JPH0713147A - Color filter substrate and liquid crystal display element - Google Patents

Abstract

PURPOSE:To improve adhesion strength of a conductive film on a color filter substrate having a transparent electrode and to improve fine processing characteristics (patterning characteristics) of the conductive film by using a silicon oxide film containing carbon as an intermediate film. CONSTITUTION:A color filter 2 comprising a resin with dispersion of a pigment is formed to 5mum thickness on a transparent glass substrate 1 by printing, and further, a resin protective layer 3 is formed by applying an acryl resin to 3mum thickness by a roll coating method. After a mixture gas (Ar/O2) is introduced and its flow amt. is controlled to obtain 3X10<-3>Torr pressure, a silicon oxide film containing carbon is formed to 100nm thickness as an intermediate film 5 by a DC magnetron sputtering method using a SiC target at 200 deg.C substrate temp. Further, a transparent conductive film 4 of ITO is formed to 250nm thickness by a magnetron sputtering method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter substrate for use in a color display device and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art The basic structure of a color filter substrate with a transparent conductive film used in a conventional color liquid crystal display device comprises a transparent substrate / color filter layer / resin protective layer / conductive film.

The conductive film is mainly used as a transparent electrode of a liquid crystal display element. For the conductive film, a transparent conductive metal oxide thin film typified by a tin-doped indium oxide (ITO) thin film is formed on the color filter by a PVD method such as a sputtering method or a vacuum deposition method, and then a photolithography process is performed. -Generally, fine processing (patterning) is performed through a wet etching process. In this case, a resin protective layer is often provided between the color filter and the conductive film for the purpose of protecting the color filter from heat and chemicals such as acid used in the transparent electrode processing step.

[0004]

However, depending on the composition of the resin protective layer and the film forming conditions of the conductive film, sufficient adhesion of the resin protective layer / conductive film cannot be obtained, and peeling may occur during patterning of the conductive film. However, there is a problem in that the stability of patterning is affected by the occurrence of undercuts and side etching. Further, as one of the conventional methods, a system using SiO ₂ as an intermediate film in which carbon is not positively introduced is known, but the problem is that the rf sputtering method, which is relatively difficult to control, must be used. However, there are problems such as insufficient adhesion between the resin protective layer and the conventional SiO ₂ intermediate layer in which carbon is not positively introduced.

[0005]

The present invention has been made to solve the above problems, and provides a color filter substrate having a structure in which a color filter layer, a resin protective layer, and a conductive film are laminated on a substrate. The present invention provides a color filter substrate having an intermediate film containing carbon-containing silicon oxide as a main component between a resin protective layer and a conductive film, and a liquid crystal display device using the same.

FIG. 1 is a cross section of a color filter substrate of the present invention. 1 is a transparent substrate, 2 is a color filter layer,
3 is a resin protective layer, 4 is a conductive film to be patterned,
Reference numeral 5 is an intermediate film containing silicon oxide containing carbon as a main component.

In the present invention, the conductive film 4 and the resin protective layer 3
As a typical preferable example of the intermediate film 5 provided for improving the adhesive force, a film containing carbon-containing silicon oxide as a main component is given, but other metal oxides containing carbon may be used. ZrO ₂ , TiO containing carbon
₂ and Al ₂ O ₃ are typical examples.

The present invention, as described in claims 3, 4, and 5, uses a vacuum evaporation method or a sputtering method as an evaporation source,
It can be produced by selecting the composition of the reaction gas and the target and combining them. The manufacturing method by DC magnetron sputtering is considered to be the most preferable in view of advantages such as ease of control and uniformity of film quality, but the present invention is not limited to this method.

Specifically, it is produced by an EB vapor deposition method using a mixture of silicon oxide and silicon carbide as a vapor deposition source.
EB using silicon carbide as a vapor deposition source and oxygen as a reaction gas
Using a vapor deposition method, using silicon oxide as a vapor deposition source, and using at least one of carbon dioxide and methane as a reaction gas, targeting silicon carbide and using oxygen, carbon dioxide, and methane as a reaction gas. Using at least one or more of the above, using a target containing at least one or more of silicon, silicon oxide, and silicon carbide, and using at least one of oxygen and carbon dioxide as a reaction gas, For example, using a sputtering method.

The thickness of the intermediate film 5 is 5 nm to 50 nm, preferably 10 nm to 30 nm. If the thickness is less than 5 nm, sufficient adhesion between the resin protective layer 3 and the transparent substrate 1 cannot be obtained, and the effect as an intermediate film cannot be exhibited. Also, 50
If it is thicker than nm, the internal stress of the intermediate film becomes large, and cracks may occur in the intermediate film 5, which is not suitable.

The carbon content in the intermediate film 5 may be determined in consideration of optical characteristics (refractive index, etc.), mechanical / chemical durability, etc., but the atomic ratio is 1 to 20%. It is desirable to contain the above carbon. The amount of carbon in the intermediate film 5 is E
It can be measured by SCA. An interlayer film containing 1% or less of carbon may not exert the effect of the present invention,
The intermediate film containing 20% or more of carbon may have a reduced surface insulation resistance, and carbon may be taken into a conductive film such as ITO, which may impair the electrical characteristics of the conductive film.

The color filter layer 2 of the present invention is not particularly limited, and may be one made of gelatin or the like by a dyeing method, one by an electrodeposition method, or one in which a pigment is dispersed in a resin such as a polyimide resin or an acrylic resin.

The pattern of the color filter layer 2 is not particularly limited, and for example, a stripe pattern,
Either a mosaic pattern or a delta pattern may be used. Further, in order to improve the contrast, a light-shielding pattern such as a black matrix may be formed between the patterns, and the black matrix may be formed by depositing a metal film of chromium or the like by a vapor deposition method, a sputtering method, or the like, or a black The photosensitive resist may be patterned by photolithography.

Examples of the material of the resin protective layer 3 of the present invention include various resins such as acrylic resins, epoxy resins, polyimide resins, and silicone resins, but are not particularly limited. The resin protective layer 3 is applied onto the color filter layer 2 by a spin coating method, a roll coating method, a dipping method, or a spraying method, and its film thickness is generally 1 to 10 μm, but is not particularly limited. .

The method for producing a color filter substrate according to the present invention will be described below by taking as an example the case where a color filter layer using a colored resist in which a pigment is dispersed in a resin and an acrylic resin protective layer are adopted.

First, a light shielding layer called a black matrix is formed on a transparent substrate such as glass or plastic.
This light-shielding layer is provided in the TFT type liquid crystal element in order to maintain the characteristics of the transistor or prevent the deterioration of the contrast ratio, and is usually formed of a thin metal film such as chromium having excellent light-shielding properties.

In the simple matrix drive represented by the STN (Super Twisted Nematic) system, the contrast of the device is originally lower than that of the TFT system, and the black matrix is required because of the demand for cost reduction. It is often omitted, formed by superimposing three primary colors, or formed of a single color resist.

Next, a colored resist containing a dye such as a pigment and a photosensitive resin is applied on the substrate, and a PVA (polyvinyl alcohol) layer or the like as an oxygen barrier film is applied on the colored resist, and then the predetermined resist is applied. Exposure is performed through the photomask having the pattern shape, and then the unexposed portion is removed by development to form a color pattern. This operation is repeated twice with another color to form a color filter of three primary colors.

On top of this, an acrylic resin is added to the resin protective layer 3
To form. As a forming method, it is general to apply by a spin coating method, a roll coating method, a dipping method, and then cure in a clean oven or a hot plate, but another method may be used.

Next, the silicon oxide containing carbon is formed as an intermediate film 5 on the resin protective layer 3. The manufacturing method is a sputtering method or a vacuum deposition method using at least one of silicon, silicon oxide and silicon carbide as a raw material and using either oxygen or methane as a reaction gas. The intermediate film 5 can also be patterned at the time of film formation.

Next, a conductive film (electrode layer) is formed on the protective film.
4 is formed. The transmissive display needs to be light transmissive, and in particular, tin-doped indium oxide (IT
A typical example is a thin film of O) or tin oxide, zinc oxide doped with F, Al, and Sb, but other metal compound thin films may be used. When it is not used as a transmissive display, it does not necessarily need to be transparent, and aluminum or chromium may be used in some cases.

The conductive film 4 is preferably patterned according to the display, but when it is used as a common electrode, it may be an electrode used without patterning. As a method of forming the conductive film 4 (not particularly limited to this), a vacuum vapor deposition method, a magnetron sputtering method, or the like is preferably used from the viewpoint of making the film thickness uniform.

In the present invention, TFTs, MIMs, active elements such as thin film diodes, retardation films, polarizing films, reflection films, photoconductive films, etc. are formed above or below the electrodes as required. Good.

Further, in the case of a liquid crystal display, an alignment film is formed on the electrode-attached substrate as needed. This may be obtained by rubbing an organic resin film of polyimide, polyamide, polyvinyl alcohol or the like, obliquely vapor-deposited SiO _x or the like, or applied with a vertical alignment agent.

Further, as a method for producing a liquid crystal display, a method which is usually used can be adopted. That is, one of the pair of substrates is the color filter substrate, the other is an appropriately patterned substrate with electrodes,
A liquid crystal alignment film is formed on the substrates as needed, and then the pair of substrates are opposed to each other on the electrode surface sides and the peripheral portions are sealed to enclose the liquid crystal therein. This makes it possible to obtain a liquid crystal display having high definition.

Applications of the color filter substrate of the present invention include a liquid crystal display surface, a cathode ray tube display surface, and a light receiving surface of an image pickup tube. In particular, since a color filter having a relatively small thickness unevenness can be obtained, it is preferable as a liquid crystal element in which the accuracy of the space between substrates is strictly required.

[0027]

Function The mechanism of action of improving the patterning characteristics by providing an intermediate film of SiO ₂ containing carbon is not always clear, but the main component SiO ₂ has a chemical affinity with the conductive film 4 which is a metal oxide film. It is considered that the effect of improving the chemical resistance and improving the chemical affinity of the contained carbon with the resin protective layer 3 which is an organic substance results in the improvement of the adhesive force between the resin protective layer 3 and the conductive film 4. There is. That is, in the color filter substrate, the carbon-containing Si of the present invention is used.
The O ₂ intermediate film has an excellent feature that it leads to better patterning characteristics as compared with the conventional SiO ₂ intermediate film containing no carbon.

[0028]

【Example】

(Example 1) A color filter made of a resin in which a pigment is dispersed is applied on a transparent glass substrate by a printing method to have a thickness of 5 μm,
Further, an acrylic resin was coated to a thickness of 3 μm as the resin protective layer 3 by a roll coater method. On top of that, SiC
After using a target and introducing a mixed gas (Ar / O ₂ ) and adjusting the flow rate so that the pressure is 3 × 10 ⁻³ Torr, the substrate temperature is 200 ° C. and the film thickness is 1 by DC magnetron sputtering.
A silicon oxide film containing carbon and having a thickness of 00 nm was formed as the intermediate film 5. The film composition of the produced intermediate film was as shown in Table 1. The film composition was measured by ESCA.

[0029]

[Table 1]

Further, a transparent conductive film made of ITO having a thickness of 250 nm was formed thereon by a magnetron sputtering method.

After a line-shaped resist (masking agent) is formed on the ITO film, it is immersed in a hydrochloric acid / ferric chloride-based etching solution (etchant) to perform fine processing (patterning) of the ITO film. It was As a result, the side etching amount of the ITO film on the intermediate film (SE amount: the amount by which etching progressed further than the width of the resist and became thinner) was as shown in Table 3.

In Comparative Example 1, the ITO film was directly formed on the resin protective layer without forming the intermediate film. Comparative example 2
Was prepared by carbon-free silicon oxide as an intermediate film by rf sputtering using SiO ₂ as a target, and similarly to Example 1, an ITO thin film was formed on the intermediate film and patterned. It is a thing.

(Example 2) The same color filter substrate with a resin protective film as in Example 1 was set in a vacuum chamber and mixed gas (Ar: 82%, O ₂ : 3%, CH ₃ : 15%) was added. Introduce and pressure 3 × 1
The temperature was adjusted to 0 ^-3 Torr, a SiO ₂ target was used, the substrate temperature was 200 ° C., and rf magnetron sputtering was performed to obtain
A silicon oxide film containing carbon of nm was formed as an intermediate film. The film composition of the produced intermediate film was as shown in Table 2.

[0034]

[Table 2]

As in the first embodiment, ITO is formed on the intermediate film 5.
A thin film was formed and patterned. as a result,
The amount of side etching of the ITO film on the intermediate film was as shown in Table 3.

In Examples 1 and 2, the amount of side etching of the ITO film when the ITO film was patterned was very small and good. Further, the sheet resistance of the ITO film of the example is 9 to 10 Ω / □, and IT formed on the glass substrate.
The value was almost the same as that of the O film, and almost no increase in the specific resistance of the ITO film due to the intermediate film was observed.

The color filter-attached electrode substrates obtained in Examples 1 and 2 were used as one substrate, and the other electrode-attached substrate was used to form an alignment film obtained by rubbing a polyimide film on the surface. did. A liquid crystal ZLI2293 (trade name, manufactured by Merck & Co., Inc.) containing a chiral compound was used as the liquid crystal, and the liquid crystal was sandwiched between the substrates to prepare a 240 ° twisted 1/240 duty liquid crystal display device. When this liquid crystal display device was driven, it was confirmed that there was little in-plane color difference, good contrast and color reproducibility, and high-quality full-color display was possible.

[0038]

[Table 3]

[0039]

INDUSTRIAL APPLICABILITY The present invention has an excellent effect that the adhesive force of the conductive film is improved and the fine processing property (patterning property) of the conductive film is improved in the color filter substrate with the transparent electrode, and especially the side etching is performed. There is an effect that various problems such as undercut are solved.

Further, while the conventional carbon-free silicon oxide film has to use the rf sputtering method, the carbon-containing silicon oxide film of the present invention can be formed by the DC magnetron sputtering method. It is also advantageous in that it is large, the film quality is uniform, and the process is simplified.

Further, the adoption of the protective film has an advantage that the specific resistance value of the conductive film typified by ITO can be made as low as that of the transparent conductive film when it is formed on the glass substrate.

[Brief description of drawings]

FIG. 1 is a sectional view of a color filter substrate according to the present invention.

[Explanation of symbols]

 1: transparent substrate 2: color filter layer 3: resin protective layer 4: conductive film 5: intermediate film

Claims (4)

[Claims] 1. A color filter substrate having a structure in which a color filter layer, a resin protective layer, and a conductive film are laminated on a substrate, and a main component is silicon oxide containing carbon between the resin protective layer and the conductive film. A color filter substrate having an intermediate film of 2. The carbon content of the intermediate layer is such that the atomic ratio (C / Si + O +
The color filter substrate according to claim 1, wherein C) is 1 to 20%. 3. The color filter substrate according to claim 1 or 2, wherein the intermediate film has a thickness of 5 to 50 nm. 4. A liquid crystal display device comprising the color filter substrate according to claim 1 as at least one of a pair of substrates, and a liquid crystal layer sandwiched between the pair of substrates.