JPH04369625A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To suppress the increase in the resistance of lead wiring electrodes and to prevent the degradation in display grade by connecting a metallic thin film of the 1st layer constituting an MIM element to a picture element electrode and constituting the lead wiring electrode of a metallic thin film of the 2nd layer of a metallic thin film and the 3rd layer having the resistance lower than the resistance of this layer. CONSTITUTION:The MIM element 14 constituted of the metallic thin film 11 of the 1st layer, the anodized film 12 thereof and the metallic thin film 13 of the 2nd layer is disposed on one main surface of an insulating substrate 10. A picture element electrode 15 is connected to the metallic thin film 11 of the 1st layer. The lead wiring electrode 17 is constituted of the metallic thin film 13 of the 2nd layer and the metallic this film 16 of the 3rd layer having the resistance lower than the resistance of this film. A counter electrode 19 is formed on one main surface of the insulating substrate 18. Two sheets of the insulating substrates 10, 18 are so combined that the respective main surface sides thereof face each other. A liquid crystal layer 20 is crimped in this spacing. Then, the increase in the resistance of the lead wiring electrode 17 is suppressed without impairing the element characteristics of the MIM element 14. The degradation in the display grade by the trend toward the larger sizes of the screen and the higher accuracy is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device equipped with MIM elements, and particularly to its structure.

0002

[Prior Art] In recent years, display devices using liquid crystal displays have been
It has been used for large-capacity information display applications such as personal computers, word processors, office automation terminal equipment, and TV image displays, and higher image quality is now required. It's here. There are various types of switching (element row) arrays, but two have a simple structure and are easy to manufacture.
Among the terminal nonlinear resistance elements, the MIM type is one that is currently in practical use.

FIG. 3 is a diagram showing an example of a matrix type liquid crystal display device equipped with a conventional MIM element.
is a plan view showing the structure of one pixel, and (b) is a plan view showing the structure of one pixel.
FIG. 3 is a cross-sectional view of the element portion corresponding to the AA' cross section of FIG. To explain this according to the manufacturing process, first, a first layer metal thin film (Ta) 2, which also serves as the lower metal of the MIM element and the lead wiring electrode, is formed on the insulating substrate 1, and then patterned into a predetermined shape. After that, an insulating film (Ta2) is formed on the surface by anodic oxidation.
O5 )3 is formed. Next, a second metal thin film (T
a, Cr, Ti, etc.) 4 is formed into a film and patterned into a predetermined shape. Finally, the pixel transparent electrode (ITO) 5 is formed and
Perform patterning.

0004

[Problems to be Solved by the Invention] However, in order to make the display screen larger and higher in definition, the lead wiring electrodes must be made longer and thinner, so the liquid crystal display as shown in FIG. In display devices, the wiring resistance of lead wiring electrodes increases. In order to prevent this lead wiring electrode from increasing in resistance, the first layer metal thin film can be changed to a metal with lower resistance, but the first layer metal thin film also serves as the metal under the MIM element.
Since the insulating film of the MIM element is formed on the surface by anodic oxidation, this change has a large influence on the characteristics of the MIM element, limits the range of metal material selection, and cannot be an effective means. Further, increasing the thickness of the first metal thin film to lower the resistance causes an open on the side surface of the MIM element. Furthermore, by providing a low-resistance metal thin film under the first layer metal thin film and making the lead wiring electrode into a two-layer structure to lower the wiring resistance, the metal underneath the MIM element will also have a two-layer structure. MI due to leakage current on the side of the low-resistance metal thin film
Degrades the characteristics of the M element. In this way, in a matrix type liquid crystal display device equipped with MIM elements of the conventional structure,
It is difficult to prevent the lead wiring electrode from becoming high in resistance. This increase in the resistance of the lead wiring electrode causes the waveform of the applied selection (signal) pulse voltage to become dull, resulting in a problem of deterioration of display quality.

[0005] The present invention was made in view of the above circumstances, and its purpose is to suppress the increase in resistance of lead wiring electrodes and prevent the resulting deterioration of display quality without affecting the characteristics of the MIM element. do.

[0006]

[Means for Solving the Problems] The present invention provides a liquid crystal display in which an MIM element connected to a lead wiring electrode and a pixel electrode are arranged for each pixel on at least one of two insulating substrates sandwiching a liquid crystal layer. This is about display devices. The MIM element is formed by a first metal thin film, an anodized film of the first metal thin film, and a second metal thin film,
The pixel electrode is connected to the first metal thin film, and the lead wiring electrode is made up of the second metal thin film and the third metal thin film, which has a lower resistance.

[0007]

[Operation] In this invention, the third layer metal thin film, which is a part of the lead wiring electrode and has a lower resistance than the second layer metal thin film,
Since the structure is designed to avoid contact with the insulating layer of the element, the resistance of the lead wiring electrode can be reduced without deteriorating the characteristics of the MIM element.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 1(a) is a plan view showing the structure of one pixel, and FIG. 1(b) is a plan view showing the structure of one pixel.
2 is a sectional view of the device in the element portion corresponding to the AA' section in FIG. As shown in FIG. 1, an insulating substrate 10
On one main surface is a first metal thin film 11, and its anodic oxide film 1.
MIM element 1 composed of 2 and second layer metal thin film 13
4 is arranged, and the pixel electrode 15 is connected to the first layer metal thin film 11. A lead wiring electrode 17 is constituted by the second metal thin film 13 and the third metal thin film 16. Further, a counter electrode 19 is formed on one main surface of the insulating substrate 18 . The two insulating substrates 10 and 18 are combined so that one main surface side faces each other, and a liquid crystal layer 20 is sandwiched between the two insulating substrates 10 and 18.

FIG. 2 shows the MIM element 14 in FIG. 1(a).
FIG. To explain this according to the manufacturing process, first, as shown in FIG. 2(a), ITO is formed into a film by sputtering, vapor deposition, etc. on an insulating substrate 10 made of glass, for example, and then patterned to form a pixel electrode. form 15. Next, the insulating substrate 10
After forming a film of Ta, for example, thereon, patterning is performed to form the first metal thin film 11. Subsequently, this first layer metal thin film 11 is anodized, as shown in FIG. 2(b).
An anodic oxide film 12 made of Ta2O5 is formed. Next, the first layer metal thin film 11 and anodic oxide film 12 are formed as shown in FIG. 2(c).
Pattern it into the shape shown in . Subsequently, after sequentially forming, for example, Cr and Al films on the insulating substrate 10, as shown in FIG.
A second metal thin film 13 made of Cr and a third metal thin film 1 made of Al are patterned into the shape shown in d).
form 6.

In this embodiment, a third metal thin film 16 having a lower resistance is provided on the second metal thin film 13 constituting the MIM element 14, and these two thin films are connected to the lead wiring electrode 1.
7, it is possible to reduce the lead wiring electrode resistance without impairing the device characteristics of the MIM element 14. As a result, it is possible to suppress an increase in lead wiring electrode resistance due to an increase in the size and capacity of a display screen, and to prevent a deterioration in display quality due to this. In addition, since the first layer metal thin film 11 is not used for the lead wiring electrode 17, an insulating film made of an anodic oxide film is not formed on the terminal portion for electrical connection to the outside of the board, and this can be prevented. There is no need to carry out the process of cleaning or removing it. Furthermore, in this embodiment, if the formation and patterning of the second layer metal thin film 13 is performed and then the formation and patterning of the third layer metal thin film 16 is performed, the originality of the lead wiring electrode 17 can be improved. ―
Poon can be definitely prevented.

Note that the first layer metal thin film 11 is patterned into the shape shown in FIG. 2(b) and then anodized. , in this part, the first layer metal thin film 11 and the second layer metal thin film 1
This is to prevent 3 from being shorted. In addition to Cr, the second metal thin film 13 may be made of Ta or Ti.
It may be.

[0013]

[Effects of the Invention] According to the present invention, the first metal thin film constituting the MIM element is connected to the pixel electrode, and the lead wiring electrode is formed by the second metal thin film and the third metal thin film having a lower resistance. As a result, it is possible to suppress an increase in the resistance of the lead wiring electrode without impairing the element characteristics of the MIM element, and to provide a liquid crystal display device that does not suffer from deterioration in display quality due to larger screens and higher definition.

[Brief explanation of drawings]

FIG. 1 is a plan view and a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing a manufacturing process in an embodiment of the present invention.

FIG. 3 is a plan view and a cross-sectional view showing an example of a conventional liquid crystal display device.

[Explanation of symbols]

10, 18...Insulating substrate 11...First layer metal thin film 12...Anodic oxide film 13...Second layer metal thin film 14...MIM element 15...Pixel electrode 16...Third layer metal thin film 17...Lead wiring electrode 20...Liquid crystal layer

Claims (1)

[Claims] 1. An MIM (MIM) connected to lead wiring electrodes on at least one of two insulating substrates sandwiching a liquid crystal layer.
In a liquid crystal display device in which a Metal-Insulator-Metal) element and a pixel electrode are arranged for each pixel, the MIM element is formed by a first metal thin film, an anodized film of the first metal thin film, and a second metal thin film. A liquid crystal display device characterized in that the pixel electrode is connected to the first layer metal thin film, and the lead wiring electrode is made of the second layer metal thin film and a third layer metal thin film having a lower resistance than the second layer metal thin film.