Negative photosensitive resin composition and dry film resist

Abstract

To provide a dry film resist and a negative photosensitive resin composition, wherein the pre-exposure resist layer has solubility in alkaline solutions, outstanding film formation capabilities, and strong adherence, while the post-exposure cured resist demonstrates exceptional resistance to chemicals.SOLUTION: A negative photosensitive resin composition comprises the following components (A)-(C): (A) a novolac phenolic resin with the molar proportions of a structural unit (a1) derived from m-cresol, a structural unit (a2) derived from benzaldehyde, and a structural unit (a3) derived from salicylaldehyde [(a1): (a2): (a3)] being 1.0: 0.3-0.8: 0.3-0.8, (B) a radical-polymerizable compound and (C) a photopolymerization initiator.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a negative photosensitive resin composition and a dry film resist. [Background technology]

[0002] In recent years, the miniaturization of electronic devices has led to an increase in the density of semiconductor packages. In the semiconductor package manufacturing process, a resist film is formed using a resist material on a support such as a film, sheet, metal substrate, or ceramic substrate. However, as circuits become finer due to increased density, the steps on the support surface are also becoming finer. When a liquid resist material is applied to such a support surface with steps, it is difficult to obtain a resist film with a uniform thickness, and defects such as voids occur near the steps. Therefore, negative-type photosensitive dry film resists have attracted attention as a way to produce resist films with a uniform thickness and no defects near the steps.

[0003] Conventionally, negative photosensitive dry film resists have mainly been solvent-developable, using organic solvents. However, solvent development causes the resist resin to swell due to solvent absorption during development, making it unsuitable for drawing fine patterns. Therefore, instead of solvent development, fine pattern writing using an alkali-developable negative photosensitive dry film resist incorporating an alkali-soluble component has been investigated (for example, Patent Document 1). However, in the pattern formation of Patent Document 1, because the alkali-soluble component uses a parahydroxystyrene skeleton or a functional group such as a carboxyl group, it is difficult to control the alkali dissolution rate, and post-development residues are left in the exposed areas and film loss occurs in the unexposed areas, making it difficult to form fine patterns of 10 or so μm or less, and also the chemical resistance is insufficient.

[0004] Therefore, the development of negative dry film resists containing phenol novolac resins to control the alkaline dissolution rate has been investigated (for example, Patent Document 2). However, in the pattern formation of Patent Document 2, the alkaline development rate of the phenol novolac resin is insufficient, so the problem of post-development residues in exposed areas remains unresolved. In addition, it is difficult to draw fine patterns of 10 or so micrometers or less, and there are problems with film formation defects when forming a resist film on a film and adhesion to the support inside a semiconductor package.

[0005] As described above, with the increasing density of semiconductor packages, there is a demand for the development of a negative photosensitive dry film resist that can draw finer patterns without generating residues, can form a coating film on a substrate film without film formation defects, and has solvent resistance and substrate adhesion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-151489 [Patent Document 2] Japanese Patent Application Publication No. 2019-128438 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a dry film resist and a negative photosensitive resin composition in which the resist layer before exposure has alkali solubility, is excellent in film formability and adhesion, and the cured resist after exposure has excellent chemical resistance. [Means for solving the problem]

[0008] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that by using a negative photosensitive resin composition that combines a novolac-type phenolic resin composition having a specific structural unit, a radically polymerizable compound, and a photopolymerization initiator, it is possible to obtain a dry film resist that can improve the alkaline solubility of a resist layer before exposure, has excellent film-forming properties and adhesion, and provides a cured resist with excellent chemical resistance, and have completed the present invention.

[0009] That is, the present invention relates to a negative photosensitive resin composition containing the following components (A) to (C): (A) A novolac phenolic resin in which the molar ratio of the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde [(a1):(a2):(a3)] is 1.0:0.3-0.8:0.3-0.8. (B) Radical polymerizable compound (C) Photopolymerization initiator

[0010] The present invention further relates to a dry film resist comprising a substrate film and a resist layer containing the negative photosensitive resin composition. The present invention further relates to a cured product of the resist layer. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a dry film resist and a negative photosensitive resin composition in which the resist layer before exposure has alkali solubility, has excellent film-forming properties and adhesion, and the cured resist has excellent chemical resistance. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a GPC chart of the novolac phenolic resin obtained in Synthesis Example 1. [Figure 2] 1 is a GPC chart of the novolak phenolic resin obtained in Synthesis Example 2. [Figure 3]1 is a GPC chart of the novolak phenolic resin obtained in Synthesis Example 3. [Figure 4] 1 is a GPC chart of the novolak phenolic resin obtained in Synthesis Example 4. [Figure 5] 1 is a GPC chart of the novolak phenolic resin obtained in Synthesis Example 5. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes the embodiments of the present invention. In this specification, "x to y" represents a numerical range of "not less than x and not more than y." The upper and lower limits of the numerical ranges can be combined in any way. Furthermore, a combination of two or more of the individual aspects of the present invention described below is also an aspect of the present invention.

[0014] [Negative-type photosensitive resin composition] A negative photosensitive resin composition according to one embodiment of the present invention contains the following components (A) to (C). (A) A novolac phenolic resin in which the molar ratio of the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde [(a1):(a2):(a3)] is 1.0:0.3-0.8:0.3-0.8. (B) Radical polymerizable compound (C) Photopolymerization initiator

[0015] In this embodiment, the use of the novolac phenolic resin (A) can prevent film formation defects on the substrate film. Furthermore, the alkali solubility of the unexposed areas is high, resulting in a resist with excellent adhesion. Furthermore, the chemical resistance of the cured resist is improved. The components of the negative photosensitive resin composition will be described below.

[0016] Ingredient (A) The novolac phenolic resin, which is component (A), has a molar ratio of the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde [(a1):(a2):(a3)] of 1.0:0.3-0.8:0.3-0.8.

[0017] The molar ratio of the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde contained in component (A) [(a1):(a2):(a3)] is preferably 1.0:0.5-0.7:0.3-0.5, and more preferably 1.0:0.55-0.65:0.35-0.45, from the viewpoint of obtaining a cured film that not only has high sensitivity but also has chemical resistance when cured at low temperature.

[0018] Component (A) may contain structural units other than the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde. Examples of structural units other than (a1) to (a3) ​​include structural units derived from phenols or aldehydes other than m-cresol, benzaldehyde, and salicylaldehyde.

[0019] Examples of the phenols include phenol, o-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, and 3,4,5-trimethylphenol.

[0020] Examples of the aldehydes include formalin, paraformaldehyde, acetaldehyde, chloroacetaldehyde, 4-hydroxybenzaldehyde, and 3-hydroxybenzaldehyde.

[0021] The total content of the structural units (a1), (a2), and (a3) ​​in component (A) is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 90% by mass or more, from the viewpoint of obtaining a cured film that not only has high sensitivity but also has chemical resistance when cured at low temperature. The total content of the structural units (a1), (a2), and (a3) ​​may be substantially 100% by mass, which means that structural units other than the structural units (a1), (a2), and (a3) ​​are inevitably contained.

[0022] The weight-average molecular weight of the novolac phenolic resin, component (A), is preferably 1,000 or more, more preferably 1,500 or more. It is also preferably 7,000 or less, more preferably 6,000 or less, and even more preferably 5,000 or less. A weight-average molecular weight of 1,000 or more is preferred because it provides high heat resistance. On the other hand, a weight-average molecular weight of 7,000 or less is preferred because it provides high sensitivity. In this specification, the weight-average molecular weight is measured according to the conditions described in the Examples.

[0023] Component (A) is obtained by polycondensing m-cresol, benzaldehyde, and salicylaldehyde in an organic solvent using an acid catalyst in a molar ratio (m-cresol:benzaldehyde:salicylaldehyde) of 1.0:0.3-0.8:0.3-0.8.

[0024] The molar ratio of m-cresol, benzaldehyde, and salicylaldehyde in the reaction solvent (m-cresol:benzaldehyde:salicylaldehyde) is preferably in the range of 1.0:0.5-0.7:0.3-0.5, more preferably 1.0:0.55-0.65:0.35-0.45, from the viewpoint of obtaining a cured film that not only has high sensitivity but also has chemical resistance when cured at low temperature.

[0025] Salicylic aldehyde The molar ratio of benzaldehyde That is, the molar ratio is preferably smaller than Salicylic aldehyde < benzaldehyde It is preferable that the molar ratio satisfies the following.

[0026] When m-cresol, benzaldehyde, and salicylaldehyde are polycondensed in an organic solvent to obtain the novolak phenolic resin that is component (A), as described above, the organic solvent may contain phenols and aldehydes other than m-cresol, benzaldehyde, and salicylaldehyde.

[0027] The proportion of the total mass of m-cresol, benzaldehyde, and salicylaldehyde in the reaction solvent relative to the total mass of all starting materials that can become structural units constituting component (A) is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably substantially 100% by mass, from the viewpoint of obtaining a cured film that not only has high sensitivity but also has chemical resistance when cured at low temperature.

[0028] Examples of reaction solvents used in producing component (A) include methanol, ethanol, 1-propanol, 2-propanol, butanol, hexanol, ethylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, methyl ethyl ketone, methyl isobutyl ketone, and toluene. Among these, one or more selected from ethanol, 1-propanol, and 2-propanol are preferred, and ethanol is more preferred.

[0029] From the viewpoint of uniformity of the reaction, the amount of the reaction solvent used is preferably 20 parts by mass or more, more preferably 50 parts by mass or more, per 100 parts by mass of the raw materials from which the structural units constituting component (A) are derived, and is preferably 500 parts by mass or less, more preferably 300 parts by mass or less.

[0030] Examples of the acid catalyst used in producing component (A) include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and boric acid, and organic acids such as oxalic acid, acetic acid, and paratoluenesulfonic acid. Among these, inorganic acids and paratoluenesulfonic acid are preferred, and paratoluenesulfonic acid is more preferred, in order to further promote the reaction. The amount of acid catalyst added is not particularly limited, but is preferably at least 5 parts by mass, more preferably at least 20 parts by mass, per 100 parts by mass of the raw materials from which the structural units constituting component (A) are derived, and is preferably at most 150 parts by mass, more preferably at most 100 parts by mass.

[0031] The reaction temperature during polycondensation of the raw materials for component (A) is preferably 30°C or higher, more preferably 40°C or higher, in order to promote the reaction and efficiently increase the molecular weight, and is preferably 100°C or lower, more preferably 80°C or lower. The reaction time is preferably 4 hours or more, more preferably 12 hours or more, and is preferably 32 hours or less, more preferably 24 hours or less.

[0032] ·Component (B) The radically polymerizable compound (component (B)) is a compound containing multiple ethylenically unsaturated groups in the molecule. The inclusion of a radically polymerizable compound accelerates the curing of the exposed area, improving sensitivity during exposure. Additionally, the crosslink density after thermal curing is improved, improving the hardness of the resist.

[0033] The radically polymerizable compound is preferably a compound having a (meth)acrylic group, which easily undergoes radical polymerization. From the viewpoint of improving sensitivity during exposure and hardness of the cured film, a compound having two or more (meth)acrylic groups in the molecule is more preferred.

[0034] Examples of the radical polymerizable compound include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ditri ... Dimethylolpropane tetra(meth)acrylate, 1,3-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, ethoxylated glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate (Meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol nona(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, pentaerythritol undeca(meth)acrylate acrylate, pentaerythritol dodeca(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, 2,2-bis[4-(3-(meth)acryloxy-2-hydroxypropoxy)phenyl]propane, 1,3,5-tris((meth)acryloxyethyl)isocyanuric acid, 1,3-bis((meth)acryloxyethyl)isocyanuric acid, 9,9-bis[4-(2-(meth)acryloxyethoxy)phenyl]fluorene, 9,9-bis[4-(3-(meth)acryloxypropoxy)phenyl]fluorene or 9,9-bis(4-(meth)acryloxyphenyl)fluorene or an acid-modified product thereof, an ethylene oxide-modified product thereof, or a propylene oxide-modified product thereof.

[0035] In one embodiment, the negative-type photosensitive resin composition does not contain, as the radical polymerizable compound, one or more resins or compounds selected from an ethylenically unsaturated group-containing polyimide, an ethylenically unsaturated group-containing polyimide precursor, an ethylenically unsaturated group-containing polybenzoxazole, and an ethylenically unsaturated group-containing polybenzoxazole precursor. In one embodiment, the negative photosensitive resin composition is for use in a dry film resist.

[0036] The amount of the radical polymerizable compound is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 5 parts by mass or more, per 100 parts by mass of component (A). A content within the above range can improve sensitivity during exposure. Meanwhile, the content of the radical polymerizable compound is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less.

[0037] ·Component (C) The photopolymerization initiator, component (C), is a compound that generates radicals through bond cleavage and / or reaction upon exposure. By incorporating a photopolymerization initiator, the exposed areas of the negative photosensitive resin composition film become insoluble in alkaline developer, allowing the formation of a negative pattern. Furthermore, curing of the exposed areas is accelerated, improving sensitivity.

[0038] The photopolymerization initiator is not particularly limited, and known photopolymerization initiators can be used. Examples of the photopolymerization initiator include benzyl ketal-based photopolymerization initiators, α-hydroxyketone-based photopolymerization initiators, α-aminoketone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, oxime ester-based photopolymerization initiators, acridine-based photopolymerization initiators, titanocene-based photopolymerization initiators, benzophenone-based photopolymerization initiators, acetophenone-based photopolymerization initiators, aromatic ketoester-based photopolymerization initiators or benzoic acid ester-based photopolymerization initiators, and α-aminoalkylphenone-based photopolymerization initiators.

[0039] The photopolymerization initiator may be used alone or in combination of two or more kinds. The amount of the photopolymerization initiator to be blended is preferably 0.1 parts by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of component (A), since this provides good sensitivity and the desired pattern, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less.

[0040] ·solvent In this embodiment, a solvent may be used in addition to the above-mentioned components (A) to (C). Examples of the solvent include polar aprotic solvents such as N-methyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, propylene glycol monomethyl ether, and propylene glycol monoethyl ether, ketones such as acetone, methyl ethyl ketone, and diisobutyl ketone, esters such as ethyl acetate, butyl acetate, isobutyl acetate, propyl acetate, propylene glycol monomethyl ether acetate, and 3-methyl-3-methoxybutyl acetate, alcohols such as ethyl lactate, methyl lactate, diacetone alcohol, and 3-methyl-3-methoxybutanol, and aromatic hydrocarbons such as toluene and xylene. These solvents may be used alone or in combination of two or more.

[0041] The amount of solvent blended in the negative photosensitive resin composition of this embodiment is such that the solids concentration in the composition is preferably 5% by mass or more, and more preferably 65% ​​by mass or less, because the fluidity of the composition allows a uniform coating film to be obtained by a coating method such as spin coating.

[0042] ·others In one embodiment, the negative photosensitive resin composition may contain various additives in addition to the above-described components (A) to (C) and solvent, provided that the additives do not impair the effects of the present invention. Examples of the additives include fillers, pigments, surfactants such as leveling agents, adhesion improvers, and dissolution promoters.

[0043] The negative photosensitive resin composition of this embodiment can be prepared by stirring and mixing the above-mentioned components (A) to (C), and, if necessary, a solvent and various additives, in a conventional manner to form a homogeneous liquid. When solid materials such as fillers and pigments are blended into the composition, they are preferably dispersed and mixed using a dispersing device such as a dissolver, homogenizer, triple roll mill, etc. The composition can also be filtered using a mesh filter, membrane filter, etc. to remove coarse particles and impurities. The negative photosensitive resin composition of this embodiment can be suitably used for dry film resist applications.

[0044] [Dry film resist] A dry film resist according to one embodiment of the present invention comprises a substrate film and a resist layer (hereinafter sometimes referred to as a resist layer or a resist film) containing the negative photosensitive resin composition of the present invention.

[0045] The substrate film may be a single-layer film made of a single polymer film or a multilayer film made by laminating multiple polymer films. Specific examples include plastic films such as nylon film, polyethylene (PE) film, polyethylene terephthalate (PET) film, polyethylene naphthalate film, polyphenylene sulfide (PPS) film, polypropylene (PP) film, polystyrene film, polymethylpentene (TPX) film, polycarbonate film, fluorine-containing film, special polyvinyl alcohol (PVA) film, and polyester film with a release treatment. Among these, polyethylene terephthalate (PET) film is preferred.

[0046] The resist layer can be obtained, for example, by forming a film of the negative photosensitive resin composition of the present invention on a substrate film using an applicator, a bar coater, a wire bar coater, a roll coater, a curtain flow coater, or the like.

[0047] In one embodiment of the dry film resist, in addition to the above-described base film and resist layer, known layers such as a film for protecting the resist layer may be laminated. The protective film is not particularly limited as long as it can be peeled off without damaging the shape of the resist layer. Specific examples include plastic films such as nylon film, polyethylene (PE) film, polyethylene terephthalate (PET) film, polyethylene naphthalate film, polyphenylene sulfide (PPS) film, polypropylene (PP) film, polystyrene film, polymethylpentene (TPX) film, polycarbonate film, fluorine-containing film, special polyvinyl alcohol (PVA) film, and polyester film with a release treatment.

[0048] The dry film resist of this embodiment can be attached to an object such as a semiconductor substrate or a semiconductor package using various laminators such as a vacuum laminator or a roll laminator, and the base film can be peeled off to transfer the resist layer to the object. The semiconductor substrate, semiconductor package, etc. may or may not have a stepped structure. By appropriately adjusting the thickness of the resist layer according to the height of the step, it is possible to fill the step with the resist layer. The dry film resist of this embodiment can be suitably used for semiconductor substrates, semiconductor packages, etc. that have steps. After the transfer, the transfer medium is subjected to heat treatment as needed, for example, on a hot plate or in an oven at 60 to 150°C for 1 to 30 minutes, preferably 80 to 130°C for 1 to 10 minutes.

[0049] A cured resist product is obtained by irradiating (exposing) the transferred resist layer with actinic rays or radiation through a negative mask capable of forming a pattern of a predetermined shape. Examples of radiation sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and argon gas lasers. Examples of radiation include microwaves, infrared rays, visible light, ultraviolet rays, X-rays, gamma rays, electron beams, proton beams, neutron beams, and ion beams. Among these light sources, ultraviolet light is preferred, and the g-ray (wavelength 436 nm) and i-ray (wavelength 365 nm) of a high-pressure mercury lamp are preferred. The radiation dose varies depending on the composition of the negative photosensitive resin composition and the film thickness of the photosensitive layer, but is typically 100 to 1,000 mJ / cm. 2 The degree is preferable.

[0050] After exposure, the desired resist pattern can be formed by developing the resist in accordance with a known method to dissolve and remove unnecessary portions. In this embodiment, the resist layer before exposure has high alkali solubility, and therefore the difference in alkali solubility between the exposed portion and the resist layer is large, making it possible to pattern with high resolution.

[0051] The developer is appropriately selected depending on the composition of the negative photosensitive resin composition. Examples of the developer include alkaline aqueous solutions of inorganic alkaline substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and cyclic amines such as pyrrole and piheridine. The alkaline developer may be used by appropriately adding alcohol, surfactant, etc., as needed. The alkaline concentration of the alkaline developer is usually preferably in the range of 2 to 5% by mass, and a 2.38% by mass aqueous solution of tetramethylammonium hydroxide is generally preferably used.

[0052] The development time varies depending on the composition of the negative photosensitive resin composition and the film thickness of the layer containing the negative photosensitive resin composition, but is usually 1 to 30 minutes. The development method may be any of a puddle method, a dipping method, a puddle method, a spray development method, etc. Development may be carried out in multiple steps while exchanging the developer.

[0053] After development with an alkaline developer, for example, washing with running water is carried out for 30 to 90 seconds, and if necessary, further heating at a temperature of 50° C. or higher and 200° C. or lower gives a cured resist pattern. A cured resist formed using the dry film resist of this embodiment has excellent chemical resistance. [Example]

[0054] The present invention will be described in more detail below with reference to specific examples. The weight average molecular weight (Mw) of the synthesized resin was measured under the following GPC measurement conditions. [GPC measurement conditions] Measuring device: Tosoh Corporation "HLC-8220 GPC" Column: Showa Denko K.K. "Shodex KF802": 8.0mmΦ x 300mm +Showa Denko KF802: 8.0mmΦ x 300mm +Showa Denko KF803: 8.0mmΦ x 300mm +Showa Denko KF804: 8.0mmΦ x 300mm Column temperature: 40℃ Detector: RI (differential refractometer) Data processing: Tosoh Corporation "GPC-8020 Model II Version 4.30" Developing solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample: 0.5% by mass of tetrahydrofuran solution converted to resin solids filtered through a microfilter Injection volume: 0.1mL Standard sample: monodisperse polystyrene as follows (Standard sample: monodisperse polystyrene) Tosoh Corporation "A-500" Tosoh Corporation "A-2500" Tosoh Corporation "A-5000" "F-1" manufactured by Tosoh Corporation "F-2" manufactured by Tosoh Corporation "F-4" manufactured by Tosoh Corporation "F-10" manufactured by Tosoh Corporation "F-20" manufactured by Tosoh Corporation

[0055] Synthesis Example 1 (Synthesis of Novolac Phenolic Resin (A-1)) A 2000 mL four-neck flask equipped with a condenser was charged with 164 g (1.52 mol) of m-cresol, 103 g (0.97 mol) of benzaldehyde, 74 g (0.61 mol) of salicylaldehyde, and 8 g of paratoluenesulfonic acid, which were then dissolved in 300 g of ethanol as the reaction solvent. The mixture was then heated to 80°C using a mantle heater and stirred under reflux for 16 hours to allow the reaction to proceed. After the reaction, ethyl acetate and water were added and the mixture was washed five times with a separation wash. The solvent was removed from the remaining resin solution by distillation under reduced pressure, and the resulting mixture was then vacuum dried, yielding 281 g of a pale red powder of novolac-type phenolic resin (A1). The Mw of the novolac phenolic resin (A-1) was 3,100. The GPC chart of the novolac phenolic resin (A-1) is shown in FIG.

[0056] Synthesis Example 2 (Synthesis of Novolac Phenolic Resin (A-2)) Except for changing the amounts of starting materials to 164 g (1.52 mol) of m-cresol, 80 g (0.75 mol) of benzaldehyde, and 92 g (0.75 mol) of salicylaldehyde, 280 g of powder of novolac type phenolic resin (A-2) was obtained in the same manner as in Synthesis Example 1. The Mw of the novolac type phenolic resin (A-2) was 2,370. The GPC chart of the novolac phenolic resin (A-2) is shown in FIG.

[0057] Synthesis Example 3 (Synthesis of Novolac Phenolic Resin (A-3)) Except for changing the amounts of starting materials to 164 g (1.52 mol) of m-cresol, 117 g (1.10 mol) of benzaldehyde, and 58 g (0.47 mol) of salicylaldehyde, the same procedure as in Synthesis Example 1 was repeated to obtain 279 g of powder of novolac phenolic resin (A-3). The Mw of the novolac phenolic resin (A-3) was 2,700. The GPC chart of the novolac phenolic resin (A-3) is shown in FIG.

[0058] Synthesis Example 4 (Synthesis of Novolac Phenolic Resin (A-4)) Except for changing the amounts of starting materials to 164 g (1.52 mol) of m-cresol, 67 g (0.63 mol) of benzaldehyde, and 115 g (0.94 mol) of salicylaldehyde, the same procedure as in Synthesis Example 1 was repeated to obtain 282 g of powder of novolac phenolic resin (A-4). The Mw of the novolac phenolic resin (A-4) was 2,900. The GPC chart of the novolac phenolic resin (A-4) is shown in FIG.

[0059] Synthesis Example 5 (Synthesis of Novolac Phenolic Resin (A-5)) Except for changing the reaction solvent to 250 g of ethanol, 30 g of 1-propanol, and 15 g of 2-propanol, the same procedure as in Synthesis Example 1 was repeated to obtain 282 g of powder of novolac phenolic resin (A-5). The Mw of the novolac phenolic resin (A-5) was 3,200. The GPC chart of the novolac phenolic resin (A-5) is shown in FIG.

[0060] Comparative Synthesis Example 1 (Synthesis of Novolac Phenolic Resin (A-6)) Under a dry nitrogen stream, a 2000 mL three-neck flask equipped with a condenser was charged with 140 g (1.30 mol) of m-cresol, 76 g (0.7 mol) of p-cresol, 151 g of 37 wt% formaldehyde aqueous solution (1.86 mol of formaldehyde), and 1 g (0.01 mol) of oxalic acid dihydrate. The mixture was dissolved in 528 g of methyl isobutyl ketone (MIBK). The reaction mixture was refluxed under a heating mantle and stirred for 4 hours. After the reaction, water was added and the mixture was washed five times with a separatory system. The methyl isobutyl ketone was removed under reduced pressure at 60°C using an evaporator, followed by vacuum drying, yielding 212 g of a pale red powder of phenol novolac resin (A-6). GPC analysis of the phenol novolac resin (A-6) showed a weight-average molecular weight (Mw) of 3,500.

[0061] [Negative-type photosensitive resin composition] Example 1 A negative photosensitive resin composition (E-1) was obtained by dissolving 10.0 g of the phenol novolak resin (A-1) powder obtained in Synthesis Example 1, 6.0 g of a radical polymerizable compound (B) (dipentaerythritol hexaacrylate manufactured by Nippon Kayaku Co., Ltd.), 1.2 g of a photopolymerization initiator (C) powder (Irgacure 369 manufactured by Sigma-Aldrich Co., Ltd.), and 25.8 g of propylene glycol monomethyl ether acetate.

[0062] Examples 2 to 5, Comparative Example 1 In Examples 2 to 5 and Comparative Example 1, negative photosensitive resin compositions (E-2) to (E-6) were obtained in the same manner as in Example 1, except that phenol novolak resin (A-2) to (A-6) powders shown in Table 1 were used as component (A).

[0063] Comparative Example 2 A negative photosensitive resin composition (E-7) was obtained in the same manner as in Example 1, except that a resin (A-7) represented by the following formula was used as component (A) instead of the phenol novolak resin. In the following formula showing the structural structure of the alkali-soluble resin, the number to the right of the parentheses indicates the content (mass%) of the unit in the parentheses in the resin. [ka]

[0064] Comparative Example 3 A negative photosensitive resin composition (E-8) was obtained in the same manner as in Example 1, except that component (A) was not used.

[0065] [evaluation] Dry film resists were prepared using the negative photosensitive resin compositions prepared in the Examples and Comparative Examples, and the film-forming properties on the substrate film, the alkali solubility and adhesion of the resist film before exposure, and the chemical resistance of the cured resist film after exposure were evaluated. (1) Film formability The negative photosensitive resin composition was applied to a PET film using a bar coater (No. 02, manufactured by Daiichi Rika Co., Ltd.) to a thickness of approximately 5 μm, and the applied film was dried at 100° C. for 60 seconds to obtain a PET film with a photosensitive film formed thereon. The photosensitive film formed on the PET film surface was observed using an optical microscope to evaluate repellency and unevenness during film formation. Those without repellency or unevenness were rated as having good film-forming properties (◯), and those with repellency or unevenness were rated as having insufficient film-forming properties (×). The evaluation results are shown in Table 1.

[0066] (2) Alkali solubility The negative photosensitive resin composition was applied to a PET film to a thickness of approximately 5 μm using a bar coater (No. 02, manufactured by Daiichi Rika Co., Ltd.), and the coating was dried at 100°C for 60 seconds to obtain a PET film with a photosensitive film. The resulting PET film was immersed for 10 seconds in a tray containing 250 mL of developer (2.38% aqueous tetramethylammonium hydroxide solution), and then the removed PET film was rinsed with pure water for 10 seconds to evaluate the residue on the PET film. Those with no residue were rated as good (◯), and those with residue were rated as poor (×). The evaluation results are shown in Table 1.

[0067] (3) Adhesion The negative photosensitive resin composition was applied to a copper plate (Standard Test Piece Co., Ltd. C1020) using a bar coater (Daiichi Rika Co., Ltd.: No. 02) to a thickness of approximately 5 μm. The coating was then dried at 100°C for 60 seconds to obtain a copper plate with a photosensitive film. The resulting photosensitive film was divided into a grid pattern of 25 squares spaced 2 mm apart using a utility knife. Cellophane tape was firmly applied to the grid pattern area of ​​the photosensitive film, and the tape was peeled off within 1 second within 5 minutes. The peeling of the grid pattern area was observed (based on the JIS 5400 cross-cut test). The evaluation results are shown in Table 1.

[0068] (4) Chemical resistance of the cured film The negative photosensitive resin composition was applied to a silicon wafer with a diameter of 5 inches to a thickness of approximately 5 μm using a bar coater (manufactured by Daiichi Rika Co., Ltd.: No. 02), and then dried at 100°C for 60 seconds. Thereafter, the composition was irradiated with 200 mJ / cm using a UV irradiation device (manufactured by Minei Electric Co., Ltd.: UVE-1001SD). 2 After irradiation with light, the wafer was baked at 130° C. for 180 seconds to obtain a wafer on which a cured film was formed. After measuring the film thickness of the resulting wafer, it was divided into two. One of the two pieces was immersed in a 50 wt% aqueous solution of sulfuric acid (simulating a plating solution), and the other in a 2.38 wt% aqueous solution of TMAH for 15 minutes. After removing the wafer from the solution and washing it with pure water, the film thickness was measured again. Chemical resistance was evaluated based on the rate of change in film thickness before and after immersion in a solvent. A rate of change of less than 2% was rated as good (◯), and a rate of change of 2% or more was rated as poor (×). The evaluation results are shown in Table 1.

[0069] [Table 1]

[0070] In Table 1, the molar ratio of the structural units of component (A), "(a1) / (a2) / (a3)," is the molar ratio of the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde.

[0071] From Table 1, it can be seen that the dry film resist using the negative photosensitive resin composition of the present invention does not cause film formation defects. It can also be seen that the resist film has alkali solubility and high adhesion. Furthermore, it can be seen that the cured resist film has excellent chemical resistance.

Claims

1. A negative photosensitive resin composition comprising the following components (A) to (C): (A) A novolak-type phenolic resin in which the molar ratio of the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde [(a1):(a2):(a3)] is 1.0:0.5-0.7:0.3-0.

5. (B) Radical polymerizable compound (C) Photopolymerization initiator

2. 2. The negative photosensitive resin composition according to claim 1, wherein the total content of the structural unit (a1) derived from m-cresol, the structural unit (a2) derived from benzaldehyde, and the structural unit (a3) ​​derived from salicylaldehyde in component (A) is 30% by mass or more.

3. The negative photosensitive resin composition according to claim 1 or 2, further comprising a solvent.

4. A dry film resist comprising a substrate film and a resist layer comprising the negative photosensitive resin composition according to claim 1 or 2.

5. A cured product of the resist layer according to claim 4.

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