JPH0588011A - Production of color filter - Google Patents

Abstract

PURPOSE:To produce the color filter which is the color filter of 4 colors; red, green, blue, and white, formed by using a photosensitive resin mainly consisting of polyimide and polyamide and hardly generates the gap defect of a panel even when the color filter is used for the panel of a narrow cell gap. CONSTITUTION:Picture element patterns 1 to 4 of white, red, green, and blue are formed by patterning the photosensitive resin essentially consisting of the polyamide or polyimide and the photosensitive colored resins prepd. by dispersing pigments into this resin on a substrate by a photolithographic stage. The white pattern 1 among the picture element patterns 1 to 4 of these four colors is formed first at this time or if this pattern is formed second, the pattern is formed in the positions not adjacent to the picture element pattern formed first, for example, the green 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter manufacturing method, and more particularly to a color filter manufacturing method suitable for a color display.

[0002]

2. Description of the Related Art Conventionally, as a color filter, a mordant layer made of a hydrophilic polymer such as gelatin, casein, mulberry or polyvinyl alcohol is provided on a substrate, and the mordant layer is dyed with a dye to form a colored layer. A dyeing color filter that does is known.

In such a dyeing method, many dyes can be used, and it is relatively easy to meet the spectral characteristics required for a color filter. However, in the dyeing process of the mordant layer, a dye bath in which the dye is dissolved is used. It employs a difficult wet process of immersing a mordant layer in it, and has a complicated process of providing an intermediate layer for dye protection for each color, which has the drawback of lowering the yield. Further, the heat resistance of the dyeable dye is relatively low at about 150 ° C. or less, and it is difficult to use when heat treatment is required for the filter, and the heat resistance, light resistance, etc. of the dye film itself. It also has the drawback of poor reliability.

On the other hand, conventionally, a color filter using a colored resin in which a certain colored material is dispersed in a transparent resin is known.

Such color filters are disclosed, for example, in Japanese Patent Laid-Open Nos. 58-46325 and 60-78401.
JP, JP-A-60-184202, JP, JP-A-60
-184203, JP-A-60-184204, JP-A-60-184205, etc., printing using a colored resin material in which a coloring material is mixed with a polyamide or polyimide resin. how to,
Alternatively, it can be formed by a method in which a mask of resist is provided on the colored resin film and then the colored resin film is etched.

Further, JP-A-57-16407, JP-A-57-74707, and JP-A-60-12.
As disclosed in Japanese Patent No. 9707, etc., a color filter can be formed by a photolithography process using a photosensitive colored resin film in which a coloring material is mixed with a photosensitive resin.

These color filters can be said to be useful color filters because they can use materials having higher reliability than the dyed color filters and can be formed by a relatively simple method.

Organic pigments to be mixed include soluble azo pigments,
Insoluble azo pigments and condensed azo pigments, phthalocyanine pigments, and condensed polycyclic pigments including indigo pigments, anthraquinone pigments, perylene pigments, perinone pigments, dioxazine pigments, quinacryton pigments, and other metal complex pigments are used.

A color liquid crystal display element has a large number of pixels functioning as optical shutters formed on the red (R), green (G) and blue (B) filters, and displays three colors as one pixel. Are doing. In order to display as many colors as possible in such a system, gradation control for each pixel is necessary, but since stepless gradation control is particularly difficult with a ferroelectric liquid crystal, gradation control of only two values is performed. There is.
In principle, with this gradation control of only two values, one picture element can display up to eight colors.

Japanese Unexamined Patent Publication No. 2-118521 proposes to add white (or transparent) to the above three colors to form one picture element with four colors. According to this four-color filter method, gradation control of only two values is performed, and the eight-color filter method
It is possible to display 14 colors by adding 6 bright colors (light red, light green, etc.) excluding white and black to the color display, and 15-16 colors by adding achromatic colors with different brightness (luminance). Become.

[0011]

By the way, by using the above-mentioned photosensitive resin with or without mixing of coloring materials, R, G and B are mixed.
And W (red, green, blue, and white (or transparent)) pixel patterns are formed, when a pattern of another color is formed after the white pattern, the residue of the other color remains on the white pattern. It was formed as late as possible. With respect to this residue, it has become possible to clear it by removing the residue in recent years, but as a custom, the formation of the white pattern remains as a subsequent step.

When a liquid crystal display panel having a wide cell gap such as TN or STN (for example, 6 μm or more) is manufactured, there is no problem in the method of forming the white pattern later. However, in a panel having a narrow cell gap (for example, less than 6 μm) such as a ferroelectric liquid crystal display panel, when a conventional color filter that forms a white pattern after forming a pixel pattern of another color is used, When forming a panel by forming an electrode or the like on the counter substrate and a counter substrate on which a counter electrode or the like is formed, and then injecting liquid crystal into the cell to form a panel, a cell gap defect occurs, a panel alignment defect, There are inconveniences such as a short circuit between the upper and lower electrodes, coloring, and a defect such as a decrease in driving margin of the liquid crystal during driving.

That is, in a panel having a narrow cell gap,
In the color filter formed by using the photosensitive coloring resin composed of the coloring material and the photosensitive resin as described above, the photosensitive resin mainly composed of polyimide or polyamide is used, and ordinary RGB (red, green, blue) is used. In the case where white (or transparent) pixels are provided in addition to the above, if the formation order of each color pixel pattern is incorrect, a panel using such a color filter causes a gap defect, which is very inconvenient as a display.

The present invention has been made in view of the above problems in the prior art, and has excellent heat resistance and light resistance in which an RGBW pattern is formed using a photosensitive resin mainly containing polyimide or polyamide. It is an object of the present invention to provide a method for manufacturing a color filter that is a simple four-color filter that is less likely to cause a panel gap defect even when used in a panel having a narrow cell gap.

[0015]

To achieve the above object, in the present invention, a photolithographic process is performed on a substrate by using a photosensitive coloring resin in which a pigment is dispersed in a photosensitive resin mainly containing polyamide or polyimide. Patterning by
In addition to forming red, green and blue pixel patterns, a photosensitive resin mainly containing polyamide or polyimide and not containing a pigment is used to form a white (or transparent) pixel pattern by patterning on a substrate by a photolithography process.
In a method of manufacturing a color filter including four color pixel patterns of red, green, blue and white, the white pixel pattern is formed in a state where each white pixel is not adjacent to a pixel of another color. To do.

Specifically, a white pixel pattern is formed in the first color, or a pixel pattern of red, green, or blue is formed as the first color, and then the white pixel pattern is formed in the second color. It is formed at a position not adjacent to the pixel pattern formed for the first color.

The present invention is particularly suitable for use in a liquid crystal display panel having a narrow cell gap of less than 6 μm.

[0018]

The polyamide or polyimide-based photosensitive resin material used in the present invention has good heat resistance and can be subjected to a high temperature treatment in a subsequent step. For example, since it is possible to increase the substrate heating temperature during ITO film formation on the color filter formed of these materials and the firing temperature during alignment film formation,
A good display can be obtained. In particular, when manufacturing a ferroelectric liquid crystal panel, it is desirable that the baking temperature of the alignment film is 250 ° C. or higher, and thus these materials are indispensable.

On the other hand, the ferroelectric liquid crystal, unlike the normal TN liquid crystal, is difficult to control stepless gradation, so that it is usually binary-controlled. Therefore, RGB (red, green, blue) alone has a small number of colors to perform multicolor display with this type of liquid crystal. Therefore, it is necessary to increase the number of colors by providing white or transparent pixels. The white (or transparent) pixels are formed by using a transparent resin, but when forming the white pixel pattern, the white pixel portion is sandwiched or surrounded by pixels of other colors. The resin applied on the
It becomes like 6 of (c). If patterning is performed in this state by the method shown in FIG. 2, the region 10 of FIG. 1C is photo-cured, resulting in a defect that the patterning edge rises as shown in FIG. 1B. In the figure, 1 is a white pixel, 2 and 3 and 4 are pixels of other colors (red, green and blue), 5 is a glass substrate, and 9 is a raised portion of the white pixel 1. This phenomenon occurs with colors other than white, but since other colors contain pigments, such raised portions do not have to become large. In the case of white, the height of the raised part is 70
About 00Å, other colors are usually around 2000Å.
Even if the insulating layer 17 as shown in FIG.
It means that there is a convexity around 0Å.

Ferroelectric liquid crystal has a cell gap of 1.5 μm.
The thickness is preferably m or less, but the above-mentioned protrusions cause a cell gap defect when forming a panel having such a narrow cell gap, and there is a panel alignment defect, a short circuit between upper and lower electrodes, coloring due to a gap defect, and driving. This has been a cause of various defects such as a decrease in the driving margin of the liquid crystal.

In the present invention, when a polyimide or a photosensitive resin mainly containing polyimide is used as a white pixel, each white pixel is prevented from being adjacent to other colors when forming a white pixel pattern. As shown in a), the swelling of each pixel pattern, particularly the white pixel pattern is reduced, and defects such as the cell gap defect can be prevented.

Examples of the present invention will be described below.

[0023]

Example 1 A color filter was manufactured by the method shown in FIGS.

First, as shown in FIG. 2A, a polyamide-based photosensitive resin (PA1000C manufactured by Ube Industries, Ltd. in this embodiment) was formed on a glass substrate (thickness: 1.1 mm) 5 by a spinner method. ) Was applied to form a photosensitive resin layer 6. Next, after prebaking this, the photomask 7
Was used for exposure (FIG. 2B), and the desired portion 6a of the photosensitive resin layer 6 was photocured (FIG. 2C). After that, a portion other than the desired portion 6a is removed by a developing process (see FIG.
(D)), white (or transparent) pixel 1 portion shown in FIG. 1 (a) was formed. Next, a similar process is performed, and FIG.
Pixels 3 to 4 of the other three colors (red, green and blue) were formed. The order of formation of the other three colors varies depending on the characteristics of the material used, that is, the adhesiveness, the size of the pigment contained, etc. (Manufactured by Mfg. Co., Ltd.), blue was formed next to white, and then green and red were formed successively, which caused less swelling at the end of the pattern, which causes a gap defect. However, even if the order of red, green, and blue was changed, the difference in swelling was slight, so the degree of gap defect did not substantially change.

A color filter having the pixel arrangement shown in FIG. 3C was formed by the above method. In FIG. 3C, one pixel is 190 μm square, and the interval between pixels is 10 μm.
μm. The results of measuring the surface shape of this color filter in the Y and X directions are shown in FIGS. 3 (a) and 3 (b). In addition, white (or transparent) is shown in FIGS.
The result of measuring the surface shape of the color filter when the pixel pattern is formed in the fourth color is shown.

As can be seen from FIG. 4, the swelling of the end portion of the white pattern of the color filter according to the conventional method is about 7,000.
It is Å. On the other hand, as can be seen from FIG. 3, the swelling at the end portion of the white pattern was about 3000 Å at the maximum, which was formed by the method according to the present invention.

Next, a liquid crystal panel having the structure shown in FIG. 6 was produced using the color filter thus formed. That is, the color filter 1 formed on the glass substrate 5a
8 is provided with an insulating protective layer 17, and further an ITO film and a metal auxiliary electrode film are provided and patterned to form the display electrodes 11a and the metal routing electrodes 12a in stripes, and the insulating layer 13a and the alignment film layer. After forming 14a, the display electrode 11b, the metal leading electrode 12b, the insulating layer 13b, and the counter substrate 5b on which the alignment film layer 14b is formed have a gap amount set to a value between 1.0 and 1.5 μm. Then, the liquid crystal panel was completed by injecting and sealing the ferroelectric liquid crystal 16 in this gap. In FIG. 6, 15
Is a cell gap material for setting a gap, and 19 is a light-shielding mask (metal film) for preventing light leakage from a gap between pixels. When this panel was driven, there were few gap defects in the pixels, so a display of excellent quality could be obtained.

[0028]

[Embodiment 2] The formation method is almost the same as in Embodiment 1,
In this embodiment, white is formed second. The pattern configuration is the same as in FIG. 3C, and with this configuration, the first color, that is, the pixel pattern that is not adjacent to the white pattern is green. It is not necessary to pay attention to the pattern of FIG. 3C, and the arrangement may be changed appropriately. The factors that determine the layout are mainly how the drive signal enters and the adhesion of the red, green, and blue resins other than white.

As described above, in this embodiment, the pixel pattern of each color was formed in the order of green → white (transparent) → blue → red using the photolithography process shown in FIG. The surface condition of the color filter at this time is shown in FIG.

As shown in FIG. 5 (a), a slight rise is seen at the end of the pattern in the vicinity of the white corners drawn by the green patterns existing diagonally. However, since the height of this bulge is 1000 to 1500 Å, there is practically no problem.

When this substrate was formed into a panel and driven in the same manner as in Example 1, a display of excellent quality was obtained.

[0032]

As described above, according to the present invention,
In a color filter that requires R (red), G (green), B (blue) and W (white) filter pixels, white is first
By forming it at a position where it may be the second color or the second color, but it is not adjacent to the first color, it is possible to prevent the pattern edge from rising at the time of white patterning, especially when manufacturing a panel with a narrow cell gap. It is possible to prevent defective cell gap. In the above-mentioned photosensitive resin, in general, white has higher adhesiveness than red, green, and blue containing pigments, and from this point, it is preferable to use white as the first color. By bringing white to the first color, defects due to poor adhesion of the first color can also be solved.

[Brief description of drawings]

1A and 1B are image diagrams of a surface state of a color filter manufactured by the present invention and a conventional method, respectively, and FIG. 1C is an image diagram when a white pixel pattern is formed by a conventional method.

FIG. 2 is an explanatory diagram showing an example of a method of manufacturing a color filter.

FIG. 3 is a diagram showing a surface state ((a) and (b)) of a color filter according to an embodiment of the present invention and a pixel arrangement diagram ((c)).

FIG. 4 is a diagram showing a surface state of a color filter manufactured by a conventional method.

FIG. 5 is a diagram showing a surface state of a color filter according to a second embodiment of the present invention.

FIG. 6 is an image diagram of a cross section of a liquid crystal panel.

[Explanation of symbols]

1: white pixel, 2: red pixel, 3: green pixel, 4: blue pixel,
5, 5a, 5b: glass substrate, 6: photosensitive resin film, 7:
Photomask, 10: Photocuring part of white pixel pattern, 11
a, 11b: display electrode, 12a, 12b: metal leading electrode, 13a, 13b: insulating layer, 14a, 14b: alignment film, 15: cell gap material, 16: liquid crystal, 17: protective film (insulating layer), 18 : Color filter, 19: Light-shielding mask (metal film).

Claims (5)

[Claims] 1. A patterning is performed on a substrate by a photolithography process using a photosensitive coloring resin in which a pigment is dispersed in a photosensitive resin mainly composed of polyamide or polyimide,
In addition to forming red, green and blue pixel patterns, a photosensitive resin mainly containing polyamide or polyimide is used to form a white pixel pattern by patterning on a substrate by a photolithography process using a photolithography process, red, green and blue. And a method of manufacturing a color filter composed of pixels of four colors of white, wherein the white pixel pattern is formed in a state where each white pixel is not adjacent to a pixel of another color. .. 2. The manufacturing method according to claim 1, wherein the white pixel pattern is formed first. 3. The red, green, or blue pixel pattern is formed first, and the white pixel pattern is formed second at a position that is not adjacent to the position where the first color is formed. The manufacturing method according to claim 1, wherein 4. The manufacturing method according to claim 1, wherein the color filter is formed on a cell inner surface side of a liquid crystal display panel having a narrow cell gap. 5. The manufacturing method according to claim 4, wherein the cell gap is less than 6 μm.