JP2000098630A - Pattern forming method with water-soluble photoresist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a resist pattern capable of withstanding high-speed etching conditions with a chromium-free water-soluble photoresist composition. SOLUTION: The water-soluble photoresist composition containing casein, a water-soluble azido compound and calcium salt of an organic acid is applied to a substrate such as a metallic sheet to form an etching resistant resist film. This resist film is selectively exposed through a prescribed mask pattern and the unexposed part is removed by development with water. The remaining resist pattern is hardened by contact with or dipping in an aqueous solution of tannic acid, the excess tannic acid is removed by washing and the etching resistance of the resist film is enhanced by heating after dehydrating or drying to form the objective resist pattern.

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 a pattern using a water-soluble photoresist composition required for mass-producing shadow masks, IC lead frames, fluorescent display tube meshes and the like of a color cathode ray tube by a photoetching method. . In particular, a pattern forming method using a water-soluble photoresist composition which does not use dichromate as a photosensitive agent and hexavalent chromium such as chromic anhydride as a hardener, has improved etching resistance, and can withstand high-speed etching It is about.

[0002]

2. Description of the Related Art A shadow mask used for a color cathode ray tube is usually manufactured by the following method. That is, as a substrate, aluminum killed steel (hereinafter referred to as AK material) having a thickness of 25 μm to 0.3 mm or nickel 3 having a small coefficient of thermal expansion is used.
6% amber-type iron alloy (hereinafter referred to as amber material)
The surface is treated by degreasing and washing with water, and then the surface is coated with a water-soluble photoresist, dried, and formed into a film.
Next, a mask pattern having a target image is adhered to a portion corresponding to the electron beam passage hole on the substrate, and the substrate is exposed to ultraviolet light. After undergoing a development hardening process and a heat treatment process, a predetermined pattern of a corrosion resistant film (hereinafter referred to as a resist film) is formed. ) Is formed on a substrate. Then, a metal part without a resist film is etched with an etchant such as a ferric chloride solution to form a large number of electron beam passage holes, and then an alkaline aqueous solution (for example, 5 to 20 wt. %
(Aqueous sodium hydroxide solution) to form a shadow mask. In addition, electronic parts such as IC lead frames, fluorescent display tube meshes, printed wiring boards, and the like are manufactured using a pure copper, copper alloy, iron material, 42Ni-iron alloy (hereinafter referred to as 42 alloy), stainless steel, etc. as a substrate, and a shadow mask is manufactured. It is manufactured through the same process as.

[0003] Photoresist (hereinafter referred to as resist)
For example, an aqueous solution of a water-soluble polymer such as casein or polyvinyl alcohol is mixed with an aqueous solution of ammonium bichromate in an amount of 3 to 15 for its advantages such as being inexpensive, not flammable, and capable of performing water treatment in all steps. A water-soluble negative type etching resist which is photosensitive by adding weight% is used. In addition, since these etching resists use a dichromate such as ammonium bichromate as a photosensitive agent and chromic anhydride as a hardener,
A tough resist film can be formed. Therefore, the resist film can be mass-produced by a photo-etching method under high-speed etching conditions (for example, 45 ° Be ′ ferric chloride solution, 8
0 ° C. for 20 minutes). However, hexavalent chromium contained in the processing waste liquid is a harmful substance,
Wastewater standards are also strictly regulated.

As a water-soluble resist not using hexavalent chromium (hereinafter referred to as a “chromium-free water-soluble resist”),
For example, Japanese Patent Publication No. 41-7100, U.S. Pat.
No. 26, JP-A-7-244374 discloses a photosensitive composition containing casein and an azide compound.
No. 41, JP-B-57-6098 and the like propose a water-soluble resist containing polyvinyl alcohol and a diazo resin, and a hardener and a processing method therefor. In addition, Tokubo Sho 5
JP-A-10-3107 discloses a water-soluble resist containing a water-soluble acrylic synthetic resin having an ethylenically unsaturated bond in a side chain and an anthraquinone sulfonate and / or a water-soluble azide compound. Have proposed a water-soluble photosensitive composition containing polyvinyl alcohol having an ethylenically unsaturated bond in the side chain and a photopolymerization initiator, etc., but any of them is practical because the resist film is destroyed under high-speed etching conditions. It has not been reached yet.

[0005]

However, even in this field in which electronic parts such as shadow masks and lead frames are mass-produced by the photo-etching method, a casein-based compound having practical sensitivity, resolution and etching resistance is used. Chromium etching resist is strongly desired. In order to solve these problems, it has been proposed to improve sensitivity, resolution and etching resistance by using a water-soluble resist composition containing casein, a water-soluble azide compound and a calcium salt of an organic acid ( Japanese Patent Application No. 9-28738
No. 3). This no-chromium water-soluble resist composition can be practically used for its sensitivity and resolution, but it is necessary to heat cure (post-bake) the resist film after development at 250 ° C. for 10 minutes in order to impart etching resistance. . However, it has been found that post-baking under these conditions causes oxidation or expansion and contraction depending on the type of the substrate material, and also has a problem that the etching resistance of the resist varies. Therefore, the post-baking condition is further reduced to a lower temperature (for example, 200 ° C. for 10 minutes).
Therefore, there has been a strong demand for a method of forming a resist film that can be performed in a low temperature and stably withstands high-speed etching conditions.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, developed using water having an appropriate hardness, and further developed an aqueous solution of tannic acid having an appropriate concentration. By using it as a liquid, the casein resist film was found to be extremely hardened, and a method of forming a pattern of a water-soluble photoresist composition that satisfies the above-mentioned problem was obtained. It was completed.

Accordingly, the present invention provides a resist coating formed by exposing a coating of a water-soluble photoresist composition containing casein, a water-soluble azide compound and a calcium salt of an organic acid, and then developing the coating with water having a specific hardness. And a method of forming a resist film with enhanced etching resistance, characterized in that the resist film is treated with an aqueous solution of tannic acid having a specific concentration.

More specifically, an object of the present invention is to apply a water-soluble resist composition containing casein, a water-soluble azide compound and a calcium salt of an organic acid to a substrate such as a thin metal plate and etch-resist a resist. After forming a film, selectively exposing it to ultraviolet rays or the like via a predetermined mask pattern, and removing the resist film in an unexposed portion other than the pattern portion formed by exposure by aqueous development, the obtained resist pattern is subjected to tanning. Forming a pattern characterized by hardening by contacting or dipping in an aqueous solution of an acid, washing and removing excess tannic acid, draining or drying, and then heating to enhance the etching resistance of the resist film; It is to provide a method.

[0009] The developer used in the present invention is prepared by reducing the amount of Ca ions and / or Mg ions contained in the developer to CaCO
_It is preferable to use water having a hardness in the range of 15 to 200 mg / l in terms of _three amounts (hereinafter referred to as water having a hardness of 15 to 200). The tannic acid aqueous solution as a hardening solution varies depending on the water-soluble resist composition. However, by using an aqueous solution having a tannic acid concentration in the range of 0.3 to 1.5% by weight, the no-chrome resist film can be etched at a high speed. Since the film hardens hard enough to withstand the conditions, a concentration in this range is preferable.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The water-soluble resist composition used in the present invention is a water-soluble photosensitive composition containing an aqueous casein solution containing a water-soluble azide compound as a photocrosslinking agent and a calcium salt of an organic acid serving as a sensitizer. The composition is an acidic composition. Examples of the water-soluble azide compound include 4,4'-diazidostilbene-2,2'-disulfonate (sodium salt and potassium salt, tetramethylammonium salt and the like),
4,4'-diazidobenzalacetone-2,2'-disulfonate, 6-azido-2- (4'-azidostyryl) benzimidazole and 4-azidobenzaldehyde in a copolymer of dimethylacrylamide and diacetoneacrylamide And high molecular azide compounds obtained by condensing -2-sulfonic acid salts. Two or more azide compounds may be used as a mixture in view of the solubility in water and the photosensitive wavelength spectrum of the light source. The water-soluble azide compound is usually added and dissolved in an amount of 1 to 15 parts by weight based on 100 parts by weight of casein.

As the calcium salt of an organic acid, a compound which can be dissolved or dispersed in water or added or dissolved in an aqueous solution of casein and which does not inhibit photosensitivity can be used. Specifically, calcium glycolate, calcium gluconate, calcium acetate, calcium L-aspartate,
Examples include calcium glycerophosphate, calcium lactate, calcium formate, calcium L-glutamate, calcium pantothenate, calcium ascorbate, calcium xanthate, and the like. The calcium salts of organic acids may be used alone or in combination of two or more. The amount is 0.1 to 2 parts per 100 parts by weight of casein.
Used in an amount of 0 parts by weight.

The casein component used in the present invention includes:
Acid casein, sodium caseinate, calcium caseinate and the like can be used.In particular, acid casein can be used in terms of stability, such as ammonia, amines such as triethylamine, and inorganic alkali agents such as borax, sodium carbonate, and sodium hydroxide. An aqueous solution of casein dissolved in water containing water or the like is preferably used. These are, for example, trade names "FR-1"
5, "FR-16", "FR-17" (all manufactured by Fuji Pharmaceutical Co., Ltd.), "MR-SLG", "MR-
It is commercially available as "SMG" and "MR-SG" (both manufactured by The Inktech Co., Ltd.) and is commercially available.

The no-chromium water-soluble resist composition used in the present invention comprises a water-soluble photosensitive composition containing casein, a water-soluble azide compound, and a calcium salt of an organic acid. Commonly used antiseptic / antifungal agents, coloring materials, plasticizers, crosslinking agents, antifoggants, adhesion promoters and the like may be used in combination.

As the substrate in the present invention, those generally used in this field can be used, for example, iron (AK material), iron nickel alloy (amber material, 42 alloy), copper, copper alloy,
A plate of stainless steel or the like may be used. Although the substrate is not particularly limited, it is used as it is with a coil having a plate thickness of 0.05 to 0.5 mm or after a cut plate is degreased using an alkaline degreaser, washed with water and dried. Thereafter, the prepared no-chromium water-soluble resist composition is degassed by mesh filtration or allowed to stand naturally and then defoamed on one or both surfaces of the substrate by, for example, 3 to 10 μm by dip-and-pull coating and pouring application. Apply to a film thickness of about 60 to 1
Dry with hot air at 00C for 5 to 10 minutes to form a resist film. Thereafter, a mask pattern such as a shadow mask or a lead frame is brought into close contact with the resist film surface on the substrate, and exposure is performed using a light source such as an ultra-high pressure mercury lamp or a metal halide lamp.

As the developer, it is preferable to use water having a hardness of 15 to 200. Further, it is particularly preferable to use water having a hardness of 30 to 150 for the developer. Developing with water having a hardness within these ranges can form a resist film that can withstand higher-speed etching conditions than using pure water as a developer. However, when development is performed with water having a hardness of 200 or more, development residues often occur. The water development is preferably carried out with hot shower water of 20 to 45 ° C.

Since the water-developed resist film is still soft, it is immersed in or brought into contact with an aqueous solution of tannic acid, and after hardening, excess tannic acid is washed with water. The tannic acid is preferably
The standard is “pharmacological tannic acid” or “special tannic acid” commercially available from Dainippon Pharmaceutical Co., Ltd. The concentration of the tannic acid aqueous solution used preferably contains tannic acid in the range of 0.3 to 1.5% by weight. Especially 0.4 ~
An aqueous solution containing tannic acid in the range of 1.0% by weight is preferred. When the content is less than 0.3% by weight, the hardening property is weak.
If the amount is more than 10% by weight, the resist film shrinks and may not endure high-speed etching conditions. The temperature of the processing solution is 15 ~ 3
Preferably, the immersion or contact time at 0 ° C. is 5 seconds to 2 minutes. The pH of the tannic acid aqueous solution is preferably from 3 to 4.5, since the metal substrate and the like are not corroded and the hardening effect of the resist film is good. Further, a reducing agent or a surfactant such as oxalic acid, ascorbic acid or DL-sorbite can be added to the aqueous solution of tannic acid within this pH range. Post-baking after hardening with tannic acid includes a heating treatment using an infrared heater or hot air, but hot air is preferable in order to uniformly impart heat and fix the resist film with heat. The temperature is 18
It is preferred to heat at 0-230 ° C for 5-15 minutes.

The resist pattern obtained by developing, hardening, and heat-fixing the no-chromium water-soluble resist used in the present invention under the above conditions can withstand the minimum condition of high-speed etching. The minimum condition for withstanding high-speed etching is that a substrate on which a resist pattern is formed is subjected to 45 ° Be ′ ferric chloride solution (hereinafter referred to as an aqueous solution of about 44% by weight of ferric chloride having a specific gravity of 45 ° Baume). This refers to a state in which the resist film is not broken and peeled off when immersed at 80 ° C. for 20 minutes and washed with water, and there is no surface roughness. The resist film having enhanced etching resistance according to the present invention can withstand high-speed etching conditions, and can be easily peeled off after use with a 5 to 20% by weight aqueous solution of caustic soda heated to 50 to 95 ° C.

In Japanese Patent Publication No. 56-20541, a water-soluble resist film based on polyvinyl alcohol can be used as a hardener by using an aqueous solution containing iodine and tannic acid and containing a salt of iron, molybdenum or tungsten. Has been described. However, when this hardener is used, although a hardening effect is observed, the no-chromium casein resist is iodinated and changes its color from brown to black, corrodes the substrate, and is still under high-speed etching conditions. There was a problem that it could not stand.

[0019]

The present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 Casein aqueous solution ("FR-17" Fuji Pharma Co., Ltd.)
0.6 g of calcium glycolate, 10 g of purified water and 0.36 g of sodium 4,4'-diazidostilbene-2,2'-disulfonate as a photosensitizer were dissolved in 100 g of casein (containing 12.03% by weight of casein). did. This solution was filtered and defoamed at the same time as filtering to prepare an aqueous solution of a chromium-free water-soluble resist composition. 0.3m thick
m alloy 42 was immersed in a 3% aqueous solution of “Jusco Clean No. 5” (manufactured by Japan Surface Treatment Co., Ltd.) at 70 ° C. for 5 minutes, degreased with alkali, washed with water, and dried to obtain a substrate. The prepared aqueous solution of the resist composition was applied to the degreased 42-alloy plate using a wheeler to a film thickness of 6 to 7 μm, and dried (prebaked) at 80 ° C. for 10 minutes in a hot-air constant-temperature drier.

Toppan Printing Co., Ltd. on the formed resist film
Resolution Chart and Kodak Photographic Step Table
The light having a wavelength of 300 nm or more was exposed at an amount of 400 mJ / cm ² using an ultra-high pressure mercury lamp while bringing t No. 2 (hereinafter referred to as a gray scale) into close contact with a vacuum. Next, the film was developed by immersion in water having a hardness of 80 to 90 for 30 seconds at room temperature (20 to 23 ° C.), washed with water, immersed in a 0.5% by weight aqueous solution of tannic acid for 30 seconds at room temperature, washed with water, and dried with a dryer.

This hardened resist film is heated at 200 ° C.
Post-baked for 10 minutes in a hot air oven. The sensitivity of this resist is 4.5 steps for the rest of the gray scale (hereinafter referred to as 4.5 steps of gray scale sensitivity. In order to increase the gray scale sensitivity by 2 steps, double exposure is required).
And high sensitivity. As for the resolution, there is no fringe of the film remaining due to the trailing of the unexposed portion, and a pattern in which the line width of the line and space pattern in the resolution chart is 15 μm (hereinafter referred to as 15 μm L / S) is resolved. It had been. The color of the resist film after post-baking was pale yellow, and the color of the resist film after development and tannic acid treatment was hardly changed. Further, no corrosion of the substrate after the tannic acid treatment was observed. The substrate having the resist pattern (42 alloy plate) was immersed in a 45 ° Be ′ ferric chloride solution at 80 ° C. for 20 minutes to observe the surface of the resist film, but there was no surface roughness and no peeling due to swelling of the film. It was confirmed that the resist film could withstand the minimum condition of high-speed etching. Table 1 shows the results.

Comparative Example 1 When a resist pattern was formed in the same manner as in Example 1 using the no-chromium water-soluble resist composition used in Example 1, the resist was developed using purified water having a hardness of 10 or less as a developing solution. And the etching resistance at 80 ° C. for 20 minutes. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 Using the no-chromium water-soluble resist composition used in Example 1 and forming a resist pattern in exactly the same manner as in Example 1, a 0.5% by weight tannic acid aqueous solution was used instead of a 0.5% by weight aqueous solution. 9 g of potassium iodide, 3 g of iodine, and ferrous sulfate 20 described in JP-B-56-20541.
g, 20 g of tannic acid, 1000 ml of tap water, sensitivity, discoloration of resist film and corrosion state of substrate, and etching resistance of resist film after 20 minutes at 80 ° C. Was. Table 1 shows the results.

[0025]

[Table 1] From the results shown in Table 1, it can be seen that the resist film can withstand high-speed etching if the method for forming a pattern of a chromium-free water-soluble resist according to the present invention is performed.

Example 2 When a resist pattern was formed in exactly the same manner as in Example 1 using the no-chromium water-soluble resist composition used in Example 1, the developer was replaced with a water having a hardness of 80 to 90 instead of water having a hardness of 80 to 90. When immersion development was performed at room temperature using water of 140 to 150, it took 45 seconds for unexposed portions to be dissolved and removed. At this time, the gray scale sensitivity was 5 steps, slightly higher than that of Example 1. Further, the resolution was such that there was no residual film in the unexposed portion, and the L / S of 15 μm was resolved in the resolution chart. Exactly as in Example 1,
A 42 alloy plate having a resist pattern hardened with an aqueous solution of tannic acid and post-baked is immersed in a 45 ° Be ′ ferric chloride solution at 80 ° C. for 20 minutes and washed with water to completely remove the resist film. I was enduring.

[0027]

According to the method for forming a pattern of a water-soluble photoresist of the present invention, it is possible to obtain a resist film that can withstand high-speed etching conditions using a chromium-free water-soluble photoresist composition. Therefore, the present invention can be suitably used for mass production of a shadow mask of a color cathode ray tube, an IC lead frame, a mesh of a fluorescent display tube, and the like by a photo-etching method.

Continued on front page F term (reference) 2H025 AA07 AB06 AC01 AD01 BA06 EA04 FA01 FA17 FA29 FA31 FA48 2H096 AA19 BA02 CA14 DA01 EA02 GA08 GA25 HA01 HA18 5F046 AA02 CA02 JA01 JA04 KA01 LA09 LA19 MA02

Claims (4)

[Claims] 1. A resist film formed by a water-soluble photoresist composition containing casein, a water-soluble azide compound and a calcium salt of an organic acid, is developed with an aqueous developer and treated with an aqueous solution of tannic acid. A method for forming a resist pattern with enhanced etching resistance. 2. An etching-resistant resist film is formed by applying a water-soluble photoresist composition containing casein, a water-soluble azide compound and a calcium salt of an organic acid to a substrate such as a thin metal plate, and forming a predetermined mask pattern. After selectively exposing through an unexposed portion and developing and removing the unexposed portion with water, the remaining resist pattern is contacted or immersed in an aqueous solution of tannic acid to form a hardened film, and excess tannic acid is washed away with water,
2. The method for forming a resist pattern according to claim 1, wherein the resist film is dried or dried and then heated to enhance the etching resistance of the resist film. 3. The method according to claim 1, wherein water of the developing solution contains Ca contained in the developing solution.
_{3. The} method according to claim 1, wherein the water is water having a hardness in the range of 15 to 200 mg / l in terms of the amount of ions and / or Mg ions converted to the amount of CaCO3. 4. A tannic acid aqueous solution having a tannic acid concentration of 0.3 to 1.5% by weight.
Or the method of forming a resist pattern according to 2.