JPS63128165A - Thermosensitive resistor and its production - Google Patents

Abstract

PURPOSE:To produce the title thermosensitive resistor suitable for the practical resistance value as a thermistor by forming an amorphous film consisting of Si, C, Ta, etc., on the surface of a porcelain substrate by sputtering. CONSTITUTION:A sheet consisting of high-purity SiC and >=1 kind among Ta, Ni, Cr, Fe, etc., (expressed Ta, etc., hereunder) is placed on the cathode target in a high-frequency sputtering device, and the porcelain substrate set in a rotating cylindrical basket is arranged in opposition to the target. An inert gas such as Ar is introduced into the device, the device is kept at a specified vacuum, a high-frequency electric power is impressed to heat a substrate holder, etc., and hence to keep the porcelain substrate at about 300-400 deg.C, and sputtering is carried out. As a result, the amorphous film 1 consisting of the Ta, etc., C, and Si is formed. The material is then heat-treated at a specified temp., an electrode cap 2 of stainless steel is put on both ends, and the film 1 is helically cut to form a spiral groove 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses one or more types of metal, nickel, chromium, iron, etc., and silicon carbide as targets in a sputtering vapor deposition apparatus, and uses a porcelain substrate maintained at a relatively medium temperature. The present invention relates to a temperature-sensitive resistor in which an amorphous film made of carbon, silicon, tantalum, etc. is formed on the surface of the element, and then heat-treated (annealed) at a predetermined temperature.

(Prior art) A thermistor for high temperatures (more than 1000) with a polycrystalline silicon carbide film formed by sputtering vapor deposition was developed (Japanese Patent Publication No. 56-26965), and improvements in temperature/output voltage characteristics and detection sensitivity were developed. JP-A-57-12503 to form a two-layer film with different resistance-temperature characteristics in order to improve the resistance.
(No. 65), substrate temperature (65
0C) and film formation speed were pursued (Japanese Patent Laid-Open No. 56-122
No. 104), the substrate is coated with a glass layer to protect it from contamination in the environment in which it is used (Japanese Patent Application Laid-Open No. 56-1201)
Improvements such as 02 Publication) have been made. The films formed by these sputter depositions are made of polycrystalline silicon carbide because the substrate is in a high temperature range of around 650C, and its electrical conductivity is affected by impurity elements and various defects contained in the films. It is thought that lattice defects) are involved (Japanese Patent Application Laid-Open No. 122104/1983).

Because of this electrical conduction mechanism, the sheet resistance value becomes significantly high, and when put to practical use as a thermistor, a comb-shaped electrode with a thick film of platinum and gold baked on is used. The present invention provides a high-temperature temperature-sensitive resistor whose sheet resistance value can reach a practical resistance value as a thermistor, in which an amorphous film of carbon, silicon, tantalum, etc. is formed on the surface of the base material, and heat treatment is performed. The film is then helically cut, and will be explained in detail below based on the drawings.

(Means) A plate of high purity silicon carbide (8iC) and one or more types of tantalum, nickel, chromium, iron, etc. (hereinafter simply referred to as tantalum etc.) is placed on the cathode target in a high frequency sputtering device. , a porcelain substrate placed in a rotating cylindrical basket is placed opposite this target. Porcelain substrates made by sintering alumina silicate, magnesia silicate, mullite, etc. have excellent heat resistance and are widely used in film resistors and the like. Introducing an inert gas such as argon into the device, 2.0 to 2.2
The degree of vacuum is maintained at approximately Torr, high frequency power of IKW to 1.5 KW is applied, and the substrate holder is heated to maintain the porcelain substrate set at 300° C. to 400° C., and sputtering is performed for 1 hour to 6 hours. Sputtered mental atoms, silicon atoms, carbon atoms, and silicon carbide molecules are heated at 300℃~
It is deposited on the surface of a substrate maintained at 400C to form an amorphous film (1) consisting of tantalum, etc., carbon, and silicon.

The process of atoms adhering to the substrate surface and stacking up at a medium temperature range of 300°C to 400°C is an amorphous state with no crystallinity, and spectroscopic analysis shows that tantalum, etc., carbon, silicon, and the impurity oxygen. Only the spectrum unique to each atom is detected, and the spectrum of silicon carbide is not detected. In order to form an amorphous film (1), it is preferable to set the temperature of the substrate to 300°C to 400°C. After sputtering, nitrogen gas is introduced into the apparatus, and after cooling, the pressure is returned to atmospheric pressure and the substrate is taken out.

Tantalum plate placed on the target (20x50x2t)
The table below shows the relationship between the number of tantalum plates and the resistance value of the film (1), and the resistance value decreases rapidly as the number of tantalum plates increases. The untreated resistance value without heat treatment is preferably expressed in Ω as described below, and the proportion of tantalum on the target is 5 to 40% by weight (at this time, silicon carbide is 6% by weight).
It has been learned that it is sufficient to set the content to a range of 0 to 95% by weight. Especially when tantalum is 10% by weight, silicon carbide is 90%
It has also been found that % by weight is preferred.

Next, heat treatment will be explained. Figure 3 shows the heat treatment profile; the temperature was raised at a rate of IC/sec up to 300C, then the temperature was raised at a rate of 600 c/H until it reached the heat treatment temperature, and the treatment temperature was 600C for 60 minutes. The structure of the amorphous film (1) is controlled. Temperature drop is 400C
It is carried out at a rate of 1C/sec until the temperature reaches 150C, and it is taken out. During heating, argon gas of 10 HP or less is introduced. As shown in Table (4), the resistance value increases slightly with heat treatment.

Stainless steel electrode caps (2) are fitted to both ends of the heat-treated porcelain base, and lead wires 9 are attached to these. Further, lead wires may be attached in contact with both ends of the ceramic base.

Then, in order to obtain a practical resistance value as a thermistor, the film (1) is helically cut and line grooves (3) are formed, thereby obtaining a resistance value in the range of IOKΩ to IMΩ at 25C. Looking at the resistance values of the four tantalum plates shown in Table (4) after heat treatment at 600C, there is a range of about 10%, but the desired resistance value can be manufactured with good reproducibility by helical cutting. In order to protect the coating (1) from contamination due to the atmosphere in which it is used, the substrate is coated with a heat-resistant coating (4) such as silicone or glass.

FIG. 2 shows the temperature/resistance characteristics of the temperature-sensitive resistor produced in this manner. It is understood that it has excellent resistance characteristics in a high temperature range of 150 C or higher (high temperature for a thermistor).

It is a characteristic diagram when the ratio on the target is 10% by weight of tantalum and 90% by weight of silicon carbide.

Furthermore, when used continuously for i, ooo hours at an ambient temperature of 300C, the resistance value change is less than ±1%, and the reliability is extremely high. This is because the structure is stabilized by heat treatment.

(Effects) As described above, the present invention sets and maintains the temperature of the porcelain substrate in an intermediate temperature range of 300T:' to 400C in an inert gas atmosphere, and uses a sputtering method to coat the surface with a non-metallic material made of carbon, silicon, mental material, etc. Forms a crystalline film (1) at 400℃~8
Since heat treatment is performed within the range of 00C for a predetermined time, it is possible to provide a temperature-sensitive resistor suitable for practical resistance value (compatibility with a processing circuit) as a thermistor. Conventional silicon carbide 6
Compared to thermistors manufactured by sputtering deposition at high temperatures above 001:', which have a polycrystalline film of silicon carbide and whose conduction mechanism is based on lattice defects, they have a very high resistance value. In the present invention, since the mental atoms of the amorphous film (1) mainly participate in conduction, it is possible to obtain a desired resistance value with good reproducibility by controlling the mixing ratio. In addition, by helical cutting, a thermistor with small resistance value tolerance can be obtained. As for the manufacturing method, existing resistor production lines can be used, and a thermistor with excellent heat resistance can be provided at low cost.

[Brief explanation of the drawing]

The drawings show an example of the implementation of the present invention, and FIG. 1 is a perspective view, FIG. 2 is a temperature/resistance characteristic diagram, and FIG. 3 is a profile diagram of heat treatment. 1... Film 2... Electrode cap 3
...Line groove 4 ...Heat-resistant coating film patent applicant Miyagawa Dengu Co., Ltd. Figure 2 Turtle 1 (・C)

Claims (6)

[Claims] (1) In an inert gas atmosphere, one or more of tantalum, nickel, chromium, iron, etc. and silicon carbide are simultaneously sputtered to form an amorphous material made of silicon, carbon, tantalum, etc. on the surface of a porcelain substrate. formed by forming a film,
Temperature-sensitive resistor. (2) 50 to 90% by weight of silicon carbide, 50% of tantalum, etc.
The temperature-sensitive resistor according to claim 1, which is sputtered at a rate of ~10% by weight. (3) The temperature-sensitive resistor according to claim 2, wherein the temperature of the ceramic substrate is maintained in a medium temperature range of 400° C. or less during sputtering. (4) The temperature-sensitive resistor according to claim 2, wherein electrode caps are fitted or electrodes are brought into contact with both ends of the base body on which an amorphous film is formed. (5) An amorphous film made of one or more of tantalum, nickel, chromium, iron, etc., carbon, and silicon is formed on the surface of the porcelain substrate in an inert gas atmosphere by sputtering vapor deposition. , followed by heat treatment at a predetermined temperature. (6) The temperature sensor according to claim 5, wherein a practical resistance value is obtained by heat treatment in a range of 400°C to 800°C in an inert gas atmosphere and by helically cutting the formed amorphous film. Method of manufacturing a resistor.