JPH04323620A - Color filter - Google Patents

Abstract

PURPOSE:To obtain the color filter which has the transmission characteristics of light uniform over the entire region of visible rays and has the good characteristics of the blue part in particular by forming transparent electrodes of films consisting of zinc oxide or the zinc oxide doped with aluminum. CONSTITUTION:After the inside of a film forming chamber 6 is evacuated to a vacuum, discharge gases consisting of argon and hydrogen are so supplied as to attain a prescribed partial pressure. A magnet 14 which generates spiral motion in the electrons heading toward an anode is provided near a target 12 impressed with a high-frequency voltage. The color filter 2 to be formed with the transparent electrodes is heated to a prescribed temp. in a heating chamber 5 and is then sent to the film forming chamber where the color filter is disposed at the prescribed distance from the target 12 and is formed with the transparent electrodes. After the films are formed to a desired thickness, the color filter is taken out of an unloader chamber 8. The zinc oxide or the zinc oxide mixed with the alumina or the zinc oxide target on which an alumina plate is installed at a prescribed area ratio is used as the target 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter, and more particularly to a color filter for a liquid crystal display device having a transparent electrode film.

0002

[Prior Art] A liquid crystal display device consists of a transparent substrate, such as glass, provided with transparent electrodes, with a gap of approximately several micrometers, and a liquid crystal substance sealed in between.The liquid crystal is oriented in a certain direction by a voltage applied between the electrodes. The image is displayed by aligning the film to form transparent and opaque parts. A color liquid crystal display device displays red (R), which corresponds to the three primary colors of light, on one of the transparent substrates.
It has three color filters: green (G) and blue (B).

[0003] Color filters for color liquid crystal display devices are laminated in this order: a transparent substrate, a colored layer, a protective layer, and a transparent electrode. μm
A liquid crystal display device is formed by filling a liquid crystal material with a gap of .

0004

[Problems to be Solved by the Invention] Color filters are produced by pigment dispersion, dyeing, electrodeposition, etc. on a transparent substrate such as glass.
A colored layer with the three primary colors of R, G, and B in a predetermined shape is formed by a printing method, a protective layer is formed on the colored layer for the purpose of protecting the colored layer, and a liquid crystal layer is further formed on the protective layer. A transparent electrode for driving is formed.

[0005] Tin oxide, indium oxide, and a composite oxide thereof called ITO are used for the transparent electrode. There are various methods for forming transparent electrodes, such as vapor deposition, ion plating, and sputtering. However, since the protective film that forms the base of the transparent electrode of the color filter is made of synthetic resin, the heat resistance of the protective film is limited. In view of this, there is a need for a method that allows film formation at relatively low temperatures. For this reason, sputtering is widely used to manufacture transparent electrodes for color filters.

It is known that thin films such as ITO films produced by thin film forming methods such as vapor deposition and sputtering have different properties depending on the film forming conditions.

[0007] ITO films used as transparent electrodes for color filters are required to have various properties.
Among these, the light transmission characteristics and the thermal stability of the ITO film, which affect the characteristics of the color liquid crystal display device, are important factors.

FIG. 2(B) shows an example of the light transmission characteristics of an ITO film, which was formed under the conventional film forming conditions of argon pressure of 3 x 10-3 torr. However, single wavelength light, especially blue light (λ=450 nm)
This shows that the absorption in the vicinity is large. therefore,
A color filter having an ITO film has a problem in obtaining a natural color image because of a decrease in blue transmittance.

[0009] Furthermore, since the ITO film has poor thermal stability, when exposed to high temperatures of 200°C or higher during the color filter manufacturing process, the specific resistance of the film may increase or the transmittance may change. there were.

0010

[Means for Solving the Problems] The present inventors have investigated means for solving the above-mentioned problems, and have developed a collar in which a transparent electrode made of zinc oxide or zinc oxide doped with alumina is formed instead of the ITO film. It was discovered that the filter also has good light transmission properties, and the properties of the transparent electrode are not adversely affected by the temperatures exposed in the color filter manufacturing process.

That is, the transparent electrode of the color filter of the present invention is formed by forming a protective film on a colored layer formed on a glass substrate, and forming a film on the protective film by sputtering, particularly by high frequency magnetron sputtering method. By forming a film using a zinc oxide target or a zinc oxide mixed with alumina as a doping agent as a target, it is possible to produce a transparent electrode film with low resistivity and excellent properties as a transparent electrode.

The sputtering conditions for the transparent electrode film are hydrogen partial pressure of 1×10-5 torr to 4×10-5 torr.
The pressure set to r is 6 x 10-4 torr to 4 x 10-2 t.
The discharge gas is a mixed gas of argon and hydrogen, but the temperature of the substrate on which the transparent electrode is formed affects the specific resistance of the transparent electrode to be formed, and the lower the substrate temperature, the lower the specific resistance. Lower substrate temperatures are preferred because smaller films can be obtained.

[0013] Even if the substrate is not particularly heated, the temperature naturally rises during sputtering and is heated to several tens of degrees Celsius, but a film with sufficiently low resistivity can be obtained at this temperature.

[0014] Furthermore, the transparent electrode made of zinc oxide used in the present invention has excellent properties in terms of etching properties and thermal stability.

[0015]

[Operation] The present invention provides a color filter in which a transparent electrode is provided on a protective film provided on a colored layer formed on a substrate, in which the transparent electrode is a transparent thin film of zinc oxide or zinc oxide doped with alumina. Thus, a color filter can be obtained that has good visible light transmission characteristics and can display a color image with excellent color characteristics.

Examples of the present invention will be shown below and explained in more detail.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained with reference to the drawings. FIG. 1 shows an example of a sputtering apparatus for manufacturing the color filter of the present invention. The sputtering apparatus 1 includes a load chamber 3 into which a color filter 2 for forming a transparent electrode is introduced, a transport device 4 for transporting the color filter, a heating chamber 5 for heating the color filter to a predetermined temperature, and a structure for forming a transparent electrode by sputtering. It consists of a film chamber 6, a cooling chamber 7 for cooling the temperature of the substrate, and an unloading chamber 8 for taking out the substrate.

The loading chamber, the film forming chamber, and the unloading chamber are connected to exhaust devices 9, 10, and 11, respectively, and the film forming chamber 6
After sufficiently evacuating with a vacuum pump, a discharge gas consisting of argon and hydrogen is supplied to a predetermined partial pressure, and an anode 13 is placed near the target 12 to which a high frequency voltage is applied, and the discharge of the target is performed. A magnet 14 is provided on the opposite surface to cause a spiral movement in the electrons heading toward the anode.

Color filter 2 on which transparent electrodes are to be formed
After being heated to a predetermined temperature in the heating chamber 5, it is sent to the film forming chamber and placed at a predetermined distance from the target to form a transparent electrode, and after forming a film of the desired thickness, it is sent from the unloading chamber. Take it out.

[0020] The target may be a zinc oxide target mixed with zinc oxide or alumina, or a zinc oxide target with an alumina plate set at an area ratio of 1 to 10%.

Example 1 A glass substrate (AL material manufactured by Asahi Glass Co., Ltd.) with a size of 300 mm x 320 mm and a thickness of 1.1 mm was thoroughly cleaned, and a red photosensitive resin was applied on it to a thickness of 1 to 2 μm. The film was then dried in an oven for 30 minutes at a temperature of 70°C, exposed using a mercury lamp, and spray developed with water for 1 minute to create a red relief in the area where the red pixels were to be formed. Form an image and further heat at 150°C for 30 minutes.
Cured by heating.

The same process was repeated to form a green relief pixel in the area where the green pixel was to be formed, and a blue relief pixel in the area where the blue pixel was to be formed, thereby forming a colored layer.

Next, as a photocurable acrylate oligomer, bisphenol A acrylate (molecular weight 1500
~2000), 50 parts by weight of trimethylolpropane triacrylate (TMPTA manufactured by Nippon Kayaku) as a polyfunctional polymerizable monomer, and 2 parts by weight of Irgacure 651 (manufactured by Ciba Geigy) as a polymerization initiator. The formulation was treated with ethylcellosolve acetate 20
0 parts by weight, and 10 g of the solution was applied onto the colored layer to a thickness of 2.0 μm using a spin coater. A photomask is placed in contact with the coating film, and 2.0kW is applied.
Ultra-high-pressure mercury lamps are used to emit ultraviolet rays only on the colored layer.
Irradiated for 0 seconds. Next, 1, 1, 2 at a temperature of 25°C.
It was immersed in a developer consisting of 2-tetrachloroethane for 1 minute to remove only the uncured portion of the coating film.

Next, the substrate on which the obtained protective film has been formed is placed in a sputtering device, and after the pressure is reduced to 10-6 torr, a mixed gas of argon and hydrogen is added to the sputtering device so that the hydrogen partial pressure becomes 4×10-5 torr. ×10-4torr~2
The film was introduced into the film forming chamber at a pressure of x10-2 torr.

A high frequency power of 13.56 MHz and 1.5 kW was supplied between the target and the substrate holder of the sputtering apparatus, and the distance between the target and the substrate was 80 mm.
Sputtering was performed for 40 minutes to form a transparent electrode with a thickness of 0.24 μm.

The specific resistance of the obtained transparent electrode was 9×10−4
Ω・cm, and the light transmission characteristics of this transparent electrode are shown in Figure 2 (
As shown in A), it has almost uniform characteristics over the entire visible light range, and the transmittance in the blue region (λ = 450 nm), which is particularly important in terms of the color characteristics of color filters, is 91% to 92%. The blue part of the ITO film shown in 2(B) (λ=450
This was excellent compared to the transmittance of 88% at 100 nm).

[0027]

[Effect of the invention] In a color filter used in a color display device using liquid crystal, the transparent electrode formed on the substrate coated with an organic substance is formed of a film made of zinc oxide or zinc oxide doped with aluminum. Since the light transmission characteristics are uniform over the entire visible light range, a color filter with good color characteristics can be obtained, and the zinc oxide used for the transparent electrode is ITO.
Since it is an inexpensive material with sufficient resources compared to membrane materials, it also has the secondary effect of lower manufacturing costs.

[Brief explanation of drawings]

FIG. 1 shows an example of a sputtering apparatus for producing a color filter of the present invention.

FIG. 2 shows the permeation characteristics of an ITO film and a zinc oxide film.

[Explanation of symbols]

1... Sputtering device, 2... Color filter, 3...
Loading chamber, 4...Transporting device, 5...Heating chamber, 6...Film forming chamber, 7
...Cooling chamber, 8...Unloading chamber, 9, 10, 11...Exhaust device, 12...Target, 13...Anode, 14...Magnet, 15
…High voltage power supply

Claims (1)

[Claims] Claim 1: A color filter in which a transparent electrode is provided on a protective film provided on a colored layer formed on a substrate,
A color filter characterized in that the transparent electrode is made of zinc oxide or zinc oxide doped with alumina. 1. The color filter according to claim 1, wherein the transparent electrode is formed by sputtering using zinc oxide or zinc oxide containing alumina as a target.