JPH0348822A - Production of mim type nonlinear switching element - Google Patents

Abstract

PURPOSE:To obtain the MIM element which has stable and good reproducibility and with which current-voltage characteristics having to fluctuations are obtainable by forming insulators on the surfaces of metals patterns on a substrate and subjecting the insulators to a treatment for impressing a voltage thereto and passing a current therethrough. CONSTITUTION:After tantalum is formed as the metal 2 over the entire surface on the glass substrate 1, the metal 2 is patterned by etching. The insulators 3 consisting of tantalum oxide are thereafter formed by an anodic oxidation method or thermal oxidation method, etc., on the metals 2. The metals 2 are partly coated with protective films etc., to leave regions 11 where the insulators 3 are not formed. Transparent picture element electrodes 4 are then formed by patterning of ITO. Probes 12 are pressed to the regions 11 where the transparent picture element electrodes 4 and the insulating films 3 are not formed. The insulating films 3 are then subjected to the current annealing treatment by using a DC power source 13. The MIM element which is free from the fluctuations in the current-voltage characteristics and has the stable and good reproducibility is produced in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a switching element having a three-layer structure of metal-insulator-metal among switching elements installed in a liquid crystal display device (
The present invention relates to a method for manufacturing a Metal-Insulator-Metae (hereinafter referred to as an MIM element).

[Conventional technology]

MIM elements have electrical characteristics such as high resistance when the applied voltage is low and low resistance when the applied voltage is high, and can be easily formed on glass substrates, so they are used as switching elements in liquid crystal display devices. It is proposed to use.

A conventional method of manufacturing this MIM element will be explained with reference to FIG.

First, tantalum (T
Form a). Thereafter, a photosensitive resin is formed on the entire surface, and the photosensitive resin is patterned by exposure and development using a mask.The metal 2 is etched using the patterned photosensitive resin as an etching mask. pattern.

Next, an insulator 3 is formed on this metal 2 using an anodic oxidation method, a thermal oxidation method, or the like.

After that, a transparent conductive film is formed on the entire surface of the glass substrate 1, and this transparent conductive film is formed on the transparent pixel electrode 4 using photoetching.
The MIM device is manufactured by patterning it in the shape of . (Japanese Unexamined Patent Publication No. 57-196290) [Problems to be Solved by the Invention] The present invention has the following five problems when attempting to use an MIM element as a switching element installed in a liquid crystal display device. This was discovered through experiments conducted by researchers.

(a) There are large variations in the current-voltage characteristics of MIM elements that have just been manufactured.

(Due to large variations in the current-voltage characteristics of the IMIM element, the stability and reproducibility of the current-voltage characteristics of the IMIM element are significantly reduced.

An object of the present invention is to provide a method for manufacturing an MIM element that provides stable current-voltage characteristics with good reproducibility and no variation.

[Means to solve the problem]

Through experiments conducted by the inventor, the inventor has determined that M1.
Although the current-voltage characteristics of the M element are very unstable, it has been discovered that if current continues to flow through the M I M element, the current-voltage characteristics gradually become stable and the variations gradually disappear.

Based on this discovery, in order to achieve the above object, the present invention performs a so-called current annealing process in which a voltage is applied to the insulator and a current is caused to flow therethrough after the insulator is formed.

[Example 1] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIGS. 1(a) to 1(d) show MI in one embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a method for manufacturing an M element in the order of steps, and FIG. 2 is a plan view of an MIM element according to the present invention. below,
This will be explained with reference to FIGS. 1 and 2.

First, as shown in FIG. 1(a), tantalum is deposited as a metal 2 on a glass substrate 1 using a sputtering method.
It is formed with a thickness of m to 5QQnm.

Thereafter, as shown in FIG. 1(b), tantalum is etched using photoetching to pattern the metal 2.

Thereafter, tantalum, which is the metal 2, is anodized in a 0.5 g/l to 50 g/l citric acid solution to obtain an insulator 6 as shown in FIG. 1(C).

Alternatively, instead of this anodizing method, a temperature of 200°C to 4°C can be used.
Heat treatment in an oxygen atmosphere at 50'C (performing the so-called thermal oxidation method.Tantalum oxide as the insulator 6 formed by anodic oxidation or thermal oxidation has a thickness of 5 nm to 1100 nm.
Form to a thickness of . Alternatively, tantalum oxide, silicon oxide,
Silicon nitride or the like is formed over the entire surface to a thickness of 5 nm to 1100 nm. At this time, as shown in FIG. 3, a part of the metal 2 is covered with a protective film or the like to leave a region 11 where the insulator 6 is not formed. Alternatively, after forming the insulator 6, the insulator 6 is partially removed by etching so that the probe 12 can touch the metal.

Thereafter, as shown in FIG. 1(d), a transparent conductive film made of, for example, ITO (In2) is used to form a transparent pixel electrode 4.
O3-snow) is formed to a thickness of 50 nm to 500 nm using a sputtering method, a vapor deposition method, etc., and the ITO is patterned by photoetching to form an MIM element.

Thereafter, as shown in FIG. 3, the probe 12 is applied to the region 11 where the transparent pixel electrode 4 and the insulating film 6 are not formed, and the DC power supply 16 is used to apply a voltage of -20V to 20V for 1 time.
A current annealing process for 10 seconds to 10 minutes is performed on all pixel electrodes. Alternatively, an AC power supply may be used instead of a DC power supply, and an AC voltage having an amplitude of 5V to 20V and a frequency of 1k [1z or less] may be applied.

In this way, an MIM element is obtained.

[Example 2] The metal 2 is patterned by the method described in Example 1 to form the insulator 6. At this time, a region 11 where the insulator 3 is not formed is left as shown in FIG. After that, when forming ITO as a transparent pixel electrode 4 on the entire surface,
As shown in FIG. 4, a region 15 where no ITO is formed is left.

A region 15 where ITO is not formed is left so that ITO and metal 2 do not come into direct contact. Or ITO is formed on the entire surface,
Even if the metal 2 and ITO do not come into direct contact 5, the ITO is partially removed by etching, the result is the same.

Thereafter, as shown in FIG.
A DC voltage or an AC voltage is applied between them by the method described in Example 1, and a current is passed through the insulator 6 to perform current annealing.

After that, as shown in FIG. 1(d), ITO is applied to transparent pixels'
A MIM element is obtained by patterning into a shape with a weight of 4.

[Example 3] The metal 2 is formed by the method described in Example 1, and the insulator 6 is formed. At this time, as shown in FIG. 5, as described in Example 2, an insulator 6
Area 11 with no area is left.

Thereafter, as shown in FIG. 5, a conductive material 17 such as conductive rubber or metal is pressed onto the insulator 3 so as not to come into direct contact with the metal 2, and between the metal 6 and the conductive material 17, Apply DC voltage or AC voltage under the conditions described in 1.
A current is applied to perform current annealing.

Thereafter, as described in Example 1, a transparent conductive film made of, for example, ITO is formed on the entire surface and patterned into the shape of the transparent pixel electrode 4 to obtain an MIM element.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to eliminate variations in the current-voltage characteristics of MIM elements and to manufacture MIM elements with stable reproducibility. If the present invention is applied to the manufacture of liquid crystal display devices, the effects will be tremendous.

[Brief explanation of drawings]

FIGS. 1(a) to 1(d) show MI in one embodiment of the present invention.
2 is a plan view showing an MIM element in an embodiment of the present invention; FIG. 3 is a schematic diagram of current annealing in the first embodiment; Fig. 4 is a schematic diagram of current annealing in the second embodiment, Fig. 5 is a schematic diagram of current annealing in the third embodiment, and Fig. 6 is a schematic diagram of the MIM element manufactured by the conventional manufacturing method. FIG. 1...Glass substrate, 2...Metal, 3...Insulator, 4...Transparent pixel electrode. Figure 1 Figure 2

Claims (1)

[Claims] A process of forming a metal on the entire surface of a glass substrate and patterning the metal by first photo-etching, a process of forming an insulator on the surface of the metal, and a process of applying a voltage to the insulator to flow a current. a step of forming a transparent conductive film on the entire surface and patterning the transparent conductive film in the shape of a transparent pixel electrode by second photo-etching. .