Micro electro mechanical system micromirror, optical equipment and optical communication equipment

Abstract

The embodiment of the invention provides a micro-electro-mechanical system micro-mirror, optical equipment and optical communication equipment, relates to the technical field of micro-electro-mechanical systems, and aims to solve the problem that the MEMS micro-mirror has contradictions among double-shaft independent driving, packaging size and device weight. The MEMS micro-mirror comprises a micro-mirror chip and a magnet unit, wherein the micro-mirror chip comprises a reflecting mirror, a first frame, a first torsion beam, a second frame, a second torsion beam and a fixed anchor point; the reflector is arranged on the first frame, the first frame is connected with the second frame through the first torsion beam, and the second frame is connected with the fixed anchor point through the second torsion beam. A first coil and a second coil are arranged in the first frame and the second frame respectively; a hollow area is arranged between the first frame and the second frame. The magnet unit is arranged at a position opposite to the hollow area and comprises a first magnet and a second magnet; the first magnet and the second magnet are driving magnets of the first coil and the second coil respectively. The MEMS micromirror can be applied to optical equipment and optical communication equipment.

Description

Technical Field

[0001] This application relates to the field of microelectromechanical systems (MEMS) technology, and in particular to a micromirror, optical device, and optical communication device for a MEMS system. Background Technology

[0002] Microelectromechanical system micromirrors (MEMS micromirrors) are MEMS devices that integrate a mirror and a MEMS actuator, manufactured using Micro-Electro-Mechanical System (MEMS) technology. They offer advantages such as light weight, small size, and low cost. As important components in optical application systems, MEMS micromirrors have been widely used in laser projection displays, barcode scanning, and self-focusing micromicroscopes.

[0003] Based on their actuation methods, MEMS micromirrors are mainly classified into electrostatic actuation, electromagnetic actuation (also known as magnetoelectric actuation), piezoelectric actuation, and electrothermal actuation. Based on their scanning dimensions, MEMS micromirrors can be divided into single-axis and dual-axis types. Dual-axis MEMS micromirrors using electromagnetic actuation are a widely used type.

[0004] However, the electromagnetically driven dual-axis MEMS micromirrors provided in the related technologies have certain contradictions between independent dual-axis drive and package size and device weight. That is, products that can achieve independent dual-axis drive have large package size and heavy device weight, while products with small package size and light device weight cannot achieve independent dual-axis drive. Dual-axis motion that cannot be driven independently has problems such as large coupling crosstalk and poor motion control accuracy. Summary of the Invention

[0005] This application provides a micromirror for a microelectromechanical system (MEMS), an optical device, and an optical communication device, which can improve the contradiction between dual-axis independent drive and package size and device weight in MEMS micromirrors.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, a micromirror for a microelectromechanical system (MEMS) is provided, comprising a micromirror chip and a magnet unit. The micromirror chip includes a reflector, a first frame, a first torsion beam, a second frame, a second torsion beam, and a fixing anchor point. The reflector is disposed on the first frame, and the second frame is sleeved on the outside of the first frame. The first frame is connected to the second frame via the first torsion beam, and the second frame is connected to the fixing anchor point via the second torsion beam. A first coil is disposed in the first frame to drive the first frame to rotate around the first torsion beam; a second coil is disposed in the second frame to drive the second frame to rotate around the second torsion beam; a hollow area exists between the first and second frames.

[0008] The magnet unit is positioned opposite the hollowed-out area and includes a first magnet and a second magnet; the first magnet is the driving magnet for the first coil, and the second magnet is the driving magnet for the second coil.

[0009] In the microelectromechanical system micromirror (MEMS micromirror) provided in this application, by adopting a dual-coil design of a first coil and a second coil for the micromirror chip and a dual-magnet design of a first magnet and a second magnet for the magnet unit, the magnetic fields driving the first coil and the second coil can be separated. This is beneficial for driving the dual-axis motion of the MEMS micromirror individually and simultaneously through the dual coils, and can avoid mechanical crosstalk between the dual-axis motions, thereby improving the motion control accuracy of the MEMS micromirror.

[0010] In the MEMS micromirror provided in this application, by adopting a design that positions the magnet unit relative to the hollowed-out area in the micromirror chip, the internal space of the micromirror chip can be rationally utilized, making the structure of the MEMS micromirror more compact, thereby facilitating the reduction of the package size of the MEMS micromirror. Furthermore, by placing both the first and second magnets in the magnet unit inside the micromirror chip, with the first magnet close to the first coil and the second magnet close to the second coil, the stronger magnetic field of the magnets can be directly used to generate an Ampere force on the coils. Therefore, the driving capability of the MEMS micromirror can be improved, or, while ensuring the driving capability of the MEMS micromirror, the volume and weight of the first and second magnets can be significantly reduced, thereby facilitating miniaturization and weight reduction in packaging.

[0011] It can be seen that the MEMS micromirrors provided in this application can improve the contradiction between dual-axis independent drive and package size and device weight.

[0012] In some possible implementations, the axis of the first torsion beam is a first axis, and the axis of the second torsion beam is a second axis; the first axis and the second axis are perpendicular to each other. The first frame includes two first frame portions located on both sides of the first axis, and the first frame portions have a structure that gradually convexes outward as they move along the first axis toward the second axis.

[0013] The second frame includes two second frame sections located on both sides of the second axis and parallel to the second axis, and the second frame sections are connected to the first torsion beam.

[0014] In the MEMS micromirror provided in this application, the portion of the first frame located on both sides of the first axis adopts an outward convex design. This design, compared to a portion of the first frame parallel to the first axis, is advantageous in increasing the extension distance of the first coil in the magnetic field, thereby improving the driving capability of the MEMS micromirror. Furthermore, the portion of the second frame connected to the first torsion beam is designed to be parallel to the second axis, which allows for the formation of a larger hollow area in conjunction with the first frame while maintaining the same overall size; this facilitates the placement of the magnet unit.

[0015] In some possible implementations, the cutout area is divided into four sub-regions according to a first axis and a second axis. The magnet assembly includes four magnet units, each disposed in the mounting substrate at a position opposite to one of the four sub-regions.

[0016] The micromirror of the microelectromechanical system includes four magnet units, which are respectively positioned opposite to the four sub-regions.

[0017] This design allows for the placement of four magnet units in the hollowed-out area between the first and second frames. The four magnet units are distributed in pairs relative to the first and second axes, thereby providing driving magnetic fields for the first and second coils on both sides of the first and second axes in more locations, which in turn helps to improve the driving capability of the MEMS micromirror.

[0018] In some possible implementations, the magnet unit further includes an iron core column, the outer peripheral surface of which includes a first side surface and a second side surface. The first side surface is opposite to a first frame portion at the edge of the sub-region, and a first magnet is attached to the first side surface. The second side surface is opposite to a second frame portion at the edge of the sub-region, and a second magnet is attached to the second side surface.

[0019] This design allows for several advantages. First, it enables the use of iron core pillars to achieve magnetic conductivity and enhance magnetic field strength, resulting in a more accurate and stronger magnetic field distribution. Second, it matches the shape characteristics of the sub-region, allowing the first magnet on the iron core pillar to be parallel to the first frame portion at the edge of the sub-region, and the second magnet to be parallel to the second frame portion at the edge of the sub-region. This reduces the space required for the magnet unit, which is beneficial for reducing the packaging size of MEMS micromirrors.

[0020] In some possible implementations, the first side is parallel to the opposite first coil, and the first magnet is a magnetic sheet extending from the first side, with two magnetic poles arranged in a direction perpendicular to the first side. This design allows the magnet unit to generate a magnetic field perpendicular to the first coil, thereby improving the driving capability of the MEMS micromirror.

[0021] In some possible implementations, the second side is parallel to the opposing second coil, and the second magnet is a magnetic sheet extending from the second side, with two magnetic poles arranged in a direction perpendicular to the second side. This design allows the magnet unit to generate a magnetic field perpendicular to the second coil, thereby improving the driving capability of the MEMS micromirror.

[0022] In some possible implementations, in two magnet units located on the same side of the first axis, the two iron core columns are connected as a single structure, the two first side surfaces are connected as one side surface, and the two first magnets are connected as a single structure. This design simplifies the structure of the magnet units in the magnet assembly and simplifies the manufacturing process of the magnet assembly.

[0023] In some possible implementations, the microelectromechanical system micromirror also includes a mounting substrate on which the iron core post is mounted.

[0024] Relative to the mounting substrate, the bottom height of the first magnet in the magnet unit is the first height, and the top height is the second height; the bottom height of the second magnet is the third height, and the top height is the fourth height; the height of the micromirror chip is the fifth height.

[0025] The first and third heights are both lower than the fifth height; the second and fourth heights are both higher than or equal to the fifth height. This design ensures that the first coil is positioned in a location with a strong magnetic field in the magnetic field generated by the first magnet, and the second coil is positioned in a location with a strong magnetic field in the magnetic field generated by the second magnet; furthermore, during rotation around the first and second torsion beams, both the first and second coils experience strong magnetic fields passing through them.

[0026] In some possible implementations, the second and fourth heights are both higher than or equal to the fifth height, and lower than or equal to twice the fifth height. This design, on the one hand, avoids interference with the movement of the moving parts in the micromirror chip by limiting the proportion of the magnet unit above the micromirror chip. On the other hand, it places the first and second coils as close as possible to the region of strongest magnetic field of their respective magnets.

[0027] In some possible implementations, the microelectromechanical system (MEMS) micromirror also includes a mounting substrate on which a core post is disposed. The mounting substrate has mounting grooves on the outer bottom of the core post, in which a first magnet and a second magnet are mounted. This design facilitates the installation and fixation of the first and second magnets to the core post, improving the assembly reliability of the first and second magnets with the core post.

[0028] In some possible implementations, the core post and the mounting substrate are an integral structure made of soft magnetic material. This design allows both the mounting substrate and the core post to function as a core; since the mounting substrate can cover a larger area of ​​the micromirror chip compared to the core post, it can further enhance the magnetic field strength. Furthermore, the integral structure of the core post and the mounting substrate facilitates the fabrication of both and ensures reliable connection between them.

[0029] In some possible implementations, in two magnet units located on the same side of the second axis, the two first magnets have different magnetic poles near the first coil, and the two second magnets have the same magnetic poles near the second coil; in two magnet units located on the same side of the first axis, the two first magnets have the same magnetic poles near the first coil, and the two second magnets have different magnetic poles near the second coil.

[0030] This design allows the magnetic fields generated by the first magnets in different magnet units to be concentrated near the first coil at the edge of the sub-region. On one side of the first axis, the magnetic field extends from the two sub-regions toward the first frame in a direction perpendicular to the first coil at the edge of the corresponding sub-region; on the other side of the first axis, the magnetic field extends from the first frame toward the two sub-regions in a direction perpendicular to the first coil at the edge of the two sub-regions. In this distributed magnetic field, when the first coil is energized, the Ampere force experienced by the four coil parts located at the edges of the four sub-regions can drive the first frame to rotate around the first torsion beam, thereby causing the reflector to rotate around the first axis.

[0031] On the other hand, the magnetic field generated by the second magnet in different magnet units can be concentrated near the edge of the second frame portion of the sub-region. On one side of the second axis, the magnetic field extends from the hollowed-out area inside the second frame in a direction perpendicular to the second coil in the second frame portion to the outside of the second frame; on the other side of the second axis, the magnetic field extends from the outside of the second frame in a direction perpendicular to the second coil in the second frame portion to the hollowed-out area inside the second frame. In addition, although there is also a magnetic field distribution in the third frame portion of the second frame, the magnetic field strength is small, and the magnetic field direction is different at different positions in the first direction, thus having a certain degree of cancellation. In this magnetic field distribution, after the second coil is energized, the Ampere force on the two parts of the second coil located in the two second frame portions can drive the second frame to rotate around the second torsion beam, thereby driving the reflector to rotate around the second axis. The Ampere force on the two parts of the second coil located in the two third frame portions is basically zero.

[0032] In some possible implementations, the first frame is a rhombus or square with its diagonals coinciding with the first axis and the second axis, or a circle with its center coinciding with the intersection of the first axis and the second axis, or an ellipse with its major axis and minor axis coinciding with the first axis and the second axis, or an ellipse with its major axis and minor axis coinciding with the second axis and the first axis, respectively.

[0033] The MEMS micromirrors provided in this application can adopt a variety of first frames with different shapes, and the structural design is flexible and adaptable; they can be applied to different application scenarios.

[0034] In some possible implementations, the first coil is arranged around the reflector in the first frame and extends to a fixed anchor point via a first torsion beam, a second frame, and a second torsion beam. This design allows direct drive of the first frame via the first coil, thereby directly driving the reflector to rotate around the first torsion beam; it also helps to mitigate motion crosstalk issues between rotation around the second torsion beam and rotation around the second torsion beam.

[0035] In some possible implementations, the first frame and the reflector are an integral structure, with the outer periphery of the reflector connected to the first frame. That is, there is no opening between the reflector and the first frame; this design helps to reduce the area occupied by the reflector and the first frame.

[0036] In some possible implementations, the anchor point is located inside the first frame and within the cutout area. This design makes full use of the area between the first and second frames, resulting in a more compact MEMS micromirror structure and facilitating a reduction in the package size of the MEMS micromirror.

[0037] In some possible implementations, the anchor point is located outside the first frame. The MEMS micromirror provided in this application can also be a structure with the anchor point externally mounted; when the anchor point is externally mounted, the above-mentioned technical effects can still be achieved.

[0038] In some possible implementations, the second frame includes a recessed portion that is recessed towards the first frame at a location on the second axis, and the recessed portion is connected to the fixing anchor point via a second torsion beam. This design allows for a reduction in the size of the MEMS micromirror package even when the fixing anchor point is external, by utilizing the area between the first and second frames.

[0039] In some possible implementations, the first torsion beam is a straight beam, a folded beam, a curved beam, or a serpentine beam, and the second torsion beam is also a straight beam, a folded beam, a curved beam, or a serpentine beam. In the MEMS micromirror provided in this application, both the first and second torsion beams can be selected from different types of beams, allowing for flexible structural design to match different application scenarios.

[0040] In some possible implementations, the micromirror of the microelectromechanical system (MEMS) further includes angle sensors disposed on the first torsion beam and / or the second torsion beam; the angle sensors are Hall sensors or piezoresistive sensors. This design allows for the detection and feedback of the torsion angle of the first torsion beam and / or the second torsion beam during MEMS micromirror operation, thereby facilitating closed-loop control of the MEMS micromirror.

[0041] Secondly, this application also provides an optical device, which includes a light source and a microelectromechanical system (MEMS) micromirror as described in the first aspect, wherein a reflector in the MEMS micromirror is used to reflect the light beam emitted by the light source.

[0042] Thirdly, this application also provides an optical communication device, which includes an input port, an output port, and a microelectromechanical system (MEMS) micromirror as described in the first aspect; the input port is used to receive optical signals and project the optical signals onto the MEMS micromirror; the reflector in the MEMS micromirror is used to reflect the optical signals to the output port.

[0043] The technical effects achievable by the optical equipment and optical communication equipment provided in this application are the same as those achievable by the microelectromechanical system micromirror described in the first aspect, and will not be repeated here. Attached Figure Description

[0044] Figure 1 A schematic diagram of an electromagnetically driven biaxial MEMS micromirror provided for related technologies;

[0045] Figure 2 This is a schematic diagram of the structure of a MEMS micromirror provided in an embodiment of this application;

[0046] Figure 3 for Figure 2 Schematic diagram of the structure of the micromirror chip;

[0047] Figure 4 for Figure 2 A schematic diagram of the coil of a micromirror chip;

[0048] Figure 5 for Figure 3 Cross-sectional view of the middle reflecting mirror;

[0049] Figure 6 for Figure 2 Schematic diagram of the structure of the central magnet assembly;

[0050] Figure 7 for Figure 2 A schematic diagram of the central magnet assembly from another angle;

[0051] Figure 8 for Figure 6 A schematic diagram of the structure for mounting the base plate and the iron core column;

[0052] Figure 9 This is a schematic diagram of a magnetic circuit design in a magnet assembly provided in an embodiment of this application;

[0053] Figure 10 for Figure 9 A schematic diagram of magnetic field lines in the image;

[0054] Figure 11 This is a schematic diagram of another MEMS micromirror structure provided in an embodiment of this application;

[0055] Figure 12 This is a schematic diagram of another MEMS micromirror provided in the embodiments of this application;

[0056] Figure 13 A flowchart illustrating a method for fabricating a micromirror chip, as provided in an embodiment of this application;

[0057] Figure 14 This is a schematic diagram of the structure of a lidar provided in an embodiment of this application;

[0058] Figure 15 This is a schematic diagram of the structure of a projection device provided in an embodiment of this application. Detailed Implementation

[0059] Micro-Electro-Mechanical Systems (MEMS), also known as micro-electromechanical systems, microsystems, or micromachines, are high-tech electromechanical devices developed based on microelectronics technology (semiconductor manufacturing technology). They integrate technologies such as photolithography, etching, thin film fabrication, silicon micromachining, non-silicon micromachining, and precision machining. The dimensions of MEMS are generally on the micrometer or even nanometer scale.

[0060] Microelectromechanical systems (MEMS) micromirrors (also known as MEMS scanning mirrors or MEMS galvanometers) are MEMS devices that integrate a mirror and a MEMS actuator, manufactured using MEMS technology. Based on the driving method, MEMS micromirrors are mainly classified into electrostatic driving, electromagnetic driving (also known as magnetoelectric driving), piezoelectric driving, and electrothermal driving. Electromagnetic driving utilizes the Ampere force experienced by a current-carrying coil in a magnetic field as the driving force to drive the mirror to twist around its axis. Electromagnetic driving has the technical advantages of large twisting angles, low driving voltage, and the ability to achieve linear driving.

[0061] Depending on the scanning dimension, MEMS micromirrors can be divided into single-axis and dual-axis. The former can scan around one axis in one dimension, also known as a one-dimensional MEMS micromirror; the latter can scan around two different axes in two dimensions, also known as a two-dimensional MEMS micromirror.

[0062] MEMS micromirrors can operate in two modes: resonant and quasi-static (i.e., non-resonant). When the frequency of the driving signal is close to or equal to the resonant frequency of the MEMS micromirror, the MEMS micromirror operates in a mechanical resonant state. In this state, the MEMS micromirror rotates continuously and periodically, with the rotation period equal to the frequency of the driving signal; the scanning angle has a sinusoidal relationship with time; and it has advantages such as a large scanning angle, low driving power consumption, and low scanning voltage.

[0063] When the frequency of the driving signal is much lower than the resonant frequency of the MEMS micromirror, the MEMS micromirror operates in a non-resonant state, i.e., quasi-static. In this state, the MEMS micromirror can scan or pause at any angle within the scanning range. The scanning angle range is relatively small, and the required driving force is much higher than that in the resonant state.

[0064] The MEMS micromirror provided in this application is a biaxial MEMS micromirror driven by electromagnetic force. The following will further describe this type of MEMS micromirror (hereinafter referred to as MEMS micromirror).

[0065] like Figure 1 As shown, the MEMS micromirror 1 provided by related technologies typically includes a micromirror chip 2 and a magnet assembly 9. The micromirror chip 2 includes a reflector 7, a first torsion beam 8, a movable frame 5, a drive coil 6, a second torsion beam 4, and a fixed anchor point 3. The movable frame 5 is fitted around the outer periphery of the reflector 7, and the reflector 7 is connected to the movable frame 5 via the first torsion beam 8. The drive coil 6 extends around the reflector 7 within the movable frame 5. The fixed anchor point 3 is located outside the movable frame 5, and the movable frame 5 is connected to the fixed anchor point 3 via the second torsion beam 4. The axes of the first torsion beam 8 and the second torsion beam 4 are perpendicular to each other.

[0066] The magnet assembly 9 is disposed on the outer periphery of the micromirror chip 2 and includes two magnets arranged opposite each other. Both magnets are L-shaped magnets and are used to generate a magnetic field in the region where the micromirror chip 2 is located, with the magnetic field direction inclined relative to both the first torsion beam 8 and the second torsion beam 4.

[0067] When the drive coil 6 is energized during operation, it experiences an Ampere force while in a magnetic field. Under the influence of this Ampere force, the movable frame 5 can be driven to rotate around the second torsion beam 4 in a resonant or quasi-static manner, or the reflector 7 can be driven to rotate around the first torsion beam 8 in a resonant manner, thus achieving the purpose of driving the reflector 7 to rotate around two different axes.

[0068] In the MEMS micromirror 1 provided by the aforementioned related technology, since the magnet assembly 9 is located on the outer periphery of the micromirror chip 2 and is far from the reflector 7 and the first torsion beam 8, the Ampere force on the coil used to drive the first torsion beam 8 is too small to meet the driving requirements when the coil is placed near the reflector 7. Based on this, the MEMS micromirror 1 adopts a single-coil design, using a single driving coil 6 to drive the MEMS micromirror 1 to achieve dual-axis motion. However, since the first torsion beam 8 cannot be directly driven, this results in significant mechanical crosstalk between the dual-axis motions, thus affecting the control accuracy of the MEMS micromirror 1.

[0069] In some other related technologies, to achieve the goal of driving the first torsion beam 8 and the second torsion beam 4 separately using dual coils, one approach is to place the magnet assembly 9 below the micromirror chip 2, allowing the magnet to be close to both the first torsion beam 8 and the second torsion beam 4 simultaneously. However, to avoid interference between the magnet assembly 9 and the moving parts in the micromirror chip 2, the magnet assembly 9 located below the micromirror chip 2 needs to maintain a certain distance from the micromirror chip 2. This results in the micromirror chip 2 still being relatively far from the magnet in the magnet assembly 9, and thus unable to utilize the strongest magnetic field region of the magnet.

[0070] Another approach is to increase the size of the magnets to provide sufficient magnetic field strength. In designs where the magnet assembly 9 is positioned below the micromirror chip 2, an iron core can also be used to further increase the magnetic field strength. However, this would lead to an increase in package size and overall weight.

[0071] Another approach is to compensate for a weak magnetic field strength by increasing the drive current. However, this approach will increase the power consumption of the device and also cause the temperature of the micromirror chip 2 to rise. The temperature change of the micromirror chip 2 may also lead to a decrease in control accuracy, which will affect the performance of the MEMS micromirror 1.

[0072] It can be seen that there is a certain contradiction between the MEMS micromirror 1 provided in the related technology and the package size and device weight. That is, the products that can achieve independent dual-axis drive have the problem of large package size and large device weight, while the products with small package size and small device weight cannot achieve independent dual-axis drive. The dual-axis motion that cannot be driven independently has problems such as large coupling crosstalk and poor motion control accuracy.

[0073] Based on this, embodiments of this application provide a micromirror for microelectromechanical systems (MEMS) to improve the above-mentioned problems.

[0074] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0075] In the following embodiments of this application, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0076] In the embodiments of this application, "upper", "lower", "left" and "right" are not limited to the orientation of the components in the accompanying drawings. It should be understood that these directional terms can be relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the components in the accompanying drawings.

[0077] In the embodiments of this application, unless the context otherwise requires, the term "comprising" is interpreted as open and encompassing throughout the specification and claims, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "exemplarily," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this application. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0078] As used herein, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from the given value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the given quantity (i.e., the limitations of the measurement system).

[0079] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°; “equal” includes absolute equality and approximate equality, where an acceptable range of deviation for approximate equality may be, for example, a difference between the two equals being less than or equal to 5% of either one.

[0080] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0081] Exemplary embodiments are described in this application with reference to cross-sectional views and / or plan views and / or equivalent circuit diagrams, which are idealized exemplary drawings. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched regions shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0082] This application provides a microelectromechanical system (MEMS) micromirror, which is an electromagnetically driven biaxial MEMS micromirror. The two rotation axes of this biaxial micromirror are a first axis and a second axis, which are parallel to a first direction and a second direction that are perpendicular to each other. The first axis, second axis, first direction, second direction, and third direction are used as references in the following illustrative description of the MEMS micromirror provided in this application. The first direction, second direction, and third direction are all mutually perpendicular.

[0083] like Figure 2 and Figure 3 As shown, the MEMS micromirror 1 includes a micromirror chip 2 and a magnet assembly 9. The micromirror chip 2 is a plate-shaped structure formed by processing a semiconductor substrate using semiconductor processing technology. It includes a reflector 7, a first frame 12, a first torsion beam 8, a second frame 13, a second torsion beam 4, and a fixing anchor point 3. The reflector 7 is disposed on the first frame 12, which is a symmetrical structure with respect to both the first axis O1 and the second axis O2, including first frame portions 121 located on both sides of the first axis O1. As the first frame portion 121 approaches the second axis O2 along the first direction X (first axis O1), it gradually convexes outward. That is, the dimension of the first frame 12 in the second direction Y is the width of the first frame 12, and the width of the first frame 12 gradually increases as it approaches the middle position from both ends along the first direction X.

[0084] For example, the shape of the first frame 12 can be a rhombus or a square whose diagonals coincide with the first axis O1 and the second axis O2, respectively (the apex corners can be ground flat). Another example is that the shape of the first frame 12 is a circle whose center coincides with the intersection of the first axis O1 and the second axis O2. Yet another example is that the shape of the first frame 12 is an ellipse, whose major and minor axes coincide with the first axis O1 and the second axis O2, respectively, or whose major and minor axes coincide with the second axis O2 and the first axis O1, respectively.

[0085] In this embodiment, as Figure 1 and Figure 2 As shown, the first frame 12 is rhomboid in shape (the top corners are ground flat). The two diagonals of the rhombus are of different lengths, and the longer diagonal coincides with the first axis O1, while the shorter diagonal coincides with the second axis O2.

[0086] like Figure 4 As shown, the first frame 12 also includes a first coil 14 extending around the first frame 12 at the edge position, and the reflector 7 is disposed inside the first coil 14, that is, the first coil 14 extends around the reflector 7.

[0087] The reflector 7 and the first frame 12 are an integral structure, and in this embodiment, there is no cutout between the first frame 12 and the reflector 7; that is, the outer periphery of the reflector 7 is in contact with the first frame 12. This design helps to reduce the area occupied by the reflector 7 and the first frame 12. In some embodiments, there is a cutout between the first frame 12 and the reflector 7; this cutout design can reduce the weight of the reflector 7 and the first frame 12.

[0088] The reflector 7 on the first frame 12 is used to reflect incident light, and the optical performance of the reflector 7 has a significant impact on the performance of the MEMS micromirror 1. For example, as shown in... Figure 5 As shown, the reflector 7 typically includes a reflective layer 71, a mirror layer 72, and a support structure 73. The reflective layer 71 is usually composed of a single or multiple metal reflective film, commonly made of materials such as aluminum (Al), silver (Ag), or gold (Au). The reflective layer 71 is disposed on one side of the mirror layer 72, and the support structure 73 is disposed on the other side of the mirror layer 72. The thickness of the support structure 73 is generally not less than that of the mirror layer 72, and it is used to enhance the rigidity of the mirror layer 72 and reduce the deformation of the mirror layer 72.

[0089] The shape of the reflector 7 can be the same as that of the first frame 12, or it can be any shape extending from the first frame 12. In this embodiment, the reflector 7 is an ellipse with its major axis coinciding with the first axis O1 and its minor axis coinciding with the second axis O2.

[0090] Please continue to refer to this. Figure 2 and Figure 3 The second frame 13 is fitted around the outer periphery of the first frame 12. It can be a square frame parallel to the first axis O1 and the second axis O2, and this square frame is symmetrical with respect to both the first axis O1 and the second axis O2. The second frame 13 includes two second frame portions 131 located on both sides of the second axis O2 and parallel to the second axis O2, and two third frame portions 132 located on both sides of the first axis O1 and parallel to the first axis O1. The two second frame portions 131 are arranged opposite each other in the first direction X, and the two third frame portions 132 are arranged opposite each other in the second direction Y. The third frame portions 132 are used to connect the ends of the two second frame portions 131 on the same side. The two second frame portions 131 and the two third frame portions 132 are connected to form a closed square frame. Figure 4 As shown, a second coil 15 extending along the second frame 13 is also provided in the second frame 13, and the second coil 15 extending along the second frame 13 extends around the first frame 12.

[0091] The outer side of the first frame 12 is connected to two second frame sections 131 respectively via a first torsion beam 8 at the location of the first axis O1. The central axis of the first torsion beam 8 is the first axis O1, and it can be a straight beam, a folded beam, a curved beam, or a serpentine beam. The first coil 14 in the first frame 12 extends into the second frame 13 via the first torsion beam 8. In this embodiment, as... Figure 2 and Figure 3 As shown, the first torsion beam 8 is a straight beam.

[0092] There is a hollow area 10 between the first frame 12 and the second frame 13. For ease of description, the hollow area 10 between the first frame 12 and the second frame 13 is divided into four sub-regions 11 according to the first axis O1 and the second axis O2. The four sub-regions 11 are symmetrically distributed in pairs on both sides of the first axis O1 and symmetrically distributed in pairs on both sides of the second axis O2. The edge of each sub-region 11 includes a first frame portion 121 and a second frame portion 131.

[0093] Please continue to refer to this. Figures 2 to 4 In the second frame 13, the third frame portion 132 is connected to the fixed anchor point 3 at the position of the second axis O2 via the second torsion beam 4. The central axis of the second torsion beam 4 is the second axis O2, and it can be a straight beam, a folded beam, a curved beam, or a serpentine beam. The first coil 14 and the second coil 15 in the second frame 13 are connected to the fixed anchor point 3 via the second torsion beam 4. In this embodiment, the second torsion beam 4 adopts a double-sided serpentine beam structure, with the serpentine beam structures on both sides symmetrical about the second axis O2. This design ensures the symmetry of the second torsion beam 4 and facilitates the routing of the first coil 14 and the second coil 15 within it.

[0094] A connecting electrode is provided on the fixed anchor point 3, which is connected to the first coil 14 and the second coil 15. This connecting electrode is used to connect with other conductive structures to bring out the first coil 14 and the second coil 15. For example, the connecting electrode can be connected to an external flexible printed circuit (FPC) by wire bonding. As can be seen from the above description, in this embodiment, the micromirror chip 2 adopts a dual-coil design, with the first torsion beam 8 and the second torsion beam 4 each having their own independent drive coils, namely the first coil 14 and the second coil 15.

[0095] In this embodiment, the MEMS micromirror 1 includes two anchor points 3, which are arranged on the second axis O2 and are internally integrated. Specifically, the two anchor points 3 are located in the hollow area 10 inside the first frame 12 and are symmetrically positioned on both sides of the first frame 12 relative to the first axis O1. The anchor points 3 are located between two sub-regions 11 on the same side of the first axis O1, that is, the two sub-regions 11 on the same side of the first axis O1 are located on both sides of the anchor points 3.

[0096] Please continue to refer to this. Figure 2 The MEMS micromirror 1 also includes a magnet assembly 9. The magnet assembly 9 and the micromirror chip 2 are arranged along a third direction, which can be the thickness direction of the micromirror chip 2, parallel to the height direction of the MEMS micromirror 1. The magnet assembly 9 is disposed on one side of the micromirror chip 2 along the third direction, for example, above or below the micromirror chip 2. The following description, taking the example of the magnet assembly 9 being disposed below the micromirror chip 2, illustrates the structure of the magnet assembly 9 in conjunction with the micromirror chip 2.

[0097] like Figures 6 to 8 As shown, the magnet assembly 9 includes a mounting substrate 91, which is a plate-like structure parallel to the micromirror chip 2, with its thickness direction parallel to the third direction Z. The magnet assembly 9 also includes four magnet units 92 disposed on the side of the mounting substrate 91 closest to the micromirror chip 2. The four magnet units 92 are disposed in four sub-regions 11, respectively. Specifically, the four magnet units 92 are arranged on both sides of the first axis O1 and the second axis O2, that is, the four magnet units 92 are arranged in pairs on both sides of the first axis O1 and also in pairs on both sides of the second axis O2. Two magnet units 92 located on the same side of the first axis O1 are respectively located on both sides of the second axis O2, and two magnet units 92 located on the same side of the second axis O2 are respectively located on both sides of the first axis O1.

[0098] Furthermore, the four magnet units 92 in the magnet assembly 9 can be symmetrical structures with respect to the first axis O1 and the second axis O2; specifically, the two magnet units 92 located on the same side of the second axis O2 and on both sides of the first axis O1 are symmetrical structures with respect to the first axis O1; the two magnet units 92 located on the same side of the first axis O1 and on both sides of the second axis O2 are symmetrical structures with respect to the second axis O2.

[0099] Please continue to refer to this. Figures 6 to 8 The magnet unit 92 includes a core post 921, a first magnet 922, and a second magnet 923. The core post 921 is erected on the mounting substrate 91 and is a columnar structure extending from the mounting substrate 91 in a third direction Z. The core post 921 has an outer peripheral surface extending in a third direction Z, which includes a first side surface 924 and a second side surface 925. When the magnet unit 92 is inserted into a sub-region 11 in the micromirror chip 2, the first side surface 924 is opposite to and extends along the opposite first frame portion 121 at the edge of the sub-region 11; the second side surface 925 is opposite to and extends along the opposite second frame portion 131 at the edge of the sub-region 11.

[0100] For example, such as Figures 6 to 8 As shown, the iron core column 921 is a triangular prism structure extending along the third direction Z. The two connected sides of the outer periphery of the triangular prism are the first side 924 and the second side 925, respectively.

[0101] Please continue to refer to this. Figures 6 to 8 In the magnet unit 92, the first magnet 922 is attached to the first side surface 924 and is a magnetic sheet extending along the first side surface 924; the arrangement direction of the two magnetic poles in the magnetic sheet is perpendicular to the first side surface 924. When the magnet unit 92 is inserted into the sub-region 11 in the micromirror chip 2, the magnetic field generated by the first magnet 922 can cover the first frame portion 121 at the edge of the sub-region 11 and the first coil 14 located at the edge of the sub-region 11; and the direction of the magnetic field is perpendicular to the first coil 14 located at the edge of the sub-region 11. After the first coil 14 is energized, the Ampere force in the magnetic field generated by the first magnet 922 can drive the first frame 12 to twist relative to the second frame 13 around the first torsion beam 8, thereby driving the reflector 7 to rotate around the first axis O1. It can be seen that the first magnet 922 is the driving magnet of the first coil 14.

[0102] The second magnet 923 is attached to the second side surface 925 and is a magnetic sheet extending along the first side surface 924. The arrangement direction of the two magnetic poles in this magnetic sheet is perpendicular to the second side surface 925. When the magnet unit 92 is inserted into the sub-region 11 in the micromirror chip 2, the magnetic field generated by the second magnet 923 can cover the second frame portion 131 at the edge of the sub-region 11 and the second coil 15 located at the edge of the sub-region 11; and the direction of the magnetic field is perpendicular to the second coil 15 located at the edge of the sub-region 11. After the second coil 15 is energized, the Ampere force in the magnetic field generated by the second magnet 923 can drive the second frame 13 to twist relative to the fixed anchor point 3 around the second torsion beam 4, thereby driving the reflector 7 to rotate around the second axis O2. It can be seen that the second magnet 923 is the driving magnet of the second coil 15.

[0103] For ease of description, this paper refers to the following heights relative to the mounting substrate 91: the bottom height of the first magnet 922 in the magnet unit 92 is called the first height, and the top height is called the second height; the bottom height of the second magnet 923 is called the third height, and the top height is called the fourth height; the height of the micromirror chip 2 is called the fifth height, and the height of the iron core column 921 in the magnet unit 92 is called the sixth height. The first and third heights are both lower than the fifth height, and the second and fourth heights are both higher than or equal to the fifth height. With this design, by controlling the height relationship between the first magnet 922 and the second magnet 923 in the magnet unit 92 and the micromirror chip 2, the first coil 14 can be positioned in a location with a strong magnetic field generated by the first magnet 922, and the second coil 15 can be positioned in a location with a strong magnetic field generated by the second magnet 923; and during rotation around the first torsion beam 8 and the second torsion beam 4, both the first coil 14 and the second coil 15 are subjected to strong magnetic fields.

[0104] In this embodiment, the bottom ends of the first magnet 922 and the second magnet 923 are in contact with the mounting substrate 91. In each magnet unit 92, the core post 921, the first magnet 922, and the second magnet 923 are at the same height; that is, the first and third heights are zero, and the second, fourth, and sixth heights are equal. In this case, the fifth height is 1 to 2 times the second height (or the fourth or sixth height). That is, when the magnet unit 92 is in the sub-region 11 intercalated in the micromirror chip 2, the micromirror chip 2 is at the same height as the magnet unit 92, or the micromirror chip 2 is located in the upper half of the magnet unit 92. For example, the fifth height is 1.1 times, 1.2 times, or 1.25 times the second height (or the fourth or sixth height). For the four magnet units 92 in the magnet assembly 9, the second height (or the fourth or sixth height) can be equal or unequal; however, the relationship between the fifth height and the second height (or the fourth or sixth height) remains unchanged.

[0105] This design allows the first coil 14 to be positioned in a location with a strong magnetic field within the magnetic field generated by the first magnet 922, and the second coil 15 to be positioned in a location with a strong magnetic field within the magnetic field generated by the second magnet 923. Furthermore, during rotation around the first torsion beam 8 and the second torsion beam 4, both the first coil 14 and the second coil 15 experience strong magnetic fields. On the other hand, by limiting the proportion of the magnet unit 92 protruding above the micromirror chip 2, interference with the movement of the moving parts within the micromirror chip 2 is avoided.

[0106] In some embodiments, the second height and the fourth height are different, but both are higher than or equal to the fifth height. This design enables the provision of magnetic fields with different magnetic field strengths for the first coil 14 and the second coil 15, thereby making it suitable for MEMS micromirrors 1 with different requirements for dual-axis drive capability.

[0107] In the magnet unit 92, the iron core column 921 is made of soft magnetic material, which can guide the magnetic field generated by the first magnet 922 and the second magnet 923 and enhance the magnetic field strength while realizing the installation and fixation of the first magnet 922 and the second magnet 923.

[0108] In this embodiment, the iron core post 921 and the mounting substrate 91 are an integral structure made of the same soft magnetic material. This design allows the mounting substrate 91 to also function as an iron core; since the mounting substrate 91 can cover a larger area of ​​the micromirror chip 2 compared to the iron core post 921, it can further enhance the magnetic field strength. Furthermore, it facilitates the connection and fixation of the iron core post 921 and the mounting substrate 91, which helps ensure the reliability of the connection between them.

[0109] In some embodiments, the mounting base 91 has a first mounting groove 911 and a second mounting groove 912 respectively provided at the bottom positions of the first side surface 924 and the second side surface 925 of the iron core column 921. The first magnet 922 and the second magnet 923 are respectively inserted into the first mounting groove 911 and the second mounting groove 912, and the first mounting groove 911 and the second mounting groove 912 are used to install and fix the first magnet 922 and the second magnet 923. By cooperating with the mounting grooves (e.g., the first mounting groove 911 and the second mounting groove 912) and the iron core column 921, the method of fixing and installing the first magnet 922 and the second magnet 923 can be simplified, and the reliability of assembly can be improved.

[0110] In some embodiments, the iron core column 921 and the mounting base plate 91 can be separate structures made of different materials. The two can be connected by adhesive or by mechanical connection such as threaded connectors or interference fits. In this case, the mounting base plate 91 can be made of lighter materials such as plastic to reduce the overall weight.

[0111] In some embodiments, in the two magnet units 92 located on the same side of the first axis O1, the two iron core columns 921 can be a connected integral structure. In this case, the two first side surfaces 924 can also be connected as one side surface, and the two first magnets 922 can also be a connected integral structure. This design simplifies the structure of the magnet units 92 in the magnet assembly 9 and also simplifies the manufacturing process of the magnet assembly 9. For example, the function of two iron core columns 921 can be achieved by processing a single column structure, the two first side surfaces 924 can be formed in one process, and the function of two first magnets 922 can be achieved by attaching a single magnet to the iron core column.

[0112] In this embodiment, the four magnet units 92 in the magnet assembly 9 have a symmetrical structure with respect to the first axis O1 and the second axis O2, but the magnetic pole arrangements of the first magnet 922 and the second magnet 923 are not exactly the same. In the two magnet units 92 located on the same side of the second axis O2 and on opposite sides of the first axis O1, the magnetic poles of the two first magnets 922 near the first coil 14 are different, while the magnetic poles of the two second magnets 923 near the second coil 15 are the same. Similarly, in the two magnet units 92 located on the same side of the first axis O1 and on opposite sides of the second axis O2, the magnetic poles of the two first magnets 922 near the first coil 14 are the same, while the magnetic poles of the two second magnets 923 near the second coil 15 are different.

[0113] For example, such as Figure 9 and Figure 10 As shown, the direction of the first axis O1, i.e., the first direction X, is... Figure 9 and Figure 10 The longitudinal direction of the second axis O2, i.e., the direction of the second direction Y, is... Figure 9 and Figure 10 In the horizontal direction within the coil. For the magnet unit 92 located in the upper left corner, the first magnet 922 is arranged with its S pole near the iron core post 921 and its N pole near the first coil 14, and the second magnet 923 is arranged with its S pole near the iron core post 921 and its N pole near the second coil 15. For the magnet unit 92 located in the upper right corner, the first magnet 922 is arranged with its N pole near the iron core post 921 and its S pole near the first coil 14, and the second magnet 923 is arranged with its S pole near the iron core post 921 and its N pole near the second coil 15.

[0114] For the magnet unit 92 located in the lower left corner, the first magnet 922 is arranged with its S pole near the iron core post 921 and its N pole near the first coil 14, and the second magnet 923 is arranged with its N pole near the iron core post 921 and its S pole near the second coil 15. For the magnet unit 92 located in the lower right corner, the first magnet 922 is arranged with its N pole near the iron core post 921 and its S pole near the first coil 14, and the second magnet 923 is arranged with its N pole near the iron core post 921 and its S pole near the second coil 15.

[0115] The direction and strength of the magnetic field formed by the magnet assembly 9 using the above design are as follows: Figure 9 and Figure 10 As shown, in Figure 9 In the diagram, both the thick and thin arrows indicate the direction of the magnetic field in the area. A thick arrow indicates a stronger magnetic field (e.g., >0.3T), while a thin arrow indicates a weaker magnetic field (e.g., <0.1T or even <0.05T).

[0116] from Figure 9 and Figure 10 As can be seen, the magnetic field generated by the first magnet 922 in different magnet units 92 is concentrated near the first coil 14 at the edge of sub-region 11. On one side of the first axis O1, the magnetic field extends from the two sub-regions 11 toward the first frame 12 in a direction perpendicular to the first coil 14 at the edge of the corresponding sub-region 11; on the other side of the first axis O1, the magnetic field extends from the first frame 12 toward the two sub-regions 11 in a direction perpendicular to the first coil 14 at the edge of the two sub-regions 11. In this magnetic field distribution, after the first coil 14 is energized, the Ampere force on the four parts of the coil at the edge of the four sub-regions 11 can drive the first frame 12 to rotate around the first torsion beam 8, thereby causing the reflector 7 to rotate around the first axis O1.

[0117] from Figure 9 and Figure 10It can also be seen that the magnetic field generated by the second magnet 923 in different magnet units 92 is concentrated near the edge of the second frame portion 131 of the sub-region 11. On one side of the second axis O2, the magnetic field extends from the hollowed-out region 10 inside the second frame 13 in a direction perpendicular to the second coil 15 in the second frame portion 131 to the outside of the second frame 13; on the other side of the second axis O2, the magnetic field extends from the outside of the second frame 13 in a direction perpendicular to the second coil 15 in the second frame portion 131 into the hollowed-out region 10 inside the second frame 13. In addition, although there is also a magnetic field distribution at the position of the third frame portion 132 in the second frame 13, the magnetic field strength is small, and the magnetic field direction is different at different positions in the first direction X, so there is a certain degree of cancellation. In this magnetic field distribution, after the second coil 15 is energized, the Ampere force on the two parts of the coil in the two second frame portions 131 can drive the second frame 13 to rotate around the second torsion beam 4, thereby driving the reflector 7 to rotate around the second axis O2. The Ampere force experienced by the two coils of the second coil 15 located in the two third frame sections 132 is essentially zero.

[0118] As can be seen from the above description, in the MEMS micromirror 1 provided in the embodiments of this application, there is a hollow area 10 between the first frame 12 and the second frame 13 of the micromirror chip 2. The magnet assembly 9 has four magnet units 92 inserted into different parts of the hollow area 10 in the micromirror chip 2. The magnet unit 92 includes an iron core column 921, a first magnet 922 and a second magnet 923. The first magnet 922 and the second magnet 923 are the driving magnets of the first coil 14 and the second coil 15, respectively, and are used to provide magnetic fields for the electromagnetically driven reflector 7 to move around the first axis O1 and the second axis O2.

[0119] This design, on the one hand, utilizes the space inside the micromirror chip 2 by inserting the magnet unit 92 into the hollow area 10, making efficient use of the internal space and resulting in a more compact structure for the MEMS micromirror 1, thus reducing its package size. On the other hand, the design of the magnet unit 92 allows for the separation of the magnetic fields driving the first coil 14 and the second coil 15, facilitating the individual and simultaneous driving of the dual-axis motion of the MEMS micromirror 1 through dual coils, and avoiding mechanical crosstalk between the dual-axis motions, thereby improving the motion control accuracy of the MEMS micromirror 1. On the other hand, by inserting the magnet unit 92 into the hollow area 10 in the micromirror chip 2, the iron core post 921, the first magnet 922 and the second magnet 923 in the magnet unit 92 can all be located inside the micromirror chip 2, and the first magnet 922 can be close to the first coil 14 and the second magnet 923 can be close to the second coil 15. Thus, the strongest magnetic field area of ​​the magnet can be used directly to generate an Ampere force on the coil. Therefore, the driving capability of the MEMS micromirror 1 can be improved, or the volume and weight of the magnet (including the first magnet 922 and the second magnet 923) and the iron core post 921 can be significantly reduced while ensuring the driving capability of the MEMS micromirror 1, which is conducive to achieving miniaturization and weight reduction of the package.

[0120] Furthermore, the magnetic circuit design in the magnet assembly 9 allows the portions of the first coil 14 located at the edges of the four sub-regions 11 to participate in torque provision, improving driving capability and further reducing mechanical crosstalk between dual-axis movements, thereby improving the motion control accuracy of the MEMS micromirror 1.

[0121] This application also provides another MEMS micromirror 1, such as... Figure 11 As shown, the difference between this MEMS micromirror 1 and the MEMS micromirror 1 in the above embodiment is that the two fixing anchor points 3 are located outside the second frame 13, and the third frame portion 132 adopts a concave design at the position of the second axis O2, that is, the second frame 13 includes a concave portion facing the first frame 12 at the position of the second axis O2. The concave portion is connected to the fixing anchor points 3 through the second torsion beam 4. This design allows for a reduction in the size of the micromirror chip 2 while the fixing anchor points 3 are external, thereby facilitating a reduction in the package size of the MEMS micromirror 1.

[0122] In some embodiments, when the MEMS micromirror 1 uses an external fixed anchor point 3, the third frame portion 132 can still be designed to be parallel to the first axis O1. This design reduces the fabrication difficulty of the micromirror chip 2 even with the fixed anchor point 3 externally mounted.

[0123] The MEMS micromirror 1 provided in this embodiment differs from the MEMS micromirror 1 in the above embodiments in that: 1. The first frame 12 is square in shape, and the reflector 7 is also square in shape; 2. Both the first torsion beam 8 and the second torsion beam 4 are straight beams. This application also provides another MEMS micromirror 1, such as... Figure 12 As shown, the MEMS micromirror 1 and Figure 11 The difference in MEMS micromirror 1 is that the top of the first frame 12 has been ground flat. The first torsion beam 8 adopts a serpentine beam, which is beneficial for adjusting the resonant frequency and facilitating wiring.

[0124] It can be seen that the solution provided in this application embodiment can be applied to MEMS micromirrors 1 with different designs.

[0125] In some embodiments, the MEMS micromirror 1 is provided with angle sensors at the root positions of the first torsion beam 8 and the second torsion beam 4, respectively. The angle sensors are used to detect and feedback the torsion angle of the first torsion beam 8 and the second torsion beam 4 when the MEMS micromirror 1 is in operation, thereby facilitating the realization of closed-loop control of the MEMS micromirror 1.

[0126] Angle sensors can employ piezoresistive sensors and Hall effect sensors, among others, to achieve angle monitoring. A piezoresistive sensor comprises four terminals and a piezoresistive strip structure. This strip structure is typically cross-shaped or consists of four strips forming a Wheatstone bridge, with a driving voltage applied to two opposite ports. When the micromirror angle changes, the torsion beam structure twists, causing a change in the positional stress of the piezoresistive strip structure. Due to the piezoresistive effect, the resistance of the piezoresistive strip structure changes, resulting in a change in the voltage between the positive and negative feedback terminals. The difference between these two voltages is the feedback voltage. Ideally, the change in feedback voltage should have a linear relationship with the torsion angle.

[0127] Hall sensors are based on the Hall effect, which occurs when a magnetic field perpendicular to the current direction exists on a current-carrying conductor. Electrons in the conductor are deflected by the Lorentz force and accumulate on one side of the conductor, generating a voltage (Hall voltage). The electric field generated by the Hall effect is perpendicular to both the current and the magnetic field. The force exerted by this electric field on subsequent electrons balances the Lorentz force generated by the magnetic field, allowing subsequent electrons to pass smoothly without being deflected. Therefore, Hall sensors can be used to detect magnetic field strength. Since the magnetic field around the MEMS micromirror 1 is fixed, the position of the Hall sensor can be deduced from the detected magnetic field strength, thus enabling the detection of torsion angles.

[0128] In the above embodiments, the magnet unit 92 is inserted into the sub-region 11 of the micromirror chip 2, and the top heights of the first magnet 922 and the second magnet 923 in the magnet unit 92 are not lower than the micromirror chip 2. However, the MEMS micromirror 1 provided in this application is not limited to this. For example, in some embodiments, the magnet unit 92 is disposed in the mounting substrate 91 at a position opposite to the sub-region 11, and the heights of the first magnet 922, the second magnet 923, and the iron core post 921 in the magnet unit 92 are all lower than the micromirror chip 2. This design, on the one hand, by utilizing the position of the magnet unit 92 in the mounting substrate 91 opposite to the sub-region 11, can make reasonable use of the space in the MEMS micromirror 1, making the structure of the MEMS micromirror 1 more compact, thereby helping to reduce the package size of the MEMS micromirror 1. On the other hand, through the design of the magnet unit 92, the magnetic fields of the driving first coil 14 and the second coil 15 can be separated, which is beneficial for driving the dual-axis motion of the MEMS micromirror 1 individually and simultaneously through the dual coils, and can avoid mechanical crosstalk between the dual-axis motions, thereby improving the motion control accuracy of the MEMS micromirror 1. On the other hand, the first magnet 922 in the magnet unit 92 is located near the first coil 14, and the second magnet 923 is located near the second coil 15, so that the stronger magnetic field region in the magnet can be used to generate Ampere force on the coil. Therefore, the driving capability of MEMS micromirror 1 can be improved, or the volume and weight of the magnet (including the first magnet 922 and the second magnet 923) and the iron core column 921 can be significantly reduced while ensuring the driving capability of MEMS micromirror 1, which is conducive to achieving miniaturization and weight reduction of the package.

[0129] Furthermore, the magnetic circuit design in the magnet assembly 9 allows the portions of the first coil 14 located at the edges of the four sub-regions 11 to participate in torque provision, improving driving capability and further reducing mechanical crosstalk between dual-axis movements, thereby improving the motion control accuracy of the MEMS micromirror 1.

[0130] As described above, the micromirror chip 2 in the MEMS micromirror 1 is a plate-shaped structure formed by processing a semiconductor substrate using semiconductor processing technology. The semiconductor substrate used to fabricate the micromirror chip 2 can be a silicon wafer, silicon-on-insulator (SOI), etc. The following description uses silicon-on-insulator (SOI) as an example to illustrate the fabrication process of the micromirror chip 2.

[0131] like Figure 13 As shown, the fabrication method of the micromirror chip 2 includes:

[0132] Step S1: Provide silicon-on-insulator (SOI). The silicon-on-insulator (SOI) includes a device layer, an insulating layer, and a substrate layer stacked together.

[0133] Step S2: Fabricate a piezoresistive structure using a doping process. This piezoresistive structure is used to provide feedback on the torsion angle.

[0134] Step S3: Fabricate the first metal layer. The first metal layer can be fabricated using methods such as magnetron sputtering. The first metal layer is used to connect the piezoresistive structure and as a jumper for the second metal layer.

[0135] Step S4: Fabricate the second metal layer. The second metal layer is fabricated by methods such as electroplating. This second metal layer is used to fabricate the connecting electrodes on the first coil 14, the second coil 15, and the fixed anchor point 3. An insulating layer exists between the first and second metal layers, and the connection is achieved by drilling holes.

[0136] Step S5: Perform front-side etching. Front-side etching can form structures such as the first frame 12, the first torsion beam 8, the second frame 13, and the second torsion beam 4.

[0137] Step S6: Perform back-side etching. The support structure 73 and other structures are fabricated through back-side etching.

[0138] Step S7: Structure Release. Structure release can be achieved by etching the insulating layer in SOI, thus releasing the movable structure.

[0139] Step S8: Fabrication of the mirror layer. The mirror layer can be formed by evaporation deposition in the first frame 12.

[0140] It should be noted that the above text and accompanying figures only illustrate the basic fabrication process of the micromirror chip 2. For micromirror chips 2 with different structures, only adaptive adjustments need to be made to the above steps.

[0141] The MEMS micromirror 1 provided in this application embodiment can be applied to fields such as laser scanning, optical communication, and digital display. Laser scanning is mainly used in LiDAR, 3D cameras, barcode scanning, laser printers, and medical imaging. Optical communication mainly refers to applications such as optical add-drop multiplexers, optical attenuators, optical switches, and gratings. Digital display refers to applications such as high-definition television, laser micro-projection, digital cinema, automotive head-up displays (HUDs), laser keyboards, and augmented reality (AR).

[0142] Based on this, this application provides a laser device that can include a laser and a MEMS micromirror 1 as described in the above embodiments, wherein the reflector 7 in the MEMS micromirror 1 is used to reflect the laser emitted by the laser.

[0143] For example, the laser device is a lidar, such as... Figure 14As shown, the lidar 100 includes a laser 110, a collimator 120, a MEMS micromirror 1, a receiving optical system 130, and a detector 140. The signal light emitted by the laser 110 is collimated and shaped by the collimator 120 and then illuminates the MEMS micromirror 1. The MEMS micromirror 1 rotates rapidly, scanning and emitting the signal light onto surrounding targets, thus completing the detection of the targets. The signal light is reflected by the targets and then received by the detector 140 through the receiving optical system 130, thereby achieving the purpose of detecting the targets.

[0144] Another example is that the laser device is a laser projection device, such as... Figure 15 As shown, the laser projection device 200 includes a light source 210 and a MEMS micromirror 1. The light source 210 includes a red laser, a green laser, and a blue laser that can emit red, green, and blue light, respectively. The laser beams generated by the red, green, and blue lasers are projected onto the MEMS micromirror 1. The MEMS micromirror 1 twists the scanning beam to the projection position (e.g., a screen), and synchronously modulates the three lasers according to the position of the scanning beam to control the color of a single pixel and generate a projected image.

[0145] This application also provides an optical device, which differs from the laser device described above in that it can use either a laser or other light-emitting devices as the light source. Specifically, the optical device includes a light source and a MEMS micromirror 1 as described in the above embodiments, wherein the reflector 7 in the MEMS micromirror 1 is used to reflect the light beam emitted by the light source.

[0146] This application also provides an optical communication device, which includes an input port, an output port, and a MEMS micromirror 1 as described in the above embodiment; the input port is used to receive optical signals and project the optical signals onto the MEMS micromirror 1; the reflector 7 in the MEMS micromirror 1 is used to reflect the optical signals to the output port. This optical communication device can be an optical switch.

[0147] The technical effects that the optical devices and optical communication devices provided in this application embodiment can achieve are the same as those that the MEMS micromirror 1 in any of the above embodiments can achieve, and will not be repeated here.

[0148] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A micromirror for a microelectromechanical system, characterized in that, The micromirror of the microelectromechanical system includes: A micromirror chip, comprising a reflector, a first frame, a first torsion beam, a second frame, a second torsion beam, and a fixed anchor point; the reflector is disposed on the first frame, the second frame is sleeved on the outside of the first frame, the first frame is connected to the second frame via the first torsion beam, and the second frame is connected to the fixed anchor point via the second torsion beam; a first coil is disposed in the first frame to drive the first frame to rotate around the first torsion beam; a second coil is disposed in the second frame to drive the second frame to rotate around the second torsion beam; a hollow area exists between the first frame and the second frame; and A magnet unit is disposed at a position opposite to the hollowed-out area, and includes a first magnet and a second magnet; the first magnet is the driving magnet of the first coil, and the second magnet is the driving magnet of the second coil.

2. The micromirror for microelectromechanical systems according to claim 1, characterized in that, The axis of the first torsion beam is the first axis, and the axis of the second torsion beam is the second axis; the first axis and the second axis are perpendicular to each other; The first frame includes two first frame portions located on both sides of the first axis, wherein the first frame portions are structures that gradually bulge outward as they move along the first axis toward the second axis; The second frame includes two second frame portions located on both sides of the second axis and parallel to the second axis, and the second frame portions are connected to the first torsion beam.

3. The micromirror for microelectromechanical systems according to claim 2, characterized in that, The hollowed-out area is divided into four sub-areas according to the first axis and the second axis; The micromirror of the microelectromechanical system includes four magnet units, which are respectively disposed at positions opposite to the four sub-regions.

4. The micromirror for microelectromechanical systems according to claim 3, characterized in that, The magnet unit further includes an iron core column, the outer peripheral surface of which includes a first side and a second side. The first side is opposite to the first frame portion at the edge of the sub-region, and the first magnet is attached to the first side. The second side is opposite to the second frame portion at the edge of the sub-region, and the second magnet is attached to the second side.

5. The micromirror for microelectromechanical systems according to claim 4, characterized in that, The first side is parallel to the opposite first coil, and the first magnet is a magnetic sheet that extends from the first side, with two magnetic poles in the magnetic sheet arranged in a direction perpendicular to the first side.

6. The micromirror for microelectromechanical systems according to claim 4 or 5, characterized in that, The second side is parallel to the opposite second coil, and the second magnet is a magnetic sheet that extends from the second side, with two magnetic poles in the magnetic sheet arranged in a direction perpendicular to the second side.

7. The micromirror for microelectromechanical systems according to any one of claims 4 to 6, characterized in that, In the two magnet units located on the same side of the first axis, the two iron core columns are connected to form a single structure, the two first side surfaces are connected to form a single side surface, and the two first magnets are connected to form a single structure.

8. The micromirror for microelectromechanical systems according to any one of claims 4 to 7, characterized in that, The microelectromechanical system micromirror also includes a mounting base, and the iron core column is disposed on the mounting base; Relative to the mounting substrate, the bottom height of the first magnet in the magnet unit is a first height, and the top height is a second height; the bottom height of the second magnet is a third height, and the top height is a fourth height; the height of the micromirror chip is a fifth height. Wherein, both the first height and the third height are lower than the fifth height; The second height and the fourth height are both higher than or equal to the fifth height.

9. The micromirror for microelectromechanical systems according to claim 8, characterized in that, The second height and the fourth height are both higher than or equal to the fifth height, and lower than or equal to twice the fifth height.

10. The micromirror for microelectromechanical systems according to any one of claims 4 to 9, characterized in that, The micromirror of the microelectromechanical system also includes a mounting substrate, on which the iron core column is disposed. The mounting substrate has a mounting groove on the outer side of the bottom of the iron core column, and the first magnet and the second magnet are mounted in the mounting groove.

11. The micromirror for microelectromechanical systems according to any one of claims 4 to 10, characterized in that, The iron core column and the mounting base plate are an integral structure made of soft magnetic material.

12. The micromirror for microelectromechanical systems according to any one of claims 3 to 11, characterized in that, In the two magnet units located on the same side of the second axis, the two first magnets have different magnetic poles near the first coil, and the two second magnets have the same magnetic poles near the second coil; In the two magnet units located on the same side of the first axis, the two first magnets have the same magnetic poles near the first coil, and the two second magnets have different magnetic poles near the second coil.

13. The micromirror for microelectromechanical systems according to any one of claims 2 to 12, characterized in that, The first frame is a rhombus or square with its diagonals coinciding with the first axis and the second axis, or a circle with its center coinciding with the intersection of the first axis and the second axis, or an ellipse with its major axis and minor axis coinciding with the first axis and the second axis, or an ellipse with its major axis and minor axis coinciding with the second axis and the first axis, respectively.

14. The micromirror for microelectromechanical systems according to any one of claims 1 to 13, characterized in that, The first coil is disposed around the reflector in the first frame and extends to the fixed anchor point via the first torsion beam, the second frame, and the second torsion beam.

15. The micromirror for microelectromechanical systems according to any one of claims 1 to 14, characterized in that, The first frame and the reflector are an integral structure, and the outer peripheral edges of the reflector are all connected to the first frame.

16. The micromirror for microelectromechanical systems according to any one of claims 1 to 15, characterized in that, The fixed anchor point is located inside the first frame and within the hollowed-out area.

17. The micromirror for microelectromechanical systems according to any one of claims 1 to 15, characterized in that, The fixed anchor point is located on the outside of the first frame.

18. The micromirror for microelectromechanical systems according to claim 17, characterized in that, The second frame includes a recessed portion that is recessed toward the first frame at the location of the second torsion beam, and the recessed portion is connected to the fixed anchor point via the second torsion beam.

19. The micromirror for microelectromechanical systems according to any one of claims 1 to 18, characterized in that, The first torsion beam is a straight beam, a folded beam, a curved beam, or a serpentine beam; the second torsion beam is a straight beam, a folded beam, a curved beam, or a serpentine beam.

20. The micromirror for microelectromechanical systems according to any one of claims 1 to 19, characterized in that, The micromirror of the microelectromechanical system also includes an angle sensor disposed on the first torsion beam and / or the second torsion beam; The angle sensor is a Hall sensor or a piezoresistive sensor.

21. An optical device, characterized in that, The optical device includes a light source and a microelectromechanical system (MEMS) micromirror as described in any one of claims 1 to 20, wherein a mirror in the MEMS micromirror is used to reflect the light beam emitted by the light source.

22. An optical communication device, characterized in that, The optical communication device includes an input port, an output port, and a microelectromechanical system micromirror as described in any one of claims 1 to 20; The input port is used to receive optical signals and project the optical signals onto the micromirror of the microelectromechanical system. The reflector in the micromirror of the microelectromechanical system is used to reflect the optical signal to the output port.

Images