A surface acoustic wave resonator

Abstract

The application discloses a surface acoustic wave resonator, comprising a piezoelectric substrate and an interdigital transducer arranged on the piezoelectric substrate. The interdigital transducer comprises a first bus bar and a second bus bar arranged in parallel, a first thickening layer arranged vertically above the first bus bar and a second thickening layer arranged vertically above the second bus bar. The first end of the first thickening layer is aligned with the end of the first bus bar away from the second bus bar, and the second end of the second thickening layer is aligned with the end of the second bus bar away from the first bus bar. The interdigital transducer further comprises a first compensation layer arranged vertically above the first bus bar and a second compensation layer arranged vertically above the second bus bar, and the third end of the first compensation layer is aligned with the end of the first bus bar close to the second bus bar, and the fourth end of the second compensation layer is aligned with the end of the second bus bar close to the first bus bar.

Description

Technical Field

[0001] This application relates to the field of surface acoustic wave (SAW) devices, and in particular to a SAW resonator. Background Technology

[0002] As 5G communication evolves towards higher frequencies and wider bandwidths, surface acoustic wave (SAW) resonators based on piezoelectric thin films (such as POI substrates) have become a key technology due to their high Q-value and high coupling coefficient. However, due to the inherent strong acoustic waveguide effect of the thin film structure, acoustic wave energy is highly concentrated within the thin film layer. This makes it easier for energy to form parasitic standing waves, i.e., transverse modes, within the SAW resonator aperture along the direction perpendicular to the main propagation. These transverse modes introduce spurious peaks into the spectrum, affecting the passband flatness, out-of-band rejection, and insertion loss of the filter, ultimately degrading the overall performance of the filter.

[0003] Existing methods for suppressing transverse modes involve adding a mass load to the busbars of the interdigital transducer, thereby reducing the acoustic wave propagation velocity in the busbar region. This allows the transverse modes to leak out through the busbars, thus suppressing them in the surface acoustic wave resonator.

[0004] However, when a mass load is added to the busbar, due to process limitations (such as photolithography and etching), the actual width of the mass load will be smaller than the design value, resulting in inward shrinkage. This affects the ability to suppress transverse modes and thus reduces the resonance performance of the surface acoustic wave resonator.

[0005] The publication number is CN120415366A, and the title is "Surface Acoustic Wave Resonator and Electronic Device." The interdigital transducer includes two opposing outer busbars and at least two opposing inner busbars, with the inner busbars positioned between the outer busbars. Both the outer and inner busbars are parallel to their length direction. Each inner busbar has multiple first protrusions extending along its width and length direction, forming an inner edge sound velocity region on at least one side of the inner busbar. The sound velocity in the inner edge sound velocity region is lower than that in the inner layer sound velocity region. The sawtooth structure formed by the multiple first protrusions causes diffuse reflection of sound waves during transverse propagation, thereby reducing the Q value of transverse clutter modes and effectively suppressing the generation of transverse modes.

[0006] The publication number is CN119628595A, and the title is "A Surface Acoustic Wave Resonator and Filter." It includes: an interdigitated structure comprising a first interdigitated region and a second interdigitated region; the first interdigitated region includes multiple first finger strips, and the second interdigitated region includes multiple second finger strips; a reflective grating, disposed on both sides of the interdigitated structure in a first direction, the reflective grating, the multiple first finger strips, and the multiple second finger strips being located in the same plane; the reflective grating intersects perpendicularly with the multiple first finger strips, and the reflective grating intersects perpendicularly with the multiple second finger strips; in the first direction, each first finger strip and each second finger strip are arranged opposite to each other, with a gap forming between the first and second finger strips; in a second direction, the multiple first finger strips are arranged in parallel, and the multiple second finger strips are arranged in parallel; the first direction and the second direction are perpendicular.

[0007] There is currently no effective solution to the technical problem in the prior art where the transverse modes in the surface acoustic wave resonator are not effectively suppressed, thus affecting the performance of the surface acoustic wave resonator. Summary of the Invention

[0008] This disclosure provides a surface acoustic wave resonator to at least solve the technical problem in the prior art where the transverse mode is not effectively suppressed, thus affecting the performance of the surface acoustic wave resonator.

[0009] According to one aspect of this application, a surface acoustic wave (SAW) resonator is provided, including a piezoelectric substrate and an interdigital transducer disposed on the piezoelectric substrate. The interdigital transducer includes a first busbar and a second busbar arranged in parallel, a first thickened layer disposed vertically above the first busbar, and a second thickened layer disposed vertically above the second busbar. A first end of the first thickened layer is aligned with the end of the first busbar away from the second busbar, and a second end of the second thickened layer is aligned with the end of the second busbar away from the first busbar. The interdigital transducer further includes a first compensation layer disposed vertically above the first busbar and a second compensation layer disposed vertically above the second busbar, with a third end of the first compensation layer aligned with the end of the first busbar near the second busbar, and a fourth end of the second compensation layer aligned with the end of the second busbar near the first busbar.

[0010] To address the technical problem that the ineffective suppression of transverse modes in surface acoustic wave (SAW) resonators affects their performance, this application provides a SAW resonator. This SAW resonator has a first thickened layer on a first busbar and a second thickened layer on a second busbar.

[0011] Furthermore, this application also deposits a first compensation layer on the first busbar. The first compensation layer is disposed parallel to the first thickening layer, and the first compensation layer and the first thickening layer together cover the first busbar. Therefore, even when the first thickening layer is deposited using photolithography and etching techniques, and a portion of the upper surface of the first busbar is exposed due to the shrinkage of the first thickening layer, the first compensation layer can still cover the exposed portion of the first busbar. This ensures that the first thickening layer and the first compensation layer together act as a mass load to completely cover the first busbar.

[0012] Similarly, this application also deposits a second compensation layer on the second busbar. The second compensation layer is disposed parallel to the second thickened layer, and the second compensation layer and the second thickened layer together cover the second busbar. Therefore, even when the second thickened layer is deposited using photolithography and etching techniques, and a portion of the upper surface of the second busbar is exposed due to the shrinkage of the second thickened layer, the second compensation layer can still cover the exposed portion of the second busbar. This ensures that the second thickened layer and the second compensation layer together act as a mass load to completely cover the second busbar.

[0013] Therefore, the above structure can compensate for the shrinkage of the first and second thickened layers caused by the manufacturing process, allowing the first and second busbars to be completely covered by the mass load. Consequently, the transverse modes in the surface acoustic wave resonator are effectively suppressed, improving the performance of the surface acoustic wave resonator.

[0014] Furthermore, compared to existing transverse mode suppression techniques, this application has a simpler structure, a larger process window, and is less susceptible to process limitations; and it has a smaller impact on the Q value of the surface acoustic wave resonator.

[0015] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments of this application in conjunction with the accompanying drawings. Attached Figure Description

[0016] The following sections will describe some specific embodiments of this application in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0017] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave resonator according to an embodiment of this application;

[0018] Figure 2 This is a comparison diagram of lateral pattern suppression of the first thickened layer and the second thickened layer under different inward distances according to the embodiments of this application;

[0019] Figure 3This is a comparison curve of the sound velocity of an interdigital transducer made of aluminum and an interdigital transducer made of copper under different duty cycles, according to the embodiments of this application.

[0020] Figure 4 These are comparative images showing the suppression of lateral modes when the busbar, thickened layer, and compensation layer are made of gold, platinum, chromium, cobalt, and aluminum, according to embodiments of this application.

[0021] Figure 5 This is a schematic diagram of another surface acoustic wave resonator according to this application. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] To enable those skilled in the art to better understand the present disclosure, the technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present disclosure.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate for the embodiments of this disclosure 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 apparatus 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 apparatus.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Figure 1 This is a schematic diagram of the surface acoustic wave resonator according to this embodiment. Figure 2This is a comparison diagram of lateral mode suppression of the first and second thickened layers under different inward reduction distances according to this embodiment. According to one aspect of this embodiment, a surface acoustic wave resonator is provided, including a piezoelectric substrate 100 and an interdigital transducer 200 disposed on the piezoelectric substrate 100. The interdigital transducer 200 includes a first busbar 210 and a second busbar 220 disposed in parallel, and a first thickened layer 211 disposed vertically above the first busbar 210 and a second thickened layer 221 disposed vertically above the second busbar 220, respectively. The first end 2111 of the first thickened layer 211 is aligned with the end of the first busbar 210 away from the second busbar 220, and the second end 2211 of the second thickened layer 221 is aligned with the end of the second busbar 220 away from the first busbar 210. The interdigital transducer 200 also includes a first compensation layer 212 disposed vertically above the first busbar 210 and a second compensation layer 222 disposed vertically above the second busbar 220. The third end 2121 of the first compensation layer 212 is aligned with the end of the first busbar 210 near the second busbar 220, and the fourth end 2221 of the second compensation layer 222 is aligned with the end of the second busbar 220 near the first busbar 210.

[0027] Specifically, refer to Figure 1 As shown, the surface acoustic wave resonator includes an interdigital transducer 200 located on a piezoelectric substrate 100. The interdigital transducer 200 includes a first busbar 210 and a second busbar 220 arranged opposite to and parallel to each other. The surface acoustic wave resonator also includes a first thickened layer 211 vertically above the first busbar 210 and a second thickened layer 221 vertically above the second busbar 220. The first end 2111 of the first thickened layer 211 is aligned with the end of the first busbar 210 away from the second busbar 220, and the second end 2211 of the second thickened layer 221 is aligned with the end of the second busbar 220 away from the first busbar 210.

[0028] While existing technology incorporates a first thickened layer 211 and a second thickened layer 221 for suppressing lateral modes on the first busbar 210 and the second busbar 220, limitations in fabrication processes such as photolithography and etching result in a shrinkage of the first and second thickened layers 211 and 221. Consequently, the width of the first thickened layer 211 is smaller than the width of the first busbar 210, and the width of the second thickened layer 221 is smaller than the width of the second busbar 220. In other words, the first and second busbars 210 and 220 are not completely covered by the mass load (i.e., the first and second thickened layers 211 and 221), which affects the ability to suppress lateral modes of the surface acoustic wave resonator.

[0029] Specifically, refer to Figure 2As shown, when the inward distance between the first thickened layer 211 and the first busbar 210 is 0~1μm and the inward distance between the second thickened layer 221 and the second busbar 220 is 0~1μm, the ability to suppress the transverse modes of the surface acoustic wave resonator decreases slightly; while when the inward distance between the first thickened layer 211 and the first busbar 210 is 1~3μm and the inward distance between the second thickened layer 221 and the second busbar 220 is 1~3μm, the ability to suppress the transverse modes of the surface acoustic wave resonator decreases sharply.

[0030] To address the aforementioned issues, this application further includes a first compensation layer 212 vertically above the first busbar 210 and a second compensation layer 222 vertically above the second busbar 220. Furthermore, the third end 2121 of the first compensation layer 212 is aligned with the end of the first busbar 210 near the second busbar 220, and the fourth end 2221 of the second compensation layer 222 is aligned with the end of the second busbar 220 near the first busbar 210.

[0031] Therefore, even if the first thickened layer 211 shrinks during fabrication using processes such as deposition or photolithography, the first compensation layer 212 can compensate for the exposed upper surface of the first busbar 210 caused by the shrinkage. In other words, the first thickened layer 211 and the first compensation layer 212 together act as a mass load, completely covering the first busbar 210.

[0032] Similarly, even if the second thickened layer 221 shrinks during fabrication using processes such as deposition or photolithography, the second compensation layer 222 can compensate for the exposed upper surface of the second busbar 220 caused by the shrinkage. In other words, the second thickened layer 221 and the second compensation layer 222 together act as a mass load, completely covering the second busbar 220.

[0033] This solves the problem of decreased transverse mode suppression capability caused by the inward shrinkage of the first thickened layer 211 and the second thickened layer 221. Consequently, the transverse modes of the surface acoustic wave resonator are effectively suppressed, thus avoiding performance degradation.

[0034] As described in the background section, with the development of 5G communication towards higher frequencies and wider bandwidths, surface acoustic wave (SAW) resonators based on piezoelectric thin films (such as POI substrates) have become a key technology due to their high Q-value and high coupling coefficient. However, due to the inherent strong acoustic waveguide effect of the thin film structure, acoustic wave energy is highly concentrated within the thin film layer, making it easier for energy to form parasitic standing waves, i.e., transverse modes, within the SAW resonator aperture along the direction perpendicular to the main propagation. These transverse modes introduce spurious peaks into the spectrum, affecting the passband flatness, out-of-band rejection, and insertion loss of the filter, ultimately degrading the overall performance of the filter. Existing methods for suppressing transverse modes involve adding a mass load to the busbar of the interdigital transducer to reduce the acoustic wave propagation speed in the busbar region. This allows the transverse modes to leak out through the busbar, thereby suppressing them in the SAW resonator. However, when adding a mass load to the busbar, due to process limitations (e.g., photolithography and etching), the actual width of the mass load is smaller than the design value, resulting in inward shrinkage, which affects the ability to suppress transverse modes and thus reduces the resonant performance of the SAW resonator.

[0035] In view of this, this application provides a surface acoustic wave (SAW) resonator. The SAW resonator has a first thickened layer on a first busbar and a second thickened layer on a second busbar. Furthermore, this application also deposits a first compensation layer on the first busbar. The first compensation layer is disposed parallel to the first thickened layer, and the first compensation layer and the first thickened layer together cover the first busbar. Therefore, even when the first thickened layer is deposited using photolithography and etching techniques, and a portion of the upper surface of the first busbar is exposed due to the shrinkage of the first thickened layer, the first compensation layer can still cover the exposed portion of the first busbar. This ensures that the first thickened layer and the first compensation layer together act as a mass load, completely covering the first busbar.

[0036] Similarly, this application also deposits a second compensation layer on the second busbar. The second compensation layer is disposed parallel to the second thickened layer, and the second compensation layer and the second thickened layer together cover the second busbar. Therefore, even when the second thickened layer is deposited using photolithography and etching techniques, and a portion of the upper surface of the second busbar is exposed due to the shrinkage of the second thickened layer, the second compensation layer can still cover the exposed portion of the second busbar. This ensures that the second thickened layer and the second compensation layer together act as a mass load to completely cover the second busbar.

[0037] Therefore, the above structure can compensate for the shrinkage of the first and second thickened layers caused by the manufacturing process, allowing the first and second busbars to be completely covered by the mass load. Consequently, the transverse modes in the surface acoustic wave resonator are effectively suppressed, improving the performance of the surface acoustic wave resonator. Furthermore, compared to existing transverse mode suppression technologies, the structure of this application is simpler, has a larger process window, and is less susceptible to process limitations; and it has less impact on the Q value of the surface acoustic wave resonator.

[0038] Optionally, the first busbar 210, the first thickened layer 211 and the first compensation layer 212 are made of aluminum, and the second busbar 220, the second thickened layer 221 and the second compensation layer 222 are also made of aluminum.

[0039] Optionally, the thickness of the first thickened layer 211 is greater than 0.7 μm, and the thickness of the second thickened layer 221 is greater than 0.7 μm. Further optionally, the thickness of the first compensation layer 212 is greater than 0.7 μm, and the thickness of the second compensation layer 222 is greater than 0.7 μm.

[0040] Specifically, refer to Figure 1 As shown, the first thickened layer 211 and the first compensation layer 212 have the same thickness and are both greater than 0.7 μm; the second thickened layer 221 and the second compensation layer 222 have the same thickness and are both greater than 0.7 μm.

[0041] As a result, the sound velocity at the first busbar 210 and the second busbar 220 decreases, and the transverse mode leakage occurs. At this time, the stray response on the admittance curve disappears, and the transverse mode of the surface acoustic wave resonator is effectively suppressed. Furthermore, the greater the thickness of the first thickened layer 211 and the first compensation layer 212, and the greater the thickness of the second thickened layer 221 and the second compensation layer 222, the better the transverse mode suppression effect.

[0042] Optionally, the material of the first busbar 210 may be different from the materials of the first thickened layer 211 and the first compensation layer 212; and the material of the second busbar 220 may be different from the materials of the second thickened layer 221 and the second compensation layer 222. It should be clear to those skilled in the art that, in this embodiment, the material of the first busbar 210 may be different from the materials of the first thickened layer 211 and the first compensation layer 212. Similarly, the material of the second busbar 220 may also be different from the materials of the second thickened layer 221 and the second compensation layer 222. Further details will not be elaborated here.

[0043] Optionally, the material of the first busbar 210 is the same as the material of the first thickened layer 211 and the first compensation layer 212; and the material of the second busbar 220 is the same as the material of the second thickened layer 221 and the second compensation layer 222. Furthermore, the materials of the first busbar 210, the first thickened layer 211, and the first compensation layer 212 are copper, and the materials of the second busbar 220, the second thickened layer 221, and the second compensation layer 222 are also copper.

[0044] Specifically, Figure 3 This is a comparison of sound velocity curves at different duty cycles for an interdigital transducer made of aluminum and an interdigital transducer made of copper, as described in this embodiment. (Reference) Figure 3 As shown, the propagation speed of surface acoustic waves (SAWs) in interdigital transducers made of aluminum and copper is lowest at a duty factor of approximately DF = 0.65. Furthermore, the propagation speed of SAWs in copper interdigital transducers is lower than that in aluminum interdigital transducers. Existing SAW resonators are typically designed for a duty cycle range of 0.4–0.6, within which the sound velocity at the interdigital electrode units is lower than that at the busbar. Therefore, when the transverse component of the SAW propagates to the busbar, reflection occurs, forming a standing wave and thus exciting the transverse mode.

[0045] To suppress transverse modes in the surface acoustic wave resonator, the busbars, thickening layers, and compensation layers in this application use different metallic materials.

[0046] Figure 4 These are comparative images showing the suppression of lateral modes when the busbar, thickened layer, and compensation layer, as described in the embodiments of this application, are made of gold, platinum, chromium, cobalt, and aluminum. (Reference) Figure 4 As shown, in surface acoustic wave (SAW) resonators, the busbars and their mass loads are typically made of aluminum, resulting in multiple stray responses (multiple small peaks) on the admittance curve. However, in the SAW resonator provided in this application, the first busbar 210, the first thickened layer 211, and the first compensation layer 212 are made of copper, as are the second busbar 220, the second thickened layer 221, and the second compensation layer 222. In this case, for the first busbar 210 and the second busbar 220, which already have mass loads, the mass load on the first busbar 210 and the second busbar 220 increases because copper has a higher density than aluminum and therefore a greater mass for the same thickness. Consequently, the sound velocity at the first busbar 210 and the second busbar 220 decreases, and transverse mode leakage occurs. It can be observed that the stray responses on the admittance curve disappear, and the transverse modes of the SAW resonator are effectively suppressed.

[0047] Optionally, the first busbar 210, the first thickened layer 211 and the first compensation layer 212 are made of platinum, and the second busbar 220, the second thickened layer 221 and the second compensation layer 222 are also made of platinum.

[0048] Specifically, refer to Figure 4 As shown, the first busbar 210, the first thickening layer 211, and the first compensation layer 212 are made of platinum, as are the second busbar 220, the second thickening layer 221, and the second compensation layer 222. In this case, for the first busbar 210 and the second busbar 220, which already have a mass load, the mass load on the first busbar 210 and the second busbar 220 increases because platinum has a higher density than aluminum and therefore a greater mass for the same thickness. Consequently, the sound velocity at the first busbar 210 and the second busbar 220 decreases, and transverse mode leakage occurs. At this point, the stray response portion on the admittance curve disappears, and the transverse mode of the surface acoustic wave resonator is partially suppressed.

[0049] Optionally, the first busbar 210, the first thickened layer 211, and the first compensation layer 212 are made of gold, and the second busbar 220, the second thickened layer 221, and the second compensation layer 222 are also made of gold.

[0050] Specifically, refer to Figure 4 As shown, the first busbar 210, the first thickened layer 211, and the first compensation layer 212 are made of gold, and the second busbar 220, the second thickened layer 221, and the second compensation layer 222 are also made of gold. In this case, for the first busbar 210 and the second busbar 220, which already have a mass load, the mass load on the first busbar 210 and the second busbar 220 increases because gold has a higher density than aluminum and therefore a greater mass for the same thickness. Consequently, the sound velocity at the first busbar 210 and the second busbar 220 decreases, and the transverse mode leakage occurs. At this point, the stray response portion on the admittance curve disappears, and the transverse mode of the surface acoustic wave resonator is partially suppressed.

[0051] Furthermore, when the materials of the first busbar 210, the first thickened layer 211, and the first compensation layer 212 are chromium, and the materials of the second busbar 220, the second thickened layer 221, and the second compensation layer 222 are also chromium, the stray response on the admittance curve increases, the transverse mode of the surface acoustic wave resonator is not suppressed, and even deterioration occurs.

[0052] Optionally, the interdigital transducer 200 further includes an interdigital electrode unit 230, wherein the interdigital electrode unit 230 includes a plurality of first electrode fingers 231 extending from the first busbar 210 and into the second busbar 220, a plurality of second electrode fingers 232 extending from the second busbar 220 and into the first busbar 210, a plurality of first dummy fingers 233 extending from the first busbar 210 and disposed opposite to the second electrode fingers 232 on the opposite side, and a plurality of second dummy fingers 234 extending from the second busbar 220 and disposed opposite to the first electrode fingers 231 on the opposite side.

[0053] Specifically, refer to Figure 1 As shown, the interdigitated electrode unit 230 includes a plurality of first electrode fingers 231, a plurality of second electrode fingers 232, a plurality of first pseudo-fingers 233, and a plurality of second pseudo-fingers 234. Specifically, a plurality of first electrode fingers 231 extending towards the second busbar 220 are provided at one end of the first busbar 210 facing the second busbar 220, and a plurality of second electrode fingers 232 extending towards the first busbar 210 are provided at one end of the second busbar 220 facing the first busbar 210. The first electrode fingers 231 and the second electrode fingers 232 are spaced apart and interleaved on the piezoelectric substrate 100. Furthermore, a plurality of first pseudo-fingers 233, opposite to the second electrode fingers 232, are provided at one end of the first busbar 210 facing the second busbar 220, and a plurality of second pseudo-fingers 234, opposite to the first electrode fingers 231, are provided at one end of the second busbar 220 facing the first busbar 210.

[0054] Optionally, a plurality of first electrode fingers 231 and a plurality of second electrode fingers 232 overlap each other to form an overlapping region 235, wherein the boundary shape of the overlapping region 235 conforms to a trigonometric function curve in the direction of sound wave propagation, wherein the trigonometric function curve includes a sine function curve and a cosine function curve; and the shapes of the first busbar 210 and the second busbar 220 match the boundary shape of the overlapping region 235.

[0055] Specifically, Figure 5 This is a schematic diagram of another surface acoustic wave resonator according to this application. (Reference) Figure 5 As shown, since multiple first electrode fingers 231 extend from the first busbar 210 and into the second busbar 220, and multiple second electrode fingers 232 extend from the second busbar 220 and into the first busbar 210, and since the multiple first electrode fingers 231 and multiple second electrode fingers 232 are spaced apart from each other, the multiple first electrode fingers 231 and multiple second electrode fingers 232 can overlap each other and form an overlapping region 235. The upper boundary of the overlapping region 235 corresponds to the end of the multiple consecutive first electrode fingers 231. The lower boundary of the overlapping region 235 corresponds to the end of the multiple consecutive second electrode fingers 232.

[0056] It is worth noting that the boundary shape of the overlapping region 235 formed in this application conforms to a trigonometric function curve. This trigonometric function curve includes both sine and cosine function curves. Specifically, the ends of multiple consecutive first electrode fingers 231 conform to a trigonometric function curve (corresponding to the upper boundary of the overlapping region 235), and the ends of multiple consecutive second electrode fingers 232 conform to a trigonometric function curve (corresponding to the lower boundary of the overlapping region 235). In other words, when fabricating the multiple first electrode fingers 231 and multiple second electrode fingers 232, this application non-uniformly designs the overlap length of the multiple first electrode fingers 231 and multiple second electrode fingers 232, ensuring that the apodized weighted average of the multiple first electrode fingers 231 and multiple second electrode fingers 232 conforms to a trigonometric function curve, thereby effectively suppressing transverse mode clutter.

[0057] In addition, refer to Figure 1 It can be seen that the existing first busbar 210 and second busbar 220 are arranged relatively parallel to each other, and there are non-overlapping portions between the first busbar 210 and the overlapping portion, and there are also non-overlapping portions between the second busbar 220 and the overlapping portion. And as described above... Figure 1 Unlike the surface acoustic wave (SAW) filter shown, this application provides another type of SAW filter. Furthermore, the shapes of the first busbar 210 and the second busbar 220 in this SAW filter match the boundary shape of the overlapping region 235, and there are no non-overlapping regions between the first busbar 210 and the overlapping region 235, nor between the second busbar 220 and the overlapping region 235. The overlapping region 235 corresponds to the effective region, and the non-overlapping region corresponds to the ineffective region.

[0058] In other words, by matching the shapes of the first busbar 210 and the second busbar 220 with the boundary shape of the overlapping region 235, this application can reduce ineffective regions. This effectively improves the efficiency of the surface acoustic wave filter and enables the implementation of small-sized surface acoustic wave filters.

[0059] Furthermore, it is worth noting that the type of surface acoustic wave filter in this application may include, but is not limited to, thin-film surface acoustic wave filter (TF-SAW) or temperature-compensated surface acoustic wave filter (TC-SAW), without limitation.

[0060] Optionally, the ratio between the minimum and maximum longitudinal overlap lengths of the plurality of first electrode fingers 231 and the plurality of second electrode fingers 232 is less than or equal to 40%.

[0061] Specifically, refer to Figure 5As shown, since the shape of the boundary (including the upper and lower boundaries) of the overlapping region 235 conforms to a trigonometric function curve in the direction of sound wave propagation, the longitudinal length of the overlapping region 235 is not fixed but continuously changing. Therefore, the longitudinal length of the overlapping region 235 has a maximum and a minimum value, meaning the longitudinal overlap length of the multiple first electrode fingers 231 and the multiple second electrode fingers 232 has a maximum and a minimum value.

[0062] In this embodiment, the ratio between the minimum and maximum longitudinal overlap lengths of the first electrode finger 231 and the second electrode finger 232 is less than or equal to 40%.

[0063] Therefore, by setting the ratio between the minimum and maximum longitudinal overlap lengths of the first electrode finger 231 and the second electrode finger 232 to less than or equal to 40%, the area utilization rate of the effective region of the surface acoustic wave filter can be improved while suppressing transverse mode clutter.

[0064] Optionally, the boundary length of the overlapping region 235 is greater than or equal to a trigonometric function curve with a period of 0.4.

[0065] Specifically, refer to Figure 5 As shown, the boundary shape of the overlapping region 235 conforms to a trigonometric function curve. Furthermore, in this embodiment, the boundary length of the overlapping region 235 (including the upper and lower boundary lengths) is greater than or equal to 0.4 periods of a trigonometric function curve. Therefore, based on this, the effective region utilization of the surface acoustic wave filter is maximized.

[0066] Optionally, it further includes: a first reflector 240 and a second reflector 250 respectively disposed on both sides of the interdigital transducer 200, wherein the first reflector 240 includes a third bus bar 241, a fourth bus bar 242 and a plurality of third electrode fingers 243 respectively connected to the third bus bar 241 and the fourth bus bar 242, and the second reflector 250 includes a fifth bus bar 251, a sixth bus bar 252 and a plurality of fourth electrode fingers 253 respectively connected to the fifth bus bar 251 and the sixth bus bar 252; in the direction of sound wave propagation, the third bus bar corresponding to the first reflector 240 is... The shape of busbar 241 continues the shape of the first busbar 210 and extends in the form of a trigonometric function curve; the shape of the fourth busbar 242 corresponding to the first reflector 240 continues the shape of the second busbar 220 and extends in the form of a trigonometric function curve; and in the direction of sound wave propagation, the shape of the fifth busbar 251 corresponding to the second reflector 250 continues the shape of the first busbar 210 and extends in the form of a trigonometric function curve; the shape of the sixth busbar 252 corresponding to the second reflector 250 continues the shape of the second busbar 220 and extends in the form of a trigonometric function curve.

[0067] Specifically, refer to Figure 5 As shown, the surface acoustic wave filter also includes a first reflector 240 and a second reflector 250 respectively disposed on both sides of the interdigital transducer 200. The first reflector 240 includes a third bus bar 241 and a fourth bus bar 242, and a plurality of third electrode fingers 243 are connected between the third bus bar 241 and the fourth bus bar 242. The second reflector 250 includes a fifth bus bar 251 and a sixth bus bar 252, and a plurality of fourth electrode fingers 253 are connected between the fifth bus bar 251 and the sixth bus bar 252.

[0068] Furthermore, in manufacturing the first reflector 240, the shape of the third busbar 241 corresponding to the first reflector 240 continues the shape of the first busbar 210 and extends in the form of a trigonometric function curve. The shape of the fourth busbar 242 corresponding to the first reflector 240 continues the shape of the second busbar 220 and extends in the form of a trigonometric function curve.

[0069] Therefore, when the shape of the busbars of the first reflector 240 (including the third busbar 241 and the fourth busbar 242) continues the shape of the busbars of the interdigital transducer 200 (including the first busbar 210 and the second busbar 220) and extends in the form of a trigonometric function curve, the continuity of the impedance characteristics of the surface acoustic wave during propagation can be ensured, and unnecessary sound wave scattering or energy loss can be avoided.

[0070] Similarly, in manufacturing the second reflector 250, the shape of the fifth busbar 251 corresponding to the second reflector 250 continues the shape of the first busbar 210 and extends in the form of a trigonometric function curve. The shape of the sixth busbar 252 corresponding to the second reflector 250 continues the shape of the second busbar 220 and extends in the form of a trigonometric function curve.

[0071] Therefore, when the shape of the busbars of the second reflector 250 (including the fifth busbar 251 and the sixth busbar 252) continues the shape of the busbars of the interdigital transducer 200 (including the first busbar 210 and the second busbar 220) and extends in the form of a trigonometric function curve, the continuity of the impedance characteristics of the surface acoustic wave during propagation can be ensured, and unnecessary sound wave scattering or energy loss can be avoided.

[0072] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0073] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0074] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms 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 on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0075] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A surface acoustic wave resonator, comprising: The piezoelectric substrate (100) and the interdigital transducer (200) disposed on the piezoelectric substrate (100) are characterized in that, The interdigitated transducer (200) includes: a first busbar (210) and a second busbar (220) arranged in parallel, a first thickened layer (211) disposed vertically above the first busbar (210) and a second thickened layer (221) disposed vertically above the second busbar (220), wherein... The first end (2111) of the first thickened layer (211) is aligned with the end of the first busbar (210) away from the second busbar (220), and the second end (2211) of the second thickened layer (221) is aligned with the end of the second busbar (220) away from the first busbar (210); The interdigitated transducer (200) further includes: a first compensation layer (212) disposed vertically above the first busbar (210) and a second compensation layer (222) disposed vertically above the second busbar (220), and The third end (2121) of the first compensation layer (212) is aligned with the end of the first busbar (210) near the end of the second busbar (220), and the fourth end (2221) of the second compensation layer (222) is aligned with the end of the second busbar (220) near the end of the first busbar (210).

2. A surface acoustic wave resonator according to claim 1, characterized in that, The thickness of the first thickened layer (211) is greater than 0.7 μm, and the thickness of the second thickened layer (221) is greater than 0.7 μm.

3. A surface acoustic wave resonator according to claim 2, characterized in that, The thickness of the first compensation layer (212) is greater than 0.7 μm, and the thickness of the second compensation layer (222) is greater than 0.7 μm.

4. A surface acoustic wave resonator according to claim 1, characterized in that, The material of the first busbar (210) is different from the materials of the first thickened layer (211) and the first compensation layer (212); and The material of the second busbar (220) is different from the materials of the second thickened layer (221) and the second compensation layer (222).

5. A surface acoustic wave resonator according to claim 1, characterized in that, The material of the first busbar (210) is the same as the material of the first thickened layer (211) and the first compensation layer (212); and The material of the second busbar (220) is the same as that of the second thickened layer (221) and the second compensation layer (222).

6. A surface acoustic wave resonator according to claim 5, characterized in that, The first busbar (210), the first thickened layer (211) and the first compensation layer (212) are made of aluminum, and the second busbar (220), the second thickened layer (221) and the second compensation layer (222) are also made of aluminum.

7. A surface acoustic wave resonator according to claim 5, characterized in that, The first busbar (210), the first thickened layer (211), and the first compensation layer (212) are made of copper, and the second busbar (220), the second thickened layer (221), and the second compensation layer (222) are also made of copper.

8. A surface acoustic wave resonator according to claim 5, characterized in that, The first busbar (210), the first thickened layer (211), and the first compensation layer (212) are made of platinum, and the second busbar (220), the second thickened layer (221), and the second compensation layer (222) are also made of platinum.

9. A surface acoustic wave resonator according to claim 5, characterized in that, The first busbar (210), the first thickened layer (211) and the first compensation layer (212) are made of gold, and the second busbar (220), the second thickened layer (221) and the second compensation layer (222) are also made of gold.

10. A surface acoustic wave resonator according to claim 1, characterized in that, The interdigital transducer (200) further includes interdigital electrode units (230), wherein The interdigitated electrode unit (230) includes a plurality of first electrode fingers (231) extending from the first busbar (210) and into the second busbar (220), a plurality of second electrode fingers (232) extending from the second busbar (220) and into the first busbar (210), a plurality of first dummy fingers (233) extending from the first busbar (210) and positioned opposite the second electrode fingers (232), and a plurality of second dummy fingers (234) extending from the second busbar (220) and positioned opposite the first electrode fingers (231).

11. A surface acoustic wave resonator according to claim 10, characterized in that, The plurality of first electrode fingers (231) and the plurality of second electrode fingers (232) overlap each other to form an overlapping region (235), wherein, in the direction of sound wave propagation, the boundary shape of the overlapping region (235) conforms to a trigonometric function curve, wherein the trigonometric function curve includes a sine function curve and a cosine function curve; and The shapes of the first busbar (210) and the second busbar (220) match the boundary shape of the overlapping region (235).

12. A surface acoustic wave resonator according to claim 11, characterized in that, The ratio between the minimum and maximum longitudinal overlap lengths of the plurality of first electrode fingers (231) and the plurality of second electrode fingers (232) is less than or equal to 40%.

13. A surface acoustic wave resonator according to claim 11, characterized in that, The boundary length of the overlapping region (235) is greater than or equal to a trigonometric function curve with 0.4 periods.

14. A surface acoustic wave resonator according to claim 11, characterized in that, Also includes: A first reflector (240) and a second reflector (250) are respectively disposed on both sides of the interdigital transducer (200), wherein The first reflector (240) includes a third bus bar (241), a fourth bus bar (242), and a plurality of third electrode fingers (243) respectively connected to the third bus bar (241) and the fourth bus bar (242). The second reflector (250) includes a fifth bus bar (251), a sixth bus bar (252), and a plurality of fourth electrode fingers (253) respectively connected to the fifth bus bar (251) and the sixth bus bar (252). In the direction of sound wave propagation, the shape of the third busbar (241) corresponding to the first reflector (240) continues the shape of the first busbar (210) and extends in the form of a trigonometric function curve, and the shape of the fourth busbar (242) corresponding to the first reflector (240) continues the shape of the second busbar (220) and extends in the form of a trigonometric function curve; as well as In the direction of sound wave propagation, the shape of the fifth busbar (251) corresponding to the second reflector (250) continues the shape of the first busbar (210) and extends in the form of a trigonometric function curve, and the shape of the sixth busbar (252) corresponding to the second reflector (250) continues the shape of the second busbar (220) and extends in the form of a trigonometric function curve.

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