Sulfonium salt and acid generator containing the sulfonium salt

Abstract

To provide a novel sulfonium salt which has superior solvent solubility and sensitivity to ultra-short wavelength light, and which exhibits acid generation by rapid decomposition upon ultra-short wavelength light irradiation.SOLUTION: The present invention provides a sulfonium salt represented by formula (1), wherein Rf1, Rf2, Rf11, and Rf12 represent F or a fluoroalkyl group; Ra represents a hydroxy group or the like; m and n represent integers of 1 or more, provided that m+n is an integer of 5 or less; and X- represents a monovalent counter anion.SELECTED DRAWING: None

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 manufacturing an electronic device or an optical device using the photoresist.

Background Art

[0002] The increase in capacity and miniaturization of electronic devices and optical devices are achieved by increasing the density and integration of semiconductor integrated circuits. And, as a method for increasing the density and integration of semiconductor integrated circuits, there is a method of forming a fine pattern on a semiconductor by making full use of photolithography technology.

[0003] In photolithography technology, pattern formation is performed by performing an exposure process and a development process on a coating film of a chemically amplified photoresist containing a photoacid generator and an acid-reactive compound (this may be referred to as a "resist film" in some cases). And, by shortening the wavelength of the light beam used in the exposure process, the pattern can be miniaturized.

[0004] As a photoacid generator, triphenylsulfonium salt is known (see Patent Document 1). And, a photoresist containing triphenylsulfonium salt can process a pattern with high accuracy by performing an exposure process using a KrF excimer laser or an ArF excimer laser. However, the said photoresist has low sensitivity to light beams with ultra-short wavelengths such as EUV (extreme ultraviolet ray), EB (electron beam), and X-ray, and it has been difficult to use for photolithography using EUV or the like.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Then, the inventors of the present invention found that when a triarylsulfonium cation contains a fluorine atom or a fluoroalkyl group and an iodine atom, the sensitivity to ultra-short wavelength light is improved, and by irradiating with ultra-short wavelength light, it easily decomposes to generate an acid (H + X - ), but it was found that the solvent solubility decreases.

[0007] In addition, in a photoresist, an acid generator generally coexists with a quencher added to improve pattern resolution. However, a salt of a triarylsulfonium cation having an iodine atom and having a fluorine atom or a fluoroalkyl group at a position para to the position where the sulfur atom is bonded, such as [bis(p-fluorophenyl)](p-iodophenyl)sulfonium cation, and a counter anion, it was found that it rapidly decomposes in the presence of a quencher and the photosensitivity decreases or the photosensitivity is lost.

[0008] Therefore, an object of the present invention is to provide a novel sulfonium salt having excellent solvent solubility, sensitivity to ultra-short wavelength light, and the property of rapidly decomposing upon irradiation with ultra-short wavelength light to generate an acid. Another object of the present invention is to provide a novel sulfonium salt having excellent solvent solubility, sensitivity to ultra-short wavelength light, and quencher resistance. Another object of the present invention is to provide a novel acid generator having excellent solvent solubility, sensitivity to ultra-short wavelength light, and the property of rapidly decomposing upon irradiation with ultra-short wavelength light to generate an acid. Another object of the present invention is to provide a novel acid generator having excellent solvent solubility, sensitivity to ultra-short wavelength light, and quencher resistance. Another object of the present invention is to provide a photoresist that can be used in photolithography using ultra-short wavelength light. Another object of the present invention is to provide a method for manufacturing an electronic device or an optical device using the photoresist.

Means for Solving the Problems

[0009] As a result of intensive studies to solve the above problems, the present inventors have found that by incorporating a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group, which has an action of improving solvent solubility, together with a fluorine atom or a fluoroalkyl group and an iodine atom, into a triarylsulfonium cation, a decrease in solvent solubility can be suppressed. When a sulfonium salt having the cation is incorporated into a photoresist in a state of being dissolved in a solvent, it becomes uniformly dispersed in the photoresist, and when an exposure treatment and a development treatment are performed, a pattern with good accuracy can be obtained. And the sulfonium salt represented by the following formula (1) has excellent solvent solubility, sensitivity to light of an ultra-short wavelength, and quencher resistance in which decomposition is suppressed even in the coexistence of a quencher. It has been found that a photoresist containing the sulfonium salt represented by the following formula (1) and a quencher is excellent in storage stability and can maintain excellent pattern accuracy not only immediately after preparation but also after a lapse of time from preparation. The present invention has been completed based on these findings.

[0010] That is, the present invention provides a sulfonium salt represented by the following formula (1).

Chemical Formula

[0011] The present invention also provides the sulfonium salt wherein the monovalent counter anion is a sulfonate anion or a sulfonylimide anion.

[0012] The present invention also provides an acid generator containing the sulfonium salt.

[0013] The present invention also provides a photoresist containing the acid generator and an acid-reactive compound.

[0014] The present invention also provides a method for manufacturing an electronic device or an optical device, including a step of forming a pattern by photolithography using the photoresist.

Advantages of the Invention

[0015] The sulfonium salt represented by the above formula (1) (hereinafter sometimes referred to as "sulfonium salt (1)") has excellent sensitivity to light rays of ultra-short wavelengths, and by irradiating with light of said wavelength, it can be easily decomposed to generate an acid (H + X - :X - derived from the monovalent counter anion contained in the sulfonium salt (1)).

[0016] Also, the sulfonium salt (1) has excellent solvent solubility. Therefore, when the sulfonium salt (1) is dissolved in a solvent and blended into a photoresist, it becomes uniformly dispersed in the photoresist, and when an exposure process and a development process using light rays of ultra-short wavelengths are performed, a fine pattern can be formed with high precision.

[0017] Furthermore, general acid generators are easily decomposed and lose photosensitivity or have reduced photosensitivity in the presence of a quencher. However, sulfonium salt (1) has quencher resistance, and its decomposition is suppressed even in the presence of a quencher, allowing it to maintain high photosensitivity. When a quencher is added to a photoresist containing sulfonium salt (1), a resist film with improved pattern resolution can be obtained.

[0018] Moreover, a photoresist containing sulfonium salt (1) and a quencher has excellent storage stability, so it can be prepared in advance and used at any timing.

[0019] If the obtained resist film is used as an etching mask, it becomes possible to achieve further increases in the capacity and further miniaturization of electronic devices and optical devices.

BEST MODE FOR CARRYING OUT THE INVENTION

[0020] [Sulfonium Salt] The sulfonium salt (1) of the present invention is a compound represented by the following formula (1).

CHEMICAL FORMULA

[0021] Further, the symbols A, B, and C attached to the benzene ring in the above formula are symbols attached to distinguish the three benzene rings in the formula. Hereinafter, the benzene ring to which A is attached will be referred to as "benzene ring A", the benzene ring to which B is attached will be referred to as "benzene ring B", and the benzene ring to which C is attached will be referred to as "benzene ring C".

[0022] The hydroxyalkyl group is a group represented by the general formula [-R-OH], and R represents a group obtained by removing one hydrogen atom from the structural formula of an alkyl group.

[0023] The alkoxy group is a group represented by the general formula [-OR], and R represents an alkyl group.

[0024] The fluoroalkyl group is a group in which at least one of the hydrogen atoms of the alkyl group is substituted with a fluorine atom.

[0025] The alkyl group is, for example, C 1-5 alkyl group (that is, an alkyl group having 1 to 5 carbon atoms), and examples thereof include linear or branched alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, and pentyl group.

[0026] As the hydroxyalkyl group, hydroxy C 1-5 alkyl group is preferable, hydroxy C 1-3 alkyl group is more preferable, and hydroxy C 1-2 alkyl group is particularly preferable.

[0027] As the alkoxy group, C 1-5 alkoxy group is preferable, C 1-3 alkoxy group is more preferable, and C 1-2 alkoxy group is particularly preferable.

[0028] As the fluoroalkyl group, from the viewpoint of easy availability of raw materials, fluoro C 1-5 alkyl group is preferable, fluoro C 1-3 alkyl group is more preferable, and fluoro C 1-2An alkyl group is particularly preferred.

[0029] As the fluoroalkyl group, a group in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms, that is, a perfluoroalkyl group (for example, perfluoro C 1-5 alkyl group) is preferred.

[0030] Said m is the number of iodine atoms bonded to benzene ring C, and represents an integer of 1 or more (for example, an integer of 1 to 4). Among them, from the viewpoint of improving the sensitivity to extreme ultraviolet light, an integer of 1 to 3 is preferable, and from the viewpoint of improving the sensitivity to extreme ultraviolet light while suppressing a decrease in solvent solubility, 1 or 2 is particularly preferable, and 2 is especially preferable.

[0031] In benzene ring C, as the position where the iodine atom is bonded, it is preferable to change according to the number of iodine atoms to be bonded. For example, when m = 1, it may be any of the ortho position, meta position, or para position with respect to the position where the sulfur atom shown in formula (1) is bonded. When m = 2, it is preferably bonded to the meta position with respect to the position where the sulfur atom shown in formula (1) is bonded. When m = 3, it is preferably bonded to the ortho position and para position with respect to the position where the sulfur atom shown in formula (1) is bonded.

[0032] Said n is the number of R a groups bonded to benzene ring C, and represents an integer of 1 or more (for example, an integer of 1 to 4). Among them, from the viewpoint of suppressing a decrease in solvent solubility, an integer of 1 to 3 is preferable, and from the viewpoint of suppressing a decrease in solvent solubility while improving the sensitivity to extreme ultraviolet light, 1 or 2 is particularly preferable, and 1 is especially preferable.

[0033] When n is an integer of 2 or more, two or more R a may be the same or different.

[0034] The m + n is an integer of 5 or less (more specifically, an integer of 2 or more and 5 or less), and from the viewpoint of improving the sensitivity to light rays of an ultra-short wavelength while suppressing a decrease in solvent solubility, it is preferably an integer of 2 to 4, and particularly preferably 2 or 3.

[0035] In the benzene ring A and benzene ring B in the above formula (1), other substituents may be bonded in addition to the above groups. Examples of other substituents include an alkyl group, an iodine atom, and the like.

[0036] In the benzene ring C in the above formula (1), other substituents may be bonded in addition to the above groups. Examples of other substituents include an alkyl group and the like.

[0037] In the above formula, X - represents a monovalent counter anion, and examples thereof include a halogen ion, a halogen oxo acid anion, a boron anion, a phosphate anion, a sulfate anion, a sulfonate anion, a sulfonyl imide anion, a carboxylic acid anion, a methide anion, an antimony anion, OH - , SCN - , NO 2 - , NO 3 - and the like.

[0038] Examples of the halogen ion include Cl - , Br - , I - and the like.

[0039] Examples of the halogen oxo acid anion include ClO 4 - , IO 3 - , BrO 3 - and the like.

[0040] Examples of the boron anion include inorganic boron anions such as BF 4 - and the like, and (C 6 F 5 )4 B - and ((CF 3 )) 2 C 6 H 3 ) 4 B - and organic boron anions such as tetraphenylborate, tetrakis(monofluorophenyl)borate, tetrakis(difluorophenyl)borate, tetrakis(trifluorophenyl)borate and the like.

[0041] Examples of the phosphate anion include inorganic phosphate anions such as PF 6 - , PO 4 3- and organic phosphate anions such as (CF 3 CF 2 ) 5 PF - , (CF 3 CF 2 ) 4 PF 2 - , (CF 3 CF 2 ) 3 PF 3 - , (CF 3 CF 2 ) 2 PF 4 - , (CF 3 CF 2 )PF 5 - and the like.

[0042] The sulfonate anion is represented by, for example, the following formula (s1). R s1 -SO 3 - (s1) (In the formula, R s1 represents an organic group)

[0043] Examples of the organic group in R s1 include a hydrocarbon group which may have a substituent, a heterocyclic group which may have a substituent, and two or more of the above groups being a single bond or -O-, -CO2 -, -S-, -SO 3 -, and -SO 2 N(R s2 )-linked groups are included. The above R s2 represents a hydrogen atom or an alkyl group (e.g., C 1-30 alkyl group). Examples of the substituent include halogen atoms such as a fluorine atom.

[0044] The hydrocarbon group includes a saturated hydrocarbon group and an unsaturated hydrocarbon group.

[0045] The hydrocarbon group is, for example, a C 1-30 hydrocarbon group. The C 1-30 hydrocarbon group includes, for example, a C 1-30 aliphatic hydrocarbon group, a C 3-30 alicyclic hydrocarbon group, a C 6-30 aromatic hydrocarbon group, and a group formed by bonding two or more of these.

[0046] The C 1-30 hydrocarbon group is preferably a C 1-30 alkyl group, a C 2-30 alkenyl group, a C 6-15 aryl group, a C 6-15 cycloalkyl group, a C 6-15 bridged cyclic hydrocarbon group, and a group formed by bonding two or more of these.

[0047] The heterocyclic group is a group obtained by removing one hydrogen atom from the structural formula of the heterocycle. The heterocycle includes an aromatic heterocycle and a non-aromatic heterocycle. Examples of such a heterocycle include a 3- to 10-membered ring (preferably a 4- to 6-membered ring) having a carbon atom and at least one heteroatom (e.g., an oxygen atom, a sulfur atom, a nitrogen atom, etc.) in the atoms constituting the ring, and a condensed ring thereof.

[0048] Specific examples of the sulfonate anion include CH 3 SO 3 - , C 4 H 9 SO 3- , CF 3 SO 3 - , C 2 F 5 C 4 H 4 SO 3 - , C 4 F 9 SO 3 - , examples include benzenesulfonate anion, p - toluenesulfonate anion, camphorsulfonate anion, etc.

[0049] The sulfonylimide anion is represented by, for example, the following formula (n1). (R n1 SO 2 ) 2 N - (n1) (In the formula, two Rs n1 are the same or different and represent organic groups)

[0050] Examples of the organic group in R n1 are the same as those in R s1 .

[0051] Specific examples of the sulfonylimide anion include (FSO 2 ) 2 N - , (CF 3 SO 2 ) 2 N - , (C 4 F 9 SO 2 ) 2 N - , (C 2 F 5 SO 2 ) 2 N - , etc.

[0052] The carboxylic acid anion is represented by, for example, the following formula (c1). R c1 -COO - (c1) (wherein, R c1 represents an organic group)

[0053] Examples of the organic group in R c1 are the same as those of the organic group in R s1 .

[0054] Specific examples of the carboxylic acid anion include, for example, CF 3 CO 2 - , CH 3 CO 2 - , C 2 H 5 CO 2 - , C 6 H 5 CO 2 - and the like.

[0055] Examples of the methide anion include, for example, the sulfonylmethide anion represented by the following formula (m1). (R m1 SO 2 ) 3 C - (m1) (wherein, the three Rs m1 are the same or different and represent an organic group)

[0056] Examples of the organic group in R m1 are the same as those of the organic group in R s1 .

[0057] Specific examples of the methide anion include (CF 3 SO 2 ) 3 C - and the like.

[0058] Examples of the antimony anion include, for example, SbF 6 - and the like.

[0059] In addition to the above, the monovalent counter anions include the anions described in JP-A Nos. 2013-47211, 2021-81708, 2013-80245, 2013-80240, and 2013-33161.

[0060] As the monovalent counter anion, a sulfonic acid anion or a sulfonylimide anion is preferable in terms of excellent solvent solubility and fine pattern formability.

[0061] Among the sulfonium salts (1), examples where all of Rf 1 , Rf 2 , Rf 11 , and Rf 12 are fluorine atoms are shown below. In the following formula, X - , R a are the same as above. Among the sulfonium salts (1), examples where all of Rf 1 , Rf 2 , Rf 11 , and Rf 12 are fluoroalkyl groups, or examples where they are a combination of a fluorine atom and a fluoroalkyl group include compounds corresponding to the compounds represented by the following formula.

Chemical formula

[0062]

Chemical formula

[0063]

Chemical formula

[0064]

Chemical formula

[0065] The chemical structure of the sulfonium salt (1) is, for example, 1 H-, 11 B-,13 C−, 19 F−, or 31 It can be identified by, for example, P-nuclear magnetic resonance spectrum, infrared absorption spectrum, or elemental analysis.

[0066] The sulfonium salt (1) is excellent in solubility in organic solvents.

[0067] 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; esters such as ethyl acetate, butyl acetate, 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 (PGMEA), 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 can be used alone or in combination of two or more.

[0068] Among them, the organic solvent preferably contains at least one selected from ketones, chain esters, and glycol monoether monoesters.

[0069] The solubility of the sulfonium salt (1) in an organic solvent (e.g., PGMEA) at room temperature (e.g., 25°C) and normal pressure 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. Therefore, if the sulfonium salt (1) is added to the photoresist together with the solvent, the sulfonium salt (1) can be uniformly dispersed in the photoresist.

[0070] The sulfonium salt (1) has high photosensitivity to light rays of ultra-short wavelengths such as EUV (extreme ultraviolet rays), EB (electron beams), and X-rays. And without using a photosensitizer, just by irradiating the light rays of the above wavelength, the light energy directly propagates to the sulfonium salt (1) and the photolysis proceeds rapidly, generating an acid (H + X - ).

[0071] Also, the sulfonium salt (1) is excellent in stability (or quencher resistance or base resistance), and decomposition is suppressed even in the coexistence of a quencher when the above light rays are not irradiated. The residual ratio of the sulfonium salt (1) determined by the method described in the examples is, for example, 35% or more, preferably 55% or more, and particularly preferably 70% or more.

[0072] Since the sulfonium salt (1) has the above characteristics, it can be suitably used as an acid generator (e.g., a photoacid generator).

[0073] [Acid generator] The acid generator of the present invention contains at least a sulfonium salt (1). The acid generator may contain one kind of the sulfonium salt (1) alone, or may contain two or more kinds in combination. Further, the acid generator may contain components other than the sulfonium salt (1), but the proportion of the sulfonium salt (1) in all the compounds (100% by weight) contained in the acid generator that decompose upon light irradiation to generate an acid is preferably 50% by weight or more, more preferably 60% by weight or more, still more preferably 70% by weight or more, particularly preferably 80% by weight or more, most preferably 90% by weight or more, and especially preferably 95% by weight or more. That is, the acid generator of the present invention may contain an acid generator other than the sulfonium salt (1), but the content of other acid generators is preferably 50% by weight or less, more preferably 40% by weight or less, still more preferably 30% by weight or less, particularly preferably 20% by weight or less, most preferably 10% by weight or less, and especially preferably 5% by weight or less, based on all the compounds (100% by weight) contained in the acid generator that decompose upon light irradiation to generate an acid.

[0074] The acid generator has excellent solubility in an organic solvent, and its solubility in an organic solvent (for example, PGMEA) at room temperature (for example, 25 °C) and normal pressure is, for example, 2% by weight or more (for example, 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.

[0075] The acid generator is excellent in sensitivity not only to light rays on the longer wavelength side but also to extreme ultraviolet rays. When irradiated with the light rays, it easily decomposes to generate an acid (H + X - ).

[0076] Further, the acid generator is excellent in stability (or quencher resistance or base resistance), and decomposition is suppressed even when a quencher coexists under non-irradiation of the light rays. The residual ratio of the acid generator determined by the method described in the examples is, for example, 35% or more, preferably 55% or more, and particularly preferably 70% or more.

[0077] Therefore, the photoresist containing the acid generator and the quencher has excellent storage stability. And the preparation time of the photoresist is not limited to immediately before use, and it can be prepared in advance and used at any timing.

[0078] Since the acid generator has both the above characteristics, it can be suitably used as an acid generator for photoresists (particularly, an acid generator for photoresists used in photolithography utilizing light of ultra-short wavelengths).

[0079] [Photoresist] The photoresist of the present invention contains the acid generator (or sulfonium salt (1)) and an acid-reactive compound.

[0080] The content of the acid generator (or sulfonium salt (1)) is, for example, 0.001 to 20% by weight, preferably 0.01 to 15% by weight, particularly preferably 0.05 to 7% by weight of the total amount of the acid-reactive compound.

[0081] If the content of the acid generator (or sulfonium salt (1)) is 0.001% by weight or more of the total amount of the acid-reactive compound, excellent sensitivity can be exhibited not only to light of longer wavelengths but also to light of ultra-short wavelengths. Further, if the content is 20% by weight or less of the total amount of the acid-reactive compound, an effect of improving the resolution of the photoresist can be obtained.

[0082] (Acid-reactive compound) The acid-reactive compound is a compound whose solubility in an alkaline developer changes by the action of an acid. The photoresist of the present invention may contain one kind of the acid-reactive compound alone or a combination of two or more kinds.

[0083] The acid-reactive compounds include a negative photosensitive resin (QN) that is originally easily soluble in an alkaline developer and becomes hardly soluble or insoluble in the alkaline developer by the action of an acid, and a positive photosensitive resin (QP) that is originally hardly soluble or insoluble in an alkaline developer and becomes soluble in the alkaline developer by the action of an acid.

[0084] Therefore, the photoresist includes the following composition (1) and composition (2). Composition (1): A composition containing the acid generator and the negative photosensitive resin (QN) Composition (2): A composition containing the acid generator and the positive photosensitive resin (QP)

[0085] 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).

[0086] The phenolic hydroxyl group-containing resin (QN1) is a resin containing a phenolic hydroxyl group that shows easy solubility in an alkaline developer and becomes hardly soluble or insoluble in the alkaline developer by reacting with a crosslinking agent. Examples include novolak resins, polyhydroxystyrene, copolymers of hydroxystyrene, copolymers of hydroxystyrene and styrene, copolymers of hydroxystyrene and (meth)acrylic acid derivatives, phenol-xylene glycol condensation resins, cresol-xylene glycol condensation resins, polyimides containing phenolic hydroxyl groups, polyamic acids containing phenolic hydroxyl groups, phenol-dicyclopentadiene condensation resins, etc. These can be used alone or in combination of two or more.

[0087] The phenolic hydroxyl group-containing resin (QN1) may contain a phenolic low-molecular compound as a part of the components.

[0088] The polystyrene-reduced weight average molecular weight (Mw) of the phenolic hydroxyl group-containing resin (QN1) measured by GPC is, for example, 2000 to 20000.

[0089] The crosslinking agent (QN2) is a compound that can crosslink the phenolic hydroxyl group-containing resin (QN1) to insolubilize or make it insoluble by, for example, the acid generated from an acid generator. Examples thereof include bisphenol A-based epoxy compounds, bisphenol F-based epoxy compounds, bisphenol S-based epoxy compounds, novolak resin-based epoxy compounds, resol resin-based epoxy compounds, poly(hydroxystyrene)-based epoxy compounds, oxetane compounds, methylol group-containing melamine compounds, methylol group-containing benzoguanamine compounds, methylol group-containing urea compounds, methylol group-containing phenol compounds, alkoxyalkyl group-containing melamine compounds, alkoxyalkyl group-containing benzoguanamine compounds, alkoxyalkyl group-containing urea compounds, alkoxyalkyl group-containing phenol compounds, carboxymethyl group-containing melamine resins, carboxymethyl group-containing benzoguanamine resins, carboxymethyl group-containing urea resins, carboxymethyl group-containing phenol resins, carboxymethyl group-containing melamine compounds, carboxymethyl group-containing benzoguanamine compounds, carboxymethyl group-containing urea compounds, and carboxymethyl group-containing phenol compounds. These can be used alone or in combination of two or more.

[0090]

[0091] Examples of the positive photosensitive resin (or positive chemically amplified resin; QP) include an alkali-soluble resin (protecting group-introduced resin; QP1) into which an acid dissociable group is introduced as a protecting group.

[0092] The protecting group-introduced resin (QP1) is a resin in which some or all of the hydrogen atoms of the acidic functional groups (for example, phenolic hydroxyl groups, carboxyl groups, sulfonyl groups, etc.) in the alkali-soluble resin are substituted with acid dissociable groups.

[0093] ​The protecting group-introduced resin (QP1) is originally a resin that is insoluble or hardly soluble in an alkaline developer. When the acid-dissociable group dissociates by the acid (H + X - ) generated from the acid generator, it changes to an alkali-soluble resin that shows high solubility in an alkaline developer.

[0094] 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).

[0095] The alkali-soluble resin includes a phenolic hydroxyl group-containing resin, a carboxyl group-containing resin, and a sulfonic acid group-containing resin.

[0096] Examples of the phenolic hydroxyl group-containing resin include the same resins as the above-mentioned phenolic hydroxyl group-containing resin (QN1).

[0097] The carboxyl group-containing resin is not particularly limited as long as it is a polymer having a carboxyl group. For example, a homopolymer of a carboxyl group-containing vinyl monomer (Ba) or a copolymer of a carboxyl group-containing vinyl monomer (Ba) and a hydrophobic group-containing vinyl monomer (Bb) can be mentioned.

[0098] Examples of the carboxyl group-containing vinyl monomer (Ba) include (meth)acrylic acid.

[0099] Examples of the hydrophobic group-containing vinyl monomer (Bb) include C 1-20 (meth)acrylate esters (Bb1) such as alkyl (meth)acrylate and alicyclic group-containing (meth)acrylate, and hydrocarbon monomers having a styrene skeleton and aromatic hydrocarbon monomers (Bb2) such as vinylnaphthalene.

[0100] The sulfonic acid group-containing resin is not particularly limited as long as it is a polymer having a sulfonic acid group. For example, a copolymer of a sulfonic acid group-containing vinyl monomer (Bc) such as vinylsulfonic acid and styrenesulfonic acid and a hydrophobic group-containing vinyl monomer (Bb) can be mentioned.

[0101] Examples of the acid dissociable group of the protecting group-introduced resin (QP1) include 1-substituted methyl groups such as methoxymethyl group, benzyl group, tert-butoxycarbonylmethyl group; 1-substituted ethyl groups such as 1-methoxyethyl group, 1-ethoxyethyl group; 1-branched alkyl groups such as tert-butyl group; silyl groups such as trimethylsilyl group; germyl groups such as trimethylgermyl group; alkoxycarbonyl groups such as tert-butoxycarbonyl group; acyl groups; cyclic acid dissociable groups such as tetrahydropyranyl group, tetrahydrofuranyl group, tetrahydrothiopyranyl group, tetrahydrothiofuranyl group, etc. These may be contained alone or in combination of two or more.

[0102] The introduction rate of the acid dissociable group in the protecting group-introduced resin (QP1) {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 generally defined depending on the type of the acid dissociable group and the alkali-soluble resin into which the group is introduced, but is, for example, 10 to 100%, preferably 15 to 100%.

[0103] The polystyrene-reduced weight average molecular weight (Mw) of the protecting group-introduced resin (QP1) measured by GPC is, for example, 1000 to 150000, preferably 3000 to 100000.

[0104] (Other components) The photoresist of the present invention can contain one or more other components as necessary in addition to the above components. Examples of other components include quencher, organic solvent, pigment, dye, photosensitizer, dispersant, surfactant, filler, leveling agent, defoaming agent, antistatic agent, ultraviolet absorber, pH adjuster, surface modifier, plasticizer, drying accelerator, etc.

[0105] (Quencher) A quencher is a compound that suppresses the reduction of the pattern resolution of the resist film by neutralizing the acid generated from the acid generator in the resist film to prevent the acid from diffusing.

[0106] As the quencher, a basic substance can be used. Also, a salt that generates an acid with a lower acidity than the acid (H + X - ) generated from the acid generator can also be used as the quencher.

[0107] Examples of the basic substance include nitrogen-containing organic compounds such as amines and ammonium salts. These can be used alone or in combination of two or more.

[0108] Amines include aliphatic amines and aromatic amines.

[0109] Examples of aliphatic amines include primary amines such as hexylamine and octylamine; secondary amines such as dibutylamine, dipentylamine, and dihexylamine; and tertiary amines such as trimethylamine, tributylamine, trihexylamine, trioctylamine, N,N - diisopropylethylamine, and ethylenediamine.

[0110] Examples of aromatic amines include compounds in which an amino group is bonded to an aromatic hydrocarbon ring such as naphthylamine, aniline, and diisopropylaniline; and heteroaromatic amines such as pyridine, methylpyridine, and bipyridine.

[0111] Examples of ammonium salts include tetramethylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylammonium lactate.

[0112] As the quencher, an amine is preferred, and an aliphatic amine or an aromatic amine is particularly preferred.

[0113] From the viewpoint of improving the resolution of the photoresist, the content of the quencher is, for example, 0.01 to 50 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the acid generator (or sulfonium salt (1)) contained in the photoresist.

[0114] The content of the quencher is, from the viewpoint of improving the resolution of the photoresist, for example, 0.0005 to 10% by weight, preferably 0.005 to 5% by weight, of the total amount of the acid-reactive compound contained in the photoresist.

[0115] (organic solvent) As the organic solvent, any solvent that can dissolve the acid-reactive compound and impart good coatability to the photoresist may be used. Among them, it is preferable to use a solvent having a boiling point of 200°C or lower in that the photoresist can be easily dried after coating. Examples of such organic solvents include 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; and glycol monoether monoesters such as propylene glycol monomethyl ether acetate (PGMEA). These can be used alone or in combination of two or more.

[0116] The photoresist of the present invention can be prepared, for example, by dissolving the acid generator (or sulfonium salt (1)) in an organic solvent and mixing this with the acid-reactive compound.

[0117] The photoresist of the present invention contains the sulfonium salt (1) having high sensitivity to light rays of an ultra-short wavelength. Therefore, even when irradiating with light rays of an ultra-short wavelength, without containing a photosensitizer, in the exposed portion, acid (H + X - ) can be efficiently generated. And, due to the generated acid (H + X - ), the solubility of the acid-reactive compound in the exposed portion changes in the developer. When the acid-reactive compound is a negative photosensitive resin, the solubility decreases due to the acid (H + X - ). On the other hand, when the acid-reactive compound is a positive photosensitive resin, the acid (H + X -) increases solubility. Therefore, by using the photoresist of the present invention, an etching mask can be accurately formed by photolithography.

[0118] The photoresist of the present invention also contains a sulfonium salt (1) having quencher resistance. Therefore, it has excellent storage stability and exhibits excellent photosensitivity stably over a long period. Therefore, it can be prepared in advance and used at any timing.

[0119] [Method for manufacturing an electronic device or an optical device] The method for manufacturing an electronic device or an optical device of the present invention includes a step of forming a pattern by photolithography using the photoresist.

[0120] The step of forming a pattern by photolithography using the photoresist is preferably a step of forming an etching mask on a substrate through the following steps 1 to 3.

[0121] Step 1: A step of forming a coating film of the photoresist on a substrate Step 2: A step of performing light irradiation in a pattern shape on the coating film Step 3: A step of performing alkali development

[0122] (Step 1) This step is a step of forming a coating film of the photoresist on the substrate to be etched. The coating film can be formed by applying the photoresist to the substrate using a known method such as spin coating, curtain coating, roll coating, spray coating, screen printing, etc., and then drying it.

[0123] (Step 2) This step is a step of performing light irradiation in a pattern shape on the coating film obtained through Step 1 by a method such as light irradiation through a photomask having a pattern. As the light beam used for light irradiation, the sulfonium salt (1) is decomposed to form an acid (H + X -There is no particular limitation as long as can be generated, but from the perspective of forming a fine pattern, it is preferable to use light rays with an ultra-short wavelength such as EUV (extreme ultraviolet ray), EB (electron beam), or X-ray.

[0124] After light irradiation, heating at a temperature of 60 to 200 °C for about 0.1 to 120 minutes can increase the difference in solubility between the exposed part and the unexposed part in the alkaline developer, and is preferable in that the resolution of the pattern can be improved.

[0125] (Step 3) This step is a step of subjecting the photoresist coating film that has undergone Step 2 to an alkali development treatment.

[0126] Examples of the alkaline developer used for the alkali development treatment include an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, sodium hydrogen carbonate, an aqueous tetramethylammonium salt solution, and the like.

[0127] Methanol, ethanol, isopropyl alcohol, tetrahydrofuran, N-methylpyrrolidone, etc. may be added to the alkaline developer.

[0128] The alkali development treatment is performed, for example, by applying the alkaline developer to the coating film by a method such as a dip method, a shower method, or a spray method.

[0129] The temperature of the alkaline developer is, for example, 25 to 40 °C. Also, the alkali development time is appropriately determined according to the thickness of the coating film, but is, for example, about 1 to 5 minutes.

[0130] After Step 3, a resist film having a pattern can be formed on the substrate. If the substrate is etched using the resist film having a pattern thus obtained as an etching mask, an electronic device or an optical device having a high-precision wiring pattern or the like can be manufactured.

[0131] The electronic device includes, 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, microchannels, and inkjet heads, etc.

[0132] The optical device includes, for example, optical waveguides, metalenses, semiconductor lasers, etc.

[0133] As described above, each configuration of the present invention and their combinations, etc. are examples, and additions, omissions, substitutions, and changes of the configuration can be appropriately made without departing from the gist of the present invention. In addition, each aspect disclosed in this specification can be combined with any other features disclosed in this specification. Furthermore, the present disclosure is not limited by the embodiments.

Example

[0134] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited by these examples.

[0135] Example 1 (Preparation of Acid Generator and Photoresist) Using 96.5 g of 1-bromo-3,5-difluorobenzene, 13.4 g of magnesium, and 400 g of tetrahydrofuran, a tetrahydrofuran solution of 3,5-difluorophenylmagnesium bromide was prepared by a conventional method.

[0136] To the obtained tetrahydrofuran solution of 3,5-difluorophenylmagnesium bromide, a solution prepared by diluting 28.6 g of thionyl chloride with 50 g of tetrahydrofuran was added dropwise within a range where the system temperature did not exceed -5°C. After the addition was completed, the reaction was continued at room temperature for 1 hour to complete the reaction. This solution was added to 500 g of ion-exchanged water so that the temperature inside the system did not exceed 15°C, and stirred for 1 hour. Then, 300 g of ethyl acetate was added and stirred for 1 hour. After removing the aqueous layer, it was washed three times with 300 g of ion-exchanged water. The organic layer was desolvated, and the resulting brown residue was recrystallized from cyclohexane to obtain 26.0 g of bis(3,5-difluorophenyl)sulfoxide.

[0137] 6.86 g of the obtained bis(3,5-difluorophenyl)sulfoxide was dissolved in 20 g of dichloromethane together with 5.40 g of 3-iodoanisole, and 8.46 g of trifluoromethanesulfonic anhydride was added dropwise within the range that the temperature inside the system did not exceed -5°C. After completion of the dropwise addition, 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. These crystals were separated by filtration, dissolved in 30 g of dichloromethane, and 100 g of a 17% dichloromethane solution of boron tribromide was added dropwise within the range that the temperature inside the system did not exceed 10°C. After completion of the dropwise addition, the reaction was continued at room temperature for 1 hour to complete the reaction. Then, 50 g of ion-exchanged water was added to the reaction solution, neutralized with sodium hydrogen carbonate, the aqueous layer was removed, and the organic layer was further washed three times with 50 g of ion-exchanged water.

[0138] The washed organic layer was desolvated to obtain crude crystals, which were purified by silica gel column chromatography to obtain 7.18 g of a sulfonium salt [acid generator (1)] which is a salt of the cation and anion described in the following table.

[0139] 1 part by weight of the obtained acid generator (1) and 100 parts by weight of a copolymer of p-hydroxystyrene and tert-butyl acrylate as an acid-reactive compound were uniformly dissolved in PGMEA and filtered through a membrane filter with a pore size of 1 μm to obtain a photoresist (1).

[0140] Examples 2 to 13, Comparative Examples 1 to 5 Acid generators described in the following table were obtained in the same manner as in Example 1. A photoresist was obtained in the same manner as in Example 1, except that the acid generator obtained by replacing the acid generator (1) was used.

[0141] (Evaluation) The photosensitivity, solvent solubility, and quencher resistance of the acid generators of the examples and comparative examples were evaluated by the following methods. Also, the alkali developability of the photoresists of the examples and comparative examples was evaluated by the following method. The results are shown in the table below.

[0142] <Photosensitivity> The acid generator was diluted with acetonitrile so that the molar concentration was 2.5 mM, and rhodamine B base (an acid color reagent, manufactured by Sigma-Aldrich) was added so that the molar concentration was 2.5 mM to obtain a sample solution.

[0143] The obtained sample solution was placed in a quartz cell with an optical path length of 1 cm, and using an EB exposure apparatus (JEOL JBX-9300, manufactured by JEOL Ltd.), electron beam exposure was performed under the conditions of an acceleration voltage of 100 kV and an integrated light quantity of 100 μC / cm 2 of. When the acid generator in the sample solution decomposes upon exposure to generate an acid, the generated acid reacts with the rhodamine B base and the absorbance at 556 nm increases. Therefore, by measuring the absorbance at 556 nm after exposure, the amount of acid generated can be determined. The absorbance was measured using a spectrophotometer (UV-vis). From the absorbance at 556 nm of the sample solution after exposure, the acid concentration in the sample solution after exposure was quantified using a calibration curve (standard substance: p-toluenesulfonic acid). The acid generation rate was calculated from the following formula, and the photosensitivity was evaluated according to the following criteria from the obtained acid generation rate. Acid generation rate (%) = Acid concentration (mM) after exposure / Acid generator concentration (mM) before exposure × 100

[0144] (Evaluation criteria) Excellent (◎): Acid generation rate is 50% or more Good (○): Acid generation rate is 40% or more and less than 50% Fair (△): Acid generation rate is 20% or more and less than 40% Not acceptable (×): Acid generation rate is less than 20%

[0145] <Solvent solubility> Charge 0.1 g of the acid generator into a test tube, and add 0.2 g of PGMEA at a time under normal pressure and at a temperature of 25 °C until the acid generator is completely dissolved. Determine the concentration of the acid generator when it is completely dissolved, and evaluate the solvent solubility according to the following criteria. (Evaluation criteria) Good (◎): Acid generator concentration is 5 wt% or more Acceptable (○): Acid generator concentration is 2 wt% or more and less than 5 wt% Not acceptable (×): Acid generator concentration is less than 2 wt%

[0146] <Quencher resistance> Prepare a 5% solution of the acid generator in propylene glycol monomethyl ether, add an equimolar amount of tetramethylammonium hydroxide (10% solution) to the acid generator, shake well to obtain a test solution. Immediately after preparing the test solution, sample 0.05 g, dilute it 50 times, and subject it to HPLC analysis to record the initial area (Ar1) of the acid generator. Also, after storing the test solution at room temperature for 1 day, perform HPLC analysis in the same manner as above to record the area (Ar2) of the acid generator after storage. Then, calculate the residual rate of the acid generator from the following formula and evaluate the quencher resistance according to the following criteria. Residual rate of acid generator (%) = [Ar2 / Ar1] × 100 Note that the higher the residual rate of the acid generator, the more stable it is to the basic component of the quencher and the higher the quencher resistance. (Evaluation criteria) Excellent (◎): Residual rate of acid generator is 70% or more Good (○): Residual rate of acid generator is 55% or more and less than 70% Acceptable (△): Residual rate of acid generator is 35% or more and less than 55% Not acceptable (×): Residual rate of acid generator is less than 35%

[0147] <Alkaline developability> A photoresist was spin-coated (rotation speed: 700 rpm, 20 seconds) on a glass plate, heated on a hot plate at 85°C for 10 minutes, and then heated on a hot plate at 120°C for 10 minutes to obtain a resist film. The obtained resist film was exposed using an exposure apparatus (high-pressure mercury lamp, mask aligner MA-10) through a pattern mask in a grid shape with a line width of 100 μm at an integrated light quantity of 1000 mJ / cm 2 . After air cooling for 5 minutes, it was immersed in an alkaline developer (2.38% aqueous solution of TMAH) for 360 seconds. Then, it was washed with water and heated on a hot plate at 80°C for 30 minutes. As a result, an evaluation sample having a pattern with a line width of 100 μm and a film thickness of 50 μm was obtained. The obtained evaluation sample was visually observed and further observed using a scanning electron microscope to confirm the pattern shape and the degree of resin remaining after development. Then, the alkali developability was evaluated according to the following criteria. (Evaluation Criteria) Good (○): No remaining dissolution, capable of forming a uniform pattern Fair (△): Local remaining dissolution exists, but capable of forming a uniform pattern Poor (×): Extensive remaining dissolution exists, incapable of forming a uniform pattern

[0148] [Table 1]

[0149] [Table 2]

[0150] [Table 3]

[0151] From Tables 1 to 3, since the acid generator (or sulfonium salt (1)) of the present invention has the three types of groups of the following [1], [2], and [3] in combination, it has high sensitivity to light rays of an extremely short wavelength, and moreover, it can be seen that it is excellent in solvent solubility and quencher resistance. [1] A fluorine atom or a fluoroalkyl group [2] An iodine atom [3] A group selected from a hydroxy group, a hydroxyalkyl group, an alkoxy group, and a carboxyl group

[0152] Since the acid generator (or sulfonium salt (1)) of the present invention has excellent solvent solubility, quencher resistance, and photosensitivity as described above, it can be suitably used as an acid generator for a photoresist (particularly, an acid generator for a photoresist used in photolithography using light rays of an extremely short wavelength). When photolithography (particularly, photolithography using light rays of an extremely short wavelength) is performed using a photoresist containing the acid generator (or sulfonium salt (1)) of the present invention, it can be seen that a fine pattern can be accurately formed, and a large capacity and miniaturization of an electronic device or an optical device can be realized.

[0153] On the other hand, from Comparative Example 1, it can be seen that in the case of a sulfonium salt having none of the groups of [1], [2], and [3] in the cation, the sensitivity to light rays of an extremely short wavelength, the solvent solubility, and the alkali developability are all low. Further, from Comparative Example 3, it can be seen that in the case of a sulfonium salt having the groups of [1] and [2] in the cation and not having the group of [3], the sensitivity to light rays of an extremely short wavelength is high, but the solvent solubility and the alkali developability are low. Furthermore, in the case of a sulfonium salt having the group of [1] in the cation and not having the group of [2], it can be seen that the solvent solubility is high, but the sensitivity to light rays of an extremely short wavelength and the alkali developability are low.

[0154] Furthermore, when Comparative Example 5 is compared with the Examples, the sulfonium salt containing a fluorine atom or a fluoroalkyl group at the ortho- or meta-position (particularly, the meta-position) with respect to the position where the sulfur atom is bonded is significantly inferior in quencher resistance compared to the sulfonium salt (1) of the present application containing a fluorine atom or a fluoroalkyl group at the para-position with respect to the position where the sulfur atom is bonded.

Claims

1. A sulfonium salt represented by the following formula (1): 【Chemistry 1】 (wherein, Rf １ , Rf ２ , Rf １１ and Rf １２ R may be the same or different and represents a fluorine atom or a fluoroalkyl group. ａ represents a hydroxy group, a hydroxyalkyl group, an alkoxy group, or a carboxyl group. m and n each represent an integer of 1 or more, provided that m+n is an integer of 5 or less. The benzene ring in the formula may have a substituent bonded thereto in addition to the above groups. X － indicates a monovalent counter anion)

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

3. An acid generator comprising the sulfonium salt according to claim 1 or 2.

4. A photoresist comprising the acid generator of claim 3 and an acid-reactive compound.

5. A method for producing an electronic device or an optical device, comprising the step of forming a pattern by photolithography using the photoresist according to claim 4.

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