MEMS pressure sensor

Abstract

The utility model provides an MEMS pressure sensor, which comprises a base, the top surface of the base is provided with a cavity, and the inner wall of the cavity is provided with a first-stage pressure sensing diaphragm and a second-stage pressure sensing diaphragm from top to bottom in sequence; a sealing cavity is defined by the first-stage pressure sensing diaphragm, the second-stage pressure sensing diaphragm and the inner wall of the concave cavity, the sealing cavity is filled with pressure guiding liquid, and the inner diameter of the sealing cavity is sequentially decreased from top to bottom. A detection cavity is defined by the second-stage pressure sensing diaphragm and the bottom of the concave cavity, a fixed electrode is arranged on the bottom face of the detection cavity, a movable electrode matched with the fixed electrode is arranged on the bottom face of the second-stage pressure sensing diaphragm, and the fixed electrode and the movable electrode form a first capacitor. When the first-stage pressure sensing diaphragm is pressed to bend and deform downwards, the pressure guiding liquid in the sealing cavity presses the second-stage pressure sensing diaphragm to bend and deform downwards, and the deformation quantity of the second-stage pressure sensing diaphragm is larger than that of the first-stage pressure sensing diaphragm, so that the deformation quantity of the first-stage pressure sensing diaphragm is amplified, and the sensitivity of the MEMS pressure sensor is improved.

Description

Technical Field

[0001] The present application relates to the technical field of pressure sensors, and in particular to a MEMS pressure sensor. Background Art

[0002] Micro-electromechanical systems (MEMS) are micro devices or systems that integrate microstructures, micro-actuators, micro-sensors, signal processing and control circuits, and even interfaces, communications, and power supplies. MEMS has the advantages of low manufacturing cost, low mass, small size, high performance, and easy integration. In recent years, MEMS technology has developed rapidly and has been widely used, such as in aerospace, automobiles, biotechnology, and other fields.

[0003] Among micro sensors, pressure sensors are a common and important type of sensor. There are generally piezoresistive, piezoelectric, capacitive and other principle pressure sensors. Among the current sensors, piezoresistive pressure sensors have good linearity, but average accuracy and low sensitivity. Compared with them, capacitive pressure sensors have the advantages of high accuracy and small temperature drift.

[0004] For example, the capacitive pressure sensor described in patent 201680043400.8 measures the pressure value by forming a capacitor in the cavity between the first electrode and the second electrode. However, the sensitivity of this sensor is also reduced due to the protruding base in the cavity.

[0005] The sensor described in patent 201610868540.0 is a contact sensor. The upper and lower electrodes of the sensor are set in the external fluid, which can measure the pressure in the fluid. However, different fluids have different dielectric constants, which requires different capacitance calibrations and is cumbersome to operate. In addition, in this patent, the film is used as an active electrode, and its normal displacement is relatively small. If its sensitivity needs to be improved, the size of the device needs to be increased.

[0006] In the pressure sensor described in patent 201710688334.6, the thickness of the island structure is increased on the moving film to achieve overload resistance, but at the same time it also loses the high-range effect and its sensitivity will also be lost accordingly.

[0007] The above patents all show that in the design of capacitive pressure sensors, the sensitivity of the sensor is limited due to the limitations of the pressure-sensitive film. Generally, in order to have a greater sensitivity in the design of capacitive pressure sensors, the film needs to have a larger deflection, and the thickness of the film will be as small as possible or the film area will be increased. Since it is difficult to ensure the airtightness of very thin films, it is not easy to reduce the thickness of the film in manufacturing, and the sensor size is relatively large or the sensitivity is low. Summary of the invention

[0008] The present application provides a MEMS pressure sensor, which solves the problem that the sensitivity of the current MEMS capacitive pressure sensor is limited due to the limitations of the pressure-sensitive film.

[0009] The present application provides a MEMS pressure sensor, including a base, wherein a concave cavity is provided on the top surface of the base, and a first annular groove and a second annular groove are provided on the inner wall of the concave cavity in sequence from top to bottom, a primary pressure-sensitive diaphragm is sealed and installed in the first annular groove, and a secondary pressure-sensitive diaphragm is sealed and installed in the second annular groove; the primary pressure-sensitive diaphragm, the secondary pressure-sensitive diaphragm and the inner wall of the concave cavity together form a sealed cavity, the interior of the sealed cavity is filled with a pressure-conducting liquid, and the inner diameter of the sealed cavity decreases in sequence from top to bottom; the secondary pressure-sensitive diaphragm and the bottom of the concave cavity together form a detection cavity, the bottom surface of the detection cavity is provided with a fixed electrode, the bottom surface of the secondary pressure-sensitive diaphragm is provided with a movable electrode matching the fixed electrode, and the fixed electrode and the movable electrode constitute a first capacitor.

[0010] In the technical solution provided by the present application, a primary pressure-sensitive diaphragm and a secondary pressure-sensitive diaphragm are provided, and an active electrode is provided on the bottom surface of the secondary pressure-sensitive diaphragm, and a fixed electrode matching the active electrode is provided on the bottom surface of the detection cavity; since the sealed cavity is filled with a pressure-conducting liquid, and the inner diameter of the sealed cavity decreases successively from top to bottom, when the primary pressure-sensitive diaphragm is bent downward under pressure, the pressure-conducting liquid in the sealed cavity will compel the secondary pressure-sensitive diaphragm to bend downward, and since the lower inner diameter of the sealed cavity is smaller than the upper inner diameter, in order to maintain the constant volume of the sealed cavity, the deformation of the secondary pressure-sensitive diaphragm will be greater than the deformation of the primary pressure-sensitive diaphragm, thereby achieving an amplification of the deformation of the primary pressure-sensitive diaphragm, thereby improving the sensitivity of the MEMS pressure sensor.

[0011] In some embodiments, a reference electrode is provided between the fixed electrode and the movable electrode, and the reference electrode and the movable electrode constitute a second capacitor, and the capacitance difference between the first capacitor and the second capacitor is configured to be linearly related to the pressure applied to the primary pressure-sensitive diaphragm; by providing a reference electrode between the fixed electrode and the movable electrode, the capacitance difference between the first capacitor and the second capacitor changes linearly with the pressure sensed by the pressure sensor, which, on the one hand, can suppress the influence of the capacitance on the external environment's temperature, air pressure and other factors, eliminate the zero drift caused by environmental factors, and thus improve the accuracy of the MEMS pressure sensor detection data; on the other hand, it can solve the problem of MEMS pressure sensor output nonlinearity under a specific diaphragm stiffness.

[0012] In some embodiments, the movable electrode and the reference electrode are circular electrodes, the fixed electrode is an annular electrode, the outer diameter of the fixed electrode matches the outer diameter of the movable electrode, the inner diameter of the fixed electrode matches the outer diameter of the reference electrode, and the fixed electrode, the reference electrode, and the movable electrode are coaxially arranged. This structural design can avoid mutual influence between the reference electrode and the fixed electrode. The outer annular area of ​​the movable electrode corresponds to the top surface of the fixed electrode to form a first capacitor, and the middle circular area of ​​the active electrode corresponds to the top surface of the reference electrode to form a second capacitor.

[0013] In some embodiments, the MEMS pressure sensor also includes a signal processing chip, which is electrically connected to the first capacitor and the second capacitor respectively, and calculates the pressure data applied to the primary pressure-sensitive diaphragm according to the capacitance difference between the first capacitor and the second capacitor.

[0014] In some embodiments, a gas balance channel connected to the outside is opened on the side wall of the detection chamber. By opening a gas balance channel connected to the outside on the side wall of the detection chamber, the air pressure in the detection chamber is always maintained constant. When the secondary pressure-sensitive diaphragm is deformed downward, the air in the detection chamber will not be compressed. The air pressure in the detection chamber is maintained constant, which will not in turn affect the deformation of the secondary pressure-sensitive diaphragm, thereby further improving the accuracy of the detection data.

[0015] Furthermore, the inlet and outlet of the gas balance channel are provided with a waterproof and breathable membrane to prevent moisture from entering the detection cavity through the gas balance channel and affecting the dielectric constant of the medium in the detection cavity, thereby further ensuring the accuracy of the detection data.

[0016] In some embodiments, the base includes a cover layer, a core layer and a substrate layer arranged in sequence from top to bottom, the first annular groove is arranged on the top surface of the core layer, and the second annular groove is arranged on the top surface of the substrate layer; the bottom surface of the cover layer and the top surface of the core layer are connected by bonding, and the bottom surface of the core layer and the top surface of the substrate layer are connected by bonding. This structural design facilitates the processing of the sensor.

[0017] In some embodiments, the base is made of materials such as silicon, silicon carbide or glass.

[0018] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings in this application are used to illustrate preferred embodiments, so that those skilled in the art can clearly understand various other advantages and benefits, and should not be considered as limitations of this application. In addition, the same reference numerals are used throughout the drawings to represent the same or similar components.

[0020] Figure 1 This is a schematic cross-sectional structure diagram of a MEMS pressure sensor in one embodiment of the present application;

[0021] Figure 2 A schematic diagram of the arrangement of the first capacitor and the second capacitor in one embodiment of the present application;

[0022] Icons: 1. Base; 110. Cover layer; 120. Core layer; 130. Substrate layer; 2. Concave cavity; 3. Primary pressure-sensitive diaphragm; 4. Secondary pressure-sensitive diaphragm; 5. Sealed cavity; 6. Detection cavity; 7. Fixed electrode; 8. Movable electrode; 9. First capacitor; 10. Reference electrode; 11. Second capacitor; 12. Gas balance channel; 13. Waterproof and breathable membrane. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two (including two), unless otherwise clearly and specifically defined.

[0026] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0027] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0028] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0029] See also Figure 1-Figure 2 The embodiment of the present application provides a MEMS pressure sensor, including a base 1, a concave cavity 2 is provided on the top surface of the base 1, and a first annular groove and a second annular groove are provided on the inner wall of the concave cavity 2 in sequence from top to bottom, a primary pressure-sensitive diaphragm 3 is sealed and installed in the first annular groove, and a secondary pressure-sensitive diaphragm 4 is sealed and installed in the second annular groove; the primary pressure-sensitive diaphragm 3, the secondary pressure-sensitive diaphragm 4 and the inner wall of the concave cavity 2 are surrounded by a sealed cavity 5, the sealed cavity 5 is filled with a pressure-conducting liquid, and the inner diameter of the sealed cavity 5 decreases in sequence from top to bottom; the secondary pressure-sensitive diaphragm 4 and the bottom of the concave cavity 2 are surrounded by a detection cavity 6, the bottom surface of the detection cavity 6 is provided with a fixed electrode 7, the bottom surface of the secondary pressure-sensitive diaphragm 4 is provided with a movable electrode 8 matched with the fixed electrode 7, and the fixed electrode 7 and the movable electrode 8 constitute a first capacitor 9.

[0030] In the technical solution provided in the embodiment of the present application, a primary pressure-sensitive diaphragm 3 and a secondary pressure-sensitive diaphragm 4 are provided, and an active electrode 8 is provided on the bottom surface of the secondary pressure-sensitive diaphragm 4, and a fixed electrode 7 matching the active electrode 8 is provided on the bottom surface of the detection cavity 6; since the sealed cavity 5 is filled with a pressure-conducting liquid, and the inner diameter of the sealed cavity 5 decreases successively from top to bottom, when the primary pressure-sensitive diaphragm 3 is pressurized to bend downward, the pressure-conducting liquid in the sealed cavity 5 will compel the secondary pressure-sensitive diaphragm 4 to bend downward, and since the lower inner diameter of the sealed cavity 5 is smaller than the upper inner diameter, in order to maintain the constant volume of the sealed cavity 5, the deformation of the secondary pressure-sensitive diaphragm 4 will be greater than the deformation of the primary pressure-sensitive diaphragm 3, thereby achieving an amplification of the deformation of the primary pressure-sensitive diaphragm 3, thereby improving the sensitivity of the MEMS pressure sensor.

[0031] In a specific implementation, the pressure-conducting liquid may be a liquid pressure-conducting liquid that is difficult to compress, and can well transmit the pressure on the primary pressure-sensitive diaphragm 3 .

[0032] Please continue reading Figure 1 , Figure 2 In some embodiments, a reference electrode 10 is provided between the fixed electrode 7 and the movable electrode 8, and the reference electrode 10 and the movable electrode 8 constitute a second capacitor 11. Under a small deflection deformation, the capacitance difference between the first capacitor 9 and the second capacitor 11 is linearly related to the pressure applied to the primary pressure-sensitive diaphragm 3; by providing the reference electrode 10 between the fixed electrode 7 and the movable electrode 8, the capacitance difference between the first capacitor 9 and the second capacitor 11 is linearly related to the pressure felt by the pressure sensor. On the one hand, the capacitance can be suppressed from being affected by factors such as the temperature and air pressure of the external environment, and the zero drift caused by environmental factors can be eliminated, thereby improving the accuracy of the detection data of the MEMS pressure sensor.

[0033] Please continue reading Figure 2 In a specific embodiment, the movable electrode 8 and the reference electrode 10 are circular electrodes, and the fixed electrode 7 is an annular electrode. The outer diameter of the fixed electrode 7 matches the outer diameter of the movable electrode 8, and the inner diameter of the fixed electrode 7 matches the outer diameter of the reference electrode 10 (the inner diameter of the fixed electrode 7 is slightly larger than the outer diameter of the reference electrode 10 to avoid the reference electrode 10 blocking the facing area between the fixed electrode 7 and the movable electrode 8). The fixed electrode 7, the reference electrode 10, and the movable electrode 8 are coaxially arranged. This structural design can avoid mutual influence between the reference electrode 10 and the fixed electrode 7. The outer annular area of ​​the movable electrode 8 corresponds to the top surface of the fixed electrode 7 to form a first capacitor 9, and the middle circular area of ​​the movable electrode 8 corresponds to the top surface of the reference electrode 10 to form a second capacitor 11.

[0034] Assume that the top surface area of ​​the fixed electrode 7 is S1, and the top surface area of ​​the reference electrode 10 is S2; when the secondary pressure-sensitive diaphragm 4 is in the initial state, the distance between the fixed electrode 7 and the movable electrode 8 is d1, and the distance between the reference electrode 10 and the movable electrode 8 is d2. The relationship between the structural parameters of the first capacitor 9 and the second capacitor 11 is configured as S1 / S2=d1 / d2, the purpose of which is to make the initial capacitance of the first capacitor 9 and the second capacitor 11 equal, and the initial capacitance difference between the first capacitor 9 and the second capacitor 11 is 0, corresponding to the state when the sensor detects the pressure is 0.

[0035] The capacitance of the first capacitor 9 is:

[0036]

[0037] The capacitance of the second capacitor 11 is:

[0038]

[0039] Where ε0 is the dielectric constant of vacuum, ε γ is the relative dielectric constant of the medium in the detection cavity 6; S1 is the top surface area of ​​the fixed electrode 7, S2 is the top surface area of ​​the reference electrode 10; d1′ is the distance between the fixed electrode 7 and the movable electrode 8, d2′ is the distance between the reference electrode 10 and the movable electrode 8; when d1′=d1, d2′=d2, according to S1 / S2=d1 / d2, it can be obtained that C1=C2.

[0040] In some embodiments, the MEMS pressure sensor further includes a signal processing chip (not shown in the figure), the signal processing chip is electrically connected to the first capacitor 9 and the second capacitor 11 respectively, and the signal processing chip calculates the pressure data applied to the primary pressure-sensitive diaphragm 3 according to the capacitance difference between the first capacitor 9 and the second capacitor 11. The signal processing chip in this embodiment can be an ASIC (Application Specific Integrated Circuit) chip.

[0041] Please continue reading Figure 1 In some embodiments, a gas balance channel 12 connected to the outside is opened on the side wall of the detection chamber 6. By opening the gas balance channel 12 connected to the outside on the side wall of the detection chamber 6, the air pressure in the detection chamber 6 is always maintained constant. When the secondary pressure-sensitive diaphragm 4 deforms downward, the air in the detection chamber 6 will not be compressed. The air pressure in the detection chamber 6 remains constant, which will not in turn affect the deformation of the secondary pressure-sensitive diaphragm 4, further improving the accuracy of the detection data.

[0042] Please continue reading Figure 1Furthermore, a waterproof and breathable membrane 13 is provided at the inlet and outlet of the gas balance channel 12 to prevent moisture from entering the detection cavity 6 through the gas balance channel 12 and affecting the dielectric constant of the medium in the detection cavity 6, thereby further ensuring the accuracy of the detection data.

[0043] Please continue reading Figure 1 In some embodiments, the base 1 includes a cover layer 110, a core layer 120 and a substrate layer 130 arranged in sequence from top to bottom, the first annular groove is arranged on the top surface of the core layer 120, and the second annular groove is arranged on the top surface of the substrate layer 130; the bottom surface of the cover layer 110 and the top surface of the core layer 120 are connected by bonding, and the bottom surface of the core layer 120 and the top surface of the substrate layer 130 are connected by bonding. This structural design facilitates the processing of the sensor.

[0044] In some embodiments, the base 1 is made of materials such as silicon, silicon carbide or glass.

[0045] In this embodiment, the fixed electrode 7 is generated on the bottom surface of the detection cavity 6 by magnetron sputtering, and the movable electrode 8 is generated on the bottom surface of the secondary pressure-sensitive diaphragm 4 by magnetron sputtering. A support column is provided at the bottom of the reference electrode 10 for fixing the reference electrode 10 inside the detection cavity 6. The reference electrode 10 can also be generated by magnetron sputtering.

[0046] When the pressure sensor of this embodiment is working, the pressure of the medium to be measured is sensed by the primary pressure-sensitive diaphragm 3. When the primary pressure-sensitive diaphragm 3 is bent downward under pressure, the sealed cavity 5 can no longer be compressed. In order to keep the volume of the sealed cavity 5 constant, the secondary pressure-sensitive diaphragm 4 at the bottom of the sealed cavity 5 will be bent downward under pressure. And because the inner diameter of the sealed cavity 5 decreases from top to bottom, the downward deformation of the secondary pressure-sensitive diaphragm 4 will be greater than the deformation of the primary pressure-sensitive diaphragm 3, so as to maintain the constant volume of the sealed cavity 5. In this way, the deformation of the primary pressure-sensitive diaphragm 3 can be amplified, thereby improving the sensitivity of the MEMS pressure sensor; when the secondary pressure-sensitive diaphragm 4 is bent downward, , driving the active electrode 8 on the bottom surface of the secondary pressure-sensitive diaphragm 4 to move downward, thereby reducing the distance between the active electrode 8 and the fixed electrode 7 and the reference electrode 10, thereby causing the capacitance value of the first capacitor 9 and the second capacitor 11 to change. By configuring the capacitance difference between the first capacitor 9 and the second capacitor 11 to be linearly related to the pressure applied to the primary pressure-sensitive diaphragm 3, on the one hand, the capacitance can be suppressed from being affected by factors such as the temperature and air pressure of the external environment, and the zero drift caused by environmental factors can be eliminated, thereby improving the accuracy of the MEMS pressure sensor; on the other hand, it can solve the problem of MEMS pressure sensor output nonlinearity under a specific diaphragm stiffness.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A MEMS pressure sensor, characterized in that: The invention comprises a base (1), wherein a concave cavity (2) is provided on the top surface of the base (1), and a first annular groove and a second annular groove are provided on the inner wall of the concave cavity (2) in order from top to bottom; a primary pressure-sensitive diaphragm (3) is sealedly installed in the first annular groove, and a secondary pressure-sensitive diaphragm (4) is sealedly installed in the second annular groove; the primary pressure-sensitive diaphragm (3), the secondary pressure-sensitive diaphragm (4) and the inner wall of the concave cavity (2) are combined to form a sealed cavity (5), the interior of the sealed cavity (5) is filled with a pressure-conducting liquid, and the inner diameter of the sealed cavity (5) decreases in order from top to bottom; the secondary pressure-sensitive diaphragm (4) and the bottom of the concave cavity (2) are combined to form a detection cavity (6), the bottom surface of the detection cavity (6) is provided with a fixed electrode (7), the bottom surface of the secondary pressure-sensitive diaphragm (4) is provided with a movable electrode (8) matched with the fixed electrode (7), and the fixed electrode (7) and the movable electrode (8) constitute a first capacitor (9).

2. A MEMS pressure sensor according to claim 1, characterized in that: A reference electrode (10) is provided between the fixed electrode (7) and the movable electrode (8), and the reference electrode (10) and the movable electrode (8) form a second capacitor (11), and the capacitance difference between the first capacitor (9) and the second capacitor (11) is configured to be linearly related to the pressure applied to the primary pressure-sensitive diaphragm (3).

3. A MEMS pressure sensor according to claim 2, characterized in that: The movable electrode (8) and the reference electrode (10) are circular electrodes, the fixed electrode (7) is an annular electrode, the outer diameter of the fixed electrode (7) matches the outer diameter of the movable electrode (8), the inner diameter of the fixed electrode (7) matches the outer diameter of the reference electrode (10), and the fixed electrode (7), the reference electrode (10) and the movable electrode (8) are coaxially arranged.

4. A MEMS pressure sensor according to claim 2, characterized in that: The MEMS pressure sensor also includes a signal processing chip, and the signal processing chip is electrically connected to the first capacitor (9) and the second capacitor (11) respectively.

5. The MEMS pressure sensor according to claim 1, characterized in that: The side wall of the detection cavity (6) is provided with a gas balance channel (12) connected to the outside.

6. A MEMS pressure sensor according to claim 5, characterized in that: The inlet and outlet of the gas balance channel (12) are provided with waterproof and breathable membranes (13).

7. The MEMS pressure sensor according to claim 1, characterized in that: The base (1) comprises a cover layer (110), a core layer (120) and a substrate layer (130) which are arranged in sequence from top to bottom; the first annular groove is arranged on the top surface of the core layer (120), and the second annular groove is arranged on the top surface of the substrate layer (130); the bottom surface of the cover layer (110) and the top surface of the core layer (120) are connected by bonding, and the bottom surface of the core layer (120) and the top surface of the substrate layer (130) are connected by bonding.

8. The MEMS pressure sensor according to claim 1, characterized in that: The base (1) is made of silicon, silicon carbide or glass material.

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