A full-symmetry comb-finger structure MEMS inertial device and a manufacturing method thereof

Abstract

The application provides a full-symmetry comb structure MEMS inertial device and a manufacturing method thereof, comprising a substrate, a device layer and an upper cover plate, the device layer comprising a central movable anchor point, a peripheral fixed anchor point and a plurality of sets of interlaced and nested movable combs and fixed combs, the plurality of sets of movable combs being symmetrically arranged around the movable anchor point and being elastically connected to the movable anchor point through elastic support beams, and the plurality of sets of fixed combs being fixedly connected to the fixed anchor point. The application designs the central movable anchor point as a movable structure constraint support point, the fixed anchor points are distributed on the periphery, a symmetric layout of "inner movable and outer fixed" is formed, stress is uniformly transmitted from the center to the outside, and there is no local stress concentration; meanwhile, the movable combs and the fixed combs form a ring-shaped cross structure with the movable anchor point as the center, the movable combs and the fixed combs can maximize the arrangement of the capacitor plate surface area in a limited area, and a full-symmetry differential detection mode greatly improves the signal amplitude and the anti-interference ability, which provides a possibility for realizing sub-micro-g level acceleration or high-resolution angular velocity detection.

Description

Technical Field

[0001] This invention belongs to the field of MEMS inertial sensing technology, specifically relating to a fully symmetrical comb-tooth structure MEMS inertial device and its fabrication method. Background Technology

[0002] MEMS inertial devices based on the capacitance detection principle are widely used in inertial measurement, attitude control and other fields. The existing technology mainly adopts the traditional linear comb (interdigital) structure. Although the process of this structure is relatively mature, it has inherent defects: (1) low detection accuracy, insufficient symmetry and differential detection capability, and easy to be affected by parasitic capacitance and mechanical interference, resulting in low sensitivity and signal-to-noise ratio; (2) large chip area, the linearly arranged comb unit occupies a lot of space, which is not conducive to miniaturization and integration, and the manufacturing cost is high; (3) structural stress sensitive, the traditional layout is prone to residual stress during processing or temperature change, resulting in zero drift and long-term performance instability; (4) lack of process deviation self-detection function, which requires additional test structure, increases process complexity and chip area, and makes it difficult to achieve online compensation and failure judgment, thus limiting manufacturing yield and product consistency. Summary of the Invention

[0003] The purpose of this invention is to provide a fully symmetrical comb-tooth structure MEMS inertial device, which can at least solve some of the defects in the prior art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A fully symmetrical comb-tooth structure MEMS inertial device includes a substrate, a device layer, and a top cover plate. The device layer includes a moving anchor point at the center, fixed anchor points at the periphery, and multiple sets of staggered and nested moving and fixed comb teeth. The multiple sets of moving comb teeth are symmetrically arranged around the moving anchor point and elastically connected to the moving anchor point through elastic support beams. The multiple sets of fixed comb teeth are fixedly connected to the fixed anchor point.

[0005] Furthermore, the moving anchor point is a segmented circular structure formed by splicing multiple anchor point blocks along the circumference, and each anchor point block is connected to a set of moving comb teeth.

[0006] Furthermore, the device layer also includes a detection mechanism for in-situ detection of bonding deviations in the process.

[0007] Furthermore, the detection mechanism includes a limiting detection beam, the outer end of which is rigidly connected to the fixed anchor point, and the inner end of which extends toward the moving anchor point and has an initial gap reserved between it and the elastic support beam. The size of the initial gap is smaller than the working gap between the moving comb tooth and the fixed comb tooth.

[0008] Furthermore, there are multiple limiting detection beams, which are symmetrically arranged about the moving anchor point.

[0009] Furthermore, each set of movable comb teeth includes a supporting connecting arm, a connecting main rod, and multiple movable comb tooth arms. One end of the supporting connecting arm is connected to the movable anchor point through an elastic supporting beam, and the other end extends freely along the radial direction of the device layer. The connecting main rod is vertically connected to the end of the supporting connecting arm away from the movable anchor point. The multiple movable comb tooth arms are vertically connected to the connecting main rod and are arranged at equal intervals along the extension direction of the connecting main rod.

[0010] Furthermore, the supporting connecting arm is connected to the middle of the connecting main rod, and the movable comb arms located on both sides of the supporting connecting arm are symmetrically arranged about the supporting connecting arm.

[0011] Furthermore, each set of fixed comb teeth includes a long suspension beam and multiple fixed comb tooth arms. The long suspension beam is arranged parallel to the connecting main rod of the corresponding moving comb tooth, and the multiple fixed comb tooth arms are vertically connected to the long suspension beam and are arranged in an alternating nested manner with the moving comb tooth arms on the connecting main rod.

[0012] Furthermore, a solder ring is etched on the substrate, the fixed anchor point is bonded to the solder ring, and a support anchor point is provided on the substrate at the center of the solder ring, the movable anchor point is bonded to the support anchor point.

[0013] In addition, the present invention also provides a method for fabricating the above-mentioned fully symmetrical comb-tooth structure MEMS inertial device, comprising the following steps: Etch solder rings and support anchors on the substrate, and deposit corresponding metal traces and PAD layers on the substrate; A silicon wafer is bonded to the solder ring, and the designed dynamic anchor point, dynamic comb tooth, fixed comb tooth, elastic support beam, cantilever structure, and fixed anchor point area are etched on the silicon wafer. A bonding ring is etched on the top cover plate, and the bonding ring is bonded to the surface of the silicon wafer. The wafer is then cut to form an independent MEMS inertial device.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention designs the central moving anchor point as the constraint fulcrum of the movable structure, and the fixed anchor points are distributed on the periphery, forming a symmetrical layout of "inner moving and outer fixed". The stress is uniformly transmitted from the center to the outside, without local stress concentration. At the same time, the moving and fixed comb teeth form a ring-shaped cross structure with the moving anchor point as the center, which can maximize the arrangement of the capacitor plate surface area in a limited area. Moreover, the fully symmetrical differential detection mode greatly improves the signal amplitude and anti-interference ability, making it possible to realize sub-micro-gal acceleration or high-resolution angular velocity detection.

[0015] (2) The device layer of the present invention adopts a fully symmetrical radial topology layout, which makes the stiffness characteristics and thermal expansion characteristics of the device highly consistent in all directions. It can effectively offset the asymmetric deformation caused by temperature gradient or packaging stress, significantly reduce thermomechanical cross-interference and temperature drift, and ensure performance consistency over a wide temperature range.

[0016] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the fully symmetrical comb-tooth structure MEMS inertial device of the present invention; Figure 2 This is a schematic diagram of the assembly of the substrate and device layer in the fully symmetrical comb-shaped MEMS inertial device of the present invention; Figure 3 This is a schematic diagram of the substrate structure in the fully symmetrical comb-tooth structure MEMS inertial device of this invention; Figure 4 This is a schematic diagram of the device layer in the fully symmetrical comb-tooth structure MEMS inertial device of the present invention; Figure 5 This is a schematic diagram of the interaction between a set of moving comb teeth and fixed comb teeth in the fully symmetrical comb tooth structure MEMS inertial device of the present invention; Figure 6 This is a schematic diagram of the upper cover plate in the fully symmetrical comb-tooth structure MEMS inertial device of the present invention.

[0018] Explanation of reference numerals in the attached diagram: 1. Substrate; 2. Device layer; 3. Top cover plate; 4. Solder ring; 5. Support anchor point; 6. Metal trace; 7. PAD layer; 8. Moving anchor point; 9. Elastic support beam; 10. Fixed anchor point; 11. Fixed comb tooth; 12. Moving comb tooth; 13. Limit detection beam; 14. Support connecting arm; 15. Connecting main rod; 16. Moving comb tooth arm; 17. Long cantilever beam; 18. Fixed comb tooth arm; 19. Top cover plate bonding ring; 20. Top support anchor column. Detailed Implementation

[0019] 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 embodiments of the present invention, and not all embodiments. 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.

[0020] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection", and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an abutting connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] 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 technical features indicated. Thus, a feature defined as "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.

[0023] like Figures 1 to 6As shown, this embodiment provides a fully symmetrical comb-tooth structure MEMS inertial device, including a substrate 1, a device layer 2, and a top cover plate 3. The substrate 1 provides mechanical support and electrical connection for the device layer 2. The device layer 2 includes a centrally located moving anchor point 8, peripherally located fixed anchor points 10, and multiple sets of staggered and nested moving comb teeth 12 and fixed comb teeth 11. The multiple sets of moving comb teeth 12 are arranged radially and symmetrically around the moving anchor point 8 and are elastically connected to the moving anchor point 8 via an elastic support beam 9. The multiple sets of fixed comb teeth 11 are fixedly connected to the fixed anchor point 10. The elastic support beam 9 is a flexible beam structure, which can be, but is not limited to, a spring beam, a folded beam, a U-shaped beam, or a serpentine beam, and can elastically expand, contract, and bend along the radial direction of the device layer 2. In this embodiment, during normal inertial signal detection, when the device is subjected to external acceleration or angular velocity, the moving anchor point 8 at the center of the device layer 2 remains fixed, and the elastic support beam 9 undergoes elastic bending deformation, which drives the moving comb tooth 12 to move synchronously, causing the working gap between the moving comb tooth 12 and the fixed comb tooth 11 to change periodically, thereby forming a differential capacitance signal output and realizing the inertial detection function. In this embodiment, a moving anchor point 8 located at the center of device layer 2 is designed as the constraint fulcrum of the movable structure (i.e., the moving comb teeth), and fixed anchor points 10 are distributed on the periphery, forming a symmetrical layout of "inner moving and outer fixed". The stress is uniformly transmitted from the center to the outside, without local stress concentration. At the same time, the moving and fixed comb teeth form a ring-shaped cross structure with the moving anchor point 8 as the center and are radially symmetrically distributed. Its ring-shaped radial layout has high space utilization and can maximize the arrangement of capacitor plate face area within a limited area. Moreover, the fully symmetrical differential detection mode greatly improves the signal amplitude and anti-interference capability, making it possible to realize sub-micro-gal acceleration or high-resolution angular velocity detection. It can also make the stiffness characteristics and thermal expansion characteristics of the device highly consistent in all directions, which can effectively offset the asymmetric deformation caused by temperature gradient or packaging stress, significantly reduce thermomechanical cross-interference and temperature drift, and ensure performance consistency over a wide temperature range.

[0024] Detailed, such as Figure 2 and Figure 3 As shown, the substrate 1 is made of single-crystal silicon and is a rigid support structure. A cavity for the movable structure of the device layer 2 is etched in the center. A continuous closed solder ring 4 is etched around the edge of the substrate 1 for hermetic bonding. The fixed anchor points 10 around the device layer 2 are all bonded to the solder ring 4. Metal traces 6 and PAD layers 7 are deposited on the surface of the substrate 1 to realize the electrical lead-out of the moving anchor point 8, the fixed anchor point 10 and each comb electrode, and to achieve electrical isolation through the insulating layer. A support anchor point 5 is set at the center of the solder ring 4 on the substrate 1. The moving anchor point 8 at the center of the device layer 2 is bonded and fixed to the support anchor point 5.

[0025] like Figure 6As shown, the upper cover plate 3 is made of single-crystal silicon and is a rigid protective structure. A top cavity is etched on its lower surface to provide a top movement gap for the movable structure of the device layer 2. The upper cover plate 3 has a continuously closed upper cover plate bonding ring 19 at its edge, aligned vertically with the solder ring 4 of the substrate 1. The upper cover plate bonding ring 19 is bonded to the surface of the device layer 2 away from the substrate, achieving hermetically tight vacuum bonding encapsulation of the device. The upper cover plate 3 can optionally be equipped with top support anchors 20 corresponding to the moving anchor points 8 of the device layer 2 to enhance the fixing rigidity of the moving anchor points 8. The upper cover plate 3, device layer 2, and substrate 1 are coaxially aligned and assembled to form a sealed, stable, and highly symmetrical overall structure for the MEMS inertial device.

[0026] As an optimized implementation, the moving anchor point 8 is designed as a segmented circular structure composed of multiple anchor point blocks spliced ​​along the circumference. This segmented structural design of the moving anchor point 8 provides a channel for releasing residual stress through the small gaps between each anchor point block, avoiding the annular accumulation of stress in the central region and significantly reducing the impact of bonding stress and thermal stress on the movable structure. Moreover, compared to a solid circle, the annular bonding surface formed by multiple anchor point blocks has a more uniform contact area distribution with the substrate 1, and a more stable bonding pressure distribution, reducing problems such as moving anchor point tilting and elastic support beam deformation caused by uneven bonding pressure. The number of anchor point blocks constituting the moving anchor point 8 can be consistent with the number of moving comb teeth 12 designed, and each group of moving comb teeth 12 is designed to be independently connected to one anchor point block through an elastic support beam 9; for example, in this embodiment, four groups of moving comb teeth 12 are designed (e.g., Figure 4 As shown in the figure, four quarter-circular anchor blocks are designed to be assembled into a circular moving anchor structure.

[0027] For the specific structure of the fully symmetrical annular comb sensor in device layer 2, one optional implementation is as follows: Figure 4 and Figure 5 As shown, each set of moving comb teeth 12 includes a supporting connecting arm 14, a connecting main rod 15, and multiple moving comb tooth arms 16. One end of the supporting connecting arm 14 is connected to the moving anchor point 8 through an elastic supporting beam 9, and the other end extends freely along the radial direction of the device layer 2. The connecting main rod 15 is vertically connected to the end of the supporting connecting arm 14 away from the moving anchor point 8. The multiple moving comb tooth arms 16 are vertically connected to the connecting main rod 15 and are arranged at equal intervals along the extension direction of the connecting main rod 15. The connecting main rod 15 serves as the main supporting beam for the moving comb tooth arms 16, ensuring the coaxiality and rigidity of the multiple moving comb tooth arms 16, keeping all the moving comb tooth arms 16 in the same plane, and preventing twisting or tilting during movement. Each moving comb tooth arm 16 is an independent capacitor plate, used to interlock with the fixed comb tooth arms 18 of the fixed comb tooth 11 to form a capacitance detection pair.

[0028] The optimized design connects the main rod 15 and multiple moving comb arms 16 as a single integral mold, forming an overall rigid frame. During movement, the moving comb arms 16 will not bend or twist, and will always remain parallel to the fixed comb teeth 11, avoiding capacitive parasitic effects and nonlinear errors.

[0029] Furthermore, the supporting connecting arm 14 is connected to the middle of the connecting main rod 15, and the movable comb arms 16 located on both sides of the supporting connecting arm 14 are symmetrically arranged about the supporting connecting arm 14; for example, in this embodiment, there are three movable comb arms 16, of which the middle movable comb arm 16 is on the extension line of the supporting connecting arm 14 and connected to it, and the other two movable comb arms 16 are symmetrically arranged about the supporting connecting arm 14 on both sides. This symmetrical distribution design of multiple movable comb arms 16 maximizes the number of effective capacitor plates in a limited radial space, greatly increasing the capacitance change and significantly improving the detection sensitivity of the device; on the other hand, it ensures that its motion under inertial force is pure translational motion without additional torque, and the capacitance change and displacement have a highly linear relationship, improving the stability and accuracy of the detection signal.

[0030] An optional implementation includes a fixed comb tooth structure adapted to the aforementioned moving comb tooth structure, such as... Figure 4 As shown, each set of fixed comb teeth 11 includes a long suspension beam 17 and multiple fixed comb tooth arms 18. The long suspension beam 17 is arranged parallel to the connecting main rod 15 of the corresponding moving comb tooth 12. The multiple fixed comb tooth arms 18 are vertically connected to the long suspension beam 17 and are arranged in an alternating nested manner with the moving comb tooth arms 16 on the connecting main rod 15 to form a capacitance detection pair.

[0031] Optionally, in order to improve the stability of the fixed comb teeth 11, the two ends of each set of fixed comb teeth 11 are respectively connected to two fixed anchor points 10 through beam structures.

[0032] To achieve self-detection of process deviations and further optimize the above technical solution, the device layer 2 also includes a detection mechanism for in-situ detection of bonding deviations. In some embodiments, the detection mechanism includes a limiting detection beam 13, the outer end of which is rigidly connected to the fixed anchor point 10, and the inner end of which extends toward the moving anchor point 8 and has an initial gap reserved between it and the elastic support beam 9. The size of the initial gap is smaller than the working gap between the moving comb tooth 12 and the fixed comb tooth 11, thereby achieving detection of process deviations and limiting out-of-tolerance displacements. Its working process is as follows: Normal signal detection phase: When the device is subjected to external acceleration and causes displacement, the moving anchor point 8 at the center of device layer 2 causes the elastic support beam 9 to undergo elastic deformation, and the working gap between the moving comb tooth 12 and the fixed comb tooth 11 changes, outputting a differential capacitance signal to realize the sensing of acceleration; at this time, the displacement of the elastic support beam 9 is much smaller than the initial gap, and the limit detection beam 13 and the elastic support beam 9 always remain separated and do not make contact, and the device is in normal working mode.

[0033] Process Deviation Self-Detection and Compensation Stage (Tolerable Range): When the anchor point 10 exhibits a tolerable deviation in the same direction during the bonding process (e.g., a deviation of approximately 5μm to 10μm to the right), the anchor point 10 will cause the limiting detection beam 13 and the fixed comb tooth 11 to shift as a whole. This shift will result in a change in the relative position between the fixed comb tooth 11 and the moving comb tooth 12, thereby causing a change in the capacitance value. The system can use the change in capacitance to infer and compensate for this displacement deviation. Within this deviation range, although the gap between the limiting detection beam 13 and the elastic support beam 9 will change accordingly, since there is no physical contact, the elastic support beam 9 can still freely expand and contract, the device functions normally, and the deviation is within the allowable process tolerance range.

[0034] Out-of-tolerance failure judgment stage (unacceptable range): If the bonding process deviation of anchor point 10 continues to expand beyond the predetermined threshold (e.g., deviation to the right of 10μm to 20μm), the overall offset of anchor point 10 pulling limit detection beam 13 and fixed comb tooth 11 will be too large, causing the initial gap between limit detection beam 13 and elastic support beam 9 to be completely eliminated and mechanical contact to occur. This contact will introduce additional mechanical coupling and damping, restricting the normal deflection of elastic support beam 9, making it unable to accurately respond to subsequent acceleration input, thereby triggering failure judgment, indicating that the process deviation has exceeded the allowable operating range of the device.

[0035] In this embodiment, the process monitoring function is integrated passively into the main functional structure. By using the closed / open state of the structural gap (i.e., the initial gap) between the limit detection beam 13 and the elastic support beam 9, the process deviation is converted into a measurable capacitance change and mechanical coupling effect. By monitoring the zero-point offset of the capacitance, in-situ monitoring of chip-level bonding process deviations can be achieved without external excitation or dedicated test ports, providing a direct basis for process debugging and online device calibration.

[0036] The optimized design includes multiple limiting detection beams 13, which are arranged symmetrically about the moving anchor point 8 and connected one-to-one with the fixed anchor point 10, thereby achieving symmetrical and differential detection of process deviations and improving the sensitivity and accuracy of deviation monitoring.

[0037] Optionally, the fixed comb tooth 11 can be connected to the fixed anchor point 10 through the limiting detection beam 13. On the one hand, the limiting detection beam 13 provides a stable, wobbly, and offset fixed support for the fixed comb tooth 11, ensuring that the reference electrode position of the capacitance detection is constant and guaranteeing detection accuracy and zero-point stability. On the other hand, the limiting detection beam 13 serves as a rigid transition support between the fixed comb tooth 11 and the fixed anchor point 10, which can buffer and disperse the residual stress of the fixed anchor point 10, preventing stress from being directly transmitted to the fixed comb tooth 11, thus avoiding distortion of the distance between the moving and fixed comb teeth and nonlinear capacitance.

[0038] The specific process for fabricating the aforementioned fully symmetrical comb-tooth structure MEMS inertial device is as follows: S1. Etch solder ring 4 and support anchor point 5 on substrate 1, and sputter and pattern metal on the surface of substrate 1 to form metal trace 6 and PAD layer 7.

[0039] S2. Bond a silicon wafer to the solder ring 4, and perform patterning and deep etching on the silicon wafer to form the pattern of the designed device layer 2 (including moving anchor point 8, fixed anchor point 10, moving comb tooth 12, fixed comb tooth 11, elastic support beam 9, limit detection beam 13, etc.) in one piece.

[0040] S3. Etch the upper cover bonding ring 19 on the upper cover plate 3, align the upper cover plate 3, device layer 2 and substrate 1 coaxially, and bond the upper cover bonding ring 19 to the surface of the silicon wafer (i.e. device layer 2). Complete the hermetic bonding in a vacuum environment, and form an independent MEMS inertial device after wafer testing and dicing.

[0041] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A fully symmetrical comb-tooth structure MEMS inertial device, comprising a substrate, a device layer, and a top cover plate, characterized in that: The device layer includes a central moving anchor point, peripheral fixed anchor points, and multiple sets of staggered and nested moving and fixed comb teeth. The multiple sets of moving comb teeth are symmetrically arranged around the moving anchor point and elastically connected to the moving anchor point through elastic support beams. The multiple sets of fixed comb teeth are fixedly connected to the fixed anchor point.

2. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 1, characterized in that: The moving anchor point is a segmented circular structure formed by splicing multiple anchor point blocks along the circumference, and each anchor point block is connected to a set of moving comb teeth.

3. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 1, characterized in that: The device layer also includes a detection mechanism for in-situ detection of bonding deviations in the process.

4. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 3, characterized in that: The detection mechanism includes a limiting detection beam, the outer end of which is rigidly connected to the fixed anchor point, and the inner end of which extends toward the moving anchor point and has an initial gap reserved between it and the elastic support beam. The size of the initial gap is smaller than the working gap between the moving comb tooth and the fixed comb tooth.

5. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 4, characterized in that: There are multiple limit detection beams, which are symmetrically arranged about the moving anchor point.

6. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 1, characterized in that: Each set of movable comb teeth includes a support connecting arm, a connecting main rod, and multiple movable comb teeth arms. One end of the support connecting arm is connected to the movable anchor point via an elastic support beam, and the other end extends freely along the radial direction of the device layer. The connecting main rod is vertically connected to the end of the support connecting arm away from the movable anchor point. The multiple movable comb teeth arms are vertically connected to the connecting main rod and are arranged at equal intervals along the extension direction of the connecting main rod.

7. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 6, characterized in that: The supporting connecting arm is connected to the middle of the connecting main rod, and the movable comb arms on both sides of the supporting connecting arm are symmetrically arranged about the supporting connecting arm.

8. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 6 or 7, characterized in that: Each set of fixed comb teeth includes a long suspension beam and multiple fixed comb tooth arms. The long suspension beam is arranged parallel to the connecting rod of the corresponding moving comb tooth. The multiple fixed comb tooth arms are vertically connected to the long suspension beam and are arranged in an alternating nested manner with the moving comb tooth arms on the connecting rod.

9. The fully symmetrical comb-tooth structure MEMS inertial device as described in claim 1, characterized in that: A solder ring is etched on the substrate, the fixed anchor point is bonded to the solder ring, and a support anchor point is provided on the substrate at the center of the solder ring, the movable anchor point is bonded to the support anchor point.

10. A method for fabricating a fully symmetrical comb-structure MEMS inertial device according to any one of claims 1-9, characterized in that, The process includes the following: Etch solder rings and support anchors on the substrate, and deposit corresponding metal traces and PAD layers on the substrate; A silicon wafer is bonded to the solder ring, and the designed dynamic anchor point, dynamic comb tooth, fixed comb tooth, elastic support beam, cantilever structure, and fixed anchor point area are etched on the silicon wafer. A bonding ring is etched on the top cover plate, and the bonding ring is bonded to the surface of the silicon wafer. The wafer is then cut to form an independent MEMS inertial device.

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