JPH11248922A - Manufacture of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture of a color filter having superior flatness. SOLUTION: When the color filter manufactured by repeating a process, wherein a specific image is formed by forming a specific pixel section film on a translucent substrate, forming a photosensitive colored layer, arranging a mask having a specific opening on the reverse surface of the surface of the translucent substrate having the pixel section film formed, and irradiating the photosensitive colored layer with an active light beam from the reverse surface of the translucent substrate through the mask opening part, as many times as specified, the transparent substrate is 0.3 to 0.8 mm thick and the mask opening part is 60 μm to the width of the pixel wide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color filter used in a color liquid crystal display device or the like.

[0002]

2. Description of the Related Art Liquid crystal displays (hereinafter abbreviated as LCDs)
Utilizing features such as thinness, small size, and low power consumption, is currently used for display units such as watches, calculators, TVs, and personal computers. In recent years, color LCDs have been developed and OA / AV
It has begun to be used in many applications such as navigation systems and viewfinders, mainly in equipment, and the market is expected to expand rapidly in the future.

As shown in FIG. 5, a color filter for displaying a color image on an LCD is a light-shielding layer 1 having a lattice pattern.
R (red), G on the substrate 2 such as a glass plate on which
(Green) and B (blue) color pixel 3 (300 × 10
0 × 2 μm), and a transparent overcoat layer (OC) 4 is formed thereon. 5 is a polarizing plate,
Reference numeral 6 denotes an ITO electrode.

[0004] In the color LCD, the color filter 7 has an LC
D, the display screen can be colored by transmitting backlight light through a color filter. 8 is an alignment film, 9 is a liquid crystal, 10 is a sealing material, 11 is a top coat layer, 12 is an ITO electrode, 13 is a substrate such as a glass plate, 14
Is a polarizing plate.

At present, color filters are mainly manufactured using a dyeing method. However, in this method, a step of forming a pixel by applying a transparent photosensitive resin on a glass substrate, drying, exposing, and developing, dyeing with a dye, and then forming a color mixing prevention layer is required to be repeated three times. Therefore, reliability (lightfastness,
Heat resistance). Therefore, some color filters using a pigment as a coloring agent have been proposed, among which are an electrodeposition method, a printing method, and a photolithography method (photolithography method).

However, the electrodeposition method requires the formation of an electrode pattern. (1) The degree of freedom of the pattern is small.
(2) The cost is high, and the printing method has problems such as (1) it is difficult to align a large substrate and the resolution is low, so it is difficult to cope with miniaturization, and (2) the flatness of the pattern is poor. The photolithography method is considered to be the mainstream. The photolithography method includes a liquid resist method and a film transfer method. In the liquid resist method, a varnish in which a pigment is dispersed in a photosensitive resin is applied on a glass substrate by a spinner, dried, exposed, and developed to form color pixels. On the other hand, in the film transfer method, a varnish is formed into a film in the same manner as a photosensitive film for a printed board. After lamination on a substrate, color pixels are formed by exposure and development.

[0007]

Heretofore, metal chromium having a high optical density per unit film thickness has been applied to the light shielding layer. In the case of a thin film transistor (TFT) liquid crystal, the optical density of the light shielding layer is required to be 3 or more in order to prevent malfunction of the TFT. To achieve this optical density, a thickness of 0.15 μm was sufficient for chromium metal. However, since the metal chromium reflectance is high, there is a problem that reflection of external light is high when the LCD is used, and visibility is reduced. Therefore,
In order to reduce the reflectance, a method of laminating chromium oxide is adopted, and the visibility is improved. However, there is a problem that the cost is high because metal chromium and chromium oxide are formed by a vacuum deposition method such as sputtering. In order to solve this problem, a resin in which a black coloring layer material such as carbon is dispersed in a photocurable resin, and a resin light-shielding layer in which graphite is dispersed in a thermosetting resin are being adopted. However, the optical density per unit film thickness of the resin light-shielding layer is not as high as that of metallic chromium, and a thickness of 0.5 to 1.5 μm is required to obtain an optical density of 3. For this reason, in the conventional method of exposing from the pixel surface side, the projection of the thickness of the resin light-shielding layer is generally formed due to the overlapping of the light-shielding layer and the pixel, so that the flatness of the entire color filter is significantly impaired. Therefore, if the projections formed by the overlap of the light-shielding layer and the pixel can be effectively removed or reduced, a color filter that does not require a flattening protective film and has excellent color material flatness can be manufactured. An effective method for producing a color filter that does not have convex portions is described in Japanese Patent No. 25.
No. 87653 discloses a backside exposure method in which a colored layer is exposed from the substrate side. However, in the back exposure method, since the colored layer is exposed through a translucent substrate, the distance from the photomask to the colored layer becomes longer. As a result, the influence of the diffracted light at the edge of the photomask increases, and the adjacent pixel portion is exposed.

Another problem is how to support the substrate during exposure. If the exposure machine stage is used as a support, the colored layer is processed without any protection, so that when it comes into contact with the exposure machine stage or the transport system, there is a problem that dust is generated due to dust and scratches on the pixels. Was. Further, if the substrate is supported only at the ends, the substrate will bend, and it is difficult to form pixels with high positioning accuracy.

The present invention has been made in view of such a problem, and has commercialized a back exposure method which is a method of manufacturing a color filter having excellent flatness, which is not affected by the thickness of a light-shielding layer serving as a base. Another object of the present invention is to provide a method of manufacturing a color filter that prevents scratches generated when the wafer comes into contact with an exposure machine stage or a transport system and prevents white defects due to foreign matter on the back surface of a substrate.

[0010]

According to a method of manufacturing a color filter of the present invention, a predetermined pixel partition film is formed on a light-transmitting substrate, a photosensitive coloring layer is formed, and a pixel partition film of the light-transmitting substrate is formed. A step of arranging a mask having a predetermined opening on the back surface of the surface on which is formed, irradiating the photosensitive coloring layer with actinic light from the back surface of the light-transmitting substrate through the mask opening, and forming a predetermined image by development Is performed a predetermined number of times, wherein the thickness of the translucent substrate is 0.3 to 0.8 mm, and the width of the mask opening is 60 μm to the width of the pixel. It is assumed that.

The first problem in exposing a pixel from the back side is that, as described above, since the colored layer is exposed through the translucent substrate, the distance from the photomask to the colored layer (= substrate thickness and exposure gap) Becomes longer, and as a result, the influence of the diffracted light at the edge of the photomask increases, and the adjacent pixel portion is exposed (FIG. 2). As means for avoiding exposure of adjacent pixel portions in the backside exposure process, there are two means of making the width of the mask opening smaller than the width of the corresponding pixel and reducing the thickness of the substrate. As a result of our intensive study of the mask opening width, when a high-pressure mercury lamp was used as the exposure light source, the mask opening width was 6 mm.
0 μm was found to be the limit. This is because when the mask opening width is 60 μm or less, the exposure intensity distribution becomes convex as shown in FIG. 3, and the formed pixels become convex.
With a mask opening width of 60 μm or more, a normal exposure intensity distribution was obtained as shown in FIG. 4, and flat pixels could be formed.
10.4 inch VGA on 1.1mm thick glass substrate
An attempt was made to produce a color filter (480 × 640 dots, pixel width 76 μm). As a result, even if the mask opening width was 60 μm, the adjacent pixel portion was exposed. As a result of intensive studies on the thickness of the substrate, it has been found that if the substrate thickness is 0.8 μm or less, even if the mask opening width is 60 μm or more, pixels can be formed so that adjacent pixel portions are not exposed. The thinner the substrate, the wider the mask opening width, and the better the pixel flatness. However, if the thickness of the substrate is 0.3 mm or less, the substrate is likely to bend and the displacement of the substrate due to the deflection of the substrate during exposure is large. Therefore, the thickness of the substrate is preferably 0.3 mm or more. According to this method, a high-definition color filter can be manufactured. For example, 12.1 inch SVGA is 600 × 800 dots,
Since the pixel width is 80 μm, if a substrate having a thickness of 0.8 mm or less is used, pixels can be formed with a mask opening width of 60 μm so that adjacent pixel portions are not exposed. As described above, a color filter having a pixel width of 70 μm or more can be manufactured by the same method.

In the present invention, a photosensitive colored film formed on a support film is attached to a light-transmitting substrate on which a predetermined pixel partitioning film is formed, thereby forming a photosensitive colored layer. The actinic ray can be irradiated in a state where the support film is adhered to the photosensitive colored film. The effect of irradiating the photosensitive colored film with actinic rays in a state where the support film is adhered to the photosensitive colored film can reduce the exposure amount required for pixel formation. This is because the photosensitive colored layer is not directly exposed to the air, so that radicals generated in the colored layer by irradiation with actinic rays can be effectively photocured without being attacked by oxygen in the air. . Furthermore, since the exposure amount can be reduced, the mask opening width can be made wider than usual, and the flatness of the formed pixels can be improved. In addition, since exposure can be performed while the base film is attached, it is possible to prevent scratches generated when the exposure device comes into contact with an exposure machine stage or a transport system, and to prevent white defects due to foreign matter on the back surface of the substrate.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a light shielding layer, 2 is a glass substrate,
3 is a colored layer, 15 is a base film, 16 is an exposure stage, 17 is a photomask, and 18 is a light shielding film of the photomask. Corning # 1737 glass substrate 2 having a length of 200 mm, a width of 300 mm and a thickness of 0.7 mm was used as a transparent substrate. First, a pixel partition film was formed on a substrate. As the pixel partition film 1, GA-66M (trade name) manufactured by Hitachi Powder Co., Ltd., which is formed by dispersing graphite in a thermosetting resin and forming a pattern by a lift-off method, was used. Positive photoresist Az-1350 (trade name) manufactured by Shipley as a photoresist for lift-off on glass substrate 2
Is applied by spin coating at a rotation speed of 1000 rpm for about 20 seconds to a thickness of about 1.2 μm. Next, prebaking is performed on a hot plate at 90 ° C. for 5 minutes. Next, a light intensity of 405 nm and a light intensity of 120 mj using a super high pressure mercury lamp through a photomask.
/ Cm ² exposure. Next, after developing with a 1% aqueous solution of potassium hydroxide at room temperature for 1 minute and 30 seconds, washing and draining,
Post-bake at 100 ° C. Next, the graphite dispersion GA-66M (trade name) is applied by spin coating at a rotation speed of 500 rpm for 10 seconds to a thickness of about 1 μm. Next, drying is performed in a clean oven at 90 ° C. for 15 minutes. Next, the photoresist is dissolved in a 2% aqueous solution of potassium hydroxide for 1 minute, washed with water at a water pressure of 3 kg / cm ² , drained, and cured in a clean oven at 200 ° C. for 30 minutes. At this time, the pixel partition film pattern has a width of 20 μm, a pitch of 100 μm in width, 300 μm in height, and a pixel width of 80 μm.
The numerical aperture was set to 640 horizontal rows (3 colors) and 480 vertical rows. Thus, a glass substrate with a pixel partition film is completed. In the present invention, graphite by the lift-off method is used, but any material can be used as long as it can block active light having a photosensitive wavelength for exposing a pixel. The one produced by a photo method in which carbon is dispersed in a photocurable resin, or the one produced by etching with a photoresist in which carbon is dispersed in a thermosetting resin may be used. Further, a material in which a metal oxide is dispersed instead of the carbon may be used. Also,
A conventional metal or a laminated film of a metal and a metal oxide, a laminated film of a metal and a metal nitride, or a laminated film of a metal, a metal oxide, and a metal nitride may be used.

Next, a colored layer forming step is started. The film has a cushion layer containing a light absorbing agent on a 50 μm thick polyethylene terephthalate (PET) film with a thickness of 20 μm.
A two-layer film for CF manufactured by Hitachi Chemical Co., Ltd., disclosed in JP-A-8-212222, in which a coloring layer having an oxygen-inhibiting function was applied by a roll-to-roll coating of 1.6 μm. First, as a first color, a red film was laminated at a temperature of 80 ° C., a lamination speed of 0.2 m / min, and a roll pressure of 5 kg / cm ^2.
Is bonded to the glass substrate on which the pixel partition film has been formed. Although the colored layer having the oxygen inhibiting function is used here, a material having no oxygen inhibiting function may be used. Next, an exposure step is started. The exposure is performed by using a proximity exposure machine so that the colored layer side is supported by an exposure stage so that the glass side of the substrate and the pixel partition film side of the photomask face each other.
Next, the position of the photomask and the substrate is adjusted to 405 nm.
At 200 mj / cm ² . The gap between the substrate and the photomask was 60 μm. This gap amount is 0 to 50
Any value is acceptable as long as it is in the range of 0, but it is better to be as small as possible. Next, peel the base film together with the cushion layer,
Develop with an alkali developer, wash with water, drain and cure. This process is repeated for green and blue. The order of formation is not limited. At this time, the opening width of the photomask is 60 to
The adjacent pixel portion was not exposed at any opening width of 80 μm. After the three colors are formed, washing is performed, and an overcoat is formed thereon as necessary, thereby completing a color filter.

[0015]

According to the present invention, the back exposure method, which is a method for producing a color filter excellent in flatness, which is not affected by the thickness of the underlying light-shielding layer, is put into practical use, and comes into contact with an exposure machine stage and a transport system. This makes it possible to produce a color filter having no white defects due to scratches generated at the time and foreign substances on the back surface of the substrate.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing one embodiment of a method for manufacturing a color filter of the present invention.

FIG. 2 is a cross-sectional view for explaining exposure of an adjacent pixel portion.

FIG. 3 is a sectional view for explaining an exposure intensity distribution when a mask width is 60 μm or less.

FIG. 4 is a sectional view for explaining an exposure intensity distribution when a mask width is 60 μm or more.

FIG. 5 is a cross-sectional view of a color liquid crystal display for explaining a color filter.

[Explanation of symbols]

 Reference Signs List 1 light shielding layer 2 glass substrate 3 pixel 3a-1 pixel 3a-2 pixel 3a-3 pixel 3b-1 pixel 3b-2 pixel 3b-3 pixel 4 overcoat layer 5 polarizing plate 6 ITO electrode 7 color filter 8 alignment film 9 liquid crystal DESCRIPTION OF SYMBOLS 10 Seal material 11 Top coat layer 12 ITO electrode 13 Glass plate 14 Polarizer 15 Base film 16 Exposure stage 17 Photomask 18 Light shielding film 19 Cushion layer 20 Color material film 21 Scratches 22 Dust 23 Projections

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Ken Yoshida 48 Wadai, Tsukuba, Ibaraki Prefecture Within Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd.

Claims (2)

[Claims] 1. A light-transmitting substrate is provided with a predetermined pixel partition film, a photosensitive coloring layer is formed, and a predetermined opening is provided on the back surface of the light-transmitting substrate on which the pixel partition film is formed. A method of manufacturing a color filter, comprising arranging a mask, irradiating the photosensitive coloring layer with actinic rays from the back surface of the light-transmitting substrate through the mask opening, and performing a predetermined number of steps of forming a predetermined image by development, A method for manufacturing a color filter, wherein the thickness of the light-transmitting substrate is 0.3 to 0.8 mm, and the width of the mask opening is 60 μm to the width of a pixel. 2. A photosensitive colored film formed on a support film is attached to a light-transmitting substrate on which a predetermined pixel partitioning film is formed to form a photosensitive colored layer, and actinic light is applied to the photosensitive colored film. 2. The method according to claim 1, wherein the irradiation is carried out in a state in which the support film is adhered to the photosensitive colored film.