CN116300053A - Reverse-angle vertical comb micromirror driving structure, driving micromirror and preparation method thereof - Google Patents

Abstract

The invention discloses a reverse-angle vertical comb micromirror driving structure, a driving micromirror and a preparation method thereof, wherein the reverse-angle vertical comb micromirror driving structure comprises a main body and a cover plate covered on the main body; the cover plate comprises a cover plate substrate, and a dislocation activation boss and an inclination activation boss are fixed on the lower surface of the cover plate substrate; the main body comprises a stator anchor, fixed comb teeth, movable comb teeth and a main body substrate, wherein the fixed comb teeth extend from the stator anchor, and the stator anchor is connected with the main body substrate through a snake-shaped beam; the movable comb teeth and the fixed comb teeth are staggered with each other, and form a reverse angle vertical comb teeth micro mirror driving structure with the fixed comb teeth; when the cover plate and the main body are assembled, the misplacement activating lug boss presses down the part connected with the fixed comb teeth, so that the vertical height difference between the fixed comb teeth and the movable comb teeth is generated; the stator anchor is pressed down by the inclination angle activating boss, so that the fixed comb teeth are tilted. Compared with the AVC structure, the fixed comb teeth and the movable comb teeth have larger overlapping area, can provide larger attractive force, and has more obvious advantages as the rotation angle of the micromirror is larger.

Description

Reverse-angle vertical comb micromirror driving structure, driving micromirror and preparation method thereof

Technical Field

The invention belongs to the technical field of micro-electromechanical technology, and particularly relates to a reverse-angle vertical comb micromirror driving structure, a driving micromirror and a preparation method thereof.

Background

Microelectromechanical Systems (MEMS) technology is a technology that integrates functional modules, such as electronics, mechanics, and optics, into a microscale system based on microelectronics. The MEMS technology integrates a mechanical component, an optical system, a driving component and an electric control system into a whole unit, so that not only can information or instructions be acquired, processed and sent, but also actions can be taken according to the information. Compared with the traditional mechanical system, the system adopting the MEMS technology has the advantages of miniaturization, integration, low energy consumption, low cost, high precision, long service life, good dynamic property and the like.

MEMS micromirrors are an important optical device in microelectromechanical systems, and have found wide application in optical switches, projection displays, fiber optic sensing systems, and the like. With further improvement of MEMS processing technology, MEMS micromirrors are also gradually used as core scanning devices in some emerging application fields, such as laser radar systems, novel laser confocal microscopy systems, high-performance optical communication systems and the like.

MEMS micromirrors can be categorized into four types of electrostatic, electromagnetic, piezoelectric, and electrothermal actuation, depending on the actuation mode. Compared with the other three driving types, the electrostatic driving mode has the advantages of simple structure, low power consumption, high resonant frequency, complete compatibility of the preparation technology and the integrated circuit technology and the like, and is a research hotspot of a plurality of scientific research units at home and abroad. Currently, the electrostatic driving mode includes three structures of parallel flat plate driving, transverse comb tooth driving and vertical comb tooth driving, and each structure has respective advantages and disadvantages. The parallel flat plate structure adopts the earliest driving mode and the simplest driving mode, but the nonlinear driving force and the pull-down phenomenon severely restrict the working range and the application occasion of the micromirror. The transverse comb tooth structure has the characteristic of generating linear displacement in a plane in direct proportion to the driving voltage, and is suitable for generating in-plane translation or rotation; although torsion of the micromirror can also be achieved with this structure, the structure of the driver is also relatively complex and its resonant frequency is not high. The vertical comb teeth driving is formed by combining one or more pairs of movable and static comb teeth with height difference in the vertical direction, is very suitable for generating torsion plasma surface motion, and although the manufacturing process of a driver is increased to a certain extent by manufacturing the height difference of the movable and static comb teeth, the excellent motion characteristic still makes the vertical comb teeth driving become the choice of most of static driving micro scanning mirror driving structures.

The vertical comb drive has two main structures, one is a staggered vertical comb drive (SVC) and the other is a tilted vertical comb drive (Angular Vertical Comb-drive actuator, AVC).

AVC has better performance than SVC because in an electrostatic comb drive, the larger the overlap area between the fixed and movable combs, the stronger the electrostatic attraction force. However, in the current common AVC preparation method, polymer tension is generally utilized. Firstly, a plane comb tooth drive is processed on an SOI wafer by a deep etching process, and the movable comb tooth is provided with a hinge structure. Then processing polymer such as Benzocyclobutene (BCB) or negative adhesive on the hinge structure, heating again to make the polymer reflux, cooling, and using the tension of the polymer to make the movable comb teeth implement inclination so as to implement inclination angle vertical comb teeth driving. But this approach is disadvantageous for mass production and has poor reliability.

Therefore, how to improve the performance of the vertical comb structure and the process stability as much as possible, so as to improve the performance of the electrostatic MEMS micro-mirror is a technical problem to be solved at present.

Disclosure of Invention

In order to achieve the aim of improving the performance of the vertical comb tooth structure and improving the process stability as much as possible, the application provides a reverse angle vertical comb tooth micro mirror driving structure and a driving micro mirror manufactured by adopting a boss activating structure and a manufacturing method thereof.

In order to achieve the above purpose, the driving structure of the reverse angle vertical comb micromirror of the present invention comprises a main body and a cover plate covered on the main body; the cover plate comprises a cover plate substrate, and a dislocation activation boss and an inclination activation boss are fixed on the lower surface of the cover plate substrate; the height of the inclination angle activation boss is larger than that of the dislocation activation boss; the main body comprises a stator anchor, fixed comb teeth, movable comb teeth and a main body substrate, wherein the fixed comb teeth extend from the stator anchor, and the stator anchor is connected with the main body substrate through a snake-shaped beam; the movable comb teeth and the fixed comb teeth are mutually staggered; when the cover plate and the main body are assembled, the misplacement activation boss presses down the part connected with the fixed comb teeth, so that the vertical height difference between the fixed comb teeth and the movable comb teeth is generated; the stator anchor is pressed down by the inclination angle activating boss, so that the fixed comb teeth are tilted.

Further, a dislocation platform is connected between the snake-shaped beam and the stator anchor, and the stator anchor is connected with the dislocation platform through a fulcrum beam; when the cover plate and the main body are assembled, the dislocation platform is pressed down by the dislocation activating boss, so that vertical height difference between the fixed comb teeth and the movable comb teeth is generated.

Further, three dislocation activation bosses are fixed on the lower surface of the cover plate base; the three dislocation activation bosses are located above the dislocation platform, wherein two dislocation activation bosses are located above two ends of the dislocation platform, and the other dislocation activation platform is located at the bottom end of the dislocation platform.

Further, the cover plate is bonded to the body.

A driving micromirror comprising a mirror platform, electrodes and two oppositely disposed opposite vertical comb micromirror driving structures according to claim 1; two sides of the mirror surface platform are respectively connected with the main body substrate through two torsion beams; two ends of the mirror surface platform are respectively connected with a reverse angle vertical comb tooth micro mirror driving structure, the torsion beam is separated from the main body substrate through an isolation channel, and the electrodes are fixed above the main body substrate enclosed by the isolation channel.

Further, a positioning boss is fixed on the lower surface of the cover plate substrate, a positioning groove is formed in the main body substrate, and the positioning boss is inserted into the positioning groove.

Further, an optical reflection film layer may be disposed on the mirror platform.

The preparation method of the driving micro mirror comprises the following steps:

s1, preparing a micro-mirror main body and a micro-mirror cover plate;

the preparation of the micro mirror main body comprises the following steps:

SA1, removing an oxide layer on the surface of an SOI wafer;

SA2, etching an insulating channel groove on the front surface of the SOI wafer;

SA3, depositing oxide layers on two side walls of the insulating channel groove, and filling the insulating channel groove with polysilicon to obtain an insulating channel;

SA4, removing superfluous materials on the surface of the structure obtained in the step SA 3;

SA5, depositing a silicon dioxide insulating layer on the front surface of the structure obtained in the step SA4, and etching an electrode area;

SA6, depositing a metal layer on the front surface of the structure obtained in the step SA5, and etching the metal layer to obtain an electrode;

SA7, etching a snake-shaped beam, a dislocation platform, a fulcrum beam, a stator anchor, a fixed comb tooth, a movable comb tooth, a torsion beam, a mirror surface platform, a positioning groove and other device structures on the front surface of the structure obtained in the step SA 6;

SA8, etching a window on the back space of the structure obtained in the step G, etching the window from the back space to an oxygen-buried layer, and then etching the oxygen-buried layer to release the snake-shaped beam, the dislocation platform, the fulcrum beam, the stator anchor, the fixed comb teeth, the movable comb teeth, the torsion beam and the mirror surface platform;

the preparation of the micro-mirror cover plate comprises the following steps:

SB1, removing an oxide layer on the surface of a silicon wafer to obtain a cover plate substrate;

SB2, manufacturing a boss structure on the cover plate substrate, wherein the boss structure comprises a positioning boss, a dislocation activating boss and an inclination activating boss;

SB3, processing a through hole on the cover plate substrate;

s2, assembling the micro-mirror main body and the micro-mirror cover plate together, pressing down the stator anchor through the inclination angle activation boss, and tilting the fixed comb teeth by using the fulcrum beam as a rotating shaft; meanwhile, the dislocation platform is pressed down by the dislocation activating boss, the stator anchor generates vertical displacement, vertical height difference is further generated between the fixed comb teeth and the movable comb teeth, and the MEMS micro mirror with the reverse angle vertical comb tooth micro mirror driving structure is manufactured.

Further, step SB2 includes the steps of:

SB2.1, spin coating a photoresist layer on the front surface of the silicon wafer;

SB2.2, carrying out gray scale lithography on the photoresist to manufacture a boss structure.

Compared with the prior art, the invention has at least the following beneficial technical effects:

the reverse angle vertical comb micromirror driving structure is different from the conventional method that the movable comb teeth generate inclination angles, and the positions of the fixed comb teeth are changed, so that the process stability and the device operation stability are improved. The stator anchors with fixed comb teeth extending from the main body are pressed down by the inclined angle activation boss structure on the cover plate when the cover plate and the main body are assembled, and the fixed comb teeth are tilted by taking the fulcrum beam as a rotating shaft. Secondly, a dislocation platform connected with the stator anchor through a fulcrum beam is pressed down through a dislocation activating boss on the cover plate when the cover plate and the main body are assembled, the stator anchor generates vertical displacement, and vertical height difference is further generated between the fixed comb teeth and the movable comb teeth, so that a reverse angle vertical comb tooth micro mirror driving structure is obtained.

In the electrostatic comb-tooth driver, the larger the overlapping area between the fixed comb-tooth and the movable comb-tooth is, the stronger the electrostatic attraction force is. In the MEMS micro-mirror driven in the vertical comb structure, the micro-mirror reaches the maximum rotation angle when the overlapping angle of the fixed comb and the movable comb is the maximum. Under the condition that all parameters are basically consistent, when the maximum angle is reached, the overlapped area between the fixed comb teeth and the movable comb teeth of the AVC structure is larger than that of the SVC structure, and the advantages are more obvious when the angle is larger. The AVC structure has better performance than the SVC structure. However, AVC is usually processed by polymer tension, and its preparation method is unfavorable for mass processing and has poor reliability. Compared with the existing AVC preparation method, the reverse angle vertical comb micromirror driving structure manufactured by the boss activating structure is prepared by the standardized preparation method, so that the method is more beneficial to mass production and has higher reliability. The maximum rotation angle of the micromirror can be easily changed according to the selection of different heights of the activation bosses. Compared with the AVC structure, the fixed comb teeth and the movable comb teeth have larger overlapping area, can provide larger attractive force, and has more obvious advantages as the rotation angle of the micromirror is larger. In addition, the existing vertical comb tooth structure is often used for processing the movable comb teeth and the fixed comb teeth in different layers, and the gaps between the movable comb teeth and the fixed comb teeth are difficult to reduce and difficult to align. The comb teeth serving as the driving component in the structure can be simultaneously processed on the same layer, self-alignment is carried out, and the gap between the fixed comb teeth and the movable comb teeth can be smaller than the distance which can be achieved by the conventional process, so that more comb teeth are accommodated in the same area, and the electrostatic driving force of the structure is further improved.

Drawings

FIG. 1 is a schematic diagram of the prior art vertical comb structure;

FIG. 2 is a schematic diagram of a driving structure of a reverse angle vertical comb micromirror provided in the present application;

FIG. 3 is a schematic cross-sectional view of a reverse angle vertical comb micromirror driving structure provided in the present application;

FIG. 4 is an exploded schematic view of a reverse angle vertical comb micromirror driving structure provided in the present application;

FIG. 5 is a schematic diagram of a main body of a reverse angle vertical comb micromirror driving structure provided herein;

FIG. 6 is a schematic diagram of a cover plate of the reverse angle vertical comb micromirror driving structure provided in the present application;

FIG. 7 is a schematic diagram of a reverse angle vertical comb micromirror drive variation;

FIG. 8 is a schematic diagram of a micromirror body of an electrostatic MEMS micromirror provided herein;

FIG. 9 is a schematic diagram of a micromirror cover plate of an electrostatic MEMS micromirror provided herein;

FIG. 10 is a schematic cross-sectional view of an electrostatic MEMS micromirror provided herein;

FIG. 11 is a schematic diagram of an electrostatic MEMS micromirror provided herein;

FIG. 12 is a schematic diagram of a process for fabricating a bulk of an electrostatic MEMS micromirror according to the present application;

FIG. 13 is a schematic diagram of a fabrication process of a cover plate of an electrostatic MEMS micromirror provided in the present application;

FIG. 14 is a schematic diagram of an electrostatic MEMS micromirror assembly process for a main body and a cover plate;

reference numerals: 11. a cover substrate; 12. positioning the boss; 13. a dislocation activating boss; 14. inclination activating boss; 15. a through hole; 21. a main body substrate; 22. a snake beam; 23. a dislocation platform; 24. a fulcrum beam; 25. a stator anchor; 26. comb teeth are fixed; 27. moving comb teeth; 28. a positioning groove; 29. a mirror platform; 30. a torsion beam; 31. an insulating trench; 32. an electrode; 42. a new snake beam; 50. an insulating channel groove; 51. an oxide layer; 52. polycrystalline silicon; 53. a silicon dioxide insulating layer; 54. an electrode region; 55. etching a window in the back space; 56. an oxygen burying layer; 57. and (3) photoresist.

Detailed Description

In order to make the purpose and technical scheme of the invention clearer and easier to understand. The present invention will now be described in further detail with reference to the drawings and examples, which are given for the purpose of illustration only and are not intended to limit the invention thereto.

In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more. In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

Referring to fig. 1, fig. 1 is a schematic diagram of a conventional vertical comb structure. Under the condition that all parameters are basically consistent, when the maximum angle is reached, the overlapped area between the fixed comb teeth and the movable comb teeth of the AVC structure is larger than that of the SVC structure, and the advantages are more obvious when the angle is larger. The AVC structure has better performance than the SVC structure. Referring to fig. 2, fig. 2 is a schematic structural diagram of the present application, which is larger in overlapping area between the fixed comb teeth and the movable comb teeth compared with AVC structure, and can provide larger attractive force, and the larger the rotation angle of the micromirror is, the more obvious the advantage is.

Example 1

Referring to fig. 3 to 6, a reverse angle vertical comb micromirror driving structure fabricated using a boss activating structure is divided into a cover plate and a main body.

The cover plate includes a cover plate base 11, a positioning boss 12, a misalignment activation boss 13, and an inclination activation boss 14. The positioning boss 12, the dislocation activating boss 13 and the inclination activating boss 14 are fixedly connected to the lower surface of the cover plate base 11.

It will be appreciated that the pitch angle activation tabs 14 are of a greater height than the misalignment activation tabs 13 so that the stator anchors can be further depressed relative to the misalignment platform.

It should be understood that the verticality is only used for illustrating the displacement direction of the dislocation platform and the fixed comb teeth, and some deviation may be generated in actual production due to the manufacturing process or the manufacturing precision.

It will be appreciated that the misalignment activation projections 13 are intended to provide for stable control of the displacement of the misalignment platform and to enhance its stability after movement. The number of the dislocation activating bosses 13 can be one, two or more, if the number of the dislocation activating bosses 13 is three, the three dislocation activating bosses 13 are positioned above the U-shaped dislocation platform 23, wherein the two dislocation activating bosses 13 are positioned above two ends of the dislocation platform 23, and the center of the contact surface is closer to the two ends than the joint of the dislocation platform 23 and the fulcrum beam 24; the other dislocation activating platform 13 is located above the bottom center of the U-shaped dislocation platform. The purpose of the misalignment activation projections 13 is to provide vertical displacement for the stator anchors 25, and the specific shape and number of the misalignment activation projections 13 are not particularly limited by the present invention.

The main body comprises a main body base 21, a snake-shaped beam 22, a dislocation platform 23, a fulcrum beam 24, a stator anchor 25, fixed comb teeth 26, movable comb teeth 27 and positioning grooves 28.

Wherein, serpentine beam 22, dislocation platform 23, fulcrum beam 24, stator anchor 25, fixed broach 26 and movable broach 27 are processed at same layer, and it interconnect all is located the inside of main body substrate 21, and positioning groove 28 distributes around main body substrate 21.

The dislocation platform 23 is U-shaped, and two sides of the dislocation platform 23 are respectively connected with the main body substrate 21 through two snake-shaped beams 22; the stator anchors 25 are positioned on the inner side of the dislocation platform 23, and two sides of the stator anchors are respectively connected with the inner wall of the dislocation platform 23 through two fulcrum beams 24; one end of the stator anchor 25 is outwardly extended with a fixed comb tooth 26; the main body base 21 is extended with movable comb teeth 27, and the fixed comb teeth 26 and the movable comb teeth 27 are processed in the same layer and are mutually staggered.

The height of the inclination angle activating boss 14 is larger than that of the dislocation activating boss 13; the dislocation platform 23 is connected with the main body substrate 21 through the snake beam 22; the stator anchors 25 are connected with the dislocation platform 23 through fulcrum beams 24; the fixed comb teeth 26 extend from the stator anchors 25; the movable comb teeth 27 extend from the main body 21 to be staggered with the fixed comb teeth 26, and form a reverse angle vertical comb micromirror driving structure with the fixed comb teeth after the cover plate and the main body are assembled. The main body substrate 21 is provided with a positioning groove 28, and when the cover plate and the main body are assembled, the positioning boss 12 is inserted into the positioning groove 28 for positioning; the inclination angle activating boss 14 is positioned above the stator anchor 25, the inclination angle activating boss 14 presses down the stator anchor 25, and the fulcrum beam 24 is used as a rotating shaft, so that the fixed comb teeth 26 are tilted; the dislocation activating boss 13 is located above the dislocation platform 23, the dislocation platform 23 is pressed down by the dislocation activating boss 13, deformation of the snake-shaped beam 22 in the Z direction is caused, the stator anchor generates vertical displacement, and accordingly vertical height difference is generated between the fixed comb teeth 26 and the movable comb teeth 27, and finally the reverse-angle vertical comb tooth micro mirror driving structure is obtained. When the main body and the cover plate are assembled, the fixed comb teeth can move in the vertical direction while tilting, so that the reverse-angle vertical comb teeth micro-mirror driving structure is manufactured.

Alternatively, the movable and stationary combs 27, 26 may be generally rectangular or trapezoidal.

Alternatively, the dislocated platform 23 and the body base 21 may be connected by serpentine beams, or other beams that are stiffer in the X and Y directions and less stiff in the z direction, as the application is not limited in this regard.

Alternatively, the stator anchors 25 and the dislocated platform 23 may be connected by fulcrum beams 24, or other beams of lesser torsional stiffness, as the present application is not limited in this regard.

Optionally, the cover plate and the main body may be bonded or not, and in a specific embodiment, bonding is preferentially selected, so that displacement of the fixed comb teeth is more stable, and therefore performance stability of the micromirror is improved.

Example 2

Referring to fig. 7, fig. 7 is a variation of the above structure. The dislocation platform 23 and the fulcrum beam 24 are removed, the new snake beam 42 takes the functions of the original snake beam 22 and the fulcrum beam 24 into consideration, and compared with the original snake beam, the structure of the new snake beam prolongs the beam part of the tail end of the snake beam parallel to the x axis, so that the tail end of the snake beam is directly connected with the stator anchor 25, and the torsional rigidity is reduced; the stator anchors 25 are separated into two ends by a rotation axis defined by a beam portion of the ends of the new serpentine beam 42 parallel to the x-axis, the stator anchors 25 being located above the end closer to the moving comb teeth 27 as the lower offset activation bosses 13 and above the end farther from the moving comb teeth 27 as the higher tilt activation bosses 14. The variant structure can also achieve the purpose that the fixed comb teeth are tilted and have certain displacement downwards in the vertical direction, so the variant structure also belongs to the protection scope of the patent.

Example 3

An electrostatic MEMS micro-mirror according to embodiments of the present application is described below. The electrostatic MEMS micromirror comprises the above-described reverse angle vertical comb micromirror driving structure. It is also divided into two parts, including a main body and a cover plate covering the main body, wherein the main body additionally includes a mirror platform 29, torsion beams 30, isolation trenches 31 and electrodes 32. The two sides of the mirror surface platform 29 in the X direction are respectively connected with the main body substrate 21 through two torsion beams 30; two ends of the mirror surface platform 29 in the Y direction are respectively connected with a reverse angle vertical comb tooth micro mirror driving structure, and an isolation channel 31 is positioned at the periphery of the connection part of the torsion beam 30 and the main body substrate 21 and is used for realizing the electric isolation of the fixed comb teeth 26 and the movable comb teeth 27; an electrode 32 is fixed over the body substrate 21 enclosed by the isolation trench 31 for soldering the wire.

Referring to fig. 8, fig. 8 is a schematic diagram of a main body of an electrostatic MEMS micro-mirror provided in the present application. Wherein, four positioning grooves 28 are respectively distributed at four corners of the substrate; isolation channels 31 are located at the periphery of the torsion beam 30 where it joins the body base 21; an electrode 32 is fixed above the body substrate 21 enclosed by the isolation trench 31; the mirror platform 29 and the main body base 21 are connected by two torsion beams 30; two sides of the dislocation platform 23 are respectively connected with the main body substrate 21 through two snake-shaped beams 22; the stator anchors 25 are connected with the dislocation platform 23 through fulcrum beams 24; the fixed comb teeth 26 extend from the stator anchors 25; the movable comb teeth 27 extend from the mirror surface platform 29 and are perpendicular to the rotation axis determined by the torsion beam 30, and the fixed comb teeth 26 and the movable comb teeth 27 are processed in the same layer and are staggered with each other; the profile of the teeth is usually designed as a simple rectangle or trapezoid.

Optionally, the mirror platform 29 may be provided with an optical reflective film layer, and in a specific embodiment, the optical reflective film layer should be preferentially provided, which can greatly enhance the reflectivity of the mirror platform and improve the performance of the micromirror.

Alternatively, one end of the movable comb teeth 27 may be fixed to the mirror platform 29, may be fixed to the torsion beam 30, or may be fixed to a cantilever beam extending from the micromirror and parallel to the torsion beam, which is not particularly limited herein.

Alternatively, the shape of the micromirror is not limited in this application, for example: the micromirror surface may be circular, rectangular, elliptical, etc.

Optionally, the cover plate and the main body may be bonded or not, and in a specific embodiment, bonding is preferentially selected, so that displacement of the fixed comb teeth is more stable, and therefore performance stability of the micromirror is improved.

It should be appreciated that the movable comb teeth 27 are not necessarily perpendicular to the rotational axis defined by the torsion beam 30. For example, in the embodiment where the mirror surface is circular, the movable comb teeth may be dispersed circumferentially along the edge of the mirror surface, and the fixed comb teeth 26 are adjusted accordingly, which is not limited in this application.

It should be understood that the positioning groove 28 may or may not extend therethrough, and the angle between the inner wall and the z-axis may be set as desired, which is not limited in this application.

It should be understood that the positioning grooves 28 may be located at corners or edges, and the relative positions between the positioning grooves and the edges are only the same as the relative positions between the positioning bosses of the cover plate, which is not required in the present application.

Referring to fig. 9, fig. 9 is a schematic diagram of a cover plate of an electrostatic MEMS micro-mirror provided in the present application. The middle part of the micro mirror is provided with a through hole 15, so that a space is provided for the micro mirror to rotate around a rotation shaft determined by the torsion beam 30, and meanwhile, light rays are directly irradiated to the micro mirror and reflected are not blocked; the cover plate is fixedly provided with a positioning boss 12, a dislocation activating boss 13 and an inclination activating boss 14, and the relative positions of the positioning bosses 12 are the same as the relative positions of the positioning grooves 28 on the substrate of the main body and correspond to each other one by one; the relative position of the dislocation activating boss 13 on the cover plate is the same as the relative position of the dislocation platform 23 on the main body; the relative position of the tilt angle activation boss 14 on the cover plate is the same as the relative position of the stator anchor 25 on the body.

It should be understood that the angles between the outer walls of the dislocation activating boss 13 and the inclination activating boss 14 and the z-axis may be set according to actual needs, which is not limited in this application.

Referring to fig. 10 and 11, the main body and the cover plate are assembled together after the relative positions of the main body and the cover plate are determined through the positioning boss 12 and the positioning groove 28, wherein the inclination angle activating boss 14 is matched with the stator anchor 25, the inclination angle activating boss 14 presses down the stator anchor 25, and the supporting point beam 24 is used as a rotating shaft, so that the fixed comb teeth 26 are tilted; the dislocation activating boss 13 is matched with the dislocation platform 23, the dislocation platform 23 is pressed down by the dislocation activating boss 13, the snake-shaped beam 22 is deformed in the Z direction, the stator anchor generates vertical displacement, and accordingly vertical height difference is generated between the fixed comb teeth 26 and the movable comb teeth 27, and finally the reverse angle vertical comb tooth micro mirror driving structure is obtained.

It will be appreciated that the height of the tilt angle activation tab 14 is greater than the height of the misalignment activation tab 13. In a specific embodiment, the preferred height difference between the inclination angle activating boss 14 and the dislocation activating boss 13 is a height difference that can make the fixed comb teeth turn up and then point to the rotation axis determined by the torsion beam 30, so that the overlapping area between the fixed comb teeth 26 and the movable comb teeth 27 can be maximized, thereby achieving the best performance of the micromirror.

For purposes of this general description, height refers to the distance in the z-direction, which is perpendicular in this application.

It should be noted that the reverse angle vertical comb micromirror driving structure manufactured by the boss activated structure provided by the present application can be applied to not only electrostatic MEMS micromirrors but also any other MEMS devices.

Example 4

The preparation method of the electrostatic MEMS micro-mirror comprises the following steps:

the structure and principle of the driving micromirror are described in detail above, and since a new comb tooth structure is provided, a new manufacturing process is required to prepare the driving micromirror, and a related manufacturing process flow is briefly described with reference to fig. 12 to 14.

Referring to fig. 12, a method for manufacturing a micromirror main body includes the steps of:

(A) Treating the SOI wafer by adopting a diluted buffer hydrofluoric acid solution, and removing an oxide layer on the surface of the SOI wafer;

(B) Photoetching the front surface of the SOI wafer, and etching an insulating channel groove 50 by combining anisotropic inductively coupled plasma etching and isotropic dry etching;

(C) Depositing oxide layers 51 on two side walls of the insulation channel groove 50 by adopting a wet oxidation process, and filling the insulation channel groove 50 with polysilicon 52 by adopting a low-pressure chemical vapor deposition process to obtain an insulation channel 31;

(D) C, removing superfluous materials on the surface of the structure obtained in the step C by adopting a chemical mechanical polishing process;

(E) Depositing a silicon dioxide insulating layer 53 on the front surface of the structure obtained in the step D, and etching an electrode region 54 through photoetching and dry etching processes;

(F) Depositing a metal layer on the front surface of the structure obtained in the step E, and etching the metal layer through photoetching and dry etching processes to obtain an electrode 32;

(G) F, photoetching the front surface of the structure obtained in the step F, and etching the structures of various devices such as a snake-shaped beam 22, a dislocation platform 23, a fulcrum beam 24, a stator anchor 25, a fixed comb tooth 26, a movable comb tooth 27, a torsion beam 30, a mirror surface platform 29, a positioning groove 28 and the like by adopting an anisotropic inductively coupled plasma etching process;

(H) Depositing a silicon dioxide layer on the back of the structure obtained in the step G, and etching a back space etching window 55 through photoetching and dry etching processes;

(I) The anisotropic inductively coupled plasma etching process is used to etch the buried oxide layer 55 from the back space etching window 54, and then the dry etching process is used to etch the buried oxide layer 56, releasing the serpentine beam 22, the dislocating platform 23, the fulcrum beam 24, the stator anchors 25, the fixed comb teeth 26, the movable comb teeth 27, the torsion beam 30 and the mirror platform 29.

Referring to fig. 13, the method for preparing the micromirror cover plate comprises the following steps:

(J) Treating the silicon wafer with diluted buffer hydrofluoric acid solution to remove the surface oxide layer to obtain a cover plate substrate 11;

(K) Spin-coating a layer of photoresist 57 on the front surface of the cover substrate 11, wherein the photoresist 57 is SU-8 photoresist;

(L) carrying out gray scale lithography on the photoresist 57 to manufacture boss structures with different heights; the boss structure comprises a positioning boss 12, a dislocation activating boss 13 and an inclination activating boss 14;

(M) laser machining is used to manufacture the through-hole 15.

The method directly uses the photoresist as the boss structure, and compared with the conventional process, the method reduces the subsequent etching process and reduces the processing cost.

Referring to fig. 14, the driving micromirror manufacturing method includes the steps of:

(M) after aligning the cover plate and the main body, assembling by a bonding process, pressing down a stator anchor 25 extending out of the fixed comb teeth 26 on the main body by using an inclination angle activating boss 13 on the cover plate, and tilting the fixed comb teeth 26 by using a fulcrum beam 24 as a rotating shaft. Secondly, the dislocation platform 23 connected with the stator anchor 25 through the fulcrum beam 24 is pressed down by the dislocation activating boss 14 on the cover plate when the cover plate and the main body are assembled, the stator anchor 25 generates vertical displacement, and vertical height difference is further generated between the fixed comb teeth 26 and the movable comb teeth 27, so that the MEMS micro mirror with a reverse angle vertical comb tooth micro mirror driving structure is manufactured.

The reverse angle vertical comb micromirror driving structure and the electrostatic MEMS micromirror manufactured by the boss activating structure are described in detail above. Specific examples are set forth herein to illustrate the principles and embodiments of the present application, and the description of the above examples is merely intended to aid in understanding the methods and concepts of the present application, and are directed to, for example: the terms upper, lower, left, right, front or rear, etc. are used for illustration only and are not intended to limit the present application. It should be noted that it would be obvious to those skilled in the art that various improvements and modifications can be made to the present application without departing from the principles of the present application, and such improvements and modifications fall within the scope of the claims of the present application.

Note that the above is only a preferred embodiment of the present application. Those skilled in the art will appreciate that the present application is not limited to the specific embodiments described herein, and that various obvious changes, rearrangements, combinations, and substitutions can be made by those skilled in the art without departing from the scope of the present application. Therefore, while the present application has been described in connection with the above embodiments, the present application is not limited to the above embodiments, but may include many other equivalent embodiments without departing from the spirit of the present application, the scope of which is defined by the scope of the appended claims.

Claims (9)

1. The reverse angle vertical comb micromirror driving structure is characterized by comprising a main body and a cover plate covered on the main body; the cover plate comprises a cover plate substrate (11), wherein a dislocation activation boss (13) and an inclination activation boss (14) are fixed on the lower surface of the cover plate substrate (11); the height of the inclination angle activating boss (14) is larger than that of the dislocation activating boss (13);

the main body comprises a stator anchor (25), fixed comb teeth (26), movable comb teeth (27) and a main body substrate (21), wherein the fixed comb teeth (26) extend from the stator anchor (25), and the stator anchor (25) is connected with the main body substrate (21) through a snake-shaped beam (42); the movable comb teeth (27) and the fixed comb teeth (26) are mutually staggered;

when the cover plate and the main body are assembled, the misplacement activation boss (13) presses down a part connected with the fixed comb teeth (26), so that the vertical height difference is generated between the fixed comb teeth (26) and the movable comb teeth (27); the stator anchor (25) is pressed down by the inclination angle activating boss (14) to enable the fixed comb teeth (26) to tilt.

2. The reverse-angle vertical comb micromirror driving structure according to claim 1, wherein a dislocation platform (23) is connected between the serpentine beam (42) and the stator anchor (25), and the stator anchor (25) is connected to the dislocation platform (23) through a fulcrum beam (24); when the cover plate and the main body are assembled, the dislocation platform (23) is pressed down by the dislocation activating boss (13), so that vertical height difference between the fixed comb teeth (26) and the movable comb teeth (27) is generated.

3. The driving structure of the reverse-angle vertical comb micromirror and the driving micromirror thereof according to claim 2, wherein three dislocation activating bosses (13) are fixed on the lower surface of the cover substrate (11); three dislocation activation bosses (13) are located above the dislocation platform (23), wherein two dislocation activation bosses (13) are located above two ends of the dislocation platform (23), and the other dislocation activation platform (13) is located at the bottom end of the dislocation platform (23).

4. The reverse angle vertical comb micromirror driving structure according to claim 1, wherein the cover plate is bonded to the main body.

5. A driving micromirror, characterized by comprising a mirror platform (29), electrodes (32) and two oppositely disposed opposite-angle vertical comb micromirror driving structures according to claim 1;

two sides of the mirror surface platform (29) are respectively connected with the main body substrate (21) through two torsion beams (30); the two ends of the mirror surface platform (29) are respectively connected with a reverse angle vertical comb tooth micro mirror driving structure, the torsion beam (30) is separated from the main body substrate (21) through the isolation channel (31), and the electrode (32) is fixed above the main body substrate (21) enclosed by the isolation channel (31).

6. The driving micromirror according to claim 5, wherein a positioning boss (12) is fixed on the lower surface of the cover substrate (11), a positioning groove (28) is formed on the main substrate, and the positioning boss (12) is inserted into the positioning groove (28).

7. A driving micromirror according to claim 5, wherein the mirror platform (29) is provided with an optically reflective film layer.

8. A method of producing a driving micromirror as defined in claim 5, comprising the steps of:

s1, preparing a micro-mirror main body and a micro-mirror cover plate;

the preparation of the micro mirror main body comprises the following steps:

SA1, removing an oxide layer on the surface of an SOI wafer;

SA2, etching an insulating channel groove (50) on the front surface of the SOI wafer;

SA3, depositing oxide layers (51) on two side walls of the insulating channel groove (50), and filling the insulating channel groove (50) with polysilicon (52) to obtain an insulating channel (31);

SA4, removing superfluous materials on the surface of the structure obtained in the step SA 3;

SA5, depositing a silicon dioxide insulating layer (53) on the front surface of the structure obtained in the step SA4, and etching an electrode region (54);

SA6, depositing a metal layer on the front surface of the structure obtained in the step SA5, and etching the metal layer to obtain an electrode (32);

SA7, etching a snake-shaped beam (22), a dislocation platform (23), a fulcrum beam (24), a stator anchor (25), fixed comb teeth (26), movable comb teeth (27), torsion beams (30), a mirror surface platform (29), a positioning groove (28) and other device structures on the front surface of the structure obtained in the step SA 6;

SA8, etching a window (55) in the back space of the structure obtained in the step G, etching the window (55) to an oxygen burying layer (56), and then etching the oxygen burying layer (56), releasing the snake beam (22), the dislocation platform (23), the fulcrum beam (24), the stator anchor (25), the fixed comb teeth (26), the movable comb teeth (27), the torsion beam (30) and the mirror surface platform (29);

the preparation of the micro-mirror cover plate comprises the following steps:

SB1, removing an oxide layer on the surface of a silicon wafer to obtain a cover plate substrate (11);

SB2, manufacturing a boss structure on a cover plate substrate (11), wherein the boss structure comprises a positioning boss (12), a dislocation activating boss (13) and an inclination activating boss (14);

SB3, processing a through hole (15) on the cover plate substrate (11);

s2, assembling the micro-mirror main body and the micro-mirror cover plate together, pressing down the stator anchor (25) through the inclination angle activation boss (13), and tilting the fixed comb teeth (26) by taking the fulcrum beam (24) as a rotating shaft; meanwhile, the dislocation platform (23) is pressed down by the dislocation activating boss (14), the stator anchor (25) generates vertical displacement, so that vertical height difference is further generated between the fixed comb teeth (26) and the movable comb teeth (27), and the MEMS micro mirror with the reverse angle vertical comb tooth micro mirror driving structure is manufactured.

9. The method of manufacturing a driving micromirror according to claim 8, wherein the step SB2 comprises the steps of:

SB2.1, spin coating a photoresist layer on the front surface of the silicon wafer;

SB2.2, carrying out gray scale lithography on the photoresist to manufacture a boss structure.

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