Photosensitive resin composition, pattern forming method, and method for manufacturing electronic device

Abstract

To provide a photosensitive resin composition that includes a novolac resin and exhibits excellent resolution and heat resistance, a pattern forming method using the photosensitive resin composition, and a method for manufacturing an electronic device using the pattern forming method.SOLUTION: A photosensitive resin composition comprises an acid-degradable resin comprising a second unit, where R1 in formula (1) and R2 and R3 in formula (2) are acid-degradable groups, a photoacid generator, and a solvent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a photosensitive resin composition, a pattern forming method, and a method for manufacturing an electronic device. More specifically, the present invention relates to a photosensitive resin composition containing an acid-decomposable resin, a photoacid generator, and a solvent, a pattern forming method using the same, and a method for manufacturing an electronic device including the pattern forming method. [Background technology]

[0002] Photosensitive resin compositions are used in the process of manufacturing electronic components, for example, in etching electronic substrates, ion implantation, metal sputtering, metal plating, etc. The photosensitive resin composition is a composition containing an acid-decomposable resin, a photoacid generator, a solvent, etc., and is used for the purpose of forming a photosensitive resin film by coating and drying, and obtaining a desired fine pattern by exposing and developing the photosensitive resin film. For example, Patent Document 1 listed below discloses a photosensitive resin composition containing a novolak resin having a protecting group introduced therein, an acid generator, and a solvent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-204036 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional photosensitive resin compositions using novolak resins have room for improvement in terms of resolution and heat resistance. The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a photosensitive resin composition using a novolac resin, which is excellent in resolution and heat resistance, a pattern formation method using the same, and a method for manufacturing an electronic device including the pattern formation method. [Means for solving the problem]

[0005] That is, the present invention includes the following. [1] having units connected to each other via methylene groups, The unit includes a first unit represented by the following formula (1) and at least the second unit represented by the following formula (2): [ka] R in the above formula (1) 1 R in the formula (2) 2 R in the formula (2) 3 is at least partially an acid-decomposable group, the acid-decomposable group is selected from the group consisting of a 1-ethoxyethyl group and a 1-propoxyethyl group; an acid-decomposable resin that satisfies 0.2≦m / (n+m)≦1, where n is the number of the first units and m is the number of the second units; A photoacid generator; A photosensitive resin composition comprising: [2] The photosensitive resin composition according to the above [1], wherein the modification rate with the acid-decomposable group is 10 to 50%. [3] The photosensitive resin composition according to the above [1] or [2], wherein the photoacid generator contains a compound that generates a fluorine-containing acid upon irradiation with light. [4] The photosensitive resin composition according to any one of [1] to [3] above, wherein the solvent contains a cyclic ketone. [5] A film formation step of forming a photosensitive resin film using the photosensitive resin composition according to any one of [1] to [4] above; an exposure step of exposing the photosensitive resin film to light; a developing step of developing the photosensitive resin film. [6] A method for producing an electronic device, comprising the pattern formation method according to [5] above. Effect of the Invention

[0006] According to the present photosensitive resin composition, excellent resolution and excellent heat resistance can be achieved in a photosensitive resin composition using a novolak resin. According to this pattern forming method, it is possible to realize pattern formation using the above-mentioned photosensitive resin composition. According to the present method for producing an electronic device, it is possible to realize the production of an electronic device using the above-mentioned pattern formation method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention will be described below based on specific embodiments. However, the present invention is not limited to these embodiments. These embodiments are merely examples shown for the sake of convenience, and the present invention is not limited to these in any sense. The present invention can be modified in various ways depending on the purpose and application. In addition, all publications, patents, and patent applications cited in this specification are incorporated herein by reference as they are. In addition, in this specification, the description "XX-YY" means "XX or more and YY or less." Furthermore, in the compounds exemplified in this specification, a CAS Registry Number may be written in addition to a part of a compound name that has multiple notations, but since the CAS Registry Number differs depending on the isomeric form, etc., this is only an example of the compound name written in addition, and does not correspond one-to-one to the compound name and the CAS Registry Number.

[0008] [1] Photosensitive resin composition The photosensitive resin composition contains an acid-decomposable resin, a photoacid generator, and a solvent. Each of these components will be described in detail below.

[0009] <1> acid decomposable resin In the present invention, the acid-decomposable resin has units connected to each other via methylene groups, The unit includes a first unit represented by the following formula (1) and at least the second unit represented by the following formula (2): [ka] At least a part of R1 in the formula (1), R2 in the formula (2), and R3 in the formula (2) is an acid-decomposable group, the acid-decomposable group is selected from the group consisting of a 1-ethoxyethyl group and a 1-propoxyethyl group; When the number of the first units is n and the number of the second units is m, 0.2≦m / (n+m)≦1 is satisfied.

[0010] The acid-decomposable resin may be obtained by any method, but may be expressed as, for example, a copolymer (novolac resin) in which a phenolic compound and an aldehyde compound are monomers. That is, the first unit and the second unit are structural units derived from the phenolic compound, and the methylene group is a structural unit derived from the aldehyde compound. A phenolic compound is a compound having a phenolic hydroxy group. That is, the phenolic hydroxy group is a hydroxy group bonded to a carbon atom that constitutes an aromatic ring and has no substituent other than the hydroxy group. An aldehyde compound is a compound having an aldehyde group (-CHO).

[0011] At least a part of the first unit and the second unit has an acid-decomposable group. The acid-decomposable group is a group that is decomposed from the acid-decomposable resin in the presence of an acid. In the present invention, the acid-decomposable group includes a 1-ethoxyethyl group and a 1-propoxyethyl group.

[0012] The first unit (the unit represented by the above formula (1)) is a unit based on o-cresol. 1 " is H (hydrogen atom) or an acid-decomposable group. For example, when the acid-decomposable resin contains a plurality of first units, "R 1 " may all have the same structure or may have different structures. Furthermore, when the acid-decomposable resin contains a plurality of first units, "R 1" may be an embodiment in which only a portion thereof is an acid-decomposable group, and the other portion is H. The acid-decomposable group may be only a 1-ethoxyethyl group, only a 1-propoxyethyl group, or both a 1-ethoxyethyl group and a 1-propoxyethyl group. In the acid-decomposable resin, the first unit may also form a polymerization terminal.

[0013] The second unit (the unit represented by the above formula (2)) is a unit based on o-cresol biphenyl. o-cresol biphenyl can be said to be a compound in which two o-cresols are bonded together. In other words, o-cresol can be said to be a compound having a benzene ring and a methyl group and a hydroxy group bonded to each of two adjacent carbon atoms constituting the benzene ring. In contrast, o-cresol biphenyl can be said to be a compound in which two o-cresols are bonded together via the carbon atoms constituting each benzene ring.

[0014] Specifically, examples of o-cresol biphenyl include 3,3'-dimethylbiphenyl-4,4'-diol (CAS RN 612-84-0), 3,4'-dimethylbiphenyl-4,3'-diol, 2,2'-dimethylbiphenyl-3,3'-diol, 2,3'-dimethylbiphenyl-3,2'-diol, 4,2'-dimethylbiphenyl-3,3'-diol, 4,3'-dimethylbiphenyl-3,2'-diol, 3,3'-dimethylbiphenyl-4,2'-diol, etc. These may be used alone or in combination of two or more.

[0015] The second unit is "R 2 " and "R 3 " is H (hydrogen atom) or an acid-decomposable group. When the acid-decomposable resin contains a plurality of second units, "R 2 " may all have the same structure or may have different structures. That is, the acid-decomposable resin may have a plurality of "R 2 " If "R 2In one embodiment, only a portion of "R" is an acid-decomposable group, and the other portion is H. 2 " has a plurality of acid-decomposable groups, these acid-decomposable groups may be only 1-ethoxyethyl groups, may be only 1-propoxyethyl groups, or may be both 1-ethoxyethyl groups and 1-propoxyethyl groups. Similarly, acid-decomposable resins may contain multiple "R 3 " If "R 3 In one embodiment, only a portion of "R" is an acid-decomposable group, and the other portion is H. 3 " has a plurality of acid-decomposable groups, these acid-decomposable groups may be only 1-ethoxyethyl groups, may be only 1-propoxyethyl groups, or may be both 1-ethoxyethyl groups and 1-propoxyethyl groups. In the acid-decomposable resin, the second unit may also form a polymerization terminal.

[0016] From the above, examples of the acid-decomposable resin include polymer 《1》 represented by the following formula (3) and polymer 《2》 represented by the following formula (4). These may be used alone or in combination of two or more. That is, more specifically, the acid-decomposable resin is a resin containing at least one of polymer 《1》 and polymer 《2》.

[0017] Polymer 1: A polymer having second units connected to each other via methylene groups and no first units. [ka]

[0018] The abundance ratio of the first units and the second units in this polymer 1 is m / (n+m)=1, where n is the number of the first units and m is the number of the second units. The range of m in the formula (3) is not limited, but can be, for example, 1 to 3,000. In addition, R in formula (3) 2 and R 3At least a part of R is an acid-decomposable group, and the other part is a hydrogen atom. That is, the polymer 《1》 has a plurality of second units, and at least a part of the plurality of second units has one or two acid-decomposable groups. Therefore, the types of second units that the polymer 《1》 can have include R 2 and R 3 The second unit, R, is a hydrogen atom. 2 is a hydrogen atom and R 3 a second unit in which R is an acid-decomposable group; 2 is an acid-decomposable group, and R 3 is a hydrogen atom. These may be used alone or in combination of two or more.

[0019] The acid-decomposable group is selected from the group consisting of 1-ethoxyethyl and 1-propoxyethyl groups. Therefore, the type of the second unit having an acid-decomposable group among the second units that the polymer 1 can have is R 2 is a hydrogen atom and R 3 The second unit, R 2 is a hydrogen atom and R 3 the second unit, R 2 is a 1-ethoxyethyl group and R 3 The second unit, R 2 is a 1-ethoxyethyl group and R 3 the second unit, R 2 is a 1-propoxyethyl group and R 3 The second unit, R 2 is a 1-propoxyethyl group and R 3 and the second unit is a 1-propoxyethyl group. These may be used alone or in combination of two or more.

[0020] In addition, R in formula (3) E1 is usually a hydrogen atom. Furthermore, R in (3) E2is usually a second unit (a structure in which a hydrogen atom is bonded to the end of the second unit represented by formula (2)).

[0021] Polymer 2: A polymer having both first and second units connected to each other via a methylene group, and satisfying 0.2≦m / (n+m)<1, where n is the number of first units and m is the number of second units. [ka]

[0022] R in Equation (4) 1 ~R 3 is at least a part of which is an acid-decomposable group and the other part is a hydrogen atom. The acid-decomposable group is selected from the group consisting of a 1-ethoxyethyl group and a 1-propoxyethyl group. In addition, R in formula (4) E1 is usually a hydrogen atom. Furthermore, R in (4) E2 is usually a first unit (a structure in which a hydrogen atom is bonded to the end of a first unit represented by formula (1)) or a second unit (a structure in which a hydrogen atom is bonded to the end of a second unit represented by formula (2)).

[0023] In addition, it is convenient to express the polymer 2 as the above formula (4), but formula (4) does not mean that each unit exists as a block. That is, the first unit may exist in a block form or randomly. Of these, it is more preferable that the first unit exists randomly. The term "the first unit is present in a block form" refers to a case where there is a molecular chain region in which it is apparent that the first unit is present in greater numbers than the second unit. That is, for example, there is a case where there is a molecular chain region in which only methylene groups and the first unit are present alternately. The term "the first unit is present randomly" refers to a state in which the first unit is present evenly throughout the molecular chain. That is, there is no case where there is a molecular chain region in which it is apparent that the first unit is present in greater numbers than the second unit.

[0024] Similarly, the second units may be present in a block fashion or randomly, with the latter being more preferred. The second units being present in blocks refers to the case where there is a molecular chain region where it is apparent that there are more second units than first units. That is, for example, there is a molecular chain region where only methylene groups and second units are present alternately. The second units being present randomly refers to a state where the second units are present evenly throughout the molecular chain. That is, there is no molecular chain region where it is apparent that there are more second units than first units.

[0025] The abundance ratio of the first units to the second units in the polymer 2 is 0.2≦m / (n+m)<1, where n is the number of the first units and m is the number of the second units. The range of m in the formula (4) is not limited, but may be, for example, 1 to 3,000. In this range, the photosensitive resin composition using the novolac resin can achieve excellent resolution and excellent heat resistance. The lower limit of m / (n+m) can be set to 0.25 or more. On the other hand, the upper limit of m / (n+m) is not limited and can be set to 0.95 or 0.90. These upper and lower limits can be appropriately combined. Therefore, for example, it can be set to 0.20 to 0.95, 0.25 to 0.95, or 0.25 to 0.90.

[0026] The acid-decomposable resin may be composed of only the first unit, the second unit, and the methylene group as the structural unit, but may contain other structural units (other units) other than these. When the other structural units are contained, t / (n+m+s+t)<0.05, t / (n+m+s+t)<0.03, or t / (n+m+s+t)<0.01 can be satisfied, where n is the number of the first units, m is the number of the second units, s is the number of the methylene groups, and t is the number of the other structural units.

[0027] Examples of other structural units include structural units derived from phenolic compounds other than o-cresol and o-cresol biphenyl, and structural units derived from aldehyde compounds other than formaldehyde. These may be used alone or in combination of two or more.

[0028] Examples of the other phenolic compounds include phenol, monoalkylphenols (p-cresol, m-cresol, pt-butylphenol, etc.), dialkylphenols (xylenols such as 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, etc.), trialkylphenols (trimethylphenol, etc.), dihydroxybenzenes (catechol, resorcinol, hydroquinone, etc.), bisphenols (bisphenol A, bisphenol B, bisphenol C, bisphenol E, bisphenol F, etc.), etc. These may be used alone or in combination of two or more. The other aldehyde compounds include aliphatic aldehydes (such as butyraldehyde), aromatic aldehydes (such as benzaldehyde), etc. These may be used alone or in combination of two or more.

[0029] The acid-decomposable resin may be obtained by any method, but as described above, it can be obtained by introducing acid-decomposable groups into a copolymer of a phenolic compound and an aldehyde compound, i.e., by substituting at least some of the hydrogen atoms of the phenolic hydroxyl groups of the phenolic compound with the acid-decomposable groups. The modification rate of the acid-decomposable resin by the acid-decomposable group is not limited, but can be 10 to 50%. In this range, the photosensitive resin composition can exhibit better resolution and better heat resistance. The lower limit of the modification rate can be 12% or more, and can be 15% or more. On the other hand, the upper limit of the modification rate can be 48% or less, and can be 45% or more. These upper and lower limits can be appropriately combined. Therefore, for example, it can be 10 to 48%, 12 to 48%, 12 to 45%, or 15 to 45%. The modification rate is calculated as (N1 / N0)×100, where N0 is the total number of structural units derived from phenolic compounds and N1 is the number of structural units having an acid-decomposable group.

[0030] The ratio of the constituent units derived from a phenolic compound constituting the acid-decomposable resin to the constituent units derived from an aldehyde compound constituting the acid-decomposable resin is not limited, but can be, for example, 0.9 to 1.1.

[0031] The molecular weight of the acid-decomposable resin is not limited, but the lower limit of the weight average molecular weight is preferably 1,000 or more from the viewpoint of heat resistance. The weight average molecular weight can be 2,000 or more, 3,000 or more, 4,000 or more, 5,000 or more, or 6,000 or more. On the other hand, the upper limit of the weight average molecular weight is preferably 50,000 or less from the viewpoint of handling. The weight average molecular weight can be 40,000 or less, 35,000 or less, 30,000 or less, 25,000 or less, or 20,000 or less. These upper and lower limits can be appropriately combined with each other. Therefore, for example, it can be 1,000 to 50,000, further 2,000 to 40,000, further 3,000 to 35,000, further 4,000 to 30,000, further 5,000 to 25,000, and further 6,000 to 20,000. The weight average molecular weight can be determined by gel permeation chromatography (GPC) measurement using polystyrene as a standard substance.

[0032] The acid-decomposable resin may be obtained by any method, and a known synthesis method may be appropriately applied. Typically, the acid-decomposable resin can be obtained by synthesizing a novolac resin by addition condensation using a phenolic compound and an aldehyde compound as monomer raw materials (synthesis of novolac resin), and introducing an acid-decomposable group into the obtained novolac resin (introduction of acid-decomposable group).

[0033] The synthesis can be carried out according to a conventional method using an acid catalyst, etc. In this case, reaction conditions such as a temperature of 60 to 150° C. for 2 to 30 hours can be used. Examples of the acid catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid, etc., organic acids such as formic acid, acetic acid, oxalic acid, trichloroacetic acid, p-toluenesulfonic acid, etc., and metal salts (divalent metal salts) such as zinc acetate, zinc chloride, magnesium acetate, etc. These may be used alone or in combination of two or more kinds.

[0034] In the above synthesis, a reaction solvent can be used. Examples of the reaction solvent include ketones such as acetone and methyl ethyl ketone, alcohols such as ethanol and butanol, esters such as ethyl acetate and butyl acetate, ether alcohols such as ethoxyethyl alcohol, and ether esters such as propylene glycol monomethyl ether acetate. These may be used alone or in combination of two or more.

[0035] The introduction of the acid-decomposable group may be performed in any manner, and the method is not limited thereto, but for example, a 1-ethoxyethyl group can be introduced by reacting ethyl vinyl ether with the novolak resin having the above-mentioned phenolic hydroxy group under an acid catalyst. Similarly, a 1-propoxyethyl group can be introduced by reacting propyl vinyl ether with the above-mentioned novolak resin having the above-mentioned phenolic hydroxy group under an acid catalyst.

[0036] After the synthesis or the introduction of the acid-decomposable group, unreacted components, oligomers, impurities, etc. can be removed. For example, the acid catalyst can be removed by adding a basic compound to neutralize the acid catalyst and removing the neutralized salt by washing with water.

[0037] The photosensitive resin composition may contain two or more types of acid-decomposable resins as long as it exhibits good sensitivity and film remaining rate. When the photosensitive resin composition contains two or more types of acid-decomposable resins, (i) all of the acid-decomposable resins may be the above-mentioned resins, or (ii) some of the resins may be resins not falling under the above. However, from the viewpoint of good sensitivity and film remaining rate, it is preferable that the photosensitive resin composition of the present embodiment does not fall under the above-mentioned (ii).

[0038] The amount of the acid-decomposable resin contained in the photosensitive resin composition is not limited, but is 50 to 99 mass%, preferably 55 to 98 mass%, and more preferably 65 to 97 mass%, when the total amount of non-volatile components (components other than the solvent) is 100 mass%.

[0039] <2> Photoacid generator The photoacid generator includes a compound that generates an acid by irradiation with light. Any photoacid generator can be used, and examples of the photoacid generator include nonionic photoacid generators and ionic photoacid generators. These may be used alone or in combination of two or more.

[0040] Examples of nonionic photoacid generators include organic halides, sulfonate esters, and sulfones. These may be used alone or in combination of two or more. Among the above, examples of sulfonate esters include 2-nitrobenzyl esters, aromatic sulfonates, oxime sulfonates, N-sulfonyloxyimides, sulfonyloxyketones, and diazonaphthoquinone 4-sulfonates. These may be used alone or in combination of two or more. Examples of sulfones include disulfones, ketosulfones, and sulfonyldiazomethanes. These may be used alone or in combination of two or more.

[0041] Examples of the ionic photoacid generator include onium salts containing onium cations. Examples of the onium salts containing onium cations include diazonium salts, phosphonium salts, sulfonium salts, and iodonium salts. These may be used alone or in combination of two or more. Examples of the anions of the onium salts include sulfonate anions, sulfonylimide anions, and sulfonylmethide anions. These may be used alone or in combination of two or more.

[0042] Among the above, ionic photoacid generators are preferred, and onium salts containing an onium cation are more preferred. In addition, the photoacid generator preferably contains a compound that generates a fluorine-containing acid as an acid. By containing such a compound (a compound that generates a fluorine-containing acid), the sensitivity can be improved. An example of such a compound is a fluorinated alkyl phosphate sulfonium salt. This fluorinated alkyl phosphate sulfonium salt can be represented by the following formula (5).

[0043] [ka]

[0044] R in Equation (5) 51 , R 52 and R 53 are each independently a hydrogen atom or a monovalent substituent, and R in formula (5) f is a fluorinated alkyl group, and n in formula (5) is an integer of 1 to 6.

[0045] Examples of the monovalent substituent include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, a hydroxy group, a carboxy group, an alkoxy group, an aryloxy group, an arylthio group, etc. The number of carbon atoms constituting the monovalent substituent is not limited, but can be 1 to 10. Among these, it is preferable to have an arylthio group, and more preferably to have a phenylthio group (C6H5-S-). In the case where the phenylthio group is present, the phenylthio group is represented by R 51 , R 52 and R 53 and the others are preferably hydrogen atoms. The fluorinated alkyl group may be a perfluoroalkyl group. f The number of carbon atoms constituting the group is not limited, but may be 1-10.

[0046] The amount of the photoacid generator contained in the photosensitive resin composition is not limited, but is 0.1 to 10 mass%, preferably 0.3 to 8 mass%, and more preferably 0.5 to 6 mass%, when the total non-volatile components (components other than the solvent) is taken as 100 mass%.

[0047] <3> solvent The type of the solvent is not limited, and any solvent can be used, but typically it is an organic solvent. Examples of organic solvents include glycol ether esters, glycol ethers, esters, ketones, lactones, etc. These may be used alone or in combination of two or more. Among these, examples of glycol ether esters include ethyl cellosolve acetate, methyl cellosolve acetate, propylene glycol monomethyl ether acetate, etc. Examples of glycol ethers include propylene glycol monomethyl ether, etc. Examples of esters include ethyl lactate, butyl acetate, amyl acetate, ethyl pyruvate, etc. Examples of lactones include γ-butyrolactone, etc. Examples of ketones include acyclic ketones and cyclic ketones. Among these, examples of acyclic ketones include acetone, methyl isobutyl ketone, 2-heptanone, etc. Examples of cyclic ketones include cyclohexanone, cyclopentanone, etc. These may be used alone or in combination of two or more.

[0048] Among the above, in the present invention, it is preferable that the solvent contains a cyclic ketone, more preferably 90 mass % or more of the total amount of the solvent, further preferably 95 mass % or more of the total amount of the solvent, and particularly preferably the entire amount of the solvent is a cyclic ketone. By using a cyclic ketone as a solvent, it is possible to suppress the deterioration of the photosensitive resin composition over time during storage. More specifically, it is possible to suppress the decrease in the residual film ratio even after the photosensitive resin composition is stored for a long period of time, such as about six months or more. Furthermore, the cyclic ketone solvent is less likely to remain inside the photosensitive resin film (a film obtained by forming a photosensitive resin composition) than other solvents (such as commonly used propylene glycol monomethyl ether acetate). This makes it possible to make the alkali solubility of the entire photosensitive resin film more uniform. As a result, it is possible to improve the rectangularity and aspect ratio of the pattern. The effect of improving the rectangularity of the pattern and the aspect ratio can also be obtained when, for example, an alkyl lactate (ethyl lactate, etc.) is used as a solvent.

[0049] <4> Other Ingredients The present photosensitive resin composition may contain components other than the acid-decomposable resin, the photoacid generator, and the solvent, as long as the desired effects are achieved. Examples of other components include quenchers, anticorrosives (such as anticorrosives for the substrate), surfactants, sensitizers, dissolution inhibitors, stabilizers, antioxidants, and other additives known in the photoresist field. These may be used alone or in combination of two or more. Among the above, the quencher is a compound that has the effect of capturing the acid generated from the photoacid generator. Specific examples include amines, ammonium salts, nitrogen-containing heterocyclic compounds exhibiting basicity, etc. These may be used alone or in combination of two or more. Among the above, the amines include aliphatic amines and aromatic amines. The aliphatic amines include primary amines, secondary amines, and tertiary amines. The aliphatic amines include monoalkylamines, dialkylamines, and trialkylamines. The aromatic amines include aniline and aniline derivatives.

[0050] Among the above, examples of the aliphatic amines include hexylamine, heptylamine, octylamine, nonylamine, decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, dibutylmethylamine, methyldipentylamine, Examples of the amines include dihexylmethylamine, dicyclohexylmethylamine, diheptylmethylamine, methyldioctylamine, methyldinonylamine, didecylmethylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, ethylenediamine, tetramethylenediamine, and hexamethylenediamine. Among the above, examples of aromatic amines include naphthylamine, aniline, diisopropylaniline, methylaniline, nitroaniline, N-methylaniline, N,N-dimethylaniline, diphenylamine, 4,4'-diamino-1,2-diphenylethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, and 4,4'-diamino-3,3'-diethyldiphenylmethane.

[0051] <5> Concentration / viscosity of photosensitive resin composition The concentration of the non-volatile components (components other than the solvent) of the photosensitive resin composition is not limited, but is preferably 30 to 60% by mass, more preferably 45 to 60% by mass. Within these preferred ranges, a photosensitive resin film that is relatively thick but has a uniform thickness can be formed using a spin coater. As a result, a pattern with a high aspect ratio can be obtained. The concentration of the photosensitive resin composition may be adjusted in any way, for example, by changing the amount and type of the solvent described above.

[0052] The photosensitive resin composition of the present invention exhibits good performance in forming a relatively thick pattern. More specifically, in forming a pattern with a high aspect ratio (the aspect ratio is the value of "height / line width" of the pattern), the shape of the pattern can be easily made rectangular. In addition, the effects of a high aspect ratio and rectangular pattern shape can be more reliably obtained by appropriately selecting a solvent. For example, a high aspect ratio and rectangular pattern shape can be obtained by using the above-mentioned cyclic ketone or alkyl lactate as a solvent. That is, by increasing the concentration of the non-volatile components (components other than the solvent) of the photosensitive resin composition as described above, it becomes easier to form a thick resin film, and by patterning the thick resin film, a pattern with a high aspect ratio can be obtained.

[0053] The viscosity of the photosensitive resin composition is not limited, but is preferably 50 to 10,000 mPa·s, more preferably 300 to 10,000 mPa·s, and even more preferably 500 to 4,000 mPa·s at 25°C. Within these preferred ranges, a photosensitive resin film that is relatively thick but has a uniform thickness can be formed using a spin coater. As a result, a pattern with a high aspect ratio can be obtained. The viscosity of the photosensitive resin composition may be adjusted in any way, for example, by changing the amount and type of the solvent described above. The viscosity of the photosensitive resin composition can be measured by a rotational viscometer, a Cannon-Fenske viscometer using a capillary tube, or a tuning fork type vibration viscometer (such as an A&D device, model number SV-10).

[0054] [2] Pattern formation method The pattern formation method includes a film formation step, an exposure step, and a development step. Each of these steps will be described in detail below.

[0055] <1> Film formation process The film formation step is a step of forming a photosensitive resin film using a photosensitive resin composition, i.e., a step of laminating a photosensitive resin film on a substrate. The type of substrate is not limited, and examples thereof include various wafers (Si wafers, SiC wafers, GaN wafers, etc.), glass substrates, ceramic substrates, metal substrates (aluminum substrates, copper substrates, etc.), plated substrates (copper plated substrates), etc. These may be used alone or in combination of two or more. These substrates may be unprocessed substrates or substrates on which electrodes, elements, etc. are formed on the surface.

[0056] The method for forming the photosensitive resin film is not limited, and a known forming method used in the field of electronic device manufacturing can be appropriately applied. That is, for example, spin coating using a spinner, spray coating using a spray coater, dip coating, printing (inkjet method, etc.), coating by roll coating, etc. can be mentioned. These can be used alone or in combination of two or more.

[0057] In addition, the photosensitive resin composition applied on the substrate is usually turned into a photosensitive resin film by removing the solvent contained therein, so the film formation step can include a solvent removal step. The method for removing the solvent is not limited, but can be performed, for example, by heat treatment. The heating temperature in the heat treatment is not limited, but is, for example, 80 to 140°C, preferably 90 to 120°C. In addition, the heating time is not limited and can be appropriately set depending on the heating device used, but for example, when a hot plate is used, it can be 30 to 300 seconds, preferably 60 to 180 seconds. In addition, when a hot air oven is used, it can be 5 to 60 minutes, preferably 10 to 30 minutes.

[0058] The thickness of the photosensitive resin film to be formed is not limited and can be adjusted appropriately depending on the application to be applied, the pattern to be finally obtained, etc. For example, when the purpose is to form copper bumps, the thickness can be 5 to 100 μm, preferably 10 to 100 μm, and more preferably 15 to 100 μm. This thickness can be adjusted by adjusting the concentration of the non-volatile components described above, selecting the coating method, etc.

[0059] The exposure step is a step of exposing the photosensitive resin film to light, which can be performed by applying actinic rays to the photosensitive resin film through a suitable photomask. Examples of actinic rays include X-rays, electron beams, ultraviolet rays, and visible rays. In terms of wavelength, light of 200 to 500 nm is preferred. In terms of pattern resolution and ease of handling, the light source is preferably g-ray, h-ray, or i-ray from a mercury lamp, and particularly preferably i-ray. Only one type of light may be used, or two or more types of light may be used in combination. The exposure step can be carried out using an exposure device. Examples of the exposure device include a contact aligner, a mirror projection, a stepper, etc. These devices may be used alone or in combination of two or more. The amount of light exposure in the exposure process is not limited, but is preferably 100 to 500 mJ / cm 2 The amount of exposure can be appropriately adjusted depending on the amount of the photosensitizer in the photosensitive resin film.

[0060] The development step is a step of developing the photosensitive resin film, that is, a step of developing the exposed photosensitive resin film with a developer to obtain a desired pattern. The development may be carried out by any method, such as a dipping method, a paddle method, a rotary spray method, etc. These may be used alone or in combination of two or more. By development, for example, the exposed portion of the photosensitive resin film is dissolved and removed, and a positive pattern can be obtained.

[0061] The type of developer is not limited, but an alkaline liquid is usually used. Examples of the developer include an inorganic alkaline aqueous solution, an organic amine aqueous solution, and a quaternary ammonium salt aqueous solution. These may be used alone or in combination of two or more. Among these, examples of solutes of inorganic alkaline aqueous solutions include sodium hydroxide, sodium carbonate, sodium silicate, ammonia, etc. Examples of solutes of organic amine aqueous solutions include ethylamine, diethylamine, triethylamine, triethanolamine, etc. Examples of solutes of quaternary ammonium salt aqueous solutions include tetramethylammonium hydroxide, tetrabutylammonium hydroxide, etc. These may be used alone or in combination of two or more. Among the above, the developer is preferably an aqueous solution of tetramethylammonium hydroxide. The concentration of tetramethylammonium hydroxide in this aqueous solution is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass.

[0062] The pattern forming method of the present invention may include other steps in addition to the film forming step, the exposure step, and the development step. Examples of the other steps include a heating step for heating the photosensitive resin film, a rinsing step, etc. These steps may be used alone or in combination of two or more.

[0063] Among the above, the heating step is a step of heating the photosensitive resin film after the exposure step and before the development step (post exposure bake). The heating temperature in the heating step is not limited, but is preferably 70 to 150°C, more preferably 70 to 120°C. In addition, the heating time in the heating step is preferably 30 to 300 seconds, more preferably 60 to 180 seconds, for example, when a hot plate is used. By providing a heating step, that is, by performing post-exposure baking, the deprotection reaction can be promoted, and further high sensitivity can be achieved. On the other hand, since 1-ethoxyethyl group and 1-propoxyethyl group as acid decomposable groups are groups that are easily deprotected, sufficient deprotection is possible without providing a heating step after exposure. In other words, high sensitivity can be obtained without post-exposure baking. This leads to a reduction in the number of steps and the number of devices, and functions as a factor for improving production efficiency.

[0064] Among the above, the rinsing step is a step of cleaning the pattern and / or the substrate with a rinsing liquid after the developing step. Ultrapure water can be suitably used as the rinsing liquid.

[0065] [3] Manufacturing methods for electronic devices The present method for manufacturing an electronic device includes the above-mentioned pattern forming method. Specifically, an electronic device can be manufactured by using a pattern obtained by the above-mentioned pattern forming method as a mask. Examples of the mask include a mask for dry etching, a mask for ion implantation process, a mask for metal sputtering, a mask for metal plating, etc. These may be used alone or in combination of two or more kinds. That is, the method for manufacturing the electronic device can include a dry etching step, an ion implantation process step, a metal sputtering step, a metal plating step, etc., using the pattern obtained by the above-mentioned pattern formation method as a mask. These steps may be used alone or in combination of two or more.

[0066] Examples of the electronic device include a semiconductor chip, a semiconductor element, a printed wiring board, an electric circuit display device, an information and communication terminal, a light-emitting diode, a physical battery, a chemical battery, etc. In other words, the electronic device includes an element, a device, a final product, etc. to which electronic engineering technology is applied. EXAMPLES

[0067] The present invention will now be described in more detail with reference to examples.

[0068] [1] Preparation of photosensitive resin composition (1) Acid-decomposable resin The following seven types of acid-decomposable resins A to G were prepared. Table 1 shows the details of the unit composition of the acid-decomposable resin (type, amount ratio, and form of each unit), the details of the acid-decomposable group (type, modification rate), and the weight average molecular weight of the acid-decomposable resin. In addition, the "form" is described as "single" when only one of the acid-decomposable resins A to G is used, and "mixed" when two or more types of acid-decomposable resins are mixed. In addition, the mixing ratio is shown for the "mixed" form.

[0069] The modification rate of the acid-decomposable group was measured using a nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., model number "JNM-ECZ400S") 13 Measured by C-NMR (observed nuclei: 13 C, solvent: dimethylsulfoxide-d6, standard substance: tetramethylsilane, number of integrations: 10240). Specifically, it was calculated as the ratio of the integral value of the peaks (156 to 148 ppm) attributable to the hydroxyl groups of the acid-decomposable resin or aromatic carbons to which acid-dissociable groups are bonded to the integral value of the peaks attributable to the acid-decomposable groups (propoxyethyl: 105 to 98 ppm, ethoxyethyl: 105 to 98 ppm).

[0070] Among the above, the weight average molecular weight (Mw) of the acid-decomposable resin is a value measured under the following conditions using a high-speed GPC device (manufactured by Tosoh Corporation, model number "HCL-8320GPC") and a column compatible with the high-speed GPC device (manufactured by Tosoh Corporation, product names "TSKGel G2000HXL, G4000HXL"), and converted using a calibration curve of standard polystyrene (manufactured by Tosoh Corporation, product names "F-40, F-20, F-10, F-4, F-2, F-1, A5000, A2500, A1000", manufactured by Tokyo Chemical Industry Co., Ltd., product name "2,2-methylenebis(4-methylphenol)", and manufactured by Kanto Chemical Co., Ltd., product name "p-cresol"). Solvent: Tetrahydrofuran (THF) Measurement temperature: 40℃ Flow rate: 1mL / min Sample concentration: Example: 3 mg / THF 5 mL, Comparative Example: 30 mg / THF 5 mL Injection volume: 100μL

[0071] Acid-decomposable resin A: A polymer in which a 1-propoxyethyl group is introduced as an acid-decomposable group into an addition condensation product of o-cresol biphenyl and formaldehyde (polymer represented by formula (3), m / (n+m)=1). Weight average molecular weight: 11921, modification rate of acid-decomposable group: 42%

[0072] Acid-decomposable resin B: A polymer in which 1-propoxyethyl groups have been introduced as acid-decomposable groups into addition condensates of o-cresol and o-cresol biphenyl with formaldehyde (polymer represented by formula (4), m / (n+m)=0.3). Weight average molecular weight: 8003, modification rate of acid-decomposable groups: 22%.

[0073] Acid-decomposable resin C: A polymer in which 1-propoxyethyl groups have been introduced as acid-decomposable groups into addition condensates of o-cresol and o-cresol biphenyl with formaldehyde (polymer represented by formula (4), m / (n+m)=0.2). Weight average molecular weight: 6176, modification rate of acid-decomposable groups: 25%.

[0074] Acid-decomposable resin D: A polymer in which 1-ethoxyethyl groups have been introduced as acid-decomposable groups into addition condensates of o-cresol and o-cresol biphenyl with formaldehyde (polymer represented by formula (4), m / (n+m)=0.2). Weight average molecular weight: 6176, modification rate of acid-decomposable groups: 25%

[0075] Acid-decomposable resin E: a resin obtained by mixing the above-mentioned Acid-decomposable resin 1 and the below-mentioned Acid-decomposable resin 6 in a mass ratio of 3:7.

[0076] Acid-decomposable resin F: A polymer in which 1-propoxyethyl groups have been introduced as acid-decomposable groups into an addition condensation product of o-cresol and formaldehyde. Weight average molecular weight: 4740, modification rate of acid-decomposable groups: 18%

[0077] Acid-decomposable resin G: A polymer in which 1-propoxyethyl groups have been introduced as acid-decomposable groups into addition condensates of o-cresol and o-cresol biphenyl with formaldehyde (polymer represented by formula (4), m / (n+m)=0.1). Weight average molecular weight: 5458, modification rate of acid-decomposable groups: 20%.

[0078] [Table 1]

[0079] In a room under yellow light, each of the acid-decomposable resins A to G shown in (1) above and each of the components shown in (2) to (4) below were mixed in the amount ratios shown in Table 2, and stirred at room temperature for 3 hours to obtain a solution. The resulting solution was filtered under nitrogen pressure using a polypropylene membrane capsule filter with a pore size of 1.0 μm, and the photosensitive resin compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were obtained as the filtrate. The composition of each component is shown in Table 2.

[0080] (2) Photoacid generator The following photoacid generators were prepared. Photoacid generator: San-Apro Co., Ltd., fluorinated alkyl phosphate sulfonium salt (diphenyl[4-(phenylsulfanyl)phenyl]sulfonium = trifluoride tris(pentafluoroethane-1-ido)phosphate), product name "CPI-210S"

[0081] (3) Solvent The following solvents were prepared: Solvent: Cyclopentanone

[0082] (4) Quencher The following quenchers were prepared: Quencher: Triethylamine (TEA)

[0083] [Table 2]

[0084] [2] Evaluation of photosensitive resin composition (1)Pattern formation The photosensitive resin compositions of Examples 1 to 5 and Comparative Examples 1 and 2 obtained in [1] above were each dropped onto a 4-inch silicon wafer, coated using a spin coater, and then prebaked on a hot plate at 100°C for 120 seconds. The thickness of the photosensitive resin film after prebaking was measured using an optical film thickness meter (manufactured by FILMMETRICS, model "F-20"). With a target film thickness of 4 um, coating and baking were repeated several times while adjusting the spin speed to obtain a photosensitive resin film with a film thickness of 4 um ± 0.1 um (film formation process). Thereafter, exposure was performed through a mask containing test patterns of various line widths with a line and space width ratio of 1:1 using an exposure device (manufactured by Mikasa Co., Ltd., model "Mask Aligner MA-20") with an ultra-high pressure mercury lamp (mixed wavelength of g-line, h-line, and i-line) as the light source (exposure process). After exposure, the film was developed by immersing in a 2.38% aqueous solution of tetramethylammonium hydroxide (developing step). After development, the film was washed with ultrapure water (rinsing step) to obtain a resist pattern. Additionally, no post-exposure bake (PEB) step was performed.

[0085] (2) Sensitivity assessment In the exposure process for forming the pattern in (1) above, the wafer was masked so that only a portion of it was exposed, and the exposure amount was repeatedly changed while appropriately shifting the non-exposed portion. 2 In steps of 100 to 300 mJ / cm 2 Thus, exposed wafers were obtained in which the exposure dose was increased stepwise. The obtained wafer was subjected to a developing process and a rinsing process, and the obtained pattern was observed under an optical microscope to determine whether the space portion of the 4 um line & space of the mask was properly opened (developed) and whether the underlying Si wafer was visible at the minimum exposure dose (10 mJ / cm 2 The minimum exposure was assigned to three levels: "high", "medium", and "low" as shown below. These assignments are shown in the "Sensitivity" column of Table 3, and the minimum exposure described above is listed as "Actual value (mJ / cm 2 ) column.

[0086] High: Sensitivity 100mJ / cm2 below Medium: Sensitivity 150mJ / cm 2 More than 250mJ / cm 2 below Low: Sensitivity 300mJ / cm 2 End

[0087] (3) Evaluation of remaining film rate The film thickness of the unexposed part of the pattern after the development and rinsing steps in (2) above was measured, and the value divided by the initial film thickness (4 um) was converted into a percentage. The obtained percentage values ​​were assigned to the three levels shown below: "High", "Medium", and "Low". These assignments are shown in the "Residual Film Ratio" column of Table 3, and the above-mentioned percentage values ​​are shown in the "Actual Value (%)" column.

[0088] High: 96% or higher Medium: 90% or more, less than 96% Low: Less than 90%

[0089] (4) Evaluation of pattern profile The area where the exposure amount is one step higher than the minimum exposure amount in the pattern after the development and rinsing steps in (2) above (+10 mJ / cm 2 The cross-sectional shape of the 4um line resist at 300nm was observed using an electron microscope (SEM image) and evaluated in three aspects, namely "verticality," "overhang," and "jaggedness," according to the criteria shown below. The evaluation results are shown in the "Pattern Profile" column of Table 3. The reason for observing the location where the exposure amount is one step larger than the minimum exposure amount is as follows. That is, at the minimum exposure amount observed with an optical microscope, the bottom part of the resist pattern is usually not completely removed, and the resist line width is often slightly larger than the mask line width. Therefore, it is reasonable to consider the optimal exposure amount to be about 1.1 to 2.0 times the minimum exposure amount, so the observation location of this profile was set to the exposure amount one step larger, that is, the point of the optimal exposure amount.

[0090] Verticality: The verticality of the rising edge in the cross section of the line resist was evaluated. That is, a profile with high verticality of the rising edge, excellent rectangularity, and suitable for the manufacturing process of electronic devices was evaluated as "vertical," and other profiles were evaluated as "non-vertical." Overhang: The presence or absence of overhangs (protrusions) at both ends of the upper end of the line resist cross section was evaluated. In other words, a cross-sectional shape in which both ends of the upper end protrude like overhangs (also called a T-top shape) was clearly observed was rated as "present", a slight overhang was observed but was rated as "slightly present", and no overhang was observed at all was rated as "absent". It is preferable that overhangs do not appear in the manufacturing process of electronic devices. Jagged edges: When the eaves were rated as "present" or "slightly present," those with saw-like jagged edges were rated as "present," and those without were rated as "absent." Note that it is preferable that jagged edges do not appear during the manufacturing process of electronic devices.

[0091] (5) Resolution evaluation In the SEM image used in (4) above, we observed areas even narrower than the 4um line and space mentioned above, and evaluated the minimum line width (um) at which the space was open, and the results are shown in the "Resolution" column in Table 2. The mask used is one that has a line and space pattern down to a minimum of 1um, with 1um step increments below 10um.

[0092] (6) Aspect ratio evaluation The aspect ratio was calculated by dividing the initial film thickness (4 um) by the minimum line width (um) obtained in (5) above, and this value is shown in the "Aspect Ratio" column in Table 3. Note that the aspect ratio, like the resolution, is an index for judging the quality of the resist performance. The aspect ratio is the ratio of the height (film thickness) of the resist profile to the line width.

[0093] (7) Heat resistance evaluation The developed wafer on which the resist pattern was formed in (1) above was heated on a hot plate heated to 120°C for 3 minutes, and the change in the resist pattern before and after heating was evaluated using SEM images, and the results are shown in the "Heat resistance" column in Table 3. That is, a resist pattern that maintained the same shape after heating as before heating was evaluated as "good," and a resist pattern that showed sagging was evaluated as "poor."

[0094] [Table 3]

[0095] From the results in Table 3, when patterns were formed using a photosensitive resin composition containing an acid-decomposable resin where "m / (n+m)=1" (Example 1, Example 5), a photosensitive resin composition containing an acid-decomposable resin where "m / (n+m)=0.3" (Example 2), and a photosensitive resin composition containing an acid-decomposable resin where "m / (n+m)=0.2" (Example 3, Example 4), excellent heat resistance was obtained. In addition, excellent results were obtained with respect to both sensitivity and residual film rate.

[0096] On the other hand, when patterns were formed using a photosensitive resin composition containing an acid-decomposable resin that does not have a structural unit derived from o-cresol biphenyl, i.e., an acid-decomposable resin that does not have a second unit (Comparative Example 1), and a photosensitive resin composition containing only an acid-decomposable resin in which "m / (n+m)=0.1" (Comparative Example 2), the heat resistance was poor.

[0097] In the photosensitive resin compositions of Examples 1 to 5, sufficiently high sensitivity was obtained without post-exposure heating. This is believed to be due to the high alkali solubility of o-cresol biphenyl. This characteristic of "sufficiently high sensitivity is obtained without post-exposure heating" is very favorable in terms of production efficiency, such as reducing the number of devices and shortening the tact time.

Claims

1. having units connected to each other via methylene groups, The unit includes a first unit represented by the following formula (1) and at least the second unit represented by the following formula (2): [Formula 1] R in the formula (1) １ , R in the formula (2) ２ , R in the formula (2) ３ is at least partially an acid-decomposable group, the acid-decomposable group is selected from the group consisting of a 1-ethoxyethyl group and a 1-propoxyethyl group; an acid-decomposable resin that satisfies 0.2≦m / (n+m)≦1, where n is the number of the first units and m is the number of the second units; A photoacid generator; A photosensitive resin composition comprising:

2. 2. The photosensitive resin composition according to claim 1, wherein the modification rate with the acid-decomposable group is 10 to 50%.

3. The photosensitive resin composition according to claim 1 , wherein the photoacid generator comprises a compound that generates a fluorine-containing acid upon irradiation with light.

4. The photosensitive resin composition according to claim 1 , wherein the solvent comprises a cyclic ketone.

5. A film forming step of forming a photosensitive resin film using the photosensitive resin composition according to any one of claims 1 to 4; an exposure step of exposing the photosensitive resin film to light; a developing step of developing the photosensitive resin film.

6. A method for manufacturing an electronic device, comprising the pattern forming method according to claim 5 .

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