MEMS mirror, MEMS mirror array, and radar system

Abstract

Embodiments of the present disclosure provide an MEMS mirror, an MEMS mirror array, and a radar system. The MEMS mirror comprises: an outer frame, wherein the outer frame is of a hollow structure; a rotating structure, wherein the rotating structure is located in a hollow area of the outer frame, the rotating structure comprises a reflecting mirror frame and a pair of rotating shafts connected between the reflecting mirror frame and the outer frame, and the reflecting mirror frame comprises a grounding electrode; a reflecting mirror, located on the reflecting mirror frame; a base, wherein the base and the outer frame form a cavity; and a steering electrode group, located on the side of the base facing the rotating structure, wherein the steering electrode group comprises a first steering electrode and a second steering electrode which are arranged on two sides of the pair of rotating shafts. When the grounding electrode and the base are parallel, the distance between the first steering electrode and the grounding electrode is gradually reduced from the outer side of the reflecting mirror to the inner side, and the distance between the second steering electrode and the grounding electrode is gradually reduced from the outer side of the reflecting mirror to the inner side.

Description

MEMS galvanometer, MEMS galvanometer array and radar system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on July 27, 2023, with application number 202310928124.5 and invention name "A MEMS galvanometer, MEMS galvanometer array and radar system", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present disclosure relates to the technical field of micro-electromechanical systems, and in particular to a MEMS galvanometer, a MEMS galvanometer array, and a radar system. Background Art

[0004] A MEMS (Miciro-Electro-Mechanical System) galvanometer is a tiny, drivable mirror made based on MEMS technology, and its mirror diameter is usually only a few millimeters. Compared with traditional optical scanning mirrors, MEMS galvanometers have the advantages of light weight, small size, easy mass production, and low production cost. They perform more outstandingly in terms of optical, mechanical properties, and power consumption. MEMS galvanometers are currently maturely used in markets such as lidar, high-definition projection, laser confocal microscopy, and AR. The movement modes of MEMS galvanometers include two mechanical movements: translation and torsion. For torsional MEMS galvanometers, when the optical deflection angle is large (reaching 10° or more), laser pointing deflection, graphical scanning, and image scanning can be achieved.

[0005] Summary of the Invention

[0006] The embodiments of the present disclosure provide a MEMS galvanometer, a MEMS galvanometer array, and a radar system. The specific solutions are as follows:

[0007] An embodiment of the present disclosure provides a MEMS galvanometer, comprising:

[0008] An outer frame, wherein the outer frame is a hollow structure;

[0009] a rotating structure, the rotating structure being located in the hollow area of ​​the outer frame, the rotating structure comprising a reflector frame and a pair of rotating shafts connected between the reflector frame and the outer frame, the reflector frame comprising a ground electrode;

[0010] a reflector, located on the reflector frame;

[0011] a base, wherein the base and the outer frame form a cavity;

[0012] A steering electrode group is located on the side of the substrate facing the rotating structure, and the steering electrode group includes a first steering electrode and a second steering electrode arranged on both sides of the pair of rotating shafts; wherein,

[0013] When the ground electrode and the substrate are parallel, the distance between the first steering electrode and the ground electrode gradually decreases from the outside to the inside of the reflector, and the distance between the second steering electrode and the ground electrode gradually decreases from the outside to the inside of the reflector.

[0014] In a possible implementation, in the above-mentioned MEMS oscillator provided in an embodiment of the present disclosure, the surface of the substrate facing the reflector is a flat surface, and the first steering electrode and the second steering electrode both include at least two step structures whose thickness gradually increases from the outside to the inside of the reflector, and each of the step structures serves as a sub-electrode.

[0015] In a possible implementation, in the above-mentioned MEMS oscillating mirror provided in an embodiment of the present disclosure, the substrate has at least two step structures at positions corresponding to the first steering electrode and the second steering electrode, the thickness of which gradually increases from the outside to the inside of the reflector, and the first steering electrode and the second steering electrode are arranged on the corresponding step structures.

[0016] In one possible implementation, in the above-mentioned MEMS galvanometer provided in an embodiment of the present disclosure, a first angle is formed between the inclined surface formed by each steering electrode and the substrate, and a second angle is formed between the reflector frame and the substrate after being twisted at the maximum angle, and the degree of the first angle is smaller than the degree of the second angle.

[0017] In a possible implementation, in the above-mentioned MEMS oscillating mirror provided in an embodiment of the present disclosure, the ground electrode faces the surface of the substrate and the corresponding positions of the first steering electrode and the second steering electrode have at least two step structures whose thickness gradually increases from the outside to the inside of the reflector.

[0018] In a possible implementation, in the MEMS galvanometer provided in an embodiment of the present disclosure, the first steering electrode and the second steering electrode each include sub-electrodes arranged corresponding to the stepped structure, and the sub-electrodes have the same thickness.

[0019] In a possible implementation, in the MEMS galvanometer provided in the embodiment of the present disclosure, there is a gap between every two adjacent sub-electrodes in the first steering electrode and the second steering electrode.

[0020] In a possible implementation, the MEMS galvanometer provided in the embodiment of the present disclosure further includes a first isolation layer arranged on the side of the steering electrode group facing the ground electrode, and the orthographic projection of the first isolation layer on the substrate covers the substrate and fills the gap.

[0021] In a possible implementation, in the above-mentioned MEMS galvanometer provided in an embodiment of the present disclosure, the width of each of the step structures corresponding to the first steering electrode gradually increases from the outside to the inside of the reflector, and the width of each of the step structures corresponding to the second steering electrode gradually increases from the outside to the inside of the reflector.

[0022] In a possible implementation, in the above-mentioned MEMS galvanometer provided in an embodiment of the present disclosure, the outer frame and the rotating structure are an integrated structure formed by using a silicon substrate, and the reflector frame is reused as the ground electrode.

[0023] In a possible implementation, in the above-mentioned MEMS oscillating mirror provided in an embodiment of the present disclosure, the pair of rotating axes are located on the same straight line and coincide with the central axis of the reflector, and the first steering electrode and the second steering electrode are symmetrically distributed on both sides of the central axis of the reflector.

[0024] In a possible implementation, in the above-mentioned MEMS oscillating mirror provided in an embodiment of the present disclosure, the shape of the reflector is the same as the shape of the reflector frame, and the size of the reflector is the same as the size of the reflector frame.

[0025] In a possible implementation, in the above-mentioned MEMS oscillating mirror provided in an embodiment of the present disclosure, the shape of the reflector includes a circle or an ellipse, and the rotating shaft is connected to the outer annular surface of the reflector frame.

[0026] In a possible implementation, in the above-mentioned MEMS vibrating mirror provided in an embodiment of the present disclosure, the shape of the reflector is square, a pair of side edges of the reflector frame have a concave structure, and the rotating shaft is embedded in the concave structure and connected to the reflector frame.

[0027] In a possible implementation, the MEMS galvanometer provided in the embodiment of the present disclosure further includes: a plurality of contact electrodes disposed between the steering electrode group and the substrate and corresponding to the stepped structures in a one-to-one manner; a first driving structure disposed between the contact electrodes and the substrate and corresponding to the first steering electrodes; and a second driving structure disposed between the contact electrodes and the substrate and corresponding to the second steering electrodes; wherein,

[0028] The first steering electrode is electrically connected to the corresponding contact electrode, and the second steering electrode is electrically connected to the corresponding contact electrode;

[0029] The contact electrodes corresponding to the first steering electrodes are electrically connected to the first driving structure, and the contact electrodes corresponding to the second steering electrodes are electrically connected to the second driving structure.

[0030] In a possible implementation, in the MEMS galvanometer provided in an embodiment of the present disclosure, the first driving structure includes: a first driving electrode electrically connected to each of the contact electrodes corresponding to the first steering electrode, and a first driving line electrically connected to the first driving electrode;

[0031] The second driving structure includes: second driving electrodes electrically connected to the contact electrodes corresponding to the second steering electrodes, and second driving lines electrically connected to the second driving electrodes.

[0032] In a possible implementation, in the MEMS galvanometer provided in an embodiment of the present disclosure, the first driving structure includes: first driving electrodes electrically connected one-to-one to the contact electrodes corresponding to the first steering electrodes, and first driving lines electrically connected one-to-one to the first driving electrodes;

[0033] The second driving structure includes: second driving electrodes electrically connected to the contact electrodes corresponding to the second steering electrodes in a one-to-one correspondence, and second driving lines electrically connected to the second driving electrodes in a one-to-one correspondence.

[0034] In a possible implementation, the above-mentioned MEMS galvanometer provided in an embodiment of the present disclosure further includes: a second isolation layer arranged between the contact electrode and the first drive structure, the second drive structure, and a third isolation layer arranged between the contact electrode and the steering electrode group; wherein the second isolation layer exposes the first drive electrode and the second drive electrode, and the third isolation layer exposes the contact electrode.

[0035] Correspondingly, an embodiment of the present disclosure further provides a MEMS galvanometer array, comprising a plurality of the above-mentioned MEMS galvanometers provided by an embodiment of the present disclosure arranged in an array.

[0036] In a possible implementation, in the above-mentioned MEMS galvanometer array provided in an embodiment of the present disclosure, the first steering electrode in each of the MEMS galvanometers corresponds to one or a plurality of first drive lines that are the same number as the step structure, and the second steering electrode in each of the MEMS galvanometers corresponds to one or a plurality of second drive lines that are the same number as the step structure, and each of the first drive lines in each of the MEMS galvanometers is electrically connected to the same first drive voltage terminal, and each of the second drive lines in each of the MEMS galvanometers is electrically connected to the same second drive voltage terminal.

[0037] In a possible implementation, in the above-mentioned MEMS galvanometer array provided in an embodiment of the present disclosure, the first steering electrode in each of the MEMS galvanometers corresponds to a plurality of first drive lines having the same number as the step structure, and the second steering electrode in each of the MEMS galvanometers corresponds to a plurality of second drive lines having the same number as the step structure; wherein,

[0038] The first driving lines corresponding to the stepped structures at the same position in the MEMS galvanometers are electrically connected to the same first driving voltage terminal, and the first driving lines corresponding to the stepped structures at different positions in the MEMS galvanometers are electrically connected to different first driving voltage terminals;

[0039] The second drive lines corresponding to the stepped structures at the same position in each MEMS galvanometer are electrically connected to the same second drive voltage terminal, and the second drive lines corresponding to the stepped structures at different positions in each MEMS galvanometer are electrically connected to different second drive voltage terminals.

[0040] Correspondingly, an embodiment of the present disclosure further provides a radar system, comprising the above-mentioned MEMS galvanometer according to an embodiment of the present disclosure, or comprising the above-mentioned MEMS galvanometer array according to an embodiment of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic diagram of the corresponding transmitting and receiving system when a conventional MEMS galvanometer array is applied to a laser radar;

[0042] FIG2 is a schematic structural diagram of a MEMS galvanometer provided in an embodiment of the present disclosure;

[0043] FIG3 is a plan view corresponding to FIG2 ;

[0044] FIG4 is an exploded schematic diagram of the structure of each layer corresponding to FIG2 ;

[0045] FIG5 is a schematic cross-sectional view of a portion of the structure along the AA′ direction in FIG3 ;

[0046] FIG6 is a schematic diagram showing the deflection effect of the MEMS galvanometer when an AC voltage is applied to the first steering electrode shown in FIG5 ;

[0047] FIG7 is a schematic diagram showing the deflection effect of the MEMS galvanometer when an AC voltage is applied to the second steering electrode shown in FIG5 ;

[0048] FIG8 is a diagram showing a partial circuit connection structure in FIG4 ;

[0049] FIG9 is a diagram showing a partial circuit connection structure in FIG4 ;

[0050] 10A-10F are schematic structural diagrams of a manufacturing process flow of the MEMS galvanometer shown in FIG. 2 according to an embodiment of the present disclosure;

[0051] FIG11 is a schematic structural diagram of another MEMS galvanometer provided in an embodiment of the present disclosure;

[0052] FIG12 is a plan view corresponding to FIG11;

[0053] FIG13 is an exploded schematic diagram of the structure of each layer corresponding to FIG11;

[0054] FIG14 is a schematic cross-sectional view of a portion of the structure along the AA′ direction in FIG12 ;

[0055] FIG15 is a schematic diagram showing the deflection effect of the MEMS galvanometer when an AC voltage is applied to the first steering electrode in FIG14;

[0056] FIG16 is a schematic diagram showing the deflection effect of the MEMS galvanometer when an AC voltage is applied to the second steering electrode in FIG14;

[0057] FIG17 is a schematic structural diagram of another MEMS galvanometer provided in an embodiment of the present disclosure;

[0058] FIG18 is a plan view corresponding to FIG17;

[0059] FIG19 is an exploded schematic diagram of the structure of each layer corresponding to FIG17;

[0060] FIG20 is a schematic cross-sectional view of a portion of the structure along the AA′ direction in FIG18 ;

[0061] FIG21 is a schematic cross-sectional view of a portion of the structure along the AA′ direction after the first isolation layer is provided in FIG13 ;

[0062] 22A-22B are schematic diagrams of a process flow for manufacturing the MEMS galvanometer shown in FIG. 17 ;

[0063] FIG23 is a schematic structural diagram of another MEMS galvanometer provided in an embodiment of the present disclosure;

[0064] FIG24 is a plan view corresponding to FIG23;

[0065] FIG25 is an exploded schematic diagram of the structure of each layer corresponding to FIG23;

[0066] FIG26 is a diagram showing a partial circuit connection structure in FIG25;

[0067] FIG27 is a diagram showing a partial circuit connection structure in FIG25;

[0068] 28A-28G are schematic diagrams of a manufacturing process flow of the MEMS galvanometer shown in FIG. 23 ;

[0069] FIG29 is an exploded schematic diagram of the structure of each layer of another MEMS galvanometer provided by an embodiment of the present disclosure;

[0070] FIG30 is a diagram showing a partial circuit connection structure in FIG29;

[0071] FIG31 is a diagram showing a partial circuit connection structure in FIG29;

[0072] FIG32 is a schematic cross-sectional view of a portion of the structure in FIG29;

[0073] FIG33 is a schematic structural diagram of another MEMS galvanometer provided in an embodiment of the present disclosure;

[0074] FIG34 is a schematic structural diagram of another MEMS galvanometer provided in an embodiment of the present disclosure;

[0075] FIG35 is a schematic diagram of a MEMS galvanometer array structure provided by an embodiment of the present disclosure;

[0076] FIG36 is a schematic diagram of a corresponding transmitting and receiving system when the MEMS galvanometer array provided by an embodiment of the present disclosure is applied to a laser radar;

[0077] 37A-37D are schematic diagrams of the manufacturing process flow of the MEMS galvanometer array shown in FIG. 35 . DETAILED DESCRIPTION

[0078] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. And in the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0079] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words “include” or “comprise” and the like used in this disclosure mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The words “connect” or “connected” and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Inside”, “outside”, “upper”, “lower”, etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0080] It should be noted that the sizes and shapes of the figures in the accompanying drawings do not reflect the actual scale and are only for the purpose of illustrating the present disclosure. The same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions.

[0081] The mirror diameter of a MEMS galvanometer is usually only a few millimeters. It is a tiny, drivable mirror made based on MEMS technology. Compared with traditional optical scanning mirrors, it has superior performance such as small size, low power consumption, and high integration. It is currently mainly used in fields such as LiDAR. As shown in Figure 1, Figure 1 is a schematic diagram of the corresponding transmitting and receiving system when a conventional MEMS galvanometer array is applied to LiDAR. The laser emitted by the laser transmitting component is reflected by ordinary mirrors and MEMS galvanometers in turn to nearby objects (obstacles), and is fed back to the control component according to the process shown in Figure 1. The small angle twisting of the MEMS galvanometer can enable the laser beam to scan the surface, and the image signal of the surrounding environment is obtained by processing the changes in the beam information fed back. Compared with traditional optical scanning mirrors, MEMS galvanometers obtained through micromachining technology have the advantages of light weight, small size, easy mass production, and low production cost, and are gradually replacing traditional optical scanning mirrors in fields such as LiDAR.

[0082] Currently, MEMS galvanometers driven by flat electrodes are widely used. While their structure is simple and their processing is easy, the electrostatic force between the flat electrodes creates an adsorption effect that requires a high drive voltage and is prone to pull-in. While the electrostatic force can be increased by reducing the distance between the flat electrodes, this also limits the usable angular range of the MEMS galvanometer.

[0083] The present disclosure provides a MEMS galvanometer, as shown in FIG2 to FIG5 , FIG2 is a structural schematic diagram of the MEMS galvanometer, FIG3 is a plan schematic diagram corresponding to FIG2 , FIG4 is an exploded schematic diagram of each layer structure corresponding to FIG2 , and FIG5 is a cross-sectional schematic diagram of a portion of the structure along the AA′ direction in FIG3 , wherein the MEMS galvanometer includes:

[0084] The outer frame 1 is a hollow structure; specifically, the outer frame 1 mainly plays a supporting role;

[0085] The rotating structure 2 is located in the hollow area of ​​the outer frame 1. The rotating structure 2 can use the hollow area of ​​the outer frame 1 to deflect, thereby achieving deflection of the light beam; the rotating structure 2 includes a reflector frame 21 and a pair of rotating shafts 22 connected between the reflector frame 21 and the outer frame 1, that is, one end of the rotating shaft 22 is fixed to the outer frame 1, and the other end of the rotating shaft 22 is fixed to the reflector frame 21; the reflector frame 21 includes a ground electrode GND;

[0086] The reflector 3 is located on the reflector frame 21. Specifically, the reflector 3 deflects in the same manner as the reflector frame 21 deflects. The reflector 3 can reflect the laser beam emitted by the laser emitting assembly and project it into the corresponding scanning area.

[0087] A base 4, wherein the base 4 and the outer frame 1 form a cavity;

[0088] The steering electrode group 5 is located on the side of the base 4 facing the rotating structure 2. The steering electrode group 5 includes a first steering electrode 51 and a second steering electrode 52 arranged on both sides of a pair of rotating shafts 22. Specifically, a ground voltage is applied to the ground electrode GND, and an AC voltage (driving voltage) is applied to the first steering electrode 51 or the second steering electrode 52. The electrostatic adsorption force generated between the ground electrode GND and the first steering electrode 51 or the ground electrode GND and the second steering electrode 52 drives the reflector frame 21 and the reflector 3 to deflect in a preset direction around the rotating shaft 22.

[0089] When the ground electrode GND is parallel to the substrate 1 , the distance between the first steering electrode 51 and the ground electrode GND gradually decreases from the outside to the inside of the reflector 3 , and the distance between the second steering electrode 52 and the ground electrode GND gradually decreases from the outside to the inside of the reflector 3 .

[0090] In the MEMS galvanometer provided in the embodiments of the present disclosure, when the ground electrode and the substrate are parallel, the distance between the first steering electrode and the ground electrode is set to gradually decrease from the outside to the inside of the reflector, and the distance between the second steering electrode and the ground electrode is set to gradually decrease from the outside to the inside of the reflector. That is, the distance between the first steering electrode and the ground electrode and the distance between the second steering electrode and the ground electrode are set to change in a step-like manner. Since the smaller the distance between the first steering electrode, the second steering electrode and the ground electrode, the greater the capacitance, the greater the electrostatic adsorption force between the first steering electrode, the second steering electrode and the ground electrode. In this way, the electrostatic adsorption force can be increased by reducing the spacing between the steering electrode group and the ground electrode without reducing the maximum torsion angle of the reflector. In this way, under the condition of the same electrostatic adsorption force, the present disclosure can reduce the driving voltage and reduce power consumption. In addition, when the ground electrode is deflected, the step-by-step change in distance creates a larger gap between the ground electrode and the first steering electrode or the second steering electrode, which helps to reduce the adhesion between the ground electrode and the first steering electrode or the second steering electrode, thereby reducing the probability of the attraction phenomenon.

[0091] Optionally, the reflector 3 may be made of metal material, or other materials capable of forming reflection.

[0092] In a specific implementation, in the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 2 to 4, the outer frame 1 and the rotating structure 2 can be an integral structure formed by using a silicon substrate. Since the silicon substrate is a semiconductor, the reflector frame 21 of the rotating structure 2 can be directly reused as the ground electrode GND. Specifically, the galvanometer based on the MEMS process provided in the embodiment of the present disclosure can form an outer frame 1 for fixing the rotating structure 2 in an integral manner while forming the rotating structure 2, so that the outer frame 1 is used to fix the rotating structure 2 to the other main structures of the MEMS galvanometer, which can increase the stability of the fixation and reduce the wear on the reflector 3 caused by the fixing process, thereby effectively improving the service life of the reflector 3.

[0093] Optionally, the silicon substrate may be made of single crystal silicon or polycrystalline silicon.

[0094] In specific implementations, the present disclosure can form the rotating structure 2 located in the hollow area of ​​the outer frame 1 by etching the silicon substrate, and the reflector 3 can be formed on the reflector frame 21 by deposition or sputtering. The above preparation processes are all relatively mature operating steps in the MEMS process and will not be described in detail in the embodiments of the present disclosure.

[0095] Specifically, as shown in FIG. 2 to FIG. 5 , the base 4 also adopts a silicon substrate, but is certainly not limited thereto.

[0096] In a specific implementation, in the above-mentioned MEMS galvanometer provided by the embodiment of the present disclosure, as shown in Figures 2, 4, and 5, the surface of the substrate 4 facing the reflector 3 is a flat surface, and the first steering electrode 51 and the second steering electrode 51 each include at least two stepped structures with thickness gradually increasing from the outside to the inside of the reflector 3, each stepped structure serving as a sub-electrode. Compared to the completely flat steering electrode structure in the conventional structure, the embodiment of the present disclosure improves the steering electrode group into a stepped structure with thickness gradually increasing from both sides to the middle. This ensures that while the spacing between the first steering electrode 51 and the ground electrode GND and between the second steering electrode 51 and the ground electrode GND is reduced, the maximum torsion angle of the reflector 3 does not decrease, thereby increasing the electrostatic adsorption force between the electrodes. In this way, under the condition of the same electrostatic adsorption force, the present disclosure can reduce the driving voltage and power consumption.

[0097] Specifically, the electric field magnitudes formed between the first steering electrode 51 and the ground electrode GND and between the second steering electrode 51 and the ground electrode GND when voltage is applied are calculated as follows: The calculation formula for the electrostatic adsorption force between the first steering electrode 51 and the ground electrode GND and between the second steering electrode 51 and the ground electrode GND is: Among them, E is the electric field, C is the capacitance, V is the voltage, ε is the dielectric constant, d is the distance between the stepped structure and the ground electrode, F is the electrostatic adsorption force, and S is the facing area between the ground electrode and the steering electrode; according to the above-mentioned electrostatic adsorption force calculation formula, it can be seen that when V is constant, the magnitude of the electrostatic adsorption force is inversely proportional to d, so the electrostatic strength can be enhanced by reducing d, and S is equivalent to the size of the projected overlapping area of ​​the ground electrode and the steering electrode, which has nothing to do with the surface undulation of the steering electrode. Therefore, the overall appearance of the steering electrode group is designed to be a stepped structure with a certain inclination angle. Without affecting the maximum torsion angle of the reflector, the distance between the first steering electrode 51 and the ground electrode GND and the distance between the second steering electrode 51 and the ground electrode GND can be significantly reduced, thereby reducing the driving voltage and reducing power consumption.

[0098] It should be noted that, in the embodiment of the present disclosure, the first steering electrode 51 and the second steering electrode 51 each include three step structures as an example. Of course, they can also include two step structures respectively, or four or more step structures respectively. As long as the step structures gradually increase in thickness from both sides of the reflector 3 to the middle, they fall within the scope of protection of the embodiment of the present disclosure. The number of step structures in each steering electrode is designed according to actual needs.

[0099] In a specific implementation, in the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 6 and 7, Figure 6 is a schematic diagram of the deflection effect of driving the MEMS galvanometer when an AC voltage is applied to the first steering electrode 51, and Figure 7 is a schematic diagram of the deflection effect of driving the MEMS galvanometer when an AC voltage is applied to the second steering electrode 52. A first angle θ1 is formed between the inclined surface L1 formed by the first steering electrode 51 and the substrate 4, and a first angle θ1 is formed between the inclined surface L2 formed by the second steering electrode 52 and the substrate 4. After the reflector frame 21 is twisted to the maximum angle, a second angle θ2 is formed between the reflector frame 21 and the substrate 4. The degree of the first angle θ1 is less than the degree of the second angle θ2. In this way, it is ensured that while the spacing between the first steering electrode 51 and the ground electrode GND and between the second steering electrode 51 and the ground electrode GND is reduced, the maximum torsion angle of the reflector 3 will not be reduced. Therefore, the present disclosure does not limit the available angle range of the MEMS galvanometer, and thus does not limit the beam scanning range.

[0100] In a specific implementation, in the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in FIG6 , there is a gap between each two adjacent sub-electrodes (stepped structures) in the first steering electrode 51 and the second steering electrode 52, that is, the sub-electrodes in the first steering electrode 51 are spaced apart, and the sub-electrodes in the second steering electrode 52 are spaced apart. In this way, when the reflector frame 21 deflects toward the steering electrode side, since there is a gap between each two adjacent step structures, and ideally only the vertical edge of the step structure is in contact with the ground electrode GND, the setting of the gap is beneficial to reducing the adhesion between the steering electrode and the ground electrode, thereby reducing the probability of the attraction phenomenon.

[0101] Optionally, as shown in FIG6 , the gap width between step structures of different heights may be 6 μm to 10 μm, for example, the gap width may be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0102] In a specific implementation, in the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 2 to 4, a pair of rotating shafts 22 are located on the same straight line and coincide with the central axis of the reflector 3, and the first steering electrode 51 and the second steering electrode 52 are symmetrically distributed on both sides of the central axis of the reflector 3. Specifically, the farther the sub-electrodes (stepped structure) in the steering electrode are from the central axis, the smaller the required driving voltage, and vice versa. When the size of the ground electrode GND is fixed (i.e., the size of the reflector frame 21 is fixed), when designing the stepped structure, it is necessary to ensure that the distance between the sub-electrodes and the central axis is not too large, which would result in a reduction in the electrode equivalent area.

[0103] In a specific implementation, in the above-mentioned MEMS galvanometer provided in the embodiments of the present disclosure, as shown in Figures 2 to 4 , the shape of the reflector 3 is the same as the shape of the reflector frame 21, and the size of the reflector 3 is the same as the size of the reflector frame 21. It should be noted that the size of the reflector 3 and the size of the reflector frame 21 being the same means being approximately the same, and there may be certain errors in actual production. For example, the size of the reflector 3 may be slightly smaller than the size of the reflector frame 21.

[0104] In a specific implementation, in the MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 2 to 4 , the shape of the reflector 3 can be circular, and the rotating shaft 22 is connected to the outer annular surface of the reflector frame 21. Alternatively, the shape of the reflector 3 can also be elliptical.

[0105] In a specific implementation, in the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 4 to 9, Figure 8 is a diagram of a partial circuit connection structure in Figure 4, and Figure 9 is a diagram of a partial circuit connection structure in Figure 4. The MEMS galvanometer further includes: a plurality of contact electrodes 6 arranged between the steering electrode group 5 and the substrate 4 and corresponding to the step structures, a first driving structure 7 arranged between the contact electrode 6 and the substrate 4 and corresponding to the first steering electrode 51, and a second driving structure 7 arranged between the contact electrode 6 and the substrate 4 and corresponding to the second steering electrode 52; wherein,

[0106] The first steering electrode 51 is electrically connected to the corresponding contact electrode 6 , and the second steering electrode 52 is electrically connected to the corresponding contact electrode 6 ;

[0107] The contact electrodes 6 corresponding to the first steering electrode 51 are electrically connected to the first drive structure 7, and the contact electrodes 6 corresponding to the second steering electrode 52 are electrically connected to the second drive structure 8. Specifically, the bottom of the first steering electrode 51 is interconnected with the first drive structure 7 through the contact electrode 6, and the bottom of the second steering electrode 52 is interconnected with the second drive structure 8 through the contact electrode 6. Since the gap between adjacent step structures is very small, according to the edge effect of the electric field, the first steering electrode 51 and the second steering electrode 52 can be equivalent to a complete electrode without a gap. During operation, the first drive structure 7 applies a driving voltage to the first steering electrode 51 through the contact electrode 6, and the second drive structure 8 applies a driving voltage to the second steering electrode 52 through the contact electrode 6, respectively forming an electric field with the ground electrode GND to generate an electrostatic adsorption force, so that the reflector 3 is deflected in a preset direction, and the reflector 3 can reflect the laser beam emitted by the laser emitting component and project it into the corresponding scanning area.

[0108] In a specific implementation, in the MEMS galvanometer provided in the embodiment of the present disclosure, as shown in FIG4 to FIG9 , the first driving structure 7 includes: a first driving electrode 71 electrically connected to each contact electrode 6 corresponding to the first steering electrode 51 , and a first driving line 72 electrically connected to the first driving electrode 71 ;

[0109] The second driving structure 8 includes: a second driving electrode 81 electrically connected to each contact electrode 6 corresponding to the second steering electrode 52, and a second driving line 82 electrically connected to the second driving electrode 81. Specifically, in this embodiment, the contact electrodes 6 corresponding to the stepped structures of different thicknesses in the first steering electrode 51 are arranged to be electrically connected to the same first driving electrode 71, and the contact electrodes 6 corresponding to the stepped structures of different thicknesses in the second steering electrode 52 are arranged to be electrically connected to the same second driving electrode 72. That is, one driving structure connects all the stepped structures in the corresponding steering electrodes. In this way, a driving voltage is applied to all the stepped structures in the first steering electrode 51 via the first driving line 72, and a driving voltage is applied to all the stepped structures in the second steering electrode 52 via the second driving line 82, which can reduce the complexity of the driving structure design.

[0110] In a specific implementation, in order to avoid a short circuit between the contact electrode and the first drive structure, the second drive structure, and between the contact electrode and the steering electrode group, the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 4-8, also includes: a second isolation layer 9 arranged between the contact electrode 6 and the first drive structure 7, the second drive structure 8, and a third isolation layer 10 arranged between the contact electrode 6 and the steering electrode group 5; wherein the second isolation layer 9 exposes the first drive electrode 71 and the second drive electrode 81, so as to realize electrical connection between the first drive electrode 71 and the second drive electrode 81 and the corresponding contact electrode 6 respectively; the third isolation layer 10 exposes the contact electrode 6, so as to realize corresponding electrical connection between the contact electrode 6 and the first steering electrode 51 and the second steering electrode 52.

[0111] Optionally, the materials of the second isolation layer 9 and the third isolation layer 10 include but are not limited to insulating materials such as SiNx.

[0112] The following describes the manufacturing process of the MEMS galvanometer shown in FIG. 2 provided by the embodiment of the present disclosure. The specific manufacturing process steps are as follows:

[0113] 1. A metal film layer (eg, a Cu layer) is sputtered and deposited on a substrate 4 (silicon substrate), and the metal film layer is patterned and etched to form a first driving structure 7 and a second driving structure 8, as shown in FIG10A .

[0114] 2. A SiNx film layer is deposited on the first driving structure 7 and the second driving structure 8 by PECVD, and the SiNx film layer is patterned by ICP etching technology to expose the first driving electrode 71 and the second driving electrode 81 to form a second isolation layer 9, as shown in FIG10B .

[0115] 3. Sputter-deposit a Cu layer on the second isolation layer 9 again, and pattern-etch the Cu layer to form a plurality of contact electrodes 6 corresponding to the first drive electrodes 71 and the second drive electrodes 81 , as shown in FIG10C .

[0116] 4. A SiNx film layer is deposited again on the contact electrode 6 by PECVD, and the surface is flattened and the contact electrode 6 is exposed by chemical mechanical polishing (CMP) technology to form a third isolation layer 10, as shown in FIG10D.

[0117] 5. Sputter-deposit a Cu layer on the third isolation layer 10, spin-coat photoresist, and use a photoresist process to pattern-etch the Cu layer to form a conductive structure corresponding to the contact electrode 6. Repeat the steps of depositing the Cu layer, spin-coating the photoresist, and patterning the Cu layer to form a stepped first steering electrode 51 and second steering electrode 52 with a certain height difference, as shown in Figure 10E.

[0118] 6. Etch the outer frame 1 and the rotating structure 2 on another silicon substrate using ICP etching technology. The reflector frame 21 of the rotating structure 2 is reused as the ground electrode GND. Bond the substrate 4 and the outer frame 1 together, as shown in FIG10F .

[0119] 7. Spin-coat photoresist (sacrificial layer) to fill the hollow area of ​​FIG. 10F , then coat the surface of the reflector frame 21 with reflective material to form the reflector 3 , and after removing the sacrificial layer, obtain the MEMS oscillating mirror shown in FIG. 2 provided in the embodiment of the present disclosure.

[0120] In summary, the MEMS galvanometer shown in FIG. 2 provided by the embodiment of the present disclosure has at least the following advantages:

[0121] 1. The MEMS galvanometer structure designed in the present disclosure is not complicated in design and can be manufactured using existing semiconductor device manufacturing technology. The overall manufacturing process is relatively simple.

[0122] 2. By replacing the conventional flat electrode structure with a stepped steering electrode, the distance between the steering electrode and the ground electrode can be reduced without reducing the maximum torsion angle of the galvanometer, thereby reducing the driving voltage and power consumption.

[0123] 3. When the reflector frame deflects toward the steering electrode, there is a gap between each two adjacent step structures, and ideally only the vertical edge of the step structure contacts the ground electrode. Therefore, the setting of the gap is beneficial to reduce the adhesion between the steering electrode and the ground electrode, thereby reducing the probability of attraction.

[0124] In a specific implementation, in the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 11 to 16, Figure 11 is another structural schematic diagram of the MEMS galvanometer, Figure 12 is a planar schematic diagram corresponding to Figure 11, Figure 13 is an exploded schematic diagram of each layer structure corresponding to Figure 11, Figure 14 is a cross-sectional schematic diagram of part of the structure along the AA' direction in Figure 12, Figure 15 is a schematic diagram of the deflection effect of driving the MEMS galvanometer when the first steering electrode 51 is loaded with an AC voltage, and Figure 16 is a schematic diagram of the deflection effect of driving the MEMS galvanometer when the second steering electrode 52 is loaded with an AC voltage. The width of each step structure corresponding to the first steering electrode 51 gradually increases from the outside to the inside of the reflector 3, and the width of each step structure corresponding to the second steering electrode 52 gradually increases from the outside to the inside of the reflector 3. Specifically, the MEMS galvanometer shown in FIG13 of the embodiment of the present disclosure has no significant overall structural changes compared to the MEMS galvanometer shown in FIG4 . The only change is the width of the stepped structures of different thicknesses in the stepped steering electrode. The design of the stepped structures being designed with equal widths in FIG4 is changed to a design where the width gradually increases from the outside to the inside of the reflector 3. The structural changes in FIG13 and FIG4 can be seen from the schematic diagrams of FIG14-FIG16 and FIG5-FIG7 . The maximum torsion angle of the MEMS galvanometer remains unchanged, and the height difference, gap, overall width, and position between the stepped structures of the stepped steering electrode remain unchanged. Only the stepped structures of different heights gradually widen from the outside to the inside of the reflector 3.

[0125] Specifically, as shown in Figures 11 to 14, when the reflector 3 is not twisted, the stepped structure with the smallest distance from the ground electrode GND is mainly driven. When the reflector 3 is twisted by a certain angle, the stepped structure with the largest distance from the ground electrode GND is mainly driven. Therefore, compared with the conventional MEMS galvanometer, the improvement of the step structure width gradient of the MEMS galvanometer shown in Figures 11 to 14 in this embodiment can make the area of ​​the stepped structure of the initial drive (when the reflector is not twisted) larger, and can provide a greater electrostatic adsorption force under the same driving voltage. When the reflector 3 is twisted by the electrostatic adsorption force, although the area of ​​the stepped structure with the largest distance from the ground electrode is reduced, the twisted reflector 3 can compensate for the reduced electrostatic adsorption force through inertia.

[0126] Specifically, the other film layer structures and manufacturing processes in Figures 11 to 14 refer to the aforementioned description of the structures shown in Figures 2 to 5. The only difference in the manufacturing process is that the width gradient change is made when manufacturing the steering electrode group, which will not be repeated here.

[0127] In a specific implementation, when the MEMS galvanometer shown in Figures 4 and 13 is working, during the deflection of the ground electrode GND toward the steering electrode, when the torsion angle is maximum, a short circuit may occur between the ground electrode GND and the steering electrode. This may cause a sudden strong current to break down the MEMS galvanometer, thereby damaging the MEMS galvanometer. Therefore, in the above-mentioned MEMS galvanometer provided in the embodiment of the present disclosure, as shown in Figures 17 to 20, Figure 17 is another structural schematic diagram of the MEMS galvanometer, Figure 18 is a planar schematic diagram corresponding to Figure 17, Figure 19 is an exploded schematic diagram of each layer structure corresponding to Figure 17, and Figure 20 is a cross-sectional schematic diagram of a portion of the structure along the AA' direction in Figure 18. The MEMS galvanometer also includes a first isolation layer 11 provided on the side of the steering electrode group 5 facing the ground electrode GND. The orthographic projection of the first isolation layer 11 on the substrate 4 covers the substrate 4 and fills the gap. In this way, the first isolation layer 11 is added to cover the surface of the steering electrode group during the process preparation as an isolation layer to protect the ground electrode GND and the steering electrode from short circuit problems when they come into contact.

[0128] Optionally, the material of the first isolation layer 11 includes but is not limited to insulating materials such as SiNx.

[0129] It should be noted that, during the SiNx deposition process, SiNx is filled in the gaps between the stepped structures with different depths. Since the gap width is less than 10 μm, it will not affect the edge effect of the steering electrode.

[0130] It should be noted that Figures 17 to 20 are based on Figures 2 to 5, and a first isolation layer 11 is set on the side of the steering electrode group 5 facing the ground electrode GND; of course, the first isolation layer 11 can also be set on the side of the steering electrode group 5 facing the ground electrode GND based on Figures 11 to 14, as shown in Figure 21, which is a cross-sectional schematic diagram of the partial structure along the AA' direction after the first isolation layer 11 is set in Figure 13.

[0131] Specifically, the other film layer structures in Figures 17 to 21 refer to the aforementioned description of the structures shown in Figures 2 to 5, and will not be repeated here.

[0132] Specifically, the fabrication process for the MEMS galvanometer shown in Figure 17 differs from that of the MEMS galvanometer shown in Figure 2 in that, after the stepped first and second steering electrodes 51, 52 are formed in step 5, a material such as SiNx can be deposited via a PECVD process as a first isolation layer 11, covering the first and second steering electrodes 51, 52, as shown in Figure 22A. Subsequently, the fabrication process follows steps 6 and 7, as described in Figure 2. The corresponding structure after step 6 is shown in Figure 22B, and the corresponding structure after step 7 is shown in Figure 17. Thus, Figures 10A-10E, 22A, 22B, and 17 are process flow diagrams for fabricating the MEMS galvanometer shown in Figure 17.

[0133] In a specific implementation, when the MEMS galvanometer provided by the embodiment of the present disclosure is applied to a laser radar, in order to increase the scanning area of ​​the laser radar, in the above-mentioned MEMS galvanometer provided by the embodiment of the present disclosure, as shown in Figures 23 to 27, Figure 23 is another structural schematic diagram of the MEMS galvanometer, Figure 24 is a planar schematic diagram corresponding to Figure 23, Figure 25 is an exploded schematic diagram of the structure of each layer corresponding to Figure 23, Figure 26 is a partial circuit connection structure diagram in Figure 25, and Figure 27 is a partial circuit connection structure diagram in Figure 25. The shape of the reflector 3 can be square, and a pair of side edges of the reflector frame 21 have a concave structure, and the rotating shaft 22 is embedded in the concave structure and connected to the reflector frame 21. Based on Figure 17, this embodiment changes the reflector 3 of the MEMS galvanometer from the original circular shape to a square shape, that is, the reflector frame 21 is changed from the original circular shape to a square shape, so that the cavity space of the outer frame 1 can be used to the maximum extent, thereby increasing the scanning range of the galvanometer. At the same time, the increase in the size of the reflector frame 21 means that the effective area of ​​the ground electrode GND and the steering electrode increases. Therefore, the steering electrode is correspondingly lengthened on both sides, thereby increasing its effective area. According to the aforementioned electrostatic adsorption force calculation formula, a greater electrostatic adsorption force is obtained at the same driving voltage.

[0134] Specifically, the other film layer structures in Figures 23 to 27 refer to the aforementioned description of the structures shown in Figures 2 to 5. The only difference is that the shape of the reflector 3 and the reflector frame 21 is changed to a square, and the length of the steering electrode is correspondingly increased, which will not be repeated here.

[0135] Specifically, the manufacturing process flow for the MEMS galvanometer shown in FIG23 can be referred to the process flow for manufacturing FIG2 , with the following differences: a first isolation layer is deposited to cover the steering electrode group after the steering electrode group is formed, and when the outer frame 1 and rotating structure 2 are formed, the reflector frame 21 is formed into a square shape with a pair of side edges having concave structures, and the rotating shaft 22 is embedded in the concave structures and connected to the reflector frame 21. The manufacturing process flow diagram for the MEMS galvanometer shown in FIG23 is shown in FIG28A-FIG28G and FIG23 .

[0136] It should be noted that the connection positions of the first driving line 72 and the second driving line 82 in Figures 25 to 27 and the first driving line 72 and the second driving line 82 in Figures 4, 8 and 9 are different from those of the step structure in the steering electrode, but their functions are the same.

[0137] In a specific implementation, in the above-mentioned MEMS galvanometer provided in an embodiment of the present disclosure, as shown in FIG29 to FIG32 , FIG29 is an exploded schematic diagram of each layer structure of the MEMS galvanometer, FIG30 is a partial circuit connection structure diagram in FIG29 , FIG31 is a partial circuit connection structure diagram in FIG29 , and FIG32 is a cross-sectional schematic diagram of a portion of the structure in FIG29 , the first driving structure 7 includes: first driving electrodes 71 electrically connected to each contact electrode 6 corresponding to the first steering electrode 51 in a one-to-one correspondence, and first driving lines 72 electrically connected to each first driving electrode 71 in a one-to-one correspondence;

[0138] The second driving structure 8 includes second driving electrodes 81 electrically connected to the contact electrodes 6 corresponding to the second steering electrodes 52 in a one-to-one correspondence, and second driving lines 82 electrically connected to the second driving electrodes 81 in a one-to-one correspondence. In this embodiment, the first drive electrodes 71 below the stepped structures of different thicknesses are changed from the original one-to-many pattern (one first drive electrode 71 is connected to all corresponding stepped structures via the contact electrode 6) to a one-to-one pattern (one first drive electrode 71 is connected to a corresponding stepped structure via the contact electrode 6), and each first drive electrode 71 is electrically connected to a different first drive line 72. The second drive electrodes 81 below the stepped structures of different thicknesses are changed from the original one-to-many pattern (one first drive electrode 71 is connected to all corresponding stepped structures via the contact electrode 6) to a one-to-one pattern (one second drive electrode 81 is connected to a corresponding stepped structure via the contact electrode 6), and each second drive electrode 81 is electrically connected to a different second drive line 82. The drive structure routing distribution is shown in Figures 30 and 31. Taking the example of each steering electrode including three stepped structures, each steering electrode is divided into three steps of different thicknesses and connected to the underlying drive electrode via the contact electrode 6. Other structural designs can still adopt the solutions of any of the embodiments described in Figures 2 to 28G above. The specific structure is shown in Figure 29. The MEMS galvanometer shown in FIG. 29 provided by the present disclosure adopts a multi-channel driving structure to connect step structures of different thicknesses one-to-one, and can realize different power supply modes for the steering electrodes by powering with digital control signals.

[0139] Specifically, compared to the single-channel control steering electrodes shown in Figures 8 and 9, Figures 30 and 31 use digital signals to control the steering electrodes in multiple channels. Not only can they be powered on simultaneously to achieve the same effect as Figures 8 and 9, but they can also determine the on and off of different step structures based on the torsion angle of the reflector. For example, when the reflector is not twisted, the thickest step structure with a smaller distance from the ground electrode is mainly driven. When the reflector is twisted to a certain angle, the thinnest step structure with a larger distance from the ground electrode is mainly driven, achieving various forms of free control. In addition, separately controlling the stepped steering electrodes can also reduce power consumption.

[0140] Specifically, the other film layer structures in Figures 29 to 32 refer to the above description of the structures shown in Figures 2 to 5. The only difference is that the connection method between the first driving structure 7, the second driving structure 8 and the contact electrode 6 is changed, which will not be repeated here.

[0141] It should be noted that the MEMS galvanometers shown in the aforementioned Figures 2 to 32 are all equipped with stepped steering electrodes to reduce the distance between the ground electrode and the steering electrode, and some other improvements are made on the basis of the stepped steering electrodes. Of course, in the specific implementation, in order to reduce the distance between the ground electrode and the steering electrode, there can also be other designs. For example, as shown in Figure 33, Figure 33 is a structural schematic diagram of another MEMS galvanometer provided by the embodiment of the present disclosure. The substrate 4 has at least two stepped structures with gradually increasing thickness from the outside to the inside of the reflector 3 at the corresponding positions of the first steering electrode 51 and the second steering electrode 52. The first steering electrode 51 and the second steering electrode 52 are arranged on the corresponding stepped structures. Specifically, the first steering electrode 51 and the second steering electrode 52 each include sub-electrodes arranged corresponding to the stepped structures, and the thickness of each sub-electrode is the same. This can also achieve the same effect as the aforementioned Figures 2 to 32, and by designing a separately driven driving structure, multi-channel control of the steering electrodes can be achieved, thereby reducing power consumption. According to the calculation formula for the magnitude of the electrostatic adsorption force: It can be seen that the magnitude of the electrostatic adsorption force is independent of the thickness of the steering electrode. Therefore, in this embodiment, a stepped substrate 4 is designed to replace the steering electrodes of different thicknesses in the previous embodiment, and then a layer of Cu metal is deposited on the substrate 4 and patterned to form a steering electrode. Similarly, a steering electrode with a different distance from the ground electrode GND can be formed.

[0142] In a specific implementation, the first steering electrode 51 in FIG33 may be an integral structure, and the second steering electrode 52 may be an integral structure, so that single-channel control of the steering electrode can be achieved and the complexity of the drive structure design can be reduced.

[0143] In a specific implementation, to produce the MEMS galvanometer shown in FIG33 , a base 4 with a stepped gradient height can be first formed on a silicon substrate by multiple etchings, and then a layer of Cu metal is deposited to pattern a driving structure and a steering electrode with a certain gap. The process steps of the outer frame 1 and the rotating structure 2 are the same as those in the above embodiment. Finally, they are combined into a MEMS galvanometer through bonding, and a reflector is formed on the reflector frame.

[0144] Specifically, the other membrane layer structures in the MEMS oscillating mirror corresponding to FIG33 refer to the aforementioned description of the structures shown in FIG2-FIG32 , and the main difference lies in the different structures of the substrate 1 and the steering electrode, which will not be elaborated here.

[0145] In specific implementation, in order to reduce the distance between the ground electrode and the steering electrode, other designs can also be used. For example, as shown in Figure 34, Figure 34 is a structural schematic diagram of another MEMS galvanometer provided in an embodiment of the present disclosure. The ground electrode GND faces the surface of the substrate 1 and the corresponding positions of the first steering electrode 51 and the second steering electrode 52 have at least two step structures with gradually increasing thickness from the outside to the inside of the reflector 3. In this embodiment, the steering electrode adopts a traditional flat structure, and the ground electrode GND is designed to be a stepped structure with a gradually decreasing distance from the outside to the inside with the steering electrode. This can also achieve the same effect as the aforementioned Figures 2 to 32. In terms of specific process steps, a traditional flat steering electrode structure is prepared on the substrate, and the stepped ground electrode GND required in Figure 34 is formed by multiple ICP etching techniques. Finally, a complete MEMS galvanometer is made through process steps such as bonding, preparing the reflector, and releasing the sacrificial layer.

[0146] In a traditional flat-panel mirror frame structure, the larger the size of the MEMS galvanometer mirror, the greater the moment of inertia of the mirror, which in turn reduces the resonant frequency. However, the MEMS galvanometer mirror structure design shown in FIG34 of the present disclosure shifts the mass distribution of the mirror frame from both sides toward the axis of rotation, reducing the moment of inertia required for torsion on both sides of the mirror frame, thereby increasing the resonant frequency of the MEMS galvanometer mirror.

[0147] In a specific implementation, in the MEMS galvanometer provided in the embodiment of the present disclosure, as shown in FIG34 , the first steering electrode 51 and the second steering electrode 52 can be a monolithic structure. Of course, the first steering electrode 51 and the second steering electrode 52 can also each include sub-electrodes corresponding to the stepped structures of the ground electrode GND, with each sub-electrode having the same thickness. This allows for single-channel control of the steering electrode or multiple-channel control of the steering electrode, allowing for control according to actual needs.

[0148] Specifically, the other membrane layer structures in the MEMS galvanometer corresponding to FIG34 refer to the aforementioned description of the structures shown in FIG2-FIG34 , and the main difference lies in the different structures of the ground electrode GND and the steering electrode, which will not be elaborated here.

[0149] In specific implementations, in the MEMS galvanometer provided in the embodiments of the present disclosure, as shown in Figures 33 and 34 , a gap is provided between each adjacent sub-electrode in the first steering electrode 51 and the second steering electrode 52. The provision of the gap helps reduce adhesion between the steering electrode and the ground electrode, thereby reducing the probability of pull-in. Optionally, the gap width can be 6 μm to 10 μm, for example, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0150] In addition, the MEMS galvanometer provided by the embodiments of the present disclosure also has the following advantages:

[0151] 1. The MEMS galvanometer provided in the embodiment of the present disclosure is an actively tunable one-dimensional MEMS galvanometer, which drives the rotation of the MEMS galvanometer through the electrostatic adsorption force generated between the ground electrode GND and the first steering electrode 51 or the second steering electrode 52. It has the characteristics of simple structure, small size and mature technology of traditional electrostatically driven MEMS galvanometer.

[0152] 2. The MEMS galvanometer provided in the embodiment of the present disclosure is merely a simple improvement on the basis of a conventional MEMS galvanometer, and its implementation process is simple and the cost fluctuation is small.

[0153] Based on the same inventive concept, the embodiments of the present disclosure also provide a MEMS galvanometer array, as shown in FIG35 , comprising a plurality of MEMS galvanometers as described above in the embodiments of the present disclosure arranged in an array. Specifically, the MEMS galvanometer array shown in FIG35 has the beneficial effects of the aforementioned MEMS galvanometers, and when the MEMS galvanometers provided in the embodiments of the present disclosure are applied to a laser radar, the MEMS galvanometer array can reflect external laser beams, thereby enabling the laser radar to obtain a larger scanning range.

[0154] As shown in Figure 36, Figure 36 is a schematic diagram of the corresponding transmitting and receiving system when the MEMS galvanometer array provided by the embodiment of the present disclosure is applied to a laser radar. In a laser radar system composed of traditional optical reflectors, it is necessary to achieve a larger torsion angle of the reflector to achieve a wider range of scanning. However, the present disclosure adopts a multi-group MEMS galvanometer array arrangement. The maximum torsion angle of each MEMS galvanometer unit 100 does not change, but the MEMS galvanometer array can also achieve a wider range of scanning. Moreover, the volume change of the MEMS galvanometer realized by micromachining technology is small, and the integration is high.

[0155] As shown in FIG35 , in the embodiment of the present disclosure, the stepped MEMS galvanometer units 100 are periodically arranged to obtain a MEMS galvanometer array. The example given in this embodiment is a 4×4 array arrangement. In actual application, it is not limited to this arrangement form, and different arrangement designs can be made according to actual needs.

[0156] In a specific implementation, in the above-mentioned MEMS galvanometer array provided in the embodiment of the present disclosure, as shown in FIG35 , when the MEMS galvanometer adopts the circuit structure shown in FIG8 , the first steering electrode 51 in each MEMS galvanometer corresponds to a first drive line 72, and the second steering electrode 52 in each MEMS galvanometer corresponds to a second drive line 82. Each first drive line 72 in each MEMS galvanometer is electrically connected to the same first drive voltage terminal (-), and each second drive line 82 in each MEMS galvanometer is electrically connected to the same second drive voltage terminal (+). Specifically, the first drive voltage terminal (-) is a negative AC voltage, and the second drive voltage terminal (+) is a positive AC voltage. The AC voltage is loaded on the first drive voltage terminal (-) or the second drive voltage terminal (+) according to the preset deflection direction of the reflector 3. As shown in FIG35 , the MEMS galvanometer array further includes a plurality of first traces 20 and a plurality of second traces 30 extending in the row direction and alternately arranged in the column direction, and a first trace 20 and a second trace 30 are correspondingly arranged on both sides of each row of galvanometer units 100 in the row direction; the MEMS galvanometer array further includes a plurality of galvanometer units 100 arranged in the row direction. The third and fourth lines 40 and 50 on the periphery; in the embodiment of the present disclosure, the first driving lines 72 corresponding to each row of the multiple galvanometer units 100 arranged in an array are electrically connected to the corresponding first lines 20, and then all the first lines 20 are electrically connected to the third lines 40, and the third lines 40 are electrically connected to the first driving voltage terminal (-); all the second driving lines 82 corresponding to the multiple galvanometer units 100 arranged in an array are electrically connected to the corresponding second lines 30, and then all the second lines 30 are electrically connected to the fourth lines 50, and the fourth lines 50 are electrically connected to the second driving voltage terminal (+). In this way, all the first steering electrodes 51 in the present disclosure are driven simultaneously by the same first driving voltage terminal (-), and all the second steering electrodes 52 are driven simultaneously by the same second driving voltage terminal (+), so that a larger scanning range can be obtained.

[0157] In a specific implementation, in the above-mentioned MEMS galvanometer array provided in the embodiment of the present disclosure, as shown in FIG35 , when the MEMS galvanometer adopts the circuit structure shown in FIG30 , the first steering electrode 51 in each MEMS galvanometer corresponds to a plurality of first drive lines 72 having the same number as the step structure, and the second steering electrode 52 in each MEMS galvanometer corresponds to a plurality of second drive lines 82 having the same number as the step structure, and each first drive line 72 in each MEMS galvanometer is electrically connected to the same first drive voltage terminal (-), and each second drive line 82 in each MEMS galvanometer is electrically connected to the same second drive voltage terminal (+). In this way, all first steering electrodes 51 can be driven simultaneously by the same first drive voltage terminal (-), and all second steering electrodes 52 can be driven simultaneously by the same second drive voltage terminal (+), thereby obtaining a larger scanning range.

[0158] The manufacturing process of the MEMS galvanometer array shown in FIG35 is shown in FIG37A to FIG37D . The basic process flow is the same as the MEMS galvanometer manufacturing process shown in FIG2 , specifically:

[0159] 1. A first driving structure 7 and a second driving structure 8, as well as a first trace 20, a second trace 30, a third trace 40, a fourth trace 50, a first driving voltage terminal (-) and a second driving voltage terminal (+) are fabricated on a substrate 1 in an array distribution, as shown in FIG37A.

[0160] 2. Based on Figure 37A, the second isolation layer 9, contact electrode 6, and third isolation layer 10 in the manufacturing process of the MEMS galvanometer shown in Figure 2 are manufactured in sequence. The third isolation layer 10 exposes the contact electrode 6, the first driving voltage terminal (-) and the second driving voltage terminal (+), as shown in Figure 37B.

[0161] 3. The first steering electrode 51 and the second steering electrode 52 in the manufacturing process of the MEMS galvanometer shown in FIG2 are manufactured based on FIG37B , as shown in FIG37C .

[0162] Afterwards, the outer frame 1 and the rotating structure 2 in the manufacturing process of the MEMS galvanometer shown in Figure 2 are manufactured, the substrate 4 and the outer frame 1 are bonded together, the sacrificial layer is filled in the hollow area, the reflector 3 is formed, and the sacrificial layer is removed, and the MEMS galvanometer array shown in Figure 35 can be obtained, as shown in Figure 37D.

[0163] In a specific implementation, in the above-mentioned MEMS galvanometer array provided in an embodiment of the present disclosure, when the MEMS galvanometer adopts the circuit structure shown in FIG30 , the first steering electrode 51 in each MEMS galvanometer corresponds to a plurality of first drive lines 72 having the same number as the staircase structure, and the second steering electrode 52 in each MEMS galvanometer corresponds to a plurality of second drive lines 82 having the same number as the staircase structure; wherein,

[0164] The first drive lines corresponding to the stepped structures at the same position in each MEMS galvanometer are all electrically connected to the same first drive voltage terminal. For example, the first drive lines 72 corresponding to the stepped structures with the smallest thickness in each MEMS galvanometer are all electrically connected to the same first drive voltage terminal (-), the first drive lines 72 corresponding to the stepped structures with the middle thickness in each MEMS galvanometer are all electrically connected to the same first drive voltage terminal (-), and the first drive lines 72 corresponding to the stepped structures with the largest thickness in each MEMS galvanometer are all electrically connected to the same first drive voltage terminal (-); the first drive lines corresponding to the stepped structures at different positions in each MEMS galvanometer are all electrically connected to different first drive voltage terminals. For example, the first drive lines 72 corresponding to the stepped structures with different thicknesses in each MEMS galvanometer are all electrically connected to different first drive voltage terminals (-);

[0165] The second driving lines corresponding to the stepped structures located at the same position in each MEMS galvanometer are all electrically connected to the same second driving voltage terminal. For example, the second driving lines 82 corresponding to the stepped structures with the smallest thickness in each MEMS galvanometer are all electrically connected to the same second driving voltage terminal (+), the second driving lines 82 corresponding to the stepped structures with the middle thickness in each MEMS galvanometer are all electrically connected to the same second driving voltage terminal (+), and the second driving lines 82 corresponding to the stepped structures with the largest thickness in each MEMS galvanometer are all electrically connected to the same second driving voltage terminal (+); the second driving lines corresponding to the stepped structures located at different positions in each MEMS galvanometer are all electrically connected to different second driving voltage terminals. For example, the second driving lines 82 corresponding to the stepped structures with different thicknesses in each MEMS galvanometer are all electrically connected to different second driving voltage terminals (+). That is, the MEMS galvanometer array provided by the embodiments of the present disclosure can use digital signals to multi-channel control the steering electrodes on the basis of achieving a larger scanning range. Not only can it be powered simultaneously to achieve the same effect as Figure 35, but it can also determine the on and off of different step structures based on the torsion angle of the reflector. For example, when the reflector is not twisted, the thickest step structure with the smallest distance from the ground electrode is mainly driven. When the reflector is twisted to a certain angle, the thinnest step structure with the largest distance from the ground electrode is mainly driven, achieving various forms of free control. In addition, separately controlling the stepped steering electrodes can also reduce power consumption.

[0166] Based on the same inventive concept, an embodiment of the present disclosure further provides a radar system, including the above-mentioned MEMS galvanometer of the embodiment of the present disclosure, or including the above-mentioned MEMS galvanometer array of the embodiment of the present disclosure.

[0167] Alternatively, the radar system may be a laser radar, as shown in Figure 36 . The laser radar comprises a laser emitting assembly, a beam receiving assembly, and an optical scanning assembly. The laser emitting assembly is used to emit a laser beam; the beam receiving assembly is used to receive an echo beam. The optical scanning assembly is a MEMS galvanometer mirror as described in any of the aforementioned embodiments, which is used to reflect the laser beam and then illuminate the scanning environment, and then reflect the echo beam reflected from the scanning environment back to the beam receiving assembly.

[0168] Embodiments of the present disclosure provide a MEMS galvanometer, a MEMS galvanometer array, and a radar system. When a ground electrode and a substrate are parallel, the distance between a first steering electrode and the ground electrode is configured to gradually decrease from the outside of the reflector to the inside, and the distance between a second steering electrode and the ground electrode is configured to gradually decrease from the outside of the reflector to the inside. That is, the distances between the first steering electrode and the ground electrode and the distances between the second steering electrode and the ground electrode are configured to change in a step-like manner. Since the smaller the distances between the first steering electrode, the second steering electrode, and the ground electrode, the greater the capacitance, the greater the electrostatic adsorption force between the first steering electrode, the second steering electrode, and the ground electrode. This allows the electrostatic adsorption force to be increased by reducing the spacing between the steering electrode group and the ground electrode without reducing the maximum torsion angle of the reflector. Thus, for the same electrostatic adsorption force, the present disclosure can reduce the driving voltage and power consumption. Furthermore, when the ground electrode deflects, the step-like change in distance creates a larger gap between the ground electrode and the first steering electrode or the second steering electrode, which helps reduce adhesion between the ground electrode and the first steering electrode or the second steering electrode, thereby reducing the probability of attraction.

[0169] Although the preferred embodiments of the present disclosure have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present disclosure.

[0170] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present disclosure without departing from the spirit and scope of the embodiments of the present disclosure. Thus, if such changes and modifications of the embodiments of the present disclosure fall within the scope of the claims of the present disclosure and their equivalents, the present disclosure is intended to include such changes and modifications.

Claims

1. A MEMS galvanometer, wherein: include: An outer frame, wherein the outer frame is a hollow structure; A rotating structure, the rotating structure is located in the hollow area of ​​the outer frame, the rotating structure includes a reflector frame and a pair of rotating shafts connected between the reflector frame and the outer frame, and the reflector frame includes a ground electrode; A reflector, located on the reflector frame; A base, wherein the base and the outer frame form a cavity; A steering electrode group is located on the side of the substrate facing the rotating structure, and the steering electrode group includes a first steering electrode and a second steering electrode arranged on both sides of the pair of rotating shafts; wherein, When the ground electrode and the substrate are parallel, the distance between the first steering electrode and the ground electrode gradually decreases from the outside to the inside of the reflector, and the distance between the second steering electrode and the ground electrode gradually decreases from the outside to the inside of the reflector.

2. The MEMS galvanometer according to claim 1, wherein: The surface of the substrate facing the reflector is a flat surface. The first steering electrode and the second steering electrode each include at least two step structures with thickness gradually increasing from the outside to the inside of the reflector. Each of the step structures serves as a sub-electrode.

3. The MEMS galvanometer according to claim 1, wherein: The substrate has at least two step structures at positions corresponding to the first steering electrode and the second steering electrode, the thickness of which gradually increases from the outer side to the inner side of the reflector, and the first steering electrode and the second steering electrode are arranged on the corresponding step structures.

4. The MEMS galvanometer according to claim 2 or 3, wherein: A first angle is formed between the inclined surface formed by each steering electrode and the substrate, and a second angle is formed between the reflector frame and the substrate after being twisted at the maximum angle. The first angle is smaller than the second angle.

5. The MEMS galvanometer according to claim 1, wherein: The ground electrode faces the surface of the substrate and has at least two step structures whose thickness gradually increases from the outside to the inside of the reflector at positions corresponding to the first steering electrode and the second steering electrode.

6. The MEMS galvanometer according to claim 3 or 5, wherein: The first steering electrode and the second steering electrode each include sub-electrodes arranged corresponding to the stepped structure, and each of the sub-electrodes has the same thickness.

7. The MEMS galvanometer according to claim 2 or 6, wherein: There is a gap between each two adjacent sub-electrodes in the first steering electrode and the second steering electrode.

8. The MEMS galvanometer according to claim 7, wherein: It also includes a first isolation layer arranged on the side of the steering electrode group facing the ground electrode, and the orthographic projection of the first isolation layer on the substrate covers the substrate and fills the gap.

9. The MEMS galvanometer according to any one of claims 2 to 8, wherein: The width of each of the step structures corresponding to the first steering electrode gradually increases from the outer side to the inner side of the reflector, and the width of each of the step structures corresponding to the second steering electrode gradually increases from the outer side to the inner side of the reflector.

10. The MEMS galvanometer according to any one of claims 1 to 9, wherein: The outer frame and the rotating structure are an integrated structure formed by using a silicon substrate, and the reflector frame is reused as the ground electrode.

11. The MEMS galvanometer according to any one of claims 1 to 10, wherein: The pair of rotation axes are located on the same straight line and coincide with the central axis of the reflector, and the first steering electrode and the second steering electrode are symmetrically distributed on both sides of the central axis of the reflector.

12. The MEMS galvanometer according to any one of claims 1 to 11, wherein: The shape of the reflector is the same as that of the reflector frame, and the size of the reflector is the same as that of the reflector frame.

13. The MEMS galvanometer according to claim 12, wherein: The shape of the reflector includes a circle or an ellipse, and the rotating shaft is connected to the outer annular surface of the reflector frame.

14. The MEMS galvanometer according to claim 12, wherein: The reflector is in a square shape, a pair of side edges of the reflector frame have a concave structure, and the rotating shaft is embedded in the concave structure and connected to the reflector frame.

15. The MEMS galvanometer according to any one of claims 2 to 9, wherein: Also includes: A plurality of contact electrodes are arranged between the steering electrode group and the substrate and are arranged one-to-one with the step structure, a first driving structure is arranged between the contact electrode and the substrate and corresponds to the first steering electrode, and a second driving structure is arranged between the contact electrode and the substrate and corresponds to the second steering electrode; wherein, The first steering electrode is electrically connected to the corresponding contact electrode, and the second steering electrode is electrically connected to the corresponding contact electrode; The contact electrodes corresponding to the first steering electrodes are electrically connected to the first driving structure, and the contact electrodes corresponding to the second steering electrodes are electrically connected to the second driving structure.

16. The MEMS galvanometer according to claim 15, wherein: The first driving structure comprises: a first driving electrode electrically connected to each of the contact electrodes corresponding to the first steering electrode, and a first driving line electrically connected to the first driving electrode; The second driving structure includes: a second driving electrode electrically connected to each of the contact electrodes corresponding to the second steering electrode, and a second driving line electrically connected to the second driving electrode.

17. The MEMS galvanometer according to claim 15, wherein: The first driving structure comprises: first driving electrodes electrically connected to the contact electrodes corresponding to the first steering electrodes in a one-to-one correspondence, and first driving lines electrically connected to the first driving electrodes in a one-to-one correspondence; The second driving structure includes: second driving electrodes electrically connected to the contact electrodes corresponding to the second steering electrodes in a one-to-one correspondence, and second driving lines electrically connected to the second driving electrodes in a one-to-one correspondence.

18. The MEMS galvanometer according to claim 17, wherein: Also includes: A second isolation layer is arranged between the contact electrode and the first drive structure, the second drive structure, and a third isolation layer is arranged between the contact electrode and the steering electrode group; wherein the second isolation layer exposes the first drive electrode and the second drive electrode, and the third isolation layer exposes the contact electrode.

19. A MEMS galvanometer array, wherein: It comprises a plurality of MEMS galvanometers as described in any one of claims 1 to 18 arranged in an array.

20. The MEMS galvanometer array according to claim 19, wherein: The first steering electrode in each of the MEMS galvanometers corresponds to one or multiple first driving lines which are equal to the number of the step structures, and the second steering electrode in each of the MEMS galvanometers corresponds to one or multiple second driving lines which are equal to the number of the step structures. Each of the first driving lines in each of the MEMS galvanometers is electrically connected to the same first driving voltage terminal, and each of the second driving lines in each of the MEMS galvanometers is electrically connected to the same second driving voltage terminal.

21. The MEMS galvanometer array according to claim 19, wherein: The first steering electrode in each of the MEMS galvanometers corresponds to a plurality of first driving lines having the same number as the step structure, and the second steering electrode in each of the MEMS galvanometers corresponds to a plurality of second driving lines having the same number as the step structure; wherein, The first driving lines corresponding to the step structures at the same position in the MEMS galvanometers are electrically connected to the same first driving voltage terminal, and the first driving lines corresponding to the step structures at different positions in the MEMS galvanometers are electrically connected to different first driving voltage terminals; The second driving lines corresponding to the stepped structures at the same position in the MEMS galvanometers are electrically connected to the same second driving voltage terminal, and the second driving lines corresponding to the stepped structures at different positions in the MEMS galvanometers are electrically connected to different second driving voltage terminals.

22. A radar system, wherein: It comprises the MEMS galvanometer as claimed in any one of claims 1 to 18, or comprises the MEMS galvanometer array as claimed in any one of claims 19 to 21.

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