Surface acoustic wave resonator, filter, and electronic device

Abstract

The invention discloses a surface acoustic wave resonator, a filter and electronic equipment, and relates to the technical field of resonators, the surface acoustic wave resonator comprises a substrate assembly and an interdigital transducer, the substrate assembly comprises 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 arranged in a stacked mode in the first direction, and the interdigital transducer is located on the periphery of the non-piezoelectric layer. The interdigital transducer is provided with a first excitation section and a first reflection section, the first excitation section directly faces the first piezoelectric layer in the first direction, the first reflection section directly faces the non-piezoelectric layer in the first direction, and the surface acoustic wave can be reflected to the first excitation section by the first reflection section.

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 development of communication technology, the amount of resonators required for electronic devices such as smartphones will increase significantly. Among them, the surface acoustic wave resonator (SAW) is widely used. The surface acoustic wave resonator uses the piezoelectric effect to achieve electric-acoustic-electric transduction and has the advantages of small structural size. In addition, through the series and parallel connection of the surface acoustic wave resonator, a radio frequency filter with low insertion loss and high rectangular coefficient can be realized.

[0003] In a surface acoustic wave resonator, while exciting the main mode, it will also generate 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 lateral modes and improve the working performance of the filter.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions: In a first aspect, the present application provides a surface acoustic wave resonator, comprising a substrate assembly and an interdigital transducer, the substrate assembly comprising a first piezoelectric layer and a non-piezoelectric layer, the non-piezoelectric layer being located at 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.

[0006] In the surface acoustic wave resonator of the embodiment of the present application, the surface acoustic wave excited in the area where the first excitation segment is located is reflected back to the area where the first excitation segment is located in large quantities, and will not be transmitted to other areas. At the same time, the area where the first reflection segment is located itself will not excite the surface acoustic wave, nor will it be transmitted to other areas, thereby avoiding the situation where the first reflection segment itself generates the surface acoustic wave and causes the existence of transverse mode clutter. At the same time, the surface acoustic wave transmitted from the first excitation segment can be reflected by the first reflection segment, thereby effectively suppressing the generation of transverse mode clutter and achieving the effect of mainly exciting the transverse mode.

[0007] In a possible implementation of the first aspect, the 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 preset surface and spaced apart along the second direction, the plurality of first interdigital electrodes and the plurality of second interdigital electrodes are both attached to the preset surface, and the first interdigital electrodes and the second interdigital electrodes are spaced apart and arranged alternately and in parallel along the third direction. In this way, a second interdigital electrode is arranged between two adjacent first interdigital electrodes, and a first interdigital electrode is arranged between two adjacent second interdigital electrodes. One end of the 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 the second interdigital electrode is connected to the second bus bar, and the other end is spaced apart from the first bus bar. That is to say, each first interdigital electrode and each second interdigital electrode are located between the first bus bar and the second bus bar, and the first interdigital electrode is connected to the first bus bar, and the second interdigital electrode is connected to the second bus bar. The first direction, the second direction, and the third direction 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 both be located on the second interdigital electrode, which is not limited in the present application. Exemplarily, the first excitation segment and the first reflection segment may be arranged on the first interdigital electrode, and the second excitation segment and the second reflection segment may be arranged on the second interdigital electrode, so as to achieve the superposition effect of the excitation segment and the reflection segment.

[0008] 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.

[0009] The first sound velocity zone forms the main excitation area of ​​the surface acoustic wave, that is, the first sound velocity zone of the embodiment of the present application has the same function as the first sound velocity zone in the above text, and the surface acoustic wave excited by the first sound velocity zone can be transmitted to the outside, that is, to one side of the third sound velocity zone, and be reflected by the third sound velocity zone, that is, the third sound velocity zone of the embodiment of the present application can be the same as the third sound velocity zone in the above text of the figure.

[0010] In this way, by introducing the non-piezoelectric layer in the third sound velocity zone, there will be no acoustic interference 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 and reduces the generation of transverse mode noise.

[0011] In a possible implementation of the first aspect, 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, that is, the sound velocity of the surface acoustic wave in the first sound velocity zone is less than or greater than the sound velocity of the surface acoustic wave in the third sound velocity zone, and at the same time, the third sound velocity zone does not excite the surface acoustic wave. In this way, interference between the third sound velocity zone and the first sound velocity zone can be avoided, which is specifically manifested in that the surface acoustic wave transmission between the first sound velocity zone and the third sound velocity zone is discontinuous, and the third sound velocity zone forms a reflection structure of the first sound velocity zone, thereby achieving effective reflection of the surface acoustic wave in the first sound velocity zone.

[0012] In a 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 speeds of different sound speed zones depend on the material properties, materials, and thicknesses of each layer in the region. In some embodiments, the sound speeds of the first sound speed zone and the third sound speed zone can be different by setting the thicknesses of the first reflection segment and the first excitation segment in the first direction to be different, which is simple to manufacture and low in cost.

[0013] 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 the embodiment of the present application, under the premise that the first reflection segment and the non-piezoelectric layer are directly opposite to each other 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.

[0014] In a possible implementation of the first aspect, the interdigital transducer 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. In this case, the first excitation section, the first transition section, and the first reflection section can be sequentially arranged on the first interdigital electrode along the second direction. In addition, the areas where the first reflection section and the first transition section are located do not excite surface acoustic waves.

[0015] The surface acoustic wave excited in the area where the first excitation segment is located can be transmitted to the area where the first transition segment is located, and then reflected back to the first transition segment by the first reflection segment, and then transmitted to the first excitation segment, forming a round trip of the surface acoustic wave. At this time, the first transition segment and the first reflection segment are both directly opposite to the non-piezoelectric layer. When preparing the surface acoustic wave resonator, it is only necessary to ensure that the first excitation segment is directly opposite to the first piezoelectric layer, thereby reducing the preparation accuracy of the boundary of the non-piezoelectric layer, and there is no 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 reducing the difficulty of process preparation.

[0016] Furthermore, by providing the first transition section, the propagation path of the surface acoustic wave of the first excitation section is extended, and the generation of transverse mode clutter can also be effectively suppressed.

[0017] In a possible implementation of the first aspect, the surface acoustic wave resonator further includes a second sound velocity zone, the second sound velocity zone is located on one side of the first sound velocity zone in the second direction, and the third sound velocity zone is located on the side of the second sound velocity zone away from the first sound velocity zone in the second direction, so that the first sound velocity zone, the second sound velocity zone, and the third sound velocity zone are arranged in sequence 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. The reciprocating transmission of the surface acoustic wave between the first sound velocity zone and the second sound velocity zone is realized.

[0018] In a possible implementation of the first aspect, the acoustic velocity of the surface acoustic wave in the first excitation section is equal to the acoustic velocity in the first transition section. In this way, continuous transmission of the surface acoustic wave is formed between the first sound velocity zone and the second sound velocity zone. Exemplarily, in order to achieve the same sound velocity of the surface acoustic wave in the first sound velocity zone and the second sound velocity zone, the thickness of the first excitation section in the first direction can be made equal to the thickness of the first transition section in the first direction, so that continuous reciprocating transmission of the surface acoustic wave is formed between the first sound velocity zone and the second sound velocity zone.

[0019] In a possible implementation of the first aspect, the non-piezoelectric layer includes a first part and a second part, the first part is opposite to the first transition section in the first direction, and the second part is opposite to the first reflection section in the first direction. The first part forms an inner boundary of the second part, and when the non-piezoelectric layer is prepared for the second part, the difficulty of preparing the non-piezoelectric layer is reduced due to the existence of the second part. At the same time, since both the second part and the first part are non-piezoelectric layers, it is ensured that no surface acoustic waves are excited in the second sound velocity zone and the third sound velocity zone.

[0020] In a 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. In this way, the non-piezoelectric layer can be formed by one-time processing using the same material, thereby simplifying the preparation process of the substrate assembly.

[0021] In a possible implementation of the first aspect, the second sound velocity zone and the third sound velocity zone each include two, the two second sound velocity zones are located on opposite sides of the first sound velocity zone in the second direction, 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, each third sound velocity zone includes a first reflection section and a non-piezoelectric layer, and the second direction is perpendicular to the first direction. In this way, the third sound velocity zone can reflect the surface acoustic wave from the opposite sides of the first sound velocity zone in the second direction to improve the main mode excitation effect.

[0022] In a 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 be made of lithium niobate or lithium tantalate, and different processes are used to form a first piezoelectric layer with piezoelectric properties with a specific crystal orientation, and an isotropic non-piezoelectric layer without piezoelectric properties or with a crystal orientation and piezoelectric properties different 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 to ensure that the sound velocities in the first sound velocity zone and the second sound velocity zone are the same, so that the surface acoustic wave can be transmitted back and forth between the first sound velocity zone and the second sound velocity zone.

[0023] In a 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. In this way, the material properties of the first piezoelectric layer and the non-piezoelectric layer are the same, and the sound speeds in the first sound speed zone and the second sound speed zone are the same.

[0024] In a 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 position where the first piezoelectric layer is provided is not provided with the non-piezoelectric layer, and the position where the non-piezoelectric layer is provided is not provided with the first piezoelectric layer, and 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 considering the drilling depth, thereby simplifying the preparation of the surface acoustic wave resonator and reducing the process manufacturing precision requirements, reducing costs and improving economic benefits.

[0025] In a possible implementation of the first aspect, the substrate assembly further includes a second piezoelectric layer, and the second piezoelectric layer is located at the periphery of the non-piezoelectric layer, so as to avoid a large amount of waste of piezoelectric materials.

[0026] In a possible implementation of the first aspect, the substrate assembly further includes a third piezoelectric layer, the third piezoelectric layer is located at 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 sequentially arranged 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.

[0027] In a possible implementation of the first aspect, 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%. This ensures that the layer thickness of the non-piezoelectric layer is within a suitable range to ensure the effectiveness of not exciting surface acoustic waves in the third sound velocity zone.

[0028] In a 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 interdigital transducer is located on a side of the substrate assembly away from the base layer. The base layer is disposed at the bottom to serve as a substrate for other layers, carrying and supporting other hierarchical structures (including but not limited to the functional layer, the interdigital transducer, and the substrate assembly).

[0029] In a possible implementation of the first aspect, the surface acoustic wave resonator further comprises a functional layer, which is disposed on a side of the interdigital transducer away from the substrate assembly. The functional layer can provide different functions, for example, the functional layer can form a temperature compensation function for temperature compensation of the surface acoustic wave resonator, in which case the surface acoustic wave resonator is a temperature compensation surface acoustic wave device, and the functional layer can form a passivation function for protection, in which case the surface acoustic wave resonator is a thin film surface acoustic wave device.

[0030] In the second aspect, the present application provides a filter, the filter includes a surface acoustic wave resonator of any of the above embodiments, the main working principle of the surface acoustic wave resonator is to use the piezoelectric characteristics of piezoelectricity, and use input and output transducers to convert the input signal of the radio wave into mechanical energy, and after processing, convert the mechanical energy into an electrical signal to achieve the goal of filtering unnecessary signals and noise and improving the quality of signal reception. The filter uses the surface acoustic wave resonator to effectively filter out the frequency point of a specific frequency in the signal or the frequency outside the frequency point, obtain a signal of a specific frequency, or eliminate the signal after a specific frequency, so as to improve the working performance of the electronic device.

[0031] In a third aspect, the present application provides an electronic device comprising the surface acoustic wave resonator of any of the above embodiments.

[0032] In a fourth aspect, the present application provides an electronic device comprising the filter of any of the above embodiments.

[0033] Among them, the technical effects brought about by the second to fourth aspects can also refer to the technical effects brought about by different design methods in the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the structure of an electronic device provided in some embodiments of the present application; Figure 2A schematic cross-sectional structure diagram of a surface acoustic wave resonator provided in some embodiments of the present application; Figure 3 for Figure 2 A schematic diagram of the planar structure of the interdigital transducer of the surface wave resonator shown; Figure 4 for Figure 3 The phase velocity (sound speed)-position diagram of the surface acoustic wave resonator corresponding to different sound speed regions shown; Figure 5 A schematic cross-sectional structure diagram of a surface acoustic wave resonator provided in some other embodiments of the present application; Figure 6 for Figure 5 A schematic diagram of the planar structure of the interdigital transducer of the surface acoustic wave resonator shown; Figure 7 for Figure 6 The phase velocity (sound speed)-position diagram of the surface acoustic wave resonator corresponding to different sound speed regions shown; Figure 8 A schematic diagram of the structure of a surface acoustic wave resonator provided in some embodiments of the present application; Fig. 9 A schematic diagram of the structure of a surface acoustic wave resonator provided in some other embodiments of the present application; Fig.10 A schematic cross-sectional structure diagram of a surface acoustic wave resonator provided in some other embodiments of the present application; Fig.11 for Figure 5 The surface acoustic wave resonator shown in Fig.10 Comparison of the admittance curves of the surface acoustic wave resonators shown; Fig.12 for Fig.10 A schematic diagram of the planar structure of the interdigital transducer of the surface acoustic wave resonator shown; Fig.13 for Fig.10 A schematic diagram of a cross-sectional structure of a surface acoustic wave resonator shown; Fig.14 A schematic cross-sectional structure diagram of a surface acoustic wave resonator provided in some other embodiments of the present application; Fig.15 for Fig.10 The phase velocity (sound speed)-position diagram of the surface acoustic wave resonator corresponding to different sound speed regions shown; Fig.16 A schematic cross-sectional structure diagram of a surface acoustic wave resonator provided in some other embodiments of the present application; Fig.17 for Fig.10 A schematic diagram of the preparation process of a substrate assembly of a surface acoustic wave resonator is shown; Fig.18A schematic cross-sectional structure diagram of a surface acoustic wave resonator provided in some other embodiments of the present application; Fig.19 for Fig.18 A schematic diagram of the preparation process of a substrate assembly of a surface acoustic wave resonator is shown; Fig. 20 A schematic cross-sectional structure diagram of a surface acoustic wave resonator provided in some other embodiments of the present application; Fig.21 Schematic diagram of the cross-sectional structure of a surface acoustic wave resonator provided in some other embodiments of the present application.

[0035] Reference numerals: 1000, electronic equipment; 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; 10. piezoelectric substrate; 11. preset surface; 20. interdigital transducer; 21. first bus bar; 22. second bus bar; 23. first interdigital electrode; 24. second interdigital electrode; 20a. first excitation section; 20b. first transition section; 20c. first reflection section; 30. base layer; 40. functional layer; 50. substrate assembly; 51. first piezoelectric layer; 52. non-piezoelectric layer; 521. first part; 522. second part; 53. second piezoelectric layer; 54. third piezoelectric layer; 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

[0036] 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 of the embodiments.

[0037] In the embodiments of the present application, the terms "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0038] In the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0039] In the description of the embodiments of the present application, "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present application generally indicates that the associated objects before and after are in an "or" relationship.

[0040] 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, which are used for relative description and clarification, and may change accordingly according to the change of the orientation of the components in the drawings.

[0041] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, "connected" can be detachably connected or non-detachably connected; it can be directly connected or indirectly connected through an intermediate medium. Among them, "fixed connection" means that the two are connected to each other and the relative position relationship after connection remains unchanged.

[0042] In the description of the embodiments of the present application, the terms "perpendicular" and "parallel" include the situations described and situations similar to the situations described, and the range of the similar situations is within the acceptable deviation range, wherein the acceptable deviation range is determined by a person of ordinary skill in the art taking into account the measurement being discussed and the errors associated with the measurement of a specific quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, wherein the acceptable deviation range of approximate parallelism can be, for example, a deviation within 5°, 8°, or 10°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, wherein the acceptable deviation range of approximate perpendicularity can also be, for example, a deviation within 5°, 8°, or 10°.

[0043] Quality factor Q: represents the energy utilization rate of the device, that is, the ratio of the total energy received by the device to the energy dissipated in one vibration cycle. In the design of the filter, the quality factor Q value of the resonator that constitutes the filter is an important parameter.

[0044] The embodiment of the present application provides an electronic device, which includes but is not limited to products such as a radio frequency front end, a filter amplifier module, and a wireless communication system of a base station, and may also include mobile phones, tablet computers (pads), smart wearable products (for example, smart watches, smart bracelets), virtual reality (VR) devices, augmented reality (AR), drones, and other terminal devices with communication functions. The embodiment of the present application does not impose any special restrictions on the specific form of the above electronic devices.

[0045] 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 frequency point of a specific frequency in a 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.

[0046] Specifically, in some embodiments, the electronic device 1000 performs communication through a signal transmission and reception system. The signal transmission and reception system of the electronic device 1000 may include a receiver, a transmitter, an antenna, and a baseband chip. The antenna is electrically connected to the receiver and the transmitter respectively to realize signal reception and transmission. At the same time, the receiver and the transmitter are electrically connected to the baseband chip respectively to realize signal decoding, modulation, demodulation and other processing functions.

[0047] 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 be sent to the transmitter. The transmitter converts the information data to be sent into electrical signals and transmits these electrical signals through the antenna.

[0048] In some embodiments, the filter 100a can be set in both the receiver and the transmitter, and the filter 100a can filter unnecessary or undesirable frequencies or noises. Exemplarily, the receiver may include the filter 100a and a low noise amplifier, and the filter 100a can filter the noise of the low noise amplifier. The transmitter may include the filter 100a and a power amplifier, and the filter 100a can effectively filter the specific frequency point amplified by the power amplifier or the frequency outside the frequency point.

[0049] It is understandable that the above 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 also include other electronic components, which is not limited in this application.

[0050] 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, etc., or a combination of these structures.

[0051] In some embodiments, at least one of the multiple resonators included in the filter 100a can be a surface acoustic wave resonator 100 (surface acoustic wave, SAW). The main working principle of the surface acoustic wave resonator 100 is to use the piezoelectric characteristics of piezoelectricity, and use input and output transducers to convert the input signal of the radio wave into mechanical energy. After processing, the mechanical energy is converted into an electrical signal to filter unnecessary signals and noise and improve the quality of the signal reception.

[0052] See also Figure 2 , Figure 2 The cross-sectional structure diagram of the surface acoustic wave resonator 100 provided in some embodiments of the present application, the surface acoustic wave resonator 100 includes a piezoelectric substrate 10 and an interdigital transducer 20, wherein the piezoelectric substrate 10 is plate-shaped, and the interdigital transducer 20 and the piezoelectric substrate 10 are stacked along the first direction L1. That is, the interdigital transducer 20 is arranged on a preset surface 11 on one side of the thickness direction of the piezoelectric substrate 10. When receiving an electrical signal, the interdigital transducer 20 drives the piezoelectric substrate 10 to vibrate to generate a surface acoustic wave, which is transmitted along the preset surface 11, thereby converting the electrical signal into a mechanical vibration signal.

[0053] The present embodiment does not limit the material of the piezoelectric substrate 10, as long as the piezoelectric substrate 10 can vibrate under the drive of the interdigital transducer 20 to generate surface acoustic waves. Exemplarily, the material of the piezoelectric substrate 10 may include: piezoelectric crystals with specific crystal orientations, such as lithium niobate (LiNbO3), lithium tantalate (LiTaO3), quartz (Quartz), etc.; piezoelectric films, such as aluminum nitride (AlN), scandium-doped aluminum nitride (AlScN), etc.; piezoelectric ceramics, such as lead niobate (PbNb2O6), lead zirconate titanate (PZT), etc. In some embodiments, please refer to Figure 2The surface acoustic wave 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 away from the IDT 20, and the functional layer 40 is disposed on a side of the IDT 20 away from the piezoelectric substrate 10. That is, the surface acoustic wave 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 sequentially stacked along the first direction L1.

[0054] The base layer 30 is arranged at the bottom to serve as a substrate for other layers, and to carry and support other hierarchical 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 form a temperature compensation function for temperature compensation of the surface acoustic wave resonator 100. In this case, the surface acoustic wave resonator 100 is a temperature compensation surface acoustic wave device (Temperature Compensation Surface Acoustic Wave, TC-SAW). The functional layer 40 can form a passivation function for protection. In this case, the surface acoustic wave resonator 100 is a thin film surface acoustic wave device (thin film surface acoustic wave, TF-SAW).

[0055] In other embodiments, the surface acoustic wave device may also form a standard surface acoustic wave device (Standard Surface Acoustic Wave, STD-SAW), which is not limited in the present application.

[0056] The interdigital transducer 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 shown in the figure, 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 preset surface 11 and are arranged at intervals along the second direction L2, and the plurality of first interdigital electrodes 23 and the plurality of second interdigital electrodes 24 are both attached to the preset surface 11, and the first interdigital electrodes 23 and the second interdigital electrodes 24 are arranged alternately and in parallel along the third direction L3. In this way, a second interdigital electrode 24 is arranged between two adjacent first interdigital electrodes 23, and a first interdigital electrode 23 is arranged 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 are located between the first bus bar 21 and the second bus bar 22, and the first interdigital electrode 23 is connected to the first bus bar 21, and the second interdigital electrode 24 is 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.

[0057] During operation, the first interdigital electrodes 23 can be powered by the first bus bar 21, and the second interdigital electrodes 24 can be powered by the second bus bar 22, so that the piezoelectric substrate 10 vibrates to generate surface acoustic waves, which are transmitted near the preset surface 11 in a direction parallel to the preset surface 11. In some embodiments, the surface acoustic waves can be transmitted along the third direction L3. In other embodiments, the surface acoustic waves can also be propagated in a manner that most of them are transmitted along the third direction L3, and a small part is transmitted along other directions.

[0058] It is worth noting that this example does not limit the structure of the IDT 20 , and 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. In some embodiments, please refer to Figure 2 and Figure 3 The surface acoustic wave resonator 100 includes a first acoustic velocity zone A1, a fourth acoustic velocity zone A4 and a fifth acoustic velocity zone A5. The first acoustic velocity zone A1 is a region where the first interdigital electrode 23, the second interdigital electrode 24 and the piezoelectric substrate 10 are relatively stacked. The fourth acoustic velocity zone A4 is located on both sides of the first acoustic velocity zone A1 in the second direction L2. Only the region where the first interdigital electrode 23 or the second interdigital electrode 24 and the piezoelectric substrate 10 are relatively stacked forms the fourth acoustic velocity zone A4. The region where the first bus bar 21, the second bus bar 22 and the piezoelectric substrate 10 are relatively stacked forms the fifth acoustic velocity zone A5. Please refer to Figure 4 , Figure 4for 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.

[0059] In some embodiments, a surface acoustic wave interference phenomenon may occur between the first sound velocity zone A1 and the fourth sound velocity zone A4, which is specifically manifested in that the surface acoustic wave can be easily transmitted from the low sound velocity zone (a1) to the high sound velocity zone (a4). At this time, a large amount of the surface acoustic wave excited by the first sound velocity zone A1 is transmitted to the fourth sound velocity zone A4.

[0060] 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 the surface acoustic wave to enter the low sound velocity zone (a5) from the high sound velocity zone (a4). Most of the 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 a small part of the surface acoustic waves enters the fourth sound velocity zone A4. In this way, a large part of the surface acoustic waves in the first sound velocity zone A1 enters the fourth sound velocity zone A4, while this part of the surface acoustic waves enters the fourth sound velocity zone A4 less, that is, this part of the surface acoustic waves is constrained to oscillate in the fourth sound velocity zone A4, and the total amount of the surface acoustic waves in the fourth sound velocity zone A4 / the total amount of the surface acoustic waves in the first sound velocity zone A1 is large. In this way, Figures 2 to 4 The surface acoustic wave resonator 100 of the illustrated embodiment exhibits a high number of transverse mode spurious waves.

[0061] In order to reduce the transverse mode noise of the SAW resonator 100, please 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 planar structure diagram of the interdigital transducer 20 of the surface acoustic wave resonator 100 is shown in FIG. Figure 3 One difference between the illustrated embodiment is that the surface acoustic wave resonator 100 of the illustrated embodiment of the present application further includes a third sound velocity region A3 , and the third sound velocity region A3 is located between the first sound velocity region A1 and the fourth sound velocity region A4 .

[0062] 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 interdigitated electrode 23 shown in FIG. 1 includes a first excitation segment 20a located in the first sound velocity zone A1 and a first reflection segment 20c located in the third sound velocity zone A3. 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 (see FIG. Figure 5). In this way, the third sound velocity area A3 forms a reflection structure of the first sound velocity area A1.

[0063] Please refer to Figure 5 and Figure 7 , Figure 7 for Figure 6 The phase velocity (sound speed)-position diagram of the surface acoustic wave resonator 100 shown corresponds to different sound speed 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 speed of the third sound speed zone A3 is different from the sound speed of the first sound speed zone A1. At this time, the sound speed of the third sound speed zone A3 is a3, and a3 is smaller than a1. Due to the thickening of the first reflection section 20c, the third sound speed zone A3 and the first sound speed zone A1 where the first excitation section 20a is located do not interfere with each other. In this way, the third sound speed zone A3 forms a strong reflection zone, and more surface acoustic waves in the first sound speed zone A1 are reflected back to the first sound speed zone A1 by the third sound speed zone A3, and less enter the fourth sound speed zone A4 and the fifth sound speed zone A5. The total amount of surface acoustic waves in the fourth sound speed zone A4 / the total amount of surface acoustic waves in the first sound speed zone A1 is small, so that Figures 5 to 7 The surface acoustic wave resonator 100 of the illustrated embodiment exhibits relatively weak transverse mode spurious waves.

[0064] However, since the first reflection section 20c of the third sound velocity zone A3 itself can excite the piezoelectric substrate 10 below to generate surface acoustic waves, the surface acoustic waves excited by the third sound velocity zone A3 can be transmitted to the fourth sound velocity zone A4 to a large extent, and the surface acoustic waves of the fourth sound velocity zone A4 will be reflected back to the fourth sound velocity zone A4 by the fifth sound velocity zone A5, so that the surface acoustic wave energy of the fourth sound velocity zone A4 is still large, that is, the surface acoustic wave resonator 100 in the embodiment of the present application still has transverse mode clutter. It can be understood that when the width of the third sound velocity zone A3 in the second direction L2 is larger, the surface acoustic wave excited by it is larger, and the more transverse mode clutter is.

[0065] In some other embodiments, see Figure 8 , Figure 8 A schematic diagram of the structure 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 diagram of a cross-sectional structure of the surface acoustic wave resonator 100. Figure 8 (c) in the equation is Figure 8 Phase velocity (sound velocity)-position diagram of the surface acoustic wave resonator in (b) corresponding to different sound velocity zones. In this embodiment, by providing a material D with a high-density property in the functional layer 40 in the third sound velocity zone A3, wherein the material D with a high-density property is greater than the density of the material used for the piezoelectric substrate 10, the transverse mode clutter can be weakened.

[0066] See also Fig. 9 , Fig. 9 The schematic diagram of the structure of the surface acoustic wave resonator 100 provided in some other embodiments of the present application, wherein Fig. 9 (a) is a schematic diagram of the planar structure of the interdigital transducer 20 of the surface acoustic wave resonator 100. Fig. 9 (b) is a schematic diagram of a cross-sectional structure of the surface acoustic wave resonator 100. Fig. 9 (c) in the equation is Fig. 9 Phase velocity (sound speed)-position diagram of the surface acoustic wave resonator in (b) corresponding to different sound speed zones. In this embodiment, the reduction of transverse mode clutter is achieved by increasing the area occupied by the first reflection section 20c in the third sound speed zone A3 on the preset surface 11 (that is, the ratio of the orthographic projection surface of the first reflection section 20c on the preset surface 11 to the total orthographic projection area of ​​the interdigital transducer 20 on the preset surface 11).

[0067] and Figures 5 to 7 The same thing about the embodiments shown is that Figure 8 and Fig. 9 The third sound velocity zone A3 of the embodiment shown can generate surface acoustic waves to be transmitted to the fourth sound velocity zone A4, resulting in the surface acoustic wave energy of the fourth sound velocity zone A4 being still relatively large, and the transverse mode clutter phenomenon is still not solved. 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 appear the same as above. Figures 5 to 7 Same problem.

[0068] Based on this, in order to effectively suppress the transverse mode clutter phenomenon, please refer to Fig.10 , Fig.10 Schematic diagram of the cross-sectional structure of the surface acoustic wave resonator 100 provided in some other embodiments of the present application, Figure 5 to Figure 6 The same as the embodiment shown is that the base layer 30 and the functional layer 40 of the embodiment shown in the present application are the same as those of the above embodiment. Figure 5 to Figure 6 One difference between the illustrated embodiment is that the present application changes the piezoelectric substrate 10 into 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.

[0069] Specifically, the surface acoustic wave resonator 100 includes a substrate assembly 50 and an IDT 20 stacked along a first direction L1, and one side of the substrate assembly 50 is formed with 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, and 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.

[0070] The interdigital transducer 20 has a first excitation segment 20a and a first reflection segment 20c. The first excitation segment 20a and the first piezoelectric layer 51 are opposite in the first direction L1 for exciting surface acoustic waves. 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 to generate surface acoustic waves. The first reflection segment 20c and the non-piezoelectric layer 52 are opposite in the first direction L1 for reflecting surface acoustic waves, that is, the surface acoustic wave can be transmitted from one side of the first excitation segment 20a to the first reflection segment 20c, and reflected by the first reflection segment 20c to the first excitation segment 20a.

[0071] It can be understood that the non-piezoelectric layer 52 is located at the periphery of the first piezoelectric layer 51. The non-piezoelectric layer 52 may surround the first piezoelectric layer 51, and the non-piezoelectric layer 52 is located around 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, Fig.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.

[0072] 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 all falls 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 all falls 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 substrate assembly 50 below to generate surface acoustic waves.

[0073] In this way, the surface acoustic wave excited in the area where the first excitation segment 20a is located is reflected back to the area where the first excitation segment 20a is located in large quantities, and will not be transmitted to other areas. At the same time, the area where the first reflection segment 20c is located itself will not excite the surface acoustic wave, 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 segment 20c itself generates surface acoustic waves and causes the existence of transverse mode noise. At the same time, it can also reflect the surface acoustic waves transmitted from the first excitation segment 20a through the first reflection segment 20c, thereby effectively suppressing the generation of transverse mode noise and achieving the effect of mainly exciting the transverse mode.

[0074] See also Fig.11 , Fig.11 for Figure 5 The surface acoustic wave resonator 100 is Fig.10 The admittance curve comparison diagram of the surface acoustic wave resonator 100 shown in the figure, the horizontal axis of the admittance curve is frequency (Frequency), the unit is megahertz (MHz), and the vertical axis represents admittance (Admittance), with Siemens (S) as the unit. Admittance is a measure of the ability of a circuit or system to respond to alternating current. It is the reciprocal of impedance (Impedance). The height of the vertical axis can represent the quality factor (Q value). in, Fig.11 (a) in the equation is Figure 5 The admittance curve of the surface acoustic wave resonator 100 is shown in FIG. Fig.11 (b) in the equation is Fig.10 The admittance curve of the surface acoustic wave resonator 100 is shown in FIG. Fig.11 As can be seen from (a) in the figure, 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. Fig.11 As can be seen from (b), Fig.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, Fig.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 .

[0075] See also Fig.12 , Fig.12 for Fig.10 The planar structural schematic diagram of the interdigital transducer 20 of the surface acoustic wave resonator 100 shown in the figure 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.

[0076] In some embodiments, see Fig.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 Fig.13 , Fig.13 for Fig.10 A schematic cross-sectional structure diagram of the surface acoustic wave resonator 100 is shown, and the first excitation segment 20a and the first reflection segment 20c may also be located on the second interdigital electrode 24, and the present application does not limit this. Exemplarily, the first excitation segment 20a and the first reflection segment 20c may be arranged on the first interdigital electrode 23, and the second excitation segment and the second reflection segment may be arranged on the second interdigital electrode 24, wherein the arrangement of the second excitation segment may refer to the arrangement of the first excitation segment 20a, and the arrangement of the second reflection segment may refer to the arrangement of the first reflection segment 20c. In the following, for the sake of convenience, the first interdigital electrode 23 is taken as an example for description.

[0077] 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, and 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.

[0078] 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 mentioned above, and the surface acoustic wave excited by the first sound velocity zone A1 can be transmitted to the outside, that is, to one side of the third sound velocity zone A3, and is 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 sound velocity region A3 in the above text is the same.

[0079] In this way, by introducing the non-piezoelectric layer 52 in the third sound velocity zone A3, there will be no acoustic interference between the first sound velocity zone A1 and the third sound velocity zone A3, that is, the surface acoustic wave 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 the surface acoustic wave, so that the surface acoustic wave 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 and reduces the generation of transverse mode noise.

[0080] In some embodiments, in order to avoid the transmission of surface acoustic waves from the first sound velocity zone A1 to the third sound velocity zone A3, it is necessary to set the sound velocity of the surface acoustic wave in the first reflection section 20c to be unequal to the sound velocity 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 the surface acoustic wave. In this way, it is possible to avoid interference between the third sound velocity zone A3 and the first sound velocity zone A1, which is specifically manifested in the discontinuity of the transmission of the surface acoustic wave between the first sound velocity zone A1 and the third sound velocity zone A3, and the third sound velocity zone A3 forms a reflection structure of the first sound velocity zone A1, thereby achieving effective reflection of the surface acoustic wave of the first sound velocity zone A1.

[0081] 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, which is not limited or listed in the present application.

[0082] Generally, the sound speed in different sound speed zones depends on the material properties, materials and thickness of each layer in the area. In some embodiments, the thickness of the first reflection segment 20c and the first excitation segment 20a in the first direction L1 can be set to be different, so that the sound speeds of the first sound speed zone A1 and the third sound speed zone A3 are different, which is simple to manufacture and low in cost.

[0083] For example, see Fig.10 , at this time, 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. Fig.14 , Fig.14 The cross-sectional structure diagram of the surface acoustic wave resonator 100 provided in some 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 make any limitation thereto.

[0084] 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 speed of the first sound speed zone A1 is greater than the sound speed of the second sound speed 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 speed of the first sound speed zone A1 is less than the sound speed of the second sound speed 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 to each other and do not excite surface acoustic waves, as long as the sound speed of the surface acoustic wave in the first reflection segment 20c is not equal to the sound speed in the first excitation segment 20a, the third sound speed zone A3 can reflect the surface acoustic wave transmitted from the first sound speed zone A1.

[0085] In some embodiments, please refer to Fig.10 , Figure 12 to Figure 14 The interdigital transducer 20 further includes a first transition section 20b, which is located between the first excitation section 20a and the first reflection section 20c, and the first transition section 20b is directly opposite to the non-piezoelectric layer 52 in the first direction L1. At this time, the first excitation section 20a, the first transition section 20b and the first reflection section 20c can be arranged in sequence on the first interdigital electrode 23 along the second direction L2. In addition, the areas where the first reflection section 20c and the first transition section 20b are located do not excite surface acoustic waves.

[0086] 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 to 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 to the first piezoelectric layer 51, thereby reducing the preparation accuracy of the boundary of the non-piezoelectric layer 52, and 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 process preparation.

[0087] Furthermore, by disposing the first transition section 20b, the propagation path of the surface acoustic wave of the first excitation section 20a is extended, and the generation of transverse mode clutter can also be effectively suppressed.

[0088] In some embodiments, the surface acoustic wave resonator 100 further includes a second sound velocity zone A2, the second sound velocity zone A2 is located on one side of the first sound velocity zone A1 in the second direction L2, and the third sound velocity zone A3 is located on the side of the second sound velocity zone A2 away from the first sound velocity zone A1 in the second direction L2, forming the first sound velocity zone A1, the second sound velocity zone A2, and the third sound velocity zone A3 are sequentially arranged along the second direction L2. The first transition section 20b and a portion of the non-piezoelectric layer 52 are located in the second sound velocity zone A2, and the first reflection section 20c and another portion of the non-piezoelectric layer 52 are located in the third sound velocity zone A3.

[0089] See also Fig.14 , the non-piezoelectric layer 52 is defined to include a first portion 521 and a second portion 522, the first portion 521 is directly opposite to the first transition section 20b, and the second portion 522 is directly opposite to the first reflection section 20c, at this time, the first portion 521 forms the inner boundary of the second portion 522, when the non-piezoelectric layer 52 is prepared for the second portion 522, the existence of the first portion 521 reduces the difficulty of preparing the non-piezoelectric layer 52. At the same time, since both the second portion 522 and the first portion 521 are non-piezoelectric layers 52, it is ensured that no surface acoustic waves are excited in the second sound velocity zone A2 and the third sound velocity zone A3.

[0090] In some embodiments, in order to realize the reciprocating transmission of the surface acoustic wave between the first sound velocity zone A1 and the second sound velocity zone A2, the sound velocity of the surface acoustic wave in the first excitation section 20a is equal to the sound velocity of the surface acoustic wave in the first transition section 20b, so that the continuous transmission of the surface acoustic wave is formed between the first sound velocity zone A1 and the second sound velocity zone A2. Exemplarily, in order to realize the same sound velocity of the surface acoustic wave in the first sound velocity zone A1 and the second sound velocity zone A2, the thickness of the first excitation section 20a in the first direction L1 can be made equal to the thickness of the first transition section 20b in the first direction L1, so that the continuous reciprocating transmission of the surface acoustic wave is formed between the first sound velocity zone A1 and the second sound velocity zone A2.

[0091] exist Fig.10 , Figure 12 to Figure 14 In the illustrated embodiment, the second sound velocity zone A2 and the third sound velocity zone A3 each include two, 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, it can be configured so that each second sound velocity zone A2 includes a first transition section 20b and a first portion 521 of the non-piezoelectric layer 52, and each third sound velocity zone A3 includes a first reflection section 20c and a second portion 522 of the non-piezoelectric layer 52. In this way, the third sound velocity zone A3 can reflect the surface acoustic wave from the first sound velocity zone A1 on opposite sides in the second direction L2 to improve the main mode excitation effect.

[0092] 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, and the present application does not make any limitation thereto.

[0093] In some embodiments, the first part 521 of the non-piezoelectric layer 52 and the second part 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 formed in one-time processing, thereby simplifying the preparation process of the substrate assembly 50.

[0094] In some embodiments, please refer to Fig.10 , Figure 12 to Figure 14The surface acoustic wave resonator 100 also includes a fourth sound velocity zone A4 and a fifth sound velocity zone A5. The fourth sound velocity zone A4 is located on both sides of the third sound velocity zone A3 in the second direction L2, and the fifth sound velocity zone A5 is located on both sides of the fourth sound velocity zone A4 in the second direction L2, forming an arrangement in which the fifth sound velocity zone A5, the fourth sound velocity zone A4, the third sound velocity zone A3, the second sound velocity zone A2, the first sound velocity zone A1, the second sound velocity zone A2, the third sound velocity zone A3, the fourth sound velocity zone A4, and the fifth sound velocity zone A5 are arranged in sequence in the second direction L2.

[0095] See also Fig.15 , Fig.15 for Fig.10 The phase velocity (sound speed)-position diagram of the surface acoustic wave resonator 100 shown corresponds to different sound speed zones. At this time, the sound speed of the first sound speed zone A1 is a1, the sound speed of the second sound speed zone A2 is a2, the sound speed of the third sound speed zone A3 is a3, 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. As can be seen from the above, in some embodiments, a1 is equal to a2, and a3 is less than a2. And because the metallization ratio of the fourth sound speed zone A4 (that is, the projection area of ​​the interdigital transducer 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, therefore, 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, therefore, a5 is less than a1.

[0096] 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 be made of lithium niobate or lithium tantalate, and different processes can be 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 to ensure that the sound speeds of the first sound velocity zone A1 and the second sound velocity zone A2 are the same, so that the surface acoustic wave can be transmitted back and forth between the first sound velocity zone A1 and the second sound velocity zone A2.

[0097] 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 area A1 and the second sound speed area A2 are the same.

[0098] In other embodiments, the sound velocities in the first sound velocity zone A1 and the second sound velocity zone A2 may be the same by setting other parameters of the first piezoelectric layer 51 and the non-piezoelectric layer 52. This application does not limit this.

[0099] In some embodiments, see Fig.10 , Fig.14 and Fig.16 , Fig.16 The cross-sectional structure diagram of the surface acoustic wave resonator 100 provided for other embodiments of the present application, 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 position where the first piezoelectric layer 51 is provided is not provided with the non-piezoelectric layer 52, and the position where the non-piezoelectric layer 52 is provided is not provided with the first piezoelectric layer 51, and the first piezoelectric layer 51 and the non-piezoelectric layer 52 are not stacked in the first direction L1. In this way, when preparing the substrate assembly 50, the preparation process can be simplified.

[0100] Specifically, Fig.10 The manufacturing process of the surface acoustic wave resonator 100 shown in FIG. Fig.17 , Fig.17 for Fig.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: Step S1: providing a piezoelectric material layer 60; Step S2: etching the piezoelectric material layer 60 to form a through hole 61 by etching or other processes; Step S3: coating the non-piezoelectric material layer 70 on one side of the piezoelectric material layer 60 by a coating process, wherein the portion of the non-piezoelectric material layer 70 that enters the through hole 61 forms the non-piezoelectric layer 52, and the portion falls on the surface of one side of the piezoelectric material layer 60 to form redundancy; Step S4: removing the redundant non-piezoelectric material layer 70 on one side of the surface of the piezoelectric material layer 60 through a cleaning process, thereby obtaining a completed substrate assembly 50 .

[0101] 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, Fig.14 and Fig.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 may also be embedded, that is, Fig.10 In 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 may be different parts of the integrally formed piezoelectric material layer 60, that is, the material and thickness of the second piezoelectric layer 53 may be equal to those of the first piezoelectric layer 51. Through the formation of the through hole 61, the parts on both sides of the through hole 61 form the first piezoelectric layer 51 and the second piezoelectric layer 53 respectively. In this way, when the non-piezoelectric layer 52 is formed in the through hole 61, the second piezoelectric layer 53 is located at the periphery of the non-piezoelectric layer 52, and the non-piezoelectric layer 52 is located at the periphery of the first piezoelectric layer 51.

[0102] so, Fig.17 In the manufacturing process of the piezoelectric substrate 10 of the illustrated embodiment, only the hole 61 needs to be punched, and the drilling depth does not need to be considered, thereby simplifying the manufacturing of the surface acoustic wave resonator 100 and reducing the process precision requirements, reducing costs and improving economic benefits.

[0103] Understandably, in Fig.10 , Fig.14 and Fig.16 In the surface acoustic wave resonator 100 of the embodiment shown, there is only a non-piezoelectric layer 52 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 contain a non-piezoelectric layer 52 and a third piezoelectric layer 54 (see below). Fig.18 ) are superimposed 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.

[0104] For details, please refer to Fig.18 , Fig.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. Fig.18 In the embodiment, the substrate assembly 50 further includes a third piezoelectric layer 54, which is located at the periphery of the first piezoelectric layer 51, and the non-piezoelectric layer 52 and at least part of the third piezoelectric layer 54 are stacked along the first direction L1, and the non-piezoelectric layer 52 is located between the interdigital transducer 20 and the third piezoelectric layer 54. In this way, a stacking mode in which the first reflection section 20c, the non-piezoelectric layer 52 and the third piezoelectric layer 54 are sequentially arranged is formed in the third sound velocity area A3, so as to ensure that the first reflection section 20c does not excite surface acoustic waves on the piezoelectric substrate 10.

[0105] Understandable, such as Fig.18 In the embodiment shown, the third piezoelectric layer 54 is disposed 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. Fig.19 , Fig.19 for Fig.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: Step S1: providing a piezoelectric material layer 60; 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; Step S3: coating the non-piezoelectric material layer 70 on one side of the piezoelectric material layer 60 by a coating process, wherein the portion of the non-piezoelectric material layer 70 that enters the empty groove 62 forms the non-piezoelectric layer 52, and the portion falls on the surface of one side of the piezoelectric material layer 60 to form redundancy; 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 .

[0106] In the above Fig.19 In the illustrated embodiment, 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.

[0107] 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, Fig. 20 and Fig.21 , Fig. 20 is a schematic cross-sectional structure diagram of a surface acoustic wave resonator 100 provided in some embodiments of the present application, Fig.21 The cross-sectional structure schematic 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 orthographic 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.

[0108] In some embodiments, see Fig.21 , in 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, and 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. Fig.10 A surface acoustic wave resonator 100 in the illustrated embodiment.

[0109] 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 the present application.

[0110] 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.

[0111] 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 it. 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 includes a first piezoelectric layer and a non-piezoelectric layer, wherein the non-piezoelectric layer is located at the periphery of the first piezoelectric layer; An interdigital transducer is stacked with the substrate assembly 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, the first reflection segment is 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.

2. The surface acoustic wave resonator according to claim 1, characterized in that: 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, characterized in that: 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, characterized in that: 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.

5. The surface acoustic wave resonator according to claim 4, characterized in that: The sound velocity of the surface acoustic wave in the first excitation section is equal to the sound velocity in the first transition section.

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

7. The surface acoustic wave resonator according to claim 5, characterized in that: The non-piezoelectric layer includes a first portion and a second portion, the first portion is directly opposite to the first transition section in the first direction, and the second portion is directly 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.

8. The surface acoustic wave resonator according to claim 4, characterized in that: The surface acoustic wave resonator has a first sound velocity region, a second sound velocity region, and a third sound velocity region, the second sound velocity region is located on one side of the first sound velocity region in the second direction, 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 velocity zone, the first transition segment and a portion of the non-piezoelectric layer are located in a second sound velocity zone, and the first reflection segment and another portion of the non-piezoelectric layer are located in a third sound velocity zone.

9. The surface acoustic wave resonator according to claim 8, 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.

10. The surface acoustic wave resonator according to claim 1, characterized in that: 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.

11. The surface acoustic wave resonator according to claim 1, characterized in that: In the first direction, the thickness of the non-piezoelectric layer is equal to the thickness of the first piezoelectric layer.

12. The surface acoustic wave resonator according to claim 11, characterized in that: The substrate assembly also includes a second piezoelectric layer located at an outer periphery of the non-piezoelectric layer.

13. The surface acoustic wave resonator according to claim 1, characterized in that: The substrate assembly further includes a third piezoelectric layer, wherein the third piezoelectric layer is located at 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.

14. The surface acoustic wave resonator according to claim 13, characterized in that: 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%.

15. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further comprises a base layer, the substrate assembly is arranged on the base layer, and the interdigital transducer is located on a side of the substrate assembly away from the base layer.

16. The surface acoustic wave resonator according to claim 1, characterized in that: The surface acoustic wave resonator further comprises a functional layer, and the functional layer is arranged on a side of the interdigital transducer facing away from the substrate assembly.

17. A filter, characterized in that: A surface acoustic wave resonator comprising any one of claims 1-16.

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

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