Acoustic wave resonator, acoustic wave filter and acoustic wave filter module

Abstract

The present application relates to the technical field of semiconductors, and in particular to an acoustic wave resonator, an acoustic wave filter and an acoustic wave filter module. The acoustic wave resonator at least comprises: a piezoelectric film and an interdigital electrode; a preset crystal axis in the piezoelectric film is taken as a first reference axis, the normal direction of interdigital electrode pairs is taken as a second reference axis, and a preset included angle is formed between the first reference axis and the second reference axis; and the average tangential direction of a first gap trajectory and the average tangential direction of a second gap trajectory in the interdigital electrode meet a preset condition. An electromechanical coupling coefficient of the acoustic wave resonator is adjusted by changing the acoustic wave propagation direction in an acoustic wave surface. Moreover, by designing a first gap trajectory tangential angle and a second gap trajectory tangential angle, energy leakage caused by excessive energy flux incident angles is avoided while the electromechanical coupling coefficient of the acoustic wave resonator is changed. Therefore, acoustic wave resonators with different electromechanical coupling coefficients can be implemented on a same piezoelectric film, and then acoustic wave filters with different relative bandwidths are implemented.

Description

Acoustic wave resonator, acoustic wave filter and acoustic wave filter module Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to an acoustic wave resonator, an acoustic wave filter, and an acoustic wave filter module. Background Art

[0002] With the development of mobile communication systems, the number of acoustic wave filters in the RF front-end is increasing. For example, the number of acoustic wave filters in smartphones has increased to 50 or even more than 100. Acoustic wave filters in different frequency bands generally have different frequencies and bandwidths. In addition, some frequency bands have similar frequencies but significantly different bandwidths. For example, Band 3, Band 4, and Band 9 all operate between 1.7 and 1.8 GHz, but have bandwidths of 75 MHz, 45 MHz, and 35 MHz, respectively. Acoustic wave filters in different frequency bands have different requirements for the frequency and electromechanical coupling coefficient of the acoustic wave resonators that constitute the acoustic wave filters.

[0003] At present, for acoustic wave resonators that constitute acoustic wave filters of specific frequency bands, they are often realized through specific material structures. For example, for bulk acoustic wave (BAW) devices based on aluminum nitride films, different scandium doping concentrations are required to achieve different relative bandwidths. In addition, the thickness of the piezoelectric film needs to be changed to achieve different operating frequencies. For surface acoustic wave (SAW) devices based on piezoelectric heterogeneous substrates, the required frequency is met by changing the electrode period, and different relative bandwidths are achieved by selecting different piezoelectric material cuts. Therefore, whether for BAW devices or SAW devices, to achieve different frequency bands, it is necessary to design specific material structures or compositions. This situation has caused great trouble for both the production and processing of materials and the preparation of acoustic wave devices, limiting the large-scale application of acoustic wave devices.

[0004] Summary of the Invention

[0005] In order to solve the above technical problems, the present application proposes an acoustic wave resonator, an acoustic wave filter and an acoustic wave filter module.

[0006] On the one hand, an embodiment of the present application provides an acoustic wave resonator, comprising: a piezoelectric film and a top electrode disposed on a first surface of the piezoelectric film;

[0007] The top electrode includes a first finger electrode and a second finger electrode;

[0008] The first finger-shaped electrode includes a preset number of first electrode fingers and first dummy finger electrodes, and the first electrode fingers are spaced apart from the first dummy finger electrodes;

[0009] The second finger-shaped electrode includes a preset number of second electrode fingers and second dummy finger electrodes, and the second electrode fingers are spaced apart from the second dummy finger electrodes;

[0010] The first electrode fingers and the second electrode fingers are arranged crosswise, and adjacent first electrode fingers and second electrode fingers form an interdigitated electrode pair;

[0011] The first electrode finger strips are arranged opposite to the second dummy electrode finger strips, and a first gap track is formed between the first electrode finger strips and the second dummy electrode finger strips;

[0012] The second electrode finger strip is arranged opposite to the first dummy electrode, and a second gap track is formed between the second electrode finger strip and the first dummy electrode;

[0013] A preset crystal axis in the piezoelectric film is used as a first reference axis, a normal direction of the interdigitated electrode pair is used as a second reference axis, and a preset angle is formed between the first reference axis and the second reference axis;

[0014] The angle between the average tangent of the first gap track and the second reference axis is the first gap track tangential angle, and the angle between the average tangent of the second gap track and the second reference axis is the second gap track tangential angle. The first gap track tangential angle and the second gap track tangential angle meet the preset conditions.

[0015] In some optional embodiments, the electromechanical coupling coefficient of the acoustic wave resonator satisfies the following condition: (k2 max -k2 30° ) / k2 max ≥30%;

[0016] Among them, k2 max is the maximum value of the electromechanical coupling coefficient when the sound wave propagates in different directions, k2 30° is the electromechanical coupling coefficient after the crystal axis orientation is rotated 30° relative to the maximum electromechanical coupling value.

[0017] In some optional embodiments, the material of the piezoelectric film is one of lithium niobate, lithium tantalate, and potassium niobate.

[0018] In some optional embodiments, the piezoelectric film is an X-cut lithium niobate or lithium tantalate, the target acoustic wave mode in the acoustic wave resonator is a 0th-order horizontal shear mode, and the preset crystal axis is the Y-axis;

[0019] The preset angles are 0° to 45°, or 130° to 180°.

[0020] In some optional embodiments, the piezoelectric film is a rotated Y-cut lithium niobate or lithium tantalate, the target acoustic wave mode in the acoustic wave resonator is a 0th-order horizontal shear mode, and the preset crystal axis is the X-axis;

[0021] The preset angle is from -40° to 40°.

[0022] In some optional embodiments, the direction of the acoustic wave energy flow of the acoustic wave resonator is taken as the third reference axis, and the angle between the second reference axis and the third reference axis is taken as the reference energy flow angle;

[0023] The tangential angle of the first gap trajectory meets the following preset conditions:

[0024] in, is the tangential angle of the first gap trajectory, τ' is the reference energy flow angle;

[0025] The tangential angle of the second gap trajectory meets the following preset conditions:

[0026] in, is the tangential angle of the second gap trajectory, and τ' is the reference energy flow angle.

[0027] In some optional embodiments, the angle between the tangent of the first gap trajectory at any of the first electrode fingers and the third reference axis is the first energy flow incident angle, the angle between the tangent of the second gap trajectory at any of the second electrode fingers and the third reference axis is the second energy flow incident angle, and the maximum value of at least one first energy flow incident angle or the maximum value of at least one second energy flow incident angle is greater than or equal to 1°.

[0028] In some optional embodiments, the reference energy flow angle is not equal to 0.

[0029] In some optional embodiments, the length of the first dummy electrode satisfies the following conditions: 1i ≥5λ×tan(|γ 2i -τ'|),

[0030] Among them, L 1i is the length of the first pseudo-finger electrode in the first finger electrode, γ 2i is the angle between the tangent line of the second gap trajectory at the i-th first pseudo-finger electrode and the second reference axis, and τ' is the reference energy flow angle;

[0031] The length of the second fake finger electrode meets the following conditions: L 2i ≥5λ×tan(|γ 1i -τ'|);

[0032] Among them, L 2i is the length of the i-th second pseudo-finger electrode in the second finger electrode, γ1i is the angle between the tangent line of the first gap track at the i-th second dummy electrode and the second reference axis, and τ' is the reference energy flow angle.

[0033] In some optional embodiments, the first gap trajectory is a straight line; and / or,

[0034] The second gap trajectory is a straight line.

[0035] In some optional embodiments, the first gap track and the second gap track are parallel.

[0036] In some optional embodiments, the distance between adjacent first electrode fingers and the distance between adjacent second electrode fingers are both λ;

[0037] The length of the crossing region between the first electrode finger and the second electrode finger in the interdigitated electrode pair is 5λ to 40λ.

[0038] In some optional embodiments, the thickness of the piezoelectric film is 0.1λ to 1λ.

[0039] In some optional embodiments, the piezoelectric film is rotated Y-cut, and the cutting angle is 0° to 75°.

[0040] In some optional embodiments, the top electrode further includes a first reflection grid and a second reflection grid, and the first reflection grid and the second reflection grid are respectively arranged on both sides of a preset number of interdigital electrode pairs.

[0041] In some optional embodiments, the acoustic wave resonator further includes a bottom electrode, and the bottom electrode is disposed on a second surface of the piezoelectric film, where the second surface is opposite to the first surface.

[0042] In some optional embodiments, the bottom electrode is a surface electrode.

[0043] In some optional embodiments, the bottom electrode is an interdigitated electrode, and the electrode fingers of the bottom electrode correspond one-to-one with the electrode fingers in the top electrode.

[0044] In some optional embodiments, the acoustic wave resonator further includes a supporting substrate, and the piezoelectric film is disposed on the supporting substrate.

[0045] In some optional embodiments, the material of the supporting substrate is one of sapphire, silicon, spinel, silicon carbide, diamond, diamond-like carbon, silicon nitride, boron nitride, boron carbide, quartz, germanium, aluminum nitride, silicon nitride, yttrium aluminum garnet, lithium tantalate, and lithium niobate.

[0046] In some optional embodiments, at least one intermediate dielectric layer is further provided between the piezoelectric film and the supporting substrate.

[0047] In some optional embodiments, the material of the intermediate dielectric layer is at least one of silicon oxide, aluminum oxide, aluminum nitride, silicon nitride, polysilicon, and amorphous silicon.

[0048] In some optional embodiments, a Bragg reflection layer is further provided between the piezoelectric film and the supporting substrate.

[0049] In some optional embodiments, a load structure is provided in the area corresponding to the first electrode fingers and the second gap tracks, and in the area corresponding to the second electrode fingers and the first gap tracks.

[0050] In some optional embodiments, the load structure is at least one of a load block, a load bar, and a widened electrode finger bar.

[0051] On the other hand, an embodiment of the present application provides an acoustic wave filter, which includes at least one acoustic wave resonator as described above.

[0052] In some optional embodiments, the acoustic wave filter includes at least two acoustic wave resonators as described above;

[0053] At least two acoustic wave resonators correspond to at least two preset angles of different sizes.

[0054] In some optional embodiments, the at least two acoustic wave resonators include a series acoustic wave resonator and a parallel acoustic wave resonator;

[0055] The average angle of the first gap track tangent angle and the second gap track tangent angle in the series acoustic wave resonator is greater than the average angle of the first gap track tangent angle and the second gap track tangent angle in the parallel acoustic wave resonator.

[0056] On the other hand, an embodiment of the present application provides an acoustic wave filter module, which includes the acoustic wave filter as described above.

[0057] In some optional embodiments, the acoustic wave filter module includes at least two acoustic wave filters, and the at least two acoustic wave filters are formed on the same piezoelectric film.

[0058] In some optional embodiments, in the acoustic wave filter module, the maximum relative bandwidth of the acoustic wave filter and the minimum relative bandwidth of the acoustic wave filter meet the following conditions: (FBW max -FBW min ) / FBW min ≥10%;

[0059] Among them, FBW max The maximum relative bandwidth of the acoustic wave filter in the acoustic wave filter module, FBW min The minimum relative bandwidth of the acoustic wave filter in the acoustic wave filter module.

[0060] The technical solution provided by the embodiments of the present application has the following technical effects:

[0061] The acoustic wave resonator, acoustic wave filter and acoustic wave filter module described in the embodiments of the present application utilize a single crystal piezoelectric film with in-plane anisotropy, and by designing a preset angle between the interdigitated electrode pair and the preset crystal axis in the piezoelectric film, the direction of acoustic wave propagation in the acoustic wave plane is changed to achieve the adjustment of the electromechanical coupling coefficient of the acoustic wave resonator. Moreover, by designing the first gap track tangent angle and the second gap track tangent angle, while changing the electromechanical coupling coefficient of the acoustic wave resonator, energy leakage caused by excessive energy flow incident angle is avoided. Therefore, acoustic wave resonators with different electromechanical coupling coefficients can be realized on the same piezoelectric film, and then acoustic wave filters with different relative bandwidths can be realized. In addition, by selecting a suitable in-plane acoustic wave propagation direction, the target acoustic wave mode energy flow angle propagating in the acoustic wave resonator is made to have a large gap with the out-of-band parasitic mode energy flow angle, and then combined with a suitable gap track tangent angle, it is possible to achieve the leakage of the out-of-band parasitic mode while maintaining the high quality factor of the target acoustic wave mode, thereby improving the out-of-band suppression level. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0063] FIG1 is a structural schematic diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0064] FIG2 is a structural schematic diagram of a top electrode provided in an embodiment of the present application;

[0065] FIG3 shows the changes of the phase velocity, electromechanical coupling coefficient k2, and energy flow angle τ of an acoustic wave resonator with the acoustic wave propagation direction angle θ;

[0066] FIG4 is a schematic diagram showing how the direction of the acoustic wave energy flow and the tangent direction of the gap trajectory of an acoustic wave resonator change with the angle θ of the acoustic wave propagation direction;

[0067] FIG5 is a schematic diagram showing how the anti-resonance frequency Q value Qp of an acoustic wave resonator changes with the acoustic wave propagation direction angle θ;

[0068] FIG6 is a second structural diagram of a top electrode provided in an embodiment of the present application;

[0069] Figure 7 shows the admittance curves corresponding to Figure 6 when θ = 0° and θ = 20°, where γ is 0°;

[0070] Figure 8 shows the Bode-Q curves for θ = 0° and θ = 20° corresponding to Figure 6 , where γ is 0°;

[0071] Figure 9 shows the main mode vibration shape diagram when θ = 20° corresponding to Figure 6, where γ is 0°;

[0072] FIG10 is a second structural diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0073] FIG11 is a third structural diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0074] FIG12 is a fourth structural diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0075] FIG13 is a fifth structural diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0076] FIG14 is a sixth structural diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0077] FIG15 is a seventh structural diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0078] FIG16 is a third structural diagram of a top electrode provided in an embodiment of the present application;

[0079] FIG17 is a fourth structural diagram of a top electrode provided in an embodiment of the present application;

[0080] FIG18 is a structural schematic diagram eight of an acoustic wave resonator provided in an embodiment of the present application;

[0081] FIG19 is a schematic diagram showing how the direction of the acoustic wave energy flow and the tangent direction of the gap trajectory of an acoustic wave resonator proposed in an embodiment of the present application change with the angle θ of the acoustic wave propagation direction; FIG.

[0082] FIG20 shows the Q value Qp at the anti-resonance frequency corresponding to different gap trajectory tangential angles γ and different sound wave propagation direction angles θ provided in an embodiment of the present application;

[0083] FIG21 shows the electromechanical coupling coefficients k2 and Qp corresponding to different acoustic wave propagation direction angles θ extracted from another set of experimental results provided in an embodiment of the present application;

[0084] FIG22 is an admittance curve of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided by an embodiment of the present application;

[0085] FIG23 is an impedance phase curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided by an embodiment of the present application;

[0086] FIG24 is a Bode-Q curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided in an embodiment of the present application;

[0087] FIG25 is a target acoustic wave mode shape diagram corresponding to FIG17 when the acoustic wave propagation direction angle θ=20° and γ-θ=7°, provided by an embodiment of the present application;

[0088] FIG26 is a graph showing the admittance and conductance of an acoustic wave resonator when the acoustic wave propagation direction angle θ=0° and γ=0°, provided by an embodiment of the present application;

[0089] FIG27 is a graph showing the admittance and conductance of an acoustic wave resonator when the acoustic wave propagation direction angle θ=20° and γ-θ=7°, provided by an embodiment of the present application;

[0090] FIG28 is a schematic diagram showing displacement distributions of transverse high-order modes corresponding to an excessively small energy inflow incident angle η, an appropriate energy inflow incident angle η, and an excessively large energy inflow incident angle η, provided in an embodiment of the present application;

[0091] FIG29 is a first structural diagram corresponding to an acoustic wave filter provided in an embodiment of the present application;

[0092] FIG30 is an admittance curve and a Bode-Q curve of each acoustic wave resonator corresponding to an acoustic wave filter shown in Table 1 provided in an embodiment of the present application;

[0093] FIG31 is an S-parameter curve corresponding to an acoustic wave filter in Table 1 provided in an embodiment of the present application;

[0094] FIG32 is a second structural diagram corresponding to an acoustic wave filter provided in an embodiment of the present application;

[0095] FIG33 is an S21 curve corresponding to an acoustic wave filter shown in Table 1 and Table 2 provided in an embodiment of the present application;

[0096] FIG34 is a schematic structural diagram corresponding to a comparative acoustic wave filter;

[0097] FIG35 is an S-parameter curve corresponding to the acoustic wave filter in Table 3;

[0098] FIG36 is a third structural diagram corresponding to an acoustic wave filter provided in an embodiment of the present application;

[0099] FIG37 is an S-parameter curve corresponding to an acoustic wave filter in Table 4 provided in an embodiment of the present application;

[0100] FIG38 is an S21 curve corresponding to an acoustic wave filter shown in Table 3 and Table 4 provided in an embodiment of the present application;

[0101] FIG39 is a ninth structural diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0102] FIG40 shows the Q value Qp at the anti-resonance frequency corresponding to different gap track tangential angles γ and different sound wave propagation direction angles θ provided in an embodiment of the present application;

[0103] FIG41 is an admittance curve of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=0° and γ=-5°, and the acoustic wave propagation direction angle θ=4° and γ=10°;

[0104] FIG42 is a Bode-Q curve diagram of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=0° and γ=-5°, and the acoustic wave propagation direction angle θ=4° and γ=10°;

[0105] FIG43 is an admittance curve of an acoustic resonator provided by an embodiment of the present application when γ is 0°, the acoustic wave propagation direction angle θ=0°, and the acoustic wave propagation direction angle θ=20°;

[0106] FIG44 is a Bode-Q curve of an acoustic wave resonator provided by an embodiment of the present application when γ is 0°, the acoustic wave propagation direction angle θ=0°, and the acoustic wave propagation direction angle θ=20°;

[0107] FIG45 shows the electromechanical coupling coefficients k2 and Qp corresponding to different acoustic wave propagation direction angles θ extracted from another set of experimental results provided in an embodiment of the present application;

[0108] FIG46 is an admittance curve of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided by an embodiment of the present application;

[0109] FIG47 is an impedance phase curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided by an embodiment of the present application;

[0110] FIG48 is a Bode-Q curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided by an embodiment of the present application;

[0111] FIG49 is a fifth structural diagram corresponding to an acoustic wave filter provided in an embodiment of the present application;

[0112] FIG50 is an S-parameter curve corresponding to an acoustic wave filter shown in Table 5 and Table 6 provided in an embodiment of the present application;

[0113] FIG51 is a structural schematic diagram 10 of an acoustic wave resonator provided in an embodiment of the present application;

[0114] FIG52 shows the variation of the electromechanical coupling coefficient k2, the energy flow angle τ of the target acoustic wave mode and the parasitic mode with the acoustic wave propagation direction angle θ of an acoustic wave resonator provided by an embodiment of the present application;

[0115] FIG53 is an admittance curve of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ is 157°, γ = 0° and γ = -20°;

[0116] Figure 54 is an impedance phase curve diagram of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ is 157°, γ = 0° and γ = -20°.

[0117] The following is a supplementary explanation of the accompanying drawings: 10-top electrode; 110-first finger electrode; 111-first electrode finger; 112-first dummy electrode; 113-first bus bar; 120-second finger electrode; 121-second electrode finger; 122-second dummy electrode; 123-second bus bar; 130-reflection grid; 131-first reflection grid; 132-second reflection grid; 20-piezoelectric film; 30-bottom electrode; 40-support substrate; 50-intermediate dielectric layer; 51-first intermediate dielectric layer; 52-second intermediate dielectric layer; 60-Bragg reflection layer; 70-load structure; 71-load block; 72-load bar. DETAILED DESCRIPTION

[0118] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0119] It should be noted that the "one embodiment" or "embodiment" referred to in the description of the embodiments of the present application refers to specific features, structures, or characteristics that may be included in at least one implementation of the present application. It should be understood that in the description and claims of the embodiments of the present application and the accompanying drawings, the terms "upper," "lower," "top," "bottom," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the drawings and are intended solely for ease of description and simplification of the present application. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present application. The terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance or to implicitly specify the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. Furthermore, the terms "first," "second," etc. are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential sequence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, in the description of this embodiment, unless otherwise specified, "plurality" means two or more. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system or product that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, products or devices.

[0120] In order to make the purpose, technical solutions and advantages disclosed in the embodiments of the present application more clearly understood, the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present application and are not intended to limit the embodiments of the present application.

[0121] In response to the problem that a single material system is difficult to be compatible with frequency bands of different relative bandwidths, the embodiments of the present application propose an acoustic wave resonator, an acoustic wave filter and an acoustic wave filter module, by adopting a single crystal piezoelectric film with in-plane anisotropy, changing the direction of acoustic wave propagation in the acoustic wave plane to adjust the electromechanical coupling coefficient of the acoustic wave resonator. By adopting a suitable gap track tangent, while changing the electromechanical coupling coefficient of the acoustic wave resonator, energy leakage caused by excessive energy flow incident angle is avoided. Therefore, acoustic wave resonators with different electromechanical coupling coefficients can be realized on the same piezoelectric film, and then acoustic wave filters with different relative bandwidths can be realized, thereby greatly saving the production cost of materials and improving the integration of acoustic wave filters. In addition, the electromechanical coupling coefficient of the target acoustic wave mode is adjusted by changing the in-plane acoustic wave propagation direction, and by matching the angle between the suitable gap track and the energy flow direction, the radiation of the acoustic wave to the bus bar is avoided, maintaining a high quality factor (Q value).

[0122] Please refer to FIG. 1 , which is a structural diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in FIG. 1 , the acoustic wave resonator includes a piezoelectric film 20 and a top electrode 10 disposed on a first surface of the piezoelectric film 20 .

[0123] In the embodiment of the present application, the top electrode 10 is an interdigitated electrode. FIG2 is a structural schematic diagram of a top electrode provided in the embodiment of the present application. As shown in FIG2 , the top electrode 10 includes a first finger electrode 110 and a second finger electrode 120 .

[0124] As shown in Figure 2, the first finger electrode 110 includes a preset number of first electrode fingers 111 and first dummy electrodes 112. The roots of the first electrode fingers 111 and the first dummy electrodes 112 are both connected to the first bus bar 113, and the first electrode fingers 111 and the first dummy electrodes 112 are spaced apart from each other. Optionally, in the first finger electrode 110, the number of first electrode fingers 111 and the number of first dummy electrodes 112 can be the same or different, for example, the number of first electrode fingers 111 can be one more than the number of first dummy electrodes 112, or the number of first electrode fingers 111 can be one less than the number of first dummy electrodes 112. In the first finger electrode 110, the arrangement period of the first electrode fingers 111 is λ. That is, the spacing between two adjacent first electrode fingers 111 is λ. Similarly, the spacing between two adjacent first dummy electrodes 112 is also λ.

[0125] As shown in FIG2 , the second finger electrode 120 includes a preset number of second electrode fingers 121 and second dummy electrodes 122. The roots of the second electrode fingers 121 and the second dummy electrodes 122 are both connected to the second bus bar 123, and the second electrode fingers 121 and the second dummy electrodes 122 are spaced apart from each other. Optionally, in the second finger electrode 120, the number of second electrode fingers 121 and the number of second dummy electrodes 122 may be the same or different, for example, the number of second electrode fingers 121 may be one more than the number of second dummy electrodes 122, or the number of second electrode fingers 121 may be one less than the number of second dummy electrodes 122. Furthermore, the number of second electrode fingers 121 and the number of first electrode fingers 111 may be the same or different, for example, the number of second electrode fingers 121 may be one more than the number of first electrode fingers 111, or the number of second electrode fingers 121 may be one less than the number of first electrode fingers 111. In the second finger electrode 120, the second electrode fingers 121 are arranged at a period of λ. That is, the distance between two adjacent second electrode fingers 121 is λ. Similarly, the distance between two adjacent second dummy electrodes 122 is also λ.

[0126] As shown in Figure 2, there is an overlapping area between the first finger electrode 110 and the second finger electrode 120 on the plane. In the overlapping area, the first electrode finger 111 and the second electrode finger 121 are arranged crosswise. That is, in the overlapping area, for the first electrode finger 111 not on the outside, its two sides are the second electrode finger 121, and similarly, for the second electrode finger 121 not on the outside, its two sides are the first electrode finger 111. For an adjacent pair of first electrode fingers 111 and second electrode fingers 121, the two constitute an interdigitated electrode pair. Optionally, the length of the intersection area between the first electrode finger 111 and the second electrode finger 121 in the interdigitated electrode pair is 5λ to 40λ, that is, the width of the overlapping area is 5λ to 40λ.

[0127] In the top electrode 10, the first electrode fingers 111 are arranged opposite the second dummy electrodes 122, and the second electrode fingers 121 are arranged opposite the first dummy electrodes 112. That is, in the top electrode 10, each first electrode finger 111 corresponds to a second dummy electrode 122, and similarly, each second electrode finger 121 corresponds to a first dummy electrode 112. For any corresponding pair of first electrode fingers 111 and second dummy electrodes 122, they do not touch each other, i.e., there is a gap between them. Fitting the gaps between all corresponding first electrode fingers 111 and second dummy electrodes 122 with a smooth curve yields a curve, which can be referred to as the first gap trajectory. Similarly, for any corresponding pair of second electrode fingers 121 and first dummy electrodes 112, they do not touch each other, i.e., there is a gap between them. Fitting the gaps between all corresponding second electrode fingers 121 and first dummy electrodes 112 with a smooth curve yields a curve, which can be referred to as the second gap trajectory.

[0128] For the acoustic wave resonator, the acoustic wave propagation direction corresponding to the target acoustic wave mode that transmits the acoustic wave in its piezoelectric film 20 is perpendicular to the extension direction of the interdigital electrode pair. In other words, the acoustic wave propagation direction is perpendicular to the axial direction of the first electrode finger 111 or the second electrode finger 121, or the acoustic wave propagation direction is parallel to the normal direction of the interdigital pair. The angle between the direction of the acoustic wave energy flow and the direction of the acoustic wave propagation in the acoustic wave resonator is the energy flow angle. In the acoustic wave resonator, the direction of the acoustic wave energy flow is the group velocity direction. Referring to Figure 2, the preset crystal axis in the piezoelectric film 20 is the first reference axis, the normal direction of the interdigital electrode pair is the second reference axis, and the direction of the acoustic wave energy flow is the third reference axis. The preset angle between the first reference axis and the second reference axis is the acoustic wave propagation direction angle θ.

[0129] In an acoustic wave resonator, the angle between the gap track and the direction of acoustic wave propagation is the gap track tangent angle γ. When the gap track is a curve, the angle between the tangent of the gap track and the direction of acoustic wave propagation can be used as the gap track tangent angle. Referring to Figure 2, the angle between the average tangent of the first gap track and the second reference axis is the first gap track tangent angle The angle between the average tangent of the second gap track and the second reference axis is the second gap track tangent angle The average tangent of the first gap trajectory refers to the average angle obtained by averaging the angles between the tangent of the first gap trajectory at each second pseudo-finger electrode 122 and the second reference axis, and the straight line obtained by rotating the second reference axis counterclockwise around the average angle is the average tangent of the first gap trajectory. The average tangent of the second gap trajectory refers to the average angle obtained by averaging the angles between the tangent of the second gap trajectory at each first pseudo-finger electrode 112 and the second reference axis, and the straight line obtained by rotating the second reference axis counterclockwise around the average angle is the average tangent of the second gap trajectory. In other words, the average tangent of the first gap trajectory is a straight line determined by the average angle of all tangent direction angles on the first gap trajectory. The average tangent of the second gap trajectory is a straight line determined by the average angle of all tangent direction angles on the second gap trajectory.

[0130] In addition, referring to FIG2 , in the acoustic resonator, the angle between the gap trajectory and the direction of the acoustic wave energy flow is the energy flow incident angle η. The angle between the second reference axis and the third reference axis is the energy flow angle τ. The angle between the first reference axis and the second reference axis is expressed as the acoustic wave propagation direction angle θ, and the energy flow angle τ = arctan (1 / νp×dνp / d acoustic wave propagation direction angle θ), where νp is the phase velocity corresponding to different acoustic wave propagation directions. Since the positive direction of the energy flow angle is related to the orientation of the crystal axis, it is sometimes clockwise and sometimes counterclockwise. The gap trajectory tangential angle γ is always counterclockwise, so for the convenience of calculation, the positive direction of the energy flow angle and the reference positive direction of the gap trajectory tangential angle can be unified into the same direction, thereby obtaining the reference energy flow angle τ'. The reference energy flow angle τ' has the same absolute value as the energy flow angle τ.

[0131] For acoustic wave resonators, the acoustic wave propagation directions with energy flow angles of 0 corresponding to different target acoustic wave modes are different. Figure 3 shows the changes in the phase velocity, electromechanical coupling coefficient k2, and energy flow angle τ of an acoustic wave resonator with the acoustic wave propagation direction angle θ. As shown in Figure 3, when the acoustic wave propagation direction angle θ = 0°, the phase velocity and electromechanical coupling coefficient reach the maximum, and the energy flow angle is 0°. When the acoustic wave propagation direction deviates from the crystal X-axis, the electromechanical coupling coefficient decreases. This shows that the electromechanical coupling coefficient can be adjusted by changing the acoustic wave propagation direction. However, when the acoustic wave propagation direction angle θ≠0°, the energy flow angle τ is often not 0. When the angle between the energy flow direction and the waveguide boundary composed of gaps is too large, it will cause the leakage of acoustic wave energy, which will then cause the Q value of the acoustic wave resonator to decrease.

[0132] Figure 4 is a schematic diagram of the direction of the acoustic wave energy flow and the tangent of the gap trajectory of an acoustic wave resonator changing with the angle of the acoustic wave propagation direction θ. As shown in Figure 4, when the angle of the acoustic wave propagation direction θ≠0°, a large angle may appear between the direction of the acoustic wave energy flow and the tangent of the gap trajectory. Figure 5 is a schematic diagram of the anti-resonance frequency Q value Qp of an acoustic wave resonator changing with the angle of the acoustic wave propagation direction θ. As shown in Figure 5, when the angle of the acoustic wave propagation direction θ increases from 0° to 4°, Qp increases. This is because the transverse high-order modes near the anti-resonance frequency are suppressed, and a variety of existing methods for suppressing transverse high-order modes can achieve this effect. When the angle of the acoustic wave propagation direction θ is greater than 5°, Qp begins to drop sharply. This is because the angle between the direction of the acoustic wave energy flow and the tangent of the gap trajectory is too large, that is, the energy flow incident angle η is too large. Therefore, simply using the method of changing the in-plane orientation to adjust the electromechanical coupling coefficient will inevitably lead to the problem of a sharp drop in the Q value due to the excessive energy flow incident angle. Figure 7 shows the admittance curves for θ = 0° and θ = 20° corresponding to Figure 6, where γ is 0°. Figure 8 shows the Bode-Q curves for θ = 0° and θ = 20° corresponding to Figure 6, where γ is 0°. As can be seen from the figure, although the purpose of adjusting the electromechanical coupling coefficient is achieved when θ = 20° compared to θ = 0°, the Q value decreases significantly. Figure 9 shows the main mode vibration shape diagram for θ = 20° corresponding to Figure 6, where γ is 0°. As shown in Figure 9, it can be seen that since the tangent angle η between the energy flow direction and the air gap trajectory reaches 20° at this time, a large amount of acoustic wave energy leaks into the busbar area, which is the main reason for the decrease in Q value.

[0133] In the embodiment of the present application, because the piezoelectric film 20 has in-plane anisotropy, different in-plane directions correspond to different electromechanical coupling coefficients. Therefore, by changing the in-plane propagation direction of the acoustic wave, acoustic resonators with different electromechanical coupling coefficients can be realized on the same piezoelectric film 20.

[0134] Specifically, the piezoelectric film 20 in the embodiment of the present application can be a single crystal piezoelectric material with in-plane anisotropy. Optionally, the material of the piezoelectric film 20 can be any one of piezoelectric materials such as lithium niobate, lithium tantalate, potassium niobate, etc. Optionally, the thickness of the piezoelectric film 20 is 0.1λ to 1λ. Optionally, the cut type of the piezoelectric film is a rotated Y cut, and the cut angle can be 0° to 75°. By utilizing the in-plane anisotropy in the piezoelectric film 20, by designing the angle of the preset angle, that is, changing the angle between the sound wave propagation direction and the in-plane crystal axis direction of the piezoelectric film 20, the sound wave propagation direction angle θ, the electromechanical coupling coefficient of the acoustic resonator can be regulated.

[0135] In the embodiment of the present application, the electromechanical coupling coefficient of the target acoustic wave mode in the acoustic wave resonator satisfies the following conditions: (k2 max -k2 30° ) / k2 max ≥30%. Among them, k2max is the maximum value of the electromechanical coupling coefficient when the sound wave propagates in different directions, k2 30° is the electromechanical coupling coefficient after the crystal axis orientation is rotated by 30° relative to the maximum electromechanical coupling value. Optionally, the target acoustic wave mode can be a 0th order horizontal shear mode, a 0th order longitudinal leakage surface acoustic wave mode, a 0th order Rayleigh mode, etc.

[0136] As an optional embodiment, the piezoelectric film 20 is an X-cut lithium niobate or lithium tantalate, the target acoustic wave mode in the acoustic wave resonator is a 0th order horizontal shear mode, and the preset crystal axis is the Y-axis. The preset angle is 0° to 45°, or 130° to 180°. That is, when the piezoelectric film 20 is an X-cut lithium niobate or lithium tantalate, and the target acoustic wave mode is a 0th order horizontal shear mode, if it is stipulated that when the acoustic wave propagates along the Y-axis of the crystal, the acoustic wave propagation direction angle θ=0°, and when the acoustic wave propagates along the Z-axis of the crystal, the acoustic wave propagation direction angle θ=90°, then the acoustic wave propagation direction angle is 0°≤acoustic wave propagation direction angle θ<45° or 130°<acoustic wave propagation direction angle θ≤180°.

[0137] As another optional embodiment, the piezoelectric film 20 is a rotated Y-cut lithium niobate or lithium tantalate, the target acoustic wave mode in the acoustic wave resonator is a 0th order horizontal shear mode, and the preset crystal axis is the X-axis. The preset angle is -40° to 40°. That is, when the piezoelectric film 20 is lithium niobate or lithium tantalate, the cut is a rotated Y-cut, and the target acoustic wave mode is a 0th order horizontal shear mode, if it is stipulated that when the acoustic wave propagates along the crystal X-axis, the acoustic wave propagation direction angle θ = 0°, then the acoustic wave propagation direction range is -40° < acoustic wave propagation direction angle θ < 40°.

[0138] In some embodiments, the sound wave propagation direction angle may not be 0, that is, the sound wave propagation direction angle θ≠0°.

[0139] In the acoustic wave resonator, the angle between the tangent direction of the gap track and the direction of acoustic wave propagation is γ, and the angle between the tangent direction of the gap track and the direction of acoustic wave energy flow of the target acoustic wave mode is the energy flow incident angle η = γ-τ'. Therefore, the tangent direction of the gap track will directly affect the size of the energy flow incident angle. If the energy flow incident angle is too large, energy leakage will occur, thereby reducing the quality factor of the acoustic wave resonator. Therefore, in order to avoid this situation, it is necessary to design the tangent direction of the first gap track and the tangent direction of the second gap track. In other words, the tangent angle of the first gap track and the tangent angle of the second gap track need to meet the preset conditions.

[0140] In the embodiment of the present application, the direction of the acoustic wave energy flow of the acoustic wave resonator is taken as the third reference axis, and the angle between the second reference axis and the third reference axis is taken as the reference energy flow angle;

[0141] The tangential angle of the first gap trajectory meets the following preset conditions:

[0142] in, is the tangential angle of the first gap trajectory, and τ' is the reference energy flow angle; optionally, the reference energy flow angle is not equal to 0.

[0143] The tangential angle of the second gap trajectory meets the following preset conditions:

[0144] in, is the tangential angle of the second gap trajectory, τ' is the reference energy flow angle, and optionally, the reference energy flow angle is not equal to 0.

[0145] In an embodiment of the present application, the angle between the tangent direction of the first gap track at any first electrode finger and the third reference axis is the first energy flow incident angle, and the angle between the tangent direction of the second gap track at any second electrode finger and the third reference axis is the second energy flow incident angle, and the maximum value of at least one first energy flow incident angle or the maximum value of at least one second energy flow incident angle is greater than or equal to 1°.

[0146] In the embodiment of the present application, in order to make the above-mentioned tangential angle of the gap track meet the conditions, it can be achieved by setting the length of the first pseudo-finger electrode 112 and the length of the second pseudo-finger electrode 122. Specifically, the angle between the average tangent of the first gap track and the direction of sound wave propagation is 1, the angle between the average tangent of the second gap track and the direction of sound wave propagation is 2, N is the number of forked electrode pairs, γi is the angle between the tangent direction of the gap track at the i-th pair of forked electrodes and the direction of sound wave propagation, then γ1i is the angle between the tangent direction of the first gap track at the i-th pair of forked electrodes and the direction of sound wave propagation, γ2i is the angle between the tangent direction of the second gap track at the i-th pair of forked electrodes and the direction of sound wave propagation. The pseudo-finger electrode adjacent to the second air gap is the first pseudo-finger electrode 112, the length of the first pseudo-finger electrode 112 at the i-th pair of forked electrodes is L1i, and the angle between the tangent direction of the second gap track at the i-th pair of forked electrodes and the direction of sound wave energy flow is the energy flow incident angle η1i=|γ 2i -τ'|, the pseudo-finger electrode adjacent to the first air gap is the second pseudo-finger electrode 122, the length of the second pseudo-finger electrode 122 at the i-th pair of interdigital electrodes is L2i, and the angle between the tangent direction of the first gap trajectory at the i-th pair of interdigital electrodes and the direction of the acoustic wave energy flow is the energy flow incident angle η2i=|γ 1i -τ'|.

[0147] Specifically, the length of the first dummy electrode 112 satisfies the following conditions: 1i ≥5λ×tan(|γ 2i -τ'|),

[0148] Among them, L 1i is the length of the i-th first dummy electrode 112 in the first finger electrode 110, γ2i is the angle between the tangent line of the second gap track at the i-th first dummy electrode 112 and the second reference axis, and τ' is the reference energy flux angle.

[0149] Specifically, the length of the second dummy electrode 122 satisfies the following conditions: 2i ≥5λ×tan(|γ 1i -τ'|);

[0150] Among them, L 2i is the length of the i-th second dummy electrode 112 in the second finger electrode 110, γ 1i is the angle between the tangent line of the first gap track at the i-th second dummy electrode 122 and the second reference axis, and τ' is the reference energy flow angle.

[0151] Within a certain range, the longer the length of the dummy electrode, the less acoustic wave leakage. Therefore, in some embodiments, the length of the first dummy electrode 112 at the i-th pair of interdigital electrodes may also satisfy the following condition: L1i≥10λ×tan(|γ 2i -τ'|), and the length of the second dummy electrode 122 at the i-th pair of interdigital electrodes may also satisfy the following condition L2i≥10λ×tan(|γ 1i -τ'|), where τ'≠0. Of course, the longer the length of the dummy electrode, the greater the resistance will be, thereby increasing the power consumption of the device. Therefore, the length of the dummy electrode should not be too long.

[0152] In the embodiment of the present application, the first gap track can be a straight line or a curve. Similarly, the second gap track can be a straight line or a curve. When the first gap track is a straight line, the average tangent direction of the first gap track is the same as the tangent direction of the gap track at the i-th pair of interdigital electrodes, that is, When the second gap track is a straight line, the average tangent direction of the second gap track is the same as the tangent direction of the gap track at the i-th pair of interdigital electrodes, that is, In some embodiments, the first gap track is parallel to the second gap track. That is, the tangent direction of the first gap track is the same as the tangent direction of the second gap track and remains constant, that is, FIG6 is a second structural schematic diagram of a top electrode provided in an embodiment of the present application. As shown in FIG6 , the tangential direction of the first gap track and the second gap track are the same, and the first gap track and the second gap track are parallel.

[0153] In the embodiments of the present application, by adopting a suitable tangent direction for the gap track, the energy flow direction and the tangent direction of the gap track do not completely coincide, thereby suppressing the transverse high-order modes in the acoustic resonator. In addition, due to the difference in energy flow direction between the target acoustic wave mode and the parasitic mode, the target acoustic wave mode can be made to have a smaller energy flow incident angle, while the parasitic mode has a larger energy flow incident angle, thereby suppressing the out-of-band parasitic mode. Compared with directly adopting a large tilt angle to suppress high-frequency parasitic modes, it can ensure that the Q value of the target acoustic wave mode does not drop excessively.

[0154] In an embodiment of the present application, the top electrode 10 further includes a reflective grid 130, which is used to reflect sound waves, thereby preventing the sound waves from leaking to areas outside the interdigital electrodes. The reflective grid 130 includes a reflective grid 130 electrode and a reflective grid 130 bus bar, and the extension direction of the reflective grid 130 electrode has a preset angle with the propagation direction of the sound wave. In some embodiments, the extension direction of the reflective grid 130 electrode can be perpendicular to the propagation direction of the sound wave. As shown in Figure 2, the top electrode 10 further includes a first reflective grid 131 and a second reflective grid 132. The first reflective grid 131 and the second reflective grid 132 are respectively arranged on both sides of a preset number of interdigital electrode pairs, that is, on both sides of the first finger electrode 110 and the second finger electrode 120.

[0155] In some optional embodiments, the acoustic wave resonator further includes a bottom electrode 30. The bottom electrode 30 is disposed on the second surface of the piezoelectric film 20, where the second surface is opposite to the first surface. The first surface of the piezoelectric film 20 may be the upper surface of the piezoelectric film 20, and the first surface may be the lower surface of the piezoelectric film 20. Optionally, the bottom electrode 30 may be a block electrode, a surface electrode, an interdigitated electrode, or the like.

[0156] As an optional embodiment, the bottom electrode 30 is a surface electrode. Figure 10 is a second schematic structural diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in Figure 10, the acoustic wave resonator includes a bottom electrode 30, a piezoelectric film 20, and a top electrode 10, arranged in order from bottom to top. The bottom electrode 30 can be a surface electrode.

[0157] As another optional embodiment, the bottom electrode 30 is an interdigitated electrode. Figure 11 is a third schematic structural diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in Figure 11, the acoustic wave resonator includes a bottom electrode 30, a piezoelectric film 20, and a top electrode 10, arranged in order from bottom to top. The bottom electrode 30 can be an interdigitated electrode. The electrode fingers of the bottom electrode 30 correspond one-to-one with the electrode fingers of the top electrode 10.

[0158] In other optional embodiments, the acoustic wave resonator further includes a supporting substrate 40, and the piezoelectric film 20 is disposed on the supporting substrate 40. Optionally, the material of the supporting substrate 40 is one of sapphire, silicon, spinel, silicon carbide, diamond, diamond-like carbon, silicon nitride, boron nitride, boron carbide, quartz, germanium, aluminum nitride, silicon nitride, yttrium aluminum garnet, lithium tantalate, and lithium niobate. As an example, the piezoelectric film 20 is lithium tantalate or lithium niobate, and the supporting substrate 40 is silicon, sapphire, quartz or silicon carbide. As another example, Figure 12 is a fourth structural schematic diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in Figure 12, the acoustic wave resonator includes a supporting substrate 40, a bottom electrode 30, a piezoelectric film 20, and a top electrode 10 arranged in sequence from bottom to top, wherein the bottom electrode 30 can be a surface electrode.

[0159] In other optional embodiments, at least one intermediate dielectric layer 50 is further provided between the piezoelectric film 20 and the supporting substrate 40. FIG13 is a fifth structural schematic diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in FIG13 , the acoustic wave resonator includes a supporting substrate 40, an intermediate dielectric layer 50, a bottom electrode 30, a piezoelectric film 20, and a top electrode 10, which are arranged in sequence from bottom to top. Among them, the bottom electrode 30 can be an interdigitated electrode. The function of the intermediate dielectric layer 50 can be to accelerate the heat dissipation of the acoustic wave resonator, to reduce the power consumption of the acoustic wave resonator, or to perform temperature compensation for radio frequency signals. The number of layers of the intermediate dielectric layer 50 can be one layer or multiple layers. Optionally, the functions of different intermediate dielectric layers 50 can be different. Optionally, the material of the intermediate dielectric layer 50 can be at least one of silicon oxide, aluminum oxide, aluminum nitride, silicon nitride, polycrystalline silicon, and amorphous silicon. As an example, the piezoelectric film 20 is made of lithium tantalate or lithium niobate, the intermediate dielectric layer 50 is made of silicon oxide, and the supporting substrate 40 is made of sapphire, quartz, or silicon carbide. As another example, the piezoelectric film 20 is made of lithium tantalate or lithium niobate, the intermediate dielectric layer 50 is made of silicon oxide or polycrystalline silicon, and the supporting substrate 40 is silicon.

[0160] In the above embodiment, the acoustic wave resonator may also not include the supporting substrate 40, that is, the piezoelectric film 20 is directly disposed on the intermediate dielectric layer 50. FIG14 is a sixth structural schematic diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in FIG14 , the acoustic wave resonator includes an intermediate dielectric layer 50, a piezoelectric film 20, and a top electrode 10, which are sequentially disposed from bottom to top.

[0161] In some other optional embodiments, a Bragg reflector layer 60 may be further provided between the piezoelectric film 20 and the supporting substrate 40. FIG15 is a seventh structural diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in FIG15 , the acoustic wave resonator includes a supporting substrate 40, a Bragg reflector layer 60, a piezoelectric film 20, and a top electrode 10, which are sequentially provided from bottom to top.

[0162] In the embodiment of the present application, a load structure 70 is provided in the area corresponding to the second gap track of the first electrode finger 111 and the area corresponding to the first gap track of the second electrode finger 121. Optionally, the load structure 70 can be provided on the piezoelectric film 20 or on the electrode finger. The load structure 70 is used to reduce the speed of sound in the gap area, making it easier for the sound wave to enter the pseudo-finger electrode area, so that the required energy flow incident angle can be smaller. Optionally, the load structure 70 is at least one of a carrier block, a load bar 72, and a widened electrode finger.

[0163] As an optional embodiment, FIG16 is a third structural schematic diagram of a top electrode provided in an embodiment of the present application. As shown in FIG16 , in the acoustic wave resonator, a load block 71 is provided in the air gap region. The load block 71 is provided in the region corresponding to the first electrode finger 111 and the second gap track, and in the region corresponding to the second electrode finger 121 and the first gap track. Optionally, the load block 71 can be provided on the piezoelectric film 20, or on the first electrode finger 111 and / or the second electrode finger 121, or integrally provided with the first electrode finger 111 and / or the second electrode finger 121. The added load block 71 can reduce the speed of sound in the air gap region, making it easier for the acoustic wave energy to enter the pseudo-finger electrode region, which is beneficial to the suppression of the lateral mode.

[0164] As another optional embodiment, FIG17 is a fourth structural schematic diagram of a top electrode provided in an embodiment of the present application. As shown in FIG17 , in the acoustic wave resonator, a load bar 72 is provided in the air gap region. The load block 71 is provided in the region corresponding to the first gap track and the region corresponding to the second gap track. Optionally, the load block 71 can be provided on the piezoelectric film 20, or on the first electrode finger 111 and / or the second electrode finger 121, or integrally provided with the first electrode finger 111 and / or the second electrode finger 121. The added load bar 72 can reduce the speed of sound in the air gap region, making it easier for the acoustic wave energy to enter the pseudo-finger electrode region, which is beneficial to the suppression of the lateral mode.

[0165] The acoustic wave resonator described in the embodiment of the present application comprises at least a piezoelectric film 20 and a top electrode 10. The top electrode 10 comprises a pair of interdigitated electrodes, a pseudo-finger electrode, and an air gap. The electromechanical coupling coefficient of the piezoelectric film 20 has strong in-plane anisotropy, which means that the electromechanical coupling coefficient can be adjusted by changing the in-plane acoustic wave propagation direction. However, in this process, the energy flow angle is inevitably not zero. Therefore, it is stipulated that the average angle between the tangent direction of the gap trajectory and the direction of the acoustic wave energy flow does not exceed 15°, and the maximum angle is not less than 1°.

[0166] The acoustic resonator described in the embodiment of the present application utilizes the in-plane anisotropy of a single crystal piezoelectric material to adjust the electromechanical coupling coefficient. To achieve this, it is only necessary to change the in-plane direction of the electrode without adding an additional dielectric layer, which greatly reduces the processing cost. In addition, as the in-plane acoustic wave propagation direction changes, the excessive angle between the energy flow direction and the waveguide boundary determined by the air gap will cause the acoustic wave energy to leak to the busbar, thereby causing the device Q value to decrease. Therefore, a limit is placed on the angle between the air gap trajectory and the energy flow direction. The angle between the energy flow direction at the i-th pair of interdigitated electrodes and the tangent direction of the gap trajectory, that is, the energy flow incident angle at the i-th pair of interdigitated electrodes, is specified to be not less than 1°, which can suppress the lateral high-order mode. In addition, as the energy flow angle increases, the corresponding angle between the tangent direction of the optimal gap trajectory and the acoustic wave propagation direction increases, which also has an inhibitory effect on the parasitic mode outside the band, and this inhibitory effect is based on the premise of not sacrificing the target acoustic wave mode Q value. The solution proposed in the embodiment of the present application can meet the requirements of different frequency band bandwidths under a single material system. It can also be used in multi-zero design to achieve a flatter passband and suppress in-band and out-of-band parasitic modes.

[0167] An embodiment of the present application further provides an acoustic wave filter, which includes at least one acoustic wave resonator as described above.

[0168] In the embodiment of the present application, the acoustic wave filter can be obtained by connecting a plurality of acoustic wave resonators in series and / or in parallel. Among the acoustic wave resonators constituting the acoustic wave filter, at least one acoustic wave resonator is the acoustic wave resonator proposed in the above embodiment.

[0169] In some optional embodiments, the acoustic wave filter may include two or more of the acoustic wave resonators proposed in the above embodiments, and the acoustic wave resonators proposed in the two or more above embodiments may correspond to at least two or more preset angles of different sizes. That is, the acoustic wave propagation direction angle θ in at least one acoustic wave resonator is different from the acoustic wave propagation direction angle θ in other acoustic wave resonators. In other embodiments, the acoustic wave propagation direction angle θ of all acoustic wave resonators proposed in two or more above embodiments is different from each other.

[0170] In some optional embodiments, the acoustic wave resonators proposed in two or more of the above embodiments include a series acoustic wave resonator and a parallel acoustic wave resonator. The average angle of the tangential angle of the first gap track and the average angle of the tangential angle of the second gap track in the series acoustic wave resonator is greater than the average angle of the tangential angle of the first gap track and the average angle of the tangential angle of the second gap track in the parallel acoustic wave resonator. In other words, the series acoustic wave resonator Greater than the parallel acoustic resonator This is because a larger angle can suppress the longitudinal high-order modes. However, the longitudinal high-order modes to the left of the resonance frequency of the series acoustic wave resonator may appear within the passband of the acoustic wave filter.

[0171] In the acoustic wave filter described in the embodiment of the present application, in the embodiment of the present application, the relative bandwidth FBW (bandwidth / center frequency) of the acoustic wave filter is proportional to the electromechanical coupling coefficient of the acoustic wave resonator constituting the acoustic wave filter. Since the piezoelectric film 20 has anisotropy in the plane, the electromechanical coupling coefficients corresponding to different in-plane directions are different, so different electromechanical coupling coefficients can be selected by changing the in-plane acoustic wave propagation direction. That is, by designing the acoustic wave propagation direction angle θ of each acoustic wave resonator in the acoustic wave filter, flexible regulation of the electromechanical coupling coefficient can be achieved. Through flexible electromechanical coupling coefficient regulation, the acoustic wave resonators constituting the acoustic wave filter have different electromechanical coupling coefficients, which facilitates multi-zero point design and makes the acoustic wave filter have a flatter passband.

[0172] An embodiment of the present application also provides an acoustic wave filter module, which includes the acoustic wave filter as described above.

[0173] In the embodiment of the present application, the acoustic wave filter module can be obtained by combining two or more of the above-mentioned acoustic wave filters, wherein the two or more acoustic wave filters can be formed on the same piezoelectric film 20 .

[0174] In the embodiment of the present application, the relative bandwidth of each acoustic wave filter in the acoustic wave filter module is FBW. For each acoustic wave filter constituting the acoustic wave filter module, the maximum relative bandwidth of the acoustic wave filter and the minimum relative bandwidth of the acoustic wave filter meet the following conditions: (FBW max -FBW min ) / FBW min ≥10%. Among them, FBW max The maximum relative bandwidth of the acoustic wave filter in the acoustic wave filter module, FBW min The minimum relative bandwidth of the acoustic wave filter in the acoustic wave filter module.

[0175] Based on the above description, the acoustic wave resonator, acoustic wave filter, and acoustic wave filter module provided by the present application are further explained below in combination with some specific embodiments.

[0176] Example 1:

[0177] FIG18 is a schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application. As shown in FIG18 , the acoustic wave resonator in this embodiment includes, from bottom to top, a supporting substrate 40, an intermediate dielectric layer 50, a piezoelectric film 20, and a top electrode 10. The supporting substrate 40 is made of sapphire, the intermediate dielectric layer 50 is made of silicon oxide, and the thickness of the intermediate dielectric layer 50 is 500 nm. The piezoelectric film 20 is made of Y42-cut lithium tantalate and has a thickness of 560 nm. The top electrode 10 is made of titanium / aluminum / titanium, with thicknesses of 2 nm / 120 nm / 3 nm, respectively. The first reference axis is the crystal X-axis.

[0178] As shown in FIG2 or FIG6, the top electrode 10 includes a first bus bar 113, a second bus bar 123, a plurality of interdigitated electrode pairs, a reflector 130, and a dummy electrode. Among them, in the interdigitated electrode pair, the gap between the end of the electrode finger and the dummy electrode is an air gap. The gap between the end of the first electrode finger 111 and the second dummy electrode 122 is the first gap, and the gap between the end of the second electrode finger 121 and the first dummy electrode 112 is the second gap. The angle between the average tangent direction of the first gap trajectory and the direction of the acoustic wave energy flow is the first average energy flow incident angle The angle between the average tangent direction of the second gap trajectory and the direction of the acoustic energy flow is the second average energy flow incident angle and The absolute value of does not exceed 15° to ensure that the acoustic wave energy does not leak into the bus bar in large quantities, so that the acoustic wave resonator always maintains a high Q value during the adjustment of the electromechanical coupling coefficient.

[0179] Figure 19 is a schematic diagram of the changes in the direction of the acoustic wave energy flow and the tangent of the gap trajectory of a proposed acoustic wave resonator provided in an embodiment of the present application as the angle θ of the acoustic wave propagation direction changes. As shown in Figure 19, no matter what value the angle θ of the acoustic wave propagation direction takes, the angle between the direction of the acoustic wave energy flow and the tangent of the gap trajectory is maintained within 15°.

[0180] FIG20 shows the Q value Qp at the antiresonance frequency corresponding to different gap trajectory tangential angles γ and different acoustic wave propagation direction angles θ corresponding to FIG6 provided by an embodiment of the present application. As shown in FIG20, it can be seen from the figure that when γ-θ is around 7° or γ-θ is around -6°, the Q value of the acoustic wave resonator remains above 3000, and even exceeds 5000 at the highest. This is because, according to the results shown in FIG4, when γ-θ is around 7° or γ-θ is around -6°, the energy inflow incident angle η is small, and a small amount of energy leaks into the dummy electrode, so that the lateral high-order mode near the antiresonance frequency is suppressed. At the same time, the energy incident angle η is not large enough to cause the target acoustic wave mode to leak into the busbar, so the Q value is relatively high. When γ-θ is far away from 7° or -6°, the Q value may be lower than 1000. This is because the energy inflow incident angle η is too large or too small at this time.

[0181] FIG21 shows the electromechanical coupling coefficients k2 and Qp corresponding to different acoustic wave propagation direction angles θ extracted from another set of experimental results provided by an embodiment of the present application. As shown in FIG21 , it can be seen that when γ-θ = 6° or γ-θ = 7°, the Q value of the acoustic wave resonator remains above 3500, and the highest exceeds 5000. In particular, when the acoustic wave propagation direction angle θ is greater than 10°, the effect of γ-θ = 6° or γ-θ = 7° on improving the Q value is very obvious.

[0182] FIG22 is an admittance curve of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=20°. As shown in FIG22 , it can be seen that when γ-θ=7°, the admittance ratio of the target acoustic wave mode is significantly improved compared to γ=0°, while the admittance ratios of the low-frequency Rayleigh mode, the high-frequency longitudinal leakage surface acoustic wave, and other high-order modes are all reduced.

[0183] FIG23 is an impedance phase curve diagram of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=20°. As shown in FIG23 , it can be seen from the figure that when γ-θ=7°, compared with γ=0°, the impedance phase amplitude of the target acoustic wave mode remains basically unchanged, and the impedance phase amplitudes of the Rayleigh mode in the low frequency band, the longitudinal leakage surface acoustic wave in the high frequency band, and other high-order modes all decrease. This shows that the solution proposed by the embodiment of the present application can improve the Q value of the target acoustic wave mode while weakening the parasitic mode.

[0184] FIG24 is a Bode-Q curve of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=20°. As shown in FIG24 , it can be seen that when γ-θ=7°, the Q value of the target acoustic wave mode is greatly improved compared to γ=0°.

[0185] Figure 25 is a target acoustic wave mode vibration shape diagram corresponding to Figure 17 when the acoustic wave propagation direction angle θ=20° and γ-θ=7°, provided in an embodiment of the present application. As shown in Figure 25, it can be seen from the figure that although the acoustic wave propagation direction is rotated by 20°, resulting in an energy flow angle of about 20°, by adjusting the gap trajectory, the energy flow incident angle η is only about 7°, so the acoustic wave energy is basically concentrated in the interdigitated electrode area, ensuring a higher Q value.

[0186] Figure 26 is a graph of the admittance and conductance of an acoustic wave resonator provided in an embodiment of the present application when the acoustic wave propagation direction angle θ=0° and γ=0°. As shown in Figure 26 , it can be seen from the figure that there is a transverse high-order mode between the resonant frequency and the anti-resonant frequency.

[0187] FIG27 shows the admittance and conductance curves of an acoustic resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ = 20° and γ-θ = 7°. As shown in FIG27 , the transverse high-order modes between the resonant frequency and the antiresonant frequency are substantially suppressed, and the energy inflow incident angle at this time is approximately 7°. Therefore, a smaller energy inflow incident angle can suppress transverse high-order modes.

[0188] FIG28 is a schematic diagram of the displacement distribution of the transverse high-order mode corresponding to an excessively small energy inflow incident angle η, an appropriate energy inflow incident angle η, and an excessively large energy inflow incident angle η provided in an embodiment of the present application. As shown in FIG28 , according to the excitation coefficient formula Where Φ is the displacement distribution of the lateral high-order mode, and W is the length of the overlapping area of ​​the forked electrodes. When the molecular integral is 0, the lateral high-order mode is suppressed, that is, the positive and negative shaded parts of the figure are offset. When the energy inflow incident angle η is too small, the vibration of the acoustic wave is concentrated in the overlapping area of ​​the forked electrodes, and a sinusoidal distribution appears, and the molecular integral is not 0. When the energy inflow incident angle η is moderate, the acoustic wave leaks to the pseudo-finger electrode, but does not leak to the bus bar area. At this time, due to the change in the displacement distribution, the molecular integral is 0. When the incident angle η is too large, both the lateral high-order mode and the target acoustic wave mode will leak to the bus bar, resulting in a decrease in the Q value of the acoustic resonator.

[0189] In this embodiment, an acoustic wave filter can be obtained by connecting the above acoustic wave resonators in series and in parallel.

[0190] Figure 29 is a schematic diagram of the structure of an acoustic wave filter according to an embodiment of the present application, and Table 1 is a parameter table of the acoustic wave filter. As shown in Figure 29, it can be seen that different acoustic wave resonators in the acoustic wave filter have different acoustic wave propagation directions and gap tangent directions. As shown in Table 1, to reduce bandwidth, acoustic wave resonators generally have a larger acoustic wave propagation direction angle θ.

[0191] Table 1 Parameters of an acoustic wave filter

[0192] Figure 30 shows the admittance curve and Bode-Q curve of each acoustic wave resonator corresponding to the acoustic wave filter shown in Table 1 provided in an embodiment of the present application. As shown in Figure 30, it can be seen from the figure that although the acoustic wave resonator has a large acoustic wave propagation direction angle θ, the Q value of each acoustic wave resonator is above 3000.

[0193] Figure 31 is an S-parameter curve corresponding to an acoustic wave filter in Table 1 provided in an embodiment of the present application. As shown in Figure 31, it can be seen from the figure that despite the large acoustic wave propagation direction angle θ, the insertion loss of the acoustic wave filter is about 1.07dB and the relative bandwidth is about 2.55%.

[0194] Figure 32 is a second schematic diagram of the structure corresponding to an acoustic wave filter provided in an embodiment of the present application. Table 2 provides a parameter table for the acoustic wave filter. As shown in Figure 32, it can be seen that different acoustic wave resonators in the acoustic wave filter have different acoustic wave propagation directions and gap tangent directions. The acoustic wave propagation direction angle θ is smaller than that in Table 1, indicating a larger target bandwidth.

[0195] Table 2 Parameters of an acoustic wave filter

[0196] Figure 33 shows the S21 curves corresponding to the acoustic wave filters shown in Tables 1 and 2, as provided in an embodiment of the present application. As shown in Figure 33 , the bandwidths of the two acoustic wave filters are 50 MHz and 68 MHz, respectively, with relative bandwidths of 2.55% and 3.47%, and insertion losses of 1.07 dB and 0.77 dB, respectively. The two acoustic wave filters exhibit low insertion losses and different relative bandwidths, demonstrating the feasibility of implementing acoustic wave filters with different relative bandwidths on the same piezoelectric substrate using the embodiments of the present application.

[0197] Figure 34 is a schematic diagram of the structure of a comparative acoustic wave filter, and Table 3 is a parameter table of the acoustic wave filter. As shown in Figure 30, it can be seen that different acoustic wave resonators in the acoustic wave filter have different acoustic wave propagation directions, and the gap tangent direction is the same as the acoustic wave propagation direction.

[0198] Table 3 Parameters of a comparative acoustic wave filter

[0199] FIG35 is an S-parameter curve corresponding to the acoustic wave filter in Table 3. As shown in FIG30 , it can be seen from the figure that due to the excessively large incident angle η of the energy flow, the insertion loss of the acoustic wave filter reaches 2.22 dB.

[0200] Figure 36 is a third structural diagram corresponding to an acoustic wave filter provided in an embodiment of the present application, and Table 4 is a parameter table of the acoustic wave filter. As shown in Figure 36, it can be seen that different acoustic wave resonators in the acoustic wave filter have different acoustic wave propagation directions, and the gap tangent direction is not parallel to the acoustic wave propagation direction.

[0201] Table 4 Parameters of an acoustic wave filter Table 3

[0202] Figure 37 is an S-parameter curve corresponding to an acoustic wave filter in Table 4 provided in an embodiment of the present application. As shown in Figure 37, it can be seen from the figure that since the energy inflow incident angle η is limited to a certain range, the insertion loss of the acoustic wave filter is reduced to 1.01dB.

[0203] Figure 38 is an S21 curve corresponding to an acoustic wave filter shown in Table 3 and Table 4 provided in an embodiment of the present application. As shown in Figure 38, the acoustic wave propagation directions of the acoustic wave resonators of the two acoustic wave filters are respectively the same, after limiting the energy flow incident angle η. The insertion loss of the acoustic wave filter in Table 4 is reduced from 2.22dB to 1.01dB compared with Table 3. This shows that by changing the tangent direction of the air gap to control the energy flow incident angle η, the loss caused by excessive energy flow angle during bandwidth adjustment can be compensated. In addition, the out-of-band fluctuations caused by the Rayleigh mode and the high-frequency mode near 2.8GHz are also weakened, which helps to improve the out-of-band suppression level.

[0204] Example 2:

[0205] Figure 39 is a ninth structural diagram of an acoustic wave resonator provided in an embodiment of the present application. As shown in Figure 39, the acoustic wave resonator includes, from bottom to top, a supporting substrate 40, a first intermediate dielectric layer 51, a second intermediate dielectric layer 52, a piezoelectric film 20, and a top electrode 10. The supporting substrate 40 is made of silicon, the first intermediate dielectric layer 51 is made of polycrystalline silicon, and its thickness is 1 μm. The second intermediate dielectric layer 52 is made of silicon oxide, and its thickness is 500 nm. The piezoelectric film 20 is Y42-cut lithium tantalate, and its thickness is 600 nm. The top electrode 10 is titanium / aluminum / titanium, and its thicknesses are 2 nm / 120 nm / 3 nm, respectively, and the first reference axis is the crystal X axis.

[0206] FIG40 is a diagram showing the Q value Qp at the anti-resonance frequency corresponding to different gap trajectory tangential angles γ and different acoustic wave propagation direction angles θ provided in an embodiment of the present application. As shown in FIG40 , it can be seen from the figure that when γ-θ is at 5° or γ-θ is near -6°, the Q value of the acoustic wave resonator remains above 3000. This is because the energy inflow incident angle η is moderate at this time. When γ-θ is far away from 5° or -6°, the Q value may be lower than 1000. This is because the energy inflow incident angle η is too large or too small at this time.

[0207] Figure 41 is an admittance curve diagram of an acoustic wave resonator provided in an embodiment of the present application when the sound wave propagation direction angle θ=0° and γ=-5°, and the sound wave propagation direction angle θ=4° and γ=10°. Figure 42 is a Bode-Q curve diagram of an acoustic wave resonator provided in an embodiment of the present application when the sound wave propagation direction angle θ=0° and γ=-5°, and the sound wave propagation direction angle θ=4° and γ=10°. As shown in Figures 41 and 42, it can be seen from the figures that the maximum Q value that can be obtained when the sound wave propagation direction angle θ≠0° is higher than when the sound wave propagation direction angle θ=0°. This is because the design dimension is increased, thereby more finely adjusting the energy flow incident angle η.

[0208] Figure 43 is an admittance curve of an acoustic wave resonator provided in an embodiment of the present application when γ is 0°, the acoustic wave propagation direction angle θ=0° and the acoustic wave propagation direction angle θ=20°. Figure 44 is a Bode-Q curve of an acoustic wave resonator provided in an embodiment of the present application when γ is 0°, the acoustic wave propagation direction angle θ=0° and the acoustic wave propagation direction angle θ=20°. As shown in Figures 43 and 44, it can be seen from the figures that when the acoustic wave propagation direction angle θ=20° is relative to the acoustic wave propagation direction angle θ=0°, the Q value decreases significantly due to the increase in the energy inflow incident angle.

[0209] FIG45 shows the electromechanical coupling coefficients k2 and Qp corresponding to different acoustic wave propagation direction angles θ extracted from another set of experimental results provided by an embodiment of the present application. As shown in FIG45 , it can be seen from the figure that when γ-θ = 6°, the Q value of the acoustic wave resonator remains above 2500, and the highest exceeds 4000. When the acoustic wave propagation direction angle θ is greater than 10°, the Q value corresponding to γ ​​= 0° drops significantly. This proves that the acoustic wave energy loss can be effectively reduced by reducing the energy inflow incident angle η by changing the tangential direction of the air gap.

[0210] FIG46 is an admittance curve of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=20°. As shown in FIG46 , it can be seen that when γ-θ=6°, the admittance ratio of the target acoustic wave mode is significantly improved compared to γ=0°, while the admittance ratios of the low-frequency Rayleigh mode, the high-frequency longitudinal leakage surface acoustic wave, and other high-order modes are all reduced.

[0211] FIG47 is an impedance phase curve diagram of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=20°. As shown in FIG47 , it can be seen from the figure that when γ-θ=6°, compared with γ=0°, the impedance phase amplitude of the target acoustic wave mode remains basically unchanged, while the impedance phase amplitudes of the Rayleigh mode in the low frequency band, the longitudinal leakage surface acoustic wave in the high frequency band, and other high-order modes all decrease. This shows that the solution provided by the embodiment of the present application can improve the Q value of the target acoustic wave mode while weakening the parasitic mode.

[0212] FIG48 is a Bode-Q curve of an acoustic wave resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ=20°. As shown in FIG48 , it can be seen that when γ-θ=6°, the Q value of the target acoustic wave mode is greatly improved compared to γ=0°.

[0213] Table 5 is a parameter table 4 of an acoustic wave filter provided in an embodiment of the present application. Except for the piezoelectric substrate being different from that in Table 4, the parameters of the acoustic wave filter in Table 5 are the same as those in Table 4.

[0214] Table 5 Parameters of an acoustic wave filter Table 4

[0215] Figure 49 is a fifth structural diagram corresponding to an acoustic wave filter provided in an embodiment of the present application, and Table 6 is a parameter table of the acoustic wave filter. As shown in Figure 49, it can be seen that different acoustic wave resonators in the acoustic wave filter have different acoustic wave propagation directions, and the gap tangent direction is not parallel to the acoustic wave propagation direction.

[0216] Table 6 Parameters of an acoustic wave filter Table 5

[0217] Figure 50 shows the S-parameter curves corresponding to the acoustic wave filters shown in Tables 5 and 6, as provided in the embodiments of this application. As shown in Figure 50 , the bandwidths of the two acoustic wave filters are 47 MHz and 65 MHz, respectively, with relative bandwidths of 2.47% and 3.41%, and insertion losses of 1.05 dB and 0.9 dB, respectively. The two acoustic wave filters have low insertion losses and different relative bandwidths. This demonstrates the feasibility of implementing acoustic wave filters with different relative bandwidths on the same piezoelectric substrate, as proposed in the embodiments of this application.

[0218] Example 3:

[0219] Figure 51 is a schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application. As shown in Figure 51 , the acoustic wave resonator comprises, from bottom to top, a supporting substrate 40, a piezoelectric film 20, and a top electrode 10. The supporting substrate 40 is made of silicon. The piezoelectric film 20 is X-cut lithium tantalate with a thickness of 600 nm. The top electrode 10 is aluminum with a thickness of 150 nm. The first reference axis is the crystal's Y-axis.

[0220] Figure 52 shows the variation of the electromechanical coupling coefficient k2, the energy flow angle τ of the target acoustic wave mode and the parasitic mode of an acoustic wave resonator provided by an embodiment of the present application with the acoustic wave propagation direction angle θ. As shown in Figure 52, when the acoustic wave propagation direction angle θ = 167°, the electromechanical coupling coefficient of the target acoustic wave mode SH0 mode reaches its maximum, and at this time, the difference between the energy flow angle of the Rayleigh mode and the SH0 mode is 1°. When the acoustic wave propagation direction deviates from the direction where k2 takes an extreme value, the energy flow angle of the target acoustic wave mode increases. When the acoustic wave propagation direction angle θ = 157°, the difference between the energy flow angle of the Rayleigh mode and the SH0 mode is 10°, and the k2 of the target acoustic wave mode is still above 9%.

[0221] Figure 53 is an admittance curve of an acoustic wave resonator provided in an embodiment of the present application when the sound wave propagation direction angle θ is 157°, γ = 0° and γ = -20°. As shown in Figure 53, when γ = -20° is compared with γ = 0°, the admittance ratio of the target acoustic wave mode increases, while the admittance ratio of the Rayleigh mode decreases. This is because at this time the energy inflow incident angle of the Rayleigh mode reaches 20°, while the energy inflow incident angle of the target acoustic wave mode is still within 15°.

[0222] Figure 54 shows an impedance phase curve of an acoustic resonator provided by an embodiment of the present application when the acoustic wave propagation direction angle θ is 157°, γ = 0°, and γ = -20°. As shown in Figure 54, the phase amplitude of the Rayleigh mode is significantly reduced when γ = -20° compared to γ ​​= 0°. Therefore, parasitic modes can be suppressed by ensuring that the energy flow directions of the parasitic mode and the target acoustic wave mode are different.

[0223] The embodiments of the present application address the problem that it is difficult to adjust the electromechanical coupling coefficient of existing acoustic wave resonators, as well as the complex process or increased loss associated with adjusting the electromechanical coupling coefficient. It is proposed to use a single crystal piezoelectric film with strong in-plane anisotropy to adjust the electromechanical coupling coefficient by changing the in-plane acoustic wave propagation direction of the acoustic wave, while controlling the angle between the tangent direction of the gap track and the energy flow direction of the target acoustic wave mode to avoid energy leakage caused by excessive energy flow incident angles. Acoustic wave resonators with different electromechanical coupling coefficients are implemented on the same piezoelectric film, thereby realizing acoustic wave filters with different relative bandwidths. Acoustic wave resonators with different electromechanical coupling coefficients are used to form an acoustic wave filter to meet the requirements of multi-zero point design and obtain a flatter passband. At the same time, the tangent direction of the gap track is not completely parallel to the energy flow direction of the target acoustic wave mode to suppress lateral high-order modes. In addition, by selecting a suitable in-plane direction, the energy flow direction of the out-of-band parasitic mode can be made significantly different from the energy flow direction of the target acoustic wave mode, thereby allowing the out-of-band parasitic mode to leak into the busbar area while maintaining a high Q value of the target acoustic wave mode, thereby improving the out-of-band suppression level.

[0224] It should be noted that the order of the embodiments of the present application described above is for descriptive purposes only and does not represent the superiority or inferiority of the embodiments. The above description is of specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0225] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the device embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0226] Those skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware, or may be accomplished by a program to instruct the relevant hardware, and the program may be stored in a computer-readable storage medium, which may be a read-only memory, a disk, or an optical disk, etc.

[0227] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. An acoustic wave resonator, characterized in that include: A piezoelectric film and a top electrode disposed on a first surface of the piezoelectric film; The top electrode includes a first finger electrode and a second finger electrode; The first finger-shaped electrode includes a preset number of first electrode fingers and first dummy finger electrodes, and the first electrode fingers are spaced apart from the first dummy finger electrodes; The second finger-shaped electrode includes a preset number of second electrode fingers and second dummy finger electrodes, and the second electrode fingers are spaced apart from the second dummy finger electrodes; The first electrode fingers and the second electrode fingers are arranged crosswise, and adjacent first electrode fingers and second electrode fingers form an interdigitated electrode pair; The first electrode finger strips are arranged opposite to the second dummy electrode strips, and a first gap track is formed between the first electrode finger strips and the second dummy electrode strips; The second electrode finger strips are arranged opposite to the first dummy electrode strips, and a second gap track is formed between the second electrode finger strips and the first dummy electrode strips; A preset crystal axis in the piezoelectric film is used as a first reference axis, a normal direction of the interdigital electrode pair is used as a second reference axis, and a preset angle is formed between the first reference axis and the second reference axis; The angle between the average tangent of the first gap trajectory and the second reference axis is the first gap trajectory tangential angle, and the angle between the average tangent of the second gap trajectory and the second reference axis is the second gap trajectory tangential angle. The first gap trajectory tangential angle and the second gap trajectory tangential angle meet preset conditions.

2. The acoustic wave resonator according to claim 1, characterized in that The electromechanical coupling coefficient of the acoustic wave resonator satisfies the following conditions: (k2 max -k2 30° ) / k2 max ≥30%; Among them, k2 max is the maximum value of the electromechanical coupling coefficient when the sound wave propagates in different directions, k2 30° relative to Maximum electromechanical coupling value. Electromechanical coupling coefficient after the crystal axis orientation is rotated by 30°.

3. The acoustic wave resonator according to claim 1, wherein The material of the piezoelectric film is one of lithium niobate, lithium tantalate and potassium niobate.

4. The acoustic wave resonator according to claim 3, characterized in that The piezoelectric film is X-cut lithium niobate or lithium tantalate, the target acoustic wave mode in the acoustic wave resonator is a 0th-order horizontal shear mode, and the preset crystal axis is the Y axis; The preset angle is from 0° to 45°, or from 130° to 180°.

5. The acoustic wave resonator according to claim 3, characterized in that The piezoelectric film is a rotated Y-cut lithium niobate or lithium tantalate, the target acoustic wave mode in the acoustic wave resonator is a 0th-order horizontal shear mode, and the preset crystal axis is the X-axis; The preset angle is between -40° and 40°.

6. The acoustic wave resonator according to claim 1, characterized in that The direction of the acoustic wave energy flow of the acoustic wave resonator is taken as a third reference axis, and the angle between the second reference axis and the third reference axis is a reference energy flow angle; The tangential angle of the first gap trajectory meets the following preset conditions: in, is the first gap trajectory tangential angle, τ' is the reference energy flow angle; The tangential angle of the second gap trajectory meets the following preset conditions: in, is the tangential angle of the second gap trajectory, and τ' is the reference energy flow angle.

7. The acoustic wave resonator according to claim 6, characterized in that The angle between the tangent of the first gap track at any of the first electrode fingers and the third reference axis is the first energy inflow incident angle, and the angle between the tangent of the second gap track at any of the second electrode fingers and the third reference axis is the second energy inflow incident angle, and at least one maximum value of the first energy inflow incident angle or at least one maximum value of the second energy inflow incident angle is greater than or equal to 1°.

8. The acoustic wave resonator according to claim 6 or 7, characterized in that The reference energy flow angle is not equal to 0.

9. The acoustic wave resonator according to claim 8, characterized in that The length of the first dummy electrode satisfies the following condition: 1i ≥5λ×tan(|γ 2i -τ'|), Among them, L 1i is the length of the i-th first dummy finger electrode in the first finger electrode, γ 2i is the angle between the tangent line of the second gap trajectory at the i-th first pseudo-finger electrode and the second reference axis, and τ' is the reference energy flow angle; The length of the second dummy electrode satisfies the following conditions: L 2i ≥5λ×tan(|γ 1i -t'|); Among them, L 2i is the length of the i-th second pseudo-finger electrode in the second finger electrode, γ 1i is the angle between the tangent line of the first gap track at the i-th second dummy electrode and the second reference axis, and τ' is the reference energy flow angle.

10. The acoustic wave resonator according to claim 1, wherein The first gap trajectory is a straight line; and / or, The second gap trajectory is a straight line.

11. The acoustic wave resonator according to claim 1 or 10, characterized in that The first gap track and the second gap track are parallel.

12. The acoustic wave resonator according to claim 1, wherein The distance between adjacent first electrode fingers and the distance between adjacent second electrode fingers are both λ; The length of the intersection region between the first electrode finger and the second electrode finger in the interdigitated electrode pair is 5λ to 40λ.

13. The acoustic wave resonator according to claim 12, characterized in that The thickness of the piezoelectric film is 0.1λ to 1λ.

14. The acoustic wave resonator according to claim 1 or 12, characterized in that The piezoelectric film is rotated Y-cut, and the cutting angle is 0° to 75°.

15. The acoustic wave resonator according to claim 1, wherein The top electrode further includes a first reflection grating and a second reflection grating, and the first reflection grating and the second reflection grating are respectively arranged on both sides of a preset number of interdigital electrode pairs.

16. The acoustic wave resonator according to claim 1, wherein The acoustic wave resonator further includes a bottom electrode disposed on a second surface of the piezoelectric film, the second surface being opposite to the first surface.

17. The acoustic wave resonator according to claim 16, characterized in that The bottom electrode is a surface electrode.

18. The acoustic wave resonator according to claim 16, wherein The bottom electrode is an interdigitated electrode, and the electrode fingers of the bottom electrode correspond one-to-one with the electrode fingers in the top electrode.

19. The acoustic wave resonator according to claim 1 or 16, characterized in that The acoustic wave resonator further includes a supporting substrate, and the piezoelectric film is disposed on the supporting substrate.

20. The acoustic wave resonator according to claim 19, wherein The material of the support substrate is one of sapphire, silicon, spinel, silicon carbide, diamond, diamond-like carbon, silicon nitride, boron nitride, boron carbide, quartz, germanium, aluminum nitride, silicon nitride, yttrium aluminum garnet, lithium tantalate, and lithium niobate.

21. The acoustic wave resonator according to claim 19 or 20, characterized in that At least one intermediate dielectric layer is provided between the piezoelectric film and the supporting substrate.

22. The acoustic wave resonator according to claim 21, characterized in that The material of the intermediate dielectric layer is at least one of silicon oxide, aluminum oxide, aluminum nitride, silicon nitride, polysilicon, and amorphous silicon.

23. The acoustic wave resonator according to claim 19 or 20, characterized in that A Bragg reflection layer is further provided between the piezoelectric film and the supporting substrate.

24. The acoustic wave resonator according to claim 1, wherein A load structure is provided in the area where the first electrode fingers correspond to the second gap tracks and in the area where the second electrode fingers correspond to the first gap tracks.

25. The acoustic wave resonator according to claim 24, characterized in that The load structure is at least one of a load block, a load bar, and a widened electrode finger bar.

26. An acoustic wave filter, characterized in that The acoustic wave filter includes at least one acoustic wave resonator according to any one of claims 1 to 25.

27. The acoustic wave filter according to claim 26, wherein The acoustic wave filter comprises at least two acoustic wave resonators according to any one of claims 1 to 25; At least two of the acoustic wave resonators correspond to at least two preset angles of different sizes.

28. The acoustic wave filter according to claim 27, wherein The at least two acoustic wave resonators include a series acoustic wave resonator and a parallel acoustic wave resonator; The average angle of the first gap track tangent angle and the second gap track tangent angle in the series acoustic wave resonator is greater than the average angle of the first gap track tangent angle and the second gap track tangent angle in the parallel acoustic wave resonator.

29. An acoustic wave filter module, characterized in that: The acoustic wave filter module includes the acoustic wave filter according to any one of claims 26 to 28.

30. The acoustic wave filter module according to claim 29, wherein The acoustic wave filter module includes at least two acoustic wave filters, and the at least two acoustic wave filters are formed on the same piezoelectric film.

31. The acoustic wave filter module according to claim 29 or 30, wherein: In the acoustic wave filter module, the maximum relative bandwidth of the acoustic wave filter and the minimum relative bandwidth of the acoustic wave filter meet the following conditions: (FBW max -FBW min ) / FBW min ≥10%; Among them, FBW max FBW is the maximum relative bandwidth of the acoustic wave filter in the acoustic wave filter module. min is the minimum relative bandwidth of the acoustic wave filter in the acoustic wave filter module.

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