JPH0949915A - Production of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a production method for a color filter having extremely small steps in the pixel of a color layer which makes alignment easy for exposure of a pattern by transferring a photosensitive color layer to a transparent substrate and exposing the photosensitive color layer through the side of the transparent substrate surface opposite to the surface where the photosensitive color layer is transferred. SOLUTION: A photosensitive color layer formed on a temporary supporting body is transferred to a transparent substrate 101 by a transfer method, and the photosensitive color layer is exposed to light for forming a pattern of color pixels through the back surface of the transparent substrate 101. By this exposure method, the light which hardens the photosensitive color layer 103 passes only the space where no black light-shielding layer 102 is formed. By exposing the photosensitive color layer 103 with the light passing through the space in the black light-shielding layer 102 and then developing the pattern, no overlap is produced between the photosensitive color layer 103 and the black light- shielding layer 102. Thereby, steps in a pixel produced by waves in the photosensitive color layer 102 can be suppressed to be as small as possible.

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.

[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. 3, a color filter for displaying an LCD in color is R (red) G (green) on a substrate 2 such as a glass plate on which a BM (black matrix) 1 having a grid pattern is formed. ) B (blue) color pixels 3 (about 100 × 100 × 2 μm) are sequentially formed, and a transparent overcoat layer (OC) 4 is formed thereon. 5 is a polarizing plate and 6 is 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 seal 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, the number of steps is large and the cost is high. Further, since a dye is used as a coloring agent, there is a disadvantage that reliability (weather resistance and heat resistance), which is an important issue of a color filter, is inferior.
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. For photolithography, liquid resists and films are contemplated. In the liquid resist, color pixels are formed by applying a varnish in which a pigment is dispersed in a photosensitive resin on a glass substrate with a spinner, drying, exposing, and developing. On the other hand, the film is a varnish formed into a film like the photosensitive film for printed boards, and after being laminated on a substrate, color pixels are formed by exposure and development.

In the manufacture of color filters for LCD,
A method for forming a photosensitive resin layer by transferring a photosensitive colored layer provided on a temporary support onto a transparent substrate having a black light-shielding layer is disclosed in Japanese Patent Laid-Open No. 61-99 as a film transfer method.
102, JP-A-63-187203, JP-A-2-239205 and the like.

As a transfer film having a photosensitive colored layer provided on a temporary support, a single layer type shown in JP-A-7-79937, or a multilayer type shown in JP-A-59-97138. Are used.

[0009]

A light shielding layer such as a black light shielding layer formed on the surface of a transparent substrate has a predetermined thickness. When the photosensitive coloring layer formed on the temporary support is transferred onto such a substrate surface, the undulation as shown in FIG. 2 occurs due to the step between the portion where the black light shielding layer is formed and the portion where the black light shielding layer is not formed. FIG. 2 is a cross-sectional view showing a state of a step inside the pixel when the pixel is formed by exposure from the upper surface of the substrate (the surface of the substrate on which the photosensitive coloring layer is transferred).
Is a substrate, 102 is a black light shielding layer, and 103 is a photosensitive colored layer. When pattern exposure and development are performed from the upper surface of the substrate (the surface of the substrate on which the photosensitive coloring layer is transferred) to this wavy surface, the height of the portion where the light shielding layer and the photosensitive coloring layer overlap is high. Therefore, a large step difference (Δh in FIG. 2) occurs in the pixel. Further, in the pattern exposure from the upper surface of the substrate, if the relative positions of the substrate and the mask are slightly deviated from each other, a step in the pixel having a different shape or a white spot may occur.

The change in the shape of the step inside the pixel for each substrate is a big problem in quality control of the product. In addition, the occurrence of a large step in the pixel not only means that the coloring performance varies in the pixel, but also affects the alignment of the liquid crystal molecules and causes the distribution of the applied voltage. The present invention relates to an LCD
Provided is a method for manufacturing a color filter that minimizes a step in a pixel of the color filter that greatly affects the coloring performance of the color filter and the display quality of the LCD panel.

[0011]

According to the present invention, a photosensitive colored layer provided on a temporary support is transferred onto a transparent substrate on which a light-shielding layer is formed with a predetermined gap, and exposure and development are performed to obtain a predetermined color. In the method for manufacturing a color filter for forming a colored layer, the photosensitive colored layer transferred to the transparent substrate is exposed from the transparent substrate surface side opposite to the surface on which the photosensitive colored layer is transferred. This is a method of manufacturing a color filter.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention exposes a photosensitive colored layer formed by transfer on a substrate having a light shielding layer from the back surface of the substrate (the surface of the substrate opposite to the surface on which the photosensitive colored layer is transferred). By repeating the steps of developing and drying a plurality of times, an LCD color filter having an image of a plurality of colors is manufactured.

In the present invention, the photosensitive colored layer formed on the temporary support is transferred onto the surface of the substrate by a transfer method, and then pattern exposure for forming colored pixels is performed from the rear surface of the substrate. According to such an exposure method, the light for curing the photosensitive colored layer is transmitted only through the gap portion where the light shielding layer is not formed. If the photosensitive colored layer is exposed and developed with light that has passed through the gaps of the light-shielding layer, the above-described overlapping of the light-sensitive colored layer and the light-shielding layer does not occur, and pixels that are generated due to the waviness of the light-sensitive colored layer The inner step can be minimized.

FIG. 1 is a cross-sectional view showing a state of a step inside a pixel when back exposure is performed, wherein 101 is a substrate, 102 is a black light shielding layer, and 103 is a photosensitive coloring layer. In this case, since the exposure and the development are performed along the interface of the light shielding layer such as the black light shielding layer, there is no overlap between the photosensitive coloring layer and the black light shielding layer. Therefore, the step difference Δh ′ in the pixel when the back surface exposure is performed can be suppressed to be smaller than the Δh shown in FIG.

In order to more completely block the exposure light by the light shielding layer, in a polymer in which carbon powder (for example, carbon powder (amorphous carbon powder) or graphite powder) is dispersed to form a black light shielding layer. You may add a ultraviolet absorber to. The light shielding layer can also be formed of a metal such as chrome.

In order to suppress the step in the pixel of the color filter, it is also effective to suppress the undulation of the photosensitive resin layer that occurs when the photosensitive resin layer is transferred from the temporary support to the substrate surface. For that purpose, the transfer pressure is 2 to 12 kgf / c.
The transfer is preferably performed at a constant pressure of m2, more preferably 4 to 8 kgf / cm2. If the thickness of the photosensitive colored layer is sufficiently larger than the thickness of the black light-shielding layer, the waviness of the photosensitive colored layer is alleviated by the flow of the photosensitive colorant, and the occurrence of the step inside the pixel can be suppressed. The greater the thickness of the photosensitive colored layer is than the thickness of the light shielding layer, the greater the effect of suppressing the waviness of the photosensitive colored layer.
It was confirmed that the thickness of the light shielding layer is preferably 0.7 or less when the thickness of the photosensitive coloring layer is 1, in order to suppress the step difference in the pixel to 0.3 μm or less.

[0017]

【Example】

Example 1 Corning 7059 glass (200 mm long) was used as the transparent substrate.
mm, width 300 mm, thickness 1.1 mm) was used. A light-shielding layer was formed thereon by a lift-off method using a graphite light-shielding layer forming graphite dispersion (Hitasol GA66M) manufactured by Hitachi Powder Metallurgy. Considering the thickness of the photosensitive colored layer to be transferred, the thickness of the light shielding film is 0.8 μm and 1.0 μm.
m, 1.2 μm, and 1.5 μm. A photosensitive coloring layer is applied on a temporary support and dried, and then used as a transfer film. The coating of the photosensitive colored layer was performed by the gravure roll coating method. The thickness of the photosensitive resin layer was 1.5 μm for all RGB colors. First, surface treatment is performed on the glass substrate provided with the black light shielding layer. The black light-shielding layer is formed by a line having a thickness of 24 μm, and the gap between the light-shielding layers to be pixels is a rectangle of 276 × 76 μm. The surface treatment was performed by irradiating UV light from the upper surface of the substrate at room temperature for 5 minutes. The first color (R) is transferred onto the upper surface of the glass substrate having the black light-shielding layer by a laminating method using a transfer film having a photosensitive colored layer provided on the temporary support. Lamination was performed under the following constant conditions regardless of the thickness of the black light shielding layer provided on the glass substrate surface. Substrate temperature 100 [° C] Laminator roll temperature 130 [° C] Laminator roll pressure 5 [kgf / cm2] Laminator roll feed rate 0.5 [m / min] Photosensitive coloring with the transfer film laminated on the substrate glass Perform a pattern exposure to cure the layer. The exposure machine used was a parallel exposure machine manufactured by Dainippon Screen. The exposure amount was 500 mJ / cm 2, and in order to confirm the effectiveness of the backside exposure method, the exposure from the top surface of the substrate was also performed. Subsequently, a predetermined colored image was formed by spray development using an alkaline aqueous solution, and the image was stabilized by heat curing. Table 1 shows the measurement results of the step difference in the pixel for the image of the first color of the color filter thus formed.

[0018]

[Table 1] In-pixel step of first color image Thickness of light-shielding layer (μm) In-pixel step Δh (μm) Back exposure Exposure from the top surface of substrate 0.8 0.22 0.45 1.0 0.25 0.48 1.2 0.33 0.50 1.5 0.35 0.53 Subsequently, the second color (G) of the photosensitive colored layer was transferred. Regarding the transfer conditions, the substrate temperature and the laminator roll temperature were set slightly lower than when transferring the first color (R) photosensitive colored layer, and the transfer conditions were as follows. Substrate temperature 90 [° C] Laminator roll temperature 110 [° C] Laminator roll pressure 5 [kgf / cm2] Laminator roll feed rate 0.5 [m / min] For the second color image of the color filter, as with the first color Exposure, development, and heat curing were performed. The exposure was performed by irradiating 800 [mJ / cm 2] as a proper exposure amount. The exposure was performed from the top surface of the substrate and the back surface exposure, and almost the same results as in the case of the first color were obtained. Table 2 shows the measurement results of the step inside the pixel.

[0019]

[Table 2] Step in pixel of second color image Thickness of light-shielding layer (μm) Step in pixel Δh (μm) Back exposure Exposure from the top surface of substrate 0.8 0.28 0.50 1.0 0.29 0.53 1.2 0.35 0.55 1.5 0.45 0.60 Next, the photosensitive color layer of the third color (B) was transferred. The transfer conditions were the same as those for the second color image, and the exposure amount, the developing conditions, and the heat curing were the same as those for the second color. Table 3 shows the measurement results of the step difference within the third color pixel.

[0020]

Table 3 In-pixel step of the third color image Thickness of light-shielding layer (μm) In-pixel step Δh (μm) Back exposure Exposure from the top of the substrate 0.8 0.27 0.50 1.0 0.29 0.52 1.2 0.34 0.53 1.5 0.35 0.60 In normal exposure from the upper surface of the substrate, due to the problem of alignment accuracy of the mask pattern at the time of exposure, compared to the case of performing exposure from the back surface. The variation (standard deviation) of the step difference in the pixel due to the sample is large. Further, when an exposure amount far exceeding the appropriate exposure amount was applied, there was a phenomenon in which the photosensitive colored layer remained in the pixel portion where the exposure was not planned due to the scattering of the exposure light in the glass substrate.

Example 2 Corresponding the thickness of the black light shielding layer formed on the glass substrate to the thickness of the photosensitive coloring layer, the thickness of the photosensitive coloring layer was 1.0 μm.
m, the thickness of the black light shielding layer is 0.5 μm, 0.7 μm,
When the thickness of the photosensitive colored layer is 2.0 μm, the black light-shielding layer has a thickness of 1.0 μm and 1.
The thickness was 4 μm, 2.0 μm, and 2.4 μm, and the photosensitive colored layer was exposed and developed in the same manner as in Example 1 to form a colored layer. When the in-pixel step was measured, it showed the same tendency as in Example 1, and the in-pixel step was 0.3 μm by setting the thickness of the black light-shielding layer to 70% or less of the thickness of the photosensitive coloring layer. It was confirmed that the following can be done.

Example 3 Using a multilayer structure transfer film (polyethylene terephthalate film / copolymer layer of polyvinyl methyl ether and maleic anhydride / photosensitive coloring layer), the photosensitive coloring layer was exposed in the same manner as in Example 1, It was developed to form a colored layer.
When the step difference in the pixel was measured, the same tendency as in Example 1 was obtained.

[0023]

According to the color filter manufacturing method of the present invention, the steps in the pixels of the obtained color filter colored layer are very small, and the alignment during pattern exposure is easy.

[Brief description of drawings]

FIG. 1 is a sectional view of a color filter showing a state of a step inside a pixel when a pixel is formed by backside exposure according to the present invention.

FIG. 2 is a cross-sectional view of a color filter showing a state of a step inside a pixel when the pixel is formed by exposure from the upper surface of the substrate.

FIG. 3 is a sectional view of a liquid crystal display.

[Explanation of symbols]

 1. 1. BM (black matrix) Glass substrate 3. Color pixels 4. 4. Overcoat layer (OC) Polarizing plate 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. Polarizing plate 101. Transparent substrate 102. Black light shielding layer 103. Photosensitive colored layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Itabashi 48 Wadai, Tsukuba, Ibaraki Pref., Hitachi Chemical Co., Ltd. Tsukuba R & D Labs.

Claims (3)

[Claims] 1. A photosensitive coloring layer provided on a temporary support is transferred onto a transparent substrate on which a light shielding layer is formed with a predetermined gap,
In the method of manufacturing a color filter in which a predetermined colored layer is formed by exposure and development, the photosensitive colored layer transferred to the transparent substrate is placed on the transparent substrate surface side opposite to the surface on which the photosensitive colored layer is transferred. A method for manufacturing a color filter, which comprises exposing from a light source. 2. The method for producing a color filter according to claim 1, wherein the thickness of the light shielding layer is 70% or less of the thickness of the photosensitive colored layer formed by transfer. 3. The method for producing a color filter according to claim 1, wherein the light shielding layer is a black light shielding layer made of a polymer in which carbon powder is dispersed.