JPH04352104A - Production of color filter - Google Patents

Abstract

PURPOSE:To produce a color filter using a thermosetting substance as the material of the protective coat while preventing the chipping, exfoliation and defective adhesion of the transparent electrode. CONSTITUTION:A protective coat 4 made of a cured film of a thermosetting substance is formed on a transparent substrate 3 with plural image elements made of colorant layers having different colors and an electric conductive transparent film 5a is formed on the protective coat 4 to produce a color filter. At this time, the protective coat 4 is formed at a higher temp. than the electric conductive transparent film 5a.

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 provided with transparent electrodes, such as a color filter for liquid crystal color displays.

0002

[Prior Art] Color filters for flat displays such as liquid crystal, electroluminescence, and plasma type displays include at least (1) a plurality of pixel portions each consisting of a colored layer and (2) a transparent electrode driven as a signal electrode on a transparent substrate. It will be established. In such a color filter, pixel portions are provided on a transparent substrate in a predetermined arrangement such as a mosaic shape or a stripe shape. On the other hand, although the transparent electrode may be provided directly on the top surface of the pixel section, it is generally provided on a protective film formed on the top surface of the pixel section or on a protective film formed to cover the pixel section. established in

Among color filters equipped with transparent electrodes, for example, a color filter in which a transparent electrode is provided on a protective film formed to cover a pixel portion is manufactured as follows. be exposed. First, a plurality of pixel portions are provided in a predetermined array on a transparent substrate such as glass by a method such as printing, electrodeposition, or dyeing, and these pixel portions are coated with S.
Inorganic transparent substances such as iO2, TiO2, glass,
Acrylic resin, epoxy resin, silicone resin,
Cover with a protective film made of a transparent organic material such as polyimide resin. Protective films made of SiO2 or TiO2 are formed by sputtering or vacuum evaporation, and protective films made of organic transparent materials are coated with these substances or their solutions by spin coating, etc., and then hardened by heat treatment at a predetermined temperature. A film is formed by A protective film made of glass is formed by applying a sol solution used when obtaining glass by the sol-gel method by spin coating or the like, and then hardening (vitrifying) it by heat treatment at a predetermined temperature. Next, I
Using a transparent electrode material such as TO, SnO2, In2O3, etc., a transparent conductive film made of the transparent electrode material is formed on the protective film by sputtering, vacuum evaporation, or the like. Thereafter, a color filter is obtained by forming a transparent electrode in a shape corresponding to the arrangement pattern of the pixel portion by etching the transparent conductive film using a predetermined mask. Here, when a film of the inorganic transparent material is formed as a protective film by sputtering method or vacuum evaporation method,
In terms of workability and productivity, this method is inferior to the case where a thermosetting material such as the organic transparent material or the sol solution is used. Therefore, a thermosetting substance is preferably used as the material for the protective film.

0004

[Problems to be Solved by the Invention] However, in conventional color filters that use a thermosetting substance as a material for the protective film, the transparent electrode obtained by molding the transparent conductive film into a predetermined shape has problems such as chipping, peeling, etc. There is a problem in that the electrical properties of the transparent electrode and the optical properties of the color filter tend to be insufficient due to poor adhesion. Therefore, an object of the present invention is to provide a method for manufacturing a color filter, which can manufacture a color filter using a thermosetting substance as a protective film material while preventing chipping, peeling, poor adhesion, etc. of transparent electrodes. It's about doing.

[0005]

[Means for Solving the Problems] As a result of intensive research into the causes of cracking, peeling, poor adhesion, etc. of transparent electrodes in color filters obtained by conventional manufacturing methods, the inventors have determined that the causes are transparent conductive A critical interface between the protective film and the conductive film may occur due to the generation of gas from the protective film during film formation or the progression of the curing reaction of the protective film during film formation, resulting in volumetric contraction or expansion of the protective film. As a result of discovering that wrinkles, undulations, voids, etc. are caused by the formation of wrinkles, undulations, voids, etc., and researching means to prevent these, the present invention was completed. That is, the present invention that achieves the above object includes a step of forming a protective film made of a cured film of a thermosetting substance on a transparent substrate provided with a plurality of pixel portions made of colored layers of different colors; When manufacturing a color filter by a method including a step of forming a transparent conductive film on a protective film, the film forming temperature T1 of the protective film and the film forming temperature T2 of the transparent conductive film are set as follows.
It is characterized by being selected so as to satisfy the following relational expression T1≧T2.

[0006] The film forming temperature T1 of the protective film as used in the present invention means the processing temperature for curing the thermosetting substance that is the material of the protective film to form a cured film. For example, when a thermosetting resin is used as the protective film material, it means the heat treatment temperature for curing the thermosetting resin. In addition, if a photocurable resin is used as the protective film material and heat treatment is performed to further increase the film hardness after photocuring the photocurable resin, the heat treatment applied to further increase the film hardness temperature.

On the other hand, the film forming temperature T2 of a transparent conductive film in the present invention refers to a transparent conductive film (a film that becomes a transparent electrode by patterning) having desired optical properties (light transmittance) and electrical properties. ) means the highest temperature in the process for forming a film on the protective film. For example, when forming an ITO film as a transparent conductive film by vacuum evaporation method, the following a.
or b. a When obtaining an ITO film with desired optical and electrical properties without thermal oxidation treatment, the substrate temperature during film formation. b When obtaining an ITO film with desired optical and electrical properties by performing thermal oxidation treatment after film formation, the temperature of the substrate at the time of film formation or the temperature at the time of thermal oxidation treatment, whichever is higher. .

[0008]

[Function] By setting the protective film forming temperature T1 to a temperature higher than the transparent conductive film forming temperature T2, gas generation from the protective film during forming the transparent conductive film and Further curing of the protective film is inhibited. That is, the occurrence of wrinkles, undulations, voids, etc. at the critical interface between the protective film and the conductive film is suppressed. Therefore, according to the method of the present invention, it is possible to prevent the deterioration of the electrical properties and optical properties of the transparent electrode that would otherwise occur due to the formation of the transparent electrode on the protective film.

[0009]

EXAMPLES The present invention will be explained in more detail below based on examples and with reference to the drawings, but the method of the present invention is not limited to the methods of these examples. Example 1 A chromium (Cr) thin film with a predetermined pattern was provided as a light shielding layer on one surface of a transparent substrate made of aluminosilicate glass.
An acrylic negative resist in which phthalocyanine green (trade name: SAX, manufactured by Sanyo Shiki Co., Ltd.) is dispersed is applied to the surface of the transparent substrate on the side where the thin film is provided to form a colored layer, and then this colored layer is formed using a photolithography method. A dispersed pixel portion (green color) was formed by forming a predetermined pattern into a mosaic shape. After this, phthalocyanine blue (product name: SR
1500, manufactured by Sanyo Shiki Co., Ltd.) and an acrylic negative resist in which an azo red pigment (trade name: Red Pigment FB Carmine, manufactured by Sumitomo Chemical Co., Ltd.) was dispersed, the green pixel area was A blue pixel portion and a red pixel portion are sequentially formed in a predetermined mosaic pattern in the same manner as in the formation of
(thin film) 1, an aluminosilicate glass transparent substrate 3 on which a red pixel portion 2R, a green pixel portion 2G, and a blue pixel portion 2B were provided in a mosaic pattern was obtained. Next, the pixel parts 2R, 2G, 2B on the transparent substrate 3 obtained above were heated to 200°C (
= T3 ), then the light shielding film 1 and the pixel part 2R are
, 2G, and 2B are provided on the surface of the transparent substrate 3 by spin coating for about 2.5 hours with an overcoat agent (trade name: Optomer SS-7215, manufactured by Japan Synthetic Rubber Co., Ltd.) containing acrylic resin as the main component. The coating was applied to a thickness of 5 μm (thickness from the surface of the transparent substrate 3; the same applies to the following examples). After sufficiently drying this overcoat agent at room temperature, heat treatment was performed at 200°C (=T1) for 1 hour in a conventional oven to harden the overcoat agent.
As shown in the figure, a protective film 4 was formed on the surface of the transparent substrate 3 on the side where the light shielding film 1 and the pixel parts 2R, 2G, and 2B were provided.

Next, by vacuum evaporation method, the substrate temperature was 180°C.
(=T2), and as shown in FIG. 3, a transparent conductive film (ITO film) 5a having a thickness of 1400 angstroms was provided on the protective film 4. When the surface of this transparent conductive film 5a was traced with a stylus-type surface roughness meter to check the state of the ridges, no wrinkles or undulations were observed. Further, when observed under an optical microscope, no cracks, chips, or falling off were observed, indicating that the film was in good condition. From this observation result, it can be seen that there are no wrinkles, undulations, or poor adhesion at the critical surface between the protective film 4 and the transparent conductive film 5a. Next, a photoresist (product name: A
A photoresist layer 6a was formed on the transparent conductive film 5a as shown in FIG. The photoresist layer 6a was exposed using a predetermined mask and developed to form a resist pattern 6b on the transparent conductive film 5a, as shown in FIG. After that, the resist pattern 6b was post-baked at 120° C. for 30 minutes, and then a mixture of 40 Baume degree ferric chloride and hydrochloric acid was prepared.
The transparent conductive film 5a was etched by immersing it in a mixed solution of 1 (solution temperature: 50° C.) to form a transparent electrode 5b in a predetermined pattern as shown in FIG. Next, the resist pattern 6b was peeled off using an organic solvent (methylcellulosolve acetate) to obtain a color filter 7 in which the transparent electrode 5b was provided on the protective film 4.

The width of the transparent electrode 5b in the color filter 7 thus obtained is the same as that of the resist pattern 6b.
The line width was 99 μm compared to 100 μm of the predetermined mask used in forming the mask, and no disconnections or undulations due to chips, burrs, cracks, etc. were observed. Further, the sheet resistance of the transparent electrode 5b was 23Ω/□. color filter 7
The film forming temperature of the protective film 4 (=T1), the film forming temperature of the transparent conductive film 5a (=T2), the transmittance of the protective film 4 after forming the transparent conductive film 5a, the transmittance of the transparent conductive film 5a, The presence or absence of undulations in the conductive film 5a, the surface roughness of the transparent conductive film 5a, the sheet resistance of the transparent electrode 5b, and the presence or absence of chipping, peeling, or poor adhesion in the transparent electrode 5b (hereinafter these are collectively referred to as various characteristics of the color filter). It is shown in Table 1.

Examples 2 to 9 and Comparative Examples 1 to 6 Color filters were formed in the same manner as in Example 1, except that the film formation temperature of the protective film and the film formation temperature of the transparent conductive film were set to the temperatures shown in Table 1. Obtained. Table 1 shows the characteristics of each color filter.

Example 10 An organic-inorganic composite overcoat agent (trade name: JHR-3040, manufactured by Japan Synthetic Rubber Co., Ltd., which corresponds to a sol solution when glass is obtained by the sol-gel method) was used as the material for the protective film. This overcoat agent was spin-coated to a thickness of 3.8 μm, and the film-forming temperature T1 of the protective film was 220°C, and the film-forming temperature T2 (substrate temperature) of the transparent conductive film (ITO film) was 220°C.
A color filter having a transparent electrode provided on the protective film was obtained in the same manner as in Example 1 except that the temperature was 00°C. Table 1 shows various properties of the obtained color filter.

Example 11 A photocurable acrylic copolymer (trade name: RFG-7, manufactured by Sekisui Fine Chemical Co., Ltd.) was used as the material for the protective film, and this copolymer was applied to a thickness of 1.5 μm. After curing with ultraviolet rays, a protective film was formed by further curing by heat treatment at 220°C (=T1) for 30 minutes, and the film formation temperature T2 (substrate temperature) of the transparent conductive film (ITO film) was set to 190°C. A color filter having a transparent electrode provided on the protective film was obtained in the same manner as in Example 1 except that the temperature was changed to .degree. Table 1 shows the characteristics of each color filter obtained.

Example 12 Polyimide resin (trade name: PSI) was used as the material for the protective film.
A transparent conductive film (IT
A color filter having a transparent electrode provided on the protective film was obtained in the same manner as in Example 1 except that the film formation temperature T2 (substrate temperature) of the O film) was 240°C. Table 1 shows various properties of the obtained color filter.

[0016]

[Table 1]

As is clear from Tables 1 and 2, in Examples 1 to 12 based on the method of the present invention, the transparent conductive film had no undulations, the surface roughness of the transparent conductive film was small, and the transparent electrode had no undulations. Color filters without chipping, peeling, or poor adhesion have been obtained. On the other hand, in Comparative Examples 1 to 6 in which the film formation temperature (=T2) of the transparent conductive film was higher than the film formation temperature (=T1) of the protective film, swelling was observed in the transparent conductive film in all color filters. The surface roughness of the transparent conductive film was large, and chips and peeling were observed on the transparent electrode.

The method of the present invention is not limited to the method of the above-described embodiment, but includes various modifications and applications. For example, as a material for the protective film, if it is a thermosetting material that has a light transmittance when cured that can be used as a protective film, organic polymers such as polyimide resin, polyamide resin, acrylic resin, epoxy resin, etc. Various thermosetting substances can be used, such as organic-inorganic composite materials such as silicon alkoxide (a sol solution used to obtain glass by the sol-gel method). In addition to the ITO used in the examples, the material for the transparent electrode (material for the transparent conductive film) is SnO2, In2O3, and other materials that have the effect of increasing conductivity, such as Te, Se, As, and Sb. A material mixed with a substance may also be used. In both embodiments, the protective film is provided after the pixel portion is heat-treated, but depending on the material and formation method of the pixel portion, the protective film may be provided without this heat treatment. If a solvent or volatile component remains in the pixel portion, these may evaporate during the formation of a protective film or a transparent conductive film. In this case, the protective film prevents the volatilization of solvents and volatile components from the pixel area, which may cause wrinkles and undulations in the pixel area, and wrinkles and undulations in the protective film and transparent conductive film. do. Therefore, whether or not to perform heat treatment on the pixel portion is appropriately selected depending on the material and forming method of the pixel portion. When performing this heat treatment, the heat treatment temperature (=T3
) is preferably carried out at a protective film formation temperature T1 of ±30°C. The method of forming the pixel portion and the pattern thereof are not particularly limited, and the pixel portion can be formed into a known pattern such as a mosaic shape or a stripe shape by a conventional method such as a printing method, an electrodeposition method, or a dyeing method.

The heat treatment for the pixel portion and the heat treatment for curing the protective film material are both aimed at tightening and making the film firm. In the case of a dispersed pixel section in which pigment is dispersed in a photoresist or a protective film material in which a thermosetting substance is dissolved in a solvent, the solvent is usually vaporized after the resist is applied or the protective film material is applied. (For example, in the case of photoresist, heat treatment is performed at around 120°C specified by the manufacturer. It may be performed as a separate process after the heat treatment. However, especially in the case of a thick protective film exceeding 2 μm in thickness, rapid heating may cause the solvent to remain inside the film or cause insufficient curing, resulting in poor adhesion. In this case, it is preferable to perform pre-baking at a normal low temperature and then cure the film at the heat treatment temperature of the present invention. The effect will be better if the rate of temperature increase until reaching this heat treatment temperature is slow.

In the method of the present invention, as described above, the film forming temperature T1 of the protective film and the film forming temperature T1 of the transparent conductive film are
2 and, in some cases, the heat treatment temperature T3 of the pixel part.
stipulates. Here, the upper limit of the film forming temperature T1 of the protective film is not particularly limited, but it goes without saying that the upper limit of T1 is the heat resistance limit of the pixel portion or the heat resistance limit of the material of the protective film. The film-forming temperature T2 of the transparent conductive film is also not particularly limited, but may be any temperature that provides practically sufficient optical properties, electrical properties, and adhesion as a transparent electrode. For example, ITO
In the case of membranes, the temperature is about 100°C or higher, more preferably 150°C.
That's all. Note that in the examples, the substrate temperature during ITO film formation corresponds to T2, but in some cases, thermal oxidation treatment is performed after ITO film formation to improve optical properties and electrical properties, and when NESA is used as a transparent conductive film. When using a film, the higher temperature of the thermal oxidation treatment after film formation and the substrate temperature during film formation is the film formation temperature T of the transparent conductive film in the present invention.
Equivalent to 2. Moreover, the higher the film-forming temperature T1 of the protective film is than the film-forming temperature T2 of the transparent conductive film, the greater the effect of the present invention becomes.

[0021]

[Effects of the Invention] As explained above, according to the present invention,
While preventing chipping, peeling, and poor adhesion of transparent electrodes,
A method for manufacturing a color filter using a thermosetting substance as a material for the protective film has been provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a transparent substrate provided with a plurality of pixel portions made of colored body layers of different colors and a light-shielding layer.

FIG. 2 is a cross-sectional view showing an example of a protective film formed on the transparent substrate shown in FIG. 1;

3 is a cross-sectional view showing an example of a transparent conductive film formed on the protective film shown in FIG. 2. FIG.

FIG. 4 is a cross-sectional view showing an example of a photoresist layer provided for patterning the transparent conductive film shown in FIG. 3 into a transparent electrode.

FIG. 5 is a cross-sectional view showing an example of a resist pattern provided for patterning the transparent conductive film shown in FIG. 4 into a transparent electrode.

6 is a cross-sectional view showing an example of a transparent electrode obtained by patterning a transparent conductive film using the resist pattern shown in FIG. 5. FIG.

FIG. 7 is a sectional view showing an example of a color filter manufactured based on the present invention.

[Explanation of symbols]

2R, 2G, 2B pixel section 3 Transparent substrate 4 Protective film 5a Transparent conductive film 5b Transparent electrode 7 Color filter

Claims (2)

[Claims] 1. A step of forming a protective film made of a cured film of a thermosetting material on a transparent substrate provided with a plurality of pixel portions made of colored body layers of different colors, and forming a transparent conductive film on the protective film. In the method for manufacturing a color filter including the step of forming a film, the film forming temperature T1 of the protective film and the film forming temperature T2 of the transparent conductive film are selected so as to satisfy the following relational expression T1 ≧T2. A method for manufacturing a color filter, characterized by: 2. The method for producing a color filter according to claim 1, which comprises forming a protective film made of a cured film of a thermosetting substance on a transparent substrate provided with a plurality of pixel portions made of a colored layer. Prior to this, the plurality of pixel portions are formed according to the following relational expression T3 ≧T2 with respect to the film forming temperature T2 of the transparent conductive film.
A method for producing a color filter, characterized in that heat treatment is performed at a temperature T3 that satisfies the following.