Membrane-based microelectromechanical system (MEMS) devices and methods of making

Abstract

This application provides a MEMS device and its fabrication method. The MEMS device includes a substrate, and a first electrode layer and a second electrode layer stacked on the substrate. The second electrode layer includes an anchor point and a crossbeam connected together. The anchor point is supported between at least one end of the crossbeam and the first electrode layer, and the middle portion of the crossbeam is suspended above the first electrode layer. The anchor point includes a first anchoring portion and a second anchoring portion, which are spaced apart and respectively fixed to opposite sides of the end of the crossbeam. The MEMS device provided by this application has the advantage of preventing the crossbeam from bending due to temperature changes, which is beneficial to improving the performance of the MEMS device.

Description

Technical Field

[0001] This application relates to the field of microelectronics technology, specifically to a MEMS device and its fabrication method. Background Technology

[0002] MEMS (Micro-Electro-Mechanical Systems) is an industrial technology that integrates microelectronics and mechanical engineering. MEMS devices are mechanically movable structures fabricated using MEMS technology. As a type of MEMS device, MEMS resonators achieve frequency-selective filtering of electrical signals through electromechanical coupling. MEMS resonators have the following advantages: small size, low power consumption, shock resistance, compatibility with microelectronic integrated circuit processes, ease of system integration, stable performance, high reliability, and operating frequencies concentrated in the radio frequency band, reaching up to the GHz level, with a high quality factor.

[0003] For electrostatic capacitive MEMS resonators, there are currently two main fabrication processes. One is a bulk silicon deep etching process using an SOI substrate, with the top silicon layer as the structural layer of the resonator. Its advantages are no film layer stress and no frequency drift in the resonant structure, but the device fabrication cost is relatively high. The other approach is a planar process using multiple thin film deposition and etching, with the deposited polycrystalline silicon thin film as the structural layer. The advantages of this approach are compatibility with CMOS processes and relatively low cost. However, because the stress of the polycrystalline silicon thin film itself is difficult to control, the device resonant frequency will drift when the process repeatability is poor. More importantly, the internal stress of the resonant structure will also change with the external ambient temperature, thus causing frequency drift. Summary of the Invention

[0004] To address the issue of internal stress in the aforementioned resonant structure varying with changes in ambient temperature, this application provides a MEMS device and its fabrication method.

[0005] According to a first aspect of the embodiments of this application, a MEMS device is provided, including a substrate, and a first electrode layer and a second electrode layer stacked on the substrate, wherein: the second electrode layer includes an anchor point and a crossbeam connected together, the anchor point being supported between at least one end of the crossbeam and the first electrode layer, and the middle portion of the crossbeam being suspended above the first electrode layer; the anchor point includes a first anchoring portion and a second anchoring portion, the first anchoring portion and the second anchoring portion being spaced apart and respectively fixed to opposite sides of the end of the crossbeam.

[0006] In one possible implementation, the first anchoring portion has a first width, the second anchoring portion has a second width, and the sum of the first width and the second width is 10% to 50% of the width of the end of the beam.

[0007] In one possible implementation, the beam has a plane of symmetry, and the first anchor portion and the second anchor portion are symmetrical about the plane of symmetry of the beam.

[0008] In one possible implementation, the end face of the first anchor portion away from the second anchor portion is flush with the end face of the end of the beam; and / or, the end face of the second anchor portion away from the first anchor portion is flush with the end face of the end of the beam.

[0009] In one possible implementation, there are multiple first anchoring portions and multiple second anchoring portions, with the multiple first anchoring portions arranged at intervals along the extension direction of the crossbeam, and the multiple second anchoring portions arranged at intervals along the extension direction of the crossbeam.

[0010] A second aspect of this application provides a method for fabricating a MEMS device, comprising:

[0011] A first electrode layer is formed on the substrate, and the first electrode layer is etched to form a first groove penetrating the first electrode layer;

[0012] A sacrificial layer is formed on the first electrode layer and within the first groove, and the sacrificial layer is etched to form a second groove, the second groove exposing the corresponding first electrode layer;

[0013] A second electrode layer is formed on the sacrificial layer and the first electrode layer, and the second electrode layer is etched to expose a portion of the sacrificial layer; the etched second electrode layer includes stacked anchor points and crossbeams, the anchor points fill the second groove and are fixed to at least one end of the crossbeams; the anchor points include a first anchoring portion and a second anchoring portion, the first anchoring portion and the second anchoring portion are spaced apart and respectively fixed to opposite sides of the end of the crossbeams;

[0014] Remove the sacrificial layer to release the crossbeam.

[0015] In one possible implementation, the first anchoring portion has a first width, the second anchoring portion has a second width, and the sum of the first width and the second width is 10% to 50% of the width of the end of the beam.

[0016] In one possible implementation, the beam has a plane of symmetry, and the first anchor portion and the second anchor portion are symmetrical about the plane of symmetry of the beam.

[0017] In one possible implementation, the end face of the first anchor portion away from the second anchor portion is flush with the end face of the end of the beam; and / or, the end face of the second anchor portion away from the first anchor portion is flush with the end face of the end of the beam.

[0018] In one possible implementation, there are multiple first anchoring portions and multiple second anchoring portions, with the multiple first anchoring portions arranged at intervals along the extension direction of the crossbeam, and the multiple second anchoring portions arranged at intervals along the extension direction of the crossbeam.

[0019] By using the MEMS device provided in this application embodiment, and by optimizing the anchor point structure and position connecting the two electrodes, and setting the anchor points at intervals and fixing them to opposite sides of the end of the crossbeam, significant deformation of the crossbeam during temperature changes can be effectively avoided, thereby improving the performance of the MEMS device.

[0020] In particular, by controlling parameters such as the size of the anchor points, it is possible to further and effectively avoid significant deformation of the crossbeam due to temperature rise, thereby further ensuring the performance of MEMS devices.

[0021] The MEMS device fabrication method provided in this application uses a planar process of multiple thin film deposition and etching, which is compatible with existing CMOS processes, has low cost, and is easy to promote in practice. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0023] Figure 1 A top view of the upper electrode in the related technology;

[0024] Figure 2 for Figure 1 The diagram shows the upper electrode before and after changes in external temperature;

[0025] Figures 3A-3M A cross-sectional view of a manufacturing process for a MEMS device provided in an embodiment of this application;

[0026] Figure 4 A top view of the first type of second electrode layer provided in the embodiments of this application;

[0027] Figure 5 for Figure 4 A schematic diagram of the second electrode layer before and after changes in external temperature is shown;

[0028] Figure 6 for Figure 4 The second electrode layer is shown in cross-sectional view at XX.

[0029] Figure 7 This is a cross-sectional view of a second type of second electrode layer provided in an embodiment of this application.

[0030] Figure label:

[0031] 100-substrate;

[0032] 200 - Grounding layer;

[0033] 300 - Insulation layer; 310 - Silicon nitride layer; 320 - Silicon oxide layer;

[0034] 400 - First electrode layer; 410 - First groove;

[0035] 500 - Sacrificial layer; 510 - Second groove;

[0036] 600 - Second electrode layer; 610 - Crossbeam; 611 - First end; 612 - Middle part; 613 - Second end; 620 - Anchor point; 621 - First anchoring part; 622 - Second anchoring part; 630 - Fourth groove;

[0037] 700 - Metal layer;

[0038] 810 - Upper electrode; 811 - Anchor point; 812 - Crossbeam; 820 - Lower electrode. Detailed Implementation

[0039] The following uses a MEMS resonant beam device as an example to illustrate the specific implementation of the present invention. Figure 1 This is a top view of the upper electrode layer of a MEMS resonator in related technologies. Figure 2 for Figure 1 The diagram shows the upper electrode before and after changes in external temperature. (Reference) Figure 1 and Figure 2 In related technologies, a MEMS resonator includes an upper electrode 810 and a lower electrode 820 stacked together. The upper electrode 810 may include an anchor point portion 811 and a crossbeam portion 812. The anchor point portion 811 is fixed to one end of the crossbeam portion 812 and connected to the lower electrode 820, leaving the other end of the crossbeam portion 812 suspended above the lower electrode 820. In other words, the end of the crossbeam portion 812 away from the anchor point portion 811 is a free end. Furthermore, the width of the anchor point portion 811 is the same as the width of the crossbeam portion 812.

[0040] refer to Figure 2 At the initial temperature, the crossbeam portion 812a of the upper electrode 810 remains essentially parallel to the lower electrode 820. As the temperature rises, the crossbeam portion 812a deforms and bends towards the lower electrode 820. Figure 2The crossbeam portion 812b is longer than the crossbeam portion 812a by a certain dimension, denoted as ΔD1. This causes a significant change in the gap between the free end of the crossbeam portion 812 and the lower electrode 820, thereby affecting the resonant frequency and leading to temperature drift.

[0041] To address the aforementioned issues, the inventors of this application, through experiments and multiple simulations, believe the cause is likely due to internal stress generated at the anchor point during temperature changes caused by thermal expansion and contraction. The magnitude of this stress is related to the shape and location of the anchor point. In particular, simulation results show that when the anchor point is positioned near the end face of the crossbeam, the amplitude of temperature change at the free end of the crossbeam decreases. It is speculated that this arrangement likely reduces internal stress, thereby minimizing the temperature drift effect of the resonant frequency.

[0042] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0043] Figures 3A-3M A cross-sectional view illustrating the manufacturing process of the MEMS device provided in an embodiment of this application. (See reference...) Figures 3A-3M The manufacturing process for MEMS devices can be as follows:

[0044] refer to Figure 3A S101, Provide a substrate 100. The substrate 100 can be a semiconductor substrate, a semiconductor compound substrate, or an SOI (Semiconductor Over Insulator) substrate. Specifically, the semiconductor substrate can be a silicon substrate. Specifically, the semiconductor compound substrate can be a silicon carbide substrate, a germanium silicide substrate, a gallium arsenide substrate, etc.

[0045] refer to Figure 3B S102. A ground layer 200 is obtained by heavily doping a concentrated boron layer on a substrate 100. The sheet resistance of the ground layer 200 is, for example, less than 3 Ω / □.

[0046] refer to Figure 3C and Figure 3D S103. Deposit an isolation layer 300 on the ground layer 200. The isolation layer 300 can be a single-layer structure, such as a single-layer silicon oxide layer or a single-layer silicon nitride layer, for example... Figure 3C In the structure shown, a silicon nitride layer 310 is used as the isolation layer 300. The isolation layer 300 can also be a multilayer structure, for example... Figure 3DIn the structure shown, the isolation layer 300 includes a silicon nitride layer 310 and a silicon oxide layer 320 stacked together. (The following refers to...) Figure 3D The fabrication process of MEMS devices will be further explained using the structure shown as an example. In addition, the deposition method of the isolation layer 300 can be PECVD (Plasma Enhanced Chemical Vapor Deposition) or LPCVD (Low Pressure Chemical Vapor Deposition).

[0047] refer to Figure 3E S104. A first electrode layer 400 is deposited on the isolation layer 300. Specifically, the first electrode layer 400 can be doped polysilicon. Furthermore, the first electrode layer 400 can be formed by LPCVD.

[0048] refer to Figure 3F S105. Etching the first electrode layer 400. Exemplarily, photoresist can be coated on the first electrode layer 400, and then patterned to form an etching window, exposing the first electrode layer 400 to be etched. The first electrode layer 400 is etched through the etching window to obtain the lower electrode required by the MEMS device, and a lower electrode is formed in the first electrode layer 400. Figure 3F The first groove 410 shown penetrates the first electrode layer 400 and exposes the isolation layer 300 beneath the first electrode layer 400.

[0049] refer to Figure 3G S106. A sacrificial layer 500 is deposited on the first electrode layer 400. The sacrificial layer 500 is also deposited within the first groove 410. Alternatively, PECVD or LPCVD processes can be used to form the sacrificial layer 500. The material of the sacrificial layer 500 can specifically be silicon oxide or phosphosilicate glass (PSG).

[0050] refer to Figure 3H S107. Etching the sacrificial layer 500. Exemplarily, photoresist can be coated on the sacrificial layer 500, and then the photoresist can be patterned to form an etching window, exposing the sacrificial layer 500 to be etched; the sacrificial layer 500 is etched through the etching window to form... Figure 3H The second groove 510 shown penetrates the sacrificial layer 500 and exposes the underlying first electrode layer 400. The cross-sectional shape of the second groove 510 is the same as the cross-sectional shape of the subsequently formed anchor point 620.

[0051] refer to Figure 3IIn step S108, a second electrode layer 600 is formed on the sacrificial layer 500. The second electrode layer 600 also covers the surface of the second groove 510, meaning that the second electrode layer 600 also fills the second groove 510. The material of the second electrode layer 600 can be doped polycrystalline silicon. Furthermore, the second electrode layer 600 can be formed by LPCVD.

[0052] refer to Figure 3J S109. A metal layer 700 is formed on the second electrode layer 600. The metal layer 700 can be made of metal materials such as aluminum. It should be noted that in actual production, the metal layer 700 formed is generally a relatively complete and continuous metal layer, and it also has a certain thickness at the corner of the groove opening of the second groove 510.

[0053] refer to Figure 3K S110, Etching the metal layer 700. That is, patterning the metal layer 700 to meet the requirements of circuit wiring and electrode lead-out.

[0054] refer to Figure 3L S120, Etching the second electrode layer 600. Exemplarily, photoresist can be coated on the surface of the second electrode layer 600 and the patterned metal layer 700, and then the photoresist can be patterned to form an etching window, exposing the second electrode layer 600 to be etched; the second electrode layer 600 is etched through the etching window to form the shape of the upper electrode required for the MEMS device, and to form... Figure 3L The fourth groove 630 shown penetrates the second electrode layer 600 and exposes a portion of the sacrificial layer 500 at its edge.

[0055] refer to Figure 3M S130, Remove the sacrificial layer 500. Specifically, the sacrificial layer 500 is removed by VHF (Vapor Hydrogen Fluoride) etching through the fourth groove 630, thereby creating a gap between the second electrode layer 600 and the first electrode layer 400.

[0056] refer to Figure 3L and Figure 3M The etched second electrode layer 600 has a cantilever beam structure. Specifically, the second electrode layer 600 may include a crossbeam 610 and anchor points 620. The top view of the crossbeam 610 may be rectangular, with its longer side being the length direction of the crossbeam 610 (i.e., the extension direction of the crossbeam 610); the shorter side of the rectangle may be the width direction of the crossbeam 610. (Reference) Figure 3MThe crossbeam 610 may have a first end 611 and a second end 613 along its length, and the middle portion 612 of the crossbeam 610 may be located between the first end 611 and the second end 613. The middle portion 612 of the crossbeam 610 may be suspended above the first electrode layer 400, and the first end 611 of the crossbeam 610 may be fixed to the first electrode layer 400 by means of an anchor point 620.

[0057] Specifically, refer to Figure 3H , Figure 3I as well as Figure 3L In the second groove 510 formed by etching the sacrificial layer 500, in Figure 3I The middle is filled by the second electrode layer 600 to form an anchor point 620. The side of the anchor point 620 opposite to the first electrode layer 400 can form the first end 611 of the crossbeam 610. In this way, the anchor point 620 is sandwiched between the first end 611 of the crossbeam 610 and the first electrode layer 400, and the first end 611 of the crossbeam 610 and the first electrode layer 400 are fixed by the anchor point 620.

[0058] Figure 4 A top view of a first type of second electrode layer provided in an embodiment of this application. (Reference) Figure 4 In this embodiment, the second electrode layer 600 includes a crossbeam 610 and anchor points 620. Anchor points 620 include a first anchoring portion 621 and a second anchoring portion 622, which are spaced apart and fixed to opposite sides of the first end 611 of the crossbeam 610. That is, the first anchoring portion 621 and the second anchoring portion 622 are respectively located on opposite sides of the crossbeam 610 in its width direction, and are a certain distance apart in the width direction of the crossbeam 610. In other words, the side of the first anchoring portion 621 facing the second anchoring portion 622 is aligned with the centerline of the crossbeam 610. Figure 4 The distance between the dashed lines in the middle is ΔD3, where ΔD3 > 0; the distance between the side of the second anchoring part 622 facing the first anchoring part 621 and the center line of the crossbeam 610 is ΔD4, where ΔD4 > 0.

[0059] To illustrate the advantages of the MEMS devices provided in the embodiments of this application, simulation tests were performed on the MEMS devices provided in the embodiments of this application. Figure 5 This is a schematic diagram showing the results of the simulation test. (Reference) Figure 5At the initial temperature (room temperature), the second electrode layer 600 has a crossbeam 610c, which remains essentially horizontal. After the temperature rises to 100°C, the second electrode layer 600 has a crossbeam 610d, which also remains essentially horizontal. The crossbeam 610d is elongated by ΔD2 compared to the crossbeam 610c, without significant bending. Thus, the MEMS device provided in this embodiment can avoid significant bending of the crossbeam 610 of the second electrode layer 600, thereby improving performance.

[0060] It should be noted that the crossbeam 610 can be a cantilever beam structure, that is, the crossbeam 610 has two ends 611, one of which is a fixed end and the other is a free end. The fixed end of the crossbeam 610 is fixed to the first electrode layer 400 through anchor points 620. Alternatively, both ends 611 of the crossbeam 610 can be fixed ends, that is, there are two anchor points 620, and each end 611 is fixed to the first electrode layer 400 through an anchor point 620. The following description uses the crossbeam 610 as a cantilever beam structure as an example to illustrate the setting method of the anchor points 620. For a structure where the crossbeam 610 is fixed at both ends, the setting method of the anchor points 620 in the cantilever beam structure of the crossbeam 610 can be simply derived by referring to it, and will not be repeated here.

[0061] Figure 6 for Figure 4 The cross-sectional view of the second electrode layer at XX shown is for reference. Figure 6 and Figure 4 Optionally, both the first anchoring part 621 and the second anchoring part 622 are sandwiched between the first electrode layer 400 and the end 611 of the crossbeam 610. The fabrication method of the MEMS device corresponding to the anchor point 620 can be found in [reference needed]. Figures 3A-3M .

[0062] In addition, to further prevent the crossbeam 610 from bending, please refer to... Figure 6 Optionally, the first anchoring part 621 may have a first width W1, and the second anchoring part 622 may have a second width W2. The sum of the first width W1 and the second width W2 may be 10% to 50% of the width W of the first end 611 of the crossbeam 610, preferably 10% to 30%; that is, W×10%≤(W1+W2)≤W×50%, preferably, W×10%≤(W1+W2)≤W×30%.

[0063] In addition, to avoid wear and tear on the anchor point 620, optionally, the end face of the first anchoring part 621 away from the second anchoring part 622 may be flush with the end face of the first end 611 of the crossbeam 610; or, the end face of the second anchoring part 622 away from the first anchoring part 621 may be flush with the end face of the first end 611 of the crossbeam 610; or, the end face of the first anchoring part 621 away from the second anchoring part 622 may be flush with the end face of the first end 611 of the crossbeam 610, and the end face of the second anchoring part 622 away from the first anchoring part 621 may be flush with the end face of the first end 611 of the crossbeam 610.

[0064] Furthermore, to improve the uniformity of the second electrode layer 600, the crossbeam 610 may optionally have a plane of symmetry, which may extend along the centerline of the crossbeam 610 (e.g., Figure 4 The dotted line shown is located on the plane of symmetry. In addition, the first anchoring part 621 and the second anchoring part 622 are symmetrical about the plane of symmetry of the crossbeam 610.

[0065] Figure 7 A top view of a second type of second electrode layer provided in an embodiment of this application. (See reference) Figure 7 To reduce the area of ​​the anchor point 620 and thus reduce anchor point 620 wear, optionally, there can be multiple first anchoring portions 621 and second anchoring portions 622. Multiple first anchoring portions 621 can be arranged at intervals along the extension direction of the crossbeam 610, i.e., the length direction of the crossbeam 610, and multiple second anchoring portions 622 can be arranged at intervals along the extension direction of the crossbeam 610. Furthermore, the first anchoring portions 621 and second anchoring portions 622 can be symmetrical about the crossbeam 610.

[0066] It should be noted that for a capacitive MEMS resonator, its main structure is an electrostatic capacitor. One of the electrode plates of this electrostatic capacitor is a movable electrode plate, which includes the first electrode layer and the second electrode layer mentioned above. The other electrode plate of the electrostatic capacitor can adopt a conventional structure, which is not the focus of this application and will not be described in detail. Of course, for a capacitive MEMS resonator, in addition to the substrate and electrodes mentioned above, it also includes other structures such as a ground layer, which can also adopt a conventional structure and will not be described in detail here either.

[0067] Furthermore, this embodiment only uses an electrostatic capacitive MEMS resonator as an example for illustration, but the technical solution of this embodiment is not limited to this. For all MEMS devices with anchor points, such as cantilever beams or double-ended fixed beams, the technical solution provided in this application should achieve good results in avoiding or reducing beam bending caused by factors such as temperature changes or process stress.

[0068] 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.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0070] Although preferred embodiments of this application have been described above, those skilled in the art may make other modifications and variations beyond these embodiments without departing from the spirit of this application and / or beyond the scope of the claims of this application. Such modifications and variations shall fall within the scope of the claims of this application and their equivalents.

Claims

1. A MEMS device, characterized in that, Includes a substrate, and a first electrode layer and a second electrode layer stacked on the substrate, wherein: The second electrode layer includes an anchor point and a crossbeam connected together. The anchor point is supported between at least one end of the crossbeam and the first electrode layer, and the middle part of the crossbeam is suspended above the first electrode layer. The anchor point includes a first anchoring part and a second anchoring part, which are spaced apart and fixed to opposite sides of the end width direction of the crossbeam. The first anchoring part has a first width, and the second anchoring part has a second width. The sum of the first width and the second width is 10% to 50% of the width of the end of the beam.

2. The MEMS device according to claim 1, characterized in that, The crossbeam has a symmetrical plane, and the first anchoring portion and the second anchoring portion are symmetrical about the symmetrical plane of the crossbeam.

3. The MEMS device according to claim 1, characterized in that, The end face of the first anchor portion away from the second anchor portion is flush with the end face of the end of the beam; and / or, the end face of the second anchor portion away from the first anchor portion is flush with the end face of the end of the beam.

4. The MEMS device according to claim 2, characterized in that, The end face of the first anchor portion away from the second anchor portion is flush with the end face of the end of the beam; and / or, the end face of the second anchor portion away from the first anchor portion is flush with the end face of the end of the beam.

5. The MEMS device according to any one of claims 1-4, characterized in that, There are multiple first anchoring parts and multiple second anchoring parts. The multiple first anchoring parts are arranged at intervals along the extension direction of the crossbeam, and the multiple second anchoring parts are arranged at intervals along the extension direction of the crossbeam.

6. The MEMS device according to any one of claims 1-4, characterized in that, The MEMS device includes a MEMS resonator.

7. The MEMS device according to claim 5, characterized in that, The MEMS device includes a MEMS resonator.

8. A method for fabricating a MEMS device, characterized in that, include: A first electrode layer is formed on the substrate, and the first electrode layer is etched to form a first groove penetrating the first electrode layer; A sacrificial layer is formed on the first electrode layer and within the first groove, and the sacrificial layer is etched to form a second groove, the second groove exposing the corresponding first electrode layer; A second electrode layer is formed on the sacrificial layer and the first electrode layer, and the second electrode layer is etched to expose a portion of the sacrificial layer; the etched second electrode layer includes stacked anchor points and crossbeams, the anchor points fill the second groove and are fixed to at least one end of the crossbeams; the anchor points include a first anchoring portion and a second anchoring portion, the first anchoring portion and the second anchoring portion are spaced apart and respectively fixed to opposite sides of the end width direction of the crossbeams; Remove the sacrificial layer to release the crossbeam; The first anchoring part has a first width, and the second anchoring part has a second width. The sum of the first width and the second width is 10% to 50% of the width of the end of the beam.

9. The preparation method according to claim 8, characterized in that, The crossbeam has a symmetrical plane, and the first anchoring portion and the second anchoring portion are symmetrical about the symmetrical plane of the crossbeam.

10. The preparation method according to claim 8, characterized in that, The end face of the first anchor portion away from the second anchor portion is flush with the end face of the end of the beam; and / or, the end face of the second anchor portion away from the first anchor portion is flush with the end face of the end of the beam.

11. The preparation method according to claim 9, characterized in that, The end face of the first anchor portion away from the second anchor portion is flush with the end face of the end of the beam; and / or, the end face of the second anchor portion away from the first anchor portion is flush with the end face of the end of the beam.

12. The preparation method according to any one of claims 8-11, characterized in that, There are multiple first anchoring parts and multiple second anchoring parts. The multiple first anchoring parts are arranged at intervals along the extension direction of the crossbeam, and the multiple second anchoring parts are arranged at intervals along the extension direction of the crossbeam.

13. The preparation method according to any one of claims 8-11, characterized in that, The MEMS device includes a MEMS resonator.

14. The preparation method according to claim 12, characterized in that, The MEMS device includes a MEMS resonator.

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