Pressure sensor and method for manufacturing a pressure sensor

Abstract

The present invention discloses a pressure sensor and a method for preparing the pressure sensor. The pressure sensor includes a sensor body, the sensor body having an air cavity open at one end, the bottom wall of the air cavity being provided with an exhaust hole, and the exhaust hole being arranged near the edge of the bottom wall; a capacitor and a vibrating membrane, the capacitor being provided in the sensor body and having a deformation zone corresponding to the open end of the air cavity; the vibrating membrane being provided on the side of the capacitor away from the sensor body, and when the vibrating membrane is subjected to pressure, the capacitance of the capacitor is changed by the vibrating membrane acting on the deformation zone, so as to detect pressure according to the capacitance of the capacitor. Thus, through the cooperation of the sensor body, the capacitor and the vibrating membrane, when the vibrating membrane is subjected to pressure and bends toward the air cavity, the gas in the air cavity is discharged from the air cavity through the exhaust hole, and the gas in the air cavity does not generate resistance to the movement of the vibrating membrane. The vibrating membrane can reliably act on the deformation zone to change the capacitance of the capacitor, thereby improving the detection linearity and sensitivity of the pressure sensor.

Description

Technical Field

[0001] The present invention relates to the field of pressure detection, and in particular to a pressure sensor and a method for preparing the pressure sensor. Background Art

[0002] In related technologies, pressure is a key indicator of system operation. As one of the most commonly used microelectromechanical system (MEMS) sensors, pressure sensors have been developed for various applications requiring absolute or differential pressure monitoring due to their high sensitivity, low-temperature sensitivity, and low power consumption. Contact pressure sensors offer strong overload resistance and are one to two orders of magnitude more sensitive than traditional non-contact sensors. Due to these advantages, contact sensors are gaining increasing attention.

[0003] 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. When the vibrating membrane is squeezed toward the air cavity, a high-density gas compression area is formed between the vibrating membrane and the inner wall of the air cavity, which produces resistance to further downward movement of the vibrating membrane, thereby reducing the linearity and sensitivity of the pressure sensor. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a pressure sensor in which, when a vibrating membrane is subjected to pressure and bends toward an air cavity, gas within the air cavity is discharged from the air cavity through an exhaust hole. The gas within the air cavity does not resist the movement of the vibrating membrane, thereby improving the detection linearity and sensitivity of the pressure sensor.

[0005] The present invention further proposes a method for preparing a pressure sensor.

[0006] The pressure sensor according to the present invention comprises:

[0007] A sensor body, the sensor body having an air cavity with one end open, a bottom wall of the air cavity being provided with an exhaust hole, and the exhaust hole being arranged near an edge of the bottom wall;

[0008] a capacitor and a vibrating membrane, wherein the capacitor is provided on the sensor body and has a deformation zone corresponding to the open end of the air cavity;

[0009] The vibration membrane is arranged on a side of the capacitor away from the sensor body. When the vibration membrane is under pressure, the capacitance of the capacitor is changed by the vibration membrane acting on the deformation zone, so as to detect pressure according to the capacitance of the capacitor.

[0010] In some examples of the present invention, the exhaust hole is tangent to the edge of the bottom wall.

[0011] In some examples of the present invention, the exhaust hole is a circular hole;

[0012] The diameter of the exhaust hole is R, which satisfies the relationship: 2μm≤R≤10μm.

[0013] In some examples of the present invention, there are a plurality of exhaust holes, and the plurality of exhaust holes are sequentially spaced apart along the circumference of the bottom wall.

[0014] In some examples of the present invention, a total volume of the exhaust holes is smaller than a volume of the air cavity.

[0015] 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 arranged on the surface of the sensor body close to the capacitor and on the inner wall surface of the air cavity, the dielectric layer is provided on the side of the first metal electrode away from the sensor body, the second metal electrode is provided on the side of the dielectric layer away from the first metal electrode and forms 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 contacts the dielectric layer provided on the inner wall surface, thereby changing the capacitance of the capacitor.

[0016] 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 is connected to the exhaust hole through the second avoidance hole.

[0017] In some examples of the present invention, the dielectric layer is configured as a metal oxide layer.

[0018] In some examples of the present invention, a shape of the deformation zone is adapted to a cross-sectional shape of the air cavity.

[0019] According to the method for preparing a pressure sensor of the present invention, the pressure sensor includes a sensor body, a capacitor, and a vibrating membrane. The sensor body has an air cavity open at one end, and the bottom wall of the air cavity is provided with an exhaust hole. The capacitor is provided in the sensor body and has a deformation zone corresponding to the open end of the air cavity. The vibrating membrane is provided on the side of the capacitor away from the sensor body. The capacitor includes a dielectric layer, a first metal electrode, and a second metal electrode. The first metal electrode is provided on a surface of the sensor body close to the capacitor and on an inner wall surface of the air cavity. The dielectric layer is provided on a side of the first metal electrode away from the sensor body. The preparation method includes the following steps:

[0020] Selecting a substrate base as the sensor body, and etching the air cavity on the sensor body;

[0021] Etching the exhaust hole on the bottom wall of the air cavity;

[0022] forming the first metal electrode on the inner wall surface of the air cavity by magnetron sputtering;

[0023] forming the dielectric layer on a surface of the first metal electrode away from the sensor body by atomic layer deposition;

[0024] forming the second metal electrode on the surface of the vibrating film close to the capacitor by magnetron sputtering;

[0025] The second metal electrode is attached to the air cavity and bonded to the sensor body.

[0026] 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 vibration membrane, when the vibration membrane is bent toward 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 generate resistance to the movement of the vibration membrane. The vibration membrane can reliably act on the deformation zone to change the capacitance of the capacitor, thereby improving the detection linearity and sensitivity of the pressure sensor.

[0027] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0029] Figure 1 is a cross-sectional view of a pressure sensor according to an embodiment of the present invention;

[0030] Figure 2 is a top view of a pressure sensor according to an embodiment of the present invention;

[0031] Figure 3 is a flow chart of a preparation method according to an embodiment of the present invention;

[0032] Figure 4 This is a comparison chart of capacitance change trends of the existing pressure sensor and the pressure sensor of the present application.

[0033] Reference numerals:

[0034] Pressure sensor 100;

[0035] Sensor body 10; air cavity 11; bottom wall 12; exhaust hole 13;

[0036] Capacitor 20; deformation zone 21; dielectric layer 22; first metal electrode 23; second metal electrode 24; first avoidance hole 25; second avoidance hole 26;

[0037] Vibrating membrane 30. DETAILED DESCRIPTION

[0038] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0039] Reference below Figure 1-Figure 4 The pressure sensor 100 according to an embodiment of the present invention is described. The pressure sensor 100 is a capacitive pressure sensor 100 .

[0040] like Figure 1 、 Figure 2 、 Figure 4 As shown in FIG. 1 , the pressure sensor 100 according to an embodiment of the present invention comprises: a sensor body 10, a capacitor 20 and a vibration membrane 30. The sensor body 10 has an air cavity 11 open at one end. Figure 1 When placed in the middle direction, 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. The exhaust hole 13 passes through the bottom wall 12 of the air cavity 11, and the exhaust hole 13 connects the air cavity 11 with the atmospheric environment. The exhaust hole 13 is arranged near the edge of the bottom wall 12. The capacitor 20 is arranged in the sensor body 10, and the capacitor 20 has a deformation zone 21 corresponding to the open end of the air cavity 11. When the deformation zone 21 is deformed, the capacitance of the capacitor 20 can be changed. The vibration membrane 30 is arranged on the side of the capacitor 20 away from the sensor body 10. The present application uses the pressure sensor 100 as an example. Figure 1 Taking the middle direction as an example, the vibration membrane 30 is arranged on the upper side of the capacitor 20. When the vibration membrane 30 is under pressure, the vibration membrane 30 acts on the deformation area 21 to change the capacitance of the capacitor 20, so as to detect the pressure according to the capacitance of the capacitor 20.

[0041] During pressure sensing by the pressure sensor 100, the vibrating membrane 30 is subjected to pressure and bends toward the interior of the air cavity 11. This bending of the vibrating membrane 30 drives the deformation zone 21 to deform, thereby changing the capacitance of the capacitor 20. The pressure is detected by measuring the change in capacitance of the capacitor 20, with each capacitance value of the capacitor 20 corresponding to a pressure value. When the vibrating membrane 30 is subjected to different pressures, the vibrating membrane 30 bends to different degrees. When the vibrating membrane 30 with different degrees of bending acts on the deformation zone 21, the deformation zone 21 of the capacitor 20 deforms and bends to different degrees, resulting in different capacitances for the capacitor 20. Under different pressures, the capacitor 20 has different capacitances. When the vibrating membrane 30 is bent toward the air cavity 11 under the action of pressure, the gas in the air cavity 11 is discharged from the air cavity 11 through the exhaust hole 13. The gas in the air cavity 11 will not generate resistance to the movement of the vibrating membrane 30. The gas in the air cavity 11 has no limitation on the vibration bending deflection of the vibrating membrane 30. When the vibrating membrane 30 is subjected to different pressures, it can be ensured that the vibrating membrane 30 bends smoothly toward the air cavity 11 to act on the deformation zone 21, thereby changing the capacitance of the capacitor 20, thereby improving the detection linearity and sensitivity of the pressure sensor 100.

[0042] 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. The gas in the air cavity 11 will not generate resistance to the movement of the vibrating membrane 30. The vibrating membrane 30 can reliably act on the deformation zone 21 to change the capacitance of the capacitor 20, thereby improving the detection linearity and sensitivity of the pressure sensor 100.

[0043] In some embodiments of the present invention, Figure 1As shown, the capacitor 20 may include a dielectric layer 22, a first metal electrode 23, and a second metal electrode 24. The first metal electrode 23 is disposed on the surface of the sensor body 10 near the capacitor 20 and on the inner wall of the air cavity 11. It should be noted that the inner wall of the air cavity 11 includes the inner wall of the bottom wall 12 of the air cavity 11 and the inner wall of the side wall of the air cavity 11. The first metal electrode 23 is disposed on the inner wall of the bottom wall 12 of the air cavity 11. Furthermore, the first metal electrode 23 may also be disposed on the inner wall of the side wall of the air cavity 11. The first metal electrode 23 may also be disposed on the end surface of the sensor body 10 near the capacitor 20. The first metal electrode 23 is attached to the end of the sensor body 10 near the capacitor 20, the inner wall of the bottom wall 12 of the air cavity 11, and the inner wall of the side wall of the air cavity 11. A dielectric layer 22 is disposed on the side of the first metal electrode 23 away from the sensor body 10. 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 a 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, such as Figure 1 As shown, the second metal electrode 24 is disposed at the upper end of the sensor body 10, extending radially in the sensor body 10. The vibrating membrane 30 is disposed on a side of the second metal electrode 24 that is distal to the sensor body 10. The vibrating membrane 30 can be attached to the surface of the second metal electrode 24 that is distal to the sensor body 10. When pressure is applied to the vibrating membrane 30, the pressure acts on the second metal electrode 24, causing the second metal electrode 24 to extend into the air cavity 11 and contact the dielectric layer 22 disposed on the inner wall, thereby changing the capacitance of the capacitor 20.

[0044] Specifically, during the process of pressure detection by the pressure sensor 100, the vibrating membrane 30 is bent toward the air cavity 11 under the action of pressure, and the gas in the air cavity 11 is discharged from the air cavity 11 through the exhaust hole 13. When the vibrating membrane 30 bends toward the air cavity 11, it drives the deformation area 21 of the second metal electrode 24 to bend toward the air cavity 11. After the deformation area 21 of the second metal electrode 24 bends toward the air cavity 11, it contacts the dielectric layer 22. As the pressure increases, the contact area between the second metal electrode 24 and the dielectric layer 22 on the inner wall surface of the bottom wall 12 of the air cavity 11 increases, causing the capacitance of the capacitor 20 to change, thereby detecting the pressure by testing the capacitance change of the capacitor 20. Such a setting can accurately detect the pressure and improve the detection sensitivity and linearity of the pressure sensor 100. Moreover, since the air cavity 11 is connected to the atmospheric environment, the gas in the air cavity 11 has no limitation on the vibration 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, further improving the detection linearity and sensitivity of the pressure sensor 100, and enabling the pressure sensor 100 to perform high-precision pressure detection.

[0045] In some embodiments of the present invention, Figure 1 As shown, the dielectric layer 22 has a first avoidance hole 25, and the first metal electrode 23 has a second avoidance hole 26. The first avoidance hole 25 is connected to the exhaust hole 13 through the second avoidance hole 26. Furthermore, 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 connects the air cavity 11 and the second avoidance hole 26, the second avoidance hole 26 connects the first avoidance hole 25 and the exhaust hole 13, and the exhaust hole 13 connects the second avoidance hole 26 and the atmospheric environment. Such a setting can achieve the effect of connecting the air cavity 11 and the atmospheric environment, and can simplify the structure of the pressure sensor 100.

[0046] In some embodiments of the present invention, dielectric layer 22 can be configured as a metal oxide layer, for example, made of an oxide of a metal such as silver, aluminum, or titanium. Furthermore, dielectric layer 22 has a thickness of 1 nm to 1 μm. This configuration ensures the performance of dielectric layer 22 and the functionality of capacitor 20.

[0047] In some embodiments of the present invention, the first metal electrode 23 and the second metal electrode 24 are both made of a metal material with a thickness of 100 nm to 1 μm and good electrical conductivity. Preferably, the metal electrode material is silver, aluminum, titanium, gold, or the like. This arrangement can ensure the working performance of the capacitor 20 and also ensure the service life of the first metal electrode 23 and the second metal electrode 24. The vibration membrane 30 is an elastic film with a thickness of 1 μm to 10 μm. Preferably, the material of the elastic film is polydimethylsiloxane, but the present invention is not limited thereto. The material of the elastic film can also be set to a material that has the same function as polydimethylsiloxane, such as silicon.

[0048] In some embodiments of the present invention, the exhaust hole 13 is tangent to the edge of the bottom wall 12, which can also be understood as the exhaust hole 13 being 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 relative 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. Furthermore, the exhaust hole 13 is configured as a circular hole. Such a configuration enables the exhaust hole 13 to be arranged at the edge of the bottom wall 12 of the air cavity 11, effectively avoiding the formation of a high-density gas compression area between the vibrating membrane 30 and the inner wall of the air cavity 11, ensuring that the gas in the air cavity 11 has no limitation on the vibration bending deflection of the vibrating membrane 30, and is more conducive to better contact between the first metal electrode 23 and the second metal electrode 24, further improving the detection linearity and sensitivity of the pressure sensor 100.

[0049] 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, etc. The diameter of the exhaust hole 13 can be reasonably selected and arranged according to actual needs. When the vibrating membrane 30 is deformed by force, by setting 2μm≤R≤10μm, it can ensure that the gas in the air cavity 11 is discharged from the exhaust hole 13 in a timely manner. 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, further improving the detection linearity and sensitivity of the pressure sensor 100, thereby making the diameter of the exhaust hole 13 appropriate.

[0050] In some embodiments of the present invention, a plurality of exhaust holes 13 can be provided, and the plurality of exhaust holes 13 are sequentially spaced apart along the circumference of the bottom wall 12. Furthermore, the plurality of exhaust holes 13 are sequentially spaced apart along the circumference of the bottom wall 12. Wherein, 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, it can be ensured that the gas between the vibrating membrane 30 and the inner wall of the air cavity 11 is discharged from the plurality of exhaust holes 13 in a timely manner along the entire circumference of the air cavity 11, thereby avoiding excessive local pressure between the vibrating membrane 30 and the inner wall of the air cavity 11, and preventing the vibration bending deflection of the vibrating membrane 30 from being restricted due to untimely gas discharge.

[0051] In some embodiments of the present invention, the total volume of the vents 13 is smaller than the volume of the air cavity 11. If the air cavity 11 is not connected to the atmosphere, it is susceptible to external temperature fluctuations and can experience relatively large temperature drifts. By making the total volume of the vents 13 smaller than the volume of the air cavity 11, the temperature drift of the pressure sensor 100 is reduced while ensuring sufficient capacitance between the first metal electrode 23 and the second metal electrode 24 upon contact.

[0052] In some embodiments of the present invention, the shape of the deformation zone 21 is adapted to the cross-sectional shape of the air cavity 11, and the cross-sectional shape of the deformation zone 21 is the same as the cross-sectional shape of the air cavity 11. Furthermore, the cross-sectional shape of the deformation zone 21 and the cross-sectional shape of the air cavity 11 are both circular. When the vibration membrane 30 is deformed under force, the shape of the deformation zone 21 is adapted to the cross-sectional shape of the air cavity 11, so that the deformation zone 21 can be smoothly deformed and bent toward the inside of the air cavity 11, and the capacitance of the capacitor 20 can be changed when the vibration membrane 30 acts on the deformation zone 21, thereby ensuring the working reliability of the pressure sensor 100.

[0053] It should be noted that if Figure 1As shown, the second metal electrode 24 is located below the vibrating membrane 30. When the pressure sensor 100 operates in contact mode, the first metal electrode 23 and the second metal electrode 24 are separated by a metal oxide layer with a high dielectric constant (i.e., the dielectric layer 22), which can have a higher capacitance value and significantly improve the detection sensitivity of the pressure sensor 100.

[0054] like Figure 4 As shown, it is a comparison chart of the capacitance change trend of the existing pressure sensor and the pressure sensor 100 of the present application. Figure 4 The upper curve in the middle shows the relationship between the capacitance of the pressure sensor 100 of the present application and the pressure change. Figure 4 The lower curve in the middle shows the relationship between the capacitance of the existing pressure sensor and the pressure. As can be seen from the figure, the linearity and sensitivity of the pressure sensor 100 of the present application are significantly improved.

[0055] In some embodiments of the present invention, the pressure sensor 100 may include a light-emitting portion, which may be provided on the sensor body 10. The light-emitting portion may be provided as a component with a light-emitting function, such as a lamp. By providing the light-emitting portion, the pressure sensor 100 may have a lighting function, which facilitates users to find the pressure sensor 100 in insufficient light conditions.

[0056] In some embodiments of the present invention, a filter is provided in the exhaust hole 13 . The filter has a filtering function, which can prevent foreign particles from entering the air cavity 11 and avoid the particles from accumulating in the air cavity 11 .

[0057] like Figure 3 As shown, a method for preparing a pressure sensor 100 according to an embodiment of the present invention is provided. 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 a bottom wall 12 of the air cavity 11 is provided with an exhaust hole 13. The capacitor 20 is provided in the sensor body 10 and has a deformation zone 21 corresponding to the open end of the air cavity 11. 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 provided on the surface of the sensor body 10 close to the capacitor 20 and on the inner wall surface of the air cavity 11. The side of the first metal electrode 23 away from the sensor body 10 is provided with a dielectric layer 22. The preparation method includes the following steps:

[0058] S10 , selecting a substrate as the sensor body 10 , and etching the sensor body 10 to form an air cavity 11 .

[0059] It should be noted that a silicon substrate is selected as the sensor body 10 , photoresist is spin-coated on the surface of the sensor body 10 and photolithography is performed to form a patterned mask layer, and the air cavity 11 is formed on the sensor body 10 by anisotropic dry etching.

[0060] S20 , etching an exhaust hole 13 on the bottom wall 12 of the air cavity 11 .

[0061] It should be noted that the exhaust holes 13 are formed near the edge of the bottom wall 12 of the air cavity 11 by anisotropic dry etching.

[0062] S30 , forming a first metal electrode 23 on the inner wall surface of the air cavity 11 by magnetron sputtering.

[0063] It should be noted that a first metal electrode 23 is formed by growing a metal film by magnetron sputtering 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 face of the sensor body 10 close to the capacitor 20, so as to set the first metal electrode 23 on the sensor body 10.

[0064] S40 , forming a dielectric layer 22 on a surface of the first metal electrode 23 away from the sensor body 10 by atomic layer deposition.

[0065] 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 .

[0066] S50 , forming a second metal electrode 24 on the surface of the vibration membrane 30 close to the capacitor 20 by magnetron sputtering.

[0067] It should be noted that the second metal electrode 24 is formed by magnetron sputtering a metal thin film on the surface of the vibration membrane 30 close to the capacitor 20 .

[0068] S60 , attaching the second metal electrode 24 to the air cavity 11 and bonding it to the sensor body 10 .

[0069] It should be noted that if Figure 1 As shown, 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 .

[0070] Among them, through the above-mentioned preparation method of the pressure sensor 100, a pressure sensor 100 that meets the requirements can be prepared, the pressure detection sensitivity of the pressure sensor 100 can be improved, and the linearity of the pressure sensor 100 can also be improved.

[0071] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0072] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A pressure sensor, characterized in that: include: A sensor body, the sensor body having an air cavity with one end open, a bottom wall of the air cavity being provided with an exhaust hole, and the exhaust hole being arranged near an edge of the bottom wall; a capacitor and a vibrating membrane, wherein the capacitor is provided on the sensor body and has a deformation zone corresponding to the open end of the air cavity; The vibration membrane is arranged on the side of the capacitor away from the sensor body. When the vibration membrane is subjected to pressure, the capacitance of the capacitor is changed by the vibration membrane acting on the deformation zone to detect pressure based on the capacitance of the capacitor. The exhaust hole is tangent to the edge of the bottom wall.

2. The pressure sensor according to claim 1, wherein The exhaust hole is a circular hole; The diameter of the exhaust hole is R, which satisfies the relationship: 2μm≤R≤10μm.

3. The pressure sensor according to claim 1, wherein There are a plurality of exhaust holes, and the plurality of exhaust holes are spaced apart in sequence along the circumference of the bottom wall.

4. The pressure sensor according to any one of claims 1 to 3, characterized in that The total volume of the exhaust holes is smaller than the volume of the air cavity.

5. The pressure sensor according to any one of claims 1 to 3, characterized in that: 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 dielectric layer is provided on the side of the first metal electrode away from the sensor body. The second metal electrode is provided on the side of the dielectric layer away from the first metal electrode and forms the deformation zone. When the vibrating membrane is subjected to pressure, the vibrating membrane acts on the second metal electrode, causing the second metal electrode to extend into the air cavity and contact the dielectric layer provided on the inner wall surface, thereby changing the capacitance of the capacitor.

6. The pressure sensor according to claim 5, characterized in that The dielectric layer has a first avoidance hole, the first metal electrode has a second avoidance hole, and the first avoidance hole is connected to the exhaust hole through the second avoidance hole.

7. The pressure sensor according to claim 5, characterized in that The dielectric layer is configured as a metal oxide layer.

8. The pressure sensor according to claim 1, wherein The shape of the deformation zone is adapted to the cross-sectional shape of the air cavity.

9. A method for preparing a pressure sensor, characterized in that: The pressure sensor includes 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 exhaust hole is tangent to the edge of the bottom wall. The capacitor is provided in the sensor body and has a deformation zone corresponding to the open end of the air cavity. The vibrating membrane is provided on the side of the capacitor away from the sensor body. The capacitor includes a dielectric layer, a first metal electrode, and a second metal electrode. The first metal electrode is provided on a surface of the sensor body close to the capacitor and on an inner wall surface of the air cavity. The dielectric layer is provided on a side of the first metal electrode away from the sensor body. The preparation method includes the following steps: Selecting a substrate base as the sensor body, and etching the air cavity on the sensor body; Etching the exhaust hole on the bottom wall of the air cavity; forming the first metal electrode on the inner wall surface of the air cavity by magnetron sputtering; forming the dielectric layer on a surface of the first metal electrode away from the sensor body by atomic layer deposition; forming the second metal electrode 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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