (1-C)"). (In formula (2-1), R ３０ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ３ R is a divalent chain-like organic group or an alicyclic hydrocarbon group. ３１ R is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３２ and R ３３ 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 ３２ and R ３３ When they are combined with each other, R ３２ and R ３３ R represents an alicyclic hydrocarbon structure or aliphatic heterocyclic structure with 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded. ３１ If R is a hydrogen atom, ３２ and R ３３Either or both of them are independently a substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, a monovalent aromatic heterocyclic group, or R ３２ and R ３３ When they are combined with each other, R ３２ and R ３３ R represents a cyclic unsaturated hydrocarbon structure or an aliphatic heterocyclic structure with 3 to 20 carbon atoms, formed together with the bonded carbon atoms. g1 is 0 or 1. In formula (2-2), R ３０ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ４ These are single bonds, -O-, -CO-, and * ２ -COO- or * ２ -CONH-. "* ２ The symbol " represents a bond to the main chain. ３４ , R ３５ and R ３６ 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. ２８ is a monovalent substituent. g2 is an integer from 0 to 4. In formula (2-3), R ３０ L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ５ These are single bonds, -O-, -CO-, and * ３ -COO- or * ３ -CONH-. "* ３ The symbol " represents a bond to the main chain. ３７ 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. ３８ and R ３９ 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 ３８ and R ３９ They are combined with each other R ３８ and R ３９This represents an alicyclic hydrocarbon structure with 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded. ２９ (where g3 is an integer between 0 and 4.)

[0045] In the above equation (2-1), R ３０ From the viewpoint of copolymerizability of the monomer that gives structural unit (1-A), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred. In the above formula (2-2), R ３０ From the viewpoint of copolymerizability of the monomer that gives structural unit (1-B), a hydrogen atom is preferred. Similarly, in the above formula (2-3), R ３０ The hydrogen atom or methyl group is preferred. In the above formula (2-2), L ４ or L in formula (2-3) ５ A single bond, -COO-, or -CONH- is preferred.

[0046] In the above formula (2-1), L ３ Divalent chain organic groups represented by include divalent saturated chain hydrocarbon groups having 1 to 20 carbon atoms, and divalent saturated chain hydrocarbon groups 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 are replaced by (-). Divalent saturated chain hydrocarbon groups with 1 to 20 carbon atoms may be linear or branched.

[0047] In equations (2-1) to (2-3) above, R ３１ ~R ３３ , R ３４ ~R ３６ or R ３７ ~R ３９ Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms 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.

[0048] Specific examples of 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 include R in formula (i) above. ２Examples of monovalent hydrocarbon groups include those similar to those exemplified. Examples of monovalent aromatic heterocyclic groups include the furyl group and the thienyl group.

[0049] R ３２ and R ３３ When they are combined with each other, R ３２ and R ３３ A cycloaliphatic hydrocarbon structure having 3 to 20 carbon atoms, formed together with the carbon atoms to which it is bonded, and R ３８ and R ３９ When they are combined with each other, R ３８ and R ３９ Examples of alicyclic hydrocarbon structures having 3 to 20 carbon atoms, formed together with the carbon atoms to which the alicyclic atoms are bonded, include monocyclic saturated alicyclic structures such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; monocyclic unsaturated alicyclic structures such as cyclopentene and cyclohexene; and polycyclic alicyclic structures such as norbornane, adamantane, tricyclodecane, and tetracyclododecane.

[0050] R ３１ , R ３５ , R ３６ , R ３７ , R ３８ or R ３９ Examples of monovalent oxy hydrocarbon groups having 1 to 20 carbon atoms represented by the above R ３１ Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include groups having an oxygen atom at the end of the bonded side of the group exemplified above. ３４ Of the monovalent oxy hydrocarbon groups represented by the above, alkoxy groups, cycloalkoxy groups, or cycloalkylalkoxy groups are preferred.

[0051] R ３１ ~R ３９ 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. ２８ or R ２９Examples of monovalent substituents represented by include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), substituted or unsubstituted monovalent hydrocarbon groups, substituted or unsubstituted monovalent oxyhydrocarbon groups, ester groups (-COOR, where R is an alkyl group having 1 to 3 carbon atoms), alkylsulfonyl groups, cycloalkylsulfonyl groups, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, etc. When one or more hydrogen atoms of a monovalent hydrocarbon group or monovalent oxyhydrocarbon group are substituted, examples of substituents include halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, etc. g1 and g2 are preferably 0 to 2.

[0052] Specific examples of the first structural unit include the structural unit represented by the following formula. However, the first structural unit is not limited to the following specific examples. In the following formula, R ３０ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0053] • Structural unit (1-A)

[0054] • Structural unit (1-B)

[0055] • Structural unit (1-C)

[0056] In polymer (P), the content of the first structural unit is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more, relative to the total structural units constituting polymer (P). Furthermore, the content of the first structural unit is preferably 85 mol% or less, and more preferably 75 mol% or less, relative to the total structural units constituting polymer (P). By setting the content of the first structural unit within the above range, the difference in dissolution rate between the exposed and unexposed areas in the developer can be sufficiently large, and the pattern shape of the resist film can be improved.

[0057] The polymer (P) may contain structural units other than the first structural unit (hereinafter also referred to as "other structural units"). Examples of other structural units include the following second, third, fourth, and fifth structural units.

[0058] (Second Structural Unit) The polymer (P) may further contain structural units having a lactone structure, a cyclic carbonate structure, a sultone structure, or a ring structure formed by combining two or more types selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures (excluding those corresponding to the first structural unit or structural units derived from a radiation-sensitive onium salt; hereinafter also referred to as the "second structural unit"). By introducing the second structural unit into the polymer (P), the solubility in the developer can be adjusted, and as a result, the lithography properties of this composition can be further improved. In addition, by including the second structural unit in the polymer (P), the adhesion between the resist film obtained using this composition and the substrate can be improved.

[0059] Examples of the second structural unit include 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.)

[0060] When the polymer (P) contains a second structural unit, the content of the second structural unit is preferably 5 mol% or more, and more preferably 10 mol% or more, relative to the total structural units constituting the polymer (P). Furthermore, the content of the second structural unit is preferably 85 mol% or less, and more preferably 75 mol% or less, relative to the total structural units constituting the polymer (P). Setting the content of the second structural unit within the above range is advantageous in that it can improve the lithography properties of the composition and improve the adhesion of the resist film obtained using the composition to the substrate.

[0061] (Third Structural Unit) The polymer (P) may further contain structural units having an aromatic ring and a hydroxyl group bonded to the aromatic ring (excluding those corresponding to the first structural unit, the second structural unit, or structural units derived from a radiation-sensitive onium salt; these are referred to as the "third structural unit"). By having a hydroxyl group bonded to the aromatic ring in the polymer (P), the CDU performance and LWR performance of the composition can be further improved, and the effect of suppressing dissolution of unexposed areas into the developer is enhanced, allowing for a sufficient reduction in defects. Furthermore, the polymer (P) containing the third structural unit can be preferably used in pattern formation using exposure with radiation of wavelength 50 nm or less, such as electron beams and EUV.

[0062] Furthermore, the third structural unit differs from the first structural unit in that it does not have an acid-dissociable group, and it differs from the fourth structural unit shown below in that it does not have a substructure derived from a radioactive onium salt. In this specification, structural units having an acid-dissociable group and a hydroxyl group bonded to an aromatic ring are classified as the first structural unit.

[0063] A preferred example of the third structural unit is the structural unit represented by the following formula (3). (In formula (3), 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.

[0064] In the above formula (3), R ５０ From the viewpoint of copolymerization of the monomer that gives the third structural unit, 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 the third structural unit, A １０The aromatic ring present is preferably a benzene ring or a naphthalene ring, with a benzene ring being more preferable.

[0065] The position of the hydroxyl group bonded to the aromatic ring is not particularly limited. For example, if the third structural unit has a hydroxyl group bonded to a benzene ring, the bonded position of the hydroxyl group on the benzene ring in the third structural unit is not limited to other groups (L ２ ) may be in the ortho, meta, or para position.

[0066] 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, and monovalent oxyhydrocarbon groups. n1 is preferably 1 to 3, and 1 or 2 is preferred. n2 is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0067] Specific examples of the third structural unit include the structural units represented by each of the following formulas. However, the third structural unit is not limited to these specific examples. (In the formula, R ５０ (This is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group.)

[0068] In polymer (P), the content of the third structural unit is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, relative to the total amount of structural units in polymer (P). Furthermore, the content of the third structural unit is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less, relative to the total amount of structural units in polymer (P). By setting the content of the third structural unit within the above range, the lithography characteristics of this composition, such as LWR performance and CDU performance, can be further improved, and defects can be sufficiently reduced.

[0069] (Fourth Structural Unit) The polymer (P) may further contain structural units derived from a radiation-sensitive onium salt (referred to as the "fourth structural unit"). The fourth structural unit is typically a structural unit derived from a monomer consisting of a radiation-sensitive onium cation and an organic anion. It is thought that the fourth structural unit releases an organic anion when the radiation-sensitive onium cation decomposes under the action of radiation, and that the released organic anion combines with hydrogen extracted from components contained in the composition (e.g., radiation-sensitive acid generators, acid diffusion controllers, solvents, etc.) to produce an acid derived from the organic anion. Examples of organic anions include sulfonic acid anions, carboxylic acid anions, and sulfonimide anions.

[0070] Examples of monomers that give the fourth structural unit include onium salt compounds consisting of a sulfonic acid anion or carboxylic acid anion and a radiation-sensitive cation. The fourth structural unit is the negatively charged portion (-SO) of the organic anion. ３ － Ya-COO － The ) may be bonded to the main chain of the polymer via a linking group, and the radiation-sensitive onium cation may form a counterion. Alternatively, the positively charged portion of the radiation-sensitive onium cation may be bonded to the main chain of the polymer via a linking group, and the organic anion may form a counterion. In order to improve the lithographic performance of this composition, it is preferable that the negatively charged portion of the organic anion in the fourth structural unit is bonded to the main chain of the polymer via a linking group, and the sulfonate anion -SO ３ － or the -COO carboxylate anion － It is more preferable that the organic anion is bonded to the main chain of the polymer via a linking group. From the viewpoint of ease of synthesis of monomers and polymers, the organic anion in the fourth structural unit is preferably a sulfonic acid anion.

[0071] From the viewpoint of increasing the sensitivity of the composition, the radiation-sensitive cation in the fourth structural unit is preferably a sulfonium cation or an iodonium cation, and more preferably a triarylsulfonium cation or a diaryliodonium cation. Furthermore, the monomer giving the fourth structural unit may be compound (A), and the anion in the monomer giving the fourth structural unit may be composed of the sulfonic acid anion in formula (1) above.

[0072] From the viewpoint of increasing the sensitivity of this composition, the aromatic ring (i.e., S) of the triarylsulfonium cation or diaryliodonium cation is ＋ Or I ＋ The aromatic ring bonded to the atom preferably has at least one of the following groups bonded to it: an iodine group, a fluoro group (excluding the fluoro group in a fluoroalkyl group), and a fluoroalkyl group. The fluoroalkyl group is preferably a trifluoromethyl group.

[0073] Specific examples of the fourth structural unit include the structural unit represented by the following formula. However, the fourth structural unit is not limited to these specific examples. (In the formula, R ４０ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＋ This is a sulfonium cation or an iodonium cation. － (This is a sulfonate anion or a carboxylic acid anion.)

[0074] When polymer (P) contains a fourth structural unit, the content of the fourth structural unit in polymer (P) is preferably 1 mol% or more, and more preferably 5 mol% or more, relative to the total amount of structural units in polymer (P). Furthermore, the content of the fourth structural unit in polymer (P) is preferably 30 mol% or less, and more preferably 25 mol% or less, relative to the total amount of structural units in polymer (P). By setting the content of the fourth structural unit within the above range, the effect of improving the sensitivity of this composition by introducing the fourth structural unit can be sufficiently obtained.

[0075] (Fifth structural unit) The polymer (P) may further contain structural units having an alcoholic hydroxyl group (excluding those corresponding to the first to fourth structural units; hereinafter also referred to as the "fifth structural unit"). Hereinafter, the "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). By further containing the fifth structural unit in the polymer (P), the solubility of the polymer (P) in the developer can be improved, and as a result, the lithography performance of the composition can be further improved.

[0076] Specific examples of the fifth structural unit include, for example, the structural unit represented by the following formula. (In the formula, R Ｌ２ (This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.)

[0077] When the polymer (P) contains a fifth structural unit, the content of the fifth structural unit is preferably 1 mol% or more, and more preferably 3 mol% or more, relative to the total structural units constituting the polymer (P). Furthermore, the content of the fifth structural unit is preferably 30 mol% or less, and more preferably 20 mol% or less, relative to the total structural units constituting the polymer (P).

[0078] Other structural units of polymer (P) include, in addition to those mentioned above, structural units having a cyano group (specifically, structural units derived from 2-cyanomethyladamantan-2-yl(meth)acrylate, etc.); structural units containing non-acid-dissociable hydrocarbon groups (specifically, structural units derived from styrene or halogenated styrene, structural units derived from (meth)acrylic acid esters having an alicyclic structure, structural units derived from vinylnaphthalene, structural units derived from n-alkyl(meth)acrylate, etc.). Examples of structural units derived from styrene or halogenated styrene include styrene units, bromostyrene units, iodostyrene units, etc. The content ratio of these structural units can be appropriately set according to each structural unit, within a range that does not impair the effects of the present invention. Polymer (P) can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a known radical polymerization initiator, etc.

[0079] The weight-average molecular weight (Mw) of polymer (P) in terms of polystyrene, determined by gel permeation chromatography (GPC), is preferably 1,200 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 in that it improves the coating properties of the composition and sufficiently suppresses development defects.

[0080] 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, the Mw / Mn of the polymer (P) is usually 1.0 or more.

[0081] The polymer (P) is preferably incorporated into the composition as at least a portion of the base resin. In the composition, the content of polymer (P) is preferably 35% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total amount of solids contained in the composition. In this specification, "solids" refers to the components other than the solvent among the components incorporated into the composition.

[0082] <Radiation-sensitive acid generator> This composition preferably contains a radiation-sensitive acid generator together with the polymer (P). By further including a radiation-sensitive acid generator in this composition, a radiation-sensitive composition with superior lithography performance can be obtained while achieving high sensitivity. Non-polymers are preferably used as radiation-sensitive acid generators because they offer a high degree of freedom in selecting the radiation-sensitive acid generator to be included in this composition and because the amount can be easily adjusted. The molecular weight of the radiation-sensitive acid generator to be included in this composition is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0083] The radiation-sensitive acid generator contained in this composition may be compound (A), or a different compound (hereinafter also referred to as "other acid generator"), as long as this composition satisfies at least one of the first and second requirements. Furthermore, this composition may contain both compound (A) and other acid generators as radiation-sensitive acid generators.

[0084] Other acid generators include onium salt compounds consisting of an organic anion different from the anion in formula (1) above and a radiation-sensitive cation. A sulfonic acid anion is preferably used as the anion constituting the other acid generator. Examples of radiation-sensitive cations constituting the other acid generator include sulfonium cations, iodonium cations, tetrahydrothiophenium cations, and quaternary ammonium cations. Specific examples of radiation-sensitive cations constituting the other acid generators include cations similar to those exemplified as the radiation-sensitive cation constituting compound (A).

[0085] When this composition contains a radiation-sensitive acid generator, it is preferable to use compound (A) alone as the radiation-sensitive acid generator, or to use compound (A) in combination with other acid generators. When compound (A) and other acid generators are used in combination as the radiation-sensitive acid generator, the content of compound (A) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, based on the total amount of compound (A) and other acid generators.

[0086] When a radiation-sensitive acid generator is incorporated into this composition, the content of the radiation-sensitive acid generator in this composition is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of polymer (P), in order to improve the lithography performance of this composition. Furthermore, from the viewpoint of suppressing the occurrence of defects caused by an excessive amount of radiation-sensitive acid generator, the content of the radiation-sensitive acid generator is preferably 60 parts by mass or less, and more preferably 50 parts by mass or less, per 100 parts by mass of polymer (P).

[0087] <Acid Diffusion Control Agent> It is preferable that this composition contains an acid diffusion control agent together with the polymer (P). The acid diffusion control agent is a component that controls the diffusion phenomenon of acid generated from a radiation-sensitive acid generator, etc., in the resist film upon exposure, thereby suppressing chemical reactions by acid in unexposed areas. The inclusion of an acid diffusion control agent in this composition offers advantages such as improved storage stability of the composition, improved resolution of the resist pattern, and suppression of line width changes in the resist pattern due to variations in the holding time from exposure to development.

[0088] Nonpolymers are preferably used as acid diffusion control agents because they offer a high degree of freedom in selecting the acid diffusion control agent to be included in this composition and because their amount can be easily adjusted. The molecular weight of the acid diffusion control agent included in this composition is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0089] Examples of acid diffusion control agents include non-radiation-sensitive compounds and radiation-sensitive onium salts. Examples of non-radiation-sensitive compounds include nitrogen-containing compounds such as n-hexylamine, triethylamine, aniline, ethylenediamine, 2,6-diisopropylaniline, N,N,N',N'-tetramethylethylenediamine, and polyethyleneimine; amide group-containing compounds such as formamide and N,N-dimethylformamide; urea compounds such as urea and dimethylurea; nitrogen-containing heterocyclic compounds such as pyridine and N-propylmorpholine; and acid-dissociable group-containing compounds such as N-t-butoxycarbonylpiperidine, N-(tert-butoxycarbonyl)-4-hydroxypiperidine, and N-(t-butoxycarbonyl)di-n-octylamine.

[0090] When the acid diffusion control agent is a radiation-sensitive onium salt, specific examples of the radiation-sensitive cation constituting the radiation-sensitive onium salt include the same cations as those exemplified as the radiation-sensitive cation constituting compound (A). Furthermore, the anion constituting the acid diffusion control agent is not particularly limited, and is preferably an acid that is less acidic than the acid generated by compound (A) when exposed to light. Examples of anions constituting the acid diffusion control agent when it is a radiation-sensitive onium salt include carboxylic acid anions, sulfonic acid anions, sulfonamide anions, etc. Known anions can be used for these, and for example, an anion represented by the following formula can be used.

[0091] Furthermore, the radiation-sensitive onium salt used as an acid diffusion control agent may be an intramolecular salt. Radiation-sensitive onium salts are preferred as acid diffusion control agents because they offer a higher effect in improving the resolution of the resist pattern.

[0092] Furthermore, radiation-sensitive onium salts are classified as either radiation-sensitive acid generators or acid diffusion controllers depending on their relative acidity to other radiation-sensitive onium salts in the radiation-sensitive composition. The degree of acidity can be evaluated by the acid dissociation constant (pKa). For example, the acid dissociation constant of the acid generated by an acid diffusion controller is usually -3 or higher, preferably -1 ≤ pKa ≤ 7, and more preferably 0 ≤ pKa ≤ 5.

[0093] When an acid diffusion control agent is included in the composition, the amount of the acid diffusion control agent in the composition 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), in order to further improve the lithography performance of the composition. Furthermore, the amount of the acid diffusion control agent is preferably 70 parts by mass or less, and more preferably 50 parts by mass or less, per 100 parts by mass of polymer (P).

[0094] When an acid diffusion control agent is included in this composition, the content of the acid diffusion control agent in this composition is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, relative to the total amount of the radiation-sensitive acid generator and the monomer that provides the fourth structural unit in the polymer (P) contained in this composition. Furthermore, the content of the acid diffusion control agent is preferably 90 mol% or less, and more preferably 80 mol% or less, relative to the total amount of the radiation-sensitive acid generator and the monomer that provides the fourth structural unit in the polymer (P) contained in this composition. By setting the content of the acid diffusion control agent within the above range, the lithography performance of this composition can be further improved.

[0095] <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 included in this composition, 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.

[0096] 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 2% by mass or more, even more preferably 4% by mass or more, and particularly preferably 7% by mass or more. Furthermore, the fluorine atom content of polymer (F) is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The fluorine atom content (by mass%) of the polymer is: １３ The polymer structure can be determined by measuring C-NMR spectra, and the formula can be calculated from that structure.

[0097] Examples of structural units containing fluorine atoms in polymer (F) (hereinafter also referred to as "structural unit (f)") include structural unit (fa) and structural unit (fb) as shown below. Polymer (F) may have either structural unit (fa) or structural unit (fb) as structural unit (f), or it may have both structural unit (fa) and structural unit (fb).

[0098] [Structural Unit (fa)] The structural unit (fa) is a structural unit represented by the following formula (8-1). The polymer (F) can adjust its fluorine atom content by having structural units (fa). (In formula (8-1), R Ｃ G is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO ２ It is -O-NH-, -CONH-, or -O-CO-NH-. Ｅ (This refers to a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0099] In the above formula (8-1), R Ｃ From the viewpoint of copolymerization of the monomer that gives the structural unit (fa), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred. Furthermore, from the viewpoint of copolymerization of the monomer that gives the structural unit (fa), single bonds or -COO- are preferred, and -COO- is more preferred.

[0100] R ＥExamples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by R, include those in which some or all of the hydrogen atoms in a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms. Ｅ Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by R, include monocyclic or polycyclic alicyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms are substituted with fluorine atoms. Among these, R Ｅ The group is preferably a monovalent fluorinated chain hydrocarbon group, more preferably a monovalent fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, or a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0101] When the polymer (F) has structural units (fa), the content of structural units (fa) is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, relative to the total structural units constituting the polymer (F). Furthermore, the content of structural units (fa) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, relative to the total structural units constituting the polymer (F). By setting the content of structural units (fa) within the above range, the mass content of fluorine atoms in the polymer (F) can be adjusted more appropriately, further promoting the uneven distribution on the surface of the resist film, thereby further improving the performance improvement effect of the polymer (F) formulation.

[0102] [Structural Unit (fb)] The structural unit (fb) is a structural unit represented by the following formula (8-2). The polymer (F) has improved solubility in alkaline developer due to the presence of the structural unit (fb), thereby further suppressing the occurrence of development defects. (In formula (8-2), R Ｆ R is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. ５９ is a (s+1) valent hydrocarbon group having 1 to 20 carbon atoms, or the R of said hydrocarbon group. ６０It is a group to which an oxygen atom, a sulfur atom, -NR'-, a carbonyl group, -CO-O-, or -CO-NH- is bonded at one end. R' is a hydrogen atom or a monovalent organic group. ６０ X is a single bond or a divalent organic group having 1 to 20 carbon atoms. １２ This is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. １１ These are oxygen atoms, -NR''-, -CO-O-*, or -SO ２ It is -O-*. R'' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" is R ６１ This shows the binding site. ６１ R is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. s is an integer from 1 to 3. However, if s is 2 or 3, multiple R groups are formed. ６０ , X １２ A １１ and R ６１ (These are either the same or different.)

[0103] Structural units (fb) can be divided into those that have alkali-soluble groups and those that have groups that dissociate under the action of alkali, increasing their solubility in alkaline developers (hereinafter also simply referred to as "alkali-dissociable groups").

[0104] If the structural unit (fb) has an alkali-soluble group, R ６１ A is a hydrogen atom, １１ This is an oxygen atom, -COO-* or -SO ２ It is O-*. "*" represents R ６１ This indicates the site of binding. １２ This is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. １１ If X is an oxygen atom, １２ is, A １１ R is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which it is bonded. ６０ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, there are multiple R ６０ , X １２ A １１ and R ６１These are either identical or different from each other. The structural unit (fb) having an alkali-soluble group increases its affinity for alkaline developers and suppresses development defects.

[0105] If the structural unit (fb) has an alkali-dissociable group, R ６１ A is a monovalent organic group having 1 to 30 carbon atoms. １１ is an oxygen atom, -NR''-, -COO-*, or -SO ２ It is O-*. "*" represents R ６１ This indicates the site of binding. １２ R is a single bond or a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. ６０ A is a single bond or a divalent organic group having 1 to 20 carbon atoms. １１ ga -COO-* or -SO ２ If O - *, then X １２ or R ６１ is, A １１ It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. １１ If X is an oxygen atom, １２ or R ６０ It is a single bond, R ５９ R is a hydrocarbon group having 1 to 20 carbon atoms. ６０ It is a structure in which a carbonyl group is bonded to the terminal end, R ６１ is an organic group having a fluorine atom. When s is 2 or 3, multiple R ６０ , X １２ A １１ and R ６１ Each of these is either identical or different from the others. The presence of an alkali-dissociable group in the structural unit (fb) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. This increases the affinity to the developer, allowing for more efficient suppression of development defects. Examples of structural units (fb) having an alkali-dissociable group include A. １１ ga -COO-*, R ６１ Or X １２ Alternatively, it is particularly preferable that both of these have fluorine atoms.

[0106] When the polymer (F) has structural units (fb), the content of structural units (fb) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, relative to the total structural units constituting the polymer (F). Furthermore, the content of structural units (fb) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, relative to the total structural units constituting the polymer (F). By setting the content of structural units (fb) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0107] The polymer (F) may also contain structural units (fa) and (fb), as well as structural units having acid-dissociable groups and structural units having an alicyclic hydrocarbon structure represented by the following formula (9) (hereinafter also referred to as "structural unit (G)"). (In the above formula (9), R Ｇ１ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｇ２ (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0108] In the above formula (9), R Ｇ２ As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (3), R １３ ~R １５ Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms can be given.

[0109] When the polymer (F) contains the structural unit represented by formula (9) above, the content of the structural unit is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to the total structural units constituting the polymer (F). Furthermore, the content of the structural unit represented by formula (9) above is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, relative to the total structural units constituting the polymer (F).

[0110] When polymer (F) contains structural units having acid-dissociable groups, the content of these structural units in polymer (F) is preferably 1 mol% or more, and more preferably 2 mol% or more, relative to the total structural units constituting polymer (F). Furthermore, when polymer (F) contains structural units having acid-dissociable groups, the content is preferably 25 mol% or less, and more preferably 20 mol% or less, relative to the total structural units constituting polymer (F). When this composition contains polymer (F) together with polymer (P), polymer (P) may be a base resin and polymer (F) may be an additive component.

[0111] The Mw of polymer (F) determined by GPC is preferably 1,000 or more, more preferably 3,000 or more, and even more preferably 4,000 or more. Furthermore, the Mw of polymer (F) is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 20,000 or less. The molecular weight distribution (Mw / Mn), expressed as the ratio of Mn to Mw determined by GPC of polymer (F), is preferably 1 or more and 5 or less, and more preferably 1 or more and 3 or less.

[0112] If the composition contains polymer (F), the content of polymer (F) in the composition is preferably 0.1 parts by mass or more, and more preferably 0.2 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, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of polymer (P).

[0113] <Solvent> The solvent is preferably a solvent capable of dissolving or dispersing the components incorporated into this composition. Organic solvents are preferably used as the solvent. Specific examples of solvents include alcohols, ethers, ketones, amides, esters, hydrocarbons, and the like.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] <Other Optional Components> This composition may further contain components other than polymer (P), radiation-sensitive acid generator, acid diffusion control agent, polymer (F), and solvent (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 solvation accelerators.

[0119] <Method for Producing Radiation-Sensitive Composition> This composition can be produced by mixing a polymer (P) and, if necessary, components such as a solvent 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 this 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 this composition is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less. By setting the solid content concentration of this composition within the above range, good coatability can be achieved and the shape of the resist pattern can be improved.

[0120] The resulting 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.

[0121] ≪Method for Forming a Resist Pattern≫ The resist pattern formation method in this disclosure includes a step of coating the 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 uses the composition to form a resist film, it is possible to form a resist pattern with good sensitivity, reduced defects, and good resolution. Each step will be described below.

[0122] <Coating Process> In the coating process, a resist film is formed on the substrate by coating one side of the substrate with the 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 composition include rotary coating (spin coating), casting coating, and roll coating. After coating, a soft bake (SB, also called pre-bake (PB)) 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.

[0123] <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.

[0124] 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, an acid diffusion control agent, or a polymer (P) containing a fourth structural unit). 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.

[0125] <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.

[0126] 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.

[0127] 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).

[0128] <<Radiation-sensitive acid generator and compound>> The present disclosure provides a compound represented by the following formula (1A). The compound represented by the following formula (1A) makes it possible to obtain a radiation-sensitive composition that can form a resist film that is highly sensitive and has excellent LWR performance. The compound represented by the following formula (1A) is particularly useful as a radiation-sensitive acid generator used for forming resist patterns and the like. (In formula (1A), R Ａ is a halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). Ｂ -CN, hydrogen atom, halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). However, R Ｂ In the case of -CN, R Ａ is a halogen atom, -OH, -SH or -COOH, or a group represented by the following formula (ia) (wherein -COOC ２ H ５ and -COO(CH ２ ) ２ (Excluding OH.) Z ＋ (This is a radiation-sensitive onium cation.) (In formula (ia), R １ This is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or the aliphatic ring of a substituted or unsubstituted divalent alicyclic hydrocarbon group contains -O-, -CO-, and -SO3. ２ - A divalent group containing one or more groups selected from the group consisting of -. ２This is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or an aliphatic ring of a substituted or unsubstituted monovalent alicyclic hydrocarbon group containing -O-, -CO-, and -SO3. ２ - A monovalent group containing one or more groups selected from the group consisting of -. ２ If R has substituents, ２ The substituents on are at least one selected from the group consisting of halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, and nitro groups. １ These are single bonds, -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ２ -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ３ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n is an integer from 0 to 3. If n is 0, R ２ It has 2 or more carbon atoms. When n is 2 or more, multiple R １ They are the same or different, multiple X ２ These are either the same or different. * indicates a combination.

[0129] In the above formula (1A), R Ａ , R Ｂ and Z ＋ Furthermore, R in the above formula (ia) １ , R ２ , X １ , X ２ , R ３ And specific and preferred examples of n are the same as those of formulas (1) and (i) above. In formula (1A) above, the group represented by formula (ia) above is the n R in formula (ia) １ and R ２The total number of carbon atoms is 2 or more, preferably 3 or more, and more preferably 4 or more. Furthermore, if the group represented by formula (ia) has a ring structure, the LWR performance can be improved. The ring structure of the group represented by formula (ia) is preferably an aliphatic hydrocarbon ring and / or a specific aliphatic heterocycle.

[0130] The compound represented by formula (1A) above can be synthesized by appropriately combining standard organic chemistry methods. For example, one synthesis method involves obtaining a metal salt of the tri or tetracyanocyclopentadienyl anion corresponding to the anionic portion in formula (1A), and then reacting it with a sulfonium bromide or the like that gives the cation portion in formula (1A). However, the synthesis method of the compound represented by formula (1A) is not limited to the method described above.

[0131] 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. In the following examples, "parts" and "%" are based on mass unless otherwise specified.

[0132] <Measurement and Analysis Method> [Measurement of Weight-Average Molecular Weight (Mw) and Number-Average Molecular Weight (Mn) of Polymers] 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

[0133] [ １３ [C-NMR analysis] Polymer １３ C-NMR analysis was performed using a nuclear magnetic resonance spectrometer (JEOL Ltd.'s "JNM-Delta400").

[0134] <Synthesis of Onium Salt Compounds> [Example B1] Synthesis of Onium Salt Compound (B-1) Onium salt compound (B-1) was synthesized according to the following synthesis scheme.

[0135] In a reaction vessel, the compound represented by the above formula (XB-1) (3.3 g), triphenylsulfonium bromide (4.4 g), dichloromethane (30 g), and ultrapure water (10 g) were added and stirred at room temperature for 2 hours. The aqueous layer was removed, and the organic layer was washed three times with ultrapure water (10 g). The resulting organic layer was concentrated to dryness to obtain the target onium salt compound (B-1) (6.0 g).

[0136] [Example B2] Synthesis of Onium Salt Compound (B-2) The onium salt compound (B-2) was synthesized according to the following synthesis scheme.

[0137] 3.0 g of the compound represented by formula (XB-1), 6 g of methanol, and 12 g of ultrapure water were added to a reaction vessel. 4.6 g of 20% aqueous sodium hydroxide solution was added, and the mixture was stirred at room temperature for 3 hours. 26 g of 2.0 M aqueous hydrochloric acid and 30 g of ethyl acetate were added, and after stirring for 10 minutes, the organic layer was separated. The obtained organic layer was dried over sodium sulfate, and the solvent was removed by distillation to obtain 2.2 g of the compound represented by formula (XB-2).

[0138] In a reaction vessel, 2.2 g of the compound represented by formula (XB-2), 3.3 g of triphenylsulfonium bromide, 20 g of dichloromethane, and 10 g of ultrapure water were added and the mixture was stirred at room temperature for 2 hours. The aqueous layer was removed, and the organic layer was washed three times with 10 g of ultrapure water. The resulting organic layer was concentrated to dryness to obtain the target onium salt compound (B-2) (3.5 g).

[0139] [Examples B3 to B8] Onium salt compounds represented by the following formulas (B-3) to (B-8) were synthesized in the same manner as in Example B2, except that the raw materials and precursors for the synthesis of onium salt compounds (B-3) to (B-8) were appropriately changed.

[0140] [Example B9] Synthesis of Onium Salt Compound (B-9) The onium salt compound (B-9) was synthesized according to the following synthesis scheme.

[0141] In a reaction vessel, 4.0 g of the compound represented by formula (XB-2), 3.7 g of 1-adamantane methanol, 4.3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.6 g of 4-dimethylaminopyridine (DMAP), and 40 g of tetrahydrofuran were added and the mixture was stirred at room temperature for 10 hours. Then, 40 g of ultrapure water and 80 g of ethyl acetate were added and the mixture was stirred for 10 minutes, after which the organic layer was separated. The obtained organic layer was washed three times with 20 g of ultrapure water, and the organic layer was concentrated to dryness. Next, 40 g of dichloromethane, 5.9 g of triphenylsulfonium bromide, and 20 g of ultrapure water were added to this intermediate and the mixture was stirred at room temperature for 2 hours. The aqueous layer was removed and the organic layer was washed three times with 20 g of ultrapure water. The obtained organic layer was concentrated to dryness and purified by column chromatography to obtain the target compound represented by (B-9) (8.5 g).

[0142] [Examples B10 to B22] Onium salt compounds represented by the following formulas (B-10) to (B-22) were synthesized in the same manner as in Example B9, except that the raw materials and precursors for the synthesis of onium salt compounds (B-10) to (B-22) were appropriately changed.

[0143] <Synthesis of Polymers> The monomers used in the synthesis of each polymer in each example and comparative example are shown below. In the following synthesis examples, unless otherwise specified, "parts by mass" refers to the value when the total mass of the monomers used is 100 parts by mass, and "mol%" refers to the value when the total number of moles of the monomers used is 100 mol%.

[0144]

[0145] [Synthesis Example 1] The monomers (M-2), (M-4), (M-5), (M-9), and (M-14) of polymer (A-1) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 10 / 40 / 20 / 25 / 5 (mol%). AIBN (azobisisobutyronitrile) (4 mol% relative to the total 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdery polymer (A-1). The Mw of polymer (A-1) was 7,700, and the Mw / Mn ratio was 1.55. Furthermore, １３ 13C-NMR analysis revealed that the content percentages of each structural unit derived from (M-2), (M-4), (M-5), (M-9), and (M-14) were 9.4 mol%, 39.4 mol%, 20.1 mol%, 25.1 mol%, and 6.0 mol%, respectively.

[0146] [Synthesis Examples 2-11] Polymers (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the monomers used were of the types and proportions shown in Table 1. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymers are also shown in Table 1. Note that "-" in Table 1 indicates that the corresponding compound was not used (the same applies to subsequent tables).

[0147]

[0148] [Synthesis Example 12] The monomers (M-18) and (M-21) of polymer (A-12) were dissolved in 1-methoxy-2-propanol (200 parts by mass) in a molar ratio of 40 / 60 (mol%), and MAIB (dimethyl 2,2'-azobisisobutyrate) (6 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 1-methoxy-2-propanol was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (500 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass) and then dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the polymer. The resulting solid was filtered and dried at 50°C for 12 hours to obtain a white powdery polymer (A-12). The Mw of polymer (A-12) was 5,400, and the Mw / Mn ratio was 1.57. １３ ¹³C-NMR analysis revealed that the content of each structural unit derived from (M-18) and (M-21) was 41.1 mol% and 58.9 mol%, respectively.

[0149] [Synthesis Examples 13-22] Polymers (A-13) to (A-22) were synthesized in the same manner as in Synthesis Example 12, except that the monomers used were of the types and proportions shown in Table 2. Note that the monomers that give the third structural unit in the polymer were, １３ 13C-NMR analysis confirmed the disappearance of the carbonyl group peak of the acetyl group, indicating that virtually all alkali-dissociable groups had been hydrolyzed to phenolic hydroxyl groups. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymer are shown in Table 2.

[0150] [Synthesis Example 23] Synthesis of polymer (A-23) Monomer (M-21), monomer (M-31), and monomer (M-20) were dissolved in 1-methoxy-2-propanol (200 parts by mass) in a molar ratio of 60 / 30 / 10 (mol%), and MAIB (dimethyl 2,2'-azobisisobutyrate) (6 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 1-methoxy-2-propanol was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (500 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass) and then dried at 50°C for 12 hours to obtain a white powdery polymer (A-23). ​​The Mw of polymer (A-23) was 5,600, and the Mw / Mn ratio was 1.60. １３ 13C-NMR analysis revealed that the content percentages of each structural unit derived from (M-21), (M-31), and (M-20) were 59.5 mol%, 30.4 mol%, and 10.1 mol%, respectively.

[0151] [Synthesis Examples 24, 25] Polymers (A-24) and (A-25) were synthesized in the same manner as in Synthesis Example 23, except that monomers of the types and proportions shown in Table 2 were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymers are also shown in Table 2.

[0152]

[0153] [Synthesis Example 26] Synthesis of high-fluorine-content polymer (F-1) Monomer (M-1), monomer (M-15), and monomer (M-32) were dissolved in 2-butanone (200 parts by mass) in a molar ratio of 20 / 10 / 70 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. A solution of the high-fluorine-content polymer (F-1) was obtained by substituting the solvent with propylene glycol monomethyl ether acetate. The Mw of the high-fluorine-content polymer (F-1) was 7,000, and the Mw / Mn ratio was 1.66. Furthermore, １３ 13C-NMR analysis revealed that the content percentages of each structural unit derived from (M-1), (M-15), and (M-32) were 19.7 mol%, 10.8 mol%, and 69.5 mol%, respectively.

[0154] [Synthesis Examples 27-30] Synthesis of High Fluorine-Content Polymers (F-2) to High Fluorine-Content Polymers (F-5) High fluorine-content polymers (F-2) to high fluorine-content polymers (F-5) were synthesized in the same manner as in Synthesis Example 26, except that monomers of the types and blending ratios shown in Table 3 were used. The content ratio (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained high fluorine-content polymers are shown in accordance with Table 3.

[0155]

[0156] <Preparation of Radiation-Sensitive Composition> A radiation-sensitive composition was prepared using the onium salt compound and polymer synthesized above, as well as the following compounds. [Radiation-Sensitive Acid Generator] b-1 to b-5: Compounds represented by the following formulas (b-1) to (b-5)

[0157] [Acid diffusion control agents] D-1 to D-10: Compounds represented by the following formulas (D-1) to (D-10)

[0158] [Solvents] E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: γ-Butyrolactone E-4: Propylene glycol monomethyl ether acetate E-5: Methyl 2-hydroxyisobutyrate

[0159] [Other additive ingredients] W-1: MEGAFACE EFS-321 (manufactured by DIC Corporation, non-fluorinated surfactant) W-2: BYK-399 (manufactured by Bic Chemie Japan, non-silicone surfactant)

[0160] <Preparation of positive-type radiation-sensitive composition for ArF immersion exposure> [Example 1] 100 parts by mass of (A-1) as a base resin, 10.0 parts by mass of (B-1) as a radiation-sensitive acid generator, 8.0 parts by mass of (D-1) as an acid diffusion control agent, 5.0 parts by mass of (F-1) as a high-fluorine-content polymer, 0.5 parts by mass of (W-1) as other additive components, and 3,400 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) (mass ratio = 2,240 / 960 / 200) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a positive-type radiation-sensitive composition (J-1) for ArF immersion exposure.

[0161] [Examples 2-34 and Comparative Examples 1-4] Positive-type radiation-sensitive compositions for ArF immersion exposure (J-2) to (J-34) and (CJ-1) to (CJ-4) were prepared in the same manner as in Example 1, except that the components of the types and amounts shown in Table 4 were used.

[0162]

[0163] <Formation of a resist pattern using a positive-type radiation-sensitive composition for ArF immersion lithography> A base layer film formation composition ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Corporation), and then heated at 205°C for 60 seconds to form a base layer film with an average thickness of 100 nm. The prepared positive-type radiation-sensitive composition for ArF immersion lithography was then applied to this base layer film using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 150 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed to a 60 nm line-and-space mask pattern using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7). After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (60 nm line-and-space pattern).

[0164] <Evaluation (ArF Immersion Lithography)> The sensitivity, LWR performance, and DOF performance (depth of focus) of resist patterns formed using a positive-type radiation-sensitive composition for ArF immersion lithography were evaluated according to the method described below. The results are shown in Table 5. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0165] [Sensitivity] In forming a resist pattern using a positive-type radiation-sensitive composition for ArF immersion lithography, the exposure amount used to form a 60 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 30 mJ / cm². ２ "Good" is defined as 30 mJ / cm² in the following cases: ２ If the value exceeded a certain point, it was rated as "defective."

[0166] [LWR Performance] A 60 nm line-and-space resist pattern was formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The variation in line width was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line jaggedness (roughness) and better performance. LWR performance was evaluated as "good" if it was 3.0 nm or less, and "poor" if it was greater than 3.0 nm.

[0167] [DOF Performance (Depth of Focus)] In the resist pattern resolved at the optimal exposure amount determined in the sensitivity evaluation above, the dimensions were observed when the focus was changed in the depth direction. The margin in the depth direction in which the pattern dimensions fall within 90% to 110% of the standard without bridging or residue was measured, and this measured value was defined as the depth of focus (nm). A larger depth of focus value indicates better performance. A depth of focus of 120 nm or more was evaluated as "good," and a depth of focus of less than 120 nm was evaluated as "poor."

[0168]

[0169] As is clear from the results in Table 5, the radiation-sensitive compositions of Examples 1 to 34 exhibited good sensitivity, LWR performance, and DOF performance when used in ArF immersion lithography. In contrast, the radiation-sensitive compositions of Comparative Examples 1 to 4 exhibited poor sensitivity, LWR performance, and DOF performance. Therefore, it can be said that when the radiation-sensitive compositions of Examples 1 to 34 are used in ArF immersion lithography, it is possible to form resist patterns with high sensitivity and good LWR and DOF performance.

[0170] <Preparation of Negative Radiation-Sensitive Composition for ArF Immersion Lithography, Formation and Evaluation of Resist Pattern> [Example 35] 100 parts by mass of (A-2) as a base resin, 10.0 parts by mass of (B-9) as a radiation-sensitive acid generator, 8.0 parts by mass of (D-4) as an acid diffusion control agent, 5.0 parts by mass of (F-1) as a high-fluorine-content polymer, 0.5 parts by mass of (W-1) as other additive components, and 3,400 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) (mass ratio = 2,240 / 960 / 200) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a negative radiation-sensitive composition for ArF immersion lithography (J-35).

[0171] A base layer film with an average thickness of 100 nm was formed on a 12-inch silicon wafer by applying a base layer film formation composition ("ARC66" from Brewer Science) using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Corporation) and then heating at 205°C for 60 seconds. On this base layer film, an ArF exposure negative radiation-sensitive composition (J-35) was applied using the same spin coater, and PB (plate blot) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 150 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography system ("TWINSCAN XT-1900i" from ASML Corporation) under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7). After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (80 nm line-and-space resist pattern).

[0172] When a resist pattern was formed using ArF immersion lithography negative-type radiation-sensitive composition (J-35), the sensitivity, LWR performance, and DOF performance were also good.

[0173] <Preparation of positive-type radiation-sensitive composition for ArF-Dry exposure, formation and evaluation of resist pattern> [Example 36] 100 parts by mass of (A-11) as a base resin, 10.0 parts by mass of (B-14) as a radiation-sensitive acid generator, 8.0 parts by mass of (D-5) as an acid diffusion control agent, and 3,400 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) (mass ratio = 2,240 / 960 / 200) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a positive-type radiation-sensitive composition for ArF-Dry exposure (J-36).

[0174] On an 8-inch silicon wafer, a base layer film formation composition (Brewer Science's "ARC29") was applied using a spin coater (Tokyo Electron's "CLEAN TRACK ACT8"), and then heated at 205°C for 60 seconds to form a base layer film with an average thickness of 77 nm. On this base layer film, an ArF-Dry exposure positive-type radiation-sensitive composition (J-36) was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 150 nm was formed by cooling at 23°C for 30 seconds. Next, a resist pattern with a line width of 90 nm line and space was formed on this resist film using an ArF excimer laser exposure system (Nikon's "S306C") under optical conditions of NA = 0.75 and Annular (σ = 0.8 / 0.6). After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (80 nm line-and-space resist pattern).

[0175] When a resist pattern was formed using the ArF-Dry exposure positive-type radiation-sensitive composition (J-36), the sensitivity, LWR performance, and DOF performance were also good.

[0176] <Preparation of a positive-type radiation-sensitive composition for extreme ultraviolet (EUV) exposure> [Example 37] A positive-type radiation-sensitive composition for EUV exposure (J-37) was prepared by mixing 100 parts by mass of (A-12) as a base resin, 25.0 parts by mass of (B-9) as a radiation-sensitive acid generator, 25.0 parts by mass of (D-2) as an acid diffusion control agent, and 5,500 parts by mass of a mixed solvent of (E-4) / (E-5) (mass ratio = 3,500 / 2,000) and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0177] [Examples 38-71 and Comparative Examples 5-8] Positive-type radiation-sensitive compositions for EUV exposure (J-38) to (J-71) and (CJ-5) to (CJ-8) were prepared in the same manner as in Example 37, except that the components of the types and amounts shown in Table 6 were used.

[0178]

[0179] <Formation of a resist pattern using a positive-type radiation-sensitive composition for EUV exposure> A base layer film was formed on a 12-inch silicon wafer by applying a base layer film formation composition ("ARC66" from Brewer Science) using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Corporation), and then heating at 205°C for 60 seconds to form a base layer film with an average thickness of 105 nm. On this base layer film, a positive-type radiation-sensitive composition for EUV exposure was applied using the same spin coater, and PB (plate blot) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 50 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus ("NXE3300" from ASML Corporation) with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (20 nm line and space pattern).

[0180] <Evaluation (EUV Exposure)> The sensitivity and LWR performance of resist patterns formed using a positive-type radiation-sensitive composition for EUV exposure were evaluated according to the method described below. The results are shown in Table 7. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist s-pattern.

[0181] [Sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive composition for EUV exposure, the exposure amount used to form a 20 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 50 mJ / cm². ２ If less than 50 mJ / cm², it is considered "good". ２ In the above cases, the product was evaluated as "defective."

[0182] [LWR Performance] The mask size was adjusted to form a 20 nm line-and-space pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above and evaluated in the same manner as in the case of ArF immersion lithography.

[0183]

[0184] As is clear from the results in Table 7, the radiation-sensitive compositions of Examples 37 to 71 exhibited good sensitivity and LWR performance when used in EUV exposure. In contrast, the radiation-sensitive compositions of Comparative Examples 5 to 6 failed to satisfy all of these characteristics simultaneously. In particular, a significant difference was observed in LWR performance between Examples 37 to 71 and Comparative Examples 5 to 8. From these results, it can be said that when the radiation-sensitive compositions of Examples 37 to 71 are used in EUV exposure, it is possible to form resist patterns with high sensitivity and good LWR performance.

[0185] <Preparation of Negative Radiation-Sensitive Composition for EUV Exposure, Formation and Evaluation of Resist Pattern> [Example 72] A negative radiation-sensitive composition for EUV exposure (J-72) was prepared by mixing 100 parts by mass of (A-15) as a base resin, 5.0 parts by mass of (B-12) as a radiation-sensitive acid generator, 18.0 parts by mass of (D-4) as an acid diffusion control agent, 3.0 parts by mass (solids) of (F-5) as a high fluorine-content polymer, and 6,110 parts by mass (mass ratio = 4,280 / 1,830) of a mixed solvent of (E-1) / (E-2) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0186] A base layer film with an average thickness of 105 nm was formed on a 12-inch silicon wafer by applying a base layer film formation composition (Brewer Science's "ARC66") using a spin coater (Tokyo Electron's "CLEAN TRACK ACT12") and then heating at 205°C for 60 seconds. On this base layer film, a negative-type radiation-sensitive composition for EUV exposure (J-72) was applied using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus (ASML's "NXE3300") with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (20 nm line and space pattern).

[0187] The sensitivity, LWR performance, and DOF performance of the resist pattern using the negative-type radiation-sensitive composition for EUV exposure (J-72) were evaluated in the same manner as the evaluation of the resist pattern using the negative-type radiation-sensitive composition for ArF immersion exposure. As a result, the radiation-sensitive resin composition of Example 72 showed good sensitivity, LWR performance, and DOF performance even when a negative-type resist pattern was formed by EUV exposure.

[0188] The radiation-sensitive composition, pattern formation method, polymer, and compound described above can form a resist pattern with good sensitivity to exposure light and excellent LWR and DOF performance. Therefore, the radiation-sensitive composition, pattern formation method, polymer, and compound of this disclosure can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. A radiation-sensitive composition containing a polymer (P) having a structural unit with an acid-dissociable group and satisfying one or more of the following first and second requirements. First requirement: Further containing a compound represented by the following formula (1). Second requirement: The polymer (P) further contains a structural unit derived from the compound represented by the following formula (1). (In formula (1), R Ａ is a halogen atom, -NO ２ , -OH, -SH, -COOH, or a group represented by the following formula (i). R Ｂ is -CN, a hydrogen atom, a halogen atom, -NO ２ , -OH, -SH, -COOH, or a group represented by the following formula (i). Z ＋ is a radiation-sensitive onium cation.) (In formula (i), R １ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent group containing one or more groups selected from the group consisting of -O-, -CO-, and -SO ２ - in the aliphatic ring of a substituted or unsubstituted divalent alicyclic hydrocarbon group. R ２ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent group containing one or more groups selected from the group consisting of -O-, -CO-, and -SO ２ - in the aliphatic ring of a substituted or unsubstituted monovalent alicyclic hydrocarbon group. When R ２ has a substituent, the substituent of R ２ is at least one selected from the group consisting of a halogen atom, a hydroxy group, a carboxy group, a cyano group, and a nitro group. X １ is a single bond, -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or a divalent linking group formed by combining two or more selected from the group consisting of -CO-, -O-, -NR ３ -, -SO ２ - and -S-. X ２ is -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or a divalent linking group formed by combining two or more selected from the group consisting of -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ３ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n is an integer from 0 to 3. If n is 0, R ２ It has 2 or more carbon atoms. When n is 2 or more, multiple R １ They are the same or different, multiple X ２ These are either the same or different. * indicates a combination.

2. Z in equation (1) above ＋ The radiation-sensitive composition according to claim 1, wherein the cation is a sulfonium cation or an iodonium cation.

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

4. The radiation-sensitive composition according to claim 1, further comprising an onium salt that generates an acid less acidic than the compound represented by formula (1) above upon exposure.

5. 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 4; exposing the resist film; and developing the exposed resist film.

6. A radiation-sensitive acid generator represented by the following formula (1A). (In formula (1A), R Ａ is a halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). Ｂ -CN, hydrogen atom, halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). However, R Ｂ In the case of -CN, R Ａ is a halogen atom, -OH, -SH or -COOH, or a group represented by the following formula (ia) (wherein -COOC ２ H ５ and -COO(CH ２ ) ２ (Excluding OH.) Z ＋ (This is a radiation-sensitive onium cation.) (In formula (ia), R １ This is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or the aliphatic ring of a substituted or unsubstituted divalent alicyclic hydrocarbon group contains -O-, -CO-, and -SO3. ２ - A divalent group containing one or more groups selected from the group consisting of -. ２ This is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or an aliphatic ring of a substituted or unsubstituted monovalent alicyclic hydrocarbon group containing -O-, -CO-, and -SO3. ２ - A monovalent group containing one or more groups selected from the group consisting of -. ２ If R has substituents, ２ The substituents on are at least one selected from the group consisting of halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, and nitro groups. １ These are single bonds, -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ２ -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ３ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n is an integer from 0 to 3. If n is 0, R ２ It has 2 or more carbon atoms. When n is 2 or more, multiple R １ They are the same or different, multiple X ２ These are either the same or different. * indicates a combination.

7. A compound represented by the following formula (1A). (In formula (1A), R Ａ is a halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). Ｂ -CN, hydrogen atom, halogen atom, -NO ２ It is a group represented by -OH, -SH, -COOH, or the following formula (ia). However, R Ｂ In the case of -CN, R Ａ is a halogen atom, -OH, -SH or -COOH, or a group represented by the following formula (ia) (wherein -COOC ２ H ５ and -COO(CH ２ ) ２ (Excluding OH.) Z ＋ (This is a radiation-sensitive onium cation.) (In formula (ia), R １ This is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms, or the aliphatic ring of a substituted or unsubstituted divalent alicyclic hydrocarbon group contains -O-, -CO-, and -SO3. ２ - A divalent group containing one or more groups selected from the group consisting of -. ２ This is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, or an aliphatic ring of a substituted or unsubstituted monovalent alicyclic hydrocarbon group containing -O-, -CO-, and -SO3. ２ - A monovalent group containing one or more groups selected from the group consisting of -. ２ If R has substituents, ２ The substituents on are at least one selected from the group consisting of halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, and nitro groups. １ These are single bonds, -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ２ -CO-, -O-, -NR ３ -, -SO ２ - or -S-, or -CO-, -O-, -NR ３ -, -SO ２ A divalent linking group consisting of two or more elements selected from the group consisting of - and -S-. ３ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n is an integer from 0 to 3. If n is 0, R ２ It has 2 or more carbon atoms. When n is 2 or more, multiple R １ They are the same or different, multiple X ２ These are either the same or different. * indicates a combination.

Images