JPH01283524A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To eliminate the fluctuation in the element characteristics within a substrate by providing an intermediate layer to a nonlinear resistance 2-terminal element for switching and forming the intermediate layer of the oxide of an electrode material under the element. CONSTITUTION:The intermediate layer is provided to the nonlinear resistance 2-terminal element for switching. This intermediate layer is formed of the oxide of the electrode material under the element. Ta which is the lower electrode material is first formed on Ba borosilicate glass substrate 1 and the electrode 2 is formed by dry etching using gaseous CF4+O2. The layer 6 is then formed by bias sputtering of Ta2O5 and thereafter, a contact hole is opened in the intermediate layer by dry etching using gaseous CF4+O2. Thermal oxidation is then executed in the atm. to form a thermally oxidized film in the contact hole part 4. Further, Cr is sputtered and the upper electrode 3 is formed by using a Mr. Murakami liquid. The picture element electrode connecting to the upper electrode is then formed of ITO. No differences are thereby admitted in the element characteristics within the same substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a nonlinear resistance two-terminal element for switching of a liquid crystal display device.

[Conventional technology]

MIM and MSI, which are nonlinear resistance two-terminal elements for switching in active matrix liquid crystal display devices, each have an insulating layer, 5elli-1, sandwiched between two electrodes.
The mechanism of non-linear current-voltage characteristics that utilizes the property of nsulator to flow current in a high electric field is shown in 5 shots.
tky, Poole-Frenke 1 mechanism, etc. A cross-sectional view of a conventional MIM element is shown in Fig. 2, a top view is shown in Fig. 3, and a cross-sectional view of a conventional MSI element is shown in Fig. 4. In the conventional MIM, the lower electrode (Fig. 2-2) is etched. After formation, an insulating layer (Fig. 2-4) was formed by anodic oxidation, and the upper electrode was electrically connected to the pixel electrode. Furthermore, in the conventional MSI, a pixel electrode is etched and patterned, then a sputtering or CVD fseni-1 nsulator is formed, and a scanning electrode is formed thereon. These structures,
As understood from the manufacturing method, the lower element electrode (Fig. 2-
2. In FIGS. 4-5), etched end faces (ET in the figure) are inevitably formed, and conventionally, these etched end faces have been used as element drive parts.

[Problem to be solved by the invention]

Generally, the etched end face of the material changes in quality to a greater or lesser extent, regardless of whether it is dry or wet. Ions, etc. contained in the etching liquid or etching gas diffuse into the material to be etched to form an alloy, and may also enter or substitute between atoms of the material, significantly changing the structure. Furthermore, by-products generated during etching may adhere to the etched end face and cannot be easily removed.

However, in the conventional technology, as shown in FIGS. 2, 3, and 4, these altered electrode etched end surfaces were present in the element drive section, which caused variations in element characteristics and deterioration of element characteristics. was there. Figure 5 (A),
(B) shows the current-voltage characteristics of MSI and MIM devices created using the conventional technology within the same substrate. At a voltage of 10 V, the element resistance differs by about 2@ depending on the elements in the substrate, and the current-voltage characteristics are also sufficient. Since the slope is not steep, high-quality display is impossible. In addition, when forming the upper electrode, the height difference of the lower electrode cannot be fully absorbed, causing wire breakage, and even if this does not occur, the upper amount f2 width changes, and as a result, the element area changes.
This caused fluctuations in element characteristics, leading to deterioration in image quality.

On the other hand, in order to solve these problems, attempts have been made to provide an intermediate layer between conventional elements, but similar to the embodiment of the present invention shown in FIG. Do not use the etched end face as the element drive part.
This was an attempt to stably determine the element area and avoid disconnection of the four poles, but the decisive difference from the embodiments of the present invention was that a film other than the oxide of the lower electrode was used as the intermediate layer. . Diffusion into the lower electrode occurs during film formation of this slanted intermediate layer or during a post-process thermal process, causing abnormalities in device characteristics, making it impossible to improve image quality.

[Means to solve the problem]

A plurality of row electrodes and a plurality of column electrodes are arranged on a counter substrate to intersect with each other, and a pixel portion formed in a matrix at the intersection of these two electrodes is provided with an MTM or MSI switch.
In an active matrix liquid crystal display device in which a 2-terminal nonlinear resistance element for switching and a liquid crystal are electrically connected in series, an intermediate layer is provided in the 2-terminal nonlinear resistance element for switching, and the intermediate layer is an electrode under the element. It is characterized by being an oxide of the material.

[Example-1] Example-1 of the present invention is shown in FIG. 1. First, Ta, which is a lower electrode material, was sputtered at 3500A on Ba borosilicate glass, and electrodes were formed by dry etching using CFA 102 gas. 0th order Ta.

0, with a 2500A bias sputter (intermediate layer (Fig. 1-
6) After forming 2), a 5 μm contact hole is made in the intermediate layer by dry etching using CF4+Ot gas again. At this time, the gas composition was adjusted to increase the etching rate ratio of TazOs/Ta, and the etching of Ta was minimized.

Next, thermal oxidation was performed at 500℃XIHr in the air for about 5
A thermal oxide film of about 0.0A is formed in the contact hole portion (Fig. 1-4), and an upper electrode is formed by sputtering 1,500 Cr using Murakami's solution (Fig. 1-3). A pixel electrode was formed using ITO. Figure 5-(
As shown in c), the slope was slightly steeper than before, and no difference was observed in the device characteristics within the same substrate, and there was also no disconnection of the upper electrode.

In addition, in the embodiment of the present invention, Ta was used as the lower electrode material of the MIM element, but its electrical resistance is low, and its oxide is 2000 to 30
Any material may be used as long as it is transparent and insulating, such as Aj, Or, etc.

[Example 2] Example 2 of the present invention is shown in FIG. 6. First, a scanning electrode with a thickness of 3000 was formed using AJI, and an intermediate layer was formed on top of it in the same manner as in Example 1. At this time, the intermediate layer is a coated and fired film of alkoxide of Aj with a thickness of 2,500 mm, and the holes are formed using a phosphoric acid aqueous solution by sputtering of 0-order SiNx of 600 mm. The patterning of 5INx was done by dry etching using CF gas.
Next, a pixel electrode ITO was formed to cover the contact hole portion. The current-voltage characteristics of the MSI element formed in this way are shown in Figure 5-(D), and the slope is slightly steeper than that of the conventional one, and there is no discernible difference in the element characteristics within the same substrate. Similarly, there was no disconnection of #l (pixel electrode).

In the embodiment of the present invention, the lower electrode (scanning electrode) of the MSI element
Aj was used as the material, but its electrical resistance is low, and its oxide is 2
000-3000, any transparent and insulating material may be used, for example, Ta, Or, etc. may be used.

〔Effect of the invention〕

As described above, according to the invention, a plurality of row electrodes and a plurality of column electrodes are arranged on a counter substrate to intersect therewith, and a pixel portion formed in a matrix at the intersection of these two electrodes is provided. In an active matrix liquid crystal display device in which an MIM or MSI switching nonlinear resistance 2-terminal element and a liquid crystal are electrically connected in series, an intermediate layer is provided in the switching nonlinear resistance 2-terminal element, and the intermediate layer is By using an oxide as the element lower electrode material, variations in element characteristics within the substrate can be eliminated, and disconnection of the upper electrode can also be eliminated. This has the effect of completely eliminating image quality deterioration called spots and unevenness, which have been problems when conventional liquid crystal panels display halftones. In addition, we were able to obtain a steep current-voltage characteristic in which the element resistance changes by 3 steps between 5 and 10 cm, so even when driving a liquid crystal panel at 1/1000 deuti, it is possible to obtain high-quality images without causing tarostalk. did it. In recent years, display devices of 100 inches or more have been manufactured by combining a large number of liquid crystal panels in order to increase the size of the display screen, but these display devices are extremely difficult to view due to variations in the characteristics of each liquid crystal panel. However, by using the present invention, it is possible to easily produce a product with good swivel visibility that eliminates variations in characteristics between manufacturing lots.

Needless to say, the manufacturing yield is also improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an MIM element showing Example-1 of the present invention. FIGS. 2 and 3 are a cross-sectional view and a top view of a conventional MIM element. Figure 4 is a cross-sectional view of a conventional MSI element, Figure 5
The figure is a current-voltage characteristic diagram showing characteristics and characteristic variations of an embodiment of the present invention and conventional MIM and MSI elements, and FIG. 6 is a sectional view of an MSI element showing an embodiment of the present invention. ■...Substrate 2...Lower electrode 3...Upper electrode 4...Insulating layer 5...Image quality electrode 6...Intermediate layer 7 ---Sem1-Insulator8...Scanning electrode ET...・Electrode etching end face and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kisanbe Kisanbe Ca1 name) Figure 1 Taku 20 No. 30 System diagram

Claims (1)

[Claims] A plurality of row electrodes and a plurality of column electrodes are arranged on a counter substrate to intersect with each other, and a pixel portion formed in a matrix at the intersection of these two electrodes is provided with two terminals of a nonlinear resistor for MIM or MSI switching. In an active matrix liquid crystal display device in which an element and a liquid crystal are electrically connected in series, the switching nonlinear resistance two-terminal element has an intermediate layer, and the intermediate layer is an oxide of an element lower electrode material. A liquid crystal display device characterized by: