Displacement control system of electromagnetic MEMS actuator integrated with magnetic sensor and preparation method

Abstract

The invention discloses a displacement control system of an electromagnetic MEMS actuator integrated with a magnetic sensor and a preparation method, and relates to the technical field of electromagnetic MEMS actuators. The displacement control system can comprise a coil driving module, an electromagnetic MEMS actuator, at least one magnetic sensor and a signal processing unit. The electromagnetic MEMS actuator comprises a permanent magnet and a micro-motion structure. The permanent magnet is driven by the coil driving module to move; the micro-motion structure is fixedly connected with the permanent magnet; the at least one magnetic sensor and the micro-motion structure are arranged on the same substrate surface, and the at least one magnetic sensor is arranged on one side of the micro-motion structure and is used for collecting a magnetic displacement signal generated when the permanent magnet moves so as to generate an electric signal according to the magnetic displacement signal; and the signal processing unit generates a control signal according to the electric signal and transmits the control signal to the coil driving module, so that the coil driving module controls the permanent magnet to move according to the control signal so as to control the displacement of the micro-motion structure. By integrating the magnetic sensor and the micro-motion structure, the displacement control system has the capacity of closed-loop control of the displacement of the micro-motion structure.

Description

Technical Field

[0001] This application relates to the technical field of electromagnetic MEMS actuators. Specifically, it relates to a displacement control system and a preparation method for an electromagnetic MEMS actuator integrated with a magnetic sensor. Background Art

[0002] Under normal circumstances, the electromagnetic drive structure of an electromagnetic MEMS device consists of two parts: one is a permanent magnet located on the elastic frame of the actuator. The permanent magnet can provide a driving force for the movement of the electromagnetic MEMS actuator under the action of an external magnetic field. The other part is a coil drive module. A current flows through the coil of the coil drive module and interacts with the magnetic field generated by the permanent magnet to drive the movement of the elastic frame of the electromagnetic MEMS actuator.

[0003] Among them, the position detection of the electromagnetic MEMS actuator is one of the key parts in the closed-loop control system of the electromagnetic MEMS actuator, which directly affects the control accuracy and working performance of the electromagnetic MEMS actuator.

[0004] At present, the position detection of electromagnetic MEMS actuators includes information acquisition means such as high-resolution cameras, laser displacement sensors, and eddy current sensors. However, devices such as high-resolution cameras and laser displacement sensors are difficult to be compatible with the micro-motion structure of electromagnetic MEMS actuators in terms of size and volume. Although eddy current sensors may be miniaturized and integrated, they still have disadvantages such as high excitation frequency and high power consumption.

[0005] The content of the background art part is only the technology known to the applicant and does not of course represent the prior art in this field. Summary of the Invention

[0006] This application aims to provide a displacement control system and a preparation method for an electromagnetic MEMS actuator integrated with a magnetic sensor to solve the problems that devices such as high-resolution cameras and laser displacement sensors are difficult to be compatible with the micro-motion structure of electromagnetic MEMS actuators in terms of size and volume, and that eddy current sensors require high excitation frequency and high power consumption.

[0007] According to one aspect of the present application, the present application provides a displacement control system for an electromagnetic MEMS actuator integrated with a magnetic sensor. The displacement control system may include a coil driving module, an electromagnetic MEMS actuator, at least one magnetic sensor, and a signal processing unit. The electromagnetic MEMS actuator includes a permanent magnet and a micro-moving structure. The permanent magnet moves under the drive of the coil driving module; the micro-moving structure is fixedly connected to the permanent magnet; at least one magnetic sensor and the micro-moving structure are disposed on the same substrate surface and on one side of the micro-moving structure to collect the magnetic displacement signal generated when the permanent magnet moves, so as to generate an electrical signal according to the magnetic displacement signal; the signal processing unit receives the electrical signal, generates a control signal according to the electrical signal, and transmits the control signal to the coil driving module, so that the coil driving module controls the movement of the permanent magnet according to the control signal to control the displacement of the micro-moving structure.

[0008] According to some embodiments of the present application, the displacement control system further includes a support portion. One end of the support portion is fixedly connected to the coil driving module, and the other end of the support portion is fixedly connected to the micro-moving structure to support the micro-moving structure.

[0009] According to some embodiments of the present application, the micro-moving structure includes a micro-moving platform and a motion coupling portion. The micro-moving platform is fixedly connected to the permanent magnet; one end of the motion coupling portion is elastically connected to the micro-moving platform; when the coil driving module receives a control signal, the coil driving module generates a driving magnetic field according to the control signal; the permanent magnet generates motion under the action of the driving magnetic field, so that the magnetic sensor collects the magnetic displacement signal generated by the motion of the permanent magnet; when the permanent magnet moves, the permanent magnet drives the movement of the micro-moving platform.

[0010] According to some embodiments of the present application, the signal processing unit includes a signal processor and a position controller. The signal processor generates position data according to the electrical signal; the position controller generates a control signal according to the position data.

[0011] According to some embodiments of the present application, the displacement control system includes at least two magnetic sensors, and the at least two magnetic sensors are disposed on different sides of the micro-moving structure to collect magnetic displacement signals in multiple directions generated when the permanent magnet moves.

[0012] According to some embodiments of the present application, the motion coupling portion includes a first elastic member, a first coupling member, a second elastic member, and a second coupling member. One end of the first elastic member is connected to the micro-moving platform; one end of the first coupling member is connected to one end of the first elastic member; one end of the second elastic member is connected to the other end of the first coupling member; one end of the second coupling member is connected to the other end of the second elastic member; the magnetic sensor is disposed on the upper surface of the second coupling member.

[0013] According to one aspect of the present application, the present application provides a method for fabricating an electromagnetic MEMS actuator integrated with a magnetic sensor. The fabrication method includes: a step of fabricating a magnetic sensor; a step of fabricating a micro-motion structure of the electromagnetic MEMS actuator; and connecting a permanent magnet and the micro-motion structure to obtain an electromagnetic MEMS actuator integrated with a magnetic sensor. The step of fabricating a magnetic sensor includes: fabricating a first passivation layer on a substrate; disposing a magnetic thin film layer group at a first position of the first passivation layer, wherein the magnetic thin film layer group includes a first electrode layer, a magnetic thin film layer, and a second electrode layer, the magnetic thin film layer is disposed between the first electrode layer and the second electrode layer, and the first electrode layer is in contact with the first passivation layer; etching the magnetic thin film layer group to obtain a target magnetic thin film layer group with a first preset shape to obtain a magnetic sensor; The step of fabricating the micro-motion structure of the electromagnetic MEMS actuator includes: etching the substrate and the first passivation layer at a second position of the substrate to obtain a micro-motion structure with a second preset shape; wherein the first position is located on one side of the second position.

[0014] According to some embodiments of the present application, after etching the magnetic thin film layer group to obtain a target magnetic thin film layer group with a first preset shape to obtain a magnetic sensor, the step of fabricating a magnetic sensor further includes: fabricating a second passivation layer on the substrate; etching the second passivation layer to obtain a first window of the first electrode layer and a second window of the second electrode layer; disposing a lead layer on the first window to obtain a first metal lead layer of the first electrode layer, and disposing a lead layer on the second window to obtain a second metal lead layer of the second electrode to obtain a magnetic sensor with a second passivation layer. Etching the first passivation layer and the substrate at a second position of the substrate to obtain a micro-motion structure with a second preset shape includes: etching the second passivation layer, the first passivation layer, and the substrate at the second position to obtain a micro-motion structure with a second preset shape.

[0015] According to some embodiments of the present application, after disposing a lead layer on the first window to obtain a first metal lead layer of the first electrode layer, and disposing a lead layer on the second window to obtain a second metal lead layer of the second electrode to obtain a magnetic sensor with a second passivation layer, the step of fabricating a magnetic sensor further includes: applying an annealing magnetic field with a preset magnetic field and an annealing temperature with a preset temperature to the magnetic sensor to obtain a magnetic thin film layer with magnetic domains in a preset direction.

[0016] According to some embodiments of the present application, etching the magnetic thin film layer group to obtain a target magnetic thin film layer group with a first preset shape to obtain a magnetic sensor includes: etching the magnetic thin film layer group to obtain at least two magnetic thin film layer groups with a first preset shape to obtain at least two magnetic sensors.

[0017] Through the above embodiments, the present application can integrally form in-situ the micro-motion structure of a magnetic sensor and an electromagnetic MEMS actuator on the substrate of the same wafer, such that the magnetic sensor can collect the magnetic displacement signal during the movement of the permanent magnet. The present application can generate an electrical signal based on the magnetic displacement signal. The present application can generate a control signal based on the electrical signal. The present application can transmit the control signal to the coil driving module to control the displacement of the micro-motion structure.

[0018] The present application can integrate a magnetic sensor and a micro-motion structure, enabling the displacement control system of the present application to have the ability to perform closed-loop control of the displacement of the micro-motion structure. The magnetic thin film layer in the present application is a tunneling magnetoresistance junction (TMR). The magnetic displacement signal is collected by a TMR sensor. The TMR sensor has the advantages of high sensitivity, can improve the control accuracy of the displacement control system of the present application, and the TMR sensor does not require a high excitation frequency and high power consumption.

[0019] The present application can integrate the micro-motion structure of a magnetic sensor and an electromagnetic MEMS actuator on the substrate of the same wafer. The displacement control system of the present application has a simple structure, realizes miniaturization and high integration, and is suitable for application scenarios with limited space. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 FIG. 1 shows a schematic structural diagram of a displacement control system according to an embodiment of the present application; Figure 2 FIG. 2 shows a top view structural diagram of a coil driving module, an electromagnetic MEMS actuator, a magnetic sensor, and a support part according to an embodiment of the present application; Figure 3 FIG. 3 shows a side view structural diagram of a coil driving module, an electromagnetic MEMS actuator, a magnetic sensor, and a support part according to an embodiment of the present application; Figure 4 FIG. 4 shows a structural diagram of a magnetic sensor according to an embodiment of the present application; Figure 5 FIG. 5 shows another schematic structural diagram of a displacement control system according to an embodiment of the present application; Figure 6 FIG. 6 shows a schematic flow diagram of a preparation method 2000 according to an embodiment of the present application; Figure 7 FIG. 7 shows a schematic flow diagram of step S100 according to an embodiment of the present application; Figure 8 Another schematic flowchart of step S100 according to an embodiment of the present application is shown; Figure 9 Another schematic flowchart of step S100 according to an embodiment of the present application is shown.

[0022] Description of reference numerals: Displacement control system 1000.

[0023] Coil driving module 1100; electromagnetic MEMS actuator 1200; magnetic sensor 1300; signal processing unit 1400; support part 1500.

[0024] Permanent magnet 1210; micro motion structure 1220.

[0025] Micro motion platform 1221; motion coupling part 1222.

[0026] Signal processor 1410; position controller 1420.

[0027] PID controller 1421; signal generator 1422; PWM modulator 1423.

[0028] First elastic member 12221; first coupling member 12222; second elastic member 12223; second coupling member 12224.

[0029] Magnetic thin film layer group 1310.

[0030] First electrode layer 1311; magnetic thin film layer 1312; second electrode layer 1313; first metal lead layer 1314; second metal lead layer 1315; first passivation layer 1316; second passivation layer 1317. Detailed implementation manners

[0031] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Identical reference numerals in the figures denote identical or similar parts, and thus their repetitive description will be omitted.

[0032] The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. may be used. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0033] Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or other steps or units inherent to these processes, methods, products, or devices.

[0034] The terms "first", "second", etc. in the description and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order.

[0035] The technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of this application.

[0036] The English involved in this application, its full English name, and the corresponding Chinese interpretations are as follows: TMR, Tunneling Magnetoresistance Sensor, tunnel magnetoresistance sensor.

[0037] PID, Proportional-Integral-Derivative Controller, proportional-integral-derivative controller.

[0038] MEMS, Micro-Electro-Mechanical System, micro-electromechanical storage system.

[0039] PECVD, Plasma-Enhanced Chemical Vapor Deposition, plasma-enhanced chemical vapor deposition.

[0040] PWM, Pulse-Width Modulation, pulse width modulation.

[0041] According to one aspect of the present application, the present application provides a displacement control system for an electromagnetic MEMS actuator integrated with a magnetic sensor. Refer to Figure 1 , the displacement control system 1000 may include a coil driving module 1100, an electromagnetic MEMS actuator 1200, at least one magnetic sensor 1300, and a signal processing unit 1400.

[0042] According to an exemplary embodiment, the coil driving module 1100 may be a device that converts electrical energy into mechanical energy by electromagnetic principles.

[0043] Refer to Figure 2 , the electromagnetic MEMS actuator 1200 includes a permanent magnet 1210 and a micro motion structure 1220.

[0044] According to an exemplary embodiment, the permanent magnet 1210 may move under the drive of the coil driving module 1100. The permanent magnet 1210 may be disposed at a position close to the coil driving module 1100, which can improve the response speed of the permanent magnet 1210 to the coil driving module 1100 and enhance the driving force generated by the coil driving module 1100 on the permanent magnet 1210. The permanent magnet 1210 may be movably connected to the coil driving module 1100.

[0045] According to an exemplary embodiment, the micro motion structure 1220 is fixedly connected to the permanent magnet 1210. The micro motion structure 1220 may be disposed on the surface of the substrate of the wafer.

[0046] Exemplarily, the substrate of the wafer may be a silicon substrate. The micro motion structure 1220 may be prepared by semiconductor manufacturing processes to etch the silicon substrate, and the etched silicon frame forms the micro motion structure 1220.

[0047] According to an exemplary embodiment, the magnetic sensor 1300 and the micro motion structure 1220 are disposed on the same substrate surface, and the magnetic sensor 1300 is disposed on one side of the micro motion structure 1220. The magnetic sensor 1300 may collect the magnetic displacement signal generated when the permanent magnet 1210 moves, and the magnetic sensor 1300 may convert the magnetic displacement signal into an electrical signal. The magnetic displacement signal may be a magnetic field change signal when the permanent magnet 1210 generates displacement. The magnetic sensor 1300 may perform processing such as magnetoresistive conversion and amplification on the magnetic displacement signal to convert the magnetic displacement signal into an electrical signal.

[0048] Exemplarily, the magnetic sensor 1300 may be a TMR sensor. The TMR sensor may be a sensor that measures the magnetic field using the quantum tunneling effect. The TMR sensor has a high magnetic field sensitivity, can detect very weak magnetic field changes, and convert the magnetic field change signal into an electrical signal for output.

[0049] For example, refer to Figure 4, the magnetic sensor 1300 may include a first passivation layer 1316 and a magnetic thin film layer group 1310. The magnetic thin film layer group 1310 includes a first electrode layer 1311, a magnetic thin film layer 1312, and a second electrode layer 1313. The magnetic thin film layer 1312 is disposed between the first electrode layer 1311 and the second electrode layer 1313. The first electrode layer 1311 is in contact with the first passivation layer 1316.

[0050] The substrate may be silicon, and the first passivation layer 1316 may be silicon dioxide (SiO2). The first electrode layer 1311 and the second electrode layer 1313 may be metal layers such as chromium (Cr) or ruthenium (Ru). The magnetic thin film layer 1312 may be a tunneling magnetoresistance junction (TMR). For example, the magnetic thin film layer 1312 may be a multi-layer film structure such as cobalt iron boron / magnesium oxide / cobalt iron boron (CoFeB / MgO / CoFeB), platinum manganese / cobalt iron / ruthenium / cobalt iron boron / magnesium oxide / cobalt iron boron (PtMn / CoFe / Ru / CoFeB / MgO / CoFeB), nickel iron / cobalt iron boron / magnesium oxide / cobalt iron boron (NiFe / CoFeB / MgO / CoFeB), cobalt iron boron / magnesium oxide / cobalt iron boron / magnesium oxide / cobalt iron boron (CoFeB / MgO / CoFeB / MgO / CoFeB), cobalt iron boron / magnesium oxide / cobalt iron boron / ruthenium / cobalt iron boron (CoFeB / MgO / CoFeB / Ru / CoFeB), etc.

[0051] The first electrode layer 1311 may serve as a bottom electrode. The lower surface of the magnetic thin film layer 1312 is in contact with the upper surface of the first electrode layer 1311, and the magnetic thin film layer 1312 is sensitive to magnetic change signals. The lower surface of the second electrode layer 1313 may be in contact with the upper surface of the magnetic thin film layer 1312, and the second electrode layer 1313 may serve as a top electrode. The first electrode layer 1311 and the second electrode layer 1313 may output the magnetic change signals collected by the magnetic thin film layer 1312.

[0052] See Figure 4 , the magnetic sensor 1300 may further include a first metal lead layer 1314, a second metal lead layer 1315, and a second passivation layer 1317. The first metal lead layer 1314 may be in contact with the first electrode layer 1311 such that the first metal lead layer 1314 can be electrically connected to the first electrode layer 1311. The second metal lead layer 1315 may be in contact with the second electrode layer 1313 such that the second metal lead layer 1315 can be electrically connected to the second electrode layer 1313. The first metal lead layer 1314 and the second metal lead layer 1315 may output the magnetic change signals collected by the magnetic thin film layer 1312.

[0053] The second passivation layer 1317 can isolate and protect the sidewalls of the magnetic thin film layer group 1310. The second passivation layer 1317 can be SiO2. The thickness of the second passivation layer 1317 can cover the sidewalls and the upper surface of the magnetic thin film layer group 1310 (the first electrode layer 1311, the magnetic thin film layer 1312, and the second electrode layer 1313).

[0054] According to an exemplary embodiment, the signal processing unit 1400 receives an electrical signal, and the signal processing unit 1400 generates a control signal according to the electrical signal. The control signal can be a signal for controlling the displacement of the micro-motion structure 1220.

[0055] For example, the signal processing unit 1400 can generate position data according to the electrical signal through a positioning algorithm, and the signal processing unit 1400 generates a control signal from the position data. The control signal can be a direct current signal with a constant current value or an alternating current signal with a fixed amplitude.

[0056] Exemplarily, the positioning algorithm can be a fitting positioning algorithm, a neural network magnetic field mapping positioning algorithm based on a neural network model, etc.

[0057] The signal processing unit 1400 transmits the control signal to the coil driving module 1100, so that the coil driving module 1100 controls the movement of the permanent magnet 1210 according to the control signal to control the displacement of the micro-motion structure 1220.

[0058] For example, the signal processing unit 1400 transmits a direct current signal (or an alternating current signal) to each coil in the coil driving module 1100. Under the action of the direct current signal (or the alternating current signal), the magnetic field of the coil driving module 1100 changes. The permanent magnet 1210 generates a displacement under the action of the changing magnetic field of the coil driving module 1100, thereby driving the micro-motion structure 1220 to generate a displacement. The magnetic sensor 1300 can continue to collect the magnetic displacement signal generated when the permanent magnet 1210 moves, thereby forming a closed-loop control of the displacement of the micro-motion structure 1220, so that the micro-motion structure 1220 can move to a specified position.

[0059] Through the above embodiments, the present application can integrally integrate the magnetic sensor and the micro-motion structure of the electromagnetic MEMS actuator in-situ on the substrate of the same wafer, so that the magnetic sensor can collect the magnetic displacement signal when the permanent magnet moves. The present application can generate an electrical signal through the magnetic displacement signal. The present application can generate a control signal through the electrical signal. The present application can control the displacement of the micro-motion structure by transmitting the control signal to the coil driving module.

[0060] This application can integrate a magnetic sensor and a micro-motion structure, enabling the displacement control system of this application to have the ability to close-loop control the displacement of the micro-motion structure. The magnetic thin film layer in this application is a tunneling magnetoresistance junction (TMR). The magnetic displacement signal is collected by the TMR sensor. The TMR sensor has the advantages of high sensitivity, which can improve the control accuracy of the displacement control system of this application, and the TMR sensor does not require a high excitation frequency and high power consumption.

[0061] This application can in-situ integrate the micro-motion structure of the magnetic sensor and the electromagnetic MEMS actuator on the substrate of the same wafer. The structure of the displacement control system of this application is simple, realizing miniaturization and high integration, and is suitable for application scenarios with limited space.

[0062] Optionally, referring to Figure 2 and Figure 3 , the displacement control system 1000 further includes a support part 1500. One end of the support part 1500 is fixedly connected to the coil driving module 1100, and the other end of the support part 1500 is fixedly connected to the micro-motion structure 1220. The support part 1500 can support the micro-motion structure 1220, making the displacement of the micro-motion structure 1220 more stable.

[0063] Optionally, referring to Figure 2 and Figure 3 , the micro-motion structure 1220 includes a micro-motion platform 1221 and a motion coupling part 1222.

[0064] According to the exemplary embodiment, the micro-motion platform 1221 is fixedly connected to the permanent magnet 1210. For example, the permanent magnet 1210 can be adhered to the lower surface of the micro-motion platform 1221 by nano glue. When the permanent magnet 1210 moves, the permanent magnet 1210 drives the micro-motion platform 1221 to move.

[0065] One end of the motion coupling part 1222 is elastically connected to the micro-motion platform 1221. The other end of the motion coupling part 1222 is fixedly connected to the magnetic sensor 1300. The motion coupling part 1222 can prevent the magnetic sensor 1300 from generating displacement when the micro-motion platform 1221 is driven to move.

[0066] According to the exemplary embodiment, when the coil driving module 1100 receives a control signal, the coil driving module 1100 generates a driving magnetic field according to the control signal. The permanent magnet 1210 moves under the action of the driving magnetic field, so that the magnetic sensor 1300 collects the magnetic displacement signal generated by the movement of the permanent magnet 1210. When the permanent magnet 1210 moves, the permanent magnet 1210 drives the micro-motion platform 1221 to move.

[0067] Through the above embodiments, the present application can be elastically connected to the micro-motion platform through the motion coupling part, and the motion coupling part is fixedly connected to the magnetic sensor, so that when the micro-motion platform is driven by the permanent magnet to move, the magnetic sensor is in a stable state.

[0068] Optionally, referring to Figure 5 , the signal processing unit 1400 includes a signal processor 1410 and a position controller 1420.

[0069] According to an exemplary embodiment, the signal processor 1410 can generate position data according to the electrical signal.

[0070] Exemplarily, the signal processor 1410 can be a microprocessor. The microprocessor can receive the amplified and filtered electrical signal, and the microprocessor executes a positioning algorithm to output accurate position data according to the electrical signal.

[0071] According to an exemplary embodiment, the position controller 1420 generates a control signal according to the position data.

[0072] Exemplarily, the position controller 1420 can include a PID controller 1421, a signal generator 1422, and a PWM modulator 1423. The PID controller 1421 can generate a target position signal according to the position data. The signal generator 1422 can generate a continuous waveform (such as a sine / triangle wave) of the target position signal. The PWM modulator 1423 can modulate the amplitude and energy of the continuous waveform of the target position signal, so that the target position signal is converted into a control signal. The PWM modulator 1423 transmits the control signal to the coil driving module 1100.

[0073] Through the above embodiments, the present application can generate position data according to the electrical signal through the signal processor, and generate a control signal according to the position data through the position controller, so as to realize the digital control of the control signal.

[0074] Optionally, referring to Figure 2 , the displacement control system 1000 includes at least two magnetic sensors 1300. The at least two magnetic sensors 1300 are arranged on different sides of the micro-motion structure 1220 to collect magnetic displacement signals in multiple directions generated when the permanent magnet 1210 moves.

[0075] For example, referring to Figure 2, the fine motion structure 1220 of the electromagnetic MEMS actuator 1200 may be a rectangular structure. The displacement control system 1000 includes four magnetic sensors 1300. The four magnetic sensors 1300 may be respectively arranged around the fine motion structure 1220. The four magnetic sensors 1300 may be divided into two groups. Two magnetic sensors 1300 may collect magnetic displacement signals in the X horizontal direction in the Cartesian coordinate system, and the other two magnetic sensors 1300 may collect magnetic displacement signals in the Y horizontal direction in the Cartesian coordinate system.

[0076] Optionally, referring to Figure 2 , the motion coupling part 1222 includes a first elastic member 12221, a first coupling member 12222, a second elastic member 12223, and a second coupling member 12224.

[0077] According to the exemplary embodiment, one end of the first elastic member 12221 is connected to the fine motion platform 1221. One end of the first coupling member 12222 is connected to one end of the first elastic member 12221. One end of the second elastic member 12223 is connected to the other end of the first coupling member 12222. One end of the second coupling member 12224 is connected to the other end of the second elastic member 12223.

[0078] For example, referring to Figure 2 , the first elastic member 12221 and the second elastic member 12223 may be elastic silicon structures. The first coupling member 12222 and the second coupling member 12224 may be elastic silicon frame structures.

[0079] The magnetic sensor 1300 is arranged on the upper surface of the second coupling member. When the fine motion platform 1221 is driven to move, due to the coupling action of the first elastic member 12221, the first coupling member 12222, the second elastic member 12223, and the second coupling member 12224, the first elastic member 12221, the first coupling member 12222, and the second elastic member 12223 may be driven to move by the fine motion platform 1221, and the second coupling member 12224 may not move, so that the magnetic sensor 1300 is in a stable position.

[0080] Through the above embodiments, the present application can elastically connect the first elastic member to the fine motion platform. One end of the first coupling member is connected to one end of the first elastic member. One end of the second elastic member is connected to the other end of the first coupling member. One end of the second coupling member is connected to the other end of the second elastic member, so that when the fine motion platform is driven to move by the permanent magnet, the magnetic sensor is in a stable state.

[0081] According to an aspect of the present application, the present application provides a preparation method 2000 of an electromagnetic MEMS actuator integrated with a magnetic sensor. Referring to Figure 6, the preparation method 2000 includes steps S100 - S300.

[0082] In step S100, a magnetic sensor is prepared.

[0083] See Figure 7 , step S100 may include steps S110 - step S130.

[0084] In step S110, a first passivation layer is prepared on the substrate.

[0085] According to an exemplary embodiment, the wafer may be a silicon (Si)-based wafer, the substrate may be silicon. The first passivation layer may be silicon dioxide (SiO2).

[0086] For example, in step S110, the silicon-based wafer is cleaned successively with acetone, absolute ethanol, and deionized water. Based on the method of thermal oxidation, a layer of SiO2 with a thickness of 1um - 2um is thermally oxidized on the silicon substrate of the silicon-based wafer.

[0087] In step S120, a magnetic thin film layer group is set at a first position of the first passivation layer.

[0088] According to an exemplary embodiment, in step S120, based on the method of magnetron sputtering, a magnetic thin film layer group is sputtered on the first passivation layer. The magnetic thin film layer group is a multi-layer structure. The magnetic thin film layer group includes a first electrode layer, a magnetic thin film layer, and a second electrode layer. The magnetic thin film layer is disposed between the first electrode layer and the second electrode layer, and the first electrode layer is in contact with the first passivation layer.

[0089] The first electrode layer and the second electrode layer may be metal layers such as chromium (Cr) or ruthenium (Ru). The magnetic thin film layer may be a tunneling magnetoresistance junction (TMR). For example, the magnetic thin film layer may be a multi-layer film structure such as cobalt iron boron / magnesium oxide / cobalt iron boron (CoFeB / MgO / CoFeB), platinum manganese / cobalt iron / ruthenium / cobalt iron boron / magnesium oxide / cobalt iron boron (PtMn / CoFe / Ru / CoFeB / MgO / CoFeB), nickel iron / cobalt iron boron / magnesium oxide / cobalt iron boron (NiFe / CoFeB / MgO / CoFeB), cobalt iron boron / magnesium oxide / cobalt iron boron / magnesium oxide / cobalt iron boron (CoFeB / MgO / CoFeB / MgO / CoFeB), cobalt iron boron / magnesium oxide / cobalt iron boron / ruthenium / cobalt iron boron (CoFeB / MgO / CoFeB / Ru / CoFeB), etc.

[0090] The lower surface of the first electrode layer may be in contact with the upper surface of the first passivation layer, and the first electrode layer may serve as the bottom electrode. The lower surface of the magnetic thin film layer is in contact with the upper surface of the first electrode layer, and the magnetic thin film layer is sensitive to magnetic change signals. The lower surface of the second electrode layer may be in contact with the upper surface of the magnetic thin film layer, and the second electrode layer may serve as the top electrode. The first electrode layer and the second electrode layer may output the magnetic change signals collected by the magnetic thin film layer.

[0091] In step S130, the magnetic thin film layer group is etched to obtain a target magnetic thin film layer group with a first preset shape, so as to obtain a magnetic sensor.

[0092] According to the exemplary embodiment, the target magnetic thin film layer group with the first preset shape may include a second electrode layer having a first rectangle, a magnetic sensitive layer of the first rectangle, and a first electrode layer of the second rectangle.

[0093] In step S130, the second electrode layer and the magnetic sensitive layer may be etched based on dry etching, and the second electrode layer and the magnetic sensitive layer are etched into the first rectangle, the width of the first rectangle is 2um - 3um, and the length is 20um - 30um. Then, based on dry etching, the first electrode layer is etched, and the first electrode layer is etched into the second rectangle, the width of the second rectangle is 30um - 40um, and the length is 30um - 40um.

[0094] In step S200, the micro - motion structure of the electromagnetic MEMS actuator is prepared.

[0095] Step S200 may specifically be: etching the first passivation layer and the substrate at a second position of the substrate to obtain a micro - motion structure with a second preset shape.

[0096] According to the exemplary embodiment, the first position is on one side of the second position. The first position and the second position may be preset on the mask plate. The micro - motion structure with the second preset shape may include a rectangular micro - motion platform and a motion coupling part. The motion coupling part may be a rectangular frame. The motion coupling part may include a first elastic member, a first coupling member, a second elastic member, and a second coupling member.

[0097] The structure of the micro - motion structure has been described in the above - mentioned displacement control system 1000, so it will not be elaborated here.

[0098] For example, in step S200, the first passivation layer and the substrate of the wafer may be etched based on photolithography to obtain a micro - motion structure with a second preset shape. Then, the wafer is soaked and cleaned successively with acetone solution and ethanol to remove the residual glue on the front side. After that, the cleaned wafer is dried by the critical - point drying method of ethanol solution.

[0099] In step S300, a permanent magnet is connected to the micro motion structure to obtain an electromagnetic MEMS actuator integrated with a magnetic sensor.

[0100] According to an exemplary embodiment, in step S300, nano glue can be used to bond the permanent magnet to the upper surface of the micro motion platform of the micro motion structure.

[0101] Through the above embodiments, the present application can prepare a first passivation layer on a substrate, set a magnetic thin film layer group at a first position of the first passivation layer, and perform an etching process on the magnetic thin film layer group to obtain a target magnetic thin film layer group with a first preset shape, so as to obtain a magnetic sensor. The present application can perform an etching process on the substrate and the first passivation layer at a second position of the substrate to obtain a micro motion structure with a second preset shape. The present application can obtain an electromagnetic MEMS actuator integrated with a magnetic sensor by connecting a permanent magnet and the electromagnetic MEMS actuator.

[0102] The preparation method provided by the present application can make the electromagnetic MEMS actuator and the magnetic sensor compatible in the process, can be prepared on the same substrate without further assembly, avoiding the errors caused by manual operation, and also avoiding the interference of the assembly error to the electromagnetic MEMS actuator, realizing the miniaturization and integration of the electromagnetic MEMS actuator and the magnetic sensor.

[0103] Optionally, referring to Figure 8 , after step S130, step S100 may further include steps S140 - S160.

[0104] In step S140, a second passivation layer is prepared on the substrate.

[0105] According to an exemplary embodiment, the second passivation layer can isolate and protect the sidewalls of the magnetic thin film layer group. The second passivation layer can be SiO2.

[0106] For example, in step S140, based on a plasma enhanced chemical vapor deposition (PECVD) device, a SiO2 passivation layer can be deposited on the first passivation layer. The thickness of the second passivation layer can cover the sidewalls and the upper surface of the magnetic thin film layer group (the first electrode layer, the magnetic thin film layer, and the second electrode layer).

[0107] In step S150, an etching process is performed on the second passivation layer to obtain a first window for the first electrode layer and a second window for the second electrode layer.

[0108] According to an exemplary embodiment, after the second passivation layer covers the magnetic thin film layer group, a window opening process needs to be performed on the magnetic thin film layer group so that the first electrode layer and the second electrode layer can be exposed.

[0109] For example, in step S150, an etching process is performed on the second passivation layer (SiO2 passivation layer) to obtain a first window of the first electrode layer and a second window of the second electrode layer.

[0110] In step S160, a lead layer is disposed on the first window to obtain a first metal lead layer of the first electrode layer, and a lead layer is disposed on the second window to obtain a second metal lead layer of the second electrode, so as to obtain a magnetic sensor having a second passivation layer.

[0111] According to the exemplary embodiment, the metal lead layer can transmit the signals output by the first electrode layer and the second electrode layer outward.

[0112] For example, in step S160, a high-conductivity metal lead layer can be sputtered on the first window and the second window based on the sputtering method to obtain a first metal lead layer of the first electrode layer and a second metal lead layer of the second electrode. After that, the photoresist is removed, thereby obtaining a magnetic sensor having a second passivation layer.

[0113] Step S200 can also be specifically: etching the second passivation layer and the substrate at a second position to obtain a micromotion structure having a second preset shape.

[0114] For example, in step S200, an etching process can be performed on the second passivation layer, the first passivation layer, and the substrate of the wafer based on photolithography to obtain a micromotion structure having a second preset shape. Then, the wafer is soaked and cleaned in acetone solution and ethanol in sequence to remove the residual glue on the front side. After that, the cleaned wafer is dried by the critical point drying method of ethanol solution.

[0115] Optionally, referring to Figure 9 , after step S160, step S100 can further include step S170.

[0116] In step S170, an annealing magnetic field of a preset magnetic field and an annealing temperature of a preset temperature are applied to the magnetic sensor to obtain a magnetic thin film layer with magnetic domains in a preset direction.

[0117] According to the exemplary embodiment, the preset direction can be the preset arrangement direction of the magnetic domains of the magnetic thin film layer.

[0118] The preset magnetic field can be a magnetic field that enables the magnetic domains of the magnetic thin film layer to be in a preset direction. The magnetic field value of the preset magnetic field can be greater than the magnetic field value of the magnetic domains of the magnetic thin film layer. For example, the range of the magnetic field value of the preset magnetic field can be 1 to 1.2 T.

[0119] The preset temperature can be a temperature that enables the magnetic domains of the magnetic thin film layer to be in a preset direction. The temperature value of the preset temperature can be greater than the Curie temperature value of the magnetic thin film layer. For example, the range of the temperature value of the preset temperature can be 400 °C to 450 °C.

[0120] For example, in step S170, a preset magnetic field of 1 to 1.2 T and a preset temperature of 400°C to 450°C can be applied to the magnetic sensor to perform annealing treatment on the magnetic sensor, so that the magnetic domains of the magnetic thin film layer are oriented, enabling the tunneling magnetoresistance effect of the magnetic sensor, thereby improving the sensitivity of the magnetic sensor to magnetic change signals.

[0121] Optionally, step S130 can be specifically: etching the magnetic thin film layer group to obtain at least two magnetic thin film layer groups with a first preset shape, so as to obtain at least two magnetic sensors.

[0122] According to the exemplary embodiment, the number of magnetic sensors can be at least two. In step S130, based on dry etching, at at least two first positions, the second electrode layer and the magnetic sensitive layer are etched, and the second electrode layer and the magnetic sensitive layer are etched into at least two rectangles, each rectangle having a width of 2 μm to 3 μm and a length of 20 μm to 30 μm. Then, based on dry etching, the first electrode layer is etched, and the first electrode layer is etched into at least two rectangles, each rectangle having a width of 30 μm to 40 μm and a length of 30 μm to 40 μm, so as to obtain at least two magnetic sensors.

[0123] Optionally, in step S100, multiple magnetic sensors can be fabricated on the substrate of a wafer. In step S200, a micro-motion structure can be fabricated on the substrate of a wafer.

[0124] According to an aspect of the present application, the present application further provides an assembly method for an electromagnetic MEMS actuator integrated with a magnetic sensor and a coil driving module. The coil driving module can provide a magnetic field for driving the electromagnetic MEMS actuator.

[0125] The assembly method includes: using a silicon-based wafer for fabrication, applying nano-adhesives equal in size to the silicon-based wafer on both surfaces of the silicon-based wafer, and processing by laser cutting to cut through the two-layer nano-adhesive structure and the silicon-based wafer body structure to form a support portion. Then, the nano-adhesive film on the joint surface of the support portion and the coil driving module is peeled off, and the support portion and the coil driving module are aligned and bonded to ensure the stability of electromagnetic signal transmission. Finally, the nano-adhesive film on the joint surface of the support portion and the electromagnetic MEMS actuator integrated with the magnetic sensor is peeled off, and the support portion and the electromagnetic MEMS actuator integrated with the magnetic sensor are aligned and bonded to achieve the precise assembly of the support portion and the structure of the electromagnetic MEMS actuator integrated with the magnetic sensor.

[0126] Finally, it should be noted that the above are only preferred embodiments of the present application and are not used to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions of the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A displacement control system for an electromagnetic MEMS actuator integrated with a magnetic sensor, characterized in that, The displacement control system includes: A coil driving module; The electromagnetic MEMS actuator includes: A permanent magnet that moves under the drive of the coil driving module; A micro-motion structure fixedly connected to the permanent magnet; At least one magnetic sensor, which is disposed on the same substrate surface as the micro-motion structure and on one side of the micro-motion structure, and collects the magnetic displacement signal generated when the permanent magnet moves, so as to generate an electrical signal according to the magnetic displacement signal; A signal processing unit, which receives the electrical signal, generates a control signal according to the electrical signal, and transmits the control signal to the coil driving module, so that the coil driving module controls the movement of the permanent magnet according to the control signal to control the displacement of the micro-motion structure.

2. The displacement control system according to claim 1, characterized in that, The displacement control system further includes: A support portion, one end of which is fixedly connected to the coil driving module and the other end is fixedly connected to the micro-motion structure to support the micro-motion structure.

3. The displacement control system according to claim 2, characterized in that, The micro-motion structure includes: A micro-motion platform fixedly connected to the permanent magnet; A motion coupling portion, one end of which is elastically connected to the micro-motion platform; When the coil driving module receives the control signal, the coil driving module generates a driving magnetic field according to the control signal; The permanent magnet moves under the action of the driving magnetic field, so that the magnetic sensor collects the magnetic displacement signal generated by the movement of the permanent magnet; When the permanent magnet moves, the permanent magnet drives the movement of the micro-motion platform.

4. The displacement control system according to claim 1, characterized in that, The signal processing unit includes: A signal processor that generates position data according to the electrical signal; A position controller that generates the control signal according to the position data.

5. The displacement control system according to claim 1, characterized in that, The displacement control system includes at least two magnetic sensors, and the at least two magnetic sensors are disposed on different sides of the micro-motion structure to collect magnetic displacement signals in multiple directions generated when the permanent magnet moves.

6. The displacement control system according to claim 3, characterized in that, The motion coupling portion includes: A first elastic member, one end of which is connected to the micro-motion platform; A first coupling member, one end of which is connected to one end of the first elastic member; A second elastic member, one end of which is connected to the other end of the first coupling member; A second coupling member, one end of which is connected to the other end of the second elastic member; The magnetic sensor is disposed on the upper surface of the second coupling member.

7. A preparation method for an electromagnetic MEMS actuator integrated with a magnetic sensor, characterized in that, The preparation method includes: Steps of preparing a magnetic sensor; Steps of preparing the micro-motion structure of the electromagnetic MEMS actuator; Connecting the permanent magnet and the micro-motion structure to obtain an electromagnetic MEMS actuator integrated with a magnetic sensor; The steps of preparing the magnetic sensor include: Preparing a first passivation layer on a substrate; Setting a magnetic thin film layer group at a first position of the first passivation layer, wherein the magnetic thin film layer group includes a first electrode layer, a magnetic thin film layer, and a second electrode layer, the magnetic thin film layer is disposed between the first electrode layer and the second electrode layer, and the first electrode layer is in contact with the first passivation layer; Etching the magnetic thin film layer group to obtain a target magnetic thin film layer group with a first preset shape to obtain the magnetic sensor; The steps of preparing the micro-motion structure of the electromagnetic MEMS actuator include: Etch the substrate and the first passivation layer at a second position of the substrate to obtain a micromotion structure having a second preset shape; Wherein, the first position is located on one side of the second position.

8. The preparation method according to claim 7, wherein, After etching the magnetic thin film layer group to obtain a target magnetic thin film layer group with a first preset shape to obtain the magnetic sensor, the step of preparing the magnetic sensor further includes: Prepare a second passivation layer on the substrate; Etch the second passivation layer to obtain a first window of the first electrode layer and a second window of the second electrode layer; Set a lead layer on the first window to obtain a first metal lead layer of the first electrode layer, and set a lead layer on the second window to obtain a second metal lead layer of the second electrode, so as to obtain a magnetic sensor with the second passivation layer; The etching process of the first passivation layer and the substrate at the second position of the substrate to obtain a micromotion structure with a second preset shape includes: Etch the second passivation layer, the first passivation layer and the substrate at the second position to obtain the micromotion structure having the second preset shape.

9. The preparation method according to claim 8, wherein, After setting a lead layer on the first window to obtain a first metal lead layer of the first electrode layer, and setting a lead layer on the second window to obtain a second metal lead layer of the second electrode to obtain a magnetic sensor with the second passivation layer, the step of preparing the magnetic sensor further includes: Apply an annealing magnetic field with a preset magnetic field and an annealing temperature with a preset temperature to the magnetic sensor to obtain a magnetic thin film layer with magnetic domains in a preset direction.

10. The preparation method according to claim 7, wherein, The etching process of the magnetic thin film layer group to obtain a target magnetic thin film layer group with a first preset shape to obtain the magnetic sensor includes: Etch the magnetic thin film layer group to obtain at least two magnetic thin film layer groups with the first preset shape to obtain at least two magnetic sensors.

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