JPH1027702A - Thin film thermistor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a thin film thermistor to be improved in resistance to etching carried out in an after process by a method wherein a temperature- sensitive resistor film is formed on the surface of a plate-like insulating board of ceramic or glass, an insulating film is formed thereon and patterned, and a pair of electrodes are formed coming into contact with the edges of the patterned insulating film. SOLUTION: A temperature-sensitive resistor film 2 to is covered with an insulating film 4 before electrodes 3 and 3' are formed by patterning. Therefore, the temperature-sensitive resistor film 2 is not exposed to etching atmosphere, so that the temperature-sensitive resistor film 2 is kept free from a change in characteristics due to etching of the electrodes 3 and 3'. The temperature- sensitive resistor is covered with the insulating film 4 which screens the temperature-sensitive resistor film 2 from outside air and moisture, so that the temperature-sensitive resistor film 2 can be restrained from changing with time in properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film thermistor having a high resistance accuracy and a small change with time in resistance, and a method of manufacturing the same. The thin-film thermistor of the present invention has the feature of high-speed response, and can be used as a temperature sensor for applications such as measuring the temperature of a copying machine roller, measuring the temperature of an object to be heated in a microwave oven, and compensating for the temperature of driving a liquid crystal element. It is.

[0002]

2. Description of the Related Art FIG. 5 shows a schematic plan view of a conventional thin film thermistor. FIG. 6 is a schematic cross-sectional structure diagram of a conventional thin film thermistor, and corresponds to a cross-sectional structure diagram along line AA 'in FIG. 5 and 6, 1 indicates an insulating substrate, 2 indicates a temperature-sensitive resistor film, and 3 and 3 'indicate electrodes.

As shown in FIGS. 5 and 6, a conventional thin-film thermistor is formed by forming a thermistor film as a temperature-sensitive resistor film 2 on one surface of an insulating substrate 1 made of insulating glass or ceramic. Of the electrodes 3 and 3 '.

FIG. 7 shows a schematic plan view of a conventional thin film thermistor having a comb-shaped electrode structure. FIG. 8 is a schematic sectional view of a conventional thin film thermistor having a comb-shaped electrode structure, and corresponds to a sectional view taken along the line BB 'in FIG.
7 and 8, 1 is an insulating substrate, 2 is a temperature-sensitive resistor film, and 3 and 3 'are electrodes. A feature of FIGS. 7 and 8 is that a structure in which a pair of comb-shaped electrodes 3 and 3 ′ are formed to reduce resistance is used. In these thin-film thermistor element structures, the element resistance at an arbitrary temperature is determined by the characteristics of the temperature-sensitive resistor film 2 and the distance between the paired electrodes 3 and 3 '.

In the structure of a conventional thin film thermistor,
By changing the pattern dimensions of the electrodes 3 and 3 'with respect to the temperature-sensitive resistor film 2 having the same characteristics, it is possible to manufacture devices having various resistance value levels. During the manufacturing process, when the patterns of the electrodes 3 and 3 ′ are patterned by etching, the portion of the temperature-sensitive resistor film 2 functioning as a temperature-sensitive resistor is changed to an etching solution having a strong oxidizing property in wet etching, or to dry etching. Are exposed to highly reactive gases and plasma. As a result, the characteristics of the temperature-sensitive resistor film 2 change irreversibly. For this reason, it was difficult to control the resistance value of the thin film thermistor element.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the manufacturing process caused by the conventional thin-film thermistor element structure and to replace the portion of the temperature-sensitive resistor film functioning as a temperature-sensitive resistor with an insulating film. The thin film thermistor which maintains the resistance to the etching process in the subsequent process by protecting it, does not cause the irreversible characteristic change of the temperature-sensitive resistor film due to the manufacturing process, and can easily control the resistance value, and the thin film thermistor. It is to provide a manufacturing method.

[0007]

In order to solve the above-mentioned problems, in a thin film thermistor of the present invention, a temperature-sensitive resistor film (2) on an insulating substrate (1) is covered with an insulating film (4). The insulating film (4) other than the portion functioning as the temperature-sensitive resistor film (2) is removed by etching. The electrodes (3, 3 ') are formed so as to be in contact with the pattern of the insulating film (4) and form a pair with the pattern of the insulating film (4) interposed therebetween.
Therefore, in the step of patterning the electrodes (3, 3 '), the portion of the temperature-sensitive resistor film (2) functioning as the temperature-sensitive resistor of the element is covered with the insulating film (4),
The portion of the temperature-sensitive resistor film (2), which is a problem in the conventional thin film thermistor, is not exposed to the etching atmosphere.

Therefore, the configuration of the present invention is as follows. That is, a temperature-sensitive resistor film (2) is formed on one surface of an insulating substrate (1) made of insulating plate-like ceramic or glass, and an insulating film is further formed on the temperature-sensitive resistor film (2). After forming and patterning, a pair of electrodes (3, 3 ') is formed in contact with the pattern end of the already formed insulating film, thereby forming a thin film thermistor.

Alternatively, the temperature-sensitive resistor film (2) is
It has a configuration as a thin film thermistor characterized by being formed by a thin film of an oxide containing at least two or more elements selected from the elements of Mn, Ni, Co, Fe, Cu, Al and Cr. .

Alternatively, further, SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , Z
It has a configuration as a thin film thermistor characterized by forming an insulating film selected from rO ₂ and TiO ₂ .

Alternatively, a first step of forming a temperature-sensitive resistor film (2) on one main surface of the insulating substrate (1), and after the first step, the temperature-sensitive resistor film (2) Insulating film (4) on top
A second step of forming, a third step of patterning and removing the insulating film (4) after the second step, and a patterning of the insulating film (4) after the third step. Forming a pair of electrodes (3, 3 ') by patterning the pair of electrodes (3, 3').

Alternatively, the insulating substrate (1) is a flat ceramic or glass substrate, and has a configuration as a method of manufacturing a thin film thermistor.

Alternatively, the temperature-sensitive resistor film (2) is
A method of manufacturing a thin-film thermistor, characterized in that the thin-film thermistor is formed by a thin film of an oxide containing at least two or more elements selected from the elements of Mn, Ni, Co, Fe, Cu, Al, and Cr. Having a configuration.

Alternatively, the insulating film (4) formed on the temperature-sensitive resistor film (2) may be made of SiO ₂ , Si
Has a configuration as a method of manufacturing a thin film thermistor according to claim _{3 N 4, Al 2 O 3} , ZrO 2, it is formed by a thin film selected from among TiO _2.

[0015]

In the thin-film thermistor of the present invention, the portion of the temperature-sensitive resistor film (2) functioning as the temperature-sensitive resistor of the element is formed by the insulating film (4) before the electrode (3, 3 ') patterning step.
Coated. Therefore, the temperature-sensitive resistor film (2) is not exposed to the etching atmosphere, and the characteristics of the temperature-sensitive resistor film (2) are improved by the electrode (3, 3 ') etching, which is a problem in the conventional thin film thermistor. Does not change.
An insulating film (4) covering the temperature-sensitive resistor film (2)
Cuts off the outside air and moisture from the temperature-sensitive resistor film (2), and suppresses the characteristics of the temperature-sensitive resistor from changing over time.

[0016]

FIG. 1 is a schematic plan view showing a thin film thermistor according to a first embodiment of the present invention, and FIG. 2 is a schematic sectional view showing a thin film thermistor according to the first embodiment of the present invention. 1 and corresponds to a sectional structural view taken along the line AA 'in FIG. In Example 1 shown in FIGS. 1 and 2, first, a rectangular temperature-sensitive resistor film 2 was formed on an insulating substrate 1 made of alumina. The temperature-sensitive resistor film 2 was formed by sputtering using an Mn-Ni-Co oxide target. The rectangular pattern was formed by etching. An insulating film 4 made of a SiO ₂ film is deposited on the temperature-sensitive resistor film 2 by RF sputtering, and the SiO ₂ film (4) other than the temperature-sensitive resistor portion of the element is formed by a lithography process.
It was dissolved and removed by wet etching. The type of the wet etching liquid is, for example, an HF + NH ₄ F liquid. This SiO ₂ film (4) is formed by a sol-gel method or plasma CVD.
It can also be formed by a method. Alternatively, the SiO ₂ film (4) can be formed by vacuum evaporation. When formed by the sol-gel method, no change in resistance of the temperature-sensitive resistor film 2 was observed before and after the film formation. When the film was formed by sputtering, the change in characteristics after the film formation could be recovered by annealing at an appropriate temperature. Even when the film was formed by vacuum deposition, there was no change in the characteristics of the thermistor film before and after the film formation. Further, P which becomes the electrodes 3 and 3 '
t was vacuum-deposited, and patterned by lithography so that each of the pair of electrodes 3 and 3 ′ was in contact with a different end of the pattern of the insulating film 4. It is needless to say that patterning of the temperature-sensitive resistor film 2 does not need to be particularly performed during the above steps. Further, a pair of electrode films of 3, 3 '
It may be formed by sputtering, or a conductive paste may be screen-printed and then fired to form a pattern, thereby eliminating the lithography process. Examples of the dimensions of each film thickness in Example 1 shown in FIGS. 1 and 2 are as follows. That is, the thermistor film thickness is 50
0 nm, Pt film thickness is 150 nm, SiO ₂ film thickness is 2
00 nm. In the case of forming a SiO ₂ film, in order to prevent pinholes, after forming a 100 nm film and then cleaning it, and further forming a 100 nm film, variations between products could be reduced.

FIG. 3 is a schematic plan view of a thin-film thermistor according to a second embodiment of the present invention, and FIG. 4 is a schematic cross-sectional view of a thin-film thermistor as a second embodiment of the present invention. 3 corresponds to a sectional structural view taken along line BB 'in FIG. In the second embodiment shown in FIGS. 3 and 4, in order to reduce the resistance,
The electrodes 3, 3 'were patterned and formed so as to have a comb structure. The manufacturing process of the second embodiment is the same as that of the first embodiment.

In the first and second embodiments, the element resistance at an arbitrary temperature is determined by the characteristics of the temperature-sensitive resistor film 2 and the pattern size of the insulating film 4. In the first and second embodiments, the element surface can be glass-sealed to prevent mechanical abrasion or to improve the stability over time of the temperature-sensitive resistor film 2. The insulating film 4 on the portion of the temperature-sensitive resistor film 2 prevented the reaction between the glass and the temperature-sensitive resistor film 2, and the characteristics of the temperature-sensitive resistor film 2 did not change.

[0019]

As described above, according to the thin film thermistor of the present invention and the method of manufacturing the same, the following effects can be obtained. The part of the temperature-sensitive resistor film that functions as the temperature-sensitive resistor of the element is
Because it is covered and protected by an insulating film before the electrode formation process,
The portion of the temperature-sensitive resistor film is not exposed to the electrode etching atmosphere. For this reason, an irreversible change in the characteristics of the temperature-sensitive resistor film does not occur, and a thin-film thermistor whose resistance value can be easily controlled and a method of manufacturing the same can be obtained.

The insulating film on the portion of the temperature-sensitive resistor film can suppress a change with time of the characteristics of the temperature-sensitive resistor film. When the element surface is sealed with glass, the reaction between glass and the temperature-sensitive resistor film is prevented by the insulating film, so that mechanical abrasion can be prevented or the stability over time can be made more complete. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a thin-film thermistor according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional structural view of the thin-film thermistor as a first embodiment of the present invention, taken along line AA ′ of FIG. 1;

FIG. 3 is a schematic plan view of a thin film thermistor according to a second embodiment of the present invention.

FIG. 4 is a schematic sectional view of a thin film thermistor according to a second embodiment of the present invention, taken along line BB ′ of FIG. 3;

FIG. 5 is a schematic plan view of a conventional thin film thermistor.

FIG. 6 is a schematic cross-sectional view of the conventional thin film thermistor taken along the line AA ′ in FIG.

FIG. 7 is a schematic plan view of a conventional thin film thermistor having a comb-shaped electrode structure.

8 is a schematic cross-sectional structural view of a conventional thin film thermistor having a comb-shaped electrode structure, taken along line BB ′ in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Temperature sensitive resistor film 3, 3 'electrode 4 Insulating film

Claims (7)

[Claims] A temperature-sensitive resistor film is formed on one surface of an insulating substrate made of an insulating plate-like ceramic or glass, and an insulating film is further formed on the temperature-sensitive resistor film and patterned. A thin film thermistor characterized in that a pair of electrodes is formed in contact with the pattern end of the already formed insulating film. 2. The temperature-sensitive resistor film comprises Mn, Ni, C
o, Fe, Cu, Al, Cr
2. The thin film thermistor according to claim 1, wherein the thin film thermistor is formed of an oxide thin film containing at least two or more elements. 3. The method according to claim 1, wherein the temperature-sensitive resistor film is formed of SiO.
_3. The thin film according to claim 1, wherein an insulating film selected from the group consisting of ₂ , Si ₃ N ₄ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ is formed. Thermistor. 4. A first step of forming a temperature-sensitive resistor film on one main surface of an insulating substrate, and a second step of forming an insulating film on the temperature-sensitive resistor film after the first step. A step of patterning and removing the insulating film after the second step; and contacting a patterned end of the insulating film after the third step to form a pair of electrodes. Forming a thin film thermistor by patterning. 5. The method according to claim 4, wherein the insulating substrate is a flat ceramic or glass substrate. 6. The temperature-sensitive resistor film comprises Mn, Ni, C
o, Fe, Cu, Al, Cr
6. The method for manufacturing a thin film thermistor according to claim 4, wherein the thin film thermistor is formed of a thin film of an oxide containing at least two or more elements. 7. The insulating film formed on the temperature-sensitive resistor film includes SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , and Zr.
O _2, of the claims 4 to 6, characterized in that it is formed by a thin film selected from among TiO _2, the method of manufacturing the thin film thermistor according to any one.