JPS62291002A - Manufacturing method of thin film 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 3. Detailed Description of the Invention (Field of Industrial Application) The present invention provides a temperature detector for use in, for example, a toner fixing roller of a copying machine or a heat-sensitive part of office automation (OA) equipment. This invention relates to improvements in the manufacturing method of thin film thermistors used as

(Prior Art) Conventionally, in the toner fixing roller of a copying machine, the above-mentioned office automation equipment, etc., a thermistor is mechanically brought into contact with the object whose temperature is to be detected, and the temperature is measured in the temperature range of 100°C to 300″C. Detecting temperature.

Incidentally, various types of thermistors of this type have been developed based on their components and manufacturing methods, such as metal composite oxide sintered thermistors, SiC thin film thermistors, metal composite oxide thin film thermistors, and the like.

■The metal composite oxide sintered thermistor includes manganese Mn,
Cobalt Go, nickel Ni or Mn.

A metal composite oxide containing Co and Ni as main components and copper Cu or iron Fe etc. is mixed and molded, and
It is made by sintering at a high temperature of 200'C to 1300''C.

(2) A thin SiC thermistor is a thin SiC thermistor in which a SiC thin film is formed on an alumina substrate by high-frequency sputtering in an argon-Ar gas atmosphere using a SiC sintered body as a target. The substrate temperature during the sputtering leg is 650°C.
~750'c.

■, Metal composite oxide WjI! There are two types of thermistors, one of which uses a thermistor material in which chromium Cr or Fe is added to two to three components of Mn, Co, and Ni to produce a sintering target.

Furthermore, using this sintered target, a thin film is formed on an alumina substrate by sputtering in an Ar gas atmosphere. Next, heat treatment is performed in the atmosphere to complete the thin film thermistor.

The other method uses a sintered oxide target made of Mn3C02Nil and is heated at 400°C to 500° in a sputtering gas containing Ar mixed with 3% or more oxygen by volume.
A thermistor thin film is formed on a high melting point glass substrate heated to C.

(Problems to be Solved by the Invention) However, the thermistor described above has various problems as described below.

(2) Metal composite oxide sintered thermistors are not suitable for miniaturization, and it is difficult to shorten the thermal response time constant.

08Next, in order to obtain a stable SiC film with good crystallinity, the 5iciillll thermistor requires a substrate temperature of 650°C.
It is necessary to raise the temperature to 750°C, which undeniably lowers productivity. In addition, the thermistor constant is approximately 2000
It is very small, and its resistance value changes little due to temperature changes, making it impossible to detect concentration with high accuracy. Thermistor constant changes depending on humidity. As a result, when temperature is detected over a wide range, linearity is poor. Additionally, if a small amount of nitrogen is mixed into the sputtering gas, the resistance value will change significantly.
It is difficult to obtain products of consistent quality.

(2) Metal composite oxide thin film thermistors are thermally unstable as they are sputtered and cannot be used as thermistors. For this reason, it is necessary to perform heat treatment at an N temperature of around 1000"C. Also, the characteristics of the thermistor depend on the heat treatment temperature, making it difficult to set the conditions. In order to obtain a thermally stable thin film thermistor with good crystallinity, is the substrate temperature ^temperature (
400°C~500'c), 3ic
As with the thermistor, it is undeniable that productivity will decrease.

The present invention has been made in view of the above circumstances, and aims to provide a method for manufacturing a thin film thermistor that has a large thermistor constant, is excellent in thermal stability, has an extremely short thermal response time constant, and is suitable for productivity and mass production. purpose.

(Means for Solving the Problems) A method for manufacturing a thin film thermistor according to the present invention includes a method of manufacturing a thin film thermistor by forming a composite oxide of Mn, co, and Ni or a composite oxide of Mn, co, and Ni on an insulating substrate.
Co, 2 to 3 components of Ni, AI, and Fe.

Using a sintered body of a composite oxide containing one or more components of Cr and Cu as a target, the composite oxide of the aforementioned components is formed by high-frequency sputtering in an Ar gas atmosphere without heating the substrate. It is manufactured by forming a thermistor thin film and then heat-treating it in the atmosphere.

(Function) Therefore, according to the method for manufacturing a thin film thermistor using the above means, the metal composite oxide *S is formed on the insulating substrate without heating the substrate, and then heat treatment is performed in the atmosphere. This aims to improve thermal stability, create a product with a short thermal response time constant, and create a manufacturing process suitable for productivity and mass production.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a cross section of a thin film thermistor, 1
is an insulating substrate, which is formed by, for example, thermal oxidation on a single crystal silicon substrate.

Silicon oxide using CVD method or sputtering method.

Use a material coated with an insulating layer such as silicon nitride alumina. A thermistor 1m112 is formed on the upper side of this insulating substrate 1. In forming this thermistor film 2,
Metal composite oxide of Mn, Go, Ni or Mn, Co
, a metal composite oxide in which one or more components of AI, Cr, Cu, Fe, etc. are added to two to three components in Ni is sintered and used as a target. This sintered target may be manufactured by a general manufacturing method for ordinary thermistor materials.

Of course, the metal composite oxide sintered body having the above-mentioned components may be manufactured by other methods. Then, high-frequency sputtering is performed in an Ar gas atmosphere using the target as described above to form a thermistor thin film 2 of the metal composite oxide having the above-mentioned components on the insulating substrate. During this high frequency sputtering, the insulating substrate 1 is not heated.

After forming the thermistor thin film as described above, a protective film 3 of silicon oxide, alumina, etc. is formed by high frequency sputtering. The formation of the protective film 3 at this time minimizes the change in specific resistance due to heat treatment and shortens the processing time. The reason why the protective film 3 was provided was to solve the problem that in metal composite oxide thermistors, the proportion of oxygen in the composition changes depending on the temperature, which inhibits the thermal stability of the resistivity. Niho! 1vA3 is provided. Next, heat treatment is performed in the atmosphere at a temperature slightly higher than the operating temperature for 50 to 250 hours. In the figure, 4 indicates an electrode.

Therefore, according to the above manufacturing method, the metal composite oxide 2 formed on the insulating substrate 1 has a fine but stable crystal structure, and can be heat-treated for a sufficiently long time even at a relatively low temperature. By doing so, it is possible to produce a product that is thermally stable and does not change over time.

Next, a specific example of manufacturing the thermistor 1llll12 and its manufactured ilN! The characteristics of the thermistor will be described.

Regarding the first manufacturing example.

First, Mn-35N i -4A I (wt%) (D
A metal oxide sintered body was prepared as a target, and using this target, a composite oxide thermistor S film 2 was formed on the insulating substrate 1 by high frequency sputtering in an Ar gas atmosphere at a pressure of 1 mTorr. At this time, the high frequency power was 200 W and the film forming rate was 0.8 μm/hour. During this sputtering, the substrate 1 is not heated. Furthermore, a protective film 3 was formed using silicon oxide. Thereafter, heat treatment was performed at 3000°C for 100 hours in the air.

As a result, the thermistor constant was 4950, and the specific resistance was 25.
A *si thermistor of 00Ω"Cm (100°C) was obtained.

In addition, a transmission electron microscope sample was prepared on rock salt under the same conditions as in the above production example, and when observed using the electron microscope, it was revealed that a stable spinel structure, although fine, was obtained. (See Figure 2).

Regarding the second manufacturing example.

The manufacturing means of this thermistor film 2 is Mn-15Go-
A metal oxide sintered body of 5N i (wt%) was prepared as a target, and the thermistor is2 and protection wi43 were formed on the insulating substrate 1 under substantially the same conditions as in the first manufacturing example. However, the film formation rate was 1 μm/hour. After that, heat treatment was performed at 200"C in the atmosphere.
The figure shows the relationship between specific resistance and heat treatment time. As is clear from FIG. 3, the change in specific resistance at this time increased to about 15% after 200 hours and became constant, indicating thermal stability. With this manufacturing method, the thermistor constant is 4500 and the resistivity is 25000-am (
A thin film thermistor of 100' c) was obtained.

20- Therefore, according to the manufacturing method of the thin film thermistor of the above embodiment, the thermistor thin film 2 has a thickness of, for example, 0.5 to several μm.
It can be formed to have a thin film thickness of 2,500 to 5,000, and the thermistor constant can be as high as 4,500 to 5,000. As a result, an Ill thermistor with excellent thermal stability and a short thermal time constant can be obtained. Furthermore, there is no need to heat the insulating substrate 1 when forming the thermistor register 112. In particular, heating the insulating substrate 1 in a vacuum requires a long time due to extremely insufficient heat conduction, which significantly reduces productivity; however, in this manufacturing method, the insulating substrate 1 is Although the process requires no heating and the heat treatment time in the atmosphere is long, it is possible to process a large amount at once, and when considering the entire manufacturing process, productivity can be significantly improved.

(Effects of the Invention) As detailed above, according to the present invention, a thermistor with a large constant and excellent thermal stability can be obtained, and the thermal response time constant can be shortened, improving productivity and mass production. It is possible to provide a method for manufacturing a thin film thermistor at a low cost that can be increased.

[Brief explanation of the drawing]

Figures 1 to 3 are shown to explain the present invention in detail. Figure 1 is a cross-sectional view of a thin film thermistor, Figure 2 is a spinel structure diagram of thermistor WIN observed with a transmission electron microscope, and Figure 2 is a diagram of the spinel structure of thermistor WIN observed with a transmission electron microscope. FIG. 3 is a characteristic diagram showing the relationship between the elapsed time of heat treatment in the atmosphere and the specific resistance of the thermistor thin film. 1... Insulating substrate, 2... Composite oxide thermistor 111.3... Preservation fIM. Applicant's agent Patent attorney Takehiko Suzue No. 1 rM - Hyoake Time (Kama) No. 3 (!I Engraving of the drawings (no change in content) Figure 2 Procedural Amendment (Method Showa 1961/Mon. 9)・Second Patent Office Commissioner Kuro 1) Akio Yu, Patent Application No. 1988-134619 2, Name of the invention Method for manufacturing thin film thermistors 3, Relationship with the person making the amendment case Patent applicant 4, Agent 1986 8 July 26, 7, Contents of amendment (1) The statement ``Figure 2 is a diagram of the spinel structure of a thermistor thin film observed with a transmission electron microscope'' on page 11, line 6 to line 7 of the same page of the specification was changed to `` Figure 2 is a diagram showing the metal structure of a thermistor thin film observed with a transmission electron microscope.'' (2) Figure 2 of the drawing is revised as shown in the attached sheet.

Claims (1)

[Claims] On an insulating substrate, a composite oxide of Mn, Co, and Ni or 2 to 3 components of Mn, Co, and Ni with Al, Fe, Cr,
Using a sintered body of a composite oxide containing one or more components of Cu as a target, and producing a thermistor of a composite oxide made of the aforementioned components by high-frequency sputtering in an Ar gas atmosphere without heating the substrate. A method for manufacturing a thin film thermistor, which comprises forming a thin film and then heat-treating it in the atmosphere.