JPH04240856A - Pattern forming method using photosensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain the photosensitive resin composition capable of forming a relief pattern high in resolution and low in elastic modulus and superior in heat resistance and electric characteristics by incorporating a polymer comprising repeating units of tetracarboxylic acid dihydrate or its derivative having siloxane group as main components. CONSTITUTION:This photosensitive resin composition comprises (A) 100 pts.wt. of the polymer comprising repeating units represented by general formula I, and (B) 0.1-200 pts.wt. of a photopolymerization initiator, a photocross-linking agent, and a sensitizer, and an organic solvent, and a base plate is coated with the composition, dried, exposed, and then, the unexposed area is developed with an aqueous basic solution. Since the resin of formula I has 2 carboxylic groups per each repeating unit, the unexposed area can be developed with the basic solution, and at that time, this unexposed area is reduced in tendency to be dissolved or swelled by the basic solution, and accordingly, the relief pattern high in resolution is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming patterns using a novel photosensitive resin composition used for semiconductor devices, multilayer wiring boards, microelectronic devices, etc.

0002

[Prior Art] Conventionally, polyimide resins, which have excellent heat resistance and excellent electrical and mechanical properties, have been used for surface protection films and interlayer insulation films of semiconductor devices. Technology that imparts photosensitivity to resin itself has been attracting attention. Using polyimide resins that have been given these photosensitizers 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 even more important technology in the future.

[0003] As a photosensitive polyimide resin, for example, the following formula is used.

0004

[Case 2]

A polyimide precursor composition having a photosensitive group provided with an ester group having the structure shown in
30207, Japanese Patent Publication No. 55-41422) or the following formula

[0006]

[Chemical formula 3]

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 (Japanese Patent Publication No. 145794/1983) are known.

Each of these is dissolved in a suitable organic solvent, applied in the form of a varnish, dried, irradiated with ultraviolet light through a photomask, developed and rinsed to obtain a desired pattern, and further heat-treated. This makes it a polyimide coating.

However, when such conventional photosensitization techniques are applied to a polyimide resin with a low elastic modulus in which a siloxane group is introduced into the polyimide resin component, it is difficult to pattern even when irradiated with ultraviolet rays, or the sensitivity is extremely low. The exposure equipment commonly used in the semiconductor industry was insufficient for processing. Furthermore, ester bond type photosensitive polyimide precursors typified by Japanese Patent Publication No. 55-30207 and Japanese Patent Publication No. 55-41422, and Japanese Patent Application Laid-open No. 54-1989
Since all of the ionic bond type photosensitive polyimide precursors typified by Publication No. 145794 use an organic solvent in the developer, swelling of the exposed area tends 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. Especially when it is necessary to form 1 μm through holes such as for interlayer insulation film applications,
Conventional photosensitive polyimide precursors have not always been sufficient.

0010

[Problems to be Solved by the Invention] It is an object of the present invention to improve the drawbacks of the conventional photosensitive polyimide resins mentioned above, and to develop a high-resolution resin with a low elastic modulus, excellent heat resistance, and electrical properties. An object of the present invention is to provide a method for forming a pattern using a photosensitive resin composition that can easily form a relief pattern.

[0011]

[Means for Solving the Problems] The present invention provides (A) a polymer 1 whose main component is a repeating unit represented by the general formula [I].
0.00 parts by weight, (B) 0.1 to 200 parts by weight of a photopolymerization initiator, a photocrosslinking agent, a sensitizer in total, and an organic solvent is coated on a substrate, dried, and after exposure. , is a pattern forming method characterized by developing unexposed areas with a basic aqueous solution.

0012

[C4]

[0013]

[Function] The structure of the base resin of the photosensitive resin composition of the present invention is shown in the general formula [I]. In addition, it is 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. General formula [I]
The base resin of the present invention shown in 1 has two carboxylic acids per repeating unit, and due to the presence of these two carboxylic acids, the unexposed and non-photoreacted areas are developed with a basic aqueous solution. It became possible. 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.

Preferred examples of Ar1 in the polymer represented by the repeating unit of general formula [I] are:

0
015]

[C5]

[0016] etc., but are not particularly limited to these. Moreover, two or more types may be used in combination. A
An example of what is preferable as r2 is

[0017]

[C6]

[0018] etc., but the invention is not limited to these in any way. R1 in the present invention is a group having two or more photosensitive unsaturated double bonds, and preferred examples include the following structures.

[0019]

[C7]

[0020] etc.

R2 and R3 represent a monovalent aliphatic group or an aromatic group, and may be the same or different. n is an integer from 1 to 100.

The siloxane-containing acid dianhydride has the effect of lowering the elastic modulus of the polyimide coating. The effect is not exhibited when the amount is less than 5 mol% in the tetracarboxylic dianhydride, so it is desirable that the amount is 5 mol% or more. Moreover, if it exceeds 60%, the heat resistance will drop significantly and the characteristics inherent to polyimide resins will no longer be obtained, which is not preferable. The degree of polymerization n of the siloxane must be 1 to 100. If n is less than 1, the effect of lowering the elastic modulus cannot be obtained, and acid dianhydrides containing long chain polysiloxanes exceeding 100 cannot be used. If used, it becomes difficult for the reaction with the diamine to proceed quantitatively, and it remains as an unreacted substance, which not only does not increase the molecular weight but also reduces flexibility and makes cracks more likely to occur, which is not preferable.

In addition, in the polymer of the present invention, units obtained by using an aromatic diamine in which R1 represented by the repeating unit [I] does not have two or more photosensitive unsaturated double bonds are also photosensitive. It can be used as long as it does not adversely affect sex. For example, units consisting of aromatic diamines and aromatic tetracarboxylic dianhydrides that do not have a photosensitive unsaturated double bond, such as 4,4'-diaminodiphenyl ether and paraphenylenediamine, and 3,5-diamino- Ethyl benzoate cinnamate, 3,5-diamino(2
Examples include units consisting of an aromatic diamine containing one photosensitive unsaturated double bond and an aromatic tetracarboxylic dianhydride, such as '-methacryloyloxyethyl) benzoate.

Furthermore, in the polymer of the present invention, units obtained using an aromatic tetracarboxylic dianhydride that does not have a siloxane component can also be used as long as they do not affect the elastic modulus. . Examples include units consisting of an aromatic tetracarboxylic acid and an aromatic diamine such as oxydiphthalic dianhydride, benzophenone tetracarboxylic dianhydride, and pyromellitic dianhydride.

The polymer represented by the repeating unit of general formula [I] is a condensation polymerization of a siloxane-containing tetracarboxylic dianhydride or its derivatives (including ester derivatives and acid halide derivatives) and an aromatic diamine compound having a photosensitive group. Synthesized by reaction.

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

Initiators used in the photosensitive resin composition include 2,2-dimethoxy-2-phenyl-acetophenone, 1-hydroxy-cyclohexyl-phenylkene, 2-methyl-[4-(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-o-benzoylbenzoate, 2,2'-bis(o-
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-phenylpropan-1-one, 1-(4-isopropylphenyl)-
2-hydroxy-2-methylpropan-1-one, 1-
(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-phenyl-1,2-butanedione-2-(o-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
Examples include -(o-bezoyl)oxime and oxazolone compounds. 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 methacryl groups in one molecule. Monofunctional acrylates, which have one acrylic group in one molecule, cannot be photopatterned because a crosslinked structure cannot be obtained even when irradiated with light.
Undesirable. 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. For example:
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-hexane Diol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, bisphenol A
Examples include, but are not limited to, 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, N-acetyl-p-nitroaniline, p-nitroaniline, 2-ethylanthraquinone, 2-tert-butylanthraquinone, N
-acetyl-4-nitro-1-naphthylamine, picramide, 1,2-benzanthraquinone, 3-methyl-1
,3-diaza-1,9-benzanthrone, p,p'-
Tetraethyldiaminobenzophenone, 2-chloro-4
-nitroaniline, dibenzalacetone, 1,2-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-dimethylaminobenzylideneindanone, 1,3-bis-(4'
-dimethylaminobenzal)-acetone, 1,3-bis-(4'-diethylaminobenzal)-acetone, N-
Examples include phenyl-diethanolamine, N-p-tolyl-diethylamine, and styryl compounds, but are not particularly limited thereto. 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 0.1 to 200 parts by weight per 100 parts by weight of the polymer whose main component is the repeating unit represented by the general formula [I]. part is preferred. The appropriate amount of each additive is determined depending on the combination used, but if the total is less than 0.1 parts 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, various additives such as a polymerization inhibitor, a surface smoothing agent, an adhesion improver, and a dye can be appropriately added to the photosensitive resin composition of the present invention.

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-dimethylmethoxyacetamide,
dimethyl sulfoxide, hexamethylphosphoamide,
Examples include 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 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 an open oven, but excessive heating is not recommended 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. As the developing solution used in this case, it is preferable to use a basic aqueous solution in order to form a pattern with excellent resolution. Conventional photosensitive compositions using photosensitive polyimide 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/
It was difficult to obtain a high resolution of 1.0 or less (film thickness). 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,
Aqueous solutions such as potassium hydroxide, lithium hydroxide, sodium phosphate, sodium hydrogen phosphate, ammonium phosphate, ammonium hydrogen phosphate, sodium metasilicate, sodium bicarbonate, ammonia, or organic basic compounds such as tetramethylammonium hydroxide, β -Hydroxyethyl-trimethylammonium hydroxide, piperidine, triethanolamine, etc., in an aqueous solution. 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, or isopropanol may be added in an amount that does not cause a decrease in resolution for the purpose of adjusting the development speed.

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 to completely scatter the imidization, photosensitizer, and various additives. A polymer pattern with excellent heat resistance can be obtained by using a temperature selected from the range of 150°C to 400°C as the conditions for heat curing treatment, and using the processing atmosphere in air or an inert gas such as nitrogen. It will be done. The present invention will be explained below with reference to Examples.

[0036]

[Example] (Example 1) Thermometer, stirrer, raw material inlet,
36.24 g of 3,5-diamino-benzoic acid [(1,3-methacryloyl)glyceryl] ester, N-methyl-
Add 200 g of 2-pyrrolidone and stir to dissolve the contents. After dissolution, the flask was cooled with water, and 15.27 g of pyromellitic dianhydride and the following formula

[0037]

[Chemical formula 8]

25.01 g of the acid dianhydride shown below was gradually added, and the temperature of the system was maintained at 20°C. After the addition was completed, stirring was 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.

[0039] 4.0 g of N-phenyl-diethanolamine and 1-phenyl-1,2
-butanedione-2-(0-methoxycarbonyl)oxime 2.0g and hydroquinone 0.067g were added,
It was 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 light on the exposed surface was 14 mW/cm2 at a wavelength of 365 nm. 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 65 mJ/cm 2 when the radiation dose when the film thickness after development became 1/2 of the coating film thickness. The resolution was about 12 μm. Next, this pattern was heated to 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 and the result was good. On the other hand 3
When a tensile test was conducted on a coating film that had been heat-treated up to 50℃, the strength was 7.0kg/mm2 and the elongation rate was 20.
%, which was good. Further, the elastic modulus showed a good value of 115 kg/mm2.

(Examples 2 to 5) The same operations as in Example 1 were carried out except for the reaction components used for polyimide precursor synthesis, 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.

[0041]

[Table 1]

(Comparative Example 1) A photosensitive polyimide precursor represented by the following structural formula was added to an N-methyl-2-pyrrolidone solution in exactly the same ratio as the amount of each component added to the polyimide precursor in Example 1. A sensitizer, an initiator, and a polymerization inhibitor were added.

[0043]

[Chemical formula 9]

[0044] Regarding this photosensitive resin composition, Example 1
I tried to form a pattern using exactly the same treatment as above, but
It cannot be developed if an aqueous solution of tetramethylammonium hydroxide is used as the developer, and development is possible only by using an organic solvent such as a 1:1 mixed solvent of N-methyl-2-pyrrolidone and xylene. Met.

(Comparative Example 2) A photosensitive polyimide precursor represented by the following structural formula was added to an N-methyl-2-pyrrolidone solution in exactly the same ratio as the amount of each component added to the polyimide precursor in Example 1. A sensitizer, an initiator, and a polymerization inhibitor were added.

[0046]

[Chemical formula 10]

[0047] Regarding this photosensitive resin composition, Example 1
I tried to form a pattern using exactly the same treatment as above, but
When a tetramethylammonium hydroxide aqueous solution was used as the developer, no pattern could be obtained.

(Comparative Examples 3 to 5) The results shown in Table 1 were obtained in exactly the same manner as in Example 1 except for the reaction components used for polyimide precursor synthesis. The ratios of the sensitizer, initiator, and polymerization inhibitor added were adjusted to be the same as in Example 1.

[0049]

Effects of the Invention In Examples 1 to 5, photosensitive resin compositions with excellent resolution and low elastic modulus after heat treatment were obtained, and good patterns could be formed. On the other hand, Comparative Examples 1-2
However, it was not possible to develop with a basic aqueous solution. In Comparative Example 3, the degree of polymerization of siloxane in the siloxane-containing tetracarboxylic dianhydride was too high, so a cured product with sufficient strength could not be obtained. In Comparative Example 4, the content of 3,5'-diaminobenzoic acid [(1,3'-methacryloyl)glyceryl] ester, which is a diamine having a photosensitive group, was not sufficient, so the exposure amount was not more than 1000 mJ/cm2. No pattern is obtained and the resolution is 5
It was as low as 0 μm or more. In Comparative Example 5, since the siloxane-containing tetracarboxylic dianhydride was not used, the elastic modulus after heat treatment was as high as 380 kg/mm2.

Therefore, from the above results, it can be seen that the pattern formed according to the present invention has good photosensitive characteristics and a low elastic modulus.

Claims (1)

[Claims] Claim 1: (A) 100 parts by weight of a polymer whose main component is a repeating unit represented by general formula [I], and (B) 0.1 to 200 parts by weight of a photopolymerization initiator, a photocrosslinking agent, and a sensitizer. Applying a photosensitive resin composition consisting of parts by weight and an organic solvent to a substrate,
A pattern forming method characterized by developing unexposed areas with a basic aqueous solution after drying and exposure. [Chemical formula 1]