Surface acoustic wave resonators, filters, and electronic devices

Abstract

The present application discloses a surface acoustic wave resonator, a filter and an electronic device, which relate to the technical field of resonators. The surface acoustic wave resonator includes a substrate assembly and an interdigital transducer. The substrate assembly includes a first piezoelectric layer and a non-piezoelectric layer. The non-piezoelectric layer is located on the periphery of the first piezoelectric layer. The interdigital transducer and the substrate assembly are stacked along a first direction. The interdigital transducer has a first excitation segment and a first reflection segment. The first excitation segment is opposite to the first piezoelectric layer in the first direction, and the first reflection segment is opposite to the non-piezoelectric layer in the first direction. The surface acoustic wave can be reflected by the first reflection segment to the first excitation segment.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of resonator technology, and in particular to a surface acoustic wave resonator, a filter, and an electronic device. Background Art

[0002] With the advancement of communication technology, the demand for resonators in electronic devices such as smartphones will increase significantly. Among these, surface acoustic wave (SAW) resonators are widely used. SAW resonators utilize the piezoelectric effect to achieve electrical-acoustic-electrical transduction, offering advantages such as a compact structure. Furthermore, by connecting SAW resonators in series and parallel, they can create RF filters with low insertion loss and a high squareness factor.

[0003] In a surface acoustic wave resonator, while exciting the main mode, it also generates unnecessary transverse modes. The existence of transverse modes or other spurious modes will produce spurious responses, increase the insertion loss of the surface acoustic wave resonator, reduce the quality factor (also called Q factor), and may affect the flatness of the filter band, that is, reduce the working performance of the filter. Summary of the Invention

[0004] The present application provides a surface acoustic wave resonator, a filter and an electronic device, which can suppress the generation of transverse modes and improve the working performance of the filter.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] In the first aspect, the present application provides a surface acoustic wave resonator, including a substrate assembly and an interdigital transducer, the substrate assembly including a first piezoelectric layer and a non-piezoelectric layer, the non-piezoelectric layer being located on the periphery of the first piezoelectric layer, the interdigital transducer and the substrate assembly being stacked along a first direction, the interdigital transducer having a first excitation segment and a first reflection segment, the first excitation segment being opposite to the first piezoelectric layer in the first direction, the first reflection segment being opposite to the non-piezoelectric layer in the first direction, and the surface acoustic wave can be reflected by the first reflection segment to the first excitation segment.

[0007] In the surface acoustic wave resonator of the embodiment of the present application, the surface acoustic waves excited by the region where the first excitation segment resides are largely reflected back to the region where the first excitation segment resides, and are not transmitted to other regions. Furthermore, the region where the first reflection segment resides does not itself excite surface acoustic waves, nor does it transmit to other regions. This prevents the first reflection segment from generating surface acoustic waves itself and causing transverse mode clutter. Furthermore, the first reflection segment can reflect surface acoustic waves transmitted from the first excitation segment, effectively suppressing the generation of transverse mode clutter and achieving the effect of primarily exciting the transverse mode.

[0008] In a possible implementation of the first aspect, an interdigital transducer includes a first bus bar, a second bus bar, and a plurality of first interdigital electrodes and a plurality of second interdigital electrodes. The first bus bar and the second bus bar are both attached to a predetermined surface and spaced apart along a second direction. The plurality of first interdigital electrodes and the plurality of second interdigital electrodes are both attached to the predetermined surface, and the first and second interdigital electrodes are alternately spaced apart and arranged in parallel along a third direction. Thus, a second interdigital electrode is disposed between two adjacent first interdigital electrodes, and a first interdigital electrode is disposed between two adjacent second interdigital electrodes. One end of a first interdigital electrode is connected to the first bus bar, and the other end is spaced apart from the second bus bar. One end of a second interdigital electrode is connected to the second bus bar, and the other end is spaced apart from the first bus bar. In other words, each first interdigital electrode and each second interdigital electrode is located between the first and second bus bars, with the first interdigital electrode connected to the first bus bar and the second interdigital electrode connected to the second bus bar. The first, second, and third directions are perpendicular to each other. The first excitation segment and the first reflection segment may both be located on the first interdigital electrode. The first excitation segment and the first reflection segment may also both be located on the second interdigital electrode, which is not a limitation in this application. For example, the first excitation segment and the first reflection segment may be located on the first interdigital electrode, and the second excitation segment and the second reflection segment may be located on the second interdigital electrode, thereby achieving a superposition effect of the excitation segment and the reflection segment.

[0009] In a possible implementation of the first aspect, the surface acoustic wave resonator has a first sound velocity zone and a third sound velocity zone, the third sound velocity zone is located on one side of the first sound velocity zone in the second direction, the first piezoelectric layer and the first excitation segment are located in the first sound velocity zone, that is, the first piezoelectric layer and the first excitation segment are stacked in the first direction to form the first sound velocity zone, and the first transition segment and the non-piezoelectric layer are located in the third sound velocity zone, that is, the first transition segment and the non-piezoelectric layer are stacked in the first direction to form the third sound velocity zone.

[0010] The first sound velocity zone forms the main excitation area of ​​the surface acoustic wave, that is, the first sound velocity zone in the embodiment of the present application has the same function as the first sound velocity zone in the above text. The surface acoustic wave excited by the first sound velocity zone can be transmitted outward, that is, to one side of the third sound velocity zone, and is reflected by the third sound velocity zone. That is, the third sound velocity zone in the embodiment of the present application can be the same as the third sound velocity zone in the above text of the figure.

[0011] In this way, by introducing the non-piezoelectric layer in the third sound velocity zone, no acoustic interference will occur between the first sound velocity zone and the third sound velocity zone. That is, the surface acoustic waves excited in the first sound velocity zone will not be transmitted to the third sound velocity zone, and the third sound velocity zone itself will not excite surface acoustic waves, so that there are fewer surface acoustic waves oscillating in the third sound velocity zone, and most of the surface acoustic waves excited in the first sound velocity zone are still concentrated in the first sound velocity zone, so that the surface acoustic wave resonator of the embodiment of the present application forms a main mode excitation, reducing the generation of transverse mode noise.

[0012] In one possible implementation of the first aspect, the acoustic velocity of the surface acoustic wave in the first reflection section is not equal to the acoustic velocity in the first excitation section. That is, the acoustic velocity of the surface acoustic wave in the first acoustic velocity region is less than or greater than the acoustic velocity of the surface acoustic wave in the third acoustic velocity region, and at the same time, the third acoustic velocity region does not excite surface acoustic waves. This prevents interference between the third acoustic velocity region and the first acoustic velocity region. Specifically, this results in discontinuous surface acoustic wave transmission between the first and third acoustic velocity regions. The third acoustic velocity region forms a reflective structure for the first acoustic velocity region, effectively reflecting the surface acoustic wave in the first acoustic velocity region.

[0013] In one possible implementation of the first aspect, the thickness of the first reflection segment is greater than or less than the thickness of the first excitation segment. The sound velocities of different sound velocity zones depend on the material properties, materiality, and thickness of each layer in the region. In some embodiments, by setting different thicknesses in the first direction for the first reflection segment and the first excitation segment, the sound velocities of the first sound velocity zone and the third sound velocity zone can be different, resulting in simple and low-cost manufacturing.

[0014] In a possible implementation of the first aspect, when the thickness of the first reflection segment in the first direction is greater than the thickness of the first excitation segment in the first direction, the sound velocity of the first sound velocity zone is greater than the sound velocity of the second sound velocity zone. Similarly, when the thickness of the first reflection segment in the first direction is less than the thickness of the first excitation segment in the first direction, the sound velocity of the first sound velocity zone is less than the sound velocity of the second sound velocity zone. In an embodiment of the present application, under the premise that the first reflection segment and the non-piezoelectric layer are directly opposite and do not excite surface acoustic waves, as long as the sound velocity of the surface acoustic wave in the first reflection segment is not equal to the sound velocity in the first excitation segment, the third sound velocity zone can reflect the surface acoustic wave transmitted from the first sound velocity zone.

[0015] In one possible implementation of the first aspect, the IDT further includes a first transition section, the first transition section being located between the first excitation section and the first reflection section, and the first transition section being directly opposite the non-piezoelectric layer in the first direction. In this case, the first excitation section, the first transition section, and the first reflection section may be sequentially arranged on the first interdigital electrode along the second direction. Furthermore, surface acoustic waves are not excited in the regions where the first reflection section and the first transition section are located.

[0016] The surface acoustic wave excited by the first excitation segment can propagate to the first transition segment, where it is then reflected by the first reflection segment back to the first transition segment before propagating to the first excitation segment, completing a round trip of the surface acoustic wave. At this point, both the first transition segment and the first reflection segment are directly opposite the non-piezoelectric layer. When fabricating the surface acoustic wave resonator, it is sufficient to ensure that the first excitation segment and the first piezoelectric layer are directly opposite each other. This reduces the fabrication precision of the boundary of the non-piezoelectric layer and eliminates the need to ensure that the orthographic projection of the first reflection segment on the non-piezoelectric layer completely overlaps with the non-piezoelectric layer, thereby simplifying the fabrication process.

[0017] Furthermore, by providing the first transition section, the propagation path of the surface acoustic wave in the first excitation section is extended, and the generation of transverse mode clutter can be effectively suppressed.

[0018] In one possible implementation of the first aspect, the surface acoustic wave resonator further includes a second sound velocity zone, the second sound velocity zone being located on one side of the first sound velocity zone in the second direction, and a third sound velocity zone being located on a side of the second sound velocity zone facing away from the first sound velocity zone in the second direction, thereby forming the first sound velocity zone, the second sound velocity zone, and the third sound velocity zone arranged sequentially along the second direction. The first transition section and a portion of the non-piezoelectric layer are located in the second sound velocity zone, and the first reflection section and another portion of the non-piezoelectric layer are located in the third sound velocity zone. This enables reciprocating transmission of surface acoustic waves between the first sound velocity zone and the second sound velocity zone.

[0019] In one possible implementation of the first aspect, the acoustic velocity of the surface acoustic wave in the first excitation segment is equal to the acoustic velocity in the first transition segment. Thus, continuous transmission of the surface acoustic wave occurs between the first and second acoustic velocity zones. For example, to achieve the same acoustic velocity of the surface acoustic wave in the first and second acoustic velocity zones, the thickness of the first excitation segment in the first direction can be equal to the thickness of the first transition segment in the first direction, thereby achieving continuous reciprocating transmission of the surface acoustic wave between the first and second acoustic velocity zones.

[0020] In one possible implementation of the first aspect, the non-piezoelectric layer includes a first portion and a second portion, the first portion being opposite the first transition section in a first direction, and the second portion being opposite the first reflective section in the first direction. The first portion forms an inner boundary of the second portion, and the presence of the second portion reduces the difficulty of preparing the non-piezoelectric layer in the second portion. Furthermore, since both the second portion and the first portion are non-piezoelectric layers, surface acoustic waves are not excited in the second and third sound velocity regions.

[0021] In one possible implementation of the first aspect, the first portion and the second portion have the same thickness in the first direction, and the first portion and the second portion have the same acoustic impedance. Thus, the non-piezoelectric layer can be formed using the same material in a single process, thereby simplifying the substrate assembly manufacturing process.

[0022] In one possible implementation of the first aspect, two second sound velocity zones and two third sound velocity zones are each included. The two second sound velocity zones are located on opposite sides of the first sound velocity zone in the second direction, and the two third sound velocity zones are located on opposite sides of the second sound velocity zone in the second direction. Each second sound velocity zone includes a first transition section and a non-piezoelectric layer, and each third sound velocity zone includes a first reflection section and a non-piezoelectric layer. The second direction is perpendicular to the first direction. In this way, the third sound velocity zones can reflect surface acoustic waves from opposite sides of the first sound velocity zone in the second direction, thereby enhancing the excitation effect of the main mode.

[0023] In one possible implementation of the first aspect, the first piezoelectric layer and the non-piezoelectric layer are made of the same material. For example, the piezoelectric layer and the non-piezoelectric layer can both be made of lithium niobate or lithium tantalate. Different processes are used to form the first piezoelectric layer with piezoelectric properties and a specific crystal orientation, and the isotropic non-piezoelectric layer without piezoelectric properties or with a different crystal orientation and piezoelectric properties from the first piezoelectric layer. In this way, the thickness and material between the first sound velocity zone and the second sound velocity zone are the same, ensuring the same sound speed in the first and second sound velocity zones, allowing surface acoustic waves to propagate back and forth between the first and second sound velocity zones.

[0024] In one possible implementation of the first aspect, the first piezoelectric layer and the non-piezoelectric layer have the same thickness in the first direction, and the first piezoelectric layer and the non-piezoelectric layer have the same acoustic impedance. This ensures that the material properties of the first piezoelectric layer and the non-piezoelectric layer are the same, and also ensures that the sound speeds in the first sound velocity zone and the second sound velocity zone are the same.

[0025] In one possible implementation of the first aspect, in the first direction, the thickness of the non-piezoelectric layer is equal to the thickness of the first piezoelectric layer. That is, in the first direction, the non-piezoelectric layer is not disposed at a location where the first piezoelectric layer is disposed, and the first piezoelectric layer is not disposed at a location where the non-piezoelectric layer is disposed. The first piezoelectric layer and the non-piezoelectric layer are not stacked in the first direction. In this way, when preparing the substrate assembly, it is only necessary to drill a hole in the piezoelectric material layer and plate the non-piezoelectric material layer, without having to consider the drilling depth. This simplifies the preparation of the surface acoustic wave resonator and reduces the process precision requirements, thereby reducing costs and improving economic benefits.

[0026] In a possible implementation of the first aspect, the substrate assembly further includes a second piezoelectric layer, and the second piezoelectric layer is located outside the non-piezoelectric layer, thereby avoiding a large amount of waste of piezoelectric material.

[0027] In a possible implementation of the first aspect, the substrate assembly further includes a third piezoelectric layer, the third piezoelectric layer is located on the periphery of the first piezoelectric layer, the non-piezoelectric layer and at least part of the third piezoelectric layer are stacked along the first direction, and the non-piezoelectric layer is located between the interdigital transducer and the third piezoelectric layer. In this way, a superposition method in which the first reflection section, the non-piezoelectric layer and the third piezoelectric layer are arranged in sequence is formed in the third sound velocity zone to ensure that the first reflection section does not excite surface acoustic waves on the piezoelectric substrate. In this way, when manufacturing the substrate assembly, when the third piezoelectric layer does not extend to the boundary of the piezoelectric substrate in the second direction, less waste of the piezoelectric material layer is achieved, thereby reducing the manufacturing cost. When the third piezoelectric layer extends to the boundary of the piezoelectric substrate in the second direction, the difficulty and accuracy of manufacturing the substrate assembly can be reduced.

[0028] In one possible implementation of the first aspect, the non-piezoelectric layer has a thickness of h1 in the first direction, the third piezoelectric layer stacked with the non-piezoelectric layer has a thickness of h2 in the first direction, and h1 / (h1+h2) is greater than or equal to 20%. This ensures that the thickness of the non-piezoelectric layer is within an appropriate range to ensure that the third sound velocity region does not effectively excite surface acoustic waves.

[0029] In one possible implementation of the first aspect, the surface acoustic wave resonator further includes a base layer, the substrate assembly is disposed on the base layer, and the IDT is located on a side of the substrate assembly facing away from the base layer. The base layer is disposed at the bottom and serves as a substrate for the other layers, carrying and supporting the other layered structures (including but not limited to the functional layer, IDT, and substrate assembly).

[0030] In one possible implementation of the first aspect, the surface acoustic wave resonator further includes a functional layer, which is disposed on a side of the interdigital transducer facing away from the substrate assembly. The functional layer can provide different functions. For example, the functional layer can provide a temperature compensation function for temperature compensation of the surface acoustic wave resonator, in which case the surface acoustic wave resonator is a temperature-compensated surface acoustic wave device. The functional layer can also provide a passivation function for protection, in which case the surface acoustic wave resonator is a thin-film surface acoustic wave device.

[0031] In a second aspect, the present application provides a filter comprising a surface acoustic wave resonator according to any of the aforementioned embodiments. The surface acoustic wave resonator primarily operates by utilizing the piezoelectric properties of piezoelectricity, using input and output transducers to convert radio wave input signals into mechanical energy. After processing, the mechanical energy is then converted into an electrical signal, thereby filtering out unnecessary signals and noise and improving reception quality. The filter utilizes the surface acoustic wave resonator to effectively filter out specific frequencies within a signal, or frequencies outside of those frequencies, thereby obtaining a signal at a specific frequency, or eliminating a signal after a specific frequency has been eliminated, thereby improving the performance of the electronic device.

[0032] In a third aspect, the present application provides an electronic device comprising the surface acoustic wave resonator of any of the above embodiments.

[0033] In a fourth aspect, the present application provides an electronic device comprising the filter of any of the above embodiments.

[0034] Among them, the technical effects brought about by the second to fourth aspects can also refer to the technical effects brought about by the different design methods in the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the structure of an electronic device provided in some embodiments of the present application;

[0036] Figure 2 A schematic cross-sectional view of a surface acoustic wave resonator provided in some embodiments of the present application;

[0037] Figure 3 for Figure 2 Schematic diagram of the planar structure of the interdigital transducer of the surface wave resonator shown;

[0038] Figure 4 for Figure 3 Phase velocity (sound speed)-position diagram of the surface acoustic wave resonator corresponding to different sound speed regions;

[0039] Figure 5 Schematic diagram of the cross-sectional structure of a surface acoustic wave resonator provided in some other embodiments of the present application;

[0040] Figure 6 for Figure 5 Schematic diagram of the planar structure of the interdigital transducer of the surface acoustic wave resonator shown;

[0041] Figure 7 for Figure 6 Phase velocity (sound speed)-position diagram of the surface acoustic wave resonator corresponding to different sound speed regions;

[0042] Figure 8 A schematic structural diagram of a surface acoustic wave resonator provided in some embodiments of the present application;

[0043] Figure 9 Schematic diagram of the structure of the surface acoustic wave resonator provided in other embodiments of the present application;

[0044] Figure 10 Schematic diagram of the cross-sectional structure of a surface acoustic wave resonator provided in some other embodiments of the present application;

[0045] Figure 11 for Figure 5 The surface acoustic wave resonator shown is Figure 10 Comparison of the admittance curves of the surface acoustic wave resonators shown;

[0046] Figure 12 for Figure 10 Schematic diagram of the planar structure of the interdigital transducer of the surface acoustic wave resonator shown;

[0047] Figure 13 for Figure 10 A schematic cross-sectional structure diagram of a surface acoustic wave resonator is shown;

[0048] Figure 14 Schematic diagram of the cross-sectional structure of a surface acoustic wave resonator provided in some other embodiments of the present application;

[0049] Figure 15 for Figure 10Phase velocity (sound speed)-position diagram of the surface acoustic wave resonator corresponding to different sound speed regions;

[0050] Figure 16 Schematic diagram of the cross-sectional structure of a surface acoustic wave resonator provided in some other embodiments of the present application;

[0051] Figure 17 for Figure 10 Schematic diagram of the preparation process of the substrate assembly of the surface acoustic wave resonator shown;

[0052] Figure 18 Schematic diagram of the cross-sectional structure of a surface acoustic wave resonator provided in some other embodiments of the present application;

[0053] Figure 19 for Figure 18 Schematic diagram of the preparation process of the substrate assembly of the surface acoustic wave resonator shown;

[0054] Figure 20 Schematic diagram of the cross-sectional structure of a surface acoustic wave resonator provided in some other embodiments of the present application;

[0055] Figure 21 Schematic diagram of the cross-sectional structure of the surface acoustic wave resonator provided in some other embodiments of the present application.

[0056] Reference numerals:

[0057] 1000, electronic device; 100a, filter; 100, surface acoustic wave resonator; A1, first sound velocity region; A2, second sound velocity region; A3, third sound velocity region; A4, fourth sound velocity region; A5, fifth sound velocity region;

[0058] 10. Piezoelectric substrate; 11. Preset surface; 20. IDT; 21. First bus bar; 22. Second bus bar; 23. First interdigital electrode; 24. Second interdigital electrode; 20a. First excitation segment; 20b. First transition segment; 20c. First reflection segment; 30. Base layer; 40. Functional layer; 50. Substrate assembly; 51. First piezoelectric layer; 52. Non-piezoelectric layer; 521. First portion; 522. Second portion; 53. Second piezoelectric layer; 54. Third piezoelectric layer;

[0059] 60. Piezoelectric material layer; 61. Through hole; 62. Empty groove; 70. Non-piezoelectric material layer; L1. First direction; L2. Second direction; L3. Third direction. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0061] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being more preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0062] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0063] In the description of the embodiments of this application, "and / or" is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0064] In the embodiments of the present application, directional terms such as "outside" may be defined including but not limited to the orientation relative to the schematic placement of the components in the drawings. It should be understood that these directional terms may be relative concepts. They are used for relative description and clarification, and may change accordingly according to changes in the orientation of the components in the drawings.

[0065] In the description of the embodiments of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, "connected" can mean detachably connected or non-detachably connected; directly connected or indirectly connected through an intermediary. "Fixedly connected" means connected so that the relative positional relationship remains unchanged after connection.

[0066] In the description of the embodiments of the present application, the terms "perpendicular" and "parallel" include the described conditions and conditions similar to the described conditions, and the range of the similar conditions is within an acceptable deviation range, where the acceptable deviation range is determined by a person of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the specific quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximately parallelism, where the acceptable deviation range for approximately parallelism can be, for example, within 5°, 8°, or 10°; "perpendicular" includes absolute perpendicularity and approximately perpendicularity, where the acceptable deviation range for approximately perpendicularity can also be, for example, within 5°, 8°, or 10°.

[0067] Quality factor (Q): This represents the energy efficiency of a device, i.e., the ratio of the total energy received by the device to the energy dissipated during one vibration cycle. In filter design, the quality factor (Q) of the resonator that makes up the filter is an important parameter.

[0068] The present application provides an electronic device, including but not limited to a radio frequency front end, a filter amplifier module, a base station wireless communication system, and other products. The electronic device may also include a mobile phone, a tablet computer (pad), a smart wearable product (e.g., a smart watch, a smart bracelet), a virtual reality (VR) device, an augmented reality (AR) device, a drone, and other terminal devices with communication capabilities. The present application does not impose any particular restrictions on the specific form of the electronic device.

[0069] See also Figure 1 , Figure 1 A structural diagram of an electronic device 1000 is provided for some embodiments of the present application. In an electronic device 1000 such as the above-mentioned one, the electronic device 1000 may include a filter 100a. The filter 100a can 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 1000.

[0070] Specifically, in some embodiments, electronic device 1000 communicates via a signal transmission and reception system. This system may include a receiver, a transmitter, an antenna, and a baseband chip. The antenna is electrically connected to the receiver and transmitter, respectively, to enable signal reception and transmission. The receiver and transmitter are also electrically connected to the baseband chip, respectively, to perform signal processing functions such as decoding, modulation, and demodulation.

[0071] The receiver receives the signal from the antenna and passes the processed signal to the baseband chip. The baseband chip decodes and demodulates the received signal to restore the original information data, and encodes and modulates the information data to be sent to generate an electrical signal suitable for the transmitter to transmit. The transmitter converts the information data to be sent into electrical signals and transmits these electrical signals through the antenna.

[0072] In some embodiments, filters 100a can be provided in both the receiver and the transmitter. Filters 100a can filter out unwanted or undesirable frequencies or noise. For example, the receiver can include filter 100a and a low-noise amplifier, and filter 100a can filter out noise from the low-noise amplifier. The transmitter can include filter 100a and a power amplifier, and filter 100a can effectively filter out specific frequencies amplified by the power amplifier or frequencies outside of those frequencies.

[0073] It is understood that the above description only introduces part of the structure and function of the signal transmission and reception system of the electronic device 1000 and does not limit the electronic device 1000. In other embodiments, the signal transmission and reception system of the electronic device 1000 may further include other electronic components, which is not limited in this application.

[0074] The filter 100a may include multiple resonators connected in series, or multiple resonators connected in parallel, or a combination of series and parallel resonators. In addition, the filter 100a involved in the present application may be a SAW ladder filter, a SAW mesh filter, or a combination of these structures.

[0075] In some embodiments, at least one of the multiple resonators included in filter 100a may be a surface acoustic wave (SAW) resonator 100. The primary operating principle of SAW resonator 100 is to utilize the piezoelectric properties of piezoelectricity, using input and output transducers to convert radio wave input signals into mechanical energy. After processing, the mechanical energy is then converted back into an electrical signal, thereby filtering out unnecessary signals and noise, thereby improving reception quality.

[0076] See also Figure 2 , Figure 2 The schematic cross-sectional structure of a surface acoustic wave resonator 100 provided in some embodiments of the present application includes a piezoelectric substrate 10 and an IDT 20. The piezoelectric substrate 10 is plate-shaped, and the IDT 20 and the piezoelectric substrate 10 are stacked along a first direction L1. That is, the IDT 20 is disposed on a predetermined surface 11 on one side of the piezoelectric substrate 10 in the thickness direction. Upon receiving an electrical signal, the IDT 20 drives the piezoelectric substrate 10 to vibrate, generating a surface acoustic wave. The surface acoustic wave is transmitted along the predetermined surface 11, thereby converting the electrical signal into a mechanical vibration signal.

[0077] This embodiment does not impose any restrictions on the material of the piezoelectric substrate 10, as long as the piezoelectric substrate 10 can vibrate and generate surface acoustic waves when driven by the interdigital transducer 20. Exemplary materials for the piezoelectric substrate 10 include: piezoelectric crystals with specific crystal orientations, such as lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and quartz; piezoelectric films, such as aluminum nitride (AlN) and scandium-doped aluminum nitride (AlScN); and piezoelectric ceramics, such as lead metaniobate (PbNb2O6) and lead zirconate titanate (PZT).

[0078] In some embodiments, please refer to Figure 2 The SAW resonator 100 further includes a base layer 30 and a functional layer 40. The base layer 30 is disposed on a side of the piezoelectric substrate 10 facing away from the IDT 20, and the functional layer 40 is disposed on a side of the IDT 20 facing away from the piezoelectric substrate 10. That is, the SAW resonator 100 forms a structural arrangement in which the functional layer 40, the IDT 20, the piezoelectric substrate 10, and the base layer 30 are stacked in sequence along the first direction L1.

[0079] The base layer 30 is disposed at the bottom and serves as a substrate for the other layers, carrying and supporting the other layered structures (including but not limited to the functional layer 40, the interdigital transducer 20, and the piezoelectric substrate 10). The functional layer 40 can provide different functions. For example, the functional layer 40 can provide a temperature compensation function to compensate the temperature of the surface acoustic wave resonator 100, in which case the surface acoustic wave resonator 100 is a temperature compensation surface acoustic wave (TC-SAW) device. The functional layer 40 can also provide a passivation function to provide protection, in which case the surface acoustic wave resonator 100 is a thin film surface acoustic wave (TF-SAW) device.

[0080] In other embodiments, the surface acoustic wave device may also form a standard surface acoustic wave (STD-SAW) device, which is not limited in this application.

[0081] The IDT 20 drives the piezoelectric substrate 10 to vibrate under the action of the electrical signal. Figure 2 and Figure 3 , Figure 3 for Figure 2The schematic diagram of the partial planar structure of the interdigital transducer 20 of the surface acoustic wave resonator 100 is shown. The interdigital transducer 20 includes a first bus bar 21, a second bus bar 22, and a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24. The first bus bar 21 and the second bus bar 22 are both attached to the predetermined surface 11 and spaced apart along the second direction L2. The plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 are both attached to the predetermined surface 11, and the first interdigital electrodes 23 and the second interdigital electrodes 24 are alternately spaced and arranged in parallel along the third direction L3. Thus, a second interdigital electrode 24 is disposed between two adjacent first interdigital electrodes 23, and a first interdigital electrode 23 is disposed between two adjacent second interdigital electrodes 24. One end of the first interdigital electrode 23 is connected to the first bus bar 21, and the other end is spaced apart from the second bus bar 22. One end of the second interdigital electrode 24 is connected to the second bus bar 22, and the other end is spaced apart from the first bus bar 21. That is, each first interdigital electrode 23 and each second interdigital electrode 24 is located between the first bus bar 21 and the second bus bar 22, with the first interdigital electrode 23 connected to the first bus bar 21 and the second interdigital electrode 24 connected to the second bus bar 22. The first direction L1, the second direction L2, and the third direction L3 are perpendicular to each other.

[0082] During operation, power can be supplied to the first interdigital electrodes 23 via the first bus bar 21, and to the second interdigital electrodes 24 via the second bus bar 22, thereby causing the piezoelectric substrate 10 to vibrate to generate surface acoustic waves. The surface acoustic waves propagate in a direction parallel to the predetermined surface 11 near the predetermined surface 11. In some embodiments, the surface acoustic waves can propagate along the third direction L3. In other embodiments, the surface acoustic waves can also propagate in a manner in which most of the surface acoustic waves propagate along the third direction L3, with a small portion propagating in other directions.

[0083] It is worth noting that this embodiment does not limit the structure of the IDT 20 . The IDT 20 may also have other structures as long as it can drive the piezoelectric substrate 10 to vibrate under the action of an electrical signal and thereby form a surface acoustic wave.

[0084] In some embodiments, please refer to Figure 2 and Figure 3 The surface acoustic wave resonator 100 includes a first acoustic velocity region A1, a fourth acoustic velocity region A4, and a fifth acoustic velocity region A5. The first acoustic velocity region A1 is the region where the first interdigital electrodes 23, the second interdigital electrodes 24, and the piezoelectric substrate 10 are stacked relative to each other. The fourth acoustic velocity region A4 is located on both sides of the first acoustic velocity region A1 in the second direction L2. The fourth acoustic velocity region A4 is formed only where the first interdigital electrodes 23 or the second interdigital electrodes 24 and the piezoelectric substrate 10 are stacked relative to each other. The fifth acoustic velocity region A5 is formed where the first bus bar 21, the second bus bar 22, and the piezoelectric substrate 10 are stacked relative to each other. Please refer to the reference to FIG. Figure 4, Figure 4 for Figure 3 The phase velocity (sound speed)-position diagram of the surface acoustic wave resonator 100 corresponding to different sound speed zones is shown. The first sound speed zone A1 forms the main excitation area of ​​the surface acoustic wave. The sound speed of the first sound speed zone A1 is a1, the sound speed of the fourth sound speed zone A4 is a4, and the sound speed of the fifth sound speed zone A5 is a5.

[0085] In some embodiments, surface acoustic wave interference occurs between the first sound velocity zone A1 and the fourth sound velocity zone A4. Specifically, surface acoustic waves can be easily transmitted from the low sound velocity zone (a1) to the high sound velocity zone (a4). At this time, a large number of surface acoustic waves excited by the first sound velocity zone A1 are transmitted to the fourth sound velocity zone A4.

[0086] There is no surface acoustic wave interference between the fourth sound velocity zone A4 and the fifth sound velocity zone A5. Specifically, it is difficult for surface acoustic waves to enter the low sound velocity zone (a5) from the high sound velocity zone (a4). Most surface acoustic waves in the fourth sound velocity zone A4 are reflected back to the fourth sound velocity zone A4 by the fifth sound velocity zone A5, and fewer surface acoustic waves enter the fourth sound velocity zone A4. In this way, more surface acoustic waves in the first sound velocity zone A1 enter the fourth sound velocity zone A4, while less surface acoustic waves enter the fourth sound velocity zone A4. That is, this part of the surface acoustic waves is confined to oscillate in the fourth sound velocity zone A4. The total amount of surface acoustic waves in the fourth sound velocity zone A4 / the total amount of surface acoustic waves in the first sound velocity zone A1 is larger. In this way, Figures 2 to 4 The surface acoustic wave resonator 100 of the illustrated embodiment exhibits a high level of transverse mode spurious waves.

[0087] To reduce the transverse mode noise of the SAW resonator 100, refer to Figure 5 , Figure 5 Schematic diagram of the cross-sectional structure of the surface acoustic wave resonator 100 provided in some other embodiments of the present application, Figure 6 for Figure 5 The schematic plan view of the interdigital transducer 20 of the surface acoustic wave resonator 100 is shown in FIG. Figure 3 One difference between the illustrated embodiment and the present invention is that the surface acoustic wave resonator 100 further includes a third sound velocity region A3 , which is located between the first sound velocity region A1 and the fourth sound velocity region A4 .

[0088] The third sound velocity region A3 is formed by the local thickening of the first interdigital electrode 23 and / or the second interdigital electrode 24. Figure 6 As an example, the first interdigital electrode 23 shown in FIG. 1 includes a first excitation segment 20 a located in the first sound velocity zone A1 and a first reflection segment 20 c located in the third sound velocity zone A3. The thickness of the first reflection segment 20 c in the first direction L1 is greater than the thickness of the first excitation segment 20 a in the first direction L1 (see FIG. Figure 5In this way, the third sound velocity area A3 forms a reflection structure of the first sound velocity area A1.

[0089] Please refer to Figure 5 and Figure 7 , Figure 7 for Figure 6 The phase velocity (sound velocity)-position diagram of the surface acoustic wave resonator 100 shown corresponds to different sound velocity zones. On the basis that the thickness of the first reflection section 20c in the first direction L1 is greater than the thickness of the first excitation section 20a in the first direction L1, the sound velocity of the third sound velocity zone A3 is different from the sound velocity of the first sound velocity zone A1. At this time, the sound velocity of the third sound velocity zone A3 is a3, and a3 is smaller than a1. Due to the thickening of the first reflection section 20c, the third sound velocity zone A3 and the first sound velocity zone A1 where the first excitation section 20a is located do not interfere with each other. In this way, the third sound velocity zone A3 forms a strong reflection zone, and more surface acoustic waves in the first sound velocity zone A1 are reflected back to the first sound velocity zone A1 by the third sound velocity zone A3, and fewer enter the fourth sound velocity zone A4 and the fifth sound velocity zone A5. The total amount of surface acoustic waves in the fourth sound velocity zone A4 / the total amount of surface acoustic waves in the first sound velocity zone A1 is smaller, so that Figures 5 to 7 The surface acoustic wave resonator 100 of the illustrated embodiment exhibits relatively weak transverse mode spurious waves.

[0090] However, because the first reflection section 20c of the third acoustic velocity zone A3 can itself excite the underlying piezoelectric substrate 10 to generate surface acoustic waves, the surface acoustic waves excited by the third acoustic velocity zone A3 can be transmitted to a greater extent to the fourth acoustic velocity zone A4. The surface acoustic waves in the fourth acoustic velocity zone A4 are then reflected back to the fourth acoustic velocity zone A4 by the fifth acoustic velocity zone A5. As a result, the surface acoustic wave energy in the fourth acoustic velocity zone A4 is still relatively high, that is, the surface acoustic wave resonator 100 in the embodiment of the present application still has transverse mode noise. It can be understood that the greater the width of the third acoustic velocity zone A3 in the second direction L2, the larger the surface acoustic waves it excites, and the more transverse mode noise there is.

[0091] In other embodiments, see Figure 8 , Figure 8 This is a schematic structural diagram of a surface acoustic wave resonator 100 provided in some embodiments of the present application, wherein Figure 8 (a) is a schematic diagram of the planar structure of the interdigital transducer 20 of the surface acoustic wave resonator 100. Figure 8 (b) is a schematic cross-sectional view of the surface acoustic wave resonator 100. Figure 8 (c) in Figure 8 Figure (b) shows a phase velocity (acoustic speed)-position diagram for different acoustic speed zones for a surface acoustic wave resonator. In this embodiment, a high-density material D is provided within the functional layer 40 in the third acoustic speed zone A3. This high-density material D has a greater density than the material used for the piezoelectric substrate 10, thereby reducing transverse mode noise.

[0092] See also Figure 9 , Figure 9 This is a schematic structural diagram of a surface acoustic wave resonator 100 provided in some other embodiments of the present application, wherein Figure 9 (a) is a schematic diagram of the planar structure of the interdigital transducer 20 of the surface acoustic wave resonator 100. Figure 9 (b) is a schematic cross-sectional view of the surface acoustic wave resonator 100. Figure 9 (c) in Figure 9 Figure (b) shows a phase velocity (acoustic speed)-position diagram for different acoustic speed zones for the surface acoustic wave resonator. In this embodiment, transverse mode clutter is reduced by increasing the area occupied by the first reflective segment 20c in the third acoustic speed zone A3 on the predetermined surface 11 (that is, the ratio of the orthographic projection of the first reflective segment 20c on the predetermined surface 11 to the total orthographic projection area of ​​the IDT 20 on the predetermined surface 11).

[0093] and Figures 5 to 7 The same thing as the embodiments shown is that Figure 8 and Figure 9 The third sound velocity zone A3 of the embodiment shown can generate surface acoustic waves that are transmitted to the fourth sound velocity zone A4, resulting in the surface acoustic wave energy in the fourth sound velocity zone A4 being still relatively high, and the transverse mode clutter phenomenon is still not resolved. In other embodiments, the transverse mode clutter phenomenon can be improved by covering the interdigital transducer 20 with another layer of metal structure to change the metal area, but it will still cause the same problem as above. Figures 5 to 7 Same problem.

[0094] Based on this, in order to effectively suppress the transverse mode clutter phenomenon, please refer to Figure 10 , Figure 10 Schematic diagram of the cross-sectional structure of the surface acoustic wave resonator 100 provided in some other embodiments of the present application, Figures 5 and 6 The same as the embodiment shown is that the base layer 30 and the functional layer 40 of the embodiment shown in this application are the same as those of the above embodiment. Figures 5 and 6 One difference between the illustrated embodiment and the embodiment is that the present application changes the piezoelectric substrate 10 to a different substrate assembly 50 , and through the coordination between the substrate assembly 50 and the layers of the IDT 20 , effective suppression of transverse mode clutter is achieved.

[0095] Specifically, the surface acoustic wave resonator 100 includes a substrate assembly 50 and an IDT 20 stacked along a first direction L1. One side of the substrate assembly 50 is formed with a Figure 5The piezoelectric substrate 10 shown has the same preset surface 11, and the substrate assembly 50 includes a first piezoelectric layer 51 and a non-piezoelectric layer 52. The non-piezoelectric layer 52 is located on the periphery of the first piezoelectric layer 51. At this time, the preset surface 11 is formed by the first piezoelectric layer 51 and the non-piezoelectric layer 52, and the interdigital transducer 20 is located on one side of the preset surface 11.

[0096] The IDT 20 comprises a first excitation segment 20a and a first reflection segment 20c. The first excitation segment 20a and the first piezoelectric layer 51 are aligned in a first direction L1 to excite surface acoustic waves (SAWs). The first piezoelectric layer 51 can be made of the same material as the piezoelectric substrate 10 in any of the above embodiments. The first piezoelectric layer 51 can vibrate under the excitation of the first excitation segment 20a, thereby generating SAWs. The first reflection segment 20c and the non-piezoelectric layer 52 are aligned in a first direction L1 to reflect SAWs. In other words, SAWs can be transmitted from one side of the first excitation segment 20a to the first reflection segment 20c and then reflected by the first reflection segment 20c back to the first excitation segment 20a.

[0097] It is understood that the non-piezoelectric layer 52 is located on the periphery of the first piezoelectric layer 51. The non-piezoelectric layer 52 may surround the first piezoelectric layer 51. In this case, the non-piezoelectric layer 52 is located on all sides of the first piezoelectric layer 51. Alternatively, the non-piezoelectric layer 52 may be located on both sides of the first piezoelectric layer 51 in a certain direction, for example, Figure 10 In the embodiment, the non-piezoelectric layer 52 is located on two opposite sides of the first piezoelectric layer 51 in the second direction L2, thereby effectively reflecting the surface acoustic wave transmitted to the periphery by the first excitation segment 20a.

[0098] The first excitation segment 20a is directly opposite to the first piezoelectric layer 51, which can be understood as the orthographic projection of the first excitation segment 20a on the first piezoelectric layer 51 entirely falling within the first piezoelectric layer 51. Similarly, the first reflection segment 20c is directly opposite to the non-piezoelectric layer 52, which can be understood as the orthographic projection of the first reflection segment 20c on the non-piezoelectric layer 52 entirely falling within the non-piezoelectric layer 52. Since the non-piezoelectric layer 52 does not have piezoelectric properties, that is, the non-piezoelectric layer 52 cannot be excited to generate surface acoustic waves. At this time, the first reflection segment 20c cannot excite the underlying substrate assembly 50 to generate surface acoustic waves.

[0099] In this way, the surface acoustic wave excited in the area where the first excitation segment 20a is located is largely reflected back to the area where the first excitation segment 20a is located, and will not be transmitted to other areas. At the same time, the area where the first reflection segment 20c is located will not excite the surface acoustic wave itself, nor will it be transmitted to other areas. Compared with the above Figures 5 to 7The surface acoustic wave resonator 100 of the embodiment shown avoids the situation where the first reflection section 20 c itself generates surface acoustic waves and causes the existence of transverse mode noise. At the same time, the first reflection section 20 c can also reflect the surface acoustic waves transmitted from the first excitation section 20 a, thereby effectively suppressing the generation of transverse mode noise and achieving the effect of mainly exciting the transverse mode.

[0100] See also Figure 11 , Figure 11 for Figure 5 The surface acoustic wave resonator 100 is shown with Figure 10 The following is a comparison of the admittance curves of the surface acoustic wave resonator 100. The horizontal axis of the admittance curve represents frequency (MHz), and the vertical axis represents admittance (Siemens (S)). Admittance is a measure of the response of a circuit or system to alternating current. It is the reciprocal of impedance. The high and low values ​​of the vertical axis can represent the high and low quality factor (Q value).

[0101] in, Figure 11 (a) in Figure 5 The admittance curve of the surface acoustic wave resonator 100 is shown in FIG. Figure 11 (b) in the Figure 10 The admittance curve of the surface acoustic wave resonator 100 is shown in FIG. Figure 11 As can be seen from (a), Figure 5 The surface acoustic wave resonator 100 shown in the figure generates a lot of transverse mode noise while exciting the main mode, thereby reducing the performance of the surface acoustic wave resonator 100. Figure 11 As can be seen from (b), Figure 10 The transverse mode noise of the surface acoustic wave resonator 100 of the embodiment shown is weak or disappears (that is, weak / no in the figure), that is, Figure 10 The surface acoustic wave resonator 100 of the illustrated embodiment mainly excites the main mode, thereby improving the performance of the surface acoustic wave resonator 100 .

[0102] See also Figure 12 , Figure 12 for Figure 10 The planar structural diagram of the interdigital transducer 20 of the surface acoustic wave resonator 100 shown is the same as the embodiment shown above in that the interdigital transducer 20 of the embodiment of the present application also includes a first bus bar 21, a second bus bar 22, a plurality of first interdigital electrodes 23 and a plurality of second interdigital electrodes 24, wherein the arrangement of the first bus bar 21, the second bus bar 22, the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 on the preset surface 11 can be seen above and will not be repeated here.

[0103] In some embodiments, see Figure 10, the first excitation segment 20a and the first reflection segment 20c may both be located on the first interdigitated electrode 23. In other embodiments, see Figure 13 , Figure 13 for Figure 10 The schematic cross-sectional structure diagram of the surface acoustic wave resonator 100 is shown. The first excitation segment 20a and the first reflection segment 20c may also be located on the second interdigital electrode 24, but this is not a limitation in the present application. For example, the first excitation segment 20a and the first reflection segment 20c may be disposed on the first interdigital electrode 23, and the second excitation segment and the second reflection segment may be disposed on the second interdigital electrode 24. The configuration of the second excitation segment may refer to the configuration of the first excitation segment 20a, and the configuration of the second reflection segment may refer to the configuration of the first reflection segment 20c. For ease of explanation, the following description will take the first interdigital electrode 23 as an example.

[0104] In some embodiments, the surface acoustic wave resonator 100 has a first sound velocity zone A1 and a third sound velocity zone A3, the third sound velocity zone A3 is located on one side of the first sound velocity zone A1 in the second direction L2, the first piezoelectric layer 51 and the first excitation segment 20a are located in the first sound velocity zone A1, that is, the first piezoelectric layer 51 and the first excitation segment 20a are stacked in the first direction L1 to form the first sound velocity zone A1, the first transition segment 20b and the non-piezoelectric layer 52 are located in the third sound velocity zone A3, that is, the first transition segment 20b and the non-piezoelectric layer 52 are stacked in the first direction L1 to form the third sound velocity zone A3.

[0105] The first sound velocity zone A1 forms the main excitation area of ​​the surface acoustic wave, that is, the first sound velocity zone A1 of the embodiment of the present application has the same function as the first sound velocity zone A1 above, and the surface acoustic wave excited by the first sound velocity zone A1 can be transmitted to the outside, that is, to the side of the third sound velocity zone A3, and be reflected by the third sound velocity zone A3, that is, the third sound velocity zone A3 of the embodiment of the present application can be Figure 5 The third sonic velocity region A3 is the same as above.

[0106] In this way, by introducing the non-piezoelectric layer 52 in the third sound velocity zone A3, no acoustic interference occurs between the first sound velocity zone A1 and the third sound velocity zone A3. That is, the surface acoustic waves excited by the first sound velocity zone A1 will not be transmitted to the third sound velocity zone A3, and the third sound velocity zone A3 itself does not excite surface acoustic waves, so that the number of surface acoustic waves oscillating in the third sound velocity zone A3 is relatively small, and most of the surface acoustic waves excited by the first sound velocity zone A1 are still concentrated in the first sound velocity zone A1, so that the surface acoustic wave resonator 100 of the embodiment of the present application forms a main mode excitation, reducing the generation of transverse mode noise.

[0107] In some embodiments, to prevent surface acoustic waves from propagating from the first sound velocity zone A1 to the third sound velocity zone A3, the sound velocity of the surface acoustic wave in the first reflection section 20c is different from the sound velocity of the surface acoustic wave in the first excitation section 20a. That is, the sound velocity of the surface acoustic wave in the first sound velocity zone A1 is less than or greater than the sound velocity of the surface acoustic wave in the third sound velocity zone A3, and at the same time, the third sound velocity zone A3 does not excite surface acoustic waves. This prevents interference between the third sound velocity zone A3 and the first sound velocity zone A1, specifically manifesting as discontinuous surface acoustic wave propagation between the first sound velocity zone A1 and the third sound velocity zone A3. The third sound velocity zone A3 forms a reflective structure for the first sound velocity zone A1, effectively reflecting the surface acoustic wave from the first sound velocity zone A1.

[0108] In other embodiments, in addition to the difference between the sound speeds, reflection can also be formed between the first sound speed zone A1 and the third sound speed zone A3 by setting other parameters of the first reflection segment 20c and the first excitation segment 20a differently. This application does not limit or list these differences here.

[0109] Generally, the sound speed of different sound speed zones depends on the material properties, materials and thickness of each layer in the area. In some embodiments, the sound speed of the first sound speed zone A1 and the third sound speed zone A3 can be made different by setting the thickness of the first reflection segment 20c and the first excitation segment 20a in the first direction L1 to be different, which is simple to manufacture and low in cost.

[0110] For example, see Figure 10 , at this time, the thickness of the first reflecting segment 20c in the first direction L1 is greater than the thickness of the first exciting segment 20a in the first direction L1. In other embodiments, please refer to Figure 14 , Figure 14 The cross-sectional structural diagram of the surface acoustic wave resonator 100 provided in other embodiments of the present application, the thickness of the first reflection segment 20c in the first direction L1 may also be smaller than the thickness of the first excitation segment 20a in the first direction L1, and the present application does not impose any limitation thereto.

[0111] It can be understood that when the thickness of the first reflection segment 20c in the first direction L1 is greater than the thickness of the first excitation segment 20a in the first direction L1, the sound velocity of the first sound velocity zone A1 is greater than the sound velocity of the second sound velocity zone. Similarly, when the thickness of the first reflection segment 20c in the first direction L1 is less than the thickness of the first excitation segment 20a in the first direction L1, the sound velocity of the first sound velocity zone A1 is less than the sound velocity of the second sound velocity zone. In the embodiment of the present application, under the premise that the first reflection segment 20c and the non-piezoelectric layer 52 are directly opposite and do not excite surface acoustic waves, as long as the sound velocity of the surface acoustic wave in the first reflection segment 20c is not equal to the sound velocity of the surface acoustic wave in the first excitation segment 20a, the third sound velocity zone A3 can reflect the surface acoustic wave transmitted from the first sound velocity zone A1.

[0112] In some embodiments, please refer to Figure 10 、 Figures 12 to 14 The IDT 20 further includes a first transition section 20b, which is located between the first excitation section 20a and the first reflection section 20c. The first transition section 20b is directly opposite the non-piezoelectric layer 52 in the first direction L1. The first excitation section 20a, the first transition section 20b, and the first reflection section 20c can be sequentially arranged on the first interdigital electrode 23 along the second direction L2. Furthermore, surface acoustic waves are not excited in the areas where the first reflection section 20c and the first transition section 20b are located.

[0113] The surface acoustic wave excited in the area where the first excitation segment 20a is located can be transmitted to the area where the first transition segment 20b is located, and then reflected back to the first transition segment 20b by the first reflection segment 20c, and then transmitted to the first excitation segment 20a, forming a round trip of the surface acoustic wave. At this time, the first transition segment 20b and the first reflection segment 20c are both directly opposite the non-piezoelectric layer 52. When preparing the surface acoustic wave resonator 100, it is only necessary to ensure that the first excitation segment 20a is directly opposite the first piezoelectric layer 51, thereby reducing the preparation accuracy of the boundary of the non-piezoelectric layer 52. There is no need to ensure that the orthographic projection of the first reflection segment 20c on the non-piezoelectric layer 52 completely overlaps with the non-piezoelectric layer 52, thereby reducing the difficulty of the process preparation.

[0114] Furthermore, by disposing the first transition section 20 b , the propagation path of the surface acoustic wave of the first excitation section 20 a is extended, and the generation of transverse mode clutter can also be effectively suppressed.

[0115] In some embodiments, the surface acoustic wave resonator 100 further includes a second acoustic velocity region A2, which is located on one side of the first acoustic velocity region A1 in the second direction L2. A third acoustic velocity region A3 is located on the side of the second acoustic velocity region A2 in the second direction L2 away from the first acoustic velocity region A1, thereby forming the first acoustic velocity region A1, the second acoustic velocity region A2, and the third acoustic velocity region A3 arranged sequentially along the second direction L2. The first transition section 20b and a portion of the non-piezoelectric layer 52 are located in the second acoustic velocity region A2, and the first reflective section 20c and another portion of the non-piezoelectric layer 52 are located in the third acoustic velocity region A3.

[0116] See also Figure 14 The non-piezoelectric layer 52 is defined as comprising a first portion 521 and a second portion 522. The first portion 521 directly faces the first transition section 20b, while the second portion 522 directly faces the first reflective section 20c. In this case, the first portion 521 forms the inner boundary of the second portion 522. When fabricating the non-piezoelectric layer 52 on the second portion 522, the presence of the first portion 521 reduces the difficulty of fabricating the non-piezoelectric layer 52. Furthermore, since both the second portion 522 and the first portion 521 are non-piezoelectric layers 52, surface acoustic waves are not excited in the second sound velocity zone A2 and the third sound velocity zone A3.

[0117] In some embodiments, to achieve reciprocating surface acoustic wave transmission between the first sound velocity region A1 and the second sound velocity region A2, the sound velocity of the surface acoustic wave in the first excitation segment 20a is equal to the sound velocity of the surface acoustic wave in the first transition segment 20b, thereby achieving continuous surface acoustic wave transmission between the first sound velocity region A1 and the second sound velocity region A2. For example, to achieve the same sound velocity of the surface acoustic wave in the first sound velocity region A1 and the second sound velocity region A2, the thickness of the first excitation segment 20a in the first direction L1 can be equal to the thickness of the first transition segment 20b in the first direction L1, thereby achieving continuous reciprocating surface acoustic wave transmission between the first sound velocity region A1 and the second sound velocity region A2.

[0118] exist Figure 10 、 Figures 12 to 14 In the illustrated embodiment, both the second sound velocity zone A2 and the third sound velocity zone A3 include two zones. The two second sound velocity zones A2 are located on opposite sides of the first sound velocity zone A1 in the second direction L2, and the two third sound velocity zones A3 are located on opposite sides of the second sound velocity zone A2 in the second direction L2. In some embodiments, each second sound velocity zone A2 can include a first transition section 20b and a first portion 521 of the non-piezoelectric layer 52, and each third sound velocity zone A3 can include a first reflection section 20c and a second portion 522 of the non-piezoelectric layer 52. In this way, the third sound velocity zones A3 can reflect surface acoustic waves from opposite sides of the first sound velocity zone A1 in the second direction L2, thereby enhancing the excitation effect of the main mode.

[0119] In other embodiments, the first transition section 20b and the first part 521 of the non-piezoelectric layer 52 may be arranged only in the second sound speed zone A2 on the second direction L2 side of the first sound speed zone A1, and the first reflection section 20c and the second part 522 of the non-piezoelectric layer 52 may be arranged in the third sound speed zone A3. This application does not impose any restrictions on this.

[0120] In some embodiments, the first portion 521 of the non-piezoelectric layer 52 and the second portion 522 of the non-piezoelectric layer 52 have the same thickness and acoustic impedance. In this way, the non-piezoelectric layer 52 can be prepared using the same material and processed in one go, thereby simplifying the preparation process of the substrate assembly 50.

[0121] In some embodiments, please refer to Figure 10 、 Figures 12 to 14The surface acoustic wave resonator 100 further includes a fourth sound velocity region A4 and a fifth sound velocity region A5. The fourth sound velocity region A4 is located on both sides of the third sound velocity region A3 in the second direction L2, and the fifth sound velocity region A5 is located on both sides of the fourth sound velocity region A4 in the second direction L2. Thus, in the second direction L2, the fifth sound velocity region A5, the fourth sound velocity region A4, the third sound velocity region A3, the second sound velocity region A2, the first sound velocity region A1, the second sound velocity region A2, the third sound velocity region A3, the fourth sound velocity region A4, and the fifth sound velocity region A5 are arranged in sequence.

[0122] See also Figure 15 , Figure 15 for Figure 10 The phase velocity (sound speed)-position diagram of the surface acoustic wave resonator 100 corresponding to different sound speed zones is shown. Here, the sound speed in the first sound speed zone A1 is a1, the sound speed in the second sound speed zone A2 is a2, the sound speed in the third sound speed zone A3 is a3, the sound speed in the fourth sound speed zone A4 is a4, and the sound speed in the fifth sound speed zone A5 is a5. As can be seen from the above, in some embodiments, a1 is equal to a2, and a3 is less than a2. Furthermore, because the metallization ratio of the fourth sound speed zone A4 (i.e., the projected area of ​​the IDT 20 on the preset surface 11 / the total area of ​​the fourth sound speed zone A4) is less than the metallization ratio of the first sound speed zone A1, a4 is greater than a1. Similarly, because the metallization ratio of the fifth sound speed zone A5 is greater than the metallization ratio of the first sound speed zone A1, a5 is less than a1.

[0123] In some embodiments, the first piezoelectric layer 51 and the non-piezoelectric layer 52 are made of the same material. For example, the piezoelectric layer and the non-piezoelectric layer 52 can both be made of lithium niobate or lithium tantalate. Different processes are used to form the first piezoelectric layer 51 with piezoelectric properties and a specific crystal orientation, and the isotropic non-piezoelectric layer 52 without piezoelectric properties or with a crystal orientation and piezoelectric properties different from the first piezoelectric layer 51. In this way, the thickness and material between the first sound velocity zone A1 and the second sound velocity zone A2 are the same, ensuring that the sound speeds in the first sound velocity zone A1 and the second sound velocity zone A2 are the same, allowing surface acoustic waves to propagate back and forth between the first sound velocity zone A1 and the second sound velocity zone A2.

[0124] In other embodiments, the first piezoelectric layer 51 and the non-piezoelectric layer 52 have the same thickness in the first direction L1, and the first piezoelectric layer 51 and the non-piezoelectric layer 52 have the same acoustic impedance. In this way, the material properties of the first piezoelectric layer 51 and the non-piezoelectric layer 52 are the same, and the sound speeds in the first sound speed zone A1 and the second sound speed zone A2 are the same.

[0125] In other embodiments, the sound velocities in the first sound velocity zone A1 and the second sound velocity zone A2 may be made the same by setting other parameters of the first piezoelectric layer 51 and the non-piezoelectric layer 52. This application does not limit this.

[0126] In some embodiments, see Figure 10 、 Figure 14 and Figure 16 , Figure 16 The cross-sectional structure diagram of the surface acoustic wave resonator 100 provided in other embodiments of the present application shows that, in the first direction L1, the thickness of the non-piezoelectric layer 52 is equal to the thickness of the first piezoelectric layer 51. That is, in the first direction L1, the non-piezoelectric layer 52 is not provided at the location where the first piezoelectric layer 51 is provided, and the first piezoelectric layer 51 is not provided at the location where the non-piezoelectric layer 52 is provided. The first piezoelectric layer 51 and the non-piezoelectric layer 52 are not stacked in the first direction L1. This simplifies the manufacturing process when preparing the substrate assembly 50.

[0127] Specifically, Figure 10 Take the manufacturing process of the surface acoustic wave resonator 100 as an example, please refer to Figure 17 , Figure 17 for Figure 10 The schematic diagram of the preparation process of the substrate assembly 50 of the surface acoustic wave resonator 100 is shown, and the specific process is as follows:

[0128] Step S1: providing a piezoelectric material layer 60;

[0129] Step S2: etching the piezoelectric material layer 60 to form a through hole 61 by etching or other processes;

[0130] Step S3: coating a non-piezoelectric material layer 70 on one side of the piezoelectric material layer 60 by a coating process, etc. At this time, the portion of the non-piezoelectric material layer 70 that enters the through hole 61 forms the non-piezoelectric layer 52, and the portion that falls on one side of the piezoelectric material layer 60 forms a redundant portion;

[0131] Step S4 : removing the redundant non-piezoelectric material layer 70 on one side of the piezoelectric material layer 60 through a cleaning process, thereby obtaining a completed substrate assembly 50 .

[0132] In some embodiments, the through hole 61 on the piezoelectric substrate 10 may extend to the boundary of the piezoelectric substrate 10 in the second direction L2, that is, Figure 14 and Figure 16 In the embodiment, the periphery of the first piezoelectric layer 51 is surrounded by only the non-piezoelectric layer 52. In other embodiments, the through hole 61 on the piezoelectric substrate 10 can also be embedded, that is, Figure 10In the illustrated embodiment, the substrate assembly 50 further includes a second piezoelectric layer 53. In this case, the second piezoelectric layer 53 and the first piezoelectric layer 51 can be different portions of an integrally formed piezoelectric material layer 60. That is, the material and thickness of the second piezoelectric layer 53 can be identical to those of the first piezoelectric layer 51. By forming the through hole 61, the portions on both sides of the through hole 61 form the first piezoelectric layer 51 and the second piezoelectric layer 53, respectively. Thus, when the non-piezoelectric layer 52 is formed within the through hole 61, the second piezoelectric layer 53 is located on the periphery of the non-piezoelectric layer 52, and the non-piezoelectric layer 52 is located on the periphery of the first piezoelectric layer 51.

[0133] so, Figure 17 During the preparation process of the piezoelectric substrate 10 of the illustrated embodiment, only the holes 61 need to be drilled without considering the drilling depth, thereby simplifying the preparation of the surface acoustic wave resonator 100 and reducing the process precision requirements, thereby reducing costs and improving economic benefits.

[0134] Understandably, in Figure 10 、 Figure 14 and Figure 16 In the surface acoustic wave resonator 100 of the embodiment shown, only the non-piezoelectric layer 52 is included in the second acoustic velocity region A2 and the third acoustic velocity region A3. In other embodiments, the second acoustic velocity region A2 and the third acoustic velocity region A3 may also include the non-piezoelectric layer 52 and the third piezoelectric layer 54 (see below). Figure 18 ) are arranged in a superimposed manner in the first direction L1, and the non-piezoelectric layer 52 is arranged on a side of the third piezoelectric layer 54 facing the IDT 20.

[0135] For details, please refer to Figure 18 , Figure 18 The cross-sectional structure diagram of the surface acoustic wave resonator 100 provided in some other embodiments of the present application is shown in FIG. Figure 18 In this embodiment, the substrate assembly 50 further includes a third piezoelectric layer 54, which is positioned around the first piezoelectric layer 51. The non-piezoelectric layer 52 and at least a portion of the third piezoelectric layer 54 are stacked along the first direction L1, with the non-piezoelectric layer 52 positioned between the IDT 20 and the third piezoelectric layer 54. Thus, a stacked arrangement of the first reflective segment 20c, the non-piezoelectric layer 52, and the third piezoelectric layer 54 is formed in the third acoustic velocity region A3, ensuring that the first reflective segment 20c does not excite surface acoustic waves on the piezoelectric substrate 10.

[0136] Understandably, Figure 18 In the embodiment shown, the third piezoelectric layer 54 is arranged in the second sound velocity region A2, the third sound velocity region A3, the fourth sound velocity region A4 and the fifth sound velocity region A5. Figure 19 , Figure 19 for Figure 18 The schematic diagram of the preparation process of the substrate assembly 50 of the surface acoustic wave resonator 100 is shown, and the specific process is as follows:

[0137] Step S1: providing a piezoelectric material layer 60;

[0138] Step S2: etching the piezoelectric material layer 60 to form a hollow groove 62 by etching or other processes, wherein the depth of the hollow groove 62 is less than the thickness of the piezoelectric substrate 10;

[0139] Step S3: coating a non-piezoelectric material layer 70 on one side of the piezoelectric material layer 60 by a coating process, etc. At this time, the portion of the non-piezoelectric material layer 70 that enters the empty groove 62 forms the non-piezoelectric layer 52, and the portion that falls on one side of the piezoelectric material layer 60 forms a redundant portion;

[0140] Step S4 : removing the redundant non-piezoelectric material layer 70 on one side of the surface of the piezoelectric substrate 10 through a cleaning process, thereby obtaining a complete substrate assembly 50 .

[0141] In the above Figure 19 In the embodiment shown, the empty groove 62 is an embedded groove, which does not extend to the edge of the substrate assembly 50 in the second direction L2. At this time, part of the third piezoelectric layer 54 is located on the periphery of the non-piezoelectric layer 52. In this way, when manufacturing the substrate assembly 50, less waste of the piezoelectric material layer 60 can be achieved, thereby reducing the manufacturing cost.

[0142] In some other embodiments, the slot 62 may also extend to the boundary of the substrate assembly 50 in the second direction L2, that is, see Figure 20 and Figure 21 , Figure 20 Schematic diagram of the cross-sectional structure of the surface acoustic wave resonator 100 provided in some embodiments of the present application, Figure 21 The cross-sectional structural diagram of the surface acoustic wave resonator 100 provided in some other embodiments of the present application, the non-piezoelectric layer 52 and the third piezoelectric layer 54 are both arranged around the periphery of the first piezoelectric layer 51, and the positive projection of the non-piezoelectric layer 52 on the third piezoelectric layer 54 coincides with the boundary of the third piezoelectric layer 54. At this time, there is no need to consider the boundary positions on both sides of the hollow groove 62. It is only necessary to open the hollow groove 62 at a determined position and extend it to the boundary position of the substrate assembly 50 in the second direction L2, thereby reducing the difficulty and accuracy of preparation.

[0143] In some embodiments, see Figure 21In the first direction L1, the thickness of the non-piezoelectric layer 52 is h1, and the thickness of the third piezoelectric layer 54 stacked with the non-piezoelectric layer 52 in the first direction L1 is h2. h1 / (h1+h2) is greater than or equal to 20% and less than or equal to 100%, wherein h1+h2 can be understood as the total thickness of the substrate assembly 50, thereby ensuring that the layer thickness of the non-piezoelectric layer 52 is within a suitable range to ensure the effectiveness of not exciting surface acoustic waves in the third sound velocity zone A3. Exemplarily, the thickness of the non-piezoelectric layer 52 can be 20%, 40%, 80%, 100%, etc. of the total thickness of the substrate assembly 50. It can be understood that when the thickness of the non-piezoelectric layer 52 is equal to the total thickness of the substrate assembly 50, the piezoelectric substrate 10 is formed. Figure 10 The surface acoustic wave resonator 100 in the illustrated embodiment.

[0144] The surface acoustic wave resonator 100 of any of the above embodiments can be applied to Figure 1 The filter 100a shown is placed in the electronic device 1000 for filtering, and can also be directly used in the electronic device 1000 for filtering, which is not limited in this application.

[0145] 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.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A surface acoustic wave resonator, characterized in that: include: A substrate assembly comprising a first piezoelectric layer and a non-piezoelectric layer, wherein the non-piezoelectric layer is located on the periphery of the first piezoelectric layer; an interdigital transducer, stacked with the substrate assembly along a first direction; The IDT comprises a first excitation segment and a first reflection segment, the first excitation segment is directly opposite to the first piezoelectric layer in the first direction, the first reflection segment is directly opposite to the non-piezoelectric layer in the first direction, and surface acoustic waves can be reflected by the first reflection segment to the first excitation segment; The IDT further includes a first transition section, the first transition section is located between the first excitation section and the first reflection section, and the first transition section is directly opposite to the non-piezoelectric layer in the first direction; Surface acoustic waves can be transmitted from the first excitation section to the first transition section, and surface acoustic waves can also be transmitted from the first transition section to the first excitation section.

2. The surface acoustic wave resonator according to claim 1, wherein The sound velocity of the surface acoustic wave in the first reflection section is not equal to the sound velocity in the first excitation section.

3. The surface acoustic wave resonator according to claim 1, wherein The thickness of the first reflection segment is greater than or less than the thickness of the first excitation segment.

4. The surface acoustic wave resonator according to claim 1, wherein The sound velocity of the surface acoustic wave in the first excitation section is equal to the sound velocity in the first transition section.

5. The surface acoustic wave resonator according to claim 4, characterized in that In the first direction, the thickness of the first excitation segment is equal to the thickness of the first transition segment.

6. The surface acoustic wave resonator according to claim 4, characterized in that The non-piezoelectric layer includes a first portion and a second portion, the first portion is opposite to the first transition section in the first direction, and the second portion is opposite to the first reflection section in the first direction; The first portion and the second portion have the same thickness in the first direction, and the first portion and the second portion have the same acoustic impedance.

7. The surface acoustic wave resonator according to claim 1, wherein The surface acoustic wave resonator has a first sound velocity region, a second sound velocity region, and a third sound velocity region, wherein the second sound velocity region is located on one side of the first sound velocity region in the second direction, and the third sound velocity region is located on the side of the second sound velocity region away from the first sound velocity region in the second direction, and the first direction is perpendicular to the second direction; The first piezoelectric layer and the first excitation segment are located in a first sound speed zone, the first transition segment and a portion of the non-piezoelectric layer are located in a second sound speed zone, and the first reflection segment and another portion of the non-piezoelectric layer are located in a third sound speed zone.

8. The surface acoustic wave resonator according to claim 7, characterized in that The second sound speed zone and the third sound speed zone each include two, the two second sound speed zones are located on opposite sides of the first sound speed zone in the second direction, and the two third sound speed zones are located on opposite sides of the second sound speed zone in the second direction; Each of the second sound speed zones includes the first transition section and the non-piezoelectric layer, each of the third sound speed zones includes the first reflection section and the non-piezoelectric layer, and the second direction is perpendicular to the first direction.

9. The surface acoustic wave resonator according to claim 1, wherein The first piezoelectric layer and the non-piezoelectric layer are made of the same material; Alternatively, the first piezoelectric layer and the non-piezoelectric layer have the same thickness in the first direction, and the first piezoelectric layer and the non-piezoelectric layer have the same acoustic impedance.

10. The surface acoustic wave resonator according to claim 1, wherein In the first direction, the thickness of the non-piezoelectric layer is equal to the thickness of the first piezoelectric layer.

11. The surface acoustic wave resonator according to claim 10, wherein The substrate assembly further includes a second piezoelectric layer located outside the non-piezoelectric layer.

12. The surface acoustic wave resonator according to claim 1, wherein The substrate assembly further includes a third piezoelectric layer, wherein the third piezoelectric layer is located on the periphery of the first piezoelectric layer; At least a portion of the non-piezoelectric layer and the third piezoelectric layer are stacked along the first direction, and the non-piezoelectric layer is located between the interdigital transducer and the third piezoelectric layer.

13. The surface acoustic wave resonator according to claim 12, wherein: In the first direction, the thickness of the non-piezoelectric layer is h1, the thickness of the third piezoelectric layer stacked with the non-piezoelectric layer in the first direction is h2, and h1 / (h1+h2) is greater than or equal to 20%.

14. The surface acoustic wave resonator according to claim 1, wherein The surface acoustic wave resonator further includes a base layer, the substrate assembly is disposed on the base layer, and the interdigital transducer is located on a side of the substrate assembly away from the base layer.

15. The surface acoustic wave resonator according to claim 1, wherein The surface acoustic wave resonator further includes a functional layer, which is provided on a side of the interdigital transducer facing away from the substrate assembly.

16. A filter, characterized in that: The surface acoustic wave resonator comprises the surface acoustic wave resonator according to any one of claims 1 to 15.

17. An electronic device, characterized in that: The electronic device comprises the surface acoustic wave resonator according to any one of claims 1 to 15; or the electronic device comprises the filter according to claim 16.

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