JPH08292426A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE: To make it possible to produce a color liquid crystal display device which has patterning spacers having adhesive strength as gap holders of a liquid crystal display device of an STN type ferroelectric type and liquid crystal display of antiferroelectric type liquid crystals particularly requiring gap accuracy, has excellent flatness of color filter parts and is formed by using color filter substrates having high-strength leader electrodes on glass. CONSTITUTION: This liquid crystal display device has a substrate 5 to be provided with color filters 4 and a black matrix 3, overcoating films 21 to be disposed on these color filters 4 and transparent conductive films to be disposed on these overcoating films 21. The overcoating films 21 have projections 22. These projections 22 are formed as the patterning spacers acting as the cell gap holders.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a liquid crystal display device having a color filter covered with a photosensitive overcoat film having a patterning spacer simultaneously formed by the photosensitive overcoat film, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As a manufacturing method for uniformly forming a cell gap of a liquid crystal display device for color display, there are a spacer dispersion method and a patterning spacer method.

In this spacer dispersion method, spacers having a uniform particle size as a cell gap retaining agent are evenly dispersed with alcohol or water on one of a pair of substrates sandwiching a liquid crystal and dispersed as a cell gap retaining agent. Then, the cell gap is formed uniformly.

Further, in the patterning spacer method, a patterning spacer film having a cell gap thickness is formed on the entire surface of a substrate on which a transparent conductive film is patterned and formed as a cell gap maintaining agent, and patterning is performed by using a photolithography technique to make the cell gap uniform. Is formed.

This latter patterning spacer method is generally formed on one of a pair of substrates holding a liquid crystal.

In order to form the patterning spacer on the color filter substrate side, an overcoat film is formed on the color filter. Then, a transparent conductive film is formed on the overcoat film, and the transparent conductive film is patterned.

Then, a method of forming a patterning spacer film on the entire surface of the substrate by a spin coating method and then patterning is generally used.

In order to form the patterning spacer on the counter substrate side, which is not the color filter side, a transparent conductive film is formed on the substrate, and then the transparent conductive film is patterned.

After that, a method of forming a patterning spacer film on the entire surface of the substrate by a spin coating method and then patterning is used.

As described above, a photolithography process for forming patterning spacers on either one of the pair of substrates is required.

A method in which a patterning spacer film is formed on a substrate having a transparent conductive film patterned on the color filter side by a spin coating method, and then patterning is performed,
This will be described with reference to FIGS. 7, 8, 9, 10, and 11.

7 to 11 are sectional views showing a method of forming a patterning spacer by forming a transparent conductive film by patterning after forming an overcoat film on a color filter and using a negative photosensitive patterning spacer film. Is. 11 shows a plan view of the patterning spacer.

First, as shown in FIG. 7, a black matrix 3 for improving color display performance is formed. After that, the overcoat film 2 is formed on the entire surface of the substrate 5 having the color filter 4 formed thereon by a spin coating method.

Here, the overcoat film 2 has chemical resistance of the color filter against acids, alkalis, organic solvents, etc., sputtering resistance for forming a transparent conductive film by sputtering, and further has unevenness of the color filter. It is desirable to have a role of flattening.

After that, the transparent conductive film 7 is formed on the entire surface of the overcoat film 2 by the sputtering method. After that, a transparent conductive film is patterned by using a photo mask.

After that, as shown in FIG. 8, a patterning spacer film 6 having photosensitivity is formed on the entire surface of the patterned transparent conductive film 7 by a spin coating method.

After that, as shown in FIG. 9, the patterning spacer film 6 having photosensitivity is exposed by using a photomask 1b for forming the patterning spacer 6.

After that, as shown in FIG. 10, the exposed photosensitive patterning spacer film is subjected to a development process, and the patterning spacer 61 is patterned by photolithography.

As shown in the plan view of FIG. 11, the patterning spacer 61 is formed in the space portion of the transparent conductive film 7 on the black matrix 3 at the corner portion of each pixel of the color filter 4. Then, the patterning spacer 61 plays a role as a cell gap maintaining agent.

Thereafter, as shown in FIG. 10, an alignment film 8 for aligning the liquid crystal is formed, and as the alignment treatment, generally, the alignment film is made of a cloth such as cotton or rayon and rotated in a certain direction by friction. Alignment treatment is performed by a rubbing method in which scratches are formed on the surface of the alignment film 8 by rubbing with force.

Thereafter, as shown in FIG. 12, a substrate provided with a patterning spacer 1 with a uniform thickness on the entire surface of the display pixel and a counter substrate are overlapped with each other to form a uniform cell gap for sandwiching the liquid crystal. Can be formed.

[0022]

In order to form a liquid crystal display cell by a conventional manufacturing method, in order to form a flat and uniform cell gap for holding a liquid crystal between a pair of substrates, a uniform particle size is required. One more process is required to uniformly disperse the spacers on the substrate or a photolithography process to form the patterning spacers.

Further, the spacer spraying method has a drawback that the spacers are randomly scattered on the substrate, so that the spacers are scattered in the color filter pixel portion, and the spacers are partially aggregated to make it difficult to obtain a uniform cell gap size.

Furthermore, the patterning spacer 61 formed by the conventional manufacturing method forms an interface between the transparent conductive film 7 and the underlying overcoat layer 2 in order to be formed after the transparent conductive film 7 is patterned. In the form that exists.

The underlying overcoat layer 2 is a transparent conductive film 7.
Is formed by sputtering, it is exposed to a high temperature of about 200 ° C.

Therefore, even if the surface of the overcoat layer 2 is altered and the patterning spacer 61 of the same material as the underlying overcoat layer 2 is formed on the surface by the photolithography process, the adhesion strength of the patterning spacer can be obtained. It has the drawback of being difficult.

Therefore, the alignment treatment method after coating the alignment film for aligning the liquid crystal is a rubbing method in which a rotational frictional force is applied to the alignment film with a cloth such as cotton or rayon. The patterning spacers are peeled off or come off.

Therefore, when the patterning spacer 61 is formed by the conventional technique, the method of aligning the alignment film for aligning the liquid crystal has a problem that the rubbing method is unstable and cell defects are likely to occur.

It is an object of the present invention to solve the above problems and to form a structure of a liquid crystal display device having a color filter which does not cause peeling or falling defects of the patterning spacer when forming the patterning spacer by patterning. It is to provide a manufacturing method for doing.

[0030]

In order to achieve the above object, the structure of the liquid crystal display device of the present invention and the manufacturing method for forming this structure adopt the following means.

The liquid crystal display device of the present invention comprises a substrate provided with a color filter and a black matrix, an overcoat film provided on the color filter, and a transparent conductive film provided on the overcoat film, and the overcoat film has projections. The projection spacer is used as a patterning spacer that functions as a cell gap maintaining agent.

In the method of manufacturing a liquid crystal display device of the present invention, a step of forming a black matrix on a substrate, a step of forming a color filter, a photosensitive overcoat film is formed on the entire surface, and the overcoat film is formed. A two-step exposure process using two photomasks; a development process to form protrusions on the photosensitive overcoat film to simultaneously form an overcoat film and a patterning spacer in the color filter region; and a transparent conductive film. And a step of patterning the film.

[0033]

The overcoat film formed on the color filter is preferably made of a material which has excellent flatness for alleviating irregularities in the color filter region, and further has chemical resistance and transparent conductive film sputtering resistance.

Furthermore, since the photosensitive overcoat film has the above-mentioned characteristics, it can be used as a patterning spacer.

When patterning the patterning spacers by a usual method, the transparent conductive film is formed on the overcoat film as described above, the transparent conductive film is patterned, and then the patterning spacer film is formed on the entire surface of the substrate, and then the patterning spacer film is formed. After exposure using a photomask, development processing is performed to form patterning spacers.

Since the patterning spacer thus formed has an interface with the overcoat film, it is difficult to obtain adhesion strength, and after the alignment film for aligning the liquid crystal is coated, the rubbing method is used as the alignment treatment. When,
It cannot withstand the frictional force and peels off or falls off.

According to the present invention, the photosensitive overcoat film and the patterning spacer are exposed to light in two steps using two photomasks, and then developed to form the photosensitive overcoat film and the patterning spacer at the same time. For example, a patterning spacer having no interface between the overcoat film and the patterning spacer can be obtained.

After that, a transparent conductive film is formed, and the transparent conductive film is patterned using a photomask in which the transparent conductive film portion of the convex portion of the patterning spacer is formed as a space. A patterning spacer having a thickness and capable of withstanding the rubbing frictional force can be obtained.

Therefore, in the cell assembling process, the spacer spraying process as the cell gap maintaining agent can be omitted, and the color liquid crystal display device having the color filter substrate excellent in flatness can be manufactured with a high yield.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. 1, 2, 3, and 4 are cross-sectional views showing a method of manufacturing a liquid crystal display device according to an embodiment of the present invention, and FIG. 5 is a photosensitive overcoat film and patterning of the liquid crystal display device shown in FIG. FIG. 6 is a perspective view showing a state in which a transparent conductive film is formed by patterning on a spacer. FIG. 6 is a graph showing the change in film thickness showing the relationship between the exposure light amount and the residual film ratio of the photosensitive overcoat film used in the present invention. Hereinafter, description will be given by alternately referring to FIGS. 1, 2, 3, 4, 5, and 6.

First, the structure of the liquid crystal display device according to the embodiment of the present invention will be described with reference to FIGS. 4 and 5. The color filter 4 is provided on the substrate 5 of the liquid crystal display device of the present invention.
And the black matrix 3 are provided.

Further, a photosensitive overcoat film 2 is provided on the color filter 4, and a transparent conductive film 7 is provided on the overcoat film 2.

The overcoat film 2 has projections, and these projections serve as a patterning spacer having a function as a cell gap maintaining agent.

Next, a manufacturing method for forming this structure will be described. An exposure method for forming protrusions on the photosensitive overcoat film, which is a feature of the liquid crystal display device of the present invention, will be described with reference to FIGS. 1, 2, 3, 4, and 5.

As shown in FIG. 1, the substrate 5 made of glass is used.
A photosensitive overcoat film 2 having photosensitivity was formed on the entire surface of the substrate by a spin coating method on the substrate on which the black matrix 3 and the red (R), green (G) and blue (B) of the color filter 4 were formed. After that, the first photomask 1a is used to perform an exposure process on the region of the photosensitive overcoat film 21.

The exposure amount of the first photosensitive overcoat film 21 having photosensitivity is smaller than the exposure amount at which the photosensitive overcoat film 2 is sufficiently photo-cured.

Next, as shown in FIG. 2, the second photosensitive overcoat film 22 is formed by using the second photomask 1b.
Exposure processing is performed on the area. The exposure amount of the second photosensitive overcoat film 22 is such that the photosensitive overcoat film 2 is sufficiently photo-cured.

After that, when a developing treatment is carried out in an alkaline developing solution, the region of the photosensitive overcoat film 21 is insufficiently photocured as shown in FIG. 3, so that the photosensitive material of the present invention shown in the graph of FIG. From the residual film ratio of the overcoat film having the property, the film thickness is reduced corresponding to the exposure amount and the development is performed. On the other hand, in the region of the second photosensitive overcoat film 22, the film thickness does not decrease because the photo-curing is sufficient.

The relationship between the exposure amount and the residual film ratio of the photosensitive overcoat film of the present invention shown in FIG. 6 is a phenomenon caused by a peak in the low wavelength region where the photosensitive wavelength of the overcoat film is 350 nm or less. is there. In order to form a pattern even in an exposure amount region where the photo-curing is insufficient, it is necessary to strictly control the wavelength generated by the exposure device, the pre-baking condition of the photosensitive overcoat film and the alkali developing condition.

As a result, the overcoat film 2 can be formed with a projection made of the second overcoat film 22 so as to project from the first overcoat film 21.

As shown in FIG. 5, the second overcoat film 22 serving as a protrusion can serve as a patterning spacer.

As described above, the structure of the overcoat film having protrusions according to the present invention is controlled by controlling the conditions of the exposure process, the pre-baking process, the developing process and the photolithography process. It is possible to control the film thickness arbitrarily and form them simultaneously.

As a result, a new photolithography process can be omitted as a patterning spacer on either one of the two substrates for sandwiching the liquid crystal.

As a result, the first lower surface of the overcoat film is
The second overcoat film 22 having a columnar projection is formed as a patterning spacer in an integral structure having no interface with the overcoat film, while the overcoat film 21 of FIG. be able to.

After that, the transparent conductive film 7 is formed on the entire surface of the substrate 5 by the sputtering method, and then the display electrode 72 and the extraction electrode 71 are formed by patterning.

By forming the patterning spacers located in the display electrode portion in the display electrode space portion, the patterning spacer functions as a cell gap retaining agent, and since the extraction electrode portion is formed on the substrate 5 made of glass, the adhesion strength is improved. A high extraction electrode can be obtained.

Next, a method of manufacturing the liquid crystal display device according to the present invention will be described in detail with reference to FIGS. 1, 2, 3, 4, 5 and 6.

First, as shown in FIG. 1, in order to form the black matrix 3 for improving the color filter characteristics on the substrate 5 made of glass, chromium is formed to a thickness of 100 nm by the sputtering method.

After that, OFPR-800 manufactured by Tokyo Ohka Co., Ltd. as a positive type resist is formed on chromium by a spin coating method to a film thickness of 1.3 μm.

After that, exposure processing is performed using a photomask having a black matrix pattern and alignment marks for alignment, and further development processing is performed in an alkali developing solution at room temperature for 1 minute.

After that, the resist is baked at a temperature of 120 ° C. and etched using a chromium etching solution MPM-E30 manufactured by The Inktech Co., Ltd. to form a black matrix 3 made of chromium.

Thereafter, the color filter 4 is formed on the black matrix 3 of the substrate 5 in the order of red (R), green (G) and blue (B) by a dyeing method. The color filter 4 is formed with a film thickness of 1.5 μm.

Thereafter, a V-259PA film manufactured by Nippon Steel Chemical Co., Ltd. as a photosensitive negative overcoat film 2 having a transparent negative type is formed on the color filter 4 by a spin coating method. The photosensitive overcoat film 2 is formed with a film thickness of 3 μm.

Then, the photosensitive overcoat film 2 is baked at a temperature of 80 ° C. to remove the solvent contained in the photosensitive overcoat film 2.

Then, as shown in FIG. 1 using a proximity exposure apparatus, the first photomask 1a is used to expose the area of the first overcoat film 21 to 200 mj so as to form a cylindrical projection. The amount of exposure process is performed.

Thereafter, as shown in FIG. 1, a photosensitive overcoat film 2 is formed by using a second photomask 1b.
The area of the second overcoat film 22 serving as the lower layer is set to 500
The exposure process is performed with an exposure amount of mj or more.

Then, the overcoat film 2 having photosensitivity is developed in an alkali developing solution at room temperature for 1 minute.

As a result, from the film thickness variation curve of the photosensitive overcoat film shown in the graph of FIG. 6, the residual film ratio of 200 mj indicates that the area of the first overcoat film 21 remaining as the columnar protrusion is about. The thickness of 3 μm can be reduced by 40% to form a thickness of about 1.8 μm.

Further, as shown in FIG. 6, from the residual film rate of 500 mj in the film thickness change curve of the photosensitive overcoat film, the film thickness of about 3 μm is almost reduced in the region of the second overcoat film 22 of the lower layer. Without being formed, it can be formed to a thickness of about 3 μm.

As a result, the step corresponding to the first overcoat film 21 and the second overcoat of the columnar protrusion can serve as a patterning spacer.

After that, the first overcoat film 2 is formed.
The substrate 5 on which the first and second overcoat films 22 are formed
Is baked at a temperature of 200 ° C. for 1 hour in a nitrogen atmosphere.

As a result, the hardness of the first overcoat film 21 and the second overcoat film 22 is thermoset to obtain a pencil hardness of about 4H.

Then, as shown in FIG. 4, the transparent conductive film 7 is formed.
For example, indium tin oxide (ITO) having a film thickness of 300 n is formed by a sputtering method at a substrate temperature of 200 ° C.
It is formed by m.

After that, OFPR-800 manufactured by Tokyo Ohka Kabushiki Kaisha is formed on the transparent conductive film 7 as a positive resist by a spin coating method to a film thickness of 1.3 μm.

After that, as shown in FIG.
In order to form the extraction electrode 71 and the extraction electrode 71, a photomask in which a portion of the lower second overcoat film 22 located on the protrusion is formed as a display electrode space is aligned with the chrome pattern and exposed.

Thereafter, the positive resist is developed in an alkali developing solution at room temperature for 1 minute.

As a result, as shown in FIG. 5, the resist pattern of the first overcoat film 21 of the cylindrical protrusion is patterned and formed as the display electrode space, so that the transparent conductive film is formed by etching. As a result, the protrusion step of the first overcoat film 21 of the cylindrical protrusion can be formed as a patterning spacer.

Therefore, by using the overcoat film 2 having photosensitivity, the overcoat film of the color filter 4 is excellent in flatness and, at the same time, as the patterning spacer, the adhesion strength withstanding the frictional force in the rubbing process at the time of cell assembling is provided. It becomes possible to manufacture the color filter substrate having the patterning spacer.

Then, using the substrate on which the above-mentioned color filter is formed, an alignment film is printed and then a rubbing alignment treatment is performed, and cell assembly is performed without a spacer spraying process for cell gap formation, resulting in no cell gap unevenness. It has become possible to manufacture uniform color liquid crystal display devices.

In the above description, the second overcoat film 2
Although the shape of the protrusion formed in 2 is a cylindrical shape, an elliptical shape or a polygonal shape can be applied as the patterning spacer.

[0081]

As is apparent from the above description, according to the present invention, a gap maintaining agent for an STN type ferroelectric liquid crystal display device or an antiferroelectric type liquid crystal display device which requires a cell gap precision. As a patterning spacer having adhesion strength, the color filter has excellent flatness,
Moreover, it is possible to obtain a color liquid crystal display device using a substrate having a strong extraction electrode on glass and provided with a color filter.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure and a manufacturing method of a liquid crystal display device in an example of the present invention.

FIG. 2 is a cross-sectional view showing a structure and a manufacturing method of a liquid crystal display device in an example of the present invention.

FIG. 3 is a cross-sectional view showing a structure and a manufacturing method of a liquid crystal display device in an example of the present invention.

FIG. 4 is a cross-sectional view showing a structure and a manufacturing method of a liquid crystal display device in an example of the present invention.

FIG. 5 is a perspective view showing a patterning spacer, showing a structure and a manufacturing method of a liquid crystal display device in an example of the present invention.

FIG. 6 is a graph showing the relationship between the exposure amount and the residual film ratio of a negative overcoat film for explaining the method of manufacturing a liquid crystal display device in an example of the present invention.

FIG. 7 is a cross-sectional view showing a method of manufacturing a liquid crystal display device in a conventional example.

FIG. 8 is a cross-sectional view showing a method of manufacturing a liquid crystal display device in a conventional example.

FIG. 9 is a cross-sectional view showing a method of manufacturing a liquid crystal display device in a conventional example.

FIG. 10 is a cross-sectional view showing a method of manufacturing a liquid crystal display device in a conventional example.

FIG. 11 is a plan view showing a method of manufacturing a liquid crystal display device in a conventional example.

FIG. 12 is a cross-sectional view showing a state in which liquid crystal display devices are overlapped with each other by a patterning spacer method.

[Explanation of symbols]

 1a First photomask 1b Second photomask 2 Overcoat film 21 First overcoat film 22 Second overcoat film 3 Black matrix 4 Color filter 5 Substrate 7 Transparent conductive film 71 Extraction electrode 72 Display electrode 8 Alignment film

Claims (3)

[Claims] 1. A substrate provided with a color filter and a black matrix, an overcoat film provided on the color filter, and a transparent conductive film provided on the overcoat film, wherein the overcoat film has a projection, and the projection is provided. A liquid crystal display device comprising a patterning spacer that functions as a cell gap maintaining agent. 2. A substrate provided with a color filter and a black matrix, an overcoat film provided on the color filter, and a transparent conductive film provided on the overcoat film, and the overcoat film has projections, and the projections are provided. A liquid crystal display device comprising a patterning spacer having a cylindrical shape, an elliptical shape, or a polygonal shape that acts as a cell gap maintaining agent. 3. A step of forming a black matrix on a substrate, a step of forming a color filter, an overcoat film having photosensitivity is formed on the entire surface, and the overcoat film is formed by using two photomasks. A step of exposing at a stage, a step of developing to form protrusions on the photosensitive overcoat film to simultaneously form an overcoat film and a patterning spacer in the color filter region, and a step of patterning the transparent conductive film A method for manufacturing a liquid crystal display device, comprising: