JPH0368065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel photosensitive resin composition, more specifically, it has excellent stability and solubility in a solution state,
The present invention relates to an aliphatic polyimide-based photosensitive resin composition that does not cause exposure damage due to whitening during the formation of a photosensitive coating film and can impart highly practical heat resistance, photosensitivity, etc., and a method for producing the same.

In recent years, new innovations have been seen in electronic devices, such as higher density, higher reliability, smaller size, and lighter weight. Photoresist materials for circuit formation are functional materials that greatly contribute to these efforts, and have realized so-called microfabrication. Furthermore, in the fields of IC and LSI, in addition to such microfabrication, the use of organic materials for interlayer insulation, which was previously done with inorganic materials, is becoming widespread, and materials with excellent heat resistance such as polyimide resin are being used mainly. It has come to be used. However, this material still requires photoresist to process patterns such as through holes, and this photoresist process is long and complicated, so even after forming a circuit by exposure and development, the resist remains as it is. There is a strong desire for the emergence of a heat-resistant photoresist that can be used as an insulating material.

As these materials, heat-resistant photoresists based on photosensitive polyimide and cyclized polybutadiene have been proposed, and aromatic polyimides in particular have excellent properties due to their polyimide skeleton, and their production is difficult. Many proposals have been made to use it in photosensitive materials because it is easy to remove impurities. Such photosensitive polyimides are processed in the form of a precursor (polyamic acid) and imidized by post-curing, as in the case of ordinary aromatic polyimides.

As these photosensitive polyimides, a system consisting of a polyimide precursor and a dichromate was first proposed (Japanese Patent Publication No. 17374/1973), but this photosensitive composition had the disadvantage of an extremely short pot life. In addition to these disadvantages, there are other disadvantages such as the development process is complicated and long, and chromium ions remain in the polyimide film.
It was not put into practical use. As another example, a photosensitive polyimide precursor has been proposed in which a photosensitive group is introduced into a polyimide precursor through an ester bond (Japanese Patent Publication No. 30207/1983), but this also requires Since it involves a dehydrochloric acid reaction, chlorine ions remain in the solution, and their removal poses a problem. In order to avoid such problems such as impurities, there are methods of mixing a photosensitive compound with a polyimide precursor and selectively reacting the functional groups of the polyimide compound precursor with the functional groups of a compound having a photosensitive group. Methods for introducing groups have also been developed. Furthermore, a method for obtaining a photosensitive polyimide precursor using a monomer having a photosensitive group is also known.

However, from the viewpoint of heat resistance, aromatic polyimide precursors synthesized from pyromellitic dianhydride and 4,4'-diaminodiphenyl ether are used as the backbone polymers of these photosensitive polyimides. , these series of photosensitive polyimides include the drawbacks of conventional aromatic polyimide precursors. That is, solutions containing the above-mentioned precursors have essential problems in solubility, and also have major practical defects in their stability as solutions, such as partial insolubilization due to imidization during storage. Improvements are desired.

This problem of solubility is a problem, for example, even when preparing a solution in which an aromatic polyimide precursor and a compound having a photosensitive group are uniformly dissolved as a photosensitive polyimide, most of the problems occur during the drying process to form a coating film from this solution. The good solvent evaporates, and the dried coating film is composed of the precursor and a compound having a photosensitive group. Compounds having such photosensitive groups are generally poor solvents for the precursors, and a whitening phenomenon occurs in the dried coating due to the insolubilization of the precursors, making it difficult to use them in the exposure process. Put it away. Furthermore, according to the observations of the present inventors, a strange phenomenon has been discovered in which a compound having a photosensitive group evaporates at the same time as the solvent during the formation of a dry paint film, and although there is no phenomenon of paint film whitening, photosensitivity is lost. . Therefore, the compounds having a photosensitive group that can be used are currently limited to special compounds (for example, compounds that are expensive or have a bad odor) in terms of solubility or compatibility.

Under these circumstances, the present inventor has developed a material that has excellent stability and solubility in a solution state, has no exposure problems such as whitening during formation of a photosensitive coating film, and has high practical heat resistance.
The present invention was developed as a result of intensive studies to develop a photosensitive resin composition that can be provided with a photosensitive group.

That is, the present invention provides a monomer unit of an aliphatic tetracarboxylic acid and a diamine, which are obtained by reacting as monomer units, have an acid value residual rate of 40% or less, have an imide bond in the molecule, and have a carboxyl group and an amino group at the end of the molecule. A polymerizable unsaturated compound and a photopolymerization initiator are blended into a solution containing a polyimide precursor, and the coating film after drying has a novel photosensitivity that substantially allows light to pass through and provides active photosensitivity. A resin composition is provided.

In the present invention, the polyimide precursor which has an acid value residual rate of 40% or less, has an imide bond in the molecule, and has a carboxyl group and an amino group at the end of the molecule uses an aliphatic tetracarboxylic acid and a diamine as starting materials. It can be obtained by reacting in an organic solvent that is substantially inert to the organic solvent. Since the above-mentioned polyimide precursor is obtained by reacting an aliphatic tetracarboxylic acid with a diamine, it has a molecular structure in which only imide bonds are formed within the molecule and there are substantially no amic acid units. There is.

In the present invention, aliphatic tetracarboxylic acids include tetracarboxylic acids such as butane, pentane, hexane, cyclopentane, bicyclohexene, 5-(1,2-dicarboxyethyl)-3-
Methyl-3-cyclohexene-1,2-dicarboxylic acid, bicyclo-(2.2.2)-octane-2.
Examples include 3,5,6-tetracarboxylic acid. Of course, the skeleton of these tetracarboxylic acids may be substituted with a substituent such as an alkyl group, and it is also possible to partially use aliphatic dicarboxylic acids, tricarboxylic acids, or their anhydrides.

The diamine to be reacted with these aliphatic tetracarboxylic acids is a diamine represented by the general formula _H2N -R'- _NH2 , where R' is a divalent organic group, and aromatic, aliphatic, or aliphatic. It can be a cyclic group, a heterocyclic group, a combination thereof, or a group in which these are bonded with oxygen, nitrogen, sulfur, phosphorus, silicon, etc. In this case, R' may have a substituent that does not quantitatively react with the amino group or carboxyl group under the reaction conditions. These groups affect the solubility, processability, and
Alternatively, it is possible to impart desirable properties such as adhesiveness. It is also possible to use commonly used triamines or tetraamines.

Although aromatic diamines are preferred as diamines, specific examples of diamines used in the present invention include metaphenylene diamine, paraphenylene diamine, 4,4'-diaminodiphenylpropane, and 4,4'-diaminodiamine. Diphenylethane, 4.
4′-diaminodiphenylmethane, benzidine,
4,4'-diaminodiphenyl sulfide, 4,
4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, parabis-(4-aminophenoxy)benzene, metabis-(4-
aminophenoxy)benzene, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-diaminobenzanilide, 4-
(para-aminophenoxy)-4-aminobenzanilide, 3,4'-diaminodiphenyl ether,
3,3'dimethoxybenzidine, 2,4-bis(beta-amino-tert-butyl)toluene, bis(para-beta-amino-tert-butylphenyl) ether, metaxylylene diamine, para-xylylene diamine, di(para-amino- cyclohexyl)methane, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, 4,4-dimethylheptamethylene diamine, 3-methoxy-heptamethylene diamine, 2,11-diaminododecane,
1,4-diaminocyclohexane, 2,2'-diamino diethyl ether, 2,2'-diamino diethyl thioether, 3,3'-diamino dipropoxyethane, 2,6-diamino pyridine, guanamine,
2,5-diamino-1,3,4-oxadiazole, 2-(3'-aminophenyl)-5-aminobenzoxazole, bis-(4-aminophenylphosphine oxide, bis-(4-amino- (phenyl)diethylsilane, etc., and these may be used alone or as a mixture.

The reaction between an aliphatic tetracarboxylic acid and a diamine in the present invention is usually carried out in an organic solvent.

Solvents used in this reaction include N/N-dimethylformamide, N/N-diethylformamide, N/N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylenesulfone, Examples include tetramethylurea, hexamethylphosphoamide, pyridine, quinoline, γ-butyllactone, N-acetyl-2-pyrrolidone, phenol, cresols, glycols, cellosolves, carbitols, and the like. The amount of this organic solvent used is 20 to 95% by weight of the reaction system, but in some cases, the reaction between the aliphatic tetracarboxylic acid and the diamine may be carried out in the presence of a polymerizable unsaturated compound and an initiator. Therefore, the amount used may be appropriately determined so as to obtain a concentration that shows a practical viscosity. The molar ratio of aliphatic tetracarboxylic acid and diamine used is preferably equimolar. However, a few mol%
It is also possible under an excess of either position. The reaction temperature is desirably 60°C or higher, up to the boiling point under normal pressure, particularly from 80°C to the boiling point.

In the above reaction, mainly two carboxyl groups react with each amino group to cause imidization, and a solution of a polyimide precursor having an imide bond in the molecule and a carboxyl group and an amino group at the end of the molecule is formed. can get. In this case, this reaction is carried out by measuring the acid value of the reaction system, that is, the acid value due to the carboxylic acid component in the system at the initial stage of the reaction (the acid value is determined by measuring 1 g of sample).
(expressed in mg equivalent of carboxyl group per unit) 100
The extent of the reaction can be determined by the acid value residual rate, which indicates how many carboxyl groups remain after the reaction.

Therefore, the polyimide precursor in the present invention is one that has undergone a reaction until its acid value residual rate is 40% or less, and if the acid value residual rate is 40%, the reaction is insufficient. Its use should be avoided because it tends to cause coating film defects due to foaming when polyimide is formed by baking the resin pattern after exposure and development, and the mechanical strength of the coating film obtained by baking is poor.

There are various types of polymerizable unsaturated compounds in the composition of the present invention, but acrylic acid compounds, methacrylic acid compounds, compounds having an allyl group, etc. are practical. Specific acrylic acid compounds include acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, benzyl acrylate, 2
- Ethylhexyl acrylate, carbitol acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, butylene glycol monoacrylate, N/N-dimethylaminoethyl acrylate, N/N-diethylaminoethyl acrylate, Tetrahydrofurfuryl acrylate, allyl acrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexane glycol diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, 2,2 -bis-(4-acryloxydiethoxyphenyl)propane, 2,2-bis-(4
-Acryloxypropyloxyphenyl)propane, trimethylolpropane diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, triacryl formal, tetramethylolmethanetetraacrylate, etc., and methacrylic acid compounds Methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, octyl methacrylate,
Ethylhexyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, butoxyethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate,
Hydroxypentyl methacrylate, N/N-dimethylamino methacrylate, N/N-diethylamino methacrylate, tetrahydrofurfuryl methacrylate, methacryloxypropyltrimethoxysilane, allyl methacrylate, trimethylolpropane monomethacrylate, diethylene glycol monomethacrylate, pentaerythritol monomethacrylate, ethylene Glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, 2,2-bis-(4-methacryloxyethoxyphenyl)propane, 2,2-bis -(4-methacryloxydiethoxyphenyl)propane, trimethylolpropane trimethacrylate, etc., butyl crotonate, glycerin monoclonate, vinyl butyrate, vinyl trimethyl acetate, vinyl caproate, vinyl chloroacetate, vinyl lactate, benzoin vinyl acid, divinyl succinate, divinyl phthalate, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-arylmethacrylamide, N-hydroxyethyl-
N-methylmethacrylamide, acrylamide,
N-tert-butylacrylamide, N-methylolacrylamide, N-butoxymethylacrylamide, N-isobutoxymethylacrylamide, diacetone acrylamide, hexyl vinyl ether, ethylhexyl vinyl ether, vinyl tolyl ether, polyvinyl ether of polyhydric alcohol, styrene derivatives such as Styrene, divinylbenzene, allyloxyethanol, diallyl ester of dicarboxylic acid, N-vinyloxazolidone, which has a substituent such as an alkyl group, alkoxy group, halogen, carboxyl group, or allyl group in the ortho and/or para position.
Examples include N-vinylimidazole, N-vinylpyrrolidone, and N-vinylcarbazole, which may be used alone or as a mixture.

The amount of these polymerizable unsaturated compounds used is 10 to 500 parts by weight per 100 parts by weight of the resin content of the polyimide precursor.
parts by weight, preferably 20 to 200 parts by weight. If it is less than 10 parts by weight, curing due to polymerization of the polymerizable unsaturated compound will be insufficient, and if it is more than 500 parts by weight, the heat resistance of the coating film will be reduced due to the influence of residue during post-curing. The amount to be used is desirably determined in consideration of the activity of each polymerizable unsaturated compound and its relationship with the solvent used in the composition, ie, the amount that remains upon drying and can exhibit curing ability.

As the radiation-induced polymerization initiator for these polymerizable unsaturated compounds, various photopolymerization initiators that are generally used as initiators and sensitizers for ultraviolet curable coatings can be used. For example, benzoin, benzoin methyl ether, benzoin ethyl ether,
Benzoin isopropyl ether, benzoin butyl ether, 2-methylbenzoin, benzophenone, Michler's ketone, benzyl, benzyl dimethyl ketal, benzyl diethyl ketal,
Examples include anthraquinone, methylanthraquinone, diacetyl, acetophenone, diphenyl disulfide, and anthracene. The amount of these photoinitiators used is based on the amount of polymerizable unsaturated compounds.
The amount is usually 0.05 to 30 parts by weight, preferably 0.1 to 10 parts by weight per 100 parts by weight. A small amount of conventionally known sensitizing aids such as amines can also be used in combination with these photopolymerization initiators. Further, in order to improve the thermal stability of the composition, it may be effective to coexist with a known thermal polymerization inhibitor.

Specific examples of thermal polymerization inhibitors include paramethoxyphenol, hydroquinone, tert-butylcatechol, pyrogallol, phenothiazine, chloranil, naphthylamine, β-naphthol,
Examples include 2,6-tertiarybutyl-para-cresol, pyridine, nitrobenzene, para-toluidine, methylene blue, etc., and the amount used is usually in the range of 100 parts by weight of the polymerizable unsaturated compound.
The amount is preferably 0.01 to 5 parts by weight.

The photosensitive resin composition thus obtained is applied by an appropriate means and dried. At this time, the aliphatic polyimide precursor obtained from the aliphatic tetracarboxylic acid and diamine, which is the backbone of the composition of the present invention, has very good solubility, and the polymerizable polyimide precursor obtained after the solvent volatilizes during dry coating. Provides a uniform and transparent coating even with saturated compounds. By irradiating active light from a mask with a desired pattern drawn on this coating film, the irradiated area undergoes polymerization of the polymerizable unsaturated compound due to the photopolymerization initiator, and its solubility increases compared to the non-irradiated area. Significant decline. In some cases, irradiation with ionizing radiation such as electron beams or radiation can also produce similar effects. By selecting an appropriate solvent system, a desired resin pattern can be obtained by removing the non-irradiated areas through development.

The resulting resin pattern can be converted into an insulating layer with excellent heat resistance due to the subsequent baking or post-curing, in which the exposed polymerizable unsaturated compound evaporates and the reaction between the amino groups and carboxyl groups of the polyimide precursor further progresses. Therefore, the composition of the present invention is very useful mainly in the field of microfabrication as described above.

The present invention will be explained below with reference to Examples and Reference Examples.

Example 1 39.6 g (0.2 mol) of 4,4'-diaminophenylmethane and ^N. N-dimethylformamide 129.6g
and heat and stir under _N2 gas flow. When the contents were at about 110°C, 46.8 g (0.2 mol) of 1,2,3,4-butanetetracarboxylic acid was added. If the reaction is continued at 110℃, it will have an acid value of 0.907meq/g in about 4 hours (acid value residual rate 24.5%).It has an imide bond in the molecule and a carboxyl group and an amino group at the end of the molecule. A polyimide precursor solution was obtained.

Add 2-ethylhexyl acrylate to this solution.
Add 86.4g and further remove from light.
4.32 g of 651 (manufactured by Ciba Geigy, benzyl dimethyl ketal) was added, mixed with stirring, and filtered through a 1μ filter to obtain a photosensitive resin composition.

This composition was applied onto a glass plate using a spinner at a rotation speed of 3000 rpm, and dried at 90° C. for 10 minutes to obtain a transparent coating film with a thickness of 6.5 μm. A master pattern was placed on this coating, irradiated with 300 mJ/cm ² of ultraviolet light, developed with a mixed solvent of N.N-dimethylformamide and benzene, and rinsed with benzene. A pattern was obtained.

This coating film was heated in air at 350℃ for 2 hours.
Thermogravimetric analysis using a heating rate of 5°C/min showed that no significant weight loss was observed up to 380°C, indicating that the product had good heat resistance.

Example 2 In a flask similar to Example 1, 40.0 g (0.2 mol) of 4,4'-diaminodiphenyl ether and N.
Add 130.2 g of N-dimethylformamide, add 46.8 g (0.2 mol) of 1,2,3,4-butanetetracarboxylic acid in the same manner as in Example 1, and continue the reaction at 110°C to give 1.312 g in about 2 hours. A polyimide precursor solution was obtained which had an acid value of meq/g (acid value residual rate 35.6%) and had an imide bond in the molecule and a carboxyl group and an amino group at the end of the molecule.

Add 2-ethylhexyl acrylate to this solution.
Add 86.8g and further remove from light.
4.34 g of 651 was added, mixed with stirring, and filtered through a 1μ filter to obtain a photosensitive resin composition.

This composition was applied onto a glass plate in the same manner as in Example 1 and dried to obtain a transparent coating film with a thickness of 6.2 μm. When this coating film was irradiated with 300 mJ/cm ² and developed and rinsed in the same manner as in Example 1, a clear pattern was obtained.

This coating film showed no significant weight loss up to 375°C in the evaluation described in Example 1, and had good heat resistance.

Example 3 In a flask similar to Example 1, 39.6 g (0.2 mol) of 4,4'-diaminodiphenylmethane and N.N.
-Add 133.2g of dimethylformamide and proceed as in Example 1 to obtain citalopentanetetracarboxylic acid.
When 49.2 g (0.2 mol) is added and the reaction is continued at 110°C, it has an acid value of 0.994 meq/g in about 4 hours (acid value residual rate 26.2%) and has an imide bond in the molecule. A polyimide precursor solution having a carboxyl group and an amino group at the molecular terminal was obtained.

Add ethyl carbitol acrylate to this solution.
Add 88.8g and further remove from light.
4.44g of 651 was added, mixed with stirring, and filtered through a 1μ filter to obtain a photosensitive resin composition.

This composition was applied onto a glass plate in the same manner as in Example 1 and dried to obtain a transparent coating film with a thickness of 6.3 μm. When this coating film was irradiated with 300 mJ/cm ² and developed and rinsed in the same manner as in Example 1, a clear pattern was obtained.

This coating film showed no significant weight loss up to 380°C in the evaluation described in Example 1, and had good heat resistance.

Reference Example: In a 500 c.c. flask similar to Example 1, 43.6 g (0.2 mol) of pyromellitic dianhydride and N.N-
Add 380.8 g of dimethylformamide and stir on an ice bath under dry N ₂ gas flow. Contents are approximately 5℃
4,4'-diaminodiphenyl ether 40.0g
(0.2 mol) is added little by little while monitoring the degree of heat generation. This addition takes approximately 30 minutes and the temperature of the reactants is
The temperature rose to 15℃. After the addition, the ice bath was removed and stirring was continued for about 2 hours at room temperature to obtain a viscous polyimide acid solution.

Add 2-ethylhexyl acrylate to this solution.
Add 83.6g and further remove from light.
4.18g of 651 was added, mixed with stirring, and filtered through a 1μ filter to obtain a resin composition.

When this composition was applied onto a glass plate in the same manner as in Example 1 and dried, the coating film turned white due to insolubilization.

Furthermore, when ethyl carbitol acrylate was used as the polymerizable unsaturated compound instead of the above-mentioned 2-ethylhexyl acrylate, the coating film was transparent after application and drying, but most of the ethyl carbitol acrylate volatilized. It showed no photosensitivity at all.

Claims (1)

[Claims] 1 Acid value residual rate 40 obtained by reacting aliphatic tetracarboxylic acid and diamine as monomer units
A polymerizable unsaturated compound and a photopolymerization initiator are blended into a solution containing a polyimide precursor that has an imide bond in the molecule and a carboxyl group and an amino group at the end of the molecule, and after drying. The coating film is a novel photosensitive resin composition that substantially allows light to pass through and provides active photosensitivity.