A triaxial MEMS inertial switch and its fabrication method

Abstract

This invention provides a triaxial MEMS inertial switch and its fabrication method, comprising: a substrate having two X-axis electrode groups, two Y-axis electrode groups, and multiple Z-down electrodes thereon; a first movable groove formed by adjacent X-down electrodes and the Z-down electrodes between them; and a second movable groove formed by adjacent Y-down electrodes and the Z-down electrodes between them; a structural layer including a bonding block, a cantilever beam, and a mass block; the bonding block being bonded to the substrate; the cantilever beam connecting the bonding block and the mass block; and the mass block having an upper electrode that can be disposed in either the first or second movable groove, with the upper electrode and the Z-down electrodes spaced apart; and a cover plate having a clearance cavity. This invention employs an electrode surround arrangement and height difference design to achieve physical isolation of the triaxial trigger channels, avoiding signal crosstalk and precisely limiting the displacement of the mass block; the process is simplified and easy to mass-produce, with flexible threshold control; and the cover plate provides sealing protection, improving device reliability and environmental adaptability.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical systems (MEMS), specifically to a triaxial MEMS inertial switch and its fabrication method. Background Technology

[0002] Inertial switches are a type of functional device that uses inertial force (acceleration) as a trigger source to realize the switching of circuits. Their core value lies in the fact that they can respond in real time to specific motion states (such as collisions, impacts, and falls) without continuous power supply, making them indispensable in various safety protection and condition monitoring systems.

[0003] Early inertial switches mostly adopted traditional mechanical structures, with ball bearings, spring contacts, and pendulums as core sensing elements. Their working principle was based on inertial force driving mechanical components to contact or separate to complete circuit switching. Although these mechanical inertial switches were simple in structure and low in cost, they had inherent drawbacks that were difficult to overcome: First, they were large in size and weight, making them unsuitable for the miniaturization needs of modern electronic devices; second, the mechanical contacts were prone to wear and oxidation, resulting in short switch life and insufficient reliability; third, their response speed was slow, making it difficult to meet the triggering requirements of high-speed impact scenarios; and fourth, their mechanical structure had low integration, making it impossible to integrate with integrated circuits (ICs) on-chip or at the system level, limiting their application in complex electronic systems.

[0004] Since the 1990s, with the breakthroughs and maturation of MEMS technology, inertial switches have begun to develop towards chip-level miniaturization. MEMS inertial switches are fabricated using silicon-based micromachining processes, integrating the sensitive structure, electrodes, and support system into a single or multi-chip assembly. They have significant advantages such as small size, mass production capability, easy integration with electronic systems, and low power consumption, and are gradually replacing traditional mechanical switches as the mainstream technology.

[0005] Through gradual development, MEMS inertial switches have evolved from single-axis detection to multi-axis detection, and from passive fixed threshold triggering to intelligent programmable triggering. However, in applications facing high gravitational acceleration and complex vibration environments, existing MEMS inertial switches generally adopt a "single-axis structure superposition" or "asymmetric three-dimensional structure" design. There is mechanical coupling between the sensitive units of the X, Y, and Z axes. When one axis is impacted, it is easy to cause erroneous displacement of the sensitive structures in other axes, resulting in cross-interference and reduced triggering accuracy. However, if the coupling is reduced, there is a problem of uneven sensitivity in the sensitive directions. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problems of low accuracy and uneven sensitivity of existing MEMS inertial switches, and to provide a triaxial MEMS inertial switch and its fabrication method.

[0007] To address the aforementioned technical problems, this invention provides a triaxial MEMS inertial switch, comprising: a substrate, the center of which is a functional region, on which are disposed two X-axis electrode groups, two Y-axis electrode groups, and a plurality of Z-down electrodes arranged around the functional region; the two Y-axis electrode groups are symmetrically arranged along a first direction, and each Y-axis electrode group includes at least three Y-down electrodes spaced apart along a second direction; the two X-axis electrode groups are symmetrically arranged along the second direction, and each X-axis electrode group includes at least three X-down electrodes spaced apart along the first direction; some of the Z-down electrodes are disposed between two adjacent Y-down electrodes, and the remaining Z-down electrodes are disposed between two adjacent X-down electrodes; and the X-down electrodes and the Y-down electrodes protrude beyond the Z-down electrodes in the thickness direction of the substrate, thereby forming a first movable groove through the adjacent X-down electrodes and the Z-down electrodes between them, and through the adjacent X-down electrodes... The Y-axis downward electrode and the Z-axis downward electrode between them form a second movable groove; the structural layer includes a bonding block, a cantilever beam, and a mass block. The bonding block is bonded to the substrate. One end of the cantilever beam is connected to the bonding block, and the other end is connected to the mass block. The mass block has four upper electrode groups on its side facing the substrate. Each upper electrode group includes two upper electrodes that are electrically connected to each other. Two of the upper electrode groups are arranged corresponding to two X-axis electrode groups. The upper electrodes on these groups are all located in the first movable groove, and their corresponding X-axis downward electrodes and Z-axis downward electrodes are spaced apart. The other two upper electrode groups are arranged corresponding to two Y-axis electrode groups. The upper electrodes on these groups are all located in the second movable groove, and their corresponding Y-axis downward electrodes and Z-axis downward electrodes are spaced apart. The cover plate is bonded to the structural layer and has a clearance cavity on its side facing the structural layer for the mass block to move.

[0008] In one embodiment of the present invention, the triaxial MEMS inertial switch further includes an anchor bonding layer, the anchor bonding layer being disposed at the center of the functional area, and the bonding block being bonded to the anchor bonding layer.

[0009] In one embodiment of the present invention, the triaxial MEMS inertial switch further includes a first frame bonding layer, which is disposed around the periphery of the functional area; the structural layer further includes a bonding frame, which is disposed around the periphery of the mass block and bonded to the first frame bonding layer.

[0010] In one embodiment of the present invention, the bonding frame further includes a plurality of limiting blocks, which are disposed on the inner wall of the bonding frame and protrude toward the mass block. The protruding ends of the limiting blocks are spaced apart from the mass block in the horizontal plane to limit the movement distance of the mass block in the horizontal plane.

[0011] In one embodiment of the present invention, the triaxial MEMS inertial switch further includes a second frame bonding layer, the second frame bonding layer being disposed around the avoidance cavity, and the opposite sides of the second frame bonding layer being bonded to the cover plate and the bonding frame, respectively.

[0012] In one embodiment of the present invention, the penetration depth of the upper electrode in its corresponding first or second movable slot is greater than the depth of the avoidance cavity, so as to form a hard limiting structure for the movement of the mass block in a third direction.

[0013] In one embodiment of the present invention, the upper electrode group further includes an electrical connection channel disposed on the surface of the mass block, and the two ends of the electrical connection channel extending in the direction of extension respectively contact the two upper electrodes.

[0014] In one embodiment of the invention, the mass block is configured as a frame structure with the same shape as the functional area, and the structural layer includes four cantilever beams that extend radially toward the four inner walls of the mass block with the mass block as the center.

[0015] In one embodiment of the present invention, the cantilever beams are all configured as a serpentine structure.

[0016] In one embodiment of the present invention, the substrate further includes an X-axis pad, a Y-axis pad, and a Z-axis pad disposed outside the functional area. The plurality of X-axis downward electrodes are electrically connected to the X-axis pad via wires; the plurality of Y-axis downward electrodes are electrically connected to the Y-axis pad via wires; and the plurality of Z-axis downward electrodes are electrically connected to the Z-axis pad via wires.

[0017] This invention also provides a method for fabricating a triaxial MEMS inertial switch, which is used to fabricate the aforementioned triaxial MEMS inertial switch. The method includes: Step S1, fabricating a substrate: After dividing functional regions on a clean silicon substrate, an X-axis electrode group, a Y-axis electrode group, and a Z-axis electrode group are formed in the functional regions. A portion of the Z-axis downward electrodes in the Z-axis electrode group are respectively disposed between two adjacent X-axis downward electrodes in the X-axis electrode group to form a first movable slot. The remaining Z-axis downward electrodes are respectively disposed between two adjacent Y-axis downward electrodes in the Y-axis electrode group to form a second movable slot. S1: Slot; Step S2: Prepare a bonding layer on the substrate; Step S3: Prepare a structural layer: After preparing a bonding block, a cantilever beam, and a mass block on a clean insulating silicon wafer, connect the bonding block to the bonding layer, wherein four upper electrode groups are arranged on the side of the mass block facing the substrate, and the upper electrodes in the upper electrode groups are correspondingly arranged in the first movable slot or the second movable slot; Step S4: Prepare a cover plate: Prepare an avoidance cavity on the side of the clean silicon substrate facing the structural layer; Step S5: Bond the cover plate to the structural layer to obtain the target triaxial MEMS inertial switch.

[0018] In one embodiment of the present invention, step S1 specifically includes: step S11, sputtering a first metal seed layer on a clean silicon substrate; step S12, after spin-coating photoresist on the first metal seed layer for the first time, performing patterning processing for the X-down electrode and the Y-down electrode, then forming the X-down electrode and the Y-down electrode by metal electroplating, and removing the photoresist; step S13, after spin-coating photoresist on the first metal seed layer for the second time, performing patterning processing for the Z-down electrode, and simultaneously performing patterning processing for the X-down electrode, the Y-down electrode, and the Z-down electrode circuit conduction structure on the substrate surface, then removing the remaining positions of the first metal seed layer so that the conductive paths of the X-down electrode, the Y-down electrode, and the Z-down electrode are independent of each other; step S14, after removing the photoresist again, polishing all the surfaces of the bottom electrodes, and cleaning to obtain the target substrate.

[0019] In one embodiment of the present invention, step S2 specifically involves: after spin-coating an adhesive layer on the substrate, performing patterning processing for frame bonding and anchor point bonding, so as to form a first frame bonding layer and an anchor point bonding layer by photolithography.

[0020] In one embodiment of the present invention, step S3 specifically comprises: step S31, sputtering a second metal seed layer onto a clean insulating silicon wafer; step S32, patterning an upper electrode after a first spin-coating of photoresist onto the second metal seed layer, followed by metal electroplating to form the upper electrode, and then removing the photoresist; step S33, patterning an electrical interconnect channel after a second spin-coating of photoresist onto the second metal seed layer, followed by removing the remaining portions of the second metal seed layer to connect the electrical interconnect channel to the upper electrode; step S34, polishing the entire surface of the upper electrode after removing the photoresist again; and step S35, spin-coating photoresist onto the other side of the insulating silicon wafer. After photoresist etching, a pre-defined cavity is patterned, and then infrared deep reactive ion etching is used to etch along the pre-defined pattern to the buried oxide layer of the insulating silicon wafer; Step S36: The insulating silicon wafer is bonded to the first frame bonding layer and the anchor point bonding layer, wherein the bonding frame is bonded to the first frame bonding layer, and the bonding block is bonded to the anchor point bonding layer; Step S37: After spin-coating photolithography from the side of the insulating silicon wafer away from the substrate, the bonding frame, mass block, bonding block and cantilever beam are patterned, and then the bonding frame, the mass block, the bonding block and the cantilever beam are released by deep reactive ion etching to form the target structural layer.

[0021] In one embodiment of the present invention, step S4 specifically involves: spin-coating photoresist onto a clean silicon substrate and then performing patterning processing on the clearance cavity, wherein the photoresist on the outer periphery of the clearance cavity forms a bonding adhesive layer, and the penetration depth of the upper electrode in its corresponding first or second movable groove is greater than the depth of the clearance cavity, so as to form a hard limiting structure for the movement of the mass block in a third direction; in step S5, the cover plate is bonded to the bonding adhesive layer to obtain the target triaxial MEMS inertial switch.

[0022] The technical solution of the present invention has the following advantages compared with the prior art:

[0023] The triaxial MEMS inertial switch and its fabrication method described in this invention employ a surrounding arrangement of X-axis electrode groups, Y-axis electrode groups, and Z-downward electrode in the functional area of ​​the substrate. The Z-downward electrode is embedded between adjacent X-axis and Y-axis electrodes, forming a first and second movable slot that do not interfere with each other. Combined with four corresponding upper electrode groups on the structural layer mass block, this achieves physical isolation and independent layout of the trigger channels in the X±, Y± quadrants and the Z-axis, effectively avoiding signal crosstalk during triggering in different directions and significantly improving the accuracy and signal recognition of triaxial triggering. Simultaneously, utilizing the height difference design where the X-downward and Y-downward electrodes protrude from the Z-downward electrode, the upper electrodes are respectively confined within the first and second movable slots. This provides precise movement guidance for the mass block's translation in the X and Y directions and its lifting in the Z direction, while mechanical limiting prevents excessive displacement of the mass block due to excessive inertial force, reducing the risk of structural collision damage and extending the device's lifespan. Meanwhile, this height difference design, in conjunction with the enclosure structure of the active slot, further enhances the differentiated triggering forms of Z-direction surface contact and X / Y-direction sidewall contact, ensuring the independence and stability of the triggering mechanism in each direction.

[0024] At the process level, this solution uses an integrated photolithography etching process for substrate electrodes and a standardized bonding process for structural layers, eliminating the need for additional complex steps such as silicon bump fabrication and depth calibration. This not only simplifies the process steps and reduces fabrication difficulty and production costs, but also improves the consistency of mass production of devices. Compared with traditional solutions that rely on SOI deep etching depth to control the threshold, this solution offers more flexible threshold control. It can adapt to different threshold acceleration requirements by adjusting structural parameters such as electrode height difference and active slot gap, thus having a wider range of applications and better meeting the needs of different fields.

[0025] In addition, the cover plate avoidance cavity design provides ample space for the mass block to move, avoiding interference between the mass block and the cover plate during the triggering process. At the same time, the sealed cavity structure formed by the cover plate, substrate and structural layer can effectively isolate external dust, moisture and other impurities, reduce the impact of environmental factors on electrode contact performance and structural flexibility, and improve the reliability and stability of the device in harsh environments. Attached Figure Description

[0026] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0027] Figure 1 This is a three-dimensional structural schematic diagram of a triaxial MEMS inertial switch in a preferred embodiment of the present invention;

[0028] Figure 2 yes Figure 1A three-dimensional structural diagram of the cover plate in the triaxial MEMS inertial switch shown.

[0029] Figure 3 yes Figure 1 A three-dimensional structural diagram of the substrate and structural layers in a triaxial MEMS inertial switch is shown.

[0030] Figure 4 yes Figure 3 Top view of the substrate and structural layers shown;

[0031] Figure 5 yes Figure 4 Schematic diagram of the cross-sectional structure at point AA;

[0032] Figure 6 yes Figure 5 Enlarged structural diagram at point B;

[0033] Figure 7 yes Figure 1 A three-dimensional structural diagram of the structural layer in the triaxial MEMS inertial switch shown.

[0034] Figure 8 yes Figure 1 A three-dimensional structural diagram of the substrate, the first frame bonding layer, and the anchor point bonding layer in the triaxial MEMS inertial switch shown.

[0035] Figure 9 yes Figure 1 The surface structure diagram of the substrate in the triaxial MEMS inertial switch is shown.

[0036] Explanation of reference numerals in the accompanying drawings: 100, substrate; 110, X-axis electrode group; 111, X-axis downward electrode; 112, X-axis pad; 120, Y-axis electrode group; 121, Y-axis downward electrode; 122, Y-axis pad; 130, Z-axis downward electrode; 131, Z-axis pad; 200, first frame bonding layer; 300, anchor point bonding layer; 400, structural layer; 410, bonding frame; 411, limiting block; 420, mass block; 430, bonding block; 440, cantilever beam; 450, upper electrode group; 451, upper electrode; 452, electrical connection channel; 500, cover plate; 510, clearance cavity; 600, second frame bonding layer; X, first direction; Y, second direction; Z, third direction. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0038] Example 1: See Figures 1 to 9As shown, this embodiment provides a triaxial MEMS inertial switch, which includes: a substrate 100, the center of which is a functional area, on which are disposed two X-axis electrode groups 110, two Y-axis electrode groups 120, and a plurality of Z-down electrodes 130 arranged around the functional area. The two Y-axis electrode groups 120 are symmetrically arranged along a first direction X, and any Y-axis electrode group 120 includes at least three Z-down electrodes 121 spaced apart along a second direction Y; the two X-axis electrode groups 110 are symmetrically arranged along the second direction Y, and any X-axis electrode group 110 includes at least three Z-down electrodes 130 spaced apart along the first direction Y. The X-down electrodes 111 are arranged at X-intervals. A portion of the Z-down electrodes 130 are disposed between two adjacent Y-down electrodes 121, while the remaining Z-down electrodes 130 are disposed between two adjacent X-down electrodes 111. The X-down electrodes 111 and the Y-down electrodes 121 protrude beyond the Z-down electrodes 130 in the thickness direction of the substrate 100, thereby forming a first movable groove between adjacent X-down electrodes 111 and the Z-down electrodes 130 between them. A second movable groove is formed around the electrode 130; a structural layer 400 includes a bonding block 430, a cantilever beam 440, and a mass block 420. The bonding block 430 is bonded to the substrate 100. One end of the cantilever beam 440 is connected to the bonding block 430, and the other end is connected to the mass block 420. The mass block 420 has four upper electrode groups 450 on the side facing the substrate 100. Each upper electrode group 450 includes two interconnected upper electrodes 451. Two upper electrode groups 450 are arranged corresponding to two X-axis electrode groups 110. The upper electrodes 451 are all disposed in the first movable groove, and the X downward electrode 111 and the Z downward electrode 130 corresponding to them are spaced apart; the other two upper electrode groups 450 are disposed corresponding to the two Y-axis electrode groups 120, and the upper electrodes 451 on them are all disposed in the second movable groove, and the Y downward electrode 121 and the Z downward electrode 130 corresponding to them are spaced apart; the cover plate 500 is bonded to the structural layer 400, and the cover plate 500 has a clearance cavity 510 on the side facing the structural layer 400 for the mass block 420 to move.

[0039] It should be noted that, for ease of description, in this embodiment, the length direction of the triaxial MEMS inertial switch is defined as the first direction X, the width direction of the triaxial MEMS inertial switch is defined as the second direction Y, and the thickness direction of the triaxial MEMS inertial switch is defined as the third direction Z. The first direction X, the second direction Y, and the third direction Z are arranged perpendicularly to each other, and the first direction X and the second direction Y are located in the same plane.

[0040] In this embodiment, the substrate 100 serves as the basic support structure for the entire switch. Its core function is to provide stable support for the bonding of the subsequent structural layer 400, and to conduct trigger signals through the surface-integrated electrode group in cooperation with the electrodes 451 on the structural layer 400. The functional area at the center of the substrate 100 is the core area for triaxial triggering, and all electrode groups are arranged around this area to ensure that the movement of the mass block 420 of the structural layer 400 precisely corresponds to the electrodes.

[0041] Furthermore, the functional area in this embodiment is preferably a rectangular area. On the one hand, the regular shape of the rectangle precisely matches the vertically symmetrical arrangement of the X-axis electrode group 110 and the Y-axis electrode group 120, allowing the first and second movable slots to extend uniformly along the corresponding directions, providing a balanced space for the movement of the upper electrode group 450. On the other hand, the clear and controllable rectangular boundary can precisely limit the range of motion of the mass block 420, ensuring uniform trigger thresholds in each direction and avoiding damage from excessive displacement. Thirdly, the photolithography preparation precision of the rectangular pattern is easy to control, which can improve the consistency of electrode group preparation and reduce process errors and production costs. Fourthly, it is convenient to adapt to the contour of the rectangular mass block 420, improving the alignment accuracy between the upper electrode group 450 and the movable slot.

[0042] Furthermore, the two X-axis electrode groups 110 and the two Y-axis electrode groups 120 are key conductive structures for achieving horizontal (X±, Y±) triggering. They are arranged symmetrically: the two Y-axis electrode groups 120 are symmetrically arranged along the first direction X, with each group having at least three Y-down electrodes 121 spaced apart along the second direction Y. This arrangement ensures that when the mass block 420 translates in the Y± direction, the upper electrode 451 can stably form contact with the corresponding Y-down electrode 121. Similarly, the two X-axis electrode groups 110 are symmetrically arranged along the second direction Y, with each group having at least three X-down electrodes 111 spaced apart along the first direction X, thus ensuring the stability of X± direction triggering. Multiple Z-down electrodes 130 are embedded between adjacent X-down electrodes 111 and adjacent Y-down electrodes 121, specifically adapted to Z-direction Z-triggering requirements, forming a conductive pairing with the upper electrode 451 of the structural layer 400 for Z-direction Z-triggering.

[0043] Crucially, the X-down electrode 111 and Y-down electrode 121 protrude beyond the Z-down electrode 130 in the thickness direction of the substrate 100. This height difference design, on the one hand, can create a first movable groove (enclosed by adjacent X-down electrodes 111 and the middle Z-down electrode 130) and a second movable groove (enclosed by adjacent Y-down electrodes 121 and the middle Z-down electrode 130), providing precise guiding space for the upper electrode 451 of the structural layer 400 and avoiding interference when moving in different directions; on the other hand, the height difference clarifies the trigger contact form, ensuring that the upper electrode 451 is in close contact with the electrode sidewall in the X / Y direction, and in the Z direction, the upper electrode 451 is in surface contact with the electrode surface, ensuring the independence of the triggering mechanism in each direction.

[0044] Specifically, the substrate 100 further includes an X-axis pad 112, a Y-axis pad 122, and a Z-axis pad 131 disposed outside the functional area. The plurality of X-axis downward electrodes 111 are electrically connected to the X-axis pad 112 via wires; the plurality of Y-axis downward electrodes 121 are electrically connected to the Y-axis pad 122 via wires; and the plurality of Z-axis downward electrodes 130 are electrically connected to the Z-axis pad 131 via wires. The pad layout outside the functional area avoids the pads occupying the core trigger space and interfering with the activity of the mass block 420. It can also form an independent conductive loop with the corresponding electrode group through the wires, so that the trigger signals of X±, Y± and Z direction can be transmitted to the external detection circuit through X direction pad 112, Y direction pad 122 and Z direction pad 131 respectively, realizing independent acquisition and identification of three-axis trigger signals. At the same time, the clear correspondence between the classified pads and wires can effectively avoid crosstalk between signals in different directions, improve the stability and accuracy of signal transmission, and this layout is highly compatible with the photolithography and etching process of the substrate 100. The fabrication of wires and pads can be completed at the same time as electrode patterning, simplifying the overall process steps.

[0045] In this embodiment, the structural layer 400 is the core component that senses external acceleration and drives the trigger action. It consists of a bonding block 430, a cantilever beam 440, a mass block 420, and an upper electrode assembly 450. These components work together to achieve the trigger conversion between force, displacement, and electrical contact. The core function of the bonding block 430 is to achieve a stable connection between the structural layer 400 and the substrate 100. By bonding with the substrate 100, it fixes the entire structural layer 400 to a preset position on the substrate 100, while providing a fixed support point for the cantilever beam 440, ensuring that the cantilever beam 440 can drive the mass block 420 to move stably.

[0046] In this embodiment, the triaxial MEMS inertial switch further includes an anchor bonding layer 300, which is disposed at the center of the functional area. The bonding block 430 is bonded to the anchor bonding layer 300. The anchor bonding layer 300 is the core intermediary structure for achieving a precise and stable connection between the structural layer 400 and the substrate 100. Its placement at the center of the functional area allows it to form symmetrical force support points with the bonding block 430 of the structural layer 400, ensuring uniform force at the bonding point when the cantilever beam 440 moves the mass block 420. This prevents the bonding between the structural layer 400 and the substrate 100 from failing or detaching due to excessive force on one side. Meanwhile, the presence of the anchor bonding layer 300 can help regulate the initial gap between the mass block 420 of the structural layer 400 and the electrode of the substrate 100 by precisely controlling its own thickness, thereby further optimizing the trigger threshold accuracy of the switch. Moreover, the anchor bonding layer 300 can be formed using the same BCB adhesive material and photolithography patterning process as the bonding frame 410 in the substrate 100 fabrication process, without the need for additional processing steps. It is highly compatible with the overall process, which not only improves the reliability of the structural connection but also simplifies the device fabrication process.

[0047] In this embodiment, the cantilever beam 440 serves as an elastic connection structure, undertaking the dual functions of elastic reset and displacement transmission: when an external acceleration is applied, the cantilever beam 440 undergoes elastic deformation, causing the mass block 420 to displace along the acceleration direction; when the acceleration disappears, the cantilever beam 440 relies on its own elastic restoring force to reset the mass block 420, ensuring that the switch returns to its initial normally open state. Specifically, the mass block 420 is configured as a frame structure with the same shape as the functional area, and the structural layer 400 includes four cantilever beams 440. The four cantilever beams 440 extend radially toward the four inner walls of the mass block 420 with the mass block 420 as the center, and each cantilever beam 440 is configured as a serpentine structure.

[0048] Among them, the mass block 420 is the core sensitive component of the structural layer 400. It has a certain mass and can generate inertial force under the action of external acceleration, thereby driving itself to translate (X / Y direction) or rise and fall (Z direction) along the acceleration direction. At the same time, the four upper electrode groups 450 arranged on the side of the mass block 420 facing the substrate 100 are the core conductive structures for trigger signal transmission, and form a one-to-one correspondence with the electrode groups of the substrate 100: the upper electrode groups 450 of the two corresponding X-direction electrode groups 110 are embedded in the first movable slot, maintaining an initial distance from the X-down electrode 111 and the Z-down electrode 130, ensuring that they can accurately contact the X-down electrode 111 when triggered in the X± direction; the other two upper electrode groups 450 of the two corresponding Y-direction electrode groups 120 are embedded in the second movable slot, maintaining an initial distance from the Y-down electrode 121 and the Z-down electrode 130, ensuring accurate contact when triggered in the Y± direction; and the two upper electrodes 451 in each upper electrode group 450 are electrically connected to each other, forming a complete conductive circuit, ensuring that the signal can be stably transmitted when triggered, realizing the switch closure. The frame structure mass block 420, which is identical in shape to the functional area, can form a precise spatial fit with the first and second movable slots on the substrate 100. This maximizes the use of the movable space within the functional area and avoids the mass block 420 from rubbing against the surrounding electrodes during X / Y translation or Z-axis lifting and lowering through the regular contour of the frame, thus ensuring the smoothness of the triggering action.

[0049] The layout of four cantilever beams 440 radiating outwards towards the four inner walls of the mass block 420 provides all-around, symmetrical elastic support for the mass block 420. This ensures that the mass block 420 receives balanced elastic recovery force under force in any direction, effectively preventing movement deviation or jamming caused by force imbalance and ensuring accurate reset after triggering. The serpentine structure of the cantilever beams 440 further optimizes elastic performance. Compared to a straight beam structure, its bent shape extends the force transmission path, allowing for greater elastic deformation under the same inertial force. This gives the mass block 420 a larger stroke, adapting to triggering requirements with different threshold accelerations. Simultaneously, the serpentine structure possesses superior fatigue resistance, effectively reducing structural damage caused by repeated deformation of the cantilever beams 440 and significantly extending the device's lifespan. Furthermore, this cantilever beam 440 layout and the frame structure of the mass block 420 can be formed through a single photolithography and etching process, highly compatible with the overall micro-nano fabrication process, which is beneficial for improving consistency and yield in mass production.

[0050] Specifically, the upper electrode group 450 in this embodiment further includes an electrical connection channel 452. The electrical connection channel 452 is disposed on the surface of the mass block 420, and its two ends in the extending direction respectively contact the two upper electrodes 451. This electrical connection channel 452 is the core structure for realizing the electrical conduction of the two upper electrodes 451 within the same upper electrode group 450. Its design, which is directly integrated into the surface of the mass block 420, can maintain a stable electrical connection between the two upper electrodes 451 as the mass block 420 moves with external acceleration, ensuring that the two upper electrodes 451 within the same electrode group can synchronously transmit trigger signals and avoid signal disconnection caused by electrode separation. Meanwhile, the electrical connection channel 452 and the upper electrode 451 can be integrally formed using the same metal fabrication process, eliminating the need for additional lead connection structures. This simplifies the processing of the structural layer 400 and reduces the space occupied by redundant structures on the mass block 420, ensuring the flexibility of the mass block 420's movement. Furthermore, the width and thickness of the electrical connection channel 452 can be precisely controlled through photolithography and electroplating processes, adapting to the miniaturization design requirements of MEMS devices and further improving the stability and reliability of the electrode group's signal transmission.

[0051] In this embodiment, the triaxial MEMS inertial switch further includes a first frame bonding layer 200, which is disposed around the periphery of the functional area; the structural layer 400 further includes a bonding frame 410, which is disposed around the mass block 420 and bonded to the first frame bonding layer 200. This design forms a dual fixing structure through the peripheral frame bonding and the central anchor point bonding layer 300, which greatly improves the stability of the connection between the structural layer 400 and the substrate 100: the first frame bonding layer 200 is arranged around the periphery of the functional area, and together with the bonding frame 410 around the structural layer 400, it forms an annular sealed bonding area. This avoids the bonding structure occupying the core trigger space, and can also evenly distribute the load-bearing pressure of the structural layer 400 through the annular force distribution, preventing connection failure caused by force concentration in a single anchor point bonding. At the same time, the annular bonding area can also enhance the sealing performance of the device, further isolating external dust, moisture and other impurities from eroding the internal electrodes and moving structures. Furthermore, the cooperation between the bonding frame 410 and the first frame bonding layer 200 can help calibrate the alignment accuracy between the structural layer 400 and the substrate 100, ensuring that the electrode group 450 on the mass block 420 can be accurately embedded in the first and second movable slots of the substrate 100, thus ensuring the accuracy of triggering. Moreover, both can be formed using the same BCB adhesive and photolithography process as the center anchor bonding layer 300, without the need for additional processing steps. This is highly compatible with the overall fabrication process, effectively controlling production difficulty and cost while improving structural reliability.

[0052] Furthermore, the bonding frame 410 also includes a plurality of limiting blocks 411. These limiting blocks 411 are disposed on the inner wall of the bonding frame 410 and protrude towards the mass block 420. The protruding ends of the limiting blocks 411 are spaced apart from the mass block 420 in the horizontal plane to limit the movement distance of the mass block 420 in the horizontal plane. The multiple limiting blocks 411 are evenly distributed along the inner wall of the bonding frame 410, protruding towards the mass block 420 and maintaining a reasonable interval. This arrangement does not affect the normal translation (X±, Y± directions) of the mass block 420 within the trigger threshold range, and can precisely limit the maximum movement distance of the mass block 420 through physical obstruction when external acceleration is excessive, preventing it from violently colliding with surrounding electrodes and bonding structures due to excessive inertial force, thus avoiding structural damage such as electrode deformation and cantilever beam 440 breakage. Meanwhile, the limiting block 411 and the bonding frame 410 adopt an integrated structural design, which can be formed by the same photolithography and etching process without the need for additional processing steps, and is highly compatible with the overall micro-nano processing flow; moreover, the protrusion height and spacing distance of the limiting block 411 can be precisely controlled by the photolithography process, and can be flexibly adapted to different threshold acceleration requirements, further improving the stability and service life of the device.

[0053] In this embodiment, the cover plate 500 is bonded to the structural layer 400 to form the encapsulation structure of the entire switch. Its core function is to provide protection and limit the movement of the moving parts of the structural layer 400. The avoidance cavity 510 provided on the side of the cover plate 500 facing the structural layer 400 provides sufficient space for the movement of the mass block 420, which can prevent the mass block 420 from colliding and interfering with the cover plate 500 during X / Y translation or Z-axis lifting, ensuring that the triggering action can be completed smoothly. At the same time, the sealed cavity formed by the cover plate 500, the substrate 100, and the structural layer 400 can effectively isolate dust, moisture and other impurities in the external environment, reduce the impact of impurities on electrode contact performance and structural flexibility, and improve the reliability and service life of the device in harsh environments.

[0054] Furthermore, the triaxial MEMS inertial switch also includes a second frame bonding layer 600. The second frame bonding layer 600 is disposed around the clearance cavity 510, and the opposite sides of the second frame bonding layer 600 are respectively bonded to the cover plate 500 and the bonding frame 410. The second frame bonding layer 600 is the core intermediary structure for achieving a stable encapsulation between the cover plate 500 and the structural layer 400. Its annular layout around the clearance cavity 510 can form a precise surface contact bond with the bonding frame 410 of the structural layer 400, constructing a full circumferential sealed connection from the substrate 100, the structural layer 400 to the cover plate 500, further enhancing the sealing performance of the device, effectively isolating external dust, moisture, corrosive gases and other impurities from intruding into the internal core area, and preventing impurities from affecting the reliability of electrode contact and the mobility of the cantilever beam 440 and the mass block 420. Meanwhile, the annular second frame bonding layer 600 can evenly distribute the force between the cover plate 500 and the bonding frame 410, preventing bonding failure caused by localized force concentration and ensuring the long-term stability of the packaging structure. Together with the first frame bonding layer 200 and the central anchor bonding layer 300, it forms a multi-layered three-dimensional fixing system, further enhancing the structural rigidity of the entire device and reducing the interference of environmental vibrations on the internal triggering structure. Furthermore, the second frame bonding layer 600 can be fabricated using the same materials (such as BCB adhesive) and photolithography patterning process as other bonding layers, requiring no additional processing steps. It is highly compatible with the overall micro / nano fabrication process, effectively controlling fabrication costs and process complexity while improving packaging reliability.

[0055] It should be noted that in this embodiment, the penetration depth of the upper electrode 451 in its corresponding first or second movable slot is greater than the depth of the avoidance cavity 510, so as to form a hard limiting structure for the movement of the mass block 420 in the third direction Z. This design constructs a reliable limiting mechanism in the third direction Z through precise size adaptation. When the mass block 420 moves upward or downward under the action of Z-axis acceleration, the difference between the penetration depth of the upper electrode 451 and the depth of the avoidance cavity 510 forms a clear upper limit of displacement. Once the mass block 420 moves to the limit position, the upper electrode 451 will form rigid contact with the inner wall of the movable slot or the cover plate 500, terminating the displacement through physical blocking, and avoiding structural failure problems such as elastic fatigue fracture of the cantilever beam 440 and electrode collision damage caused by excessive movement. Meanwhile, this hard-limiting structure does not require additional independent limiting components. It directly utilizes the size difference between the upper electrode 451 and the movable groove and the avoidance cavity 510 to achieve the function, simplifying the structural design. Moreover, the limiting stroke can be precisely controlled by photolithography and etching processes to adjust the penetration depth of the upper electrode 451 and the depth of the avoidance cavity 510. This allows for flexible adaptation to different Z-axis Z-threshold acceleration design requirements, further improving the stability and lifespan of the device's Z-axis Z-triggering.

[0056] Example 2: This example provides a method for fabricating a triaxial MEMS inertial switch, which is used to fabricate the triaxial MEMS inertial switch described in Example 1, and includes:

[0057] Step S1: Substrate fabrication: After dividing functional regions on a clean silicon substrate, X-axis electrode groups, Y-axis electrode groups, and Z-axis electrode groups are formed in the functional regions. Some of the Z-axis downward electrodes in the Z-axis electrode group are respectively disposed between two adjacent X-axis downward electrodes in the X-axis electrode group to form a first movable groove. The remaining Z-axis downward electrodes are respectively disposed between two adjacent Y-axis downward electrodes in the Y-axis electrode group to form a second movable groove.

[0058] Furthermore, step S1 specifically includes:

[0059] Step S11: Sputter a first metal seed layer onto a clean silicon substrate;

[0060] Step S12: After spin-coating photoresist onto the first metal seed layer for the first time, patterning of the X-down electrode and the Y-down electrode is performed. Then, the X-down electrode and the Y-down electrode are formed by metal electroplating, and the photoresist is removed.

[0061] Step S13: After spin-coating photoresist a second time on the first metal seed layer, perform patterning processing of the Z-down electrode. At the same time, perform patterning processing of the X-down electrode, Y-down electrode and Z-down electrode circuit conduction structure on the substrate surface. Then remove the remaining parts of the first metal seed layer so that the conductive paths of the X-down electrode, Y-down electrode and Z-down electrode are independent of each other.

[0062] Step S14: After removing the photoresist again, polish all the surfaces of the lower electrode and clean them to obtain the target substrate.

[0063] Step S2: Prepare a bonding layer on the substrate. Specifically, step S2 involves: after spin-coating an adhesive layer on the substrate, performing patterning processing for frame bonding and anchor point bonding, so as to form a first frame bonding layer and an anchor point bonding layer through photolithography.

[0064] Step S3: Fabrication of the structural layer: After fabricating a bonding block, a cantilever beam, and a mass block on a clean insulating silicon wafer, the bonding block is connected to the bonding layer. Four upper electrode groups are disposed on the side of the mass block facing the substrate, and the upper electrodes in the upper electrode groups are correspondingly disposed in the first or second movable slot. Further, step S3 specifically involves:

[0065] Step S31: Sputter a second metal seed layer onto a clean insulating silicon wafer;

[0066] Step S32: After spin-coating photoresist onto the second metal seed layer for the first time, the upper electrode is patterned, and then the upper electrode is formed by metal electroplating and the photoresist is removed.

[0067] Step S33: After spin-coating photoresist a second time on the second metal seed layer, perform patterning processing of the electrical connection channel, and then remove the remaining parts of the second metal seed layer so that the electrical connection channel is connected to the upper electrode.

[0068] Step S34: After removing the photoresist again, polish all the surfaces of the upper electrode.

[0069] Step S35: After spin-coating photoresist on the other side of the insulating silicon wafer, perform patterning of the preset cavity, and then use infrared deep reactive ion etching to etch along the preset pattern to the buried oxide layer of the insulating silicon wafer.

[0070] Step S36: Bond the insulating silicon wafer to the first frame bonding layer and the anchor point bonding layer, wherein the bonding frame is bonded to the first frame bonding layer and the bonding block is bonded to the anchor point bonding layer.

[0071] Step S37: After spin-coating photolithography on the side of the insulating silicon wafer away from the substrate, patterning of the bonding frame, mass block, bonding block and cantilever beam is performed. Then, the bonding frame, mass block, bonding block and cantilever beam are obtained by deep reactive ion etching to form the target structural layer.

[0072] Step S4: Fabrication of the cover plate: A clearance cavity is fabricated on the side of a clean silicon substrate facing the structural layer. Specifically, step S4 involves: spin-coating photoresist onto a clean silicon substrate and then patterning the clearance cavity. The photoresist on the outer periphery of the clearance cavity forms a bonding adhesive layer, and the penetration depth of the upper electrode in its corresponding first or second movable groove is greater than the depth of the clearance cavity, so as to form a hard limiting structure for the movement of the mass block in a third direction.

[0073] Step S5: Bond the cover plate to the structural layer, specifically by bonding the cover plate to the bonding adhesive layer to obtain the target triaxial MEMS inertial switch.

[0074] In summary, the triaxial MEMS inertial switch and its fabrication method described in this invention employ a surrounding arrangement of X-axis electrode groups, Y-axis electrode groups, and Z-downward electrode in the functional area of ​​the substrate, with the Z-downward electrode embedded between adjacent X-axis and Y-axis electrodes to form a first and second movable slot that do not interfere with each other. Combined with the four upper electrode groups correspondingly arranged on the structural layer mass block, this achieves physical isolation and independent layout of the trigger channels in the X±, Y± quadrants and the Z-axis, effectively avoiding signal crosstalk during triggering in different directions and significantly improving the accuracy and signal recognition of triaxial triggering. Simultaneously, utilizing the height difference design where the X-downward and Y-downward electrodes protrude from the Z-downward electrode, the upper electrodes are respectively confined within the first and second movable slots. This provides precise movement guidance for the mass block's translation in the X and Y directions and its lifting in the Z direction, while mechanical limiting prevents excessive displacement of the mass block due to excessive inertial force, reducing the risk of structural collision damage and extending the device's lifespan. Meanwhile, this height difference design, in conjunction with the enclosure structure of the active slot, further enhances the differentiated triggering forms of Z-direction surface contact and X / Y-direction sidewall contact, ensuring the independence and stability of the triggering mechanism in each direction.

[0075] At the process level, this solution uses an integrated photolithography etching process for substrate electrodes and a standardized bonding process for structural layers, eliminating the need for additional complex steps such as silicon bump fabrication and depth calibration. This not only simplifies the process steps and reduces fabrication difficulty and production costs, but also improves the consistency of mass production of devices. Compared with traditional solutions that rely on SOI deep etching depth to control the threshold, this solution offers more flexible threshold control. It can adapt to different threshold acceleration requirements by adjusting structural parameters such as electrode height difference and active slot gap, thus having a wider range of applications and better meeting the needs of different fields.

[0076] In addition, the cover plate avoidance cavity design provides ample space for the mass block to move, avoiding interference between the mass block and the cover plate during the triggering process. At the same time, the sealed cavity structure formed by the cover plate, substrate and structural layer can effectively isolate external dust, moisture and other impurities, reduce the impact of environmental factors on electrode contact performance and structural flexibility, and improve the reliability and stability of the device in harsh environments.

[0077] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A triaxial MEMS inertial switch, characterized in that: include: A substrate, the center of which is a functional area, is provided with two X-axis electrode groups, two Y-axis electrode groups, and multiple Z-down electrodes arranged around the functional area. The two Y-axis electrode groups are symmetrically arranged along a first direction, and each Y-axis electrode group includes at least three Y-down electrodes spaced apart along a second direction. The two X-axis electrode groups are symmetrically arranged along the second direction, and each X-axis electrode group includes at least three X-down electrodes spaced apart along the first direction. Some of the Z-down electrodes are respectively disposed between two adjacent X-down electrodes, and the remaining Z-down electrodes are respectively disposed between two adjacent Y-down electrodes. The X-down electrodes and the Y-down electrodes protrude from the Z-down electrodes in the thickness direction of the substrate, so as to form a first movable groove through the adjacent X-down electrodes and the Z-down electrodes between them, and to form a second movable groove through the adjacent Y-down electrodes and the Z-down electrodes between them. The structural layer includes a bonding block, a cantilever beam, and a mass block. The bonding block is bonded to the substrate. One end of the cantilever beam is connected to the bonding block, and the other end is connected to the mass block. The mass block has four upper electrode groups on the side facing the substrate. Each upper electrode group includes two electrically connected upper electrodes. Two upper electrode groups are arranged corresponding to two X-axis electrode groups, and the upper electrodes on them are all disposed in the first movable slot, with their corresponding X-down and Z-down electrodes spaced apart. The other two upper electrode groups are arranged corresponding to two Y-axis electrode groups, and the upper electrodes on them are all disposed in the second movable slot, with their corresponding Y-down and Z-down electrodes spaced apart. A cover plate, which is bonded to the structural layer, has a clearance cavity on one side facing the structural layer for the mass block to move.

2. The triaxial MEMS inertial switch according to claim 1, characterized in that: The triaxial MEMS inertial switch further includes an anchor bonding layer, which is disposed at the center of the functional area, and the bonding block is bonded to the anchor bonding layer.

3. The triaxial MEMS inertial switch according to claim 1, characterized in that: The triaxial MEMS inertial switch further includes a first frame bonding layer, which is disposed around the periphery of the functional area; the structural layer further includes a bonding frame, which is disposed around the periphery of the mass block and bonded to the first frame bonding layer.

4. The triaxial MEMS inertial switch according to claim 3, characterized in that: The bonding frame further includes multiple limiting blocks, which are disposed on the inner wall of the bonding frame and protrude toward the mass block. The protruding ends of the limiting blocks are spaced apart from the mass block in the horizontal plane to limit the movement distance of the mass block in the horizontal plane.

5. The triaxial MEMS inertial switch according to claim 1, characterized in that: The triaxial MEMS inertial switch further includes a second frame bonding layer, which is disposed around the avoidance cavity, and the opposite sides of the second frame bonding layer are respectively bonded to the cover plate and the bonding frame.

6. The triaxial MEMS inertial switch according to claim 1, characterized in that: The penetration depth of the upper electrode in its corresponding first or second movable slot is greater than the depth of the avoidance cavity, so as to form a hard limiting structure for the movement of the mass block in the third direction.

7. The triaxial MEMS inertial switch according to claim 1, characterized in that: The upper electrode assembly further includes an electrical connection channel, which is disposed on the surface of the mass block, and the two ends of the electrical connection channel extending in the direction of extension respectively contact the two upper electrodes.

8. The triaxial MEMS inertial switch according to claim 1, characterized in that: The mass block is configured as a frame structure with the same shape as the functional area. The structural layer includes four cantilever beams that extend radially toward the four inner walls of the mass block with the mass block as the center.

9. The triaxial MEMS inertial switch according to claim 1 or 8, characterized in that: All cantilever beams are configured with a serpentine structure.

10. The triaxial MEMS inertial switch according to claim 1, characterized in that: The substrate further includes X-axis pads, Y-axis pads, and Z-axis pads disposed outside the functional area. The plurality of X-axis downward electrodes are electrically connected to the X-axis pads via wires; the plurality of Y-axis downward electrodes are electrically connected to the Y-axis pads via wires; and the plurality of Z-axis downward electrodes are electrically connected to the Z-axis pads via wires.

11. A method for fabricating a triaxial MEMS inertial switch, characterized in that: The method for fabricating the triaxial MEMS inertial switch according to any one of claims 1 to 10 comprises: Step S1: Substrate preparation: After dividing functional regions on a clean silicon substrate, X-axis electrode group, Y-axis electrode group and Z-axis electrode group are formed in the functional regions. Some of the Z-axis downward electrodes in the Z-axis electrode group are respectively disposed between two adjacent X-axis downward electrodes in the X-axis electrode group to form a first movable groove. The remaining Z-axis downward electrodes are respectively disposed between two adjacent Y-axis downward electrodes in the Y-axis electrode group to form a second movable groove. Step S2: Prepare a bonding layer on the substrate; Step S3: Fabrication of structural layer: After fabricating bonding block, cantilever beam and mass block on clean insulating silicon wafer, the bonding block is connected to the bonding layer. The mass block is provided with four upper electrode groups on the side facing the substrate, and the upper electrodes in the upper electrode groups are correspondingly disposed in the first movable groove or the second movable groove. The structural layer also includes a bonding frame, which is disposed around the mass block and bonded to the first frame bonding layer. Step S4: Prepare the cover plate: Prepare an avoidance cavity on the side of a clean silicon substrate facing the structural layer; Step S5: Bond the cover plate to the structural layer to obtain the target triaxial MEMS inertial switch.

12. The method for fabricating a triaxial MEMS inertial switch according to claim 11, characterized in that: Step S1 specifically includes: Step S11: Sputter a first metal seed layer onto a clean silicon substrate; Step S12: After spin-coating photoresist onto the first metal seed layer for the first time, patterning of the X-down electrode and the Y-down electrode is performed. Then, the X-down electrode and the Y-down electrode are formed by metal electroplating, and the photoresist is removed. Step S13: After spin-coating photoresist a second time on the first metal seed layer, perform patterning processing of the Z-down electrode. At the same time, perform patterning processing of the X-down electrode, Y-down electrode and Z-down electrode circuit conduction structure on the substrate surface. Then remove the remaining parts of the first metal seed layer so that the conductive paths of the X-down electrode, Y-down electrode and Z-down electrode are independent of each other. Step S14: After removing the photoresist again, polish all the surfaces of the lower electrode and clean them to obtain the target substrate.

13. The method for fabricating a triaxial MEMS inertial switch according to claim 11, characterized in that: Step S2 specifically involves: after spin-coating the adhesive layer on the substrate, performing patterning processing for frame bonding and anchor point bonding, so as to form the first frame bonding layer and anchor point bonding layer through photolithography.

14. The method for fabricating a triaxial MEMS inertial switch according to claim 13, characterized in that: Step S3 is as follows: Step S31: Sputter a second metal seed layer onto a clean insulating silicon wafer; Step S32: After spin-coating photoresist onto the second metal seed layer for the first time, the upper electrode is patterned, and then the upper electrode is formed by metal electroplating and the photoresist is removed. Step S33: After spin-coating photoresist a second time on the second metal seed layer, perform patterning processing of the electrical connection channel, and then remove the remaining parts of the second metal seed layer so that the electrical connection channel is connected to the upper electrode. Step S34: After removing the photoresist again, polish all the surfaces of the upper electrode. Step S35: After spin-coating photoresist on the other side of the insulating silicon wafer, perform patterning of the preset cavity, and then use infrared deep reactive ion etching to etch along the preset pattern to the buried oxide layer of the insulating silicon wafer. Step S36: Bond the insulating silicon wafer to the first frame bonding layer and the anchor point bonding layer, wherein the bonding frame is bonded to the first frame bonding layer and the bonding block is bonded to the anchor point bonding layer. Step S37: After spin-coating photolithography on the side of the insulating silicon wafer away from the substrate, patterning of the bonding frame, mass block, bonding block and cantilever beam is performed. Then, the bonding frame, mass block, bonding block and cantilever beam are obtained by deep reactive ion etching to form the target structural layer.

15. The method for fabricating a triaxial MEMS inertial switch according to claim 11, characterized in that: Step S4 specifically involves: spin-coating photoresist onto a clean silicon substrate and then performing patterning of the clearance cavity. The photoresist on the outer periphery of the clearance cavity forms a bonding adhesive layer, and the penetration depth of the upper electrode in its corresponding first or second movable groove is greater than the depth of the clearance cavity, so as to form a hard limiting structure for the movement of the mass block in the third direction. In step S5, the cover plate is bonded to the bonding adhesive layer to obtain the target triaxial MEMS inertial switch.

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