CN115144103A - Pressure sensor and method for manufacturing pressure sensor - Google Patents

Abstract

The invention discloses a pressure sensor and a preparation method of the pressure sensor. The pressure sensor comprises a sensor body, the sensor body has an air cavity with one end open, the bottom wall of the air cavity is provided with an exhaust hole, and the exhaust hole is arranged near the edge of the bottom wall ; Capacitor and vibrating membrane, the capacitor is set on the sensor body and has a deformation zone corresponding to the open end of the air cavity; the vibrating membrane is set on the side of the capacitor away from the sensor body, and the vibrating membrane acts on the deformation zone to change the capacitor when the vibrating membrane is under pressure. capacitance to detect pressure based on the capacitance of the capacitor. Therefore, through the cooperation of the sensor body, the capacitor and the vibrating membrane, when the vibrating membrane is bent towards the air cavity under pressure, the gas in the air cavity is discharged from the air cavity from the exhaust hole, and the gas in the air cavity will not produce resistance to the movement of the vibrating membrane , the vibrating membrane can reliably act on the deformation area to change the capacitance of the capacitor, so that the detection linearity and sensitivity of the pressure sensor can be improved.

Description

Pressure sensor and preparation method of pressure sensor

technical field

The invention relates to the field of pressure detection, in particular to a pressure sensor and a preparation method of the pressure sensor.

Background technique

In related technologies, pressure is an important detection indicator for the normal operation of the system. As one of the most commonly used MEMS sensors, pressure sensors have been developed for various applications that need to monitor absolute pressure or Differential pressure applications. Contact pressure sensors are resistant to overloading and have the advantage of being one to two orders of magnitude more sensitive than traditional non-contact sensors, which are increasingly being used due to their advantages over traditional non-contact sensors. more attention.

In the prior art, the pressure sensor is provided with an air cavity and a vibrating membrane, the open end of the air cavity is sealed, and the vibrating membrane covers the open end of the air cavity. A high-density gas compression area is formed between the inner walls, which creates resistance to the further downward movement of the vibrating membrane, which reduces the linearity and sensitivity of the pressure sensor.

SUMMARY OF THE INVENTION

The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, an object of the present invention is to provide a pressure sensor. When the vibrating membrane is bent towards the air cavity under pressure, the gas in the air cavity is discharged from the air cavity from the exhaust hole, and the gas in the air cavity will not affect the vibrating membrane. The movement creates resistance, which improves the detection linearity and sensitivity of the pressure sensor.

The present invention further provides a preparation method of the pressure sensor.

The pressure sensor according to the present invention includes:

a sensor body, the sensor body has an air cavity with one end open, the bottom wall of the air cavity is provided with an exhaust hole, and the exhaust hole is arranged close to the edge of the bottom wall;

a capacitor and a vibrating membrane, the capacitor is provided on the sensor body and has a deformation area corresponding to the open end of the air cavity;

The vibrating membrane is arranged on the side of the capacitor away from the sensor body. When the vibrating membrane is under pressure, the vibrating membrane acts on the deformation area to change the capacitance of the capacitor, so as to detect the capacitance according to the capacitance of the capacitor. pressure.

In some examples of the invention, the vent is tangent to the edge of the bottom wall.

In some examples of the present invention, the vent hole is a circular hole;

The diameter of the vent hole is R, which satisfies the relationship: 2 μm≤R≤10 μm.

In some examples of the present invention, there are a plurality of the exhaust holes, and the plurality of the exhaust holes are sequentially spaced apart along the circumference of the bottom wall.

In some examples of the present invention, the total volume of the vent holes is less than the volume of the air cavity.

In some examples of the present invention, the capacitor includes: a dielectric layer, a first metal electrode and a second metal electrode, the first metal electrode is provided on the surface of the sensor body close to the capacitor and is provided on the air On the inner wall surface of the cavity, the first metal electrode is provided with the dielectric layer on the side away from the sensor body, and the second metal electrode is provided on the side of the dielectric layer away from the first metal electrode and formed With the deformation zone, when the vibrating membrane is under pressure, the vibrating membrane acts on the second metal electrode so that the second metal electrode extends into the air cavity and the The dielectric layer contacts to change the capacitance of the capacitor.

In some examples of the present invention, the dielectric layer has a first avoidance hole, the first metal electrode has a second avoidance hole, and the first avoidance hole communicates with the exhaust hole through the second avoidance hole .

In some examples of the present invention, the dielectric layer is configured as a metal oxide layer.

In some examples of the present invention, the shape of the deformation zone is adapted to the cross-sectional shape of the air cavity.

According to the manufacturing method of the pressure sensor of the present invention, the pressure sensor comprises a sensor body, a capacitor and a vibrating membrane, the sensor body has an air cavity with one end open, the bottom wall of the air cavity is provided with an exhaust hole, and the capacitor It is arranged on the sensor body and has a deformation area corresponding to the open end of the air cavity. The vibrating membrane is arranged on the side of the capacitor away from the sensor body. The capacitor includes a dielectric layer and a first metal electrode. and a second metal electrode, the first metal electrode is arranged on the surface of the sensor body close to the capacitor and on the inner wall surface of the air cavity, and the first metal electrode is arranged on the side away from the sensor body With the dielectric layer, the preparation method includes the following steps:

Selecting a substrate base as the sensor body, and etching the air cavity on the sensor body;

Etch the exhaust hole on the bottom wall of the air cavity;

The first metal electrode is formed on the inner wall of the air cavity by magnetron sputtering;

The dielectric layer is formed on a surface of the first metal electrode away from the sensor body by atomic layer deposition;

The second metal electrode is formed on the surface of the vibrating film close to the capacitor by magnetron sputtering;

The second metal electrode is attached to the air cavity and bonded to the sensor body.

The beneficial effect of the present invention is that, according to the pressure sensor of the present invention, through the cooperation of the sensor body, the capacitor and the vibrating membrane, when the vibrating membrane is bent toward the air cavity under pressure, the gas in the air cavity is discharged from the exhaust hole to the air cavity, and the air cavity is The inner gas does not produce resistance to the movement of the vibrating membrane, and the vibrating membrane can reliably act on the deformation area to change the capacitance of the capacitor, thereby improving the detection linearity and sensitivity of the pressure sensor.

Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

1 is a cross-sectional view of a pressure sensor according to an embodiment of the present invention;

2 is a top view of a pressure sensor according to an embodiment of the present invention;

3 is a flow chart of a preparation method according to an embodiment of the present invention;

FIG. 4 is a comparison diagram of the variation trend of the capacitance of the existing pressure sensor and the pressure sensor of the present application.

Reference number:

pressure sensor 100;

Sensor body 10; Air cavity 11; Bottom wall 12; Exhaust hole 13;

capacitor 20; deformation region 21; dielectric layer 22; first metal electrode 23; second metal electrode 24; first avoidance hole 25; second avoidance hole 26;

Vibrating membrane 30 .

Detailed ways

The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, only used to explain the present invention, and should not be construed as a limitation of the present invention.

The pressure sensor 100 according to the embodiment of the present invention will be described below with reference to FIGS. 1 to 4 . The pressure sensor 100 is a capacitive pressure sensor 100 .

As shown in FIG. 1 , FIG. 2 , and FIG. 4 , the pressure sensor 100 according to the embodiment of the present invention includes a sensor body 10 , a capacitor 20 and a vibrating membrane 30 . The sensor body 10 has an air cavity 11 with one end open. When the pressure sensor 100 is placed in the direction shown in FIG. 1 , the upper end of the air cavity 11 is open, and the bottom wall 12 of the air cavity 11 is provided with an exhaust hole 13 , which penetrates the air. On the bottom wall 12 of the cavity 11 , the exhaust hole 13 communicates with the air cavity 11 and the atmospheric environment, and the exhaust hole 13 is arranged close to the edge of the bottom wall 12 . The capacitor 20 is disposed on the sensor body 10 , and the capacitor 20 has a deformation area 21 corresponding to the open end of the air cavity 11 . When the deformation area 21 is deformed, the capacitance of the capacitor 20 can be changed. The vibrating membrane 30 is disposed on the side of the capacitor 20 away from the sensor body 10 . The application takes the pressure sensor 100 placed in the direction shown in FIG. 1 as an example for description, and the vibrating membrane 30 is disposed on the upper side of the capacitor 20 . When the vibration film 30 is under pressure, the capacitance of the capacitor 20 is changed by the vibration film 30 acting on the deformation region 21 , so as to detect the pressure according to the capacitance of the capacitor 20 .

When the pressure sensor 100 detects the pressure, the vibrating membrane 30 is bent towards the air cavity 11 under the action of the pressure. When the vibrating membrane 30 is bent, the deformation area 21 is driven to deform to change the capacitance of the capacitor 20, and the pressure is detected by testing the capacitance change of the capacitor 20. , each capacitance value of the capacitor 20 corresponds to a pressure value. When the vibrating membrane 30 is subjected to different pressures, the vibrating membrane 30 has different bending degrees. When the vibrating membrane 30 with different bending degrees acts on the deformation area 21, the deformation and bending degree of the deformation area 21 of the capacitor 20 are different, so that the capacitor 20 has different capacitances. , under the action of different pressures, the capacitor 20 has different capacitances. When the vibrating membrane 30 is bent towards the air cavity 11 under the action of pressure, the gas in the air cavity 11 is discharged from the air cavity 11 from the exhaust hole 13, and the gas in the air cavity 11 will not produce resistance to the movement of the vibrating membrane 30, and the air cavity The gas in 11 has no limitation on the vibration and bending deflection of the vibrating membrane 30. When the vibrating membrane 30 is subjected to different pressures, it can ensure that the vibrating membrane 30 is smoothly bent toward the air cavity 11 and acts on the deformation zone 21, changing the capacitance of the capacitor 20. , so that the detection linearity and sensitivity of the pressure sensor 100 can be improved.

Therefore, through the cooperation of the sensor body 10 , the capacitor 20 and the vibrating membrane 30 , when the vibrating membrane 30 is bent toward the air cavity 11 under pressure, the gas in the air cavity 11 is discharged from the air cavity 11 through the exhaust hole 13 , and the gas in the air cavity 11 is discharged. There is no resistance to the movement of the vibrating membrane 30 , and the vibrating membrane 30 can reliably act on the deformation area 21 to change the capacitance of the capacitor 20 , thereby improving the detection linearity and sensitivity of the pressure sensor 100 .

In some embodiments of the present invention, as shown in FIG. 1 , the capacitor 20 may include: a dielectric layer 22 , a first metal electrode 23 and a second metal electrode 24 , and the first metal electrode 23 is provided on the sensor body 10 near the capacitor 20 . surface, and the first metal electrode 23 is arranged on the inner wall surface of the air cavity 11. It should be noted that the inner wall surface of the air cavity 11 includes the inner wall surface of the bottom wall 12 of the air cavity 11 and the inner wall surface of the side wall of the air cavity 11. The inner wall surface of the bottom wall 12 of 11 is provided with a first metal electrode 23, further, the inner wall surface of the side wall of the air cavity 11 can also be provided with a first metal electrode 23, and the end surface of the sensor body 10 close to the capacitor 20 can also be provided with a first metal electrode 23. The metal electrode 23 and the first metal electrode 23 are attached to the end of the sensor body 10 close to the capacitor 20 , the inner wall surface of the bottom wall 12 of the air cavity 11 and the inner wall surface of the side wall of the air cavity 11 . A dielectric layer 22 is provided on the side of the first metal electrode 23 away from the sensor body 10 , and the dielectric layer 22 is attached to the surface of the first metal electrode 23 away from the sensor body 10 . The second metal electrode 24 is disposed on the side of the dielectric layer 22 away from the first metal electrode 23 , and the second metal electrode 24 is formed with a deformation region 21 . As shown in FIG. 1 , the second metal electrode 24 is disposed on the upper end of the sensor body 10 . The second metal electrode 24 is extended in the radial direction of the sensor body 10 , the vibrating membrane 30 is arranged on the side of the second metal electrode 24 away from the sensor body 10 , and the vibrating membrane 30 can be attached to the second metal electrode 24 away from the sensor body 10 . surface. When the vibrating membrane 30 is under pressure, the vibrating membrane 30 acts on the second metal electrode 24 so that the second metal electrode 24 extends into the air cavity 11 and contacts the dielectric layer 22 disposed on the inner wall surface to change the capacitance of the capacitor 20 .

Specifically, when the pressure sensor 100 detects the pressure, the vibrating membrane 30 bends toward the air cavity 11 under the action of the pressure, the gas in the air cavity 11 is discharged from the air cavity 11 from the exhaust hole 13 , and the vibrating membrane 30 bends toward the air cavity 11 . When the deformation area 21 of the second metal electrode 24 is driven to bend toward the air cavity 11, the deformation area 21 of the second metal electrode 24 bends toward the air cavity 11 and then contacts the dielectric layer 22. The increase in the contact area between the electrode 24 and the dielectric layer 22 on the inner wall surface of the bottom wall 12 of the air cavity 11 causes the capacitance of the capacitor 20 to change, so that the pressure can be detected by testing the capacitance change of the capacitor 20. This setting can accurately detect the pressure, which can improve the The pressure sensor 100 detects sensitivity and linearity. In addition, since the air cavity 11 is connected to the atmospheric environment, the gas in the air cavity 11 has no limitation on the vibration and bending deflection of the vibrating membrane 30, which is conducive to better contact between the first metal electrode 23 and the second metal electrode 24, and further improves the pressure sensor. 100 detects linearity and sensitivity, enabling the pressure sensor 100 to perform high-accuracy pressure detection.

In some embodiments of the present invention, as shown in FIG. 1 , the dielectric layer 22 has a first avoidance hole 25 , the first metal electrode 23 has a second avoidance hole 26 , and the first avoidance hole 25 passes through the second avoidance hole 26 and the row The air holes 13 communicate with each other. Further, the dielectric layer 22 provided on the inner wall surface of the bottom wall 12 of the air cavity 11 is provided with a first avoidance hole 25 , and the first metal electrode 23 provided on the inner wall surface of the bottom wall 12 of the air cavity 11 is provided with a second avoidance hole 26 . . The first avoidance hole 25 communicates with the air cavity 11 and the second avoidance hole 26 , the second avoidance hole 26 communicates with the first avoidance hole 25 and the exhaust hole 13 , and the exhaust hole 13 communicates with the second avoidance hole 26 and the atmospheric environment. This arrangement can achieve the effect of communicating the air cavity 11 and the atmospheric environment, and can simplify the structure of the pressure sensor 100 .

In some embodiments of the present invention, the dielectric layer 22 may be configured as a metal oxide layer, for example, the metal oxide layer is made of oxides of metals such as silver, aluminum, and titanium. Further, the thickness of the dielectric layer 22 is 1 nm-1 μm. This arrangement can ensure the working performance of the dielectric layer 22 and the functionality of the capacitor 20 .

In some embodiments of the present invention, the first metal electrode 23 and the second metal electrode 24 are both metal materials with a thickness of 100 nm-1 μm and good electrical conductivity. Preferably, the metal electrode materials are silver, aluminum, titanium, gold, etc. Metal. This arrangement can ensure the working performance of the capacitor 20 and also the service life of the first metal electrode 23 and the second metal electrode 24 . The vibrating film 30 is an elastic film with a thickness of 1 μm-10 μm. Preferably, the material of the elastic film is polydimethylsiloxane, but the present invention is not limited to this, and the material of the elastic film can also be set to be the same as that of polydimethylsiloxane. Materials where oxanes play the same role, for example: silicon.

In some embodiments of the present invention, the exhaust hole 13 is tangent to the edge of the bottom wall 12 , it can also be understood that the exhaust hole 13 is tangent to the inner wall surface of the side wall of the air cavity 11 . It should be noted that, in the radial direction of the pressure sensor 100 , the position of the exhaust hole 13 opposite to the inner wall surface of the side wall of the air cavity 11 is tangent to the inner wall surface of the side wall of the air cavity 11 . Further, the exhaust hole 13 is provided as a circular hole. In this way, the exhaust hole 13 can be arranged at the edge of the bottom wall 12 of the air cavity 11, which can effectively avoid the formation of a high-density gas compression area between the vibrating membrane 30 and the inner side wall of the air cavity 11, and ensure that the gas in the air cavity 11 has a negative impact on the vibrating membrane 30. There is no limit to the vibration and bending deflection of the pressure sensor 100, which is more conducive to better contact between the first metal electrode 23 and the second metal electrode 24, and further improves the detection linearity and sensitivity of the pressure sensor 100.

In some embodiments of the present invention, the diameter of the exhaust hole 13 is R, which satisfies the relationship: 2μm≤R≤10μm, for example: the diameter of the exhaust hole 13 is 2μm, 4μm, 5μm, 10μm and other values, the exhaust hole The diameter size of 13 can be reasonably selected and arranged according to actual needs. When the vibrating membrane 30 is deformed by force, by setting 2 μm≤R≤10 μm, it can ensure that the gas in the air cavity 11 is discharged from the exhaust hole 13 in time, and it can ensure that the gas in the air cavity 11 has no limitation on the vibration bending deflection of the vibrating membrane 30 , which is more conducive to better contact between the first metal electrode 23 and the second metal electrode 24 , and further improves the detection linearity and sensitivity of the pressure sensor 100 , so that the diameter of the exhaust hole 13 is suitable.

In some embodiments of the present invention, a plurality of exhaust holes 13 may be provided, and the plurality of exhaust holes 13 are arranged at intervals along the circumferential direction of the bottom wall 12 . Further, the plurality of exhaust holes 13 are arranged along the bottom wall 12 . Circumferentially spaced uniformly in turn. The air cavity 11 is a cylindrical cavity, and further, the air cavity 11 is a cylindrical cavity. By arranging the plurality of exhaust holes 13 at intervals along the circumference of the bottom wall 12, when the vibrating membrane 30 is deformed by force, the The entire circumference of the air cavity 11 can ensure that the gas between the vibrating membrane 30 and the inner side wall of the air cavity 11 is discharged from the plurality of exhaust holes 13 in time to avoid excessive local pressure between the vibrating membrane 30 and the inner wall of the air cavity 11, preventing The situation occurs that the vibration bending deflection of the vibrating membrane 30 is restricted due to the untimely discharge of the gas.

In some embodiments of the present invention, the total volume of the vent holes 13 is less than the volume of the air cavity 11 . Wherein, if the air cavity 11 is not communicated with the atmospheric environment, the air cavity 11 is easily affected by the external temperature, and the temperature drift is relatively large. By making the total volume of the exhaust hole 13 smaller than the volume of the air cavity 11 , the temperature drift of the pressure sensor 100 can be reduced, and a sufficient capacitance value can be ensured after the first metal electrode 23 and the second metal electrode 24 are in contact.

In some embodiments of the present invention, the shape of the deformation region 21 is adapted to the cross-sectional shape of the air cavity 11 , and the cross-sectional shape of the deformation region 21 is the same as the cross-sectional shape of the air cavity 11 . Further, the transverse cross-sectional shape of the deformation region 21 The cross-sectional shape and the cross-sectional shape of the air cavity 11 are both circular. When the vibrating membrane 30 is deformed by force, the shape of the deformation area 21 is adapted to the cross-sectional shape of the air cavity 11 to ensure that the deformation area 21 smoothly faces the air cavity 11. The inner deformation and bending can ensure that the capacitance of the capacitor 20 is changed when the vibrating membrane 30 acts on the deformation area 21 , thereby ensuring the working reliability of the pressure sensor 100 .

It should be noted that, as shown in FIG. 1 , the second metal electrode 24 is located under the vibrating membrane 30 . When the pressure sensor 100 operates in the contact mode, the first metal electrode 23 and the second metal electrode 24 are separated by a layer of metal with a high dielectric constant. The oxide layer (ie, the dielectric layer 22 ) can have a higher capacitance value, which significantly improves the detection sensitivity of the pressure sensor 100 .

As shown in FIG. 4 , it is a comparison chart of the capacitance change trend of the existing pressure sensor and the pressure sensor 100 of the present application. The upper curve in FIG. 4 represents the relationship between the capacitance of the pressure sensor 100 of the present application and the pressure, and the lower curve in FIG. 4 represents the existing The capacitance of the pressure sensor varies with pressure. It can be seen from the figure that the linearity and sensitivity of the pressure sensor 100 of the present application are significantly improved.

In some embodiments of the present invention, the pressure sensor 100 may include a light-emitting portion, the light-emitting portion may be disposed on the sensor body 10, and the light-emitting portion may be configured as a light-emitting component such as a lamp. By providing the light-emitting portion, the pressure sensor 100 can be With a lighting function, it is convenient for the user to find the pressure sensor 100 in the case of insufficient lighting.

In some embodiments of the present invention, a filter screen is provided in the exhaust hole 13 , and the filter screen has a filtering function, which can prevent external particulate matter from entering the air cavity 11 and prevent particulate matter from accumulating in the air cavity 11 .

As shown in FIG. 3 , according to the manufacturing method of the pressure sensor 100 according to the embodiment of the present invention, the pressure sensor 100 is the pressure sensor 100 in the above-mentioned embodiment. The pressure sensor 100 includes a sensor body 10, a capacitor 20, and a vibrating membrane 30. The sensor body 10 has an air cavity 11 with one end open, and the bottom wall 12 of the air cavity 11 is provided with an exhaust hole 13. The capacitor 20 is provided on the sensor body 10 and has the same The open end of the air cavity 11 corresponds to the deformation area 21. The vibrating membrane 30 is provided on the side of the capacitor 20 away from the sensor body 10. The capacitor 20 includes a dielectric layer 22, a first metal electrode 23 and a second metal electrode 24. The first metal electrode 23 is arranged on the surface of the sensor body 10 close to the capacitor 20 and is arranged on the inner wall surface of the air cavity 11, the first metal electrode 23 is provided with a dielectric layer 22 on the side away from the sensor body 10, and the preparation method includes the following steps:

S10 , the substrate base is selected as the sensor body 10 , and the air cavity 11 is formed by etching on the sensor body 10 .

It should be noted that a silicon substrate is selected as the sensor body 10, a photoresist is spin-coated on the surface of the sensor body 10 and photolithography is performed to form a patterned mask layer, which is formed on the sensor body 10 by anisotropic dry etching. Air cavity 11 .

S20 , etching the exhaust hole 13 on the bottom wall 12 of the air cavity 11 .

It should be noted that the exhaust hole 13 is etched by anisotropic dry etching at the bottom wall 12 of the air cavity 11 near the edge.

S30, the first metal electrode 23 is formed on the inner wall surface of the air cavity 11 by magnetron sputtering.

It should be noted that, on the inner wall surface of the bottom wall 12 of the air cavity 11, the inner wall surface of the side wall of the air cavity 11, and the end surface of the sensor body 10 close to the capacitor 20, a metal film is grown by magnetron sputtering to form the first metal electrode 23. The first metal electrode 23 is provided on the sensor body 10 .

S40 , the medium layer 22 is generated by atomic layer deposition on the surface of the first metal electrode 23 on the side away from the sensor body 10 .

It should be noted that, a metal oxide corresponding to the material of the first metal electrode 23 is formed on the surface of the first metal electrode 23 away from the sensor body 10 by atomic layer deposition to form the dielectric layer 22 .

S50, the second metal electrode 24 is formed on the surface of the vibrating film 30 close to the capacitor 20 by magnetron sputtering.

It should be noted that the second metal electrode 24 is formed by magnetron sputtering metal thin film on the surface of the vibrating film 30 close to the capacitor 20 .

S60 , attaching the second metal electrode 24 to the air cavity 11 and bonding it to the sensor body 10 .

It should be noted that, as shown in FIG. 1 , the second metal electrode 24 is attached to the end of the sensor body 10 away from the capacitor 20 and covers the open end of the air cavity 11 , and the second metal electrode 24 is bonded to the sensor body 10 .

Wherein, the pressure sensor 100 that meets the requirements can be prepared by the above-mentioned preparation method of the pressure sensor 100 , the pressure detection sensitivity of the pressure sensor 100 can be improved, and the linearity of the pressure sensor 100 can also be improved.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples", etc., is meant to incorporate the embodiments A particular feature, structure, material, or characteristic described by an example or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, The scope of the invention is defined by the claims and their equivalents.

Claims (10)

1. a pressure sensor, is characterized in that, comprises: a sensor body, the sensor body has an air cavity with one end open, the bottom wall of the air cavity is provided with an exhaust hole, and the exhaust hole is arranged close to the edge of the bottom wall; a capacitor and a vibrating membrane, the capacitor is provided on the sensor body and has a deformation area corresponding to the open end of the air cavity; The vibrating membrane is arranged on the side of the capacitor away from the sensor body. When the vibrating membrane is under pressure, the vibrating membrane acts on the deformation area to change the capacitance of the capacitor, so as to detect the capacitance according to the capacitance of the capacitor. pressure. 2 . The pressure sensor of claim 1 , wherein the vent hole is tangent to the edge of the bottom wall. 3 . 3. The pressure sensor according to claim 1, wherein the exhaust hole is a circular hole; The diameter of the vent hole is R, which satisfies the relationship: 2 μm≤R≤10 μm. 4 . The pressure sensor according to claim 1 , wherein the exhaust holes are plural, and the plural exhaust holes are sequentially spaced along the circumference of the bottom wall. 5 . 5. The pressure sensor according to any one of claims 1-4, wherein the total volume of the exhaust hole is smaller than the volume of the air cavity. 6 . The pressure sensor according to claim 1 , wherein the capacitor comprises: a dielectric layer, a first metal electrode and a second metal electrode, and the first metal electrode is provided on the The sensor body is close to the surface of the capacitor and is provided on the inner wall of the air cavity, the first metal electrode is provided with the dielectric layer on the side away from the sensor body, and the second metal electrode is provided on the The side of the dielectric layer that is far away from the first metal electrode is formed with the deformation area. When the vibrating membrane is under pressure, the vibrating membrane acts on the second metal electrode so that the second metal electrode protrudes into the second metal electrode. The air cavity is in contact with the dielectric layer provided on the inner wall surface to change the capacitance of the capacitor. 7 . The pressure sensor according to claim 6 , wherein the dielectric layer has a first avoidance hole, the first metal electrode has a second avoidance hole, and the first avoidance hole passes through the second avoidance hole. 8 . A hole communicates with the exhaust hole. 8. The pressure sensor according to claim 6, wherein the dielectric layer is configured as a metal oxide layer. 9 . The pressure sensor of claim 1 , wherein the shape of the deformation zone is adapted to the cross-sectional shape of the air cavity. 10 . 10. A preparation method of a pressure sensor, wherein the pressure sensor comprises a sensor body, a capacitor and a vibrating membrane, the sensor body has an air cavity with one end open, and the bottom wall of the air cavity is provided with an exhaust hole , the capacitor is arranged on the sensor body and has a deformation area corresponding to the open end of the air cavity, the vibrating membrane is arranged on the side of the capacitor away from the sensor body, and the capacitor includes a dielectric layer, a first metal electrode and a second metal electrode, the first metal electrode is arranged on the surface of the sensor body close to the capacitor and on the inner wall surface of the air cavity, the first metal electrode is far away from the sensor body The dielectric layer is provided on one side of the device, and the preparation method includes the following steps: Selecting a substrate base as the sensor body, and etching the air cavity on the sensor body; Etch the exhaust hole on the bottom wall of the air cavity; The first metal electrode is formed on the inner wall of the air cavity by magnetron sputtering; The dielectric layer is formed on a surface of the first metal electrode away from the sensor body by atomic layer deposition; The second metal electrode is formed on the surface of the vibrating film close to the capacitor by magnetron sputtering; The second metal electrode is attached to the air cavity and bonded to the sensor body.

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