JP2000214470A - Dry film resist and production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make formable a uniform cell thickness and to decrease the number of processes by using a dry film resist having spacer beads dispersed on a base film as a supporting body to regulate the cell thickness and a photosensitive resin layer formed on the base film. SOLUTION: This dry film resist 10 consists of a base film 11, transparent plastic spacer beads 3 dispersed on the base film 11, and a cushion layer 12, an oxygen cutting film 13, a transparent photosensitive resin layer 14 and a cover film 15 successively laminated on the base film 11. By mixing the beads 3 in the dry film resist 10, the film resist 10 shows good following-up property for a rugged pattern when pressed and adhered, and the thickness of the cushion layer 12 can be made thin compared with a conventional structure. Polymer walls of a liquid crystal display device are formed by heat sealing this dry film resist 10 on a substrate by using a laminator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist used for manufacturing a liquid crystal display device, and a method for manufacturing a liquid crystal display device. More particularly, the present invention relates to a method for manufacturing a liquid crystal display device. The present invention relates to a method for manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally formed dry film resist 10
FIG. 6 shows the structure. Conventional dry film resist 1
Reference numeral 0 denotes a cushion layer 12 (15 μm) made of a thermoplastic resin on a base film 11 made of polyethylene terephthalate having a thickness of 75 μm as a support to improve the conformability of the film during thermocompression bonding (lamination).
m), an oxygen barrier film 13 (2 μm) for preventing the resist from bonding with oxygen and becoming unpolymerizable, a photosensitive resin layer 14 (2 μm) serving as a resist, and a cover film 15 made of polypropylene which is a protective film for the resist. (1
5 μm) are sequentially laminated.

The resist is peeled off the cover film 15 of the dry film resist 10, and the photosensitive resin layer 14 is bonded to the substrate by pressing and heating using a laminator. It is formed on the substrate by peeling off at the interface with the layer 12 and removing the support.

Hereinafter, a conventional liquid crystal display device and a method for manufacturing the same will be described.

Conventionally, as a display device using the electro-optic effect, a TN (twisted nematic) type using a nematic liquid crystal or a STN (super twisted nematic) has been used.
Type liquid crystal display devices are used. Techniques for increasing the viewing angle of these liquid crystal display devices have been energetically developed.

Japanese Patent Laid-Open No. 6-301 discloses one of the techniques for increasing the viewing angle of a TN type liquid crystal display device that has been proposed so far.
No. 015 and JP-A-7-120728 disclose a liquid crystal display device having axisymmetrically aligned liquid crystal molecules in a liquid crystal region divided by polymer walls, a so-called ASM.
(Axially Symmetrically al
A liquid crystal display device of an ignited Microcell mode is disclosed. A liquid crystal region substantially surrounded by polymer walls is typically formed for each pixel. ASM
In the mode liquid crystal display device, the liquid crystal molecules are axially symmetrically aligned.
The change in contrast is small, that is, it has a wide viewing angle characteristic.

[0007] The ASM mode liquid crystal display device disclosed in the above publication is manufactured by subjecting a mixture of a polymerizable material and a liquid crystal material to polymerization induced phase separation.

FIG. 9 shows a cross-sectional structure of a conventional color filter 20. A black matrix (BM) 331 on the glass substrate 308 for shielding the gap between the colored patterns from light
And a red, green, and blue (R, G, and B) colored resin layer 330 corresponding to each picture element. On top of these, ITO
In order to improve the smoothness in order to prevent disconnection during film formation, or to etch the BM film 3 at the time of ITO etching.
In order to protect the resin surface from corroding the resin layer 31 and the colored resin layer 330, an overcoat (OC) layer 3 made of an acrylic resin or an epoxy resin and having a thickness of about 0.5 to 2.0 μm.
32 are formed. Further, an indium tin oxide (ITO) film of the transparent signal electrode 333 is formed thereon. The BM film 331 generally has a thickness of about 100 to 1
It is made of a 50-μm metal chromium film. Recently, however, a photoresist type material in which fine particles of carbon, such as carbon, are dispersed in an acrylic photosensitive resin is also used. For the colored resin layer 330, a resin material colored with a dye or a pigment is used.
μm is common.

As a method of forming a color filter, a method of patterning a photosensitive colored resin layer formed on a substrate by using a photolithography technique is used. For example, using a photosensitive resin material of each color of red (R), green (G), and blue (B), formation, exposure,
By performing each development (total of three times), R · G
B color filters can be formed. The method for forming the photosensitive colored resin layer includes a method in which a liquid photosensitive colored resin material (diluted with a solvent) is applied to a substrate by spin coating or the like, or a method in which the photosensitive colored resin material formed into a dry film is used. There is a transfer method.

[0010] Next, referring to FIG.
A method for manufacturing a mode liquid crystal display device will be described.

First, a substrate having a color filter and electrodes formed on one surface of a glass substrate 308 is prepared (step (a)). The electrodes and the color filters formed on the upper surface of the glass substrate 308 are not shown for simplicity.

Next, on the surface of the glass substrate 308 on which the electrodes and the color filters are formed, polymer walls 317 for aligning the liquid crystal molecules in an axially symmetric manner are formed, for example, in a lattice shape (step (b)). . That is, after spin-coating the photosensitive resin material, exposure and development are performed through a photomask having a predetermined pattern, thereby forming the lattice-shaped polymer wall 317. The photosensitive resin material may be a negative type or a positive type. In addition, the number of steps for forming a resist film separately increases, but the polymer wall can be formed using a resin material having no photosensitivity.

On the top of a part of the obtained polymer wall 317,
The columnar projections 320 are discretely formed by patterning (step (c)). The columnar projections 320 are also formed by applying, exposing, and developing a photosensitive resin material.

The surface of the glass substrate 308 on which the polymer walls 317 and the columnar projections 320 are formed is covered with a vertical alignment agent 321 such as polyimide (step (d)). On the other hand, the surface of the opposing glass substrate 302 (step (e)) on which the electrodes are formed is also covered with the vertical alignment agent 321 (step (f)).

The two substrates obtained are bonded together with the surface on which the electrodes are formed facing inward to form a liquid crystal cell (step (g)). The distance (cell gap; thickness of the liquid crystal layer) between the two substrates is defined by the sum of the heights of the polymer wall 317 and the columnar projection 320.

A liquid crystal material 316 is injected into the gap between the obtained liquid crystal cells by a vacuum injection method or the like (step (h)). Finally, for example, by applying a voltage between a pair of electrodes arranged opposite to each other, the liquid crystal molecules in the liquid crystal region 315 are axially symmetrically controlled (step (i)). The liquid crystal molecules in the liquid crystal region divided by the polymer wall 317 are shown in FIG.
Axisymmetrically oriented around the axis shown by the broken line (perpendicular to both substrates).

By using the color filters formed as described above, an ASM mode liquid crystal display device having a wide viewing angle characteristic can be obtained.

However, when the above-described ASM mode is applied to a liquid crystal display device, there are the following problems.

Since columnar projections for defining the cell thickness are formed by applying a photosensitive resin material to a substrate and then patterning the same by a photolithography method, the columnar projections are formed when the photosensitive resin material is applied. The film thickness variation causes a large cause of display unevenness. Further, in order to increase the definition of the liquid crystal display device and improve the display brightness, it is desirable that the width of the polymer wall which makes the liquid crystal molecules be symmetrically aligned in the ASM mode be as narrow as possible and as low as possible. However, in this case, the height of the columnar projection for relatively defining the cell thickness must be increased, and therefore, the influence of the film thickness variation at the time of forming the columnar projection becomes larger. Further, it is difficult to form the columnar projection so that the bottom does not protrude from the polymer wall.

In addition, by defining the cell thickness by spacer beads instead of the cell thickness by the columnar projection using the photosensitive resin material as described above, the cell thickness uniformity can be greatly improved. . That is, mix the spacer beads with the liquid resist, apply it to the substrate,
The cell thickness is defined by performing exposure and development. However, this technique has a problem as shown in FIG.

That is, the beads 3 may float from the substrate 1 in the cured liquid resist film 21 and may have a cell thickness variation of up to the cured liquid resist film thickness 22 at the maximum. In order to avoid this, it is necessary to add a step such as pressing to keep the height of the beads constant before baking the resist.

A method of spraying beads in the middle of the process is also common. However, in this case, there is a problem of contamination of another process by beads, and there is a concern that the production yield may be reduced.

[0023]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the cell thickness of a liquid crystal display device can be formed to be much more uniform than that of a conventional structure. It is an object of the present invention to provide a liquid crystal display device in which the number of steps is reduced as compared with the method and a method for manufacturing the same.

[0024]

According to the present invention, there is provided a base film serving as a support, spacer beads for defining a cell thickness spread on the base film, and a photosensitive film formed on the base film. It is a dry film resist having a resin layer. Thereby, the above object is achieved.

In a preferred embodiment, the spacer
The beads are true spheres.

In a preferred embodiment, the dry film resist further has a cover film formed on the photosensitive resin layer, wherein the diameter of the spacer beads is equal to the base film and the cover film. Is less than or equal to the distance between

[0027] The present invention also includes a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates, wherein the liquid crystal layer is formed on a color filter formed on at least one of the pair of substrates. It has a plurality of liquid crystal regions divided by a certain polymer wall, and liquid crystal molecules in the plurality of liquid crystal regions are axially symmetrically aligned around an axis perpendicular to the pair of substrates, and the polymer wall is A transparent resin layer having a forward tapered inclined portion with respect to the substrate, wherein spacer beads for defining the cell thickness of the pair of substrates are fixed by the polymer wall. A base film serving as a support, a spacer bead for defining a cell thickness dispersed on the base film, and a substrate formed on the base film on at least one of the pair of substrates. The photosensitive resin layer To a dry film resist sticking Keru step, and a step, to create the polymer wall is patterned by photolithography to the dry film resist, a manufacturing method.

[0028]

Embodiments of the present invention will be described below.

(Embodiment 1) FIGS. 1 (a) and 1 (b)
It is the figure which represented typically the structure of one Embodiment of the liquid crystal display device of this invention, Comprising: (a) and (b) are sectional drawing and top views, respectively. The liquid crystal display device 30 includes a glass substrate 1 and a black matrix 6 formed on the glass substrate 1.
And red, green, and blue colored resin layers 7 (that is, color filters), an overcoat layer 5 formed on the color filter surface, an ITO signal electrode 4 formed on the overcoat layer 5, and liquid crystal molecules. Has a polymer wall 2 for axially symmetric orientation. The overcoat layer 5 covers a portion where a step is formed on the surface of the color filter immediately above the black matrix 6 and functions as a protective film on the surface of the color filter. The ITO signal electrode 4 is formed by forming an ITO film on the overcoat layer 5 by sputtering and then patterning the ITO film. The polymer wall 2 is formed by using the dry film resist of the present invention thermocompressed on the substrate 1 using a laminator.

FIG. 3 shows the structure of the dry film resist 10 of the present invention. FIG. 3A shows the case where the diameter of the spacer beads is equal to the sum of the thicknesses of the photosensitive resin layer, the oxygen blocking layer and the cushion layer, and FIG. , The case where it is smaller than the sum of the thicknesses of the oxygen barrier layer and the cushion layer. The dry film resist 10 is composed of a base film 11 having a thickness of 75 μm, transparent plastic spacer beads 3 having a diameter of 5.5 μm dispersed on the base film 11, and a cushion layer 12 ( 5μ
m), oxygen barrier film 13 (2 μm), transparent photosensitive resin layer 14 (1 μm) and cover film 15 (20 μm)
Having. Spacer beads 3 can be of any shape, preferably spherical. By mixing the beads 3 in the dry film resist 10, the film resist 1
The conformability to unevenness at the time of zero pressure bonding is improved, and the thickness of the cushion layer 12 can be reduced as compared with the conventional structure. Photosensitive resin layer 14
Forms the polymer wall 2 as described below with reference to FIG.

In this embodiment, the photosensitive resin layer 14
(That is, a polymer wall material) was a negative type. When a positive resist is used as a polymer wall material, the resist immediately below the spacer beads 3 may not be sufficiently irradiated in the exposure step. Therefore, the spacer beads 3 may be left in the region of the opening where the spacer beads 3 are not desired to remain.

The liquid crystal display 30 further includes a polymer wall 2
And a vertical alignment layer (not shown) formed by spin-coating polyimide resin JALS-204 (manufactured by Japan Synthetic Rubber) on the glass substrate 1 on which the spacer beads 3 are formed.

The polymer wall 2 has a forward tapered inclined portion forming an inclined angle (taper angle) θ with respect to the substrate surface. By setting the inclination angle θ of the polymer wall 2 to 5 degrees or more and 45 degrees or less, a stable axially symmetric alignment state can be realized. If the inclination angle θ of the polymer wall 2 is smaller than 5 degrees, the wall effect of stably controlling the liquid crystal molecules in the axially symmetric alignment is lost. Therefore, the inclination angle θ of the polymer wall 2 is desirably 5 degrees or more.

Next, a method for manufacturing the color liquid crystal display device of the present invention will be described with reference to FIG.

First, a black matrix (BM) 6 is formed on the glass substrate 1 to shield the gap between the red, green, and blue colored patterns from light (FIG. 2A). As the material of BM6, a material in which carbon fine particles were dispersed in an acrylic photosensitive resin was used. Thereafter, each of the red, green, and blue colored resin layers 7 was sequentially formed (FIG. 2B). The film thickness is BM6,
Each of the colored resin layers 7 was set to 1.0 μm, applied to the glass substrate 1 by spin coating, and formed into a predetermined pattern by photolithography.

Thereafter, an overcoat layer 5 is formed by spin coating to a thickness of 2.0 μm,
A TO film was formed to a thickness of 3000 angstroms by sputtering and then patterned to form an ITO signal electrode 4 (FIG. 2c).

Further, two polymer wall patterns were transferred and formed by photolithography (FIG. 2d). Polymer wall 2
As a material for the above, a material obtained by thermocompression bonding a dry film resist 10 containing 5.5 μm diameter spacer beads made of transparent plastic as shown in FIG. 3 onto a substrate 1 using a laminator was used. The process of forming the polymer wall 2 is described below.
This will be described with reference to FIG.

(A) First, dry film resist 10
The cover film 15 is peeled off, and the surface of the photosensitive resin layer 14 is pressed and heated and bonded to the substrate 1 using a laminator; (b) The base film 11 is bonded to the cushion layer 12
(C) The resist is exposed on the substrate 1 by proximity exposure using a photomask 16 and ultraviolet rays.
7 is exposed and patterned. This exposure was performed under such conditions that the polymer wall material (that is, the photosensitive resin) immediately below the spacer beads 3 was sufficiently photopolymerized by ultraviolet rays. (D) Development was performed using a CD developer made by Fuji Ohlin. When rinsing is performed by high-pressure spray of pure water, the spacer beads 3 remain only in the portion where the polymer wall is formed (ie, the photopolymerized photosensitive resin layer 14). Then, at 240 ° C, 60
A minute post-bake was performed.

The liquid crystal area was 150 μm × 150 μm. The cross-sectional taper angle θ of the polymer wall 2 can be adjusted to 5 by adjusting the distance between the mask 16 and the substrate 1 (proximity gap) during proximity exposure and optimizing the development conditions.
And 45 degrees. The reason is,
When the angle is less than 5 degrees, the force for regulating the alignment of the liquid crystal molecules in an axisymmetric manner is weak, and the deterioration of the viewing angle characteristics becomes remarkable. Also, 45
On the other hand, when the temperature is higher than that, the disorder of the orientation near the polymer wall 2 becomes conspicuous, and the contrast is significantly lowered due to light leakage during black display.

Next, a polyimide resin J
ALS-204 (made by Japan Synthetic Rubber) is spin-coated,
A vertical alignment film 8 was formed. Similarly, a vertical alignment film 8 was formed on the counter substrate 9 side, and then bonded to the substrate 1 on which a color filter was formed (FIG. 2E).

Further, an n-type liquid crystal material (Δε = −4.0, Δn = 0.08, a cell gap of 5.5 μm, and a twist angle inherent to the liquid crystal material such that a 90 ° twist is formed between the substrates as a liquid crystal layer. ) To complete the liquid crystal cell.

(Embodiment 2) FIGS. 5A and 5B
As shown in (1), a TN type liquid crystal display device can be prepared by using the dry film resist 10 of the present invention as a resist for the R, G, B colored resin layer 7 and the black matrix layer 6, respectively.

[0043]

According to the dry film resist of the present invention, the spacer can be formed simultaneously with the formation of the resin layer.
The number of processes can be greatly reduced.

Further, when the method of manufacturing a liquid crystal display device according to the present invention is used, compared with the conventional method of manufacturing a liquid crystal display device using the ASM mode, the step of forming columnar projections can be reduced and the uniformity of the cell thickness can be reduced. Since it can be greatly improved, improvement in display quality, cost reduction by reducing the number of processes, and further improvement in yield can be expected.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a structure of one embodiment of a liquid crystal display device of the present invention, wherein (a) and (b) are a cross-sectional view and a plan view, respectively.

FIG. 2 is a diagram illustrating a manufacturing method of an embodiment of the liquid crystal display device of the present invention.

FIG. 3 is a schematic view showing a structure of an embodiment of a dry film resist of the present invention, wherein (a) shows a case where the bead diameter is equal to the sum of the thicknesses of a photosensitive resin layer, an oxygen barrier layer and a cushion layer; (B) is a case where the bead diameter is smaller than the sum of the thicknesses of the photosensitive resin layer, the oxygen blocking layer and the cushion layer.

FIG. 4 is a view showing a step of forming a polymer wall using the dry film resist of the present invention.

5A and 5B are schematic views showing a liquid crystal display device according to another embodiment of the present invention, wherein FIG. 5A shows a case where the dry film resist of the present invention is used as a color filter resist, and FIG.
Shows the case where the dry film resist of the present invention was used as a black matrix resist.

FIG. 6 is a schematic view showing the structure of a conventional dry film resist.

FIG. 7: Mixing spacer beads in a liquid resist,
It is a figure explaining a subject when this is applied to a substrate.

FIG. 8 is a diagram illustrating a method of manufacturing a conventional liquid crystal display device.

FIG. 9 is a schematic sectional view of a conventional color filter.

[Explanation of symbols]

 1,308 glass substrate 2,317 polymer wall 3 spacer beads 4,333 ITO electrode 5,332 overcoat 6,331 black matrix 7,330 colored resin layer 8,321 vertical alignment film 9,302 counter substrate 10 dry film Resist 11 Base film 12 Cushion layer 13 Oxygen blocking film 14 Photosensitive resin layer 15 Cover film 16 Photomask 17 Exposure area 18 Heat roll 20 Color filter 21 Photosensitive resin 22 Photosensitive resin film thickness 30 Liquid crystal display 315 Liquid crystal area 316 Liquid crystal Material 320 columnar projection

Continuation of the front page (72) Inventor Nobuaki Yamada 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka F-term (reference) 2H025 AB11 AB17 AD01 AD03 DA01 DA40 EA08 2H088 FA02 MA17 2H089 LA07 NA14 QA12 QA14

Claims (4)

[Claims] 1. A dry film resist comprising a base film serving as a support, spacer beads for defining a cell thickness dispersed on the base film, and a photosensitive resin layer formed on the base film. . 2. The dry film resist according to claim 1, wherein said spacer beads are spherical. 3. The method according to claim 1, further comprising a cover film formed on the photosensitive resin layer, wherein a diameter of the spacer bead is equal to or less than a distance between the base film and the cover film. The dry film resist according to claim 1. 4. A liquid crystal display comprising: a pair of substrates; and a liquid crystal layer sandwiched between the pair of substrates, wherein the liquid crystal layer is a polymer on a color filter formed on at least one of the pair of substrates. The liquid crystal device has a plurality of liquid crystal regions divided by walls, and liquid crystal molecules in the plurality of liquid crystal regions are axially symmetrically aligned around an axis perpendicular to the pair of substrates, and the polymer wall is formed on the substrate. A method for manufacturing a liquid crystal display device, comprising a transparent resin layer having a forward tapered inclined portion with respect to the polymer beads, wherein spacer beads that define the cell thickness of the pair of substrates are fixed by the polymer wall, On at least one of the pair of substrates, a base film serving as a support, spacer beads for defining a cell thickness dispersed on the base film, and a photosensitive resin formed on the base film Dora with layers Film resist sticking Keru step, and a step, to create the polymer wall is patterned by photolithography to the dry film resist method.