Low-stress MEMS resonant accelerometer

Abstract

The application discloses a low-stress MEMS resonant accelerometer, which is processed by using an SOG process, and is characterized in that: an upper layer is an accelerometer micro-mechanical sensitive structure made of monocrystalline silicon, which is used for sensing external acceleration, and gold is deposited on the upper layer as an electrode, which is used for inputting and outputting signals; a lower layer is a glass substrate, which is used for supporting the micro-mechanical sensitive structure of the upper layer. By symmetrically arranging anchor points for supporting the micro-mechanical sensitive structure and stress release rings, residual stress generated in the direction of a sensitive axis of a tuning fork resonator due to the mismatch of thermal expansion coefficients of materials in a processing process is reduced. A thermal deformation matching frame is arranged to reduce thermal stress generated on the tuning fork resonator due to the inconsistent expansion or shrinkage deformation of each part of the micro-mechanical sensitive structure in a working temperature change process. The application reduces the residual stress generated in the processing process and the thermal stress generated in the working environment change of the sensor, thereby reducing the influence of temperature on the output frequency of the resonator and improving the long-term stability of the output of the resonant accelerometer.

Description

Technical Field

[0001] This invention belongs to the field of microelectromechanical systems (MEMS) technology, and specifically relates to a low-stress MEMS resonant accelerometer. Background Technology

[0002] MEMS sensors can integrate various micromechanical sensing structures, microsensors, microactuators, and microelectronic devices onto a single silicon chip, enabling the measurement of environmental variables in fields such as mechanics, thermodynamics, optics, and chemistry while miniaturizing the device. Compared to traditional sensors, MEMS sensors also offer advantages such as small size, high precision, and low cost, playing a crucial role in consumer electronics, automotive engineering, medical devices, and aerospace. MEMS accelerometers were among the first commercially available sensors; they are a type of sensor capable of measuring physical quantities such as acceleration and vibration, and are widely used in process industries, aerospace equipment, and unmanned systems.

[0003] MEMS accelerometers based on the resonant principle represent the future direction of high-precision accelerometer development due to their advantages such as small size, low cost, high accuracy, and near-digital output. Currently, institutions such as Tsinghua University, Peking University, Nanjing University of Science and Technology, and Xi'an Jiaotong University have developed prototype MEMS accelerometers based on the resonant principle. However, because MEMS sensors require multi-layer bonding and involve various materials during fabrication, the differences in thermal expansion coefficients between these materials can cause residual stress in the bonded sensitive chip. Furthermore, changes in the sensor's operating temperature can lead to thermal mismatch within the structure. This thermal stress can cause severe zero-bias stability and temperature drift problems, affecting the sensor's temperature consistency and stability. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a low-stress MEMS resonant accelerometer. This addresses the technical problem of residual stress easily generated in the tuning fork resonator during the manufacturing process of existing MEMS resonant accelerometers due to the mismatch in the thermal expansion coefficients of the materials, thereby reducing thermal mismatch within the structure during operating temperature changes and reducing the temperature drift of the resonant accelerometer output.

[0005] The present invention adopts the following technical solution:

[0006] A low-stress MEMS resonant accelerometer includes:

[0007] Glass substrate;

[0008] A micromechanical sensing structure disposed on the glass substrate, wherein electrodes are deposited on the surface of the micromechanical sensing structure;

[0009] The micromechanical sensing structure includes:

[0010] Mass block;

[0011] A first tuning fork resonator and a second tuning fork resonator arranged symmetrically;

[0012] A micro-lever amplification mechanism connecting the mass block and the tuning fork resonator;

[0013] First support micro-spring, second support micro-spring, third support micro-spring, and fourth support micro-spring are respectively set at the four corners of the mass block;

[0014] The first, second, third, fourth, fifth, and sixth anchor points are symmetrically arranged to symmetrically support the micromechanical sensitive structure.

[0015] The first stress-absorbing ring, the second stress-absorbing ring, the third stress-absorbing ring, and the fourth stress-absorbing ring are used to reduce residual stress during processing.

[0016] The first thermal deformation matching frame, the second thermal deformation matching frame, and the third thermal deformation matching frame are used to reduce thermal stress caused by changes in operating temperature.

[0017] Among them, the first anchor point, the second anchor point, the third anchor point, the fourth anchor point, the fifth anchor point, and the sixth anchor point, and the first stress-absorbing ring, the second stress-absorbing ring, the third stress-absorbing ring, and the fourth stress-absorbing ring.

[0018] Preferably, the first tuning fork resonator and the second tuning fork resonator are arranged symmetrically about the sensitive axis to form a differential sensitive structure.

[0019] Preferably, the first thermal deformation matching frame and the second thermal deformation matching frame are respectively connected to the first support microspring, the second support microspring, the third support microspring, the fourth support microspring and the first anchor point, the third anchor point, the fourth anchor point and the sixth anchor point at their two ends, so as to match the thermal deformation of the two ends of the support microspring in the sensitive axis direction.

[0020] Preferably, the first tuning fork resonator and the second tuning fork resonator are located at the thermal expansion center of the device to reduce bonding residual stress.

[0021] Preferably, the first stress-absorbing ring, the second stress-absorbing ring, the third stress-absorbing ring, and the fourth stress-absorbing ring are flexible structures that connect the first thermal deformation matching frame, the third thermal deformation matching frame, and the first anchor point, the third anchor point, the fourth anchor point, and the sixth anchor point to absorb residual stress and enhance impact resistance.

[0022] Preferably, the first stress-absorbing ring, the second stress-absorbing ring, the third stress-absorbing ring, and the fourth stress-absorbing ring offset the difference in thermal expansion coefficients between the monocrystalline silicon and the glass substrate through deformation.

[0023] Preferably, the micro-lever amplification mechanism includes multiple sets of symmetrical first micro-lever amplification structures, second micro-lever amplification structures, third micro-lever amplification structures, and fourth micro-lever amplification structures. The endpoints of the first force input end, second force input end, third force input end, fourth force input end, first force output end, second force output end, third force output end, and fourth force output end of each micro-lever are located on the same horizontal line to eliminate frequency drift caused by inconsistent thermal deformation.

[0024] Preferably, the glass substrate and the micromechanical sensitive structure are bonded by SOG process, and the glass substrate is high borosilicate glass.

[0025] Preferably, the second thermal deformation matching frame connects the first fulcrum end, the second fulcrum end, the third fulcrum end, and the fourth fulcrum end of the micro lever to ensure that the thermal deformation of the fulcrum end, the force input end, and the force output end is synchronized.

[0026] Preferably, the overall structure is symmetrical about the X-axis and Y-axis, with the Y-axis being the sensitive axis.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] A low-stress MEMS resonant accelerometer reduces residual stress in the tuning fork resonator's sensitive axis caused by material thermal expansion coefficient mismatch during manufacturing through symmetrically arranged anchor points supporting the micromechanical sensing structure and stress relief rings. A thermal deformation matching frame is also incorporated to minimize thermal stress on the tuning fork resonator caused by inconsistent expansion displacement along the sensitive axis at the input and output ends of the micro-lever, the support spring and mass block, and the connection between the support spring and the anchor area during operating temperature changes. This reduces the overall impact of temperature on the resonator's output frequency and improves the temperature stability of the resonant accelerometer's output.

[0029] This application provides a low-stress MEMS resonant accelerometer and its micromechanical sensing structure. Through the symmetrical arrangement of stress absorption rings, thermal deformation matching frames and micro-lever amplification mechanisms, it effectively suppresses residual stress from processing and thermal stress caused by changes in operating temperature, significantly reduces the deterioration of sensor zero-bias stability and temperature drift, and has the advantages of improving temperature consistency and long-term stability.

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the following description of the relative embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of an accelerometer fabricated using SOG technology;

[0033] Figure 2 It is a low-stress MEMS resonant accelerometer;

[0034] Figure 3 This is a schematic diagram of a micro-lever amplification mechanism.

[0035] Wherein: 1. Glass substrate; 2. Micromechanical sensing structure; 3. Electrode; 2-1. Mass block; 2-2a. First tuning fork resonator; 2-2b. Second tuning fork resonator; 2-3a. First micro-lever amplification structure; 2-3a-1. First force input end; 2-3a-2. First fulcrum end; 2-3a-3. First force output end; 2-3b. Second micro-lever amplification structure; 2-3b-1. Second force input end; 2-3b-2. Second fulcrum end; 2-3b-3. Second force output end; 2-3c. Third micro-lever amplification structure; 2-3c-1. Third force input end; 2-3c-2. Third fulcrum end; 2-3c-3. Third force output end; 2-3d. Fourth micro-lever amplification structure; 2-3d -1. Fourth force input end; 2-3d-2. Fourth fulcrum end; 2-3d-3. Fourth force output end; 2-4a. First support micro-spring; 2-4b. Second support micro-spring; 2-4c. Third support micro-spring; 2-4d. Fourth support micro-spring; 2-5a. First thermal deformation matching frame; 2-5b. Second thermal deformation matching frame; 2-5c. Third thermal deformation matching frame; 2-6a. First stress absorption ring; 2-6b. Second stress absorption ring; 2-6c. Third stress absorption ring; 2-6d. Fourth stress absorption ring; 2-7a. First anchor point; 2-7b. Second anchor point; 2-7c. Third anchor point; 2-7d. Fourth anchor point; 2-7e. Fifth anchor point; 2-7f. Sixth anchor point. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," and "one side," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0040] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0041] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0042] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0043] This invention provides a low-stress MEMS resonant accelerometer. By symmetrically arranging anchor points supporting the micromechanical sensing structure and using stress relief rings, it reduces residual stress in the sensitive axis direction of the tuning fork resonator caused by the mismatch in the thermal expansion coefficients of the materials during processing. Furthermore, a thermal deformation matching frame is incorporated to reduce thermal stress on the tuning fork resonator caused by inconsistent expansion or contraction deformation of different parts of the micromechanical sensing structure during operating temperature changes. This invention reduces residual stress generated during processing and thermal stress caused by changes in the sensor's operating environment, thereby reducing the impact of temperature on the resonator's output frequency and improving the stability and temperature consistency of the resonant accelerometer's output.

[0044] Please see Figure 1 This invention discloses a low-stress MEMS resonant accelerometer, comprising a lower glass substrate 1 and an upper micromechanical sensing structure 2. The glass substrate 1 supports the micromechanical sensing structure 2, which is made of single-crystal silicon and is used to sense external acceleration. Gold is deposited on the micromechanical sensing structure as electrodes 3 for signal input and output. A mass block 2-1 of the micromechanical sensing structure 2 is connected to a micro-lever amplification structure, and the output end of the micro-lever is connected to a tuning fork resonator. Supporting micro-springs are arranged at the four corners of the mass block 2-1 to suspend it. When there is an external acceleration input, the mass block 2-1 is displaced under the action of inertial force, and the inertial force is amplified by the micro-lever amplification mechanism and applied to the tuning fork resonator, causing a stiffness disturbance to the tuning fork resonator and changing its output frequency, thereby obtaining the acceleration to be measured.

[0045] The process employs SOG technology, with the upper micromechanical sensing structure 2 fabricated using standard bulk silicon technology, and the glass substrate 1 made of borosilicate glass. The glass substrate 1 and the micromechanical sensing structure 2 are bonded together via support anchor points.

[0046] With the center point of the sensitive structure of the MEMS accelerometer sensor as the origin, a coordinate system is established with the horizontal and vertical axes as the X and Y axes, respectively. The overall structure of this invention is symmetrical about the X and Y axes, and the sensitive axis is the Y axis.

[0047] The tuning fork resonators have identical structures and are symmetrical about the X-axis. When there is an external acceleration input, the natural frequency of one tuning fork resonator increases under tension, while the natural frequency of the other tuning fork resonator decreases under pressure. This causes the two resonators to form a pair of differential sensitive structures to eliminate common-mode interference.

[0048] Please see Figure 2 The micromechanical sensitive structure 2 includes a mass block 2-1, a first tuning fork resonator 2-2a, a second tuning fork resonator 2-2b, a first micro-lever amplification structure 2-3a, a second micro-lever amplification structure 2-3b, a third micro-lever amplification structure 2-3c, a fourth micro-lever amplification structure 2-3d, a first supporting micro-spring 2-4a, a second supporting micro-spring 2-4b, a third supporting micro-spring 2-4c, a fourth supporting micro-spring 2-4d, a first thermal deformation matching frame 2-5a, a second thermal deformation matching frame 2-5b, a third thermal deformation matching frame 2-5c, a first stress absorbing ring 2-6a, a second stress absorbing ring 2-6b, a third stress absorbing ring 2-6c, a fourth stress absorbing ring 2-6d, and anchor points that are symmetrical about the X-axis and Y-axis, with the sensitive axis being the Y-axis.

[0049] Please see Figure 3 It includes two sets of identical and symmetrically positioned first micro-lever amplification structures 2-3a, second micro-lever amplification structure 2-3b, third micro-lever amplification structure 2-3c, and fourth micro-lever amplification structure 2-3d. Each amplification lever structure includes a first force input end 2-3a-1, a second force input end 2-3b-1, a third force input end 2-3c-1, a fourth force input end 2-3d-1, a first fulcrum end 2-3a-2, a second fulcrum end 2-3b-2, a third fulcrum end 2-3c-2, a fourth fulcrum end 2-3d-2, a first force output end 2-3a-3, a second force output end 2-3b-3, a third force output end 2-3c-3, and a fourth force output end 2-3d-3.

[0050] Mass block 2-1 is connected to the first force input end 2-3a-1, the second force input end 2-3b-1, the third force input end 2-3c-1, and the fourth force input end 2-3d-1 of the micro lever amplification structure. The first force output end 2-3a-3 and the fourth force output end 2-3d-3 are connected to the first tuning fork resonator 2-2a, and the second force output end 2-3b-3 and the third force output end 2-3c-3 are connected to the second tuning fork resonator 2-2b.

[0051] The first supporting micro-spring 2-4a, the second supporting micro-spring 2-4b, the third supporting micro-spring 2-4c, and the fourth supporting micro-spring 2-4d are arranged at the four corners of the sensitive mass block 2-1, so that the mass block 2-1 is suspended.

[0052] When there is an acceleration input along the Y-axis, the mass block 2-1 will be displaced under the action of inertial force. The inertial force is amplified by the micro-lever amplification mechanism and acts on the first tuning fork resonator 2-2a and the second tuning fork resonator 2-2b to generate stiffness disturbance, thereby changing the output frequency and thus obtaining the acceleration to be measured.

[0053] The first tuning fork resonator 2-2a and the second tuning fork resonator 2-2b have the same structure and are symmetrical in position. When there is an external acceleration input, the natural frequency of one tuning fork resonator increases due to tension, while the natural frequency of the other decreases due to pressure, so that the two resonators form a pair of differential sensitive structures to eliminate common-mode interference.

[0054] The first tuning fork resonator 2-2a and the second tuning fork resonator 2-2b are designed at the sixth anchor point 2-7f, the thermal expansion center of the device, to reduce the residual stress caused by the mismatch in the thermal expansion coefficients of the single crystal silicon and the glass substrate after bonding.

[0055] The first thermal deformation matching frame 2-5a, the second thermal deformation matching frame 2-5b, and the third thermal deformation matching frame 2-5c are centrally fixed, and their ends expand or contract with temperature changes. The centers of the second anchor point 2-7b, the sixth anchor point 2-7f, and the fifth anchor point 2-7e are on the same horizontal line and on the X-axis of symmetry, so that the thermal deformation of the thermal deformation matching frames at the same horizontal position along the sensitive axis is consistent, thereby reducing the thermal stress transmitted to the tuning fork resonator. The first thermal deformation matching frame 2-5a and the third thermal deformation matching frame 2-5c are connected to one end of the supporting microspring to match the expansion or contraction deformation in the Y direction at the connection between the other end of the supporting microspring and the mass block 2-1.

[0056] The second thermal deformation matching frame 2-5b is connected to the first fulcrum end 2-3a-2, the second fulcrum end 2-3b-2, the third fulcrum end 2-3c-2, and the fourth fulcrum end 2-3d-2 of the amplifying lever. When the operating temperature changes, the expansion or contraction deformation at the connection points of the second thermal deformation matching frame 2-5b and the first fulcrum ends 2-3a-2, 2-3b-2, 2-3c-2, and 2-3d-2 of the amplifying lever is consistent with the expansion or contraction deformation at the first force input ends 2-3a-1, 2-3b-1, 2-3c-1, and 2-3d-1 of the mass block 2-1 and the amplifying lever, as well as at the connection points of the first force output ends 2-3a-3, 2-3b-3, 2-3c-3, and 2-3d-3 of the micro-lever and the connection points of the first tuning fork resonator 2-2a and 2-2b. This is to reduce the inconsistent expansion or contraction deformation of the accelerometer structure when the operating temperature changes, which would cause changes in the output frequency of the first tuning fork resonator 2-2a and the second tuning fork resonator 2-2b.

[0057] The first thermal deformation matching frame 2-5a, the third thermal deformation matching frame 2-5c, and the first support microspring 2-4a, the second support microspring 2-4b, the third support microspring 2-4c, and the fourth support microspring 2-4d are connected at one end to match the expansion or contraction deformation at the other end of the first support microspring 2-4a, the second support microspring 2-4b, the third support microspring 2-4c, and the fourth support microspring 2-4d. This reduces the inconsistency in expansion or contraction deformation at both ends of the first support microspring 2-4a, the second support microspring 2-4b, the third support microspring 2-4c, and the fourth support microspring 2-4d when the accelerometer's operating temperature changes. This prevents thermal stress from being generated in the first tuning fork resonator 2-2a and the second tuning fork resonator 2-2b, which in turn leads to changes in the output frequency.

[0058] The endpoints of the first force input end 2-3a-1, the second force input end 2-3b-1, the third force input end 2-3c-1, the fourth force input end 2-3d-1, the first fulcrum end 2-3a-2, the second fulcrum end 2-3b-2, the third fulcrum end 2-3c-2, the fourth fulcrum end 2-3d-2, the first force output end 2-3a-3, the second force output end 2-3b-3, the third force output end 2-3c-3, and the fourth force output end 2-3d-3 of each amplifying lever are all on the same horizontal line. This is to reduce the variation in the output frequency of the first tuning fork resonator 2-2a and the second tuning fork resonator 2-2b with temperature caused by inconsistent expansion or contraction deformation of the lever force input and force output ends when the accelerometer operates at varying temperatures.

[0059] The first stress-absorbing ring 2-6a, the second stress-absorbing ring 2-6b, the third stress-absorbing ring 2-6c, and the fourth stress-absorbing ring 2-6d are deformable flexible structures.

[0060] The first thermal deformation matching frame 2-5a and the third thermal deformation matching frame 2-5c are connected by a stress-absorbing ring 2-6a, a second stress-absorbing ring 2-6b, a third stress-absorbing ring 2-6c, a fourth stress-absorbing ring 2-6d, and first anchor points 2-7a, third anchor points 2-7c, fourth anchor points 2-7d, and sixth anchor points 2-7f. This provides sufficient support to the structure, preventing the collapse of the mass block 2-1, the first thermal deformation matching frame 2-5a, and the third thermal deformation matching frame 2-5c under impact, thus increasing the structure's impact resistance. Furthermore, it absorbs the residual stress caused by the mismatch in thermal expansion coefficients between the bonded monocrystalline silicon and the glass substrate, thereby reducing the stress on the first thermal deformation matching frame 2-5a and the third thermal deformation matching frame 2-5c.

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0062] Example 1

[0063] In existing technologies, MEMS accelerometers experience residual stress due to differences in the thermal expansion coefficients of materials during multilayer bonding processes, and temperature variations can lead to structural thermal mismatch. These issues cause decreased zero-bias stability and temperature drift, affecting measurement accuracy. For example, during the operation of aerospace equipment, internal thermal stress in the sensor can cause abnormal acceleration signal output, resulting in attitude control errors.

[0064] To address these issues, a structure capable of effectively absorbing residual stress and compensating for thermal deformation is needed. Traditional methods reduce stress by optimizing bonding processes, but cannot eliminate dynamic stress caused by temperature changes. Research has found that adding flexible elements to the supporting structure can release residual stress, while a matching frame structure can coordinate the differences in thermal expansion between different materials. Based on this, a stress-absorbing ring and a thermal deformation matching frame are integrated into the sensitive structure to form a composite stress compensation mechanism.

[0065] Therefore, this application proposes an accelerometer structure including a glass substrate, on which a micromechanical sensing structure is disposed, and electrodes are deposited on the surface of the structure. The micromechanical sensing structure includes a mass block, a symmetrical tuning fork resonator, a micro-lever amplification mechanism connecting the mass block and the resonator, supporting micro-springs arranged at the four corners, symmetrical anchor points supporting the overall structure, stress absorption rings distributed around the anchor points, and a thermal deformation matching frame connecting the supporting micro-springs and the anchor points.

[0066] The glass substrate refers to a load-bearing layer formed from high borosilicate glass, which can be bonded to the silicon structure via anodic bonding. Its coefficient of thermal expansion is close to that of silicon, thus reducing interfacial thermal stress. The micromechanically sensitive structure refers to a movable mechanical component formed by etching single-crystal silicon, containing a mass and a resonator, used to convert acceleration into changes in resonant frequency. The supporting microspring is an elastic beam structure connecting the mass and the frame, which can be designed as a folded beam or a serpentine beam, used to constrain the mass's degrees of freedom. The stress-absorbing ring is a ring-shaped flexible structure surrounding the anchor point, which can be wavy or spiral in geometry, releasing residual stress from processing through elastic deformation. The thermal deformation matching frame is a transition structure connecting the supporting spring and the anchor point, which can be U-shaped or H-shaped, used to coordinate the displacement differences between the two ends of the supporting spring during temperature changes.

[0067] Specifically, the mass block displaces along the sensitive axis under acceleration. This displacement is converted into axial stress changes in the tuning fork resonator via a micro-lever amplification mechanism, causing a shift in the resonant frequency. Four sets of supporting micro-springs restrict the mass block's movement in non-sensitive directions, and a symmetrical anchor point layout ensures balanced structural stiffness. Stress-absorbing rings compensate for the interfacial stress between the glass and silicon during bonding through flexible deformation, while also buffering external impact loads. A thermal deformation matching frame connects the fixed ends of the supporting micro-springs to the anchor points. When the temperature changes, the frame's expansion and contraction match the thermal expansion of the supporting springs, preventing spring distortion.

[0068] Compared to existing technologies, most accelerometers use rigid anchor points, leading to residual stress concentration at the root of the supporting structure. This solution disperses interfacial stress through stress-absorbing rings and actively compensates for temperature-induced deformation differences through a thermal deformation matching frame. Traditional structures do not consider the thermal stability of the resonator location; this solution places the tuning fork resonator in the thermal expansion center region, reducing the impact of the thermal gradient on its performance.

[0069] Through the above technical solutions, this application effectively reduces residual stress from processing and thermal stress caused by changes in operating temperature, thereby improving the stability of the resonant frequency. The symmetrical layout of the support structure reduces interference from insensitive axes, the stress absorption ring enhances impact resistance, and the thermal deformation matching frame maintains the linear deformation characteristics of the support spring, thus improving the temperature consistency and long-term stability of acceleration measurements.

[0070] Example 2

[0071] This application further proposes that the first tuning fork resonator and the second tuning fork resonator be arranged symmetrically about the sensitive axis to form a differential sensitive structure.

[0072] Among them, the symmetrical arrangement of the sensitive axis refers to the two tuning fork resonators being distributed mirror-symmetrically along the sensitive axis. Specifically, this can be achieved by using symmetrical geometry, size, and support point positions to ensure that the deformation directions of the two resonators are opposite when acceleration occurs. The differential sensitive structure refers to the differential processing of the output signals of the two resonators. Specifically, this can be achieved using a bridge circuit or a frequency difference detection circuit, thereby improving sensitivity by canceling common-mode interference.

[0073] Specifically, when external acceleration acts on the sensitive axis, the mass block is displaced by the micro-lever amplification mechanism, causing the first and second tuning fork resonators to experience tensile and compressive stresses respectively, resulting in opposite changes in their resonant frequencies. By detecting the frequency difference between the two resonators, common-mode errors caused by temperature changes and residual manufacturing stress can be eliminated, while the differential-mode signal caused by acceleration can be amplified. The symmetrical layout further ensures that the deformations of the two resonators under thermal expansion or mechanical impact cancel each other out, reducing the impact of asymmetric stress on measurement accuracy.

[0074] Compared to existing technologies, conventional resonant accelerometers often employ a single resonator or an asymmetrical layout, resulting in the inability to effectively eliminate temperature drift and residual stress. This solution, through differential symmetrical design, converts environmental interference into common-mode signals, significantly reducing its impact on the output.

[0075] Through the above technical solution, this application can suppress frequency drift caused by thermal stress and processing residual stress, improve the stability and sensitivity of acceleration measurement, and enhance the sensor's anti-interference ability in complex temperature environments.

[0076] Example 3

[0077] This application further proposes that the two ends of the first thermal deformation matching frame and the second thermal deformation matching frame are respectively connected to the first support microspring, the second support microspring, the third support microspring, the fourth support microspring and the first anchor point, the third anchor point, the fourth anchor point and the sixth anchor point, for matching the thermal deformation of the two ends of the support microspring in the sensitive axis direction.

[0078] The thermal deformation matching frame refers to a connection structure with specific stiffness, which can be achieved by homogenizing silicon-based materials and supporting microsprings, using the consistency of the materials' thermal expansion coefficients to achieve deformation coordination. The supporting microspring is an elastic support component connecting the mass block to the substrate, which can be implemented using folded beams or serpentine beam structures, used to transmit the inertial force caused by acceleration and allow for small displacements of the mass block. The anchor point is a rigid connection point fixed to the substrate, which can be implemented using a boss structure etched from high borosilicate glass, used to constrain the end displacement of the supporting microspring. The sensitive axis direction refers to the main measurement direction of the accelerometer, which can be defined by the coupling relationship between the mass block's motion degrees of freedom and the vibration modes of the tuning fork resonator.

[0079] Specifically, when the operating temperature changes, the fixed and free ends of the supporting microspring undergo axial deformation due to the difference in thermal expansion of the materials. The thermal deformation matching frame connects the fixed end of the supporting microspring to the anchor point, ensuring that the deformation at both ends of the supporting microspring remains consistent along the sensitive axis. For example, when the temperature rises, the fixed end of the supporting microspring undergoes thermal expansion displacement due to the constraint of the substrate, while the free end synchronously undergoes an equal displacement through the rigid connection of the thermal deformation matching frame, thereby eliminating the thermal stress gradient inside the supporting microspring.

[0080] Compared to existing technologies, traditional structures lack a thermal deformation matching frame, leading to asymmetrical deformation at both ends of the supporting microspring during temperature changes and causing axial stress accumulation in the resonator. This solution uses a rigid frame connection to forcibly constrain the synchronicity of displacement at both ends of the supporting microspring, ensuring that the deformation caused by thermal expansion is evenly distributed along the sensitive axis.

[0081] Through the above technical solution, this application effectively suppresses the asymmetric deformation of the support microspring caused by temperature changes, avoids the local concentration of thermal stress in the resonator region, and thus significantly reduces the temperature drift error of the accelerometer output frequency.

[0082] Example 4

[0083] This application further proposes that the first tuning fork resonator and the second tuning fork resonator be disposed at the thermal expansion center of the device to reduce bonding residual stress.

[0084] The thermal expansion center refers to the geometrically symmetrical center where the overall structure of the device deforms when the temperature changes. This location can be determined by calculating the thermal expansion distribution of the structure using finite element method (FEM) simulation, where the thermal expansion deformation is minimized. Bonding residual stress refers to the internal stress caused by the difference in thermal expansion coefficients between different materials during the bonding process. This stress can be mitigated by optimizing the structural layout, but it can also cause resonator frequency drift.

[0085] Specifically, when the tuning fork resonator is positioned at the center of thermal expansion, the displacement in that region is minimized during temperature changes, effectively offsetting the difference in thermal expansion between the resonator made of monocrystalline silicon and the glass substrate. During the high-temperature bonding process, the structural deformation of the thermal expansion center region is constrained, preventing localized stress concentration caused by differences in material shrinkage rates. Consequently, the thermal mismatch stress between the resonator's anchoring end and the substrate is reduced, improving the stability of the resonant frequency.

[0086] Compared to existing technologies, the tuning fork resonators in current accelerometers are typically placed at the structural edge or in asymmetrical positions, resulting in uneven distribution of residual stress along the resonator axis after bonding, which affects frequency stability. This solution places the resonator at the center of thermal expansion, enabling a symmetrical spatial distribution of thermal stress generated during bonding, and achieving stress self-compensation through the structure's own geometric symmetry.

[0087] Through the above technical solution, this application effectively reduces the impact of residual stress caused by the bonding process on the resonator, avoids the frequency drift phenomenon caused by local stress concentration in the resonator, and improves the temperature consistency and long-term stability of the accelerometer.

[0088] Example 5

[0089] This application further proposes that the first stress-absorbing ring, the second stress-absorbing ring, the third stress-absorbing ring, and the fourth stress-absorbing ring are flexible structures that connect the first thermal deformation matching frame, the third thermal deformation matching frame, and the first anchor point, the third anchor point, the fourth anchor point, and the sixth anchor point, in order to absorb residual stress and enhance impact resistance.

[0090] Among them, flexible structures refer to mechanical structures with elastic deformation capabilities, which can be implemented using folded beams or serpentine structures, releasing internal stress through localized deformation. Stress-absorbing rings are ring-shaped components surrounding sensitive structures, which can be implemented using multiple flexible beams connected in series to form a closed-loop structure, dispersing residual stress interference to the resonator through deformation. Thermal deformation matching frames are rigid frames that match the thermal expansion coefficient of the supporting microsprings, which can be formed simultaneously using single-crystal silicon material and the supporting microsprings, reducing the internal stress gradient of the structure by constraining the direction of thermal deformation. Anchor points are support connection points fixed to the substrate, which can be implemented using boss structures etched from high borosilicate glass, maintaining overall structural stability through symmetrical layout.

[0091] Specifically, when residual stress is generated in the micromechanically sensitive structure due to processing or temperature changes, the stress-absorbing ring of the flexible structure absorbs the stress energy through its own elastic deformation, preventing stress concentration from being transmitted to the tuning fork resonator. The rigid connection between the thermal deformation matching frame and the anchor point forms a stable support boundary, while the flexible connection of the stress-absorbing ring allows for slight displacement between the frame and the anchor point, further offsetting the thermal expansion difference between the monocrystalline silicon and the glass substrate. When external impact loads are applied to the structure, the folded beam structure of the stress-absorbing ring disperses the impact energy through multi-stage deformation, preventing brittle fracture of the micro-lever amplification mechanism.

[0092] Compared to existing technologies, traditional MEMS accelerometers use rigid anchors to directly support the sensitive structure, causing residual stress to be transmitted along the rigid path to the resonator, resulting in frequency drift. This solution introduces a flexible stress-absorbing ring to create a buffer interface between the anchor and the sensitive structure, transforming the linearly transmitted residual stress into local deformation of the ring structure, significantly reducing the impact of thermal mismatch stress on the resonator's operating frequency.

[0093] Through the above technical solutions, this application effectively blocks the transmission path of residual processing stress and working thermal stress, avoiding the resonant frequency shift problem caused by stress concentration. The flexible stress-absorbing ring maintains the overall structural stiffness while dissipating impact energy through controllable deformation, improving the structural reliability of the accelerometer under complex working conditions. The synergistic effect of the thermal deformation matching frame and the stress-absorbing ring ensures that the sensitive structure maintains a stable mechanical transmission path even with temperature fluctuations, improving the temperature stability of the sensor.

[0094] Example 6

[0095] This application further proposes a first stress-absorbing ring, a second stress-absorbing ring, a third stress-absorbing ring, and a fourth stress-absorbing ring to offset the difference in thermal expansion coefficients between the monocrystalline silicon and the glass substrate through deformation.

[0096] Among them, a stress-absorbing ring refers to a ring structure with elastic deformation capability, which can be implemented using folded beams or serpentine beam structures. It absorbs stress concentration at the material interface through localized flexible deformation. The difference in thermal expansion coefficient refers to the difference in linear expansion of different materials when the temperature changes. It can be achieved by matching the thermal expansion coefficients of the materials or introducing stress buffer structures, using structural deformation to compensate for the difference in thermal deformation at the interface.

[0097] Specifically, the stress-absorbing ring connects the thermal deformation matching frame and the anchor point. When the monocrystalline silicon and the glass substrate experience thermal expansion differences due to temperature changes, the stress-absorbing ring releases the interfacial shear stress through its own elastic deformation. For example, in a high-temperature environment, if the expansion of the glass substrate is greater than that of the monocrystalline silicon structure, the folded beam structure of the stress-absorbing ring undergoes bending deformation, avoiding stress accumulation caused by rigid connections. This deformation process can dynamically adapt to the material expansion behavior at different temperatures, eliminating residual stress caused by thermal mismatch.

[0098] Compared to existing technologies, traditional structures use rigid anchor points to directly fix sensitive structures, which cannot effectively mitigate the differences in thermal expansion between heterogeneous materials. This solution introduces a flexible stress-absorbing ring to transform the shear stress at the material interface into controllable deformation of the local structure, achieving active adjustment of the stress path and providing higher thermal matching tolerance compared to fixed connection methods.

[0099] Through the above technical solutions, this application effectively reduces bonding residual stress and thermal stress caused by changes in operating temperature, thus avoiding resonator frequency drift. The elastic deformation characteristics of the stress absorption ring can disperse impact load energy, improve the structural reliability of the sensor under vibration environments, and maintain the symmetry and stability of the sensitive structure.

[0100] Example 7

[0101] This application further proposes a micro-lever amplification mechanism comprising multiple sets of symmetrical first micro-lever amplification structures, second micro-lever amplification structures, third micro-lever amplification structures, and fourth micro-lever amplification structures. The endpoints of the first force input end, second force input end, third force input end, fourth force input end, first force output end, second force output end, third force output end, and fourth force output end of each micro-lever are located on the same horizontal line to eliminate frequency drift caused by inconsistent thermal deformation.

[0102] Among them, the micro-lever amplification mechanism refers to a structure that mechanically amplifies the inertial force generated by the mass block through the lever principle. Specifically, it can be realized by using silicon-based micromachining technology to form a cantilever beam structure with a fixed fulcrum, a force input end, and a force output end. Its function is to convert a small acceleration signal into a measurable change in resonant frequency.

[0103] The force input end refers to the point in the micro-lever structure that receives the inertial force transmitted by the mass block. Specifically, it can be achieved through an anchor point structure that is rigidly connected to the mass block. Its function is to transmit the displacement caused by acceleration to the lever fulcrum.

[0104] The force output end refers to the point in the micro-lever structure that transmits the amplified force to the tuning fork resonator. Specifically, it can be achieved through a flexible hinge structure connected to the root of the tuning fork resonator, which converts the amplified force into axial stress changes in the resonator.

[0105] Among them, the same horizontal line refers to the alignment of the force input end and the force output end in the direction perpendicular to the sensitive axis. Specifically, the geometric symmetry layout can be achieved through photolithography mask layout design. Its function is to ensure that the thermal expansion of each connection point remains consistent when the temperature changes.

[0106] Specifically, when an external acceleration acts on the mass block, the resulting inertial force is transmitted to the tuning fork resonator through four sets of symmetrically distributed micro-lever amplification structures. Since the input and output ends of each micro-lever are on the same horizontal line, the longitudinal displacement of each connection point remains synchronized when the structure expands due to temperature changes, avoiding misalignment of the lever arm length ratio caused by differences in thermal deformation. Therefore, the axial preload on the tuning fork resonator does not change additionally due to temperature fluctuations, thus suppressing the drift of the resonant frequency.

[0107] Compared to existing technologies, traditional micro-lever structures typically employ asymmetrical layouts or geometric alignment methods without strict constraints on the force transmission path. These can easily lead to relative displacement deviations between the input and output ends during temperature changes, resulting in amplification inaccuracies and frequency drift. In contrast, this solution achieves a self-compensation mechanism for thermal deformation by constraining the spatial positional relationship of the force transmission endpoints.

[0108] Through the above technical solution, this application effectively suppresses the fluctuation of lever amplification coefficient caused by temperature changes and eliminates the interference of thermal stress on the stability of resonant frequency, thereby improving the temperature adaptability and long-term stability of the accelerometer.

[0109] Example 8

[0110] This application further proposes bonding a glass substrate and a micromechanical sensitive structure via SOG process, wherein the glass substrate is high borosilicate glass.

[0111] SOG bonding refers to bonding the substrate and the sensitive structure by spin-coating a glass layer as an intermediate medium layer. Specifically, it can be achieved by spin-coating and depositing glass material and then heat-treating it to form a dense bonding layer. This process can reduce the stress at the bonding interface and improve the bonding strength.

[0112] High borosilicate glass refers to a type of borosilicate glass with a high boron oxide content. Specifically, it can be achieved using materials with a thermal expansion coefficient close to that of single-crystal silicon, such as Borofloat 33 or Pyrex 7740, with a thermal expansion coefficient controllable between 3.2 and 3.8 × 10⁻⁶. -6 Within a temperature range of / ℃, the difference in thermal expansion coefficient between it and monocrystalline silicon is less than 10%.

[0113] Specifically, a glass slurry is spin-coated onto the surface of a glass substrate to form an intermediate layer. This intermediate layer is then chemically bonded to a single-crystal silicon material with a micromechanically sensitive structure through heating and pressurization. The thermal expansion coefficient of the borosilicate glass substrate is close to that of single-crystal silicon, resulting in minimal difference in thermal deformation during temperature changes. This suppresses stress concentration at the bonding interface caused by thermal mismatch. The bonding layer formed by the SOG process has a uniform thickness distribution; for example, a spin-coated glass layer with a thickness of 0.5 to 2 micrometers can be used. The density of the bonding layer is controlled by adjusting the heat treatment temperature and time, preventing structural warping or cracking caused by localized stress concentration during bonding.

[0114] Compared with existing technologies, traditional methods using anodic bonding processes result in a significant difference in the coefficients of thermal expansion between the glass substrate and the silicon material. For example, the coefficient of thermal expansion of ordinary soda-lime glass is approximately 9 × 10⁻⁶. -6The temperature range of ℃ results in high residual stress at the interface after bonding. This solution, however, utilizes SOG technology combined with high borosilicate glass to improve the matching of the thermal expansion coefficients of the bonding layer material and the substrate, while simultaneously avoiding localized stress problems caused by uneven electric field distribution during anodic bonding.

[0115] Through the above technical solutions, this application effectively reduces residual stress at the bonding interface and thermal stress caused by changes in operating temperature, thereby improving the stability of the resonant frequency of the micromechanical sensitive structure. At the same time, it reduces the zero-bias drift phenomenon of the sensor caused by bonding stress, and improves the temperature consistency and long-term stability of the accelerometer.

[0116] Example 9

[0117] This application further proposes a second thermal deformation matching frame to connect the first fulcrum end, the second fulcrum end, the third fulcrum end, and the fourth fulcrum end of the micro lever, ensuring that the thermal deformation of the fulcrum end, the force input end, and the force output end is synchronized.

[0118] The second thermal deformation matching frame refers to a support frame structure made of a material with a matching coefficient of thermal expansion. Specifically, it can be made of monocrystalline silicon, the same material as the fulcrum end of the micro-lever. The consistency of the material's coefficient of thermal expansion achieves deformation coordination between the structures. The fulcrum end refers to the support node in the micro-lever mechanism that transmits forces. This can be achieved by forming a rigid connection structure using silicon-based etching processes to maintain the motion stability of the lever amplification mechanism. Synchronized thermal deformation means that the deformation generated by the structure remains consistent during temperature changes. This can be achieved through the geometrically symmetrical layout of the frame and the fulcrum end, eliminating stress concentration caused by local differences in thermal expansion.

[0119] Specifically, when the ambient temperature changes, the second thermal deformation matching frame and the micro-lever fulcrum end undergo synchronized axial expansion and contraction deformation. Since the frame and fulcrum end are made of the same material with the same coefficient of thermal expansion and are rigidly connected to form an integral structure, the longitudinal thermal expansion of the frame is uniformly transferred to the micro-lever mechanism through the fulcrum end. This synchronized deformation mechanism keeps the relative positional relationship between the lever input and output ends constant, avoiding changes in the lever ratio due to fulcrum position offset. Furthermore, the symmetrical layout of the frame balances the thermal deformation of the two fulcrums, maintaining the motion symmetry of the lever mechanism in the sensitive axis direction.

[0120] In some specific embodiments, the second thermal deformation matching frame can be designed as a rectangular ring structure with a uniform cross-sectional width, and its four connection points are rigidly fixed to the fulcrum ends of the micro-lever. The geometric center of the frame coincides with the center of symmetry of the micro-lever system, so that the thermal expansion caused by the temperature gradient is uniformly distributed along the frame axis.

[0121] Compared to existing technologies, traditional MEMS accelerometers lack a thermal deformation matching frame, with the micro-lever's fulcrum directly fixed to the substrate anchor point. When the temperature changes, the difference in thermal expansion between the substrate and lever materials causes the fulcrum position to shift, thus altering the lever amplification and causing frequency drift. This solution introduces an independent thermal deformation matching frame, transferring the fixed position of the fulcrum from the substrate to the frame structure, effectively isolating the thermal expansion difference between the substrate and lever materials. Through this technical solution, this application can eliminate the impact of temperature changes on the transmission accuracy of the micro-lever mechanism and maintain the stability of the resonant frequency. The synchronous thermal deformation mechanism between the fulcrum and the frame compensates for the difference in the thermal expansion coefficients of the materials, avoiding acceleration measurement errors caused by fulcrum position shifts and improving the sensor's operational reliability in a wide temperature range.

[0122] Example 10

[0123] This application further proposes a low-stress MEMS resonant accelerometer, whose overall structure is symmetrical about the X-axis and Y-axis, with the Y-axis being the sensing axis.

[0124] The overall structural symmetry about the X and Y axes refers to the mirror symmetry of the geometry, mass distribution, and support anchor point layout of the micromechanical sensing structure along the X and Y axes. This can be achieved by symmetrically arranged mass blocks, tuning fork resonators, micro-lever amplification mechanisms, and supporting micro-springs. The symmetrical design allows thermal deformation and residual stress to cancel each other out within the structure. The Y-axis being the sensing axis means that the acceleration detection direction coincides with the Y-axis. This can be achieved by aligning the vibration mode direction of the tuning fork resonator with the Y-axis, thereby optimizing the stress transfer efficiency along the sensing axis.

[0125] Specifically, the symmetrical structure balances the thermal expansion differences along the X and Y axes, ensuring a uniform distribution of thermal stress generated by the micromechanical sensing structure during temperature changes. For example, when temperature fluctuations cause thermal expansion differences between the glass substrate and the single-crystal silicon structure, the symmetrically arranged stress-absorbing rings and thermal deformation matching frame can simultaneously absorb the deformation, avoiding localized stress concentration. Simultaneously, the Y-axis-aligned design ensures that the force output by the micro-lever amplification mechanism is aligned with the detection direction, reducing the impact of lateral interference on the resonant frequency.

[0126] Compared to existing technologies, traditional MEMS accelerometers often employ single-axis symmetrical or asymmetrical layouts, leading to uneven thermal stress distribution and causing zero-bias drift. The symmetrical structure of this application, through a dual-axis symmetrical layout, simultaneously suppresses the effects of thermal deformation and residual stress in both the X and Y axes, significantly reducing the interference of temperature changes on the resonant frequency. Furthermore, the alignment of the sensitive axis with the Y-axis further optimizes the acceleration signal transmission path and reduces coupling errors in non-sensitive directions.

[0127] Through the above technical solution, this application effectively solves the problems of poor zero-bias stability and temperature drift caused by uneven thermal stress distribution in traditional MEMS accelerometers. The symmetrical layout allows thermal deformations inside the structure to cancel each other out, and the design along the sensitive axis improves the stress transmission efficiency in the detection direction, thereby enhancing the temperature consistency and long-term stability of the sensor.

[0128] The glass substrate is replaced with a silicon-based silicon dioxide (SiO2 / Si) composite substrate. Residual stress is further reduced, and it is compatible with CMOS processes, facilitating integration with ASICs.

[0129] The anchor points (2-7a~2-7f) adopt a radial star-shaped array (non-rectangular symmetry), with the center of the anchor point located at the thermal expansion center, which is suitable for circular chip packaging. The thermal stress distribution is isotropic, and the resistance to mechanical torsional loads is improved.

[0130] In summary, the present invention provides a low-stress MEMS resonant accelerometer with a symmetrical anchor point layout combined with a flexible stress relief ring. This significantly reduces the residual stress generated in the sensitive axis direction of the tuning fork resonator due to the mismatch of the material's thermal expansion coefficient during processing, thereby reducing the overall impact of temperature on the resonator's output frequency and improving the temperature stability of the resonant accelerometer's output.

[0131] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A low-stress MEMS resonant accelerometer, characterized in that, include: Glass substrate (1); The micromechanical sensing structure (2) is disposed on the glass substrate (1), and the surface of the micromechanical sensing structure (2) is deposited with electrodes (3). The micromechanical sensing structure (2) includes: Mass block (2-1); The first tuning fork resonator (2-2a) and the second tuning fork resonator (2-2b) are symmetrically arranged about the sensitive axis to form a differential sensitive structure. The first tuning fork resonator (2-2a) and the second tuning fork resonator (2-2b) are located at the thermal expansion center of the device to reduce bonding residual stress. The micro-lever amplification mechanism connecting the mass block (2-1) and the tuning fork resonator includes multiple sets of symmetrical first micro-lever amplification structures (2-3a), second micro-lever amplification structures (2-3b), third micro-lever amplification structures (2-3c), and fourth micro-lever amplification structures (2-3d). The endpoints of the first force input end (2-3a-1), second force input end (2-3b-1), third force input end (2-3c-1), fourth force input end (2-3d-1), first force output end (2-3a-3), second force output end (2-3b-3), third force output end (2-3c-3), and fourth force output end (2-3d-3) of each micro-lever are located on the same horizontal line to eliminate frequency drift caused by inconsistent thermal deformation. The first support micro-spring (2-4a), the second support micro-spring (2-4b), the third support micro-spring (2-4c), and the fourth support micro-spring (2-4d) are respectively set at the four corners of the mass block (2-1). The first anchor point (2-7a), the second anchor point (2-7b), the third anchor point (2-7c), the fourth anchor point (2-7d), the fifth anchor point (2-7e), and the sixth anchor point (2-7f) are symmetrically arranged to symmetrically support the micromechanical sensitive structure (2). The first stress-absorbing ring (2-6a), the second stress-absorbing ring (2-6b), the third stress-absorbing ring (2-6c), and the fourth stress-absorbing ring (2-6d) are used to reduce residual stress during processing. The first stress-absorbing ring (2-6a), the second stress-absorbing ring (2-6b), the third stress-absorbing ring (2-6c), and the fourth stress-absorbing ring (2-6d) are flexible structures that connect the first thermal deformation matching frame (2-5a), the second thermal deformation matching frame (2-5b), the third thermal deformation matching frame (2-5c) and the first anchor point (2-7a), the third anchor point (2-7c), the fourth anchor point (2-7d), and the sixth anchor point (2-7f) to absorb residual stress and enhance impact resistance. The first stress-absorbing ring (2-6a), the second stress-absorbing ring (2-6b), the third stress-absorbing ring (2-6c), and the fourth stress-absorbing ring (2-6d) offset the difference in thermal expansion coefficients between the monocrystalline silicon and the glass substrate (1) through deformation. The first thermal deformation matching frame (2-5a), the second thermal deformation matching frame (2-5b), and the third thermal deformation matching frame (2-5c) are used to reduce thermal stress caused by changes in working temperature. The two ends of the first thermal deformation matching frame (2-5a) and the second thermal deformation matching frame (2-5b) are respectively connected to the first support microspring (2-4a), the second support microspring (2-4b), the third support microspring (2-4c), and the fourth support microspring (2-4d) and the first anchor point (2-7a), the third anchor point (2-7c), the fourth anchor point (2-7d), and the sixth anchor point (2-7f) to match the thermal deformation of the two ends of the support microspring in the sensitive axis direction. The second thermal deformation matching frame (2-5b) is connected to the first fulcrum end (2-3a-2), the second fulcrum end (2-3b-2), the third fulcrum end (2-3c-2), and the fourth fulcrum end (2-3d-2) of the micro lever to ensure that the thermal deformation of the fulcrum end, the force input end, and the force output end is synchronized. Among them, the first anchor point (2-7a), the second anchor point (2-7b), the third anchor point (2-7c), the fourth anchor point (2-7d), the fifth anchor point (2-7e), the sixth anchor point (2-7f), the first stress absorbing ring (2-6a), the second stress absorbing ring (2-6b), the third stress absorbing ring (2-6c), and the fourth stress absorbing ring (2-6d).

2. The low-stress MEMS resonant accelerometer according to claim 1, characterized in that, The glass substrate (1) and the micromechanical sensitive structure (2) are bonded by SOG process. The glass substrate (1) is high borosilicate glass.

3. The low-stress MEMS resonant accelerometer according to claim 1 or 2, characterized in that, The overall structure is symmetrical about the X and Y axes, with the Y axis being the sensitive axis.

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