Electric field-magnetic field composite integrated resonant MEMS sensor

Abstract

The invention belongs to the technical field of micro-electro-mechanical systems (MEMS) and the technical field of electric field / magnetic field detection, and particularly provides an electric field-magnetic field composite integrated resonant MEMS sensor which is used for solving the problem that a traditional resonant MEMS sensor can only sense a single environment parameter. According to the electric field-magnetic field composite integrated resonant MEMS sensor provided by the invention, accurate measurement of a direct-current electric field in a space thickness direction (Z axis) is realized by using an out-of-plane flapping mode of a disc resonant sensing unit fixed by four T-shaped anchor points; the measurement of an out-plane Z-axis magnetic field and an in-plane X-axis magnetic field is realized through the effect of Lorentz force on a metal wire loop which is arranged on the surface of the disc resonance sensing unit and is charged with alternating current in the magnetic field; therefore, the composite integrated sensing of two parameters of an electric field and a magnetic field by the same device is realized, and the number of required sensors and the occupied area of a chip are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical fields of Micro-Electro-Mechanical Systems (MEMS) and electric field / magnetic field detection technology, and particularly provides an electric field-magnetic field composite integrated resonant MEMS sensor. Background Art

[0002] With the advent of the 5G Internet of Things (IoT) information era, the fields of intelligent transportation, smart home, smart grid, and industrial automation have developed rapidly. As the core part of IoT sensing technology, sensor technology has received extensive attention from domestic and foreign technical researchers. Among them, the demand for electromagnetic field composite detection is becoming increasingly urgent. In the smart grid, it is necessary to detect the ambient electric field around the substation and the magnetic leakage of equipment in real time to prevent faults. In the autonomous driving system of intelligent transportation, it is necessary to synchronously sense the ambient electric field (such as charging pile interference) and the geomagnetic navigation signal. In industrial scenarios, the electromagnetic interference detection of equipment such as motors and transformers plays a crucial role in energy efficiency optimization. However, traditional electric field and magnetic field sensors are difficult to meet the composite detection requirements in the above scenarios due to problems such as single function, large volume, high cost, and difficult deployment.

[0003] MEMS micro-nano processing technology is a micro-processing technology that uses basic process steps such as lithography, thin film deposition, and etching to manufacture complex three-dimensional shapes. It can achieve micron to nanometer-level precision, and at the same time, it is easy to integrate multiple sensors or actuators with integrated electronic circuits based on traditional CMOS processes on the same chip or substrate, with characteristics such as miniaturization, low power consumption, high integration, and efficient mass production. Therefore, MEMS sensors based on MEMS micro-nano processing technology have great research and application value in various application scenarios.

[0004] MEMS sensors can be classified into piezoresistive MEMS sensors, capacitive MEMS sensors, and resonant MEMS sensors according to their different sensing principles. Among them, piezoresistive MEMS sensors use the change in resistivity of semiconductor materials under stress to measure external parameters. They have low processing costs and simple structures. However, since the resistivity is greatly affected by the external temperature, complex temperature compensation circuits are often required to improve the measurement accuracy, resulting in poor environmental adaptability. Capacitive MEMS sensors usually consist of a fixed electrode and a movable electrode. When an external physical quantity acts on the movable electrode, causing a change in capacitance, the external physical quantity can be sensed by measuring the change in capacitance. They have advantages such as high dynamic response and high temperature stability. However, they often have complex mechanically movable structures, with disadvantages such as difficult mass processing and non-linear output. At the same time, a high-vacuum package is required to ensure their normal operation. Resonant MEMS sensors work based on the frequency modulation effect of the measured physical quantity on the resonant sensitive structure. Through various excitation units, the resonant sensitive structure is caused to generate mechanical vibrations, and at the same time, the pickup unit picks up the vibration signal and converts it into an electrical signal that is easy to process and detect. When the external parameter modulates the resonant state of the resonant structure, the magnitude of the measured quantity can be calculated by measuring the output frequency signal. They can directly output digital frequency signals and have characteristics such as high sensitivity, strong anti-interference ability, and low power consumption.

[0005] There are often significant differences between the sensing principles of different environmental parameters. Therefore, traditional resonant MEMS sensors can only sense a single environmental parameter, which limits the application of resonant MEMS sensors in complex working scenarios with multiple parameters. Therefore, how to achieve the multi-parameter sensing function of resonant MEMS sensors has become an important issue that researchers at home and abroad are concerned about. In response to this problem, researchers have proposed a method of integrating resonant MEMS sensors of multiple different sensing types on a single chip. However, this method requires a high level of chip processing, and at the same time, it greatly increases the number of required sensors and the chip usage area, which is not conducive to the development of resonant MEMS sensors towards low power consumption, miniaturization, and low processing costs. Summary of the Invention

[0006] The object of the present invention is to provide an electric field-magnetic field composite integrated resonant MEMS sensor in view of the problem that traditional resonant MEMS sensors can only sense a single environmental parameter. The present invention utilizes the out-of-plane flapping mode of a disk resonant sensitive unit fixed by four T-shaped anchors to achieve precise measurement of the DC electric field in the spatial thickness direction (Z-axis). At the same time, the measurement of the out-of-plane Z-axis magnetic field and the in-plane X-axis magnetic field is realized by the action of the Lorentz force on a metal wire loop with an alternating current on the surface of the disk resonant sensitive unit in a magnetic field. Thus, the present invention realizes the composite integration sensing of two parameters, electric field and magnetic field, by the same device, reducing the number of required sensors and the area occupied by the chip.

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

[0008] An electric field-magnetic field composite integrated resonant MEMS sensor, comprising: a silicon substrate and a disk resonator main body and a pad structure integrated on the silicon substrate; characterized in that:

[0009] The sensor is square along the horizontal plane (XOY plane) and has a symmetric structure along the midline (top view of the XOY plane); the silicon substrate adopts a flat structure with a hollow center and is square-ring-shaped along the horizontal plane; the disk resonator main body is disk-shaped along the horizontal plane and is suspended in the central hollow area of the silicon substrate through 4 T-shaped anchors, and each T-shaped anchor is located at the midpoint of the corresponding side; the pad structure is arranged on the silicon substrate and includes two groups of pad components, and the two groups of pad components are symmetrically arranged on both sides of the disk resonator main body and are correspondingly connected to the disk resonator main body through metal transmission lines;

[0010] The disk resonator main body includes: a heavily doped silicon layer 1, a piezoelectric thin film 2, a central electrode 3, a ground electrode 4, and a metal wire loop 5. Among them, the heavily doped silicon layer is suspended in the central hollow area of the silicon substrate through 4 T-shaped anchors 6, the piezoelectric thin film and the ground electrode are arranged on the heavily doped silicon layer, the piezoelectric thin film is located at the central position, the ground electrode adopts an annular electrode and is located outside the piezoelectric thin film, and the central electrode is arranged on the piezoelectric thin film and is located at the central position; the metal wire loop 5 is arranged along the periphery of the ground electrode 4 and is arranged on the heavily doped silicon layer 1 through a first oxidation isolation layer 15.

[0011] Further, the pad assembly includes: a first metal electrode pad 7, a first ground electrode pad 8, a second metal electrode pad 9, a second ground electrode pad 10, and a third metal electrode pad 11 arranged side by side in sequence. Among them, the second metal electrode pad is connected to the central electrode 3 through a second metal transmission line 13; the ground electrode 4 and the metal wire loop 5 are respectively provided with windows corresponding to the second metal transmission line 13. The first metal electrode pad 7 is connected to the metal wire loop 5 on the same side through a first metal transmission line 12, and the third metal electrode pad 11 is connected to the metal wire loop 5 on the same side through a third metal transmission line 14.

[0012] Furthermore, a first oxidation isolation layer 15 is provided between the first metal electrode pad 7, the second metal electrode pad 9, the third metal electrode pad 11 and the silicon substrate to achieve electrical isolation; a first oxidation isolation layer 15 is provided between the first metal transmission line 12, the second metal transmission line 13, the third metal transmission line 14 and the silicon substrate to prevent electrical signals from leaking into the silicon substrate.

[0013] Further, a second oxidation isolation layer 16 is provided horizontally through the silicon substrate to prevent the acoustic wave energy of the resonator vibration from leaking deeper into the substrate and reduce the parasitic capacitance between the resonator and the ground.

[0014] Further, the area of the central electrode is smaller than that of the piezoelectric film, and the central electrode is located in the region with the largest strain in the out-of-plane flapping mode of the disk resonator body.

[0015] Further, when the sensor operates in the electric field sensing mode, any one of the second metal electrode pads is used to form a single-port device, and the resonance frequency of the disk resonator body is measured. The offset of the resonance frequency is used as a characterization value to achieve electric field sensing.

[0016] Further, when the sensor operates in the magnetic field sensing mode, the same differential signals are applied to a pair of first metal electrode pads and a pair of third metal electrode pads respectively, and the current directions are the same; the output current of the disk resonator body is measured through the second metal electrode pad, and the amplitude of the output current is used as a characterization value to achieve magnetic field sensing.

[0017] Based on the above technical solutions, the beneficial effects of the present invention are as follows:

[0018] 1. The present invention proposes an electric field-magnetic field composite integrated resonant MEMS sensor, which realizes the mutual conversion between mechanical energy and electrical energy through a piezoelectric film. At the same time, the silicon substrate under the disk resonator body is etched, so that the substrate cannot limit the degrees of freedom of the resonator body in the thickness direction, has a high quality factor and electromechanical coupling coefficient, and the overall structure of the device has no complex movable mechanical structure, which is convenient for mass production at low cost.

[0019] 2. The present invention proposes an electric field - magnetic field composite integrated resonant MEMS sensor. By arranging metal loop wires at the edge of the disk resonator with a relatively large displacement (the place with the maximum deflection), the driving efficiency of the Lorentz force can be effectively improved and the possibility of driving other spurious modes can be reduced. At the same time, surface metal electrodes are arranged at the place with the maximum strain at the center of the disk resonator body, making the distribution of the electric field on the surface of the piezoelectric layer more uniform, improving the excitation efficiency of the resonator. By optimizing the area ratio of the central electrode to the ground electrode (circular area), it can normally excite the vibration of the resonator while ensuring a large electric field sensitivity.

[0020] 3. The present invention proposes an electric field - magnetic field composite integrated resonant MEMS sensor. Through the design of the physical structure of the resonator, the composite integration sensing of two parameters, namely the electric field and the magnetic field, is realized on the same device, reducing the number of required sensors and the area occupied by the chip. At the same time, for the sensing of the electric field and the magnetic field, frequency shift detection and output current amplitude detection are respectively adopted, greatly reducing the cross - coupling between the sensing of the two different parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a three - dimensional schematic structural diagram of the electric field - magnetic field composite integrated resonant MEMS sensor provided by the present invention;

[0022] Figure 2 is a three - dimensional exploded structural diagram of the electric field - magnetic field composite integrated resonant MEMS sensor provided by the invention;

[0023] Figure 3 is a top - view structural diagram of the electric field - magnetic field composite integrated resonant MEMS sensor provided by the present invention;

[0024] Figure 4 is a bottom - view structural diagram of the electric field - magnetic field composite integrated resonant MEMS sensor provided by the present invention;

[0025] Figure 5 is a cross - sectional view of the A - A' of the electric field - magnetic field composite integrated resonant MEMS sensor provided by the present invention;

[0026] Figure 6 is a graph showing the shift of the resonant frequency of the electric field - magnetic field composite integrated resonant MEMS sensor provided by the present invention with the change of the electric field intensity in the vertical direction (Z - axis);

[0027] Figure 7 is a graph showing the change of the output current (the current in the metal wire loop is 1 mA) of the electric field - magnetic field composite integrated resonant MEMS sensor provided by the present invention with the change of the out - of - plane (Z - axis) magnetic field intensity;

[0028] Figure 8 Graph showing the variation of the output current (the current in the metal wire loop is 1 mA) of the electric field-magnetic field composite integrated resonant MEMS sensor provided by the present invention with the in-plane (X-axis) magnetic field intensity;

[0029] Reference numerals:

[0030] 1. Heavily doped silicon layer, 2. Piezoelectric thin film, 3. Central electrode, 4. Ground electrode, 5. Metal wire loop, 6. T-shaped anchor, 7. First metal electrode disk, 8. First ground electrode disk, 9. Second metal electrode disk, 10. Second ground electrode disk, 11. Third metal electrode disk, 12. First metal transmission line, 13. Second metal transmission line, 14. Third metal transmission line, 15. First oxidation isolation layer, 16. Second oxidation isolation layer. Detailed implementation manners

[0031] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention. For ease of understanding, the professional technical terms appearing in this text will be explained first:

[0032] Resonant frequency: When a periodic external force drives the system to generate the maximum amplitude vibration, the corresponding characteristic frequency is called the resonant frequency; in this state, the system exhibits the minimum impedance characteristic and can achieve the most efficient energy transmission, and its value mainly depends on the material properties and geometric configurations of the resonator.

[0033] Quality factor Q: This parameter characterizes the energy maintenance ability of the resonator and is quantitatively expressed as the ratio of the total energy stored in a single cycle to the energy loss; the weaker the system damping effect, the more significant the corresponding quality factor value.

[0034] Direct piezoelectric effect: When a mechanical stress in a specific direction acts on a piezoelectric body, a physical phenomenon in which spontaneous polarization is formed inside the material and bound charges of opposite signs are accumulated on the opposite surfaces.

[0035] Inverse piezoelectric effect: The coupling effect in which a piezoelectric material generates a controllable mechanical deformation under the excitation of an alternating electric field, and the deformation amplitude is directly controlled by the external electric field intensity parameter.

[0036] Acoustic impedance: A physical parameter that characterizes the blocking effect of a medium on the propagation of sound waves, and its numerical difference determines the acoustic energy distribution characteristics at the interface; when a sound wave passes through the interface of media with a sudden change in impedance, significant wavefront reflection and transmission behaviors will be triggered.

[0037] Elastic modulus: A core mechanical index that describes the resistance of a material to deformation within the elastic domain. Its physical essence is reflected as the linear proportionality coefficient of the stress-strain relationship within the material.

[0038] Example 1

[0039] This example provides an electric field-magnetic field composite integrated resonant MEMS sensor, the structure of which is as Figures 1 to 5 shown, including: a silicon substrate and a disk resonator main body and a pad structure integrated on the silicon substrate; the electric field-magnetic field composite integrated resonant MEMS sensor is square along the horizontal plane (XOY plane) and has a symmetric structure along the median line (top view of the XOY plane); the silicon substrate adopts a flat structure with a hollow center and is square-ring-shaped along the horizontal plane; the disk resonator main body is disk-shaped along the horizontal plane and is suspended in the central hollow area of the silicon substrate through 4 T-shaped anchors, and each T-shaped anchor is located at the midpoint of the corresponding side; the pad structure is arranged on the silicon substrate and includes two groups of pad components, and the two groups of pad components are symmetrically arranged on both sides of the disk resonator main body and are correspondingly connected to the disk resonator main body through metal transmission lines.

[0040] Furthermore, the disk resonator main body includes: a heavily doped silicon layer 1, a piezoelectric thin film 2, a central electrode 3, a ground electrode 4, and a metal wire loop 5. Among them, the heavily doped silicon layer 1 is suspended in the central hollow area of the silicon substrate through 4 T-shaped anchors 6, the piezoelectric thin film 2 and the ground electrode 4 are arranged on the heavily doped silicon layer 1, the piezoelectric thin film 2 is located at the central position, the ground electrode 4 adopts an annular electrode and is located outside the piezoelectric thin film 2, and the central electrode 3 is arranged on the piezoelectric thin film 2 and is located at the central position; the metal wire loop 5 is arranged along the periphery of the ground electrode 4 and is arranged on the heavily doped silicon layer 1 through a first oxidation isolation layer 15.

[0041] Even further, the pad component includes: a first metal electrode disk 7, a first ground electrode disk 8, a second metal electrode disk 9, a second ground electrode disk 10, and a third metal electrode disk 11 arranged side by side in sequence. Among them, the second metal electrode disk 9 is connected to the central electrode 3 through a second metal transmission line 13; the ground electrode 4 and the metal wire loop 5 respectively open windows corresponding to the second metal transmission line 13 (that is: the ground electrode 4 and the metal wire loop 5 correspondingly form two semi-circular structures), the first metal electrode disk 7 is connected to the metal wire loop 5 on the same side through a first metal transmission line 12, and the third metal electrode disk 11 is connected to the metal wire loop 5 on the same side through a third metal transmission line 14.

[0042] Furthermore, a first oxidation isolation layer 15 is provided between the first metal electrode disk 7, the second metal electrode disk 9, the third metal electrode disk 11 and the silicon substrate to achieve electrical isolation; a first oxidation isolation layer 15 is provided between the first metal transmission line 12, the second metal transmission line 13, the third metal transmission line 14 and the silicon substrate to prevent electrical signals from leaking into the silicon substrate.

[0043] Furthermore, a second oxidation isolation layer 16 is provided horizontally through the silicon substrate to prevent the acoustic wave energy of the resonator vibration from leaking deeper into the substrate and reduce the parasitic capacitance between the resonator and the ground.

[0044] In addition, the first and second oxidation isolation layers are silicon dioxide layers with a thickness of 0.3 μm to 1.5 μm; the piezoelectric film includes but is not limited to LiNbO3, LiTaO3, AlN, PVDF, ZnO, PZT and other piezoelectric materials with a thickness of 0.1 μm to 1 μm; the metal electrodes, metal electrode disks, metal wire loops, and metal transmission lines are made of metals such as aluminum, silver, gold, copper, nickel or platinum with a thickness of 0.2 μm to 2 μm.

[0045] In terms of the working principle:

[0046] The present invention provides an electric field - magnetic field composite integrated resonant MEMS sensor. The disk resonator body is located above the hollowed - out area of the silicon substrate, and from bottom to top are a heavily doped silicon layer, a piezoelectric film, and a metal surface electrode. The piezoelectric film is located above the heavily doped silicon layer. The heavily doped silicon layer is a silicon layer region with high conductivity doped on the surface of the silicon substrate through an ion implantation process. The piezoelectric film is a piezoelectric material film deposited by a vacuum sputtering coating method; the metal surface electrode includes a central electrode located at the center of the piezoelectric film and a ground electrode surrounding the central electrode in a circular shape. Both the central electrode and the ground electrode are respectively deposited above the piezoelectric film and above the heavily doped silicon layer through a vacuum evaporation process method. And the area of the central electrode is smaller than that of the piezoelectric film; and by designing the area of the central electrode covering the piezoelectric film, it is ensured that the central electrode is located in the region with the maximum strain in the out - of - plane flapping mode of the disk resonator, so that the working mode of the resonator can be excited while exposing a larger piezoelectric film to improve the sensing sensitivity to the electric field.

[0047] The metal wire loop is symmetrically distributed about the central axis of the disk resonator body. The metal loop wire is arranged at the edge of the disk resonator with a larger displacement (the place with the maximum deflection), which can effectively improve the driving efficiency of the Lorentz force and reduce the possibility of driving other spurious modes.

[0048] The disc resonator body is connected to the surrounding silicon substrate through 4 T-shaped silicon anchors. By using 4 anchors, the vibration suppression effect of the rigid silicon substrate on the disc resonator is reduced. At the same time, by utilizing the acoustic impedance difference between the disc resonator and air, the acoustic wave propagating to the edge of the resonator is reflected back into the resonator, improving the quality factor (Q value) and vibration amplitude of the resonator.

[0049] In the disc resonator body, setting a grounding electrode between the metal wire loop and the central electrode can effectively prevent the electrical signal in the metal wire loop from being coupled to the central electrode through parasitic capacitance, interfering with the output charge signal and thus affecting the sensing accuracy.

[0050] The present invention is implemented using a piezoelectric thin film on silicon (TPoS) structure. Its unique heavily doped silicon-based bottom layer has good conductivity and can be used as a bottom electrode. In the present invention, it is used as a ground plane. The resonator using the TPoS structure is a device that can displace itself (free vibration) or be forced to displace (forced vibration). It mainly consists of a micro-mechanical structure and an electromechanical sensor. The excitation structure converts the external excitation voltage signal into the strain of the piezoelectric thin film through the inverse piezoelectric effect, and the pickup structure collects the charges generated by the piezoelectric thin film through the direct piezoelectric effect, forming a sensing signal current during the periodic conversion of electrical energy and mechanical energy.

[0051] As Figure 6 shown, the sensing function of the present invention for the Z-axis electric field is realized by detecting the resonance frequency shift of the disc resonator body. Its working principle in the electric field sensing mode is as follows: For a micro-mechanical structure, it has an inherent resonance frequency, and the magnitude of this frequency is determined by the material properties and geometric shape of the micro-mechanical structure itself. The disc resonator in the present invention operates in the out-of-plane flapping mode (thickness vibration mode), and the expression for its inherent resonance frequency f0 is:

[0052]

[0053] where, V p is the velocity of the acoustic wave in the material, d is the thickness of the material, V p is usually determined by the elastic modulus and stiffness of the material. Considering that the resonator using the TPoS structure is a composite structure of multiple layers of materials, its vibration frequency may be affected by the elastic modulus and mass of each layer. Therefore, the total resonance frequency is determined by the equivalent elastic modulus E eff and the equivalent density ρ eff of the resonator as a whole;

[0054] Taking aluminum nitride as an example, when an electric field E zWhen there is an electric field, aluminum nitride will generate strain S0 due to the inverse piezoelectric effect, and its expression is:

[0055] S0 = d 33 E z

[0056] where d 33 is the piezoelectric coefficient of aluminum nitride in the thickness direction;

[0057] The strain S0 will cause a change in the thickness h AlN of the piezoelectric film, thus changing the propagation time t AlN of the acoustic wave in the aluminum nitride layer. The change in the thickness of the piezoelectric film Δh AlN and the changed propagation time t ′ AlN of the aluminum nitride layer are expressed as:

[0058] Δh AlN = h AlN d 33 E z

[0059]

[0060] where V AlN is the sound velocity of the acoustic wave in the aluminum nitride layer;

[0061] Therefore, the total propagation time t total becomes t ′ total :

[0062]

[0063] At this time, the new resonance frequency f1 of the resonator is:

[0064]

[0065] It can be found from the above formula that there is a linear offset relationship between the externally applied Z-axis electric field strength and the frequency response of the disk resonator. Therefore, by detecting the offset of the resonance frequency, the magnitude of the measured electric field strength can be deduced.

[0066] Such as Figure 6 、 Figure 7As shown, the sensing of the out-of-plane (Z-axis) magnetic field and the in-plane (X-axis) magnetic field of the present invention is achieved by detecting the amplitude of the output current of the resonator. When the disk resonator in the present invention operates in the magnetic field sensing mode, its working principle is as follows: The disk resonator is driven by the Lorentz force, which is generated by the interaction between the excitation current applied in the metal wire loop and the external magnetic field. When working, a differential AC voltage is applied through the first metal electrode disk and the second metal electrode disk to generate an AC current in the metal wire loop, and further generate the Lorentz force to drive the disk resonator to vibrate. At this time, the central electrode can collect the charges generated by the piezoelectric film due to the piezoelectric effect, and finally modulate them into the form of current for output. The change in the external magnetic field strength will affect the magnitude of the Lorentz force, and finally the measurement of the external magnetic field can be realized by detecting the change in the amplitude of the output current.

[0067] By optimizing the covering position of the central electrode and its area ratio with the grounding electrode (circular area), the present invention enables it to effectively excite the disk resonator to vibrate in the out-of-plane flapping mode while also exposing a larger area of the piezoelectric film to increase the strain caused by the external electric field, improving the excitation efficiency and electric field sensitivity of the resonator. When the resonator measures the electric field in the space Z-axis, to prevent the Lorentz force generated by the space magnetic field from affecting the resonator, the influence of the magnetic field on the electric field measurement can be isolated by controlling the magnitude of the AC current in the metal wire loop. When there is no alternating current in the metal wire loop, the resonator will not be affected by the external magnetic field, ensuring the accuracy of the electric field measurement. And the measurement of the two external parameters is realized based on two different principles of frequency shift and amplitude change respectively, reducing the possibility of cross-coupling of the two different sensing parameters.

[0068] The present invention etches the substrate silicon under the main body of the disk resonator through the deep reactive ion etching process, and only connects to the substrate silicon through four T-shaped anchors around the resonator. Compared with the traditional rectangular anchors, the T-shaped anchors can extend the transmission path of the vibration energy, increase the reflection and scattering of the sound waves, make the energy more effectively concentrated inside the resonator. At the same time, the branch design of the T-shaped anchors can disperse the stress concentration problem in the processing process, making the resonator have better mechanical stability.

[0069] In summary, the electric field-magnetic field composite integrated resonant MEMS sensor proposed by the present invention realizes the function of simultaneously sensing the electric field and the magnetic field by a single device through physical structure design. Without the need to process complex mechanical movable structures, it also has high device integration and device sensitivity, avoiding the problems of large volume and single function of traditional electric field and magnetic field sensors.

[0070] The above are only specific embodiments of the present invention. Any feature disclosed in this specification, unless specifically stated, can be replaced by other equivalent or alternative features with similar purposes; all the disclosed features, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any manner.

Claims

1. An electric field - magnetic field composite integrated resonant MEMS sensor, comprising: A silicon substrate and a disk resonator body and a pad structure integrated on the silicon substrate; characterized in that: The sensor is square along the horizontal plane (XOY plane) and symmetrical along the midline (top view of the XOY plane); the silicon substrate adopts a flat plate structure with a hollow center and is square ring-shaped along the horizontal plane; the disk resonator body is disk-shaped along the horizontal plane and is suspended in the central hollow area of ​​the silicon substrate through four T-shaped anchor points, each T-shaped anchor point is located at the midpoint of the corresponding side; the pad structure is arranged on the silicon substrate, including two groups of pad assemblies, the two groups of pad assemblies are symmetrically arranged on both sides of the disk resonator body and are correspondingly connected to the disk resonator body through metal transmission lines; The disk resonator body comprises: a heavily doped silicon layer (1), a piezoelectric film (2), a central electrode (3), a grounding electrode (4) and a metal wire loop (5), wherein the heavily doped silicon layer is suspended in the central hollow area of ​​the silicon substrate through four T-shaped anchor points (6), the piezoelectric film and the grounding electrode are arranged on the heavily doped silicon layer, the piezoelectric film is located at the center, the grounding electrode is a ring-shaped electrode and is located at the periphery of the piezoelectric film, and the central electrode is arranged on the piezoelectric film and is located at the center; the metal wire loop is arranged along the periphery of the grounding electrode and is arranged on the heavily doped silicon layer through a first oxide isolation layer.

2. The electric field-magnetic field composite integrated resonant MEMS sensor according to claim 1, wherein The pad assembly comprises: a first metal electrode pad (7), a first grounding electrode pad (8), a second metal electrode pad (9), a second grounding electrode pad (10) and a third metal electrode pad (11) arranged in sequence and in parallel, wherein the second metal electrode pad is connected to a central electrode via a second metal transmission line (13); windows are respectively provided in the grounding electrode and the metal wire loop corresponding to the second metal transmission line, the first metal electrode pad is connected to the metal wire loop on the same side via the first metal transmission line (12), and the third metal electrode pad is connected to the metal wire loop on the same side via a third metal transmission line (14).

3. The electric field-magnetic field composite integrated resonant MEMS sensor according to claim 2, wherein A first oxidized isolation layer (15) is provided between the first metal electrode disk, the second metal electrode disk, the third metal electrode disk and the silicon substrate; a first oxidized isolation layer (15) is provided between the metal wire loop, the first metal transmission line, the second metal transmission line, the third metal transmission line and the silicon substrate.

4. The integrated electric field-magnetic field composite resonant MEMS sensor according to claim 1, wherein A second oxide isolation layer (16) is provided in a horizontal direction through the silicon substrate.

5. The electric field-magnetic field composite integrated resonant MEMS sensor according to claim 1, wherein The area of ​​the central electrode is smaller than that of the piezoelectric film, and the central electrode is located in the region with the maximum strain in the out-of-plane flapping mode of the disk resonator body.

6. The electric field-magnetic field composite integrated resonant MEMS sensor according to claim 1, wherein When the sensor works in the electric field sensing mode, any second metal electrode disk is used to form a single-port device, the resonant frequency of the disk resonator body is measured, and the offset of the resonant frequency is used as a characterization value to achieve electric field sensing.

7. The electric field-magnetic field composite integrated resonant MEMS sensor according to claim 1, wherein When the sensor works in the magnetic field sensing mode, a pair of first metal electrode disks and a pair of third metal electrode disks respectively apply the same differential signal, and the current direction is the same; the output current of the disk resonator body is measured by the second metal electrode disk, and the amplitude of the output current is used as the characterization value to realize magnetic field sensing.

Images