JPS61180203A - Production of color filter - Google Patents

Abstract

PURPOSE:To make much simpler the process for production and to make thinner and flatter a color filter by executing a post baking treatment after patterning at a high temp. within a range allowed by the heat resistance of a dye. CONSTITUTION:The temp. of post baking of the color pattern formed by patterning in the previous stage is made as high as possible within the range allowed by the heat resistance of the dye, for example, 190-300 deg.C to accelerate additionally the conversion to imide. The conversion to imide is progressed by the dehydration ring closure of a polyamic acid which is a polyimide precursor and the degree of the progress is higher as the baking temp. is made higher. The polyimide of such heating dehydration type does not complete the thorough conversion to imide unless said polyimide precursor is baked at about 400 deg.C. However the soln. prepd. by incorporating the dye for coloration into the polyimide precursor soln. is used to form the layer for forming the color pattern and therefore the upper limit temp. for post baking is limited by the heat resistance of the dye. The dye for coloration having the high heat resistance is thereupon selected.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method of manufacturing a color filter used in liquid crystal displays or image pickup devices, and in particular, a method for manufacturing a color filter used in a liquid crystal display, an image sensor, etc. The present invention relates to a simple process in which a layer for forming a color pattern can be formed without using a protective film.

(Prior Art) This type of color filter has a plurality of color patterns on one surface of a substrate such as a glass plate. In order to increase the resistance of color filters, it is effective to increase the resistance of each color pattern itself. Traditionally, as a basic material for color patterns,
It is known to use polyimide-based resins that are excellent in various resistances such as heat resistance and light resistance (particularly resistance to ultraviolet rays).

When polyimide resin is used as a pattern material, printing or photolithography techniques are used as the patterning method. The former is easy to print, but
In terms of surface precision and dimensional precision of the resulting pattern, the latter photolithography technique is far superior.

As a conventional example of photolithography technology, as shown in the process flow shown in FIG. Showa 59
(Refer to Publication No.-29225).

However, in the conventional technology using this dyeing, the process is complicated because patterning and dyeing are performed separately, and furthermore, the patterned polyimide resin is at least in a semi-cured state. There are some drawbacks, such as the difficulty of diffusing the dye into the dye.

Therefore, the present inventors have developed a technique to solve such difficulties by applying a solution made by mixing a coloring material into a polyimide resin solution to a substrate, and then applying photophosphorography to the colored polyimide resin layer formed thereby. He first proposed a method of patterning using technology (patent application 1986-20).
1.319). FIG. 4 shows an example of a process flow according to the proposed technology, and it will be understood that the process is considerably simplified compared to that shown in FIG. 3.

(Problems to be Solved by the Invention) According to the technology proposed above, each color pattern can be formed relatively easily, but each time each color pattern is formed, the previously formed color pattern is A protective film must be formed to protect it.゛That point is the third
The same applies to the conventional general method shown in the figure.

In order to further simplify the manufacturing process of a color filter, the present inventors focused on omitting the protective film and conducted various studies, and found the following.

That is, for example, if a second color pattern is formed without covering the first color pattern with a protective film, the first color pattern will be damaged when the second color coating liquid is applied, but the patterning This means that there is almost no damage during etching. Here, damage means, for example, cracks or wrinkles in the previous color pattern, such as the first color pattern, or
This is a phenomenon in which 9 dyes in the color pattern dissolve or the pattern itself dissolves. This phenomenon is considered to be caused by the solvent contained in the second color coating liquid.

An object of the present invention is to provide a color filter manufacturing technique that can omit the protective film by adding solvent resistance, that is, resistance to solvents that dissolve polyimide, to the color pattern in the previous stage.

(Means for Solving the Problems) In the present invention, the temperature of the post-baking of the pre-patterned color pattern is set as high as possible within the range allowed by the heat resistance of the dye, for example, 190 to 300°C to further improve imidization. Imidization, which is further promoted, proceeds through dehydration and ring closure of polyamic acid, which is a polyimide precursor, and the degree of this progress increases as the baking temperature increases. Such heat-dehydrated polyimide cannot be completely imidized unless it is baked at about 400°C. However, since the layer for forming the color pattern is formed using a solution containing a polyimide precursor solution mixed with a dye for coloring +4, the upper limit temperature of the post bake depends on the heat resistance of the dye. Regulated.

Therefore, it is best to select a dye for coloring that mixes well with the polyimide precursor solution and has high heat resistance. Suitable dyes are shown in Table 1 below.

Here, heat resistance of 250 °C means that the color tends to fade slightly if heat treated at a temperature of 250 °C for a long time, but it can actually be used for 250 °C.
The above means that even if heat treated at a temperature of 250° C. for a long time, there is no tendency for deterioration such as fading of color and it can be used.

(Operation) For example, change the pose 1-bake of the previous color pattern to 190
Since the treatment is carried out at a high temperature of about 300 DEG C., preferably about 250 DEG C., imidization of the color pattern in the previous stage is promoted and damage caused by the formation of the color pattern in the next stage can be sufficiently resisted.

Generally, color filters are red (R), green (G), blue (
In addition to the three primary colors of B), there are four color patterns including black (BQ), but the improvement in solvent resistance is not only between the first color pattern and the second color pattern. , second
The same is true between the color pattern and the third color pattern, as well as between the first color, second color, and third color, and between the first color, second color, third color, and fourth color. .

Therefore, in the present invention, as the process flow is shown in FIG. 1, it is possible to omit the entire process of forming a protective film for protecting the color pattern in the previous stage.

Furthermore, in addition to simplifying the manufacturing process, the present invention can provide an overall thin and flat color filter since there is no protective film.

This will be clear from FIG. 2, which shows the cross-sectional structure of a color filter obtained by the present invention. In Fig. 2, 1- is a glass plate, plastic plate, plastic film, or a substrate such as a semiconductor substrate on which electrical elements are formed, and 2 is a top coat made of gelatin, epoxy, or polyimide material. ,
Further, R, G, B, and BQ are patterns of red, green, blue, and black colors formed by photolithography technology.

Protecting the top layer] ・Tub coat 2 can be omitted by increasing the solvent resistance of all color patterns.

(Example) Using a glass plate coated with silica on the surface as the substrate 1, a color filter having the cross-sectional structure shown in FIG. 2 was manufactured under the following conditions.

Although the obtained color filter did not have a protective film, it was of good quality with no damage as described above observed in the BQ, B, and R color patterns in the previous stage.

(,) Formation of black pattern BQ Acid Black l 55 (Acid Black
155) and a polyimide precursor solution in a ratio of 1=10, an appropriate amount of solvent is added thereto, and a small amount of silane coupling agent is added to improve the adhesion to the substrate 1, thereby forming the first color black. A coating solution was prepared.

By dropping this black coating liquid onto one surface of the substrate 1 rotating at 200 rpm, a layer (about 1.0 to 1.5 μm thick) for forming the black pattern BQ was formed.

After pre-baking the layer, it is patterned using a positive type photoresist and then heated to 250°C for 30 minutes.
A post-baking process was performed for 0 minutes to form a black pattern BI1.

(b) Formation of blue pattern B Acid Blue 129 (Acid Blue 42
9), Solvent Blue 25 (Solvent Bl
ue 25), and polyimide precursor solution at 1.5
:0.1:10, an appropriate amount of solvent was added thereto, and a trace amount of a silane coupling agent was added to prepare a second color blue coating liquid. Apply this blue coating liquid onto the substrate 1 on which the black pattern BQ is formed.
A layer (about 1.0 to 1.5 μm thick) for forming the blue pattern B was formed by coating under the conditions of 000 rpm. After pre-baking these layers, they were patterned in the same manner as above, followed by a boost bake at 250° C. for 30 minutes to form blue pattern B.

(c) Formation of red pattern R Solvent Red 122 (Solvent Re
d 122) and a polyimide precursor at a ratio of 0.35:10, and a solvent and a silane coupling agent were added in the same manner as above to prepare a third color red coating solution. Apply this red coating liquid to both black and blue patterns B.
A layer (about 1.0 to 1.5 μm thick) for forming a red pattern R was formed by coating the substrate 1- on which Q and B were formed at 300 rpm.

After pre-baking and patterning such a layer, a red pattern R was formed by post-baking at 250° C. for 30 minutes.

(d) Formation of green pattern G Solvent Blue 25 (Solvent B),
ue 25), Solvent Yellow 77 (Sol
Vent Yellow 77) and a polyimide precursor solution were mixed in a ratio of 1:1.1:10, and a fourth color green coating solution was prepared by adding a solvent and a silane coupling agent in the same manner as above. . By applying this green coating liquid onto the substrate 1- on which the black, blue and red patterns BQ, B, and R are formed under the condition of 270 rpm, a layer (thickness) for forming the green pattern G is formed. A thickness of about 1.3 to 1.7 μm) was formed. After prebaking and then patterning these layers,
A green pattern G was formed by post-baking for 0 minutes.

Then, the entire surface of the substrate 1 on which each color pattern was formed was coated with a top coat 2.

In the above embodiment, the first to third color patterns are post-baked at the same temperature of about 250° C., but this is to facilitate temperature control of the heating furnace. Therefore, each borst bake temperature is
They can also be different depending on the heat resistance of the dye. In that case, it is preferable to form a material containing a highly heat-resistant dye in an earlier step.

(Effects of the Invention) In this invention, the post-bake treatment after patterning is performed at a high temperature within the range allowed by the heat resistance of the dye, so that it is possible to protect the color pattern that has already been formed in the previous stage. The next color pattern can be formed without forming a film, and the manufacturing process of the prior art, which eliminates the need for a dyeing process, can be further simplified, and the thickness of the color filter can be reduced. And flattening can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing an example of the process flow according to the present invention, FIG. 2 is a sectional view showing a color filter obtained by the present invention, and FIG. 3 is a process diagram showing the process flow of a conventional general dyeing method. FIG. 4 is a process diagram showing the process flow according to the previous proposal. 1-...Substrate, 2...Top coat, B...Blue pattern, R...Red pattern, G...Green pattern, B
fl...black pattern.

Claims (1)

[Claims] 1. When manufacturing a color filter having multiple color patterns on one side of a substrate, a layer for forming a color pattern is created using a solution consisting of a polyimide precursor solution mixed with a dye for coloring. In a method for manufacturing a color filter in which the layer is formed and patterned using photolithography technology, the previous color pattern is heat-treated at high temperature to increase the solvent resistance of the color pattern, and the color pattern in the previous stage is heated. A method for manufacturing a color filter, characterized in that patterning of a next-stage color pattern is performed without forming a protective film thereon.