JP3366590B2 - Temperature measuring device, thermal infrared image sensor and temperature measuring method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature measuring device, a thermal infrared image sensor and a temperature measuring method. The present invention particularly relates to a temperature sensor in which a bipolar transistor or a MOS transistor operated as a bipolar transistor is regarded as a thermistor, and a temperature measuring method. Furthermore, the present invention is used in a temperature sensor unit such as a temperature distribution detection of an integrated circuit, a flow sensor, a Pirani vacuum gauge, a thermal infrared sensor, a thermal infrared thermometer, and a thermal infrared image sensor.

[0002]

2. Description of the Related Art Conventionally, a thermistor has been known as a temperature sensor. The temperature dependence of the thermistor resistance is
Determined by the thermistor constant (B constant). The B constant is a constant when expressing the temperature (T) dependence of the thermistor resistance R, and is expressed by the following equation. Here, the resistance Ro is the resistance when the temperature T = To, and the resistance R
in is the resistance when the temperature T is infinite. This means that the B constant and the resistances Ro and Rin are determined by the thermistor, and the thermistor resistance R (T) is a straight line on a semilogarithmic graph when the reciprocal of the temperature T is plotted on the horizontal axis. Therefore, the B constant has a unit of K, and an ordinary thermistor has a value of about 4000K, and a larger one has a higher sensitivity.

Here, for example, when replacing a defective thermistor, it is conventionally difficult to obtain a thermistor whose B constant is exactly the same. Therefore, a thermistor having a close B constant is selected, and the thermistor is connected in series or in series. A resistor was connected in parallel to approximate the original thermistor. The present inventor has invented a temperature compensation method for the thermistor as a method for making the B constants of an actual thermistor circuit-wise coincide (Japanese Patent Application No.
-324683). There, four thermistors were assembled in a Wheatstone bridge and an OP amplifier was used to
The equivalent match of the constant was made.

Further, conventionally, a temperature sensor utilizing a semiconductor pn junction has been developed, which is called a diode temperature sensor. The diode temperature sensor is p
Temperature dependence of forward rising voltage of the n-junction diode, that is, forward voltage Vf when a constant current flows
Is used in proportion to the temperature (absolute temperature) T at that time.

Other temperature sensors using a semiconductor pn junction are also called transistor temperature sensors. Like the diode temperature sensor, the transistor temperature sensor has a pn junction between the emitter and the base of the bipolar transistor. Therefore, when the forward-direction emitter-base voltage Ve keeps the collector current constant, it is almost the same. This is because it is proportional to the temperature T.

Further, the present applicant invented the Schottky junction temperature sensor, and the temperature dependence of the reverse current when the reverse bias of the Schottky barrier diode is specified is just like the temperature dependence of the thermistor. Showed that it can be used as a thermistor (Japanese Patent Application No. 3-284266).
reference). Further, the barrier height of the Schottky barrier diode corresponds to the equivalent B constant of the thermistor, and the barrier height of the Schottky barrier diode is almost determined if the type of semiconductor and the type of Schottky metal are determined. It was shown that there is a characteristic that the B constant is fixed if a Schottky barrier diode is created, and it was named and proposed as a Schottky barrier thermistor (for example, Schott
ky Barrier Thermistor; 11t
h Sensor Symp. 1992, see).

[0007]

However, in the conventional thermistor as a temperature sensor, the compatibility of the thermistor has been a problem. For example, when a thermistor with a close B constant is selected and a resistor is connected in series or in parallel to it to approximate the original thermistor, the thermistor having exponential temperature dependence of the resistance value has a temperature dependence. Even if you connect a resistor that has almost no, it will be essentially different. Further, the temperature compensation method of the thermistor which is the above-mentioned invention of the present applicant requires at least three OP amplifiers,
There was also a problem that two other thermistors were needed to match the B constants of the two thermistors.

Further, in the conventional diode temperature sensor and transistor temperature sensor, forward voltages Vf and V of the pn junction in a state where a constant current is made to flow respectively.
The temperature dependence of e is used, and its output is advantageous in that it is proportional to the absolute temperature T. However, for example, when a silicon semiconductor is used, the forward-direction rising voltage itself is about 0.65 V at most, so it depends on the temperature change. Forward voltage Vf
Alternatively, there is a problem that the output voltage of the temperature sensor itself, which is a change amount of Ve, is extremely small.

Also in the Schottky barrier thermistor, even if the type of semiconductor and the type of Schottky metal are actually determined, the difference in the fabrication temperature of the Schottky barrier diode, the difference in the leak current in the reverse direction, and the application in the reverse direction of operation. There is a problem that the B constant is slightly different due to the difference in voltage, and the voltage applied to the Schottky barrier thermistor which is a Schottky barrier diode is specified so that a large voltage cannot be applied, resulting in a small output and a small SN. was there.

The present invention is a kind of transistor temperature sensor, but one transistor temperature sensor is configured so that it can be considered equivalent to one thermistor, and the equivalent B constant is finely adjusted. It is an object of the present invention to provide a transistor thermistor capable of applying a large voltage and obtaining a large output. Another object of the present invention is to provide various devices using the same.

Here, the transistor thermistor means a device in which a transistor is treated as a thermistor. Further, the B constant is considered to correspond to, for example, the activation energy of the semiconductor, and the transistor thermistor makes this idea correspond to, for example, the activation energy (potential difference) due to the potential barrier between the emitter and the base of the pn junction. You can think of it as something.

[0012]

According to a first solution of the present invention, a bias circuit for outputting a first voltage and the output of the bias circuit are applied between the emitter and the base as a forward bias voltage. , A transistor having a collector to which a second voltage is applied and having a collector current as an output, and the temperature dependence of the collector current with respect to the collector voltage of the transistor is such that the collector resistance of the transistor is regarded as a thermistor. The transistor is used so as to correspond to temperature dependence, and the forward bias voltage is adjusted by adjusting the output voltage value of the bias circuit. The forward bias voltage causes the potential barrier between the emitter and the base of the transistor. By adjusting the height, the temperature dependence of the collector resistance of the transistor can be measured. The thermistor constant to provide a temperature measuring device can be adjusted to a desired value.

According to the second solving means of the present invention, the bias circuit for outputting the first voltage and the output of the bias circuit are applied between the source and the gate as the bias voltage, and the second voltage is applied to the drain. A MOS type or other field effect transistor that outputs a drain current applied thereto, operates the field effect transistor so as to correspond to a bipolar transistor in its subthreshold, and drains the field effect transistor with respect to a gate voltage. The field effect transistor is used so that the temperature dependence of the current corresponds to the temperature dependence of the current when the drain resistance of the field effect transistor is regarded as a thermistor, and the output voltage value of the bias circuit is adjusted. Adjust the bias voltage or the voltage in the channel formation region, By adjusting the potential barrier height between the source and drain of the field effect transistor by an ass voltage, a temperature that allows the thermistor constant representing the temperature dependence of the drain resistance of the field effect transistor to be adjusted to a desired value. A measuring device is provided.

According to a third solution of the present invention, there is provided a thermal infrared image sensor in which a plurality of temperature measuring devices as described above are arranged in a matrix and the output of each of the temperature measuring devices is read out. provide.

According to the fourth solution of the present invention, the first voltage is output from the bias circuit, the output of the bias circuit is applied between the emitter and the base as the forward bias voltage of the transistor, and the first voltage is applied to the collector. The voltage dependence of the collector current of the transistor with respect to the collector voltage of the transistor is equivalent to the temperature dependence of the current when the collector resistance of the transistor is regarded as a thermistor. By using a transistor, the forward bias voltage is adjusted by adjusting the output voltage value of the bias circuit, and the potential barrier height between the emitter and the base of the transistor is adjusted by the forward bias voltage. The thermistor constant, which represents the temperature dependence of the collector resistance, can be adjusted to the desired value Providing Unishi was temperature measurement method.

According to the fifth solution of the present invention, the first voltage is output from the bias circuit, and the output of the bias circuit is applied between the source and the gate as the bias voltage of the MOS type or other field effect transistor. Then, a second voltage is applied to the drain, the drain current is output, and the field effect transistor is operated so as to correspond to a bipolar transistor in its subthreshold,
The bias circuit is formed by using the field effect transistor such that the temperature dependence of the drain current with respect to the gate voltage of the field effect transistor corresponds to the temperature dependence of the current when the drain resistance of the field effect transistor is regarded as a thermistor. The bias voltage or the voltage of the channel forming region is adjusted by adjusting the output voltage value of the field effect transistor.
A temperature measuring method is provided in which the thermistor constant representing the temperature dependence of the drain resistance of the field effect transistor can be adjusted to a desired value by adjusting the height of the potential barrier between the drains.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION (1) Operating Principle and Outline In a transistor thermistor according to the present invention, the temperature dependence of collector current with respect to a predetermined collector voltage of a bipolar transistor is exactly the same when the bipolar transistor is regarded as a thermistor. It is based on the agreement with the temperature dependence.

The B constant of the thermistor corresponds to the height of the potential barrier between the emitter and base of the bipolar transistor in the transistor thermistor. Therefore, the present invention provides a transistor thermistor capable of adjusting the potential barrier height between the emitter and the base by adjusting the emitter-base voltage Ve in the forward direction so that the desired B constant can be adjusted. is there.

Collector current I of bipolar transistor
c is near room temperature (T = 300K), and Ve, Vc> 0.
If it is 1 V, it is represented as the following equation as a very good approximation equation. Ic = I ₀ exp {−q (Vd−Ve) / nkT} where I ₀ corresponds to the collector current when the temperature T is infinite, Vd is the diffusion potential of the emitter-base pn junction, and q , K and n are the elementary charge, the Boltzmann constant and the ideal coefficient, respectively. The ideal coefficient n is 1 in a bipolar transistor having excellent single-crystal characteristics, whereas it is 1 in a bipolar transistor using a polycrystalline semiconductor.
Deviation from the ideal transistor, n is, for example, a constant in the range of 1.1 to 1.7, which is determined at the time of creation. Also,
(Vd-Ve) is the height of the potential barrier between the emitter and the base.

Further, the collector resistance Rc when the collector voltage Vc is fixed is expressed as Rc = Vc / Ic = R ₀ exp {q (Vd-Ve) / nkT} = R ₀ exp {B / T}. . Here, R ₀ (= Vc / I ₀ ) corresponds to the collector resistance Rc when the temperature T is infinite, and q (Vd−V)
Considering e) / nk as the B constant of the thermistor, Rc is
Negative Temperature Coefficient, NT
It can be seen that it can be handled in the same way as the C) thermistor (NTC thermistor).

In reality, the collector current Ic is a minute base-collector reverse leakage current I that is insensitive to temperature.
_CEO is included, but since it is generally small enough to be ignored, Ic may be left as it is in the above equation, but if it is large enough not to be ignored, temperature dependence is taken into consideration instead of (Ic -I _CEO ).

From the above consideration, it is understood that the potential barrier height (Vd-Ve) between the emitter and the base corresponds to the B constant of the thermistor except for the Boltzmann constant k. The diffusion potential Vd is determined by making a bipolar transistor, but by adjusting the emitter-base voltage Ve, the height of the potential barrier between the emitter and the base can be adjusted to a desired B constant. It can be seen that a transistor thermistor can be provided.

In the above-mentioned conventional transistor temperature sensor, a constant current circuit is provided so that a constant collector current flows through the bipolar transistor, and the emitter-base voltage V, which is the forward voltage of the pn junction between the emitter and the base.
It measures the change of e with temperature. However, its output voltage has the merit of being proportional to the absolute temperature T, but it is extremely small, so it is necessary to amplify it with an amplifier circuit provided separately to obtain an output proportional to temperature. It is common to On the other hand, in the transistor thermistor of the present invention, a circuit is formed so that a forward bias is applied between the emitter and the base and a reverse bias is applied between the base and the collector like a normal bipolar transistor. A desired forward emitter-base voltage V is obtained by dividing the forward bias voltage between the bases from a constant voltage power supply.
By adjusting the emitter-base voltage Ve, the collector resistance Rc regarded as a thermistor has a desired B constant. At this time, since the pn junction between the base and the collector is reverse biased, the collector resistance Rc becomes extremely large and is sufficiently smaller than the collector resistance Rc. However, even a load resistance RL of about 100 kΩ, which is generally regarded as a large resistance, has a collector resistance Rc. According to the present invention, a transistor amplifying mechanism can be used, so that a large output can be obtained.

Further, in the present invention, it has been noted that the MOS transistor can also be operated as a bipolar transistor in its subthreshold. Therefore, according to the present invention, the source, channel, and drain of a MOS transistor are treated as bipolar transistors by making them correspond to the emitter, base, and collector of the bipolar transistor, respectively, so that a desired B constant can be adjusted. To provide. In such a case, the emitter-base voltage V as a bipolar transistor is
e can be adjusted by the gate voltage Vg of the MOS transistor or the voltage Vs of the substrate (the region forming the channel region). Therefore, the MOS transistor can also be a transistor thermistor of a bipolar transistor in the subthreshold region.

In this way, the MOS transistor is
As a bipolar transistor in the threshold
When operated, the drain current ID is I_D= I_0D exp {q (Vg-V_T) / NkT} Is expressed as Where I_0DIs the temperature when the temperature T is infinite
Equivalent to the rain current, V _TIs the threshold voltage
It Also at this time, q (Vg-V_T) / Nk is the thermistor
Considering the B constant of, as described above, the MOS transistor
In the subthreshold, Ta also NTC Sami
It can be seen that it can be handled in the same way as a star.

Further, in the transistor thermistor according to the present invention, a bias circuit is formed in an integrated manner by using the sharing of the resistance of the power supply voltage so that the predetermined emitter-base voltage Ve is obtained when the bipolar transistor is manufactured. You can When the present invention is completed, the desired emitter-base voltage Ve can be obtained without adjustment.
Therefore, it is possible to provide a bipolar transistor capable of obtaining a desired B constant.

Depending on the transistor thermistor according to the present invention, when a bipolar transistor is formed in a thin film semiconductor layer used in a thin film SOI substrate or a thermal infrared sensor having a micro air bridge structure, a normal thickness direction ( It is difficult to form the emitter region, the base region, and the collector region in the vertical direction sequentially, and it is desirable to form these in the horizontal direction. Most of the carriers injected from the emitter region to the base region flow laterally and reach the collector region.

Further, in the present invention, a transistor thermistor can be formed on a polycrystalline silicon thin film so that a bipolar transistor can be formed on an insulating substrate. Further, according to the present invention, a plurality of transistor thermistors can be formed on the same substrate. In this case, the B constants of the plurality of transistor thermistors can be set to be the same by adjusting Ve of each bipolar transistor. For example, two micro air bridges formed on the same silicon substrate and the substrate itself,
Each transistor thermistor is formed and adjusted to the same B constant, and one transistor thermistor on the two micro air bridges is used as an infrared light receiving sensor or the like and the other is used as a temperature compensation element or the like, and the transistor thermistor on the substrate is It can be used for temperature monitoring. By doing so, even if there is a large change in ambient temperature, the temperature of the target can be accurately measured.

It is also possible to examine the temperature distribution on a plane such as an LSI substrate. It is also possible to form a bipolar transistor array by arranging a plurality of transistor thermistors having the same B constants in a vertical connection.

Further, the transistor thermistor of the present invention integrates a constant voltage power supply circuit on the same substrate and utilizes the voltage from the constant voltage power supply circuit to adjust the emitter-base voltage Ve of the bipolar transistor. Can also be In order to set the B constant that determines the temperature dependence of the thermistor to a desired constant value, it is necessary to set the emitter-base voltage Ve to a specific constant value in accordance with the diffusion potential Vd of the created bipolar transistor.
Therefore, it is necessary to apply a constant emitter-base voltage Ve that is not affected by ambient temperature changes, power supply voltage changes, load changes, and the like. For that purpose, for example, when a silicon (Si) substrate is used, it is convenient to integrate a Zener diode for producing a constant voltage and various resistors on this same Si substrate together with a bipolar transistor which serves as a transistor thermistor. . Generally, the constant voltage of the Zener diode is, for example, about 6V, whereas the emitter-base voltage Ve for obtaining a desired B constant is, for example, about 0.50V. Therefore, in order to adjust the voltage, for example, a constant voltage from the Zener diode may be resistance-divided to form and apply the emitter-base voltage Ve that is difficult to change. When there are multiple transistor thermistors,
It suffices to divide the voltage from the individual constant voltage circuits so that the desired emitter-base voltage Ve of each transistor thermistor can be obtained. Note that a plurality of electrically isolated constant voltage circuits may be provided for a plurality of transistor thermistors having no common terminal.

Further, the transistor thermistor of the present invention is a case where a bipolar transistor is formed on a thin film having a cavity in the lower part, the upper part, the lateral part or the like. Such a structure is for thermally separating the bipolar transistor, which serves as the temperature sensing portion, from the substrate and reducing the heat capacity thereof, thereby increasing both the response speed and the sensitivity. Here, “formed on the thin film” does not necessarily mean only on the thin film, but may be formed on the lower part in contact with the thin film. For example, a bipolar transistor serving as a planar type transistor thermistor is formed on a single crystal of silicon, and a bipolar transistor formed on a thin single crystal of silicon is covered with a CVD film such as a silicon oxide film on the bipolar transistor. A cavity may be provided below it so that it can be hung.

Further, the present invention relates to a temperature measuring method in which the above-mentioned transistor thermistor is combined to measure the temperature. A thermal infrared sensor is one of the application devices of the transistor thermistor of the present invention. In this, a thermal thermistor is formed by making a transistor thermistor as an infrared ray receiving section. When the thermal infrared sensor is used as a so-called infrared thermometer for measuring body temperature and the like, for example, two micro air bridges formed on a silicon substrate and a thin film thermistor are formed on the substrate itself. The thermistor formed on the substrate by using one of the two micro air bridges for infrared ray reception and the other for ambient temperature compensation can be used for monitoring the substrate temperature. Since the amount of infrared rays received from temperatures as low as body temperature is extremely small, the temperature difference between the two thermistors for infrared ray reception and ambient temperature compensation of the micro air bridge is extremely small, for example, 0.1 ° C. It is necessary to accurately measure the difference with an accuracy of 3 digits or more. However, if there is a difference in B constant between these thermistors, the change in ambient temperature is extremely large, for example, from 0 ° C. to 35 ° C., so the change in the two thermistor outputs due to the change in ambient temperature is large, resulting in a large error. Will end up. Therefore, if there is no difference in the B constants of the two thermistors as in the present invention, then 2
Since the difference between the two thermistor outputs is the difference only in the amount of infrared rays received from the measured object such as body temperature, the error can be made extremely small.

Another application device of the transistor thermistor of the present invention is a thermal infrared image sensor. In this system, in addition to the transistor thermistor, thermal infrared sensors are arranged in a matrix and the outputs of the thermal infrared sensors are sequentially read. In this case, an array of thermal infrared sensors is arranged in a matrix on each of the XY planes (horizontal-vertical planes), and an infrared lens or a concave mirror is provided on the array to form an optical system for forming images. Each thermal infrared sensor serves as an image pixel. Each bipolar transistor has an emitter
The inter-base voltage Ve can be divided and applied from the stabilized power supply. With such a configuration, it is possible to realize infrared image display as in a television.

Furthermore, the present invention relates to a temperature measuring method in which the above-mentioned transistor thermistor is combined to measure the temperature.

(2) Transistor Thermistor (Temperature Measuring Device) The transistor thermistor of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an example of a basic circuit diagram of a transistor thermistor of the present invention. This transistor thermistor is a schematic diagram using a bipolar transistor 10 which is an npn transistor. In the bipolar transistor 10, the collector-base voltage Vc is reversely biased from the power supply Vcc and the emitter-base voltage Ve is biased forward between the collector C and the emitter E via the load resistance RL as in normal operation. Is applied as described above. Further, the voltage Vz from the stabilized power supply 100 is
The resistors Ra, Rb, and Rk are applied across the series circuit.
The output value from the tap of the resistor Rb can be finely changed so that the emitter of the bipolar transistor 10
The base voltage Ve is forward biased so that a necessary shared voltage can be obtained. Thereby, the bipolar transistor 10 is adjusted to have a desired B constant as a transistor thermistor.

At this time, for example, the power source Vcc is 6V,
The voltage Vz of the stabilized power supply can also be set to 6V or the like. Further, for example, a commercially available npn transistor is used, and the emitter-base voltage Ve is 0.3V, 0.4.
When set to V and 0.5 V, the B constant values were, for example, 11250K, 10250K, and 8750K, respectively.

Thus, the value of the B constant can be finely adjusted by adjusting the emitter-base voltage Ve. This is just regarded as a thermistor having the collector resistance Rc having a negative temperature coefficient, that is, an NTC thermistor, and the value of the B constant can be finely adjusted. The collector current Ic changes according to the change of the temperature T, and the output is taken out as a voltage drop of the load resistance RL. collector·
Since the reverse bias is applied to the pn junction between the bases, the collector resistance is large, and the load resistance RL can be a large resistance such as 100 kΩ to 1 MΩ. The large output impedance is the original amplification mechanism of the bipolar transistor.
Therefore, for example, when the load resistance RL is 1 MΩ and the collector current changes by 1 μA, the voltage drop of RL is 1 V, and a large change in the output voltage V ₀ is obtained.
In order to increase the collector current under the same emitter-base voltage Ve, the junction area may be increased.

FIG. 2 is another basic circuit diagram of the transistor thermistor of the present invention. This circuit is a modification of the basic circuit shown in FIG. 1 of the transistor thermistor of the present invention.
It is a schematic diagram of an embodiment when only one stabilized power supply 100 is used as a power supply. In this circuit, only one power supply (stabilized power supply 100) is required, so the circuit becomes simple. As in FIG. 1, by adjusting the output value of the resistor Rb,
The B constant can be finely adjusted.

FIG. 3 is a cross sectional view of a transistor thermistor having a bipolar transistor formed on a substrate. In this figure, an npn-type bipolar transistor 10 used as a transistor thermistor is formed on an n-type silicon (Si) substrate 1, and a Zener diode 30 and a resistor Rk which serve as a voltage reference for a stabilized power supply 100 are formed. . Further, here, the resistor Rk is used to divide the emitter-base voltage Ve from the stabilized power supply 100, as shown in FIGS.

The resistance Rk is the diffusion resistance layer 41 and the p-type layer 4
2. Equipped with diffusion resistance electrodes 65a and 65b. The bipolar transistor 10 includes an n-type emitter region 20, a p-type base region 21, an n-type collector region 22, an ohmic contact layer 23, an emitter electrode 60, a base electrode 61, and a collector electrode 62. Also, the Zener diode 3
0 includes an n-type layer 31, a p-type layer 32, and electrodes 63 and 64. Note that the oxide film 501 may be formed or may not be formed. In the drawings and the description thereof, the same reference numerals indicate the same components.

This device can be produced, for example, as follows. First, the surface of the n-type Si substrate 1 is thermally oxidized to grow a silicon oxide film 50 of about 0.5 μm. At this time, the oxide film 501 below the substrate may or may not be formed. Then, using a known photolithography technique, a window is opened on the surface of the Si substrate 1, and a p-type impurity (for example, boron) is first added to the depth of about 3 μm by thermal diffusion to form a p-type impurity layer. A p-type layer 32 of the Zener diode 30, a p-type base region 21 of the bipolar transistor 10 and a p-type layer 42 for insulating isolation of diffusion resistance are formed. Next, the Si substrate 1 is further thermally oxidized and a window is opened at a required location,
This time, an n-type impurity (for example, phosphorus) is added by thermal diffusion to a depth of about 1 μm, and the n-type layer 31 of the Zener diode 30, which is an n-type impurity layer, the n-type emitter region 20 of the bipolar transistor 10, the collector, and the like. The ohmic contact layer 23 for the region 22 and the n-type diffusion resistance layer 41 serving as diffusion resistance are formed by an ion implantation technique or the like. After that, thermal oxidation is performed again to open windows for electrodes, and then metallization for wiring is performed, and wirings and diffusion resistance electrodes 65a and 65 are formed.
b, the emitter electrode 60, the base electrode 61, the collector electrode 62, the electrodes 63 and 64 of the Zener diode 30, and pads and the like are formed. The reverse breakdown voltage of the Zener diode 30 is almost determined by the impurity densities on both sides of the pn junction. The higher the impurity density, the smaller the reverse breakdown voltage. For example, as an example, it can be designed to have a reverse breakdown voltage of about 6V. Since the diffusion resistance value is determined by the impurity density of the n-type diffusion resistance layer 41 and its size, the diffusion resistance value Rk is designed to have a desired resistance value (for example, 1 kΩ). As the electrode, a vacuum-deposited film of Si-containing Al or the like which has been conventionally used as an electrode material of a semiconductor device can be used.

FIG. 4 is a cross-sectional view of a transistor thermistor in which a plurality of npn-type bipolar transistors are formed on the same substrate. This figure shows the same p-type Si substrate 1
A plurality of npn-type bipolar transistors 10a, 1
It is a schematic diagram of a transverse sectional view of an embodiment when forming 0b, 10c (part) ,.

The bipolar transistor 10a includes an n-type emitter region 20a, a p-type base region 21a, an n-type collector region 22a, an emitter electrode 60a and a base electrode 61.
a and a collector electrode 62a. The bipolar transistor 10b includes an n-type emitter region 20b, a p-type base region 21b, an n-type collector region 22b, and an emitter electrode 60.
b, a base electrode 61b, and a collector electrode 62b.
A part of the bipolar transistor 10c is shown, and an n-type emitter, a p-type base, and an n-type collector region 22 are shown.
c, an emitter electrode, a base electrode 61c, and a collector electrode. Here, a plurality of n-types are formed on the same p-type Si substrate 1.
Since a pn type bipolar transistor is formed,
The n-type collector regions 22a, 22b, 22c are isolated from each other by a pn junction with the p-type substrate. Each bipolar transistor 10a, 10 on the substrate 1
The manufacturing method of b, 10c, ... Is almost the same as the manufacturing method of the npn-type bipolar transistor 10 shown in FIG.

The present invention can be applied to both npn-type and pnp-type transistors. Further, the present invention can be appropriately applied such that the emitter and the collector of the transistor are used in reverse and the emitter is used as the collector.

(3) A plurality of transistor thermistors is formed FIG. 5 is a circuit diagram including a plurality of transistor thermistors. Three npn-type bipolar transistors 1
0a, 10b, 10c emitter-base voltage Ve
1, Ve2, and Ve3 are adjusted by bias adjusting resistors Rb1, Rb2, and Rb3, respectively, and all three have the same B value.
I made it a constant. The number of transistors here is an example, and can be appropriately provided as needed. Voltage from the power supply _{E B} includes a Zener diode 30 resistor R
The voltage of the Zener diode 30 which is shared by z and is reverse-biased is the voltage Vz of the stabilized power supply 100. For example, the voltage of the power source EB is 7 V, the voltage Vz of the Zener diode 30 is 6 V, the voltage dividing resistors Ra and Rk are 10 kΩ and 2 kΩ, respectively, and the resistors Rb1, Rb2, R
The original value of b3 is both 20 kΩ, load resistances RL1 and RL
Both 2 and RL3 can be operated with 100 kΩ.

FIG. 6 is an explanatory diagram of a case where a plurality of transistor thermistors are applied to a thermal infrared sensor and integrated on a semiconductor substrate. The three npns shown in FIG. 5 above
Two bipolar transistors 10a, 10b, and 10c of the bipolar transistors 10a, 10b, and 10c are formed on the respective Si substrates, and are formed in a thin film on the micro air bridge having the cavity 5 in the lower portion. One bipolar transistor 10a was used as an infrared ray receiving sensor, and the other bipolar transistor 10b was used as a compensating sensor by blocking external infrared rays. Further, the remaining one bipolar transistor 10c was formed on this substrate in order to measure the temperature of the Si substrate 1. In this example,
An example in which almost all are integrated on a semiconductor substrate except the external power supply EB is shown.

The three npn-type bipolar transistors 10a, 10b and 10c are made of extremely thin single crystal Si.
It can be formed (for example, when a part of the Si substrate is left or when it is formed by the SOI technique) or in a polycrystalline silicon thin film on a silicon oxide film. It is convenient that all three are formed by the same process because the characteristics are more uniform and it is easy to set the same B constant. Each resistance R
z, Ra, Rk, RL1, RL2, RL3 and resistor Rb
1, the resistance r12 of the fixed part constituting Rb2, Rb3,
The diffusion resistance of the semiconductor as described above can be used as r22 and r32. Also, the resistors Rb1 and Rb
2, the resistors r11 and r2 of the variable adjustment part that constitute Rb3
As 1, r31, a resistive metal thin film such as nichrome may be patterned on a silicon oxide film on a Si substrate, and the value thereof may be finely adjusted by laser trimming or the like. These transistors, Zener diodes 30, resistors and electrode pads 501, 502, 503;
Among the wirings connecting 511 and 510, the wirings 400, 401 and 4
03, 411, 412, 413, and 430 are aluminum (A) on an insulating film such as a silicon oxide film on a Si substrate.
l), gold (Au) or the like. In addition, wirings 310, 320, 331, 332 that intersect these wirings in a three-dimensional manner,
The pattern 333 can be formed in such a manner that after patterning diffusion resistance, silicide, metal, or the like of the impurity diffusion layer having a low resistance, the surface thereof is covered with an electrically insulating thin film and insulated so as to cross over. If necessary, an infrared absorption film can be formed on the infrared light receiving sensor and the compensating sensor formed of a bipolar transistor on the micro air bridge, whereby the sensitivity can be increased.

(4) Temperature Sensor of Floating Structure Next, the floating structure will be described. The floating structure is a structure that floats in the air, and has, for example, a structure like a bridge or a structure having voids / cavities above, below, or sideways. As a floating structure, for example, one that supports both ends is called an air bridge type, and one end support is called a cantilever type.
A structure in which the substrate is supported around the periphery is called a diaphragm type. The cavity may be formed on any of the back surface, the front surface, and the lateral surface. Also,
The micro air bridge in the present invention means a small air bridge.

In the following description, a schematic diagram of a transverse sectional view for explaining the floating structure is shown. Here, the description will be made mainly for the microbridge, but the present invention is not limited to this, and a floating structure such as each type described above can be adopted as the floating structure. Then, the plan view of each drawing is determined as appropriate depending on the adopted floating structure.

FIG. 7 is a sectional view of a first embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor. An npn-type bipolar transistor 10 made of a polycrystalline silicon thin film deposited on a micro air bridge 6 formed on a Si substrate 1.
Is used as a transistor thermistor.
This structure can be used as a temperature sensor such as the infrared sensor or the flow sensor shown in FIG.

An insulating film 50 and a silicon oxynitride film 51 are formed on the substrate 1. A part of the silicon oxynitride film 51 constitutes a micro air bridge 6 having a cavity 5. A bipolar transistor 10 is formed in the micro air bridge 6. The bipolar transistor 10 includes an n-type emitter region 20, a p-type base region 21, an n-type collector region 22, an emitter electrode 60, a base electrode 61, and a collector electrode 62. Note that the insulating film 501 may or may not be formed. Moreover, in each figure, the same reference numerals indicate the same components.

The cavity 5 is an example formed by anisotropic etching from the back surface of the Si substrate 1, and of course, it can be formed so that the micro air bridge 6 is left from the front surface of the Si substrate 1. As the insulating film 53 formed on the Si substrate 1, in addition to the silicon oxide film 50, it is preferable to form the silicon oxynitride film 51 having a matched thermal expansion coefficient so that the micro air bridge 6 is not distorted. The collector electrode 62, the base electrode 61, and the emitter electrode 60 of the polycrystalline silicon thin film bipolar transistor 10 are insulated from each other, so that an insulating film 52 such as PSG is formed.

When used as an infrared sensor, an infrared absorption film may be formed on the bipolar transistor 10 on the micro air bridge 6. By forming the bipolar transistor 10 of the transistor thermistor on the micro air bridge 6 in this manner, a temperature sensor such as an infrared sensor having a high speed response and high sensitivity can be manufactured.

FIG. 8 is a sectional view of a second embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor. FIG. 8 is a cross-sectional view of the micro air bridge 6 having a bipolar transistor 10 in which the direction of the cross section of the micro air bridge 6 shown in FIG. 7 is changed and the support of the micro air bridge 6 can be seen. In this figure, unlike the example shown in FIG. 7, the main body of the micro air bridge 6 is, for example, high-density boron-added Si resistant to anisotropic etching, and the high-density boron-added Si is p-type Si. Therefore, this is an example in which this is used as the emitter region 20 or the collector region 22 of the bipolar transistor 10. here,
The emitter region 20 and the base region 21 of the bipolar transistor 10 as the transistor thermistor were formed by depositing a polycrystalline silicon thin film. These production steps can be produced by a known semiconductor process.

The high-density boron-doped Si used as the collector region 22 of the bipolar transistor 10 of the micro air bridge 6 has a low resistance and can also function as a micro heater. In addition, a thin film heater material as a heating element may be further formed on the micro air bridge 6 to be used as a micro heater, and the temperature can be controlled in combination with a transistor thermistor also formed there. Since the micro air bridge 6 is used, the power consumption of the micro heater can be made extremely small, and a high-speed response temperature control system can be achieved.

FIG. 9 is a sectional view of a third embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor. This figure shows the bipolar transistor 10 on the micro air bridge 6 as shown in FIG. 8. Here, when a part of the Si substrate 1 is left in the micro air bridge 6 and the bipolar transistor 10 is formed there. FIG.

The bipolar transistor 10 uses the (111) plane of the Si substrate 1 and combines it with the anisotropic etching technique so that a part of the Si substrate 1 is placed on the micro air bridge 6 (actually, it is adhered to the lower portion thereof). It may be formed so as to be left as it is, or may be formed using an SOI (Silicon on Insulator) substrate or the like. Further, here, the main component of the micro air bridge 6 is the silicon oxide film 50. When used as an infrared sensor, an infrared absorption film 500 such as gold black or nichrome can be arranged via the insulating film 52 as shown in the figure.

FIG. 10 is a sectional view of a fourth embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor. This figure shows Si
A cavity 5 is formed on the substrate 1, and a Zener diode 30 and diffusion resistance layers 41a, 41 such as a load resistor and a resistor for bias sharing are formed on the Si substrate 1 below the cavity 5.
An example is shown in which b and 41c are formed by insulating isolation from the Si substrate 1 by a pn junction.

The resistor Ra includes an n-type diffusion resistance layer 41a and a p-type layer 42a. The resistor Rb includes an n-type diffusion resistance layer 41b and a p-type layer 42b. The resistance Rc is n
A diffusion resistance layer 41c of a mold layer and a p-type layer 42c are provided. The bipolar transistor 10 has an n-type emitter region 20,
The p-type base region 21, the n-type collector region 22, the emitter electrode 60, the base electrode 61, and the collector electrode 62 are provided. The Zener diode 30 has an n-type layer 31, p
The mold layer 32 and the electrodes 63 and 64 are provided. Emitter electrode 6
0 is connected to the diffusion resistance layer 41c, and the base electrode 61
Are connected to the diffusion resistance layer 41a. Further, the n-type collector region 22 is connected to the diffusion resistance layer 41b. In addition,
The oxide film 501 may be formed or may not be formed. In this example, as in FIG. 8, the main constituent of the micro air bridge 6 is high-density boron-doped Si, the collector region 22 of the bipolar transistor 10 is further formed thereon, and a polycrystalline silicon thin film is formed thereon to form a base region. 21 and the emitter region 20 are formed.

The bipolar transistor 10 as the transistor thermistor can also be used as a thermal infrared sensor, and a micro heater or a Peltier element can be further formed on the micro air bridge 6,
The temperature can be controlled by heating or cooling. Thus, by forming an Si integrated circuit on the Si substrate 1, forming the bipolar transistor 10 through the cavity 5 for thermal isolation formed above the Si integrated circuit, and using this as a transistor thermistor, Since the desired B constant can be selected, it is possible to provide a temperature control system or a temperature detection system that has a high-speed response with respect to heat, low power consumption, and high sensitivity.

FIG. 11 is a sectional view of the fourth embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor. In this figure, a thin film semiconductor is formed on an insulating film 53 of a micro air bridge 6, and a bipolar transistor 10 having a structure in which an emitter region 20, a base region 21 and a collector region 22 are sequentially formed in the lateral direction is a thermal infrared sensor. An example of using it as FIG. 11A is a plan view of such a thermal infrared sensor, and FIG. 11B is a cross-sectional view of the thermal infrared sensor taken along line XX of FIG. 11A.

Transistor thermistor 10 having this structure
Can be created, for example, as follows. First, an insulating film 51 made of an oxynitride film or a silicon oxide film is formed on the Si substrate 1 by CVD, for example, 10
It is formed to have a thickness of about nm. Further, an n-type polycrystalline silicon thin film is formed thereon by CVD or the like, and p
The base region 21 is formed by a thermal diffusion or ion implantation technique for forming impurities. Further, the emitter region 20 is formed to such an extent as to reach the bottom of the n-type polycrystalline silicon thin film by utilizing this diffusion or ion implantation window. Moreover, if the original n-type polycrystalline silicon thin film is used as the collector region 22, the emitter region 20, the base region 21, and the collector region 22 are formed so as to be sequentially arranged in the lateral direction (in the figure, left and right sides are shown). The emitter region 20, the base region 21, and the collector region 22 are formed symmetrically.). Therefore, in such a configuration, carriers (electrons) injected from the emitter region 20 into the base region 21 flow laterally and reach the collector region 22.

The carriers (electrons) injected from the emitter region 20 into the base region 21 as described above are
Since it is injected from the periphery of 0 into the base region 21, a large amount of carriers can be made to flow, that is, the collector resistance can be reduced by increasing the peripheral length of the emitter region 20. Based on this idea, the periphery of the emitter region 20 is made to meander. After forming the electrodes by the conventional technique, a window is opened in the insulating film 53,
Through this window, the Si substrate 1 is formed with a cavity 5 by an anisotropic etching technique from the surface, and a micro air bridge 6 is formed.
To create. Further, an infrared absorption film is formed if necessary. When the micro air bridge 6 is formed from the front surface to form the micro air bridge 6, a smaller micro air bridge 6 is formed as compared with the formation of the micro air bridge 6 from the back surface of the Si substrate 1 by the anisotropic etching technique. Since the bridge 6 can be formed and the heat capacity is reduced accordingly, an infrared sensor with high sensitivity and high speed response can be obtained, and there is an advantage that an infrared image sensor can be easily manufactured by forming an array of these.

In the above-described embodiments, the bipolar transistor 10 is often the npn type, but the same applies to the pnp type.

(5) Infrared Image Sensor FIG. 12 is a circuit diagram of a thermal infrared image sensor to which a transistor thermistor is applied. This figure is an example of a case where the thermal thermal infrared sensor array is applied to a thermal infrared image sensor. Each bipolar transistor 11, 12; 21, 2 formed in each micro air bridge 6.
2 are arranged in a matrix on the XY plane (horizontal-vertical plane). The emitter-base voltages Ve11, Ve12; Ve21, Ve22 of these respective bipolar transistors 11, 12; 21, 22 are adjusted by variable resistors Rb11, Rb12; I tried to be the same. Known horizontal scanning circuit 210, vertical scanning circuit 110, and MOSFETs 211, 212;
1, 112; 121, 122 are used to sequentially drive the respective bipolar transistors 11, 12; 21, 22 so that these bipolar transistors 11, 1;
Outputs V ₀ of the differential amplifier 300 corresponding to respective temperatures when 2; 21 and 22 are regarded as transistor thermistors are sequentially taken out. The output V at this time
₀ is the voltage drop of the load resistance RL and the voltage Vz of the stabilized power supply.
It is obtained as the difference with. The output V ₀ can be displayed on a screen of a cathode ray tube, liquid crystal, PDP or the like by a known display circuit.

As described above, in the present invention, since many thermal thermal infrared sensors can be adjusted to the same B constant, they are stable against temperature changes in the external environment, and the output display of the thermal infrared image sensor is stable. The unevenness of the brightness on the screen can be made extremely small.

(6) MOS-Type Transistor Thermistor FIG. 13 is a sectional view of a first embodiment of a micro air bridge having a MOS transistor as a transistor thermistor. In this figure, a MOS transistor 600 is formed on an n-type Si substrate 1, and this MOS transistor is operated in the subthreshold region to perform npn.
FIG. 3 is a schematic view of a cross-sectional view when treated as a bipolar transistor of a type. Although a MOS transistor is described in this example, the present invention can be applied to other field effect transistors.

The MOS transistor 600 has a channel forming region 601, an n-type source region 620, a channel region 621, and an n-type collector region 622. further,
The MOS transistor 600 includes a source electrode 660, a drain electrode 662, and a gate electrode 661 with the oxide film 50 interposed therebetween.
Equipped with. Note that the oxide film 501 may be formed or may not be formed.

Here, a channel forming region 601 forming a channel region 621 is formed on the n-type Si substrate 1, and a source region 620 and a drain region 622 are further formed in the channel forming region 601. The gate has a negative gate voltage Vg with respect to the source region 620.
Is applied to treat the depletion type n-channel as a p-type base. By operating such a MOS transistor in the subthreshold region, np
It can be handled as an n-type bipolar transistor,
Use a transistor thermistor.

Actually, even if the depletion type n-channel region does not have to be a p-type base, an n-type base region of an n-channel region having a little n-type can be used.
There is a potential barrier between the n-type base region and the high-concentration n-type emitter region (source region) when treated as the bipolar transistor, so that the B constant is small but it can be treated as a transistor thermistor. When the channel formation region 601 is a p-type, it often becomes a depletion type MOS transistor. In order to operate in the subthreshold region, for example, the electrode 660 of the source region 620 is set to the ground potential, a positive voltage (for example, 3V) is applied to the electrode 662 of the drain region 622, and the negative potential is applied to the gate electrode 661. Voltage (eg -5
V) may be applied to change the channel region 621 from an n channel to a weak p type or a weak n channel.

Although FIG. 13 shows an example of a depletion type MOS transistor, it is of course an enhancement type and can be operated as a transistor thermistor by operating in the subthreshold region. Also, when treating the source, substrate or channel formation region, and drain MOS transistor as a bipolar transistor,
It may be npn type or pnp type.

FIG. 14 is a sectional view of a second embodiment of a micro air bridge having a MOS transistor as a transistor thermistor. This figure shows a structure in which a MOS transistor 600 is formed on the SOI on the Si substrate 1, and the silicon oxide film 50 of the SOI and the MOS transistor portion thereabove are removed by etching to remove the rest, that is, the micro air bridge structure. It is a schematic diagram of a side view.

The MOS transistor 600 includes a channel formation region 601, an n-type source region 620, a channel region 621, and an n-type collector region 622 so as to be sequentially arranged in the lateral direction. Furthermore, the MOS transistor 6
00 includes a source electrode 660, a drain electrode 662, and a gate electrode 661 with the oxide film 54 interposed therebetween.

In this case, since a transistor thermistor having a thin film structure and having electric conductivity in the lateral direction can be easily formed, heat conduction to the substrate is small and heat capacity can be made small, which is suitable for application to an infrared sensor, an infrared image sensor or the like. Is. In the present embodiment, the pnp type is used, but the npn type is also applicable as long as it operates in the subthreshold region.

The present invention can be applied to field-effect transistors of both n-type and p-type channels. Further, the present invention can be appropriately applied such that the source and the drain of the field effect transistor are used in reverse and the source is used as the drain.
Further, when a MOS transistor is used as a transistor thermistor, it becomes a problem that the resistance of a long channel becomes dominant, and the channel conductance is dominated by the amount of thermal carriers in the channel due to the barrier height between the source region and the channel region. Therefore, it is better to design the channel length so as to be shorter.

Also, a static induction type transistor (SIT)
However, it can be used as a transistor thermistor. The static induction type transistor (SIT) is equivalent to a transistor in which the gate length of a junction type or MOS type field effect transistor is extremely shortened, and particularly when the gate length of a junction type field effect transistor is extremely shortened. , The gate is equivalent to an extremely short base width of the bipolar transistor.

The B constant may be adjusted by a bias circuit after the above-mentioned pure bipolar transistor 10 or a MOS transistor used as a bipolar transistor is manufactured. At the time of manufacture, a desired B constant may be manufactured. A transistor thermistor can also be created by integrating an additional bias circuit. Further, since this transistor thermistor functions as a temperature sensor, a temperature control system and a temperature detection system can be configured by combining this with a micro heater, a Peltier element, or the like.

The above-described embodiment is merely one embodiment of the present invention, and it is apparent that there are many variations of the present invention, although the spirit, action, and effect of the present invention are the same.
In the present invention, for example, material, size such as thickness and width,
The voltage, the resistance value, etc. can be appropriately selected.

[0079]

As described above, in the conventional thermistor, once the thermistor was manufactured, it was extremely difficult to control the B constant, but in the transistor thermistor of the present invention and this applied device, the emitter of a bipolar transistor is used. -The B constant can be largely changed by adjusting the base voltage or the gate voltage of the MOS transistor, so that the desired B constant can be finely adjusted and the B constants of a plurality of transistor thermistors can be set to the same value. You can

Further, since the transistor thermistor of the present invention is essentially a bipolar transistor, its amplifying mechanism can be utilized, and high sensitivity such as a thermal infrared sensor, a thermal infrared image sensor, a flow sensor, a gas sensor, a Pirani vacuum gauge, etc. It can be applied as a temperature sensor.

[Brief description of drawings]

FIG. 1 is a basic circuit diagram of a transistor thermistor of the present invention.

FIG. 2 is another basic circuit diagram of the transistor thermistor of the present invention.

FIG. 3 is a cross-sectional view of a transistor thermistor having a bipolar transistor formed on a substrate.

FIG. 4 is a cross-sectional view of a transistor thermistor in which a plurality of npn-type bipolar transistors are formed on the same substrate.

FIG. 5 is a circuit diagram including a plurality of transistor thermistors.

FIG. 6 is an explanatory diagram of a case where a plurality of transistor thermistors are applied to a thermal infrared sensor and integrated on a semiconductor substrate.

FIG. 7 is a sectional view of a first embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor.

FIG. 8 is a sectional view of a second embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor.

FIG. 9 is a cross-sectional view of a third embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor.

FIG. 10 is a cross-sectional view of a fourth embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor.

FIG. 11 is a sectional view of a fifth embodiment of a micro air bridge having a bipolar transistor as a transistor thermistor.

FIG. 12 is a circuit diagram of a thermal infrared image sensor to which a transistor thermistor is applied.

FIG. 13 is a cross-sectional view of a first embodiment of a micro air bridge having a MOS transistor as a transistor thermistor.

FIG. 14 is a cross-sectional view of a second embodiment of a micro air bridge having a MOS transistor as a transistor thermistor.

[Explanation of symbols]

1 Substrate 5 Cavity 6 Micro Air Bridge 10, 10a, 10b, 10c; 11, 12, 21, 2
2 bipolar transistor 20 emitter region 21 base region 22 collector region 30 Zener diode 41 diffusion resistance layer 50 silicon oxide thin film 51 silicon oxynitride film 52 insulating film 53 insulating film 60 emitter electrode 61 base electrode 62 collector electrode 100 stabilizing power supply 620 source Region 621 Channel region 622 Drain region

Claims (16)

(57) [Claims] 1. A bias circuit for outputting a first voltage, and an output of the bias circuit is applied as a forward bias voltage between an emitter and a base, a second voltage is applied to a collector, and a collector current is output. And a temperature dependence of the collector current with respect to the collector voltage of the transistor, the transistor is used so as to correspond to the temperature dependence of the current when the collector resistance of the transistor is regarded as a thermistor, The forward bias voltage is adjusted by adjusting the output voltage value of the bias circuit, and the potential barrier height between the emitter and the base of the transistor is adjusted by the forward bias voltage. The thermistor constant, which represents the temperature dependence, can be adjusted to a desired value. Measuring device. 2. The transistor is formed such that each semiconductor region is sequentially arranged in a lateral direction in a thin film semiconductor layer, and most carriers injected from an emitter region flow laterally to reach a collector region. The temperature measuring device according to claim 1. 3. The bias circuit according to claim 1, further comprising a voltage dividing resistor set in advance so as to have an emitter-base voltage for realizing a predetermined thermistor constant. The temperature measuring device described. 4. The temperature measuring device according to claim 1, further comprising a constant voltage power source circuit integrated on the same substrate as the transistor and used as a power source for adjusting the transistor. 5. A plurality of the transistors are formed on the same substrate, and the thermistor constants of the transistors are made the same or substantially the same by adjusting the bias circuits. The temperature measuring device according to any one of 4 above. 6. The transistor according to claim 1, wherein the transistor is formed in or on a thin film, and the thin film is coupled to a substrate by a floating structure and has a cavity in an upper portion, a lower portion or a lateral portion. The temperature measuring device according to any one of 5 above. 7. A bias for outputting a first voltage, which has a preset voltage dividing resistor so that a gate voltage for realizing a negative temperature coefficient thermistor constant or a channel state of a channel forming region is set. A circuit and a field effect transistor in which an output of the bias circuit is applied as a bias voltage between the source and the gate, a second voltage is applied to the drain, and a drain current is output. The sub-threshold region of the voltage-current characteristic is operated so as to correspond to a bipolar transistor, and the temperature dependence of the drain current with respect to the gate voltage of the field effect transistor is
The field effect transistor is used as a thermistor having a negative temperature coefficient so as to correspond to the temperature dependence of the current when the drain resistance of the field effect transistor is regarded as a thermistor, and the output voltage value of the bias circuit is adjusted. By adjusting the bias voltage or the channel state of the channel forming region and adjusting the potential barrier height between the source and drain of the field effect transistor by the bias voltage, the temperature dependence of the drain resistance of the field effect transistor A temperature measuring device capable of adjusting the thermistor constant representing the value to a desired value. 8. The field effect transistor is formed such that each semiconductor region is sequentially arranged in a lateral direction in a thin film semiconductor layer, and most carriers injected from a source region flow in the lateral direction to reach a drain region. The temperature measuring device according to claim 7, wherein 9. The temperature measuring device according to claim 7, further comprising a constant voltage power supply circuit integrated on the same substrate as the field effect transistor and used as a power supply for adjusting the field effect transistor. 10. A plurality of the field effect transistors are formed on the same substrate, and the thermistor constants of the field effect transistors are made the same or substantially the same by adjusting the bias circuits. The temperature measuring device according to any one of 7 to 9. 11. The field effect transistor is formed in or on a thin film, the thin film being coupled to a substrate by a floating structure, and having a cavity in an upper portion, a lower portion or a lateral portion. The temperature measuring device according to any one of 7 to 10. 12. A thermal infrared image sensor in which a plurality of temperature measuring devices according to any one of claims 1 to 11 are formed in a matrix and the output of each of the temperature measuring devices is read out. 13. A first voltage is output from a bias circuit, the output of the bias circuit is applied as a forward bias voltage of a transistor between an emitter and a base, a second voltage is applied to a collector, and a collector current is applied. Is used as the output, and the temperature dependence of the collector current with respect to the collector voltage of the transistor is such that the temperature dependence of the current when the collector resistance of the transistor is regarded as a thermistor is used, and the output of the bias circuit The forward bias voltage is adjusted by adjusting the voltage value, and the height of the potential barrier between the emitter and the base of the transistor is adjusted by the forward bias voltage to represent the temperature dependence of the collector resistance of the transistor. A temperature measuring method capable of adjusting the thermistor constant to a desired value. 14. The temperature measuring method according to claim 13, wherein the emitter and the collector of the transistor are used in reverse, and the emitter is used as the collector. 15. A first voltage is output from a bias circuit having a preset voltage dividing resistor so that a gate voltage for realizing a thermistor constant having a negative temperature coefficient or a channel state of a channel forming region is set. The output of the bias circuit is applied between the source and the gate as the bias voltage of the field effect transistor, the second voltage is applied to the drain, and the drain current is output. The sub-threshold region is operated so as to correspond to a bipolar transistor, and the temperature dependence of the drain current with respect to the gate voltage of the field effect transistor is
By using the field effect transistor as a thermistor having a negative temperature coefficient so as to correspond to the temperature dependence of the current when the drain resistance of the field effect transistor is regarded as a thermistor, by adjusting the output voltage value of the bias circuit, By adjusting the bias voltage or the channel state of the channel formation region and adjusting the potential barrier height between the source and drain of the field effect transistor by the bias voltage, the temperature dependence of the drain resistance of the field effect transistor is represented. A temperature measuring method capable of adjusting the thermistor constant to a desired value. 16. The temperature measuring method according to claim 15, wherein the source and the drain of the field effect transistor are used in reverse, and the source is used as the drain.