An acoustic resonator, a preparation method thereof, and a communication device

Abstract

The present invention relates to the technical field of resonators, and particularly relates to an acoustic wave resonator, a preparation method thereof, and a communication device. The acoustic wave resonator at least includes a support substrate, and a conductive layer, a piezoelectric thin film, and an interdigital transducer located on the support substrate; at least part of the interdigital transducer is disposed on the piezoelectric thin film; the conductive layer at least includes a bottom electrode; at least part of the piezoelectric thin film is disposed on the bottom electrode; the bottom electrode is smaller than the length of the aperture region of the interdigital transducer in the first direction, the target mode of the acoustic wave resonator is an acoustic wave mode excited under the action of a longitudinal electric field, the product of the pitch of the electrode fingers of the interdigital transducer and the resonance frequency of the acoustic wave resonator is less than the slow shear wave sound velocity of the support substrate, and by making the bottom electrode shrink into the piezoelectric thin film to avoid device short-circuit, the patterning process of the bottom electrode can be realized with simpler process steps, and the excitation of the bulk acoustic wave mode and the problems of spurious response and bulk acoustic wave energy leakage caused by it are also avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, and particularly to an acoustic wave resonator, a preparation method thereof, and a communication device. Background Art

[0002] With the development of wireless communication technology, low loss, large bandwidth, tunability, and temperature stability have become the common pursuit goals in the communication industry. However, neither the surface acoustic wave (SAW) resonator based on a piezoelectric hetero-substrate nor the bulk acoustic wave (BAW) resonator based on aluminum nitride or scandium-doped aluminum nitride thin film can meet the frequency or bandwidth requirements of the N77 band in the 5G frequency band. The acoustic wave mode excited by the longitudinal electric field shows great potential in terms of sound velocity and electromechanical coupling coefficient.

[0003] One type of acoustic wave resonator in the prior art is to form a suspended bottom electrode by back-etching the substrate to avoid parasitic bulk acoustic waves and leakage. Another type is to pattern the bottom electrode by etching the entire bottom electrode and piezoelectric thin film, and filling the etched area. However, both of the above two solutions have the disadvantages of high structural complexity and difficult forming and processing. Summary of the Invention

[0004] To solve the above technical problems, the present application discloses an acoustic wave resonator on the one hand, which includes a support substrate, and a conductive layer, a piezoelectric thin film, and an interdigital transducer located on the support substrate;

[0005] At least part of the interdigital transducer is disposed on the piezoelectric thin film;

[0006] The conductive layer at least includes a bottom electrode; at least part of the piezoelectric thin film is disposed on the bottom electrode;

[0007] The length of the bottom electrode in the first direction does not exceed the length of the aperture region of the interdigital transducer in the first direction, and the bottom electrode does not contact the interdigital transducer; the aperture region is the region where the electrode fingers of the interdigital transducer overlap; the first direction is the length direction of the electrode fingers of the interdigital transducer;

[0008] The target mode of the acoustic wave resonator is the acoustic wave mode excited by the action of the longitudinal electric field, and the product of the spacing between the electrode fingers of the interdigital transducer and the resonant frequency of the acoustic wave resonator is less than the slow shear wave sound velocity of the support substrate; the spacing between the electrode fingers of the interdigital transducer is the distance between the centers of adjacent electrode fingers on the same bus bar of the interdigital transducer.

[0009] Optionally, the interdigital transducer includes a first bus bar, a second bus bar, a plurality of first electrode fingers, and a plurality of second electrode fingers;

[0010] A plurality of first electrode fingers spaced apart by a first preset distance are provided on the first bus bar;

[0011] A plurality of second electrode fingers spaced apart by a second preset distance are provided on the second bus bar;

[0012] The plurality of first electrode fingers and the plurality of electrode fingers are arranged alternately along a second direction; the second direction is perpendicular to the first direction;

[0013] The aperture region is an area where the plurality of first electrode fingers and the plurality of second electrode fingers overlap;

[0014] The interdigital transducer further includes an air gap region, which is the region between the free end of the second electrode finger and the first bus bar, and the region between the free end of the first electrode finger and the second bus bar;

[0015] The bus bar of the interdigital transducer is in direct contact with the support substrate, or a piezoelectric thin film and a bottom electrode are provided between the bus bar of the interdigital transducer and the support substrate.

[0016] Optionally, the aperture region of the interdigital transducer is located on the piezoelectric thin film;

[0017] The length of the bottom electrode along the first direction below the aperture region does not exceed the length of the corresponding piezoelectric thin film along the first direction;

[0018] There are gaps with a third preset distance on both sides of the bottom electrode and the area of the adjacent interdigital transducer.

[0019] Optionally, the first bus bar and the second bus bar are directly provided on the top of the support substrate;

[0020] There is a fourth preset distance between the side surface of the piezoelectric thin film close to the aperture region and the adjacent bus bar.

[0021] Optionally, the end of the first electrode finger and / or the second electrode finger is aligned with or extends beyond the side surface of the piezoelectric thin film close to the aperture region.

[0022] Optionally, etching through holes are provided on the piezoelectric thin film;

[0023] The gaps with a third preset distance on both sides of the bottom electrode and the area of the adjacent interdigital transducer are communicated with the etching through holes.

[0024] Optionally, the conductive layer further includes a first region and a second region;

[0025] The first bus bar is located on the first region;

[0026] The second bus bar is located on the second region;

[0027] There is a gap with a fifth preset distance between adjacent regions among the first region, the bottom electrode, and the second region.

[0028] Optionally, the interdigital transducer further includes dummy finger electrodes;

[0029] The dummy finger electrodes are located outside the aperture region.

[0030] Optionally, a reflection grating is further included;

[0031] The reflection grating is located on the side of the interdigital transducer.

[0032] Optionally, a load member is further included;

[0033] The load member is located on the free ends of the electrode fingers of the interdigital transducer;

[0034] The thickness of the load member is 0.001 to 0.5 times the pitch of the electrode fingers of the interdigital transducer.

[0035] Optionally, the support substrate includes a stacked support layer and a high sound velocity layer;

[0036] The high sound velocity layer is a material that is easy to process; the material of the high sound velocity layer is any one of silicon carbide, diamond, diamond-like carbon, alumina, aluminum nitride, boron nitride, boron carbide, and silicon nitride with different crystal forms and different cut types;

[0037] The material of the support layer includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

[0038] Optionally, an intermediate dielectric layer is further provided between the support substrate and the bottom electrode, and the intermediate dielectric layer can be a single-layer material or a multi-layer material, including but not limited to one or more of silicon oxide, silicon nitride, polysilicon, amorphous silicon, alumina, and aluminum nitride.

[0039] Optionally, the bottom electrode is a combination of one or more of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

[0040] Optionally, the material of the piezoelectric thin film is one or a combination of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate, or lead magnesium niobate-titanate.

[0041] Optionally, the support substrate is one or a combination of more than one of silicon carbide, diamond, diamond-like, silicon, sapphire, aluminum nitride, boron nitride, boron carbide, and silicon nitride with different crystal forms and different cutting types.

[0042] Optionally, the thickness of the high sound velocity layer is greater than or equal to 0.5 times the pitch of the electrode fingers of the interdigital transducer;

[0043] The thickness of the piezoelectric thin film is 0.1 to 2 times the pitch of the electrode fingers of the interdigital transducer;

[0044] The thickness of the bottom electrode is 0.005 to 0.5 times the pitch of the electrode fingers of the interdigital transducer;

[0045] The thickness of the interdigital transducer is 0.005 to 0.5 times the pitch of the electrode fingers of the interdigital transducer.

[0046] Optionally, the target mode is one of a zero-order longitudinal leaky surface acoustic wave, a higher-order Lamb wave, a higher-order horizontal shear wave, and a higher-order Rayleigh mode.

[0047] On the other hand, the present application also discloses a method for manufacturing the above acoustic wave resonator, which includes:

[0048] Providing a heterostructure; the heterostructure includes a support substrate, a conductive material layer, and a piezoelectric material layer sequentially arranged from bottom to top;

[0049] Patterning the piezoelectric material layer to form the piezoelectric thin film, and the piezoelectric thin film includes an etching region;

[0050] Etching the conductive material layer based on the etching region to form the conductive layer on the support substrate;

[0051] Forming the interdigital transducer.

[0052] Optionally, the step of providing a heterostructure includes:

[0053] Providing a piezoelectric crystal with the conductive material layer on its surface;

[0054] Performing ion implantation from the surface of the conductive material layer into the piezoelectric crystal;

[0055] Providing a support substrate;

[0056] Bonding the support substrate and the conductive material layer, and then performing annealing and peeling treatment to obtain the heterostructure.

[0057] On the other hand, the present application also discloses a communication device, which includes the above acoustic wave resonator;

[0058] The communication device includes at least one of a filter, a duplexer, and a multiplexer.

[0059] An acoustic wave resonator provided by an embodiment of the present application includes a support substrate, a conductive layer, a piezoelectric thin film, and an interdigital transducer located on the support substrate; at least a part of the interdigital transducer is disposed on the piezoelectric thin film; the conductive layer includes at least a bottom electrode; at least a part of the piezoelectric thin film is disposed on the bottom electrode; the length of the bottom electrode in a first direction does not exceed the length of the aperture region of the interdigital transducer in the first direction, and the bottom electrode does not contact the interdigital transducer; the aperture region is the region where the electrode fingers of the interdigital transducer overlap; the first direction is the length direction of the electrode fingers of the interdigital transducer; the target mode of the acoustic wave resonator is an acoustic wave mode excited under the action of a longitudinal electric field, and the product of the pitch of the electrode fingers of the interdigital transducer and the resonance frequency of the acoustic wave resonator is less than the slow shear wave sound velocity of the support substrate; the pitch of the electrode fingers of the interdigital transducer is the distance between the centers of adjacent electrode fingers on the same bus bar of the interdigital transducer. In this way, the bottom electrode that does not exceed the aperture region can be etched through an etching through hole or an etching region provided on the piezoelectric thin film, thereby not only avoiding the excitation of the bulk acoustic wave mode and the problems of spurious response and bulk acoustic wave energy leakage caused thereby, but also making the entire device have the advantages of simple structure and easy processing and forming. Description of the Drawings

[0060] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0061] Figure 1 is a top view of an exemplary first acoustic wave resonator;

[0062] Figure 2 is Figure 1 a schematic diagram of the A1B1 cross-section of the shown acoustic wave resonator;

[0063] Figure 3 is a top view of an exemplary Comparative Example 1;

[0064] Figure 4 is Figure 3 a schematic diagram of the A2B2 cross-section of the shown Comparative Example 1;

[0065] Figure 5 is a simulation admittance curve of an exemplary Comparative Example 1;

[0066] Figure 6 isFigure 5 The corresponding vibration mode diagram;

[0067] Figure 7 It is a top view of the exemplary Comparative Example 2;

[0068] Figure 8 is Figure 7 A schematic diagram of the A3B3 cross-section of the shown Comparative Example 2;

[0069] Figure 9 It is a cross-sectional view of the exemplary second acoustic wave resonator;

[0070] Figure 10 is Figure 9 The corresponding simulated admittance curve;

[0071] Figure 11 is Figure 10 The corresponding vibration mode diagram;

[0072] Figure 12 is Figure 9 The simulated admittance curves of acoustic wave resonators corresponding to different etching angles;

[0073] Figure 13 is for Figure 12 The admittance ratio curves corresponding to different etching angles after extracting and processing the simulated admittance curves in [[ ]];

[0074] Figure 14 It is a cross-sectional view of the exemplary third acoustic wave resonator;

[0075] Figure 15 It is a top view of the exemplary fourth acoustic wave resonator;

[0076] Figure 16 It is a top view of the exemplary fifth acoustic wave resonator;

[0077] Figure 17 is Figure 16 A schematic diagram of the A4B4 cross-section of the shown acoustic wave resonator;

[0078] Figure 18 It is a top view of the exemplary sixth acoustic wave resonator;

[0079] Figure 19 It is a top view of the exemplary seventh acoustic wave resonator;

[0080] Figure 20 It is a top view of the exemplary eighth acoustic wave resonator;

[0081] Figure 21 is Figure 20 A schematic diagram of the A5B5 cross-section of the shown acoustic wave resonator;

[0082] Figure 22 It is a top view of an exemplary ninth acoustic wave resonator;

[0083] Figure 23 It is a top view of an exemplary tenth acoustic wave resonator;

[0084] Figure 24 It is Figure 23 A schematic diagram of the A6B6 cross-section of the acoustic wave resonator shown;

[0085] Figure 25 It is a top view of an exemplary eleventh acoustic wave resonator;

[0086] Figure 26 It is Figure 25 A schematic diagram of the A7B7 cross-section of the acoustic wave resonator shown;

[0087] Figure 27 It is Figure 26 The corresponding simulated admittance curve;

[0088] Figure 28 It is a top view of an exemplary twelfth acoustic wave resonator;

[0089] Figure 29 It is a top view of an exemplary thirteenth acoustic wave resonator;

[0090] Figure 30 It is Figure 29 A schematic diagram of the A8B8 cross-section of the acoustic wave resonator shown;

[0091] Figure 31 It is Figure 30 The corresponding simulated admittance curve;

[0092] Figure 32 It is a top view of an exemplary fourteenth acoustic wave resonator;

[0093] Figure 33 It is a top view of an exemplary fifteenth acoustic wave resonator;

[0094] Figure 34 It is Figure 33 A schematic diagram of the A8B8 cross-section of the acoustic wave resonator shown;

[0095] Figure 35 It is Figure 34 The corresponding simulated admittance curve with and without a load component;

[0096] Figure 36 It is a schematic diagram of the preparation process of an exemplary acoustic wave resonator;

[0097] Figures 37 - 44 It is a schematic diagram of the structure during the preparation of an exemplary acoustic wave resonator.

[0098] The following is a supplementary description of the drawings:

[0099] 1 - Support substrate; 2 - Piezoelectric thin film; 201 - Etched through-hole; 202 - Etched area; 3 - Conductive layer; 301 - Bottom electrode; 302 - First region; 303 - Second region; 4 - Interdigital transducer; 401 - First bus bar; 402 - Second bus bar; 403 - First electrode finger; 404 - Second electrode finger; 405 - Aperture region; 406 - Air gap region; 407 - False finger electrode; 408 - Reflection grating; 5 - Intermediate dielectric layer; 6 - Load member; 7 - Conductive material layer; 8 - Piezoelectric material layer. Specific embodiments

[0100] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0101] As used herein, the term "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order different from those illustrated or described herein.

[0102] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as every value therebetween. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. For example, a specified range from "1 to 10" should be considered to include any and all sub-ranges between the minimum value 1 and the maximum value 10. Exemplary sub-ranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0103] Please refer to Figures 1 - 2 , Figure 1 is a top view of a first exemplary acoustic resonator of the present application; Figure 2 is Figure 1 a schematic cross-sectional view of the acoustic resonator shown in A1 B1. An embodiment of the present application provides an acoustic resonator, which includes a support substrate 1, and a conductive layer 3, a piezoelectric thin film 2, and an interdigital transducer 4 located on the support substrate 1; at least part of the interdigital transducer 4 is disposed on the piezoelectric thin film 2; the conductive layer 3 at least includes a bottom electrode 301; at least part of the piezoelectric thin film 2 is disposed on the bottom electrode 301; the length of the bottom electrode 301 in a first direction does not exceed the length of the aperture region 405 of the interdigital transducer 4 in the first direction, and the bottom electrode 301 does not contact the interdigital transducer 4; the aperture region 405 is the region where the electrode fingers of the interdigital transducer 4 overlap; the first direction is the length direction of the electrode fingers of the interdigital transducer 4, that is, the y direction as shown in Figure 1 . The target mode of the acoustic resonator is an acoustic mode excited under the action of a longitudinal electric field, and the product of the pitch of the electrode fingers of the interdigital transducer 4 and the resonance frequency of the acoustic resonator is less than the slow shear wave sound velocity of the support substrate 1; the pitch of the electrode fingers of the interdigital transducer 4 is the distance between the centers of adjacent electrode fingers on the same bus bar of the interdigital transducer 4.

[0104] When there is an overlapping part between the bottom electrode 301 and the interdigital transducer 4 outside the aperture region 405, a parasitic mode of the bulk acoustic wave will be formed. At the same time, for single-crystal piezoelectric materials with a large electromechanical coupling coefficient, it is very difficult to form a patterned bottom electrode 301. Therefore, on the premise of not affecting the main mode, forming a patterned bottom electrode 301 with a simple process is the key to realizing a high-performance high-frequency wide-band filter.

[0105] To avoid parasitic body waves, the bottom electrode 301 of the acoustic resonator provided in this embodiment does not extend beyond the aperture region 405, and the bottom electrode 301 also does not extend beyond the piezoelectric thin film 2, thus naturally avoiding the device short - circuit situation. The patterning process of the bottom electrode 301 can also be achieved with simpler technological steps. Moreover, the high - sound - velocity mode excited by the longitudinal electric field is used as the target mode, and the support substrate 1 with a high sound velocity confines the target mode on the substrate surface.

[0106] Exemplarily, the interdigital transducer 4 includes a first bus bar 401, a second bus bar 402, a plurality of first electrode fingers 403, and a plurality of second electrode fingers 404; a plurality of first electrode fingers 403 spaced apart by a first preset distance are provided on the first bus bar 401; a plurality of second electrode fingers 404 spaced apart by a second preset distance are provided on the second bus bar 402; the plurality of first electrode fingers 403 and the plurality of electrode fingers are arranged alternately along a second direction; the second direction is perpendicular to the first direction; the aperture region 405 is the region where the plurality of first electrode fingers 403 and the plurality of second electrode fingers 404 overlap; the interdigital transducer 4 further includes an air - gap region 406, and the air - gap region 406 is the region between the free end of the second electrode finger 404 and the first bus bar 401, and the region between the free end of the first electrode finger 403 and the second bus bar 402. Optionally, the second direction can be, for example, Figure 1 the x - direction as shown.

[0107] Exemplarily, the support substrate 1 includes a stacked support layer and a high - sound - velocity layer; the high - sound - velocity layer is a material that is easy to form and process, and the material of the high - sound - velocity layer is any one of silicon carbide, diamond, diamond - like carbon, alumina, aluminum nitride, boron nitride, boron carbide, and silicon nitride with different crystal forms and different cut types; the material of the support layer includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

[0108] Exemplarily, an intermediate dielectric layer 5 is further provided between the support substrate 1 and the bottom electrode 301. The intermediate dielectric layer 5 can be a single - layer material or a multi - layer material, including but not limited to one or more of silicon oxide, silicon nitride, polysilicon, amorphous silicon, alumina, and aluminum nitride.

[0109] Exemplarily, the bottom electrode 301 is a combination of one or more of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper - aluminum alloy, aluminum - silicon alloy, doped silicon, silicon carbide, and gallium nitride.

[0110] Exemplarily, the material of the piezoelectric thin film 2 is one or a combination of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium - doped aluminum nitride, lead zirconate titanate, or lead magnesium niobate - titanate.

[0111] Exemplarily, the support substrate 1 is one or a combination of more than one of silicon carbide, diamond, diamond-like, silicon, sapphire, aluminum nitride, boron nitride, boron carbide, and silicon nitride with different crystal forms and cut types.

[0112] Exemplarily, the pitch of the electrode fingers of the interdigital transducer 4 can be denoted as λ.

[0113] Exemplarily, the thickness of the high acoustic velocity layer can be greater than or equal to 0.5λ; the thickness of the piezoelectric thin film 2 can range from 0.1λ to 2λ; the thickness of the bottom electrode 301 can range from 0.005λ to 0.5λ; the thickness of the interdigital transducer 4 can range from 0.005λ to 0.5λ. In this way, other performance of the acoustic wave device can be ensured while avoiding the excitation of the bulk acoustic wave mode and the resulting spurious response and bulk acoustic wave energy leakage.

[0114] Exemplarily, the target mode is one of the zero-order longitudinal leaky surface acoustic wave, the higher-order Lamb wave, the higher-order horizontal shear wave, and the higher-order Rayleigh mode.

[0115] The conductive layer 3 of the acoustic wave resonator provided by the embodiment of the present application can only include the bottom electrode 301. The bottom electrode 301 can only be located below the aperture region 405 and does not exceed the aperture region 405 (that is, the piezoelectric thin film 2 and the conductive layer 3 in the remaining regions except the aperture region 405 will be etched away). It can also include other regions spaced from the bottom electrode 301 in the first direction (please refer to Figure 1 , and this other region can be a conductive region distributed around the interdigital transducer 4). The bottom electrode 301 in the above two conductive layers 3 belongs to a suspended bottom electrode, which is not only simple in structure but also convenient to prepare. Based on the different positions of the interdigital transducer 4, the bus bar of the interdigital transducer 4 can be in direct contact with the support substrate 1, or the piezoelectric thin film 2 and the bottom electrode 301 can be provided between the bus bar of the interdigital transducer 4 and the support substrate 1. In addition, according to the shape, size, and position of the piezoelectric thin film 2, as well as the structure of the interdigital transducer 4 and the length of the electrode fingers, etc., the acoustic wave resonator can include various structures, which will be specifically described below. However, in order to better reflect the beneficial effects of the acoustic wave resonator provided by the embodiment of the present application, some comparative structures will be described first below.

[0116] Please refer to Figure 3 and 4 , which are respectively the top view of Comparative Example 1, and Figure 3Schematic diagram of the A2B2 cross-section. The resonator of Comparative Example 1 includes a support substrate 1, an intermediate dielectric layer 5, a bottom electrode 301, a piezoelectric thin film 2, and an interdigital transducer 4 arranged in sequence from bottom to top. It can be seen that the bottom electrode 301 and the piezoelectric thin film 2 cover the entire top surface of the support substrate 1. Specifically, the material of the support substrate 1 is 4H-SiC, the material of the intermediate dielectric layer 5 is silicon oxide, and the thickness is 200 nm; the piezoelectric thin film 2 is X-cut lithium niobate, and the thickness is 200 nm; the material of the interdigital transducer 4 is aluminum / tungsten, and the thickness is 78 / 25 nm, λ is 1.54 μm, and the target mode is the SH1 mode. Subsequent relevant calculations can be performed on it, and the following can be obtained as Figure 5 the shown simulated admittance curve. It can be seen that there are resonance peaks caused by leaked parasitic bulk acoustic wave modes near the resonance frequency and the anti-resonance frequency of the SH1 mode. Please refer to Figure 5 the corresponding vibration mode diagram, that is Figure 6 It can be seen that there are obvious leaked bulk acoustic waves in the bus bar and the air gap region 406.

[0117] Please refer to Figure 7 and 8 which are respectively the top view of Comparative Example 2, and Figure 7 the schematic diagram of the A3B3 cross-section in . The resonator of Comparative Example 2 includes a support substrate 1, an intermediate dielectric layer 5, a bottom electrode 301, a piezoelectric thin film 2, and an interdigital transducer 4 arranged in sequence from bottom to top. It can be seen that the difference between it and Comparative Example 1 is that the bus bars of the interdigital transducer 4 are all in direct contact with the intermediate dielectric layer 5, and the piezoelectric thin film 2 and the bottom electrode 301 are only located below the aperture region 405, but the side surface of the bottom electrode 301 is in direct contact with the interdigital transducer 4, which will cause the device to short-circuit. From the above Comparative Example 1 and Comparative Example 2, it can be seen that the acoustic resonator provided in the embodiment of the present application has a suspended bottom electrode 301, and the bottom electrode 301 is not in direct contact with the interdigital transducer 4, so that not only the problem of bulk acoustic wave leakage can be avoided, but also the short-circuit problem can be avoided, and the overall structure is simple and convenient for forming and processing.

[0118] According to the setting position of the bus bar of the interdigital transducer 4, the acoustic resonator provided in the present application can be divided into two categories. In the first category of acoustic resonators, the bus bar of the interdigital transducer 4 is in direct contact with the support substrate 1. In the second category of acoustic resonators, the bus bar of the interdigital transducer 4 is not in direct contact with the support substrate 1, and there are also a piezoelectric thin film 2 and a bottom electrode 301 between them.

[0119] The first category of acoustic resonators will be described first below. Please continue to refer to Figure 1 and Figure 2, the first bus bar 401 and the second bus bar 402 are directly disposed on the top of the support substrate 1; there is a fourth preset distance between the end of the piezoelectric film 2 close to the aperture region 405 and the adjacent bus bar; the aperture region 405 of the interdigital transducer 4 is located on the piezoelectric film 2; the length of the bottom electrode 301 below the aperture region 405 along the first direction does not exceed the length of the corresponding piezoelectric film 2 along the first direction; there are gaps with a third preset distance between both sides of the bottom electrode 301 and the regions of the adjacent interdigital transducers 4. Specifically, the gap between the bottom electrode 301 and the bus bar is formed by etching after the piezoelectric film 2 is formed. Due to the existence of this gap, the short circuit between the bottom electrode 301 and the interdigital transducer 4 is avoided. Optionally, the etching through hole 201 or the etching region 202 can be formed in the piezoelectric film 2 first, and then the corresponding material layer of the bottom electrode 301 can be etched based on the etching through hole 201 or the etching region 202 to form the gap. Optionally, the etching angle corresponding to the side surface of the piezoelectric film 2 near the air gap region 406 can be an acute angle as shown in Figure 2 shown, or it can also be a right angle as shown in Figure 9 .

[0120] Exemplarily, for the structure shown in Figure 9 , the material of the support substrate 1 is 4H-SiC, the material of the intermediate dielectric layer 5 is silicon oxide, and the thickness is 200 nm; the piezoelectric film 2 is X-cut lithium niobate, and the thickness is 200 nm; the material of the interdigital transducer 4 is aluminum / tungsten, and the thickness is 78 / 25 nm, λ is 1.54 μm, the material of the bottom electrode 301 is tungsten, and the thickness is 100 nm, and the target mode is the SH1 mode. After subsequent related calculations, the simulated admittance curve shown in Figure 10 can be obtained. It can be seen that compared with the structure shown in Figure 5 , the admittance of the target mode is relatively large, there is no parasitic bulk acoustic wave mode, and there is a longitudinal leaky surface acoustic wave (LL-SAW) mode in the low frequency band. Please refer to Figure 10 the corresponding vibration mode diagram, that is, Figure 11 , it can be seen that there is no leaking bulk acoustic wave in the bus bar and the air gap region 406.

[0121] For piezoelectric films 2 with different etching angles, it will also affect the performance of the device. Taking Figure 9Taking the structure shown as an example, the material of the support substrate 1 is 4H-SiC, the material of the intermediate dielectric layer 5 is silicon oxide, and the thickness is 200 nm; the piezoelectric thin film 2 is X-cut lithium niobate, and the thickness is 200 nm; the material of the interdigital transducer 4 is aluminum / tungsten, and the thickness is 78 / 25 nm, λ is 1.54 μm, the material of the bottom electrode 301 is tungsten, and the thickness is 100 nm. The target mode is the SH1 mode, and the parasitic mode is the LL-SAW. When the etching angles are 45°, 60°, 70°, 80°, 85°, and 90° respectively, relevant calculations are performed on the acoustic wave resonators corresponding to these etching angles, and the results can be obtained as follows Figure 12 the simulated admittance curves shown. Further, from Figure 12 the admittance ratios of the SH1 mode and the LL-SAW mode corresponding to different etching angles extracted, the results can be obtained as Figure 13 . It can be seen that the larger the etching angle, the larger the admittance ratio of the target mode. When the etching angle is 80°, the admittance ratio of the parasitic mode is relatively small and the admittance ratio of the target mode is still relatively large. At this time, the admittance ratio of the parasitic mode drops by 8.2 dB compared to 90°, while the target mode only drops by 2 dB. Therefore, by selecting an appropriate etching angle, it is also helpful to suppress the parasitic mode.

[0122] In an exemplary embodiment, please refer to Figure 2 , an intermediate dielectric layer 5 is provided between the support substrate 1 and the bottom electrode 301. Optionally, please refer to Figure 14 , the support substrate 1 is in direct contact with the bottom electrode 301, and no intermediate dielectric layer 5 is provided therebetween.

[0123] In another exemplary embodiment, please refer to Figure 15 , compared with Figure 1 , the piezoelectric thin film 2 and the conductive layer 3 outside the aperture region 405 are etched away, that is, only the piezoelectric thin film 2 and the bottom electrode 301 exist below the aperture region 405.

[0124] In another exemplary embodiment, please refer to Figure 16 , and Figure 17 the schematic diagram corresponding to the A4B4 cross-section shown in Figure 16 . The end of the first electrode finger 403 extends beyond the side of the piezoelectric thin film 2 close to the aperture region 405, or the end of the second electrode finger 404 extends beyond the side of the piezoelectric thin film 2 close to the aperture region 405, or the ends of both the first electrode finger 403 and the second electrode finger 404 extend beyond the side of the piezoelectric thin film 2 close to the aperture region 405. Of course, please refer to Figure 9 , the end of the first electrode finger 403 or the second electrode finger 404 can also be aligned with the side of the piezoelectric thin film 2 close to the aperture region 405.

[0125] In another exemplary embodiment, please refer to Figure 18 , the acoustic resonator further includes a reflection grating 408; the reflection grating 408 is located on the side of the interdigital transducer 4. This is beneficial to reducing the in-plane leakage of acoustic waves to the left and right sides.

[0126] In another exemplary embodiment, the interdigital transducer 4 further includes dummy finger electrodes 407; the dummy finger electrodes 407 are located outside the aperture region 405, which is beneficial to reducing the in-plane leakage of acoustic waves to the front and back sides. Specifically, the number of the dummy finger electrodes 407 is the same as the number of electrode fingers in the interdigital transducer 4, and a dummy finger electrode 407 is provided on the opposite side of each electrode finger, and there is a preset interval distance between the free end of the electrode finger and the free end of the dummy finger electrode 407. Specifically, the piezoelectric thin film 2 is provided with an etched through hole 201, and the etched through hole 201 may include a gap region between the first region 302 and the bottom electrode 301, and a gap region between the second region 303 and the bottom electrode 301. The interval width between the dummy finger electrode 407 and the corresponding electrode finger is greater than or equal to the interval distance between adjacent thin film regions.

[0127] In another exemplary embodiment, the acoustic resonator further includes a load member 6; the load member 6 is located on the free ends of the electrode fingers of the interdigital transducer 4. For example, load members 6 are provided on the free ends of the first electrode finger 403 and the second electrode finger 404. Optionally, two load members 6 are provided on the same electrode finger, one load member 6 is located on the free end of the electrode finger, and the other load member 6 is located in the region corresponding to the free end of the electrode finger and the adjacent electrode finger. Optionally, the thickness of the load member 6 is 0.001 to 0.5 times the pitch of the electrode fingers of the interdigital transducer 4.

[0128] In another exemplary embodiment, please refer to Figure 19 , the shape of the bottom electrode 301 may be limited to a rectangle, or may be other shapes such as an ellipse.

[0129] The above is the description of the first type of acoustic resonator. The following will describe the second type of acoustic resonator. In the second type of acoustic resonator, the bus bar of the interdigital transducer 4 does not directly contact the support substrate 1, and there are also a piezoelectric thin film 2 and a bottom electrode 301 therebetween.

[0130] Please refer to Figure 20, the conductive layer 3 further includes a first region 302, a second region 303, and a conductive region located around the interdigital transducer 4; the first bus bar 401 is located on the first region 302; the second bus bar 402 is located on the second region 303; there is a gap with a fifth preset distance between adjacent regions among the first region 302, the bottom electrode 301, and the second region 303, and the above-mentioned conductive region surrounds the first region 302, the bottom electrode 301, and the second region 303 and is not connected to these three regions. At this time, according to the regional division of the conductive layer 3, the piezoelectric thin film 2 located thereon can also be divided into four thin film regions in the same division method, and there is a thin film region on each of the first region 302, the second region 303, the bottom electrode 301, and the conductive region, and these four thin film regions are not connected to each other. Further, please refer to Figure 21 , which shows Figure 20 a schematic diagram of the A5B5 cross-section of, it can be seen that most of the interdigital transducer 4 is located on the piezoelectric thin film 2, but a part of the electrode fingers in the air gap region falls on the piezoelectric thin film 2, and the other part falls on the intermediate dielectric layer 5. Since the material of the conductive layer 3 is usually metal and the metal has good thermal conductivity, this structure helps to increase the area of the conductive layer 3, is beneficial to heat dissipation, and will not cause parasitic surface acoustic wave leakage. Most of the interdigital transducer 4 is located on the surface at the same height, which is also beneficial to the lithography process.

[0131] In an exemplary embodiment, please refer to Figure 22 , and Figure 20 Compared with the surface acoustic wave resonator shown, the surface acoustic wave resonator in this example does not have the above-mentioned conductive region located around the interdigital transducer 4, that is, the conductive layer 3 only includes the first region 302, the second region 303, and the bottom electrode 301. Correspondingly, the piezoelectric thin film 2 is also divided into three thin film regions, that is, there is a thin film region on each of the first region 302, the second region 303, and the bottom electrode 301, and these three thin film regions are not connected to each other.

[0132] In another exemplary embodiment, please refer to Figure 23 , and Figure 24 shown Figure 23Schematic diagram corresponding to the A6B6 cross-section. The interdigital transducer 4 further includes dummy finger electrodes 407, which helps reduce in-plane leakage of acoustic waves to the front and back sides. Specifically, the number of the dummy finger electrodes 407 is the same as the number of electrode fingers in the interdigital transducer 4. A dummy finger electrode 407 is provided on the opposite side of each electrode finger, and there is a preset spacing distance between the free ends of the electrode fingers and the free ends of the dummy finger electrodes 407. Specifically, the piezoelectric thin film 2 is provided with etched through-holes 201, and the etched through-holes 201 may include a gap region between the first region 302 and the bottom electrode 301, and a gap region between the second region 303 and the bottom electrode 301. The spacing width between the dummy finger electrode 407 and the corresponding electrode finger is greater than or equal to the spacing distance between adjacent thin film regions.

[0133] In another exemplary embodiment, please refer to Figure 25 , and Figure 26 as shown in Figure 25 Schematic diagram corresponding to the A7B7 cross-section. The difference between this example and Figure 23 is that the three thin film regions of the piezoelectric thin film 2 are connected, and multiple etched through-holes 201 are provided on the piezoelectric thin film regions corresponding to the spacing regions between multiple unconnected conductive regions of the conductive layer 3, and these etched through-holes 201 are connected to the spacing regions between adjacent conductive regions. That is to say, the strip-shaped through-holes penetrating the piezoelectric thin film 2 in the above Figure 23 are replaced with multiple discrete small holes. This structure helps reduce the etching area and further avoid device short-circuit. Optionally, the shape of the etched through-holes 201 can be a rectangle as shown in Figure 25 , or a circle, etc., which is not limited here. Specifically, the material of the support substrate 1 is 4H-SiC, the material of the intermediate dielectric layer 5 is silicon oxide, and the thickness is 200 nm; the piezoelectric thin film 2 is X-cut lithium niobate, and the thickness is 200 nm; the material of the interdigital transducer 4 is aluminum / tungsten, and the thickness is 78 / 25 nm, λ is 1.54 μm, the material of the bottom electrode 301 is tungsten, and the thickness is 100 nm, and the target mode is the SH1 mode. After subsequent relevant calculations, the simulated admittance curve as shown in Figure 27 can be obtained. It can be seen that no parasitic bulk acoustic wave mode will occur even if the conductive layer 3 is divided into multiple discrete conductive regions.

[0134] In another exemplary embodiment, please refer to Figure 28, the etched vias 201 can not only be located in the air gap region 406 of the interdigital transducer 4, but also in the piezoelectric thin film 2 corresponding to the bus bar. At this time, the conductive layer 3 below the bus bar region and the air gap region 406 is completely etched. That is, the etched vias 201 provided in this application are always located in the spacer region between the corresponding adjacent conductive regions in the piezoelectric thin film 2. Optionally, based on the shape of the discrete conductive regions, etched vias 201 can also be provided in the piezoelectric thin film 2 corresponding to the peripheral region of the interdigital transducer 4, such as Figure 28 shown, a strip-shaped etched via 201 can also be provided in the regions of the piezoelectric thin film 2 corresponding to both sides of the interdigital transducer 4 respectively. Optionally, the etched via 201 can be as Figure 28 shown in a circular shape, or can be as Figure 29 shown in a square shape, or other shapes, which are not limited here. Please refer to Figure 30 , which is Figure 29 the schematic diagram corresponding to the A8B8 cross-section in Figure 26 . Compared with Figure 26 , the spacing distance between the bottom electrode 301 and the adjacent conductive region is larger, so that there is no conductive region below the bus bar. Specifically, the material of the support substrate 1 is 4H-SiC, the material of the intermediate dielectric layer 5 is silicon oxide, and the thickness is 200 nm; the piezoelectric thin film 2 is X-cut lithium niobate, and the thickness is 200 nm; the material of the interdigital transducer 4 is aluminum / tungsten, and the thickness is 78 / 25 nm, λ is 1.54 μm, the material of the bottom electrode 301 is tungsten, and the thickness is 100 nm, and the target mode is SH1 mode. After subsequent relevant calculations, the simulated admittance curve as Figure 31 shown can be obtained. It can be seen that when there is no conductive region below the bus bar and the air gap region 406, there will be no parasitic bulk acoustic wave mode.

[0135] In another exemplary embodiment, please refer to Figure 32 , an etched via 201 is provided in the air gap region corresponding to the end of each electrode finger. The etched via 201 is also located on the piezoelectric thin film 2 corresponding to the spacer region between the adjacent conductive regions. The length of the etched via 201 along the second direction can be greater than the width of the electrode finger and less than λ.

[0136] In another exemplary embodiment, please refer to Figure 33 , and Figure 24 shown is Figure 33Schematic diagram corresponding to the A9B9 cross-section. The acoustic wave resonator further includes a load member 6; the load member 6 is located at the free ends of the electrode fingers of the interdigital transducer 4. For example, load members 6 are provided at the free ends of the first electrode finger 403 and the second electrode finger 404. Optionally, two load members 6 are provided on the same electrode finger, one load member 6 is located at the free end of the electrode finger, and the other load member 6 is located in the region corresponding to the free ends of the electrode finger and the adjacent electrode finger. Optionally, the thickness of the load member 6 is 0.001 to 0.5 times the pitch of the electrode fingers of the interdigital transducer 4. Specifically, for Figure 34 the structure shown, the material of the support substrate 1 is 4H-SiC, the material of the intermediate dielectric layer 5 is silicon oxide, and the thickness is 200 nm; the piezoelectric thin film 2 is X-cut lithium niobate, and the thickness is 200 nm; the material of the interdigital transducer 4 is aluminum / tungsten, and the thickness is 78 / 25 nm, λ is 1.54 μm, the material of the bottom electrode 301 is tungsten, and the thickness is 100 nm, the material of the load member 6 is tungsten, the length is 0.3λ, and the thickness is 10 nm. The target mode is the SH1 mode. And a structure without the load member 6 is provided Figure 34 as shown. Subsequent relevant calculations can be performed on it, and the simulated admittance curve as shown in Figure 35 can be obtained. It can be seen that the load member 6 can effectively reduce the lateral high-order mode between the resonant frequency and the anti-resonant frequency.

[0137] It should be noted that in the second type of acoustic wave resonator, the etching angle corresponding to the piezoelectric thin film 2 can be selected as needed, and its range can be 45 to 90°. An intermediate dielectric layer 5 can be provided between the support substrate 1 and the bottom electrode 301, or the intermediate dielectric layer 5 can be not provided. The free end of the electrode finger can be aligned with or extend beyond the side surface adjacent to the piezoelectric thin film 2. Optionally, the shape of each partition of the conductive layer 3 can be a rectangle as shown in Figure 20 or other shapes (such as an ellipse). Optionally, reflection gratings 408 can be provided on both sides of the interdigital transducer 4.

[0138] This solution proposes to use the high acoustic velocity mode excited by the longitudinal electric field as the target mode, and use the support substrate 1 with high acoustic velocity to confine the target mode on the substrate surface. In order to avoid parasitic body acoustic waves, the bottom conductive layer 3 is locally etched through an etching hole or an etching area, thereby forming a patterned suspended bottom electrode. After etching, the area of the suspended bottom electrode is smaller than the area of the piezoelectric thin film 2, naturally avoiding the device short-circuit situation. By controlling the angle of the etched edge of the piezoelectric thin film 2, the suppression of parasitic modes can also be achieved. Therefore, this solution can realize the patterning of the suspended bottom electrode with simpler process steps, thereby avoiding parasitic body acoustic wave modes.

[0139] Please refer to Figure 36 , this embodiment of the present application also provides a method for manufacturing the above-mentioned acoustic wave resonator, which includes:

[0140] S3601: Provide a heterostructure; the heterostructure includes a support substrate 1, a conductive material layer 7, and a piezoelectric material layer 8 arranged in sequence from bottom to top.

[0141] Exemplarily, the top view of the heterostructure can be as Figure 37 shown, and the cross-sectional view of the heterostructure can be as Figure 38 shown. Specifically, Figure 38 shown is Figure 37 the schematic diagram corresponding to the A10B10 cross-section of. Step S3601 can be specifically described as: providing a piezoelectric crystal with the conductive material layer 7 on its surface; performing ion implantation from the surface of the conductive material layer 7 into the piezoelectric crystal; providing a support substrate 1; bonding the support substrate 1 with the conductive material layer and then performing annealing and peeling treatment to obtain the heterostructure. Of course, the heterostructure can also be formed by a direct bonding method.

[0142] Exemplarily, the support substrate 1 includes a stacked support layer and a high sound velocity layer; the high sound velocity layer is a material that is easy to form and process, and the material of the high sound velocity layer is any one of silicon carbide, diamond, diamond-like, alumina, aluminum nitride, boron nitride, boron carbide, and silicon nitride with different crystal forms and different cutting types; the material of the support layer includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

[0143] Exemplarily, an intermediate dielectric layer 5 is further provided between the support substrate 1 and the bottom electrode 301. The intermediate dielectric layer 5 can be a single-layer material or a multi-layer material, including but not limited to one or more of silicon oxide, silicon nitride, polysilicon, amorphous silicon, alumina, and aluminum nitride.

[0144] Exemplarily, the material of the conductive material layer 7 is one or a combination of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

[0145] Exemplarily, the material of the piezoelectric material layer 8 is one or a combination of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate, or lead magnesium niobate-titanate.

[0146] Exemplarily, the support substrate 1 is one or a combination of silicon carbide, diamond, diamond-like, silicon, sapphire, aluminum nitride, boron nitride, boron carbide, and silicon nitride with different crystal forms and different cutting types.

[0147] S3603: Pattern the piezoelectric material layer 8 to form the piezoelectric thin film 2, and the piezoelectric thin film 2 includes an etching region 202.

[0148] S3605: Etch the conductive material layer 7 based on the etching region 202 to form the bottom electrode 301 on the support substrate 1.

[0149] Exemplarily, please refer to Figure 39 and Figure 40 , Figure 40 as shown in Figure 39 is a schematic diagram corresponding to the A11 B11 cross-section of Figure 41 and Figure 42 , Figure 42 as shown in Figure 41 is a schematic diagram corresponding to the A12B12 cross-section of

[0150] Subsequently, continue to etch the conductive material layer 7 based on the etching region 202, so as to not only etch away the conductive material layer 7 corresponding to the etching region 202, but also etch away a part of the conductive material layer 7 under the piezoelectric thin film 2, so that there are gaps on both sides of the formed bottom electrode 301 and the side surfaces of the corresponding piezoelectric thin films 2, avoiding short circuits between the interdigital transducer 4 and the bottom electrode 301. Figure 28 、 Figure 29 、 Figure 32 or Figure 33 shown in the resonator.

[0151] S3607: Form the interdigital transducer 4.

[0152] Exemplarily, step S3607 can be specifically described as depositing a metal layer and patterning the metal layer to obtain the interdigital transducer 4 as shown in Figure 43 . Please refer to Figure 44 , which shows Figure 43 is a schematic diagram corresponding to the A13B13 cross-section of

[0153] Exemplarily, the pitch of the electrode fingers of the interdigital transducer 4 can be denoted as λ.

[0154] The thickness of the high sound velocity layer may be greater than or equal to 0.5λ; the thickness of the piezoelectric thin film 2 may range from 0.1λ to 2λ; the thickness of the bottom electrode 301 may range from 0.005λ to 0.5λ; the thickness of the interdigital transducer 4 may range from 0.005λ to 0.5λ. In this way, other performance of the acoustic wave device can be ensured while avoiding the excitation of the bulk acoustic wave mode and the resulting spurious response and bulk acoustic wave energy leakage.

[0155] The embodiment of the present application further provides a communication device, including the above acoustic wave resonator; the communication device includes at least one of a filter, a duplexer, and a multiplexer.

[0156] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An acoustic wave resonator, characterized in that: It includes a supporting substrate, and a conductive layer, a piezoelectric film and an interdigital transducer located on the supporting substrate; The interdigital transducer is at least partially disposed on the piezoelectric film; The conductive layer at least includes a bottom electrode; the piezoelectric film is at least partially disposed on the bottom electrode; The length of the bottom electrode along the first direction does not exceed the length of the aperture region of the IDT along the first direction, and the bottom electrode does not contact the IDT; the aperture region is the region where the electrode fingers of the IDT overlap; The first direction is the length direction of the electrode fingers of the IDT; The target mode of the acoustic wave resonator is an acoustic wave mode excited under the action of a longitudinal electric field, the product of the spacing between the electrode fingers of the interdigital transducer and the resonant frequency of the acoustic wave resonator is less than the slow shear wave sound velocity of the supporting substrate; the spacing between the electrode fingers of the interdigital transducer is the distance between the centers of adjacent electrode fingers on the same bus bar of the interdigital transducer; The bus bar of the interdigital transducer is in contact with the top of the supporting substrate, and the electrode fingers of the interdigital transducer are at least partially located on the piezoelectric film, and the conductive layer also includes a plurality of conductive areas, and there is a preset gap between the conductive area and the bottom electrode; the preset gap is located in the air gap area or in the air gap area and the bus bar area; the air gap area is the area between the free end of the electrode finger and the opposite bus bar.

2. The acoustic wave resonator according to claim 1, characterized in that The interdigital transducer comprises a first bus bar, a second bus bar, a plurality of first electrode fingers and a plurality of second electrode fingers; The first bus bar is provided with a plurality of first electrode fingers spaced apart by a first preset distance; The second bus bar is provided with a plurality of second electrode fingers spaced apart by a second preset distance; The plurality of first electrode fingers and the plurality of second electrode fingers are arranged alternately along a second direction; the second direction is perpendicular to the first direction; The aperture region is a region where a plurality of the first electrode fingers and a plurality of the second electrode fingers overlap.

3. The acoustic wave resonator according to claim 2, characterized in that The aperture region of the interdigital transducer is located on the piezoelectric film; The length of the bottom electrode located below the aperture region along the first direction does not exceed the length of the corresponding piezoelectric film along the first direction; There is a gap of a third preset distance between both sides of the bottom electrode and the adjacent IDT region.

4. The acoustic wave resonator according to claim 2, characterized in that The first bus bar and the second bus bar are directly disposed on top of the support substrate; There is a fourth preset distance between the side surface of the piezoelectric film close to the aperture area and the adjacent bus bar.

5. The acoustic wave resonator according to claim 4, characterized in that Ends of the first electrode fingers and / or the second electrode fingers are aligned with or extend beyond a side surface of the piezoelectric film that is close to the aperture region.

6. The acoustic wave resonator according to claim 3, characterized in that The piezoelectric film is provided with an etched through hole; Both sides of the bottom electrode are connected to the etched through hole with a gap of a third preset distance from the adjacent IDT region.

7. The acoustic wave resonator according to claim 3, characterized in that The conductive layer further includes a first region and a second region; The first bus bar is located on the first area; The second bus bar is located on the second area; There are gaps of a fifth preset distance between adjacent regions among the first region, the bottom electrode, and the second region.

8. The acoustic wave resonator according to claim 1, characterized in that The interdigital transducer also includes a pseudo-finger electrode; The dummy electrode is located outside the aperture region.

9. The acoustic wave resonator according to claim 1, characterized in that Also includes a reflective grid; The reflection grating is located on the side of the interdigital transducer.

10. The acoustic wave resonator according to claim 1, characterized in that Also includes a load piece; The load element is located on the free end of the electrode finger of the interdigital transducer; The thickness of the load element is 0.001 to 0.5 times the pitch between the electrode fingers of the IDT.

11. The acoustic wave resonator according to claim 1, characterized in that The support substrate comprises a stacked support layer and a high acoustic velocity layer; The material of the high acoustic velocity layer is any one of silicon carbide, diamond, diamond-like carbon, aluminum oxide, aluminum nitride, boron nitride, boron carbide and silicon nitride of different crystal forms and different cuts; The material of the support layer includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

12. The acoustic wave resonator according to claim 1, characterized in that The material of the bottom electrode is one or more combinations of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

13. The acoustic wave resonator according to claim 1, characterized in that The material of the piezoelectric film is one or a combination of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate or lead magnesium niobate-lead titanate.

14. The acoustic wave resonator according to claim 1, characterized in that The support substrate is a combination of one or more of silicon carbide, diamond, diamond-like carbon, silicon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride in different crystal forms and different cut shapes.

15. The acoustic wave resonator according to claim 11, characterized in that The thickness of the high acoustic velocity layer is greater than or equal to 0.5 times the spacing between the electrode fingers of the interdigital transducer; The thickness of the piezoelectric film is 0.1 to 2 times the spacing between the electrode fingers of the interdigital transducer; The thickness of the bottom electrode is 0.005 to 0.5 times the spacing between the electrode fingers of the interdigital transducer; The thickness of the IDT is 0.005 to 0.5 times the pitch between electrode fingers of the IDT.

16. The acoustic wave resonator according to claim 1, characterized in that The target mode is one of a zero-order longitudinal leakage surface acoustic wave, a high-order Lamb wave, a high-order horizontal shear wave and a high-order Rayleigh mode.

17. A method for preparing an acoustic wave resonator according to any one of claims 1 to 16, characterized in that: include: Providing a heterostructure; The heterostructure comprises a supporting substrate, a conductive material layer and a piezoelectric material layer arranged in sequence from bottom to top; Patterning the piezoelectric material layer to form the piezoelectric film, wherein the piezoelectric film includes an etched area; Etching the conductive material layer based on the etching area to form the conductive layer on the supporting substrate; The interdigital transducer is formed.

18. The method according to claim 17, characterized in that The method provides a heterostructure, comprising: Providing a piezoelectric crystal having the conductive material layer on its surface; Performing ion implantation from the surface of the conductive material layer into the piezoelectric crystal; providing a supporting substrate; After the support substrate and the conductive material layer are bonded, an annealing and stripping process is performed to obtain the heterostructure.

19. A communication device, characterized in that: comprising an acoustic wave resonator as claimed in any one of claims 1 to 16; The communication device includes at least one of a filter, a duplexer and a multiplexer.

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