JPH01271728A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain current-voltage characteristics which have no polarity difference by using two MIM and MSI terminal elements as nonlinear resistance elements for switching, providing an intermediate layer between the elements, and using the same material for respective insulating layers and two conductors between which a Semi-Insulator layer is sandwiched. CONSTITUTION:Nonlinear resistance elements for switching and liquid crystal are arranged while connected electrically in series with picture element parts formed in a matrix at intersection parts of row electrodes and column electrodes. Then, the two MIM and MSI terminal elements are used as the nonlinear resistance elements for switching and the intermediate layer 6 is provided between the elements to enable the same material to be used as the two conductors between which the semi-insulator layer 7 is sandwiched. Consequently, the nonlinear resistance two-terminal element for switching which has the current-voltage characteristics with no polarity difference is obtained.

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.

[Prior Art] MIM and MSI, which are nonlinear resistance two-terminal elements for switching in active matrix liquid crystal display devices, each have an insulating layer sandwiched between two electrodes, Semi=In
The mechanism of the nonlinear current-voltage characteristic of suj2ator, which utilizes the property of flowing current in a high electric field, is shown in 5 shots.
This is explained by the tky, POOI2e-Frenkej2 mechanism, etc. These conventional device structures are shown in Figure 2.
It is shown in Figure 3. In the conventional MIM, after forming the lower electrode Ta by dry etching (Fig. 2-2), forming an insulating layer by anodizing etc. (Fig. 2-4), and forming the upper electrode CrC by dry etching (Fig. 2-3).
) to establish continuity with the pixel electrode. At this time, the reason why Cr is used for the upper electrode is that the lower electrode Ta and the insulating layer are made of TaO.
It is possible to form a pattern without damaging x, and T a / T
a Current depending on polarity of Ox/Cr MIM element -
This is because the difference in voltage characteristics, that is, the difference in polarity, is relatively small among conductors other than Ta, and the negative resistance is also small. In addition, in conventional MSI, after etching and patterning the pixel electrode ITO, a Semi-Insulator is formed by sputtering or CVD.
A scanning electrode Cr was formed thereon. Cr on the scanning electrode
The reasons for using this method, as with the MIM described above, are problems in the manufacturing process, polarity differences in element characteristics, and electrical resistance.

[Problem to be solved by the invention] However, in the conventional technology, the insulating layer of MIM and the semi-
Since the two conductors sandwiching the insulation layer are made of different materials, a polarity difference in current-voltage characteristics inevitably occurs, resulting in a problem in that the display quality of the liquid crystal display device is degraded. As described in the prior art, even if the electrode materials sandwiching the insulating layer and the semi-insulator layer are appropriately selected, the polarity difference cannot be eliminated. As shown in Figure 4 (A) and (B), both MSI and MIM are 1.5 to 2 when a voltage of 15 V is applied.
It can be seen that the element resistance varies by about a factor of two depending on the polarity difference.

Therefore, the present invention is intended to solve these problems, and its purpose is to reduce current in a liquid crystal display device.
The object of the present invention is to obtain a switching nonlinear resistance two-terminal element with no polarity difference in voltage characteristics.

[Means for Solving the Problems] A plurality of row electrodes and a plurality of column electrodes are arranged on a counter substrate to intersect with each other, and switching is performed in a pixel portion formed in a matrix at the intersection of these two electrodes. In an active matrix liquid crystal display device in which a nonlinear resistance element for switching and a liquid crystal are arranged electrically connected in series, the nonlinear resistance element for switching is a two-terminal element of MIM and MSI, and an intermediate layer is provided between the elements. The feature is that the two conductors sandwiching each insulating layer and semi-insulator layer are made of the same material.

[Example-1] Example-1 of the present invention is shown in FIG. First, 3,500 pieces of Cr, which is a lower electrode material, is spun onto Ba borosilicate glass, and then wet etched using Murakami's solution to form an electrode. Next, after forming an intermediate layer (FIG. 1-6) by bias spacking with Si022500, a contact hole of 5 μm0 is made in the intermediate layer by dry etching using CF4+02 gas. At this time, the lower electrode Cr is not dry etched and serves as a stopper. Then in the atmosphere at 500℃
A thermal oxidation film of about 500 layers is formed in the contact hole by thermal oxidation of XIHr (FIG. 1-4). Further, 1,500 Cr was sputtered and the upper electrode was formed again using Murakami's solution (Fig. 1-3). At this time, since the Cr of the lower electrode is well covered with the SiO□ intermediate layer, it is not attacked by Murakami's solution at all. Next, a pixel electrode was formed using ITO on the upper electrode. Figure 4-(
Shown in C). It can be seen that no polarity difference can be confirmed and the slope is slightly steeper.

In the embodiment of the present invention, Cr was used for the upper and lower electrodes of the MIM element, and a SiO□ sputtered film was used for the intermediate layer. A combination of materials may also be used.

For example, ITO for the upper and lower electrodes and SiO□ or AR2 for the intermediate layer.
0a, /l of the upper and lower electrodes and SiO□ or Ta20 of the intermediate layer
5. SiNx, Cu and Ni in the upper and lower electrodes and Si in the intermediate layer
O2, Aρ203, Ta20g, etc. Further, the intermediate layer does not need to be a spuck film, and may be any material that can cover the lower electrode with good coverage, such as a CVD film or a coated and fired film of metal alkoxide.

[Example-2] Example-2 of the present invention is shown in FIG. First, a scan electrode with a thickness of 3500A was formed using ITO, and SiNx was placed on top of it.
00 people form spac. The patterning of SiNx is C
Dry etching was performed using F4 gas. Next, holes were formed in the intermediate layer in the same manner as in Example-1. At this time, the intermediate layer was a coated and fired film of alkoxide of A flood, the film thickness was 3000, and the holes were made using a phosphoric acid aqueous solution. Next, ITO was spun again for 1,500 times and patterned to form a pixel electrode (Fig. 5-5).

The current-voltage characteristics of the MSI element in which the upper and lower electrodes are made of the same material are shown in FIG. 4-(D).

As in Example-1, there is no polarity difference, and the slope is slightly steeper.

In addition, in the embodiment of the present invention, ITO1 is used for the upper and lower electrodes of the MSI element.
Although Ac103 is used for the intermediate layer, as described above, any combination of materials may be used as long as the intermediate layer is not attacked by the etching solution, dry etching gas, etc. used when patterning the upper electrode.

[Effects 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 matrix is formed at the intersection of these two electrodes. In an active matrix liquid crystal display device in which a nonlinear resistance element for switching and a liquid crystal are electrically connected in series in a pixel portion, the nonlinear resistance element for switching is connected to an MI.
M, MSI two-terminal element, and by providing an intermediate layer between the elements, each insulating layer, Se mi -
MIM has current-voltage characteristics with no polarity difference by using the same material for the two conductors sandwiching the In5uj2ator layer,
We were able to obtain an MSI device. As a result, we were able to improve the image quality by eliminating flickering in the display. Furthermore, the steepness of the current-voltage characteristics was also improved, which improved contrast and caused crosstalk even when driving the liquid crystal panel at 1/700 duty. It has the effect that there is no

[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 cross-sectional views of conventional MIM and MSI elements. Figure 4 shows the embodiment of the present invention and conventional MSI, MIM.
FIG. 3 is a current-voltage characteristic diagram showing the characteristics of the element. FIG. 5 is a sectional view of an MSI element showing Example-2 of the present invention. l...Substrate 2...Lower electrode 3...Upper electrode 4...Insulating layer 5...Pixel electrode 6...Intermediate layer 7...Semi-insulator 8...Scanning electrode and above Applications Person: Seiko Epson Co., Ltd. agent, patent attorney, Meiki Kisanbe (and 1 other person), 1 stick, 2 paper sheets, 2 drawings, 3 drawings

Claims (1)

[Claims] It is equipped with a plurality of row electrodes and a plurality of column electrodes arranged on a counter substrate so as to intersect with these electrodes, and a nonlinear resistance element for switching and a liquid crystal are electrically connected to a pixel section formed in a matrix at the intersection of these two electrodes. In an active matrix type liquid crystal display device, the switching nonlinear resistance element is a two-terminal element such as MIM or MSI, and by providing an intermediate layer between the elements, each insulating layer, Semi-Insulator A liquid crystal display device characterized in that two conductors sandwiching a layer are made of the same material.