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

Abstract

The invention relates to the technical field of semiconductors, in particular to an acoustic resonator, an acoustic filter and an acoustic filter module. The acoustic resonator at least comprises a piezoelectric film and an interdigital electrode; a preset crystal axis in the piezoelectric film serves as a first reference axis, the normal direction of the interdigital electrode pair serves as a second reference axis, and a preset included angle is formed between the first reference axis and the second reference axis; the average tangential direction of the first gap track and the average tangential direction of the second gap track in the interdigital electrode meet a preset condition. The electromechanical coupling coefficient of the acoustic resonator is adjusted by changing the acoustic wave propagation direction in the acoustic wave surface. Moreover, by designing a first gap track tangential angle and a second gap track tangential angle, the electromechanical coupling coefficient of the acoustic resonator is changed, and energy leakage caused by an overlarge 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 are realized.

Description

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 smart phones has increased to 50 or even more than 100. Acoustic wave filters in different frequency bands generally have different frequencies and bandwidths. In addition, there are also some frequency bands with similar frequencies but large differences in bandwidth, such as Band 3, Band 4, and Band 9, whose operating frequencies are all between 1.7 and 1.8 GHz, but their bandwidths are 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 resonator that constitutes the acoustic wave filter.

[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 relative bandwidths need to be achieved through different scandium doping concentrations. 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. Summary of the invention

[0004] 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.

[0005] 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;

[0006] The top electrode includes a first finger electrode and a second finger electrode;

[0007] The first finger-shaped electrode comprises 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;

[0008] The second finger-shaped electrode comprises 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;

[0009] The first electrode fingers and the second electrode fingers are arranged crosswise, and adjacent first electrode fingers and second electrode fingers form interdigitated electrode pairs;

[0010] The first electrode finger strip is arranged opposite to the second dummy electrode finger, and a first gap track is formed between the first electrode finger strip and the second dummy electrode finger;

[0011] 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;

[0012] 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;

[0013] The average tangent of the first gap track and the angle between it and the second reference axis are the first gap track tangent angle, the average tangent of the second gap track and the angle between it and the second reference axis are the second gap track tangent angle, and the first gap track tangent angle and the second gap track tangent angle meet preset conditions.

[0014] In some optional embodiments, the electromechanical coupling coefficient of the acoustic wave resonator satisfies the following conditions:

[0015] (k2 max -k2 30° ) / k2 max ≥30%;

[0016] Among them, k2 max k2 is the maximum value of the electromechanical coupling coefficient when the sound wave propagates in different directions. 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 from 0° to 45°, or from 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 between -40° and 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]

[0025] in, is the tangential angle of the first gap trajectory, τ' is the reference energy flow angle;

[0026] The tangential angle of the second gap trajectory meets the following preset conditions:

[0027]

[0028] in, is the tangential angle of the second gap trajectory, and τ' is the reference energy flow angle.

[0029] 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 inflow 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 inflow incident angle, and the maximum value of at least one first energy inflow incident angle or the maximum value of at least one second energy inflow incident angle is greater than or equal to 1°.

[0030] In some optional embodiments, the reference energy flow angle is not equal to 0.

[0031] In some optional embodiments, the length of the first dummy electrode satisfies the following conditions:

[0032] L 1i ≥5λ×tan(|γ 2i -τ'|),

[0033] Among them, L 1i is the length of the i-th first pseudo-finger electrode in the first finger electrode, γ 2i is the angle between the tangent line of the second gap track at the i-th first pseudo-finger electrode and the second reference axis, and τ' is the reference energy flow angle;

[0034] The length of the second fake finger electrode meets the following conditions:

[0035] L 2i ≥5λ×tan(|γ 1i -τ'|);

[0036] Among them, L 2iis the length of the i-th second pseudo-finger electrode in the second finger electrode, γ 1i is the angle between the tangent of the first gap track at the i-th second fake finger electrode and the second reference axis, and τ' is the reference energy flow angle.

[0037] In some optional embodiments, the first gap trajectory is a straight line; and / or,

[0038] The second gap trajectory is a straight line.

[0039] In some optional embodiments, the first gap track is parallel to the second gap track.

[0040] In some optional embodiments, the distance between adjacent first electrode fingers and the distance between adjacent second electrode fingers are both λ;

[0041] 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.

[0042] In some optional embodiments, the thickness of the piezoelectric film is 0.1λ to 1λ.

[0043] In some optional embodiments, the piezoelectric film is rotated Y-cut, and the cutting angle is 0° to 75°.

[0044] 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.

[0045] 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, the second surface being opposite to the first surface.

[0046] In some optional embodiments, the bottom electrode is a surface electrode.

[0047] 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.

[0048] In some optional embodiments, the acoustic wave resonator further includes a supporting substrate, and the piezoelectric film is disposed on the supporting substrate.

[0049] 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.

[0050] In some optional embodiments, at least one intermediate dielectric layer is disposed between the piezoelectric film and the supporting substrate.

[0051] In some optional embodiments, the material of the intermediate dielectric layer is at least one of silicon oxide, aluminum oxide, aluminum nitride, silicon nitride, polycrystalline silicon, and amorphous silicon.

[0052] In some optional embodiments, a Bragg reflection layer is further provided between the piezoelectric film and the supporting substrate.

[0053] In some optional embodiments, a load structure is provided in an area corresponding to the first electrode finger and the second gap track, and in an area corresponding to the second electrode finger and the first gap track.

[0054] In some optional embodiments, the load structure is at least one of a load block, a load bar, and a widened electrode finger bar.

[0055] 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.

[0056] In some optional embodiments, the acoustic wave filter includes at least two acoustic wave resonators as described above;

[0057] At least two acoustic wave resonators correspond to at least two preset angles of different sizes.

[0058] In some optional embodiments, the at least two acoustic wave resonators include a series acoustic wave resonator and a parallel acoustic wave resonator;

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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:

[0063] (FBW max -FBW min ) / FBW min ≥10%;

[0064] Among them, FBW max The maximum relative bandwidth of the acoustic wave filter in the acoustic wave filter module, FBW minIt is the minimum relative bandwidth of the acoustic wave filter in the acoustic wave filter module.

[0065] The technical solution provided by the embodiment of the present application has the following technical effects:

[0066] The acoustic wave resonator, acoustic wave filter and acoustic wave filter module described in the embodiment of the present application utilize a single crystal piezoelectric film with in-plane anisotropy, and by designing a preset angle between a pair of interdigitated electrodes and a 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, the energy leakage caused by the 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 energy flow angle of the target acoustic wave mode propagated in the acoustic wave resonator is made to have a large gap with the energy flow angle of the out-of-band parasitic mode, and then with a suitable gap track tangent angle, it is achieved that while maintaining the high quality factor of the target acoustic wave mode, the out-of-band parasitic mode is leaked out, thereby improving the out-of-band suppression level. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0068] Figure 1 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 1 ;

[0069] Figure 2 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 1 ;

[0070] Figure 3 is the change of phase velocity, electromechanical coupling coefficient k2, and energy flow angle τ of an acoustic resonator with the acoustic wave propagation direction angle θ;

[0071] Figure 4 It is a schematic diagram of the change of the direction of the acoustic wave energy flow and the tangent direction of the gap trajectory of an acoustic wave resonator with the angle θ of the acoustic wave propagation direction;

[0072] Figure 5 It is a schematic diagram of the anti-resonance frequency Q value Qp of an acoustic wave resonator changing with the acoustic wave propagation direction angle θ;

[0073] Figure 6 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 2 ;

[0074] Figure 7 for Figure 6 The corresponding admittance curves when θ=0° and θ=20°, where γ is 0°;

[0075] Figure 8 for Figure 6 The corresponding Bode-Q curves when θ = 0° and θ = 20°, where γ is 0°;

[0076] Fig. 9 for Figure 6 The corresponding main mode vibration shape diagram when θ = 20°, where γ is 0°;

[0077] Fig.10 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 2 ;

[0078] Fig.11 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 3 ;

[0079] Fig.12 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 4 ;

[0080] Fig.13 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 5 ;

[0081] Fig.14 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 6 ;

[0082] Fig.15 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 7 ;

[0083] Fig.16 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 3 ;

[0084] Fig.17 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 4 ;

[0085] Fig.18 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 8 ;

[0086] Fig.19 A schematic diagram of a proposed acoustic wave resonator in which the direction of acoustic wave energy flow and the tangent direction of the gap trajectory change with the angle θ of the acoustic wave propagation direction provided in an embodiment of the present application;.

[0087] Fig. 20 A method provided in the embodiment of the present application Figure 6 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;

[0088] Fig.21 The electromechanical coupling coefficients k2 and Qp corresponding to different sound wave propagation direction angles θ extracted from another set of experimental results provided in an embodiment of the present application;

[0089] Fig. 22 An admittance curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided in an embodiment of the present application;

[0090] Fig.23 An impedance phase curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided in an embodiment of the present application;

[0091] Fig.24 A Bode-Q curve diagram of an acoustic wave resonator when the acoustic wave propagation direction angle θ=20° provided in an embodiment of the present application;

[0092] Fig.25 A method provided in the embodiment of the present application Fig.17 The corresponding target acoustic mode vibration shape diagram when the acoustic wave propagation direction angle θ = 20° and γ-θ = 7°;

[0093] Fig.26 A graph of the admittance and conductance of an acoustic wave resonator when the acoustic wave propagation direction angle θ=0° and γ=0° provided in an embodiment of the present application;

[0094] Fig. 27 A graph of the admittance and conductance of an acoustic wave resonator when the acoustic wave propagation direction angle θ=20° and γ-θ=7° provided in an embodiment of the present application;

[0095] Fig.28 A schematic diagram of displacement distribution of a lateral high-order mode corresponding to an excessively small energy inflow incident angle η, a suitable energy inflow incident angle η, and an excessively large energy inflow incident angle η provided in an embodiment of the present application;

[0096] Fig.29 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 1 ;

[0097] Fig.30Admittance curve and 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;

[0098] Fig.31 Table 1 is an S parameter curve corresponding to an acoustic wave filter provided in an embodiment of the present application;

[0099] Fig.32 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 2 ;

[0100] Fig.33 An S21 curve corresponding to an acoustic wave filter shown in Table 1 and Table 2 provided in an embodiment of the present application;

[0101] Fig.34 A schematic diagram of the structure corresponding to a comparative acoustic wave filter;

[0102] Fig.35 Table 3 is the S parameter curve corresponding to the acoustic wave filter;

[0103] Fig.36 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 3 ;

[0104] Fig.37 Table 4 is an S parameter curve corresponding to the acoustic wave filter provided in the embodiment of the present application;

[0105] Fig.38 An S21 curve corresponding to an acoustic wave filter shown in Table 3 and Table 4 provided in an embodiment of the present application;

[0106] Fig.39 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 9 ;

[0107] Fig.40 A Q value Qp at an anti-resonance frequency corresponding to a different gap track tangential angle γ and a different sound wave propagation direction angle θ provided in an embodiment of the present application;

[0108] Fig.41 An admittance curve diagram of an acoustic wave resonator provided in 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°;

[0109] Fig.42 A Bode-Q curve diagram of an acoustic wave resonator provided in 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°;

[0110] Fig.43An 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°;

[0111] Fig.44 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°;

[0112] Fig.45 The electromechanical coupling coefficients k2 and Qp corresponding to different sound wave propagation direction angles θ extracted from another set of experimental results provided in an embodiment of the present application;

[0113] Fig.46 An admittance curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided in an embodiment of the present application;

[0114] Fig.47 An impedance phase curve diagram of an acoustic wave resonator when an acoustic wave propagation direction angle θ=20° provided in an embodiment of the present application;

[0115] Fig.48 A Bode-Q curve diagram of an acoustic wave resonator when the acoustic wave propagation direction angle θ=20° provided in an embodiment of the present application;

[0116] Fig.49 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 5 ;

[0117] Fig.50 An S parameter curve corresponding to the acoustic wave filter shown in Table 5 and Table 6 provided in an embodiment of the present application;

[0118] Fig.51 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 10 ;

[0119] Fig.52 The electromechanical coupling coefficient k2 of an acoustic wave resonator provided in an embodiment of the present application, and the energy flow angle τ of a target acoustic wave mode and a parasitic mode change with the acoustic wave propagation direction angle θ;

[0120] Fig.53 An admittance curve of an acoustic wave resonator when the acoustic wave propagation direction angle θ is 157°, γ=0° and γ=-20° provided in an embodiment of the present application;

[0121] Fig.54 An impedance phase curve of an acoustic wave resonator provided in an embodiment of the present application when the acoustic wave propagation direction angle θ is 157°, γ=0° and γ=-20°.

[0122] The following is a supplementary description of the attached drawings:

[0123] 10-top electrode; 110-first finger electrode; 111-first electrode finger strip; 112-first pseudo-finger electrode; 113-first bus bar; 120-second finger electrode; 121-second electrode finger strip; 122-second pseudo-finger 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

[0124] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0125] It should be noted that the "one embodiment" or "embodiment" referred to in the specification of the embodiment of the present application refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present application. It should be understood that in the specification and claims of the embodiment of the present application and the above-mentioned drawings, the orientation or position relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, in the description of the present embodiment, unless otherwise specified, the meaning of "plurality" is 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 including a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0126] In order to make the purpose, technical solution 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 used to limit the embodiments of the present application.

[0127] In view of the problem that it is difficult to be compatible with frequency bands of different relative bandwidths based on a single material system, the embodiment of the present application proposes 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, the energy leakage caused by the 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 being able to improve 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 appropriate gap track and the energy flow direction, the radiation of the acoustic wave to the bus bar is avoided, and a high quality factor (Q value) is maintained.

[0128] See also Figure 1 , Figure 1 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 1 ,like Figure 1 As shown, the acoustic wave resonator includes: a piezoelectric film 20 and a top electrode 10 disposed on a first surface of the piezoelectric film 20 .

[0129] In the embodiment of the present application, the top electrode 10 is an interdigitated electrode. Figure 2 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 1 ,like Figure 2 As shown, the top electrode 10 includes a first finger electrode 110 and a second finger electrode 120 .

[0130] like Figure 2 As shown, 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 arranged at intervals from each other. Optionally, in the first finger electrode 110, the number of the first electrode fingers 111 and the number of the first dummy electrodes 112 may be the same or different, for example, the number of the first electrode fingers 111 is one more than the number of the first dummy electrodes 112, or the number of the first electrode fingers 111 is one less than the number of the 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.

[0131] like Figure 2As shown, 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 arranged at intervals from each other. Optionally, in the second finger electrode 120, the number of the second electrode fingers 121 and the number of the second dummy electrodes 122 may be the same or different, for example, the number of the second electrode fingers 121 is one more than the number of the second dummy electrodes 122, or the number of the second electrode fingers 121 is one less than the number of the second dummy electrodes 122. In addition, the number of the second electrode fingers 121 and the number of the first electrode fingers 111 may be the same or different, for example, the number of the second electrode fingers 121 is one more than the number of the first electrode fingers 111, or the number of the second electrode fingers 121 is one less than the number of the first electrode fingers 111. In the second finger electrode 120, the arrangement period of the second electrode fingers 121 is 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.

[0132] like Figure 2 As shown, 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.

[0133] In the top electrode 10, the first electrode finger 111 is arranged opposite to the second pseudo-finger electrode 122, and the second electrode finger 121 is arranged opposite to the first pseudo-finger electrode 112. That is, in the top electrode 10, each first electrode finger 111 corresponds to a second pseudo-finger electrode 122, and similarly, each second electrode finger 121 corresponds to a first pseudo-finger electrode 112. For any pair of first electrode fingers 111 and second pseudo-finger electrodes 122 having a corresponding relationship, the two are not in contact, that is, there is a gap between the two. By fitting the gaps between all the first electrode fingers 111 and second pseudo-finger electrodes 122 having a corresponding relationship with a smooth curve, a curve can be obtained, and the curve can be called a first gap track. Similarly, for any pair of second electrode fingers 121 and first pseudo-finger electrodes 112 having a corresponding relationship, the two are not in contact, that is, there is a gap between the two. By fitting the gaps between all the second electrode fingers 121 and first pseudo-finger electrodes 112 having a corresponding relationship with a smooth curve, a curve can be obtained, and the curve can be called a second gap track.

[0134] For an acoustic wave resonator, the acoustic wave propagation direction corresponding to the target acoustic wave mode transmitting 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 acoustic wave energy flow direction and the acoustic wave propagation direction in the acoustic wave resonator is the energy flow angle. In an acoustic wave resonator, the acoustic wave energy flow direction is the group velocity direction. Reference Figure 2 As shown, 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.

[0135] In an acoustic wave resonator, the angle between the gap track and the acoustic wave propagation direction is the gap track tangent angle γ. When the gap track is a curve, the angle between the tangent line of the gap track and the acoustic wave propagation direction can be taken as the gap track tangent angle. Figure 2 As shown, 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 through 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 through 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.

[0136] In addition, reference Figure 2 As shown, in the acoustic wave 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 represented by 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 direction of the crystal axis, it is sometimes clockwise and sometimes counterclockwise. The gap trajectory tangential angle γ is always counterclockwise. Therefore, 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.

[0137] For the acoustic wave resonator, the propagation directions of the acoustic waves with an energy flow angle of 0 corresponding to different target acoustic wave modes are different. Figure 3 is the change of phase velocity, electromechanical coupling coefficient k2, and energy flow angle τ of an acoustic resonator with the acoustic wave propagation direction angle θ. Figure 3 As shown in the figure, 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 the gap 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.

[0138] Figure 4 It is a schematic diagram of the change of the direction of the acoustic wave energy flow and the tangent of the gap trajectory of an acoustic wave resonator with the angle θ of the acoustic wave propagation direction, as shown in Figure 4 As shown, when the sound wave propagation direction angle θ≠0°, a large angle may appear between the direction of the sound wave energy flow and the tangent direction of the gap trajectory. Figure 5 It is a schematic diagram of the anti-resonance frequency Q value Qp of an acoustic wave resonator changing with the acoustic wave propagation direction angle θ, as shown in Figure 5 As shown in the figure, when the sound wave propagation direction angle θ increases from 0° to 4°, Qp increases. This is because the lateral high-order modes near the antiresonance frequency are suppressed, and a variety of existing methods for suppressing lateral high-order modes can achieve this effect. When the sound wave propagation direction angle θ is greater than 5°, Qp begins to drop sharply. This is because the direction of the sound wave energy flow and the tangent direction of the gap trajectory have too large an angle, that is, too large an energy flow incident angle η. 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 for Figure 6 The corresponding admittance curves when θ=0° and θ=20°, where γ is 0°, Figure 8 for Figure 6 The corresponding Bode-Q curves when θ=0° and θ=20°, where γ is 0°. It can be seen from the figure that when θ=20°, compared with θ=0°, although the purpose of adjusting the electromechanical coupling coefficient is achieved, the Q value drops significantly. Fig. 9 for Figure 6 The corresponding main mode vibration shape diagram when θ = 20°, where γ is 0°, such as Fig. 9 As shown in the figure, 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 bus bar area, which is the main reason for the decrease in Q value.

[0139] In the embodiment of the present application, since the piezoelectric film 20 has in-plane anisotropy, the electromechanical coupling coefficients corresponding to different in-plane directions are different. Therefore, by changing the in-plane propagation direction of the sound wave, an acoustic resonator with different electromechanical coupling coefficients can be realized on a piezoelectric film 20.

[0140] 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 cutting 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.

[0141] 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° ) / k2max ≥30%. Among them, k2 max k2 is the maximum value of the electromechanical coupling coefficient when the sound wave propagates in different directions. 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 may be a 0th order horizontal shear mode, a 0th order longitudinal leakage surface acoustic wave mode, a 0th order Rayleigh mode, etc.

[0142] 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 to say, 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°.

[0143] As another optional embodiment, the piezoelectric film 20 is a lithium niobate or lithium tantalate with a rotational Y-cut, 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 to say, when the piezoelectric film 20 is lithium niobate or lithium tantalate, the cut is a rotational 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 X-axis of the crystal, the acoustic wave propagation direction angle θ=0°, then the acoustic wave propagation direction range is -40°<acoustic wave propagation direction angle θ<40°.

[0144] In some embodiments, the sound wave propagation direction angle may not be 0, that is, the sound wave propagation direction angle θ≠0°.

[0145] In the acoustic wave resonator, the angle between the tangent direction of the gap trajectory and the direction of acoustic wave propagation is γ, and the angle between the tangent direction of the gap trajectory 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 trajectory 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 trajectory and the tangent direction of the second gap trajectory. In other words, the tangent angle of the first gap trajectory and the tangent angle of the second gap trajectory need to meet the preset conditions.

[0146] 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;

[0147] The tangential angle of the first gap trajectory meets the following preset conditions:

[0148]

[0149] 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.

[0150] The tangential angle of the second gap trajectory meets the following preset conditions:

[0151]

[0152] 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.

[0153] In an embodiment of the present application, the angle between the tangent of the first gap trajectory at any first electrode finger and the third reference axis is the first energy flow incident angle, the angle between the tangent of the second gap trajectory 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 at least one second energy flow incident angle is greater than or equal to 1°.

[0154] 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'|.

[0155] Specifically, the length of the first dummy electrode 112 satisfies the following conditions:

[0156] L 1i≥5λ×tan(|γ 2i -τ'|),

[0157] Among them, L 1i is the length of the i-th first dummy electrode 112 in the first finger electrode 110, γ 2i is the angle between the tangent line of the second gap track at the i-th first fake finger electrode 112 and the second reference axis, and τ' is the reference energy flow angle.

[0158] Specifically, the length of the second dummy electrode 122 satisfies the following conditions:

[0159] L 2i ≥5λ×tan(|γ 1i -τ'|);

[0160] 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.

[0161] Within a certain range, the longer the length of the pseudo-finger electrode is, the less the acoustic wave leakage is. Therefore, in some embodiments, the length of the first pseudo-finger 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 pseudo-finger 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 finger electrode is, the greater the resistance will be, thereby increasing the power consumption of the device. Therefore, the length of the dummy finger electrode should not be too long.

[0162] 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, Figure 6 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 2 ,like Figure 6As shown, the tangent direction of the first gap track is the same as that of the second gap track, and the first gap track is parallel to the second gap track.

[0163] In the embodiment of the present application, by adopting a suitable gap track tangent, the energy flow direction is not completely coincident with the gap track tangent, thereby suppressing the lateral high-order mode in the acoustic resonator. In addition, due to the difference in energy flow direction between the target acoustic mode and the parasitic mode, the target acoustic 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 mode will not drop excessively.

[0164] In the 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 extending direction of the reflective grid 130 electrode and the sound wave propagation direction have a preset angle. In some embodiments, the extending direction of the reflective grid 130 electrode can be perpendicular to the sound wave propagation direction. Figure 2 As shown, the top electrode 10 further includes a first reflection grating 131 and a second reflection grating 132. The first reflection grating 131 and the second reflection grating 132 are respectively disposed on both sides of a preset number of interdigital electrode pairs, ie, both sides of the first finger electrode 110 and the second finger electrode 120.

[0165] 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, and 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, etc.

[0166] As an optional implementation, the bottom electrode 30 is a surface electrode. Fig.10 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 2 ,like Fig.10 As shown, the acoustic wave resonator comprises a bottom electrode 30, a piezoelectric film 20 and a top electrode 10 which are arranged in sequence from bottom to top. The bottom electrode 30 may be a surface electrode.

[0167] As another optional implementation, the bottom electrode 30 is an interdigitated electrode. Fig.11 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 3 ,like Fig.11As shown, the acoustic wave resonator includes a bottom electrode 30, a piezoelectric film 20 and a top electrode 10 arranged in sequence from bottom to top. The bottom electrode 30 may be a forked electrode, wherein the electrode fingers of the bottom electrode 30 correspond one-to-one to the electrode fingers of the top electrode 10.

[0168] In some 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, Fig.12 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 4 ,like Fig.12 As shown, 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 may be a surface electrode.

[0169] In some other optional embodiments, at least one intermediate dielectric layer 50 is further disposed between the piezoelectric film 20 and the supporting substrate 40 . Fig.13 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 5 ,like Fig.13 As shown, 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 arranged in sequence from bottom to top. Among them, the bottom electrode 30 can be a forked electrode. The function of the intermediate dielectric layer 50 can be used to accelerate the heat dissipation of the acoustic wave resonator, or to reduce the power consumption of the acoustic wave resonator, or to perform temperature compensation on the radio frequency signal. 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 lithium tantalate or lithium niobate, the intermediate dielectric layer 50 is silicon oxide, and the supporting substrate 40 is sapphire, quartz or silicon carbide. As another example, the piezoelectric film 20 is lithium tantalate or lithium niobate, the intermediate dielectric layer 50 is silicon oxide and polycrystalline silicon, and the supporting substrate 40 is silicon.

[0170] In the above embodiment, the acoustic wave resonator may not include the supporting substrate 40 , that is, the piezoelectric film 20 is directly disposed on the intermediate dielectric layer 50 . Fig.14 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 6 ,like Fig.14As shown, the acoustic wave resonator includes an intermediate dielectric layer 50, a piezoelectric film 20 and a top electrode 10 which are arranged in sequence from bottom to top.

[0171] In some other optional embodiments, a Bragg reflection layer 60 may be further disposed between the piezoelectric film 20 and the supporting substrate 40 . Fig.15 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 7 ,like Fig.15 As shown, the acoustic wave resonator includes a supporting substrate 40, a Bragg reflection layer 60, a piezoelectric film 20 and a top electrode 10 which are arranged in sequence from bottom to top.

[0172] In the embodiment of the present application, the area corresponding to the first electrode finger 111 and the second gap track and the area corresponding to the second electrode finger 121 and the first gap track are provided with a load structure 70. 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, so that the sound wave can more easily 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.

[0173] As an optional implementation, Fig.16 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 3 ,like Fig.16 As shown, in the acoustic wave resonator, a load block 71 is provided in the air gap region, and 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 can be provided integrally with the first electrode finger 111 and / or the second electrode finger 121. The added load block 71 can reduce the sound velocity in the air gap region, making it easier for the sound wave energy to enter the pseudo-finger electrode region, which is beneficial to the suppression of the lateral mode.

[0174] As another optional implementation, Fig.17 A schematic diagram of the structure of a top electrode provided in an embodiment of the present application Figure 4 ,like Fig.17As shown, 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 can be provided integrally with the first electrode finger 111 and / or the second electrode finger 121. The added load bar 72 can reduce the sound velocity in the air gap region, making it easier for the sound wave energy to enter the pseudo-finger electrode region, which is beneficial to the suppression of the lateral mode.

[0175] 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 a strong in-plane anisotropy, which means that the electromechanical coupling coefficient can be adjusted by changing the in-plane acoustic wave propagation direction, but in this process, the energy flow angle is inevitably not 0, so it is stipulated that the average angle between the tangent direction of the gap trajectory and the acoustic wave energy flow direction does not exceed 15°, and the maximum angle is not less than 1°.

[0176] The acoustic resonator described in the embodiment of the present application utilizes the in-plane anisotropy of the single crystal piezoelectric material to adjust the electromechanical coupling coefficient. To achieve this process, 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, with the change of the in-plane acoustic wave propagation direction, due to the excessive angle between the energy flow direction and the waveguide boundary determined by the air gap, the acoustic wave energy will leak to the bus bar, which will lead to a decrease in the Q value of the device. Therefore, the angle between the trajectory of the air gap and the energy flow direction is restricted. The angle between the energy flow direction and the tangent of the gap trajectory at the i-th pair of interdigital electrodes, that is, the energy flow incident angle at the i-th pair of interdigital electrodes, is stipulated to be not less than 1°, which can play a role in suppressing the lateral high-order mode. In addition, as the energy flow angle increases, the corresponding angle between the tangent 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 Q value of the target acoustic wave mode. The scheme 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. It can also be used to suppress parasitic modes inside and outside the band.

[0177] An embodiment of the present application also provides an acoustic wave filter, which includes at least one acoustic wave resonator as described above.

[0178] 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.

[0179] In some optional embodiments, the acoustic wave filter may include two or more 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 sound wave propagation direction angle θ in at least one acoustic wave resonator is different from the sound wave propagation direction angle θ in other acoustic wave resonators. In other embodiments, in the acoustic wave resonators proposed in two or more above embodiments, the sound wave propagation direction angle θ of all acoustic wave resonators is different from each other.

[0180] 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 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. 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.

[0181] 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 is convenient for multi-zero point design, so that the acoustic wave filter has a flatter passband.

[0182] An embodiment of the present application also provides an acoustic wave filter module, which includes the acoustic wave filter as described above.

[0183] 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 .

[0184] 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: (FBWmax -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 It is the minimum relative bandwidth of the acoustic wave filter in the acoustic wave filter module.

[0185] 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.

[0186] Embodiment 1:

[0187] Fig.18 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 8 ,like Fig.18 As shown, the acoustic wave resonator in this embodiment includes a supporting substrate 40, an intermediate dielectric layer 50, a piezoelectric film 20 and a top electrode 10 from bottom to top. Among them, the material of the supporting substrate 40 is sapphire, the intermediate dielectric layer 50 is silicon oxide, and the thickness of the intermediate dielectric layer 50 is 500nm. The piezoelectric film 20 is Y42-cut lithium tantalate, the thickness of the piezoelectric film 20 is 560nm, and the top electrode 10 is titanium / aluminum / titanium, and the thicknesses are 2nm / 120nm / 3nm respectively. The first reference axis is the crystal X axis.

[0188] like Figure 2 or Figure 6 As shown, 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 dummy electrodes. Among the interdigitated electrode pairs, 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 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 wave 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 will 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.

[0189] Fig.19 A schematic diagram of the change of the acoustic wave energy flow direction and the tangent direction of the gap trajectory of an acoustic wave resonator proposed in an embodiment of the present application with the angle θ of the acoustic wave propagation direction, as shown in FIG. Fig.19As shown, no matter what value the sound wave propagation direction angle θ takes, the angle between the sound wave energy flow direction and the tangent direction of the gap trajectory is kept within 15°.

[0190] Fig. 20 A method provided in the embodiment of the present application Figure 6 The corresponding Q value Qp at the anti-resonance frequency for different gap trajectory tangential angles γ and different sound wave propagation direction angles θ is as follows: Fig. 20 As shown in the figure, it can be seen that when γ-θ is at 7° or γ-θ is near -6°, the Q value of the acoustic wave resonator remains above 3000, and the highest even exceeds 5000. This is because, according to Figure 4 The results shown in the figure show that when γ-θ is at 7° or γ-θ is near -6°, the energy inflow incident angle η is small, and a small amount of energy leaks into the pseudo-finger electrode, which suppresses the lateral high-order mode near the anti-resonance frequency. At the same time, the energy incident angle η is not large enough to cause the target acoustic wave mode to leak into the bus bar, so the Q value is 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.

[0191] Fig.21 The electromechanical coupling coefficients k2 and Qp corresponding to different sound wave propagation direction angles θ extracted from another set of experimental results provided in the embodiment of the present application are as follows: Fig.21 As shown in the figure, 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. Especially when the sound wave propagation direction angle θ is greater than 10°, γ-θ=6° or γ-θ=7° has a very obvious effect on improving the Q value.

[0192] Fig. 22 The admittance curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ=20° is provided in an embodiment of the present application, such as Fig. 22 As shown in the figure, it can be seen that when γ-θ = 7°, compared with γ = 0°, the admittance ratio of the target acoustic wave mode is significantly improved, and the admittance ratios 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 are all reduced.

[0193] Fig.23 The impedance phase curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ=20° is provided in an embodiment of the present application, such as Fig.23 As shown in the figure, it can be seen 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 are all reduced. It shows that the solution proposed in the embodiment of the present application can improve the Q value of the target acoustic wave mode while weakening the parasitic mode.

[0194] Fig.24 The Bode-Q curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ=20° is provided in the embodiment of the present application. Fig.24 As shown in the figure, it can be seen that when γ-θ=7°, the Q value of the target acoustic wave mode is greatly improved compared with γ=0°.

[0195] Fig.25 A method provided in the embodiment of the present application Fig.17 The corresponding target acoustic wave mode vibration shape diagram when the acoustic wave propagation direction angle θ = 20° and γ-θ = 7° is as follows: Fig.25 As shown in the figure, it can be seen that although the direction of sound wave propagation rotates 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 sound wave energy is basically concentrated in the interdigital electrode area, ensuring a higher Q value.

[0196] Fig.26 The admittance and conductance curves of the acoustic wave resonator when the acoustic wave propagation direction angle θ=0° and γ=0° are provided in an embodiment of the present application, such as Fig.26 As shown in the figure, it can be seen that there are transverse high-order modes between the resonant frequency and the anti-resonant frequency.

[0197] Fig. 27 The admittance and conductance curves of the acoustic wave resonator when the acoustic wave propagation direction angle θ=20° and γ-θ=7° are provided in an embodiment of the present application, such as Fig. 27 As shown in the figure, it can be seen that the transverse high-order mode between the resonant frequency and the anti-resonant frequency is basically suppressed, and the energy inflow incident angle at this time is about 7°. Therefore, a smaller energy inflow incident angle can suppress the transverse high-order mode.

[0198] Fig.28 A schematic diagram of the displacement distribution of a lateral 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 is provided in an embodiment of the present application, as shown in FIG. Fig.28 As shown, 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 electrode. 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 sound wave is concentrated in the overlapping area of ​​the forked electrode, and a sinusoidal distribution appears, and the molecular integral is not 0. When the energy inflow incident angle η is moderate, the sound wave leaks to the pseudo-finger electrode, but does not leak to the bus bar area. At this time, due to the change in 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.

[0199] In this embodiment, an acoustic wave filter can be obtained by connecting the above acoustic wave resonators in series and in parallel.

[0200] Fig.29 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 1 Table 1 is the parameter table of the acoustic wave filter. Fig.29 As shown in the figure, 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, in order to reduce the bandwidth, the acoustic wave resonator generally has a larger acoustic wave propagation direction angle θ.

[0201] Table 1 Parameters of an acoustic wave filter Table 1

[0202]

[0203] Fig.30 The admittance curve and 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 are as follows: Fig.30 As shown in the figure, it can be seen 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.

[0204] Fig.31 Table 1 is an S parameter curve corresponding to the acoustic wave filter provided in the embodiment of the present application, such as Fig.31 As shown in the figure, it can be seen that despite the large sound wave propagation direction angle θ, the insertion loss of the acoustic wave filter is about 1.07 dB and the relative bandwidth is about 2.55%.

[0205] Fig.32 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 2 Table 2 is the parameter table of the acoustic wave filter. Fig.32 As shown in the figure, 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, and the target bandwidth is larger.

[0206] Table 2 Parameters of an acoustic wave filter Table 2

[0207]

[0208] Fig.33 The S21 curve corresponding to the acoustic wave filter shown in Table 1 and Table 2 provided in the embodiment of the present application is as follows: Fig.33As shown, the bandwidths of the two acoustic wave filters are 50MHz and 68MHz, the relative bandwidths are 2.55% and 3.47%, and the insertion losses are 1.07dB and 0.77dB, respectively. The two acoustic wave filters have lower insertion losses and different relative bandwidths. This proves the feasibility of implementing acoustic wave filters with different relative bandwidths on the same piezoelectric substrate using the embodiment of the present application.

[0209] Fig.34 Table 3 is a schematic diagram of the structure of a comparative acoustic wave filter, and Table 4 is a parameter table of the acoustic wave filter. Fig.30 As shown in the figure, 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.

[0210] Table 3 Parameters of a comparative acoustic wave filter

[0211]

[0212]

[0213] Fig.35 Table 3 is the S parameter curve corresponding to the acoustic wave filter, such as Fig.30 As shown in the figure, it can be seen that due to the large incident angle η of the energy flow, the insertion loss of the acoustic wave filter reaches 2.22dB.

[0214] Fig.36 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 3 Table 4 is the parameter table of the acoustic wave filter. Fig.36 As shown in the figure, 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.

[0215] Table 4 Parameters of an acoustic wave filter Table 3

[0216]

[0217] Fig.37 Table 4 is an S parameter curve corresponding to the acoustic wave filter provided in the embodiment of the present application, such as Fig.37 As shown in the figure, it can be seen 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.

[0218] Fig.38 The S21 curve corresponding to the acoustic wave filter shown in Table 3 and Table 4 provided in the embodiment of the present application is as follows: Fig.38As shown, the acoustic wave propagation directions of the acoustic wave resonators of the two acoustic wave filters are 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 air gap tangent 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.

[0219] Embodiment 2:

[0220] Fig.39 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 9 ,like Fig.39 As shown, 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. Among them, the material of the supporting substrate 40 is silicon, the material of the first intermediate dielectric layer 51 is polycrystalline silicon, and its thickness is 1 μm. The material of the second intermediate dielectric layer 52 is silicon oxide, and its thickness is 500nm. The piezoelectric film 20 is Y42-cut lithium tantalate, and its thickness is 600nm. The top electrode 10 is titanium / aluminum / titanium, and its thickness is 2nm / 120nm / 3nm respectively, and the first reference axis is the crystal X axis.

[0221] Fig.40 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 the embodiment of the present application is as follows: Fig.40 As shown in the figure, it can be seen 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.

[0222] Fig.41 The admittance curve of the acoustic wave resonator provided in the 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°, Fig.42 The Bode-Q curve of the acoustic wave resonator provided in the 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°, as shown in FIG. Fig.41 and Fig.42 As shown in the figure, it can be seen 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.

[0223] Fig.43 The admittance curve of the acoustic wave resonator provided in the embodiment of the present application is a graph showing that γ is 0°, the acoustic wave propagation direction angle θ=0° and the acoustic wave propagation direction angle θ=20°. Fig.44 The Bode-Q curve of the acoustic wave resonator provided in the embodiment of the present application is as follows: Fig.43 and Fig.44 As shown in the figure, it can be seen that when the sound wave propagation direction angle θ=20° is relative to the sound wave propagation direction angle θ=0°, the Q value decreases significantly due to the increase in the energy inflow incident angle.

[0224] Fig.45 The electromechanical coupling coefficients k2 and Qp corresponding to different sound wave propagation direction angles θ extracted from another set of experimental results provided in the embodiment of the present application are as follows: Fig.45 As shown in the figure, it can be seen that when γ-θ = 6°, the Q value of the acoustic resonator remains above 2500, and the highest exceeds 4000. When the sound wave propagation direction angle θ is greater than 10°, γ = 0° corresponds to a significant decrease in the Q value. It is proved that the energy loss of the acoustic wave can be effectively reduced by changing the tangential direction of the air gap to reduce the incident angle η of the energy flow.

[0225] Fig.46 The admittance curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ=20° is provided in an embodiment of the present application, such as Fig.46 As shown in the figure, it can be seen that when γ-θ = 6°, compared with γ = 0°, the admittance ratio of the target acoustic wave mode is significantly improved, and the admittance ratios 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 are all reduced.

[0226] Fig.47 The impedance phase curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ=20° is provided in an embodiment of the present application, such as Fig.47 As shown in the figure, it can be seen that when γ-θ=6°, 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 are all reduced. 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.

[0227] Fig.48 The Bode-Q curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ=20° is provided in the embodiment of the present application. Fig.48 As shown in the figure, it can be seen that when γ-θ=6°, the Q value of the target acoustic wave mode is greatly improved compared with γ=0°.

[0228] Table 5 is a parameter table 4 of an acoustic wave filter provided in an embodiment of the present application. Except that the piezoelectric substrate of the acoustic wave filter is different from that in Table 4, the parameters of the acoustic wave filter in Table 5 are the same as those of the acoustic wave filter in Table 4.

[0229] Table 5 Parameters of an acoustic wave filter Table 4

[0230]

[0231] Fig.49 A schematic diagram of the structure of an acoustic wave filter provided in an embodiment of the present application Figure 5 Table 6 is the parameter table of the acoustic wave filter. Fig.49 As shown in the figure, 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.

[0232] Table 6 Parameters of an acoustic wave filter Table 5

[0233]

[0234] Fig.50 The S parameter curve corresponding to the acoustic wave filter shown in Table 5 and Table 6 provided in the embodiment of the present application is as follows: Fig.50 As shown, the bandwidths of the two acoustic wave filters are 47MHz and 65MHz, the relative bandwidths are 2.47% and 3.41%, and the insertion losses are 1.05dB and 0.9dB, respectively. The two acoustic wave filters have lower insertion losses and different relative bandwidths. This proves the feasibility of implementing acoustic wave filters with different relative bandwidths on the same piezoelectric substrate using the embodiment of the present application.

[0235] Embodiment 3:

[0236] Fig.51 A schematic diagram of the structure of an acoustic wave resonator provided in an embodiment of the present application Figure 10 , such as Fig.51 As shown, the acoustic wave resonator includes a supporting substrate 40, a piezoelectric film 20 and a top electrode 10 from bottom to top. 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 Y axis.

[0237] Fig.52 The electromechanical coupling coefficient k2 of an acoustic wave resonator provided in an embodiment of the present application, the energy flow angle τ of the target acoustic wave mode and the parasitic mode change with the acoustic wave propagation direction angle θ, such as Fig.52As shown in the figure, when the acoustic wave propagation direction angle θ=167°, the electromechanical coupling coefficient of the target acoustic wave mode SH0 mode reaches the maximum, and 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%.

[0238] Fig.53 The admittance curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ is 157°, γ=0° and γ=-20° is provided in the embodiment of the present application. Fig.53 As shown, when γ = -20° compared to γ ​​= 0°, the admittance ratio of the target acoustic 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 mode is still within 15°.

[0239] Fig.54 The impedance phase curve of the acoustic wave resonator when the acoustic wave propagation direction angle θ is 157°, γ=0° and γ=-20° is provided in the embodiment of the present application, as shown in FIG. Fig.54 As shown in FIG. 1 , when γ=-20°, the phase amplitude of the Rayleigh mode is significantly reduced compared to when γ=0°. Therefore, the parasitic mode can be suppressed by making the parasitic mode and the target acoustic wave mode have different energy flow directions.

[0240] In view of the problem that it is difficult to adjust the electromechanical coupling coefficient of the existing acoustic wave resonator, and the problem of complicated process or increased loss in the process of adjusting the electromechanical coupling coefficient, the embodiment of the present application proposes to use a single crystal piezoelectric film with strong in-plane anisotropy, and to adjust the electromechanical coupling coefficient by changing the in-plane acoustic wave propagation direction of the acoustic wave, and at the same time control the angle between the tangent of the gap track and the energy flow direction of the target acoustic wave mode, so as to avoid energy leakage caused by excessive energy flow incident angle. Acoustic wave resonators with different electromechanical coupling coefficients are realized on the same piezoelectric film, and then acoustic wave filters with different relative bandwidths are realized. 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 of the gap track is not completely parallel to the energy flow direction of the target acoustic wave mode to suppress the lateral high-order mode. In addition, by selecting a suitable in-plane direction, the energy flow direction of the out-of-band parasitic mode can also be made to have a large difference from the energy flow direction of the target acoustic wave mode, so that the out-of-band parasitic mode can be leaked to the bus bar area while maintaining the high Q value of the target acoustic wave mode, thereby improving the out-of-band suppression level.

[0241] It should be noted that the above-mentioned sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above-mentioned specific embodiments of this specification are described. Other embodiments are within the scope of the attached claims. In some cases, the actions or steps recorded 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 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.

[0242] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0243] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0244] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope 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 comprises 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 comprises 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 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; 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 tangent angle, and the angle between the average tangent of the second gap trajectory and the second reference axis is the second gap trajectory tangent angle. The first gap trajectory tangent angle and the second gap trajectory tangent 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 k2 is the maximum value of the electromechanical coupling coefficient when the sound wave propagates in different directions. 30° is the electromechanical coupling coefficient after the crystal axis orientation is rotated 30° relative to the maximum electromechanical coupling value.

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

10. The acoustic wave resonator according to claim 1, characterized in that 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 is parallel to the second gap track.

12. The acoustic wave resonator according to claim 1, characterized in that The distance between adjacent first electrode fingers and the distance between adjacent second electrode fingers are both λ; 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.

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, characterized in that 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.

16. The acoustic wave resonator according to claim 1, characterized in that 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, characterized in that 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, characterized in that 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 disposed 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, polycrystalline silicon, and amorphous silicon.

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

24. The acoustic wave resonator according to claim 1, characterized in that A load structure is provided in an area corresponding to the first electrode finger and the second gap track, and in an area corresponding to the second electrode finger and the first gap track.

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 comprises at least one acoustic wave resonator according to any one of claims 1 to 25.

27. The acoustic wave filter according to claim 26, characterized in that 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, characterized in that At least two of the 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 as described in any one of claims 26 to 28.

30. The acoustic wave filter module according to claim 29, characterized in that: The acoustic wave filter module includes at least two acoustic wave filters, and 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, characterized in that: 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 is the maximum relative bandwidth of the acoustic wave filter in the acoustic wave filter module, FBW min It is the minimum relative bandwidth of the acoustic wave filter in the acoustic wave filter module.

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