Radiation-sensitive composition and resist pattern forming method

Abstract

A radio-sensitive composition contains: a polymer (F) containing a structural unit having a fluorine atom and an alkali dissociable group; and a compound represented by formula (1). In formula (1), R 11 , R 12 , and R 13 are each independently a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms.

Description

Technical Field

[0001] [Cross-reference to related applications]

[0002] This application claims priority based on Japanese Patent Application No. 2024-50039, filed on March 26, 2024, which is incorporated herein by reference in its entirety.

[0003] This disclosure relates to a radiosensitive linear composition and a method for forming a resist pattern. Background Technology

[0004] In the photolithography technology used in the manufacturing process of various electronic components such as semiconductor devices and liquid crystal devices, acid is generated in the exposed part by irradiating the photosensitive linear composite with far-ultraviolet light (such as ArF excimer laser), extreme ultraviolet light (EUV), electron beam, etc. Through the chemical reaction involving the acid, the dissolution rate of the exposed part and the unexposed part relative to the developer is different, thereby forming a resist pattern on the substrate.

[0005] With the miniaturization of various electronic component structures, there is a demand for further miniaturization of resist patterns in photolithography processes. Furthermore, with the requirement for further miniaturization of resist patterns, various studies have been conducted to improve the resolution of the radiosensitive linear resin composition used in micro-processing using photolithography, or the shape of the resist pattern (for example, see Patent Document 1). Patent Document 1 discloses a radiosensitive linear resin composition comprising: a first polymer having structural units containing phenolic hydroxyl groups and structural units containing acid-dissociating groups; a second polymer having structural units containing at least one of fluorine atoms and silicon atoms and containing base-dissociating groups; a specific first compound that, upon irradiation with radiation, generates an acid that dissociates the acid-dissociating groups of the first polymer; and a specific second compound that, upon irradiation with radiation, generates an acid that substantially prevents the acid-dissociating groups of the first polymer from dissociating.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2018 / 230334 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In recent years, for example, attempts have been made to form fine patterns with linewidths below 40 nm. Furthermore, with the development of resist pattern miniaturization, further improvements in various properties are expected. Among these, suppressing defect formation during resist pattern formation becomes more important as resist patterns become finer.

[0011] When the properties (sensitivity, etc.) of a radiosensitive linear composition change over time, these changes may affect the shape of the resist pattern or cause defects. In particular, in recent years, with the further miniaturization of resist patterns or the increasing sensitivity of radiosensitive linear compositions, there is a demand for the stabilization of the properties of the radiosensitive linear compositions used in resist pattern formation.

[0012] This disclosure is made in view of the aforementioned issues, and its main objective is to provide a radiosensitive linear composition that can suppress the generation of defects during the formation of resist patterns and has excellent preservation stability, and a method for forming resist patterns using the radiosensitive linear composition.

[0013] Technical means to solve the problem

[0014] According to this disclosure, in one embodiment, a radiosensitive linear composition is provided, comprising: a polymer (F) containing structural units having fluorine atoms and base dissociation groups; and a compound represented by the following formula (1).

[0015] [Chemistry 1]

[0016]

[0017] (In equation (1), R) 11 R 12 and R 13 (Each group is a monovalent aliphatic hydrocarbon group with 1 to 20 carbon atoms)

[0018] According to this disclosure, in another embodiment, a method for forming a resist pattern is provided, comprising: a step of forming a resist film on a substrate using the radiosensitive linear composition; a step of exposing the resist film; and a step of developing the exposed resist film.

[0019] The effects of the invention

[0020] This disclosure provides a radiosensitive linear composition that can suppress the generation of defects during the formation of resist patterns and exhibits excellent preservation stability. Furthermore, the resist patterning method of this disclosure, by using the radiosensitive linear composition of this disclosure, can suppress the generation of defects. Detailed Implementation

[0021] The following provides a detailed description of matters related to the implementation method. Furthermore, in this specification, the numerical range indicated by “~” means the values ​​before and after the “~” are considered as a lower limit and an upper limit.

[0022] In this specification, the term "hydrocarbon group" encompasses chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Chain hydrocarbon group" refers to straight-chain hydrocarbon groups and branched hydrocarbon groups that contain only chain structures and no cyclic structures. Chain hydrocarbon groups can be saturated or unsaturated. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as its ring structure and does not contain an aromatic ring structure. Alicyclic hydrocarbon groups do not necessarily need to contain only an alicyclic hydrocarbon structure; they may also include groups with chain structures in a portion thereof. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as its ring structure. Aromatic hydrocarbon groups do not necessarily need to contain only an aromatic ring structure; they may also include chain structures or alicyclic hydrocarbon structures in a portion thereof. "Organic group" refers to a group of atoms formed by removing any hydrogen atoms from a carbon-containing compound (i.e., an organic compound). "Aromatic ring" encompasses aromatic hydrocarbon rings and aromatic heterocycles.

[0023] The "main chain" of a polymer refers to the "stem" portion of the polymer containing the longest atomic chain. The "stem" portion may contain ring structures. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the polymer's main chain. A "side chain" refers to a portion that branches off from the polymer's "stem." A "structural unit" refers to a unit that primarily constitutes the main chain structure and contains at least two units within the main chain structure. A typical structural unit is a monomer unit. The term "structural unit" also includes those formed by reacting a monomer unit with a reactive group with a compound having a functional group capable of reacting with the reactive group, and those formed by polymerizing a monomer protected by a protecting group such as a base-dissociating group, followed by hydrolysis to remove the protection. "(meth)acrylate" is a term encompassing both "acrylate" and "methacrylate."

[0024] The expression "substituted or unsubstituted p-valent hydrocarbon group (where p is an integer greater than or equal to 1)" includes p-valent hydrocarbon groups (i.e., unsubstituted p-valent hydrocarbon groups) and groups formed by removing p hydrogen atoms from the hydrocarbon structural portion of a substituted hydrocarbon group. If we cite an example of substituted or unsubstituted p-valent hydrocarbon groups, for example, alkyl or fluoroalkyl groups correspond to the case of p=1, and alkyldiyl or fluoroalkyldiyl groups correspond to the case of p=2. Among these, fluoroalkyl groups correspond to "substituted monovalent hydrocarbon groups," and fluoroalkyldiyl groups correspond to "substituted divalent hydrocarbon groups." The same applies to other groups labeled "substituted or unsubstituted."

[0025] Radioactive linear compositions

[0026] The radiosensitive linear composition disclosed herein (hereinafter also referred to as "the composition") comprises: a polymer (F) containing a structural unit having a fluorine atom and a base dissociation group; and a compound represented by the following formula (1) (hereinafter also referred to as "compound (S)").

[0027] [Chemistry 2]

[0028]

[0029] (In equation (1), R) 11 R 12 and R 13 (Each group is a monovalent aliphatic hydrocarbon group with 1 to 20 carbon atoms)

[0030] This composition, comprising a polymer (F) and a compound (S), provides a radiosensitive linear composition that suppresses the formation of development defects during resist pattern formation and exhibits excellent storage stability. The reasons for this effect are uncertain, but the following can be considered: It is believed that by including the polymer (F) in the radiosensitive linear composition, during resist pattern formation, the base-dissociating groups dissociate upon contact with the developer, increasing the polarity of the polymer (F). This increases the hydrophilicity of the resist film surface, thereby improving the performance in suppressing defect formation (hereinafter also referred to as "defect suppression"). On the other hand, regarding the base-dissociating groups in the polymer (F), when electron-withdrawing groups such as fluorine atoms are located near the base-dissociating groups, reactivity increases, for example, making it easier to react with solvent components in the composition. Therefore, it is believed that the properties of the radiosensitive linear composition containing the polymer (F) are prone to change over time, and these changes can easily affect the shape of the resist pattern or the formation of defects. In this respect, compound (S) has relatively low nucleophilicity, thus exhibiting a low probability of reaction with polymer (F). Furthermore, it displays high solubility relative to polymer components containing polymer (F) or radiosensitive linear acid generators. Therefore, the components contained in the radiosensitive linear composition can be kept in a stable state. As a result, it is believed that this composition, containing both polymer (F) and compound (S), can achieve both defect suppression and storage stability. The reasons given are always speculative and do not limit the scope of the invention in any way.

[0031] The following provides a detailed description of the components contained in this composition and any other components that may be formulated. Furthermore, unless otherwise specified, each component contained in this composition may be used alone or in combination of two or more.

[0032] <Polymer (F)>

[0033] The polymer (F) comprises structural units having fluorine atoms and base-dissociable groups (hereinafter also referred to as "structural units (i)"). Here, in this specification, a "base-dissociable group" refers to a group that substitutes for the hydrogen atom of an acid group such as a carboxyl or hydroxyl group, and is a group that decomposes in a 2.38% by mass aqueous solution of tetramethyl ammonium hydroxide (TMAH) at 23°C for 1 minute.

[0034] The fluorine atom content (hereinafter also referred to as "fluorine atom content") of the polymer (F) is preferably 1% by mass or more, more preferably 4% by mass or more, and even more preferably 7% by mass or more. Furthermore, the fluorine atom content of the polymer (F) is preferably 60% by mass or less, more preferably 40% by mass or less. In addition, the fluorine atom content (by mass%) of the polymer can be determined by... 13 C-NMR ( 13 C-Nuclear Magnetic Resonance, 13 The structure of the polymer is determined by methods such as C-NMR spectroscopy, and calculations are performed based on the determined structure.

[0035] The number of fluorine atoms in a structural unit (i) is only one or more. From the viewpoint of sufficiently suppressing the generation of defects during resist pattern formation, the number of fluorine atoms in the structural unit (i) is preferably two to ten. Furthermore, from the viewpoint of balancing the defect suppression and storage stability of the composition to a high level, the number of fluorine atoms in the structural unit (i) is more preferably two to six, and even more preferably two to four.

[0036] Polymer (F) may also include only structural unit (i). Alternatively, polymer (F) may include structural units different from structural unit (i) in addition to structural unit (i). Structural units different from structural unit (i) may include one or more of the following: structural units having an acid-dissociable group (designated as "structural unit (ii)"); and structural units having a monovalent fluorinated aliphatic hydrocarbon group (designated as "structural unit (iii)"). Each structural unit will be described in detail below.

[0037] (Structural Unit (i))

[0038] The structural unit (i) is not particularly limited as long as it has a base dissociative group. As a preferred example of the structural unit (i), the structural unit represented by the following formula (2) can be listed.

[0039] [Chemistry 3]

[0040]

[0041] (In equation (2), R) F It can be a hydrogen atom, a fluorine group, a methyl group, a trifluoromethyl group, or a methoxymethyl group. A 1 It can be a single bond, -O-, -CO-, -COO-, -NH-, or -CONH-. R 21 It is a hydrocarbon group with a valence of (s+1) having 1 to 20 carbon atoms, or it is an R group of the hydrocarbon group. 22 The terminal bonds on the side contain oxygen atoms, sulfur atoms, and -NR. 24 - A group consisting of a carbonyl group, a sulfonyl group, a -CO-O- group, or a -CO-NH- group, or a group with a heterocyclic structure and a (s+1) valence of 3 to 20 carbon atoms. R 24 It can be a hydrogen atom or a monovalent organic group. R 22 It is a single bond or a divalent fluorinated chain hydrocarbon group with 1 to 20 carbon atoms. X 1 For oxygen atoms, -CO-O- or -SO2-O- 。 "Indicates to R" 23 The bond structure. R 23 It is a monovalent organogroup with 1 to 30 carbon atoms. Among them, in X... 1 -CO-O- or -SO2-O- In the case of R 22 and R 23 At least one of them is relative to X 1 A group consisting of a bonded carbon atom or a carbon atom adjacent to the said carbon atom and bonded with a fluorine atom, or R 23 To have with X 1 A bonded aromatic ring and a fluorine atom or a trifluoromethyl group bonded to the aromatic ring. Wherein, in R 23 In, relative to X 1 The bonding position of the fluorine atom or trifluoromethyl group relative to X 1 The bonding position of the aromatic ring in the bond is either 2 or 3 positions. In X 1 In the case of oxygen atoms, R 22 For a single bond, R 21 R is a hydrocarbon group with a carbon number of 1 to 20 and a valence of (s+1). 23 For X 1 The group has a carbonyl group bonded to its end on one side, and a fluorine atom bonded to the carbon atom adjacent to the carbonyl group. s is an integer from 1 to 3. Where s is 2 or 3, multiple R... 22 Same or different, multiple X 1 Same or different, multiple R 23 (Same or different)

[0042] In equation (2), R FIt can be a hydrogen atom, a fluorine group, a methyl group, a trifluoromethyl group, or a methoxymethyl group. Of these, from the viewpoint of providing the copolymerizability of the monomer that provides structural unit (i), a hydrogen atom or a methyl group is preferred. From the viewpoint of providing the copolymerizability of the monomer that provides structural unit (i), A 1 Preferably, it is a single bond or -COO-, more preferably -COO-.

[0043] As R 21 The hydrocarbon groups with a valence of (s+1) of 1 to 20 carbon atoms can be listed as follows: chain hydrocarbon groups with a valence of (s+1) of 1 to 20 carbon atoms, alicyclic hydrocarbon groups with a valence of (s+1) of 3 to 20 carbon atoms, and aromatic hydrocarbon groups with a valence of (s+1) of 6 to 20 carbon atoms.

[0044] As a chain hydrocarbon group with a (s+1) valence having 1 to 20 carbon atoms, examples can be listed that are formed by removing s (where s is an integer from 1 to 3) hydrogen atoms from a monovalent chain hydrocarbon group having 1 to 20 carbon atoms. Specific examples of monovalent chain hydrocarbon groups include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl; alkenyl groups such as vinyl, propynyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl. 21 The chain hydrocarbon group with (s+1) valence representing 1 to 20 carbon atoms is preferably a saturated chain hydrocarbon group among these, and more preferably a saturated chain hydrocarbon group with 1 to 4 carbon atoms.

[0045] As a (s+1) valent alicyclic hydrocarbon group with 3 to 20 carbon atoms, examples include groups formed by removing s hydrogen atoms from a monovalent alicyclic hydrocarbon group with 3 to 20 carbon atoms. Specific examples of monovalent alicyclic hydrocarbon groups include: monovalent monocyclic alicyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, methylcyclopentyl, ethylcyclopentyl, methylcyclohexyl, and ethylcyclohexyl; monovalent monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl, cyclohexenyl, methylcyclopentenyl, and methylcyclohexenyl; monovalent polycyclic alicyclic saturated hydrocarbon groups such as norbornyl, adamantyl, and tricyclodecyl; and monovalent polycyclic alicyclic unsaturated hydrocarbon groups such as norbornyl, tricyclodecenyl, and dihydroindenyl.

[0046] As aromatic hydrocarbon groups with a (s+1) valence having 6 to 20 carbon atoms, examples include groups formed by removing s hydrogen atoms from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. Specific examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include: phenyl, tolyl, xylyl, mesitylelel, naphthyl, methylnaphthyl, anthracenel, methylanthrayl, indenyl, and other aryl groups; benzyl, phenethyl, naphthylmethyl, anthracenemethyl, and other aralkyl groups, etc.

[0047] In R 21Among the (s+1) valence groups with 3 to 20 carbon atoms representing heterocyclic structures, examples of heterocyclic structures include aliphatic heterocyclic structures with 3 to 20 carbon atoms and aromatic heterocyclic structures with 4 to 20 carbon atoms. Specific examples of aliphatic heterocyclic structures with 3 to 20 carbon atoms include cyclic ether structures, lactone structures, cyclic carbonate structures, sulfonyl lactone structures, and thiane structures. The aliphatic heterocyclic structure can be any of a monocyclic or polycyclic structure, and can also be any of a bridged ring structure, a condensed ring structure, or a spirocyclic structure. Furthermore, R... 21 The aliphatic heterocyclic structures representing 3-20 carbon atoms can be combinations of two or more of the following: bridged ring structures, condensed ring structures, and spirocyclic structures. Examples of aromatic heterocyclic structures with 4-20 carbon atoms include: furan ring structures, benzofuran ring structures, thiophene structures, benzothiophene ring structures, pyridine ring structures, quinoline ring structures, and isoquinoline ring structures. In R... 21 In the case of a heterocyclic group with 3 to 20 carbon atoms and a (s+1) valence, R 21 Preferably, it is a group with an aliphatic heterocyclic structure having 3 to 20 carbon atoms.

[0048] As R 24 Examples of monovalent organic groups include: monovalent chain hydrocarbon groups with 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups with 3 to 10 carbon atoms, and monovalent aromatic hydrocarbon groups with 6 to 12 carbon atoms. R 24 Preferably, it is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group; more preferably, it is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0049] In R 22 In the case of a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms, examples of such fluorinated chain hydrocarbon groups include those in which one or more hydrogen atoms are substituted with fluorine atoms. The divalent chain hydrocarbon group having 1 to 20 carbon atoms can be linear or branched, and can be saturated or unsaturated. Specific examples of these include those from R... 21 The radical is formed by removing one hydrogen atom from a monovalent chain hydrocarbon group with 1 to 20 carbon atoms as shown in the description. R 22 The divalent fluorinated chain hydrocarbon group representing 1 to 20 carbon atoms is preferably a straight-chain or branched fluoroalkyl group, more preferably a straight-chain or branched fluoroalkyl group representing 1 to 4 carbon atoms.

[0050] As R 23The monovalent organic groups representing 1 to 30 carbon atoms can be exemplified by: monovalent chain hydrocarbon groups with 1 to 30 carbon atoms, monovalent fluorinated chain hydrocarbon groups with 1 to 30 carbon atoms, monovalent alicyclic hydrocarbon groups with 3 to 30 carbon atoms, monovalent fluorinated alicyclic hydrocarbon groups with 3 to 30 carbon atoms, monovalent aromatic hydrocarbon groups with 6 to 30 carbon atoms, monovalent fluorinated aromatic hydrocarbon groups with 6 to 30 carbon atoms, and any methylene group or monovalent fluorinated hydrocarbon group with 1 to 30 carbon atoms substituted with a heteroatom-containing group such as -O-, -CO-, -COO-, -NH-, or -CONH-. Additionally, R... 23 It can be a base containing a chain structure or a base having a ring structure.

[0051] In equation (2), X 1 -CO-O- or -SO2-O- Under the following condition (I), in X 1 In the case of oxygen atoms, the following condition (II) is satisfied.

[0052] Condition (I): R 22 and R 23 At least one of them is in relation to X 1 A group consisting of a bonded carbon atom or a carbon atom adjacent to the said carbon atom bonded with a fluorine atom, or R 23 To have with X 1 A bonded aromatic ring and a fluorine atom or a trifluoromethyl group bonded to the aromatic ring. Wherein, in R 23 To have with X 1 In the case of a bonded aromatic ring and a fluorine atom or a trifluoromethyl group bonded to said aromatic ring, relative to X 1 The bonding position of the fluorine atom or trifluoromethyl group relative to X 1 The bonding position of the aromatic ring in the bond is 2 or 3 positions.

[0053] Condition (II): R 22 For a single bond, R 21 R is a hydrocarbon group with 1 to 20 carbon atoms. 23 For X 1 The end of the side is bonded with a carbonyl group, and a fluorine atom is bonded to the carbon atom adjacent to the carbonyl group.

[0054] In condition (I), in R 22 and R 23 At least one of them is in relation to X 1 The bonded carbon atoms (also referred to as "carbon atom Y") 1 ) or with carbon atom Y 1 Adjacent carbon atoms (also referred to as "carbon atom Y") 2In the case where a fluorine atom is bonded to a group, it interacts with a carbon atom Y. 1 Or carbon atom Y 2 The number of fluorine atoms in the bond is not particularly limited; it can be one or more. Carbon atom Y 1 and carbon atom Y 2 Preferably, the carbon atom constituting a hydrocarbon group having one or more carbon atoms is used; more preferably, the carbon atom constituting a saturated chain hydrocarbon group having one or more carbon atoms is used. Furthermore, in terms of improving defect suppression performance when condition (I) is satisfied, R... 22 and R 23 Preferably, they are saturated chain hydrocarbon groups or fluorinated saturated chain hydrocarbon groups that are independently formed, and R 22 and R 23 At least one of them has a fluorine atom.

[0055] Under the condition (I), R 23 It can be used to have X 1 A bonded aromatic ring and a fluorine atom or a trifluoromethyl group bonded to the aromatic ring. In this case, the X in the aromatic ring... 1 When the bonding position is set to position 1, the fluorine atom or trifluoromethyl group bonds to the 2nd or 3rd position of the aromatic ring. As this type of R... 23 Specific examples include: o-fluorophenyl, o-trifluoromethylphenyl, m-fluorophenyl, m-trifluoromethylphenyl, etc.

[0056] In condition (II), in R 23 For X 1 The end of the side is bonded with a carbonyl group, and the carbon atom adjacent to the carbonyl group (also referred to as "carbon atom Y") 3 In the case of a group with a fluorine atom bonded to it, it bonds with a carbon atom Y. 3 The number of fluorine atoms in the bond is not particularly limited; it can be one or more. Carbon atom Y 3 Preferably, the carbon atoms constituting a hydrocarbon group having 1 or more carbon atoms are carbon atoms constituting a saturated chain hydrocarbon group having 1 or more carbon atoms.

[0057] s is an integer from 1 to 3, preferably 1 or 2.

[0058] Structural unit (i) is preferably generated by the removal of a base dissociative group to produce a carboxyl or hydroxyl group. Specific examples of preferred structural unit (i) include the structural unit represented by formula (2A) and the structural unit represented by formula (2B) below.

[0059] [Chemistry 4]

[0060]

[0061] (In equations (2A) and (2B), R)f1 R f2 and R f3 Each can be independently a single bond, methylene, monofluoromethylene, or perfluoromethylene. Among them, R... f1 and R f2 At least one of them has a fluorine atom. R 22a It is a single bond or a divalent fluorinated chain hydrocarbon group having 1 to 12 carbon atoms. R 21a R is a hydrocarbon group with a valence of (s+1) and a carbon number of 1 to 20. 23a and R 23b It is a hydrogen atom, a fluorine atom, or a monovalent organic group having 1 to 20 carbon atoms. R F A 1 R 21 and s and R in equation (1) F A 1 R 21 (and 's' have the same meaning)

[0062] In terms of achieving a higher level of balance between the preservation stability and defect suppression of the composition, structural unit (i) preferably satisfies the condition (I), and more preferably is the structural unit represented by formula (2A). Furthermore, in terms of even better defect suppression, R in formula (2A) is preferred. 22a It is an alkyldiyl or fluoroalkyldiyl, R 23a It can be a hydrogen atom, an alkyl group, or a fluoroalkyl group. R 23a More preferably, it is an alkyl or fluoroalkyl group.

[0063] The number of fluorine atoms in formulas (2A) and (2B) is preferably two to ten, more preferably two to six, and even more preferably two to four.

[0064] As specific examples of structural unit (i), the structural units represented by the following formulas can be listed. However, structural unit (i) is not limited to these specific examples.

[0065] [Chemistry 5]

[0066]

[0067] [Chemistry 6]

[0068]

[0069] (where R) F (can be hydrogen atom, fluorine group, methyl, trifluoromethyl or methoxymethyl)

[0070] In the polymer (F), the content of structural unit (i) relative to the total amount of structural units in the polymer (F) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more. Furthermore, the content of structural unit (i) relative to the total amount of structural units in the polymer (F) is preferably 90 mol% or less, more preferably 85 mol% or less. By setting the content of structural unit (i) within the aforementioned range, the generation of defects can be sufficiently suppressed during resist pattern formation.

[0071] (Structural Unit (ii))

[0072] Structural unit (ii) is a structural unit having an acid-dissociable group. Structural unit (ii) can be introduced into polymer (F) for example to increase the difference in solubility of polymer (F) in the exposed and unexposed portions. Here, in this specification, "acid-dissociable group" refers to a group that substitutes for the hydrogen atom of an acid group such as a carboxyl or hydroxyl group, and is a group that is detached due to the action of an acid.

[0073] Structural unit (ii) is not particularly limited as long as it has an acid-dissociable group. Examples of structural units (ii) include: the structural unit represented by the following formula (4-1) (hereinafter also called "structural unit (iia)"), the structural unit represented by the following formula (4-2) (hereinafter also called "structural unit (iib)"), and the structural unit represented by the following formula (4-3) (hereinafter also called "structural unit (iic)").

[0074] [Chemistry 7]

[0075]

[0076] (In equation (4-1), R) 30 It can be a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L 2 It is a divalent chain-like organic group or an alicyclic hydrocarbon group. R 31 It is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. R 32 and R 33 Independently, they are substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, or monovalent aromatic heterocyclic groups, or represent R. 32 and R 33 Combine with R 32 and R 33 The bonded carbon atoms together form an alicyclic hydrocarbon structure with 3 to 20 carbon atoms. Among them, in R... 31 In the case of hydrogen atoms, R 32 and R 33Any one or both of them are independently substituted or unsubstituted monovalent alicyclic unsaturated hydrocarbon groups, or substituted or unsubstituted monovalent aromatic hydrocarbon groups, or monovalent aromatic heterocyclic groups, or represent R 32 and R 33 Combine with R 32 and R 33 The bonded carbon atoms together form an alicyclic unsaturated hydrocarbon structure with 3 to 20 carbon atoms. g1 is 0 or 1.

[0077] In equation (4-2), R 30 It can be a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L 3 For single bonds, -O-, -CO-, -COO- or -CONH-. "" indicates a bond with the main chain. R 34 R 35 and R 36 Each of the following is independently a hydrogen atom and 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. R 28 To be with -OC(R 34 (R) 35 (R) 36 Different monovalent substituents. g2 is an integer from 0 to 4.

[0078] In equation (4-3), R 30 It can be a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L 4 For single bonds, -O-, -CO-, -COO- or -CONH-. "" indicates a bond with the main chain. R 37 It 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. R 38 and R 39 Independently comprising 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 representing R 38 and R 39 Combine with R 38 and R 39 The bonded carbon atoms together form an alicyclic hydrocarbon structure with 3 to 20 carbon atoms. R 29 To be compatible with -COO-C(R) 37 (R) 38 (R) 39 Different monovalent substituents. g3 is an integer from 0 to 4.

[0079] In equation (4-1), from the viewpoint of the copolymerization of the monomers providing the structural unit (iia), R 30 Preferably, it is a hydrogen atom or a methyl group, more preferably a methyl group. In the above formula (4-2), from the viewpoint of the copolymerization of the monomer that provides the structural unit (iib), R 30 Preferably, it is a hydrogen atom. Similarly, R in formula (4-3) 30 Preferably, it is a hydrogen atom or a methyl group. The L in formula (4-2) 3 and L in equation (4-3) 4 Preferably, they are single bonds, -COO-, or -CONH-, respectively.

[0080] L in equation (4-1) 2 Examples of divalent chain-like organic groups include straight-chain or branched saturated hydrocarbon groups with 1 to 20 carbon atoms, and divalent groups with 2 to 20 carbon atoms in which the methylene group contained in a chain-like or branched saturated hydrocarbon group is substituted by a heteroatom-containing group (e.g., -O-, -S-, -CO-, -COO-, -NH-, -NHCO-, -SO2-). As L 2 Specific and preferred examples of the divalent alicyclic hydrocarbon group represented can be cited from R in the formula (2). 22 The group represented by the monovalent alicyclic hydrocarbon group is further formed by removing one hydrogen atom. L 2 Preferably, it is a chain-like organic group.

[0081] R in equations (4-1) to (4-3) 31 ~R 33 R 34 ~R 36 Or R 37 ~R 39 The monovalent hydrocarbon groups representing 1 to 20 carbon atoms can be exemplified as: monovalent chain hydrocarbon groups with 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups with 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups with 6 to 20 carbon atoms. Specific examples of these groups include those corresponding to R in formula (2). 22 The same group as the monovalent hydrocarbon group illustrated in the description.

[0082] As R 32 and R 33 Combine with R 32 and R 33 The bonded carbon atoms together form an alicyclic hydrocarbon structure with 3 to 20 carbon atoms, and R 35 and R 36 Combine with R 35 and R 36Alicyclic hydrocarbon structures with 3 to 20 carbon atoms formed by the bonded carbon atoms include: monocyclic saturated alicyclic hydrocarbon structures such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; monocyclic unsaturated alicyclic hydrocarbon structures such as cyclopentene and cyclohexene; and polycyclic alicyclic hydrocarbon structures such as norbornene, adamantane, tricyclic decane, and tetracyclic dodecane.

[0083] As R 34 ~R 36 Or R 37 ~R 39 The monovalent oxyalkyl groups representing carbon numbers from 1 to 20 can be, for example, listed in the R... 31 ~R 33 R 34 ~R 36 and R 36 ~R 36 These include monovalent hydrocarbon groups with 1 to 20 carbon atoms whose bond ends contain oxygen atoms. Among these, R... 31 ~R 33 Or R 36 ~R 39 The monovalent oxyalkyl group represented is preferably alkoxy, cycloalkoxy, or cycloalkylalkoxy.

[0084] In R 31 ~R 33 R 34 ~R 36 Or R 37 ~R 39 When the indicated group has a substituent, examples of such substituents include: halogen atoms, hydroxyl groups, and alkoxy groups having 1 to 3 carbon atoms. Additionally, in R... 32 and R 33 Combine with R 32 and R 33 In the case where the bonded carbon atoms together form an alicyclic hydrocarbon structure with 3 to 20 carbon atoms, or R 38 and R 39 Combine with R 38 and R 39 When the bonded carbon atoms together form an alicyclic hydrocarbon structure with 3 to 20 carbon atoms, the exemplified substituents or alkyl groups may also be bonded to the ring.

[0085] As R 28 Or R 29 Examples of monovalent substituents include: alkyl groups with 1 to 3 carbon atoms, alkoxy groups with 1 to 3 carbon atoms, hydroxyl groups, and halogen atoms (such as fluorine, chlorine, bromine, and iodine atoms).

[0086] g2 and g3 are preferably 0 to 2 respectively.

[0087] As a specific example of structural unit (iia) in structural unit (ii), structural units represented by the following formulas can be listed. Furthermore, structural unit (ii) is not limited to the specific examples shown below. In the formula, R... 30 It can be a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0088] [Chemistry 8]

[0089]

[0090] [Chemistry 9]

[0091]

[0092] As specific examples of structural units (iib), structural units represented by the following formulas can be listed.

[0093] [Chemistry 10]

[0094]

[0095] As a specific example of a structural unit (iic), structural units represented by the following formulas can be listed.

[0096] [Chemistry 11]

[0097]

[0098] [Chemistry 12]

[0099]

[0100] When the polymer (F) contains structural unit (ii), the content of structural unit (ii) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to the total amount of structural units in the polymer (F). Furthermore, the content of structural unit (ii) is preferably 50 mol% or less, more preferably 40 mol% or less, relative to the total amount of structural units in the polymer (F). By setting the content of structural unit (ii) within the aforementioned range, the defect suppression properties of this composition can be improved.

[0101] (Structural Unit (iii))

[0102] Structural unit (iii) is a structural unit with a monovalent fluorinated aliphatic hydrocarbon group. By introducing structural unit (iii) into polymer (F), the fluorine atom content in polymer (F) can be easily adjusted.

[0103] As a specific example of structural unit (iii), the structural unit represented by the following equation (5) can be listed.

[0104] [Chemistry 13]

[0105]

[0106] (In equation (5), R) C It can be a hydrogen atom, a fluorine group, a methyl group, a trifluoromethyl group, or a methoxymethyl group. G can be a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2-O-NH-, -CONH-, or -O-CO-NH-. R E (A monovalent fluorinated chain hydrocarbon group with 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group with 3 to 20 carbon atoms)

[0107] In equation (5), from the viewpoint of providing the copolymerization of the monomers of structural unit (iii), R C Preferably, it contains hydrogen atoms and methyl groups, more preferably methyl groups. From the viewpoint of providing copolymerizability of the monomer that provides structural unit (iii), G is preferably a single bond or -COO-, more preferably -COO-.

[0108] As R E The monovalent fluorinated chain hydrocarbon group representing 1 to 20 carbon atoms can be exemplified by groups in which some or all of the hydrogen atoms of a straight-chain or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms. As R E The monovalent fluorinated alicyclic hydrocarbon groups representing 3 to 20 carbon atoms can be categorized as those where some or all of the hydrogen atoms in a monocyclic or polycyclic alicyclic hydrocarbon group with 3 to 20 carbon atoms are substituted with fluorine atoms. Among these, R... E Preferably, it is a monovalent fluorinated chain hydrocarbon group, and more preferably a monovalent fluorinated alkyl group.

[0109] As a specific example of structural unit (iii), structural units represented by the following formulas can be listed. Furthermore, structural unit (iii) is not limited to the specific examples shown below.

[0110] [Chemistry 14]

[0111]

[0112] When the polymer (F) has structural unit (iii), the content of structural unit (iii) is preferably 30 mol% or less, more preferably 20 mol% or less, relative to the total amount of structural units in the polymer (F). By setting the content of structural unit (iii) within the aforementioned range, the fluorine atom content of the polymer (F) can be adjusted more appropriately while ensuring defect suppression, further promoting the surface-biased presence of the resist film.

[0113] In addition to those listed above, structural units that may be present in the polymer (F) include, for example: structural units having an aromatic ring and a hydroxyl group bonded to the aromatic ring; structural units containing a non-acid-dissociable hydrocarbon group (specifically, structural units derived from styrene or fluorinated styrene, structural units derived from vinylnaphthalene, structural units derived from cyclopentyl methacrylate, structural units derived from cyclohexyl methacrylate, etc.); and structural units having a fluorine atom and a hydroxyl group (specifically, 3-hydroxy-3,3-di(trifluoromethyl)-propyl(meth)acrylate, etc.). The proportions of these structural units can be suitably set according to each structural unit without impairing the effects of the present invention.

[0114] The molecular weight distribution (Mw) of polymer (F) obtained by gel permeation chromatography (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) represented by the ratio of Mn to Mw obtained by GPC of polymer (F) is preferably 1 or more and 5 or less, more preferably 1 or more and 3 or less.

[0115] In this composition, the content of polymer (F) 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, relative to the total amount of solid components contained in the composition. Furthermore, the content of polymer (F) is preferably 15% by mass or less, more preferably 10% by mass or less, relative to the total amount of solid components contained in the composition. In addition, in this specification, "solid components" refers to components other than solvents contained in the composition.

[0116] Polymer (F) can be synthesized, for example, by polymerizing monomers providing the structural units in a suitable solvent using known free radical polymerization initiators. Examples of free radical polymerization initiators include azo-based free radical initiators (e.g., azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), etc.) and peroxide-based free radical initiators (e.g., benzoyl peroxide, etc.). Examples of solvents used in the polymerization include straight-chain alkanes, cycloalkanes, aromatic hydrocarbons, halogenated hydrocarbons, saturated carboxylic acid esters, ketones, ethers, and alcohols. The reaction temperature in the polymerization is preferably 40°C to 150°C, more preferably 50°C to 120°C. The reaction time is preferably 1 hour to 48 hours, more preferably 2 hours to 24 hours.

[0117] <Compound (S)>

[0118] The compound (S) is represented by the following formula (1). The compound (S) is preferably incorporated into the composition as a solvent.

[0119] [Chemistry 15]

[0120]

[0121] (In equation (1), R) 11 R 12 and R 13 (Each group is a monovalent aliphatic hydrocarbon group with 1 to 20 carbon atoms)

[0122] In the above equation (1), R is... 11 R 12 Or R 13 The monovalent aliphatic hydrocarbon groups representing 1 to 20 carbon atoms can be exemplified by monovalent chain hydrocarbon groups with 1 to 20 carbon atoms and monovalent alicyclic hydrocarbon groups with 3 to 20 carbon atoms. Specific examples of these include R in formula (2). 21 The bases represented are the same bases shown in the description.

[0123] From the viewpoint of the reactivity of the polymer components (F) contained in this composition with alkali and the ease of obtaining the compound (S), R 11 R 12 Or R 13 Preferably, it is a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms.

[0124] In the above, R 11 and R 12 Preferably, it is an alkyl group having 1 to 3 carbon atoms, more preferably methyl or ethyl. 13 Preferably, it is an alkyl group having 1 to 4 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.

[0125] Specific examples of compounds (S) include: methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, isopropyl 2-hydroxyisobutyrate, tert-butyl 2-hydroxyisobutyrate, methyl 2-hydroxy-2-methylbutyrate, ethyl 2-hydroxy-2-methylbutyrate, isopropyl 2-hydroxy-2-methylbutyrate, etc.

[0126] The content of compound (S) in this composition is preferably 10% by mass or more relative to the total amount of solvent contained in the composition. By setting the content of compound (S) within the aforementioned range, the storage stability of this composition can be improved. In terms of further enhancing the storage stability of this composition, the content of compound (S) is more preferably 15% by mass or more relative to the total amount of solvent contained in the composition, more preferably 20% by mass or more, more preferably 25% by mass or more, and particularly preferably 30% by mass or more.

[0127] <Other Ingredients>

[0128] This composition may also contain components different from polymer (F) and compound (S) (hereinafter also referred to as "other components"). Examples of other components include: a polymer containing a structural unit having an aromatic ring and a hydroxyl group bonded to said aromatic ring (hereinafter also referred to as "polymer (A)"), a solvent different from compound (S) (hereinafter also referred to as "other solvents"), a radiosensitive linear acid generator, etc.

[0129] <Polymer (A)>

[0130] Polymer (A) comprises a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring (designated as the "first structural unit"). Polymer (A) is a different polymer from polymer (F). In a preferred form of this composition, polymer (A) is the base resin, and polymer (F) is a polymer with a higher fluorine content than polymer (A) (also referred to as a "high-fluorine polymer"). When a photoresist film is formed from a radiosensitive linear composition containing polymer (A) and polymer (F), polymer (F) tends to be more likely to be present on the surface of the photoresist film than polymer (A).

[0131] Here, in this specification, "base resin" refers to the main component of the polymer composition contained in the radiosensitive linear composition. Specifically, in one form of the composition containing polymer (A) as a base resin and polymer (F) as an additive, the content of polymer (A) is greater than that of polymer (F). In this case, the content of polymer (A) is more than 50% by mass, preferably 70% by mass or more, and more preferably 85% by mass or more, relative to the total amount of polymer (A) and polymer (F) contained in the composition. When polymer (F) is formulated into the radiosensitive linear composition as an additive, polymer (F) is formulated into the composition, for example, as a water-repellent additive, as a surface modifier to adjust the hydrophilicity / hydrophobicity of the resist film surface, or as a modifier to further improve photolithography performance.

[0132] Furthermore, polymer (A) is a polymer that contains a structural unit (first structural unit) having an aromatic ring and a hydroxyl group bonded to the aromatic ring, and is different from polymer (F). Here, "polymer (A) is a polymer different from polymer (F)" does not mean that polymer (F) does not contain a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring. That is, polymer (F) may also contain structural units having an aromatic ring and a hydroxyl group bonded to the aromatic ring in addition to structural unit (i). When polymer (F) contains a structural unit having an aromatic ring and a hydroxyl group bonded to the aromatic ring, the proportion of the structural unit relative to the total amount of structural units in polymer (F) is, for example, 30 mol% or less, or possibly 20 mol% or less.

[0133] Polymer (A) may also include, in addition to the first structural unit, one or more of the following: a structural unit having an acid-dissociable group (designated as the "second structural unit"); a structural unit having an onium salt structure formed by a radiosensitive linear onium cation and an organic anion (designated as the "third structural unit"); a structural unit having a lactone structure, a cyclic carbonate structure, or a sulfonolactone structure, or a cyclic structure formed by a combination of two or more of these (designated as the "fourth structural unit"); and a structural unit having an alcoholic hydroxyl group (designated as the "fifth structural unit"). Each structural unit will be described in detail below.

[0134] (First structural unit)

[0135] The presence of hydroxyl groups bonded to aromatic rings in polymer (A) further enhances the line width roughness (LWR) and critical dimension uniformity (CDU) properties of the composition, significantly reduces the leaching of unexposed areas into the developer, and further minimizes development defects; these aspects are preferred. Furthermore, polymer (A) with hydroxyl groups bonded to aromatic rings is preferably used, particularly in pattern formation using radiation with wavelengths below 50 nm, such as electron beams or EUV. Moreover, the first structural unit differs from the second structural unit in that it lacks an acid-dissociating group, and differs from the third structural unit in that it lacks an onium salt structure. That is, in this specification, structural units having both hydroxyl groups bonded to aromatic rings and acid-dissociating groups are classified as second structural units, and structural units having both hydroxyl groups bonded to aromatic rings and onium salt structures are classified as third structural units.

[0136] As a specific example of the first structural unit, the structural unit represented by the following formula (3) can be listed.

[0137] [Chemistry 16]

[0138]

[0139] In equation (3), R 50 It can be a hydrogen atom, a fluorine group, a methyl group, or a trifluoromethyl group. L 1 It can be a single bond, -COO-, or -CONH-. A 2 It is an aromatic ring group. R 4 This refers to a substituent that is different from the hydroxyl group. n1 is an integer greater than or equal to 1. n2 is an integer greater than or equal to 0. When n2 is greater than or equal to 2, multiple R groups... 4 (Same or different)

[0140] In equation (3), from the viewpoint of the copolymerization of the monomers providing the first structural unit, R 50 Preferably, it contains hydrogen atoms or methyl groups.

[0141] A 2 This is a group formed by removing (n1+n2+1) hydrogen atoms from the ring portion of an aromatic ring. The aromatic ring is preferably an aromatic hydrocarbon ring, such as benzene rings, naphthalene rings, anthracene rings, phenanthrene rings, etc. From the viewpoint of ease or sensitivity of synthesis of the monomer providing the first structural unit, A... 2 The aromatic ring is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring. The position of the hydroxyl group bonded to the aromatic ring is not particularly limited. For example, when the first structural unit has a hydroxyl group bonded to the benzene ring, the bond position of the hydroxyl group in the benzene ring of the first structural unit can be any of the ortho, meta, and para positions relative to the other groups.

[0142] R 4 Any group that is different from the hydroxyl group is acceptable. As R 4 Specific examples include: fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted cycloalkyloxy groups, ester groups (-COOR), alkylsulfonyl groups, cycloalkylsulfonyl groups, carboxyl groups, cyano groups, nitro groups, etc.

[0143] n1 is preferably 1 to 3, more preferably 1 or 2. n2 is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0144] As specific examples of the first structural unit, the structural units represented by the following formulas can be listed. However, the first structural unit is not limited to these specific examples.

[0145] [Chemistry 17]

[0146]

[0147] [Chemistry 18]

[0148]

[0149] (where R) 50 (e.g., hydrogen atom, fluorine group, methyl group, or trifluoromethyl group)

[0150] In polymer (A), the content of the first structural unit relative to the total amount of structural units in polymer (A) is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 25 mol% or more. Furthermore, the content of the first structural unit relative to the total amount of structural units in polymer (A) is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less. By setting the content of the first structural unit within the aforementioned range, the CDU performance of this composition can be improved.

[0151] (Second structural unit)

[0152] The second structural unit is a structural unit with an acid-dissociable group, which is typically introduced into polymer (A) to adjust the solubility or sensitivity of polymer (A) in the developer. In this specification, structural units having both an acid-dissociable group and a hydroxyl group bonded to an aromatic ring are classified as second structural units.

[0153] Furthermore, in this specification, the structural unit having an acid-dissociable group in polymer (F) is designated as "structural unit (ii)," and the structural unit having an acid-dissociable group in polymer (A) is designated as "second structural unit." The structural unit (ii) contained in polymer (F) of this composition may be the same as or different from the second structural unit contained in polymer (A).

[0154] The second structural unit only needs to have an acid-dissociable group and is not particularly limited. Examples of second structural units include the structural unit represented by formula (4-1), the structural unit represented by formula (4-2), and the structural unit represented by formula (4-3).

[0155] In polymer (A), the content of the second structural unit 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 structural units in polymer (A). Furthermore, the content of the second structural unit is preferably 65 mol% or less, more preferably 60 mol% or less, and even more preferably 55 mol% or less, relative to the total amount of structural units in polymer (A). By setting the content of the second structural unit within the aforementioned range, the difference in dissolution rate between the exposed and unexposed portions relative to the developer can be moderately increased while maintaining the sensitivity of the composition, resulting in better LWR and CDU performance of the composition.

[0156] Third structural unit

[0157] Polymer (A) may also further comprise a structural unit having an onium salt structure formed by a radiosensitive linear onium cation and an organic anion (designated as the "third structural unit"). In the third structural unit, it is assumed that the radiosensitive linear onium cation decomposes under the influence of radiation, thereby releasing the organic anion. The released organic anion then forms hydrogen bonds with components contained in the composition (e.g., a radiosensitive linear acid generator or acid diffusion control agent, solvent, etc.), thereby generating an acid derived from the organic anion. Examples of organic anions include sulfonate anions and carboxylate anions. Furthermore, in this specification, "radiation" includes electron beams (visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), etc.) and electromagnetic waves (X-rays, gamma rays, etc.).

[0158] When the organic anion in the third structural unit is a sulfonate anion, the third structural unit is considered to function primarily as a radiosensitive linear acid generator by producing a strong acid that induces the dissociation of acid dissociative groups under normal conditions. Conversely, when the organic anion in the third structural unit is a carboxylate anion, the third structural unit is considered to function primarily as an acid diffusion control agent by producing a weak acid that does not induce the dissociation of acid dissociative groups under normal conditions. Furthermore, "normal conditions" as described here refers to post-exposure bake (PEB) conditions at 110°C for 60 seconds.

[0159] The third structural unit is typically derived from monomers possessing radiosensitive linear ononium cations, organic anions, and polymerization-participating groups. Regarding the third structural unit, organic anions (-SO3-) can be... - or -COO - The third structural unit is preferably an organic anion bonded to the polymer backbone via a linker group, forming a relative ion with the radiosensitive linear ononium cation. Alternatively, the radiosensitive linear ononium cation can be bonded to the polymer backbone via a linker group, forming a relative ion with the organic anion. In terms of improving the LWR or CDU performance of this composition, the third structural unit is preferably an organic anion bonded to the polymer backbone via a linker group, more preferably a sulfonate anion (-SO3-). - It bonds to the polymer backbone via a linker group.

[0160] From the viewpoint of improving the sensitivity of this composition, the radiosensitive linear cation in the third structural unit is preferably a sulfonium cation or a monazine cation, more preferably a triarylsulfonium cation or a diarylmonazine cation. From the viewpoint of further improving the sensitivity of this composition, it is preferable that the aromatic ring (i.e., with S) present in the triarylsulfonium cation or the diarylmonazine cation is... + Or I + The aromatic ring of the bond has one or more of the following: an iodide group, a fluorine group, and a fluoroalkyl group. The fluoroalkyl group is preferably trifluoromethyl.

[0161] When at least a portion of the third structural unit contained in polymer (A) has an iodine group in the structural unit, the sensitivity can be further improved while maintaining the LWR or CDU performance of the composition well, which is preferred in this respect. When the third structural unit has an iodine group, the iodine group is preferably bonded to an aromatic ring. In addition, when the third structural unit has an iodine group, the radiosensitive linear ononium cation may have an iodine group, the organic anion may have an iodine group, or both the radiosensitive linear ononium cation and the organic anion may have an iodine group.

[0162] Specific examples of the third structural unit include structural units represented by the following formulas. However, the specific examples of the third structural unit are not limited to these.

[0163] [Chemistry 19]

[0164]

[0165] (where R) 40 It can be a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. + It is a radiosensitive linear ononium cation. J - (Sulfate anion or carboxylate anion)

[0166] When polymer (A) contains a third structural unit, the proportion of the third structural unit in polymer (A) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, relative to the total amount of structural units in polymer (A). Furthermore, the proportion of the third structural unit in polymer (A) is preferably 25 mol% or less, more preferably 20 mol% or less, relative to the total amount of structural units in polymer (A). By setting the proportion of the third structural unit within the aforementioned range, the LWR performance or CDU performance of this composition can be sufficiently improved.

[0167] Fourth structural unit

[0168] Polymer (A) is a structural unit having a lactone structure, a cyclic carbonate structure, or a sulfonolactone structure, or a combination of two or more of these cyclic structures (except for those that correspond to the first to third structural units, which are designated as the "fourth structural unit").

[0169] Specific examples of the fourth structural unit include structural units represented by the following formulas. However, the specific examples of the fourth structural unit are not limited to these.

[0170] [Chemistry 20]

[0171]

[0172] [Chemistry 21]

[0173]

[0174] [Chemistry 22]

[0175]

[0176] (where R) L1 (Among hydrogen atoms, fluorine atoms, methyl groups, or trifluoromethyl groups)

[0177] When polymer (A) contains a fourth structural unit, the content of the fourth structural unit is preferably 2 mol% or more, more preferably 5 mol% or more, relative to the total amount of structural units in polymer (A). Furthermore, the content of the fifth structural unit in polymer (A) is preferably 35 mol% or less, more preferably 25 mol% or less, relative to the total amount of structural units in polymer (A).

[0178] Fifth structural unit

[0179] The fifth structural unit is a structural unit having an alcoholic hydroxyl group (except for those conforming to the first to fourth structural units). By introducing the fifth structural unit into the polymer (A), the effect of suppressing development defects when forming a resist pattern from this composition can be improved. Here, in this specification, "alcoholic hydroxyl group" refers to a group having a structure in which a hydroxyl group is directly bonded to an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a chain hydrocarbon group or an alicyclic hydrocarbon group.

[0180] The fifth structural unit is preferably a structural unit derived from an unsaturated monomer having an alcoholic hydroxyl group. The structure of the unsaturated monomer providing the fifth structural unit is not particularly limited. Specific examples of the fifth structural unit include structural units represented by the following formulas. However, the specific examples of the fifth structural unit are not limited to these.

[0181] [Chemistry 23]

[0182]

[0183] (where R) A (Among hydrogen atoms, fluorine atoms, methyl groups, or trifluoromethyl groups)

[0184] When polymer (A) contains a fifth structural unit, from the viewpoint of improving the effect of suppressing development defects in the resist pattern, the content of the fifth structural unit is preferably 1 mol% or more, more preferably 3 mol% or more, relative to the total amount of structural units in polymer (A). Furthermore, the content of the fifth structural unit is preferably 30 mol% or less, more preferably 20 mol% or less, relative to the total amount of structural units in polymer (A).

[0185] In addition to those listed above, structural units comprising polymer (A) may include, for example, structural units containing cyano, nitro, or sulfonamide groups (specifically, structural units derived from 2-cyanomethyladamantane-2-yl ester of (meth)acrylate, etc.); structural units containing non-acid-dissociable hydrocarbon groups (specifically, structural units derived from styrene or halogenated styrene (e.g., styrene units, bromostyrene units, etc.), structural units derived from vinylnaphthalene, structural units derived from n-pentyl ester of (meth)acrylate, etc.); and structural units derived from (meth)acrylic acid, etc. The proportions of these structural units may be suitably set according to each structural unit without impairing the effects of the present invention.

[0186] From the viewpoint of obtaining a radiosensitive linear composition with excellent sensitivity, it is preferable that the polymer (A) has iodine groups. When the polymer (A) has iodine groups, only one of the first to fifth structural units may have iodine groups, or two or more may have iodine groups. In addition, for example, when the first structural unit has iodine groups, a portion of the first structural unit may have iodine groups, or all of the first structural units may have iodine groups.

[0187] The weight-average molecular weight (Mw) of polymer (A) obtained by GPC from polystyrene is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and even more preferably 4,000 or more. Furthermore, the Mw of polymer (A) 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. By setting the Mw of polymer (A) within the aforementioned range, the coatability of this composition can be improved, and development defects can be sufficiently suppressed; therefore, this is preferable.

[0188] The ratio of the molecular weight (Mw) of polymer (A) to the number average molecular weight (Mn) of polystyrene obtained by GPC (Mw / Mn, hereinafter also referred to as "dispersion") is preferably 5.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less. In addition, Mw / Mn is generally 1.0 or more.

[0189] In this composition, the content of polymer (A) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 85% by mass or more, relative to the total amount of solid components contained in the composition. Furthermore, polymer (A) can also be synthesized, similarly to polymer (F), by polymerizing the monomers providing each structural unit in a suitable solvent using a known free radical polymerization initiator or the like.

[0190] Furthermore, when this composition contains polymer (A) and polymer (F), the content of polymer (F) in this composition is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of polymer (A). Additionally, the content of polymer (F) is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, relative to 100 parts by mass of polymer (F).

[0191] (Other solvents)

[0192] This composition may also contain compound (S) and other solvents. The other solvents are preferably solvents capable of dissolving or dispersing the components formulated in this composition. Specific examples of other solvents include various organic solvents, such as alcohols, ethers, ketones, amides, esters, hydrocarbons, etc. From the viewpoint of ensuring good film thickness uniformity, at least one of these is preferably selected from the group consisting of alcohols, ethers, ketones, and esters.

[0193] Examples of alcohols include: aliphatic monools with 1 to 18 carbon atoms, such as 4-methyl-2-pentanol and n-hexanol; alicyclic monools with 3 to 18 carbon atoms, such as cyclohexanol; polyols with 2 to 18 carbon atoms, such as 1,2-propanediol; and some ethers of polyols with 3 to 19 carbon atoms, such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, and propylene glycol mono-n-butyl ether.

[0194] Examples of ethers include: dialkyl ethers such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisopentyl ether, dihexyl ether, and diheptyl ether; cyclic ethers such as tetrahydrofuran and tetrahydropyran; and ethers containing aromatic rings such as diphenyl ether and anisole.

[0195] Examples of ketones include: acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, 2-heptanone, ethyl n-butyl ketone, methyl n-hexyl ketone, diisobutyl ketone, trimethylnonanone, and other chain ketones; cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, and other cyclic ketones; 2,4-pentanedione, acetone-acetone, acetophenone, diacetone alcohol, etc.

[0196] Examples of amides include: cyclic amides such as N,N'-dimethylimidazolidineone and N-methylpyrrolidone; and chain amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0197] Examples of esters include: monocarboxylic acid esters such as n-butyl acetate and ethyl lactate; polyol carboxylic acid esters such as propylene glycol diacetate; polyol partial ether carboxylic acid esters such as propylene glycol monomethyl ether acetate; polycarboxylic acid diesters such as diethyl oxalate; carbonates such as dimethyl carbonate and diethyl carbonate; and cyclic esters such as γ-butyrolactone.

[0198] 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.

[0199] When this composition contains other solvents, from the viewpoint of improving the storage stability of this composition, the content of other solvents is preferably 90% by mass or less relative to the total amount of solvents contained in this composition. From this viewpoint, the content of other solvents is more preferably 85% by mass or less relative to the total amount of solvents contained in this composition, more preferably 80% by mass or less, further preferably 75% by mass or less, and particularly preferably 70% by mass or less.

[0200] As other solvents, compounds having hydroxyl groups (hereinafter also referred to as "hydroxyl-containing compounds") may preferably be used. The hydroxyl-containing compounds are preferably at least one selected from the group consisting of alcohols and ketones, more preferably at least one selected from the group consisting of polyol fractional ethers having 3 to 19 carbon atoms and diacetone alcohol. When the composition contains other solvents, the content of the hydroxyl-containing compound in the composition is preferably 25% by mass or more, more preferably 35% by mass or more, and even more preferably 50% by mass or more, relative to the total amount of the other solvents.

[0201] (Radiosensitive linear acid generator)

[0202] A radiosensitive linear acid generator is a substance that produces acid upon irradiation with radiation. Radiosensitive linear acid generators can be ionic or non-ionic. Preferably, they are ionic, and ononium salts containing a radiosensitive linear ononium cation and an organic anion that is the conjugate base of the acid are preferred. The organic anion is typically an anion obtained by removing a proton from the acid group of an organic acid.

[0203] The radiosensitive linear acid generator can be either a so-called radiosensitive linear acid generator or an acid diffusion control agent. Furthermore, this composition may contain both an acid generator and an acid diffusion control agent as a radiosensitive linear acid generator. Here, the acid generator is a substance that generates a strong acid in this composition upon exposure, enabling the acid-dissociating groups of the components in the radiosensitive linear composition to dissociate from other components. The acid diffusion control agent is a substance that inhibits the diffusion of acid from the acid generator generated by exposure into the resist film, thereby inhibiting acid-induced chemical reactions in non-exposed areas. The radiosensitive linear acid generator is classified as an acid generator or an acid diffusion control agent based on the relative acid strength to the components in this composition (specifically, a polymer (A) containing a third structural unit, or other radiosensitive linear acid generators containing two or more radiosensitive linear acid generators). Furthermore, the degree of acidity can be evaluated by the acid dissociation constant (pKa). For example, the acid dissociation constant of the acid produced by the acid diffusion control agent is usually -3 or higher, preferably -1≦pKa≦7, and more preferably 0≦pKa≦5.

[0204] The radiosensitive linear acid generator can be any component different from polymers (F) and (A), and can be a low-molecular-weight compound (also called a non-polymer) without a specific molecular weight distribution, or it can be a polymer. From the perspective of ease of adjustment of the sensitivity of this composition and high freedom of choice in selecting the radiosensitive linear acid generator formulated in this composition, a low-molecular-weight compound (non-polymer) is preferably used as the radiosensitive linear acid generator. The molecular weight of the radiosensitive linear acid generator is preferably 1,000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0205] Acid generating agent

[0206] The type of acid generator formulated in this composition is not particularly limited, and known radiosensitive linear acid generators used in resist patterning can be used. The acid generator is preferably a compound that, under the aforementioned general conditions, produces an acid (preferably a strong acid such as sulfonic acid, imide acid, or methyl acid) in the composition with a higher acidity than that produced by the acid diffusion control agent (more specifically, a photodegradable base), thereby inducing the dissociation of acid dissociative groups.

[0207] When using onium salts as acid generators, from the viewpoint of achieving high sensitivity of the composition and forming a resist film with superior photolithographic properties, the acid generator is preferably a sulfonium cation or a monazine cation, more preferably an arylsulfonium cation or an arylmonazine cation. Specific examples of radiosensitive linear onium cations include cations represented by the following formulas.

[0208] [Chemistry 24]

[0209]

[0210] [Chemistry 25]

[0211]

[0212] [Chemistry 26]

[0213]

[0214] [Chemistry 27]

[0215]

[0216] [Chemistry 28]

[0217]

[0218] The organic anion possessed by the acid generating agent is not particularly limited, but sulfonate anions, imide anions, or methylated anions are preferred in terms of improving the sensitivity of the composition. For example, specific examples of sulfonate anions include anions represented by the following formulas.

[0219] [Chemistry 29]

[0220]

[0221] [Chemistry 30]

[0222]

[0223] [Chemistry 31]

[0224]

[0225] When an acid-generating agent is incorporated into this composition, from the viewpoint of fully obtaining the sensitivity improvement effect brought about by the incorporation of the acid-generating agent, the content of the acid-generating agent 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, relative to 100 parts by mass of polymer (A). Furthermore, from the viewpoint of suppressing the generation of development defects caused by the acid-generating agent, the content ratio of the acid-generating agent is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of polymer (A).

[0226] In terms of further improving the CDU performance of this composition by incorporating an acid-generating agent, an onium salt having iodine atoms is preferably used as the acid-generating agent. Among the acid-generating agents having iodine atoms, the number of iodine atoms per molecule is preferably two or more, from the viewpoint of sufficiently improving the CDU performance of the radiosensitive linear composition. In the case of an organic anion having one or more iodine atoms in the acid-generating agent, the sensitivity and CDU performance of this composition can be improved in a good balance, which is preferable in this respect. Furthermore, in the case of a radiosensitive linear onium cation having one or more iodine atoms, the CDU performance of this composition can be further improved, which is preferable in this respect. Moreover, in the case of a radiosensitive linear onium cation having one or more iodine atoms, the radiosensitive linear onium cation can be a monazine cation, or it can be a sulfonium cation having an iodine group.

[0227] Acid diffusion control agent

[0228] From the viewpoint of achieving good photolithographic properties in this composition, it is preferable that the composition contains an onium salt (hereinafter also referred to as "photodegradable base") having a radiosensitive linear onium cation and an organic anion that is a conjugate base as an acid, as an acid diffusion control agent. The photodegradable base is preferably an onium salt that generates carboxylic acid, sulfonic acid, or sulfonamide by exposure. Furthermore, from the perspective of forming a resist film with higher photolithographic performance, an onium salt having a sulfonium cation or a monazite cation is preferably used as the photodegradable base.

[0229] Specific examples of radiosensitive linear ononium cations that can be present in photodegradable bases include ononium cations that are the same as those that can be present in acid-generating agents.

[0230] Organic anions that are photodegradable bases include, for example, anions represented by the following formulas.

[0231] [Chemistry 32]

[0232]

[0233] When the acid diffusion control agent is incorporated into this composition, from the viewpoint of fully obtaining the improvement effect on sensitivity, CDU performance, and film thickness uniformity, the content of the acid diffusion control agent is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of polymer (A). Furthermore, from the viewpoint of suppressing the generation of development defects caused by the acid diffusion control agent, the content ratio of the acid diffusion control agent is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, relative to 100 parts by mass of polymer (A).

[0234] When an acid diffusion control agent is incorporated into this composition, the content of the acid diffusion control agent in the composition is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total amount of the acid generating agent contained in the composition and the monomer providing the third structural unit in polymer (A). Furthermore, the content ratio of the acid diffusion control agent is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less, relative to the total amount of the acid generating agent contained in the composition and the monomer providing the third structural unit. By setting the content ratio of the acid diffusion control agent within the aforementioned range, the CDU performance of this composition can be further improved.

[0235] In terms of further improving the CDU performance of this composition by incorporating an acid diffusion control agent, an onium salt having iodine atoms is preferably used as the acid diffusion control agent. From the viewpoint of sufficiently improving the CDU performance of the radiosensitive linear composition, the number of iodine atoms per molecule of the acid diffusion control agent is preferably one or more, more preferably two or more. When the organic anion in the acid diffusion control agent has one or more iodine atoms, the sensitivity, CDU performance, and film thickness uniformity of this composition can be improved in a balanced manner, which is preferable in this respect. Furthermore, when the organic anion has two or more aromatic rings and hydroxyl groups bonded to said aromatic rings, the sensitivity and CDU performance of this composition are excellent, which is preferable in this respect.

[0236] (Any other ingredients)

[0237] This composition may also contain components (hereinafter also referred to as "other arbitrary components") that are different from the polymer (F), compound (S), polymer (A), radiosensitive linear acid generator, and other solvents. Examples of other arbitrary components include: surfactants, compounds containing alicyclic skeletons (e.g., 1-adamantanecarboxylic acid, 2-adamantaneone, tert-butyl deoxycholate, etc.), sensitizers, and precession promoters. The content of other arbitrary components may be suitably set according to each compound without impairing the effects of the present invention.

[0238] <Method for manufacturing radiosensitive linear composition>

[0239] This composition can be manufactured, for example, by mixing the polymer (F) and compound (S), and other components as needed, in a desired proportion, preferably by filtering the resulting mixture using a filter (e.g., a filter with a pore size of about 0.2 μm). The solids 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 solids 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 solids concentration of this composition within the aforementioned range, good coatability and a good resist pattern shape are achieved, which is preferable in this respect.

[0240] The composition thus obtained can also be used as a positive pattern forming composition for forming patterns using an alkaline developer, or as a negative pattern forming composition for forming patterns using a developer containing an organic solvent.

[0241] Method for forming resist patterns

[0242] The resist pattern forming method of 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 by the coating step (hereinafter also referred to as the "exposure step"); and a step of developing the resist film exposed by the exposure step (hereinafter also referred to as the "development step"). Examples of patterns formed by the resist pattern forming method of this disclosure include line and space patterns, hole patterns, etc. Because the resist pattern forming method of this disclosure uses the composition to form the resist film, it can form resist patterns with good sensitivity and CDU performance and few development defects. Each step will be described below.

[0243] [Coating Process]

[0244] In the coating process, a resist film is formed on a substrate by coating this composition onto one side of the substrate. The substrate for forming the resist film can be any known material, such as a silicon wafer, silicon dioxide, or an aluminum-coated wafer. Alternatively, an organic or inorganic antireflective film, as disclosed in Japanese Patent Application Publication No. 59-93448, can be formed on the substrate. The coating method for this composition can include, for example, spin coating, cast coating, or roll coating. A soft bake (hereinafter also referred to as "SB") can be performed after coating to evaporate the solvent in the coating film. The SB temperature is preferably 60°C or higher, more preferably 80°C or higher. Furthermore, the SB temperature is preferably 140°C or lower, more preferably 120°C or lower. The SB time is preferably 5 seconds or higher, more preferably 10 seconds or higher. Furthermore, the SB time is preferably 600 seconds or lower, more preferably 300 seconds or lower. The average thickness of the formed resist film is preferably 10 nm to 1,000 nm, more preferably 20 nm to 500 nm. Furthermore, soft baking is also referred to as pre-baking.

[0245] [Exposure Process]

[0246] In the exposure process, the resist film obtained through the coating process is exposed to radiation. This exposure is performed by irradiating the resist film with radiation through a photomask, or, where appropriate, a liquid immersion medium such as water. The radiation, depending on the linewidth of the target pattern, can be categorized as: visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, gamma rays, and other electromagnetic waves; electron beams, alpha rays, and other charged particle beams. Of these, the radiation irradiating the resist film formed using this composition is preferably far ultraviolet light, EUV, or an electron beam; more preferably, it is ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, or an electron beam; even more preferably, it is ArF excimer laser light, EUV, or an electron beam; even more preferably, it is EUV or an electron beam; and particularly preferably, it is EUV.

[0247] Preferably, post-exposure baking (PEB) is performed after the exposure, thereby promoting the dissociation of acid-dissociating groups in the exposed portions of the resist film by acid generated from compounds that produce acid through exposure (such as radiosensitive linear acid generators). Through PEB, the difference in solubility of the exposed and unexposed portions relative to the developer can be increased. 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 time is preferably 5 seconds or higher, more preferably 10 seconds or higher. Furthermore, the PEB time is preferably 600 seconds or lower, more preferably 300 seconds or lower.

[0248] [Developing process]

[0249] In the developing process, the exposed resist film is developed. This forms the desired resist pattern. Generally, after development, the film is rinsed with a solution such as water or alcohol and then dried. The developing method in the developing process can be alkaline development or organic solvent development.

[0250] In the case of alkaline development, the developing solution used for development may include, for example, an alkaline aqueous solution prepared by dissolving at least one of the following alkaline compounds: sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl diethylamine, ethyl dimethylamine, 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, an aqueous solution of TMAH is preferred, and a 2.38% by mass aqueous solution of TMAH is more preferred. In the case of organic solvent development, the developing solution may include one or more of the following: organic solvents such as hydrocarbons, ethers, esters, ketones, and alcohols; and solvents containing the aforementioned organic solvents.

[0251] Examples of development methods include: immersing a substrate in a tank filled with developer for a fixed time (immersion method); developing a substrate by using surface tension to accumulate developer on the substrate surface and then allowing it to stand for a fixed time (puddle method); spraying developer onto the substrate surface (spray method); and continuously spraying developer onto a substrate rotating at a fixed speed while scanning the developer nozzle at a fixed speed (dynamic distribution method), etc.

[0252] Example

[0253] The present invention will be specifically described below with reference to synthetic examples, embodiments, and comparative examples, but the present invention is not limited to the embodiments described below. Furthermore, unless otherwise specified, "parts" and "%" in the following examples refer to mass.

[0254] The following shows the methods for determining the various physical properties of polymers.

[0255] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)]

[0256] The Mw and Mn of the polymer were determined by gel permeation chromatography (GPC) using GPC columns manufactured by Tosoh Corporation (2 “G2000HXL”, 1 “G3000HXL”, and 1 “G4000HXL”) under the following conditions.

[0257] Eluent: Tetrahydrofuran (manufactured by Fujifilm and Kazumitsu Chemical Co., Ltd.)

[0258] Flow rate: 1.0 mL / min

[0259] Sample concentration: 1.0% by mass

[0260] Sample injection volume: 100 μL

[0261] Column temperature: 40℃

[0262] Detector: Differential refractometer

[0263] Standard material: Monodisperse polystyrene

[0264] <[P] Polymer Synthesis>

[0265] [Synthetic Examples A1 to A36] Synthesis of Basic Polymers (A-1) to (A-36)

[0266] The monomers were combined and copolymerized in tetrahydrofuran (THF) solvent. Crystallization was carried out in methanol, followed by repeated washing with hexane. Separation and drying were performed to obtain the base polymers (A-1) to (A-36) with the compositions shown in Table 1. 1 The composition of the obtained base polymer was confirmed by 1H-NMR, and the Mw and dispersion (Mw / Mn) were confirmed by the GPC conditions. The types and proportions of each monomer are shown in Table 1.

[0267] [Chemistry 33]

[0268]

[0269] [Chemistry 34]

[0270]

[0271] [Table 1]

[0272]

[0273] <[F] Polymer Synthesis>

[0274] [Synthesis Example F1] (Synthesis of a high-fluorine-content polymer (F-1))

[0275] Monomers (E-1) and (M-6) were dissolved in 2-butanone at a molar ratio of 70 / 30 to obtain the final polymer, and AIBN (azobisisobutyronitrile) was added as an initiator to prepare a monomer solution. 2-Butanone was added to a reaction vessel, and the vessel was purged with nitrogen for 30 minutes. The reaction vessel was set to 80°C, and the monomer solution was added dropwise while stirring, and polymerization was carried out for 6 hours. Afterward, the polymerization solution was cooled to below 30°C. The solvent was replaced with acetonitrile, hexane was added, and the mixture was stirred and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of the high-fluorine polymer (F-1) was obtained.

[0276] pass 13 The composition of the obtained high-fluorine polymer was confirmed by C-NMR, and the Mw and dispersity (Mw / Mn) were confirmed by the GPC conditions. The Mw and dispersity (Mw / Mn) are shown in Table 2 along with the types and proportions of monomers.

[0277] Synthesis of high-fluorine polymers (F-2) to (F-25), (Fc-1), and (Fc-2) [Synthesis Examples F2 to F27]

[0278] In Synthesis Example F1, except for changing the monomers used, high-fluorine polymers (F-2) to (F-25), high-fluorine polymers (Fc-1) and (Fc-2) were obtained in the same manner as in Synthesis Example F1. The types and proportions of monomers constituting each polymer, as well as Mw and dispersion (Mw / Mn), are shown in Table 2.

[0279] [Chemistry 35]

[0280]

[0281] [Table 2]

[0282]

[0283] <Preparation of Radiosensitive Linear Compositions>

[0284] The following shows the [B] radiosensitive linear acid generator, [D] acid diffusion control agent, and [S] solvent used in the preparation of the radiosensitive linear compositions of Examples 1-85 and Comparative Examples 1-3.

[0285] [B] Radiosensitive linear acid generator

[0286] The compounds represented by the following formulas (B-1) to (B-12) are used as radiosensitive linear acid generators.

[0287] [Chemistry 36]

[0288]

[0289] [Chemistry 37]

[0290]

[0291] [D] Acid diffusion control agent

[0292] The compounds represented by the following formulas (D-1) to (D-8) are used as acid diffusion control agents.

[0293] [Chemistry 38]

[0294]

[0295] [S]solvent

[0296] Use the following solvents (S-1) to (S-6) as solvents.

[0297] (S-1): PGMEA (Propylene Glycol Monomethyl Ether Acetate)

[0298] (S-2): HBM (methyl 2-hydroxyisobutyrate)

[0299] (S-3): PGME (Propylene Glycol Monomethyl Ether)

[0300] (S-4): DAA (diacetone alcohol)

[0301] (S-5): HBE (ethyl 2-hydroxyisobutyrate)

[0302] (S-6): HBP (isopropyl 2-hydroxyisobutyrate)

[0303] [Example 1]

[0304] 100 parts by weight of (A-1) as polymer [A], 45 parts by weight of (B-7) as radiosensitive linear acid generator [B], 35 mol% of (D-1) as acid diffusion control agent [D] relative to (B-7), 5 parts by weight of (F-1) as high fluoride polymer [F], 2,000 parts by weight of (S-1) as solvent [S], 4,000 parts by weight of (S-2) and 4,000 parts by weight of (S-3) as solvent [S]. The radiosensitive linear composition (R-1) was prepared by filtering it using a 0.2 μm pore size membrane filter.

[0305] [Examples 2-85 and Comparative Examples 1-3]

[0306] Except for using the types and amounts of each component shown in Tables 3, 4, and 5, the same procedures were followed as in Example 1 to prepare radiosensitive linear compositions (R-2) to (R-85) and radiosensitive linear compositions (CR-1) to (CR-3). In Tables 3, 4, and 5, the content of the [D] acid diffusion control agent represents the ratio (mol%) relative to the total amount of the [B] radiosensitive linear acid generator and the monomer providing the third structural unit in the [A] polymer.

[0307] [Table 3]

[0308]

[0309] [Table 4]

[0310]

[0311] [Table 5]

[0312]

[0313] <Formation of resist patterns for defect suppression evaluation>

[0314] The prepared radiosensitive linear compositions were coated onto the surface of a 12-inch silicon wafer with a 20 nm thick lower layer film (AL412, Brewer Science) using a spin coater (CLEAN TRACK ACT12, Tokyo Electron). After a 60-second SB (soft bake) at 100°C, the wafer was cooled at 23°C for 30 seconds to form a 45 nm thick resist film. Next, the resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3400", ASML, NA=0.33, illumination conditions: Conventional s=0.89). The EUV-exposed resist film was then subjected to a 60-second PEB (post-exposure bake) at 110°C. Subsequently, a positive 48 nm pitch - 24 nm contact hole pattern was formed by developing a 2.38 wt% TMAH aqueous solution at 23 °C for 30 seconds.

[0315] [Evaluation of Defect Suppression]

[0316] The number of defects in the formed contact hole pattern was determined using a defect inspection device (KLA-Tencor's "KLA2925"). The observed defects were categorized as either defects determined to originate from the resist film or foreign matter from the external environment. Regarding the number of developed defects, a score of "A" (Good) was given for 50 or fewer defects determined to originate from the resist film; "B" (Slightly Good) for more than 50 but less than 100; and "C" (Poor) for more than 100. The evaluation results are shown in Tables 6 and 7.

[0317] <Formation of resist pattern for preservation stability evaluation> (KrF exposure, alkaline development)

[0318] The prepared radiosensitive linear composition was coated onto the surface of a 12-inch silicon wafer with a 20 nm thick lower layer film (DUV42, manufactured by Nissan Chemical Co., Ltd.) using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron). After spin coating at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 45 nm thick resist film. Next, the resist film was irradiated with KrF light using a KrF exposure machine (model "S210D", manufactured by Nikon, NA=0.55, illumination conditions: Annular s=0.8, mask 150 nm LS). The resist film was then subjected to PEB at 90°C for 60 seconds. Subsequently, it was developed using a 2.38 wt% TMAH aqueous solution at 23°C for 30 seconds to form a positive 150 nm line and space pattern.

[0319] [Evaluation of preservation stability]

[0320] After preparing the radiosensitive linear composition, a portion was stored at -15°C for three weeks, and the remainder was stored at 35°C for three weeks. Subsequently, in resist patterning using the KrF exposure, the optimal exposure for forming 150 nm lines and spatial patterns was determined. Based on the optimal exposure of the radiosensitive linear composition after storage at -15°C for three weeks, cases where the optimal exposure of the radiosensitive linear composition after storage at 35°C for three weeks resulted in a sensitivity increase of 1.2% or more, or a sensitivity decrease of 1.2% or more, were classified as "C"; cases where the sensitivity increase was less than 1.2% but more than 0.6%, or a sensitivity decrease was less than 1.2% but more than 0.6%, were classified as "B"; and all other cases were classified as "A". The evaluation results are shown in Tables 6 and 7.

[0321] [Table 6]

[0322]

[0323] [Table 7]

[0324]

[0325] As shown in Tables 6 and 7, the defect suppression and storage stability of the radiosensitive linear compositions of Examples 1 to 85 were rated as A or B. In contrast, the storage stability of the radiosensitive linear composition containing polymer (F) but not compound (S) (Comparative Example 1) was rated as C. Furthermore, the defect suppression of the radiosensitive linear compositions containing compound (S) but not polymer (F) (Comparative Examples 2 and 3) was rated as C. Based on these results, it can be said that the radiosensitive linear compositions of Examples 1 to 85 can achieve a good balance between defect suppression and storage stability.

[0326] As described above, the radioactive linear composition and resist patterning method of this disclosure can effectively improve defect suppression and storage stability. Therefore, the radioactive linear composition and resist patterning method of this disclosure are preferably used in the processing technology of semiconductor devices that are expected to be further miniaturized in the future.

Claims

1. A radiosensitive composition comprising: Polymer (F), comprising structural units having fluorine atoms and base-dissociable groups; and The compound is represented by the following formula (1). [Chemistry 1] (In equation (1), R) 11 R 12 and R 13 (Each group is a monovalent aliphatic hydrocarbon group with 1 to 20 carbon atoms).

2. The radiosensitive linear composition according to claim 1 further comprises a polymer (A), said polymer (A) comprising a structural unit having an aromatic ring and a hydroxyl group bonded to said aromatic ring.

3. The radiosensitive linear composition according to claim 2, wherein the polymer (A) further comprises a structural unit having an acid-dissociable group.

4. The radiosensitive linear composition according to claim 1, wherein the structural unit having fluorine atoms and base dissociative groups is represented by the following formula (2). [Chemistry 2] (In equation (2), R) F It can be a hydrogen atom, a fluorine group, a methyl group, a trifluoromethyl group, or a methoxymethyl group. A 1 It can be a single bond, -O-, -CO-, -COO-, -NH-, or -CONH-. R 21 It is a hydrocarbon group with a valence of (s+1) having 1 to 20 carbon atoms, or it is an R group of the hydrocarbon group. 22 The terminal bonds on the side contain oxygen atoms, sulfur atoms, and -NR. 24 - A group consisting of a carbonyl group, a sulfonyl group, a -CO-O- group, or a -CO-NH- group, or a group with a heterocyclic structure and a (s+1) valence of 3 to 20 carbon atoms. R 24 It can be a hydrogen atom or a monovalent organic group. R 22 It is a single bond or a divalent fluorinated chain hydrocarbon group with 1 to 20 carbon atoms. X 1 For oxygen atoms, -CO-O- or -SO2-O- . "Indicates to R" 23 The bond structure. R 23 It is a monovalent organogroup with 1 to 30 carbon atoms. In X 1 -CO-O- or -SO2-O- In the case of R 22 and R 23 At least one of them is in relation to X 1 A group consisting of a bonded carbon atom or a carbon atom adjacent to the said carbon atom bonded to a fluorine atom, or R 23 To have the same as X 1 A bonded aromatic ring and a fluorine atom or a trifluoromethyl group bonded to the aromatic ring. Wherein, in R 23 In, relative to X 1 The bonding positions of the fluorine atom or trifluoromethyl group with X 1 The aromatic ring of the bond is bonded at position 2 or 3. In X 1 In the case of oxygen atoms, R 22 For a single bond, R 21 R is a hydrocarbon group with a carbon number of 1 to 20 and a valence of (s+1). 23 For X 1 The group has a carbonyl group bonded to its end on one side, and a fluorine atom bonded to the carbon atom adjacent to the carbonyl group. s is an integer from 1 to 3. Where s is 2 or 3, multiple R... 22 Same or different, multiple X 1 Same or different, multiple R 23 Same or different).

5. The radiosensitive linear composition according to claim 1 further comprises a radiosensitive linear acid generator containing radiosensitive linear cations and organic anions.

6. The radiosensitive linear composition according to claim 1, comprising a compound represented by formula (1) as a solvent, The content of the compound represented by formula (1) is 10% by mass or more relative to the total amount of the solvent.

7. The radiosensitive linear composition according to claim 1, comprising the compound represented by formula (1) and other solvents different from the compound represented by formula (1) as solvents.

8. The radiosensitive linear composition according to claim 7, wherein the other solvent is at least one selected from the group consisting of alcohols, ethers, ketones and esters.

9. A method for forming a resist pattern, comprising: The process of forming a resist film on a substrate using the radiosensitive linear composition as described in any one of claims 1 to 8; The process of exposing the resist film; as well as The process of developing the exposed resist film.

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