Membrane mirror and method for manufacturing the same

Abstract

This application provides a MEMS micromirror and its fabrication method, relating to the field of semiconductor device technology. The MEMS micromirror includes: a reflector; a support frame surrounding the outer periphery of the reflector; and a first torsion beam connecting the reflector and the support frame, extending along a first direction, and comprising multiple interlaced beam segments. This MEMS micromirror can improve the structural strength and impact resistance of the first torsion beam connecting the reflector and the support frame, thereby enhancing the reliability and durability of the MEMS micromirror.

Description

Technical Field

[0001] This application relates to the field of semiconductor device technology, and in particular to a MEMS micromirror and its fabrication method. Background Technology

[0002] MEMS (Micro-Electro-Mechanical System) micromirrors are widely used in fields such as laser scanning, optical imaging, augmented reality (AR) and virtual reality (VR) devices, lidar (LiDAR), and medical optical instruments.

[0003] In related technologies, MEMS micromirrors are designed by fixing the micromirror to a frame via a straight cantilever beam. However, this design results in poor stability of the cantilever beam, making it susceptible to external vibrations. When the micromirror is in operation, its deflection causes the cantilever beam to be under constant stress, making it prone to breakage upon external impact, severely affecting the reliability of the electromagnetic micromirror. Summary of the Invention

[0004] This application provides a MEMS micromirror and its fabrication method to improve the structural strength and impact resistance of the first torsion beam connecting the reflector and the support frame, thereby enhancing the reliability and durability of the MEMS micromirror.

[0005] On one hand, this application provides a MEMS micromirror, including: a reflector; a support frame surrounding the outer periphery of the reflector; and a first torsion beam connecting the reflector and the support frame and extending along a first direction, wherein the first torsion beam includes multiple interlocking beam segments.

[0006] In one possible implementation, the topology of the first torsion beam is biomimetic, resembling a spider web.

[0007] In one possible implementation, the first torsion beam includes multiple hexagonal beam segments and multiple straight beam segments, with the hexagonal beam segments arranged sequentially from the inside out, and the straight beam segments extending along the diagonals of the hexagonal beam segments and connecting all the hexagonal beam segments.

[0008] In one possible implementation, at least one of the back surface of the reflector and the back surface of the support frame has reinforcing ribs.

[0009] In one possible implementation, the MEMS micromirror further includes: a base surrounding the periphery of a support frame; and a second torsion beam connecting the support frame and the base and extending along a second direction, wherein the second torsion beam comprises multiple interlocking beam segments.

[0010] In one possible implementation, the topology of the second torsion beam is biomimetic, resembling a spider web.

[0011] On the other hand, this application provides a method for fabricating a MEMS micromirror, comprising:

[0012] Provide substrate;

[0013] A dielectric layer is deposited on the substrate;

[0014] A mask is formed on the dielectric layer, and the mask has multiple first mask openings in the region where the first torsion beam is to be formed;

[0015] The dielectric layer and the substrate are etched along the opening of the first mask to form a reflector, a support frame, and a first torsion beam connecting the reflector and the support frame; wherein the first torsion beam includes multiple interlocking beam segments.

[0016] In one possible implementation, etching is performed along the first mask opening on the dielectric layer and the substrate, including:

[0017] The dielectric layer is etched along the opening of the first mask to form multiple through openings in the dielectric layer;

[0018] The substrate is etched along the opening of the first mask to form a reflector, a support frame, and a first torsion beam.

[0019] In one possible implementation, the substrate includes a first wafer, a second wafer, and a third wafer stacked sequentially, with a dielectric layer formed on the third wafer; etching the substrate includes:

[0020] The third wafer is etched along the opening of the first mask to form the mirror, the support frame, and the first torsion beam.

[0021] In one possible implementation, the manufacturing method further includes:

[0022] The first and second wafers are etched from the side surface of the first wafer facing away from the third wafer to form a reinforcing rib on at least one of the back surface of the mirror and the back surface of the support frame.

[0023] This application provides a MEMS micromirror and its fabrication method. The MEMS micromirror has a first torsion beam connecting a reflector and a support frame. The first torsion beam extends along a first direction to allow the reflector to deflect about the first direction as its rotation axis. By designing the first torsion beam to include multiple interlocking beam segments, dynamic loads are transmitted between the reflector and the support frame through these segments. The dynamic loads can be evenly distributed among the beam segments, reducing local stress concentration in the first torsion beam. This improves the impact resistance of the first torsion beam and prevents it from breaking. Simultaneously, the interlocking design of the multiple beam segments also increases the redundancy of the first torsion beam; even if some beam segments are damaged, the remaining segments can still maintain the reflector's motion function. Therefore, the reliability and durability of the MEMS micromirror are improved. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a process flow diagram of the key steps in the fabrication of MEMS micromirrors in related technologies;

[0026] Figure 2 This is a schematic diagram of a planar structure of a MEMS micromirror in related technologies;

[0027] Figure 3 A schematic diagram of a planar structure of a MEMS micromirror provided in an embodiment of this application;

[0028] Figure 4 for Figure 3 A partial cross-sectional view of the MEMS micromirror taken along line AA;

[0029] Figure 5 for Figure 3 A magnified view of the MEMS micromirror at point A;

[0030] Figure 6 A flowchart illustrating the steps of a method for fabricating a MEMS micromirror provided in an embodiment of this application;

[0031] Figure 7A A schematic diagram of a substrate for fabricating MEMS micromirrors;

[0032] Figure 7B This is a schematic diagram of forming a dielectric layer on a substrate;

[0033] Figure 7CThis is a schematic diagram of forming a mask on a dielectric layer.

[0034] Figure 7D A schematic diagram showing the dielectric layer patterned along the first mask opening in the mask;

[0035] Figure 7E This is a schematic diagram showing the patterning of the substrate along the first mask opening in the mask.

[0036] Figure 7F This is a schematic diagram showing the first wafer and the second wafer from the back side of the first wafer.

[0037] Explanation of reference numerals in the attached figures:

[0038] 100-MEMS micromirror;

[0039] 101-Reflector; 1011-Metal mirror; 102-Support frame; 1021-Drive coil; 103-First torsion beam; 1031-Wire; 104-Base; 105-Second torsion beam; 106-Back cavity;

[0040] 110 - Substrate; 111 - First wafer; 112 - Second wafer; 113 - Third wafer; 1131 - Active region; 114 - Barrier layer; 115 - Hard mask layer; 1151 - Second mask opening;

[0041] 120 - Insulation layer;

[0042] 130 - Electrode layer;

[0043] 140 - Dielectric layer; 141 - Window; 142 - Through opening;

[0044] 150 - Mask; 151 - First mask opening;

[0045] a - Beam segment; a1 - Hexagonal beam segment; a2 - Straight beam segment;

[0046] b-Reinforcing rib. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Figure 1 This is a process flow diagram illustrating the key steps in fabricating MEMS micromirrors in related technologies. (Refer to...) Figure 1 As shown in (a), a key step in fabricating the MEMS micromirror is to form the first cantilever beam 13 connecting the micromirror 11 and the frame 12 through an etching process. (Refer to...) Figure 1 As shown in (b), the back side of the substrate 10 is finally etched to form a suspended micromirror 11 and a first cantilever beam 13, and reinforcing ribs 14 are formed on the back side of the micromirror 11 and the back side of the frame 12.

[0049] Figure 2 This is a schematic diagram of a planar structure of a MEMS micromirror in related technologies. Combined with... Figure 1 and Figure 2 As shown, in related technologies, the first cantilever beam 13 formed between the micromirror 11 and the frame 12 by an etching process is typically a monolithic straight beam. That is, the micromirror 11 and the frame 12 are connected by a straight first cantilever beam 13.

[0050] However, the linear first cantilever beam 13 has poor load-bearing capacity, especially during the mechanical movement of the micromirror 11's deflection. The first cantilever beam 13 is subjected to repeated dynamic loads over a long period, leading to the initiation of fatigue cracks. Furthermore, when subjected to external impacts (such as vibration, collision, or drops), the first cantilever beam 13 is prone to fracture, causing the entire MEMS micromirror to fail. This severely impacts the reliability and durability of the MEMS micromirror.

[0051] in addition, Figure 2 Taking an electromagnetic MEMS micromirror as an example, the MEMS micromirror is surrounded by a support base 15 outside the frame 12. The frame 12 and the support base 15 are connected by a second cantilever beam 16. The extension direction of the second cantilever beam 16 is perpendicular to the extension direction of the first cantilever beam 13. In this case, the second cantilever beam 16 can also be formed by etching the first cantilever beam 13 as described above, and the second cantilever beam 16 can also be an integral straight beam. Similar to the first cantilever beam 13, the second cantilever beam 16 is also prone to breakage under impact, causing the MEMS micromirror to fail.

[0052] In view of this, embodiments of this application provide a MEMS micromirror and its fabrication method. The MEMS micromirror has a first torsion beam connected between a reflector and a support frame. The first torsion beam extends along a first direction to allow the reflector to deflect about the first direction as its rotation axis. By designing the first torsion beam to include multiple interlocking beam segments, dynamic loads are transmitted between the reflector and the support frame through these segments. The dynamic loads can be evenly distributed among the beam segments, reducing local stress concentration in the first torsion beam. This improves the impact resistance of the first torsion beam and prevents it from breaking. Simultaneously, the interlocking design of the multiple beam segments also increases the redundancy of the first torsion beam; even if some beam segments are damaged, the remaining segments can still maintain the reflector's motion function. Therefore, the reliability and durability of the MEMS micromirror are improved.

[0053] The MEMS micromirrors and their fabrication methods provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0054] Figure 3 This is a schematic diagram of a planar structure of a MEMS micromirror provided in an embodiment of this application. (Refer to...) Figure 3 As shown in the figure, this application embodiment provides a MEMS micromirror 100, which includes a reflector 101, a support frame 102, and a first torsion beam 103. The reflector 101 is the core component of the MEMS micromirror 100, used to reflect light and realize the scanning or guiding function of light. The support frame 102 surrounds the outer periphery of the reflector 101 and is the connection basis of the reflector 101. The first torsion beam 103 connects the reflector 101 and the support frame 102. One end of the first torsion beam 103 is connected to the edge of the reflector 101, and the other end of the first torsion beam 103 is connected to the inner wall of the support frame 102.

[0055] The first torsion beam 103 extends along a first direction and can be disposed on opposite sides of the reflector 101, with both sides of the first torsion beam 103 located on the same straight line extending along the first direction. The first torsion beam 103 can serve as the rotation axis of the reflector 101, and can torsion during the operation of the MEMS micromirror 100. This allows the reflector 101 to deflect about the first direction as its rotation axis, or it can be considered that the reflector 101 deflects around the first torsion beam 103.

[0056] Based on this, the reflector 101 can also use a second direction perpendicular to the first direction as its rotation axis, allowing the reflector 101 to rotate around the second direction. This application embodiment uses... Figure 3Taking the paper orientation as an example, the first direction can be the Y-axis direction, and the second direction can be the X-axis direction. Therefore, the reflector 101 can rotate both around the Y-axis and around the X-axis direction, and the reflector 101 can achieve two-dimensional deflection, meeting the omnidirectional scanning requirements of the MEMS micromirror 100.

[0057] like Figure 3 As shown, in one embodiment, the MEMS micromirror 100 may further include a base 104, which surrounds the outer periphery of the support frame 102. Figure 3 Only the outline of the base 104 is shown, not its complete structure. A second torsion beam 105 connects the base 104 and the support frame 102, and the second torsion beam 105 is generally along a second direction ( Figure 3 (as shown in the X direction). The second torsion beam 105 can be disposed on opposite sides of the support frame 102, with the second torsion beams 105 on both sides located on the same straight line extending along the second direction.

[0058] During the operation of the MEMS micromirror 100, the second torsion beam 105 can also be torn. As a rotation axis extending along the second direction, the second torsion beam 105 drives the support frame 102, along with the reflector 101, to deflect around the second direction. Thus, through the cooperation of the first torsion beam 103 and the second torsion beam 105, the reflector 101 achieves two-dimensional deflection around the X-axis and Y-axis.

[0059] Figure 3 The MEMS micromirror 100 shown can be an electromagnetic MEMS micromirror 100, specifically designed based on the Lorentz force principle. It utilizes the electromagnetic force generated by the MEMS micromirror 100 under the influence of a magnetic field to drive the deflector 101. For example, a drive coil 1021 can be provided on the support frame 102, and a permanent magnet can be mounted on the reflector 101, or a soft magnetic thin film layer (e.g., nickel or nickel-iron alloy) can be integrated on the back of the reflector 101. The permanent magnet or soft magnetic thin film layer, or the current-carrying drive coil 1021, interact to generate a Lorentz force, thereby driving the reflector 101 to deflect.

[0060] In other embodiments, the reflector 101 can also rotate around the second direction in other ways. For example, a piezoelectric ceramic block can be connected to the support frame 102, and by passing an electric current through the piezoelectric ceramic block, the piezoelectric ceramic block is deformed, thereby causing the reflector 101 to deflect around the second direction. This application does not impose specific limitations on this.

[0061] Figure 4 for Figure 3 A partial cross-sectional view of the MEMS micromirror taken along line AA. Figure 4 The main points are shown in the middle. Figure 3The diagram shows the hierarchical structure of the MEMS micromirror 100. Furthermore, to more clearly illustrate the hierarchical structure of the MEMS micromirror 100, Figure 4 The diagram only shows the reflector 101, the support frame 102, and the first torsion beam 103 connecting the reflector 101 and the support frame 102.

[0062] Combination Figure 3 and Figure 4 As shown in the embodiment of this application, the first torsion beam 103 includes multiple beam segments a, which are connected in an interlaced manner. By setting multiple interlaced and connected beam segments a instead of a single straight cantilever beam, the dynamic load on the first torsion beam 103 (including the torsional load of the first torsion beam 103 itself and the load transmitted from the outside world, such as collisions and shaking, to the MEMS micromirror 100) can be evenly distributed to each beam segment a.

[0063] This significantly reduces local stress concentration in the first torsion beam 103, achieving a balance between high strength and flexibility, improving its impact resistance, and preventing breakage. Simultaneously, the design of multiple beam segments a increases the overall redundancy of the first torsion beam 103. Even if some beam segments a are damaged, the remaining segments a can still maintain the torsional deformation capacity of the first torsion beam 103, ensuring that the reflector 101 can deflect normally.

[0064] It should be noted that, Figure 4 The diagram illustrates the cross-sectional structure of the MEMS micromirror 100 along line AA. In the diagram, one can see that the first torsion beam 103 is located on part of the beam segment a on the cross-sectional plane. These beam segments a are arranged side by side at intervals. Figure 4 The diagram only shows the cross-sectional structure of the first torsion beam 103, while the first torsion beam 103 as a whole is composed of multiple intersecting and connected beam segments a.

[0065] Continue to refer to Figure 4 When the MEMS micromirror 100 is driven by an electromagnetic method, the MEMS micromirror 100 may also include the aforementioned drive coil 1021, which is disposed in the support frame 102. When an external drive signal (such as current or voltage) is applied to the drive coil 1021, the magnetic field generated by the drive coil 1021 interacts with the magnetic material (such as the aforementioned permanent magnet or soft magnetic thin film layer) disposed on the reflector 101, driving the reflector 101 to deflect around the first torsion beam 103, and the first torsion beam 103 torsion accordingly.

[0066] The MEMS micromirror 100 can be fabricated using semiconductor processes, with a support frame 102 and a reflector 101 formed through deposition and etching. Furthermore, a driving coil 1021 can be formed within the support frame 102. Before forming the driving coil 1021, an electrode layer 130 can be formed within the support frame 102. The electrode layer 130 leads out the active region 1131 in the support frame 102, enabling the driving coil 1021 to conduct through the active region 1131 in the support frame 102, thereby allowing current to be passed into the driving coil 1021.

[0067] Continue to refer to Figure 4 Along the thickness direction of the MEMS micromirror 100 (Z direction shown in the figure), the overall thickness of the support frame 102 can be relatively large. This ensures that the support frame 102 has sufficient structural strength to meet the reliability requirements of the MEMS micromirror 100. Sufficient space can also be reserved in the thickness direction of the support frame 102 to facilitate the connection and integration of the support frame 102 with other components or structures.

[0068] Based on this, the back surface of the MEMS micromirror 100 can have a back cavity 106. The back cavity 106 forms a groove on the back surface of the MEMS micromirror 100, and occupies the entire back surface area of ​​the reflector 101 and part of the back surface area of ​​the support frame 102. The back cavity 106 forms a cavity structure on the back surface of the MEMS micromirror 100, realizing the suspended design of the reflector 101 and the first torsion beam 103, and also reserving space for the deflection of the reflector 101.

[0069] The back cavity 106 reduces the thickness of the MEMS micromirror 100 in the middle region of the planar direction, which may have a certain impact on the overall stress performance of the MEMS micromirror 100. For example... Figure 4 As shown, in order to enhance the structural strength of the MEMS micromirror 100, at least one of the back surface of the reflector 101 and the back surface of the support frame 102 may be provided with a reinforcing rib b. The reinforcing rib b is located in the back cavity 106 and protrudes from the back surface of the MEMS micromirror 100.

[0070] The design of the reinforcing rib b can improve the structural strength of the MEMS micromirror 100 and enhance its stress performance. Specifically, placing the reinforcing rib b on the back of the reflector 101 can improve the reliability of the reflector 101 without affecting its suspended state, resulting in smoother movement and better performance. Placing the reinforcing rib b on the back of the support frame 102 can enhance the structural strength of the portion of the support frame 102 near the reflector 101, improving the load-bearing capacity of the support frame 102 for the reflector 101 and resulting in a stronger connection between the reflector 101 and the support frame 102.

[0071] Both the reinforcing rib b on the back of the reflector 101 and the reinforcing rib b on the back of the support frame 102 can share the stress of the first torsion beam 103 during the transmission of dynamic loads between the reflector 101 and the support frame 102 via the first torsion beam 103. This results in less stress on the first torsion beam 103 and higher reliability. It also better prevents crack propagation in the first torsion beam 103 and avoids its fracture.

[0072] like Figure 4 As shown, reinforcing ribs b can be provided on the back of both the reflector 101 and the support frame 102, which plays a better role in improving the overall structural strength of the MEMS micromirror 100. In other examples, reinforcing ribs b can be provided only on the back of the reflector 101, or only on the back of the support frame 102. This application embodiment does not limit this.

[0073] Furthermore, the back surface of the MEMS micromirror 100 may lack reinforcing ribs b in the region where the first torsion beam 103 is located, thus maintaining the thinness of the first torsion beam 103. In this way, the first torsion beam 103 can possess good elastic properties, ensuring its ability to undergo torsional deformation and guaranteeing the smooth deflection of the reflector 101.

[0074] Figure 5 for Figure 3 The magnified view of the MEMS micromirror at point A. (Refer to...) Figure 5 As shown, regarding the specific structure of the first torsion beam 103, its topological structure on the plane can be biomimetic spider web-like. The biomimetic spider web-like first torsion beam 103 may include multiple beam segments a extending circumferentially and arranged sequentially inside and outside, as well as multiple beam segments a extending approximately radially and intersecting each other. The radially extending beam segments a intersect with each circumferentially extending beam segment a to form nodes.

[0075] In this way, the dynamic loads applied to the first torsion beam 103, as well as the dynamic loads transmitted to the first torsion beam 103 from the outside, can be transmitted along each beam segment a of the first torsion beam 103 and evenly distributed to multiple nodes. This significantly reduces local stress concentration, improves the impact resistance of the first torsion beam 103, and can prevent the first torsion beam 103 from breaking. Furthermore, the biomimetic spider web-like first torsion beam 103 has better elastic properties, and its ability to withstand torsional loads is also stronger, which can improve the reliability and durability of the first torsion beam 103.

[0076] like Figure 5As shown, based on the biomimetic spider web-like topological structure of the first torsion beam 103, as a collective implementation, the shape of the beam segment a extending circumferentially in the first torsion beam 103 can be hexagonal, and the beam segment a extending approximately radially can extend in a straight line. That is, the first torsion beam 103 includes multiple hexagonal beam segments a1 and multiple straight beam segments a2 arranged sequentially inside and outside. These straight beam segments a2 can extend along the diagonals of each hexagonal beam segment a1 and connect all the hexagonal beam segments a1.

[0077] With this configuration, the first torsion beam 103 has a hexagonal shape, which provides good structural symmetry, enabling more even load distribution and improving its impact resistance, thus enhancing its fracture resistance. Furthermore, the regular shape of the first torsion beam 103 facilitates its structural design and fabrication, improving the overall manufacturing efficiency of the MEMS micromirror 100 and reducing its overall manufacturing cost.

[0078] Will Figure 5 Combined to Figure 3 When the MEMS micromirror 100 also includes a second torsion beam 105, the second torsion beam 105 can also include multiple interlaced beam segments a. In this way, the second torsion beam 105 can evenly distribute its own torsional load and externally transmitted loads to each beam segment a, significantly reducing local stress concentration. While improving the structural strength of the second torsion beam 105, it also enhances its flexibility, improves its impact resistance, and prevents fracture. Simultaneously, it increases the overall redundancy of the second torsion beam 105; even if some beam segments a are damaged, the remaining beam segments a can still maintain the motion function of the second torsion beam 105.

[0079] Similar to the first torsion beam 103, the topological structure of the second torsion beam 105 in the planar direction of the MEMS micromirror 100 can be biomimetic spider web-like. For example, the second torsion beam 105 also includes multiple hexagonal beam segments a1 arranged sequentially from the inside out, and multiple straight beam segments a2 extending along the diagonals of the hexagonal beam segments a1 and connecting all the hexagonal beam segments a1. Further details will not be elaborated here.

[0080] This application also provides a method for fabricating a MEMS micromirror 100, which is used to fabricate the aforementioned MEMS micromirror 100.

[0081] Figure 6 A flowchart illustrating the steps of a method for fabricating a MEMS micromirror provided in an embodiment of this application. Figures 7A-7F A process flow diagram illustrating the fabrication method of the MEMS micromirror 100 provided in this embodiment of the application.

[0082] Reference Figure 6 As shown, the manufacturing method includes the following steps:

[0083] S100. Provides a substrate.

[0084] Figure 7A This diagram illustrates a substrate for fabricating MEMS micromirrors. (Refer to...) Figure 7A As shown, when fabricating the MEMS micromirror 100, a substrate 110 is first provided as a basic support structure for deposition, etching and other processes to be performed on the substrate 110, and finally the MEMS micromirror 100 is formed.

[0085] In some embodiments, the substrate 110 may include a first wafer 111, a second wafer 112, and a third wafer 113 stacked sequentially. The first wafer 111 can serve as a substrate wafer, primarily providing mechanical support. The second wafer 112 can serve as an intermediate wafer, and can be oxidized to form a silicon oxide layer, primarily serving an insulating function. The third wafer 113 can serve as a device wafer, being the functional layer that actually carries the device. The aforementioned structures and devices, such as the reflector 101, drive coil 1021, and electrode layer 130, can be fabricated on the third wafer 113.

[0086] A barrier layer 114 may be formed between the second wafer 112 and the third wafer 113. This barrier layer 114 serves to stop the etching process during the subsequent etching of the first wafer 111, the second wafer 112, and the third wafer 113.

[0087] Continue to refer to Figure 7A Before fabricating structures and devices such as the reflector 101 and the drive coil 1021 on the substrate 110, an electrode layer 130 can be formed on the substrate 110. Specifically, an ion implantation (IMP) process can be performed on the substrate 110, specifically on the third wafer 113, to form an active region 1131 in the substrate 110. Then, the electrode layer 130 is deposited on the substrate 110 to bring out the active region 1131.

[0088] Before forming the electrode layer 130 on the substrate 110, an insulating layer 120 can be deposited on the upper surface of the substrate 110, i.e., the surface of the third wafer 113. This insulating layer 120 is, for example, a silicon nitride layer, a silicon oxide layer, or a composite layer of silicon nitride and silicon oxide. Next, an electrode material layer is deposited on the insulating layer 120. The electrode material layer is made of a metal such as copper, aluminum, silver, or gold. This electrode material layer fills the vias (not shown) formed in the insulating layer 120. These vias correspond to the active regions 1131 in the substrate 110, thus connecting the electrode material layer to the active regions 1131. Then, the electrode material layer is etched using an etching process to pattern it into the desired electrode layer 130.

[0089] S200. A dielectric layer is deposited on the substrate.

[0090] Figure 7B This is a schematic diagram of forming a dielectric layer on a substrate. (Refer to...) Figure 7B As shown, after the electrode layer 130 is formed on the substrate 110, a dielectric layer 140 can be deposited and formed on the substrate 110. The dielectric material of the dielectric layer 140 is, for example, silicon dioxide. The dielectric layer 140 can be formed on the electrode layer 130, and the dielectric layer 140 covers the electrode layer 130 and the insulating layer 120 below the electrode layer 130. The dielectric layer 140 is part of the structure of the first torsion beam 103, and the first torsion beam 103 is subsequently formed by etching the dielectric layer 140 and the substrate 110.

[0091] like Figure 7B As shown, after the dielectric layer 140 is formed on the substrate 110, the metal mirror 1011 of the drive coil 1021 and the reflector 101 can be fabricated next.

[0092] The reflector 101 can be directly formed on the substrate 110, and the metal mirror 1011 can be directly formed on the surface of the substrate 110, such as the third wafer 113. To this end, depositing the dielectric layer 140 on the substrate 110 can include: first depositing a solid dielectric material layer on the substrate 110, and then performing an etching process on the dielectric material layer to pattern it into the dielectric layer 140. The dielectric layer 140 has a window 141 in the area where the reflector 101 is to be formed, and the surface of the substrate 110, such as the third wafer 113, is exposed within the window 141. Subsequently, the metal mirror 1011 of the reflector 101 is deposited within the window 141, and the metal material of the metal mirror 1011 can be aluminum or gold.

[0093] To form the drive coil 1021 on the dielectric layer 140, a coil material layer can first be deposited on the dielectric layer 140. Vias can be formed in the dielectric layer 140, extending through the dielectric layer 140 and reaching the surface of the electrode layer 130. The coil material layer fills the vias to achieve electrical conductivity with the electrode layer 130. Subsequently, an etching process is performed on the coil material layer to pattern it into the drive coil 1021.

[0094] In addition, such as Figure 7B As shown, in some examples, while forming the drive coil 1021 on the dielectric layer 140, a conductor 1031 can be formed in the region on the dielectric layer 140 where the first torsion beam 103 is to be formed. The conductor 1031 can be formed by patterning the material in the region of the coil material layer where the first torsion beam 103 is to be formed, simultaneously with patterning the coil material layer into the drive coil 1021.

[0095] S300. A mask is formed on the dielectric layer, the mask having a plurality of first mask openings in the region where the first torsion beam is to be formed.

[0096] After depositing a dielectric layer 140 on the substrate 110 and fabricating a metal mirror 1011 that forms the drive coil 1021 and the reflector 101, the process of fabricating the first torsion beam 103 and the complete reflector 101 begins.

[0097] Figure 7C This is a schematic diagram of forming a mask on a dielectric layer. (Refer to...) Figure 7C As shown, after entering the process of preparing the first torsion beam 103 and the complete reflector 101, the first step is to form a mask 150 on the dielectric layer 140. The mask 150 covers the dielectric layer 140, the driving coil 1021 and the wire 1031 formed on the dielectric layer 140, and the metal mirror 1011. The mask 150 is, for example, a photoresist layer.

[0098] The mask 150 has first mask openings 151 distributed thereon, which are used for subsequent patterning of the dielectric layer 140 and the substrate 110. The first mask openings 151 distributed in the mask 150 include a plurality of first mask openings 151 located in the region where the first torsion beam 103 is to be formed.

[0099] S400. The dielectric layer and the substrate are etched along the opening of the first mask to form a reflector, a support frame, and a first torsion beam connecting the reflector and the support frame; wherein the first torsion beam includes multiple interlocking beam segments.

[0100] Subsequently, the dielectric layer 140 and the substrate 110 are patterned by etching along the first mask opening 151 on the mask plate 150 to form a reflector 101, a support frame 102, and a first torsion beam 103 connecting the reflector 101 and the support frame 102.

[0101] Figure 7D This is a schematic diagram illustrating the dielectric layer along the first mask opening in the mask. (Refer to...) Figure 7D As shown, since the dielectric layer 140 and the substrate 110 are made of different materials, when etching the dielectric layer 140 and the substrate 110 along the first mask opening 151 on the mask 150, the dielectric layer 140 can be etched first along the first mask opening 151 to form a plurality of through openings 142 in the dielectric layer 140, and the etching stops at the surface of the substrate 110, for example, the third wafer 113. Thus, the portion of the first torsion beam 103 composed of the dielectric layer 140 is formed.

[0102] Figure 7E This is a schematic diagram showing the patterning of a substrate along the first mask opening in the mask. (Refer to...) Figure 7E As shown, after the dielectric layer 140 is patterned along the first mask opening 151 in the mask 150, the substrate 110 is then etched along the first mask opening 151 in the mask 150. Specifically, the third wafer 113 located on the uppermost layer of the substrate 110 is etched to pattern the substrate 110, thereby forming the reflector 101, the support frame 102, and the first torsion beam 103.

[0103] Specifically, by designing multiple first mask openings 151 in the region corresponding to the first torsion beam 103 in the mask plate 150, these multiple first mask openings 151 are transferred into multiple through openings 142 in the dielectric layer 140 during the etching process. Ultimately, a first torsion beam 103 with multiple beam segments a can be formed. Furthermore, by designing the first mask openings 151 in the region where the first torsion beam 103 is located, the multiple beam segments a of the first torsion beam 103 can be made to interweave and connect with each other.

[0104] For example, the mask 150 can be designed in a biomimetic spider web shape in the area corresponding to the first torsion beam 103, with the through openings 142 distributed in the hollow areas of the biomimetic spider web, so that the topological structure of the first torsion beam 103 is in the shape of a biomimetic spider web. For example, the mask 150 is hexagonal in the area corresponding to the first torsion beam 103, so that the formed first torsion beam 103 includes multiple hexagonal beam segments a1 arranged sequentially from the inside to the outside, and multiple straight beam segments a2 extending along the diagonal of the hexagonal beam segments a1 and connecting all the hexagonal beam segments a1.

[0105] Furthermore, as mentioned earlier, by forming a barrier layer 114 between the third wafer 113 and the second wafer 112, the barrier layer 114 acts as a barrier to prevent etching during the etching process of the third wafer 113. This stops the etching process at the barrier layer 114, preventing over-etching of the second wafer 112. In this way, it is ensured that the reflector 101, the support frame 102, and the first torsion beam 103 are all formed on the third wafer 113.

[0106] Figure 7F This is a schematic diagram showing the first and second wafers patterned from the back side of the first wafer. (Refer to...) Figure 7F As shown, after the reflector 101, support frame 102, and first torsion beam 103 are fabricated in the third wafer 113, the back cavity 106 is finally etched on the back side of the MEMS micromirror 100. Specifically, the first wafer 111 and the second wafer 112 are etched from the surface of the first wafer 111 facing away from the third wafer 113, and the etching process stops at the third wafer 113 to form the back cavity 106 on the back side of the MEMS micromirror 100.

[0107] Thus, the complete reflector 101 and the first torsion beam 103 are formed, enabling the reflector 101 and the first torsion beam 103 to be suspended on the support frame 102.

[0108] like Figure 7F As shown, a hard mask layer 115 can be formed between the first wafer 111 and the second wafer 112, and second mask openings 1151 are distributed in the hard mask layer 115. When the etching process reaches the second wafer 112, the second wafer 112 can be etched along the second mask openings 1151 on the second mask plate 150. Material in a portion of the second wafer 112 located within the back cavity 106 is retained to form reinforcing ribs b on at least one of the back surfaces of the reflector 101 and the support frame 102.

[0109] As previously mentioned, by forming a barrier layer 114 between the second wafer 112 and the third wafer 113, the barrier layer 114 acts as a barrier to prevent etching during the etching process of the first wafer 111 and the second wafer 112. This stops the etching process at the barrier layer 114, preventing over-etching of the third wafer 113. Thus, the integrity of the structures and devices formed on the third wafer 113 is ensured.

[0110] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A MEMS micromirror, characterized in that, include: Reflector; A support frame, the support frame being disposed around the outer periphery of the reflector; A first torsion beam is connected between the reflector and the support frame and extends along a first direction, and the first torsion beam comprises multiple interlocking beam segments.

2. The MEMS micromirror according to claim 1, characterized in that, The topology of the first torsion beam is biomimetic spider web-like.

3. The MEMS micromirror according to claim 2, characterized in that, The first torsion beam includes multiple hexagonal beam segments and multiple straight beam segments. The hexagonal beam segments are arranged sequentially from the inside to the outside, and the straight beam segments extend along the diagonals of the hexagonal beam segments and connect all the hexagonal beam segments.

4. The MEMS micromirror according to any one of claims 1-3, characterized in that, At least one of the back surface of the reflector and the back surface of the support frame has reinforcing ribs.

5. The MEMS micromirror according to any one of claims 1-3, characterized in that, Also includes: A base, which surrounds the outer periphery of the support frame; A second torsion beam is connected between the support frame and the base and extends along a second direction, and the second torsion beam comprises multiple interlocking beam segments.

6. The MEMS micromirror according to claim 5, characterized in that, The topology of the second torsion beam is biomimetic spider web-like.

7. A method for fabricating a MEMS micromirror, characterized in that, include: Provide substrate; A dielectric layer is deposited on the substrate; A mask is formed on the dielectric layer, the mask having a plurality of first mask openings in the region where the first torsion beam is to be formed; The dielectric layer and the substrate are etched along the opening of the first mask to form a reflector, a support frame, and a first torsion beam connecting the reflector and the support frame; wherein the first torsion beam comprises multiple interlocking beam segments.

8. The method for fabricating a MEMS micromirror according to claim 7, characterized in that, Etching the dielectric layer and the substrate along the opening of the first mask includes: The dielectric layer is etched along the opening of the first mask to form a plurality of through openings in the dielectric layer; The substrate is etched along the opening of the first mask to form the reflector, the support frame, and the first torsion beam.

9. The method for fabricating a MEMS micromirror according to claim 7, characterized in that, The substrate includes a first wafer, a second wafer, and a third wafer stacked sequentially, and the dielectric layer is formed on the third wafer; Etching the substrate includes: The third wafer is etched along the opening of the first mask to form the reflector, the support frame, and the first torsion beam.

10. The method for fabricating a MEMS micromirror according to claim 9, characterized in that, Also includes: The first wafer and the second wafer are etched from the side surface of the first wafer facing away from the third wafer to form a reinforcing rib on at least one of the back surface of the reflector and the back surface of the support frame.

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