MEMS piezoelectric system, MEMS piezoelectric device and preparation method thereof

Abstract

The invention provides an MEMS piezoelectric system, an MEMS piezoelectric device and a preparation method thereof, and relates to the technical field of semiconductors. The MEMS piezoelectric device comprises a base and a piezoelectric cantilever beam arranged on the base, the base is provided with a through cavity, the through cavity penetrates through a first surface and a second surface which are opposite to each other, a fixed area of the piezoelectric cantilever beam is connected with the first surface of the base, and a free area of the piezoelectric cantilever beam is suspended above the through cavity; at least one through cavity corresponds to two or more piezoelectric cantilever beams which are arranged at an included angle, and the free area of at least one piezoelectric cantilever beam is bent in the direction close to or away from the through cavity. The MEMS piezoelectric device can sense changes of external physical quantities in two or three directions, and a working shaft is changed into double shafts or three shafts from a single shaft in the prior art.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a MEMS piezoelectric system, a MEMS piezoelectric device, and a method for manufacturing the same. Background Art

[0002] Micro-Electro-Mechanical Systems (MEMS) piezoelectric cantilever beams are the key basic structures in MEMS piezoelectric devices and systems and can be used in switches, resonators, sensors, etc. From a structural point of view, please refer to Figure 1 One end of the MEMS piezoelectric cantilever beam 10 is fixed to the base 20, defined as the fixed end 11, while the other end, which is suspended above the through-hole 21 of the base 20 and can vibrate or bend freely, is defined as the free end 12. In addition, the size of the MEMS piezoelectric cantilever beam 10 in the first direction Z is usually much smaller than the size in the second direction X and the third direction Y. When external physical quantities (such as pressure, sound pressure, temperature, etc.) act on the MEMS piezoelectric cantilever beam 10, it will produce tiny deformations, displacement changes, stress changes, and other responses. Through the piezoelectric effect, these physical quantities can be converted into electrical signals, thereby realizing the sensing and detection of various physical quantities.

[0003] Figure 2 It corresponds to Figure 1 Schematic diagram of external force / acceleration change and output charge / output voltage of piezoelectric cantilever. Since the MEMS piezoelectric cantilever 10 is usually suspended horizontally above the through cavity 21, and the size in the first direction Z is much smaller than the size in the second direction X and the third direction Y, the MEMS piezoelectric cantilever 10 is only sensitive to the change of physical quantity in the first direction Z, and is extremely insensitive to the change of physical quantity in the second direction X and the third direction Y. Figure 1 The MEMS piezoelectric cantilever 10 shown is only capable of uniaxial operation. Summary of the Invention

[0004] The purpose of this application is to address the deficiencies in the above-mentioned prior art and provide a MEMS piezoelectric system, a MEMS piezoelectric device and a preparation method thereof, which can sense changes in external physical quantities in two or three directions and realize two-axis or three-axis operation.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of the present application are as follows: In one aspect of an embodiment of the present application, a MEMS piezoelectric device is provided, comprising: a base and a piezoelectric cantilever beam arranged on the base, the base being provided with a through cavity, the through cavity penetrating a first surface and a second surface opposite to each other of the base, a fixed area of ​​the piezoelectric cantilever beam being connected to the first surface of the base, and a free area of ​​the piezoelectric cantilever beam being suspended above the through cavity; at least one through cavity corresponds to two or more piezoelectric cantilever beams arranged at an angle, wherein the free area of ​​at least one piezoelectric cantilever beam is bent toward or away from the through cavity.

[0006] Optionally, at least one through cavity corresponds to two or more vertically arranged piezoelectric cantilever beams.

[0007] Optionally, the free area of ​​the curved piezoelectric cantilever beam is divided into at least one curved portion, the surface of the curved portion is an arc surface, and the curved portion extends to two opposite sides of the free area.

[0008] Optionally, along the sequential arrangement direction of the fixed area and the free area, the free area of ​​the curved piezoelectric cantilever beam is curved in a wave-like manner.

[0009] Optionally, a free region of the bent piezoelectric cantilever beam is bent away from a corner of the fixed region toward or away from the through cavity.

[0010] Optionally, a weight block is provided on the free area of ​​at least part of the piezoelectric cantilever beam, and the weight block is used to bend the free area or adjust the performance of the MEMS piezoelectric device.

[0011] On the other hand, an embodiment of the present application provides a method for preparing a MEMS piezoelectric device, comprising: providing a base layer and forming a vibration membrane layer on the base layer; adjusting the tensile stress distribution and / or compressive stress distribution of the vibration membrane layer according to the structure of the piezoelectric cantilever beam to be prepared, so that the stress in the first area on the vibration membrane layer is different from the stress in the second area, wherein the first area is used to form a bent area of ​​a bent piezoelectric cantilever beam, and the second area is used to form an unbent area of ​​a bent piezoelectric cantilever beam or a straight piezoelectric cantilever beam; etching the vibration membrane layer and forming a through cavity on the base layer that passes through the upper and lower surfaces of the base layer to obtain a MEMS piezoelectric device, wherein at least one through cavity of the MEMS piezoelectric device corresponds to two or more piezoelectric cantilever beams set at an angle, and the free area of ​​at least one piezoelectric cantilever beam is bent in a direction close to or away from the through cavity.

[0012] Optionally, the preparation method includes: performing structural design of a MEMS piezoelectric device and performing process design based on the structural design; forming a base layer based on the structural design and process design, and forming a vibration membrane layer on the base layer; regulating the film growth mode, film composition and / or film microstructure of the vibration membrane layer based on the structural design and process design to regulate the tensile stress distribution and / or compressive stress distribution of the vibration membrane layer, so that the stress in the first area on the vibration membrane layer is different from the stress in the second area, wherein the first area is used to form a bent area of ​​a bent piezoelectric cantilever beam of the MEMS piezoelectric device, and the second area is used to form an unbent area of ​​the bent piezoelectric cantilever beam or a straight piezoelectric cantilever beam; etching the vibration membrane and forming a through cavity on the base layer that passes through the upper and lower surfaces of the base layer to obtain a MEMS piezoelectric device, wherein at least one through cavity of the MEMS piezoelectric device corresponds to two or more piezoelectric cantilevers set at an angle, and the free area of ​​at least one piezoelectric cantilever beam is bent in a direction close to or away from the through cavity.

[0013] Optionally, the structural design includes the selection of base material, base structure design, piezoelectric cantilever shape design, and the selection and design of multilayer films in the piezoelectric cantilever; the process design includes the design of film growth or deposition process parameters, the design of piezoelectric cantilever preparation process parameters, and the design of piezoelectric cantilever post-processing process parameters.

[0014] According to another aspect of the embodiments of the present application, a MEMS piezoelectric system is provided, comprising the MEMS piezoelectric device according to any one of the above items.

[0015] The beneficial effects of this application include: The present application provides a MEMS piezoelectric device, comprising: a base and a piezoelectric cantilever beam disposed on the base; the base is provided with a through-cavity extending through first and second opposing surfaces of the base; the fixed region of the piezoelectric cantilever beam is connected to the first surface of the base, and the free region of the piezoelectric cantilever beam is suspended above the through-cavity; at least one through-cavity corresponds to two or more piezoelectric cantilever beams disposed at an angle, wherein the free region of at least one piezoelectric cantilever beam bends toward or away from the through-cavity. The MEMS piezoelectric device can sense changes in external physical quantities in two or three directions, and the operating axis is changed from the single axis of the prior art to a dual or triaxial one. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 is a cross-sectional view of an existing piezoelectric cantilever beam structure; Figure 2 To correspond Figure 1 Schematic diagram of the external force / acceleration change and the output charge / output voltage of the piezoelectric cantilever; Figure 3 One of the structural schematic diagrams of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 4 The second structural diagram of the MEMS piezoelectric device provided in the embodiment of the present application; Figure 5 The third structural diagram of the MEMS piezoelectric device provided in the embodiment of the present application; Figure 6 To correspond Figure 3 Schematic diagram of the external force / acceleration change and the output charge / output voltage of the piezoelectric cantilever; Figure 7 One of the cross-sectional views of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 8 The second cross-sectional view of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 9 The fourth structural diagram of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 10 The third cross-sectional view of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 11 This is a fourth cross-sectional view of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 12 One of the top views of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 13 A second top view of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 14 The fifth cross-sectional view of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 15 A sixth cross-sectional view of the MEMS piezoelectric device provided in an embodiment of the present application; Figure 16 One of the flow charts of the method for preparing a MEMS piezoelectric device provided in an embodiment of the present application; Figure 17 Schematic diagram of the preparation process of the MEMS piezoelectric device provided in the embodiment of the present application; Figure 18 This is the second flow chart of the method for preparing a MEMS piezoelectric device provided in an embodiment of the present application.

[0018] Icon: 10-MEMS piezoelectric cantilever beam; 11-fixed end; 12-free end; 20-base; 21-through cavity; 100-MEMS piezoelectric device; 110-base; 111-through cavity; 120-piezoelectric cantilever beam; 121-fixed area; 122-free area; 1221-straight part; 1222-curved part; 123-free end; 124-membrane layer; 130-weight block; 200-base layer; 300-vibrating membrane layer; 400-thin film; X-second direction; Y-third direction; Z-first direction. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application as claimed, but merely represents selected embodiments of the present application. It should be noted that, unless there is a conflict, the various features of the embodiments of the present application may be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0022] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of this application is typically placed when in use. These terms are intended only to facilitate the description of this application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0024] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0025] In one aspect of the embodiment of this application, please refer to Figure 3 , provides a MEMS piezoelectric device 100 including: a base 110 and a piezoelectric cantilever beam 120.

[0026] The base 110 is provided with a through cavity 111, which extends through the first and second opposing surfaces of the base 110, thereby giving the base 110 an annular shape. The number of through cavities 111 can be one, two, or more. When there are two or more through cavities 111, each through cavity 111 is independent and not interconnected.

[0027] The piezoelectric cantilever beam 120 is disposed on the first surface of the base 110. The fixed region 121 of the piezoelectric cantilever beam 120 is connected to the first surface of the base 110, and the free region 122 of the piezoelectric cantilever beam 120 is suspended above one of the through cavities 111 of the base 110. The end of the free region 122 away from the fixed region 121 is the free end 123 of the piezoelectric cantilever beam 120.

[0028] A piezoelectric cantilever beam 120 is disposed above each through cavity 111 on the base 110, but the number of piezoelectric cantilever beams 120 above each through cavity 111 may be equal or unequal. At least one through cavity 111 on the base 110 corresponds to two or more piezoelectric cantilever beams 120 disposed at an angle, wherein the free area 122 of at least one piezoelectric cantilever beam 120 is bent toward or away from the through cavity 111. In other words, there are two or more piezoelectric cantilever beams 120 corresponding to at least one through cavity 111 on the base 110, and these piezoelectric cantilever beams 120 are not all parallel to each other. There are piezoelectric cantilever beams 120 with an angle greater than 0° and less than 180°, and at least one of the two or more piezoelectric cantilever beams 120 is bent.

[0029] For example, Figure 3 As shown, two piezoelectric cantilever beams 120 are correspondingly provided on a through cavity 111, the angle between the two piezoelectric cantilever beams 120 is 90 degrees and both piezoelectric cantilever beams 120 are bent. Figure 4As shown, six piezoelectric cantilever beams 120 are correspondingly provided on a through cavity 111. These six piezoelectric cantilever beams 120 are divided into two groups. The piezoelectric cantilever beams 120 in the same group are parallel to each other, and any two piezoelectric cantilever beams 120 in different groups are perpendicular to each other. All six piezoelectric cantilever beams 120 are bent. For another example, Figure 5 As shown, two piezoelectric cantilever beams 120 are correspondingly provided on a through cavity 111 , and the angle between the two piezoelectric cantilever beams 120 is 90°, wherein one piezoelectric cantilever beam 120 is bent and the other piezoelectric cantilever beam 120 is straight.

[0030] It should be noted that there are three possible situations for the piezoelectric cantilever beam 120 disposed above a through cavity 111: first, only a curved piezoelectric cantilever beam 120 is disposed above the through cavity 111; second, only a straight piezoelectric cantilever beam 120 is disposed above the through cavity 111; and third, both a curved piezoelectric cantilever beam 120 and a straight piezoelectric cantilever beam 120 are disposed above the through cavity 111. If there is a curved piezoelectric cantilever beam 120, the free region 122 of the curved piezoelectric cantilever beam 120 will be in a curved state when there is no external physical quantity acting on it, and the bending position, angle, and number of times can be arbitrary.

[0031] Please refer to Figure 1 、 Figure 2 and Figure 6 The straight piezoelectric cantilever beam 120 can only sense changes in external physical quantities in the first direction Z, but the curved piezoelectric cantilever beam 120 can not only sense changes in external physical quantities in the first direction Z, but also sense changes in external physical quantities in the second direction X and / or the third direction. Therefore, for a MEMS piezoelectric device, as long as there is a curved piezoelectric cantilever beam 120 on a through cavity 111 on its base 110, it can sense external physical quantities in two or three directions, and the number of working axes is two or three.

[0032] by Figure 3 Taking the corresponding embodiment as an example, one of the piezoelectric cantilever beams 120 can sense changes in external physical quantities in the first direction Z and the third direction Y due to bending, and the other piezoelectric cantilever beam 120 can sense physical quantities in the first direction Z and the second direction X due to bending. The two piezoelectric cantilever beams 120 are combined together to sense changes in external physical quantities in three directions, so that the working axis of the MEMS piezoelectric device 100 is changed from a single axis in the prior art to a three-axis.

[0033] The above-mentioned MEMS piezoelectric device 100 is provided with at least two piezoelectric cantilever beams 120 with an angle above the same through cavity 111. There is at least one bent piezoelectric cantilever beam 120 among the at least two piezoelectric cantilever beams 120 arranged at an angle, so that the above-mentioned MEMS piezoelectric device 100 can sense changes in external physical quantities in two or three directions, and the working axis is changed from the single axis of the prior art to two axes or three axes.

[0034] Generally speaking, the MEMS piezoelectric device 100 needs to sense external physical quantities in three mutually perpendicular directions. To improve sensing sensitivity, at least one through-cavity 111 optionally corresponds to two or more perpendicularly arranged piezoelectric cantilever beams 120. In other words, the angle between the two piezoelectric cantilever beams 120 is 90°. In this case, the MEMS piezoelectric device 100 has the highest sensitivity to external physical quantities in the three mutually perpendicular directions.

[0035] Several optional embodiments of bending the free area 122 of the piezoelectric cantilever beam 120 are given below: Alternatively, see Figure 3 and Figure 7 The free area 122 of the curved piezoelectric cantilever beam 120 is divided into at least one curved portion 1222 . The surface of the curved portion 1222 is an arc surface, and the curved portion 1222 extends to two opposite sides of the free area 122 .

[0036] The curved portion 1222 of the curved piezoelectric cantilever beam 120 extends to opposite sides of the free region 122, thereby bending the entire free region 122 toward or away from the through cavity 111. In this case, the curved piezoelectric cantilever beam 120 can sense external physical quantities in the first direction Z and the second direction X, or in the first direction Z and the third direction Y. Furthermore, the overall curvature of the free region 122 can also enhance the sensitivity of the MEMS device.

[0037] Figure 7 The piezoelectric cantilever beam 120 is bent toward the through cavity 111. Figure 7 From the perspective of , it is reflected that the piezoelectric cantilever beam 120 is bent downward as a whole. Then, the piezoelectric cantilever beam 120 is bent in the direction away from the through cavity 111 as a whole. Figure 7 From the same perspective, the piezoelectric cantilever beam 120 should be bent upward as a whole.

[0038] Furthermore, the free area 122 is further divided into a straight portion 1221 connected to the curved portion 1222 , and the surface of the straight portion 1221 is a plane.

[0039] Preferably, there is a smooth transition between the curved portion 1222 and the straight portion 1221 , thereby avoiding the formation of obvious creases on the free area 122 that would affect the performance of the piezoelectric cantilever beam 120 .

[0040] Alternatively, see Figure 8 Along the sequential arrangement direction of the fixed area 121 and the free area 122 , the free area 122 of the curved piezoelectric cantilever beam 120 is curved in a wave-like manner.

[0041] In this embodiment, the free area 122 bends both toward the through cavity 111 and away from the through cavity 111 . This bending method can also achieve measurement of external physical quantities in two directions.

[0042] Alternatively, see Figure 9 A corner of the free region 122 of the bent piezoelectric cantilever beam 120 away from the fixed region 121 bends toward or away from the through cavity 111 .

[0043] Figure 9 One corner of the piezoelectric cantilever beam 120 shown in the figure is bent in a direction away from the through cavity 111. In other embodiments, one corner of the piezoelectric cantilever beam 120 may also be bent in a direction close to the through cavity 111, or one corner may be bent in a direction away from the through cavity 111 and the other corner may be bent in a direction close to the through cavity 111.

[0044] The bending of one corner of the free area 122 allows a piezoelectric cantilever beam 120 to sense external physical quantities in three directions. However, compared with the solution in which the free area 122 is bent upward or downward as a whole, its sensing sensitivity is relatively weak.

[0045] Alternatively, see Figure 10 and Figure 11 A weight block 130 is provided on at least a portion of the free area 122 of the piezoelectric cantilever beam 120 . The weight block 130 is used to bend the free area 122 or adjust the performance of the MEMS piezoelectric device 100 .

[0046] The provision of the weight block 130 increases the weight of a local area of ​​the free region 122 and can adjust the tensile stress and / or compressive stress in a portion of the piezoelectric cantilever beam 120, thereby causing the free region 122 to bend. This bending can be the entire free region 122 or a corner of the free region 122. The weight block 130 can also be used to adjust the performance of the MEMS piezoelectric device 100, such as its output sensitivity, frequency, etc.

[0047] It should be noted that the weight block 130 can be disposed above or below the piezoelectric cantilever beam 120. The weight block 130 can be implemented by locally thickening the membrane layer 124 of the piezoelectric cantilever beam 120, or can be an additional block added to the piezoelectric cantilever beam 120.

[0048] Furthermore, the weight block 130 is disposed at the free end 123 of the piezoelectric cantilever beam 120. The weight block 130 is disposed at the free end 123 to better bend the free region 122 of the cantilever beam or adjust the performance of the MEMS piezoelectric device 100.

[0049] It should be noted that Figures 7 to 11 Although only one bent piezoelectric cantilever beam 120 is shown in FIG, this does not mean that the MEMS device only has this one piezoelectric cantilever beam 120. It is just that the other piezoelectric cantilever beams 120 are not shown. Only one piezoelectric cantilever beam 120 is shown to more clearly illustrate the bending mode of a single piezoelectric cantilever beam 120.

[0050] In addition, the cross section of the piezoelectric cantilever beam 120 may be rectangular (e.g. Figure 3 As shown), trapezoid, triangle (as Figure 12 as shown) or heteromorphic (as Figure 13 shown) etc.

[0051] In a piezoelectric cantilever beam 120, the number of the film layers 124 can be multiple, and the multiple film layers 124 can completely overlap (e.g. Figure 14 As shown in ), some areas may also overlap (as shown in Figure 15 As shown). The multilayer film layer 124 can be, from bottom to top, a connection layer, an electrode layer, a piezoelectric layer, and an electrode layer, or can be, from bottom to top, an electrode layer, a piezoelectric layer, an electrode layer, a piezoelectric layer, and an electrode layer. The electrode layer can be any thin film material capable of leading out the electrical signal of the MEMS piezoelectric device, including but not limited to metal films (such as Pt, Au, Mo, Cu, Ta, etc.), semiconductor films (such as Ge, Si, etc.), compounds and oxides (such as SnSc, SiC, MnCo, TaN, etc.), and various conductive composite film materials; the piezoelectric layer material can be piezoelectric thin film materials such as aluminum nitride (AlN), scandium-doped aluminum nitride (AlScN), lead zirconate titanate (PZT), lithium niobate (LiNbO3), potassium sodium niobate (KNN), and polyvinylidene fluoride (PVDF); the connection layer can be silicon, silicon oxide, or the electrode layer materials or piezoelectric layer materials mentioned above.

[0052] Another aspect of the present invention is to refer to Figure 16 , provides a method for preparing a MEMS piezoelectric device, comprising: S100: providing a base layer, and forming a vibration membrane layer on the base layer.

[0053] Please refer to Figure 17 The base layer 200 is generally a silicon wafer, and the vibration membrane layer 300 is generally formed by stacking multiple layers of thin films 400. Figure 3 and Figure 14 The base layer 200 is used to form the base 110 of the MEMS piezoelectric device 100, the vibration membrane layer 300 is used to form the piezoelectric cantilever beam 120 of the MEMS piezoelectric device 100, and the thin films 400 in the vibration membrane layer 300 are used to form the electrode layer, piezoelectric layer or connecting layer of the piezoelectric cantilever beam 120, wherein the piezoelectric cantilever beam 120 at least includes a curved piezoelectric cantilever beam 120, and can further include a straight piezoelectric cantilever beam 120.

[0054] S200: Adjust the tensile stress distribution and / or compressive stress distribution of the vibration membrane layer according to the structure of the piezoelectric cantilever beam to be prepared, so that the stress in the first area on the vibration membrane layer is different from the stress in the second area, wherein the first area is used to form a bent area of ​​a bent piezoelectric cantilever beam, and the second area is used to form an unbent area of ​​a bent piezoelectric cantilever beam or a straight piezoelectric cantilever beam.

[0055] Please refer to Figure 3 Before fabrication, the base 110 and piezoelectric cantilever beam 120 of the MEMS piezoelectric device 100 are designed. Then, based on the bending scheme of the piezoelectric cantilever beam 120, the tensile stress distribution, the compressive stress distribution, or both of the tensile and compressive stress distributions of the diaphragm layer 300 are adjusted. The goal is to create two regions of differing stress on the diaphragm layer 300. This way, when the piezoelectric cantilever beam 120 is subsequently released, it will bend.

[0056] S300: Etching the vibration membrane layer and forming a through cavity on the base layer that penetrates the upper surface and the lower surface of the base layer to obtain a MEMS piezoelectric device, wherein at least one through cavity of the MEMS piezoelectric device corresponds to two or more piezoelectric cantilever beams arranged at an angle, and the free area of ​​at least one piezoelectric cantilever beam is bent toward or away from the through cavity.

[0057] The above-mentioned method for preparing the MEMS piezoelectric device regulates the growth mode, composition and microstructure of the thin film in the vibration membrane layer 300, such as lattice orientation, grain size, and film surface roughness, through structural design and process design, thereby regulating the distribution of tensile stress and / or compressive stress in the entire or partial area of ​​the piezoelectric cantilever beam 120, and thus obtaining the MEMS piezoelectric device 100 in the aforementioned embodiment. Among them, the structural design includes the selection and design of the base 110, the shape design of the piezoelectric cantilever beam 120, the selection and design of the multilayer film of the piezoelectric cantilever beam 120, etc. The process design includes the design of film growth or deposition process parameters, the design of piezoelectric cantilever beam 120 preparation process parameters, and the design of the post-processing process of the piezoelectric cantilever beam 120.

[0058] The MEMS piezoelectric device 100 prepared by the above-mentioned method for preparing a MEMS piezoelectric device has at least two piezoelectric cantilever beams 120 with an angle arranged above the same through cavity 111. There is at least one curved piezoelectric cantilever beam 120 among the at least two piezoelectric cantilever beams 120 arranged at an angle. Therefore, it can sense changes in external physical quantities in two or three directions, and the working axis is changed from the single axis of the existing technology to dual axis or tri-axis.

[0059] Alternatively, see Figure 18 , the preparation method comprises: S110: Perform structural design of the MEMS piezoelectric device and perform process design based on the structural design.

[0060] S120: forming a base layer according to the structural design and process design, and forming a vibration membrane layer on the base layer.

[0061] S130: Regulate the film growth mode, film composition and / or film microstructure of the vibration membrane layer according to the structural design and process design to regulate the tensile stress distribution and / or compressive stress distribution of the vibration membrane layer, so that the stress in the first area on the vibration membrane layer is different from the stress in the second area, wherein the first area is used to form a bent area of ​​a bent piezoelectric cantilever beam of a MEMS piezoelectric device, and the second area is used to form an unbent area of ​​the bent piezoelectric cantilever beam or a straight piezoelectric cantilever beam.

[0062] S140: Etching the vibration membrane and forming a through cavity on the base layer that penetrates the upper surface and the lower surface of the base layer to obtain a MEMS piezoelectric device, wherein at least one through cavity of the MEMS piezoelectric device corresponds to two or more piezoelectric cantilever beams arranged at an angle, and the free area of ​​at least one piezoelectric cantilever beam is bent toward or away from the through cavity.

[0063] Please refer to Figure 3The desired MEMS piezoelectric device 100 is designed based on the requirements, and a process design for the MEMS piezoelectric device 100 is formulated based on the structural design. The base layer 200 and the vibration membrane layer 300 are then formed based on the structural and process designs. The base layer 200 and the vibration membrane layer 300 are then etched to obtain the desired MEMS piezoelectric device 100.

[0064] It should be noted that the aforementioned control parameters are not limited to the three categories of film growth mode, film composition, and film microstructure. The parameters that can be controlled at a single time can include one, two, or more of the three categories. More specifically, the control parameters can include lattice orientation, grain size, and film surface roughness.

[0065] Optionally, the structural design includes base material selection, base structure design, piezoelectric cantilever shape design, and selection and design of multilayer films in the piezoelectric cantilever; Process design: including thin film growth or deposition process parameter design, piezoelectric cantilever preparation process parameter design, and piezoelectric cantilever post-processing process parameter design.

[0066] Optionally, the vibration membrane layer 300 includes a plurality of stacked films 400 .

[0067] Adjusting the tensile stress distribution and / or compressive stress distribution of the vibration membrane layer according to the structure of the piezoelectric cantilever beam to be prepared includes: The tensile stress and / or compressive stress distribution of each film layer is adjusted respectively according to the structure of the piezoelectric cantilever beam to be prepared.

[0068] When the vibration membrane layer includes a plurality of thin films 400 , the tensile stress and / or compressive stress distribution of each thin film 400 can be adjusted to adjust the tensile stress and / or compressive stress distribution of the entire vibration membrane layer.

[0069] In another aspect of the embodiments of the present application, a MEMS piezoelectric system is provided, comprising the MEMS piezoelectric device 100 as described above.

[0070] The MEMS piezoelectric system includes the same structure and benefits as the MEMS piezoelectric device 100 in the aforementioned embodiment. The structure and benefits of the MEMS piezoelectric device 100 have been described in detail in the aforementioned embodiment and will not be repeated here.

[0071] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A MEMS piezoelectric device, characterized in that: include: A base and a piezoelectric cantilever beam disposed on the base, wherein the base is provided with a through cavity, the through cavity penetrating a first surface and a second surface opposite to the base, a fixed region of the piezoelectric cantilever beam being connected to the first surface of the base, and a free region of the piezoelectric cantilever beam being suspended above the through cavity; At least one of the through-cavities corresponds to two or more of the piezoelectric cantilever beams arranged at an angle, wherein the free area of ​​at least one of the piezoelectric cantilever beams is bent in a direction approaching or away from the through-cavity.

2. The MEMS piezoelectric device according to claim 1, wherein: At least one of the through cavities corresponds to two or more vertically arranged piezoelectric cantilever beams.

3. The MEMS piezoelectric device according to claim 1, wherein: The free area of ​​the curved piezoelectric cantilever beam is divided into at least one curved portion, the surface of the curved portion is an arc surface, and the curved portion extends to two opposite sides of the free area.

4. The MEMS piezoelectric device according to claim 1, wherein: Along the sequential arrangement direction of the fixed area and the free area, the free area of ​​the curved piezoelectric cantilever beam is curved in a wave-like manner.

5. The MEMS piezoelectric device according to claim 1, wherein: The free area of ​​the bent piezoelectric cantilever beam is bent away from a corner of the fixed area toward or away from the through cavity.

6. The MEMS piezoelectric device according to claim 1, wherein: A weight block is provided on the free area of ​​at least part of the piezoelectric cantilever beam, and the weight block is used to bend the free area or adjust the performance of the MEMS piezoelectric device.

7. A method for preparing a MEMS piezoelectric device, characterized in that: include: Providing a base layer, and forming a vibration membrane layer on the base layer; Adjusting the tensile stress distribution and / or compressive stress distribution of the vibration membrane layer according to the structure of the piezoelectric cantilever beam to be prepared, so that the stress in a first area and the stress in a second area on the vibration membrane layer are different, wherein the first area is used to form a curved area of ​​the curved piezoelectric cantilever beam, and the second area is used to form an unbent area of ​​the curved piezoelectric cantilever beam or a straight piezoelectric cantilever beam; The vibration membrane layer is etched and a through cavity is formed on the base layer, which passes through the upper surface and the lower surface of the base layer, so as to obtain a MEMS piezoelectric device, wherein at least one of the through cavities of the MEMS piezoelectric device corresponds to two or more piezoelectric cantilever beams arranged at an angle, and the free area of ​​at least one of the piezoelectric cantilever beams is bent toward or away from the through cavity.

8. The method for preparing a MEMS piezoelectric device according to claim 7, wherein: The preparation method comprises: Conduct structural design of MEMS piezoelectric devices and perform process design based on the structural design; forming a base layer according to the structural design and the process design, and forming a vibration membrane layer on the base layer; Regulating the film growth mode, film composition and / or film microstructure of the vibration membrane layer according to the structural design and the process design to regulate the tensile stress distribution and / or compressive stress distribution of the vibration membrane layer, so that the stress in a first area and the stress in a second area on the vibration membrane layer are different, wherein the first area is used to form a bent area of ​​a bent piezoelectric cantilever beam of the MEMS piezoelectric device, and the second area is used to form an unbent area of ​​the bent piezoelectric cantilever beam or a straight piezoelectric cantilever beam; The vibration membrane is etched and a through cavity is formed on the base layer, which passes through the upper surface and the lower surface of the base layer, so as to obtain a MEMS piezoelectric device, wherein at least one of the through cavities of the MEMS piezoelectric device corresponds to two or more piezoelectric cantilever beams arranged at an angle, and the free area of ​​at least one piezoelectric cantilever beam is bent toward or away from the through cavity.

9. The method for preparing a MEMS piezoelectric device according to claim 8, wherein: The structural design includes base material selection, base structure design, piezoelectric cantilever beam shape design, and selection and design of multilayer films in the piezoelectric cantilever beam; The process design includes the design of thin film growth or deposition process parameters, the design of piezoelectric cantilever preparation process parameters, and the design of piezoelectric cantilever post-processing process parameters.

10. A MEMS piezoelectric system, characterized in that: The device comprises the MEMS piezoelectric device according to any one of claims 1 to 6.

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