A MEMS accelerometer device structure and a preparation method thereof

Abstract

The present invention provides a MEMS accelerometer device structure and a preparation method thereof, belonging to the technical field of MEMS accelerometers. The MEMS accelerometer device structure includes a signal interconnection wafer, a device layer and a cover plate; at least one first cavity is formed between the device layer and the cover plate, and at least one second cavity is formed between the signal interconnection wafer and the device layer; at least one first through hole is provided on the cover plate, and / or at least one second through hole is provided on the signal interconnection wafer; the device structure further includes a first hole-sealing layer for sealing the first through hole and / or a second hole-sealing layer for sealing the second through hole. In the preparation method of the device structure, the step of plating a hydrophobic material is moved to after the component bonding step, which not only does not affect the device sealing performance, but also avoids the influence of the hydrophobic material on temperature, and ensures that all the surfaces inside the device structure can be plated with the hydrophobic material, achieving a better anti-bonding effect.

Description

Technical Field

[0001] The present invention relates to the field of microelectronics technology, and more particularly to the field of MEMS accelerometer technology, and specifically relates to a MEMS accelerometer device structure capable of preventing adhesion and a preparation method thereof. Background Art

[0002] Existing MEMS (Micro Electromechanical System) accelerometers require a suspended sensing structure (movable device layer) so that the sensing structure can bend or move in a designed direction to detect the acceleration value. However, when the accelerometer encounters a situation of excessive acceleration, the sensing structure may undergo excessive displacement and adhere to the upper and lower structures, resulting in the failure of the accelerometer. This phenomenon is one of the common reliability failure problems of MEMS accelerometers. To address this problem, the current main solution is to coat a hydrophobic material (usually perfluorodecyltrimethoxysilane, FDTS) on the side of the device layer before bonding it to a silicon wafer layer interconnected with signals, so that it is not easy for structures to adhere to each other.

[0003] In the prior art, usually after the device side is formed, a hydrophobic material surface layer is formed by air coating, and then the hydrophobic material in the bonding area is removed and bonded to the wire interconnect substrate. This solution has the following problems: (1) Before bonding, it is necessary to remove the hydrophobic material on the surface of the bonding material, but at the same time, the hydrophobic material on the surface of other materials should be retained. Usually, this step is achieved by high-temperature treatment (the removal temperature of the hydrophobic material on different material surfaces is different). However, because the hydrophobic material on the surface of other materials should be protected from being damaged as much as possible, the temperature of this step should not be too high. Therefore, it is very difficult to completely remove the hydrophobic material on the surface of the bonding material, and usually there will be some residues. And the residual hydrophobic material will affect the quality of the bonding seal. (2) Since the bonding temperature is relatively high, usually reaching above 420 °C, and the hydrophobicity of the hydrophobic material deteriorates rapidly with the increase of temperature above 400 °C (as Figure 1 shown), the hydrophobic material on the surface of the sensing structure will also be damaged to a certain extent during the bonding process, thus reducing the effect of preventing adhesion. (3) Since the sensing material and the bonding material are usually the same material on the side of signal interconnection, it is impossible to selectively remove the hydrophobic material in the bonding area, so the hydrophobic material cannot be coated on this side structure, and therefore the best anti-adhesion effect cannot be achieved. Summary of the Invention

[0004] To solve at least one of the above problems, the present invention provides a MEMS accelerometer device structure. By providing through holes in the MEMS accelerometer device structure, it can be ensured that a hydrophobic material is coated on all surfaces inside the device via the through holes.

[0005] Specifically, the present invention adopts the following technical solutions:

[0006] A MEMS accelerometer device structure includes a signal interconnection wafer, a device layer, and a cover plate from bottom to top; at least one first cavity is formed between the device layer and the cover plate, and at least one second cavity is formed between the signal interconnection wafer and the device layer; at least one first through-hole is provided on the cover plate, and / or at least one second through-hole is provided on the signal interconnection wafer; at least one first sealing layer is provided on the surface of the cover plate away from the device layer to seal the first through-hole; and / or at least one second sealing layer is provided on the surface of the signal interconnection wafer away from the device layer to seal the second through-hole.

[0007] In some embodiments, the MEMS accelerometer device structure further includes a hydrophobic layer formed through the first through-hole and / or the second through-hole, and the hydrophobic layer is located on the inner wall of each first cavity, the inner wall of each second cavity, and the inner wall of each first through-hole and / or each second through-hole.

[0008] In some embodiments, the depth of the first through-hole is 20 - 300 μm.

[0009] In some embodiments, the inner diameter of the cross-section of the first through-hole is 1 - 10 μm.

[0010] In some embodiments, the depth of the first through-hole is 20 - 300 μm, and the inner diameter of the cross-section of the first through-hole is 1 - 10 μm.

[0011] In some embodiments, the depth of the second through-hole is 20 - 300 μm.

[0012] In some embodiments, the inner diameter of the cross-section of the second through-hole is 1 - 10 μm.

[0013] In some embodiments, the depth of the second through-hole is 20 - 300 μm, and the inner diameter of the cross-section of the second through-hole is 1 - 10 μm.

[0014] In some embodiments, the depth of the first through-hole is 20 - 300 μm, and the depth of the second through-hole is 20 - 300 μm.

[0015] In some embodiments, the inner diameter of the cross-section of the first through-hole is 1 - 10 μm, and the inner diameter of the cross-section of the second through-hole is 1 - 10 μm.

[0016] In some embodiments, the material of the first sealing layer is any one of silicon dioxide, silicon, or silicon nitride.

[0017] In some embodiments, the material of the second hole-sealing layer is any one of silicon dioxide, silicon, or silicon nitride.

[0018] In some embodiments, the signal-interconnect wafer includes a plurality of metal layers, and interconnect vias are provided between the plurality of metal layers.

[0019] In some embodiments, the metal of the metal layer is aluminum or copper.

[0020] The present invention also provides a method for manufacturing the MEMS accelerometer device structure, including the following steps:

[0021] S1. Combine the cover plate with the device layer, and combine the surface of the device layer away from the cover plate with the signal-interconnect wafer; or combine the device layer with the signal-interconnect wafer, and combine the surface of the device layer away from the signal-interconnect wafer with the cover plate.

[0022] S2. Thinning the cover plate, and etching at least one first via hole on the thinned cover plate; or / and thinning the signal-interconnect wafer, and etching at least one second via hole on the thinned signal-interconnect wafer.

[0023] S3. Performing a hydrophobic material coating treatment on the overall device structure by gaseous coating.

[0024] S4. Performing a hole-sealing treatment on the first via hole or / and the second via hole on the device structure obtained in step S3 to obtain an anti-adhesion MEMS accelerometer.

[0025] In some embodiments, in step S2, the thickness of the cover plate is thinned to 20 - 300 μm.

[0026] In some embodiments, in step S2, the thickness of the signal-interconnect wafer is thinned to 20 - 300 μm.

[0027] In some embodiments, in step S2, the inner diameter of the cross-section of the first via hole is etched to be 1 - 10 μm.

[0028] In some embodiments, in step S2, the inner diameter of the cross-section of the second via hole is etched to be 1 - 10 μm.

[0029] In some embodiments, the method for performing a hole-sealing treatment on the first via hole in step S4 includes: plating a hole-sealing material on the surface of the cover plate facing away from the device layer or / and bonding at least one wafer to obtain a first hole-sealing layer. The wafer is preferably a silicon wafer or a glass wafer.

[0030] In some embodiments, before plating the hole-sealing material, the hydrophobic material on the surface of the cover plate facing away from the device layer is removed by physical bombardment.

[0031] In some embodiments, the method for sealing the second through-hole in step S4 includes: plating a sealing material and / or bonding at least one wafer on the surface of the signal interconnection wafer facing away from the device layer to obtain a second sealing layer. The wafer is preferably a silicon wafer or a glass wafer.

[0032] In some embodiments, before plating the sealing material, a hydrophobic material on the surface of the signal interconnection wafer away from the device layer is removed by physical bombardment.

[0033] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the cover plate is first combined with the device layer or the device layer is first combined with the signal interconnection wafer, at least one first cavity is formed between the cover plate and the device layer, and at least one second cavity is formed between the device layer and the signal interconnection wafer; then at least one first through-hole is etched on the cover plate, and / or at least one second through-hole is etched on the signal interconnection wafer; since the device layer has many grooves, therefore, the hydrophobic material can be plated onto all the inner surfaces of the device structure through the first through-hole, the second through-hole and the grooves penetrating the device layer, so that the step of plating the hydrophobic material is postponed to be carried out after the component combination step, which not only avoids the problem of poor sealing due to the residual hydrophobic material during component combination, but also ensures that the hydrophobic material is not affected by the temperature during combination, and can also achieve that all the inner surfaces of the device structure can be plated with the hydrophobic material, and finally achieves a better anti-adhesion effect. Description of the Drawings

[0034] Figure 1 It is a graph showing the hydrophobicity of various hydrophobic materials varying with temperature;

[0035] Figure 2 It is a schematic diagram of the bonded device structure in step S1 of Example 2;

[0036] Figure 3 It is a schematic diagram of the device structure after thinning the cover plate in step S2 of Example 2;

[0037] Figure 4 It is a schematic diagram of the device structure after forming the first through-hole on the cover plate in step S2 of Example 2;

[0038] Figure 5 It is a schematic diagram of the device structure after performing the hydrophobic material plating treatment on the device structure obtained in step S2 in step S3 of Example 2;

[0039] Figure 6 It is a schematic diagram of the MEMS accelerometer device structure capable of preventing adhesion obtained in Example 2, and is also one of the structures of the MEMS accelerometer device structure capable of preventing adhesion provided in Example 1;

[0040] Figure 7 Schematic diagram of the MEMS accelerometer device structure obtained in Example 4 that can prevent adhesion;

[0041] Figure 8 Schematic diagram of the MEMS accelerometer device structure obtained in Example 6 that can prevent adhesion;

[0042] Figure 9 Schematic diagram of the MEMS accelerometer device structure obtained in Example 7 that can prevent adhesion;

[0043] Figure 10 Schematic diagram of the MEMS accelerometer device structure prepared in Example 8 that can prevent adhesion.

[0044] In the figure: 1, cover plate; 2, device layer; 3, signal interconnection wafer; 41, first cavity; 42, second cavity; 51, first through hole; 52, second through hole; 53, trench; 6, hydrophobic layer; 71, first hole-sealing layer; 72, second hole-sealing layer; 8, wafer. Detailed implementation manners

[0045] The following content describes the technical solutions of the present invention clearly and completely in combination with embodiments, so that those skilled in the art can fully understand the present invention. Obviously, the described embodiments are only some preferred embodiments of the present invention, rather than all embodiments. Any equivalent transformation or substitution made by those of ordinary skill in the art without creative efforts to the following implementation manners shall fall within the protection scope of the present invention.

[0046] The methods not described in detail in the following embodiments are conventional methods well known to those skilled in the art. The terms "first", "second", etc. in the present invention are only used for descriptive purposes to distinguish similar objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0047] Example 1

[0048] As Figure 6As shown in the figure, this embodiment provides a MEMS accelerometer device structure capable of preventing adhesion, which includes a signal interconnection wafer 3, a device layer 2, and a cover plate 1 from bottom to top. A plurality of first cavities 41 are formed between the device layer 2 and the cover plate 1. A plurality of second cavities 42 are formed between the signal interconnection wafer 3 and the device layer 2. A first through hole 51 is provided on the cover plate 1. Since the device layer 2 has a plurality of grooves 53, hydrophobic material can form a hydrophobic layer 6 on the inner walls of each first cavity 41, the inner walls of each second cavity 42, the inner walls of each first through hole 51, and the inner walls of each groove 53 (i.e., all inner surfaces of the MEMS accelerometer device structure) via the first through hole 51 and the grooves 53. A first hole-sealing layer 71 is provided on the surface of the cover plate 1 away from the device layer 2 to seal the first through hole 51.

[0049] Further, as Figure 7 shown, the number of the first through holes 51 located on the cover plate 1 can be multiple, such as 2; for another example, 3, 4, 5...

[0050] Further, as Figure 7 shown, a second through hole 52 can be provided on the signal interconnection wafer 3, and the number of the second through holes 52 can be one or more. The function of the second through hole 52 is the same as that of the first through hole 51, mainly used to form a hydrophobic layer 6 on all inner surfaces of the MEMS accelerometer device structure. When at least one second through hole 52 is provided on the signal interconnection wafer 3, the first through hole 51 does not have to be provided on the cover plate 1, or one or more first through holes 51 can also be provided on the cover plate 1.

[0051] It should be noted that when plating the hydrophobic material on the device, the hydrophobic layer will be plated on both the inner surface and the exposed surface of the device. The hydrophobic layer 6 in this embodiment refers to the hydrophobic layer formed by the hydrophobic material entering the device interior through the first through hole 51 or / and the second through hole 52, and does not include the hydrophobic layer on the exposed surface of the device structure. In this application, the device layer 2 has a movable structure and a plurality of grooves 53, and at least one of the grooves penetrates the device layer 2.

[0052] Embodiment 2

[0053] This embodiment provides a preparation method of a MEMS accelerometer device structure capable of preventing adhesion, including the following steps:

[0054] S1. As Figure 2 shown, bond the device layer 2 and the cover plate 1, and bond the surface of the device layer 2 away from the cover plate 1 with the signal interconnection wafer 3. A plurality of first cavities 41 are formed between the cover plate 1 and the device layer 2, and a plurality of second cavities 42 are formed between the signal interconnection wafer 3 and the device layer 2. The device layer 2 has a movable structure and a plurality of grooves 53.

[0055] S2. As Figure 3 shown, the cover plate 1 is thinned to a thickness of 150 μm. As Figure 4 shown, a first through hole 51 is formed on the thinned cover plate 1 by a photolithography process.

[0056] S3. As Figure 5 shown, the overall device structure is coated with a hydrophobic material by vapor deposition, so that the gaseous molecules of the hydrophobic material enter the interior of the device structure through the first through hole 51, and hydrophobic layers 6 are coated on the inner walls of the first through hole 51, the inner wall of the first cavity 41, the inner wall of the second cavity 42, and the inner wall of the groove 53, thereby realizing the coating treatment of all structural surfaces (including the inner and outer surfaces of the device).

[0057] S4. As Figure 6 shown, after the coating of the hydrophobic material is completed, a sealing material (such as silicon dioxide) is coated on the upper surface of the cover plate 1 of the device structure to seal the first through hole 51. To ensure better adhesion between the first sealing layer 71 obtained after coating the sealing material and the cover plate 1, the hydrophobic material on the upper surface of the cover plate 1 can be removed by physical bombardment (such as conventional argon ion bombardment) before coating the sealing material.

[0058] It should be noted that the number and opening positions of the first through holes 51 in step S2 can be adjusted according to actual requirements.

[0059] Embodiment 3

[0060] The method for preventing the adhesion of the MEMS accelerometer device structure in this embodiment is basically the same as that in Embodiment 1, except that:

[0061] In step S1, the device layer 2 is bonded to the signal interconnection wafer 3, and the surface of the device layer 2 away from the signal interconnection wafer 3 is bonded to the cover plate 1.

[0062] In step S2, the cover plate 1 is thinned to a thickness of 20 μm; a plurality of (such as 4) first through holes 51 are formed on the thinned cover plate 1 by an etching process.

[0063] Embodiment 4

[0064] This embodiment provides a method for preparing a MEMS accelerometer device structure capable of preventing adhesion, including the following steps:

[0065] S1. As Figure 2 shown, the device layer 2 is bonded to the cover plate 1, and the surface of the device layer 2 away from the cover plate 1 is bonded to the signal interconnection wafer 3. A plurality of first cavities 41 are formed between the cover plate 1 and the device layer 2, and a plurality of second cavities 42 are formed between the signal interconnection wafer 3 and the device layer 2.

[0066] S2. As shown in Figure 3 , the cover plate 1 is thinned to a thickness of 300 μm. Multiple (e.g., 2) first through-holes 51 are formed on the thinned cover plate 1 by an etching process (as shown in Figure 7 ). The signal interconnection wafer 3 is thinned to a thickness of 20 μm, and a second through-hole 52 is formed on the signal interconnection wafer 3 (as shown in Figure 7 ).

[0067] S3. The overall device structure is coated with a hydrophobic material by vapor deposition, so that the gaseous molecules of the hydrophobic material enter the interior of the device structure through the first through-hole 51 and the second through-hole 52, and hydrophobic layers 6 are coated on the inner walls of the first through-hole 51, the second through-hole 52, the inner wall of the first cavity 41, the inner wall of the second cavity 42, and the inner wall of the groove 53, thereby realizing the coating treatment of all structural surfaces (including the inner and outer surfaces of the device).

[0068] S4. As shown in Figure 7 , after the coating of the hydrophobic material is completed, a hole-sealing material (e.g., silicon nitride) is coated on the upper surface of the cover plate 1 of the device structure to seal the first through-hole 51. To ensure better adhesion between the first hole-sealing layer 71 obtained after coating the hole-sealing material and the cover plate 1, the hydrophobic material on the upper surface of the cover plate 1 can be removed by physical bombardment (e.g., conventional argon ion bombardment) before coating the hole-sealing material. A hole-sealing material (e.g., silicon dioxide) is coated on the lower surface of the signal interconnection wafer 3 to seal the second through-hole 52. To ensure better adhesion between the second hole-sealing layer 72 obtained after coating the hole-sealing material and the signal interconnection wafer 3, the hydrophobic material on the lower surface of the signal interconnection wafer 3 can be removed by physical bombardment (e.g., conventional argon ion bombardment) before coating the hole-sealing material.

[0069] It should be noted that the number and opening positions of the first through-holes 51 and the number and opening positions of the second through-holes 52 can be adjusted according to actual requirements.

[0070] Embodiment 5

[0071] This embodiment provides a method for preparing a MEMS accelerometer device structure capable of preventing adhesion, including the following steps:

[0072] S1. As shown in Figure 2 , the device layer 2 is bonded to the cover plate 1, and the surface of the device layer 2 away from the cover plate 1 is bonded to the signal interconnection wafer 3. Multiple first cavities 41 are formed between the cover plate 1 and the device layer 2, and multiple second cavities 42 are formed between the signal interconnection wafer 3 and the device layer 2.

[0073] ​​​​​​​​​​S2. Thin the signal-interconnect wafer 3 to a thickness of 300 μm, and form a plurality of (e.g., 3) second vias 52 on the signal-interconnect wafer 3 through an etching process.

[0074] S3. Treat the overall device structure by vapor deposition of a hydrophobic material, so that the gaseous molecules of the hydrophobic material enter the interior of the device structure through the second vias 52, and hydrophobic layers 6 are deposited on the inner walls of the second vias 52, the inner walls of the first cavity 41, the inner walls of the second cavity 42, and the inner walls of the trenches 53, thereby realizing the coating treatment on all structural surfaces (including the inner and outer surfaces of the device).

[0075] S4. After the deposition of the hydrophobic material is completed, deposit a sealing material (e.g., silicon nitride) on the surface of the signal-interconnect wafer 3 of the device structure away from the device layer 2 to seal the second vias 52. To ensure better adhesion between the resulting second sealing layer 72 and the signal-interconnect wafer 3 after the deposition of the sealing material, the hydrophobic material on the surface of the signal-interconnect wafer 3 away from the device layer 2 can be removed by physical bombardment (e.g., conventional argon ion bombardment) before the deposition of the sealing material.

[0076] It should be noted that the number and opening positions of the second vias 52 can be adjusted according to actual requirements.

[0077] Embodiment 6

[0078] In this embodiment, the preparation method of the MEMS accelerometer device structure capable of preventing adhesion is basically the same as that of Embodiment 2, except that:

[0079] As Figure 8 shown, step S4 further includes the step of bonding a wafer 8 on the upper surface of the first sealing layer 71. Bonding the wafer 8 on the upper surface of the first sealing layer 71 can make the sealing performance of the first via 51 better and also improve the firmness of the structure near the first via 51.

[0080] In other embodiments, the second vias 52 can also be sealed by directly bonding a wafer on the surface of the signal-interconnect wafer 3 away from the device layer 2.

[0081] Embodiment 7

[0082] In this embodiment, the preparation method of the MEMS accelerometer device structure capable of preventing adhesion is basically the same as that of Embodiment 2, except that:

[0083] As Figure 9 shown, in step S4, a wafer 8 is directly bonded on the upper surface of the cover plate 1 of the device structure after the deposition of the hydrophobic material to seal the first via 51.

[0084] In other embodiments, the second through-hole 52 can also be sealed by directly bonding a wafer to the surface of the signal interconnect wafer 3 away from the device layer 2.

[0085] Example 8

[0086] As Figure 10 shown, the method for preparing a MEMS accelerometer device structure capable of preventing adhesion in this embodiment includes the following steps:

[0087] S1. Bond the device layer 2 to the cover plate 1, and bond the surface of the device layer 2 away from the cover plate 1 to the signal interconnect wafer 3. A plurality of first cavities 41 are formed between the cover plate 1 and the device layer 2, and a plurality of second cavities 42 are formed between the signal interconnect wafer 3 and the device layer 2. The device layer 2 has a movable structure and a plurality of grooves 53.

[0088] S2. Thinning the signal interconnect wafer 3 to a thickness of 200 μm. A second through-hole 52 is formed on the thinned signal interconnect wafer 3 by photolithography.

[0089] S3. Coating the entire device structure with a hydrophobic material by gaseous coating, so that the gaseous molecules of the hydrophobic material enter the interior of the device structure through the second through-hole 52, and hydrophobic layers 6 are coated on the inner walls of the second through-hole 52, the inner walls of the first cavities 41, the inner walls of the second cavities 42, and the inner walls of the grooves 53, thereby realizing coating treatment on all structural surfaces (including the inner and outer surfaces of the device).

[0090] S4. After coating with the hydrophobic material, a sealing material (such as silicon dioxide) is coated on the bottom surface of the signal interconnect wafer 3 of the device structure to seal the second through-hole 52. To ensure better adhesion between the second sealing layer 72 obtained after coating the sealing material and the signal interconnect wafer 3, the hydrophobic material on the bottom surface of the signal interconnect wafer 3 can be removed by physical bombardment (such as conventional argon ion bombardment) before coating the sealing material.

[0091] The above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. For any person skilled in the art, the present invention can have various changes and modifications. Any simple equivalent changes and modifications made according to the protection scope of the present invention application and the content of the specification shall be included in the protection scope of the present invention.

Claims

1. A MEMS accelerometer device structure, characterized in that, It includes, from bottom to top, a signal-interconnecting wafer, a device layer, and a cover plate; at least one first cavity is formed between the device layer and the cover plate, and at least one second cavity is formed between the signal-interconnecting wafer and the device layer; at least one first through-hole is provided on the cover plate, and / or at least one second through-hole is provided on the signal-interconnecting wafer; at least one first hole-sealing layer is provided on the surface of the cover plate away from the device layer for sealing the first through-hole; and / or at least one second hole-sealing layer is provided on the surface of the signal-interconnecting wafer away from the device layer for sealing the second through-hole; the MEMS accelerometer device structure further includes a hydrophobic layer formed through the first through-hole and / or the second through-hole, and the hydrophobic layer is located on the inner walls of each first cavity, each second cavity, and the inner wall of each first through-hole and / or each second through-hole.

2. The MEMS accelerometer device structure according to claim 1, wherein The depth of the first through-hole is 20 - 300 μm; and / or the inner diameter of the cross-section of the first through-hole is 1 - 10 μm.

3. The MEMS accelerometer device structure according to claim 1, characterized in that, The depth of the second through-hole is 20 - 300 μm; and / or the inner diameter of the cross-section of the second through-hole is 1 - 10 μm.

4. The MEMS accelerometer device structure according to claim 1, characterized in that, The material of the first hole-sealing layer is any one of silicon dioxide, silicon, or silicon nitride; and / or the material of the second hole-sealing layer is any one of silicon dioxide, silicon, or silicon nitride; and / or the signal-interconnecting wafer includes a plurality of metal layers, and interconnecting via holes are provided between the plurality of metal layers.

5. The preparation method of the MEMS accelerometer device structure according to any one of claims 1 to 4, characterized in that, It includes the following steps: S1. Combine the cover plate with the device layer, and combine the surface of the device layer away from the cover plate with the signal-interconnecting wafer; or combine the device layer with the signal-interconnecting wafer, and combine the surface of the device layer away from the signal-interconnecting wafer with the cover plate; S2. Thinning the cover plate, and etching at least one first through-hole on the thinned cover plate; and / or thinning the signal-interconnecting wafer, and etching at least one second through-hole on the thinned signal-interconnecting wafer; S3. Coating the entire device structure with a hydrophobic material by vapor deposition; S4. Sealing the first through-hole and / or the second through-hole on the device structure obtained in step S3 to obtain an anti-sticking MEMS accelerometer.

6. The preparation method according to claim 5, characterized in that, In step S2, the thickness of the cover plate is thinned to 20 - 300 μm; and / or the thickness of the signal-interconnecting wafer is thinned to 20 - 300 μm.

7. The preparation method according to claim 5, characterized in that In step S2, the inner diameter of the cross-section of the first through-hole is etched to 1 - 10 μm; and / or the inner diameter of the cross-section of the second through-hole is etched to 1 - 10 μm.

8. The preparation method according to claim 5, characterized in that, The method for sealing the first through-hole in step S4 includes: coating a hole-sealing material on the surface of the cover plate facing away from the device layer and / or bonding at least one wafer to obtain a first hole-sealing layer; and / or the method for sealing the second through-hole includes: coating a hole-sealing material on the surface of the signal-interconnecting wafer facing away from the device layer and / or bonding at least one wafer to obtain a second hole-sealing layer.

9. The preparation method according to claim 5, characterized in that, Before plating the hole-sealing material, the hydrophobic material on the surface of the cover plate facing away from the device layer is removed by physical bombardment; and / or the hydrophobic material on the surface of the signal-interconnect wafer facing away from the device layer is removed by physical bombardment.

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