JPH063506B2 - Transparent substrate for color liquid crystal display - Google Patents

Description

The present invention relates to a transparent substrate for color liquid crystal display suitable for use in a liquid crystal display device capable of color display.

[Conventional technology]

Liquid crystal displays are currently used in many display devices such as various measuring devices and information processing devices. Currently, it is most commonly used in flat panel displays because it consumes less power and can be made lighter and smaller. However, the display quality has not always been excellent. In recent years, the technological progress of liquid crystal display has been remarkable, and the quality has been improved from the conventional monochrome display to the color display type.

For color liquid crystal displays, the method of using a micro color filter is considered to be the most effective method for both full-color and multi-color displays. As a micro color filter, one that uses a filter dyed with gelatin or casein with a dye, one that forms colored pixels by a photolithographic method using a pre-colored organic resin, and ink that incorporates a pigment is formed on a transparent glass substrate by printing. Several types of color filters for color liquid crystal displays, such as those produced by the method, have been proposed and put into practical use.

Further, a transparent electrode is provided on the glass substrate on which the color filter is formed, and the size of the display screen is provided on the electrode.
Fine patterning is required depending on the definition. As a glass substrate for performing color liquid crystal display, a patterned transparent electrode is formed on the glass substrate, and a color filter formed of colored pixels is formed on the electrode.
In some cases, a color filter having desired colored pixels is formed on a glass substrate, and a transparent conductive layer is formed on the color filter.

The latter is superior in display quality because the net driving voltage is applied to the liquid crystal and there is no loss due to the color filter layer. Therefore, in a color liquid crystal display, a color filter to be a colored pixel is first provided on a glass substrate, an organic protective layer is provided on the glass substrate for planarization, and a single transparent conductive layer is provided thereon. A glass substrate for color liquid crystal display is used as a color display with high display quality.

In recent years, the color liquid crystal display screen has become larger and the demand for higher quality display has increased, and the size of the colored pixels has become smaller and smaller. Therefore, linear ITO (tin-doped indium oxide) provided on the colored pixels
The line width of the transparent electrode must be narrowed. Since the voltage drop due to the line resistance of the transparent electrode is not preferable for driving the liquid crystal, the transparent electrode needs to have a low resistance value such that the voltage drop does not become an obstacle. Therefore, a low-resistance transparent conductive layer has become indispensable for realizing a large-scale, high-definition display. On the other hand, it is well known that a single ITO film, which has been widely used as a material having the lowest resistivity, is used as a transparent conductive layer. The ITO film is manufactured by any of the sputtering method, the vapor deposition method and the dipping method. To obtain a low resistivity film, the glass substrate should be heated to a high temperature of 300 ° C. or higher for deposition. It is necessary to go through a so-called high temperature process such as heat treatment at a high temperature of 300 ° C. or higher after forming a film on the substrate at room temperature.

[Problems to be Solved by the Invention]

As described above, the multicolored colored pixels used for the color liquid crystal display all use an organic substance as a base material, and since the coloring material itself is a dye or an organic pigment, heat deterioration occurs at high temperatures. A high temperature process cannot be adopted for forming the ITO film. For this reason, the formation of the ITO film is about 20 due to the restrictions on the heat resistance strength of the colored pixel.
The upper limit temperature is 0 ° C., and it is necessary to form a film by a low temperature process below this temperature. However, the resistivity of the ITO film depends on the process temperature (substrate heating temperature during film formation and heat treatment temperature after film formation).
Has the property of increasing as Since the resistance value of the ITO single film by the low temperature process is large,
When a transparent conductive layer having a small sheet resistance is required, the film thickness becomes very large. If the film thickness is large, the patterning of fine electrodes required for high-definition display becomes extremely disadvantageous. That is, it is difficult to ensure the dimensional accuracy of the pattern due to the occurrence of the side-etching phenomenon, and it is difficult to perform uniform etching completely.Therefore, defects such as short-circuiting due to poor electrode insulation between electrodes due to uneven etching are likely to occur and electrode patterning is It becomes difficult to perform with good yield. Further, when the thickness of the ITO film is increased, the internal stress of the film is increased, and there is a drawback that wrinkles are generated in the underlying protective film and the colored body, which causes a fatal defect in display quality. Further, the internal stress of the film has a risk that it partially impairs the adhesiveness to the base material and adversely affects the reliability of the liquid crystal display device.

[Means for Solving the Problems]

The present invention is to solve the problems of the glass substrate with a color filter that has been conventionally used, and an object of the present invention is to provide a color having a transparent conductive layer having a low resistance and easy fine patterning of the conductive film. It is to provide a glass substrate for a liquid crystal display.

That is, the present invention is a color liquid crystal display substrate comprising a transparent substrate, a color filter layer formed on the surface of the transparent substrate to be a colored pixel, and a transparent conductive layer provided on the color filter layer, The transparent conductive layer comprises, from the color filter layer side, a first layer of a metal oxide layer, a second layer of an acid-soluble metal or an alloy layer of the metal, and a third layer of an acid-soluble metal oxide layer. A glass substrate for a color liquid crystal display, which has a three-layer structure.

In the present invention, the color filter layer to be a colored pixel is formed by patterning gelatin or segaine in a predetermined size and coloring it with a dye, or a pre-colored photosensitive or non-photosensitive acrylic or polyimide resin is photolithographically processed. It is manufactured by various materials and manufacturing methods, such as those subjected to patterning with, or those obtained by kneading an organic resin with a colorant containing an organic pigment as a main component and printing the mixture to a predetermined size by an offset printing method.

And, the present invention is usually provided between the color filter layer and the transparent conductive layer a transparent organic protective layer such as polyimide, polyamide, acrylic and epoxy resin for flattening the surface of the color filter layer. Is. Further, in the present invention, silver, copper, or an alloy thereof is used as the second layer of the transparent conductive layer. Silver alloy,
Titanium, chromium, and tin are used as the metal forming the copper alloy, and the content of these components is usually preferably 10% or less in order not to lower the transmittance and to improve the corrosion resistance.

In the present invention, the first conductive metal oxide layer of the transparent conductive layer is an electrically insulating metal oxide or an electrically conductive metal that is the same as the third conductive layer and can be removed by etching simultaneously with the second conductive layer metal or alloy. It may be a layer metal oxide. As the electrically insulating oxide, it is possible to use one that is transparent, has good adhesion to the base, and has various refractive indices. For example, TiO ₂ , ZrO ₂ , HfO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , Bi ₂ O ₃ , and SiO ₂ are used. In addition, In ₂ O is used as the electrically conductive metal oxide.
In ₂ O ₃ doped with ₃ or Sn can be used.

Furthermore, the third metal oxide layer of the transparent conductive layer is usually
In ₂ O ₃ doped with In ₂ O ₃ and Sn are used.

Therefore, as the transparent conductive layer in the present invention, the first layer /
As the second layer / third layer, SiO ₂ / Ag / ITO, Al ₂ O ₃ / Ag / ITO, TiO
₂ / Ag / ITO, ZrO ₂ / Ag / ITO, SiO ₂ / Ag / In ₂ O ₃ , SiO ₂ / Cu / ITO, Al ₂
O ₃ / Cu / ITO, TiO ₂ / Cu / ITO, HfO ₂ / Cu / In ₂ O ₃ , ITO / Ag / ITO, ITO
It is preferable to use / Cu / ITO.

The thickness of each of the first layer and the third layer of the transparent conductive film is usually in the range of about 100 to 400Å, and the second layer of the transparent conductive film is usually used in the range of 100 to 200Å. , The total thickness of the transparent conductive film is 300 to 1000Å
It is usually used in the range of.

[Action]

The present invention uses a transparent conductive layer provided on a color filter layer to be a colored pixel and sandwiches a metal or a metal alloy with a metal oxide layer to provide a thin transparent conductive layer having an area resistance of 10Ω / At the same time that a low Sq is obtained, by making the outermost metal oxide layer of the transparent conductive layer acid-soluble, the metal or metal alloy of the transparent conductive layer is formed into a predetermined pattern in a relatively short time. Can be etched with acid.

Further, according to the present invention, by selecting the thickness and type (refractive index) of each of the three layers forming the transparent conductive layer, the optical interference effect
The transmittance of the transparent substrate for color liquid crystal display can be increased.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

2 parts by weight of Lake Red C (red dispersant manufactured by Dainippon Kasei Co., Ltd.) is mixed with 10 parts by weight of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 90 mol%, and a colorant in a supernatant portion of the resulting mixture. 3 parts by weight and an average degree of polymerization of 500 saponification degree of 9
Photosensitive resin composition (A) in which 6 mol% of P-formyltythryl pyridine is added to 0 mol% of polyvinyl alcohol
Was adjusted. Next, this solution was added to 100 mm × 100 mm × 1.
After coating with a spinner to a film thickness of about 1 μm on a 0 mm glass substrate (1), drying for 30 minutes, and then performing pattern exposure through a mask, and then selectively removing the unexposed portion with isopropyl alcohol After heating at 160 ° C. for 30 minutes, a dot-shaped filter layer (3) shown in red (R) was formed. Similarly, a green photosensitive resin composition (B) containing Lionol Green 2Y-301 (a green pigment manufactured by Toyo Ink Mfg. Co., Ltd.) as a coloring component, and Fast Gemble-GNPS.
A blue photosensitive resin composition (C) containing (Dai Nippon Ink Chemical Co., Ltd. blue pigment) as a coloring component is prepared to give a red (R) color.
Similarly to the filter layer (3), dot-like green (G) filter layers (3) and blue (B) filter layers (3) were prepared to form the color filter layer (3) shown in FIG.

Next, in order to flatten the surface of the filter layer (3), spin a 1.5 μm thick arlyl resin (Nippon Synthetic Rubber Co., Ltd., trade name Optomer SS) so as to cover the color filter layer (3) part. The protective layer (4) was formed by coating. A transparent conductive film (2) was formed on the resin protective layer (4). The transparent conductive layer (2) comprises a first metal oxide layer (5), a metal layer (6) and a metal oxide layer (7). For the metal oxide layer (5), three kinds of SiO ₂ , Al ₂ O ₃ and TiO ₂ were selected and respective samples were prepared. That is, the SiO ₂ layer (5) is deposited to a predetermined thickness by high frequency magnetron sputtering in an argon atmosphere, and the Al ₂ O ₃ layer (5) and the TiO ₂ layer (5) are formed by using respective metal targets. And a predetermined thickness by direct current reactive sputtering in a mixed gas atmosphere of oxygen and oxygen.

Next, Ag or Cu was selected for the metal layer (6), and a metal target was deposited on the metal oxide layer (5) to a predetermined thickness by direct current sputtering in an argon gas atmosphere. Further, the metal oxide layer (7) is DC-sputtered in a mixed gas atmosphere of argon and a small amount of oxygen with an ITO sintered body containing SnO ₂ of 10 wt% as a target, and the ITO layer (7) having a predetermined thickness is formed into a metal. Deposited on layer (5). The glass plate (1) was not particularly heated during the formation of the metal oxide layers (5), (7) and the metal layer (6),
When forming the metal layer (6), the glass plate (1) may be heated within a range in which particle growth does not develop and aggregate into particles.

On the other hand, as a comparative example, while heating the glass plate (1) on which the color filter layer (3), the resin protective layer (4), and the SiO ₂ layer of 150 Å are sequentially heated to 180 ° C., a small amount of argon gas and An ITO film having a film thickness of 3900Å was formed on the SiO ₂ layer by a sputtering method in a mixed gas atmosphere with oxygen.

With respect to the transparent conductive layer (2) of the transparent substrate for color liquid crystal display obtained as described above, the electrode patterning property, the durability evaluation by the cold and warm cycle test, the sheet resistance and the light transmittance were examined. The results are shown in Table 1. Samples 1 to 5 were etched with 1N hydrochloric acid at 40 ° C. for 4 to 5 minutes using a predetermined mask pattern and a masking resist. Sample 6 (Comparative Example) could not be etched at this concentration. Unnecessary portions were etched at 45 ° C in 5N hydrochloric acid for 8 to 10 minutes.

Samples 1 to 5 have a sheet resistance of semi-transparent Ag in the middle layer.
Due to the effect of the film or Cu film, the transmittance was as low as 10Ω / Sq or less and at the same time as high as 70% or more at a wavelength of 550 μm, and it was possible to perform a clear patterning of the edge shape with dilute hydrochloric acid in a short time. . By the photolithographic method using a commonly used photoresist and mask, parallel stripe-shaped transparent electrode patterns having an electrode line width of 50 μm and an interelectrode space of 10 μm were possible in Samples 1 to 5. (However, the first layer of Samples 1 to 4 is not etched.) However, Sample 6 (comparative example)
Then, the sheet resistance is 10 Ω / Sq or less, but the film thickness must be made thicker than the value of the specific resistance of the film (4 times or more of that of the present invention). Therefore, pattern etching with hydrochloric acid causes side etching, resulting in thinning. Or, meandering occurred, the electrode patterning property was poor, and fine processing was difficult.

As shown in Table 3, the glass substrate for color liquid crystal display (1) having the stripe-shaped transparent electrode (2) extending in the direction perpendicular to the above-mentioned paper surface, and the other glass having the ITO stripe-shaped transparent electrode (9) Liquid crystal filled in the space formed by the substrate (8) and the sealing material (10) provided around them
A color liquid crystal display element composed of (11) and is produced.

〔The invention's effect〕

As described above, the present invention uses a transparent conductive layer provided on a color filter layer to be a colored pixel and sandwiching a metal or a metal alloy with a metal oxide layer to provide an area of a thin transparent conductive layer. Since a material having low resistance can be obtained, side etching does not occur, thinning and meandering do not occur, and fine pattern processing can be performed.

Moreover, according to the present invention, by selecting the thickness and the refractive index of each of the three layers constituting the transparent conductive layer, the transmittance of the color liquid crystal display transparent substrate can be increased by the optical interference effect.

Therefore, the color liquid crystal display device of the present invention has a large screen and is suitable for use in a color liquid crystal display device having high definition and high brightness.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a sectional view of a glass substrate for color liquid crystal display, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a glass substrate for color liquid crystal display. FIG. 6 is a cross-sectional view of an RGB liquid crystal display element using. 1, 8: glass plate, 2: transparent conductive layer, 3: color filter layer, 4: resin protective layer, 5: first metal oxide layer,
6: metal or alloy layer, 7: third metal oxide layer, 9:
Transparent electrode, 10: sealing material, 11: liquid crystal.

Claims (6)

[Claims] 1. A color liquid crystal display substrate comprising a transparent substrate, a color filter layer formed on the surface of the transparent substrate to serve as colored pixels, and a transparent conductive layer provided on the color filter layer. The transparent conductive layer is a three-layer structure including a first layer of a metal oxide layer, a second layer of an acid-soluble metal or an alloy layer of the metal, and a third layer of an acid-soluble metal oxide layer from the color filter layer side. A transparent substrate for a color liquid crystal display, which has a structure. 2. The color liquid crystal according to claim 1, wherein a transparent organic protective layer for flattening the surface of the color filter layer is provided between the color filter layer and the transparent conductive layer. Display transparent substrate. 3. The second layer of the transparent conductive layer is silver or copper,
Alternatively, the transparent substrate for color liquid crystal display according to claim 1 or 2, which is an alloy layer thereof. 4. The transparent substrate for color liquid crystal display according to claim 1, wherein the first layer of the transparent conductive layer is a conductive and acid-soluble film. 5. The one of claims 1 to 3, wherein the first layer of the transparent conductive layer is electrically insulating.
Transparent substrate for two color LCD displays. 6. The method according to claim 1, wherein the first layer or the third layer of the transparent conductive layer is made of indium oxide or a metal oxide containing indium oxide as a main component. Transparent substrate for two color LCD displays.