JPH11109651A - Method for hardening resist film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent uneven hardening of a resist film contg. casein and a dichromate and to keep fine holes formed in large numbers in the surface of the film uniform in diameter by specifying the concn. of chromic anhydride in a hardening soln. for hardening the resist film. SOLUTION: A hardening soln. contg. 0.2-0.4% chromic anhydride is fed to a metallic sheet with a resist film contg. casein and a dichromate and having a prescribed pattern formed on the principal surface to harden the resist film. When the resist film contains PVA and a dichromate, the concn. of chromic anhydride in the hardening soln. is regulated to 0.8 to <1.0%. Whether the pattern is a high definition pattern or not, a high quality resist film is obtd. The amt. of the dichromate used is reduced and load on the environment is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a series of processes for manufacturing a shadow mask for a color picture tube, an aperture grill for a Trinitron tube (registered trademark), a lead frame for a semiconductor device, and the like by a photoetching method. And a method for hardening a resist film having a predetermined pattern formed on a main surface of the resist film.

[0002]

2. Description of the Related Art In general, a shadow mask, an aperture grill, a lead frame and the like are manufactured by processing a long metal thin plate by using a photo etching method. To briefly explain a series of manufacturing processes of a shadow mask, while transporting a long metal sheet in the longitudinal direction,
A cleaning step of removing oil or the like adhering to the main surface of the metal sheet, a resist having a photosensitive property on the main surface of the cleaned metal sheet, for example, casein or polyvinyl alcohol (PV)
A) applying a resist containing a dichromate and drying the resist to form a resist film on the main surface of the metal sheet, and applying a resist to the resist film formed on the main surface of the metal sheet. A baking process of baking a pattern, a developing process of partially dissolving and removing a resist film on a main surface of a thin metal plate on which a predetermined pattern is baked according to a predetermined pattern, and a metal having a resist film having a predetermined pattern formed on a main surface thereof. A hardening solution, for example, a hardening solution containing chromic anhydride is supplied to the thin plate, followed by a burning (heating) treatment or the like to harden the resist film, and a hardening process of the main surface of the metal thin plate. Through an etching step of etching the exposed metal surface where the resist film is partially dissolved and removed to form a number of through holes, and then peeling the resist film from the main surface of the thin metal plate, In each of the processing steps, the metal sheet is subjected to a predetermined process to obtain a metal sheet with a large number of small through holes, which are used as electron beam passage holes, and then the long metal sheet is cut in the shearing step Then, a single-wafer form is obtained to obtain a shadow mask product.

In the above-described series of manufacturing processes, the hardening treatment of the resist film after the developing process is performed because the resist film which has been developed is not sufficiently resistant to etching, causing film floating in the etching process or side etching. This is because problems such as an increase in the amount of etching occur. Therefore, after the development step, a hardening solution is supplied to the metal thin plate, for example, the metal thin plate is immersed in the hardening solution to absorb chromium (IV) into the resist film, and then heated to a hexavalent value. Chromium is changed to trivalent chromium, and the etching resistance of the resist film is improved by a crosslinking reaction between chromium (III) and casein or PVA.

As a hardening solution, a solution containing chromic anhydride is generally used. However, if the concentration of chromic anhydride in the solution is not appropriate, unevenness in the processing of the resist film occurs, and a shadow mask is formed. Etc., the quality of the product will be degraded. Generally, the concentration of chromic anhydride in the hardening solution is determined by the methods described in JP-A-57-148859 and JP-A-57-20056.
7, JP-A-6-337524, JP-A-8-375
As disclosed in Japanese Patent Application Laid-Open No. 699751, Japanese Patent Application Laid-Open No. 8-138439, Japanese Patent Publication No. 3-262264, etc., the content is set to 1% to 15%.

[0005]

However, in recent years, the definition of shadow masks has been increased, and when a resist film having a high-definition pattern is hardened by using a hardening solution having the above-mentioned concentration range, the resist is hardened. Processing unevenness occurs on the membrane,
There is a problem that the diameter of a large number of minute holes formed in the resist film surface (the minute holes where a large number of minute through holes are to be formed by etching the exposed metal surface in the etching step) is caused. Was newly found.

SUMMARY OF THE INVENTION The present invention has been made to solve a problem newly appearing as the shadow mask and the like have been refined as described above, and it is an object of the present invention to provide a resist film having a high-definition pattern. Irrespective of whether or not the resist film hardens, an object of the present invention is to provide a method of hardening a resist film which does not cause processing unevenness in the resist film and does not cause a variation in the diameter of a large number of micro holes formed on the resist film surface. .

[0007]

According to the first aspect of the present invention, chromic anhydride is contained in a metal sheet having a main surface on which a resist film having a predetermined pattern containing casein and dichromate is formed. A method for hardening a resist film, comprising supplying a hardening solution and hardening the resist film, wherein the concentration of chromic anhydride in the hardening solution is in the range of 0.2% to 0.4%. It is characterized by being prepared as follows.

According to a second aspect of the present invention, a hardening solution containing chromic anhydride is supplied to a metal sheet having a main surface on which a resist film containing polyvinyl alcohol and dichromate and having a predetermined pattern is formed. In the method for hardening a resist film, the hardening treatment is performed on the resist film, wherein the concentration of chromic anhydride in the hardened film is adjusted within a range from 0.8% to less than 1.0%. Features.

According to the hardening method of the invention, the concentration of chromic anhydride in the hardening solution for hardening the resist film containing casein and dichromate is 0.2%.
Is adjusted within the range of from 0.4% to 0.4%, regardless of whether or not the resist film has a high-definition pattern, no processing unevenness occurs on the resist film, and the resist film surface Variations in the diameter of a large number of minute holes are eliminated or reduced. The resist film obtained by the hardening process has a sufficient etching resistance.

According to a second aspect of the present invention, the concentration of chromic anhydride in a hardening solution for hardening a resist film containing polyvinyl alcohol and dichromate is from 0.8% to 1.0%.
By being adjusted within the range of less than 0%, regardless of whether or not the resist film has a high-definition pattern, there is no processing unevenness in the resist film, and many resist films are formed on the resist film surface. The variation in the diameter of the small hole thus eliminated is reduced or reduced. The resist film obtained by the hardening process has a sufficient etching resistance.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

In the method for hardening a resist film according to the present invention, first, chromic anhydride is contained in a thin metal plate having a main surface formed with a resist film having a predetermined pattern formed through a developing step. Supply hardener. For example, a metal sheet is immersed in an aqueous solution of chromic anhydride stored in a dura bath, a chromic anhydride solution is sprayed from a spray nozzle onto the main surface of the metal sheet, or a shower nozzle is applied to the main surface of the metal sheet. An aqueous solution of chromic anhydride is dripped. Next, the metal sheet supplied with the chromic anhydride aqueous solution on the main surface is washed in a washing tank by, for example, spraying hot water onto the main surface of the metal sheet from a spray nozzle arranged in line along the conveying path of the metal sheet. After rinsing, the main surface of the metal sheet is drained by a squeezing roller, an air knife, or the like, and thereafter, the metal sheet is heated at an appropriate temperature for an appropriate time in a burning chamber for an appropriate time to complete the hardening process. The metal sheet after the hardening process is sent to an etching step.

In this hardening treatment method, the concentration of the aqueous solution of chromic anhydride used as a hardening solution is adjusted to an appropriate range depending on the type of the constituent material of the resist film formed on the main surface of the metal sheet. By doing so, it is possible to obtain a high-quality resist film that has sufficient etching resistance, and does not cause processing unevenness or a variation in the diameter of a large number of fine holes formed on the resist film surface. I do.
That is, for a resist film containing casein such as milk casein as a base material and dichromate as a sensitizer, the concentration of the aqueous solution of chromic anhydride is from 0.2% to 0.1%.
Prepare up to 4%. For a resist film containing polyvinyl alcohol as the base material and dichromate as the sensitizer, the concentration of the aqueous solution of chromic anhydride is adjusted within the range of 0.8% to less than 1.0%. These findings on the concentration range of the aqueous solution of chromic anhydride are obtained from experimental results and studies as described later.

[0014]

EXAMPLES Next, specific examples of the hardening method of the present invention will be described with reference to experimental examples.

[When a casein-containing resist is used] A metal thin plate having a thickness of 0.13 mm and a thickness of 500 m
A steel plate for shadow mask having a size of mx 5,900 mm was used, and a resist (photosensitive solution) containing milk casein and ammonium dichromate was applied to both main surfaces of the thin metal plate by a dipping-pulling method. Thereafter, the resist was dried at a temperature of 80 ° C. for 4 minutes to form a resist film having a thickness of 6 μm on both main surfaces of the thin metal plate. next,
On the surface of the resist film formed on one main surface of the metal thin plate, a negative pattern having a large number of circular images having a diameter of 80 μm was formed on the surface of the resist film formed on the other main surface.
A negative pattern having a large number of circular images having a diameter of 200 μm,
Match the position of the circular image on both main surfaces and bring them close together,
Each resist film was exposed from a position separated by 500 mm using a 5 kW mercury lamp. Subsequently, using ion-exchanged water at a temperature of 50 ° C., the resist films on both main surfaces of the thin metal plate are developed for 40 seconds at a spray pressure of 1 kg / cm ₂ , respectively, and are respectively applied to both main surfaces of the thin metal plate. A resist film having the following pattern was formed. Next, the metal sheet was immersed in an aqueous solution of chromic anhydride having different concentrations of chromic anhydride for 60 seconds, washed and drained, and thereafter, the resist film was subjected to a burning treatment at a temperature of 200 ° C. for 90 seconds. .

With respect to the resist film formed on the main surface of the thin metal plate by the above-described processing steps, evaluation of the variation in the diameter of the fine holes formed on the resist film surface, visual inspection by reflected light of an incandescent lamp, optical microscope Then, the degree of cutting of the circular image was observed by an electron microscope, and the amount of side etching by the etching treatment was observed.

<Evaluation of variation in diameter of micro-holes formed in resist film surface> The diameter of micro-holes formed in each resist film surface hardened using various concentrations of chromic anhydride aqueous solution was measured. Then, the adjacent variation of the hole diameter was examined.
The measurement of the hole diameter was performed for 10 rows × 10 columns = 100 adjacent micro holes, the standard deviation thereof was calculated, and the adjacent variation was represented by the standard deviation. Table 1 shows the results.

[0018]

[Table 1]

As can be seen from the results shown in Table 1, the adjacent variation shows the minimum value when the concentration of the chromic anhydride aqueous solution is around 0.3%, and the concentration of the chromic anhydride aqueous solution is 0.4%. Even when the value exceeded 0.2%, the value increased.

<Visual inspection by reflected light of incandescent lamp> The presence or absence of unevenness of each resist film surface hardened using chromic anhydride aqueous solution of various concentrations was visually inspected by reflected light of incandescent lamp. As a result, when the concentration of the aqueous solution of chromic anhydride was in the range of 0.2% to 0.4%, almost no unevenness was observed. In contrast, when the concentration of the aqueous solution of chromic anhydride exceeds 0.4%, and
When it was less than 0.2%, slight unevenness was observed.

<Observation of Circular Image Cut by Optical Microscope and Electron Microscope> Observation by a microscope shows that the circular image of the fine hole formed on the resist film surface is cut by the concentration of the aqueous solution of chromic anhydride. Was not found.

<Observation of Side Etch Amount by Etching> Metal sheet (sample) having resist film formed by hardening using chromic anhydride aqueous solution of various concentrations
Was attached to a production line and etched. As a result, when the concentration of the aqueous solution of chromic anhydride was 0.05% and 0.1%, the side etch amount tended to increase slightly, but at other concentrations,
The side etch amount was small.

[When a Resist Containing Polyvinyl Alcohol is Used] By the same processing steps as above, the type of resist is changed to a resist containing polyvinyl alcohol and ammonium dichromate, and the resist of the metal sheet is removed. A resist film was formed on the surface, and for each of the formed resist films, the evaluation of the variation in the diameter of the fine holes formed on the resist film surface and the visual inspection using reflected light of an incandescent lamp were performed.

The adjacent variation in the diameter of the fine holes formed in the resist film surface hardened with various concentrations of chromic anhydride aqueous solution was evaluated by the same method as described above. Table 2 shows the results.

[0025]

[Table 2]

As can be seen from the results shown in Table 2, the adjacent variation was caused when the concentration of the aqueous solution of chromic anhydride was 0.8% to 0.8%.
The minimum was at 1.2%. Further, within the concentration range, the result of the visual inspection for unevenness was good.

[0027]

According to the method for processing a hardened resist film according to the first and second aspects of the present invention, processing unevenness is caused in the resist film regardless of whether the resist film has a high-definition pattern. This eliminates the occurrence of pits and variations in the diameter of the microholes formed on the resist film surface, resulting in a high-quality resist film, which can be used to improve the quality of shadow masks, aperture grills, lead frames, and other products. Will contribute. Further, since the concentration of chromic anhydride in the hardening solution is low, the amount of chromic anhydride used is reduced, and the load on the environment is reduced, and the amount of cleaning water used is also reduced.

Claims (2)

[Claims] 1. A hardening solution containing chromic anhydride is supplied to a metal sheet having a main surface on which a resist film containing casein and dichromate and having a predetermined pattern is formed, and the resist film is formed. A method for hardening a resist film to be hardened, wherein the concentration of chromic anhydride in the hardening solution is 0.2% to 0.1%.
A method of hardening a resist film, wherein the method is prepared within a range of up to 4%. 2. A hardening solution containing chromic anhydride is supplied to a metal sheet having a resist film containing polyvinyl alcohol and dichromate and having a predetermined pattern formed on a main surface thereof. A method of hardening a resist film, wherein the concentration of chromic anhydride in the hardened film is from 0.8% to 1.0%.
%. A method for hardening a resist film, which is prepared within a range of less than 0.1%.