JPS6044802B2 - Manufacturing method of thin film thermistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a thin film thermistor, particularly a thin film thermistor using a SiC temperature sensitive resistor film.

Conventionally, SiC temperature-sensitive resistor films are produced by using a SiC sintered body target in Ar gas or Ar gas containing a certain amount of impurities.
It was formed on the substrate by sputtering vapor deposition while heating and holding the substrate at a constant temperature. However, in the thermistor using the SiC temperature-sensitive resistor film formed in this way,
It had the following drawbacks. That is, when a thermistor made of this phase βIC temperature-sensitive resistor film is used as a circuit element of the electric circuit shown in FIG. 1 to electrically detect temperature, the output voltage does not change linearly with temperature. Another disadvantage is that the detection sensitivity varies widely depending on the temperature.

In FIG. 1, 1 is a thermistor, and its resistance-temperature characteristic R(T) is shown.

2 is a fixed resistor with a resistance value Ro (constant), 3 is a voltage EaV
4 is the output voltage, and its value is indicated by Eg.

The following equation holds true between these. -Ro Ea-Ro+R(T) Below, for the sake of simplicity, it will be treated as Ea IV, but E
It will be clear that in the case of a:IV no essential difference occurs.

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, and the like. Figures 2 and 3 show conventional SiC
Regarding the temperature-sensitive resistor film, the typical relationship between the output voltage Seg and temperature T, and the relationship between detection sensitivity DEg/DT and temperature T are as follows: TO=1
The case where the temperature is 50°C is shown.

As shown in curve 5, the output voltage Eg changes in a curved manner with respect to the temperature T. Also, as shown in curve 6, the detection sensitivity D
Eg/DT varies widely with respect to temperature T. These output voltage characteristics and detection sensitivity characteristics with respect to temperature T have resulted in drawbacks such as the complexity of the electronic circuit for processing the output voltage g and the difficulty of circuit design.

Furthermore, if you want to control the amount of heat generated by a heat source by detecting the temperature 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, there was a drawback that the set temperature could not be determined linearly with respect to the rotation angle due to the output voltage characteristics and detection sensitivity characteristics as described above. In the region where detection sensitivity is small, the change in output voltage Eg with respect to temperature T is flat, so if a slight change occurs in the set rotation angle of the variable resistor, that is, there is a small change in the set output voltage Eg. If this occurs, large temperature fluctuations will occur, while in regions of high detection sensitivity the opposite is true. As described above, there was a drawback that the accuracy of the set temperature varied depending on the set temperature. To overcome these drawbacks, the resistance temperature characteristics must be changed.

However, this has been difficult with the conventional sputtering deposition method for SiC temperature sensitive resistor films. That is, a SiC temperature-sensitive resistor film formed by sputtering deposition under specific conditions has an inherent resistance temperature characteristic determined by the specific formation conditions.
Therefore, the above-mentioned drawbacks could not be overcome. The present invention provides a novel method for manufacturing a SiC temperature-sensitive resistor film that eliminates these drawbacks of conventional SjC temperature-sensitive resistor films. The gist of the present invention is to sputter a SiC temperature-sensitive resistor film. In the method of forming on a substrate by ring evaporation, at least the substrate is heated and maintained at a constant temperature, and a SiC sintered target is sputtered for a certain period of time in Ar gas containing a certain amount of impurity gas I, Further, Ar gas contains a certain amount of an impurity gas I of the same type as the impurity gas, or A contains a certain amount of an impurity gas different from the impurity gas.
The target is sputtered for a certain period of time in r gas to form Si.
C. The point is to form a temperature-sensitive resistor film.

The resistance-temperature characteristics of a SiC temperature-sensitive resistor film are greatly affected by the type and concentration of impurity gas contained in the sputtering atmosphere (usually Ar gas).

FIG. 4 shows an example where the impure gas is N2 or CO2.
As shown in the figure, both the resistance value and the B constant can be controlled over a wide range by adding N2 gas and CO2 gas. Example 1 An alumina substrate on which an Au-Pt thick film electrode film was formed was placed in a k-high frequency sputtering device, and the substrate temperature was 650°C, and
A SiC sintered target (224 angle, thickness 6Tn!n) was sputtered for 4 hours in K gas containing 0.4V01% N2 gas, and then SiC was continuously sintered in K gas containing 3V01% N2 gas. I sputtered two body targets.

At this time, the sputtering power is 2KW, and the sputtering gas pressure is 2KW.
．． The distance between the 5x10-2t(1)Rrl target and the substrate was about 307 m. SiC formed in this way
The output voltage characteristics and detection sensitivity characteristics of the resistor film are shown in Figures 2 and 3.
Figure 7 shows curves 7 and 8.

As is clear from these figures, the output voltage Eg is O~2
It varied linearly with temperature T over a wide temperature range of 40°C. The detection sensitivity in the same temperature range is 1.9±0.
It was 13 mV/°C, which was almost constant. In the manufacturing method of the present invention, when forming an SlC temperature-sensitive resistor film by a sputtering vapor deposition method as in this embodiment, N containing impurity gas is used.
The target is sputtered in a gas, and the impurity gas concentration is changed during the process.

Therefore, the SiC temperature sensitive resistor film formed on the substrate has a structure in which two layers of SiC temperature sensitive resistor films having different resistance temperature characteristics are laminated. As a result, output voltage characteristics and detection sensitivity characteristics that could not be obtained with conventional sputtering deposition methods can be obtained. As impure gas I, 02, N2,
The gas may be one or more mixed gases selected from the group of C0 and C02.

The influence of these impure gases on the resistance-temperature characteristics of the SiC temperature-sensitive resistor film varies depending on the type and concentration of the gas, but CO
, CO2 show almost similar trends, and N2 and O2 also show almost similar trends. Example 2 A quartz substrate on which an Au-Pt thick film electrode film was formed was placed in a high-frequency sputtering device, and the substrate temperature was 750°C and CO
A SiC sintered target (224 mm square, 67 r0n thickness) was sputtered for 7 hours in Ar gas containing 0.4 V01% of 2 gas, and then CO2 gas was continuously adjusted to 0 V01%, and at the same time 02:N2 = 1: 4 (volume ratio) mixed gas at 2V
A SiC sintered target was sputtered in a N gas containing 0.01%.

At this time, the sputtering power was 2KW, the sputtering gas pressure was about 2.5.times.10@-2 t0rr, and the distance between the target and the substrate was about 3". The output voltage characteristics and detection sensitivity characteristics of the SiC resistor film formed in this way are shown in Figures 2 and 3.
It was similar to curves 7 and 8. The structure of the SiC temperature-sensitive resistor in this example is the same as that in Example 1. It goes without saying that the type and concentration of the impurity gas I may be different from each other as shown in this embodiment.

Further, the concentration of impurity gas is preferably 5V01% or less.

This is true for SiC in the region of impurity gas amount of 5v01% or more.
This is because both the specific resistance value and the B constant of the temperature-sensitive resistor rapidly increase, making it no longer practical to use as a resistor. Although the details of this cause are unknown, in this region, as a result of the reaction between the impurity gas and SiC in the sputtering deposition process, the reactants, such as Si oxide and Si nitride, are formed in the formed SiC temperature sensitive resistor. This is thought to be due to the contamination of Further, when sputtering the SiC temperature-sensitive resistor, the substrate temperature is preferably 500° C. or higher.
This is because it is practically easy to increase the long-term heat resistance of the SiC temperature-sensitive resistor to 250° C. or higher if the substrate temperature is higher than this. As is clear from the above description, the manufacturing method of the present invention can easily form a characteristic SiC temperature-sensitive resistor film, which has been difficult with conventional manufacturing methods.

Although detailed explanations have been made through the examples, types of impurity gases other than those in the examples may be used as long as they are within the gist and scope of the present invention.
Of course, the concentration and substrate temperature may also be used.

[Brief explanation of the drawing]

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 diagram showing the relationship between impure gas concentration, resistance value, and B constant during sputtering. 1...Thermistor, 2...Fixed resistor, 3...Power supply.

Claims (1)

[Claims] 1. A method for forming a SiC temperature-sensitive resistor film on a substrate by sputtering deposition, in which at least the substrate is heated and maintained at a constant temperature, and SiC sintering is performed in Ar gas containing a certain amount of impurity gas. sputtering the body target for a certain period of time, and further sputtering the target for a certain period of time in Ar gas containing an impurity gas of the same type as the impurity gas in a certain amount different from the certain amount, or in Ar gas containing a certain amount of impurity gas different from the impurity gas. A method for manufacturing a thin film thermistor, comprising forming a SiC temperature sensitive resistor film. 2 At least impure gas O_2, N_2, CO, CO
2. The method for manufacturing a thin film thermistor according to claim 1, wherein the gas is one or more mixed gases selected from the group _2. 3 At least, the amount of impure gas is 5 vol%, which is more than O.
A method for manufacturing a thin film thermistor according to claim 2, characterized in that: 4 Claim 1, characterized in that the SiC temperature-sensitive resistor film is formed at least at a substrate temperature of 500°C or higher.
A method for manufacturing a thin film thermistor as described in Section 1.