JPS61113207A - Manufacture of oxide semiconductor for thermistor - 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 method for manufacturing an oxide semiconductor for medium to high temperature thermistors that can be used at 200°C to 500°C.

Conventional structure and its problems Well-known Mn -Go -Ni -C
U-oxide thermistor materials have been mainly used as general-purpose disk-type thermistors, but they cannot be used at high temperatures exceeding 300°C because the resistance value fluctuates significantly when used at high temperatures. It has been used at temperatures below 300°C. On the other hand, stabilized zirconia (ZrO2-Y2
O,, Zr○, -Ca○, etc.), MgAM-Cr-Fe
Oxide spinel systems, etc. have been developed (Special Publication Publication No. 48-7)
05 Publication, Special Publication No. 49-63995, Special Publication No. 5
(Japanese Patent Publication No. 0-16894, Japanese Patent Publication No. 50-16895, Japanese Patent Application Laid-open No. 53-33756), these oxide materials must also be fired at a high temperature exceeding 1600°C. It cannot be fired using a normal electric furnace (maximum 1600°C). Moreover, even in the case of sintered bodies of these oxides, the change in resistance value over time is large, and even those that are extremely stable are only about 10% (after 100 hours), posing a problem in stability over time.

In addition, the demand for thermistors with excellent stability at 200°C to 500°C has increased in the sensor market, and thermistor materials (Mn Ni-A1 oxide type: JP-A-57-95603, (N It Mgy Z
nz) Mn, O, spinel system: JP-A-57-11187
Publication No. 01, (NipCoq FeFAILsMns)
o4 spinel type: JP-A-57-88702, etc.)
have been proposed, but are still in the evaluation stage. The present inventor also responded to the above request.

Mn-Ni-Cr-Zr oxide system (patent application 1986-131)
No. 265).

Purpose of the Invention The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a method for manufacturing an oxide semiconductor for a thermistor that exhibits an appropriate resistance value even at 300°C to 500°C and can be stably used. It's about doing.

Structure of the Invention In order to achieve the above object, the method for manufacturing a thermistor oxide semiconductor of the present invention is to add zirconia with Gd as a stabilizing element to Mn-Ni-Cr-based oxide spinel, that is, a metal element As, Mn, Ni, Cr, Z
Gadolinium oxide-containing zirconia is used as a starting material to obtain a thermistor containing a total of 100 atomic percent of the five types of r and Gd.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Commercially available raw materials M n CO2, Ni○, Cr, O, and Gd2O, 3moA-containing ZrO2 provided by the manufacturer
Mn: Ni: Cr: Zr=76, O:
It was blended so that it was 2.0 2 2.0 2 20.0 atomic %. To illustrate the thermistor manufacturing process,
These blended compositions were wet mixed in a ball mill, the resulting slurry was dried and calcined at 1000° C., and the calcined product was wet-pulverized and mixed again in a ball mill. After drying the obtained slurry, polyvinyl alcohol is added and mixed as a binder, and a required amount is taken and molded into a block of 30 waφ×15+nmt. This molded body was fired in air at 1400°C for 2 hours. From the block thus obtained, slice,
After polishing, a wafer having a thickness of 150 to 400 μm is taken out, and platinum electrodes are provided by screen printing. This electroded wafer is cut into chips of desired dimensions. This element is sealed in a glass tube in argon gas or air and hermetically isolated from the outside air.

500℃ of the thermistor sensor manufactured in this way
The solid line (1) shows the rate of change in resistance value over time in the graph of the drawing.
It was shown in For comparison, the same graph also shows the rate of change in resistance value over time of the thermistor sensor using the already proposed Mn-Ni-Cr Zr oxide material with a dashed line (3
), and using zirconia and gadolinium oxide as raw materials instead of stabilized zirconia with the same composition ratio as in this example, the resistance value change rate over time of the sensor obtained through the same manufacturing process was 5 (2 ) 6 The dimensions of the element used in the sensor are 400 p + w x 400
μrs×300 μm.

The initial resistance value of the sensor at 25℃, 300℃ and 50℃
The thermistor constant B determined from the resistance values at two points at 0°C is also shown in the following table.

(The mark indicates a comparative sample) As is clear from the graph, according to the manufacturing method of the present invention, compared with that of samples Na2 and Nα3.

It has particularly excellent stability at high temperatures.

Paying attention to the microstructure of the sample, gadolinium oxide-containing zirconia does not form a solid solution in Mn-Ni-Cr-based oxide spinel crystals, but exists as crystal joints or crystal grains themselves. On the other hand, in the case where Gd2O and ZrO are blended at the same time, ZrO2 exists as the joint of the Rispinel crystal or as the crystal grain itself, but
The X
This was revealed by line microanalysis. Further, even by the xs diffraction method, it was not possible to fix the Mn-Ni-C,r-Gd-based oxide.

In this case, the sensor was created by enclosing an element cut out from a block, but it is also possible to use a bead type element, and there are no restrictions on the sensor creation method.

In the examples of the present invention, zirconia boulders were used for mixing raw materials and pulverizing and mixing calcined products. As a result of elemental analysis of the sample (sintered body) of the example described above, the amount of Zr mixed in was 0.0% with respect to 100 atomic % of the thermistor constituent elements.
It was 5 at% or less. Furthermore, when agate boulders were used, the amount of SL mixed was 1.0 at % or less.

Effects of the Invention As explained above, by using the method of manufacturing an oxide semiconductor for a thermistor of the present invention, a temperature sensor with a small change in resistance value over time in the range of 200°C to 500°C can be obtained, and Reliability is required. For example, it can be expected to contribute to application fields such as temperature control in microwave ovens and oil burners.

[Brief explanation of drawings]

The drawing is a graph showing the resistance value change characteristics of a glass-encapsulated thermistor over time. Agent Yoshi Morimoto Dispel, S! 1
town? J7 (hp)

Claims (1)

[Claims] 1. A thermistor characterized in that zirconia containing gadolinium oxide is used as a starting material to obtain an oxide semiconductor for a thermistor containing a total of 100 atomic % of five types of metal elements: manganese, nickel, chromium, zirconium, and gadolinium. A method for manufacturing an oxide semiconductor for use.