Sulfonium salts and acid generators comprising same

Abstract

Provided is a novel light-sensitive compound which quickly decomposes and generates an acid when irradiated with light having a wavelength of 20 nm or less. A sulfonium salt according to the present invention is represented by formula (1). In the formula, Rf1, Rf2, Rf11 and Rf12 may be the same or different and each represents a fluorine atom or a fluoroalkyl group. R1, R2, R3, R11, R12, R13, R21, R23, and R25 may be the same or different and each represents a hydrogen atom, a hydroxyl group, an alkyl group, or an iodine atom. R22 and R24 may be the same or different and each represents a hydrogen atom, a hydroxyl group, an alkyl group, an iodine atom, a fluorine atom or a fluoroalkyl group. And X-represents a monovalent counter anion. (In the formula, at least one element selected from the group consisting of R1, R2, R3, R11, R12, R13, and R21 to R25 represents an iodine atom. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a novel sulfonium salt, an acid generator containing the sulfonium salt, a photoresist containing the sulfonium salt, and a method for producing an electronic device using the photoresist. Background Art

[0002] Electronic devices are required to have a higher capacity and a smaller size, and to meet these requirements, semiconductor integrated circuits need to be made more dense and more highly integrated.

[0003] As a method for achieving high density and high integration of semiconductor integrated circuits, photolithography is known. Photolithography can be used to form fine patterns on semiconductors. In photolithography, first, a chemically amplified resist containing a photoacid generator and a resist is exposed, and the photoacid generator generates acid, and the solubility of the resist is changed by the acid to form a pattern. In addition, by shortening the wavelength of the exposure light, the pattern can be miniaturized.

[0004] As the above-mentioned photoacid generator, triphenylsulfonium salt is known (see Patent Document 1). The resist containing triphenylsulfonium salt can be processed with high precision by exposure using KrF excimer laser or ArF excimer laser. However, the above-mentioned resist has low sensitivity to light with a wavelength of less than 20nm such as EUV (extreme ultraviolet), EB (electron beam), and X-ray, and is difficult to use in lithography using EUV, etc.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-191741 Summary of the invention

[0008] Problems to be solved by the invention

[0009] Therefore, an object of the present invention is to provide a novel compound having photosensitive property which rapidly decomposes to generate an acid when irradiated with light having a wavelength of 20 nm or less.

[0010] Another object of the present invention is to provide an acid generator that efficiently generates an acid when irradiated with light having a wavelength of 20 nm or less.

[0011] Another object of the present invention is to provide a photoresist that can be used in photolithography using light having a wavelength of 20 nm or less.

[0012] Another object of the present invention is to provide a method for manufacturing an electronic device using the above-mentioned photoresist.

[0013] Means for solving problems

[0014] The present inventors have conducted intensive studies to solve the above problems and have found that the sulfonium salt represented by the following formula (1) has excellent sensitivity to light with a wavelength of 20 nm or less and is easily decomposed by irradiation with light of the above wavelength to generate an acid (H + X - ) (i.e., excellent acid production ability). The present invention was completed based on these findings.

[0015] That is, the present invention provides a sulfonium salt represented by the following formula (1).

[0016] [Chemistry 1]

[0017]

[0018] (Where Rf 1 , Rf 2 , Rf 11 and Rf 12 are the same or different and represent a fluorine atom or a fluoroalkyl group. 1 , R 2 , R 3 , R 11 , R 12 , R 13 , R 21 , R 23 and R 25 R is the same or different and represents a hydrogen atom, a hydroxyl group, an alkyl group or an iodine atom. 22 , R 24 are the same or different and represent a hydrogen atom, a hydroxyl group, an alkyl group, an iodine atom, a fluorine atom or a fluoroalkyl group. - represents a monovalent counter anion. 1 , R 2 , R 3 , R 11 , R 12 , R 13 and R 21 ~R 25 At least one of them represents an iodine atom. )

[0019] The present invention also provides the sulfonium salt described above, wherein the monovalent counter anion is a sulfonate anion or a nitrogen anion.

[0020] In addition, the present invention provides an acid generator comprising the above-mentioned sulfonium salt.

[0021] In addition, the present invention provides a photoresist comprising the above-mentioned acid generator and an acid-reactive compound.

[0022] Furthermore, the present invention provides a method for manufacturing an electronic device, the method comprising the step of performing patterning by photolithography using the above-mentioned photoresist.

[0023] Effects of the Invention

[0024] The sulfonium salt represented by the above formula (1) (hereinafter sometimes referred to as "sulfonium salt (1)") has excellent sensitivity to light with a wavelength of 20 nm or less, and can be easily decomposed by irradiation with light of the above wavelength to generate an acid (H + X - ). Therefore, if photolithography using light with a wavelength of 20 nm or less is performed using a photoresist containing a sulfonium salt (1), a fine pattern can be formed with high precision, and further capacity and size of electronic devices can be further increased. DETAILED DESCRIPTION

[0025] [Sulfonium salt]

[0026] The sulfonium salt (1) of the present invention is a compound represented by the following formula (1).

[0027] [Chemistry 2]

[0028]

[0029] (Where Rf 1 , Rf 2 , Rf 11 and Rf 12 are the same or different and represent a fluorine atom or a fluoroalkyl group. 1 , R 2 , R 3 , R 11 , R 12 , R 13 , R 21 , R 23 and R 25 R is the same or different and represents a hydrogen atom, a hydroxyl group, an alkyl group or an iodine atom. 22 , R 24 are the same or different and represent a hydrogen atom, a hydroxyl group, an alkyl group, an iodine atom, a fluorine atom or a fluoroalkyl group. - represents a monovalent counter anion. 1 , R 2 , R 3 , R 11 , R 12 , R 13 and R 21 ~R 25 At least one of them represents an iodine atom. )

[0030] The alkyl group is, for example, an alkyl group having 1 to 5 carbon atoms, and examples thereof include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, and pentyl. The alkyl group is preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably an alkyl group having 1 or 2 carbon atoms, from the perspective of easy raw material acquisition.

[0031] The fluoroalkyl group is a group in which at least one hydrogen atom of an alkyl group is substituted with a fluorine atom, and examples of the alkyl group include the same examples as those described above.

[0032] As the fluoroalkyl group, preferably, all hydrogen atoms of the alkyl group are substituted with fluorine atoms, that is, a perfluoroalkyl group (e.g., perfluoroC 1-5 alkyl).

[0033] In the above formula (1), R 1 , R 2 , R 3 , R 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 and R 25 At least one of the groups represented by represents an iodine atom. Among them, from the aspect of being easily decomposed by light irradiation to generate an acid (i.e., having excellent decomposition efficiency or excellent photosensitivity), a compound in which two or more of the groups selected from the above groups are iodine atoms is preferred, a compound in which three or more of the groups are particularly preferred, and a compound in which four or more of the groups are particularly preferred.

[0034] In the above formula (1), the position to which the iodine atom is bonded is not particularly limited. However, from the perspective of being easily decomposed by light irradiation to generate an acid (i.e., having excellent decomposition efficiency or excellent photosensitivity), a compound in which the iodine atom is bonded at the ortho position relative to the sulfur atom shown in formula (1) is preferred.

[0035] That is, in formula (1), it is preferably selected from the group consisting of 1 , R 3 , R 11 and R 13 The compound is one in which at least one of the groups represented by is an iodine atom, and more preferably a compound in which two or more of the groups represented by are iodine atoms.

[0036] Examples of the counter anion include halogen ions, halogen oxo acid anions, boron anions, phosphate anions, sulfate anions, sulfonate anions, nitrogen anions, carboxylate anions, methide anions, SbF6 - OH - 、SCN- 、NO2 - 、NO3 - wait.

[0037] Examples of the halogen ions include Cl - Br - ,I - wait.

[0038] The above-mentioned halogen oxygen-containing acid anions include, for example, ClO4 - IO3 - BrO3 - wait.

[0039] Examples of the boron anion include BF4 - Inorganic boron anions, (C6F5)4B - 、((CF3)2C6H3)4B - , tetraphenylborate, tetrakis(monofluorophenyl)borate, tetrakis(difluorophenyl)borate, tetrakis(trifluorophenyl)borate and other organic boron anions.

[0040] Examples of the phosphate anion include PF6 - PO4 3- Inorganic phosphate anions, (CF3CF2)3PF3 - 、(CF3CF2)2PF4 - 、(CF3CF2)PF5 - and other organophosphate anions.

[0041] The sulfonate anion is represented by, for example, the following formula (s1).

[0042] R s1 -SO3 - (s1)

[0043] (Where R s1 represents an organic group. )

[0044] As R s1 The organic group in the formula (a) may be a C 1-30 A hydrocarbon group, a heterocyclic group which may have a substituent, and two or more of the above groups are connected by a single bond or selected from -O-, -CO2-, -S-, -SO3- and -SO2N (R s2 )-The group connected by the connecting group. The above R s2 represents a hydrogen atom or an alkyl group (e.g. C 1-30 As the substituent, for example, a halogen atom such as a fluorine atom can be mentioned.

[0045] In the above C1-30 The hydrocarbon group contains C 1-30 Aliphatic hydrocarbon group, C 3-30 Alicyclic hydrocarbon group, C 6-30 An aromatic hydrocarbon group and a group in which two of them are bonded together.

[0046] As the above C 1-30 Hydrocarbyl, preferably C 1-30 Alkyl, C 6-15 Aryl, C 6-15 Cycloalkyl, C 6-15 A bridged cyclic hydrocarbon group and a group formed by bonding two of them.

[0047] The above-mentioned heterocyclic group is a group obtained by removing one hydrogen atom from the structural formula of a heterocycle. The above-mentioned heterocycle includes aromatic heterocycles and non-aromatic heterocycles. As such heterocycles, there can be mentioned 3-10 membered rings (preferably 4-6 membered rings) having carbon atoms and at least one hetero atom (for example, oxygen atoms, sulfur atoms, nitrogen atoms, etc.) among the atoms constituting the ring, and fused rings thereof.

[0048] As a specific example of the sulfonate anion, CH3SO3 can be cited. - 、C4H9SO3 - CF3SO3 - 、C2F5C4H4SO3 - 、C4F9SO3 - , benzenesulfonate anion, p-toluenesulfonate anion, camphorsulfonate anion.

[0049] Examples of the nitrogen anion include a sulfonyl imide anion represented by the following formula (n1).

[0050] (R n1 SO2)2N - (n1)

[0051] (In the formula, 2 R n1 The same or different, representing an organic group. )

[0052] As R n1 The organic group in R s1 The same example of organic groups in .

[0053] As a specific example of the above-mentioned nitrogen anion, (FSO2)2N - 、(CF3SO2)2N - 、(C4F9SO2)2N - 、(C2F5SO2)2N - wait.

[0054] The carboxylate anion is represented by, for example, the following formula (c1).

[0055] R c1 -COO - (c1)

[0056] (Where R c1 represents an organic group. )

[0057] As R c1 The organic group in R s1 The same example of organic groups in .

[0058] Specific examples of the carboxylate anion include CF3CO2 - 、CH3CO2 - 、C2H5CO2 - 、PhCO2 - wait.

[0059] Examples of the methide anion include a sulfonyl methide anion represented by the following formula (m1).

[0060] (R m1 SO2)3C - (m1)

[0061] (In the formula, 3 R m1 The same or different, representing an organic group. )

[0062] As R m1 The organic group in R s1 The same example of organic groups in .

[0063] Specific examples of the methide anion include (CF3SO2)3C - wait.

[0064] The counter anions include, in addition to the above, anions described in, for example, Japanese Patent Application Laid-Open Nos. 2013-47211, 2013-81708, 2013-80245, 2013-80240, and 2013-33161.

[0065] As the counter anion, a sulfonate anion or a nitrogen anion is preferred from the viewpoint of excellent solubility.

[0066] The sulfonium salt represented by the above formula (1) is preferably a sulfonium salt represented by the following formula (1a) or a sulfonium salt represented by the following formula (1b) because it is easily decomposed by light irradiation to generate an acid (that is, has excellent decomposition efficiency or excellent photosensitivity).

[0067] [Chemistry 3]

[0068]

[0069] In the above formula, Rf 31 , Rf 32 are the same or different and represent a fluorine atom or a fluoroalkyl group. 31 , R 32 and R 33 are the same or different and represent a hydrogen atom, a hydroxyl group, an alkyl group, or an iodine atom. 41 , R 42 , R 43 , R 44 and R 45 are the same or different and represent a hydrogen atom, a hydroxyl group, an alkyl group, or an iodine atom. - represents a monovalent counter anion.

[0070] It should be noted that the two aryl groups represented by brackets in the above formula (1a) may be the same or different. In addition, the three aryl groups represented by brackets in the above formula (1b) may be the same or different.

[0071] Furthermore, in formula (1a), two R 31 , 2 R 32 , 2 R 33 , R 41 , R 42 , R 43 , R 44 and R 45 At least one of them represents an iodine atom.

[0072] In addition, in formula (1b), three R 31 , 3 Rs 32 And 3 R 33 At least one of them represents an iodine atom.

[0073] As the sulfonium salt represented by the above formula (1a), the sulfonium salt represented by the following formula (1a-1) is preferred from the viewpoint that it is easily decomposed by light irradiation to generate an acid (i.e., it is excellent in decomposition efficiency or photosensitivity). As the sulfonium salt represented by the above formula (1b), the sulfonium salt represented by the following formula (1b-1) is preferred from the viewpoint that it is easily decomposed by light irradiation to generate an acid (i.e., it is excellent in decomposition efficiency or photosensitivity).

[0074] [Chemistry 4]

[0075]

[0076] In the above formula, Rf 31, Rf 32 are the same or different and represent a fluorine atom or a fluoroalkyl group. 31 '、R 33 '、R 41 '、R 42 '、R 43 '、R 44 ' and R 45 'same or different, represents a hydrogen atom or an iodine atom. - represents a monovalent counter anion.

[0077] It should be noted that the two aryl groups represented by brackets in the above formula (1a-1) may be the same or different. In addition, the three aryl groups represented by brackets in the above formula (1b-1) may be the same or different.

[0078] Furthermore, in formula (1a-1), two R 31 , 2 R 33 '、R 41 '、R 42 '、R 43 '、R 44 ' and R 45 At least one of ' represents an iodine atom.

[0079] In addition, in formula (1b-1), three R 31 ' and 3 R's 33 At least one of ' represents an iodine atom.

[0080] In the above formula, Rf 31 , Rf 32 Among them, a fluorine atom is preferred because of its particularly excellent decomposition efficiency.

[0081] In the above formula, about R 31 ' and R 33 ', wherein, from the perspective of particularly excellent decomposition efficiency, it is preferred that at least one represents an iodine atom.

[0082] In the above formula, R 41 '、R 42 '、R 43 '、R 44 ' and R 45 Among the groups represented by ', at least one preferably represents an iodine atom, and particularly preferably two or more selected from the above groups represent iodine atoms.

[0083] Specific examples of the sulfonium salt represented by the above formula (1a-1) include sulfonium salts represented by the following formulas (1a-1-1) to (1a-1-30). - Same as above.

[0084] [Chemistry 5]

[0085]

[0086] [Chemistry 6]

[0087]

[0088] [Chemistry 7]

[0089]

[0090] [Chemistry 8]

[0091]

[0092] Specific examples of the sulfonium salt represented by the above formula (1b-1) include sulfonium salts represented by the following formulas (1b-1-1) to (1b-1-12). - Same as above.

[0093] [Chemistry 9]

[0094]

[0095] [Chemistry 10]

[0096]

[0097] The sulfonium salt (1) has excellent solubility in organic solvents. Its solubility in an organic solvent (e.g., propylene glycol monomethyl ether acetate) at 25° C. is, for example, 2% by weight or more (e.g., 2 to 50% by weight), preferably 3% by weight or more, more preferably 4% by weight or more, and particularly preferably 5% by weight or more.

[0098] Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; carbonates such as propylene carbonate, ethylene carbonate, 1,2-butylene carbonate, dimethyl carbonate, and diethyl carbonate; chain or cyclic esters such as ethyl acetate, butyl acetate, and ethyl lactate, β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone; glycol diethers such as ethylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol dimethyl ether, triethylene glycol diethyl ether, and tripropylene glycol dibutyl ether; glycol monoether monoesters such as ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate; and ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone. These may be used alone or in combination of two or more.

[0099] Among them, the organic solvent preferably contains at least one selected from the group consisting of ketones, chain esters, and glycol monoether monoesters.

[0100] The sulfonium salt (1) is highly sensitive to light with a wavelength of 20 nm or less, such as EUV (extreme ultraviolet light), EB (electron beam), and X-ray. Moreover, even if no photosensitizer is used, light energy is directly transmitted to the sulfonium salt (1) and the sulfonium salt (1) is rapidly photodecomposed to generate acid (H + X - :X - Same as above).

[0101] Since the sulfonium salt (1) has the above-mentioned properties, it can be suitably used as an acid generator (for example, a photoacid generator).

[0102] The sulfonium salt represented by the formula (1a-1-22) among the sulfonium salts (1) can be produced, for example, by the following reaction. Sulfonium salts other than the sulfonium salt represented by the formula (1a-1-22) among the sulfonium salts (1) can also be produced by a method according to the following reaction.

[0103] [Chemistry 11]

[0104]

[0105] [Chemistry 12]

[0106]

[0107] In addition, the sulfonium salt represented by the formula (1a-1-3) among the above-mentioned sulfonium salts (1) can also be produced by, for example, the following reaction.

[0108] [Chemistry 13]

[0109]

[0110] In the above reaction formula, X - With X in formula (1) - MX represents a salt of an alkali metal (lithium, sodium, potassium, etc.) cation and a univalent counter anion. A represents a halogen atom, X' - Cl - or triflate anion.

[0111] In the above reaction formula, the dehydration condensation reaction can be carried out in the presence or absence of a solvent. When the dehydration condensation reaction is carried out in the presence of a solvent, for example, one or more solvents selected from acetonitrile, ethyl acetate, tetrahydrofuran, chloroform, dichloromethane, etc. can be used. The reaction temperature is about -20 to 150°C, although it depends on the boiling point of the solvent used. The reaction time is about 1 to several tens of hours.

[0112] In the above reaction formula, the Grignard reaction can be carried out in the presence or absence of a solvent. When the Grignard reaction is carried out in the presence of a solvent, a common solvent used in the Grignard reaction (for example, one or more solvents selected from diethyl ether, tetrahydrofuran, dichloromethane, etc.) can be used. The reaction temperature is about -20 to 150°C, although it also depends on the boiling point of the solvent used. The reaction time is about 1 to several tens of hours.

[0113] In the above reaction formula, the iodination reaction can be carried out using an iodizing agent such as iodine, iodine monochloride, potassium iodide, N-iodosuccinimide, etc. The iodination reaction can be carried out in the presence or absence of a solvent. When the iodination reaction is carried out in the presence of a solvent, for example, one or more solvents selected from acetonitrile, ethyl acetate, tetrahydrofuran, chloroform, dichloromethane, etc. can be used. The reaction temperature is, for example, about -20 to 80°C. The reaction time is about 1 to 48 hours.

[0114] The reaction atmosphere is not particularly limited as long as it does not inhibit the reaction, and may be, for example, air atmosphere, nitrogen atmosphere, argon atmosphere, etc. The reaction may be carried out by any method such as batch method, semi-batch method, or continuous method.

[0115] After the above reaction is completed, the obtained reaction product can be separated and purified by separation means such as filtration, concentration, distillation, extraction, crystallization, adsorption, recrystallization, column chromatography, or a combination of these separation means.

[0116] The chemical structure of the sulfonium salt of the present invention can be obtained, for example, by 1 H-, 11 B-, 13 C-, 19 F-, or 31 P-NMR spectrum, infrared absorption spectrum, or elemental analysis, etc.) for identification.

[0117] [Acid generator]

[0118] The acid generator of the present invention contains at least the sulfonium salt (1). The acid generator may contain one of the sulfonium salts (1) alone or two or more of them in combination. The acid generator may contain components other than the sulfonium salt (1), but the proportion of the sulfonium salt (1) relative to the total compounds (100% by weight) contained in the acid generator that generate an acid after decomposition upon light irradiation is, for example, preferably 50% by weight or more, more preferably 60% by weight or more, further preferably 70% by weight or more, particularly preferably 80% by weight or more, most preferably 90% by weight or more, and particularly preferably 95% by weight or more. That is, although an acid generator other than the sulfonium salt (1) may be contained, the content of the other acid generator relative to the total compounds (100% by weight) that generate an acid after decomposition upon light irradiation is, for example, preferably 50% by weight or less, more preferably 40% by weight or less, further preferably 30% by weight or less, particularly preferably 20% by weight or less, most preferably 10% by weight or less, and particularly preferably 5% by weight or less.

[0119] The acid generator has excellent solubility in an organic solvent. The amount of the acid generator (or the sulfonium salt (1)) dissolved in 100 parts by weight of the organic solvent at 25° C. is, for example, 5 parts by weight or more, preferably 10 parts by weight or more, particularly preferably 15 parts by weight or more, and most preferably 20 parts by weight or more. Examples of the organic solvent include the same organic solvents in which the sulfonium salt (1) is soluble.

[0120] The above-mentioned acid generator is excellently sensitive to light with a longer wavelength, and is also excellently sensitive to light with a wavelength of 20 nm or less. When irradiated with the above-mentioned light, it is easily decomposed to generate acid (H + X - ).

[0121] Since the acid generator has the above-mentioned characteristics, it can be suitably used as an acid generator for photoresists (particularly, an acid generator for photoresists used in photolithography using light having a wavelength of 20 nm or less).

[0122] [Photoresist]

[0123] The photoresist of the present invention comprises the above-mentioned acid generator (or the above-mentioned sulfonium salt (1)) and an acid-reactive compound.

[0124] The content of the acid generator (or the sulfonium salt (1)) is, for example, 0.001 to 20% by weight, preferably 0.01 to 15% by weight, and particularly preferably 0.05 to 7% by weight of the total amount of the acid-reactive compound.

[0125] When the content of the acid generator (or the sulfonium salt (1)) is 0.001 wt% or more of the total amount of the acid-reactive compound, excellent sensitivity can be exhibited not only to light with a longer wavelength, but also to light with a wavelength of 20 nm or less. In addition, when the content is 20 wt% or less of the total amount of the acid-reactive compound, the effect of improving the resolution of the photoresist can be obtained.

[0126] The acid-reactive compound is a compound whose solubility in an alkaline developer changes due to the action of an acid. The photoresist of the present invention may contain the acid-reactive compound alone or in combination of two or more thereof.

[0127] The acid-reactive compounds include compounds that are easily soluble in an alkaline developer and react with a crosslinking agent in the presence of an acid to generate a compound that is poorly soluble or insoluble in an alkaline developer; and compounds that are poorly soluble or insoluble in an alkaline developer and whose solubility in an alkaline developer is increased by the action of an acid.

[0128] Therefore, the above-mentioned photoresist includes the following composition (1) and composition (2).

[0129] Composition (1): a composition comprising the above-mentioned acid generator and a negative photosensitive resin (QN) which is easily soluble in an alkaline developer and generates a compound which is poorly soluble or insoluble in an alkaline developer in the presence of an acid;

[0130] Composition (2): A composition comprising the above-mentioned acid generator and a positive photosensitive resin (QP) which is poorly soluble or insoluble in an alkaline developer and whose solubility in the alkaline developer is increased by the action of an acid.

[0131] Examples of the negative photosensitive resin (or negative chemically amplified resin; QN) include a composition containing a phenolic hydroxyl group-containing resin (QN1) and a crosslinking agent (QN2).

[0132] The resin (QN1) containing a phenolic hydroxyl group is a resin containing a phenolic hydroxyl group which is easily soluble in an alkaline developer and is poorly soluble or insoluble in an alkaline developer after reacting with a crosslinking agent, and examples thereof include novolac resins, polyhydroxystyrene, copolymers of hydroxystyrene, copolymers of hydroxystyrene and styrene, hydroxystyrene, copolymers of styrene and (meth)acrylic acid derivatives, phenol-benzenedimethanol condensation resins, cresol-benzenedimethanol condensation resins, polyimides containing a phenolic hydroxyl group, polyamic acids containing a phenolic hydroxyl group, phenol-dicyclopentadiene condensation resins, etc. These may be used alone or in combination of two or more.

[0133] The phenolic hydroxyl group-containing resin (QN1) may contain a phenolic low-molecular compound as part of its components.

[0134] The polystyrene-equivalent weight average molecular weight (Mw) of the phenolic hydroxyl group-containing resin (QN1) measured by GPC is, for example, 2,000 to 20,000.

[0135] The crosslinking agent (QN2) is, for example, a compound that can crosslink the resin (QN1) containing a phenolic hydroxyl group by using an acid generated from an acid generator, and examples thereof include bisphenol A-based epoxy compounds, bisphenol F-based epoxy compounds, bisphenol S-based epoxy compounds, novolac-based epoxy compounds, resol-based epoxy compounds, poly(hydroxystyrene)-based epoxy compounds, oxetane compounds, methylol-containing melamine compounds, methylol-containing benzoguanamine compounds, methylol-containing urea compounds, methylol-containing phenol compounds, alkoxyalkyl-containing melamine compounds, alkoxyalkyl-containing benzoguanamine compounds, alkoxyalkyl-containing urea compounds, alkoxyalkyl-containing phenol compounds, carboxymethyl-containing melamine resins, carboxymethyl-containing benzoguanamine resins, carboxymethyl-containing urea resins, carboxymethyl-containing phenol resins, carboxymethyl-containing melamine compounds, carboxymethyl-containing benzoguanamine compounds, carboxymethyl-containing urea compounds, and carboxymethyl-containing phenol compounds. These can be used alone or in combination of two or more.

[0136] The content of the crosslinking agent (QN2) is, for example, 10 to 40 mol % relative to all acidic functional groups in the phenolic hydroxyl group-containing resin (QN1) from the viewpoint of efficiently rendering the phenolic hydroxyl group-containing resin (QN1) insoluble or insoluble in an alkaline developer.

[0137] Examples of the positive photosensitive resin (or positive chemically amplified resin; QP) include alkali-soluble resins into which an acid-dissociable group is introduced as a protecting group (protecting group-introduced resin; QP1).

[0138] The protecting group-introduced resin (QP1) is a resin in which a part or all of the hydrogen atoms of an acidic functional group (eg, a phenolic hydroxyl group, a carboxyl group, a sulfonyl group, etc.) in an alkali-soluble resin are substituted with an acid-dissociable group.

[0139] The protective group-introduced resin (QP1) is a resin that is insoluble or poorly soluble in alkaline developer. + X - ) and when dissociated, it becomes an alkali-soluble resin that is easily soluble in an alkali developer.

[0140] The alkali-soluble resin is, for example, a resin having an HLB value of 4 to 19 (preferably 5 to 18, particularly preferably 6 to 17).

[0141] The alkali-soluble resin includes a resin containing a phenolic hydroxyl group, a resin containing a carboxyl group, and a resin containing a sulfonic acid group.

[0142] Examples of the phenolic hydroxyl group-containing resin include the same resins as those described above for the phenolic hydroxyl group-containing resin (QN1).

[0143] The carboxyl group-containing resin is not particularly limited as long as it is a polymer having a carboxyl group, and examples thereof include homopolymers of a carboxyl group-containing vinyl monomer (Ba) and homopolymers of a carboxyl group-containing vinyl monomer (Ba) and a hydrophobic group-containing vinyl monomer (Bb).

[0144] Examples of the carboxyl group-containing vinyl monomer (Ba) include (meth)acrylic acid.

[0145] Examples of the vinyl monomer (Bb) containing a hydrophobic group include (meth)acrylic acid C 1-20 (Meth)acrylates (Bb1) such as alkyl esters and alicyclic group-containing (meth)acrylates, and aromatic hydrocarbon monomers (Bb2) such as hydrocarbon monomers having a styrene skeleton and vinylnaphthalene.

[0146] The sulfonic acid group-containing resin is not particularly limited as long as it is a polymer having a sulfonic acid group, and can be obtained, for example, by vinyl polymerization of a sulfonic acid group-containing vinyl monomer (Bc) such as vinyl sulfonic acid or styrene sulfonic acid and, if necessary, a hydrophobic group-containing vinyl monomer (Bb).

[0147] Examples of the acid-dissociable group introduced as a protective group into the resin (QP1) include 1-substituted methyl groups such as methoxymethyl, benzyl, and tert-butoxycarbonylmethyl; 1-substituted ethyl groups such as 1-methoxyethyl and 1-ethoxyethyl; 1-branched alkyl groups such as tert-butyl; silyl groups such as trimethylsilyl; germyl groups such as trimethylgermyl; alkoxycarbonyl groups such as tert-butoxycarbonyl; acyl groups; cyclic acid-dissociable groups such as tetrahydropyranyl, tetrahydrofuranyl, tetrahydrothiopyranyl, and tetrahydrothiophenyl. These groups may be contained alone or in combination of two or more.

[0148] The introduction rate of the acid-dissociable groups in the protecting group-introduced resin (QP1) [i.e., the ratio of the number of acid-dissociable groups to the total number of unprotected acidic functional groups and acid-dissociable groups in the protecting group-introduced resin (QP1)] cannot be determined in a general manner depending on the type of the acid-dissociable groups and the alkali-soluble resin into which the groups are introduced, but is preferably 10 to 100%, and more preferably 15 to 100%.

[0149] The polystyrene-equivalent weight average molecular weight (Mw) of the protecting group-introduced resin (QP1) measured by GPC is, for example, 1,000 to 150,000, or preferably 3,000 to 100,000.

[0150] The photoresist of the present invention can be prepared, for example, by dissolving the acid generator (or the sulfonium salt (1)) in an organic solvent and mixing the organic solvent with a photosensitive resin.

[0151] The photoresist of the present invention may contain one or more other components as required in addition to the above-mentioned acid generator (or the above-mentioned sulfonium salt (1)) and the photosensitive resin. Examples of the other components include organic solvents, pigments, dyes, photosensitizers, dispersants, surfactants, fillers, leveling agents, defoamers, antistatic agents, ultraviolet absorbers, pH adjusters, surface modifiers, plasticizers, drying accelerators, and the like.

[0152] As the above-mentioned organic solvent, any organic solvent that can dissolve the above-mentioned photosensitive resin and can impart good coating properties to the photoresist can be used. However, among them, from the perspective of being able to easily dry the photoresist after coating, it is preferred to use an organic solvent with a boiling point of 200°C or less. As such an organic solvent, aromatic hydrocarbons such as toluene; alcohols such as ethanol and methanol; ketones such as cyclohexanone, methyl ethyl ketone, and acetone; esters such as ethyl acetate, butyl acetate, and ethyl lactate; glycol monoether monoesters such as propylene glycol monomethyl ether acetate, etc. These can be used alone or in combination of two or more.

[0153] The photoresist of the present invention contains a sulfonium salt (1) having a high sensitivity to light with a wavelength of 20 nm or less. Therefore, when irradiated with light with a wavelength of 20 nm or less, an acid (H + X - Afterwards, due to the generated acid (H + X - ), the solubility of the photosensitive resin in the exposed part in the developer changes. In the case where the photosensitive resin is a negative photosensitive resin, the solubility decreases due to irradiation. On the other hand, in the case where the photosensitive resin is a positive photosensitive resin, the solubility increases due to irradiation. Therefore, if the photoresist of the present invention is used, an etching mask can be formed with excellent precision by photolithography.

[0154] [Method for manufacturing electronic device]

[0155] The method for manufacturing an electronic device of the present invention includes a step of performing patterning by photolithography using the above-mentioned photoresist.

[0156] The step of performing patterning by photolithography using the above-mentioned photoresist is preferably a step of forming an etching mask on the substrate through the following steps 1 to 3.

[0157] Step 1: forming a coating film of the photoresist on a substrate;

[0158] Step 2: a step of irradiating the coating film with light in a pattern shape;

[0159] Step 3: a step of performing alkali development.

[0160] (Process 1)

[0161] This step is a step of forming a coating film of the photoresist on the substrate to be etched. The coating film of the photoresist can be formed by applying the photoresist to the substrate using a known method such as spin coating, shower coating, roll coating, spray coating, screen printing, etc., and then drying it.

[0162] (Process 2)

[0163] This step is a step of irradiating the coating film obtained in step 1 with light in a patterned shape by a method such as irradiating light through a photomask having a pattern. The light used for the light irradiation is not particularly limited as long as it can decompose the sulfonium salt (1) to generate a strong acid, and of course, light with a longer wavelength can be suitably used, and light with a wavelength of 20 nm or less, such as EUV (extreme ultraviolet), EB (electron beam), and X-ray, can also be suitably used.

[0164] From the viewpoint of increasing the difference in solubility in an alkaline developer between an exposed portion and an unexposed portion, heating is preferably performed at a temperature of 60 to 200° C. for about 0.1 to 120 minutes after light irradiation.

[0165] (Process 3)

[0166] This step is a step of subjecting the photoresist coating film obtained in step 2 to an alkali development treatment.

[0167] Examples of the alkali developer used in the alkali development treatment include an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, sodium hydrogen carbonate, and an aqueous tetramethylammonium salt solution.

[0168] Methanol, ethanol, isopropyl alcohol, tetrahydrofuran, N-methylpyrrolidone, or the like may be added to the above-mentioned alkaline developer.

[0169] The alkali development treatment can be performed by applying the alkali developer to the coating film by a method such as dipping, showering, or spraying.

[0170] The temperature of the alkali developer is, for example, 25 to 40° C. The alkali development time can be appropriately determined according to the thickness of the resist, but is, for example, about 1 to 5 minutes.

[0171] An etching mask can be formed on the substrate through step 3. When the substrate is etched using the etching mask obtained in this way, a high-precision electronic device can be manufactured.

[0172] The electronic devices mentioned above include, for example, display devices such as organic EL displays and liquid crystal displays; input devices such as touch panels; light-emitting devices; sensor devices; MEMS (Micro Electro Mechanical Systems) devices such as optical scanners, optical switches, acceleration sensors, pressure sensors, gyroscopes, micro flow channels, and inkjet heads.

[0173] The above-mentioned various structures and their combinations of the present invention are examples, and the addition, omission, substitution and change of the structures can be appropriately performed without departing from the scope of the present invention. In addition, the present invention is not limited to the embodiments, but only limited by the description of the scope of the technical solution claimed for protection.

[0174] Example

[0175] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[0176] Production Example 1

[0177] To a tetrahydrofuran solution of 3,5-difluorophenylmagnesium bromide prepared by a conventional method using 96.5 g of 1-bromo-3,5-difluorobenzene, 13.4 g of magnesium, and 400 g of tetrahydrofuran, a solution prepared by diluting 28.6 g of thionyl chloride with 50 g of tetrahydrofuran was added dropwise at a temperature in the system not higher than -5°C. After completion of the dropwise addition, the reaction was continued at room temperature for 1 hour to complete the reaction.

[0178] The solution was added to 500 g of ion exchange water so that the temperature in the system was not higher than 15°C, and stirred for 1 hour. Thereafter, 300 g of ethyl acetate was added and stirred for 1 hour. After removing the water layer, the mixture was washed three times with 300 g of ion exchange water. The organic layer was desolvated, and the obtained brown residue was recrystallized with cyclohexane to obtain 26.0 g of bis(3,5-difluorophenyl)sulfoxide.

[0179] Production Example 2

[0180] 43.6 g of bis(3,5-bis(trifluoromethyl)phenyl)sulfoxide was obtained by the same method as in Production Example 1 except that 96.5 g of 1-bromo-3,5-difluorobenzene was changed to 146.5 g of 1-bromo-3,5-bis(trifluoromethyl)benzene.

[0181] Production Example 3

[0182] 6.86 g of bis(3,5-difluorophenyl)sulfoxide synthesized in Production Example 1 was dissolved in 30 g of benzene, and 8.46 g of trifluoromethanesulfonic anhydride was added dropwise in a range where the temperature in the system was not higher than -5°C.

[0183] After the addition is completed, the reaction is continued at room temperature for 1 hour to complete the reaction. The supernatant is removed, and 50 g of ion exchange water is added to the oily precipitate at a temperature not higher than 15°C, followed by 75 g of tetrahydrofuran and 30 g of toluene, and stirred for 1 hour. The upper layer is removed, and the remaining solution is washed twice with 30 g of toluene. Thereafter, the solution is neutralized with sodium bicarbonate, 100 g of dichloromethane is added for extraction, the water layer is removed, and then the organic layer is washed three times with 50 g of ion exchange water. The organic layer is desolvated, and when crystals are precipitated, 150 g of methyl-tert-butyl ether is added to precipitate white crystals. The crystals are separated and collected by filtration, and dried under reduced pressure to obtain 6.53 g of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate.

[0184] Production Example 4

[0185] 1.37 g of [bis(3,5-di(trifluoromethyl)phenyl)]phenylsulfonium trifluoromethanesulfonate was obtained in the same manner as in Preparation Example 3 except that 6.86 g of bis(3,5-difluorophenyl)sulfoxide was replaced with 11.9 g of bis(3,5-di(trifluoromethyl)phenyl)sulfoxide synthesized in Preparation Example 2.

[0186] Production Example 5

[0187] 7.67 g of [bis(3,5-difluorophenyl)](2,5-dimethylphenyl)sulfonium trifluoromethanesulfonate was obtained in the same manner as in Production Example 3 except that 30.0 g of p-xylene was used instead of 30.0 g of benzene.

[0188] Production Example 6

[0189] 6.86 g of bis(3,5-difluorophenyl)sulfoxide and 5.40 g of anisole synthesized in Preparation Example 1 were dissolved in 20 g of dichloromethane, and 8.46 g of trifluoromethanesulfonic anhydride was added dropwise in a range of not more than -5°C in the system. After the addition was completed, the reaction was continued at room temperature for 1 hour to complete the reaction. 150 g of methyl-tert-butyl ether was added to the reaction solution to precipitate brown crystals. The crystals were separated and collected by filtration, dissolved in 30 g of dichloromethane, and 100 g of a 17% dichloromethane solution of boron tribromide was added dropwise in a range of not more than 10°C in the system. After the addition was completed, the reaction was continued at room temperature for 1 hour to complete the reaction. 50 g of ion exchange water was added to the reaction solution, and after neutralization with sodium bicarbonate, the water layer was removed, and then the organic layer was washed 3 times with 50 g of ion exchange water. The organic layer was desolvated, and when crystals precipitated, 150 g of methyl-tert-butyl ether was added to precipitate white crystals. The crystals were separated and collected by filtration and dried under reduced pressure to obtain 5.58 g of [bis(3,5-difluorophenyl)](4-hydroxyphenyl)sulfonium trifluoromethanesulfonate.

[0190] Production Example 7

[0191] 1.1 g of magnesium and 23.3 g of tetrahydrofuran were added to a degassed and nitrogen-substituted reaction vessel, and 8.8 g of 1-bromo-3,5-difluorobenzene was added dropwise so that the temperature in the system did not exceed 60° C. After the addition, the reaction was continued at 40 to 60° C. for 1 hour to obtain a tetrahydrofuran solution of 3,5-difluorophenylmagnesium bromide.

[0192] In another reaction vessel that was degassed and replaced with nitrogen, 5.0 g of bis(3,5-difluorophenyl)sulfoxide synthesized in Preparation Example 1, 30.0 g of tetrahydrofuran, and 27.3 g of trimethylsilyl trifluoromethanesulfonate were added, and the mixture was cooled to 5° C. in an ice bath. Then, a tetrahydrofuran solution of 3,5-difluorophenylmagnesium bromide synthesized previously was added dropwise from a dropping funnel so that the temperature in the system did not exceed 15° C. After the addition was completed, the reaction was continued at 10° C. for 1 hour to complete the reaction.

[0193] The solution was added to 80.0 g of ion exchange water cooled to 5 ° C by ice bath at a temperature not higher than 15 ° C. After the addition, it was stirred for 1 hour at a temperature not higher than 25 ° C. Thereafter, 60.0 g of toluene was added and stirred for 1 hour. The toluene layer was removed, and the remaining solution was washed twice with 50.0 g of toluene. Thereafter, 30.0 g of dichloromethane was added and extracted, the water layer was separated, and then the organic layer was washed 4 times with 7.5 g of ion exchange water. The organic layer was desolvated, and 6.0 g of methanol was added to the obtained yellow oily residue and dissolved. The solution was slowly added to 25.0 g of methyl-tert-butyl ether under stirring to precipitate crystals. The crystals were separated and collected by filtration and dried under reduced pressure to obtain 4.0 g of [tris (3,5-difluorophenyl)] sulfonium trifluoromethanesulfonate.

[0194] Example 1

[0195] 6.53 g of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate synthesized in Preparation Example 3 was dissolved in 27.9 g of dichloromethane, 50.6 g of trifluoromethanesulfonic acid was added, and then 3.34 g of N-iodosuccinimide was added dropwise in a range where the temperature in the system was not higher than 5° C. After the addition was completed, the reaction was continued at room temperature for 1 hour to complete the reaction.

[0196] 36.4 g of ion exchange water was added so that the temperature in the system did not exceed 15° C., and the mixture was stirred for 30 minutes.

[0197] Thereafter, the upper layer was removed, and the remaining solution was washed twice with 36.4 g of a 5% sodium thiosulfate aqueous solution, and then washed three times with 36.4 g of ion-exchanged water.

[0198] The solvent was removed from the organic layer to obtain crude crystals, which were purified by silica gel column chromatography to obtain 5.35 g of sulfonium salts [acid generator (1)] which were salts of cations and anions listed in the following table.

[0199] Example 2

[0200] 6.86 g of bis(3,5-difluorophenyl)sulfoxide synthesized in Production Example 1 was dissolved in 78.3 g of iodobenzene, and 8.46 g of trifluoromethanesulfonic anhydride was added dropwise in a range where the temperature in the system was not higher than -5°C.

[0201] After the addition is completed, the reaction is continued at room temperature for 1 hour to complete the reaction. The supernatant is removed, and 50 g of ion exchange water is added to the oily precipitate at a temperature not higher than 15°C, followed by 75 g of tetrahydrofuran and 30 g of toluene, and the mixture is stirred for 1 hour. The upper layer is removed, and the remaining solution is washed twice with 30 g of toluene. Thereafter, the solution is neutralized with sodium bicarbonate, 100 g of dichloromethane is added for extraction, the water layer is removed, and the organic layer is washed three times with 50 g of ion exchange water. The organic layer is desolvated, and when crystals are precipitated, 150 g of methyl-tert-butyl ether is added to precipitate white crystals. The crystals are separated and collected by filtration, and dried under reduced pressure to obtain 8.23 ​​g of sulfonium salt [acid generator (2)] as a salt of a cation and an anion as described in the following table.

[0202] Example 3

[0203] 6.53 g of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate synthesized in Preparation Example 3 was dissolved in 27.9 g of dichloromethane, 50.6 g of trifluoromethanesulfonic acid was added, and then 10.01 g of N-iodosuccinimide was added dropwise at a temperature of not more than 5°C.

[0204] After the addition was completed, the reaction was continued at room temperature for 10 hours to complete the reaction. 36.4 g of ion exchange water was added so that the temperature in the system was not higher than 15°C and stirred for 30 minutes. The upper layer was removed, and the remaining solution was washed twice with 36.4 g of 5% sodium thiosulfate aqueous solution, and then washed three times with 36.4 g of ion exchange water. The organic layer was desolvated to obtain crude crystals, which were purified by silica gel column chromatography to obtain 7.55 g of sulfonium salt [acid generator (3)] as a salt of a cation and anion described in the following table.

[0205] Example 4

[0206] 6.53 g of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate synthesized in Preparation Example 3 was dissolved in 27.9 g of dichloromethane, 50.6 g of trifluoromethanesulfonic acid was added, and then 13.35 g of N-iodosuccinimide was added dropwise at a temperature of not more than 5°C.

[0207] After the addition was completed, the reaction was continued at room temperature for 20 hours to complete the reaction. 36.4 g of ion exchange water was added so that the temperature in the system was not higher than 15° C. and stirred for 30 minutes. The upper layer was removed, and the remaining solution was washed twice with 36.4 g of 5% sodium thiosulfate aqueous solution, and then washed three times with 36.4 g of ion exchange water. The organic layer was desolvated to obtain crude crystals, which were purified by silica gel column chromatography to obtain 8.66 g of sulfonium salt [acid generator (4)] as a salt of a cation and anion described in the following table.

[0208] Example 5

[0209] 7.10 g of sulfonium salts [acid generator (5)] which are salts of cations and anions shown in the following table were obtained in the same manner as in Example 1 except that 9.22 g of [bis(3,5-di(trifluoromethyl)phenyl)]phenylsulfonium trifluoromethanesulfonate synthesized in Production Example 4 was used instead of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate.

[0210] Example 6

[0211] 5.59 g of sulfonium salts [acid generator (6)] which are salts of cations and anions shown in the following table were obtained in the same manner as in Example 1 except that 6.91 g of [bis(3,5-difluorophenyl)](2,5-dimethylphenyl)sulfonium trifluoromethanesulfonate synthesized in Production Example 5 was used instead of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate.

[0212] Example 7

[0213] 5.49 g of sulfonium salts [acid generator (7)] which are salts of cations and anions shown in the following table were obtained in the same manner as in Example 1 except that 6.75 g of [bis(3,5-difluorophenyl)](4-hydroxyphenyl)sulfonium trifluoromethanesulfonate synthesized in Production Example 6 was used instead of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate.

[0214] Example 8

[0215] 5.66 g of sulfonium salts [acid generator (8)] which are salts of cations and anions shown in the following table were obtained in the same manner as in Example 1 except that 7.02 g of [tris(3,5-difluorophenyl)]sulfonium trifluoromethanesulfonate synthesized in Preparation Example 7 was used instead of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate.

[0216] Example 9

[0217] 7.02 g of [tris(3,5-difluorophenyl)]sulfonium trifluoromethanesulfonate synthesized in Preparation Example 7 was dissolved in 27.9 g of dichloromethane, 50.6 g of trifluoromethanesulfonic acid was added, and then 6.67 g of N-iodosuccinimide was added dropwise at a temperature of not more than 5°C.

[0218] After the addition was completed, the reaction was continued at room temperature for 10 hours to complete the reaction. 36.4 g of ion exchange water was added so that the temperature in the system did not exceed 15° C. and stirred for 30 minutes. The upper layer was removed, and the remaining solution was washed twice with 36.4 g of a 5% sodium thiosulfate aqueous solution and then washed three times with 36.4 g of ion exchange water. The organic layer was desolvated to obtain crude crystals, which were purified by silica gel column chromatography to obtain 6.77 g of sulfonium salt [acid generator (9)] as a salt of a cation and anion described in the following table.

[0219] Example 10

[0220] 7.87 g of sulfonium salts [acid generator (10)] which are salts of cations and anions shown in the following table were obtained in the same manner as in Example 3 except that 7.02 g of [tris(3,5-difluorophenyl)]sulfonium trifluoromethanesulfonate synthesized in Preparation Example 7 was used instead of [bis(3,5-difluorophenyl)]phenylsulfonium trifluoromethanesulfonate.

[0221] Embodiment 11

[0222] 7.87 g of the sulfonium salt represented by (1-10) synthesized in Example 10 was dissolved in 25.4 g of dichloromethane, added to 65.2 g of a 5% aqueous potassium nonafluorobutanesulfonate solution, and stirred at 25° C. for 2 hours. After removing the aqueous layer, the organic layer was washed several times with 23.7 g of ion-exchanged water and dried under reduced pressure to obtain 8.27 g of a sulfonium salt [acid generator (11)] which is a salt of a cation and an anion described in the following table.

[0223] Example 12

[0224] 10.48 g of sulfonium salts (acid generator (12)) which are salts of cations and anions shown in the following table were obtained in the same manner as in Example 11 except that 56.6 g of 10% lithium bis(nonafluorobutanesulfonyl)imide aqueous solution was used instead of 5% potassium nonafluorobutanesulfonate aqueous solution.

[0225] (evaluate)

[0226] The acid generators obtained in the examples and the acid generators described in the comparative examples in Table 3 below were evaluated for solvent solubility and photosensitivity by the following methods. The results are shown in the following table.

[0227] <Solvent solubility>

[0228] 0.1 g of an acid generator was added to a test tube, and 0.2 g of propylene glycol monomethyl ether acetate was added at a time at 25°C until the acid generator was completely dissolved. The concentration of the acid generator when completely dissolved was determined, and the solvent solubility was evaluated according to the following criteria.

[0229] Evaluation Benchmarks

[0230] Good (◎): The concentration of the acid generator is 5% by weight or more;

[0231] Pass (○): The acid generator concentration is 2% by weight or more and less than 5% by weight;

[0232] Unqualified (×): The acid generator concentration is less than 2% by weight.

[0233] <Light sensitivity>

[0234] The acid generator was diluted with acetonitrile to a molar concentration of 2.5 mM, and rhodamine B base (acid color developing reagent, manufactured by Sigma-Aldrich) was added to a molar concentration of 2.5 mM to prepare a sample solution.

[0235] The obtained sample solution was placed in a quartz cell with an optical path length of 1 cm and an exposure device (JEOL JBX-9300, manufactured by JEOL Ltd.) was used at an accelerating voltage of 100 kV and a cumulative light intensity of 50 μC / cm 2 Electron beam exposure is carried out under the conditions of.

[0236] When the acid generator in the sample solution decomposes and generates acid due to exposure, the generated acid reacts with the rhodamine B base to increase the absorbance at 556 nm. Therefore, the amount of acid generated can be determined by measuring the absorbance at 556 nm after exposure.

[0237] The absorbance was measured using a spectrophotometer (UV-vis).

[0238] The acid concentration in the sample solution after exposure was quantified based on the absorbance of the sample solution after exposure at 556 nm using a calibration curve (standard substance: p-toluenesulfonic acid).

[0239] The acid generation rate was calculated based on the following formula, and the photosensitivity was evaluated based on the following criteria based on the calculated acid generation rate.

[0240] Acid generation rate (%) = acid concentration after exposure (mM) / acid generator concentration before exposure (mM) × 100

[0241] (Evaluation criteria)

[0242] Excellent (◎): Acid generation rate is more than 50%;

[0243] Good (○): Acid generation rate is 40% or more and less than 50%;

[0244] Pass (△): Acid generation rate is more than 20% and less than 40%;

[0245] Unqualified (×): Acid generation rate is less than 20%.

[0246] [Table 1]

[0247]

[0248] [Table 2]

[0249]

[0250] [Table 3]

[0251]

[0252] Tables 1 to 3 show that when the acid generator (or sulfonium salt (1)) of the present invention contains iodine atoms, the solvent solubility is significantly improved compared to the case where no iodine atoms are contained, and the photosensitivity to electron beams is improved.

[0253] It is found that the acid generator (or sulfonium salt (1)) of the present invention can be suitably used as an acid generator for photoresists (particularly an acid generator for photoresists used in photolithography using light with a wavelength of 20 nm or less) because it has excellent solvent solubility and photosensitivity as described above. When photolithography (particularly photolithography using light with a wavelength of 20 nm or less) is performed using a photoresist containing the acid generator (or sulfonium salt (1)) of the present invention, a fine pattern can be formed with high precision, and electronic devices can be increased in capacity and reduced in size.

[0254] Industrial Applicability

[0255] The sulfonium salt (1) of the present invention has excellent sensitivity to light with a wavelength of 20 nm or less, and can be easily decomposed by irradiation with light of the above wavelength to generate acid (H + X - ). Therefore, when photolithography using light having a wavelength of 20 nm or less is performed using a photoresist containing the sulfonium salt (1), a fine pattern can be formed with high precision, and further capacity and size of electronic devices can be further increased.

Claims

1. A sulfonium salt represented by the following formula (1): In the formula, Rf 1 , Rf 2 , Rf 11 and Rf 12 are the same or different, representing a fluorine atom or a fluoroalkyl group; R 1 , R 2 , R 3 , R 11 , R 12 , R 13 , R 21 , R 23 and R 25 are the same or different, representing a hydrogen atom, a hydroxyl group, an alkyl group or an iodine atom; R 22 , R 24 are the same or different and represent a hydrogen atom, a hydroxyl group, an alkyl group, an iodine atom, a fluorine atom or a fluoroalkyl group; X - represents a univalent counter anion; wherein, Selected from R 1 , R 2 , R 3 , R 11 , R 12 , R 13 and R 21 ~R 25 At least one of them represents an iodine atom.

2. The sulfonium salt according to claim 1, wherein The monovalent counter anion is a sulfonate anion or a nitrogen anion.

3. An acid generator comprising the sulfonium salt according to claim 1 or 2. 4 . A photoresist comprising the acid generator according to claim 3 and an acid-reactive compound. 5 . A method for manufacturing an electronic device, comprising a step of performing patterning by photolithography using the photoresist according to claim 4 .

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