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

Abstract

The present invention relates to an onium salt represented by the general formula (A). Thereby, in photolithography using high-energy rays, an onium salt used in a chemically amplified resist composition having high sensitivity and excellent lithography performance such as CDU and LWR is provided. 【Chemical 1】 TIFF0007852169000130.tif2895[m1 is 1 to 4. m2 is 0 or 1. R 1 is either a hydrogen atom, a hydrocarbyl group, or an electron-withdrawing group such as a cyano group. L A and L B are a single bond, a carbonyl group, an ether bond, an ester bond, etc. W 1 and W 2 At least one of them has an aromatic ring. (W 2 -[L A -W 1 m2 -L B -) The moiety represented by has at least two iodine atoms directly bonded to the aromatic ring. Z + is an onium cation. ]​

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] With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. In particular, the expansion of the flash memory market and the increase in storage capacity are driving this miniaturization. As for the most advanced miniaturization technology, mass production of 65nm node devices using ArF lithography is underway, and preparations for mass production of next-generation 45nm node devices using ArF immersion lithography are underway. For next-generation 32nm node devices, immersion lithography using ultra-high NA lenses combining 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 among the candidates and are currently being investigated.

[0003] The chemically amplified resist composition used in the aforementioned lithography employs a compound that decomposes upon exposure to generate acid (hereinafter referred to as "photoacid generator"). By optimizing the structure within the photoacid generator, acid diffusion can be suppressed, enabling the formation of high-resolution patterns. Generally, shortening the acid diffusion length eliminates image blurring due to acid diffusion, resulting in good mask dimension dependence (mask error increase factor: MEEF) and dimensional 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 alicyclic structures such as adamantane and norbornane into the acid generator, acid diffusion can be effectively suppressed. Furthermore, structures such as adamantanone and norbornane lactone, which incorporate heteroatoms such as oxygen atoms into these structures, can further suppress acid diffusion. Patent Document 1 proposes an acid generator containing a specific alicyclic structure.

[0005] Conventional photoacid generators increase acidity by having electron-withdrawing groups, such as halogen atoms, near the acid generation site. In particular, because fluorine atoms have the highest electronegativity, onium salts containing perfluoroalkanesulfonic acid anions are commonly used as photoacid generators. However, the generated acid, perfluoroalkanesulfonic acid, lacks degradable groups such as ester structures and hardly decomposes in nature, making it a persistent compound that remains in the environment for long periods. Furthermore, because it is water-soluble, it diffuses widely through water systems, resulting in a significant environmental burden and becoming a problem in modern society.

[0006] The health effects of perfluoroalkyl compounds (PFAS) have been pointed out, and there are movements to restrict the manufacture and sale of PFAS compounds under the European REACH initiative. Many compounds containing PFAS are currently used in semiconductor lithography. For example, materials containing PFAS are used in surfactants and acid generators. The photoacid generators described in Patent Documents 2 and 3 are all based on fluoroalkanesulfonic acid units, and these have been criticized for their significant impact on health and the environment.

[0007] Patent document 4 describes an onium salt using fluorobenzenesulfonic acid as an alternative to PFAS. Photoacid generators having a fluorobenzenesulfonic acid structure do not contain fluoroalkanesulfonic acid in their structure, thus reducing their impact on health and the environment. Electron-withdrawing groups can increase the acid strength of sulfonic acid, but photoacid generators containing benzenesulfonic acid have low solubility in organic solvents, resulting in a high risk of defects due to precipitation from the resist casting solvent and defects during development.

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

[0009] [Patent Document 1] Japanese Patent Publication No. 2015-117200 [Patent Document 2] Japanese Patent Publication No. 2018-5224 [Patent Document 3] Japanese Patent Publication No. 2018-197853 [Patent Document 4] Japanese Patent 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 Publication No. 2018-049177 [Patent Document 10] Japanese Patent Publication No. 2015-4967 [Patent Document 11] International Publication No. 2024 / 225059 [Patent Document 12] Japanese Patent Publication No. 2025-79775 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] In acid-catalyzed chemically amplified resist compositions, there is a need for the development of resist compositions that offer even higher sensitivity, improve lithography performance such as LWR, CDU, exposure margin (EL), depth of field (DOF), and mask dimension dependence (MEEF), and exhibit excellent etching resistance after pattern formation.

[0011] The present invention has been made in view of the above circumstances, and aims to provide an onium salt used in a chemically amplified resist composition that is highly sensitive and has excellent lithography performance such as CDU and LWR in photolithography using high-energy rays, a photoacid generator consisting of the onium salt, a chemically amplified resist composition containing the photoacid generator, and a method for forming a pattern using the chemically amplified resist composition. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides: The present invention provides an onium salt that is represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is an integer of 0 or 1.] R 1is independently any one of a hydrogen atom, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom, and an electron-withdrawing group. The electron-withdrawing group is a halogen atom excluding a fluorine atom, a cyano group, a nitro group, and a hydrocarbyloxy group, a hydrocarbylthio group, a hydrocarbylcarbonyl group, a hydrocarbyloxycarbonyl group, a hydrocarbylcarbonyloxy group, a hydrocarbylsulfonyl group, or a hydrocarbyloxysulfonyl group having 1 to 20 carbon atoms which may contain a hetero atom. The said R 1 at least one of them is the said electron-withdrawing group. L A and L B are independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond or a carbamate bond. W 1 is a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. W 2 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hetero atom. W 1 and W 2 at least one of them has an aromatic ring. Also, in the formula (W 2 -[L A -W 1 m2 -L B -), the moiety shown has at least two iodine atoms directly bonded to the aromatic ring. 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).

Chemical formula

[0013] Such an onium salt is used in chemically amplified resist compositions that exhibit excellent solvent solubility, high sensitivity, and high contrast, as well as superior lithography performance such as CDU, MEEF, LWR, EL, and DOF, particularly in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV, and is also resistant to pattern deformation during fine pattern formation.

[0014] Furthermore, it is preferable that the onium salt of the present invention is such that the α-position of the sulfonic acid is substituted with the electron-withdrawing group.

[0015] In this case, it is preferable that the electron-withdrawing group is a cyano group or a nitro group.

[0016] The onium salt of the present invention exhibits particularly high sensitivity in such cases.

[0017] Furthermore, the onium salt of the present invention is (W in the above formula) 2 -[L A -W 1 ] m2 -L B The portion indicated by -) preferably has two or three iodine atoms directly bonded to the aromatic ring.

[0018] With such properties, the onium salt of the present invention exhibits high EUV absorption, improved sensitivity, and excellent solvent solubility.

[0019] Furthermore, the onium salt of the present invention is (W in the above formula) 2 -[L A -W 1 ] m2 -L BThe portion indicated by -) preferably has a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

[0020] Having such a structure increases the rigidity of the molecule, further reducing acid diffusion and improving LWR (low wave resistance).

[0021] Furthermore, the onium salt of the present invention has m2 = 1 and W 1 It has an alicyclic structure, and the W 2 This can be a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

[0022] Alternatively, the above m2 is 0, and the above W 2 This may be a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

[0023] Alternatively, the above m2 is 1, and the above W 1 It has a structure in which two or more iodine atoms are directly bonded to one aromatic ring, and the W 2 It may have an aromatic ring.

[0024] By adopting this structure, the onium salt of the present invention can more fully exhibit the effects of the present invention.

[0025] Furthermore, the onium salt of the present invention is preferably represented by the following general formula (A2). [ka] (In the formula, m1, L B , R 1 and Z + The same as above. m3 is an integer from 2 to 5, and m4 is an integer from 0 to 3. R 3This refers to a halogen atom, a nitro group, a hydroxyl group, a cyano group, a pentafluorosulfanyl group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom.

[0026] The onium salt of the present invention is more preferably represented by the following general formula (A3). [ka] (In the formula, m3, m4, L B , R 1 , R 3 , and Z + The same as above. m5 is an integer from 0 to 3. R 4 R 1 (Same as above.)

[0027] The onium salt of the present invention can exhibit the effects of the present invention more fully when it has such a structure.

[0028] Furthermore, the present invention provides a photoacid generator comprising the above-mentioned onium salt.

[0029] The photoacid generator of the present invention is particularly useful in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV, as it exhibits excellent solvent solubility, high sensitivity, high contrast, and superior lithography performance such as CDU, MEEF, LWR, EL, and DOF, and is also resistant to pattern deformation during fine pattern formation in chemically amplified resist compositions.

[0030] Furthermore, the present invention provides a chemically amplified resist composition characterized by containing the above-mentioned photoacid generator.

[0031] Such a chemically amplified resist composition exhibits excellent solvent solubility, high sensitivity, and high contrast, as well as superior lithography performance in areas such as CDU, MEEF, LWR, EL, and DOF, particularly in photolithography using high-energy beams like KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV. It also provides strong resistance to pattern deformation during fine pattern formation.

[0032] Furthermore, it is preferable that the chemically amplified resist composition of the present invention further includes a base polymer.

[0033] Furthermore, it is preferable that the base polymer contains repeating units represented by the following formula (b1) or (b2). [ka] (In the formula, R A Each of these is independently either a hydrogen atom or a methyl group. Y 1 This is a C1-C12 linking group containing a single bond, a phenylene group or a naphthylene group, or at least one 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 selected from a hydroxyl group, a halogen atom, a C1-C8 saturated hydrocarbyloxy group and a C2-C8 saturated hydrocarbylcarbonyloxy group. Y 2 These are single bonds or ester bonds. Y 3 These are single bonds, ether bonds, or ester bonds. R 11 and R 12 These are, independently, acid-unstable groups. R 13 This is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbyl carbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R 14This is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one selected from a hydroxyl 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 between 0 and 4.

[0034] The chemically amplified resist composition of the present invention typically comprises a base polymer.

[0035] Furthermore, the chemically amplified resist composition of the present invention may further contain at least one selected from an organic solvent, a quencher, a surfactant, and a dissolution inhibitor.

[0036] The chemically amplified resist composition of the present invention may optionally contain such components in addition to the base polymer described above.

[0037] Furthermore, in this invention, The present invention provides a pattern formation method comprising the steps of: forming a resist film on a substrate using the above-mentioned chemically amplified resist composition; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer solution.

[0038] By using the chemically amplified resist composition of the present invention, particularly in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beams (EB), and EUV, the resist composition exhibits excellent solvent solubility, high sensitivity, high contrast, and superior lithography performance in areas such as CDU, MEEF, LWR, EL, and DOF, as well as robust resistance to pattern deformation during fine pattern formation.

[0039] Furthermore, it is preferable that the high-energy beam be KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

[0040] In the pattern formation method of the present invention, such high-energy rays can be used particularly suitably. [Effects of the Invention]

[0041] The photoacid generator comprising the onium salt of the present invention is highly sensitive because the vicinity of the sulfonate anion is substituted with an electron-withdrawing group, and it is an environmentally friendly material because it does not contain fluorine atoms. Furthermore, the photoacid generator comprising the onium salt of the present invention has at least two iodine atoms directly bonded to the aromatic ring, resulting in high EUV absorption and improved sensitivity. This makes it possible to improve lithography performance such as CDU, MEEF, LWR, EL, and DOF. [Modes for carrying out the invention]

[0042] As described above, in photolithography using high-energy rays, there has been a need for the development of onium salts used in chemically amplified resist compositions that are highly sensitive and have excellent lithographic performance such as CDU and LWR, photoacid generators made from said onium salts, chemically amplified resist compositions containing said photoacid generators, and pattern formation methods using said chemically amplified resist compositions.

[0043] As a result of diligent research to achieve the above objective, the present inventors have discovered that by using an onium salt having a structure in which the vicinity of the sulfonate anion is substituted with a predetermined electron-withdrawing group and has at least two iodine atoms directly bonded to the aromatic ring as a photoacid generator, a chemically amplified resist composition that is highly sensitive in photolithography using high-energy rays and has excellent lithographic performance such as CDU, MEEF, and LWR can be obtained, thus completing the present invention.

[0044] In other words, the present invention is an onium salt, which is represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is an integer of 0 or 1.] R 1 Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R 1 At least one of them is the aforementioned electron-withdrawing group. L A and L B Each of these is independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a 1-10 carbon dioxide hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. W 1 This is a hydrocarbylene group having 1 to 40 carbon atoms, which may contain heteroatoms, and W 2 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms, and W 1 and W 2 At least one of them has an aromatic ring. Also, (W in the formula 2 -[L A -W 1 ] m2 -L B The portion indicated by -) has at least two iodine atoms directly bonded to the aromatic ring. Z + This 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 ~Rct5 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0045] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0046] [Onium salt] The onium salt of the present invention is represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is an integer of 0 or 1.] R 1 Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R 1 At least one of them is the aforementioned electron-withdrawing group. L A and L B Each of these is independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a 1-10 carbon dioxide hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. W 1This is a hydrocarbylene group having 1 to 40 carbon atoms, which may contain heteroatoms, and W 2 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms, and W 1 and W 2 At least one of them has an aromatic ring. Also, (W in the formula 2 -[L A -W 1 ] m2 -L B The portion indicated by -) has at least two iodine atoms directly bonded to the aromatic ring. Z + This 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 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0047] <Anion part> As represented by general formula (A), the onium salt of the present invention has a sulfonate ion (SO3) in the anionic portion. - The anion has a sulfonic acid ion, the vicinity of which is substituted with at least one electron-withdrawing group, and at least two iodine atoms directly bonded to the aromatic ring. The anion portion will be described in detail below.

[0048] In general formula (A), m1 is an integer between 1 and 4. m1 is preferably between 1 and 2, and more preferably 1. In this case, the mobility of the sulfonate anion is reduced, and acid diffusion can be suppressed.

[0049] In general formula (A), R 1is, independently of each other, any one of a hydrogen atom, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom excluding a fluorine atom, a cyano group, a nitro group, and a hydrocarbyloxy group, a hydrocarbylthio group, a hydrocarbylcarbonyl group, a hydrocarbyloxycarbonyl group, a hydrocarbylcarbonyloxy group, a hydrocarbylsulfonyl group, and a hydrocarbyloxysulfonyl group having 1 to 20 carbon atoms which may contain a heteroatom, and the above R 1 At least one of them is the above electron-withdrawing group. By substituting the vicinity of the sulfonate anion with an electron-withdrawing group other than a fluorine atom, it is possible to reduce the fluorine atom content of the photoacid generator and thus the resist composition while maintaining the acid strength of the photoacid generator, and the environmental load can be reduced.

[0050] As the electron-withdrawing group, those having a Hammett m-position substituent constant σ m in the Hammett's rule described in Chem. Rev. 1991, 91, 165-169 greater than 0 are preferred, those greater than 0.35 are more preferred, and a nitro group, a cyano group, a hydrocarbylcarbonyl group (particularly an acetyl group), a hydrocarbyloxycarbonyl group, and a hydrocarbylcarbonyloxy group are even more preferred, and a cyano group is most preferred. By bonding the electron-withdrawing group in the vicinity of the sulfonate anion, the acid strength of the sulfonic acid can be increased by the inductive effect. On the other hand, it is preferable that the electron-withdrawing group does not contain a group that becomes a hydrogen bond donor such as an amino group, a mercapto group, a carboxylic acid group, a sulfonic acid group, and an aldehyde group, and it is more preferable that these groups that become hydrogen bond donors do not substitute the α-position of the sulfonic acid. When these are present in the vicinity of the sulfonic acid, the nucleophilicity of the hydrogen bond donor from which the hydrogen atom has been abstracted by the sulfonate anion due to intramolecular hydrogen bonding increases, and the sensitivity decreases. The Hammett substituent constant σ of each group in this specification mThe values ​​used are those listed in Chem. Rev. 1991, 91, 165-169. For values ​​not listed, the difference between the pKa of benzoic acid and the pKa of a benzoic acid derivative with a substituent at the meta position is calculated using the software ACD / ChemSketch (ACD / Labs 8.00 Release Product Version: 8.08). m Find the value.

[0051] In particular, it is preferable that the α- or β-position of the sulfonic acid anion is substituted with an electron-withdrawing group, and more preferably that the α-position is substituted. In this case, the acid strength is highest and the sensitivity is highest. In particular, it is preferable that the α-position of the sulfonic acid is substituted with a cyano group or a nitro group.

[0052] More specifically, possible substitution locations for electron-withdrawing groups include, for example, (1) having only one electron-withdrawing group at the α-position of the sulfonate anion and no electron-withdrawing group at the β-position, (2) having two electron-withdrawing groups at the α-position of the sulfonate anion and no electron-withdrawing group at the β-position, (3) having only one electron-withdrawing group at the β-position of the sulfonate anion and no electron-withdrawing group at the α-position, and (4) having only one electron-withdrawing group at the α-position and only one electron-withdrawing group at the β-position. Note that if there are two or more electron-withdrawing groups, they may be the same or different.

[0053] The hydrocarbyl group, as well as the hydrocarbyl portion of the hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups 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 eicosyl groups; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, and 4-methyl groups. Examples include cyclic saturated hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups with 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups with 2 to 20 carbon atoms, such as phenyl and naphthyl; aralkyl groups with 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, or nitrogen atoms, and as a result, the material may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0054] Examples of halogen atoms other than fluorine atoms include chlorine atoms, bromine atoms, and iodine atoms.

[0055] L A and L B is, independently of each other, a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a C1-C10 hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond or a carbamate bond. L A As the ester bond (*-O-C(=O)-**, or *-C(=O)-O-**) is preferred, and the ester bond (*-C(=O)-O-**) is more preferred (* and ** are, respectively, the bond hands on the W 2 side and the SO 3- side). L B As the ester bond (*-O-C(=O)-**, or *-C(=O)-O-**) is preferred (* and ** are, respectively, the bond hands on the W 1 , and the SO 3- side).

[0056] In the general formula (A), m2 is 0 or 1.

[0057] W 1 is a C1-C40 hydrocarbylene group which may contain a heteroatom, and W 2 is a C1-C40 hydrocarbyl group which may contain a heteroatom, and at least one of W 1 and W 2 has an aromatic ring. Also, in the formula, the portion represented by (W 2 -[L A -W 1 ) m2 -L B -) has at least two iodine atoms directly bonded to the aromatic ring.

[0058] ​​​​​​​​​It may be included in both. The aromatic ring is (W 2 -[L A -W 1 ] m2 -L B It is sufficient for one or more of the elements indicated by -) to be included, and it is also acceptable for two or more, or three or more, to be included.

[0059] The aromatic ring is not particularly limited and can be a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, etc., but a benzene ring is preferred. It is preferable that two or three iodine atoms are bonded to the aromatic ring (or at least one aromatic ring if there are two or more aromatic rings). The aromatic ring may also have substituents other than iodine atoms, and these substituents are not particularly limited but can be hydroxyl groups, alkoxy groups such as methoxy groups, nitro groups, fluorine atoms, chlorine atoms, bromine atoms and other halogen atoms, etc. For example, an aromatic ring substituted with iodine atoms may be further substituted with substituents other than iodine atoms. On the other hand, if there are two or more aromatic rings, in addition to the aromatic ring to which iodine atoms are directly bonded, there may also be other aromatic rings that are unsubstituted or substituted with substituents other than iodine atoms (aryl groups, arylene groups).

[0060] The onium salt of the present invention is (W) in the formula. 2 -[L A -W 1 ] m2 -L B The portion indicated by -) has at least two iodine atoms directly bonded to the aromatic ring, resulting in high EUV absorption and good sensitivity. Furthermore, (W 2 -[L A -W 1 ] m2 -L B The portion indicated by -) preferably has two or three iodine atoms directly bonded to the aromatic ring. In this case, it exhibits high EUV absorption and sensitivity, while also having good solvent solubility.

[0061] Also, (W in the formula 2 -[L A -W 1] m2 -L B The portion indicated by -) preferably has a structure in which two or more iodine atoms are directly bonded to one aromatic ring. The onium salt of the present invention may have a structure in which two or more aromatic rings each have only one iodine atom, but a structure in which two or more iodine atoms are directly bonded to one aromatic ring is preferred because it increases the rigidity of the molecule, reduces acid diffusion, and improves the LWR.

[0062] W 1 is a hydroxylene group having 1 to 40 carbon atoms, which may contain heteroatoms, and may also be a group containing an aromatic ring as described above, or W 1 This may be a linear, branched, or cyclic alkylene or alkenylene group having 1 to 40 carbon atoms, which may contain heteroatoms and not have an aromatic ring. 2 This is a 1-40 carbon hydrocarbyl group which may contain heteroatoms, and may also be a group containing an aromatic ring as described above, or W 2 This may be a linear, branched, or cyclic alkyl or alkenyl group having 1 to 40 carbon atoms, which may contain heteroatoms and not have an aromatic ring. Examples of the heteroatoms include oxygen atoms, nitrogen atoms, sulfur atoms, etc. However, W 1 and W 2 At least one of them has an aromatic ring.

[0063] W 1 and W 2 The group may have an alicyclic structure, particularly one that does not have an aromatic ring and has an alicyclic structure. Examples of such alicyclic structures include alicyclic rings having 3 to 40 carbon atoms, preferably 3 to 10 carbon atoms, and particularly cyclohexane rings, norbornane rings, adamantane rings, 7-oxabicyclo[2.2.1]heptane, 7-thiabicyclo[2.2.1]heptane, and lactone rings. The alicyclic ring may have heteroatoms, and examples of such heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0064] W 1Specific examples include phenylene groups, mono-, di-, and tri-iodophenylene groups, and groups in which these groups are further substituted with substituents other than the iodine atom mentioned above; cyclohexanediyl groups, norbornanediyl groups, adamantanediyl groups, 7-oxabicyclo[2.2.1]heptanediyl groups, 7-thiabicyclo[2.2.1]heptanediyl groups, and lactonediyl groups; and linear alkylene or alkenylene groups having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, wherein the methylene group constituting the group may be substituted with an oxygen atom, and so on.

[0065] W 2 Specific examples include phenyl groups, mono-, di-, and tri-iodophenyl groups, and groups in which these groups are further substituted with substituents other than the iodine atom mentioned above; cyclohexyl groups, norbornyl groups, adamantyl groups, 7-oxabicyclo[2.2.1]heptyl groups, 7-thiabicyclo[2.2.1]heptyl groups, and monovalent groups obtained by removing one hydrogen atom from a lactone; and linear alkyl or alkenyl groups having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, wherein the methylene group constituting the group may be substituted with an oxygen atom; and monovalent groups obtained by removing one hydrogen atom from 9,10-ethano-9,10-dihydroanthracene, etc.

[0066] More specifically, the onium salt of the present invention preferably has the following structure.

[0067] The onium salt of the present invention has m2 = 1 and W 1 It has an alicyclic structure, and the W 2 The compound can have a structure in which two or more iodine atoms are directly bonded to one aromatic ring. In this case, in addition to the effects described above, the presence of an alicyclic structure provides appropriate solubility in polar solvents, improving the elution rate during TMAH development and thus improving the CDU. Examples of alicyclic structures include those exemplified above, but a lactone structure is preferred.

[0068] The onium salt of the present invention has m2 = 0 and W 2The structure can have two or more iodine atoms directly bonded to a single aromatic ring. In the case of such a structure, the effects of the present invention can be obtained more reliably, and in particular, by introducing substituents with lone pairs of electrons, such as methoxy or nitro groups, to the aromatic ring to which two iodine atoms are directly bonded, the acid can be quenched and LWR and CDU can be improved.

[0069] The onium salt of the present invention has m2 = 1 and W 1 It has a structure in which two or more iodine atoms are directly bonded to one aromatic ring, and the W 2 The compound may have an aromatic ring. In this case, in addition to the effects described above, having multiple aromatic rings reduces molecular diffusion and further improves LWR, which is preferable. In this case, the W 2 The aromatic ring may be an aromatic ring to which an iodine atom is directly bonded, an unsubstituted aromatic ring, or an aromatic ring substituted with substituents other than an iodine atom.

[0070] Furthermore, the onium salt of the present invention is preferably represented by the following general formula (A2). [ka] (In the formula, m1, L B , R 1 and Z + The same as above. m3 is an integer from 2 to 5, and m4 is an integer from 0 to 3. R 3 This refers to a halogen atom, a nitro group, a hydroxyl group, a cyano group, a pentafluorosulfanyl group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom.

[0071] The onium salt of the present invention is more preferably represented by the following general formula (A3). [ka] (In the formula, m3, m4, L B , R 1 , R 3 , and Z + The same as above. m5 is an integer from 0 to 3. R 4 R 1 (Same as above.)

[0072] Specific examples of anions of onium salts represented by general formula (A) are shown below, but are not limited to these. Furthermore, the bonding positions of the various substituents on the aromatic ring may be interchanged.

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] <Cation portion> In general formula (A), Z + This 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]

[0086] In general formulas (Z-1) and (Z-2), R ct1 ~R ct5 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom.

[0087] R ct1 ~R ct5 Specific examples of halogen atoms represented by include fluorine, chlorine, bromine, and iodine atoms.

[0088] R ct1 ~R ct5The hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C30 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups; C3-C30 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C30 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C30 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; C6-C30 aryl groups such as phenyl, naphthyl, and thienyl groups; C7-C30 aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, but aryl groups are preferred. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, nitrogen, and halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, and nitrogen atoms, and as a result, it may contain a hydroxyl group, fluorine atom, chlorine atom, bromine atom, iodine atom, cyano group, nitro group, carbonyl group, ether bond, ester bond, sulfonic acid ester bond, carbonate bond, lactone ring, sultone ring, carboxylic acid anhydride (-C(=O)-OC(=O)-), or haloalkyl group, etc.

[0089] Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, specific examples of the structure of the ring include those represented by the following formula.

[0090] [ka] (In the formula, the dashed line represents R ct3 (This is a combination of the two.)

[0091] Specific examples of sulfonium cations represented by the general formula (Z-1) are listed below, but are not limited to these.

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101]

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[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126] [ka]

[0127] [ka]

[0128] Specific examples of iodonium cations represented by the general formula (Z-2) are listed below, but are not limited to these.

[0129] [ka]

[0130] [ka]

[0131] Specific examples of the onium salt monomer of the present invention include any combination of the aforementioned anion and cation.

[0132] The onium salt monomer of the present invention can be synthesized, for example, by a method similar to that of the polymerizable anion sulfonium salt described in Japanese Patent No. 5201363, but the method for producing the onium salt monomer of the present invention is not limited thereto.

[0133] [Photoacid Generator] The photoacid generator of the present invention comprises the onium salt of the present invention.

[0134] For the reasons explained above, such a photoacid generator of the present invention, when used in a chemically amplified resist composition catalyzed with an acid, exhibits excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby enabling the realization of a chemically amplified resist composition exhibiting excellent lithography performance.

[0135] [Chemically Amplified Resist Composition] The chemically amplified resist composition of the present invention is characterized by containing the photoacid generator of the present invention.

[0136] In the chemically amplified resist composition of the present invention, the amount of the photoacid generator of the present invention is not particularly limited, but for example, it can be 1 to 60 parts by mass, preferably 10 to 60 parts by mass, and more preferably 20 to 40 parts by mass, per 100 parts by mass of the base polymer described later.

[0137] Since such a chemically amplified resist composition of the present invention contains the photoacid generator of the present invention, it can exhibit excellent solvent solubility, high sensitivity, and high acid diffusion suppression ability, thereby demonstrating excellent lithography performance.

[0138] The chemically amplified resist composition of the present invention may further contain other components of the photoacid generator of the present invention. The following describes optional components of the chemically amplified resist composition of the present invention.

[0139] <Base polymer> The chemically amplified resist composition of the present invention may typically contain a base polymer.

[0140] For example, the chemically amplified resist composition of the present invention preferably further comprises a base polymer containing repeating units having acid-unstable groups.

[0141] Such chemically amplified resist compositions can become positive-type resist compositions.

[0142] In this case, the base polymer includes, but is not limited to, repeating units represented by, for example, formula (b1) or (b2) below. [ka] (In the formula, R A Each of these is independently either a hydrogen atom or a methyl group. Y 1 This is a C1-C12 linking group containing a single bond, a phenylene group or a naphthylene group, or at least one 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 selected from a hydroxyl group, a halogen atom, a C1-C8 saturated hydrocarbyloxy group and a C2-C8 saturated hydrocarbylcarbonyloxy group. Y 2 These are single bonds or ester bonds. Y 3 These are single bonds, ether bonds, or ester bonds. R 11 and R 12 These are, independently, acid-unstable groups. R 13 This is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbyl carbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R 14This is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one selected from the group consisting of a hydroxyl 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 between 0 and 4.

[0143] The repeating unit having an acid-unstable group is not particularly limited, but may be represented by the general formula (b1) or (b2) above, for example.

[0144] Specific examples of monomers that give repeating unit b1 are listed below, but are not limited to these. Note that in the following formula, R A and R 11 This is the same as described above.

[0145] [ka]

[0146] [ka]

[0147] Specific examples of monomers that give repeating unit b2 are listed below, but are not limited to these. Note that in the following formula, R A and R 12 This is the same as described above.

[0148] [ka]

[0149] R 11 or R 12 Various acid-unstable groups can be selected, but examples include those represented by the following formulas (AL-1) to (AL-3).

[0150] [ka] (In the equation, dashed lines represent connections.)

[0151] In equation (AL-1), b is 0, 1, 2, 3, 4, 5, or 6. L1 This refers to 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; a saturated hydrocarbyl group having 4 to 20 carbon atoms including an ether bond or an ester bond; or a group represented by formula (AL-3). A tertiary hydrocarbyl group refers to a group obtained by the removal of a hydrogen atom from a tertiary carbon atom of a hydrocarbon.

[0152] R L1 The tertiary hydrocarbyl group represented by may be saturated or unsaturated, and may be branched or cyclic. Specific examples include tert-butyl group, tert-pentyl group, 1,1-diethylpropyl group, 1-ethylcyclopentyl group, 1-butylcyclopentyl group, 1-ethylcyclohexyl group, 1-butylcyclohexyl group, 1-ethyl-2-cyclopentenyl group, 1-ethyl-2-cyclohexenyl group, and 2-methyl-2-adamantyl group. Specific examples of the trihydrocarbyl silyl group include trimethylsilyl group, triethylsilyl group, and dimethyl-tert-butylsilyl group. The saturated hydrocarbyl group containing the carbonyl group, ether bond, or ester bond may be linear, branched, or cyclic, but a cyclic form is preferred. Specific examples include the 3-oxocyclohexyl group, the 4-methyl-2-oxooxan-4-yl group, the 5-methyl-2-oxooxolan-5-yl group, the 2-tetrahydropyranyl group, and the 2-tetrahydrofuranyl group.

[0153] Specific examples of acid-unstable groups represented by formula (AL-1) include tert-butoxycarbonyl group, tert-butoxycarbonylmethyl group, tert-pentyloxycarbonyl group, tert-pentyloxycarbonylmethyl group, 1,1-diethylpropyloxycarbonyl group, 1,1-diethylpropyloxycarbonylmethyl group, 1-ethylcyclopentyloxycarbonyl group, 1-ethylcyclopentyloxycarbonylmethyl group, 1-ethyl-2-cyclopentenyloxycarbonyl group, 1-ethyl-2-cyclopentenyloxycarbonylmethyl group, 1-ethoxyethoxycarbonylmethyl group, 2-tetrahydropyranyloxycarbonylmethyl group, and 2-tetrahydrofuranyloxycarbonylmethyl group.

[0154] Furthermore, other acid-unstable groups represented by formula (AL-1) include those represented by the following formulas (AL-1)-1 to (AL-1)-10.

[0155] [ka] (In the equation, dashed lines represent connections.)

[0156] In equations (AL-1)-1 to (AL-1)-10, b is the same as described above. L8 Each of these is independently a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. L9 R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. L10 This 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.

[0157] In formula (AL-2), R L2 and R L3Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, cyclopentyl group, cyclohexyl group, 2-ethylhexyl group, and n-octyl group.

[0158] In formula (AL-2), R L4 This is a hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, which may contain heteroatoms. 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, some of which may be substituted with hydroxyl groups, alkoxy groups, oxo groups, amino groups, or alkylamino groups. Specific examples of such substituted saturated hydrocarbyl groups include those shown below.

[0159] [ka] (In the equation, dashed lines represent connections.)

[0160] R L2 and R L3 , R L2 and R L4 , or R L3 and R L4 These atoms may bond with each other to form a ring with the carbon atoms to which they are bonded, or with carbon atoms and oxygen atoms, in which case the R atoms involved in ring formation L2 and R L3 , R L2 and R L4 , or R L3 and R L4 Each of these is an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10. The number of carbon atoms in the ring obtained by bonding these is preferably 3 to 10, more preferably 4 to 10.

[0161] Specific examples of linear or branched acid-unstable groups represented by formula (AL-2) include, but are not limited to, those shown in formulas (AL-2)-1 to (AL-2)-69 below. In the formulas below, dashed lines represent bonds.

[0162] [ka]

[0163] [ka]

[0164] [ka]

[0165] [ka]

[0166] Specific examples of cyclic acid-unstable groups represented by formula (AL-2) include tetrahydrofuran-2-yl group, 2-methyltetrahydrofuran-2-yl group, tetrahydropyran-2-yl group, and 2-methyltetrahydropyran-2-yl group.

[0167] Furthermore, examples of acid-unstable groups include groups represented by the following formulas (AL-2a) or (AL-2b). The polymer may be intermolecularly or intramolecularly crosslinked by these acid-unstable groups.

[0168] [ka] (In the equation, dashed lines represent connections.)

[0169] In formula (AL-2a) or (AL-2b), R L11 and R L12Each of these is 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. Also, R L11 and R L12 These may bond with each other to form a ring with the carbon atoms to which they are bonded, in which case R L11 and R L12 These are, independently, alkanediyl groups having 1 to 8 carbon atoms. L13 Each of these is independently a saturated hydrocarbylene group having 1 to 10 carbon atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic. Each of c and d is independently an integer from 0 to 10, preferably 0, 1, 2, 3, 4, or 5, and e is an integer from 1 to 7, preferably 1, 2, or 3.

[0170] In formula (AL-2a) or (AL-2b), L A This is 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. Furthermore, some of the -CH2- atoms in these groups may be substituted with a group containing a heteroatom, and some of the hydrogen atoms in these groups may be substituted with a hydroxyl group, a carboxyl group, an acyl group, or a fluorine atom. A Preferred examples include saturated hydrocarbon groups such as saturated hydrocarbylene groups, trivalent saturated hydrocarbon groups, and tetravalent saturated hydrocarbon groups having 1 to 20 carbon atoms, and arylene groups having 6 to 30 carbon atoms. The saturated hydrocarbon groups may be linear, branched, or cyclic. B These are -C(=O)-O-, -NH-C(=O)-O-, or -NH-C(=O)-NH-.

[0171] Specific examples of crosslinked acetal groups represented by formula (AL-2a) or (AL-2b) include the groups represented by the following formulas (AL-2)-70 to (AL-2)-77.

[0172] [ka] (In the equation, dashed lines represent connections.)

[0173] In formula (AL-3), R L5 This is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. L6 and R L7 Each of these is independently a C1-C20 hydrocarbyl group, 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 include C1-C20 alkyl groups, C3-C20 cyclic saturated hydrocarbyl groups, C2-C20 alkenyl groups, C3-C20 cyclic unsaturated hydrocarbyl groups, and C6-C10 aryl groups. L5 and R L6 The pair, R L5 and R L7 A combination of, or R L6 and R L7 These pairs may bond with each other to form an alicyclic ring with 3 to 20 carbon atoms, together with the carbon atoms to which they are bonded.

[0174] Specific examples of the group represented by formula (AL-3) include tert-butyl group, 1,1-diethylpropyl group, 1-ethylnorbonyl group, 1-methylcyclopentyl group, 1-ethylcyclopentyl group, 1-isopropylcyclopentyl group, 1-methylcyclohexyl group, 2-(2-methyl)adamantyl group, 2-(2-ethyl)adamantyl group, and tert-pentyl group.

[0175] Furthermore, specific examples of the group represented by formula (AL-3) include the groups represented by the following formulas (AL-3)-1 to (AL-3)-22.

[0176] [ka] (In the equation, dashed lines represent connections.)

[0177] In equations (AL-3)-1 to (AL-3)-22, R L14 Each of these is 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 Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. L16 This is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Furthermore, a phenyl group is preferred as the aryl group. L18 This is a fluorine atom, an iodine atom, a nitro group, or a trifluoromethyl group. L19 Each of these is 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. f is 1, 2, 3, 4, or 5.

[0178] Furthermore, examples of acid-unstable groups include those represented by the following formulas (AL-3)-23 or (AL-3)-24. The polymer may be intramolecularly or intermolecularly crosslinked by these acid-unstable groups.

[0179] [ka] (In the equation, dashed lines represent connections.)

[0180] In equations (AL-3)-23 and (AL-3)-24, R L14 This is the same as above. R L20 is a saturated or unsaturated hydrocarbylene group with 1 to 20 carbon atoms and a (g+1) valence, or an arylene group with 6 to 20 carbon atoms and a (g+1) valence, and may contain heteroatoms such as oxygen, sulfur, and nitrogen atoms. The saturated or unsaturated hydrocarbylene group may be linear, branched, or cyclic. g is 1, 2, or 3.

[0181] In addition to these acid-unstable groups, aromatic group-containing acid-unstable groups described in Japanese Patent Publication No. 5565293, Japanese Patent Publication No. 5434983, Japanese Patent Publication No. 5407941, Japanese Patent Publication No. 5655756, and Japanese Patent Publication No. 5655755 can also be used.

[0182] The base polymer may further contain repeating units c containing a phenolic hydroxyl group as an adhesion group. Specific examples of monomers that give repeating units c are, but are not limited to, those listed below. In the following formula, R A This is the same as described above.

[0183] [ka]

[0184] The base polymer may further contain repeating units d as other adhesive groups, including hydroxyl groups other than phenolic hydroxyl groups, lactone rings, sultone rings, ether bonds, ester bonds, sulfonic acid ester bonds, carbonyl groups, sulfonyl groups, cyano groups, or carboxyl groups. Specific examples of monomers that give repeating units d are listed below, but are not limited to these. In the following formula, R A This is the same as described above.

[0185] [ka]

[0186] [ka]

[0187] [ka]

[0188] [ka]

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] The base polymer may further contain repeating units e derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Specific examples of monomers that give repeating units e are listed below, but are not limited to these.

[0194] [ka]

[0195] The base polymer may further contain repeating units f derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindan, vinylpyridine, or vinylcarbazole.

[0196] The base polymer for the positive resist composition must include repeating units containing acid-labile groups, such as repeating unit b1 or b2. In this case, the content ratios of 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, and 0≦f≦0.7; and even 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.

[0197] On the other hand, the base polymer for the negative resist composition does not necessarily require an acid-labile group. Examples of such base polymers 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 even 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.

[0198] Examples of the method for synthesizing the base polymer include 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.

[0199] Specific examples of organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), methyl ethyl ketone (MEK), diethyl ether, and dioxane. Specific examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization temperature is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

[0200] When copolymerizing monomers containing hydroxyl groups, the hydroxyl groups may be substituted with acetal groups that are easily deprotected by acids such as ethoxyethoxy groups during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, they may be substituted with acetyl groups, formyl groups, or pivaloyl groups, and then subjected to alkaline hydrolysis after polymerization.

[0201] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and the acetoxy group may be deprotected by alkaline hydrolysis after polymerization to obtain hydroxystyrene or hydroxyvinylnaphthalene.

[0202] Ammonia water, triethylamine, etc., can be used as the base during alkaline hydrolysis. 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.

[0203] The weight-average molecular weight (Mw) of the polymer is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. Within this range, there is no risk of reduced etching resistance or loss of resolution due to insufficient contrast before and after exposure. In this invention, Mw is a polystyrene-converted value measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the solvent.

[0204] If the polymer has a broad molecular weight distribution (Mw / Mn), it may contain both low-molecular-weight and high-molecular-weight polymers, which may result in foreign matter being visible on the pattern or deterioration of the pattern shape after exposure. As the pattern rules become finer, the influence of Mw and Mw / Mn tends to increase. Therefore, to obtain a resist composition suitable for fine pattern dimensions, it is preferable that the Mw / Mn of the polymer be narrowly dispersed, between 1.0 and 2.0, and particularly between 1.0 and 1.5.

[0205] Furthermore, when the molecular weight distribution (Mw / Mn) of the base polymer is narrow, the presence of low-molecular-weight and high-molecular-weight polymers is suppressed, which can reduce the appearance of foreign matter on the pattern and the deterioration of the pattern shape after exposure. As the pattern rules become finer, the influence of Mw and Mw / Mn tends to increase. Therefore, to obtain a resist composition suitable for fine pattern dimensions, it is preferable that the Mw / Mn of the base polymer be narrowly dispersed, between 1.0 and 2.0, and particularly between 1.0 and 1.5.

[0206] The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw / Mn.

[0207] <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 is capable of dissolving the photoacid generator and each optional component of the present invention. 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] to

[0145] of Japanese Patent Application Publication 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 ether, ethylene glycol Examples include ethers such as monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters 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, and propylene glycol monotert-butyl ether acetate; and lactones such as γ-butyrolactone.

[0208] 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 as a mixture of two or more types.

[0209] <Fluorine atom-containing polymer> Furthermore, the chemically amplified resist composition of the present invention may further include a (D) fluorine atom-containing polymer comprising at least one selected from the group consisting of repeating units represented by the following general formula (D1), repeating units represented by the following general formula (D2), repeating units represented by the following general formula (D3), and repeating units represented by the following general formula (D4). [ka] (In the formula, R B This is either a hydrogen atom or a methyl group. R 21 and R 22 Each of these is independently either a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. R 23 This is a single-bonded, linear, or branched hydrocarbylene group having 1 to 5 carbon atoms. R 24 , R 25 and R 26 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, a C2-C15 acyl group, or an acid-unstable group. 24 , R 25 and R 26 When the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, some of these -CH2- groups may be substituted with ether bonds or carbonyl groups. R 27 This 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 between 1 and 3. X 21 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, or a phenylene bond. p is an integer, either 1 or 2. X 22 Each of these is independently a single bond or a hydroxylylene group having 1 to 20 carbon atoms when p is 1, and a trivalent hydrocarbon group having 1 to 20 carbon atoms when p is 2, and the hydroxylylene group and the trivalent hydrocarbon group may contain at least one selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a halogen atom. X 23 These are, independently, a single bond, an ester bond, an ether bond, an amide bond, a sulfonic acid ester bond, a urethane bond, a thiourethane bond, and a urea bond. Ar is a group derived from benzene or naphthalene. R 28Each of these is 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 hydroxyl group, a carboxyl group, a halogen atom, a cyano group, or a nitro group. m is an integer between 1 and 5.

[0210] The repeating units represented by formula (D1) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above.

[0211] [ka]

[0212] The repeating units represented by formula (D2) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above. [ka]

[0213] The repeating units represented by formula (D3) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above. [ka]

[0214] The repeating units represented by formula (D4) include, but are not limited to, the following. Note that in the following formula, R B This is the same as described above.

[0215] [ka]

[0216] The fluorine atom-containing polymer may further contain other repeating units other than those represented by any of the formulas (D1) to (D4). Specific examples of other repeating units include repeating units obtained from methacrylic acid or α-trifluoromethylacrylic acid derivatives. In the polymer-type surfactant, the content of the repeating units represented by formulas (D1) to (D4) is preferably 20 mol% or more, more preferably 60 mol% or more, and even more preferably 100 mol% of the total repeating units.

[0217] The Mw of the fluorine atom-containing polymer of component (D) is preferably 1,000 to 1,000,000, and more preferably 3,000 to 15,000. The Mw / Mn ratio is preferably 1.0 to 2.0, and more preferably 1.0 to 1.6.

[0218] A method for synthesizing the fluorine atom-containing polymer of component (D) is to heat a monomer that gives at least one selected from the repeating units represented by formula (D1), formula (D2), formula (D3), and formula (D4), and a monomer that gives other repeating units as needed, in an organic solvent with a radical initiator to carry out polymerization. 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 polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature for the polymerization reaction is preferably 50 to 100°C. The amount of these initiators added is preferably 0.01 to 25 mol% of the total amount of monomers to be polymerized. The reaction time is preferably 4 to 24 hours. The acid-unstable group may be used as is after being introduced into the monomer, or it may be protected or partially protected after polymerization. In addition, known chain transfer agents such as dodecyl mercaptan and 2-mercaptoethanol may be used to adjust the molecular weight during polymerization. In this case, the amount of chain transfer agent added is preferably in a molar ratio of 0.01 to 10 relative to the total monomer to be polymerized.

[0219] When the chemically amplified resist composition of the present invention contains a fluorine atom-containing polymer of component (D), its content is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 10 parts by mass, relative to 80 parts by mass of the base polymer of component (B). If 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, and defects due to residual water immersion and the elution of acid generators and quenchers can be suppressed. Furthermore, it becomes possible to adjust the solubility of the resist film surface, and a good CDU can be achieved. The fluorine atom-containing polymer (D) may be used alone or in combination of two or more types.

[0220] <Quencher> The chemically amplified resist composition of the present invention may optionally contain a quencher. In the present invention, a quencher means a compound that can prevent the diffusion of acid generated from the photoacid generator into unexposed areas by trapping the acid.

[0221] Specific examples of the quencher include amine compounds, sulfonates, or carboxylates. As the amine compound, primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103 are preferred, particularly amine compounds having any of the following: a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond. Compounds in which a primary or secondary amine is protected as a carbamate group, such as the compound described in Japanese Patent Publication No. 3790649, are also preferred. Such protected amine compounds are effective when there are components in the resist composition that are unstable to a base.

[0222] Specific examples of the sulfonate include the compound represented by the following formula (1). Furthermore, specific examples of the carboxylate include the compound represented by the following formula (2).

[0223] [ka]

[0224] In formula (1), R 101 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom, but SO3 - Excluding those in which the hydrogen atom bonded to the α-carbon atom of the group is substituted with a fluorine atom or a fluoroalkyl group.

[0225] R 101The C1-C40 hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C40 alkyl groups 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, tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbyl groups with 3 to 40 carbon atoms, such as decanyl group, adamantyl group, and adamantylmethyl group; alkenyl groups with 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 with 3 to 40 carbon atoms, such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (e.g., 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butyl group) Examples include aryl groups having 6 to 40 carbon atoms, such as phenyl groups and 4-n-butylphenyl groups, dialkylphenyl groups (e.g., 2,4-dimethylphenyl groups and 2,4,6-triisopropylphenyl groups), alkylnaphthyl groups (e.g., methylnaphthyl groups and ethylnaphthyl groups), and dialkylnaphthyl groups (e.g., 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.

[0226] 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, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl 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 sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), or a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include heteroaryl groups such as thienyl groups; alkoxyphenyl groups such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and 3-tert-butoxyphenyl groups; alkoxynaphthyl groups such as methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl, and n-butoxynaphthyl groups; dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl groups; and aryloxoalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl groups.

[0227] R 102 R is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms. 102 The hydrocarbyl group represented by R is 101 Examples of hydrocarbyl groups represented by the same formula as those exemplified above include the trifluoromethyl group, trifluoroethyl group, 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, and 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group, as well as fluorine-containing aryl groups such as pentafluorophenyl group and 4-trifluoromethylphenyl group.

[0228] Specific examples of sulfonate anions represented by formula (1) are listed below, but are not limited to these.

[0229] [ka]

[0230] [ka]

[0231] Specific examples of anions of carboxylate salts represented by formula (2) are listed below, but are not limited to these. In the following formulas, Me represents a methyl group.

[0232] [ka]

[0233] [ka]

[0234] [ka]

[0235] [ka]

[0236] [ka]

[0237] In equations (1) and (2), MQ +This is an onium cation. Examples of the onium cation include sulfonium cations, iodonium cations, and ammonium cations. The sulfonium cation is preferably represented by formula (Z-1), and specific examples include those similar to those exemplified as specific examples of sulfonium cations represented by formula (Z-1). The iodonium cation is preferably represented by formula (Z-2), and specific examples include those similar to those exemplified as specific examples of iodonium cations represented by formula (Z-2).

[0238] Another example of the aforementioned quencher is the polymer-type quencher described in Japanese Patent Publication No. 2008-239918. This enhances the rectangularity of the resist pattern by orientation on the resist surface. The polymer-type quencher also has the effect of preventing film erosion of the pattern and rounding of the pattern top when a protective film for immersion lithography is applied.

[0239] Furthermore, as a quencher, an onium salt having a sulfonium cation and a phenoxide anion moiety in the same molecule as described in Japanese Patent Publication No. 6848776, an onium salt having a sulfonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent Publication No. 6583136 and Japanese Patent Application Publication No. 2020-200311, or an onium salt having an iodonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent Publication No. 6274755 can also be used.

[0240] When the chemically amplified resist composition of the present invention contains a quencher, its content is preferably 0.001 to 12 parts by mass, and more preferably 0.01 to 8 parts by mass, per 80 parts by mass of the base polymer. The inclusion of a quencher facilitates the adjustment of the sensitivity of the resist film, suppresses acid diffusion in the resist film, improves resolution, suppresses sensitivity changes after exposure, reduces substrate and environmental dependence, and improves exposure margin and pattern profile. Furthermore, the addition of the quencher can also improve substrate adhesion. One type of quencher may be used alone, or two or more types may be used in combination.

[0241] <Surfactants> The chemically amplified resist composition of the present invention may further contain a surfactant.

[0242] Specific examples of the surfactants mentioned above include those described in paragraphs

[0165] to

[0166] of Japanese Patent Publication No. 2008-111103. By adding surfactants, the coatability of the resist composition can be further improved or controlled. When the resist composition of the present invention contains the surfactant, its content 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 in combination of two or more types.

[0243] <Other ingredients> In addition to the components described above, the chemically amplified resist composition of the present invention may also contain an acid generator (other acid generators), a dissolution inhibitor, a crosslinking agent, a water-repellency enhancer, or acetylene alcohols, etc.

[0244] Examples of the acid generator (other acid generators) include compounds that generate acid in response to active light or radiation (photoacid generators). Any compound that generates acid upon irradiation with high-energy rays can be used as a component of the photoacid generator, but acid generators that generate sulfonic acid, imido acid, or methidoic acid are preferred. Specific examples of suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, etc. Specific examples of the acid generators include those described in paragraphs

[0122] to

[0142] of Japanese Patent Publication No. 2008-111103, Japanese Patent Publication No. 2018-5224, and Japanese Patent Publication No. 2018-25789. When the resist composition of the present invention contains the acid generator, its content 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. Furthermore, since the onium salt of the present invention functions as a photoacid generator, it is not essential to separately incorporate the other acid generators mentioned above.

[0245] When the resist composition of the present invention is of the positive type, the difference in dissolution rate between the exposed and unexposed areas can be further increased by incorporating a dissolution inhibitor, thereby further improving the resolution. Specific examples of the dissolution inhibitor include compounds in which the hydrogen atoms of the phenolic hydroxyl groups of a compound having a molecular weight of preferably 100 to 1000, more preferably 150 to 800, and containing two or more phenolic hydroxyl groups in the molecule are substituted with acid-unstable groups in a total proportion of 0 to 100 mol%, or compounds in which the hydrogen atoms of the carboxyl groups of a compound containing a carboxyl group in the molecule are substituted with acid-unstable groups in an average total proportion of 50 to 100 mol%. Specifically, examples include compounds in which the hydrogen atoms of the hydroxyl group or carboxyl group of bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid are substituted with acid-unstable groups, as described, for example, in paragraphs

[0155] to

[0178] of Japanese Patent Application Publication No. 2008-122932.

[0246] When the chemically amplified resist composition of the present invention is of the positive type and contains the dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, and 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.

[0247] On the other hand, if the chemically amplified resist composition of the present invention is negative type, a negative type pattern can be obtained by adding a crosslinking agent to reduce the dissolution rate of the exposed area. Furthermore, the chemically amplified resist composition of the present invention can be negative type in organic solvent development even without the presence of a crosslinking agent.

[0248] Specific examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluryl compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds such as alkenyloxy groups, which are substituted with at least one group selected from methylol, alkoxymethyl, and acyloxymethyl groups. These may be used as additives or introduced as pendant groups into the polymer side chains. Compounds containing hydroxyl groups can also be used as crosslinking agents.

[0249] Specific examples of the epoxy compounds mentioned above include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0250] Specific examples of the melamine compounds include hexamethylmelamine, hexamethoxymethylmelamine, compounds in which 1 to 6 methylol groups of hexamethylmelamine are methoxymethylated or mixtures thereof, hexamethoxyethylmelamine, hexaacyloxymethylmelamine, and compounds in which 1 to 6 methylol groups of hexamethylmelamine are acyloxymethylated or mixtures thereof.

[0251] Specific examples of the guanamine compounds include tetramethylolguanamine, tetramethoxymethylguanamine, compounds in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated or mixtures thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, and compounds in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated or mixtures thereof.

[0252] Specific examples of the glycoluryl compounds include tetramethylol glycoluryl, tetramethoxy glycoluryl, tetramethoxymethyl glycoluryl, compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are methoxymethylated or mixtures thereof, and compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are asyloxymethylated or mixtures thereof. Specific examples of the urea compounds include tetramethylolurea, tetramethoxymethylurea, compounds in which 1 to 4 methylol groups of tetramethylolurea are methoxymethylated or mixtures thereof, and tetramethoxyethylurea.

[0253] Specific examples of the isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0254] Specific examples of the aforementioned azide compounds include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0255] Specific examples of compounds containing the aforementioned 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.

[0256] If the chemically amplified resist composition of the present invention is of the negative type and contains the crosslinking agent, the content of the crosslinking agent is preferably 0.1 to 50 parts by mass, and 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.

[0257] The water-repellent enhancer improves the water repellency of the resist film surface and can be used in immersion lithography without a topcoat. Preferred water-repellent enhancers include polymers containing alkyl fluoride, polymers containing 1,1,1,3,3,3-hexafluoro-2-propanol residues of a specific structure, and those exemplified in Japanese Patent Publication No. 2007-297590 and Japanese Patent Publication No. 2008-111103 are more preferred. The water-repellent enhancer needs to be soluble in an alkaline developer or an organic solvent developer. The aforementioned water-repellent enhancer having a specific 1,1,1,3,3,3-hexafluoro-2-propanol residue exhibits good solubility in the developer. As a water-repellent enhancer, polymers containing repeating units including amino groups or amine salts are highly effective in preventing acid evaporation in the PEB and thus preventing poor hole pattern opening after development. When the chemically amplified resist composition of the present invention contains the water-repellency improving agent, its content is preferably 0 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. The water-repellency improving agent may be used alone or in combination of two or more types. It may be used in this way.

[0258] Specific examples of the aforementioned acetylene alcohols include those described in paragraphs

[0179] to

[0182] of Japanese Patent Publication No. 2008-122932. When the chemically amplified resist composition of the present invention contains the aforementioned acetylene alcohols, the content is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The aforementioned acetylene alcohols may be used individually or in combination of two or more types.

[0259] [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 is a method that includes the steps of forming a resist film on a substrate using the chemically amplified resist composition of the present invention as described above, exposing the resist film with high-energy rays, and developing the exposed resist film using a developer. This example of a pattern formation method is the pattern formation method of the present invention.

[0260] With the pattern formation method of the present invention, since the chemically amplified resist composition of the present invention is used, pattern formation can be performed with excellent LWR, CDU, EL, DOF, MEEF, etc., i.e., with excellent lithography performance.

[0261] The pattern formation method of the present invention will be described in more detail below, but the pattern formation method of the present invention is not limited to the examples shown below.

[0262] First, the chemically amplified resist composition of the present invention is applied to a substrate for integrated circuit manufacturing (e.g., Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, and organic anti-reflective coatings, etc.) or a substrate for mask circuit manufacturing (e.g., Cr, CrO, CrON, MoSi2, and SiO2, etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, and doctor coating, so that the coating film thickness is preferably 0.01 to 2 μm. The resulting coating film is then pre-baked 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.

[0263] Next, the resist film is exposed using a high-energy beam. Specific examples of the high-energy beam include ultraviolet light, far-ultraviolet light, EB, EUV with wavelengths of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. For example, as the high-energy beam, an ArF excimer laser beam with a wavelength of 193 nm, a KrF excimer laser beam with a wavelength of 248 nm, an electron beam, or extreme ultraviolet light with wavelengths of 3 to 15 nm can be used. When using ultraviolet light, far-ultraviolet light, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, etc. as the high-energy beam, the exposure amount is preferably 1 to 200 mJ / cm², either directly or using a mask to form the desired pattern. 2 To the extent, more preferably 10 to 100 mJ / cm² 2 Irradiate to the extent of [a certain degree]. When using EB as the high-energy beam, the exposure dose is preferably 0.1 to 300 μC / cm². 2 To a degree, more preferably 0.5 to 200 μC / cm² 2 The pattern is drawn either directly or using a mask to form the desired pattern. The chemically amplified resist composition of the present invention is particularly suitable for fine patterning using high-energy rays, including KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, gamma rays, and synchrotron radiation, and is especially suitable for fine patterning using EB or EUV.

[0264] In addition to conventional exposure methods, immersion exposure can also be performed by interposing a liquid with a refractive index of 1.0 or higher between the resist film and the projection lens. In this case, a protective film insoluble in water can also be used.

[0265] The aforementioned water-insoluble protective film is used to prevent leaching from the resist film and to improve the water-repellent properties of the film surface, and there are two main types. One is an organic solvent-removable type that requires removal before alkaline aqueous solution development using an organic solvent that does not dissolve the resist film, and the other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with the soluble parts of the resist film. The latter is particularly preferably based on a polymer having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and soluble in alkaline developer, and dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof. Alternatively, the aforementioned water-insoluble and alkaline developer-soluble surfactant can be dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof.

[0266] After exposure, PEB may be performed on a hot plate or in an oven, preferably at 30-150°C for 10 seconds to 30 minutes, more preferably at 50-120°C for 30 seconds to 20 minutes, or PEB may not be performed at all.

[0267] After exposure or PEB, the resist film exposed to light is developed using a developer solution containing preferably 0.1 to 10% by mass, more preferably 2 to 5% by mass, of an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by conventional methods such as the dip method, puddle method, or spray method, thereby forming the desired pattern on the resist film. In the case of a positive-type chemically amplified resist composition, the parts irradiated with light dissolve in the developer solution, while the parts that were not exposed do not dissolve, and the desired positive-type pattern is formed on the substrate. In the case of a negative-type chemically amplified resist composition, the opposite is true: the parts irradiated with light become insoluble in the developer solution, while the parts that were not exposed dissolve.

[0268] Negative patterns can also be obtained by organic solvent development using a positive-type chemically amplified resist composition containing a base polymer with an acid-unstable group. Specific examples of developers used in this process 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 crotate, and ethyl crotate. Examples include 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 individually or in mixtures of two or more.

[0269] At the end of development, rinsing is performed. A solvent that mixes with the developer but does not dissolve the resist film is preferred as the rinsing solution. Preferred solvents include C3-C10 alcohols, C8-C12 ether compounds, C6-C12 alkanes, alkenes, alkynes, or aromatic solvents.

[0270] Specific examples of the C3-C10 alcohols 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. Examples include 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, and cyclohexanol, 1-octanol, etc.

[0271] Specific examples of the ether compounds having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, disec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0272] Specific examples of the C6-C12 alkanes include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Specific examples of the C6-C12 alkenes include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Specific examples of the C6-C12 alkynes include hexine, heptine, and octine.

[0273] Specific examples of the aromatic solvents mentioned above include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0274] Rinsing can reduce the occurrence of deformation and defects in the resist pattern. However, rinsing is not always necessary, and omitting it can reduce the amount of solvent used.

[0275] The developed hole patterns and trench patterns can also be shrunk using techniques such as thermal flow, RELACS, or DSA. A shrinking agent is applied to the hole pattern, and crosslinking of the shrinking agent occurs on the surface of the resist film due to the diffusion of an acid catalyst from the resist film during baking, causing the shrinking agent to adhere to the side walls 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, during which excess shrinking agent is removed and the hole pattern is reduced in size. [Examples]

[0276] The present invention will be specifically described below using synthesis examples, examples, and comparative examples, but the present invention is not limited to these. The following apparatus was used. • MALDI TOF-MS: S3000 manufactured by JEOL Ltd.

[0277] [1] Synthesis of onium salts [Synthesis Example 1-1] Synthesis of Onium Salt PAG-1 PAG-1 was synthesized according to the following reaction equation. [ka]

[0278] (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, the starting materials SM-1 (16.4g), oxanyl chloride (15.1g), DMF (N,N-dimethylformamide) (0.2g), and methylene chloride (100g) were added to the reaction vessel. The temperature in 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 removed by distillation to obtain a solid. The obtained solid was dissolved in methylene chloride (60g), and then the starting materials SM-2 (49.6g) and pyridine (3.1g) were added, and the mixture was cooled in an ice bath. After the addition, the temperature was raised to room temperature and aged for 24 hours. After aging, water was added to stop the reaction. Next, the mixture was treated with a normal aqueous system, and the solvent was removed by distillation. Subsequently, the residue was washed with diisopropyl ether to obtain 53.9g of intermediate In-1 as crystals (yield 84%).

[0279] (2) Synthesis of PAG-1 Under a nitrogen atmosphere, intermediate In-1 (53.9g), starting material SM-3 (53.6g), methylene chloride (100g), and water (50g) were mixed and stirred for 30 minutes. The organic layer was then separated, washed with water, and concentrated under reduced pressure. Diisopropyl ether (50g) was added to the concentrate, and crystallization was performed to obtain 69.3g of the target product, onium salt PAG-1, as white crystals (90% yield). The measurement results for the obtained onium salt PAG-1 are as follows. MALDI TOF-MS: POSITIVE M+ 425 (C 18 H 12 F2IS + equivalent) NEGATIVE M-492 (C9H4I2NO5S - equivalent)

[0280] [Synthesis Examples 1-2 to 1-10] Synthesis of Onium Salts PAG-2 to PAG-10 Using corresponding raw materials and known organic synthesis reactions, onium salts PAG-2 to PAG-10, represented by the following formulas, were synthesized.

[0281] [ka]

[0282] [ka]

[0283] [2] Synthesis of base polymers [Synthesis Examples 2-1 to 2-4] Synthesis of base polymers (polymers P-1 to P-4) Each monomer was combined and copolymerized in THF, a solvent. The mixture was then placed in methanol, and the precipitated solid was washed with hexane. After isolation and drying, base polymers (polymers P-1 to P-4) with the following compositions were obtained. The compositions of the obtained base polymers are: 1 Mw and Mw / Mn were confirmed by H-NMR using GPC (solvent: THF, standard: polystyrene).

[0284] [ka]

[0285] [3] Preparation and evaluation of chemically amplified resist compositions [Examples 1-1 to 1-13, Comparative Examples 1-1 to 1-6] (1) Preparation of chemically amplified resist composition A chemically amplified resist composition was prepared by dissolving a predetermined component selected from the onium salts (PAG-1 to PAG-10), comparative photoacid generators (cPAG-1 to cPAG-6), polymers (P-1 to P-4), and quencher (Q-1) of the present invention in a solvent containing 0.01% by mass of surfactant A (manufactured by Omnova) in the composition shown in Table 1 below, and filtering the solution through a 0.2 μm Teflon® filter.

[0286] In Table 1, the components are as follows: • Organic solvents: PGMEA (Propylene Glycol Monomethyl Ether Acetate) EL (Ethyl Lactate) DAA (Diacetone Alcohol)

[0287] Comparative photoacid generators: cPAG-1 to cPAG-6 [ka]

[0288] • Quencher: Q-1 [ka]

[0289] • Surfactant A: 3-methyl-3-(2,2,2-trifluoroethoxymethyl)oxetane-tetrahydrofuran-2,2-dimethyl-1,3-propanediol copolymer (manufactured by Omnova) [ka] a:(b+b'):(c+c')=1:4~7:0.01~1 (molar ratio) Mw=1500

[0290] (2) EUV Lithography Evaluation 1 Each resist material shown in Table 1 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43 mass%) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm. A resist film with a thickness of 50 nm was fabricated by pre-baking at 105°C for 60 seconds using a hot plate. The resist film was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, wafer-mounted dimension of 40 nm pitch, +20% bias hole pattern mask), and PEB was performed on a hot plate at the temperature shown in Table 1 for 60 seconds. Development was then performed with a 2.38 mass% TMAH aqueous solution for 30 seconds to form a hole pattern with dimensions of 20 nm.

[0291] Using a Hitachi High-Tech SEM (CG6300), the exposure amount at which a hole with a dimension of 20 nm was formed was measured and defined as the sensitivity. The dimensions of 50 holes at this point were then measured, and the CDU was calculated by taking three times the standard deviation (σ) from the results (3σ). The results are shown in Table 1.

[0292] [Table 1]

[0293] As shown in Table 1, the resist materials of the present invention, Examples 1-1 to 1-13, were found to have high sensitivity and good CDU. On the other hand, Comparative Example 1, which had a different structure near the sulfonate anion; Comparative Example 2, which had only one iodine atom directly bonded to the aromatic ring in a predetermined region; Comparative Example 3, which had a fluorine atom as an electron-withdrawing group; Comparative Example 4, which had only one iodine atom directly bonded to the aromatic ring in a predetermined region and no electron-withdrawing group; Comparative Example 5, which did not have an iodine atom directly bonded to the aromatic ring in a predetermined region; and Comparative Example 6, which had a carboxyl group (COOH) as an electron-withdrawing group, were unable to achieve both high sensitivity and CDU.

[0294] [Examples 2-1 to 2-13, Comparative Examples 2-1 to 2-6] (3) EUV lithography evaluation Each chemically amplified resist composition shown in Table 2 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm. The resist film was then pre-baked at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. The resist film was then exposed to an LS pattern with a 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), with exposure dose and focus varied (exposure dose pitch: 1 mJ / cm²). 2 The exposure was performed while adjusting the focus pitch (0.020 μm), and after exposure, PEB was performed for 60 seconds at the temperature shown in Table 2. Then, paddle development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution, rinsed with a surfactant-containing rinse material, and spin-dried to obtain a positive pattern. The obtained LS pattern was observed with a Hitachi High-Tech Corporation measuring SEM (CG6300), and the sensitivity and LWR were evaluated according to the method described below. The results are shown in Table 2.

[0295] [Sensitivity evaluation] The optimal exposure dose Eop(mJ / cm²) for obtaining an LS pattern with a line width of 18nm and a pitch of 36nm is obtained. 2 The value of ) was calculated and defined as the sensitivity. The smaller this value, the higher the sensitivity.

[0296] [LWR rating] The LS pattern obtained by irradiating with Eop was measured at 10 points along the longitudinal direction of the line, and the LWR was calculated as three times the standard deviation (σ) (3σ) from these results. The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0297] [Table 2]

[0298] As shown in Table 2, the resist materials of Examples 2-1 to 2-13 of the present invention exhibited high sensitivity and good LWR. On the other hand, Comparative Examples 2-1 to 2-6, which fall outside the scope of the present invention as described above, were unable to achieve both high sensitivity and good LWR.

[0299] This specification includes the following inventions:

[0300] [1]: An onium salt characterized by being represented by the following general formula (A). [ka] [In the formula, m1 is an integer between 1 and 4. m2 is an integer of 0 or 1.] R 1Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R 1 At least one of them is the aforementioned electron-withdrawing group. L A and L B Each of these is independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a 1-10 carbon dioxide hydrocarbylene group which may contain a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. W 1 This is a hydrocarbylene group having 1 to 40 carbon atoms, which may contain heteroatoms, and W 2 This is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms, and W 1 and W 2 At least one of them has an aromatic ring. Also, (W in the formula 2 -[L A -W 1 ] m2 -L B The portion indicated by -) has at least two iodine atoms directly bonded to the aromatic ring. Z + This 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 ct5Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0301] [2]: The onium salt according to [1] above, characterized in that the α-position of the sulfonic acid is substituted with the electron-withdrawing group.

[0302] [3]: The onium salt according to [1] or [2] above, characterized in that the electron-withdrawing group is a cyano group or a nitro group.

[0303] [4]: (W in the above formula) 2 -[L A -W 1 ] m2 -L B The onium salt according to any one of the above [1] to [3], characterized in that the portion indicated by -) has two or three iodine atoms directly bonded to the aromatic ring.

[0304] [5]: (W in the above formula) 2 -[L A -W 1 ] m2 -L B The onium salt according to any one of the above [1] to [4], characterized in that the portion indicated by -) has a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

[0305] [6]: The m2 is 1, and the W 1 It has an alicyclic structure, and the W 2 The onium salt according to any one of the above [1] to [5], characterized in that it has a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

[0306] [7]: When m2 is 0, W 2The onium salt according to any one of the above [1] to [5], characterized in that it has a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

[0307] [8]: The m2 is 1, and the W 1 It has a structure in which two or more iodine atoms are directly bonded to one aromatic ring, and the W 2 The onium salt according to any of the above [1] to [5], characterized in that it has an aromatic ring.

[0308] [9]: The onium salt described in any of [1] to [5] above, characterized in that it is represented by the following general formula (A2). [ka] (In the formula, m1, L B , R 1 and Z + The same as above. m3 is an integer from 2 to 5, and m4 is an integer from 0 to 3. R 3 This refers to a halogen atom, a nitro group, a hydroxyl group, a cyano group, a pentafluorosulfanyl group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom.

[0309]

[10] : The onium salt described in [9] above, characterized in that it is represented by the following general formula (A3). [ka] (In the formula, m3, m4, L B , R 1 , R 3 , and Z + The same as above. m5 is an integer from 0 to 3. R 4 R 1 (Same as above.)

[0310]

[11] : A photoacid generator characterized by comprising any of the onium salts described in [1] to

[10] above.

[0311]

[12] : A chemically amplified resist composition characterized by comprising the photoacid generator described in

[11] above.

[0312]

[13] : The chemically amplified resist composition according to

[12] , further characterized by comprising a base polymer.

[0313]

[14] : The chemically amplified resist composition according to

[13] above, characterized in that the base polymer contains repeating units represented by the following formula (b1) or (b2). [ka] (In the formula, R A Each of these is independently either a hydrogen atom or a methyl group. Y 1 This is a C1-C12 linking group containing a single bond, a phenylene group or a naphthylene group, or at least one 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 selected from a hydroxyl group, a halogen atom, a C1-C8 saturated hydrocarbyloxy group and a C2-C8 saturated hydrocarbylcarbonyloxy group. Y 2 These are single bonds or ester bonds. Y 3 These are single bonds, ether bonds, or ester bonds. R 11 and R 12 These are, independently, acid-unstable groups. R 13 This is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbyl carbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R 14This is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one selected from a hydroxyl 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 between 0 and 4.

[0314]

[15] : A chemically amplified resist composition according to any one of the above

[12] to

[14] , further comprising at least one selected from an organic solvent, a quencher, a surfactant, and a dissolution inhibitor.

[0315]

[16] : A pattern forming method comprising the steps of forming a resist film on a substrate using a chemically amplified resist composition described in any of

[12] to

[14] above, exposing the resist film with high-energy rays, and developing the exposed resist film using a developer.

[0316]

[17] : The pattern formation method according to

[16] above, characterized in that the high-energy beam is KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

[0317] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. An onium salt characterized by being represented by the following general formula (A). 【Chemistry 1】 [In the formula, m1 is an integer between 1 and 4. m2 is an integer of 0 or 1.] R １ Each of these is independently a hydrogen atom, a C1-C20 hydrocarbyl group which may contain a heteroatom, and an electron-withdrawing group, and the electron-withdrawing group is a halogen atom other than a fluorine atom, a cyano group, a nitro group, and a C1-C20 hydrocarbyloxy group, hydrocarbylthio group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, hydrocarbylsulfonyl group, and hydrocarbyloxysulfonyl group which may contain a heteroatom, and the R １ One of these is the aforementioned electron-withdrawing group. However, the α-position of the sulfonic acid is substituted with a cyano group or a nitro group. L Ａ and L Ｂ Each of these is a C1-C10 hydrocarbylene group which may independently contain a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, an oxalyl (-C(=O)C(=O)-) bond, or a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, or a carbamate bond. W １ is a hydrocarbylene group having 1 to 40 carbon atoms which may contain heteroatoms, and W ２ is a hydrocarbyl group having 1 to 40 carbon atoms which may contain heteroatoms, and W １ and W ２ at least one of them has an aromatic ring. Also, in the formula, the portion represented by (W ２ -[L Ａ -W １ ) ｍ２ -L Ｂ -) has at least two iodine atoms directly bonded to the aromatic ring. Z ＋ This 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 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ct1 and R ct2 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. However, the onium salt is The above m2 is 1, and the above W １ It has an alicyclic structure, and the W ２ Does it have a structure in which two or more iodine atoms are directly bonded to one aromatic ring? The above m2 is 0, and the above W ２ L is either a diiodophenyl group or a triiodophenyl group. Ｂ Each of these is independently a single bond, a carbonyl group, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a sulfonamide bond, a carbonate bond, a carbamate bond, or an oxalyl (-C(=O)C(=O)-) bond, and the R １ Each of these is independently either a hydrogen atom or an electron-withdrawing group, and the W ２ The aromatic ring may have substituents other than the iodine atom, and such substituents may be an alkoxy group, a nitro group, or a halogen atom. The above m2 is 1, and the above W １ It has a structure in which two or more iodine atoms are directly bonded to one aromatic ring, and the W ２ Does it have an aromatic ring? (W in the formula) ２ - [L Ａ -W １ ] ｍ２ -L Ｂ The part indicated by -) contains two or more aromatic rings, each containing only one iodine atom, or The above m2 is 1, and the above W １ The group is either a diiodophenylene group or a triiodophenylene group, and the diiodophenylene group and the triiodophenylene group may have substituents selected from a hydroxyl group, an alkoxy group, a nitro group, or a halogen atom. It is one of the following: However, the sulfonic acid anion portion of the onium salt may be any of the following formulas (T1) to (T9). 【Transformation 3】 (T1) 【Chemistry 4】 (T2) 【Transformation 5】 (T3) 【Transformation 6】 (T4) 【Transformation 7】 (T5) 【Transformation 8】 (T6) 【Chemistry 9】 (T7) 【Chemistry 10】 (T8) 【Chemistry 11】 (T9)

2. (W in the above formula) ２ - [L Ａ -W １ ] ｍ２ -L Ｂ The onium salt according to claim 1, characterized in that the portion indicated by -) has two or three iodine atoms directly bonded to the aromatic ring.

3. (W in the above formula) ２ - [L Ａ -W １ ] ｍ２ -L Ｂ The onium salt according to claim 1, characterized in that the portion indicated by -) has a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

4. The above m2 is 1, and the above W １ It has an alicyclic structure, and the W ２ The onium salt according to claim 3, characterized in that it has a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

5. The above m2 is 0, and the above W ２ The onium salt according to claim 3, characterized in that it has a structure in which two or more iodine atoms are directly bonded to one aromatic ring.

6. The above m2 is 1, and the above W １ It has a structure in which two or more iodine atoms are directly bonded to one aromatic ring, and the W ２ The onium salt according to claim 3, characterized in that it has an aromatic ring.

7. The onium salt according to claim 1, characterized in that it is represented by the following general formula (A2). 【Chemistry 12】 (In the formula, m1, L Ｂ , R １ and Z ＋ The same as above. m3 is an integer from 2 to 5, and m4 is an integer from 0 to 3. R ３ This refers to a halogen atom, a nitro group, a hydroxyl group, a cyano group, a pentafluorosulfanyl group, a C1-C20 hydrocarbyl group which may contain a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, or a C1-C20 hydrocarbylthio group which may contain a heteroatom.

8. The onium salt according to claim 7, characterized in that it is represented by the following general formula (A3). 【Chemistry 13】 (In the formula, m3, m4, L Ｂ , R １ , R ３ , and Z ＋ The same as above. m5 is an integer from 0 to 3. R ４ R １ (Same as above.)

9. A photoacid generator characterized by comprising an onium salt according to any one of claims 1 to 8.

10. A chemically amplified resist composition characterized by comprising the photoacid generator described in claim 9.

11. Furthermore, the chemically amplified resist composition according to claim 10, characterized in that it further contains a base polymer.

12. The chemically amplified resist composition according to claim 11, characterized in that the base polymer contains repeating units represented by the following formula (b1) or (b2). 【Chemistry 14】 (In the formula, R Ａ Each of these is independently either a hydrogen atom or a methyl group. Y １ This is a C1-C12 linking group comprising a single bond, a phenylene group or a naphthylene group, or at least one 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 selected from a hydroxyl group, a halogen atom, a C1-C8 saturated hydrocarbyloxy group and a C2-C8 saturated hydrocarbylcarbonyloxy group. Y ２ These are single bonds or ester bonds. Y ３ These are single bonds, ether bonds, or ester bonds. R １１ and R １２ These are, independently, acid-unstable groups. R １３ This is a saturated hydrocarbyl group having 1 to 4 carbon atoms, a halogen atom, a saturated hydrocarbyl carbonyl group having 2 to 5 carbon atoms, a cyano group, or a saturated hydrocarbyloxycarbonyl group having 2 to 5 carbon atoms. R １４ This is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and the alkanediyl group may contain at least one selected from a hydroxyl 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 between 0 and 4.)

13. The chemically amplified resist composition according to claim 11, further characterized by comprising at least one selected from an organic solvent, a quencher, a surfactant, and a dissolution inhibitor.

14. A pattern forming method characterized by comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition described in Claim 10; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.

15. The pattern formation method according to claim 14, characterized in that the high-energy beam is KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

Images