Resonator, filter and electronic device

Abstract

Provided are a resonator (300), a filter (200) and an electronic device (100). The resonator (300) comprises a substrate (10), a first electrode (20), a piezoelectric layer (30), and a plurality of second electrodes (40). The resonator (300) further comprises a first bus bar (601) and a second bus bar (602). Of every two adjacent second electrodes (40) among the plurality of second electrodes (40), one is a first interdigital electrode (401), and the other is a second interdigital electrode (402). The orthographic projection of the first electrode (20) on the substrate (10) is a first projection, and the orthographic projection of the plurality of second electrodes (40) on the substrate (10) is a second projection; the boundary of the first projection in a first direction is located within the boundary of the second projection in the first direction, the first direction being the extension direction of a first target interdigital electrode (401) among a plurality of first interdigital electrodes (401). A gap region is formed between the bus bars and fingertip ends of interdigital electrodes; the area of the first electrode (20) is reduced, and there is no need to provide the first electrode (20) at a position corresponding to the gap region, such that the acoustic velocity in the gap region is improved, enabling an increase in the acoustic velocity difference between the gap region and an aperture region in which the plurality of second electrodes (40) are located, achieving the effect of suppressing transverse modes.

Description

Resonators, filters, electronic devices

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on March 29, 2024, with application number 202410389179.8 and invention name “Resonator, filter, electronic device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of resonators, and in particular to a resonator, a filter, an electronic device including a filter or a resonator, and a method for preparing the resonator or the filter. Background Art

[0003] With the development of communication technology, the demand for resonators in electronic devices will increase significantly. For example, BAW resonators such as horizontally-excited bulk acoustic resonators (XBARs), vertically-excited bulk acoustic resonators (YBARs), and film bulk acoustic resonators (FBARs) have attracted widespread attention.

[0004] Among them, YBAR has greater coupling and more effective resonance modes and can be used in a larger passband bandwidth.

[0005] However, in YBAR devices, how to effectively suppress the transverse mode is a key technical issue currently faced. Summary of the Invention

[0006] The present application provides a resonator, a filter having a resonator, and an electronic device including a filter or a resonator. The purpose is to provide a resonator that can suppress transverse modes.

[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0008] In one aspect, the present application provides a resonator. In one embodiment, the resonator may be an acoustic wave resonator, such as a YBAR.

[0009] The resonator includes a substrate, a first electrode stacked on the substrate, a piezoelectric layer and a plurality of second electrodes, the piezoelectric layer having a first side and a second side, the plurality of second electrodes being located on the first side, and the first electrode and the substrate being located on the second side, so that the piezoelectric layer is excited to generate resonance by utilizing the vertical electric field formed between the first electrode and the second electrode, for example, forming a YBAR; the resonator also includes a first bus bar and a second bus bar, the plurality of second electrodes being spaced apart between the first bus bar and the second bus bar; one of each two adjacent second electrodes in the plurality of second electrodes is a first interdigitated electrode, and the other is a second interdigitated electrode; one end of each first interdigitated electrode is connected to the first bus bar, and a gap is formed between the tip of each first interdigitated electrode away from the first bus bar and the second bus bar; one end of each second interdigitated electrode is connected to the second bus bar, and a gap is formed between the tip of each second interdigitated electrode away from the second bus bar and the first bus bar.

[0010] In addition, in the resonator, the orthographic projection of the first electrode on the substrate is the first projection, and the orthographic projections of the multiple second electrodes on the substrate are the second projections; wherein, the boundary of the first projection in the first direction is located within the boundary of the second projection in the first direction, and the first direction is the extension direction of the first target interdigital electrode among the multiple first interdigital electrodes.

[0011] The resonator provided in the present application has a gap between the bus bar and the finger tips of the interdigitated electrodes, forming a gap area. Since the boundary of the first electrode provided in the present application in the first direction is located within the boundary of the multiple second electrodes in the first direction, it can be understood that the area of ​​the first electrode provided in the present application is compressed, and the first electrode may not be set at the position corresponding to the gap area. In this way, the sound velocity of the gap area can be increased, so that the sound velocity difference between the gap area and the aperture area where the multiple second electrodes are located becomes larger, thereby having the effect of suppressing the transverse mode.

[0012] In one achievable method, the first electrode has a first end face and a second end face relative to each other in a first direction, and the surface where the first end face is located is closer to the second bus bar than the surface where the second end face is located; the first end face of the first electrode is flush with the end face of the finger tip of the first target interdigitated electrode.

[0013] It can be understood that: the metal first electrode may not be provided at the position corresponding to the above-mentioned gap area.

[0014] In one feasible manner, the first electrode has a first end face and a second end face relative to each other in a first direction, and the surface on which the first end face is located is closer to the second bus bar than the surface on which the second end face is located; the distance between the first end face of the first electrode and the end face of the finger tip of the first target interdigitated electrode is d, 0<d≤8P, P is the finger spacing of the resonator interdigitated electrodes; wherein, the width dimension of the first target interdigitated electrode is S1, the spacing between the first target interdigitated electrode and one of its adjacent second interdigitated electrodes is S2, the finger spacing P=S1+S2, and the width dimension is the dimension parallel to the surface of the substrate and perpendicular to the first direction.

[0015] In some examples, an end surface of the fingertip of the first target interdigital electrode protrudes from a surface where the first end surface of the first electrode is located.

[0016] In some other examples, the first end surface of the first electrode protrudes from the end surface of the finger tip of the first target interdigital electrode, that is, the first end surface of the first electrode is located in the gap between the finger tip of the first target interdigital electrode and the second bus bar.

[0017] That is to say, the end surface of the first electrode may be slightly retracted or slightly protruded compared to the end surfaces of the finger tips of the interdigital electrodes.

[0018] In one feasible method, the first electrode has a first end face and a second end face relative to each other in a first direction, and the surface on which the first end face is located is closer to the second bus bar than the surface on which the second end face is located; the distance between the surface on which the first end face of the first electrode is located and the end face of the finger tip of the first target interdigitated electrode is d, 0.25≤d≤5P, and P is the finger spacing of the interdigitated electrodes of the resonator.

[0019] In one achievable manner, the resonator further includes an insulating filling layer, the filling layer and the first electrode are located in the same layer, and the filling layer is arranged on the periphery of the first electrode.

[0020] That is, after the first electrode is compressed, the etched portion can be filled with the insulating filling layer.

[0021] In one achievable method, the gap between the finger tip of the first target interdigitated electrode and the second bus bar is a first gap; the piezoelectric layer has a first cavity at a position corresponding to the first gap, the first cavity is recessed from the first side toward the second side, and the first cavity is connected to the first gap.

[0022] In this implementation structure, a cavity is etched in the piezoelectric layer, and the cavity is connected to the gap between the interdigital electrode and the bus bar. In this way, the transverse mode sound wave approaches the free boundary condition at the finger tip of the interdigital electrode. This free boundary condition can make the reflection coefficient of the transverse sound wave at the finger end close to 1 and the reflection phase close to 0, thereby effectively suppressing the transverse resonance mode.

[0023] In one possible implementation, the first cavity passes through from the first side to the second side of the piezoelectric layer.

[0024] That is, the first cavity penetrates the piezoelectric layer in the thickness direction of the piezoelectric layer.

[0025] In one achievable manner, there is a distance between the bottom surface of the first cavity and the second side.

[0026] That is, the first cavity may not penetrate the piezoelectric layer in the thickness direction of the piezoelectric layer.

[0027] In one achievable method, the first cavity has a first side surface and a second side surface opposite to each other in the first direction; the first side surface is flush with the end surface of the finger tip of the first target interdigitated electrode, and the second side surface is flush with the side surface of the second bus bar facing the first bus bar.

[0028] In this way, on the basis of effectively suppressing the lateral mode, it is also easy to implement from the perspective of the preparation process.

[0029] In one achievable manner, the plurality of second interdigital electrodes include a second target interdigital electrode adjacent to the first target interdigital electrode; and the first cavity extends toward the second target interdigital electrode.

[0030] By increasing the area of ​​the first cavity, the transverse mode can be further suppressed.

[0031] In one achievable method, the first cavity has a third side surface and a fourth side surface relative to each other in the second direction, and the first cavity is arranged between two adjacent second interdigitated electrodes, and the two second interdigitated electrodes have a first relative surface and a second relative surface relative to each other, wherein the third side surface is flush with the first relative surface, and the fourth side surface is flush with the second relative surface.

[0032] In one achievable manner, an angle α is formed between an extension direction of the first bus bar and each of the first interdigitated electrodes, where α≠90°.

[0033] In this embodiment, the first bus bar is tilted, and the wave vector k1 of the transverse mode of the main resonant mode is reflected by the bus bar to form k2. The wave vectors k1 and k2 have plane components in the first direction and perpendicular to the first direction, respectively. 1y ,k 1xz and k 2y ,k2xz , k 1y and k 2y Due to the difference in size, the transverse standing waves cannot be effectively superimposed and the transverse mode is suppressed.

[0034] In one achievable manner, an included angle α between an extension direction of the first bus bar and each first interdigitated electrode satisfies 45°≤α≤85°.

[0035] For example, α = 50°, α = 60°, α = 75° or α = 80°

[0036] In one achievable manner, the first bus bar and the second bus bar are arranged in parallel.

[0037] In one implementation, the resonator is used to generate a first-order antisymmetric mode when exciting the piezoelectric layer. The vibration direction of the first-order antisymmetric mode is parallel to a second direction. The second direction is parallel to the surface of the substrate and perpendicular to the first direction.

[0038] When the main resonant mode of the resonator is a first-order antisymmetric mode, the resonator can have a higher electromechanical coupling coefficient. The resonator formed in this way not only has the transverse mode effectively suppressed, but also has a higher electromechanical coupling coefficient.

[0039] In one possible implementation, the piezoelectric layer includes a piezoelectric material; the Euler angle of the piezoelectric material crystal is (90°, 90°, 120°±30°), or the crystal cutting angle and propagation direction of the piezoelectric material are X-cut and (120°±30°)Y-propagation direction, wherein the X direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer, and the (120°±30°)Y direction of the piezoelectric material is in the same direction as the second direction; or the Euler angle of the piezoelectric material crystal is (0°, 90°, 90°±30°), or the crystal cutting angle and propagation direction of the piezoelectric material are Y-cut and (90°±30°)X-propagation direction, wherein the Y direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer, and the (90°±30°)X direction of the piezoelectric material is in the same direction as the second direction.

[0040] Under such Euler angle limitation, combined with the resonator structure of the present application, the resonator can have a larger electromechanical coupling coefficient, for example, the electromechanical coupling coefficient can be greater than 40%.

[0041] And, in this resonator structure, the electromechanical coupling coefficient component k 35 2 >0.4, it can excite the first-order antisymmetric A1 main resonance mode, and the electromechanical coupling coefficient component k 35 2 Other than k, and with a larger value 21 2 、k 222 、k 23 2 、k 24 2 、k 25 2 and k 26 2 The direction of the electric field that excites these electromechanical coupling coefficient components is parallel to the extension direction of the second electrode, and the potential along the extension direction of the second electrode is the same on the second electrode, and the electric field strength is zero, so these electromechanical coupling coefficient components k 22 2 、k 26 2 、k 24 2 、k 32 2 This results in smaller parasitic modes, thereby optimizing the performance of the entire resonator.

[0042] On the other hand, the present application provides a resonator, which includes: a substrate, a first electrode stacked on the substrate, a piezoelectric layer and multiple second electrodes, the piezoelectric layer has a first side and a second side, the multiple second electrodes are located on the first side, and the first electrode and the substrate are located on the second side, so that the piezoelectric layer is excited to produce resonance by utilizing the vertical electric field formed between the first electrode and the second electrode, for example, forming a YBAR; the resonator also includes a first bus bar and a second bus bar, and the multiple second electrodes are arranged at intervals between the first bus bar and the second bus bar; one of each two adjacent second electrodes in the multiple second electrodes is a first interdigitated electrode, and the other is a second interdigitated electrode; one end of each first interdigitated electrode is connected to the first bus bar, and the multiple first interdigitated electrodes include a first target interdigitated electrode, and a first gap is formed between the finger tip of the first target interdigitated electrode away from the first bus bar and the second bus bar; one end of each second interdigitated electrode is connected to the second bus bar, and the multiple second interdigitated electrodes include a second target interdigitated electrode, and a second gap is formed between the finger tip of the second target interdigitated electrode away from the second bus bar and the first bus bar.

[0043] In addition, the piezoelectric layer has a first cavity at a position corresponding to the first gap. The first cavity is recessed from the first side toward the second side, and the first cavity is connected to the first gap.

[0044] In the resonator provided in the present application, a cavity can be etched in the piezoelectric layer, and the cavity is connected to the gap between the interdigitated electrode and the bus bar. In this way, the acoustic waves in the transverse mode approach the free boundary condition at the finger tips of the interdigitated electrodes. This free boundary condition can make the reflection coefficient of the transverse acoustic wave at the finger end close to 1 and the reflection phase close to 0, thereby effectively suppressing the transverse resonance mode.

[0045] In one possible implementation, the first cavity passes through from the first side to the second side of the piezoelectric layer.

[0046] That is, the first cavity penetrates the piezoelectric layer in the thickness direction of the piezoelectric layer.

[0047] In one achievable manner, there is a distance between the bottom surface of the first cavity and the second side.

[0048] That is, the first cavity may not penetrate the piezoelectric layer in the thickness direction of the piezoelectric layer.

[0049] In one achievable manner, the piezoelectric layer has a second cavity at a position corresponding to the second gap, the second cavity is recessed from the first side toward the second side, and the second cavity is connected to the second gap.

[0050] In one achievable method, the first cavity has a first side surface and a second side surface relative to each other in a first direction; the first side surface is flush with the end face of the finger tip of the first target interdigitated electrode, and the second side surface is flush with the side surface of the second bus bar facing the first bus bar; the first direction is parallel to the extension direction of the first target interdigitated electrode.

[0051] In this way, on the basis of effectively suppressing the lateral mode, it is also easy to implement from the perspective of the preparation process.

[0052] In one achievable manner, the first cavity extends toward the second target interdigital electrode.

[0053] By increasing the area of ​​the first cavity, the transverse mode can be further suppressed.

[0054] In one achievable method, the first cavity has a third side surface and a fourth side surface relative to each other in the second direction, and the first cavity is arranged between two adjacent second interdigitated electrodes, and the two second interdigitated electrodes have a first relative surface and a second relative surface relative to each other, wherein the third side surface is flush with the first relative surface, and the fourth side surface is flush with the second relative surface.

[0055] In one achievable manner, an angle α is formed between an extension direction of the first bus bar and each of the first interdigitated electrodes, where α≠90°.

[0056] In this embodiment, the first bus bar is tilted, and the wave vector k1 of the transverse mode of the main resonant mode is reflected by the bus bar to form k2. The wave vectors k1 and k2 have plane components in the first direction and perpendicular to the first direction, respectively. 1y ,k 1xz and k 2y ,k 2xz , k 1y and k 2y Due to the difference in size, the transverse standing waves cannot be effectively superimposed and the transverse mode is suppressed.

[0057] In one achievable manner, an included angle α between an extension direction of the first bus bar and each first interdigitated electrode satisfies 45°≤α≤85°.

[0058] For example, α = 50°, α = 60°, α = 75° or α = 80°

[0059] In one achievable manner, the first bus bar and the second bus bar are arranged in parallel.

[0060] In one implementation, the resonator is used to generate a first-order antisymmetric mode when exciting the piezoelectric layer. The vibration direction of the first-order antisymmetric mode is parallel to a second direction. The second direction is parallel to the surface of the substrate and perpendicular to the first direction.

[0061] When the main resonant mode of the resonator is a first-order antisymmetric mode, the resonator can have a higher electromechanical coupling coefficient. The resonator formed in this way not only has the transverse mode effectively suppressed, but also has a higher electromechanical coupling coefficient.

[0062] In one possible implementation, the piezoelectric layer includes a piezoelectric material; the Euler angle of the piezoelectric material crystal is (90°, 90°, 120°±30°), or the crystal cutting angle and propagation direction of the piezoelectric material are X-cut and (120°±30°)Y-propagation direction, wherein the X direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer, and the (120°±30°)Y direction of the piezoelectric material is in the same direction as the second direction; or the Euler angle of the piezoelectric material crystal is (0°, 90°, 90°±30°), or the crystal cutting angle and propagation direction of the piezoelectric material are Y-cut and (90°±30°)X-propagation direction, wherein the Y direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer, and the (90°±30°)X direction of the piezoelectric material is in the same direction as the second direction.

[0063] Under such Euler angle limitation, combined with the resonator structure of the present application, the resonator can have a larger electromechanical coupling coefficient, for example, the electromechanical coupling coefficient can be greater than 40%.

[0064] On the other hand, the present application also provides a filter, which may include a plurality of electrically connected resonators, and at least one of the plurality of resonators may be the resonator mentioned above.

[0065] Since the filter provided in the present application includes the resonator in the above-mentioned implementation structure, and in the resonator, one method is to suppress the transverse mode and optimize the resonator performance by compressing the area of ​​the first electrode and etching a part of the piezoelectric layer.

[0066] On the other hand, the present application further provides a duplexer, which includes a transmitting channel filter and a receiving channel filter. At least one of the transmitting channel filter and the receiving channel filter can be filtered using the above-mentioned filter.

[0067] On the other hand, the present application also provides a multiplexer, which includes multiple transmit channel filters and multiple receive channel filters, wherein at least one of the multiple transmit channel filters, or at least one of the multiple receive channel filters can adopt the filter involved in the embodiment of the present application.

[0068] On the other hand, the present application also provides an electronic device, which includes an amplifier, and a filter, a duplexer or a multiplexer in the above-mentioned implementation method, and the filter, the duplexer or the multiplexer can be electrically connected to the amplifier.

[0069] The electronic device provided in the embodiment of the present application includes the above-mentioned filter, duplexer or multiplexer. Therefore, the electronic device provided in the embodiment of the present application and the filter, duplexer or multiplexer of the above-mentioned technical solution can solve the same technical problems and achieve the same expected effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] FIG1 is a graph showing the amplitude of the transverse standing wave of the resonator when the order n is 1 to 11;

[0071] FIG2 is a schematic diagram of a portion of the structure of an electronic device;

[0072] FIG3 is a schematic diagram of a partial structure of an electronic device;

[0073] FIG4 is a schematic diagram of a partial structure of a filter in an electronic device;

[0074] FIG5 is a schematic diagram showing a partial structure of a resonator provided in an embodiment of the present application;

[0075] FIG6 is a schematic diagram showing a partial structure of a resonator provided in an embodiment of the present application;

[0076] FIG7 shows a schematic diagram of a partial structure of a resonator provided in an embodiment of the present application;

[0077] FIG8 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0078] FIG9 is a cross-sectional view taken along line AA of FIG8 ;

[0079] FIG10 is a BB cross-sectional view of FIG8;

[0080] FIG11 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0081] FIG12 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0082] FIG13 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0083] FIG14 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0084] FIG15 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0085] FIG16 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0086] FIG17 shows an admittance curve of a resonator in related art;

[0087] FIG18 shows an admittance curve of a resonator provided in an embodiment of the present application;

[0088] FIG19 shows an admittance curve of a resonator provided in an embodiment of the present application;

[0089] FIG20 shows a phase curve diagram of a resonator in related art;

[0090] FIG21 shows a phase curve diagram of a resonator provided in an embodiment of the present application;

[0091] FIG22 shows a phase curve diagram of a resonator provided in an embodiment of the present application;

[0092] FIG23 shows a sound velocity curve of a resonator in related art;

[0093] FIG24 shows a sound velocity curve of a resonator provided in an embodiment of the present application;

[0094] FIG25 shows a sound velocity curve of a resonator provided in an embodiment of the present application;

[0095] FIG26 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0096] FIG27 is a CC cross-sectional view of FIG26;

[0097] FIG28 is a DD cross-sectional view of FIG26;

[0098] FIG29 is a schematic diagram showing a partial structure of a resonator provided in an embodiment of the present application;

[0099] FIG30 is a schematic diagram showing a partial structure of a resonator provided in an embodiment of the present application;

[0100] FIG31 is a cross-sectional view taken along line EE of FIG26;

[0101] FIG32 is a sectional view taken along line FF of FIG26 ;

[0102] FIG33 is a schematic diagram showing a partial structure of a resonator provided in an embodiment of the present application;

[0103] FIG34 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0104] FIG35 is a cross-sectional view taken along line GG of FIG34 ;

[0105] FIG36 is a cross-sectional view taken along line HH of FIG34 ;

[0106] FIG37 shows an admittance curve of a resonator in related art;

[0107] FIG38 shows an admittance curve of a resonator provided in an embodiment of the present application;

[0108] FIG39 shows a phase curve diagram of a resonator in the related art;

[0109] FIG40 shows a phase curve diagram of a resonator provided in an embodiment of the present application;

[0110] FIG41 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0111] FIG42 shows an admittance curve of a resonator provided in an embodiment of the present application;

[0112] FIG43 shows a phase curve diagram of a resonator provided in an embodiment of the present application;

[0113] FIG44 is a schematic diagram of a top view of a resonator provided in an embodiment of the present application;

[0114] FIG45 shows a wave vector diagram of a main resonant mode of a resonator provided in an embodiment of the present application;

[0115] FIG46 shows a wave vector diagram of a transverse mode of a resonator provided in an embodiment of the present application;

[0116] FIG47 shows a wave vector diagram of a transverse mode of a resonator in the related art;

[0117] FIG48 shows a wave vector diagram of a transverse mode of a resonator provided in an embodiment of the present application;

[0118] FIG49 is a schematic diagram showing a top view of a resonator provided in an embodiment of the present application;

[0119] FIG50 shows an admittance curve of a resonator provided in an embodiment of the present application;

[0120] FIG51 shows a phase curve diagram of a resonator provided in an embodiment of the present application;

[0121] FIG52 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0122] FIG53 is the admittance curve and filter bandpass diagram of each resonator in FIG52.

[0123] Reference numerals: 100 - electronic device; 200 - filter; 300 - resonator; 400, 410, 420, 430, 440 - resonators; 500 - antenna; 600 - receiver; 700 - transmitter; 800 - baseband chip; 900 - switch; 60a, 60c, 70a - filters; 60b - low-noise amplifier; 60d - mixer; 60e - buffer; 60f, 70d - voltage-controlled oscillator; 70b - amplifier; 70c - driver; 10 - substrate; 20 - first electrode; 30 - piezoelectric layer; 40 - second electrode; 401 - first interdigital electrode, first target interdigital electrode; 402 - second interdigital electrode, second target interdigital electrode; 601 - first bus bar; 602 - second bus bar; 701 - first gap; 702 - second gap; 80 - filling layer; 901 - first concave cavity; 902 - second concave cavity. DETAILED DESCRIPTION

[0124] Before introducing the structure that can be implemented in the embodiments of the present application, the technical terms involved in the embodiments of the present application are first introduced.

[0125] Piezoelectric effect: This includes the direct piezoelectric effect and the inverse piezoelectric effect. The direct piezoelectric effect refers to the change in the electrical polarization of a piezoelectric material when subjected to a mechanical force, while the inverse piezoelectric effect refers to the deformation of the material when an external electric field is applied. The piezoelectric effect is primarily due to the anisotropy of the piezoelectric material's crystal structure and polarization.

[0126] Main resonant mode, parasitic spurious modes: The parasitic resonant frequency generated by a resonator may be close to the main resonant frequency. These spurious resonances may affect the main resonant mode, thereby affecting the filter's in-band insertion loss and out-of-band rejection performance. The parasitic resonances of a resonator are often referred to as spurious modes. When spurious modes fall near the main resonant mode, for example, near the resonance point or antiresonance point of the main resonant mode, they can affect the filter's in-band insertion loss and out-of-band rejection performance.

[0127] Transverse mode: In a resonator, acoustic waves form transverse standing waves between the busbars, known as transverse modes. In some structures, this refers to the transverse mode of the resonator's primary resonant mode. The resulting transverse mode affects the smoothness of the resonator's admittance curve, which in turn can affect the filter's passband flatness and increase the filter's insertion loss.

[0128] Transverse mode order: In a resonator, acoustic waves form transverse standing waves between the busbars. The wavelength of the transverse standing wave is 1 / n times the busbar spacing, where n is the order of the transverse mode, or the order of the transverse standing wave. Figure 1 shows the amplitude of the transverse standing wave for orders n ranging from 1 to 11.

[0129] Piezoelectric coupling factor Kt 2 : It is a key parameter of the resonator, the electromechanical coupling coefficient Kt 2 It can reflect the conversion efficiency between mechanical energy and electrical energy, the electromechanical coupling coefficient Kt of the resonator 2 Determines the relative frequency width between the resonant frequency and the anti-resonant frequency of the resonator. For example, when the resonator is used in filter design, this relative frequency width directly determines the bandwidth of the filter. It can be considered that the electromechanical coupling coefficient Kt 2 The larger it is, the larger the bandwidth of the filter built by the ladder structure can be, and the better the performance.

[0130] Euler angle of piezoelectric material: The Euler angle characterizes the relative rotation angle relationship between the original piezoelectric crystal structure in the X direction or Y direction, perpendicular to or parallel to the extension direction of the resonator fingers, respectively, in the wafer plane.

[0131] Admittance: In power electronics, admittance is defined as the reciprocal of impedance, symbolized by Y and measured in siemens (S). Like impedance, admittance is a complex number consisting of a real part (conductance G) and an imaginary part (susceptance B): Y = G + jB.

[0132] Admittance curve abs and admittance curve Re: Admittance curve abs(Y) = |Y|, which is the modulus (also known as amplitude) of Y and represents the overall response of the resonator. Re(Y) is the real part of Y, that is, the conductance G, which represents the loss of the resonator.

[0133] The present application provides an electronic device, including but not limited to products such as a radio frequency front end and a filter amplifier module, and may also include terminal devices such as mobile phones, tablet computers (pads), smart wearable products (e.g., smart watches, smart bracelets), virtual reality (VR) devices, augmented reality (AR) devices, drones, or other devices, or may also be base stations, televisions, routers, automobiles, and other devices. The present application does not impose any particular restrictions on the specific form of the electronic device.

[0134] In an electronic device such as the one described above, as shown in FIG2 , the electronic device 100 may include a filter 200 , which may effectively filter out a specific frequency point in the signal or frequencies other than the frequency point to obtain a signal of a specific frequency, or eliminate a signal after a specific frequency, so as to improve the working performance of the electronic device 100 .

[0135] FIG3 shows a partial circuit diagram of an electronic device 100. As shown in FIG3 , the electronic device 100 includes a receiver 600, a transmitter 700, an antenna 500, and a baseband chip 800. The antenna 500 is electrically connected to the receiver 600 and transmitter 700 via a switch 900, respectively. Furthermore, the receiver 600 and transmitter 700 are electrically connected to the baseband chip 800.

[0136] Receiver 600 shown in FIG3 includes filter 60a and filter 60c. A low-noise amplifier 60b is electrically connected between filter 60a and filter 60c. Filter 60c is electrically connected to buffer 60e via mixer 60d. Buffer 60e is electrically connected to voltage-controlled oscillator 60f. FIG3 is merely an exemplary receiver; electronic components may be added or reduced based on this circuit structure.

[0137] Transmitter 700 shown in FIG3 includes a power amplifier (PA) 70b, which is electrically connected to a filter 70a and a driver 70c, respectively. Driver 70c is electrically connected to a voltage-controlled oscillator 70d. Similarly, FIG3 is merely an exemplary transmitter, and electronic components may be added or reduced based on this circuit structure.

[0138] For example, in the transmitter 700 shown in FIG3 , the filter can effectively filter out a specific frequency point or frequencies other than the specific frequency point after the power amplifier amplifies the signal, or the filter can filter out noise signals of the low noise amplifier.

[0139] As shown in FIG. 4 , the filter 200 may include a plurality of resonators 300 connected in series, or a plurality of resonators 300 connected in parallel, or a combination of resonators 300 connected in series and in parallel.

[0140] At least one of the plurality of resonators included in the filter 200 may be the resonator shown in FIG. 5 .

[0141] As shown in Figure 5, a portion of a process structure diagram of a resonator is shown. The resonator includes a substrate 10, a first electrode 20, a piezoelectric layer 30, and a plurality of second electrodes 40. The first electrode 20, the piezoelectric layer 30, and the plurality of second electrodes 40 are disposed on the substrate 10. The plurality of second electrodes 40 are arranged side by side. The piezoelectric layer 30 has a first side and a second side. The plurality of second electrodes 40 are located on the first side, and the first electrode 20 is located on the second side. The first side faces away from the substrate 10, and the second side faces the substrate 10. For example, as shown in Figure 5, the piezoelectric layer 30 is stacked between the first electrode 20 and the plurality of second electrodes 40.

[0142] The example structure in Figure 5 can be used in a bulk acoustic wave resonator (BAW). The main working principle of a BAW resonator is to utilize the piezoelectric effect of piezoelectric materials. Using input and output transducers, the input radio wave signal is converted into mechanical energy. After processing, the mechanical energy is converted back into an electrical signal to filter out unnecessary signals and noise, thereby improving reception quality.

[0143] During operation, the resonator shown in Figure 5 can be disconnected from an electrical signal by applying an alternating voltage of a certain frequency to the second electrode 40. This generates an electric field E between the first electrode 20 and the second electrode 40 along the thickness of the piezoelectric layer 30. The piezoelectric layer 30 utilizes this electric field to produce a piezoelectric effect. The example in Figure 5 utilizes a vertical electric field E to excite the piezoelectric layer 30 to resonate, thereby converting electrical energy into mechanical energy.

[0144] The resonator shown in FIG5 is excited to resonate along the thickness direction of the piezoelectric layer 30. In one embodiment, it can be referred to as a vertically-excited bulk acoustic resonator (YBAR). The thickness direction of the piezoelectric layer 30 here can be understood as the direction of the piezoelectric layer 30 parallel to the stacking direction of the multiple membrane layers (substrate, first electrode, piezoelectric layer).

[0145] In some examples, based on applying voltage to the plurality of second electrodes 40 , the resonator can generate a first-order horizontal shear mode (SH1 mode) in the piezoelectric material of the exciting piezoelectric layer 30 , and the vibration direction of the SH1 mode is parallel to the surface of the substrate and parallel to the extension direction of the second electrode 40 .

[0146] In other examples, as shown in FIG5 , based on applying voltage to the plurality of second electrodes 40, the resonator can generate a first-order anti-symmetric mode (First-order Anti-symmetry mode) A1 mode when exciting the piezoelectric material of the piezoelectric layer 30. The vibration direction of the A1 mode is parallel to the surface of the substrate and perpendicular to the extension direction of the second electrode 40. The black solid line with an arrow in FIG5 illustrates the vibration direction of the piezoelectric layer 30. When the main resonant mode of the resonator is the A1 mode, the resonator has a higher electromechanical coupling coefficient, which can optimize the resonator performance, for example, the electromechanical coupling coefficient K t 2 It can be greater than 15%.

[0147] For example, in some examples, the crystal cutting angle and propagation direction of the piezoelectric material of the piezoelectric layer 30 are X-cut, (120°±30°) Y-propagation direction; or, it can be understood that the Euler angle of the crystal of the piezoelectric material is (90°, 90°, 120°±30°).

[0148] The "X" in the above-mentioned X-cut represents the X direction of the piezoelectric material. The X-cut can be used to indicate that the X direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer 30 (such as the P direction in Figure 6). The propagation direction of the piezoelectric material is parallel to the surface of the piezoelectric layer and perpendicular to the extension direction of the second electrode 40. In one embodiment, the Y direction of the piezoelectric material (120°±30°) is shown in Figure 6.

[0149] For example, in some other examples, the crystal cutting angle and propagation direction of the piezoelectric material of the piezoelectric layer 30 in the embodiment of the present application are Y-cut, (90°±30°) X-propagation direction; or, the Euler angle of the crystal of the piezoelectric material is (0°, 90°, 90°±30°).

[0150] The "Y" in the above-mentioned Y-cut represents the Y direction of the piezoelectric material. The Y-cut can be used to indicate that the Y direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer 30 (such as the P direction in Figure 7). The X direction of the piezoelectric material (90°±30°) is shown in Figure 7.

[0151] The "same direction" positioning mentioned above allows for a certain error and can be close to the same direction. In one embodiment, a difference of 5° (inclusive) between two angles can be regarded as close to the same direction.

[0152] The Euler angles, cutting angles, or propagation direction limitations involved in the embodiments of this application, for example, the piezoelectric material cutting accuracy is less than ±0.5°, such as: X-cut ±0.5°, Y-cut ±0.5°, etc. In Euler angle expression, it is (90°±0.5°, 90°±0.5°, 120°±30°) or (0°±0.5°, 90°±0.5°, 90°±30°).

[0153] For example, the Euler angles may be (89.5°, 90.5°, 150°), or the Euler angles may be (89.5°, 90.5°, 90°), or the Euler angles may be (89.5°, 90.5°, 120°), or the Euler angles may be (89.5°, 90°, 110°), or the Euler angles may be (90°, 90°, 140°).

[0154] For example, the Euler angles may be (0.5°, 89.5°, 90°), or the Euler angles may be (0°, 90.5°, 110°), or the Euler angles may be (0°, 90.5°, 120°), or the Euler angles may be (0.5°, 90.5°, 100°), or the Euler angles may be (0.5°, 90°, 115°).

[0155] When the Euler angle of the piezoelectric material is (90°, 90°, 120°±30°), or the Euler angle is (0°, 90°, 90°±30°), the electromechanical coupling coefficient component k 35 2 With a larger value, for example, k 35 2 >0.4, or, 0.4 < k 35 2 <0.95, or 0.4 < k 35 2 <0.9253. Thus, using k 35 2 The resonator that excites the main resonant mode will also have a larger electromechanical coupling coefficient K t 2 , for example, the electromechanical coupling coefficient K t 2 It can be greater than 40%.

[0156] In addition, in this resonator structure, the electromechanical coupling coefficient component k 35 2 >0.4, it can excite the first-order antisymmetric A1 main resonance mode, and the electromechanical coupling coefficient component k 35 2 Other than k, and with a larger value 21 2、k 22 2 、k 23 2 、k 24 2 、k 25 2 and k 26 2 The direction of the electric field that excites these electromechanical coupling coefficient components is parallel to the extension direction of the second electrode, and the potential along the extension direction of the second electrode is the same on the second electrode, and the electric field strength is zero, so these electromechanical coupling coefficient components k 22 2 、k 26 2 、k 24 2 、k 32 2 This results in smaller parasitic modes, thereby optimizing the performance of the entire resonator.

[0157] The resonator based on the example of this application should not only have a high electromechanical coupling coefficient K t 2 , it is also necessary to suppress the transverse mode, so that the resonator performance can be further optimized.

[0158] This application exemplifies some achievable resonator structures that can suppress transverse modes, as detailed below.

[0159] As shown in Figure 8, which shows a distribution diagram of a plurality of second electrodes, the plurality of second electrodes include a plurality of first interdigital electrodes 401 and a plurality of second interdigital electrodes 402, and any first interdigital electrode 401 and any second interdigital electrode 402 extend along the first direction.

[0160] Along a direction perpendicular to the extension direction of the first interdigitated electrode 401 or the second interdigitated electrode 402, such as along the second direction shown in Figure 8, multiple first interdigitated electrodes 401 and multiple second interdigitated electrodes 402 can be arranged side by side, and multiple first interdigitated electrodes 401 and multiple second interdigitated electrodes 402 are arranged at intervals. For example, a second interdigitated electrode 402 can be set between two adjacent first interdigitated electrodes 401, and a first interdigitated electrode 401 can be set between two adjacent second interdigitated electrodes 402.

[0161] The resonator also includes a first bus bar 601 and a second bus bar 602, and a plurality of first interdigitated electrodes 401 and a plurality of second interdigitated electrodes 402 arranged side by side are located between the first bus bar 601 and the second bus bar 602, one end of each first interdigitated electrode 401 is connected to the first bus bar 601, and one end of each second interdigitated electrode 402 is connected to the second bus bar 602.

[0162] As shown in Figure 8 , the first bus bar 601 and the second bus bar 602 are arranged in parallel, and both the first bus bar 601 and the second bus bar 602 extend in a direction perpendicular to the extension direction of the first interdigital electrodes 401 or the second interdigital electrodes 402. As shown in Figure 8 , any first interdigital electrode 401 and any second interdigital electrode 402 extend in a first direction, and the first bus bar 601 and the second bus bar 602 extend in a second direction. The first direction and the second direction can be perpendicular to each other, or nearly perpendicular.

[0163] In the example of this application, the transverse mode can be suppressed and the resonator performance can be optimized by changing the structure of the first electrode 20 .

[0164] As shown in Figures 9 and 10, Figure 9 is a cross-sectional view taken along line AA in Figure 8, and Figure 10 is a cross-sectional view taken along line BB in Figure 8. As shown in Figures 8 and 9, each first interdigital electrode 401 includes a head end connected to the first bus bar 601 and a fingertip opposite the head end; as shown in Figures 8 and 10, each second interdigital electrode 402 includes a head end connected to the second bus bar 602 and a fingertip opposite the head end.

[0165] As shown in Figures 8 and 9, the head end of each first interdigital electrode 401 is connected to the first bus bar 601, and a first gap 701 is formed between the tip of a first target interdigital electrode in the plurality of first interdigital electrodes 401 and the second bus bar 602. The first target interdigital electrode can be any first interdigital electrode in the plurality of first interdigital electrodes.

[0166] As shown in Figures 8 and 10, the head end of each second interdigital electrode 402 is connected to the second bus bar 602, and a second gap 702 is formed between the finger tip of the second target interdigital electrode in the plurality of second interdigital electrodes 402 and the first bus bar 601. The second target interdigital electrode can be any second interdigital electrode in the plurality of second interdigital electrodes.

[0167] In Figure 8, the solid box Q1 shows the positive projection of the first electrode 20 in Figures 9 and 10 on the substrate 10, which can be called the first projection, and the dotted box Q2 shows the positive projection of multiple second electrodes 40 (including multiple first interdigitated electrodes 401 and multiple second interdigitated electrodes 402) on the substrate 10, which can be called the second projection.

[0168] The orthographic projection of the second electrode 40 on the substrate 10 can be understood as follows: as shown in Figure 8, there is a spacing between two adjacent first interdigitated electrodes 401, and the side M1 surface of the first bus bar 601 that is not connected to the first interdigitated electrode 401 and faces the second bus bar 602 can be used as the connection boundary between the first interdigitated electrode 401 and the first bus bar 601; there is a spacing between two adjacent second interdigitated electrodes 402, and the side M2 ​​surface of the second bus bar 602 that is not connected to the second interdigitated electrode 402 and faces the first bus bar 601 can be used as the connection boundary between the second interdigitated electrode 402 and the second bus bar 602.

[0169] In some examples, as shown in FIG8 , the boundaries of the orthographic projections of the plurality of second electrodes 40 in the dashed box Q2 on the substrate 10 in the first direction can be understood as the boundary surface M1 and the boundary surface M2 .

[0170] As shown in Figures 9 and 10, the first electrode 20 includes a first end face in the first direction and a second end face opposite to the first end face; the boundary of the positive projection of the first electrode 20 of the solid line frame Q1 shown in Figure 8 on the substrate 10 in the first direction can be understood as the first end face and the second end face.

[0171] In this example, the boundary of the first projection Q1 in the first direction is within the boundary of the second projection Q2 in the first direction. Here, the first direction is parallel to the extension direction of the first target interdigital electrode, or parallel to the extension direction of the second target interdigital electrode. Alternatively, it can be understood that the first direction is parallel to the extension direction of any first interdigital electrode, or parallel to the extension direction of any second interdigital electrode.

[0172] The first target interdigitated electrode involved in the example of this application can be understood as any first interdigitated electrode among multiple first interdigitated electrodes; the second target interdigitated electrode involved in the example of this application can be understood as any second interdigitated electrode among multiple second interdigitated electrodes.

[0173] The boundary of the first projection Q1 in the first direction is located within the boundary of the second projection Q2 in the first direction. There are many ways to implement this, and the following examples provide many implementations.

[0174] As shown in Figures 9 and 10, Figures 9 and 10 exemplify an implementation method in which the boundary of the first projection Q1 in the first direction is located within the boundary of the second projection Q2 in the first direction. In Figure 9, the surface where the first end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the first target interdigital electrode 401. In Figure 10, the surface where the second end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the second target interdigital electrode 402. Thus, the orthographic projection of the first electrode 20 on the substrate is the first projection Q1 shown in Figure 8, and both boundaries of the first projection Q1 in the first direction are located within the boundary of the second projection Q2.

[0175] The surface where the first end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the first target interdigital electrode 401. This can be understood as: the surface where the first end surface of the first electrode 20 is located is completely flush with, or substantially flush with, the end surface of the fingertip of the first target interdigital electrode 401. For example, if the distance between the surface where the first end surface of the first electrode 20 is located and the end surface of the fingertip of the first target interdigital electrode 401 is less than or equal to P / 2, it can be understood as the surface where the first end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the first target interdigital electrode 401, where P is the finger pitch.

[0176] The surface where the second end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the second target interdigitated electrode 402, which can be understood as: the surface where the second end surface of the first electrode 20 is located is completely flush with the end surface of the fingertip of the second target interdigitated electrode 402, or basically close to flush. For example, the distance between the surface where the second end surface of the first electrode 20 is located and the end surface of the fingertip of the second target interdigitated electrode 402 is less than or equal to P / 2, which can be understood as the surface where the second end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the second target interdigitated electrode 402, where P is the finger spacing.

[0177] The finger pitch (Pitch) P can be understood as follows: as shown in FIG8 , the width of the first target interdigital electrode 401 is S1, the spacing between the second target interdigital electrodes 402 adjacent to the first target interdigital electrode 401 is S2, and the finger pitch (Pitch) P is the sum of the width S1 and the spacing S2.

[0178] In some examples, the width dimension S1 of different first interdigitated electrodes in the plurality of first interdigitated electrodes 401 has a process tolerance, for example, the process tolerance may be 1% to 2%, and the spacing S2 between two adjacent first interdigitated electrodes 401 and the second interdigitated electrodes 402 also has a process tolerance, which may be 1% to 2%.

[0179] In some feasible structures, the width dimension of the first interdigitated electrode 401 and the width dimension of the second interdigitated electrode 402 are substantially equal, or nearly equal. For example, the process tolerance of the width dimension of the first interdigitated electrode 401 and the width dimension of the second interdigitated electrode 402 can be 1% to 2%.

[0180] In this example, since the area of ​​the first electrode 20 stacked between the substrate 10 and the piezoelectric layer 30 is compressed, as shown in Figures 9 and 10, a filling layer 80 can be provided in the layer where the first electrode 20 is located. The filling layer 80 can be an insulating layer.

[0181] For example, the filling layer 80 may include at least one insulating material such as SiO2, Si3N4, etc.; or include at least one organic material such as photoresist, polyimide, etc.; or may not be filled with any material to form an air layer.

[0182] As shown in Figure 11, Figure 11 exemplifies another implementation in which the boundary of the first projection Q1 in the first direction is located within the boundary of the second projection Q2 in the first direction. Here, the end surface of the fingertip of the first target interdigital electrode 401 protrudes from the surface where the first end surface of the first electrode 20 is located, and the end surface of the fingertip of the second target interdigital electrode 402 protrudes from the surface where the second end surface of the first electrode 20 is located. In this way, the orthographic projection of the first electrode 20 on the substrate is the first projection Q1 shown in Figure 11, and both boundaries of the first projection Q1 in the first direction are located within the boundary of the second projection Q2.

[0183] In some optional implementation structures, when the end surface of the fingertip of the first target interdigital electrode 401 protrudes from the plane where the first end surface of the first electrode 20 is located, as shown in FIG11 , the spacing d between the end surface of the fingertip of the first target interdigital electrode 401 and the plane where the first end surface of the first electrode 20 is located can be: 0 < d ≤ 8P, where P is the finger pitch of the resonator interdigital electrodes. For example, in the example of 0.25 < d ≤ 8P, d = 1P, or d = 2P, or d = 2.5P, or d = 3P, or d = 5P.

[0184] The spacing d between the end surface of the finger tip of the second target interdigital electrode 402 and the plane where the second end surface of the first electrode 20 is located can be: 0<d≤8P, where P is the interdigital spacing of the resonator interdigital electrodes. For example, in the example of 0.25<d≤8P, d=1P, or d=2P, or d=2.5P, or d=3P, or d=5P.

[0185] In the example of Figure 11, the distance between the end face of the fingertip of the first target interdigitated electrode 401 and the surface where the first end face of the first electrode 20 is located may be equal to or unequal to the distance between the end face of the fingertip of the second target interdigitated electrode 402 and the surface where the second end face of the first electrode 20 is located.

[0186] As shown in FIG. 12 and FIG. 13 , FIG. 12 and FIG. 13 exemplarily provide two further implementations of the boundary of the first projection Q1 in the first direction being within the boundary of the second projection Q2 in the first direction.

[0187] In FIG12 , the end surface of the fingertip of the first target interdigital electrode 401 is flush with the surface where the first end surface of the first electrode 20 is located, and the end surface of the fingertip of the second target interdigital electrode 402 protrudes from the surface where the second end surface of the first electrode 20 is located.

[0188] In FIG13 , the end surface of the fingertip of the first target interdigital electrode 401 protrudes from the surface where the first end surface of the first electrode 20 is located, and the end surface of the fingertip of the second target interdigital electrode 402 is flush with the surface where the second end surface of the first electrode 20 is located.

[0189] In the examples of FIG. 12 and FIG. 13 , both boundaries of the first projection Q1 of the first electrode 20 in the first direction are located within the boundary of the second projection Q2 .

[0190] As shown in FIG14 , FIG14 exemplifies another implementation in which the boundary of the first projection Q1 in the first direction is located within the boundary of the second projection Q2 in the first direction. Here, the first end surface of the first electrode 20 is located on a surface that protrudes from the end surface of the fingertip of the first target interdigital electrode 401, and the second end surface of the first electrode 20 is located on a surface that protrudes from the end surface of the fingertip of the second interdigital electrode 402.

[0191] That is, the surface where the first end face of the first electrode 20 is located is located in the first gap 701 between the finger tip of the first target interdigitated electrode 401 and the second bus bar 602, and the surface where the second end face of the first electrode 20 is located is located in the second gap 702 between the finger tip of the second target interdigitated electrode 402 and the first bus bar 601.

[0192] In this way, both boundaries of the first projection Q1 of the first electrode 20 on the substrate in the first direction are located within the boundary of the second projection Q2.

[0193] In some examples, as shown in FIG14 , the distance between the first end surface of the first electrode 20 and the end surface of the finger tip of the first target interdigital electrode 401 is d, and d can be: 0 < d ≤ 8P, where P is the finger pitch of the resonator interdigital electrodes. For example, in the example of 0.25 < d ≤ 8P, d = 1P, or d = 2P, or d = 2.5P, or d = 3P, or d = 5P.

[0194] The distance d between the second end surface of the first electrode 20 and the end surface of the finger tip of the second target interdigital electrode 402 can be: 0 < d ≤ 8P, where P is the finger pitch of the resonator interdigital electrodes. For example, in the example of 0.25 < d ≤ 8P, d = 1P, or d = 2P, or d = 2.5P, or d = 3P, or d = 5P.

[0195] In some resonators, the distance between the surface where the first end surface of the first electrode 20 is located and the end surface of the fingertip of the first target interdigitated electrode 401 may be equal to or unequal to the distance between the surface where the second end surface of the first electrode 20 is located and the end surface of the fingertip of the second target interdigitated electrode 402.

[0196] As shown in Figure 15, Figure 15 exemplifies another implementation in which the boundary of the first projection Q1 in the first direction is located within the boundary of the second projection Q2 in the first direction. Here, the end surface of the fingertip of the first target interdigital electrode 401 protrudes from the surface where the first end surface of the first electrode 20 is located, and the surface where the second end surface of the first electrode 20 is located protrudes from the end surface of the fingertip of the second target interdigital electrode 402. In other words, both boundaries of the first projection Q1 of the first electrode 20 in the first direction are located within the boundary of the second projection Q2.

[0197] As shown in FIG16 , FIG16 exemplifies another implementation in which the boundary of the first projection Q1 in the first direction is located within the boundary of the second projection Q2 in the first direction. Here, the end surface of the fingertip of the first target interdigital electrode 401 is flush with the surface where the first end surface of the first electrode 20 is located, and the surface where the second end surface of the first electrode 20 is located protrudes from the end surface of the fingertip of the second target interdigital electrode 402.

[0198] That is, both boundaries of the first projection Q1 of the first electrode 20 in the first direction are located within the boundary of the second projection Q2 .

[0199] Figure 17 shows the admittance curve of a resonator using some related technologies, and Figures 18 and 19 show the admittance curves of a resonator using an example of the present application. In the resonator structure of Figure 17 , the first projection Q1 of the first electrode 20 on the substrate and the second projection Q2 of the plurality of second electrodes 40 on the substrate overlap in the first direction, meaning that the dimension of the first electrode 20 in the first direction is not compressed as in the present application.

[0200] In the resonator structure of Figure 18, the surface where the first end face of the first electrode 20 is located is flush with the end face of the fingertip of the first target interdigitated electrode 401, and the surface where the second end face of the first electrode 20 is located is flush with the end face of the fingertip of the second target interdigitated electrode 402.

[0201] 19 , the end surface of the fingertip of the first target interdigital electrode 401 protrudes from the surface where the first end surface of the first electrode 20 is located, and the end surface of the fingertip of the second target interdigital electrode 402 protrudes from the surface where the second end surface of the first electrode 20 is located.

[0202] Figures 17 to 19 are all simulation curves obtained using the parameters shown in Table 1.

[0203] Table 1

[0204] The thickness of the piezoelectric layer and the thickness of the first electrode in Table 1 above are the height dimensions of the piezoelectric layer 30 and the height dimensions of the first electrode 20 along the stacking direction of the multiple film layer structures.

[0205] The duty ratio in Table 1 is the ratio of the width of the first target interdigital electrode 401 to the interdigital spacing, or the ratio of the width of the second target interdigital electrode 402 to the interdigital spacing. In some examples, the width of the first target interdigital electrode 401 is equal to the width of the second target interdigital electrode 402.

[0206] The electromechanical coupling coefficient K in Table 1 above t 2 It can characterize the electromechanical coupling performance of the resonator, the electromechanical coupling coefficient K t 2 The larger it is, the better the electromechanical coupling performance is.

[0207] Next, the transverse mode suppression of the resonator structure involved in the present application and the resonator structure in the related art will be compared with the admittance curves of FIG. 17 and FIG. 19 .

[0208] The admittance curves shown in FIG17 and FIG19 include a transverse mode curve and a real part (Re) curve of the admittance curve.

[0209] Comparing the transverse mode curves in Figure 17 and Figure 18, it can be seen that the transverse mode curves of the resonator in the related art clearly produce n = 1, n = 3, n = 5, n = 7, n = 9, and n = 11 transverse modes. These transverse modes form peaks in the resonator's admittance curve, affecting the vibration of the main resonant mode and the fitting of the related admittance curve. However, as shown in Figures 18 and 19, the responses of the n = 1, n = 3, n = 5, n = 7, n = 9, and n = 11 transverse modes are significantly weakened, and the transverse modes are relatively flat in the resonator's admittance curve.

[0210] Figure 20 is a phase curve of a resonator using some related technologies, and Figures 21 and 22 are phase curves of a resonator using an example of the present application. In the phase curves shown in Figures 20 and 22, the horizontal axis represents the resonant frequency and the vertical axis represents the phase.

[0211] In the resonator structure of Figure 20, the boundaries of the first projection Q1 of the first electrode 20 on the substrate and the second projection Q2 of the multiple second electrodes 40 on the substrate in the first direction overlap, that is, the size of the first electrode 20 in the first direction is not compressed as in this application.

[0212] In the resonator structure of Figure 21, the surface where the first end face of the first electrode 20 is located is flush with the end face of the fingertip of the first target interdigitated electrode 401, and the surface where the second end face of the first electrode 20 is located is flush with the end face of the fingertip of the second target interdigitated electrode 402.

[0213] 22 , the end surface of the fingertip of the first target interdigital electrode 401 protrudes from the surface where the first end surface of the first electrode 20 is located, and the end surface of the fingertip of the second target interdigital electrode 402 protrudes from the surface where the second end surface of the first electrode 20 is located.

[0214] FIG. 20 to FIG. 22 are simulation curves obtained by using the structure shown in Table 1 above.

[0215] In the phase curve shown in Figure 20, the transverse mode of the resonator causes its phase to vary greatly between 50° and 90°, while in the present application shown in Figures 21 and 22, the transverse mode of the resonator causes its phase to vary between 70° and 90°, and the influence of the transverse mode on the main resonant mode of the resonator is significantly weakened.

[0216] From the above comparison, we know that the resonator of the present application example has a higher electromechanical coupling coefficient K t 2 On this basis, the transverse mode can be effectively suppressed and the performance of the resonator can be optimized.

[0217] In the above example, the transverse mode is suppressed by reducing the size of the first electrode 20 .

[0218] In some examples, the principle of suppressing the transverse mode by reducing the size of the first electrode 20 may be understood as follows:

[0219] In the resonator, the elastic acoustic wave formed by the main resonant mode vibrates and propagates inside the resonator. Due to the different structures of the resonator in the transverse aperture direction (such as the first direction of the example in the present application), the propagation speed of the elastic acoustic wave in different transverse aperture directions is different. For example, the area with metal coverage will have a relatively lower sound speed than the area without metal coverage; the resonant part of the middle aperture area has the lowest sound speed due to the coupling of the fingers and the piezoelectric layer. The greater the difference in sound speed between different areas, the less likely it is to form a transverse standing wave, and the more the transverse mode tends to be suppressed.

[0220] Figures 23 to 25 respectively show the sound velocity distribution of three different resonator structures in the transverse aperture direction. In this example, the region in the transverse aperture direction includes two busbar regions, two gap regions, and the aperture region in the middle.

[0221] In the resonator shown in FIG. 23( a ), the boundaries of the first projection Q1 of the first electrode 20 on the substrate and the second projections Q2 of the plurality of second electrodes 40 on the substrate in the first direction coincide with each other.

[0222] In the resonator shown in (a) of Figure 24, the surface where the first end face of the first electrode 20 is located is flush with the end face of the fingertip of the first target interdigitated electrode 401, and the surface where the second end face of the first electrode 20 is located is flush with the end face of the fingertip of the second target interdigitated electrode 402.

[0223] In the resonator shown in (a) of Figure 25, the end face of the finger tip of the first target interdigitated electrode 401 protrudes from the surface where the first end face of the first electrode 20 is located, and the end face of the finger tip of the second target interdigitated electrode 402 protrudes from the surface where the second end face of the first electrode 20 is located.

[0224] Comparing the sound velocity distribution diagrams shown in (b) of Figure 23 and (b) of Figure 24, in Figure 24, since there is no first electrode in the two gap regions, the sound velocity in the gap region is increased, thereby increasing the sound velocity difference between the gap region and the aperture region, thereby achieving a better effect of suppressing the transverse mode.

[0225] Comparing the acoustic velocity distributions shown in Figure 23(b) and Figure 25(b), Figure 25 shows that the absence of the first electrode in the two gap regions increases the acoustic velocity in these gap regions, thereby increasing the acoustic velocity difference between the gap region and the aperture region, thereby achieving better suppression of transverse modes. Furthermore, Figure 25(b) modifies the acoustic velocity at the two finger tip regions, and simulation results show that transverse modes are further suppressed.

[0226] In the above example, the size of the first electrode 20 is compressed to reduce the metal coverage area of ​​the resonator, thereby weakening the transverse mode.

[0227] In some feasible process steps, when the first electrode 20 is manufactured, the size of the first electrode 20 can be reduced through an etching process, and then the bus bar and the interdigitated electrode are manufactured so that the boundary of the first projection Q1 of the first electrode 20 in the first direction is located within the boundary of the second projection Q2 of the second electrode 40 in the first direction.

[0228] The following examples also provide some resonator structures that can suppress transverse modes.

[0229] As shown in Figures 26, 27, and 28, Figure 27 is a CC cross-sectional view of Figure 26, and Figure 28 is a DD cross-sectional view of Figure 26. As shown in Figure 27, a first gap 701 is defined between the fingertips of the first target interdigital electrodes 401 and the second bus bar 602, and a first cavity 901 is defined at a position of the piezoelectric layer 30 corresponding to the first gap 701. The first cavity 901 is recessed from the first side of the piezoelectric layer 30 toward the second side. As shown in Figure 28, a second gap 702 is defined between the fingertips of the second target interdigital electrodes 402 and the first bus bar 601, and a second cavity 902 is defined at a position of the piezoelectric layer 30 corresponding to the second gap 702. The second cavity 902 is recessed from the first side of the piezoelectric layer 30 toward the second side.

[0230] In some examples, as shown in Figures 27 and 28 , the first cavity 901 may pass through from the first side to the second side of the piezoelectric layer 30, and the second cavity 902 may pass through from the first side to the second side of the piezoelectric layer 30. Alternatively, it can be understood that the first cavity 901 passes through the piezoelectric layer 30 along the thickness direction of the piezoelectric layer 30, and the second cavity 902 passes through the piezoelectric layer 30 along the thickness direction of the piezoelectric layer 30.

[0231] In some other examples, the first cavity 901 may not penetrate the piezoelectric layer 30 , and the second cavity 902 may not penetrate the piezoelectric layer 30 , that is, there is a distance between the bottom surface of the cavity and the second side of the piezoelectric layer 30 .

[0232] In other examples, as shown in Figures 27 and 28 , in the first direction, the width of the first cavity 901 is equal to the width of the first gap 701, and the width of the second cavity 902 is equal to the width of the second gap 702. This can be understood as follows: the first cavity 901 has a first side surface and a second side surface that are opposite each other in the first direction; the first side surface is flush with the end surface of the fingertip of the first target interdigital electrode 401, and the second side surface is flush with the side of the second busbar facing the first busbar. In this example, "flush" can be understood as completely flush, or the process tolerance can be less than or equal to 3P, where P is the finger pitch.

[0233] In some examples, as shown in FIG. 29 and FIG. 30 , in the first direction, the width of the first cavity 901 is smaller than the width of the first gap 701 , and the width of the second cavity 902 is smaller than the width of the second gap 702 .

[0234] For example, in the example of Figure 29, the two side walls of the first cavity 901 in the first direction both protrude from the two side walls of the first gap 701. In the example of Figure 30, one of the two side walls of the second cavity 902 in the first direction is flush with the side wall of the second gap 702, and the other side wall protrudes from the side wall of the second gap 702.

[0235] As shown in Figures 31 and 32, Figure 31 is a cross-sectional view taken along line EE of Figure 26, and Figure 32 is a cross-sectional view taken along line FF of Figure 26. As shown in Figure 31, first cavity 901 extends toward second target interdigital electrode 402, which is adjacent to first target interdigital electrode 401. As shown in Figure 32, second cavity 902 extends toward first target interdigital electrode 401, which is adjacent to second target interdigital electrode 402.

[0236] In some examples, as shown in Figures 31 and 32, both side walls of the first cavity 901 in the second direction are flush with the side walls of the second target interdigitated electrode 402, and both side walls of the second cavity 902 in the second direction are flush with the side walls of the first target interdigitated electrode 401.

[0237] In some other examples, as shown in FIG. 33 , both sidewalls of the first cavity 901 in the second direction protrude beyond the sidewalls of the second target interdigital electrode 402 .

[0238] In this example, there is no special limitation on the width of the first cavity 901 in the first direction and the length of the second direction. There is no special limitation on the width of the second cavity 902 in the first direction and the length of the second direction.

[0239] The above example suppresses the transverse mode by etching a cavity in the piezoelectric layer. The principle of suppressing the transverse mode can be understood as follows:

[0240] For a resonator without a cavity etched in the piezoelectric layer 30, the transverse mode sound waves approach fixed boundary conditions at the finger tips. For a resonator with an etched cavity, the transverse mode sound waves approach free boundary conditions at the finger tips. This free boundary condition can make the reflection coefficient of the transverse sound wave at the finger tips close to 1, and the reflection phase close to 0, thereby effectively suppressing the transverse resonance mode. In addition, cavities of different shapes and areas can cause the transverse wave to scatter in different directions, thereby suppressing the transverse resonance mode to a certain extent. The advantage of etching a cavity is that it can limit the leakage of energy in the first direction, thereby maintaining a high quality factor Q within a wide bandwidth.

[0241] In some achievable structures of the present application, as shown in Figures 34, 35, and 36, Figure 35 is a GG cross-sectional view of Figure 34, and Figure 36 is an HH cross-sectional view of Figure 34. As shown in Figures 35 and 36, the dimension of the first electrode 20 in the first direction can be compressed so that the surface where the first end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the first target interdigital electrode 401, the surface where the second end surface of the first electrode 20 is located is flush with the end surface of the fingertip of the second target interdigital electrode 402, and a first cavity 901 is defined at a position of the piezoelectric layer 30 corresponding to the first gap 701, and a second cavity 902 is defined at a position of the piezoelectric layer 30 corresponding to the second gap 702.

[0242] As shown in FIG37 and FIG38 , FIG37 shows the admittance curve of the resonator in the related art, and FIG38 shows the admittance curve of the resonator shown in FIG34 .

[0243] In the admittance curve shown in Figure 37, it can be seen that the transverse mode curve of the resonator in the related art obviously produces n=1, n=3, n=5, n=7, n=9 and n=11 transverse modes. These transverse modes form peaks in the resonator admittance curve, affecting the vibration of the main resonant mode and the fitting of related admittance curves. However, as shown in Figure 38, the n=1, n=3, n=5, n=7, n=9 and n=11 transverse modes, these order transverse mode responses are significantly weakened, and the transverse modes are relatively flat in the resonator admittance curve.

[0244] As shown in FIG39 and FIG40 , FIG39 shows a phase curve of a resonator in related art, and FIG40 shows a phase curve using the resonator shown in FIG34 above.

[0245] In the phase curve shown in Figure 39, the transverse mode of the resonator causes its phase to vary greatly between 50° and 90°, while in the present application shown in Figure 40, the transverse mode of the resonator causes its phase to vary between 70° and 90°, and the influence of the transverse mode on the main resonant mode of the resonator is significantly weakened.

[0246] FIG41 is a diagram of another resonator structure capable of suppressing transverse modes according to an embodiment of the present application. The first electrode 20 can be compressed in the first direction so that the first end surface of the first electrode 20 is flush with the end surface of the fingertip of the first target interdigital electrode 401, the second end surface of the first electrode 20 is flush with the end surface of the fingertip of the second target interdigital electrode 402, and the first cavity 901 extends toward the second target interdigital electrode 402 adjacent to the first target interdigital electrode 401, while the second cavity 902 extends toward the first target interdigital electrode 401 adjacent to the second target interdigital electrode 402.

[0247] FIG42 shows an admittance curve using the resonator shown in FIG41 , and FIG43 shows a transverse mode phase curve using the resonator shown in FIG41 .

[0248] As shown in Figure 42, the transverse mode response is significantly weakened, and the transverse mode is relatively flat in the resonator's admittance curve. As shown in Figure 43, the resonator's transverse mode causes its phase to fluctuate between 70° and 90°, and its influence on the resonator's main resonant mode is significantly weakened.

[0249] In some of the above examples, a cavity is opened in the piezoelectric layer so that the transverse mode acoustic wave approaches the free boundary condition at the tip of the finger, thereby suppressing the transverse mode.

[0250] In some feasible process steps, after the piezoelectric layer is manufactured, a cavity can be opened in the piezoelectric layer through an etching process to reduce the area of ​​the piezoelectric layer.

[0251] Some resonator structures that can suppress transverse modes are also given below.

[0252] For example, as shown in FIG44 , the first bus bar 601 can be arranged at an angle, and the second bus bar 602 can be arranged at an angle. For example, each first interdigitated electrode 401 extends along the first direction of FIG44 , and the angle α1 between the extension direction of the first bus bar 601 and the first direction is not equal to 90°, and the angle α2 between the extension direction of the second bus bar 602 and the first direction is not equal to 90°.

[0253] In some configurations, the first bus bar 601 can be arranged in parallel with the second bus bar 602 .

[0254] In some examples, an included angle α1 between the extension direction of the first bus bar and each first interdigital electrode satisfies 45°≤α1≤85°, for example, α1=60°, α1=70°, or α1=80°.

[0255] An included angle α2 between the extension direction of the second bus bar and each second interdigital electrode satisfies 95°<α2≤135°. For example, α2=120°, α2=110°, or α2=100°.

[0256] In some optional implementation structures, as shown in Figure 44, the end face of the fingertip of the first target forked finger electrode 401 is perpendicular to the extension direction of the first target forked finger electrode 401, that is, the end face of the fingertip of the first target forked finger electrode 401 is parallel to the second direction; the end face of the fingertip of the second target forked finger electrode 402 is perpendicular to the extension direction of the second target forked finger electrode 402, that is, the end face of the fingertip of the second target forked finger electrode 402 is parallel to the second direction.

[0257] The above example suppresses the transverse mode by changing the busbar arrangement to an inclined state relative to the second direction. The principle of suppressing the transverse mode can be understood as follows:

[0258] Taking the main resonance mode A1 mode as an example, as shown in Figure 45, the wave vector of the main resonance mode A1 is the wave vector k in the second direction x and vertical wave vector k z The total wave vector is k xz As shown in Figure 46, the wave vector generated by the transverse mode is along the first direction k y Therefore, the wave vector formed by the transverse mode of the main resonant mode is the main resonant mode wave vector k xz and k y The total wave vector is k.

[0259] As shown in Figure 47, when the extension direction of the two busbars is perpendicular to the interdigital electrodes, the wave vector k1 of the transverse mode of the main resonant mode is reflected by the busbar to form k2. The wave vectors k1 and k2 in the first direction and the plane components perpendicular to the first direction are k 1y ,k 1xz and k 2y ,k 2xz You can see k 1y and k 2y The sizes are the same, the transverse standing waves are superimposed, and the transverse mode is stronger.

[0260] For the resonator proposed in the embodiment of the present application, as shown in FIG48 , when the interdigitated electrodes are tilted, the wave vector k1 of the transverse mode of the main resonant mode is reflected by the bus bar to form k2. The wave vectors k1 and k2 have the plane components in the first direction and perpendicular to the first direction, respectively. 1y ,k 1xz and k 2y ,k 2xz You can see k 1y and k 2y Due to the difference in size, the transverse standing waves cannot be effectively superimposed and the transverse mode is suppressed.

[0261] 49 is a structural diagram of another resonator provided in the present application. In this example, the first bus bar 601 and the second bus bar 602 are both arranged at an angle, and the first end surface of the first electrode 20 is arranged at an angle, and the second end surface of the first electrode 20 is arranged at an angle.

[0262] In some examples, the first end surface of the first electrode 20 is parallel to the extension direction of the first bus bar 601 , and the second end surface of the first electrode 20 is parallel to the extension direction of the second bus bar 602 .

[0263] FIG50 shows an admittance curve using the resonator shown in FIG49 , and FIG51 shows a phase curve using the resonator shown in FIG49 .

[0264] As shown in FIG50 , the transverse mode response is significantly weakened, and the transverse mode is relatively flat in the resonator admittance curve.

[0265] As shown in FIG51 , the transverse mode of the resonator causes its phase to vary between 70° and 90°, and the influence of the transverse mode on the main resonant mode of the resonator is significantly weakened.

[0266] Resonators such as those mentioned above can be used as sensors, such as temperature, humidity, and pressure sensors. Alternatively, they can be used as delay line devices for various high-frequency signal processing applications, such as those in the 100 MHz to 30 GHz range.

[0267] Furthermore, the resonators mentioned above can be electrically connected in a ladder structure as shown in FIG52 to implement a filter for radio frequency communication. In the filter, resonators can be connected in series or in parallel, and the resonant frequency of the parallel resonators can be lower than the resonant frequency of the series resonators.

[0268] In the example of FIG52 , resonators 400, 410, 420, 430, and 440 are included. Resonators 400, 410, and 420 are series resonators, while resonators 430 and 440 are parallel resonators. At least one of resonators 400 to 440 may be the resonator described in the above embodiments.

[0269] In some examples, as shown in FIG53 , FIG53 illustrates the relationship between the admittance curves of the respective resonators of the ladder filter and the transmission loss curve of the filter in FIG52 . Referring to FIG53 , the resonance points of the series resonators (e.g., resonators 400, 410, and 420) and the anti-resonance points of the parallel resonators (e.g., resonators 430 and 440) are located within the passband frequency band, forming the passband of the filter. The anti-resonance points of the series resonators (e.g., resonators 400, 410, and 420) are located on the high-frequency side outside the passband, and the resonance points of the parallel resonators (e.g., resonators 430 and 440) are located on the low-frequency side outside the passband. As a result, the filter exhibits high roll-off and high out-of-band suppression.

[0270] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0271] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A resonator, characterized in that include: substrate; A first electrode, a piezoelectric layer, and a plurality of second electrodes stacked on the substrate, the piezoelectric layer having a first side and a second side, the plurality of second electrodes being located on the first side, and the first electrode and the substrate being located on the second side; a first bus bar and a second bus bar; The plurality of second electrodes are arranged between the first bus bar and the second bus bar at intervals; Among every two adjacent second electrodes in the plurality of second electrodes, one is a first interdigital electrode and the other is a second interdigital electrode; One end of each of the first interdigital electrodes is connected to the first bus bar, and a gap is formed between a tip of each of the first interdigital electrodes away from the first bus bar and the second bus bar; One end of each of the second interdigital electrodes is connected to the second bus bar, and a gap is formed between a tip of each of the second interdigital electrodes away from the second bus bar and the first bus bar; The orthographic projection of the first electrode on the substrate is a first projection, and the orthographic projections of the plurality of second electrodes on the substrate are second projections. The boundary of the first projection in the first direction is located within the boundary of the second projection in the first direction, and the first direction is an extension direction of a first target interdigital electrode among the plurality of first interdigital electrodes.

2. The resonator according to claim 1, characterized in that The first electrode has a first end surface and a second end surface opposite to each other in the first direction, and the first end surface is located closer to the second bus bar than the second end surface. The first end surface of the first electrode is flush with an end surface of a fingertip of the first target interdigital electrode.

3. The resonator according to claim 1, characterized in that The first electrode has a first end surface and a second end surface opposite to each other in the first direction, and the first end surface is located closer to the second bus bar than the second end surface. The distance between the first end surface of the first electrode and the end surface of the finger tip of the first target interdigital electrode is d, 0<d≤8P, P is the finger pitch of the interdigital electrodes of the resonator; The width dimension of the first target interdigital electrode is S1, the spacing between the first target interdigital electrode and one of its adjacent second interdigital electrodes is S2, the finger spacing P = S1 + S2, and the width dimension is a dimension parallel to the surface of the substrate and perpendicular to the first direction.

4. The resonator according to claim 3, characterized in that An end surface of the finger tip of the first target interdigital electrode protrudes from a surface where the first end surface of the first electrode is located.

5. The resonator according to claim 3, characterized in that The first end surface of the first electrode is located in a gap between the finger tips of the first target interdigital electrode and the second bus bar.

6. The resonator according to any one of claims 3 to 5, characterized in that A distance d between a surface where the first end surface of the first electrode is located and an end surface of a fingertip of the first target interdigital electrode satisfies 0.25≤d≤5P.

7. The resonator according to any one of claims 1 to 6, characterized in that The gap between the finger tip of the first target interdigitated electrode and the second bus bar is a first gap; The piezoelectric layer has a first cavity at a position corresponding to the first gap. The first cavity is recessed from the first side toward the second side, and the first cavity is connected to the first gap.

8. The resonator according to claim 7, characterized in that The first cavity passes through from the first side to the second side.

9. The resonator according to claim 7 or 8, characterized in that The first cavity has a first side surface and a second side surface opposite to each other in the first direction; The first side surface is flush with an end surface of a fingertip of the first target interdigital electrode, and the second side surface is flush with a side surface of the second bus bar facing the first bus bar.

10. The resonator according to any one of claims 7 to 9, characterized in that The plurality of second interdigital electrodes include a second target interdigital electrode adjacent to the first target interdigital electrode; The first cavity extends toward the second target interdigital electrode.

11. The resonator according to any one of claims 1 to 10, characterized in that An angle α is formed between an extending direction of the first bus bar and each of the first interdigitated electrodes, where α≠90°.

12. The resonator according to claim 11, characterized in that An included angle α between an extending direction of the first bus bar and each of the first interdigital electrodes satisfies 45°≤α≤85°.

13. The resonator according to claim 11 or 12, characterized in that The first bus bar and the second bus bar are arranged in parallel.

14. The resonator according to any one of claims 1 to 13, characterized in that The resonator is used to generate a first-order antisymmetric mode when exciting the piezoelectric layer. The vibration direction of the first-order antisymmetric mode is parallel to a second direction. The second direction is parallel to the surface of the substrate and perpendicular to the first direction.

15. The resonator according to claim 14, characterized in that The piezoelectric layer includes a piezoelectric material; The Euler angles of the piezoelectric material crystal are (90°, 90°, 120°±30°), or the crystal cutting angle and propagation direction of the piezoelectric material are X-cut and (120°±30°)Y-propagation direction, wherein the X direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer, and the Y direction of the piezoelectric material (120°±30°) is in the same direction as the second direction; or, The Euler angle of the crystal of the piezoelectric material is (0°, 90°, 90°±30°), or the crystal cutting angle and propagation direction of the piezoelectric material are Y-cut and (90°±30°)X propagation direction, wherein the Y direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer, and the (90°±30°)X direction of the piezoelectric material is in the same direction as the second direction.

16. A resonator, characterized in that include: substrate; A first electrode, a piezoelectric layer, and a plurality of second electrodes stacked on the substrate, the piezoelectric layer having a first side and a second side, the plurality of second electrodes being located on the first side, and the first electrode and the substrate being located on the second side; a first bus bar and a second bus bar; The plurality of second electrodes are arranged between the first bus bar and the second bus bar at intervals; Among every two adjacent second electrodes in the plurality of second electrodes, one is a first interdigital electrode and the other is a second interdigital electrode; One end of each of the first interdigital electrodes is connected to the first bus bar, the plurality of first interdigital electrodes include a first target interdigital electrode, and a first gap is formed between a tip of the first target interdigital electrode away from the first bus bar and the second bus bar; One end of each of the second interdigital electrodes is connected to the second bus bar, the plurality of second interdigital electrodes include a second target interdigital electrode, and a second gap is formed between a tip of the second target interdigital electrode away from the second bus bar and the first bus bar; The piezoelectric layer has a first cavity at a position corresponding to the first gap. The first cavity is recessed from the first side toward the second side, and the first cavity is connected to the first gap.

17. The resonator according to claim 16, characterized in that The first cavity passes through from the first side to the second side.

18. The resonator according to claim 16 or 17, characterized in that The first cavity has a first side surface and a second side surface opposite to each other in a first direction; The first side surface is flush with the end surface of the finger tip of the first target interdigital electrode, and the second side surface is flush with the side surface of the second bus bar facing the first bus bar; The first direction is parallel to an extending direction of the first target interdigital electrode.

19. The resonator according to any one of claims 16 to 18, characterized in that The first cavity extends toward the second target interdigital electrode.

20. The resonator according to any one of claims 16 to 19, characterized in that An angle α is formed between an extending direction of the first bus bar and each of the first interdigitated electrodes, where α≠90°.

21. The resonator according to claim 20, characterized in that An included angle α between an extending direction of the first bus bar and each of the first interdigital electrodes satisfies 45°≤α≤85°.

22. The resonator according to claim 20 or 21, characterized in that The first bus bar and the second bus bar are arranged in parallel.

23. The resonator according to any one of claims 16 to 22, characterized in that The resonator is used to generate a first-order antisymmetric mode when exciting the piezoelectric layer. The vibration direction of the first-order antisymmetric mode is parallel to a second direction. The second direction is parallel to the surface of the substrate and perpendicular to the first direction.

24. A filter, characterized in that include: A plurality of electrically connected resonators, at least one of the plurality of resonators being the resonator according to any one of claims 1 to 23.

25. An electronic device, characterized in that: include: amplifier; The resonator according to any one of claims 1 to 23, or the filter according to claim 24, wherein the resonator or the filter is electrically connected to the amplifier.

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