Piezoelectric element and preparation method thereof, piezoelectric device and electronic equipment

Abstract

The embodiment of the invention provides a piezoelectric element and a preparation method thereof, a piezoelectric device and electronic equipment, relates to the technical field of semiconductor devices, and is used for reducing the manufacturing error of the piezoelectric element and improving the uniformity of the piezoelectric element. The piezoelectric element includes a substrate, a vibration plate, and a plurality of piezoelectric elements. The substrate is provided with a plurality of cavities penetrating through the substrate in the thickness direction, and the cavities are sequentially arranged in the first direction of the substrate; the substrate is a monocrystalline silicon substrate. The diaphragm covers the substrate and the plurality of cavities. The value of the first direction is the result of the substrate; 100 gt; and the crystal orientation deviates within the range of + / -15 degrees. The value of E / (1-v2) of the vibration plate in the interval is small, and the value of E / (1-v2) is at the result of the substrate; 100 gt; and in the direction, the value of E / (1-v2) of the vibration plate is the minimum. Therefore, after the plurality of cavities are arranged along the first direction, the influence of diaphragm thickness deviation, diaphragm quality deviation and mechanical property deviation of the vibrating plate on the uniformity of the piezoelectric element is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and in particular to a piezoelectric element and a preparation method thereof, a piezoelectric device and an electronic device. Background Art

[0002] In recent years, with the development of the semiconductor industry, microelectromechanical systems (MEMS) piezoelectric devices based on piezoelectric elements have been proposed. MEMS piezoelectric devices have the characteristics of small size, light weight, low power consumption, good durability, low price, stable performance, etc. and are widely used in various fields such as industry, biology, and medicine. Moreover, miniaturized, low-voltage driven, and high-speed driven MEMS piezoelectric devices have become the mainstream trend products in the future.

[0003] However, when using the current mainstream preparation process to prepare piezoelectric elements, if miniaturization, low-voltage driving, and high-speed driving are pursued, it will lead to large manufacturing errors of the piezoelectric elements, thereby causing large deviations between the piezoelectric elements. Summary of the invention

[0004] The embodiments of the present application provide a piezoelectric element and a preparation method thereof, a piezoelectric device and an electronic device, which are used to reduce the manufacturing error of the piezoelectric element and improve the uniformity of the piezoelectric element.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] According to a first aspect of an embodiment of the present application, a piezoelectric element is provided for use in MEMS devices such as actuators and sensors. The piezoelectric element includes a substrate, a vibration plate, and a plurality of piezoelectric elements. The substrate has a plurality of cavities penetrating the substrate in a thickness direction, and the plurality of cavities are arranged in sequence along a first direction of the substrate, and the substrate is a single crystal silicon substrate. The vibration plate covers the substrate and the plurality of cavities. The piezoelectric unit includes a first electrode, a piezoelectric layer, and a second electrode stacked on a side of the vibration plate away from the substrate; the projection of the piezoelectric unit on the vibration plate overlaps with the projection of the cavity on the vibration plate; the value of the first direction is within the range of the substrate. <100> The crystal orientation is shifted within the range of ±15°. It should be understood that the first direction can take values ​​within the above range, but the value of the first direction in the same piezoelectric element is the same and fixed, and only one fixed value can be selected in the above range. The value of the first direction in different piezoelectric elements can be different.

[0007] In the piezoelectric element provided in the embodiment of the present application, the arrangement direction of the plurality of cavities in the substrate is <100> The crystal orientation is within the range of ±15°. <100> In the range of crystal orientation deviation ±15°, the vibration plate E / (1-v 2) is smaller, <100> Crystal orientation, E / (1-v 2 ) has the smallest value. Therefore, after arranging the multiple cavities along the above-mentioned direction, the thickness of the vibration plate can be increased when the value of the bending stiffness is fixed. After the thickness of the vibration plate is increased, the proportion of the fluctuation of the thickness of the vibration plate in the overall thickness of the vibration plate during the preparation process will be reduced, which can reduce the influence of the vibration plate film thickness deviation, film quality deviation and mechanical property deviation on the uniformity of the piezoelectric element. It is helpful to reduce the performance deviation and performance fluctuation of the piezoelectric element caused by the vibration plate film thickness deviation, film quality deviation and mechanical property deviation on the basis of realizing miniaturized and high-density piezoelectric elements.

[0008] In a possible implementation, the first direction is E / (1-v 2 ) is the direction with the smallest value; E is the Young's modulus of the vibration plate, and v is the Poisson's ratio of the vibration plate. 2 ) is arranged in the direction with the smallest value, which can minimize the influence of the vibration plate film thickness deviation, film quality deviation and mechanical property deviation on the uniformity of the piezoelectric element.

[0009] In one possible implementation, the cross section of the cavity parallel to the substrate is a strip pattern, and multiple cavities are arranged in a direction parallel to the short side of the strip pattern. By setting the cross section of the cavity to a strip pattern, large bit variables and small spacing can be taken into account while meeting the needs of piezoelectric elements. Taking the application of piezoelectric elements to the inkjet head of a printer as an example, the cavity needs to be large enough to generate sufficient vibration displacement and pressure, so a large bit variable is required. Each cavity is connected to the inkjet port on the outside, and the spacing between the inkjet ports must be small enough to meet the actual printing needs, so a small spacing is required.

[0010] In one possible implementation, the thickness of the vibration plate is 0.5um to 5um. If the vibration plate is too thin, the rigidity of the vibration plate will be insufficient, which will cause the vibration plate to be too soft and unable to provide stable vibration characteristics. If the vibration plate is too thick, the rigidity of the vibration plate will be too high, which will cause the vibration plate to be too stiff and unable to achieve the desired vibration response. By selecting the thickness of the vibration plate within the range of 0.5um to 5um, the rigidity of the vibration plate can be moderate, and it can be used as an etching barrier layer.

[0011] In a possible implementation, the vibration plate is a membrane layer formed of a single crystal material. The displacement change generated by the vibration plate directly causes the change of the cavity volume. In this application, by setting the vibration plate as a membrane layer formed of a single crystal material, the uniformity of the Young's modulus and Poisson's ratio of the vibration plate can be improved, so as to improve the uniformity of the quality of the vibration plate membrane layer.

[0012] In a possible implementation, the single crystal material includes single crystal oxide. The vibration plate made of single crystal oxide has a simple structure.

[0013] In a possible implementation, the crystal orientation of the vibration plate is the same as that of the substrate. The crystal orientation of the vibration plate is determined by the direction of the substrate. If the crystal orientation of the vibration plate and the substrate is the same, then E / (1-v 2 The smaller range of ) is <100> Within the range of crystal orientation deviation of ±15°, the performance deviation and fluctuation of the piezoelectric element are reduced to a great extent.

[0014] In one possible implementation, the substrate is oriented (100) and the flat side of the substrate is <110> or <100> The piezoelectric element of the present application is suitable for a substrate with a (100) orientation.

[0015] In one possible implementation, the substrate is oriented (110) and the flat side of the substrate is <110> , <100> or <111> The piezoelectric element of the present application is also applicable to a substrate with a (110) orientation.

[0016] According to a second aspect of the embodiments of the present application, a piezoelectric device is provided, comprising a driving circuit and a piezoelectric element as described in any one of the first aspects, wherein the driving circuit is electrically connected to the piezoelectric element.

[0017] The piezoelectric device provided in the second aspect of the embodiment of the present application includes the piezoelectric element of the first aspect, and its beneficial effects are the same as those of the piezoelectric element, which will not be repeated here.

[0018] According to a third aspect of the embodiments of the present application, an electronic device is provided, comprising a housing and a piezoelectric device as in the second aspect, wherein the piezoelectric device is disposed in the housing.

[0019] The electronic device provided in the third aspect of the embodiment of the present application includes the piezoelectric element of the first aspect, and its beneficial effects are the same as those of the piezoelectric element, which will not be repeated here.

[0020] According to a fourth aspect of the embodiments of the present application, a method for preparing a piezoelectric element is provided, comprising: providing a substrate; the substrate is a single crystal silicon substrate; forming a vibration plate on one side of the substrate, the vibration plate covering the substrate; forming a plurality of piezoelectric units on a side of the vibration plate away from the substrate; the projection of the piezoelectric unit on the vibration plate overlaps with the projection of the cavity on the vibration plate; the piezoelectric unit comprises a first electrode, a piezoelectric layer and a second electrode stacked on a side of the vibration plate away from the substrate; forming a plurality of cavities penetrating the substrate on the substrate; the plurality of cavities are arranged in sequence along a first direction of the substrate; the value of the first direction is in the range of <100> The crystal orientation deviation is within the range of ±15°.

[0021] The beneficial effects of the electronic device provided in the fourth aspect of the embodiment of the present application are the same as the beneficial effects of the piezoelectric element in the first aspect, and will not be repeated here.

[0022] In a possible implementation, forming a vibration plate on one side of the substrate includes: forming the vibration plate on one side of the substrate using an epitaxial growth process. The crystal orientation of the vibration plate formed using the epitaxial growth process is the same as that of the substrate, and the two are lattice matched.

[0023] In a possible implementation, the thickness of the vibration plate is 0.5 um to 5 um.

[0024] In a possible implementation, the vibration plate is a film layer formed by depositing a single crystal material.

[0025] In a possible implementation, the material of the vibration plate includes single crystal oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the architecture of an electronic device provided in an embodiment of the present application;

[0027] Figure 2A A schematic diagram of the structure of a piezoelectric element according to an embodiment of the present application;

[0028] Figure 2B A schematic diagram of the structure of another piezoelectric element according to an embodiment of the present application;

[0029] Figure 3 A schematic diagram of a preparation process of a piezoelectric element provided in an embodiment of the present application;

[0030] Figure 4-Figure 8 A schematic diagram of a preparation process of a piezoelectric element provided in an embodiment of the present application;

[0031] Fig. 9A A curve diagram of Young's modulus of a vibration plate provided in an embodiment of the present application;

[0032] Fig. 9B A curve diagram of the Poisson's ratio v of a vibration plate provided in an embodiment of the present application;

[0033] Fig. 9C A vibration plate provided in an embodiment of the present application Graph of

[0034] Fig.9D A curve diagram of Young's modulus of another vibration plate provided in an embodiment of the present application;

[0035] Fig.9E A curve diagram of Poisson's ratio v of another vibration plate provided in an embodiment of the present application;

[0036] Fig.9F Another vibration plate provided in the embodiment of the present application Graph of

[0037] Fig.10 A schematic diagram of an arrangement of cavities provided in an embodiment of the present application;

[0038] Fig.11 A top view of a piezoelectric element provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0040] In the following, the terms "second", "first", etc. are used only for convenience of description and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "second", "first", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0041] In addition, in the embodiments of the present application, directional terms such as "up", "down", "left" and "right" may be defined including but not limited to the orientation relative to the schematic placement of the components in the drawings. It should be understood that these directional terms may be relative concepts, which are used for relative description and clarification, and may change accordingly according to changes in the orientation of the components in the drawings.

[0042] In the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. In addition, the term "coupled" can be a direct electrical connection or an indirect electrical connection through an intermediate medium. The term "contact" can be a direct contact or an indirect contact through an intermediate medium.

[0043] In the embodiments of the present application, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B may be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0044] With the progress of science and technology, electronic and mechanical systems are developing towards miniaturization and micro-miniaturization. High-density, multi-functional and intelligent integration of chips has become an important research direction, thus giving birth to micro-electromechanical systems (MEMS) technology characterized by miniaturization, integration and intelligence. Actuators, sensors, micro-optical systems, radio frequency systems, micro-chips, microfluidic devices, three-dimensional integrated circuits and other electromechanical conversion piezoelectric devices based on MEMS technology have been widely used in industry, biology, medicine and other industries.

[0045] The present application embodiment provides an electronic device. Figure 1 As shown, the electronic device 1 may be an electronic product including a piezoelectric device 10 that requires a high driving voltage and a large deformation (displacement), and the piezoelectric device 10 is, for example, a sensor or an actuator. For example, the piezoelectric device 10 includes a MEMS micromirror, a MEMS microphone, a MEMS speaker, a micro pump, an inkjet head, an ultrasonic sensor, a MEMS radio frequency device, etc.

[0046] In some embodiments, the electronic device 1 includes a housing, and the piezoelectric device 10 is disposed in the housing. The electronic device 1 may be, for example, a projector, a radar, a mobile phone, a headset, a radiator, a printer, an ultrasound machine, etc. The embodiment of the present application does not impose any special restrictions on the specific form of the electronic device 1.

[0047] For example, the electronic device 1 is a printer, and the piezoelectric device 10 is applied in the printer as an inkjet head of the printer.

[0048] The present application embodiment provides a piezoelectric device 10, such as Figure 1 As shown, the piezoelectric device 10 includes a piezoelectric element 20 and a driving circuit 30. The driving circuit 30 is used to provide a driving voltage (which can be a DC voltage or an AC voltage) to the piezoelectric element 20, so that an electric field is generated in the piezoelectric element 20. The piezoelectric element 20 converts electrical energy into mechanical energy under the action of the electric field, so that the piezoelectric element 20 generates mechanical displacement or force output.

[0049] It is understandable that the piezoelectric device 10 may also include other devices. For example, the piezoelectric device 10 may also include a processor, which can detect the mechanical displacement or force output by the piezoelectric element 20 and adjust the voltage applied by the drive circuit 30 to achieve the desired movement or force control.

[0050] In recent years, piezoelectric materials such as lead zirconate titanate (Pb(Zr,Ti)O3, PZT) are being widely used in piezoelectric elements 20. By forming such piezoelectric materials in the form of thin films on substrates such as silicon / silicon dioxide and then performing MEMS processing, a small and high-performance piezoelectric element 20 can be realized.

[0051] Figure 2A A schematic diagram of the structure of a piezoelectric element according to an embodiment of the present application.

[0052] The present application embodiment shows a piezoelectric element 20, such as Figure 2A As shown, it includes a substrate 21, a vibration plate 22 and a piezoelectric unit 23. The piezoelectric unit 23 includes a first electrode 231, a piezoelectric layer 232 and a second electrode 233 which are stacked on a side of the vibration plate 22 away from the substrate 21.

[0053] A voltage may be applied to the first electrode 231 and the second electrode 233 , thereby forming an electric field between the first electrode 231 and the second electrode 233 . Under the influence of the electric field, the piezoelectric layer 232 is deformed and the vibration plate 22 vibrates, thereby utilizing the inverse piezoelectric effect to convert electrical energy into mechanical energy.

[0054] The piezoelectric layer 232 is a perovskite oxide thin film containing Pb, Zr, and Ti. The crystal orientation of the piezoelectric layer 232 is <100> or <001> The vibration plate 22 is formed on a substrate 21 made of silicon (Si) by sputtering, thermal film forming, and low pressure chemical vapor deposition (LPCVD). The vibration plate 22 is a stacked structure including a silicon nitride layer 221, a silicon oxide layer 222, and a polysilicon layer 223.

[0055] If the vibration plate 22 is formed by sputtering, heat treatment film forming method, or LPCVD method, the obtained film layer is amorphous, and the Young's modulus of the film layer in the amorphous state is uneven. Moreover, affected by the deposition conditions and cavity conditions, the uniformity of the quality of the produced film layer will also be different. Therefore, it is difficult to maintain a constant Young's modulus and a constant Poisson's ratio during manufacturing. When a miniaturized and high-density piezoelectric element 20 is required, the vibration plate 22 needs to be thinner, and the uniformity of the film layer quality is even more difficult to ensure.

[0056] Figure 2B A schematic diagram of the structure of a piezoelectric element according to an embodiment of the present application.

[0057] The present application embodiment shows a piezoelectric element 20, such as Figure 2B As shown, it includes a substrate 21, a vibration plate 22 and a piezoelectric unit 23. The piezoelectric unit 23 includes a first electrode 231, a piezoelectric layer 232 and a second electrode 233 which are stacked on a side of the vibration plate 22 away from the substrate 21.

[0058] The substrate 21 is a silicon on insulator (SOI) substrate, and the SOI substrate includes a stacked base layer 211, an insulating layer 212, and a device silicon layer 213. The substrate 21 includes a cavity 214 that penetrates the base layer 211, and the cavity 214 provides a vibration space for the device silicon layer 213 used for the vibration plate. The insulating layer 212 is between the base layer 211 and the device silicon layer 213, and is used to achieve electrical isolation between the substrate and the device silicon layer. The insulating layer 212 can be a silicon oxide layer obtained by thermal oxygen growth or chemical vapor deposition (CVD). The device silicon layer 213 is reused as the vibration plate 22 of the piezoelectric element 20, and the thickness of the device silicon layer 213 can be flexibly set according to the requirements of different actuators for the vibration plate.

[0059] The process of manufacturing the piezoelectric element 20 is as follows: first, an SOI substrate is formed. Then, a piezoelectric unit 23 is formed on the device silicon layer 213 of the SOI substrate. Finally, the base layer 211 is etched on a side of the base layer 211 away from the insulating layer 212 to form a cavity 214 penetrating the base layer 211, and the insulating layer 212 is used as an etching stop layer.

[0060] The vibration plate 22 is made of a single crystal silicon-based material, and the Young's modulus of the vibration plate 22 varies according to the direction within the crystal plane. By aligning the short side direction of the vibration plate 22 in a specific direction, the Young's modulus of the short side direction of the vibration plate 22 is made smaller than the Young's modulus of the long side direction, thereby making the vibration plate 22 easier to deform, thereby enhancing the displacement characteristics of the piezoelectric element.

[0061] The active layer substrate of the vibration plate 22 is formed of a single crystal silicon-based material, which can solve the problem of Figure 2A The problem of uneven film quality of the vibration plate 22. However, an SOI substrate needs to be used in the piezoelectric element 20, and the SOI substrate is usually a pre-formed substrate. In order to adapt to the requirements of different types of piezoelectric elements 20 for the thickness of the vibration plate 22, it is generally necessary to thin the device silicon layer 213 through a grinding process so that the device silicon layer 213 has a preset thickness. However, the grinding process will cause a large deviation in the film thickness of the device silicon layer 213, and the film thickness error of the grinding process is generally ±0.5um. This error will directly lead to an error in the piezoelectric element 20. Although it is proposed to increase the sensitivity of the thickness of the vibration plate 22 to the vibration displacement by changing the Young's modulus of the vibration plate 22 according to the direction within the crystal plane, and to reduce the relative change by making the vibration plate 22 itself thicker, this still cannot avoid the thickness deviation and uniformity problems caused by the grinding process.

[0062] Based on this, an embodiment of the present application further provides a piezoelectric element 20 and a method for manufacturing the same, which are used to reduce the manufacturing error of the piezoelectric element 20 and improve the uniformity of the piezoelectric element 20 .

[0063] Figure 3 A schematic diagram of a preparation process of a piezoelectric element provided in an embodiment of the present application, Figure 4-Figure 8 A schematic diagram of a preparation process of a piezoelectric element provided in an embodiment of the present application.

[0064] The present application also provides a method for preparing a piezoelectric element 20. Figure 3 As shown, the preparation method comprises:

[0065] S10, such as Figure 4 As shown, a substrate 21 is provided.

[0066] The piezoelectric element 20 provided in the embodiment of the present application includes a substrate 21 , and the substrate 21 is a single crystal silicon substrate.

[0067] The embodiment of the present application does not limit the thickness of the substrate 21. For example, the thickness of the substrate 21 may be a standard thickness of 300 μm to 800 μm.

[0068] The embodiment of the present application does not limit the diameter of the substrate 21 , and the substrate 21 may be a large-sized substrate 21 such as 8 inches or 12 inches, or a small-sized substrate 21 .

[0069] In addition, the embodiment of the present application does not limit the orientation of the substrate 21, and the single crystal silicon substrate can be oriented in (100) or (110).

[0070] Compared with SOI substrates, the manufacturing process of single-crystal silicon substrates is simple and the cost is low. At the same time, single-crystal silicon substrates have good mechanical properties, such as high mechanical strength, high linearity, low creep mechanical properties, and low internal stress, so they can improve the output displacement, force or angle of the actuator, as well as better linearity, consistency and reliability.

[0071] S20, such as Figure 5 As shown, a vibration plate 22 is formed on one side of a substrate 21.

[0072] In some embodiments, the vibration plate 22 is formed on one side of the substrate 21 by an epitaxial growth process, and the orientation of the vibration plate 22 is the same as the orientation of the substrate 21. For example, the vibration plate 22 is formed by a metal organic chemical vapor deposition (MOCVD) process, an electron beam evaporation process, a magnetron sputtering process, or other applicable processes, and the orientation of the vibration plate 22 can be (100) or (110).

[0073] The piezoelectric element 20 provided in the embodiment of the present application includes a vibration plate 22 . The vibration plate 22 covers one side of a substrate 21 . The material of the vibration plate 22 is different from that of the substrate 21 .

[0074] In some embodiments, the vibration plate 22 is a film layer formed of a single crystal material.

[0075] In some embodiments, the material of the vibration plate 22 includes a single crystal oxide. For example, the material of the vibration plate 22 includes a perovskite metal oxide. For example, the material of the vibration plate 22 includes one or more of the following combinations: zirconium oxide (ZrO2), yttrium stabilized zirconium oxide (YSZ), hafnium oxide (HfO2), and hafnium zirconium oxide (HfZrO2).

[0076] The displacement change produced by the vibration plate 22 directly causes the change of the volume of the cavity 214. The present application can improve the uniformity of the Young's modulus and Poisson's ratio of the vibration plate 22 by setting the vibration plate 22 as a film layer formed by a single crystal material, so as to improve the uniformity of the quality of the film layer of the vibration plate 22.

[0077] Since the stiffness of the vibration plate 22 has an important influence on its natural frequency and resonant frequency, a higher stiffness can make the natural frequency of the vibration plate 22 higher, thereby improving its frequency stability. In addition, the sensitivity of the vibration plate 22 is an important indicator affecting the performance of the piezoelectric element 20, and a higher stiffness can make the vibration plate 22 more sensitive to external excitation, that is, more likely to produce displacement or response, thereby improving the performance of the piezoelectric element 20.

[0078] Based on this, in some embodiments, the thickness of the vibration plate 22 is 0.5um-5um, so that the vibration plate 22 has a suitable stiffness. For example, the thickness of the vibration plate 22 is 1um, 1.5um, 2um, 2.5um, 3um, 3.5um, 4um, 4.5um, etc.

[0079] If the vibration plate 22 is too thin, the rigidity of the vibration plate 22 will be insufficient, and the vibration plate 22 will be too soft and unable to provide stable vibration characteristics. If the vibration plate 22 is too thick, the rigidity of the vibration plate 22 will be too high, and the vibration plate 22 will be too stiff and unable to achieve the required vibration response. By selecting the thickness of the vibration plate 22 within the range of 0.5um to 5um, the rigidity of the vibration plate 22 can be moderate, and it can be used as an etching barrier layer.

[0080] S30, such as Figure 6 As shown, a plurality of piezoelectric units 23 are formed on a side of the vibration plate 22 away from the substrate 21 .

[0081] The piezoelectric element 20 provided in the embodiment of the present application further includes a piezoelectric unit 23 , which includes a first electrode 231 , a piezoelectric layer 232 , and a second electrode 233 stacked on a side of the vibration plate 22 away from the substrate 21 .

[0082] In some embodiments, step S30 includes:

[0083] S31 , forming a first electrode film 231 ′ on a side of the vibration plate 22 away from the substrate 21 .

[0084] Because, when the piezoelectric element 20 is applied to the piezoelectric device 10, the miniaturization, low voltage driving and high speed driving of the piezoelectric element 20 are pursued. The higher the piezoelectric constant of the piezoelectric element 20, the more effectively it can be driven relative to the input voltage, and the larger the capacitance of the piezoelectric element 20, the greater the power consumption during driving and the heat generation of the element itself. Therefore, the piezoelectric element 20 applied to the piezoelectric device 10 needs to have a higher piezoelectric constant and a lower dielectric constant. The crystal orientation of the piezoelectric unit 23 has a great influence on the piezoelectric properties of the piezoelectric element 20, especially the piezoelectric properties such as conversion efficiency, dielectric constant, and dielectric loss. Therefore, the film forming state of the first electrode film 231' is also more important.

[0085] In some embodiments, the first electrode film 231' can be formed on the side of the vibration plate 22 away from the substrate 21 by a sputtering process or an electron evaporation process. The material of the first electrode film 231' can be a polysilicon material or a metal material, and the metal material can include one or more combinations of the following: platinum (Pt), gold (Au), copper (Cu), and aluminum (Al).

[0086] In some embodiments, the orientation of the first electrode film 231 ′ is the same as the orientation of the vibration plate 22. For example, the first electrode film 231 ′ is (100) or (110). The orientation of the first electrode film 231 ′ is consistent with the orientation of the vibration plate 22, so that the piezoelectric layer 232 formed subsequently has good piezoelectric properties.

[0087] It can be understood that the first electrode film 231' being oriented (100) here means that more than half of the crystals in the first electrode film 231' are oriented (100), for example, 90% of the crystals in the first electrode film 231' are oriented (100), and a small amount of other orientations may also exist in the first electrode film 231', for example, there may also be crystals oriented (001). Similarly, the first electrode film 231' being oriented (110) means that more than half of the crystals in the first electrode film 231' are oriented (110), for example, 90% of the crystals in the first electrode film 231' are oriented (110), and a small amount of other orientations may also exist in the first electrode film 231'.

[0088] In some embodiments, the thickness of the first electrode film 231 ′ is 100 nm to 200 nm. For example, the thickness of the first electrode film 231 ′ is 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm.

[0089] In some embodiments, before performing the subsequent step S32 , the preparation method further includes: forming a buffer layer on the first electrode film 231 ′ by a sputtering process, a chemical solution deposition process or other suitable processes.

[0090] The orientation of the buffer layer is the same as that of the first electrode film 231', so as to ensure that the piezoelectric layer 232 formed subsequently has good piezoelectric properties. The buffer layer can serve as an adhesion layer between the first electrode film 231' and the piezoelectric film 232' to prevent the piezoelectric film 232' from peeling off from the first electrode film 231'. At the same time, the buffer layer can also serve as a barrier layer to prevent the material for forming the piezoelectric film 232' subsequently from diffusing into the first electrode film 231'.

[0091] S32 , forming a piezoelectric film 232 ′ on a side of the first electrode film 231 ′ away from the vibration plate 22 .

[0092] The piezoelectric film 232' includes, for example, one or more perovskite structures such as strontium ruthenate (Sr2RuO4, SRO), lead lanthanum titanate ((Pb, La)TiO3, PLT) and disodium lanthanum oxide tetrahydrate (LaNiO3, LNO).

[0093] In some embodiments, step S32 includes:

[0094] S321 : depositing a precursor solution of the piezoelectric film 232 ′ on the first electrode film 231 ′.

[0095] For example, the precursor solution of the piezoelectric film 232' is formed by chemical solution deposition, sputtering, spin coating or other suitable processes. For example, the sol precursor solution is coated on the substrate 21 at a rotation speed of 2000 rpm to 3000 rpm by a spin coater, and the precursor solution of the piezoelectric film 232' has a desired thickness by controlling the rotation speed, time, liquid amount, etc. The material in the precursor solution of the piezoelectric film 232' may include one or more perovskite structures such as SRO, PLT and LNO.

[0096] S322: Drying the precursor solution to form a thin film layer.

[0097] For example, the precursor solution is heated at about 100° C. to 150° C. for about 10 minutes to 30 minutes using a hot plate or an electric furnace to burn and remove organic matter and water present in the precursor solution.

[0098] S323: Pre-sintering the thin film layer to form an inorganic film layer.

[0099] For example, the residual organic matter is thermally decomposed by heating at about 200° C. to 450° C. for about 10 to 30 minutes using a hot plate or an electric furnace.

[0100] S324: calcining the inorganic film layer to form a single crystal seed layer.

[0101] For example, rapid thermal annealing (RTA) or other suitable processes are used to heat at about 600°C to 700°C for about 5 minutes to 30 minutes for calcination until the desired film thickness of the perovskite single crystal is reached. During calcination, specific gases such as oxygen are introduced and pressure sintering is performed to obtain a denser single crystal seed layer.

[0102] Repeat the above steps S321 to S324 until a piezoelectric film 232' having a desired thickness is formed. For example, the thickness of the piezoelectric film 232' is 1 um to 5 um.

[0103] In most cases, PZT materials are crystals composed of lead (Pb), zirconium (Zr), titanium (Ti), and oxygen (O). PZT with a perovskite structure exhibits good piezoelectric effects. The ideal perovskite structure is a cubic lattice, which is composed of metals such as Pb configured at the vertices (A position) of the cubic crystal, Zr and Ti configured at the body center (B position), and O configured at the face centers (C position) of the cubic crystal, thereby forming an ABO3 crystal. Among them, Zr and Ti occupy the same position, but the ratio is adjustable. Crystals with a perovskite structure also include tetragonal crystals, orthorhombic crystals, rhombohedral symmetry, etc. that are deformed from cubic crystals. Moreover, the orientation of the crystal has a great influence on piezoelectric properties, especially piezoelectric properties such as electromechanical conversion efficiency, dielectric constant, and dielectric loss. Therefore, in order to control the orientation or crystallinity, it becomes important to control the film forming state of the first electrode film 231′ and the piezoelectric film 232′ during the film forming process.

[0104] In the embodiment of the present application, in order to make the PZT material in the piezoelectric film 232' have a perovskite-type single-phase structure, the crystal structure of the material in the first electrode film 231' is similar to the above-mentioned perovskite-type single-phase structure through the above-mentioned manufacturing process, and the orientation of the piezoelectric film 232' using the PZT material also replicates the orientation of the first electrode film 231', so that the PZT material in the piezoelectric film 232' has a perovskite-type single-phase structure, that is, the piezoelectric film 232' is also (100) or (110) oriented, and the piezoelectric film 232' and the first electrode film 231' are lattice-matched, so that the piezoelectric film 232' with this orientation has good piezoelectric properties, that is, it has a higher piezoelectric constant and a lower dielectric constant. Using the inverse piezoelectric effect, under the action of the electric field, the piezoelectric film 232' is deformed, so that the electrical energy can be converted into mechanical energy to realize various functions of the actuator.

[0105] In some embodiments, before performing the subsequent step S33 , the preparation method further includes: forming a buffer layer on the piezoelectric film 232 ′ by a sputtering process, a chemical solution deposition process or other suitable processes.

[0106] The buffer layer can be used as an adhesion layer between the piezoelectric film 232' and the second electrode film 233' to prevent the piezoelectric film 232' and the second electrode film 233' from peeling off. At the same time, the buffer layer can also be used as a barrier layer to prevent the material forming the piezoelectric film 232' from diffusing into the second electrode film 233'.

[0107] S33 , forming a second electrode film 233 ′ on a side of the piezoelectric film 232 ′ away from the first electrode film 231 ′.

[0108] For example, the second electrode film 233' is formed on the piezoelectric film 232' by a sputtering process or an electron evaporation process. The material of the second electrode film 233' can be a polysilicon material, a metal material or an oxide material. The material of the second electrode film 233' can include one or more of the following combinations: Pt, Au, Cu, Al, iridium dioxide (IrO2).

[0109] S34 , patterning the second electrode film 233 ′, the piezoelectric film 232 ′ and the first electrode film 231 ′ to form a patterned second electrode 233 , a piezoelectric layer 232 and a first electrode 231 to form a piezoelectric unit 23 .

[0110] For example, the second electrode film 233', the piezoelectric film 232' and the first electrode film 231' are patterned by a patterning process, and the patterning process includes a photolithography process and an etching process. The photolithography process includes, for example, photoresist coating (such as spin coating), soft baking, mask alignment, exposure, post-exposure baking, developing photoresist, rinsing and drying (such as hard baking). The etching process includes, for example, a dry etching process or a wet etching process.

[0111] It should be understood that multiple of the second electrode film 233', the piezoelectric film 232' and the first electrode film 231' can be patterned in the same patterning process, or the second electrode film 233', the piezoelectric film 232' and the first electrode film 231' can be patterned separately, which is not limited in the embodiments of the present application. Depending on the patterning process, the dimensions of the second electrode 233, the piezoelectric layer 232 and the first electrode 231 along the direction parallel to the substrate 21 will also be different. Figure 6 The example in which the second electrode 233 , the piezoelectric layer 232 , and the first electrode 231 have the same dimensions along a direction parallel to the substrate 21 is used for illustration.

[0112] like Figure 6As shown, the piezoelectric element 20 provided in the embodiment of the present application includes a piezoelectric unit 23, and the piezoelectric unit 23 includes a first electrode 231, a piezoelectric layer 232, and a second electrode 233 that are sequentially arranged along the side of the vibration plate 22 away from the substrate 21. Of course, the piezoelectric unit 23 can also add other film layers on the basis of the first electrode 231, the piezoelectric layer 232, and the second electrode 233. For example, a buffer layer can be provided between the first electrode 231 and the piezoelectric layer 232, and a buffer layer can be provided between the piezoelectric layer 232 and the second electrode 233. The structure of the piezoelectric unit 23 illustrated in the embodiment of the present application is only an illustration and is not limited in any way.

[0113] In some embodiments, Figure 7 As shown, the plurality of first electrodes 231 of the plurality of piezoelectric units 23 included in the piezoelectric element 20 are coupled to each other. Then, the patterned shape when the first electrode film 231' is patterned is different from the patterned shape when the second electrode film 233' and the piezoelectric film 232' are patterned. For example, the plurality of first electrodes 231 of the plurality of piezoelectric units 23 are connected into a sheet-like structure.

[0114] In some embodiments, the piezoelectric element 20 further includes a pad and a wiring coupled to the first electrode 231 and the second electrode 233. For example, the pad and the wiring are both arranged in the same layer as the second electrode 233 and formed synchronously. Alternatively, for example, the pad and the wiring are arranged in different layers from the second electrode 233, and the pad and the wiring are located on the side of the second electrode 233 away from the substrate 21. For example, the pad and the wiring are arranged in the same layer, and there is an insulating layer between the layer where the pad and the wiring are located and the layer where the second electrode 233 is located. The pad and the wiring can also be arranged in different layers, and there can also be an insulating layer between the pad and the wiring.

[0115] S40, such as Figure 8 As shown, a plurality of cavities 214 penetrating the substrate 21 are formed on the substrate 21 .

[0116] For example, the substrate 21 is etched from the side of the substrate 21 away from the vibration plate 22 by photolithography and deep silicon etching to form a cavity 214 penetrating the substrate 21 on the substrate 21. For example, the cavity 214 is formed by Bosch process.

[0117] In the embodiment of the present application, the substrate 21 is etched by a dry etching process, and the vibration plate 22 serves as an etching stop layer during the etching process. That is, when the etching depth reaches the vibration plate 22, since the vibration plate 22 reacts slowly or does not react with the etching medium, the vibration plate 22 can effectively prevent the etching from continuing, thereby controlling the etching depth and forming a cavity 214 that penetrates the substrate 21. The dry etching process uses an etching gas as an etching medium, and the etching gas includes, for example, one or more of the following combinations: carbon tetrafluoride (CF4), argon (Ar), nitrogen trifluoride (NF3), chlorine (Cl2), helium (He), hydrogen bromide (HBr), oxygen (O2), nitrogen (N2), fluoromethane (CH3F), methane (CH4), and difluoromethane (CH2F2).

[0118] like Figure 8 As shown, in the piezoelectric element 20 provided in the embodiment of the present application, the substrate 21 includes a cavity 214, the vibration plate 22 covers the cavity 214, and the projection of the piezoelectric unit 23 on the vibration plate 22 overlaps with the projection of the cavity 214 on the vibration plate 22. Then, when the substrate 21 includes a plurality of cavities 214, and the piezoelectric element 20 includes a plurality of piezoelectric units 23, the plurality of piezoelectric units 23 and the plurality of cavities 214 are arranged in a one-to-one correspondence, and the projections of the correspondingly arranged piezoelectric units 23 and cavities 214 on the vibration plate 22 overlap. Figure 8 Only one cavity 214 and one piezoelectric unit 23 are shown schematically.

[0119] Next, the arrangement of the cavity 214 and the piezoelectric unit 23 will be described.

[0120] The bending stiffness D of the vibration plate 22 is calculated as shown in the following formula. The bending stiffness D is proportional to the cube of the film thickness h of the vibration plate 22 and the Young's modulus E, and is proportional to (1-v 2 ) is inversely proportional to.

[0121]

[0122] It can be seen from the above formula that when the film thickness h of the vibration plate 22 is constant, The smaller the value of , the lower the bending rigidity D, and the greater the displacement of the piezoelectric element 20 .

[0123] Fig. 9A A graph showing the Young's modulus of a vibration plate provided in an embodiment of the present application. Fig. 9B A curve diagram of the Poisson's ratio of a vibration plate provided in an embodiment of the present application, Fig. 9C A vibration plate provided in an embodiment of the present application Graph of the curve.

[0124] The substrate 21 is oriented (100) and the flat side of the substrate 21 is <110> direction as an example. Fig. 9A As shown, the vibration plate 22 is at an angle of 45° with the flat edge. <100> The Young's modulus E in the direction is the smallest. Fig. 9B As shown, the vibration plate 22 is at an angle of 45° with the flat edge. <100> The Poisson's ratio v is the largest in the direction. Therefore, Fig. 9C As shown, the vibration plate 22 is <100> Directional The value of is the smallest, and the vibration plate 22 is <100> Directional The bending stiffness D of the cavity 214 and the piezoelectric unit 23 is the lowest. <100> When the vibration plate 22 is arranged in the same direction, the deformation can be generated most effectively and the vibration displacement can be increased. From the above description, it can be seen that the orientation of the vibration plate 22 is the same as the orientation of the substrate 21. Then, the vibration plate 22 is at an angle of 45° with the flat edge. <100> Directional The value of is the smallest.

[0125] The substrate 21 is oriented (100) and the flat side of the substrate 21 is <100> direction as an example, the vibration plate 22 is at an angle of 90° with the flat edge. <100> The Young's modulus E in the direction is the smallest, the Poisson's ratio v is the largest, The value of is the smallest.

[0126] Fig.9D A graph showing the Young's modulus of a vibration plate provided in an embodiment of the present application. Fig.9E A curve diagram of the Poisson's ratio of a vibration plate provided in an embodiment of the present application, Fig.9F A vibration plate provided in an embodiment of the present application Graph of the curve.

[0127] The substrate 21 is oriented (110) and the flat edge of the substrate 21 is <110> direction as an example. Fig.9D As shown, the vibration plate 22 is at an angle of 90° with the flat edge. <100> The Young's modulus E in the direction is the smallest. Fig.9E As shown, the vibration plate 22 is at an angle of 90° with the flat edge. <100> The Poisson's ratio v is the largest in the direction. Therefore, Fig.9F As shown, the vibration plate 22 is <100> Directional The value of is the smallest, and the vibration plate 22 is <100> Directional The bending stiffness D of the cavity 214 and the piezoelectric unit 23 is the lowest. <100> When the vibration plate 22 is arranged in the same direction, the deformation can be generated most effectively and the vibration displacement can be increased. From the above description, it can be seen that the orientation of the vibration plate 22 is the same as the orientation of the substrate 21. Then, the vibration plate 22 is at an angle of 90° with the flat edge. <100> Directional The value of is the smallest.

[0128] The substrate 21 is oriented (110) and the flat edge of the substrate 21 is <110> direction as an example, the vibration plate 22 is at an angle of 90° with the flat edge. <100> The Young's modulus E in the direction is the smallest, the Poisson's ratio v is the largest, The value of is the smallest.

[0129] Fig.10 A schematic diagram of a cavity arrangement provided in an embodiment of the present application.

[0130] Based on this, in some embodiments, such as Fig.10 As shown, the plurality of cavities 214 in the substrate 21 are sequentially arranged along a first direction of the substrate 21, and the value of the first direction is <100> The crystal orientation deviation is within the range of ±15°.

[0131] It should be understood that the first direction can take values ​​within the above range, but the value of the first direction in the same piezoelectric element is the same and fixed, and only one fixed value can be selected in the above range. The values ​​of the first direction in different piezoelectric elements can be different.

[0132] In the embodiment of the present application, the substrate 21 may be oriented in a (100) direction, with a flat edge. <110> or <100> The substrate 21 may also be (110) oriented with flat edges. <110> , <100> or <111> The present application embodiment does not limit this.

[0133] For example, the substrate 21 is oriented (100) and the flat side of the substrate 21 is <110> direction, the value of the first direction is at the substrate 21 <100> If the crystal orientation is shifted within the range of ±15°, it means that the first direction is within the range of ±15° shifted from the angle of 45° between the substrate 21 and the flat side. That is, the first direction is the orientation corresponding to the angle of 30° to 60° between the substrate 21 and the flat side.

[0134] Alternatively, for example, the substrate 21 is oriented (100) and the flat side of the substrate 21 is <100> direction, the value of the first direction is at the substrate 21 <100> The crystal orientation shifts within the range of ±15°, which means that the first direction is within the range of ±15° shifted from the angle of 90° between the substrate 21 and the flat side. That is, the first direction is the orientation corresponding to the angle of 75° to 105° between the substrate 21 and the flat side.

[0135] Alternatively, for example, the substrate 21 is oriented (110) and the flat side of the substrate 21 is <110> direction, the value of the first direction is at the substrate 21 <100> The crystal orientation shifts within the range of ±15°, which means that the first direction is within the range of ±15° shifted from the angle of 90° between the substrate 21 and the flat side. That is, the first direction is the orientation corresponding to the angle of 30° to 60° between the substrate 21 and the flat side.

[0136] Alternatively, for example, the substrate 21 is oriented (110) and the flat side of the substrate 21 is <100> direction, the value of the first direction is at the substrate 21 <100> The crystal orientation shifts within the range of ±15°, which means that the first direction is within the range of ±15° shifted from the angle of 90° between the substrate 21 and the flat side. That is, the first direction is the orientation corresponding to the angle of 30° to 60° between the substrate 21 and the flat side.

[0137] Alternatively, for example, the substrate 21 is oriented (110) and the flat side of the substrate 21 is <111> direction, the value of the first direction is at the substrate 21 <100> The crystal orientation deviation is within the range of ±15°.

[0138] In some embodiments, Fig.10 As shown, the cross section of the cavity 214 parallel to the substrate 21 (or understood as the top view of the cavity 214) is a strip pattern, and multiple cavities 214 are arranged along a direction parallel to the short side of the strip pattern. Then, the short side direction of the cavity 214 is parallel to the first direction.

[0139] The cross-sectional shape of the cavity 214 is a strip, for example, the cross-sectional shape of the cavity 214 is a right-angled rectangle, a chamfered rectangle, an ellipse, a diamond, a triangle, a trapezoid, or an irregular strip shape.

[0140] By setting the cross section of the cavity 214 to a strip pattern, large position variables and small spacing can be taken into account while meeting the requirements of the piezoelectric element 20. Taking the application of the piezoelectric element 20 to the inkjet head of a printer as an example, the cavity 214 needs to be large enough to generate sufficient vibration displacement and pressure, so a large position variable is required. Each cavity 214 is connected to the inkjet port on the outside, and the spacing between the inkjet ports must be small enough to meet the actual printing requirements, so a small spacing is required.

[0141] It should be understood that the substrate 21 is a face-centered cubic lattice, and therefore, when the cross-sectional shape of the cavity 214 is a rectangle, the long side direction of the cavity 214 is also parallel to the first direction. <100> The crystal direction is 45° with the flat edge, so the long side direction is also <100> Crystal direction, the direction with an angle of 45° to the flat edge.

[0142] In some embodiments, the first direction is the direction of the vibration plate 22. The direction in which the value of is minimum.

[0143] For example, the first direction is <100> Crystal direction, the direction with an angle of 45° to the flat edge.

[0144] Fig.11 A top view of a piezoelectric element provided in an embodiment of the present application.

[0145] like Fig.11 As shown, the piezoelectric element 20 includes a plurality of piezoelectric units 23 and a plurality of cavities 214 . The plurality of cavities 214 are arranged along a first direction, and the plurality of piezoelectric units 23 are also arranged along the first direction. The projection of the piezoelectric unit 23 on the vibration plate 22 overlaps with the projection of the cavity 214 on the vibration plate 22 .

[0146] In the piezoelectric element 20 provided in the embodiment of the present application, the arrangement direction of the plurality of cavities 214 in the substrate 21 is <100> The crystal orientation is within the range of ±15°. <100> In the range of crystal orientation deviation ±15°, the vibration plate 22 The value of is small, in the substrate 21 <100> Crystal orientation, vibration plate 22 The value of is the smallest. Therefore, after arranging the multiple cavities 214 along the above-mentioned direction, the thickness of the vibration plate 22 can be increased when the value of the bending stiffness D is fixed. After the thickness of the vibration plate 22 is increased, the proportion of the fluctuation of the thickness of the vibration plate 22 in the overall thickness of the vibration plate 22 during the preparation process will be reduced, and the influence of the film thickness deviation, film quality deviation and mechanical property deviation of the vibration plate on the uniformity can be reduced. It is helpful to reduce the performance deviation and performance fluctuation of the piezoelectric element 20 caused by the film thickness deviation, film quality deviation and mechanical property deviation of the vibration plate 22 on the basis of realizing a miniaturized and high-density piezoelectric element 20, and can be applicable to piezoelectric devices 10 with large displacement and small displacement deviation. For example, Figure 2B In the piezoelectric element 20 shown, the thickness fluctuation of the vibration plate 22 is generally about ±20%. Fig.11 In the piezoelectric element shown, the thickness fluctuation of the vibration plate 22 can be controlled within ±5% to ±10%, which can significantly reduce the performance deviation and performance fluctuation of the piezoelectric element 20.

[0147] In addition, the vibration plate 22 formed by the epitaxial process has a crystal direction determined by the direction of the substrate 21. Therefore, it will also appear in different directions on the plane. The distribution of the cavity 214 is different. The piezoelectric element 20 is arranged in a direction with a smaller value, so as to reduce the performance deviation and performance fluctuation of the piezoelectric element 20.

[0148] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A piezoelectric element, characterized in that: include: A substrate having a plurality of cavities penetrating the substrate along a thickness direction, wherein the plurality of cavities are sequentially arranged along a first direction of the substrate; the substrate is a single crystal silicon substrate; a vibration plate covering the substrate and the plurality of cavities; A plurality of piezoelectric units, each of which includes a first electrode, a piezoelectric layer, and a second electrode stacked on a side of the vibration plate away from the substrate; The projection of the piezoelectric unit on the vibration plate overlaps with the projection of the cavity on the vibration plate; The value of the first direction is <100> The crystal orientation deviation is within the range of ±15°.

2. The piezoelectric element according to claim 1, wherein The first direction is E / (1-v 2 ) takes the smallest value; E is the Young's modulus of the vibration plate, and v is the Poisson's ratio of the vibration plate.

3. The piezoelectric element according to claim 1 or 2, characterized in that: The cross section of the cavity parallel to the substrate is a stripe pattern, and the plurality of cavities are arranged along a direction parallel to a short side of the stripe pattern.

4. The piezoelectric element according to any one of claims 1 to 3, characterized in that: The thickness of the vibration plate is 0.5um to 5um.

5. The piezoelectric element according to any one of claims 1 to 3, characterized in that: The vibration plate is a film layer formed of a single crystal material.

6. The piezoelectric element according to any one of claims 1 to 5, characterized in that: The single crystal material includes a single crystal oxide.

7. The piezoelectric element according to any one of claims 1 to 6, characterized in that: The substrate has a (100) orientation and a flat edge. <110> or <100> direction.

8. The piezoelectric element according to any one of claims 1 to 7, characterized in that: The substrate has a (110) orientation and a flat edge. <110> , <100> or <111> direction.

9. A piezoelectric device, characterized in that: The piezoelectric element comprises a driving circuit and the piezoelectric element as claimed in any one of claims 1 to 8, wherein the driving circuit is electrically connected to the piezoelectric element.

10. An electronic device, characterized in that: The invention comprises a housing and the piezoelectric device according to claim 9, wherein the piezoelectric device is arranged in the housing.

11. A method for preparing a piezoelectric element, characterized in that: include: providing a substrate; The substrate is a single crystal silicon substrate; A vibration plate is formed on one side of the substrate, wherein the vibration plate covers the substrate; A plurality of piezoelectric units are formed on the side of the vibration plate away from the substrate; the projection of the piezoelectric unit on the vibration plate overlaps with the projection of the cavity on the vibration plate; the piezoelectric unit comprises a first electrode, a piezoelectric layer and a second electrode stacked on the side of the vibration plate away from the substrate; A plurality of cavities penetrating the substrate are formed on the substrate; the plurality of cavities are arranged in sequence along a first direction of the substrate; and the value of the first direction is <100> The crystal orientation deviation is within the range of ±15°.

12. The preparation method according to claim 11, characterized in that: A vibration plate is formed on one side of the substrate, comprising: The vibration plate is formed on one side of the substrate by using an epitaxial growth process.

13. The preparation method according to claim 11 or 12, characterized in that: The thickness of the vibration plate is 0.5um to 5um.

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