Onium salt, photoacid generator, chemically amplified resist composition and pattern forming method

Abstract

The present invention provides an onium salt monomer represented by the following general formula (A), which enables the realization of a chemically amplified resist composition that exhibits excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby exhibiting excellent lithography performance. [Formula 1] TIFF0007813423000115.tif2895[where, SO3 - R located at the α- and / or β-position relative to the group 1 and R 2 At least one of W is a pentafluorosulfanyl group or a substituted tetrafluorosulfanyl group. 1 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. 2 is a hydrocarbyl group having 6 to 60 carbon atoms and containing at least one aromatic ring.

Description

[Technical Field]

[0001] The present invention relates to an onium salt, a photoacid generator, a chemically amplified resist composition, and a pattern forming method. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming increasingly finer. The expansion of the flash memory market and the increasing storage capacity are driving this trend. The most advanced miniaturization technology is ArF lithography, which is currently used to mass-produce 65nm node devices, and preparations are underway for mass production of next-generation 45nm node devices using ArF immersion lithography. For next-generation 32nm node devices, immersion lithography using an ultra-high NA lens that combines a liquid with a higher refractive index than water, a high-refractive-index lens, and a high-refractive-index resist film; extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm; and double exposure (double patterning lithography) of ArF lithography are candidates for which investigation is underway.

[0003] The chemically amplified resist compositions used in lithography contain compounds that decompose upon exposure to generate acid (hereinafter referred to as "photoacid generators"). Optimizing the structure of the photoacid generators can suppress acid diffusion, enabling the formation of high-resolution patterns. In general, shortening the acid diffusion length eliminates image blurring caused by acid diffusion, resulting in good mask dimension dependency (mask error enhancement factor: MEEF) and dimension uniformity (CDU).

[0004] On the other hand, since ArF immersion lithography uses a light source with a wavelength of 193 nm, it is most common to select a photoacid generator that is highly transparent at a wavelength of 193 nm. Therefore, by incorporating an alicyclic structure such as adamantane or norbornane into the photoacid generator, acid diffusion can be effectively suppressed. Furthermore, structures such as adamantanone and norbornane lactone, which incorporate heteroatoms such as oxygen atoms, can further suppress acid diffusion. Patent Document 1 proposes an acid generator containing a specific alicyclic structure.

[0005] Conventional photoacid generators enhance their acidity by having an electron-withdrawing group such as a halogen atom near the acid-generating site. In particular, because fluorine atoms have the highest electronegativity, onium salts containing perfluoroalkanesulfonic acid anions are commonly used as photoacid generators. However, the acid generated, perfluoroalkanesulfonic acid, lacks a decomposable group such as an ester structure and is hardly decomposed in nature. Therefore, it is a persistent compound that remains in the environment for a long period of time. Furthermore, because it is water-soluble, it diffuses widely through aqueous systems, causing a significant environmental impact and becoming a problem in modern society.

[0006] The health effects of perfluoroalkyl substances (PFAS) have been pointed out, and there are moves to impose restrictions on the production and sale of PFAS compounds under the European REACH Act. Many compounds containing PFAS are currently used in semiconductor lithography. For example, materials containing PFAS are used in surfactants, acid generators, etc. The photoacid generators described in Patent Documents 2 and 3 are both based on fluoroalkanesulfonic acid units, and these have been pointed out to have significant health and environmental impacts.

[0007] Patent Document 4 describes onium salts using fluorobenzenesulfonic acid as an alternative to PFAS. Photoacid generators with a fluorobenzenesulfonic acid structure do not contain fluoroalkanesulfonic acid within their structure, reducing their impact on health and the environment. While electron-withdrawing groups can increase the acid strength of sulfonic acid, photoacid generators with benzenesulfonic acid have low solubility in organic solvents, increasing the risk of defects due to precipitation from the resist casting solvent and during development.

[0008] Patent Documents 5 to 12 describe various onium salts that can be used as photoacid generators and compositions containing onium salts. However, there has been a need for the development of a new photoacid generator that can exhibit excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability when used in an acid-catalyzed chemically amplified resist composition, thereby realizing a chemically amplified resist composition that exhibits excellent lithography performance. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-117200 [Patent Document 2] Japanese Patent Application Publication No. 2018-5224 [Patent Document 3] Japanese Patent Application Publication No. 2018-197853 [Patent Document 4] Japanese Patent Application Publication No. 2018-159744 [Patent Document 5] International Publication No. 2024 / 185543 [Patent Document 6] International Publication No. 2018 / 168252 [Patent Document 7] International Publication No. 2024 / 143131 [Patent Document 8] International Publication No. 2024 / 241766 [Patent Document 9] Japanese Patent Application Publication No. 2018-049177 [Patent Document 10] Japanese Patent Application Laid-Open No. 2015-4967 [Patent Document 11] International Publication No. 2024 / 225059 [Patent Document 12] Japanese Patent Application Laid-Open No. 2025-79775 Summary of the Invention [Problem to be solved by the invention]

[0010] There is a need for the development of acid-catalyzed chemically amplified resist compositions that have high solubility in the resist's casting solvent, even higher sensitivity, and excellent acid diffusion suppression capabilities, and that are capable of improving lithography performance such as LWR, CDU, exposure latitude (EL), depth of focus (DOF), and mask dimension effect factor (MEEF), as well as having excellent etching resistance after pattern formation.

[0011] The present invention has been made in view of the above circumstances, and has an object to provide an onium salt that, when used in an acid-catalyzed chemically amplified resist composition, exhibits excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby realizing a chemically amplified resist composition that exhibits excellent lithography performance; a photoacid generator comprising the onium salt; a chemically amplified resist composition containing the photoacid generator; and a pattern formation method using the chemically amplified resist composition. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides an onium salt characterized by being represented by the following general formula (A): [ka] [In the formula, m1 is an integer of 1 to 4. m2 is 0 or 1. R 1 and R 2are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxy group, an amino group, a mercapto group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylsulfonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a pentafluorosulfanyl group, and a substituted tetrafluorosulfanyl group in which one fluorine atom in the pentafluorosulfanyl group is replaced with a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group, an aryl group, or a heterocycle; - R located at the α- and / or β-position relative to the group 1 and R 2 At least one of the groups is a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the above substituent. L A and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, a carbonyl group, or a hydrocarbylene group having 1 to 10 carbon atoms, and the hydrocarbylene group may contain an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, or a carbonyl group. stomach. W 1 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. W 2represents a hydrocarbyl group having 6 to 60 carbon atoms and containing at least one aromatic ring, which may contain a heteroatom, and the aromatic ring may be substituted with a halogen atom, a nitro group, a hydroxy group, a cyano group, a pentafluorosulfanyl group, a hydrocarbyl group having 1 to 20 carbon atoms and which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms and which may contain a heteroatom, or a hydrocarbylthio group having 1 to 20 carbon atoms and which may contain a heteroatom. Z + is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)]

[0013] In the onium salt of the present invention, R 1 and / or R 2 Of which SO3 - The pentafluorosulfanyl group or substituted tetrafluorosulfanyl group located at the α-position and / or β-position relative to the group has high electron-withdrawing properties, which can increase the acid strength of the sulfonate anion moiety by utilizing not only the inductive effect but also the resonance effect, thereby improving sensitivity and solubility in organic solvents. Furthermore, the presence of multiple sulfur atoms substituted on fluorine atoms also contributes to high solubility in organic solvents. Furthermore, since the pentafluorosulfanyl group or substituted tetrafluorosulfanyl group is a sterically bulky substituent, a photoacid generator derived from an onium salt monomer represented by the above general formula (A) having such a substituent can suppress acid diffusion when used in a chemically amplified resist composition, thereby improving LWR, CDU, DOF, and MEEF. In particular, the onium salt of the present invention is a W 2is a hydrocarbyl group having 6 to 60 carbon atoms and containing at least one aromatic ring, and therefore has a bulky and rigid structure, which can reduce the mobility of the sulfonate anion moiety, thereby suppressing acid diffusion and ultimately achieving better CDU, LWR, and MEEF.

[0014] As a result, when the onium salt of the present invention is used in an acid-catalyzed chemically amplified resist composition, it exhibits excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby realizing a chemically amplified resist composition that exhibits excellent lithography performance. In particular, when used in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), or EUV, the onium salt of the present invention, while being non-PFAS, can exhibit higher solubility in solvents than existing photoacid generators based on fluorobenzenesulfonic acid or benzenesulfonic acid, and can realize a chemically amplified resist composition that has high sensitivity, high contrast, and excellent lithography performance such as LWR, CDU, EL, DOF, and MEEF, and is resistant to pattern collapse even in fine pattern formation.

[0015] SO3 - R located α to the group 1 and / or R 2 is preferably a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the above substituent.

[0016] In this preferred embodiment, the pentafluorosulfanyl (SF5) group or the substituted tetrafluorosulfanyl group exhibits particularly high solubility in organic solvents and particularly high electron-withdrawing properties, and therefore, further improved sensitivity can be achieved.

[0017] It is particularly preferred that the molecule contains two or more iodine atoms.

[0018] Onium salts containing two or more iodine atoms in the molecule can exhibit high absorption of high-energy rays, especially EUV, and therefore can achieve better sensitivity. Furthermore, when the onium salt has multiple aromatic rings, an onium salt containing two or more iodine atoms in one aromatic ring can exhibit higher molecular rigidity than an onium salt containing one iodine atom in each aromatic ring, and as a result, can exhibit better acid diffusion suppression ability. Such onium salts can achieve better LWR. Considering solubility in solvents, an onium salt having two or three iodine atoms in one molecule, which are grouped into a W group, is preferred. 2 It is particularly preferred that the aromatic ring is substituted with the group represented by the formula (I).

[0019] SO3 - R located α to the group 1 and / or R 2 is particularly preferably a pentafluorosulfanyl group.

[0020] Sulfonate anion moiety (SO3 - It is particularly preferred that the α-position relative to the group) is substituted with a pentafluorosulfanyl group, in which case the acid strength and sensitivity are highest.

[0021] The present invention also provides a photoacid generator comprising the onium salt of the present invention.

[0022] For the reasons explained above, when such a photoacid generator of the present invention is used in a chemically amplified resist composition that uses an acid as a catalyst, it exhibits excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby making it possible to realize a chemically amplified resist composition that exhibits excellent lithography performance.

[0023] The present invention also provides a chemically amplified resist composition, which is characterized by containing the photoacid generator of the present invention.

[0024] Such a chemically amplified resist composition of the present invention contains the photoacid generator of the present invention, and therefore can exhibit excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby exhibiting excellent lithography performance.

[0025] The chemically amplified resist composition may further contain a base polymer.

[0026] The chemically amplified resist composition of the present invention typically comprises a base polymer.

[0027] In this case, the base polymer may contain a repeating unit represented by the following formula (b1) or (b2): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms which contains at least one bond selected from an ester bond, an ether bond, and a lactone ring, and the phenylene group, naphthylene group, and linking group may contain at least one bond selected from a hydroxy group, a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, and a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms. Y 2 is a single bond or an ester bond. Y 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13 is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbylcarbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R 14represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one bond selected from the group consisting of a hydroxy group, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms, an ether bond, and an ester bond. a is an integer from 0 to 4.

[0028] Such a chemically amplified resist composition can be a positive resist composition, or the chemically amplified resist composition of the present invention can be a negative resist composition in organic solvent development even in the absence of a crosslinking agent or the like.

[0029] The chemically amplified resist composition may further contain, for example, at least one selected from the group consisting of an organic solvent, a quencher, a surfactant, and a dissolution inhibitor.

[0030] Thus, the chemically amplified resist composition of the present invention can contain the above components depending on the application.

[0031] Further, the present invention provides a pattern forming method, comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition of the present invention; exposing the resist film to high-energy radiation; developing the exposed resist film using a developer; The present invention provides a pattern forming method comprising the steps of:

[0032] The pattern forming method of the present invention uses the chemically amplified resist composition of the present invention, so that patterns can be formed with excellent LWR, CDU, EL, DOF, MEEF, etc., that is, excellent lithography performance.

[0033] For example, the high energy beam may be KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

[0034] In the pattern formation method of the present invention, the specific form of the high-energy beam is not particularly limited, but for example, the high-energy beams described above can be used. [Effects of the Invention]

[0035] As described above, in the onium salt of the present invention, R 1 and / or R 2 Of these, sulfonate anions (SO3 - The acid strength of the sulfonate anion moiety is increased by the pentafluorosulfanyl group or substituted tetrafluorosulfanyl group located at the α-position and / or β-position relative to the sulfonate anion (SO3 - The pentafluorosulfanyl group or the substituted tetrafluorosulfanyl group has an aromatic ring in a group separate from the tetrafluorosulfanyl group (group), and the steric bulkiness of the pentafluorosulfanyl group or the substituted tetrafluorosulfanyl group is comparable to that of a t-butyl group, thereby suppressing acid diffusion. As a result, lithography performance such as LWR, CDU, EL, DOF, and MEEF can be improved.

[0036] For the reasons described above, a chemically amplified resist composition containing such an onium salt of the present invention as a photoacid generator can exhibit excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby exhibiting excellent lithography performance. DETAILED DESCRIPTION OF THE INVENTION

[0037] As described above, there has been a need for the development of an acid-catalyzed chemically amplified resist composition that exhibits high solubility in a resist casting solvent, even higher sensitivity, and excellent acid diffusion suppression ability, and that is capable of improving lithography performance such as LWR, CDU, exposure latitude (EL), depth of focus (DOF), and MEEF, as well as exhibiting excellent etching resistance after pattern formation.

[0038] As a result of extensive research to achieve the above object, the present inventors have found that the sulfonate anion moiety (SO3 - The α- and / or β-positions relative to the sulfonic acid anion (SO3 - The present inventors have found that by using an onium salt containing an aromatic ring in a group separate from the (aromatic group) moiety as a photoacid generator, the acid strength of the sulfonate anion moiety can be increased, and a chemically amplified resist composition can be obtained that has high solubility in organic solvents, high sensitivity, high resolution, and improved lithography performance such as LWR, CDU, EL, DOF, and MEEF, thereby completing the present invention.

[0039] That is, the present invention relates to an onium salt characterized by being represented by the following general formula (A): [ka] [In the formula, m1 is an integer of 1 to 4. m2 is 0 or 1. R 1 and R 2 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxy group, an amino group, a mercapto group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylsulfonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a pentafluorosulfanyl group, and a substituted tetrafluorosulfanyl group in which one fluorine atom in the pentafluorosulfanyl group is replaced with a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group, an aryl group, or a heterocycle;- R located at the α- and / or β-position relative to the group 1 and R 2 At least one of the groups is a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the above substituent. L A and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, a carbonyl group, or a hydrocarbylene group having 1 to 10 carbon atoms, and the hydrocarbylene group may contain an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, or a carbonyl group. W 1 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. W 2 represents a hydrocarbyl group having 6 to 60 carbon atoms and containing at least one aromatic ring, which may contain a heteroatom, and the aromatic ring may be substituted with a halogen atom, a nitro group, a hydroxy group, a cyano group, a pentafluorosulfanyl group, a hydrocarbyl group having 1 to 20 carbon atoms and which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms and which may contain a heteroatom, or a hydrocarbylthio group having 1 to 20 carbon atoms and which may contain a heteroatom. Z + is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)]

[0040] The present invention will be described in detail below, but the present invention is not limited thereto.

[0041] [Onium salts] The onium salt of the present invention is represented by the following general formula (A). [ka]

[0042] <Anion part> In general formula (A), m1 is an integer of 1 to 4. m1 is preferably 1 or 2, and more preferably 1. When m1 is an integer of 1 to 4, the mobility of the sulfonate anion moiety decreases, making it possible to suppress acid diffusion.

[0043] In general formula (A), R 1 and R 2 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxy group, an amino group, a mercapto group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylsulfonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a pentafluorosulfanyl group, and a substituted tetrafluorosulfanyl group in which one fluorine atom in the pentafluorosulfanyl group is replaced with a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group, an aryl group, or a heterocycle; - R located at the α- and / or β-position relative to the group 1 and R 2 At least one of the groups is a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the above substituent.

[0044] The pentafluorosulfanyl group and substituted tetrafluorosulfanyl group have high electron-withdrawing properties, which not only enhance the acidity of the sulfonate anion moiety by utilizing the inductive effect but also the resonance effect, thereby improving sensitivity. Furthermore, the presence of multiple sulfur atoms substituted by fluorine atoms contributes to high solubility in organic solvents. Furthermore, the pentafluorosulfanyl group and substituted tetrafluorosulfanyl group are sterically bulky substituents, and by being positioned at the α- and / or β-position relative to the sulfonate anion moiety, they can suppress acid diffusion due to the sulfonate anion moiety. These results can improve LWR, CDU, DOF, and MEEF.

[0045] The substituted tetrafluorosulfanyl group is preferably a tetrafluorosulfanyl group substituted with a halogen atom other than a fluorine atom or an aryl group. The aryl group that the substituted tetrafluorosulfanyl group may have may have a substituent such as a halogen atom, and the substituent is preferably a fluorine atom or an iodine atom. R is present at the α-position and / or β-position relative to the sulfonate anion moiety. 1 and R 2 When at least one of the groups is a tetrafluorosulfanyl group substituted with a fluorine-substituted aryl group or an iodine-substituted aryl group, the steric hindrance around the sulfonate anion moiety is even greater, which can further suppress acid diffusion and thereby improve CDU, LWR, MEEF, etc.

[0046] SO3 - R located at the α- and / or β-position relative to the group 1 and R 2 It is particularly preferred that at least one of the groups is a pentafluorosulfanyl group. In this case, the sensitivity is further improved because the compound can exhibit particularly high solubility in organic solvents and electron-withdrawing properties. In particular, the sulfonate anion moiety (SO3 - Preferably, the α-position to the SO3 group is substituted with a pentafluorosulfanyl group. - R located α to the group1 and / or R 2 is preferably a pentafluorosulfanyl group, which provides the highest acid strength and sensitivity.

[0047] The onium salt of the particularly preferred embodiment of the present invention can be specifically represented by, for example, the following general formula (A-1). [ka] [In the formula, m3 is an integer of 0 to 3. R 1 , R 2 , L B , W 1 , W 2 and Z + is the same as above. R 3 is selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxy group, an amino group, a mercapto group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylsulfonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a pentafluorosulfanyl group, and a substituted tetrafluorosulfanyl group in which one fluorine atom in the pentafluorosulfanyl group is substituted with a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group, an aryl group, or a heterocycle. L A2 is an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond.

[0048] In the above general formula (A-1), R 3is more preferably a fluorine atom. The onium salt of such an embodiment is non-PFAS, and the anion moiety can exhibit higher acid strength, resulting in higher sensitivity. In this case, hydrophobicity can be particularly improved, so that in order to ensure solubility in polar solvents, for example, W 1 and / or W 2 is particularly preferably a group containing an oxanorbornane lactone ring in which an oxygen atom is contained at the bridging position of the norbornane lactone ring.

[0049] The hydrocarbyl group and the hydrocarbyl moiety of the hydrocarbyloxy group and hydrocarbylthio group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclopropyl ... Examples of the alkyl group include saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a hexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; unsaturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group; aryl groups having 2 to 20 carbon atoms, such as a phenyl group and a naphthyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, an oxanorbornane lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0050] Alternatively, the sulfonate anion moiety (SO3 -It is also preferred that the α-position relative to the sulfonate anion moiety is substituted with a hexafluorosulfanyl group. An onium salt having such a structure has large steric hindrance around the sulfonate anion moiety, and can further suppress acid diffusion, thereby achieving better CDU, better LWR, and better MEEF.

[0051] In general formula (A), L A and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, a carbonyl group, or a hydrocarbylene group having 1 to 10 carbon atoms, and the hydrocarbylene group may contain an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, or a carbonyl group. A The bond is preferably an ether bond or an ester bond, and more preferably an ether bond. In this case, the degree of freedom of the sulfonate anion moiety is reduced, and acid diffusion can be further suppressed. B As the bond, an ester bond or a sulfonate ester bond is preferred, in which case the acid strength of the sulfonate anion moiety is further increased, further improving sensitivity.

[0052] In general formula (A), W 1 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom.

[0053] W 1 Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a hetero atom, represented by the formula (I), include, but are not limited to, those shown below. In the formula (I), * represents L A and L B It is a combination of.

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] Of these, W 1 -0~W 1 -22, W 1 -29~W 1 -34, and W 1 -47~W 1 -63 is preferred, W 1 is more preferably an aromatic ring substituted with an iodine atom. In this case, the presence of the aromatic ring substituted with an iodine atom, which has high EUV absorption, allows for higher sensitivity. The number of iodine atoms substituting the aromatic ring is preferably 1 to 2, and more preferably 2. The more iodine atoms substituted, the higher the EUV absorption and the higher the sensitivity. However, by limiting the number of iodine atoms substituted to 1 to 2, higher solubility in resist solvents can be achieved compared to monomers containing units such as triiodobenzene or tetraiodobenzene.

[0059] As mentioned above, the onium salt is R 3 In the case where W is a fluorine atom, in order to ensure solvent solubility, 1 is preferably a group containing an oxanorbornane lactone ring.

[0060] Also, W 1 Onium salts having a polycyclic structure such as adamantane can exhibit higher rigidity than onium salts having a single ring structure such as cyclohexane, thereby achieving good CDU, LWR, and MEEF.

[0061] W 1 Preferably, W contains a lactone ring structure or a sultone structure. 1 However, by having a polar group such as a lactone ring structure or a sultone structure, acid diffusion in the chemically amplified resist composition can be reliably suppressed.

[0062] In general formula (A), W 2 represents a hydrocarbyl group having 6 to 60 carbon atoms and containing at least one aromatic ring, which may contain a heteroatom, and the aromatic ring may be substituted with a halogen atom, a nitro group, a hydroxy group, a cyano group, a pentafluorosulfanyl group, a hydrocarbyl group having 1 to 20 carbon atoms and which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms and which may contain a heteroatom, or a hydrocarbylthio group having 1 to 20 carbon atoms and which may contain a heteroatom.

[0063] W 2 Specific examples of the formula include, but are not limited to, the following: In the formula, * represents L A or L B It is a combination of.

[0064] [ka]

[0065] [ka]

[0066] W 2 is more preferably an aromatic ring substituted with an iodine atom, and W 2It is most preferable that the aromatic ring is substituted with an iodine atom. In this case, the presence of the aromatic ring substituted with an iodine atom, which has high EUV absorption, allows for higher sensitivity. The number of iodine atoms substituting the aromatic ring is preferably 1 to 2, and more preferably 2. The more iodine atoms substituted, the higher the EUV absorption and the higher the sensitivity. However, by limiting the number of iodine atoms substituted to 1 to 2, higher solubility in resist solvents can be achieved compared to monomers containing units such as triiodobenzene or tetraiodobenzene.

[0067] Incidentally, it is particularly preferable that the onium salt contains two or more iodine atoms in the molecule. Onium salts containing two or more iodine atoms in the molecule can exhibit higher absorption of high-energy rays, especially EUV, and therefore can achieve better sensitivity. Furthermore, when the compound has multiple aromatic rings, onium salts containing two or more iodine atoms in one aromatic ring can exhibit higher molecular rigidity than onium salts containing one iodine atom in each aromatic ring, and as a result, can exhibit better acid diffusion suppression ability. Such onium salts can achieve better LWR. Considering solubility in solvents, onium salts containing two or three iodine atoms in one molecule, which are grouped into W, are preferable. 2 It is particularly preferred that the aromatic ring is substituted with the group represented by the formula (I).

[0068] Furthermore, the onium salt of the present invention preferably has multiple aromatic rings, which can reduce molecular diffusion and achieve a further improved LWR.

[0069] Furthermore, the onium salt of the present invention preferably has an alicyclic group such as a lactone ring, which allows it to exhibit appropriate solubility in appropriate polar solvents, thereby improving the removability during, for example, TMAH development, and achieving a superior CDU.

[0070] Furthermore, the onium salt of the present invention preferably has multiple substituents with lone electron pairs, such as methoxy groups or nitro groups, which can quench the acid and achieve better LWR and CDU.

[0071] Specific examples of the anion of the onium salt represented by general formula (A) include, but are not limited to, the following: 。 In addition, the bonding positions of the various substituents on the ring may be interchanged.

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] <Cation part> In general formula (A), Z + is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2).

[0082] [ka]

[0083] In general formulas (Z-1) and (Z-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0084] R ct1 ~R ct5 Specific examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0085] R ct1 ~R ct5The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; saturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 30 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 30 carbon atoms, such as phenyl, naphthyl, and thienyl; aralkyl groups having 7 to 30 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these, with aryl groups being preferred. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0086] Also, R ct1 and R ct2 However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, specific examples of the ring structure include those represented by the following formulas.

[0087] [ka] (In the formula, the dashed line indicates R ct3 )

[0088] Specific examples of the sulfonium cation represented by general formula (Z-1) include, but are not limited to, the following:

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099]

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[0100]

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[0101]

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[0103]

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[0104]

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[0105]

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[0106]

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[0107]

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[0108]

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[0109]

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[0110]

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[0119]

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[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] Specific examples of the iodonium cation represented by general formula (Z-2) include, but are not limited to, the following: [ka]

[0126] [ka]

[0127] Specific examples of the onium salt of the present invention include any combination of the above-mentioned anions and the above-mentioned cations.

[0128] The onium salt of the present invention can be synthesized, for example, by a method similar to that for synthesizing a sulfonium salt having a polymerizable anion described in Japanese Patent No. 5201363, but the method for producing the onium salt of the present invention is not limited thereto.

[0129] [Photoacid generator] The photoacid generator of the present invention comprises the onium salt of the present invention.

[0130] For the reasons explained above, when such a photoacid generator of the present invention is used in a chemically amplified resist composition that uses an acid as a catalyst, it exhibits excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby making it possible to realize a chemically amplified resist composition that exhibits excellent lithography performance.

[0131] [Chemically amplified resist composition] The chemically amplified resist composition of the present invention is characterized by containing the photoacid generator of the present invention.

[0132] Such a chemically amplified resist composition of the present invention contains the photoacid generator of the present invention, and therefore can exhibit excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby exhibiting excellent lithography performance.

[0133] The chemically amplified resist composition of the present invention may further contain components other than the photoacid generator of the present invention. Optional components of the chemically amplified resist composition of the present invention will now be described.

[0134] <Base polymer> The chemically amplified resist composition of the present invention can typically include a base polymer.

[0135] For example, the chemically amplified resist composition of the present invention preferably further contains a base polymer that includes a repeating unit having an acid labile group.

[0136] Such a chemically amplified resist composition can be a positive resist composition.

[0137] In this case, the base polymer contains, for example, a repeating unit represented by the following formula (b1) or (b2), but is not limited thereto. [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms which contains at least one bond selected from an ester bond, an ether bond, and a lactone ring, and the phenylene group, naphthylene group, and linking group may contain at least one bond selected from a hydroxy group, a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, and a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms. Y 2 is a single bond or an ester bond. Y 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13 is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbylcarbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R 14 represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one bond selected from the group consisting of a hydroxy group, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms, an ether bond, and an ester bond. a is an integer from 0 to 4.

[0138] The repeating unit having an acid labile group is not particularly limited, but may be, for example, one represented by the above general formula (b1) or (b2).

[0139] Specific examples of the monomer that provides the repeating unit b1 include, but are not limited to, the following: A and R 11 is the same as above.

[0140] [ka]

[0141] [ka]

[0142] Specific examples of the monomer that provides the repeating unit b2 include, but are not limited to, the following: A and R 12 is the same as above.

[0143] [ka]

[0144] R 11 or R 12 The acid labile group represented by the formula (AL-1) may be selected from a variety of groups, and examples thereof include those represented by the following formulae (AL-1) to (AL-3).

[0145] [ka] (In the formula, the dashed lines represent bonds.)

[0146] In formula (AL-1), b is 0, 1, 2, 3, 4, 5 or 6. L1 is a tertiary hydrocarbyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trihydrocarbylsilyl group in which each hydrocarbyl group is a saturated hydrocarbyl group having 1 to 6 carbon atoms, a carbonyl group, or a saturated hydrocarbyl group having 4 to 20 carbon atoms containing an ether bond or an ester bond, or a group represented by formula (AL-3). The tertiary hydrocarbyl group means a group obtained by eliminating a hydrogen atom from a tertiary carbon atom of a hydrocarbon.

[0147] R L1The tertiary hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be branched or cyclic. Specific examples thereof include tert-butyl, tert-pentyl, 1,1-diethylpropyl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl, and 2-methyl-2-adamantyl. Specific examples of the trihydrocarbylsilyl group include trimethylsilyl, triethylsilyl, and dimethyl-tert-butylsilyl. The saturated hydrocarbyl group containing a carbonyl group, an ether bond, or an ester bond may be linear, branched, or cyclic, but is preferably cyclic. Specific examples thereof include a 3-oxocyclohexyl group, a 4-methyl-2-oxooxan-4-yl group, a 5-methyl-2-oxoxolan-5-yl group, a 2-tetrahydropyranyl group, and a 2-tetrahydrofuranyl group.

[0148] Specific examples of the acid labile group represented by formula (AL-1) include a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a tert-pentyloxycarbonyl group, a tert-pentyloxycarbonylmethyl group, a 1,1-diethylpropyloxycarbonyl group, a 1,1-diethylpropyloxycarbonylmethyl group, a 1-ethylcyclopentyloxycarbonyl group, a 1-ethylcyclopentyloxycarbonylmethyl group, a 1-ethyl-2-cyclopentenyloxycarbonyl group, a 1-ethyl-2-cyclopentenyloxycarbonylmethyl group, a 1-ethoxyethoxycarbonylmethyl group, a 2-tetrahydropyranyloxycarbonylmethyl group, and a 2-tetrahydrofuranyloxycarbonylmethyl group.

[0149] Further, examples of the acid labile group represented by formula (AL-1) include groups represented by the following formulae (AL-1)-1 to (AL-1)-10.

[0150] [ka] (In the formula, the dashed lines represent bonds.)

[0151] In formulae (AL-1)-1 to (AL-1)-10, b is the same as defined above. L8 are each independently a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. L9 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. L10 is a saturated hydrocarbyl group having 2 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic.

[0152] In formula (AL-2), R L2 and R L3 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclopentyl group, a cyclohexyl group, a 2-ethylhexyl group, and an n-octyl group.

[0153] In formula (AL-2), R L4 is a hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10, which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples of the hydrocarbyl group include saturated hydrocarbyl groups having 1 to 18 carbon atoms, and some of the hydrogen atoms may be substituted with a hydroxy group, an alkoxy group, an oxo group, an amino group, an alkylamino group, or the like. Specific examples of such substituted saturated hydrocarbyl groups include those shown below.

[0154] [ka] (In the formula, the dashed lines represent bonds.)

[0155] R L2 and R L3 , R L2 and R L4 , or R L3 and R L4 may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom and oxygen atom, and in this case, R L2 and R L3 , R L2 and R L4 , or R L3 and R L4 are each independently an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10. The ring obtained by combining these groups preferably has 3 to 10 carbon atoms, more preferably 4 to 10 carbon atoms.

[0156] Specific examples of linear or branched acid labile groups represented by formula (AL-2) include, but are not limited to, those represented by the following formulae (AL-2)-1 to (AL-2)-69, in which the dashed lines represent bonds.

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] [ka]

[0161] Specific examples of cyclic acid labile groups represented by formula (AL-2) include a tetrahydrofuran-2-yl group, a 2-methyltetrahydrofuran-2-yl group, a tetrahydropyran-2-yl group, and a 2-methyltetrahydropyran-2-yl group.

[0162] Further, examples of the acid labile group include groups represented by the following formula (AL-2a) or (AL-2b): The polymer may be inter- or intramolecularly crosslinked by the acid labile group.

[0163] [ka] (In the formula, the dashed lines represent bonds.)

[0164] In formula (AL-2a) or (AL-2b), R L11 and R L12 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 8 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. L11 and R L12 may be bonded to each other to form a ring together with the carbon atoms to which they are attached, in which case R L11 and R L12 are each independently an alkanediyl group having 1 to 8 carbon atoms. L13 are each independently a saturated hydrocarbylene group having 1 to 10 carbon atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic. c and d are each independently an integer of 0 to 10, preferably 0, 1, 2, 3, 4, or 5, and e is an integer of 1 to 7, preferably 1, 2, or 3.

[0165] In formula (AL-2a) or (AL-2b), L Ais an (e+1)-valent aliphatic saturated hydrocarbon group having 1 to 50 carbon atoms, an (e+1)-valent alicyclic saturated hydrocarbon group having 3 to 50 carbon atoms, an (e+1)-valent aromatic hydrocarbon group having 6 to 50 carbon atoms, or an (e+1)-valent heterocyclic group having 3 to 50 carbon atoms. In addition, some of the -CH2- groups may be substituted with a group containing a hetero atom, and some of the hydrogen atoms in these groups may be substituted with a hydroxy group, a carboxy group, an acyl group, or a fluorine atom. A As L, saturated hydrocarbon groups such as saturated hydrocarbylene groups having 1 to 20 carbon atoms, trivalent saturated hydrocarbon groups, and tetravalent saturated hydrocarbon groups, and arylene groups having 6 to 30 carbon atoms are preferred. The saturated hydrocarbon groups may be linear, branched, or cyclic. B is -C(=O)-O-, -NH-C(=O)-O-, or -NH-C(=O)-NH-.

[0166] Specific examples of the crosslinked acetal group represented by formula (AL-2a) or (AL-2b) include groups represented by the following formulae (AL-2)-70 to (AL-2)-77.

[0167] [ka] (In the formula, the dashed lines represent bonds.)

[0168] In formula (AL-3), R L5 R is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and fluorine atoms. L6 and R L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, and aryl groups having 6 to 10 carbon atoms. In addition, RL5 and R L6 Paired with R L5 and R L7 Pair with or R L6 and R L7 and the groups may be bonded to each other to form an alicyclic ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded.

[0169] Specific examples of the group represented by formula (AL-3) include a tert-butyl group, a 1,1-diethylpropyl group, a 1-ethylnorbornyl group, a 1-methylcyclopentyl group, a 1-ethylcyclopentyl group, a 1-isopropylcyclopentyl group, a 1-methylcyclohexyl group, a 2-(2-methyl)adamantyl group, a 2-(2-ethyl)adamantyl group, and a tert-pentyl group.

[0170] Specific examples of the group represented by formula (AL-3) also include groups represented by the following formulae (AL-3)-1 to (AL-3)-22.

[0171] [ka] (In the formula, the dashed lines represent bonds.)

[0172] In formulas (AL-3)-1 to (AL-3)-22, R L14 are each independently a hydrogen atom, an aliphatic hydrocarbyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 20 carbon atoms. L15 and R L17 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. L16 is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. The aryl group is preferably a phenyl group. R L18 is a fluorine atom, an iodine atom, a nitro group, or a trifluoromethyl group. L19are each independently a hydrogen atom, a fluorine atom, an iodine atom, a nitro group, a saturated hydrocarbyl group having 1 to 8 carbon atoms, or a hydrocarbyloxy group having 1 to 8 carbon atoms.

[0173] Further examples of the acid labile group include groups represented by the following formula (AL-3)-23 or (AL-3)-24: The acid labile group may cause intramolecular or intermolecular crosslinking of the polymer.

[0174] [ka] (In the formula, the dashed lines represent bonds.)

[0175] In formulas (AL-3)-23 and (AL-3)-24, R L14 is the same as above. R L20 is a (g+1)-valent saturated or unsaturated hydrocarbylene group having 1 to 20 carbon atoms or a (g+1)-valent arylene group having 6 to 20 carbon atoms, and may contain heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. The saturated or unsaturated hydrocarbylene group may be linear, branched, or cyclic. g is 1, 2, or 3.

[0176] In addition to these acid labile groups, aromatic group-containing acid labile groups described in Japanese Patent Nos. 5565293, 5434983, 5407941, 5655756 and 5655755 can also be used.

[0177] The base polymer may further contain a repeating unit c containing a phenolic hydroxy group as an adhesive group. Specific examples of the monomer that provides the repeating unit c include, but are not limited to, the following. In the following formula, R A is the same as above.

[0178] [ka]

[0179] The base polymer may further contain a repeating unit d containing, as another adhesive group, a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonate ester bond, a carbonyl group, a sulfonyl group, a cyano group, or a carboxy group. Specific examples of monomers that provide the repeating unit d include, but are not limited to, those shown below. In the following formula, R A is the same as above.

[0180] [ka]

[0181] [ka]

[0182] [ka]

[0183] [ka]

[0184] [ka]

[0185] [ka]

[0186] [ka]

[0187] [ka]

[0188] The base polymer may further contain a repeating unit e derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene or derivatives thereof. Specific examples of the monomer that gives the repeating unit e include, but are not limited to, those shown below.

[0189]

Chemical formula

[0190] The base polymer may further contain a repeating unit f derived from styrene, vinyl naphthalene, vinyl anthracene, vinyl pyrene, methylene indane, vinyl pyridine or vinyl carbazole.

[0191] The base polymer for the positive resist composition essentially contains a repeating unit containing an acid-labile group, for example, repeating unit b1 or b2. In this case, the content ratios of the repeating units b1, b2, c, d, e and f are preferably 0≦b1<1.0, 0≦b2<1.0, 0<b1 + b2<1.0, 0≦c≦0.9, 0≦d≦0.9, 0≦e≦0.8 and 0≦f≦0.8, more preferably 0≦b1≦0.9, 0≦b2≦0.9, 0.1≦b1 + b2≦0.9, 0≦c≦0.8, 0≦d≦0.8, 0≦e≦0.7, 0≦f≦0.7, and still more preferably 0≦b1≦0.8, 0≦b2≦0.8, 0.1≦b1 + b2≦0.8, 0≦c≦0.75, 0≦d≦0.75, 0≦e≦0.6 and 0≦f≦0.6. Also, b1 + b2 + c + d + e + f = 1.0.

[0192] On the one hand, for the base polymer for a negative resist composition, an acid-labile group is not necessarily required. Examples of such a base polymer include those containing repeating unit c and optionally further containing repeating units d, e, and / or f. The content ratios of these repeating units are preferably 0 < c ≤ 1.0, 0 ≤ d ≤ 0.9, 0 ≤ e ≤ 0.8, and 0 ≤ f ≤ 0.8, more preferably 0.2 ≤ c ≤ 1.0, 0 ≤ d ≤ 0.8, 0 ≤ e ≤ 0.7, and 0 ≤ f ≤ 0.7, and still more preferably 0.3 ≤ c ≤ 1.0, 0 ≤ d ≤ 0.75, 0 ≤ e ≤ 0.6, and 0 ≤ f ≤ 0.6. Also, c + d + e + f = 1.0.

[0193] Examples of the method for synthesizing the base polymer include, for example, a method in which a monomer that provides the aforementioned repeating unit is heated in an organic solvent with a radical polymerization initiator added thereto to perform polymerization.

[0194] Specific examples of the organic solvent used during polymerization include toluene, benzene, tetrahydrofuran (THF), methyl ethyl ketone (MEK), diethyl ether, and dioxane. Specific examples of the radical polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The temperature during polymerization is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

[0195] When copolymerizing a monomer containing a hydroxy group, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid such as an ethoxyethoxy group before polymerization and then deprotected with a weak acid and water after polymerization, or it may be substituted with an acetyl group, a formyl group, or a pivaloyl group and then subjected to alkaline hydrolysis after polymerization.

[0196] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group may be deprotected by the alkaline hydrolysis to give hydroxystyrene or hydroxyvinylnaphthalene.

[0197] The base that can be used in alkaline hydrolysis includes aqueous ammonia, triethylamine, etc. The reaction temperature is preferably −20 to 100° C., more preferably 0 to 60° C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0198] The weight-average molecular weight (Mw) of the polymer is preferably 1,000 to 500,000, more preferably 3,000 to 100,000. Within this range, there is no risk of a decrease in etching resistance or a decrease in resolution due to an inability to ensure contrast before and after exposure. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0199] If the polymer has a broad molecular weight distribution (Mw / Mn), low-molecular-weight and high-molecular-weight polymers will be present, which may result in the appearance of foreign matter on the pattern or deterioration of the pattern shape after exposure. As the pattern rules become finer, the effects of Mw and Mw / Mn tend to become greater, so in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that the Mw / Mn of the polymer has a narrow distribution of 1.0 to 2.0, particularly 1.0 to 1.5.

[0200] Furthermore, when the base polymer has a narrow molecular weight distribution (Mw / Mn), the presence of low-molecular-weight and high-molecular-weight polymers is suppressed, and the appearance of foreign matter on the pattern and deterioration of the pattern shape after exposure can be suppressed. As the pattern rule becomes finer, the effects of Mw and Mw / Mn tend to become greater, so in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that the base polymer have a narrow distribution of Mw / Mn of 1.0 to 2.0, and particularly 1.0 to 1.5.

[0201] The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw / Mn.

[0202] The chemically amplified resist composition of the present invention preferably contains 0.1 to 40 parts by weight, and more preferably 0.1 to 20 parts by weight, of the photoacid generator of the present invention per 100 parts by weight of the base polymer.

[0203] <Organic solvents> The chemically amplified resist composition may further contain, for example, an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the photoacid generator of the present invention and each optional component. Specific examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] and

[0145] of JP-A No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ... ethers such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono-tert-butyl ether acetate, and propylene glycol mono-tert-butyl ether acetate; and lactones such as γ-butyrolactone.

[0204] In the chemically amplified resist composition of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvent may be used alone or in combination of two or more.

[0205] <Fluorine atom-containing polymer> Furthermore, the chemically amplified resist composition of the present invention may further comprise (D) a fluorine atom-containing polymer containing at least one selected from the group consisting of a repeating unit represented by the following general formula (D1), a repeating unit represented by the following general formula (D2), a repeating unit represented by the following general formula (D3), and a repeating unit represented by the following general formula (D4): [ka] (In the formula, R B is a hydrogen atom or a methyl group. R 21 and R 22 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. R 23 is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. R 24 , R 25 and R 26 R are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, an acyl group having 2 to 15 carbon atoms, or an acid labile group. 24 , R 25 and R 26 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, a portion of these -CH2- groups may be substituted with an ether bond or a carbonyl group. R 27 is a (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. k is an integer of 1 to 3. X 21 are each independently a single bond, an ester bond, an ether bond, an amide bond or a phenylene bond. p is an integer of 1 or 2. X 22 are each independently a single bond or a hydrocarbylene group having 1 to 20 carbon atoms when p is 1, or a trivalent hydrocarbon group having 1 to 20 carbon atoms when p is 2, and the hydrocarbylene group and the trivalent hydrocarbon group may contain at least one atom selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. X 23 are each independently a single bond, an ester bond, an ether bond, an amide bond, a sulfonate ester bond, a urethane bond, a thiourethane bond, or a urea bond. Ar is a group derived from benzene or naphthalene. R 28are each independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 6 carbon atoms, a hydroxy group, a carboxy group, a halogen atom, a cyano group, or a nitro group. m is an integer from 1 to 5.

[0206] Examples of the repeating unit represented by formula (D1) include, but are not limited to, those shown below. B is the same as above.

[0207] [ka]

[0208] Examples of the repeating unit represented by formula (D2) include, but are not limited to, those shown below. B is the same as above. [ka]

[0209] Examples of the repeating unit represented by formula (D3) include, but are not limited to, those shown below. In the following formula, R B is the same as above. [ka]

[0210] Examples of the repeating unit represented by formula (D4) include, but are not limited to, those shown below. B is the same as above.

[0211] [ka]

[0212] The fluorine atom-containing polymer may further contain other repeating units in addition to the repeating units represented by any one of formulas (D1) to (D4). Specific examples of the other repeating units include repeating units obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. Fluorine atom-containing polymer The content of the repeating units represented by formulae (D1) to (D4) in all repeating units is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %.

[0213] The Mw of the fluorine atom-containing polymer of component (D) is preferably from 1,000 to 100,000, and more preferably from 3,000 to 15,000. The Mw / Mn is preferably from 1.0 to 2.0, and more preferably from 1.0 to 1.6.

[0214] A method for synthesizing the fluorine-containing polymer of component (D) includes a method in which a monomer providing at least one repeating unit selected from the group consisting of a repeating unit represented by formula (D1), a repeating unit represented by formula (D2), a repeating unit represented by formula (D3), and a repeating unit represented by formula (D4), and optionally a monomer providing other repeating units, is heated in an organic solvent with the addition of a radical initiator to polymerize. Examples of organic solvents used in the polymerization reaction include toluene, benzene, THF, diethyl ether, dioxane, methyl ethyl ketone, propylene glycol monomethyl ether, and PGMEA. Examples of the polymerization initiator include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization reaction temperature is preferably 50 to 100°C. The amount of these initiators added is preferably 0.01 to 25 mol% based on the total amount of monomers to be polymerized. The reaction time is preferably 4 to 24 hours. The acid labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization. To adjust the molecular weight, the polymerization may be carried out using a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol. In this case, the amount of the chain transfer agent added is preferably an amount that provides a molar ratio of 0.01 to 10 relative to the total monomers to be polymerized.

[0215] When the chemically amplified resist composition of the present invention contains the fluorine atom-containing polymer (D), the content thereof is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the base polymer (B). When the content of the fluorine atom-containing polymer (D) is within the above range, the contact angle between the resist film surface and water is sufficiently improved, thereby suppressing defects due to residual immersion water and elution of the acid generator and quencher. Furthermore, it becomes possible to adjust the solubility of the resist film surface, thereby achieving a good CDU. The fluorine atom-containing polymer (D) may be used alone or in combination of two or more types.

[0216] <Quencher> The chemically amplified resist composition of the present invention may contain a quencher, if necessary. In the present invention, the quencher refers to a compound that can trap the acid generated from the photoacid generator, thereby preventing the acid from diffusing into unexposed areas.

[0217] Specific examples of the quencher include amine compounds, sulfonates, and carboxylates. The amine compounds are preferably primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP 2008-111103 A, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond. Also preferred are compounds in which a primary or secondary amine is protected as a carbamate group, such as the compounds described in JP 3790649 A. Such protected amine compounds are effective when the resist composition contains a base-unstable component.

[0218] Specific examples of the sulfonate include a compound represented by the following formula (1): Furthermore, specific examples of the carboxylate include a compound represented by the following formula (2):

[0219] [ka]

[0220] In formula (1), R 101 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, but SO3 - Excluding those in which the hydrogen atom bonded to the carbon atom at the α-position of the group is substituted with a fluorine atom or a fluoroalkyl group.

[0221] R 101The hydrocarbyl group having 1 to 40 carbon atoms and represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 ]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as decanyl group, adamantyl group, and adamantylmethyl group; alkenyl groups having 2 to 40 carbon atoms such as vinyl group, 1-propenyl group, 2-propenyl group, butenyl group, and hexenyl group; unsaturated aliphatic cyclic hydrocarbyl groups having 3 to 40 carbon atoms such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (for example, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, and 4-n-butylphenyl group), diphenyl ether group, ... Alkylphenyl and triphenyl groups Examples of such alkyl groups include aryl groups having 6 to 40 carbon atoms, such as alkylphenyl groups (for example, 2,4-dimethylphenyl groups and 2,4,6-triisopropylphenyl groups), alkylnaphthyl groups (for example, methylnaphthyl groups and ethylnaphthyl groups), and dialkylnaphthyl groups (for example, dimethylnaphthyl groups and diethylnaphthyl groups); and aralkyl groups having 7 to 40 carbon atoms, such as benzyl groups, 1-phenylethyl groups, and 2-phenylethyl groups.

[0222] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. Examples of hydrocarbyl groups containing heteroatoms include heteroaryl groups such as thienyl groups; alkoxyphenyl groups such as 4-hydroxyphenyl groups, 4-methoxyphenyl groups, 3-methoxyphenyl groups, 2-methoxyphenyl groups, 4-ethoxyphenyl groups, 4-tert-butoxyphenyl groups, and 3-tert-butoxyphenyl groups; alkoxynaphthyl groups such as methoxynaphthyl groups, ethoxynaphthyl groups, n-propoxynaphthyl groups, and n-butoxynaphthyl groups; dialkoxynaphthyl groups such as dimethoxynaphthyl groups and diethoxynaphthyl groups; and aryloxoalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl groups, 2-(1-naphthyl)-2-oxoethyl groups, and 2-(2-naphthyl)-2-oxoethyl groups.

[0223] R 102 R is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. 102 Examples of the hydrocarbyl group represented by R 101 Examples of the hydrocarbyl group include the same groups as those exemplified above. Other specific examples include fluorine-containing alkyl groups such as a trifluoromethyl group, a trifluoroethyl group, a 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, and a 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group; and fluorine-containing aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0224] Specific examples of the anion of the sulfonate salt represented by formula (1) include, but are not limited to, those shown below.

[0225] [ka]

[0226] [ka]

[0227] Specific examples of the anion of the carboxylate represented by formula (2) include, but are not limited to, those shown below: In the following formula, Me is a methyl group.

[0228] [ka]

[0229] [ka]

[0230] [ka]

[0231] [ka]

[0232] [ka]

[0233] In equations (1) and (2), Mq +is an onium cation. Examples of the onium cation include sulfonium cation, iodonium cation, and ammonium cation. The sulfonium cation is preferably represented by formula (Z-1), and specific examples thereof include the same as those exemplified as specific examples of the sulfonium cation represented by formula (Z-1). The iodonium cation is preferably represented by formula (Z-2), and specific examples thereof include the same as those exemplified as specific examples of the iodonium cation represented by formula (Z-2).

[0234] Another example of the quencher is the polymer-type quencher described in JP 2008-239918 A. This quencher enhances the rectangularity of the resist pattern by orienting on the resist surface. The polymer-type quencher also has the effect of preventing pattern thinning and rounding of the pattern top when a protective film for immersion lithography is applied.

[0235] Furthermore, as the quencher, an onium salt having a sulfonium cation and a phenoxide anion moiety in the same molecule, as described in Japanese Patent No. 6848776, an onium salt having a sulfonium cation and a carboxylate anion moiety in the same molecule, as described in Japanese Patent No. 6583136 and JP-A-2020-200311, or an onium salt having an iodonium cation and a carboxylate anion moiety in the same molecule, as described in Japanese Patent No. 6274755, can also be used.

[0236] When the chemically amplified resist composition of the present invention contains a quencher, the content thereof is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, per 80 parts by mass of the base polymer. The incorporation of a quencher not only facilitates adjustment of the sensitivity of the resist film, but also suppresses acid diffusion within the resist film, improving resolution, suppressing sensitivity changes after exposure, and reducing substrate and environmental dependency, thereby improving exposure latitude, pattern profile, and the like. The addition of the quencher can also improve substrate adhesion. Quenchers may be used alone or in combination of two or more.

[0237] <Surfactant> The chemically amplified resist composition of the present invention may further contain a surfactant.

[0238] Specific examples of the surfactant include those described in paragraphs

[0165] and

[0166] of JP-A No. 2008-111103. Addition of a surfactant can further improve or control the coatability of the resist composition. When the resist composition of the present invention contains the surfactant, the content thereof is preferably 0.0001 to 10 parts by mass per 100 parts by mass of the base polymer. The surfactant may be used alone, or two or more types may be used in combination.

[0239] <Other ingredients> The chemically amplified resist composition of the present invention may contain, in addition to the above-mentioned components, an acid generator (or other acid generators), a dissolution inhibitor, a crosslinking agent, a water repellency enhancer, or acetylene alcohols.

[0240] Examples of the acid generator (other acid generator) include compounds (photoacid generators) that generate acid in response to actinic rays or radiation. The photoacid generator component may be any compound that generates an acid upon exposure to high-energy rays, but acid generators that generate sulfonic acid, imide acid, or methide acid are preferred. Specific examples of suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of the acid generator include those described in paragraphs

[0122] to

[0142] of JP 2008-111103 A, JP 2018-5224 A, and JP 2018-25789 A. When the resist composition of the present invention contains the acid generator, the content thereof is preferably 0 to 200 parts by mass, and more preferably 0.1 to 100 parts by mass, per 100 parts by mass of the base polymer. Since the onium salt of the present invention functions as a photoacid generator, it is not essential to separately add the other photoacid generators described above.

[0241] When the resist composition of the present invention is a positive resist composition, the incorporation of a dissolution inhibitor can further increase the difference in dissolution rate between exposed and unexposed areas, thereby further improving resolution. Specific examples of the dissolution inhibitor include compounds having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800, containing two or more phenolic hydroxy groups in the molecule, in which the hydrogen atoms of the phenolic hydroxy groups have been substituted with acid labile groups at a rate of 0 to 100 mol % overall, and compounds containing carboxy groups in the molecule, in which the hydrogen atoms of the carboxy groups have been substituted with acid labile groups at an average rate of 50 to 100 mol % overall. Specific examples include compounds in which the hydrogen atoms of the hydroxyl groups or carboxyl groups of bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid have been substituted with acid labile groups, as described, for example, in paragraphs

[0155] to

[0178] of JP 2008-122932 A.

[0242] When the chemically amplified resist composition of the present invention is a positive type and contains the dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the base polymer. The dissolution inhibitor may be used alone or in combination of two or more types.

[0243] On the other hand, when the chemically amplified resist composition of the present invention is a negative-working composition, a crosslinking agent can be added to reduce the dissolution rate of the exposed area, thereby obtaining a negative pattern. Note that the chemically amplified resist composition of the present invention can become a negative-working resist composition in organic solvent development even without the presence of a crosslinking agent or the like.

[0244] Specific examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds such as alkenyloxy groups, all of which are substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group. These may be used as additives or may be introduced as pendant groups into polymer side chains. Compounds containing hydroxy groups may also be used as crosslinking agents.

[0245] Specific examples of the epoxy compound include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0246] Specific examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated or a mixture thereof, and the like.

[0247] Specific examples of the guanamine compound include tetramethylolguanamine, tetramethoxymethylguanamine, a compound in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated, or a mixture thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, and a compound in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated, or a mixture thereof, etc.

[0248] Specific examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound in which one to four methylol groups of tetramethylol glycoluril are methoxymethylated or a mixture thereof, and a compound in which one to four methylol groups of tetramethylol glycoluril are acyloxymethylated or a mixture thereof, etc. Specific examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound in which one to four methylol groups of tetramethylol urea are methoxymethylated or a mixture thereof, and tetramethoxyethyl urea, etc.

[0249] Specific examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0250] Specific examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0251] Specific examples of the compound containing an alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

[0252] When the chemically amplified resist composition of the present invention is a negative-working composition and contains the crosslinking agent, the content thereof is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The crosslinking agent may be used alone or in combination of two or more types.

[0253] The water repellency improver improves the water repellency of the resist film surface and can be used in immersion lithography without a topcoat. Preferred examples of the water repellency improver include polymers containing fluorinated alkyl groups and polymers containing a specific 1,1,1,3,3,3-hexafluoro-2-propanol residue structure, with those exemplified in JP-A Nos. 2007-297590 and 2008-111103 being more preferred. The water repellency improver must be soluble in an alkaline developer or an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, polymers containing repeating units containing an amino group or an amine salt are highly effective in preventing the evaporation of acid during PEB and preventing poor opening of the hole pattern after development. When the chemically amplified resist composition of the present invention contains the water repellency improver, the content thereof is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more. It may also be used.

[0254] Specific examples of the acetylene alcohols include those described in paragraphs

[0179] to

[0182] of JP 2008-122932 A. When the chemically amplified resist composition of the present invention contains the acetylene alcohols, the content thereof is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The acetylene alcohols may be used alone or in combination of two or more.

[0255] [Pattern formation method] When the chemically amplified resist composition of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a specific example of a pattern formation method includes a step of forming a resist film on a substrate using the above-mentioned chemically amplified resist composition of the present invention, a step of exposing the resist film to high-energy rays, and a step of developing the exposed resist film using a developer. This example of the pattern formation method is the pattern formation method of the present invention.

[0256] The pattern forming method of the present invention uses the chemically amplified resist composition of the present invention, so that patterns can be formed with excellent LWR, CDU, EL, DOF, MEEF, etc., that is, excellent lithography performance.

[0257] The pattern forming method of the present invention will be explained in more detail below, but the pattern forming method of the present invention is not limited to the examples shown below.

[0258] First, the chemically amplified resist composition of the present invention is applied to a substrate for integrated circuit production (e.g., Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, and organic antireflective coatings) or a substrate for mask circuit production (e.g., Cr, CrO, CrON, MoSi2, and SiO2) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or doctor coating, preferably to a coating thickness of 0.01 to 2 μm. The resulting coating is then prebaked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

[0259] Next, the resist film is exposed to high-energy radiation. Specific examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, EB, EUV radiation with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. For example, the high-energy radiation may be ArF excimer laser light with a wavelength of 193 nm, KrF excimer laser light with a wavelength of 248 nm, electron beams, or extreme ultraviolet radiation with a wavelength of 3 to 15 nm. When ultraviolet radiation, far ultraviolet radiation, EUV radiation, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, or the like is used as the high-energy radiation, the exposure dose is preferably 1 to 200 mJ / cm, either directly or using a mask for forming a desired pattern. 2 approximately, more preferably 10 to 100 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 300 μC / cm 2 approximately, more preferably 0.5 to 200 μC / cm 2 The resist composition of the present invention is suitable for fine patterning using high-energy radiation such as KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, and synchrotron radiation, and is particularly suitable for fine patterning using EB or EUV.

[0260] In addition to the usual exposure method, the immersion method can be used, in which a liquid with a refractive index of 1.0 or higher is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0261] The water-insoluble protective film is used to prevent elution from the resist film and increase the water sliding property of the film surface. It can be broadly divided into two types. One is an organic solvent-removable type that requires stripping before alkaline aqueous development using an organic solvent that does not dissolve the resist film. The other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with removing the soluble portion of the resist film. The latter is particularly based on a polymer containing 1,1,1,3,3,3-hexafluoro-2-propanol residues that is insoluble in water but soluble in alkaline developer, and is preferably dissolved in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof. Materials can also be prepared by dissolving the water-insoluble, alkaline developer-soluble surfactant described above in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof.

[0262] After exposure, PEB may be performed on a hot plate or in an oven, preferably at 30 to 150° C. for 10 seconds to 30 minutes, more preferably at 50 to 120° C. for 30 seconds to 20 minutes, or may not be performed.

[0263] After exposure or PEB, the exposed resist film is developed using a developer, preferably an aqueous alkaline solution of 0.1 to 10% by weight, more preferably 2 to 5% by weight, of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or the like, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as dipping, puddling, or spraying, to form the desired pattern on the resist film. In the case of a positive chemically amplified resist composition, the irradiated portion dissolves in the developer, while the unexposed portion remains insoluble, forming the desired positive pattern on the substrate. In the case of a negative chemically amplified resist composition, the opposite is true: the irradiated portion becomes insoluble in the developer, while the unexposed portion dissolves.

[0264] A negative pattern can also be obtained by organic solvent development using a positive chemically amplified resist composition containing a base polymer containing an acid labile group.Specific examples of the developer used in this case include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, and ethyl crotonate. , methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. These organic solvents may be used alone or in combination of two or more.

[0265] After the development is completed, rinsing is performed. As a rinsing liquid, a solvent that is miscible with the developer but does not dissolve the resist film is preferred. As such a solvent, an alcohol having 3 to 10 carbon atoms, an ether compound having 8 to 12 carbon atoms, an alkane, alkene, alkyne having 6 to 12 carbon atoms, or an aromatic solvent is preferably used.

[0266] Specific examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. , 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1-octanol, and the like.

[0267] Specific examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0268] Specific examples of the alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Specific examples of the alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Specific examples of the alkynes having 6 to 12 carbon atoms include hexyne, heptine, and octyne.

[0269] Specific examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0270] Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not performing rinsing can reduce the amount of solvent used.

[0271] The developed hole or trench pattern can also be shrunk using, for example, thermal flow, RELACS, or DSA. A shrink agent is applied to the hole pattern, and the diffusion of an acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, resulting in adhesion of the shrink agent to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds. Excess shrink agent is removed, and the hole pattern is shrunk. [Example]

[0272] The present invention will be specifically explained below by showing synthesis examples, comparative synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The apparatuses used are as follows. MALDI TOF-MS: JEOL S3000

[0273] [Synthesis Example 1] Synthesis of onium salt [Synthesis Example 1-1] Synthesis of onium salt PAG-1 PAG-1 was synthesized according to the following reaction scheme.

[0274] [ka]

[0275] (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, a reaction vessel was charged with starting material SM-1 (29.0 g), oxanyl chloride (15.1 g), DMF (N,N-dimethylformamide) (0.2 g), and methylene chloride (100 g). The temperature inside the reaction vessel was raised to 35°C and aged for 3 hours. After aging, the mixture was cooled to room temperature, and the solvent was distilled off to obtain a solid. The resulting solid was dissolved in methylene chloride (60 g), and starting material SM-2 (49.6 g) and pyridine (3.1 g) were added and cooled in an ice bath. After addition, the mixture was heated to room temperature and aged for 12 hours. After aging, water was added to quench the reaction. Subsequently, the mixture was subjected to a conventional aqueous treatment, and the solvent was distilled off. The residue was then washed with diisopropyl ether, yielding 63.2 g of intermediate In-1 as crystals (yield 85%).

[0276] (2) Synthesis of PAG-1 Under a nitrogen atmosphere, intermediate In-1 (63.2 g), raw material SM-3 (53.6 g), methylene chloride (100 g), and water (50 g) were mixed and stirred for 15 minutes. The organic layer was then separated, washed with water, and then concentrated under reduced pressure. Diisopropyl ether (50 g) was added to the concentrated solution to cause crystallization, yielding 77.8 g of the target onium salt PAG-1 as white crystals (yield 90%). The analytical results of the obtained onium salt PAG-1 are as follows: MALDI TOF-MS: POSITIVE M+ 425 (C 18 H 12 F2IS + equivalent) NEGATIVE M- 593 (C8H4F5I2O5S - equivalent)

[0277] [Synthesis Examples 1-2 to 1-10] Synthesis of onium salts PAG-2 to PAG-10 Onium salts PAG-2 to PAG-10 represented by the following formulae were synthesized using the corresponding raw materials and known organic synthesis reactions.

[0278] [ka]

[0279] [Synthesis Example 2] Synthesis of base polymers (polymers P-1 to P-4) Each monomer was combined and copolymerized in THF solvent, then added to methanol. The precipitated solid was washed with hexane, isolated, and dried to obtain the base polymers (polymers P-1 to P-4) with the following compositions. The resulting base polymers were 1 The molecular weight was confirmed by H-NMR, and Mw and Mw / Mn were confirmed by GPC (solvent: THF, standard: polystyrene).

[0280] [ka]

[0281] [Example 1] Preparation and evaluation of chemically amplified resist composition [Examples 1-1 to 1-13, Comparative Examples 1-1 to 1-6] (1) Preparation of chemically amplified resist composition Predetermined components selected from the onium salts of the present invention (PAG-1 to PAG-10), comparative photoacid generators (cPAG-1 to cPAG-6), polymers (P-1 to P-4), and quencher (Q-1) were dissolved in a solvent containing 0.01 mass % of surfactant A (manufactured by Omnova) in the compositions shown in Table 1 below to prepare solutions. The solutions were then filtered through a 0.2 μm Teflon (registered trademark) filter to prepare chemically amplified resist compositions R-1 to R-13 and comparative chemically amplified resist compositions CR-1 to CR-6.

[0282] In Table 1, the components are as follows: Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) EL (Ethyl lactate) DAA (diacetone alcohol) PGME (Propylene Glycol Monomethyl Ether)

[0283] Comparative photoacid generators: cPAG-1 to cPAG-6 [ka]

[0284] Quencher: Q-1 [ka]

[0285] Surfactant A: 3-methyl-3-(2,2,2-trifluoroethoxymethyl)oxetane-tetrahydrofuran-2,2-dimethyl-1,3-propanediol copolymer (Omnova) [ka] a:(b+b'):(c+c')=1:4-7:0.01-1 (molar ratio) Mw=1500

[0286] (2) EUV Lithography Evaluation 1 Each chemically amplified resist composition shown in Table 1 was spin-coated onto a Si substrate with a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (43 wt % silicon) manufactured by Shin-Etsu Chemical Co., Ltd., and pre-baked for 60 seconds at 105°C using a hot plate to produce a 50 nm thick resist film. The resist film was exposed to light using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, 40 nm pitch on the wafer, +20% bias hole pattern mask), subjected to PEB for 60 seconds on a hot plate at the temperature shown in Table 1, and developed for 30 seconds with a 2.38 wt % TMAH aqueous solution to form a 20 nm hole pattern.

[0287] Using a Hitachi High-Technologies Corporation CD-SEM (CG6300), the exposure dose when holes were formed with a dimension of 20 nm was measured and used as the sensitivity. The smaller this value, the better the sensitivity. The dimensions of 50 holes were also measured, and the standard deviation (σ) calculated from the results was tripled (3σ) to give the CDU. The smaller this value, the better the CDU. The results are shown in Table 1.

[0288] [Table 1]

[0289] (3) MEEF evaluation The pitch was kept fixed, and the mask dimensions were changed to observe the line width of each pattern irradiated with Eop. The slope of the mask dimension and the line width of the pattern was taken as MEEF. A MEEF of 3.6 or less was considered good. All of the chemically amplified resist compositions R-1 to R-13 were able to achieve a good MEEF of 3.6 or less.

[0290] From the results shown in Table 1 and the MEEF evaluation, it was found that the resist compositions R-1 to R-13 of the examples of the present invention, which contain the photoacid generator of the example made of the onium salt of the present invention, have high sensitivity and can achieve good CDU and good MEEF.

[0291] [Example 2] EUV lithography evaluation 2 [Examples 2-1 to 2-13, Comparative Examples 2-1 to 2-6] Each of the chemically amplified resist compositions prepared above was spin-coated onto a Si substrate on which a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (43% silicon by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed, and the substrate was pre-baked at 100°C for 60 seconds using a hot plate to produce a 50 nm thick resist film. The resist film was exposed to an LS pattern with an on-wafer dimension of 18 nm and a pitch of 36 nm using an ASML EUV scanner NXE3300 (NA 0.33, σ 0.9 / 0.6, dipole illumination) while varying the exposure dose and focus (exposure dose pitch: 1 mJ / cm). 2 The exposure was performed while maintaining a constant exposure time (focus pitch: 0.020 μm). After exposure, PEB was performed for 60 seconds at the temperature shown in Table 2. Puddle development was then performed for 30 seconds using a 2.38% by mass TMAH aqueous solution, followed by rinsing with a surfactant-containing rinse solution and spin drying to obtain a positive pattern. The obtained LS pattern was observed using a critical dimension SEM (CG6300) manufactured by Hitachi High-Tech Corporation, and the sensitivity and LWR were evaluated according to the following methods. The results are shown in Table 2.

[0292] [Sensitivity evaluation] The optimum exposure dose Eop (mJ / cm) to obtain an LS pattern with a line width of 18 nm and a pitch of 36 nm 2 The smaller this value, the higher the sensitivity.

[0293] [LWR rating] The LS pattern obtained by irradiation with Eop was measured at 10 points along the line length, and the LWR was calculated as three times the standard deviation (σ) (3σ). The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0294] [Table 1]

[0295] The results shown in Table 2 indicate that the resist compositions R-1 to R-13 of the present invention, which contain the photoacid generators of the present invention made of the onium salts of the present invention, have high sensitivity and can achieve good LWR.

[0296] [Example 3] Turbidity evaluation The solubility of each photoacid generator in a 1% PGMEA solution was evaluated by measuring turbidity. Resist compositions R-1 to R-13 of the present invention, which contained a photoacid generator of the present invention consisting of an onium salt of the present invention, had a turbidity value of less than 0.5 NTU, demonstrating excellent solubility in the solvent.

[0297] Furthermore, it is presumed that the good CDU, good MEEF, and good LWR demonstrated in Examples 1 and 2 are the result of the excellent acid diffusion suppression ability of the onium salts PAG-1 to PAG-10.

[0298] The results of Examples 1 and 2 above demonstrate that the chemically amplified resist compositions R-1 to R-13 of the present invention are more useful for ArF immersion lithography than the comparative chemically amplified resist compositions CR-1 to CR-6, which use conventional photoacid generators.

[0299] This specification includes the following inventions. [1] An onium salt, characterized in that it is an onium salt represented by the following general formula (A): [ka] [In the formula, m1 is an integer of 1 to 4. m2 is 0 or 1. R 1 and R 2 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxy group, an amino group, a mercapto group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylsulfonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a pentafluorosulfanyl group, and a substituted tetrafluorosulfanyl group in which one fluorine atom in the pentafluorosulfanyl group is replaced with a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group, an aryl group, or a heterocycle; - R located at the α- and / or β-position relative to the group 1 and R 2 At least one of the groups is a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the above substituent. L A and L Bare each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, a carbonyl group, or a hydrocarbylene group having 1 to 10 carbon atoms, and the hydrocarbylene group may contain an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, or a carbonyl group. stomach. W 1 is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. W 2 represents a hydrocarbyl group having 6 to 60 carbon atoms and containing at least one aromatic ring, which may contain a heteroatom, and the aromatic ring may be substituted with a halogen atom, a nitro group, a hydroxy group, a cyano group, a pentafluorosulfanyl group, a hydrocarbyl group having 1 to 20 carbon atoms and which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms and which may contain a heteroatom, or a hydrocarbylthio group having 1 to 20 carbon atoms and which may contain a heteroatom. Z + is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)] [2] SO3 - R located α to the group 1 and / or R 2 is a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the substituent. [3] The onium salt according to [1] or [2], which contains two or more iodine atoms in the molecule. [4]SO3 - R located α to the group 1 and / or R 2 The onium salt according to any one of [1] to [3], wherein is a pentafluorosulfanyl group. [5] A photoacid generator comprising the onium salt according to any one of [1] to [4]. [6] A chemically amplified resist composition, comprising the photoacid generator according to [5]. [7] The chemically amplified resist composition according to [6], further comprising a base polymer. [8] The base polymer is characterized in that it contains a repeating unit represented by the following formula (b1) or (b2): [7] The chemically amplified resist composition according to claim 1. [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms which contains at least one bond selected from an ester bond, an ether bond, and a lactone ring, and the phenylene group, naphthylene group, and linking group may contain at least one bond selected from a hydroxy group, a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, and a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms. Y 2 is a single bond or an ester bond. Y 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbylcarbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R 14 represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one bond selected from the group consisting of a hydroxy group, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms, an ether bond, and an ester bond. a is an integer from 0 to 4. [9] The chemically amplified resist composition according to any one of [6] to [8], further comprising at least one selected from the group consisting of an organic solvent, a quencher, a surfactant, and a dissolution inhibitor.

[10] A pattern formation method, comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to any one of [6] to [9]; exposing the resist film to high-energy radiation; and developing the exposed resist film using a developer. A pattern forming method comprising the steps of:

[11] The pattern forming method according to

[10] , wherein the high-energy beam is KrF excimer laser beam, ArF excimer laser beam, electron beam, or extreme ultraviolet ray having a wavelength of 3 to 15 nm.

[0300] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An onium salt, characterized in that it is an onium salt represented by the following general formula (A): 【Chemistry 1】 [In the formula, m1 is an integer of 1 to 4. m2 is 0 or 1. R １ and R ２ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxy group, an amino group, a mercapto group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylthio group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxycarbonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylsulfonyl group having 1 to 20 carbon atoms which may contain a heteroatom, a pentafluorosulfanyl group, and a substituted tetrafluorosulfanyl group in which one fluorine atom in the pentafluorosulfanyl group is replaced with a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group, an aryl group, or a heterocycle; ３ － R located at the α-position and / or β-position relative to the group １ and R ２ At least one of the groups is a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the above substituent. L Ａ and L Ｂ are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, a carbonyl group, or a hydrocarbylene group having 1 to 10 carbon atoms, and the hydrocarbylene group may contain an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, a sulfonyl group, or a carbonyl group. W １ is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. W ２ is a hydrocarbyl group containing 6 to 60 carbon atoms and containing at least one aromatic ring, which may contain a heteroatom, and the aromatic ring may be substituted with a halogen atom, a nitro group, a hydroxy group, a cyano group, a pentafluorosulfanyl group, a hydrocarbyl group containing 1 to 20 carbon atoms and which may contain a heteroatom, a hydrocarbyloxy group containing 1 to 20 carbon atoms and which may contain a heteroatom, or a hydrocarbylthio group containing 1 to 20 carbon atoms and which may contain a heteroatom. Z ＋ is a sulfonium cation represented by the following general formula (Z-1) or an iodonium cation represented by the following general formula (Z-2). 【Chemistry 2】 (In the formula, R ｃｔ１ ~R ｃｔ５ are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ｃｔ１ and R ｃｔ２ may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

2. SO ３ － R located α to the group １ and / or R ２ 2. The onium salt according to claim 1, wherein is a pentafluorosulfanyl group or a tetrafluorosulfanyl group containing the substituent.

3. 2. The onium salt according to claim 1, which contains two or more iodine atoms in the molecule.

4. SO ３ － R located α to the group １ and / or R ２ 2. The onium salt according to claim 1, wherein is a pentafluorosulfanyl group.

5. A photoacid generator comprising the onium salt according to any one of claims 1 to 4.

6. A chemically amplified resist composition, comprising the photoacid generator according to claim 5.

7. 7. The chemically amplified resist composition according to claim 6, further comprising a base polymer.

8. 8. The chemically amplified resist composition according to claim 7, wherein the base polymer contains a repeating unit represented by the following formula (b1) or (b2): 【Transformation 3】 (In the formula, R Ａ are each independently a hydrogen atom or a methyl group. Y １ is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms which contains at least one bond selected from an ester bond, an ether bond, and a lactone ring, and the phenylene group, naphthylene group, and linking group may contain at least one bond selected from a hydroxy group, a halogen atom, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, and a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms. Y ２ is a single bond or an ester bond. Y ３ is a single bond, an ether bond or an ester bond. R １１ and R １２ are each independently an acid labile group. R １３ is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbylcarbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R １４ represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one bond selected from the group consisting of a hydroxy group, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms, an ether bond, and an ester bond. a is an integer from 0 to 4.

9. 7. The chemically amplified resist composition according to claim 6, further comprising at least one selected from the group consisting of an organic solvent, a quencher, a surfactant, and a dissolution inhibitor.

10. A pattern formation method, comprising: forming a resist film on a substrate using the chemically amplified resist composition according to claim 6; exposing the resist film to high-energy radiation; developing the exposed resist film using a developer; A pattern forming method comprising the steps of:

11. 11. The pattern forming method according to claim 10, wherein the high-energy beam is KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

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