Acceleration sensor manufacturing method and acceleration sensor

Abstract

The application relates to the technical field of micro electromechanical systems, in particular to a preparation method of an acceleration sensor and the acceleration sensor. The method comprises the following steps: sequentially depositing a first sacrificial layer and a first structure layer serving as a fixed electrode on a substrate surface; performing patterned etching on the first structure layer to form a protection structure; depositing a second sacrificial layer on the surface of the first structure layer; performing etching on the surface of the second sacrificial layer to form a groove with a depth smaller than the thickness of the second sacrificial layer; depositing a second structure layer serving as a mass block electrode on the surface of the second sacrificial layer; performing patterned etching on the second structure layer to form a stop structure; the projection of the stop structure and the protection structure on the substrate at least partially overlaps; and releasing the first sacrificial layer and the second sacrificial layer. The application can form the protection structure and the stop structure while preparing the electrode, thereby improving the processing efficiency, shortening the preparation period and effectively reducing the manufacturing cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-electro-mechanical systems, and in particular, to a method for manufacturing an acceleration sensor and an acceleration sensor. BACKGROUND

[0002] In the field of micro-electro-mechanical systems (MEMS), Z-axis high-g acceleration sensors are widely used in environments that need to withstand large impacts and high vibrations. The core function of the Z-axis high-g acceleration sensor is to perceive acceleration changes through the out-of-plane motion of a mass in the Z direction. In order to improve the detection sensitivity of the sensor within the range of the sensor in a limited chip size, the stiffness of the spring beam is usually reduced. However, the reduction of the stiffness of the spring beam makes the sensor more likely to be damaged when it encounters an over-range acceleration impact, thereby affecting the reliability and service life of the sensor.

[0003] In order to solve the above problems, a stop structure is introduced in the acceleration sensor in the prior art, such as a hard stop structure arranged in-plane or out-of-plane, which is used to limit the excessive displacement of the mass and prevent the spring beam from being broken due to excessive bending. However, in application, when the sensitive structure is subjected to an inertial force and collides with the limit block, stress concentration will occur in the spring beam and the block area, which will cause structural damage, adhesion and other failure problems, seriously affecting the performance and stability of the sensor.

[0004] In addition, the traditional stop structure often uses a separate processing technology from the sensitive structure, which increases the process complexity and manufacturing cost. Therefore, there is an urgent need for a solution that can effectively improve the overload capacity without increasing the complexity of the process flow. SUMMARY

[0005] The purpose of the present application is to provide a method for manufacturing an acceleration sensor, which can form a protection structure and a stop structure at the same time as the electrode is prepared, not only improving the processing efficiency and shortening the preparation period, but also effectively reducing the manufacturing cost.

[0006] Another purpose of the present application is to provide an acceleration sensor that can avoid stress concentration when colliding and effectively improve the reliability and service life of the device.

[0007] The present application is implemented as follows:

[0008] In one aspect, the present application provides a method for manufacturing an acceleration sensor, comprising:

[0009] depositing a first sacrificial layer and a first structure layer as a fixed electrode on the surface of the substrate in sequence;

[0010] patterning and etching the first structure layer to form a protection structure in a predetermined area;

[0011] depositing a second sacrificial layer on the surface of the first structure layer;

[0012] etching the surface of the second sacrificial layer to form a groove with a depth less than the thickness of the second sacrificial layer; the groove is projected within the outer contour of the projection of the protection structure;

[0013] forming a second structure layer as a mass electrode on the surface of the second sacrificial layer; the second structure layer is correspondingly formed as a protrusion at the groove;

[0014] patterning and etching the second structure layer to form a stop structure; the stop structure at least partially overlaps with the projection of the protection structure on the substrate;

[0015] releasing the first sacrificial layer and the second sacrificial layer; wherein the second sacrificial layer between the mass electrode and the fixed electrode is released to form a moving space; a part of the second sacrificial layer is reserved to support the second structure layer; the first sacrificial layer between the protection structure and the substrate is released to form an avoiding space; a part of the first sacrificial layer is reserved to support the fixed electrode and the protection structure on the substrate.

[0016] As an optional implementation, the patterning and etching the first structure layer to form the protection structure comprises:

[0017] simultaneously forming a first release hole on the protection structure through patterning and etching.

[0018] As an optional implementation, the patterning and etching the second structure layer to form the stop structure comprises:

[0019] simultaneously forming a second release hole on the mass electrode and the stop structure through patterning and etching.

[0020] As an optional implementation, the patterning and etching the second structure layer to form the stop structure comprises:

[0021] simultaneously forming a support column and a spring beam connecting the support column and the mass electrode on the second structure layer through patterning and etching; the support column is connected with the substrate through the second sacrificial layer; or, the support column is connected with the substrate through the second sacrificial layer and the first sacrificial layer.

[0022] As an optional implementation, the stop structure comprises a first floating island and a plurality of cantilever beams arranged circumferentially around the first floating island; one end of the cantilever beam is connected with the first floating island, and the other end extends away from the first floating island to connect with the mass electrode; the protrusion is arranged on the side of the first floating island close to the protection structure.

[0023] As an optional implementation, the protection structure comprises a second floating island, an outer frame circumferentially surrounding the second floating island, and a plurality of spring folded beams circumferentially arranged around the second floating island; the outer frame is connected with the substrate and has a preset interval with the fixed electrode; one end of the spring folded beam is connected with the second floating island and the other end is connected with the outer frame; the second floating island is provided with an abutting portion close to one side of the first floating island, and the projection of the protrusion and the abutting portion are coincident on the substrate.

[0024] In another aspect, the application provides an acceleration sensor, comprising a substrate, and a first structure layer and a second structure layer sequentially arranged on the substrate; the first structure layer comprises a fixed electrode and a protection structure; the second structure layer comprises a mass electrode and a stop structure; the mass electrode has a preset interval with the fixed electrode and the projection of the mass electrode and the fixed electrode at least partially overlap on the substrate; the projection of the stop structure and the protection structure at least partially overlap on the substrate; the stop structure is provided with a protrusion close to one side of the protection structure; the protection structure has a clearance space with the substrate; when the mass electrode moves to one side of the substrate under the action of acceleration, the protrusion and the protection structure abut, so that the protection structure elastically deforms.

[0025] As an optional implementation, the second structure layer is further provided with a spring beam and a support column fixedly arranged on the substrate; one end of the spring beam is connected with the support column and the other end extends away from the support column and is connected with the mass electrode; when the mass electrode moves in a direction perpendicular to the substrate under the action of acceleration, the spring beam elastically deforms.

[0026] As an optional implementation, an elastic buffer structure is arranged between the support column and the mass electrode; the elastic force generated by the deformation of the elastic buffer structure is perpendicular to the elastic force generated by the deformation of the protection structure.

[0027] As an optional implementation, the spring beam is arranged on opposite two sides of the support column; the elastic buffer structure is arranged on the other opposite two sides of the support column.

[0028] As an optional implementation, the mass electrode comprises a first negative electrode and a first positive electrode arranged on two sides of the extension direction of the spring beam respectively; the fixed electrode comprises a second negative electrode corresponding to the position of the first negative electrode and a second positive electrode corresponding to the position of the first positive electrode.

[0029] As an optional implementation, there are two groups of protection structures symmetrically arranged with respect to the extension direction of the spring beam; each group has at least two protection structures and is arranged in intervals along the extension direction of the spring beam.

[0030] The beneficial effects of the application include:

[0031] The preparation method provided in the application adopts an integrated patterned etching process to form multiple functional components, such as fixed electrodes and protective structures, mass block electrodes and stop structures, in one structure layer at one time. The design of the embodiment of the application reduces the process steps for separately providing structures such as stop structures in traditional processing, and reduces the complexity of device manufacturing. At the same time, the process of the application does not need to introduce special materials or equipment, further controlling the manufacturing cost, and being conducive to realizing large-scale production and popularization and application. The application significantly enhances the structural stability of the sensor in a high-impact and large-vibration environment through the synergistic effect of the protective structure and the stop structure. When the mass block has an over-limit displacement, the stop structure does not directly collide with the substrate or the fixed structure, but first contacts the protective structure, which absorbs part of the impact energy and relieves the stress concentration problem. This "soft stop" mechanism effectively prevents the occurrence of traditional failure modes such as spring beam fracture and structure adhesion, thereby improving the impact resistance and long-term use stability of the device.

[0032] The acceleration sensor provided in the embodiment of the application sets a protrusion on the side of the stop structure close to the protective structure, and makes the projection of the protrusion and the protective structure on the substrate at least partially coincide, to ensure that when the mass block electrode moves in the direction of the substrate under a large impact, the protrusion of the stop structure can accurately contact the protective structure, thereby limiting the excessive displacement of the mass block. The protective structure in the embodiment of the application is provided with a relief space between the substrate, so that it has elastic deformation capability and deforms elastically when the protrusion exerts pressure, thereby absorbing impact energy. At the same time, the stop structure also has elastic deformation capability, so that the stop structure and the protective structure of the embodiment of the application constitute a double elastic buffer system, effectively avoiding the stress concentration and structural damage caused by traditional hard stop, and improving the impact resistance and structural reliability of the sensor in a high-impact environment, while the stability and service life of the device are enhanced through the elastic buffer mechanism. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0034] Figure 1 FIG. 1 is a structural schematic diagram of an acceleration sensor according to an embodiment of the application;

[0035] Figure 2 FIG. 2 is a structural schematic diagram of an acceleration sensor according to another embodiment of the application;

[0036] Figure 3Fig. 3 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0037] Figure 4 Fig. 4 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0038] Figure 5 Fig. 5 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0039] Figure 6 Fig. 6 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0040] Figure 7 Fig. 7 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0041] Figure 8 Fig. 8 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0042] Figure 9 Fig. 9 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0043] Figure 10 Fig. 10 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0044] Figure 11 Fig. 11 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0045] Figure 12 Fig. 12 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0046] Figure 13 Fig. 13 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0047] Figure 14 Fig. 14 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0048] Figure 15 Fig. 15 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0049] Figure 16 Fig. 16 is a schematic view of an acceleration sensor according to an embodiment of the present application;

[0050] Figure 17 Fig. 17 is a schematic view of an acceleration sensor according to an embodiment of the present application.

[0051] Fig. 18 is a schematic view of an acceleration sensor according to an embodiment of the present application.

[0052] 100-substrate; 101-first sacrificial layer; 102-fixed electrode; 103-first structural layer; 104-protection structure; 105-second sacrificial layer; 106-recess; 107-mass electrode; 108-second structural layer; 109-bump; 110-stop structure; 111-moving space; 112-avoidance space; 113-first release hole; 114-second release hole; 115-supporting column; 116-spring beam; 117-first floating island; 118-cantilever beam; 119-second floating island; 120-spring folded beam; 121-elastic buffer structure. DETAILED DESCRIPTION

[0053] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0054] Therefore, the detailed description of the embodiments of the present application provided below in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0055] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", "third" and the like are only used to distinguish description, and cannot be understood as indicating or implying relative importance.

[0056] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "setting", "mounting", "connecting", "connecting" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0057] In the field of micro-electro-mechanical system (MEMS) technology, Z-axis high-g acceleration sensors are widely used in occasions that need to withstand large impact and high vibration environment, and the core function thereof is to perceive acceleration changes through the off-plane motion of a mass in the Z direction. In order to improve the detection sensitivity of the sensor in the range of the range in the limited chip size, the spring beam stiffness is usually reduced. However, the reduction of the spring beam stiffness will make the sensor more prone to structural damage when encountering an over-range acceleration impact, thereby affecting the reliability and service life thereof.

[0058] In order to solve the above problems, a stop structure is introduced in the acceleration sensor in the prior art, such as a hard stop structure arranged in-plane or out-of-plane, for limiting the excessive displacement of the mass and preventing the spring beam from being broken due to excessive bending. However, in application, when the sensitive structure is subjected to an inertial force and collides with the limit block, stress concentration will occur in the spring beam and the block area, thereby causing structural damage, adhesion and other failure problems, which seriously affect the performance and stability of the sensor.

[0059] In addition, the traditional stop structure often uses a processing technology independent of the sensitive structure, which increases the process complexity and manufacturing cost.

[0060] To solve the above technical problems, the embodiments of the present application provide an acceleration sensor preparation method and an acceleration sensor.

[0061] The speed sensor preparation method provided by the embodiments of the present application comprises:

[0062] Referring to FIG. 1, Figure 1 a first sacrificial layer 101 and a first structure layer 103 serving as a fixed electrode 102 are sequentially deposited on the surface of a substrate 100;

[0063] Referring to FIG. 2, Figure 2 the first structure layer 103 is patterned and etched to form a protection structure 104 in a predetermined area;

[0064] Referring to FIG. 3, Figure 3 a second sacrificial layer 105 is deposited on the surface of the first structure layer 103;

[0065] The surface of the second sacrificial layer 105 is etched to form a groove 106 with a depth less than the thickness of the second sacrificial layer 105; the projection of the groove 106 falls within the outer contour of the projection of the protection structure 104;

[0066] Referring to FIG. 4, Figure 4 a second structure layer 108 serving as a mass electrode 107 is deposited on the surface of the second sacrificial layer 105; the second structure layer 108 corresponds to form a protrusion 109 at the groove 106;

[0067] Referring to FIG. 5, Figure 5As shown, the second structural layer 108 is patterned and etched to form the stop structure 110; the projection of the stop structure 110 and the protection structure 104 on the substrate 100 at least partially overlaps;

[0068] Referring to Figure 6 As shown, the first and second sacrificial layers 101 and 105 are released; specifically, the second sacrificial layer 105 between the mass electrode 107 and the fixed electrode 102 is released to form the movement space 111; part of the second sacrificial layer 105 is reserved to support the second structural layer 108; the first sacrificial layer 101 between the protection structure 104 and the substrate 100 is released to form the avoidance space 112; part of the first sacrificial layer 101 is reserved to support the fixed electrode 102 and the protection structure 104 on the substrate 100.

[0069] It should be noted that the embodiments of the present application adopt a design method combining two structural layers and two sacrificial layers. Specifically, the first sacrificial layer 101 and the first structural layer 103 are deposited on the substrate 100 in sequence, and then the second sacrificial layer 105 and the second structural layer 108 are deposited thereon. By defining structures in different layers and then selectively releasing the sacrificial layers, the integration of multiple functional structures in the vertical direction is achieved. The multi-layer architecture of the embodiments of the present application not only helps to build a complex three-dimensional movement space 111, but also can flexibly control the relative height and spacing between structures, thereby providing accurate mechanical response characteristics and effective displacement limiting mechanism for the sensor.

[0070] In order to simplify the manufacturing process and improve device consistency, the present application proposes an integrated patterned etching method. In the processing of the first structural layer 103, the fixed electrode 102 and the protection structure 104 are formed at the same time by one patterned etching of the layer; similarly, in the processing of the second structural layer 108, the mass electrode 107 and the stop structure 110 are also formed at the same time by one etching step. The method of the embodiments of the present application for realizing multiple functional components in the same structural layer avoids the need for a separate processing step for the stop structure 110 in the traditional process, effectively reduces the number of process steps, reduces the manufacturing complexity and cost, and improves the integration and repeatability of the device.

[0071] It should be emphasized that the embodiments of the present application obtain the fixed electrode 102 and the protection structure 104 on the first structural layer 103 at the same time by one patterned etching. Similarly, the embodiments of the present application obtain the mass electrode 107 and the stop structure 110 on the second structural layer 108 at the same time by one patterned etching.

[0072] To solve the problem of stress concentration in the process of contact collision between the stop structure 110 and the protection structure 104, the embodiments of the present application introduce a groove 106 in the process for forming the protrusion 109. Specifically, a groove 106 with a depth less than the thickness of the second sacrificial layer 105 is etched on the surface of the second sacrificial layer 105, and then when the second structural layer 108 is deposited, the groove 106 area naturally forms a downward protrusion 109 structure. In the final device, the protrusion 109 is located directly above or in the projection range of the protection structure 104. When the mass electrode 107 moves, the protrusion 109 under the stop structure 110 abuts against the elastic protection structure 104, so that the stop structure 110 and the protection structure 104 are not in direct rigid contact, but through the buffer structure of the protection structure 104 to achieve the effect of "soft stop", thereby significantly reducing the damage risk caused by collision, and improving the stability and service life of the device in extreme impact environment.

[0073] In addition, since the mass electrode 107 and the fixed electrode 102 are at different potentials, if they are in direct contact, they are easy to cause device failure due to electrostatic attraction. By setting the protrusion 109, the protrusion 109 and the protection structure 104 are in the same potential state, a certain gap can be reserved between them, and the attraction phenomenon can be effectively prevented, thereby further improving the stability and reliability of the device.

[0074] Among them, the first structural layer 103 and the second structural layer 108 can be polycrystalline silicon; the first sacrificial layer 101 and the second sacrificial layer 105 can be silicon oxide; and the substrate 100 can be a silicon substrate 100. Among them, the silicon oxide of the first sacrificial layer 101 and the second sacrificial layer 105 can be etched by using hydrofluoric acid solution or gaseous hydrofluoric acid to realize the release of part of the area.

[0075] It should be noted that the partial selective release of the first sacrificial layer 101 and the second sacrificial layer 105 can be performed in one process. Those skilled in the art can achieve precise release by the following conditions.

[0076] Firstly, by designing the position and size of the release hole, the path of hydrofluoric acid entering the sacrificial layer can be accurately controlled. The release hole is usually formed after the structural layer is patterned and is located above or near the area to be released. By reasonably arranging the position of the release hole, it can be ensured that the hydrofluoric acid can effectively contact the silicon oxide area to be released, while avoiding affecting the area that does not need to be released.

[0077] Secondly, by controlling the treatment time and concentration of hydrofluoric acid, precise release can be achieved. In the case of small thickness difference between the first sacrificial layer 101 and the second sacrificial layer 105, no graded release is needed, and the release process can be completed in one time. When the thickness difference between the first sacrificial layer 101 and the second sacrificial layer 105 is large, and the exposed area of the silicon oxide in different layers is different, by adjusting the etching time and concentration of HF, the etching depth and range can be controlled, so that the graded release of different areas can be realized. For example, the second sacrificial layer 105 is released first to form the suspended state of the mass electrode 107 and the stop structure 110, and then the first sacrificial layer 101 is further released to release the space below the protection structure 104 and the fixed electrode 102.

[0078] In summary, by the design of the release hole, the control of the hydrofluoric acid treatment parameters, and the coordinated release strategy of the multi-layer sacrificial layer, the precise release of the first sacrificial layer 101 and the second sacrificial layer 105 is effectively realized, so as to ensure the correct three-dimensional configuration and movement freedom of each functional structure in the sensor, and provide a solid guarantee for the realization of device performance and reliability.

[0079] It should be noted that the specific thickness of the polysilicon layer and the silicon oxide layer is not specially limited here, and those skilled in the art can set it according to needs. For example, the thickness of the first sacrificial layer 101 is 2 μm; the thickness of the second sacrificial layer 105 is 0.5-3 μm; the thickness of the first structure layer 103 is 0.5-3 μm; and the thickness of the second structure layer 108 is 10-40 μm. The specific thickness of each layer can be controlled by CMP process for planarization.

[0080] It should be noted that the spacing between the protrusion 109 and the protection structure 104 can be designed by those skilled in the art according to specific conditions. For example, when the mass electrode 107 is not moving, the spacing between the protrusion 109 and the protection structure 104 is 0.4-1.5 μm.

[0081] The technical effects that can be achieved by the embodiments of the present application are as follows:

[0082] An integrated patterning etching process is adopted to form multiple functional components in one structure layer at a time, such as the fixed electrode 102 and the protection structure 104, the mass electrode 107 and the stop structure 110. The design of the embodiments of the present application reduces the process steps for separately setting the stop structure 110 and other structures in the traditional processing, and reduces the complexity of device manufacturing. At the same time, the process of the embodiments of the present application does not need to introduce special materials or equipment, further controlling the manufacturing cost, which is conducive to the realization of large-scale production and popularization and application.

[0083] The application significantly enhances the structural stability of the sensor in a high-impact, large-vibration environment through the synergistic effect of the protection structure 104 and the stop structure 110. When the mass block undergoes an over-limit displacement, the stop structure 110 does not directly collide with the substrate 100 or the fixed structure, but first contacts the protection structure 104, which absorbs part of the impact energy and relieves the stress concentration problem. This "soft stop" mechanism effectively prevents the occurrence of traditional failure modes such as spring beam 116 fracture and structural adhesion, thereby improving the impact resistance and long-term stability of the device.

[0084] As an optional embodiment, the first structure layer 103 is patterned and etched to form the protection structure 104, including:

[0085] Referring to Figure 6 , Figure 7 , a first release hole 113 is simultaneously formed on the protection structure 104 by patterned etching.

[0086] Preferably, referring to Figure 7 , the first release hole 113 has multiple and is uniformly spaced on the protection structure 104. The setting of the first release hole 113 enables the part of the first sacrificial layer 101 covered by the protection structure 104 to be fully released.

[0087] In the embodiment of the application, the first structure layer 103 is patterned and etched to form the fixed electrode 102 and the protection structure 104, and at the same time, multiple first release holes 113 are etched on the protection structure 104. These release holes are preferably uniformly spaced on the surface of the protection structure 104, and their role is to provide a corrosion channel for subsequent corrosion of the first sacrificial layer 101 using hydrofluoric acid. Through this design, the first sacrificial layer 101 covered below the protection structure 104 can be fully contacted and corroded and removed, thereby realizing the complete release of this area and forming the required avoidance space 112.

[0088] The technical effects that can be achieved by the embodiment of the application are as follows: on the one hand, multiple uniformly distributed release holes can improve the corrosion efficiency and ensure that the area of the first sacrificial layer 101 below the protection structure 104 is fully removed, avoiding residual structures that cannot be suspended or limited in movement; on the other hand, the reasonable layout of the first release hole 113 can also reduce the corrosion blind area and improve the consistency of the process and the yield of the device. In addition, since the first release hole 113 is completed at the same time as the formation of the protection structure 104, no additional processing steps are required, thus helping to simplify the manufacturing process, reduce costs, and at the same time ensure the mechanical integrity and functional reliability of the overall structure.

[0089] As an optional embodiment, the second structure layer 108 is patterned and etched to form the stop structure 110, including:

[0090] Referring to Figure 8 、 Figure 9 As shown in FIG. 11, the second release hole 114 is formed on the mass electrode 107 and the stop structure 110 simultaneously by patterning etching.

[0091] It should be noted that the second release hole 114 is etched on the mass electrode 107 and the stop structure 110 simultaneously while the second structure layer 108 is patterned and etched to form the mass electrode 107 and the stop structure 110. The second release hole 114 can be distributed in multiple on the second structure layer 108, and the purpose is to provide an effective etching channel for subsequent etching of the second sacrificial layer 105 by hydrofluoric acid. Through this design, the second sacrificial layer 105 located below the mass electrode 107 and the stop structure 110 can be fully contacted and removed, thereby forming the required movement space 111 in the corresponding area, ensuring the free displacement of the mass and the function realization of the stop structure 110.

[0092] The technical effects that can be produced by the embodiments of the present application are as follows: first, the plurality of second release holes 114 provided on the mass electrode 107 and the stop structure 110 can significantly improve the uniformity and efficiency of the sacrificial layer etching, ensure the formation of a complete and consistent overhanging area below the mass, and avoid the limitation of movement or device failure caused by the residual sacrificial layer; second, the reasonable layout of the release hole helps to reduce the etching blind area, improve the consistency and reliability of the device. In addition, since the release hole is completed simultaneously in the process of forming the mass electrode 107 and the stop structure 110, no additional process steps are required, which further simplifies the manufacturing process, reduces the process complexity, and is also conducive to improving the product yield and mass production feasibility.

[0093] It should be noted that the shape and size of the first release hole 113 and the second release hole 114 are not specially limited here, and those skilled in the art can set them according to needs.

[0094] Further, the second structure layer 108 is patterned and etched to form the stop structure 110, including:

[0095] Referring to Figure 10 As shown in FIG. 11, the second release hole 114 is formed on the mass electrode 107 and the stop structure 110 simultaneously by patterning etching.

[0096] The support column 115 is connected with the substrate 100 through the second sacrificial layer 105; or, the support column 115 is connected with the substrate 100 through the second sacrificial layer 105 and the first sacrificial layer 101.

[0097] In this embodiment, during the patterning etching of the second structural layer 108, not only are the mass block electrode 107 and the stop structure 110 formed, but the support pillar 115 and the spring beam 116 for connecting the support pillar 115 and the mass block electrode 107 are also simultaneously processed. Through this process, multiple key functional components are formed on the same structural layer at once.

[0098] It should be noted that no release holes are provided on the support pillar 115 and the portion near its edge to prevent hydrofluoric acid from corroding the sacrificial layer beneath it. This ensures that the support pillar 115 is connected to the substrate 100 via the underlying sacrificial layer, thereby forming a reliable support structure after the release process. This integrated etching method eliminates the need for separate processing steps for each structure, significantly simplifying the manufacturing process of MEMS devices and improving structural consistency and alignment accuracy.

[0099] The technical effects that can be achieved by the embodiments of this application are as follows: First, by forming the mass block electrode 107, the stop structure 110, the support column 115 and the spring beam 116 simultaneously through a single patterned etching process, the manufacturing process is not only effectively simplified, but also the process complexity and production cost are reduced, thereby improving the mass production capability of the device. Second, the formation of each functional structure in the same step helps to improve the structural consistency of the device, thereby improving the performance stability of the sensor.

[0100] Reference Figure 8 As shown, in one optional implementation, the stop structure 110 includes a first floating island 117 and a plurality of cantilever beams 118 arranged circumferentially around the first floating island 117; one end of the cantilever beam 118 is connected to the first floating island 117, and the other end extends away from the first floating island 117 to connect to the mass block electrode 107; a protrusion 109 is provided on the side of the first floating island 117 near the protective structure 104.

[0101] It should be noted that the cantilever beam 118 provides the first suspended island 117 with a certain degree of elasticity. When the mass electrode 107 is subjected to a large impact (such as a 100g acceleration), the protrusion 109 on the stop structure 110 contacts the lower protective structure 104. The contact force is transmitted to the cantilever beam 118 through the first suspended island 117, causing the cantilever beam 118 to deform and generate an elastic force that pulls the protrusion 109 back. This reduces the kinetic energy of the first suspended island 117 moving towards the protective structure 104. The greater the displacement of the protrusion 109 towards the protective structure 104, the greater the elastic force generated by the cantilever beam 118, achieving dynamic buffering. In this embodiment, the cantilever beam 118 provides the stop structure 110 with elasticity, which, together with the protective structure 104, achieves dual elastic buffering, effectively reducing the damage to the acceleration sensor structure caused by large impacts.

[0102] It should be noted that the number of cantilever beams 118 is not particularly limited here. Exemplarily, there are four cantilever beams 118, and the first floating island 117 is a rectangular structure. The four cantilever beams 118 are respectively arranged at the four side walls of the first floating island 117. Exemplarily, there are eight cantilever beams 118, two cantilever beams 118 extending in perpendicular directions are respectively arranged at each corner of the first floating island 117, or two cantilever beams 118 parallel to each other are arranged at the middle part of each side.

[0103] It should be noted that: first, the cantilever beams 118 give the stop structure 110 certain elastic ability, so that it can absorb energy by deformation when impacted, avoiding structural damage that may be caused by rigid collision; second, in combination with the use of the protection structure 104, a double-elastic buffer system is formed, further enhancing the protection of the internal components of the sensor, reducing stress concentration, and improving the overall reliability and service life of the device. In addition, this design of the embodiment of the application helps to optimize the response behavior of the sensor under extreme conditions, ensuring good performance and stability even in a high-impact environment. In this way, the embodiment of the application can effectively improve the impact resistance and long-term reliability of the acceleration sensor.

[0104] Referring to Figure 7 As an optional implementation, the protection structure 104 includes a second floating island 119, an outer frame circumferentially surrounding the second floating island 119, and a plurality of spring folded beams 120 arranged circumferentially around the second floating island 119; one end of the spring folded beam 120 is connected to the second floating island 119, and the other end is connected to the outer frame; the second floating island 119 is provided with an abutting portion near the side of the first floating island 117, and the projection 109 and the abutting portion are projected and overlapped on the substrate 100.

[0105] The outer frame is connected to the substrate 100 and has a predetermined distance from the fixed electrode 102; it should be noted that the outer frame is fixedly connected to the substrate 100 and is used to support the second floating island 119. The outer frame has a distance from the fixed electrode 102, so that the protection structure 104, the stop structure 110, and the mass electrode 107 have the same potential. Since the fixed electrode 102 is not connected to the outer frame, the isolation and disconnection ensure that the potential of the protection structure 104 and the fixed electrode 102 is not equal, that is, the potential of the mass electrode 107 and the fixed electrode 102 is not equal, to ensure accurate detection.

[0106] It should be noted that the protective structure 104 includes a second suspended island 119 and multiple spring-loaded folding beams 120 arranged circumferentially around it. These spring-loaded folding beams 120 are composed of multiple sequentially connected S-shaped or bow-shaped structures, one end of which is connected to the second suspended island 119, and the other end extends and is connected to the fixed electrode 102. An abutment portion is provided on the side of the second suspended island 119 near the first suspended island 117 in the stop structure 110. This abutment portion coincides with the projection position of the protrusion 109 on the stop structure 110 onto the substrate 100, ensuring accurate contact between the two during extreme displacement. This structural design not only gives the flexible protective structure 104 good elastic deformation capability, but also achieves a larger deformation absorption space and a more uniform stress distribution through the spring-loaded folding beams 120.

[0107] The spring-folding beam 120 in this embodiment employs a design of multiple S-shaped or bow-shaped structures connected in series, significantly improving the elastic range and buffering capacity of the flexible protection structure 104. This allows it to effectively absorb energy when subjected to impact, reducing damage to the core components of the sensor. In this embodiment, the abutment portion on the second suspended island 119 is precisely aligned with the protrusion 109 in the stop structure 110, achieving accurate and reliable contact control and avoiding stress concentration or functional failure due to misalignment. The flexible protection structure 104 works in conjunction with the stop structure 110 of the first suspended island 117 with cantilever beam 118 to jointly construct a dual elastic buffering mechanism, further enhancing the stability and reliability of the sensor under high-impact environments, thereby significantly improving the overall performance and service life of the device.

[0108] Figure 12 , Figure 13 The simulation results for the accelerometer without the protective structure 104 and the stop structure 110 show that when there is no protective structure 104, the mass block is displaced by inertial force, and the collision stress between the rigid limiting bump and the substrate stop is 351 MPa. The stress is relatively large and close to the allowable stress of silicon material, which poses a risk of breakage.

[0109] Figure 14 , Figure 15 Simulation results for the embodiment of this application after adding the protective structure 104. The stress on the protrusion 109 below the stop structure 110 is reduced to 120MPa, which is a 65% reduction in collision stress compared to the prior art without a protective structure; at the same time, the stress on the spring folding beam 120 is 130MPa, which is far below the allowable stress of silicon material, thus improving structural safety.

[0110] Figure 16 , Figure 17 Simulation results for an embodiment of this application where both the protective structure 104 and the stop structure 110 are simultaneously provided. (Refer to...) Figure 17As shown, when the protection structure 104 and the stop structure 110 are added, the eight cantilever beams disperse most of the stress of the bump 109 collision, so that the stress of the bump 109 collision itself is only 25 MPa, compared with Figure 15 Further reduced by 80%, greatly reducing the collision stress of the bump 109, with strong environmental reliability, so that the Z-axis acceleration sensor can adapt to most large dynamic range or extreme environment without failure.

[0111] Referring to Figure 6 , Figure 10 As shown, the acceleration sensor provided by the application comprises a substrate 100, and a first structure layer 103 and a second structure layer 108 sequentially arranged on the substrate 100; the first structure layer 103 comprises a fixed electrode 102 and a protection structure 104; the second structure layer 108 comprises a mass electrode 107 and a stop structure 110; the mass electrode 107 and the fixed electrode 102 are pre-set at a distance and at least partially overlap in projection on the substrate 100; the stop structure 110 and the protection structure 104 at least partially overlap in projection on the substrate 100; the stop structure 110 is provided with a bump 109 close to one side of the protection structure 104; the protection structure 104 and the substrate 100 have a clearance space 112; when the mass electrode 107 is stressed to move close to one side of the substrate 100, the bump 109 and the protection structure 104 abut, so that the protection structure 104 elastically deforms.

[0112] Among them, the fixed electrode 102 and the protection structure 104 are at the same level; the mass electrode 107 and the stop structure 110 are also at the same level, and the structures at the same level can be obtained in one-time patterning etching.

[0113] The acceleration sensor provided by the embodiment of the application sets the bump 109 close to one side of the protection structure 104 of the stop structure 110, and makes the projection of the bump 109 and the protection structure 104 on the substrate 100 at least partially coincide, so as to ensure that when the mass electrode 107 is subjected to a large impact and moves in the direction of the substrate 100, the bump 109 of the stop structure 110 can accurately contact the protection structure 104, thereby limiting the excessive displacement of the mass. At the same time, the clearance space 112 is provided between the protection structure 104 and the substrate 100, so that it has the ability of elastic deformation, and elastically deforms when the bump 109 applies pressure, thereby absorbing impact energy. This design effectively avoids the stress concentration and structural damage caused by the traditional hard stop, improves the impact resistance and structural reliability of the sensor in a high-impact environment, and at the same time enhances the stability and service life of the device through the elastic buffering mechanism.

[0114] The second structure layer 108 is further provided with a spring beam 116 and a support column 115 fixed on the substrate 100; one end of the spring beam 116 is connected to the support column 115, and the other end of the spring beam 116 extends away from the support column 115 and is connected to the mass electrode 107; when the mass electrode 107 is forced to move in the direction perpendicular to the substrate 100, the spring beam 116 is elastically deformed.

[0115] Referring to Figure 11 As an optional embodiment, the support column 115 and the mass electrode 107 are provided with an elastic buffer structure 121; the elastic force generated by the elastic buffer structure 121 is perpendicular to the elastic force generated by the protection structure 104.

[0116] It should be noted that the elastic buffer structure 121 is additionally arranged between the support column 115 and the mass electrode 107, and the elastic buffer structure 121 is designed to generate an elastic force in a direction perpendicular to the elastic force generated by the protection structure 104. This means that in addition to the original protection mechanism in the Z-axis direction (i.e., the direction perpendicular to the substrate 100), an additional elastic protection mechanism in the direction parallel to the substrate 100 is added. When the mass electrode 107 moves laterally due to impact and approaches the fixed electrode 102, the elastic buffer structure 121 can effectively absorb the unexpected lateral movement energy, preventing direct lateral collision between the mass electrode 107 and other components.

[0117] The embodiments of the present application ensure that not only can excessive impact force be effectively buffered in the vertical direction, but also potential collision risks caused by lateral displacement can be avoided in the horizontal direction, further enhancing the overall stability and reliability of the sensor; secondly, by arranging the elastic buffer structure 121 in different directions with independent action directions, more comprehensive mechanical protection can be provided without interfering with the original function.

[0118] Referring to Figure 9 As an optional embodiment, the spring beam 116 is arranged on the two opposite sides of the support column 115; and the elastic buffer structure 121 is arranged on the other two opposite sides of the support column 115.

[0119] The spatial layout of the embodiments of the present application enables the spring beam 116 and the elastic buffer structure 121 to bear mechanical functions in different directions, respectively. The spring beam 116 is mainly responsible for buffering in the vertical direction, and the elastic buffer structure 121 is used to absorb and relieve the impact or displacement of the mass in the direction parallel to the substrate 100.

[0120] The embodiments of the present application realize the integrated design of the multi-directional elastic response mechanism by arranging the spring beam 116 and the elastic buffer structure 121 on different sides of the support column 115, which not only improves the adaptability of the acceleration sensor in a complex vibration or impact environment, but also effectively avoids the risk of unintended collision of the mass block electrode 107 caused by lateral displacement. In addition, this symmetrical and functionally separated structural layout helps to improve the mechanical balance and structural stability of the device, thereby enhancing the measurement accuracy, anti-interference ability and long-term reliability of the sensor.

[0121] As an optional implementation, the mass block electrode 107 includes a first negative electrode and a first positive electrode arranged on both sides of the extension direction of the spring beam 116; and the fixed electrode 102 includes a second negative electrode corresponding to the position of the first negative electrode and a second positive electrode corresponding to the position of the first positive electrode.

[0122] Among them, there are two groups of protection structures 104 symmetrically arranged with respect to the extension direction of the spring beam 116; each group has at least two protection structures 104 and is arranged in intervals along the extension direction of the spring beam 116.

[0123] It should be noted that the mass block electrode 107 includes a first negative electrode and a first positive electrode arranged on both sides of the extension direction of the spring beam 116, and the fixed electrode 102 includes a second negative electrode and a second positive electrode corresponding thereto, wherein the second negative electrode corresponds to the position of the first negative electrode on the substrate 100, and the second positive electrode corresponds to the position of the first positive electrode. This symmetrical electrode layout forms a variable capacitance structure between the mass block electrode 107 and the fixed electrode 102 in the Z-axis direction (perpendicular to the substrate 100 direction), which can more accurately sense the displacement change of the mass block electrode 107, i.e. the mass block under the action of acceleration, and at the same time, through the pairing design of the positive and negative electrodes, it helps to improve the signal output stability and detection sensitivity of the sensor.

[0124] It should be noted that: first, the symmetrical layout of the positive and negative electrodes distributed on both sides of the spring beam 116 can realize a differential capacitance detection mechanism, effectively improving the recognition ability of the sensor to small acceleration changes and enhancing the anti-interference performance; second, the positive and negative electrodes form independent capacitance pairs with the corresponding fixed electrode 102, which is conducive to improving the linearity and accuracy of signal acquisition, thereby optimizing the overall performance of the sensor; in addition, the combination of this electrode structure and the aforementioned multi-directional elastic buffer mechanism not only ensures the structural safety of the device in a high-impact environment, but also realizes high sensitivity and high stability detection of acceleration changes, providing strong support for the realization of high-performance MEMS acceleration sensors.

[0125] The above descriptions are only the preferred embodiments of the present application, and are not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of manufacturing an acceleration sensor, characterized by, The application relates to a method for manufacturing a micro-mechanical resonator, comprising the following steps: Depositing a first sacrificial layer (101) and a first structure layer (103) serving as a fixed electrode (102) on the surface of a substrate (100) in sequence; Performing patterned etching on the first structure layer (103) to form a protection structure (104) in a preset area; Depositing a second sacrificial layer (105) on the surface of the first structure layer (103); Performing etching on the surface of the second sacrificial layer (105) to form a groove (106) with a depth smaller than the thickness of the second sacrificial layer (105); the projection of the groove (106) falls within the projection of the protection structure (104); Forming a second structure layer (108) serving as a mass electrode (107) on the surface of the second sacrificial layer (105); the second structure layer (108) corresponds to form a protrusion (109) at the groove (106); Performing patterned etching on the second structure layer (108) to form a stop structure (110); the projection of the stop structure (110) and the protection structure (104) on the substrate (100) at least partially overlaps; Releasing the first sacrificial layer (101) and the second sacrificial layer (105); wherein the second sacrificial layer (105) between the mass electrode (107) and the fixed electrode (102) is released to form a movement space (111); part of the second sacrificial layer (105) is reserved to support the second structure layer (108); the first sacrificial layer (101) between the protection structure (104) and the substrate (100) is released to form an avoidance space (112); part of the first sacrificial layer (101) is reserved to support the fixed electrode (102) and the protection structure (104) on the substrate (100).

2. The acceleration sensor manufacturing method according to claim 1, wherein The method further comprises the following steps: Simultaneously forming a first release hole (113) on the protection structure (104) through patterned etching.

3. The acceleration sensor manufacturing method according to claim 1, wherein The method further comprises the following steps: Simultaneously forming a second release hole (114) on the mass electrode (107) and the stop structure (110) through patterned etching.

4. The acceleration sensor manufacturing method according to claim 1, wherein The method further comprises the following steps: Simultaneously forming a support column (115) and a spring beam (116) connecting the support column (115) and the mass electrode (107) on the second structure layer (108) through patterned etching; the support column (115) is connected with the substrate (100) through the second sacrificial layer (105); or the support column (115) is connected with the substrate (100) through the second sacrificial layer (105) and the first sacrificial layer (101).

5. The method of claim 1-4, wherein The stop structure (110) comprises a first floating island (117) and a plurality of cantilever beams (118) arranged circumferentially around the first floating island (117); one end of the cantilever beam (118) is connected to the first floating island (117), and the other end extends away from the first floating island (117) to connect the mass electrode (107); the protrusion (109) is arranged on the side of the first floating island (117) close to the protection structure (104).

6. The acceleration sensor manufacturing method according to claim 5, wherein The protection structure (104) comprises a second floating island (119), an outer frame circumferentially surrounding the second floating island (119), and a plurality of spring folded beams (120) arranged circumferentially around the second floating island (119); the outer frame is connected to the substrate (100) and has a predetermined distance from the fixed electrode (102); one end of the spring folded beam (120) is connected to the second floating island (119), and the other end is connected to the outer frame; the second floating island (119) is provided with an abutting portion on the side close to the first floating island (117), and the protrusion (109) and the abutting portion are projected on the substrate (100) and coincide.

7. An acceleration sensor, characterized by The second structure layer (108) is further provided with a spring beam (116) and a support column (115) fixedly arranged on the substrate (100); one end of the spring beam (116) is connected to the support column (115), and the other end extends away from the support column (115) and is connected to the mass electrode (107); when the mass electrode (107) moves in the direction perpendicular to the substrate (100) under the action of acceleration, the spring beam (116) elastically deforms.

8. The acceleration sensor according to claim 7, characterized in that The second structure layer (108) is further provided with a spring beam (116) and a support column (115) fixedly arranged on the substrate (100); one end of the spring beam (116) is connected to the support column (115), and the other end extends away from the support column (115) and is connected to the mass electrode (107); when the mass electrode (107) moves in the direction perpendicular to the substrate (100) under the action of acceleration, the spring beam (116) elastically deforms.

9. The acceleration sensor according to claim 8, characterized in that The support column (115) and the mass electrode (107) are provided with an elastic buffer structure (121); the elastic force generated by the deformation of the elastic buffer structure (121) is perpendicular to the elastic force generated by the deformation of the protection structure (104).

10. Acceleration sensor according to any of claims 7 to 9, characterized in that The mass electrode (107) comprises a first negative electrode and a first positive electrode arranged respectively on both sides of the extension direction of the spring beam (116); the fixed electrode (102) comprises a second negative electrode corresponding to the position of the first negative electrode and a second positive electrode corresponding to the position of the first positive electrode.

11. The acceleration sensor according to claim 10, characterized in that There are two groups of the protection structure (104) arranged symmetrically along the extension direction of the spring beam (116); each group has at least two protection structures (104) and is arranged at intervals along the extension direction of the spring beam (116).

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