Surface acoustic wave resonator, filter and electronic equipment

Abstract

The invention discloses a surface acoustic wave resonator, a filter and electronic equipment, relates to the technical field of radio frequency, and aims to solve the problem that the displacement of high-order body wave stray is easily concentrated in a dielectric layer between a substrate and a piezoelectric layer, the surface acoustic wave resonator is characterized in that the dielectric layer comprises at least two low-sound-velocity first sub dielectric layers; a high-sound-velocity second sub-dielectric layer is inserted between two adjacent low-sound-velocity first sub-dielectric layers, continuity of sound velocity in the dielectric layers is destroyed, and interfaces of the first sub-dielectric layers and the second sub-dielectric layers can reflect high-order body wave spurious waves, so that generation and propagation of the high-order body wave spurious waves are weakened, and particularly, generation and propagation of the high-order body wave spurious waves are reduced. The interface between the second sub-dielectric layer and at least one adjacent first sub-dielectric layer is set to be an irregular interface, so that when the irregular interface between the first sub-dielectric layer and the second sub-dielectric layer reflects high-order body wave stray, the high-order body wave stray is further suppressed, and the performance of the surface acoustic wave resonator, the filter and the electronic equipment is improved.

Description

Technical Field

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

[0002] A surface acoustic wave (SAW) resonator is a device widely used in the radio frequency field, which combines low insertion loss and good suppression performance, and has a small volume at the same time. It mainly uses the piezoelectric effect to convert electrical energy and mechanical energy into each other, and is used to combine the gating characteristics for signal transmission.

[0003] There are many types of surface acoustic wave resonators. The thin-film surface acoustic wave (TC-SAW) resonator is a type of surface acoustic wave resonator structure widely used in recent years. As Figure 1 shown, the thin-film surface acoustic wave resonator includes a substrate 10, a piezoelectric layer 30 located on the substrate 10, and an interdigital transducer 40 located on the side of the piezoelectric layer 30 facing away from the substrate 10. And a dielectric layer 20 can be provided between the substrate 10 and the piezoelectric layer 30 to play a role such as temperature compensation.

[0004] However, in a surface acoustic wave resonator, higher-order modes are usually more easily excited, resulting in out-of-band spurs. Especially after adding a dielectric layer between the substrate and the piezoelectric layer, it will instead enhance the higher-order bulk wave spurs, affecting the performance of the surface acoustic wave resonator. Furthermore, a filter based on the surface acoustic wave resonator may respond to signals outside the passband, making it difficult to meet the requirements of modern mobile communication for high selectivity of the filter. Summary of the Invention

[0005] To solve the above technical problems, embodiments of the present application provide a surface acoustic wave resonator, a filter, and an electronic device to suppress higher-order bulk wave spurs in the surface acoustic wave resonator and improve the performance of the surface acoustic wave resonator, filter, and electronic device.

[0006] To achieve the above object, embodiments of the present application provide the following technical solutions:

[0007] In a first aspect, embodiments of the present application provide a surface acoustic wave resonator, including:

[0008] A substrate;

[0009] A dielectric layer located on one side of the substrate, the dielectric layer includes at least two first sub-dielectric layers stacked in a direction away from the substrate, and a second sub-dielectric layer is provided between adjacent two first sub-dielectric layers, and the interface between the second sub-dielectric layer and at least one adjacent first sub-dielectric layer is an irregular interface;

[0010] A piezoelectric layer located on the side of the dielectric layer facing away from the substrate, wherein the sound velocity of the first sub-dielectric layer is less than that of the piezoelectric layer, and the sound velocity of the second sub-dielectric layer is greater than that of the piezoelectric layer;

[0011] An interdigital transducer located on the side of the piezoelectric layer facing away from the substrate.

[0012] Optionally, the interfaces between the second sub-dielectric layer and the two adjacent first sub-dielectric layers are all irregular interfaces.

[0013] Optionally, the interdigital transducer includes a first bus bar and a second bus bar arranged opposite to each other, electrode fingers connected to the first bus bar, and electrode fingers connected to the second bus bar. The electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged in a first direction, and the electrode fingers extend in a second direction;

[0014] In a cross-section perpendicular to the second direction, the ratio RA1 of the cross-sectional area of the second sub-dielectric layer in the dielectric layer to the sum of the cross-sectional areas of all the first sub-dielectric layers satisfies: 4% ≤ RA1 ≤ 18%.

[0015] Optionally, the interdigital transducer includes a first bus bar and a second bus bar arranged opposite to each other, electrode fingers connected to the first bus bar, and electrode fingers connected to the second bus bar. The electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged in a first direction, and the electrode fingers extend in a second direction;

[0016] At least two second sub-dielectric layers are provided in the dielectric layer. In a cross-section perpendicular to the second direction, along the direction away from the substrate and towards the piezoelectric layer, the ratio RA1 of the cross-sectional area of each second sub-dielectric layer in the dielectric layer to the sum of the cross-sectional areas of all the first sub-dielectric layers gradually increases.

[0017] Optionally, the interdigital transducer includes a first bus bar and a second bus bar arranged opposite to each other, electrode fingers connected to the first bus bar, and electrode fingers connected to the second bus bar. The electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged in a first direction, and the electrode fingers extend in a second direction;

[0018] In a cross-section perpendicular to the second direction, along the direction away from the substrate and towards the piezoelectric layer, the ratio RA2 of the cross-sectional area of each first sub-dielectric layer in the dielectric layer to the sum of the cross-sectional areas of all the first sub-dielectric layers gradually decreases.

[0019] Optionally, the dielectric layer includes two layers of the first sub-dielectric layer and one layer of the second sub-dielectric layer between the two layers of the first sub-dielectric layer;

[0020] In a cross-section perpendicular to the second direction, the ratio RA21 of the cross-sectional area of one layer of the first sub-dielectric layer closer to the piezoelectric layer in the two layers of the first sub-dielectric layer of the dielectric layer to the sum of the cross-sectional areas of the two layers of the first sub-dielectric layer satisfies: 0 < RA21 < 50%.

[0021] Optionally, the first sub-dielectric layer is a silicon dioxide layer;

[0022] In the dielectric layer, the densities of the two layers of the first sub-dielectric layer adjacent to the second sub-dielectric layer are different.

[0023] Optionally, in the dielectric layer, along the direction away from the substrate and closer to the piezoelectric layer, the density of each first sub-dielectric layer gradually decreases;

[0024] Alternatively, in the dielectric layer, along the direction away from the substrate and closer to the piezoelectric layer, the density of the first sub-dielectric layer gradually increases.

[0025] Optionally, the dielectric layer further includes a third sub-dielectric layer between one layer of the first sub-dielectric layer closest to the piezoelectric layer and the piezoelectric layer, and the sound velocity of the third sub-dielectric layer is greater than the sound velocity of the piezoelectric layer.

[0026] Optionally, the material of the second sub-dielectric layer includes at least one of silicon nitride, aluminum nitride, and silicon oxynitride.

[0027] In a second aspect, an embodiment of the present application provides a filter, including any one of the above surface acoustic wave resonators.

[0028] In a third aspect, an embodiment of the present application provides an electronic device, including the above filter.

[0029] Compared with the prior art, the above technical solution has the following advantages:

[0030] The surface acoustic wave resonator provided by the embodiments of the present application includes a substrate, and a dielectric layer, a piezoelectric layer, and an interdigital transducer that are stacked on one side of the substrate in a direction away from the substrate. Among them, the dielectric layer includes at least two first sub-dielectric layers stacked in a direction away from the substrate. The sound velocity of the first sub-dielectric layer is less than that of the piezoelectric layer. These at least two first sub-dielectric layers can play a role in temperature compensation, and effectively isolate the substrate and the piezoelectric layer, ensuring excellent electrical characteristics and acoustic performance, etc. The inventor's research found that the displacement of high-order bulk wave spurs is easily concentrated in the dielectric layer between the substrate and the piezoelectric layer. In this way, adding a dielectric layer between the substrate and the piezoelectric layer will instead enhance the high-order bulk wave spurs. Based on this, a second sub-dielectric layer is provided between adjacent two first sub-dielectric layers. The sound velocity of the second sub-dielectric layer is greater than that of the piezoelectric layer. In this way, by inserting a high-sound-velocity second sub-dielectric layer between two adjacent low-sound-velocity first sub-dielectric layers, the continuity of the sound velocity in the dielectric layer is destroyed. Moreover, the interface between the first sub-dielectric layer and the second sub-dielectric layer can reflect high-order bulk wave spurs, thereby weakening the generation and propagation of high-order bulk wave spurs. In particular, the interface between the second sub-dielectric layer and at least one adjacent first sub-dielectric layer is set as an irregular interface. In this way, when the irregular interface between the first sub-dielectric layer and the second sub-dielectric layer reflects high-order bulk wave spurs, the high-order bulk wave spurs can be further suppressed. In addition, the low-sound-velocity first sub-dielectric layer and the high-sound-velocity second sub-dielectric layer form a sound velocity gradient, which can better confine the energy in the piezoelectric layer. The above structural design can overall improve the performance of surface acoustic wave resonators, filters, and electronic devices.

[0031] Other objects and advantages of the present application will be described in detail in the following embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a cross-sectional structure schematic diagram of a conventional surface acoustic wave resonator;

[0034] Figure 2 It is a cross-sectional structure schematic diagram of a surface acoustic wave resonator provided by the embodiments of the present application;

[0035] Figure 3 For Figure 1 the vibration mode diagram of the high-order bulk wave spur A in the surface acoustic wave resonator shown;

[0036] Figure 4 For Figure 1 the simulation result diagrams of two surface acoustic wave resonators shown in Figure 2 without setting the second sub-medium layer 22 in the medium layer 20 (i.e., the prior art) and Figure 2 the simulation result diagrams of two surface acoustic wave resonators shown in with the second sub-medium layer 22 set in the medium layer 20 (i.e., the present application);

[0037] Figure 5 is a schematic cross-sectional structure diagram of another surface acoustic wave resonator provided by an embodiment of the present application;

[0038] Figure 6 is a schematic cross-sectional structure diagram of yet another surface acoustic wave resonator provided by an embodiment of the present application;

[0039] Figure 7 is a top view schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present application;

[0040] Figure 8 is a simulation result diagram of a surface acoustic wave resonator with a second sub-medium layer 22 of different equivalent thicknesses inserted in the medium layer 20;

[0041] Figure 9 is a schematic cross-sectional structure diagram of yet another surface acoustic wave resonator provided by an embodiment of the present application;

[0042] Figure 10 is a simulation result diagram of a surface acoustic wave resonator with a layer of second sub-medium layer 22 inserted at different positions in the medium layer 20;

[0043] Figure 11 is a schematic cross-sectional structure diagram of yet another surface acoustic wave resonator provided by an embodiment of the present application;

[0044] Figure 12 is a schematic cross-sectional structure diagram of yet another surface acoustic wave resonator provided by an embodiment of the present application.

[0045] Reference numerals:

[0046] 10 - substrate; 20 - medium layer; 21 - first sub-medium layer; 22 - second sub-medium layer; 23 - third sub-medium layer; 30 - piezoelectric layer; 40 - interdigital transducer; 41 - first bus bar; 42 - second bus bar; 431 - electrode finger connected to the first bus bar; 432 - electrode finger connected to the second bus bar; X - first direction; Y - second direction; Z - third direction; A - higher-order bulk wave spurious; BB' - cross-section perpendicular to the second direction. Detailed implementation manners

[0047] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0048] The terms "first", "second", etc. in the description and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing when describing objects with the same attributes in the embodiments of the present application. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product or device including a series of units does not necessarily have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products or devices.

[0049] Secondly, the present application will be described in detail in conjunction with the schematic diagrams. When describing the embodiments of the present application in detail, for the convenience of explanation, the drawings showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples, which should not limit the protection scope of the present application here. In addition, in actual production, three-dimensional spatial dimensions including length, width and depth should be included.

[0050] As described in the background art section, in a surface acoustic wave resonator, higher-order modes are usually more easily excited, thus generating out-of-band spurs. Especially after adding a dielectric layer between the substrate and the piezoelectric layer, it will instead enhance the higher-order bulk wave spurs, affecting the performance of the surface acoustic wave resonator. Furthermore, a filter built based on the surface acoustic wave resonator may respond to signals outside the passband, making it difficult to meet the requirements of high selectivity of filters for modern mobile communications.

[0051] In view of this, the embodiments of the present application provide a surface acoustic wave resonator. Figure 2 The cross-sectional structural schematic diagram of a surface acoustic wave resonator provided by the embodiments of the present application is shown, as Figure 2As shown, the surface acoustic wave resonator includes a substrate 10, a dielectric layer 20 on one side of the substrate 10, a piezoelectric layer 30 on the side of the dielectric layer 20 facing away from the substrate 10, and an interdigital transducer 40 on the side of the piezoelectric layer 30 facing away from the substrate 10; wherein, the dielectric layer 20 includes at least two first sub-dielectric layers 21 stacked in a direction away from the substrate 10, and a second sub-dielectric layer 22 is provided between adjacent two first sub-dielectric layers 21. The interface between the second sub-dielectric layer 22 and at least one adjacent first sub-dielectric layer 21 is an irregular interface, and the sound velocity of the first sub-dielectric layer 21 is less than that of the piezoelectric layer 30, and the sound velocity of the second sub-dielectric layer 22 is greater than that of the piezoelectric layer 30.

[0052] Optionally, the first sub-dielectric layer 21 may be a silicon dioxide (SiO2) layer. Taking the first sub-dielectric layer 21 as a silicon dioxide layer as an example, the functions of at least two first sub-dielectric layers 21 located between the substrate 10 and the piezoelectric layer 30 will be described below.

[0053] First, at least two first sub-dielectric layers 21 located between the substrate 10 and the piezoelectric layer 30 have the function of temperature compensation.

[0054] The temperature coefficient of the material of the piezoelectric layer 30, such as lithium niobate LiNbO3 or lithium tantalate LiTaO3, is positive and relatively large, resulting in a significant change in the resonant frequency with temperature. The temperature coefficient of the material of the first sub-dielectric layer 21 (silicon dioxide SiO2) is usually negative, that is, the frequency temperature coefficient of the first sub-dielectric layer 21 is opposite to the polarity of the frequency temperature coefficient of the piezoelectric layer 30, which can form a complement with the positive temperature coefficient of the piezoelectric layer 30, thereby offsetting the frequency drift caused by temperature changes and improving the temperature stability of the resonator.

[0055] Second, at least two first sub-dielectric layers 21 located between the substrate 10 and the piezoelectric layer 30 have the function of electrical isolation.

[0056] The excellent insulation characteristics of the first sub-dielectric layer 21 (silicon dioxide layer) can effectively isolate the piezoelectric layer 30 and the substrate 10, avoiding parasitic capacitance or leakage current between the piezoelectric layer 30 and the substrate 10, and ensuring excellent electrical and acoustic properties.

[0057] Third, at least two first sub-dielectric layers 21 located between the substrate 10 and the piezoelectric layer 30 have the function of acoustic wave energy confinement.

[0058] The sound velocity of the first sub-dielectric layer 21 (silicon dioxide layer) is less than that of the piezoelectric layer 30. Thus, when the acoustic wave propagates from the piezoelectric layer 30 to the first sub-dielectric layer 21, the difference in sound velocity can cause the energy to be reflected back to the piezoelectric layer 30, thereby reducing the leakage of acoustic wave energy to the substrate 10, further improving the Q value of the resonator, and reducing the insertion loss, etc.

[0059] Fourth, at least two first sub-dielectric layers 21 located between the substrate 10 and the piezoelectric layer 30 have the function of mechanical stress buffering.

[0060] The substrate 10 (such as a silicon substrate) and the piezoelectric layer 30 have a large difference in thermal expansion coefficient. Interface stress may be generated during temperature changes, resulting in device cracking or delamination. The thermal expansion coefficient of silicon dioxide SiO2 is between that of silicon and the piezoelectric material. Therefore, the first sub-dielectric layer 21 (silicon dioxide layer) can act as a buffer layer to reduce thermal stress.

[0061] It can be seen from this that setting the first sub-dielectric layer 21 between the substrate 10 and the piezoelectric layer 30 has the advantage of improving the performance of the surface acoustic wave resonator in many aspects. However, the inventor's research found that if the entire dielectric layer 20 is a silicon dioxide layer, then the displacement of the higher-order bulk wave spurious is likely to be concentrated in the dielectric layer 20 between the substrate 10 and the piezoelectric layer 30. In this way, adding the dielectric layer 20 between the substrate 10 and the piezoelectric layer 30 will instead enhance the higher-order bulk wave spurious.

[0062] Specifically, Figure 3 shows Figure 1 the vibration mode diagram of the higher-order bulk wave spurious A in the shown surface acoustic wave resonator (i.e., a silicon dioxide layer is set as the dielectric layer 20 between the substrate 10 and the piezoelectric layer 30). Among them, the higher-order bulk wave spurious A is also called high-frequency spurious or high-frequency bulk wave parasitic spurious. The displacement of the higher-order bulk wave spurious A includes a displacement component along the first direction X and a displacement component along the third direction Z. The higher-order bulk wave spurious A is a coupled wave of a spurious wave vibrating along the first direction X and a spurious wave vibrating along the third direction Z. The third direction Z is the stacking direction of the dielectric layer 20 and the piezoelectric layer 30, and the first direction X is the arrangement direction of the electrode fingers in the interdigital transducer 40. From Figure 3 it can be seen that the displacement of the higher-order bulk wave spurious A is concentrated in the dielectric layer 20.

[0063] Based on this, in the surface acoustic wave resonator provided by the embodiments of the present application, the dielectric layer 20 is set to include at least two first sub-dielectric layers 21 stacked in a direction away from the substrate 10, and a second sub-dielectric layer 22 is disposed between two adjacent first sub-dielectric layers 21. The sound velocity of the second sub-dielectric layer 22 is greater than that of the piezoelectric layer 30. Thus, a layer of high-sound-velocity second sub-dielectric layer 22 is inserted between two adjacent low-sound-velocity first sub-dielectric layers 21 to break the continuity of the sound velocity in the dielectric layer 20. Moreover, the interface between the first sub-dielectric layer 21 and the second sub-dielectric layer 22 can reflect the higher-order bulk wave spurious A, thereby weakening the generation and propagation of the higher-order bulk wave spurious A. In particular, the interface between the second sub-dielectric layer 22 and at least one adjacent first sub-dielectric layer 21 is set as an irregular interface. Thus, when the irregular interface between the first sub-dielectric layer 21 and the second sub-dielectric layer 22 reflects the higher-order bulk wave spurious A, the higher-order bulk wave spurious A can be further suppressed. In addition, the low-sound-velocity first sub-dielectric layer 21 and the high-sound-velocity second sub-dielectric layer 22 form a sound velocity gradient, which can better confine the energy in the piezoelectric layer 30. The above structural design can overall improve the performance of the surface acoustic wave resonator.

[0064] It can be understood that the interface between the second sub-dielectric layer 22 and the adjacent first sub-dielectric layer 21 being an irregular interface means that the interface between the second sub-dielectric layer 22 and the adjacent first sub-dielectric layer 21 is an uneven and non-periodic interface. Such an irregular interface can scatter the higher-order bulk wave spurious A to further suppress the higher-order bulk wave spurious A. However, the present application does not limit the specific structure of the irregular interface between the second sub-dielectric layer 22 and the adjacent first sub-dielectric layer 21.

[0065] It should be noted that since the displacement of the higher-order bulk wave spurious A is concentrated in the dielectric layer 20, in the embodiments of the present application, the second sub-dielectric layer 22 is inserted between two adjacent first sub-dielectric layers 21 in the dielectric layer 20 to weaken the generation and propagation of the higher-order bulk wave spurious A.

[0066] Figure 4 shows Figure 1 the simulation result diagrams of two surface acoustic wave resonators shown in the case where the second sub-dielectric layer 22 is not provided in the dielectric layer 20 (i.e., the prior art) and Figure 2 the case where the second sub-dielectric layer 22 is provided in the dielectric layer 20 (i.e., the present application). From Figure 4 it can be seen that by providing the second sub-dielectric layer 22 in the dielectric layer 20 in the present application, the higher-order bulk wave spurious A can be effectively suppressed, making the peak value of the higher-order bulk wave spurious A become gentler, thereby improving the performance of the surface acoustic wave resonator.

[0067] It should be noted that the interface between the second sub-dielectric layer 22 and at least one adjacent first sub-dielectric layer 21 being an irregular interface includes three implementation manners. The first implementation manner is asFigure 2 As shown, the interface between the second sub - dielectric layer 22 and the first sub - dielectric layer 21 adjacent to the side facing away from the substrate 10 is an irregular interface; the second implementation is as follows Figure 5 As shown, the interface between the second sub - dielectric layer 22 and the first sub - dielectric layer 21 adjacent to the side close to the substrate 10 is an irregular interface; the third implementation is as follows Figure 6 As shown, the interfaces between the second sub - dielectric layer 22 and the two adjacent first sub - dielectric layers 21 are both irregular interfaces.

[0068] It can be understood that when the interfaces between the second sub - dielectric layer 22 and the two adjacent first sub - dielectric layers 21 are both irregular interfaces, compared with the case where the interface between the second sub - dielectric layer 22 and one adjacent first sub - dielectric layer 21 is an irregular interface, it can more effectively reflect the higher - order bulk - wave spurs A, reflect more energy back to the piezoelectric layer 30, thereby further suppressing the higher - order bulk - wave spurs A and improving the performance of the surface acoustic wave resonator.

[0069] It can also be understood that when the interface between the second sub - dielectric layer 22 and the first sub - dielectric layer 21 adjacent to the side facing away from the substrate 10 is an irregular interface, compared with the case where the interface between the second sub - dielectric layer 22 and the first sub - dielectric layer 21 adjacent to the side close to the substrate 10 is an irregular interface, since the irregular surface of the second sub - dielectric layer 22 is closer to the piezoelectric layer 30, therefore, it can more effectively reflect the higher - order bulk - wave spurs A, reflect more energy back to the piezoelectric layer 30, thereby further suppressing the higher - order bulk - wave spurs A and improving the performance of the surface acoustic wave resonator.

[0070] It should also be noted that the present application does not limit the number of the first sub - dielectric layers 21 in the dielectric layer 20. Similarly, the present application does not limit the number of the second sub - dielectric layers 22 in the dielectric layer 20. However, it can be understood that when there are N first sub - dielectric layers 21 in the dielectric layer 20, since there is a second sub - dielectric layer 22 between two adjacent first sub - dielectric layers 21, the number of the second sub - dielectric layers 22 is N - 1, N≥2, and N is an integer.

[0071] Figure 7 Fig. shows a top - view schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present application. As Figure 7 shown, the interdigital transducer 40 includes a first bus bar 41 and a second bus bar 42 arranged oppositely, electrode fingers 431 connected to the first bus bar, and electrode fingers 432 connected to the second bus bar. The electrode fingers 431 connected to the first bus bar and the electrode fingers 432 connected to the second bus bar are alternately arranged along the first direction X, and the electrode fingers 431 / 432 extend along the second direction Y. Figure 7 Taking the case where the first direction X and the second direction Y are perpendicular as an example for illustration. Thus, it can be understood that Figure 2 、 Figure 5 andFigure 6 These are schematic structural diagrams of the surface acoustic wave resonator in a cross-section BB' perpendicular to the second direction Y (i.e., the extending direction of the electrode fingers 431 / 432).

[0072] In addition, as Figure 7 shown, the surface acoustic wave resonator may further include reflection gratings 44 located on the side of the piezoelectric layer 30 away from the substrate 10 and on opposite sides of the interdigital transducer 40 along the first direction X. The reflection gratings 44 are used to reflect acoustic waves, thereby helping to form better resonance and improving the transmission performance of the resonator.

[0073] It should be noted that referring to Figure 2 、 Figure 5 and Figure 6 shown, since the interface between the second sub-medium layer 22 and at least one adjacent first sub-medium layer 21 is an irregular interface, the thickness of the second sub-medium layer 22 and the thickness of the first sub-medium layer 21 cannot be accurately characterized by fixed thickness values. However, it can be understood that in the cross-section BB' perpendicular to the second direction Y, the width of the second sub-medium layer 22 along the first direction X may be equal to the width of the first sub-medium layer 21 along the first direction X, and the equivalent thickness of all the first sub-medium layers 21 may be fixed, so that the sum of the cross-sectional areas of all the first sub-medium layers 21 may be fixed. Thus, the ratio RA1 of the cross-sectional area of the second sub-medium layer 22 to the sum of the cross-sectional areas of all the first sub-medium layers 21 can be used to characterize the ratio of the equivalent thickness of the second sub-medium layer 22 to the equivalent thickness of all the first sub-medium layers 21. The larger the ratio RA1 of the cross-sectional area of the second sub-medium layer 22 to the sum of the cross-sectional areas of all the first sub-medium layers 21, the larger the equivalent thickness of the second sub-medium layer 22 is characterized, and vice versa; similarly, the ratio RA2 of the cross-sectional area of the first sub-medium layer 21 to the sum of the cross-sectional areas of all the first sub-medium layers 21 can be used to characterize the ratio of the equivalent thickness of the first sub-medium layer 21 to the equivalent thickness of all the first sub-medium layers 21. The larger the ratio RA2 of the cross-sectional area of the first sub-medium layer 21 to the sum of the cross-sectional areas of all the first sub-medium layers 21, the larger the equivalent thickness of the first sub-medium layer 21 is characterized, and vice versa.

[0074] On this basis, the inventor took the medium layer 20 including two first sub-medium layers 21 and one second sub-medium layer 22 between the two first sub-medium layers 21 as an example, and used the ratio RA1 of the cross-sectional area of the second sub-medium layer 22 in the cross-section BB' to the sum of the cross-sectional areas of all the first sub-medium layers 21 in the cross-section BB' to characterize the magnitude of the equivalent thickness of the second sub-medium layer 22, and studied the surface acoustic wave resonator with different equivalent thickness second sub-medium layers 22 inserted in the medium layer 20. Figure 8The figure shows the simulation results of a surface acoustic wave resonator with second sub-media layers 22 of different equivalent thicknesses inserted in a media layer 20. Among them, RA1 = 0 means that no second sub-media layer 22 is inserted in the media layer 20. RA1 = 4%, 10%, 18%, and 26% respectively mean that in the cross-section BB' perpendicular to the second direction Y, the cross-sectional area of the second sub-media layer 22 in the media layer 20 accounts for 4%, 10%, 18%, and 26% of the sum of the cross-sectional areas of all the first sub-media layers 21. The larger RA1 is, the greater the equivalent thickness of the second sub-media layer 22 is characterized. From Figure 8 It can be seen that as RA1 increases, that is, as the equivalent thickness of the second sub-media layer 22 inserted in the media layer 20 increases, the higher-order bulk wave spurious A first weakens and then remains unchanged, that is, the suppression effect on the higher-order bulk wave spurious A first enhances and then remains unchanged.

[0075] Therefore, optionally, in some embodiments of the present application, in the cross-section BB' perpendicular to the second direction Y, the ratio RA1 of the cross-sectional area of the second sub-media layer 22 in the media layer 20 to the sum of the cross-sectional areas of all the first sub-media layers 21 can be set to satisfy 4% ≤ RA1 ≤ 18%, so as to insert a second sub-media layer 22 with an appropriate equivalent thickness in the media layer 20 to effectively suppress the higher-order bulk wave spurious A. In this embodiment, the second sub-media layer 22 provided in the media layer 20 can be one layer or at least two layers.

[0076] Specifically, taking the media layer 20 including two first sub-media layers 21 and one second sub-media layer 22 between the two first sub-media layers 21 as an example, as Figure 2 、 Figure 5 and Figure 6 shown, the equivalent total thickness of the two first sub-media layers 21 can be 0.25λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator. For example, when λ = 2μm, when RA1 = 4%, the equivalent thickness of the second sub-media layer 22 inserted between the two first sub-media layers 21 is 20nm; when RA1 = 10%, the equivalent thickness of the second sub-media layer 22 inserted between the two first sub-media layers 21 is 50nm; when RA1 = 18%, the equivalent thickness of the second sub-media layer 22 inserted between the two first sub-media layers 21 is 90nm; when RA1 = 26%, the equivalent thickness of the second sub-media layer 22 inserted between the two first sub-media layers 21 is 130nm.

[0077] Figure 9 The figure shows a schematic structural diagram of another surface acoustic wave resonator provided in an embodiment of the present application in the cross-section BB' perpendicular to the second direction Y, as Figure 9As shown, at least two second sub - dielectric layers 22 are provided in the dielectric layer 20. As known from the foregoing, as the equivalent thickness of the second sub - dielectric layer 22 increases, the suppression effect on the higher - order bulk - wave spurious A first enhances and then remains unchanged. Moreover, considering the process of acoustic wave propagation from the piezoelectric layer 30 to the dielectric layer 20, the interface between the second sub - dielectric layer 22 closer to the piezoelectric layer 30 and the adjacent first sub - dielectric layer 21 can preferentially reflect the higher - order bulk - wave spurious A. Thus, when at least two second sub - dielectric layers 22 are inserted into the dielectric layer 20, optionally, in the cross - section BB' perpendicular to the second direction Y, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the ratio RA1 of the cross - sectional area of each second sub - dielectric layer 22 in the dielectric layer 20 to the sum of the cross - sectional areas of all the first sub - dielectric layers 21 gradually increases.

[0078] That is to say, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the equivalent thickness of each second sub - dielectric layer 22 in the dielectric layer 20 gradually increases. Therefore, during the process of acoustic wave propagation from the piezoelectric layer 30 to the dielectric layer 20, it is preferentially reflected by the interface between the second sub - dielectric layer 22 with a larger equivalent thickness and the adjacent first sub - dielectric layer 21, and the suppression effect on the higher - order bulk - wave spurious A is stronger. As the acoustic wave penetrates deeper into the dielectric layer 20, since the higher - order bulk - wave spurious A has been weakened by the second sub - dielectric layer 22 closer to the piezoelectric layer 30 and with a larger equivalent thickness, thus, the interface between the second sub - dielectric layer 22 with a relatively smaller equivalent thickness and the adjacent first sub - dielectric layer 21 can be further utilized to reflect the higher - order bulk - wave spurious A, effectively suppressing the higher - order bulk - wave spurious A as a whole and improving the performance of the surface acoustic wave resonator.

[0079] In this embodiment, the ratio of the cross - sectional area of each first sub - dielectric layer 21 in the dielectric layer 20 to the sum of the cross - sectional areas of all the first sub - dielectric layers 21 in the cross - section BB' can be equal, or the ratio of the cross - sectional areas of at least two first sub - dielectric layers 21 in the cross - section BB' to the sum of the cross - sectional areas of all the first sub - dielectric layers 21 in the cross - section BB' can be unequal. That is to say, the equivalent thicknesses of each first sub - dielectric layer 21 in the dielectric layer 20 can be equal, or the equivalent thicknesses of at least two first sub - dielectric layers 21 can be unequal, depending on the specific situation.

[0080] When at least two second sub - dielectric layers 22 are inserted into the dielectric layer 20, alternatively, in the cross - section BB' perpendicular to the second direction Y, the ratio RA1 of the cross - sectional area of each second sub - dielectric layer 22 in the dielectric layer 20 to the sum of the cross - sectional areas of all first sub - dielectric layers 21 can also be equal, that is, the equivalent thicknesses of the second sub - dielectric layers 22 in the dielectric layer 20 are equal, which is more convenient to achieve in terms of technology. When the equivalent thicknesses of at least two second sub - dielectric layers 22 in the dielectric layer 20 are not equal, it is also possible that along the direction away from the substrate 10 and closer to the piezoelectric layer 30, the equivalent thicknesses of the second sub - dielectric layers 22 in the dielectric layer 20 gradually decrease, that is, in the cross - section BB' perpendicular to the second direction Y, along the direction away from the substrate 10 and closer to the piezoelectric layer 30, the ratio RA1 of the cross - sectional area of each second sub - dielectric layer 22 in the dielectric layer 20 to the sum of the cross - sectional areas of all first sub - dielectric layers 21 gradually decreases. The above two methods can also use the second sub - dielectric layers 22 inserted in the dielectric layer 20 to suppress the high - order bulk - wave spurious A.

[0081] The inventor also took the dielectric layer 20 including two first sub - dielectric layers 21 and one second sub - dielectric layer 22 between the two first sub - dielectric layers 21 (refer to Figure 2 、 Figure 5 and Figure 6 ) as an example to study the position of the second sub - dielectric layer 22 inserted in the dielectric layer 20. It can be understood that the closer the second sub - dielectric layer 22 inserted in the dielectric layer 20 is to the piezoelectric layer 30, the smaller the equivalent thickness of the first sub - dielectric layer 21 closer to the piezoelectric layer 30 among the two first sub - dielectric layers 21 of the dielectric layer 20, and the smaller the ratio RA21 of the cross - sectional area of the first sub - dielectric layer 21 closer to the piezoelectric layer 30 among the two first sub - dielectric layers 21 of the dielectric layer 20 in the cross - section BB' to the sum of the cross - sectional areas of the two first sub - dielectric layers 21 in the cross - section BB'. Thus, in the cross - section BB' perpendicular to the second direction Y, the ratio RA21 of the cross - sectional area of the first sub - dielectric layer 21 closer to the piezoelectric layer 30 among the two first sub - dielectric layers 21 of the dielectric layer 20 to the sum of the cross - sectional areas of the two first sub - dielectric layers 21 can characterize the position of the second sub - dielectric layer 22 inserted in the dielectric layer 20. The smaller RA21 is, the closer the second sub - dielectric layer 22 inserted in the dielectric layer 20 is to the piezoelectric layer 30, and vice versa.

[0082] Figure 10The figure shows the simulation result diagram of a surface acoustic wave resonator with a layer of second sub-medium layer 22 inserted at different positions in the medium layer 20. Among them, RA21 = 25%, 50%, and 75% respectively represent that in the cross-section BB' perpendicular to the second direction Y, the cross-sectional area of the first sub-medium layer 21 closer to the piezoelectric layer 30 in the two first sub-medium layers 21 of the medium layer 20 accounts for 25%, 50%, and 75% of the sum of the cross-sectional areas of the two first sub-medium layers 21. The smaller RA21 is, the closer the second sub-medium layer 22 inserted in the medium layer 20 is to the piezoelectric layer 30. From Figure 10 It can be seen that as RA21 becomes smaller, that is, as the second sub-medium layer 22 inserted in the medium layer 20 is closer to the piezoelectric layer 30, the higher-order bulk wave spurious A gradually weakens, that is, the better the suppression effect on the higher-order bulk wave spurious A. Therefore, the second sub-medium layer 22 inserted in the medium layer 20 can preferably be located in the upper-middle position of the medium layer 20 closer to the piezoelectric layer 30.

[0083] Specifically, in some embodiments of the present application, referring to Figure 2 、 Figure 5 and Figure 6 as shown, the medium layer 20 includes two first sub-medium layers 21 and a layer of second sub-medium layer 22 between the two first sub-medium layers 21; at this time, in the cross-section BB' perpendicular to the second direction Y, the proportion RA21 of the cross-sectional area of the first sub-medium layer 21 closer to the piezoelectric layer 30 in the two first sub-medium layers 21 of the medium layer 20 can be set to satisfy: 0 < RA21 < 50%. Thus, a layer of second sub-medium layer 22 inserted in the medium layer 20 is arranged in the upper-middle position of the medium layer 20 closer to the piezoelectric layer 30 to more effectively suppress the higher-order bulk wave spurious A and improve the performance of the surface acoustic wave resonator.

[0084] Figure 11 The figure shows a schematic structural diagram of another surface acoustic wave resonator provided by an embodiment of the present application in the cross-section BB' perpendicular to the second direction Y, as Figure 11As shown, there are at least two second sub-media layers 22 provided in the media layer 20. As known from the foregoing, the second sub-media layer 22 inserted in the media layer 20 is preferably located in the upper middle position of the media layer 20 closer to the piezoelectric layer 30, and can more effectively suppress the high-order bulk wave spurious A. Thus, when at least two second sub-media layers 22 are inserted in the media layer 20, optionally, in the cross-section BB' perpendicular to the second direction Y, along the direction away from the substrate 10 and closer to the piezoelectric layer 30, the proportion RA2 of the cross-sectional area of each first sub-media layer 21 in the media layer 20 to the sum of the cross-sectional areas of all first sub-media layers 21 gradually decreases. That is to say, along the direction away from the substrate 10 and closer to the piezoelectric layer 30, the equivalent thickness of each first sub-media layer 21 in the media layer gradually decreases. Thus, the overall second sub-media layers 22 inserted in the media layer 20 are located in the upper middle position of the media layer 20 closer to the piezoelectric layer 30, and have a stronger inhibitory effect on the high-order bulk wave spurious A, further improving the performance of the surface acoustic wave resonator.

[0085] In summary, whether there is one second sub-media layer 22 or at least two second sub-media layers 22 provided in the media layer 20, in the cross-section BB' perpendicular to the second direction Y, along the direction away from the substrate 10 and closer to the piezoelectric layer 30, the proportion RA2 of the cross-sectional area of each first sub-media layer 21 in the media layer 20 to the sum of the cross-sectional areas of all first sub-media layers 21 gradually decreases. When the media layer 20 includes two first sub-media layers 21 and one second sub-media layer 22 between the two first sub-media layers 21, the proportion RA21 of the cross-sectional area of the first sub-media layer 21 closer to the piezoelectric layer 30 in the two first sub-media layers 21 to the sum of the cross-sectional areas of the two first sub-media layers 21 is greater than 0 and less than 50%, so that the overall second sub-media layer 22 inserted in the media layer 20 is located in the upper middle position of the media layer 20 closer to the piezoelectric layer 30, and has a stronger inhibitory effect on the high-order bulk wave spurious A, further improving the performance of the surface acoustic wave resonator.

[0086] In the above embodiments, the ratio RA1 of the cross-sectional area of each second sub-medium layer 22 in the cross-section BB' of the medium layer 20 to the sum of the cross-sectional areas of all first sub-medium layers 21 in the cross-section BB' may be equal, or at least two of the second sub-medium layers 22 may have unequal ratios RA1 of the cross-sectional area in the cross-section BB' to the sum of the cross-sectional areas of all first sub-medium layers 21 in the cross-section BB'. For example, in the cross-section BB' perpendicular to the second direction Y, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the ratio RA1 of the cross-sectional area of each second sub-medium layer 22 in the medium layer 20 to the sum of the cross-sectional areas of all first sub-medium layers 21 gradually increases. That is to say, the equivalent thicknesses of the second sub-medium layers 22 in the medium layer 20 may be equal, or at least two of the second sub-medium layers 22 may have unequal equivalent thicknesses. For example, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the equivalent thicknesses of the second sub-medium layers 22 in the medium layer 20 gradually increase, depending on the specific situation.

[0087] Alternatively, in the cross-section BB' perpendicular to the second direction Y, the ratio RA2 of the cross-sectional area of each first sub-medium layer 21 in the medium layer 20 to the sum of the cross-sectional areas of all first sub-medium layers 21 may also be equal, that is, the equivalent thicknesses of the first sub-medium layers 21 in the medium layer 20 may be equal, which is more convenient to implement in terms of process. Or, in the cross-section BB' perpendicular to the second direction Y, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the ratio RA2 of the cross-sectional area of each first sub-medium layer 21 in the medium layer 20 to the sum of the cross-sectional areas of all first sub-medium layers 21 may also gradually increase, that is, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the equivalent thicknesses of the first sub-medium layers 21 in the medium layer 20 may also gradually increase. The above two methods can also be used to suppress the higher-order bulk wave spurious A by inserting the second sub-medium layers 22 into the medium layer 20, depending on the specific situation.

[0088] As known from the foregoing, the first sub-medium layer 21 may be a silicon dioxide layer, and the first sub-medium layer 21 with a low sound velocity and the second sub-medium layer 22 with a high sound velocity form a sound velocity gradient, which can better confine the energy in the piezoelectric layer 30 and improve the performance of the surface acoustic wave resonator. Further optionally, in some embodiments of the present application, referring to Figure 2 、 Figure 5 - Figure 6 、 Figure 9 and Figure 11As shown, in the dielectric layer 20, the densities of two adjacent first sub-dielectric layers 21 of the second sub-dielectric layer 22 can be set to be different. Since the sound velocities of silica layers with different densities are different, thus, the sound velocities of two adjacent first sub-dielectric layers 21 of the second sub-dielectric layer 22 in the dielectric layer 20 are different. In this way, the sound velocity gradients formed by the second sub-dielectric layer 22 and two adjacent first sub-dielectric layers 21 in the dielectric layer 20 are different, further destroying the continuity of the sound velocity in the dielectric layer 20. On the one hand, the higher-order bulk wave spurious A can be further suppressed. On the other hand, the energy can be further confined in the piezoelectric layer 30, improving the performance of the surface acoustic wave resonator.

[0089] Optionally, in some embodiments of the present application, in the dielectric layer 20, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the density of each first sub-dielectric layer 21 can gradually decrease, such that the sound velocity of each first sub-dielectric layer 21 gradually increases, that is, each first sub-dielectric layer 21 forms a changing gradient with a gradually increasing sound velocity. By superimposing the sound velocity gradients formed by each first sub-dielectric layer 21 with different sound velocities and the adjacent second sub-dielectric layer 22, thus, while effectively suppressing the higher-order bulk wave spurious A, the energy can be further better confined in the piezoelectric layer 30, improving the performance of the surface acoustic wave resonator.

[0090] Optionally, in other embodiments of the present application, in the dielectric layer 20, along the direction away from the substrate 10 and towards the piezoelectric layer 30, the density of each first sub-dielectric layer 21 can gradually increase, such that the sound velocity of each first sub-dielectric layer 21 gradually decreases, that is, each first sub-dielectric layer 21 forms a changing gradient with a gradually decreasing sound velocity. By superimposing the sound velocity gradients formed by each first sub-dielectric layer 21 with different sound velocities and the adjacent second sub-dielectric layer 22, thus, while effectively suppressing the higher-order bulk wave spurious A, the energy can be further better confined in the piezoelectric layer 30, improving the performance of the surface acoustic wave resonator.

[0091] In other embodiments of the present application, the density of each first sub-dielectric layer 21 in the dielectric layer 20 may not gradually decrease or gradually increase along the direction away from the substrate 10 and towards the piezoelectric layer 30. Instead, as long as the densities of two adjacent first sub-dielectric layers 21 of the second sub-dielectric layer 22 are different, such that the second sub-dielectric layer 22 and two adjacent first sub-dielectric layers 21 form a different sound velocity gradient, the higher-order bulk wave spurious A can be effectively suppressed while the energy can be further better confined in the piezoelectric layer 30, improving the performance of the surface acoustic wave resonator.

[0092] Specifically, in some embodiments of the present application, referring to Figure 2 、 Figure 5 and Figure 6As shown, the dielectric layer 20 includes two layers of first sub-dielectric layers 21 and one layer of second sub-dielectric layer 22 between the two layers of first sub-dielectric layers 21. Among them, in the two layers of first sub-dielectric layers 21, the density of the first sub-dielectric layer 21 closer to the substrate 10 is greater than that of the first sub-dielectric layer 21 closer to the piezoelectric layer 30. Thus, the sound velocity of the first sub-dielectric layer 21 closer to the substrate 10 is less than that of the first sub-dielectric layer 21 closer to the piezoelectric layer 30, that is, the sound velocity of the first sub-dielectric layer 21 closer to the piezoelectric layer 30 is greater than that of the first sub-dielectric layer 21 closer to the substrate 10. In this way, the second sub-dielectric layer 22 and the adjacent two layers of first sub-dielectric layers 21 form a differential sound velocity gradient, while effectively suppressing the higher-order bulk wave spurious A, further better confining the energy in the piezoelectric layer 30 and improving the performance of the surface acoustic wave resonator.

[0093] Figure 12 FIG. shows a schematic structural diagram of another surface acoustic wave resonator provided by an embodiment of the present application in a cross-section BB' perpendicular to the second direction Y, as Figure 12 As shown, the dielectric layer 20 may further include a third sub-dielectric layer 23 between the first sub-dielectric layer 21 closest to the piezoelectric layer 30 and the piezoelectric layer 30, and the sound velocity of the third sub-dielectric layer 23 is greater than that of the piezoelectric layer 30. Since the sound velocity of the first sub-dielectric layer 21 is less than that of the piezoelectric layer 30, and the sound velocity of the third sub-dielectric layer 23 is greater than that of the piezoelectric layer 30, therefore, the sound velocity of the third sub-dielectric layer 23 is also greater than that of the first sub-dielectric layer 21, that is, a third sub-dielectric layer 23 with a high sound velocity is inserted between the first sub-dielectric layer 21 closest to the piezoelectric layer 30 and the piezoelectric layer 30. Thus, during the propagation of sound waves from the piezoelectric layer 30 to the dielectric layer 20, there are sound velocity gradients between the piezoelectric layer 30 and the third sub-dielectric layer 23, between the third sub-dielectric layer 23 and the first sub-dielectric layer 21, and between the first sub-dielectric layer 21 and the second sub-dielectric layer 22, and the sound velocity gradients can be designed differently, that is, an additional sound velocity gradient is added, so that the energy can be further better confined in the piezoelectric layer 30 and the performance of the surface acoustic wave resonator can be improved.

[0094] In this embodiment, although the sound velocities of the third sub-dielectric layer 23 and the second sub-dielectric layer 22 are both greater than that of the piezoelectric layer 30, the sound velocity of the third sub-dielectric layer 23 may be equal to that of the second sub-dielectric layer 22, or the sound velocity of the third sub-dielectric layer 23 may not be equal to that of the second sub-dielectric layer 22, depending on the specific situation.

[0095] In this embodiment, the material of the third sub-dielectric layer 23 with a high sound velocity may include at least one of silicon nitride and aluminum nitride.

[0096] Based on any of the above embodiments, optionally, in some embodiments of the present application, the material of the second sub-medium layer 22 includes at least one of silicon nitride, aluminum nitride, and silicon oxynitride.

[0097] In each embodiment of the present application, the piezoelectric layer 30 is a single-crystal piezoelectric layer, which excites acoustic waves through the inverse piezoelectric effect under the excitation of an electric field. The piezoelectric layer 30 can be a lithium niobate LiNbO3 layer or a lithium tantalate LiTaO3 layer. The deposition methods of the piezoelectric layer 30 include single-crystal slicing, chemical vapor deposition (CVD), physical vapor deposition (PVD), etc. Among them, single-crystal slicing requires related processes such as ion implantation and bonding. Specifically, for example, the piezoelectric layer is a 42Y-X lithium tantalate layer, and its thickness can be 0.3λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator.

[0098] In each embodiment of the present application, the interdigital transducer 40 can be made of an aluminum-copper material, and its thickness can be 0.08λ, where λ is the wavelength of the acoustic wave propagating in the surface acoustic wave resonator.

[0099] Correspondingly, an embodiment of the present application further provides a filter, including the surface acoustic wave resonator provided in any of the above embodiments.

[0100] Furthermore, an embodiment of the present application further provides an electronic device, including the above filter.

[0101] Since the surface acoustic wave resonator has been described in detail in the foregoing embodiments, it will not be elaborated here.

[0102] In this specification, each part is described in a combined manner of parallelism and progression. The key point of each part is the difference from other parts. For the same or similar parts among each part, reference can be made to each other.

[0103] Regarding the above description of the disclosed embodiments, the features recorded in each embodiment of this specification can be replaced or combined with each other, so that those skilled in the art can implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A surface acoustic wave resonator, characterized in that: include: substrate; a dielectric layer located on one side of the substrate, the dielectric layer comprising at least two first sub-dielectric layers stacked in a direction away from the substrate, a second sub-dielectric layer being arranged between two adjacent first sub-dielectric layers, and an interface between the second sub-dielectric layer and at least one adjacent first sub-dielectric layer being an irregular interface; The piezoelectric layer is located on a side of the dielectric layer away from the substrate, the acoustic velocity of the first sub-dielectric layer is smaller than the acoustic velocity of the piezoelectric layer, and the acoustic velocity of the second sub-dielectric layer is larger than the acoustic velocity of the piezoelectric layer; An interdigital transducer is located on a side of the piezoelectric layer facing away from the substrate.

2. The surface acoustic wave resonator according to claim 1, characterized in that: Interfaces between the second sub-dielectric layer and two adjacent first sub-dielectric layers are all irregular interfaces.

3. The surface acoustic wave resonator according to claim 1, characterized in that: The IDT comprises a first bus bar and a second bus bar arranged opposite to each other, electrode fingers connected to the first bus bar and electrode fingers connected to the second bus bar, the electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged along a first direction, and the electrode fingers extend along a second direction; In a cross section perpendicular to the second direction, a ratio RA1 of a cross-sectional area of ​​the second sub-dielectric layer to a sum of cross-sectional areas of all the first sub-dielectric layers in the dielectric layer satisfies: 4%≤RA1≤18%.

4. The surface acoustic wave resonator according to claim 1, characterized in that: The IDT comprises a first bus bar and a second bus bar arranged opposite to each other, electrode fingers connected to the first bus bar and electrode fingers connected to the second bus bar, the electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged along a first direction, and the electrode fingers extend along a second direction; At least two second sub-dielectric layers are arranged in the dielectric layer. In a cross section perpendicular to the second direction, along a direction away from the substrate and close to the piezoelectric layer, a ratio RA1 of the cross-sectional area of ​​each second sub-dielectric layer in the dielectric layer to the sum of the cross-sectional areas of all the first sub-dielectric layers gradually increases.

5. The surface acoustic wave resonator according to claim 1, characterized in that: The IDT comprises a first bus bar and a second bus bar arranged opposite to each other, electrode fingers connected to the first bus bar and electrode fingers connected to the second bus bar, the electrode fingers connected to the first bus bar and the electrode fingers connected to the second bus bar are alternately arranged along a first direction, and the electrode fingers extend along a second direction; In a cross section perpendicular to the second direction, along a direction away from the substrate and close to the piezoelectric layer, a ratio RA2 of the cross-sectional area of ​​each first sub-dielectric layer in the dielectric layer to the sum of the cross-sectional areas of all the first sub-dielectric layers gradually decreases.

6. The surface acoustic wave resonator according to claim 5, characterized in that: The dielectric layer includes two layers of the first sub-dielectric layers and a layer of the second sub-dielectric layer between the two layers of the first sub-dielectric layers; In a cross section perpendicular to the second direction, a ratio RA21 of the cross-sectional area of ​​one of the two first sub-dielectric layers of the dielectric layer closer to the piezoelectric layer to the sum of the cross-sectional areas of the two first sub-dielectric layers satisfies: 0 <RA21<50%。 7. The surface acoustic wave resonator according to claim 1, characterized in that: The first sub-medium layer is a silicon dioxide layer; In the dielectric layer, the densities of two adjacent layers of the second sub-dielectric layer are different.

8. The surface acoustic wave resonator according to claim 7, characterized in that: In the dielectric layer, along a direction away from the substrate and close to the piezoelectric layer, the density of each of the first sub-dielectric layers gradually decreases; Alternatively, in the dielectric layer, the density of the first sub-dielectric layer gradually increases along a direction away from the substrate and close to the piezoelectric layer.

9. The surface acoustic wave resonator according to claim 1, characterized in that: The dielectric layer further includes a third sub-dielectric layer located between the first sub-dielectric layer closest to the piezoelectric layer and the piezoelectric layer, and the acoustic velocity of the third sub-dielectric layer is greater than the acoustic velocity of the piezoelectric layer.

10. The surface acoustic wave resonator according to any one of claims 1 to 9, characterized in that: The material of the second sub-dielectric layer includes at least one of silicon nitride, aluminum nitride and silicon oxynitride.

11. A filter, characterized in that: The surface acoustic wave resonator comprises the surface acoustic wave resonator according to any one of claims 1 to 10.

12. An electronic device, characterized in that: Comprising the filter as claimed in claim 11.

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