Multistage-driven MEMS electrostatic actuator

Abstract

The present invention provides a multi-stage driven MEMS electrostatic actuator, the structure of which includes: a substrate, a payload, a plurality of one-dimensional electrostatic drive structures connected in series step by step, an anchor, a wire, and an insulating medium; each one-dimensional electrostatic drive structure of each stage includes an outer frame, at least one electrostatic drive unit, and at least one elastic beam; the payload is connected to the outer frame of the first stage; except that the outer frame of the last stage is suspended and fixed to the substrate through the elastic beam of the last stage, the outer frame of each of the remaining stages is connected to the outer frame of the next stage through the elastic beam of the same stage; the electrostatic drive unit includes two sets of comb teeth opposite in position, which are respectively arranged on the outer frame of the same stage and the substrate or the outer frame of the next stage; the outer frame of each stage realizes one-dimensional movement independently under the action of the electrostatic drive unit of the same stage; under the combined action of the one-dimensional electrostatic drive structures of each stage, the payload realizes multi-dimensional movement or / and large-displacement movement without coupling interference.

Description

Technical Field

[0001] The present invention belongs to the field of microelectromechanics, and particularly relates to a multi-stage driven MEMS electrostatic actuator. Background Art

[0002] MEMS (Micro-Electro-Mechanical System) refers to a micro-integrated device or system that realizes the functions of an electromechanical system on a semiconductor chip by using micro-machining technology and integrated circuit manufacturing technology. It has been widely used in various fields of social production and life and is the main technology in the so-called "Beyond Moore" route of semiconductor technology. As a component for MEMS to output actions and / or functions externally, the MEMS actuator is both one of the basic functional units in MEMS devices and an important application direction of MEMS technology like MEMS sensors. Therefore, it has always been the research focus of MEMS technology, and successful applications include digital micromirror (DMD), inkjet print head, optical switch, RF switch, micro relay, micro microphone, etc. Among many driving principles, electrostatic driving has become the most main driving method for MEMS actuators due to its advantages such as precise control, good driving repeatability, easy implementation, and low power consumption.

[0003] For different application requirements, the MEMS electrostatic actuator needs to provide one-dimensional or multi-dimensional driving. The driving directions include translation along the X / Y / Z directions and torsion around the X / Y / Z axes, with a total of six degrees of freedom (if the chip is in the XY plane, translation along the X / Y directions and torsion around the Z axis are called in-plane motions, and translation along the Z direction and torsion around the X / Y axes are called out-of-plane motions). Compared with one-dimensional driving, in addition to the more complex structure and processing technology for multi-dimensional driving, the coupling interference between different driving directions is the main factor restricting high-precision independent driving, that is, the driving in one direction will affect the driving effect in another direction, bringing great difficulties to driving control. The MEMS three-dimensional actuator with the most reported driving directions so far (Wu Lei, et al. A Tip-Tilt-Piston Micromirror Array for Optical Phased Array Applications. JMEMS 19.6: 1450 - 1461) is a composite actuator that twists around the X / Y axes and translates along the Z direction (also called a Tip-Tilt-Piston (TTP) actuator); this three-dimensional multi-stage driven MEMS actuator uses the motion synthesis of four single-axis torsion actuators without a rotating shaft to form the three-dimensional motion of TTP. Therefore, there is inevitably coupling crosstalk between the three axes of TTP, making it difficult to achieve independent driving and the driving control is very complex.

[0004] In addition, limited by the energy density and structural size of the driving material / structure, MEMS electrostatic actuators can often only achieve translational displacements of a few microns to more than ten microns, or torsional angular displacements of a few tenths of a degree to a few degrees. It is technically very difficult to achieve larger translational displacements and larger torsional angular displacements, which severely limits the application of multi-stage driven MEMS actuators.

[0005] Therefore, how to solve the problems of inter-axis coupling and small displacement in existing MEMS electrostatic actuators has become one of the problems that technical personnel in this field need to solve urgently. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a multi-stage driven MEMS electrostatic actuator to solve the problems of inter-axis coupling interference and inability to achieve large displacement in the prior art.

[0007] To achieve the above and other related objectives, the present invention provides a multi-stage driven MEMS actuator, comprising: a substrate, a payload, a plurality of one-dimensional electrostatic drive structures connected in series step by step, an anchor, a wire, and an insulating medium; each one-dimensional electrostatic drive structure of each stage includes an outer frame, at least one electrostatic drive unit, and at least one elastic beam; the outer frame of the last stage is connected to one end of the elastic beam of the last stage, and is connected to the anchor through the other end of the elastic beam of the last stage, and is suspended and fixed on the substrate; the outer frame of each of the remaining stages is connected to the outer frame of the next stage through the elastic beam of the same stage; the payload is connected to the outer frame of the first stage; each electrostatic drive unit of each stage includes two sets of comb teeth opposite in position, namely an inner comb tooth set and an outer comb tooth set; the inner comb tooth set of each electrostatic drive unit of each stage is arranged on the outer frame of the same stage; the outer comb tooth set of each electrostatic drive unit of each stage is arranged on the outer frame of the next stage, and the outer comb tooth set of the electrostatic drive unit of the last stage is arranged on the substrate; each electrostatic drive unit of each stage drives the outer frame of the same stage to independently achieve one-dimensional motion; under the combined action of the one-dimensional electrostatic drive structures of each stage, the payload achieves multi-dimensional motion or / and large-displacement motion without coupling interference; except for the payload, the remaining structures of the multi-stage driven MEMS electrostatic actuator are stacked by three body structure layers and several thin film layers; the three body structure layers are respectively a bottom body structure layer, an intermediate body structure layer, and a top body structure layer; the substrate exclusively occupies the bottom body structure layer; all the outer frames, all the elastic beams, and the anchor are disposed on the intermediate body structure layer or all are disposed on the top body structure layer, forming a main continuous structure; a conductive thin film layer and an intermediate insulating thin film layer are arranged between the intermediate body structure layer and the top body structure layer; the wire is disposed on the conductive thin film layer; the intermediate insulating thin film layer is used to provide the insulating medium.

[0008] Optionally, in the initial state, the vertical projections of the inner comb tooth set and the outer comb tooth set of the electrostatic drive unit on the substrate are in an interdigitated distribution.

[0009] Optionally, when the one-dimensional motion provided by the one-dimensional electrostatic drive structure is out-of-plane torsion or out-of-plane translation, the inner comb tooth set and the outer comb tooth set of the corresponding electrostatic drive unit are disposed on different body structure layers.

[0010] Optionally, when the one-dimensional motion provided by the one-dimensional electrostatic drive structure is in-plane torsion or in-plane translation, the inner comb tooth set and the outer comb tooth set of the corresponding electrostatic drive unit are both disposed on a body structure layer that does not include the main continuous structure.

[0011] More optionally, both of the two comb tooth sets in the electrostatic drive unit are insulated from the main body continuous structure; or one of the comb tooth sets is insulated from the main body continuous structure, and the other comb tooth set is electrically connected to the main body continuous structure through the wire.

[0012] Optionally, except for the outer comb tooth set of the last stage, the drive voltages of the comb tooth sets insulated from the main body continuous structure are all led to the surface of the anchor point through the wire, and the wire and the main body continuous structure are always separated by the insulating medium.

[0013] Optionally, when the outer comb tooth set of the last stage is arranged on the top body structure layer, a comb tooth set support seat is arranged below the outer comb tooth set of the last stage for supporting and fixing the outer comb tooth set of the last stage; the comb tooth set support seat is stacked by a structure partially arranged on the intermediate body structure layer, the conductive thin film layer and the intermediate insulating thin film layer.

[0014] Optionally, when the main body continuous structure is arranged on the top body structure layer, an anchor point support seat is arranged below the anchor point for supporting and fixing the anchor point; the anchor point support seat is arranged on the intermediate body structure layer.

[0015] Optionally, blind holes or through holes are processed on the substrate to provide a movement space for each stage of the one-dimensional electrostatic drive structure.

[0016] Optionally, the material of the bottom body structure layer is glass, silicon or metal; the material of the intermediate body structure layer is silicon or metal; the material of the top body structure layer is silicon or metal; the material of the conductive thin film layer is metal; the material of the intermediate insulating thin film layer is inorganic insulating material or organic insulating material.

[0017] Optionally, the bottom body structure layer is in direct contact with the intermediate body structure layer; or a bottom insulating thin film layer is arranged between the bottom body structure layer and the intermediate body structure layer for providing the insulating medium.

[0018] More optionally, the material of the bottom insulating thin film layer is inorganic insulating material or organic insulating material.

[0019] Optionally, the load is integrally processed with the multi-stage driven MEMS electrostatic driver; or after the multi-stage driven MEMS electrostatic driver is processed, the load is fixed to the outer frame of the first stage, and the fixing method is pasting, welding or bonding; or a part of the structure of the load is integrally processed with the multi-stage driven MEMS electrostatic driver, and the other part of the structure is fixed to the outer frame of the first stage after the multi-stage driven MEMS electrostatic driver is processed, and the fixing method is pasting, welding or bonding.

[0020] As described above, the multi-stage driven MEMS electrostatic actuator provided by the present invention has the following beneficial effects:

[0021] 1. In the multi-stage driven MEMS electrostatic actuator of the present invention, the one-dimensional electrostatic drive structure of each stage is a follower structure of the one-dimensional electrostatic drive structure of the next stage. Therefore, the drive shafts of the one-dimensional electrostatic drive structures of each stage are physically isolated from each other, eliminating the interference of inter-axis coupling, and finally realizing multi-axis electrostatic drive without inter-axis coupling.

[0022] 2. In the multi-stage driven MEMS electrostatic actuator of the present invention, the one-dimensional electrostatic drive structure of each stage is a follower structure of the one-dimensional electrostatic drive structure of the next stage. Therefore, by connecting in series a plurality of one-dimensional electrostatic drive structures with the same driving direction, electrostatic drive with large displacement can be realized.

[0023] 3. In the multi-stage driven MEMS electrostatic actuator of the present invention, by arranging wires on the surface of the structure, the lead problem of the one-dimensional electrostatic drive structures except the last stage is solved.

[0024] 4. The multi-stage driven MEMS electrostatic actuator of the present invention is stacked by three body structure layers and several thin film layers. Its structural design and processing technology are relatively simple, which is conducive to mass production using MEMS technology. Description of the Drawings

[0025] Figure 1 It shows a three-dimensional structural schematic diagram of Embodiment 1 of the multi-stage driven MEMS electrostatic actuator of the present invention.

[0026] Figure 2 It shows Figure 1 an exploded structural schematic diagram of the multi-stage driven MEMS electrostatic actuator in

[0027] Figure 3 It shows Figure 1 a top view schematic diagram of the multi-stage driven MEMS electrostatic actuator in

[0028] Figure 4 It shows Figure 1 a cross-sectional structural schematic diagram of the multi-stage driven MEMS electrostatic actuator in along a plane perpendicular to the torsion shaft.

[0029] Figure 5A It shows a three-dimensional structural schematic diagram of Embodiment 2 of the multi-stage driven MEMS electrostatic actuator of the present invention.

[0030] Figure 5B It shows a three-dimensional structural schematic diagram of Embodiment 2 of the multi-stage driven MEMS electrostatic actuator of the present invention (with some loads removed).

[0031] Figure 6 Shown as Figure 5A Schematic cross-sectional view of the multi-stage driven MEMS electrostatic actuator along the torsion axis of the third stage.

[0032] Figure 7 Shown as Figure 5B Exploded schematic view of the multi-stage driven MEMS electrostatic actuator (partial load removed).

[0033] Figure 8 Shown as Figure 5B Top view schematic of the multi-stage driven MEMS electrostatic actuator (partial load removed).

[0034] Component label description

[0035] 10 Mirror body

[0036] 11 Support rod

[0037] 12 Load fixing structure

[0038] 13 Load fixing platform

[0039] 21 Outer frame of the first stage

[0040] 22 Elastic beam of the first stage

[0041] 23 Outer comb tooth set of the first stage

[0042] 24 Inner comb tooth set of the first stage

[0043] 25 Torsion axis of the first stage

[0044] 31 Outer frame of the second stage

[0045] 32 Elastic beam of the second stage

[0046] 33 Outer comb tooth set of the second stage

[0047] 34 Inner comb tooth set of the second stage

[0048] 35 Torsion axis of the second stage

[0049] 41 Outer frame of the third stage

[0050] 42 Elastic beam of the third stage

[0051] 43 Outer comb tooth set of the third stage

[0052] 44 Inner comb tooth set of the third stage

[0053] 45 Torsion axis of the third stage

[0054] 50 Substrate

[0055] 51 Anchor point

[0056] 52 Conducting wire

[0057] 53 Insulating medium

[0058] 54 Comb tooth set support base

[0059] 101 Bottom body structure layer

[0060] 102 Intermediate body structure layer

[0061] 103 Top body structure layer

[0062] 104 Conductive thin film layer

[0063] 105 Intermediate insulating thin film layer

[0064] 106 Bottom insulating thin film layer Detailed implementation manners

[0065] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0066] Please refer to Figures 1 to 8 Note that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Although only the components related to the present invention are shown in the diagrams and are not drawn according to the number, shape, and size of the components in actual implementation, the actual form, quantity, and ratio of each component during actual implementation can be arbitrarily changed, and the layout form of its components may also be more complex.

[0067] Embodiment 1

[0068] As Figure 1As shown in the figure, this embodiment provides a multi-stage driven MEMS electrostatic actuator, including: a payload (composed of a mirror body 10 and two payload fixing structures 12), a substrate 50, two one-dimensional electrostatic drive structures connected in series step by step (wherein, the one-dimensional electrostatic drive structure of the first stage includes a first-stage outer frame 21, two first-stage electrostatic drive units and two first-stage elastic beams 22, and the one-dimensional electrostatic drive structure of the second stage includes a second-stage outer frame 31, two second-stage electrostatic drive units and two second-stage elastic beams 32), two anchor points 51, a wire 52 and an insulating medium 53. Among them, each first-stage electrostatic drive unit includes a first-stage outer comb tooth set 23 and a first-stage inner comb tooth set 24, and each second-stage electrostatic drive unit includes a second-stage outer comb tooth set 33 and a second-stage inner comb tooth set 34.

[0069] As Figure 2 shown, except for the payload, the remaining structures of the multi-stage driven MEMS electrostatic actuator are stacked by three body structure layers and two thin film layers. The three body structure layers are a bottom body structure layer 101, an intermediate body structure layer 102 and a top body structure layer 103 respectively. The two thin film layers are arranged between the intermediate body structure layer 102 and the top body structure layer 103, and are a conductive thin film layer 104 and an intermediate insulating thin film layer 105 respectively. Among them, the intermediate insulating thin film layer 105 is arranged between the conductive thin film layer 104 and the intermediate body structure layer 102. In addition, the intermediate body structure layer 102 is in direct contact with the bottom body structure layer 101. Among them, the material of the bottom body structure layer 101 is glass, the materials of the intermediate body structure layer 102 and the top body structure layer 103 are both silicon, the material of the conductive thin film layer 104 is gold, and the material of the intermediate insulating thin film layer 105 is silicon dioxide.

[0070] As Figure 2 shown, the substrate 50 exclusively occupies the bottom body structure layer 101. The first-stage outer frame 21, two first-stage elastic beams 22, the second-stage outer frame 31, two second-stage elastic beams 32 and two anchor points 51 are all arranged on the intermediate body structure layer 102, forming a main continuous structure. Two first-stage outer comb tooth sets 23 and two second-stage outer comb tooth sets 33 are both arranged on the intermediate body structure layer 102; among them, the two first-stage outer comb tooth sets 23 and the main continuous structure form an integrated structure. Two first-stage inner comb tooth sets 24 and two second-stage inner comb tooth sets 34 are both arranged on the top body structure layer 103. The wire 52 is arranged on the conductive thin film layer 104, and the insulating medium 53 is arranged on the intermediate insulating thin film layer 105. In addition, the mirror body 10 and the two payload fixing structures 12 in the payload are also both arranged on the intermediate body structure layer 102, and among them, the payload is integrally processed with this multi-stage driven MEMS electrostatic actuator.

[0071] As Figure 1 andFigure 2 As shown, both ends of the mirror body 10 are respectively connected to a load fixing structure 12, which is connected to the outer frame 21 of the first stage.

[0072] As Figure 1 and Figure 2 shown, both sides of the outer frame 31 of the second stage are respectively connected to an elastic beam 32 of the second stage, and are suspended and fixed on the substrate 50 through the anchor points 51 at the other ends of the elastic beams 32 of the second stage. The two elastic beams 32 of the second stage are used to provide the outer frame 31 of the second stage with a torsional degree of freedom around the torsional axis 35 of the second stage. On both sides of the torsional axis 35 of the second stage, a second-stage electrostatic driving unit is respectively arranged, which is used to drive the outer frame 31 of the second stage to twist around the torsional axis 35 of the second stage. Among them, both sets of second-stage outer comb teeth 33 are fixed on the substrate 50; both sets of second-stage inner comb teeth 34 are fixed on the outer frame 31 of the second stage, but are insulated from the outer frame 31 of the second stage, and thus are insulated from the main body continuous structure.

[0073] As Figure 1 and Figure 2 shown, both sides of the outer frame 21 of the first stage are respectively connected to an elastic beam 22 of the first stage, and are connected to the outer frame 31 of the second stage through the other ends of the elastic beams 22 of the first stage, so as to be suspended and fixed on the outer frame 31 of the second stage. The two elastic beams 22 of the first stage are used to provide the outer frame 21 of the first stage with a torsional degree of freedom around the torsional axis 25 of the first stage; in addition, the torsional axis 25 of the first stage coincides with the torsional axis 35 of the second stage. On both sides of the torsional axis 25 of the first stage, a first-stage electrostatic driving unit is respectively arranged, which is used to drive the outer frame 21 of the first stage to twist around the torsional axis 25 of the first stage. Among them, both sets of first-stage inner comb teeth 24 are fixed on the outer frame 21 of the first stage, but are insulated from the outer frame 21 of the first stage, and thus are insulated from the main body continuous structure.

[0074] Since the one-dimensional electrostatic driving structure of the first stage is arranged as a follow-up structure on the one-dimensional electrostatic driving structure of the second stage, the electrostatic driving of the first stage and the electrostatic driving of the second stage are physically isolated. The load can not only twist with the outer frame 21 of the first stage, but also twist with the outer frame 21 of the first stage and the outer frame 31 of the second stage together. Since the torsional axis 25 of the first stage coincides with the torsional axis 35 of the second stage, the torsional angle of the load is the sum of the respective torsional angles of the electrostatic driving of the first stage and the second stage, so its angular displacement is amplified.

[0075] As Figure 1 , Figure 2 and Figure 3As shown, the wire 52 is arranged on the surface of the main continuous structure through the insulating medium 53, and the driving voltage of the two first-level inner comb tooth sets 24 and the two second-level inner comb tooth sets 34 are led to the upper surface of the anchor point 51, thereby avoiding leading flying wires on the movable structure.

[0076] like Figure 3 As shown, initially, the vertical projections of the inner and outer comb teeth of each electrostatic drive unit on the substrate 50 are distributed in an interdigitated manner. Therefore, when voltage is applied to the inner and outer comb teeth in different body structure layers, an electrostatic force perpendicular to the upper surface of the substrate 50 is generated between the two.

[0077] like Figure 4 As shown, through holes are processed on the substrate 50 to provide activity space for the first-level one-dimensional electrostatic driving structure and the second-level one-dimensional electrostatic driving structure.

[0078] The multi-stage driven MEMS electrostatic actuator of this embodiment realizes driving of large displacement in a single direction by connecting multiple one-dimensional electrostatic driving structures in series step by step, and is conducive to mass production using MEMS technology.

[0079] Embodiment 2

[0080] like Figure 5A , Figure 5B , Figure 6 and Figure 7 As shown, this embodiment provides a multi-stage driven MEMS electrostatic actuator, including: a load (composed of a reflector body 10, a support rod 11 and a load fixing platform 13), a substrate 50, three one-dimensional electrostatic driving structures connected in series step by step (wherein the first-stage one-dimensional electrostatic driving structure includes a first-stage outer frame 21, four first-stage electrostatic driving units and four first-stage elastic beams 22, the second-stage one-dimensional electrostatic driving structure includes a second-stage outer frame 31, two second-stage electrostatic driving units and two second-stage elastic beams 32, and the third-stage one-dimensional electrostatic driving structure includes a third-stage outer frame 41, two third-stage electrostatic driving units and two third-stage elastic beams 42), two anchor points 51, two comb tooth set support seats 54, wires 52 and insulating media 53. Among them, each first-level electrostatic drive unit includes a first-level outer comb tooth set 23 and a first-level inner comb tooth set 24, each second-level electrostatic drive unit includes a second-level outer comb tooth set 33 and a second-level inner comb tooth set 34, and each third-level electrostatic drive unit includes a third-level outer comb tooth set 43 and a third-level inner comb tooth set 44.

[0081] like Figure 7As shown, except for the load, the remaining structure of the multi-stage driven MEMS electrostatic actuator is stacked by three body structure layers and three thin film layers. The three body structure layers are the bottom body structure layer 101, the intermediate body structure layer 102, and the top body structure layer 103 respectively. Two thin film layers are arranged between the intermediate body structure layer 102 and the top body structure layer 103, which are the conductive thin film layer 104 and the intermediate insulating thin film layer 105 respectively. A thin film layer, which is the bottom insulating thin film layer 106, is arranged between the intermediate body structure layer 102 and the bottom body structure layer 101. Among them, the materials of the bottom body structure layer 101, the intermediate body structure layer 102, and the top body structure layer 103 are all silicon, the material of the conductive thin film layer 104 is gold, and the materials of the intermediate insulating thin film layer 105 and the bottom insulating thin film layer 106 are both silicon dioxide.

[0082] As Figure 7 shown, the substrate 50 exclusively occupies the bottom body structure layer 101. The outer frame 21 of the first stage, four elastic beams 22 of the first stage, the outer frame 31 of the second stage, two elastic beams 32 of the second stage, the outer frame 41 of the third stage, two elastic beams 42 of the third stage, and two anchor points 51 are all arranged on the intermediate body structure layer 102, forming a main continuous structure. Four inner comb tooth sets 24 of the first stage, two inner comb tooth sets 34 of the second stage, and two inner comb tooth sets 44 of the third stage are all arranged on the intermediate body structure layer 102, and form an integrated structure with the main continuous structure. Four outer comb tooth sets 23 of the first stage, two outer comb tooth sets 33 of the second stage, and two outer comb tooth sets 43 of the third stage are all arranged on the top body structure layer 103. The wire 52 is arranged on the conductive thin film layer 104, and the insulating medium 53 is arranged on the intermediate insulating thin film layer 105 and the bottom insulating thin film layer 106. In addition, the load fixing platform 13 in the load is also arranged on the intermediate body structure layer 102 and is integrally processed with this multi-stage driven MEMS electrostatic actuator; the mirror body 10 and the support rod 11 in the load are pasted on the load fixing platform 13 after this multi-stage driven MEMS electrostatic actuator is processed.

[0083] As Figure 5B shown, the four sides of the load fixing platform 13 are respectively connected to the outer frame 21 of the first stage.

[0084] As Figure 5B and Figure 7As shown, on both sides of the outer frame 41 of the third level, an elastic beam 42 of the third level is respectively connected, and the other end of the elastic beam 42 of the third level is connected to the anchor point 51, and it is suspended and fixed on the substrate 50. The two elastic beams 42 of the third level are used to provide the torsional freedom of the outer frame 41 of the third level around the torsion axis 45 of the third level. On both sides of the torsion axis 45 of the third level, a third-level electrostatic driving unit is respectively arranged, which is used to drive the outer frame 41 of the third level to twist around the torsion axis 45 of the third level. Among them, the two outer comb tooth sets 43 of the third level are both fixed on the substrate 50. Since the outer comb tooth set 43 of the third level is arranged on the top body structure layer 103, a comb tooth set support base 54 is arranged below it; the comb tooth set support base 54 is stacked by a structure partially arranged in the intermediate body structure layer 102, the conductive thin film layer 104 and the intermediate insulating thin film layer 105.

[0085] As Figure 5B and Figure 7 shown, on both sides of the outer frame 31 of the second level, an elastic beam 32 of the second level is respectively connected, and the other end of the elastic beam 32 of the second level is connected to the outer frame 41 of the third level, so as to be suspended and fixed on the outer frame 41 of the third level. The two elastic beams 32 of the second level are used to provide the torsional freedom of the outer frame 31 of the second level around the torsion axis 35 of the second level. On both sides of the torsion axis 35 of the second level, a second-level electrostatic driving unit is respectively arranged, which is used to drive the outer frame 31 of the second level to twist around the torsion axis 35 of the second level. Among them, the two outer comb tooth sets 33 of the second level are fixed on the outer frame 41 of the third level, but are insulated from the outer frame 41 of the third level, and thus are insulated from the main body continuous structure.

[0086] As Figure 5B and Figure 7 shown, at the four corners of the outer frame 21 of the first level, an elastic beam 22 of the first level is respectively connected, and the other end of the elastic beam 22 of the first level is connected to the outer frame 31 of the second level, so as to be suspended and fixed on the outer frame 31 of the second level. The four elastic beams 22 of the first level are used to provide the translational freedom of the elastic beam 21 of the first level to translate along the Z axis. On the four sides of the outer frame 21 of the first level, a first-level electrostatic driving unit is respectively arranged, which is used to drive the outer frame 21 of the first level to translate along the Z axis. Among them, the four outer comb tooth sets 23 of the first level are fixed on the outer frame 31 of the second level, but are insulated from the outer frame 31 of the second level, and thus are insulated from the main body continuous structure.

[0087] Since the one-dimensional electrostatic drive structure of the first level is a follower structure and is arranged on the one-dimensional electrostatic drive structure of the second level, and the one-dimensional electrostatic drive structure of the second level is a follower structure and is arranged on the one-dimensional electrostatic drive structure of the third level, the electrostatic drive of the first level, the electrostatic drive of the second level and the electrostatic drive of the third level are physically isolated. The load can not only translate with the outer frame 21 of the first level, but also twist with the outer frame 31 of the second level together with the outer frame 21 of the first level, and also twist with the outer frame 41 of the third level together with the outer frame 21 of the first level and the outer frame 31 of the second level, thereby realizing three-dimensional electrostatic drive without inter-axial coupling interference.

[0088] like Figure 5A , Figure 5B , Figure 6 and Figure 7 As shown, the wire 52 is arranged on the surface of the main body continuous structure through the insulating medium 53, and the driving voltage of the four first-level outer comb tooth sets 23 and the two second-level outer comb tooth sets 33 is led to the upper surface of the anchor point 51, thereby avoiding the lead wire on the movable structure. Among them, the four first-level outer comb tooth sets 23 are electrically connected through the wire 52.

[0089] like Figure 8 As shown, initially, the vertical projections of the inner and outer comb teeth of each electrostatic drive unit on the substrate 50 are distributed in an interdigitated manner. Therefore, when voltage is applied to the inner and outer comb teeth in different body structure layers, an electrostatic force perpendicular to the upper surface of the substrate 50 is generated between the two.

[0090] like Figure 6 As shown, blind holes are processed on the substrate 50 to provide activity space for the first-level one-dimensional electrostatic driving structure, the second-level one-dimensional electrostatic driving structure and the third-level one-dimensional electrostatic driving structure.

[0091] The multi-stage driven MEMS electrostatic actuator of this embodiment realizes multi-dimensional electrostatic driving without inter-axis coupling by connecting multiple one-dimensional electrostatic driving structures in series step by step, and is conducive to mass production using MEMS technology.

[0092] In summary, this embodiment provides a multi-stage driven MEMS electrostatic actuator, including: a substrate, a payload, several one-dimensional electrostatic drive structures connected in series step by step, an anchor, a wire, and an insulating medium; each stage of the one-dimensional electrostatic drive structure includes an outer frame, at least one electrostatic drive unit, and at least one elastic beam; the outer frame of the last stage is connected to one end of the elastic beam of the last stage, and is connected to the anchor through the other end of the elastic beam of the last stage, and is suspended and fixed on the substrate; the outer frame of each of the remaining stages is connected to the outer frame of the next stage through the elastic beam of the same stage; the payload is connected to the outer frame of the first stage; each stage of the electrostatic drive unit includes two sets of comb teeth opposite in position, namely an inner comb tooth set and an outer comb tooth set; the inner comb tooth set of each stage of the electrostatic drive unit is arranged on the outer frame of the same stage; the outer comb tooth set of each stage of the electrostatic drive unit is arranged on the outer frame of the next stage, and the outer comb tooth set of the electrostatic drive unit of the last stage is arranged on the substrate; each stage of the electrostatic drive unit drives the outer frame of the same stage to independently achieve one-dimensional motion; under the combined action of the one-dimensional electrostatic drive structures of each stage, the payload achieves multi-dimensional motion or / and large-displacement motion without coupling interference; except for the payload, the remaining structures of the multi-stage driven MEMS electrostatic actuator are stacked by three body structure layers and several thin film layers; the three body structure layers are respectively a bottom body structure layer, an intermediate body structure layer, and a top body structure layer; the substrate exclusively occupies the bottom body structure layer; all the outer frames, all the elastic beams, and the anchor are provided on the intermediate body structure layer or all are provided on the top body structure layer, forming a main continuous structure; a conductive thin film layer and an intermediate insulating thin film layer are arranged between the intermediate body structure layer and the top body structure layer; the wire is provided on the conductive thin film layer; the intermediate insulating thin film layer is used to provide the insulating medium. In the multi-stage driven MEMS electrostatic actuator of the present invention, each stage of the one-dimensional electrostatic drive structure is a follower structure of the one-dimensional electrostatic drive structure of the next stage. Therefore, the drive shafts of each stage of the one-dimensional electrostatic drive structure are physically isolated from each other, eliminating the interference of inter-axis coupling, and finally achieving multi-dimensional motion or / and large-displacement motion without coupling interference. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0093] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A multi-stage driven MEMS electrostatic actuator, characterized in that it includes: a substrate, a load, a plurality of one-dimensional electrostatic drive structures connected in series step by step, an anchor, a wire and an insulating medium; each stage of the one-dimensional electrostatic drive structure includes an outer frame, at least one electrostatic drive unit and at least one elastic beam; the outer frame of the last stage is connected to one end of the elastic beam of the last stage, and is connected to the anchor through the other end of the elastic beam of the last stage, and is suspended and fixed on the substrate; the outer frame of each of the remaining stages is connected to the outer frame of the next stage through the elastic beam of the same stage; the load is connected to the outer frame of the first stage; each stage of the electrostatic drive unit includes two comb tooth sets opposite in position, namely an inner comb tooth set and an outer comb tooth set; the inner comb tooth set of each stage of the electrostatic drive unit is arranged on the outer frame of the same stage; the outer comb tooth set of each stage of the electrostatic drive unit is arranged on the outer frame of the next stage, and the outer comb tooth set of the electrostatic drive unit of the last stage is arranged on the substrate; each stage of the electrostatic drive unit drives the outer frame of the same stage to independently achieve one-dimensional motion; under the combined action of the one-dimensional electrostatic drive structures of each stage, the load achieves multi-dimensional motion or / and large-displacement motion without coupling interference; except for the load, the remaining structures of the multi-stage driven MEMS electrostatic actuator are stacked by three body structure layers and several thin film layers; the three body structure layers are respectively a bottom body structure layer, an intermediate body structure layer and a top body structure layer; the substrate exclusively occupies the bottom body structure layer; all the outer frames, all the elastic beams and the anchor are provided in the intermediate body structure layer or all are provided in the top body structure layer, forming a main body continuous structure; a conductive thin film layer and an intermediate insulating thin film layer are arranged between the intermediate body structure layer and the top body structure layer; the wire is arranged on the conductive thin film layer; the intermediate insulating thin film layer is used to provide the insulating medium.

2. The multi-stage driven MEMS electrostatic actuator according to claim 1, characterized in that: In the initial state, the inner comb tooth set and the outer comb tooth set of the electrostatic drive unit are in an interdigitated distribution in the vertical projection on the substrate.

3. The multi-stage driven MEMS electrostatic actuator according to claim 1, wherein: When the one-dimensional motion provided by the one-dimensional electrostatic drive structure is out-of-plane torsion or out-of-plane translation, the inner comb tooth set and the outer comb tooth set of the corresponding electrostatic drive unit are arranged in different body structure layers.

4. The multi-stage driven MEMS electrostatic actuator according to claim 1, characterized in that: When the one-dimensional motion provided by the one-dimensional electrostatic drive structure is in-plane torsion or in-plane translation, the inner comb tooth set and the outer comb tooth set of the corresponding electrostatic drive unit are both arranged in the body structure layer that does not include the main body continuous structure.

5. The multi-stage driven MEMS electrostatic actuator according to claim 4, characterized in that: Both comb tooth sets in the electrostatic drive unit are insulated from the main body continuous structure; or one of the comb tooth sets is insulated from the main body continuous structure, and the other comb tooth set is electrically connected to the main body continuous structure through the wire.

6. The multi-stage driven MEMS electrostatic actuator according to claim 1, wherein: Except for the outer comb tooth set of the last stage, the driving voltage of the comb tooth set insulated from the main body continuous structure is led to the surface of the anchor by the wire, and the wire and the main body continuous structure are always separated by the insulating medium.

7. The multi-stage driven MEMS electrostatic actuator according to claim 1, wherein: When the outermost comb tooth set of the last stage is disposed on the top body structure layer, a comb tooth set support base is arranged below the outermost comb tooth set of the last stage for supporting and fixing the outermost comb tooth set of the last stage; The comb tooth set support base is formed by stacking a structure partially disposed on the intermediate body structure layer, the conductive thin film layer, and the intermediate insulating thin film layer.

8. The multi-stage driven MEMS electrostatic actuator according to claim 1, wherein: When the main body continuous structure is disposed on the top body structure layer, an anchor support base is arranged below the anchor for supporting and fixing the anchor; The anchor support base is disposed on the intermediate body structure layer.

9. The multi-stage driven MEMS electrostatic actuator according to claim 1, characterized in that: Blind holes or through holes are machined on the substrate to provide a movement space for each stage of the one-dimensional electrostatic drive structure.

10. The multi-stage driven MEMS electrostatic actuator according to claim 1, wherein: The material of the bottom body structure layer is glass, silicon or metal; the material of the intermediate body structure layer is silicon or metal; the material of the top body structure layer is silicon or metal; the material of the conductive thin film layer is metal; the material of the intermediate insulating thin film layer is an inorganic insulating material or an organic insulating material.

11. The multi-stage driven MEMS electrostatic actuator according to claim 1, wherein: The bottom body structure layer is in direct contact with the intermediate body structure layer; or a bottom insulating thin film layer is arranged between the bottom body structure layer and the intermediate body structure layer for providing the insulating medium.

12. The multi-stage driven MEMS electrostatic actuator according to claim 11, wherein: The material of the bottom insulating thin film layer is an inorganic insulating material or an organic insulating material.

13. The multi-stage driven MEMS electrostatic actuator according to claim 1, wherein: The load is integrally processed with the multi-stage driven MEMS electrostatic actuator; or the load is fixed to the outermost frame of the first stage after the multi-stage driven MEMS electrostatic actuator is processed, and the fixing method is pasting, welding or bonding; or a part of the structure of the load is integrally processed with the multi-stage driven MEMS electrostatic actuator, and another part of the structure is fixed to the outermost frame of the first stage after the multi-stage driven MEMS electrostatic actuator is processed, and the fixing method is pasting, welding or bonding.

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