JPH04100021A - Production of electrode substrate for liquid crystal display - Google Patents

Abstract

PURPOSE:To obscure defect picture elements in a normally white display by forming color filters on an active matrix substrate by a wet electrolysis method and further using the color filters as an exposing mask. CONSTITUTION:A pigment film R is first electrolytically formed by energizing a prescribed Ta line electrode. In succession, the pigment films are formed in order of G and B by selectively energizing prescribed Ta line electrodes by the similar operations. A transparent acrylic resin film is then formed over the entire surface formed with these pigment films to for the protective film for the pigment films. A black negative resist is in succession applied on this acrylic resin film by spin coating to attain a film thickness. The black resist film, i.e. the black matrix as a light shielding film is formed in all the parts of the pigment film forming parts and the MIM element forming parts and exclusive of the Ta/Ta2O5 line parts by development. Finally, the panel is formed by using a TN type liquid crystal. The color images of the high contrast with the inconspicuous defects are obtd. when the normally white display state is checked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an electrode substrate used in a liquid crystal display.

[Prior Art] Active matrix color liquid crystal panels used in liquid crystal televisions and the like often employ normally white display with a good color tone of -4. That is, a white display is performed when no voltage is applied to the liquid crystal, and a black display is performed when a voltage is applied to the liquid crystal.

However, in this normally white display, if a predetermined voltage is not applied to a specific pixel electrode due to a defect in the active matrix element, etc., the liquid crystal of that pixel is always in an OFF state, and the light is constantly transmitted through the pixel. Therefore, in a display state with a dark tone, point defects become very noticeable, resulting in poor appearance.

On the other hand, it is an unavoidable problem that defects occur in several places out of about 100,000 pixels due to the influence of dust etc. in the manufacturing process, but it is a defect that is only discovered after the LCD panel is manufactured. , it was extremely difficult to find out before panel assembly. Therefore, it has been nearly impossible to take measures to make the defects less noticeable as point defects, such as by selectively providing a light-shielding film on the defective pixels in advance.

Conventionally, for example, in our MIM active matrix panels, point defects such as those mentioned above were mainly caused by C of MIM elements.
Disconnection of the r electrode often occurs in at least several pixels in one screen, and when performing normally white display with good color tone, even if it is only a few pixels out of around 100,000 pixels, This has been a problem as it is a visually noticeable defect.

[Problem to be Solved by the Invention] As mentioned above, in conventional active matrix color liquid crystal panels such as liquid crystal color televisions, the above-mentioned point defects occur in normally white display, which poses problems in terms of image quality. . Therefore, an object of the present invention is to provide a method for selectively forming a light-shielding film on defective pixel electrodes on an active matrix element substrate before panel assembly, so that the occurrence of pixel defects is limited to only a few locations. The key to the level panel is to make it less noticeable and improve the image quality of the panel.

[Means for Solving the Problems] The method for manufacturing an electrode substrate for a liquid crystal display of the present invention includes, as a first step, forming a pigment film having predetermined spectral characteristics on a pixel transparent electrode in a transparent substrate on which an active matrix element is formed. After forming by a wet electrolytic method, as a second step, a black negative resist having light-shielding properties is applied on the surface on which the active matrix element and the pigment film are formed, and is exposed to light from the back side of the coated surface to form a black resist. It is characterized by forming a matrix.

The main points of the manufacturing method of the present invention will be summarized and explained below.

A pigment film that will become a color filter layer is formed by wet electrolysis on each pixel transparent electrode of a substrate on which an active matrix element is formed.At this time, electricity is applied to the pixel electrode through the active element to cause electrolysis. is carried out,
A pigment film will not be formed for pixels in which the active element is defective. As a result, pixels with defective elements are detected.

Next, a black negative resist is applied to the entire surface and exposed to light from the back side. At this time, the color filter layer made of a pigment film acts as a mask that absorbs the photosensitive wavelength of the negative resist during exposure. . On the other hand, since the wiring on the active matrix substrate also plays the role of a mask to block light during exposure, all defective pixel areas detected on the substrate and gaps between pixel electrodes and wiring are covered with black. Instead, a black resist layer is formed in a self-aligned manner. Therefore, when a liquid crystal panel is formed, defective pixels do not transmit light, making them less noticeable, and since visible light does not pass through anything other than the color filter layer, high contrast can be easily ensured.

Furthermore, the method for forming a color filter using a pigment film of the present invention is a method that we have already proposed in JP-A-2-24603; A pigment film is formed by performing electrolysis in a micellar water droplet liquid, and pigment films of three primary colors, R, G, and B, can be formed. Also, this electrolysis is usually +0.3~0.5V (V,,S,C,E)
(7) Since this is possible at a low potential, even if the substrate on which the active element is formed is used as an anode electrode for film formation, at least the metal in contact with the electrolyte in the active element is zero.
．． Since the pigment film can be maintained at a potential of 5 V or less, its dissolution is extremely difficult to occur.The color filter layer made of a pigment film formed by this method can normally obtain sufficient spectral characteristics with a film thickness of 10 μm or less.

Normally, when performing a normally white display, if there is a layer other than the liquid crystal and alignment film (for example, a color filter layer) between the upper and lower substrates of the liquid crystal panel, voltage loss due to that layer will occur, so the liquid crystal will not stand up sufficiently. It disappears. Therefore, a black color with sufficiently low transmittance cannot be obtained, and as a result, high contrast cannot be obtained. In the case of the present invention, since a color filter layer is formed on the pixel electrode of the active matrix substrate, a color filter layer is present between the counter substrate and the liquid crystal in addition to the liquid crystal and the alignment film. Since the filter layer has a thin film thickness of 1 μm or less as described above, the loss of applied voltage is extremely low, which has the great advantage of not interfering with normally white display.

[Example] Ta/Ta20 on a 26-inch diagonal glass substrate
230 x 330 M
A transparent pixel electrode made of ITO was also formed on the IM element. A pixel plan view and a cross-sectional view are shown in FIGS. 1a and 1b. T
The film thickness of a is 3000 mm, and the Ta formed on it
x Os is formed by anodic oxidation of Ta and has a film thickness of 600 nm. Furthermore, C with a film thickness of 1500 people on Ta2e5
r to Ta/ Ta 20. A predetermined pattern was formed so as to intersect with the laminated pattern. The area of intersection is 5×
It was set to 4 μm. This intersection functions as an MIM element. The transparent pixel electrode made of ITO was processed into a predetermined pattern so as to make electrical contact only with the Cr of the MIL element.

Next, an organic pigment film was formed on the ITO pixel electrode of this substrate by electrolysis. Electrolysis is performed using a Ta line electrode (3 in Figure 1 a)
For the pixel electrode connected to that line,
This was done by applying current through each MIM element. At this time, the active matrix substrate is used as an anode,
A PT board was used as the calid. The Ta line electrode selectively energized a predetermined line among a large number of lines to electrolyze it. That is, organic pigment films of the same color are formed on all the pixel electrodes arranged on the energized line electrodes, and organic pigment films of the three primary colors R, G, and H are formed continuously every two lines. Ta lines were selected so as to be arranged repeatedly, and electrolytic film formation was performed three times in total. Note that the Ta line is Ta
Although it has a structure in which 205 is laminated, Ta is exposed at the current-carrying part at the end so that electrical contact can be easily made. The electrolytic conditions are described below. Table 1 shows the composition of the electrolytic solution used to form each of the R, G, and H pigment films.

Table 1 *1 Ferrocenyl PEG (manufactured by Doguchi Kagaku) *2 LiBr electrolyte is prepared by dissolving a supporting salt in a micellar aqueous solution of a redox-capable surfactant, adding an organic pigment, and then using an ultrasonic homogenizer to remove the organic pigment. It was created by dispersing it and turning it into a colloid. By performing electrolysis in this electrolytic solution, a thin film of organic fine particles can be formed on the substrate used as the anode electrode.

First, an R pigment film was electrolytically formed by applying current to a predetermined Ta line electrode. Electrolysis was performed at 1.5 V (vs, S, C, E), and the amount of current was adjusted so that the film thickness was 08 μm. After the film was formed, it was washed with water and then baked at 200°C for 20 minutes.

Subsequently, a similar operation was performed in the order of G and B to selectively energize predetermined Ta line electrodes to form a film. Each film thickness is 08.07
It was set as μm. By the above operations, R, G, and H color filter layers were formed on the active matrix substrate as shown in FIG. 2.

As a result, no pigment film was formed on 10 pixel electrodes among 230×330 (75,900) pixels. It was found that the cause was mainly due to a disconnection of the Cr pattern of the MIM element. Even if these 10 pixels are made into a liquid crystal panel, liquid crystal driving will not be performed.

Next, a transparent acrylic resin film having a thickness of 02 μm was formed on the entire surface of the substrate on which the pigment film was formed, to serve as a protective film for the pigment film.

Next, a black negative resist (manufactured by Fuji Hunt Technology Co., Ltd.) was coated onto the above-mentioned acrylic resin film to a film thickness of 2. ! It was applied to a thickness of 5 um. After prebaking at 90°C, UV exposure was performed from the full back side of the coated surface using a mercury lamp. At this time, since the pigment film B transmits a part of the wavelength of light to which the resist is sensitive, exposure was performed using a cut filter for that wavelength. By development, a black resist film as a light-shielding film, that is, a black matrix, was formed in all parts except the pigment film formation part, the MIM element formation part, and the Ta/Ta 20s line part. Of course, a black resist film as a black matrix was similarly formed on the pixel electrodes on which no pigment film was formed by electrolysis. This situation is shown in Figure 3.

As a result, all defective pixels whose liquid crystals were not driven were shielded from light by the black resist.

Finally, a panel was constructed using a TN type liquid crystal, and as a result of checking the normally white display state, it was found that defective pixels were hardly noticeable due to the formation of a black resist film, and did not adversely affect the TV image. Therefore, a high-contrast color image with inconspicuous defects was obtained.

[Effect of the invention 1 As described above, according to the present invention, defective pixels are detected by forming a color filter on an active matrix substrate by a wet electrolytic method, and furthermore, by using the color filter as an exposure mask, the color filter layer is Since a black matrix is formed in a self-aligned manner on defective pixels in which no .

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of a part of an active matrix substrate used in an embodiment for explaining the present invention. Transparent pixel electrode 2...MIM element...Ta line electrode FIG. 1(b) is a diagram showing a cross section of the MIM element portion of one pixel of the active matrix substrate used in the embodiment for explaining the present invention. Transparent pixel electrode Cr electrode Ta2'. Ta electrode glass substrate FIG. 2 is a diagram showing a state in which a pigment film (color filter layer) is formed in an example. 1... Pixel electrode on which a pigment film was formed (pixels with diagonal lines) 2... Pixel electrode on which a pigment film was not formed 3...M
IM element FIG. 3 is a diagram showing a state in which a black matrix (black resist film) is formed in an example. Blackmatonnox formed on defective pixels or more

Claims (1)

[Claims] 1) In a transparent substrate on which an active matrix element is formed, a pigment film having predetermined spectral characteristics is formed on a pixel transparent electrode as a first step by a wet electrolytic method, and then as a second step, a light shielding step is performed. 1. An electrode substrate for a liquid crystal display, characterized in that a black negative type resist having a characteristic is coated on the surface on which the active matrix element and the pigment film are formed, and a black matrix is formed by exposing from the back side of the coated surface. Production method. 2) In the method for manufacturing an electrode substrate for a liquid crystal display according to claim 1, the pigment film of the first step is dispersed in a micellar aqueous solution of a surfactant having redox reactivity, and then the pigment is dispersed in the micellar aqueous solution. A method for manufacturing an electrode substrate for a liquid crystal display, characterized in that the transparent substrate on which the active matrix element is formed is immersed as an electrode for electrolysis, and is formed at a predetermined position on the substrate by electrolyzing. 3) The active matrix element according to claim 1 is an MIM.
A method for producing an electrode substrate for a liquid crystal display, characterized in that it is a (metal-insulator-metal) element.