Microelectromechanical device and method of manufacturing the same

Abstract

The present invention relates to a micro-electro-mechanical device and a method of manufacturing the same. According to one embodiment, a micro-electro-mechanical device comprises: an insulating substrate; a support post disposed on the substrate, the support post supporting a mass; one or more pairs of electrode plates disposed on the substrate around the mass, each pair of electrode plates disposed on opposite sides of the mass; and an insulating cover plate having one or more pairs of electrodes disposed thereon corresponding to the one or more pairs of electrode plates, the one or more pairs of electrodes being in electrical contact with the one or more pairs of electrode plates, respectively, when the cover plate is disposed over the one or more pairs of electrode plates. The micro-electro-mechanical device can be used as an accelerometer or a gyroscope.

Description

Technical Field

[0001] This invention relates to a microelectromechanical device and its manufacturing method. Background Technology

[0002] Microelectromechanical devices (MEMS) are a technology developed comprehensively based on microelectronics, semiconductor manufacturing, and other disciplines. They integrate multiple technical fields such as photolithography, etching, thin film deposition, micromachining, and precision machining, enabling the miniaturization of precision devices to meet the needs of various applications. Common MEMS devices include accelerometers and gyroscopes.

[0003] Current MEMS accelerometers or gyroscopes mostly use two or more cantilever beams to support a mass. The mass can be displaced by acceleration or driven to oscillate. By measuring the capacitance change caused by the mass, acceleration and angular velocity can be measured. However, the manufacturing process of cantilever beams is complex and prone to stress imbalance between the cantilever beams. Summary of the Invention

[0004] To address the aforementioned problems, this invention is proposed. This invention provides a novel MEMS device structure that avoids the use of cantilever beams, exhibits higher durability, and has a simpler structure. This invention also provides a novel MEMS device manufacturing method with simple process steps, which can improve manufacturing yield.

[0005] According to an exemplary embodiment, a microelectromechanical device may include: an insulating substrate; a support pillar disposed on the substrate, the support pillar supporting a mass block; a pair or more pairs of electrode plates disposed on the substrate surrounding the mass block, each pair of electrode plates being disposed on opposite sides of the mass block; and an insulating cover plate having a pair or more pairs of electrodes disposed thereon corresponding to the pair or more pairs of electrode plates, wherein when the cover plate covers the pair or more pairs of electrode plates, the pair or more pairs of electrodes are in electrical contact with the pair or more pairs of electrode plates respectively.

[0006] In some embodiments, the support pillar, the mass block, and the one or more pairs of electrode plates are formed of a conductor or semiconductor material, and conductive leads connected to the support pillar extend from one side of the substrate, and conductive leads connected to the one or more pairs of electrodes extend from one side of the cover plate.

[0007] In some embodiments, the cover plate has an opening located between one or more pairs of electrodes to expose the support post and the mass block.

[0008] In some embodiments, the height of the mass block is lower than the height of the one or more pairs of electrode plates.

[0009] In some embodiments, the microelectromechanical device is used as an accelerometer, and the one or more pairs of electrode plates are used to measure capacitance changes caused by changes in the position of the mass block.

[0010] In some embodiments, the microelectromechanical device is used as a gyroscope, and the one or more pairs of electrode plates include at least a first pair of electrode plates and a second pair of electrode plates. The first pair of electrode plates is used to apply a driving signal to drive the mass block to oscillate between the first pair of electrode plates, and the second pair of electrode plates is used to measure the capacitance change caused by the position change of the mass block.

[0011] According to another exemplary embodiment, a method of manufacturing a microelectromechanical device (MEMS) may include: providing a substrate comprising an insulating substrate and a conductive material layer on the insulating substrate, the conductive material layer comprising a conductor or semiconductor material; forming a first etch mask on the conductive material layer, the etch mask having an annular opening pattern, and etching the conductive material layer to a first depth to form an annular groove and a support pillar surrounded by the annular groove; passivating the sidewalls and bottom of the annular groove to form a passivation layer, removing a portion of the passivation layer at the bottom to expose the conductive material, and continuing to etch the exposed bottom conductive material; repeating the steps of forming the passivation layer, removing a portion of the passivation layer at the bottom, and continuing to etch, wherein the size of the removed bottom passivation layer first gradually decreases, then gradually increases, and then remains constant, until etching down to the insulating substrate, such that the annular groove surrounds... The diameter of the surrounding support column gradually increases, then gradually decreases, and then remains constant to form a structure in which the support column supports the mass block; sacrificial material is formed in the annular groove, the first etching mask is removed, and a second etching mask is formed, the second etching mask covering at least the support column and the mass block, as well as a portion of the conductive material surrounding the sacrificial material; using the second etching mask, the remaining conductive material is etched down to the insulating substrate, and then the second etching mask and the sacrificial material are removed to form one or more pairs of electrode plates surrounding the support column and the mass block, each pair of electrode plates located on opposite sides of the support column and the mass block; one or more pairs of electrodes corresponding to the one or more pairs of electrode plates are formed on the insulating cover plate, and the insulating cover plate is covered on the one or more pairs of electrode plates, such that the one or more pairs of electrodes are in electrical contact with the one or more pairs of electrode plates respectively.

[0012] In some embodiments, the method further includes: forming conductive leads respectively connected to the support post and the one or more pairs of electrodes, wherein the conductive leads connected to the support post extend from one side of the insulating substrate, and the conductive leads connected to the one or more pairs of electrodes extend from one side of the cover plate.

[0013] In some embodiments, the method further includes forming an opening in the cover plate between the one or more pairs of electrodes to expose the support post and the mass block.

[0014] In some embodiments, the microelectromechanical device (MEMS) is used as an accelerometer or a gyroscope. When the MEMS is used as an accelerometer, the one or more pairs of electrode plates are used to measure the capacitance change caused by the positional change of the mass. When the MEMS is used as a gyroscope, the one or more pairs of electrode plates include at least a first pair of electrode plates and a second pair of electrode plates, the first pair of electrode plates being used to apply a drive signal to drive the mass to oscillate between the first pair of electrode plates, and the second pair of electrode plates being used to measure the capacitance change caused by the positional change of the mass.

[0015] The above and other features and advantages of the present invention will become apparent from the following description of exemplary embodiments taken in conjunction with the accompanying drawings. Attached Figure Description

[0016] Figure 1 A schematic diagram of a microelectromechanical device according to an embodiment of the present invention is shown, wherein the cover plate has been removed to show the electrode plate and mass block structure.

[0017] Figure 2 A schematic diagram of the structure of a cover plate of a microelectromechanical device according to an embodiment of the present invention is shown, which can be used for Figure 1 The structure of the microelectromechanical device shown is shown.

[0018] Figure 3A-3L A schematic diagram illustrating a method for manufacturing an electrode plate and a mass block for a microelectromechanical device according to an embodiment of the present invention.

[0019] Figures 4A-4B A schematic diagram illustrating a method for manufacturing a cover plate for a microelectromechanical device according to an embodiment of the present invention. Detailed Implementation

[0020] Figure 1 A schematic diagram of a microelectromechanical device according to an embodiment of the present invention is shown, wherein the cover plate has been removed to show the electrode plate and mass block structure. (Refer to...) Figure 1 The microelectromechanical device (MEMS) includes an insulating substrate 101 on which a plurality of conductive components 102-107 are formed. The insulating substrate 101 may be, for example, a glass substrate, a silicon dioxide substrate, a plastic substrate, or other material layers that can provide support. In some embodiments, the insulating substrate 101 may be an insulating layer in a silicon-on-insulator (SOI) substrate, and the conductive components 102-107 may be made of a thicker silicon layer on top of the insulating layer in the SOI substrate. In some embodiments, the material layers used to form the conductive components 102-107 may also be bonded or attached to the insulating substrate 101.

[0021] A support pillar 102 may be formed on an insulating substrate 101, and a mass block 103 may be supported on the support pillar 102. The support pillar 102 and the mass block 103 may be integrally formed, with the diameter of the mass block 103 being larger than that of the support pillar 102 to form a mass block. The mass block 103 may be located above the support pillar 102, slightly lower than the top of the support pillar 102, or it may be located at the top of the support pillar 102. The mass block 103 may have any shape. Figure 1 The circle shown is only schematic; for example, it can also be rectangular, elliptical, irregular in shape, etc. The support column 102 can have an appropriate aspect ratio (the ratio of height to diameter) so that when acceleration is present, under the inertia of the mass block 103, the support column 102 can undergo bending deformation, thereby causing the position of the mass block 103 to shift.

[0022] One or more pairs of electrode plates may surround the support column 102 and the mass block 103. Figure 1 The diagram schematically illustrates two pairs of electrode plates 104-107, where electrode plates 104 and 105 are disposed on opposite sides of support post 102, and electrode plates 106 and 107 are disposed on opposite sides of support post 102. The straight line connecting the centers of electrode plates 104 and 105 can be substantially perpendicular to the straight line connecting the centers of electrode plates 106 and 107. In some embodiments, only one pair of electrode plates may be provided, or more pairs of electrode plates may be provided. Electrode plates 104-107 may have a tile shape, and their faces towards support post 102 may form an arc shape centered on support post 102, so that the displacement of mass block 103 in all directions is within the radial direction of this arc. Of course, electrode plates 104-107 may also have other shapes, such as a flat plate shape or an arc shape with other curvatures. Electrode plates 104-107 extend vertically upward from substrate 101, and the height of their top ends may be greater than the height of mass block 103. For example, in the vertical direction, the mass block 103 can be located approximately at the center or slightly above the center of the electrode plates 104-107. The support pillar 102, the mass block 103, and the electrode plates 104-107 can be made of conductive materials, including conductors and semiconductors, examples of which include metals, alloys, organic conductive materials, silicon, etc. Furthermore, the support pillar 102 and each of the electrode plates 104-107 are insulated from each other.

[0023] Figure 2 A schematic diagram of the structure of a cover plate of a microelectromechanical device according to an embodiment of the present invention is shown, which can be used for Figure 1 The microelectromechanical device (MEMS) structure is shown. (Refer to...) Figure 2The cover plate 121 is also made of an insulating material, which may be the same as or different from the material of the insulating substrate 101. One or more pairs of electrodes corresponding to one or more pairs of electrode plates on the substrate 101 may be formed on the cover plate 121. Figure 2 Electrodes 124-127 are schematically shown, which correspond to respectively Figure 1 The electrode plates 104-107 are shown. The cover plate 121 may further include an opening 123 formed in the region surrounded by the electrodes 124-127. When the cover plate 121 covers... Figure 1 When used in the MEMS device shown, electrodes 124-127 can contact electrode plates 104-107 respectively, and opening 123 can expose mass block 103. In some embodiments, opening 123 may not be a through hole, but a recessed area, to prevent cover plate 121 from contacting the top of support post 102 and thus hindering the movement of mass block 103.

[0024] Although Figure 1 and Figure 2 Although not shown, conductive leads can also be provided, respectively connected to electrodes 124-127 and support post 102. The leads of electrodes 124-127 can be led out from opening 123, or, if opening 123 is not present, a through electrode can be formed in cover plate 121 to lead out the conductive leads. The leads of support post 102 can be led out from one side of substrate 101, for example, by forming a through electrode in substrate 101 connected to support post 102 to lead out the conductive leads.

[0025] Figure 1 and Figure 2 The MEMS device shown can be used as, for example, an accelerometer or a gyroscope. When used as an accelerometer, one or more pairs of electrode plates 104-107 can each be used to measure the capacitance change caused by the displacement of the mass 103. When acceleration is present, the support column 102 deforms to apply a force to the mass 103 to generate acceleration. The displacement of the mass 103 causes a capacitance change on each electrode plate 104-107. Therefore, by measuring the capacitance between each electrode plate 104-107 and the mass 103, the displacement of the mass 103 can be determined, thereby determining the acceleration.

[0026] When used as a gyroscope, one pair of electrode plates 104-107 can be used as driving electrodes, and the other pair can be used as measuring electrodes. For example, a driving signal can be applied to electrode plates 104 and 105, causing the mass 103 to oscillate back and forth between electrode plates 104 and 105 via electrostatic force. At this time, by measuring the capacitance on electrode plates 106 and 107, the displacement of the mass 103 in the direction of electrode plates 106 and 107 can be determined, which corresponds to the Coriolis force acting on the mass 103, thereby determining the angular velocity of the mass 103.

[0027] Figure 1 and Figure 2 The MEMS device shown can be fabricated using various methods. As an example, a novel fabrication method based on the BOSCH etching process is presented here. Figure 1 The method of the apparatus is shown in Figure 3A-3L The BOSCH etching process, proposed by Robert Bosch, comprises alternating protection and etching steps. The protection step forms a passivation layer on the sidewalls of the etched groove to prevent further etching in subsequent steps. The etching step removes the passivation layer from the bottom of the groove, allowing etching of the exposed material and achieving a high aspect ratio. A characteristic of the BOSCH etching process is the presence of a corrugated structure on the sidewalls of the etched groove. In one embodiment of the invention, the BOSCH process allows for the formation of a single-piece support column and mass block through etching, significantly simplifying the manufacturing process. This single-piece structure is also more robust and durable, extending the device's lifespan.

[0028] First refer to Figure 3A A substrate is provided, comprising an insulating substrate 201 and a conductive material layer 202 disposed on the insulating substrate 201. For example, the substrate may be a silicon-on-insulator substrate, where the insulating substrate 201 is a silicon dioxide layer and the conductive material layer 202 is a bulk silicon layer on the silicon dioxide layer. In other embodiments, the conductive material layer 202, such as a semiconductor layer, may be bonded or attached to the insulating substrate 201, such as a glass substrate, to form a substrate. Figure 3A The substrate shown.

[0029] Reference Figure 3B An etching mask 203, such as a photoresist layer, can be formed on the conductive material layer 202. The etching mask 203 has an annular opening pattern, and the central circular etching mask pattern surrounded by the annular opening pattern can correspond to the support pillar of the MEMS device.

[0030] Reference Figure 3C Using an etching mask 203, the conductive material layer 202 is etched to a first depth to form an annular groove 204 and a support pillar structure 206 surrounded by the annular groove 204 (see...). Figure 3E While this illustration shows the use of the BOSCH etching process to etch to a first depth, thereby forming a wavy feature on the sidewalls of the annular groove 204, since the first depth is not large, conventional etching processes, such as reactive ion etching (RIE) and inductively coupled plasma (ICP) etching, can also be employed. Taking silicon as an example, a mixture of SF6 and O2 gas can be used as the etching gas to generate plasma under a specific radio frequency voltage to perform plasma etching on the silicon layer 202. Furthermore, Figure 3CThe diagram illustrates passivation treatment of the sidewalls and bottom of the groove 204 to form a passivation protective layer 205. For example, C4F8 gas can be used to passivate the silicon material layer 202 to form the protective layer 205. Of course, the etching gas and passivation gas given here are only examples, and other suitable etching gas and passivation gas can be selected according to the material of the conductive material layer 202.

[0031] Continue to refer to Figure 3D A portion of the bottom passivation layer 205 can be removed to expose the conductive material layer 202. In some embodiments, plasma bombardment can be used to remove the bottom passivation layer 205 under a certain bias voltage; the plasma can be generated using SF6 gas. As ion bombardment proceeds, the passivation layer 205 is first removed from the bottom center, and then, as bombardment continues, the passivation layer 205 around the center is gradually removed as well. Therefore, by controlling the duration of ion bombardment, the size of the bottom passivation layer 205 removed can be controlled. For information on the process of forming and removing the passivation protective layer in the BOSCH etching process, please refer to, for example, prior patent application 201280023025.2, or the Baidu Encyclopedia entry on "BOSCH process".

[0032] Reference Figure 3E After removing a portion of the bottom passivation layer 205, etching continues on the conductive material layer 202, and a passivation layer 205 is formed on the newly etched exposed conductive material layer 202. Figure 3F In the next etching step, a portion of the bottom passivation layer 205 is removed again, exposing the underlying conductive material layer 202 for the next etching. During this repeated etch-passivation-passivation layer removal-etching process, the amount of bottom passivation layer 205 removed each time gradually decreases, for example... Figure 3F The size ratio of the bottom passivation layer 205 removed in the middle Figure 3D The size of the bottom passivation layer 205 removed in the middle is smaller. Figure 3G The size ratio of the bottom passivation layer 205 removed in the middle Figure 3F The size of the bottom passivation layer 205 removed in the middle is smaller, so as the etching depth increases, the sidewalls of the annular groove 204 gradually shrink towards the center of the groove, while the diameter of the support pillar 206 gradually increases, forming the mass block 207 (see...). Figure 3I The upper part of ).

[0033] Continue to refer to Figure 3H In the subsequent BOSCH etching process, the size of the removed bottom passivation layer 205 can be gradually increased, causing the sidewalls of the etched groove 204 to expand to both sides, thereby gradually reducing the diameter of the support pillar 206 and forming the mass block 207 (see...). Figure 3IThe lower half of the mass block 207. At this point, the largest diameter portion of the mass block 207 forms the bottleneck portion of the groove 204. However, since the plasma-generating gas can pass through the bottleneck portion and enter the bottom of the groove 204, the generated plasma can remove a larger bottom passivation layer than the bottleneck portion by means of an appropriate bombardment time. By gradually increasing the size of the removed bottom passivation layer, the width of the etched groove 204 can be gradually increased, thereby forming the mass block 207.

[0034] Continue to refer to Figure 3I The size of the removed bottom passivation layer 205 can be maintained, so the width of the etched groove 204 can remain substantially constant, that is, the diameter of the support pillar 206 surrounding the groove 204 remains substantially constant. Etching can continue down to the insulating substrate 201 to obtain the structure of the support pillar 206 and the mass block 207 supported thereon.

[0035] It is understandable that in the BOSCH process steps above, due to the repeated passivation, partial passivation layer removal, and continued etching steps, the sidewalls of the formed groove 204 have many wavy or burr structures. In the following steps, such as Figure 3J As shown, the sidewalls of the groove 204 can be treated with plasma formed by NF3 and CF4 gases at a bias voltage of about 700V to remove burrs or spikes on the sidewalls, thereby making the sidewalls of the groove 204 smoother. Figure 3J This is a schematic diagram showing the smooth sidewalls of the groove. While a perfectly smooth finish may not be achievable in actual manufacturing processes, this step significantly reduces sharp points and burrs on the sidewalls, preventing negative impacts from breakage during subsequent processes or equipment use. Meanwhile, in Figure 3J In the steps shown, the etching mask 203 is removed.

[0036] Continue to refer to Figure 3K A sacrificial material 208 can be formed in the annular groove 204, and a new etching mask 209 can be formed. The etching mask 209 includes a first portion 209a covering the support pillar 206 and the mass block 207, and a second portion 209b covering a portion of the conductive material 202 surrounding the sacrificial material 208. The etching mask 209 may include a plurality of second portions 209b, each corresponding to a plurality of electrode plates to be formed around the support pillar 206.

[0037] Reference Figure 3LThe remaining conductive material 202 is etched using an etching mask 209 until the insulating substrate 201 is exposed. Then, the etching mask 209 and sacrificial material 208 are removed, forming one or more pairs of electrode plates 210 surrounding the support pillar 206 and the mass block 207. Only one pair of electrode plates 210a and 210b are shown in the figure. Each pair of electrode plates can be located on opposite sides of the support pillar 206 and the mass block 207, and can have… Figure 1 The tile shape shown or other shapes.

[0038] Figures 4A-4B A schematic diagram illustrating a method for manufacturing a cover plate for a microelectromechanical device according to an embodiment of the present invention is shown. (Refer to...) Figure 4A An opening 302 can be formed on the insulating cover plate 301. Here, the opening 302 can be a through hole or a recessed area, and the position of the opening 302 can correspond to... Figure 3L The supporting column 206 and the mass block 207 are shown. (Refer to...) Figure 4B A pair of electrodes 303, corresponding to a pair of electrode plates 210 on the insulating substrate 201, are formed around the opening 302 of the insulating cover plate 301. Figure 4B Two pairs of electrodes, 303a, 303b, 303c, and 303d, are shown.

[0039] Although not shown in the figure, conductive leads connected to each electrode 303 can also be formed. When the cover plate 301 has a through-hole opening 302, the conductive leads connected to each electrode 303 can be led out directly from the opening 302; when the cover plate 301 does not have a through-hole opening 302, the conductive leads connected to each electrode 303 can be led out from the side opposite to the electrode 303 using a through electrode passing through the cover plate 301. Similarly, leads connected to the support post 206 can be formed using a through electrode passing through the insulating substrate 201.

[0040] Then, an insulating cover plate 301 can be placed over one or more pairs of electrode plates 210 on the insulating substrate 201, such that one or more pairs of electrodes 303 on the insulating cover plate 301 are in electrical contact with one or more pairs of electrode plates 210 on the insulating substrate 201. As mentioned above, the support post 206, the mass block 207, and each electrode plate 210 can be manipulated using conductive leads, for example, by applying a drive signal or measuring a capacitance signal, to realize the functions of an accelerometer and / or gyroscope.

[0041] Unless the context clearly requires otherwise, throughout the specification and claims, the terms "comprising," "including," etc., shall be interpreted in a encompassing sense, contrary to the meaning of exclusivity or exhaustiveness; that is, they shall be interpreted as "including but not limited to." Furthermore, the terms "in this document," "above," "below," and similar terms, when used in this application, shall refer to the application as a whole, and not to any specific part thereof. Where the context permits, the use of singular or plural terms in the above description may also include either the plural or the singular, respectively. Regarding the term "or" when referring to a list of two or more items, the term encompasses all of the following interpretations: any item in the list, all items in the list, and any combination of items in the list.

[0042] The above detailed description of embodiments of the present invention is not intended to be exhaustive or to limit the invention to the precise forms disclosed above. While specific embodiments and examples of the invention have been described above for illustrative purposes, various equivalent modifications may be possible within the scope of the invention, as those skilled in the art will recognize. For example, although processes or blocks are presented in a given order, alternative embodiments may execute processes having these steps in a different order or employ systems having these blocks in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these processes or blocks may be implemented in various different ways. Furthermore, although processes or blocks are sometimes shown as being executed serially, alternatively, these processes or blocks may also be executed in parallel or at different times.

[0043] The teachings of the invention provided herein can be applied to other systems, not necessarily those described above. Elements and actions of the various embodiments described above can be combined to provide other embodiments.

[0044] While some embodiments of the invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this application. In fact, the novel methods and systems described herein can be implemented in many other forms. Furthermore, various omissions, substitutions, and changes can be made to the form of the methods and systems described herein without departing from the scope of this application.

Claims

1. A microelectromechanical device, comprising: Insulating substrate (101); A support post (102) is disposed on the substrate, the support post supporting a mass block (103), the support post being capable of bending deformation, thereby causing the mass block to shift its position; One or more pairs of electrode plates (104, 105, 106, 107) are disposed on the substrate surrounding the mass block, each pair of electrode plates being disposed on opposite sides of the mass block; and An insulating cover plate (121) is provided with a pair of electrodes corresponding to the pair of electrode plates. When the insulating cover plate covers the pair of electrode plates, the pair of electrodes are in electrical contact with the pair of electrode plates respectively.

2. The microelectromechanical device as claimed in claim 1, wherein, The support column, the mass block, and the one or more pairs of electrode plates are formed of conductor or semiconductor material. The conductive leads connected to the support column are led out from one side of the substrate, and the conductive leads connected to the one or more pairs of electrodes are led out from one side of the insulating cover plate.

3. The microelectromechanical device as described in claim 1, wherein, An opening is formed in the insulating cover plate, the opening being located between one or more pairs of electrodes to expose the support post and the mass block.

4. The microelectromechanical device as claimed in claim 1, wherein, The height of the mass block is lower than the height of the one or more pairs of electrode plates.

5. The microelectromechanical device as claimed in claim 1, wherein, The microelectromechanical device is used as an accelerometer, and the one or more pairs of electrode plates are used to measure the capacitance change caused by the positional change of the mass block.

6. The microelectromechanical device as claimed in claim 1, wherein, The microelectromechanical device is used as a gyroscope, and the one or more pairs of electrode plates include at least a first pair of electrode plates and a second pair of electrode plates. The first pair of electrode plates is used to apply a driving signal to drive the mass block to oscillate between the first pair of electrode plates, and the second pair of electrode plates is used to measure the capacitance change caused by the position change of the mass block.

7. A method for manufacturing a microelectromechanical device, comprising: A substrate is provided, the substrate comprising an insulating substrate and a conductive material layer disposed on the insulating substrate, the conductive material layer comprising a conductor or a semiconductor material; A first etching mask is formed on the conductive material layer, the etching mask having an annular opening pattern, and the conductive material layer is etched to a first depth to form an annular groove and a support post surrounded by the annular groove; The sidewalls and bottom of the annular groove are passivated to form a passivation layer. Part of the passivation layer at the bottom is removed to expose the conductive material, and the exposed bottom conductive material is further etched. Repeat the steps of forming a passivation layer, removing part of the bottom passivation layer, and continuing to etch, wherein the size of the removed bottom passivation layer gradually decreases first, then gradually increases, and then remains constant until the insulating substrate is etched, so that the diameter of the support pillar surrounded by the annular groove gradually increases first, then gradually decreases, and then remains constant, to form a structure in which the support pillar supports the mass block. A sacrificial material is formed in the annular groove, the first etching mask is removed, and a second etching mask is formed, the second etching mask at least covering the support post and the mass block, as well as a portion of the conductive material surrounding the sacrificial material; Using a second etching mask, the remaining conductive material is etched down to the insulating substrate. Then, the second etching mask and the sacrificial material are removed to form one or more pairs of electrode plates surrounding the support pillar and the mass block, with each pair of electrode plates located on opposite sides of the support pillar and the mass block. One or more pairs of electrodes corresponding to the one or more pairs of electrode plates are formed on an insulating cover plate, and the insulating cover plate is covered on the one or more pairs of electrode plates, so that the one or more pairs of electrodes are in electrical contact with the one or more pairs of electrode plates respectively.

8. The method of claim 7, further comprising: Conductive leads are formed to be connected to the support post and the one or more pairs of electrodes respectively, wherein the conductive leads connected to the support post are led out from the side of the insulating substrate, and the conductive leads connected to the one or more pairs of electrodes are led out from the side of the insulating cover plate.

9. The method of claim 7, further comprising: An opening is formed in the insulating cover plate between the one or more pairs of electrodes to expose the support post and the mass block.

10. The method of claim 7, wherein, The microelectromechanical device is used as an accelerometer or gyroscope. When the microelectromechanical device is used as an accelerometer, the one or more pairs of electrode plates are used to measure the capacitance change caused by the positional change of the mass block. When the microelectromechanical device is used as a gyroscope, the one or more pairs of electrode plates include at least a first pair of electrode plates and a second pair of electrode plates. The first pair of electrode plates is used to apply a driving signal to drive the mass block to oscillate between the first pair of electrode plates, and the second pair of electrode plates is used to measure the capacitance change caused by the position change of the mass block.

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