JPH0720640A - Method for hardening film of water-soluble photoresist - Google Patents

Abstract

PURPOSE:To obtain a resist film which is not chipped even if the etching time is increased and has the etching resistance and adhesion to a substrate improved even if the burning time is prolonged by hardening the film of a water-soluble photoresist. CONSTITUTION:A substrate 28 is developed in a developing section 14, then dipped in a hardening soln. 36, washed with water in a washing section 18, drained in a draining section 20 and heat-treated in a burning section 22. When the substrate 28 is heat-treated, moisture is supplied to heat-treating chambers 46 and 50 in addition to the moisture contained in a water-soluble photoresist film on the substrate surface and entrained into the heat-treating chambers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention hardens a water-soluble photoresist that has been subjected to a development treatment applied on the surface of a metal substrate in a series of steps for manufacturing a substrate such as a shadow mask for a color CRT by a photoetching method. The present invention relates to a method for treating a membrane.

[0002]

2. Description of the Related Art A series of steps in a photoetching method will be described by taking a case of manufacturing a shadow mask as an example.

The shadow mask is generally manufactured in large quantities and continuously, and the shadow mask material is sent from the steel plate manufacturer to the shadow mask manufacturer in the form of a coil having a weight of 1 to 2 tons. In general, the shadow mask material fed from the coil is subjected to various treatments in a long strip shape, and after the series of steps of photoetching is finished, the long strip is cut into a single-wafer form.

First, it has a long strip shape and a plate thickness of 0.05 to
Degrease the shadow mask material such as 0.3 mm low carbon aluminum killed steel or Invar type alloy containing 36% nickel, remove the rust preventive oil on the surface, wash with water, and then use an acidic solution or alkaline solution to prepare. Surface treatment and washing with water (surface preparation step). Next, a photosensitive solution, for example, a photosensitive solution containing casein and dichromate is applied to both the front and back surfaces of the shadow mask material, and dried to form a photoresist film having a thickness of several μm on the front and back surfaces of the shadow mask material. Are deposited (coating step). Next, on the surface of each photoresist film deposited on both the front and back sides of the shadow mask material, form each master pattern having a required image corresponding to the electron beam passage hole to be formed on the front side and the back side. Are aligned and brought into close contact with each other, and exposure is performed (baking step). Subsequently, the photoresist film is developed using warm water or the like, the shadow mask material is dipped in a hardening liquid, for example, a chromic anhydride solution, and then burned by hot air or an infrared heater at a temperature of 220 to 280 ° C. By performing (heat treatment), a resist film having a desired pattern image is formed on both main surfaces of the shadow mask material (developing step). A ferric chloride aqueous solution is used to perform spray etching on both main surfaces of the shadow mask material to form a large number of through holes, and then the resist film is peeled off from both surfaces of the shadow mask material (etching step). Finally,
The shadow mask material is cut to obtain a sheet-shaped shadow mask (shearing step).

In the above series of photo-etching processes, the burning treatment after the shadow mask material is immersed in the hardening liquid after the development treatment is to cure the unreacted casein and to improve the corrosion resistance of the resist film during etching. Is to improve. As a method of this dura treatment,
For example, in JP-A-57-148859, after development, a chromic anhydride solution or a dichromate solution is applied to the surface of a photoresist film by dipping or spraying, followed by washing with water, substituting water with alcohol, and drying. After that, a method of applying a burning treatment is disclosed. Also,
In Japanese Patent Publication No. 3-62264, the exposed water-soluble photoresist is washed with water, developed, and then drained by a squeezing roller or an air knife, and then the water-soluble photoresist is immersed in an aqueous chromic anhydride solution. Before and after this immersion, a chromic anhydride aqueous solution is sprayed onto the water-soluble photoresist by a spray method or a shower method, and then the water-soluble photoresist is washed with water,
A method is disclosed in which after washing, water is removed with a squeezing roll, water is further removed with a hot air type air knife, and then the water-soluble photoresist is burned. In these methods, hexavalent chromium of chromic anhydride or dichromate is reduced to trivalent chromium by burning, and a cross-linking reaction by the bond between the reduced trivalent chromium and casein produces a water-soluble photochromic compound. I try to harden the resist.

[0006]

By the way, in recent years, color CRTs are required to have a large screen, high brightness and high definition. The shadow mask used in such a color CRT tends to have a large thickness in order to prevent image shake due to thermal expansion and vibration during use of the CRT. As the plate thickness of the shadow mask increases, the time required for etching the shadow mask material in manufacturing the shadow mask increases. Here, in the production of the shadow mask, a photosensitive liquid consisting of casein and dichromate is generally used. However, when the etching time of the shadow mask material becomes long, the surface of the shadow mask material is coated with the photosensitive liquid. There is a problem that the deposited resist film cannot withstand etching for a long time. That is, as shown in a partially enlarged cross-sectional view of FIG. 2, a part of the resist film 2 is etched while etching the shadow mask material 1 in which resist films 2 and 3 having a desired pattern image are deposited on both main surfaces. If the chip 4 has a chip 4 and etching is continued as it is, the shadow mask material 1 in the part having the chip 4 is excessively etched to form a through hole 5 larger than a normal through hole indicated by a chain double-dashed line. Therefore, there is a problem that the shadow mask becomes defective.

The cause of chipping of the resist film is considered to be that the resist becomes too hard due to thermal denaturation of casein during burning, and the resist film becomes rather brittle. Therefore, as a countermeasure against this, it is conceivable to lower the burning temperature so as not to cause thermal denaturation of casein, which actually reduces the occurrence of chipping of the resist film. However, when the burning temperature is lowered, chromium in the dichromate is not completely reduced from hexavalent to trivalent during burning,
Insufficient cross-linking between chromium and casein. As a result,
A new problem that the resist film dissolves in the etching solution during etching, the adhesion between the resist film and the shadow mask material deteriorates, and the through holes formed in the shadow mask material by etching become large. Will occur.

In this case, even if the burning temperature is lowered, it is possible to completely reduce hexavalent chromium to trivalent chromium by prolonging the burning time. However,
For example, in the case of performing burning with hot air, burning at a temperature of 240 ° C. for 2 minutes can reduce trivalent chromium, whereas burning at a temperature of 200 ° C. that does not cause chipping of the resist film during etching can be performed. If this is done, the processing will take more than 10 minutes. As described above, the method of lowering the burning temperature is not practically applicable because the productivity is greatly reduced.

The present invention has been made in view of the above circumstances, and even if the etching time is long, the resist film is not chipped during the etching, and the burning time is long. It is an object of the present invention to provide a method of hardening a water-soluble photoresist, which can form a resist film having good etching resistance and adhesion to a metal substrate without performing the above.

[0010]

The invention according to claim 1 is
After immersing the substrate on which the water-soluble photoresist film that has finished the development treatment on the surface is immersed in the hardening liquid or spraying or dripping the hardening liquid on the substrate, washing with water, and then draining, In a method of hardening a water-soluble photoresist for carrying a substrate to a heat treatment chamber and subjecting the substrate to heat treatment, in the heat treatment chamber, the water-soluble photoresist film deposited on the substrate surface is Water is supplied separately from the water contained and brought into the heat treatment chamber.

According to a second aspect of the present invention, in the method for hardening a water-soluble photoresist film according to the first aspect, water vapor is supplied into the heat treatment chamber.

According to a third aspect of the present invention, in the method for hardening a film of a water-soluble photoresist according to the first aspect, water is supplied to the evaporation dish arranged in the heat treatment chamber.

According to a fourth aspect of the present invention, in the method for hardening a film of a water-soluble photoresist, the substrate is immersed in water at least once during the heat treatment of the substrate and then drained. Is characterized by.

[0014]

According to the experiments conducted by the present inventors, after immersing the water-soluble photoresist film in the chromic anhydride aqueous solution,
It was found that when the water content of the photoresist film is evaporated by the heat treatment, the reaction rate of reducing hexavalent chromium in the photoresist to trivalent chromium becomes slow.

In the dura mating method according to the present invention described above,
When the substrate is heat-treated in the heat treatment chamber after being rinsed and drained by immersing the substrate in the hardener or spraying the substrate with the hardener, moisture is supplied from the outside into the heat treatment chamber. At this time, water vapor is supplied into the heat treatment chamber, or water is supplied to the evaporation dish arranged in the heat treatment chamber. Further, in the film-hardening method according to another aspect of the present invention, the substrate is immersed in water while the substrate is being heat-treated, or water is sprayed on or dripped onto the substrate and then drained off to form a photoresist film. The heat treatment is performed in a state where the water contains water. As a result, when, for example, a chromic anhydride aqueous solution is used as the hardening liquid, the chromic anhydride 6 permeated into the photoresist film is
The reaction in which valent chromium is reduced to trivalent chromium is promoted.
Therefore, the hexavalent chromium is sufficiently reduced to the trivalent chromium even at the low temperature at which the chipping of the resist film does not occur during etching and even when the burning is performed without increasing the processing time. As a result, a resist film having good etching resistance and good adhesion to a metal substrate is formed.

For example, in the case of performing burning with hot air, at a temperature of 200 ° C. in which the resist film is not chipped during etching, when water is not supplied to the photoresist film during the process, it is hexavalent. It takes more than 10 minutes before chromium is reduced and disappears. On the other hand, after the burning treatment was performed at a temperature of 200 ° C. for 2 minutes, the substrate was immersed in water at a temperature of 40 ° C.
When soaking for 0 seconds, the hexavalent chromium is almost completely reduced to trivalent chromium only by performing a burning treatment at a temperature of 200 ° C. for 2 minutes.

[0017]

The preferred embodiments of the present invention will be described below.

FIG. 1 is an example in which the present invention is applied to a manufacturing process of a shadow mask, and is a schematic diagram showing an example of the structure of a developing / hardening processing apparatus for carrying out the film hardening method according to the present invention. It is a figure. This apparatus includes a long strip shadow mask material (substrate) supply unit 10, an accumulator 12, a development processing unit 14, a hardener supply unit 16, a water washing unit 18, a water draining unit 20, a burning processing unit 22, and a shadow mask material. It is composed of a winding section 24.

In the shadow mask material supplying section 10, a substrate having a surface coated with a water-soluble photoresist film after baking is held in the form of a coil 26, and a substrate 28 is continuously fed from the coil 26. It is supposed to be. The substrate 28 delivered from the shadow mask material supply unit 10 is adjusted by the accumulator 12 such that the timing of conveyance is adjusted and the tension is kept constant. The development processing section 14 is provided with a developing tank 30, a substrate 28 is introduced into the developing tank 30, and the substrate 28 is a developing tank.
While passing through the inside of the substrate 30, hot water, for example 40 ° C. hot water, is sprayed onto both main surfaces of the substrate 28 from a plurality of spray nozzles 32 lined up on both sides of the substrate 28 along the transfer path,
It is developed. The hardening fluid supply unit 16 is provided with a hardening solution, for example, a hardening solution tank 34 containing a chromic anhydride aqueous solution 36. The substrate 28 is adapted to be immersed. Further, a pair of shower nozzles 38 are arranged above the hardening solution tank 34 so as to sandwich the transfer path of the substrate 28, and a pair of shower nozzles 38 are placed in the hardening solution tank 34 into the chromic anhydride solution 36. Prior to dipping 28, a chromic anhydride aqueous solution is sprayed from a pair of shower nozzles 38 onto both main surfaces of substrate 28. As a means for supplying the hardening liquid to the substrate, the dipping method and the coating method applied from the shower nozzle are used together in the illustrated example, but the hardening liquid is applied to the substrate by only one of the methods. You may supply it, or
A spray method may be used.

A water washing tank 40 is disposed in the water washing section 18, and a plurality of spray nozzles 42 are lined up on both sides of the water washing tank 40 along the transfer path of the substrate 28. While the substrate 28 is passing through the washing tank 40, hot water, for example 40 ° C., is applied to both main surfaces from the plurality of spray nozzles 42.
It is washed by being sprayed with warm water. A pair of squeezing rollers 44 are arranged at the outlet of the washing tank 40, and the substrate 28 after washing is drained in the draining section 20. Incidentally, a pair of air knives may be arranged in parallel in the water draining section 20 on the rear side of the squeezing roller 44 in the transport direction, and as a water draining means, a squeegee of the surface of the substrate may be formed by a film or a rubber plate. You may make it employ | adopt a system.

The burning processing unit 22 includes a first burning chamber 46, a hot water tank 48, a second burning chamber 50,
It is composed of steam supply means 52 and water supply means 54. Inside each of the first and second burning chambers 46, 50, a plurality of infrared heaters 56 are arranged in a row along the transfer path of the substrate 28 on both sides thereof. Then, while the substrate 28 passes through the respective burning chambers 46 and 50, the substrate 28 is heated to about 200 ° C., respectively.
It should be noted that hot air may be used to heat the substrate, or an induction heating method may be used.

Hot water in the hot water tank 48, for example, hot water at 40 ° C.
58 (room temperature water may be used, but warm water is preferable because it has better permeability of moisture into the photoresist film and can shorten the processing time). By immersing the substrate 28 in the warm water 58 in the warm water tank 48, water is supplied to the photoresist film. Instead of immersing the substrate 28 in the warm water 58, water may be supplied to the substrate by a spray method, a shower method, or the like. A pair of squeezing rollers 60 are arranged at the outlet of the hot water tank 48, and the substrate after being immersed in water by the pair of squeezing rollers 60.
Draining of 28 is performed, after which the substrate 28 is pumped into the second burning chamber 50. Water vapor supply means 52
Is composed of a steam generating boiler 62 and a steam pipe 64, and supplies the steam generated in the boiler 62 into the first burning chamber 46 through the steam pipe 64. Further, the water supply means 54 includes a water tank 66, a pump 68, and a water supply pipe.
It is composed of 70 and an evaporating dish 72, and supplies water from the water tank 66 to the evaporating dish 72 installed in the first burning chamber 46 from the water tank 66 by the pump 68. The water supplied to the evaporation dish 72 is evaporated in the first burning chamber 46 by the heat of the infrared heater 56 to become water vapor.
In order to supply water into the first burning chamber 46, in the illustrated example, the steam supply means 52 and the water supply means 54
However, the water may be supplied into the first burning chamber 46 by only one of the means. Further, instead of providing the hot water tank 48, or by providing the hot water tank 48, water may be supplied into the second burning chamber 50 by the steam supply means or the water supply means.

The substrate 28 which has been subjected to the burning treatment in the burning treatment section 22 and the hardening treatment has finished passes through the driving roller 74,
The shadow mask material winding portion 24 is wound in the form of a coil 76. Reference numeral 78 in the drawing denotes a substrate carrying roller.

Using the developing / hardening device having the above-mentioned structure, the substrate 28 having the water-soluble photoresist film after baking adhered on both main surfaces is subjected to the developing process part 14 and the film hardening liquid supply part.
16, the washing unit 18, the draining unit 20, and the burning treatment unit 22 while sequentially transported, the water-soluble photoresist film deposited on both main surfaces of the substrate 28 is developed and hardened, and the required treatment is performed. A substrate having a resist film having a pattern image deposited on both main surfaces is obtained. Then, in this method, moisture is supplied from the outside into the first heat treatment chamber 46, and the substrate 28 is immersed in the hot water 58 before the substrate 28 is fed into the second heat treatment chamber 50. When the substrate 28 is heat treated in the two heat treatment chambers 46 and 50 after the substrate 28 that has been developed and then immersed in the chromic anhydride aqueous solution 36 and washed with water is drained, in which heat treatment chamber 46 or 50 Also, the heat treatment is performed in a state where the photoresist film contains water. As a result, the reduction reaction of chromic anhydride, which has penetrated into the water-soluble photoresist film on the surface of the substrate 28, from hexavalent chromium to trivalent chromium is promoted.
Even if the substrate 28 is heat-treated at a low temperature of about 200 ° C. in the temperature range of 6 and 50, the hexavalent chromium is sufficiently reduced to trivalent chromium, and the resist film has excellent etching resistance and adhesion to the substrate. Is obtained.

When the water is not drained after the substrate 28 is washed in the water washing section 18, and when the water is not drained after the substrate 28 is immersed in the hot water 58 in the hot water tank 48, the first During the burning process of the substrate 28 in the burning chamber 46 and the second burning chamber 50, the moisture distribution in the photoresist film is not uniform, so that the uniform hardening process cannot be performed, and the subsequent etching process is performed. At times, uneven etching is likely to occur. Therefore,
Before the substrate is carried into the first and second burning chambers 46, 50 after washing with water and immersion in water, the substrate 28 needs to be drained by the squeezing rollers 44, 60 and the like.

Examples of the water-soluble photoresist include milk casein, natural polymers such as fish glue, gelatin, and egg white, or synthetic polymers such as PVA (polyvinyl alcohol) and polyacrylamide, and dichromate. Diazonium salts, azide compounds, etc. added as sensitizers are generally used, but in order to improve the etching resistance of these water-soluble photoresists and the adhesion to the substrate, the photosensitivity after development is improved. The hardening treatment may be performed using a solution of chromic anhydride, dichromate, or tungstic acid, tungstate, molybdic acid, molybdate, or the like. These cases are also the same in that the crosslinking or coordination bond of the hardener and the thermosetting of the polymer compound are used, and the present invention can be applied similarly.

[0027]

Since the present invention is constructed and operates as described above, when the method for hardening the water-soluble photoresist is carried out by the method according to the present invention, even if the etching time becomes long. There is no occurrence of chipping of the resist film during etching, and without lengthening the burning time, it is possible to form a resist film having good etching resistance and adhesion to a metal substrate. It is possible to obtain a good shadow mask in which proper through holes are formed, and it is possible to maintain high productivity.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a case where the present invention is applied to a manufacturing process of a shadow mask, and showing an example of a configuration of a developing / hardening processing apparatus for carrying out a hardening treatment method according to the present invention. .

FIG. 2 is a diagram for explaining a problem in the conventional film-hardening method and is a partially enlarged cross-sectional view of a shadow mask material.

[Explanation of symbols]

 14 Development Processing Section 16 Hardening Solution Supply Section 18 Rinsing Section 20 Draining Section 22 Ultraviolet Irradiation Section 22 Burning Processing Section 28 Substrate 30 Developing Tank 32 Spray Nozzle 34 Hardening Solution Tank 36 Hardening Solution (Aqueous Chromic Acid Aqueous Solution) 38 Shower Nozzle 40 Water washing tank 42 Spray nozzle 44, 60 Squeeze roller 46, 50 Burning chamber 48 Hot water tank 52 Steam supply means 54 Water supply means 56 Infrared heater 58 Hot water 62 Boiler for steam generation 66 Water tank 72 Evaporating dish

Claims (4)

[Claims] 1. A substrate coated with a water-soluble photoresist film whose surface has been subjected to a development treatment is dipped in a hardening solution, or after the hardening solution is sprayed or drip-coated onto the substrate,
In a method of hardening a water-soluble photoresist, wherein the substrate is transferred into a heat treatment chamber and subjected to heat treatment after being rinsed with water and then drained, and a substrate surface is deposited in the heat treatment chamber. A method of hardening a water-soluble photoresist, characterized in that the water is supplied separately from the water contained in the water-soluble photoresist film and brought into the heat treatment chamber. 2. The method of hardening a water-soluble photoresist according to claim 1, wherein steam is supplied into the heat treatment chamber. 3. The method of hardening a water-soluble photoresist according to claim 1, wherein water is supplied to an evaporation dish arranged in the heat treatment chamber. 4. A substrate coated with a water-soluble photoresist film whose surface has been subjected to a development treatment is dipped in a hardening liquid, or after the hardening liquid is sprayed or drip-coated onto the substrate,
In a method of hardening a film of a water-soluble photoresist in which a substrate is transferred into a heat treatment chamber and subjected to heat treatment after being washed with water and then drained, at least during the heat treatment of the substrate. A method for hardening a water-soluble photoresist, which comprises immersing the substrate in water once, or spraying or dripping water onto the substrate, and then draining.