Photosensitive resin composition, resist film, resist underlayer film, and permanent resist film

Abstract

To provide a positive photosensitive resin composition that features alkali solubility and photosensitizer affinity, characteristics not found in traditional positive photosensitive resin compositions, while also exhibiting low-temperature curability and low volumetric contraction when in a resist film form.SOLUTION: A positive photosensitive resin composition includes the following components (A)-(D). (A) A novolac phenolic resin including an m-cresol-derived structural unit (a1), a benzaldehyde-derived structural unit (a2), and a salicylaldehyde-derived structural unit (a3), with the molar ratio [(a1):(a2):(a3)] being 1.0:0.3-0.8:0.3-0.8. (B) A photosensitizer. (C) A heat crosslinker. (D) An organic solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photosensitive resin composition, a resist film, a resist underlayer film, and a permanent resist film. [Background technology]

[0002] In recent years, as electronic devices have become smaller, the density of semiconductor packages has increased. This increase in density of semiconductor packages is linked to the demand for further miniaturization of semiconductor elements, and fine patterns of several micrometers are required for surface protection films, interlayer insulating films, etc.

[0003] Positive-type photosensitive resin compositions using polyimide resins and the like, which have excellent heat resistance and mechanical properties, have traditionally been widely used for surface protective films and interlayer insulating films of semiconductor elements. Typically, polyimide resin precursor coatings are formed into resin coatings by heat curing to close the ring. These resin coatings have excellent heat resistance and mechanical properties. However, positive-type photosensitive resin compositions using polyimide precursors suffer from volumetric shrinkage due to dehydration during heat curing, resulting in loss of film thickness and reduced dimensional accuracy. Furthermore, while low-temperature film formation processes have been desired in recent years, there is a problem in that satisfactory physical properties cannot be obtained when polyimides are cured at low temperatures due to incomplete imidization.

[0004] In response to this, a positive-type photosensitive resin composition has been proposed that uses a phenolic resin, a photosensitizer, and a thermal crosslinking agent, which does not dehydrate when cured by heating, can be cured at low temperatures, and has excellent mechanical properties after curing (for example, Patent Document 1).However, in the positive-type photosensitive resin composition described in Patent Document 1, the base phenolic resin has poor alkali solubility and poor affinity for the photosensitizer, making it unsuitable for forming fine patterns.

[0005] Therefore, in order to realize the formation of fine patterns, positive-type resin compositions using modified phenolic resins have also been proposed (for example, Patent Document 2). However, the positive-type photosensitive resin composition described in Patent Document 2 still has problems with the alkali solubility of the phenolic resin and the affinity for the photosensitizer, and satisfactory fine pattern formation has not been realized. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-258070 [Patent Document 2] International Publication No. 2009 / 063808 Summary of the Invention [Problem to be solved by the invention]

[0007] As semiconductor packages become denser and patterns become finer, there is a demand for the development of positive-tone photosensitive resin compositions that are made from phenolic resins that have high alkali solubility and high photosensitizer affinity, and that exhibit low-temperature curing properties and low volume shrinkage when used to form resist films.

[0008] An object of the present invention is to provide a positive photosensitive resin composition that has alkali solubility and photosensitizer affinity not found in conventional positive photosensitive resin compositions, and that has low-temperature curing properties and low volume shrinkage when formed into a resist film. [Means for solving the problem]

[0009] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a positive-type photosensitive resin composition containing a novolac-type phenolic resin composition having a specific structural unit, a photosensitizer, a thermal crosslinker, and an organic solvent has excellent alkali solubility and affinity for the photosensitizer, and when formed into a resist film, has excellent low-temperature curing properties and low volume shrinkage, and have completed the present invention.

[0010] That is, the present invention relates to a positive photosensitive resin composition containing the following components (A) to (D): (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) Photosensitizer (C) Thermal crosslinking agent (D) Organic solvent The present invention further relates to a photosensitive film obtained by drying the positive photosensitive resin composition. The present invention further relates to a resist film obtained from the positive photosensitive resin composition. The present invention further relates to a resist underlayer film obtained from the positive photosensitive resin composition. The present invention further relates to a permanent resist film obtained from the positive photosensitive resin composition. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a positive photosensitive resin composition that has excellent alkali solubility and photosensitizer affinity, and when formed into a resist film, has excellent low-temperature curing properties and low volume shrinkage. [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] [Positive-type photosensitive resin composition] A positive photosensitive resin composition according to one embodiment of the present invention contains the following components (A) to (D). (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) Photosensitizer (C) Thermal crosslinking agent (D) Organic solvent

[0015] In this embodiment, by using the novolac type phenolic resin (A) above, a resist film having excellent affinity for photosensitizers in addition to high alkali solubility can be obtained. The components of the positive 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 resist film that has high alkali solubility, photosensitizer affinity, low-temperature curing ability, and low volume shrinkage.

[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 resist film that has high alkali solubility, photosensitizer affinity, low-temperature curing ability, and low volume shrinkage. 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 excellent low-temperature curing properties and low volume shrinkage. On the other hand, a weight-average molecular weight of 7,000 or less is preferred because it provides excellent alkali solubility and photosensitizer affinity. 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, and more preferably 1.0:0.55-0.65:0.35-0.45, from the viewpoint of obtaining a resist film that has high alkali solubility, photosensitizer affinity, low-temperature curing ability, and low volume shrinkage.

[0025] The molar ratio of benzaldehyde is preferably smaller than the molar ratio of salicylaldehyde, i.e., it is preferable to satisfy the molar ratio benzaldehyde<salicylaldehyde.

[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 mass % or more, more preferably 50 mass % or more, and even more preferably substantially 100 mass %, from the viewpoint of obtaining a resist film that has high alkali solubility, photosensitizer affinity, low-temperature curing ability, and low volume shrinkage.

[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 photosensitizer, which is component (B), can improve the sensitivity during exposure by promoting alkali solubilization of the exposed area of ​​the coating film of the positive photosensitive resin composition. In order to impart high photosensitizer affinity to the positive photosensitive resin composition of the present invention, the photosensitizer is preferably a quinonediazide-based photosensitizer.

[0033] The quinone diazide photosensitizer includes a compound having a quinone diazide group. Specific examples of the compound having a quinone diazide group include a complete ester compound, a partial ester compound, an amidation product, or a partial amidation product of an aromatic (poly)hydroxy compound and a sulfonic acid having a quinone diazide group, such as naphthoquinone-1,2-diazide-5-sulfonic acid, naphthoquinone-1,2-diazide-4-sulfonic acid, or orthoanthraquinone diazide sulfonic acid.

[0034] Examples of aromatic (poly)hydroxy compounds include polyhydroxybenzophenone compounds such as 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,6-trihydroxybenzophenone, 2,3,4-trihydroxy-2'-methylbenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3',4,4',6-pentahydroxybenzophenone, 2,2',3,4,4'-pentahydroxybenzophenone, 2,2',3,4,5-pentahydroxybenzophenone, 2,3',4,4',5',6-hexahydroxybenzophenone, and 2,3,3',4,4',5'-hexahydroxybenzophenone;

[0035] bis[(poly)hydroxyphenyl]alkane compounds such as bis(2,4-dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, 2-(4-hydroxyphenyl)-2-(4'-hydroxyphenyl)propane, 2-(2,4-dihydroxyphenyl)-2-(2',4'-dihydroxyphenyl)propane, 2-(2,3,4-trihydroxyphenyl)-2-(2',3',4'-trihydroxyphenyl)propane, 4,4'-{1-[4-[2-(4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol, and 3,3'-dimethyl-{1-[4-[2-(3-methyl-4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol;

[0036] tris(hydroxyphenyl)methane compounds or methyl-substituted compounds thereof, such as tris(4-hydroxyphenyl)methane, bis(4-hydroxy-3,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, and bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane;

[0037] Bis(3-cyclohexyl-4-hydroxyphenyl)-3-hydroxyphenylmethane, Bis(3-cyclohexyl-4-hydroxyphenyl)-2-hydroxyphenylmethane, Bis(3-cyclohexyl-4-hydroxyphenyl)-4-hydroxyphenylmethane, Bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-2-hydroxyphenylmethane, Bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-hydroxyphenylmethane, Bis(5-cyclohexyl-4-hydroxy-2 -methylphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-4-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-4-hydroxy phenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-4-hydroxyphenylmethane, and the like, and bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methane compounds and methyl-substituted derivatives thereof. These photosensitizers may be used alone or in combination of two or more.

[0038] The photosensitizer may be used alone or in combination of two or more kinds. In this embodiment, the amount of the photosensitizer to be added is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, per 100 parts by mass of component (A), in order to obtain a positive photosensitive resin composition having excellent photosensitivity and excellent photosensitizer affinity, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less.

[0039] ·Component (C) The thermal crosslinking agent, component (C), is a compound that forms a crosslinked structure in the resist film when the resist film is cured by heating after a pattern is formed on a coating film of the positive photosensitive resin composition. In this embodiment, if component (C) is not included, the positive photosensitive resin composition will not cure sufficiently when used as a resist film.

[0040] The thermal crosslinking agent is not particularly limited, and a known thermal crosslinking agent can be used. Examples of the thermal crosslinking agent include epoxy-based thermal crosslinking agents and hydroxymethylamino-based thermal crosslinking agents. In this embodiment, from the viewpoint of obtaining a resist film having low-temperature curing properties and low volume shrinkage, a hydroxymethylamino-based thermal crosslinking agent is preferred.

[0041] Epoxy-based thermal crosslinking agents use compounds having epoxy groups as thermal crosslinking agents. Examples of epoxy-based thermal crosslinking agents include bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, alicyclic epoxy resins, glycidyl amines, heterocyclic epoxy resins, and polyalkylene glycol diglycidyl ethers.

[0042] Hydroxymethylamino-based thermal crosslinking agents use a compound having a hydroxymethylamino group as the thermal crosslinking agent. Examples of hydroxymethylamino-based thermal crosslinking agents include (poly)(N-hydroxymethyl)melamine. Specific examples include melamine resins such as hexakis(methoxymethyl)melamine and hexakis(butoxymethyl)melamine. Additionally, examples of hydroxymethylamino-based thermal crosslinking agents include urea resins. Specific examples include Nikalac MX-270, MX-280, and MX-290 (manufactured by Sanwa Chemical Co., Ltd.).

[0043] The thermal crosslinking agent may be used alone or in combination of two or more kinds. The amount of the thermal crosslinking agent to be added is preferably 5 parts by mass or more, more preferably 10 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.

[0044] ·Component (D) The positive photosensitive resin composition of this embodiment contains an organic solvent as component (D). Examples of organic solvents 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, propylene glycol monoethyl 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 organic solvents may be used alone or in combination of two or more.

[0045] The amount of organic solvent blended in the positive 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.

[0046] ·others In one embodiment, the positive photosensitive resin composition may contain various additives in addition to the above-described components (A) to (D) within the range that does not impair the effects of the present invention. Examples of additives include fillers, pigments, surfactants such as leveling agents, adhesion improvers, and dissolution promoters.

[0047] The positive photosensitive resin composition of this embodiment can be prepared by stirring and mixing the above-mentioned components (A) to (D), and various additives as needed, 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.

[0048] The positive photosensitive resin composition of this embodiment can be suitably used for applications such as resist films, resist underlayer films, and permanent resist films. It can also be suitably used for thick-film resists (bump-forming resists), interlayer insulating films, liquid crystal alignment films, heat resistance imparting agents, and bank agents (pixel dividing layers) for displays.

[0049] The positive photosensitive resin composition of the present invention can be used in the same manner as a general positive photosensitive resin composition to produce a photosensitive film, a resist film, a resist underlayer film, and a permanent resist film (hereinafter, the photosensitive film, the resist film, the resist underlayer film, and the permanent resist film may be collectively referred to as a resist film, etc.). Specifically, the positive photosensitive resin composition of the present invention is applied to an object to be subjected to photolithography, and then prebaked to obtain a film of the photosensitive resin composition (photosensitive film) from which the organic solvent has been removed.

[0050] Examples of application methods include spin coating, roll coating, flow coating, dip coating, spray coating, and doctor blade coating. Pre-baking may involve heating at a temperature of 60°C to 150°C for 30 to 600 seconds. The positive photosensitive resin composition of the present invention can be applied to a substrate appropriately selected from glass substrates, silicon substrates, aluminum substrates, silicon carbide substrates, silicon nitride substrates, gallium nitride substrates, transparent conductive films, copper substrates, copper-plated substrates, and the like.

[0051] The catalytic reaction of the acid generated by exposing the photosensitive film to light significantly increases the solubility of the exposed area in an alkaline developer. Examples of light sources used for exposure include infrared light, visible light, ultraviolet light, far-ultraviolet light, X-rays, and electron beams. Among these light sources, ultraviolet light is preferred, and the g-line (wavelength 436 nm) and i-line (wavelength 365 nm) of a high-pressure mercury lamp are suitable. After exposure, the film may be heat treated at about 100°C to 150°C.

[0052] The photosensitive film obtained from the positive photosensitive resin composition of the present invention has high alkali solubility in the exposed area and a large difference in alkali solubility between the exposed area and the unexposed area, allowing for high-resolution patterning. Therefore, the composition can be suitably used as a resist film, etc. In this application, the term "resist film, etc." includes both a photosensitive film before exposure and a non-photosensitive film after exposure.

[0053] Examples of alkaline developers used for development after exposure 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 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 used.

[0054] When the positive photosensitive resin composition of the present invention is used for a resist underlayer film (BARC film), the positive photosensitive resin composition of the present invention may be used as it is as a composition for a resist underlayer film, or various additives such as other resin components, surfactants, dyes, fillers, crosslinking agents, and dissolution promoters may be added, if necessary.

[0055] Examples of other resin components include various novolak resins, addition polymerization resins of alicyclic diene compounds such as dicyclopentadiene and phenolic compounds, modified novolak resins of phenolic hydroxyl group-containing compounds and alkoxy group-containing aromatic compounds, phenol aralkyl resins (Zylok resins), naphthol aralkyl resins, trimethylolmethane resins, tetraphenylolethane resins, biphenyl-modified phenolic resins, biphenyl-modified naphthol resins, aminotriazine-modified phenolic resins, and various vinyl polymers. When other resin components are used, the blending ratio of the positive photosensitive resin composition of the present invention to the other resins can be set as desired depending on the application. For example, the blending ratio is preferably 0.5 to 100 parts by mass of the other resins per 100 parts by mass of component (A).

[0056] The composition for a resist underlayer film can be prepared by blending the above-mentioned components and mixing them using a stirrer, etc. Furthermore, when the composition for a resist underlayer film contains a filler or a pigment, it can be prepared by dispersing or mixing using a dispersing device such as a dissolver, a homogenizer, or a three-roll mill.

[0057] To form a resist underlayer film from the resist underlayer film composition, for example, the above-described resist underlayer film composition is applied to an object to be photolithographed, such as a silicon substrate, dried at a temperature of 100 to 200° C., and then further cured by heating at a temperature of 250 to 400° C. Next, a resist pattern is formed on this underlayer film by performing a normal photolithography operation, and a dry etching treatment is performed with a halogen-based plasma gas or the like, thereby forming a resist pattern by a multilayer resist method.

[0058] When the positive photosensitive resin composition of the present invention is used for a permanent resist film, in addition to the components (A) to (D) of the present invention, additives such as other resins, surfactants, dyes, fillers, crosslinking agents, dissolution promoters, etc. Examples of other resins used here include the same resins that can be used in compositions for resist underlayer films.

[0059] In a photolithography method using a composition for a permanent resist film, for example, other resin components and additive components are dissolved or dispersed in the positive photosensitive resin composition of the present invention, and the composition is applied to an object to be photolithographed, followed by pre-baking at a temperature of 60 to 150° C. The application method may be any of spin coating, roll coating, flow coating, dip coating, spray coating, doctor blade coating, etc. Next, the desired resist pattern is exposed through a predetermined mask, and the exposed areas are dissolved in an alkaline developer to form a resist pattern.

[0060] The permanent resist film of this embodiment can be suitably used, for example, in semiconductor devices, as solder resist, packaging material, underfill material, package adhesive layer for circuit elements, and adhesive layer between integrated circuit elements and circuit boards, and in thin-film displays such as LCDs and OLEDs, as thin-film transistor protective films, liquid crystal color filter protective films, black matrices, spacers, and the like. [Example]

[0061] 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

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Comparative Synthesis Example 1 (Synthesis of Novolac Phenolic Resin (A-6)) Under a dry nitrogen stream, 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 were charged into a 2000 mL three-neck flask equipped with a condenser. 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 to obtain 212 g of a pale red powder of phenol novolac resin (A-6). The Mw of the phenol novolac resin (A-6) was 3,500.

[0068] Comparative Synthesis Example 2 (Synthesis of Novolac Phenolic Resin (A-7)) Under a dry nitrogen stream, 100 g of a mixture of m-cresol and p-cresol in a weight ratio of 60:40, 11 g of tung oil (manufactured by Yamakei Sangyo Co., Ltd.), and 0.01 g of p-toluenesulfonic acid were placed in a 250 mL four-neck flask equipped with a condenser, and the mixture was stirred at 120°C for 2 hours to obtain compound (a-7), a drying oil-modified phenol derivative. Next, 100 g of the compound (a-7), 13.9 g of paraformaldehyde, and 0.9 g of oxalic acid were mixed and reacted at 90°C for 3 hours with stirring. The mixture was then heated to 120°C and stirred under reduced pressure for 3 hours. The reaction mixture was then cooled to room temperature under atmospheric pressure, yielding 102 g of the reaction product, a drying oil-modified phenolic resin (A-7). The Mw of the phenolic novolac resin (A-7) was 12,900.

[0069] [Positive-type photosensitive resin composition] Example 1 1.00 g of the phenol novolak resin (A-1) powder obtained in Synthesis Example 1, 0.15 g of a photosensitizer (1,2-naphthoquinone diazide (P-200: manufactured by Toyo Gosei Co., Ltd.)) powder (B), and 0.15 g of a thermal crosslinker (methylated melamine resin (Nicalac MW-30HM: manufactured by Sanwa Chemical Co., Ltd.)) powder (C-1) were dissolved in 18 g of propylene glycol monomethyl ether acetate (D) to obtain a positive photosensitive resin composition (E-1).

[0070] Examples 2 to 5 Positive photosensitive resin compositions (E-2) to (E-5) were obtained in the same manner as in Example 1, except that phenol novolak resin (A-2) to (A-5) powders shown in Table 1 were used as component (A).

[0071] Example 6 A positive photosensitive resin composition (E-6) was obtained in the same manner as in Example 1, except that a thermal crosslinking agent (methylated urea resin (Nicalac MX-270: manufactured by Sanwa Chemical Co., Ltd.)) powder (C-2) was used as component (C).

[0072] Comparative Examples 1-2 Positive photosensitive resin compositions (E-7) to (E-8) were obtained in the same manner as in Example 1, except that phenol novolak resin (A-6) and (A-7) powder shown in Table 1 were used as component (A).

[0073] [evaluation] Resist films were prepared using the positive photosensitive resin compositions prepared in the Examples and Comparative Examples, and the alkali solubility, photosensitizer affinity, low-temperature curing property, and low volume shrinkage were evaluated. (1) Alkali solubility The positive photosensitive resin composition was applied to a 5-inch silicon wafer to a thickness of approximately 1 μm using a spin coater, and then dried on a hot plate at 110°C for 60 seconds. Thereafter, a UV exposure device (UVE-1001SD manufactured by Minaga Electric Works, Ltd.) was used to apply 200 mJ / cm 2After exposure, a post-exposure bake (PEB) was performed on a hot plate at 130°C for 90 seconds. The wafer with the resulting resist film was immersed in a developer (2.38% aqueous tetramethylammonium hydroxide (TMAH) solution) for 60 seconds, and then dried on a hot plate at 110°C for 60 seconds. The film thickness was measured before and after immersion in the developer, and the difference was divided by 60 to obtain the alkali solubility ADR1 (Å / s). The evaluation criteria are as follows: 〇: ADR1 is 400 or more ×: ADR1 is less than 400 The evaluation results are shown in Table 1. The values ​​in parentheses in Table 1 are the values ​​for ADR1.

[0074] (2) Photosensitive agent affinity (development contrast) In addition, in the above (1), the value measured without exposing the resist film was defined as ADR2 (Å / s), and the value of ADR1 / ADR2 was evaluated as the affinity for the photosensitizer (development contrast). The evaluation criteria are as follows: 〇: Photosensitizer affinity is 10 or more ×: Photosensitizer affinity is less than 10 The evaluation results are shown in Table 1. The values ​​in parentheses in Table 1 are (ADR1 / ADR2).

[0075] (3) Low-temperature curing of resist film The positive photosensitive resin composition was applied to a silicon wafer with a diameter of 5 inches using a spin coater to a thickness of approximately 10 μm, and after pre-baking at 110°C for 60 seconds, it was subjected to a heat treatment (curing) at 175°C for 1 hour in a nitrogen atmosphere. When the temperature reached 50°C or below, the wafer with the resist film was removed and the film thickness was measured. The wafer with the resist film was then divided into three equal parts, and each was immersed in a solvent of acetone, N-methylpyrrolidone (NMP), and a 2.38 wt% TMAH aqueous solution for 15 minutes. After removing the wafer from each solvent, the wafer was washed with pure water and the film thickness was measured again. The low-temperature curability was evaluated based on the rate of change in film thickness before and after immersion in a solvent. The evaluation criteria were as follows: ○: The rate of change is less than 5% ×: The rate of change is 5% or more The evaluation results are shown in Table 1. The values ​​in parentheses in Table 1 are the film thickness change rates (%).

[0076] (4) Volume shrinkage of resist film The positive photosensitive resin composition was applied to a silicon wafer with a diameter of 5 inches using a spin coater to a thickness of approximately 10 μm, and then pre-baked at 110°C for 60 seconds. This was followed by a heat treatment (curing) at 175°C for 1 hour in a nitrogen atmosphere. When the temperature dropped to 50°C or below, the wafer with the resist film was removed, and the shrinkage rate of the film thickness before and after curing was calculated using the formula [1 - (film thickness after curing / film thickness before curing)] x 100, and this rate of change was taken as volume shrinkage. The evaluation criteria were as follows: ○: The rate of change is less than 10% ×: The rate of change is 10% or more The evaluation results are shown in Table 1. The values ​​in parentheses in Table 1 are volumetric shrinkage rates (%).

[0077] [Table 1]

[0078] 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.

[0079] From Table 1, it can be seen that the resist film using the positive photosensitive resin composition of the present invention has alkali solubility and high affinity for photosensitizers, and furthermore, when formed into a resist film, it also has excellent low-temperature curing properties and low volume shrinkage.

Claims

1. A positive-type photosensitive resin composition containing the following components (A) to (D) (excluding cases where the composition contains one or more resins selected from polyimide, polybenzoxazole, polyimide precursor, and polybenzoxazole precursor): (A) 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, a novolac phenolic resin satisfying the molar ratio of the structural unit (a2) derived from benzaldehyde to the structural unit (a3) ​​derived from salicylaldehyde; (B) Photosensitizer (C) a thermal crosslinking agent which is a melamine resin or a urea resin (provided that the content of the thermal crosslinking agent (C) is 5 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the novolac phenolic resin (A)). (D) Organic solvent

2. 2. The positive photosensitive resin composition according to claim 1, wherein the component (A) is a novolak phenolic resin obtained by polycondensing m-cresol, benzaldehyde, and salicylaldehyde in an organic solvent in a molar ratio of m-cresol:benzaldehyde:salicylaldehyde=1.0:0.3-0.8:0.3-0.8 using an acid catalyst.

3. 2. The positive 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.

4. 2. The positive photosensitive resin composition according to claim 1, wherein the component (B) is a quinone diazide-based photosensitive compound.

5. A photosensitive film obtained by drying the positive photosensitive resin composition according to any one of claims 1 to 4.

6. A resist film obtained from the positive photosensitive resin composition according to any one of claims 1 to 4.

7. A resist underlayer film obtained from the positive photosensitive resin composition according to any one of claims 1 to 4.

8. A permanent resist film obtained from the positive photosensitive resin composition according to any one of claims 1 to 4.

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