JPH03274557A - Photosensitive resin compostion and formation of pattern - Google Patents

Abstract

PURPOSE:To contrive the improvement in heat resistance and electrical and mechanical characteristics and to facilitate the formation of a relief pattern with high resolution, by forming this composition with the specified amount of a polymer consisting of the specified repeating unit as a main component and the specified total amount of a photo polymerization initiator, photocrosslinker and photo-sensitizer and an organic solvent. CONSTITUTION:The composition is madlup of 100 wt. pts. of polymer consisting of the repeating unit expressed in formula I as the main component, and the sum of 0.1-200 wt. pts. of a photopolymreization initiator, phots crosslinker and photosensitizer and the organic solvent. In formula 1, Ar1 is a tetravalent organic group including at least >= 4C. Ar2 is a divalent organic group incorporating an aromatic ring, R1 is a group containing >=2 photosensitive unsaturated double bonds. The base resin expressed by formula I includes 2 carboxylic acids per one repeating unit and since two carboxylic acids are present thereon, the unexposed part where the photoreaction does not occur, can be developed by a basic water solution. The development by the basic water solution is hard to cause either the swelling or disolution of the exposed part. Thus the heat stability, the improvement of the electrical and mechanical chacharacteristics, the formation of the relief pattern with the high resolution are facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel photosensitive resin composition used for semiconductor devices, multilayer wiring boards, microelectronic devices, etc., and a pattern forming method thereof.

[Conventional technology] Conventionally, surface protection films and interlayer insulating films of semiconductor elements, etc.
Polyimide resins have been used that have poor heat resistance and excellent electrical and mechanical properties, but recently a technology that imparts photosensitivity to polyimide resin itself has attracted attention.

The use of polyimide resins that have been given photosensitivity not only simplifies the pattern creation process compared to polyimide resins that have not been given photosensitivity, but also eliminates the need to use highly toxic etching solutions, making them safer, It is also superior in terms of pollution, and photosensitization of polyimide resin is expected to become an important technology in the future.

As the photosensitive polyimide resin, for example, a polyimide precursor composition to which a photosensitive group is added with an ester group having a structure as shown in the following formula (Japanese Patent Publication No. 55-30207, Japanese Patent Publication No. 55-41422) or the following. A composition in which a compound containing a carbon-carbon double bond and an amino group or a quaternized salt thereof that can be dimerized or polymerized by actinic radiation is added to a polyamic acid having a structure as shown in the formula (for example, JP-A No. 54-145794) and the like are known.

All of these are dissolved in a suitable organic solvent, applied as a varnish, dried, exposed to ultraviolet light through a photomask, developed and rinsed to obtain the desired pattern, and then heat-treated to form a polyimide. It is a coating.

However, ester bond type photosensitive polyimide precursors typified by Japanese Patent Publication No. 55-30207 and Japanese Patent Publication No. 55-41422, as well as Japanese Patent Application Laid-open No. 54-1457,
Since all of the ionic bond type photosensitive polyimide precursors typified by Publication No. 94 use an organic solvent in the developer, swelling of the exposed area is likely to occur during development, and the aspect ratio (resolution/film thickness) It was difficult to obtain a pattern with a high resolution of 1.0 or less.

In particular, when it is necessary to form a 1 μm through hole, such as in an application for an insulating film between the eyebrows, conventional photosensitive polyimide precursors are not necessarily sufficient.

[Problems to be Solved by the Invention] The purpose of the present invention is to improve the above-mentioned drawbacks of the conventional photosensitive polyimide resin, and to create a high-resolution relief pattern with excellent heat resistance, electrical and mechanical properties. An object of the present invention is to provide a photosensitive resin composition that can be easily formed and a method for forming a pattern.

[Means for Solving the Problem] The present invention provides the following features: (1) (A) - Tsuriage CI) (In the formula, Ar is a tetravalent organic group containing at least 4 or more carbon atoms, a divalent organic group containing a group ring,
R represents a group having two or more photosensitive unsaturated double bonds. ) 100 parts by weight of a polymer whose main component is a repeating unit represented by (B) a photopolymerization initiator, a photocrosslinking agent, and a sensitizer in a total amount of 0.
A photosensitive resin composition comprising 1 to 200 parts by weight and an organic solvent.

(2) A pattern forming method using the photosensitive resin composition described above, which is characterized in that a basic aqueous solution is used when applying the photosensitive resin composition onto a substrate, drying it, and then irradiating it with ultraviolet rays or the like to develop the unexposed areas.

[Function] The structure of the base resin of the photosensitive resin composition of the present invention is shown in the general formula CI), and a photopolymerization initiator, a photocrosslinking agent, a sensitizer, and an organic solvent are added thereto as additives. It is made into a photosensitive resin composition. One of the major reasons for the high-resolution relief pattern obtained in the present invention is that a basic aqueous solution is used as the developer. In the case of the conventional photosensitive polyimide precursor mentioned above, one type or a combination of two or more organic solvents are used in the developer, but in either case, swelling or dissolution occurs in the exposed area, resulting in high It was difficult to obtain patterns of resolution. - The base resin of the present invention shown in the binding margin (I) has two carboxylic acids per repeating unit, and the presence of these two carboxylic acids causes the unexposed portions that are not photoreacted to be It became possible to develop with a basic aqueous solution. In development with a basic aqueous solution, neither swelling nor dissolution of the exposed area occurs easily, making it possible to form a relief pattern with high resolution.

-a of the polymer represented by repeating units of formula CI)
Examples of preferable examples are listed below, but the invention is not particularly limited to these. Moreover, two or more types may be used in combination.

Examples of preferable Ar2 include (However, Xl,
t -0-, -6-, -5O2-, -CO-, -CH
2-.

C) represents one type selected from 13), but is not limited to these in any way.

The R group of the present invention is a group having two or more photosensitive unsaturated double bonds, and preferable examples include the following structures.

□ CH3 CH3 etc.

Furthermore, in the polymer of the present invention, units in which the R unit represented by the repeating unit CI) is obtained using an aromatic diamine that does not have two or more photosensitive unsaturated double bonds also have an adverse effect on photosensitivity. It can be used as long as it does not affect For example, units consisting of aromatic diamines and aromatic tetracarboxylic dianhydrides that do not have photosensitive unsaturated double bonds, such as 4,4'-diaminodiphenyl ether and paraphenylene diamine, and 3,5-diamino- From aromatic diamines and aromatic tetracarboxylic dianhydrides containing one photosensitive unsaturated double bond, such as benzoic acid ethyl cinnamate, 3,5-diamino (2'-methacryloyloxyethyl) benzoate, etc. Examples include units of

The polymer represented by the repeating unit of general formula CI) is synthesized by a polycondensation reaction of tetracarboxylic dianhydride or its derivatives (including ester derivatives and acid halide conductors) and an aromatic diamine compound having a photosensitive group.

The photosensitive resin composition of the present invention requires addition of a photopolymerization initiator, a photocrosslinking agent, or a sensitizer.

As an initiator used in the photosensitive resin composition, 2.2-
Dimethoxy-2-phenyl-acetophenone, l-hydroxy-cyclohexyl-phenylketone, 2-methyl-14-(methylthio)phenyl]-2-morpholino-1-propane, 3.3', 4.4'-tetra −(t
-butylperoxycarbonyl)benzophenone, benzyl, benzoin-isopropyl ether, benzoin-isobutyl ether, 4,4'-dimethoxybenzyl, 1,4-dibenzoylbenzene, 4-benzoylbiphenyl, 2-benzoylnaphthalene, methyl-〇- Benzoylbenzoate, 2,2'-bis(Q-chlorophenyl)-4,4', 5,5'-tetraphenyl-1,
2'-biimidazole, 10-butyl-2-chloroacridone, ethyl-4-dimethylaminobenzoate, dibenzoylmethane, 2,4-diethylthioxanthone,
3゜3-dimethyl-4-methoxy-benzophenone, 2
-Hydroxy-2-methyl-1-phenylpropane-1
-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, ■-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-phenyl -1,2-butanedione-
2-(0-methoxycarbonyl)oxime, 1-phenyl-propanebutanedione-2-(O-benzoyl)oxime, 1,2-diphenyl-ethanedione-1-(o
-benzoyl)oxime, 1,3-diphenyl-propanetrione-2-(O-benzoyl)oxime, 1-phenyl-3-ethoxy-propanetrione-2-(o-
bezoyl) oxime, oxacylone compounds, etc. Of course, two or more types may be used in combination.

The photocrosslinking agent used in the present invention is an acrylic compound having a molecular weight of 500 or less and having two or more acrylic or methacrylic groups in one molecule. Monofunctional acrylates having one acrylic group in one molecule are not preferred because they cannot be photopatterned because a crosslinked structure cannot be obtained even when irradiated with light. Moreover, if the molecular weight is 500 or more, it is not only difficult to uniformly dissolve it, but also it remains in the pattern without being dissipated by heat even during heat treatment for thermosetting, resulting in a marked decrease in heat resistance, which is undesirable. Examples include ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, trimethylolgloban triacrylate, trimethylolpropane tosomethacrylate, bisphenol Examples include, but are not limited to, A dimethacrylate. Of course, there is no problem in using two or more types together.

Sensitizers used in the present invention include benzophenone,
Acetophenone, anthrone, p,p'-tetramethyldiaminobenzophenone (Michler's ketone), phenanthrene, 2-nitrofluorene, 5-nitroacenaphthene, benzoquinone, doacetyl-p-nitroaniline,
p-Nitroaniline, 2-ethylanthraquinone, 2-
Tertiary-butylanthraquinone, N-acetyl-4
-Nitro-1-naphthylamine, biclamide, 1,2-
Benzanthraquinone, 3-methyl-1,3-diaza-
1,9-benzanthrone, p.

p'-Tetraethyldiaminobenzophenone, 2-chloro-4-nitroaniline, dibenzalacetone, l.

2-naphthoquinone, 2,5-bis-(4'-diethylaminobenzal)-cyclopentane, 2,6-bis-(4
'-diethylaminobenzal)-cyclohexanone, 2
,6-bis-(4'-dimethylaminobenzal)-4-
Methyl-cyclohexanone, 2,6-bis-(4'-diethylaminobenzal)-4-methyl-cyclohexanone, 4,4'-bis-(dimethylamino)-chalcone,
4.4'-bis-(diethylamino)-chalcone, p-
Dimethylaminobenzylidene indanone, 1,3-bis-(4'-dimethylaminobenzal)-acetone, 1.
Examples include, but are not limited to, 3-bis-(4'-diethylaminobenzal)-acetone, N-phenyl-jetanolamine, Nph lyludiethylamine, and styryl compounds. Of course, it is also possible to use two or more types in combination.

The total amount of the photopolymerization initiator, photocrosslinking agent, and sensitizer added is 1.
It is preferably 0.1 to 2 parts by weight based on the weight of the sphere. The appropriate amount of each addition is determined depending on the combination used, but if the total is less than 0.1 part by weight, a sufficient photocrosslinked product will not be obtained and will dissolve during development, which is not preferred.

Moreover, if the total amount added exceeds 200 parts by weight, the properties of the film after heat treatment and curing will deteriorate, which is not preferable.

Furthermore, for the photosensitive resin composition of the present invention, a polymerization inhibitor,
It is also possible to appropriately add various additives such as a flattening agent, an adhesion improver, and a dye.

The photosensitive resin composition according to the present invention is used in the form of a solution in which the above components are dissolved in a suitable organic solvent. The solvent in this case is preferably an aprotic polar solvent. Typical solvents of this type are N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, N,N-di,methylmethoxyacetamide, dimethyl Examples include sulfoxide, hexamethylphosphoamide, dimethylsulfolane, tetramethylene sulfone, dimethyltetramethylene sulfone, γ-butyl lactone, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and the like. These may be used alone or in a mixed system.

In addition, solvents such as benzene, benzonitrile, dioxane, xylene, toluene, and cyclohexanone may be used in combination as solvents for the purpose of improving coating properties, as long as they do not adversely affect the dissolution of the photosensitive resin composition. It is possible to use

The photosensitive resin composition according to the present invention can be patterned using ordinary microfabrication techniques. For applying the present composition to the support substrate, appropriate methods can be selected, such as spin coating using a spinner or the like, dipping, and spraying. The coating film thickness can be adjusted by adjusting the coating equipment used, coating conditions, solid content concentration of the composition, etc.

After applying the composition to a desired thickness on a support substrate, prebaking is performed for drying purposes. Prebaking can normally be carried out using a hot plate or oven, but excessive heating is not preferred since it may cause thermal polymerization of unsaturated double bonds, making it impossible to perform development quickly in the subsequent development step. do not have.

It is desirable to use the minimum baking conditions necessary for drying. After the film has dried, it is irradiated with ultraviolet rays through a photomask, and then the unexposed areas are dissolved and removed using a developer. In this case, it is preferable to use a basic aqueous solution as the developing solution in order to form a pattern with poor resolution.

Conventional photosensitive compositions using photosensitive boimide precursors use organic solvents in the developer, but in this case, the exposed areas tend to swell and dissolve during development, and the aspect ratio (resolution/film thickness) It was difficult to obtain a high resolution of 1.0 or less. When the basic aqueous solution of the present invention is used as a developer, neither swelling nor dissolution of exposed areas occurs easily, and it is possible to form a high-resolution pattern with an aspect ratio of 1.0 or less. The basic aqueous solution used in the present invention is an inorganic basic compound, such as sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium phosphate, sodium hydrogen phosphate, ammonium phosphate, ammonium hydrogen phosphate, etc. , aqueous solutions of sodium metasilicate, sodium bicarbonate, ammonia, etc., or aqueous solutions of organic basic compounds such as tetramethylammonium hydroxide, β-hydroxyethyl-trimethylammonium hydroxide, piperidine, triethanolamine, etc. These can be used alone or in a mixture of two or more, and a surfactant or the like can also be added if necessary. Note that the concentration of the developer can be appropriately selected in order to obtain a desired development time.

Furthermore, in some cases, an organic solvent such as methanol, ethanol, isopropanol, or the like may be added by filtration for the purpose of adjusting the development speed in an amount that does not cause a decrease in resolution.

The relief pattern formed by development is then washed with a rinsing solution to completely remove the developer.

It is desirable to use water as the rinsing liquid because of its affinity with the developer.

The pattern formed by the above treatment is then subjected to heat curing treatment in order to completely scatter the imidization, photosensitizer, and various additives. The conditions for heat curing treatment are 1.
By using a temperature selected from the range of 50° C. to 4° C. and using an atmosphere of air or an inert gas such as nitrogen, a polymer pattern with excellent heat resistance can be obtained.

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

Example 1 36.24 g of 3,5-diamino-benzoic acid ((1,3-methacryloyl)glyceryl) ester was placed in a four-necked separable flask equipped with a thermometer, stirrer, raw material inlet, and dry air inlet. , N-methyl-2-pyrrolidone 200
g and stir to dissolve the contents. After dissolution, the flask was cooled with water, and 31.02 g of 4,4'-oxycyphthalic dianhydride was gradually added, keeping the temperature of the system at 20°C. After the addition is complete, stirring is continued for 8 hours at 20°C to complete the reaction. At this time, dry air is introduced into the reaction system from the time the diamine compound is dissolved until the end of the reaction. The obtained photosensitive polyimide precursor solution was a brown transparent viscous liquid, and no gel-like substance was observed. 4.0 g of N-phenyl-jetanolamine in the above polyimide precursor solution.
, 1-phenyl-1,2-butanedione-2-(0-
2.0 g of methoxycarbonyl oxime and 0.067 g of hydroquinone were added, coated on a silicon wafer, and prebaked at 70° C. for 60 minutes to obtain a film with a thickness of about 20 μm. This coating film was irradiated with ultraviolet rays using a 500 W high pressure mercury lamp through a photomask having a test pattern.

The intensity of ultraviolet rays on the exposed surface is 14 m at a wavelength of 365 nm.
W/crn'. After exposure, development was performed using a developer containing a 2.38% aqueous solution of tetramethylammonium hydroxide, followed by rinsing with pure water to obtain a pattern. The film thickness after development was measured, and the sensitivity was 50 iJ/cm when the irradiation amount when the film thickness after development became 1/2 of the coating film thickness.

The resolution was approximately lOμ. Next, this pattern was heat-treated in air at 150° C., 250° C., and 350° C. for 30 minutes each, and the pattern was good with no blurring observed. On the other hand, when a tensile test was conducted on a coating film that had been heat-treated up to 350°C, the strength was 10 kg/mm.
2. The elongation rate was good at 7%.

Examples 2 to 5 The same operations as in Example 1 were performed except for the reaction components used in polyimide precursor synthesis and the developer composition used in patterning, and the results shown in Table 1 were obtained. The amounts of the sensitizer, initiator, and polymerization inhibitor added were adjusted to be exactly the same as the ratio of each component added to the polyimide precursor in Example 1.

Comparative Example 1 In a separable flask similar to Example 1, 20.02 g of 4,4'-diaminodiphenyl ether and N-methyl-
200 g of 2-pyrrolidone was added and dissolved. After dissolution, the flask is cooled, 21.81 g of pyromellitic anhydride is gradually added, and the system temperature is maintained at 20° C. and stirred for 8 hours to complete the reaction. At this time, dry nitrogen is flushed through the system to prevent moisture from entering. 0.80 g of Michler's ketone and 7.0 g of dimethylaminoethyl methacrylate were added to 50 g of the obtained polyamic acid solution to prepare a photosensitive polyimide precursor solution.

This solution was applied onto a silicon wafer and prebaked at 70°C for 60 minutes to obtain a film about 20 μm thick. This coating film was irradiated with ultraviolet rays through a photomask in the same manner as in Example 1. After exposure, the pattern was developed with a developer consisting of a mixed solution of N,N-dimethylacetamide/methanol (60/40=W/W), and further rinsed with isopropanol to obtain a pattern. The sensitivity was 50 mJ/crrr, but the resolution was 30 μm and the aspect ratio was at a low level of about 3. Next, this pattern was heated at 150°C, 250°C,
When heat treatment was performed in air at 350° C. for 30 minutes each, no blurring of the pattern was observed. The tensile properties of the coating film were good, with a strength of 12 kg/2 and an elongation of 10%.

Comparative Example 2 A compound [1,4-dicarboxy-2,5-(2 47.83
g and 4,4'-diaminodiphenyl ether 20.02
After dissolving in 200 g of anhydrous γ-butyrolactone under a stream of dry nitrogen, 10 g of pyridine was added.

Furthermore, 12.25 g of dicyclohexylcarbodiimide (25 g) was gradually added to the system while cooling in a water bath.

After the addition was complete, stirring was continued for another 2 hours at 20°C, and then
After adding 0 g of methanol and stirring for 30 minutes, the reaction solution was precipitated in a large amount of methanol, and the precipitated polymer was collected by filtration. This was dried day and night under reduced pressure at room temperature to obtain a polymer powder. 30g of this polymer, 0 Michler ketone
．． 9g.

70 g of pentaerythritol thioglycolate
g of N-methyl-2-pyrrolidone to obtain a photosensitive polyimide precursor solution. Using this solution, a silicon wafer was coated and prebaked in the same manner as in Comparative Example 1 to obtain a film with a thickness of about 20 μm. After exposing to ultraviolet light through a photomask, N-methyl-2-pyrrolidone/xylene ( A pattern was obtained by developing with a mixed solution (80/20=W/W) and rinsing with isopropanol. Sensitivity is 40
mJ/ca+2, but the resolution was 30 μm and the aspect ratio was at a low level of about 3. Next, this pattern was heated at 150°C and 250°C for 30 minutes each in an air atmosphere, and then heat-treated at 350°C and 1400°C for 30 minutes each in a nitrogen atmosphere, and no blurring of the pattern was observed. The tensile strength of the film is 3.5 kg/
mm2, and the elongation rate was 1.0%, which was very low.

Comparative Example 3.4 The same method as in Example 1 was carried out except for the diamine component, acid dianhydride component and developer composition shown in Table 1, and the results shown in Table 1 were obtained regarding photosensitive properties and tensile properties. Ta.

[Effects of the Invention] As is clear from the results in Table 1, in Examples 2 to 5, patterns with high resolution (aspect ratio of 1.0 or less) of less than 10μ were all obtained in terms of photosensitive characteristics, especially resolution. Good results have been obtained in terms of mechanical properties. On the other hand, although good tensile properties were obtained in Comparative Example 1, the resolution was at a low level of about 3 in terms of aspect ratio because the developing solution used was an organic solvent.

In Comparative Example 2, as in Comparative Example 1, only a low-resolution pattern with an aspect ratio of 3 was obtained because the developer was an organic solvent-based developer. Further, since high-temperature heating of 400° C. is required for complete imidization, some of the polymers are thermally degraded, resulting in poor mechanical properties and poor flexibility.

In Comparative Example 3, development was also carried out using an organic solvent, so only a low resolution pattern with an aspect ratio of 2.5 was obtained.

In Comparative Example 4, although an organic alkaline aqueous solution is used as the developer, the photosensitive group is monofunctional and the polymerization and dimerization reactions upon exposure to ultraviolet rays do not take place sufficiently, so the sensitivity itself is insufficient and is not good. Couldn't get a pattern.

Therefore, from the above results, the photosensitive resin composition of the present invention can easily form a high-resolution relief pattern with excellent heat resistance, electrical and mechanical properties, and the method of the present invention can be used to easily form a high-resolution relief pattern. It can be seen that when the pattern is formed, good photosensitive properties as well as excellent tensile properties can be obtained.

Claims (2)

[Claims] (1) (A) General formula [I] ▲Mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[I] (In the formula, Ar_1 is a tetravalent organic group containing at least 4 or more carbons, Ar_2 is an aromatic A divalent organic group containing a group ring, R
_1 represents a group having two or more photosensitive unsaturated double bonds. ) 100 parts by weight of a polymer whose main component is a repeating unit represented by (B) a photopolymerization initiator, a photocrosslinking agent, and a sensitizer in a total amount of 0.
A photosensitive resin composition comprising 1 to 200 parts by weight and an organic solvent. (2) A pattern forming method using the above-mentioned photosensitive resin composition, which comprises using a basic aqueous solution when applying the photosensitive resin composition onto a substrate, drying it, and then irradiating it with ultraviolet rays or the like to develop the unexposed areas.