Self-checking resonant micro-mechanical accelerometer

Abstract

The invention provides a self-check resonant micro-mechanical accelerometer. The self-check resonant micro-mechanical accelerometer comprises a substrate; the anchoring platform is arranged above the substrate, and the anchoring platform is connected with the substrate through an anchoring part; the mass block is connected with the anchoring platform through a cantilever supporting assembly, and the cantilever supporting assembly enables the mass block to be arranged above the substrate in a suspended mode; the acceleration detection assembly comprises a resonance unit and an electrode group arranged corresponding to the resonance unit; the force transmission assembly is connected with the mass block and the resonance unit; the self-detection assembly is arranged on the outer side of the mass block and forms a variable capacitance structure with the mass block; wherein the self-detection assembly is used for providing an excitation signal with a preset size for the mass block and driving the mass block to generate an X-axis displacement response, the force transmission assembly transmits the X-axis displacement of the mass block to the resonance unit so as to change the Y-axis vibration frequency of the resonance unit, and the acceleration is determined according to the Y-axis vibration frequency of the resonance unit. And performing performance detection on the resonant micro-mechanical accelerometer based on the acceleration corresponding to the X-axis displacement response.

Description

Technical Field

[0001] The present application relates to the field of micro-electromechanical technology, and in particular to a self-testable resonant micro-mechanical accelerometer. Background Art

[0002] Vibrating beam accelerometers (VBAs) have significant application value in fields such as inertial navigation and industrial control due to their high precision, low power consumption, and excellent stability. The core operating principle of a VBA is to detect the displacement of a mass under the action of inertial force, drive the frequency shift of a resonant beam, and achieve direct conversion of acceleration to a frequency signal.

[0003] However, traditional resonant micromechanical accelerometers cannot screen out failed devices before packaging, and it is difficult to achieve online calibration of the dynamic characteristics of the mass block. How to efficiently screen out failed devices before packaging is an urgent problem to be solved in the current industry. Summary of the Invention

[0004] In order to solve the existing technical problems, the present application provides a self-testing resonant micromechanical accelerometer that can perform online calibration of the dynamic characteristics of the mass block and has in-situ self-test to screen out failed components.

[0005] The present application provides a self-testable resonant micromechanical accelerometer, comprising:

[0006] substrate;

[0007] An anchoring platform is provided above the substrate, and the anchoring platform is connected to the substrate via an anchoring portion;

[0008] a mass block connected to the anchoring platform via a cantilever support assembly, wherein the cantilever support assembly allows the mass block to be suspended above the substrate;

[0009] An acceleration detection component, comprising a resonance unit and an electrode group corresponding to the resonance unit;

[0010] A force transmission component connecting the mass block and the resonance unit;

[0011] A self-detection component is provided on the outside of the mass block and forms a variable capacitance structure with the mass block;

[0012] In which, the self-detection component is used to provide an excitation signal of a preset size to the mass block, driving the mass block to generate an X-axis displacement response. The force transmission component transmits the X-axis displacement of the mass block to the resonant unit to change the Y-axis vibration frequency of the resonant unit. The acceleration is determined according to the Y-axis vibration frequency of the resonant unit, and the performance of the resonant micromechanical accelerometer is tested based on the acceleration corresponding to the X-axis displacement response.

[0013] In the self-test resonant micromachined accelerometer provided in the above-mentioned embodiments, a self-test component is disposed outside the mass block. The self-test component and the mass block form a variable capacitor structure for providing an excitation signal of a preset magnitude to the mass block, driving the mass block to generate an X-axis displacement response. The X-axis displacement response of the mass block is converted into a resonant frequency response of the resonant unit via the force transmission component and the acceleration detection component. In this way, the self-test component can excite the mass block displacement via electrostatic force and measure the resonant frequency response, facilitating efficient screening of failed devices in the pre-packaging stage. When the self-test component is not performing its detection function, it can apply the same potential as the mass block, thereby eliminating parasitic bias electrostatic forces generated by the potential difference between the mass block and external fixed structures, such as electrodes, substrates, ground planes, or silicon structures housing the self-test resonant micromachined accelerometer, thereby physically blocking interference paths. Due to the elimination of the bias electrostatic force, the displacement of the mass block can be dominated solely by inertial force. The axial force transmitted to the resonant unit via the force transmission component can more accurately correspond to acceleration, thereby improving the linearity of the acceleration-to-frequency conversion and, in turn, enhancing detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A top view of a self-testable resonant micromachined accelerometer provided by one embodiment.

[0015] Figure 2 for Figure 1 A perspective view of a self-testable resonant micromachined accelerometer is shown.

[0016] Figure 3 for Figure 1 The three-dimensional cross-sectional view of the self-testable resonant micromachined accelerometer is shown.

[0017] Figure 4 A schematic structural diagram of a cantilever support assembly provided in one embodiment.

[0018] Figure 5 for Figure 4 Displacement distribution diagram of the cantilever support assembly shown.

[0019] Figure 6 A schematic structural diagram of a force transmission assembly provided in one embodiment.

[0020] Figure 7for Figure 6 Schematic diagram of the structure of the lever part in the force transmission assembly shown.

[0021] Figure 8 for Figure 7 The displacement distribution diagram of the lever part is shown.

[0022] Figure 9 Schematic diagram of the structure of the resonance unit in the acceleration detection component in one embodiment.

[0023] Figure 10 FIG. 4 is a structural diagram of an acceleration detection component in one embodiment.

[0024] Figure 11 for Figure 10 The displacement distribution diagram of the acceleration detection component shown.

[0025] Figure 12 1 is a diagram showing the axial sensitive modal displacement distribution of a self-testable resonant micromachined accelerometer in one embodiment.

[0026] Figure 13 FIG. 1 is a top view of a self-testable resonant micromachined accelerometer according to another embodiment.

[0027] Figure 14 for Figure 13 The displacement distribution diagram of the acceleration detection component in the self-testable resonant micromechanical accelerometer shown.

[0028] Figure 15 for Figure 13 The schematic diagram of the structure of the acceleration detection component in the self-testable resonant micromechanical accelerometer is shown.

[0029] Figure 16 Schematic diagram of a self-detection component in one embodiment.

[0030] Figure 17 FIG. 4 is a schematic diagram of a self-detection component in another embodiment.

[0031] Figure 18 FIG. 1 is a top view of a self-testable resonant micromachined accelerometer according to another embodiment.

[0032] Figure 19 FIG. 4 is a top view of a self-testable resonant micromachined accelerometer according to another embodiment.

[0033] Figure 20 FIG. 1 is a top view of a self-testable resonant micromachined accelerometer according to another embodiment. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] In order to make the purpose, technical solutions and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limiting this application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0037] In the following description, the terms "first, second, and third" are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It is understandable that "first, second, and third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0038] See also Figure 1 and Figure 2 An embodiment of the present application provides a self-testable resonant micromachined accelerometer, comprising: a substrate 10; an anchoring platform 20, disposed above the substrate 10, the anchoring platform 20 being connected to the substrate 10 via an anchoring portion 21; a mass block 50, connected to the anchoring platform 20 via a cantilever support assembly 40, the cantilever support assembly 40 allowing the mass block 50 to be suspended above the substrate 10; an acceleration detection assembly 70, comprising a resonant unit 703 and an electrode group 704 corresponding to the resonant unit 703; a force transmission assembly 60, connecting the mass block 50 and the resonant unit 703; and a self-test assembly 80, disposed outside the mass block 50, forming a variable capacitor structure with the mass block 50. Among them, the self-detection component 80 is used to provide an excitation signal of a preset size to the mass block 50, driving the mass block 50 to generate an X-axis displacement response. The force transmission component 60 transmits the X-axis displacement of the mass block 50 to the resonant unit 703 to change the Y-axis vibration frequency of the resonant unit 703. The acceleration is determined according to the Y-axis vibration frequency of the resonant unit 703, and the performance of the resonant micromechanical accelerometer is tested based on the acceleration corresponding to the X-axis displacement response.

[0039] In a resonant micromachined accelerometer, the mass block 50 generates an X-axis displacement under the action of acceleration. The force transmission assembly 60 transmits the X-axis displacement of the mass block 50 to the resonant unit 703, thereby changing the Y-axis vibration frequency of the resonant unit 703. The acceleration is determined based on the vibration frequency of the resonant unit 703. The substrate 10 is the supporting body of the self-testable resonant micromachined accelerometer. The anchoring platform 20 is located above the substrate 10. The anchoring portion 21 and the anchoring platform 20 are located in the same structural layer. The anchoring platform 20 is connected to the substrate 10 via the anchoring portion 21, forming a rigid platform structure suspended above the substrate 10. In this embodiment, the anchoring portion 21 is a single-point anchoring area, located at the geometric center of the anchoring platform 20. The planar area of ​​the anchoring platform 20 is not less than five times the planar area of ​​the anchoring portion 21. On the anchoring platform 20, the design of the single-point anchoring portion 21 at the geometric center can, on the one hand, avoid uneven distribution of mechanical stress on the anchoring platform 20. When the temperature changes, the overall structure of the self-checking resonant micromechanical accelerometer can expand almost freely in the plane, evenly release thermal stress, reduce zero bias temperature drift, and reduce zero bias error. On the other hand, it can break through the structural asymmetry introduced by the manufacturing process tolerance of the multi-anchor point architecture. The anchoring platform 20 as a whole has greater rigidity and can more effectively isolate external mechanical strain.

[0040] See also Figure 3 The substrate 10 includes a support base 11 and support columns 12 disposed on the support base 11. The support columns 12 are connected between the anchoring portion 21 and the substrate 10. Between the anchoring platform 20 and the substrate 10, only the central anchoring portion 21 is anchored and connected to the substrate 10 via the support columns 12, and the anchoring platform 20 is suspended above the substrate 10.

[0041] The self-detection assembly 80 is disposed on the outside of the mass block 50. In this embodiment, the self-detection assembly 80 is disposed at opposite ends of the mass block 50 in the sensitive axis direction and can be used to receive an excitation signal of a preset magnitude. The self-detection assembly 80 uses electrostatic force to excite the mass block 50 to generate an X-axis displacement response in the X-axis direction. The force transmission assembly 60 converts the displacement of the mass block 50 into an axial force and transmits it to the resonant unit 703, thereby changing the Y-axis vibration frequency of the resonant unit 703 and measuring the resonant frequency response of the resonant unit 703. In this way, the performance test of the resonant micromachined accelerometer can be achieved by utilizing the correspondence between the resonant frequency response of the resonant unit 703 and the excitation signal of the preset magnitude. It should be noted that the performance test of the resonant micromachined accelerometer can be used to screen for device failure before packaging the resonant micromachined accelerometer, or can be used for power-on self-testing of the resonant micromachined accelerometer before each use. The correspondence between different preset excitation signals and the resonant frequency response of the resonant unit 703 can also be used to achieve online calibration of the dynamic characteristics of the mass block 50.

[0042] When not performing detection, self-detection assembly 80 applies the same potential as mass 50 to eliminate the bias electrostatic force generated by the potential difference between mass 50 and the external fixed structure, thereby improving detection accuracy. When not performing detection, self-detection assembly 80 can be connected to the same DC bias current as mass 50, thereby maintaining the same potential as mass 50.

[0043] In the above-described embodiment, the self-testing resonant micromachined accelerometer is configured by disposing a self-testing component 80 on the outside of the mass block 50. The self-testing component 80 and the mass block 50 form a variable capacitor structure for providing an excitation signal of a preset magnitude to the mass block 50, driving the mass block 50 to generate an X-axis displacement response. The X-axis displacement response of the mass block 50 is converted by the force transmission component 60 and the acceleration detection component 70 to obtain the resonant frequency response of the resonant unit 703. In this way, the self-testing component 80 can excite the displacement of the mass block 50 through electrostatic force and measure the resonant frequency response, which is conducive to efficient screening of failed devices in the pre-packaging stage. When the self-detection component 80 does not perform the detection function, it can apply the same potential as that of the mass block 50, thereby eliminating the parasitic bias electrostatic force generated by the potential difference between the mass block 50 and the external fixed structure, such as the electrode, substrate, ground surface or the silicon structure that accommodates the self-detectable resonant micromechanical accelerometer, and physically blocking the interference path. Due to the elimination of the bias electrostatic force, the displacement of the mass block 50 can be dominated only by the inertial force, and the axial force transmitted to the resonant unit 703 through the force transmission component 60 can correspond to the acceleration more accurately, thereby improving the linearity of the acceleration-frequency conversion and further improving the detection accuracy.

[0044] In some embodiments, the mass block 50 is arranged around the periphery of the anchoring platform 20; the cantilever support assemblies 40 include a plurality of cantilever support assemblies 40, which are symmetrically arranged on opposite sides of the anchoring platform 20. The anchoring platform 20 and the mass block 50 are arranged with an inner and outer spacing, and the plurality of cantilever support assemblies 40 are arranged on the outer periphery of the anchoring platform 20 and connected between the anchoring platform 20 and the mass block 50. Each cantilever support assembly 40 can be various known beam structures, such as a straight beam, a bent beam, or a folded beam. In this embodiment, there are four cantilever support assemblies 40, which are respectively arranged at the four corners of the outer periphery of the anchoring platform 20. Notches are provided on the mass block 50 at the positions corresponding to the cantilever support assemblies 40. The cantilever support assemblies 40 are respectively located in the notches and connected between the anchoring platform 20 and the mass block 50.

[0045] Please refer to Figure 4 and Figure 5Each cantilever support assembly 40 includes an anchor beam 41 and a movable beam 42 spaced apart from each other, a node beam 43 connected to one end of the anchor beam 41 and movable beam 42, and an output beam 44 extending outward from the end of the movable beam 42 away from the node beam 43. The anchor beam 41 and movable beam 42 each extend along the Y-axis, with the end of the anchor beam 41 away from the node beam 43 connected to the anchor platform 20, and the output beam 44 connected to the mass block 50. There can be one or more anchor beams 41 and movable beam 42, each arranged parallel to and spaced apart from the other. The node beam 43 connects the same end of the anchor beam 41 and movable beam 42, forming a "X" shape. In this embodiment, there are two anchor beams 41 and two movable beams 42. The movable beams 42 are arranged outside the anchor beams 41. The output beams 44 bend outward from the end of the movable beam 42 away from the node beam 43. The two middle anchor beams 41 are connected to the anchor platform 20. The two output beams 44 on both sides extend vertically outward from the ends of the movable beams 42. The output beams 44 are parallel to the node beams 43 and are respectively connected to the mass block 50. When the axial acceleration is input, the displacement distribution of the cantilever support assembly 40 is as follows: Figure 6 As shown, the displacement response at the location of output beam 44 directly connected to mass 50 is maximum, while the displacement response at the end of anchor beam 41 connected to anchor platform 20, i.e., the displacement response transmitted to anchor platform 20 via cantilever support assembly 40, is minimum. Therefore, cantilever support assembly 40 allows mass 50 to be suspended relative to substrate 10 and controls the direction of the mass 50's sensitive axis, which is the X-axis. Under the same acceleration, the displacement response of mass 50 along the X-axis is much greater than the displacement response along the Y-axis.

[0046] Among them, the mass block 50 is connected to the anchoring platform 20 through the cantilever support assembly 40, and is configured to generate a displacement response along the X-axis under the action of acceleration in the X-axis direction. The displacement is converted into axial force through the force transmission assembly 60 and transmitted to the acceleration detection assembly 70.

[0047] In some embodiments, the acceleration detection assembly 70 includes a first acceleration detection assembly 71 and a second acceleration detection assembly 72 symmetrically disposed on either side of the anchoring portion 21. In each acceleration detection assembly 70, the resonant unit 703 includes a resonant beam extending along the X-axis. Electrode groups 704 are disposed on either side of the resonant beam and are parallel to and opposite the resonant beam. The electrode groups 704 and the resonant unit 703 form a variable capacitor structure. The resonant beam can be a single beam or a combination of multiple beams; it can be a straight beam or a curved beam; it can be any resonator structure that, under the action of the axial force transmitted by the force transmission assembly 60 based on the displacement of the mass 50 along the X-axis, deforms in the Y-axis direction, generating resonance and achieving acceleration-frequency conversion.

[0048] Please refer to Figure 6 and Figure 7 The force transmission component 60 includes a first force transmission component 61 corresponding to the first acceleration detection component 71, and a second force transmission component 62 corresponding to the second acceleration detection component 72; each force transmission component 60 includes a resonant beam support portion 601 and two lever portions 602 connected to both ends of the resonant beam support portion 601, each lever portion 602 includes a lever arm 6021, a lever input beam 6022 provided on the lever arm 6021, a lever output beam 6023 and a lever anchoring beam 6024, the lever anchoring beam 6024 connects the lever arm 6021 to the resonant beam support portion 601, the lever input beam 6022 connects the lever arm 6021 to the mass block 50, and the lever output beam 6023 connects the lever arm 6021 to the anchoring platform 20. Taking the first force transmission component 61 as an example, Figure 6 As shown, the first force transmission component 61 includes two symmetrically arranged lever parts 602 and a resonant beam support part 601. Figure 7 As shown, each lever portion 602 includes a lever arm 6021 that constitutes the main body of the lever portion 602. The lever input beam 6022, the lever output beam 6023, and the lever anchor beam 6024 are all located on the same side of the lever arm 6021 (the same side in the Y-axis direction). Specifically, the lever portion 602 and the resonant beam support portion 601 are arranged along the Y-axis direction. The lever input beam 6022 and the lever output beam 6023 are respectively located at the axial ends of the lever arm 6021. The lever input beam 6022 is connected to the mass block 50, and the lever output beam 6023 is connected to the resonant beam support platform. The resonant beam support platform serves as a transition structure between the lever portion 602 and the resonant unit 703 in the acceleration detection assembly 70. In each force transmission assembly 60, the two lever portions 602 are symmetrically arranged to offset Y-axis displacement and avoid applying additional Y-axis force to the resonant unit 703. The lever anchoring beam 6024 is arranged along the length direction of the lever arm 6021, that is, along the Y-axis direction, between the lever input beam 6022 and the lever output beam 6023, and is fixed by the anchoring platform 20, wherein the width of the lever arm 6021 is significantly larger than the width of the lever input beam 6022, the lever anchoring beam 6024 and the lever output beam 6023.

[0049] When the axial acceleration is input, the movement displacement of the lever portion 602 is as follows: Figure 8 As shown, the X-axis displacement of the mass block 50 is converted into an axial force acting on the resonant beam support platform. The calculation formula for the magnitude of the axial force transmitted from the X-axis displacement of the force transmission component 60 to the resonant unit 703 is as shown in the following formula 1:

[0050]

[0051] Among them, F out is the magnitude of the axial force, Lin is the distance between the lever anchor beam 6024 and the lever input beam 6022, L o u t The distance between the lever anchor beam 6024 and the lever output beam 6023 is adjusted by adjusting the distance Lin between the lever anchor beam 6024 and the lever input beam 6022 and the distance L between the lever anchor beam 6024 and the lever output beam 6023. o ut; the magnitude of the axial force applied to the resonance unit 703 in the acceleration detection component 70 can be changed.

[0052] The first acceleration detection component 71 and the second acceleration detection component 72 are symmetrically arranged relative to the anchoring portion 21. Figures 9 to 11 Taking the first acceleration detection component 71 as an example, the resonance unit 703 includes a resonance beam arranged along the X-axis direction, whose first end along the X-axis direction is fixed to the anchoring platform 20, and the second end is connected to the mass block 50 through the force transmission component 60. The electrode group 704 is arranged corresponding to the resonance unit 703, including a driving electrode 7041 and a detection electrode 7042. The total effective facing area of ​​the detection electrode 7042 and the resonance beam is greater than the total effective facing area of ​​the driving electrode 7041 and the resonance beam.

[0053] like Figure 9 and Figure 11As shown, the resonant beam includes a first resonant beam 7031, a second resonant beam 7032 disposed on either side of the first resonant beam 7031 and parallel to the first resonant beam 7031, and a central boss 7034 connecting the first resonant beam 7031 and the second resonant beam 7032. The opposite ends of the first resonant beam 7031 are respectively connected to the force transmission assembly 60 and the anchoring platform 20. The resonant unit 703 also includes a first comb-tooth portion 7033 disposed on the second resonant beam 7032. The first comb-tooth portion 7033 includes a plurality of first teeth 7035 extending outward from the second resonant beam 7032 along the Y-axis and spaced apart along the length of the second resonant beam 7032. The electrode group 704 includes a second comb-tooth portion 7043 corresponding to the first comb-tooth portion 7033. The second comb-tooth portion 7043 includes second teeth 7045 interlaced and spaced apart from the first teeth 7035. The second comb-tooth portions 7043 on the detection electrode correspond to the first comb-tooth portions 7033 at both ends of the second resonant beam 7032, and the second comb-tooth portion 7043 on the drive electrode 7041 corresponds to the first comb-tooth portion 7033 in the middle of the second resonant beam 7032. In this embodiment, the resonant beam is formed into a composite structure, with a comb-tooth array composed of multiple first teeth 7035 arranged in its center region. The first resonant beam 7031 has an aspect ratio of ≥80:1. The comb-tooth array is composed of at least 10 thin beams (N ≥ 10) periodically arranged along the X-axis. The length of each comb-tooth fine beam is along the Y-axis, with an aspect ratio of ≥5:1. The spacing between adjacent fine beams (i.e., adjacent first teeth 7035) is 5 to 20 μm. The comb-tooth array is fixed to the second resonant beam 7032, so that the second resonant beam 7032 can serve as the comb spine of multiple first teeth 7035, and the comb spine is connected to the central boss 7034 of the first resonant beam 7031. The sliding membrane comb-tooth array is configured on opposite sides of the resonant beam. The vibration displacement distribution of the resonant unit is shown as follows: Figure 12 shown.

[0054] The resonant frequency f0 of the resonant unit 703 can be calculated by the following formula 2:

[0055]

[0056] Wherein, keff is the effective stiffness of the resonant unit 703, which is related to the dimensional parameters of the resonant beam (thickness t, width w, length l) and is modulated by the axial external force Fx. It should be noted that the axial external force here refers to the axial force F that the force transmission component 60 transmits the X-axis displacement to the resonant unit 703. o ut. When the resonant beam is subjected to a tensile axial force, keff increases (positive sign in Formula 2); when subjected to a compressive axial force, keff decreases (negative sign in Formula 2). meff is the effective mass, which is related to the dimensional parameters of the resonant beam, the material density ρ, and the total top-view projected area Sc of the resonant beam (first resonant beam 7031, central boss 7034, comb spine, and comb tooth array).

[0057] The mass block 50 is a single integral structure, and the change of its axial displacement will generate an axial force acting synchronously on all the resonant units 703. The displacement distribution of the axial sensitive mode of the mass block 50 is as follows: Figure 12 As shown in FIG. 1 , the length change trends of the resonance unit 703 in the first acceleration detection component 71 and the resonance unit 703 in the second acceleration detection component 72 are always opposite, which causes the change directions of their resonance frequencies to be opposite. The frequencies of the resonance unit 703 in the first acceleration detection component 71 and the resonance unit 703 in the second acceleration detection component 72 are subtracted, and the resonance frequency difference is calculated based on the axial input acceleration a. in The calculation formula for determining the acceleration based on the vibration frequency of the resonant unit 703 is shown in the following formula 3:

[0058]

[0059] Wherein, λ represents the sensitivity coefficient. λ1 is the sensitivity coefficient of the resonance unit 703 in the first acceleration detection component 71, λ2 is the sensitivity coefficient of the resonance unit 703 in the second acceleration detection component 72, f01 is the resonant frequency of the resonance unit 703 in the first acceleration detection component 71, f02 is the resonant frequency of the resonant unit 703 in the second acceleration detection component 72, Δf is the resonant frequency difference, and a in is the acceleration.

[0060] By characterizing the resonant frequency difference Δf between the resonant unit 703 in the first acceleration detection component 71 and the resonant unit 703 in the second acceleration detection component 72, the sensitivity to acceleration can be improved, the secondary nonlinear coefficient can be reduced, and common mode errors such as residual stress and temperature drift can be eliminated.

[0061] When there is no acceleration input and the resonant frequencies of the two resonant units 703 in the first acceleration detection assembly 71 and the second acceleration detection assembly 72 are close, zero-position self-locking is likely to occur. That is, when the input axial acceleration is small, the differential frequency Δf barely changes with the input acceleration. In some embodiments, during the design phase, a resonant frequency difference is created between the two resonant units 703 in the first acceleration detection assembly 71 and the second acceleration detection assembly 72, shifting the self-locking region (dead zone) to a non-operating region or a low-probability region within the input acceleration range.

[0062] In each acceleration detection component 70, the electrode group 704 is arranged on both sides of the corresponding resonant beam, and forms a variable capacitance structure with the resonant beam. Figure 10In the embodiment, for a resonant unit 703 configured with a synovial comb array (first comb portion 7033), the electrode group 704 includes periodically arranged finger-shaped / comb-shaped fine beams (second comb portion 7043), which are arranged in an interlaced and parallel arrangement with the comb beams of the resonant unit 703 to achieve synovial damping drive and detection functions. For ease of description, the comb beams in the resonant unit 703 are referred to as first teeth 7035, and the comb teeth of the electrode group 704 are referred to as second teeth 7045. The electrode gap 705 between the second teeth 7045 of the electrode group 704 and the first teeth 7035 of the resonant unit 703 is formed using a deep reactive ion etching process. The width of the electrode gap 705 ranges from 2 to 4 μm, with an aspect ratio of ≥20:1, a sidewall perpendicularity deviation of ≤1°, and a dimensional standard deviation of the electrode gap 705 within a range of ±0.3 μm.

[0063] The electrode group 704 adopts differential drive and differential detection. Accordingly, the driving electrode 7041 includes a positive driving electrode and a negative driving electrode located on opposite sides of the middle of the resonant beam; the detection electrode 7042 includes two groups, which are located at both ends of the resonant beam. Each group of detection electrodes 7042 includes a positive detection electrode and a negative detection electrode located on opposite sides of the resonant beam.

[0064] by Figure 10 Taking the comb array in FIG as an example, the positive drive electrode and the negative drive electrode are the positive and negative synovial drive electrodes, respectively. The drive electrical signals applied by the positive and negative synovial drive electrodes are in opposite phases, forming a differential drive electrode pair. The differential drive electrode pairs are located on either side of the centerline of the resonant beam. The positive detection electrode and the negative detection electrode are the positive and negative synovial detection electrodes, respectively. The detection electrical signals extracted by the positive and negative synovial detection electrodes are in opposite phases, forming a differential detection electrode pair. The differential detection electrode pairs are located on either side of the resonant beam. The total number of comb teeth / electrode beams contained in the differential detection electrode pair is greater than the total number of comb teeth / electrode beams contained in the differential drive electrode pair.

[0065] Please refer to Figures 13 to 15Taking the resonant unit 703 as an example, the resonant unit 703 also includes a movable electrode disposed on a single resonant beam 7037. The electrode group 704 is configured as multiple electrode pairs parallel to and opposite the single resonant beam 7037 to achieve squeeze film damping drive and detection. A micron-scale gap 7038 between the electrode group 704 and the resonant unit 703 is formed using a deep reactive ion etching process. The width of the micron-scale gap 7038 ranges from 2 to 4 μm, with an aspect ratio ≥ 20:1, a sidewall perpendicularity deviation ≤ 1°, and a dimensional standard deviation of ≤ 0.3 μm. The electrode group 704 employs differential drive and differential detection. The drive electrodes 7041 include a positive drive electrode and a negative drive electrode disposed on opposite sides of the center of the resonant beam. The positive drive electrode and the negative drive electrode are respectively the positive and negative drive electrodes of the squeeze film drive electrode. The drive signals applied to the positive and negative drive electrodes are opposite in phase, forming a differential drive electrode pair. The detection electrodes 7042 comprise two groups, located at either end of the single resonant beam 7037. Each group of detection electrodes 7042 includes a positive detection electrode and a negative detection electrode, located on opposite sides of the single resonant beam 7037. The positive and negative detection electrodes are respectively the positive and negative electrodes of the pressed-film detection electrodes. The detection electrical signals extracted by the positive and negative electrodes are in opposite phases, forming a differential detection electrode pair. Each differential drive electrode pair is located on either side of the single resonant beam 7037. The total effective facing area of ​​the differential detection electrode pair and the single resonant beam 7037 is greater than the total effective facing area of ​​the differential drive electrode pair and the single resonant beam 7037. Compared to the sliding film drive-and-detection scheme, the pressed-film drive-and-detection scheme is more direct in controlling the resonant frequency by adjusting the voltage difference between the electrode group 704 and the single resonant beam 7037, making it easier to compensate for or balance the effects of non-ideal factors such as process errors and residual stress.

[0066] The self-detection component 80 can be a double-ended drive detection component or a differential drive detection component. The drive and detection ports of the double-ended drive detection component each contain only one phase. Figure 16 The self-detection assembly 80 includes a self-detection drive electrode 81 and a self-detection detection electrode 82, which are respectively located at opposite ends of the mass block along the sensitive axis. When performing the detection function, a DC bias is applied to the mass block, the self-detection drive electrode 81 provides an AC drive voltage, and the self-detection detection electrode 82 extracts an AC current to represent the response to the current input excitation signal of a preset magnitude.

[0067] In other embodiments, see Figure 17 and Figure 18The self-detection component 80 includes multiple groups of differential detection electrodes respectively arranged at opposite ends of the sensitive axis direction of the mass block. Each group of differential detection electrodes includes a self-detection drive electrode 81 and a self-detection detection electrode 82. The drive and detection ports of the multiple groups of differential drive detection components are each divided into two branches, and the phases of the two branches are opposite. The self-detection drive electrode 81 and the self-detection detection electrode 82 each include a pair of differential signals with opposite electrical signal phases. The capacitance change trends of the positive and negative electrodes of the self-detection drive electrode 81 and the self-detection detection electrode 82 are opposite. Specifically, the self-detection drive electrode 81 includes a self-detection drive electrode positive electrode 811 and a self-detection drive electrode negative electrode 812; the self-detection detection electrode 82 includes a self-detection detection electrode positive electrode 821 and a self-detection detection electrode negative electrode 822.

[0068] In some embodiments, the mass block 50 can be a single mass block structure or a separate dual mass block structure. Figures 18 to 20 Each mass block 50 is provided with a corresponding self-test driving electrode 81 and a self-test detection electrode 82 .

[0069] In some embodiments, as Figure 18 As shown, an isolation slot 30 is provided in the middle of the mass block 50, dividing the mass block 50 into two symmetrical parts, namely a first sub-mass block 51 and a second sub-mass block 52. The mass block 50 is physically divided into two sub-mass blocks by the isolation slot 30. At this point, the resonant frequency of the resonant unit 703 in the first acceleration detection assembly 71 is primarily affected by the axial displacement of the first sub-mass block 51 to which it is connected, while the resonant frequency of the resonant unit 703 in the second acceleration detection assembly 72 is primarily affected by the axial displacement of the second sub-mass block 52 to which it is connected. This weakens the mechanical coupling strength between the resonant units 703 in the two acceleration detection assemblies 70, helping to narrow the self-locking acceleration range.

[0070] In other embodiments, Figure 19 As shown, the anchoring platform 20, mass block 50 and anchoring portion 21 are provided with an isolation groove 30 in the middle. The anchoring platform 20, mass block 50 and anchoring portion 21 are divided into a first part and a second part symmetrically by the isolation groove 30. For example, the mass block 50 is divided into a first sub-mass block 51 and a second sub-mass block 52; the anchoring platform 20 is divided into a first anchoring sub-platform 22 and a second anchoring sub-platform 23; and the anchoring portion 21 is divided into a first sub-anchoring portion 211 and a second sub-anchoring portion 212. The mass block 50, anchoring platform 20 and anchoring portion 21 are all physically divided by the isolation groove 30. Figure 18 In the structure of the embodiment shown, the coupling strength between the first acceleration detection component 71 and the resonance unit 703 in the second acceleration detection component 72 is further weakened, and the self-locking range is further reduced.

[0071] Among them, in the self-detection component 80, the self-detection driving electrode 81 and the self-detection detection electrode 82 can adopt the sliding film transduction principle or the squeeze film transduction principle. The self-detection component 80 adopting the sliding film transduction principle can be consistent with the resonance unit 703 driven by the sliding film damping in the acceleration detection component 70, such as Figure 20 Accordingly, the self-detection component 80 using the squeeze film transducer principle can be consistent with the resonance unit 703 using the squeeze film damping drive in the acceleration detection component 70, as shown in FIG. Figure 19 Compared to the squeeze film transduction principle, the sliding film transduction principle can minimize the frequency adjustment effect on the mass block, making the frequency measurement more accurate.

[0072] It should be noted that, in an optional example, in the self-checking resonant micromechanical accelerometer, the anchoring platform 20, the cantilever support assembly 40, the mass block 50, the force transmission assembly 60, and the acceleration detection assembly 70 are all made of single-crystal silicon (Si) material. In this way, the self-checking resonant micromechanical accelerometer is designed through a geometric center-symmetrical layout and a stiffness gradient (anchoring portion 21> support column 12> resonant unit 703), combined with a single-crystal silicon one-piece molding process. In this way, the single-anchor structural design allows the entire structure to expand freely, uniformly release thermal stress, and reduce the zero-bias temperature coefficient to 0.5ppm / ℃. The anchoring platform 20 is a rigid platform that can effectively isolate 99% of external mechanical strain. This design breaks through the limitations of the multi-anchor architecture and has significant application value in high-precision fields such as aerospace.

[0073] The above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A self-testable resonant micromachined accelerometer, characterized in that: include: substrate; An anchoring platform is provided above the substrate, and the anchoring platform is connected to the substrate via an anchoring portion; a mass block connected to the anchoring platform via a cantilever support assembly, wherein the cantilever support assembly allows the mass block to be suspended above the substrate; An acceleration detection component, comprising a resonance unit and an electrode group corresponding to the resonance unit; a force transmission component, connecting the mass block and the resonance unit; A self-detection component is provided on the outside of the mass block and forms a variable capacitance structure with the mass block; In which, the self-detection component is used to provide an excitation signal of a preset size to the mass block, driving the mass block to generate an X-axis displacement response. The force transmission component transmits the X-axis displacement of the mass block to the resonant unit to change the Y-axis vibration frequency of the resonant unit. The acceleration is determined according to the Y-axis vibration frequency of the resonant unit, and the performance of the resonant micromechanical accelerometer is tested based on the acceleration corresponding to the X-axis displacement response.

2. The self-testable resonant micromachined accelerometer according to claim 1, wherein: The mass block ring is arranged on the periphery of the anchoring platform; The cantilever support assembly includes a plurality of cantilever support assemblies symmetrically arranged on opposite sides of the anchoring platform.

3. The self-testable resonant micromachined accelerometer according to claim 2, wherein: Each cantilever support assembly includes an anchor beam and a movable beam spaced apart from each other, a node beam connected to one end of the anchor beam and the movable beam, and an output beam extending outward from one end of the movable beam away from the node beam; The anchor beam and the movable beam extend along the Y axis respectively, one end of the anchor beam away from the node beam is connected to the anchor platform, and the output beam is connected to the mass block.

4. The self-testable resonant micromachined accelerometer according to claim 1, wherein: The acceleration detection component includes a first acceleration detection component and a second acceleration detection component symmetrically arranged on both sides of the anchoring portion; In each of the acceleration detection components, the resonance unit includes a resonance beam extending along the X-axis direction, the electrode group is arranged on both sides of the resonance beam and is parallel to and opposite to the resonance beam, and the electrode group includes a driving electrode and a detection electrode, which form a variable capacitance structure with the resonance unit.

5. The self-testable resonant micromachined accelerometer according to claim 4, characterized in that: The resonant beam includes a first resonant beam, a second resonant beam disposed on both sides of the first resonant beam and parallel to the first resonant beam, and a central boss connecting the first resonant beam and the second resonant beam; opposite ends of the first resonant beam are respectively connected to the force transmission assembly and the anchoring platform; The resonant unit further includes a first comb-tooth portion provided on the second resonant beam, the first comb-tooth portion including a plurality of first teeth extending outward from the second resonant beam along the Y-axis direction and arranged at intervals along the length direction of the second resonant beam; The electrode group includes a second comb-tooth portion corresponding to the first comb-tooth portion, the second comb-tooth portion includes second teeth that are staggered and spaced apart from the first teeth, the second comb-tooth portion on the detection electrode corresponds to the first comb-tooth portion at both ends of the second resonant beam, and the second comb-tooth portion on the driving electrode corresponds to the first comb-tooth portion in the middle of the second resonant beam.

6. The self-testable resonant micromachined accelerometer according to claim 4, characterized in that: The resonance unit further includes a movable electrode provided on the resonance beam; The driving electrode includes a positive driving electrode and a negative driving electrode respectively arranged on opposite sides of the middle of the resonant beam; the detection electrode includes two groups respectively arranged at both ends of the resonant beam, and each group of detection electrodes includes a positive detection electrode and a negative detection electrode respectively arranged on opposite sides of the resonant beam.

7. The self-testable resonant micromachined accelerometer according to claim 4, characterized in that: The force transmission assembly includes a first force transmission assembly corresponding to the first acceleration detection assembly, and a second force transmission assembly corresponding to the second acceleration detection assembly; Each of the force transmission components includes a resonant beam support portion and two lever portions connected to the two ends of the resonant beam support portion. Each of the lever portions includes a lever arm, a lever input beam, a lever output beam and a lever anchoring beam arranged on the lever arm. The lever anchoring beam connects the lever arm to the resonant beam support portion, the lever input beam connects the lever arm to the mass block, and the lever output beam connects the lever arm to the anchoring platform.

8. The self-testable resonant micromachined accelerometer according to any one of claims 1 to 7, characterized in that: The self-detection component includes a self-detection driving electrode and a self-detection detection electrode respectively arranged at two opposite ends of the sensitive axis direction of the mass block.

9. The self-testable resonant micromachined accelerometer according to any one of claims 1 to 7, characterized in that: The self-detection component includes a plurality of groups of differential detection electrodes respectively arranged at two opposite ends of the sensitive axis direction of the mass block, and each group of the differential detection electrodes includes a self-detection driving electrode and a self-detection detection electrode.

10. The self-testable resonant micromachined accelerometer according to any one of claims 1 to 7, characterized in that: An isolation groove is provided in the middle of the mass block, and the mass block is divided into two symmetrical parts by the isolation groove; or, An isolation groove is provided in the middle of the anchoring platform, the mass block and the anchoring portion, and the anchoring platform, the mass block and the anchoring portion are divided into a symmetrical first part and a second part by the isolation groove.

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