An acoustic resonator, an acoustic filter and an acoustic filter module

Abstract

This application relates to the field of semiconductor technologies, and particularly to an acoustic resonator, an acoustic wave filter, and an acoustic wave filter module. The acoustic resonator at least includes: a piezoelectric thin film and interdigital electrodes; taking a preset crystal axis in the piezoelectric thin film as a first reference axis and the normal direction of the interdigital electrode pair as a second reference axis, there is a preset included angle between the first reference axis and the second reference axis; the average tangential direction of the first gap trajectory in the interdigital electrodes satisfies a preset condition with the average tangential direction of the second gap trajectory. By changing the acoustic wave propagation direction within the acoustic wave plane, the electromechanical coupling coefficient of the acoustic resonator is adjusted. Moreover, by designing the tangential angle of the first gap trajectory and the tangential angle of the second gap trajectory, while changing the electromechanical coupling coefficient of the acoustic resonator, energy leakage caused by an excessive incident angle of energy is avoided. Therefore, acoustic resonators with different electromechanical coupling coefficients can be realized on the same piezoelectric thin film, and then acoustic wave filters with different relative bandwidths can be realized.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and particularly to an acoustic resonator, an acoustic filter, and an acoustic filter module. Background Art

[0002] With the development of mobile communication systems, the number of acoustic filters in the radio frequency front end is increasing. For example, the number of acoustic filters in a smart phone has increased to 50 or even more than 100. Acoustic filters in different frequency bands generally have different frequencies and bandwidths. In addition, there are some frequency bands with close frequencies but significantly different bandwidths. For example, Band 3, Band 4, and Band 9 have operating frequencies all between 1.7 and 1.8 GHz, but their bandwidths are 75 MHz, 45 MHz, and 35 MHz respectively. Acoustic filters in different frequency bands have different requirements for the frequency and electromechanical coupling coefficient of the acoustic resonators that make up the acoustic filters.

[0003] Currently, for the acoustic resonators that make up acoustic filters in a specific frequency band, they are often realized through specific material structures. For example, for bulk acoustic wave (BAW) devices based on aluminum nitride thin films, different relative bandwidths need to be achieved by different scandium doping concentrations. In addition, the thickness of the piezoelectric thin film needs to be changed to achieve different operating frequencies. For surface acoustic wave (SAW) devices based on piezoelectric hetero-substrates, the required frequency is satisfied 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, specific material structures or compositions need to be designed. This situation causes great trouble both for the production and processing of materials and for the preparation of acoustic devices, restricting the large-scale application of acoustic devices. Summary of the Invention

[0004] To solve the above technical problems, this application proposes an acoustic resonator, an acoustic filter, and an acoustic filter module.

[0005] On the one hand, an embodiment of this application proposes an acoustic resonator, including: a piezoelectric thin film and a top electrode disposed on the first surface of the piezoelectric thin film;

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

[0007] The first finger-shaped electrode includes a preset number of first electrode finger bars and a first dummy finger electrode, and the first electrode finger bars and the first dummy finger electrode are arranged at intervals;

[0008] The second finger-shaped electrode includes a preset number of second electrode fingers and second dummy finger electrodes, and the second electrode fingers and the second dummy finger electrodes are arranged at intervals;

[0009] The first electrode fingers and the second electrode fingers are arranged in a cross pattern, and adjacent first electrode fingers and second electrode fingers form interdigital electrode pairs;

[0010] The first electrode fingers and the second dummy finger electrodes are arranged opposite to each other, and a first gap track is formed between the first electrode fingers and the second dummy finger electrodes;

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

[0012] Taking the preset crystal axis in the piezoelectric thin film as the first reference axis and the normal direction of the interdigital electrode pair as the second reference axis, there is a preset included angle between the first reference axis and the second reference axis;

[0013] The included angle between the average tangential direction of the first gap track and the second reference axis is the tangential angle of the first gap track, and the included angle between the average tangential direction of the second gap track and the second reference axis is the tangential angle of the second gap track. The tangential angle of the first gap track and the tangential angle of the second gap track satisfy a preset condition.

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

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

[0016] where k2 max is the maximum value of the electromechanical coupling coefficient when the acoustic wave propagation direction is different, and k2 30° is the electromechanical coupling coefficient after rotating 30° with respect to the crystal axis orientation of the maximum electromechanical coupling.

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

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

[0019] The angle of the preset included angle is 0° to 45°, or 130° to 180°.

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

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

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

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

[0024]

[0025] Wherein, is the tangential angle of the first gap trajectory, and τ’ is the reference energy flow angle;

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

[0027]

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

[0029] In some alternative embodiments, the tangent of the first gap trajectory at any of the first electrode fingers and the included angle between the third reference axis is the first energy incident angle, and the tangent of the second gap trajectory at any of the second electrode fingers and the included angle between the third reference axis is the second energy incident angle. The maximum value of at least one first energy incident angle or the maximum value of at least one second energy incident angle is greater than or equal to 1°.

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

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

[0032] L 1i ≥5λ×tan(|γ 2i -τ’|),

[0033] Wherein, L 1i is the length of the i-th first dummy finger electrode in the first finger-shaped electrode, γ 2i is the included angle between the tangent of the second gap trajectory at the i-th first dummy finger electrode and the second reference axis, and τ’ is the reference energy flow angle;

[0034] The length of the second dummy finger electrode satisfies the following conditions:

[0035] L 2i ≥5λ×tan(|γ 1i -τ’|);

[0036] Wherein, L 2iis the length of the i-th second dummy finger electrode in the second finger-shaped electrode, γ 1i is the angle between the tangent of the first gap trajectory at the i-th second dummy finger electrode and the second reference axis, and τ' is the reference power flow angle.

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

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

[0039] In some alternative embodiments, the first gap trajectory and the second gap trajectory are parallel.

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

[0041] The length of the cross-region between the first electrode finger and the second electrode finger in the interdigital electrode pair is 5λ to 40λ.

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

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

[0044] In some alternative embodiments, the top electrode further includes a first reflective grating and a second reflective grating, and the first reflective grating and the second reflective grating are respectively disposed on both sides of a preset number of interdigital electrode pairs.

[0045] In some alternative embodiments, the acoustic wave resonator further includes a bottom electrode, and the bottom electrode is disposed on the second surface of the piezoelectric thin film, and the second surface is opposite to the first surface.

[0046] In some alternative embodiments, the bottom electrode is a planar electrode.

[0047] In some alternative embodiments, the bottom electrode is an interdigital electrode, and the electrode fingers of the bottom electrode correspond to the electrode fingers in the top electrode one by one.

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

[0049] In some alternative embodiments, the material of the support substrate is one of sapphire, silicon, spinel, silicon carbide, diamond, diamond-like, silicon nitride, boron nitride, boron carbide, quartz, germanium, aluminum nitride, silicon nitride, yttrium aluminum garnet, lithium tantalate, lithium niobate.

[0050] In some alternative embodiments, at least one intermediate dielectric layer is further disposed between the piezoelectric thin film and the support substrate.

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

[0052] In some alternative embodiments, a Bragg reflector layer is further disposed between the piezoelectric thin film and the support substrate.

[0053] In some alternative embodiments, a load structure is provided in the region where the first electrode finger corresponds to the second gap track and the region where the second electrode finger corresponds to the first gap track.

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

[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 alternative embodiments, the acoustic wave filter includes at least two acoustic wave resonators as described above;

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

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

[0059] The average angle of the tangential angle of the first gap track and the tangential angle of the second gap track in the series acoustic wave resonator is greater than the average angle of the tangential angle of the first gap track and the tangential angle of the second gap track 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 alternative 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 thin film.

[0062] In some alternative embodiments, in the acoustic wave filter module, the maximum relative bandwidth and the minimum relative bandwidth of the acoustic wave filter satisfy the following conditions:

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

[0064] Wherein, FBW max is the maximum relative bandwidth of the acoustic wave filter in the acoustic wave filter module, and FBW minis the minimum relative bandwidth of the acoustic wave filter in the acoustic wave filter module.

[0065] The technical solutions provided by the embodiments of the present application have the following technical effects:

[0066] For the acoustic wave resonator, acoustic wave filter, and acoustic wave filter module described in the embodiments of the present application, a single-crystal piezoelectric thin film with in-plane anisotropy is utilized. By designing a preset angle between the interdigital electrode pair and a preset crystal axis in the piezoelectric thin film, the in-plane acoustic wave propagation direction is changed, so as to adjust the electromechanical coupling coefficient of the acoustic wave resonator. Moreover, by designing the first gap trajectory tangential angle and the second gap trajectory tangential angle, while changing the electromechanical coupling coefficient of the acoustic wave resonator, energy leakage caused by an excessive incident energy angle is avoided. Therefore, acoustic wave resonators with different electromechanical coupling coefficients can be realized on the same piezoelectric thin film, and then acoustic wave filters with different relative bandwidths can be realized. In addition, by selecting an appropriate in-plane acoustic wave propagation direction, the energy flow angle of the target acoustic wave mode propagating in the acoustic wave resonator has a large difference from the energy flow angle of the out-of-band parasitic mode. Together with an appropriate gap trajectory tangential angle, 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. 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 following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0068] Figure 1 is a structural schematic diagram of an acoustic wave resonator provided by an embodiment of the present application Figure 1 ;

[0069] Figure 2 is a structural schematic diagram of a top electrode provided by an embodiment of the present application Figure 1 ;

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

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

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

[0073] Figure 6 Structural schematic of a top electrode provided by an embodiment of the present application Figure 2 ;

[0074] Figure 7 is Figure 6 Admittance curves corresponding to θ = 0° and θ = 20°, where γ is 0° in both cases;

[0075] Figure 8 is Figure 6 Bode-Q curves corresponding to θ = 0° and θ = 20°, where γ is 0° in both cases;

[0076] Figure 9 is Figure 6 Main mode vibration mode diagram corresponding to θ = 20°, where γ is 0°;

[0077] Figure 10 Structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 2 ;

[0078] Figure 11 Structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 3 ;

[0079] Figure 12 Structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 4 ;

[0080] Figure 13 Structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 5 ;

[0081] Figure 14 Structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 6 ;

[0082] Figure 15 Structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 7 ;

[0083] Figure 16 Structural schematic of a top electrode provided by an embodiment of the present application Figure 3 ;

[0084] Figure 17 Structural schematic of a top electrode provided by an embodiment of the present application Figure 4 ;

[0085] Figure 18 Structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 8 ;

[0086] Figure 19 Schematic diagram showing the variation of the acoustic energy flow direction and the tangential direction of the gap trajectory with the acoustic propagation direction angle θ for the acoustic resonator provided in the embodiment of the present application;

[0087] Figure 20 One provided by the embodiment of the present application Figure 6 Q value Qp at the anti-resonant frequency corresponding to different tangential angles γ of the gap trajectory and different acoustic propagation direction angles θ;

[0088] Figure 21 Electromechanical coupling coefficient k2 and Qp corresponding to different acoustic propagation direction angles θ extracted from another set of experimental results provided by the embodiment of the present application;

[0089] Figure 22 Admittance curve of the acoustic resonator when the acoustic propagation direction angle θ = 20° provided by the embodiment of the present application;

[0090] Figure 23 Impedance phase curve of the acoustic resonator when the acoustic propagation direction angle θ = 20° provided by the embodiment of the present application;

[0091] Figure 24 Bode-Q curve of the acoustic resonator when the acoustic propagation direction angle θ = 20° provided by the embodiment of the present application;

[0092] Figure 25 One provided by the embodiment of the present application Figure 17 Target acoustic mode vibration pattern when the acoustic propagation direction angle θ = 20° and γ - θ = 7°;

[0093] Figure 26 Admittance and conductance curves of the acoustic resonator when the acoustic propagation direction angle θ = 0° and γ = 0° provided by the embodiment of the present application;

[0094] Figure 27 Admittance and conductance curves of the acoustic resonator when the acoustic propagation direction angle θ = 20° and γ - θ = 7° provided by the embodiment of the present application;

[0095] Figure 28 Schematic diagram of the displacement distribution of the transverse high-order mode corresponding to too small an incident angle η of the energy flow, a suitable incident angle η of the energy flow, and too large an incident angle η of the energy flow provided by the embodiment of the present application;

[0096] Figure 29 Structural schematic corresponding to the acoustic filter provided by the embodiment of the present application Figure 1 ;

[0097] Figure 30The admittance curves and Bode-Q curves of each acoustic resonator corresponding to an acoustic wave filter shown in Table 1 provided by an embodiment of the present application;

[0098] Figure 31 The S-parameter curves corresponding to an acoustic wave filter shown in Table 1 provided by an embodiment of the present application;

[0099] Figure 32 The structural schematic diagram corresponding to an acoustic wave filter provided by an embodiment of the present application Figure 2 ;

[0100] Figure 33 The S21 curves corresponding to the acoustic wave filters shown in Table 1 and Table 2 provided by an embodiment of the present application;

[0101] Figure 34 The structural schematic diagram of a comparative acoustic wave filter;

[0102] Figure 35 The S-parameter curves corresponding to the acoustic wave filter in Table 3;

[0103] Figure 36 The structural schematic diagram corresponding to an acoustic wave filter provided by an embodiment of the present application Figure 3 ;

[0104] Figure 37 The S-parameter curves corresponding to the acoustic wave filter in Table 4 provided by an embodiment of the present application;

[0105] Figure 38 The S21 curves corresponding to the acoustic wave filters shown in Table 3 and Table 4 provided by an embodiment of the present application;

[0106] Figure 39 The structural schematic diagram of an acoustic resonator provided by an embodiment of the present application Figure 9 ;

[0107] Figure 40 The Q value Qp at the anti-resonant frequency corresponding to different gap track tangential angles γ and different acoustic wave propagation direction angles θ provided by an embodiment of the present application;

[0108] Figure 41 The admittance curve diagrams of an acoustic resonator when the acoustic wave propagation direction angle θ = 0° and γ = -5°, and when the acoustic wave propagation direction angle θ = 4° and γ = 10° provided by an embodiment of the present application;

[0109] Figure 42 The Bode-Q curve diagrams of an acoustic resonator when the acoustic wave propagation direction angle θ = 0° and γ = -5°, and when the acoustic wave propagation direction angle θ = 4° and γ = 10° provided by an embodiment of the present application;

[0110] Figure 43The admittance curves of a SAW resonator when γ is 0°, the acoustic wave propagation direction angle θ = 0° and the acoustic wave propagation direction angle θ = 20°, provided by an embodiment of the present application;

[0111] Figure 44 The Bode-Q curves of a SAW resonator when γ is 0°, the acoustic wave propagation direction angle θ = 0° and the acoustic wave propagation direction angle θ = 20°, provided by an embodiment of the present application;

[0112] Figure 45 The electromechanical coupling coefficient k2 and Qp corresponding to different acoustic wave propagation direction angles θ extracted from another set of experimental results, provided by an embodiment of the present application;

[0113] Figure 46 The admittance curves of a SAW resonator when the acoustic wave propagation direction angle θ = 20°, provided by an embodiment of the present application;

[0114] Figure 47 The impedance phase curves of a SAW resonator when the acoustic wave propagation direction angle θ = 20°, provided by an embodiment of the present application;

[0115] Figure 48 The Bode-Q curves of a SAW resonator when the acoustic wave propagation direction angle θ = 20°, provided by an embodiment of the present application;

[0116] Figure 49 The structural schematic diagram of a SAW filter provided by an embodiment of the present application Figure 5 ;

[0117] Figure 50 The S-parameter curves of the SAW filter shown in Table 5 and Table 6 provided by an embodiment of the present application;

[0118] Figure 51 The structural schematic diagram of a SAW resonator provided by an embodiment of the present application Figure 10 ;

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

[0120] Figure 53 The admittance curves of a SAW resonator when the acoustic wave propagation direction angle θ is 157°, γ = 0° and γ = -20°, provided by an embodiment of the present application;

[0121] Figure 54 The impedance phase curves of a SAW resonator when the acoustic wave propagation direction angle θ is 157°, γ = 0° and γ = -20°, provided by an embodiment of the present application.

[0122] The following provides supplementary explanations for the attached drawings:

[0123] 10 - top electrode; 110 - first finger-shaped electrode; 111 - first electrode finger bar; 112 - first dummy finger electrode; 113 - first bus bar; 120 - second finger-shaped electrode; 121 - second electrode finger bar; 122 - second dummy finger electrode; 123 - second bus bar; 130 - reflection grating; 131 - first reflection grating; 132 - second reflection grating; 20 - piezoelectric thin 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. Specific implementation manners

[0124] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0125] It should be noted that the "one embodiment" or "embodiment" referred to in the specification of the embodiments of the present application means specific features, structures or characteristics that may be included in at least one implementation manner of the present application. It should be understood that in the specification, claims and the above-mentioned drawings of the embodiments of the present application, the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings. It 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 to 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 specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances 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 this embodiment, unless otherwise specified, the meaning of "a plurality" is two or more. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system or product that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0126] In order to make the purpose, technical solutions and advantages of the disclosure of the embodiments of the present application clearer and more understandable, the following further details the embodiments of the present application in conjunction with the 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] Aiming at the problem that it is difficult for a single material system to be compatible with frequency bands of different relative bandwidths, the embodiments of the present application propose an acoustic wave resonator, an acoustic wave filter, and an acoustic wave filter module. By using a single-crystal piezoelectric thin film with in-plane anisotropy, the electromechanical coupling coefficient of the acoustic wave resonator is adjusted by changing the in-plane acoustic wave propagation direction. By adopting an appropriate gap trajectory tangential direction, while changing the electromechanical coupling coefficient of the acoustic wave resonator, energy leakage caused by an excessive energy incident angle is avoided. Therefore, acoustic wave resonators with different electromechanical coupling coefficients can be realized on the same piezoelectric thin film, and then acoustic wave filters with different relative bandwidths can be realized, thus greatly saving the production cost of materials and improving the integration degree of the acoustic wave filter. In addition, by changing the in-plane acoustic wave propagation direction to adjust the electromechanical coupling coefficient of the target acoustic wave mode, and by matching the angle between the appropriate gap trajectory 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] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of an acoustic wave resonator provided by the embodiments of the present application Figure 1 , as Figure 1 shown, the acoustic wave resonator includes: a piezoelectric thin film 20 and a top electrode 10 disposed on the first surface of the piezoelectric thin film 20.

[0129] In the embodiments of the present application, the top electrode 10 is an interdigital electrode. Figure 2 which is a schematic structural diagram of a top electrode provided by the embodiments of the present application Figure 1 , as Figure 2 shown, the top electrode 10 includes a first finger-shaped electrode 110 and a second finger-shaped electrode 120.

[0130] As Figure 2 shown, the first finger-shaped electrode 110 includes a preset number of first electrode finger bars 111 and a first dummy finger electrode 112. The roots of the first electrode finger bars 111 and the first dummy finger electrode 112 are both connected to the first bus bar 113, and the first electrode finger bars 111 and the first dummy finger electrode 112 are arranged at intervals. Optionally, in the first finger-shaped electrode 110, the number of the first electrode finger bars 111 may be the same as or different from the number of the first dummy finger electrodes 112. For example, the number of the first electrode finger bars 111 is one more than the number of the first dummy finger electrodes 112, or the number of the first electrode finger bars 111 is one less than the number of the first dummy finger electrodes 112. In the first finger-shaped electrode 110, the arrangement period of the first electrode finger bars 111 is λ. That is, the distance between two adjacent first electrode finger bars 111 is λ. Similarly, the distance between two adjacent first dummy finger electrodes 112 is also λ.

[0131] As Figure 2As shown, the second finger-shaped electrode 120 includes a preset number of second electrode fingers 121 and second dummy electrode fingers 122. The roots of the second electrode fingers 121 and the second dummy electrode fingers 122 are both connected to the second bus bar 123, and the second electrode fingers 121 and the second dummy electrode fingers 122 are arranged at intervals from each other. Optionally, in the second finger-shaped electrode 120, the number of the second electrode fingers 121 and the number of the second dummy electrode fingers 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 electrode fingers 122, or the number of the second electrode fingers 121 is one less than the number of the second dummy electrode fingers 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-shaped 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 electrode fingers 122 is also λ.

[0132] As Figure 2 shown, the first finger-shaped electrode 110 and the second finger-shaped electrode 120 have an overlapping area on the plane. In the overlapping area, the first electrode fingers 111 and the second electrode fingers 121 are arranged in a cross pattern. That is, in the overlapping area, for the non-outermost first electrode fingers 111, the second electrode fingers 121 are on both sides of them. Similarly, for the non-outermost second electrode fingers 121, the first electrode fingers 111 are on both sides of them. For an adjacent pair of the first electrode fingers 111 and the second electrode fingers 121, they form an interdigital electrode pair. Optionally, the length of the cross area between the first electrode fingers 111 and the second electrode fingers 121 in the interdigital 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 disposed opposite to the second dummy finger electrode 122, and the second electrode finger 121 is disposed opposite to the first dummy finger electrode 112. That is to say, in the top electrode 10, each first electrode finger 111 corresponds to a second dummy finger electrode 122, and similarly, each second electrode finger 121 corresponds to a first dummy finger electrode 112. For any pair of the first electrode finger 111 and the second dummy finger electrode 122 having a corresponding relationship, they do not contact each other, that is, there is a gap therebetween. Fitting the gaps between all the first electrode fingers 111 and the second dummy finger electrodes 122 having a corresponding relationship with a smooth curve, a curve can be obtained, and this curve can be called the first gap locus. Similarly, for any pair of the second electrode finger 121 and the first dummy finger electrode 112 having a corresponding relationship, they do not contact each other, that is, there is a gap therebetween. Fitting the gaps between all the second electrode fingers 121 and the first dummy finger electrodes 112 having a corresponding relationship with a smooth curve, a curve can be obtained, and this curve can be called the second gap locus.

[0134] For a surface acoustic wave resonator, the acoustic wave propagation direction corresponding to the target acoustic wave mode for transmitting an acoustic wave in its piezoelectric thin film 20 is perpendicular to the extending direction of the interdigital electrode pair. In other words, the acoustic wave propagation direction is perpendicular to the axis of the first electrode finger 111 or the second electrode finger 121, or the acoustic wave propagation direction is parallel to the normal of the interdigital pair. The included angle between the acoustic wave energy flow direction and the acoustic wave propagation direction in the surface acoustic wave resonator is the energy flow angle. In the surface acoustic wave resonator, the acoustic wave energy flow direction is the group velocity direction. Refer to Figure 2 As shown, taking the preset crystal axis in the piezoelectric thin film 20 as the first reference axis, the normal of the interdigital electrode pair as the second reference axis, and the acoustic wave energy flow direction as the third reference axis. The preset included angle between the first reference axis and the second reference axis is the acoustic wave propagation direction angle θ.

[0135] In the surface acoustic wave resonator, the included angle between the gap locus and the acoustic wave propagation direction is the gap locus tangential angle γ. When the gap locus is a curve, the included angle between the tangent of the gap locus and the acoustic wave propagation direction can be used as the gap locus tangential angle. Refer to Figure 2 As shown, the included angle between the average tangent of the first gap locus and the second reference axis is the first gap locus tangential angle The included angle between the average tangent of the second gap locus and the second reference axis is the second gap locus tangential angle The average tangential direction of the first gap trajectory refers to the average angle obtained by averaging the angles between the tangents of the first gap trajectory at each second false finger electrode 122 and the second reference axis. The line obtained by rotating the second reference axis counterclockwise by this average angle is the average tangential direction of the first gap trajectory. The average tangential direction of the second gap trajectory refers to the average angle obtained by averaging the angles between the tangents of the second gap trajectory at each first false finger electrode 112 and the second reference axis. The line obtained by rotating the second reference axis counterclockwise by this average angle is the average tangential direction of the second gap trajectory. In other words, the average tangential direction of the first gap trajectory is the line determined by the average angle of all the tangent direction angles on the first gap trajectory. The average tangential direction of the second gap trajectory is the line determined by the average angle of all the tangent direction angles on the second gap trajectory.

[0136] In addition, as shown in Figure 2 In a surface acoustic wave resonator, the angle between the gap trajectory and the acoustic energy flow direction is the incident angle of energy flow η. The angle between the second reference axis and the third reference axis is the energy flow angle τ. Representing the angle between the first reference axis and the second reference axis by the acoustic wave propagation direction angle θ, the energy flow angle τ = arctan(1 / νp × dνp / d acoustic wave propagation direction angle θ), where νp is the phase velocity corresponding to different acoustic wave propagation directions. Since the positive direction of the energy flow angle is related to the orientation of the crystal axis, it is sometimes clockwise and sometimes counterclockwise. While the tangential angle γ of the gap trajectory is always counterclockwise. Therefore, for the convenience of calculation, the positive direction of the energy flow angle and the reference positive direction of the tangential angle of the gap trajectory can be unified into the same direction, thus obtaining the reference energy flow angle τ'. The absolute value of the reference energy flow angle τ' is the same as that of the energy flow angle τ.

[0137] For a surface acoustic wave resonator, the acoustic wave propagation directions corresponding to the energy flow angles of 0 for different target acoustic wave modes are different. Figure 3 Shows the variation of the phase velocity, electromechanical coupling coefficient k2, and energy flow angle τ of a surface acoustic wave resonator with the acoustic wave propagation direction angle θ. As shown in Figure 3 When the acoustic wave propagation direction angle θ = 0°, the phase velocity and the 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 indicates 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 either. When the angle between the energy flow direction and the waveguide boundary composed of gaps is too large, it will cause the leakage of acoustic wave energy, and then lead to a decrease in the Q value of the surface acoustic wave resonator.

[0138] Figure 4 Is a schematic diagram showing the variation of the acoustic wave energy flow direction and the tangential direction of the gap trajectory of a surface acoustic wave resonator with the acoustic wave propagation direction angle θ. As shown in Figure 4 When the acoustic wave propagation direction angle θ ≠ 0°, there may be a large angle between the acoustic wave energy flow direction and the tangential direction of the gap trajectory.Figure 5 Schematic diagram of the change of the anti-resonant frequency Q value Qp of an acoustic wave resonator with the acoustic wave propagation direction angle θ. As Figure 5 shown, when the acoustic wave propagation direction angle θ increases from 0° to 4°, Qp rises. This is because the transverse high-order modes near the anti-resonant frequency are suppressed, and various existing methods for suppressing transverse high-order modes can achieve this effect. When the acoustic wave propagation direction angle θ is greater than 5°, Qp begins to decrease significantly. This is because the angle between the acoustic energy flow direction and the tangential direction of the gap trajectory is too large, that is, the incident angle η of the energy flow is too large. Therefore, simply using the method of changing the in-plane orientation to adjust the electromechanical coupling coefficient will inevitably result in a significant decrease in the Q value caused by the too large incident angle of the energy flow. Figure 7 is Figure 6 the admittance curves corresponding to θ = 0° and θ = 20°, where γ is 0° for both, Figure 8 is Figure 6 the Bode-Q curves corresponding to θ = 0° and θ = 20°, where γ is 0° for both. 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 decreases significantly. Figure 9 is Figure 6 the main mode vibration mode diagram corresponding to θ = 20°, where γ is 0°. As Figure 9 shown, it can be seen from the figure that since the angle η between the energy flow direction and the tangential direction of 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 the Q value.

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

[0140] Specifically, the piezoelectric thin film 20 in the embodiment of the present application may be a single crystal piezoelectric material with in-plane anisotropy. Optionally, the material of the piezoelectric thin film 20 may be any one of piezoelectric materials such as lithium niobate, lithium tantalate, potassium niobate, etc. Optionally, the thickness of the piezoelectric thin film 20 is 0.1λ to 1λ. Optionally, the cut type of the piezoelectric thin film is rotated Y cut, and the cut angle may be 0° to 75°. By using the in-plane anisotropy in the piezoelectric thin film 20 and designing the angle of the preset angle, that is, changing the angle θ between the acoustic wave propagation direction and the in-plane crystal axis direction of the piezoelectric thin film 20, the regulation of the electromechanical coupling coefficient of the acoustic wave resonator can be realized.

[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 is the maximum value of the electromechanical coupling coefficient at different sound wave propagation directions, and k2 30° is the electromechanical coupling coefficient after rotating 30° with respect to the crystal axis orientation relative to the maximum electromechanical coupling. Optionally, the target sound wave mode can be the 0th order horizontal shear mode, the 0th order longitudinal leaky surface acoustic wave mode, the 0th order Rayleigh mode, etc.

[0142] As an alternative implementation, the piezoelectric thin film 20 is lithium niobate or lithium tantalate of the X-cut type, the target sound wave mode in the acoustic resonator is the 0th order horizontal shear mode, and the preset crystal axis is the Y-axis. The angle of the preset included angle is 0° to 45°, or 130° to 180°. That is to say, when the piezoelectric thin film 20 is lithium niobate or lithium tantalate of the X-cut type and the target sound wave mode is the 0th order horizontal shear mode, if it is stipulated that when the sound wave propagates along the crystal Y-axis, the sound wave propagation direction angle θ = 0°, and when the sound wave propagates along the crystal Z-axis, the sound wave propagation direction angle θ = 90°, then the sound wave propagation direction angle is 0° ≤ sound wave propagation direction angle θ < 45° or 130° < sound wave propagation direction angle θ ≤ 180°.

[0143] As another alternative implementation, the piezoelectric thin film 20 is lithium niobate or lithium tantalate of the rotated Y-cut type, the target sound wave mode in the acoustic resonator is the 0th order horizontal shear mode, and the preset crystal axis is the X-axis. The angle of the preset included angle is -40° to 40°. That is to say, when the piezoelectric thin film 20 is lithium niobate or lithium tantalate, the cut type is rotated Y-cut, and the target sound wave mode is the 0th order horizontal shear mode, if it is stipulated that when the sound wave propagates along the crystal X-axis, the sound wave propagation direction angle θ = 0°, then the sound wave propagation direction range is -40° < sound wave propagation direction angle θ < 40°.

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

[0145] In the acoustic resonator, the included angle between the tangent direction of the gap trajectory and the sound wave propagation direction is γ, and the included angle between the tangent direction of the gap trajectory and the sound energy flow direction of the target sound wave mode is the energy incident angle η = γ - τ'. Therefore, the tangent direction of the gap trajectory will directly affect the magnitude of the energy incident angle. If the energy incident angle is too large, energy leakage will occur, thereby reducing the quality factor of the acoustic resonator. Therefore, in order to avoid this situation, it is necessary to design the tangents of the first gap trajectory and the second gap trajectory. That is to say, the tangent angles of the first gap trajectory and the second gap trajectory need to meet the preset conditions.

[0146] In the embodiments of the present application, taking the sound energy flow direction of the acoustic resonator as the third reference axis, the included angle between the second reference axis and the third reference axis is the reference energy flow angle;

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

[0148]

[0149] Wherein, 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 satisfies the following preset conditions:

[0151]

[0152] Wherein, 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 the embodiments 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 incident angle, and the angle between the tangent of the second gap trajectory at any second electrode finger and the third reference axis is the second energy incident angle. The maximum value of at least one first energy incident angle or the maximum value of at least one of the second energy incident angles is greater than or equal to 1°.

[0154] In the embodiments of the present application, in order to make the above-mentioned tangential angle of the gap trajectory meet the conditions, it can be achieved by setting the lengths of the first dummy finger electrode 112 and the second dummy finger electrode 122. Specifically, the angle between the average tangent of the first gap trajectory and the sound wave propagation direction is 1, the angle between the average tangent of the second gap trajectory and the sound wave propagation direction is 2, N is the number of pairs of interdigital electrodes, γi is the angle between the tangent direction of the gap trajectory at the i-th pair of interdigital electrodes and the sound wave propagation direction, then γ1i is the angle between the tangent direction of the first gap trajectory at the i-th pair of interdigital electrodes and the sound wave propagation direction, and γ2i is the angle between the tangent direction of the second gap trajectory at the i-th pair of interdigital electrodes and the sound wave propagation direction. The dummy finger electrode adjacent to the second air gap is the first dummy finger electrode 112, the length of the first dummy finger electrode 112 at the i-th pair of interdigital electrodes is L1i, and the angle between the tangent direction of the second gap trajectory at the i-th pair of interdigital electrodes and the sound wave energy flow direction is the energy incident angle η1i = |γ 2i - τ'|. The dummy finger electrode adjacent to the first air gap is the second dummy finger electrode 122, the length of the second dummy 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 sound wave energy flow direction is the energy incident angle η2i = |γ 1i - τ'|.

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

[0156] L 1i≥5λ×tan(|γ 2i - τ’|),

[0157] where L 1i is the length of the i-th first dummy finger electrode 112 in the first finger electrode 110, γ 2i is the angle between the tangent of the second gap trajectory at the i-th first dummy finger electrode 112 and the second reference axis, and τ’ is the reference power flow angle.

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

[0159] L 2i ≥5λ×tan(|γ 1i - τ’|);

[0160] where L 2i is the length of the i-th second dummy finger electrode 112 in the second finger electrode 110, γ 1i is the angle between the tangent of the first gap trajectory at the i-th second dummy finger electrode 122 and the second reference axis, and τ’ is the reference power flow angle.

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

[0162] In the embodiments of the present application, the first gap trajectory may be a straight line or a curve. Similarly, the second gap trajectory may also be a straight line or a curve. When the first gap trajectory is a straight line, the average tangential direction of the first gap trajectory is the same as the tangential direction of the gap trajectory at the i-th pair of interdigital electrodes, that is When the second gap trajectory is a straight line, the average tangential direction of the second gap trajectory is the same as the tangential direction of the gap trajectory at the i-th pair of interdigital electrodes, that is In some embodiments, the first gap trajectory and the second gap trajectory are parallel. That is, the tangential direction of the first gap trajectory is the same as the tangential direction of the second gap trajectory and remains constant, that is Figure 6 Structural schematic of a top electrode provided by an embodiment of the present application Figure 2 , such as Figure 6As shown, the tangential directions of the first gap trajectory and the second gap trajectory are the same, and the first gap trajectory is parallel to the second gap trajectory.

[0163] In the embodiments of the present application, by adopting an appropriate tangential direction of the gap trajectory, the energy flow direction does not completely coincide with the tangential direction of the gap trajectory, thereby suppressing the transverse high-order modes in the acoustic wave resonator. In addition, due to the difference in the energy flow directions of the target acoustic wave mode and the parasitic mode, the target acoustic wave mode can have a smaller incident angle of energy flow, while the parasitic mode has a larger incident angle of energy flow, achieving the suppression of out-of-band parasitic modes. Compared with directly using a large tilt angle to suppress high-frequency parasitic modes, it can ensure that the Q value of the target acoustic wave mode does not decrease excessively.

[0164] In the embodiments of the present application, the top electrode 10 further includes a reflection grating 130, and the reflection grating 130 is used to reflect acoustic waves, thereby preventing acoustic waves from leaking into areas other than the interdigital electrodes. The reflection grating 130 includes a reflection grating 130 electrode and a reflection grating 130 bus bar, and the extending direction of the reflection grating 130 electrode has a preset angle with the acoustic wave propagation direction. In some embodiments, the extending direction of the reflection grating 130 electrode can be perpendicular to the acoustic wave propagation direction. As Figure 2 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 arranged on both sides of a preset number of interdigital electrode pairs, that is, on both sides of the first finger electrode 110 and the second finger electrode 120.

[0165] In some alternative embodiments, the acoustic wave resonator further includes a bottom electrode 30. The bottom electrode 30 is arranged on the second surface of the piezoelectric thin film 20, and the second surface is opposite to the first surface. The first surface of the piezoelectric thin film 20 can be the upper surface of the piezoelectric thin film 20, and the first surface can be the lower surface of the piezoelectric thin film 20. Optionally, the bottom electrode 30 can be a block electrode, a planar electrode, an interdigital electrode, etc.

[0166] As an alternative implementation manner, the bottom electrode 30 is a planar electrode. Figure 10 The structural schematic of an acoustic wave resonator provided by the embodiments of the present application Figure 2 is shown in Figure 10 As shown, the acoustic wave resonator includes a bottom electrode 30, a piezoelectric thin film 20, and a top electrode 10 arranged in sequence from bottom to top. Among them, the bottom electrode 30 can be a planar electrode.

[0167] As another alternative implementation manner, the bottom electrode 30 is an interdigital electrode. Figure 11 The structural schematic of an acoustic wave resonator provided by the embodiments of the present application Figure 3 is shown in Figure 11As shown, the acoustic resonator includes a bottom electrode 30, a piezoelectric thin film 20, and a top electrode 10, which are arranged in sequence from bottom to top. The bottom electrode 30 can be an interdigital electrode. Among them, the electrode finger bars of the bottom electrode 30 correspond one by one to the electrode finger bars in the top electrode 10.

[0168] In some other alternative embodiments, the acoustic resonator further includes a support substrate 40, and the piezoelectric thin film 20 is disposed on the support substrate 40. Optionally, the material of the support substrate 40 is one of sapphire, silicon, spinel, silicon carbide, diamond, diamond-like, silicon nitride, boron nitride, boron carbide, quartz, germanium, aluminum nitride, silicon nitride, yttrium aluminum garnet, lithium tantalate, lithium niobate. As an example, the piezoelectric thin film 20 is lithium tantalate or lithium niobate, and the support substrate 40 is silicon, sapphire, quartz or silicon carbide. As another example, Figure 12 The structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 4 , such as Figure 12 As shown, the acoustic resonator includes a support substrate 40, a bottom electrode 30, a piezoelectric thin film 20, and a top electrode 10, which are arranged in sequence from bottom to top. Among them, the bottom electrode 30 can be a planar electrode.

[0169] In some other alternative embodiments, at least one intermediate dielectric layer 50 is further disposed between the piezoelectric thin film 20 and the support substrate 40. Figure 13 The structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 5 , such as Figure 13 As shown, the acoustic resonator includes a support substrate 40, an intermediate dielectric layer 50, a bottom electrode 30, a piezoelectric thin film 20, and a top electrode 10, which are arranged in sequence from bottom to top. Among them, the bottom electrode 30 can be an interdigital electrode. The function of the intermediate dielectric layer 50 can be to accelerate the heat dissipation of the acoustic resonator, or to reduce the power consumption of the acoustic resonator, or to perform temperature compensation on the radio frequency signal, etc. 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, polysilicon, amorphous silicon. As an example, the piezoelectric thin film 20 is lithium tantalate or lithium niobate, the intermediate dielectric layer 50 is silicon oxide, and the support substrate 40 is sapphire, quartz or silicon carbide, etc. As another example, the piezoelectric thin film 20 is lithium tantalate or lithium niobate, the intermediate dielectric layer 50 is silicon oxide and polysilicon, and the support substrate 40 is silicon.

[0170] In the above embodiments, the acoustic resonator may also not include the support substrate 40, that is, the piezoelectric thin film 20 is directly disposed on the intermediate dielectric layer 50. Figure 14 The structural schematic of an acoustic resonator provided by an embodiment of the present application Figure 6 , such as Figure 14As shown, the acoustic resonator includes an intermediate dielectric layer 50, a piezoelectric thin film 20, and a top electrode 10 that are sequentially arranged from bottom to top.

[0171] In some other alternative embodiments, a Bragg reflector layer 60 may further be disposed between the piezoelectric thin film 20 and the support substrate 40. Figure 15 The structural schematic diagram of an acoustic resonator provided by an embodiment of the present application Figure 7 , such as Figure 15 As shown, the acoustic resonator includes a support substrate 40, a Bragg reflector layer 60, a piezoelectric thin film 20, and a top electrode 10 that are sequentially arranged from bottom to top.

[0172] In the embodiment of the present application, a load structure 70 is disposed in the region where the first electrode finger 111 corresponds to the second gap track and the region where the second electrode finger 121 corresponds to the first gap track. Optionally, the load structure 70 may be disposed on the piezoelectric thin film 20 or on the electrode fingers. The load structure 70 is used to reduce the sound velocity in the gap region, so that sound waves can more easily enter the dummy finger electrode region, and in this case, a smaller incident angle of energy inflow is required. 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 alternative implementation manner, Figure 16 The structural schematic diagram of a top electrode provided by an embodiment of the present application Figure 3 , such as Figure 16 As shown, in the acoustic resonator, a load block 71 is disposed in the air gap region, and the load block 71 is disposed in the region where the first electrode finger 111 corresponds to the second gap track and the region where the second electrode finger 121 corresponds to the first gap track. Optionally, the load block 71 may be disposed on the piezoelectric thin film 20, or on the first electrode finger 111 and / or the second electrode finger 121, or may be integrally provided 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, so that sound wave energy can more easily enter the dummy finger electrode region, which is beneficial to the suppression of the transverse mode.

[0174] As another alternative implementation manner, Figure 17 The structural schematic diagram of a top electrode provided by an embodiment of the present application Figure 4 , such as Figure 17As shown in the figure, in this 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 thin film 20, or on the first electrode finger bar 111 and / or the second electrode finger bar 121, or can be integrally provided with the first electrode finger bar 111 and / or the second electrode finger bar 121. The added load bar 72 can reduce the sound velocity in the air gap region, making it easier for the acoustic wave energy to enter the dummy finger electrode region, which is beneficial to the suppression of the transverse mode.

[0175] The acoustic wave resonator described in the embodiment of the present application at least includes a piezoelectric thin film 20 and a top electrode 10. The top electrode 10 includes an interdigital electrode pair, dummy finger electrodes, and an air gap. Among them, the piezoelectric thin film 20 has strong in-plane anisotropy in the electromechanical coupling coefficient, which means that the electromechanical coupling coefficient can be adjusted by changing the in-plane acoustic wave propagation direction. However, in this process, the energy flow angle must not be 0. Therefore, it is stipulated that the average angle between the tangent direction of the gap track and the acoustic wave energy flow direction does not exceed 15°, and the maximum angle is not less than 1°.

[0176] The acoustic wave 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, only the in-plane direction of the electrode needs to be changed without adding an additional dielectric layer, which greatly reduces the processing cost. In addition, as the in-plane acoustic wave propagation direction changes, 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, resulting in a decrease in the Q value of the device. Therefore, a limit is imposed on the angle between the trajectory of the air gap and the energy flow direction. It is stipulated that the angle between the energy flow direction and the tangential direction of the gap track at the i-th pair of interdigital electrodes, that is, the incident angle of the energy flow at the i-th pair of interdigital electrodes, has a maximum value not less than 1°, which can play a role in suppressing the transverse high-order mode. In addition, as the energy flow angle increases, the corresponding optimal angle between the tangential direction of the gap track and the acoustic wave propagation direction increases, which also has an inhibitory effect on the out-of-band parasitic mode, and this inhibitory effect is achieved without sacrificing the Q value of the target acoustic wave mode. The solution proposed in the embodiment of the present application can meet the requirements of different frequency band bandwidths under a single material system. It can also be used for multi-zero design to achieve a flatter passband. At the same time, it can also be used to suppress in-band and out-of-band parasitic modes.

[0177] The 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 multiple acoustic wave resonators in series and / or in parallel. Among the acoustic wave resonators that make up the acoustic wave filter, at least one acoustic wave resonator is the acoustic wave resonator proposed in the above embodiment.

[0179] In some alternative embodiments, the acoustic wave filter may include two or more acoustic wave resonators proposed in the above embodiments, and there may be at least two or more different preset included angles corresponding to the two or more acoustic wave resonators proposed in the above embodiments. That is, the acoustic wave propagation direction angle θ in at least one acoustic wave resonator is different from the acoustic wave propagation direction angle θ in other acoustic wave resonators. In other embodiments, among the two or more acoustic wave resonators proposed in the above embodiments, the acoustic wave propagation direction angles θ of all the acoustic wave resonators are different from each other.

[0180] In some alternative embodiments, among the two or more acoustic wave resonators proposed in the above embodiments, there are series acoustic wave resonators and parallel acoustic wave resonators. Among them, the average angle of the first gap trajectory tangential angle and the second gap trajectory tangential angle in the series acoustic wave resonator is greater than the average angle of the first gap trajectory tangential angle and the second gap trajectory tangential angle in the parallel acoustic wave resonator. In other words, the of the series acoustic wave resonator is greater than that of the parallel acoustic wave resonator This is because a larger angle can suppress the longitudinal high-order mode. And the longitudinal high-order mode on the left side of the resonance frequency of the series acoustic wave resonator may appear in the passband of the acoustic wave filter.

[0181] For the acoustic wave filter described in the embodiments of the present application, in the embodiments 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 resonators that make up the acoustic wave filter. Since the piezoelectric thin film 20 has in-plane anisotropy and the electromechanical coupling coefficients corresponding to different in-plane directions are different, 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 regulation of the electromechanical coupling coefficient, the acoustic wave resonators that make up the acoustic wave filter have different electromechanical coupling coefficients, which is convenient for multi-zero design and makes the acoustic wave filter have a flatter passband.

[0182] The embodiments of the present application also provide an acoustic wave filter module, and the acoustic wave filter module includes the acoustic wave filter as described above.

[0183] In the embodiments of the present application, the acoustic wave filter module can be obtained by combining two or more of the above acoustic wave filters. Among them, two or more acoustic wave filters can be formed on the same piezoelectric thin film 20.

[0184] In the embodiments 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 that makes up the acoustic wave filter module, the maximum relative bandwidth and the minimum relative bandwidth of the acoustic wave filter satisfy the following conditions: (FBWmax -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, and FBW min 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 will be further described below in conjunction with some specific embodiments.

[0186] Embodiment 1:

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

[0188] As Figure 2 or Figure 6 shown, the top electrode 10 includes a first bus bar 113, a second bus bar 123, a plurality of interdigital electrode pairs, a reflection grating 130, and dummy fingers. Among the interdigital electrode pairs, the gap between the end of the electrode finger bar and the dummy finger is an air gap. The gap between the end of the first electrode finger bar 111 and the second dummy finger 122 is the first gap, and the gap between the end of the second electrode finger bar 121 and the first dummy finger 112 is the second gap. The average tangential direction of the first gap trajectory and the acoustic wave energy flow direction is the first average energy incident angle The average tangential direction of the second gap trajectory and the acoustic wave energy flow direction is the second average energy incident angle and The absolute value of does not exceed 15°, so as to ensure that 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 process of adjusting the electromechanical coupling coefficient.

[0189] Figure 19 is a schematic diagram of the change of the acoustic wave energy flow direction and the tangential direction of the gap trajectory of the proposed acoustic wave resonator with the acoustic wave propagation direction angle θ provided by an embodiment of the present application, as Figure 19As shown, regardless of the value of the acoustic wave propagation direction angle θ, the angle between the acoustic energy flow direction and the tangential direction of the gap trajectory remains within 15°.

[0190] Figure 20 A kind provided by the embodiment of the present application Figure 6 The Q value Qp at the anti-resonant frequency corresponding to different tangential angles γ of the corresponding gap trajectory and different acoustic wave propagation direction angles θ is as Figure 20 shown. It can be seen from the figure that when γ - θ is around 7° or γ - θ is around -6°, the Q value of the acoustic resonator remains above 3000, and even exceeds 5000 at the highest. This is because, according to Figure 4 the shown results, when γ - θ is around 7° or γ - θ is around -6°, the incident angle η of the energy flow is small, and a small amount of energy leaks into the false finger electrodes, suppressing the transverse high-order modes near the anti-resonant frequency. At the same time, the incident angle η of the energy is not large enough to cause the target acoustic wave mode to leak into the bus bar, so the Q value is relatively high. When γ - θ is far from 7° or -6°, the Q value may be lower than 1000. This is because the incident angle η of the energy flow is too large or too small at this time.

[0191] Figure 21 A kind of electromechanical coupling coefficient k2 and Qp corresponding to different acoustic wave propagation direction angles θ extracted from another set of experimental results provided by the embodiment of the present application is as Figure 21 shown. It can be seen from the figure that when γ - θ = 6° or γ - θ = 7°, the Q value of the acoustic resonator remains above 3500, and exceeds 5000 at the highest. Especially when the acoustic wave propagation direction angle θ is greater than 10°, the effect of γ - θ = 6° or γ - θ = 7° on improving the Q value is very obvious.

[0192] Figure 22 A admittance curve diagram of an acoustic resonator when the acoustic wave propagation direction angle θ = 20° provided by the embodiment of the present application is as Figure 22 shown. It can be seen from the figure 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 leaky surface acoustic wave in the high-frequency band, and other high-order modes all decrease.

[0193] Figure 23 An impedance phase curve diagram of an acoustic resonator when the acoustic wave propagation direction angle θ = 20° provided by the embodiment of the present application is as Figure 23 shown. It can be seen from the figure that when γ - θ = 7°, compared with γ = 0°. The impedance phase amplitude of the target acoustic wave mode remains basically unchanged, and the impedance phase amplitudes of the Rayleigh mode in the low-frequency band, the longitudinal leaky surface acoustic wave in the high-frequency band, and other high-order modes all decrease. This shows that the scheme proposed in the embodiment of the present application can weaken the parasitic modes while increasing the Q value of the target acoustic wave mode.

[0194] Figure 24 This is the Bode-Q curve graph of an acoustic wave resonator when the acoustic wave propagation direction angle θ = 20°, as Figure 24 shown. It can be seen from the figure that when γ - θ = 7°, compared with γ = 0°, the Q value of the target acoustic wave mode increases significantly.

[0195] Figure 25 This is a Figure 17 corresponding vibration mode diagram of the target acoustic wave mode when the acoustic wave propagation direction angle θ = 20° and γ - θ = 7°, as Figure 25 shown. It can be seen from the figure that although the acoustic wave propagation direction rotates by 20°, resulting in an energy flow angle of about 20°, by adjusting the gap trajectory, the energy flow incident angle η is only about 7°. Therefore, the acoustic wave energy is basically concentrated in the interdigital electrode region, ensuring a high Q value.

[0196] Figure 26 This is the admittance and conductance curve graph of an acoustic wave resonator when the acoustic wave propagation direction angle θ = 0° and γ = 0°, as Figure 26 shown. It can be seen from the figure that there are transverse high-order modes between the resonance frequency and the anti-resonance frequency.

[0197] Figure 27 This is the admittance and conductance curve graph of an acoustic wave resonator when the acoustic wave propagation direction angle θ = 20° and γ - θ = 7°, as Figure 27 shown. It can be seen from the figure that the transverse high-order modes between the resonance frequency and the anti-resonance frequency are basically suppressed, and the energy flow incident angle at this time is about 7°. Therefore, a smaller energy flow incident angle can suppress the transverse high-order modes.

[0198] Figure 28 This is a schematic diagram of the displacement distribution of the transverse high-order modes corresponding to an excessively small energy flow incident angle η, a suitable energy flow incident angle η, and an excessively large energy flow incident angle η, as Figure 28 shown. According to the excitation coefficient formula where Φ is the displacement distribution of the transverse high-order mode and W is the length of the overlapping region of the interdigital electrodes. When the molecular integral is 0, the transverse high-order mode is suppressed, that is, the positive and negative in the shaded part of the figure cancel each other out. When the energy flow incident angle η is too small, the vibration of the acoustic wave is concentrated in the overlapping region of the interdigital electrodes, showing a similar sine distribution, and the molecular integral is not 0. When the energy flow incident angle η is appropriate, the acoustic wave leaks to the dummy finger electrodes but does not leak to the bus bar region. At this time, due to the change in the displacement distribution, the molecular integral becomes 0. When the incident angle η is too large, both the transverse 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 wave resonator.

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

[0200] Figure 29 The structure diagram corresponding to a SAW filter provided by an embodiment of the present application Figure 1 , and Table 1 is the parameter table of the SAW filter. As Figure 29 shown, it can be seen from the figure that different SAW resonators in the SAW filter have different SAW propagation directions and gap tangent directions. As shown in Table 1, in order to reduce the bandwidth, the SAW resonators generally have a relatively large SAW propagation direction angle θ.

[0201] Table 1 Parameter table one of a SAW filter

[0202]

[0203] Figure 30 The admittance curves and Bode-Q curves of each SAW resonator corresponding to the SAW filter shown in Table 1 provided by an embodiment of the present application, as Figure 30 shown, it can be seen from the figure that although the SAW resonators have a relatively large SAW propagation direction angle θ, the Q values of each SAW resonator are all above 3000.

[0204] Figure 31 The S-parameter curves corresponding to the SAW filter shown in Table 1 of an embodiment of the present application, as Figure 31 shown, it can be seen from the figure that although having a relatively large SAW propagation direction angle θ, the insertion loss of the SAW filter is about 1.07 dB, and the relative bandwidth is about 2.55%.

[0205] Figure 32 The structure diagram corresponding to a SAW filter provided by an embodiment of the present application Figure 2 , and Table 2 is the parameter table of the SAW filter. As Figure 32 shown, it can be seen from the figure that different SAW resonators in the SAW filter have different SAW propagation directions and gap tangent directions. The SAW propagation direction angle θ is relatively smaller than that in Table 1, and the target bandwidth is larger.

[0206] Table 2 Parameter table two of a SAW filter

[0207]

[0208] Figure 33 The S21 curves corresponding to the SAW filters shown in Table 1 and Table 2 provided by an embodiment of the present application, as Figure 33As shown, the bandwidths of the two acoustic wave filters are 50 MHz and 68 MHz respectively, the relative bandwidths are 2.55% and 3.47% respectively, and the insertion losses are 1.07 dB and 0.77 dB respectively. The two acoustic wave filters have low insertion losses and different relative bandwidths. The feasibility of implementing acoustic wave filters with different relative bandwidths on the same piezoelectric substrate proposed in the embodiments of the present application is demonstrated.

[0209] Figure 34 FIG. 4 is a schematic structural diagram of a comparative acoustic wave filter, and Table 3 is a parameter table of the acoustic wave filter. As Figure 30 shown, it can be seen from the figure that different acoustic wave resonators in the acoustic wave filter have different acoustic wave propagation directions, and the tangent direction of the gap is the same as the acoustic wave propagation direction.

[0210] Table 3 Parameter Table of a Comparative Acoustic Wave Filter

[0211]

[0212]

[0213] Figure 35 FIG. 5 is the S-parameter curve corresponding to the acoustic wave filter in Table 3. As Figure 30 shown, it can be seen from the figure that due to the excessive incident angle η of the energy flow, the insertion loss of the acoustic wave filter reaches 2.22 dB.

[0214] Figure 36 FIG. 6 is a schematic structural diagram of an acoustic wave filter provided by an embodiment of the present application Figure 3 , and Table 4 is a parameter table of the acoustic wave filter. As Figure 36 shown, it can be seen from the figure that different acoustic wave resonators in the acoustic wave filter have different acoustic wave propagation directions, and the tangent direction of the gap is not parallel to the acoustic wave propagation direction.

[0215] Table 4 Parameter Table of an Acoustic Wave Filter III

[0216]

[0217] Figure 37 FIG. 7 is the S-parameter curve corresponding to the acoustic wave filter in Table 4 provided by an embodiment of the present application. As Figure 37 shown, it can be seen from the figure that due to the incident angle η of the energy flow being limited within a certain range, the insertion loss of the acoustic wave filter is reduced to 1.01 dB.

[0218] Figure 38 FIG. 8 is the S21 curve corresponding to the acoustic wave filters shown in Table 3 and Table 4 provided by an embodiment of the present application. As Figure 38As shown, the acoustic wave propagation directions of the acoustic wave resonators of the two acoustic wave filters are the same respectively. After restricting the incident angle η of the energy flow. The insertion loss of the acoustic wave filter in Table 4 is reduced from 2.22 dB to 1.01 dB compared with that in Table 3. This shows that by changing the air gap tangential direction to control the incident angle η of the energy flow, the loss caused by the excessive energy flow angle during the bandwidth adjustment process can be compensated. In addition, the out-of-band fluctuations caused by the Rayleigh mode and the high-frequency mode near 2.8 GHz are also weakened, which helps to improve the out-of-band rejection level.

[0219] Embodiment 2:

[0220] Figure 39 The structural schematic diagram of an acoustic wave resonator provided by an embodiment of the present application Figure 9 , as Figure 39 shown, the acoustic wave resonator includes a support substrate 40, a first intermediate dielectric layer 51, a second intermediate dielectric layer 52, a piezoelectric thin film 20 and a top electrode 10 from bottom to top. Among them, the material of the support substrate 40 is silicon, the material of the first intermediate dielectric layer 51 is polysilicon, and its thickness is 1 μm. The material of the second intermediate dielectric layer 52 is silicon oxide, and its thickness is 500 nm. The piezoelectric thin film 20 is lithium tantalate with Y42 cut, and its thickness is 600 nm. The top electrode 10 is titanium / aluminum / titanium, and their thicknesses are 2 nm / 120 nm / 3 nm respectively, and the first reference axis is the crystal X axis.

[0221] Figure 40 The Q value Qp at the anti-resonant frequency corresponding to different gap trajectory tangential angles γ and different acoustic wave propagation direction angles θ provided by an embodiment of the present application, as Figure 40 shown, it can be seen from the figure that when γ - θ is around 5° or γ - θ is around -6°, the Q value of the acoustic wave resonator remains above 3000. This is because the incident angle η of the energy flow is moderate at this time. When γ - θ is far from 5° or -6°, the Q value may be lower than 1000. This is because the incident angle η of the energy flow is too large or too small at this time.

[0222] Figure 41 The admittance curve diagram of an acoustic wave resonator when the acoustic wave propagation direction angle θ = 0° and γ = -5°, and when the acoustic wave propagation direction angle θ = 4° and γ = 10° provided by an embodiment of the present application, Figure 42 The Bode-Q curve diagram of an acoustic wave resonator when the acoustic wave propagation direction angle θ = 0° and γ = -5°, and when the acoustic wave propagation direction angle θ = 4° and γ = 10° provided by an embodiment of the present application, as Figure 41 and Figure 42 shown, it can be seen from the figure that the maximum Q value that can be obtained when the acoustic wave propagation direction angle θ ≠ 0° is higher than that when the acoustic wave propagation direction angle θ = 0°. This is because the design dimension is increased, so as to more finely adjust the incident angle η of the energy flow.

[0223] Figure 43 The admittance curve of a SAW resonator when γ is 0°, the acoustic wave propagation direction angle θ = 0° and the acoustic wave propagation direction angle θ = 20° provided by an embodiment of the present application. Figure 44 The Bode-Q curve of a SAW resonator when γ is 0°, the acoustic wave propagation direction angle θ = 0° and the acoustic wave propagation direction angle θ = 20° provided by an embodiment of the present application, as Figure 43 and Figure 44 shown. It can be seen from the figure that when the acoustic wave propagation direction angle θ = 20° compared with the acoustic wave propagation direction angle θ = 0°, due to the increase in the incident angle of energy flow, the Q value drops significantly.

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

[0225] Figure 46 The admittance curve of a SAW resonator when the acoustic wave propagation direction angle θ = 20° provided by an embodiment of the present application, as Figure 46 shown. It can be seen from the figure 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 leaky surface acoustic wave in the high-frequency band, and other higher-order modes all decrease.

[0226] Figure 47 The impedance phase curve of a SAW resonator when the acoustic wave propagation direction angle θ = 20° provided by an embodiment of the present application, as Figure 47 shown. It can be seen from the figure that when γ - θ = 6°, compared with γ = 0°. The impedance phase amplitude of the target acoustic wave mode remains basically unchanged, and the impedance phase amplitudes of the Rayleigh mode in the low-frequency band, the longitudinal leaky surface acoustic wave in the high-frequency band, and other higher-order modes all decrease. It shows that the scheme 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] Figure 48 The Bode-Q curve of a SAW resonator when the acoustic wave propagation direction angle θ = 20° provided by an embodiment of the present application, as Figure 48 shown. It can be seen from the figure that when γ - θ = 6°, compared with γ = 0°. The Q value of the target acoustic wave mode increases significantly.

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

[0229] Table 5 The fourth parameter table of an acoustic wave filter

[0230]

[0231] Figure 49 is the structural schematic diagram corresponding to an acoustic wave filter provided by an embodiment of the present application Figure 5 , Table 6 is the parameter table of this acoustic wave filter. As Figure 49 shown, it can be seen from the figure that different acoustic wave resonators in this acoustic wave filter have different acoustic wave propagation directions, and the tangent direction of the gap is not parallel to the acoustic wave propagation direction.

[0232] Table 6 The fifth parameter table of an acoustic wave filter

[0233]

[0234] Figure 50 is the S-parameter curve corresponding to the acoustic wave filters shown in Table 5 and Table 6 provided by an embodiment of the present application. As Figure 50 shown, the bandwidths of the two acoustic wave filters are 47 MHz and 65 MHz respectively, the relative bandwidths are 2.47% and 3.41% respectively, and the insertion losses are 1.05 dB and 0.9 dB respectively. The two acoustic wave filters have low insertion losses and different relative bandwidths. It proves the feasibility of implementing acoustic wave filters with different relative bandwidths on the same piezoelectric substrate proposed by the embodiment of the present application.

[0235] Embodiment 3:

[0236] Figure 51 is the structural schematic diagram of an acoustic wave resonator provided by an embodiment of the present application Figure 10 , as Figure 51 shown, this acoustic wave resonator includes a support substrate 40, a piezoelectric thin film 20 and a top electrode 10 from bottom to top. Among them, the material of the support substrate 40 is silicon. The piezoelectric thin film 20 is X-cut lithium tantalate, and its thickness is 600 nm. The top electrode 10 is aluminum, and its thickness is 150 nm. The first reference axis is the crystal Y axis.

[0237] Figure 52 is the variation of the electromechanical coupling coefficient k2, the target acoustic wave mode and the energy flow angle τ of the parasitic mode with the acoustic wave propagation direction angle θ of an acoustic wave resonator provided by an embodiment of the present application. As Figure 52As shown, when the acoustic wave propagation direction angle θ = 167°, the electromechanical coupling coefficient of the target acoustic wave mode SH0 mode reaches the maximum. At this time, the difference between the energy flow angle of the Rayleigh mode and the SH0 mode is 1°. When the acoustic wave propagation direction deviates from the direction where k2 takes the 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] Figure 53 The admittance curves of the acoustic wave resonator when the acoustic wave propagation direction angle θ is 157°, γ = 0° and γ = -20° provided by the embodiment of the present application are as follows Figure 53 As shown, when γ = -20° compared with γ = 0°, the admittance ratio of the target acoustic wave mode increases, while the admittance ratio of the Rayleigh mode decreases. This is because at this time, the incident angle of the energy flow of the Rayleigh mode reaches 20°, while the incident angle of the energy flow of the target acoustic wave mode is still within 15°.

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

[0240] The embodiment of the present application aims at the problems that the existing acoustic wave resonator is difficult to adjust the electromechanical coupling coefficient, and the complex process or increased loss accompanied in the process of adjusting the electromechanical coupling coefficient. It is proposed to use a single-crystal piezoelectric thin film with strong in-plane anisotropy to adjust the electromechanical coupling coefficient by changing the in-plane acoustic wave propagation direction of the acoustic wave, and at the same time control the angle between the tangential direction of the gap trajectory and the energy flow direction of the target acoustic wave mode to avoid energy leakage caused by too large energy incident angle. Acoustic wave resonators with different electromechanical coupling coefficients are realized on the same piezoelectric thin film, and then acoustic wave filters with different relative bandwidths are realized. Acoustic wave filters are composed of acoustic wave resonators with different electromechanical coupling coefficients to meet the multi-zero design requirements and obtain a flatter passband. At the same time, the tangential direction of the gap trajectory is not completely parallel to the energy flow direction of the target acoustic wave mode to suppress the transverse high-order mode. In addition, by selecting a suitable in-plane direction, the energy flow direction of the out-of-band parasitic mode can 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 leak into the bus bar area while maintaining a high Q value of the target acoustic wave mode, realizing an improvement in the out-of-band suppression level.

[0241] It should be noted that the above sequence of the embodiments of the present application is only for description and does not represent the superiority or inferiority of the embodiments. And the above specific embodiments of this specification have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require the particular order or sequential order shown to achieve the desired result. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

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

[0243] Those of ordinary skill in the art can understand that all or part of the steps to implement the above embodiments can be completed by hardware, or can be completed by a program instructing relevant hardware. The program can be stored in a computer-readable storage medium. The above-mentioned storage medium can be a read-only memory, a magnetic disk, an optical disk, or the like.

[0244] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall 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, the angle between the average tangent of the second gap trajectory and the second reference axis is the second gap trajectory tangent angle, and the first gap trajectory tangent angle and the second gap trajectory tangent angle meet a preset condition; the angle between the second reference axis and the acoustic wave energy flow direction of the acoustic wave resonator is taken as a reference energy flow angle, and the preset condition is that the absolute value of the difference between the first gap trajectory tangent angle and the second gap trajectory tangent angle and the reference energy flow angle does not exceed 15 degrees.

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 Taking the direction of the acoustic wave energy flow of the acoustic wave resonator as a third reference axis; 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, yttrium aluminum garnet, lithium tantalate, and lithium niobate.

21. The acoustic wave resonator according to claim 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 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 7, 9, 10, 12, 13, 15 to 18, 20 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 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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