A surface acoustic wave filter

Abstract

This invention discloses a surface acoustic wave (SAW) filter. It includes: a piezoelectric layer; a plurality of resonators disposed on one side of the piezoelectric layer; and an attenuation structure disposed between two adjacent resonators. The attenuation structure includes at least an elastic wave attenuation material layer, the elastic modulus E1 of which satisfies: E1 ≤ 10 GPa. By including an elastic wave attenuation material layer with an elastic modulus lower than 10 GPa in the attenuation structure between two adjacent resonators, this invention allows the elastic waves leaking from the resonators to be rapidly attenuated within the attenuation structure. This prevents SAW from propagating outside the resonators through the reflector grating or through the gap-pseudo-busbar, thus preventing SAW coupling between adjacent resonators. Furthermore, the fabrication process of the attenuation structure can be the same as existing resonator fabrication processes, allowing for shared equipment, and is simple, easy to implement, and low in cost.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a surface acoustic wave filter. Background Technology

[0002] With technological advancements, competition in communication terminals is intensifying, placing increasingly stringent demands on the performance of various components. Filters are among the core components of communication systems. As terminal products become smaller, surface acoustic wave (SAW) filters have emerged as a leading choice, playing an increasingly crucial role in communication systems. With the advent of 5G mobile communication technology, the performance requirements for filters are also rising, presenting both significant challenges and opportunities for the filter industry.

[0003] Surface acoustic wave (SAW) filters are widely used in radio frequency (RF) front-ends and have advantages such as low insertion loss, wide bandwidth, and small size. However, SAW filters generally contain multiple resonators, and as the filter size shrinks, the resonator layout becomes more compact, and the coupling between resonators becomes more and more obvious, which seriously affects the performance of the filter. Therefore, suppressing the coupling between resonators is of great significance for improving the performance of SAW filters.

[0004] In existing technologies, the following methods are used to suppress coupling between resonators:

[0005] 1. The wafer is processed by etching grooves and doping or etching filling. The process is complex and the wafer etching requires high precision. Otherwise, it will affect the performance of the resonator. In addition, the mechanism of interface reflection is used. The reflected waves will affect the performance of the resonator itself, thereby affecting the overall performance of the filter.

[0006] 2. Using metal traces for grounding to isolate electromagnetic signal coupling, thereby improving device isolation, has no effect on improving the leakage elastic wave, so its improvement effect is limited. Summary of the Invention

[0007] This invention provides a surface acoustic wave filter to address existing methods for suppressing coupling between resonators.

[0008] This invention provides a surface acoustic wave filter, comprising:

[0009] piezoelectric layer;

[0010] Multiple resonators are disposed on one side of the piezoelectric layer;

[0011] An attenuation structure is disposed between two adjacent resonators, the attenuation structure comprising at least an elastic wave attenuation material layer, wherein the elastic modulus E1 of the elastic wave attenuation material layer satisfies: E1≤10GPa.

[0012] Optionally, the lower the operating frequency of the surface acoustic wave filter, the greater the thickness of the elastic wave attenuation material layer.

[0013] Optionally, the thickness H1 of the elastic wave attenuation material layer satisfies: 0.05um ≤ H1 ≤ 5um.

[0014] Optionally, the width W1 of the attenuation structure satisfies: W1≥0.25λ, where λ represents the elastic wave wavelength of the resonator.

[0015] Optionally, the thickness H2 of the attenuation structure satisfies: H2≥H0 / 2, where H0 represents the thickness of the resonator.

[0016] Optionally, the elastic wave attenuation material layer is conductive, or the attenuation structure further includes a conductive layer.

[0017] Optionally, the width W2 of the attenuation structure satisfies: W2 ≥ 0.5λ, where λ represents the elastic wave wavelength of the resonator.

[0018] Optionally, the thickness H3 of the attenuation structure satisfies: H3≥H0, where H0 represents the thickness of the resonator.

[0019] Optionally, the resonator includes a first reflective grating and a second reflective grating arranged along a first direction, and a first busbar and a second busbar arranged along a second direction, wherein the first direction and the second direction intersect.

[0020] Two adjacent resonators include a first resonator and a second resonator arranged along the first direction, and the attenuation structure is located between the second reflective grating of the first resonator and the first reflective grating of the second resonator;

[0021] And / or, two adjacent resonators include a first resonator and a second resonator arranged along the second direction, with the attenuation structure located between the second busbar of the first resonator and the first busbar of the second resonator.

[0022] Optionally, the attenuation structure located between the first busbar and the second busbar at least covers a portion of the first busbar and a portion of the second busbar.

[0023] The technical solution of this invention, by setting an attenuation structure between two adjacent resonators, includes an elastic wave attenuation material layer with an elastic modulus of less than 10 GPa. This allows the elastic waves leaking from the resonators to be rapidly attenuated in the attenuation structure, thereby preventing surface acoustic waves from propagating to the outside of the resonator through the reflector grating or through the gap-pseudo-busbar, and preventing the coupling of surface acoustic waves between adjacent resonators. At the same time, the fabrication process of the attenuation structure can be the same as the existing resonator fabrication process, and the equipment can be shared. The process is simple, easy to implement, and low in cost.

[0024] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the structure of a surface acoustic wave filter provided by the prior art;

[0027] Figure 2 A schematic diagram of the structure of a resonator provided for the prior art;

[0028] Figure 3 A schematic diagram of energy transfer in a resonator provided for the prior art;

[0029] Figure 4 This is a schematic diagram of the structure of a surface acoustic wave filter provided in an embodiment of the present invention;

[0030] Figure 5 A comparison of the simulated admittance characteristic curves of the resonator in the surface acoustic wave filter provided in the embodiment of the present invention and the resonator in the surface acoustic wave filter provided in the prior art;

[0031] Figure 6 This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention;

[0032] Figure 7 for Figure 6 A schematic cross-sectional view of the provided surface acoustic wave filter along section line A-A';

[0033] Figure 8 for Figure 6Another schematic diagram of the surface acoustic wave filter along section line A-A';

[0034] Figure 9 for Figure 6 Another schematic diagram of the surface acoustic wave filter along section line A-A';

[0035] Figure 10 This is a schematic diagram of the structure of another surface acoustic wave filter according to an embodiment of the present invention;

[0036] Figure 11 This is a schematic diagram of the structure of another surface acoustic wave filter according to an embodiment of the present invention;

[0037] Figure 12 This is a schematic diagram of the structure of another surface acoustic wave filter according to an embodiment of the present invention;

[0038] Figure 13 This is a schematic diagram of the structure of another surface acoustic wave filter according to an embodiment of the present invention;

[0039] Figure 14 This is a schematic diagram of the structure of another surface acoustic wave filter according to an embodiment of the present invention;

[0040] Figure 15 This is a schematic diagram of the structure of another surface acoustic wave filter according to an embodiment of the present invention. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices. The terms "upper," "lower," "left," "right," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings and are only used to describe the relative positional relationships between components or constituent parts, and do not specifically limit the specific installation orientation of each component or constituent part.

[0043] Figure 1 A schematic diagram of the structure of a surface acoustic wave filter provided in the prior art is shown below. Figure 1 The existing surface acoustic wave filter 10 includes a piezoelectric layer 21, a resonator 22 located on one side of the piezoelectric layer 21, and metal traces 13 and solder balls 14 located on one side of the piezoelectric layer 21 for transmitting electrical signals. Figure 1 It can be seen that in the existing surface acoustic wave filter 10, the gap between two adjacent acoustic resonators 22 is very small, and surface acoustic waves can easily couple between different resonators 22. It should be noted that the two adjacent resonators 22 can be two resonators 22 adjacent along the first direction X, or two resonators 22 adjacent along the second direction Y. The first direction X is the propagation direction of the surface acoustic wave in the resonator 22, and the intersection of the second direction Y can be perpendicular to each other.

[0044] Figure 2 A schematic diagram of a resonator structure provided for the prior art, for reference. Figure 2 The resonator 22 of the existing surface acoustic wave (SAW) filter includes a transducer 121 and reflective gratings 122 located on both sides of the transducer along a first direction X. More specifically, the transducer 121 includes a bus bar 1211, a pseudo-finger 1212, electrode interdigitates 1213, and a gap 1214 located between the pseudo-finger 1212 and electrode interdigitates 1213 along a second direction Y. The interdigital transducer in the SAW resonator is used for the conversion of acoustic-to-electric and electro-acoustic energy, while the reflective grating is used to reflect SAW waves. It can be understood that, according to Bragg's law, the interdigital structure formed by the alternating arrangement of electrode interdigitates 1213 connected to different bus bars 1211 along the first direction Y can concentrate energy in the resonator 22 at a specific frequency, thereby achieving the filtering function.

[0045] Figure 3 A schematic diagram of energy transfer in a resonator provided for the prior art. Figure 3 The diagram shown illustrates the internal energy transfer of the resonator 22 in the surface acoustic wave filter 10 during its operating frequency band. (Refer to...) Figure 2 and Figure 3 In the operating frequency band, the main energy of the resonator 22 is concentrated in its active region. The active region refers to the area where the electrode interdigitates 1213 connected to different busbars 1211 overlap along the first direction X. Through electroacoustic-acoustic conversion, the low-loss transmission of the filter signal is achieved. However, some energy still leaks out. Part of it leaks through the reflector along the first direction X, and part of it leaks through the gap 1214-dummy finger 1212-busbar 1211.

[0046] Figure 4 This is a schematic diagram of the structure of a surface acoustic wave filter provided in an embodiment of the present invention. Figure 6 This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention. Figure 7 for Figure 6 A schematic cross-sectional view of the surface acoustic wave filter along section line A-A' is provided for reference. Figure 4 , Figure 6 and Figure 7 The surface acoustic wave filter 20 provided in this embodiment of the invention includes: a piezoelectric layer 21; a plurality of resonators 22 disposed on one side of the piezoelectric layer 21; and an attenuation structure 23 disposed between two adjacent resonators 22. The attenuation structure 23 includes at least an elastic wave attenuation material layer 231, and the elastic modulus E1 of the elastic wave attenuation material layer 231 satisfies: E1≤10GPa.

[0047] For example, the material of the elastic wave attenuation material layer 231 in the embodiments of the present invention can be a low-stiffness material or a viscoelastic material such as resin, polyimide (PI), polyethylene (PE), rubber, gel, or photoresist. The piezoelectric layer 21 in the embodiments of the present invention can be a single-layer structure supported by piezoelectric materials such as LiTaO3, LiNbO3, quartz, or AlN, or it can be a multilayer structure containing piezoelectric materials.

[0048] Figure 4 The embodiment shown places the attenuation structure 23 between the reflective grids of the two resonators 22. In this case, the attenuation structure 23 can absorb the surface acoustic waves that leak through the reflective grid by utilizing its high attenuation absorption capability for surface acoustic waves, thereby eliminating the mutual influence of surface acoustic waves between the two resonators 22.

[0049] Figure 5This is a comparison of the simulated admittance characteristic curves of the resonator in the surface acoustic wave filter provided in the embodiment of the present invention and the resonator in the surface acoustic wave filter provided in the prior art. It should be noted that... Figure 5 Curve S1 in the figure represents the surface acoustic wave filter (e.g., the one provided in the embodiment of the present invention) Figure 4 The simulated admittance characteristic curve of resonator 22 in the surface acoustic wave filter shown is given by curve S2, which represents the surface acoustic wave filter provided by the prior art (and...). Figure 4 The only difference between the surface acoustic wave filter shown is the absence of an attenuation structure. The simulated admittance characteristic curve of the resonator 22 in this embodiment of the invention is shown below. Compared to existing surface acoustic wave filters, the resonator 22 in this embodiment has an intercalation electrode thickness of 380 nm, a duty cycle of 0.5, a wavelength of 4 μm for one of two adjacent resonators 22, a wavelength of 4.1 μm for the other, and a distance of 4 μm between adjacent resonators 22. The attenuation structure 23 in this embodiment uses a single layer of photoresist with a thickness of 400 nm and a width of 3 μm.

[0050] refer to Figure 5 From the comparison results, it can be seen that there is a significant clutter to the left of the resonance peak of the resonator 22 in the surface acoustic wave filter of the prior art. This clutter is caused by the leakage elastic wave from the resonator 22 adjacent to the resonator 22 in the surface acoustic wave filter. However, the corresponding resonator 22 in the embodiment of the present invention does not have this clutter. The admittance peak value of the resonator 22 at the anti-resonance point in the surface acoustic wave filter of the present invention is better than that in the prior art. This indicates that the energy coupling between two adjacent resonators 22 in the prior art will cause the energy to be disconcentrated in the resonant master mode, thereby affecting the performance of the master mode. By comparison, it can be shown that the embodiment of the present invention can significantly improve the performance degradation of the resonator 22 caused by the leakage of elastic waves between the resonators 22.

[0051] exist Figure 6 In the embodiment shown, the attenuation structure 23 is located between the busbars of the two resonators 22. At this time, the attenuation structure 23 can absorb the surface acoustic waves that pass through the gap-finger-busbar by utilizing its high attenuation absorption capability for surface acoustic waves, thereby eliminating the mutual influence of surface acoustic waves between the two resonators 22.

[0052] Figure 8 for Figure 6 Another schematic diagram of the surface acoustic wave filter along section line A-A' is provided for reference. Figure 8 In this embodiment of the invention, the attenuation structure 23 is located in the etched groove of the piezoelectric layer 21 between the busbars of the two resonators 22. At this time, the attenuation structure 23 can still absorb the surface acoustic waves that pass through the gap-finger-busbar.

[0053] In this embodiment of the invention, by setting an attenuation structure 23 located between two adjacent resonators 22, including an elastic wave attenuation material layer 231 with an elastic modulus lower than 10 GPa, the elastic waves leaking from the resonators 22 can be rapidly attenuated in the attenuation structure 23. This can prevent surface acoustic waves from propagating to the outside of the resonators 22 through the reflector grating or through the gap-pseudo-busbar, and prevent the surface acoustic waves between adjacent resonators 22 from coupling. At the same time, the fabrication process of the attenuation structure 23 can be the same as the existing fabrication process of the resonator 22, and the equipment can be shared. The process is simple, easy to implement, and low in cost.

[0054] It should be noted that the lower the operating frequency of the surface acoustic wave filter 20, the greater the thickness of the elastic wave attenuation material layer 231.

[0055] In one feasible implementation, the thickness H1 of the elastic wave attenuation material layer 231 satisfies: 0.05um≤H1≤5um.

[0056] It should be noted that the thicker the elastic wave attenuation material layer 231, the better its suppression effect on leaked elastic waves.

[0057] In one feasible implementation, the width W1 of the attenuation structure 23 satisfies: W1≥0.25λ, where λ represents the elastic wave wavelength of the resonator 22.

[0058] In one feasible implementation, the thickness H2 of the attenuation structure 23 satisfies: H2≥H0 / 2, where H0 represents the thickness of the resonator 22.

[0059] Figure 9 for Figure 6 Another cross-sectional schematic diagram of the surface acoustic wave filter along section line A-A' is provided, for reference. Figure 9 In this embodiment of the invention, the elastic wave attenuation material layer 231 is conductive, or the attenuation structure 23 further includes a conductive layer 232.

[0060] For example, when a conductive attenuation structure 23 is used, such as a conductive elastic wave attenuation material (e.g., conductive rubber) or one of its layers is a conductive material, the attenuation structure 23 can absorb not only elastic waves but also electromagnetic waves, thereby achieving electromagnetic isolation.

[0061] exist Figure 9 In the illustrated embodiment, the attenuation structure 23 is located between the busbars of the two resonators 22. The attenuation structure 23 includes a stacked elastic wave attenuation material layer 231 and a conductive layer 232. The elastic wave attenuation material layer 231 is made of a material with high attenuation absorption for elastic waves, used to absorb surface acoustic waves that can pass through the gap-finger-busbar. By providing the conductive layer 232 made of a conductive material (metal), electromagnetic signal isolation can be achieved.

[0062] It should be noted that the attenuation structure 23 in the embodiments of the present invention may also include a reliable layer made of dense material (SiO2 / SiN / Si, etc.), which can be used to improve the reliability of the attenuation structure 23; the attenuation structure 23 may also include a heat dissipation layer supported by a high thermal conductivity material (Al / Cu / Ag, etc.), which can be used for heat dissipation of the filter.

[0063] exist Figure 9 In the embodiment shown, the elastic wave attenuation material layer 231 is located on the surface of the piezoelectric layer 21. It should be noted that in other feasible embodiments, the elastic wave attenuation material layer 231 may also be located on the side of the conductive layer 232 away from the piezoelectric layer 21, or on the side of the functional layer made of other materials (such as the aforementioned reliability layer and heat dissipation layer) away from the piezoelectric layer 21.

[0064] Based on the above embodiments, if the elastic wave attenuation material layer 231 in the embodiments of the present invention is conductive, or the attenuation structure 23 further includes a conductive layer 232, then the width W2 of the attenuation structure 23 in the embodiments of the present invention satisfies: W2≥0.5λ, where λ represents the elastic wave wavelength of the resonator 22.

[0065] Based on the above embodiments, if the elastic wave attenuation material layer 231 in the embodiments of the present invention is conductive, or the attenuation structure 23 further includes a conductive layer 232, then the thickness H3 of the attenuation structure 23 in the embodiments of the present invention satisfies: H3≥H0, where H0 represents the thickness of the resonator 22.

[0066] refer to Figure 4 and Figure 6 The resonator 22 includes a first reflective grating 221 and a second reflective grating 222 arranged along a first direction X, and a first bus bar 223 and a second bus bar 224 arranged along a second direction Y, wherein the first direction X and the second direction Y intersect; two adjacent resonators 22 include a first resonator 22A and a second resonator 22B arranged along the first direction X, and an attenuation structure 23 is located between the second reflective grating 222 of the first resonator 22A and the first reflective grating 221 of the second resonator 22B; and / or, two adjacent resonators 22 include a first resonator 22A and a second resonator 22B arranged along the second direction Y, and an attenuation structure 23 is located between the second bus bar 224 of the first resonator 22A and the first bus bar 223 of the second resonator 22B.

[0067] It should be noted that the definition of the first direction X in the embodiments of the present invention is the same as that of the first direction X in the prior art, and will not be repeated here. In addition, the first direction X in the embodiments of the present invention can also be perpendicular to the second direction Y.

[0068] Figure 10This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention. Figure 11 This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention, with reference to... Figure 10 and Figure 11 The attenuation structure 23 located between the first bus bar 223 and the second bus bar 224 at least covers a portion of the first bus bar 223 and a portion of the second bus bar 224.

[0069] exist Figure 10 In the embodiment shown, the attenuation structure 23 is located between the busbars of the two resonators 22 and covers part of the busbars. In this case, the attenuation structure 23 can also absorb the surface acoustic waves that pass through the gap-finger-busbar, thereby eliminating the mutual influence of surface acoustic waves between the two resonators 22.

[0070] exist Figure 11 In the illustrated embodiment, the attenuation structure 23 is located between the busbars of the two resonators 22 and covers part of the busbars and the dummy finger. In this case, the attenuation structure 23 can also "absorb" the surface acoustic waves passing through the gap-dummy finger-busbar, thereby eliminating the mutual influence of the surface acoustic waves between the two resonators 22. It should be noted that for elastic wave modes such as Rayleigh waves, which are dominated by vibrations perpendicular to the surface of the piezoelectric layer 21, the attenuation structure 23 should ideally not cover the dummy finger. For elastic wave modes such as horizontal shear waves (SH), which are dominated by vibrations parallel to the surface of the piezoelectric layer 21, the attenuation structure 23 can further cover the gap and a small portion of the electrode inserts, and the length of the covered electrode inserts should be less than the wavelength of the surface acoustic wave.

[0071] It should be noted that the shape of the attenuation structure 23 in the embodiments of the present invention can be as follows: Figure 4 , Figure 6 , Figure 10 and Figure 11 The whole shown can also be composed of multiple separate structures. The separate structures need to be arranged according to a specific rule, as long as they contain a layer of attenuating material.

[0072] Figure 12 This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention. Figure 12 In the illustrated embodiment, the attenuation structure 23 is strip-shaped and arranged in a pattern similar to a reflective grating. In this case, the width and spacing of each individual strip in the attenuation structure 23 are related to the wavelength to be attenuated, achieving a strong attenuation amplitude within a specific frequency range in a relatively small space. Specifically, if the elastic wave velocity in the region where the attenuation structure 23 is located is Vs, and the elastic wave velocity in the active region of the resonator 22 is Vi, corresponding to a wavelength λi, then the sum of the width W and spacing S of the strips in the attenuation structure 23 satisfies the following correspondence:

[0073] And 0.2≤W / S≤5.

[0074] Figure 13 This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention. Figure 13 In the illustrated embodiment, the shape of the attenuation structure 23 is also strip-shaped, and the width and spacing of the individual strips in the attenuation structure 23 are set in accordance with... Figure 11 The attenuation structure 23 shown is the same, except that the attenuation structure 23 is placed between the busbars of the resonator 22.

[0075] Figure 14 This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention. Figure 14 In the illustrated embodiment, the attenuation structure 23 is in the shape of short strips, arranged in a lattice at certain intervals. The distance and size of each short strip of the attenuation structure 23 are related to the wavelength of the corresponding resonator 22, thus achieving a strong attenuation amplitude for a specific frequency band. Specifically, if the elastic wave velocity in the region where the attenuation structure 23 is located is Vs, and the elastic wave velocity in the active region of the resonator 22 is Vi, with a corresponding wavelength of λi, then the sum of the width W and the spacing S of the strips of the attenuation structure 23 satisfies the following correspondence:

[0076] And 0.2≤W / S≤5, the gap A in the length direction of the short strip structure is ≤W+S, and the length L of the short strip structure is ≥W.

[0077] Figure 15 This is a schematic diagram of another surface acoustic wave filter according to an embodiment of the present invention. Figure 15 In the embodiment shown, the attenuation structure 23 is conductive and its shape is a strip arranged in a manner similar to a reflective grating. At this time, the attenuation structure 23 alternates between short-circuited and open-circuited strips. The width and spacing of the strip structure are related to the wavelength to be attenuated, which can achieve a strong attenuation amplitude in a specific frequency range within a small space.

[0078] In one feasible implementation, an attenuation structure 23 is added between any two resonators 22 in the surface acoustic wave filter 20, which helps to reduce the coupling caused by surface acoustic wave leakage between the resonators 22.

[0079] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A surface acoustic wave filter, characterized by, The surface acoustic wave filter comprises: a piezoelectric layer; a plurality of resonators arranged on one side of the piezoelectric layer; a damping structure arranged between two adjacent resonators, the damping structure comprising at least an elastic wave damping material layer, the elastic modulus E1 of the elastic wave damping material layer satisfying: E1≤10Gpa; the resonator comprising a first reflective grating and a second reflective grating arranged along a first direction, and a first bus bar and a second bus bar arranged along a second direction, the first direction and the second direction intersecting; the two adjacent resonators comprising a first resonator and a second resonator arranged along the first direction, the damping structure being located between the second reflective grating of the first resonator and the first reflective grating of the second resonator; and / or, the two adjacent resonators comprising a first resonator and a second resonator arranged along the second direction, the damping structure being located between the second bus bar of the first resonator and the first bus bar of the second resonator; the damping structure located between the first bus bar and the second bus bar covering at least part of the first bus bar and part of the second bus bar; the resonator further comprising a dummy finger; the damping structure located between the first bus bar and the second bus bar covering part of the dummy finger; the shape of the damping structure is a finger-shaped structure; the sum of the width W and the pitch S of the finger-shaped structure of the damping structure satisfies the following corresponding relationship: and 0.2 < W / S < 5; wherein Vs represents the elastic wave velocity of the region where the damping structure is located, Vi represents the elastic wave velocity of the active region of the resonator, and λi represents the elastic wave wavelength of the active region of the resonator.

2. The surface acoustic wave filter according to claim 1, characterized by, The lower the frequency band of the surface acoustic wave filter, the greater the thickness of the elastic wave damping material layer.

3. The surface acoustic wave filter according to claim 1, characterized by, The thickness H1 of the elastic wave damping material layer satisfies: 0.05um≤H1≤5um.

4. The surface acoustic wave filter according to claim 1, characterized by, The width W1 of the damping structure satisfies: W1≥0.25λ, λ representing the elastic wave wavelength of the resonator.

5. The surface acoustic wave filter according to claim 1, wherein The thickness H2 of the damping structure satisfies: H2≥H0 / 2, H0 representing the thickness of the resonator.

6. The surface acoustic wave filter according to claim 1, wherein The damping structure further comprises a conductive layer laminated with the elastic wave damping material layer.

7. The surface acoustic wave filter according to claim 6, characterized by, The width W2 of the damping structure satisfies: W2≥0.5λ, λ representing the elastic wave wavelength of the resonator.

8. The surface acoustic wave filter according to claim 6, wherein The thickness H3 of the damping structure satisfies: H3≥H0, H0 representing the thickness of the resonator.

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