A surface acoustic wave resonator and filter

Abstract

The application discloses a surface acoustic wave resonator and filter, which comprises a substrate, a plurality of interdigital electrode groups located on one side of the substrate, the interdigital electrode group comprising a first electrode and a second electrode, the first electrode and the second electrode being arranged along a first direction and extending along the first direction, a gap being formed between the first electrode and the second electrode along the first direction, a plurality of load structure groups being located on one side of the substrate and in the gap, the load structure group comprising a first load structure and a second load structure arranged along the first direction, the first load structure being in contact with the first electrode, and the second load structure being in contact with the second electrode, the first load structure and the second load structure each comprising at least two sub-load structures arranged along the first direction, and the density of any two of the two sub-load structures in the same load structure and the electrode in contact with the sub-load structure being different. By adopting the above-mentioned means, the transverse mode can be suppressed by arranging the load structure group, and the Q value of the resonator is improved.

Description

Technical Field

[0001] This invention relates to the field of resonator technology, and more particularly to a surface acoustic wave resonator and filter. Background Technology

[0002] With the continuous development and application of communication technology, the requirements for radio frequency components are becoming increasingly stringent. As an important component of surface acoustic wave (SAW) filters, SAW resonators also face severe challenges. SAW filters need to have characteristics such as fast roll-off, low insertion loss, and low attenuation to meet market requirements.

[0003] The transverse resonant modes present in surface acoustic wave (SAW) resonators can interfere with the dominant mode, causing glitches in or out of the passband and affecting the Q value of the device. Currently, the conventional method to suppress transverse resonant modes is to thicken or widen the ends of the interdigital transducers to form a hammer structure. However, this method has limited effect on suppressing transverse resonant modes. Currently, transverse resonant modes can also be suppressed by tilting the electrodes, but this will reduce the Q value of the resonator. Summary of the Invention

[0004] This invention provides a surface acoustic wave resonator and filter to suppress transverse modes and improve the Q value of the resonator.

[0005] In a first aspect, embodiments of the present invention provide a surface acoustic wave resonator, comprising:

[0006] Substrate;

[0007] Multiple interdigitated electrode groups are located on one side of the substrate. Each interdigitated electrode group includes a first electrode and a second electrode. The first electrode and the second electrode are arranged along a first direction and both extend along the first direction. The extension length of the first electrode is less than the extension length of the second electrode. A gap is included between the first electrode and the second electrode along the first direction. The first direction is parallel to the plane of the substrate.

[0008] Multiple load structure groups are located on one side of the substrate and within the gap. Each load structure group includes a first load structure and a second load structure arranged along the first direction. The first load structure is in contact with the first electrode, and the second load structure is in contact with the second electrode. Both the first load structure and the second load structure include at least two sub-load structures arranged along the first direction. Furthermore, the densities of any two sub-load structures and the electrodes in contact with the sub-load structures in the same load structure are different.

[0009] Optionally, the first load structure includes a first sub-load structure and a second sub-load structure, wherein the first sub-load structure is in contact with the first electrode and the second sub-load structure respectively; the density of the first sub-load structure is less than the density of the first electrode, and the density of the second sub-load structure is greater than the density of the first electrode.

[0010] The second load structure includes a third sub-load structure and a fourth sub-load structure. The third sub-load structure is in contact with the second electrode and the fourth sub-load structure, respectively. The density of the third sub-load structure is less than the density of the second electrode, and the density of the fourth sub-load structure is greater than the density of the second electrode.

[0011] Optionally, the first load structure includes i sub-load structures; i ≥ 3, and i is an integer;

[0012] The density of the i-th sub-load structure is different from the density of the (i-1)-th sub-load structure;

[0013] The second load structure includes the j-th sub-load structure; j ≥ 3, and j is an integer;

[0014] The density of the j-th sub-load structure is different from the density of the (j-1)-th sub-load structure.

[0015] Optionally, at least two of the sub-load structures in the same load structure have the same length in the first direction.

[0016] Optionally, along the second direction, the dimension between any two adjacent first electrodes is the same as the dimension between any two adjacent second electrodes, and both are λ; the second direction intersects the first direction and is parallel to the plane containing the substrate;

[0017] Along the first direction, the length of the sub-load structure is L;

[0018] Where L = (2n+1)*(λ / 4), n≥0, and n is an integer.

[0019] Optionally, the width of any sub-load structure in the first load structure in the second direction is greater than or equal to the width of the first electrode;

[0020] The width of any sub-load structure in the second load structure in the second direction is greater than or equal to the width of the second electrode; the second direction intersects the first direction and is parallel to the plane of the substrate.

[0021] Optionally, the first load structure includes a first sub-load structure and a second sub-load structure, wherein the first sub-load structure is in contact with the first electrode and the second sub-load structure respectively; along the thickness direction of the surface acoustic wave resonator, the thickness of the second sub-load structure is greater than or equal to the thickness of the first sub-load structure.

[0022] The second load structure includes a third sub-load structure and a fourth sub-load structure. The third sub-load structure is in contact with the second electrode and the fourth sub-load structure, respectively. Along the thickness direction of the surface acoustic wave resonator, the thickness of the fourth sub-load structure is greater than or equal to the thickness of the third sub-load structure.

[0023] Optionally, along the thickness direction of the surface acoustic wave resonator, the surface of the first sub-load structure away from the substrate and the surface of the second sub-load structure away from the substrate are located on the same horizontal plane;

[0024] The surface of the third sub-load structure away from the substrate and the surface of the fourth sub-load structure away from the substrate are located on the same horizontal plane.

[0025] Optionally, the first electrode and the second electrode are alternately arranged along a second direction; the second direction intersects the first direction and is parallel to the plane of the substrate.

[0026] Secondly, embodiments of the present invention also provide a filter, including the surface acoustic wave resonator described in any of the first aspects.

[0027] The technical solution of this invention involves setting multiple load structure groups located in a gap. Each load structure group includes a first load structure and a second load structure. The first load structure is in contact with a first electrode, and the second load structure is in contact with a second electrode. Specifically, the first load structure is connected to the end of the first electrode, and the second load structure is connected to the end of the second electrode. Furthermore, both the first and second load structures include at least two sub-load structures arranged along a first direction. The densities of any two sub-load structures and the electrodes in contact with the sub-load structures within the same load structure are different. This creates a sound velocity difference when the surface acoustic wave propagates along the first direction, reflecting the leaked surface acoustic wave back to the active region, thereby improving the Q value of the resonator. Attached Figure Description

[0028] Figure 1 This is a top view schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present invention;

[0029] Figure 2 for Figure 1A schematic diagram of the cross-sectional structure of a surface acoustic wave resonator along section line A-A' is provided.

[0030] Figure 3 This is a schematic diagram of the admittance characteristic curve of a traditional surface acoustic wave resonator.

[0031] Figure 4 A schematic diagram of the admittance characteristic curve of a surface acoustic wave resonator provided in an embodiment of the present invention;

[0032] Figure 5 A top view schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention;

[0033] Figure 6 for Figure 1 A schematic diagram of the cross-sectional structure of another surface acoustic wave resonator along section line A-A' is provided. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0035] Figure 1 This is a top view schematic diagram of a surface acoustic wave resonator provided in an embodiment of the present invention. Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure of a surface acoustic wave resonator along section line A-A' is provided, as shown below. Figure 1 and Figure 2 As shown, the surface acoustic wave resonator includes: a substrate 10; a plurality of interdigitated electrode groups 20 located on one side of the substrate 10, each interdigitated electrode group 20 including a first electrode 201 and a second electrode 202, the first electrode 201 and the second electrode 202 being arranged along a first direction (X direction as shown in the figure) and both extending along the first direction X, the extension length of the first electrode 201 being less than the extension length of the second electrode 202; a gap 30 being included between the first electrode 201 and the second electrode 202 along the first direction X; the first direction X being parallel to the plane of the substrate 10; and a plurality of loads. The structure group 40 is located on one side of the substrate 10 and within the gap 30. The load structure group 40 includes a first load structure 401 and a second load structure 402 arranged along the first direction X. The first load structure 401 is in contact with the first electrode 201, and the second load structure 402 is in contact with the second electrode 202. Both the first load structure 401 and the second load structure 402 include at least two sub-load structures 41 arranged along the first direction X. The densities of the two sub-load structures 41 and the electrodes in contact with the sub-load structures 41 in the same load structure are different.

[0036] Specifically, substrate 10 can be a piezoelectric substrate. For example, the material of substrate 10 can be lithium niobate, lithium tantalate, zinc oxide, aluminum nitride, gallium nitride, or barium titanate, etc.

[0037] Specifically, the interdigitated electrode group 20 includes a first electrode 201 and a second electrode 202. The first electrode 201 and the second electrode 202 are arranged along a first direction X and both extend along the first direction X. Along the first direction X, the extension length of the first electrode 201 is less than the extension length of the second electrode 202. That is, the first electrode 201 can be a pseudo-finger electrode, i.e., a short finger electrode, and the second electrode 202 can be a true finger electrode, i.e., a long finger electrode. For example, the materials of the first electrode 201 and the second electrode 202 can both be metal materials such as copper, aluminum, titanium, tungsten, or silver. Specifically, the first electrode 201 and the second electrode 202 are alternately arranged along a second direction (the Y direction shown in the figure); the second direction Y intersects the first direction X and is parallel to the plane where the substrate 10 is located.

[0038] Furthermore, when an AC signal of a certain frequency is applied to the busbar 50, surface acoustic waves (SAWs) can be generated in the SAW resonator. The SAWs are mainly concentrated in the effective aperture region, i.e., the active region, and mainly propagate along the second direction Y. However, some transverse waves also propagate and leak along the first direction X towards the busbar 50. The active region can be understood as the area where the second electrodes 202 overlap.

[0039] Specifically, along the first direction X, a gap 30 is included between the first electrode 201 and the second electrode 202. The surface acoustic wave resonator also includes multiple load structure groups 40, which are located on one side of the substrate 10 and within the gap 30. The load structure group 40 includes a first load structure 401 and a second load structure 402 arranged along the first direction X. The first load structure 401 is in contact with the first electrode 201, and the second load structure 402 is in contact with the second electrode 202. That is, the first load structure 401 is in contact with the end of the first electrode 201, and the second load structure 402 is in contact with the end of the second electrode 202.

[0040] Furthermore, both the first load structure 401 and the second load structure 402 include at least two sub-load structures 41 arranged along the first direction X; and the densities of any two sub-load structures 41 and the electrodes in contact with the sub-load structures 41 in the same load structure are different. In other words, the densities of the two sub-load structures 41 in the first load structure 401 are different from those of any two in the first electrode 201, and the densities of the two sub-load structures 41 in the second load structure 402 are different from those of any two in the second electrode 202. It is understandable that, since the mass of the sub-load structure 41 is proportional to its density, and the force exerted by the sub-load structure 41 on the substrate 10 is related to the mass of the sub-load structure 41, that is, the greater the mass of the sub-load structure 41, the greater the force exerted on the substrate 10, and the slower the propagation speed of the surface acoustic wave in this region, by setting two sub-load structures 41 in the same load structure and the electrodes in contact with the sub-load structure 41, the densities of any two are different. This is beneficial to ensure that there is a sound speed difference when the surface acoustic wave propagates along the first direction X, so that the surface acoustic wave can be reflected back to the active region, that is, the suppression of the transverse mode can be achieved.

[0041] For example, when the first load structure 401 includes two sub-load structures 41, the first sub-load structure 411 is in contact with the first electrode 201 and the second sub-load structure 412 respectively. The density of the two sub-load structures 41 is different from that of the first electrode 201. Thus, when the surface acoustic wave propagates along the first direction X, due to the difference in sound velocity, it will be reflected at the interface between the first electrode 201 and the first sub-load structure 411. When it continues to propagate along the first direction X, it will be reflected at the interface between the first sub-load structure 411 and the second sub-load structure 412, thereby reflecting the surface acoustic wave propagating along the first direction X back to the active region and suppressing the leakage of the surface acoustic wave in the first direction X.

[0042] The surface acoustic wave (SAW) resonator provided in this embodiment of the invention utilizes multiple load structure groups located in a gap. Each load structure group includes a first load structure and a second load structure. The first load structure contacts a first electrode, and the second load structure contacts a second electrode; that is, the first load structure is connected to the end of the first electrode, and the second load structure is connected to the end of the second electrode. Furthermore, both the first and second load structures include at least two sub-load structures arranged along a first direction. The densities of any two sub-load structures and the electrodes in contact with the sub-load structures within the same load structure are different. This creates a sound velocity difference when the SAW propagates along the first direction, reflecting the leaked SAW back to the active region, thereby improving the Q value of the resonator.

[0043] Optional, continue to refer to Figure 1 and Figure 2The first load structure 401 includes a first sub-load structure 411 and a second sub-load structure 412. The first sub-load structure 401 is in contact with the first electrode 201 and the second sub-load structure 402, respectively. The density of the first sub-load structure 401 is less than the density of the first electrode 201, and the density of the second sub-load structure 412 is greater than the density of the first electrode 201. The second load structure 402 includes a third sub-load structure 413 and a fourth sub-load structure 414. The third sub-load structure 413 is in contact with the second electrode 202 and the fourth sub-load structure 414, respectively. The density of the third sub-load structure 413 is less than the density of the second electrode 202, and the density of the fourth sub-load structure 414 is greater than the density of the second electrode 202.

[0044] Specifically, the first sub-load structure 411 is in contact with both the first electrode 201 and the second sub-load structure 412. That is, the first sub-load structure 411 is located between the first electrode 201 and the second sub-load structure 412, and the first electrode 201, the first sub-load structure 411, and the second sub-load structure 412 are in contact with each other. Furthermore, the density of the first sub-load structure 411 is less than the density of the first electrode 201, and the density of the second sub-load structure 412 is greater than the density of the first electrode 201. This means that the sound velocity in the piezoelectric substrate 10 region covered by the first electrode 201 is less than the sound velocity in the piezoelectric substrate 10 region covered by the first sub-load structure 411, but greater than the sound velocity in the piezoelectric substrate 10 region covered by the second sub-load structure 412. Thus, when the surface acoustic wave propagates along the first direction X, a significant sound velocity difference is generated, which can suppress transverse modes and improve the Q value of the resonator.

[0045] Specifically, the third sub-load structure 413 is in contact with both the second electrode 202 and the third sub-load structure 413. That is, the third sub-load structure 413 is located between the second electrode 202 and the third sub-load structure 413, and the second electrode 202, the third sub-load structure 413, and the fourth sub-load structure 414 are in contact. Furthermore, the density of the third sub-load structure 413 is less than the density of the second electrode 202, and the density of the fourth sub-load structure 414 is greater than the density of the second electrode 202. This means that the sound velocity in the piezoelectric substrate 10 region covered by the second electrode 202 is less than the sound velocity in the piezoelectric substrate 10 region covered by the third sub-load structure 413, but greater than the sound velocity in the piezoelectric substrate 10 region covered by the fourth sub-load structure 414. Thus, when the surface acoustic wave propagates along the first direction X, a significant sound velocity difference is generated, which can suppress transverse modes and improve the Q value of the resonator.

[0046] It should be noted that, Figure 1Only the technical solution shown is that the density of the first sub-load structure 411 is equal to the density of the third sub-load structure 413, and the density of the second sub-load structure 412 is equal to the density of the fourth sub-load structure 414. Using this technical solution, the suppression effect of the embodiment of the present invention on the transverse mode can be determined by finite element simulation based on the obtained admittance characteristic curve. Specifically... Figure 3 This is a schematic diagram of the admittance characteristic curve of a traditional surface acoustic wave resonator. Figure 4 This is a schematic diagram of the admittance characteristic curve of a surface acoustic wave resonator provided in an embodiment of the present invention, as shown below. Figure 3 and Figure 4 As shown, a traditional surface acoustic wave resonator can be understood as a resonator without a load structure. (Refer to...) Figure 3 Curves a' and b' in the figure represent the admittance characteristic curve and phase response curve of a conventional surface acoustic wave resonator, respectively. Between the resonance peak and the anti-resonance peak, the fluctuations in curves a' and b' are quite pronounced. However, referring to... Figure 4 Curves a and b in the figure are the admittance characteristic curve and phase response curve of the surface acoustic wave resonator provided in the embodiment of the present invention, respectively. Between the resonance peak and the anti-resonance peak, curves a and b are relatively smooth and have small fluctuations. It can be seen that the technical solution provided in the embodiment of the present invention can effectively suppress the transverse mode and improve the performance of the resonator.

[0047] It is understandable that the densities of the first sub-load structure 411, the second sub-load structure 412, the third sub-load structure 413, and the fourth sub-load structure 414 can all be different.

[0048] For example, the metal combination of the first sub-load structure and the second sub-load structure can be gold and aluminum, copper and aluminum, nickel and aluminum, chromium and nickel, silver and copper, gold and copper, platinum and aluminum, palladium and aluminum, or titanium and aluminum, etc.

[0049] Optional, Figure 5 A top view schematic diagram of another surface acoustic wave resonator provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the first load structure 401 includes i sub-load structures 41; i ≥ 3, and i is an integer; the density of the i-th sub-load structure is different from the density of the (i-1)-th sub-load structure; the second load structure 402 includes j-th sub-load structure 41; j ≥ 3, and j is an integer; the density of the j-th sub-load structure is different from the density of the (j-1)-th sub-load structure.

[0050] Specifically, the first load structure 401 includes i sub-load structures 41; i ≥ 3, and i is an integer, meaning the first load structure 401 includes at least 3 sub-load structures 41. The density of the i-th sub-load structure is different from the density of the (i-1)-th sub-load structure, meaning the densities of two adjacent sub-load structures 41 are different. Thus, when the surface acoustic wave propagates along the first direction X, there is a sound velocity difference, which can reflect the surface acoustic wave leaking along the first direction X back to the active region, thereby improving the Q value of the resonator.

[0051] For example, when i=3, the first load structure 401 includes three sub-load structures, namely the first sub-load structure 411, the second sub-load structure 412, and the sub-load structure 415. The sub-load structure 415 can be understood as the load structure in the first load structure 401 that is in contact with the second sub-load structure 412. The density of the sub-load structure 415 is different from that of the second sub-load structure 412. In this way, the surface acoustic wave will generate multiple sound velocity differences when it propagates along the first direction X, which can improve the reflectivity and reflect more surface acoustic waves propagating along the first direction X back to the active region, thereby improving the Q value of the resonator.

[0052] Specifically, the second load structure 402 includes j sub-load structures 41; j ≥ 3, and j is an integer, meaning the second load structure 402 includes at least 3 sub-load structures 41. The density of the j-th sub-load structure is different from that of the (j-1)-th sub-load structure, meaning that the densities of two adjacent sub-load structures 41 are different. Thus, when the surface acoustic wave propagates along the first direction X, there is a sound velocity difference, which can reflect the surface acoustic wave leaking along the first direction X back to the active region, thereby improving the Q value of the resonator.

[0053] For example, when i=3, the second load structure 402 includes three sub-load structures 41, namely the third sub-load structure 413, the fourth sub-load structure 414, and the sub-load structure 416. The sub-load structure 416 can be understood as a load structure in contact with the fourth sub-load structure 414. The density of the sub-load structure 416 is different from that of the fourth sub-load structure 414. In this way, the surface acoustic wave will generate multiple sound velocity differences when it propagates along the first direction X, which can improve the reflectivity and reflect more surface acoustic waves propagating along the first direction X back to the active region, thereby improving the Q value of the resonator.

[0054] For example, the first load structure 401 may also include four sub-load structures. The arrangement of the sub-load structures in the first load structure 401 may be "first sub-load structure - second sub-load structure - first sub-load structure - second sub-load structure". In this way, the surface acoustic wave will generate multiple sound velocity differences when it propagates along the first direction X, which can improve the reflectivity and reflect more surface acoustic waves propagating along the first direction X back to the active region, thereby improving the Q value of the resonator. In addition, the arrangement is simple and does not require the use of multiple metal materials with different densities.

[0055] Optional, continue to refer to Figure 1 At least two sub-load structures 41 in the same load structure have the same length in the first direction X.

[0056] For example, taking the first load structure 401 as an example, when the first load structure 401 includes a first sub-load structure 411 and a second sub-load structure 412, along the first direction X, the length of the first sub-load structure 411 is equal to the length of the second sub-load structure 412.

[0057] Further reference Figure 1 Along the second direction Y, the dimension between any two adjacent first electrodes 201 is the same as the dimension between any two adjacent second electrodes 202 and both are λ; the second direction Y intersects the first direction X and is parallel to the plane where the substrate 10 is located; along the first direction X, the length of the sub-load structure 41 is L; where L=(2n+1)*(λ / 4), n≥0, and n is an integer.

[0058] Specifically, L = (2n+1)*(λ / 4), meaning the length L of the sub-load structure 41 is an odd multiple of (λ / 4). Since the shape of a surface acoustic wave (SAW) is similar to a sine wave, for example, when one period of the SAW is λ, L = λ / 4 or L = 3*(λ / 4). The reflected sound wave and the incident sound wave are out of phase by λ / 2, meaning their vibration directions are completely opposite. Therefore, the reflected sound wave and the incident sound wave will form crests and troughs that cancel each other out, weakening or even eliminating the sound wave. Thus, energy can be concentrated in the sound wave propagating in the active region, further suppressing the transverse mode and improving the Q value of the resonator.

[0059] Optional, continue to refer to Figure 1 The width of any sub-load structure 41 in the first load structure 401 in the second direction Y is greater than or equal to the width of the first electrode 201; the width of any sub-load structure 41 in the second load structure 402 in the second direction Y is greater than or equal to the width of the second electrode 202; the second direction Y intersects the first direction X and is parallel to the plane where the substrate 10 is located.

[0060] Specifically, taking the first load structure 401 as an example, the width of each load structure 41 in the first load structure 401 in the second direction Y can be the same or different. For example, the width of each load structure 41 in the first load structure 401 in the second direction Y can be equal to the width of the first electrode 201, or the width of any sub-load structure 41 in the first load structure 401 in the second direction Y can be greater than the width of the first electrode 201. That is, the first electrode 201 and the first load structure 401 form a "hammer shape". In this way, on the one hand, the lateral mode can be suppressed by setting the first load structure, and on the other hand, the diversified settings of the load structure can be realized.

[0061] Optional, Figure 6 for Figure 1 Another schematic diagram of the cross-sectional structure of a surface acoustic wave resonator along section line A-A' is provided below. (Continue to refer to...) Figure 1 Figure 2 and Figure 4 The first load structure 401 includes a first sub-load structure 411 and a second sub-load structure 412. The first sub-load structure 411 is in contact with the first electrode 201 and the second sub-load structure 412, respectively. Along the thickness direction of the surface acoustic wave resonator (Z direction as shown in the figure), the thickness of the second sub-load structure 402 is greater than or equal to the thickness of the first sub-load structure 401. The second load structure 402 includes a third sub-load structure 413 and a fourth sub-load structure 414. The third sub-load structure 413 is in contact with the second electrode 202 and the fourth sub-load structure 414, respectively. Along the thickness direction Z of the surface acoustic wave resonator, the thickness of the fourth sub-load structure 414 is greater than or equal to the thickness of the third sub-load structure 413.

[0062] Specifically, taking the first load structure 401 as an example, when the first load structure 401 includes a first sub-load structure 411 and a second sub-load structure 412, as a feasible implementation, the thickness of the second sub-load structure 402 can be equal to the thickness of the first sub-load structure 401. Furthermore, along the thickness direction Z of the surface acoustic wave resonator, the surface of the first sub-load structure 411 away from the substrate 10 and the surface of the second sub-load structure 412 away from the substrate 10 are located on the same horizontal plane. This ensures that the upper surfaces of the first sub-load structure 411 and the second sub-load structure 412 are flush, which is beneficial to ensuring the flatness of the resonator surface. As another feasible implementation, the thickness of the second sub-load structure 402 can be greater than the thickness of the first sub-load structure 401. Furthermore, along the thickness direction Z of the surface acoustic wave resonator, the surface of the first sub-load structure 411 away from the substrate 10 and the surface of the second sub-load structure 412 away from the substrate 10 are located on the same horizontal plane. That is, the thickness of the second sub-load structure 412 is greater than the thickness of the first sub-load structure 411, and their upper surfaces are flush. This allows for selective etching of the substrate 10 corresponding to the second sub-load structure 412 to deposit the second sub-load structure 412 in the etched area. This ensures that the second sub-load structure 412 has a larger thickness, thereby further reducing the sound velocity in the region corresponding to the second sub-load structure 412 and ensuring a large sound velocity difference between the region corresponding to the first sub-load structure 411 and the region corresponding to the second sub-load structure 412, thus improving the suppression effect on the transverse mode. In addition, by setting the upper surfaces of the first sub-load structure 411 and the second sub-load structure 412 to be flush, it is beneficial to ensure the flatness of the resonator surface.

[0063] Specifically, along the thickness direction Z of the surface acoustic wave resonator, the thickness of the fourth sub-load structure 414 is greater than or equal to the thickness of the third sub-load structure 413. Furthermore, the surface of the third sub-load structure 413 away from the substrate 10 and the surface of the fourth sub-load structure 414 away from the substrate 10 are located on the same horizontal plane. This further suppresses transverse modes and helps ensure the flatness of the resonator surface.

[0064] In summary, the surface acoustic wave resonator provided in this embodiment of the invention, by setting multiple load structure groups located in the gap, includes a first load structure and a second load structure. The first load structure is in contact with a first electrode, and the second load structure is in contact with a second electrode. That is, the first load structure is connected to the end of the first electrode, and the second load structure is connected to the end of the second electrode. Furthermore, both the first load structure and the second load structure include at least two sub-load structures arranged along a first direction; and the densities of any two sub-load structures and the electrodes in contact with the sub-load structures in the same load structure are different. Thus, when the surface acoustic wave propagates along the first direction, there is a sound velocity difference, which can reflect the surface acoustic wave leaking along the first direction back to the active region, thereby improving the Q value of the resonator.

[0065] Based on the same inventive concept, this embodiment of the invention also provides a filter, including the surface acoustic wave resonator in the above embodiments. Therefore, the filter provided by this embodiment of the invention also has the beneficial effects described in the above embodiments, which will not be repeated here.

[0066] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A surface acoustic wave resonator, characterized by, The application relates to a surface acoustic wave resonator, comprising: a substrate; a plurality of interdigital electrode groups on one side of the substrate, each of the interdigital electrode groups comprising a first electrode and a second electrode, the first electrode and the second electrode being arranged along a first direction and extending along the first direction, the first electrode having a length of extension smaller than that of the second electrode, and a gap being formed between the first electrode and the second electrode along the first direction, the first direction being parallel to the plane of the substrate; a plurality of load structure groups on one side of the substrate and in the gap, each of the load structure groups comprising a first load structure and a second load structure arranged along the first direction, the first load structure being in contact with the first electrode and the second load structure being in contact with the second electrode, each of the first load structure and the second load structure comprising at least two sub-load structures arranged along the first direction, and the density of any two of the two sub-load structures in the same load structure and the electrode in contact with the sub-load structures being different; wherein the first load structure comprises a first sub-load structure and a second sub-load structure, the first sub-load structure being in contact with the first electrode and the second sub-load structure respectively, the density of the first sub-load structure being smaller than that of the first electrode, and the density of the second sub-load structure being greater than that of the first electrode; the second load structure comprises a third sub-load structure and a fourth sub-load structure, the third sub-load structure being in contact with the second electrode and the fourth sub-load structure respectively, the density of the third sub-load structure being smaller than that of the second electrode, and the density of the fourth sub-load structure being greater than that of the second electrode.

2. The surface acoustic wave resonator according to claim 1, characterized by the first load structure comprises i sub-load structures; i>=3, and i is an integer; the density of the i-th sub-load structure is different from that of the (i-1)-th sub-load structure; the second load structure comprises a j-th sub-load structure; j>=3, and j is an integer; the density of the j-th sub-load structure is different from that of the (j-1)-th sub-load structure.

3. The surface acoustic wave resonator according to claim 1, wherein the lengths of at least two sub-load structures in the same load structure along the first direction are the same.

4. The surface acoustic wave resonator according to claim 3, wherein along a second direction, the size between any two adjacent first electrodes is the same as that between any two adjacent second electrodes and is equal to lambda; the second direction intersects the first direction and is parallel to the plane of the substrate; the length of the sub-load structure along the first direction is L; wherein L=(2n+1)*(lambda / 4), n>=0, and n is an integer.

5. The surface acoustic wave resonator of claim 1, wherein, the width of any sub-load structure in the first load structure along a second direction is greater than or equal to the width of the first electrode; the width of any sub-load structure in the second load structure along the second direction is greater than or equal to the width of the second electrode; the second direction intersects the first direction and is parallel to the plane of the substrate.

6. The surface acoustic wave resonator of claim 1, wherein, along the thickness direction of the surface acoustic wave resonator, the thickness of the second sub-load structure is greater than or equal to that of the first sub-load structure. The fourth sub-load structure has a thickness greater than or equal to a thickness of the third sub-load structure along a thickness direction of the surface acoustic wave resonator.

7. The surface acoustic wave resonator according to claim 6, wherein The first sub-load structure has a surface away from the substrate at a same horizontal plane as a surface of the second sub-load structure away from the substrate along a thickness direction of the surface acoustic wave resonator. The third sub-load structure has a surface away from the substrate at a same horizontal plane as a surface of the fourth sub-load structure away from the substrate.

8. The surface acoustic wave resonator of claim 1, wherein, The first electrode and the second electrode are alternately arranged along a second direction, the second direction intersects the first direction and is parallel to a plane on which the substrate is located.

9. A filter, characterized by The surface acoustic wave resonator of any one of claims 1-8.

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