JPH0727645A - Capacitive pressure sensor - Google Patents

Abstract

(57) [Summary] [Purpose] The pressure range from low pressure to high pressure is not affected by changes in the atmospheric environment, including problems such as condensation and dust, and there are few measurement errors due to atmospheric pressure fluctuations. Is accurately detected. A first reference chamber 15 is provided between a first substrate 1 and a first diaphragm 20, and a second reference chamber 16 is provided between a second substrate 4 and a second diaphragm 24. The third diaphragm 25 is interposed between the diaphragm 20 and the second diaphragm 24, and the movable parts of these diaphragms are connected by the first and second connecting parts 28 and 29. First
The fixed electrode 3 is arranged on the first substrate 1 in the reference chamber 15 of
The movable electrode 7 is disposed on the first diaphragm 20 so as to face the fixed electrode 3. A vacuum is applied to the first and second reference chambers 15 and 16. The space between the first and third diaphragms 20 and 25 is used as the first pressure introducing chamber 26, the measurement pressure P1 is introduced, and the space between the second and third diaphragms 24 and 25 is made into the second pressure introducing chamber. The atmosphere is opened as 27 (pressure P0).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type pressure sensor.

[0002]

2. Description of the Related Art Conventionally, various types of pressure sensors used in pressure gauges and the like have been known. One of them is a static pressure sensor which detects displacement of a diaphragm shown in FIG. 11 as a capacitance change. There is a capacitance type pressure sensor. This will be schematically described with reference to FIG. 1. Reference numeral 1 is a first substrate made of Pyrex glass, and a concave portion 2 having an appropriate depth is formed in a central portion of a lower surface of the first substrate 1, Further, a fixed electrode 3 is arranged in the recess 2. Reference numeral 4 denotes a second substrate formed of silicon or the like. The second substrate 4 is provided with a thin disk-shaped diaphragm 6 that is sensitive to pressure by removing the central portion of the lower surface by etching.
A movable electrode 7 is embedded and formed on the surface of the diaphragm 6 so as to face the fixed electrode 3. And
The first and second substrates 1 and 4 are superposed on each other and their peripheral portions are integrally joined by anodic bonding to form a sensor element. Reference numeral 8 is a joining portion, and 9 is an atmospheric pressure introducing hole for introducing atmospheric pressure (P0) into the recess 2.

In such a structure, the diaphragm 6
The measured pressure P1 is applied to the back side of the
When 0 is applied, the diaphragm 6 is displaced according to the pressure difference (P1 -P0) at this time, and the gap G between the fixed electrode 3 and the movable electrode 7 is changed (in this case, narrowed). Therefore, the capacitance of the capacitor composed of the fixed electrode 3 and the movable electrode 7 changes, and the measured pressure P1 can be detected by extracting this as an electric signal.

However, in such a conventional electrostatic capacitance type pressure sensor, since the concave portion 2 is open to the atmosphere, it is easily affected by a change in environment and has a drawback that a measurement error occurs. That is, when the environment such as the humidity of the atmosphere changes, the dielectric constant of the air in the recess 2 changes due to the change of the humidity and the like, which changes the capacitance value of the capacitor and causes a measurement error.

Therefore, as a solution to such a problem, there has been proposed an electrostatic capacitance type pressure sensor provided with a reference capacitor in order to eliminate an error factor caused by environmental changes such as humidity (Japanese Patent Laid-Open No. 63-63). 308529
No. This capacitance type pressure sensor includes a sensing capacitor whose capacitance value changes according to the measured pressure, and a reference capacitor whose capacitance value does not change even when the measured pressure changes. Both electrodes of the sensing capacitor and the reference capacitor are provided. By introducing the atmospheric pressure into each of the gaps, an error factor caused by an environmental change such as humidity is removed. The capacitance type pressure sensor with such a structure has an advantage that error factors caused by environmental changes such as humidity can be eliminated, but dew condensation on the capacitor electrode surface or minute dust intrudes into the capacitor electrode. There was a problem that even the measurement error in the case of being unable to be removed. Also, the occurrence of dew condensation is an unavoidable phenomenon when the temperature of the medium for measuring pressure is lower than the atmospheric temperature,
The mixing of dust is also an unavoidable problem as long as the atmospheric pressure introducing hole exists.

In the electrostatic capacitance type pressure sensor, there is an absolute pressure sensor as a sensor capable of completely removing the error factors caused by environmental changes such as humidity including the problems of dew condensation and dust. This absolute pressure sensor is constructed by isolating the gap between the capacitor electrodes, the capacitance value of which changes according to the change of the measured pressure, from the atmosphere and keeping it in a vacuum. For example, JP-A-4-9727 is known. In this type of absolute pressure sensor, since the space between the capacitor electrodes is maintained in a vacuum, the diaphragm provided with one of the electrodes (displaced in response to a change in the measured pressure) is always 1 kg /
The pressure of cm ² is applied, and it is displaced according to the pressure of 1 Kg / cm ² . Therefore, 1Kg / Low pressure than the pressure of cm ^2, for example, 0.01 kg / cm ² about to realize a sensor of the following ranges to the displacement of the diaphragm which is movable electrode is provided is very small, thus There is a problem that the change of the capacitance value is small and accurate measurement becomes very difficult. Further, the output fluctuates according to the atmospheric pressure fluctuation, and the magnitude thereof is about ± 0.05 Kg / cm ^2, which is a highly accurate atmospheric pressure sensor when measuring the pressure in the pressure range below the atmospheric pressure fluctuation. It is very difficult to measure the measurement pressure of 0.01 kg / cm ² range or less with high accuracy without correction.

There is another gas shield sensor as a sensor that can completely eliminate the error factors caused by environmental changes such as humidity including problems such as dew condensation and dust. Although this sensor is isolated from the atmosphere between the capacitors whose capacitance value changes according to the measured pressure, it differs from the absolute pressure sensor in that a gas is enclosed instead of a vacuum. The feature of the gas shield sensor is that the gas pressure between the capacitors can be set close to the atmospheric pressure, and unlike the absolute pressure sensor, one of the electrodes is provided (displaces according to changes in the measured pressure).
It is possible to obtain a state in which almost no pressure is applied to the diaphragm when there is no measurement pressure, and it is possible to achieve a large change in capacitance value with respect to the measurement pressure in the low pressure range compared to atmospheric pressure. . On the other hand, the problem is that the temperature characteristics are very large and complicated temperature correction is required. For example, when the temperature changes from room temperature by plus 50 ° C, the pressure between the capacitors becomes about 1.2 times, that is, a temperature characteristic of about 0.2 Kg / cm ^{2 in} terms of pressure is generated with respect to the change of 50 ° C. become.

[0008]

As described above, in the conventional capacitance type pressure sensor, the pressure range from a slight pressure to a high pressure which is not affected by the change of the atmospheric environment including the problems such as dew condensation and dust. Realizing a sensor was very difficult.

Therefore, the present invention has been made in view of the above points, and an object of the present invention is not to be affected by changes in the atmospheric environment including problems such as dew condensation and dust, and to a large extent. An object of the present invention is to provide an electrostatic capacitance type pressure sensor capable of measuring a pressure range from a slight pressure to a high pressure, with little measurement error due to atmospheric pressure fluctuation.

[0010]

In order to achieve the above object, a first aspect of the present invention relates to a first substrate, a first diaphragm that forms a first reference chamber together with the first substrate, and a second diaphragm. A second diaphragm that faces the first reference chamber together with the substrate and the second substrate to form a second reference chamber that is substantially equal to the bottom area of the first reference chamber; and first and second diaphragms. A third diaphragm that divides the space between them to form first and second pressure introducing chambers having substantially the same bottom area together with these diaphragms; and a fixed electrode arranged on the first substrate in the first reference chamber. A movable electrode disposed on the first diaphragm so as to face the fixed electrode, and the first and third movable electrodes.
A first connecting portion connecting the movable portions of the diaphragm to each other and a second connecting portion connecting the movable portions of the second and third diaphragms to each other, and the first and second reference chambers are The first and second pressure introducing chambers are held in a vacuum and have different sizes, the first connecting portion and the second connecting portion have substantially equal bottom areas, and the movable electrode has the first and second movable portions. The movable electrode is formed to be approximately equal to or smaller than the second connecting portion, and the movable electrode is disposed on the surface of the first diaphragm opposite to the connecting portion side so as to face the fixed electrode. There is something.
According to a second invention, in the first invention, a fixed electrode is provided on the second substrate in the second reference chamber, and a movable electrode is provided on the second diaphragm corresponding to the movable electrode. Is. A third invention is the same as the first or second invention, wherein the first and second substrates and the first, second and third diaphragms are made of the same insulating material. Fourth
According to the invention of 1), in the first or second invention, the first substrate is made of Pyrex glass, and the first, second, and third diaphragms are made of silicon.

[0011]

In the first aspect of the invention, since the first reference chamber is a vacuum, the dielectric constant between the electrodes does not change due to environmental changes such as humidity. Further, since the fixed electrode and the movable electrode are protected by the first diaphragm, the pressure measurement is not affected even when dust or the like is present in the use atmosphere or when the use is performed in the dew condensation atmosphere. Normally, when the first reference chamber is sealed, the capacitance value changes due to fluctuations in atmospheric pressure. Especially in the case of measurement in a low pressure range of 1 kg / cm ² or less, atmospheric pressure fluctuation causes a very large measurement error. However, in the present invention, for example, even if the atmospheric pressure rises (pressures P1 and P0 rise at the same time at the same time), the bottom areas of the first and second reference chambers are substantially equal to each other, and the bottom of the connecting portion is the same. Since the areas are substantially the same, the areas of the movable parts of the first and second diaphragms are the same, and since the bottom areas of the first and second pressure introducing chambers are the same, the diaphragm integral movable part hardly displaces. There is almost no error due to atmospheric pressure fluctuation. In the second invention, since the pressure sensor chip structure has a symmetrical structure, it is difficult for a pressure measurement error to occur due to a change with time of the electrostatic capacitance value when no pressure is applied (when the pressures P1 and P0 are equal). .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a sectional view showing an embodiment of a capacitance type pressure sensor according to the present invention. It should be noted that the same reference numerals are given to the same components as 11 in the drawing.
In the figure, the first substrate 1 is made of Pyrex glass, sapphire, or the like, and has a concave portion 2 having an appropriate depth at the center of the lower surface.
The fixed electrode 3 is disposed on the inner bottom surface of the recess 2. In addition, a first diaphragm 20 that hermetically covers the recessed portion 2 is arranged on the lower surface of the first substrate 1 so that the outer peripheral portion is fixed, whereby a first reference chamber 15 is produced. The movable electrode 7 is provided on the center portion of the movable electrode 20, that is, on the upper surface of the deformable movable portion 20a.
It is arranged corresponding to. The fixed electrode 3 and the movable electrode 7 have substantially the same size, and face each other with a predetermined interval. The first reference chamber 15 is kept in vacuum.

The second substrate 4 is made of silicon, Pyrex glass, sapphire, or the like, and has a recess 23 having an appropriate depth formed at the center of the upper surface. The recess is airtightly covered by the second diaphragm 24. Thus, the second reference chamber 16 is produced. The recess 23 has substantially the same size as the recess 2 of the first substrate 1 and a substantially equal bottom area, and is held in vacuum. A third diaphragm 25 is disposed between the first diaphragm 20 and the second diaphragm 24 with its outer peripheral portion fixed,
With this diaphragm 25, the space between the first and second diaphragms 20 and 24 is divided into two chambers, namely, the first and second chambers.
The pressure introducing chambers 26 and 27 are partitioned. The measurement pressure P1 is introduced into the first pressure introducing chamber 26, and the second pressure introducing chamber 27
Atmospheric pressure P0 is introduced into.

First, second and third diaphragms 2
The movable parts 20a, 24a, 25a of 0, 24, 25 are displaced in conjunction with each other in the same direction when the central parts are connected to each other by the first and second connecting parts 28, 29. First
The connecting portion 28 and the second connecting portion 29 have substantially the same size,
The bottom areas are substantially the same, and are substantially the same as or larger than the fixed electrode 3 and the movable electrode 7. In addition, the first connecting portion 28 and the second connecting portion 29 are the third
The first and second diaphragms 20 and 24 are integrally provided so as to face each other with the diaphragm 25 interposed therebetween. The connecting portions 28 and 29 and the movable electrode 7 are formed with their centers aligned with each other so that the movable electrode 7 does not protrude from the connecting portions 28 and 29. Further, the bottom areas of the first pressure introducing chamber 26 and the second pressure introducing chamber 27 are substantially equal to each other, and the bottom area of the first pressure introducing chamber 26 is formed wider than the bottom area of the first reference chamber 15. Note that the first
The second and third diaphragms 20, 24, 25 are all made of the same material, such as silicon or sapphire.

In the capacitance type pressure sensor having such a structure, the measurement pressure P1 and the atmospheric pressure P0 are introduced into the first and second pressure introducing chambers 26 and 27, respectively, and the movable portion 20a of the first diaphragm 20 is moved. Is A1, the bottom area of the movable portion 24a of the second diaphragm 24 is A1, the bottom area of the movable portion 25a of the third diaphragm 25 is A3, and the bottom areas of the connecting portions 28 and 29 are B. The first diaphragm 20 has a force P1 x (A1 -B) which is displaced toward the substrate 1 side, and the second diaphragm 24 has a force P0 x (A1 -B).
The force displacing to the substrate 4 side of (P1 −P0) × (A3 −B) acts on the third diaphragm 25, and the total force is (P1 −P0) × (A3 −
The force of (A1) displaces the whole diaphragm movable part connected to the substrate 4 side by each connecting part as a unit. Therefore, the capacitance of the capacitor composed of the fixed electrode 3 and the movable electrode 7 changes, and the measured pressure P1 can be detected by extracting this as an electric signal.

Thus, in such a capacitance type pressure sensor, since the first and second reference chambers 15 and 16 are held in vacuum, the fixed electrode 3 is maintained even if the environment such as humidity changes.
The dielectric constant between the movable electrode 7 and the movable electrode 7 does not change, and since the fixed electrode 3 and the movable electrode 7 are protected by the first diaphragm 20, there is no danger of dust or the like adhering to the fixed electrode 3 and the movable electrode 7. However, the pressure measurement is not affected, and therefore the pressure can be accurately detected.

Here, usually the first and second reference chambers 15 and 1
When 6 is sealed, the capacitance value changes due to the fluctuation of the atmospheric pressure P0. Especially in the case of measurement in a low pressure range of 1 kg / cm ² or less, atmospheric pressure fluctuation causes a very large measurement error. However, in the present invention, for example, even if the atmospheric pressure rises (the pressures P1 and P0 rise at the same time at the same time), the bottom areas of the first and second reference chambers 15 and 16 are substantially equal, and they are connected. Since the bottom areas of the portions 28 and 29 are also substantially equal, the areas of the pressure receiving portions of the first and second diaphragms 20 and 24 are equal, and the bottoms of the first pressure introducing chamber 26 and the second pressure introducing chamber 27 are also the same. Since the areas are substantially the same, the areas of the pressure receiving portions are the same above and below the third diaphragm 25, and the integrally movable portions of these diaphragms, that is, the connecting portions 28 and 29 are hardly displaced, and the error due to the fluctuation of the atmospheric pressure is reduced. Occurrence can be prevented.

If the first and second substrates 1, 4, 1, 2 and 3 are made of the same material (silicon, sapphire, etc.), different materials are used. It is possible to reduce the residual stress generated at the time of manufacturing as compared with the case of manufacturing by. Since this change in residual stress over time causes an error in pressure measurement, it is desirable to reduce it as much as possible. Further, the use of a material such as sapphire can prevent the occurrence of parasitic capacitance.

2 to 9 are views showing a manufacturing process of the capacitance type pressure sensor shown in FIG. A large number of electrostatic capacitance type pressure sensors are manufactured in the same manner as semiconductor chips in a 4-inch substrate having a thickness of about 0.5 mm, and the manufacturing procedure of one sensor chip among them will be mainly described. Figure 1 is the first
In the figures showing the steps, a recess 2 is formed in the center of one surface of the first substrate 1 by a method such as wet etching or dry etching. FIG. 3 is a view showing a second step, in which a conductive thin film is formed and patterned in the center of the bottom surface of the recessed portion 2,
The fixed electrode 3 having a predetermined shape is formed. The conductive thin film can be formed by a dry film forming method which is usually used in a semiconductor process, such as CVD, vacuum evaporation, or sputtering. FIG. 4 is a view showing the third step, in which a conductive member is provided at the center of one surface of the first diaphragm 20 with a conductive member
The movable electrode 7 having a required shape is formed by performing film formation and patterning by VD, vacuum deposition, sputtering method, etc.
Thereafter, the fixed electrode 3 and the movable electrode are opposed to each other to bond the first substrate 1 and the first diaphragm 20 in a vacuum or in the atmosphere, and then the interior of the recess 2 is evacuated to evacuate the first reference chamber. Create 15. Further, as a joining method, there are anodic joining, joining with an adhesive, or joining with a method of laminating the joined surfaces with a mirror finish and without interposing foreign matter, depending on the combination of materials. FIG. 5 shows the fourth step, in which the surface of the first diaphragm 20 is polished to a predetermined thickness. Further, it may be thinned by a method such as wet etching or dry etching. FIG. 6 shows a fifth step, in which a predetermined portion of the surface of the first diaphragm 20 is thinned by a method such as wet etching or dry etching to simultaneously manufacture the first pressure introducing chamber 26 and the first connecting portion 28. . FIG. 7 is a diagram showing the sixth step, in which the third diaphragm 25 is joined to the surface of the first diaphragm 20 and then the surface of the third diaphragm 25 is polished to a predetermined thickness. Further, it may be thinned by a method such as wet etching or dry etching. FIG. 8 is a view showing a seventh step, in which the second diaphragm 24 is bonded in vacuum to the second substrate 4 in which the concave portion 23 is formed by the first to sixth steps, and the second reference chamber 16 is formed. Fabricate and second diaphragm 2
4 is made to have a predetermined thickness by a method such as polishing, and then a predetermined portion on the surface of the second diaphragm 24 is made thinner by a method such as wet etching or dry etching to make the second pressure introducing chamber 27 and the second connecting portion. 29 are manufactured at the same time. In this case, it is not necessary to form the fixed electrode and the movable electrode. Figure 9
Is a diagram showing an eighth step. The two sensor chip structures 30 and 31 shown in FIGS. 7 and 8 are overlapped with each other as shown in FIG. 9 to bond the second diaphragm 24 and the third diaphragm 25. Therefore, the manufacturing of the sensor chip is completed. As described above, in the capacitance type pressure sensor according to the present invention, since a large number of sensor chips can be simultaneously manufactured in the substrate similarly to the semiconductor process, mass production of chips of the same quality is possible. is there. This also leads to cost reduction.

FIG. 10 is a sectional view showing another embodiment of the present invention. In this embodiment, the first fixed electrode 3 and the first movable electrode 7 are provided on the first substrate 1 and the first diaphragm 20, and the second fixed electrode 3 and the first movable electrode 7 are provided on the second substrate 4 and the second diaphragm 24. The fixed electrode 33 and the second movable electrode 34 are disposed, and the third diaphragm 25 is sandwiched between them, and the structure is vertically symmetrical. Other configurations are similar to those of the above-described embodiment shown in FIG.

In such a structure, when the capacitance value of the first fixed electrode 3 and the first movable electrode 7 increases, the electrostatic capacitance of the second fixed electrode 33 and the second movable electrode 34 increases. The capacitance value is reduced, and detecting the difference has the advantage of increasing the apparent sensitivity. Further, since the pressure sensor chip structure has a vertically symmetrical structure with the third diaphragm 25 sandwiched therebetween, no pressure is applied (pressure P1
, P0 are equal to each other), there is an advantage that a pressure measurement error due to a change in capacitance value with time is unlikely to occur.

When manufacturing such a capacitance type pressure sensor, the fixed electrode 3 is attached to the second substrate 4 and the second diaphragm 24 by the same steps as those shown in FIGS.
3 and the movable electrode 34 are respectively provided, and the sensor chip structure may be manufactured, and the sensor chip structure shown in FIG.

In the above embodiment, the case where the sensor chip and the first and second reference chambers 15 and 16 are formed in a substantially square shape has been described, but the present invention is not limited to this. Instead, the same effect can be obtained with a rectangular shape or another appropriate shape.

[0024]

As described above, according to the capacitance type pressure sensor of the present invention, it is not affected by the change of the atmospheric environment including the problem of dew condensation, dust, etc. The resulting measurement error is small, the pressure range from low pressure to high pressure can be accurately detected, and the measurement accuracy and durability of the sensor can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a capacitance type pressure sensor according to the present invention.

FIG. 2 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 3 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 4 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 5 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 6 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 7 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 8 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 9 is a diagram for explaining a manufacturing procedure of the capacitance type pressure sensor.

FIG. 10 is a sectional view showing another embodiment of the present invention.

FIG. 11 is a cross-sectional view showing a conventional example of a capacitance type pressure sensor.

[Explanation of symbols]

 1 1st board | substrate 2 concave part 3 fixed electrode 4 2nd board 6 diaphragm 7 movable electrode 8 joint part 9 pressure introduction hole 15 1st reference chamber 16 2nd reference chamber 20 1st diaphragm 23 concave part 24 24th 2 diaphragm 25 3rd diaphragm 26 1st pressure introduction chamber 27 2nd pressure introduction chamber 28 1st connection part 29 2nd connection part

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[Procedure amendment]

[Submission date] September 14, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

In order to achieve the above object, a first aspect of the present invention relates to a first substrate, a first diaphragm that forms a first reference chamber together with the first substrate, and a second diaphragm. A second diaphragm that faces the first reference chamber together with the substrate and the second substrate to form a second reference chamber that is substantially equal to the bottom area of the first reference chamber; and first and second diaphragms. A third diaphragm that divides the space between them to form first and second pressure introducing chambers having substantially the same bottom area together with these diaphragms; and a fixed electrode arranged on the first substrate in the first reference chamber. A movable electrode disposed on the first diaphragm so as to face the fixed electrode, and the first and third movable electrodes.
A first connecting portion connecting the movable portions of the diaphragm to each other and a second connecting portion connecting the movable portions of the second and third diaphragms to each other, and the first and second reference chambers are The first and second pressure introducing chambers are held in a vacuum and have different sizes, the first connecting portion and the second connecting portion have substantially equal bottom areas, and the movable electrode has the first and second movable portions. The movable electrode is formed to be approximately equal to or smaller than the second connecting portion, and the movable electrode is disposed on the surface of the first diaphragm opposite to the connecting portion side so as to face the fixed electrode. There is something.
According to a second invention, in the first invention, a fixed electrode is provided on the second substrate in the second reference chamber, and a movable electrode is provided on the second diaphragm corresponding to the fixed electrode. Is. A third invention is the same as the first or second invention, wherein the first and second substrates and the first, second and third diaphragms are made of the same insulating material. Fourth
According to the invention of 1), in the first or second invention, the first substrate is made of Pyrex glass, and the first, second, and third diaphragms are made of silicon.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Masuda 1-12-2 Kawana, Fujisawa, Kanagawa Yamatake Honeywell Co., Ltd. Fujisawa Plant

Claims (4)

[Claims] 1. A first substrate and a first substrate together with the first substrate.
A first diaphragm forming a reference chamber, a second substrate, and a second reference chamber that faces the first reference chamber together with the second substrate and that is substantially equal to the bottom area of the first reference chamber. The second diaphragm to be formed and a third diaphragm that partitions the space between the first and second diaphragms to form first and second pressure introducing chambers having substantially equal bottom areas together with these diaphragms, and the first reference. The fixed electrode arranged on the first substrate in the chamber, the movable electrode arranged on the first diaphragm facing the fixed electrode, and the movable portions of the first and third diaphragms are mutually arranged. A first connecting portion for connecting,
A second connecting portion that connects the movable portions of the second and third diaphragms to each other, and the first and second reference chambers are held in a vacuum to have a size larger than that of the first and second pressure introducing chambers. However, the first connecting portion and the second connecting portion have substantially the same bottom area, the movable electrode is formed to be substantially equal to or smaller than the first and second connecting portions, and the movable electrode is An electrostatic capacitance type pressure sensor, which is disposed on a surface of the first diaphragm opposite to the connecting portion side and faces the fixed electrode in correspondence with the first connecting portion. 2. The capacitance type pressure sensor according to claim 1, wherein a fixed electrode is provided on the second substrate in the second reference chamber, and the fixed electrode is movable to the second diaphragm corresponding to the movable electrode. An electrostatic capacitance type pressure sensor having electrodes. 3. The capacitance type pressure sensor according to claim 1, wherein the first and second substrates and the first, second and third diaphragms are made of the same insulating material. Characteristic capacitance type pressure sensor. 4. The capacitance type pressure sensor according to claim 1, wherein the first substrate is made of Pyrex glass, and the first, second and third diaphragms are made of silicon. Characteristic capacitance type pressure sensor.