A MEMS vibration sensor module

Abstract

The application provides a MEMS vibration sensor module, which comprises a substrate, a circuit module, a bonding layer and a MEMS chip, the MEMS chip comprises an electrode, a center support column, a mass block, a plurality of piezoelectric cantilever beams, a plurality of surface acoustic wave vibration resonators and electrical leads, the mass block is arranged around the center support column, the plurality of piezoelectric cantilever beams are symmetrically arranged around the center support column, one end of each piezoelectric cantilever beam is connected to the center support column, the other end is connected to the mass block, and one surface acoustic wave vibration resonator is arranged at each end of each piezoelectric cantilever beam facing the surface of the substrate. The MEMS vibration sensor module of the application effectively isolates the heat stress transmission between the substrate and the piezoelectric cantilever beam by suspending the MEMS chip above the substrate as a whole, avoids the interference of the frequency drift detection caused by the thermal stress due to the temperature change, and further improves the detection accuracy by performing differential operation on the reverse frequency drift generated by the vibration resonators at both ends of each piezoelectric cantilever beam.

Description

Technical Field

[0001] This invention belongs to the field of microelectromechanical systems (MEMS) technology and relates to a MEMS vibration sensor module. Background Technology

[0002] In modern industry and scientific research, vibration monitoring is a core technology for ensuring equipment safety and enabling fault diagnosis and predictive maintenance. As a key sensor in the monitoring system, the performance of vibration sensors directly affects the accuracy and reliability of the monitoring results.

[0003] Based on their working principle, vibration sensors can be mainly classified into piezoelectric and capacitive types. Among them, piezoelectric vibration sensors are widely used due to their comprehensive advantages in sensitivity, frequency range, noise performance, and high-temperature resistance. However, traditional piezoelectric vibration sensors typically consist of discrete mass blocks, piezoelectric sensitive elements (such as quartz crystals or piezoelectric ceramics), and a base, resulting in large size, heavy weight, and poor economic efficiency for small-batch applications.

[0004] With the development of Micro-Electro-Mechanical Systems (MEMS) technology, vibration sensors have become miniaturized, integrated, and cost-effective, making them a current research hotspot. Piezoelectric MEMS vibration sensors are mainly divided into direct measurement and indirect measurement types. Direct measurement piezoelectric MEMS vibration sensors sense vibration signals by detecting the charge signals generated by piezoelectric materials. Their readout circuits are simple, but they are susceptible to charge leakage and integration drift at low frequencies, leading to signal distortion. In contrast, indirect measurement piezoelectric MEMS vibration sensors, especially those based on surface acoustic wave (SAW) resonators and their frequency drift characteristics, avoid the charge leakage problem in principle, enabling stable and accurate measurement of low-frequency vibration signals.

[0005] However, this type of surface acoustic wave (SAW) MEMS vibration sensor still faces significant challenges. Its sensor structure typically integrates multiple materials (such as piezoelectric layers, support layers, and electrodes), each with different coefficients of thermal expansion. When the ambient temperature changes, the resulting thermal stress mismatch causes the piezoelectric layer to produce non-ideal additional strain. This strain is detected by the SAW resonator, leading to a drift in the resonant frequency. This frequency drift caused by thermal stress is intertwined with the frequency drift caused by acceleration signals, severely interfering with the accuracy of the detection results and limiting the application of the vibration sensor in environments with fluctuating temperatures.

[0006] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a MEMS vibration sensor module to solve the problem of low measurement accuracy of MEMS vibration sensor modules in temperature fluctuation environments.

[0008] To achieve the above and other related objectives, the present invention provides a MEMS vibration sensor module, comprising:

[0009] substrate;

[0010] A circuit module connected to the substrate, the circuit module including a vibration frequency drift detection circuit and a differential output circuit;

[0011] A bonding layer is located on the surface of a predetermined area of ​​the substrate;

[0012] A MEMS chip includes electrodes, a central support pillar, a mass block, multiple piezoelectric cantilever beams, multiple surface acoustic wave (SAW) resonators, and electrical leads. The electrodes are located on the bonding layer and electrically connected to the circuit module. The central support pillar is located on the electrodes. The mass block is arranged around the central support pillar. The multiple piezoelectric cantilever beams are arranged symmetrically and at equal intervals around the central support pillar in a plane parallel to the substrate. One end of each piezoelectric cantilever beam is connected to the central support pillar, and the other end is connected to the mass block. The end of the mass block facing away from the piezoelectric cantilever beam is a free end. Each piezoelectric cantilever beam has a SAW resonator at each end facing the surface of the substrate. The SAW resonators are electrically connected to the electrodes through the electrical leads.

[0013] Optionally, the MEMS vibration sensor module further includes a temperature sensor integrated on the substrate. The temperature sensor is electrically connected to the circuit module and is used for in-situ temperature monitoring and to provide temperature compensation for signal processing of the circuit module.

[0014] Optionally, the temperature sensor includes one of a thermocouple, a thermistor, a resistance temperature detector, an integrated circuit temperature sensor, an infrared temperature sensor, a fiber optic temperature sensor, and a surface acoustic wave temperature sensor.

[0015] Optionally, the surface acoustic wave (SAW) resonators disposed at both ends of each piezoelectric cantilever beam are identical, and the SAW resonators are single-ended or double-ended resonators, and the reflection structure in the SAW resonators is a periodic electrode array or a phononic crystal.

[0016] Optionally, the electrode includes a plurality of spaced sub-electrodes, each sub-electrode corresponding to a plurality of piezoelectric cantilever beams, and each surface acoustic wave resonator located at both ends of each piezoelectric cantilever beam is electrically connected to the sub-electrode corresponding to the piezoelectric cantilever beam.

[0017] Optionally, the mass block is in the form of a circular annular cylinder, and the central support column is in the form of a cylinder.

[0018] Optionally, the width of the piezoelectric cantilever beam at its middle section is greater than the width of the two ends of the piezoelectric cantilever beam.

[0019] Optionally, the piezoelectric cantilever beam includes a supporting cantilever layer and a piezoelectric layer, wherein the piezoelectric layer is disposed on the side of the supporting cantilever beam layer facing the substrate.

[0020] Optionally, the material of the piezoelectric layer includes at least one of aluminum nitride, lithium niobate, lead zirconate titanate, and lithium tantalate, the thickness of the piezoelectric cantilever beam is in the range of 10 to 100 micrometers, and the thickness of the piezoelectric layer is in the range of 0.1 to 10 micrometers.

[0021] Optionally, the piezoelectric cantilever beam, the mass block, the central support column, the surface acoustic wave resonator, the electrode, and the electrical leads are integrally formed.

[0022] As described above, the MEMS vibration sensor module of the present invention includes a substrate, a circuit module, a bonding layer, and a MEMS chip. The circuit module is connected to the substrate and includes a vibration frequency drift detection circuit and a differential output circuit. The bonding layer is located on the surface of a predetermined area of ​​the substrate. The MEMS chip includes electrodes, a central support pillar, a mass block, multiple piezoelectric cantilever beams, multiple surface acoustic wave (SAW) resonators, and electrical leads. The electrodes are located on the bonding layer and electrically connected to the circuit module. The central support pillar is located on the electrodes. The mass block is arranged around the central support pillar. The multiple piezoelectric cantilever beams are symmetrically arranged with the central support pillar as the center and are equally spaced in a plane parallel to the substrate. One end of each piezoelectric cantilever beam is connected to the central support pillar, and the other end is connected to the mass block. Each piezoelectric cantilever beam has a SAW resonator at each end facing the surface of the substrate. The SAW resonators are electrically connected to the electrodes through electrical leads. The MEMS vibration sensor module of this invention features a MEMS chip suspended above a substrate to effectively isolate thermal stress transmission between the substrate and a piezoelectric cantilever beam. The piezoelectric cantilever beam employs a "single-end fixed support" design to release its own generated thermal stress, thereby avoiding frequency drift detection interference caused by thermal stress due to temperature changes. By placing identical vibration resonators at both ends of each piezoelectric cantilever beam to generate reverse frequency drift signals, differential operations can be performed to achieve sensitivity multiplication and common-mode noise suppression. Symmetrically arranging multiple piezoelectric cantilever beams enhances resistance to lateral interference. Integrating a temperature sensor for temperature monitoring and compensation further optimizes measurement accuracy across the entire temperature range. Moreover, this vibration sensor combines the advantages of MEMS technology—miniaturization, mass production capability, and low cost—making it highly valuable for industrial applications. Attached Figure Description

[0023] Figure 1 The diagram shown is a structural schematic of a MEMS vibration sensor module according to an embodiment of the present invention.

[0024] Figure 2 and Figure 3 The diagrams show the structural schematics of the MEMS chip in the MEMS vibration sensor module of the present invention in different embodiments.

[0025] Figure 4 and Figure 5 The diagrams shown are schematic representations of the surface acoustic wave resonator in the MEMS vibration sensor module of the present invention in different embodiments.

[0026] Figure 6 and Figure 7 The diagrams shown are schematic representations of the reflection structure in the surface acoustic wave resonator of the MEMS vibration sensor module of the present invention in different embodiments.

[0027] Figure 8The diagram shows the electrical connections of the surface acoustic wave resonator in the MEMS vibration sensor module of this invention.

[0028] Figure 9 The graph shows the frequency drift-acceleration characteristics of the MEMS vibration sensor module when the simulated acceleration range is 0~100g.

[0029] Figure 10 The graph shows the frequency drift-acceleration characteristics of a MEMS vibration sensor module when an acceleration of 1g is applied along the XY plane.

[0030] Explanation of reference numerals in the attached figures

[0031] 1 substrate 2 Circuit module 3 Bonding layer 4 MEMS chip 41 electrode 411 Sub-electrode 42 Central support column 43 mass block 44 piezoelectric cantilever beam 45 Surface acoustic wave resonator 46 Electrical leads 5 Temperature sensor Detailed Implementation

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components.

[0034] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0035] In the detailed description of embodiments of the present invention, for ease of explanation, the schematic diagrams illustrating the device structure may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0036] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0037] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0038] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0039] This invention provides a MEMS vibration sensor module. The MEMS vibration sensor module features high-temperature stability and resistance to lateral interference, enabling it to accurately detect acceleration signals in complex and variable application scenarios.

[0040] Please see Figure 1 The diagram shows a schematic of the structure of a MEMS vibration sensor module of the present invention in one embodiment, including a substrate 1, a circuit module 2, a bonding layer 3 and a MEMS chip 4. The circuit module 2 is connected to the substrate 1 and includes a vibration frequency drift detection circuit and a differential output circuit. The bonding layer 3 is located on the surface of a predetermined area of ​​the substrate 1.

[0041] Please see Figure 2 and Figure 3 The diagram shows a schematic representation of the MEMS chip 4 in a different embodiment of the MEMS vibration sensor module of the present invention, including an electrode 41, a central support column 42, a mass block 43, and multiple piezoelectric cantilever beams 44. Figure 2 Two of the piezoelectric cantilever beams 44 are shown in the example, with reference numeral 44 indicating one of the piezoelectric cantilever beams 44; Figure 3 The example shows four piezoelectric cantilever beams 44, with reference numeral 44 indicating one of the surface acoustic wave resonators 45, and multiple surface acoustic wave resonators 45 ( Figure 2 Four of the surface acoustic wave resonators 45 are shown in the example, with reference numeral 45 indicating one of the surface acoustic wave resonators 45. Figure 3The example shows eight surface acoustic wave (SAW) resonators 45 (reference numeral 45 indicates one of the SAW resonators 45) and electrical leads 46. The electrode 41 is located on the bonding layer 3 and electrically connected to the circuit module 2. The central support post 42 is located on the electrode 41. The mass block 43 is arranged around the central support post 42. A plurality of piezoelectric cantilever beams 44 are arranged symmetrically and at equal intervals with the central support post 42 as the center in a plane parallel to the substrate 1. One end of each piezoelectric cantilever beam 44 is connected to the central support post 42 and the other end is connected to the mass block 43. The end of the mass block 43 facing away from the piezoelectric cantilever beam 44 is a free end. Each piezoelectric cantilever beam 44 has one SAW resonator 45 at each end facing the surface of the substrate 1. The SAW resonators 45 are electrically connected to the electrode 41 through the electrical leads 46.

[0042] The MEMS vibration sensor module of this invention suspends the MEMS chip 4 entirely above the substrate 1 to effectively isolate the thermal stress transmission between the substrate 1 and the piezoelectric cantilever beam 44. The piezoelectric cantilever beam 44 adopts a "single-end fixed support" design to release its own thermal stress using the mass block 43 loaded at one end, thereby avoiding interference from thermal stress caused by temperature changes in frequency drift detection. By setting the same vibration resonator at both ends of each piezoelectric cantilever beam 44, the vibration resonators at both ends of the piezoelectric cantilever beam 44 generate a reverse frequency drift signal. Differential operation on the reverse frequency drift signal output can achieve sensitivity multiplication and common-mode noise suppression, thereby improving the detection accuracy of the sensor. By symmetrically arranging multiple piezoelectric cantilever beams 44 with the central support column 42 as the center, the anti-lateral interference capability is enhanced, which can further improve the detection accuracy of the sensor. By integrating a temperature sensor for in-situ temperature monitoring and compensation, the measurement accuracy across the entire temperature range is further optimized.

[0043] As an example, the substrate 1 provides mechanical damping and mechanical support for the MEMS chip 4. The substrate 1 is provided with electrical redistribution lines, which are used for collecting and conducting subsequent electrical signals.

[0044] As an example, the circuit module 2 is integrated on the substrate 1. The circuit module 2 includes a vibration frequency drift detection circuit and a differential output circuit.

[0045] As an example, the bonding layer 3 is located on the surface of a predetermined area of ​​the substrate 1, and the MEMS chip 4 is fixed to the substrate 1 through the bonding layer 3. The bonding layer 3 enables mechanical connection and electrical interconnection between the substrate 1 and the MEMS chip 4.

[0046] Specifically, the bonding layer 3 is only partially disposed between the MEMS chip 4 and the substrate 1, while no structure is disposed in the remaining areas. This allows the entire portion of the MEMS chip 4, except for the contact area with the bonding layer 3, to be suspended above the substrate 1. This cuts off the transmission path of thermal stress generated by the difference in thermal expansion coefficients of the substrate 1 to the MEMS chip 4, preventing the thermal stress generated by the substrate 1 from affecting the detection accuracy of the MEMS chip 4. This can significantly improve the stability and measurement accuracy at high temperatures.

[0047] In some embodiments, the bonding layer 3 is made of materials such as gold-aluminum, aluminum-germanium, and copper-tin.

[0048] As an example, the electrode 41 is located on and in contact with the bonding layer 3, and the electrode 41 is electrically connected to the circuit module 2 through the electrical redistribution line.

[0049] As an example, the central support column 42 is located on and in contact with the electrode 41. The central support column 42 connects and fixes the MEMS chip 4 and the substrate 1 to the bonding layer 3 via the electrode 41. The central support column 42 provides stable support for the piezoelectric cantilever beam 44, ensuring that the piezoelectric cantilever beam 44 can move and respond accurately when subjected to external acceleration.

[0050] As an example, the size of the bonding layer 3 in the XY plane is not greater than the size of the central support column 42 in the XY plane, so as to ensure that there is no bonding layer 3 between the piezoelectric cantilever beam 44 and the substrate 1, thereby better isolating the thermal stress transmission between the substrate 1 and the piezoelectric cantilever beam 44.

[0051] In some embodiments, the central support column 42 is cylindrical.

[0052] As an example, such as Figure 2 and Figure 3 The mass block 43 is arranged around the central support column 42, and is symmetrical about the central support column 42. A plurality of piezoelectric cantilever beams 44 are symmetrically distributed along the central support column 42 in a plane parallel to the substrate 1, and the combined structure of the piezoelectric cantilever beams 44 and the mass block 43 is symmetrically distributed about the central support column 42. The plurality of piezoelectric cantilever beams 44 are equally spaced, and the included angle between any two adjacent piezoelectric cantilever beams 44 is equal. One end of each piezoelectric cantilever beam 44 is fixedly connected to the side wall of the central support column 42 near the substrate 1, and the other end is connected to the inner wall of the mass block 43. The end of the mass block 43 facing away from the piezoelectric cantilever beam 44 is freely disposed.

[0053] Specifically, the piezoelectric cantilever beam 44 is composed of multiple materials, each with different coefficients of thermal expansion. When the ambient temperature changes, the resulting thermal stress mismatch can cause non-ideal additional strain in the piezoelectric layer of the piezoelectric cantilever beam 44. To address this, each piezoelectric cantilever beam 44 adopts a "single-end fixed support" design, with one end fixed to the central support column 42 and the other end bearing the mass block 43. This allows the thermal stress generated by the piezoelectric cantilever beam 44 during temperature changes to be released through the mass block 43, thereby preventing the thermal stress caused by temperature changes from interfering with frequency drift detection.

[0054] As an example, the piezoelectric cantilever beam 44 includes a supporting cantilever layer (not shown) and a piezoelectric layer (not shown), the piezoelectric layer being disposed on the side of the supporting cantilever beam layer facing the substrate 1.

[0055] In some embodiments, the piezoelectric layer is made of at least one of aluminum nitride, lithium niobate, lead zirconate titanate, and lithium tantalate. For example, in one embodiment, the piezoelectric material used in the piezoelectric cantilever beam 44 is aluminum nitride.

[0056] In some embodiments, the thickness of the piezoelectric cantilever beam 44 is in the range of 10 to 100 micrometers, such as any value within this range, including 10 micrometers, 15 micrometers, 20 micrometers, 30 micrometers, 50 micrometers, 70 micrometers, 90 micrometers, 100 micrometers, etc.

[0057] In some embodiments, the thickness of the piezoelectric layer ranges from 0.1 to 10 micrometers, for example, any value within this range such as 0.1 micrometer, 0.5 micrometer, 1.5 micrometer, 2 micrometer, 4 micrometer, 7 micrometer, 9 micrometer, 10 micrometer, etc.

[0058] As an example, the strain concentration areas of the piezoelectric cantilever beam 44 are at both ends of the beam. The piezoelectric cantilever beam 44 is designed with a variable cross-section configuration that is narrow at both ends and wide in the middle. This design makes the width of the middle part of the piezoelectric cantilever beam 44 greater than the width of the two ends of the piezoelectric cantilever beam 44, thereby enabling greater strain to be obtained in the stress concentration area and improving the sensitivity of vibration detection.

[0059] In some embodiments, the width of the middle portion of the piezoelectric cantilever beam 44 is smaller than the width of both ends of the piezoelectric cantilever beam 44.

[0060] In some embodiments, the width of the middle portion of the piezoelectric cantilever beam 44 is equal to the width of both ends of the piezoelectric cantilever beam 44.

[0061] In some embodiments, the number of the piezoelectric cantilever beams 44 can be 2, 3, 4, ... n. For example, as... Figure 2The MEMS chip 4 shown includes two piezoelectric cantilever beams 44, with the included angle between adjacent piezoelectric cantilever beams 44 being 180 degrees; as shown Figure 3 The MEMS chip 4 shown includes four piezoelectric cantilever beams 44, and the included angle between adjacent piezoelectric cantilever beams 44 is 90 degrees.

[0062] As an example, the mass block 43 is a circular annular cylinder symmetrical about the central support column 42 (e.g., Figure 2 and Figure 3 As shown), each of the piezoelectric cantilever beams 44 is connected together and fixed at one end.

[0063] In some embodiments, the mass block 43 may also be a square ring cylinder, a pentagonal ring cylinder, or other polygonal ring cylinders.

[0064] As an example, a specific distance h is maintained between the lower surface of the mass block 43 and the upper surface of the substrate 1. The value of h can be achieved by adjusting the height of the bonding layer 3 on the substrate 1. The maximum displacement distance of the mass block 43 under the fracture strength of the piezoelectric cantilever beam 44 is D, and h is required to satisfy 0.8D ≤ h ≤ D. The specific distance h serves as a stop gap for vertical movement, ensuring normal movement range while providing reliable overload protection and improving the structural reliability of the device.

[0065] In an optional embodiment, the value of h is 10 micrometers. Considering factors such as the processing error, installation accuracy and margin of the mass block 43, the value of h can be set to 15 micrometers. In this case, the value of h is designed under the structure based on Si material.

[0066] As an example, the surface acoustic wave (SAW) resonators 45 are arranged in pairs at both ends of the surface of the piezoelectric layer of each piezoelectric cantilever beam 44, and are placed perpendicular to the principal strain direction of the piezoelectric cantilever beam 44. The signal terminal and ground terminal of each SAW resonator 45 are electrically connected to the electrode 41 through the electrical lead 46. The SAW resonators 45 arranged at both ends of each piezoelectric cantilever beam 44 are identical and have a consistent initial resonant frequency.

[0067] In some embodiments, the surface acoustic wave resonator 45 is a single-ended resonator (e.g., Figure 4 (as shown) or a two-terminal resonator (such as Figure 5 (As shown).

[0068] In some embodiments, the reflection structure in the surface acoustic wave resonator 45 employs a periodic electrode array (such as...). Figure 6 (as shown) or phononic crystal (such as) Figure 7 (As shown).

[0069] As an example, such as Figure 2 and Figure 3 As shown, the electrode 41 includes a plurality of spaced sub-electrodes 411 ( Figure 2 Two of the sub-electrodes 411 are shown in the example, with reference numeral 411 indicating one of the sub-electrodes 411; Figure 3 The example shows four sub-electrodes 411 (reference numeral 411 indicates one of the sub-electrodes 411). The number of sub-electrodes 411 is the same as the number of piezoelectric cantilever beams 44, and each sub-electrode 411 corresponds one-to-one with a piezoelectric cantilever beam 44. The electrical signals of the signal terminals and ground terminals of each surface acoustic wave resonator 45 located at both ends of each piezoelectric cantilever beam 44 are respectively connected to the sub-electrode 411 corresponding to the piezoelectric cantilever beam 44 through the electrode leads 46.

[0070] As an example, the various structures in the MEMS chip 4 (the piezoelectric cantilever beam 44, the mass block 43, the central support column 42, the surface acoustic wave resonator 45, the electrode 41, and the electrical lead 46) can be integrally formed using semiconductor micromachining technology.

[0071] Please see Figure 8 The diagram shows the electrical connections of the surface acoustic wave (SAW) resonator 45 in the MEMS vibration sensor module of this invention. When the MEMS vibration sensor module is in operation, external vibrations cause the mass block 43 to move, resulting in strain on the piezoelectric cantilever beam 44. The two SAW resonators 45 located at opposite ends of the same piezoelectric cantilever beam 44 detect resonant frequencies with opposite frequency shifts through oscillators, such as... Figure 4 The surface acoustic wave resonator 1 shown detects f0 + Δf a Surface wave resonator 2 detects f0 - Δf a The frequency drift 2Δf is achieved by sequentially passing the mixer and low-pass filter through them and then differentially amplifying the output. a .

[0072] Specifically, the piezoelectric cantilever beam 44 generates opposite strains when it senses vertical (Z-direction perpendicular to the plane of the piezoelectric cantilever beam 44) acceleration signals at the end near the central support column 42 and the end near the mass block 43. (See also...) Figure 9The simulation curves of frequency drift-acceleration characteristics of the MEMS vibration sensor module are shown in the simulation range of 0~100g acceleration. The two surface acoustic wave resonators 45 located at both ends of the same piezoelectric cantilever beam 44 generate a pair of frequency drifts in opposite directions in the Z direction. By performing differential operation on this pair of frequency drift signals, sensitivity can be multiplied and common-mode noise can be suppressed, thereby directly improving the detection accuracy of the vibration sensor for the Z-axis acceleration signal.

[0073] Furthermore, for any temperature-induced disturbance acceleration that may exist laterally (parallel to the XY plane where the piezoelectric cantilever beam 44 is located), weak, reverse-symmetrical strains are generated on the multiple piezoelectric cantilever beams 44 symmetrically distributed about the central support column 42. (See also...) Figure 10 The simulation curves of the frequency drift-acceleration characteristics of the MEMS vibration sensor module when an acceleration of 1g is applied along the XY plane are shown. The surface acoustic wave resonators 45 on the two symmetrical piezoelectric cantilever beams 44 induce equal and opposite frequency drifts. The superposition of the two signals can cancel out the transverse induced signal, enhance the anti-transverse interference capability of the MEMS vibration sensor module, and thus indirectly improve the detection accuracy of the vibration sensor for the Z-axis acceleration signal.

[0074] In some embodiments, to further avoid the impact of frequency drift caused by temperature changes on detection accuracy, a temperature sensor 5 can be further installed in the MEMS vibration sensor module. The temperature sensor 5 is used to monitor the temperature in real time, and a mathematical model or machine learning algorithm is used to predict the frequency drift caused by temperature changes. By subtracting the frequency drift caused by temperature changes from the total drift, the frequency drift caused by acceleration can be accurately obtained.

[0075] As an example, the temperature sensor 5 is integrated on the substrate 1 and is electrically connected to the circuit module 2 via the electrical rewiring. The temperature sensor 5 performs in-situ temperature monitoring of the operating environment, providing temperature compensation parameters for subsequent frequency drift signal processing by the circuit module, thereby further optimizing measurement accuracy across the entire temperature range.

[0076] In some embodiments, the temperature sensor 5 includes one of a thermocouple, a thermistor, a resistance temperature detector, an integrated circuit temperature sensor, an infrared temperature sensor, an optical fiber temperature sensor, and a surface acoustic wave temperature sensor.

[0077] The MEMS vibration sensor module provided by this invention can effectively reduce the impact of temperature changes on frequency drift, and has high precision, high stability and high reliability. At the same time, it has the advantages of MEMS technology miniaturization, mass production and low cost, and has high industrial application value.

[0078] In summary, the MEMS vibration sensor module of the present invention includes a substrate, a circuit module, a bonding layer, and a MEMS chip. The circuit module is connected to the substrate and includes a vibration frequency drift detection circuit and a differential output circuit. The bonding layer is located on the surface of a predetermined area of ​​the substrate. The MEMS chip includes electrodes, a central support pillar, a mass block, multiple piezoelectric cantilever beams, multiple surface acoustic wave (SAW) resonators, and electrical leads. The electrodes are located on the bonding layer and electrically connected to the circuit module. The central support pillar is located on the electrodes. The mass block is arranged around the central support pillar. The multiple piezoelectric cantilever beams are symmetrically arranged with the central support pillar as the center and are equally spaced in a plane parallel to the substrate. One end of each piezoelectric cantilever beam is connected to the central support pillar, and the other end is connected to the mass block. Each piezoelectric cantilever beam has a SAW resonator at each end facing the surface of the substrate. The SAW resonators are electrically connected to the electrodes through electrical leads. The MEMS vibration sensor module of this invention features a MEMS chip suspended above a substrate to effectively isolate thermal stress transmission between the substrate and a piezoelectric cantilever beam. The piezoelectric cantilever beam employs a "single-end fixed support" design to release its own generated thermal stress, thereby avoiding frequency drift detection interference caused by temperature changes. Identical vibration resonators are placed at both ends of each piezoelectric cantilever beam to generate reverse frequency drift signals. Differential operation outputs a signal that doubles sensitivity and suppresses common-mode noise. Symmetrical arrangement of multiple piezoelectric cantilever beams enhances resistance to lateral interference. Integrated temperature sensors provide temperature monitoring and compensation, further optimizing measurement accuracy across the entire temperature range. Furthermore, this vibration sensor combines the advantages of MEMS technology—miniaturization, mass production capability, and low cost—making it highly valuable for industrial applications. Therefore, this invention effectively overcomes the shortcomings of existing technologies and possesses significant industrial applicability.

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A MEMS vibration sensor module, characterized in that, include: substrate; A circuit module connected to the substrate, the circuit module including a vibration frequency drift detection circuit and a differential output circuit; A bonding layer is located on the surface of a predetermined area of ​​the substrate; A MEMS chip includes electrodes, a central support pillar, a mass block, multiple piezoelectric cantilever beams, multiple surface acoustic wave (SAW) resonators, and electrical leads. The electrodes are located on the bonding layer and electrically connected to the circuit module. The central support pillar is located on the electrodes. The mass block is arranged around the central support pillar. The multiple piezoelectric cantilever beams are arranged symmetrically and at equal intervals around the central support pillar in a plane parallel to the substrate. One end of each piezoelectric cantilever beam is connected to the central support pillar, and the other end is connected to the mass block. The end of the mass block facing away from the piezoelectric cantilever beam is a free end. Each piezoelectric cantilever beam has a SAW resonator at each end facing the surface of the substrate. The SAW resonators are electrically connected to the electrodes through the electrical leads.

2. The MEMS vibration sensor module according to claim 1, characterized in that: The MEMS vibration sensor module also includes a temperature sensor, which is integrated on the substrate and electrically connected to the circuit module. The temperature sensor is used for in-situ temperature monitoring and provides temperature compensation for signal processing of the circuit module.

3. The MEMS vibration sensor module according to claim 2, characterized in that: The temperature sensor includes one of the following: thermocouple, thermistor, resistance temperature detector, integrated circuit temperature sensor, infrared temperature sensor, fiber optic temperature sensor, and surface acoustic wave temperature sensor.

4. The MEMS vibration sensor module according to claim 1, characterized in that: The surface acoustic wave (SAW) resonators located at both ends of each piezoelectric cantilever beam are identical. The SAW resonators are either single-ended or double-ended, and the reflection structures in the SAW resonators are either periodic electrode arrays or phononic crystals.

5. The MEMS vibration sensor module according to claim 1, characterized in that: The electrode includes multiple spaced sub-electrodes, each sub-electrode corresponding to a multiple piezoelectric cantilever beam. Each surface acoustic wave resonator located at both ends of each piezoelectric cantilever beam is electrically connected to the corresponding sub-electrode of the piezoelectric cantilever beam.

6. The MEMS vibration sensor module according to claim 1, characterized in that: The mass block is in the shape of a circular annular cylinder, and the central support column is in the shape of a cylinder.

7. The MEMS vibration sensor module according to claim 1, characterized in that: The width of the piezoelectric cantilever beam at its middle section is greater than the width of the piezoelectric cantilever beam at both ends.

8. The MEMS vibration sensor module according to claim 1, characterized in that: The piezoelectric cantilever beam includes a supporting cantilever layer and a piezoelectric layer, wherein the piezoelectric layer is disposed on the side of the supporting cantilever beam layer facing the substrate.

9. The MEMS vibration sensor module according to claim 8, characterized in that: The material of the piezoelectric layer includes at least one of aluminum nitride, lithium niobate, lead zirconate titanate, and lithium tantalate. The thickness of the piezoelectric cantilever beam ranges from 10 to 100 micrometers, and the thickness of the piezoelectric layer ranges from 0.1 to 10 micrometers.

10. The MEMS vibration sensor module according to claim 1, characterized in that: The piezoelectric cantilever beam, the mass block, the central support column, the surface acoustic wave resonator, the electrode, and the electrical leads are integrally formed.

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