JPH11202121A - Manufacturing method of color filter - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method for manufacturing a color filter having a small thickness distribution in each color. SOLUTION: In a method of manufacturing a color filter in which a plurality of color resists are applied on a substrate and patterned to form a plurality of color filters, a rate index C of the color resist is represented by the following formula (1). Wherein the rate indexes of the color resists of a plurality of colors are set substantially equal for the plurality of color resists when the resist is applied. S = B × R ^C (1) (where S is the shear stress of the color resist (P
a) and B are the viscosity coefficients of the color resist, R is the shear rate (1 / s) of the color resist, and C is the rate index of the color resist. )

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color filter used for a liquid crystal display device or the like.

[0002]

2. Description of the Related Art In a color filter used in a liquid crystal element, a thickness difference between adjacent colors (inter-color step) is determined at least as a management accuracy based on requirements for driving characteristics of a liquid crystal and spectral characteristics of the filter. It is required to keep it at 1/15 to 1/30 (1/10 or less of the cell gap).
(Japanese Unexamined Patent Publication No. 63-60424) Incidentally, in a chiral smectic liquid crystal having the narrowest cell gap,
The difference between colors is required to be less than 1000 °. In some cases, a flattening film is formed on the color filter in order to reduce the level difference between colors. However, if the level difference is too large, flattening cannot be performed sufficiently. If the step of the color filter is too large, an extra step such as mechanical polishing is required.

At present, a method of manufacturing a color filter used for a liquid crystal display element adopts a method of applying a color resist corresponding to each color of the color filter on a substrate and patterning the resist into a predetermined shape by photolithography or the like. However, spin coating, roll coating, various printing methods, and the like are generally used as a method of applying a color resist that greatly contributes to the control of the film thickness of the color filter as described above. Regardless of the method, as means for controlling the film thickness to be formed, it is important to control the apparatus conditions based on the coating principle of each apparatus, the liquid properties at the time of coating, the environmental conditions, and the surface state of the object to be coated.

In film formation by such a coating method, Regarding the liquid properties of the coating liquid, its viscosity has conventionally been general and almost the only control item. For this reason, various types of measuring instruments such as E-type and B-type rotational viscometers and capillary-type viscometers such as Ostwald viscometers have been developed, and can be selectively used depending on the main purpose such as accuracy and simplicity. Thickness management has been done.

[0005]

However, in the case of a coating solution in which a coloring material is finely dispersed, such as a varnish (color resist) for a color filter, a shear stress (shear stress) and a shear rate (shear speed) at the time of coating are required. In addition to the non-Newtonian property that the viscosity changes depending on the color, the viscosity has a time dependency, and the degree differs depending on the color.
On the other hand, the viscosity measured using the above-mentioned viscometer is the viscosity at a constant shear rate, and when this viscosity is used to control the central value in the substrate or the minimum film thickness,
The following disadvantages occur.

[0006] 1. The film thickness distribution in the substrate is formed from the center of the spin coating toward the peripheral portion, and the degree varies depending on the color. 2. In a coating method in which a liquid is kneaded between rolls such as a roll coat, the film thickness changes within a lot, and the degree varies depending on the color.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. An object of the present invention is to apply a color resist having a non-Newtonian property by appropriately controlling the film thickness variation at the time of application, and apply each color. It is an object of the present invention to produce a color filter having a small film thickness distribution in the above.

[0008]

That is, the present invention relates to a method of manufacturing a color filter in which a plurality of color resists are coated on a substrate and patterned to form a plurality of color filters. When the index C is represented by the following formula (1), a rate index of a plurality of color resists is set to be substantially equal for a plurality of color resists at the time of resist application.

[0009]

S = B × R ^C (1) (where S is the shear stress of the color resist (P
a) and B are the viscosity coefficients of the color resist, R is the shear rate (1 / s) of the color resist, and C is the rate index of the color resist. )

The method for manufacturing a color filter of the present invention has the following features. The application of the color resist is performed by a spinner. The application of the color resist is performed by a roll coater.

The rate index C of the color resist for each color of the color filter is set to fall within a range of 0.96 to 1.0 l. The range of the rate index C of the color resist for each color of the color filter and the shear rate R to be analyzed is 10 to 300 (1
/ S).

The color resist is at least one solution selected from the group consisting of γ-butyl lactone, N-methylpyrrolidone, diglyme and triglyme of a polyamino resin containing a photosensitive group.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of manufacturing a color filter according to the present invention is directed to a method of manufacturing a color filter in which a plurality of color resists are coated on a substrate and patterned to form a plurality of color filters. When the rate index C is expressed by the following equation (1), the rate index C obtained from the shear stress S (Pa) and the shear rate R (1 / s) of the color resist is fixed for a plurality of color resists. By adjusting the thickness within the range, the film thickness distribution in the substrate during spin coating and the time-dependent film thickness variation during roll coating are minimized, the film thickness variation for each color is managed, and the step between colors of the color filter is suppressed. Features.

[0014]

S = B × R ^C (1)

First, a method of obtaining the rate index C of the color resist will be briefly described. Analysis of rate index. CSL Rheometer (Carr
yMed). This device is a shear stress control type rheometer. Particularly, it has a wide shear stress application range and has excellent performance in controlling a low shear stress region.

Measurements were made at a cone angle of 2 degrees and a cone diameter of 6c.
The applied stress was increased from 1 Pa to 100 Pa in a shear stress sweep mode of 2 minutes at a setting of 21 ° C. using a measurement unit having a m and a gap of 5 μm, and data of a shear stress and a shear rate were taken in at a sampling frequency of 60 Hz. After measurement, the rate index is (1)
The analysis was performed using the equation (power law equation).

The actual measurement was carried out by a method called up-curve analysis in the case where the shear stress was increased. The rate index can also be obtained from a down curve analysis based on a measurement in which the shear stress is lowered. In the present invention, the rate index obtained from the up curve analysis is described unless otherwise specified. In addition, this analysis was performed in the shear rate range of 10 to 300 (1 / s).
This was used to determine the rate index, (1)
From the limit of the precision of the formula, the minimum is 10 (1 / s). As a result of performing a simulation from the spinner rotation speed, the substrate size, the color resist viscosity, and the thickness of the final liquid film, the maximum shear rate is 300 (1 / s). s).

FIG. 5 and FIG. 6 show the relationship between the rate index of the color resist and the thickness distribution of the spin coat film in the substrate.
It was found that there was a correlation as shown in FIG. FIG.
Three types of color resists having different rate indices R (A: R = 0.913, B: R = 0.907, C: R =
0.942) and the distribution from the spinner rotation center to the film thickness. It can be seen that the smaller the rate index, the greater the climax at the center. When a color filter is formed with these three types of color resists, the distribution of the film thickness with respect to the center of rotation of the spinner greatly differs depending on the color, so even if the average value or the film thickness at a specific portion is managed for each color. In the case of a color filter formed of a plurality of colors, a large color step occurs.

FIG. 6 shows the relationship between the value of the rate index and the variation of the film thickness (difference between the maximum film thickness and the minimum film thickness). It can be seen that there is a correlation between the rate index and the value of the film thickness variation, and that the value of the film thickness variation is almost the same if the rate index is closer.

It is desirable to set the rate index C of the color resist for each color of the color filter to fall within a range of 0.96 to 1.0 l, preferably 0.98 to 1.00. By setting the rate index of the color resist in the above range, the step between the colors of the color filter is extremely small, and is at most 1000 ° or less.

The color resist used in the present invention is a polyamino resin containing a photosensitive group, such as γ-butyllactone, N
At least one solution selected from the group consisting of -methylpyrrolidone, diglyme and triglyme is preferred.
A specific example is Lithocoat 1012 series (manufactured by Ube Industries, Ltd.).

The pigment contained in the color resist is not particularly limited as long as it can obtain desired spectral characteristics among organic pigments, inorganic pigments and the like.
In this case, each material can be used alone or as a mixture of some of them. Also,
Organic pigments are preferred in view of the color characteristics and various properties of the color filter.

Examples of the organic pigment include azo pigments such as soluble azo, insoluble azo and condensed azo pigments, phthalocyanine pigments, and indigo, anthraquinone, perylene, perinone, dioxazine, quinacridone, and the like. Condensed polycyclic pigments including isoindolinone-based, phthalone-based, methine-based, azomethine-based, and other metal complex-based pigments, or mixtures of some of these are used.

As an example, a color resist is prepared by blending the above-mentioned pigment having desired spectral characteristics with the above-mentioned photosensitive polyamino resin solution at a ratio of about 10 to 50%, and sufficiently applying ultrasonic waves or a three-roll mill. After dispersing in
It is prepared by removing large particles with a filter.

In the method for manufacturing a color filter according to the present invention,
The color resist is coated on a substrate by a coating device such as a spinner or a roll coater, and is formed into a pattern by a photolithography process. The thickness of the layer is determined according to desired spectral characteristics. Approximately 2.0 μm, preferably approximately 1.3 μm to 1.7 μm.

The color resist described above can be applied to an appropriate substrate, for example, a glass plate, a transparent resin plate, a resin film, or a CRT display surface, a light receiving surface of an image pickup tube, CCD, B
On wafers with solid-state imaging devices such as BD, CID, and BASIS, contact-type image sensors using thin-film semiconductors, liquid crystal display surfaces, photoconductors for color electrophotography, and substrates for electrochromic (EC) display devices. Can be formed.

When it is necessary to further increase the adhesiveness between the color resist and the underlying substrate, a colored resin pattern is formed on the substrate in advance with a thin coating with a silane coupling agent or the like, or It is more effective to form a color resist by using a resin to which a silane coupling agent or the like is added in a small amount.

Hereinafter, a method for forming a color filter of the present invention will be described with reference to the drawings. FIG. 7 is a process chart showing one embodiment of the method for manufacturing a color filter of the present invention. This figure shows a process of forming pixels of three colors of R (red), G (green), and B (blue).

First, as shown in FIG. 7 (a), a first colored resin layer 2 is formed on a glass substrate 1 by using a color resist in which a coloring material is dispersed in a photosensitive polyamino resin.
Is applied to a predetermined thickness using a spinner, and prebaked under appropriate temperature conditions. Next, as shown in FIG. 7B, the light 8 having the sensitivity of the photosensitive colored resin (for example, a high-pressure mercury lamp or the like) passes through the photomask 3 having a predetermined pattern shape corresponding to the pattern to be formed. The colored resin layer 2 is exposed to light to cure the pattern portion.

Next, as shown in FIG. 7C, the colored resin layer 2 having the photo-cured portion 2a is coated with a developer 4 (for example, an N-methyl-2-pyrrolidone-based solvent) that dissolves only the unexposed portion. Rinsing treatment (for example, 1,1,1-trichloroethane or the like) is performed. Next, post bake processing is performed, and FIG.
A patterned colored resin layer 5 as shown in (d) can be obtained.

When a color filter composed of two or more colors is formed, the color filters shown in FIGS. 7A to 7D are further changed as necessary, that is, according to the number of colors of the color filters used. Is repeated using color resists in which pigments corresponding to the respective colors are dispersed. For example, the patterned colored resin layers 5 (R), 6 (R) of different colors as shown in FIG. G) and 7 (B) color filters can be formed.

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 A color resist in which a coloring material is dispersed in a photosensitive polyamino resin is spin-coated and patterned repeatedly to form a color sequentially. Steps between adjacent colors have been eliminated.

According to the process shown in FIG. 7, a color filter was prepared under the conditions shown in Table 1. The substrate used was blue plate glass of 450 mm × 550 mm, and the color resist used was Lithocoat 1012 series (manufactured by Ube Industries, Ltd.). This resist is obtained by adding methyl-2-pyrrolidone or / and γ-
Red with butyl lactone (selected for each color)
It is a blue and green pigment dispersion photosensitive polyamino resin solution.

[0035]

[Table 1]

(Note 1) Pa-EL3 (manufactured by Ube Industries, Ltd.) was used as a developer. (Note 2) US indicates ultrasonic wave application.

Table 2 shows the viscosity and rate index of each color resist. Measurement and analysis are performed using Carime (Car
The measurement was performed using a CSL type stress control type rheometer manufactured by ri-Med) with a shear rate R in the range of 10 to 300 (1 / s). Table 2 also shows a pure in-plane film thickness difference (maximum film thickness−minimum film thickness) and a central value when each color is formed independently. The film thickness was measured using a stylus type film thickness meter.

[0038]

[Table 2]

FIG. 1 shows the in-plane thickness distribution of each color plane of the color filter formed under the above conditions, and FIG. 2 shows the distribution of the step between colors. The maximum film thickness step at this time was 600 °, which sufficiently satisfied the requirement of 1,000 ° or less. The horizontal axis in FIGS. 1 and 2 indicates the distance (mm) from the center of the spinner during resist coating.

Comparative Example 1 Example 1 was repeated except that the viscosity of the color resist was adjusted as shown in Table 3 and the spin coating conditions were changed to adjust the film thickness.
A color filter was produced in the same manner as described above.

[0041]

[Table 3]

FIGS. 3 and 4 show the evaluation results. FIG. 3 shows the in-plane film thickness distribution of each color, and FIG. 4 shows the in-plane distribution of the step between colors.
At this time, the maximum step between colors was 1250 °, and although the center value of the film thickness was sufficiently controlled, the step between colors was 1000 °.
Å The following requirements could not be satisfied. The horizontal axis in FIGS. 3 and 4 indicates the distance (mm) from the center of the spinner at the time of resist application.

Example 2 When a color resist was applied by roll coating, the rate indices of the color resists were made uniform to eliminate variations in lot thickness differences among the colors. The coating process of FIG. 7 was performed by roll coating.

The substrate used was a blue plate glass of 450 mm × 550 mm, and the color resist used was Lithocoat 1012 series (manufactured by Ube Industries, Ltd.). Transfer speed 1500mm /
roll coating under the conditions of 1.6 mm in doctor roller pushing amount and 0.13 mm backup roller pushing amount, prebaking (80 ° C., 10 minutes), exposure (high pressure mercury lamp, red: 600 mJ, blue: 500 mJ, green: 90)
A color filter was formed under the conditions of 0 mJ, development (with US + oscillation), and post-baking (250 ° C., 10 minutes).

The viscosity and rate index of each color resist were measured and analyzed in the same manner as in Example 1. Table 4 shows the results.

[0046]

[Table 4]

As shown in Table 4, the rate index of each color resist is set in the range of 0.96 to 0.98, and the difference between the up curve analysis value and the down curve analysis value of the rate index is 0.01. The materials were adjusted to be within.

In the color filter formed under the above conditions, the variation in the film thickness of each color in the lot is 1000 ° and the maximum variation in the film thickness between the lots is 1500 °. The maximum was reduced to 1,000 mm. This is because physical properties such as viscosity change with lots as color resists continue to be kneaded with a roll coater, and film thickness varies with lots even under the same conditions. It is considered that the variation tendency becomes closer for all the colors and the film thickness of each color becomes almost the same in the same lot. As a result, it is considered that the step between the colors is suppressed to be small in all the lots.

[0049]

As described above, according to the present invention,
It is possible to supply color filters for liquid crystal display elements with high reliability and high durability without color unevenness on a large screen.At the same time, the step between colors is eliminated, eliminating the need for mechanical polishing.
There are effects such as simplification of the process, cost reduction, and prevention of a decrease in the non-defective product rate due to contamination of foreign matter.

In the example applied to the roll coating method,
It expands the range of manufacturing processes and enables the introduction of a method with higher productivity and lower cost. As described above, by managing the coefficient that is directly linked to the behavior in the application process of a non-Newtonian fluid such as a color resist, it greatly contributes to stabilization of the production line.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a film thickness distribution in a substrate for each color according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a step difference distribution between colors in a substrate according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a film thickness distribution in a substrate for each color according to Comparative Example 1.

FIG. 4 is a diagram illustrating a step distribution between colors in a substrate according to Comparative Example 1.

FIG. 5 is a diagram showing a film thickness distribution in a substrate of a spin coat film made of materials having different rate indexes.

FIG. 6 is a diagram showing a relationship between a rate index and a difference in thickness of a spin-coated film in a substrate.

FIG. 7 is a process chart showing one embodiment of a method for manufacturing a color filter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Colored resin layer 2a Photocured part 3 Photomask 4 Developer 5, 6, 7 Patterned colored resin layer 8 Light

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayoshi Asami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. A method of manufacturing a color filter, in which a plurality of color resists are coated on a substrate and patterned to form a plurality of color filters, a rate index C of the color resist is calculated by the following equation (1). A method of manufacturing a color filter, wherein, when expressed, a rate index of a plurality of color resists is set to be substantially equal for a plurality of color resists at the time of resist application. S = B × R ^C (1) (where S is the shear stress of the color resist (P
a) and B are the viscosity coefficients of the color resist, R is the shear rate (1 / s) of the color resist, and C is the rate index of the color resist. ) 2. The method according to claim 1, wherein the application of the color resist is performed by a spinner. 3. The method according to claim 1, wherein the application of the color resist is performed by a roll coater. 4. The method according to claim 1, wherein the rate index C of the color resist for each color of the color filter is set to fall within a range of 0.96 to 1.0 l. 5. The color filter according to claim 1, wherein the range of the rate index C of the color resist for each color of the color filter and the shear rate R to be analyzed is 10 to 300 (1 / s). Production method. 6. The color resist according to claim 1, wherein the color resist is at least one solution selected from the group consisting of γ-butyl lactone, N-methylpyrrolidone, diglyme and triglyme of a polyamino resin containing a photosensitive group. Item 7. A method for producing a color filter according to Item 1.