JPS62242311A - 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
ONI (known as 3 elements, which uses an amorphous semiconductor mainly composed of chalcogen elements as its material.
Similar electrical properties are known to be found 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 an active layer, and 4 is a substrate. Further, in FIG. 3, 6 is an active layer, 6 and 7 are electrodes, and 8 is a base.

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, which is not only disadvantageous in manufacturing yield and productivity. For example, it cannot be used for applications where it is necessary to construct an element on a very large substrate because of high costs and other reasons. An object of the present invention is to provide a nonlinear resistance element having switching characteristics that solves these problems and a method for manufacturing the same, and to enable these elements to 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 with 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 discovered a mixture of manganese oxide, cobalt oxide, and bismuth oxide as a compound that exhibits switching properties, and used this for the active layer.

OPERATION According to the invention, the thin film is a mixture of manganese, cobalt oxide and bismuth oxide.

It can be easily obtained by mixing and dissolving cobalt and bismuth compounds in a solvent, coating the mixture on a substrate, and thermally decomposing the mixture. At this time, by considering the combination of the compound and the solvent, a very stable solution can be obtained and can be stored as an ink for a long period of time.

By introducing such a formation method, methods such as dipping, spraying, and printing can be used, so that a uniform film can be manufactured over a large area with high productivity and at low cost. Furthermore, the thin film obtained by thermal decomposition exhibits switching characteristics in which the threshold voltage and sustaining current vary depending on the film thickness, interelectrode distance, 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, cobalt oxide and bismuth oxide was prepared with the composition shown in Table 1 below. Here, manganese.

As the cobalt and bismuth compound, 2-ethylhexanoate, which is very easy to form into a film, was used, 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 fired in the air at 650°C for 60 minutes to form an active layer. A thin film of gold was formed. When the knee characteristics of these elements are measured with a curve tracer when a voltage is applied, an IV curve as shown in FIG. 1 is obtained. The measurement results are also shown in Table 1 below, but in this table V
th (dark value voltage), Ith (threshold current) and Vh
(sustaining voltage) and Ih (maintaining current) are shown as numerical values. These values are all obtained when swept at a frequency of 5011z. 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) Furthermore, when we applied a sawtooth wave of ±16V at 60Z to these elements to examine the stability of their characteristics, we found that the stability of the characteristics remained constant for 10 consecutive days (equivalent to over 40,000 switching times). Even after the operation, the values shown in Table 1 did not vary by more than ±6%, and the stability of the characteristics was considered to be sufficient for practical use.

<Example 2> Using a coating solution having the same composition as in Example 1, a Zandwich type element was constructed by replacing the electrode with a tin-doped indium oxide thin film. The manufacturing method except for the electrodes was 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. Further, the sweep frequency is 5011z.

Table 2> 11,,-7 From this table, it can be seen that almost the same results as in Example 1 were obtained, although there were some variations. In addition, a stability test similar to that in Example 1 was conducted, and it was confirmed that the characteristics of these devices were stable even after approximately 4 million times or more of switching.

<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 Brehner type element shown in FIG. 3 was produced. When a DC voltage is applied to these and the knee V characteristics are measured, the first
A clear IV curve shown in the figure was obtained. The results are shown in Table 3 below. Similarly, in this Table 3, the sample boils correspond to the boils in Example 1.

(The following is a blank space) Table 3 It can be seen that in this Brehner-type Example 3, the threshold voltage increases in response to the larger inter-electrode spacing compared to the Sand-Inch 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 mm was immersed in the coating solution of Flat 8 of Example 1, pulled up at a speed of about 5 mm/36C, dried, and baked at 500'C for 90 minutes. A device was constructed by forming a thin film of a mixture of manganese oxide, cobalt oxide, and bismuth oxide on the surface of a stainless steel wire, and then forming a chime electrode on the surface of this film.

In this case, vth is 6 at a sweep frequency of 50tTz.
．． 3V% IthkaO, esmA, Vhka2. IV
, Ih power of 1-9 mA, switching characteristics similar to Examples 1 to 3 were observed.

In Examples 1 to 4, the firing humidity was 500 to 660°C in view of the heat resistance of the substrate and electrode materials used. However, when using a heat resistant substrate such as alumina, This humidity can be raised to the heat-resistant temperature of the substrate. In addition, 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 gold alkoxides, they can be used without any problem. can. Further, as the electrode material, copper, aluminum, zinc, gold M, etc. other than those in this example may be used.
It consists of a conductive oxide such as tin oxide doped with cadmium stannate or antimony, or a mixture thin film of manganese oxide, cobalt oxide and bismuth oxide, and an electrode for taking electrical leads from the thin film. A thin film of a mixture of bismuth oxide is formed by applying a solution of a manganese compound, a cobalt compound, and a bi2muth compound mixed and dissolved in a solvent onto a substrate, drying it, and then heating and baking it in the atmosphere. As a result, a nonlinear resistance element having switching characteristics can be provided at low cost with good productivity, and can be manufactured over a large area.

Its practical utility is great in that it is easy.

[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. Z, t...J''22 No. 4 Name of agent Patent attorney Toshio Nakao and one other person Figure 1 r Current reed 2 Trial 2 Figure 3 Defense x Wa 4ri 7 S)'ri For two reasons

Claims (2)

[Claims] (1) A nonlinear resistance element comprising a thin film of a mixture of manganese oxide, cobalt oxide, and bismuth oxide and an electrode for taking electrical leads therefrom, and having conductive switching characteristics. (2) A solution of a manganese compound, a cobalt compound, and a bismuth compound mixed and dissolved in a solvent is applied onto the substrate, dried, and then heated and fired to produce manganese oxide,
A method for manufacturing a nonlinear resistance element, comprising forming a thin film of a mixture of cobalt oxide and bismuth oxide.