Methods for stabilizing a photoactive generator

Abstract

The present application relates to methods for stabilizing a photoacid generator in a photoresist composition, photoresist compositions, and uses of photoresist compositions.

Description

METHODS FOR STABILIZING A PHOTOACTIVE GENERATORFIELD OF THE INVENTION

[0001] The present application relates to methods for stabilizing a photoacid generator in a photoresist composition, photoresist compositions, and uses of photoresist compositions.BACKGROUND OF THE INVENTION

[0002] When attempting to form a fine pattern by lithography method, a high resolution is required for the resist material. To meet such a demand, a chemically amplified resist composition comprising a base resin and a photoacid generator is used.

[0003] For example, a chemically amplified positive type resist composition comprises a resin component, solubility of which in an alkali aqueous solution increases by the action of an acid, and a photoacid generator which generates an acid when exposed to light. Upon forming a resist pattern, when the acid is generated by the photoacid generator, the exposed portion becomes alkali-soluble.

[0004] Patent Document 1 studies a process for producing a resist composition, comprising the steps of: preparing an organic solvent (S) using ethyl lactate that comprises an antioxidant, so that a concentration of said antioxidant within said organic solvent (S) is 10 ppm or greater, and dissolving a base material component in said organic solvent (S).

[0005] Patent Document 2 studies a method, comprising: providing a layered structure comprising a resist layer disposed on a surface of a substrate, the resist layer comprising the PAG polymer of claim 13; pattern-wise exposing the resist layer to radiation, thereby forming an exposed resist layer;baking the exposed resist layer at about 90 degrees centigrade to about 130 degrees centigrade for at least 1 second, thereby forming a treated resist layer; and selectively removing a region of the treated resist layer using a developer, thereby forming a patterned resist layer.PRIOR ART DOCUMENTSPATENT DOCUMENTS

[0006] [Patent document 1] US 2009-155713 A[Patent document 2] US 2018-044459 ASUMMARY OF THE INVENTION

[0007] The inventors newly have found that there are still one or more of considerable problems for which improvement is desired, as listed below: A photoacid generator in a photoresist composition is decomposed, a photoacid generator decomposes due to the reaction between a photoacid generator and a solvent; a photoacid generator decomposes due to the reaction between a photoacid generator and a quencher under the existence of an amine without UV irradiation; when bottom anti-reflective coating is not formed, standing wave in a resist pattern is reduced; a resist pattern width is not uniform; rectangularity of a resist pattern is insufficient; resolution of a resist pattern is insufficient; heat resistance of a resist pattern is insufficient; and efficiency of manufacturing process is insufficient.

[0008] The inventors have found that these problems can be solved by providing methods as disclosed and claimed hereinafter.

[0009] The invention relates to a method for stabilizing a photoacid generator in a photoresist composition comprising, essentially consisting of or consisting of, step (a);(a) mixing multiple compounds to form a photoresist composition, wherein the multiple compounds comprise a polymer, a photoacid generator, and a compound A represented by formula (I);wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy, preferably C1-20 alkyl, more preferably C1-10 alkyl; wherein R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy, preferably H or C1-20 alkyl, more preferably H or C1-10 alkyl; when R1to R5are each independently an alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO— 0— , — 0— CO— , — 0— CO— 0— , — CR CR— or — CEC— ; wherein R3and R4may form a mono- or polycyclic organic ring system with each other.

[0010] The invention further relates to a photoresist composition comprising; essentially consisting of or consisting of, a polymer, a photoacid generator and a compound A represented by formula (I); the molar ratio of the compound A to the photoacid generator is in the range from 0.05 to 3, preferably 0.06 to 1 .5, more preferably 0.07 to 0.5;wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy, preferably C1-20 alkyl, more preferably C1-10 alkyl;R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy, preferably H or C1-20 alkyl, more preferably H or C1-10 alkyl; when R1to R5are each independently an alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO— 0— , — 0— CO— , — 0— CO— 0— , — CR CR— or — CEC— ; wherein R3and R4may form a mono- or polycyclic organic ring system with each other.

[0011] The invention furthermore relates to use of a compound A represented by formula (I) for stabilizing a photoacid generator in a photoresist composition;wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy, preferably C1-20 alkyl, more preferably C1-10 alkyl;R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy, preferably H or C1-20 alkyl, more preferably H or C1-10 alkyl; when R1to R5are each independently an alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO— 0— , — 0— CO— , — 0— CO— 0— , — CR CR— or — CEC— ; wherein R3and R4may form a mono- or polycyclic organic ring system with each other.TECHNICAL EFFECTS OF THE INVENTION

[0012] The present invention may provide one or more of the following effects: Decomposition of a photoacid generator in a photoresist composition is suppressed, reaction between a photoacid generator and a solvent that results in a decomposition of the photoacid generator is suppressed; reaction between a photoacid generator and a solvent that results in decomposition of the photoacid generator under the existence of an amine is suppressed; reaction between a photoacid generator and a solvent that results in a decomposition of the photoacid generator under the existence of a tertiary amine is suppressed; even when bottom anti-reflective coating is not formed, effect of reducing standing wave in a resist pattern is sufficient; a resist pattern width is uniform; rectangularity of a resist pattern is sufficient; resolution of a resist pattern is sufficient; heat resistance of the resist pattern is sufficient; and efficiency of manufacturing process is sufficient.

[0013] [Definition of the terms]Unless otherwise specified in the present specification, the definitions and examples described in this paragraph are followed.

[0014] The singular form includes the plural form and “one” or “that” means “at least one”. An element of a concept can be expressed by a plurality of species, and when the amount (for example, mass % or mol%) is described, it means sum of the plurality of species. “And / or” includes a combination of all elements and also includes single use of the element.

[0015] When a numerical range is indicated using “to” or it includes both endpoints and units thereof are common. For example, 5 to 25 mol% means 5 mol% or more and 25 mol% or less.

[0016] The descriptions such as “Cx-y”, “Cx-Cy” and “Cx” mean the number of carbons in a molecule or substituent. For example, C1-6 alkyl means an alkyl chain having 1 or more and 6 or less carbons (methyl, ethyl, propyl, butyl, pentyl, hexyl etc.).

[0017] When a polymer has a plural type of repeating units, these repeating units copolymerize. The copolymerization of these repeating units is any of alternating copolymerization, random copolymerization, block copolymerization, graft copolymerization, or a mixture thereof. When polymer or resin is represented by a structural formula, n, m or the like that is attached next to parentheses indicate the number of repetitions.

[0018] Celsius is used as the temperature unit. For example, 20 degrees means 20 degrees Celsius.

[0019] The additive refers to a compound itself having a function thereof (for example, in the case of a base generator, a compound itself that generates a base). An embodiment in which the compound is dissolved or dispersed in a solvent and added to a composition is also possible. As one embodiment of the present invention, it is preferable that such a solvent is contained in the composition according to the present invention as the solvent © or another component.DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention are described in detail.

[0021] [Method for stabilizing a photoacid generator in a photoresist composition]The method of stabilizing a photoacid generator in a photoresist composition according to the present invention (hereafter referred to as the method) comprises, essentially consists of or consists of, step (a);(a) mixing multiple compounds to form a photoresist composition, wherein the multiple compounds comprise a polymer, a photoacid generator, and a compound A represented by formula (I);wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy;R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy; when R1to R5are each independently an alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO— 0— , — 0— CO— — 0— CO— 0— , — CR CR— or — CEC— ; wherein R3and R4may form a mono- or polycyclic organic ring system with each other.

[0022] Step (a)In step (a), the multiple compounds may be mixed without adhering to a specific order. The multiple compounds may be mixed with or without a solvent.

[0023] In some embodiments of the present invention, the step (a) contains, essentially consists of or consists of, the following steps in this order.(a1 ) mixing the polymer with the photoacid generator to form a first mixture, and(a2) mixing the first mixture obtained in the step (a1 ) with the compound A represented by the formula (I).

[0024] In some embodiments of the present invention, the step (a) contains, essentially consists of or consists of, the following steps in this order.(a1 ) mixing the polymer with the compound A represented by the formula (I) to form a first mixture, and(a2) mixing the first mixture obtained in the step (a1 ) with the photoacid generator.

[0025] In some embodiments of the present invention, the step (a) contains, essentially consists of or consists of, the following steps in this order.(a1 ) mixing the compound A represented by the formula (I) with the photoacid generator to form a first mixture, and(a2) mixing the first mixture obtained in the step (a1 ) with the polymer.

[0026] In some embodiments of the present invention, the step (a) contains, essentially consists of or consists of, the following steps in this order.(a1 ) mixing the polymer, the photoacid generator, and the compound A represented by the formula (I) at the same time.

[0027] According to the present invention, preferably at least the photoacid generator and the compound A are first mixed in the step (a1 ). In said preferable embodiment, the rest of the compounds may be mixed either together with or separately from the photoacid generator and the compound A without adhering to a specific order.

[0028] This is not bound by theory, but it is believed that by first mixing at least the photoacid generator and the compound A, the decomposition of the photoacid generator is more sufficiently suppressed.

[0029] In another preferable embodiment, at least the photoacid generator and the compound A may be first mixed with a solvent separately to form a photoacid generator solution and a compound A solution.In another preferable embodiment, at least the photoacid generator and the compound A may be first mixed with a solvent at the same time to form a first mixture.

[0030] This is not bound by theory, but it is believed that by first mixing at least the photoacid generator and the compound A with a solvent, the photoacid generator and the compound A are more sufficiently mixed. Thus, it is believed that the decomposition of the photoacid generator is rmore sufficiently suppressed.

[0031] Thus, the step (a1 ) may contain the following steps (aT) and (a2’) or the following step (a1”).(aT) mixing at least the photoacid generator and the compound A with a solvent separately to form a photoacid generator solution and a compound A solution, and(a2’) mixing at least the photoacid generator solution and the compound A solution to form a first mixture.(a1”) mixing at least the photoacid generator and the compound A with a solvent at the same time to form a first mixture.

[0032] One or more compounds other than the polymer, the photoacid generator, and the compound A represented by the formula (I) (hereafter, referred to as other compounds) may be included in the multiple compounds and mixed with the polymer, the photoacid generator, and the compound A represented by the formula (I). Other compounds may be mixed without adhering to a specific order.

[0033] The multiple compounds may be mixed by well-known processes such as stirring the multiple compounds with a rod or an agitator having a paddle, a propeller or a turbine. One or more compounds included in the multiple compounds may be added to another compound or a mixture of two or more compounds dropwise intermittently over a predetermined time at a temperature in a certain range. The temperature while mixing may be raised or lowered at moderate timings.

[0034] The predetermined time is preferably in the range from 1 to 120 min, more preferably 1 to 90 min, very preferably 1 to 60 min, furthermore preferably 1 to 30 min. The range of temperature is preferably from 1 to 90 °C, more preferably from 5 to 60 °C, very preferably from 10 to 40 °C, furthermore preferably from 15 to 30 °C.

[0035] Compound AThe multiple compounds contain the compound A. The compound A is represented by formula (I);wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy, preferably linear, branched or cyclic structure containing C1-20 alkyl or linear, branched or cyclic structure containing C1-20 alkoxyl, more preferably linear or branched C1-10 alkyl, very preferably branched C1-5 alkyl.R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy, preferably H, linear, branched or cyclic structure containing C1-20 alkyl or linear, branched or cyclic structure containing C1-20 alkoxy, more preferably H or linear or branched C1-10 alkyl, very preferably H or linear C1-5 alkyl, most preferably H or methyl.When R1to R5are each independently alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — O — , — S — , — CO — , — CO— O— , — O— CO— , — O— CO— O— , — CR CR— or — C^C— .R3and R4may form a mono- or polycyclic organic ring system with each other.

[0036] Preferably at least one of R1, R3and R5is linear, branched or cyclic structure containing C1-20 alkyl, more preferably at least one of R1, R3and R5is linear or branched C1-10 alkyl, very preferably R1, R3and R5are linear or branched C1-5 alkyl.

[0037] Preferably at least one of R2and R4is H, more preferably R2and R4are H.

[0038] This is not bound by theory, but it is considered that the compound A suppressed the decomposition of the photoacid generator by capturing radicals that induces the decomposition.

[0039] The molar ratio of the compound A to the photoacid generator is in the range from 0.05 to 3, preferably 0.06 to 1 .5, more preferably 0.07 to 0.5.

[0040] This is not bound by theory, but it is considered that the compound A further sufficiently suppresses the decomposition of the photoacid generator when the molar ratio of the compound A to the photoacid generator is in the above-mentioned range.

[0041] The molecular weight of the compound A is preferably in the range from 10 to 1 ,000, more preferably 30 to 800, very preferably 50 to 500, and most preferably 100 to 300.

[0042] The content of the compound A is preferably in the range from 0.05 to 5 mass parts, more preferably 0.1 to 3 mass parts, very preferably 0.2 to 1 .5 mass parts based on 100 mass parts of the polymer.

[0043] Exemplified embodiments of the polymer include the following.

[0044] Photoacid generatorThe multiple compounds contain a photoacid generator. In a preferred embodiment, the photoacid generator is represented by formula (A-1 ). Bn+cation Bn-anion (A-1 ) wherein Bn+cation is preferably a cation represented by the formula (AC1 ), a cation represented by the formula (AC2), or a cation represented by the formula (AC3). Bn+cation is n valent as a whole, n is 1 to 3, preferably 1 or 2, more preferably 1 .

[0045] Bn-anion is preferably an anion represented by the formula (AA1 ), an anion represented by the formula (AA2), or an anion represented by the formula (AA3).Bn_anion is n valent as a whole, n is 1 to 3, preferably 1 or 2, more preferably 1 .

[0046] The formula (AC1 ) is as follows;wherein R1and R2are each independently C1-20 alkyl, C1-20 aryl or C1-20 aralkyl, preferably linear, branched or cyclic structure containing C1-20 alkyl, C1-20 aryl or C1-20 aralkyl, more preferably C1-15 aryl or C1-15 aralkyl, very preferably C1-10 aryl.

[0047] Preferably, a cation represented by the formula (AC1 ) may also be represented by formula (AC1 -1 );wherein Ra1and Ra2are each independently linear, branched or cyclic structure containing C1-6 alkyl, linear, branched or cyclic structure containing C1-6 alkoxy or C6-12 aryl, preferably branched C4-6 alkyl, more preferably t- butyl or 1 ,1 -dimethylpropyl, very preferably t-butyl. na1 and na2 are each independently 0, 1 , 2 or 3, preferably each 1 .

[0048] Exemplified embodiments of the formula (AC1 ) are as follows.

[0049] The formula (AC2) is as follows;wherein Ra3to Ra5are each independently linear, branched or cyclic structure containing C1-6 alkyl, linear, branched or cyclic structure containing C1-6 alkoxy, C6-12 aryl, C6-12 arylthio or C6-12 aryloxy, preferably methyl, ethyl, t- butyl, methoxy, ethoxy, phenylthio or phenyloxy, more preferably t-butyl, methoxy, ethoxy, phenylthio or phenyloxy. na3 to na5 are each independently 0, 1 , 2 or 3. It is also a preferred embodiment that na3 to na5 are all 1 and Ra3to Ra5are all identical. It is also a preferred embodiment that na3 to na5 are all 0.

[0050] Exemplified embodiments of the formula (AC2) are as follows.wherein Ra6is each independently linear, branched or cyclic structure containing C1-6 alkyl, linear, branched or cyclic structure containing C1-6 alkoxy or C6-12 aryl, preferably methyl, ethyl, methoxy or ethoxy, more preferably methyl or methoxy.Ra7and Ra8are each independently linear, branched or cyclic structure containing C1-6 alkyl, preferably methyl, ethyl or linear butyl, more preferably methyl. na6 to na8 are each independently 0, 1 , 2 or 3; more preferably 1 or 3.

[0052] Exemplified embodiment of the formula (AC3) are as follows.

[0053] The formula (AA1 ) is as follows:wherein Ra9is linear, branched or cyclic structure containing C1-6 fluorinesubstituted alkyl, linear, branched or cyclic structure containing C1-6 fluorinesubstituted alkoxy, C6-12 fluorine-substituted aryl, C2-12 fluorine-substituted acyl or C6-12 fluorine-substituted alkoxyaryl, preferably linear, branched or cyclic structure containing C2-6 fluorine-substituted alkyl or C6-10 fluorine- substituted aryl, more preferably linear C2-4 fluorine-substituted alkyl or Ce-8 fluorine-substituted aryl, very preferably linear C4 fluorine-substituted alkyl or C7 fluorine-substituted aryl. In the fluorine-substituted alkyl of Ra9, an embodiment in which all the hydrogen present in the alkyl moiety are substituted with fluorine is preferable (hereafter, the state where all the hydrogen of a group are substituted with fluorine is referred to as “fully fluorine-substituted”) .Ra9is preferably fully fluorine-substituted methyl, ethyl, propyl, butyl, pentyl or toluene where methyl is fully fluorine-substituted, more preferably fully fluorinated propyl, butyl, pentyl or toluene where methyl is fully fluorine- substituted, very preferably fully fluorinated butyl or toluene where methyl is fully fluorine-substituted.na9 is 1 or 2, preferably 1 . When na9 is 2, Ra9becomes divalent, and hydrogen or fluorine of Ra9becomes a single bond and is bonded to an S atom.

[0054] Exemplified embodiments of the formula (AA1 ) are as follows.CFsSOs", CsFySOs", C4FgSO3',Ra1° to Ra12are each independently linear, branched or cyclic structure containing C1-6 fluorine-substituted alkyl, linear, branched or cyclic structure containing C1-6 fluorine-substituted alkoxy, linear, branched or cyclic structure containing C1-6 alkyl, preferably linear, branched or cyclic structure containingC1-6 fully fluorine-substituted alkyl, more preferably linear or branched C1-6 fully fluorine-substituted alkyl, very preferably fully fluorine-substituted methyl, ethyl, or t-butyl, most preferably fully fluorine-substituted methyl.

[0056] An exemplified embodiment of the formula (AA2) is as follows.

[0057] The formula (AA3) is as follows:Ra13is linear, branched or cyclic structure containing C1-6 alkylene or C6-12 arylene, preferably methylene, ethylene, propylene or butylene, more preferably methylene or ethylene, very preferably methylene. na13 is 0 or 1 , preferably 0. na23 is 1 , 2 or 3, preferably 1 or 2, more preferably 1 .

[0058] Exemplified embodiments of the formula (AA3) are as follows.

[0059] The photoacid generator may also be represented by formula (AD).Rna14and Rna15are each independently linear, branched or cyclic structure containing C1-6 alkyl or C6-12 aryl, preferably linear, branched or cyclic structure containing C2-6 alkyl or C6-10 aryl, more preferably branched or cyclic structure containing C4-6 alkyl or C6-8 aryl.

[0060] Exemplified embodiments of the formula (AD) are as follows.

[0061] The photoacid generator preferably comprises a cation represented by the formula (AC1 ) or (AC2) and an anion represented by the formula (AA1 ) or (AA3).

[0062] The photoacid generator of the present invention may be selected from one or more members of the following group consisting of the photoacid generator consisting of the cation represented by the formula (AC1 ) and the anion represented by the formula (AA1 ), the photoacid generator consisting of the cation represented by the formula (AC1 ) and the anion represented by the formula (AA2), the photoacid generator consisting of the cation represented by the formula (AC1 ) and the anion represented by the formula (AA3), the photoacid generator consisting of the cation represented by the formula (AC2) and the anion represented by the formula (AA1 ), the photoacid generator consisting of the cation represented by the formula (AC2) and the anion represented by the formula (AA2), the photoacid generator consisting of the cation represented by the formula (AC2) and the anion represented by the formula (AA3), the photoacid generator consisting of the cation represented by the formula (AC3) and the anion represented by the formula (AA1 ), the photoacid generator consisting of the cation represented by the formula (AC3) and the anion represented by the formula (AA2), the photoacid generator consisting of the cation represented by the formula (AC3) and the anion represented by the formula (AA3), and the photoacid generator represented by the formula (AD).

[0063] The content of the photoacid generator is preferably in the range from 1 to 10 mass parts, more preferably 2 to 7 mass parts, very preferably 2.5 to 5 mass parts based on 100 mass parts of the polymer.

[0064] The weight average molecular weight of the photoacid generator is preferably in the range from 30 to 1 ,000, more preferably 100 to 800, very preferably 150 to 600, most preferably 200 to 500.

[0065] PolymerThe multiple compounds contain a polymer, the polymer comprises at least one of the following repeating units (A-1 ) to (A-4);wherein R11, R21, R41and R45are each independently C1-10 alkyl, preferably linear, branched or cyclic structure containing C1-10 alkyl, more preferably linear, branched or cyclic structure containing C1-6 alkyl, very preferably linear or branched C1-6 alkyl.One or more of non-adjacent CH2-groups of R11, R21, R41and R45are optionally replaced by -O-.R12, R13, R14, R22, R23, R24, R31, R32, R33, R34, R42, R43and R44are each independently H, C1-5 alkyl, C1-5 alkoxy or -COOH, preferably H, linear, branched or cyclic structure containing C1-5 alkyl, linear, branched or cyclic structure containing C1-5 alkoxy or -COOH, more preferably H, linear, branched or cyclic structure containing C1-5 alkyl, very preferably H or tertbutyl. p11 is 0 to 4, preferably 0 to 2, more preferably 0. p15 is 0 to 2, preferably 1 . p11 + p15 ≤ 5 is satisfied. p21 is 0 to 4, preferably 0 to 2, more preferably 0. p41 is 0 to 4, preferably 0 to 2, more preferably 0. p45 is 1 to 2, preferably 1 . p41 + p45 ≤ 5 is satisfied.

[0066] Exemplified embodiment of the formula (A-1 ) includes the following.

[0067] Exemplified embodiment of the formula (A-2) includes the following.

[0068] Exemplified embodiments of the formula (A-3) include the followings.

[0069] Exemplified embodiments of the formula (A-4) include the followings.

[0070] The polymer may comprise plural kinds of repeating units represented by the formula (A-1 ), (A-2), (A-3) or (A-4). For example, it is possible for the polymer to have a repeating unit (A-1 ) where p15 = 1 and a repeating unit (A- 1 ) where p15 = 2 at a ratio of 1 : 1 . In this case, it becomes p15 = 1 .5 as a whole.

[0071] These structural units are appropriately blended according to the purpose. It is a preferred embodiment that the structural units are blended so that an increase rate of solubility in the alkaline aqueous solution becomes appropriate by the acid.

[0072] nA-i, nA-2, nA-3 and nA-4, which are the numbers of repeating units represented by the formulae (A-1 ), (A-2), (A-3) and (A-4) in the polymer (A), are described below.

[0073] nA-i / (nA-i + nA-2 + nA-3 + nA-4) is preferably 40 to 80%; more preferably 45 to 75%, very preferably 50 to 70%; and most preferably 55 to 65%. nA-2 / (nA-i + nA-2 + nA-3 + nA-4) is preferably 0 to 40%; more preferably 0 to 35%; very preferably 5 to 35%; and most preferably 15 to 25%. nA-3 / (nA-i + nA-2 + nA-3 + nA-4) is preferably 0 to 40%; more preferably 10 to 40%; very preferably 15 to 30%; and most preferably 15 to 25%. nA-4 / (nA-i + nA-2 + nA-3 + nA-4) is preferably 0 to 40%; more preferably 10 to 40%; very preferably 15 to 30%; and most preferably 15 to 25%.As an embodiment of the present invention, when nA-3 > 0, nA-4 = 0.

[0074] The polymer may be selected from one or more of the polymers comprising at least one of the repeating units (A-1 ) to (A-4).

[0075] The polymer may also comprise one or more additional repeating units other than the repeating units represented by the formulae (A-1 ), (A-2), (A-3) and (A-4). ntotai, which is the total number of all repeating units included in the polymer, satisfies the following.(nA-i + nA-2 + nA-3 + nA-4) / ntotai = preferably 80 to 100%, more preferably 90 to 100%, and very preferably 95 to 100%. It is also a preferred embodiment of the polymer to include no further repeating unit ((nA-i + nA-2 + nA-3 + nA-4) / ntotai = 100%).

[0076] Exemplified embodiments of the polymer include the following.

[0077] The content of the polymer is preferably in the range from 40 to 99 mass %, more preferably 60 to 98 mass %, very preferably 70 to 97 mass %, and most preferably 80 to 96 mass % based on the content of the compounds other than the solvent.

[0078] The weight average molecular weight (hereinafter referred to as Mw in some cases) of the polymer is preferably in the range from 2,000 to 50,000; more preferably 4,000 to 40,000, very preferably 6,000 to 30,000; and most preferably 8,000 to 20,000.

[0079] In the present invention, Mw can be measured by gel permeation chromatography (GPC). In the measurement, it is a preferable example that a GPC column at 40 degrees Celsius, an elution solvent of tetrahydrofuran at 0.6 mL / min and monodisperse polystyrene as a standard are used.

[0080] The multiple compounds may include one or more additional polymers that do not comprise repeating units represented by the formulae (A-1 ), (A-2), (A-3) and (A-4). The content of the additional polymers is preferably in the range from 0 to 10 mass %, more preferably 0 to 5 mass %, very preferably 0 to 1 mass %, and most preferably 0 mass % (not included) based on the content of the compounds other than the solvent.

[0081] AmineThe multiple compounds may contain an amine. In a preferred embodiment, the amine is selected from one or more members of the following group consisting of a primary amine, a secondary amine and a tertiary amine. More preferably said amine is a tertiary amine.

[0082] The primary amine may be selected from one or more members of the following group consisting of ethylamine, propylamine, butylamine, 2- ethylhexylamine, octylamine, and dodecylamine, n-octylamine, n-decylamine,n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine and oleylamine.

[0083] The secondary amine may be selected from one or more members of the following group consisting of dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, bis-2- ethylhexylamine, methylethylamine, ethylbutylamine, N-methyl-1 -amino- cyclohexane, ethylamylamine, piperidine, piperazine and morpholine.

[0084] The tertiary amine may be selected from one or more members of the following group consisting of trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n- octylamine, tri-n-nonylamine, tri-n-decanylamine and tri-n-dodecylamine, more preferably selected from one or more members of the following group consisting of the group consisting of tri-n-heptylamine, tri-n-octylamine and tri-n-nonylamine.

[0085] The content of the amine is preferably in the range from 0.1 to 1 mass parts, more preferably 0.2 to 0.9 mass parts, very preferably 0.3 to 0.8 mass parts based on 100 mass parts of the polymer.

[0086] The molecular weight of the amine is preferably in the range from 30 to 1 ,000 more preferably 100 to 800, very preferably 150 to 600, most preferably 200 to 500.

[0087] Compound BThe multiple compounds may contain the compound B. The compound B is represented by formula (II);

[0088] The multiple compounds contain the compound B. This is not bound by theory, but it is considered that the compound B stabilizes a photoacid generator. It is considered that a photoacid generator decomposes under theexistence of an amine and that the compound B suppresses the photoacid generator ‘s decomposition.

[0089] The compound B is represented by formula (I);wherein R1to R5are each independently H, C1-20 alkyl, C1-20 alkoxy, OH or NH2, preferably H, linear, branched or cyclic structure containing C1-20 alkyl, linear, branched or cyclic structure containing C1-20 alkoxy or OH, more preferably H, linear, branched or cyclic structure containing C1-10 alkyl, linear, branched or cyclic structure containing C1-10 alkoxy or OH, very preferably H or OH.When R1to R5are each independently an alkyl, one or more non-adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO — 0 — , — 0 — CO — , — 0 — CO — 0 — , — CR CR — or — C = C — , preferably not replaced.

[0090] Preferably at least one of R1to R5is OH, more preferably at least one of R1and R5is OH, very preferably R1or R5is OH.Preferably at least one of R1to R5is H, more preferably at least one of R2to R4is H, very preferably R1to R4are H.

[0091] Exemplified embodiments of the compound B are selected from one or more members of the following group consisting of:

[0092] The molecular weight of the compound B is preferably in the range from 10 to 1 ,000, more preferably 30 to 800, very preferably 50 to 500, and most preferably 100 to 300. The molecular weight of the compound B can be measured by well-known methods such as freezing point depression method and vapor pressure depression method.

[0093] The content of the compound B is preferably 0.01 to 1 mass parts, more preferably 0.05 to 0.8 mass parts, very preferably 0.07 to 0.5 mass parts based on 100 mass parts of the polymer.

[0094] The molar ratio of the compound B to the amine is preferably in the range from 0.1 to 10, more preferably 0.2 to 8, very preferably 0.3 to 5 and most preferably 0.5 to 3.

[0095] This is not bound by theory, but it is considered that the compound B further sufficiently suppresses the decomposition of the photoacid generator when the molar ratio of the compound B to the amine is in the above- mentioned range.

[0096] SolventThe multiple compounds may include a solvent.The solvent may be selected from one or more members of the following group consisting of methanol, ethanol, n-propanol, i-propanol (isopropyl alcohol, IPA), n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i- pentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n- hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, heptanol-3, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6- dimethylheptanol-4, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, phenylmethylcarbinol, diacetone alcohol, cresol, ethylene glycol, propylene glycol, 1 ,3-butylene glycol, pentanediol-2,4, 2-methylpentanediol-2,4, hexanediol-2,5, heptanediol-2,4, 2-ethyl-1 ,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-n-hexyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-n-hexyl ether, ethoxytriglycol, propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono propyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, 4-methyl-2-pentanol, 3-methyl-2-pentanol, 2-methyl-2-pentanol, 3-methyl-2-butanol, 2-methyl-2- butanol, 4-methyl-2-hexanol, 5-methyl-2-hexanol, 3-methyl-2-hexanol, 2-methyl-2-hexanol, ethyl lactate (EL), propyl lactate, n-butyl lactate, n-amyl lactate, butyric acid, methyl 2-hydroxyisobutyrate, methyl 2-hydroxybutyrate, methyl 3-hydroxybutyrate, methyl 4-hydroxybutyrate, ethyl 2- hydroxyisobutyrate, ethyl 2-hydroxybutyrate, ethyl 3-hydroxybutyric acid and ethyl 4-hydroxybutyrate, preferably selected from one or more members of the following group consisting of i-propanol, PGME, PGMEA, EL, propylene glycol dimethyl ether and N-methylpyrrolidone, more preferably selected from one or more members of the following group consisting of the group consisting of PGME, PGMEA and EL.

[0097] The boiling point of the solvent at 101 ,325 Pa is preferably 30 to 300°C, more preferably 40 to 250°C, and very preferably 50 to 200°C.

[0098] The content of the solvent is preferably in the range from 500 to 3,000 mass parts, more preferably 1 ,000 to 2,000 mass parts, very preferably 700 to 1 ,700 mass parts based on 100 mass parts of the polymer.

[0099] Photobase generatorThe multiple compounds may contain a photobase generator. The photobase generator may be selected from one or more members of the following group consisting of 1 ,2-Dicyclohexyl-4,4,5,5-tetramethylbiguanidium n- butyltriphenylborate, nitrobenzyl capped 1 ,8-diazabicyclo-[5.4.0]undec-7-ene, benzyl capped 1 ,8-diazabicyclo-[5.4.0]undec-7-ene, 2-(9-Oxoxanthen-2- yl)propionic acid 1 ,5,7-triazabicyclo[4.4.0]dec-5-ene salt, 1 ,5,7- Triazabicyclo[4.4.0]dec-5-ene-HBPh4 and triphenylmethanol, preferably triphenylmethanol.

[0100] The content of the photobase generator is preferably in the range from 0.1 to 5 mass parts, more preferably 0.3 to 3 mass parts, very preferably 0.5 to 2 mass parts based on 100 mass parts of the polymer.

[0101] SurfactantThe multiple compounds may contain a surfactant. The surfactant may be a nonionic surfactant, an anionic surfactant or an amphoteric surfactant.

[0102] The nonionic surfactant may be selected from one or more members of the following group consisting of f polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene oleyl ether and polyoxyethylene cetyl ether, polyoxyethylene fatty acid diesters, polyoxyethylene fatty acid monoesters, polyoxyethylene polyoxypropylene block polymer, acetylene alcohol, acetylene glycol, polyethoxylate of acetylene alcohol, acetylene glycol derivatives such as polyethoxylate of acetylene glycol, fluorine-containing surfactants such as FLUORAD (trade name, 3M Japan), MEGAFACE (trade name: DIC), SURFLON (trade name, AGC), organosiloxane surfactants such as KF-53 (trade name, Shin-Etsu Chemical), polyether-modified siloxane and BYK-333 (trade name, BYK). Examples of the acetylene glycol include 3-methyl-1-butyne-3-ol, 3-methyl-1- pentyn-3-ol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl- 5-decyne- 4,7-diol, 3,5-dimethyl-1-hexyne-3-ol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,5- dimethyl-2,5-hexanediol.It is a preferred embodiment that the surfactant is a polyether-modified siloxane.

[0103] The content of the surfactant is in the range from 0.01 to 0.5 mass parts, more preferably 0.02 to 0.3 mass parts, very preferably 0.03 to 0.1 mass parts based on 100 mass parts of the polymer.

[0104] Other compoundsThe multiple compounds may contain a compound other than the above- mentioned compound.

[0105] The other compound may be selected from one or more members of the following group consisting of a surface smoothing agent, a dye, a contrastenhancer, an acid, a radical generator, a substrate adhesion enhancer, a plasticizer and an antifoaming agent.

[0106] The dye may be an anthracene compound. It is a preferred embodiment that the anthracene compound is 9-(4-hydroxybenzil)-1-(4- hydroxyphenyl)anthracene.

[0107] The content of the other compound is preferably in the range from 0.1 to 5 mass parts, more preferably 0.3 to 3 mass parts, very preferably 0.5 to 2 mass parts based on 100 mass parts of the polymer.

[0108] [Photoresist composition]In another aspect, the present invention also relates to the photoresist composition comprising a polymer, a photoacid generator, a compound A represented by formula (I), wherein the molar ratio of the compound A to the photoacid generator is in the range from 0.05 to 3, preferably 0.06 to 1 .5, more preferably 0.07 to 0.5.

[0109] Compound AThe photoresist composition contains the compound A. The detail of the compound is described in the section of “Compound A” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0110] Photoacid generatorThe photoresist composition contains a photoacid generator. The detail of the photoacid generator is describe in the section of “Photoacid generator” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0111] PolymerThe photoresist composition contains a polymer. The detail of the polymer is described in the section of “Polymer” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0112] AmineThe photoresist composition may contain an amine. The detail of the amine is described in the section of “Amine” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0113] Compound BThe photoresist composition may contain the compound B. The detail of the compound B is described in the section of “Compound B” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0114] SolventThe photoresist composition may contain a solvent.The detail of the solvent is described in the section of “Solvent” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0115] Photobase generatorThe photoresist composition may contain a photobase generator. The detail of the photobase generator is described in the section of “Photobase generator” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0116] SurfactantThe photoresist composition may contain a surfactant. The detail of the surfactant is described in the section of “Surfactant” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0117] Other compoundsThe photoresist composition may contain a compound other than the above- mentioned compound. The detail of the other compound is described in the section of “Other compounds” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0118] [Use of a compound A]In another aspect, the present invention further relates to use of a compound A for stabilizing a photoacid generator in a photoresist composition.The detail of the compound A is described in the section of “Compound A” in “Method for stabilizing a photoacid generator in a photoresist composition.”

[0119] [Example]The present invention is described below with reference to several examples. The embodiment of the present invention is not limited only to these examples. Mass parts of every ingredient in the examples are all based on 100 mass parts of the polymers.

[0120] Preparation of photoresist composition Example 11.156 mass parts of 2,6-Di-tert-butyl-4-methylphenol is added to 159.60 mass parts of PGME. 2.0 mass parts of bis(4- methylphenylsulfonyl)diazomethane, 0.6 mass parts of di(4-t- butyl)phenyliodonium 2-(trifluoromethyl)benzenesulfonate, and 1.5 mass parts of [4-(1 ,1-Dimethylethyl)phenyl]diphenylsulfonium perfluorobutanesulfonate and 0.232 mass parts of triphenylsulfonium 2- hydroxybenzoate (photoacid generators) are added to 150.60 mass parts of PGME separately. The PGME solution of 2,6-Di-tert-butyl-4-methylphenol and the PGME solution of the photoacid generators are mixed. To the mixed solution, 792.98 mass parts of PGMEA and 319.52 mass parts of EL are added simultaneously. To the mixed solution, 30.0 mass parts of polymer (1 ) and 70.0 mass parts of polymer (2) are added simultaneously. To the mixed solution, 0.812 mass parts of triphenylmethanol is added. To the mixed solution, 0.371 mass parts of tri-n-octylamine is added. To the mixed solution, 0.06 mass parts of polyether-modified polysiloxane and 0.84 mass parts of 9-(4-hydroxybenzil)-1-(4-hydroxyphenyl)anthracene are added simultaneously.The mixed solution is stirred overnight at 25°C and the solution is filtrated by a 0.05pm thick filter to yield the photoresist composition.[01211 Example 2Except for the point that the amount of 2,6-Di-tert-butyl-4-methylphenol is changed from 1 .156 mass parts to 0.462 mass parts, the photoresist composition is yielded by the same manner as described by example 1 .[01221 Example sExcept for the point that the amount of 2,6-Di-tert-butyl-4-methylphenol is changed from 1 .156 mass parts to 0.213 mass parts, the photoresist composition is yielded by the same manner as described by example 1 .[01231 Example 4Except for the point that 0.29 mass parts of 2-hydroxybenzoic acid is further added together with the tri-n-octylamine, the photoresist composition is yielded by the same manner as described by example 2.

[0124] Example 5Except for the point that 0.29 mass parts of 2-hydroxybenzoic acid is further added together with the tri-n-octylamine, the photoresist composition is yielded by the same manner as described by example 3.

[0125] Comparative Example 1Except for the point that the amount of 2,6-Di-tert-butyl-4-methylphenol is changed from 1.156 mass parts to 0.1156 mass parts, the photoresist composition is yielded by the same manner as described by example 1 .

[0126] Comparative Example 2Except for the point that 2,6-Di-tert-butyl-4-methylphenol is not added, the photoresist composition is yielded by the same manner as described by example 1 .

[0127] The structures of the polymers and the photoacid generators used in the Examples and the Comparative Example are the followings.Polymer (1 )Mw: 12,000, PDI: 1.84Polymer (2)Mw: 13,000, PDL1.92Bis(4-methylphenylsulfonyl)diazomethane- 38 -Di(4-t-butyl)phenyliodonium 2-(trifluoromethyl)benzenesulfonate10[4-( 1 , 1 -Dimethylethyl)phenyl]diphenylsulfonium perfluorobutanesulfonate2025T riphenylsulfonium 2-hydroxybenzoate30

[0128] The molar ratios of the compound A to the amine and the molar ratios of the compound B to the photoacid generators are shown on Table 1 .[Table 1]

[0129] Aging testThe photoresist compositions of Examples 1 to 5 and Comparative examples 1 and 2 are divided into two portions respectively and stored in brown glass bottles. One bottle is placed in a -20°C environment to serve as a reference sample. The other is subjected to an accelerated aging test by being kept in a 40°C environment for one week, simulating the effects of half a year's aging at room temperature.

[0130] CoatingThe aged photoresist compositions are coated on 8-inch wafers respectively using MK-8 clean track (Tokyo Electron). The wafers are first placed in an oven unit at 90°C for 35 seconds for Hexamethyldisilazan (HMDS) preprocessing. The spin speed is adjusted to approximately 1200 rpm to achieve a film thickness of 310 nm. Subseguently, the wafers coated with the photoresist compositions undergo a post-apply bake (PAB) process at 90°C for 35 seconds. A 43nm top antireflective coating layer (TARC AZ Aguatar- VIII A30) is applied on top of the photoresist layer at a speed of approximately 780 rpm.

[0131] Lithography before agingThe wafers are prepped for the lithography process. A KrF stepper FPS300- EX5 (Canon) is utilized for the lithography processes. The stepper's numerical aperture is 0.63, and its sigma value is 0.65. IT&DT photo mask with CD size of 180nm is chosen for lithography. The size of the mask is fixed at the above size and a plurality of resist patterns is formed by changing the exposure amount and implementing the development mentioned later. A calibration curve is prepared based on the exposure mount data. From this calibration curve, the exposure amount where the measured size of the resist pattern coincides with the mask size (a pattern of 1 :1 line and space) is determined. The determined exposure amount is referred to as Eop. The Eop values of the reference samples stored at -20°C are labeled as Eop1 , while those of the aged samples maintained at 40°C are designated as Eop2.

[0132] DevelopmentAfter the lithography, the wafers are returned to the clean track for further development. The wafers undergo a post-exposure bake (FEB) at 135°C for 90 seconds. Thereafter, it is developed using a 2.38 wt.% tetramethylammonium hydroxide developer for 30 seconds to form the photoresist patterns on the wafers respectively.

[0133] Stability AssessmentThe change rate between Eop1 and Eop2 is calculated based on the formula below.ΔEop = (Eop1 - Eop2) / Eop1 X 100 (%)The photoacid generator stability is assessed based on the following criteria.A: Δ Eop <9%B: 9%≤AEop< 15%C: ΔEop≥ 15%

[0134] The result of the assessment is shown on Table 2.[Table 2]

[0135] As shown in Table 2, Examples 1 to 5 show improved AEop values compering to the AEop value of Comparative Examples 1 and 2.

Claims

Claims1 . A method for stabilizing a photoacid generator in a photoresist composition comprising step (a);(a) mixing multiple compounds to form a photoresist composition, wherein the multiple compounds comprise a polymer, a photoacid generator, and a compound A represented by formula (I);wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy, preferably C1-20 alkyl, more preferably C1-10 alkyl;R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy, preferably H or C1-20 alkyl, more preferably H or C1-10 alkyl; when R1to R5are each independently an alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO— 0— , — 0— CO— , — 0— CO— 0— , — CR CR— or — CEC— ; wherein R3and R4may form a mono- or polycyclic organic ring system with each other.

2. The method according to claim 1 , wherein the molar ratio of the compound A to the photoacid generator is in the range from 0.05 to 3, preferably 0.06 to 1 .5, more preferably 0.07 to 0.5.

3. The method according to claims 1 or 2, wherein the multiple compounds further comprise a compound B represented by formula (II) and an amine;wherein R1to R5are each independently H, C1-20 alkyl, C1-20 alkoxy, OH or NH2, preferably H, C1-10 alkyl or OH, more preferably H or OH; when R1to R5are each independently an alkyl, one or more non-adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO — 0 — , — 0— CO— , — 0— CO— 0— , — CR CR— or — C = C— .

4. The method according to claim 3, wherein the molar ratio of the compound B to the amine is in the range from 0.1 to 10, preferably 0.2 to 8, more preferably 0.3 to 5, very preferably 0.5 to 3, preferably the content of the amine is in the range from 0.1 to 1 mass parts, more preferably 0.2 to 0.9 pass parts, very preferably 0.3 to 0.8 mass parts based on 100 parts of the polymer.

5. The method according to claims 3 or 4, wherein the amine is a tertiary amine, preferably selected from one or more members of the following group consisting of trimethylamine, triethylamine, tri-n-propylamine, tri-n- butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n- octylamine, tri-n-nonylamine, tri-n-decanylamine and tri-n-dodecylamine, more preferably selected from one or more members of the following group consisting of tri-n-heptylamine, tri-n-octylamine and tri-n-nonylamine.

6. The method according to any one of claims of 1 to 5, wherein the photoacid generator comprises a cation represented by formula (III);wherein R1to R2are each independently C1-20 alkyl, C1-20 aryl or C1-20 aralkyl, preferably C1-15 aryl or C1-15 aralkyl, more preferably C1-10 aryl.

7. The method according to any one of claims 1 to 6, wherein the multiple compounds further comprise a solvent, preferably selected from one or more members of the following group consisting of i-propanol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol dimethyl ether, ethyl lactate and N-methylpyrrolidone, more preferably selected from one or more members of the following group consisting of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and ethyl lactate.

8. A photoresist composition comprising a polymer, a photoacid generator and a compound A represented by formula (I), wherein the molar ratio of the compound A to the photoacid generator is in the range from 0.05 to 3, preferably 0.06 to 1 .5, more preferably 0.07 to 0.5;wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy, preferably C1-20 alkyl, more preferably C1-10 alkyl;R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy, preferably H or C1-20 alkyl, more preferably H or C1-10 alkyl;when R1to R5are each independently an alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO— 0— , — 0— CO— — 0— CO— 0— , — CR CR— or — C=C— ; wherein R3and R4may form a mono- or polycyclic organic ring system with each other.

9. The photoresist composition according to claim 8, wherein the composition further comprises a compound B represented by formula (II) and an amine;wherein R1to R5are each independently H, C1-20 alkyl, C1-20 alkoxy, OH or NH2, preferably H, C1-10 alkyl or OH, more preferably H or OH; when R1to R5are each independently an alkyl, one or more non-adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO — 0 — , — 0— CO— , — 0— CO— 0— , — CR CR— or — C = C— .

10. The photoresist composition according to claim 9, wherein the molar ratio of the compound B to the amine is in the range from 0.1 to 10, preferably 0.2 to 8, more preferably 0.3 to 5, very preferably 0.5 to 3, preferably the content of the amine is in the range from 0.1 to 1 mass parts, more preferably 0.2 to 0.9 pass parts, very preferably 0.3 to 0.8 mass parts based on 100 parts of the polymer.11 . The photoresist composition according to claims 9 or 10, wherein the amine is a tertiary amine, preferably selected from one or more members of the following group consisting of the group consisting of trimethylamine,triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n- pentylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n- decanylamine and tri-n-dodecylamine, more preferably selected from one or more members of the following group consisting of tri-n-heptylamine, tri-n- octylamine and tri-n-nonylamine.

12. The photoresist composition according to any one of claims 8 to 11 , wherein the photoacid generator comprises a cation represented by formula (HI);wherein R1to R2are each independently C1-20 alkyl, C1-20 aryl or C1-20 aralkyl, preferably C1-15 aryl or C1-15 aralkyl, more preferably C1-10 aryl.

13. The photoresist composition according to any one of claims 8 to 12, wherein the photoresist composition further comprises a solvent, preferably selected from one or more members of the following group consisting of i- propanol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol dimethyl ether, ethyl lactate and N- methylpyrrolidone, more preferably selected from one or more members of the following group consisting of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and ethyl lactate.

14. The photoresist composition according to any one of claims 8 to 13, wherein the polymer comprises at least one of the following repeating units (A-1 ) to (A-4);wherein R1 1, R21, R41and R45are each independently C1-10 alkyl; one or more of non-adjacent CH2-groups of R11, R21, R41and R45are optionally replaced by -O-;R12, R13, R14, R22, R23, R24, R31, R32, R33, R34, R42, R43and R44are each independently H, C1-5 alkyl, C1-5 alkoxy or -COOH; p11 is 0 to 4, p15 is 0 to 2, and p11 + p15 5; ≤ p21 is 0 to 4; n21 is 0 to 1 ; p41 is 0 to 4, p45 is 1 to 2, and p41 + p45 5. ≤15. Use of a compound A represented by formula (I) for stabilizing a photoacid generator in a photoresist composition;wherein R1and R5are each independently C1-20 alkyl or C1-20 alkoxy, preferably C1-20 alkyl, more preferably C1-10 alkyl;R2to R4are each independently H, C1-20 alkyl or C1-20 alkoxy, preferably H or C1-20 alkyl, more preferably H or C1-10 alkyl;when R1to R5are each independently an alkyl, then one or more of non- adjacent CH2-groups are optionally replaced by — 0 — , — S — , — CO — , — CO— 0— , — 0— CO— — 0— CO— 0— , — CR CR— or — C=C— ; wherein R3and R4may form a mono- or polycyclic organic ring system with each other.

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