JPS62242313A - Nonlinear resistance element and manufacture of the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a nonlinear resistance element having a function such as conductive switching and a method for manufacturing the same.
Can be used in the electronics industry.

Conventional technology Non-linear resistance elements such as conductive switching are 0V
It is known as an ONIC element and uses an amorphous semiconductor mainly composed of chalcogen elements as its material. Similar electrical properties are also known to be observed in transition metal oxides, such as hematite, magnetite, and nickel ferrite.

Nickel zinc ferrite, nickel oxide, etc. have been reported. These conventional nonlinear resistance elements use materials in the form of thin films or sintered bodies, but it is advantageous to construct them with thin films from the viewpoint of low threshold voltage, and they exhibit relatively stable characteristics. Most amorphous semiconductor devices are of the thin film type.

The basic structure of this is shown in FIGS. 2 and 3.

As described above, it can be divided into a sandwich type (FIG. 2) in which the formed film is used in the direction of its thickness and a planar type (FIG. 3) in which the film is used in the direction of its surface. In either case, the active layer is usually formed by vacuum evaporation or sputtering.

In Fig. 2, 1 and 3 are electrodes, 2 is electrode 3 ・=
4 is a substrate. Also, in Figure 3, 5
is an active layer, 6 and 7 are electrodes, and 8 is a substrate.

Problems to be Solved by the Invention As mentioned above, in conventional nonlinear resistance elements exhibiting switching characteristics, the active layer is formed by a vacuum method.
This is not only disadvantageous in terms of manufacturing yield and productivity, but also increases costs for applications that require devices to be constructed on very large substrates. I can do it. The purpose of the present invention is to
It is an object of the present invention to provide a nonlinear resistance element having switching characteristics that solves these problems, and a method for manufacturing the same, so that these elements can be manufactured with high productivity and at low cost.

Means for Solving the Problems In order to achieve the above object, the present invention adopts a method of applying a solution of a metal compound and thermal decomposition to form an active layer. Furthermore, any metal compound may be used as long as it dissolves in a suitable solvent and forms a film when the solution is applied and dried.

For example, inorganic acid salts such as nitrates, organic acid salts such as acetates, complexes, and organic metals having an alkyl group attached to the metal can be used. There are many compounds that can be used to form thin films using this method, but the inventors found a mixture of manganese oxide, bismuth oxide, and tin oxide as a compound that exhibits switching properties, and used this for the active layer.

According to the present invention, a thin film of a mixture of manganese oxide, bismuth oxide, and tin oxide can be easily obtained by dissolving a mixture of manganese, bismuth, and tin compounds in a solvent, coating the mixture on a substrate, and thermally decomposing the mixture. . At this time, by appropriately considering the combination of compound and solvent, a very stable solution can be obtained and can be stored as an ink for a long period of time. With the introduction of this formation method,
Since methods such as dipping, spraying, and printing can be used, a uniform film can be produced over a large area with good productivity and at low cost. In addition, the thin film obtained by pyrolysis exhibits switching characteristics in which the threshold voltage and sustaining current change depending on the film thickness, distance between electrodes, composition, etc., and the stability of these characteristics is very good.

Example The present invention will be described in detail below with reference to Examples.

<Example 1> In order to make the sandwich type element shown in FIG. 2, a coating solution for forming a thin film of a mixture of manganese oxide, bismuth oxide and tin oxide was prepared with the composition shown in Table 1 below. Here, 2-ethylhexanoate, which is very easy to form into a film, was used as the compound of manganese, bismuth, and tin, and methyl isobutyl ketone was used as the solvent. These coating solutions were spin-coded onto a glass substrate on which a thin gold film was formed as an electrode, dried at room temperature, and exposed to air for 50 minutes.
An active layer was formed by heating and baking at 50'C for 60 minutes, and a gold thin film was further formed on this thin film. When the IV characteristics of these elements are measured with a curve tracer when a voltage is applied, a knee curve as shown in FIG. 1 is obtained.

The measurement results are also shown in Table 1 below, which shows vth (threshold voltage), Eth (threshold current), vh (sustaining voltage), and Ih (maintaining current) in Figure 1 as numerical values. . All these values are values when swept at a frequency of 60) lz. The thickness of the active layer was measured by etching a part of this thin film to form a step and using a contact type surface roughness meter.

(Left below) 7. -7 9..-1 Furthermore, we applied a sawtooth wave of ±15V at sHz to these devices to examine the stability of their characteristics. Even after performing the above-mentioned switching operations, no fluctuations of more than ±5% were observed in the values shown in Table 1, and the stability of the characteristics was considered to be sufficient for practical use. .

<Example 2> Using a coating liquid having the same composition as in Example 1, a sandwich-type element was constructed by replacing the electrode with an indium oxide thin film doped with tin. The manufacturing method except for the electrodes is exactly the same as in Example 1. When these IV characteristics were measured with a curve tracer, IV curves as shown in FIG. 1 were similarly obtained, and the results are shown in Table 2 below. The samples in the table correspond to those in Table 1, and the same samples indicate that the active layer was formed using the same coating solution. The sweep frequency is 6oHz.

Table 2 11.-1 From this table, it can be seen that almost the same results as in Example 1 were obtained, although there were some variations. Further, stability tests similar to those in Example 1 were conducted, and it was confirmed that the characteristics were stable even after switching approximately 4 million times or more.

<Example 3> A thin gold film was formed on a glass substrate, a part of this thin film was etched to create a gap of several tens of microns in width, the gold thin film separated by this was used as an electrode, and the Example was placed on top of this. An active layer was formed using the same coating solution as in Example 1. The formation conditions are the same as in Example 1. In this way, the planar type element shown in FIG. 3 was produced. When applying a DC voltage to these and measuring the knee characteristics, the first
A beautiful IV curve shown in the figure was obtained. The results are shown in Table 3 below. Similarly, in this third table, the sample shop corresponds to the boil in Example 1.

(Margin below) <Table 3> 13, +-.

It can be seen that in this planar type Example 3, the threshold voltage increases in response to the larger inter-electrode spacing compared to the sandwich type element. It was confirmed that the stability of the properties in these cases was sufficient for practical use.

<Example 4> A stainless steel wire with a diameter of 1 m was immersed in the /I6.8 coating solution of Example 1, pulled up at a rate of about 5 g/sec, dried, and fired at 50° C. for 90 minutes.

A thin film of a mixture of manganese oxide, bismuth oxide, and tin oxide was formed on the surface of a stainless steel wire, and a silver electrode was further formed on the surface of this film to construct a device. In this case, at a sweep frequency of 50Hz, vth is 7.5v1 th is 0.5
mA, Vh is 2.3 V, Ih is 2.0 m
A switching characteristic similar to that of Examples 1 to 3 was observed.

In Examples 1 to 4, the firing temperature was 500 to 550°C from the viewpoint of the heat resistance of the substrate and electrode materials used.
For example, when using a heat-resistant glass such as alumina, this temperature can be raised to the heat-resistant temperature of the base. As for the compounds used, as long as they are soluble in an appropriate solvent, such as inorganic acid salts such as nitrates and sulfates, organic acid salts such as acetates, complex salts, and metal alkoxides, they can be used without any problems. . Furthermore, electrode materials may include metals other than those used in this example, such as copper, aluminum, and zinc, conductive oxides such as tin oxide doped with cadmium stannate, and antimony, or mixtures of manganese oxide, bismuth oxide, and tin oxide. Consisting of a thin film and an electrode for taking electrical leads from it, a thin film of a mixture of manganese oxide, bismuth oxide, and tin oxide is coated on a substrate with a solution of a manganese compound, a bismuth compound, and a tin compound mixed and dissolved in a solvent, and then dried. After that, by heating and firing in the atmosphere, a nonlinear resistance element with switching characteristics can be provided at low cost with high productivity, and it is easy to manufacture even over a large area. 15,,-7, its practical usefulness is great.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the current-voltage characteristics of the nonlinear resistance element of the present invention, FIG. 2 is a sectional view showing the structure of a sandwich type element, and FIG. 3 is a sectional view showing the structure of a planar type element. 2. ,! ; , 11. 27-17 layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Zuko Denbu

Claims (2)

[Claims] (1) A nonlinear resistance element comprising a thin film of a mixture of manganese oxide, bismuth oxide, and tin oxide and an electrode for taking electrical leads therefrom, and having conductive switching characteristics. (2) Forming a thin film of a mixture of manganese oxide, bismuth oxide, and tin oxide by applying a solution of a manganese compound, bismuth compound, and tin compound mixed and dissolved in a solvent onto a substrate, drying, heating, and baking. A method of manufacturing a nonlinear resistance element characterized by: