Acceleration sensor preparation method and acceleration sensor

Abstract

The invention relates to the technical field of micro electro mechanical systems, in particular to an acceleration sensor preparation method and an acceleration sensor, and the method comprises the steps: sequentially depositing a first sacrificial layer and a first structure layer as a fixed electrode on the surface of a substrate; performing patterning etching on the first structure layer to form a protection structure; depositing a second sacrificial layer on the surface of the first structure layer; etching the surface of the second sacrificial layer to form a groove of which the depth is 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 patterning etching on the second structure layer to form a backstop structure; the projections of the stop structure and the protection structure on the substrate are at least partially overlapped; and releasing the first sacrificial layer and the second sacrificial layer. According to the manufacturing method, the protection structure and the stop structure can be formed while the electrode is manufactured, the machining efficiency is improved, the manufacturing period is shortened, and the manufacturing cost is effectively reduced.

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 situations that need to withstand large impact and high vibration environments. 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 measurement range under the limited chip size, the spring beam stiffness is usually reduced. However, the reduction of the spring beam stiffness makes the sensor more likely to be structurally damaged when it encounters an over-range acceleration impact, thereby affecting its reliability and service life.

[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 which 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: In one aspect, the present application provides a method for manufacturing an acceleration sensor, comprising: depositing a first sacrificial layer and a first structure layer as a fixed electrode on the surface of the substrate in sequence; patterning and etching the first structure layer to form a protection structure in a predetermined area; depositing a second sacrificial layer on the surface of the first structure layer; etching the second-sacrificial-layer surface to form a groove with a depth less than the thickness of the second sacrificial layer; the groove is projected to fall within the outer contour of the projection of the protection structure; forming a second structure layer as the mass-electrode on the second-sacrificial-layer surface; the second structure layer is correspondingly formed as a protrusion at the groove; patterned etching the second structure layer to form a stop structure; the stop structure and the protection structure are at least partially overlapped in projection on the substrate; 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.

[0008] As an optional implementation, the patterned etching the first structure layer to form the protection structure comprises: simultaneously forming a first release hole on the protection structure by patterned etching.

[0009] As an optional implementation, the patterned etching the second structure layer to form the stop structure comprises: simultaneously forming a second release hole on the mass-electrode and the stop structure by patterned etching.

[0010] As an optional implementation, the patterned etching the second structure layer to form the stop structure comprises: simultaneously forming a support column and a spring beam connecting the support column and the mass-electrode on the second structure layer by patterned etching; the support column is connected to the substrate through the second-sacrificial layer; or, the support column is connected to the substrate through the second-sacrificial layer and the first-sacrificial layer.

[0011] 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 to the first floating island, and the other end extends away from the first floating island to connect the mass-electrode; the protrusion is arranged on the side of the first floating island close to the protection structure.

[0012] 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 folding beams arranged circumferentially around the second floating island; the outer frame is connected to the substrate and has a preset distance from the fixed-electrode; one end of the spring folding beam is connected to the second floating island, and the other end is connected to the outer frame; the second floating island is provided with an abutting portion on the side close to the first floating island, and the protrusion and the abutting portion are projected to overlap on the substrate.

[0013] In another aspect, the application provides an acceleration sensor, comprising a substrate, and a first structure layer and a second structure layer arranged on the substrate in sequence; 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 is preset a distance from the fixed electrode and the projection of the mass electrode on the substrate at least partially overlaps the projection of the fixed electrode on the substrate; the stop structure and the protection structure at least partially overlap in projection on the substrate; the stop structure is provided with a protrusion on the side close to the protection structure; the protection structure and the substrate have a clearance space; when the mass electrode moves to the side of the substrate under the action of acceleration, the protrusion and the protection structure abut, causing the protection structure to elastically deform.

[0014] As an optional embodiment, 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 to the support column, and the other end of the spring beam extends away from the support column and is connected to the mass electrode; when the mass electrode moves in the direction perpendicular to the substrate under the action of acceleration, the spring beam elastically deforms.

[0015] As an optional embodiment, 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.

[0016] As an optional embodiment, the spring beam is arranged on the opposite two sides of the support column; and the elastic buffer structure is arranged on the other opposite two sides of the support column.

[0017] As an optional embodiment, the mass electrode comprises a first negative electrode and a first positive electrode arranged on the two sides of the extension direction of the spring beam respectively; and 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.

[0018] As an optional embodiment, 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 the protection structures are arranged in intervals along the extension direction of the spring beam.

[0019] The beneficial effects of the application include: 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 controls the manufacturing cost, and is 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 structural adhesion, thereby improving the impact resistance and long-term stability of the device.

[0020] 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 protrusion at least partially coincide with the projection of the protective structure on the substrate, so as 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 applies 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

[0021] 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.

[0022] Figure 1 FIG. 1 is a structural schematic diagram of an acceleration sensor according to an embodiment of the application; Figure 2 FIG. 2 is a structural schematic diagram of an acceleration sensor according to another embodiment of the application; Figure 3 FIG. 3 is a structural schematic diagram of an acceleration sensor according to another embodiment of the application; Figure 4 Figure 4 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 5 Figure 5 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 6 Figure 6 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 7 Figure 7 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 8 Figure 8 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 9 Figure 9 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 10 Figure 10 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 11 Figure 11 is a structural schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 12 Figure 12 is a structural simulation schematic diagram of an acceleration sensor according to the prior art; Figure 13 Figure 13 is a structural simulation schematic diagram of an acceleration sensor according to the prior art; Figure 14 Figure 14 is a simulation schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 15 Figure 15 is a simulation schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 16 Figure 16 is a simulation schematic diagram of an acceleration sensor according to an embodiment of the present application; Figure 17 Figure 17 is a simulation schematic diagram of an acceleration sensor according to an embodiment of the present application.

[0023] Icon: 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 - protrusion; 110 - stop structure; 111 - movement space; 112 - avoidance space; 113 - first release hole; 114 - second release hole; 115 - support 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

[0024] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application 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.

[0025] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0026] It should be noted that: similar reference numbers 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 subsequent drawings. In addition, the terms "first", "second", "third" and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set", "mount", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0028] In the field of micro-electro-mechanical system (MEMS) technology, Z-axis high-g acceleration sensor is widely used in occasions that need to withstand large impact and high vibration environment, and its core function is to perceive acceleration changes through the off-plane motion of the mass in the Z direction. In order to improve the detection sensitivity of the sensor within the range of the range in the limited chip size, the spring beam stiffness is usually reduced. However, the reduction of spring beam stiffness will make the sensor more prone to structural damage when encountering over-range acceleration impact, thereby affecting its reliability and service life.

[0029] In order to solve the above problems, a stop structure is introduced in the acceleration sensor in the prior art, for example, a hard stop structure is arranged in the plane or out of the plane, which is used to limit the excessive displacement of the mass and prevent the spring beam from breaking due to excessive bending. However, in application, when the sensitive structure is subjected to 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.

[0030] In addition, the conventional stop structure often uses a machining process independent of the sensitive structure, increasing the process complexity and manufacturing cost.

[0031] To solve the above technical problems, the application provides an acceleration sensor preparation method and an acceleration sensor.

[0032] The speed sensor preparation method provided by the application comprises the following steps: Referring to Figure 1 As shown in the figure, 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; Referring to Figure 2 As shown in the figure, the first structure layer 103 is patterned and etched to form a protection structure 104 in a predetermined area; Referring to Figure 3 As shown in the figure, a second sacrificial layer 105 is deposited on the surface of the first structure layer 103; 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; Referring to Figure 4 As shown in the figure, 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; Referring to Figure 5 As shown in the figure, the second structure layer 108 is patterned and etched 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; Referring to Figure 6 As shown in the figure, the first sacrificial layer 101 and the second sacrificial layer 105 are released; specifically, 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.

[0033] It should be noted that the embodiment of the present application adopts a design mode of combining two structural layers with two sacrificial layer processes. Specifically, the first sacrificial layer 101 and the first structural layer 103 are sequentially deposited on the substrate 100, and the second sacrificial layer 105 and the second structural layer 108 are continuously deposited thereon. By defining structures in different layers and subsequently selectively releasing the sacrificial layers, the integration of multiple functional structures in the vertical direction is achieved. The multi-layer architecture of the embodiment of the present application not only helps to build a complex three-dimensional motion 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.

[0034] In order to simplify the manufacturing process and improve the consistency of the device, the present application proposes an integrated patterning and 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 patterning and etching the layer once; 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 embodiment 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 at the same time improves the integration and repeatability of the device.

[0035] It should be emphasized that the embodiment of the present application simultaneously obtains the fixed electrode 102 and the protection structure 104 on the first structural layer 103 by one patterning and etching. Similarly, the embodiment of the present application simultaneously obtains the mass electrode 107 and the stop structure 110 on the second structural layer 108 by one patterning and etching.

[0036] In order to solve the stress concentration problem in the contact and collision process between the stop structure 110 and the protection structure 104, the embodiment of the present application introduces a groove 106 in the process for forming a 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 within the projection range of the protection structure 104. When the mass electrode 107 moves, the protrusion 109 below 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 "soft stop" effect, thereby significantly reducing the damage risk caused by collision, and improving the stability and service life of the device in extreme impact environment.

[0037] In addition, since the mass electrode 107 and the fixed electrode 102 are at different potentials, if they are in direct contact, the device is prone to failure due to electrostatic attraction. By setting the protrusion 109, the protrusion 109 and the protection structure 104 are in an equipotential 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.

[0038] The first structure layer 103 and the second structure layer 108 can both 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. Hydrofluoric acid solution or gaseous hydrofluoric acid can be used to etch the silicon oxide of the first sacrificial layer 101 and the second sacrificial layer 105 to release part of the area.

[0039] 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.

[0040] First, 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 structure 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.

[0041] Second, by controlling the processing 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, there is no need for staged release, which can be completed in one release process. When the thickness difference between the first sacrificial layer 101 and the second sacrificial layer 105 is large, and the exposed areas of the silicon oxide of different layers are different, by adjusting the etching time and concentration of HF, the etching depth and range can be controlled, thereby realizing the staged release of different areas. 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.

[0042] In summary, by designing the release hole, controlling the processing parameters of hydrofluoric acid, and using the coordinated release strategy of multiple sacrificial layers, precise release of the first sacrificial layer 101 and the second sacrificial layer 105 is effectively realized, thereby ensuring the correct three-dimensional configuration and movement freedom of each functional structure in the sensor, and providing a solid guarantee for the realization of device performance and reliability.

[0043] It should be noted that the thickness of the polysilicon layer and the silicon oxide layer is not particularly limited herein, and those skilled in the art can set it according to the 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 structural layer 103 is 0.5-3 μm; and the thickness of the second structural layer 108 is 10-40 μm. The thickness of each layer can be controlled by the CMP process for planarization.

[0044] It should be noted that the distance between the protrusion 109 and the protection structure 104 can be designed by those skilled in the art according to the specific circumstances. For example, when the mass electrode 107 is not moving, the distance between the protrusion 109 and the protection structure 104 is 0.4-1.5 μm.

[0045] The technical effects that can be achieved by the embodiments of the present application are as follows: An integrated patterning and etching process is adopted to form multiple functional components, such as the fixed electrode 102 and the protection structure 104, the mass electrode 107 and the stop structure 110, in the same structural layer. 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, thereby reducing 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, thereby further controlling the manufacturing cost and being conducive to large-scale production and popularization and application.

[0046] The embodiments of the present application introduce the synergistic effect of the protection structure 104 and the stop structure 110, thereby significantly enhancing the structural stability of the sensor in a high-impact and large-vibration environment. When the mass block has 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 fracture of the spring beam 116 and structural adhesion, thereby improving the impact resistance and long-term stability of the device.

[0047] As an optional embodiment, the first structural layer 103 is patterned and etched to form the protection structure 104, which comprises: Referring to Figure 6 , Figure 7 It is shown that the first release hole 113 is formed on the protection structure 104 by patterning and etching.

[0048] Preferably, as shown in Figure 7 , the first release hole 113 has multiple and is uniformly and spacedly arranged 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.

[0049] In the embodiment of the present application, the first structural layer 103 is patterned and etched to form the fixed electrode 102 and the protection structure 104, and at the same time, a plurality of 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 under the protection structure 104 can be fully contacted and corroded to be removed, so as to realize the complete release of the region and form the required avoidance space 112.

[0050] The technical effects that can be achieved by the embodiment of the present application are as follows: on the one hand, a plurality of uniformly distributed release holes can improve the corrosion efficiency and ensure that the first sacrificial layer 101 under the protection structure 104 is fully removed, so as to avoid residual structure from being unable to suspend or being 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 formed at the same time as the protection structure 104, no additional processing steps are required, which helps to simplify the manufacturing process, reduce costs, and at the same time ensure the mechanical integrity and functional reliability of the overall structure.

[0051] As an optional embodiment, the second structural layer 108 is patterned and etched to form the stop structure 110, which includes: Referring to Figure 8 , Figure 9 It is shown that the second release hole 114 is formed on the mass electrode 107 and the stop structure 110 by patterned etching.

[0052] It should be noted that the second structural layer 108 is patterned and etched to form the mass electrode 107 and the stop structure 110, and at the same time, the second release hole 114 is etched on the mass electrode 107 and the stop structure 110. The second release hole 114 can be distributed on the second structural layer 108, and its purpose is to provide an effective corrosion channel for subsequent corrosion of the second sacrificial layer 105 by hydrofluoric acid. Through this design, the second sacrificial layer 105 located under the mass electrode 107 and the stop structure 110 can be fully contacted and removed, so as to form the required movement space 111 in the corresponding region, and ensure the free displacement of the mass and the function realization of the stop structure 110.

[0053] The technical effects of the embodiments of the present application can be: first, the second release holes 114 arranged on the mass electrode 107 and the stop structure 110 can significantly improve the uniformity and efficiency of the etching of the sacrificial layer, ensure the formation of a complete and consistent suspended area under the mass, and avoid the limitation of movement or device failure caused by the residual sacrificial layer; second, the reasonable layout of the release holes helps to reduce the blind area of etching, improve the consistency and reliability of the device. In addition, since the release holes are completed synchronously 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.

[0054] 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.

[0055] Further, the second structure layer 108 is patterned and etched to form the stop structure 110, including: Referring to Figure 10 As shown, the support column 115 and the spring beam 116 connecting the support column 115 and the mass electrode 107 are simultaneously formed on the second structure layer 108 by 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.

[0056] In the embodiments of the present application, in the process of patterning and etching the second structure layer 108, not only the mass electrode 107 and the stop structure 110 are formed, but also the support column 115 and the spring beam 116 connecting the support column 115 and the mass electrode 107 are simultaneously processed. Through this process step, multiple key functional components are completed at one time on the same structure layer.

[0057] It should be noted that no release hole is provided at the support column 115 and the edge portion near the support column 115 to avoid the etching of the sacrificial layer under the support column 115 by hydrofluoric acid. The support column 115 is connected with the substrate 100 through the sacrificial layer below, so as to form a reliable support structure after the release process. This integrated etching method does not need to set a separate processing flow for each structure, which significantly simplifies the manufacturing steps of the MEMS device and improves the consistency and alignment accuracy of the structure.

[0058] The technical effects of the embodiments of the present application are as follows: firstly, the mass block electrode 107, the stop structure 110, the support column 115 and the spring beam 116 are formed simultaneously by one-time patterning and etching, which not only effectively simplifies the manufacturing process, but also reduces the process complexity and production cost, and improves the mass production of the device; secondly, the formation of each functional structure in the same step helps to improve the consistency of the structure of the device, and further improves the performance stability of the sensor.

[0059] Referring to Figure 8 As an optional embodiment, 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, as shown in the figure; 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 for connecting the mass block electrode 107; the protrusion 109 is arranged on the side of the first floating island 117 close to the protection structure 104.

[0060] It should be noted that the arrangement of the cantilever beam 118 makes the first floating island 117 have a certain elasticity. When the mass block electrode 107 is subjected to a large impact (such as a hundred g acceleration), the protrusion 109 on the stop structure 110 contacts the protection structure 104 below, and the contact force is transmitted to the cantilever beam 118 through the first floating island 117, so that the cantilever beam 118 deforms and generates an elastic force to pull the protrusion 109 back, thereby reducing the kinetic energy of the first floating island 117 moving towards the protection structure 104. The greater the displacement of the protrusion 109 moving towards the protection structure 104, the greater the back-pulling elastic force generated by the cantilever beam 118, thereby achieving dynamic buffering. The embodiments of the present application make the stop structure 110 have elastic ability through the arrangement of the cantilever beam 118, and cooperate with the protection structure 104 to realize double elastic buffering, thereby effectively reducing the damage of large impact to the acceleration sensor structure.

[0061] It should be noted that the number of cantilever beams 118 is not particularly limited here. For example, there are four cantilever beams 118, and the first floating island 117 is a rectangular structure. The four cantilever beams 118 are arranged on the four side walls of the first floating island 117. For example, there are eight cantilever beams 118, two cantilever beams 118 extending in perpendicular directions are 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.

[0062] It should be noted that: first, the cantilever beam 118 gives 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, combined 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, the design of the embodiment of the present 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 present application can effectively improve the impact resistance and long-term reliability of the acceleration sensor.

[0063] Referring to Figure 7 As an optional implementation, the protection structure 104 includes a second floating island 119, an outer frame surrounding the second floating island 119 in the circumferential direction, and a plurality of spring folded beams 120 arranged in the circumferential direction 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 on the side close to the first floating island 117, and the projection 109 and the abutting portion are projected and overlapped on the substrate 100.

[0064] 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, ensuring accurate detection.

[0065] It should be noted that the protection structure 104 includes a second floating island 119 and a plurality of spring folded beams 120 arranged in the circumferential direction around it, which are composed of a plurality of S-shaped or arch-shaped structures connected in sequence, one end connected to the second floating island 119, and the other end extended and connected to the fixed electrode 102. An abutting portion is provided on the side of the second floating island 119 close to the first floating island 117 in the stop structure 110, and the projection position of the abutting portion and the projection 109 on the stop structure 110 on the substrate 100 is overlapped, ensuring that the two can accurately contact when extreme displacement occurs. This structure design not only gives the flexible protection structure 104 good elastic deformation ability, but also realizes greater deformation absorption space and more uniform stress distribution through the spring folded beam 120.

[0066] The spring folding beam 120 of the embodiment of the present application adopts a design of multiple S-shaped or arch-shaped structures connected in series, which significantly improves the elasticity range and buffering capacity of the flexible protection structure 104, so that it can effectively absorb energy when subjected to impact force and reduce damage to the sensor core components. The abutting portion on the second floating island 119 of the embodiment of the present application is precisely aligned with the protrusion 109 in the stop structure 110, achieving precise and reliable contact control and avoiding stress concentration or functional failure due to misalignment; the flexible protection structure 104 cooperates with the stop structure 110 of the first floating island 117 with a cantilever beam 118 to jointly build a double-elastic buffering mechanism, further enhancing the stability and reliability of the sensor in a high-impact environment, thereby significantly improving the overall performance and service life of the device.

[0067] Figure 12 、 Figure 13 The simulation result of the acceleration sensor without the protection structure 104 and the stop structure 110. When there is no protection structure 104, the mass block is displaced by the inertial force, and the stress of the hard limiting protrusion colliding with the substrate block is 351 MPa, which is close to the allowable stress of silicon material and has the risk of breaking.

[0068] Figure 14 、 Figure 15 The simulation result after adding the protection structure 104 in the embodiment of the present application. The stress of the protrusion 109 below the stop structure 110 is reduced to 120 MPa, which is 65% lower than the collision stress of the prior art without the protection structure; at the same time, the stress of the spring folding beam 120 is 130 MPa, which is much lower than the allowable stress of silicon material, and the structural safety is improved.

[0069] Figure 16 、 Figure 17 The simulation result after setting the protection structure 104 and the stop structure 110 in the embodiment of the present application. Referring to Figure 17 , when the protection structure 104 and the stop structure 110 are added, the eight cantilever beams disperse most of the stress of the protrusion 109 collision, so that the stress of the protrusion 109 collision itself is only 25 MPa, which is Figure 15 80% lower than the prior art without the protection structure, greatly reducing the collision stress of the protrusion 109 and having strong environmental reliability, so that the Z-axis acceleration sensor can adapt to most large dynamic ranges or extreme environments without failure.

[0070] Referring to Figure 6 、 Figure 10As shown, the acceleration sensor provided in the application comprises a substrate 100, and a first structure layer 103 and a second structure layer 108 arranged on the substrate 100 in sequence; 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 is preset at a distance from the fixed electrode 102 and the projection of the mass electrode 107 on the substrate 100 at least partially overlaps; the projection of the stop structure 110 on the substrate 100 at least partially overlaps with the projection of the protection structure 104; the stop structure 110 is provided with a protrusion 109 on the side close to the protection structure 104; the protection structure 104 and the substrate 100 have a clearance space 112 therebetween; when the mass electrode 107 is forced to move close to the substrate 100, the protrusion 109 abuts against the protection structure 104, so that the protection structure 104 is elastically deformed.

[0071] Among them, the fixed electrode 102 and the protection structure 104 are in the same level; the mass electrode 107 and the stop structure 110 are also in the same level, and the structures in the same level can be obtained in one-time patterning etching.

[0072] The acceleration sensor provided in the embodiment of the application sets the protrusion 109 on the side of the stop structure 110 close to the protection structure 104, and makes the projection of the protrusion 109 on the substrate 100 at least partially overlap with the projection of the protection structure 104, so as to ensure that when the mass electrode 107 is forced to move towards the substrate 100, the protrusion 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 arranged between the protection structure 104 and the substrate 100, so that the protection structure 104 has the elastic deformation capability and is elastically deformed when the protrusion 109 applies pressure, thereby absorbing the impact energy. The 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 enhances the stability and service life of the device through the elastic buffering mechanism.

[0073] Among them, 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, the other end 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.

[0074] Referring to Figure 11 As an optional embodiment, the elastic buffering structure 121 is arranged between the support column 115 and the mass electrode 107; the elastic force generated by the deformation of the elastic buffering structure 121 is perpendicular to the elastic force generated by the deformation of the protection structure 104.

[0075] 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 design of the structure makes the elastic force generated by the structure perpendicular to the elastic force generated by the protection structure 104 when the protection structure 104 deforms. That means, in addition to the original protection mechanism in the direction along the Z axis (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 to the fixed electrode 102 due to impact and moves a certain degree, the elastic buffer structure 121 can effectively absorb the energy of the unexpected lateral movement, preventing the mass electrode 107 from colliding with other components directly.

[0076] The embodiments of the present application ensure that not only excessive impact force can 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, more comprehensive mechanical protection can be provided without interfering with the original function.

[0077] Referring to Figure 9 As an optional embodiment, the spring beam 116 is arranged on the opposite two sides of the support column 115, and the elastic buffer structure 121 is arranged on the other opposite two sides of the support column 115.

[0078] The spatial layout of the embodiments of the present application makes the spring beam 116 and the elastic buffer structure 121 bear different mechanical functions in different directions. Among them, 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.

[0079] 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 unexpected collision risk caused by the lateral displacement of the mass electrode 107. In addition, this symmetrical and functionally separated structure 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.

[0080] As an optional embodiment, the mass electrode 107 includes a first negative electrode and a first positive electrode arranged on the two sides of the extension direction of the spring beam 116, respectively; 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.

[0081] Among them, there are two groups of protection structures 104 symmetrically arranged 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.

[0082] It should be noted that the mass 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 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 electrode 107, that is, the mass 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.

[0083] 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 improve the recognition ability of the sensor to small acceleration changes, and enhance the anti-interference performance; second, the positive and negative electrodes form independent capacitance pairs with the corresponding fixed electrodes 102, which is conducive to improving the linearity and accuracy of signal acquisition, thereby optimizing the overall performance of the sensor; in addition, the electrode structure is combined with the aforementioned multi-directional elastic buffering mechanism, which not only guarantees 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.

[0084] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles 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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