JPS6247526A - Pyroelectric type temperature detecting device - Google Patents

Abstract

PURPOSE:To constitute the titled device so that all amplifier circuits are formed by a semiconductor technique, and an external circuit is not required, by forming as one body a pyroelectric sensor and at least the amplifier circuit for amplifying a detecting signal from the pyroelectric sensor. CONSTITUTION:The titled device is provided with a silicon base material 1, an amplifier circuit 11 and peripheral circuits 12-15 which have been formed on a peripheral circuit forming part 10 of the base material 1, a recessed part corner part 22, an electrode member 21 consisting of the respective electrodes 21a-21d which have been formed on the surface of each corner part 21a-21d of the corner part 22, and a pyroelectric sensor 3, and the sensor 3 contacts to the surface of the electrodes 21a-21d. As for the circuit 11 for amplifying a pulsative charge signal from this sensor 3 to a prescribed level, a high resistance input resistance component is formed by an impurity non-diffuse polycrystal silicon, and a low resistance output resistance component is formed by an impurity diffusion polycrystal silicon. In this state, among the circuits 12-15, an output of the low-pass filter 15 is A/D-converted, and expressed in terms of a final temperature through a prescribed arithmetic circuit.

Description

[Detailed Description of the Invention] Summary of the Invention A pyroelectric temperature detection device that integrates a pyroelectric sensor and an amplifier circuit that amplifies at least a detection signal from the pyroelectric sensor, in particular, a high-resistance input in the amplifier circuit. The resistance portion is formed of impurity-diffused polycrystalline silicon, and the low-resistance output resistance portion is formed of impurity-diffused polycrystalline silicon or a junction resistance of a MOS FET.

Field of the Invention The present invention relates to a pyroelectric temperature detection device, and more specifically, to a pyroelectric temperature detection device in which a pyroelectric sensor and its peripheral signal processing circuit are integrally formed on a semiconductor substrate. This invention relates to a detection device.

C. Prior art and problems to be solved by the invention Piezoelectric and ferroelectric materials exhibit the pyroelectric effect, a phenomenon in which charges are induced on their surfaces due to polarization when exposed to radiation. It is known. Therefore, the charge induced on the surface of an object having a pyroelectric effect, that is, a pyroelectric body, is measured, and the incident radiation dose is proportional to the surface temperature of the object to be measured. It is possible to calculate the amount of heat of an incident radiation source, and is used as a pyroelectric temperature detection device, that is, as a non-contact temperature sensor, in various devices such as microwave ovens, fire detection devices, etc.

As a pyroelectric substance, lithium tantalate (LiTaOz
), piezoelectric ceramics such as PZT, and piezoelectric polymer films such as polyvinylidene fluoride (PVF2) are known, and they have a large pyroelectric coefficient as pyroelectric materials used in pyroelectric temperature detection devices. Preferably.

As described above, charges are induced on the surface of a dielectric that has been exposed to radiation, but when the same level of radiation is received, the induced charges are neutralized over time. That is, induced charges are generated in response to temperature changes. For this reason, when used as a pyroelectric temperature detection device, the radiation incident on the pyroelectric body is chopped at a predetermined cycle, and the radiation incident on the pyroelectric body is intentionally interrupted to detect temperature changes. The induced charge is extracted as a pulse having an amplitude depending on the temperature of the incident radiation.

In this way, the induced charge is a pulse, and the output impedance of the pyroelectric body is high, for example, 10
Although the impedance is approximately Ω), a signal processing circuit (conversion circuit) is provided after the pyroelectric body serving as a sensor unit and before a circuit for converting temperature.

As for the signal processing circuit, the conventional one is shown in FIG. 7, and the recent one is shown in FIG. There is a "processing circuit").

In the signal processing circuit shown in FIG. 7, an amplifier 102, a bandpass filter 103, a sample holder 104', and a low-pass filter 105 are connected in series to a sensor part 101 as shown. Radiation from a radiation source 110 , more specifically infrared radiation, is applied to the sensor part 101 intermittently by a chopper 106 . Further, the sample holder 104' holds the pulse signal from the sensor part 101 in synchronization with the signal from the photo ink clubter 107.

The signal processing circuit shown in FIG. 8 has the disadvantage that the signal processing circuit shown in FIG. This was devised to solve the problem of not being able to obtain accurate measurements. The sensor signal processing circuit shown in FIG. 8 includes an amplifier circuit 102 that amplifies the pulse signal from the sensor part 101, a bandpass filter 103 that removes noise components from the amplified signal, a sample holder 104, and a low-pass filter. 105 and a hold pulse generation circuit 108.

The operation of the circuit shown in FIG. 8 will be described with reference to FIGS. 9 fa) and ('b). FIG. 9(a) shows a phenomenon that occurs in the sensor part 101, the amplifier circuit 102 and the bandpass filter 103.
The waveform of the pulse signal that passes through the sample holder 104 and is applied to the hold pulse generation circuit 108 is shown.

FIG. 9(b) shows the holding signal S4 of the sample holder 104.

First, upon receiving the pulse signal S3□, the Hall pulse generation circuit 108 detects its amplitude and outputs a sample hold pulse S8 to the sample holder 104. Upon receiving the sample hold pulse S8, the sample holder 104 first quickly clears the previous held value. For example, the held value is quickly cleared by forcibly discharging the charge in a capacitor (not shown) in the sample holder 104.

Next, the applied pulse signal S31 is held.

Hereinafter, the same process is performed for the signals S3□ and S33.

Next, regarding the case where the radiation level decreases, as described above, since the previous value is quickly cleared, the values corresponding to the peak values of the signals 33a and S3s are held. Therefore, it is not affected by the previous value as in the past, so even if the radiation level decreases,
Accurate peak values can be maintained.

Incidentally, the pyroelectric sensor section using a conventional pyroelectric material and the peripheral signal processing circuit (conversion circuit) are generally separated.

That is, the pyroelectric sensor section is mounted on an acrylic base or the like, and the above-mentioned preprocessing is performed in a peripheral signal processing circuit remote from the detection section via a conductive wire.

However, the electric charge detected by the pyroelectric sensor section is generally low and there are problems such as signal attenuation if the conductive path to the peripheral signal processing circuit is long and the sensor is easily affected by noise. Therefore, considerable attention must be paid to instrumentation. Furthermore, when separated, the overall space is generally increased, and there is a problem in that the installation conditions for devices subject to limited accommodation space, such as microwave ovens, become stricter.

At least from the standpoint of noise resistance, it is desirable that the pyroelectric sensor and amplifier be integrated in close proximity.

FIG. 10 shows a circuit example of a pyroelectric sensor and an amplifier circuit.

That is, the pyroelectric sensor 101 and the input resistor 12
2. An amplifier 102 is shown in which an FE7123 as an amplification transistor and an output resistor 124 are connected as shown. A power supply Vcc is connected to the FET 123, and the induced charge of the pyroelectric sensor 101 is transferred to the FET 123.
The amplified output signal is applied to the gate of ■. , taken from T. Here, the resistance value of the input resistor 122 is about 1010Ω, and the resistance value of the output resistor 124 is about 10Ω.

The amplifier circuit 102 is composed of individual parts, has a relatively large number of parts, and cannot be miniaturized as is. Further, according to the conventional method, the resistor is attached externally to the semiconductor substrate, and there is a problem that it is impossible to achieve miniaturization, simplify wiring, and completely integrate the peripheral circuit and the pyroelectric sensor.

Means for Solving Problem 29 and Effects In order to solve the above problems, the present invention provides a semiconductor base material, and an outer peripheral corner of a recess formed in a pyroelectric sensor mounting portion of the semiconductor base material. a pyroelectric sensor fixed to a provided electrode member; and a pyroelectric sensor formed on a peripheral circuit forming portion of the semiconductor base material.
an amplifier circuit having a high-resistance input resistance component, an amplification transistor, and a low-resistance output resistance component, wherein the high-resistance human resistance component is formed of impurity-undiffused polycrystalline silicon, and the low-resistance output resistance component is formed of impurity-diffused polycrystalline silicon. A pyroelectric temperature sensing device is provided, characterized in that it is made of polycrystalline silicon.

Further, in the present invention, the high-resistance input resistance component is formed of impurity-doped polycrystalline silicon, and the low-resistance output resistance component is formed of a junction resistance of a MOS-FET.
A pyroelectric temperature detection device is provided.

E. Embodiments Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a perspective view of a pyroelectric temperature detection device as an embodiment of the present invention when assembled.

The pyroelectric temperature detection device includes a silicon base material 1, peripheral circuits 11 to 15 formed in a peripheral circuit forming portion 10 of the base material,
Recessed corner 2 formed in the pyroelectric sensor mounting portion 20 of the base material
2. A recess defined by the bottom of the recess, and a corner of the recess 2
The electrode member 21 includes electrodes 21a to 21d formed on the surfaces of the corner portions 21a to 21d of 2, respectively. The pyroelectric temperature detection device also includes a pyroelectric sensor 3, which is fixed to the electrodes 21a to 21d to form an integrated pyroelectric temperature detection device.

The peripheral circuits 11 to 15 include, for example, an amplifier 1 that amplifies the pulsed charge signal from the pyroelectric sensor 3 to a predetermined level.
1. A band-pass filter 12 that passes a signal of a specific frequency component among the output signals of the amplifier; a hold pulse generation circuit 13 that detects the peak value of the output pulses of the band-pass filter and generates a sample-and-hold signal;
A sample holder 1 that holds the peak value of the output pulse of the bandpass filter 12 in response to the sample hold signal.
4, and a low-pass filter 15 that passes low frequency components of the output signal of the sample holder. The output signal of the low-pass filter 15 is A/D converted and converted into a final temperature via a predetermined arithmetic circuit. Of course, it is also possible to form the A/D converter and arithmetic circuit used in these on the silicon base material 1.

FIG. 2(a) is a plan view of the pyroelectric sensor mounting portion 20 and electrodes 21a to 21d in FIG. 1, and FIG. show.

The pyroelectric sensor mounting portion 20 has a rectangular recess formed therein, and has recess corner portions 222 to 22c whose four corners protrude inward. These concave portion partitions 222
~22c is surrounded by < (111) planes as shown in the figure, and is formed by etching as described later.

As shown in the figure, the recessed portions are provided for the pyroelectric sensor 4 and the electrode 2.
This is to further reduce the contact area with the substrate 1 via 1a to 21d. In other words, as mentioned above, the pyroelectric sensor receives a change in radiation and generates an electric charge according to the change, but if the contact area with the base material 1 is large, the energy of the incident radiation is transmitted to the base material 1. Since the amount of contact is large and the error becomes large, it is necessary to make the contact area smaller.

Therefore, the area that contacts the base material 1 via the electrode is made as small as possible, and for this reason, the non-contact area of the pyroelectric sensor mounting section, that is, the lower part where the pyroelectric sensor is mounted, is hollowed out. In addition, by providing the concave portion as described above, the concave portion becomes a cavity and reduces the heat dissipation of the pyroelectric sensor, while minimizing heat conduction to the base material, so that the radiation received by the pyroelectric sensor is Errors caused by dissipation become smaller.

Next, the formation of the amplifier circuit will be described in detail.

3 and 4 show a circuit diagram and a plan view of the amplifier circuit 11 of FIG. 1 and its related parts.

The amplifier circuit 11 shown in FIG. 3 is equivalent to the circuit shown in FIG. 10, but whereas the circuit in FIG. The circuit shown in the figure is formed using semiconductor manufacturing technology.

In FIGS. 3 and 4, the amplifier circuit 11 includes a high-resistance input resistor 111, an n-channel FET 122 as an amplification transistor, and a low-resistance output resistor 113. FET 122 is formed on semiconductor substrate 1 by a normal MOS FET manufacturing process. The resistance value of the high-resistance input resistor 111 is 10''Ω, and it is formed by depositing polycrystalline silicon on silicon oxide on the silicon substrate 1 by vapor phase reaction without diffusing impurities. The low-resistance output resistor 113 has a resistance value of h' 10 KΩ, and is formed of polycrystalline silicon by diffusing impurities such as phosphorus (P) onto silicon oxide on a silicon base material l. ing.

The right sheath in FIG. 4 shows a bonding pane, and other peripheral circuits in FIG. 1 are not shown.

As described above, by forming the resistors 111, 113 and FET, without using external resistors etc.
An integrated pyroelectric temperature sensing device is formed.

5 and 6 show a second embodiment of the amplifier circuit.

The amplifier circuit 11a shown in FIGS. 5 and 6 is constructed by implementing a low-resistance output circuit using the junction resistance of the MOS piT 114 in contrast to the amplifier circuit 11 shown in FIGS. 3 and 4. The MO5FET '114 is an amplification FET
It can be formed using the same process as 112. The formation of high resistance input resistor 111 is similar to that described above.

The amplifier circuit 11a shown in FIGS. 5 and 6 has a somewhat simpler manufacturing process and a smaller space than the amplifier circuit 11 shown in FIGS. 3 and 4. There are advantages.

Effects of the Invention As described above, according to the present invention, at least the pyroelectric sensor and the amplifier circuit are integrated into a compact semiconductor chip, and the amplifier circuit is entirely formed using semiconductor technology and does not require external circuitry. The effect is that it is not necessary.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an integrated pyroelectric temperature detection device as an embodiment of the present invention, FIG. 3 and 4 are a circuit diagram and a plan view of a first embodiment of the amplifier circuit in FIG. 1, and FIGS. 5 and 6 are a circuit diagram and a plan view of a second embodiment of the amplifier circuit in FIG. , FIG. 7 is a conventional sensor signal processing circuit diagram, FIG. 8 is a sensor signal processing circuit diagram suitable for implementing the present invention, and FIGS. 9(a) and 9(b) are signals explaining the operation of the circuit in FIG. The waveform diagram and FIG. 10 are circuit diagrams of the sensor and amplifier circuit of FIG. 8. (Explanation of symbols) 1... Base material, 10... Peripheral circuit forming part, 11, 113... Amplifier Circuit, 12-15... Peripheral circuit, 20... Pyroelectric sensor mounting part, 21... Electrode forming part, 22... Corner of recess, 23... Bottom of recess, 3... Focus Electrical sensor, 111... High resistance input resistor, 11th... Amplifying FET, 113, 114... Low resistance output resistor. A perspective view of a pyroelectric temperature detection device as an embodiment of the present invention. 1
: Base material 10: Peripheral circuit forming parts 11 to 151 Peripheral circuit 20: Pyroelectric sensor mounting part 21: Electrode forming part 22: Concave corner part 23 Concave bottom part 3 Pyroelectric sensor (a) (b) Base material concave shape Fig. 2 Amplifier circuit diagram of the first embodiment of the present invention Fig. 3 A top view of Fig. 3 Fig. 4 Amplifier circuit diagram of the second embodiment of the invention Fig. 5 Fig. 6 Conventional sensor signal processing circuit FIG. 7: A sensor signal processing circuit suitable for the present invention FIG. 8: IME FIG. 8: A signal waveform diagram illustrating the entire operation of the circuit FIG. 9: r'. 2 Circuit diagram of the sensor and amplifier circuit in Figure 8 Figure 10

Claims (1)

[Scope of Claims] 1. A semiconductor base material (1), a pyroelectric sensor mounting portion (20) of the semiconductor base material having a focus surface attached to an electrode member provided at an outer peripheral corner of a concave portion formed in a pyroelectric sensor mounting portion (20). an electric sensor (3), and a high-resistance input resistance component (111), an amplification transistor (112), and a low-resistance output resistance component (113, 114) formed in the peripheral circuit forming portion (10) of the semiconductor base material.
), the high-resistance input resistance component is formed of impurity-diffused polycrystalline silicon, and the low-resistance output resistance component is formed of impurity-diffused polycrystalline silicon. Pyroelectric temperature detection device. 2. A semiconductor base material (1), a pyroelectric sensor (3) surface-attached to an electrode member provided at an outer peripheral corner of a concave portion formed in a pyroelectric sensor mounting portion (20) of the semiconductor base material; and a high-resistance input resistance component (111), an amplification transistor (112), and a low-resistance output resistance component (113, 114) formed in the peripheral circuit forming portion (10) of the semiconductor base material.
), wherein the high-resistance input resistance component is formed of impurity-doped polycrystalline silicon, and the low-resistance output resistance component is formed of a junction resistance of a MOS-FET. Features of pyroelectric temperature detection device.