JP2002278078A - Exposure device for shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device for a photomask which effectively suppresses deterioration in exposure quality by a simple means although the light source lamp used for the exposure device has lower exposure quality since light including infrared lights in addition to ultraviolet light needed for exposure is emitted to cause thermal fog, namely, a phenomenon of exposure to heat ray and no effective countermeasure against the thermal fog is taken. SOLUTION: A reflector 14 selects and reflects only the light beam of a wavelength region including the ultraviolet light beam in the light beam emitted by the light source lamp 16 and the selected light beams are supplied to photomask 12 and 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus used for printing a pattern when a shadow mask is manufactured by a photo-etching method.

[0002]

2. Description of the Related Art In general, a color cathode ray tube used for a color television receiver or a color display has a substantially rectangular face panel opposed to a phosphor screen provided on the inner surface of a substantially rectangular face panel. A shadow mask is placed. A large number of openings are formed in a predetermined arrangement on an effective surface of the shadow mask facing the phosphor screen, and three electron beams emitted from the electron gun through each of the openings are selected to form a phosphor screen. Make up 3
It is formed in a structure to be incident on the color phosphor layer.

There are roughly two types of aperture shapes of the shadow mask, a circular shape and a rectangular shape. For a color cathode ray tube for a display for displaying characters and figures, a shadow mask having a circular shape is mainly used. For a consumer color cathode ray tube such as a color television receiver, a shadow mask having a rectangular hole is mainly used. In any of these shadow masks, the cross-sectional shape of the opening consists of a communication hole in which a large hole formed on the surface facing the phosphor screen and a small hole formed on the surface facing the electron gun communicate with each other. The diameter at the communicating portion between the large hole and the small hole is the effective diameter that substantially determines the opening diameter.

A shadow mask having such openings can be manufactured by a photoetching method.

That is, after a thin metal plate made of low carbon steel or an Fe—Ni alloy invar material having a thickness of about 0.1 to 0.3 mm is degreased and washed, a photosensitive agent is applied to both surfaces thereof to form a film. Forms a resist of about 7 to 8 μm. Next, a pair of photomasks in which a pattern corresponding to the opening of the large hole and the small hole of the shadow mask are formed on the resist on both surfaces thereof are vacuum-adhered to each other, and the resist formed on both surfaces of the thin metal plate through this photomask. Are simultaneously exposed using ultraviolet rays, so that the pattern of the shadow mask is printed on the resist. Next, the resist baked with this pattern is developed with hot water to remove unexposed portions, and the openings of the shadow mask where portions of the sheet metal where the openings are to be formed on both sides of the sheet metal are exposed are exposed. A corresponding resist pattern is formed. After the resist is burned at about 200 ° C. to improve the corrosion resistance of the subsequent etching, a ferric chloride solution heated to 60 ° C. or more is applied to both sides of the thin metal plate on which the resist is formed. By spraying an etching solution consisting of: a large hole from one surface of the metal sheet and a small hole from the other surface, thereby forming a communication hole in which the large hole and the small hole communicate with each other. . Then, after that, the resist remaining on both surfaces of the thin metal plate is peeled off to produce a shadow mask.

Referring to FIG. 3, a description will be given of an exposure apparatus generally used in an exposure step for printing a photomask pattern performed during the shadow mask manufacturing step.

That is, a photomask 52 in which a pattern corresponding to a large hole is formed on one side of a thin metal plate 51 coated with a photoresist on both sides, and a pattern corresponding to a small hole is formed on the other side. The photomasks 53 are arranged facing each other. A light source device 56 formed of a light source lamp 54 and a reflection plate 55 is disposed on each of the photomasks 52 and 53 on the side opposite to the thin metal plate 51 to constitute an exposure apparatus for a shadow mask. .

A light source lamp 54 constituting the exposure apparatus
For example, a high-pressure mercury lamp or a metal halide lamp that emits ultraviolet light required for exposure is used. As the reflection plate 55, an embossed aluminum plate that is easily processed is used. Adjusts the light distribution on the exposure surface by finely adjusting the unevenness of the reflection surface.

The emission wavelength characteristics of the high-pressure mercury lamp used for the light source lamp 54 include a wavelength of 10 to 380 nm, a wavelength required for exposure of the resist, and a wavelength of 60 to 60 nm.
It includes a wide range of wavelengths up to 0 nm or more.

On the other hand, as a resist used in the production of the shadow mask, a photosensitive agent mainly containing casein and dichromate is generally widely used, but this resist material is water-soluble and inexpensive. Although it has many advantages such as high film strength, it also has a problem that a photosensitive phenomenon due to heat other than ultraviolet rays, that is, a so-called "heat fogging" is likely to occur.

[0011] In the high-pressure mercury lamp used in this exposure apparatus, as described above, the casein-based resist also generates infrared rays having a wavelength of 780 to 1000 nm, which easily causes heat covering, and in addition, it is worse. Is a reflection plate 55
Since the aluminum plate used for the device has the property of totally reflecting not only ultraviolet rays but also infrared rays, it has a bad surface for an exposure apparatus that transmits even infrared rays that cause heat to the exposed surface. I have.

Further, the light source lamp 54 for exposure and the photomasks 52 and 53 are arranged close to each other from the viewpoint of securing sufficient ultraviolet intensity in the exposure apparatus and the layout of the exposure apparatus. Since the distance between the two is very short, and the heat itself generated by the light source lamp 54 is easily transmitted, the heat generated by the light source lamp 54 is also one of the factors that cause the resist to be covered with heat. I was

In the exposure apparatus having such a configuration, a 7KW metal halide lamp is used as the light source lamp 54, the distance from the lamp 54 to the photomasks 52 and 53 is set to about 1100 mm, and irradiation is continued for 100 seconds. The photomasks 52 and 53 are irradiated with the time, and the surface temperatures of the photomasks 52 and 53 at this time are measured using a surface thermometer. As a result, the surface temperatures of the photomasks 52 and 53 rise to about 35 to 37 ° C. Turned out to be. At this surface temperature, there is a possibility that exposure due to heat is performed.

Japanese Patent Application Laid-Open No. H11-249315 discloses a similar configuration for such a conventional exposure apparatus. However, this publication further discloses that a large number of holes are required for exposure. Since light intensity is required and high resolution is required on the small hole side, light irradiating means are arranged opposite to both surfaces of the thin metal plate on which the resist is formed, respectively, to meet the requirements for large holes and small holes As described above, an exposure apparatus having different pattern resolutions is also disclosed.

It is presumed that the intended purpose for printing the pattern for large holes and small holes is achieved by these means. Further, in this publication, an example in which a reflecting mirror is installed in the optical path between the light source lamp and the photomask is also found, and when this reflecting mirror is used, the description between the light source lamp and the photomask is made. To increase the distance of
Although it is difficult to transmit heat from the light source lamp, no countermeasure has been taken against the above-mentioned heat fogging.

[0016]

In recent color cathode ray tubes, higher definition and higher quality than ever have been demanded. Along with this, such heat cover,
Since the quality of the shadow mask is degraded, and eventually the quality of the color cathode ray tube is degraded, it has emerged as a fatal problem.

As a method of solving such a heat fogging problem, for example, JP-A-2000-231199 discloses a method.
There is disclosed an exposure apparatus in which a heat ray blocking filter that reflects or absorbs infrared rays while passing ultraviolet rays is disposed around the outer periphery of a light source lamp. According to the disclosed contents, glass tubes of mercury lamps and metal halide lamps,
An interference filter is formed by a metal oxide film such as TiO ₂ , SiO ₂ , or AlO _{3 by} vacuum evaporation, and this filter has a function as a bandpass filter that transmits ultraviolet rays but reflects infrared rays. .

Therefore, although it is presumed that it is possible to reduce the irradiation of infrared rays as compared with the conventional exposure apparatus, it is difficult to generate infrared rays because of the arrangement of the heat ray cutoff filter around the light source lamp. Since it is located close to the lamp that is the source, the amount of infrared rays generated is also extremely large, which makes it difficult to block sufficiently with the heat ray cutoff filter alone. It is considered that the amount of infrared rays leaking without being increased also increases, and a sufficient blocking effect cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide an exposure apparatus for a shadow mask which is designed to minimize transmission of infrared rays which cause a heat fogging phenomenon to a photomask side. And

[0020]

According to the present invention, a pair of photomasks are arranged on both sides of a thin metal plate coated with a photoresist on both sides, and the photoresist is exposed by irradiating an exposure light beam from a light source device. In an exposure apparatus for a shadow mask, a reflecting mirror having a function of limiting a reflectance by a wavelength is interposed on an optical path between a light source device and a photomask,
The light reflected from the reflecting mirror was applied to the photomask.

By forming a multilayer film made of a metal oxide on the reflecting mirror as described above, a function of limiting the reflectivity according to the wavelength is added, and by increasing the optical path length from the light source device, the exposure process can be performed. Exposure can be performed without causing thermal cover on the resist, so that stable and high-quality exposure can be performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an exposure apparatus for a shadow mask according to the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the exposure apparatus according to the present invention comprises, on one side of a metal thin plate 11 having a photoresist coated on both sides, a photomask 12 having a pattern corresponding to a large hole formed thereon. Photomasks 13 having patterns corresponding to the small holes formed on the other surface side are arranged facing each other. On the opposite side of the photomasks 12 and 13 from the thin metal plate 11, reflecting mirrors 14 inclined at a predetermined angle are arranged, respectively. Fly-eye lenses 15 each having a miniaturized lens itself for keeping the illuminance of incident light constant are arranged. On the extension of the fly-eye lens 15, a high-pressure mercury lamp or a metal halide that emits ultraviolet light required for exposure is provided. A light source device 18 formed by a light source lamp 16 such as a lamp and a reflecting plate 17 made of an embossed aluminum plate is arranged to constitute a shadow mask exposure device.

The reflecting mirror 14 used here is formed in a flat shape, and the reflecting surface of the quartz glass substrate 19 is
A _two- layer structure in which a first-layer metal oxide 20 made of TiO ₂ is formed, and a second-layer metal oxide 21 made of TiO _{2 is} further applied on the first-layer metal oxide 20 A multilayer film 22 having a structure is provided. The multilayer film 22 is provided to limit the reflectance depending on the wavelength. Of the light projected from the light source lamp 16, about 500 n
It has a function of reflecting light in a wavelength range including an ultraviolet region of m or less, and restricting light of a wavelength longer than that from being reflected.

The light source lamp 16 and the photomask 1
By installing the reflecting mirror 14 in the optical path between the photomasks 2 and 13, the optical path length is increased so that stable and uniform light is supplied to the photomasks 12 and 13. By taking advantage of the fact that it is inversely reduced, by arranging it as far as possible from the reflection plate 17 made of an aluminum plate, the effect of blocking heat rays can be increased. Further, it is possible to reduce the size of the device while ensuring a sufficient optical path length.

The exposure apparatus having such a configuration was assembled as follows, and the surface temperatures of the photomasks 12 and 13 were measured by a measurement method similar to the conventional measurement.

That is, a metal halide lamp is used as the light source lamp 16, and the output of the light source lamp 16 is 12K.
W, and the optical path length from the light source lamp 16 to the photomasks 12 and 13 is set to be 2000 mm, which is about twice as large as the optical path length of the conventional apparatus, so that the same conditions as those of the conventional apparatus are obtained. The fly-eye lens 15 was omitted to constitute the device. The same irradiation time as that of the conventional measurement condition was continuously performed for 100 seconds, and the surface temperatures of the photomasks 12 and 13 were measured with a surface thermometer.
13 has a surface temperature of 25 ° C., which is about 1
It was demonstrated that the temperature rise was suppressed by about 0 ° C. This 10
The effect of reducing the temperature of ° C. is a temperature range in which heat fogging can be sufficiently suppressed, and therefore, by using the exposure apparatus of the present invention, a heat fogging phenomenon in which exposure by heat is performed can be suppressed, A high quality shadow mask can be manufactured, and a high quality color cathode ray tube can be obtained.

Further, the present invention can be configured as shown in FIG. 2 without being limited to the embodiment shown in FIG.

That is, in the exposure apparatus shown in FIG. 1, a case where a plane mirror is used as the reflecting mirror 14 has been described, but this is formed into a curved surface shape corresponding to the incident angle of the light projected from the light source device 18. It is configured as a curved reflecting mirror 14 having an inner surface formed therein, and the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

By using the reflecting mirror 14 having a curved surface as described above, it becomes possible to supply the exposure light rays, which are reflected by the reflecting mirror 14 and strike the photomasks 12 and 13, as substantially parallel light rays. Exposure light rays having a more uniform incident angle over the entire surface of the photomasks 12 and 13 can be formed, and a higher quality shadow mask can be formed. Also, as in the case of the apparatus of FIG. 1, if the fly-eye lens 15 is arranged in the optical path, it is possible to exhibit the effect of making the illuminance constant along with the incident angle with respect to the photomasks 12 and 13.

It is needless to say that the present invention is not limited to the configurations of the above-described embodiments, but various other applications and modifications such as changing the shape of the reflector are possible.

[0032]

As described above, according to the exposure apparatus of the present invention, a light beam having a wavelength range near infrared light contained in a light beam of a light source lamp is suppressed by a multilayer film made of a metal oxide. By providing a reflecting mirror that selects and reflects only light rays in the wavelength range including ultraviolet light required for exposure, it is possible to perform exposure without causing thermal cover on the photomask in the exposure process of shadow mask production. Thus, stable and high-quality exposure can be performed, and the quality of the manufactured shadow mask can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an exposure apparatus for a shadow mask according to the present invention.

FIG. 2 is a schematic configuration diagram showing another configuration example of the exposure apparatus for a shadow mask according to the present invention.

FIG. 3 is a schematic configuration diagram showing a conventional exposure apparatus for a shadow mask.

[Explanation of symbols]

 11: Metal thin plate 12, 13: Photomask 14: Reflector 16: Light source lamp 17: Reflector 18: Light source device 20, 21: Metal oxide 22: Multilayer film

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H042 DA08 DA12 DB02 DE00 2H048 FA05 FA09 FA18 FA24 GA04 GA17 GA33 2H097 AA01 BA10 EA01 GA45 LA20 5C027 HH09

Claims (3)

[Claims] 1. A shadow mask exposure apparatus for arranging a pair of photomasks on both side surfaces of a metal thin plate coated with a photoresist on both sides and irradiating an exposure light beam from a light source device to expose the photoresist. An exposure apparatus for a shadow mask, wherein a reflecting mirror having a function of limiting the reflectance by wavelength is interposed on an optical path between a light source device and a photomask, and light reflected from the reflecting mirror is irradiated on the photomask. . 2. An exposure apparatus for a shadow mask according to claim 1, wherein said reflection mirror includes a multilayer film made of a metal oxide on a reflection surface. 3. An exposure apparatus for a shadow mask according to claim 1, wherein said light source device comprises a light source lamp and a reflector made of an aluminum plate.