JPH11248920A - Production of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color filter with excellent flatness by forming a pixel partition film in such a manner that the cross-sectional area of the film increases with the distance from the light-transmitting substrate surface. SOLUTION: A glass substrate 2 is used as a transparent substrate. A positive photoresist for lift-off method is applied on the substrate 2 and prebaked. The resist is exposed through a photomask 17, developed, washed, dewatered and post-baked. Since the photoresist has low heat resistance, the resist deforms to form a forward tapered space in the cross section in the post-baking process. A graphite dispersion liquid as a light-shielding layer material prepared by dispersing a graphite in a thermosetting resin is applied thereon and dried. After the photoresist is dissolved, the layer is hardened. The pixel partition film 1 thus formed has a reversed shape of the base positive photoresist to have a reversed tapered shape. Namely, the cross-sectional area of the pixel partition film 1 increases with the distance from the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a color filter used in a color liquid crystal display device.

[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 (2) poor pattern flatness. At present, the photolithography method is considered to be the mainstream. For photolithography, liquid resists and films are contemplated. The liquid resist is formed by applying a varnish obtained by dispersing a pigment in a photosensitive resin on a glass substrate by a spinner, drying, exposing, and developing to form color pixels. On the other hand, the film is a film obtained by forming a varnish into a film in the same manner as the photosensitive film for a printed board, and after laminating on a substrate, exposing the base film as a support when the film has oxygen inhibition properties, and then exposing and developing. If the film has no oxygen-inhibiting properties, color pixels are formed by exposing and developing with the base film attached. Here, the light is irradiated from the colored layer side through a photomask.

[0007]

Heretofore, a light-shielding layer having a high light-shielding property has been required for a pixel division film, and metal chromium having a high optical density per unit film thickness has been applied. In a thin film transistor (TFT) liquid crystal, the optical density of the light shielding layer is TF
To prevent the malfunction of T, 3 or more is required. To achieve this optical density, the thickness of chromium metal is 0.15 μm.
It was enough. 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.

The resin light-shielding layer needs to be thicker than the metal light-shielding layer in order to obtain a necessary absorbance. By increasing the thickness of the resin light-shielding layer serving as a base, the pixel projections 1 shown in FIG.
6 occurred, and the flatness was impaired.
In order to improve the flatness, a back exposure method in which a pixel disclosed in Japanese Patent No. 2587653 or JP-A-7-120608 is exposed from the back side through a photomask and a light-shielding layer is used as a part of the photomask. Has been proposed.
However, the resin light-shielding layer has a so-called forward taper shape in which the area decreases as the distance from the light-transmitting substrate increases, and a concave portion 21 occurs at the boundary between the pixel and the resin light-shielding layer as shown in FIG. There was a problem of being damaged. Conventionally, after forming pixels to improve the flatness of a color filter, an overcoat (OC) was formed as a flattening layer. However, there is a problem that the cost is increased by further providing the OC. If the color filter has a concave portion, an ITO electrode (indium oxide-tin oxide) which is a transparent electrode is directly provided on the color filter, and when a predetermined line is formed by a photolithography method, there is a problem that the electrode is disconnected at the concave portion. Was. The present invention provides a method for manufacturing a color filter having excellent flatness.

[0009]

According to the manufacturing method of the present invention, a predetermined pixel partition film 1 is formed on a light transmitting substrate 2, a photosensitive colored layer 3a is formed, and a pixel partition film of the light transmitting substrate 2 is formed. A mask 17 having a predetermined opening is arranged on the back surface of the surface on which the light-transmitting substrate 1 is formed. The photosensitive coloring layer is irradiated with actinic rays 23 from the back surface of the light-transmitting substrate 2 through the mask opening. 3b is a method for manufacturing a color filter in which the step of forming 3b is performed a predetermined number of times, wherein the pixel partition film 1 is a film whose cross-sectional area increases as the distance from the transparent substrate surface increases. It is characterized by. By forming the pixel partition film 1 into a film having a cross-sectional area that increases as the distance from the light-transmitting substrate surface increases, a so-called reverse tapered shape, and by forming pixels by a backside exposure method, No pixels remain on the film,
Further, the present invention provides a color filter having no concave shape at the boundary between the pixel partition film and the pixel.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, reference numeral 2 in FIG. 1 denotes a glass substrate, 1 denotes a pixel partition film, 3a denotes a coloring layer, 17 denotes a photomask, and 18 denotes a light shielding film of the photomask. Here, as the distance of the pixel partition film 1 from the glass substrate 2 increases, the cross-sectional area increases. The coloring layer 3 is a photomask 1
7 is arranged on the back surface of the glass, the pixel partition film 1 and the photomask 17 are aligned so as to be in a predetermined position, and the back surface of the glass substrate 2 is irradiated with active light rays 23 and developed to form the pixels 3b. I do. The inverse tapered pixel partition film is
It can be easily obtained by forming the pixel partition film by a lift-off method. In the lift-off method, a required pixel partition film and an inverted pattern are formed in advance using a photoresist. A base material for forming a pixel partition film is applied thereto, and the photoresist is removed to obtain a pixel partition film. At this time, the cross-sectional shape of the photoresist becomes forward-tapered after the development or post-baking heat treatment. The photoresist and the pixel division film from which the inversion pattern is obtained necessarily have an inverse taper.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiment shown in FIG. Corning # 1727 glass vertical 2 as transparent substrate
A glass substrate 2 having a size of 00 mm × 300 mm in width × 1.1 mm in thickness was used. As the light-shielding layer material 1, GA-66M (trade name) manufactured by Hitachi Powder Co., Ltd., in which graphite was dispersed in a thermosetting resin and which was patterned by a lift-off method, was used. A positive photoresist Az-1350 manufactured by Shipley Co., Ltd. as a photoresist for lift-off is applied to a glass substrate 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 /
Expose to cm ² . Next, the film is developed with a 1% aqueous solution of potassium hydroxide at room temperature for 1 minute and 30 seconds, washed with water, drained, and then dried.
Post bake at 00 ° C. At this time, since the positive photoresist has low heat resistance, it is deformed during post-baking,
It has a forward tapered shape. Next, graphite dispersion GA-6
6M by spin coating at 10 rpm at 10 rpm.
Apply for about 1 μm thickness for 2 seconds. Next, drying is performed in a clean oven at 90 ° C. for 15 minutes. Next, after dissolving the photoresist with a 2% aqueous solution of potassium hydroxide for 1 minute, 3 kg
/ Water with a water pressure of / cm ² , draining, and curing in a clean oven at 200 ° C for 30 minutes. Thus, a glass substrate with a pixel partition film is completed. The completed pixel partition film has a shape obtained by inverting the underlying positive photoresist and has an inverted tapered shape. In the present invention, graphite by the lift-off method is used, but a material in which a metal oxide is dispersed instead of the carbon may be used. Alternatively, a stacked film of a conventional metal or a metal and a metal oxide, a stacked film of a metal and a metal nitride, or a stacked film of a metal, a metal oxide, and a metal nitride may be used. At this time, the pixel partition film pattern has a width of 20 μm, a pitch of 100 μm in width and 30 μm in height.
0 μm, numerical aperture 640 × (three colors) rows, and height 480.

Next, a colored layer forming step is started. In the present embodiment, the colored layer was formed by a film transfer method in which the colored layer was previously formed to a predetermined thickness on a base film serving as a support, and then transferred to a glass substrate by a lamination method. A 50 μm thick polyethylene terephthalate (PET) film was used as a base film support, and a cushion layer was formed thereon.
A two-layer film for CF manufactured by Hitachi Chemical Co., Ltd., in which a layer coated with 0 μm was used as a base film, and a 1.6 μm colored layer was coated thereon with a roll-to-roll. First, as a first color, a red film is bonded to a glass substrate on which a light-shielding layer is formed at a lamination temperature of 60 ° C., a lamination speed of 1.0 m / min, and a roll pressure of 3 kg / cm ² . Next, an exposure step is started. The exposure is performed by using a proximity exposure machine such that the colored layer side is supported by an exposure stage so that the glass substrate side of the substrate and the light-shielding film side of the photomask face each other. Here, the colored layer side does not necessarily need to be set on the exposure stage, and the back surface of the glass substrate may contact the exposure stage depending on the structure of the exposure machine. Next, the photomask and the substrate are aligned and 400 mj / 405 nm
cm2 was exposed. At this time, the opening of the photomask was arranged so as to overlap the opening of the light shielding layer by 6 μm on each side. This overlap amount may be any value within a range of -10 to 15 m. The gap between the substrate and the photomask was 60 μm. This gap amount is 0 to 500
Any value may be used as long as it is within the range. Next, the base film is peeled off, developed with an alkali developer, washed with water, drained, and then cured. This process is repeated for green and blue. The order of formation is not limited. After the three colors are formed, washing is performed, and an overcoat is formed thereon as necessary, thereby completing a color filter. FIG. 1 shows a cross-sectional view of the color filter thus produced.

In this embodiment, the colored layer is formed by a film transfer method. However, a coating liquid in which a pigment is dispersed so as to become red, blue and green is applied by a spin coater method, a wheeler method, a roll coater method or the like. It may be formed by a construction method.

[0014]

According to the method for manufacturing a color filter of the present invention, there is no concave portion between the pixel and the pixel partition film, and the surface is excellent in smoothness.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining the present invention.

FIG. 2 is a cross-sectional view for explaining an embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining a problem in a conventional method.

FIG. 4 is a sectional view of a liquid crystal display.

[Explanation of symbols]

 1. 1. Pixel partition film Glass substrate 3. Color pixels 4. Overcoat layer (O 5. Polarizer 6. ITO electrode 7. Color filter 8. Alignment film 9. Liquid crystal 10. Seal material 11. Top coat layer 12. ITO electrode 13. Glass substrate 14. Polarizer 15. Base film base 16. Exposure stage 17. Photo mask 18. Photo mask light-shielding film 19. Cushion layer 20. Base film 21. Depression 22. Photosensitive area 23. Active ray

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

Claims (1)

[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, characterized in that the pixel partition film is a film whose cross-sectional area increases as the distance from the translucent substrate surface increases.