JPH04212032A - Compound sensor and compound transmitter and plant system using it - Google Patents

Abstract

PURPOSE:To enable differential pressure measuring accuracy to be improved by eliminating characteristic compensation of influence of differential pressure and plant control performance to be improved by reducing processing time. CONSTITUTION:A pressure difference which is generated at both edges of an orifice 560 which is provided halfway at a pipe line 550 of a chemical plant, etc., is measured by a compound transmitter 300 and a flow within the pipe line is obtained and is transmitted to a control device 500. The control device 500 controls a pump which gives pressure to the fluid within the pipe line according to the measured flow and makes an adjustment so that a proper flow can be sent. Then, for eliminating a nonlinear influence when the pressure difference is operated, gauge resistors for detecting static pressure 5-8 are placed so that a stress which is generated by the differential pressure is equal and the static pressure is measured by forming a bridge for canceling the influence of the differential pressure which operates on each gauge resistor for detecting static pressure.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a composite sensor that improves the characteristics of a static pressure sensor in a differential pressure transmitter for detecting flow rate and pressure in a chemical plant, etc. under differential pressure load, and a composite transmitter using the same. Regarding plant systems.

0002

[Prior Art] Conventionally, a composite sensor used in the sensing section of an intelligent differential pressure transmitter consists of differential pressure, static pressure, and temperature sensors on one substrate, and the three types of sensors compensate each other. It is configured to measure differential pressure with high accuracy. However, with conventional composite sensors, it is known that the output of each sensor cannot independently detect the amount of change in each, and that the outputs of the sensors influence each other.

[0003] Conventional differential pressure transmitters measure the pressure difference ΔP that occurs when liquid pumped by a pressure pump passes through an orifice installed in a pipeline of a chemical plant, etc. The flow rate is detected by

0004

[Math 1]

[0005] Here, Q is a flow rate, and k is a constant determined by the Reynolds number and the like. As mentioned above, the differential pressure sensor output is affected by the static pressure Ps and temperature T, so even when measuring the flow rate, the static pressure Ps applied to the pipeline and changes in the surrounding temperature become disturbances, and these effects can be overcome. It needs to be removed as much as possible. For this reason, conventionally, in addition to differential pressure transmitters, static pressure Ps
A pressure transmitter was installed in the same pipeline to detect the

[0006]

[Problems to be Solved by the Invention] A conventional differential pressure transmitter using a composite sensor is configured to detect static pressure, temperature, and differential pressure with each sensor. Since each amount of change is detected in an added state, corrections have been made using complicated procedures to remove these mutual influences.

Furthermore, when a diaphragm for differential pressure detection and a diaphragm for static pressure detection are provided on one semiconductor substrate, there is a problem that the distance between the two diaphragms becomes narrow during the etching process, and the adhesive strength with the base decreases.

In addition, when forming a differential pressure detection diaphragm with a central rigid body part using anisotropic etching, <11
A rectangular central rigid body portion surrounded by 1> planes is most likely to be formed, and there is a problem that stress is concentrated at the corners and the withstand pressure is lowered.

Furthermore, if the diaphragm for differential pressure detection and the diaphragm for static pressure detection have the same thickness, the diaphragm for static pressure detection will become too small when downsizing the semiconductor substrate, making it difficult to arrange a gauge resistor. There's a problem.

[0010] The static pressure sensor in the conventional composite sensor is provided to correct the output of the differential pressure sensor, and has the problem that the output of the static pressure sensor alone is small and is greatly affected by the differential pressure load. there were. Therefore, there is a problem that sufficient static pressure detection accuracy cannot be obtained, and even though the sensors are combined, a differential pressure transmitter and a pressure transmitter must be installed together in the same pipeline.

An object of the present invention is to provide a composite sensor in which a static pressure sensor is constructed so as to remove the influence of differential pressure acting on the static pressure sensor when differential pressure is applied, and to provide a simple and easy-to-use sensor by using the composite sensor. It is an object of the present invention to provide a composite transmitter that can detect differential pressure and static pressure with high precision through calculation.

Another object of the present invention is to process the differential pressure diaphragm so that it is thinner than the static pressure diaphragm, or to improve the etching procedure in order to improve the detection accuracy of the composite sensor constituting the composite transmitter. The purpose of the present invention is to provide a method for manufacturing a composite sensor, which involves devising improvements to the process and limiting the impurity concentration of the silicon substrate.

Another object is to provide a sensor arrangement that maintains constant adhesive strength.

Another object is to provide a central rigid body shape with high pressure resistance.

Another object of the present invention is to provide a chemical plant system that measures flow rate using a high-precision composite transmitter.

Another object of the present invention is to provide the functions of two differential pressure transmitters and two pressure transmitters with one composite transmitter.

[0017]

[Means for Solving the Problems] In order to achieve the above object, one or more static pressure sensor diaphragms are provided separately from the differential pressure sensor diaphragm, and a gauge resistor and a fixing part are provided on the static pressure sensor diaphragm. In a static pressure sensor that detects static pressure by performing arithmetic processing using the output of a gauge resistor installed in the sensor, the gauge resistor for each static pressure sensor is The structure is such that they are placed at positions where stress due to differential pressure load is applied almost equally. Furthermore, by using the above-mentioned sensors, the structure of the correction map recorded in the processing circuit is simplified, and signal processing can be performed by simply adding and subtracting the outputs of each sensor.

Furthermore, in order to achieve other purposes, a static pressure sensor and a differential pressure sensor that have a large output and are small in the influence of differential pressure are mounted on one sensor chip, so that static pressure and differential pressure can be transmitted in one transmitter. I made it possible to measure it.

[0019] Furthermore, in order to achieve other purposes, {00
1) When performing anisotropic etching on a silicon wafer using a KOH aqueous solution, etching hardly progresses.
The static pressure detection diaphragm is arranged so that the side in the 110> direction is the closest side, thereby ensuring a desired diaphragm spacing and high withstand pressure.

[0020] In order to achieve the above-mentioned other objects, the shape of the central rigid body portion is made into a polygon having a hexagonal shape or more.

In order to achieve the other objects mentioned above, the surface of the diaphragm for differential pressure detection is etched to make it thinner than the thickness of the diaphragm for static pressure detection, and the diaphragm for differential pressure detection and the diaphragm for static pressure detection are This method uses methods such as processing the diaphragm in the same way. Furthermore, the impurity concentration of the silicon substrate is set to 2×10 18 /cm 3 or less.

[0022]

[Operation] In a composite sensor in which a differential pressure sensor and a static pressure sensor are formed on the same substrate, when a differential pressure is applied, stress is also applied to the static pressure sensor due to the influence of this differential pressure. When a static pressure sensor is formed near a differential pressure sensor, this stress is mainly related to the distance from the differential pressure diaphragm, so if placed without taking this into account, each static pressure sensor will have a different size. Output is generated due to differential pressure. Therefore, the present invention measures static pressure by arranging static pressure sensors so that the stress generated by the differential pressure is equal, and by assembling a bridge to cancel the influence of the differential pressure acting on each static pressure sensor. This is what I did. However, if you combine gauge resistors with the same detection principle to cancel out the effects of differential pressure, the static pressure will naturally be canceled as well, making it impossible to obtain an output voltage. Two types of gauge resistors are provided: a gauge resistor placed on the fixed part to detect static pressure, and a gauge resistor placed on the static pressure detection diaphragm to detect absolute pressure.
By utilizing the fact that when static pressure is applied, the resistance of the gauge resistor placed on the diaphragm is larger than that of the gauge resistor placed on the fixed part, the effect of the differential pressure is canceled out and only the static pressure is detected. This is what I did.

Furthermore, the absolute pressure type static pressure sensor has a large output and a small non-linear error. Furthermore, by combining it with a static pressure sensor that utilizes a difference in elastic modulus as described above, the influence of differential pressure can be offset. In this way, a static pressure sensor with high static pressure detection accuracy is integrated with a differential pressure sensor, and a single transmitter is used to detect differential pressure and static pressure.

[0024]

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is an example of a pipeline system incorporating a flow rate measuring device using the composite transmitter of the present invention.

Differential pressure ΔP generated at both ends of an orifice 560 installed in the middle of a pipeline 550 in a chemical plant, etc.
is measured by the composite transmitter 300 of the present invention, and the flow rate flowing through the pipeline is determined and transmitted to the control device 500. The control device 500 controls a pump that applies pressure to the fluid in the pipeline in accordance with the measured flow rate, and adjusts it so that an appropriate flow rate is sent. Further, the communicator 400 is an input/output device for a person to monitor the state of the system and issue commands to change the control amount, etc.

In this system, if the differential pressure and static pressure can be accurately measured, the accuracy of flow rate detection will be improved and the plant can be operated more efficiently.

[0028] In order to compensate for the effects of fluid compression due to static pressure, conventional systems have provided a pressure transmitter in addition to a differential pressure transmitter in the same pipeline. However, according to this composite transmitter, differential pressure and static pressure can be detected with one unit, so the system can be simplified.

By the way, the composite transmitter 300 of the present invention has a configuration shown in FIG. In this figure, 16 is a composite sensor composed of a differential pressure sensor, a static pressure sensor, a temperature sensor, etc. 102 is a center diaphragm that separates the high pressure side and the low pressure side, 103a and 103b are silicon diaphragms that separate the external environment and the pressure transmission medium (silicone oil, etc.) inside the transmitter and receive external pressure, and 104 is the transmitter body made of SUS or the like. , 105a, 105b are pressure introduction ports,
106 is a signal processing circuit that amplifies the sensor output and performs correction calculations.

As described above, the differential pressure transmitter consists of a pressure receiving part with two liquid chambers, and since the static pressure Ps applied from the high and low pressure sides is as large as 100 atmospheres or more, the difference in the amount of liquid filled in these two liquid chambers is Also, due to the deformation of the pressure receiving part, a minute differential pressure is generated even when the pressures from both sides are equal, causing the output of the differential pressure sensor to fluctuate. This is an error called static pressure effect, and in order to remove this static pressure effect, a sensor is required to independently detect static pressure. However, in the conventional static pressure sensor, the static pressure sensor itself is affected by differential pressure, and it is necessary to correct the influence of this differential pressure. Furthermore, since static pressure sensors and differential pressure sensors are easily affected by changes in temperature, it was also necessary to correct the amount of change due to temperature. Furthermore, since the output of conventional static pressure sensors was small, it was necessary to increase this output. Therefore, in the present invention, by adopting the configuration shown in FIG. 3, accurate static pressure can be detected by removing the influence of the differential pressure applied to the static pressure sensor, realizing a composite sensor with a large static pressure sensor output, and as described below. The differential pressure can now be determined through simple processing.

In FIG. 3(a), the gauge resistor 6 is a static pressure detecting gauge resistor formed on a static pressure detecting diaphragm, and the gauge resistor 5 is a static pressure detecting gauge resistor formed on a fixed part parallel to the gauge resistor 6. This is a gauge resistance for pressure detection. Also, Figure 3
In (e), a gauge resistor 8 is a static pressure detecting gauge resistor formed in a fixed part like the gauge resistor 5, but is formed at right angles to the gauge resistor 6. Gauge resistance 5 and 8
is installed closer to the differential pressure detection diaphragm 9 than the gauge resistor 6.

As shown in FIG.
and 6 are placed at equal distances from the differential pressure diaphragm, the force F due to the differential pressure load is expressed as the cross section A-A' at the position of the gauge resistor 5.
At the position of the gauge resistor 6, the gauge resistor 6 is received at a cross section B-B' which is smaller than A-A', so the gauge resistor 6 on the static pressure detection diaphragm is more is also subject to great stress.

However, the stress acting on the gauge resistor strongly depends on the distance from the differential pressure diaphragm, as shown in FIG. By utilizing this, the gauge resistor 5 on the fixed part is placed closer to the differential pressure diaphragm than the gauge resistor 6 on the static pressure detection diaphragm, and placed in a position where equal stress is applied, as shown in FIG.
The resistance value changes as shown in . In this diagram, gauge resistance 5
and 6 change equally including the sign, and the gauge resistance 8 is 6
It changes with the opposite sign compared to . Therefore, as shown in FIG. 3(b), connect the constant current source 24 and 5, 6 in series, set the voltages V2, V1 between both gauge resistors, and use the subtracter 25 shown in FIG. 3(c). This cancels out the effect of differential pressure. On the other hand, when static pressure is applied, the change in gauge resistance 5 is significantly smaller than the change in gauge resistance 6, so even if subtracted, an output is generated due to the static pressure corresponding to the change in gauge resistance 5. In addition, in FIG. 3(b), the gauge resistance 5 is
When replaced with the gauge resistor 8 shown in (e), this time V1
, V2 exhibit changes of equal magnitude and opposite sign during differential pressure loading. Therefore, in this case, the adder 2 as shown in FIG. 3(d)
6 can cancel out the influence of differential pressure.

The above operation will be explained mathematically. The static pressure sensor is composed of gauge resistors 5 and 6, which are connected as shown in FIG. 3(b). When excited with a constant current I, the output v of the static pressure sensor is

[0035]

[Math 2]

[0036] Here, R50 and R60 are differential pressure ΔP
, the resistance value when static pressure Ps is both 0, and ΔR5 and ΔR6 are the amount of change when differential pressure and static pressure are added. This value is

[0037]

[Math 3]

[0038]

[Math 4]

It is expressed as follows. Here, r, r' are the distances from the end of the differential pressure diaphragm 9 to the center of the static pressure gauge, x, x'
is the distance from the nearest side of the board. 2nd with R5 and R6
The reason why the terms g(x, Ps) and G(x', Ps) are different is
This is because R5 is a static pressure detection gauge resistor placed on the fixed part and uses the difference in elastic modulus, and R6 is an absolute pressure type static pressure detection gauge resistor formed on the static pressure detection diaphragm. ,

[0040]

[Math 5]

There is a relationship shown in equation 5.

Using Equations 3 and 4, if R50 and R60 are formed to be equal to R0 and placed at the positions r=r1 and r'=r2 as shown in FIGS. 16 and 4, the difference is Pressure ΔP
Since the value of the first term that depends on is the same, the equation 2 is canceled out,

[0043]

[Math 6]

As mentioned above, the linear coefficient Δg/ΔPs|Ps=0 and ΔG/ΔPs|Ps=0 of the static pressure Ps
differs greatly between when the gauge resistance is on the static pressure detection diaphragm and when it is on the fixed part. Therefore, if this difference is taken, the differential pressure influence terms f(r, ΔP) and F(r,
ΔP) is removed, and the term due to static pressure remains, so it is possible to construct a static pressure sensor that is not affected by differential pressure.

Next, the detailed configuration of the above composite sensor will be explained using FIG. 5.

FIG. 5(a) is a plan view of the composite sensor.
(b) is a sectional view taken along the line AA in the plan view. Also, (c
) is an example of wiring when the static pressure sensor and differential pressure sensor are connected. In (a), reference numerals 1 to 4 are gauge resistors for differential pressure detection, which are obtained by doping impurities into a semiconductor substrate 10 made of a silicon single crystal by ion implantation or thermal diffusion. These are formed within a region of the diaphragm 9 that has been processed by alkali etching, dry etching, or the like. 5 to 8 are gauge resistors for detecting static pressure, 6 is formed on the static pressure diaphragm 12a, and 7 is formed on another static pressure diaphragm 12b. Also,
Stress is generated in the gauge resistors 6 and 7 due to the differential pressure load. Gauge resistors 5 and 8 are formed at positions where a stress equal to this stress is generated. Gauge resistor 30 is a temperature gauge and is arranged at a fixed part. Further, the temperature gauge 30 is arranged in the <100> direction without sensitivity to stress. 13a to 13f are electrode pads. Figure 5 (
After connecting as in c), apply a constant voltage between 13a and 13b to output differential pressure between 13c and 13d, and output the differential pressure between 13e and 13d.
The configuration is such that static pressure is obtained between f.

Further, reference numeral 11 shown in FIG. 5(b) is a fixing stand for the semiconductor substrate 10 made of borosilicate glass or the like. When a differential pressure is applied to this composite sensor, if gauge resistors 5 and 6 increase their resistance values as shown in FIG. 4, gauge resistors 7 and 8 have equal values and exhibit changes of opposite signs. Therefore, by configuring a bridge circuit as shown in FIG. 5(c), it is possible to obtain a static pressure sensor output that does not vary due to differential pressure.

[0048] In addition, in the conventional static pressure sensor that uses the difference in elastic modulus, the change in resistance value due to a static pressure of about 100 atm is about 0.5%.
However, in this example, since the absolute pressure type static pressure sensor is included, the change in resistance value is reduced by about 10 times to 5.
It is now possible to increase the percentage. That is, the sensitivity to static pressure can be increased approximately 10 times as compared to conventional static pressure sensors that utilize differences in elastic modulus.

With this configuration, the diameter of the static pressure detection diaphragm can be made small, and the influence of the differential pressure acting on the static pressure sensor can be removed, making it possible to accurately measure the differential pressure. , it is possible to realize a small and highly accurate differential pressure detector.

FIG. 6 shows another embodiment of the composite sensor of the present invention.

In this figure, only one diaphragm 12 for static pressure sensor is provided, and gauge resistors 6 and 7 for static pressure detection are provided therein in the same direction. Static pressure outputs from these gauge resistors are obtained from electrode pads 13f and 13e by applying voltage to electrode pads 13a and 13b. With this configuration, only one static pressure diaphragm is required, so
Compared to the example above, processing and wiring are easier and the size can be reduced.

In the above explanation of the composite sensor, no explanation was given regarding the temperature sensor as in the embodiment shown in FIG.
(not shown), a dedicated gauge resistor is disposed on the semiconductor substrate 10 in this embodiment as well to measure changes in resistance due to temperature changes.

FIG. 7 shows another embodiment of the composite sensor of the present invention. In this figure, gauge resistors 5 to 8 for detecting static pressure are arranged in the <100> direction with respect to the diaphragm for detecting differential pressure. With such a configuration, the stress σ based on the differential pressure load acts on the gauge resistances 5 to 8 at an angle of 45 degrees. The resistance change of the gauge is

[0054]

[Math 7]

It is given by: Here, πl is the piezoresistance coefficient in the longitudinal direction, πt is the piezoresistance coefficient in the lateral direction, and σ
l represents stress in the longitudinal direction, and σt represents stress in the transverse direction.

In the case of this embodiment in which the gauges are arranged in the <110> direction, πl=0.5π44, πt=−0.5
π44 (π44 is the shear piezoresistance coefficient), and

[0057]

[Math. 8]

Therefore, by substituting each, ΔR/R=0
becomes. Therefore, according to this embodiment, the influence of the differential pressure load on the static pressure sensor can be offset.

Therefore, in the present invention, processing as shown in FIG. 8 is performed. That is, the static pressure detection diaphragms 12a and 12b are provided closest to the side in the <110> direction of the differential pressure detection diaphragm 9 formed by anisotropic etching. With this arrangement, the differential pressure detection diaphragm 9 and the static pressure detection diaphragms 12a, 12
The distance d between b can be etched with high precision. Therefore,
The adhesive area with the fixing base 11 shown in FIG. 5 can be kept constant, and the yield can be improved.

FIG. 9(a) shows another embodiment of the composite sensor of the present invention.

In this figure, a diaphragm 9 for detecting differential pressure is provided with a central rigid body portion 14 having a thickness substantially equal to the thickness of the chip. Furthermore, anisotropic etching is used to thin the diaphragms 9 and 12, and the shape of the central rigid body portion 14 is made octagonal. When using anisotropic etching Figure 9(b)
Although the rectangular central rigid body surrounded by <111> planes shown in Figure 1 is most likely to be formed, due to the design of the etching mask, it is more than octagonal for {100} plane wafers, and hexagonal or more for {110} plane wafers. A polygonal central rigid body part can be formed. In this way, by making the center rigid body shape hexagonal or more, stress concentration at the corners can be alleviated and the withstand pressure can be improved compared to a square shape.

FIG. 10 shows another embodiment of the composite sensor of the present invention.

This figure shows a region (beam) 1 connecting the differential pressure gauges 1, 4 and 2, 3 from the top surface of the differential pressure detection diaphragm 9.
5 was etched and thinned except for 5.

The sensitivity of the sensor is (diaphragm area)/(
It is almost determined by the thickness of the thin section (plate thickness) 2. Therefore, if the structure is as shown in FIG. 10 and the sensitivity of the differential pressure sensor is kept constant, the diaphragm area will be reduced, and if the sensor chip is made the same size as before thinning, the sensitivity can be improved. Furthermore, by using a beam structure, non-linearity of the differential pressure sensor can be reduced.

Furthermore, if isotropic wet etching is used for etching from the front surface, the front and back surfaces can be etched at the same time, reducing process time. In addition, the corners after anisotropic etching are rounded by isotropic etching, improving breakdown voltage.

FIG. 11 is a diagram showing the relationship between substrate impurity concentration and etching rate when a silicon single crystal {100} plane is anisotropically etched.

As can be seen from this figure, the impurity concentration is reduced to 2.
By setting it to 1018/cm3 or less, high-speed etching can be achieved and the sensor manufacturing time can be shortened.

The composite sensor described above is incorporated into the differential pressure transmitter shown in FIG. 2, and the signal is processed by the signal processing circuit 106 to measure the flow rate and transmitted to the control device 500 shown in FIG. FIG. 12 shows a block diagram of the signal processing circuit 106. Differential pressure of composite sensor 16,
Changes in gauge resistance due to static pressure and temperature are output, selectively taken into the multiplexer 17, and amplified by the programmable gain amplifier 18. Next, the signal is converted into a digital signal by the A/D converter 19 and sent to the microcomputer 21. The characteristics of the differential pressure, static pressure, and temperature sensor are stored in advance in the memory 20, and using this data, the microcomputer 21 corrects the sensor output and detects the differential pressure and static pressure with high precision. The detected differential pressure and static pressure are again converted into analog signals by the D/A converter 22 and output to the control device 500 via the voltage-current converter 23.

Characteristic parts of the above configuration are the memory 20 and microcomputer 21 described below. That is, the characteristics of differential pressure, static pressure, and temperature are stored in advance in the memory 20 as a correction map. The correction map is a three-dimensional representation of the differential pressure sensor output Ed, the static pressure sensor output Es, and the temperature sensor output Et. microcomputer 2
1, processing is performed according to the processing procedure shown in FIG. 13(a). That is, accurate static pressure is determined from the outputs of the static pressure sensor and the temperature sensor using the correction map 202, and this is output. This static pressure output is used to correct the differential pressure output. Next, the temperature of this corrected differential pressure sensor output is corrected using the correction map 203 to obtain an accurate differential pressure output. In conventional composite sensors, the influence of differential pressure was significantly added to the static pressure output, so in order to remove the influence of static pressure, the
As shown in (in other words, it was necessary to correct the influence of the differential pressure acting on the static pressure sensor, and this processing step was necessary). In the present invention, since almost only static pressure can be extracted, processing is also simplified. FIG. 14 shows a flowchart of this correction. First, in S1, the static pressure output Es and the temperature output Et are read, and then in S2, the influence value Ekd on the differential pressure sensor and the temperature-corrected accurate static pressure E are read.
Find s'. Next, the output Ed of the differential pressure sensor is taken in S3, the previously determined influence value Ekd is removed from the output of the differential pressure sensor, and the temperature is corrected from the output Et of the temperature sensor to determine an accurate differential pressure Ed'.

As described above, by using the differential pressure transmitter of the present invention, calculation processing becomes simple, accurate differential pressure and static pressure can be detected, and the device can be miniaturized for flow rate detection in plant systems. have

[0071]

According to the present invention, the influence of the differential pressure appearing on the static pressure sensor can be reduced to almost zero. Therefore, it is not necessary to correct the characteristics due to the influence of differential pressure, and the accuracy of differential pressure measurement can be improved. Furthermore, the correction procedure for static pressure and temperature is simplified, the processing time related to characteristic measurement is shortened, and the control performance of the entire plant is improved.

Further, according to the present invention, since differential pressure and static pressure can be detected with high precision, there is an advantage that the functions of a differential pressure transmitter and a pressure transmitter can be achieved with a single device.

Furthermore, by employing the sensor substrate processing method of the present invention, highly accurate processing can be performed, and the detection accuracy of the sensor can also be improved.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a plant system using an intelligent transmitter of the present invention.

FIG. 2 is an overall configuration diagram of an intelligent transmitter.

FIG. 3 is a diagram explaining the principle of the static pressure detection method of the composite sensor of the present invention.

FIG. 4 is a diagram showing the rate of change in resistance of the static pressure detection gauge when the differential pressure changes.

FIG. 5 is an overall configuration diagram of an embodiment of the composite sensor of the present invention.

FIG. 6 shows another embodiment of the composite sensor of the present invention.

FIG. 7 shows another embodiment of the composite sensor of the present invention.

FIG. 8 is a diagram illustrating a method for manufacturing a composite sensor of the present invention.

FIG. 9 shows another embodiment of the composite sensor of the present invention.

FIG. 10 shows another embodiment of the composite sensor of the present invention.

FIG. 11 is a characteristic diagram of impurity concentration and etching rate of a sensor substrate.

FIG. 12 is a block diagram of a signal processing circuit of the present invention.

FIG. 13 is a block diagram of differential pressure detection.

FIG. 14 is a diagram showing a signal processing flow.

FIG. 15 is a diagram showing the influence of differential pressure on a static pressure sensor.

FIG. 16 is a diagram showing the relationship between the position of the gauge resistance and the influence of differential pressure.

[Explanation of symbols]

1-4... Gauge resistance for differential pressure detection, 5-8... Gauge resistance for static pressure detection, 9... Diaphragm for differential pressure detection, 10... Sensor substrate (etching wafer), 11... Sensor substrate fixing stand,
12...Diaphragm for static pressure detection.

Claims (23)

[Claims] Claims: 1. A composite sensor comprising one sensor substrate on which a plurality of strain-sensitive gauge elements are formed and a fixing base for supporting the sensor substrate, in which, in addition to a differential pressure detection diaphragm formed on the sensor substrate, one A static pressure detecting means is provided with at least one static pressure detecting diaphragm, and is composed of a strain sensitive gauge element formed on the static pressure detecting diaphragm, and a strain sensitive gauge element formed on a fixed part of the sensor substrate. A composite sensor comprising: 2. In claim 1, the strain sensitive gauge element formed on the static pressure detection diaphragm and the strain sensitive gauge element formed on the fixed part are arranged so that the stress due to the differential pressure load is equal in magnitude. A composite sensor characterized by being formed at a working position. 3. In claim 1, the strain sensitive gauge element formed on the fixed part is provided closer to the differential pressure detecting diaphragm than the strain sensitive gauge element formed on the static pressure detecting diaphragm. A composite sensor characterized by: 4. In claim 1, the diaphragm for differential pressure detection is etched to the same depth from the surface opposite to the surface on which the strain-sensitive gauge element is formed as the etching depth of the diaphragm for static pressure detection. A composite sensor characterized by: 5. The composite sensor according to claim 1, wherein the sensor substrate is made of silicon single crystal, and the strain sensitive gauge element is made of a piezoresistive element having a different conductivity from that of the sensor substrate. [Claim 6] A differential pressure sensor provided on one sensor substrate;
In a static pressure detection method using a composite sensor consisting of a static pressure sensor and a temperature sensor, a strain-sensitive strain gauge element formed on a static pressure detection diaphragm provided separately from that for differential pressure detection, and a strain-sensitive strain gauge formed on a fixed part are used. A static pressure detection method for a composite sensor, characterized by processing an output signal with an element and canceling crosstalk due to differential pressure. 7. A strain-sensitive gauge element formed on a differential pressure detection diaphragm provided on one sensor substrate, and a strain-sensitive strain gauge element formed on a static pressure detection diaphragm provided separately from the differential pressure detection diaphragm. It consists of a gauge element, a strain sensitive gauge element formed on a fixed part, and a signal processing means for processing the output signals of the non-sensitive strain gauge element for temperature detection, and is capable of separately detecting differential pressure, static pressure, and temperature. Features a composite sensor. 8. In a composite sensor in which a diaphragm is formed by anisotropically etching a {100} plane single crystal semiconductor substrate, the diaphragm for static pressure detection is arranged in the <100> direction from the center of the diaphragm for differential pressure detection. A composite sensor characterized by an array. 9. A composite transmitter comprising sensing means comprising a strain gauge element for detecting differential pressure and static pressure, and pressure receiving means for protecting the sensing means, wherein the sensing means is a differential pressure detector provided on a sensor substrate. A differential pressure sensing means constituted by a strain sensitive gauge element for detecting differential pressure formed on a diaphragm for detecting differential pressure, and a strain sensitive gauge element formed on a diaphragm for static pressure detection provided separately from the diaphragm for detecting differential pressure and fixed thereto. What is claimed is: 1. A composite transmitter comprising: a static pressure detecting means comprising a strain sensitive gauge element formed on a portion thereof; 10. The composite transmitter according to claim 9, wherein a non-sensitive strain gauge element for detecting temperature is formed on the fixed portion of the sensor substrate. 11. In claim 9, the static pressure detection means comprises a strain sensitive gauge element formed on the static pressure detection diaphragm and a strain sensitive gauge element formed on the fixed part,
A composite transmitter characterized in that these are formed at positions where stress due to differential pressure load acts in an equal magnitude. 12. In claim 9, the strain sensitive gauge element formed on the fixed part is provided closer to the differential pressure detecting diaphragm than the strain sensitive gauge element formed on the static pressure detecting diaphragm. A composite transmitter characterized by: 13. In claim 9, the etching depth of the differential pressure detection diaphragm from a surface opposite to the strain-sensitive gauge element forming surface is the same as the etching depth of the static pressure detection diaphragm. A composite transmitter characterized by: 14. The composite transmitter according to claim 9, wherein the sensor substrate is made of silicon single crystal, and the strain-sensitive gauge element is made of a piezoresistive element having a different conductivity from that of the sensor substrate. . 15. A composite device comprising sensing means comprising a strain gauge element for detecting differential pressure and static pressure, pressure receiving means for protecting the sensing means, and signal processing means for processing the output signal of the sensing means. In the transmitter,
The sensing means includes a differential pressure detecting means composed of a differential pressure sensitive strain gauge element formed on a differential pressure detecting diaphragm provided on a sensor board, and a static pressure detecting means provided separately from the differential pressure detecting diaphragm. What is claimed is: 1. A composite transmitter comprising static pressure detection means comprising a strain sensitive gauge element formed on a diaphragm and a strain sensitive gauge element formed on a fixed part. 16. The signal processing means corrects the influence of temperature change on the output of the static pressure detection means using the output of the temperature detection means, and corrects the influence of the static pressure change on the output of the differential pressure detection means. A composite transmitter characterized in that the correction is performed using the corrected static pressure value, and further the correction is performed using the output of the temperature detection means. 17. In claim 16, the signal processing means comprises a microprocessor and a memory, and the memory records the relationship between static pressure or differential pressure with respect to temperature change as three-dimensional map data, and An intelligent transmitter, characterized in that a processor corrects the detected value of the sensing means based on data recorded in the memory. 18. A method for manufacturing a composite sensor in which a diaphragm is formed by anisotropically etching a {100} plane single crystal silicon wafer, wherein the diaphragm for static pressure detection is arranged in the <110> direction of the diaphragm for differential pressure detection. A method for manufacturing a composite sensor, characterized in that the composite sensor is arranged so as to be closest to the side of the composite sensor. 19. The method of manufacturing a composite sensor according to claim 18, wherein etching is performed so that the static pressure detection diaphragm is disposed diagonally on the sensor substrate. 20. The method of manufacturing a composite sensor according to claim 18, wherein the single crystal silicon wafer has an impurity concentration of 2×10 18 /cm 3 or less. 21. A strain sensitive gauge element formed on a differential pressure detection diaphragm provided on a semiconductor substrate, a strain sensitive gauge formed on a static pressure detection diaphragm, and a strain sensitive gauge formed on a fixed part. A composite sensor comprising a gauge and a non-strain gauge, characterized in that the differential pressure detection diaphragm on the semiconductor substrate is formed in a polygonal shape of hexagon or more. 22. A composite transmitter that measures the flow rate from the pressure difference between both ends of an orifice provided in a pipeline; and a composite transmitter that measures the flow rate in the pipeline based on the measurement results of the composite transmitter and commands from an input/output device. In a plant system consisting of a control device that creates a command signal to an actuator such as a pump so that the pressure becomes a predetermined value, the composite transmitter includes a strain-sensitive gauge element formed on a differential pressure detection diaphragm provided on a sensor board. a static pressure sensor consisting of a strain sensitive gauge element formed on a static pressure detection diaphragm provided separately from the differential pressure detection diaphragm and a strain sensitive gauge element formed on a fixed part; a sensing section comprising a temperature sensor made of a non-sensitive strain gauge element formed on the section; means for correcting changes in the static pressure sensor due to temperature; and means for correcting changes in the differential pressure sensor due to the static pressure and temperature. 1. A plant system comprising: a signal processing section having means for 23. The plant system according to claim 22, wherein the composite transmitter outputs static pressure and differential pressure of the fluid flowing through the pipeline.