JPS6041441B2 - thin film thermistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermistor, and particularly to a thin film thermistor comprising an electrode film and a temperature-sensitive resistor film formed on an insulating substrate.

This type of thin film thermistor is made of W, Si or Fe.
Temperature-sensitive resistor films made of composite metal oxides such as , Ni, Co, and Mn have been used.

Thermistor constants of these temperature-sensitive resistor films (hereinafter simply referred to as B
(referred to as a constant) was almost constant regardless of temperature, similar to the bulk thermistor made of temperature-sensitive scale aggregates of the composite oxide. Therefore, when this type of thermistor is used as a circuit element in the electric circuit shown in Figure 1 to electrically detect temperature, the output voltage does not vary linearly with temperature, or the detection sensitivity increases with temperature. The disadvantage was that it fluctuated. In FIG. 1, numeral 1 is a thermistor whose resistance-temperature characteristic is indicated by R(T). 2 is the resistance value Ro (constant)
3 is a power supply of voltage EaV, 4 is an output voltage, and its value is indicated by Eg.

The following equation holds true between these. Eg-Ro Ea-Ro+Rbi) Below, we will use Ea=IV for simplicity, but Ea
It will be clear that no essential difference arises in the case of Ki IV.

Ro is the thermistor resistance value R(T
o) is selected to be the same value. To is determined by the detection temperature range, the characteristics of the electric circuit that electrically processes the output voltage Eg, etc. Figures 2 and 3 show the typical relationship between output voltage g and temperature T for conventional thermistors.
The relationship between detection sensitivity excess g/dT and temperature T is shown for the case where To=150°C.

Curves 5 and 7 are for B=200 and K curves 6 and 8 are for B=500 and K. As shown in curves 5 and 6, the output voltage E
g changes in a curve with respect to temperature T. Also curves 7 and 8
As shown in the figure, the detection sensitivity g/dT varies greatly with respect to the temperature T. Due to the output voltage characteristics and detection sensitivity characteristics with respect to the temperature T, disadvantages arise such as the electronic circuit for processing the output voltage g becoming complicated and the circuit design becoming unsatisfactory.

Furthermore, if you want to control the amount of heat generated by a heat source by detecting degrees with a thermistor and comparing it with a set temperature, the electric circuit is usually configured so that the set temperature corresponds to the rotation angle of the rotary shaft of the variable resistor. .

At this time, due to the output voltage characteristics and detection sensitivity characteristics as described above, there was a drawback that the set temperature could not be determined linearly based on the rotation angle. In the region of low detection sensitivity, the temperature T
Since the change in output temperature Eg is in a flat region,
If a slight change occurs in the set rotation angle of the variable resistor, that is, if a slight change occurs in the set output voltage Eg, a large temperature fluctuation will occur.On the other hand, in a region with high detection sensitivity, the opposite is true. . As described above, there is a drawback that the accuracy of the set temperature varies depending on the set temperature. Note that when a SIC resistor film is used as the temperature-sensitive resistor film, the B constant has temperature dependence and is not necessarily constant.

However, even in this case, as shown in curves 9 and 10 in FIGS. 2 and 3, the above-mentioned drawbacks could not be avoided.
The present invention provides a new thermistor that eliminates the drawbacks of these conventional types. The gist of the present invention is a thin film thermistor comprising an electrode film and a temperature-sensitive resistor film formed on an insulating substrate, in which at least the temperature-sensitive resistor film is a laminated film of a plurality of resistor films having different resistance temperature characteristics. At a certain point.

An example of a cross-sectional view of the thermistor of the present invention is shown in FIG.

Reference numeral 11 denotes an insulating substrate, which is made of ceramic such as alumina, mullite, or steatite, or glass such as quartz or citric acid glass.

12 is an electrode film, Au-Pt, Ag-Pd, Au-Pd
, Ag, etc., Cr-Au, Cr-Cu, C
A thin film electrode film such as r-Ag is used.

Both 13 and 14 are temperature-sensitive resistor films, but their resistance-temperature characteristics are different.

The number of laminated resistor films may be two or more. FIG. 4 shows a cross section of the thermistor structure in the case of two layers. Example 1 A Cr4Au thin film electrode plate 12 was formed on one surface of a shelf citric acid glass substrate 11.

Next, using a summer air evaporation equipment, the degree of vacuum was 5 x 10-6 tons or less, the substrate temperature was 300°C, and the evaporation source temperature was 1400 to 1500.
00, evaporation rate 20-5 o/sec, deposition time 100
A Ge temperature sensitive resistor film 13 (approximately 20 mm) was formed on the substrate under conditions of ~20 $ec. After this, using a high-frequency sputtering device, the target SIC composite body, the substrate temperature was 300 oo, and the sputtering pressure (~gas) was 2×10-2 to
rr, high frequency power is W, sputtering time is d. S under the condition of
The IC temperature sensitive resistor film 14 was formed to a length of about 21 m. Output voltage Eg of the thermistor formed in this way, detection sensitivity rudder g
The relationship between /dT and temperature T is shown in Figures 2 and 3, curve 15 and curve 16.
Shown below. As is clear from the figure, the output voltage Eg is 0 to 24
It varied linearly over a wide temperature range of 0 qo. In addition, in the same temperature range, the detection sensitivity g/dT is 1.91 soil 0.
．． It was 13 hV/°C/V, which was almost constant. The Q temperature sensitive resistor film has a specific resistance of approximately 800 pK (constant) at 50 qo, and the B constant has a temperature dependence of approximately 30 pK (constant) at the same temperature. The B constant in the low temperature range (50 to 140 qC) was approximately 1000 K, and the B constant in the high temperature range (140 to 230 qC) was approximately 150 K.

By stacking resistors with different resistance-temperature characteristics in this way, the output voltage Eg can be varied linearly with respect to the temperature T over a wide temperature range, and the detection sensitivity curve g/
dT can be kept constant. In this example, the detection sensitivity was approximately 1.9 hV/.

0, which is a relatively small value, but in practice this level is within a range that can be easily detected electrically.

Furthermore, this embodiment has been described using a Q temperature-sensitive resistor film and a SIC temperature-sensitive resistor film.

However, the overflow sensitive resistor film of the present invention is made of Q, Sj, SIC or metal oxides, such as composite metal oxides such as Fe, Nj, Co, Mn, or Nj, Zn, Cu. Fe,
It is clear that a resistor film in which a plurality of resistor films selected from the group of elemental metal oxides such as Sn and Ba are layered laterally may be used. In addition, as in this embodiment, there are temperature-sensitive resistors other than SIC, such as the e-temperature-sensitive resistor film 13 and the SIC temperature-sensitive resistor.
In the case of a resistor film in which the film 14 and the film 14 are sequentially laminated, the following advantages also occur.

That is, among various temperature-sensitive resistor films, SIC temperature-sensitive resistor films not only have excellent thermal stability but also are extremely chemically stable. Therefore, as shown in this embodiment, by sequentially laminating the Pleasant Temperature Resistor Film 13 and the SIC Temperature Resistor Film 14 in this order, the SIC Temperature Resistor Film 14 can be replaced with the Q Temperature Resistor Film 14. It can be made to act as a protective film for 13. For example, after forming the temperature sensitive resistor films 13 and 14, the Cr-Au thin film electrode film 12 is formed on the entire surface of the temperature sensitive resistor 14, and then the Cr-Au thin film box electrode film 12 is formed into an appropriate shape. Unnecessary Cr-Au
The thin film electrode films 1 and 2 may be chemically corroded and removed. Aqua regia is often used as a chemical etchant for Au. However, aqua regia also corrodes the axle, so it is not desirable. On the other hand, Sic is chemically stable to aqua regia. Therefore, when the SIC temperature-sensitive resistor film 14 protects the pleasurable temperature-sensitive resistor film 13 as in this embodiment, it is extremely safe even against the chemical treatment described above. Example 2 An Au--Pt thick film electrode film 12 was formed on one surface of an alumina substrate 11.

Next, using a high frequency sputtering device, target SIC composite body, substrate temperature 70000, sputtering pressure (~ gas) 2 × 1
Under the conditions of 0-2 tons and high frequency power W, the first one is r.
s. to form a low resistivity/low B constant SIC temperature sensitive resistor film 13, and then further water rs. High resistivity/high B constant SIC
A fringe-sensitive resistor film 14 was formed. SIC temperature sensitive resistor film 13
, 14 had a total film thickness of approximately 4 mm. Output voltage Eg and detection sensitivity dEg/of the thermistor formed in this way
The relationship between dT and temperature T is shown in curves 17 and 18 in Figures 2 and 3. As is clear from the figure, the output pressure Eg is 0 to 2470.
varied linearly over a wide temperature range. Moreover, the detection sensitivity was 1.89-0.1 traces V/°C/V in the same temperature range, and was constant. In addition, low resistivity and low B constant S
The IC temperature-sensitive resistor film 13 has a specific resistance of about 30 mm at 50 mm, and a B constant that is temperature dependent, and has a specific resistance of about 30 mm at 50 mm.
40 CO) and approximately 100 piK, high temperature range (140 to 23
150 K at 0:00), while high resistivity and high B constant SI
C temperature-sensitive resistor waist 14 has a specific resistance of about 1300- at the same temperature.
The B constant has temperature dependence, and is about 23 in the same low temperature region.
0 pK, and about 290 pK in the same high temperature range. Furthermore, when laminating the low resistivity/low B constant SIC temperature sensitive resistor film 13 and the high specific resistance/high B constant SIC temperature sensitive resistor film 14, the order is reversed to that of this embodiment. Of course, this is the case. In the case of the embodiment, since temperature-sensitive resistors having the same composition and different resistance-temperature characteristics are laminated, the thermistor has the advantage of being easy to manufacture.

Note that it is obvious that the advantage that the SIC temperature-sensitive resistor is chemically stable is fully exhibited in this example as well.
As described above, it is clear that the thermist according to the present invention can overcome the drawbacks of the prior art. Furthermore, although the above description has been made in detail through Examples 1 and 2, it is of course possible to use temperature-sensitive resistor elements having other compositions within the scope of the gist of the present invention.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing an example of an electric circuit that electrically detects temperature using a thermistor, Figure 2 is a characteristic diagram showing the relationship between temperature and output of the electric circuit shown in Figure 1, and Figure 3 is a diagram showing the relationship between temperature and output of the electric circuit shown in Figure 1. The figure is a characteristic diagram showing the relationship between temperature and detection sensitivity of the same electric circuit, and FIG. 4 is a sectional view of the thin film thermistor of the present invention. 11... Insulating substrate, 12... Electrode film, 13 and 14...
- Temperature-sensitive resistor films with different resistance-temperature characteristics. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A thin film thermistor comprising an electrode film and a temperature-sensitive resistor film formed on an insulating substrate, in which at least the temperature-sensitive resistor film is formed by laminating a plurality of resistor films having different resistance temperature characteristics. A thin film thermistor characterized by: 2. The thin film according to claim 1, wherein at least the temperature-sensitive resistor film is a laminated film of a plurality of resistor films selected from the group of Ge, Si, SiC, and metal oxides. thermistor. 3 At least, the temperature-sensitive resistor film is a resistor film in which one or more composite resistor films selected from the group of Ge, Si, and metal oxides and a SiC resistor film are sequentially laminated. A thin film thermistor according to claim 1, characterized in that: 4 At least, the temperature-sensitive resistor film is a resistor film in which a SiC resistor film with low resistivity and low thermistor constant and a SiC resistor film with high resistivity and high thermistor constant are laminated in sequence or in reverse order. Claim 1 characterized in that
Thin film thermistor described in Section 1.