JPH05232517A - Substrate for liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To provide the substrate for a liquid crystal display device having a black matrix which can completely conceal non-lighting parts without increasing the cost of production. CONSTITUTION:The black matrix 28 formed on a second electrode substrate 12 is formed of the same material as the materials of the first metals 21 and insulators 22 of nonlinear resistance elements 17 formed on the first electrode substrate 11. The same insulators 30 as the insulators 22 forming the nonlinear resistance elements 17 are formed on the surface of the black matrix 28 itself and are, therefore, not shorted to the adjacent parts. The non-lighting parts between picture element electrodes 18 are completely concealed and the contrast is improved. The metals 29 to be the black matrix 28 and the insulators 30 formed on the surface are formed in parallel at the time of forming the first metals 21 and insulators 22 of the nonlinear resistance elements 17 and, therefore, the drastic increase in the cost of the production does not arise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a liquid crystal display device using a metal-insulator-metal element as a switching element and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have changed from relatively simple ones such as clocks, calculators and measuring instruments to personal computers, word processors, terminal equipment for office automation, image display for televisions, etc. Also, it has been widely used for displaying a large amount of information.

In such a large capacity liquid crystal display device, a multiplex drive system of matrix display is generally adopted. However, in this multiplex drive method, as the number of scanning lines increases, the contrast between the display portion, which is an ON pixel, and the non-display portion, which is an OFF pixel, decreases due to the essential characteristics of the liquid crystal itself, so that a large scale is required. Not suitable for matrix display.

In order to solve the problem of the liquid crystal display device, a so-called active matrix system has been developed in which each pixel is directly driven by a switching element. As a switching element in this active matrix system, a thin film transistor (Thin Film Tr
ansistor) and the non-linear resistance element disclosed in Japanese Patent Laid-Open No. 61-32637.

Here, since the non-linear resistance element basically has two terminals as compared with the thin film transistor having three terminals, the structure is simple and the manufacture is easy. For this reason,
The product yield can be expected to be improved, and the cost can be reduced.

Although various types of nonlinear resistance elements have been developed, the so-called MIM element having a metal-insulator-metal (MIM) element structure has been put into practical use. Such a substrate for a liquid crystal display device using an MIM element is disclosed in, for example, JP-A-55-16127.
As disclosed in Japanese Patent Laid-Open No. 3 or Japanese Patent Laid-Open No. 58-178320, it is manufactured as follows.

First, a tantalum (Ta) film is formed on a glass substrate by a thin film forming method such as a sputtering method or a vacuum evaporation method, and a desired signal electrode and an MIM element are formed by using a photolithography technique or the like. Form with metal.

Next, the first metal is formed by an anodizing method (AO method) using an aqueous solution of citric acid or the like to form an insulator. Further, as the other metal electrode of the MIM element, a chromium (Cr) film is formed by a thin film forming method, and this chromium film is used as the second metal to form the MIM element.

A first electrode substrate formed in this way,
By disposing a second electrode substrate having a counter electrode formed in a stripe shape by a transparent conductor such as ITO (Indium Tin Oxide) so as to face each other with a liquid crystal composition interposed therebetween,
A liquid crystal display device is configured.

In the conventional liquid crystal display device, even when the entire display screen is illuminated in black, the region in which neither the pixel electrode for display nor the signal electrode is formed is not in the illuminated state, and is white. Will be displayed. Although this portion is a very small area with respect to the entire display surface, it is generated over the entire surface, so that the display contrast is lowered.

As a means for solving this problem, a so-called black matrix is used to block light in a region of the second electrode substrate facing the first electrode substrate on which the MIM elements are arranged and which faces the non-pixel portion. It has been used to form exposed films. As a material for forming this black matrix, a metal film having a strong light shielding property is used.

Here, in the liquid crystal display device using the above-mentioned MIM element, the second electrode substrate on which the counter electrode is formed usually has a single-layer structure of only an ITO film, so that it is necessary to form a black matrix. , The deposition of the metal thin film layer and the patterning process thereof are added, resulting in an increase in cost.

Further, as a method of forming a metal film different from the ITO film as the counter electrode on the second electrode substrate while suppressing the cost increase to a minimum, Japanese Patent Laid-Open No. 3-31823.
The method described in the publication is known. This method
A first substrate portion including a MIM element and a pixel electrode is formed in one region on a common glass substrate, and a second electrode including a counter electrode and another metal film is formed in the other region of the glass substrate.
The first substrate portion and the second substrate portion are separated at the same time. The separated first electrode substrate and second electrode substrate are opposed to each other as described above, and are assembled as a liquid crystal display device.

According to this method, the other metal film on the second electrode substrate portion can be formed on the first electrode substrate portion at the same time when the first metal is formed. Therefore, if this metal film is used as the black matrix, a large increase in manufacturing cost does not occur because the black matrix is formed.

However, since the black matrix thus formed is a conductive metal film, it must be formed as thin as possible in order to prevent a short circuit with an adjacent portion, and it should be formed between pixel electrodes. Even if it is arranged at the opposite part of FIG.
As shown by, a gap 4 is formed between the pixel electrode 1 which becomes the lighting portion and the wiring electrode 2 and the black matrix 3 which are arranged in the pixel electrode 1, and a non-lighting portion around the pixel electrode 1 is formed. It could not be completely covered, and was insufficient as the black matrix 3.

[0016]

As described above, when the black matrix 3 is formed to increase the contrast, the manufacturing cost increases, and the black matrix 3 is formed without increasing the manufacturing cost. Then, the non-lighted part around the pixel electrode 1 cannot be completely covered, and the black matrix 3 is insufficient.

An object of the present invention is to provide a substrate for a liquid crystal display device having a black matrix capable of almost completely covering a non-lighted portion without increasing the manufacturing cost, and a manufacturing method thereof. ..

[0018]

A liquid crystal display substrate according to claim 1, wherein a plurality of pixel electrodes and a first metal-insulator-second metal electrically connected to each of the pixel electrodes are provided. A first electrode substrate having a non-linear resistance element formed of and a second electrode substrate having a counter electrode facing each pixel electrode of the first electrode substrate can be divided into the same substrate material. In the substrate for a liquid crystal display device formed in step 1, the non-lighted portion between the pixel electrodes on the first electrode substrate on the second electrode substrate on which the counter electrode is formed faces the non-lighted portion. A black matrix having substantially the same shape as the lighting portion is formed of the same material as the first metal-insulator forming the nonlinear resistance element.

According to a second aspect of the present invention, there is provided a method of manufacturing a substrate for a liquid crystal display device, wherein a plurality of pixel electrodes and a first metal-insulator electrically connected to each of the pixel electrodes are provided in one region of the substrate material. Forming a non-linear resistance element made of a second metal to form a portion of the first electrode substrate, and forming a black matrix for the counter electrode and each of the pixel electrodes in the other region of the substrate material. A method of manufacturing a liquid crystal display substrate, comprising forming a portion of a second electrode substrate and then separating the portion of the first electrode substrate and the portion of the second electrode substrate, wherein the non-linear region is provided in the one region. When forming the first metal of the resistance element, a metal portion for a black matrix is simultaneously formed in the other region electrically independently of the first metal, and the surface of the first metal is insulated. When forming the body, the black By anodic oxidation on the surface of the metal part for Torikusu constitutes a black matrix by forming an insulator.

[0020]

In the liquid crystal display substrate according to claim 1, the second
The black matrix formed on the electrode substrate is formed of the same material as the first metal and the insulator of the non-linear resistance element formed of the first metal-insulator-second metal formed on the first electrode substrate. Since the surface of the black matrix itself is an insulator because it is formed, it is possible to completely obscure the non-lighted part between the pixel electrodes without short-circuiting with the adjacent part. The contrast is improved.

According to a second aspect of the present invention, there is provided a method of manufacturing a substrate for a liquid crystal display device, wherein the first metal-insulator-is formed on a common substrate material.
When forming the first metal and the insulator of the non-linear resistance element made of the second metal, the metal serving as the black matrix and the insulator formed on the surface of this metal can be formed in parallel, so that the metal thin film is formed. No additional layer deposition and its patterning steps are required, the manufacturing cost is not significantly increased, the black matrix is not short-circuited with the adjacent part, and the non-lighted part between the pixel electrodes is completely covered. The shape of the display device can be changed, and the contrast of the display device is improved.

[0022]

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

FIG. 2 shows a sectional structure of one pixel in the liquid crystal display device, and shows a portion cut along the line II of FIG.

The liquid crystal display device shown in FIG. 2 includes a first electrode substrate 11 which is a substrate on the matrix array pattern side, a second electrode substrate 12 which is a substrate on the opposite electrode pattern side, and these first electrode substrates. 11 and the liquid crystal composition 13 sandwiched between the second electrode substrate 12.

The first electrode substrate 11 is made of silicon oxide (Si
It has a plurality of stripe-shaped signal electrodes 16 shown in FIG. 6 formed on a glass substrate 15 as a substrate material of O ₂ ) coated soda lime. The signal electrode 16 is formed along the lateral direction, and a metal-insulator-which serves as a switching element for each pixel is provided on a side portion of the signal electrode 16.
A non-linear resistance element 17 which is a metal (Metal-Insulator-Metal) element is integrally formed.
A corresponding pixel electrode 18 is electrically connected to 17.
The glass substrate 15 and the pixel electrode 18 are an alignment film.
Covered by 19.

The non-linear resistance element 17 has a laminated structure of a first metal 21 made of tantalum (Ta) integrated with the signal electrode, an insulator 22, and a second metal 23 made of titanium (Ti). It was done.

On the other hand, the second electrode substrate 12 is also made of SiO.
_A plurality of stripe-shaped counter electrodes 26 made of a transparent electrode material such as ITO are formed in parallel on a glass substrate 15 having _two coats. As shown in FIG. 4, the width dimension of the counter electrode 26 is set to be slightly larger than the display range for one pixel, and the counter electrode 26 is formed on the first electrode substrate 11 in the length direction. It is combined so as to be orthogonal to the signal electrode 16.

Further, on the second electrode substrate 12, as shown in FIG.
Further, the black matrix 28 is formed in the hatched portion in FIG. 6, that is, in the non-lighted portion between the pixels. The black matrix 28 is formed by forming an insulator 30 on a metal 29 provided on a glass substrate 15 as shown in FIG. 2, and is the first non-linear resistance element 17 formed on the first electrode substrate 11 side. The first metal 21 and the insulator 22 are the same as the first metal 21 and the insulator 22, and are formed in the same manner as the first metal 21 and the insulator 22. The black matrix 28 and the counter electrode 26 are covered with an alignment film 31.

A liquid crystal display device comprising the first electrode substrate 11, the second electrode substrate 12 and the liquid crystal composition 13 is shown in FIG.
, Each signal electrode 16 of the first electrode substrate 11 is connected to the signal electrode driving means 35, and each counter electrode 26 of the second electrode substrate 12 is connected to the counter electrode driving means 36. The liquid crystal display device is operated by being controlled by the control means 37. Each of the signal electrode driving means 35 and the counter electrode driving means 36 is composed of a shift register and a driver circuit, and sequentially applies information signals in synchronization with the timing signal from the control means 37.

Here, since the surface portion of the black stripe 28 is the insulator 30, it is not necessary to consider a short circuit with an adjacent portion, and as shown in FIG. The size and shape of the facing portion can be completely covered, and the contrast of the display device can be improved.

Next, a method of manufacturing such a liquid crystal display device will be described with reference to FIGS.

In FIG. 3, the soda-lime glass substrate 15 coated with SiO ₂ which is a substrate material is initially an integral one, and a portion of the first electrode substrate 11 is formed in one region,
Portions of the second electrode substrate 12 are formed in the other regions, respectively. These first electrode substrate 11 and second electrode substrate 12
Are cut off at the time of completion of formation.

FIG. 4 shows the second electrode substrate in FIG.
12 part A is shown enlarged, and FIG. 5 shows the first electrode substrate 11 part B in FIG. 3 enlarged. further,
FIG. 2 shows a state in which the first electrode substrate 11 and the second electrode substrate 12 are combined in a predetermined relationship as a liquid crystal display device.
It shows about pixels.

FIG. 1 is a view for explaining a manufacturing process of the respective electrode substrates 11 and 12, and the right part shows a VV cross section of the part B of the first electrode substrate 11 shown in FIG. The left part shows the IV-IV cross section of the part A of the second electrode substrate 12 shown in FIG.

The manufacturing steps of the electrode substrates 11 and 12 will be sequentially described below.

First, as shown in FIG. 1A, a tantalum (Ta) film is formed on a glass substrate 15 by sputtering.
41 is formed with a film thickness of 3000 angstroms. At this time, in the initial state of sputtering, 1
By adding about 0% oxygen, the oxide layer (not shown) of about 300 angstrom, which is the contact surface of the tantalum film 41 with the glass substrate 15, can secure good adhesion. Further, an effect of preventing reflection of external light on the surface of the tantalum film 41 is also produced.

Next, resists 42a and 42b are applied at predetermined positions on the tantalum film 41, and then exposure and development are performed using a mask. In the portion B of the first electrode substrate 11, the signal electrode 16 and the nonlinearity are formed. A resist pattern for forming the first metal 21 of the resistance element 17 is formed. Further, a resist pattern for forming the metal 29 of the black matrix 28 is formed on the portion A of the second electrode substrate 12. And glass substrate
15 is dry-etched in plasma in which CF ₄ and O ₂ gas are mixed at a ratio of 1: 2 to form a desired pattern,
As shown in FIG. 1B, the first metal 21 of the signal electrode 16 and the nonlinear resistance element 17 and the metal 29 for the black matrix 28 are obtained.

Then, the surface of the signal electrode 16 and the surface of the first metal 21 of the nonlinear resistance element 17 is subjected to a treatment by an anodic oxidation method (AO method) in a 0.01 wt% citric acid aqueous solution, and these signals are processed. An insulator 22 having a film thickness of 700 angstrom is formed on the surfaces of the electrode 16 and the nonlinear resistance element 17. At the same time when the insulator 22 is formed, a black matrix is formed.
Different formation voltages are applied to the surface of the metal 29 for 28 by the AO method to form the insulator 30 having a film thickness of 1700 angstroms on the surface of the metal 29.

Next, a titanium (Ti) film having a film thickness of 1500 angstrom is formed on the insulator 22 formed on the portion B of the first electrode substrate 11 by sputtering, and a resist is applied to this titanium film region. .. Then, exposure and development are performed using a mask, etching is performed with a mixed solution of ammonia water, hydrogen peroxide water, ethylenediaminetetraacetic acid (EDTA) and water, and as shown in FIG. A second metal 23 is formed of a titanium film only on the top.
As a result, the signal electrode 16 and the non-linear resistance element 17 are formed on the portion B of the first electrode substrate 11, and the black matrix 28 is formed on the portion A of the second electrode substrate 12.

Next, as shown in FIG. 1D, an ITO film is formed.
43 is formed on the entire surface by sputtering. And
A resist 44 having a predetermined shape is provided to form the pixel electrode 18 and the counter electrode 26 connected to the nonlinear resistance element 17.

After this, an etching process is performed to obtain the structure shown in FIG.
As shown in (e), the second metal 23 of the nonlinear resistance element 17 is
The pixel electrode 18 connected to the black matrix 28 and the stripe-shaped counter electrode 26 provided on the black matrix 28 are formed.

In this way, the portion B of the first electrode substrate 11 and the portion A of the second electrode substrate 12 are formed on the same glass substrate 15.
And are formed. After the portion B of the first electrode substrate 11 and the portion A of the second electrode substrate 12 are formed, the portion B of the first electrode substrate 11 and the portion A of the second electrode substrate 12 are cut. , Part B of the first electrode substrate 11 and the second electrode substrate
Alignment film 1 made of polyimide resin on the upper surface of 12 part A
The alignment direction of the liquid crystal composition 13 is regulated by applying 9,31 and baking and labyrinth.

Then, the signal electrode 16 of the first electrode substrate 11 and the counter electrode 26 of the second electrode substrate 12 are opposed to each other in a direction orthogonal to each other, and the pixel electrode 18 and the counter electrode overlap each other. The liquid crystal composition 13 is injected between the first electrode substrate 11 and the second electrode substrate 12 to be assembled integrally. That is, the direction of the long axis of the molecule of the liquid crystal composition 13 is
Twist 90 ° between 11 and 12 to maintain a distance of 5 to 20 μm.

Further, as shown in FIG. 2, polarizing plates 51 and 52 may be arranged outside the first electrode substrate 11 and the second electrode substrate 12 with their polarization axes twisted by 90 °.

According to the above manufacturing method, the same glass substrate
When the non-linear resistance element 17 is formed on the black matrix 15, the black matrix 28 can also be formed in parallel by the same method, so that the deposition of the metal thin film layer and its patterning step are not added unlike the conventional case. , The manufacturing cost will not increase significantly.

In the above description, the material of the non-linear resistance element 17 and the like is illustrated, but other materials may be used.

[0047]

According to the substrate for a liquid crystal display device of the first aspect, the black matrix formed on the second electrode substrate is replaced by the first metal-insulator-formed on the first electrode substrate.
It is made of the same material as the first metal and the insulator of the non-linear resistance element made of the second metal, and since the surface of the black matrix itself is an insulator, it does not short-circuit with the adjacent portion, so that the pixel electrode The non-lighted portion between them can be completely covered, and the contrast as a display device can be improved.

According to the method of manufacturing a substrate for a liquid crystal display device of the second aspect, the first metal of the non-linear resistance element made of the first metal-insulator-second metal is formed on a common substrate material. When forming the insulator, the metal to be the black matrix and the insulator formed on the surface of the metal can be formed in parallel, so that the deposition of the metal thin film layer and its patterning step are not added, The manufacturing cost is not significantly increased, the black stripe is not short-circuited with the adjacent part, and the non-lighted part between the pixel electrodes can be completely covered, and the contrast as a display device is improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a process chart illustrating an embodiment of a method for manufacturing a substrate for a liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view showing one pixel portion of the above liquid crystal display device.

FIG. 3 is a plan view showing a substrate for a liquid crystal display device of the above.

4 is an enlarged view showing a portion A of the second substrate shown in FIG.

5 is an enlarged view showing a portion B of the first substrate shown in FIG.

FIG. 6 is a plan view showing one pixel portion in which the portions of FIGS. 4 and 5 are combined.

FIG. 7 is a block diagram showing a circuit configuration of the above liquid crystal display device.

FIG. 8 is a plan view showing the display state of the same liquid crystal display device for one pixel.

FIG. 9 is a plan view showing a display state of a conventional liquid crystal display device for one pixel.

[Explanation of symbols]

 11 First Electrode Substrate 12 Second Electrode Substrate 15 Glass Substrate 17 Nonlinear Resistance Element 18 Pixel Electrode 21 First Metal 22 Insulator 23 Second Metal 26 Counter Electrode 28 Black Matrix 29 Metal 30 Insulator

Claims (2)

[Claims] 1. A first electrode substrate having a plurality of pixel electrodes and a non-linear resistance element made of a first metal-insulator-second metal electrically connected to each of the pixel electrodes, In a substrate for a liquid crystal display device in which a second electrode substrate having a counter electrode facing each pixel electrode of the first electrode substrate is formed so as to be divisible within the same substrate material, the counter electrode is formed. A black matrix having a shape substantially equal to the non-lighted portion is provided on a portion of the second electrode substrate facing the non-lighted portion between the pixel electrodes on the first electrode substrate. A substrate for a liquid crystal display device, which is formed of the same material as the first metal-insulator constituting the above. 2. A plurality of pixel electrodes and a non-linear resistance element made of a first metal-insulator-second metal electrically connected to each of the pixel electrodes are formed in one region of a substrate material. To form a portion of the first electrode substrate, and a black matrix for the counter electrode and each of the pixel electrodes is formed in the other region of the substrate material to form a portion of the second electrode substrate. A method of manufacturing a liquid crystal display substrate, wherein a first electrode substrate portion and a second electrode substrate portion are separated from each other, wherein when the first metal of the non-linear resistance element is formed in the one region, A metal part for the black matrix is formed in the other region at the same time electrically independently of the first metal, and a metal part for the black matrix is formed when an insulator is formed on the surface of the first metal. The surface of the Method of manufacturing a substrate for a liquid crystal display device characterized by forming the black matrix by forming an insulator Te.