JPH08278497A - Color filter and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a color filter with improved smoothness. [Structure] Colored layers 32 of R, G, and B are formed on one main surface of a glass substrate 31. Glass substrate 31 and colored layer 32 of colored layer 32
The taper angle formed by the outer edges of and is a reverse taper. Glass substrate
On the 31 and the colored layer 32, apply a black photoresist,
After the entire surface of the other main surface of the glass substrate 31 is exposed, the black photoresist of the light shielding layer 33 on the colored layer 32 which is not exposed by the back surface exposure is developed. The black photoresist on the upper surface of the colored layer 32, which serves as a mask for the colored layer 32 itself during UV light irradiation, is removed to form a light-shielding layer 33 in the form of a plane lattice between the colored layers 32. A resin is applied, baked, and thermally cured to form the overcoat layer 34. Silicon oxide (SiO ₂ ) film 35,
An ITO film is continuously formed, and the ITO film is patterned by a photolithography method to form a transparent electrode 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter having a light shielding layer between colored layers.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have the great advantages that they are thin and lightweight, can be driven at a low voltage, have low power consumption, and can display large panels. It is widely used as a display device such as an office automation device such as a word processor or a personal computer and a television receiver, and high performance such as smoothness, positional accuracy, and appearance quality is required for a color filter.

A color liquid crystal display device is classified into a simple matrix type and an active matrix type according to a driving method, and each of them uses a color filter, which will be described with reference to the drawings. .

As shown in FIGS. 3 and 4, a light-shielding layer 2 is formed on a glass substrate 1 in a predetermined pattern by a photolithography method. The light-shielding layer 2 has a grid pattern and chromium (Cr). ) Or nickel (Ni) or the like and a metal thin film having a thickness of about 1000 to 2000 angstroms.

On the light-shielding layer 2, a colored layer 3 composed of three primary colors of red (R), green (G) and blue (B) is formed, and ITO (Indium Tin Oxide) is formed on the colored layer 3. Transparent conductive film 4 is formed. Here, the light shielding layer 2
Is provided in the gap portion of the colored layer 3 which becomes the pixel portion for the purpose of improving the contrast of screen display and protecting the thin film transistor of the active matrix from external light. Note that C
The light-shielding layer 2 made of a metal thin film such as r or Ni is 1000
Even if the thickness is about 2000 angstroms, the optical density is 3 to 4, which is a very excellent light shielding property.

However, since the vacuum technique is used when the light-shielding layer 2 is formed, the equipment investment is large, the throughput is poor, the cost is high, and the metal thin film of the light-shielding layer 2 becomes a reflector, so that the face is visible. Or the reflection of outside light lowers the contrast.

For this reason, there is known a color filter shown in FIG. 5, which does not use a metal thin film for the light shielding layer.

The color filter shown in FIG. 5 is a light-shielding layer in which a black pigment is dispersed in a photosensitive resin on a glass substrate 11.
12 is formed in a predetermined pattern, a colored layer 13 is formed between the light shielding layers 12, and a transparent conductive film 14 is formed on the light shielding layers 12 and the colored layers 13. The light-shielding layer 12 as described above is superior to the light-shielding layer 2 made of a metal film in that it does not serve as a reflector, does not use a vacuum technique, and does not require etching, and thus is excellent in cost, but has a light-shielding property. In order to obtain the same optical density as the light-shielding layer 12 composed of a metal thin film,
When the colored layer 13 is formed on the light-shielding layer 12, the film immediately above the light-shielding layer 13 protrudes, so that the flatness required for the color filter of the liquid crystal display device cannot be maintained.

On the other hand, in a color filter used in a simple matrix type liquid crystal display device, conventionally, a light shielding layer made of a layer in which a black pigment is dispersed in a photosensitive resin is formed in a stripe shape on a glass substrate, R, G,
The type in which a colored layer consisting of the three primary colors of B is formed has been widely used, but due to the demand for improvement in display quality such as contrast, a light-shielding layer in which a black pigment is dispersed in a photosensitive resin on a glass substrate has a grid pattern. A color filter of the type formed in is known.

Also in this case, as in the case of the color filter shown in FIG. 3 described above, the flatness required for the color filter of the liquid crystal display device cannot be maintained. Particularly, in a color filter used in a simple matrix type liquid crystal display device, it is 0.05 μm or less, preferably 0.01 μm.
Flatness is required to some extent, which is an important issue that needs improvement.

As a color filter for improving flatness, for example, the structure shown in FIG. 6 is known.

In the color filter shown in FIG. 6, the colored layers 22 of R, G and B are first formed on the glass substrate 21, and then the entire surface from the back surface by self-alignment using the pixels of the colored layer 22 as a mask. Light-shielding layer 23 between the colored layers 22 by exposure
And an overcoat layer 24, a silicon oxide (SiO ₂ ) layer 25, and a transparent electrode 26 of ITO (Indium Tin Oxide).

[0013]

[Problems to be solved by the invention] However,
When the taper angle of the colored layer 22 of each color of R, G and B, that is, the angle formed by the outer edges of the glass substrate 21 and the colored layer 22 is smaller than 90 ° as conventionally used, when exposing the light shielding layer 23 from the back surface. In addition, since the colored layer 22 becomes a light absorbing layer, photocrosslinking by exposure of the light shielding layer 23 in the portion in contact with the colored layer 22 is not sufficiently performed, and the light emitting layer is missing during development, and the colored layer 22 and the light shielding layer 23. A gap is formed between the and, which becomes a factor that hinders smoothness.

Further, in a color filter for an active matrix type liquid crystal display device, it is often used that a transparent conductive film is directly provided thereafter without interposing a protective film, but the transparent conductive film may be broken. Also has some problems.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a color filter in which the smoothness of the color filter is improved and a manufacturing method thereof.

[0016]

A color filter according to claim 1 is provided with a transparent substrate, a plurality of colored layers formed on the transparent substrate with a gap therebetween, and the back surface exposure provided in the gap between these colored layers. In the color filter having a light-shielding layer, the coloring layer has an inverse taper taper angle.

According to a second aspect of the present invention, in the color filter according to the first aspect, the light shielding layer is formed in a lattice shape.

According to a third aspect of the present invention, there is provided a method of manufacturing a color filter, wherein a step of forming a colored layer in a reverse taper shape on one main surface of a transparent substrate, a step of applying a black resist on the colored layer, and the black step. Exposing the resist from the other main surface side of the transparent substrate.

[0019]

According to the present invention, since the taper angle of the colored layers is an inverse taper, the gap between the colored layers is exposed by the back surface exposure.
When the light-shielding layer is formed, light reaches the entire region of the light-shielding layer that needs to be photo-crosslinked, so that a sufficient photocrosslinking reaction occurs, and the light-shielding layer does not drop off at the end of the opening during development. Therefore, smoothness can be obtained without causing a step.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color filter according to an embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a photosensitive pigment dispersion transfer film is heat-treated on one main surface of a glass substrate 31 as a transparent substrate of 7059 manufactured by Corning Co. having a plate thickness of 0.7 mm or 1.1 mm. Laminate, expose and develop islands corresponding to picture elements using photolithography method,
The colored layer 32 is formed. At this time, the taper angle of the colored layer 32,
That is, since the angle formed by the outer edges of the glass substrate 31 and the colored layer 32 is inversely tapered, the exposure amount is reduced, and preferably 70 mj
After being exposed to light at a density of less than 1 cm ² / cm ² , the colored layer 32 is formed by developing with an alkaline aqueous solution having a pH of about 10.5. The colored layer 32 is repeated for each color to obtain the R, G, and B colored layers 32. The taper angle of each colored layer 32 is such that R is 95
°, G is 110 °, and B is 100 °.

Next, on the glass substrate 31 and the colored layer 32,
For example, BK-5000 manufactured by Fuji Hunt Co., Ltd. is applied as a black photoresist by a coating method such as a spin coating method, a roll coating method, or a printing method, and prebaking is performed at 90 ° C. for 5 minutes. Then, after the entire surface of the other main surface of the glass substrate 31 is exposed with an exposure amount of, for example, 500 mj / cm ² , the black photoresist of the light shielding layer 33 on the colored layer 32 which is not exposed by the back surface exposure is adjusted to pH 1.
Develop with the developer of 1.8. By this development, the black photoresist on the upper surface of the colored layer 32, which serves as a mask for the colored layer 32 itself when the UV light is irradiated, is removed, and the light shielding layer 33 in the form of a plane lattice is formed between the colored layers 32. And after this,
Post-prebaking is performed at 150 ° C. for 30 minutes to complete the light shielding layer 33.

Further, the overcoat layer 34 is formed by applying a resin such as an acrylic resin or an epoxy resin in a thickness of 1 to 2 μm by spin coating, baking and thermosetting.

After forming these, a silicon oxide (SiO ₂ ) film 35 and an ITO (Indium Tin Oxide) film are continuously formed, and finally the ITO film is patterned into a predetermined pattern by a photolithography method. The transparent electrode 36 is formed.

The thus obtained multicolor liquid crystal display device for STN has no leakage of light from the gaps of the color filters, and the contrast is greatly improved. 1 step difference compared to taper
/ 10, and a color filter with excellent smoothness can be obtained. The taper angle of the colored layer of the comparative example is R = 75 °,
G was 85 ° and B was 80 °.

[0026]

[Table 1] Next, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 2 is, for example, 0.7.
mm or 1.1 mm plate thickness made by Corning Co. 70
On one main surface of the glass substrate 31 of 59, a photosensitive resin in which 20% by weight of a red organic facial organic material is dispersed is applied by a spinner, and the solvent is volatilized to some extent while being kept at room temperature for 3 minutes. Pre-bake for 5 minutes, about 100m
It is exposed at j / cm ² . After that, 50 ℃, pH 10.5
Spray develop with alkaline solution for 60 seconds,
After baking at 1 ° C. for 1 hour, the R colored layer 32 is formed. At this time, since the taper angle is an inverse taper, the spray pressure at the time of development is set high, for example, 0.6 kg / cm ² or more.

The G colored layer 32 and the B colored layer 32 are formed in the same manner. At this time, the taper angle of each colored layer 32 is 95 ° for R, 105 ° for G, and 100 ° for B.
Met.

Then, a photosensitive material in which carbon black is mixed with a negative resist is applied on the entire surface of the colored layer 32, and the photosensitive material is exposed from the other main surface of the glass substrate 31 using the colored layer 32 as a photomask. . Develop the photosensitive material,
The light-shielding layer 33 is formed so as to remain only in the gap between the colored layers 32, 32, and the silicon oxide film 35 is formed by a sputtering method.
A transparent electrode 36 of a transparent conductive film made of ITO is formed.

The color filter thus obtained does not cause a step between the colored layer 32 and the light shielding layer 33 and is excellent in smoothness and can be sufficiently used as a color filter for a thin film transistor.

[0031]

According to the present invention, since the taper angles of the colored layers are inversely tapered, when the light shielding layer is formed in the gap between the colored layers by backside exposure, the light shielding layer needs to be photo-crosslinked. Since light reaches the entire area of the film uniformly, a sufficient photocrosslinking reaction occurs, the light-shielding layer does not drop off at the edge of the opening during development, no step is generated, and smoothness is obtained. Even when used in a device, a high quality display quality can be obtained without disturbing the alignment of the liquid crystal.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a color filter according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a color filter of another embodiment.

FIG. 3 is a perspective view showing a conventional color filter.

FIG. 4 is a sectional view of the same.

FIG. 5 is a sectional view showing another conventional example of the same.

FIG. 6 is a sectional view showing another conventional example of the above.

[Explanation of symbols]

 31 Glass substrate as a transparent substrate 32 Colored layer 33 Light-shielding layer

Claims (3)

[Claims] 1. A color filter having a transparent substrate, a plurality of colored layers formed on the transparent substrate via a gap, and a light-shielding layer provided on the gap between the colored layers by backside exposure, wherein the colored layer is A color filter having a reverse taper angle. 2. The color filter according to claim 1, wherein the light shielding layer is formed in a lattice shape. 3. A step of forming a colored layer in an inversely tapered shape on one main surface of the transparent substrate, a step of applying a black resist on the colored layer, and a step of applying the black resist to the other main surface side of the transparent substrate. The method of manufacturing a color filter, comprising: