Piezoelectric resonant pressure sensor and pressure compensation system

Abstract

The utility model discloses a piezoelectric resonant pressure sensor and a pressure compensation system, and relates to the technical field of sensitive element and sensor manufacturing in the electronic core industry, and the piezoelectric resonant pressure sensor comprises a piezoelectric assembly which is directly or indirectly connected with an external circuit; the resonant structure is connected with the piezoelectric assembly and is provided with a resonant film; the pressure sensitive structure is arranged on the side, away from the piezoelectric assembly, of the resonant film; the side, close to the resonant film, of the pressure sensitive structure is provided with at least one resonant cavity, the side, away from the resonant film, of the pressure sensitive structure is provided with a pressure cavity, and pressure received by the pressure cavity can be transmitted to the resonant film on the resonant structure. The projection of at least one resonant cavity is located outside the projection of the pressure cavity. According to the piezoelectric resonant pressure sensor, the pressure can be detected through the change of the resonant frequency of the resonant structure, and the piezoelectric resonant pressure sensor can have higher bearing capacity, so that the piezoelectric resonant pressure sensor can have a larger pressure detection range.

Description

Technical Field

[0001] The present application relates to the technical field of sensitive components and sensor manufacturing in the core electronics industry, and in particular to a piezoelectric resonant pressure sensor and a pressure compensation system. Background Art

[0002] Pressure sensors can convert received pressure signals into electrical signals according to certain rules and output the electrical signals to other devices. They are sensitive components. Pressure sensors are widely used in defense, automobile, petroleum, aerospace, smart hardware and other technical fields, and belong to the core electronic industry technology field.

[0003] With the development of micro-electro-mechanical system (MEMS) technology, pressure sensors can be combined with MEMS technology to realize mass production of pressure sensors and improve the production efficiency of pressure sensors.

[0004] According to different working principles, pressure sensors can be divided into resonant pressure sensors, piezoresistive pressure sensors, capacitive pressure sensors, piezoelectric pressure sensors, piezoelectric resonant pressure sensors, etc. Among them, piezoelectric resonant pressure sensors have the advantages of good stability and high accuracy, and can be used in scenarios with high accuracy requirements and harsh working environments.

[0005] Based on the structure of the existing piezoelectric resonant pressure sensor, the piezoelectric resonant pressure sensor has a relatively complex structure, low detection efficiency and a small detection range. Utility Model Content

[0006] The present application provides a piezoelectric resonant pressure sensor and a pressure compensation system, which can detect pressure through changes in the resonant frequency of a resonant structure, thereby improving measurement accuracy, and because of a relatively simple structure, it is easier to achieve miniaturization and mass production.

[0007] In a first aspect, the present application provides a piezoelectric resonant pressure sensor for use in the core electronics industry. The piezoelectric resonant pressure sensor comprises:

[0008] A piezoelectric component is directly or indirectly connected to an external circuit;

[0009] A resonant structure connected to the piezoelectric component, wherein the resonant structure has a resonant film;

[0010] A pressure sensitive structure is arranged on a side of the resonant film away from the piezoelectric component;

[0011] At least one resonance cavity is formed on a side of the pressure sensitive structure close to the resonance film, and the resonance film closes or does not close at least a part of the resonance cavity. A pressure cavity is formed on a side of the pressure sensitive structure away from the resonance film, and the pressure received by the pressure cavity can be transmitted to the resonance film on the resonance structure.

[0012] In a direction of the pressure sensitive structure toward the piezoelectric component, a projection of at least one of the resonant cavities is outside a projection of the pressure cavity.

[0013] The opening of the pressure cavity in the above structure can form a pressure-sensitive film, and the setting of the resonant cavity forms a resonant film. The pressure-sensitive film can be stacked on part of the resonant structure and part of the piezoelectric component to form a film structure with a higher thickness and pressure-sensitive function. At this time, the thicker pressure-sensitive film directly bears the pressure, and the stress transmitted to the resonant film and the piezoelectric component through the side of the resonant cavity and the integrated laminated structure on the entire pressure-sensitive film is converted into stress on the resonant film and the piezoelectric component. In order to ensure sensitivity, the resonant film and the piezoelectric component are usually thin and cannot withstand the axial stress caused by large pressure. The above structure solves this problem, improves the pressure-bearing capacity of the structure, expands the pressure detection range, and ensures the linearity of the structure in the pressure measurement range. And because the structure of the piezoelectric resonant pressure sensor of the present application is integrated into one through the MEMS process, it can be more easily miniaturized and easier to achieve mass production.

[0014] The piezoelectric resonant pressure sensor provided in the example of the present application can withstand a larger pressure to be detected, thereby improving the pressure measurement range of the piezoelectric resonant pressure sensor and expanding the measurement range of the piezoelectric resonant pressure sensor, so that the piezoelectric resonant pressure sensor can be widely used in the core technology field of the electronics industry.

[0015] In some examples, the pressure sensitive structure includes:

[0016] A pressure sensitive portion is provided on a side of the resonant structure away from the piezoelectric component, and at least one of the resonant cavities is provided in the pressure sensitive portion;

[0017] A pressure receiving part, which is integrally provided with the pressure sensitive part, the pressure receiving part is provided at a side of the pressure sensitive part away from the resonant structure, and the pressure chamber is opened in the pressure receiving part;

[0018] A pressure-sensitive film is disposed in the middle of the pressure-sensitive portion, one side of the pressure-sensitive film is located in the pressure chamber, and the external pressure received by the pressure chamber acts on the pressure-sensitive film.

[0019] The pressure sensitive structure includes an integrally arranged pressure sensitive portion and a pressure receiving portion. The pressure receiving portion may be provided with two layers, namely a thinner transition layer and a thicker main layer. The layer structure here is not a physical layer structure, but a simulated layer structure to reflect the opening positions of the pressure cavity and the resonance cavity. The pressure sensitive structure itself is an integrated structure, such as an integrated SI wafer. The resonance cavity is opened in the pressure sensitive portion, the pressure cavity is opened in the main layer, and the transition layer is a transition part located in the area between the resonance cavity and the pressure cavity. The pressure sensitive portion is connected to the resonance structure, the resonance cavity is opened in the pressure sensitive portion, the resonance structure is supported around the resonance cavity, and the pressure cavity is opened in the main layer.

[0020] The pressure-sensitive part, transition layer and main body layer arranged in one piece can form the pressure-sensitive structure of the present application. The pressure-sensitive part is connected to the resonant structure, and is the key part of the resonance effect in the piezoelectric resonant pressure sensor. At least one resonant cavity is provided in the pressure-sensitive part, and the resonant cavity, the resonant structure and the piezoelectric component together constitute a resonant system. When the pressure to be measured acts on the pressure-sensitive structure, the pressure to be measured is transmitted to the resonant film through the anchor point, and then transmitted to the piezoelectric component by the resonant film. During the transmission process, the pressure to be measured is successively converted into stress on the resonant film and stress on the piezoelectric component. When the pressure to be measured is transmitted to the resonant component, the resonant frequency of the resonant film in the resonant component will change. The piezoelectric component uses the inverse piezoelectric effect to excite the vibration of the resonant film, and uses the positive piezoelectric effect to detect the change in the resonant frequency of the resonant film, thereby detecting the value of the pressure to be measured.

[0021] In some examples, the pressure sensitive structure is formed by processing the SI wafer, the resonant structure is formed by processing the SOI wafer, and the device layer of the SOI wafer is bonded to one side of the SI wafer.

[0022] After the processing of the SOI wafer is completed, the SOI wafer and the SI wafer need to be bonded. During this bonding process, the device layers of the SOI wafer and the SI wafer are tightly attached together by precisely controlling the bonding conditions (such as temperature, pressure, time, etc.). The bonded resonant structure not only retains the high performance characteristics of the resonant structure, but also achieves a sensitive response to external pressure, thereby improving the stability and reliability of the entire system.

[0023] In some examples, at least one of the resonant cavities is opened on a side of the SI wafer close to the SOI wafer, and the pressure cavity is opened on a side of the SI wafer away from the SOI wafer.

[0024] When the pressure to be measured acts on the pressure sensitive structure, the pressure is first transmitted to the resonant film through the anchor point. The resonant film can deform when subjected to pressure. In the process of being transmitted to the resonant film, the pressure to be measured is converted into stress on the film.

[0025] Next, the stress on the resonant film is further transmitted to the piezoelectric component. The piezoelectric component is a device that can convert mechanical stress into electrical signals, using the piezoelectric effect to achieve this conversion process. During the transmission process, the pressure to be measured is again converted into stress on the piezoelectric component, which then generates an electrical signal output.

[0026] During the transmission of the pressure to be measured, the resonant film will produce a resonance change. This resonance change is a direct reflection of the pressure to be measured, and the specific value of the pressure to be measured can be inferred by measuring the change in the resonance frequency. In addition, the piezoelectric component uses the inverse piezoelectric effect to excite the vibration of the resonant film, and at the same time uses the direct piezoelectric effect to detect the change in the resonant frequency of the resonant film, thereby detecting the value of the pressure to be measured. The inverse piezoelectric effect refers to the phenomenon that piezoelectric materials produce deformation under the action of an electric field. By applying an electric field, the piezoelectric component can be stimulated to produce resonance, thereby further detecting the pressure to be measured.

[0027] In some examples, the sum of the opening depth of the resonance cavity and the opening depth of the pressure cavity is less than the thickness of the SI wafer.

[0028] The above setting can make the opening positions of the pressure chamber and the resonance chamber in the SI wafer staggered instead of being on the same horizontal line. The staggered position can be used as an anchor point for transferring stress, which can better transfer the stress received on the pressure sensitive film to the resonance film through the anchor point. During the transfer process, the resonance film can be driven to produce a resonance change, or the piezoelectric component can be used to use the inverse piezoelectric effect to excite the change of the resonance frequency, and then the specific value of the pressure to be measured can be detected, ensuring that the piezoelectric detection is carried out normally, and making the accuracy of the piezoelectric detection more accurate.

[0029] In some examples, after the device layer is bonded to the SI wafer, the buried oxide layer and the substrate layer are removed from the SOI wafer to form the resonant structure, and an oxide layer is formed at the bonding position between the device layer and the SI wafer.

[0030] In some examples, a cover is provided on a side of the piezoelectric component facing away from the resonant structure, and the cover and the piezoelectric component enclose a sealed cavity; and / or,

[0031] A protection structure is arranged on a side of the piezoelectric component away from the resonant structure, and the protection structure covers the surface of the piezoelectric component.

[0032] The side of the piezoelectric component facing away from the resonant structure is equipped with a cover. The cover and the piezoelectric component together enclose a sealed cavity, which can be set as a vacuum cavity or a cavity with a specific medium, such as nitrogen, ammonia, xenon, etc. This sealed structure ensures that the piezoelectric component is not disturbed by the external environment during operation, such as dust, moisture or other impurities that may affect its performance. This setting not only extends the service life of the piezoelectric component, but also ensures the stability of its performance, thereby improving the reliability and durability of the entire piezoelectric resonant pressure sensor.

[0033] The pressure in the sealed cavity and the pressure in the pressure cavity may have a certain pressure difference, and an absolute pressure or relative pressure sensor can be formed by calculating the absolute pressure difference or the relative pressure difference. Among them, the absolute pressure difference means that when the sealed cavity is a vacuum cavity, the pressure value in the sealed cavity is zero, and the detection value of the pressure cavity by the piezoelectric resonant pressure sensor is the pressure value received by the pressure cavity. At this time, the sensor is an absolute pressure sensor. The relative pressure difference means that the sealed cavity is a cavity with a specific pressure. At this time, there is a medium in the sealed cavity and the pressure is maintained at a certain value. The detection value of the pressure cavity by the piezoelectric resonant pressure sensor needs to be subtracted from the pressure value in the sealed cavity to obtain the pressure value received by the pressure cavity. At this time, the sensor is a relative pressure sensor.

[0034] In a second aspect, the present application provides a pressure compensation system for a piezoelectric resonant pressure sensor, comprising:

[0035] At least one piezoelectric resonant pressure sensor as described above; and

[0036] At least one compensation sensor, wherein the compensation sensor is spaced apart from or integrated with the piezoelectric resonant pressure sensor;

[0037] The compensation sensor can receive ambient pressure, and the piezoelectric resonant pressure sensor can receive the pressure to be measured and the ambient pressure. The value of the pressure to be measured can be obtained by subtracting the detection value of the compensation sensor from the detection value of the piezoelectric resonant pressure sensor.

[0038] The compensation sensor can receive interference factors caused by environmental influences, the piezoelectric resonant pressure sensor can receive the pressure to be measured and the environmental pressure, and the value of the pressure to be measured can be obtained by subtracting the detection value of the compensation sensor from the detection value of the piezoelectric resonant pressure sensor.

[0039] The compensation sensor will be affected by the environment, and the piezoelectric resonant pressure sensor can receive the pressure to be measured and will also be affected by the same environment. The value of the pressure to be measured can be obtained by subtracting the detection value of the compensation sensor from the detection value of the piezoelectric resonant pressure sensor.

[0040] In order to achieve the goal of accurately measuring pressure, a piezoelectric resonant pressure sensor with higher accuracy is set up. This piezoelectric resonant pressure sensor can accurately capture and measure pressure changes in various environments. However, environmental factors themselves may interfere with the sensor, resulting in deviations in the measurement results. In order to solve this problem, the present application proposes a pressure compensation system, which eliminates the interference of environmental influences on the measurement results by introducing a compensation sensor.

[0041] In a third aspect, the present application provides a method for preparing a piezoelectric resonant pressure sensor, which is applicable to the above-mentioned piezoelectric resonant pressure sensor; the method is used to process an SI wafer and an SOI wafer into the piezoelectric resonant pressure sensor, and the method comprises:

[0042] Take an SI wafer and open at least one resonant cavity on one side of the SI wafer;

[0043] The above steps can utilize advanced micro-nano processing technology to open at least one resonant cavity on the SI wafer.

[0044] Taking an SOI wafer, and setting the device layer thickness of the SOI wafer to the thickness of the resonant film;

[0045] The above steps can set the thickness of the device layer to the ideal thickness of the resonant film. This step ensures that the resonant film has sufficient flexibility and mechanical strength to meet the working requirements of the piezoelectric resonant pressure sensor.

[0046] Inverting the SOI wafer, and bonding the device layer to a side of the SI wafer having the resonant cavity;

[0047] The above steps can bond the device layer to the SI wafer. This step utilizes the unique structure and excellent material properties of the SOI wafer to achieve a stable connection of the device layer.

[0048] Thinning the SOI wafer, removing the substrate layer and the buried oxide layer during the thinning process;

[0049] The above steps can successfully remove the substrate layer and buried oxide layer by precisely controlling the thinning process, so that only the device layer remains on the SOI wafer. This step not only simplifies the structure of the sensor, but also improves its sensitivity. Part of the structure of the device layer can be used as a resonant film that can cooperate with the resonant cavity.

[0050] Processing a piezoelectric component on a side of the device layer away from the device layer, and reserving an external conductive structure on the piezoelectric component;

[0051] The above steps can process the piezoelectric component on the side of the device layer away from the SI wafer. The existence of the piezoelectric component is the key to realizing the conversion of the sensor electrical signal. At the same time, an external conductive structure can be reserved on the piezoelectric component to connect the output signal of the sensor to the external circuit.

[0052] A pressure chamber is opened on a side of the SI wafer away from the device layer.

[0053] The above steps can realize the opening of the pressure chamber, and then the cover can be set as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the examples or prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some examples of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 This is a schematic diagram of the structure of a piezoelectric resonant pressure sensor in an example of the present application;

[0056] Figure 2 This is a schematic diagram of the structure of a piezoelectric resonant pressure sensor in an example of the present application when there is no cover;

[0057] Figure 3 A schematic diagram of a top view of the structure of a piezoelectric resonant pressure sensor in an example of the present application without a cover;

[0058] Figure 4 For this application, an example Figure 3 Schematic diagram of the cross-sectional view of the structure of the medium-pressure electric resonant pressure sensor in the AA direction when there is no cover;

[0059] Figure 5 For this application, an example Figure 3 Schematic diagram of the cross-sectional view of the structure of the medium-pressure electric resonant pressure sensor in the BB direction when there is no cover;

[0060] Figure 6 This is a schematic diagram of the structure of a piezoelectric resonant pressure sensor in an example of the present application when there is no cover and no lead electrode and protective layer;

[0061] Figure 7 It is a schematic diagram of a top view of another structure of a piezoelectric resonant pressure sensor in an example of the present application, in which lead electrodes and a protective layer are not provided;

[0062] Figure 8 It is a schematic diagram of a top view of another structure of a piezoelectric resonant pressure sensor in an example of the present application, in which lead electrodes and a protective layer are not provided;

[0063] Fig. 9 It is a schematic diagram of a top view of another structure of a piezoelectric resonant pressure sensor in an example of the present application, in which lead electrodes and a protective layer are not provided;

[0064] Fig.10 It is a schematic diagram of a top view of another structure of a piezoelectric resonant pressure sensor in an example of the present application, in which lead electrodes and a protective layer are not provided;

[0065] Fig.11 It is a schematic diagram of a top view of another structure of a piezoelectric resonant pressure sensor in an example of the present application, in which lead electrodes and a protective layer are not provided;

[0066] Fig.12 It is a schematic diagram of a top view structure when a piezoelectric resonant pressure sensor in an example of the present application is applied to a pressure compensation system without lead electrodes and a protective layer;

[0067] Fig.13 It is a top view schematic diagram of another structure of the piezoelectric resonant pressure sensor in an example of the present application when it is applied to a pressure compensation system without the lead electrode and the protective layer;

[0068] Fig.14 A schematic diagram of a process for preparing a piezoelectric resonant pressure sensor in an example of the present application;

[0069] Fig.15 This is a schematic diagram of the structure of an unprocessed SI wafer in an example of the present application;

[0070] Fig.16 This is a schematic diagram of the structure of an SI wafer after a resonant cavity is opened in an example of the present application;

[0071] Fig.17 This is a schematic diagram of the structure of an unprocessed SOI wafer in an example of the present application;

[0072] Fig.18 It is a structural schematic diagram of an example of the present application when the SOI wafer is inverted and bonded toward the SI wafer;

[0073] Fig.19 This is a schematic diagram of the structure after the SOI wafer in an example of the present application is inverted and bonded to the SI wafer;

[0074] Fig. 20 This is a schematic diagram of the structure in an example of the present application after the SOI wafer is bonded to the SI wafer and the buried oxide layer and the substrate layer are removed;

[0075] Fig.21 This is a schematic diagram of a structure after a piezoelectric component is deposited on a side facing away from a device layer in an example of the present application;

[0076] Fig. 22 This is a schematic diagram of a structure in which a piezoelectric component is deposited on one side away from the device layer and the second electrode layer is etched in an example of the present application;

[0077] Fig.23 This is a schematic diagram of a structure in which a protective structure is provided on the outside of a piezoelectric component in an example of the present application;

[0078] Fig.24 When a protective structure is set on the outside of the piezoelectric component in an example of the present application and the viewing angle is switched to the Figure 3 Schematic diagram of the structure in the middle BB direction;

[0079] Fig.25 This is a schematic diagram of a structure in which a connecting channel is provided on the second electrode layer of a piezoelectric component in an example of the present application;

[0080] Fig.26 This is a schematic diagram of a structure in which a connecting channel is provided on the first electrode layer of a piezoelectric component in an example of the present application;

[0081] Fig. 27 This is a schematic diagram of the structure when a top layer of metal is deposited after connecting channels are respectively opened on the first electrode layer and the second electrode layer in a piezoelectric component in an example of the present application;

[0082] Fig.28 A schematic diagram of the structure of a piezoelectric component in an example of the present application after patterning the top metal layer;

[0083] Fig.29 When a protective structure is set on the outside of the piezoelectric component in an example of the present application and the viewing angle is switched to the Figure 3 Schematic diagram of the structure in the AA direction;

[0084] Fig.30 This is a schematic diagram of the structure after a pressure chamber is opened on the side of the pressure sensitive structure facing away from the piezoelectric component in an example of the present application;

[0085] Fig.31 This is a schematic diagram of the structure before the cover is processed in an example of the present application;

[0086] Fig.32 This is a schematic diagram of the structure of the cover after molding in an example of the present application;

[0087] Fig.33 This is a schematic diagram of the structure after the cover is installed in an example of the present application;

[0088] Fig.34 This is a structural schematic diagram of a piezoelectric resonant pressure sensor in an example of the present application when a cover is provided but no protective structure is provided.

[0089] Reference numerals:

[0090] 10. Piezoelectric resonant pressure sensor; 20. Compensation sensor; 100. Piezoelectric component; 110. First electrode layer; 120. Piezoelectric layer; 130. Second electrode layer; 140. First electrode structure; 150. Second electrode structure; 200. Resonance component; 210. Resonance structure; 211. Fixed part; 212. Resonance film; 220. Pressure sensitive structure; 221. Pressure sensitive part; 2211. Resonance cavity; 2212. Pressure sensitive film; 222. Pressure receiving part; 223. Pressure cavity; 230. Oxide layer; 240. Anchor point; 300. SI wafer; 400. SOI wafer; 410. Device layer; 420. Buried oxide layer; 430. Substrate layer; 500. Cover; 600. Protection structure. DETAILED DESCRIPTION

[0091] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific examples described here are only used to explain the present application and are not used to limit the present application.

[0092] In the piezoelectric resonant pressure sensor of the related art, the piezoelectric resonant pressure sensor can be miniaturized and then applied to micro-electromechanical systems (MEMS), which are micro-systems that integrate micron-level mechanical devices, integrated circuits, sensors, actuators, and signal processing and control circuits on one or more chips. The size of such a system is usually only a few millimeters or even smaller.

[0093] Due to the use of micromachining technology, MEMS technology can mass-produce various micro sensors, actuators, micro components and micro machines. These micro devices have the characteristics of small size, light weight, low power consumption, stable performance, high reliability, high integration, intelligence, large production batch, low cost, and easy large-scale production. Therefore, they are widely used in aviation, aerospace, automobile, biomedicine, environmental monitoring, military and other fields.

[0094] As an important measuring tool, the accuracy and response speed of piezoelectric resonant pressure sensor are crucial for many applications. In recent years, with the increasing demand for miniaturization and mass production, new piezoelectric resonant pressure sensor arrangements have emerged. The present application discloses a piezoelectric resonant pressure sensor arrangement combining a piezoelectric component and a resonant structure.

[0095] To achieve the above purpose, please refer to Figure 1-Figure 34 As shown, the first aspect of the present application proposes a piezoelectric resonant pressure sensor, which can make the piezoelectric resonant pressure sensor have a greater tolerance and thus a larger pressure detection range. Also, due to its relatively simple structure, it is easier to achieve miniaturization and mass production.

[0096] The piezoelectric resonant pressure sensor mentioned in the example of this application can be combined with MEMS technology to achieve mass production of piezoelectric resonant pressure sensors and improve the production efficiency of piezoelectric resonant pressure sensors.

[0097] The piezoelectric resonant pressure sensor mentioned in the example of this application can output a corresponding electrical signal based on the received pressure to be detected, and is a sensitive element.

[0098] The piezoelectric resonant pressure sensor can use a thicker pressure-sensitive film to sense pressure, and then convert it into stress on the piezoelectric resonator through the anchor point 240. The piezoelectric stack of the piezoelectric resonator is generally thin and cannot withstand the axial stress caused by a large pressure. The above structure solves this problem, improves the pressure-bearing capacity of the structure, expands the pressure detection range, and ensures the linearity of the structure in the pressure measurement range. The above setting enables the piezoelectric resonant pressure sensor to be widely used in the core electronic industry technology field.

[0099] In the present application, the anchor point 240 refers to the area where the pressure sensitive film is connected to the resonant film. The external pressure acting on the pressure sensitive film can be transmitted to the anchor point 240 during the deformation of the pressure sensitive film, and act on the resonant film through the anchor point 240. During the transmission process, the external pressure can be converted through the anchor point 240 to improve the pressure bearing capacity of the pressure chamber, thereby improving the pressure detection range. The piezoelectric resonator can be a combination of the resonant structure and the piezoelectric component in the present application.

[0100] Reference Figures 1 to 5 In some examples, the piezoelectric resonant pressure sensor 10 is applied to the core electronics industry. The piezoelectric resonant pressure sensor 10 includes a piezoelectric component 100 , a resonant structure 210 , and a pressure sensitive structure 220 .

[0101] The piezoelectric component 100 is directly or indirectly connected to an external circuit; the resonant structure 210 is connected to the piezoelectric component 100, and the resonant structure 210 has a resonant film 212; the pressure sensitive structure 220 is arranged on a side of the resonant film 212 away from the piezoelectric component 100;

[0102] At least one resonance cavity 2211 is provided on a side of the pressure sensitive structure 220 close to the resonance film 212. The resonance film 212 closes or does not close at least a part of the resonance cavity 2211. A pressure cavity 223 is provided on a side of the pressure sensitive structure 220 away from the resonance film 212. The pressure received by the pressure cavity 223 can be transmitted to the resonance film 212 on the resonance structure 210.

[0103] In the direction of the pressure sensitive structure 220 toward the piezoelectric assembly 100 , the projection of at least one resonance cavity 2211 is outside the projection of the pressure cavity 223 .

[0104] The opening of the pressure cavity 223 in the above structure can form a pressure-sensitive film 2212, and the setting of the resonant cavity 2211 forms a resonant film 212. The pressure-sensitive film 2212 can be stacked on part of the resonant structure 210 and part of the piezoelectric component 100 to form a film structure with a higher thickness and pressure-sensitive function. At this time, the thicker pressure-sensitive film 2212 directly bears the pressure, and is transmitted to the resonant film 212 and the piezoelectric component 100 through the side of the resonant cavity 2211 and the integrated stacked structure on the entire pressure-sensitive film 2212, and converted into stress on the resonant film 212 and the piezoelectric component 100. In order to ensure sensitivity, the resonant film 212 and the piezoelectric component 100 are usually thin and cannot withstand the axial stress caused by large pressure. The above structure solves this problem, improves the pressure-bearing capacity of the structure, expands the pressure detection range, and ensures the linearity of the structure in the pressure measurement range. And because the structure of the piezoelectric resonant pressure sensor 10 of the present application is integrated into one through the MEMS process, it can be more easily miniaturized and easier to achieve mass production.

[0105] The piezoelectric resonant pressure sensor 10 is mainly composed of three parts: a piezoelectric component 100, a resonant structure 210 and a pressure-sensitive structure 220. The piezoelectric component 100 can be used as the core part of the piezoelectric resonant pressure sensor 10 to drive the resonator to vibrate and detect the frequency change of the resonator caused by the pressure to be measured. The above driving and detection are based on the piezoelectric effect. The piezoelectric component 100 is connected to the external circuit directly or indirectly to realize signal transmission and processing. The resonant structure 210 is the main part that generates resonance, and the pressure-sensitive structure 220 is used to receive external pressure and transmit the external pressure to the resonant film 212 on the resonant structure 210.

[0106] The resonant structure 210 and the pressure sensitive structure 220 are connected to each other. The resonant structure 210 can be connected to the piezoelectric component 100 to form the core structure (piezoelectric resonator) of the sensor. The pressure sensitive structure 220 is arranged on the other side of the resonant structure 210 and is responsible for sensing the change of the pressure to be measured. The above structure enables the sensor to detect pressure by changing the resonant frequency of the resonant structure 210 when it is under pressure, thereby improving the measurement accuracy.

[0107] The resonant cavity 2211 and the pressure cavity 223 are both opened on the pressure sensitive structure 220. The resonant cavity 2211 is opened on the side of the pressure sensitive structure 220 close to the resonant structure 210, and is supported by the resonant structure 210 around the resonant cavity 2211, and the resonant cavity 2211 may be closed or not. The existence of the resonant cavity 2211 is to ensure the normal operation of the resonant structure 210 and to provide space for the movement of the resonant structure 210. The pressure cavity 223 is used to receive external pressure. When pressure acts on the pressure cavity 223, an anchor point 240 for pressure transmission can be formed between the pressure cavity 223 and the resonant cavity 2211, and the pressure is transmitted to the resonant film 212 and the piezoelectric component 100 through the anchor point 240 structure, forming stress on the resonant film 212 and the piezoelectric component 100.

[0108] The resonant cavity 2211 is matched with the resonant structure 210. The part of the resonant structure 210 located above the opening of the resonant cavity 2211 can form a resonant film 212. The resonant film 212 is driven by the piezoelectric component 100 to resonate. When the pressure is transmitted to the resonant film 212 and the piezoelectric component 100 through the anchor point 240 structure, stress is formed on the resonant film 212 and the piezoelectric component 100. The stress will cause the resonant frequency of the resonant film 212 to change, and the change is detected by the piezoelectric component 100.

[0109] In the direction from the pressure sensitive structure 220 to the piezoelectric assembly 100, the projection of at least one resonant cavity 2211 is located outside the projection of the pressure cavity 223. This arrangement cleverly utilizes the interaction between the resonant cavity 2211 and the pressure cavity 223, so that the sensor can more sensitively capture pressure changes when subjected to pressure, thereby improving the measurement accuracy of the sensor. At least one resonant cavity 2211 can also be partially arranged inside the projection of the pressure cavity 223.

[0110] The selection of the piezoelectric component 100 is important for the performance and stability of the sensor, so the selection of materials and processing technology can be carefully considered as needed during the setting and manufacturing process. The signal conversion part of the piezoelectric component 100 can be made of piezoelectric film materials, piezoelectric ceramics, polymer piezoelectric materials, nano piezoelectric materials and other materials to meet the needs of different application scenarios. It can be preferably a piezoelectric film material, which can be AlN, ScAlN, PZT, ZnO, LiNbO3, etc.

[0111] The resonant structure 210 and the pressure sensitive structure 220 of the present application may cooperate to form a resonant component 200 .

[0112] Reference Figure 4 In some examples, the pressure sensitive structure 220 includes:

[0113] The pressure sensitive portion 221 is disposed on a side of the resonant structure 210 away from the piezoelectric component 100 , and at least one resonant cavity 2211 is opened in the pressure sensitive portion 221 ;

[0114] The pressure receiving portion 222 is integrally provided with the pressure sensitive portion 221 . The pressure receiving portion 222 is provided on a side of the pressure sensitive portion 221 away from the resonant structure 210 . The pressure chamber 223 is provided in the pressure receiving portion 222 .

[0115] A pressure-sensitive film 2212 is disposed in the middle of the pressure-sensitive portion 221 . One side of the pressure-sensitive film 2212 is located in the pressure chamber 223 . The external pressure received by the pressure chamber 223 acts on the pressure-sensitive film 2212 .

[0116] The pressure sensitive structure 220 includes an integrally arranged pressure sensitive portion 221 and a pressure receiving portion 222. The pressure receiving portion 222 may be provided with two layers, namely a thinner transition layer and a thicker main body layer. The layer structure here is not a physical layer structure, but a simulated layer structure to reflect the opening positions of the pressure cavity 223 and the resonance cavity 2211. The pressure sensitive structure 220 itself is an integrated structure, such as an integrated SI wafer 300. The resonance cavity 2211 is opened in the pressure sensitive portion 221, the pressure cavity 223 is opened in the main body layer, and the transition layer is a transition part located in the area between the resonance cavity 2211 and the pressure cavity 223. The pressure sensitive portion 221 is connected to the resonance structure 210, the resonance cavity 2211 is opened in the pressure sensitive portion 221, the resonance structure 210 is supported around the resonance cavity 2211, and the pressure cavity 223 is opened in the main body layer.

[0117] The integrally arranged pressure-sensitive portion 221, transition layer and main body layer can form the pressure-sensitive structure 220 of the present application. The pressure-sensitive portion 221 is connected to the resonant structure 210 and is a key part of the resonance effect in the piezoelectric resonant pressure sensor 10. At least one resonant cavity 2211 is provided in the pressure-sensitive portion 221, and the resonant cavity 2211, the resonant structure 210 and the piezoelectric component 100 together constitute a resonant system. When the pressure to be measured acts on the pressure-sensitive structure 220, the pressure to be measured is transmitted to the resonant film 212 through the anchor point 240, and then transmitted to the piezoelectric component 100 by the resonant film 212. During the transmission process, the pressure to be measured is converted into stress on the resonant film 212 and stress on the piezoelectric component 100 in turn. When the pressure to be measured is transmitted to the resonance component 200, the resonance frequency of the resonance film 212 in the resonance component 200 will change. The piezoelectric component 100 uses the inverse piezoelectric effect to excite the resonance film 212 to vibrate, and at the same time uses the direct piezoelectric effect to detect the change in the resonance frequency of the resonance film 212, thereby detecting the value of the pressure to be measured.

[0118] The pressure chamber 223 is also a key part of the piezoelectric resonant pressure sensor 10. The pressure chamber 223 is opened in the main body layer. The function of the pressure chamber 223 is to provide the sensor with an environment that is in direct contact with the pressure to be measured, ensuring that the sensor can accurately sense the change of the pressure to be measured. The setting of the pressure chamber 223 needs to take into account factors such as the use environment, operating temperature and pressure range of the sensor to ensure that it has good sealing and stability.

[0119] Reference Figure 3 and Figure 4 The pressure cavity 223 at least penetrates the entire main body layer, and at most penetrates the transition layer. The pressure sensitive portion 221 forms a pressure sensitive film 2212 in the area corresponding to the pressure cavity 223. The layer structure here is not a physical layer structure, but a simulated layer structure to reflect the position of the pressure cavity 223 and the resonant cavity 2211. The pressure sensitive structure 220 itself is an integrated structure, such as an integrated SI wafer 300. The transition layer is a transition part located in the area between the resonant cavity 2211 and the pressure cavity 223.

[0120] At least one resonant cavity 2211 is located around the pressure sensitive film 2212, and the pressure received by the pressure cavity 223 can act on the pressure sensitive film 2212 and be transmitted to the resonant structure 210. Specifically, the pressure received by the pressure cavity 223 can be transmitted to the resonant film 212 on the resonant structure 210 through the anchor point 240.

[0121] Since the resonance cavity 2211 is provided in the pressure sensitive part 221, and the pressure cavity 223 is provided in the main body layer, the transition layer is a transition part located in the region between the resonance cavity 2211 and the pressure cavity 223. The pressure cavity 223 can penetrate the main body layer and the transition layer at the same time (in this case, there will be no transition layer, because the pressure cavity 223 and the resonance cavity 2211 are spatially intertwined, and in this case, the pressure cavity 223 and the resonance cavity 2211 will not be connected), or the pressure cavity 223 can only penetrate the main body layer, and such a setting can form a channel that is in direct contact with the external environment. The setting of the transition layer can facilitate the processing of the pressure cavity 223. During the processing of the pressure cavity 223, the transition layer can be used to identify the processing depth of the pressure cavity 223. It should be understood that the pressure cavity 223 can also only penetrate the main body layer and retain the transition layer.

[0122] The pressure chamber 223 may be a unidirectionally opened pressure groove, the bottom of the pressure groove may be located at a pressure-sensitive film 2212, the pressure-sensitive film 2212 may be a part of the pressure-sensitive portion 221, the resonance chamber 2211 may be arranged in the peripheral area of ​​the pressure-sensitive film 2212, the pressure-sensitive film 2212 may have a high sensitivity characteristic, the pressure-sensitive film 2212 may transfer the pressure to be measured received in the pressure chamber 223 to the resonance structure 210, and drive the resonance frequency of the resonance structure 210 to change, the piezoelectric component 100 utilizes the inverse piezoelectric effect to excite the resonance structure 210 to vibrate, and utilizes the positive piezoelectric effect to detect the change in the resonance frequency of the resonance structure 210, and then detects the value of the pressure to be measured.

[0123] In the above structure, the pressure-sensitive film 2212 can be used to overlap the thickness of the resonant structure 210, and the thicker pressure-sensitive film 2212 can be used to sense the pressure. Then, the stress is transferred to the piezoelectric resonator through the membrane structure (anchor point 240 part) shared by the pressure-sensitive film 2212 and the piezoelectric resonator. This solves the problem that the piezoelectric stack of the resonator is generally thin and cannot withstand the axial stress caused by a large pressure, improves the pressure-bearing capacity of the structure, expands the pressure detection range, and ensures the linearity of the structure within the pressure measurement range.

[0124] When the pressure chamber 223 receives the pressure to be measured, the pressure sensitive film 2212 will be acted upon by force and slightly deformed. In order to amplify the deformation and convert it into a measurable electrical signal, at least one resonant cavity 2211 is provided on the peripheral side of the pressure sensitive film 2212.

[0125] The region where the resonant structure 210 closes or does not close the opening of the resonant cavity 2211 may form a resonant film 212 , and a side of the resonant film 212 facing away from the resonant cavity 2211 is connected to the piezoelectric component 100 .

[0126] The above-mentioned resonant frequency change can be detected and recorded by connecting to the corresponding electronic measuring equipment through an external circuit breaker, thereby achieving accurate measurement of the pressure to be measured. In addition, the piezoelectric resonant pressure sensor 10 of the present application can be integrally formed using MEMS technology, which is convenient for mass production.

[0127] In addition, the piezoelectric resonant pressure sensor 10 of the present application also has a wide range of application prospects. It can play a huge role in the fields of industrial automation, aerospace, environmental monitoring, etc. For example, in industrial automation, the piezoelectric resonant pressure sensor 10 can be used to monitor the operating status of mechanical equipment, detect faults in time and issue early warnings; in aerospace, the piezoelectric resonant pressure sensor 10 can be used to measure the changes in air pressure of aircraft or rockets during flight, providing accurate data support for flight control; in environmental monitoring, the piezoelectric resonant pressure sensor 10 can be used to measure key parameters such as atmospheric pressure and water level, providing an important basis for environmental protection and weather forecasting.

[0128] Reference Figure 4 and Figure 5 In some examples, the resonant structure 210 may include a fixed portion 211 and a resonant film 212 connected to each other, a first side of the fixed portion 211 is connected to the piezoelectric component 100 , and a second side of the fixed portion 211 is connected to the pressure sensitive structure 220 .

[0129] The first side of the resonant film 212 is connected to the piezoelectric component 100 , and the second side of the resonant film 212 closes or does not close the opening of the resonant cavity 2211 .

[0130] The resonant structure 210 may have certain vibration characteristics and energy conversion efficiency. The resonant structure 210 may be specifically formed by interconnecting a fixed portion 211 and a resonant film 212. The resonant structure 210 may be able to excite the resonant film 212 to vibrate by utilizing the inverse piezoelectric effect through the piezoelectric component 100. When the pressure sensitive structure 220 receives the pressure to be measured and transmits it to the resonant component 200, it will cause the resonant frequency of the resonant film 212 in the resonant component 200 to change. The piezoelectric component 100 may excite the resonant film 212 to vibrate by utilizing the inverse piezoelectric effect and at the same time may detect the change in the resonant frequency of the resonant film 212 by utilizing the positive piezoelectric effect, thereby detecting the value of the pressure to be measured, thereby ensuring the detection of the pressure to be measured.

[0131] The fixing portion 211 is naturally formed during the processing of the resonant structure 210 . The fixing portion 211 can make the disposition of the resonant film 212 more stable and reliable.

[0132] The resonant film 212 is a functional part of the resonant structure 210. The piezoelectric component 100 can use the inverse piezoelectric effect to excite the resonant film 212 to vibrate. The pressure to be measured can act on the pressure-sensitive film 2212 and be transmitted to the resonant film 212 and the piezoelectric component 100 through the anchor point 240, and then converted into stress on the resonant film 212 and the piezoelectric component 100.

[0133] One side of the resonant film 212 is connected to the piezoelectric component 100 , and the other side of the resonant film 212 closes or does not close the opening of the resonant cavity 2211 .

[0134] The pressure sensitive film 2212 can also be formed by thinning the opening position after the pressure sensitive structure 220 opens the pressure cavity 223. The side of the pressure sensitive film 2212 facing away from the pressure cavity 223 is connected to the resonant structure 210. The pressure received by the pressure cavity 223 can act on the pressure sensitive film 2212 and be transmitted to the resonant structure 210.

[0135] The setting and optimization of the pressure sensitive structure 220 can improve the performance and accuracy of the piezoelectric resonant pressure sensor 10. In the piezoelectric resonant pressure sensor 10 of the present application, the pressure sensitive film 2212 in the pressure sensitive structure 220 can be combined with the resonant film 212 in the resonant structure 210 to achieve accurate perception and response to the pressure to be measured, thereby improving the performance of the piezoelectric resonant pressure sensor 10.

[0136] The main functional part of the pressure sensitive structure 220 is the pressure sensitive film 2212 . The pressure sensitive film 2212 is the thinnest part of the pressure sensitive structure 220 that corresponds to the pressure cavity 223 after the pressure cavity 223 is formed in the pressure sensitive structure 220 .

[0137] The pressure sensitive film 2212 can be deformed when subjected to external force, and the force direction will be changed during the deformation process, thereby transferring the deformation to the position of the resonant cavity 2211, and then transferring the deformation to the resonant film 212, so that stress is generated in the resonant film 212 and the piezoelectric component 100, thereby changing the structural resonant frequency. After the piezoelectric component 100 uses the inverse piezoelectric effect to stimulate the resonant film 212 to vibrate, the piezoelectric component 100 can simultaneously detect the pressure value through the positive piezoelectric effect to generate an electrical signal, and then analyze and judge the electrical signal through an external circuit, and use the electrical signal to infer the magnitude of the pressure to be measured.

[0138] The pressure sensitive film 2212 is placed at the position of the pressure chamber 223 so that the pressure applied by the outside can directly act on the pressure sensitive film 2212. When the pressure sensitive film 2212 is subjected to pressure, the pressure sensitive film 2212 will undergo a slight deformation, which will then be transmitted to the resonant structure 210 connected to the pressure sensitive film 2212, and then the pressure detection is achieved through the cooperation of the resonant cavity 2211, the resonant film 212 and the piezoelectric component 100.

[0139] The resonant structure 210 is connected to the pressure sensitive film 2212, so when the resonant structure 210 and the pressure sensitive film 2212 are deformed, a certain stress will be generated on the resonant film 212, causing the resonant frequency of the resonant structure 210 to change. This change can be captured by the piezoelectric component 100 and converted into an electrical signal, thereby achieving accurate measurement of pressure.

[0140] In the present application, the pressure detection can be realized by utilizing the forward and reverse piezoelectric effects of the piezoelectric film material in the piezoelectric component 100. The reverse piezoelectric effect can be used to reversely drive the resonance film 212 on the resonance structure 210 to vibrate, and the forward piezoelectric effect can be used to detect the frequency parameters of the resonance structure 210.

[0141] The arrangement of the pressure sensitive film 2212 combined with the resonant structure 210 also has many advantages. Since the pressure sensitive film 2212 can directly sense the change in the pressure to be measured, this arrangement has higher performance and accuracy. Furthermore, since the resonant structure 210 can produce a change in vibration frequency after being pressurized, this arrangement can effectively reduce the influence of interference signals and improve the accuracy of measurement. In addition, the above arrangement also has good stability and reliability, and can operate stably for a long time in harsh environments.

[0142] In practical applications, the arrangement of the pressure sensitive film 2212 combined with the resonant structure 210 is widely used in various fields. For example, in the field of industrial automation, the arrangement of the pressure sensitive film 2212 combined with the resonant structure 210 can be used to achieve precise pressure control and monitoring, and improve production efficiency and product quality. In automotive electronic systems, the arrangement of the pressure sensitive film 2212 combined with the resonant structure 210 can be used to monitor the pressure and temperature of the tire, thereby improving driving safety and comfort. In medical equipment, the arrangement of the pressure sensitive film 2212 combined with the resonant structure 210 can be used to monitor the patient's vital signs, such as blood pressure and heart rate.

[0143] The combination of the pressure sensitive film 2212 and the resonant structure 210 is an efficient, accurate and stable pressure sensing technology, which can improve the performance and accuracy of traditional pressure sensitive devices and provide better technical support for various application fields.

[0144] In some examples, the pressure sensitive structure 220 is formed by a SI wafer 300 , the resonant structure 210 is formed by a SOI wafer 400 , and the device layer 410 of the SOI wafer 400 is bonded to one side of the SI wafer 300 .

[0145] With the continuous advancement of semiconductor technology, the processing technology of the resonant structure 210 based on silicon on insulator (SOI) material is becoming increasingly mature. In the present application, a SOI wafer 400 and a SI wafer 300 can be used to process and form the main body of the piezoelectric resonant pressure sensor 10 (the rest of the piezoelectric component 100 and the cover 500), and the SOI wafer 400 and the SI wafer 300 are combined by bonding.

[0146] The SI wafer 300 can be processed to form a pressure sensitive structure 220. Advanced micro-machining techniques such as photolithography and etching are required. Different from the resonant structure 210, the pressure sensitive structure 220 usually has a more complex structure, such as a resonant cavity 2211, a pressure cavity 223, a pressure sensitive film 2212, etc., to achieve a sensitive response to external pressure. The resonant cavity 2211 can be opened in the device layer 410, the pressure cavity 223 can be opened in the substrate layer 430, and the pressure sensitive film 2212 can be a part of the device layer 410.

[0147] After the processing of the SOI wafer 400 is completed, the SOI wafer 400 and the SI wafer need to be bonded. During the bonding process, the device layer 410 of the SOI wafer 400 and the SI wafer 300 are closely attached together by precisely controlling the bonding conditions (such as temperature, pressure, time, etc.). The bonded resonant structure 210 not only retains the high performance characteristics of the resonant structure 210, but also realizes a sensitive response to external pressure, thereby improving the stability and reliability of the entire system.

[0148] It should be noted that the SOI material may be composed of a silicon film (corresponding to the device layer 410), a silicon dioxide buried layer (corresponding to the buried oxide layer 420) and a silicon substrate (corresponding to the substrate layer 430). This structure enables the SOI material to have unique properties in terms of mechanics, electricity and heat, and is very suitable for manufacturing a high-performance resonant structure 210.

[0149] Specifically, the SI wafer 300 is an integrated silicon crystal structure, the pressure chamber 223 and the resonance chamber 2211 are both opened on the SI wafer 300, and the SOI wafer 400 includes a device layer 410, a buried oxide layer 420 and a substrate layer 430. The thickness of the device layer 410 can be the same as the thickness of the resonance film 212, and the resonance film 212 is a part of the resonance structure 210. The corresponding resonance structure 210 is formed by removing the buried oxide layer 420 and the substrate layer 430 from the SOI wafer 400 and leaving the device layer 410 alone.

[0150] The resonance structure 210 of corresponding thickness can be processed on the SOI wafer 400 through precise micromachining technology. For example, the substrate layer 430 and the buried oxide layer 420 in the SOI wafer 400 can be cut off, and the device layer 410 can be used as the resonance structure 210. In the specific processing process, the substrate layer 430 and the buried oxide layer 420 can be bonded to the device layer 410, and then the substrate layer 430 and the buried oxide layer 420 can be cut off. This method can ensure the processing accuracy and reduce the process difficulty. When the SOI wafer 400 has the substrate layer 430 and the buried oxide layer 420, it can have sufficient thickness to facilitate bonding with the device layer 410.

[0151] The thickness of the device layer 410 in the SOI wafer 400 can be strictly controlled. The thickness of the device layer 410 can be set in advance to the thickness of the resonant structure 210. The resonant film 212 is a part of the resonant structure 210, so the thickness of the device layer 410 also corresponds to the thickness of the resonant film 212.

[0152] The SOI wafer 400 can be processed into a resonant structure 210 with a specific shape and size by using advanced photolithography, etching and other technologies.

[0153] During the bonding process with the device layer 410 , an oxide layer 230 is formed at the bonding location.

[0154] The above structure is the processing of SOI material. For example, this processing technology of the resonant structure 210 based on SOI material has many advantages. The high mechanical quality factor of SOI material makes the resonant structure 210 have lower mechanical loss and higher energy conversion efficiency. Secondly, the insulating buried layer of SOI material can effectively isolate the electrical interference between the device layer 410 and the substrate, thereby improving the stability of the system. In addition, the low thermal expansion coefficient and low stress characteristics of SOI material help to reduce the thermal drift and mechanical stress changes of the resonant structure 210 when the temperature changes, thereby improving the long-term stability of the system.

[0155] In some examples, at least one resonant cavity 2211 is provided, and in the direction of the resonant structure 210 away from the piezoelectric component 100 , the projection of at least one resonant cavity 2211 surrounds the outside of the projection of the pressure cavity 223 .

[0156] At least one resonant cavity 2211 may be arranged around the projection of the pressure cavity 223. When at least two resonant cavities 2211 are arranged, more detection points may be provided, thereby improving the accuracy and stability of the measurement. When the pressure changes, the resonant films 212 corresponding to different resonant cavities 2211 may produce corresponding resonant frequency changes, and these resonant films 212 may verify each other, thereby improving the accuracy of the measurement.

[0157] In some examples, at least one resonant cavity 2211 is opened on a side of the SI wafer 300 close to the SOI wafer 400 , and a pressure cavity 223 is opened on a side of the SI wafer 300 away from the SOI wafer 400 .

[0158] The above structure discloses a piezoelectric resonant pressure sensor 10 that combines an SI wafer 300 and an SOI wafer 400. This sensor has a unique design and powerful functions, and can accurately measure the specific value of the pressure to be measured.

[0159] When the pressure to be measured acts on the pressure sensitive structure 220, the pressure is first transmitted to the resonant film 212 through the anchor point 240. The resonant film 212 can deform when subjected to pressure. The pressure to be measured is converted into stress on the film during the process of being transmitted to the resonant film 212.

[0160] Next, the stress on the resonant film 212 is further transmitted to the piezoelectric component 100. The piezoelectric component 100 is a device that can convert mechanical stress into an electrical signal, and this conversion process is achieved by using the piezoelectric effect. During the transmission process, the pressure to be measured is again converted into stress on the piezoelectric component 100, thereby generating an electrical signal related to the pressure to be measured.

[0161] During the transmission of the pressure to be measured, the resonance film 212 will produce a resonance change. The piezoelectric component 100 uses the inverse piezoelectric effect to excite the resonance film 211 to vibrate, and uses the direct piezoelectric effect to detect the change in the resonance frequency of the resonance film 212, thereby detecting the value of the pressure to be measured. The inverse piezoelectric effect refers to the phenomenon that piezoelectric materials produce deformation under the action of an electric field. By applying an electric field, the piezoelectric component 100 can be stimulated to produce resonance, thereby further detecting the pressure to be measured.

[0162] In some examples, the sum of the opening depth of the resonance cavity 2211 and the opening depth of the pressure cavity 223 is less than the thickness of the SI wafer 300 .

[0163] The above arrangement can make the opening positions of the pressure chamber 223 and the resonance chamber 2211 in the SI wafer 300 staggered with each other, rather than being on the same horizontal line. The staggered position can be used as an anchor point 240 for transmitting stress, and the stress received on the pressure sensitive film 2212 can be better transmitted to the resonance film 212 through the anchor point 240. In the process of transmitting the pressure to be measured to the resonance component 200, the resonance frequency of the resonance film 212 in the resonance component 200 will change. The piezoelectric component 100 uses the inverse piezoelectric effect to excite the resonance film 212 to vibrate, and at the same time uses the positive piezoelectric effect to detect the change in the resonance frequency of the resonance film 212, thereby detecting the specific value of the pressure to be measured, ensuring that the piezoelectric detection is carried out normally, and making the accuracy of the piezoelectric detection more accurate.

[0164] In some examples, after the device layer 410 is bonded to the SI wafer 300 , the buried oxide layer 420 and the substrate layer 430 are removed from the SOI wafer 400 to form the resonant structure 210 . Furthermore, an oxide layer 230 is formed at the bonding position of the device layer 410 and the SI wafer 300 .

[0165] In some examples, a cover 500 is disposed on a side of the piezoelectric component 100 facing away from the resonant structure 210 , and the cover 500 and the piezoelectric component 100 form a sealed cavity; and / or,

[0166] A protection structure 600 is disposed on a side of the piezoelectric component 100 that is away from the resonant structure 210 . The protection structure 600 covers the surface of the piezoelectric component 100 .

[0167] The side of the piezoelectric component 100 that is away from the resonant structure 210 is provided with a cover 500. The cover 500 and the piezoelectric component 100 together enclose a sealed cavity, which can be set as a vacuum cavity or a cavity with a specific medium, such as nitrogen, ammonia, xenon, etc. This sealing structure ensures that the piezoelectric component 100 is not disturbed by the external environment during operation, such as dust, moisture or other impurities that may affect its performance. This setting not only extends the service life of the piezoelectric component 100, but also ensures the stability of its performance, thereby improving the reliability and durability of the entire piezoelectric resonant pressure sensor 10.

[0168] The pressure in the sealed cavity and the pressure in the pressure cavity 223 may have a certain pressure difference, and an absolute pressure or relative pressure sensor may be formed by calculating the absolute pressure difference or the relative pressure difference. Among them, the absolute pressure difference means that when the sealed cavity is a vacuum cavity, the pressure value in the sealed cavity is zero, and the detection value of the pressure cavity 223 by the piezoelectric resonant pressure sensor 10 is the pressure value received by the pressure cavity 223. At this time, the sensor is an absolute pressure sensor. The relative pressure difference means that the sealed cavity is a cavity with a specific pressure. At this time, there is a medium in the sealed cavity and the pressure is maintained at a certain value. The detection value of the pressure cavity 223 by the piezoelectric resonant pressure sensor 10 needs to be subtracted from the pressure value in the sealed cavity to obtain the pressure value received by the pressure cavity 223. At this time, the sensor is a relative pressure sensor.

[0169] In addition to the cover 500, some arrangements may also provide a protective structure 600 on the side of the piezoelectric component 100 that is away from the resonant structure 210. This protective structure 600 can cover the surface of the piezoelectric component 100 to provide additional protection for the piezoelectric component 100. This arrangement is mainly intended to cope with some extreme working environments, such as high temperature, high pressure or strong electromagnetic fields. Under these environments, the piezoelectric component 100 may be severely damaged, resulting in degradation of its performance or failure. The presence of the protective structure 600 can resist these adverse factors to a certain extent and protect the piezoelectric component 100 from damage. By reasonably selecting materials, the protective structure 600 can also have functions such as temperature compensation.

[0170] In general, both the cover 500 and the protective structure 600 are used to protect the piezoelectric component 100 and ensure that it can work stably and reliably in a harsh working environment. The cover 500 and the protective structure 600 may also be provided at the same time as needed.

[0171] The piezoelectric component 100 may include a first electrode layer 110, a piezoelectric layer 120 and a second electrode layer 130 from bottom to top. The second electrode layer 130 may be partially etched, leaving only a partial structure to match the first electrode layer 110. At least one first electrode structure 140 may penetrate the piezoelectric layer 120 and be connected to the first electrode layer 110, and the first electrode structure 140 is not in contact with the second electrode layer 130. The second electrode structure 150 may be connected to the second electrode layer 130.

[0172] When any of the second electrode structures 150 receives a voltage, stress is generated in the piezoelectric layer 120 based on the inverse piezoelectric effect of the piezoelectric layer 120. At this time, since the neutral layer of the piezoelectric layer 120 deviates from the geometric center position of the piezoelectric layer 120, the piezoelectric layer 120 will be deformed, and the deformation of the piezoelectric layer 120 drives the entire piezoelectric resonator to deform.

[0173] When an alternating voltage having the same resonant frequency as the piezoelectric resonator is applied to any second electrode structure 150, the entire structure will resonate, and the resonant frequency is:

[0174]

[0175] In the formula, f r is the resonant frequency, μ n are the constants set when solving the Bessel function, t is the thickness, r is the radius, E is the Young's modulus, ρ is the density, and δ is the Poisson's ratio.

[0176] When the pressure chamber 223 receives the pressure to be detected, the pressure sensitive film 2212 will be deformed and generate working stress under the action of the pressure to be detected. The anchor point 240 can transmit the deformation and working stress of the pressure sensitive film 2212 to the piezoelectric resonator, specifically to the piezoelectric layer 120. During the transmission process of the anchor point 240, the anchor point 240 can change the direction of action of the pressure to be detected, reduce the possibility of damage to the resonant film 212, and increase the measurement range of the piezoelectric resonant pressure sensor 10.

[0177] The piezoelectric resonator may be provided with at least two second electrode structures 150, and when one of the second electrode structures 150 drives the piezoelectric layer 120 to vibrate, the other second electrode structure 150 detects the vibration of the piezoelectric resonator. The second electrode structure 150 that receives the voltage may be a driving electrode, and the second electrode structure 150 that detects the vibration may be a detection electrode.

[0178] Due to the positive piezoelectric effect of the piezoelectric film material, the detection electrode will generate an electrical signal, which can be used to detect the resonant frequency of the piezoelectric resonator.

[0179] Assume that the working stress generated by the pressure to be detected on the piezoelectric resonator is σ, and the resonant frequency of the piezoelectric resonator is:

[0180]

[0181] From the above formula, it can be seen that the pressure value can be determined when the frequency change of the piezoelectric resonator is detected.

[0182] When the piezoelectric layer 120 is deformed, the portion of the piezoelectric layer 120 close to the resonant structure 210 is squeezed by the pressure to be detected, and the portion of the piezoelectric layer 120 away from the resonant structure 210 is stretched by the pressure to be detected. On the cross section of the piezoelectric layer 120, the transition layer between the stretched portion of the piezoelectric layer 120 and the squeezed portion of the piezoelectric layer 120, which is neither stretched nor compressed and has almost zero stress, is the above-mentioned neutral layer.

[0183] Compared with the resistance detection type piezoelectric sensor which needs to set up a Wheatstone bridge and the capacitance detection type pressure sensor which needs to set up a capacitance bridge, the piezoelectric resonant pressure sensor 10 provided in the example of the present application does not require the setting of an additional detection circuit, has a simpler structure, and has a lower manufacturing cost.

[0184] In some examples, the piezoelectric assembly includes at least one piezoelectric detection structure, which can be directly or indirectly connected to the external circuit, and one piezoelectric detection structure is arranged at a position corresponding to each resonant cavity. Each piezoelectric detection structure includes a group of second electrode structures 150 and at least one first electrode structure 140.

[0185] The shape and pattern of the piezoelectric detection structure corresponding to the surface of the piezoelectric component 100 can be set as needed. Figures 6 to 11 The schematic diagrams show five configurations of the piezoelectric component 100 facing away from the resonant component 200. The piezoelectric component 100 of the present application is not limited to the above five configurations.

[0186] in, Figure 6 It is a three-dimensional schematic diagram of a pressure-sensitive device (a combination of a piezoelectric component 100, a resonant structure 210, and a pressure-sensitive structure 220) before the lead electrodes and the oxide structure layer (protective structure 600) are deposited. Figure 7 For Figure 6 In the corresponding top view, the resonant cavity 2211 in this embodiment is a square cavity (a cavity with a cubic structure). In this figure, four groups of second electrode structures 150 are provided, and each group of second electrode structures 150 includes an excitation electrode (driving electrode) and a detection electrode. Each group of second electrode structures 150 corresponds to a resonant cavity 2211. Figure 6 and Figure 7 In the figure, four resonant cavities 2211 are used as an example for illustrative description. The present application may also set other numbers of resonant cavities 2211. Figure 8 The piezoelectric resonant pressure sensor 10 structure with a circular cavity (a cylindrical cavity) is shown in FIG. Figure 6 similar.

[0187] Fig. 9 FIG. 2 shows the structure of a piezoelectric resonant pressure sensor 10 having a circular ring cavity. Fig.10 2 shows the structure of a piezoelectric resonant pressure sensor 10 having a beam structure. Fig.11 , a piezoelectric resonant pressure sensor 10 having a beam structure and a stress concentration structure is shown.

[0188] Reference Fig.12 and Fig.13 In a second aspect, the present application provides a pressure compensation system for a piezoelectric resonant pressure sensor 10, comprising:

[0189] At least one piezoelectric resonant pressure sensor 10 as described above; and

[0190] At least one compensation sensor 20, the compensation sensor 20 and the piezoelectric resonant pressure sensor 10 are spaced apart or integrally arranged;

[0191] The compensation sensor 20 can receive interference factors caused by environmental influences, and the piezoelectric resonant pressure sensor 10 can receive the pressure to be measured and the environmental pressure. The value of the pressure to be measured can be obtained by subtracting the detection value of the compensation sensor 20 from the detection value of the piezoelectric resonant pressure sensor 10.

[0192] The compensation sensor 20 will be affected by the environment, and the piezoelectric resonant pressure sensor 10 can receive the pressure to be measured and will also be affected by the same environment. The detection value of the piezoelectric resonant pressure sensor 10 minus the detection value of the compensation sensor 20 can obtain the value of the pressure to be measured.

[0193] In order to achieve the goal of accurately measuring pressure, a piezoelectric resonant pressure sensor 10 with higher accuracy is provided, which can accurately capture and measure pressure changes in various environments. However, environmental factors themselves may interfere with the sensor, resulting in deviations in the measurement results. In order to solve this problem, the present application proposes a pressure compensation system, which eliminates the interference of environmental influences on the measurement results by introducing a compensation sensor 20.

[0194] The pressure compensation system mainly includes two key parts: a piezoelectric resonant pressure sensor 10 and at least one compensation sensor 20. The piezoelectric resonant pressure sensor 10 is responsible for receiving the pressure to be measured. The piezoelectric resonant pressure sensor 10 will simultaneously detect the sum of the value of the pressure to be measured and the interference value of the surrounding environment. The compensation sensor 20 can be specifically responsible for detecting the interference value after being affected by the environment, that is, the atmospheric pressure around the sensor or other external pressure that may affect the measurement result. The corresponding value detected by the compensation sensor 20 is the value affected by the surrounding environment. The above-mentioned environmental influencing factors include but are not limited to interference factors such as temperature and vibration.

[0195] In order to accurately measure the target pressure, the value of the pressure to be measured can be obtained by subtracting the value of the pressure to be measured from the value of the pressure to be measured from the value of the pressure to be measured, thereby obtaining an accurate value of the pressure to be measured.

[0196] The above two sensors can be set in two ways: interval setting or integrated setting. In the interval setting, the piezoelectric resonant pressure sensor 10 and the compensation sensor 20 are placed in different positions to ensure that the two sensors receive corresponding pressures respectively. For example, the piezoelectric resonant pressure sensor 10 can measure the addition value (the directions of the two forces are the same) or subtraction value (the directions of the two forces are opposite) of the pressure value to be measured and the environmental interference value. The pressure value to be measured and the environmental interference value are both detections of the sensor in a specific direction, and the direction of the force is generally the same or opposite. The compensation sensor 20 can measure the interference value of the environmental influence alone. This setting method can obtain a more accurate pressure value to be measured through simple calculations.

[0197] In an integrated setup, the two sensors are integrated into the same device. This setup can make the environmental influences on the two sensors more consistent, further improving measurement accuracy.

[0198] Regardless of the setting method, the measurement data of the piezoelectric resonant pressure sensor 10 and the compensation sensor 20 will be sent to a processing unit. Taking the example that the piezoelectric resonant pressure sensor 10 can measure the sum of the pressure value to be measured and the environmental interference value, in this processing unit, the detection value of the piezoelectric resonant pressure sensor 10 will be subtracted from the detection value of the compensation sensor 20, so as to obtain the accurate pressure value to be measured. In this way, the compensation system can eliminate the influence of environmental influence on the measurement results and improve the accuracy and reliability of the measurement.

[0199] It is worth noting that the above pressure compensation system is not only applicable to static pressure measurement, but also to dynamic pressure measurement. For example, in the field of aerospace, an aircraft will experience various complex airflow pressure and temperature changes during flight. This pressure compensation system can ensure that the piezoelectric resonant pressure sensor 10 on the aircraft can accurately measure the internal pressure, thereby providing important protection for flight safety.

[0200] The pressure compensation system also has a wide range of application prospects. In the medical field, the pressure compensation system can be used to monitor the patient's blood pressure, intracranial pressure and other physiological parameters, providing an important basis for diagnosis and treatment. In the field of environmental monitoring, the pressure compensation system can be used to measure environmental parameters such as atmospheric pressure and underwater pressure, providing data support for environmental protection and climate change research.

[0201] In a third aspect, the present application provides a method for preparing a piezoelectric resonant pressure sensor 10, which is applicable to the above-mentioned piezoelectric resonant pressure sensor 10; the following processing method can be completed by MEMS processing equipment. The method is used to process the SI wafer 300 and the SOI wafer 400 into the piezoelectric resonant pressure sensor 10, and the method includes:

[0202] Step S100: Take the SI wafer 300 and open at least one resonant cavity 2211 on one side of the SI wafer 300;

[0203] The above steps can utilize advanced micro-nano processing technology to open at least one resonant cavity 2211 on the SI wafer 300.

[0204] Step S200: Take the SOI wafer 400 and set the thickness of the device layer 410 of the SOI wafer 400 to be the thickness of the resonant film 212;

[0205] The above steps can set the thickness of the device layer 410 to the ideal thickness of the resonant film 212. This step ensures that the resonant film has sufficient flexibility and mechanical strength to meet the working requirements of the piezoelectric resonant pressure sensor 10.

[0206] Step S300: turning over the SOI wafer 400 and bonding the device layer 410 to the side of the SI wafer 300 having the resonant cavity 2211;

[0207] The above steps can bond the device layer 410 to the SI wafer 300. This step utilizes the unique structure and excellent material properties of the SOI wafer 400 to achieve a stable connection of the device layer 410.

[0208] Step S400: thinning the SOI wafer 400, and removing the substrate layer 430 and the buried oxide layer 420 during the thinning process;

[0209] The above steps can successfully remove the substrate layer 430 and the buried oxide layer 420 by precisely controlling the thinning process, so that the SOI wafer 400 only retains the device layer 410. This step not only simplifies the structure of the sensor, but also improves its sensitivity. Part of the structure of the device layer 410 can be used as a resonant film 212 that can cooperate with the resonant cavity 2211.

[0210] Step S500: processing the piezoelectric component 100 on a side of the device layer 410 away from the device layer 410 , and reserving an external conductive structure on the piezoelectric component 100 ;

[0211] The above steps can process the piezoelectric component 100 on the side of the device layer 410 away from the SI wafer 300. The existence of the piezoelectric component 100 is the key to realize the conversion of the sensor electrical signal. At the same time, an external conductive structure can be reserved on the piezoelectric component 100 to connect the output signal of the sensor to the external circuit.

[0212] Step S600 : opening a pressure chamber 223 on a side of the SI wafer 300 away from the device layer 410 .

[0213] The above steps can realize the opening of the pressure chamber 223, and then the cover 500 can be set as needed.

[0214] Reference Figures 15 to 34 Schematic diagram of the preparation process of the piezoelectric resonant pressure sensor 10 is shown in FIG.

[0215] Fig.15 The original structure of the SI wafer 300 before processing is shown. As the processing flow progresses, a resonant cavity 2211 is opened on the wafer to form a specific resonant structure 210. Fig.16 As shown, the opening of the resonant cavity 2211 causes a significant change in the wafer structure, providing a basis for subsequent processing steps.

[0216] Fig.17 4 shows a schematic structural diagram of an unprocessed SOI wafer 400; Fig.18The schematic diagram shows the structure when the SOI wafer 400 is inverted and bonded toward the SI wafer 300 .

[0217] During the processing of the SOI wafer 400. Fig.17 As shown in FIG. 4 , the SOI wafer 400 also has a complete three-layer structure. As the process progresses, the wafer will be turned upside down and bonded toward the SI wafer 300. Fig.18 This step requires high-precision process control to ensure that the two wafers are accurately aligned and firmly bonded.

[0218] Fig.19 It shows a schematic structural diagram of an SOI wafer 400 that is inverted and bonded to an SI wafer 300; Fig. 20 It shows a schematic structural diagram after the SOI wafer 400 is bonded to the SI wafer 300 and the buried oxide layer 420 and the substrate layer 430 are removed.

[0219] After bonding, a composite structure consisting of an SI wafer 300 and an SOI wafer 400 is obtained. In order to further optimize its performance, the buried oxide layer 420 and the substrate layer 430 need to be removed. Fig. 20 This step allows the device layer 410 to directly contact the SI wafer 300, thereby improving the electrical performance of the overall structure.

[0220] Fig.21 The schematic diagram shows the structure after the piezoelectric component 100100 is deposited on the side of the device layer 410 away from the SI wafer 300; the piezoelectric component 100 is deposited on the side of the second device layer 410 away from the SI wafer 300. The piezoelectric component 100 is the core component of the piezoelectric resonant pressure sensor 10, and its performance directly determines the accuracy and stability of the sensor.

[0221] Fig. 22 It shows a schematic diagram of the structure after the piezoelectric component 100 is deposited on the side of the device layer 410 facing away from the SI wafer 300 and the second electrode layer 130 is etched;

[0222] After the piezoelectric component 100 is deposited, the second electrode layer 130 needs to be etched to form a specific electrode structure. Fig. 22 As shown, the etched electrode structure can be more effectively electrically connected to the piezoelectric component 100, thereby improving the response speed and sensitivity of the sensor.

[0223] Fig.23 It shows a structural schematic diagram when a protective structure 600 is arranged outside the piezoelectric component 100;

[0224] Fig.24 The protective structure 600 is set outside the piezoelectric component 100 and the viewing angle is switched to the Figure 3Schematic diagram of the structure in the middle BB direction;

[0225] In order to protect the piezoelectric component 100 from the influence of the external environment, a protective structure 600 needs to be arranged outside the piezoelectric component 100. The protective structure 600 is usually made of insulating material, which can effectively isolate external impurities such as moisture and dust, thereby extending the service life of the sensor. Fig.23 and Fig.24 As shown, the provision of the protection structure 600 makes the entire sensor structure more stable and reliable.

[0226] Fig.25 It is a structural schematic diagram of a piezoelectric component 100 in an example of the present application when a communication channel is opened on the second electrode layer 130; Fig.26 It is a structural schematic diagram of a piezoelectric component 100 in an example of the present application when a communication channel is opened on the first electrode layer 110; Fig. 27 This is a schematic structural diagram of a piezoelectric component 100 in an example of the present application, in which a top layer of metal is deposited after connecting channels are respectively opened on the first electrode layer 110 and the second electrode layer 130; Fig.28 A schematic diagram of the structure of the piezoelectric component 100 after patterning the top metal layer;

[0227] In order to improve the performance and convenience of the sensor, it is also necessary to open communication channels on the first electrode layer 110 and the second electrode layer 130 of the piezoelectric component 100, and deposit a top layer of metal. This step enables the sensor to connect and communicate with the external circuit more conveniently, thereby realizing real-time monitoring and data processing of the pressure signal. Fig.25 , Fig.26 , Fig. 27 and Fig.28 As shown, after this series of processing steps, a complete and powerful piezoelectric resonant pressure sensor 10 can be obtained.

[0228] Fig.29 The protective structure 600 is set outside the piezoelectric component 100 and the viewing angle is switched to the Figure 3 Schematic diagram of the structure in the AA direction; Fig.30 The schematic diagram shows the structure of the resonant structure 210 after the pressure chamber 223 is opened on the side away from the piezoelectric component 100; Fig.31 shows a schematic structural diagram of the cover 500 before processing; Fig.32 shows a schematic structural diagram of the cover 500 after being formed; Fig.33 The schematic diagram of the structure after the cover 500 is installed is shown. The cover 500 is fixed on the piezoelectric component 100 by bonding, and the bonding method can be anodic bonding, or metal bonding such as Al-Ge, Au-Au, or other bonding methods.

[0229] In order to further optimize the performance and use effect of the sensor, a pressure chamber 223 may be provided on the side of the resonant structure 210 away from the piezoelectric component 100, and a cover 500 may be provided outside the sensor to protect the internal structure from the influence of the external environment. Fig.30 , Fig.31 , Fig.32 and Fig.33 As shown, the addition of these additional structures makes the sensor have better stability and reliability in practical applications and can withstand more stable external pressure.

[0230] Fig.34 It shows a schematic structural diagram of a piezoelectric resonant pressure sensor 10 provided with a cover 500 but without a protective structure 600.

[0231] The manufacturing process of the piezoelectric resonant pressure sensor 10 involves multiple complex processing steps and precise process control. The processing of the piezoelectric resonant pressure sensor 10 can be completed by processing the SOI wafer 400, depositing the piezoelectric component 100, etching the electrode structure, and setting the protection structure 600 and the cover 500.

[0232] The same or similar numbers in the drawings of this application correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0233] The above are only preferred examples of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A piezoelectric resonant pressure sensor, characterized in that: Applied to the core electronics industry, the piezoelectric resonant pressure sensor comprises: A piezoelectric component is directly or indirectly connected to an external circuit; A resonant structure connected to the piezoelectric component, wherein the resonant structure has a resonant film; A pressure sensitive structure is arranged on a side of the resonant film away from the piezoelectric component; At least one resonance cavity is formed on a side of the pressure sensitive structure close to the resonance film, and the resonance film closes or does not close at least a part of the resonance cavity. A pressure cavity is formed on a side of the pressure sensitive structure away from the resonance film, and the pressure received by the pressure cavity can be transmitted to the resonance film on the resonance structure. In a direction of the pressure sensitive structure toward the piezoelectric component, a projection of at least one of the resonant cavities is outside a projection of the pressure cavity.

2. The piezoelectric resonant pressure sensor according to claim 1, characterized in that: The pressure sensitive structure comprises: A pressure sensitive portion is provided on a side of the resonant structure away from the piezoelectric component, and at least one of the resonant cavities is provided in the pressure sensitive portion; A pressure receiving part, which is integrally provided with the pressure sensitive part, the pressure receiving part is provided at a side of the pressure sensitive part away from the resonant structure, and the pressure chamber is opened in the pressure receiving part; A pressure-sensitive film is disposed in the middle of the pressure-sensitive portion, one side of the pressure-sensitive film is located in the pressure chamber, and the external pressure received by the pressure chamber acts on the pressure-sensitive film.

3. The piezoelectric resonant pressure sensor according to claim 2, characterized in that: The pressure sensitive structure is formed by processing an SI wafer, and the resonant structure is formed by processing an SOI wafer. The device layer of the SOI wafer is bonded to one side of the SI wafer.

4. The piezoelectric resonant pressure sensor according to claim 3, characterized in that: At least one resonant cavity is provided on a side of the SI wafer close to the SOI wafer, and a pressure cavity is provided on a side of the SI wafer away from the SOI wafer.

5. The piezoelectric resonant pressure sensor according to claim 4, characterized in that: The sum of the opening depth of the resonance cavity and the opening depth of the pressure cavity is less than the thickness of the SI wafer.

6. The piezoelectric resonant pressure sensor according to claim 3, characterized in that: After the device layer is bonded to the SI wafer, the buried oxide layer and the substrate layer are removed from the SOI wafer to form the resonant structure.

7. The piezoelectric resonant pressure sensor according to claim 3, characterized in that: An oxide layer is formed at the bonding position between the device layer and the SI wafer.

8. The piezoelectric resonant pressure sensor according to claim 1, wherein: A cover is provided on the side of the piezoelectric component away from the resonant structure, and the cover and the piezoelectric component enclose a sealed cavity; and / or, A protection structure is arranged on a side of the piezoelectric component away from the resonant structure, and the protection structure covers the surface of the piezoelectric component.

9. A pressure compensation system for a piezoelectric resonant pressure sensor, characterized in that: include: At least one piezoelectric resonant pressure sensor according to any one of claims 1 to 8; as well as, At least one compensation sensor, wherein the compensation sensor is spaced apart from or integrated with the piezoelectric resonant pressure sensor; The compensation sensor can receive ambient pressure, and the piezoelectric resonant pressure sensor can receive the pressure to be measured and the ambient pressure. The value of the pressure to be measured can be obtained by subtracting the detection value of the compensation sensor from the detection value of the piezoelectric resonant pressure sensor.

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