JP5724219B2 - Manufacturing method of color filter substrate - Google Patents

Description

  The present invention relates to a method for suppressing cracks that occur when a transparent electrode is formed on a color filter in which colored pixels are arranged in a delta arrangement.

  FIG. 1 shows a cross-sectional structure of a typical color filter substrate used in a liquid crystal display device. The color filter substrate is formed by first forming a black matrix 2 as a light-shielding layer on the transparent substrate 1, and then arranging red, green 4, and blue 5 colored layers in the opening of the black matrix (hereinafter referred to as BM). The transparent electrode layer 6 is finally formed as the uppermost layer. Recently, photo spacers and alignment control protrusions may be formed at predetermined positions on the color filter.

  There are several methods for manufacturing a color filter substrate, such as an inkjet method, but a typical manufacturing method is to drop a colored photoresist on the central portion of the glass substrate 1 from the discharge port or from a slit-like nozzle on the substrate. Then, the glass substrate 1 is rotated by using a spin coater to form a film made of a thin colored resist, and a conventional photolithography technique is applied.

  In the arrangement pattern of colored pixels formed by applying the pigment dispersion method, red, green and blue colored layers formed in a strip shape are periodically arranged in stripes, red, blue formed in a substantially four-stroke shape, As shown in FIG. 2, there is a delta arrangement in which green colored pixels are spread in units of a set of three colors. Compared to the stripe arrangement, the delta arrangement is slightly difficult to manufacture colored pixels, but has an advantage that a natural color feeling can be obtained (see, for example, Patent Document 1).

  The delta arrangement will be described with reference to FIG. 2. The three different colored pixels 3, 4 and 5 are periodically arranged linearly in the horizontal direction, and the same colored pixel arrangement is shifted by half a pixel in the vertical direction. It is the one that was laid down. In this delta arrangement pattern, adjacent corners of two color pixels, for example, the corners of the pixels 4 and 5 and the side portions of the remaining one-color pixel 3 form an association portion 7 of three pixels. On the other hand, corner portions do not collect in the stripe-like colored pixel pattern.

By the way, when a transparent electrode layer 6 for driving liquid crystal (hereinafter also referred to as ITO) is formed on a color filter in which colored pixels are arranged in a delta arrangement, cracks 8 are formed in the transparent electrode layer on the pixel from the above-described meeting portion 7 as a starting point. There was a problem of entering. When closely observed, the corners of the colored pixels, which should ideally be at right angles, are actually not right angles but rounded and thin, and the corners 7 are minute depressions. I found out. The roundness of the corner itself and the thinning are inevitable as long as the colored pixels 3, 4, and 5 are manufactured by a photolithographic method using a photosensitive resin.

JP-A-8-110517

In view of the above, an object of the present invention is to provide means for suppressing the occurrence of cracks in the transparent electrode layer that originates from a dent generated at a portion where corners of colored pixels arranged in a delta arrangement meet.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a color filter substrate in which a colored pixel layer delta-aligned with a black matrix is formed on a substrate by a photolithography method, and then a transparent electrode layer is laminated. In the manufacturing method , a correction pattern for raising a dent generated in a portion where the corners of the colored pixels are adjacent to each other by using a photosensitive resin material for forming the colored pixels is a quadrilateral shape or a triangle along the dent portion. The color filter substrate manufacturing method is characterized in that it is formed into a shape .

According to the present invention, by embedding the depressions between the colored pixels, the transparent electrode layer in the depressions is formed with the same thickness as the surrounding colored pixels, so that the generation of cracks in the transparent electrode layer is suppressed and the liquid crystal display The image quality of the device is improved.
As an additional effect, the flatness of the color filter is improved, the alignment between the colored pixels is also improved, and the liquid crystal alignment on the pixels is not adversely affected, so that the display image quality is expected to be improved.

It is a figure of the cross-sectional view explaining the structure of a general color filter substrate. It is a figure explaining how to arrange the colored pixels of red, green, and amber in the delta arrangement. An example of a correction pattern for embedding a dent . (A) Colored pixel correction pattern, (b) Cross-sectional view when layer correction is performed with BM. The figure of the sectional view for demonstrating the condition where the site | part used as a dent was embed | buried beforehand.

  First, an outline of the present invention will be described with reference to the drawings.

When the laminated portion of the ITO and the colored layer in the meeting portion 7 between the colored pixels arranged in the delta arrangement shown in FIG. 2 is observed by FIB (field ion beam), the ITO film thickness of about 1400 mm on the pixel is the origin of the ITO crack. It has been found that the thickness of the thinned portion is about 1000 to about 70 to 70%. Furthermore, in this meeting part 7, the corners of the green and blue pixels are eluted during development and the film thickness is reduced to about 50% compared to the normal red, green, and blue colored pixel parts, and the relative thickness with respect to the surroundings. The pixel fringes (both dents and sides) were also slanted. In other words, in a small dent , the ITO film is difficult to be formed, and as a result, the ITO film thickness becomes thin. Due to the stress caused by the thermal history, shape anisotropy, etc. in the subsequent ITO baking process, non-uniform stress is applied to the ITO. In addition, it was assumed that cracks occurred and propagated from thin to thick.

Based on this observation and guess, the present invention is a portion where the photosensitive resin becomes recessed eluted during development to retrospectively buried by patterning a photosensitive resin or pre photosensitive resin sites will be made The thickness of the ITO film formed thereafter is kept equal to that of the surrounding pixel part, and uneven stress is applied to the ITO film. It is something that is not added. In the following, the case where the bottom is raised in advance will be mainly described, but this case is also referred to as “buried”.

Since the photolithographic method is applied to raise the portion corresponding to the dent in advance, a photosensitive resin composition is used as the embedding material. Therefore, it is desirable to use either a photosensitive resin material for forming a BM or a colored pixel. Of course, after forming the BM and the color filter, the resulting dents may be embedded with the above-mentioned photosensitive resin, or they can be formed together when forming photo spacers or alignment control projections. It is.

FIG. 3A schematically shows a case where the correction pattern 10 is formed so that the red coloring layer 3 extends to the concave portion at the same time when the red coloring pixel 3 is formed. Although it is not clear from the drawing, the same extended processing is performed for green and blue colored pixels. FIG. 3B illustrates a case where the BM layer is formed in advance and thickened in advance in a portion that can become a recess after the BM layer is formed. 4 (a) and 4 (b) show a state in which the dent of the part where the corners meet becomes flat when the bottom is raised beforehand.

If the thickness of the target member (for example, colored layer) and the thickness required to embed the dent are significantly different, patterning cannot be performed at the same time, but if a gray scale mask or the like is used, one exposure / development process is performed. Thus, it is possible to collectively form patterns having different thicknesses.

  Hereinafter, the present invention will be described with reference to the drawings in accordance with a color filter substrate manufacturing example.

(Preparation of substrate)
As the transparent substrate 1 used in the present invention, a glass plate such as soda lime glass, low alkali borosilicate glass or non-alkali aluminoborosilicate glass, or a resin substrate such as polycarbonate, polymethyl methacrylate, polyethylene terephthalate or the like is used. A glass substrate having a size of 200 cm × 150 cm excellent in transparency, strength, heat resistance, and weather resistance was used.

(Production of black matrix)
The BM 2 is provided in a matrix because the colored pixels are arranged in a delta arrangement on the substrate 1. The substrate 1 has a function of dividing the surface of the substrate 1 into a plurality of regions and preventing color mixture of light emitted from colored pixels regularly arranged in each of the many regions.

In the case of using a BM cured product as a material for raising the bottom in advance so as not to generate the dent 7 between the colored pixels, a regular photolithographic process is performed using an ordinary photomask to form BM2, and then the dent is embedded. A predetermined thickness was further laminated on the BM using a photomask having a dedicated pattern (see FIG. 3B).
When the negative black photosensitive resin described below was used, exposure was performed using a dedicated photomask having an opening of 15 μm × 12 μm set to be about 5 μm larger than the size of the recess .
In addition, when embedding a dent with the photosensitive resin for coloring pixels, it is not necessary to laminate | stack BM.

The photosensitive composition for BM formation was prepared by mixing the following materials.
Carbon black dispersion: 28.5 parts by weight of TPBK-2016 (manufactured by Mikuni Dye Co.) Resin: V259-ME (manufactured by Nippon Steel Chemical Co., Ltd.) 10.3 parts by weight Monomer: DPHA (manufactured by Nippon Kayaku Co., Ltd.) 2.58 parts by weight ・ Initiator: OXE-02 (manufactured by Ciba Specialty Chemicals) 0.86 parts by weight ・ Solvent: 92.0 parts by weight of propylene glycol monomethyl ether acetate Ethyl-3-ethoxypropionate 4.3 Part by weight / leveling agent: BYK-330 (by Big Chemie) 1.3 parts by weight

A coating film was formed on the glass substrate 1 by the slot coating method using the above BM-forming photosensitive composition, dried at 100 ° C. for 3 minutes, and then a black photosensitive layer having a thickness of 1.5 μm was produced. Thereafter, the black photosensitive layer obtained was irradiated with 200 mJ / cm ² of light from a high-pressure mercury lamp through a BM photomask, developed with a 2.5% aqueous sodium carbonate solution for 30 seconds, washed with water, dried, and then patterned. By baking at 230 ° C. for 60 minutes for fixing, a matrix-like BM 2 having a line width of 6 μm was formed at a predetermined position of the substrate 1 (FIG. 3B).

<Embedded recess >
Thereafter, the correction pattern 11 extending from the BM 2 by a predetermined area was formed by repeating the photolithography process using a dedicated photomask for embedding the recess . The finished size of the embedded resin cured product was 10 μm × 7 μm and the thickness was 1 μm.

<Formation of color filter>
When filling a dent with a cured photosensitive coloring material, if the colored pixel to be formed first is red, the red pixel and the embedded portion are formed simultaneously. Use a corrected version. As shown in FIG. 3A, a photomask with a correction pattern 10 protruding from the side of the red pixel 3 was used. This is because the side portion only elutes linearly during development and does not elute so as to be rounded. Incidentally, the pattern shape of the correction portion may be a quadrangular shape as shown in FIG. 3A, or may be a triangular shape along the recess. Alternatively, a corrected mask that protrudes from the corner may be used. Corresponding concave portions are buried at the time of the subsequent green pixel forming step and blue pixel forming step, respectively.

<Adjustment of red photosensitive composition>
A mixture having the following composition was uniformly stirred and mixed, then dispersed in a sand mill for 5 hours using glass beads having a diameter of 1 mm, and then filtered through a 5 μm filter to prepare a red pigment dispersion.
-Red pigment: C.I. I. Pigment Red 254 18 parts by weight (“Ilgar Forred B-CF” manufactured by Ciba Specialty Chemicals)
-Red pigment: C.I. I. Pigment Red 177 2 parts by weight (“Chromophthal Red A2B” manufactured by Ciba Specialty Chemicals)
・ 2 parts by weight of dispersant (“Ajisper PB821” manufactured by Ajinomoto Fine Techno Co.) ・ 50 parts by weight of acrylic varnish (solid content 20%)

Thereafter, a mixture having the following composition was stirred and mixed to be uniform, and then filtered through a 5 μm filter to obtain a red photosensitive composition.
-72 parts by weight of the dispersion-Resin: 28 parts by weight of a thermoplastic acrylic resin-Monomer: 12 parts by weight of DPHA (manufactured by Nippon Kayaku Co., Ltd.)-Initiator: Irgacure 907 (manufactured by Ciba Specialty Chemicals)
3 parts by weight-Sensitizer: EAB-F (Hodogaya Chemical Co., Ltd.) 1 part by weight-Solvent: 253 parts by weight of cyclohexanone

<Red pixel formation>
A coating film was formed on the glass substrate 1 on which BM2 was formed by the slit coating method using the above-mentioned red photosensitive composition, and after drying at 90 ° C. for 5 minutes, a red photosensitive layer having a thickness of 2 μm was prepared. The resulting red photosensitive layer is irradiated with 300 mJ / cm ² of light from a high-pressure mercury lamp through a delta photomask for forming a red layer, developed with an alkali developer for 60 seconds, washed with water and dried, and then the pattern is fixed. Therefore, the red pixel 3 (FIG. 3A) having the correction pattern 10 protruding at a predetermined portion was formed by baking at 230 ° C. for 30 minutes.
An alkaline developer having the following composition was used.
・ 1.5 parts by weight of sodium carbonate, 0.5 part by weight of sodium hydrogencarbonate, 8.0 parts by weight of anionic surfactant (Kao / Perylex NBL), 90 parts by weight of water

Next, a green pixel is formed. Also in this case, a mask provided with a correction unit is used.
<Adjustment of green photosensitive composition>
A mixture having the following composition was uniformly stirred and mixed, then dispersed in a sand mill for 5 hours using a glass bead having a diameter of 1 mm, and then filtered through a 5 μm filter to prepare a green pigment dispersion.
Green pigment: C.I. I. Pigment Green 36
(“Rionol Green 6YK” manufactured by Toyo Ink Co., Ltd.) 16 parts by weight / yellow pigment: C.I. I. Pigment Yellow 150
(Bayer's "Funcheon First Yellow Y-5688") 8 parts by weight Dispersant (Big Chemie "Disperbyk-163") 2 parts by weight Acrylic varnish (solid content 20%) 102 parts by weight

Thereafter, a mixture having the following composition was stirred and mixed to be uniform, and then filtered through a 5 μm filter to obtain a green photosensitive composition.
-128 parts by weight of the dispersion-Resin: 29 parts by weight of thermoplastic acrylic resin-Monomer: 14 parts by weight of DPHA (manufactured by Nippon Kayaku Co., Ltd.)-Initiator: Irgacure 907 (manufactured by Ciba Specialty Chemicals)
4 parts by weight-Sensitizer: EAB-F (Hodogaya Chemical Co., Ltd.) 2 parts by weight-Solvent: 257 parts by weight of cyclohexanone

<Green pixel formation>
A coating film was formed on the glass substrate 1 on which the BM2 and the red pixel 3 were formed by the slit coating method with the above-mentioned green photosensitive composition. After drying at 90 ° C. for 5 minutes, a green photosensitive layer having a thickness of 2 μm was produced. . The resulting green photosensitive layer is irradiated with 300 mJ / cm ^{2 of} high pressure mercury lamp light through a striped photomask for green layer formation, developed with an alkaline developer for 60 seconds, washed with water and dried, and then the pattern is fixed. For this purpose, the corrected green pixel 4 was formed by baking at 230 ° C. for 30 minutes. An alkaline developer having the same composition as that for forming the colored pixels was used.

<Preparation of blue photosensitive composition>
A mixture having the following composition was uniformly stirred and mixed, then dispersed in a sand mill for 5 hours using glass beads having a diameter of 1 mm, and then filtered through a 5 μm filter to prepare a blue pigment dispersion.
Blue pigment: C.I. I. Pigment Blue 15: 6
("Rionol Blue ES" manufactured by Toyo Ink Manufacturing Co., Ltd.) 3.6 parts by weight. Dispersant ("Sols Birds 20000" manufactured by Zeneca) 0.6 parts by weight. Acrylic varnish (solid content 20%) 22.1 parts by weight Part

Thereafter, a mixture having the following composition was stirred and mixed so as to be uniform, and then filtered through a 5 μm filter to obtain a blue photosensitive composition.
-28.3 parts by weight of the dispersion-Resin: 9.4 parts by weight of a thermoplastic acrylic resin-Monomer: 4.7 parts by weight of DPHA (manufactured by Nippon Kayaku Co., Ltd.)-Initiator: Irgacure 907 (Ciba Specialty Chemicals) Made)
1.4 parts by weight / sensitizer: EAB-F (manufactured by Hodogaya Chemical Co., Ltd.) 0.2 parts by weight / solvent: 26 parts by weight cyclohexanone 11 parts by weight 2-acetoxy-1-methoxypropane 20 parts by weight isopentyl acetate

<Blue pixel formation>
A coating film is formed on the glass substrate 1 on which BM2, red pixel 3 and green pixel 5 are formed by the slit coating method and the blue photosensitive composition is dried at 90 ° C. for 5 minutes. A photosensitive layer was prepared. The resulting blue photosensitive layer is irradiated with 300 mJ / cm ² of light from a high-pressure mercury lamp through a striped photomask for forming a blue layer, developed with an alkaline developer for 60 seconds, washed with water and dried, and then the pattern is fixed. Therefore, the blue pixel 5 was formed by baking at 230 ° C. for 30 minutes (FIG. 3B). An alkali developer having the same composition as the colored layer was used.

  Through the above steps, a color filter composed of BM2, red pixel 3, green pixel 4 and blue pixel 5 was formed on glass substrate 1.

<Formation of transparent electrode>
Next, 1400 mm of indium tin oxide (ITO) was laminated as the transparent electrode layer 6 on the color filter using a sputtering method, and then fired at 210 ° C. for 30 minutes.
When the correction pattern was put in the colored pixel and when the BM was laminated in the dent portion, no ITO crack was generated starting from the dent . The thickness of ITO was approximately 1400 mm. When the dent was not embedded, the ITO thickness of the dent was approximately 900 mm, and cracks were observed.

1. Glass substrate 2. Black matrix (BM)
3, red coloring pixel 4, green coloring pixel 5, blue coloring pixel 6, transparent electrode layer 7, meeting part ( dent )
8, crack 10, correction pattern (colored layer)
11. Correction pattern (BM)

Claims (1)

In the method of manufacturing a color filter substrate, a colored pixel layer that is delta-aligned with a black matrix is formed on a substrate by a photolithography method, and then a transparent electrode layer is stacked and manufactured.
By using a photosensitive resin material for forming colored pixels, a correction pattern for raising a dent generated in a portion where corners of the colored pixel are adjacent to each other is formed in a square shape or a triangular shape along the dent portion. producing how a color filter substrate according to claim.

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