JPH0749280A - Semiconductor differential pressure measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a simple and inexpensive semiconductor differential pressure measuring device with high reliability of overpressure detection. [Structure] A measurement chamber consisting of a predetermined gap space is provided on both sides of the measurement diaphragm whose peripheral edge is fixed, and the measurement diaphragm detects the differential pressure within the allowable measurement range and the measurement diaphragm backs up the wall of the measurement chamber when an overpressure is applied. A semiconductor differential pressure measuring device in which a measuring diaphragm is protected by a first strain detecting element arranged at an edge portion of the measuring diaphragm and an output signal of the first strain detecting element having a phase opposite to that of an output signal of the first strain detecting element at least within an allowable measuring range. A second strain detecting element which is arranged slightly displaced from the center of the measuring diaphragm so that the differential signal from the output signal of the first strain detecting element becomes a monovalent function with respect to the applied pressure. A semiconductor comprising: an overpressure determination unit that differentially detects signals of the first strain detection element and the second strain detection element to determine whether or not an overpressure is applied. It is a differential pressure measuring device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor differential in which a measuring chamber having a predetermined gap is provided on both sides of a measuring diaphragm and the measuring diaphragm is immediately backed up to the wall of the measuring chamber when an excessive pressure is applied. The present invention relates to a semiconductor differential pressure measuring device which is a pressure measuring device, in which a strain detecting element for measuring a differential pressure can be used as it is as an overpressure detecting device, which has high reliability in overpressure detection, and is simple and inexpensive.

[0002]

2. Description of the Related Art FIG. 7 is an explanatory view of the configuration of a conventional example which has been generally used, for example, Japanese Patent Laid-Open No. 59-56137.
It is shown in FIG. In the figure, the housing 1
Flanges 2 and 3 are fitted and assembled on both sides of and are fixed by welding or the like. Both flanges 2 and 3 are provided with a high-pressure fluid inlet 5 of pressure P _H to be measured and pressure P _L.
The low-pressure fluid inlet 4 is provided. Housing 1
A pressure measuring chamber 6 is formed inside the pressure measuring chamber 6
A center diaphragm 7 and a silicon diaphragm 8 are provided inside.

The center diaphragm 7 and the silicon diaphragm 8 are individually fixed to the wall of the pressure measuring chamber 6, and the center diaphragm 7 and the silicon diaphragm 8 are separately fixed.
The pressure measuring chamber 6 is divided into two parts by both. Back plates 6A and 6B are formed on the wall of the pressure measuring chamber 6 facing the center diaphragm 7. The center diaphragm 7 has a peripheral edge portion welded to the housing 1. The silicon diaphragm 8 is entirely formed of a single crystal silicon substrate.

Impurities such as boron are selectively diffused on one surface of the silicon substrate to form four strain gauges 80.
The other side is machined and etched to form a generally concave diaphragm.

The four strain gages 80 are designed so that when the silicon diaphragm 8 is flexed under a pressure difference ΔP, two strain gages are pulled and two are compressed. These strain gages form a Wheatstone bridge circuit. The change in resistance is detected as a change in the differential pressure ΔP. Reference numeral 81 is a lead whose one end is attached to the strain gauge 80. 82
Is a hermetic terminal to which the other end of the lead 81 is connected.

The support 9 is provided with a hermetic terminal, and the silicon diaphragm 8 is adhered and fixed to the end face of the support 9 on the pressure measuring chamber 6 side by a method such as low-melting glass connection. Pressure introducing chambers 10 and 11 are formed between the housing 1 and the flange 2 and the flange 3.

Separating diaphragms 12 and 13 are provided in the pressure introducing chambers 10 and 11, respectively.
A back plate having a shape similar to that of the diaphragms 12, 13 is formed on the walls 10A, 11A of the housing 1 facing the housing 13.

The space formed by the diaphragms 12 and 13 and the back plates 10A and 11A and the pressure measuring chamber 6 are in communication with each other through communication holes 14 and 15. Then, filled liquid 101, 102 such as silicone oil is filled between the diaphragms 12, 13, and the filled liquid reaches the upper and lower surfaces of the silicon diaphragm 8 through the communication holes 16, 17. Although 102 is divided into two by the center diaphragm 7 and the silicon diaphragm 8, it is taken into consideration that the amounts are substantially equal.

In the above structure, when pressure is applied from the high pressure side, the pressure acting on the diaphragm diaphragm 13 is transmitted to the silicon diaphragm 8 by the enclosed liquid 102. On the other hand, when pressure is applied from the low pressure side, the pressure acting on the diaphragm diaphragm 12 is transmitted to the silicon diaphragm 8 by the enclosed liquid 101.

As a result, the silicon diaphragm 8 is distorted according to the pressure difference between the high pressure side and the low pressure side, and the strain amount is electrically taken out by the strain gauge 80, and the differential pressure is measured. . However, in such a device, (1) the pressure on one side of the differential pressure measurement pressure is applied to the periphery of the sensor, and therefore the outside of the sensor must be covered with a pressure resistant container.

(2) A hermetically sealed terminal for taking out an electric signal to the outside is required. (3) Since the sensor is formed by processing the silicon wafer from both sides, the forming process becomes complicated. (4) Since the sensor itself does not have an overpressure protection mechanism, an overpressure protection mechanism is additionally required.

As a solution to this problem, FIG.
Is, for example, Japanese Patent Application No. 4-94151 related to the prior application filed by the applicant of the present application, “Differential pressure measuring device” of the invention, filed on April 14, 1992.

FIG. 9 is a sectional view taken along line AA of FIG. 8, and FIG. 10 is FIG.
FIG. In the figure, the same symbols as those in FIG. 7 represent the same functions. Only parts different from FIG. 7 will be described below.

Reference numeral 21 is a first chamber having a predetermined gap for forming the diaphragm 23 on the silicon substrate 22 and having a very narrow gap. Reference numeral 24 is a first communication hole provided in the silicon substrate 22 and having one end communicating with the first chamber 21. Two
5 is provided on the surface of the diaphragm 23 opposite to the surface on which the first chamber 21 is provided, and has a very shallow depth.

A second chamber 26 is provided in the silicon substrate 22 and communicates with the recess 25 and surrounds the diaphragm 23 in a ring shape except for the first communication hole 24. Reference numeral 27 is a strain detecting element provided on the concave portion 25 side of the diaphragm 23. Reference numeral 28 is a support substrate, one surface of which is connected to the surface of the silicon substrate 22 on which the recess 25 is provided, to form the recess 25, the second chamber 26, and the chamber 29.

As shown in FIG. 11, reference numeral 31 is a wiring which is formed by mixing impurities on the bonding surface of the silicon substrate 22 with the supporting substrate 28 and has one end connected to the strain detecting element 27 and which is made of a conductor. As shown in FIG. 11, reference numeral 32 is an electrode which is provided on the surface of the support substrate 28 that is joined to the silicon substrate 22 and has one end connected to the wiring 31.

Reference numeral 33 is a groove portion provided near the electrode 32 of the silicon substrate 22, as shown in FIG. Groove 3
3 imparts an appropriate spring property to the contact portion of the silicon substrate 22 with the electrode 32, and stably holds the contact between the electrode 32 and the wiring 31.

As shown in FIG. 12, 41 is provided on the silicon substrate 22 so that dust in the fluid as the pressure medium is
This is a filter section that prevents the mixture from entering the chamber 21 or the chamber 29. In this case, two pieces are provided.

By forming the gap d of the filter section 41 sufficiently small by a semiconductor process, dust is prevented from entering. That is, now, the gap d of the filter portion 41 is configured to satisfy d ≦ A−B, where A is the gap distance between the first chambers 21 and B is the displacement amount of the diaphragm 23.

One side of the filter portion 41 has a first communicating hole 2
It is connected to 4. The other side of the filter unit 41 is the second
It communicates with the chamber 29 through the communication hole 42. 51 is
The first pressure guide hole is provided on the support substrate 28, communicates with one of the filter parts 41, and has the other end open to the atmosphere.

Reference numeral 52 is a second pressure guide hole which is provided on the support substrate 28, communicates with the other side of the filter portion 41, and has the other end open to the atmosphere. Reference numeral 53 is a projecting portion connected to the second chamber 26. The overhang portion 53 is configured so that, when a high pressure is applied, the overhang portion 53 receives the high pressure and a large stress is not generated in the joint portion between the silicon substrate 22 and the support substrate 28.

In the above structure, the high pressure side measured pressure is applied to the first chamber 21, and the low pressure side measured pressure is applied to the chamber 29. As a result, the silicon diaphragm 23 is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and the strain amount is electrically detected by the strain detection element 27, and the wiring 31 and the electrode 32.
A signal is taken out via and to measure the differential pressure.

When an excessive pressure is applied to the first chamber 21, the diaphragm 23 is backed up by the wall of the chamber 29. On the other hand, when an overpressure is applied to the chamber 29, the diaphragm 23 is backed up by the wall of the first chamber 21.

Such a device is manufactured as shown in FIGS. 13 to 20. (1) As shown in FIG. 13, silicon 104 is etched by RIE etching on a required portion 102 of the SOI wafer 101, and silicon oxide 1 is etched by a hydrofluoric acid-based etching solution.
03 is etched to etch the silicon oxide 103 and the silicon 104. In this case, silicon oxide 1
03 about 1 μm thick, silicon 104 about 0.5 μ thick
m, the thickness of the silicon of the substrate is about 600 μm.

FIG. 14 is a plan view of FIG. (2) As shown in FIG. 15, an epitaxial growth layer 105 is grown on the surface of the SOI wafer 101. In this case, the thickness of the epitaxial growth layer 105 is about 70 μm.

(3) As shown in FIG. 16, the surface of the epitaxial growth layer 105 is polished to a mirror surface. In this case, about 50 μm is removed. This step determines the thickness of the diaphragm 23. (4) As shown in FIG. 17, the epitaxial growth layer 105
The surface of is etched by RIE etching to form the recess 106. The recess 106 determines the gap of the chamber 29 that determines the movable range of the diaphragm 23 on one side.

(5) As shown in FIG.
A hole 107 for etching the silicon oxide 103,
It is formed by RIE etching or etching with potassium hydroxide.

(6) As shown in FIG. 19, the silicon oxide 103 is etched with an aqueous solution of hydrogen fluoride or hydrogen fluoride gas. (7) As shown in FIG. 20, the silicon substrate 22 is anodically bonded to the support substrate 28 of Pyrex glass.

As a result, (1) since the outside of the differential pressure sensor may be atmospheric pressure, no special pressure vessel is required. (2) A high withstand voltage hermetically sealed terminal for taking out an electric signal to the outside is unnecessary.

(3) Since the silicon wafer can be processed from one side, the forming process becomes simple. (4) Since the sensor itself has an overpressure protection mechanism,
The overpressure protection mechanism is no longer necessary.

[0031]

However, in such a device, as shown in FIG. 21, the strain detecting element 2 is used.
71, 272 are generally on the diaphragm 23,
In order to maximize the sensitivity, the diaphragm 23 and the edge of the diaphragm 23 are arranged at two positions so as to perform a reverse phase operation so as to maximize the sensitivity.

In the differential pressure measuring device of FIG. 8, when an overpressure is applied, the diaphragm 23 is directly subjected to the overpressure, the measurement diaphragm 23 is displaced, and it functions as a measurement chamber over the gap. The wall of the room 21 or 29 is immediately backed up.

Therefore, the strain generated in the strain detecting elements 271, 272 changes non-linearly. FIG. 22 shows the relationship between the detected strain of the strain detecting elements 271, 272 and the applied pressure. A is a distortion curve of the distortion detecting element 271, B is a distortion curve of the distortion detecting element 272, and C is a curve of a difference between the distortion of the distortion detecting element 271 and the distortion of the distortion detecting element 272.

The excessive pressure detection using the strain detecting elements 271, 272 will be examined below. (1) In the case of the strain detecting element 272 arranged at the center of the diaphragm 23, as shown in FIG. 23, when the overpressure is applied in the direction of the arrow D, the diaphragm 23 moves to the first chamber 2
Until it hits the wall No. 1, it becomes tensile strain.

As shown in FIG. 24, a compressive strain occurs after hitting the wall of the first chamber 21. Further, as shown in FIG. 25, the diaphragm 2 backed up by the wall of the first chamber 21.
In the process in which the part of 3 spreads, it becomes a tensile strain. Therefore, in the process of applying the excessive pressure, the strain detecting element 272
As shown in FIG. 26, the detection distortion of changes from increase to decrease to increase.

Therefore, in the strain detecting element 272, when the overpressure is applied, the relationship between the pressure and the strain does not correspond one-to-one. Therefore, as shown in FIG. It is unknown whether the P1 pressure or the P2 pressure is an excessive pressure, and it is impossible to determine whether or not the excessive pressure is applied.

(2) Next, in the case of the strain detecting element 271 arranged at the edge of the diaphragm 23, the strain detecting element 2
The distortion of 71 increases monotonically. Therefore, since the relationship between the pressure and the strain has a one-to-one correspondence, it is considered possible to judge the excessive pressure.

However, considering practical use,
The detected strain of the strain detecting element 271 changes due to static pressure, temperature, etc. in addition to the differential pressure. For example, when a static pressure is applied in addition to the differential pressure, the detected strain of the strain detecting element 271 is offset as shown in FIG. For example, when the strain characteristic curve changes from the E curve to the F curve and the strain value of the overpressure determination is first determined to be ε, the actual overpressure value moves from P3 to P4 and the overpressure determination is performed. Becomes impossible.

(3) Further, in order to cancel the influence of static pressure, temperature, etc., the strain detecting element 271 and the strain detecting element 2
It is conceivable to calculate the difference between the output signals of 72 and use the signal of the calculation result for the overpressure determination. However, with this method, the difference signal between the strain detection elements 271, 272 is
As shown in FIG. 29, the difference between pressure and strain is not 1: 1.

This is because the distortion of the distortion detecting element 271 in the compressive distortion state is rapidly returned.
Even if the difference signal of 1 and 272 is detected, it is considered that the output signal does not monotonically increase (or monotonically decrease) when the excessive pressure is applied. In FIG. 30, the strain detecting elements 271, 27
2 shows the relationship between the strain detected by 2 and the pressure of the overpressure.

With the above three methods, it is difficult to determine a sufficient overpressure. Further, a means of providing an overpressure detection element other than the strain detection elements 271, 272 can be considered, but a new structure or electric circuit for the overpressure detection element is newly required,
The manufacturing process also increases and the manufacturing cost increases.

The present invention solves this problem. An object of the present invention is to provide a simple and inexpensive semiconductor differential pressure measuring device that has high reliability in overpressure detection.

[0043]

In order to achieve this object, the present invention is a semiconductor differential pressure measuring apparatus in which a measuring chamber is provided on both sides of a measuring diaphragm. A first chamber provided between the diaphragm and the diaphragm and having a predetermined gap, a first communication hole provided in the silicon substrate and having one end communicating with the first chamber, and the first chamber of the diaphragm. A recess provided on the surface opposite to the recessed surface, a second chamber that is provided on the silicon substrate and communicates with the recess and surrounds the diaphragm in a ring shape except for the location of the first communication hole, and an overhanging portion. A second communication hole provided in the silicon substrate and having one end communicating with the projecting portion, a strain detecting element provided on the recess side of the diaphragm, and the recess of the silicon substrate are provided. A support substrate having one surface connected to the surface to form the recess, the second chamber, and the chamber; a first strain detection element disposed at an edge portion of the diaphragm on the recess side; and at least within an allowable measurement range. From the center of the measuring diaphragm, an output signal of the opposite phase from the output signal of the first strain detecting element is output so that the differential signal with respect to the output signal of the first strain detecting element becomes a monovalent function with respect to the applied pressure. A second member disposed on the concave side of the diaphragm with a slight deviation
A strain detecting element; and an overpressure determining unit that differentially detects signals of the first strain detecting element and the second strain detecting element to determine whether or not an overpressure is applied. A semiconductor differential pressure measuring device characterized by the above.

[0044]

In the above structure, the high pressure side measurement pressure and the low pressure side measurement pressure are applied to the measurement chambers provided on both sides of the measurement diaphragm, respectively.

As a result, the silicon diaphragm is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and this strain amount is electrically detected by the strain detecting element, and a signal is taken out to the outside via the wiring and the electrode. , The differential pressure is measured.

When an excessive pressure is applied to the diaphragm, it is backed up by the wall of either measurement chamber. Hereinafter, detailed description will be given based on examples.

[0047]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the essential structure of an embodiment of the present invention,
FIG. 2 is a sectional view taken along line CC of FIG. In the figure, the same symbols as those in FIG. 8 indicate the same functions. Only the parts different from FIG. 8 will be described below.

Reference numeral 61 is a first strain detecting element arranged at the edge portion of the measuring diaphragm 23. 62 is shown in FIG.
As shown in, at least within the allowable measurement range, the output signal of the first strain detecting element 61 and the output signal of the opposite phase are output, and the differential signal with respect to the output signal of the first strain detecting element 61 with respect to the applied pressure. Single-valued function (differential signal is 1: 1 against applied pressure)
The second strain detecting element is arranged so as to slightly deviate from the center of the measuring diaphragm 23.

Reference numeral 63 is an overpressure determination means for differentially detecting the signals of the first strain detection element 61 and the second strain detection element 62 to determine whether or not the overpressure is applied.
The overpressure determination means 63 is, for example, as shown in FIG.
The signals of the strain detecting element 61 and the second strain detecting element 62 are
The CPU 65 calculates the difference of the distortion signal, the comparator 66 compares it with the reference signal 67, and outputs the overpressure determination signal 68.

On the other hand, the detection signal 71 of the measured differential pressure is output from the calculation result of the CPU 65.

In the above configuration, the measurement diaphragm 2
A high pressure side measurement pressure and a low pressure side measurement pressure are applied to the measurement chambers 21 and 29 provided on both sides of 3, respectively.

As a result, the silicon diaphragm 23 is distorted according to the pressure difference between the high pressure side and the low pressure side, and the strain amount is electrically detected by the strain detecting elements 61 and 62, and the wiring 3
A signal is taken out via 1 and the electrode 32 to measure the differential pressure.

When an excessive pressure is applied to the diaphragm 23, it is backed up by the wall of one of the measurement chambers 21 and 29. Here, FIG. 5 shows the relationship between the strain detected by the strain detecting elements 61 and 62 and the pressure of the overpressure. FIG. 6 shows the relationship between the difference in detected strain between the strain detecting element 61 and the strain detecting element 62 and the pressure of the excessive pressure.

On the other hand, when the strain detecting element 272 is arranged at the center of the diaphragm 23 as in the conventional example, as shown in FIG.
After hitting the wall of No. 29, the strain shows a characteristic that the strain sharply decreases. However, in the device of the present invention, as shown in FIG. The difference of 1 to 1 corresponds to the applied overpressure).
It is possible to easily determine whether or not the excessive pressure is applied.

In comparison with the strain detecting element 272, the strain detecting element 62 causes a strain returning at one fixed portion of the strain detecting element 62, but a strain returning at the other fixed portion. It is considered that the decrease in the detected strain of the strain detection element 62 is mitigated because it does not exist. Therefore, the difference between the detected strains of the strain detection element 62 and the strain detection element 61 is less likely to increase and decrease, and can be used for determination of excessive pressure.

As a result, the measuring diaphragm 23 is a semiconductor differential pressure measuring device in which the walls 21 and 29 of the measuring chamber are immediately backed up, and one strain detecting element 62 is slightly moved from the center of the diaphragm 23 by a predetermined amount. A semiconductor differential pressure measuring device capable of determining overpressure with high reliability is obtained by calculating the difference in detected strain between the strain detecting elements 62 arranged at the edge of the diaphragm 23 by displacing them. To be

Further, since it is not necessary to additionally use a strain detecting element for judging overpressure, a semiconductor differential pressure measuring device having high reliability, simpleness and low cost can be obtained.
Furthermore, since the arrangement position of the strain detection element only needs to be changed from the conventional example, that is, a slight change such as the etching pattern change of the conventional semiconductor manufacturing process is sufficient, and the know-how of the conventional semiconductor manufacturing process can be utilized. Therefore, a high yield can be obtained as a result. The strain detecting element may be a piezoresistive element or a vibrator type strain detecting element, and any element that can detect strain is essential.

[0058]

As described above, according to the present invention, in a semiconductor differential pressure measuring device in which a measuring chamber is provided on both sides of a measuring diaphragm, a diaphragm is formed on a silicon substrate, and the diaphragm is formed between the silicon substrate and the diaphragm. A first chamber having a predetermined gap, a first communication hole provided in the silicon substrate and having one end communicating with the first chamber, and a first side of the diaphragm opposite to the surface on which the first chamber is provided. A recess provided in the surface, a second chamber that is provided in the silicon substrate and communicates with the recess and surrounds the diaphragm in a ring shape except for the portion of the first communication hole, and an overhanging portion, and the second substrate is provided in the silicon substrate. A second communication hole having one end communicating with the projecting portion, a strain detecting element provided on the concave side of the diaphragm, and one surface connected to the surface of the silicon substrate on which the concave section is provided. A support substrate forming a recess and the second chamber with each other, a first strain detection element arranged at an edge portion of the diaphragm on the recess side, and an output of the first strain detection element at least within an allowable measurement range. A signal that is out of phase with the output signal of the first strain detection element is output, and the differential signal with respect to the output signal of the first strain detection element is slightly displaced from the center of the measurement diaphragm so that the differential signal becomes a monovalent function with respect to the applied pressure. Excessive determination of whether or not an overpressure is applied by differentially detecting the signals of the second strain detection element arranged on the recess side and the first strain detection element and the second strain detection element. A semiconductor differential pressure measuring device comprising a pressure determining means is configured.

As a result, in the semiconductor differential pressure measuring device in which the measuring diaphragm is immediately backed up to the wall of the measuring chamber, one strain detecting element is arranged slightly offset from the center of the diaphragm, and is placed at the edge of the diaphragm. By calculating the difference between the detected strain and the arranged strain detecting element, a semiconductor differential pressure measuring device capable of reliably determining an overpressure can be obtained.

Moreover, since it is not necessary to additionally use a strain detecting element for determining overpressure, a semiconductor differential pressure measuring device having high reliability, simple and low cost can be obtained. Furthermore, since the arrangement position of the strain detection element only needs to be slightly changed from the conventional example, that is, a slight change such as the etching pattern change of the conventional semiconductor manufacturing process is required, and the know-how of the conventional semiconductor manufacturing process can be obtained. It can be used effectively, resulting in a high yield.

The strain detecting element may be a piezoresistive element or a vibrator type strain detecting element, as long as the strain can be detected. Therefore, according to the present invention, it is possible to realize a simple and inexpensive semiconductor differential pressure measuring device that has high reliability in detecting overpressure.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line CC of FIG.

FIG. 3 is a detailed explanatory diagram of a main part of FIG.

FIG. 4 is an explanatory diagram of a main part configuration of an embodiment of the overpressure determination means of FIG.

5 is an operation explanatory diagram of FIG. 1. FIG.

FIG. 6 is an operation explanatory diagram of FIG. 1.

FIG. 7 is an explanatory diagram of a configuration of a conventional example that is generally used in the past.

FIG. 8 is an explanatory diagram of a main part configuration of an embodiment of the invention related to the prior application.

9 is a cross-sectional view taken along the line AA of FIG.

10 is a sectional view taken along line BB of FIG.

FIG. 11 is a detailed explanatory diagram of a main part of FIG. 8;

FIG. 12 is a detailed explanatory diagram of a main part of FIG.

13 is an explanatory diagram of the etching process of FIG.

FIG. 14 is a plan view of FIG.

FIG. 15 is an explanatory diagram of the epitaxial growth process of FIG.

16 is an explanatory diagram of a polishing process of FIG.

FIG. 17 is an explanatory diagram of a recess forming step of FIG.

FIG. 18 is an explanatory diagram of a hole forming process of FIG.

FIG. 19 is an explanatory diagram of the etching process of FIG. 8.

20 is an explanatory diagram of a joining process of FIG.

21 is a detailed explanatory diagram of a main part of FIG. 8. FIG.

22 is an explanatory diagram of the operation of FIG. 21. FIG.

FIG. 23 is an operation explanatory diagram of FIG. 21;

FIG. 24 is an operation explanatory diagram of FIG. 21;

FIG. 25 is an explanatory diagram of the operation of FIG. 21.

FIG. 26 is an explanatory diagram of the operation of FIG. 21.

27 is an explanatory diagram of the operation of FIG. 21. FIG.

FIG. 28 is an explanatory diagram of the operation of FIG. 21.

FIG. 29 is an explanatory diagram of the operation of FIG. 21.

FIG. 30 is a diagram illustrating the operation of FIG. 21.

[Explanation of symbols]

 21 ... 1st chamber 22 ... Silicon substrate 23 ... Diaphragm 24 ... 1st communicating hole 25 ... Recessed part 26 ... 2nd chamber 27 ... Strain detecting element 28 ... Support substrate 29 ... Chamber 31 ... Wiring 32 ... Electrode 41 ... Filter part 42 ... 2nd communicating hole 51 ... 1st pressure guide hole 52 ... 2nd pressure guide hole 53 ... Overhang part 61 ... 1st distortion detection element 62 ... 2nd distortion detection element 63 ... Excessive pressure determination means 64 ... Counter 65 ... CPU 66 ... Comparator 67 ... Reference signal 68 ... Overpressure determination signal 71 ... Detection signal 101 ... SOI wafer 102 ... Required part 103 ... Silicon oxide 104 ... Silicon 105 ... Epitaxial growth layer 106 ... Recess 107 ... Hole

Claims (1)

[Claims] 1. A semiconductor differential pressure measuring device in which a measuring chamber is provided on both sides of a measuring diaphragm, wherein a diaphragm is formed on a silicon substrate, and the diaphragm is provided between the silicon substrate and the diaphragm. A chamber; a first communication hole provided in the silicon substrate and having one end communicating with the first chamber; a recess provided on a surface of the diaphragm opposite to a surface on which the first chamber is provided; A second chamber that is provided in the substrate and communicates with the recess, and surrounds the diaphragm in a ring shape except for the portion of the first communication hole, and a projecting portion; A communication hole, a strain detecting element provided on the side of the recess of the diaphragm, and one surface connected to the surface of the silicon substrate on which the recess is provided to form the recess and the second chamber. A supporting substrate, a first strain sensing element arranged at an edge portion of the diaphragm on the concave side, and outputs an output signal having a phase opposite to that of the output signal of the first strain sensing element at least within an allowable measurement range. A second strain detector disposed on the concave side of the diaphragm slightly displaced from the center of the measuring diaphragm so that the differential signal with the output signal of the first strain detecting element becomes a monovalent function with respect to the applied pressure. An overpressure determination unit for differentially detecting signals from the first strain detection element and the second strain detection element to determine whether or not an overpressure is applied. And semiconductor differential pressure measuring device.