JPS5967433A - Temperature/pressure detector - Google Patents

Abstract

PURPOSE:To enable simultaneous detection of a pressure compensated for temperature and a temperature from an output of a silicon element by supplying an output of a piezo-electric vibrator to a temperature compensation circuit in a composite sensor unit comprising the piezo-electric vibrator and the silicon pressure sensor. CONSTITUTION:A composite sensor 2 is made up of a piezo-electric vibrator 3 and a silicon element 4 stuck together. When a fixed pressure distortion is applied to the piezo-electric vibrator 3, an alternate current of the frequency f0 the same as the vibration frequency of the piezo-electric vibrator 3 is detected from the output end of the silicon element 4. Outputs at output ends 2 and 4 of the composite sensor 2 are supplied to a temperature compensation circuit 6 through a detector 5 and a temerature compensation signal is supplied to the temperature compensation circuit 6 with the temperature detection output from the vibrator 3 as comparison reference voltage. The output of the compensation circuit 6 is amplified with an amplifier 7 and outputted into a pressure display section 8. An output voltage of the composite sensor 2 is the function of the temperature and applied to a temperature display section 12. No change appears in the output voltage of the pressure display section 8 even when the output voltage changes due to a temperature variation because the pressure is constant. Thus, the temperature compensation is accomplished as expected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature and pressure detection device suitable for application to, for example, a device that automatically controls the temperature and atmospheric pressure of a semiconductor manufacturing chamber.

In the past, separate sensors were required to detect temperature and pressure. Therefore, the reality is that temperature and pressure are displayed and detected separately based on the output from each sensor.

However, in order to detect temperature lW and pressure, dedicated sensors must be installed at the installation locations, which poses difficulties in location selection and work man-hours. Further, the respective sensors are influenced by each other and produce errors. That is, a temperature sensor is harmful to changes in pressure, and a pressure sensor is harmful to temperature.

Therefore, since the respective change values are not mutually compensated,
It is not possible to continuously and automatically detect temperature and pressure with good accuracy.

In view of this, the present invention integrates a piezoelectric vibrator that primarily detects temperature and a silicon pressure sensor that primarily detects pressure, thereby canceling out their negative effects, and inserting a temperature compensation circuit. The main purpose of this invention is to propose this heavy-duty detection device that improves the performance of both temperature and pressure detection values.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit configuration diagram showing an example of the present invention.

Reference numeral 9 indicates an oscillator, the output of which is applied to the composite sensor 2.

The composite sensor 2 has a structure in which a piezoelectric vibrator 3 and a silicon element 4 are bonded together as shown in FIG. 2.As shown in FIG. 3, a pressure introduction point 5a is provided in the center. The composite sensor 2 is mounted on the case 5. In the figure, A,
B indicates a lead wire of the piezoelectric vibrator 3, and ■■■■ indicates a lead wire of the silicon element 4.

The piezoelectric actuator 3 exhibits impedance characteristics that exhibit maximum and minimum values by changing the frequency, as shown in FIG. The minimum impedance point is fr, the maximum impedance point is fa, and the capacitance C of the piezoelectric vibrator 3 is
By connecting an inductance L that resonates with a frequency fo approximately intermediate between d, fr, and fa in parallel as shown in Figure 5, the impedance becomes maximum at an intermediate frequency of 1° as shown in Figure 6. A configuration exhibiting the characteristics can be obtained.

This impedance characteristic changes with temperature and pressure. That is, as shown in FIG. 7, as the temperature T rises, f. As shown in FIG. 8, as the pressure P increases, the impedance Z decreases.

On the other hand, the silicon element 4 is constructed by connecting electrical resistors 1 (, ~ t4) provided by a diffusion method on a silicon wafer in a bridge shape. Fig. 9 shows the configuration of the silicon element 4. In this circuit diagram, the ■■ terminals represent input terminals, and the ■■ terminals represent output terminals. By applying a predetermined voltage to the input terminals, R1 to It
. When all the resistors are balanced, no output is produced, but
When pressure strain is applied to the silicon element 4, the resistance balance of R4 to R7 is disrupted, producing an output. This output appears in proportion to the pressure, and shows a characteristic curve as shown in FIG. 10 (C).

However, as shown in FIGS. 2 and 3, the piezoelectric vibrator 3
and the silicon element 4 are bonded together, a certain pressure strain is applied to the piezoelectric vibrator 3. Alternating current is detected, and this frequency matches the intermediate frequency f0. Also, the output voltage level generated at the output terminal ■■ at this time corresponds to the impedance value Zo at the intermediate frequency fo. Therefore, piezoelectric vibration By adopting the maximum frequency of 1° for the intermediate frequency of the element 3, the vibration amplitude becomes sharper, and the output of the silicon element 4 also increases.
Intermediate pressure also increases. In FIG. 3, when there is a slight change in pressure from the pressure introduction point 5a, the piezoelectric vibrator 3
and the vibration amplitude (
Z in Figure 6.

value) will change, and therefore the vertical pressure between the output ends will also change. However, even if the pressure strain is constant, this voltage changes as the temperature changes (see FIG. 7).

Therefore, in FIG. 1, the output terminal ■■ of the composite sensor 2 is supplied to the temperature compensation circuit 6 via the detector 5 1-1, while the temperature detection output from the piezoelectric vibrator 3 is used as a comparison reference voltage to the temperature compensation circuit 1-1. 6 to supply a temperature compensation signal. The output of the temperature compensation circuit 6 is amplified by an amplifier 7 and output to a pressure display section 8. Therefore, at the output stage of the composite sensor 2, even when the pressure is constant as shown in FIG. 11, even if the output voltage changes due to a change in temperature, the output voltage at the pressure display section 8 is as shown in FIG. 12. As shown in the figure, there is no change in the output voltage even if there is a change in temperature.
This means that temperature compensation has been achieved.

Furthermore, if the composite sensor 2 is configured as described above, the bias pressure is applied by the piezoelectric vibrator 3 so that the point P in FIG. 10 is the center. By adding it appropriately, it is possible to improve the custom-made curve shown in FIG. 1 in a straight line, thereby increasing the sensitivity of pressure detection.

In FIG. 1, the composite sensor 2 is driven by an oscillator 9, and its output is converted into a DC component output through a discriminative detector 10, amplified by an amplifier 11, and output to a temperature display section 12.

Note that the oscillator 9 has a frequency f. A structure is adopted in which the output is kept constant by controlling the voltage, and the frequency is controlled so that the output is maximized. J driving of the silicon element 4 is applied by processing the output from the oscillator 9 in a rectifier circuit 13 and a stabilizing circuit 14 . FIG. 13 is a diagram showing the relationship between the direct pressure at the output end of the composite sensor 2 and the pressure.

FIG. 14 is a circuit diagram showing another example of the present invention.

In this example, as is clear with reference to FIG. 1 and FIG. The configuration is as follows. Note that the same elements as in the example of FIG. 1 will be described with the same reference numerals. Therefore, in this example, the same effect as in the example shown in FIG. 1 can be achieved.

As described above, according to the present invention, in a temperature and pressure detection device using a composite sensor that integrates a piezoelectric vibrator and a silicon element, by supplying the output of the piezoelectric vibrator to the compensation circuit, Since the configuration is configured to simultaneously detect the temperature-compensated pressure and the fan a from the output of the element, the sensitivity of the detected pressure value can be improved, and the temperature
It is possible to obtain compensated detection values.

Therefore, it is practical to employ it when detecting temperature and pressure in a semiconductor manufacturing room, for example.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of the present invention, FIG. 2 is a diagram showing an example of a composite sensor, FIG. 3 is a diagram showing a mounting state of the composite sensor, FIG. 4 is a characteristic diagram of a piezoelectric vibrator, and FIG. Figure 5 is a circuit diagram showing an example of a piezoelectric sensor incorporating a coil, and Figure 6 is the one in the 5th column! The caustic diagram, Figure 7 is a diagram showing the relationship between frequency near room temperature, which is a characteristic of the piezoelectric sensor, and temperature, Figure 8 is a diagram also showing the relationship between pressure and impedance, and Figure 9 is the configuration of the silicon element. FIG. 10 is a characteristic diagram of the example in FIG. 9, FIG. 11 is a characteristic diagram of the composite sensor, FIG. 12 is a curve diagram for explaining the external voltage of the device of the present invention, and FIG. 13 is the same output 'A curve diagram showing the relationship between voltage and pressure. FIG. 14 is a circuit diagram showing another example of the present invention. 2... Composite sensor, 3... Piezoelectric vibrator, 4... Silicon element, 6... Temperature compensation circuit. Agent: Takashi Akiyama Figure 1 Figure 7 T-Ra Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 91-

Claims (1)

[Claims] In a temperature and pressure detection device using a composite sensor that integrates a piezoelectric vibrator and a silicon pressure sensor, the output of the piezoelectric vibrator is supplied to a temperature compensation circuit to obtain temperature-compensated pressure from the output of the silicon pressure sensor. A temperature and pressure detection device characterized in that it detects both temperature and temperature at the same time.