MEMS device and preparation method thereof

Abstract

The invention provides an MEMS device and a preparation method thereof. The MEMS device comprises a piezoelectric vibrating diaphragm, a barrier layer arranged on one side of the piezoelectric vibrating diaphragm, a sacrificial layer connected to the side, away from the piezoelectric vibrating diaphragm, of the barrier layer and a substrate connected to the side, away from the barrier layer, of the sacrificial layer, the substrate comprises a wall connected to the side, away from the barrier layer, of the sacrificial layer, and a cavity is defined by the wall; the substrate further comprises a mass block which is arranged on the side, away from the barrier layer, of the sacrificial layer and contained in the cavity, and the mass block is formed by etching the substrate and is spaced from the wall. The mass block can push the piezoelectric diaphragm to generate remarkable mechanical deformation after capturing and gaining the vibration signal, vibration in the solid medium is effectively captured, and the sensitivity and response efficiency of the MEMS device are improved.

Description

Technical Field

[0001] The present invention belongs to the field of micro-electromechanical technology, and in particular relates to a MEMS device and a preparation method thereof. Background Art

[0002] MEMS (Micro-Electro-Mechanical System) microphones and MEMS accelerometers usually include a diaphragm and a mass block, wherein the diaphragm is used to capture vibrations and convert mechanical vibrations into electrical signals, and the mass block is used to increase the mass of the diaphragm so that the diaphragm produces more significant vibrations.

[0003] However, the diaphragms and mass blocks in current MEMS devices have many limitations. On the one hand, the mass blocks in traditional MEMS devices are limited by the thickness of the deposited materials, making it difficult to meet the requirements of bone conduction microphones and MEMS accelerometers; on the other hand, the diaphragms of traditional MEMS microphones usually have low effective mass and compliance, and can only capture sound waves in the air to generate vibrations, but it is difficult to effectively respond to vibrations in solid media (such as bones). Summary of the invention

[0004] The object of the present invention is to provide a MEMS device and a method for preparing the same, which can improve the sensitivity and response capability of the MEMS device and simplify the method for preparing the MEMS device.

[0005] The technical solution of the present invention is as follows: A first aspect of the present invention provides a MEMS device, comprising a piezoelectric diaphragm, a barrier layer arranged on one side of the piezoelectric diaphragm, a sacrificial layer connected to the barrier layer on a side facing away from the piezoelectric diaphragm, and a substrate connected to the sacrificial layer on a side facing away from the barrier layer, the substrate comprising a wall connected to the sacrificial layer on a side facing away from the barrier layer, the wall enclosing a cavity; the substrate also comprises a mass block arranged on a side of the sacrificial layer facing away from the barrier layer and accommodated in the cavity, the mass block being formed by etching the substrate and spaced apart from the wall.

[0006] Furthermore, the sacrificial layer includes a first supporting portion connecting the wall and the barrier layer and a second supporting portion connecting the mass block and the barrier layer, and there is a gap between the first supporting portion and the second supporting portion.

[0007] Further, the barrier layer includes a barrier layer body disposed between the piezoelectric vibration film and the sacrificial layer, and a first barrier wall and a second barrier wall extending from the barrier layer body toward the substrate side. The first barrier wall is located within the gap and covers the surface of the first support portion facing the second support portion, and the second barrier wall is located within the gap and covers the surface of the second support portion facing the first support portion.

[0008] Further, the sacrificial layer and the barrier layer are made of different materials.

[0009] Further, the piezoelectric vibration film includes a fixing portion supported and fixed to the wall body, and a plurality of cantilever portions extending from the fixing portion above the cavity and suspending the mass block within the cavity. The plurality of cantilever portions are spaced apart from each other or the plurality of cantilever portions are connected to each other as a whole.

[0010] A second aspect of the present invention provides a method for manufacturing a MEMS device, including the steps of: Prepare a substrate; Deposit the sacrificial layer on the surface of the substrate, and deposit the barrier layer on the side of the sacrificial layer facing away from the substrate; Fabricate a piezoelectric vibration film on the side of the barrier layer facing away from the sacrificial layer; Etch the substrate from the side of the substrate facing away from the sacrificial layer to form the wall body and the mass block. The wall body encloses the cavity, and the mass block is received within the cavity and spaced apart from the wall body, and the sacrificial layer is exposed through the gap between the mass block and the wall body.

[0011] Further, after depositing the sacrificial layer on the surface of the substrate, it further includes: Etch the sacrificial layer to form a first channel and a second channel that penetrate the sacrificial layer in the thickness direction. Both the first channel and the second channel are annular and the first channel is disposed around the second channel; The depositing the barrier layer on the side of the sacrificial layer facing away from the substrate includes: Deposit polysilicon on the side surface of the sacrificial layer facing away from the substrate to form a barrier layer body, and deposit polysilicon in the first channel and the second channel respectively to form a first barrier wall and a second barrier wall.

[0012] Further, the etching the substrate from the side of the substrate facing away from the sacrificial layer to form the wall body and the mass block includes: Etch the side of the substrate facing away from the sacrificial layer and form a through hole in the area of the substrate corresponding to the region between the first barrier wall and the second barrier wall, and expose the sacrificial layer through the through hole. The through hole is formed as the gap between the wall body and the mass block.

[0013] Further, after etching the substrate from the side of the substrate facing away from the sacrificial layer to form the wall body and the mass block, it further includes: Etch the sacrificial layer to remove the sacrificial layer located between the first barrier wall and the second barrier wall exposed through the through hole, so as to form a void in the sacrificial layer.

[0014] Further, preparing the piezoelectric vibration film on the surface of the barrier layer facing away from the substrate includes: Deposit a piezoelectric material on the side of the barrier layer facing away from the substrate to form a first piezoelectric layer; Deposit a first electrode material on the side of the first piezoelectric layer facing away from the substrate and pattern it to form a first electrode; Deposit a piezoelectric material on the side of the first electrode facing away from the first piezoelectric layer to form a second piezoelectric layer; Deposit a first electrode material on the side of the second piezoelectric layer facing away from the substrate and pattern it to form a second electrode; Deposit a piezoelectric material on the side of the second electrode facing away from the second piezoelectric layer to form a third piezoelectric layer; Etch the second piezoelectric layer and / or the third piezoelectric layer to form electrode holes, and deposit a conductive material in the electrode holes to lead the first electrode and the second electrode to the surface of the third piezoelectric layer facing away from the substrate.

[0015] The beneficial effects of the present invention are as follows: The mass block of the MEMS device in the present invention is formed by etching the substrate and is accommodated in the cavity formed by etching the substrate. There is no need to additionally deposit and prepare the mass block on the substrate, so that the thickness of the mass block is not limited by the deposition process and can meet the requirements of bone conduction microphones and MEMS accelerometers. After capturing and amplifying the vibration signal, the mass block can push the piezoelectric vibration film to generate a significant mechanical deformation, effectively capturing the vibration in the solid medium and improving the sensitivity and response efficiency of the MEMS device. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the overall structure of a MEMS device provided by an embodiment of the present invention; Figure 2 It is a schematic cross-sectional view of a MEMS device provided by an embodiment of the present invention; Figure 3Schematic diagram of the main process of a method for manufacturing a MEMS device provided by an embodiment of the present invention; Figures 4a to 4k Schematic structural diagram after each step of a method for manufacturing a MEMS device provided by an embodiment of the present invention. Detailed implementation manners

[0017] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] Please refer to Figures 1 to 3 and Figures 4a to 4k An embodiment of the present invention provides a MEMS device, including a piezoelectric vibrating membrane 10, a barrier layer 20 disposed on one side of the piezoelectric vibrating membrane 10, a sacrificial layer 30 connected to the side of the barrier layer 20 facing away from the piezoelectric vibrating membrane 10, and a substrate 40 connected to the side of the sacrificial layer 30 facing away from the barrier layer 20. The substrate 40 includes a wall body 41 connected to the side of the sacrificial layer 30 facing away from the barrier layer 20, and the wall body 41 encloses a cavity 40a; the substrate 40 further includes a mass block 42 disposed on the side of the sacrificial layer 30 facing away from the barrier layer 20 and received in the cavity 40a. The mass block 42 is formed by etching the substrate 40 and is spaced apart from the wall body 41.

[0019] In this embodiment, the mass block 42 of the MEMS device is a part of the substrate 40. The mass block 42 is formed by etching the substrate 40 and received in the cavity 40a formed by the substrate 40. It is necessary to deposit and prepare the mass block 42 additionally on the substrate 40, so that the thickness of the mass block 42 can be independent of the deposition process, and further the size of the mass block 42 can meet the requirements of a bone conduction microphone and a MEMS accelerometer.

[0020] After capturing the vibration signal, the mass block 42 can push the piezoelectric vibrating membrane 10 to generate a significant mechanical deformation. The piezoelectric vibrating membrane 10 converts the vibration signal into a voltage signal based on the piezoelectric effect. The design of the mass block 42 and the piezoelectric vibrating membrane 10 optimizes the sensitivity and response characteristics of the MEMS device, enabling the MEMS device to achieve good acoustic and mechanical performance in the applications of a bone conduction microphone or a MEMS accelerometer.

[0021] The barrier layer 20 in the MEMS device has electrical insulation. The barrier layer 20 is used to isolate the piezoelectric vibrating membrane 10 and the substrate 40, reduce the electrical interference received by the piezoelectric vibrating membrane 10, and maintain the stability and reliability of the MEMS device. In this embodiment, the barrier layer 20 is formed by depositing polysilicon on the surface of the sacrificial layer 30.

[0022] The sacrificial layer 30 in the MEMS device plays a supporting role, used to support the piezoelectric vibrating membrane 10 on one side of the substrate 40. At the same time, the sacrificial layer 30 also has electrical insulation, creating an insulating isolation between the substrate 40 and the piezoelectric vibrating membrane 10.

[0023] Preferably, the wall 41 is annular, and the axis of the wall 41 passes through the symmetry center of the mass block 42, further improving the sensitivity and reliability of the MEMS device.

[0024] Furthermore, as Figure 2 shown, the sacrificial layer 30 includes a first support portion 33 connecting the wall 41 and the barrier layer 20 and a second support portion 34 connecting the mass block 42 and the barrier layer 20, and there is a gap 30a between the first support portion 33 and the second support portion 34.

[0025] In this embodiment, the piezoelectric diaphragm 10 has elasticity, and the gap 30a between the first support portion 33 and the second support portion 34 provides a space for elastic deformation of the piezoelectric diaphragm 10, which helps to effectively transfer the solid vibration to the piezoelectric diaphragm 10 and improve the sensitivity and response efficiency of the MEMS device for capturing vibration signals.

[0026] Furthermore, as Figure 2 shown, the barrier layer 20 includes a barrier layer body 21 disposed between the piezoelectric diaphragm 10 and the sacrificial layer 30, and a first barrier wall 22 and a second barrier wall 23 extending from the barrier layer body 21 toward the substrate 40 side. The first barrier wall 22 is located within the gap 30a and covers the surface of the first support portion 33 facing the second support portion 34, and the second barrier wall 23 is located within the gap 30a and covers the surface of the second support portion 34 facing the first support portion 33.

[0027] The first barrier wall 22 and the second barrier wall 23 have electrical insulation properties. Preferably, both the first barrier wall 22 and the second barrier wall 23 are formed by depositing polysilicon. The first barrier wall 22 and the second barrier wall 23 are not corroded by chemical etchants. During the fabrication process of the MEMS device, the sacrificial layer 30 can be selectively etched to form the gap 30a between the first support portion 33 and the second support portion 34, thereby providing sufficient elastic deformation space for the piezoelectric diaphragm 10.

[0028] Furthermore, the materials of the sacrificial layer 30 and the barrier layer 20 are different. The material of the barrier layer 20 can be polysilicon, and the material of the sacrificial layer 30 can be silicon oxide. The difference in the materials of the sacrificial layer 30 and the barrier layer 20 can prevent the piezoelectric diaphragm from being damaged when the sacrificial layer is etched.

[0029] Preferably, the first barrier wall 22, the second barrier wall 23, and the blocking layer 20 are formed by depositing the same material. The first barrier wall 22, the second barrier wall 23, and the blocking layer 20 are all formed by depositing polysilicon, and the sacrificial layer 30 is formed by depositing silicon oxide. Such an arrangement is conducive to realizing selective etching of the sacrificial layer 30 in the preparation of MEMS devices, thereby increasing the deformation space of the piezoelectric diaphragm 10. There is no need to additionally prepare a mass block 42 on the substrate 40. The mass block 42 formed by etching the substrate 40 can still push the piezoelectric diaphragm 10 to generate significant mechanical deformation after capturing and amplifying the vibration signal.

[0030] Further, the piezoelectric diaphragm 10 includes a fixing portion supported and fixed to the wall body 41 and a plurality of cantilever portions extending upward from the fixing portion above the cavity and suspending the mass block 42 in the cavity 40a. The plurality of cantilever portions are spaced apart from each other or the plurality of cantilever portions are connected to each other as a whole. Along the thickness direction of the piezoelectric diaphragm 10, the portion of the projection of the piezoelectric diaphragm 10 on the substrate 40 that falls within the range of the wall body 41 of the substrate 40 is the fixing portion of the piezoelectric diaphragm 10, and the portion of the projection of the piezoelectric diaphragm 10 on the substrate 40 that falls within the cavity 40a and on the mass block 42 is the cantilever portion. In some embodiments, the plurality of cantilevers are spaced apart. One end of each of the plurality of cantilevers is connected to the first support portion 33, and the other end of the cantilever is connected to the second support portion 34. Each cantilever of the piezoelectric diaphragm 10 can be connected to the mass block 42 through the second support portion 34. When the mass block 42 captures a vibration signal and transmits it to the cantilever, the cantilever bends or deforms, and the cantilever converts the mechanical deformation into an electrical signal based on the piezoelectric effect. In other embodiments, the plurality of cantilevers are connected as a whole and are elastic. The peripheries of the plurality of cantilevers are connected to the fixing portion, and the plurality of cantilevers are connected to the mass block 42 through the second support portion 34.

[0031] Further, as Figure 2 shown, it is defined that the thickness directions of the wall body 41, the mass block 42, and the substrate 40 are the same, and the thickness of the wall body 41 is greater than the thickness of the mass block 42.

[0032] Further, as Figure 2 shown, the piezoelectric diaphragm 10 includes a plurality of piezoelectric layers stacked on the side of the blocking layer 20 away from the substrate 40, a first electrode 14 disposed between any two adjacent piezoelectric layers, a second electrode 15 disposed between any two adjacent piezoelectric layers, a first lead electrode 16 extending from the surfaces of the first electrode 14 and the second electrode 15 to the outermost piezoelectric layer on the side of the blocking layer 20 away from the substrate 40, and a second lead electrode 17 disposed on the surface of the first lead electrode 16.

[0033] In this embodiment, specifically, the multiple piezoelectric layers stacked on the side of the barrier layer 20 away from the substrate 40 are, in sequence, a first piezoelectric layer 11, a second piezoelectric layer 12, and a third piezoelectric layer 13. The first electrode 14 is disposed between the first piezoelectric layer 11 and the second piezoelectric layer 12, and the second electrode 15 is disposed between the second piezoelectric layer 12 and the third piezoelectric layer 13.

[0034] Preferably, the first electrode 14 and the second electrode 15 are Mo, the first lead electrode 16 is Ti, the second lead electrode 17 is Al, and the piezoelectric layer is AlN.

[0035] Further, in this embodiment, please refer to Figures 4a to 4k , a method for manufacturing a MEMS device as described above, includes the steps of: S100. Prepare the substrate 40; S200. Deposit a sacrificial layer 30 on the surface of the substrate 40; S300. Deposit a barrier layer 20 on the side of the sacrificial layer 30 away from the substrate 40; S400. Fabricate a piezoelectric diaphragm 10 on the side of the barrier layer 20 away from the sacrificial layer 30; S500. Etch the substrate 40 from the side of the substrate 40 away from the sacrificial layer 30 to form a wall 41 and a mass 42. The wall 41 encloses a cavity 40a, and the mass 42 is received in the cavity 40a and is spaced apart from the wall 41. The sacrificial layer 30 is exposed through the space between the mass 42 and the wall 41.

[0036] In this embodiment, by etching the substrate 40 to form the wall 41 and the mass 42 nested within the wall 41, there is no need to additionally deposit and form the mass 42 on the substrate 40, so that the size of the mass 42 is not restricted by the deposition process. For the MEMS device fabricated by this manufacturing method, the size of the mass 42 can meet the requirements of a bone conduction microphone and a MEMS accelerometer, with better sensitivity and vibration response characteristics, and can achieve good acoustic and mechanical properties. Moreover, compared with forming the mass 42 by the traditional deposition process, etching the substrate 40 to form the mass 42 reduces the complexity of the manufacturing process of the MEMS device and optimizes the manufacturing method of the MEMS device.

[0037] As Figure 4b shown, further, step S200 includes: S210. Deposit a sacrificial layer 30 on the surface of the first side of the substrate 40; Preferably, in step S210, deposit silicon dioxide on the surface of the first side of the substrate 40 to form the sacrificial layer 30.

[0038] After step S210, the following step is further included: S220. Etch the sacrificial layer 30 to form a first channel 31 and at least one second channel 32 that penetrate the sacrificial layer 30 in the thickness direction. Both the first channel 31 and the second channel 32 are annular, and the first channel 31 is disposed around the second channel 32. As Figure 4c shown, step S300 specifically includes: Deposit polysilicon on the surface of the sacrificial layer 30 facing away from the substrate 40 to form a barrier layer body 21, and deposit polysilicon in the first channel 31 and the second channel 32 respectively to form a first barrier wall 22 and a second barrier wall 23.

[0039] In this embodiment, the barrier layer 20, the first barrier wall 22, and the second barrier wall 23 formed by depositing polysilicon on the sacrificial layer 30 are not corroded by chemical etchants. Their function is to enable the sacrificial layer 30 to be selectively etched.

[0040] Preferably, in this embodiment, in step S220, when etching the sacrificial layer 30, several annular channels that penetrate the sacrificial layer 30 in the thickness direction can also be formed. A part of the several annular channels is disposed around the first channel 31, and another part of the several annular channels is disposed inside the second channel 32.

[0041] Further, step S310 further includes: depositing polysilicon in the several grooves to form corresponding barrier walls.

[0042] It can be understood that in step S300, polysilicon can be deposited on the first channel 31, the second channel 32, and the side of the sacrificial layer 30 facing away from the substrate 40, and the first barrier wall 22, the second barrier wall 23, and the barrier layer 20 can be formed by one deposition, or polysilicon can be first deposited in the first channel 31 and the second channel 32, and then polysilicon can be deposited on the first barrier wall 22, the second barrier wall 23, and the side of the sacrificial layer 30 facing away from the substrate 40 to form the barrier layer 20.

[0043] As Figures 4i to 4j shown, further, step S500 specifically includes: Etch the side of the substrate 40 facing away from the sacrificial layer 30 and form a penetration in the area of the substrate 40 corresponding to between the first barrier wall 22 and the second barrier wall 23, and expose the sacrificial layer 30 through the penetration. The penetration forms a gap between the wall body 41 and the mass block 42.

[0044] In this embodiment, the side of the etching substrate 40 facing away from the sacrificial layer 30 is etched to form a groove 43. Along the thickness direction of the substrate 40, the projection outer peripheral edge of the groove 43 is between the first barrier wall 22 and the second barrier wall 23. Subsequently, the substrate 40 is etched and the sacrificial layer 30 is exposed through penetration. The substrate 40 forms a wall body 41 and a mass block 42 through two etching processes, such that the thickness of the wall body 41 is greater than the thickness of the mass block 42.

[0045] As Figure 4k shown, further, after step 500, it further includes: Step 600: Etch the sacrificial layer 30 to remove the sacrificial layer 30 located between the first barrier wall 22 and the second barrier wall 23 that is exposed through penetration, so as to form a void 30a in the sacrificial layer 30; Among them, the sacrificial layer 30 is etched in a Boe solution to remove the silicon oxide material between the first barrier wall 22, the second barrier wall 23, and the barrier layer 20.

[0046] As Figures 4d to 4h shown, further, step S400 specifically includes: As Figure 4d shown, step S410: Deposit a piezoelectric material on the side of the barrier layer 20 facing away from the substrate 40 to form a first piezoelectric layer 11; Deposit a first electrode 14 material on the side of the first piezoelectric layer 11 facing away from the substrate 40 and pattern it to form a first electrode 14; As Figure 4e shown, step S420: Deposit a piezoelectric material on the side of the first electrode 14 facing away from the first piezoelectric layer 11 to form a second piezoelectric layer 12; Deposit a first electrode material on the side of the second piezoelectric layer 12 facing away from the substrate 40 and pattern it to form a second electrode 15; As Figure 4f shown, step S430: Deposit a piezoelectric material on the side of the second electrode 15 facing away from the second piezoelectric layer 12 to form a third piezoelectric layer 13; As Figure 4g and 4h shown, step S440: Etch the second piezoelectric layer 12 and / or the third piezoelectric layer 13 to form an electrode hole 18, and deposit a conductive material in the electrode hole to lead out the first electrode 14 and the second electrode 15 to the surface of the side of the third piezoelectric layer 13 facing away from the substrate 40.

[0047] Specifically, step S440 includes: As Figure 4gAs shown, in step S441, electrode holes 18 are respectively formed at positions corresponding to the first electrode 14 and the second electrode 15 on the second piezoelectric layer 12 and the third piezoelectric layer 13. A second electrode material is deposited on the side facing away from the third piezoelectric layer 13 so that the second electrode material covers at least the surfaces of the first opening 18 and the second opening 19, thereby forming a first lead-out electrode 16. As Figure 4h shown, in step S442, a third electrode material is deposited on the surface of the region where the first lead-out electrode 16 covers the electrode hole 18, thereby forming a second lead-out electrode 17, such that the first electrode 14 and the second electrode 15 are led out to the surface of the side of the third piezoelectric layer 13 facing away from the substrate 40.

[0048] In this embodiment, the piezoelectric material is AlN, the first electrode material is Mo, the second electrode material is Ti, and the third electrode material is Al. The first piezoelectric layer 11, the second piezoelectric layer 12, the third piezoelectric layer 13, the first electrode 14, and the second electrode 15 form a stacked piezoelectric vibration film 10, and the piezoelectric vibration film 10 can convert a vibration signal into an electrical signal based on the piezoelectric effect.

[0049] It should be noted that, for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0050] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0051] The above are only the implementation manners of the present invention. It should be pointed out here that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, improvements can still be made, but these all fall within the protection scope of the present invention.

Claims

1. A MEMS device, comprising a piezoelectric diaphragm, a barrier layer disposed on one side of the piezoelectric diaphragm, a sacrificial layer connected to the barrier layer on a side away from the piezoelectric diaphragm, and a substrate connected to the sacrificial layer on a side away from the barrier layer, wherein the substrate comprises a wall connected to the sacrificial layer on a side away from the barrier layer, and the wall encloses a cavity; characterized in that: The substrate further includes a mass block disposed on a side of the sacrificial layer away from the barrier layer and contained in the cavity. The mass block is formed by etching the substrate and is spaced apart from the wall.

2. The MEMS device according to claim 1, characterized in that: The sacrificial layer includes a first supporting portion connecting the wall and the barrier layer and a second supporting portion connecting the mass block and the barrier layer, and a gap exists between the first supporting portion and the second supporting portion.

3. The MEMS device according to claim 2, characterized in that: The barrier layer includes a barrier layer body arranged between the piezoelectric diaphragm and the sacrificial layer, and a first barrier wall and a second barrier wall extending from the barrier layer body toward one side of the substrate, the first barrier wall is located in the gap and covers the surface of the first support part facing the second support part, and the second barrier wall is located in the gap and covers the surface of the second support part facing the first support part.

4. The MEMS device according to claim 1, characterized in that: The sacrificial layer and the barrier layer are made of different materials.

5. The MEMS device according to claim 1, characterized in that: The piezoelectric diaphragm includes a fixed portion supported and fixed to the wall and a plurality of cantilever portions extending from the fixed portion toward the top of the cavity and suspending the mass block in the cavity. The plurality of cantilever portions are spaced apart from each other or connected to each other as a whole.

6. A method for preparing a MEMS device as claimed in claim 1, characterized in that: Includes steps: preparing a substrate; Depositing the sacrificial layer on the surface of the substrate, and depositing the barrier layer on a side of the sacrificial layer facing away from the substrate; Prepare a piezoelectric diaphragm on a side of the barrier layer away from the sacrificial layer; The substrate is etched from a side of the substrate away from the sacrificial layer to form the wall and the mass block, wherein the wall encloses the cavity, and the mass block is accommodated in the cavity and spaced apart from the wall, and the sacrificial layer is exposed through the space between the mass block and the wall.

7. The method for preparing a MEMS device according to claim 6, characterized in that: After depositing the sacrificial layer on the surface of the substrate, the method further includes: Etching the sacrificial layer to form a first channel and a second channel penetrating the sacrificial layer in a thickness direction, wherein the first channel and the second channel are both annular and the first channel is disposed around the second channel; The step of depositing the barrier layer on a side of the sacrificial layer facing away from the substrate comprises: Polysilicon is deposited on a surface of the sacrificial layer facing away from the substrate to form a barrier layer body, and polysilicon is deposited in the first channel and the second channel to form a first barrier wall and a second barrier wall respectively.

8. The method for preparing a MEMS device according to claim 7, characterized in that: The step of etching the substrate from a side of the substrate away from the sacrificial layer to form the wall and the mass block comprises: The side of the substrate facing away from the sacrificial layer is etched to form a through hole in the region of the substrate corresponding to between the first barrier wall and the second barrier wall and expose the sacrificial layer through the through hole, wherein the through hole forms a gap between the wall and the mass block.

9. The method for preparing a MEMS device according to claim 8, characterized in that: After etching the substrate from a side of the substrate away from the sacrificial layer to form the wall and the mass block, the method further includes: The sacrificial layer is etched to remove the sacrificial layer between the first barrier wall and the second barrier wall exposed by the through-hole, so as to form a gap in the sacrificial layer.

10. The method for preparing a MEMS device according to claim 6, characterized in that: The step of preparing a piezoelectric diaphragm on a surface of the barrier layer facing away from the substrate comprises: Depositing a piezoelectric material on a side of the barrier layer facing away from the substrate to form a first piezoelectric layer; Depositing a first electrode material on a side of the first piezoelectric layer facing away from the substrate and patterning the first electrode; Depositing a piezoelectric material on a side of the first electrode away from the first piezoelectric layer to form a second piezoelectric layer; Depositing a first electrode material on a side of the second piezoelectric layer facing away from the substrate and patterning the first electrode to form a second electrode; Depositing a piezoelectric material on a side of the second electrode away from the second piezoelectric layer to form a third piezoelectric layer; The second piezoelectric layer and / or the third piezoelectric layer are etched to form electrode holes, and a conductive material is deposited in the electrode holes to lead the first electrode and the second electrode to a surface of the third piezoelectric layer that is away from the substrate.

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