MEMS actuator and preparation method and application thereof

Abstract

The invention provides an MEMS actuator and a preparation method and application thereof. The actuator comprises a connecting structure which comprises a first connecting block, a second connecting block, a third connecting block and a connecting frame; a micro-motion platform; the pair of first folding beams is connected with the micro-motion platform through a first connecting block and connected with the connecting frame through a second connecting block; the pair of first out-of-plane motion suppression structures is connected with each first folding beam to form a first closed structure; the micro-motion platform is surrounded by the first closed structure, and the first closed structure is surrounded by the connecting frame; the pair of second folding beams are connected with the connecting frame through third connecting blocks respectively and are orthogonal to the arrangement direction of the pair of first folding beams; the pair of second out-of-plane motion suppression structures are respectively connected with each second folding beam to form a second closed structure; the frame structure is surrounded by the second closed structure; the driving structure is connected with the frame structure; and the integrated lens structure is rigidly connected with the micro-motion platform. The MEMS actuator provided by the invention is excellent in performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-electro-mechanical system (MEMS), and in particular to a MEMS actuator and a preparation method and application thereof. BACKGROUND

[0002] MEMS actuators, especially large-stroke MEMS actuators, are increasingly attracting attention in various fields. These actuators are essential in precision engineering and nanoscale manipulation, enabling large-range movement while controlling minute motion. However, the movement process of elastic frame type MEMS actuators needs to comply with Hooke's law, where the restoring force is equal to the driving force, and the size of the restoring force complies with Hooke's law, i.e., the size of the restoring force is directly proportional to the product of the stroke and the stiffness of the supporting beam. Within the elastic deformation range, the driving force applied by the device must be equal to the inherent restoring force of the device. Therefore, the size of the driving force applied by the device is closely related to the bending stiffness of the device and its displacement range.

[0003] The size of the driving force is an important parameter of the MEMS actuator. This parameter is usually related to the characteristics of the driving voltage, the driving current, or the strength of the bias magnetic field related to the actuator, and increasing the driving force is essentially closely related to power consumption, size, economic considerations, and other "cost-related" parameters. Therefore, there are inherent limitations that cannot unconditionally increase the driving force. This means that as the stroke increases, the stiffness of the supporting beam must be reduced. An example of this trade-off is the widespread use of folded beams in large-stroke micro actuators.

[0004] The stiffness is defined by the geometric and material parameters of the device, and a low-stiffness cantilever beam will lead to harmful motion, especially an increase in motion along the Z-axis. Therefore, the trade-off between the stroke range and the stiffness is a major obstacle in developing MEMS actuators that can achieve large pure in-plane displacement while maintaining structural integrity and precision.

[0005] The contents of the background art section merely represent the technology known to the inventors, and do not necessarily represent the state of the art in the field. SUMMARY

[0006] To solve at least one of the above technical problems, the first aspect of the present application provides a MEMS actuator, comprising:

[0007] The frame structure comprises:

[0008] The connecting structure comprises a first connecting block, a second connecting block, a third connecting block, and a connecting frame.

[0009] The micro-motion platform comprises:

[0010] a pair of first folding beams, respectively connected to the micro-motion platform through the first connecting blocks and connected to the connecting frame through the second connecting blocks;

[0011] a pair of first out-of-plane motion suppression structures, respectively connected to each of the first folding beams to form a first closed structure, wherein the micro-motion platform is surrounded by the first closed structure, and the first closed structure is surrounded by the connecting frame;

[0012] a pair of second folding beams, respectively connected to the connecting frame through the third connecting blocks, and the pair of second folding beams are orthogonal to the arrangement direction of the pair of first folding beams; and

[0013] a pair of second out-of-plane motion suppression structures, respectively connected to each of the second folding beams to form a second closed structure, wherein the frame structure is surrounded by the second closed structure;

[0014] a driving structure connected to the frame structure for providing power to the frame structure, and an integrated lens structure rigidly connected to the micro-motion platform;

[0015] The first connecting points at which the pair of first out-of-plane motion suppression structures are connected to the pair of first folding beams satisfy that, when the pair of first out-of-plane motion suppression structures are not present, if the pair of first folding beams are subjected to a force parallel to a first plane of the first closed structure, common-mode motion can occur at the first connecting points, and if subjected to a force in a direction perpendicular to the first plane, differential-mode motion can occur at the first connecting points.

[0016] The second connecting points at which the pair of second out-of-plane motion suppression structures are connected to the pair of second folding beams satisfy that, when the pair of second out-of-plane motion suppression structures are not present, if the pair of second folding beams are subjected to a force parallel to a second plane of the second closed structure, common-mode motion can occur at the second connecting points, and if subjected to a force in a direction perpendicular to the second plane, differential-mode motion can occur at the second connecting points.

[0017] In some embodiments of the present application, the bending stiffness of the pair of first out-of-plane motion suppression structures and the pair of second out-of-plane motion suppression structures is greater than the torsional stiffness of the pair of first folding beams and the pair of second folding beams during the motion of the MEMS actuator.

[0018] In some embodiments of the present application, the first connecting points are the bending ends of each of the first folding beams, and the second connecting points are the bending ends of each of the second folding beams.

[0019] In some embodiments of the present application, the driving structure comprises a permanent magnet and a coil, the permanent magnet is bonded in the micro-motion platform, the integrated lens structure is bonded in the permanent magnet and surrounded by the permanent magnet; and the coil is located below the frame structure.

[0020] In some embodiments of the present application, the permanent magnet is annular and the polarization direction is perpendicular to the coil.

[0021] The coil comprises a first coil and a second coil, the first coil and the second coil rotate in opposite directions under the magnetic field of the permanent magnet after being energized; the first coil and the second coil have a first gap therebetween, the first gap is aligned with the integrated lens structure, thereby forming an optical path.

[0022] In some embodiments of the present application, the MEMS actuator further comprises:

[0023] a spacer located between the coil and the frame structure and bonded with the frame structure for supporting the frame structure; and

[0024] a tube structure for supporting the coil, the coil being integrated in the tube structure; a portion of the tube structure aligned with the integrated lens structure has a second gap, thereby forming the optical path.

[0025] A second aspect of the present application provides a method for preparing the MEMS actuator as described above, comprising:

[0026] preparing the frame structure, comprising:

[0027] lithographing the shape of the frame structure on a substrate; and

[0028] etching the substrate, thereby obtaining the frame structure;

[0029] connecting the driving structure with the frame structure; and

[0030] forming a rigid connection between the integrated lens structure and the micro-motion platform.

[0031] In some embodiments of the present application, lithographing the shape of the frame structure on a substrate comprises:

[0032] depositing a metal film on the back of the first substrate;

[0033] coating photoresist on the metal film, and then exposing the photoresist coated on the surface of the metal film under the condition of no mask shielding;

[0034] lithographing a shape of the frame structure on a front surface of the first substrate;

[0035] applying an adhesive on a front surface of a second substrate; and

[0036] bonding the front surface of the second substrate to a back surface of the first substrate by the adhesive.

[0037] In some embodiments of the present application, etching the substrate to obtain the frame structure comprises:

[0038] etching the front surface of the first substrate according to the shape of the frame structure until the metal film of the back surface of the first substrate is exposed;

[0039] separating the second substrate from the first substrate; and

[0040] removing the metal film of the first substrate after separation.

[0041] In some embodiments of the present application, the driving structure comprises a permanent magnet and a powered coil, a polarization direction of the permanent magnet is perpendicular to the powered coil; the powered coil comprises a first powered coil and a second powered coil, rotation directions of the first powered coil and the second powered coil under a magnetic field of the permanent magnet after being powered are opposite; the first powered coil and the second powered coil have a first gap therebetween;

[0042] connecting the driving structure to the frame structure comprises:

[0043] bonding the permanent magnet in the micro-motion platform; and

[0044] attaching the first powered coil and the second powered coil under the frame structure, and making the first gap align with the integrated lens structure;

[0045] forming a rigid connection between the integrated lens structure and the micro-motion platform comprises:

[0046] bonding the integrated lens structure in the permanent magnet and being surrounded by the permanent magnet.

[0047] In some embodiments of the present application, the MEMS actuator further comprises a spacer and a tube structure, the tube structure has a second gap, and the method further comprises:

[0048] assembling the spacer, the tube structure and the frame structure, so that the spacer is located between the powered coil and the frame structure, and is bonded to the frame structure, and so that the powered coil is integrated in the tube structure, and the second gap aligns with the integrated lens structure.

[0049] The third aspect of the present application provides an application of the MEMS actuator in a light beam steering system, an optical image stabilizer, an atomic force microscope and / or cell operation.

[0050] The frame structure of the MEMS actuator of the present application contains two pairs of folded beams and two pairs of out-of-plane motion suppression structures, by connecting the folded beams and the out-of-plane motion suppression structures, the longitudinal motion of the MEMS actuator is converted into differential motion between the folded beams, forming a differential motion suppression structure, thereby effectively enhancing the out-of-plane motion stiffness of the MEMS actuator and improving the performance of the MEMS actuator.

[0051] The preparation method provided by the present application is precise in process, and the prepared MEMS actuator has large out-of-plane motion stiffness and excellent performance.

[0052] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art according to these drawings without departing from the scope of the present application.

[0054] Figure 1 is a plan view of the MEMS actuator provided according to an embodiment of the present application.

[0055] Figure 2 is Figure 1 is a cross-sectional view of the MEMS actuator.

[0056] Figure 3 is Figure 1 is a schematic view of the arrangement of the energized coil of the MEMS actuator.

[0057] Figure 4 is a process flow chart for preparing the MEMS actuator according to an embodiment of the present application.

[0058] Figure 5 is a process flow chart for preparing the frame structure of the MEMS actuator according to an embodiment of the present application.

[0059] Figure 6 is a flowchart for preparing the frame structure of the MEMS actuator according to an embodiment of the present application. DETAILED DESCRIPTION

[0060] In the following, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are considered to be exemplary in nature rather than limiting.

[0061] The disclosure hereafter provides many different embodiments or examples for implementing different structures of the present application. For the purpose of simplification, the components of the particular examples and arrangements are described hereafter. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application can repeat reference numerals and / or reference letters in different examples and this repetition is for the purpose of simplification and clarity and is not intended to indicate that the described various embodiments and / or arrangements are related. In addition, the present application provides various specific examples of processes and materials, but one of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0062] It should be noted that unless otherwise expressly specified and limited, the terms "connected", "coupled", "connection" are to be construed broadly and can be either fixed or removable connections or integrally formed, and can be mechanical, electrical, or communicative connections, or combinations thereof, and can be direct or indirect, and can be internal to an element or external to an element, or combinations thereof. Those of ordinary skill in the art would understand the specific meaning of the above terms in the context of the present disclosure. In addition, in the drawings, the thickness, proportions, and dimensions of the components are exaggerated or reduced for the purpose of effectively describing the technical content.

[0063] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings and examples, so that the technical scheme of the present application and the advantages of each aspect can be better understood. However, the specific embodiments and examples described below are for illustrative purposes only, not as a limitation of the present application.

[0064] Figures 1 to 3 A MEMS actuator provided by an embodiment of the present application is shown, which includes a frame structure 10, a driving structure 20, and an integrated lens structure 30.

[0065] The frame structure 10 is the main structure of the actuator, which includes a micro-motion platform 11, a pair of first folded beams 12a, 12b, a pair of first out-of-plane motion suppression structures 13a, 13b, a pair of second folded beams 14a, 14b, a pair of second out-of-plane motion suppression structures 15a, 15b, and a connecting structure. The connecting structure includes a first connecting block 16a, a second connecting block 16b, a third connecting block 16c, a fourth connecting block 16e, and a connecting frame 16d.

[0066] The micro-motion platform 11 is a mechanical interface for the actuator to provide displacement to the outside world.

[0067] The pair of first folded beams 12a, 12b includes a first-1 folded beam 12a and a first-2 folded beam 12b. The first-1 folded beam 12a and the first-2 folded beam 12b are connected to the micro-motion platform 11 through a first connecting block 16a and connected to the connecting frame 16d through a second connecting block 16b, respectively. As shown in the figure, the micro-motion platform 11 is connected to the middle part of the first-1 folded beam 12a and the first-2 folded beam 12b, respectively. Figure 1

[0068] The pair of first out-of-plane motion suppression structures 13a, 13b includes a first-1 out-of-plane motion suppression structure 13a and a first-2 out-of-plane motion suppression structure 13b. The first-1 out-of-plane motion suppression structure 13a and the first-2 out-of-plane motion suppression structure 13b are connected to the first-1 folded beam 12a and the first-2 folded beam 12b, respectively, thereby forming a first closed structure.

[0069] In this application, the four first connecting points L1, at which the first-1 out-of-plane motion suppression structure 13a and the first-2 out-of-plane motion suppression structure 13b are connected to the first-1 folded beam 12a and the first-2 folded beam 12b, all satisfy the following conditions: when the first-1 out-of-plane motion suppression structure 13a and the first-2 out-of-plane motion suppression structure 13b are not present, the first-1 folded beam 12a and the first-2 folded beam 12b are subjected to a force parallel to the first plane (i.e. the paper plane in this embodiment) of the first closed structure, can have a common-mode motion at the first connecting point L1, i.e. there is almost no differential-mode component, and can have a differential-mode motion at the first connecting point L1 if subjected to a force in a direction perpendicular to the first plane (i.e. the out-of-plane direction). In other words, the first connecting point L1 is a position at which the first-1 folded beam 12a and the first-2 folded beam 12b can have a common-mode motion when subjected to a force parallel to the first plane and can have a differential-mode motion when subjected to a force in a direction perpendicular to the first plane, in the absence of the first-1 out-of-plane motion suppression structure 13a and the first-2 out-of-plane motion suppression structure 13b. The common-mode motion refers to the motion in the same direction and with the same amplitude, and the differential-mode motion refers to the motion opposite to the common-mode motion, i.e. in the opposite direction and with the same amplitude.

[0070] In this embodiment, the first connecting point L1 is the bent end of the first-1 folded beam 12a and the first-2 folded beam 12b. In this application, the "bent end" refers to the bending position of the folded beam. As shown in the figure, Figure 1 ​As shown, the two bent ends of the first-1 folding beam 12a are connected with the first-1 out-of-plane motion suppression structure 13a and the first-2 out-of-plane motion suppression structure 13b respectively, and the two bent ends of the first-2 folding beam 12b are connected with the first-1 out-of-plane motion suppression structure 13a and the first-2 out-of-plane motion suppression structure 13b respectively, thereby forming a first closed structure. The micro-motion platform 11 is surrounded by the first closed structure (i.e. the micro-motion platform 11 is located in the first closed structure), and the first closed structure is surrounded by the connecting frame 16d (i.e. the first closed structure is located in the connecting frame 16d).

[0071] A pair of second folding beams 14a, 14b includes a second-1 folding beam 14a and a second-2 folding beam 14b. The second-1 folding beam 14a and the second-2 folding beam 14b are connected with the connecting frame 16d through a third connecting block 16c respectively. Among them, the arrangement direction of the second-1 folding beam 14a and the second-2 folding beam 14b is orthogonal to the arrangement direction of the first-1 folding beam 12a and the first-2 folding beam 12b. As can be seen from Figure 1 As can be seen from the figure, the arrangement direction of the first-1 folding beam 12a and the first-2 folding beam 12b is the up-down direction, and the arrangement direction of the second-1 folding beam 14a and the second-2 folding beam 14b is the left-right direction.

[0072] A pair of second out-of-plane motion suppression structures 15a, 15b includes a second-1 out-of-plane motion suppression structure 15a and a second-2 out-of-plane motion suppression structure 15b. The second-1 out-of-plane motion suppression structure 15a and the second-2 out-of-plane motion suppression structure 15b are connected with the second-1 folding beam 14a and the second-2 folding beam 14b respectively, thereby forming a second closed structure. The frame structure 16d is surrounded by the second closed structure (i.e. the connecting frame 16d is located in the second closed structure).

[0073] Similar to the four second connection points L2 connecting the 1-1st off-plane motion suppression structure 13a and the 1-2nd off-plane motion suppression structure 13b with the 1-1st folding beam 12a and the 1-2nd folding beam 12b, and the 2-1st off-plane motion suppression structure 15a and the 2-2nd off-plane motion suppression structure 15b with the 2-1st folding beam 14a and the 2-2nd folding beam 14b, the following conditions are met: when the 2-1st off-plane motion suppression structure 15a and the 2-2nd off-plane motion suppression structure 15b do not exist, the 2-1st folding beam 14a and the 2-2nd folding beam 14b are subjected to a force parallel to the second plane of the second closed structure (i.e., the paper surface in this embodiment), and can undergo common-mode motion at the second connection point L2, that is, there is almost no differential-mode component, and if subjected to a force in a direction perpendicular to the first plane (i.e., the off-plane direction), differential-mode motion can occur at the second connection point L2. In other words, the second connection point L2 is a position where the 2-1st folding beam 14a and the 2-2nd folding beam 14b themselves can undergo common-mode motion when subjected to a force parallel to the first plane, and can undergo differential-mode motion if subjected to a force perpendicular to the first plane, when there is no 2-1st out-of-plane motion suppression structure 15a and the 2-2nd out-of-plane motion suppression structure 15b.

[0074] In this embodiment, the second connection point L2 is the bent end of the 2-1st folding beam 14a and the 2-2nd folding beam 14b. Figure 1 As shown, the two bent ends of the 2-1st folding beam 14a are respectively connected to the 2-1st out-of-plane motion suppression structure 15a and the 2-2nd out-of-plane motion suppression structure 15b, and the two bent ends of the 2-2nd folding beam 14b are respectively connected to the 2-1st out-of-plane motion suppression structure 15a and the 2-2nd out-of-plane motion suppression structure 15b, thereby forming a second closed structure.

[0075] In the present application, the 1-1 folding beam 12a and the 1-2 folding beam 12b provide horizontal direction elasticity, the 1-1 out-of-plane motion suppression structure 13a and the 1-2 out-of-plane motion suppression structure 13b are used to increase the out-of-plane stiffness of the 1-1 folding beam 12a and the 1-2 folding beam 12b; the 2-1 folding beam 14a and the 2-2 folding beam 14b provide horizontal direction elasticity, the 2-1 out-of-plane motion suppression structure 15a and the 2-2 out-of-plane motion suppression structure 15b are used to increase the out-of-plane stiffness of the 2-1 folding beam 14a and the 2-2 folding beam 14b; the connecting frame 16d connects the 1-1 folding beam 12a, the 1-2 folding beam 12b, the 2-1 folding beam 14a and the 2-2 folding beam 14b into one body through the second connecting block 16b and the third connecting block 16c. The micro-motion platform 11 is connected with the 1-1 folding beam 12a and the 1-2 folding beam 12b through the first connecting block 16a, and provides two degrees of freedom of displacement in the length direction and the width direction parallel to the paper plane under the common constraint of the 1-1 folding beam 12a, the 1-2 folding beam 12b, the 2-1 folding beam 14a and the 2-2 folding beam 14b.

[0076] The frame structure of the MEMS actuator of the present application contains two pairs of folding beams and two pairs of out-of-plane motion suppression structures, the longitudinal motion of the MEMS actuator is converted into differential motion between the folding beams by connecting the folding beams and the out-of-plane motion suppression structures, a differential motion suppression structure (out-of-plane motion suppression structure) is formed, thereby effectively enhancing the out-of-plane motion stiffness of the MEMS actuator and improving the performance of the MEMS actuator.

[0077] The out-of-plane motion suppression structure provided by the present application can significantly enhance the out-of-plane (longitudinal) stiffness of the system without increasing the in-plane (horizontal direction) stiffness. When moving in the plane, the out-of-plane motion suppression structure remains in a force-free state, so it does not increase the stiffness in this direction. When moving out of the plane, the out-of-plane motion suppression structure exhibits force characteristics similar to a bending beam structure, and this structure design has a specific rotation angle at both ends, so that it can effectively increase the out-of-plane stiffness of the system.

[0078] In some embodiments of the present application, the bending stiffness of a pair of first out-of-plane motion suppression structures 13a, 13b and a pair of second out-of-plane motion suppression structures 15a, 15b is greater than the torsional stiffness of a pair of first folding beams 12a, 12b and a pair of second folding beams 14a, 14b during the motion of the MEMS actuator. Because the bending stiffness of the out-of-plane motion suppression structure is greater than the torsional stiffness of the folding beam, the stroke of the MEMS actuator can be greatly increased. This can be achieved by calculating the force analysis of the out-of-plane motion suppression structure and the folding beam and adjusting the size (e.g., length, width or thickness) of each component of the frame structure.

[0079] The driving structure 20 is connected to the frame structure 10 for providing power to the frame structure 10. The integrated lens structure 30 is rigidly connected to the micro-motion platform 11. In the embodiment, as shown in Figure 2 and Figure 3 , the driving structure 20 comprises a permanent magnet 21 and a power coil 22. The permanent magnet 21 is bonded in the micro-motion platform 11, the integrated lens structure 30 is bonded in the permanent magnet 21, and the integrated lens structure 30 is surrounded by the permanent magnet 21. The power coil 22 is located below the frame structure 10.

[0080] In the embodiment, as shown in Figure 2 and Figure 3 , the permanent magnet 21 is annular, and the polarization direction is perpendicular to the power coil 22, Figure 3 which is perpendicular to the direction of the paper. The integrated lens structure 30 is surrounded by the permanent magnet 21. The power coil 22 comprises a first power coil 22a and a second power coil 22b. The first power coil 22a and the second power coil 22b are electrically connected through an interconnection line 23, and the first power coil 22a and the second power coil 22b and the interconnection line 23 are connected through a through hole 24. The first power coil 22a and the second power coil 22b are designed to rotate in opposite directions under the magnetic field of the permanent magnet 21 after being powered, so that the same direction current is formed in the middle position of the first power coil 22a and the second power coil 22b, so that the driving force provided by the first power coil 22a and the second power coil 22b to the permanent magnet 21 is in the same direction, thereby improving the current-force conversion efficiency of the MEMS actuator. As shown in Figure 3 , the first power coil 22a and the second power coil 22b form downward current in the middle position. Figure 3 In the figure, the hollow arrow represents the current direction of the first power coil 22a and the second power coil 22b, and the black solid arrow represents the ampere force direction of the first power coil 22a and the second power coil 22b, that is, the opposite direction of the force of the permanent magnet 21 and the frame structure 10.

[0081] The first power coil 22a and the second power coil 22b have a first gap A, as shown in Figure 2 and Figure 3 , the first gap A is aligned with the integrated lens structure 30, thereby forming an optical path.

[0082] In other embodiments of the present application, the driving structure can also be other structures as long as the corresponding technical effects can be achieved.

[0083] The integrated lens structure 30 is bonded in the micro-motion platform. In the embodiment, the integrated lens structure 30 is bonded in the permanent magnet 21, which significantly reduces the length, width and thickness of the device. In the present application, the integrated lens structure 30 is the payload, and under the excitation of the magnetic field, the micro-motion platform 11 can drive the integrated lens structure 30 to move in the length and width directions parallel to the paper plane, thereby realizing the function of beam scanning.

[0084] In the embodiment, the MEMS actuator further includes a spacer 40 and a tube structure 50. In other embodiments of the present application, the MEMS actuator can also not include the spacer 40 and the tube structure 50.

[0085] As shown in Figure 2 , the spacer 40 is located between the energized coil 22 and the frame structure 10 and is bonded with the frame structure 10 for supporting the frame structure 10. As shown in Figure 1 , in the present application, a fourth connecting block 16e is further arranged on the second-1 folded beam 14a and the second-2 folded beam 14b, and the fourth connecting block 16e is used for bonding with the spacer 40. The fourth connecting block 16e connects the second-1 folded beam 14a and the second-2 folded beam 14b and the spacer 40, wherein the spacer 40 is rigidly connected with the tube structure 50, and the spacer 40 and the tube structure 50 together constitute a fixed end rack. Optionally, the spacer 40 is made of BF33 glass. The BF33 glass spacer can be accurately processed by using laser cutting technology to ensure its accurate fit with other components.

[0086] The tube structure 50 is located below the energized coil 22 for supporting the energized coil 22. In the embodiment, the energized coil 22 is integrated in the tube structure 50, which has the functions of mechanical support, optical access and electromagnetic drive, thereby significantly improving the electromagnetic drive efficiency and reducing the device size. The overall size of the energized coil 22 is consistent with the size of the space formed by the internal electrical connection pins of the tube structure 50, as shown in Figure 3 , the internal electrical connection pins of the tube structure 50 can be fixed and electrically connected with the pins 25 of the energized coil 22 by brazing method.

[0087] As shown in Figure 2 , the part of the tube structure 50 aligned with the integrated lens structure 30 has a second gap B, and the first gap A and the second gap B overlap, thereby forming an optical access.

[0088] The MEMS actuator provided by this application has significantly improved stiffness. In one embodiment of this application, the displacement of the MEMS actuator is 2.2 microns when a force of 200 micronewtons is applied to the micro-motion platform. In a comparative example of this application, the displacement of an actuator without an out-of-plane motion suppression structure (the only difference from the MEMS actuator of this application is that it does not have an out-of-plane motion suppression structure) is 3.7 microns. This means that the in-plane stiffness of the MEMS actuator provided by this application is 91 Newtons / meter, while the stiffness of the comparative example actuator is 54 Newtons / meter, which is 68.5% higher than the latter.

[0089] The actuators of the aforementioned embodiments were also tested for off-plane stiffness stability at various Y-axis (i.e., the widthwise axis parallel to the paper). The results showed that the off-plane stiffness of the MEMS actuators provided in this application, when loaded at various locations, varied by no more than 5 N / m, representing 6% of the total stiffness (91 N / m), demonstrating excellent stiffness stability and platform torsion suppression.

[0090] Figure 4 A method for preparing the above-mentioned MEMS actuator provided in an embodiment of the present application is shown, including steps S1 to S3.

[0091] S1: Prepare the framework structure.

[0092] like Figure 5 As shown, step S1 may include:

[0093] S10: photolithographically etching the shape of the frame structure on the substrate; and

[0094] S20: etching the substrate to obtain a framework structure.

[0095] In one embodiment of the present application, Figure 6 As shown, step S10 may include sub-steps S11 to S15, and step S20 may include sub-steps S21 to S23.

[0096] S11: A metal film FIL is deposited on the back side of a first substrate SUB1. Optionally, the first substrate SUB1 is a silicon wafer. The size of the silicon wafer can be set according to actual needs, for example, a four-inch diameter and a thickness of 200 microns. Optionally, the silicon wafer is single crystal silicon, which has excellent mechanical properties and thermal stability. Before depositing the metal film FIL, the silicon wafer surface can be cleaned and treated to ensure that the resist is evenly coated on the silicon wafer during the photolithography process.

[0097] S12: Apply photoresist GLU on the metal film FIL, and then expose the photoresist GLU coated on the metal film FIL without mask shielding. The photoresist GLU can be uniformly coated on the surface of the silicon wafer by using spin coating technology, and then the solvent in the photoresist GLU is removed by soft baking process. The silicon wafer can be exposed by using ultraviolet light, so that the photoresist GLU chemically reacts in the predetermined area.

[0098] S13: The shape of the frame structure 10 is photoetched on the front surface of the first substrate SUB1. The unexposed photoresist GLU can be removed by using developing solution, leaving a pattern corresponding to the design pattern (i.e. the pattern of the frame structure 10).

[0099] S14: Apply adhesive ADV on the front surface of the second substrate SUB2. The adhesive ADV can be a temporary adhesive. The temporary adhesive can be uniformly coated on the surface of the second substrate SUB2 by using spin coating technology. The material of the second substrate SUB2 can be selected according to actual needs.

[0100] S15: The front surface of the second substrate SUB2 is bonded to the back surface of the first substrate SUB1 by the adhesive ADV.

[0101] S21: Etch the front surface of the first substrate SUB1 according to the shape of the frame structure 10, until the metal film FIL of the back surface of the first substrate SUB1 is exposed. Deep silicon etching technology (such as deep reactive ion etching (DRIE) technology, which can realize high aspect ratio silicon structure etching) can be used to accurately etch the silicon wafer according to the pattern defined in the photoetching step (the gas flow, temperature and pressure lamp of the etching process can be controlled to ensure that the size and shape of the structure meet the design requirements), thereby obtaining the frame structure 10.

[0102] S22: Separate the second substrate SUB2 from the first substrate SUB1. As shown in Figure 5 , after separation, only the first substrate SUB1 and the metal film FIL remain. The second substrate SUB2 can be separated from the first substrate SUB1 by laser debonding method.

[0103] S23: Remove the metal film FIL of the separated first substrate SUB1. As shown in Figure 5 , the frame structure 10 is obtained after separation. Ethanol-hydrochloric acid solution can be used to remove the metal film FIL of the separated first substrate SUB1, in which the ethanol solution is used to remove the residue on the back surface of the metal film FIL, and the hydrochloric acid is used to remove the metal film FIL.

[0104] S2: Connect the driving structure to the frame structure.

[0105] Optionally, step S2 includes:

[0106] bonding the permanent magnet 21 in the micro-motion platform 11; and

[0107] attaching the first energized coil 22a and the second energized coil 22b under the frame structure 10, and aligning the first gap A with the integrated lens structure 30.

[0108] After the installation, the polarization direction of the permanent magnet 21 is perpendicular to the energized coil 22, and the rotation directions of the first energized coil 22a and the second energized coil 22b after energization are opposite in the magnetic field of the permanent magnet 21.

[0109] S3: rigidly connecting the integrated lens structure and the micro-motion platform.

[0110] Optionally, the step S3 comprises:

[0111] bonding the integrated lens structure 30 in the permanent magnet 21 and being surrounded by the permanent magnet 21.

[0112] Figure 4 The method shown further comprises a step S4, which is performed after the step S3. In some embodiments of the present application, the step S4 can also be not included.

[0113] S4: assembling the spacer, the tube structure and the frame structure.

[0114] The tube structure 50 has a second gap B. After the assembly, the spacer 40 is located between the energized coil 22 and the frame structure 10, and is bonded with the frame structure 10. After the assembly, the energized coil 22 is integrated in the tube structure 50, and the second gap B is aligned with the integrated lens structure 30. The second gap B overlaps the first gap A.

[0115] The preparation method provided by the present application is precise in process, and the MEMS actuator prepared by the method has large out-of-plane motion stiffness and excellent performance.

[0116] The present application also provides applications of the above-mentioned MEMS actuator in a light beam steering system, an optical image stabilizer, an atomic force microscope and / or cell operation. The MEMS actuator can effectively provide two degrees of freedom of stable and precise motion in the length direction and the width direction in the plane of the paper in the sub-millimeter range, and realize precise motion function in a small volume.

[0117] Reference in the specification to any feature, advantage or similar language does not imply that all of the features and advantages that can be realized from the present solution should be or are contained in or covered by any single implementation of the present solution. Rather, language referring to features and advantages is understood to mean that a specific feature, advantage, or characteristic is included in at least one implementation of the present solution. Accordingly, discussion of features, advantages, and similar language throughout the specification can, but does not necessarily, refer to the same embodiment.

[0118] Furthermore, the features, advantages, and properties of the present aspects can be combined in any suitable manner in one or more embodiments. Those skilled in the relevant art will recognize, in light of the description herein, that the present aspects can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages can be recognized in light of the

[0119] The above describes the embodiments of the present application in detail, and the principles and implementation manners of the present application are described by applying specific examples. The above embodiment descriptions are only used to help understand the method of the present application and its core idea. Meanwhile, the changes or deformations made by the person skilled in the art according to the idea of the present application, based on the specific implementation manners and application scope of the present application, all belong to the protection scope of the present application. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A MEMS actuator, characterized in that: include: Framework structure, including: A connecting structure comprising a first connecting block, a second connecting block, a third connecting block and a connecting frame; Micro-motion platform; a pair of first folding beams, each connected to the micro-motion platform through the first connecting block and connected to the connecting frame through the second connecting block; a pair of first out-of-plane motion suppression structures, respectively connected to each first folding beam to form a first closed structure; the micro-motion platform is surrounded by the first closed structure, and the first closed structure is surrounded by the connecting frame; a pair of second folding beams, connected to the connecting frame respectively through the third connecting blocks, wherein the arrangement direction of the pair of second folding beams is orthogonal to the arrangement direction of the pair of first folding beams; and a pair of second out-of-plane motion suppression structures, respectively connected to each second folding beam to form a second closed structure; the frame structure is surrounded by the second closed structure; a driving structure connected to the frame structure and configured to provide power to the frame structure; and An integrated lens structure is rigidly connected to the micro-motion platform; The first connection points where the pair of first out-of-plane motion suppression structures are connected to the pair of first folded beams satisfy the following conditions: when the pair of first out-of-plane motion suppression structures are not present, the pair of first folded beams can undergo common-mode motion at the first connection points if subjected to a force parallel to a first plane of the first closed structure, and can undergo differential-mode motion at the first connection points if subjected to a force perpendicular to the first plane; The second connection points where the pair of second out-of-plane motion suppression structures are connected to the pair of second folding beams satisfy the following conditions: when the pair of second out-of-plane motion suppression structures do not exist, if the pair of second folding beams are subjected to a force parallel to the second plane of the second closed structure, common-mode motion can occur at the second connection points, and if they are subjected to a force in a direction perpendicular to the second plane, differential-mode motion can occur at the second connection points.

2. The MEMS actuator according to claim 1, wherein: During movement of the MEMS actuator, the bending stiffness of the pair of first out-of-plane motion suppression structures and the pair of second out-of-plane motion suppression structures is greater than the torsional stiffness of the one-to-one folded beams and the pair of second folded beams; and / or The first connection point is a bent end of each first folding beam, and the second connection point is a bent end of each second folding beam.

3. The MEMS actuator according to claim 1, wherein: The driving structure includes a permanent magnet and an energized coil. The permanent magnet is bonded to the micro-motion platform. The integrated lens structure is bonded to the permanent magnet and is surrounded by the permanent magnet. The energized coil is located under the frame structure.

4. The MEMS actuator according to claim 3, wherein: The permanent magnet is annular, and its polarization direction is perpendicular to the energized coil; The energized coil includes a first energized coil and a second energized coil. After being energized, the first energized coil and the second energized coil rotate in opposite directions under the magnetic field of the permanent magnet. There is a first gap between the first energized coil and the second energized coil, and the first gap is aligned with the integrated lens structure to form an optical path.

5. The MEMS actuator according to claim 3, wherein: Also includes: a spacer, located between the energized coil and the frame structure and bonded to the frame structure to support the frame structure; as well as a tube shell structure, used for supporting the energized coil, wherein the energized coil is integrated; A portion of the housing structure aligned with the integrated lens structure has a second gap, thereby forming the optical path.

6. A method for preparing the MEMS actuator according to any one of claims 1 to 5, characterized in that: include: The preparation of the framework structure comprises: photolithography the shape of the frame structure on a substrate; and etching the substrate to obtain the framework structure; connecting the drive structure to the frame structure; and The integrated lens structure is rigidly connected to the micro-motion platform.

7. The method according to claim 6, characterized in that Photoetching the shape of the frame structure on the substrate comprises: depositing a metal film on the back side of the first substrate; Coating a photoresist on the metal film, and then exposing the photoresist coated on the surface of the metal film without a mask; Photoetching the shape of the frame structure on the front surface of the first substrate; Applying an adhesive to the front surface of the second substrate; and bonding the front surface of the second substrate and the back surface of the first substrate together with an adhesive; Etching the substrate to obtain the framework structure comprises: etching the front surface of the first substrate according to the shape of the frame structure until the metal film on the back surface of the first substrate is exposed; separating the second substrate from the first substrate; and The metal film on the separated first substrate is removed.

8. The method according to claim 6, characterized in that The driving structure includes a permanent magnet and a powered coil, wherein the polarization direction of the permanent magnet is perpendicular to the powered coil; the powered coil includes a first powered coil and a second powered coil, wherein the first powered coil and the second powered coil rotate in opposite directions under the magnetic field of the permanent magnet after being energized; and a first gap is defined between the first powered coil and the second powered coil; Connecting the drive structure to the frame structure includes: Bonding the permanent magnet into the micro-motion platform; and Attaching the first powered coil and the second powered coil under the frame structure so that the first gap is aligned with the integrated lens structure; Forming a rigid connection between the integrated lens structure and the micro-motion platform includes: The integrated lens structure is bonded into the permanent magnet and surrounded by the permanent magnet.

9. The method according to claim 8, characterized in that The MEMS actuator further includes a spacer and a shell-and-tube structure, wherein the shell-and-tube structure has a second gap, and the method further includes: Assemble the spacer, the shell structure and the frame structure so that the spacer is located between the powered coil and the frame structure and bonded to the frame structure, and the powered coil is integrated into the shell structure and the second gap is aligned with the integrated lens structure.

10. Use of the MEMS actuator according to any one of claims 1 to 5 in a beam steering system, an optical image stabilizer, an atomic force microscope and / or cell manipulation.

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