JPH07140673A - Method for forming patterned polyimide coating film on substrate - Google Patents

Abstract

PURPOSE:To provide a method for forming a patterned polyimide coating film on a substrate. CONSTITUTION:In the method for forming the patterned polyimide coating film by forming a coating film by applying a photocrosslinkable polymer composition obtained by modifying a polyimide precursor with a compound having a photosensitive group on the substrate, imagewisely exposing, developing and heating the hardened coating film of the exposed part to convert to a polyimide resin coating film, a solvent mixture of non-protic polar solvent with cycloparaffin based hydrocarbon or cycloparaffin based hydrocarbon compound is used as the developer in developing process.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a protective film, an insulating film, an interlayer insulating film, a passivation film, a recording element, a plate making in the semiconductor manufacturing industry, microelectronics industry, photolithography, imaging field including hologram and laser recording. It relates to a method for producing a material or the like from a photocrosslinkable polymer composition obtained by modifying a polyimide precursor with a compound having a photosensitive group. More specifically,
It relates to a method for obtaining a predetermined pattern on a substrate by imagewise exposing a coating film obtained by applying the above-mentioned photocrosslinkable polymer composition onto the substrate and removing the unexposed portion.

[0002]

2. Description of the Related Art In recent years, in the semiconductor manufacturing industry and the microelectronics industry, a resin having a heterocyclic group in its molecular structure, such as a polyimide resin having high heat resistance and excellent electrical and mechanical properties, is an insulating film for integrated devices. It has also been used as a passivation film and as an interlayer insulating film of a high-density mounting substrate.

When an insulating film is formed of this resin, it may be necessary to form a circuit between a metal or a conductor which is a lower layer of the insulating film and another electronic element or device. In addition, when forming an interlayer insulating film with this resin, it is often necessary to provide a conductive path between the upper and lower layers to establish conduction. Therefore, a via hole is provided in the resin film and the upper and lower layers are connected via this via hole. It will be connected by a conductor. Then, such an insulating film or an interlayer insulating film is formed using a photosensitive polyimide precursor composition having excellent processability, and the insulating film or the interlayer insulating film has a desired patterned shape by a pattern forming method. Things have come to be done. The pattern forming method using the above-mentioned photosensitive polyimide precursor composition is performed, for example, in the following steps.

Coating: A polyimide precursor composition varnish is coated on a substrate. Baking: The material in the above composition varnish is evaporated to form a coating film. Exposure: Exposure is performed using an ultraviolet exposure device and a predetermined photomask. Development: A non-crosslinked portion is dissolved and removed with a developing solution and washed with a rinse solution to obtain a pattern. Cure: It is converted into a polyimide resin by heating.

Further, in the fields of photolithography and imaging, optical recording materials such as plate-making materials obtained by using a photosensitive polyimide precursor composition have been attracting attention due to their excellent properties such as mechanical strength. Then, the coating film of such a photosensitive polyimide precursor is subjected to imagewise exposure, and as a developing solution when the non-crosslinked portion is dissolved and removed by a developing solution, for example, N-methyl-2-pyrrolidone, γ-butyrolactone, xylene or alcohol is used. , A mixed solution of ester and water is used.

[0006]

However, when forming a polyimide pattern using a polyimide precursor,
Excellent in resolution and residual film characteristics. Prevents the generation of residues without fail, and considers the cost of development and rinsing liquid consumption. Good solvents and aromatics for polyimide precursors such as N-methyl-2-pyrrolidone and γ-butyrolactone. hydrocarbon,
Mixed solvents with poor solvents such as alcohols and esters are widely used as developers and rinses.

At the same time, various standards and regulations in consideration of environmental protection and effects on the human body have been expanded, and as a result, aromatic hydrocarbon compounds have come to be regulated in recent years, and as a developing solution or a rinsing solution as described above. It is expected that it cannot be used.

Therefore, as a poor solvent which replaces the aromatic hydrocarbon compound, it exhibits substantially the same resolution and developing ability as the residual film characteristics when an aromatic hydrocarbon compound is used, and in a series of steps of forming a polyimide pattern. There is a demand for a solvent that can be used as a developing solution under the same process control (for example, developing time) as when an aromatic hydrocarbon compound is used. Here, it is possible to obtain equivalent properties without being inferior or superior to aromatic hydrocarbon compounds which are widely used from the cost advantage, by starting by applying the above-mentioned polyimide precursor composition. It is very important in that the productivity of the whole process can be maintained without changing the production line that carries out a series of processes for curing and forming a pattern made of a polyimide resin.

[0009]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems of the prior art, and as a result, they are obtained by applying a photosensitive polyimide precursor composition onto a substrate. We developed a developing and rinsing solution that can perform imagewise exposure on a film and shorten the development time when developing it and at the same time perform pattern formation with high resolution and residual film rate without leaving unexposed areas. Completed the invention.

That is, the present invention is a photo-crosslinkable polymer obtained by modifying a polyimide precursor derived from an aromatic tetracarboxylic acid or its mono- or di-anhydride and an aromatic diamine with a compound having a photosensitive group. A combined composition was prepared and applied on a substrate to form a film, and this film was imagewise exposed to crosslink the exposed part, and the unexposed part was dissolved and removed with a developing solution and crosslinked. In the method of heating the exposed film to form a polyimide resin film, a mixed solvent of an aprotic polar solvent and a cycloparaffinic hydrocarbon or a cycloparaffinic hydrocarbon compound is used as a developer, and a rinse liquid is used. Also, it is characterized by using a cycloparaffinic hydrocarbon or a mixed solvent of a cycloparaffinic hydrocarbon compound and a non-polar solvent.

By using the above-mentioned developing / rinsing solution according to the present invention, the developing / rinsing solution containing an aromatic hydrocarbon compound which has been conventionally used has a developing ability equal to or higher than that of the conventional developing / rinsing solution. There is no unexposed portion remaining in terms of film rate, and there is no need to change process control when an aromatic hydrocarbon compound is used, that is, the equipment for pattern formation is not changed.

The photocrosslinkable polymer composition used in the present invention has the following general formula (I):

[Chemical 1]

(Where Ar is

[Chemical 2]

Ar 'is

[Chemical 3] n represents a repeating unit of one or more polyamic acid) or a polyimide precursor derived from an aromatic diamine and an aromatic tetracarboxylic acid or an acid monoanhydride or an acid dianhydride, that is, a polyamic acid. It is obtained by modification with a compound having a photosensitive group.

Specific examples of the aromatic tetracarboxylic dianhydride used in the production of the above polyamic acid include pyromellitic dianhydride (PMDA), 3,4,3 ', 4'.
-Benzophenone tetracarboxylic acid dianhydride (BTD
A) 1,4,5,5-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride 3,3 ', 4,4'-diphenyltetracarboxylic dianhydride, 2,2', 3,3'-diphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-diphenyltetracarboxylic Acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis [4- (3,
4-dicarboxyphenoxy) phenyl] propane dianhydride, 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride Thing, screw (3,4
-Dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride and perylene-3,4,9,10-tetracarboxylic dianhydride, diphenylthioether tetracarboxylic dianhydride , And diphenylsulfone tetracarboxylic dianhydride, and mixtures thereof.

Specific examples of the other aromatic diamine used in the production of the above polyamic acid include m- or p-phenylenediamine, 4,4'- or 3,3'-diaminobiphenyl, 4,4'- or 3,3'-diaminodiphenyl ether, 4,4'- or 3,3'-diaminodiphenylmethane, 4,4'- or 3,3'-diaminodiphenyl sulfone, 4,4'- or 3 3,3'-thiodianiline, bis- (4-aminophenyl) bis (trifluoromethyl) methane, 4,4 '
-Diaminobenzophenone, 1,5-diaminonaphthalene, bis- (4-aminophenyl) -dimethylsilane,
Bis- (4-aminophenyl) -diethylsilane, bis- (4-aminophenyl) -diphenylsilane, bis-
(4-Aminophenyloxy) -dimethylsilane, bis-
(4-Aminophenyl) -ethylphosphine oxide, N- [bis- (4-aminophenyl)]-N-methylamine, N- [bis- (4-aminophenyl)]-N
-Phenylamine, 4,4'-methylenebis- (o-chloroaniline), 4,4'-methylenebis- (3-methylaniline), 4,4'-methylenebis- (2-ethylanilene), 4,4'- Methylenebis- (2-methoxyaniline), 5,5'-methylenebis- (2-aminophenol), 4,4'-methylenebis- (2-methylaniline), 4,4'-oxybis- (2-methoxyaniline) 4,4'-oxybis- (2-chloroaniline), 5,5-oxybis- (2-aminophenol), 4,4'-thiobis- (2-methylaniline),
4,4'-thiobis- (2-methoxyaniline), 4,
4'-thiobis- (2-chloroaniline), 4,4'-
Sulfonylbis- (2-methylaniline), 4,4'-
Sulfonylbis- (2-ethoxyaniline), 4,4 '
-Sulfonylbis- (2-chloroaniline), 5,5 '
-Sulfonylbis- (2-aminophenol), 3,
3'-dimethyl-4,4'-diaminobenzophenone,
3,3'-dimethoxy-4,4'-diaminobenzophenone, 3,3'-dichloro-4,4'-diaminobenzophenone, 4,4'-oxydianiline, 4,4'-isopropylidenedianiline, 3 , 3'-dichlorobenzidine,
3,3'-Dimethylpentidine, 3,3'-dimethoxybenzidine, 3,3'-dicarboxybenzidine, diaminotoluene, 4,4'-methylenebis- (3-carboxyaniline) and various esters thereof Kind, 5-
Amino-1- (4-aminophenyl) -1,3,3-trimethylindane and 6-amino-1- (4'-aminophenol) -1,3,3-trimethylindane, and mixtures thereof. .

The modification of the polyimide precursor with a compound having a photosensitive group is carried out by mixing a compound having a photosensitive group into the polyimide precursor or by introducing a photosensitive group into a side chain of the polyimide precursor. Be seen.

The compound having a photosensitive group to be mixed with the polyimide precursor is a compound known as a photosensitive monomer, for example, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate. , (Meth) acrylates such as N, N-dimethylaminoethylmethacrylate, mercapto compounds such as thioglycolic acid, maleimides such as phenylsulfonylmaleimide, and isocyanates such as ethylmethacrylate methacrylate. These photosensitive monomers were added to the polyimide precursor in an amount of 0.01
% To 100% by weight are mixed.

The photosensitive group introduced into the side chain of the polyimide precursor is typically a group having a carbon-carbon double bond, such as vinyl group, allyl group, acryl group, methacryl group, cinnamyl group, maleimide. Examples thereof include groups having a group, but are not limited thereto. Then, these photosensitive groups are introduced into the side chain of the polyimide precursor through a chemical bond such as an ester bond, an ether bond, an amide bond, a urethane bond, and a urea bond, or directly into an aromatic nucleus. To impart photosensitivity to the polyimide precursor.

The compound used for introducing a photosensitive group into the side chain of this polyimide precursor is, for example, cinnamic acid,
Cinnamic acid chloride, α-cyanocinnamic acid chloride,
Examples thereof include cinnamylidene acetic acid chloride, α-cyanocinnamylidene acetic acid chloride, furyl acrylic acid chloride, glycidyl cinnamate, and ethyl methacrylate methacrylate.

The photocrosslinkable polymer composition obtained by modifying the polyimide precursor with a compound having a photosensitive group as described above may contain a sensitizer for the purpose of improving its photosensitivity. it can. Examples of the sensitizer include benzophenones, benzophenones such as 4,4′-bis (dimethylamino) benzophenone, benzoin ethers, anthraquinones or thioxanthone derivatives, and 2,
Bisazido acids such as 6-bis- (4'-diethylaminobenzal) -cyclohexanone, mercapto compounds such as 1-phenyl-5-mercaptotetrazole, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) -Oximes such as oximes, imidazoles such as 2,4,5-triphenylimidazolyl dimer, and the like.

The photocrosslinkable polymer composition thus prepared is preferably dissolved in a solvent and diluted for application to a substrate to reduce its viscosity. The solvent used in this case is N, N'-dimethylformamide, N, N '
-Dimethylacetamide, γ-butyrolactone, N-methylpyrrolidone and the like, but are not limited thereto.

The photocrosslinkable polymer composition diluted with a solvent is then applied onto the substrate. As a method of applying this substrate, a spin coater, a roll coater, etc. are typical, and as a substrate, a silicon wafer, gallium, arsenic wafer, glass, ceramics, a copper plate, or a substrate having elements formed on these substrates is typical. Take as an example.

The coating film of the photocrosslinkable polymer composition thus applied on the substrate is then subjected to a drying step. In this drying step, baking with a circulating oven, a hot plate, or an infrared heater is generally used, but the baking is not limited to these. The baking temperature is preferably 50 to 120 ° C. The drying time varies depending on the film thickness, but is 3 minutes to 15 hours. The film thickness after drying is preferably 0.1 to 200 μm, but is not limited to this film thickness.

The coating of the photocrosslinkable polymer composition thus applied to the substrate and dried is then subjected to imagewise exposure. As an exposure method, a method of irradiating ultraviolet rays through a photomask by an ultraviolet exposure device used in a usual photoresist process is used. Although the exposure time varies depending on the photocrosslinkable polymer, the kind and amount of the additive, the light intensity of the exposure machine, etc., the optimum time is generally set to 1 second to 1 hour.

In some cases, a heat treatment is further performed after the exposure,
The heat treatment temperature at that time is 40 to 150 ° C., and the time is 1 second to
1 hour is good. As a heating method at that time, a circulation oven, a hot plate, an infrared heater, or the like is used as in the baking method.

Then, the coating film after the imagewise exposure is subjected to a developing step. The development is carried out by removing the portion which is cured by the imagewise exposure and becomes insoluble in the solvent on the substrate, and the unexposed portion which is soluble in the solvent is dissolved and removed by the solvent. In the present invention, a solvent used for this development, that is, a developing solution is a mixed solvent in which a good solvent and a poor solvent of the polymer are combined, and is N, N'-dimethylformamide or N, N'-dimethyl. Good solvent such as acetamide, γ-butyrolactone, N-methylpyrrolidone, etc., cycloparaffinic hydrocarbon such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane or cycloparaffinic hydrocarbon such as cyclohexanol, cyclohexanone It is characterized in that a mixed solvent with a poor solvent, which is one kind or a mixture of two or more kinds selected from hydrogen compounds, is used. By using a mixture of a poor solvent and a good solvent selected from cycloaliphatic hydrocarbons and their compounds as a developing solution, aromatic hydrocarbons that have been used conventionally and can no longer be used due to regulations for environmental protection in the future The same development rate, resolution, and high residual film ratio of the polyimide resin film formed after development can be obtained with the same solvent, and the process line for forming the polyimide pattern, which used aromatic hydrocarbons, remains unchanged. Can be used in.

As the good solvent, N, N'-dimethylformamide, N, N'-dimethylacetamide, cyclopentanone, cyclohexanone, N-methylpyrrolidone, γ
-Butyrolactone, hexamethylphosphoric triamide, acetonitrile, tetrahydrofuran and the like,
It is not limited to these as long as it can dissolve the polymer. These may be used alone or as a mixture of two or more kinds.

Examples of the poor solvent include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane and other cycloparaffinic hydrocarbon compounds, or cyclohexanol, cyclohexanone and other cycloparaffinic hydrocarbon compounds, acetone, methyl ethyl ketone and methyl. Examples thereof include, but are not limited to, cellosolve, ethyl cellosolve, isopropyl cellosolve, n-propyl alcohol, isobutyl alcohol and the like. Further, these may be used alone or as a mixture of two or more kinds.

The developing solution dissolves and removes the photosensitive polyimide precursor in the unexposed area, and its solubility is an important parameter in selecting the solvent. In the present invention, the cohesive energy density δ represented by the following well-known SMALL formula, δ = ρΣF / M, where M: unit molecular weight of polymer ρ: density F: cohesive energy / molar capacity The solubility is judged. Table 1 shows the cohesive energy density δ of each solvent.

[0031]

[Table 1]

The cohesive energy density δ _MIX of the mixed solvent
Is δ _MIX = (X ₁ V ₁ δ ₁ + X ₂ V ₂ δ ₂ ...) / (X ₁ V ₁ + X ₂ V ₂
...) However, X _eta: molar fraction, V _eta: molar volume, [delta] _eta: determined by equation such as cohesive energy density [delta] of the components. From this, using γ-butyrolactone as a good solvent, the solubility of the mixture with xylene, which is an aromatic hydrocarbon, and the solubility of the mixed solvent with cyclohexanone, which is a cycloaliphatic hydrocarbon compound instead of xylene, are almost the same. It turns out that

The developing solution in the present invention is a mixed solvent of a good solvent and a poor solvent, and the cycloaliphatic hydrocarbon such as cyclohexanone is used in the range of 10 to 90% by weight based on the weight of all the solvents. The optimum amount may be selected depending on the mixing ratio with a good solvent.

When the cycloaliphatic hydrocarbon is mixed in excess of these ranges, the polyimide precursor in the exposed area is also soluble and the residual film rate is lowered, and pattern formation becomes impossible.
This causes problems in the process such as cracks in the exposed area. Examples of the developing method include spray development, dip development, ultrasonic development and puddle development. The developed patterned polyimide precursor coating is immediately rinsed with a rinse to remove the developer and dissolved polyimide precursor. The rinse liquid is usually used alone or as a mixture of two or more kinds.

The resulting patterned polyimide precursor coating film is thermoset at a final temperature of 200 to 550 ° C. for 5 minutes to 5 hours to be converted into a polyimide resin film. Typical examples of the heat curing method include heating with a circulation oven, a hot plate, and an infrared heater, but the heat curing method is not limited to these and other means may be adopted as long as heat curing can be achieved.

For example, ether such as methyl acetate, ethyl acetate, butyl acetate and pental acetate, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, methanol, ethanol, n-propyne alcohol, isopropyl sulcol, water, 1-methoxy- Examples include, but are not limited to, 2-propanol and cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, and the like. Further, cycloparaffin hydrocarbons and cycloparaffin hydrocarbon compounds such as cyclohexanol and cyclohexane are also used.

[0037]

By patterning a photocrosslinkable polymer composition using the method of the present invention, it has been widely used in the past due to its cost efficiency. It can be used in the polyimide pattern formation method as a developer of a mixture with a good solvent instead of a poor solvent of an aromatic hydrocarbon, and at that time, the resolution, the developing rate and the residual rate of the polyimide film which are almost the same as those of an aromatic hydrocarbon. Thus, the unexposed area of the photosensitive polyimide precursor can be developed and can be applied as it is without changing the above steps when an aromatic hydrocarbon is used.

Next, the present invention and its effects will be explained with reference to examples, but the present invention is not construed as being limited to these examples.

Preparation Example of Polyimide Precursor 3 ', 3,4', 4-benzophenone tetracarboxylic anhydride, meta-phenylenediamine and oxydianiline were mixed and reacted to obtain their hydroxyethyl methacrylate esters.

This material was mixed with N-methyl-2-pyrrolidone, tetraethylene glycol diacrylate and triethoxysilylpropyl urea plus the same amount of methyl alcohol for 1 hour. Then 1,4,4-trimethyl-2,3-diazabicyclo (3,2,2) non-
2-ene 2,3-dioxide and bis (2-ortho-chlorophenyl-4,5-diphenyl) imidazole and 2-mercaptobenzoxazole and 2,3,6,7
-Tetrahydro-1,1,7,7-tetramethyl-11-
Oxo-1H, 5H, 11H- (1) benzopyrano-
[5,7,8, ij] quinolidine-10-carboxylic acid ethyl ester was mixed with this and stirred for 8 hours. The product was filtered to obtain Resin Varnish 1 as a uniform solution.

Example 1 A resin varnish 1 was applied onto a silicon wafer using a spin coater and baked at 70 ° C. and 90 ° C. for 3 minutes on a hot plate to obtain a film thickness of 10 μm. 3 μm on this film
PLA-501F made by Canon Co., Ltd. with a photomask on which a line and space of ~ 20 μm is printed in close contact
Exposure was performed using an exposure machine for an integrated time of 30 seconds. A wafer that was not exposed at the same time was prepared and used to calculate the development time. That is, the development time for completely removing the polyimide precursor coated on this wafer was calculated, and the development was carried out for 1.5 times the development time.

Next, spray development was performed with a developing solution of γ-butyrolactone / cyclohexanone = 30/70 (weight ratio), and then butyl acetate / cyclohexanone = 8.
Spray rinsing was performed for 16 seconds using 5/15 as the rinse liquid. The development time was 18 seconds. The resolution (narrowest line width) of the obtained pattern was 10 μm. The obtained pattern was sharp and no undercut or swelling was observed. The change in the film thickness of the polyimide pattern thus obtained is determined by the fact that the thickness of the coating film formed on the silicon wafer by the solution of the polyimide precursor is 10
It was about 97% with respect to μm.

Comparative Example A coating film was formed in the same manner as in Example, exposed for 30 seconds, and then γ-
After performing spray development with butyrolactone / xylene = 50/50 (weight ratio), rinse with xylene to form a polyimide precursor pattern. The resolution is about 10 μm, and the residual film rate of the formed polyimide resin film is about 94%.
Met. The time required for development was 12 seconds, which was almost the same as that in the example.

Claims (1)

[Claims] 1. A photocrosslinkable polymer composition obtained by modifying a polyimide precursor derived from an aromatic tetracarboxylic acid or its mono- or di-anhydride and an aromatic diamine with a compound having a photosensitive group. To form a film on the substrate, imagewise expose this film, dissolve and remove the unexposed part with a developing solution, and heat the remaining exposed part of the film to convert it to a polyimide resin. In the method for forming a patterned polyimide resin film on a substrate by using a mixed solvent of an aprotic polar solvent and a cycloparaffin hydrocarbon or a cycloparaffin hydrocarbon compound as a developer, The above method.