A surface acoustic wave resonator and a surface acoustic wave filter

Abstract

The application relates to the technical field of semiconductors, in particular to a surface acoustic wave resonator and a surface acoustic wave filter, wherein the surface acoustic wave resonator comprises a piezoelectric layer, the surface of the piezoelectric layer is provided with an active transducing unit and a reflecting unit; two first bus bars are arranged at intervals on the active transducing unit, and two second bus bars are arranged at intervals on the reflecting unit; a first interval region formed by the projection of the two first bus bars along a first direction covers a second interval region formed by the projection of the two second bus bars along the first direction, and the length of the first interval region along a second direction is greater than the length of the second interval region along the second direction, so that the winding distance of the first bus bar when connected with an external circuit is reduced, the space occupation is reduced, the resonator layout is more compact, and the core demand of high-density integration of devices in the semiconductor field is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a surface acoustic wave resonator and a surface acoustic wave filter. BACKGROUND

[0002] In the field of semiconductor, the structure of a conventional single surface acoustic wave (SAW) resonator comprises an active transducing unit and reflection units arranged on both sides of the active transducing unit respectively; the length of the active transducing unit and the reflection units in the direction perpendicular to the propagation direction of the acoustic wave is consistent, that is, the bus bars of the two units are arranged in a flush state.

[0003] However, in the layout design of the SAW filter, when the electrical connection of two resonators in the direction of the acoustic wave propagation is required, the core problem appears: the bus bar of the active transducing unit of the former resonator is directly blocked by the bus bars of the reflection units on both sides of the former resonator, and if the connection with the latter resonator is to be completed, the bus bar of the active transducing unit of the latter resonator needs to bypass the periphery of the bus bar of the reflection unit of the former resonator at the same time, and the bus bar of the active transducing unit of the latter resonator also needs to bypass the periphery of the bus bar of the reflection unit of the latter resonator, so that the two bus bars can be connected.

[0004] The forced bypass design of the bus bar occupies a large amount of filter layout space, which directly leads to the difficulty of adapting the conventional SAW resonator to the core application requirement of high-density integration in the field of semiconductor. SUMMARY

[0005] The present application aims to provide a surface acoustic wave resonator and a surface acoustic wave filter, and solve the problem of how to further reduce the space in the layout of the surface acoustic wave filter when connecting the surface acoustic wave resonator.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] The present application provides a surface acoustic wave resonator, which comprises a piezoelectric layer, and the surface of the piezoelectric layer is provided with an active transducing unit and a reflection unit; two first bus bars are arranged at intervals on the active transducing unit, and two second bus bars are arranged at intervals on the reflection unit; the first interval region formed by the projection of the two first bus bars in the first direction covers the second interval region formed by the projection of the two second bus bars in the first direction, and the length of the first interval region in the second direction is greater than the length of the second interval region in the second direction; the projection of the first bus bar in the second direction does not intersect with the projection of the second bus bar in the second direction; and the first direction is perpendicular to the second direction.

[0008] Preferably, the present application further comprises a third bus bar, which extends in the first direction and is connected with the first bus bar; the projections of the first bus bar and the third bus bar in the first direction intersect or completely overlap.

[0009] Preferably, the inner side of each of the first bus bars is provided with a plurality of first prongs extending towards each other, and the plurality of first prongs are staggered along a first direction; and the length of the overlapping area of the plurality of first prongs along a second direction is equal to the length of the two second bus bars along the second direction.

[0010] Preferably, the length of the second bus bar along the second direction is less than the length of the first bus bar along the second direction.

[0011] Preferably, in the resonator structure with hammerhead structure at the end of the first prong, the end of each of the plurality of first prongs is provided with a protrusion; and the length of the second bus bar along the second direction is less than or equal to the length of the protrusion.

[0012] Preferably, the side of the overlapping area of the plurality of first prongs along the first direction is continuously or intermittently provided with a first dielectric structure, the reflection unit is provided with a second dielectric structure continuously or intermittently corresponding to the first dielectric structure along the first direction, a plurality of second prongs extending along the second direction are provided between the two second bus bars, and the second dielectric structure covers the second bus bar or covers the second bus bar and the second prong.

[0013] Preferably, the first bus bar is provided with a plurality of stub prongs arranged alternately with the first prongs, and the length of the second bus bar along the second direction is less than the length of the stub prong along the second direction.

[0014] Preferably, a plurality of first gratings are provided between the first bus bar and the overlapping area of the plurality of first prongs along the second direction, each of the first gratings extends along the first direction and crosses the plurality of first prongs; two adjacent second prongs are staggered along the first direction, a plurality of second prongs located on the same straight line are connected to a second grating at the end of the second prong, the plurality of second gratings correspond to the plurality of first gratings in number and are arranged in the same way, and the outermost second grating is the second bus bar.

[0015] Also provided is a surface acoustic wave filter comprising the surface acoustic wave resonator according to any one of the above.

[0016] Preferably, a bottom metal electrode layer is further included, the piezoelectric layer is arranged on the bottom metal electrode layer, and the bottom metal electrode layer is used to limit the interval range of two adjacent resonators.

[0017] Compared with the prior art, the present application has the following beneficial effects: by a surface acoustic wave resonator, a piezoelectric layer is provided with an active transducing unit and a reflecting unit; two first bus bars are provided at intervals on the active transducing unit, and two second bus bars are provided at intervals on the reflecting unit; a first interval area formed by the projection of the two first bus bars along a first direction covers a second interval area formed by the projection of the two second bus bars along the first direction, and the length of the first interval area along a second direction is greater than the length of the second interval area along the second direction; the projection of the first bus bar along the second direction does not intersect with the projection of the second bus bar along the second direction; the first direction is perpendicular to the second direction; by covering the second interval area formed by the projection of the two second bus bars along the first direction with the first interval area formed by the projection of the two first bus bars along the first direction, and by making the length of the first interval area along the second direction greater than the length of the second interval area along the second direction, the winding distance of the first bus bar when connected to an external circuit is reduced, thereby reducing the original space occupation, and when this seemingly small change is diffused to the entire filter, the original size can be reduced by a predictable multiple, thereby reducing the cost, reducing the process difficulty and the risk of failure, making the resonator layout more compact, and thereby meeting the core demand of high-density integration of devices in the semiconductor field. BRIEF DESCRIPTION OF DRAWINGS

[0018] 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 needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0019] The structures, proportions, sizes, etc. shown in the drawings of the present specification are only used to cooperate with the content disclosed in the specification, to enable those skilled in the art to understand and read, and are not used to limit the conditions that the present application can be implemented, so they do not have technical significance. Any modification of structure, change of proportion relationship or adjustment of size, without affecting the effects that the present application can produce and the purposes that the present application can achieve, should still fall within the scope of the technical content disclosed by the present application.

[0020] Figure 1 It is a wiring structure schematic diagram of the existing resonator;

[0021] Figure 2 It is a wiring structure schematic diagram of a surface acoustic wave resonator proposed by the embodiment of the present application;

[0022] Figure 3 It is another wiring structure schematic diagram of a surface acoustic wave resonator proposed by the embodiment of the present application;

[0023] Figure 4 This is a schematic diagram of another wiring structure for a surface acoustic wave resonator proposed in an embodiment of this application;

[0024] Figure 5 A schematic diagram of the wiring structure for connecting two existing resonators;

[0025] Figure 6 This is a schematic diagram of the wiring structure connecting two resonators in a surface acoustic wave resonator according to an embodiment of this application;

[0026] Figure 7 This is a schematic diagram of a wiring structure with a protrusion for a surface acoustic wave resonator according to an embodiment of this application;

[0027] Figure 8 This is a schematic diagram of a wiring structure with a dielectric layer for a surface acoustic wave resonator according to an embodiment of this application;

[0028] Figure 9 This is a schematic diagram of another wiring structure with a dielectric structure for a surface acoustic wave resonator proposed in an embodiment of this application;

[0029] Figure 10 This is a schematic diagram of a wiring structure with a short truncated finger for a surface acoustic wave resonator according to an embodiment of this application;

[0030] Figure 11 This is a schematic diagram of a wiring structure with grid strips for a surface acoustic wave resonator according to an embodiment of this application;

[0031] Illustration:

[0032] 10. First busbar; 11. First interdigitated finger; 12. First spacer region; 13. Protrusion; 14. First dielectric structure; 15. Short truncated finger; 16. First grid bar; 20. Second busbar; 21. Second interdigitated finger; 22. Second spacer region; 23. Second dielectric structure; 24. Second grid bar; 30. Third busbar; 40. Piezoelectric layer; 50. Bottom metal electrode layer. Detailed Implementation

[0033] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] See Figure 2 This invention provides a surface acoustic wave resonator, including a piezoelectric layer 40. The surface of the piezoelectric layer 40 is provided with an active transducer unit and a reflector unit. The active transducer unit is provided with two first busbars 10 spaced apart, and the reflector unit is provided with two second busbars 20 spaced apart. A first interval region 12 formed by the projection of the two first busbars 10 along a first direction covers a second interval region 22 formed by the projection of the two second busbars 20 along the first direction, and the length of the first interval region 12 along a second direction is greater than the length of the second interval region 22 along the second direction. The projections of the first busbars 10 along the second direction and the projections of the second busbars 20 do not intersect. The first direction is perpendicular to the second direction.

[0037] It should be noted that the core function of the active transducer unit is to complete the energy form conversion. It is the active component for generating surface acoustic waves. In the industry, interdigital transducers (IDTs) are commonly used. They include multiple pairs of staggered metal interdigital electrodes (first interdigital electrodes 11) and two spaced-apart first busbars 10 (connecting the odd and even ends of the interdigital electrodes respectively, serving as the "bus" for electrical signal input and output). Functionally, it has both forward conversion (receiving external electrical signals and exciting the surface of the piezoelectric layer to generate surface acoustic waves through the piezoelectric effect) and reverse conversion (returning the surface acoustic waves reflected back by the reflecting unit to electrical signals through the inverse piezoelectric effect and summing them for output). The external electrical signal is evenly distributed to each interdigital electrode through the first busbars 10. The alternating electric field formed between adjacent interdigitals causes the piezoelectric layer to undergo periodic mechanical deformation. The deformation propagates along the surface to form surface acoustic waves. When the reflected surface acoustic waves act on the interdigital electrodes, they are converted back into electrical signals through the inverse piezoelectric effect, completing the closed loop of acoustic-electric conversion.

[0038] The reflecting unit is a passive key component that confines acoustic wave energy and constructs the resonant cavity. Its structure is usually based on multiple sets of metal reflecting gratings (second interdigitated fingers 21) that match the wavelength of surface acoustic waves, and is equipped with two spaced second busbars 20 (used to fix the two ends of the reflecting gratings to ensure structural consistency, and in some designs also serve as grounding anti-interference functions). This prevents the surface acoustic waves excited by the active transducer from spreading to the outside of the resonator, reduces energy loss, and reflects the acoustic waves directionally back to the active transducer region, providing conditions for the formation of standing waves. When the surface acoustic waves excited by the active transducer propagate to the reflecting unit, the metal reflecting gratings reflect the acoustic waves along the original propagation path due to the difference between the acoustic impedance and the piezoelectric layer. Since the spacing of the reflecting gratings matches the wavelength of the acoustic waves, the reflected waves can be superimposed in phase with the newly excited acoustic waves of the active transducer, ultimately forming a stable standing wave between the "active unit and the reflecting unit".

[0039] In this embodiment, the first direction is the direction of sound wave propagation (X direction in the figure), and the second direction is perpendicular to the direction of sound wave propagation (Y direction in the figure). In conventional designs, the active transducer and reflector in the resonator have the same length in the Y direction. This means that when the busbar of the transducer is connected to the external circuit, it needs to be rerouted along the Y direction and then rewired along the X direction to bypass the interference of the busbar of the reflector, which occupies more layout space.

[0040] It should be noted that, as Figure 1 Previously, the aperture of the reflecting unit was set to be the same size as the aperture of the active transducer unit to capture all wave energy. In this embodiment, based on the original resonator internal structure distribution, the first interval region 12 formed by the projection of the two first busbars 10 along the first direction covers the second interval region 22 formed by the projection of the two second busbars 20 along the first direction, and the length of the first interval region 12 along the second direction is greater than the length of the second interval region 22 along the second direction. That is, in the new layout, the first busbar 10 crosses or partially crosses the area projected by the second busbar 20 in its projection, and the overall length of its active transducer unit in the Y direction is greater than the length of the reflecting unit in the Y direction, so that the outer sides of the two units are no longer flush in the X direction, effectively reducing the overall size of the reflecting unit in the Y direction. This also means that the distance the first busbar 10 needs to travel along the Y direction when connecting to external circuits is reduced, thereby reducing the original space occupation. When this seemingly minor change is applied to the entire filter, the original size can be reduced by a predictable factor, thereby reducing costs, lowering the manufacturing difficulty and failure risk, and making the resonator layout more compact, thus meeting the core requirement of the semiconductor industry for high-density device integration.

[0041] It should also be noted that, due to the reduction in the overall size of the reflector in the Y direction, the aperture of the reflector also decreases accordingly. This inevitably leads to energy leakage at the edges of the aperture of the active transducer, resulting in a reduction in the original resonance efficiency. However, in reality, due to the diffraction effect, surface acoustic waves will diffuse and bend as they propagate outward from the edges of the active transducer or reflector. The bent vibration mode has concentrated energy in the center and weaker energy at the edges, meaning that the leaked energy is extremely weak wave energy. Most of the core energy in the center can still be captured, so it has almost no impact on the overall resonance efficiency. In this case, for the art, sacrificing the weak energy already at the edges due to the reduction in the size of the reflector in exchange for the significant reduction in overall size, volume, and weight brought about by the reduction in the size of the reflector is completely acceptable.

[0042] In another embodiment, a third busbar 30 is also included, which extends along a first direction and connects to the first busbar 10, wherein the projections of the first busbar 10 and the third busbar 30 along the first direction intersect or completely overlap.

[0043] It should be noted that the third bus 30 serves as an extension of the first bus 10 for connecting to external circuits; the two can be integrated or separate components. In this embodiment, the third bus 30 and the second bus 20 are parallel to each other along the first direction and maintain the minimum rated design spacing. If the third bus 30 continuously approaches the resonant cavity until it completely overlaps with the first bus 10, due to the rated design spacing requirement, the two second buses 20 will continuously move closer to the inner center, meaning the size of the reflecting unit will become smaller and smaller. Conversely, the smaller the size of the reflecting unit, the closer the third bus 30 and the first bus 10 will become to overlap.

[0044] In another embodiment, such as Figure 3 The inner sides of the two first busbars 10 are provided with a plurality of first interdigitated fingers 11 extending in opposite directions, and the plurality of first interdigitated fingers 11 are staggered along the first direction; the length of the overlapping area of ​​the plurality of first interdigitated fingers 11 along the second direction is equal to the length between the outer sides of the two second busbars 20 along the second direction.

[0045] Understandably, the overlapping area of ​​the multiple first interdigitates 11, which is also the aperture region of the active transducer, has a length in the Y direction greater than the length between the outer sides of the two second busbars 20, i.e., the overall length of the reflector unit. With this arrangement, the reflector unit is completely positioned between the extensions of the two first busbars 10, and the third busbar 30 obtains a space that completely overlaps with the first busbars 10. This further reduces the overall layout space required for the resonator and allows the filter to integrate more resonators or other components.

[0046] In another embodiment, such asFigure 4 The length of the second busbar 20 along the second direction is less than the length of the first busbar 10 along the second direction.

[0047] It should be noted that, in order to further improve the effect of the reflection unit in capturing and reflecting the surface acoustic waves emitted by the active transducer, while keeping the overall size of the reflection unit unchanged along the second direction, the length of the second busbar 20 in the Y direction is further reduced, so as to give more extension space to the second forked finger 21 of the reflection unit. The lengthened second forked finger 21 can capture and reflect more surface acoustic wave energy, thereby improving the overall resonance effect of the resonator.

[0048] In conjunction with the above embodiments, in the filter layout structure, two adjacent resonators are connected, and the solution of this application embodiment can significantly reduce the layout space. For example... Figure 5 and Figure 6 The active transducer, the reflector and the third busbar 30 are disposed on the piezoelectric layer 40 as the top metal electrode layer, and the piezoelectric layer 40 is disposed on the bottom metal electrode layer 50. Figure 5 In the original layout, the required total length L1 of two adjacent resonators in the Y direction is L1 = 2 x the length of the bottom metal electrode layer 50 region M + 4 x the length of the third busbar 30 A + 2 x the resonator length B + 4 x the rated design spacing C. However, in the embodiments of this application, as... Figure 6 When the reflecting unit is completely positioned between the two first busbars 10, the required total length L2 of the two adjacent resonators in the Y direction is 2 x the length M of the bottom metal electrode layer 50 region + 2 x the resonator length B. In comparison, the required total length L2 of the two adjacent resonators in the Y direction in this embodiment is shortened by 4 x the length A of the third busbar 30 + 4 x the rated design spacing C compared to the original layout. Therefore, by fine-tuning the relative position of the reflecting unit and the active transducer, the second busbar 20 of the reflecting unit is moved inward, thereby reducing the winding range and length of the first busbar 10 (or the third busbar 30) of the active transducer when connecting to the external circuit. This translates to a greater saving of area in the connection layout of the two resonators and even the entire filter, allowing for the integration of more resonators and improving overall space utilization.

[0049] The resonator structure provided in the above embodiments can be used to design more complex resonators in the following embodiments.

[0050] In another embodiment, such as Figure 7 In the resonator structure with a hammerhead structure at the end of the first interdigital finger 11, the ends of the multiple first interdigital fingers 11 are respectively provided with protrusions 13; along the second direction, the length of the second busbar 20 is less than or equal to the length of the protrusions 13.

[0051] In this embodiment, the first interdigital finger 11 has a protrusion 13 (hammer head) at its end, which can suppress irregular vibrations at the end of the finger bar, making its vibration more stable. By making the length of the second busbar 20 less than or equal to the length of the protrusion 13, the second interdigital finger 21 has space to extend to correspond to the protrusion 13, effectively reflecting the sound waves suppressed by the protrusion 13, thereby improving the resonance effect of the resonator.

[0052] In another embodiment, such as Figure 8 , 9 The overlapping areas of the multiple first interdigitated fingers 11 are provided with a first dielectric structure 14 continuously or at intervals along the side extending in the first direction. The reflection unit is provided with a second dielectric structure 23 continuously or at intervals along the first direction corresponding to the first dielectric structure 14. A multiple second interdigitated fingers 21 extending in the second direction are provided between the two second busbars 20. The second dielectric structure 23 covers the second busbars 20 or covers a portion of the second busbars 20 and the second interdigitated fingers 21.

[0053] In this embodiment, by setting a first dielectric structure 14 on the side of the overlapping area of ​​the first interdigital fingers 11 in the aperture region of the active transducer unit, wave energy can be "constrained" within the overlapping area of ​​the interdigital fingers through acoustic impedance matching, reducing lateral leakage loss, thereby improving the Q value and fine-tuning the sound wave propagation characteristics. At the reflection unit, the corresponding second dielectric structure 23 has the same length as the first dielectric structure 14, and two forms of setting the second dielectric structure 23 are provided: First, when the length of the second busbar 20 is equal to that of the first dielectric structure 14 along the second direction Y, the second dielectric structure 23 covers the second busbar 20 at intervals or continuously (corresponding to the first dielectric structure 14 at intervals or continuously); Second, when the length of the second busbar 20 is less than that of the first dielectric structure 14, the second dielectric structure 23 covers the second busbar 20 at intervals or continuously and the connection portion of the second interdigital fingers 21 to the second busbar 20.

[0054] Of course, the second dielectric structure 23 may not be provided in the reflective unit. Those skilled in the art can flexibly choose the arrangement of the second dielectric structure 23 based on the improvements to the basic structure of the reflective unit in the embodiments of this application.

[0055] In another embodiment, such as Figure 10 The first busbar 10 is provided with a plurality of short truncated fingers 15 arranged alternately with the first interdigitated fingers 11, and the length of the second busbar 20 along the second direction Y is less than the length of the short truncated fingers 15 along the second direction Y.

[0056] In this embodiment, the acoustic energy excited by the first interdigit 11 tends to leak outwards towards the outside of the first busbar 10 (away from the interdigital overlap area), resulting in energy waste and a decrease in Q value. The presence of the truncated finger 15 can form a barrier near the busbar, and the local acoustic field it generates can block the main wave from spreading outwards, confining the energy within the interdigital overlap area, further optimizing the electric field distribution in the active region, reducing energy loss, and improving the stability of the resonator. Furthermore, the second busbar 20 is set to be smaller than the truncated finger 15, thereby extending the length of the second interdigit 21, expanding the reflection area, and preventing the second busbar 20 from being too long and affecting the function of the truncated finger 15.

[0057] In another embodiment, such as Figure 11 A plurality of first grid bars 16 are provided at intervals along the second direction between the overlapping areas of the first busbar 10 and the plurality of first interdigitated fingers 11. Each first grid bar 16 extends along the first direction and intersects with the plurality of first interdigitated fingers 11. Two adjacent second interdigitated fingers 21 are arranged alternately along the first direction. The ends of the plurality of second interdigitated fingers 21 located on the same straight line are connected to a second grid bar 24. The plurality of second grid bars 24 correspond in number to the plurality of first grid bars 16 and are arranged equally. The outermost second grid bar 24 is the second busbar 20.

[0058] In this embodiment, the active transducer unit extends along the X direction and is provided with multiple first grid strips 16 spaced apart in the Y direction. After intersecting with the first interdigitated fingers 11, they form multiple grids, which can play a role in uniformly distributing the electric field and suppressing energy leakage in the overlapping area and the part where the electric field is most concentrated between the first busbar 10. Correspondingly, in order to realize the formation of a stable standing wave between the reflector unit and the active transducer region, the second interdigitated fingers 21 are staggered and form grids of the same size as those in the active transducer region with the second grid strips 24. This not only extends the reflective surface but also improves the stability of the reflection rate.

[0059] This application also provides a surface acoustic wave filter, including the surface acoustic wave resonator as described in any of the preceding claims.

[0060] It also includes a bottom metal electrode layer 50, wherein the piezoelectric layer 40 is disposed on the bottom metal electrode layer 50, and the bottom metal electrode layer 50 is used to limit the spacing range of two adjacent resonators.

[0061] In this embodiment, the bottom metal electrode layer 50 serves as the common electrode for multiple resonators and is connected to external components. It can define the minimum safe distance between adjacent resonators based on its own electrical properties, so as to plan a more reasonable spatial layout of multiple resonators in the entire filter.

[0062] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A surface acoustic wave resonator, characterized in that, The system includes a piezoelectric layer (40), on the surface of which are provided active transducer units and reflective units; the active transducer units are provided with two first busbars (10) spaced apart, and the reflective units are provided with two second busbars (20) spaced apart; a first interval region (12) formed by the projection of the two first busbars (10) along a first direction covers a second interval region (22) formed by the projection of the two second busbars (20) along the first direction, and the length of the first interval region (12) along the second direction is greater than the length of the second interval region (22) along the second direction; the projection of the first busbar (10) along the second direction and the projection of the second busbar (20) along the second direction do not intersect; the first direction is perpendicular to the second direction; wherein, the inner sides of the two first busbars (10) are provided with a plurality of first interdigitated fingers (11) extending in opposite directions, and the plurality of first interdigitated fingers (11) are staggered along the first direction; the length of the overlapping area of ​​the plurality of first interdigitated fingers (11) along the second direction is equal to the length between the outer sides of the two second busbars (20) along the second direction; Among them, the overlapping areas of the multiple first interdigitated fingers (11) are provided with a first medium structure (14) continuously or intermittently on the side extending along the first direction, the reflection unit is provided with a second medium structure (23) continuously or intermittently on the first medium structure (14) along the first direction, and a multiple second interdigitated fingers (21) extending along the second direction are provided between the two second busbars (20), and the second medium structure (23) covers the second busbar (20) or covers the second busbar (20) and the second interdigitated fingers (21).

2. The surface acoustic wave resonator according to claim 1, characterized in that, It also includes a third busbar (30), which extends along a first direction and connects to the first busbar (10), wherein the first busbar (10) and the third busbar (30) intersect or completely overlap along the projection of the first direction.

3. The surface acoustic wave resonator according to claim 1, characterized in that, The length of the second busbar (20) along the second direction is less than the length of the first busbar (10) along the second direction.

4. The surface acoustic wave resonator according to claim 1, characterized in that, In the resonator structure with a hammerhead structure at the end of the first interdigital finger (11), the ends of the multiple first interdigital fingers (11) are respectively provided with protrusions (13); along the second direction, the length of the second busbar (20) is less than or equal to the length of the protrusions (13).

5. The surface acoustic wave resonator according to claim 1, characterized in that, The first busbar (10) has a plurality of short truncated fingers (15) arranged alternately with the first interdigitated fingers (11), and the length of the second busbar (20) along the second direction is less than the length of the short truncated fingers (15) along the second direction.

6. The surface acoustic wave resonator according to claim 1, characterized in that, Multiple first grid bars (16) are provided at intervals along the second direction between the overlapping areas of the first busbar (10) and the multiple first interdigitated fingers (11). Each first grid bar (16) extends along the first direction and intersects with the multiple first interdigitated fingers (11). Two adjacent second interdigitated fingers (21) are arranged alternately along the first direction. The ends of multiple second interdigitated fingers (21) located on the same straight line are connected to a second grid bar (24). The number of multiple second grid bars (24) corresponds to the number of multiple first grid bars (16) and they are arranged equally. The outermost second grid bar (24) is the second busbar (20).

7. A surface acoustic wave filter, characterized in that, Includes the surface acoustic wave resonator as described in any one of claims 1-6.

8. The surface acoustic wave filter according to claim 7, characterized in that, It also includes a bottom metal electrode layer (50), the piezoelectric layer (40) is disposed on the bottom metal electrode layer (50), the bottom metal electrode layer (50) is used to limit the spacing range of two adjacent resonators.

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