JPH06308538A - Production of liquid crystal display device - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for manufacturing a liquid crystal display device in which a light shielding layer is formed without increasing the number of steps. [Structure] A lower electrode 22 is formed on a glass substrate 21, and an oxide film 23 is formed on the surface of the lower electrode 22 by using an anodic oxidation method. The lower metal 27 is electrically isolated, and a black matrix 28 sufficiently thicker than the oxide film 23 is formed on the lower metal 27 by the second anodic oxidation process. Non-linear resistance element
The upper metal 24, 24 of chromium is formed on 25, and the wiring electrode 26 is formed on the black matrix 28. Non-linear resistance element 25
Then, the ITO pixel display electrode 29 is formed on the glass substrate 21. [Effect] Since the black matrix 28 is formed simultaneously with the lower metal 22 and the oxide film 23, the number of steps is not increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device in which a lower metal-insulator-upper metal (Metal-Insulator-Metal: MIM) element is provided on a substrate as a switching element.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have relatively simple structures such as clocks and calculators, personal computers, word processors, terminal equipment for office automation, image display of television sets, etc. Has been used for large-capacity display applications.

In the conventional liquid crystal display device,
It is common to use a multiplex drive system for matrix display, a so-called simple matrix system.

However, this simple matrix system is not suitable for large-scale matrix display because the contrast ratio between the display part and the non-display part deteriorates as the number of scanning lines increases.

Therefore, as a means for preventing deterioration of the contrast ratio, for example, a method of driving individual pixels by switching elements, that is, a so-called active matrix method has been developed.

A thin film transistor or a non-linear resistance element is used as the switching element, but a non-linear resistance element having two terminals and a simple structure is advantageous in terms of manufacturing cost.

Various methods have been developed for this non-linear resistance element. Among them, the one having a metal-insulator-metal (MIM) structure has been put into practical use at present, and the one having the MIM structure has been developed. An active matrix array substrate using a non-linear resistance element is usually formed by three photolithography steps of a first layer metal, a second layer metal and a pixel display electrode.

However, in the thus obtained active matrix array substrate, since the element structure is asymmetric, the current-voltage characteristics are not completely symmetrical between the positive polarity and the negative polarity. Such asymmetry of current-voltage characteristics causes a deterioration in display quality such as flicker and burn-in.

Therefore, as a constitution in which the current-voltage characteristic is made symmetrical with the positive polarity and the negative polarity, for example, JP-A-57-14 is used.
The structure described in Japanese Patent No. 4584 is known.

Next, the structure described in Japanese Patent Laid-Open No. 144584/1982 will be described according to the steps shown in FIGS.

First, a tantalum (Ta) layer 2 which is a metal of the first layer is formed into a thin film on a glass substrate 1 by a sputtering method, and the tantalum layer 2 is used for the first time as shown in FIG. A pattern of the non-linear resistance element 3 is formed by a photolithography process.

Next, as shown in FIG. 10, the tantalum layer 2
Surface is oxidized by an anodic oxidation method to 300-500.
An oxide film 4 having a thickness of about angstrom and serving as an insulator of the nonlinear resistance element 3 is formed.

Thereafter, as shown in FIGS. 11 and 12, each non-linear resistance element 3 is patterned into an island shape by using a second photolithography process to form the lower metal 5.
Are electrically isolated from each other.

Next, on the oxide film 4 and the glass substrate 1,
A chromium (Cr) layer, which is the metal of the second layer, is formed into a thin film using a sputtering method, and a third photolithography process is used to form an upper metal of the nonlinear resistance element 3 as shown in FIGS. 13 and 14. 6 and the wiring electrode 7 are formed.

Then, a transparent conductive film made of ITO (Indium Tin Oxide) is formed into a thin film by a sputtering method, and a fourth photolithography process is used to form a pixel display electrode as shown in FIGS. 8 is patterned.

Thus, an active matrix array substrate having a symmetric structure, that is, the non-linear resistance element 3 of the lower metal 5-oxide film 4-upper metal 6-upper metal 6-oxide film 4-lower metal 5 is completed.

FIG. 15 and FIG. 1 thus obtained
The active matrix array substrate shown in FIG. 6 is combined with the counter substrate 9 shown in FIG. 17 in which a transparent conductive film made of ITO (not shown) is patterned in a stripe shape to form a counter electrode so as to face each other with a gap, and an alignment treatment is performed on each. After the above steps, the liquid crystal display device shown in FIG. 18 is completed by laminating and injecting liquid crystal.

However, since the light transmitted through the portion corresponding to the shaded portion shown in FIG. 18 is not modulated, when the normally white mode is used, the black transmittance does not decrease and the contrast ratio becomes insufficient.

Therefore, a so-called black matrix 10 which is a light-shielding portion as shown in FIG. 17 is usually formed on a portion of the counter substrate 9 side corresponding to a portion where the pixel display electrode 8 is not provided.

[0020]

However, in order to form the black matrix 10, a photolithography process of the counter substrate 9 must be added, which causes a problem that the cost is increased due to the increase of the process.

The present invention has been made to solve the above problems, and an object thereof is to provide a method for manufacturing a liquid crystal display device in which a light shielding layer is formed without increasing the number of steps.

[0022]

According to the present invention, a plurality of pixel display electrodes and a non-linear resistance element having a lower metal-insulator-upper metal element structure electrically connected to the pixel display electrodes are formed on a substrate. In the liquid crystal display device in which the non-linear resistance element is connected to either one of the row and the column by the wiring electrode, an insulator is formed around the pixel display electrode when the lower metal-insulator of the non-linear resistance element is formed. The light shielding layer is formed.

[0023]

According to the present invention, when a non-linear resistance element having a lower metal-insulator-upper metal structure of a non-linear resistance element is formed on a substrate, a light-shielding layer is formed similarly at the same time as the insulator. The light-shielding layer can be formed without increasing the number.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An active matrix array substrate of an embodiment of the liquid crystal display device of the present invention will be described below with reference to the drawings.

This active matrix array substrate is
As shown in FIGS. 1 and 2, a lower metal 22 of a first metal layer made of tantalum (Ta), an oxide film 23 made of tantalum oxide, which is an insulator, on a glass substrate 21 having a transparent insulating property. It comprises a second metal layer upper metal 24 made of chromium (Cr), and has a non-linear resistance element 25 having an upper metal 24-oxide film 23-lower metal 22-oxide film 23-upper metal 24 structure.

A wiring electrode 26 made of chromium is connected to the nonlinear resistance element 25. The wiring electrode 26 is a lower metal 27 made of tantalum arranged on the glass substrate 21.
And a so-called black matrix 28 which is a light-shielding layer of an insulator made of tantalum oxide.

Further, ITO (In
A pixel display electrode 29 made of dium tin oxide) is formed.

Next, the manufacturing process of the active matrix array substrate will be described.

First, a thin film of the tantalum layer 31 is formed on the glass substrate 1 by using the sputtering method, and then the first photolithography process is used, as shown in FIGS. Black matrix 28
Pattern is formed.

Next, an oxide film 23 having a thickness of about 300 to 500 angstroms is formed on the surface of the tantalum layer 31 by using the anodic oxidation method, and the second photolithography process is used to form the oxide film 23. As shown in FIG. 5, each non-linear resistance element 25 is patterned into an island shape to form the lower metal 22 and the oxide film 23. Further, the patterned lower metal 27 around the periphery is electrically isolated, and by the second anodic oxidation process, the black matrix 28 having a thickness of about 2000 angstroms, which is sufficiently thicker than the thickness of the oxide film 23 on the lower metal 27, is formed. To form.

Then, a chromium layer is formed into a thin film by a sputtering method, and a third photolithography process is used to form the upper metals 24 and 24 of the non-linear resistance element 25 and the black as shown in FIGS. 6 and 7. The wiring electrodes 26 are formed on the matrix 28.

Further, ITO is formed by the sputtering method.
A transparent conductive film made of is formed into a thin film, and the fourth photolithography process is used to form pixel display electrodes 29 as shown in FIGS. 1 and 8 to complete the active matrix array substrate.

After that, the above-mentioned active matrix array substrate is combined with a counter substrate (not shown) that is patterned in stripes so that a plurality of scanning electrodes formed of ITO are orthogonal to the wiring electrodes, and after performing alignment treatment with each other. Laminated facing each other with a predetermined gap,
A liquid crystal display device is completed by injecting liquid crystal.

According to the above embodiment, the black matrix
Since 28 is similarly formed simultaneously with the lower metal 22 and the oxide film 23, the PEP (Photo Engraving Process) process does not increase.

Further, since the lower metal 22 and the oxide film 23 of the non-linear resistance element 25 are electrically isolated and the second anodic oxidation is performed, the characteristics of the non-linear resistance element 25 are not adversely affected and the black matrix 28 is not affected. The oxide film 23 can be formed sufficiently thick so that it does not affect the display.

[0036]

According to the method of manufacturing a liquid crystal display device of the present invention, when a non-linear resistance element having a lower metal-insulator-upper metal structure of a non-linear resistance element is formed on a substrate, at the same time as the insulation, Since the light shielding layer is formed on the substrate, the light shielding layer can be formed without increasing the number of steps.

[Brief description of drawings]

FIG. 1 is a cross-sectional view taken along the line I-I shown in FIG. 8 of an active matrix array substrate of an embodiment of the liquid crystal display device of the present invention.

FIG. 2 is a front view showing one step of manufacturing the same active matrix array substrate.

FIG. 3 is a sectional view taken along line III-III shown in FIG. 2 above.

FIG. 4 is a front view showing the next step of FIG. 2 above.

5 is a sectional view taken along line VV shown in FIG. 4 above.

FIG. 6 is a front view showing the next step of FIG. 4 above.

7 is a sectional view taken along line VII-VII shown in FIG. 6 above.

FIG. 8 is a front view showing the next step of FIG. 6 above.

FIG. 9 is a front view showing one step of an active matrix array substrate of a conventional liquid crystal display device.

10 is a sectional view taken along line XX shown in FIG. 9 above.

FIG. 11 is a front view showing the next step of FIG. 9 above.

12 is a sectional view taken along line XI-XI shown in FIG. 11 above.

FIG. 13 is a front view showing the next step of FIG. 11 above.

14 is a sectional view taken along line XIII-XIII shown in FIG. 13 above.

FIG. 15 is a front view showing the next step of FIG. 13 above.

16 is a sectional view taken along line XV-XV shown in FIG. 15 above.

FIG. 17 is a front view showing the counter substrate of the above.

FIG. 18 is a front view showing the above liquid crystal display device.

[Explanation of symbols]

 21 Glass substrate 22 Lower metal 23 Oxide film as insulator 24 Upper metal 25 Non-linear resistance element 26 Wiring electrode 28 Black matrix as light shielding layer 29 Pixel display electrode

Claims (1)

[Claims] 1. A plurality of pixel display electrodes, and a non-linear resistance element having a lower metal-insulator-upper metal element structure electrically connected to each of the pixel display electrodes is formed on a substrate. In a liquid crystal display device in which is connected to either one of a row and a column by a wiring electrode, a light shielding layer of an insulator is formed around the pixel display electrode when the lower metal-insulator of the nonlinear resistance element is formed. And a method for manufacturing a liquid crystal display device.