JPH06256995A - Electrodeposition coating method for photoresist and production of resist pattern - Google Patents

Abstract

(57) [Summary] [Objective] To provide an electrodeposition coating method for a photoresist and a method for producing a resist pattern without causing unevenness in film thickness and deterioration of the appearance of a coating film. [Structure] A substrate having a copper layer on its surface is subjected to surface treatment using a chemical polishing liquid, washed with water, and then an electrodeposition liquid containing a photoresist component or a filtrate obtained by ultrafiltration of the electrodeposition liquid is physically applied to the substrate. And the electrodeposition solution is replaced with a filtrate obtained by ultrafiltration of the electrodeposition solution, and then electrodeposition coating is carried out, and the electrodeposition coating method of the photoresist and the electrodeposition coating method. A method for producing a resist pattern, which comprises exposing a photoresist to form an image and then developing it after forming a photoresist on the substrate by a coating method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrodeposition coating a photoresist and a method for producing a resist pattern.

[0002]

2. Description of the Related Art Conventionally, when a printed circuit board is manufactured, a photoresist layer is formed on the surface of a copper-clad laminate, and then actinic rays are imagewise irradiated to form a resist pattern. In this step, various methods are adopted for forming the photoresist layer. For example, a method of coating a photocurable resin composition solution (coating liquid) by a coating method such as dip coating, roll coating, curtain coating, or a method of laminating a film (photosensitive film) of a photosensitive resin composition is known. Has been. Among these methods, the method of laminating the photosensitive film is
Since a photoresist layer having a uniform thickness can be easily formed, it is currently used as the mainstream method.

Recently, as the density and precision of printed circuit boards have increased, higher quality resist patterns have been required. That is, it is desired that the resist pattern has no pinhole and is well adhered to the surface of the underlying substrate. However, it is known that the method of laminating the photosensitive film, which is the mainstream at present, has a limit to meet such demand. In this method, the ability to follow unevenness on the substrate surface caused by dents during manufacturing of the substrate, unevenness of polishing, meshes of the glass cloth of the inner layer of the substrate, unevenness of copper plating pits on the surface, etc. is poor. However, it is difficult to obtain sufficient adhesion. This difficulty is caused by laminating films under reduced pressure (Japanese Patent Publication No. 59-
3740), but this requires special and expensive equipment.

For these reasons, solution coating methods such as dip coating, roll coating and curtain coating have come to be reviewed again in recent years. However, these coating methods have problems such as difficulty in controlling the coating film, insufficient uniformity of the film thickness, and generation of pinholes.

Therefore, recently, a method of forming a photoresist layer by an electrodeposition coating method has been proposed as a new method. According to this method, the adhesiveness of the resist is improved, the conformability to irregularities on the substrate surface is good, a photoresist layer having a uniform film thickness can be formed in a short time, and the working solution is an aqueous solution It has the advantage that it can prevent the pollution of the above and there is no problem in disaster prevention. Therefore, some proposals have recently been made regarding a method for forming a photoresist layer by an electrodeposition coating method and a composition of an electrodeposition bath suitable for the method.

However, according to the study by the present inventors, the method of forming a photoresist layer by the electrodeposition coating method has many advantages described above, while its operation process is different from other methods. It has become clear that careful consideration is required. In particular, pretreatment of the substrate as a preliminary step of electrodeposition coating is extremely important.If the substrate whose surface is corroded or oily is directly electrodeposited, the photo The film thickness of the resist becomes extremely non-uniform, and the formation of a resist pattern by subsequent exposure and development is also hindered. Therefore, the substrate surface must be uniformly cleaned by pretreatment before electrodeposition coating.

As a method for pretreating the surface of the substrate, there are usually degreasing, pickling, physical polishing, chemical polishing, etc. Pickling alone is not enough, and in the case of a substrate with through holes, physical polishing alone is not enough to process the inside of the through holes. Therefore, chemical polishing is often used for pretreatment of the substrate surface when the photoresist layer is formed by electrodeposition coating.

However, in the case of chemical polishing, washing and draining are performed to wash away the chemical polishing liquid adhering to the substrate surface as disclosed in Japanese Patent Laid-Open No. 1-7690. When the substrate is dipped in and the electrodeposition coating is performed, there is a problem that the film thickness of the photoresist after the electrodeposition coating is largely varied and the appearance of the coating film is significantly deteriorated. Further, when a substrate having a through hole is used, there is a problem that the film thickness in the through hole is thin or the inside of the through hole is not electrodeposited. In addition, JP-A-2-236
Japanese Patent Laid-Open No. 93 describes that after the water washing step after pickling, the electrodeposition coating of the resist is performed after being soaked in the electrodeposition solution in the pre-dip tank, but after the water washing step after chemical polishing, Even if the substrate is simply immersed in the pre-dip bath for a while and the substrate is soaked in the electrodeposition solution, there is a large variation in the film thickness of the photoresist and the coating film appearance is significantly reduced. There was a problem that it was thin or the inside of the through hole was not electrodeposited.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method for electrodeposition coating of photoresist and a method for producing a resist pattern, which does not cause unevenness of film thickness or deterioration of appearance of the coating film.

[0010]

The inventors of the present invention have earnestly studied the causes of the above-mentioned unevenness of the film thickness and the deterioration of the appearance of the coating film. As a result, the substrate after the chemical polishing is subjected to a pretreatment such as ordinary degreasing or pickling. It was found that the water once attached to the substrate surface is not easily replaced with the electrodeposition liquid because the adhesive force with water becomes stronger than that of the subsequent substrate. For this reason, after chemical polishing, even if the substrate with water adhered to the surface by water washing is dipped in the electrodeposition liquid and left for a while to get familiar, the water on the substrate surface is completely replaced with the electrodeposition liquid. However, it was judged that unevenness of the film thickness and deterioration of the appearance of the coating film would occur due to the electrodeposition coating in that state.

The present invention was made on the basis of the above-mentioned findings. It was chemically polished, washed with water, and a substrate wet with water was electro-deposited, or the electro-deposition liquid showing the same effect was ultrafiltered. As a result of the finding that water physically attached to the surface of the substrate can be removed by physically striking with the filtrate, and the electrodeposition solution or the filtrate obtained by ultrafiltration of the electrodeposition solution can uniformly wet the substrate surface. Is. Of course, when it gets wet with electrodeposition liquid,
The electrodeposition coating is possible immediately, and even when the electrodeposition solution is wet with the ultrafiltration filtrate, the substrate surface can be easily replaced with the electrodeposition solution by immersing the substrate in the electrodeposition solution next time. To be done.
It was confirmed that the thickness of the obtained electrodeposited film was uniform and the appearance of the coating film was good, and the present invention was completed.

That is, according to the present invention, a substrate having a copper layer on its surface is subjected to a surface treatment using a chemical polishing liquid, washed with water, and then an electrodeposition liquid containing a photoresist component or a filtrate obtained by ultrafiltration of the electrodeposition liquid. Is physically applied to the substrate and the water film on the surface of the substrate is replaced with an electrodeposition liquid or a filtrate obtained by ultrafiltration of the electrodeposition liquid,
The present invention relates to a method for electrodeposition coating a photoresist, which is characterized by performing electrodeposition coating.

The present invention also relates to a method for producing a resist pattern, which comprises exposing a photoresist imagewise and developing it after forming a photoresist layer on the substrate by the above electrodeposition coating method.

The present invention will be described in detail below. First,
The electrodeposition coating method of the photoresist of the present invention will be described in detail. In the present invention, chemical polishing using a chemical polishing liquid is performed as the surface treatment, but prior to chemical polishing, alkali degreasing using sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium phosphate, etc., trichlorethylene, perk Degreasing using solvent degreasing, such as L-ethylene,
It is also possible to perform pickling with sulfuric acid or the like, physical polishing represented by buff polishing, and the like.

The chemical polishing liquid used in the present invention is not particularly limited and various ones can be used, but an aqueous solution containing sulfuric acid and hydrogen peroxide, a persulfate such as sodium persulfate, potassium persulfate or ammonium persulfate is used. An aqueous solution containing a sulfate is suitable.

In the case of an aqueous solution containing sulfuric acid and hydrogen peroxide, the concentration of sulfuric acid is preferably 0.5 to 30% by weight, particularly 5 to 2%.
0% by weight is more preferred. When the concentration of sulfuric acid is less than 0.5% by weight, the chemical polishing effect is not sufficiently exerted, and
If it exceeds 30% by weight, it is uneconomical and not preferable. On the other hand, the concentration of hydrogen peroxide is preferably 0.5 to 50% by weight, more preferably 1 to 20% by weight.
If the concentration of hydrogen peroxide is less than 0.5% by weight, the chemical polishing effect is not sufficiently exerted, and if it exceeds 50% by weight, it is uneconomical and dangerous, which is not preferable.

In the case of an aqueous solution containing persulfate,
The concentration of persulfate is preferably 1 to 50% by weight, more preferably 5 to 35% by weight. If the concentration of persulfate is less than 1% by weight, the chemical polishing effect is not sufficiently exerted, and if it exceeds 50% by weight, it is uneconomical and not preferable. It should be noted that potassium persulfate dissolves only in about 10% by weight in water and its concentration is limited. In addition to the above main components, amines, alcohols, glycol ethers, surfactants, etc. can be appropriately added to the chemical polishing liquid, if necessary.

These chemical polishing liquids are usually used in an amount of 10-50.
It is preferably used in a temperature range of ℃ (it takes 5 seconds to 10 minutes to polish 1 μm of copper on the surface of the substrate), especially 2
It is preferably used in a temperature range of 0 to 40 ° C. (it takes 10 seconds to 3 minutes to polish copper on the surface of a substrate to 1 μm). If the temperature is lower than 10 ° C., the solubility of the produced CuSO ₄ becomes too low, and the CuSO ₄ tends to be deposited on the copper surface.
On the other hand, if the temperature exceeds 50 ° C., the chemical polishing rate is too fast, and the decomposition of hydrogen peroxide H ₂ O ₂ is promoted, which makes it difficult to control the polishing amount.

The chemical polishing is carried out by a method of immersing the substrate in the chemical polishing liquid, a method of spraying the chemical polishing liquid on the surface of the substrate, or the like. The polishing amount (indicated by the amount of reduction in thickness) of the copper on the substrate surface by the pretreatment is important and is preferably 0.5 μm or more, more preferably 1.0 μm or more, and 1.5 μm.
The above is particularly preferable. If the polishing amount is less than 0.5 μm, the effect of pretreatment is small, and abnormal electrodeposition may be caused due to the contamination state of the copper surface. The amount of polishing can be measured by measuring the weight of the substrate before polishing and the weight of the substrate after polishing.

When the pretreatment is performed only by chemical polishing, the amount of copper to be polished needs to be 0.5 μm or more by chemical polishing alone, and other pretreatment methods such as physical polishing described later are also used. In this case, the total amount of polishing by each method including chemical polishing should be 0.5 μm or more.

The method of rinsing the chemical polishing liquid adhered to the substrate after chemical polishing is not particularly limited, and for example, a method of immersing the substrate in water, a method of spraying water on the surface of the substrate,
Examples include a method of exposing the substrate surface to running water.

The substrate thus chemically polished is
Next, electrodeposition coating is performed, but here, it is necessary to physically apply the electrodeposition liquid or the filtrate obtained by ultrafiltration of the electrodeposition liquid to the substrate. The method of applying the electrodeposition liquid or the filtrate obtained by ultrafiltration of the electrodeposition liquid to the substrate is not particularly limited, and the point is that water that physically adheres to the substrate surface by tapping the substrate surface with the liquid. Any method may be used as long as it is rapidly replaced with an electrodeposition solution or a filtrate obtained by ultrafiltration of the electrodeposition solution.

Among these methods, preferred examples are shown below. The electrodeposition liquid or the filtrate obtained by ultrafiltration of the electrodeposition liquid is sprayed or showered onto a substrate wet with water after chemical polishing. A method of spraying, a method of rubbing the surface of the substrate which has been wet with water after chemical polishing with a roll or brush to which an electrodeposition solution or a filtrate obtained by ultrafiltration of the electrodeposition solution has been previously attached, an electrodeposition solution Or in the filtrate obtained by ultrafiltration of the electrodeposition liquid,
A method of immersing a wet substrate in water after chemical polishing, and blowing out the liquid from a nozzle or the like toward the substrate in the liquid, an electrodeposition liquid or a filtrate obtained by ultrafiltration of the electrodeposition liquid,
There is a method of immersing a wet substrate in water after chemical polishing and rubbing the surface of the substrate with a roll, a brush or the like in the liquid. These may be performed alone or in combination of two or more.

By thus physically wetting the surface of the substrate wet with washing water after chemical polishing, which is a feature of the present invention, by the physical method, the electrodeposition solution or the filtrate obtained by ultrafiltration of the electrodeposition solution is used. , The next electrodeposition coating can be performed extremely smoothly.

The electrodeposition liquid as used herein refers to a photosensitive electrodeposition coating composition containing a photosensitive resin composition (photoresist component) used for electrodeposition coating, which will be described later. The filtrate obtained by ultrafiltration of the electrodeposition liquid is, for example, cellulose-based such as nitrocellulose or acetylcellulose, synthetic polymer-based such as polyacrylonitrile, polysulfone, polyvinyl alcohol or polyethylene, inorganic-based such as graphite or ceramics. Ultrafiltration membranes classified into
A filtrate obtained by assembling into a module of tubular type, spiral winding type, hollow type or the like and allowing the electrodeposition solution to pass through the module, and filtering the electrodeposition solution by a general ultrafiltration method. The thus obtained filtrate is referred to.

When a substrate having a through hole is used, the substrate that has undergone the above steps is once mechanically shaken or vibrated in the electrodeposition solution, or the electrodeposition solution is agitated or agitated. By applying ultrasonic vibration to the electrodeposition liquid,
Defoaming the inside of the through hole, filling the inside of the through hole with an electrodeposition liquid, and then performing electrodeposition coating is preferable from the viewpoint of uniform electrodeposition in the through hole.

Next, a photosensitive electrodeposition coating composition (hereinafter abbreviated as electrodeposition liquid) containing a photosensitive resin composition used for electrodeposition coating will be described. The electrodeposition liquid includes anion type and cation type as electrodeposition coating types. The former is a method in which the resin is dissociated into anions in the electrodeposition liquid, and the resin anions are electrophoresed on the substrate to be coated, which is the anode, to deposit on the substrate surface, and the latter is a method in which the resin is dissociated into cations. This is a method in which resin cations are electrophoresed on the substrate to be coated, which is the cathode, and are deposited on the substrate surface.

Therefore, in the case of an anion type, the main resin of the photosensitive resin composition contains a carboxyl group which is easily dissociated into anions, promotes the dissociation of ions, and makes the photosensitive resin composition water-soluble or water-soluble. As a neutralizing agent for dispersing, a base such as triethylamine, monoethanolamine, morpholine, ammonia, sodium hydroxide is added.

In the case of a cation type, the main resin of the photosensitive resin composition contains an amino group which is easily dissociated into cations to promote the dissociation of ions and to make the photosensitive resin composition water-soluble or water-soluble. An acid such as acetic acid, lactic acid, phosphoric acid, or sulfuric acid is added as a neutralizing agent for dispersing.

On the other hand, the photosensitive system is classified into a negative type and a positive type. The former is a method in which an exposed portion is photocured and becomes insoluble in a developing solution, and an unexposed portion is dissolved and developed.
The latter is a method of dissolving and developing the exposed portion by utilizing the property that the solubility in an alkaline aqueous solution or the like is increased by exposure such as an orthoquinonediazide compound. Therefore, in the case of the negative type, a compound having a photopolymerizable unsaturated bond and a photopolymerization initiator are required in the composition.

In the case of positive type, orthoquinonediazide compound, o-nitrobenzyl compound, and
A chemical amplification system comprising a compound having an acid-decomposable group such as t-butyl ester group and t-amyl ester group and a photoacid generator such as iodonium salt and sulfonium salt is used.

Representative examples of the photosensitive resin composition in each of the above cases are summarized as follows.

In the case of anionic / negative type: A carboxyl group-containing resin, an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in the molecule, and a photopolymerization initiator are main components. Here, the carboxyl group-containing resin is preferably a copolymer of acrylic acid, methacrylic acid, itaconic acid and the like with acrylic acid ester, methacrylic acid ester, styrene and the like.

The content of the carboxyl group is preferably such that the acid value is 30 to 250. When the acid value of the resin is less than 30, the water dispersibility is poor and the acid value is 25.
When it exceeds 0, the appearance of the electrodeposition film (photoresist) is poor. The weight average molecular weight of the resin is 1,000 to 150,0.
00 is preferable. When the molecular weight is less than 1,000, the mechanical strength of the electrodeposition film tends to be weak, and when it exceeds 150,000, the electrodeposition coatability tends to be poor.

The carboxyl group-containing resin may further contain a polymerizable unsaturated group. As such a resin, a glycidyl methacrylate is subjected to an addition reaction with a carboxyl group-containing resin, or a copolymer having a hydroxyl group-containing monomer as a copolymerization component, a monoisocyanate compound having a polymerizable unsaturated bond in the molecule, for example, , Β-methacryloylethyl isocyanate can be produced.

As another example of the carboxyl group-containing resin, α, β-ethylenically unsaturated dibasic acid or its anhydride is added to the unsaturated bond in the fatty acid chain in the esterified product of epoxy resin and unsaturated fatty acid. There is a resin. Further, an unsaturated fatty acid-modified high acid value alkyd resin can also be used in the present invention.

Further, α, β-unsaturated dicarboxylic acid anhydride was added to the conjugated diene polymer or conjugated diene copolymer, and further, α, β-unsaturated monocarboxylic acid ester having an alcoholic hydroxyl group was reacted. There is resin. It is preferable that the acid value and the molecular weight of these resins are both within the above ranges.

As the neutralizing agent used for these carboxyl group-containing resins, as mentioned above, there are, for example, bases such as triethylamine, monoethanolamine, morpholine, ammonia and sodium hydroxide, and these are used alone or as a mixture. Can be used.

The amount of the neutralizing agent used is preferably 0.3 to 1.0 equivalent based on 1 equivalent of the carboxyl group in the resin,
If the amount is less than 0.3 equivalent, the water dispersion stability of the electrodeposition liquid decreases,
If it exceeds 1.0 equivalent, the coating film thickness tends to be thin and the storage stability tends to be low, such being undesirable.

At least one polymerizable unsaturated bond is contained in the molecule.
Examples of the ethylenically unsaturated compound possessed by them include acrylic acid esters or methacrylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate and trimethylolpropane triacrylate. Acrylic acid ester or methacrylic acid ester of alkylene oxide adduct of bisphenol A is also useful.

As the photopolymerization initiator, benzophenone,
Known photopolymerization initiators such as ethylanthraquinone and ethylthioxanthone can be used.

These photosensitive resin compositions contain 20 to 50 parts by weight of an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in the molecule, based on 100 parts by weight of the carboxyl group-containing resin. Photopolymerization initiator 2-10
It is preferably contained in a ratio of parts by weight. If the amount of the ethylenically unsaturated compound exceeds 50 parts by weight, the water dispersibility of the composition will decrease, and if it is less than 20 parts by weight, the photocurability of the composition tends to decrease. If the photopolymerization initiator is also more than the above range, the water dispersibility decreases, and if it is too small,
Photocurability tends to decrease.

These photosensitive resin compositions may contain a colorant, a photo-coloring agent, a thermal polymerization inhibitor, a plasticizer, a filler and the like in addition to the above-mentioned three components.

In the case of cationic / negative type: The main components are a resin containing a primary to tertiary amino group, an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in the molecule, and a photopolymerization initiator. Here, as the primary to tertiary amino group-containing resin, for example, aminoethyl (meth) acrylate [(meth) acrylate means methacrylate and acrylate]. The same applies below],
N, N'-dimethylamino (meth) acrylate, N,
A copolymer of an amino group-containing polymerizable monomer such as N'-dimethylaminobutyl (meth) acrylate and an acrylic acid ester, a methacrylic acid ester or styrene is preferable. The amino group content is such that the amine value is 30 to 25.
The degree of 0 is preferable. When the amine value of the resin is less than 30, the water dispersibility is poor, and when the amine value is more than 250, the appearance of the electrodeposition film (photoresist) is poor. The weight average molecular weight of the resin is preferably 5,000 to 150,000. When the molecular weight is less than 5,000, the mechanical strength of the electrodeposition film tends to be weak, and when it exceeds 150,000, the electrodeposition coatability tends to be poor.

As another example of the amino group-containing resin, instead of the amino group-containing polymerizable monomer, for example, a glycidyl group-containing polymerizable monomer such as glycidyl (meth) acrylate, glycidyl (meth) acrylamide and acrylic acid are used. A copolymer with an ester, a methacrylic acid ester, styrene, etc. is synthesized, and the copolymer and dimethylamine,
Second such as diethanolamine, piperidine, morpholine
The resin obtained by adding a primary amine compound is mentioned. Further, amino resins such as melamine resin, urea resin, benzoguanamine resin and acetoguanamine resin can be used in the method of the present invention.

The amino group-containing resin may further contain a polymerizable unsaturated group. Such a resin is prepared, for example, by reacting a part of the glycidyl group contained in the base resin with an amino compound to open the ring, and then reacting the remaining glycidyl group with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid to form an unsaturated compound. It can be produced by introducing a saturated group or by introducing an unsaturated group by reacting an unsaturated monomer having a glycidyl group with a hydroxyl group such as hydroxyethyl acrylate or hydroxyethyl methacrylate.

As the neutralizing agent for these amino group-containing resins, as mentioned above, for example, acids such as acetic acid, propionic acid, lactic acid, formic acid, phosphoric acid and sulfuric acid can be used, and these can be used alone or as a mixture. it can. The amount of the neutralizing agent used is preferably 0.3 to 1.0 equivalent with respect to 1 equivalent of the amino group,
If it is less than 0.3 equivalent, the water dispersion stability of the electrodeposition liquid tends to decrease, and if it exceeds 1.0 equivalent, the coating film becomes thin,
Storage stability tends to decrease, which is not preferable.

At least one polymerizable unsaturated bond is contained in the molecule.
As for the ethylenically unsaturated compound and the photopolymerization initiator which each has, the same ones as exemplified in the case of the anionic / negative type can be used.

These photosensitive resin compositions contain 20 to 50 parts by weight of an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in one molecule with respect to 100 parts by weight of the above amino group-containing resin. It is preferable that the photopolymerization initiator is contained in a proportion of 2 to 10 parts by weight. Use outside the respective ranges is not preferable for the same reason as described for the anionic / negative type.

These photosensitive resin compositions may contain a colorant, a photo-coloring agent, a thermal polymerization inhibitor, a plasticizer, a filler and the like in addition to the above-mentioned three components.

Anionic / Positive type In general, a resin system having a quinonediazide group and a carboxyl group, or a mixture of a compound having two or more quinonediazide groups in a molecule (photosensitizer) and a carboxyl group-containing resin There is a system.

Examples of the former include carboxyl group-containing monomers such as methacrylic acid, acrylic acid and itaconic acid, and 2
-Hydroxyethyl acrylate, t-butylaminoethyl methacrylate, etc. were obtained by reacting 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride, 1,2-benzoquinone-2-diazide-4-sulfonyl chloride, etc. There is a resin obtained by copolymerizing a monomer and a monomer such as an acrylic acid ester and a methacrylic acid ester.
Here, the content of the quinonediazide group in the resin is preferably 0.04 to 0.20 per 100 of the molecular weight of the resin,
If it is less than 0.04, the amount of carboxylic acid generated at the time of exposure is small and development tends to be difficult. If it exceeds 0.20, the electrodeposition film (photoresist) tends to be hard and prone to cracking. is there.

As an example of the latter, the carboxyl group-containing resin described in the case of the anionic / negative type can be used in combination with gallic acid ester, trihydroxybenzophenone, etc.
A photosensitizer obtained by reacting 2-naphthoquinone-2-diazide-5-sulfonyl chloride, 1,2-benzoquinone-2-diazido-4-sulfonyl chloride, etc., with a total amount of the carboxyl group-containing resin and the photosensitizer of 100 wt. There are 5 to 50 parts by weight of the composition mixed with parts. When the content of the photosensitizer is less than 5 parts by weight, the photosensitivity is low, and when it exceeds 50 parts by weight, the water dispersion stability of the electrodeposition liquid is lowered.

The acid value and weight average molecular weight of the former and latter resins are the same as those of the carboxyl group-containing resin described in the case of the anionic / negative type. The same applies to typical examples and amounts of the neutralizing agent used. Further, these photosensitive resin compositions, in addition to the main components described above, a colorant,
It may contain a photo-coloring agent, a thermal polymerization inhibitor, a plasticizer, a filler and the like.

In the case of cationic type / positive type, a resin containing a primary to tertiary amino group, to which quinonediazide is added in the molecule, is generally used as a main component. A polymerizable monomer having a secondary amino group, for example, t-butylaminoethyl methacrylate, t-butylaminostyrene, etc., which is reacted with a quinonediazide described in the case of an anion type / positive type, a cationic type / negative type monomer. 1 mentioned in the case
~ It can be obtained by copolymerizing a tertiary amino group-containing monomer and, if necessary, a polymerizable monomer such as acrylic acid ester, methacrylic acid ester, and styrene.

The amino group content of the amino group-containing resin having quinonediazide added in the molecule has an amine value of 30 to 25.
The degree of 0 is preferable. If the amine value of the resin is less than 30, the water dispersibility is poor, and if the amine value exceeds 250,
The appearance of the electrodeposition film (photoresist) is inferior. The weight average molecular weight of the resin is preferably 5,000 to 150,000. When the molecular weight is less than 5,000, the mechanical strength of the electrodeposition film tends to be weak, and when it exceeds 150,000, the electrodeposition coatability tends to be poor.

The content of the quinonediazide group in the resin is preferably 0.04 to 0.20 per 100 molecular weight of the resin. If it is less than 0.04, the amount of carboxylic acid generated during exposure is small and development is difficult. If it exceeds 0.20, the glass transition point of the resin becomes high, and the electrodeposition film (photoresist) becomes hard and cracks easily occur.

The same applies to typical examples and amounts of the neutralizing agents used for these amino group-containing resins. Further, these photosensitive resin compositions may contain a colorant, a photocoloring agent, a thermal polymerization inhibitor, a plasticizer, a filler and the like in addition to the above-mentioned main components.

To prepare an electrodeposition liquid using these photosensitive resin compositions, generally, the photosensitive resin composition is first homogenized in a hydrophilic solvent such as methoxyethanol, ethoxyethanol, diethylene glycol or dioxane. It is desirable to dissolve in. In this case, the hydrophilic solvent used when synthesizing the resin may be used as it is, or the synthetic solvent may be distilled off and then another hydrophilic solvent may be added.
Two or more kinds of hydrophilic solvents may be used. The amount of the hydrophilic solvent used is preferably 300 parts by weight or less based on 100 parts by weight of the photosensitive resin composition.

Next, the neutralizing agent shown in each of the above cases is added to this solution to neutralize the resin, thereby facilitating water-solubilization or water-dispersion. Finally, water can be added to dissolve or disperse the photosensitive resin composition in water to prepare an electrodeposition liquid. The solid content of the electrodeposition liquid is preferably 5 to 20% by weight, and the pH of the electrodeposition liquid is preferably 6.0 to 9.0 in the case of an anionic system and 3.0 to 9.0 in the case of a cationic system.

Further, a surfactant may be appropriately added in order to enhance the water dispersibility and dispersion stability of the photosensitive resin composition. Further, a hydrophobic solvent such as toluene, xylene, and 2-ethylhexyl alcohol can be appropriately added to control the coating amount at the time of electrodeposition coating.

In the present invention, a substrate having a copper layer on its surface is used as the substrate on which the photoresist is formed by electrodeposition coating. This substrate may be a copper foil or a copper plate, or may be a copper-clad laminate in which a copper foil is laminated on the surface of a substrate such as glass epoxy resin or paper phenol resin. Further, it may be a substrate obtained by subjecting the surface of a copper foil to electrolytic and / or electroless copper plating. Of course, the surface of copper may be subjected to an antioxidant treatment with another metal, or may be an alloy containing other metal inside copper. Through holes may be formed in these substrates.

In order to perform electrodeposition coating on a substrate having a copper layer on such a surface, the substrate is used as an anode when the electrodeposition liquid is anionic, and the substrate is used as a cathode when the electrodeposition liquid is cationic. In the case of a constant current method, it is preferably 10
A direct current of 400 mA / dm ² is applied, and in the case of the constant voltage method, a direct current voltage of preferably 50 to 400 V is applied for 10 seconds to 5 minutes. The temperature of the electrodeposition liquid at this time is 15 to 30.
It is preferable to control the temperature at ° C.

After the electrodeposition coating, the article to be coated is pulled up from the electrodeposition liquid, washed with water, drained and then dried with hot air or the like. At this time, if the drying temperature is too high, the quality of the photoresist deteriorates, so it is usually desirable to dry at 120 ° C. or lower.

Next, the resulting photoresist is imagewise irradiated with actinic rays, and when the photoresist is a chemical amplification system, it is further subjected to a post-heating step at 60 to 150 ° C. for 1 to 30 minutes, and then, A resist pattern can be obtained by development.

As a light source for actinic rays, wavelengths of 300 to 4 are used.
A device that emits a light beam of 50 nm, for example, a mercury vapor arc lamp, a carbon arc lamp, a xenon arc lamp, or the like is preferably used.

In the development, when a photoresist is formed with an anionic electrodeposition solution, it is usually sprayed with an aqueous alkali solution of sodium hydroxide, sodium carbonate, sodium metasilicate, potassium hydroxide or the like, or immersed in an aqueous alkali solution. When a photoresist is formed with a cationic electrodeposition liquid, an acidic liquid such as acetic acid, lactic acid or an aqueous solution thereof or an organic solvent such as ethanol, chlorothene, trichlene is usually sprayed. Alternatively, it is performed by immersing in such liquid.

[0068]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Synthesis Example 1 300 g of dioxane was added to a flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas introducing tube,
The mixture was stirred and heated to 90 ° C. while blowing nitrogen gas.
When the temperature became constant at 90 ° C, methacrylic acid 6
A mixture of 7.6 g, methyl methacrylate 166.6 g, n-butyl acrylate 165.8 g and azobisisobutyronitrile 4.0 g was dropped into the flask over 2 hours, and then at 90 ° C. for 3. It was kept warm while stirring for 5 hours.

Then, a mixture of 2 g of azobisdimethylvaleronitrile and 100 g of dioxane was dropped into the flask over 30 minutes, and then the mixture was again stirred at 90 ° C. for 4 hours.
I kept it warm for an hour.

The resin thus obtained had a weight average molecular weight of 35,000, an acid value of 108, and a solid content of the resin solution of 50.1% by weight.

To 150 g of the resin solution obtained in this synthesis example, 25 g of pentaerythritol triacrylate (UK Ester A-TMM-3 manufactured by Shin-Nakamura Chemical Co., Ltd.), 6 g of benzophenone and N, N'-tetraethyl-4,4 '.
-0.2 g of diaminobenzophenone was added and dissolved, and then 4.5 g of dimethylaminoethanol was added and dissolved.

850 g of deionized water was added to this solution with stirring to prepare an electrodeposition solution [hereinafter referred to as electrodeposition solution (A)]. The pH of the electrodeposition liquid (A) was 7.3 and the solid content was about 10% by weight.

Synthesis Example 2 452 g of dioxane was added to a flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas introducing tube.
Nitrogen gas was blown in while stirring and the temperature was raised to 90 ° C.
When the temperature became constant at 90 ° C, methacrylic acid 4
3.2 g, methyl methacrylate 132 g, acrylic acid n
-Butyl 185 g, 2-hydroxyethyl acrylate 3
A mixture consisting of 9.8 g and azobisisobutyronitrile 4 g was dropped into the flask over 2.5 hours, and then the mixture was kept at 90 ° C. for 3 hours while stirring. After 3 hours, 1.2 g of azobisisobutyronitrile was added to dioxane 40
The solution dissolved in g was dropped into the flask over 10 minutes,
Then, the mixture was kept at 90 ° C. for 4 hours while stirring again.

The resin thus obtained had a weight average molecular weight of 56,000, an acid value of 72, and a solid content of the resin solution of 44.6% by weight.

On the other hand, the photosensitizer was synthesized as follows. 21.2 g (0.1 mol) of n-propyl gallate and 53.7 g (0.2 mol) of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride were added to dioxane 50.
The solution dissolved in 0 ml was heated to 40 ° C. with stirring, and 21 g of triethylamine was added dropwise thereto over 30 minutes.
After the dropping, the mixture was reacted at 40 ° C. for another 3 hours, and then the reaction product was poured into a 0.1N hydrochloric acid aqueous solution, and the obtained precipitate was purified and filtered to obtain n-propyl gallate as a photosensitizer and 1,
55 g of an ester compound with 2-naphthoquinone-2-diazide-5-sulfonic acid was obtained.

Resin solution 170 obtained in this synthesis example 2
g, 20 g of the above photosensitizer and 5.8 g of triethylamine
Was mixed, and 760 g of deionized water was added to the obtained solution with stirring to prepare an electrodeposition solution. The obtained electrodeposition liquid [hereinafter referred to as the electrodeposition liquid (B)] had a pH of 7.9 and a solid content of about 10% by weight.

Example 1 A chemical polishing liquid (25 ° C.) containing 25 g / l of hydrogen peroxide, 150 g / l of sulfuric acid and 5 g / l of monobutyl cellosolve was previously left under high humidity to generate rust on a part of the surface. In addition, a double-sided copper-clad laminate (M
CL-E-61, H18D, manufactured by Hitachi Chemical Co., Ltd.,
300 mm × 500 mm) was immersed for 2 minutes (copper polishing amount 2.0 μm). The substrate was pulled up from the chemical polishing liquid, washed with running water, and the electrodeposition liquid (A) was uniformly sprayed on the substrate wet with washing water at a spray pressure of 1.0 kg / cm ² for 1 minute.

This substrate was immersed in the electrodeposition solution (A) as an anode, and a stainless plate (SUS30) having the same area was used as the cathode.
4) Soak and apply a DC voltage of 150 V at a temperature of 25 ° C to 3
It was applied for a period of time to perform electrodeposition coating. The substrate was pulled up from the electrodeposition liquid, washed with water and dried at 100 ° C. for 10 minutes, and the film thickness and appearance of the formed electrodeposition film (photoresist) were observed. The results are shown in Table 1.

The obtained photoresist was imagewise exposed through a negative mask with an ultrahigh pressure mercury lamp of 3 kW at a light amount of 100 mJ / cm ² , and then developed with a 1 wt% sodium carbonate aqueous solution to obtain a high resolution of 50 μm. It was possible to form a good resist pattern that had.

Example 2 Chemical polishing liquid containing ammonium persulfate 120 g / l (2
The same substrate as in Example 1 was immersed in 5 ° C.) for 1 minute (copper polishing amount 0.8 μm). Pull the substrate out of the chemical polishing liquid,
After washing with running water, the electrodeposition liquid (A) is filtered with an ultrafiltration membrane (NTU20).
20 P18B, manufactured by Nitto Denko Co., Ltd. The surface of the substrate wet with washing water was uniformly rubbed 5 times with a sponge roll soaked with a filtrate filtered through it.

This substrate was immersed in the electrodeposition liquid (A) as an anode, and electrodeposition coating and drying were performed under the same method and conditions as in Example 1 to observe the film thickness and appearance of the formed photoresist. The results are shown in Table 1. When the obtained photoresist was exposed and developed under the same method and conditions as in Example 1, a good resist pattern having a high resolution of 50 μm could be formed.

Example 3 A substrate similar to that of Example 1 was immersed in a chemical polishing liquid (30 ° C.) containing hydrogen peroxide 20 g / l and sulfuric acid / 50 g / l for 1.5 minutes (copper polishing amount 1.5 μm). ). The substrate was pulled up from the chemical polishing liquid, washed with running water, and then the substrate wet with the washing water was immersed in the electrodeposition liquid (A) and provided in the electrodeposition liquid (A) 10 mm away from the substrate. The electrodeposition liquid (A) was blown from the nozzle toward the substrate at a pressure of 1.5 kgf / cm ² , and the electrodeposition liquid (A) was uniformly sprayed on the substrate for 0.5 minutes.

This substrate was immersed in an electrodeposition liquid (A) as an anode, and electrodeposition coating and drying were performed under the same method and conditions as in Example 1 to observe the film thickness and appearance of the formed photoresist. The results are shown in Table 1. When the obtained photoresist was exposed and developed under the same method and conditions as in Example 1, a good resist pattern having a high resolution of 50 μm could be formed.

Example 4 Using the same chemical polishing liquid and substrate as in Example 1, Example 1
The substrate chemically polished under the same conditions as above is pulled up from the chemical polishing liquid, washed with running water, and then the substrate wet with washing water is electrodeposited (A).
The surface of the substrate in the electrodeposition liquid (A) was uniformly rubbed 4 times with a nylon brush.

This substrate was immersed in an electrodeposition liquid (A) as an anode, and electrodeposition coating and drying were performed under the same method and conditions as in Example 1 to observe the film thickness and appearance of the formed photoresist. The results are shown in Table 1. When the obtained photoresist was exposed and developed under the same method and conditions as in Example 1, a good resist pattern having a high resolution of 50 μm could be formed.

Example 5 A clean double-sided copper-clad laminate which was used in Example 1 and which was not rusted or contaminated on a part of the preliminary surface had a diameter of 0.4 mm to 1 mm. A drilled hole of 0.0 mm was formed, followed by copper plating, and a board having a copper plating layer formed on the surface of the double-sided copper-clad laminate and the hole wall of the through hole was prepared in the same manner as in Example 1. After leaving it under high humidity to generate rust on the surface and a part of the inside of the through hole and further contaminate it with fingerprints etc., dip this substrate in the chemical polishing liquid used in Example 1 for 1.5 minutes. Yes (copper polishing amount 1.5μ
m). After pulling up the substrate from the chemical polishing liquid and washing it with running water,
The electrodeposition solution (B) was uniformly sprayed onto the substrate wet with washing water at a spray pressure of 0.6 kg / cm ² for 2 minutes.

This substrate was immersed in the electrodeposition liquid (B), and the substrate was rocked 20 times with a stroke of 50 mm in the vertical direction, and then the substrate was used as an anode as it was, and a stainless steel plate of the same area was used as the cathode ( SUS304) was dipped and a DC voltage of 150 V was applied for 3 minutes to perform electrodeposition coating. The substrate was pulled up from the electrodeposition liquid, washed with water, and dried at 80 ° C. for 10 minutes, and the film thickness and appearance of the formed photoresist were observed. The results are shown in Table 1.

The obtained photoresist was imagewise exposed to a light amount of 300 mJ / cm ² by a 3 kW ultra-high pressure mercury lamp through a positive mask, and then developed with a 1 wt% sodium metasilicate aqueous solution. A good resist pattern having a resolution could be formed.

Example 6 The substrate having through holes used in Example 5 was immersed in the chemical polishing liquid used in Example 3 for 1 minute (copper polishing amount 1.0 μm). The substrate was pulled up from the chemical polishing liquid, washed with running water, and then the substrate wet with the washing water was filtered with an electrodeposition liquid (B) through an ultrafiltration membrane (NTU2120 F2E, manufactured by Nitto Denko Corporation) into a filtrate. Soak it in a nylon brush,
The surface of the substrate in this filtrate was rubbed uniformly 5 times.

This substrate was dipped in the electrodeposition liquid (B), and thereafter, defoaming in the through holes, electrodeposition coating and drying were carried out under the same method and conditions as in Example 5. The film thickness and appearance of the photoresist were observed, and the results are shown in Table 1. The obtained photoresist was exposed and developed in the same manner as in Example 5 and under the same conditions.
A good resist pattern having a high resolution of m could be formed.

Comparative Example 1 The same substrate as in Example 1 was directly immersed in the electrodeposition liquid (A) as an anode without chemical polishing treatment, and electrodeposition was carried out by the same method and conditions as in Example 1. After coating and drying, the film thickness and appearance of the formed photoresist were observed, and the results are shown in Table 1. The obtained photoresist was exposed and developed under the same method and conditions as in Example 1.

Comparative Example 2 A substrate similar to that of Example 1 was prepared by adding a 10 wt% sulfuric acid aqueous solution (2
It was dipped in 5 ° C.) for 2 minutes and pickled. The substrate was pulled up from the aqueous sulfuric acid solution, washed with running water, and the substrate wet with washing water was directly immersed in the electrodeposition liquid (A) as an anode, and electrodeposition coating and drying were performed in the same manner and conditions as in Example 1. After that, the film thickness and appearance of the formed photoresist were observed, and the results are shown in Table 1. The obtained photoresist was exposed and developed under the same method and conditions as in Example 1.

Comparative Example 3 The same substrate as in Example 1 was chemically polished under the same method and conditions as in Example 1, washed with water, and then the substrate wet with washing water was directly used as an anode in the electrodeposition solution (A). Immersion, electrodeposition coating and drying were performed under the same method and conditions as in Example 1, and the film thickness and appearance of the formed photoresist were observed. The results are shown in Table 1. The obtained photoresist was exposed and developed under the same method and conditions as in Example 1.

Comparative Example 4 A substrate having through holes similar to those in Example 5 was used in Example 5.
Chemically polished by the same method and conditions as described in (1) above, washed with water, and then directly immersed in the water for washing as a positive electrode in the electrodeposition solution (B), followed by electrodeposition coating and the same method and conditions as in Example 5. After drying, the film thickness and appearance of the formed photoresist were observed, and the results are shown in Table 1. The obtained photoresist was exposed and developed under the same method and conditions as in Example 5.

[0096]

[Table 1]

In Table 1, the "variation" of the film thickness is 1
The film thickness was measured evenly at 15 positions on each of the substrates using an eddy current film thickness meter (Permascope E111, manufactured by Fischer), and the maximum film thickness (μm) and the minimum film thickness (μm) of them were measured. The difference is expressed as variation.

In the case of Comparative Example 1 in which the substrate not subjected to the chemical polishing treatment was used, the portion of the substrate surface which was rusted due to dirt or corrosion was reflected in the photoresist after electrodeposition coating as uneven coating film, and the film thickness was The variation of is also large. Further, in the unexposed area of the substrate after development, a large amount of development residue that is not removed even by development occurs. Etching was difficult.

Further, in the case of Comparative Example 2 in which pickling was performed instead of chemical polishing, the appearance of the coating film was slightly improved as compared with Comparative Example 1, but the rust on the substrate surface was not sufficiently removed, As a result, uneven coating film was generated. Further, in the unexposed portion of the substrate after development, undeveloped portion was generated at a portion where the removal of rust was insufficient, and it was difficult to etch copper in that portion. However, as compared with Comparative Example 3, a step of physically replacing the water by physically hitting the substrate surface wet with the washing water according to the present invention with an electrodeposition liquid or a filtrate obtained by ultrafiltration of the electrodeposition liquid. Even if it is not provided, the variation in film thickness is small. Presumably, the water adhering to the substrate after pickling can be estimated to be relatively easily replaced with the electrodeposition liquid as compared with the case after chemical polishing.

On the other hand, after the chemical polishing treatment, a step of substituting water by physically hitting the substrate surface wet with the washing water according to the present invention with an electrodeposition liquid or a filtrate obtained by ultrafiltration of the electrodeposition liquid is used. In Comparative Examples 3 and 4 which were not provided, the variation in the film thickness of the photoresist was large enough to be visually discernable.
Further, the undeveloped portion in the case of Comparative Example 3 of the substrate after exposure and development and the exposed portion in Comparative Example 4 did not show the residual development as seen in Comparative Examples 1 and 2. Reflecting variations in film thickness, overexposure and underexposure occur depending on the location,
The resist pattern became thick or thin. As a result, the shape of the resist pattern was significantly inferior to the cases of Examples 1 to 6, and the resolution was low at 100 μm or more. Further, in the case of Comparative Example 4, there were many places where the resist was not formed inside the through hole.

On the other hand, in Examples 1 to 6, the film thickness of the photoresist was extremely uniform and the appearance of the coating film was glossy and good. As a result, the resist pattern after exposure and development had a high resolution of 50 μm and a sharp shape. Of course, no residual development was observed. Further, in the cases of Examples 5 and 6, the resist was uniformly formed inside the through holes.

[0102]

According to the present invention, the electrodeposition film (photoresist) after electrodeposition coating is uniformly formed without being influenced by the surface of the substrate, and in the case of a substrate having a through hole, a through hole is formed. A resist is uniformly formed to the inside without defects, and by exposing and developing the resist, a sharp high-resolution resist pattern can be obtained. The present invention is particularly effective for manufacturing a printed circuit board.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuro Kato 4-13-1, Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Factory (72) Inventor Shigeo Tachiki 4-13, Higashimachi, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Chemical Co., Ltd. in Ibaraki Research Laboratory (72) Inventor Shoji Yamada 1382-12 Shimoishigami, Otawara-shi, Tochigi Dainippon Paint Co., Ltd. Nasu Plant (72) Inventor Toshihiko Shioya 1382 Shimoishigami, Otawara, Tochigi Prefecture No. 12 Dainippon Paint Co., Ltd.Nasu Factory (72) Inventor Victory Itani 580 Fujioka, Shizuoka Prefecture Tokai Denki Kogyo Yoshihara Factory (72) Inventor Yujiro Sano 580 Fujioka, Shizuoka Prefecture Tokai Denka Kogyo Co., Ltd. Yoshihara factory

Claims (5)

[Claims] 1. A substrate having a copper layer on its surface is subjected to a surface treatment using a chemical polishing liquid and washed with water, and then an electrodeposition liquid containing a photoresist component or a filtrate obtained by ultrafiltration of the electrodeposition liquid is physically applied. A method for electrodeposition coating a photoresist, which comprises applying a liquid film on the surface of the substrate to an electrodeposition solution or a filtrate obtained by ultrafiltration of the electrodeposition solution, and then performing electrodeposition coating. 2. A method of electrodeposition coating a photoresist according to claim 1, wherein the chemical polishing liquid is a liquid containing sulfuric acid and hydrogen peroxide or a liquid containing persulfate. 3. In a surface treatment using a chemical polishing liquid,
3. The method of electrodeposition coating a photoresist according to claim 1, wherein the polishing amount of the copper layer on the surface of the substrate is 0.5 μm or more. 4. A method of physically applying an electrodeposition liquid containing a photoresist component or a filtrate obtained by ultrafiltration of this electrodeposition liquid onto a substrate is a method of applying an electrodeposition liquid or a filtrate obtained by ultrafiltration of this electrodeposition liquid to a substrate. The electrodeposition solution, or the electrodeposition solution or the filtrate obtained by ultrafiltration of the electrodeposition solution is rubbed on the surface of the substrate with a roll or brush, etc., the electrodeposition solution or the filtrate obtained by ultrafiltration of the electrodeposition solution into the filtrate. A method of immersing a substrate and blowing the liquid toward the substrate in the liquid;
And at least one method selected from the group consisting of immersing a substrate in an electrodeposition solution or a filtrate obtained by ultrafiltration of this electrodeposition solution, and rubbing the surface of the substrate with a roll, a brush or the like in the solution. A method of electrodeposition coating a photoresist according to claim 1, 2 or 3. 5. A method for producing a resist pattern, which comprises forming a photoresist on a substrate by the electrodeposition coating method according to claim 1, 2, 3 or 4, and then exposing and developing imagewise.