Piezoelectric MEMS transducer and electronic device

Abstract

The invention discloses a piezoelectric MEMS transducer and electronic equipment, and relates to the technical field of MEMS. The piezoelectric MEMS transducer comprises a substrate and a piezoelectric layer formed on the substrate, a cavity is further formed in the substrate, a bottom electrode is arranged on the first surface of the piezoelectric layer, and a first differential electrode and a second differential electrode are arranged on the second surface of the piezoelectric layer; the first differential electrodes and the second differential electrodes are alternately distributed on the second surface of the piezoelectric layer in the first direction, and the bottom electrodes are opposite to the first differential electrodes and the second differential electrodes; the piezoelectric layer is a single-crystal lithium niobate film or a single-crystal lithium tantalate film, the first direction serves as the x-axis positive direction of a right-handed coordinate system, the piezoelectric layer has crystal orientation of a target Euler angle, and the square value of the piezoelectric coupling coefficient of the piezoelectric layer in the first direction is larger than or equal to 1.52%. According to the piezoelectric MEMS transducer, the electromechanical coupling coefficient of the piezoelectric MEMS transducer can be improved.

Description

Technical Field

[0001] The present application relates to the field of MEMS technology, and in particular to a piezoelectric MEMS transducer and an electronic device. Background Art

[0002] Piezoelectric MEMS transducers have the advantages of high performance, small size and low cost, including piezoelectric MEMS microphones, piezoelectric MEMS ultrasonic transducers, piezoelectric MEMS speakers, etc. In general, the higher the electromechanical coupling coefficient of the piezoelectric MEMS transducer, the better the performance, such as the higher the signal-to-noise ratio of the piezoelectric MEMS microphone, the higher the sensitivity of the piezoelectric MEMS ultrasonic transducer, and the greater the output sound pressure of the piezoelectric MEMS speaker.

[0003] like Figure 1A and Figure 1B As shown, a conventional piezoelectric MEMS transducer includes a cavity structure and a diaphragm placed on the cavity, wherein the diaphragm includes a piezoelectric film 100, a bottom electrode 103 (grounded) on the lower surface of the piezoelectric film, and differential electrodes 101 and 102 on the upper surface of the piezoelectric film 100. The edge of the diaphragm, i.e., the boundary 202 of the cavity, is a fixed support boundary. When the piezoelectric film is AlN or PZT, since they have an isotropic piezoelectric coupling coefficient K in the film plane, 31 At this time, the differential electrode distribution direction of the transducer is consistent with the strain distribution direction, both along the radial direction of the annular electrode; the differential electrode distribution direction and the piezoelectric coupling coefficient k 31 The maximum values ​​of are in the same direction, all along the radial direction of the annular electrode.

[0004] However, when the piezoelectric film is single crystal lithium niobate LN or single crystal lithium tantalate LT, they have anisotropic piezoelectric coupling coefficient K 31 At this time, although the differential electrode distribution direction of the transducer is consistent with the strain distribution direction, both are along the radial direction of the annular electrode; however, since the differential electrode distribution direction is along the radial direction of the annular electrode, the piezoelectric coupling coefficient K 31 The maximum direction of is a fixed direction, which leads to a decrease in the electromechanical coupling coefficient of the transducer.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0006] In order to solve at least one of the above problems existing in the prior art, an embodiment of the present application provides a piezoelectric MEMS transducer and an electronic device.

[0007] According to a first aspect of an embodiment of the present application, the present application provides a piezoelectric MEMS transducer, comprising a substrate and a piezoelectric layer formed on the substrate, wherein a cavity is further provided on the substrate, a bottom electrode is provided on a first surface of the piezoelectric layer, and a first differential electrode and a second differential electrode are provided on a second surface of the piezoelectric layer; wherein,

[0008] The first differential electrode and the second differential electrode are alternately distributed along a first direction on the second surface of the piezoelectric layer, and the bottom electrode is opposite to the first differential electrode and the second differential electrode;

[0009] The piezoelectric layer is a single crystal lithium niobate film or a single crystal lithium tantalate film. With the first direction as the positive direction of the x-axis of the right-hand coordinate system, the piezoelectric layer has a crystal orientation of a target Euler angle, so that the square value of the piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 1.52%.

[0010] In some embodiments, when the piezoelectric layer is a single crystal lithium niobate film, the target Euler angle is (0°±10°, 47°±10°, 90°±10°).

[0011] In some embodiments, a square value of a piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 12%.

[0012] In some embodiments, when the piezoelectric layer is a single crystal lithium niobate film, the target Euler angle is (0°±10°, 83°~110°, 0°±10°).

[0013] In some embodiments, a square value of a piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 8%.

[0014] In some embodiments, when the piezoelectric layer is a single crystal lithium niobate film, the target Euler angle is (0°±10°, 56°~110°, 0°±10°), (0°, 28°~66°, 66°~114°) or (0°, 57°~110°, -17°~17°).

[0015] In some embodiments, a square value of a piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 6.85%.

[0016] In some embodiments, when the piezoelectric layer is a single crystal lithium tantalate film, the target Euler angle is (0°±10°, 87°±10°, 0°±10°).

[0017] In some embodiments, a square value of the piezoelectric coupling coefficient of the piezoelectric layer in the first direction is 3.04%.

[0018] In some embodiments, when the piezoelectric layer is a single crystal lithium tantalate film, the target Euler angle is (0°±10°, 43°~131°, 0°±10°), (0°, 30°~68°, 65°~115°) or (0°, 44°~131°, -39°~39°).

[0019] In some embodiments, during operation,

[0020] The first differential electrode is connected to a positive voltage source, and the second differential electrode is connected to a negative voltage source, or

[0021] The first differential electrode is connected to a negative voltage source, and the second differential electrode is connected to a positive voltage source.

[0022] In some embodiments, each of the first differential electrodes has an opposite bottom electrode, and each of the second differential electrodes has an opposite bottom electrode.

[0023] In some embodiments, when observed from a direction perpendicular to the piezoelectric layer, a boundary of the bottom electrode opposite to each of the first differential electrodes in the first direction exceeds a boundary of the first differential electrode in the first direction, and a boundary of the bottom electrode in the second direction exceeds a boundary of the first differential electrode in the second direction, or a boundary of the bottom electrode opposite to each of the first differential electrodes in the first direction is within a boundary of the first differential electrode in the first direction, and a boundary of the bottom electrode in the second direction is within a boundary of the first differential electrode in the second direction;

[0024] Observed from the direction perpendicular to the piezoelectric layer, the boundary of the bottom electrode opposite to each second differential electrode in the first direction exceeds the boundary of the second differential electrode in the first direction, and the boundary of the bottom electrode in the second direction exceeds the boundary of the second differential electrode in the second direction, or the boundary of the bottom electrode opposite to each second differential electrode in the first direction is within the boundary of the second differential electrode in the first direction, and the boundary of the bottom electrode in the second direction is within the boundary of the second differential electrode in the second direction;

[0025] The second direction is opposite to the first direction.

[0026] In some embodiments, the bottom electrode is a continuous surface electrode.

[0027] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the bottom electrode in the first direction is between a boundary of the differential electrode at one end in the first direction and a boundary of the differential electrode at the second direction, and a boundary of the bottom electrode in the second direction is between a boundary of the differential electrode at the other end in the first direction and a boundary of the differential electrode at the second direction; or

[0028] Observed from a direction perpendicular to the piezoelectric layer, the boundary of the bottom electrode in the first direction is between the boundary of the differential electrode at one end in the first direction and the boundary of the cavity in the first direction, and the boundary of the bottom electrode in the second direction is between the boundary of the differential electrode at the other end in the second direction and the boundary of the cavity in the second direction; or

[0029] Observed from a direction perpendicular to the piezoelectric layer, a boundary of the bottom electrode in a first direction is outside a boundary of the cavity in the first direction, and a boundary of the bottom electrode in a second direction is outside a boundary of the cavity in the second direction;

[0030] The end differential electrode refers to a differential electrode located at the end of the first differential electrodes and the second differential electrodes alternately distributed in a first direction, and the second direction is opposite to the first direction.

[0031] In some embodiments, a width of each of the first differential electrodes along the first direction is equal to a width of each of the second differential electrodes along the first direction.

[0032] In some embodiments, a sum of widths of the first differential electrodes along the first direction is equal to a sum of widths of the second differential electrodes along the first direction.

[0033] In some embodiments, among the first differential electrodes and the second differential electrodes alternately distributed in the first direction, the width of the differential electrodes at the ends along the first direction is smaller than the width of the differential electrodes at the inside along the first direction.

[0034] In some embodiments, the first surface of the piezoelectric layer is a surface facing the cavity, and the second surface is a surface away from the cavity; or

[0035] The first surface of the piezoelectric layer is a surface facing away from the cavity, and the second surface is a surface facing the cavity.

[0036] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a first groove is formed by etching in a region of the piezoelectric layer between a boundary of the differential electrode in a third direction and a boundary of the cavity in the third direction; and / or

[0037] Observed from a direction perpendicular to the piezoelectric layer, a second groove is formed by etching in a region of the piezoelectric layer between a boundary of the differential electrode in a fourth direction and a boundary of the cavity in the fourth direction;

[0038] The third direction and the fourth direction are respectively perpendicular to the first direction, and the third direction and the fourth direction are also perpendicular to the thickness direction of the piezoelectric layer, and the third direction and the fourth direction are opposite in direction.

[0039] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the third direction coincides with a boundary of the cavity in the third direction; and / or

[0040] Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the fourth direction coincides with a boundary of the cavity in the fourth direction.

[0041] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the first direction coincides with a boundary of the cavity in the first direction, and a boundary of the first groove in the second direction coincides with a boundary of the cavity in the second direction; and / or

[0042] When viewed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the first direction coincides with a boundary of the cavity in the first direction, and a boundary of the second groove in the second direction coincides with a boundary of the cavity in the second direction;

[0043] The second direction is opposite to the first direction.

[0044] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the third direction is within a boundary of the cavity in the third direction; and / or

[0045] Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the fourth direction is within a boundary of the cavity in the fourth direction.

[0046] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the third direction is outside a boundary of the cavity in the third direction; and / or

[0047] Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the fourth direction is outside a boundary of the cavity in the fourth direction.

[0048] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the fourth direction is within a boundary of the cavity in the third direction, and a boundary of the second groove in the third direction is within a boundary of the cavity in the fourth direction;

[0049] The piezoelectric layer is removed in a region outside the boundary of the cavity in the third direction and in a region outside the boundary of the cavity in the fourth direction by an etching process.

[0050] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the first direction is outside a boundary of the cavity in the first direction; and / or

[0051] Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the first direction is outside a boundary of the cavity in the first direction.

[0052] In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the first direction is within a boundary of the cavity in the first direction; and / or

[0053] Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the first direction is within a boundary of the cavity in the first direction.

[0054] In some embodiments, the first groove and / or the second groove is formed by etching the piezoelectric layer to a target thickness along a direction perpendicular to the piezoelectric layer, wherein the target thickness is less than or equal to the thickness of the piezoelectric layer.

[0055] In some embodiments, the piezoelectric MEMS transducer includes a piezoelectric MEMS microphone, a piezoelectric MEMS ultrasonic transducer, or a piezoelectric MEMS speaker.

[0056] According to a second aspect of the embodiments of the present application, the present application further provides an electronic device, comprising the piezoelectric MEMS transducer described in any of the above embodiments.

[0057] In the present application, the differential electrode distribution direction and strain distribution direction of the piezoelectric MEMS transducer are controlled to be along a first direction. At this time, by controlling the crystal orientation of the piezoelectric layer, the piezoelectric layer has a higher piezoelectric coupling coefficient in the first direction, thereby improving the electromechanical coupling coefficient of the piezoelectric MEMS transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0059] Figure 1A A top view of a conventional piezoelectric MEMS transducer.

[0060] Figure 1B for Figure 1A Sectional view at AA'.

[0061] Figure 2 A schematic diagram of the positional relationship between the Euler transformation coordinate system and the right-handed coordinate system provided in an embodiment of the present application.

[0062] Figure 3A A top view of a piezoelectric MEMS transducer provided in the present application.

[0063] Figure 3B for Figure 3A Cross-sectional view of a piezoelectric MEMS transducer.

[0064] Figure 3C for Figure 3B Schematic diagram of the three states of the piezoelectric MEMS transducer.

[0065] Figure 4 When the Euler angle of lithium niobate is (0°, 47°, γ), Schematic diagram of the change with γ.

[0066] Figure 5A When the Euler angle γ of lithium niobate is 0°, Schematic diagram of the variation with β.

[0067] Figure 5B When the Euler angles β and γ of lithium niobate vary from 0° to 180°, let Schematic diagram of the Euler angle distribution of lithium niobate when it is greater than or equal to 50% of its global maximum value in the x-axis direction.

[0068] Figure 5C When the Euler angle γ of lithium tantalate is 0°, Schematic diagram of the variation with β.

[0069] Figure 5D When the Euler angles β and γ of lithium tantalate vary from 0° to 180°, let Schematic diagram of the Euler angle distribution of lithium tantalate when it is greater than or equal to 50% of its global maximum value in the x-axis direction.

[0070] Figure 6 A cross-sectional view of a piezoelectric MEMS transducer provided in the present application.

[0071] Figure 7 A top view of a piezoelectric MEMS transducer provided in the present application.

[0072] Figure 8 A top view of a piezoelectric MEMS transducer provided in the present application.

[0073] Fig. 9 A cross-sectional view of a piezoelectric MEMS transducer provided in the present application.

[0074] Fig.10 A cross-sectional view of a piezoelectric MEMS transducer provided in the present application.

[0075] Fig.11A A top view of a piezoelectric MEMS transducer provided in the present application.

[0076] Fig. 11B for Fig.11A Sectional view at AA'.

[0077] Fig. 11C for Fig.11A Sectional view at AA'.

[0078] Fig. 12A for Figure 3A and Figure 3B The schematic diagram of the optimal structural simulation results of a transducer with fixed boundaries on all four sides is shown.

[0079] Fig. 12B for Fig.11A and Fig. 11B Schematic diagram of the optimal structural simulation results of a transducer with fixed boundaries on both sides.

[0080] Fig. 12C Schematic diagram of displacement simulation results for a transducer with fixed boundaries on all four sides and a transducer with fixed boundaries on two sides. DETAILED DESCRIPTION

[0081] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in 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. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0082] With reference to the following description and accompanying drawings, the specific embodiments of the present application are disclosed in detail, indicating the way in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present application include many changes, modifications and equivalents.

[0083] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0084] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components.

[0085] In order to better understand the present application, the definition of Euler angles is first explained below.

[0086] Euler angles are a set of independent angular parameters used to uniquely determine the position of a fixed-point rotating rigid body. Euler angles are usually used to represent LN (lithium niobate) and LT (lithium tantalate) cuts. There are many ways to obtain Euler angles, and the most common one used in this application is:

[0087] For a reference system in three-dimensional space, the orientation of any coordinate system can be expressed by three Euler angles. The reference system is stationary, and the commonly used reference system is the right-handed coordinate system (such as Figure 2 The xyz coordinate system shown in the figure can be considered as the crystal axis coordinate system in the crystal. The Euler transformation coordinate system (such as Figure 2 The XYZ coordinate system shown in the figure is fixed to the rigid body and can be considered as a certain section or cut in the crystal. The Euler transformation coordinate system rotates with the rotation of the section. In this application, we set the Z axis of the Euler transformation coordinate system to be perpendicular to the target section, that is, along the thickness direction of the section, and the XY axis is located in the section. The English letter (N) represents the intersection of the xy plane and the XY plane. The Euler angles are defined as (α, β, γ) in the order of rotation around the zxz axis, where α is the angle of the crystal (lithium niobate or lithium tantalate) rotating around the z axis for the first time (when looking from the positive end of the z axis to the origin, the counterclockwise rotation direction is the positive rotation angle, and the clockwise direction is the negative rotation angle), and α also corresponds to the angle between the x axis and the intersection line N; β is the angle of the crystal rotating around the x axis, which also corresponds to the angle between the z axis and the Z axis; γ is the angle of the crystal rotating around the z axis for the second time, which also corresponds to the angle between the intersection line N and the X axis.

[0088] In LN film or LT film, the piezoelectric coupling coefficient K 31 The relationship with material parameters is as follows:

[0089]

[0090] Wherein, c represents the elastic coefficient matrix of the piezoelectric material, e represents the piezoelectric constant matrix of the piezoelectric material, and ε represents the dielectric constant matrix of the piezoelectric material.

[0091] In order to solve at least one of the above problems existing in the prior art, in a first aspect, the present application provides a piezoelectric MEMS transducer, such as Figure 3A and Figure 3BAs shown, a piezoelectric MEMS transducer provided in the present application includes a substrate 200 and a piezoelectric layer 100 formed on the substrate 200, a cavity 201 is also provided on the substrate 200, a bottom electrode 103 is provided on the first surface 100b of the piezoelectric layer 100, and a first differential electrode 101 and a second differential electrode 102 are provided on the second surface 100a of the piezoelectric layer 100; wherein, the first differential electrode 101 and the second differential electrode 102 are alternately distributed along a first direction on the second surface 100a of the piezoelectric layer 100, and the bottom electrode 103 and the first differential electrode 101 and the second differential electrode 102 are opposite; the piezoelectric layer 100 is a single crystal lithium niobate film or a single crystal lithium tantalate film, and with the first direction being the positive direction of the x-axis of the right-hand coordinate system, the piezoelectric layer 100 has a crystal orientation of a target Euler angle, so that the square value of the piezoelectric coupling coefficient of the piezoelectric layer 100 in the first direction is greater than or equal to 1.52%.

[0092] Specifically, the piezoelectric layer 100 can be bonded to the substrate 200 through the bonding layer 300, and the cavity 201 is located in the substrate 200 (or a dielectric layer is provided on the substrate 200, and the cavity 201 is provided in the dielectric layer). The piezoelectric layer 100, the bottom electrode 103, and the differential electrodes 101 and 102 in the region of the cavity 201 constitute the working region of the transducer, and the boundary 202 of the cavity 201 is a fixed support boundary.

[0093] The first direction refers to the positive direction of the x-axis or the negative direction of the x-axis, Figure 3A and Figure 3B The differential electrode distribution direction and strain distribution direction of the piezoelectric MEMS transducer shown are along the x-axis direction. At this time, by controlling the crystal orientation of the piezoelectric layer 100, the piezoelectric layer 100 has a higher piezoelectric coupling coefficient in the first direction, thereby improving the electromechanical coupling coefficient of the piezoelectric MEMS transducer. For example, by controlling the crystal orientation of the piezoelectric layer 100, the piezoelectric coupling coefficient K of the piezoelectric layer 100 is 31 The maximum value is distributed along the x-axis.

[0094] In the Euler angles (α, β, γ), the α and β angles determine a unique section, and the γ angle is the rotation angle of the x-axis / y-axis in the section (after rotation, it becomes the X-axis and Y-axis, where the x-axis / y-axis represents the crystal axis of the piezoelectric crystal), where the X-axis corresponds to the direction of sound wave propagation (corresponding to Figure 3A , Figure 7 , Figure 8 , Fig.11A In the horizontal direction), the piezoelectric coupling coefficient K 31 Related to device planar design.

[0095] Taking the piezoelectric layer 100 as a single crystal lithium niobate film as an example, when the LN Euler angle is (0°, 47°, 90°), reaches the global maximum value of 13.7%, and The global maximum of is distributed along the x-axis. Figure 4 When the Euler angle of lithium niobate is (0°, 47°, γ) As γ changes, it can be seen that the maximum value is 13.7% when γ is 90°, and the minimum value is 0 when γ is 39° and 141°.

[0096] The following embodiments take the x-axis direction as the piezoelectric coupling coefficient K 31 Taking the maximum value distribution direction or the distribution direction close to the maximum value as an example, the piezoelectric MEMS transducer provided in the present application is described.

[0097] When the piezoelectric layer is a single crystal lithium niobate film, the target Euler angle can be as follows:

[0098] Euler angles (0°, 47°, 90°) correspond to 137° rotated Y-cut cutting (the rotation angle of the rotated Y-cut is equal to β+90° or β-90°). The global maximum value of 13.7% is reached in the x-axis direction. Considering a certain error, the target Euler angle is determined to be (0°±10°, 47°±10°, 90°±10°).

[0099] When γ is 0°, The curve with β changes is as follows Figure 5A As shown. It can be seen that when the Euler angle is (0°, 83°, 0°), The local maximum value of 8% is reached in the x-axis direction, which is 58.4% of the global maximum value (13.7%). When it is greater than or equal to 50% of the global maximum value, its Euler angle is (0°, 56°~110°, 0°). Considering certain errors of α and γ, the target Euler angle is determined to be (0°±10°, 56°~110°, 0°±10°).

[0100] When β and γ both vary between 0° and 180°, let In the x-axis direction, it is greater than or equal to 50% of its global maximum value, that is, The distribution of Euler angles is as follows Figure 5B As shown. At this time, for the elliptical shadow area, the maximum and minimum values ​​of β are 66° and 28° respectively, and the maximum and minimum values ​​of γ are 114° and 66° respectively; for the other two areas, the maximum and minimum values ​​of β are 110° and 57° respectively, and the range of γ is -17° to 17° (taking into account the periodic characteristics of the Euler angle). Therefore, the target Euler angle is determined to be (0°, 28° to 66°, 66° to 114°) or (0°, 57° to 110°, -17° to 17°).

[0101] When the piezoelectric layer is a single crystal lithium tantalate film, the target Euler angle can be as follows:

[0102] The global maximum value (3.04%) in the x-axis direction corresponds to an Euler angle of (0°, 87°, 0°), which corresponds to a 177° rotated Y-cut (the rotation angle of the rotated Y-cut is equal to β+90° or β-90°), which is close to the Y-cut. Considering a certain error, the target Euler angle is determined to be (0°±10°, 87°±10°, 0°±10°).

[0103] When γ is 0°, The curve with β changes is as follows Figure 5C As shown. It can be seen that when the Euler angle is (0°, 87°, 0°), The global maximum value (3.04%) is reached in the x-axis direction. At this time, let When it is greater than or equal to 50% (i.e., 1.52%) of the global maximum value, the corresponding Euler angle range is (0°, 43°~131°, 0°). Considering certain errors of α and γ, the target Euler angle is determined to be (0°±10°, 43°~131°, 0°±10°).

[0104] When β and γ both vary between 0° and 180°, let In the x-axis direction, it is greater than or equal to 50% of its global maximum value, that is, The distribution of Euler angles is as follows Figure 5D As shown. At this time, for the elliptical shadow area, the maximum and minimum values ​​of β are 68° and 30° respectively, and the maximum and minimum values ​​of γ are 115° and 65° respectively; for the other two areas, the maximum and minimum values ​​of β are 131° and 44° respectively, and the range of γ is -39° to 39° (taking into account the periodic characteristics of the Euler angle). Therefore, the target Euler angle is determined to be (0°, 30° to 68°, 65° to 115°) or (0°, 44° to 131°, -39° to 39°).

[0105] like Figure 3B and Figure 3C As shown, in some embodiments, when working, the bottom electrode 103 is grounded, the first differential electrode 101 is connected to a positive voltage source, and the second differential electrode 102 is connected to a negative voltage source; or, when working, the bottom electrode 103 is grounded, the first differential electrode 101 is connected to a negative voltage source, and the second differential electrode 102 is connected to a positive voltage source. In other embodiments, as Figure 3BAs shown, when each first differential electrode 101 has a bottom electrode 103 opposite to it, and each second differential electrode 102 has a bottom electrode 103 opposite to it, during operation, the first differential electrode 101 is connected to a positive voltage source, and the bottom electrode 103 opposite to the first differential electrode 101 is connected to a negative voltage source, while the second differential electrode 102 is connected to a negative voltage source, and the bottom electrode 103 opposite to the second differential electrode 102 is connected to a positive voltage source; or, during operation, the first differential electrode 101 is connected to a negative voltage source, and the bottom electrode 103 opposite to the first differential electrode 101 is connected to a positive voltage source, while the second differential electrode 102 is connected to a positive voltage source, and the bottom electrode 103 opposite to the second differential electrode 102 is connected to a negative voltage source.

[0106] Specifically, during operation, the first differential electrode 101 and the second differential electrode 102 input / output differential electrical signals, the bottom electrode 103 is grounded, and the piezoelectric layer area covered by the first differential electrode 101 and the piezoelectric layer area covered by the second differential electrode 102 undergo opposite strains (the piezoelectric layer area covered by the first differential electrode 101 undergoes positive strain, and the piezoelectric layer area covered by the second differential electrode 102 undergoes negative strain, or the piezoelectric layer area covered by the first differential electrode 101 undergoes negative strain, and the piezoelectric layer area covered by the second differential electrode 102 undergoes positive strain). Figure 3C As shown, from top to bottom, the first one is a schematic diagram of the initial state of the transducer when no differential signal is applied; the second one is a schematic diagram of a positive voltage applied to the first differential electrode 101 of the transducer and a negative voltage applied to the second differential electrode 102, and the piezoelectric layer area covered by the first differential electrode 101 undergoes negative strain, while the piezoelectric layer area covered by the second differential electrode 102 undergoes positive strain; the third one is a schematic diagram of a negative voltage applied to the first differential electrode 101 of the transducer and a positive voltage applied to the second differential electrode 102, and the piezoelectric layer area covered by the first differential electrode 101 undergoes positive strain, while the piezoelectric layer area covered by the second differential electrode 102 undergoes negative strain. If the polarization directions of the piezoelectric layers are opposite, when a positive voltage is applied to the first differential electrode and a negative voltage is applied to the second differential electrode, the piezoelectric layer will undergo positive strain in the piezoelectric layer area covered by the first differential electrode and negative strain in the piezoelectric layer area covered by the second differential electrode; when a negative voltage is applied to the first differential electrode and a positive voltage is applied to the second differential electrode, the piezoelectric layer will undergo negative strain in the piezoelectric layer area covered by the first differential electrode and positive strain in the piezoelectric layer area covered by the second differential electrode.

[0107] refer to Figure 3B, when each first differential electrode 101 has a bottom electrode 103 opposite to it, and each second differential electrode 102 has a bottom electrode 103 opposite to it, in some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the bottom electrode 103 opposite to each first differential electrode 101 in the first direction exceeds the boundary of the first differential electrode 101 in the first direction, and the boundary of the bottom electrode 103 in the second direction exceeds the boundary of the first differential electrode 101 in the second direction, or the boundary of the bottom electrode 103 opposite to each first differential electrode 101 in the first direction is within the boundary of the first differential electrode 101 in the first direction, and the boundary of the bottom electrode 103 in the second direction is within the boundary of the first differential electrode 101 in the first direction. The second differential electrode 101 is within the boundary of the second direction; when observed from the direction perpendicular to the piezoelectric layer 100, the boundary of the bottom electrode 103 opposite to each second differential electrode 102 in the first direction exceeds the boundary of the second differential electrode 102 in the first direction, and the boundary of the bottom electrode 103 in the second direction exceeds the boundary of the second differential electrode 102 in the second direction, or the boundary of the bottom electrode 103 opposite to each second differential electrode 102 in the first direction is within the boundary of the second differential electrode 102 in the first direction, and the boundary of the bottom electrode 103 in the second direction is within the boundary of the second differential electrode 102 in the second direction; wherein the second direction is opposite to the first direction, for example, as Figure 3B As shown, when the first direction is the positive direction of the x-axis (right direction), the second direction refers to the negative direction of the x-axis (left direction).

[0108] Specifically, refer to Figure 3B , when each first differential electrode 101 has a corresponding bottom electrode 103, and each second differential electrode 102 has a corresponding bottom electrode 103, in some embodiments, observed from a direction perpendicular to the piezoelectric layer 100, the left boundary of the bottom electrode 103 corresponding to the first differential electrode 101 is outside the left boundary of the first differential electrode 101, and the right boundary is outside the right boundary of the first differential electrode 101, and the left boundary of the bottom electrode 103 corresponding to the second differential electrode 102 is outside the left boundary of the second differential electrode 102, and the right boundary is outside the right boundary of the second differential electrode 102.

[0109] In other embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the left boundary of the bottom electrode 103 corresponding to the first differential electrode 101 is within the left boundary of the first differential electrode 101, and the right boundary is within the right boundary of the first differential electrode 101; the left boundary of the bottom electrode 103 corresponding to the second differential electrode 102 is outside the left boundary of the second differential electrode 102, and the right boundary is outside the right boundary of the second differential electrode 102.

[0110] In some other embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the left boundary of the bottom electrode 103 corresponding to the first differential electrode 101 is outside the left boundary of the first differential electrode 101, and the right boundary is outside the right boundary of the first differential electrode 101; the left boundary of the bottom electrode 103 corresponding to the second differential electrode 102 is within the left boundary of the second differential electrode 102, and the right boundary is within the right boundary of the second differential electrode 102.

[0111] In some further embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the left boundary of the bottom electrode 103 corresponding to the first differential electrode 101 is within the left boundary of the first differential electrode 101, and the right boundary is within the right boundary of the first differential electrode 101; the left boundary of the bottom electrode 103 corresponding to the second differential electrode 102 is within the left boundary of the second differential electrode 102, and the right boundary is within the right boundary of the second differential electrode 102.

[0112] like Figure 6 As shown, in some embodiments, the bottom electrode 103 is a continuous surface electrode.

[0113] refer to Figure 6 When the bottom electrode 103 is a continuous surface electrode, in some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the bottom electrode 103 in the first direction is between the boundary of the differential electrode in the first direction and the boundary of the second direction at one end, and the boundary of the bottom electrode 103 in the second direction is between the boundary of the differential electrode in the first direction and the boundary of the second direction at the other end; in other embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the bottom electrode 103 in the first direction is between the boundary of the differential electrode in the first direction at one end and the boundary of the cavity 201 in the first direction, and the boundary of the bottom electrode 103 in the second direction is between the boundary of the differential electrode in the first direction and the boundary of the cavity 201 in the first direction at one end. 3 in the second direction is between the boundary of the other end differential electrode in the second direction and the boundary of the cavity 201 in the second direction; in some other embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the bottom electrode 103 in the first direction is outside the boundary of the cavity 201 in the first direction, and the boundary of the bottom electrode 103 in the second direction is outside the boundary of the cavity 201 in the second direction; wherein the end differential electrode refers to a differential electrode located at the end of the first differential electrode 101 and the second differential electrode 102 alternately distributed in the first direction, and the second direction is opposite to the first direction, for example, Figure 6 As shown, when the first direction is the positive direction of the x-axis (right direction), the second direction refers to the negative direction of the x-axis (left direction).

[0114] Specifically, refer to Figure 6, when the bottom electrode 103 is a continuous surface electrode, in some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, in some embodiments, the left boundary of the bottom electrode 103 is between the left boundary and the right boundary of the leftmost differential electrode 102, and the right boundary is between the left boundary and the right boundary of the rightmost differential electrode 102. In other embodiments, the left boundary of the bottom electrode 103 is between the left boundary of the leftmost differential electrode 102 and the left boundary of the cavity 201, and the right boundary is between the right boundary of the rightmost differential electrode 102 and the right boundary of the cavity 201. In still other embodiments, the left boundary of the bottom electrode 103 is outside the left boundary of the cavity 201, and the right boundary is outside the right boundary of the cavity 201.

[0115] like Figure 3B As shown, in some embodiments, among the first differential electrodes 101 and the second differential electrodes 102 alternately distributed in the first direction, the width of the differential electrodes 102 at the ends along the first direction is smaller than the width of the differential electrodes 101 at the inside along the first direction.

[0116] like Figure 7 As shown, in some embodiments, the width of each first differential electrode 101 along the first direction is equal to the width of each second differential electrode 102 along the first direction.

[0117] like Figure 3B As shown, in some embodiments, the number of the first differential electrode 101 is one, and the number of the second differential electrode 102 is two. Figure 8 As shown, in some other embodiments, the number of the first differential electrodes 101 is two, and the number of the second differential electrodes 102 is three. Of course, there may be more first differential electrodes 101 and second differential electrodes 102 in other embodiments.

[0118] In some embodiments, a sum of widths of the first differential electrodes along the first direction is equal to a sum of widths of the second differential electrodes along the first direction.

[0119] like Figure 3B As shown, in some embodiments, the first surface 100b of the piezoelectric layer 100 is a surface facing the cavity 201, and the second surface 100a is a surface away from the cavity 201; Fig. 9 and Fig.10 As shown, in some other embodiments, the first surface 100 b of the piezoelectric layer 100 is a surface facing away from the cavity 201 , and the second surface 100 a is a surface facing the cavity 201 .

[0120] Specifically, in some embodiments, Figure 3BAs shown, the first differential electrode 101 and the second differential electrode 102 are disposed on the upper surface of the piezoelectric layer 100, and the bottom electrode 103 is disposed on the lower surface of the piezoelectric layer 100. In other embodiments, as Fig. 9 and Fig.10 As shown, the first differential electrode 101 and the second differential electrode 102 are disposed on the lower surface of the piezoelectric layer 100 , and the bottom electrode 103 is disposed on the upper surface of the piezoelectric layer 100 .

[0121] like Fig.10 As shown, in other embodiments, the cavity 201 disposed on the substrate 200 is a through hole in a direction perpendicular to the piezoelectric layer 100 , and the sidewall of the cavity 201 may be vertical or inclined.

[0122] like Fig.11A , Fig. 11B as well as Fig. 11C As shown, in some embodiments, when viewed from a direction perpendicular to the piezoelectric layer 100, the piezoelectric layer 100 is formed with a first groove 104 by etching in a region between the boundary of the differential electrodes 101 and 102 in the third direction and the boundary of the cavity 201 in the third direction; and / or

[0123] Observed from a direction perpendicular to the piezoelectric layer 100 , the piezoelectric layer 100 is etched to form a second groove 105 in a region between the boundary of the differential electrodes 101 and 102 in the fourth direction and the boundary of the cavity 201 in the fourth direction;

[0124] The third direction and the fourth direction are respectively perpendicular to the first direction, and the third direction and the fourth direction are also perpendicular to the thickness direction of the piezoelectric layer 100 , and the third direction and the fourth direction are opposite in direction.

[0125] Specifically, when the first direction is the positive direction of x (right direction), the third direction is the positive direction of y axis (upward direction), and the fourth direction is the negative direction of y axis (downward direction). In this embodiment, the piezoelectric layer 100 is etched between the upper boundary of the differential electrodes 101, 102 and the upper boundary of the cavity 201, and between the lower boundary of the differential electrodes 101, 102 and the lower boundary of the cavity 201 to form the first groove 104 and / or the second groove 105, so that the upper boundary 106 and / or the lower boundary 107 of the working area become free boundaries. The first groove 104 and the second groove 105 form a decoupling structure of the transducer along the distribution direction of the differential electrodes. The decoupling structure makes the boundary constraint of the transducer along the distribution direction of the differential electrodes smaller than the boundary constraint perpendicular to the distribution direction of the differential electrodes, which can further improve the electromechanical coupling coefficient.

[0126] like Fig.11A , Fig. 11B as well as Fig. 11CAs shown, in some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the first groove 104 in the third direction coincides with the boundary of the cavity 201 in the third direction; and / or the boundary of the second groove 105 in the fourth direction coincides with the boundary of the cavity 201 in the fourth direction.

[0127] Specifically, from Fig.11A From the perspective of FIG. 2 , the upper boundary of the first trench 104 coincides with the upper boundary of the cavity 201 , and the lower boundary of the second trench 105 coincides with the lower boundary of the cavity 201 .

[0128] like Fig.11A , Fig. 11B as well as Fig. 11C As shown, in some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the first groove 104 in the first direction coincides with the boundary of the cavity 201 in the first direction, and the boundary of the first groove 104 in the second direction coincides with the boundary of the cavity 201 in the second direction; and / or, the boundary of the second groove 105 in the first direction coincides with the boundary of the cavity 201 in the first direction, and the boundary of the second groove 105 in the second direction coincides with the boundary of the cavity 201 in the second direction; wherein, the second direction is opposite to the first direction.

[0129] Specifically, from Fig.11A From the perspective of FIG. 1 , the right boundary of the first groove 104 coincides with the right boundary of the cavity 201 , and the left boundary of the first groove 104 coincides with the left boundary of the cavity 201 ; and / or, the right boundary of the second groove 105 coincides with the right boundary of the cavity 201 , and the left boundary of the second groove 105 coincides with the left boundary of the cavity 201 .

[0130] Fig. 12A for Figure 3A and Figure 3B The schematic diagram of the optimal structure simulation results of the transducer with four fixed boundaries is shown, and the electromechanical coupling coefficient is Kt 2 =4.7%; Fig. 12B for Fig.11A and Fig. 11B The schematic diagram of the optimal structure simulation result of the transducer with fixed support boundaries on both sides is shown, and the electromechanical coupling coefficient is Kt 2 =5.9%. Fig. 12C This is a schematic diagram of the displacement simulation results of a transducer with fixed boundaries on all four sides and a transducer with fixed boundaries on two sides. It can be seen that the displacement of the transducer with a decoupling structure is larger.

[0131] See also Fig.11AIn some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the first groove 104 in the third direction is within the boundary of the cavity 201 in the third direction; and / or the boundary of the second groove 105 in the fourth direction is within the boundary of the cavity 201 in the fourth direction.

[0132] Specifically, see Fig.11A , viewed from a direction perpendicular to the piezoelectric layer 100 , an upper boundary of the first groove 104 is within an upper boundary of the cavity 201 , and / or a lower boundary of the second groove 105 is within a lower boundary of the cavity 201 .

[0133] See also Fig.11A In some embodiments, when viewed from a direction perpendicular to the piezoelectric layer 100, the boundary of the first groove 104 in the third direction is outside the boundary of the cavity 201 in the third direction; and / or the boundary of the second groove 105 in the fourth direction is outside the boundary of the cavity 201 in the fourth direction.

[0134] Specifically, when viewed from a direction perpendicular to the piezoelectric layer 100 , an upper boundary of the first groove 104 is outside an upper boundary of the cavity 201 , and / or a lower boundary of the second groove 105 is outside a lower boundary of the cavity 201 .

[0135] See also Fig.11A In some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, the boundary of the first groove 104 in the fourth direction is within the boundary of the cavity 201 in the third direction, and the boundary of the second groove 105 in the third direction is within the boundary of the cavity 201 in the fourth direction; the area of ​​the piezoelectric layer 100 outside the boundary of the cavity 201 in the third direction and the area of ​​the cavity 201 outside the boundary in the fourth direction are removed by an etching process.

[0136] Specifically, when observed from a direction perpendicular to the piezoelectric layer 100, the lower boundary of the first groove 104 is within the upper boundary of the cavity 201, and the upper boundary of the second groove 105 is within the lower boundary of the cavity 201; the area of ​​the piezoelectric layer 100 outside the upper boundary of the cavity 201 and the area outside the lower boundary of the cavity 201 are removed by an etching process.

[0137] See also Fig.11A In some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, a boundary of the first groove 104 in the first direction is outside a boundary of the cavity 201 in the first direction; and / or a boundary of the second groove 105 in the first direction is outside a boundary of the cavity 201 in the first direction.

[0138] Specifically, when viewed from a direction perpendicular to the piezoelectric layer 100 , the right boundary of the first groove 104 is outside the right boundary of the cavity 201 , and / or the right boundary of the second groove 105 is outside the right boundary of the cavity 201 .

[0139] See also Fig.11A In some embodiments, when observed from a direction perpendicular to the piezoelectric layer 100, a boundary of the first groove 104 in the first direction is within a boundary of the cavity 201 in the first direction; and / or a boundary of the second groove 105 in the first direction is within a boundary of the cavity 201 in the first direction.

[0140] Specifically, when viewed from a direction perpendicular to the piezoelectric layer 100 , the right boundary of the first groove 104 is within the right boundary of the cavity 201 , and / or the right boundary of the second groove 105 is within the right boundary of the cavity 201 .

[0141] See also Fig. 11B and Fig. 11C In some embodiments, the first groove 104 and / or the second groove 105 are formed by etching the piezoelectric layer 100 to a target thickness along a direction perpendicular to the piezoelectric layer 100 , wherein the target thickness is less than or equal to the thickness of the piezoelectric layer 100 .

[0142] Specifically, when the target thickness is equal to the thickness of the piezoelectric layer 100, Fig. 11B As shown, the first groove 104 and / or the second groove 105 penetrates the piezoelectric layer 100; when the target thickness is less than the thickness of the piezoelectric layer 100, as shown in Fig. 11C As shown, the piezoelectric layer 100 is partially etched.

[0143] In some embodiments, the piezoelectric MEMS transducer includes a piezoelectric MEMS microphone, a piezoelectric MEMS ultrasonic transducer, or a piezoelectric MEMS speaker.

[0144] According to a second aspect of the embodiments of the present application, the present application further provides an electronic device, comprising the piezoelectric MEMS transducer described in any of the above embodiments.

[0145] The performance of the piezoelectric MEMS transducer is mainly utilized in the electronic device structure, thereby realizing high-performance electronic devices. The structure of the piezoelectric MEMS transducer can refer to the embodiment of the first aspect of the present application, and will not be described in detail here.

[0146] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. The orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0147] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0148] Specific embodiments are used in this application to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core idea of ​​this application. At the same time, for those skilled in the art, according to the idea of ​​this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on this application.

Claims

1. A piezoelectric MEMS transducer, characterized in that: It comprises a substrate and a piezoelectric layer formed on the substrate, wherein a cavity is further provided on the substrate, a bottom electrode is provided on the first surface of the piezoelectric layer, and a first differential electrode and a second differential electrode are provided on the second surface of the piezoelectric layer; wherein, The first differential electrode and the second differential electrode are alternately distributed along a first direction on the second surface of the piezoelectric layer, and the bottom electrode is opposite to the first differential electrode and the second differential electrode; The piezoelectric layer is a single crystal lithium niobate film or a single crystal lithium tantalate film. With the first direction as the positive direction of the x-axis of the right-hand coordinate system, the piezoelectric layer has a crystal orientation of a target Euler angle, so that the square value of the piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 1.52%.

2. The piezoelectric MEMS transducer according to claim 1, characterized in that: When the piezoelectric layer is a single crystal lithium niobate film, the target Euler angle is (0°±10°, 47°±10°, 90°±10°).

3. The piezoelectric MEMS transducer according to claim 2, characterized in that: A square value of a piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 12%.

4. The piezoelectric MEMS transducer according to claim 1, characterized in that: When the piezoelectric layer is a single crystal lithium niobate film, the target Euler angle is (0°±10°, 83°-110°, 0°±10°).

5. The piezoelectric MEMS transducer according to claim 4, characterized in that: A square value of a piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 8%.

6. The piezoelectric MEMS transducer according to claim 1, characterized in that: When the piezoelectric layer is a single crystal lithium niobate film, the target Euler angle is (0°±10°, 56°~110°, 0°±10°), (0°, 28°~66°, 66°~114°) or (0°, 57°~110°, -17°~17°).

7. The piezoelectric MEMS transducer according to claim 6, characterized in that: A square value of a piezoelectric coupling coefficient of the piezoelectric layer in the first direction is greater than or equal to 6.85%.

8. The piezoelectric MEMS transducer according to claim 1, characterized in that: When the piezoelectric layer is a single crystal lithium tantalate film, the target Euler angle is (0°±10°, 87°±10°, 0°±10°).

9. The piezoelectric MEMS transducer according to claim 8, characterized in that: The square value of the piezoelectric coupling coefficient of the piezoelectric layer in the first direction is 3.04%.

10. The piezoelectric MEMS transducer according to claim 1, characterized in that: When the piezoelectric layer is a single crystal lithium tantalate film, the target Euler angle is (0°±10°, 43°~131°, 0°±10°), (0°, 30°~68°, 65°~115°) or (0°, 44°~131°, -39°~39°).

11. The piezoelectric MEMS transducer according to any one of claims 1 to 10, characterized in that: At work, The first differential electrode is connected to a positive voltage source, and the second differential electrode is connected to a negative voltage source, or The first differential electrode is connected to a negative voltage source, and the second differential electrode is connected to a positive voltage source.

12. The piezoelectric MEMS transducer according to claim 11, characterized in that: Each of the first differential electrodes has an opposite bottom electrode, and each of the second differential electrodes has an opposite bottom electrode.

13. The piezoelectric MEMS transducer according to claim 12, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the bottom electrode opposite to each of the first differential electrodes in the first direction exceeds a boundary of the first differential electrode in the first direction, and a boundary of the bottom electrode in the second direction exceeds a boundary of the first differential electrode in the second direction, or a boundary of the bottom electrode opposite to each of the first differential electrodes in the first direction is within a boundary of the first differential electrode in the first direction, and a boundary of the bottom electrode in the second direction is within a boundary of the first differential electrode in the second direction; Observed from the direction perpendicular to the piezoelectric layer, the boundary of the bottom electrode opposite to each second differential electrode in the first direction exceeds the boundary of the second differential electrode in the first direction, and the boundary of the bottom electrode in the second direction exceeds the boundary of the second differential electrode in the second direction, or the boundary of the bottom electrode opposite to each second differential electrode in the first direction is within the boundary of the second differential electrode in the first direction, and the boundary of the bottom electrode in the second direction is within the boundary of the second differential electrode in the second direction; The second direction is opposite to the first direction.

14. The piezoelectric MEMS transducer according to claim 11, characterized in that: The bottom electrode is a continuous surface electrode.

15. The piezoelectric MEMS transducer according to claim 14, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, the boundary of the bottom electrode in the first direction is between the boundary of the differential electrode at one end in the first direction and the boundary of the differential electrode at the second direction, and the boundary of the bottom electrode in the second direction is between the boundary of the differential electrode at the other end in the first direction and the boundary of the differential electrode at the second direction; or Observed from a direction perpendicular to the piezoelectric layer, the boundary of the bottom electrode in the first direction is between the boundary of the differential electrode at one end in the first direction and the boundary of the cavity in the first direction, and the boundary of the bottom electrode in the second direction is between the boundary of the differential electrode at the other end in the second direction and the boundary of the cavity in the second direction; or Observed from a direction perpendicular to the piezoelectric layer, a boundary of the bottom electrode in a first direction is outside a boundary of the cavity in the first direction, and a boundary of the bottom electrode in a second direction is outside a boundary of the cavity in the second direction; The end differential electrode refers to a differential electrode located at the end of the first differential electrodes and the second differential electrodes alternately distributed in a first direction, and the second direction is opposite to the first direction.

16. The piezoelectric MEMS transducer according to claim 11, characterized in that: The width of each of the first differential electrodes along the first direction is equal to the width of each of the second differential electrodes along the first direction.

17. The piezoelectric MEMS transducer according to claim 11, characterized in that: The sum of the widths of the first differential electrodes along the first direction is equal to the sum of the widths of the second differential electrodes along the first direction.

18. The piezoelectric MEMS transducer according to claim 11, characterized in that: Among the first differential electrodes and the second differential electrodes alternately distributed in the first direction, the width of the differential electrodes at the ends along the first direction is smaller than the width of the differential electrodes at the inside along the first direction.

19. The piezoelectric MEMS transducer according to claim 11, characterized in that: The first surface of the piezoelectric layer is a surface facing the cavity, and the second surface is a surface away from the cavity; or The first surface of the piezoelectric layer is a surface facing away from the cavity, and the second surface is a surface facing the cavity.

20. The piezoelectric MEMS transducer according to claim 11, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a first groove is formed by etching in a region of the piezoelectric layer between a boundary of the differential electrode in a third direction and a boundary of the cavity in the third direction; and / or Observed from a direction perpendicular to the piezoelectric layer, a second groove is formed by etching in a region of the piezoelectric layer between a boundary of the differential electrode in a fourth direction and a boundary of the cavity in the fourth direction; The third direction and the fourth direction are respectively perpendicular to the first direction, and the third direction and the fourth direction are also perpendicular to the thickness direction of the piezoelectric layer, and the third direction and the fourth direction are opposite in direction.

21. The piezoelectric MEMS transducer according to claim 20, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the third direction coincides with a boundary of the cavity in the third direction; and / or Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the fourth direction coincides with a boundary of the cavity in the fourth direction.

22. The piezoelectric MEMS transducer according to claim 21, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the first direction coincides with a boundary of the cavity in the first direction, and a boundary of the first groove in the second direction coincides with a boundary of the cavity in the second direction; and / or When viewed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the first direction coincides with a boundary of the cavity in the first direction, and a boundary of the second groove in the second direction coincides with a boundary of the cavity in the second direction; The second direction is opposite to the first direction.

23. The piezoelectric MEMS transducer according to claim 20, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the third direction is within a boundary of the cavity in the third direction; and / or Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the fourth direction is within a boundary of the cavity in the fourth direction.

24. The piezoelectric MEMS transducer according to claim 20, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the third direction is outside a boundary of the cavity in the third direction; and / or Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the fourth direction is outside a boundary of the cavity in the fourth direction.

25. The piezoelectric MEMS transducer according to claim 20, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the fourth direction is within a boundary of the cavity in the third direction, and a boundary of the second groove in the third direction is within a boundary of the cavity in the fourth direction; The piezoelectric layer is removed in a region outside the boundary of the cavity in the third direction and in a region outside the boundary of the cavity in the fourth direction by an etching process.

26. The piezoelectric MEMS transducer according to claim 20, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the first direction is outside a boundary of the cavity in the first direction; and / or Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the first direction is outside a boundary of the cavity in the first direction.

27. The piezoelectric MEMS transducer according to claim 20, characterized in that: Observed from a direction perpendicular to the piezoelectric layer, a boundary of the first groove in the first direction is within a boundary of the cavity in the first direction; and / or Observed from a direction perpendicular to the piezoelectric layer, a boundary of the second groove in the first direction is within a boundary of the cavity in the first direction.

28. The piezoelectric MEMS transducer according to claim 20, characterized in that: The first groove and / or the second groove are formed by etching the piezoelectric layer to a target thickness along a direction perpendicular to the piezoelectric layer, wherein the target thickness is less than or equal to the thickness of the piezoelectric layer.

29. The piezoelectric MEMS transducer according to claim 1, characterized in that: The piezoelectric MEMS transducer includes a piezoelectric MEMS microphone, a piezoelectric MEMS ultrasonic transducer or a piezoelectric MEMS speaker.

30. An electronic device, characterized in that: The piezoelectric MEMS transducer comprises any one of claims 1 to 29.

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