JP2002267559A - Capacitive pressure sensor, sensor element, and method of manufacturing sensor element - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent the electrodes from adhering to each other even if the strain-generating part of the diaphragm is displaced in the atmosphere and displace the strain-causing part, to facilitate the handling during manufacture and shipping, and to obtain a wide pressure range. And the effect of temperature change is small, and the temperature characteristics are improved. SOLUTION: A movable plate 25 is joined to a surface of a diaphragm 23 on a vacuum chamber 31 side and a center of a strain generating portion 23A,
The outer peripheral portion of the movable plate 25 and the diaphragm 23
Are fixed to each other so as to approach each other, and a movable electrode 27 and a fixed electrode 26 are formed on these opposing surfaces, so that the substrate 21, the holding member 22, and the diaphragm 23 are formed.
The enclosed space surrounded by is evacuated to a vacuum chamber 31.

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 having a diaphragm structure for detecting a change in measured pressure as a change in capacitance, and more particularly to a capacitance for absolute pressure measurement having a vacuum chamber. The present invention relates to a pressure sensor, a sensor element, and a method for manufacturing a sensor element.

[0002]

[Prior art]

Hitherto, various types of capacitance type pressure sensors used for pressure gauges and the like have been known. One of them is a capacitance type pressure sensor for measuring an absolute pressure (hereinafter, such a sensor is referred to as an absolute pressure sensor). This absolute pressure sensor isolates the gap between the capacitor electrodes, whose capacitance value changes due to a change in the measured pressure, from the atmosphere and evacuates the inside, and is usually configured as shown in FIG. In brief, the absolute pressure sensor 1 is composed of an anodically bonded silicon substrate 2 and a glass substrate 3.
And a vacuum chamber 4 is formed between the two substrates.
The silicon substrate 2 is provided with a thin-walled strain-generating portion 2A that is elastically deformed when it receives a measured pressure P1.
A movable electrode 5 is provided on the surface side of A. Movable electrode 5
Is electrically connected via a lead wire 8 to a capacitance detection IC chip 7 provided on the surface of the glass substrate 3. On the other hand, on the surface of the glass substrate 3 facing the strain generating portion 2A,
A fixed electrode 6 is provided.

In the conventional absolute pressure sensor 1 having such a structure, when a measured pressure P1 is applied to the back side of the strain generating portion 2A, the strain generating portion 2A is elastically deformed in accordance with the pressure, and the movable electrode 5 The minute gap G between the electrode and the fixed electrode 6 changes. For this reason, the capacitance of the capacitor composed of the movable electrode 5 and the fixed electrode 6 changes, and this is taken out as an electric signal and subjected to signal processing, whereby the measured pressure P1
Can be detected.

[0005]

In the above-described conventional absolute pressure sensor 1, the pressure receiving surface on the measurement pressure side of the strain generating portion 2A is at atmospheric pressure after manufacturing or shipping. In this case, in the element for the low pressure range, since the distance between the electrodes is extremely small, the strain generating portion 2A is elastically deformed toward the vacuum chamber 4 due to the atmospheric pressure, and the movable electrode 5 comes into close contact with the fixed electrode 6. For this reason, there is a problem that the strain-flexing portion 2A does not return to the state before the maximum deformation even when it is attached to an instrument or the like, and becomes unusable. In addition, the conventional pressure sensor has the movable electrode 5 when not measuring.
And the fixed electrode 6 are separated from each other at the maximum, and the measured pressure P1
This causes the strain generating portion 2A to elastically deform toward the glass plate 3 to reduce the distance between the electrodes, so that the amount of deformation of the strain generating portion 2A is determined by the distance between the electrodes when no measurement is performed. In other words, there is a problem that the pressure range is determined by the distance between the electrodes during non-measurement, and a wide pressure range cannot be obtained. Further, since the movable electrode 5 is provided on the strain generating portion 2A,
Although it is a relative problem, the thickness of the electrode and the thickness of the substrate where the electrode is formed become a problem. That is,
When the strain generating portion 2A expands and contracts due to a temperature change, the distance between the electrodes changes, resulting in a measurement error.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to make it possible for electrodes to adhere to each other even if a strain-generating portion of a diaphragm is elastically deformed by atmospheric pressure. Another object of the present invention is to provide a capacitance-type pressure sensor that can be easily manufactured and shipped, can have a wide pressure range, is less affected by temperature changes, and has improved temperature characteristics.

[0007]

According to a first aspect of the present invention, there is provided a diaphragm including a diaphragm constituting a part of a vacuum chamber, and detecting an elastic deformation of a strain generating portion of the diaphragm as a change in capacitance. In the sensor element of the capacitance type pressure sensor, a central portion forms a strain generating portion, and a portion outside the strain generating portion forms a fixing portion, and a pressure introducing hole, and a fixing portion of the diaphragm is provided. A cover plate forming a pressure introduction chamber together with the diaphragm by being joined, and a movable plate having an electrode forming portion and a connecting portion integrally projecting from the center of the electrode forming surface of the electrode forming portion, A connection portion of the movable plate is joined to a surface opposite to the cover plate at the center of the strain generating portion of the diaphragm, and a fixed portion of the diaphragm and an electrode shape of the movable plate are joined. It is obtained by forming by opposed fixed electrode and the movable electrode part.

In the present invention, when the strain generating portion of the diaphragm is elastically deformed, the movable plate is also displaced integrally with the strain generating portion, thereby changing the distance between the electrodes.

[0009] The second invention is the above-mentioned first invention, wherein:
The diaphragm, the cover plate, and the movable plate are formed of the same material, respectively, and are integrally joined by direct joining.

In the present invention, since the diaphragm and the movable plate are directly joined, a sensor element having a desired inter-electrode distance can be obtained. That is, in the method of joining using a joining material, the inter-electrode distance varies due to variation in the thickness of the joining material itself after joining. On the other hand, direct bonding is a method in which the bonding surfaces of the bonding members are mirror-finished and bonded to each other simply by bringing them into close contact with each other. Therefore, there is no need to use a bonding material, and therefore, variations in the distance between the electrodes due to variations in the thickness of the bonding material are reduced. This does not occur, and a highly accurate inter-electrode distance can be obtained. In the case of direct joining, a large pressing force is not required, and basically, it is only necessary to laminate each other. However, in order to obtain a more reliable joining, it is necessary to heat at an appropriate temperature (about 200 to 1300 ° C.). preferable. Further, since they are formed of the same material, no stress is generated due to a difference in the coefficient of thermal expansion.

According to a third aspect of the present invention, there is provided an electrostatic capacitance type pressure sensor which includes a diaphragm constituting a part of a vacuum chamber and detects an elastic deformation of a strain generating portion of the diaphragm as a change in capacitance. A cover plate that forms a pressure introduction chamber together with the diaphragm by covering a pressure receiving surface of the diaphragm, and a frame-shaped holding portion that sandwiches the outer peripheral edge of the diaphragm together with the cover plate, A substrate forming the vacuum chamber; an electrode forming portion; and a connecting portion integrally protruding at the center of the electrode forming surface of the electrode forming portion. The connecting portion is strained on the surface of the diaphragm on the vacuum chamber side. A movable plate joined to the center of the portion, the diaphragm, the cover plate and the movable plate constitute a sensor element, The fixed electrode and the movable electrode peripheral edge portion of the serial diaphragm and the electrode formation surface of the movable plate in which is provided so as to face each other.

According to the present invention, when a measured pressure is introduced into the pressure introducing chamber, the strain-generating portion of the diaphragm is elastically deformed, and the movable plate is also displaced integrally therewith, thereby changing the distance between the electrodes. Since the deformation direction of the strain generating portion is a direction away from the cover plate, in other words, a direction in which the distance between the electrodes is increased, the fixed electrode and the movable electrode do not adhere to each other, and the pressure range can be widened. . Further, since the fixed electrode is provided on the fixed portion of the diaphragm, the fixed electrode is not affected by expansion and contraction of the strain generating portion due to a temperature change.

[0013] In a fourth aspect based on the third aspect,
A hole for reducing the weight is provided in the electrode forming portion of the movable plate.

In the present invention, since the weight of the movable plate is reduced, it is less affected by gravity and acceleration. In other words, since the movable plate is suspended by the strain-causing part of the diaphragm, it is easily affected by gravity and acceleration due to its own mass. And the restrictions on the vibration characteristics and the attitude of the sensor are eliminated. Non-through holes or through holes can be considered as the holes for reducing the weight.

According to a fifth aspect of the present invention, in the third or fourth aspect, an overload preventing portion for restricting displacement of the movable plate is provided on the substrate.

According to the present invention, since the overload preventing portion limits the displacement of the movable plate, the strain generating portion of the diaphragm is prevented from being deformed to a predetermined amount or more and damaged when an overload is applied. As the overload prevention portion, a projection, a step surface, or the like can be considered.

According to a sixth aspect of the present invention, the third, fourth or fifth aspect is provided.
In the invention, the cover plate has a concave portion for the pressure introduction chamber, and the diaphragm is formed in a thin plate shape having a constant thickness, and the outer peripheral edge is fixed to the cover plate by being joined to the cover plate. And a portion inside the fixed portion forms a strain generating portion, and a fixed electrode is formed on a surface of the fixed portion on the vacuum chamber side.

In the present invention, since the diaphragm material can be formed by polishing, the formation of the diaphragm is easy. When the diaphragm is joined to the cover plate, a portion corresponding to the concave portion becomes a strain generating portion, and an outer portion therefrom becomes a fixing portion.

In a seventh aspect based on the third, fourth, fifth or sixth aspect, the diaphragm, the cover plate and the movable plate are formed of the same material, respectively, and are integrally joined by direct joining. This constitutes a sensor element.

In the present invention, the distance between the electrodes can be accurately determined as designed. That is, when joining is performed using a joining material, the inter-electrode distance varies due to variation in the thickness of the joining material itself after joining,
It is difficult to obtain a highly accurate inter-electrode distance. On the other hand, in the case of direct joining, since the joining surfaces of the joining members are mirror-finished and joined to each other simply by being brought into close contact with each other, there is no need to use a joining material. The distance between the electrodes can be obtained.

In an eighth aspect based on the seventh aspect, the diaphragm, the cover plate and the movable plate are formed of sapphire or quartz.

In the present invention, the diaphragm has excellent corrosion resistance and can be brought into direct contact with the fluid to be measured.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a sensor element in a capacitance type pressure sensor which includes a diaphragm constituting a part of a vacuum chamber and detects elastic deformation of a strain generating portion of the diaphragm as a change in capacitance. A step of forming a diaphragm with a diaphragm material, a step of forming a cover plate having a pressure introduction hole with a plate material, and integrally joining an outer peripheral edge of the cover plate formed in the step and the diaphragm. A step of setting the outer peripheral edge of the diaphragm as a fixed portion, and a portion inside the fixed portion as a strain-flexing portion, and a fixed electrode on the outer peripheral edge of the surface opposite to the cover plate side in the fixed portion of the diaphragm. Forming and removing the electrode on one side of the movable plate material other than the center by etching A step of forming a connection portion to be joined to the diaphragm by an unetched portion, and a step of forming a movable plate by forming a movable electrode on the electrode forming surface of the electrode forming portion of the movable plate material; And joining the connecting portion of the movable plate to the center of the strain generating portion of the diaphragm.

In the present invention, the movable plate is displaced integrally by the elastic deformation of the strain generating portion of the diaphragm,
A sensor element in which the distance between the electrodes changes is formed.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a sensor element in a capacitance type pressure sensor which includes a diaphragm constituting a part of a vacuum chamber, and detects elastic deformation of a strain generating portion of the diaphragm as a change in capacitance. In, a step of forming a diaphragm having a constant thickness by a diaphragm material, a pressure introduction hole by a plate material, a step of forming a cover plate having a recess for a pressure introduction chamber,
A step of integrally joining an outer peripheral edge of the diaphragm and the cover plate formed in the above step to form an outer peripheral edge of the diaphragm as a fixed portion, and a portion inside the fixed portion as a strain-flexing portion; A step of forming a fixed electrode on the outer peripheral edge of the surface opposite to the cover plate side in the fixed portion, and an annular separating groove larger than the strain generating portion of the diaphragm on one surface of the movable plate material; Forming a pin insertion hole located outside the separation groove, and forming an electrode forming portion by removing a portion of the movable plate material inside the separation groove in an annular shape by dry etching on the one surface. Forming a connection portion joined to the diaphragm by an unetched portion; and forming a movable electrode on an electrode forming surface of the electrode forming portion of the movable plate material. Joining a portion of the movable plate material outside of the connecting portion and the separation groove to a strain generating portion and a fixed portion of the diaphragm, and dry-etching a surface of the movable plate material on a side opposite to the diaphragm side. Forming the holding portion of the substrate and the movable plate by separating the movable plate material into portions outside and inside the separation groove by removing a predetermined depth by removing the closed end of the separation groove. It is provided with.

In the present invention, the fixed portion of the diaphragm and the strain generating portion are formed by joining the diaphragm and the cover plate. Further, the movable plate and the holding portion of the substrate are formed simultaneously by one movable plate material.

According to an eleventh aspect, in the tenth aspect, the movable plate material is the same as the first plate material having the annular first separating groove formed on the joint surface. And a second plate material formed directly on the joining surface with the first plate material and having a second annular separation groove formed on the joining surface with the first plate material. A communication groove for connecting the first separation groove and the second separation groove to each other is formed on a joint surface of the second plate material.

In the present invention, since the first and second separation grooves are not located on the same straight line, when the movable plate material is dry-etched, the fixed electrode formed on the diaphragm is not etched. .

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is an external perspective view showing an embodiment of a capacitance type pressure sensor according to the present invention,
2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a sectional view taken along the line III-III of FIG.
4 is a plan view of a fixed electrode, and FIG. 5 is a plan view of a movable electrode. In these figures, the reference numeral 21 denotes a substrate, 22 denotes a frame-shaped holding member (holding portion), 23 denotes a diaphragm, 24 denotes a cover plate, 25 denotes a movable plate, 26 denotes a fixed electrode, 27 denotes a fixed electrode, and 28 denotes a movable electrode. Numerals denote electrode extraction pins, which constitute a capacitance type pressure sensor (hereinafter referred to as absolute pressure sensor) 20 for measuring absolute pressure.

The substrate 21, the holding member 22, the diaphragm 23 and the cover plate 24 are sequentially laminated so that their centers are aligned, and are integrally joined. Movable plate 2
5 is integrally joined to the center of the back surface of the diaphragm 23. Diaphragm 2 provided with fixed electrode 26
3. The movable plate 25 provided with the cover plate 24 and the movable electrode 27 is formed of the same material and constitutes the sensor element S. The substrate 21 and the holding member 22 form a housing of the sensor element S.

The substrate 21 is made of sapphire, quartz or alumina ceramics, and has a square recess 30 at the center of the upper surface. The recess 30 is formed by the inner surface of the holding member 22 and the back surface of the diaphragm 23. The movable plate 25 is housed in the enclosed closed space 31. The sealed space 31 is evacuated to form a vacuum chamber having a predetermined degree of vacuum. For this reason, the substrate 21 is provided with a vacuum exhaust pipe 32 penetrating between the inside and the outside, and the vacuum exhaust pipe 32 is evacuated from the sealed space 31 to form a vacuum chamber.
Crush and close.

The substrate 21 has two pin insertion holes 33 located on both sides of the vacuum chamber 31 and penetrating the front and back surfaces. The electrode extraction pins 28 pass through these pin insertion holes 33. It is provided.

The holding member 22 is formed in a square frame shape, and a rectangular concave portion 34 is formed on the inner surface of the upper end portion over the entire circumference, so that the upper end portion is a thin portion 22A and the lower end portion is a thick portion 22B. Is joined to the upper surface of the substrate 21 by brazing or the like. A plurality of electrode holes 35 are formed through the thick portion 22B, and the electrode extraction pins 28 are provided through the electrode holes 35. The inner end of the electrode extraction pin 28 is connected to the fixed electrode 26 by solder or the like. This soldering
This is performed by pouring the molten solder into the pin insertion holes 33 and the electrode holes 35 to be solidified. Furthermore, the thick part 2
On the upper surface of 2B, that is, on the bottom surface of the concave portion 34, a reference electrode 36 is formed. The reference electrode 36, like the fixed electrode 26 and the movable electrode 27,
It is formed by vapor deposition or sputtering.

The diaphragm 23 forms the vacuum chamber 31 together with a housing composed of the substrate 21 and the holding member 22. The diaphragm 23 is formed of an extremely thin rectangular plate having a constant thickness, and the central portion has a strain generating portion 23A. Used as
A portion outside the strain generating portion 23A is used as a fixing portion 23B. The strain generating portion 23A is circular, and the upper surface has a measured pressure P
1 is formed, and the movable plate 25 is joined to the center of the back surface. The upper surface of the fixing portion 23B forms a bonding surface with the cover plate 24, and the outer peripheral edge of the back surface is bonded to the upper surface of the thin portion 22A of the holding member 22, and the fixed electrode 26 is formed on the inner side thereof. The reference electrode 39 is formed. Reference electrode 3
9 is provided outside the fixed electrode 26, and the holding member 2
Opposite and opposed to the reference electrode 36 provided on the second side.

As shown in FIG. 4, the fixed electrode 26 is composed of two electrodes 26A and 26B opposed to each other with a strain generating portion 23A of the diaphragm 23 interposed therebetween. Each electrode 2
6A and 26B have a shape in which a pattern having a square outer shape and a circular inner shape is divided into two, and a wiring portion 40 is extended on one side surface, and a pad portion 41 provided at a tip portion thereof has a pad portion 41 for extracting the electrode. The inner ends of the pins 28 are connected by soldering. Although the two electrodes 26A and 26B have the same shape, they are positioned so as to be point-symmetric.

Here, in the present embodiment, an example has been shown in which the strain-generating portion 23A of the diaphragm 23 is formed in a circular shape in order to increase the area of the fixed electrode 26. Good.

The cover plate 24 is a square plate having the same size as the holding member 22 and the diaphragm 23. A pressure introducing hole 44 for guiding the measured pressure P1 to the pressure receiving surface 38 of the diaphragm 23 is provided at the center. The fixing portion 23B of the diaphragm 23 is joined to the back surface side. Also, the cover plate 24
Are formed at the center of the front and back surfaces, respectively. The concave portion 46 on the back side is formed of a circular concave portion, which defines the outer edge of the strain generating portion 23A of the diaphragm 23, and the pressure P to be measured between the strain generating portion 23A and the strain generating portion 23A.
A pressure introduction chamber 51 into which 1 is guided is formed.

The movable plate 25 is mounted on the fixed electrode 2.
6 is formed of an electrode forming portion 25A formed of a square plate slightly smaller than the outer shape, and a connection portion 25B integrally projecting from the upper surface of the electrode forming portion 25A, that is, the center of the surface facing the diaphragm 23. ing. Electrode forming part 25A
Forms an electrode forming surface 47, and this electrode forming surface 47
The movable electrode 27 is formed on the outer peripheral edge of the fixed electrode 26 so as to face the fixed electrode 26 with a predetermined inter-electrode distance. A plurality of holes 48 for reducing the weight are formed inside the movable electrode 27 so as to reduce the mass of the movable plate 25 and make it less affected by gravity and acceleration. The hole 48 is not limited to a through hole and may be a non-through hole. The upper surface of the connection portion 25B forms a bonding surface 49, and is bonded to the center of the back surface of the strain-flexing portion 23A of the diaphragm 23. The movable plate 25 is formed simultaneously with the holding member 22 (this point will be described later), and is joined to the diaphragm 23 together with the holding member 22.

As shown in FIG. 5, the movable electrode 27 has an outer shape equal to the outer shape of the movable plate 25 and an inner shape formed in a circular pattern having substantially the same size as the strain generating portion 23A of the diaphragm 23. , And opposed to the fixed electrode 26 while keeping a very small gap.

The holding member 22, the diaphragm 23, the cover plate 24 and the movable plate 25 are formed of the same material, for example, sapphire substrate (Al ₂ O ₃ ) or quartz, and are integrally joined by direct joining. It constitutes the sensor element S. Direct joining is a method of joining only the physicochemical bonding force between joining members without using any joining material, etc., and a method of joining by joining mirror surfaces of two joining members and bringing them into close contact with each other. It is. At the time of joining, there is no particular need to apply pressure, and it is sufficient to simply overlap them. However, it is more preferable to join by heating to about 200 to 1300 ° C.

In such an absolute pressure sensor 20, when the measured pressure P1 is guided to the pressure introducing chamber 51 and applied to the pressure receiving surface 38 of the strain generating portion 23A at the time of measurement, the strain generating portion 23A responds to the measured pressure P1. It is elastically deformed toward the vacuum chamber 31 side. For this reason, the movable plate 25 is also connected to the strain generating portion 23 of the diaphragm 23.
A is displaced toward the vacuum chamber 31 together with A, and the distance between the fixed electrode 26 and the movable electrode 27 increases. Therefore, the capacitance of the capacitor formed by the fixed electrode 26 and the movable electrode 27 changes, and by extracting this as an electric signal, the measured pressure P1 can be detected.

As described above, when the diaphragm 23 is elastically deformed in the direction in which the distance between the fixed electrode 26 and the movable electrode 27 is increased by the measured pressure P1, as shown in FIG. When the pressure introduction chamber 51 is open to the atmosphere, the strain generating portion 23A of the diaphragm 23 is elastically deformed toward the vacuum chamber 31 by the atmospheric pressure Po, so that the conventional pressure sensor 1 shown in FIG. Unlike this, a situation in which the movable electrode 27 is in close contact with the fixed electrode 26 does not occur, and the movable electrode 27 does not become unusable. Therefore, handling of the pressure sensor 20 at the time of manufacture and shipping is easy.

The holding member 22, the diaphragm 23,
When the cover plate 24 and the movable plate 25 are formed of the same material, the residual stress generated at the joint during the manufacture can be reduced as compared with the case where the cover plate 24 and the movable plate 25 are manufactured of different materials.
Since the change with time of the residual stress causes an error in pressure measurement, it is desirable to reduce the change as much as possible. Further, even if there is a temperature change or the like during use, no thermal stress is generated at the joint, and the elastic deformation of the diaphragm 23 is not affected.
Therefore, it is possible to provide a capacitance type pressure sensor which has excellent temperature characteristics and can perform highly accurate measurement.

Further, since the diaphragm 23, the cover plate 24 and the movable plate 25 are integrally joined by direct joining, a highly accurate distance between electrodes can be obtained.
That is, when bonding is performed using a bonding material, the inter-electrode distance varies due to variations in the thickness of the bonding material. However, in the case of direct bonding, no variation is caused by the thickness of the bonding material because no bonding material is used. This does not occur, and the dry etching amount of the cover plate 25 and the fixed electrodes 26,
The distance between the electrodes is determined only by the thickness of the movable electrode 27. Therefore, it is possible to obtain an interelectrode distance substantially equal to the design value, and to obtain an electrostatic capacitance type pressure sensor capable of performing highly accurate and highly reliable pressure measurement.

When each component of the sensor element S is formed of a sapphire substrate, sapphire is a single crystal and has no grain boundaries such as alumina and ceramics. The pressure can be measured by directly contacting even a highly corrosive fluid to be measured such as a liquid. Therefore, it is not necessary to cover the surface of the sensor element S with the sealed liquid or the like to isolate the sensor element S from the fluid to be measured.

Further, sapphire can manufacture several hundred sensor elements by adopting a manufacturing process similar to a batch process used for semiconductors, and is excellent in mass productivity. That is, a large number of cover plates are formed on one cover plate material by the above-described steps. Also, a large number of diaphragms are formed on one diaphragm material. Further, many movable plate materials are formed on one movable plate material. A large number of sensor elements are formed by laminating these plate materials and joining them directly to each other. Thereafter, these sensor materials are cut out by dicing. As a result, variation between sensor elements such as electrode spacing is small, and a large number of sensor elements having the same characteristics can be manufactured.

Further, since the reference electrodes 36 and 39 whose capacitance value does not change even when the measured pressure P1 changes are provided, the capacitance by this reference electrode and
By comparing the capacitance between the fixed electrode 26 and the movable electrode 27, an error factor caused by a change in temperature can be removed.

Here, the capacitance type pressure sensor according to the present invention is not limited to the above-described embodiment, and various modifications and changes are possible. For example, the holding member 22 is formed integrally with the substrate 21 using the same material. Alternatively, the movable plate 25 may be formed of another material such as sapphire.

As shown by a two-dot chain line in FIG.
By forming a step portion 54 constituting an overload prevention portion on the inner surface of the movable plate 1 and supporting the lower surface of the movable plate 25 with the step portion 54, the strain-generating portion 23A of the diaphragm 23 when an excessive pressure is applied is formed. Plastic deformation, breakage, etc. may be prevented.

Next, a method of manufacturing the sensor element in the capacitance type pressure sensor according to the present invention will be described. 7 to 15 are views for explaining a process of forming the sensor element S and the capacitance type pressure sensor 20 shown in FIGS. This capacitance type pressure sensor 20 is manufactured in the same manner as a semiconductor chip in a large number of, for example, a 4-inch square sapphire substrate having a thickness of about 0.5 mm, and then separated into individual sensors by dicing. There is
A procedure for manufacturing one of the sensors will be described. In addition, the present manufacturing method uses the above-described reference electrodes 36, 3
A method of manufacturing a pressure sensor not including the pressure sensor 9 will be described.

FIGS. 7A and 7B show the cover plate 24.
In a plan view and a cross-sectional view for explaining a forming step, a pressure introducing hole 44 is formed at the center of a plate material 55 made of a sapphire substrate by laser processing so as to penetrate the front and back surfaces. Next, the front and back surfaces of the sapphire substrate are finished to a mirror surface that can be directly bonded by polishing. Next, the cover plate 24 is manufactured by forming a recess 46 having a required depth in the center of the back surface by dry etching.

Either of the pressure introducing holes 44 and the concave portions 46 may be formed first. Peripheral edge 46 of recess 46
a defines the outer peripheral edge of the strain generating portion 23A of the diaphragm 23. The surface of the plate material 55, that is, the surface opposite to the back surface on which the concave portion 46 is formed is formed as a flat surface, but the concave portion 45 shown in FIG. 1 may be formed. .

FIGS. 8A and 8B are a plan view and a cross-sectional view for explaining the joining process of the diaphragm 23 and the cover plate 24. FIG. The diaphragm 23 is formed into a very thin plate having a constant thickness by polishing a sapphire substrate, and the front and back surfaces are mirror-finished. The diaphragm 23 is placed on the back surface of the cover plate 24 where the concave portion 46 is formed, and the outer peripheral edge of the diaphragm 23 is directly bonded to cover the concave portion 46. When the diaphragm 23 is joined to the cover plate 24, a central portion of the diaphragm 23 corresponding to the concave portion 46 becomes a strain generating portion 23A, and an outer portion therefrom becomes a fixing portion 23B.

FIGS. 9A and 9B are a plan view and a cross-sectional view for explaining a step of forming a fixed electrode. A conductive thin film is formed on the entire surface of the diaphragm 23 opposite to the cover plate 24 side. The fixed electrode 26 having a predetermined shape is formed by forming a film and patterning it by an engraving technique. The conductive thin film can be formed by a dry film forming method, such as CVD, vacuum deposition, or sputtering, which is usually used in a semiconductor process. At this time, needless to say, the wiring section 40 and the pad section 41 shown in FIG. 4 are simultaneously formed.

FIGS. 10 to 13 (a) and 13 (b) are a plan view and a sectional view for explaining a step of forming the holding member and the movable plate, and FIGS. 14 (a), (b) and (c) are holding views. FIG. 4 is a plan view for explaining a step of forming a member and a movable plate, FIG.
It is the sectional view on the A line and the BB sectional view. First, in FIG. 10, a movable plate material 60 made of a sapphire substrate having a predetermined plate thickness is prepared. Movable plate material 60
Has a polished front and back surface, and an annular (square) separating groove 61 is formed near the outer periphery of the surface (joining surface with the diaphragm) by ultrasonic processing or the like. This separating groove 6
1 is formed sufficiently deeper than the thickness of the movable plate 25.

An electrode hole 35 composed of two through holes is formed outside the separation groove 61 by laser processing or the like. The two electrode holes 35 are formed at positions corresponding to the pad portions 41 of the fixed electrode 26, and pass through the center of the movable plate material 60 and are imaginary lines 62 perpendicular to two sides facing each other. Located on top. Further, an annular groove 63 is formed by removing a predetermined amount of the outer surface of the surface from the separation groove 61 by dry etching over the entire circumference. Separation groove 61, electrode hole 35
The order of forming the grooves 63 is not particularly limited. The outer portion and the inner portion of the separation groove 61 are portions that will eventually become the holding member 22 and the movable plate 25. The reason for forming the groove 63 is that a groove 64 for setting an electrode interval to be described later is used.
Is formed so that the connecting portion 25B protrudes from the upper surface of the outer peripheral edge serving as the holding member 22.

FIGS. 11A and 11B are a plan view and a cross-sectional view for explaining a step of forming a groove for setting an electrode interval. A portion of the surface of the movable plate material 60 inside the separation groove 61 and excluding the center is removed by a predetermined amount by dry etching to form an electrode gap setting groove 64. As a result, the portion where the electrode interval setting groove 64 is formed is a portion that becomes the electrode forming portion 25A of the movable plate 25, and the groove bottom surface is the electrode forming surface 47. The protrusion remaining at the center of the surface of the movable plate material 60 due to the formation of the electrode gap setting groove 64 is a portion serving as a connection portion 25 </ b> B with the diaphragm 23. Since the distance from the bottom surface to the upper surface of the connection portion 25B defines the inter-electrode distance, the electrode gap setting groove 64 is formed with high accuracy. Further, the upper surface of the connection portion 25B slightly protrudes above the outer peripheral portion of the movable plate material 60, that is, the upper surface outside the portion where the electrode gap setting groove 64 is formed. 49 (FIG. 2) are formed. The protruding dimension Δd is provided to ensure the direct connection between the connection portion 25B and the diaphragm 23 (this point will be described later).

Further, a concave portion 65 is formed by removing a predetermined amount of a surface portion outside the separation groove 61 and a portion corresponding to the electrode hole 35 by dry etching.
The recess 65 communicates with the separation groove 61, but does not open to the outer surface of the movable plate material 60. The recess 65 is formed to be lower than the electrode spacing groove 64. In FIG. 11, the electrode interval setting groove 64 and the concave portion 65 are shown in black. At this time, a hole 48 (FIG. 2) for reducing the weight is also formed.
Its illustration is omitted.

FIGS. 12A and 12B are a plan view and a cross-sectional view for explaining a step of forming a movable electrode. A conductive thin film is formed on the surface of the movable plate material 60 inside the separation groove 61, and is patterned by an engraving technique to form the movable electrode 27 having a predetermined shape. Similar to the formation of the fixed electrode 26, this conductive thin film is formed by CV, which is a dry film formation usually used in a semiconductor process.
D, a vacuum deposition, a sputtering method, or the like.

FIGS. 13 (a) and 13 (b) are a plan view and a sectional view for explaining the joining process of the diaphragm and the movable plate material 60. The back surface is turned upside down by turning the diaphragm 23 upside down. Further, the movable plate material 60 manufactured in the above process is also turned upside down and positioned and placed on the diaphragm 23. Thereby, the outer peripheral edge of the movable plate material 60 contacts the outer peripheral edge of the back surface of the diaphragm 23, and the connecting surface 49 of the connecting portion 25B contacts the center of the rear surface of the diaphragm 23 and is directly joined. At this time, the outer peripheral edge of the movable plate material 60 and the connecting portion 25
B connecting surface 49 is the same surface, that is, the protrusion dimension Δd
When (FIG. 11) is zero, when the connecting portion 25B comes into contact with the diaphragm 23, the strain generating portion 23A of the diaphragm 23
May be elastically deformed downward, so that good joining may not be obtained. However, if the protrusion is made only by Δd, the connecting portion 25B presses the strain generating portion 23A by this amount of projection Δd to elastically deform downward. As a result, reliable direct bonding can be obtained.

FIGS. 14A, 14B, and 14C are a plan view, a sectional view taken along the line AA, and a sectional view taken along the line BB for explaining the process of forming the holding member 22 and the movable plate 25. . After the movable plate material 60 is directly bonded to the back surface of the diaphragm 23 in the above process, the entire back surface on the movable plate material 60 is removed by a predetermined amount by dry etching, so that the closed end of the separation groove 61 is removed. Open upward. Thus, the outer and inner portions are completely separated from the separating groove 61, the outer portion becomes the holding member 22, and the inner portion becomes the movable plate 25, whereby the sensor element S is manufactured.

FIG. 15 is a cross-sectional view for explaining a joining process of the substrate 21 and the holding member 22. The holding member formed in the above-described process is formed on the substrate 21 in which the concave portion 30 and the pin insertion hole 33 are formed. 22 are placed and integrally joined by brazing or the like. Further, the electrode extraction pin 28 is inserted into the electrode hole 35 from the pin insertion hole 33, and the inserted end thereof is fixed to the fixed electrode 26.
Contact with the pad portion 41 of Furthermore, the pin insertion hole 33
The molten solder is poured into the electrode holes 35 to electrically connect the electrode extraction pins 28 to the pad portions 41 of the fixed electrodes 26. Then, the molten solder is solidified in the pin insertion hole 33 and the electrode hole 35 to hermetically seal these holes.

Thereafter, the vacuum evacuation pipe 32 is connected to a vacuum pump (not shown), and the vacuum pump evacuates the air in the enclosed space surrounded by the substrate 21, the holding member 22, and the diaphragm 23, thereby obtaining a predetermined gas. The vacuum chamber 31 has a vacuum degree. Then, by sealing the vacuum exhaust pipe 32, the production of the capacitance type pressure sensor is completed.

In the capacitance type pressure sensor manufactured as described above, a large number of sensor elements S can be manufactured simultaneously in a substrate made of sapphire as in the case of the semiconductor process. Mass production of the element S is possible. This leads to cost reduction.

FIGS. 16A to 16F are views for explaining another manufacturing method for forming the holding member and the movable plate. The movable plate material 60 'used to form the holding member 22 and the movable plate 25 is the same as that shown in FIG.
As shown in (a) and (b), it is formed of the first and second plate materials 70 and 71. First plate material 7
0 consists of a sapphire substrate mirror-finished on both sides,
An annular (square) first separating groove 72 having a required depth is formed by ultrasonic processing on the joint surface with the second plate material 71 (a). The second plate material 71 is also made of a mirror-finished sapphire substrate that can be directly joined on both sides, and has an annular (square) second separating groove having a required depth on the joint surface with the first sapphire substrate 70. 73
Then, shallow communication grooves 74 are formed (b) and (c).

The first plate material 70 on which the first separation groove 72 is formed and the second plate material 71 on which the second separation groove 73 and the communication groove 74 are formed are directly joined at their joint surfaces. Thereby, the movable plate material 60 'is formed (d). Next, dry etching is performed on the entire upper surface of the plate material 71. Thereafter, two electrode holes 35 formed of through holes are formed in the movable plate material 60 'by laser processing (e). Further, by removing a predetermined amount of the surface of the first plate material 70 except for the central portion and the outer peripheral portion by dry etching, the electrode gap setting groove 64 is removed.
Is formed, and the protruding unetched portion remaining at the center is used as a connection portion 25B with the diaphragm 23 (f). Subsequent steps are exactly the same as the steps shown in FIGS.

Thus, the first and second plate materials 7
0 and 71 are directly joined to form one movable plate material 60 '.
Is formed, a fixed electrode 2 is formed in a step of separating the holding member 22 and the movable plate 25 by dry etching shown in FIG.
6 can be prevented from being etched, and disconnection of the fixed electrode 26 can be prevented. That is, the surface of the second plate material 71 is removed by a predetermined amount by dry etching, and the closed end of the separation groove 73 is opened, so that the portion outside the first and second separation grooves 72 and 73 is held by the holding member 2.
When the first and second separation grooves 72 and 73 are continuous straight grooves, the fixed electrode 26 may be over-etched. When the connecting portion is formed as a bent portion by the communication groove 74 by making the size of the second separating groove 73 different from that of the second separating groove 73, the portion A to be over-etched is the joining surface of the first and second plate materials 70 and 71. And only the portion corresponding to the second separating groove 73, the fixed electrode 26
Is not etched.

FIGS. 18 to 21 are views for explaining another method of forming electrodes. In this electrode forming method, an electrode is formed by a conductive material 80 such as solder and the pin 28 for taking out an electrode. FIGS. 18A and 18B are a plan view and a cross-sectional view for explaining a step of forming the conductive material 80 made of solder. The movable plate material 60 formed by the step shown in FIG. After being placed and directly joined, a molten solder material such as Sn-Ag or Pb-Sn is poured into the electrode hole 35 from above the movable plate material 60 and solidified to form the conductive material 80, and the fixed electrode 26 is electrically connected. Connection.

FIGS. 19 (a), (b) and (c) are a plan view, a cross-sectional view taken along the line AA and a cross-sectional view taken along the line BB for explaining the steps of forming the holding member 22 and the movable plate 25. is there.
After the formation of the conductive material 80, the closed end of the separation groove 61 is opened upward by removing a predetermined amount of the entire back surface on the movable plate material 60 by dry etching. As a result, the outer portion and the inner portion are completely separated from the separating groove 61, and the outer portion is held by the holding member 2
2, and the inner part is a movable plate 25. Conductive material 8
It is desirable that the pad portion of the fixed electrode 26 to which 0 is connected be formed of a material having low wettability so that the molten solder material does not flow out and come into contact with the diaphragm 23.

FIGS. 20A and 20B are a plan view and a cross-sectional view for explaining a step of forming the bump 81 on the conductive material 80 protruding from the surface of the holding member 22.
The bump 81 is formed in a portion exposed to the outside. Thereafter, as shown in FIG. 21, the holding member 22 is placed on the substrate 21 and joined by brazing or the like, and the electrode extraction pin 28 is inserted into the pin insertion hole 33 so that the inner end of the conductive material 80 is It is bonded to the bump 81. At the time of joining, a molten solder material such as Sn-Ag, Pb-Sn or the like is poured into the pin insertion hole 33 and solidified, so that the connection with the bump 81 is ensured and the pin insertion hole 33 is hermetically sealed.

FIGS. 22 to 32 are views for explaining a method of manufacturing a sensor element and a pressure sensor having a structure in which a holding member is not provided around the movable plate 25. FIG. The steps shown in FIGS. 22, 23 and 24 are exactly the same as the steps shown in FIGS. 7 to 9 described above. That is, FIG.
(B) is a plan view and a cross-sectional view for explaining the process of forming the cover plate 24. The front and back surfaces of the plate material 55 made of a sapphire substrate are mirror-finished, and the center of the back surface is recessed to a required depth by dry etching. A part 46 is formed. Furthermore, the cover plate 24 is manufactured by forming a pressure introduction hole 44 at the center so as to penetrate the front and back surfaces by laser processing.

FIGS. 23 (a) and 23 (b) show the diaphragm 23.
FIGS. 7A and 7B are a plan view and a cross-sectional view for explaining a joining process of the cover plate 24 and the fixing portion 23B of the diaphragm 23 on the back surface where the concave portion 46 of the cover plate 24 is formed.
Are placed and joined directly to cover the recess 46.
The diaphragm 23 is made of a sapphire substrate having a required thickness and a predetermined size and a constant thickness, and the front and back surfaces are mirror-finished. Cover the diaphragm 23 with the cover plate 2
4, the concave portion 4 of the diaphragm 23
The central portion corresponding to No. 6 is the strain generating portion 23A.

FIGS. 24 (a) and 24 (b) are a plan view and a sectional view for explaining a step of forming the fixed electrode 26. A conductive thin film is formed on the entire surface of the diaphragm 23 opposite to the cover plate 24 side. By forming a film and patterning it by the engraving technique, the fixed electrode 26 having a predetermined shape is formed on the fixed part 23B by the same technique as described above.

FIGS. 25A and 25B are a plan view and a sectional view showing a step of covering the wiring portion of the fixed electrode 26 with the protective film. ) To form a protective film 90 by solidifying it by dropping it.

FIGS. 26A and 26B are a plan view and a cross-sectional view showing a step of forming a gold bump 91 on the pad portion 41 of the fixed electrode 26. Melted gold is dropped on the pad portion 41. Then, the bumps 91 are formed.

FIGS. 27 to 29 are views for explaining the steps of forming the movable plate 25. FIG. FIGS. 27A and 27B
A groove 93 is prepared by preparing a movable plate material 92 made of a sapphire substrate having a predetermined thickness, and removing the outer peripheral portion of the movable plate material 92 by a predetermined depth over the entire circumference.
FIGS. 4A and 4B are a plan view and a cross-sectional view illustrating a step of forming a semiconductor device. Thus, the flange 95 is formed on the lower end side of the outer peripheral surface of the movable plate material 92.

FIGS. 28 (a) and 28 (b) are a plan view and a cross-sectional view showing a step of forming an electrode gap setting groove 64 by dry etching on the surface of the movable plate material 92 except for the center. The unetched portion remaining at the center is used as a connection portion 25B with the diaphragm.

FIGS. 29A and 29B are a plan view and a cross-sectional view for explaining the step of forming the movable electrode 27. FIG. A movable electrode 27 having a predetermined shape is formed by forming a conductive thin film on the outer peripheral portion of the bottom surface of the electrode interval setting groove 64 and patterning the thin film by an engraving technique.

FIGS. 30A and 30B show the state of the diaphragm 23.
FIGS. 9A and 9B are a plan view and a cross-sectional view for explaining a joining step between the movable plate material 92 and the movable plate material 92. FIGS. By turning the diaphragm 23 upside down, the back side is turned up. In addition, the movable plate material 92 manufactured in the above process is also turned upside down and positioned and placed on the diaphragm 23. As a result, the connection portion 25B is directly joined to the back surface of the strain generating portion of the diaphragm 23.

FIGS. 31A and 31B show the movable plate 25.
FIGS. 4A and 4B are a plan view and a cross-sectional view for explaining a forming step of FIG. The surface on the movable plate material 92 is removed by a predetermined amount by dry etching, and the flange is completely removed. Thereby, the movable plate 25 is formed, and the sensor element 96 is formed. The sensor element 96 includes the diaphragm 23, the cover plate 24, and the movable plate 2.
5.

FIG. 32 is a sectional view for explaining a sealing step of the sensor element 96. One end of the electrode extraction pin 28 is connected to the gold bump 91 by soldering or the like. The electrode extraction pin 28 is attached so as to be parallel to the diaphragm 23 and extends to the side of the sensor element 96. Next, an opening 1 is formed at the center of the upper surface formed of glass, metal, or the like.
The sensor element 96 is incorporated into an upper case (holding member) 100 having the cover 101, the opening 101 is closed by the cover plate 24, and joined by brazing or the like. Further, the upper case 100 is placed on the upper surface of the lower case (substrate) 103 made of glass, metal, or the like, and the joint between the two cases is sealed. Thereafter, the inside of the case is evacuated to a vacuum chamber 105 having a predetermined degree of vacuum, thereby completing the production of the capacitance type pressure sensor 106.

In such a manufacturing method, since the upper case 100 is used in place of the holding member 22 shown in FIG. 2, the connection and extraction of the electrode extraction pin 28 to and from the fixed electrode 26 are relatively easy. is there.

In the above embodiment, the case where the shape of the pressure sensor is a square has been described. However, the present invention is not limited to this, and various shapes such as a polygon, a circle, and an ellipse may be used. The same effect can be obtained even if the shape is as described above.

[0084]

As described above, the sensor element according to the present invention includes the diaphragm that forms a part of the vacuum chamber,
In the sensor element of the capacitive pressure sensor that detects the elastic deformation of the strain-generating portion of the diaphragm as a change in capacitance, the central portion forms a strain-generating portion, and the portion outside the strain-generating portion forms a fixed portion. A diaphragm having a pressure introducing hole, a cover plate forming a pressure introducing chamber together with the diaphragm by joining the fixed part of the diaphragm, an electrode forming part and a center of an electrode forming surface of the electrode forming part. A movable plate having a connection portion integrally projecting therefrom, and joining the connection portion of the movable plate to a surface opposite to the cover plate side at the center of the strain generating portion of the diaphragm, and fixing the diaphragm with a fixed portion. Since the fixed electrode and the movable electrode are formed so as to face each other in the electrode forming portion of the movable plate, when the atmospheric pressure is applied to the strain generating portion of the diaphragm, the strain generating portion is moved. For enlarging the elastic deformation to the inter-electrode distance Check side, without the electrodes each other are in close contact,
It is easy to handle during manufacture and shipping, and does not become unusable. Further, since the deformation direction of the strain generating portion is a direction in which the inter-electrode distance increases, the strain generating portion can be deformed to the maximum within the elastic deformation limit, and the pressure range can be widened. Furthermore, since the fixed electrode is provided on the fixed part of the diaphragm and not on the strain-generating part with large elastic deformation, even if the strain-generating part expands and contracts due to temperature change, the influence is small, and high measurement accuracy and reliability It is possible to provide a sensor element and a capacitance type pressure sensor which are excellent in quality.

Further, since sapphire or quartz is used as the material of the sensor element, it is excellent in corrosion resistance, and since it is directly joined, a highly accurate distance between the electrodes can be obtained. In addition, since the movable plate is provided with a through hole or a non-through hole for reducing the weight, its own mass is hardly affected by gravity or acceleration, and the limitation on the vibration characteristics and the attitude of the sensor is eliminated.

Further, since the overload preventing portion is provided, it is possible to prevent breakage of the strain generating portion of the diaphragm due to excessive pressure.

Further, according to the method of manufacturing a sensor element according to the present invention, a sensor element having a movable plate in a strain-causing portion of a diaphragm can be manufactured, and a manufacturing method in which a separating groove is formed by a bent groove. In the method, there is no fear that the fixed electrode is etched and cut during the dry etching, and the sensor element can be manufactured favorably.

Further, according to the method of manufacturing a sensor element according to the present invention, it is possible to mass produce the same quality as in the case of semiconductor manufacturing.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG. 1;

FIG. 4 is a plan view of a fixed electrode.

FIG. 5 is a plan view of a movable electrode.

FIG. 6 is a diagram showing a state in which a strain generating portion of a diaphragm is deformed toward the vacuum chamber due to atmospheric pressure during manufacturing and shipping.

FIGS. 7A and 7B are a plan view and a cross-sectional view illustrating a step of forming a cover plate.

FIGS. 8A and 8B are a plan view and a cross-sectional view for explaining a joining step of a diaphragm and a cover plate.

FIGS. 9A and 9B are a plan view and a cross-sectional view for explaining a step of forming a fixed electrode.

FIGS. 10A and 10B are a plan view and a cross-sectional view illustrating a step of forming a holding member and a movable plate.

FIGS. 11A and 11B are a plan view and a cross-sectional view illustrating a step of forming a holding member and a movable plate.

12A and 12B are a plan view and a cross-sectional view for explaining a step of forming a holding member and a movable plate.

FIGS. 13A and 13B are a plan view and a cross-sectional view illustrating a step of forming a holding member and a movable plate.

FIGS. 14A, 14B, and 14C are a plan view, an AA cross-sectional view, and a BB cross-sectional view illustrating a process of forming a holding member and a movable plate.

FIG. 15 is a view for explaining a bonding step between the substrate and the holding member.

FIGS. 16A to 16F are cross-sectional views illustrating another manufacturing method for forming the holding member and the movable plate.

FIG. 17 is a cross-sectional view illustrating a step of separating the holding member and the movable plate.

18A and 18B are a plan view and a cross-sectional view for explaining another method for forming an electrode.

FIGS. 19A and 19B are a plan view, an AA cross-sectional view, and a BB cross-sectional view for explaining a forming process of the holding member and the movable plate.

FIGS. 20A and 20B are a plan view and a cross-sectional view illustrating a step of forming a bump on a conductive material protruding from the surface of a holding member.

FIG. 21 is a cross-sectional view illustrating a step of forming an electrode.

22A and 22B are a plan view and a cross-sectional view for explaining a method for manufacturing a sensor element and a pressure sensor having a structure in which a holding member is not provided around a movable plate.

FIGS. 23 (a) and 23 (b) are a plan view and a cross-sectional view for explaining a joining step of a diaphragm and a cover plate.

FIGS. 24A and 24B are a plan view and a cross-sectional view for explaining a step of forming a fixed electrode.

FIGS. 25A and 25B are a plan view and a cross-sectional view for explaining a step of covering a wiring portion of a fixed electrode with a protective film.

26A and 26B are a plan view and a cross-sectional view for explaining a step of forming a gold bump on a pad portion of a fixed electrode.

FIGS. 27A and 27B are a plan view and a cross-sectional view illustrating a step of forming a movable plate.

FIGS. 28A and 28B are a plan view and a cross-sectional view for explaining a step of forming an electrode gap setting groove in a movable plate.

29 (a) and (b) are a plan view and a cross-sectional view for explaining a step of forming a movable electrode.

FIGS. 30A and 30B are a plan view and a cross-sectional view for explaining a joining step of a diaphragm and a movable plate material.

FIGS. 31 (a) and (b) are a plan view and a cross-sectional view illustrating a step of forming a movable plate.

FIG. 32 is a cross-sectional view for explaining a sealing step of the sensor element.

FIG. 33 is a sectional view of a conventional capacitance type pressure sensor.

[Explanation of symbols]

20: Capacitance pressure sensor, 21: Substrate, 22: Holding member, 23: Diaphragm, 23A: Strain-flexing part, 23B ...
Fixed part, 24 ... cover plate, 25 ... movable plate,
25A: electrode forming portion, 25B: connecting portion, 26: fixed electrode, 27: movable electrode, 28: electrode extracting pin, 31: vacuum chamber, 44: pressure introducing hole, 46: concave portion, 47: electrode forming surface, Reference numeral 48 denotes a hole for reducing the weight, 49 denotes a connection surface, 51 denotes a pressure introduction chamber, 54 denotes an overload prevention part, 55 denotes a plate material, 6
0: movable plate material, 61: separation groove, 64: electrode interval setting groove.

Claims (11)

[Claims] 1. A sensor element of a capacitive pressure sensor for detecting an elastic deformation of a strain-generating portion of the diaphragm as a change in capacitance, the diaphragm including a diaphragm constituting a part of a vacuum chamber, wherein a central portion has a strain-generating portion. A cover having a pressure-introducing hole, and a pressure-introducing chamber formed with the diaphragm by joining the fixed portion of the diaphragm. A movable plate having an electrode forming portion and a connecting portion integrally projecting from the center of the electrode forming surface of the electrode forming portion, and a surface opposite to the cover plate at the center of the strain generating portion of the diaphragm. To the joint of the movable plate,
A sensor element for a capacitive pressure sensor, wherein a fixed electrode and a movable electrode are formed on a fixed portion of the diaphragm and an electrode forming portion of the movable plate so as to face each other. 2. The sensor element of the capacitance type pressure sensor according to claim 1, wherein the diaphragm, the cover plate, and the movable plate are formed of the same material, respectively, and are integrally joined by direct joining. Sensor element of a capacitive pressure sensor. 3. A capacitance type pressure sensor comprising a diaphragm constituting a part of a vacuum chamber, and detecting an elastic deformation of a strain generating portion of the diaphragm as a change in capacitance. A cover plate that forms a pressure introduction chamber together with the diaphragm by covering a pressure receiving surface of the diaphragm; and a frame-shaped holding portion that sandwiches an outer peripheral edge of the diaphragm together with the cover plate, and the vacuum chamber together with the diaphragm. A substrate to be formed, an electrode forming portion, and a connecting portion integrally projectingly provided at the center of the electrode forming surface of the electrode forming portion. The connecting portion is provided at the center of the strain generating portion on the surface of the diaphragm on the vacuum chamber side. A movable plate joined to the diaphragm, the diaphragm, the cover plate, and the movable plate constitute a sensor element; Capacitive pressure sensor, characterized in that provided so as to face each other with the fixed electrode and the movable electrode on the electrode formation surface of the outer peripheral edge portion of the ram movable plate. 4. The capacitance type pressure sensor according to claim 3, wherein a hole for reducing the weight is provided in the electrode forming portion of the movable plate. 5. The capacitance type pressure sensor according to claim 3, wherein an overload prevention portion for restricting displacement of the movable plate is provided on the substrate. 6. The capacitance type pressure sensor according to claim 3, wherein the cover plate has a recess for a pressure introduction chamber, and the diaphragm is formed in a thin plate shape having a constant thickness. The outer peripheral edge forms a fixed portion by being joined to the cover plate, and a portion inside the fixed portion forms a strain generating portion, and a fixed electrode is formed on a surface of the fixed portion on the vacuum chamber side. A capacitance-type pressure sensor characterized in that: 7. The capacitance type pressure sensor according to claim 3, wherein the diaphragm, the cover plate and the movable plate are respectively formed of the same material, and these are integrally joined by direct joining. A capacitance type pressure sensor, wherein a sensor element is constituted by: 8. The capacitance type pressure sensor according to claim 7, wherein the diaphragm, the cover plate and the movable plate are formed of sapphire or quartz. 9. A method for manufacturing a sensor element in a capacitance type pressure sensor which includes a diaphragm constituting a part of a vacuum chamber and detects elastic deformation of a strain-generating portion of the diaphragm as a change in capacitance. Forming a cover plate having a pressure introducing hole by a plate material; and joining the cover plate formed in the step and the outer peripheral edge of the diaphragm integrally with the outside of the diaphragm. A step of forming a peripheral portion as a fixed portion, a portion inside the fixed portion as a strain-flexing portion, and a step of forming a fixed electrode on an outer peripheral edge of a surface opposite to the cover plate side in the fixed portion of the diaphragm; The electrode forming part is formed by removing the part of the movable plate material other than the central part by etching. Forming a connection portion joined to the diaphragm by an unetched portion; forming a movable plate by forming a movable electrode on an electrode forming surface of the electrode forming portion of the movable plate material; Joining the connecting portion to the center of the strain-generating portion of the diaphragm. 10. A method for manufacturing a sensor element in a capacitance type pressure sensor which includes a diaphragm constituting a part of a vacuum chamber and detects elastic deformation of a strain-generating portion of the diaphragm as a change in capacitance. Forming a diaphragm having a constant thickness by the step of: forming a cover plate having a pressure introducing hole and a concave portion for a pressure introducing chamber by using a plate material; and forming a cover plate formed by the step and an outside of the diaphragm. A step of integrally joining a peripheral edge portion to form an outer peripheral edge portion of the diaphragm as a fixed portion, and forming an inner portion from the fixed portion as a strain-flexing portion; and a fixing portion of the diaphragm opposite to the cover plate side. Forming a fixed electrode on the outer peripheral edge of the surface; and one of the surfaces of the movable plate material being larger than the strain-causing portion of the diaphragm. Forming a groove for separation and a pin insertion hole located outside the separation groove; and removing an inner portion of the movable plate material inside the separation groove in an annular shape by dry etching. Forming a connection portion joined to the diaphragm by an unetched portion; forming a movable electrode on an electrode formation surface of the electrode formation portion of the movable plate material; Joining a portion of the plate material outside of the connecting groove and the separation groove to a strain-flexing portion and a fixed portion of the diaphragm; and dry-etching a surface of the movable plate material on a side opposite to the diaphragm side by a predetermined depth. Then, the movable plate material is separated into an outer portion and an inner portion of the separation groove by removing the closed end of the separation groove so as to maintain the substrate. Method for producing a sensor element characterized by comprising a step of forming a part and a movable plate, a. 11. The method for manufacturing a sensor element in a capacitance type pressure sensor according to claim 10, wherein the movable plate material includes a first plate material having an annular first separating groove formed on a joint surface; A second plate material, which is made of the same material as the first plate material, has an annular second separating groove formed on a joint surface with the first plate material, and is directly joined to the first plate material. Wherein the first or second plate material has a first surface
A method for manufacturing a sensor element, wherein a communication groove for connecting a separation groove and a second separation groove to each other is formed.