JPH05196969A - Matrix array substrate - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a matrix array substrate in which only the pixel area is expanded at the same pitch as the conventional one and the contrast ratio in a single pixel is improved. [Structure] The matrix array substrate of the present invention is a substrate 11
A plurality of non-linear resistance elements having a three-layer structure of a metal layer-insulator layer-metal layer are formed on the top in an array form, pixel electrodes are arranged in series in each non-linear resistance element, and further, each row is formed by a plurality of wiring electrodes. Alternatively, the above-described object can be achieved by connecting the respective column directions and forming a plurality of wiring electrodes by laminating two adjacent wiring electrodes 13 and 23 with the insulating layer 17 interposed therebetween.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a metal layer-insulator layer-
The present invention relates to a matrix array substrate provided with a non-linear resistance element having a three-layer structure of metal layers as a switching element.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have changed from relatively simple devices such as clocks and calculators to personal computers, word processors, OA terminal devices, TV image displays and the like. It has been used for large capacity display applications.

In this type of liquid crystal display device, conventionally,
It was general to use a multiplex drive system of matrix display, that is, a so-called simple matrix system. However, this method has a drawback that it is not suitable for large-scale matrix display because the contrast ratio between the display portion and the non-display portion deteriorates as the number of scanning lines increases.

Therefore, as one means for solving this drawback, a method of driving each pixel by a switching element, that is, an active matrix method has been developed. In this case, a thin film transistor or a non-linear resistance element is used as the switching element, but a non-linear resistance element which basically has two terminals and has a simple structure is advantageous in terms of manufacturing cost.

Various types of nonlinear resistance elements have been developed. Among them, metal layer-insulator layer-metal layer (M
An element having a three-layer structure (IM) has been put into practical use at present.

Such a MIM type nonlinear resistance element is
Usually, the first metal layer, the second metal layer, and the display pixel electrode are formed by three photolithography steps. The example is shown below.

That is, FIG. 14 is a plan view of two pixels on a conventional matrix array substrate, and FIG.
16C and 16A to 16D are a plan view and a cross-sectional view showing a manufacturing process of a conventional matrix array substrate.
16 (a) to 16 (d) correspond to the line AB of FIG. 15 (a).

Explaining the manufacturing method, first, FIG.
After forming, for example, a Ta film on the glass substrate 1 by a sputtering method as shown in FIGS.
Patterning is performed using the first photolithography process to form the first metal layer (lower electrode) of the nonlinear resistance element.
2 and the wiring electrode 3 integral therewith are formed.

Next, as shown in FIG. 16B, an oxide film is formed on the surfaces of the first metal layer 2 and the wiring electrode 3 by using an anodic oxidation method or the like, and the insulating layer 4 of the nonlinear resistance element is formed. To get Furthermore, after forming, for example, a Ti film on the entire surface by a sputtering method, as shown in FIGS. 15B and 16C, patterning is performed using a second photolithography process to form a nonlinear resistance element. A second metal layer (lower electrode) 5 is formed. Finally, as shown in FIGS. 15C and 16D, ITO (Indium-Tin-Oxide) is used.
After forming a thin film on the entire surface to obtain a transparent electrode, the patterning of the pixel electrode 6 is performed using the third photolithography process, whereby the whole process is completed.

[0010]

[Problems to be Solved by the Invention] Generally, TFD (Thin-Film-
In a (Diode) liquid crystal display device, there is a problem in that the contrast ratio decreases as the number of pixels increases. In order to increase the contrast ratio, structurally, there are conceivable methods such as (1) reducing the area of the light blocking portion and (2) increasing the area of the pixel portion.

In the conventional matrix array substrate, however, in the case of (1), if the wiring electrode 3 which has the greatest influence on the light shielding is made thin, the wiring resistance becomes large and the drive waveform is distorted. As a result, the distribution of contrast and partial unevenness occur, which is not preferable. Also, in terms of process yield, finer processing is performed, which increases the risk of disconnection, which is not preferable. Also in the method (2), increasing the area of the pixel increases the possibility that the pixel portion and the wiring electrode 3 come into contact with each other or the pixel and the pixel, that is, the display defect is caused, and the yield is lowered. Generally, the maximum dimension is usually given in terms of design and process yield, and it is usually difficult to increase the contrast ratio with the conventional structure.

The present invention has been made in order to solve the above problems, and by stacking two wiring electrodes via an insulating layer having a sufficient thickness, a large pixel area and a high contrast ratio can be obtained. It is an object to provide a matrix array substrate.

[0013]

According to the present invention, a plurality of nonlinear resistance elements having a three-layer structure of a metal layer-insulator layer-metal layer are formed in an array on a substrate, and each nonlinear resistance element has a pixel. In a matrix array substrate in which electrodes are arranged in series and each row or column direction is connected by a plurality of wiring electrodes, the plurality of wiring electrodes is a matrix in which two adjacent wiring electrodes are laminated with an insulating layer interposed therebetween. It is an array substrate.

[0014]

According to the present invention, since two adjacent wiring electrodes are laminated with the insulating layer interposed therebetween, the pixel area can be increased by the vacant space and the contrast ratio can be improved. It will be possible. That is, in the prior art, when the contrast ratio in a single pixel is 40, specifically comparing the maximum contrast ratio is 4.8,
In this invention, it can be increased to 5.5.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

The matrix array substrate according to the present invention is constructed as shown in FIG. 1 and represents two pixels. or,
2 to 7 and 8 to 13 are a plan view and a sectional view showing the manufacturing process of the matrix array substrate of the present invention.

That is, to describe the manufacturing method,
First, as shown in FIGS. 2 and 8, a 1.1 mm-thick glass substrate 11 having a SiO ₂ alkali protective coating on the surface thereof.
A first metal layer (lower electrode) 12 of a non-linear resistance element made of Ta having a thickness of 3000 Å and a wiring electrode 13 integrated with the first metal layer 12 are formed as a thin film thereon by a sputtering method. After that, a photoresist (not shown) made of a photosensitive resin is applied over the entire surface of the first metal layer 12 and the wiring electrodes 13, and exposed and developed using a photomask to form a resist pattern.

Next, as the first etching, the thin film is etched by the chemical dry etching method (CDE method), and the etching is performed in the plasma in which the CF ₄ and O ₂ gas ratio is 2: 3. A taper shape is formed on the peripheral portion (edge) of the pattern. After this, the photoresist is removed.

Next, as shown in FIGS. 3 and 9, a photoresist is applied over the entire surface of the glass substrate 11 and the patterned first metal layer 12. Then, the resist pattern 14, which is exposed and developed using a photomask,
Form 15.

Next, as shown in FIG. 4, a resist pattern is formed.
A thin film of Ta ₂ O _5, 16, 17 and 18 having a thickness of 2000 Å is formed on the film 15, the exposed glass substrate 11, the wiring electrode 13 and the resist pattern 14 by the sputtering method. Then 3000 on it
Thin films of angstrom Ta 19, 20, and 21 are formed by a sputtering method.

Here, the resist patterns 14 and 15 are peeled off, and Ta ₂ O ₅ 16 and 18 and Ta 19 and 21 formed on the resist patterns 14 and 15 are removed.
When also removed, it becomes as shown in FIGS.

Next, a photoresist (not shown) made of a photosensitive resin is applied over the entire surface, exposed and developed using a photomask to form a resist pattern. Then, the thin film is etched by the CDE method, but the CF ₄ and O ₂ gas ratio is set to 2: 3. After this etching, if the photoresist is removed, it becomes as shown in FIGS. In this case, reference numeral 22 of Ta20 in the figure becomes the first metal layer (lower electrode) of the nonlinear resistance element different from the above,
Reference numeral 23 is a wiring electrode integrated with this. Therefore, FIG.
As is apparent from the two wiring electrodes 13 and the wiring electrodes 2
3 is laminated through the insulating layer Ta ₂ O ₅ 17, which is a feature of the present invention. That is,
Conventionally, as shown in FIG. 13, two adjacent wiring electrodes 3 and 3 which are separate from each other are stacked and overlapped as described above in the present invention.

In the next step, Ta patterns 12, 13,
Chemical conversion is carried out in an electrolytic solution (0.1 wt% citric acid aqueous solution) using 22 and 23 as anodes and a platinum plate as a cathode. At this time, the anodic oxide film 24 of 700 angstrom was obtained with the formation voltage of 45V.

Next, a film thickness of 150 is formed on the entire surface of the glass substrate 11.
Ti of 0 angstrom is formed by the sputtering method. A photoresist is applied on the entire surface of the Ti film, and the photoresist pattern is exposed and developed to form a resist pattern. Then, 9 g of EDTA (ethylenediamine tetra-acetic acid) and 400 cc of water,
Hydrogen peroxide (216 cc) and ammonia water (30 ml) are mixed together, and the Ti film is etched at room temperature. After that, the resist is removed to form the second metal layer (upper electrode) 25 of the non-linear resistance element as shown in FIGS.

Next, as shown in FIG. 13, ITO is sputtered to form a transparent conductive film 26 having a thickness of 1000 angstrom. Then, a photoresist (not shown) is applied over the entire surface of the thin film, exposed by using a photomask and developed to form a resist pattern. Water here,
Hydrochloric acid and nitric acid are mixed at a ratio of 1: 1: 0.1 (volume ratio), and the transparent conductive film 2 shown in FIG. 13 is formed by etching with an etching solution heated to 30 ° C. and removing the photoresist.
A pattern of 6 is obtained. In this way, the matrix array substrate is completed. A liquid crystal display device is formed using the matrix array substrate as described above, for example, as follows.

First, an alignment film made of polyimide resin is applied to the surface of the matrix array substrate on which the nonlinear resistance element is formed.
The orientation of the liquid crystal is regulated by firing and rubbing (rubbing with a cloth). The same process is performed on the counter substrate, and rubbing is performed in a direction twisted by about 90 ° with respect to one liquid crystal display substrate. Prepare the above two types of substrates, and make sure that the direction of the major axis of the liquid crystal molecules is twisted about 90 ° between the two substrates.
A liquid crystal cell is formed by holding the liquid crystal at a distance of -20 μm and injecting liquid crystal into the space. Then, a polarizing plate is arranged outside the liquid crystal cell with the polarization axis twisted by about 90 °. After that, if a driving circuit is added, the liquid crystal display device is completed.

[0027]

According to the present invention, since two adjacent wiring electrodes are laminated via the insulating layer, only the pixel area can be expanded at the same pitch as the conventional one. That is, the maximum contrast ratio when the contrast ratio of a single pixel is 40 can be improved from 4.8 to 5.5.

[Brief description of drawings]

FIG. 1 is a plan view showing two pixels on a matrix array substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the manufacturing process of the matrix array substrate of the present invention.

FIG. 3 is a cross-sectional view showing another manufacturing process of the matrix array substrate of the present invention.

FIG. 4 is a cross-sectional view showing another manufacturing process of the matrix array substrate of the present invention.

FIG. 5 is a sectional view showing another manufacturing process of the matrix array substrate of the present invention.

FIG. 6 is a sectional view showing another manufacturing process of the matrix array substrate of the present invention.

FIG. 7 is a cross-sectional view showing another manufacturing process of the matrix array substrate of the present invention.

FIG. 8 is a plan view corresponding to FIG.

9 is a plan view corresponding to FIG.

10 is a plan view corresponding to FIG.

11 is a plan view corresponding to FIG.

FIG. 12 is a plan view corresponding to FIG. 7.

FIG. 13 is a cross-sectional view showing another manufacturing process of the matrix array substrate of the present invention.

FIG. 14 is a plan view showing two pixels on a conventional matrix array substrate.

FIG. 15 is a plan view showing a manufacturing process of a conventional matrix array substrate.

FIG. 16 is a sectional view corresponding to FIG. 15, showing a manufacturing process of a conventional matrix array substrate.

[Explanation of symbols]

11 ... Glass substrate, 12 ... First metal layer, 13 ... Wiring electrode, 14, 15 ... Resist pattern, 16, 17, 18
... Ta ₂ O ₅ (insulating layer), 19, 20, 21 ... Ta, 2
2 ... 1st metal layer, 23 ... Wiring electrode, 24 ... Anodized film, 25 ... 2nd metal layer, 26 ... Transparent conductive film.

Claims (1)

[Claims] 1. A metal layer-insulator layer-metal layer on a substrate.
A matrix array substrate in which a plurality of nonlinear resistance elements having a layered structure is formed in an array, pixel electrodes are arranged in series in each nonlinear resistance element, and each row or column direction is connected by a plurality of wiring electrodes, A matrix array substrate, wherein a plurality of wiring electrodes are formed by laminating two adjacent wiring electrodes via an insulating layer.