Amplitude-frequency composite multi-parameter resonant sensor chip based on folding isolated double island topology

Abstract

This invention belongs to the field of microelectromechanical systems (MEMS) technology and provides a multi-parameter resonant sensor chip based on a folded isolated dual-island topology. This chip addresses technical problems in existing integrated MEMS sensors, such as severe mechanical stress crosstalk, reliance on complex magnetic thin-film materials for magnetic field sensing, and difficulty in effectively decoupling a single frequency-modulated signal. The invention employs a folded beam decoupling network to construct mutually non-interfering dual-island sensing regions. In the acceleration sensing island, a five-beam tuned tuning fork structure is designed, utilizing a low-frequency modulation (FM) mechanism based on stiffness modulation to achieve high-precision measurement of in-plane X and Y axis acceleration. In the magnetic field sensing island, a centrally hollowed-out hexagonal ring resonant structure is designed, using a high-frequency amplitude modulation (AM) mechanism based on Lorentz force perturbation generated by an external magnetic field to accurately detect magnetic field strength. Based on this, the invention achieves high-precision independent measurement of acceleration and magnetic field, and has the advantages of simple fabrication process and low manufacturing cost.

Description

Technical Field

[0001] This invention belongs to the field of micro-electro-mechanical systems (MEMS) technology, and relates to multi-physical quantity composite detection technology. Specifically, it provides an amplitude-frequency composite multi-parameter resonant sensing chip based on a folded isolated dual-island topology. Background Technology

[0002] Microelectromechanical systems (MEMS) have permeated core industries such as smart terminals, automotive electronics, smart healthcare, and the ubiquitous Internet of Things. However, facing the trend of extreme modern detection environments and the urgent need for multi-source data fusion, traditional discrete detection technologies for single physical quantities are no longer sufficient to meet the system control requirements of complex systems. Therefore, composite multi-parameter sensor chips have become a cutting-edge focus of the global academic and industrial communities and are a core research direction for breaking through the barriers of system size and power consumption. In particular, the demand for composite detection of spatial acceleration and geomagnetic field is especially prominent in fields such as high-precision navigation, industrial robot motion control, and autonomous driving.

[0003] Resonant MEMS sensors use micro-mechanical oscillators as the core sensing unit. They accurately characterize target parameters by capturing the drift of the structure's natural frequency or dynamic amplitude caused by external physical field disturbances. Compared with traditional piezoresistive or electrostatic capacitive detection methods, which are easily affected by thermal noise and parasitic parameters, resonant structures can directly output quasi-digital frequency domain signals with strong anti-interference capabilities. At the same time, relying on mature bulk silicon deep trench etching or surface micromachining technology, the micro-resonant structure can be integrated in situ with the subsequent CMOS signal conditioning circuit on the same wafer, resulting in high system integration and device consistency.

[0004] Due to significant differences in the physical characteristics and sensing mechanisms of various environmental parameters, the traditional solution is to physically splice multiple structurally independent, single-function resonant MEMS sensor chips in a composite sensing system. This discrete, package-level splicing leads to a dramatic increase in system size and packaging cost. Therefore, how to achieve monolithic wafer-level integration on the same substrate has become a hot topic for researchers. However, this integration method faces many insurmountable technical bottlenecks. First, severe mechanical stress crosstalk; in monolithic integrated systems, inertial measurements such as acceleration usually rely on the displacement of suspended microstructures such as large masses under low-frequency acceleration, while magnetic field measurements usually rely on the high-frequency small deformation of rigid structures. When these two types of sensing units are located on the same substrate, the large mass will generate strong inertial stress under acceleration, which will be directly transmitted to the magnetic field sensing unit through the shared substrate, thus causing severe parasitic mode interference and crosstalk errors. Second, poor compatibility in manufacturing processes; existing integrated magnetic field sensors mostly rely on the magnetostrictive effect, usually requiring the introduction of sputtering or electroplating processes for special magnetic material thin films outside of standard MEMS manufacturing processes, greatly increasing the complexity and manufacturing cost of standard processes. In addition, the inherent hysteresis and nonlinear effects of magnetic materials will seriously degrade the quality factor and long-term stability of resonators. Third, difficulty in signal readout and decoupling; existing multi-parameter resonant sensors mostly use a single frequency modulation (FM) mechanism to output signals. When the environmental acceleration and magnetic field change simultaneously, the frequencies of each resonant structure will drift unpredictably.

[0005] Therefore, how to achieve monolithic integration of magnetic field and acceleration physical quantities on the same substrate without introducing complex magnetic materials, and how to achieve parametric decoupling in three-dimensional topology and signal extraction mechanism, has become a key technical problem that has been continuously concerned by those skilled in the art and urgently needs to be solved. Summary of the Invention

[0006] The object of the present invention is to provide a frequency-amplitude composite multi-parametric resonant sensing chip based on a folded isolation double-island topology, aiming to solve the technical problems existing in existing integrated MEMS sensors, such as serious mechanical stress crosstalk, magnetic field sensing relying on complex magnetic thin film materials, and difficulty in effectively decoupling a single frequency modulation signal. The present invention adopts a folded beam decoupling network structure with spatial stress blocking characteristics to construct non-interfering "double-island" sensing regions. On the acceleration sensing island, a five-beam tuned tuning fork (five tuning forks) structure is designed. By using the frequency modulation (FM) mechanism in which the low-frequency out-of-plane anti-phase vibration mode is subjected to stiffness modulation by the inertial mass block, high-precision measurement of the in-plane X-axis and in-plane Y-axis accelerations is achieved. At the same time, on the magnetic field sensing island, a hexagonal ring resonant structure with a hollow center is designed. By using its high-frequency out-of-plane warping vibration mode and the Lorentz force generated by the alternating current under an external magnetic field to perturb the vibration state of the resonant structure, accurate detection of the magnetic field strength is achieved by means of a high-frequency amplitude modulation (AM) mechanism. Through the dual decoupling design of spatial double-island folding isolation and frequency-amplitude orthogonal reading (FM-AM), independent and accurate measurement of the two physical quantities of acceleration and magnetic field is achieved. Moreover, the entire folded double-island structure and metal interconnection traces can rely on the standard bulk silicon micromachining process and be simultaneously released in the same etching process flow, without introducing an additional magnetic sensitive material deposition process, significantly reducing the manufacturing cost of the multi-parametric sensing chip.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The frequency-amplitude composite multi-parametric resonant sensing chip based on a folded isolation double-island topology adopts a double-island topology and includes: a silicon substrate 1 and an acceleration sensing island 2 and a magnetic field sensing island 3 arranged therein;

[0009] The silicon substrate 1 is distributed in a "day" - shaped topology along the XOY plane (horizontal plane), and the acceleration sensing island 2 and the magnetic field sensing island 3 are respectively suspended in two hollow regions of the silicon substrate 1;

[0010] The acceleration sensing island 2 has a 90° rotationally symmetric structure along the XOY plane (horizontal plane) and includes: a central inertial mass block 21 and a five-tuning-fork resonant unit group 22; the central inertial mass block 21 is located at the center of the acceleration sensing island, and the five-tuning-fork resonant unit group 22 is composed of four five-tuning-fork resonant units. The central inertial mass block 21 is suspended and connected to the silicon substrate through the four five-tuning-fork resonant units;

[0011] The five-tuning-fork resonant unit includes: a first resonant silicon substrate layer 221, a first piezoelectric thin film 222, a first input electrode 223, and a first output electrode 224; the first resonant silicon substrate layer 221 adopts a parallel five-beam tuning fork structure with the roots of both sides converging, and one root is connected to the central inertial mass block 21, and the other root is connected to the silicon substrate 1; the first piezoelectric thin film 222 is finger-shaped and is correspondingly disposed on each beam of the first resonant silicon substrate layer 221; the first input electrode 223 and the first output electrode 224 are arranged in an interdigitated manner and are correspondingly disposed on the first piezoelectric thin film 222;

[0012] The magnetic field sensing island 3 has a 180° rotationally symmetric structure along the XOY plane (horizontal plane), including: a folded beam decoupling network 31 and a hexagonal resonant unit 32;

[0013] The folded beam decoupling network 31 consists of a suspended frame 311 and a multi-segment double-ended folded beam group 312. The suspended frame 311 has a square closed loop frame structure along the XOY plane. The multi-segment double-ended folded beam group 312 consists of four multi-segment double-ended folded beams. The suspended frame 311 is connected to the silicon substrate through the four multi-segment double-ended folded beams.

[0014] The hexagonal resonant unit 32 is located at the center of the magnetic field sensing island 3 and includes: a second resonant silicon substrate layer 320, a second piezoelectric thin film 321, a first Lorentz force wire circuit 322, a second output electrode 323, and a second Lorentz force wire circuit 324. The second resonant silicon substrate layer 320 has a regular hexagonal closed ring frame structure along the XOY plane. The second resonant silicon substrate layer 320 has six anchor beams extending radially outward along three diagonal directions, which are connected to the suspension frame 311. The second piezoelectric thin film 321 is disposed on the second resonant silicon substrate layer 320, the second output electrode 323 is disposed on the second piezoelectric thin film, and the first Lorentz force wire circuit 322 and the second Lorentz force wire circuit 324 are disposed together around the second piezoelectric thin film 321.

[0015] Furthermore, the silicon substrate 1 has a sandwich-type composite stacked structure along the Z-axis direction, which includes, from bottom to top, a bottom supporting silicon layer 13, an intermediate buried oxide layer 12, and a highly doped conductive silicon layer 11.

[0016] Furthermore, in the five-tone fork resonant unit, the three input fingers of the first input electrode 223 correspond to the first, third, and fifth beams of the first resonant silicon substrate 221, and the three input fingers are connected by interconnects; the two output fingers of the first output electrode 224 correspond to the second and fourth beams of the first resonant silicon substrate 221, and the two output fingers are connected by interconnects; the first input electrode 223 is connected to the input electrode disk 225 by interconnects, and the first output electrode 224 is connected to the first output electrode disk 226 by interconnects; grounding electrode disks are correspondingly provided on both sides of the input electrode disk 225 and the first output electrode disk 226; and a first isolation oxide layer 4 is provided between the input electrode disk 225, the first output electrode disk 226 and the silicon substrate, and a first isolation oxide layer is provided between all interconnects and the first resonant silicon substrate 221.

[0017] Furthermore, the multi-segment double-ended folding beam has an H-shaped topology, with one end connected to the middle suspended frame and the other end connected to the silicon substrate through an anchor point.

[0018] Furthermore, the first Lorentz force wire circuit 322 is connected to the first wire circuit electrode disk 325 via interconnects, the second output electrode 323 is connected to the second output electrode disk 326 via interconnects, and the second Lorentz force wire circuit 324 is connected to the second wire circuit electrode disk 327 via interconnects. The first wire circuit electrode disk 325, the second output electrode disk 326, and the second wire circuit electrode disk 327 are sequentially disposed on the suspension frame 311, and grounding electrode disks are respectively disposed on the outer sides of the first wire circuit electrode disk 325 and the second wire circuit electrode disk 327. In addition, a second isolation oxide layer 5 is disposed between the first Lorentz force wire circuit 322, the second Lorentz force wire circuit 324 and the second resonant silicon substrate layer 320, a second isolation oxide layer is disposed between the first wire circuit electrode disk 325, the second output electrode disk 326, the second wire circuit electrode disk 327 and the suspension frame 311, and a second isolation oxide layer is disposed between all interconnects and the second resonant silicon substrate layer 320.

[0019] Furthermore, in the five-tuning-fork resonator unit group 22, a pair of five-tuning-fork resonator units along the Y-axis direction are used to detect in-plane Y-axis acceleration, and a pair of five-tuning-fork resonator units along the X-axis direction are used to detect in-plane X-axis acceleration.

[0020] Furthermore, the working process of the acceleration sensing island 2 is as follows: for any five-tone fork resonator, an excitation signal is applied to the first input electrode to excite the five-tone fork resonator to work in the out-of-plane reverse vibration mode, and an acceleration sensing signal is output by the first output electrode. The acceleration is characterized by the frequency offset of the acceleration sensing signal. In addition, for a pair of five-tone fork resonators in the X-axis or Y-axis direction, the acceleration measurement result is obtained by signal differential processing.

[0021] Furthermore, the working process of the magnetic field sensing island 3 is as follows: a pair of differential alternating voltage signals of the same magnitude but opposite polarity are applied to the first Lorentz force conductor loop and the second Lorentz force conductor loop to excite the hexagonal resonant unit to vibrate in the out-of-plane warping vibration mode, and the magnetic field sensing signal is output through the second output electrode. The magnetic field is characterized by the amplitude of the magnetic field sensing signal.

[0022] Based on the above technical solution, the present invention has the following beneficial effects:

[0023] 1. This invention proposes an amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology. By adding a folded beam decoupling network around the hexagonal resonant unit used for magnetic field sensing, and utilizing the coupling constraint effect of the multi-ended double-ended folded beam group, the propagation of the large-amplitude in-plane stress generated by the left mass block under acceleration to the right magnetic field sensing island is effectively suppressed. This prevents the hexagonal resonant unit from experiencing resonant frequency shift and parasitic mode interference due to in-plane stress caused by acceleration, thus preventing crosstalk errors caused by mechanical stress. Furthermore, the equivalent mass of the five-tone fork resonant unit proposed in this invention is much larger than that of the hexagonal resonant unit. Therefore, the Lorentz force it experiences in the magnetic field is small, making it difficult to effectively disturb the five-tone fork resonant unit and preventing the magnetic field signal from interfering with acceleration measurement.

[0024] 2. In the multi-parameter resonant sensor chip proposed in this invention, the shared silicon substrate framework relies on the buried oxide layer to construct a natural acoustic impedance mismatch barrier, which effectively constrains acoustic energy; in the surface metal structure of the two sensing islands, all electrodes, electrode disks, interconnects, and wire loops are formed in one step using the same metal, which greatly reduces the number of photolithography and etching masks and lowers manufacturing costs.

[0025] 3. In the multi-parameter resonant sensing chip proposed in this invention, acceleration measurement is based on the low-frequency (KHz) out-of-plane antiphase vibration mode of the five-tuning-fork resonant unit, while magnetic field measurement is based on the high-frequency out-of-plane warping vibration mode of the hexagonal resonant unit. Furthermore, the acceleration measurement adopts a frequency modulation (FM) mechanism for output, and the magnetic field measurement adopts an amplitude modulation (AM) mechanism for output. The combination of two completely different physical sensing mechanisms and frequency bands completely eliminates electrical parasitic feedthrough and signal aliasing between the two resonant units, ensuring the accuracy and reliability of the output of each signal.

[0026] 4. In the multi-parameter resonant sensor chip proposed in this invention, for magnetic field sensing, a hexagonal resonant unit with a central hollowed-out design is paired with radial diagonal support anchor points. The hollowed-out design significantly reduces the equivalent mass of the resonant unit and significantly improves the mechanical response sensitivity of the resonant unit to weak Lorentz forces. In addition, the radial diagonal anchor points perfectly match the high-frequency out-of-plane warping vibration mode (the vibration displacement at the six vertices is 0), achieving low anchor point loss. At the same time, by using pure metal wiring and driving through the Lorentz force mechanism, the hysteresis error and other problems existing in traditional magnetostrictive materials are avoided.

[0027] 5. In the multi-parameter resonant sensor chip proposed in this invention, for acceleration sensing, the five-tone fork resonant unit has higher axial force sensitivity than the double-ended fixed beam resonant unit. Therefore, it has a larger resonant frequency offset for the same magnitude of acceleration. In addition, a pair of five-tone fork resonant units are used for a single axis (X-axis or Y-axis). Taking the upper and lower resonant units as an example, when the mass block is subjected to positive Y-axis acceleration, the upper resonant unit is subjected to axial pressure from the mass block, while the lower resonant unit is subjected to axial tension from the mass block. The resonant frequency offset directions of the two resonant units are opposite. Subsequently, the signal processing circuit can perform differential operation on the signals of the two resonant units to improve the sensitivity by two times, while also suppressing common-mode interference such as temperature. Attached Figure Description

[0028] Figure 1 A three-dimensional structural schematic diagram of the amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated double-island topology provided by the present invention.

[0029] Figure 2 This is a top view of the amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology provided by the present invention.

[0030] Figure 3 The diagram below shows the top-view structure of the amplitude-frequency composite multi-parameter resonant sensor chip based on the folded isolated double-island topology provided by the present invention.

[0031] Figure 4 This is a three-dimensional structural diagram of the acceleration sensing island provided by the present invention.

[0032] Figure 5 This is a partially enlarged structural diagram of the acceleration sensing island provided by the present invention.

[0033] Figure 6 This is a three-dimensional structural diagram of the magnetic field sensing island provided by the present invention.

[0034] Figure 7 This is a partially enlarged structural diagram of the magnetic field sensing island provided by the present invention.

[0035] Figure 8 The graph shows the variation of the resonant frequency of the five-tone fork resonant unit of the acceleration sensing island provided by the present invention with the Y-axis acceleration.

[0036] Figure 9 The curve showing the change of output current of the hexagonal resonant unit of the magnetic field sensing island provided by the present invention with the X-axis magnetic field strength.

[0037] Figure 10 The curve showing the change of output current of the hexagonal resonant unit of the magnetic field sensing island provided by the present invention with the Z-axis magnetic field strength.

[0038] In the above figures: 1. Silicon substrate; 11. Highly doped conductive silicon layer; 12. Intermediate buried oxide layer; 13. Bottom supporting silicon layer; 2. Acceleration sensing island; 21. Central inertial mass block; 22. Five-tone fork resonator unit group; 221. First resonant silicon substrate layer; 222. First piezoelectric thin film; 223. First input electrode; 224. First output electrode; 225. Input electrode disk; 226. First output electrode disk; 3. Magnetic field sensing island; 31. Folded beam decoupling network 311. Suspended frame; 312. Multi-segment double-ended folding beam assembly; 32. Hexagonal resonant unit; 320. Second resonant silicon substrate layer; 321. Second piezoelectric thin film; 322. First Lorentz force wire circuit; 323. Second output electrode; 324. Second Lorentz force wire circuit; 325. First wire circuit electrode disk; 326. Second output electrode disk; 327. Second wire circuit electrode disk; 4. First isolation oxide layer; 5. Second isolation oxide layer. Detailed Implementation

[0039] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0040] To facilitate understanding, the technical terms used in this invention are explained as follows: 1) Dual-island topology: refers to two sensing regions on the same semiconductor substrate that are mechanically independent and used to sense different physical quantities, constructed through physical spatial division and micromechanical structure suspension; 2) Highly doped conductive silicon layer: refers to a single-crystal silicon layer that has undergone heavy ion implantation or diffusion processes (such as P-type or N-type heavy doping) to achieve extremely low resistivity (typically below 0.01 Ω·cm), making it electrically equivalent to a metal thin film. In this invention, the highly doped conductive silicon layer provides both high Q-value mechanical support and a unified ground for the entire chip; 3) Resonant frequency: refers to the natural frequency of the micromechanical structure in a specific vibration mode. This frequency is determined by the ratio of the structure's equivalent stiffness to its equivalent mass. In this invention, the resonant frequency is not only the fundamental frequency of the device but also the carrier of the sensed physical quantity. In the acceleration sensing island, the acceleration value is extracted by detecting the shift in the resonant frequency; 4) Positive / inverse piezoelectric effect: The inverse piezoelectric effect specifically refers to the physical process that causes periodic mechanical deformation of a piezoelectric film when an alternating electric field is applied in the thickness direction of the film, which is used to excite the resonance of the structure; the direct piezoelectric effect specifically refers to the physical process that induces charge accumulation on the surface of a piezoelectric film when it deforms with the mechanical structure, which is used to extract the resonance signal or stress state electrically; 5) Lorentz force: refers to the force exerted on a moving charge in a magnetic field. In this invention, it specifically refers to the alternating mechanical force generated by the interaction between the Lorentz force conductor loop on the right magnetic field sensing island and the DC magnetic field to be measured after a high-frequency AC reference current is passed through it. This force serves as a driving source and directly excites the hexagonal resonator to generate a resonant response proportional to its magnitude, thereby realizing amplitude modulation (AM) sensing of the magnetic field strength; 6) Fixed anchor point: refers to the physical connection point between the suspended micromechanical structure inside the chip in the microelectromechanical system and the external rigid substrate.

[0041] Based on this, this embodiment provides an amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology. The dual-island topology specifically includes: a silicon substrate 1 and an acceleration sensing island 2 and a magnetic field sensing island 3 disposed in the silicon substrate.

[0042] like Figure 1 As shown, the silicon substrate 1 has a sandwich-like composite stacked structure along the Z-axis (vertical direction), which includes, from bottom to top, a bottom supporting silicon layer 13, an intermediate buried oxide layer 12, and a highly doped conductive silicon layer 11. The highly doped conductive silicon layer 11 is made of heavily doped P-type single crystal silicon with low resistivity and serves as the chip's common ground reference. The intermediate buried oxide layer 12 forms an acoustic impedance mismatch interface in the physical domain, which effectively cuts off the leakage path of the acoustic wave energy of the resonant unit to the bottom supporting silicon layer 13, thereby improving the energy confinement efficiency of the structure and the overall quality factor (Q value) of the system.

[0043] The silicon substrate 1 has a figure-eight topological distribution along the XOY plane (horizontal plane), and the acceleration sensing island 2 and the magnetic field sensing island 3 are respectively suspended in two hollow areas of the silicon substrate 1;

[0044] As Figure 2 With Figure 3 shown, the acceleration sensing island 2 has a 90° rotational symmetry structure along the XOY plane (horizontal plane), and includes: a central inertial mass block 21 and a five-fork resonator unit group 22;

[0045] The central inertial mass block 21 is located at the center of the acceleration sensing island, and adopts a rectangular silicon block structure with a relatively large mass. The role of this rectangular silicon block is to generate inertial forces in the X-axis and Y-axis in the plane under the action of accelerations in the in-plane X-axis and Y-axis and act on the five-fork resonator unit group 22; this rectangular silicon block structure has the same thickness as the silicon substrate 1 in the Z-axis direction, so the mass of the central inertial mass block can be greatly increased, thereby improving the acceleration sensing sensitivity;

[0046] The five-fork resonator unit group 22 is composed of four five-fork resonator units. The central inertial mass block 21 is suspended on the silicon substrate 1 through four five-fork resonator units; one end of the five-fork resonator unit is connected to the central inertial mass block 21, and the other end is connected to the silicon substrate 凭着1 through an anchor point, so as to convert the inertial force of the central inertial mass block 21 into a stress change inside the silicon beam, thereby causing the resonance frequency of the resonator unit to shift; in the five-fork resonator unit group 22, a pair of five-fork resonator units arranged along the Y-axis are used to detect the in-plane Y-axis acceleration, and a pair of five-fork resonator units arranged along the X-axis are used to detect the in-plane X-axis acceleration;

[0047] As Figure 4 With Figure 5As shown, the five-tuning-fork resonant unit includes: a first resonant silicon substrate layer 221, a first piezoelectric thin film 222, a first input electrode 223, and a first output electrode 224; wherein, the first resonant silicon substrate layer 221 adopts a parallel five-beam tuning fork structure with the roots of both sides converging, and one root is connected to the central inertial mass block 21, and the other root is connected to the silicon substrate 1; the first piezoelectric thin film 222 is finger-shaped and is correspondingly disposed on each silicon beam of the first resonant silicon substrate layer 221; the first input electrode 223 and the first output electrode 224 are arranged in an interdigitated manner and are correspondingly disposed on the first piezoelectric thin film 222; specifically, along the X-axis direction, the three fingers of the first input electrode 223 are correspondingly disposed on the first, third, and fifth silicon beams of the first resonant silicon substrate layer 221. The first output electrode 224 has two fingers on the piezoelectric film on the second and fourth silicon beams of the first resonant silicon substrate 221, respectively, and the two fingers are connected by interconnects. The first input electrode 223 is connected to the input electrode disk 225 by interconnects, and the first output electrode 224 is connected to the first output electrode disk 226 by interconnects. Grounding electrode disks are respectively provided on both sides of the input electrode disk 225 and the first output electrode disk 226. All electrode disks are disposed on the silicon substrate. Furthermore, a first isolation oxide layer 4 is provided between the input electrode disk 225 and the silicon substrate, between the first output electrode disk 226 and the silicon substrate, and between all interconnects and the first resonant silicon substrate 221.

[0048] like Figure 2 and Figure 3 As shown, the magnetic field sensing island 3 has a 180° rotationally symmetric structure along the XOY plane (horizontal plane), including: a folded beam decoupling network 31 and a hexagonal resonant unit 32;

[0049] like Figure 6 and Figure 7 As shown, the folded beam decoupling network 31 consists of a suspended frame 311 and a multi-segment double-ended folded beam group 312. The suspended frame 311 has a square closed-loop silicon frame structure along the XOY plane. The multi-segment double-ended folded beam group 312 consists of four identical multi-segment double-ended folded beams. Each multi-segment double-ended folded beam has an H-shaped topology, with one end connected to the middle suspended frame and the other end connected to the silicon substrate through an anchor point.

[0050] The hexagonal resonant unit 32 is located at the center of the magnetic field sensing island 3 and includes: a second resonant silicon substrate 320, a second piezoelectric thin film 321, a first Lorentz force wire circuit 322, a second output electrode 323, and a second Lorentz force wire circuit 324. The second resonant silicon substrate 320 has a regular hexagonal closed ring silicon frame structure along the XOY plane (the central area has a hollow release area that runs through the upper and lower surfaces). The second resonant silicon substrate 320 has six anchor beams extending radially outward along three diagonal directions, which are connected to the suspension frame 311. The second piezoelectric thin film 321 is disposed on the second resonant silicon substrate 320, the second output electrode 323 is disposed on the second piezoelectric thin film, and the first Lorentz force wire circuit 322 and the second Lorentz force wire circuit 324 are disposed together around the second piezoelectric thin film 321.

[0051] The first Lorentz force wire circuit 322 is connected to the first wire circuit electrode disk 325 via an interconnect line. The second output electrode 323 is connected to the second output electrode disk 326 via an interconnect line. The second Lorentz force wire circuit 324 is connected to the second wire circuit electrode disk 327 via an interconnect line. The first wire circuit electrode disk 325, the second output electrode disk 326, and the second wire circuit electrode disk 327 are sequentially disposed on the suspension frame 311. Grounding electrode disks are respectively disposed on the outer sides of the first wire circuit electrode disk 325 and the second wire circuit electrode disk 327. Furthermore, a second isolation oxide layer 5 is disposed between the first Lorentz force wire circuit 322, the second Lorentz force wire circuit 324 and the second resonant silicon substrate 320, between the first wire circuit electrode disk 325, the second output electrode disk 326, the second wire circuit electrode disk 327 and the suspension frame 311, and between all interconnect lines and the second resonant silicon substrate 320.

[0052] Furthermore, the first isolation oxide layer, the second isolation oxide layer, and the intermediate buried oxide layer are all made of silicon dioxide, the thickness of the isolation oxide layer is 0.2μm~1μm, and the thickness of the intermediate buried oxide layer is 80μm~100μm.

[0053] Furthermore, both the first and second piezoelectric films are piezoelectric material films prepared by physical vapor deposition (PVD), magnetron sputtering, or spin coating processes. The piezoelectric materials include, but are not limited to, aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), or polyvinylidene fluoride (PVDF), and the thickness of each piezoelectric film is 0.1 μm to 1 μm.

[0054] Furthermore, all electrode pads, electrodes, interconnects, and wire loops are made of the same metal material and are deposited and patterned in the same microfabrication process step; the metal material includes, but is not limited to, gold (Au), aluminum (Al), molybdenum (Mo), platinum (Pt), copper (Cu), silver (Ag), or nickel (Ni), and its thickness is between 0.5 μm and 1 μm.

[0055] Furthermore, the silicon substrate, the first resonant silicon substrate layer, the second resonant silicon substrate layer, and the folded beam decoupling network are all integrally formed by the same microfabrication process, and the thickness is 50μm~400μm.

[0056] In terms of working principle, any resonant structure possesses numerous inherent resonant frequencies, which are related to the material properties, geometry, and mechanical boundary conditions of the structure itself. For the out-of-plane reverse vibration mode of the five-tone fork resonator unit, the formula for its resonant frequency when not subjected to axial stress is:

[0057] ,

[0058] in, The resonant frequency when not subjected to axial stress. The thickness of the five-tone fork beam in the bending direction is [thickness value]. This is the equivalent Young's modulus of the resonant unit. This represents the equivalent density of the resonant unit.

[0059] When an external acceleration occurs, the inertial force of the mass block causes axial stress on the tuning fork beam, at which point the resonant frequency of the resonant unit changes. for:

[0060] ,

[0061] in, The magnitude of the axial stress is given. The length of the tuning fork beam. Let be the moment of inertia of the tuning fork beam section. In actual environments, the axial stress is much smaller than the material's yield strength and Euler critical buckling load. Therefore, by linearizing and expanding the above equation using Taylor series, we can obtain:

[0062] ,

[0063] Furthermore, the frequency shift caused by external acceleration can be obtained. for:

[0064] ,

[0065] in, The mass of the central inertial mass block, Accelerate the external environment;

[0066] From the above formula, we can see that the frequency shift of the tuning fork beam Acceleration with external forces The resonant frequency shift of the output signal is directly proportional to the linear relationship, therefore, the external acceleration can be characterized by the resonant frequency shift of the output signal.

[0067] In this embodiment, when the multi-parameter resonant sensor chip is used for acceleration sensing, a pair of five-tuning-fork resonant units arranged along the Y-axis are used to detect in-plane Y-axis acceleration, and a pair of five-tuning-fork resonant units arranged along the X-axis are used to detect in-plane X-axis acceleration. For any five-tuning-fork resonant unit, an excitation signal is applied to the first input electrode to excite the five-tuning-fork resonant unit to operate in the out-of-plane reverse vibration mode, and a sensing signal is output by the first output electrode to form a dual-port resonant sensor. Acceleration sensing is achieved by the frequency offset of the sensing signal.

[0068] Taking a pair of five-tone tuning fork resonator units arranged along the Y-axis as an example, labeled as the upper resonator unit and the lower resonator unit; as follows: Figure 8 The figure shows the curves of the resonant frequencies of the two components as a function of Y-axis acceleration. As can be seen from the figure, the frequency offset of the sensing signal can effectively characterize acceleration, thus realizing acceleration sensing. Furthermore, in this embodiment, the four five-tone fork resonant units have identical geometric dimensions and boundary conditions, and therefore have similar resonant frequencies. However, the axial stresses (axial tension or axial compression) experienced by a pair of resonant units in the Y-axis or X-axis directions are opposite. Therefore, the frequency offset changes in opposite directions. By using differential signal processing, the sensitivity can be doubled, and the error caused by common-mode interference such as temperature on the frequency offset can be removed.

[0069] In this embodiment, when the multi-parameter resonant sensor chip is used for magnetic field sensing, a pair of differential alternating voltage signals of the same magnitude but opposite polarity are applied to the first and second wire loop electrode disks. These differential voltage signals will generate an alternating current of the same frequency in the Lorentz force wire loop. Assuming that there is a DC magnetic field in the Y-axis direction in space at this time, the wire loop will be subjected to a periodic Lorentz force perpendicular to the hexagonal plate surface, forming an alternating out-of-plane bending moment, which excites the resonant unit to vibrate in an out-of-plane warping vibration mode. When the in-plane Y-axis magnetic field strength is fixed, a current signal with a fixed output amplitude can be detected through the second output electrode disk. Once the magnetic field strength changes, it will act on the resonant unit in the form of a change in Lorentz force, causing a disturbance to the vibration of the resonant unit. The detection of the external magnetic field can be achieved by reading the change in the amplitude of the output current. The sensing principle of the magnetic field in the Z-axis direction is the same as that of the Y-axis.

[0070] like Figure 9The figure shows the curve of the output current of the hexagonal resonant unit of the magnetic field sensing island in this embodiment as a function of the Y-axis magnetic field strength, where the Y-axis magnetic field strength ranges from 0 mT to 80 mT. Figure 10 The figure shows the curve of the output current of the hexagonal resonant unit of the magnetic field sensing island in this embodiment as a function of the Z-axis magnetic field strength, where the Z-axis magnetic field strength ranges from 0 mT to 80 mT. Figure 9 and Figure 10 As can be seen, the high-frequency amplitude-modulated magnetic field detection mechanism and hexagonal ring resonant structure employed in this invention can effectively sense the Y-axis and Z-axis magnetic fields, and exhibit good linearity and high sensitivity within the range of 0mT to 80mT. The Y-axis magnetic field sensitivity is 1.5 uA / mT, and the Z-axis magnetic field sensitivity is 29 nA / mT. Furthermore, in this embodiment, the Lorentz force conductor is arranged along the edge of the hexagonal resonant unit, which ensures that the Lorentz force acts at the point of maximum modal displacement, thereby improving the driving efficiency of the Lorentz force. In addition, the central hollow design can significantly reduce the equivalent mass of the resonant unit, further enhancing the magnetic field sensing sensitivity.

[0071] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A multi-parameter resonant sensor chip based on a folded isolated dual-island topology, characterized in that, The dual-island topology includes: a silicon substrate (1) and an acceleration sensing island (2) and a magnetic field sensing island (3) disposed therein; The silicon substrate (1) is arranged in a shaped topology along the XOY plane, and the acceleration sensing island (2) and the magnetic field sensing island (3) are respectively suspended in two hollow areas of the silicon substrate (1); The acceleration sensing island (2) has a 90° rotationally symmetrical structure along the XOY plane, including: a central inertial mass block (21) and a five-tone fork resonator unit group (22); the central inertial mass block is located at the center of the acceleration sensing island, and the five-tone fork resonator unit group consists of four five-tone fork resonator units, and the central inertial mass block is connected to the silicon substrate through the four five-tone fork resonator units; The five-tuning-fork resonant unit includes: a first resonant silicon substrate layer (221), a first piezoelectric thin film (222), a first input electrode (223), and a first output electrode (224); the first resonant silicon substrate layer adopts a parallel five-beam tuning fork structure with the roots of both sides converging, and one root is connected to the central inertial mass block, and the other root is connected to the silicon substrate; the first piezoelectric thin film is finger-shaped and is correspondingly disposed on each beam of the first resonant silicon substrate layer; the first input electrode and the first output electrode are arranged in an interdigitated manner and are correspondingly disposed on the first piezoelectric thin film; The magnetic field sensing island (3) has a 180° rotationally symmetric structure along the XOY plane, including: a folded beam decoupling network (31) and a hexagonal resonant unit (32). The folded beam decoupling network (31) consists of a suspended frame (311) and a multi-segment double-ended folded beam group (312). The suspended frame has a square closed loop frame structure along the XOY plane. The multi-segment double-ended folded beam group consists of four multi-segment double-ended folded beams. The suspended frame is connected to the silicon substrate through the four multi-segment double-ended folded beams. The hexagonal resonant unit (32) is located at the center of the magnetic field sensing island and includes: a second resonant silicon substrate (320), a second piezoelectric thin film (321), a first Lorentz force wire loop (322), a second output electrode (323), and a second Lorentz force wire loop (324). The second resonant silicon substrate has a regular hexagonal closed ring frame structure along the XOY plane. The second resonant silicon substrate extends radially outward along three diagonal directions with six anchor beams, which connect to the suspended frame. The second piezoelectric thin film is disposed on the second resonant silicon substrate, the second output electrode is disposed on the second piezoelectric thin film, and the first Lorentz force wire loop and the second Lorentz force wire loop are disposed together on the periphery of the second piezoelectric thin film.

2. The amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology according to claim 1, characterized in that, The silicon substrate (1) has a sandwich-type composite stacked structure along the Z-axis, which includes a bottom supporting silicon layer (13), a middle buried oxide layer (12) and a highly doped conductive silicon layer (11) from bottom to top.

3. The amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology according to claim 1, characterized in that, In the five-tone fork resonant unit, the three input fingers of the first input electrode correspond to the first, third, and fifth beams of the first resonant silicon substrate, and the three input fingers are connected by interconnects; the two output fingers of the first output electrode correspond to the second and fourth beams of the first resonant silicon substrate, and the two output fingers are connected by interconnects; the first input electrode is connected to the input electrode disk (225) by interconnects, and the first output electrode is connected to the first output electrode disk (226) by interconnects; grounding electrode disks are provided on both sides of the input electrode disk and the first output electrode disk; and a first isolation oxide layer (4) is provided between the input electrode disk, the first output electrode disk and the silicon substrate, and a first isolation oxide layer is provided between all interconnects and the first resonant silicon substrate.

4. The amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology according to claim 1, characterized in that, The multi-segment double-ended folding beam has an H-shaped topology, with one end connected to the middle suspended frame and the other end connected to the silicon substrate through an anchor point.

5. The amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology according to claim 1, characterized in that, The first Lorentz force wire circuit is connected to the first wire circuit electrode disk (325) via an interconnect line. The second output electrode is connected to the second output electrode disk (326) via an interconnect line. The second Lorentz force wire circuit is connected to the second wire circuit electrode disk (327) via an interconnect line. The first wire circuit electrode disk, the second output electrode disk, and the second wire circuit electrode disk are sequentially arranged on the floating frame. Grounding electrode disks are respectively arranged on the outer side of the first wire circuit electrode disk and the second wire circuit electrode disk. Furthermore, a second isolation oxide layer (5) is arranged between the first Lorentz force wire circuit, the second Lorentz force wire circuit, and the second resonant silicon substrate. A second isolation oxide layer is arranged between the first wire circuit electrode disk, the second output electrode disk, the second wire circuit electrode disk, and the floating frame. A second isolation oxide layer is arranged between all interconnect lines and the second resonant silicon substrate.

6. The amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology according to claim 1, characterized in that, The working process of the acceleration sensing island is as follows: for any five-tone fork resonator, an excitation signal is applied to the first input electrode to excite the five-tone fork resonator to work in the out-of-plane reverse vibration mode, and an acceleration sensing signal is output by the first output electrode. The acceleration is characterized by the frequency offset of the acceleration sensing signal.

7. The amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology according to claim 6, characterized in that, In the five-tuning-fork resonator unit group, a pair of five-tuning-fork resonator units along the Y-axis direction are used to detect in-plane Y-axis acceleration, and a pair of five-tuning-fork resonator units along the X-axis direction are used to detect in-plane X-axis acceleration; and, for a pair of five-tuning-fork resonator units in the X-axis or Y-axis direction, the acceleration measurement result is obtained through signal differential processing.

8. The amplitude-frequency composite multi-parameter resonant sensor chip based on a folded isolated dual-island topology according to claim 1, characterized in that, The working process of the magnetic field sensing island is as follows: a pair of differential alternating voltage signals of the same magnitude but opposite polarity are applied to the first Lorentz force conductor loop and the second Lorentz force conductor loop to excite the hexagonal resonant unit to vibrate in the out-of-plane warping vibration mode. The magnetic field sensing signal is output through the second output electrode, and the magnetic field is characterized by the amplitude of the magnetic field sensing signal.

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