Radiation-sensitive linear resin composition and pattern formation method

Abstract

This invention provides a radiosensitive linear resin composition and a patterning method capable of forming resist films with sufficient sensitivity or CDU performance and developer residue suppression even when using next-generation technologies. A radiosensitive linear resin composition comprises: a resin containing structural units represented by the following formula (1); one or more onium salts containing an organic acid anionic portion and an onium cation portion; and a solvent, wherein at least a portion of the onium cation portion of the onium salt contains an aromatic ring structure having a fluorine atom. (In the formula (1), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a haloalkyl group having 1 to 5 carbon atoms, Y1 is a divalent linker, and X1 is an acid-dissociable group.)

Description

Technical Field

[0001] This invention relates to a radiosensitive linear resin composition and a method for patterning. Prior Technology

[0002] Photolithography using resist compositions is employed in the formation of fine circuits for semiconductor devices. A representative process involves, for example, exposing a resist composition film to a dielectric mask pattern using radiation to generate acid. The acid then acts as a catalyst, creating a difference in solubility of the resin relative to an alkaline or organic solvent-based developer in the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] In the aforementioned photolithography technique, short-wavelength radiation such as ArF excimer lasers is used, or the reflected radiation is combined with liquid immersion lithography to advance pattern miniaturization. As a next-generation technology, the use of even shorter-wavelength radiation such as electron beams, X-rays, and extreme ultraviolet (EUV) radiation is being explored, and research is underway on acid-generating resist materials containing benzene rings to improve the absorption efficiency of such radiation (Japanese Patent Application Publication No. 2014-2359). [Existing Technical Documents] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2014-2359 Summary of the Invention

[0005] [The problem that the invention aims to solve]

[0006] In the next-generation technology, it is required that the performance of the resist be equal to or better than that of the previous resist in terms of sensitivity, critical dimension uniformity (CDU) performance as an indicator of linewidth or aperture uniformity, and suppressive ability to suppress the generation of development residue during development.

[0007] The purpose of this invention is to provide a radiosensitive linear resin composition and a patterning method that can form a resist film with sufficient sensitivity or CDU performance and development residue inhibition when using next-generation technology. [Methods for solving problems]

[0008] The inventors have made repeated efforts to solve this problem and have found that the objective can be achieved by adopting the following structure, thus completing the present invention.

[0009] In one embodiment, the present invention relates to a radiosensitive linear resin composition comprising: The resin comprises the structural unit represented by the following formula (1) (hereinafter also referred to as "structural unit (I)"); One or more onium salts comprising an organic acid anion moiety and an onium cation moiety; and Solvent, At least a portion of the onium cation portion of the onium salt comprises an aromatic ring structure having fluorine atoms. [Chemistry 1] (in the above formula (1), R is a hydrogen atom, an alkyl group with 1 to 5 carbon atoms, or a haloalkyl group with 1 to 5 carbon atoms; Y1 is a divalent linker; and X1 is an acid-dissociable group.

[0010] Based on this radiosensitive linear resin composition, a resist film satisfying sensitivity, CDU performance, and developer residue suppression can be constructed. The rationale is uncertain, but it is speculated as follows: Fluorine atoms have a very high absorption rate for EUV and other radiation at a wavelength of 13.5 nm, thereby increasing the sensitivity of the radiosensitive linear resin composition. Furthermore, utilizing the aromatic ring structure containing fluorine atoms in the ononium cation moiety, the water repellency of the resist film is improved, and intermixing between the resist film and its underlying film is suppressed, thus exhibiting developer residue suppression. Moreover, the acid-dissociating groups of the structural unit (I) in the resin, through the degree of freedom generated by the interseptate linker or ester bond, have a high probability of contact with the acid generated by exposure, thus facilitating acid dissociation reactions. Therefore, the dissolution contrast between the exposed and unexposed areas is improved, resulting in excellent pattern forming properties. It is speculated that the aforementioned resist properties are achieved through the combined effect of these factors. Furthermore, "aromatic ring structures with fluorine" include not only structures in which fluorine atoms are directly bonded to the aromatic ring structure, but also structures in which fluorine atoms are bonded to the aromatic ring structure through other atoms (e.g., structures in which fluorine atoms are bonded to substituents bonded to the aromatic ring structure).

[0011] In another embodiment of the present invention, there is a method for forming a pattern, comprising the step of directly or indirectly coating the radiosensitive linear resin composition onto a substrate to form a resist film; The step of exposing the resist film; and The step of developing the exposed resist film using a developing solution.

[0012] In this pattern forming method, since the radiosensitive linear resin composition with excellent sensitivity, CDU performance and developer residue suppression is used, high-quality resist patterns can be formed efficiently. Simple Explanation of the Diagram

[0013] none Implementation

[0014] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0015] Radiation-sensitive linear resin composition The radiosensitive linear resin composition of this embodiment (hereinafter, also simply referred to as the "composition") comprises a resin, one or more onium salts, and a solvent. The composition may also contain any other arbitrary components without impairing the effects of the present invention. By comprising the specified resin and onium salt, the radiosensitive linear resin composition can impart high levels of sensitivity, CDU performance, and developer residue suppression to the obtained resist film.

[0016] <Resin> The resin is an aggregate of polymers containing structural unit (I) (hereinafter, the resin is also referred to as "base resin"). In addition to structural unit (I), the base resin may also contain structural units with phenolic hydroxyl groups or structural units that provide phenolic hydroxyl groups through the action of an acid (hereinafter, both are also referred to as "structural unit (II)"), structural units (III) containing lactone structures, etc. Each structural unit is described below.

[0017] (Structural Unit (I)) The structural unit (I) is represented by the following equation (1). [Chemistry 2] (in the above formula (1), R is a hydrogen atom, an alkyl group with 1 to 5 carbon atoms, or a haloalkyl group with 1 to 5 carbon atoms; Y1 is a divalent linker; and X1 is an acid-dissociable group.

[0018] In the formula (1), the alkyl group represented by R, which has 1 to 5 carbon atoms, is preferably a straight-chain or branched alkyl group. Specifically, examples include: methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tributyl, pentyl, isopentyl, neopentyl, etc.

[0019] In formula (1), R can be a alkyl halide with 1 to 5 carbon atoms, which is formed by substituting some or all of the hydrogen atoms of the alkyl halide with a halogen atom. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc., with fluorine atoms being particularly preferred.

[0020] There are no particular limitations on the divalent linker of Y1. Examples of preferred choices include divalent hydrocarbon groups with substituents and divalent linkers containing heteroatoms. The term "substituents" in a hydrocarbon group refers to the fact that some or all of the hydrogen atoms in the hydrocarbon group are replaced by substituents (groups or atoms other than hydrogen atoms). The hydrocarbon group can be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Aliphatic hydrocarbon groups are hydrocarbon groups that do not possess aromaticity. The aliphatic hydrocarbon group that forms the divalent hydrocarbon group in Y1 can be saturated or unsaturated, but is usually preferred to be saturated. More specifically, examples of aliphatic hydrocarbon groups include straight-chain or branched aliphatic hydrocarbon groups and aliphatic hydrocarbon groups containing rings in their structure.

[0021] The linear or branched aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, further preferably 1 to 4, and most preferably 1 to 3. As a straight-chain aliphatic hydrocarbon group, it is preferred to be a straight-chain alkyl group, specifically including: methylene [-CH 2-], ethyl [-(CH 2) 2-], trimethylene [-(CH 2) 3-], tetramethylene [-(CH 2) 4-], pentamethylene [-(CH 2) 5-], etc. As a branched aliphatic hydrocarbon group, it is preferably a branched alkyl group. Specifically, examples include: alkylmethylene groups such as -CH(CH3)-, -CH(CH2CH3)-, -C(CH3)2-, -C(CH3)(CH2CH3)-, -C(CH3)(CH2CH2CH3)-, and -C(CH2CH3)2-; alkylethyl groups such as -CH(CH3)CH2-, -CH(CH3)CH(CH3)-, -C(CH3)2CH2-, -CH(CH2CH3)CH2-, and -C(CH2CH3)2-CH2-; alkyltrimethylene groups such as -CH(CH3)CH2CH2- and -CH2CH(CH3)CH2-; and alkyltrimethylammonium groups such as -CH(CH3)CH2CH2CH2- and -CH2CH2CH2-. 2CH(CH 3)CH 2CH 2-alkyltetramethylene alkyl alkylene ... The straight-chain or branched aliphatic hydrocarbon group may or may not have substituents.

[0022] Examples of aliphatic hydrocarbon groups containing a ring in the structure include: alicyclic hydrocarbon groups (groups after removing two hydrogen atoms from an aliphatic hydrocarbon ring) and alicyclic hydrocarbon groups bonded to the end of a straight-chain or branched aliphatic hydrocarbon group. The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms. The alicyclic hydrocarbon group can be polycyclic or monocyclic. As a monocyclic alicyclic hydrocarbon group, it is preferably a group obtained by removing two hydrogen atoms from a monocyclic alkane. The monocyclic alkane is preferably composed of 3 to 6 carbon atoms; examples include cyclopentane and cyclohexane. As a polycyclic alicyclic hydrocarbon group, it is preferably a group obtained by removing two hydrogen atoms from a polycyclic alkane; the polycyclic alkane is preferably composed of 7 to 12 carbon atoms; examples include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. The alicyclic hydrocarbon group may or may not have substituents.

[0023] Aromatic hydrocarbon groups are hydrocarbon groups that have an aromatic ring. The number of carbon atoms in the aromatic hydrocarbon group that is the divalent hydrocarbon group in Y1 is preferably 3 to 30, more preferably 5 to 30, further preferably 5 to 20, particularly preferably 6 to 15, and most preferably 6 to 10. This number of carbon atoms excludes the number of carbon atoms in the substituents. Aromatic rings, as a component of aromatic hydrocarbon groups, can be specifically exemplified by: aromatic hydrocarbon rings such as benzene, biphenyl, fluorene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which a portion of the carbon atom constituting the aromatic hydrocarbon ring is substituted by a heteroatom. Heteroatoms in aromatic heterocycles can be exemplified by: oxygen atoms, sulfur atoms, and nitrogen atoms. Specifically, examples of such aromatic hydrocarbon groups include: groups formed by removing two hydrogen atoms from the aromatic hydrocarbon ring (aryl groups); groups in which one hydrogen atom of an aryl group (aryl group) after removing one hydrogen atom from the aromatic hydrocarbon ring is substituted by an alkyl group (e.g., groups formed by further removing one hydrogen atom from an aryl group such as benzyl, phenethyl, 1-naphthylmethyl, 2-naphthylmethyl, 1-naphthylethyl, 2-naphthylethyl, etc.). The alkyl group (the alkyl chain in the aryl alkyl group) preferably has 1 to 4 carbon atoms, more preferably 1 to 2, and particularly preferably 1. The aromatic hydrocarbon group may or may not have substituents.

[0024] The so-called heteroatom in Y 1's "divalent linker containing heteroatoms" refers to atoms other than carbon and hydrogen atoms, such as oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms, etc. Examples of divalent linking groups containing heteroatoms include: -O-, -C(=O)-O-, -C(=O)-, -OC(=O)-O-, -C(=O)-NH-, -NH- (H can be substituted by alkyl, acetyl, aryl, etc.), -S-, -S(=O)2-, -S(=O)2-O-, -NH-C(=O)-, =N-, the general formula -Y21-OY22-, -[Y21-C(=O)-O]mp-Y22- or -Y21-OC(=O)-Y22- [where Y21 and Y22 are independently divalent hydrocarbon groups that can have substituents, O is an oxygen atom, and mp is an integer from 0 to 3]. When Y1 is -NH-, its H can be substituted by alkyl, acetyl, aryl (aromatic) substituents, etc. Y21 and Y22 are each independently divalent hydrocarbon groups that can have substituents. As such divalent hydrocarbon groups, the same groups listed above as "divalent hydrocarbon groups that can have substituents" in Y1 can be included. Y21 is preferably a straight-chain aliphatic hydrocarbon group, more preferably a straight-chain alkyl group, and even more preferably a straight-chain alkyl group with 1 to 5 carbon atoms, especially methylene or ethyl group. Y22 is preferably a straight-chain or branched aliphatic hydrocarbon group, and more preferably a methylene, ethyl or alkylmethylene group. As a divalent linker containing heteroatoms, it is preferably a straight-chain group having an oxygen atom as a heteroatom, such as a group containing an ether bond or an ester bond, and more preferably a group represented by the formula -Y 21-OY 22-, -[Y 21-C(=O)-O] mp-Y 22- or -Y 21-OC(=O)-Y 22-.

[0025] Of the above, the divalent linker of Y1 is preferably a straight-chain or branched alkyl group, a divalent alicyclic hydrocarbon group, or a divalent linker containing heteroatoms. Among these, a straight-chain or branched alkyl group or a divalent linker containing heteroatoms is preferred.

[0026] In the formula (1), the so-called acid-dissociable group represented by X 1 refers to a group that has acid dissociability and can break at least the bond between the acid-dissociable group and the atom adjacent to the acid-dissociable group by the action of acid.

[0027] There are no particular limitations on the acid dissociation group. Well-known examples include groups that form cyclic or chain-like tertiary alkyl esters with carboxyl groups in (meth)acrylic acid, etc.; acetal-type acid dissociation groups such as alkoxyalkyl groups, etc. Here, the term "tertiary alkyl ester" is defined as follows: an ester is formed by substituting the hydrogen atom of a carboxyl group with a chain-like or cyclic alkyl group, and a tertiary carbon atom of the chain-like or cyclic alkyl group is bonded to the oxygen atom at the end of its carbonyl oxygen group (-C(=O)-O-). In this tertiary alkyl ester, if an acid is present, the bond between the oxygen atom and the tertiary carbon atom is cleaved to form a carboxyl group. The chain-like or cyclic alkyl group may have substituents. For convenience, groups that become acid-dissociable by forming carboxyl groups and tertiary alkyl esters will be referred to as "tertiary alkyl ester type acid-dissociable groups".

[0028] As tertiary alkyl ester type acid dissociative groups, examples include aliphatic branched acid dissociative groups and acid dissociative groups containing aliphatic cyclic groups. Here, "aliphatic branched" refers to a branched structure that does not possess aromaticity. The structure of the "aliphatic branched acid dissociative group" is not limited to a group containing both carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. In addition, the "hydrocarbon group" can be either saturated or unsaturated, but is generally preferred to be saturated. Examples of aliphatic branched acidic dissociative groups include those represented by -C(R71)(R72)(R73). In these formulas, R71 to R73 are each independently a straight-chain alkyl group having 1 to 5 carbon atoms. For groups represented by -C(R71)(R72)(R73), the number of carbon atoms is preferably 4 to 8; specifically, examples include: tributyl, 2-methyl-2-butyl, 2-methyl-2-pentyl, 3-methyl-3-pentyl, etc. Tributyl is particularly preferred.

[0029] "Aliphatic cyclic group" refers to a monocyclic or polycyclic group that does not possess aromaticity. The aliphatic cyclic group in "acid-dissociable groups containing aliphatic cyclic groups" may or may not have substituents. The basic ring structure of this aliphatic cyclic group, excluding substituents, is not limited to a group containing both carbon and hydrogen (hydrocarbon group), but is preferably a hydrocarbon group. Furthermore, the hydrocarbon group can be either saturated or unsaturated, but is generally preferred to be saturated. Aliphatic cyclic groups can be monocyclic or polycyclic. Examples of aliphatic cyclic groups include those derived from monocyclic alkanes by removing one or more hydrogen atoms, and those derived from polycyclic alkanes such as bicyclic alkanes, tricyclic alkanes, and tetracyclic alkanes by removing one or more hydrogen atoms. Furthermore, a portion of the carbon atom in the ring constituting these alicyclic hydrocarbon groups may be substituted via an ether bond (-O-).

[0030] Examples of acid-dissociable groups containing aliphatic cyclic groups include those represented by formulas (1-1) to (1-9) and formulas (2-1) to (2-6).

[0031] [Chemistry 3] [In the formula, R14 represents an alkyl group, and g is an integer from 0 to 8.]

[0032] [Chemistry 4] [In the formula, R15 and R16 are each independently an alkyl group.]

[0033] In formulas (1-1) to (1-9), the alkyl group of R14 can be any of straight-chain, branched, or cyclic, preferably straight-chain or branched. The linear alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 4, and even more preferably 1 or 2. The branched alkyl group preferably has 3 to 10 carbon atoms, more preferably 3 to 5. Examples of cyclic alkyl groups are those identical to the aliphatic cyclic groups. g is preferably an integer from 0 to 3, more preferably an integer from 1 to 3, and even more preferably 1 or 2. In formulas (2-1) to (2-6), the alkyl groups of R15 to R16 can be the same as those of R14. In formulas (1-1) to (1-9) and (2-1) to (2-6), a portion of the carbon atoms constituting the ring can also be replaced by ether-type oxygen atoms (-O-). In addition, in formulas (1-1) to (1-9) and formulas (2-1) to (2-6), the hydrogen atoms bonded to the carbon atoms constituting the ring can also be substituted by substituents.

[0034] Generally speaking, the "acetal acid dissociation group" replaces the hydrogen atom at the end of a polar group containing OH, such as a carboxyl or hydroxyl group, and bonds with an oxygen atom. Moreover, the acid reacts, breaking the bond between the acetal acid dissociation group and the oxygen atom bonded to it, thus forming a polar group containing OH, such as a carboxyl or hydroxyl group.

[0035] In addition to being the acid dissociative group, X1 in formula (1) is preferably represented by formula (s1) or formula (s2) below. [Chemistry 5] (In the aforementioned formula (s1), Cy is an aliphatic cyclic group formed together with a carbon atom. Ra 01 to Ra 03 are, independently, hydrogen atoms, substituted or unsubstituted monovalent chain saturated hydrocarbon groups with 1 to 10 carbon atoms, or substituted or unsubstituted monovalent aliphatic cyclic saturated hydrocarbon groups with 3 to 20 carbon atoms, or represent an aliphatic cyclic structure formed by the combination of two or more of these, wherein the aliphatic cyclic structure does not form a cross-linked structure. In the formula (s2), Cy has the same meaning as the aforementioned formula (s1). Ra 04 is a substituted or unsubstituted aromatic hydrocarbon group. In the formula, * represents a bond with an oxygen atom.

[0036] The aliphatic cyclic group represented by Cy can be either a monocyclic or polycyclic group. As a monocyclic aliphatic cyclic group, examples include groups formed by removing one or more hydrogen atoms from a monocyclic alkane. Preferably, the monocyclic alkane has 3 to 6 carbon atoms; specifically, cyclopentane and cyclohexane are examples. As a polycyclic aliphatic cyclic group, examples include groups formed by removing one or more hydrogen atoms from a polycyclic alkane. Among these, monocyclic aliphatic cyclic groups are preferred, and more preferably groups formed by removing one or more hydrogen atoms from cyclopentane or cyclohexane.

[0037] Some or all of the hydrogen atoms in the aliphatic cyclic group may also be substituted.

[0038] In formula (s1), the monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms in Ra 01 to Ra 03 can be alkyl groups having 1 to 10 carbon atoms, for example. As monovalent aliphatic cyclic saturated hydrocarbon groups with 3 to 20 carbon atoms in Ra 01 to Ra 03, examples include monocyclic aliphatic saturated hydrocarbon groups and polycyclic aliphatic saturated hydrocarbon groups. From the perspective of the ease of synthesis of monomeric compounds from which structural unit (I) is derived, Ra 01 to Ra 03 are preferably hydrogen atoms.

[0039] The chain-like saturated hydrocarbon groups or aliphatic cyclic saturated hydrocarbon groups represented by Ra 01 to Ra 03 may or may not have substituents.

[0040] The aliphatic cyclic group represented by Cy in formula (s2) without cross-linking structure is the same as the aliphatic cyclic group represented by Cy in formula (s1).

[0041] In formula (s2), the aromatic hydrocarbon group in Ra 04 can be any group formed by removing one or more hydrogen atoms from an aromatic hydrocarbon ring having 5 to 30 carbon atoms. Ra 04 is preferably a group formed by removing one or more hydrogen atoms from an aromatic hydrocarbon ring having 6 to 15 carbon atoms, and most preferably a group formed by removing one or more hydrogen atoms from benzene.

[0042] The following are specific examples of the acid-dissociative groups represented by the formula (s1). * indicates a bonding bond.

[0043] [Chemistry 6]

[0044] [Chemistry 7]

[0045] The following are specific examples of the acid-dissociative groups represented by the formula (s2). * indicates a bonding bond.

[0046] [Chemistry 8]

[0047] The following are specific examples of the structural unit represented by equation (1). In each equation, Rα represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

[0048] [Chemistry 9]

[0049] [Chemistry 10]

[0050] [Chemistry 11]

[0051] [Chemistry 12]

[0052] The following shows specific examples of structural units (I) having the acid-dissociable groups represented by formula (s1) or formula (s2). In the following formulas, Rα represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

[0053] [Chemistry 13]

[0054] [Chemistry 14]

[0055] [Chemistry 15]

[0056] In the example described, the structural unit (I) is preferably selected from at least one of the groups of structural units represented by equations (a1-3-13) to (a1-3-24), (a1-3-33) to (a1-3-34), (s1-1) to (s1-4), and (s2-1) to (s2-6).

[0057] In the resin, the proportion of structural unit (I) (total when multiple structural units (I) are present) relative to all structural units constituting the resin is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. The aforementioned proportion is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less. By setting the proportion of structural unit (I) within the aforementioned range, the radiosensitive linear resin composition can achieve further improvement in sensitivity and CDU performance.

[0058] (Structural Unit (II)) Structural unit (II) is a structural unit having phenolic hydroxyl groups or a structural unit that provides phenolic hydroxyl groups through the action of an acid. In this invention, phenolic hydroxyl groups generated by deprotection through the action of an acid produced by exposure are also included as phenolic hydroxyl groups of structural unit (II). By including structural unit (II) in the resin, the solubility in the developer can be adjusted more appropriately, and as a result, the sensitivity of the radiosensitive linear resin composition can be further improved. In addition, when using radiation irradiated in the exposure step of a pattern forming method using KrF excimer laser light, EUV, electron beam, etc. as resist, structural unit (II) helps to improve etch resistance and the difference in developer solubility between the exposed and unexposed areas (solution contrast). In particular, it can be suitably applied to pattern forming using exposure with radiation of wavelengths below 50 nm, such as electron beam or EUV. Structural unit (II) is preferably represented by the following formula (2).

[0059] [Chemistry 16] (in the above formula (2),) Rα is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L CA represents a single bond, -COO-*, or -CONH-. * represents a bonding bond on the aromatic ring side. R 101 is a hydrogen atom or a protecting group that has been deprotected by an acid. When multiple R 101s exist, they may be the same or different from each other. R 102 is cyano, nitro, alkyl, fluorinated alkyl, alkoxycarbonyloxy, acetyl, or acetoxy. When multiple R 102s are present, they may be identical or different from each other. n3 is an integer from 0 to 2, m3 is an integer from 1 to 8, and m4 is an integer from 0 to 8. Among them, 1 ≤ m3 + m4 ≤ 2n3 + 5.

[0060] As for R α, from the viewpoint of providing copolymerization of the monomer of structural unit (II), it is preferably a hydrogen atom or a methyl group.

[0061] For L CA, a single bond or -COO-* is preferred.

[0062] As the protecting group represented by R 101 that is deprotected under the action of acid, those that are the same as the acid dissociative group of X 1 in the formula (1) can be listed.

[0063] Examples of alkyl groups in R 102 include: methyl, ethyl, propyl, and other straight-chain or branched alkyl groups with 1 to 8 carbon atoms. Examples of fluorinated alkyl groups include: trifluoromethyl, pentafluoroethyl, and other straight-chain or branched fluorinated alkyl groups with 1 to 8 carbon atoms. Examples of alkoxycarbonyloxy groups include: methoxycarbonyloxy, butoxycarbonyloxy, and adamantylmethoxycarbonyloxy, and other chain-like or alicyclic alkoxycarbonyloxy groups with 2 to 16 carbon atoms. Examples of acetyl groups include: acetyl, propionic, benzoyl, and acrylyl, and other aliphatic or aromatic acetyl groups with 2 to 12 carbon atoms. Examples of acetyloxy groups include: acetyloxy, propionic, benzoyloxy, and acryloxy, and other aliphatic or aromatic acetyloxy groups with 2 to 12 carbon atoms.

[0064] As n 3, it is more preferably 0 or 1, and even more preferably 0.

[0065] The value of m3 is preferably an integer from 1 to 3, and more preferably 1 or 2.

[0066] The value of m4 is preferably an integer from 0 to 3, and more preferably an integer from 0 to 2.

[0067] The structural unit (II) is preferably a structural unit represented by equations (2a-1) to (2a-10) below (hereinafter also referred to as "structural unit (2a-1) to structural unit (2a-10)").

[0068] [Chemistry 17]

[0069] In equations (2a-1) to (2a-10), Rα is the same as in equation (2).

[0070] Among these, the structural units (2a-1) to (2a-4), (2a-6), (2a-8), and (2a-9) are preferred.

[0071] The content ratio of structural unit (II) (total when multiple structural units (II) are present) relative to all structural units constituting the resin is preferably 5 mol% or more, more preferably 8 mol% or more, further preferably 10 mol% or more, and particularly preferably 15 mol% or more. The content ratio is preferably 50 mol% or less, more preferably 40 mol% or less, further preferably 35 mol% or less, and particularly preferably 30 mol% or less. By setting the content ratio of structural unit (II) within the aforementioned range, the radiosensitive linear resin composition can achieve further improvement in sensitivity and CDU performance.

[0072] When polymerizing monomers such as hydroxyl styrene that have phenolic hydroxyl groups, it is preferable to carry out the polymerization in a state where the phenolic hydroxyl groups are protected by protecting groups such as base dissociation groups, and then perform hydrolysis and deprotection to obtain structural unit (II).

[0073] (Structural Unit (III)) Structural unit (III) is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sulfonyl lactone structures. By further having structural unit (III), the solubility of the base resin in the developer can be adjusted, resulting in improved lithography properties such as resolution of the radiosensitive linear resin composition. Furthermore, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0074] As a structural unit (III), for example, the structural units represented by the following equations (T-1) to (T-10) can be listed.

[0075] [Chemistry 18]

[0076] In the formula, RL1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. RL2 to RL5 are independently hydrogen atoms, alkyl groups with 1 to 4 carbon atoms, cyano groups, trifluoromethyl groups, methoxy groups, methoxycarbonyl groups, hydroxyl groups, hydroxymethyl groups, or dimethylamino groups. RL4 and RL5 can also be divalent alicyclic groups with 3 to 8 carbon atoms bonded together with each other and forming a group. L2 is a single bond or a divalent linker. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0077] As a divalent alicyclic group with 3 to 8 carbon atoms, formed by the combination of RL4 and RL5 with the bonded carbon atoms, there is no particular limitation as long as it is formed by removing two hydrogen atoms from the same carbon atom of the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon constituting the aforementioned number of carbon atoms. It can be either a monocyclic or polycyclic hydrocarbon group. As a polycyclic hydrocarbon group, it can be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, and it can also be either a saturated or unsaturated hydrocarbon group. Furthermore, a condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed by multiple alicyclic rings sharing a common edge (the bond between two adjacent carbon atoms).

[0078] Examples of divalent linking groups represented by L2 include: divalent linear or branched hydrocarbon groups with 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups with 4 to 12 carbon atoms, or groups consisting of one or more of these hydrocarbon groups and at least one of the groups selected from -CO-, -O-, -NH- and -S-.

[0079] As structural unit (III), these are preferably structural units containing a lactone structure, more preferably structural units containing a norbornene lactone structure, and even more preferably structural units derived from norbornene lactone-based esters of (meth)acrylate.

[0080] The content ratio of structural unit (III) (total when multiple structural units (III) are present) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to all structural units constituting the base resin. The content ratio is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less. By setting the content ratio of structural unit (III) within the aforementioned range, the radiosensitive linear resin composition can further improve lithography properties such as resolution and the adhesion between the formed resist pattern and the substrate.

[0081] (Other structural units) In addition to the structural units (I) to (III) described above, the base resin may also arbitrarily have other structural units. Examples of such other structural units include structural units (IV) containing polar groups (excluding those corresponding to structural units (II) and (III)) or other structural units (V) containing acid-dissociable groups (excluding those corresponding to structural unit (I)).

[0082] (Structural Unit (IV)) The base resin further has structural units (IVs), thereby adjusting its solubility in the developer, which in turn improves the photosensitive linear resin composition's resolution and other lithography properties. Examples of polar groups include hydroxyl, carboxyl, cyano, nitro, and sulfonamide groups. Among these, hydroxyl and carboxyl groups are preferred, and hydroxyl groups are even more preferred.

[0083] As a structural unit (IV), for example, structural units represented by the following formulas can be listed.

[0084] [Chemistry 19]

[0085] In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0086] When the base resin has structural units (IVs), the lower limit of the content ratio of structural units (IVs) relative to all structural units constituting the base resin (total if multiple structural units (IVs) are present) is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%. Furthermore, the upper limit of the content ratio is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol%. By setting the content ratio of structural units (IVs) within the aforementioned range, the lithography properties such as resolution of the radiosensitive linear resin composition can be further improved.

[0087] (Structural Unit (V)) Structural unit (V) is a structural unit containing an acid-dissociable group (but different from structural unit (I) and structural unit (II)). As for structural unit (V), there is no particular limitation as long as it contains an acid-dissociable group. For example, structural units with a tertiary alkyl ester moiety, structural units with a phenolic hydroxyl group whose hydrogen atom is substituted by a tertiary alkyl group, and structural units with an acetal bond can be listed. From the viewpoint of improving the pattern-forming properties of the radiosensitive linear resin composition, the structural unit represented by the following formula (3) is preferred (hereinafter also referred to as "structural unit (V-1)").

[0088] [Chemistry 20]

[0089] In formula (3), R7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R8 is a monovalent hydrocarbon group with 1 to 20 carbon atoms. R9 and R10 are independently monovalent chain hydrocarbon groups with 1 to 10 carbon atoms or monovalent alicyclic hydrocarbon groups with 3 to 20 carbon atoms, or represent divalent alicyclic hydrocarbon groups with 3 to 20 carbon atoms formed by the combination of these groups with each other and together with the carbon atoms to which they are bonded.

[0090] As for R 7, from the viewpoint of providing copolymerization of the monomer of the structural unit (V-1), it is preferably hydrogen atom, methyl group, and more preferably methyl group.

[0091] Examples of monovalent hydrocarbon groups with 1 to 20 carbon atoms represented by R 8 include: chain hydrocarbon groups with 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups with 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups with 6 to 20 carbon atoms.

[0092] As the chain hydrocarbon groups with 1 to 10 carbon atoms represented by R 8 to R 10, examples include straight-chain or branched saturated hydrocarbon groups with 1 to 10 carbon atoms, or straight-chain or branched unsaturated hydrocarbon groups with 1 to 10 carbon atoms.

[0093] As the alicyclic hydrocarbon group with 3 to 20 carbon atoms represented by R 8 to R 10, examples include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups.

[0094] Examples of monovalent aromatic hydrocarbon groups with 6 to 20 carbon atoms represented by R 8 include: Aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthracene; aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0095] R8 is preferably a straight-chain or branched saturated hydrocarbon group with 1 to 5 carbon atoms, a straight-chain or branched unsaturated hydrocarbon group with 1 to 5 carbon atoms, an alicyclic hydrocarbon group with 3 to 12 carbon atoms, or a monovalent aromatic hydrocarbon group with 6 to 12 carbon atoms.

[0096] The groups represented by R9 and R10, when combined with each other and together with the carbon atoms they are bonded, form a divalent alicyclic group with 3 to 20 carbon atoms, which can be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group.

[0097] In these, it is preferable that R8 is an alkyl group having 1 to 4 carbon atoms, and that R9 and R10 are bonded together with each other and together with the carbon atoms bonded thereto form an alicyclic structure that is a polycyclic or monocyclic cycloalkane structure.

[0098] As a structural unit (V-1), for example, the structural units represented by the following equations (3-1) to (3-6) (hereinafter also referred to as "structural unit (V-1-1) to structural unit (V-1-6)") can be listed.

[0099] [Chemistry 21]

[0100] In equations (3-1) to (3-6), R7 to R10 have the same meaning as in equation (3). i and j are independent integers from 1 to 4. k and l are 0 or 1.

[0101] As i and j, 1 is preferred. As R 8, methyl, ethyl or isopropyl is preferred. As R 9 and R 10, methyl or ethyl is preferred.

[0102] The base resin may contain one or more structural units (V).

[0103] When the base resin contains structural units (V), the lower limit of the content ratio of structural units (V) (the total content ratio when multiple structural units are included) relative to all structural units constituting the base resin is preferably 3 mol%, more preferably 5 mol%, and even more preferably 10 mol%. Furthermore, the upper limit of the content ratio is preferably 50 mol%, more preferably 40 mol%, and even more preferably 30 mol%. By setting the content ratio of structural units (V) within the aforementioned range, the pattern-forming properties of the radiosensitive linear resin composition can be further improved.

[0104] (Methods for synthesizing resins) Resins that serve as the base resin can be synthesized, for example, by using known free radical polymerization initiators, to polymerize monomers that provide each structural unit in a suitable solvent.

[0105] The molecular weight of the resin used as the base resin is not particularly limited. However, the lower limit of the equivalent weight average molecular weight (Mw) of polystyrene obtained by gel permeation chromatography (GPC) is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 4,000. Furthermore, the upper limit of Mw is preferably 50,000, more preferably 30,000, further preferably 15,000, and particularly preferably 12,000. If the Mw of the resin is within the aforementioned range, the obtained resist film exhibits good heat resistance and developability.

[0106] The ratio (Mw / Mn) of the resin as the base resin to the equivalent number average molecular weight (Mn) of the polystyrene obtained by GPC is generally 1 or more and 5 or less, preferably 1 or more and 3 or less, and even more preferably 1 or more and 2 or less.

[0107] The methods for determining the Mw and Mn of the resin in this specification are as described in the examples.

[0108] The resin content, relative to all solid components of the radiosensitive linear resin composition, is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more.

[0109] <Other Resins> The radiosensitive linear resin composition of this embodiment may also include a resin with a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as "high fluorine content resin") as other resins. When the radiosensitive linear resin composition contains a high fluorine content resin, it may be more concentrated on the surface of the resist film relative to the base resin. As a result, the state of the resist film surface or the component distribution in the resist film can be controlled to a desired state.

[0110] As a high-fluorine content resin, it is preferable, for example, to have, as needed, structural units (I) to (V) in the base resin alone or in combination, as well as structural units represented by the following formula (6) (hereinafter also referred to as "structural unit (VI)"). [Chemistry 22]

[0111] In formula (6), R13 is a hydrogen atom, methyl or trifluoromethyl. G is a single bond, oxygen atom, sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. R14 is 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.

[0112] When the high-fluorine content resin has structural unit (VI), the lower limit of the content ratio of structural unit (VI) relative to all structural units constituting the high-fluorine content resin is preferably 50 mol%, more preferably 60 mol%, further preferably 70 mol%, and especially preferably 80 mol%. The upper limit of the content ratio is preferably 100 mol%, more preferably 98 mol%, and further preferably 95 mol%. By setting the content ratio of structural unit (VI) within the above range, the mass content of fluorine atoms in the high-fluorine content resin can be adjusted more appropriately, further promoting the biased presence on the surface of the resist film.

[0113] In addition to structural unit (VI), high-fluorine resins may also contain structural units (hereinafter also referred to as structural unit (VII)) having either (x) an alkali-soluble group or (y) a group that dissociates under the action of alkali and increases solubility in alkaline developing solutions. By having structural unit (VII) in high-fluorine resins, the increased solubility in alkaline developing solutions can suppress the generation of developing defects.

[0114] When the high-fluorine content resin has structural unit (VII), the lower limit of the content ratio of structural unit (VII) relative to all structural units constituting the high-fluorine content resin is preferably 10 mol%, more preferably 20 mol%, further preferably 30 mol%, and especially preferably 35 mol%. The upper limit of the content ratio is preferably 90 mol%, more preferably 75 mol%, and further preferably 60 mol%. By setting the content ratio of structural unit (VII) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0115] As a lower limit for the content of the high-fluorine resin, it is preferably 0.1 parts by weight, more preferably 0.5 parts by weight, and even more preferably 1 part by weight, and particularly preferably 1.5 parts by weight, relative to 100 parts by weight of the base resin. As an upper limit for the content, it is preferably 12 parts by weight, more preferably 10 parts by weight, even more preferably 8 parts by weight, and particularly preferably 5 parts by weight.

[0116] (Synthesis method of high fluorine content resin) High-fluorine content resins can be synthesized using the same method as the base resin.

[0117] <O-Salt> Onium salts comprise an organic acid anion moiety and an onium cation moiety, and are components that generate acid through exposure. By having at least a portion of the onium cation moiety in the onium salt contain an aromatic ring structure with fluorine atoms, high sensitivity and suppressive developer residue can be achieved based on improved acid generation efficiency.

[0118] The form in which the onium salt is contained in the radiosensitive linear resin composition is not particularly limited, but the onium salt is preferably at least one selected from the group consisting of: a radiosensitive linear acid generator comprising the anionic portion of the organic acid anion and the cation portion of the onium; and an acid diffusion control agent comprising the anionic portion of the organic acid anion and the cation portion of the onium, and which, upon irradiation by radiation, generates an acid with a pKa higher than that generated by the radiosensitive linear acid generator. The differences between these functions will be explained below.

[0119] The acid generated by exposing ononium salts is considered to perform two functions in the radiosensitive linear resin composition, depending on its strength. The first function includes the following: when the resin contains structural units with acid-dissociable groups, the acid generated by exposure causes the acid-dissociable groups of those structural units to dissociate and generate carboxyl groups, etc. Ononium salts with this first function are called radiosensitive linear acid generators. The second function includes the following: under the patterning conditions of the radiosensitive linear resin composition, the acid-dissociable groups of the resin are not substantially dissociated, and acid diffusion from the radiosensitive linear acid generator is suppressed in unexposed areas through salt exchange. Ononium salts with this second function are called acid diffusion control agents. The acid generated from the acid diffusion control agent is considered a relatively weaker acid (acid with a high pKa) than the acid generated from the radiosensitive linear acid generator. Whether onium salts function as radiosensitive linear acid generators or as acid diffusion control agents depends on the energy required for the dissociation of the acid-dissociating groups in the resin and the acidity of the onium salt. The preferred form for radiosensitive linear acid generators in radiosensitive linear resin compositions is the onium salt structure existing alone as a (low molecular weight) compound.

[0120] By including the radiosensitive linear resin composition containing the radiosensitive linear acid generator, the polarity of the resin in the exposure section increases. When the resin in the exposure section is developed in an alkaline aqueous solution, it becomes soluble in the developer. On the other hand, when it is developed in an organic solvent, it becomes insoluble in the developer.

[0121] In addition, by containing the acid diffusion control agent, the radiosensitive linear resin composition can suppress the diffusion of acid in the unexposed area, and can form a resist pattern with better pattern developability and CDU performance.

[0122] In the radiosensitive linear resin composition, preferably at least one of the organic acid anion portion of the radiosensitive linear acid generator and the organic acid anion portion of the acid diffusion control agent contains an iodine-substituted aromatic ring structure. Iodine atoms have very high absorption of EUV and other radiation at a wavelength of 13.5 nm, thereby achieving high sensitivity. Furthermore, if the organic acid anion portion of the onium salt contains an iodine-substituted aromatic ring structure, the large molecular weight of its iodine atoms can be used to control acid diffusion, thereby improving CDU performance. When the organic acid anion portion of the onium salt contains an iodine-substituted aromatic ring structure, the iodine-substituted aromatic ring structure and the aromatic ring structure containing fluorine atoms can exist in the same compound or in different compounds.

[0123] Regardless of the form in which the onium salt is contained, the organic acid anion moiety is preferably at least one selected from the group consisting of sulfonate anions, carboxylate anions, and sulfadiazine anions. Furthermore, the onium cation is preferably at least one selected from the group consisting of strontium cations and monium cations. By combining these structures, the onium salt can efficiently exert the aforementioned functions.

[0124] As acids produced by exposure, corresponding to the organic acid anions mentioned above, examples that produce sulfonic acid, carboxylic acid, and sulfadiene by exposure can be listed.

[0125] For example, examples of onium salts that provide sulfonic acid through exposure include: (1) A compound having one or more fluorine atoms or fluorinated hydrocarbon groups bonded to a carbon atom adjacent to a sulfonate anion. (2) A compound in which neither a fluorine atom nor a fluorinated hydrocarbon group is bonded to a carbon atom adjacent to a sulfonate anion.

[0126] Examples of onium salts that provide carboxylic acids through exposure include: (3) Compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are bonded to the carbon atom adjacent to the carboxylate anion. (4) A compound in which a fluorine atom or a fluorinated hydrocarbon group is not bonded to a carbon atom adjacent to a carboxylate anion.

[0127] Of these, the one corresponding to (1) is preferred as the radiosensitive linear acid generator. The one corresponding to (2), (3) or (4) is preferred as the acid diffusion control agent, and the one corresponding to (2) or (4) is particularly preferred.

[0128] <Radiosensitive linear acid generator> Onium salts used as radiosensitive linear acid generators comprise an organic acid anion moiety and an onium cation moiety. The radiosensitive linear acid generator is preferably represented by either formula (A-1) or formula (A-2).

[0129] [Chemistry 23]

[0130] In formulas (A-1) and (A-2), L1 is a single bond, an ether bond, or an ester bond, or an alkyl group having 1 to 6 carbon atoms that may contain an ether bond or an ester bond. The alkyl group may be any of the following: linear, branched, or cyclic.

[0131] R1 is a hydroxyl, carboxyl, fluorine, chlorine, bromine, or amino group; or it may be an alkyl group with 1 to 20 carbon atoms that contains a fluorine, chlorine, bromine, hydroxyl, amino, or an alkoxy group with 1 to 10 carbon atoms, an alkoxy group with 1 to 20 carbon atoms, an alkoxy carbonyl group with 2 to 10 carbon atoms, an acetoxy group with 2 to 20 carbon atoms, or an alkyl sulfonyloxy group with 1 to 20 carbon atoms; or -NR 8-C(=O)-R 9 or -NR 8-C(=O)-OR 9, where R8 is a hydrogen atom or may contain a halogen atom, a hydroxyl, an alkoxy group with 1 to 6 carbon atoms, an acetoxy group with 2 to 6 carbon atoms, or an alkyl group with 2 to 6 carbon atoms. 9 is an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and may contain a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, a cellulose group having 2 to 6 carbon atoms, or a cellulose oxy group having 2 to 6 carbon atoms. The alkyl group, alkoxy group, alkoxycarbonyl group, cellulose oxy group, cellulose group, and alkenyl group may be any of the following: linear, branched, or cyclic.

[0132] Among these, R1 is preferably a hydroxyl group, -NR8-C(=O)-R9, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, etc.

[0133] When p is 1, R2 is a single bond or a divalent linker with 1 to 20 carbon atoms. When p is 2 or 3, R2 is a trivalent or tetravalent linker with 1 to 20 carbon atoms. This linker may contain oxygen, sulfur or nitrogen atoms.

[0134] Rf1 through Rf4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one of them is a fluorine atom or a trifluoromethyl group. Additionally, Rf1 and Rf2 can combine to form a carbonyl group. Particularly preferred are Rf3 and Rf4 both fluorine atoms.

[0135] R3, R4, R5, R6, and R7 are each independently a monovalent hydrocarbon group with 1 to 20 carbon atoms, which may contain heteroatoms. R3, R4, and R5 contain one or more fluorine atoms, and R6 and R7 contain one or more fluorine atoms. Furthermore, any two of R3, R4, and R5 may bond to each other and form a ring together with the bonded sulfur atoms. The monovalent hydrocarbon group may be linear, branched, or cyclic; specific examples include alkyl groups with 1 to 12 carbon atoms, alkenyl groups with 2 to 12 carbon atoms, alkynyl groups with 2 to 12 carbon atoms, aryl groups with 6 to 20 carbon atoms, and aralkyl groups with 7 to 12 carbon atoms. In addition, some or all of the hydrogen atoms of these groups may be substituted with hydroxyl, carboxyl, halogen, cyano, amide, nitro, mercapto, sulopentalide, sulfonyl, or strontium salt-containing groups, and some of the carbon atoms of these groups may be substituted with ether, ester, carbonyl, carbonate, or sulfonate bonds.

[0136] p is an integer satisfying 1 ≤ p ≤ 3. q and r are integers satisfying 0 ≤ q ≤ 5, 0 ≤ r ≤ 3, and 0 ≤ q + r ≤ 5. q is preferably an integer satisfying 1 ≤ q ≤ 3, more preferably 2 or 3. r is preferably an integer satisfying 0 ≤ r ≤ 2.

[0137] Examples of organic acid anionic moieties representing the radiosensitive linear acid generators represented by formulas (A-1) and (A-2) are listed below, but are not limited to these. Furthermore, the following examples all describe organic acid anionic moieties having an iodine-substituted aromatic ring structures. However, for organic acid anionic moieties not having an iodine-substituted aromatic ring structures, structures formed by substituting the iodine atom in the following formulas with atoms or groups other than iodine atoms, such as hydrogen atoms or other substituents, are preferred.

[0138] [Chemistry 24]

[0139] [Chemistry 25]

[0140] [Chemistry 26]

[0141] [Chemistry 27]

[0142] [Chemistry 28]

[0143] [Chemistry 29]

[0144] [Chemistry 30]

[0145] [Chemistry 31]

[0146] [Chemistry 32]

[0147] [Chemistry 33]

[0148] [Chemistry 34]

[0149] [Chemistry 35]

[0150] [Chemistry 36]

[0151] [Chemistry 37]

[0152] The onium cation portion of the radiosensitive acid generator represented by formula (A-1) is preferably represented by the following formula (Q-1).

[0153] [Chemistry 38]

[0154] In formula (Q-1), Ra1 and Ra2 each independently represent a substituent. n1 represents an integer from 0 to 5. When n1 is 2 or more, there can be multiple Ra1s that are the same or different. n2 represents an integer from 0 to 5. When n2 is 2 or more, there can be multiple Ra2s that are the same or different. n3 represents an integer from 0 to 5. When n3 is 2 or more, there can be multiple Ra3s that are the same or different. Ra3 represents a fluorine atom or a group having one or more fluorine atoms. Ra1 and Ra2 can also be linked together to form a ring. When n1 is 2 or more, multiple Ra1s can also be linked together to form a ring. When n2 is 2 or more, multiple Ra2s can also be linked together to form a ring.

[0155] The substituents represented by Ra1 and Ra2 are preferably alkyl, cycloalkyl, alkoxy, cycloalkyloxy, alkoxycarbonyl, alkylsulfonyl, hydroxyl, halogen atom, or halogenated hydrocarbon group.

[0156] The alkyl groups of Ra1 and Ra2 can be straight-chain alkyl groups or branched alkyl groups. Preferably, the alkyl group has 1 to 10 carbon atoms, and more preferably methyl, ethyl, n-butyl, and tributyl.

[0157] As cycloalkyl groups of Ra1 and Ra2, examples include monocyclic or polycyclic cycloalkyl groups (preferably cycloalkyl groups with 3 to 20 carbon atoms). Among these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl are particularly preferred.

[0158] The alkyl portion of the alkoxy group in Ra1 and Ra2 can be exemplified by those previously listed as alkyl groups in Ra1 and Ra2. Preferably, the alkoxy group is methoxy, ethoxy, n-propoxy, or n-butoxy.

[0159] The cycloalkyl moiety of Ra1 and Ra2 can be exemplified by those previously listed as cycloalkyl groups of Ra1 and Ra2. Cyclopentyloxy and cyclohexyloxy are particularly preferred as the cycloalkyloxy group.

[0160] The alkoxy moiety of the alkoxycarbonyl group in Ra1 and Ra2 can be exemplified by those previously listed as alkoxy groups in Ra1 and Ra2. Preferably, the alkoxycarbonyl group is methoxycarbonyl, ethoxycarbonyl, or n-butoxycarbonyl.

[0161] The alkyl portion of the alkyl sulfonyl group in Ra1 and Ra2 can be exemplified by those previously listed as alkyl groups in Ra1 and Ra2. Similarly, the cycloalkyl portion of the cycloalkyl sulfonyl group in Ra1 and Ra2 can be exemplified by those previously listed as cycloalkyl groups in Ra1 and Ra2. Preferably, these alkyl sulfonyl or cycloalkyl sulfonyl groups are methanesulfonyl, ethanesulfonyl, n-propanesulfonyl, n-butanesulfonyl, cyclopentanesulfonyl, and cyclohexanesulfonyl.

[0162] Each group of Ra1 and Ra2 may also have substituents. Examples of such substituents include: halogen atoms such as fluorine atoms (preferably fluorine atoms), hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxy groups, cycloalkyloxy groups, alkoxyalkyl groups, cycloalkyloxyalkyl groups, alkoxycarbonyl groups, cycloalkyloxycarbonyl groups, alkoxycarbonyloxy groups, and cycloalkyloxycarbonyloxy groups.

[0163] Halogen atoms that can be used as Ra1 and Ra2 include fluorine, chlorine, bromine, and iodine atoms, with fluorine atoms being the most preferred.

[0164] The halogenated hydrocarbon groups of Ra1 and Ra2 are preferably alkyl halogenated groups. Examples of alkyl groups and halogen atoms constituting alkyl halogenated groups are the same as those described above. Among these, fluorinated alkyl groups are preferred, and CF3 is even more preferred.

[0165] As described above, Ra1 and Ra2 can also be linked together to form a ring (i.e., a heterocycle containing sulfur atoms). In this case, Ra1 and Ra2 preferably form a single bond or a divalent linker. Examples of divalent linkers include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO2-, alkylene, cycloalkylene, alkenylene, or combinations of two or more of these, preferably with a total carbon number of 20 or less. Furthermore, when n1 is 2 or more, multiple Ra1s can be linked together to form a ring, and when n2 is 2 or more, multiple Ra2s can be linked together to form a ring. For example, two Ra1s linked together and together with the bonded benzene rings can form a naphthalene ring.

[0166] Ra3 is a fluorine atom or a group having a fluorine atom. Examples of groups having a fluorine atom include alkyl, cycloalkyl, alkoxy, cycloalkyloxy, alkoxycarbonyl, and alkylsulfonyl groups substituted with a fluorine atom in Ra1 and Ra2. Fluorinated alkyl groups are preferred examples, and more preferably, CF3, C2F5, C3F7, C4F9, C5F11, C6F13, C7F15, C8F17, CH2CF3, CH2CH2CF3, CH2C2F5, CH2CH2C2F5, CH2C3F7, CH2CH2C3F7, CH2C4F9, and CH2CH2C4F9 are also preferred. CF3 is particularly preferred.

[0167] Ra3 is preferably a fluorine atom or CF3, and more preferably a fluorine atom.

[0168] n1 and n2 are each preferably independent integers from 0 to 3, and more preferably integers from 0 to 2.

[0169] n3 is preferably an integer from 1 to 3, and even more preferably 1 or 2.

[0170] (n1+n2+n3) is preferably an integer from 1 to 15, more preferably an integer from 1 to 9, further preferably an integer from 2 to 6, and especially preferably an integer from 3 to 6. When (n1+n2+n3) is 1, it is preferable that n3=1 and Ra3 is a fluorine atom or CF3. When (n1+n2+n3) is 2, it is preferable that n1=n3=1 and Ra1 and Ra3 are each independently a fluorine atom or CF3 combination, and that n3=2 and Ra3 is a fluorine atom or CF3 combination. When (n1+n2+n3) is 3, it is preferable that n1=n2=n3=1 and Ra1~Ra3 are each independently a fluorine atom or CF3 combination.

[0171] As a specific example of the onium cation moiety represented by the aforementioned formula (Q-1), the following examples can be cited. Furthermore, the following examples all contain an aromatic ring structure having a fluorine atom, but as an onium cation moiety that does not contain an aromatic ring structure having a fluorine atom, it is preferable to adopt a structure obtained by substituting the fluorine atom or CF3 in the following formula with atoms or groups other than fluorine atoms such as hydrogen atoms or other substituents.

[0172] [Chemistry 39]

[0173] [Chemistry 40]

[0174] [Chemistry 41]

[0175] In the case where the onium cation moiety in the radiosensitive linear acid generator represented by formula (A-2) contains an aromatic ring structure having a fluorine atom, the onium cation moiety is preferably a diaryl-monylonium cation having one or more fluorine atoms.

[0176] Specific examples of such onium cation moieties can be given below. Furthermore, the following are all onium cation moieties containing an aromatic ring structure with fluorine atoms. However, as onium cation moieties that do not contain an aromatic ring structure with fluorine atoms, it is preferable to adopt a structure in which the fluorine atom or CF3 in the following formula is substituted with atoms or groups other than fluorine atoms, such as hydrogen atoms or other substituents.

[0177] [Chemistry 42]

[0178] Regarding the synthesis methods of the radiosensitive linear acid generators represented by formulas (A-1) and (A-2), they can also be synthesized by known methods, particularly salt exchange reactions. Known radiosensitive linear acid generators can also be used as long as the effects of the present invention are not compromised.

[0179] These radiosensitive linear acid generators can be used alone or in combination of two or more. The lower limit of the content of the radiosensitive linear acid generator relative to 100 parts by weight of the base resin is preferably 0.5 parts by weight, more preferably 1 part by weight, further preferably 2 parts by weight, and particularly preferably 4 parts by weight. Furthermore, the upper limit of the content is preferably 20 parts by weight, more preferably 18 parts by weight, further preferably 15 parts by weight, and particularly preferably 12 parts by weight. This allows for excellent sensitivity or CDU performance when forming resist patterns.

[0180] <Acid diffusion control agent> The onium salt used as an acid diffusion control agent comprises an organic acid anion moiety and an onium cation moiety, and generates an acid with a higher pKa than that generated by the radiosensitive linear acid generator upon irradiation. The acid diffusion control agent is preferably represented by the following formula (S-1) or the following formula (S-2).

[0181] [Chemistry 43]

[0182] In formulas (S-1) and (S-2), R1 is a hydrogen atom, hydroxyl group, fluorine atom, chlorine atom, amino group, nitro group, or cyano group; it may be an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, an acetoxy group with 2 to 6 carbon atoms, or an alkyl sulfonyloxy group with 1 to 4 carbon atoms, which may be substituted with a halogen atom; or -NR1A-C(=O)-R1B or -NR1A-C(=O)-OR1B. R1A is a hydrogen atom or an alkyl group with 1 to 6 carbon atoms, and R1B is an alkyl group with 1 to 6 carbon atoms or an alkenyl group with 2 to 8 carbon atoms.

[0183] R3, R4, R5, R6, and R7 are each independently a monovalent hydrocarbon group with 1 to 20 carbon atoms, which may contain heteroatoms. R3, R4, and R5 are preferably monovalent hydrocarbon groups containing one or more fluorine atoms or groups having fluorine atoms, and R6 and R7 are preferably monovalent hydrocarbon groups containing one or more fluorine atoms or groups having fluorine atoms. Furthermore, any two of R3, R4, and R5 may be bonded to each other and form a ring together with the bonded sulfur atoms. The monovalent hydrocarbon group may be linear, branched, or cyclic; specific examples include alkyl groups with 1 to 12 carbon atoms, alkenyl groups with 2 to 12 carbon atoms, alkynyl groups with 2 to 12 carbon atoms, aryl groups with 6 to 20 carbon atoms, and aralkyl groups with 7 to 12 carbon atoms. Additionally, some or all of the hydrogen atoms in these groups may be substituted with substituents.

[0184] L1 is a single bond or a divalent linker with 1 to 20 carbon atoms, and may also include ether bonds, carbonyl groups, ester bonds, amide bonds, sulopentalide rings, endamide rings, carbonate bonds, halogen atoms, hydroxyl groups, or carboxyl groups.

[0185] m and n are integers that satisfy 0≦m≦5, 0≦n≦3, and 0≦m+n≦5, but preferably integers that satisfy 1≦m≦3 and 0≦n≦2.

[0186] Examples of anions that serve as acid diffusion control agents represented by formula (S-1) or (S-2) are listed below, but are not limited to these. Furthermore, the following examples are all anionic moieties of organic acid radicals having an iodine-substituted aromatic ring structures. However, for anionic moieties of organic acid radicals without an iodine-substituted aromatic ring structures, structures formed by substituting the iodine atom in the following formulas with atoms or groups other than iodine atoms, such as hydrogen atoms or other substituents, are preferred.

[0187] [Chemistry 44]

[0188] [Chemistry 45]

[0189] [Chemistry 46]

[0190] [Chemistry 47]

[0191] [Chemistry 48]

[0192] The onium cation portion of the acid diffusion control agent represented by formulas (S-1) and (S-2) can preferably be the onium cation portion of a radiosensitive linear acid generator.

[0193] The acid diffusion control agents represented by formulas (S-1) and (S-2) can also be synthesized by known methods, particularly salt exchange reactions. Known acid diffusion control agents can also be used as long as the effects of the present invention are not compromised. Furthermore, the case where the anionic moiety of the organic acid radical and the onium cation moiety share the same aromatic ring structure is also included in the acid diffusion control agents of this embodiment.

[0194] These acid diffusion control agents can be used alone or in combination of two or more. The lower limit of the acid diffusion control agent content relative to 100 parts by weight of the base resin is preferably 0.5 parts by weight, more preferably 1 part by weight, and even more preferably 1.5 parts by weight. Furthermore, the upper limit of the content is preferably 15 parts by weight, more preferably 12 parts by weight, and even more preferably 8 parts by weight. This allows for excellent sensitivity or CDU performance when forming resist patterns.

[0195] (Structure of the anionic portion of other organic acid radicals (1)) The radiosensitive linear acid generator (including both radiosensitive linear strong acid generator and acid diffusion control agent) may also include, or replace, the structure represented by the following formula (bd1) as the organic acid anion portion of the radiosensitive linear strong acid generator represented by formulas (A-1) and (A-2) or the organic acid anion portion of the acid diffusion control agent represented by formulas (S-1) and (S-2).

[0196] [Chemistry 49]

[0197] In the formula (bd1), R x1 to R x4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of two or more of these. Ry1 to Ry2 can be independently hydrogen atoms, substituted or unsubstituted hydrocarbon groups, or represent ring structures formed by their combination. [Transformation 50] It can be a double bond or a single bond. R z1 to R z4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of two or more of these. However, at least one of R x1 to R x4, R y1 to R y2 and R z1 to R z4 has an acid radical anion structure.

[0198] The hydrocarbon groups in Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 can be aliphatic hydrocarbon groups or aromatic hydrocarbon groups, and can be cyclic hydrocarbon groups or chain hydrocarbon groups. For example, examples of substituent hydrocarbon groups among Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 include: cyclic groups that may have substituents, chain alkyl groups that may have substituents, or chain alkenyl groups that may have substituents.

[0199] The cyclic group that may have substituents is preferably a cyclic hydrocarbon group, which can be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. An aliphatic hydrocarbon group refers to a hydrocarbon group that is not aromatic. Furthermore, the aliphatic hydrocarbon group can be saturated or unsaturated, but is generally preferred to be saturated. Additionally, the cyclic hydrocarbon groups in Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 may also contain heteroatoms, similar to heterocycles.

[0200] The aromatic hydrocarbon groups in Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 are hydrocarbon groups having an aromatic ring. The number of carbon atoms in this aromatic hydrocarbon group is preferably 3~30, more preferably 5~30, further preferably 5~20, particularly preferably 6~15, and most preferably 6~12. Herein, the number of carbon atoms is set excluding the carbon atoms in the substituents.

[0201] Aromatic rings, which are the aromatic hydrocarbon groups in Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4, can be specifically listed as: benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, or aromatic heterocycles in which a portion of the carbon atom constituting these aromatic rings is substituted by a heteroatom.

[0202] As aromatic hydrocarbon groups in Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4, specifically, groups obtained by removing one hydrogen atom from the aromatic ring can be listed.

[0203] Cyclic aliphatic hydrocarbon groups in Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 can be listed as aliphatic hydrocarbon groups containing rings in their structures. Examples of aliphatic hydrocarbon groups containing rings in such structures include: alicyclic hydrocarbon groups (groups formed by removing one hydrogen atom from an aliphatic hydrocarbon ring), alicyclic hydrocarbon groups bonded to the end of a straight-chain or branched aliphatic hydrocarbon group, and alicyclic hydrocarbon groups interposed in the middle of a straight-chain or branched aliphatic hydrocarbon group.

[0204] The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.

[0205] The alicyclic hydrocarbon group can be a polycyclic group or a monocyclic group.

[0206] Among them, the cyclic aliphatic hydrocarbon groups in Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 are preferably groups obtained by removing one or more hydrogen atoms from monocyclic alkanes or polycyclic alkanes.

[0207] The linear aliphatic hydrocarbon group that can bond with an alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

[0208] The branched aliphatic hydrocarbon group that can bond with an alicyclic hydrocarbon group preferably has 2 to 10 carbons, more preferably 3 to 6 carbons, and even more preferably 3 or 4 carbons, with the most preferably 3 carbons.

[0209] Substituents in the cyclic groups of Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 can be, for example, alkyl, alkoxy, halogen atom, alkyl halide, hydroxyl, nitro, carbonyl, etc.

[0210] As a chain alkyl group of Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4, it can be either straight-chain or branched.

[0211] As a straight-chain alkyl group, the number of carbon atoms is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10.

[0212] As a branched alkyl group, the number of carbon atoms is preferably 3 to 20, more preferably 3 to 15, and most preferably 3 to 10.

[0213] As chain alkenyl groups of Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4, they can be either straight-chain or branched, preferably with 2~10 carbons, more preferably with 2~5 carbons, even more preferably with 2~4 carbons, and especially preferably with 3 carbons.

[0214] Substituents in the chain alkyl or chain alkenyl groups of Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 can be, for example, alkoxy groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), halogenated alkyl groups, hydroxyl groups, carbonyl groups, nitro groups, amino groups, cyclic groups in said Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4, etc.

[0215] As the hydrocarbon group among Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4, the hydrocarbon group is preferably a cyclic group that may have substituents or a chain alkyl group that may have substituents.

[0216] In formula (bd1), Ry1 to Ry2 can also bond together to form a ring structure. This ring structure can be an alicyclic hydrocarbon or an aromatic hydrocarbon. In addition, this ring structure can also be a polycyclic structure that includes other ring structures.

[0217] The alicyclic hydrocarbons formed by Ry1 to Ry2 can be polycyclic or monocyclic. Monocyclic alicyclic hydrocarbons are preferably monocyclic alkanes. Polycyclic alicyclic hydrocarbons are preferably polycyclic alkanes.

[0218] Aromatic hydrocarbon rings formed by Ry1~Ry2 can be listed as: benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, or aromatic heterocycles in which a portion of the carbon atom constituting these aromatic rings is replaced by a heteroatom.

[0219] The ring structures formed by Ry1~Ry2 (alicyclic hydrocarbons, aromatic hydrocarbons) may also have substituents. Substituents mentioned here can be the same as those in the ring structures of Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4.

[0220] In terms of the short diffusion of acid produced by exposure and the diffusion control of acid, the ring structure formed by Ry1~Ry2 is preferably an aromatic hydrocarbon that can have substituents.

[0221] In formula (bd1), two or more of R z1 to R z4 can bond together to form a ring structure. For example, R z1 can also form a ring structure together with any of R z2 to R z4. The ring structure can be an alicyclic hydrocarbon or an aromatic hydrocarbon.

[0222] The alicyclic hydrocarbons formed by two or more of R z1 to R z4 can be polycyclic or monocyclic. Monocyclic alicyclic hydrocarbons are preferably monocyclic alkanes. Polycyclic alicyclic hydrocarbons are preferably polycyclic alkanes.

[0223] Examples of aromatic hydrocarbon rings formed from two or more of R z1 to R z4 include: benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, or aromatic heterocycles in which a portion of the carbon atom constituting these aromatic rings is substituted with a heteroatom.

[0224] The ring structures formed by R z1 to R z4 (alicyclic hydrocarbons and aromatic hydrocarbons) can also have substituents.

[0225] In formula (bd1), two or more of Rx1 to Rx4 can bond together to form a ring structure. For example, Rx1 can also form a ring structure together with any of Rx2 to Rx4. The ring structure can be an alicyclic hydrocarbon or an aromatic hydrocarbon.

[0226] The alicyclic hydrocarbons formed by two or more of R x1 to R x4 can be polycyclic or monocyclic. As monocyclic alicyclic hydrocarbons, monocyclic alkanes are preferred. As polycyclic alicyclic hydrocarbons, polycyclic alkanes are preferred.

[0227] Examples of aromatic hydrocarbon rings formed from two or more of R x1 to R x4 include: benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, or aromatic heterocycles in which a portion of the carbon atom constituting these aromatic rings is substituted with a heteroatom.

[0228] The ring structures formed by R x1 to R x4 (alicyclic hydrocarbons and aromatic hydrocarbons) can also have substituents.

[0229] In terms of the diffusion control of the acid, the two or more ring structures formed by Rx1 to Rx4 are preferably alicyclic hydrocarbons.

[0230] In formula (bd1), at least one of Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 has an acid radical anion structure, and the organic acid radical anion portion is an n-valent anion. n is an integer greater than or equal to 1. The organic acid radical anion portion represented by formula (bd1) functions as a radiosensitive linear strong acid generator or an acid diffusion control agent in the composition by selecting the intramolecular acid radical anion structure. The radiosensitive linear strong acid generator generates an acid that acts on the acid dissociation groups in the base resin, and the acid diffusion control agent captures the acid generated by the radiosensitive linear strong acid generator through exposure (controlling acid diffusion).

[0231] Examples of anion structures for Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 include those with sulfonate anion structures, carboxylate anion structures, amide anion structures, methylide anion structures, carboate anion structures, borate anion structures, halide anion structures, phosphate anion structures, antimonyate anion structures, and arsenate anion structures. Among these, those with sulfonate anion structures and those with carboxylate anion structures are preferred.

[0232] In the organic acid anion portion represented by formula (bd1), Rx1~Rx4, Ry1~Ry2, and Rz1~Rz4 can also be the respective acid anion structures. When two or more of Rx1~Rx4 are bonded together to form a ring structure, the carbon atom forming the ring structure or the hydrogen atom bonded to that carbon atom can be substituted by the acid anion structure. The same applies to Ry1~Ry2 and Rz1~Rz4.

[0233] Specific examples of the anionic portion of the organic acid radical represented by the formula (bd1) are shown below, but are not limited to these.

[0234] [Chemistry 51]

[0235] [Chemistry 52]

[0236] (Structure of the anionic portion of other organic acid radicals (2)) In addition to the structures of the other organic acid anion moieties (1), the structures represented by the following formula (b1) can also be listed as other organic acid anion moieties. [Chemistry 53] (in the above formula (b1),) Rb1 is a monovalent hydrocarbon group with 17 to 50 carbon atoms that has a steroid skeleton. Yb1 is a divalent linker or single bond containing heteroatoms. V b1 is an enyl group, a fluorinated enyl group, or a single bond. Rfa and Rfb are each independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 5 carbon atoms. Zb1 has an anionic structure.

[0237] In formula (b1), Rb1 represents a monovalent hydrocarbon group having 17 to 50 carbon atoms in a steroid skeleton. The steroid skeleton may have substituents. Here, the so-called "steroid skeleton" refers to a ring structure with the following chemical formula (St) formed by the condensation of three six-membered rings and one five-membered ring.

[0238] [Chemistry 54]

[0239] In the formula (St), the number adjacent to a carbon atom indicates the carbon number. In this specification, when referring to the position of a carbon atom in the steroid skeleton, the carbon number shown in the formula (St) is used.

[0240] The steroid skeleton of the monovalent hydrocarbon group in Rb1 preferably has at least one hydroxyl group. That is, the steroid skeleton of Rb1 preferably has at least one hydrogen atom in the ring structure represented by formula (St) substituted with a hydroxyl group.

[0241] When the steroid skeleton has hydroxyl groups, the number of hydroxyl groups is not particularly limited, and examples include 1 to 10, 1 to 5, or 1 to 3. The number of hydroxyl groups is preferably 1 to 3, more preferably 2 or 3, and even more preferably 3.

[0242] The steroid skeleton of Rb1 may also contain substituents other than hydroxyl groups. For example, in the ring structure represented by the chemical formula (St), alkyl, carboxyl, lateral oxygen (=O), alkoxy, alkyl carbonyloxy, formyloxy (HC(=O)-O-), lactone-containing cyclic groups, etc., may be bonded as substituents.

[0243] When the steroid skeleton in Rb1 has an alkyl group as a substituent, the position of the alkyl group is not particularly limited, for example: 10, 13, 17, etc. The alkyl group is preferably located at the 10 and 13 positions.

[0244] When the steroid skeleton in Rb1 has substituents other than alkyl and hydroxyl groups, the position of the substituent is not particularly limited; for example, any position among 3, 7, and 12 can be listed. For example, the substituent can be present at any one or two of the 3, 7, and 12 positions. In addition, when the substituent is a cyclic group containing a lactone, it can also be at the 17 position.

[0245] The carbon number of Rb1 is 17 to 50, preferably 17 to 40, more preferably 17 to 30, and especially preferably 17 to 22. Furthermore, the number of carbon atoms in Rb1 here includes the carbon atoms that constitute the steroid skeleton, and is also assumed to include carbon atoms in the substituents that are bonded to the steroid skeleton.

[0246] Rb1 is preferably represented by the bases (Rb1-1) to (Rb1-3) below. Furthermore, in the presence of enantiomers or diastereomers, the following formulas represent stereoisomers of these, and are assumed to include these stereoisomers.

[0247] [Chemistry 55]

[0248] [In formula (Rb1-1), RS11, RS12, and RS13 independently represent substituents other than hydrogen atoms, hydroxyl groups, or hydroxyl groups containing heteroatoms. In formula (Rb1-2), RS21 and RS22 independently represent substituents other than hydrogen atoms, hydroxyl groups, or hydroxyl groups containing heteroatoms. RS23 represents an alkyl group that may contain heteroatoms. In formula (Rb1-3), RS31, RS32, and RS33 independently represent substituents other than hydrogen atoms, hydroxyl groups, or hydroxyl groups containing heteroatoms. RS34 represents a cyclic group containing lactones. * indicates a bonding bond with Yb1 in formula (b1).]

[0249] In formula (Rb1-1), substituents other than the hydroxyl groups containing heteroatoms in RS11 to RS13 can include carboxyl groups, side oxygen groups (=O), alkoxy groups, alkyl carbonyloxy groups, and formyloxy groups (HC(=O)-O-). Similarly, in formula (Rb1-2), the same applies to substituents other than the hydroxyl groups containing heteroatoms in RS21 and RS22. Furthermore, in formula (Rb1-3), the same applies to substituents other than the hydroxyl groups containing heteroatoms in RS31 to RS33.

[0250] In formula (Rb1-1), at least one of RS11 to RS13 is preferably a hydroxyl group, and more preferably any two or more of RS11 to RS13 are hydroxyl groups, and even more preferably all of RS11 to RS13 are hydroxyl groups. Among RS11 to RS13, the non-hydroxyl group is preferably a hydrogen atom.

[0251] In formula (Rb1-2), at least one of RS21 and RS22 is preferably a hydroxyl group, and preferably both RS21 and RS22 are hydroxyl groups. Among RS21 and RS22, the non-hydroxyl group is preferably a hydrogen atom. In formula (Rb1-2), RS23 represents an alkyl group that may contain heteroatoms. This alkyl group may be straight-chain or branched. Preferably, it is an alkyl group having 1 to 10 carbon atoms.

[0252] In the formula (Rb1-3), at least one of RS31 to RS33 is preferably a hydroxyl group, and more preferably any two or more of RS31 to RS33 are hydroxyl groups, and even more preferably all of RS31 to RS33 are hydroxyl groups. Among RS31 to RS33, the non-hydroxyl group is preferably a hydrogen atom.

[0253] Among them, Rb1 is preferably the basis represented by equation (Rb1-1).

[0254] The following examples of R b1 are shown, but are not limited to these. In the following formulas, * denotes the bond with Y b1 in formula (b1).

[0255] [Chemistry 56]

[0256] [Chemistry 57]

[0257] [Chem.58]

[0258] In the above, Rb1 is preferably Equation (Rb-1-1) to Equation (Rb-1-19), and more preferably Equation (Rb-1-1) to Equation (Rb-1-7).

[0259] In formula (b1), Rfa and Rfb are independently hydrogen atoms, fluorine atoms, or fluorinated alkyl groups having 1 to 5 carbon atoms.

[0260] In the formula (b1), Yb1 represents a divalent linker or single bond containing heteroatoms. As a heteroatom-containing divalent linker in Yb1, the same bases as those listed in the heteroatom-containing divalent linkers of Y1 in formula (1) can be enumerated.

[0261] Yb1 is preferably a divalent linker containing an ester or ether bond.

[0262] In the formula (b1), V b1 represents an enyl group, a fluorinated enyl group, or a single bond. The alkyl or fluorinated alkyl group in V b1 can be linear or branched, but is preferably linear. The alkyl or fluorinated alkyl group in V b1 preferably has 1 to 4 carbon atoms, and more preferably 1 to 3 carbon atoms.

[0263] The anion structure represented by Zb1 can preferably be the anion structure of Rx1~Rx4, Ry1~Ry2 and Rz1~Rz4 in the formula (bd1).

[0264] The following are specific examples of the organic acid anion portion represented by formula (b1), but are not limited to these specific examples. In the formula, k and k' independently represent integers from 0 to 5, and k'' represents integers from 1 to 5. Furthermore, the following examples all represent organic acid anion portions having sulfonate anions, but it is also preferable to use structures formed by replacing sulfonate anions with carboxylate anions. When the organic acid anion portion has carboxylate anions, the fluorine atom may not be bonded to the carbon atoms at the α- and β-positions of the carboxylate anion.

[0265] [Chemistry 59]

[0266] [Transformation 60]

[0267] [Chemistry 61]

[0268] [Chemistry 62]

[0269] The organic acid anion moiety represented by formula (b1) is preferably represented by the following formula (b1-an1). Furthermore, the following describes an organic acid anion moiety having a sulfonate anion, but a structure obtained by replacing the sulfonate anion with a carboxylate anion is also preferable. When the organic acid anion moiety has a carboxylate anion, the fluorine atom may not be bonded to the carbon atoms at the α and β positions of the carboxylate anion.

[0270] [Chemistry 63] [In the formula, RS11~RS13 are the same as RS11~RS13 in the general formula (Rb1-1). Vb11 represents a single bond, -CHF-, or -CF2-. k represents an integer from 1 to 5.]

[0271] In the formula (b1-an1), RS11~RS13 are the same as RS11~RS13 in the general formula (R b1-1).

[0272] Solvent The radiosensitive linear resin composition of this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least one of the onium salt and the base resin (radiosensitive linear acid generating resin and resin), as well as additives as needed.

[0273] Examples of solvents include: alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents.

[0274] Examples of alcohol-based solvents include: Monool solvents with 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; Polyol solvents with 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Polyol partial ether solvents, etc., are formed by etherifying a portion of the hydroxyl groups in the polyol solvent.

[0275] Examples of ether-based solvents include: Dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; Tetrahydrofuran, tetrahydropyran, and other cyclic ether solvents; Ether solvents containing aromatic rings, such as diphenyl ether and anisole (methyl phenyl ether); Polyol ether solvents, etc., are formed by etherifying the hydroxyl groups of the polyol solvent.

[0276] Examples of ketone solvents include: acetone, butanone, methyl isobutyl ketone, and other chain-like ketone solvents. Cyclopentanone, cyclohexanone, methylcyclohexanone, and other cyclic ketone solvents; 2,4-Pentanedione, acetone-acetone, acetophenone, etc.

[0277] Examples of amide-based solvents include cyclic amide solvents such as N,N'-dimethylimidazolidineone and N-methylpyrrolidone. N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionic acid and other chain acetamide solvents.

[0278] Examples of ester-based solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; Diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate are polyol partial ether acetate solvents; Lactone solvents such as γ-butyrolactone and valproic acid; Diethyl carbonate, ethyl carbonate, propyl carbonate, and other carbonate solvents; Solvents consisting of polycarboxylic acid diesters such as propylene glycol diacetate, methoxytriethylene glycol acetate, diethyl oxalate, ethyl acetate, ethyl lactate, and diethyl phthalate.

[0279] Examples of hydrocarbon solvents include: aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Aromatic hydrocarbon solvents such as benzene, toluene, diisopropylbenzene, and n-pentylnaphthalene.

[0280] Among these, alcohol-based solvents, ester-based solvents, and ketone-based solvents are preferred; more preferably, monool-based solvents, polyol partial ether acetate-based solvents, polycarboxylic acid diester-based solvents, cyclic ketone-based solvents, and lactone-based solvents are preferred; further preferably, diacetone alcohol, propylene glycol monomethyl ether acetate, ethyl lactate, cyclohexanone, and γ-butyrolactone are also preferred. The radiosensitive linear resin composition may also contain one or more solvents.

[0281] <Other arbitrary ingredients> In addition to the components mentioned above, the radiosensitive linear resin composition may also contain any other arbitrary components. Examples of such other arbitrary components include: crosslinking agents, accelerators for partial crosslinking, surfactants, compounds containing alicyclic skeletons, sensitizers, etc. One or more of these other arbitrary components may be used.

[0282] <Preparation Method of Radiation-Inducing Linear Resin Composition> The radiosensitive linear resin composition can be prepared, for example, by mixing an onium salt, a base resin (at least one of a radiosensitive linear acid generating resin and resins) and a solvent, and any other components as needed, in a prescribed ratio. Preferably, the radiosensitive linear resin composition is filtered, for example, using a filter with a pore size of approximately 0.05 μm to 0.2 μm after mixing. The solid content concentration of the radiosensitive linear resin composition is typically 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0283] Pattern Formation Methods The pattern forming method of this embodiment includes: Step (1) (hereinafter also referred to as "resist film formation step") involves directly or indirectly coating the radiosensitive linear resin composition onto a substrate to form a resist film. Step (2) of exposing the resist film (hereinafter also referred to as the "exposure step"); and The step (3) of developing the exposed resist film (hereinafter also referred to as the "development step").

[0284] According to the pattern forming method described above, high-quality resist patterns can be formed by using the radiosensitive linear resin composition, which has excellent sensitivity or CDU performance in the exposure step and excellent suppression of development residue in the development step. The following describes each step.

[0285] [Resist film formation steps] In this step (step (1)), a resist film is formed using the radiosensitive linear resin composition. Examples of substrates for forming the resist film include silicon wafers, silicon dioxide wafers, and aluminum-coated wafers, as previously known. Alternatively, organic or inorganic antireflective films disclosed in Japanese Patent Application Publication No. 6-12452 or Japanese Patent Application Publication No. 59-93448 may be formed on the substrate. Examples of coating methods include spin coating, cast coating, and roll coating. After coating, a pre-bake (PB) may be performed as needed to allow the solvent in the coating to evaporate. The PB temperature is typically 60°C to 140°C, preferably 80°C to 120°C. The PB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0286] In the case of immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine content resin in the radiosensitive linear resin composition, a liquid-immersion protective film that is insoluble in the liquid-immersion solution can be provided on the formed resist film to avoid direct contact between the immersion solution and the resist film. As the liquid-immersion protective film, either a solvent-removable protective film that is peeled off with a solvent before the development step (e.g., see Japanese Patent Application Laid-Open No. 2006-227632) or a developer-removable protective film that is peeled off simultaneously with the development step (e.g., see WO2005-069076 and WO2006-035790) can be used. From the viewpoint of throughput, a developer-removable liquid-immersion protective film is preferred.

[0287] In addition, when using radiation with a wavelength of 50 nm or less as the next step for the exposure step, it is preferable to use a resin having the structural units (I) to (IV) and, if necessary, structural units (V) as the base resin in the composition.

[0288] [Exposure Steps] In this step (step (2)), a photomask (which may be a liquid immersion medium such as water) exposes the resist film formed in step (1), i.e., the resist film formation step, to radiation. The radiation used for exposure can be, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and gamma rays, depending on the linewidth of the target pattern; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred; more preferably, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV; and even more preferably, electron beams and EUV with wavelengths below 50 nm, which are positioned as next-generation exposure technologies.

[0289] When exposure is performed by liquid immersion, the liquid used as the immersion liquid can be, for example, water, fluorine-based inactive liquids, etc.

[0290] Preferably, post-exposure bake (PEB) is performed after the exposure, in which acid generated by a self-induced radioactive linear acid generator during exposure is used to promote the dissociation of acid-dissociating groups in the resin or the like. This PEB creates a difference in solubility of the developer between the exposed and unexposed areas. The PEB temperature is typically 50°C to 180°C, preferably 80°C to 130°C. The PEB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0291] [Developing Steps] In this step (step (3)), the resist film exposed in step (2), i.e., the exposure step, is developed. This forms a predetermined resist pattern. Generally, after development, the film is rinsed with a solution such as water or alcohol and then dried.

[0292] As a developing solution for the aforementioned development, in the case of alkaline development, examples include alkaline aqueous solutions containing 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, tetramethyl ammonium 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.

[0293] In addition, when developing with organic solvents, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents. Examples of such organic solvents include one or more solvents listed as solvents for the composition of the radiosensitive linear resin. Among these, ester solvents and ketone solvents are preferred. As ester solvents, acetate solvents are preferred, more preferably n-butyl acetate or amyl acetate. As ketone solvents, chain ketones are preferred, more preferably 2-heptanone. The content of organic solvent in the developing solution is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, particularly preferably 99% by mass or more. Other components in the developing solution besides organic solvents include, for example, water and silicone oil.

[0294] Examples of development methods include: immersing the substrate in a tank filled with developer for a certain time (immersion method); developing the substrate by using surface tension to accumulate developer on the substrate surface and allowing it to stand for a certain time (puddle method); spraying developer onto the substrate surface (spraying method); and continuously spraying developer onto a substrate rotating at a certain speed while scanning the developer spray nozzle at a certain speed (dynamic distribution method), etc. [Example]

[0295] The present invention is illustrated below with synthetic examples, embodiments, and comparative examples, but the present invention is not limited to the embodiments described below. Methods for measuring various physical properties are shown below.

[0296] [Mw and Mn] The Mw and Mn of the polymer were determined by gel permeation chromatography (GPC) using GPC columns manufactured by Tosoh Corporation (two "G2000HXL", one "G3000HXL", and one "G4000HXL") under the following conditions. Dissolution solution: Tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0297] The following shows the structures of the radiosensitive linear acid generators PAG1 to PAG13, which are strontium or ferrous salts used in the radiosensitive linear resin compositions of the embodiments.

[0298] [Chemistry 64]

[0299] [Chemistry 65]

[0300] [Synthetic Examples] Synthesis of basic polymers (P-1) to (P-9) The monomers were combined and copolymerized in tetrahydrofuran (THF) solvent, crystallized in methanol, and then repeatedly washed with hexane for separation and drying to obtain the base polymers (P-1) to (P-9) with the compositions shown below. The composition of the obtained base polymers was confirmed by 1H-NMR, and the Mw and dispersion (Mw / Mn) were confirmed by the GPC (solvent: THF, standard: polystyrene). P-1: Mw=7,700, Mw / Mn=1.7 P-2: Mw=8.000, Mw / Mn=1.7 P-3: Mw=8,200, Mw / Mn=1.7 P-4: Mw=7,600, Mw / Mn=1.7 P-5: Mw=7,500, Mw / Mn=1.7 P-6: Mw=7,900, Mw / Mn=1.7 P-7: Mw=7,600, Mw / Mn=1.7 P-8: Mw=8,000, Mw / Mn=1.8 P-9: Mw=7, 100, Mw / Mn=1.6

[0301] [Chemistry 66]

[0302] [Chemistry 67]

[0303] [Example, Comparative Example] The components shown in Table 1 were dissolved in a solvent containing 100 ppm of 3M FC-4430 as a surfactant to prepare a solution. The solution was then filtered using a 0.2 μm filter to prepare the radiosensitive linear resin composition.

[0304] The components are listed in Table 1 below. Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) GBL (γ-butyrolactone) CHN (Cyclohexanone) PGME (Propylene Glycol Monomethyl Ether) DAA (diacetone alcohol) EL (ethyl lactate)

[0305] Acid diffusion control agent (Q-1) ~ Acid diffusion control agent (Q-5) [Chemistry 68]

[0306] High-fluorine content resin F-1: Mw=8,900, Mw / Mn=2.0 [Chemistry 69]

[0307] [Evaluation of sensitivity based on EUV exposure] Using a spin coater (Tokyo Electron Inc.'s "CLEAN TRACK ACT12"), a base antireflective film forming composition (Brewer Science's "ARC66") was applied to a 12-inch silicon wafer, followed by heating at 205°C for 60 seconds to form a base antireflective film with an average thickness of 105 nm. Using the same spin coater, the various radiosensitive linear resin compositions shown in Table 1 were applied to this base antireflective film, and then heated at 130°C for 60 seconds (PB). Subsequently, the film was cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. The resist film was exposed using an EUV scanner (ASML's NXE3300 with numerical aperture (NA) 0.33, σ 0.9 / 0.6, quadrupole illumination, and a mask for a 46 nm pitch hole pattern with +20% offset on the wafer). PEB was applied for 60 seconds on a heated plate at 120°C, followed by 30 seconds of development using a 2.38% (w / w) tetramethylammonium hydroxide (TMAH) aqueous solution to form a resist pattern with 23 nm holes and a 46 nm pitch. The exposure value used to form this 23 nm hole, 46 nm pitch resist pattern was defined as the optimal exposure (Eop), and the optimal exposure value was set to the sensitivity (mJ / cm²).

[0308] [CDU's Evaluation] The resist pattern with 23 nm apertures and 46 nm spacing was formed by irradiating with the Eop value calculated above and performing the same operation as described above. The resist pattern was observed from the top using a scanning electron microscope (Hitachi High-Technologies CG-5000). The aperture size at 16 points within a 500 nm range was measured, and the average value was calculated. In addition, the average value of a total of 500 points was measured at any random point. The 3 sigma value was calculated based on the distribution of the measured values, and the calculated 3 sigma value was set as the evaluation value (nm) for CDU performance. Regarding CDU performance, the smaller the evaluation value, the smaller the aperture deviation over long periods, and the better. The results are shown in Table 1.

[0309] [Evaluation of developer residue] The same operation as described above is performed until a resist film with an average thickness of 55 nm is formed, thereby fabricating a wafer with a resist film. Next, without pattern exposure using an EUV scanner, PEB is directly applied to a heated plate at 120°C for 60 seconds. Then, development is performed using a 2.38% (w / w) TMAH aqueous solution for 30 seconds, followed by rinsing with pure water for 30 seconds and drying. Wafers for evaluating development residue are fabricated in this manner. The wafer is inspected using a COMPLUS defect inspection device (manufactured by AMAT Corporation), and the presence or absence of residue defects is confirmed using a SEM RS5500 defect review device (manufactured by Hitachi High-Technologies Co., Ltd.), and the number of residue defects is counted. Based on the counted number of residue defects, the following indicators are used for evaluation. A: Below 5 B: 6~10 C:11~20 D:21~50 E:51 and above

[0310] [Table 1] base resin (parts by weight) PAG (parts by weight) Acid diffusion Control agent (parts by weight) solvent (parts by weight) additive (parts by weight) Sensitivity [mJ / cm 2] CDU [nm] development residue Example 1 P-1 (100) PAG1 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (2.0) 14 2.4 D Example 2 P-1 (100) PAG2 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (2.0) 13 2.4 C Example 3 P-1 (100) PAG3 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (2.0) 13 2.4 B Example 4 P-1 (100) PAG4 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (2.0) 12 2.4 A Example 5 P-1 (100) PAG5 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (2.0) 12 2.4 A Example 6 P-1 (100) PAG6 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (2.0) 12 2.4 A Example 7 P-2 (100) PAG7 (5.0) Q-1 (3.0) PGMEA / PGME (2,000 / 500) F-1 (2.0) 13 2.4 B Example 8 P-3 (100) PAG8 (5.5) Q-1 (3.0) PGMEA / PGME (1,000 / 1,000) F-1 (2.0) 13 2.4 B Example 9 P-4 (100) PAG9 (6.5) Q-2 (3.0) PGMEA / GBL (2,200 / 300) F-1 (2.5) 13 2.4 B Example 10 P-5 (100) PAG1 (7.0) Q-2 (3.0) PGME / EL (2,000 / 500) F-1 (2.5) 13 2.4 B Example 11 P-6 (100) PAG9 (7.5) Q-2 (3.0) PGME / CHN (2,100 / 400) F-1 (2.5) 13 2.3 B Example 12 P-7 (100) PAG10 (6.0) Q-1 (3.5) PGME / GBL (2,100 / 400) F-1 (2.5) 13 2.3 B Example 13 P-8 (100) PAG3 (6.0) Q-1 (2.5) PGMEA / PGME / EL (1,500 / 500 / 500) F-1 (2.5) 13 2.3 B Example 14 P-1 (100) PAG11 (6.0) Q-1 (2.5) PGMEA / EL (2,000 / 500) F-1 (2.5) 13 2.3 B Example 15 P-1 (100) PAG3 (6.0) Q-3 (3.0) PGMEA / EL (2,000 / 500) F-1 (2.5) 13 2.3 B Example 16 P-1 (100) PAG12 (6.0) Q-2 (2.5) PGMEA / EL (2,000 / 500) F-1 (3.0) 13 2.3 B Example 17 P-1 (100) PAG9 (6.0) Q-4 (2.5) PGMEA / EL (2,000 / 500) F-1 (3.0) 13 2.3 B Example 18 P-1 (100) PAG12 (6.0) Q-5 (2.5) PGMEA / EL (2,000 / 500) F-1 (3.0) 13 2.1 B Example 19 P-1 (100) PAG13 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (2.0) 12 2.2 A Comparative Example 1 P-9 (100) PAG3 (6.0) Q-1 (3.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 14 2.5 B Comparative Example 2 P-1 (100) PAG9 (6.0) Q-1 (4.0) PGMEA / DAA (2,000 / 500) F-1 (3.0) 15 2.4 E

[0311] The resist pattern formed by the EUV exposure was evaluated, and the results showed that the radiosensitive linear resin composition of the embodiment had good sensitivity, CDU performance and developer residue suppression. [Industrial Applicability]

[0312] According to the radiation-sensitive linear resin composition and resist pattern formation method described above, resist patterns with good sensitivity to exposure light, excellent CDU performance, and superior resistance to developing residue can be formed. Therefore, these are preferably used in the fabrication processes of semiconductor devices that are expected to be further miniaturized in the future.

[0313] none

Claims

1. A radiosensitive linear resin composition comprising: a resin containing structural units represented by the following formula (1), wherein the content of the structural units represented by the following formula (1) is from 10 mol% to 70 mol% relative to all structural units constituting the resin; one or more onium salts comprising an organic acid anionic portion and an onium cation portion, wherein at least a portion of the organic acid anionic portion of the onium salt comprises an iodine-substituted aromatic ring structure; and a solvent, wherein at least a portion of the onium cation portion of the onium salt comprises an aromatic ring structure having a fluorine atom, wherein in the formula (1), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms, Y1 is a divalent linker, and X1 is an acid-dissociable group.

2. The radiosensitive linear resin composition as claimed in claim 1, wherein, The onium salt is selected from at least one of the following groups: a radiosensitive linear acid generator comprising the anionic portion of the organic acid radical and the cation portion of the onium; and an acid diffusion control agent comprising the anionic portion of the organic acid radical and the cation portion of the onium, and which, upon irradiation by radiation, produces an acid with a pKa higher than that produced by the radiosensitive linear acid generator, wherein at least one of the onium cation portion of the radiosensitive linear acid generator and the onium cation portion of the acid diffusion control agent comprises the aromatic ring structure having a fluorine atom.

3. The radiosensitive linear resin composition as described in claim 1 or claim 2, wherein, The organic acid anion moiety comprises a structure represented by formula (bd1) or formula (b1), wherein in formula (bd1), Rx1 to Rx4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of two or more of these; Ry1 to Ry2 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of these; is a double bond or a single bond; Rz1 to Rz4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of two or more of these; however, at least one of Rx1 to Rx4, Ry1 to Ry2, and Rz1 to Rz4 has an acid anion structure; in formula (b1), Rb1 is a monovalent hydrocarbon group with 17 to 50 carbon atoms having a steroid skeleton; Yb1 is a divalent linker group containing a heteroatom or a single bond; Vb1 is an alkylene group, a fluorinated alkylene group, or a single bond; Rfa and Rfb are independently hydrogen atoms, fluorine atoms, or fluorinated alkyl groups with 1 to 5 carbon atoms, respectively; Zb1 has an anion structure of an acid radical.

4. The radiosensitive linear resin composition as described in claim 1 or claim 2, wherein, X1 in formula (1) is represented by formula (s1) or formula (s2) below. In formula (s1), Cy is an aliphatic cyclic group formed together with a carbon atom; Ra01 to Ra03 are, respectively, hydrogen atoms, substituted or unsubstituted monovalent chain saturated hydrocarbon groups with 1 to 10 carbon atoms, or substituted or unsubstituted monovalent aliphatic cyclic saturated hydrocarbon groups with 3 to 20 carbon atoms, or represent an aliphatic cyclic structure formed by the combination of two or more of these, wherein the aliphatic cyclic structure does not form a cross-linked structure; In formula (s2), Cy has the same meaning as in formula (s1); Ra04 is a substituted or unsubstituted aromatic hydrocarbon group; In the formula, * represents a bond with an oxygen atom.

5. The radiosensitive linear resin composition as described in claim 1 or claim 2, wherein, The resin further comprises structural units having phenolic hydroxyl groups.

6. The radiosensitive linear resin composition as described in claim 1 or claim 2, wherein, The resin further comprises structural units containing at least one of the group consisting of lactone structures, cyclic carbonate structures and sulfonyl lactone structures.

7. The radiosensitive linear resin composition as described in claim 1 or claim 2, further comprising a high fluorine content resin with a higher mass content of fluorine atoms than said resin.

8. A radiosensitive linear resin composition comprising: a resin containing structural units represented by formula (1) below, wherein the content of structural units represented by formula (1) below is from 10 mol% to 70 mol% relative to all structural units constituting the resin; one or more onium salts comprising an anionic portion of an organic acid radical and a cationic portion of onium; and a solvent, wherein at least a portion of the cationic portion of the onium salt comprises an aromatic ring structure having a fluorine atom, wherein in formula (1), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms, Y1 is a divalent linker, and X1 is an acid-dissociable group, wherein, The organic acid anion portion comprises the following formula (bd1), in which Rx1 to Rx4 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group, or represent a ring structure formed by the combination of two or more of these; Ry1 to Ry2 form a ring structure formed by the combination of these; is a double bond or a single bond; and Rz1 to Rz4 form a ring structure formed by the combination of two or more of these; however, at least one of Rx1 to Rx4, Ry1 to Ry2, and Rz1 to Rz4 has an acid anion structure.

9. A method for forming a pattern, comprising: The step of directly or indirectly coating a linearly induced resin composition as described in any one of claims 1 to 8 onto a substrate to form a resist film; The steps of exposing the resist film; and developing the exposed resist film using a developing solution.

10. The pattern forming method as described in claim 9, wherein, The exposure is performed using extreme ultraviolet light or an electron beam.

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