JPH112818A - Manufacture of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture of the liquid crystal display device which has good display uniformity and high contrast characteristics without using a high-precision photomask and an aligner and increasing the man-hour. SOLUTION: For this manufacture, a transparent substrate 1 which has a light shield layer 2 is coated with positive resist 4 having black spherical resin 5 dispersed and the top and reverse surfaces of the substrate 1 are both exposed at a time and then developed to leave only the positive resist 4 below the black spherical resin 5, which is adhered onto only the light shield layer 2 with the positive resist 4. By this method, the uniformity of liquid crystal layer thickness is improved to make the display uniformity better and no gap is scattered in the display surface, so the contrast characteristics can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for manufacturing a liquid crystal display device in which a method for forming a gap material is improved.

[0002]

2. Description of the Related Art In a liquid crystal display device, two transparent substrates having electrodes for driving a liquid crystal layer are opposed to each other at a predetermined interval, liquid crystal is injected between the transparent substrates, and the periphery thereof is sealed with a sealing material. It has a sealed structure. In order to keep the liquid crystal layer between the transparent substrates at a predetermined interval, a “spherical resin” called a “gap material (gap holding material)” is generally scattered in the display surface.

However, in the conventional liquid crystal display device, since a gap material is also formed on the liquid crystal display surface, the transmission and dispersion of light by the gap material lowers the contrast of the liquid crystal display device and deteriorates the display characteristics. On the other hand, if there are irregularities on the transparent substrate, even if the gap material is scattered, the uniformity of the gap is reduced due to the irregularities on the substrate, and display unevenness or the like occurs, thereby deteriorating the display characteristics. Furthermore, by moving the gap material, the alignment film is damaged, or the liquid crystal orientation is disturbed, or the gap material is unevenly scattered,
Display flaws and display unevenness occur to lower display characteristics.

In order to improve the above-described “deterioration in display characteristics”, as described in the following first to sixth conventional methods,
Various devices have been used in the past.

(First Conventional Method) Japanese Patent Application Laid-Open No. Sho 62-239126 discloses a technique for improving the display quality by removing the influence of light scattering, light transmission and light absorption of a gap material itself on a display image.
A method of manufacturing a liquid crystal display device in which a gap material is disposed only in an upper portion of a light shielding layer is disclosed (hereinafter, referred to as a “first conventional method”). This first conventional method will be described with reference to FIG. (Note that FIG. 3 is a view for explaining the first conventional method, and is a sectional view in the order of steps including steps (A) to (D) for forming a gap material.)

As shown in FIGS. 3A to 3D, the first conventional method includes: a step of forming a light-shielding layer 2 and a colored layer 7 on a transparent substrate 1 [→ FIG. )], A step of applying a positive resist 4 in which a gap material 5a is dispersed [→ FIG. 3 (B)], a light shielding of a desired pattern so that the positive resist 4 remains only on the upper part of the light shielding layer 2. Step of exposing through the photomask 11 on which the layer 12 is formed [→ FIG. 3 (C)]. ・ Resist development is performed to remove the gap material 5a in the pixel portion. The gap material 5a is fixed by a positive resist 4.

However, in the first conventional method, the positive resist 4 remains on the gap material 5a (FIG. 3).
(D)), the distance between the liquid crystal layers is hardly controlled by the thickness of the residual positive resist 4, and the gap uniformity is poor. Further, since it is necessary to leave the positive resist 4 only on the light-shielding layer 2, a high-precision photomask 11 and an exposure facility capable of high-precision overlapping are required, so that it is difficult to form the gap material 5a. In addition, there is a problem that the manufacturing cost of the liquid crystal display device is increased.

(Second conventional method) Japanese Patent Application Laid-Open No. 2-157728 discloses that a positive resist is left only on a light-shielding layer by exposing from the back surface of a substrate, and then a gap material is sprayed, and light irradiation or heat treatment is performed. A method for fixing the gap material is disclosed (hereinafter, referred to as “second conventional method”). This second conventional method will be described with reference to FIG. (Note that FIG. 4 is a view for explaining the second conventional method, and is a sectional view in the order of steps including steps (A) to (E) for forming a gap material.)

The second conventional method is, as shown in FIGS. 4A to 4E, a step of applying a positive resist 4 to a transparent substrate 1 having a light shielding layer 2 [→ FIG. A step of exposing from the back surface of the transparent substrate 1 [→ FIG. 4 (B)], a step of developing and leaving the positive resist 4 only on the light-shielding layer 2 [→ FIG. 4 (C)], a gap material Step of spraying 5a [→ FIG. 4 (D)], Step of fixing gap material 5a with positive resist 4 by light irradiation or heat treatment, and then removing unfixed gap material 5a by washing etc. [→ FIG. (E)].

The second conventional method is different from the first conventional method in that the exposure is performed from the back surface of the transparent substrate 1, so that a photomask 11 similar to the first conventional method [see FIG. ] Is unnecessary, and there is a good advantage in the exposure equipment without the superposition mechanism. In addition, the formed gap material 5
a has the advantage that the positive resist 4 does not remain on the surface. However, in the second conventional method, as shown in FIG. 4E, the positive resist 4 remains under the gap material 5a, so that the gap uniformity is deteriorated and the display characteristics are deteriorated. Further, the application of the positive resist 4 and the gap material 5
Since the spraying of a is performed separately, there is a disadvantage that the number of steps increases. In addition, since the gap material 5a is later bonded to the positive resist 4 by light irradiation or heat treatment, there is a new problem that the adhesiveness of the gap material 5a is poor.

(Third conventional method) JP-A-4-110827 discloses that a gap material coated with a photosensitive resin is sprayed, exposed from the back surface of the substrate, and the gap material is selectively formed only on the light shielding layer. A forming method is disclosed (hereinafter, referred to as “third conventional method”). This third conventional method will be described with reference to FIG. (Note that FIG. 5 is a view for explaining the third conventional method, and is a sectional view in the order of steps including steps (A) to (D) for forming a gap material.)

The third conventional method comprises, as shown in FIGS. 5A to 5D, a step of forming a light shielding layer 2, a protective film 13 and a transparent electrode 6 on a transparent substrate 1 [→ FIG. 5 (A)], a step of spraying the gap material 5b coated with the photosensitive resin [→ FIG. 5 (B)], a step of exposing from the back surface of the transparent substrate 1 [→ FIG. 5 (C)], A step of performing development, selectively removing the gap material 5b on the transparent electrode 6, and forming the gap material 5b only on the light-shielding layer 2 [→ FIG. 5D].

In the third conventional method, as in the second conventional method, a photomask and an overlay exposure facility are not required, the advantage is that the number of steps is not increased, and the manufacturing cost does not increase. . However, when the photosensitive resin is used as the gap material 5
b, it is difficult to cover the gap material uniformly, and since the gap material 5b is covered with the photosensitive resin, a uniform gap cannot be obtained, and further, the gap material is weakly fixed. ing.

(Fourth conventional method) Japanese Patent Application Laid-Open No. 5-307181 discloses a method of forming a gap material by exposing from the back surface (hereinafter referred to as a "fourth conventional method"). This fourth conventional method will be described with reference to FIG.
(Note that FIG. 6 is a diagram illustrating a fourth conventional method.
FIG. 5 is a sectional view in the order of steps including steps (A) to (C) of forming a gap material. )

As shown in FIGS. 6A to 6C, the fourth conventional method is as follows: a gap material 5a is formed on a transparent substrate 1 on which a light shielding layer 2, a transparent electrode 6, and an alignment film 3 are formed. Step of applying dispersed positive resist 4 [→ FIG. 6 (A)], Step of exposing from the back surface of transparent substrate 1 using light-shielding layer 2 as a mask [→ FIG. 6 (B)], A step of removing a portion of the positive resist 4 and forming a gap material 5a only on the light-shielding layer 2 [→ FIG. 6 (C)].

The fourth conventional method has an advantage that a high-precision photomask and an exposure device are not required and that the number of steps is not increased, and the cost of the liquid crystal display device can be suppressed. Since the upper positive resist 4 cannot be removed, there is a disadvantage that gap uniformity is poor.

(Fifth conventional method) JP-A-63-98635 discloses that a positive resist in which a gap material containing an ultraviolet absorber is dispersed is exposed from the surface to remove the positive resist on the gap material. In addition, a method of fixing the gap material with the remaining positive resist is disclosed.
(Hereinafter referred to as “fifth conventional method”). This fifth conventional method will be described with reference to FIG. (FIG. 7 is a view for explaining the fifth conventional method, and shows a step (A) of forming a gap material.
FIG. 6 is a sectional view in the order of steps consisting of (D) to (D). )

This fifth conventional method comprises, as shown in FIGS. 7A to 7D, a step of forming a transparent electrode 6 on a transparent substrate 1 [→ FIG.
(A)], a step of mixing a gap material 5c containing an ultraviolet absorber into the positive resist 4 and applying the mixture to the transparent substrate 1 [→ FIG.
(B)], a step of exposing the positive resist 4 from the surface [→ FIG.
(C)], developing, leaving the positive resist 4 under the gap material 5c, removing an excess of the positive resist 4, and further performing baking to form the gap material 5c with the positive resist 4 remaining under the gap material 5c. Is fixed (see FIG. 7D).

According to the fifth conventional method, the gap material 5
Since the positive resist 4 on c is removed, there is an advantage that the gap uniformity of the display device can be improved. However, the problem that the display characteristics deteriorate because the gap material 5c remains in the display surface has not been solved yet.

(Sixth conventional method) Japanese Patent Application Laid-Open No. 4-188109 discloses that a gap material-mixed positive resist is applied on an alignment film that has been subjected to an alignment treatment, or a gap material is applied after the positive resist is applied. A method of spraying, forming a thick positive resist film around the gap material by the surface tension of the positive resist, exposing from the surface, and fixing the gap material with the thick portion of the positive resist is disclosed (hereinafter referred to as “No. 6). Conventional method ”). This sixth conventional method will be described with reference to FIG. (Note that FIG. 8 is a view for explaining the sixth conventional method, and is a cross-sectional view in the order of steps including steps (A) to (D) for forming a gap material.)

The sixth conventional method comprises, as shown in FIGS. 8A to 8D, a process of forming an alignment film 3 on a transparent substrate 1 having a light-shielding layer 2 and performing an alignment process [→ FIG. 8 (A)]. Positive resist 4 mixed with gap material 5a is applied, or after applying positive resist 4, gap material 5a is applied.
And forming a thick positive resist film around the gap material 5a by the surface tension of the positive resist 4 [→
FIG. 8 (B)], a step of exposing from the surface of the substrate 1 [→ FIG. 8 (C)], and a step of developing and removing the gap material 5a while leaving the thick positive resist 4 around the gap material 5a. The step of fixing [→ FIG. 8 (D)].

The sixth conventional method has almost the same advantages and disadvantages as the fifth conventional method. The positive resist 8 on the gap material 5a can be removed, and the uniformity of the gap of the display device is good. On the other hand, since the gap material remains in the display surface, there is a problem that the display characteristics are deteriorated.

[0023]

The conventional methods 1 to 6 have the above-described disadvantages and problems, respectively. In particular, in the method of exposing from the back surface of the transparent substrate as in the second, third, and fourth conventional methods, the gap uniformity is poor because the positive resist remains on or under the gap material. Become. That is, there is a problem that the thickness of the liquid crystal layer becomes uneven, display unevenness or the like occurs, and display characteristics deteriorate.

On the other hand, in the method of exposing from the surface of the transparent substrate as in the first, fifth, and sixth conventional methods, a gap material remains on the display surface, and light is emitted by the gap material remaining on the display surface. This has the drawback of causing transmission and scattering of light, hindering the switching of light by the liquid crystal, thereby lowering contrast characteristics and deteriorating display characteristics.

The present invention has been made in view of the above-mentioned problems and disadvantages of a conventional liquid crystal display device, and has as its object to firstly achieve high display uniformity and high contrast characteristics. Secondly, a method capable of easily manufacturing a liquid crystal display device having high display uniformity and contrast characteristics, and thus suppressing an increase in the manufacturing price. To provide.

[0026]

According to the present invention, a substrate having a light-shielding layer is coated with a positive resist mixed with a black spherical resin (gap material), and is exposed from both the front and rear surfaces of the substrate. Is bonded and fixed only above the light-shielding layer with a residual positive resist thereunder, thereby providing the above-mentioned method of manufacturing a liquid crystal display device.

That is, the present invention provides a method for manufacturing a liquid crystal display device, comprising the steps of (1) applying a positive resist in which a black spherical resin is dispersed on a substrate having a light-shielding layer, and (2) applying the positive resist. A step of exposing from both sides of the substrate, and (3) developing the positive resist, removing the positive resist in the exposed portion, and forming the black spherical resin on the substrate with the unexposed positive resist under the black spherical resin. And a method of manufacturing a liquid crystal display device, comprising the steps of: (a) claim 1;

According to the present invention, the substrate having the light shielding layer is a color filter substrate having a light shielding layer or a thin film transistor substrate having a metal wiring.
A positive resist in which a black spherical resin is dispersed is applied to one of the filter substrate and the thin film transistor substrate.

[0029]

According to the present invention, as described above, a black spherical resin (gap material) is formed only on the light-shielding layer, and the black spherical resin is bonded and fixed with a positive resist.
Since no positive resist remains on the black spherical resin,
A liquid crystal display device having high contrast characteristics, uniform thickness of a liquid crystal layer, no display unevenness, and excellent display characteristics can be provided. In addition, since the present invention does not require a high-precision photomask or an exposure apparatus and does not increase the number of steps, it can be easily manufactured and can suppress an increase in the price of a liquid crystal display device.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIG. (Note that FIG. 1
It is a figure explaining an example of the manufacturing method concerning the present invention, and is a process order sectional view consisting of steps (A)-(D) which form a black spherical resin (gap material). )

As shown in FIGS. 1A to 1D, the method of forming a gap material according to the present invention comprises the steps of:
This alignment film 3 is subjected to an alignment treatment using a rubbing device [→ FIG. 1 (A)]. ・ Positive resist 4 mixed with black spherical resin 5 is applied to the substrate [→ FIG. 1 (B)]. Exposure is performed from both the front surface and the rear surface of the transparent substrate 1 (see FIG. 1 (C)). The development is performed to remove the exposed portion of the positive resist 4 and to form the black spherical resin 5 and the substrate into the spherical shape. Bonded by unexposed positive resist 4 remaining under resin
[→ Fig. 1 (D)].

Next, a method for manufacturing a liquid crystal display device according to the present invention will be described with reference to FIGS.
(Note that FIG. 2 is a schematic cross-sectional view illustrating an example of the liquid crystal display device manufactured according to the present invention.)

First, the color filter substrate Z shown in FIG. 2 is formed according to the manufacturing method shown in FIGS. 1A to 1D. (The color filter substrate Z shown in FIG. 2 and the transparent substrate 1 shown in FIG. 1 are the same as the color filter substrate Z in which the colored layer 7 and the transparent electrode 6 are formed before the alignment film 3 is formed. And the subsequent manufacturing steps are the same as in FIGS. 1 (A) to 1 (D).)

On the other hand, a counter substrate (thin film transistor substrate Y)
The wiring electrode 8, the insulating film 9,
A thin film transistor substrate Y having a transparent electrode 6a is formed, an alignment film 3a is formed thereon, and rubbing is performed (see FIG. 2). The thin film transistor substrate Y and the color filter substrate Z are overlapped, a liquid crystal 10 is injected between the substrates, and the periphery thereof is sealed with a sealing material to manufacture a liquid crystal display device.

In the liquid crystal display device manufactured as described above, since the black spherical resin 5 (gap material) is formed only on the light shielding layer 2, the liquid crystal display device is different from the conventional method in which the gap material exists in the display surface. Thus, it has high contrast characteristics. In addition, since the black spherical resin 5 is bonded and fixed by the underlying positive resist 4, "gap unevenness of the liquid crystal layer due to the movement of the black spherical resin 5" does not occur, and the display characteristics are degraded. Does not occur. Furthermore, since the positive resist 4 does not remain on the black spherical resin 5,
The gap becomes uniform, so that the gap can be controlled only by the diameter of the black spherical resin 5, and a liquid crystal layer having an optimum gap can be easily formed.

[0036]

Next, an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2 described above. However, the present invention is not limited to the following embodiment, and the gist of the present invention is described. Can be appropriately changed within the range described above.

In this embodiment, as shown in FIG. 2, a light-shielding layer 2 and a colored layer 7 were formed on a transparent substrate 1, and a transparent electrode 6 as a common electrode was formed on the surface. Specifically, a substrate having a thickness of 0.7 mm is used as the transparent substrate 1, a light-shielding layer 2 having a thickness of 1.5 μm and a coloring layer 7 having a thickness of 1 μm are formed on the transparent substrate 1, and the surface thereof is formed with a common electrode. It was covered with a certain transparent electrode 6.

A black spherical resin 5 (gap material) was formed on the transparent substrate 1 having the light-shielding layer 2 thus formed by the method shown in FIGS. 1A to 1D described above.

First, on a transparent substrate 1 having a light shielding layer 2,
A polyimide film having a thickness of 0.1 μm was formed as the alignment film 3, and the alignment film 3 was subjected to a rubbing treatment (see FIG. 1A).
Next, "OFPR" (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used as the positive resist 4, and "Black Micropar" (trade name, manufactured by Sekisui Fine Chemical Co., Ltd.) having a diameter of 5 .mu.m was used as the black spherical resin 5. Was mixed with the transparent substrate 1 using a spin coater [→ see FIG. 1 (B)]. At this time, the thickness of the positive resist was set to 2 μm in a state of being dried after the application.

Subsequently, as shown in FIG. 1C, exposure and development are performed from both the front and back surfaces of the substrate, and development is performed.
As shown in (D), the exposed portion of the positive resist 4 is removed, and the black spherical resin 5 is adhered and fixed to the substrate by the unexposed positive resist 4 remaining thereunder. Z (see FIG. 2) was produced.

On the other hand, as a counter substrate, a thin film transistor having a transparent electrode 6a, a wiring electrode 8, and an insulating film 9 is formed on a transparent substrate 1a, an alignment film 3a is formed on the surface thereof, and a rubbing process is performed to perform a rubbing process. (See Fig. 2)
Was prepared. Then, as shown in FIG. 2, the thin film transistor substrate Y is overlaid on the color filter substrate Z, a liquid crystal 10 is injected between the substrates, and the periphery thereof is sealed with a sealing material (not shown). A liquid crystal display device was manufactured.

The liquid crystal display device thus manufactured is
Since the black spherical resin 5 (gap material) was formed only above the light shielding layer 2, the contrast characteristic was 1: 300 or more. In contrast, in a conventional liquid crystal display device in which a gap material exists in the display surface, the contrast characteristic is limited to about 1: 100. Further, since the black spherical resin 5 (gap material) was fixed with the positive resist 4 thereunder, no movement of the black spherical resin 5 was recognized even when a vibration test was performed. As a result, the gap characteristics of the liquid crystal layer did not occur, and the display characteristics were good.

Further, the positive resist 4 is made of a black spherical resin 5
Since the gap does not remain on the gap, the gap can be made uniform, and the gap itself can be controlled only by the diameter of the black spherical resin 5, so that a liquid crystal layer having an optimum gap can be easily formed. The reason is that the total value of the thickness of the light shielding layer 2 and the thickness of the black spherical resin 5 (gap material) becomes the thickness of the liquid crystal layer as it is, so that the gap can be formed as designed. In fact, even in the prototype stage, a liquid crystal layer having a desired gap could be easily formed.

The gap of the liquid crystal display device manufactured in this embodiment is 6.5 ± 0.3 μm, and the uniformity of the gap is ± 5%.
The following could be controlled. In this regard, it is found that the gap uniformity can be remarkably improved according to the method of the present invention, as compared with the fact that the gap uniformity according to the conventional method is about ± 20%.

[0045]

As described in detail above, the present invention applies a positive resist mixed with a black spherical resin (gap material) to a substrate having a light-shielding layer, and exposes the substrate from both the front and back surfaces of the substrate. The spherical resin is characterized by being adhered and fixed only above the light-shielding layer with the remaining positive resist thereunder, thereby eliminating the movement of the black spherical resin, and the surface of the spherical resin (top and bottom) Thus, a positive resist can be prevented from remaining in the liquid crystal display device, and thus a liquid crystal display device having high display uniformity can be provided.

Further, according to the present invention, a black spherical resin (gap material) is located only above the light shielding layer and is not scattered in the liquid crystal display surface, so that a liquid crystal display device having high contrast characteristics is provided. It is possible to further eliminate the need for a photomask or overlay exposure equipment and the like, and since there is no increase in the number of steps, the display uniformity described above is high.
Moreover, there is an effect that a liquid crystal display device having high contrast characteristics can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a view for explaining an example of a production method according to the present invention, and shows steps (A) to (A) for forming a black spherical resin (gap material).
It is a process order sectional view consisting of (D).

FIG. 2 is a schematic sectional view showing an example of a liquid crystal display device manufactured according to the present invention.

FIG. 3 is a view for explaining the first conventional method, and is a cross-sectional view in the order of steps including steps (A) to (D) for forming a gap material.

FIG. 4 is a view for explaining a second conventional method and is a sectional view in the order of steps including steps (A) to (E) for forming a gap material.

FIG. 5 is a view for explaining a third conventional method, and is a sectional view in the order of steps including steps (A) to (D) for forming a gap material.

FIG. 6 is a view for explaining a fourth conventional method, and is a sectional view in the order of steps including steps (A) to (C) for forming a gap material.

FIG. 7 is a view for explaining a fifth conventional method, and is a sectional view in the order of steps including steps (A) to (D) for forming a gap material.

FIG. 8 is a view for explaining a sixth conventional method, and is a sectional view in the order of steps including steps (A) to (D) for forming a gap material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Transparent substrate 2 Light shielding layer 3, 3a Alignment film 4 Positive resist 5 Black spherical resin (gap material) 5a Gap material 5b Gap material coated with photosensitive resin 5c Gap material containing ultraviolet absorber 6,6a Transparent electrode Reference Signs List 7 colored layer 8 wiring electrode 9 insulating film 10 liquid crystal 11 photomask 12 light shielding layer (photomask) 13 protective film Y thin film transistor substrate Z color filter substrate

Claims (2)

[Claims] 1. A method of manufacturing a liquid crystal display device comprising the steps of:
On a substrate having a light-shielding layer, a step of applying a positive resist in which a black spherical resin is dispersed, (2) a step of exposing from both sides of the substrate coated with the positive resist, and (3) a step of developing and exposing the positive resist Removing the positive resist from the exposed portion, and adhering the black spherical resin to the substrate with the unexposed positive resist under the black spherical resin. 2. The method according to claim 1, wherein the substrate having the light shielding layer is a color filter substrate having the light shielding layer or a thin film transistor substrate having metal wiring.