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

Abstract

A displacement control system and preparation method of an electromagnetic MEMS actuator with an integrated magnetic sensor relate to the technical field of electromagnetic MEMS actuators. The displacement control system may include a coil drive 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-motion structure. The permanent magnet moves under the drive of the coil drive module; the micro-motion structure is fixedly connected to the permanent magnet; at least one magnetic sensor and the micro-motion structure are arranged on the same substrate surface and on one side of the micro-motion structure to collect the magnetic displacement signal generated when the permanent magnet moves, so as to generate an electrical signal based on the magnetic displacement signal; the signal processing unit generates a control signal based on the electrical signal, and transmits the control signal to the coil drive module so that the coil drive module controls the movement of the permanent magnet based on the control signal to control the displacement of the micro-motion structure. By integrating the magnetic sensor and the micro-motion structure, the displacement control system of the present application has the ability to control the displacement of the micro-motion structure in a closed loop.

Description

Technical Field

[0001] The present application relates to the technical field of electromagnetic MEMS actuators, and in particular to a displacement control system and a preparation method of an electromagnetic MEMS actuator with an integrated magnetic sensor. Background Art

[0002] Typically, the electromagnetic drive structure of an electromagnetic MEMS device consists of two parts: one is a permanent magnet located on the actuator's elastic frame, which provides the driving force for the electromagnetic MEMS actuator under the influence of an external magnetic field. The other is a coil drive module. The current flowing through the coil drive module interacts with the magnetic field generated by the permanent magnet to drive the electromagnetic MEMS actuator's elastic frame.

[0003] Among them, the position detection of the electromagnetic MEMS actuator is one of the key parts in completing 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] Current position detection methods for electromagnetic MEMS actuators include high-resolution cameras, laser displacement sensors, and eddy current sensors. However, these devices are incompatible with the micro-motion structure of electromagnetic MEMS actuators due to their size and volume. While eddy current sensors offer the potential for miniaturization and integration, they suffer from drawbacks such as high excitation frequency and high power consumption.

[0005] The contents of the background technology are merely technologies known to the public and do not necessarily represent existing technologies in this field. Summary of the Invention

[0006] The present application aims to provide a displacement control system and preparation method of an electromagnetic MEMS actuator with an integrated magnetic sensor, so as to solve the problems that devices such as the above-mentioned high-resolution cameras and laser displacement sensors are difficult to be compatible with the micro-motion structure of the electromagnetic MEMS actuator 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, a displacement control system for an electromagnetic MEMS actuator with an integrated magnetic sensor is provided. The displacement control system may include a coil drive 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-motion structure. The permanent magnet moves under the drive of the coil drive module; the micro-motion structure is fixedly connected to the permanent magnet; at least one magnetic sensor is arranged on the same substrate surface as the micro-motion structure and is arranged on one side of the micro-motion structure to collect the magnetic displacement signal generated by the movement of the permanent magnet to generate an electrical signal based on the magnetic displacement signal; the signal processing unit receives the electrical signal, generates a control signal based on the electrical signal, and transmits the control signal to the coil drive module so that the coil drive module controls the movement of the permanent magnet based on the control signal to control the displacement of the micro-motion structure.

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

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

[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; and 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, which are arranged on different sides of the micro-motion 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 component, a first coupling component, a second elastic component, and a second coupling component. One end of the first elastic component is connected to the micro-motion platform; one end of the first coupling component is connected to one end of the first elastic component; one end of the second elastic component is connected to the other end of the first coupling component; one end of the second coupling component is connected to the other end of the second elastic component; and the magnetic sensor is disposed on the upper surface of the second coupling component.

[0013] According to one aspect of the present application, a method for preparing an electromagnetic MEMS actuator with an integrated magnetic sensor is provided. The method comprises: preparing a magnetic sensor; preparing 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 with an integrated magnetic sensor. The step of preparing the magnetic sensor comprises: preparing a first passivation layer on a substrate; disposing a magnetic film layer group at a first position of the first passivation layer, wherein the magnetic film layer group comprises a first electrode layer, a magnetic film layer, and a second electrode layer, the magnetic film layer being disposed between the first electrode layer and the second electrode layer, and the first electrode layer being in contact with the first passivation layer; etching the magnetic film layer group to obtain a target magnetic film layer group of a first preset shape to obtain a magnetic sensor; and the step of preparing the micro-motion structure of the electromagnetic MEMS actuator comprises: etching the substrate and the first passivation layer at a second position of the substrate to obtain a micro-motion structure having a second preset shape; wherein the first position is located to 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 of a first preset shape to obtain a magnetic sensor, the step of preparing the magnetic sensor further includes: preparing a second passivation layer on the substrate; etching the second passivation layer to obtain a first window for the first electrode layer and a second window for the second electrode layer; providing a wiring layer on the first window to obtain a first metal wiring layer for the first electrode layer, and providing a wiring layer in the second window to obtain a second metal wiring layer for the second electrode, thereby obtaining a magnetic sensor having a second passivation layer. Etching the first passivation layer and the substrate at a second position on the substrate to obtain a micro-motion structure having 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 having the second preset shape.

[0015] According to some embodiments of the present application, 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, thereby obtaining a magnetic sensor having a second passivation layer, the step of preparing the magnetic sensor further includes: applying an annealing magnetic field of a preset magnetic field and an annealing temperature of a preset temperature to the magnetic sensor to obtain a magnetic film layer with a magnetic domain in a preset direction.

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

[0017] Through the above-described embodiments, the present application can integrate the micro-motion structure of the magnetic sensor and 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 from the magnetic displacement signal. The present application can generate a control signal from the electrical signal. The present application can control the displacement of the micro-motion structure by transmitting the control signal to the coil drive module.

[0018] By integrating a magnetic sensor with a micro-motion structure, the present application's displacement control system can achieve closed-loop control of the micro-motion structure's displacement. The magnetic thin film layer in the present application is a tunnel magnetoresistive (TMR) junction, and the magnetic displacement signal is acquired via a TMR sensor. The TMR sensor's high sensitivity improves the control accuracy of the present application's displacement control system, and the TMR sensor does not require high excitation frequencies or high power consumption.

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

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 A schematic structural diagram of a displacement control system according to an embodiment of the present application is shown;

[0022] Figure 2 A schematic top view of the structure of a coil drive module, an electromagnetic MEMS actuator, a magnetic sensor, and a support portion according to an embodiment of the present application is shown;

[0023] Figure 3 A schematic diagram showing a side view of the structure of a coil drive module, an electromagnetic MEMS actuator, a magnetic sensor, and a support portion according to an embodiment of the present application is shown;

[0024] Figure 4 FIG2 shows a structural schematic diagram of a magnetic sensor according to an embodiment of the present application;

[0025] Figure 5 Another structural schematic diagram of a displacement control system according to an embodiment of the present application is shown;

[0026] Figure 6A schematic flow chart of a preparation method 2000 according to an embodiment of the present application is shown;

[0027] Figure 7 A schematic diagram of a process of step S100 according to an embodiment of the present application is shown;

[0028] Figure 8 Another flowchart of step S100 according to an embodiment of the present application is shown;

[0029] Figure 9 Another flowchart of step S100 according to an embodiment of the present application is shown.

[0030] Description of reference numerals:

[0031] Displacement control system 1000.

[0032] Coil driving module 1100 ; electromagnetic MEMS actuator 1200 ; magnetic sensor 1300 ; signal processing unit 1400 ; support portion 1500 .

[0033] Permanent magnet 1210 ; micro-motion structure 1220 .

[0034] Micro-motion platform 1221; motion coupling portion 1222.

[0035] Signal processor 1410; position controller 1420.

[0036] PID controller 1421; signal generator 1422; PWM modulator 1423.

[0037] First elastic component 12221 ; first coupling component 12222 ; second elastic component 12223 ; second coupling component 12224 .

[0038] Magnetic thin film layer group 1310 .

[0039] A first electrode layer 1311 ; a magnetic film layer 1312 ; a second electrode layer 1313 ; a first metal wiring layer 1314 ; a second metal wiring layer 1315 ; a first passivation layer 1316 ; and a second passivation layer 1317 . DETAILED DESCRIPTION

[0040] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the drawings represent like or similar parts, and thus repetitive description thereof will be omitted.

[0041] The described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. may be employed. In these cases, well-known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0042] Furthermore, the terms "include," "comprise," and "have," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0043] The terms "first", "second" and the like in the specification, claims and drawings of this application are used to distinguish different objects rather than to describe a specific order.

[0044] The following is a clear and complete description of the technical solution of this application in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of this application.

[0045] The English terms and their full English names and corresponding Chinese meanings involved in this application are:

[0046] TMR, Tunneling Magnetoresistance Sensor, tunneling magnetoresistance sensor.

[0047] PID, Proportional-Integral-Derivative Controller, Proportional-Integral-Derivative Controller.

[0048] MEMS, Micro-Electro-Mechanical System, micro-electromechanical storage system.

[0049] PECVD, Plasma-Enhanced Chemical Vapor Deposition, plasma enhanced chemical vapor deposition.

[0050] PWM, Pulse-Width Modulation, pulse width modulation.

[0051] According to one aspect of the present application, the present application provides a displacement control system of an electromagnetic MEMS actuator integrated with a magnetic sensor. 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 .

[0052] According to example embodiments, the coil driving module 1100 may be a device that converts electrical energy into mechanical energy through electromagnetic principles.

[0053] See also Figure 2 The electromagnetic MEMS actuator 1200 includes a permanent magnet 1210 and a micro-motion structure 1220 .

[0054] According to an example embodiment, the permanent magnet 1210 can move under the drive of the coil driving module 1100. The permanent magnet 1210 can be disposed near the coil driving module 1100, which can increase 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 can be movably connected to the coil driving module 1100.

[0055] According to an example embodiment, the micro-motion structure 1220 is fixedly connected to the permanent magnet 1210. The micro-motion structure 1220 may be disposed on a substrate surface of a wafer.

[0056] For example, the wafer substrate may be a silicon substrate, and the micro-motion structure 1220 may be manufactured by a semiconductor process by etching the silicon substrate, and the etched silicon frame forms the micro-motion structure 1220 .

[0057] 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 can collect the magnetic displacement signal generated by the movement of the permanent magnet 1210 and convert the magnetic displacement signal into an electrical signal. The magnetic displacement signal can be a signal of the magnetic field change when the permanent magnet 1210 is displaced. The magnetic sensor 1300 can perform magnetoresistive conversion and amplification on the magnetic displacement signal to convert the magnetic displacement signal into an electrical signal.

[0058] For example, magnetic sensor 1300 may be a TMR sensor. A TMR sensor utilizes the quantum tunneling effect to measure magnetic fields. TMR sensors have high magnetic field sensitivity and can detect very weak magnetic field changes, converting the magnetic field change signal into an electrical signal for output.

[0059] For example, see Figure 4Magnetic sensor 1300 may include a first passivation layer 1316 and a magnetic thin film layer group 1310. Magnetic thin film layer group 1310 includes a first electrode layer 1311, a magnetic thin film layer 1312, and a second electrode layer 1313. Magnetic thin film layer 1312 is disposed between first electrode layer 1311 and second electrode layer 1313. First electrode layer 1311 is in contact with first passivation layer 1316.

[0060] The substrate may be silicon, the first passivation layer 1316 may be silicon dioxide (SiO 2 ), and the first electrode layer 1311 and the second electrode layer 1313 may be metal layers such as chromium (Cr) or ruthenium (Ru). The magnetic film layer 1312 may be a tunnel magnetoresistive junction (TMR), for example, the magnetic film layer 1312 may be a multilayer film structure of 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), or the like.

[0061] First electrode layer 1311 can serve as a bottom electrode. The lower surface of magnetic film layer 1312 contacts the upper surface of first electrode layer 1311, and magnetic film layer 1312 is sensitive to magnetic change signals. The lower surface of second electrode layer 1313 can contact the upper surface of magnetic film layer 1312, and second electrode layer 1313 can serve as a top electrode. First electrode layer 1311 and second electrode layer 1313 can output the magnetic change signals collected by magnetic film layer 1312.

[0062] See also Figure 4 Magnetic sensor 1300 may further include a first metal lead layer 1314, a second metal lead layer 1315, and a second passivation layer 1317. First metal lead layer 1314 may be in contact with first electrode layer 1311, thereby electrically connecting first metal lead layer 1314 to first electrode layer 1311. Second metal lead layer 1315 may be in contact with second electrode layer 1313, thereby electrically connecting second metal lead layer 1315 to second electrode layer 1313. First metal lead layer 1314 and second metal lead layer 1315 may output magnetic change signals collected by magnetic film layer 1312.

[0063] 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 made of SiO2. The thickness of the second passivation layer 1317 can cover the sidewalls and top 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).

[0064] According to an example embodiment, the signal processing unit 1400 receives an electrical signal and generates a control signal according to the electrical signal. The control signal may be a signal for controlling the displacement of the micro-motion structure 1220 .

[0065] For example, the signal processing unit 1400 can generate position data based on the electrical signal using a positioning algorithm, and then generate a control signal based on the position data. The control signal can be a DC current signal with a constant current value or an AC current signal with a fixed amplitude.

[0066] Exemplarily, the positioning algorithm may be a fitting positioning algorithm, a neural network magnetic field mapping positioning algorithm based on a neural network model, or the like.

[0067] 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, thereby controlling the displacement of the micro-motion structure 1220 .

[0068] For example, the signal processing unit 1400 transmits a DC current signal (or AC current signal) to each coil in the coil drive module 1100. Under the influence of the DC current signal (or AC current signal), the magnetic field of the coil drive module 1100 changes. The change in the magnetic field of the coil drive module 1100 causes the permanent magnet 1210 to displace, thereby driving the micro-motion structure 1220 to displace. The magnetic sensor 1300 can continue to collect the magnetic displacement signal generated by the movement of the permanent magnet 1210, thereby forming a closed-loop control of the displacement of the micro-motion structure 1220, allowing the micro-motion structure 1220 to move to a specified position.

[0069] Through the above-described embodiments, the present application can integrate the micro-motion structure of the magnetic sensor and 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 from the magnetic displacement signal. The present application can generate a control signal from the electrical signal. The present application can control the displacement of the micro-motion structure by transmitting the control signal to the coil drive module.

[0070] By integrating a magnetic sensor with a micro-motion structure, the present application's displacement control system can achieve closed-loop control of the micro-motion structure's displacement. The magnetic thin film layer in the present application is a tunnel magnetoresistive (TMR) junction, and the magnetic displacement signal is acquired via a TMR sensor. The TMR sensor's high sensitivity improves the control accuracy of the present application's displacement control system, and the TMR sensor does not require high excitation frequencies or high power consumption.

[0071] The present application can integrate the micro-motion structure of the magnetic sensor and the electromagnetic MEMS actuator in situ on the substrate of the same wafer. The displacement control system of the present application has a simple structure, achieves miniaturization and high integration, and is suitable for application scenarios with limited space.

[0072] Alternatively, see Figure 2 and Figure 3 The displacement control system 1000 further includes a support portion 1500. One end of the support portion 1500 is fixedly connected to the coil drive module 1100, and the other end of the support portion 1500 is fixedly connected to the micro-motion structure 1220. The support portion 1500 can support the micro-motion structure 1220, making the displacement of the micro-motion structure 1220 more stable.

[0073] Alternatively, see Figure 2 and Figure 3 The micro-motion structure 1220 includes a micro-motion platform 1221 and a motion coupling portion 1222 .

[0074] According to an exemplary embodiment, the fine motion platform 1221 is fixedly connected to the permanent magnet 1210. For example, the permanent magnet 1210 can be bonded to the lower surface of the fine motion platform 1221 by nano glue. When the permanent magnet 1210 moves, the permanent magnet 1210 drives the fine motion platform 1221 to move.

[0075] One end of the motion coupling portion 1222 is elastically connected to the fine motion platform 1221. The other end of the motion coupling portion 1222 is fixedly connected to the magnetic sensor 1300. The motion coupling portion 1222 can prevent the magnetic sensor 1300 from being displaced when the fine motion platform 1221 is driven to move.

[0076] According to an exemplary embodiment, when coil drive module 1100 receives a control signal, it generates a driving magnetic field based on the control signal. The driving magnetic field causes permanent magnet 1210 to move, causing magnetic sensor 1300 to collect a magnetic displacement signal generated by the movement of permanent magnet 1210. The movement of permanent magnet 1210 drives the movement of micro-motion platform 1221.

[0077] 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 to move by the permanent magnet, the magnetic sensor is in a stable state.

[0078] Alternatively, see Figure 5 , the signal processing unit 1400 includes a signal processor 1410 and a position controller 1420 .

[0079] According to example embodiments, the signal processor 1410 may generate position data from the electrical signal.

[0080] Exemplarily, the signal processor 1410 may be a microprocessor, which may receive the amplified and filtered electrical signal, execute a positioning algorithm, and output precise position data according to the electrical signal.

[0081] According to an example embodiment, the position controller 1420 generates a control signal according to the position data.

[0082] For example, position controller 1420 may include a PID controller 1421, a signal generator 1422, and a PWM modulator 1423. PID controller 1421 may generate a target position signal based on position data. Signal generator 1422 may generate a continuous waveform (e.g., a sine / triangle wave) of the target position signal. PWM modulator 1423 may modulate the amplitude and energy of the continuous waveform of the target position signal to convert the target position signal into a control signal. PWM modulator 1423 transmits the control signal to coil drive module 1100.

[0083] 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, thereby realizing digital control of the control signal.

[0084] Alternatively, see Figure 2 The displacement control system 1000 includes at least two magnetic sensors 1300 , which 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.

[0085] For example, see Figure 2The micro-motion structure 1220 of the electromagnetic MEMS actuator 1200 can be a rectangular structure. The displacement control system 1000 includes four magnetic sensors 1300. The four magnetic sensors 1300 can be respectively arranged around the micro-motion structure 1220. The four magnetic sensors 1300 can be divided into two groups. Two magnetic sensors 1300 can collect magnetic displacement signals in the X horizontal direction in a Cartesian coordinate system, and the other two magnetic sensors 1300 can collect magnetic displacement signals in the Y horizontal direction in a Cartesian coordinate system.

[0086] Alternatively, see Figure 2 The motion coupling portion 1222 includes a first elastic component 12221 , a first coupling component 12222 , a second elastic component 12223 and a second coupling component 12224 .

[0087] According to an exemplary embodiment, one end of the first elastic component 12221 is connected to the fine motion platform 1221. One end of the first coupling component 12222 is connected to one end of the first elastic component 12221. One end of the second elastic component 12223 is connected to the other end of the first coupling component 12222. One end of the second coupling component 12224 is connected to the other end of the second elastic component 12223.

[0088] For example, see Figure 2 The first elastic component 12221 and the second elastic component 12223 may be elastic silicon structures. The first coupling component 12222 and the second coupling component 12224 may be elastic silicon frame structures.

[0089] Magnetic sensor 1300 is disposed on the upper surface of the second coupling member. When fine-motion platform 1221 is driven to move, due to the coupling effect of first elastic component 12221, first coupling component 12222, second elastic component 12223, and second coupling component 12224, first elastic component 12221, first coupling component 12222, and second elastic component 12223 can be driven to move by fine-motion platform 1221, while second coupling component 12224 does not move, thereby maintaining a stable position for magnetic sensor 1300.

[0090] Through the above embodiment, the present application can elastically connect the first elastic component to the micro-motion platform, with one end of the first coupling component connected to one end of the first elastic component. One end of the second elastic component is connected to the other end of the first coupling component. One end of the second coupling component is connected to the other end of the second elastic component, so that when the micro-motion platform is driven to move by the permanent magnet, the magnetic sensor is in a stable state.

[0091] According to one aspect of the present application, the present application provides a method 2000 for preparing an electromagnetic MEMS actuator with an integrated magnetic sensor, see Figure 6, the preparation method 2000 includes steps S100-S300.

[0092] In step S100 , a magnetic sensor is prepared.

[0093] See also Figure 7 , step S100 may include steps S110 to S130.

[0094] In step S110 , a first passivation layer is prepared on the substrate.

[0095] According to example embodiments, the wafer may be a silicon (Si)-based wafer, the substrate may be silicon, and the first passivation layer may be silicon dioxide (SiO 2 ).

[0096] For example, in step S110, acetone, anhydrous ethanol, and deionized water are used to clean the silicon-based wafer in sequence.

[0097] 1um~2um thick SiO2.

[0098] In step S120 , a magnetic thin film layer group is disposed at a first position of the first passivation layer.

[0099] According to an example embodiment, in step S120, a magnetic thin film layer group is sputtered onto the first passivation layer using magnetron sputtering. The magnetic thin film layer group has 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.

[0100] The first electrode layer and the second electrode layer may be metal layers such as chromium (Cr) or ruthenium (Ru). The magnetic film layer may be a tunnel magnetoresistive (TMR) junction, for example, a multilayer film structure of 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), or cobalt iron boron / magnesium oxide / cobalt iron boron / ruthenium / cobalt iron boron (CoFeB / MgO / CoFeB / Ru / CoFeB).

[0101] The lower surface of the first electrode layer can contact the upper surface of the first passivation layer, and the first electrode layer can serve as a bottom electrode. The lower surface of the magnetic film layer can contact the upper surface of the first electrode layer, and the magnetic film layer is sensitive to magnetic change signals. The lower surface of the second electrode layer can contact the upper surface of the magnetic film layer, and the second electrode layer can serve as a top electrode. The first and second electrode layers can output the magnetic change signals collected by the magnetic film layer.

[0102] 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.

[0103] According to example embodiments, a target magnetic thin film layer group of a first preset shape may include a second electrode layer having a first rectangular shape, a magnetic sensitive layer having a first rectangular shape, and a first electrode layer having a second rectangular shape.

[0104] In step S130, the second electrode layer and the magnetically sensitive layer can be etched by dry etching to form a first rectangle having a width of 2 μm to 3 μm and a length of 20 μm to 30 μm. The first electrode layer can then be etched by dry etching to form a second rectangle having a width of 30 μm to 40 μm and a length of 30 μm to 40 μm.

[0105] In step S200, a micro-motion structure of an electromagnetic MEMS actuator is prepared.

[0106] Step S200 may specifically include: etching the first passivation layer and the substrate at a second position of the substrate to obtain a micro-motion structure having a second preset shape.

[0107] According to an example embodiment, the first position is located to one side of the second position. The first position and the second position can be pre-set on the mask. The micro-motion structure of the second preset shape can include a rectangular micro-motion platform and a motion coupling portion. The motion coupling portion can be a rectangular frame. The motion coupling portion can include a first elastic component, a first coupling component, a second elastic component, and a second coupling component.

[0108] The structure of the micro-motion structure has been described in the above-mentioned displacement control system 1000 and will not be repeated here.

[0109] For example, in step S200, the first passivation layer and the wafer substrate can be etched using a photolithography process to obtain a micro-motion structure having a second predetermined shape. The wafer is then cleaned by sequentially soaking in acetone and ethanol to remove residual adhesive from the front surface. The cleaned wafer is then dried using critical point drying with an ethanol solution.

[0110] In step S300 , the permanent magnet and the micro-motion structure are connected to obtain an electromagnetic MEMS actuator with an integrated magnetic sensor.

[0111] According to an example embodiment, in step S300 , nano glue may be used to bond the permanent magnet to the upper surface of the micro-motion platform of the micro-motion structure.

[0112] Through the above-described embodiments, the present application can prepare a first passivation layer on a substrate, dispose a magnetic thin film layer group at a first position on the first passivation layer, and etch the magnetic thin film layer group to obtain a target magnetic thin film layer group of a first preset shape to obtain a magnetic sensor. The present application can etch the substrate and the first passivation layer at a second position on the substrate to obtain a micro-motion structure having a second preset shape. The present application can connect a permanent magnet and the electromagnetic MEMS actuator to obtain an electromagnetic MEMS actuator with an integrated magnetic sensor.

[0113] The preparation method provided in this application can make electromagnetic MEMS actuators and magnetic sensors compatible in terms of process, and can be prepared on the same substrate without further assembly, thus avoiding errors caused by human labor. At the same time, it also avoids the interference of assembly errors on the electromagnetic MEMS actuator, thereby realizing the miniaturization and integration of electromagnetic MEMS actuators and magnetic sensors.

[0114] Alternatively, see Figure 8 After step S130, step S100 may further include steps S140 to S160.

[0115] In step S140 , a second passivation layer is prepared on the substrate.

[0116] According to example embodiments, the second passivation layer may isolate and protect sidewalls of the magnetic thin film layer group. The second passivation layer may be SiO2.

[0117] For example, in step S140, a SiO2 passivation layer may be deposited on the first passivation layer using plasma-enhanced chemical vapor deposition (PECVD) equipment. The second passivation layer may have a thickness sufficient to cover the sidewalls and top surface of the magnetic thin film layer group (the first electrode layer, the magnetic thin film layer, and the second electrode layer).

[0118] In step S150 , the second passivation layer is etched to obtain a first window of the first electrode layer and a second window of the second electrode layer.

[0119] According to example embodiments, after the second passivation layer covers the magnetic thin film layer group, a windowing 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.

[0120] For example, in step S150 , the second passivation layer (SiO 2 passivation layer) is etched to obtain a first window of the first electrode layer and a second window of the second electrode layer.

[0121] In step S160 , a wiring layer is provided on the first window to obtain a first metal wiring layer of the first electrode layer, and a wiring layer is provided on the second window to obtain a second metal wiring layer of the second electrode to obtain a magnetic sensor with a second passivation layer.

[0122] According to example embodiments, the metal wiring layer may transmit signals output by the first electrode layer and the second electrode layer to the outside.

[0123] For example, in step S160, a high-conductivity metal lead layer can be sputtered on the first window and the second window based on a sputtering method to obtain a first metal lead layer of the first electrode layer and a second metal lead layer of the second electrode. Thereafter, the photoresist is removed to obtain a magnetic sensor with a second passivation layer.

[0124] Step S200 may also be specifically: etching the second passivation layer and the substrate at the second position to obtain a micro-motion structure having a second preset shape.

[0125] For example, in step S200, the second passivation layer, the first passivation layer, and the wafer substrate can be etched using a photolithography process to obtain a micro-motion structure having a second predetermined shape. The wafer is then cleaned by sequentially soaking in acetone and ethanol to remove residual adhesive from the front surface. The cleaned wafer is then dried using critical point drying with an ethanol solution.

[0126] Alternatively, see Figure 9 , after step S160, step S100 may further include step S170.

[0127] 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.

[0128] According to example embodiments, the preset direction may be a preset arrangement direction of magnetic domains of the magnetic thin film layer.

[0129] The preset magnetic field can be a magnetic field that causes the magnetic domains of the magnetic 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 film layer. For example, the magnetic field value of the preset magnetic field can range from 1 to 1.2 T.

[0130] The preset temperature may be a temperature at which the magnetic domains of the magnetic film layer are aligned in a preset direction. The preset temperature may be a temperature greater than the Curie temperature of the magnetic film layer. For example, the preset temperature may be in a range of 400° C. to 450° C.

[0131] 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. may be applied to the magnetic sensor to perform annealing treatment, so that the magnetic domains of the magnetic thin film layer are oriented and arranged, so that the magnetic sensor has a tunnel magnetoresistance effect, thereby improving the sensitivity of the magnetic sensor to magnetic change signals.

[0132] Optionally, step S130 may specifically include: performing an etching process on the magnetic thin film layer group to obtain at least two magnetic thin film layer groups of a first preset shape, so as to obtain at least two magnetic sensors.

[0133] According to example embodiments, the number of magnetic sensors may be at least two. In step S130, the second electrode layer and the magnetically sensitive layer may be etched at at least two first locations using dry etching to form at least two rectangles, each with a width of 2 μm to 3 μm and a length of 20 μm to 30 μm. The first electrode layer may then be etched using dry etching to form at least two rectangles, each with a width of 30 μm to 40 μm and a length of 30 μm to 40 μm, thereby forming at least two magnetic sensors.

[0134] Optionally, in step S100, a plurality of magnetic sensors may be fabricated on a substrate of a wafer. In step S200, a micro-motion structure may be fabricated on a substrate of a wafer.

[0135] According to one aspect of the present application, the present application also provides a method for assembling an electromagnetic MEMS actuator with an integrated magnetic sensor and a coil drive module. The coil drive module can provide a magnetic field for driving the electromagnetic MEMS actuator.

[0136] The assembly method includes: using a silicon-based wafer, applying nano-glue of equal size to both surfaces of the silicon-based wafer, and then using a laser cutting method to cut through the two layers of nano-glue structure and the silicon-based wafer body structure to form a support portion. Next, the nano-glue coating on the interface between the support portion and the coil drive module is removed, and the support portion and the coil drive module are aligned and bonded to ensure the stability of electromagnetic signal transmission. Finally, the nano-glue coating on the interface between the support portion and the electromagnetic MEMS actuator with an integrated magnetic sensor is removed, and the support portion and the electromagnetic MEMS actuator with an integrated magnetic sensor are aligned and bonded to ensure the precise assembly of the support portion and the electromagnetic MEMS actuator with an integrated magnetic sensor structure.

[0137] Finally, it should be noted that the above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Although the present application is described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions of the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing an electromagnetic MEMS actuator with an integrated magnetic sensor, characterized in that: The preparation method comprises: Steps for preparing a magnetic sensor; Steps for preparing the micro-motion structure of electromagnetic MEMS actuator; connecting a permanent magnet and the micro-motion structure to obtain an electromagnetic MEMS actuator with an integrated magnetic sensor; The steps of preparing the magnetic sensor include: preparing a first passivation layer on the 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; performing an etching process on the magnetic thin film layer group to obtain a target magnetic thin film layer group of a first preset shape, so as to obtain the magnetic sensor; The steps of preparing the micro-motion structure of the electromagnetic MEMS actuator include: Etching the substrate and the first passivation layer at a second position of the substrate to obtain a micro-motion structure having a second preset shape; The first position is located on one side of the second position.

2. The preparation method according to claim 1, characterized in that After etching the magnetic thin film layer group to obtain a target magnetic thin film layer group of a first preset shape to obtain the magnetic sensor, the step of preparing the magnetic sensor further includes: preparing a second passivation layer on the substrate; performing an etching process on the second passivation layer to obtain a first window of the first electrode layer and a second window of the second electrode layer; Arranging a wiring layer on the first window to obtain a first metal wiring layer of the first electrode layer, and arranging a wiring layer on the second window to obtain a second metal wiring layer of the second electrode, thereby obtaining a magnetic sensor having 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 micro-motion structure having a second preset shape includes: The second passivation layer, the first passivation layer and the substrate are etched at the second position to obtain the micro-motion structure having the second preset shape.

3. The preparation method according to claim 2, characterized in that After providing a wiring layer on the first window to obtain a first metal wiring layer of the first electrode layer, and providing a wiring layer on the second window to obtain a second metal wiring layer of the second electrode, thereby obtaining a magnetic sensor having the second passivation layer, the step of preparing the magnetic sensor further includes: 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 film layer with magnetic domains in a preset direction.

4. The preparation method according to claim 1, characterized in that The etching process is performed on the magnetic thin film layer group to obtain a target magnetic thin film layer group of a first preset shape to obtain the magnetic sensor, comprising: The magnetic thin film layer group is etched to obtain at least two magnetic thin film layer groups of the first preset shape, thereby obtaining at least two magnetic sensors.

5. A displacement control system, characterized in that: An electromagnetic MEMS actuator with an integrated magnetic sensor, a coil drive module, and a signal processing unit prepared by the preparation method according to any one of claims 1 to 4; Wherein, the permanent magnet of the electromagnetic MEMS actuator of the integrated magnetic sensor moves under the drive of the coil drive module; The magnetic sensor collects a 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-motion structure.

6. The displacement control system according to claim 5, characterized in that: The displacement control system further comprises: The support portion has one end fixedly connected to the coil drive module and the other end fixedly connected to the micro-motion structure to support the micro-motion structure.

7. The displacement control system according to claim 6, characterized in that: The micro-motion structure comprises: 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 micro-motion platform to move.

8. The displacement control system according to claim 5, characterized in that: The signal processing unit includes: a signal processor, configured to generate position data based on the electrical signal; A position controller generates the control signal according to the position data.

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

10. The displacement control system according to claim 7, characterized in that: The motion coupling portion comprises: a first elastic component, one end of which is connected to the micro-motion platform; a first coupling component, one end of which is connected to one end of the first elastic component; a second elastic component, one end of which is connected to the other end of the first coupling component; a second coupling component, one end of which is connected to the other end of the second elastic component; The magnetic sensor is arranged on the upper surface of the second coupling member.

Images