JPH08137098A - Black matrix photoresist - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Photoresist capable of accurately forming a black matrix having a high light blocking rate of a fine pattern such as a lattice or stripe on a substrate, and a black matrix using the same A method for producing a substrate having the above and a method for producing a color filter using the substrate are provided. [Structure] A method for manufacturing a substrate having a black matrix, which comprises sequentially performing the following steps. (A) A step of applying the above-mentioned photoresist for black matrix on the surface of the substrate, (b) an exposure step of irradiating a light beam with a mask having a predetermined pattern overlaid, and (c) a developing step of removing the intermediate film of unnecessary portions. , (D) a step of reducing the light transmittance of the coating film by re-exposing or / and heat-treating the developed film, in the pixel portion of the substrate having a black matrix, which is obtained by the above production method,
A method for producing a color filter, which comprises forming a coating film of three primary colors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoresist for black matrix, a method for producing a substrate having a black matrix using the photoresist, and a method for producing a color filter using the substrate having the black matrix.

[0002]

2. Description of the Related Art Conventionally, an LCD (liquid crystal display) using a liquid crystal is used.
The spray has been used for so-called pocket TVs and the like, but in recent years, it has been rapidly increasing in size and screen.
In terms of image quality, the development of active drive elements represented by STN liquid crystal and TFT from TN liquid crystal has commercialized those that approach CRT. Although various studies have been conducted to improve the image quality and productivity of color display devices, one of the important technologies is a black matrix for preventing light leakage and improving the image quality (apparent contrast). There is a problem with the so-called light-shielding film forming method and shape. As a method used for forming a lattice-shaped or striped light-shielding coating (black matrix) that fills the portions other than the coating of the color pixels of the color filter used for colorizing LCD, a silk screen method is used. A method using a printing technique such as an offset method is known. Further, a method is known in which a metal thin film such as chromium is formed on a substrate by sputtering or the like, and then a black matrix is formed by photolithography and etching. Recently, a negative resist containing a black pigment has been developed, and a method of forming a black matrix by direct photolithography has been studied. In addition, a strip-shaped color coating film is formed on a plurality of parallel strip-shaped conductive circuits by an electrodeposition method, and then a negative photoresist which provides a light-shielding coating film is coated on the entire surface to form the color coating film. Is used as a mask to expose from the back surface of the substrate to form a light-shielding coating film as a black matrix in the gap between the strip-shaped color coating films (Japanese Patent Laid-Open No. 59-114572, Japanese Patent Laid-Open No. 3145/1982). -42
602).

[0003]

However, recently, in TFT type LCDs, which are promising in the future, it is required to improve the light blocking rate of a light blocking film in order to prevent light leakage of a switching element. Furthermore, in order to improve the image quality, the pattern of the light shielding film has become a lattice shape or other complicated shape. However, in the conventional method, the method of forming the light-shielding coating film by printing can be only a pattern having a gap of about 100 μm between the lattices in the case of a grid pattern, and thus a finer grid-like light-shielding coating film can be formed. Could not be formed accurately. Further, a method of forming a black matrix by direct photolithography using a negative resist containing a black pigment has been studied, but when the light blocking rate becomes high, the photocuring of the resist does not proceed and the black matrix can be formed accurately. It will be difficult. Further, the method of exposing from the back surface of the substrate by using the strip-shaped color coating film formed by the conventional electrodeposition method as a mask can form the light-shielding coating film with high precision between the strip-shaped color coating films. There is a problem that it is difficult to form a light-shielding coating film in a direction that traverses the film.

Therefore, an object of the present invention is to solve the conventional problems as described above, and to form a black matrix having a high light-shielding rate of a fine pattern such as a lattice pattern or a stripe pattern on a substrate with high accuracy. It is to provide a resist, a method for producing a substrate having a black matrix using the photoresist, and a method for producing a color filter using the substrate having the black matrix.

[0005]

Means for Solving the Problems The present inventors have focused their attention on the fact that the transmittance of a certain type of photoresist used in photolithography is lowered during exposure or by subsequent heat treatment, and have conducted earnest studies. The inventors have completed the present invention by finding that the above objects can be achieved. That is, the present invention is as follows. (1) A photoresist for a black matrix, which has a property that the light transmittance of the coating film can be reduced by subjecting the coating film to exposure and / or heat treatment. (2) By subjecting the coating film to exposure and / or heat treatment, the light transmittance of the coating film is adjusted to a visible region (400 to
A photoresist for a black matrix, which has a property that it can be reduced to about 10% or less at 700 nm). (3) The photoresist for black matrix as described in (1) or (2), which contains a novolac resin and a naphthoquinonediazide photosensitizer. (4) A black matrix, wherein the photoresist according to (1), (2) or (3) contains at least one pigment selected from black organic pigments, other organic pigments and inorganic pigments. Photoresist. (5) A black matrix, characterized in that a black matrix is formed on a substrate by a photolithography method using the photoresist for black matrix as described in (1), (2), (3) or (4) above. Of manufacturing a substrate having a. (6) A method for manufacturing a substrate having a black matrix, which comprises sequentially performing the following steps. (A) a step of applying the photoresist according to (1), (2), (3) or (4) above to the surface of the substrate, (b)
An exposure step of irradiating a light beam with a mask having a predetermined pattern superimposed thereon, (c) a development step of removing the intermediate film of an unnecessary portion,
(D) Re-exposing or / and heat treating the developed film to reduce the light transmittance of the coating film, (7) Obtained by the production method described in (5) or (6) above, A method for producing a color filter, which comprises forming a coating film of three primary colors on a pixel portion of a substrate having a black matrix.

The present invention will be described in detail below. The photoresist for black matrix of the present invention also has a property that the light transmittance of the intermediate film is lowered (the light shielding property is increased) by exposure or / and heat treatment. Preferably, the coating film is exposed to light and / or heat-treated to adjust the light transmittance of the coating film to a visible region (400 to 7).
It has a property that it can be reduced to about 10% or less, more preferably about 5% or less at 00 nm).
The thickness of the coating film in this case is about 0.5 to 3 μm. A preferable example is a photoresist containing a cresol novolac resin and a naphthoquinone diazide photosensitive agent. The cresol novolac resin is a resin obtained by condensing cresols and aldehydes. Examples of cresols include m-, p- or o-cresol. Examples of aldehydes include formaldehyde, acetaldehyde, crotonaldehyde, salicylaldehyde and the like. In particular, a resin obtained by condensing p-cresol or a mixture of p-cresol or other cresol or phenol with aldehydes is preferable. The molecular weight of the cresol novolac resin is 3,000 to 1 in terms of polystyrene equivalent weight average molecular weight.
2000 is preferred. In the photoresist, in addition to the resin and the photosensitizer, an organic solvent, and if necessary, a pigment, a crosslinking agent, etc. are added. Examples of the organic solvent include ethers such as dioxane, diethylene glycol dimethyl ether, methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether and ethylene glycol monoisoropyl ether, methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and Ketones such as cyclohexanone, ethyl acetate, butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, esters such as methyl lactate and ethyl lactate, N, N-dimethylformamide and Amides such as N, N-dimethylacetamide, pyro such as N-methylpyrrolidone Pyrrolidones, lactones such as γ-butyrolactone and sulfoxides such as dimethyl sulfoxide and the like. An example of the positive photoresist is PFI-25 (trade name, manufactured by Sumitomo Chemical Co., Ltd.).

In the present invention, the substrate material used to form the black matrix may be a transparent material such as a glass or plastic plate. In addition, after forming a black matrix on the substrate, the method of forming colored layers of R (red), G (green), and B (blue) of the three primary colors on the pixel part is electrodeposition method, pigment dispersion method, printing method. and so on. When the colored layer is formed by the electrodeposition method, a conductive layer or a conductive circuit is required on this substrate. The conductive layer and the conductive circuit are made of a transparent conductive material such as an ITO film (tin-doped indium oxide film) or a Nesa film (antimony-doped tin oxide film). They are,
It is made by a method well known in the art.

In the present invention, as an example, when manufacturing a substrate on which a black matrix having a grid pattern is formed, a schematic view of a cross section of a product obtained in each of the steps (a) to (d) is shown in FIG. It was shown to. Further, FIG. 2 shows a schematic plan view of the lattice-shaped (A) and striped (B) black matrices obtained in the step (d). FIG. 3 shows a structural diagram of a color filter using the obtained lattice-shaped (A) and striped (B) black matrix. In the present invention, the black matrix pattern (plane) may be a lattice pattern, a striped pattern, or any pattern. In the case of a black matrix of a color filter used in a general LCD, the shortest width of the coating film space (pixel portion) is about 200 μm or less. The photoresists and methods of the present invention are particularly effective in forming such black matrices. In the present invention, the shortest width of the space of the coating film refers to the width of the space portion 1 of the coating film as described with reference to FIG.

The step (a) in the present invention is a step of forming a coating film by coating a photoresist providing a black matrix on the entire surface of a transparent substrate having or not having a conductive layer. The photoresist used here has a transmittance that gives sufficient sensitivity at the time of photolithography at this stage, and the transmittance is reduced by the re-exposure or / and heat treatment after the development step, and the light shielding property is exhibited. What is done is used. Examples are mentioned above. When higher light-shielding property is required, the above-mentioned photoresist may be a black organic pigment, other organic pigments such as red, blue, green, violet, cyanine and magenta, and carbon black, titanium black, chromium oxide and the like. It is preferable to add one or more selected from inorganic pigments. The addition amount is preferably about 1 part by weight to 50 parts by weight, but it is not limited to these addition amounts because it depends on the type of pigment, the resist coating method, the sensitivity, and the like.

As a method for forming a photoresist coating film on a substrate, a screen printing method, an offset printing method, a roll coating method, a bar coating method, a spin coating method or the like can be used. Among these, in the case of forming a coating film by the spin coating method, the number of rotations is two steps, and 10
Spread the resist on the substrate at 0-400 rpm, then 800
It is recommended to make the resist film thickness uniform at ~ 5000 rpm. The spin coating method is useful because a coating film can be faithfully and accurately formed on a transparent substrate.
The photoresist applied on the substrate is then heat treated, if necessary, at 60 to 100 ° C. for 5 to 60 minutes. By performing the heat treatment, the resin in the photoresist is pre-cured, and the adhesion between the coating film and the transparent substrate is improved.

In the step (b), when a positive photoresist is used, a mask having a light-shielding pattern for covering a portion where a black matrix is to be formed is superposed on the surface of the formed photoresist coating film, This is an exposure step of irradiating light rays. When using a negative photoresist, a mask having a light-shielding pattern covering a portion other than the portion where the black matrix is to be formed is overlaid. For the exposure in the step (b), light of various wavelengths can be used depending on the type of the negative or positive type photoresist coating film, but the UV region is generally preferable, and an ultrahigh pressure mercury lamp, a metal halide lamp or the like is used as a light source. The device used can be used. This device is preferably a mirror-type parallel light device for the purpose of patterning accuracy.

In the case of a positive type photoresist coating film, the exposure condition is usually 10 to 500 mJ / cm ² , although it varies depending on the amount of light used and the type of coating film. The exposed portion undergoes a decomposition reaction and becomes soluble in the drug described below. In the case of a negative type photoresist coating film, the exposure amount is usually 10 to 500 mJ / cm ^{2, although} it depends on the amount of light used and the type of coating film. The portion not exposed to light is not hardened and becomes soluble in the drug described later.

The step (c) is a developing step for removing the coating film existing in the portion other than the portion where the black matrix is to be formed. In the case of a positive photoresist coating, the exposed parts of the coating are dissolved and removed. The removal can be performed by contacting with a drug (developing solution) having an appropriate dissolving power. Various kinds of such agents are selected depending on the type of positive photoresist coating film.
Usually, an alkaline aqueous solution obtained by dissolving caustic soda, sodium carbonate, a quaternary ammonium salt and an organic amine in water, or an organic solvent of ester, ketone, alcohol, aromatic hydrocarbon or chlorinated hydrocarbon Select and use as appropriate. The removal can be performed by dipping or showering in about 5 seconds to 3 minutes. After that, the remaining coating film is thoroughly washed with water, pure water or the like.

In the case of a negative type photoresist coating film, the unexposed portion of the coating film is removed as an uncured portion.
The removal can be performed in the same manner as in the case of the positive photoresist coating film described above. By this step, a black matrix made of a negative or positive photoresist coating film is formed according to the pattern shape of the mask. Examples of the pattern of the coating film formed here include A and B of FIG.

In step (d), the positive or negative photoresist coating film formed in step (c) is reexposed or /
And a step of heat treatment. This re-exposure and / or heat treatment lowers the transmittance of the photoresist coating film and imparts light-shielding properties. Re-exposure can be omitted when sufficient light-shielding property can be obtained only by heat treatment. The heat treatment is necessary in most cases in order to improve the adhesion of the resist coating film to the substrate and the strength of the coating film itself. The re-exposure condition is that the UV exposure amount is 50 to 1000 mJ / c.
m ² is preferable, and the heat treatment condition is a temperature of 150 to 300.
℃, time 15 minutes to 5 hours is preferable, especially temperature 2
More preferably, it is about 0 to 250 ° C. and about 1 to 2 hours. Through the above steps, a black matrix having a fine pattern such as a lattice pattern or a stripe pattern is formed.

In the case of producing a color filter for LCD or the like, after the black matrix coating film is formed on the transparent substrate by using the method of the present invention, a usual electrodeposition coating method, pigment dispersion method or A coating film of three primary colors (red, green, blue) is formed in a predetermined arrangement by a printing method. In the case of the electrodeposition coating method, a transparent substrate having a transparent conductive film layer or a transparent conductive film circuit pattern formed on the surface is used. After forming the three primary colors, an overcoat film (protective film) is formed thereon. As the overcoat material, epoxy, polyimide, acrylate-based resin or the like is used. The overcoat film is formed by applying a resin with a spin coater, a roll coater, or the like and then thermally curing the resin. Then, a transparent conductive film is further formed thereon for use as a liquid crystal drive electrode, and a circuit pattern is formed if necessary, thus completing the color filter.

The present invention will be described in detail below with reference to examples.

【Example】

(1) Formation of photoresist coating: Positive photoresist (trade name PFI-25, cresol novolac obtained by condensing p-cresol, m-cresol, and formaldehyde on the entire transparent substrate and o-naphthoquinone diazide 5-sulfonic acid ester) Contains as a main component,
(Sumitomo Chemical Co., Ltd.) coating by spin coating 2
00 rpm / 5 seconds, 1000 rpm / 20 seconds in order, and heat-treated in an oven at 60 ° C for 30 minutes to obtain a film thickness of 1.
A 5 μm positive type photoresist coating film was formed. (Above (a) process)

(2) Exposure A pattern mask patterned in a grid pattern (opening: 60 μm × 200 μm) is set on the positive type photoresist coating film (gap: 30 μm), and the proximity using an ultrahigh pressure mercury lamp as a light source is set. Exposure machine (Dainippon Kaken MAP-1
200) and the exposure amount was 100 mJ / cm ² . (Above (b) step)

(3) Development After exposure, the substrate is immersed in a developing solution (trade name SOPD, manufactured by Sumitomo Chemical Co., Ltd., temperature: 25 ° C.) for 60 seconds for development, the exposed portion is removed, rinsed with pure water and air blow drying. Thus, a positive photoresist film was formed on the window portion of the lattice. (Above (c) process)

(4) Heat Treatment The substrate having the positive photoresist coating film on the window portion of the lattice obtained in the above step (c) was heat treated in an oven at 250 ° C. for 2 hours. [Step (d) above] As a result, a grid-like light-shielding coating film (black matrix, film thickness 1.2 μm) conforming to the shape of the pattern mask used in step (b) was formed on the transparent substrate. Apply this light-shielding coating to an optical microscope (Nikon Corporation, trade name OPTIPHOT-8
Observing with 8) at a magnification of 200 times, a grid-like light-shielding coating film was accurately formed. The light transmittance of the light-shielding coating film in the visible region was 5% or less.

[0021]

When the photoresist of the present invention is used, L
It is possible to easily manufacture a substrate used for manufacturing a CD color filter, on which a light-shielding coating film (black matrix) having a fine pattern such as a lattice shape or a stripe shape is accurately formed. In particular, it is possible to manufacture a substrate on which a fine light-shielding coating film pattern is precisely formed such that the shortest width of the pattern coating film space (pixel portion) is about 200 μm or less.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a product or the like obtained in each step of the present invention.

FIG. 2 is a schematic plan view of a light-shielding coating film (black matrix) obtained in step (d) in the present invention.
Figure (a) shows for TFT, and (b) shows for STN.

FIG. 3 is a structural diagram of a color filter using a substrate having a light-shielding coating film (black matrix) obtained in the present invention. Figure (a) is for TFT and b) is for STN.

[Explanation of symbols]

 1. Transparent substrate 2. Photoresist coating 3. Ray 4. Photomask (transparent part) 5. Photomask (light-shielding part) 6. Light-shielding coating film (black matrix) 7. Colored pixel 8. Overcoat 9. Transparent conductive film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeki Yamamoto 3-1,98 Kasugadeka, Konohana-ku, Osaka Sumitomo Chemical Co., Ltd.

Claims (7)

[Claims] 1. A photoresist for a black matrix, which has a property that the light transmittance of the coating film can be reduced by subjecting the coating film to exposure and / or heat treatment. 2. The coating film is exposed to light and / or heat-treated so that the light transmittance of the coating film is in the visible region (4).
A photoresist for a black matrix, which has a property that it can be reduced to about 10% or less at (00 to 700 nm). 3. A novolak-based resin and a naphthoquinonediazide-based photosensitizer are contained.
The photoresist for black matrix described in 1. 4. A photoresist for a black matrix, wherein the photoresist according to claim 1, 2 or 3 contains at least one pigment selected from a black organic pigment, other organic pigments and inorganic pigments. . 5. A substrate having a black matrix, characterized in that a black matrix is formed on the substrate by a photolithography method using the photoresist for a black matrix according to claim 1, 2, 3 or 4. Method. 6. A method for manufacturing a substrate having a black matrix, which comprises sequentially performing the following steps. (A) a step of applying the photoresist according to claim 1, 2, 3 or 4 on a substrate surface, (b) an exposure step of irradiating a light beam with a mask having a predetermined pattern superimposed thereon, (c) an unnecessary portion And (d) a step of reducing the light transmittance of the coating film by re-exposing or / and heat treating the developed film. 7. A method of manufacturing a color filter, comprising forming a coating film of three primary colors on a pixel portion of a substrate having a black matrix, which is obtained by the manufacturing method according to claim 5.