Surface acoustic wave device, multiplexer and radio frequency front-end module

Abstract

The application discloses a surface acoustic wave device, a multiplexer and a radio frequency front-end module, and relates to the technical field of radio frequency filtering. The surface acoustic wave device comprises a piezoelectric substrate, a first interdigital transducer and a second interdigital transducer. The first interdigital transducer and the second interdigital transducer are electrically connected and arranged on the piezoelectric substrate. The first interdigital transducer and the second interdigital transducer each comprise two bus bars arranged oppositely, and a plurality of electrode fingers arranged at intervals between the two bus bars and alternately connected with the two bus bars. The material of the plurality of electrode fingers in the first interdigital transducer is the same. The plurality of electrode fingers in the second interdigital transducer comprises a plurality of first electrode fingers and a plurality of second electrode fingers. The material of the first electrode fingers is different from that of the second electrode fingers. M second electrode fingers are arranged every N first electrode fingers. The application can effectively weaken the resonance peak of the second interdigital transducer and effectively avoid the adverse effects of capacitive resonance on the passband.

Description

Technical Field

[0001] This application relates to the field of radio frequency filtering technology, and in particular to a surface acoustic wave device, a multiplexer, and a radio frequency front-end module. Background Technology

[0002] Surface acoustic wave (SAW) devices, such as SAW filters, are devices that convert electrical signals into acoustic signals or vice versa. They offer advantages such as small size, high stability, strong anti-interference capability, and high selectivity. SAW devices typically consist of a piezoelectric substrate and an interdigital transducer (IDT). The IDT can be used to convert electrical signals into acoustic signals or vice versa.

[0003] Currently, IDTs are also commonly used as capacitors, typically electrically coupled to resonators in an electrically cascaded manner to adjust the out-of-band rejection of surface acoustic wave (SAW) devices. Generally, capacitors using IDT structures, due to their periodic structure, are prone to resonance in their electrical admittance response, which can affect the passband of SAW filters. Related technologies aim to reduce the impact of capacitor resonance on the filter's passband by increasing the finger spacing of the capacitor components to shift the resonant point out of band. However, this increases the area of ​​the SAW device, making it difficult to meet practical application requirements. Summary of the Invention

[0004] This application provides a surface acoustic wave device, a multiplexer, and an RF front-end module that can effectively avoid the adverse effects of capacitor resonance on the passband without increasing the area.

[0005] In a first aspect, this application provides a surface acoustic wave device, the surface acoustic wave device comprising a piezoelectric substrate, a first interdigital transducer and a second interdigital transducer; The first interdigital transducer is electrically connected to the second interdigital transducer and is disposed on the piezoelectric substrate. The first interdigital transducer and the second interdigital transducer each include two busbars disposed opposite each other and a plurality of electrode fingers arranged at intervals between the two busbars and alternately connected to the two busbars. The multiple electrode fingers in the first interdigital transducer are made of the same material; The second interdigital transducer includes multiple first electrode fingers and multiple second electrode fingers. The materials of the first electrode fingers are different from those of the second electrode fingers. Furthermore, M second electrode fingers are provided every N first electrode fingers. Wherein, N≥1, M≥1, and N and M are positive integers.

[0006] Secondly, this application provides a surface acoustic wave device, which includes a piezoelectric substrate, a first interdigital transducer, and a capacitor. The multiple electrode fingers in the first interdigital transducer are made of the same material; The capacitor has multiple electrode fingers, including multiple first electrode fingers and multiple second electrode fingers. The materials of the first electrode fingers are different from those of the second electrode fingers. Furthermore, M second electrode fingers are provided every N first electrode fingers. Wherein, N≥1, M≥1, and N and M are positive integers.

[0007] Thirdly, this application provides a multiplexer, which includes the surface acoustic wave device as described above.

[0008] Fourthly, this application provides a radio frequency front-end module, which includes the multiplexer as described above.

[0009] This application provides a surface acoustic wave (SAW) device, a multiplexer, and a radio frequency (RF) front-end module. The SAW device includes at least a piezoelectric substrate, interdigital transducers, and a suppression structure. A first interdigital transducer and a second interdigital transducer are electrically connected and both are disposed on the piezoelectric substrate. Each of the first and second interdigital transducers includes two busbars arranged opposite each other and a plurality of electrode fingers arranged at intervals between the two busbars and alternately connected to the two busbars. The plurality of electrode fingers in the first interdigital transducer are made of the same material. The plurality of electrode fingers in the second interdigital transducer includes a plurality of first electrode fingers and a plurality of second electrode fingers. The materials of the first electrode fingers and the second electrode fingers are different. Furthermore, M second electrode fingers are disposed every N first electrode fingers, where N≥1, M≥1, and N and M are positive integers. By differentiating the materials of the first and second electrode fingers in the second interdigital transducer, the resonance peak of the second interdigital transducer can be weakened, effectively avoiding the adverse effects of capacitor resonance on the passband. At the same time, it can also ensure that the size of the surface acoustic wave device is small, thereby improving the performance and practicality of the surface acoustic wave device. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a top view schematic diagram of a surface acoustic wave device provided in an embodiment of this application; Figure 2 This is a cross-sectional structural schematic diagram of a surface acoustic wave device provided in an embodiment of this application; Figure 3 This is a cross-sectional view of a piezoelectric substrate provided in an embodiment of this application; Figure 4 This is a cross-sectional view of a second interdigital transducer provided in an embodiment of this application; Figure 5 This is a cross-sectional view of another second interdigital transducer provided in an embodiment of this application, wherein the ratio of the number of first electrode fingers to the number of second electrode fingers is 1:1 and N=M=2; Figure 6 This is a cross-sectional view of another second interdigital transducer provided in an embodiment of this application, wherein two first electrode fingers are provided between each pair of adjacent second electrode fingers; Figure 7 This is a cross-sectional view of another second interdigital transducer provided in an embodiment of this application, wherein three first electrode fingers are provided between every two adjacent second electrode fingers; Figure 8 This is a schematic diagram comparing the real part of the admittance curves of the second interdigital transducer provided in Example 1 of a surface acoustic wave device with those of the interdigital transducers provided in Comparative Examples 1 and 2. Figure 9 This is a schematic diagram comparing the real part of the admittance curves of the second interdigital transducer provided in Example 1 of another surface acoustic wave device with those of the interdigital transducers provided in Comparative Examples 1 and 2. Figure 10 This is a schematic diagram comparing the real part of the admittance of the second interdigital transducer provided in Embodiments 2, 3, 4, and 5 of a surface acoustic wave device with that of the interdigital transducer provided in Comparative Examples 1 and 2. Figure 11 This is a schematic diagram comparing the real part of the admittance curves of the second interdigital transducer provided in Embodiments 2, 3, 4, and 5 of another surface acoustic wave device with those of the interdigital transducer provided in Comparative Examples 1 and 2. Detailed Implementation

[0012] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0013] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0014] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0015] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0016] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0017] Please see Figure 1 and Figure 2 , Figure 1 This is a top view schematic diagram of a surface acoustic wave device provided in an embodiment of this application. Figure 2 This is a cross-sectional structural schematic diagram of a surface acoustic wave device provided in an embodiment of this application.

[0018] like Figure 1 and Figure 2 As shown, this application provides a surface acoustic wave device 100, which includes a piezoelectric substrate 10, a first interdigital transducer 20 and a second interdigital transducer 30, wherein the first interdigital transducer 20 and the second interdigital transducer 30 are disposed on the surface of the piezoelectric substrate 10.

[0019] In this embodiment, the first interdigital transducer 20 and the second interdigital transducer 30 are electrically connected. Optionally, the first interdigital transducer 20 and the second interdigital transducer 30 can be electrically connected through series connection or through parallel connection, without specific limitation. It should be noted that the first interdigital transducer 20 and the second interdigital transducer 30 can be considered electrically connected through either series or parallel connection.

[0020] For example, the material of the piezoelectric substrate 10 may include at least one of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3), without being specifically limited here. Choosing the above-mentioned material of the piezoelectric substrate 10 is beneficial to confining most of the energy of the surface acoustic wave within the piezoelectric substrate 10.

[0021] like Figure 3As shown, taking a piezoelectric substrate 10 as a POI (Piezoelectric on Insulator) substrate as an example, the piezoelectric substrate 10 may include a support layer 11, a functional layer 13 and a piezoelectric layer 14 stacked sequentially.

[0022] For example, the support layer 11 can be a high-resistivity silicon substrate (HR-Si). The support layer 11 can include materials such as silicon, silicon carbide, silicon nitride, and aluminum nitride, without specific limitations. The thickness of the support layer 11 is generally 300µm to 800µm, such as 300µm, 400µm, 500µm, 650µm, 800µm, etc.

[0023] For example, functional layer 13 may include a hypersonic layer and / or a temperature compensation layer. Taking a hypersonic layer as an example, the propagation speed of sound waves in the hypersonic layer is greater than that in the piezoelectric layer 14. The material of the hypersonic layer is different from that of the piezoelectric layer 14, thus utilizing the material difference to make the propagation speed of sound waves in the hypersonic layer greater than that in the piezoelectric layer 14. The material of the hypersonic layer can be silicon nitride, aluminum nitride, or aluminum oxide, etc. Taking a temperature compensation layer as an example, the temperature compensation layer plays a role in temperature compensation, thereby improving the negative frequency temperature characteristics of the piezoelectric layer 14. The material of the temperature compensation layer can be silicon oxide, tantalum oxide, silicon oxynitride, etc., which have a positive frequency temperature coefficient. Generally, the propagation speed of sound waves in the temperature compensation layer is slower than that in the piezoelectric layer 14. Therefore, the material of the functional layer 13 may include silicon dioxide, silicon oxynitride, tantalum oxide, silicon dioxide doped with fluorine, carbon, boron, hydrogen, and dielectric materials containing the above components, etc., without specific limitations. Its thickness is generally 200nm~1000nm, such as 200nm, 300nm, 500nm, 800nm, 1000nm, etc.

[0024] For example, the material of the piezoelectric layer 14 may include at least one of lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and aluminum nitride (AlN). The thickness of the piezoelectric layer 14 is generally 200nm~1000nm, such as 200nm, 400nm, 600nm, 750nm, 1000nm, etc., which is beneficial to confine most of the energy of the surface acoustic wave within the piezoelectric layer 14.

[0025] For example, a buffer layer 12 may also be provided between the support layer 11 and the functional layer 13. The material of the buffer layer 12 may be polycrystalline silicon. Polycrystalline silicon has good stability and conductivity and can effectively conduct charge under the action of an electric field, so that the buffer layer 12 can confine the sound wave energy, suppress parasitic spurious modes, and improve the quality factor and filtering performance of the filter.

[0026] The first interdigital transducer 20 and the second interdigital transducer 30 each include two busbars 40 arranged opposite to each other, and a plurality of electrode fingers 50 arranged at intervals between the two busbars 40 and alternately connected to the two busbars 40, the plurality of electrode fingers 50 being arranged along a first direction between the two busbars 40.

[0027] For example, the electrode fingers 50 in the first interdigital transducer 20 and the second interdigital transducer 30 are elongated strips in a top view. The extension direction of the long side of the electrode finger 50 is perpendicular to the extension direction of the busbar 40, and multiple electrode fingers 50 are parallel to each other, with a certain gap between adjacent electrode fingers 50. In this embodiment of the invention, the electrode finger 50 needs to contact a busbar 40 to achieve electrical connection. The duty cycle of the electrode finger 50 can be 0.25-0.75, for example, 0.25, 0.3, 0.4, 0.5, 0.6, 0.75, etc., where the duty cycle (metallization ratio) is the ratio of the width of a single electrode finger 50 to the pitch, and the pitch is the spacing between the centerlines (parallel to the extension direction of the electrode finger 50) of two adjacent electrode fingers 50 in a first direction. The arrangement direction of the electrode fingers 50 can be the first direction (i.e., Figure 1 (In the lateral direction), the extension direction of electrode 50 can be a second direction (i.e., Figure 1 (the vertical direction in the middle).

[0028] For example, the cross-section of the electrode finger 50 formed under the influence of process conditions may be trapezoidal, where the cross-section refers to the cross-section perpendicular to the piezoelectric substrate 10.

[0029] For example, the material of busbar 40 may include one or more of the following metals: aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, etc. There is no specific limitation here, and it can be determined according to the specific situation. However, the selected material needs to have good conductivity.

[0030] Specifically, the multiple electrode fingers 50 in the first interdigital transducer 20 are made of the same material.

[0031] For example, each electrode finger 50 in the first interdigital transducer 20 is made of the same material, and the material of the electrode finger 50 in the first interdigital transducer 20 may include one or more of the following metals: aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, titanium, etc. The material of the electrode finger 50 in the second interdigital transducer 30 may also include one or more of the following metals: aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, titanium, etc. There is no specific limitation here, and it can be determined according to the specific situation, but the selected material needs to have good conductivity.

[0032] In some optional embodiments, the electrode fingers 50 in the first interdigital transducer 20 are all made of aluminum. In other optional embodiments, the electrode fingers 50 in the first interdigital transducer 20 are all made of molybdenum. In still other optional embodiments, the electrode fingers 50 in the first interdigital transducer 20 are all made of molybdenum-copper alloy. No specific limitations are made here.

[0033] Specifically, the multiple electrode fingers 50 in the second interdigital transducer 30 include multiple first electrode fingers 51 and multiple second electrode fingers 52. The materials of the first electrode fingers 51 and the second electrode fingers 52 are different. Furthermore, M second electrode fingers 52 are provided every N first electrode fingers 51; where N≥1, M≥1, and N and M are positive integers.

[0034] When both the first electrode finger 51 and the second electrode finger 52 consist of only one layer of metal, if the metal material of the first electrode finger 51 is different from the metal material of the second electrode finger 52, it is considered that the material of the first electrode finger 51 is different from the material of the second electrode finger 52.

[0035] When the first electrode finger 51 includes one layer of metal and the second electrode finger 52 includes at least two layers of metal, if the metal material of the first electrode finger 51 is different from the metal material of any one layer of the second electrode finger 52, it can be considered that the material of the first electrode finger 51 is different from the material of the second electrode finger 52.

[0036] When both the first electrode finger 51 and the second electrode finger 52 comprise at least two layers of metal, if at least one layer of metal in the first electrode finger 51 is made of a different material than the corresponding layer of metal in the second electrode finger 52, then the materials of the first electrode finger 51 and the second electrode finger 52 are considered to be different. It should be noted that differences in material properties or material distribution between the first electrode finger 51 and the second electrode finger 52 also constitute grounds for considering the materials of the first electrode finger 51 and the second electrode finger 52 to be different.

[0037] For example, both the first electrode finger 51 and the second electrode finger 52 include two layers of metal. The bottom layer of the first electrode finger 51 is made of aluminum, and the top layer of the first electrode finger 51 is made of copper. The bottom layer of the second electrode finger 52 is made of aluminum, and the top layer of the second electrode finger 52 is made of molybdenum. In this case, the top layer metals of the first electrode finger 51 and the second electrode finger 52 are different, so it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0038] For example, both the first electrode finger 51 and the second electrode finger 52 include two layers of metal. The bottom layer of the first electrode finger 51 is aluminum, and the top layer of the first electrode finger 51 is copper. The bottom layer of the second electrode finger 52 is copper, and the top layer of the second electrode finger 52 is aluminum. In this case, although the materials of the first electrode finger 51 and the second electrode finger 52 are the same, the materials used for the bottom layer metal and the top layer metal are different. In the embodiments of this application, it is also considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0039] In other words, the materials of each layer of metal in the first electrode finger 51 and the second electrode finger 52 must be consistent for it to be considered that the material of the first electrode finger 51 is the same as the material of the second electrode finger 52.

[0040] For example, M second electrode fingers 52 are provided every N first electrode fingers 51, meaning that at least some of the first electrode fingers 51 and at least some of the second electrode fingers 52 are arranged alternately. Where N≥1, M≥1, and N and M are positive integers. Since the materials of the first electrode fingers 51 and the second electrode fingers 52 are different, by setting at least some of the first electrode fingers 51 and at least some of the second electrode fingers 52 alternately, the electrode fingers 50 in the second interdigital transducer 30 are material-differentiated. This causes the stress distribution and electrode mass density distribution in the second interdigital transducer 30 to be adjusted accordingly, thereby weakening the resonance peak of the second interdigital transducer 30, effectively avoiding the adverse effects of capacitive resonance on the passband, and thus improving the performance and practicality of the surface acoustic wave device 100. Moreover, this embodiment does not require increasing the finger spacing of the second interdigital transducer, nor does it require increasing the area of ​​the surface acoustic wave device, ensuring a small size of the surface acoustic wave device, thereby improving its performance and practicality.

[0041] For example, N and M can be any positive integer greater than or equal to 1, such as 1, 2, 3, 4, 5, etc., without specific limitations. For example, one second electrode finger 52 is provided every two first electrode fingers 51; another example, one second electrode finger 52 is provided every three first electrode fingers 51; another example, one second electrode finger 52 is provided every one first electrode finger 51; another example, two second electrode fingers 52 are provided every one first electrode finger 51; another example, two second electrode fingers 52 are provided every two first electrode fingers 51; without specific limitations.

[0042] The surface acoustic wave (SAW) device 100 provided in this application differentiates the materials of the first electrode finger 51 and the second electrode finger 52 in the second interdigital transducer 30. This adjusts the stress distribution and electrode mass density distribution in the second interdigital transducer 30 accordingly, thereby weakening the resonance peak of the second interdigital transducer 30, effectively avoiding the adverse effects of capacitive resonance on the passband, and ensuring a smaller size for the SAW device 100, thus improving its performance and practicality. It should be noted that, compared to a scheme where all electrode fingers 50 in the second interdigital transducer 30 are configured with the same material, the resonance peak of the second interdigital transducer 30 in this embodiment is significantly weakened, effectively avoiding the adverse effects of capacitive resonance on the passband when used as a capacitor, thereby improving the performance of the SAW device 100.

[0043] It should be noted that the surface acoustic wave device 100 provided in this application can be a temperature-compensated surface acoustic wave filter (TC-SAW), a multi-layer substrate type acoustic wave filter (POI-SAW), or other resonators or filters, without any specific limitations.

[0044] In some embodiments, the first electrode finger 51 and the second electrode finger 52 have different densities, and / or the first electrode finger 51 and the second electrode finger 52 have different elastic stiffness.

[0045] For example, the first electrode finger 51 and the second electrode finger 52 have different densities. Since the first electrode finger 51 and the second electrode finger 52 are made of different materials, their densities are generally also different. Taking the first electrode finger 51 as being made of aluminum and the second electrode finger 52 as being made of copper as an example, the density of the first electrode finger 51 is 2.70 g / cm³. 3 The density of the second electrode (52) is 8.96 g / cm³. 3By controlling the different densities of the first electrode finger 51 and the second electrode finger 52, the stress distribution and electrode mass density distribution in the second interdigital transducer 30 can be adjusted accordingly, thereby weakening the resonance peak of the second interdigital transducer 30 and effectively avoiding the adverse effects of capacitor resonance on the passband.

[0046] In some optional embodiments, the greater the density difference between the first electrode finger 51 and the second electrode finger 52, the more effectively the resonant peak of the second interdigital transducer 30 can be weakened, and the adverse effects of capacitor resonance on the passband can be suppressed. In other optional embodiments, the density ratio of the first electrode finger 51 to the second electrode finger 52 can be controlled within a preset range, such as 2 to 5, which can suppress the adverse effects of capacitor resonance on the passband while taking into account other electrical and physical properties of the second interdigital transducer 30.

[0047] For example, the first electrode finger 51 and the second electrode finger 52 have different elastic stiffnesses. Since the first electrode finger 51 and the second electrode finger 52 are made of different materials, their elastic stiffnesses are generally also different. Taking the first electrode finger 51 as being made of aluminum and the second electrode finger 52 as being made of copper as an example, the elastic stiffness (elastic modulus) of the first electrode finger 51 is 69-72 GPa, and the elastic stiffness (elastic modulus) of the second electrode finger 52 is 110-135 GPa. By controlling the difference in elastic stiffness between the first electrode finger 51 and the second electrode finger 52, the stress distribution and electrode mass density distribution in the second interdigital transducer 30 can be adjusted accordingly, thereby weakening the resonant peak of the second interdigital transducer 30 and effectively avoiding the adverse effects of capacitive resonance on the passband.

[0048] In some optional embodiments, the larger the difference in elastic stiffness between the first electrode finger 51 and the second electrode finger 52, the more effectively the resonant peak of the second interdigital transducer 30 can be weakened, and the adverse effects of capacitor resonance on the passband can be suppressed. In other optional embodiments, the difference in elastic stiffness between the first electrode finger 51 and the second electrode finger 52 can be controlled within a preset range, such as 30 GPa to 80 GPa, which can suppress the adverse effects of capacitor resonance on the passband while taking into account other electrical and physical properties of the second interdigital transducer 30.

[0049] In some embodiments, the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 is 6:1 to 1:1.

[0050] For example, the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 can be 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, etc., and is not specifically limited here. By controlling the number of first electrode fingers 51 to be greater than or equal to the number of second electrode fingers 52, and the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 to be 6:1-1:1, the adverse effects of capacitor resonance on the passband can be suppressed more effectively, and the resonance peak of the second interdigital transducer 30 can be further weakened.

[0051] In some embodiments, the number of first electrode fingers 51 and second electrode fingers 52 are the same, and N=M.

[0052] like Figure 4 As shown, exemplarily, when the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 is 1:1 and N=M=1, that is, it is equivalent to setting one second electrode finger 52 for every one first electrode finger 51. At this time, the first electrode fingers 51 and the second electrode fingers 52 are arranged alternately, that is, there is one first electrode finger 51 between every two adjacent second electrode fingers 52, and there is one second electrode finger 52 between every two adjacent first electrode fingers 51.

[0053] like Figure 5 As shown, for example, when the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 is 1:1 and N=M=2, that is, when every 2 first electrode fingers 51 are separated by 2 second electrode fingers 52, every 2 first electrode fingers 51 and every 2 second electrode fingers 52 are arranged alternately.

[0054] For example, when the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 is 1:1 and N=M=3, that is, every 3 first electrode fingers 51 are provided with 3 second electrode fingers 52, and at this time, every 3 first electrode fingers 51 and every 3 second electrode fingers 52 are arranged alternately.

[0055] It should be noted that N and M can be any positive integers and can be set according to the actual situation; no specific restrictions are made here.

[0056] like Figure 4 As shown, in some embodiments, the two busbars 40 in the second interdigital transducer 30 include a first busbar 40 and a second busbar 40, a plurality of first electrode fingers 51 are connected to the first busbar 40, a plurality of second electrode fingers 52 are connected to the second busbar 40, and the first electrode fingers 51 and the second electrode fingers 52 are alternately arranged in a first direction between the first busbar 40 and the second busbar 40.

[0057] For example, the two busbars 40 in the second interdigital transducer 30 include a first busbar 40 and a second busbar 40 arranged opposite to each other. The first busbar 40 is connected to a plurality of first electrode fingers 51, and the second busbar 40 is connected to a plurality of second electrode fingers 52. The plurality of first electrode fingers 51 and the plurality of second electrode fingers 52 are arranged alternately, so the first electrode fingers 51 and the second electrode fingers 52 are arranged adjacent to each other. Taking four electrode fingers 50 arranged consecutively in the second interdigital transducer 30 as an example, if the first electrode finger 50 is the first electrode finger 51, then the second electrode finger 50 is the second electrode finger 52, the third electrode finger 50 is the first electrode finger 51, and the fourth electrode finger 50 is the second electrode finger 52.

[0058] In this embodiment, the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 is 1:1 and N=M=1, which means that there is one second electrode finger 52 for every one first electrode finger 51. At this time, each first electrode finger 51 and each second electrode finger 52 are arranged alternately, and there is one first electrode finger 51 between every two adjacent second electrode fingers 52. By controlling the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 to be 1:1 and N=M=1, the materials of every two adjacent electrode fingers 50 in the second interdigital transducer 30 can be differentiated, thereby making the material differentiation of the electrode fingers 50 more prominent. This can more effectively suppress the adverse effects of capacitor resonance on the passband, and further weaken the resonance peak of the second interdigital transducer 30.

[0059] In some embodiments, N≥2 and N=M.

[0060] like Figure 5 As shown, for example, taking a ratio of 1:1 between the number of first electrode fingers 51 and the number of second electrode fingers 52 and N=M=2 as an example, this is equivalent to having two second electrode fingers 52 every two first electrode fingers 51. In this case, every two first electrode fingers 51 and every two second electrode fingers 52 are arranged alternately, and there are two first electrode fingers 51 between every two adjacent second electrode fingers 52. By controlling the ratio of the number of first electrode fingers 51 to the number of second electrode fingers 52 to be 1:1 and N=M=2, the two electrode fingers 50 spaced apart in the second interdigital transducer 30 can be material-differentiated, thereby making the material difference of the electrode fingers 50 more prominent, which can more effectively suppress the adverse effect of capacitor resonance on the passband, and further weaken the resonance peak of the second interdigital transducer 30.

[0061] In the above scenario, for any one first electrode finger 51, it is arranged adjacent to another first electrode finger 51 and a second electrode finger 52; for any one second electrode finger 52, it is arranged adjacent to another second electrode finger 52 and a first electrode finger 51. Two adjacent first electrode fingers 51 are connected to different busbars 40, and two adjacent second electrode fingers 52 are connected to different busbars 40. Taking four consecutive electrode fingers 50 in the second interdigital transducer 30 as an example (consecutive cycles), if the first electrode finger 50 is a first electrode finger 51, the second electrode finger 50 is a first electrode finger 51, then the third electrode finger 50 is a second electrode finger 52, and the fourth electrode finger 50 is a second electrode finger 52.

[0062] In some embodiments, the number of first electrode fingers 51 is greater than the number of second electrode fingers 52, and N first electrode fingers 51 are provided between every two adjacent second electrode fingers 52, where N≥2.

[0063] like Figure 6 As shown, for example, the number of first electrode fingers 51 is greater than the number of second electrode fingers 52. Two first electrode fingers 51 are provided between every two adjacent second electrode fingers 52, that is, two first electrode fingers 51 are provided between every two adjacent second electrode fingers 52. Taking the four electrode fingers 50 in the second interdigital transducer 30 as an example of one cycle, the first electrode finger 50 is a second electrode finger 52, the second electrode finger 50 is a first electrode finger 51, the third electrode finger 50 is a first electrode finger 51, and the fourth electrode finger 50 is a second electrode finger 52.

[0064] By controlling the number of first electrode fingers 51 to be greater than the number of second electrode fingers 52, and setting N first electrode fingers 51 between each two adjacent second electrode fingers 52, and N≥2, the material differentiation of the electrode fingers 50 can be made more prominent, thereby more effectively suppressing the adverse effects of capacitor resonance on the passband, and further weakening the resonance peak of the second interdigital transducer 30.

[0065] In some embodiments, three first electrode fingers 51 are provided between every two adjacent second electrode fingers 52.

[0066] like Figure 7 As shown, for example, the number of first electrode fingers 51 is greater than the number of second electrode fingers 52, and there are 3 first electrode fingers 51 between every two adjacent second electrode fingers 52. Taking the five electrode fingers 50 consecutively arranged in the second interdigital transducer 30 as an example, if the first electrode finger 50 is the second electrode finger 52, then the second electrode finger 50 is the first electrode finger 51, the third electrode finger 50 is the first electrode finger 51, the fourth electrode finger 50 is the first electrode finger 51, and the fifth electrode finger 50 is the second electrode finger 52.

[0067] In some embodiments, the first electrode finger 51 and the second electrode finger 52 each include two layers of metal stacked sequentially from bottom to top; wherein at least one layer of metal in the first electrode finger 51 is made of a different material than the corresponding layer of metal in the second electrode finger 52.

[0068] For example, when both the first electrode finger 51 and the second electrode finger 52 consist of two layers of metal stacked sequentially from bottom to top, if at least one layer of metal in the first electrode finger 51 is made of a different material than the corresponding layer of metal in the second electrode finger 52, it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different. By controlling that the materials of at least one layer of metal in the first electrode finger 51 are different from the corresponding layer of metal in the second electrode finger 52, the resonant peak of the second interdigital transducer 30 can be weakened, effectively avoiding the adverse effects of capacitive resonance on the passband.

[0069] For example, both the first electrode finger 51 and the second electrode finger 52 include two layers of metal stacked sequentially from bottom to top on the piezoelectric substrate 10. The metal disposed on the surface of the piezoelectric substrate 10 is the first layer of metal (i.e., the bottom layer of metal), and the metal disposed on the side of the first layer of metal away from the piezoelectric substrate 10 is the second layer of metal (i.e., the top layer of metal). The first layer of metal in the first electrode finger 51 and the first layer of metal in the second electrode finger 52 are corresponding layers, and the second layer of metal in the first electrode finger 51 and the second layer of metal in the second electrode finger 52 are also corresponding layers.

[0070] For example, the material of the first layer of metal of the first electrode finger 51 is aluminum, the material of the second layer of metal of the first electrode finger 51 is copper, the material of the first layer of metal of the second electrode finger 52 is aluminum, and the material of the second layer of metal of the second electrode finger 52 is molybdenum. In this case, the materials used for the second layer of metal of the first electrode finger 51 and the corresponding layer of the second electrode finger 52 are different, so it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0071] For example, the material of the first layer of metal of the first electrode finger 51 is aluminum, the material of the second layer of metal of the first electrode finger 51 is copper, the material of the first layer of metal of the second electrode finger 52 is copper, and the material of the second layer of metal of the second electrode finger 52 is aluminum. In this case, the materials used for the first layer of metal and the second layer of metal of the first electrode finger 51 are different from those used for the corresponding layers of the second electrode finger 52. Therefore, it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0072] It should be noted that if the materials of the first layer metal of the first electrode finger 51 and the first layer metal of the second electrode finger 52 are different, or if the materials of the second layer metal of the first electrode finger 51 and the second layer metal of the second electrode finger 52 are different, it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0073] In some embodiments, both the first electrode finger 51 and the second electrode finger 52 include a first metal layer and a second metal layer stacked sequentially from bottom to top; wherein the thickness of the second metal layer is greater than the thickness of the first metal layer, the material of the first metal layer in the second electrode finger 52 is the same as the material of the first metal layer in the first electrode finger 51, and the material of the second metal layer in the second electrode finger 52 is different from the material of the second metal layer in the first electrode finger 51; or, the thickness of the second metal layer is less than the thickness of the first metal layer, the material of the first metal layer in the second electrode finger 52 is different from the material of the first metal layer in the first electrode finger 51, and the material of the second metal layer in the second electrode finger 52 is the same as the material of the second metal layer in the first electrode finger 51.

[0074] For example, the thickness of the second metal layer is greater than that of the first metal layer. The material of the first metal layer in the second electrode finger 52 is copper, just as the material of the first metal layer in the first electrode finger 51 is copper. The material of the second metal layer in the second electrode finger 52 is aluminum, while the material of the second metal layer in the first electrode finger 51 is silver. That is, the material of the second metal layer in the second electrode finger 52 is different from that in the first electrode finger 51. By controlling the difference in the material of the thicker second metal layer in the first electrode finger 51 and the second electrode finger 52, the metal materials with a larger proportion in the first electrode finger 51 and the second electrode finger 52 can be different. This further weakens the resonance peak of the second interdigital transducer 30 and further suppresses the adverse effects of capacitive resonance on the passband.

[0075] For example, the thickness of the second metal layer is less than that of the first metal layer. The material of the second metal layer in the second electrode finger 52 is copper, just like the material of the first metal layer in the first electrode finger 51. However, the material of the first metal layer in the second electrode finger 52 is aluminum, while the material of the first metal layer in the first electrode finger 51 is silver. That is, the material of the first metal layer in the second electrode finger 52 is different from that in the first electrode finger 51. By controlling the material of the thicker first metal layer in the first electrode finger 51 and the second electrode finger 52 to be different, the metal materials with a larger proportion in the first electrode finger 51 and the second electrode finger 52 can be different. This can further suppress the adverse effect of capacitive resonance on the passband, and also further weaken the resonance peak of the second interdigital transducer 30.

[0076] In some embodiments, the first electrode finger 51 and the second electrode finger 52 each include three layers of metal stacked sequentially from bottom to top; wherein at least one layer of metal in the first electrode finger 51 is made of a different material than the corresponding layer of metal in the second electrode finger 52.

[0077] In this embodiment, both the first electrode finger 51 and the second electrode finger 52 comprise three layers of metal stacked sequentially from bottom to top. The metal disposed on the surface of the piezoelectric substrate 10 in the first electrode finger 51 is the first layer of metal (i.e., the bottom layer metal), the metal disposed on the surface of the first layer of metal in the first electrode finger 51 is the second layer of metal (i.e., the middle layer metal), and the metal disposed on the surface of the second layer of metal in the first electrode finger 51 is the third layer of metal (i.e., the top layer metal). The first layer of metal in the first electrode finger 51 corresponds to the first layer of metal in the second electrode finger 52, the second layer of metal in the first electrode finger 51 corresponds to the second layer of metal in the second electrode finger 52, and the third layer of metal in the first electrode finger 51 corresponds to the third layer of metal in the second electrode finger 52.

[0078] For example, the material of the first layer of metal of the first electrode finger 51 is copper, the material of the second layer of metal of the first electrode finger 51 is aluminum, the material of the third layer of metal of the first electrode finger 51 is aluminum, the material of the first layer of metal of the second electrode finger 52 is molybdenum, the material of the second layer of metal of the second electrode finger 52 is aluminum, and the material of the third layer of metal of the second electrode finger 52 is aluminum. In this case, the materials used for the first layer of metal of the first electrode finger 51 and the corresponding layer of the second electrode finger 52 are different, so it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0079] For example, the first layer of metal of the first electrode finger 51 is made of aluminum, the second layer of metal of the first electrode finger 51 is made of copper, the third layer of metal of the first electrode finger 51 is made of silver, the first layer of metal of the second electrode finger 52 is made of copper, the second layer of metal of the second electrode finger 52 is made of aluminum, and the third layer of metal of the first electrode finger 51 is made of silver. In this case, the materials used for the first and second layers of metal of the first electrode finger 51 are different from those used for the corresponding layers of the second electrode finger 52. Therefore, it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0080] It should be noted that if the materials of the first layer metal of the first electrode finger 51 and the first layer metal of the second electrode finger 52 are different, or if the materials of the second layer metal of the first electrode finger 51 and the second layer metal of the second electrode finger 52 are different, or if the materials of the second layer metal of the first electrode finger 51 and the second layer metal of the second electrode finger 52 are different, it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0081] In some embodiments, the first electrode finger 51 and the second electrode finger 52 each include a first metal layer, a second metal layer, and a third metal layer stacked sequentially from bottom to top; wherein, the material of the first metal layer in the second electrode finger 52 is the same as the material of the first metal layer in the first electrode finger 51, the material of the third metal layer in the second electrode finger 52 is the same as the material of the third metal layer in the first electrode finger 51, and the material of the second metal layer in the second electrode finger 52 is different from the material of the second metal layer in the first electrode finger 51.

[0082] For example, the first layer of metal on the first electrode finger 51 is made of aluminum, the second layer of metal on the first electrode finger 51 is made of copper, and the third layer of metal on the first electrode finger 51 is made of aluminum. Similarly, the first layer of metal on the second electrode finger 52 is made of aluminum, the second layer of metal on the second electrode finger 52 is made of molybdenum, and the third layer of metal on the second electrode finger 52 is made of aluminum. In this case, the materials used for the corresponding layers of the first electrode finger 51 and the second electrode finger 52 are different, which means that the materials of the first electrode finger 51 and the second electrode finger 52 are considered different. By controlling the materials of the intermediate layer metals to be different, while the materials of the top and bottom layer metals are the same, it is possible to weaken the resonance peak of the second interdigital transducer 30, suppress the adverse effects of capacitor resonance on the passband, simplify the fabrication process of the second interdigital transducer, and reduce manufacturing costs.

[0083] In some embodiments, the distance between two adjacent electrode fingers 50 in the second interdigital transducer 30 in the first direction is less than the distance between two adjacent electrode fingers 50 in the first interdigital transducer 20 in the first direction, where the first direction is the arrangement direction of the electrode fingers 50.

[0084] For example, since the second interdigital transducer 30 includes a first electrode finger 51 and a second electrode finger 52 made of different materials, the difference in materials between the first electrode finger 51 and the second electrode finger 52 may cause a frequency shift in the entire second interdigital transducer. As one implementation, the resonant frequency of the second interdigital transducer 30 shifts to a lower frequency. This embodiment of the application also adjusts the distance between two adjacent electrode fingers 50 in the second interdigital transducer 30 in the first direction to effectively avoid the frequency shift caused by the different materials of the first electrode finger 51 and the second electrode finger 52.

[0085] Specifically, the distance between two adjacent electrode fingers 50 in the second interdigital transducer 30 in the first direction is negatively correlated with the resonant frequency of the surface acoustic wave device 100. That is, the greater the distance between two adjacent electrode fingers 50 in the first direction in the second interdigital transducer 30, the smaller the resonant frequency of the surface acoustic wave device 100; the smaller the distance between two adjacent electrode fingers 50 in the first direction in the second interdigital transducer 30, the greater the resonant frequency of the surface acoustic wave device 100.

[0086] In one implementation, the different materials of the first electrode finger 51 and the second electrode finger 52 cause the frequency of the second interdigital transducer 30 to shift to a lower frequency. Therefore, the distance between two adjacent electrode fingers 50 in the first direction in the second interdigital transducer 30 is reduced to compensate for (increase) the frequency. Thus, the distance between two adjacent electrode fingers 50 in the first direction in the second interdigital transducer 30 is smaller than the distance between two adjacent electrode fingers 50 in the first interdigital transducer 20 in the first direction.

[0087] It should be noted that if the different materials of the first electrode finger 51 and the second electrode finger 52 cause the frequency of the second interdigital transducer 30 to shift to a higher frequency, the distance between two adjacent electrode fingers 50 in the first direction in the second interdigital transducer 30 can be increased. That is, the distance between two adjacent electrode fingers 50 in the first direction in the second interdigital transducer 30 is greater than the distance between two adjacent electrode fingers 50 in the first interdigital transducer 20 in the first direction, so as to effectively avoid the frequency shift caused by the different materials of the first electrode finger 51 and the second electrode finger 52.

[0088] In some embodiments, the surface acoustic wave device 100 further includes a temperature compensation layer 60, which at least covers the first interdigital transducer 20. The temperature compensation layer 60 may be made of a material with a positive frequency temperature coefficient, such as silicon oxide, tantalum oxide, or silicon oxynitride, thereby compensating for the temperature drift of the surface acoustic wave device 100 caused by the negative frequency temperature characteristics of the piezoelectric substrate 10.

[0089] For example, the temperature compensation layer 60 covers at least the first interdigital transducer 20, thereby ensuring the overall frequency and temperature stability of the surface acoustic wave device 100.

[0090] Optionally, the temperature compensation layer 60 may or may not cover the second interdigital transducer 30.

[0091] In some embodiments, the temperature compensation layer 60 does not cover the second interdigital transducer 30; or, the temperature compensation layer 60 also covers the second interdigital transducer 30, and the thickness of the temperature compensation layer 60 covering the second interdigital transducer 30 is less than the thickness covering the first interdigital transducer 20.

[0092] Specifically, the resonant frequency of the surface acoustic wave device 100 is negatively correlated with the thickness of the temperature compensation layer 60. That is, the greater the thickness of the temperature compensation layer 60 covering the second interdigital transducer 30, the smaller the resonant frequency of the surface acoustic wave device 100; the smaller the thickness of the temperature compensation layer 60 covering the second interdigital transducer 30, the greater the resonant frequency of the surface acoustic wave device 100.

[0093] For example, since the second interdigital transducer 30 includes a first electrode finger 51 and a second electrode finger 52 made of different materials, the frequency of the second interdigital transducer 30 shifts to a lower frequency. Therefore, the thickness of the temperature compensation layer 60 covering the second interdigital transducer 30 is reduced to compensate for the frequency reduction. Thus, the thickness of the temperature compensation layer 60 covering the second interdigital transducer 30 is less than the thickness covering the first interdigital transducer 20.

[0094] It should be noted that if the different materials of the first electrode finger 51 and the second electrode finger 52 cause the frequency to shift to a higher frequency, the thickness of the temperature compensation layer 60 covering the second interdigital transducer 30 can be increased, that is, the thickness of the temperature compensation layer 60 on the second interdigital transducer 30 can be made greater than the thickness of the temperature compensation layer 60 on the first interdigital transducer 20, so as to avoid the frequency shift of the surface acoustic wave device caused by the different materials of the first electrode finger 51 and the second electrode finger 52.

[0095] In some embodiments, the material of the first electrode finger 51 includes a conductive material, and the material of the second electrode finger 52 includes a conductive material containing heavy metal elements.

[0096] For example, the material of the first electrode 51 includes a conductive material, and the material of the second electrode 52 includes a conductive material containing heavy metal elements. For example, the conductive material can be a material with good conductivity. For instance, the conductive material can include one or more of the following metals: aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, and titanium. No specific limitation is made here, and the choice can be made according to the specific circumstances. Heavy metal elements generally refer to elements with a density greater than 4.5 g / cm³. 3 The metallic elements, including heavy metal elements, may include one or more combinations of copper, magnesium, nickel, neodymium and scandium, aluminum and manganese, without specific limitations.

[0097] The material of the first electrode finger 51 is different from that of the second electrode finger 52. For example, the first electrode finger 51 may not contain heavy metal elements, or if the first electrode finger 51 is a multilayer structure, at least one layer of the first electrode finger 51 may not contain heavy metal elements. For example, at least one layer of the first electrode finger 51 may be made of Al without heavy metal elements.

[0098] In some optional embodiments, the first electrode finger 51 may be made of aluminum, and the second electrode finger 52 may be made of aluminum containing copper. In other optional embodiments, the first electrode finger 51 may be made of copper, and the second electrode finger 52 may be made of copper containing aluminum. In still other optional embodiments, the first electrode finger 51 may be made of aluminum, and the second electrode finger 52 may be made of copper containing nickel. No specific limitations are imposed here.

[0099] It should be noted that, in the embodiments of this application, if the elements doped in the first electrode finger 51 and the second electrode finger 52 are different, it is also considered that the material of the first electrode finger 51 is different from the material of the second electrode finger 52.

[0100] In other embodiments, if the first electrode finger 51 and the second electrode finger 52 are made of different main materials, the material of the second electrode finger 52 is further configured to include a conductive material containing heavy metal elements, thereby further increasing the material difference between the first electrode finger 51 and the second electrode finger 52, thereby further suppressing the adverse effect of capacitor resonance on the passband, and further weakening the resonance peak of the second interdigital transducer 30.

[0101] For example, if the first electrode finger 51 is primarily made of aluminum and the second electrode finger 52 is primarily made of copper, the material of the second electrode finger 52 can be further configured to include copper containing manganese. In this case, the material difference between the first electrode finger 51 and the second electrode finger 52 is further increased, thereby further suppressing the adverse effects of capacitive resonance on the passband, and further weakening the resonance peak of the second interdigital transducer 30.

[0102] In some embodiments, when the material of the second electrode finger 52 is aluminum, the heavy metal element includes at least one of copper, magnesium, nickel, neodymium, and scandium; when the material of the second electrode finger 52 is copper, the heavy metal element includes at least one of aluminum, manganese, and magnesium.

[0103] For example, when the material of the second electrode finger 52 is aluminum, the second electrode finger 52 can be aluminum containing copper, aluminum containing magnesium, aluminum containing nickel, aluminum containing neodymium, aluminum containing scandium, etc.

[0104] For example, when the material of the second electrode finger 52 is copper, the second electrode finger 52 can be copper containing aluminum, copper containing manganese, copper containing magnesium, etc.

[0105] In some embodiments, the material of the first electrode finger 51 is the same as the material of the electrode finger 50 in the first interdigital transducer 20, and the material of the second electrode finger 52 is different from the material of the electrode finger 50 in the first interdigital transducer 20.

[0106] For example, the material of the first electrode finger 51 can be the same as the material of the electrode finger 50 in the first interdigital transducer 20. For example, the material of the first electrode finger 51 and the material of the electrode finger 50 in the first interdigital transducer 20 can both be copper. However, the material of the second electrode finger 52 can be different from the material of the electrode finger 50 in the first interdigital transducer 20. For example, the material of the second electrode finger 52 can be aluminum, molybdenum, or other materials.

[0107] The following will provide a detailed description of another surface acoustic wave device 100 provided in the embodiments of this application.

[0108] like Figure 1 and Figure 2 As shown, this application provides a surface acoustic wave device 100, which includes a piezoelectric substrate 10, a first interdigital transducer 20 and a capacitor, wherein the first interdigital transducer 20 and the capacitor are disposed on the surface of the piezoelectric substrate 10.

[0109] In this embodiment, the first interdigital transducer 20 is electrically connected to the capacitor. Optionally, the first interdigital transducer 20 and the capacitor can be electrically connected through series connection or through parallel connection; no specific limitation is made here. It should be noted that either series or parallel connection between the first interdigital transducer 20 and the capacitor can be considered as an electrical connection.

[0110] For example, the material of the piezoelectric substrate 10 may include at least one of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3), without being specifically limited here. Choosing the above-mentioned material of the piezoelectric substrate 10 is beneficial to confining most of the energy of the surface acoustic wave within the piezoelectric substrate 10.

[0111] Both the first interdigital transducer 20 and the capacitor include two busbars 40 disposed opposite to each other, and a plurality of electrode fingers 50 arranged at intervals between the two busbars 40 and alternately connected to the two busbars 40, the plurality of electrode fingers 50 being arranged along a first direction between the two busbars 40.

[0112] It is not difficult to see that the capacitor in this embodiment is an interdigital capacitor, and its structure is the same as that of a conventional interdigital transducer, consisting of two busbars and electrode fingers alternately connected to the two busbars. Using an interdigital capacitor structure simplifies the fabrication process of the surface acoustic wave device 100.

[0113] For example, the electrode fingers 50 in the first interdigital transducer 20 and the capacitor are elongated strips in a top view. The extension direction of the long side of the electrode finger 50 is perpendicular to the extension direction of the busbar 40, and multiple electrode fingers 50 are parallel to each other, with a certain gap between adjacent electrode fingers 50. In this embodiment of the invention, the electrode finger 50 needs to be in contact with a busbar 40 to achieve electrical connection. The duty cycle of the electrode finger 50 can be 0.25-0.75, for example, 0.25, 0.3, 0.4, 0.5, 0.6, 0.75, etc., where the duty cycle (metallization ratio) is the ratio of the width of a single electrode finger 50 to the pitch, and the pitch is the spacing between the center lines (parallel to the extension direction of the electrode finger 50) of two adjacent electrode fingers 50 in a first direction. The arrangement direction of the electrode fingers 50 can be the first direction (i.e., Figure 1 (In the lateral direction), the extension direction of electrode 50 can be a second direction (i.e., Figure 1 (the vertical direction in the middle).

[0114] For example, the cross-section of the electrode finger 50 formed under the influence of process conditions may be trapezoidal, where the cross-section refers to the cross-section perpendicular to the piezoelectric substrate 10.

[0115] For example, the material of the busbar 40 may include one or more of the following metals: aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, etc. No specific limitation is made here; the material can be selected based on the specific circumstances. However, the selected material must have good electrical conductivity. It should be noted that the aforementioned specific materials (such as aluminum) are generally more prone to corrosion in alkaline environments.

[0116] Specifically, the multiple electrode fingers 50 in the first interdigital transducer 20 are made of the same material.

[0117] For example, each electrode finger 50 in the first interdigital transducer 20 is made of the same material, and the material of the electrode finger 50 in the first interdigital transducer 20 may include one or more of the following metals: aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, titanium, etc. The material of the electrode finger 50 in the capacitor may also include one or more of the following metals: aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, titanium, etc. There is no specific limitation here, and it can be determined according to the specific situation, but the selected material needs to have good conductivity.

[0118] In some optional embodiments, the electrode fingers 50 in the first interdigital transducer 20 are all made of aluminum. In other optional embodiments, the electrode fingers 50 in the first interdigital transducer 20 are all made of molybdenum. In still other optional embodiments, the electrode fingers 50 in the first interdigital transducer 20 are all made of molybdenum-copper alloy. No specific limitations are made here.

[0119] Specifically, the capacitor has multiple electrode fingers 50, including multiple first electrode fingers 51 and multiple second electrode fingers 52. The materials of the first electrode fingers 51 and the second electrode fingers 52 are different. Furthermore, M second electrode fingers 52 are provided every N first electrode fingers 51; where N≥1, M≥1, and N and M are positive integers.

[0120] When both the first electrode finger 51 and the second electrode finger 52 include a layer of metal, if the metal material of the first electrode finger 51 is different from the metal material of the second electrode finger 52, it can be considered that the material of the first electrode finger 51 is different from the material of the second electrode finger 52.

[0121] When the first electrode finger 51 includes one layer of metal and the second electrode finger 52 includes at least two layers of metal, if the metal material of the first electrode finger 51 is different from the metal material of any one layer of the second electrode finger 52, it can be considered that the material of the first electrode finger 51 is different from the material of the second electrode finger 52.

[0122] When both the first electrode finger 51 and the second electrode finger 52 comprise at least two layers of metal, if at least one layer of metal in the first electrode finger 51 is made of a different material than the corresponding layer of metal in the second electrode finger 52, then the materials of the first electrode finger 51 and the second electrode finger 52 are considered to be different. It should be noted that differences in material properties or material distribution between the first electrode finger 51 and the second electrode finger 52 also constitute grounds for considering the materials of the first electrode finger 51 and the second electrode finger 52 to be different.

[0123] For example, both the first electrode finger 51 and the second electrode finger 52 include two layers of metal. The bottom layer of the first electrode finger 51 is made of aluminum, and the top layer of the first electrode finger 51 is made of copper. The bottom layer of the second electrode finger 52 is made of aluminum, and the top layer of the second electrode finger 52 is made of molybdenum. In this case, the top layer metals of the first electrode finger 51 and the second electrode finger 52 are different, so it can be considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0124] For example, both the first electrode finger 51 and the second electrode finger 52 include two layers of metal. The bottom layer of the first electrode finger 51 is aluminum, and the top layer of the first electrode finger 51 is copper. The bottom layer of the second electrode finger 52 is copper, and the top layer of the second electrode finger 52 is aluminum. In this case, although the materials of the first electrode finger 51 and the second electrode finger 52 are the same, the materials used for the bottom layer metal and the top layer metal are different. In the embodiments of this application, it is also considered that the materials of the first electrode finger 51 and the second electrode finger 52 are different.

[0125] In other words, the materials of each layer of metal in the first electrode finger 51 and the second electrode finger 52 must be consistent for it to be considered that the material of the first electrode finger 51 is the same as the material of the second electrode finger 52.

[0126] For example, M second electrode fingers 52 are provided every N first electrode fingers 51, meaning that at least some of the first electrode fingers 51 and at least some of the second electrode fingers 52 are arranged alternately. Where N≥1, M≥1, and N and M are positive integers. Since the materials of the first electrode fingers 51 and the second electrode fingers 52 are different, by setting at least some of the first electrode fingers 51 and at least some of the second electrode fingers 52 alternately, material differentiation is achieved for the electrode fingers 50 in the capacitor. This causes the stress distribution and electrode mass density distribution in the second interdigital transducer 30 to be adjusted accordingly, thereby weakening the resonance peak of the second interdigital transducer 30, effectively avoiding the adverse effects of capacitor resonance on the passband, and thus improving the performance and practicality of the surface acoustic wave device 100.

[0127] For example, N and M can be any positive integer greater than or equal to 1, such as 1, 2, 3, 4, 5, etc., without specific limitations. For example, one second electrode finger 52 is provided every two first electrode fingers 51; another example, one second electrode finger 52 is provided every three first electrode fingers 51; another example, one second electrode finger 52 is provided every one first electrode finger 51; another example, two second electrode fingers 52 are provided every one first electrode finger 51; another example, two second electrode fingers 52 are provided every two first electrode fingers 51; without specific limitations.

[0128] The surface acoustic wave (SAW) device 100 provided in this application differentiates the materials of the first electrode fingers 51 and the second electrode fingers 52 in the capacitor, thereby adjusting the stress distribution and electrode mass density distribution in the capacitor accordingly. This weakens the resonance peak of the second interdigital transducer 30, effectively avoiding the adverse effects of capacitor resonance on the passband, and ensuring a smaller size for the SAW device 100, thus improving its performance and practicality. It should be noted that compared to a scheme where all electrode fingers 50 in the capacitor are configured with the same material, the resonance peak in this embodiment is significantly weakened, and its resonant frequency amplitude is reduced by nearly 50%.

[0129] It should be noted that in the embodiments of this application, the implementation method and function of the capacitor are the same as those of the second interdigital transducer 30. Therefore, the relevant embodiments of the capacitor can refer to the relevant embodiments of the second interdigital transducer 30 in the above embodiments, and the relevant embodiments of the first interdigital transducer 20 can refer to the above embodiments, which will not be repeated here.

[0130] In some embodiments, the first electrode finger 51 and the second electrode finger 52 have different densities, and / or the first electrode finger 51 and the second electrode finger 52 have different elastic stiffness.

[0131] For example, the first electrode finger 51 and the second electrode finger 52 have different densities. Since the first electrode finger 51 and the second electrode finger 52 are made of different materials, their densities are generally also different. Taking the first electrode finger 51 as being made of aluminum and the second electrode finger 52 as being made of copper as an example, the density of the first electrode finger 51 is 2.70 g / cm³. 3 The density of the second electrode (52) is 8.96 g / cm³. 3 By controlling the different densities of the first electrode finger 51 and the second electrode finger 52, the stress distribution and electrode mass density distribution in the capacitor can be adjusted accordingly, thereby weakening the resonance peak of the second interdigital transducer 30 and effectively avoiding the adverse effects of capacitor resonance on the passband.

[0132] In some optional embodiments, controlling the density difference between the first electrode finger 51 and the second electrode finger 52 to be greater can more effectively suppress the adverse effects of capacitor resonance on the passband, and can also further weaken the resonance peak of the second interdigital transducer 30; in other optional embodiments, controlling the density ratio of the first electrode finger 51 and the second electrode finger 52 within a preset range, such as a preset range of 2 to 5, can more effectively suppress the adverse effects of capacitor resonance on the passband, and can also further weaken the resonance peak of the second interdigital transducer 30.

[0133] For example, the elastic stiffness of the first electrode finger 51 and the second electrode finger 52 are different. Since the materials of the first electrode finger 51 and the second electrode finger 52 are different, their elastic stiffness is generally also different. Taking the material of the first electrode finger 51 as aluminum and the material of the second electrode finger 52 as copper, the elastic stiffness (elastic modulus) of the first electrode finger 51 is 69-72 GPa, and the elastic stiffness (elastic modulus) of the second electrode finger 52 is 110-135 GPa. By controlling the difference in elastic stiffness between the first electrode finger 51 and the second electrode finger 52, the stress distribution and electrode mass density distribution in the capacitor can be adjusted accordingly, thereby weakening the resonance peak of the second interdigital transducer 30 and effectively avoiding the adverse effects of capacitor resonance on the passband.

[0134] In some optional embodiments, a larger difference in elastic stiffness between the first electrode finger 51 and the second electrode finger 52 can more effectively suppress the adverse effects of capacitor resonance on the passband, and can also further weaken the resonance peak of the second interdigital transducer 30. In other optional embodiments, controlling the difference in elastic stiffness between the first electrode finger 51 and the second electrode finger 52 within a preset range, such as 30GPa to 80GPa, can more effectively suppress the adverse effects of capacitor resonance on the passband, and can also further weaken the resonance peak of the second interdigital transducer 30.

[0135] In one implementation, the ratio of the number of first electrode fingers to the number of second electrode fingers is 6:1 to 1:1.

[0136] In one implementation, the number of first electrode fingers is the same as the number of second electrode fingers, and N=M.

[0137] In one implementation, the capacitor has two busbars, including a first busbar and a second busbar. A plurality of first electrode fingers are connected to the first busbar, and a plurality of second electrode fingers are connected to the second busbar. The first electrode fingers and the second electrode fingers are alternately arranged between the first busbar and the second busbar along a first direction.

[0138] In one implementation, N≥2 and N=M.

[0139] In one implementation, the number of first electrode fingers is greater than the number of second electrode fingers, and N first electrode fingers are provided between every two adjacent second electrode fingers, where N≥2.

[0140] In one implementation, three first electrode fingers are provided between every two adjacent second electrode fingers.

[0141] In one embodiment, both the first electrode finger and the second electrode finger include two layers of metal stacked sequentially from bottom to top; wherein at least one layer of metal in the first electrode finger is made of a different material than the corresponding layer of metal in the second electrode finger.

[0142] In one embodiment, both the first electrode finger and the second electrode finger include a first metal layer and a second metal layer stacked sequentially from bottom to top; wherein, the thickness of the second metal layer is greater than the thickness of the first metal layer, the material of the first metal layer in the second electrode finger is the same as the material of the first metal layer in the first electrode finger, and the material of the second metal layer in the second electrode finger is different from the material of the second metal layer in the first electrode finger; or, the thickness of the second metal layer is less than the thickness of the first metal layer, the material of the first metal layer in the second electrode finger is different from the material of the first metal layer in the first electrode finger, and the material of the second metal layer in the second electrode finger is the same as the material of the second metal layer in the first electrode finger.

[0143] In one embodiment, both the first electrode finger and the second electrode finger include three layers of metal stacked sequentially from bottom to top; wherein at least one layer of metal in the first electrode finger is made of a different material than the corresponding layer of metal in the second electrode finger.

[0144] In one embodiment, both the first electrode finger and the second electrode finger include a first layer of metal, a second layer of metal, and a third layer of metal stacked sequentially from bottom to top; wherein, the material of the first layer of metal in the second electrode finger is the same as the material of the first layer of metal in the first electrode finger, the material of the third layer of metal in the second electrode finger is the same as the material of the third layer of metal in the first electrode finger, and the material of the second layer of metal in the second electrode finger is different from the material of the second layer of metal in the first electrode finger.

[0145] In one implementation, the distance between two adjacent electrode fingers in the capacitor in a first direction is less than the distance between two adjacent electrode fingers in the first interdigital transducer in a first direction, where the first direction is the arrangement direction of the electrode fingers.

[0146] As one implementation, the surface acoustic wave device further includes a temperature compensation layer, which at least covers the first interdigital transducer.

[0147] In one implementation, the temperature compensation layer does not cover the capacitor; or, the temperature compensation layer does cover the capacitor, and the thickness of the temperature compensation layer covering the capacitor is less than the thickness covering the first interdigital transducer.

[0148] In one embodiment, the material of the first electrode includes a conductive material, and the material of the second electrode includes a conductive material containing heavy metal elements.

[0149] In one embodiment, when the material of the second electrode is aluminum, the heavy metal element includes at least one of copper, magnesium, nickel, neodymium, and scandium; when the material of the second electrode is copper, the heavy metal element includes at least one of aluminum, manganese, and magnesium.

[0150] In one implementation, the electrode material includes at least one of aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, and titanium.

[0151] In one embodiment, the piezoelectric substrate is made of at least one of lithium niobate and lithium tantalate.

[0152] In one implementation, the first interdigital transducer is connected in series or in parallel with a capacitor.

[0153] In one implementation, the material of the first electrode finger is the same as the material of the electrode finger in the first interdigital transducer, and the material of the second electrode finger is different from the material of the electrode finger in the first interdigital transducer.

[0154] The following simulation experiments will compare the real part and amplitude variation curves of the admittance of the surface acoustic wave device (Example 1) provided in this application with those of the surface acoustic wave devices (Comparative Example 1 and Comparative Example 2) provided in related technologies. Figure 8 This is a schematic diagram comparing the admittance curves of the second interdigital transducer provided in Example 1 with those of the interdigital transducers provided in Comparative Examples 1 and 2 in a surface acoustic wave device (normal surface acoustic wave filter).

[0155] Figure 9 This is a schematic diagram comparing the admittance curves of the second interdigital transducer provided in Example 1 with those of Comparative Examples 1 and 2 in another type of surface acoustic wave device (temperature compensated surface acoustic wave filter, TC-SAW).

[0156] In the second interdigital transducer provided in Example 1, the first electrode finger is made of aluminum and the second electrode finger is made of copper. The ratio of the number of the first electrode finger to the number of the second electrode finger is 1:1, and the first electrode finger and the second electrode finger are arranged alternately, i.e., N=M=1. In Comparative Example 1, all electrode fingers of the interdigital transducer are made of aluminum. In Comparative Example 2, all electrode fingers of the interdigital transducer are made of copper.

[0157] like Figure 8 and Figure 9 As shown in the simulation experiment, the admittance curves of the two devices show that, compared with the surface acoustic wave (SAW) devices provided in Comparative Examples 1 and 2, the SAW device provided in Example 1 has a lower resonance peak, which is reduced by nearly 50% compared with Comparative Examples 1 and 2. This indicates that the resonance peak of the second interdigital transducer is significantly weakened. Therefore, it can be seen that the SAW device provided in this embodiment can effectively weaken the resonance peak of the second interdigital transducer, thereby reducing the impact on the passband of the SAW device and improving its performance and practicality.

[0158] The following simulation experiments will compare the real part and amplitude variation curves of the admittance of the second interdigital transducer in the surface acoustic wave devices (Examples 2, 3, 4, and 5) provided in this application with those of the interdigital transducers (Comparative Example 1 and Comparative Example 2) provided in related technologies. Figure 10 This is a schematic diagram comparing the admittance curves of the second interdigital transducers provided in Examples 2, 3, 4, and 5 of a surface acoustic wave device (normal surface acoustic wave filter, Normal-SAW) with those of the interdigital transducers provided in Comparative Examples 1 and 2. Figure 11 This is a schematic diagram comparing the admittance curves of the second interdigital transducers provided in Examples 2, 3, 4, and 5 of another surface acoustic wave device (temperature compensated surface acoustic wave filter, TC-SAW) with those of the interdigital transducers provided in Comparative Examples 1 and 2.

[0159] In Example 2, taking the four electrode fingers of the second interdigital transducer as one electrode finger cycle, the materials of the four electrode fingers of the second interdigital transducer in the surface acoustic wave device are aluminum, copper, aluminum, and aluminum, respectively, that is, one second electrode finger (made of copper) is provided every three first electrode fingers (made of aluminum); in Example 3, the materials of the four electrode fingers of the second interdigital transducer in the surface acoustic wave device are copper, aluminum, copper, and aluminum, respectively, that is, one second electrode finger (made of copper) is provided every one first electrode finger (made of aluminum); in Example 4, the materials of the second interdigital transducer in the surface acoustic wave device are copper, aluminum, copper, and aluminum, respectively, that is, one second electrode finger (made of copper) is provided every one first electrode finger (made of aluminum); The four electrode fingers of the device are made of copper, aluminum, copper, and copper in sequence, that is, three second electrode fingers (made of copper) are provided every other first electrode finger (made of aluminum); in Example 5, the four electrode fingers of the second interdigital transducer in the surface acoustic wave device are made of copper, copper, aluminum, and aluminum in sequence, that is, two second electrode fingers (made of copper) are provided every other two first electrode fingers (made of aluminum); in Comparative Example 1, all electrode fingers of the second interdigital transducer in the surface acoustic wave device are made of aluminum; in Comparative Example 2, all electrode fingers of the second interdigital transducer in the surface acoustic wave device are made of copper.

[0160] like Figure 10 and Figure 11 As shown in the simulation experiments, the admittance curve comparison charts reveal that, compared to the surface acoustic wave (SAW) devices provided in Comparative Examples 1 and 2, the amplitudes of the resonance peaks of the second interdigital transducers provided in Examples 2, 3, 4, and 5 are all lower than those of the ordinary interdigital transducers in Comparative Examples 1 and 2. This indicates that using first and second electrode fingers made of different materials in the capacitor / second interdigital transducer can effectively weaken the resonance peak of the capacitor / second interdigital transducer. Therefore, it can be seen that the SAW devices provided in this application can effectively avoid the adverse effects of capacitor resonance on the passband, and can also effectively weaken the resonance peaks of the SAW devices, thereby improving the performance and practicality of the SAW devices.

[0161] This application also provides a filter, which includes the surface acoustic wave device 100 described in any of the above embodiments.

[0162] When the filter includes a surface acoustic wave device 100, the filter provided in the embodiments of this application will be described in detail below.

[0163] The filter includes multiple series-arm surface acoustic wave (SAW) devices 100 connected in series between the input and output terminals, and multiple parallel-arm SAW devices 100 connected at one end to the series-arm SAW device 100 and at the other end to the ground terminal. At least one of the series-arm and parallel-arm SAW devices 100 can be the SAW device 100 provided in any of the above embodiments. This filter can reduce the resonance peak of the second interdigital transducer 30, effectively avoid the adverse effects of capacitor resonance on the passband, and thus improve the performance and practicality of the filter.

[0164] This application also provides a multiplexer that includes the filter described in any of the above embodiments. This multiplexer can reduce the resonance peak of the second interdigital transducer 30, effectively avoiding the adverse effects of capacitor resonance on the passband, thereby improving the performance and practicality of the multiplexer.

[0165] This application also provides an RF front-end module, which includes the filter or multiplexer described in any of the above embodiments. This RF front-end module can reduce the resonance peak of the second interdigital transducer 30, effectively avoiding the adverse effects of capacitor resonance on the passband, thereby improving the reliability, security, and practicality of the RF front-end module.

[0166] The surface acoustic wave device 100 can be integrated into a filter, duplexer, or multiplexer. The RF front-end module may also include at least one other device such as an antenna, power amplifier, low-noise amplifier, or switch, without specific limitations.

[0167] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered 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 device, characterized in that, The surface acoustic wave device includes: piezoelectric substrate; A first interdigital transducer and a second interdigital transducer are electrically connected and both are disposed on the piezoelectric substrate. Each of the first interdigital transducers and the second interdigital transducer includes two busbars disposed opposite to each other and a plurality of electrode fingers arranged at intervals between the two busbars and alternately connected to the two busbars. The multiple electrode fingers in the first interdigital transducer are made of the same material; The second interdigital transducer includes multiple first electrode fingers and multiple second electrode fingers. The materials of the first electrode fingers are different from those of the second electrode fingers. Furthermore, M second electrode fingers are provided every N first electrode fingers. Wherein, N≥1, M≥1, and N and M are positive integers.

2. The surface acoustic wave device according to claim 1, characterized in that, The first electrode finger and the second electrode finger have different densities, and / or the first electrode finger and the second electrode finger have different elastic stiffness.

3. The surface acoustic wave device according to claim 1, characterized in that, The ratio of the number of the first electrode fingers to the number of the second electrode fingers is 6:1 to 1:

1.

4. The surface acoustic wave device according to claim 3, characterized in that, The number of the first electrode fingers is the same as the number of the second electrode fingers, and N=M.

5. The surface acoustic wave device according to claim 4, characterized in that, The second interdigital transducer includes two busbars, namely a first busbar and a second busbar. The plurality of first electrode fingers are connected to the first busbar, and the plurality of second electrode fingers are connected to the second busbar. The first electrode fingers and the second electrode fingers are alternately arranged in a first direction between the first busbar and the second busbar.

6. The surface acoustic wave device according to claim 5, characterized in that, N≥2 and N=M.

7. The surface acoustic wave device according to claim 3, characterized in that, The number of the first electrode fingers is greater than the number of the second electrode fingers, and there are N first electrode fingers between every two adjacent second electrode fingers, where N≥2.

8. The surface acoustic wave device according to claim 7, characterized in that, There are 3 first electrode fingers between every two adjacent second electrode fingers.

9. The surface acoustic wave device according to claim 1, characterized in that, The first electrode finger and the second electrode finger each consist of two layers of metal stacked sequentially from bottom to top; In this embodiment, at least one layer of metal in the first electrode finger is made of a different material than the corresponding layer of metal in the second electrode finger.

10. The surface acoustic wave device according to claim 9, characterized in that, The first electrode finger and the second electrode finger each include a first metal layer and a second metal layer stacked sequentially from bottom to top; Wherein, the thickness of the second metal layer is greater than the thickness of the first metal layer, the material of the first metal layer in the second electrode finger is the same as the material of the first metal layer in the first electrode finger, and the material of the second metal layer in the second electrode finger is different from the material of the second metal layer in the first electrode finger; or... The thickness of the second metal layer is less than the thickness of the first metal layer. The material of the first metal layer in the second electrode finger is different from the material of the first metal layer in the first electrode finger, and the material of the second metal layer in the second electrode finger is the same as the material of the second metal layer in the first electrode finger.

11. The surface acoustic wave device according to claim 1, characterized in that, The first electrode finger and the second electrode finger each consist of three layers of metal stacked sequentially from bottom to top; In this embodiment, at least one layer of metal in the first electrode finger is made of a different material than the corresponding layer of metal in the second electrode finger.

12. The surface acoustic wave device according to claim 11, characterized in that, The first electrode finger and the second electrode finger each include a first metal layer, a second metal layer and a third metal layer stacked sequentially from bottom to top; The material of the first layer of metal in the second electrode finger is the same as that of the first layer of metal in the first electrode finger, the material of the third layer of metal in the second electrode finger is the same as that of the third layer of metal in the first electrode finger, and the material of the second layer of metal in the second electrode finger is different from that of the second layer of metal in the first electrode finger.

13. The surface acoustic wave device according to claim 1, characterized in that, The distance between two adjacent electrode fingers in the second interdigital transducer in the first direction is less than the distance between two adjacent electrode fingers in the first interdigital transducer in the first direction, where the first direction is the arrangement direction of the electrode fingers.

14. The surface acoustic wave device according to claim 1, characterized in that, The surface acoustic wave device further includes: A temperature compensation layer, which at least covers the first interdigital transducer.

15. The surface acoustic wave device according to claim 14, characterized in that, The temperature compensation layer does not cover the second interdigital transducer; or... The temperature compensation layer also covers the second interdigital transducer, and the thickness of the temperature compensation layer covering the second interdigital transducer is less than the thickness covering the first interdigital transducer.

16. The surface acoustic wave device according to claim 1, characterized in that, The first electrode refers to a material that is conductive, and the second electrode refers to a material that is conductive and contains heavy metal elements.

17. The surface acoustic wave device according to claim 16, characterized in that, When the material of the second electrode is aluminum, the heavy metal element includes at least one of copper, magnesium, nickel, neodymium, and scandium. When the material of the second electrode is copper, the heavy metal element includes at least one of aluminum, manganese and magnesium.

18. The surface acoustic wave device according to any one of claims 1-17, characterized in that, The electrode material includes at least one of aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, and titanium.

19. The surface acoustic wave device according to any one of claims 1-17, characterized in that, The material of the piezoelectric substrate includes at least one of lithium niobate and lithium tantalate.

20. The surface acoustic wave device according to any one of claims 1-17, characterized in that, The first interdigital transducer and the second interdigital transducer are connected in series or in parallel.

21. The surface acoustic wave device according to any one of claims 1-17, characterized in that, The material of the first electrode finger is the same as that of the electrode fingers in the first interdigital transducer, and the material of the second electrode finger is different from that of the electrode fingers in the first interdigital transducer.

22. A surface acoustic wave device, characterized in that, The surface acoustic wave device includes: piezoelectric substrate; A first interdigital transducer and a capacitor, wherein the first interdigital transducer is electrically connected to the capacitor and both are disposed on the piezoelectric substrate, and both the first interdigital transducer and the capacitor include two busbars disposed opposite to each other, and a plurality of electrode fingers arranged at intervals between the two busbars and alternately connected to the two busbars; The multiple electrode fingers in the first interdigital transducer are made of the same material; The capacitor has multiple electrode fingers, including multiple first electrode fingers and multiple second electrode fingers. The materials of the first electrode fingers are different from those of the second electrode fingers. Furthermore, M second electrode fingers are provided every N first electrode fingers. Wherein, N≥1, M≥1, and N and M are positive integers.

23. The surface acoustic wave device according to claim 22, characterized in that, The first electrode finger and the second electrode finger have different densities, and / or the first electrode finger and the second electrode finger have different elastic stiffness.

24. A multiplexer, characterized in that, Includes the surface acoustic wave device as described in any one of claims 1-23.

25. A radio frequency front-end module, characterized in that, Includes the multiplexer as described in claim 24.

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