Surface acoustic wave filter and multiplexer surface acoustic wave filter

Abstract

The invention discloses a surface acoustic wave filter and a multiplexer surface acoustic wave filter, and the surface acoustic wave filter comprises a first piezoelectric substrate and a first interdigital transducer which is arranged on the first piezoelectric substrate. The first interdigital transducer comprises a first bus bar, a second bus bar, a plurality of first electrode fingers and a plurality of second electrode fingers, the first bus bar and the second bus bar are oppositely arranged, the first electrode fingers are led out from the first bus bar and extend towards the second bus bar, the second electrode fingers are led out from the second bus bar and extend towards the first bus bar, and the first electrode fingers and the second electrode fingers are arranged at intervals; the plurality of first electrode fingers and the plurality of second electrode fingers are mutually overlapped to form a first overlapping area, and the boundary shape of the first overlapping area conforms to a trigonometric function curve in the sound wave propagation direction; and the shapes of the first bus bar and the second bus bar are matched with the boundary shape of the first overlapping region. The technical effects that the transverse mode can be inhibited, and the small-size surface acoustic wave filter can be realized are achieved.

Description

TECHNICAL FIELD

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

[0002] A surface acoustic wave filter (SAW) is an electronic device that uses the propagation characteristics of surface acoustic waves to achieve frequency selection, and is mainly used to excite a main surface acoustic wave. However, since the lengths of all the finger strips of the electrode fingers of most current surface acoustic wave filters are the same, the surface acoustic wave filter may excite an undesired transverse mode spurious wave in addition to the main surface acoustic wave, so that the transverse mode spurious wave generated by the surface acoustic wave filter will affect its passband performance.

[0003] In order to solve the above problem, a method of apodization is usually used to suppress the transverse mode spurious wave of the surface acoustic wave filter. Apodization refers to optimizing the frequency response of the surface acoustic wave filter by designing the overlapping lengths of the electrode fingers to be non-uniform. The core purpose is to suppress the transverse mode spurious wave by amplitude weighting in the spatial domain.

[0004] Figure 1 is a schematic diagram of a surface acoustic wave filter using the method of apodization to suppress the transverse mode spurious wave. As shown in Figure 1 , the surface acoustic wave filter includes a piezoelectric substrate 110 and an interdigital transducer 120 disposed on the piezoelectric substrate 110. The interdigital transducer 120 includes a first bus bar 121 and a second bus bar 122 arranged opposite to each other, and a plurality of first electrode fingers 123 extending from the first bus bar 121 to the second bus bar 122, and a plurality of second electrode fingers 124 extending from the second bus bar 122 to the first bus bar 121. Each first electrode finger 123 and each second electrode finger 124 are arranged opposite to each other, and the overlapping lengths of each first electrode finger 123 and each second electrode finger 124 are different.

[0005] Further, although the surface acoustic wave filter shown in Figure 1 uses the method of apodization to effectively suppress the transverse mode spurious wave, since the effective area of the capacitance (i.e. the parasitic capacitance formed between the piezoelectric substrate and the interdigital transducer) is determined by the overlapping parts of each first electrode finger 123 and each second electrode finger 124, and the non-overlapping parts are non-effective areas, the formation of the non-overlapping parts in the above Figure 1 easily causes material waste. Thus, it is not conducive to improving the use efficiency of the surface acoustic wave filter and the realization of a small-size surface acoustic wave filter.

[0006] A resonator and a surface acoustic wave filter are disclosed in CN120834788A. The resonator includes an interdigital transducer and a horizontal bar structure. The interdigital transducer includes a first bus bar, a second bus bar, a plurality of first finger strips, and a plurality of second finger strips. The first bus bar and the second bus bar are oppositely arranged. The same end of the plurality of first finger strips is connected to the side of the first bus bar close to the second bus bar. The same end of the plurality of second finger strips is connected to the side of the second bus bar close to the first bus bar. The horizontal bar structure is arranged in a target area of the interdigital transducer. The horizontal bar structure includes a plurality of first horizontal bars and a plurality of second horizontal bars. The plurality of first horizontal bars and the plurality of second horizontal bars are cross arranged. Adjacent first horizontal bars and second horizontal bars are distributed in a staggered manner. The first end of the first horizontal bar in the first direction is connected to the third end of the second horizontal bar in the first direction.

[0007] A surface acoustic wave resonator, a surface acoustic wave filter, and a duplexer are disclosed in CN117997301A. The surface acoustic wave resonator includes a substrate, a piezoelectric film arranged on the substrate, and an interdigital transducer formed on the piezoelectric film. The surface acoustic wave resonator further includes an electric field applying device for applying an electric field to the crystal of the piezoelectric film to form a ferroelectric domain wall capable of strongly reflecting a piezoelectric acoustic wave at the aperture boundary of the interdigital transducer. The ferroelectric domain wall makes the phase of the forward traveling wave toward the aperture boundary equal to the phase of the backward traveling wave toward the aperture boundary.

[0008] The prior art has the technical problem that although the surface acoustic wave filter manufactured by the current apodization method can effectively suppress the transverse mode spur, the area of the non-effective region is large, which is not conducive to improving the use efficiency of the surface acoustic wave filter and realizing a small size surface acoustic wave filter. No effective solution has been proposed so far. SUMMARY

[0009] The present disclosure provides a surface acoustic wave filter and a duplexer surface acoustic wave filter to at least solve the technical problem in the prior art that although the surface acoustic wave filter manufactured by the current apodization method can effectively suppress the transverse mode spur, the area of the non-effective region is large, which is not conducive to improving the use efficiency of the surface acoustic wave filter and realizing a small size surface acoustic wave filter.

[0010] According to an aspect of the present application, a surface acoustic wave filter is provided, comprising: a first piezoelectric substrate and a first interdigital transducer disposed on the first piezoelectric substrate, the first interdigital transducer comprising: a first bus bar and a second bus bar oppositely disposed, a plurality of first electrode fingers extending from the first bus bar to the second bus bar, and a plurality of second electrode fingers extending from the second bus bar to the first bus bar, and the plurality of first electrode fingers and the plurality of second electrode fingers are spaced apart from each other; the plurality of first electrode fingers and the plurality of second electrode fingers overlap with each other and form a first overlapping area, wherein in a direction of propagation of acoustic waves, a boundary shape of the first overlapping area conforms to a trigonometric function curve; and a shape of the first bus bar and the second bus bar matches the boundary shape of the first overlapping area.

[0011] According to another aspect of the present application, a multiplexer surface acoustic wave filter is provided, comprising: a first surface acoustic wave filter and a second surface acoustic wave filter sharing a same first bus bar with the first surface acoustic wave filter, wherein the first surface acoustic wave filter comprises a surface acoustic wave filter, and the second surface acoustic wave filter comprises: a second piezoelectric substrate and a second interdigital transducer disposed on the second piezoelectric substrate, wherein the second interdigital transducer comprises: the first bus bar and a seventh bus bar oppositely disposed, a plurality of fifth electrode fingers extending from the first bus bar to the seventh bus bar, and a plurality of sixth electrode fingers extending from the seventh bus bar to the first bus bar, and the plurality of fifth electrode fingers and the plurality of sixth electrode fingers are spaced apart from each other; the plurality of fifth electrode fingers and the plurality of sixth electrode fingers overlap with each other and form a second overlapping area, wherein in a direction of propagation of acoustic waves, a boundary shape of the second overlapping area conforms to a trigonometric function curve, and a concave-convex part of the first overlapping area and the second overlapping area engage with each other; and a shape of the first bus bar and the seventh bus bar matches the boundary shape of the second overlapping area.

[0012] The present application provides a surface acoustic wave filter and a multiplexer surface acoustic wave filter. And in the surface acoustic wave filter of the present application, the plurality of first electrode fingers and the plurality of second electrode fingers overlap with each other and form a first overlapping area with a boundary shape conforming to a trigonometric function curve. As described above, the boundary shape of the first overlapping area conforms to a trigonometric function curve, which means that the overlapping lengths of the plurality of first electrode fingers and the plurality of second electrode fingers used to form the first overlapping area are different. Therefore, by designing the overlapping lengths of the plurality of first electrode fingers and the plurality of second electrode fingers non-uniformly, the transverse mode spurs of the surface acoustic wave filter can be effectively suppressed.

[0013] In addition, since the shapes of the first bus bar and the second bus bar match the boundary shape of the first overlap region, there is no non-effective region between the first bus bar and the first overlap region and between the second bus bar and the first overlap region. That is, the effective region capable of being used as a capacitor exists between the first bus bar and the second bus bar of the surface acoustic wave filter. Therefore, the use efficiency of the surface acoustic wave filter can be effectively improved, and a small-size surface acoustic wave filter can be implemented.

[0014] Furthermore, the technical problem that although the surface acoustic wave filter manufactured by using the apodization method can effectively suppress the transverse mode spur, the area of the non-effective region is large, and thus the use efficiency of the surface acoustic wave filter cannot be improved and a small-size surface acoustic wave filter cannot be implemented is solved.

[0015] The above and other objects, advantages and features of the present application will become more apparent from the following detailed description of some embodiments thereof, when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0016] Some specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in different drawings denote the same or similar components or parts. It should be understood by those skilled in the art that the drawings are not necessarily drawn to scale. In the drawings: Figure 1 A schematic diagram of a prior art surface acoustic wave filter using an apodization method to suppress a transverse mode spur; Figure 2 A schematic diagram of a surface acoustic wave filter according to an embodiment of the present application; Figure 3 A structural schematic diagram of an electrode finger of a surface acoustic wave filter according to an embodiment of the present application; Figure 4 A power comparison diagram of a surface acoustic wave filter according to an embodiment of the present application and a prior art surface acoustic wave filter; Figure 5 A structural schematic diagram corresponding to a conductive layer being a copper layer according to an embodiment of the present application; Figure 6 A structural schematic diagram of an electrode finger with a conductive layer being a silver layer located between two adjacent second adhesive layers according to an embodiment of the present application; Figure 7 A power comparison diagram of a surface acoustic wave filter with a conductive layer being a silver layer and a surface acoustic wave filter with a conductive layer being a copper layer according to an embodiment of the present application; Figure 8 A structural schematic diagram of an electrode finger with a conductive layer being a platinum layer located between two adjacent second adhesive layers according to an embodiment of the present application; Figure 9 is a structural schematic diagram of a structure corresponding to the conductive layer being a copper-aluminum alloy layer according to an embodiment of the present application; Figure 10 is a power comparison diagram of a surface acoustic wave filter with the conductive layer being a copper-aluminum alloy layer and a surface acoustic wave filter with the conductive layer being a copper layer according to an embodiment of the present application; Figure 11 is a structural schematic diagram of an electrode finger with the conductive layer being a titanium-copper alloy layer according to an embodiment of the present application; Figure 12 is a structural schematic diagram of an electrode finger with the conductive layer being a molybdenum layer according to an embodiment of the present application; Figure 13 is a structural schematic diagram of an electrode finger with the first adhesive layer and the second adhesive layer being chromium layers according to an embodiment of the present application; Figure 14 is a structural schematic diagram of an electrode finger with the conductive layer between the second adhesive layer and the auxiliary conductive layer removed according to an embodiment of the present application; Figure 15 is a structural schematic diagram of a surface acoustic wave filter with the conductive layer removed in the middle and a surface acoustic wave filter without the conductive layer removed according to an embodiment of the present application; Figure 14 is a power comparison diagram of a surface acoustic wave filter with the conductive layer removed in the middle and a surface acoustic wave filter without the conductive layer removed according to an embodiment of the present application; Figure 16 is a structural schematic diagram of an electrode finger with the first adhesive layer being a titanium layer according to an embodiment of the present application; Figure 17 is a structural schematic diagram of an electrode finger with the auxiliary conductive layer being a silver layer according to an embodiment of the present application; Figure 18 is a structural schematic diagram of an electrode finger with the protective layer being a titanium layer according to an embodiment of the present application; Figure 19 is a schematic diagram of a multiplexer surface acoustic wave filter according to an embodiment of the present application. DETAILED DESCRIPTION

[0017] It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] In order for those skilled in the art to better understand the present disclosure scheme, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below in combination with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present disclosure.

[0019] It should be noted that the terms "first", "second", and the like in the description and in the claims of the present disclosure and the above-described drawings are used to distinguish similar objects and are not necessarily used to describe a particular sequential or chronological order. It should be understood that the terms as used in this way can be interchanged, where appropriate, to describe the embodiments of the present disclosure described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a list of steps or units is not necessarily limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to such processes, methods, products, or apparatuses.

[0020] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of the features, steps, operations, devices, components, and / or combinations thereof.

[0021] Figure 2 is a schematic diagram of a surface acoustic wave filter according to the present application. Referring to Figure 2 A surface acoustic wave filter 10 includes a first piezoelectric substrate 110 and a first interdigital transducer 120 disposed on the first piezoelectric substrate 110. The first interdigital transducer 120 includes a first bus bar 121 and a second bus bar 122 disposed opposite each other, a plurality of first electrode fingers 123 extending from the first bus bar 121 to the second bus bar 122, and a plurality of second electrode fingers 124 extending from the second bus bar 122 to the first bus bar 121. The plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 are disposed apart from each other. The plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 overlap each other and form a first overlap region 125. In the direction of propagation of the acoustic wave, the boundary shape of the first overlap region 125 conforms to a trigonometric function curve. The shape of the first bus bar 121 and the second bus bar 122 matches the boundary shape of the first overlap region 125.

[0022] In particular, referring to Figure 2 The surface acoustic wave filter 10 includes a first piezoelectric substrate 110 and a first interdigital transducer 120 disposed on the first piezoelectric substrate 110. The first interdigital transducer 120 includes a first bus bar 121 and a second bus bar 122 disposed opposite each other, a plurality of first electrode fingers 123 extending from the first bus bar 121 to the second bus bar 122, and a plurality of second electrode fingers 124 extending from the second bus bar 122 to the first bus bar 121.

[0023] Further, referring to Figure 2 As shown in FIG. 1, since the plurality of first electrode fingers 123 are extended from the first bus bar 121 to the second bus bar 122, the plurality of second electrode fingers 124 are extended from the second bus bar 122 to the first bus bar 121, and the plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 are arranged at intervals, the plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 can overlap each other and form a first overlap area 125. The upper boundary of the first overlap area 125 corresponds to the end of the plurality of continuous first electrode fingers 123. The lower boundary of the first overlap area 125 corresponds to the end of the plurality of continuous second electrode fingers 124.

[0024] It is worth noting that the boundary shape of the first overlap area 125 formed by the present application conforms to a trigonometric function curve. That is, the end of the plurality of continuous first electrode fingers 123 conforms to a trigonometric function curve (corresponding to the upper boundary of the first overlap area 125), and the end of the plurality of continuous second electrode fingers 124 conforms to a trigonometric function curve (corresponding to the lower boundary of the first overlap area 125). That is, when the plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 are made, the present application non-uniformly designs the overlap length of the plurality of first electrode fingers 123 and the plurality of second electrode fingers 124, so that the apodization of the plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 conforms to a trigonometric function curve, thereby effectively suppressing the transverse mode spur.

[0025] In addition, referring to Figure 1 and the background art, the existing first bus bar 121 and the second bus bar 122 are arranged in parallel, and there is a non-overlapping part between the first bus bar 121 and the overlapping part, and there is a non-overlapping part between the second bus bar 122 and the overlapping part. Different from the above prior art, the shape of the first bus bar 121 and the second bus bar 122 in the surface acoustic wave filter of the present application matches the boundary shape of the first overlap area 125, and there is no non-overlapping area between the first bus bar 121 and the first overlap area 125, and there is no non-overlapping area between the second bus bar 122 and the first overlap area 125. The first overlap area 125 corresponds to the effective area, and the non-overlapping area corresponds to the non-effective area.

[0026] That is, in the case where the shape of the first bus bar 121 and the second bus bar 122 matches the boundary shape of the first overlap area 125, the present application can reduce the non-effective area. Thus, the use efficiency of the surface acoustic wave filter can be effectively improved, and the small size surface acoustic wave filter can be realized.

[0027] As described in the background, although the existing surface acoustic wave filter effectively suppresses the transverse mode spur by using the apodization method, the formation of the non-overlapping part is prone to cause material waste because the effective area of the capacitance (i.e., the parasitic capacitance formed between the piezoelectric substrate and the interdigital transducer) is determined by the overlapping part of each first electrode finger and each second electrode finger, and the non-overlapping part is a non-effective area. Thus, it is not conducive to improve the use efficiency of the surface acoustic wave filter and the realization of the small-size surface acoustic wave filter.

[0028] Therefore, the present application provides a surface acoustic wave filter and a multiplexer surface acoustic wave filter. In the surface acoustic wave filter of the present application, the plurality of first electrode fingers and the plurality of second electrode fingers are mutually overlapped and form a first overlapping area with a boundary shape conforming to a trigonometric function curve. As described above, the boundary shape of the first overlapping area conforms to a trigonometric function curve, which means that the overlapping lengths of the plurality of first electrode fingers and the plurality of second electrode fingers used to form the first overlapping area are different. Thus, by non-uniformly designing the overlapping lengths of the plurality of first electrode fingers and the plurality of second electrode fingers, the transverse mode spur of the surface acoustic wave filter can be effectively suppressed.

[0029] In addition, since the shapes of the first bus bar and the second bus bar match the boundary shape of the first overlapping area, there is no non-effective area between the first bus bar and the first overlapping area, and between the second bus bar and the first overlapping area. That is, the effective area that can be used as a capacitance exists between the first bus bar and the second bus bar of the surface acoustic wave filter of the present application. Thus, the use efficiency of the surface acoustic wave filter can be effectively improved, and a small-size surface acoustic wave filter can be realized.

[0030] Furthermore, the technical problem that although the surface acoustic wave filter manufactured by using the apodization method can effectively suppress the transverse mode spur, the area of the non-effective area is large, which is not conducive to improve the use efficiency of the surface acoustic wave filter and the realization of the small-size surface acoustic wave filter is solved.

[0031] In addition, it is worth noting that the type of the surface acoustic wave filter in the present application includes but is not limited to a thin film surface acoustic wave filter (TF-SAW) or a temperature compensated surface acoustic wave filter (TC-SAW), which is not limited here.

[0032] Optionally, the ratio between the minimum value of the longitudinal overlapping length of the first electrode finger 123 and the second electrode finger 124 and the maximum value of the longitudinal overlapping length is less than or equal to 40%.

[0033] Specifically, referring to Figure 2As shown, because the boundary of the first overlap region 125 (including the upper boundary and the lower boundary) conforms to the trigonometric function curve in the direction of the sound wave propagation, the longitudinal length of the first overlap region 125 is not fixed but continuously changes. Thus, the longitudinal length of the first overlap region 125 has a maximum value and a minimum value, i.e., the longitudinal overlap length of the plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 has a maximum value and a minimum value.

[0034] In the present embodiment, the ratio between the minimum value of the longitudinal overlap length and the maximum value of the longitudinal overlap length is less than or equal to 40%.

[0035] Thus, by setting the ratio between the minimum value of the longitudinal overlap length and the maximum value of the longitudinal overlap length to be less than or equal to 40%, the area utilization of the effective region of the first SAW filter can be improved while suppressing the transverse mode spur.

[0036] Alternatively, the boundary length of the first overlap region 125 is greater than or equal to 0.4 periods of the trigonometric function curve.

[0037] Specifically, referring to Figure 2 As shown, the boundary of the first overlap region 125 conforms to the trigonometric function curve. In the present embodiment, the boundary length of the first overlap region 125 (including the upper boundary length and the lower boundary length) is greater than or equal to 0.4 periods of the trigonometric function curve. Thus, on this basis, the utilization rate of the effective region of the first SAW filter is maximized.

[0038] Optionally, the surface acoustic wave filter further comprises a first reflector 130 and a second reflector 140 respectively arranged on two sides of the first interdigital transducer 120. The first reflector 130 comprises a third bus bar 131, a fourth bus bar 132, and a plurality of third electrode fingers 133 connected to the third bus bar 131 and the fourth bus bar 132 respectively. The second reflector 140 comprises a fifth bus bar 141, a sixth bus bar 142, and a plurality of fourth electrode fingers 143 connected to the fifth bus bar 141 and the sixth bus bar 142 respectively. In the direction of the sound wave propagation, the shape of the third bus bar 131 corresponding to the first reflector 130 continues the shape of the first bus bar 121 and extends in the form of a trigonometric function curve. The shape of the fourth bus bar 132 corresponding to the first reflector 130 continues the shape of the second bus bar 122 and extends in the form of a trigonometric function curve. In the direction of the sound wave propagation, the shape of the fifth bus bar 141 corresponding to the second reflector 140 continues the shape of the first bus bar 121 and extends in the form of a trigonometric function curve. The shape of the sixth bus bar 142 corresponding to the second reflector 140 continues the shape of the second bus bar 122 and extends in the form of a trigonometric function curve.

[0039] In particular, referring to FIG. 1, Figure 2 As shown in FIG. 1, the surface acoustic wave filter further comprises a first reflector 130 and a second reflector 140 respectively arranged on two sides of the first interdigital transducer 120. The first reflector 130 comprises a third bus bar 131 and a fourth bus bar 132, and a plurality of third electrode fingers 133 connected between the third bus bar 131 and the fourth bus bar 132. The second reflector 140 comprises a fifth bus bar 141 and a sixth bus bar 142, and a plurality of fourth electrode fingers 143 connected between the fifth bus bar 141 and the sixth bus bar 142.

[0040] In addition, when the first reflector 130 is manufactured, the shape of the third bus bar 131 corresponding to the first reflector 130 continues the shape of the first bus bar 121 and extends in the form of a trigonometric function curve. The shape of the fourth bus bar 132 corresponding to the first reflector 130 continues the shape of the second bus bar 122 and extends in the form of a trigonometric function curve.

[0041] Therefore, in the case that the shape of the bus bars (including the third bus bar 131 and the fourth bus bar 132) of the first reflector 130 continues the shape of the bus bars (including the first bus bar 121 and the second bus bar 122) of the first interdigital transducer 120 and extends in the form of a trigonometric function curve, the continuity of the impedance characteristics of the surface acoustic wave during the propagation process can be ensured, and unnecessary scattering or energy loss of the sound wave can be avoided.

[0042] Similarly, when the second reflector 140 is manufactured, the shape of the fifth bus bar 141 corresponding to the second reflector 140 is continued from the shape of the first bus bar 121 and extends in the form of a trigonometric function curve. The shape of the sixth bus bar 142 corresponding to the second reflector 140 is continued from the shape of the second bus bar 122 and extends in the form of a trigonometric function curve.

[0043] Therefore, in the case that the shape of the bus bars (including the fifth bus bar 141 and the sixth bus bar 142) of the second reflector 140 is continued from the shape of the bus bars (including the first bus bar 121 and the second bus bar 122) of the first interdigital transducer 120 and extends in the form of a trigonometric function curve, the continuity of the impedance characteristics of the surface acoustic wave in the propagation process can be ensured, and unnecessary acoustic wave scattering or energy loss can be avoided.

[0044] Optionally, the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143 include a first adhesive layer, an auxiliary conductive layer, a plurality of conductive layers and a plurality of second adhesive layers arranged alternately, and a protective layer arranged in sequence from bottom to top.

[0045] Specifically, Figure 3 is a structural schematic diagram of an electrode finger of a surface acoustic wave filter according to an embodiment of the present application. Referring to Figure 3 As shown in the figure, when the surface acoustic wave filter is actually applied, in order to excite the surface acoustic wave, an electric field needs to be applied to the piezoelectric substrate 100 to make it vibrate periodically. However, since the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143 are metal materials, under high-frequency vibration, the metal atoms in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143 will migrate, thereby causing the power tolerance performance of the surface acoustic wave filter to decrease.

[0046] In order to solve the above-mentioned problems, the conductive layer in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143 is replaced by a plurality of conductive layers and a plurality of second adhesive layers arranged alternately. In this embodiment, the electrode fingers include the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143. And in this embodiment, the surface acoustic wave filter includes a first surface acoustic wave filter and a subsequently mentioned second surface acoustic wave filter.

[0047] Because the crystal structures of the conductive layer material and the second adhesion layer material differ significantly, the activation energy required for the diffusion of metal atoms in the conductive layer material is higher. Therefore, multiple second adhesion layers can act as physical barriers, separating the multiple conductive layers into independent regions, cutting off the long-range migration channels of metal atoms in the conductive layer material, forcing the diffusion path to detour, and significantly reducing the overall mobility of metal atoms in the conductive layer material. Thus, while reducing the overall mobility of metal atoms in the conductive layer material, the power withstand performance of the first surface acoustic wave filter can be effectively improved, and the overall quality of the first surface acoustic wave filter can be guaranteed.

[0048] Furthermore, this application splits the original conductive layer into three layers without changing the content of the conductive layer material. The thickness of each conductive layer is smaller than that of the original conductive layer. Therefore, while miniaturizing the first surface acoustic wave filter, it is still possible to reduce the mobility of metal atoms in the conductive layer material, thereby improving the power tolerance performance of the first surface acoustic wave filter.

[0049] Figure 4 A power comparison diagram is shown between the surface acoustic wave filter according to this embodiment and a conventional surface acoustic wave filter. Specifically, refer to... Figure 3 and Figure 4 As shown, this application replaces the conductive layers in the plurality of first electrode fingers 123, plurality of second electrode fingers 124, plurality of third electrode fingers 133, and plurality of fourth electrode fingers 143 in the prior art with a plurality of conductive layers and a plurality of second adhesive layers that are alternately arranged. Results obtained from testing on an Evaluation Board (EVB) show that the first surface acoustic wave filter (SAW filter) provided in this application (and...) Figure 4 The blue line in the image corresponds to (compared to) an unoptimized surface acoustic wave filter (and) Figure 4 (corresponding to the red line in the diagram), the input power that can be tolerated is increased by at least 1dB, thereby increasing the output power by at least 1dB.

[0050] Therefore, this application replaces the conductive layer in the prior art with multiple conductive layers and multiple second adhesive layers arranged alternately. The original conductive layer is split into three conductive layers, and two second adhesive layers are inserted between the three layers as physical barriers separating the conductive layers. The crystal structures of the conductive layer material and the second adhesive layer material differ significantly. Compared to the original conductive layer without second adhesive layers, the activation energy required for metal atom diffusion in the conductive layer material is higher. Therefore, the long-range migration channels of metal atoms are cut off, resulting in a significant reduction in the mobility of metal atoms.

[0051] Thus, the first surface acoustic wave filter provided in the application can reduce the mobility of metal atoms in the electrode fingers, and optimize the power tolerance performance of the surface acoustic wave filter. Thus, the technical problem of limited power tolerance performance of the surface acoustic wave filter caused by high mobility of metal atoms in the electrode fingers in the prior art is solved.

[0052] Optionally, the conductive layer is a copper layer.

[0053] Specifically, Figure 5 A structure diagram corresponding to the conductive layer being a copper layer according to the embodiment of the application is shown. Referring to Figure 5 As shown in the figure, among the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the material of the conductive layer is a copper material. The thickness ratio of the three conductive layers arranged from bottom to top, for example, can be 1:1:2.

[0054] Since the copper material has high conductivity and low resistivity, less heat is generated when the current flows. At the same time, the copper material has good thermal conductivity, which can achieve efficient heat dissipation and avoid local accumulation of heat in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143. Thus, the first surface acoustic wave filter can work stably at a higher current and power level, while the temperature remains within a safe range, thereby achieving high power tolerance performance of the device.

[0055] Optionally, the copper layer between the adjacent two second adhesive layers in the plurality of conductive layers is replaced by a silver layer.

[0056] Specifically, Figure 6 A structure diagram of the electrode finger with the conductive layer between the adjacent two second adhesive layers being a silver layer according to the embodiment of the application is shown. Referring to Figure 6 As shown in the figure, among the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the copper layer between the adjacent two second adhesive layers is replaced by a silver layer. That is, the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143 include a first adhesive layer, an auxiliary conductive layer, a copper layer, a second adhesive layer, a silver layer, a second adhesive layer and a protective layer stacked in order from bottom to top.

[0057] In the structural design of the electrode finger, the material selection and arrangement of each metal layer will directly affect the current distribution and heat dissipation efficiency, and thus affect the power tolerance performance of the surface acoustic wave filter.

[0058] Because silver has a lower resistivity than copper, embedding a silver layer between two adjacent second adhesion layers to form a current shunt structure can result in a more uniform current distribution, avoiding localized overheating caused by current congestion. Furthermore, silver's superior thermal conductivity allows for full utilization of its high thermal conductivity, enabling more efficient heat dissipation from the multiple first electrode fingers 123, second electrode fingers 124, third electrode fingers 133, and fourth electrode fingers 143. This avoids high atomic mobility in the conductive layer due to localized high temperatures, allowing the multiple first electrode fingers 123, second electrode fingers 124, third electrode fingers 133, and fourth electrode fingers 143 to withstand greater currents without failure, thus achieving the technical effect of optimizing the power withstand performance of the first surface acoustic wave filter.

[0059] Figure 7 This is a power comparison diagram of a surface acoustic wave (SAW) filter with a silver conductive layer and a SAW filter with a copper conductive layer, according to embodiments of this application. Specifically, refer to... Figure 6 and Figure 7 As shown, this application replaces the copper layer between two adjacent second adhesion layers in a plurality of first electrode fingers 123, a plurality of second electrode fingers 124, a plurality of third electrode fingers 133, and a plurality of fourth electrode fingers 143 with a silver layer. The thickness ratio of the three conductive layers, spaced apart from bottom to top, is 1:1:2. Results obtained from testing on an evaluation board show that, compared to surface acoustic wave filters without optimized conductive layer materials (and...),... Figure 7 (corresponding to the blue line in the image), the optimized first surface acoustic wave filter (and...) Figure 7 The green and red lines in the diagram correspond to the input power that the filter can withstand, which is increased by 1.61 dB, resulting in a 2 dB increase in output power. Furthermore, two experiments were conducted on the optimized first surface acoustic wave filter (compared to...). Figure 7 As shown in the diagram (corresponding to the green and red lines), it was found that the first surface acoustic wave filter's ability to withstand input power was improved and more stable.

[0060] Optionally, the copper layer located between two adjacent second adhesive layers in the plurality of conductive layers may be replaced with a platinum layer.

[0061] Specifically, Figure 8 A schematic diagram of an electrode finger, according to an embodiment of this application, is shown, in which a platinum layer forms the conductive layer between two adjacent second adhesion layers. (Reference) Figure 8As shown, among the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the copper layer between two adjacent second adhesive layers is replaced by a platinum layer. That is, the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143 include, from bottom to top, a first adhesive layer, an auxiliary conductive layer, a copper layer, a second adhesive layer, a platinum layer, a second adhesive layer and a protective layer.

[0062] Since copper material can form an oxide layer at the interface to increase the interface contact resistance, causing current crowding, causing local overheating of the electrode fingers, and the temperature rise will exacerbate the migration of metal atoms. The chemical inertness of platinum material makes the interface almost no oxidation, avoiding the temperature rise caused by the increase of interface contact resistance, and the high temperature resistance of platinum material is much better than that of copper material. Therefore, the platinum layer can share the current and reduce the generation of joule heat, thereby avoiding the high temperature caused by the high migration rate of metal atoms.

[0063] And the activation energy required for platinum atom migration is higher than that of copper atom, and the platinum layer can prevent the diffusion of metal atoms together with the first adhesive layer and the plurality of second adhesive layers. Thus, the migration rate of metal atoms in the conductive layer can be further reduced, and the power tolerance performance of the first surface acoustic wave filter can be improved.

[0064] Optionally, the conductive layer is a copper-aluminum alloy layer.

[0065] Specifically, Figure 9 A structure diagram corresponding to the conductive layer being a copper-aluminum alloy layer according to the embodiment is shown. Referring to Figure 9 As shown, among the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the material of the conductive layer is a copper-aluminum alloy material. That is, the copper material in the electrode fingers is replaced by a copper-aluminum alloy material.

[0066] In the case of replacing the copper material with a copper-aluminum alloy material, since the aluminum atoms in the copper-aluminum alloy material are dissolved in the copper lattice, the grain boundary is pinned to hinder the diffusion of copper atoms along the grain boundary, and therefore the lattice distortion caused by the different radii of aluminum atoms and copper atoms increases the energy barrier of dislocation movement. Thus, the activation energy required for metal atom migration is significantly improved, the migration rate of metal atoms is reduced, and the power tolerance performance of the first surface acoustic wave filter is improved.

[0067] Figure 10 A power comparison diagram of the surface acoustic wave filter according to the embodiment of the present application, in which the conductive layer is a copper-aluminum alloy layer, and the surface acoustic wave filter in which the conductive layer is a copper layer. Specifically, refer to Figure 9 and Figure 10As shown, the conductive layer in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143 is replaced by a copper-aluminum alloy layer. The thickness ratio of the three conductive layers arranged from bottom to top is 1:1:2. The results obtained by testing on the evaluation board show that, compared with the acoustic surface wave filter with unoptimized conductive layer material (corresponding to the blue line in Figure 10 ), the first acoustic surface wave filter after optimization (corresponding to the red line in Figure 10 ) can withstand an input power increase of 0.6 dB, so that the output power is increased by 0.5 dB.

[0068] Optionally, the conductive layer is a titanium-copper alloy layer.

[0069] Specifically, Figure 11 is a structural schematic diagram of an electrode finger with a conductive layer of a titanium-copper alloy layer according to an embodiment of the present application. Referring to Figure 11 , in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the material of the conductive layer is a titanium-copper alloy material. That is, the copper material in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143 is replaced by a titanium-copper alloy material.

[0070] In the case of replacing the copper material with a titanium-copper alloy material, since the titanium atoms in the titanium-copper alloy material are dissolved in the copper lattice, the pinning grain boundary hinders the diffusion of copper atoms along the grain boundary, so that the lattice distortion caused by the different radii of titanium atoms and copper atoms increases the energy barrier of dislocation motion. Thus, the activation energy required for metal atom migration is significantly increased, the mobility of metal atoms is reduced, and the power tolerance performance of the first acoustic surface wave filter is improved.

[0071] Optionally, the conductive layer is a molybdenum layer.

[0072] Specifically, Figure 12 is a structural schematic diagram of an electrode finger with a conductive layer of a molybdenum layer according to an embodiment of the present application. Referring to Figure 2 , in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the material of the conductive layer is a molybdenum material. That is, the copper material in the electrode finger is replaced by a molybdenum material.

[0073] Since copper material can form an oxide layer at the interface to increase the interface contact resistance, causing current crowding, local overheating of the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, and temperature rise can exacerbate the migration of metal atoms. And the resistivity of molybdenum trioxide generated after the oxidation of molybdenum material is lower than that of copper oxide, and molybdenum trioxide is usually a continuous thin film, which can inhibit continuous oxidation and thus avoid the increase of interface contact resistance. Therefore, the conductive layer of molybdenum material can share the current and reduce the generation of Joule heat, thereby avoiding the high temperature caused by the high migration rate of metal atoms.

[0074] The activation energy required for the migration of molybdenum atoms is higher than that of copper atoms. Embedding the first adhesive layer and the plurality of second adhesive layers in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143 can further reduce the migration rate of metal atoms, thereby improving the power tolerance performance of the first surface acoustic wave filter.

[0075] Optionally, the first adhesive layer and the plurality of second adhesive layers are chromium layers.

[0076] Specifically, Figure 13 is a structural schematic diagram of the electrode finger of the first adhesive layer and the second adhesive layer according to the embodiment of the present application. Referring to Figure 13 , in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the material of the first adhesive layer and the plurality of second adhesive layers is chromium material.

[0077] During the deposition process of the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the chromium atoms of the first adhesive layer can be bonded to the surface of the first piezoelectric substrate 110 and to the upper deposited auxiliary conductive layer, and the chromium atoms of the second adhesive layer can be bonded to the adjacent conductive layer. Thus, the firm bonding between the layers can be ensured, and the reliability and stability of the device can be enhanced.

[0078] At the same time, since the metal atoms of the conductive layer material will diffuse during the operation of the first surface acoustic wave filter, the plurality of second adhesive layers of chromium material can separate the plurality of conductive layers as independent areas, cut off the long-range migration channel of the metal atoms of the conductive layer material, and reduce the overall migration rate of the metal atoms of the conductive layer material. Thus, in the case of reducing the overall migration rate of the metal atoms of the conductive layer material, the power tolerance performance of the first surface acoustic wave filter can be effectively improved.

[0079] Optionally, the second adhesive layer is arranged adjacent to the auxiliary conductive layer.

[0080] Specifically,Figure 14 This is a schematic diagram of the structure of the electrode finger, according to an embodiment of this application, for removing the conductive layer located between the second adhesion layer and the auxiliary conductive layer. (Reference) Figure 14 As shown, the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143 include, from bottom to top, a first adhesive layer, an auxiliary conductive layer, a second adhesive layer, a conductive layer, another second adhesive layer, a conductive layer, and a protective layer, stacked sequentially. Specifically, the conductive layer between the auxiliary conductive layer and the second adhesive layer in the electrode fingers is removed. The conductive layer in the electrode fingers is made of copper, and the second adhesive layer is made of chromium.

[0081] Therefore, by removing the copper layer between the auxiliary conductive layer and the chromium layer, the propagation path of the surface acoustic wave is simplified, thereby reducing the energy loss of the surface acoustic wave scattered within the multiple first electrode fingers 123, multiple second electrode fingers 124, multiple third electrode fingers 133 and multiple fourth electrode fingers 143 of the multilayer structure.

[0082] Figure 15 As described in the embodiments of this application Figure 14 A power comparison chart of a surface acoustic wave (SAW) filter with and without the conductive layer removed. Specifically, refer to... Figure 14 and Figure 15 As shown, this application removes the conductive layer between the auxiliary conductive layer and the second adhesive layer in multiple first electrode fingers 123, multiple second electrode fingers 124, multiple third electrode fingers 133, and multiple fourth electrode fingers 143. The thickness ratio of the two conductive layers spaced apart from bottom to top is 1:3. Test results on the evaluation board show that, compared to the surface acoustic wave filter without optimized conductive layer structure (and...),... Figure 15 (corresponding to the blue line in the image), the optimized first surface acoustic wave filter (and...) Figure 15 The red line in the diagram indicates that the input power that the system can withstand is increased by 0.4dB, which in turn increases the output power by 0.4dB.

[0083] Optionally, the first adhesive layer is a titanium layer, and the plurality of second adhesive layers are chromium layers.

[0084] Specifically, Figure 16 This is a schematic diagram of the structure of an electrode finger with a first adhesion layer of titanium, according to an embodiment of this application. (Reference) Figure 16 As shown, the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143 include, from bottom to top, a titanium layer, an auxiliary conductive layer, a chromium layer, a conductive layer, another chromium layer, a conductive layer, and a protective layer. The conductive layer in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133, and the plurality of fourth electrode fingers 143 is made of copper.

[0085] Since the density of the titanium material is smaller than that of the chromium material, the thickness of the titanium layer in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143 is thicker under the same mass, which is conducive to heat dissipation during operation. Moreover, the titanium material has smaller acoustic impedance, which is more matched with the acoustic impedance of the first piezoelectric substrate 110, thereby reducing insertion loss. Thus, the first surface acoustic wave filter can reduce self-heating during operation, thereby improving the power tolerance performance of the first surface acoustic wave filter.

[0086] Optionally, the thickness of the first adhesive layer and each second adhesive layer is 1 nm to 10 nm.

[0087] Optionally, the auxiliary conductive layer is a silver layer.

[0088] Specifically, Figure 17 is a structural schematic diagram of an electrode finger with an auxiliary conductive layer being a silver layer according to an embodiment of the present application. Referring to Figure 17 In the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the material of the auxiliary conductive layer is silver material.

[0089] Since the silver material has high conductivity and low resistivity, less heat is generated when current flows. At the same time, the silver material has good thermal conductivity, which can achieve efficient heat dissipation and avoid local accumulation of heat in the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143. Moreover, the silver material is not easy to oxidize, thereby avoiding the increase of heat caused by the formation of a high-resistance oxide layer. Thus, the first surface acoustic wave filter can reduce self-heating during operation, thereby improving the power tolerance performance of the first surface acoustic wave filter.

[0090] Optionally, the protective layer is a titanium layer.

[0091] Specifically, Figure 18 is a structural schematic diagram of an electrode finger with a protective layer being a titanium layer according to an embodiment of the present application. Referring to Figure 18 In the plurality of first electrode fingers 123, the plurality of second electrode fingers 124, the plurality of third electrode fingers 133 and the plurality of fourth electrode fingers 143, the material of the protective layer is titanium material.

[0092] Since the titanium material is easy to oxidize to form a stable and dense oxide film, it can prevent oxygen from penetrating into the underlying conductive layer and protect the conductive layer from oxidation or corrosion. Thus, the device loss can be avoided, thereby ensuring the long-term power stability of the first surface acoustic wave filter under high power operation.

[0093] Meanwhile, the compact oxide film formed by oxidation of the titanium material can hinder surface diffusion of metal atoms of the conductive layer material, increase the activation energy required for migration of the metal atoms, thereby reducing the migration rate of the metal atoms, and further improve the power tolerance performance of the first surface acoustic wave filter.

[0094] According to another aspect of the present application, a multiplexer surface acoustic wave filter is also provided, comprising: a first surface acoustic wave filter 20 and a second surface acoustic wave filter 30 sharing the same first bus bar 121 with the first surface acoustic wave filter 20, wherein the first surface acoustic wave filter 20 comprises the above-mentioned surface acoustic wave filter 10, and the second surface acoustic wave filter 30 comprises: a second piezoelectric substrate 310 and a second interdigital transducer 320 disposed on the second piezoelectric substrate 310, wherein the second interdigital transducer 320 comprises: oppositely disposed first bus bar 121 and seventh bus bar 321, a plurality of fifth electrode fingers 322 extending from the first bus bar 121 to the seventh bus bar 321, and a plurality of sixth electrode fingers 323 extending from the seventh bus bar 321 to the first bus bar 121, and the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 are arranged at intervals with each other; the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 overlap each other and form a second overlapping area 324, wherein in the direction of sound wave propagation, the boundary shape of the second overlapping area 324 conforms to a trigonometric function curve, and the concave-convex parts of the first overlapping area 125 and the second overlapping area 324 are engaged with each other; and the shapes of the first bus bar 121 and the seventh bus bar 321 match the boundary shape of the second overlapping area 324.

[0095] Specifically, Figure 19 is a schematic diagram of a multiplexer surface acoustic wave filter according to an embodiment of the present application. Referring to Figure 19 As shown, the multiplexer surface acoustic wave filter comprises a first surface acoustic wave filter 20 and a second surface acoustic wave filter 30 sharing the same first bus bar 121 with the first surface acoustic wave filter 20. It is worth noting that in this embodiment, the multiplexer surface acoustic wave filter comprising the first surface acoustic wave filter 20 and the second surface acoustic wave filter 30 is integrally formed.

[0096] And the second surface acoustic wave filter 30 comprises a second piezoelectric substrate 310 and a second interdigital transducer 320 disposed on the second piezoelectric substrate 310. The second interdigital transducer 320 comprises oppositely disposed first bus bar 121 and seventh bus bar 321, a plurality of fifth electrode fingers 322 extending from the first bus bar 121 to the seventh bus bar 321, and a plurality of sixth electrode fingers 323 extending from the seventh bus bar 321 to the first bus bar 121.

[0097] Further, referring to Figure 19As shown, since the plurality of fifth electrode fingers 322 are led out from the first bus bar 121 and extend to the seventh bus bar 321, the plurality of sixth electrode fingers 323 are led out from the seventh bus bar 321 and extend to the first bus bar 121, and the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 are arranged at intervals from each other, the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 can overlap each other and form a second overlap area 324. Among them, the upper boundary of the second overlap area 324 corresponds to the end of the plurality of continuous fifth electrode fingers 322. The lower boundary of the second overlap area 324 corresponds to the end of the plurality of continuous sixth electrode fingers 323.

[0098] Notably, the boundary shape of the second overlap area 324 formed by the present application conforms to a trigonometric function curve. That is, the end of the plurality of continuous fifth electrode fingers 322 conforms to a trigonometric function curve (corresponding to the upper boundary of the second overlap area 324), and the end of the plurality of continuous sixth electrode fingers 323 conforms to a trigonometric function curve (corresponding to the lower boundary of the second overlap area 324). That is, in the present application, when the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 are made, the overlapping lengths of the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 are designed non-uniformly, so that the apodization of the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 conforms to a trigonometric function curve, thereby effectively suppressing the transverse mode spur.

[0099] In addition, since the first surface acoustic wave filter 20 and the second surface acoustic wave filter 30 share the same first bus bar 121, the part of the first overlap area 125 that is recessed corresponds to the part of the second overlap area 324 that is protruding, and the part of the first overlap area 125 that is protruding corresponds to the part of the second overlap area 324 that is recessed. That is, the concave-convex parts of the first overlap area 125 and the second overlap area 324 are engaged with each other.

[0100] And the shape of the first bus bar 121 in the second surface acoustic wave filter 30 matches the shape of the upper boundary of the second overlap area 324, and the shape of the seventh bus bar 321 matches the shape of the lower boundary of the second overlap area 324, so there is no non-overlapping area between the first bus bar 121 and the second overlap area 324, and there is no non-overlapping area between the seventh bus bar 321 and the second overlap area 324. Among them, the second overlap area 324 corresponds to an effective area, and the non-overlapping area corresponds to a non-effective area.

[0101] That is, in the case where the shapes of the first bus bar 121 and the seventh bus bar 321 match the boundary shapes of the second overlap area 324, the present application can reduce the non-effective area. Thus, the use efficiency of the multiplexer surface acoustic wave filter can be effectively improved, and the realization of a small-size multiplexer surface acoustic wave filter is achieved.

[0102] Optionally, a ratio between a minimum value of the longitudinal overlapping length of the first electrode fingers 123 and the second electrode fingers 124 and a maximum value of the longitudinal overlapping length of the fifth electrode fingers 322 and the sixth electrode fingers 323 is less than or equal to 40%; and a ratio between a minimum value of the longitudinal overlapping length of the fifth electrode fingers 322 and the sixth electrode fingers 323 and a maximum value of the longitudinal overlapping length of the first electrode fingers 123 and the second electrode fingers 124 is less than or equal to 40%.

[0103] Specifically, referring to FIG. 12, since the boundary (including the upper boundary and the lower boundary) of the first overlapping region 125 in the sound wave propagation direction conforms to a trigonometric function curve, the longitudinal length of the first overlapping region 125 is not fixed but continuously changes. Thus, the longitudinal length of the first overlapping region 125 has a maximum value and a minimum value, i.e., the longitudinal overlapping length of the plurality of first electrode fingers 123 and the plurality of second electrode fingers 124 has a maximum value and a minimum value. Figure 19 Similarly, since the boundary (including the upper boundary and the lower boundary) of the second overlapping region 324 in the sound wave propagation direction conforms to a trigonometric function curve, the longitudinal length of the second overlapping region 324 is not fixed but continuously changes. Thus, the longitudinal length of the second overlapping region 324 has a maximum value and a minimum value, and the longitudinal overlapping length of the plurality of fifth electrode fingers 322 and the plurality of sixth electrode fingers 323 has a maximum value and a minimum value.

[0104] In the embodiment, a ratio between a minimum value of the longitudinal overlapping length of the first electrode fingers 123 and the second electrode fingers 124 and a maximum value of the longitudinal overlapping length of the fifth electrode fingers 322 and the sixth electrode fingers 323 is less than or equal to 40%. A ratio between a minimum value of the longitudinal overlapping length of the fifth electrode fingers 322 and the sixth electrode fingers 323 and a maximum value of the longitudinal overlapping length of the first electrode fingers 123 and the second electrode fingers 124 is less than or equal to 40%.

[0105] Optionally, a period difference between the upper boundary of the first overlapping region 125 and the upper boundary of the second overlapping region 324 at a corresponding position is less than or equal to 40%; and a period difference between the lower boundary of the first overlapping region 125 and the lower boundary of the second overlapping region 324 at the corresponding position is less than or equal to 40%.

[0106] Specifically, referring to FIG. 12, the boundary shape of the first overlapping region 125 conforms to a trigonometric function curve, and the boundary shape of the second overlapping region 324 conforms to a trigonometric function curve. Thus, the boundary shape of the first overlapping region 125 and the second overlapping region 324 should satisfy the periodic variation trend of the trigonometric function curve.

[0107] Figure 19 Specifically, referring to FIG. 12, the boundary shape of the first overlapping region 125 conforms to a trigonometric function curve, and the boundary shape of the second overlapping region 324 conforms to a trigonometric function curve. Thus, the boundary shape of the first overlapping region 125 and the second overlapping region 324 should satisfy the periodic variation trend of the trigonometric function curve.

[0108] ​In the embodiment, a difference between the upper boundary of the first overlap region 125 and the upper boundary of the second overlap region 324 at the corresponding position is less than or equal to 40%.

[0109] Similarly, in the embodiment, a difference between the lower boundary of the first overlap region 125 and the lower boundary of the second overlap region 324 at the corresponding position is less than or equal to 40%.

[0110] Therefore, by the above structure, the area utilization of the effective region of the first surface acoustic wave filter and the area utilization of the effective region of the second surface acoustic wave filter can be improved while suppressing the transverse mode spurs.

[0111] Optionally, the second SAW filter further comprises a third reflector 330 and a fourth reflector 340 respectively arranged on two sides of the second IDT 320, and the third reflector 330 shares the third bus bar 131 with the first reflector 130, and the fourth reflector 340 shares the fifth bus bar 141 with the second reflector 140, wherein the third reflector 330 further comprises an eighth bus bar 331 arranged opposite to the third bus bar 131 and a plurality of seventh electrode fingers 332 connected to the third bus bar 131 and the eighth bus bar 331 respectively, and the fourth reflector 340 further comprises a ninth bus bar 341 arranged opposite to the fifth bus bar 141 and a plurality of eighth electrode fingers 342 connected to the fifth bus bar 141 and the ninth bus bar 341 respectively; in the direction of the sound wave propagation, the shape of the eighth bus bar 331 corresponding to the third reflector 330 continues the shape of the seventh bus bar 321 and extends in the form of a trigonometric function curve; and in the direction of the sound wave propagation, the shape of the ninth bus bar 341 corresponding to the fourth reflector 340 continues the shape of the seventh bus bar 321 and extends in the form of a trigonometric function curve.

[0112] Specifically, referring to FIG. 1, the second SAW filter 30 further comprises a third reflector 330 and a fourth reflector 340 respectively arranged on two sides of the second IDT 320. Figure 19 The third reflector 330 comprises a third bus bar 131 and an eighth bus bar 331, and a plurality of seventh electrode fingers 332 are connected between the third bus bar 131 and the eighth bus bar 331. The fourth reflector 340 comprises a fifth bus bar 141 and a ninth bus bar 341, and a plurality of eighth electrode fingers 342 are connected between the fifth bus bar 141 and the ninth bus bar 341.

[0113] In addition, when the third reflector 330 is manufactured, the shape of the third bus bar 131 corresponding to the third reflector 330 continues the shape of the first bus bar 121 and extends in the form of a trigonometric function curve. The shape of the eighth bus bar 331 corresponding to the third reflector 330 continues the shape of the seventh bus bar 321 and extends in the form of a trigonometric function curve.

[0114] Therefore, when the shape of the busbars of the third reflector 330 (including the third busbar 131 and the eighth busbar 331) continues the shape of the busbars of the second interdigital transducer 320 (the first busbar 121 and the seventh busbar 321), the continuity of the impedance characteristics of the surface acoustic wave during propagation can be ensured, and unnecessary sound wave scattering or energy loss can be avoided.

[0115] Similarly, in manufacturing the fourth reflector 340, the shape of the fifth busbar 141 corresponding to the fourth reflector 340 continues the shape of the first busbar 121 and extends in the form of a trigonometric function curve. The shape of the ninth busbar 341 corresponding to the fourth reflector 340 continues the shape of the seventh busbar 321 and extends in the form of a trigonometric function curve.

[0116] Therefore, when the shape of the busbars of the fourth reflector 340 (including the fifth busbar 141 and the ninth busbar 341) continues the shape of the busbars of the first interdigital transducer 120 (including the first busbar 121 and the seventh busbar 321) and extends in the form of a trigonometric function curve, the continuity of the impedance characteristics of the surface acoustic wave during propagation can be ensured, and unnecessary sound wave scattering or energy loss can be avoided.

[0117] Optionally, the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332 and the plurality of eighth electrode fingers 342 include a first adhesive layer, an auxiliary conductive layer, a plurality of conductive layers and a plurality of second adhesive layers arranged alternately from bottom to top, and a protective layer.

[0118] Specifically, refer to Figure 3 As shown, in practical applications of surface acoustic wave (SAW) filters, an electric field needs to be applied to the second piezoelectric substrate 310 to induce periodic vibrations in order to excite SAW waves. However, since the multiple fifth electrode fingers 322, the multiple sixth electrode fingers 323, the multiple seventh electrode fingers 332, and the multiple eighth electrode fingers 342 are made of metallic materials, under high-frequency vibrations, the metal atoms in these electrodes will migrate, resulting in a decrease in the power tolerance performance of the SAW filter.

[0119] To address the aforementioned problems, this application replaces the conductive layers in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 with a plurality of conductive layers and a plurality of second adhesive layers that are alternately arranged. In this embodiment, the electrode fingers include a plurality of fifth electrode fingers 322, a plurality of sixth electrode fingers 323, a plurality of seventh electrode fingers 332, and a plurality of eighth electrode fingers 342.

[0120] Wherein, since the crystal structure of the conductive layer material and the second adhesive layer material is quite different, the activation energy required for the metal atoms of the conductive layer material to diffuse is higher, therefore, the plurality of second adhesive layers can serve as a physical barrier to separate the plurality of conductive layers into independent regions, cut off the long-range migration channel of the metal atoms of the conductive layer material, force the diffusion path to detour, and significantly reduce the overall mobility of the metal atoms of the conductive layer material. Thus, in the case of reducing the overall mobility of the metal atoms of the conductive layer material, the power tolerance performance of the second surface acoustic wave filter can be effectively improved, and the overall quality of the second surface acoustic wave filter can be ensured.

[0121] In addition, the present application splits the original conductive layer into three layers, without changing the content of the conductive layer material, and the thickness of each conductive layer is smaller than that of the original conductive layer. Therefore, on the basis of the miniaturization of the second surface acoustic wave filter, the mobility of the metal atoms of the conductive layer material can still be reduced, thereby improving the power tolerance performance of the second surface acoustic wave filter.

[0122] Further, as shown in FIGS. 1A and 1B, the present application replaces the conductive layer in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 in the prior art with a plurality of conductive layers and a plurality of second adhesive layers arranged alternately. Figure 4 and Figure 5 The results of the test on the evaluation board (EVB) show that the second surface acoustic wave filter provided by the present application can withstand an input power of at least 1 dB higher than the unoptimized surface acoustic wave filter, thereby increasing the output power by at least 1 dB.

[0123] Therefore, the present application replaces the conductive layer in the prior art with a plurality of conductive layers and a plurality of second adhesive layers arranged alternately. The original conductive layer is split into three conductive layers, and two second adhesive layers are inserted between the three layers as a physical barrier to separate the conductive layers. The crystal structure of the conductive layer material and the second adhesive layer material is quite different, and the activation energy required for the metal atoms of the conductive layer material to diffuse is higher than that of the original conductive layer without the second adhesive layer. Therefore, the long-range migration channel of the metal atoms is cut off, and the mobility of the metal atoms is significantly reduced.

[0124] In other words, when the multiplexer surface acoustic wave (SAW) filter disclosed in this application includes an optimized first SAW filter and a second SAW filter, the mobility of metal atoms in the electrode fingers can be reduced, thereby optimizing the power handling performance of the first and second SAW filters in the multiplexer SAW filter. This solves the technical problem in the prior art where the high mobility of metal atoms in the electrode fingers leads to limited power handling performance of the SAW filter.

[0125] Optionally, the conductive layer is a copper layer.

[0126] Specifically, refer to Figure 5 As shown, in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, the conductive layer is made of copper. The thickness ratio of the three conductive layers, spaced apart from bottom to top, can be, for example, 1:1:2.

[0127] Because copper has high conductivity and low resistivity, less heat is generated when current flows through it. Simultaneously, copper's good thermal conductivity enables efficient heat dissipation, preventing localized heat buildup in the multiple fifth electrode fingers 322, sixth electrode fingers 323, seventh electrode fingers 332, and eighth electrode fingers 342. This allows the second surface acoustic wave filter to operate stably at higher current and power levels while maintaining a safe temperature range, thus achieving high power tolerance performance.

[0128] Optionally, the copper layer located between two adjacent second adhesion layers in the plurality of conductive layers may be replaced with a silver layer.

[0129] Specifically, refer to Figure 6 As shown, in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, the copper layer located between two adjacent second adhesion layers is replaced with a silver layer. That is, the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 include a first adhesion layer, an auxiliary conductive layer, a copper layer, a second adhesion layer, a silver layer, a second adhesion layer, and a protective layer stacked sequentially from bottom to top.

[0130] In the structural design of the electrode fingers, the material selection and arrangement of each metal layer will directly affect the current distribution and heat dissipation efficiency, and thus affect the power tolerance performance of the second surface acoustic wave filter.

[0131] Because silver has a lower resistivity than copper, embedding a silver layer between two adjacent second adhesion layers to form a current shunt structure can result in a more uniform current distribution, avoiding localized overheating caused by current congestion. Furthermore, silver's superior thermal conductivity allows for efficient heat dissipation by fully utilizing the multiple fifth electrode fingers 322, 323, 332, and 342. This avoids high atomic mobility in the conductive layer due to localized high temperatures, enabling the multiple fifth electrode fingers 322, 323, 332, and 342 to withstand greater currents without failure, thus optimizing the power handling performance of the two surface acoustic wave (SAW) filter.

[0132] Further, refer to Figure 6 and Figure 7 As shown, in this application, the copper layer located between two adjacent second adhesion layers in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 is replaced with a silver layer. The thickness ratio of the three conductive layers, spaced apart from bottom to top, is 1:1:2. Test results on an evaluation board show that, compared to the unoptimized surface acoustic wave filter with conductive layer material, the optimized second surface acoustic wave filter can withstand 1.61 dB more input power, resulting in a 2 dB increase in output power.

[0133] Optionally, the copper layer located between two adjacent second adhesive layers in the plurality of conductive layers may be replaced with a platinum layer.

[0134] Specifically, refer to Figure 8 As shown, in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, the copper layer located between two adjacent second adhesive layers is replaced with a platinum layer. That is, the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 include a first adhesive layer, an auxiliary conductive layer, a copper layer, a second adhesive layer, a platinum layer, a second adhesive layer, and a protective layer stacked sequentially from bottom to top.

[0135] Copper materials can form an oxide layer at the interface, increasing interfacial contact resistance, causing current congestion, and leading to localized overheating of the electrode. This temperature rise exacerbates metal atom migration. Platinum, on the other hand, is chemically inert, resulting in almost no oxidation at its interface, thus avoiding the temperature rise caused by increased interfacial contact resistance. Furthermore, platinum's high-temperature resistance is far superior to that of copper. Therefore, the platinum layer can distribute the current, reducing Joule heating and preventing high metal atom migration rates caused by localized high temperatures.

[0136] Furthermore, the activation energy required for platinum atom migration is higher than that for copper atoms. The platinum layer, together with the first adhesion layer and multiple second adhesion layers, can prevent metal atom diffusion. This further reduces the mobility of metal atoms in the conductive layer, thereby improving the power tolerance performance of the second surface acoustic wave filter.

[0137] Optionally, the conductive layer is a copper-aluminum alloy layer.

[0138] Specifically, refer to Figure 9 As shown, in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, the conductive layer is made of a copper-aluminum alloy. That is, the copper material in the electrode fingers is replaced with a copper-aluminum alloy.

[0139] When copper is replaced by a copper-aluminum alloy, the aluminum atoms in the alloy dissolve in the copper lattice, pinning grain boundaries and hindering the diffusion of copper atoms along these boundaries. Therefore, the lattice distortion caused by the difference in radii between aluminum and copper atoms increases the energy barrier for dislocation motion. This significantly increases the activation energy required for metal atom migration, reduces the metal atom mobility, and thus improves the power tolerance performance of the surface acoustic wave filter 10.

[0140] Further, refer to Figure 9 and Figure 10 As shown, in this application, the conductive layers in multiple fifth electrode fingers 322, multiple sixth electrode fingers 323, multiple seventh electrode fingers 332, and multiple eighth electrode fingers 342 are replaced with copper layers to form copper-aluminum alloy layers. The thickness ratio of the three conductive layers, spaced apart from bottom to top, is 1:1:2. Test results on an evaluation board show that, compared to the unoptimized surface acoustic wave (SAW) filter with the optimized conductive layer material, the optimized second SAW filter can withstand 0.6 dB more input power, resulting in a 0.5 dB increase in output power.

[0141] Optionally, the conductive layer is a titanium-copper alloy layer.

[0142] Specifically, refer to Figure 11 As shown, in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, the material of the conductive layer is a titanium-copper alloy. That is, the copper material in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 is replaced with a titanium-copper alloy.

[0143] In the case of replacing the copper material with the titanium-copper alloy material, since the titanium atoms in the titanium-copper alloy material are dissolved in the copper crystal lattice, the pinned grain boundaries hinder the diffusion of copper atoms along the grain boundaries, and thus the lattice distortion caused by the different radii of titanium atoms and copper atoms increases the energy barrier of dislocation movement. Therefore, the activation energy required for metal atom migration is significantly increased, the metal atom mobility is reduced, and the power tolerance performance of the second surface acoustic wave filter is improved.

[0144] Optionally, the conductive layer is a molybdenum layer.

[0145] Specifically, referring to FIG. 3, in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, the material of the conductive layer is a molybdenum material. That is, the copper material in the electrode fingers is replaced with a molybdenum material. Figure 12

[0146] Since the copper material can form an oxide layer at the interface to increase the interface contact resistance, causing current crowding, local overheating of the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, and the temperature rise will exacerbate the migration of metal atoms. The resistivity of molybdenum trioxide generated after oxidation of the molybdenum material is lower than that of the oxide of the copper material, and the molybdenum trioxide is usually a continuous thin film, which can inhibit continuous oxidation, thereby avoiding the increase of the interface contact resistance. Therefore, the conductive layer of the molybdenum material can share the current and reduce the generation of Joule heat, thereby avoiding the high metal atom mobility caused by local high temperature.

[0147] The activation energy required for the migration of molybdenum atoms is higher than that of copper atoms, and the embedding of the first adhesive layer and the plurality of second adhesive layers in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 can further reduce the metal atom mobility, thereby improving the power tolerance performance of the second surface acoustic wave filter.

[0148] Optionally, the first adhesive layer and the plurality of second adhesive layers are chromium layers.

[0149] Specifically, referring to FIG. 3, in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342, the material of the first adhesive layer and the plurality of second adhesive layers is a chromium material. Figure 13

[0150] ​​During the deposition of multiple fifth electrode fingers 322, multiple sixth electrode fingers 323, multiple seventh electrode fingers 332, and multiple eighth electrode fingers 342, chromium atoms in the first adhesion layer can bond to the surface of the second piezoelectric substrate 310 and to the upper deposited auxiliary conductive layer. Furthermore, chromium atoms in the second adhesion layer can bond to adjacent conductive layers. This ensures a strong bond between the layers, enhancing the reliability and stability of the device.

[0151] Meanwhile, since the metal atoms of the conductive layer material diffuse during the operation of the second surface acoustic wave filter, the multiple chromium-based second adhesion layers act as physical barriers, separating the multiple conductive layers into independent regions. This cuts off the long-range migration channels of the metal atoms in the conductive layer material, reducing the overall mobility of the metal atoms. Therefore, by reducing the overall mobility of the metal atoms in the conductive layer material, the power withstand performance of the second surface acoustic wave filter can be effectively improved.

[0152] Optionally, the second adhesive layer is disposed adjacent to the auxiliary conductive layer.

[0153] Specifically, refer to Figure 14 As shown, the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 include, from bottom to top, a first adhesive layer, an auxiliary conductive layer, a second adhesive layer, a conductive layer, another second adhesive layer, a conductive layer, and a protective layer, stacked sequentially. Specifically, the conductive layer between the auxiliary conductive layer and the second adhesive layer in the electrode finger is removed. The conductive layer in the electrode finger is made of copper, and the second adhesive layer is made of chromium.

[0154] Therefore, by removing the copper layer between the auxiliary conductive layer and the chromium layer, the propagation path of the surface acoustic wave is simplified, thereby reducing the energy loss of the surface acoustic wave scattered within the multiple fifth electrode fingers 322, multiple sixth electrode fingers 323, multiple seventh electrode fingers 332 and multiple eighth electrode fingers 342 of the multilayer structure.

[0155] Further, refer to Figure 14 and Figure 15 As shown, this application removes the conductive layer between the auxiliary conductive layer and the second adhesive layer in multiple fifth electrode fingers 322, multiple sixth electrode fingers 323, multiple seventh electrode fingers 332, and multiple eighth electrode fingers 342. The thickness ratio of the two conductive layers spaced apart from bottom to top is 1:3. Test results on an evaluation board show that, compared to the surface acoustic wave filter without optimized conductive layer structure, the optimized second surface acoustic wave filter can withstand 0.4 dB more input power, resulting in a 0.4 dB increase in output power.

[0156] Optionally, the first adhesive layer is a titanium layer, and the plurality of second adhesive layers are chromium layers.

[0157] Specifically, refer to Figure 16 As shown, the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 include, from bottom to top, a titanium layer, an auxiliary conductive layer, a chromium layer, a conductive layer, another chromium layer, a conductive layer, and a protective layer. The conductive layer in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332, and the plurality of eighth electrode fingers 342 is made of copper.

[0158] Because titanium has a lower density than chromium, the titanium layers in the multiple fifth electrode fingers 322, sixth electrode fingers 323, seventh electrode fingers 332, and eighth electrode fingers 342 can be thicker for the same mass, which is beneficial for heat dissipation during operation. Furthermore, titanium has a lower acoustic impedance, resulting in better acoustic impedance matching with the second piezoelectric substrate 310 and reduced insertion loss. This reduces self-heating of the second surface acoustic wave filter during operation, thereby improving its power handling performance.

[0159] Optionally, the thickness of the first adhesive layer and each of the second adhesive layers is 1 nm to 10 nm.

[0160] Optionally, the auxiliary conductive layer is a silver layer.

[0161] Specifically, refer to Figure 17 As shown, among the multiple fifth electrode fingers 322, multiple sixth electrode fingers 323, multiple seventh electrode fingers 332 and multiple eighth electrode fingers 342, the material of the auxiliary conductive layer is silver.

[0162] Because silver has high conductivity and low resistivity, it generates less heat when current flows through it. Simultaneously, silver's good thermal conductivity enables efficient heat dissipation, preventing localized heat buildup in the multiple fifth electrode fingers 322, sixth electrode fingers 323, seventh electrode fingers 332, and eighth electrode fingers 342. Furthermore, silver is not easily oxidized, avoiding the formation of a high-resistivity oxide layer that would lead to increased heat. This reduces the self-heating of the second surface acoustic wave filter during operation, thereby improving its power handling performance.

[0163] Optionally, the protective layer is a titanium layer.

[0164] Specifically, refer to Figure 18 As shown, the protective layer in the plurality of fifth electrode fingers 322, the plurality of sixth electrode fingers 323, the plurality of seventh electrode fingers 332 and the plurality of eighth electrode fingers 342 is made of titanium.

[0165] Since the titanium material is easy to be oxidized to form a stable and dense oxide film, the oxygen can be prevented from permeating to the underlying conductive layer, thereby protecting the conductive layer from being oxidized or corroded. Thus, the device loss can be avoided, and the long-term power stability of the second surface acoustic wave filter under high-power working can be ensured.

[0166] Meanwhile, the dense oxide film formed by the oxidation of the titanium material can hinder the surface diffusion of the metal atoms of the conductive layer material, increase the activation energy required for the migration of the metal atoms, and thus reduce the migration rate of the metal atoms, thereby improving the power tolerance performance of the second surface acoustic wave filter.

[0167] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure, unless otherwise specified. Meanwhile, it should be understood that the sizes of the various parts shown in the drawings are not drawn in accordance with the actual proportional relationship for the convenience of description. The techniques, methods, and devices known to those skilled in the related art can not be discussed in detail, but should be considered as part of the authorized description, if appropriate. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0168] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper", and the like can be used herein to describe the spatial positional relationship of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device as described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0169] In the description of the present disclosure, it is understood that the orientation words such as "front, back, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate and imply that the devices or elements referred to must have a particular orientation or be constructed and operated in a particular orientation, unless otherwise stated, and therefore cannot be understood as a limitation on the protection scope of the present disclosure; the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component itself.

[0170] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A surface acoustic wave filter (10) comprising: The first piezoelectric substrate (110) and the first interdigital transducer (120) disposed on the first piezoelectric substrate (110) are characterized in that the first interdigital transducer (120) comprises: oppositely disposed first bus bars (121) and second bus bars (122), a plurality of first electrode fingers (123) extending from the first bus bars (121) to the second bus bars (122), and a plurality of second electrode fingers (124) extending from the second bus bars (122) to the first bus bars (121), and the plurality of first electrode fingers (123) and the plurality of second electrode fingers (124) are disposed at intervals from each other; The plurality of first electrode fingers (123) and the plurality of second electrode fingers (124) overlap each other and form a first overlapping area (125), wherein in the sound wave propagation direction, the boundary shape of the first overlapping area (125) conforms to a trigonometric function curve; and The shapes of the first bus bars (121) and the second bus bars (122) match the boundary shape of the first overlapping area (125).

2. The surface acoustic wave filter according to claim 1, characterized by, The ratio between the minimum value and the maximum value of the longitudinal overlapping length of the first electrode fingers (123) and the second electrode fingers (124) is less than or equal to 40%.

3. The surface acoustic wave filter according to claim 1, characterized by, The boundary length of the first overlapping area (125) is greater than or equal to 0.4 periods of the trigonometric function curve.

4. The surface acoustic wave filter according to claim 1, characterized by, Further comprising: First and second reflectors (130) and (140) respectively disposed on both sides of the first interdigital transducer (120), wherein The first reflector (130) comprises third bus bars (131), fourth bus bars (132), and a plurality of third electrode fingers (133) connected to the third bus bars (131) and the fourth bus bars (132) respectively, and the second reflector (140) comprises fifth bus bars (141), sixth bus bars (142), and a plurality of fourth electrode fingers (143) connected to the fifth bus bars (141) and the sixth bus bars (142) respectively; In the sound wave propagation direction, the shape of the third bus bar (131) corresponding to the first reflector (130) continues the shape of the first bus bar (121) and extends in the form of a trigonometric function curve, and the shape of the fourth bus bar (132) corresponding to the first reflector (130) continues the shape of the second bus bar (122) and extends in the form of a trigonometric function curve; And In the sound wave propagation direction, the shape of the fifth bus bar (141) corresponding to the second reflector (140) continues the shape of the first bus bar (121) and extends in the form of a trigonometric function curve, and the shape of the sixth bus bar (142) corresponding to the second reflector (140) continues the shape of the second bus bar (122) and extends in the form of a trigonometric function curve.

5. The surface acoustic wave filter according to claim 4, wherein The plurality of first electrode fingers (123), the plurality of second electrode fingers (124), the plurality of third electrode fingers (133) and the plurality of fourth electrode fingers (143) comprise a first adhesive layer, an auxiliary conductive layer, a plurality of conductive layers and a plurality of second adhesive layers arranged alternately from bottom to top, and a protective layer.

6. A multiplexer surface acoustic wave filter characterized by comprising: Comprise: A first surface acoustic wave filter (20) and a second surface acoustic wave filter (30) sharing a same first bus bar (121) with the first surface acoustic wave filter (20), wherein the first surface acoustic wave filter (20) comprises the surface acoustic wave filter (10) of claim 5, and The second surface acoustic wave filter (30) comprises a second piezoelectric substrate (310) and a second interdigital transducer (320) disposed on the second piezoelectric substrate (310), wherein the second interdigital transducer (320) comprises a first bus bar (121) and a seventh bus bar (321) disposed oppositely, a plurality of fifth electrode fingers (322) extending from the first bus bar (121) to the seventh bus bar (321), and a plurality of sixth electrode fingers (323) extending from the seventh bus bar (321) to the first bus bar (121), and the plurality of fifth electrode fingers (322) and the plurality of sixth electrode fingers (323) are arranged alternately; The plurality of fifth electrode fingers (322) and the plurality of sixth electrode fingers (323) overlap each other and form a second overlapping area (324), wherein in the direction of sound wave propagation, the boundary shape of the second overlapping area (324) conforms to a trigonometric function curve, and the first overlapping area (125) and the concave-convex part of the second overlapping area (324) are engaged with each other; and The shape of the first bus bar (121) and the seventh bus bar (321) matches the boundary shape of the second overlapping area (324).

7. The multiplexer SAW filter according to claim 6, characterized in that The ratio between the minimum value of the longitudinal overlapping length of the first electrode finger (123) and the second electrode finger (124) and the maximum value of the longitudinal overlapping length of the fifth electrode finger (322) and the sixth electrode finger (323) is less than or equal to 40%; and The ratio between the minimum value of the longitudinal overlapping length of the fifth electrode finger (322) and the sixth electrode finger (323) and the maximum value of the longitudinal overlapping length of the first electrode finger (123) and the second electrode finger (124) is less than or equal to 40%.

8. The multiplexer SAW filter according to claim 7, characterized in that, The difference between the upper boundary of the first overlapping area (125) and the period of the upper boundary of the second overlapping area (324) at the corresponding position is less than or equal to 40%; and The difference between the lower boundary of the first overlapping area (125) and the period of the lower boundary of the second overlapping area (324) at the corresponding position is less than or equal to 40%. Further comprise:

9. The multiplexer SAW filter according to claim 8, characterized in that ​ A third reflector (330) and a fourth reflector (340) are respectively arranged on both sides of the second interdigital transducer (320), and the third reflector (330) shares a third bus bar (131) with the first reflector (130), and the fourth reflector (340) shares a fifth bus bar (141) with the second reflector (140), wherein The third reflector (330) further comprises an eighth bus bar (331) arranged opposite to the third bus bar (131) and a plurality of seventh electrode fingers (332) respectively connected to the third bus bar (131) and the eighth bus bar (331), and the fourth reflector (340) further comprises a ninth bus bar (341) arranged opposite to the fifth bus bar (141) and a plurality of eighth electrode fingers (342) respectively connected to the fifth bus bar (141) and the ninth bus bar (341); In the sound wave propagation direction, the shape of the eighth bus bar (331) corresponding to the third reflector (330) continues the shape of the seventh bus bar (321) and extends in the form of a trigonometric function curve; And In the sound wave propagation direction, the shape of the ninth bus bar (341) corresponding to the fourth reflector (340) continues the shape of the seventh bus bar (321) and extends in the form of a trigonometric function curve.

10. The multiplexer SAW filter of claim 9, wherein, The plurality of fifth electrode fingers (322), the plurality of sixth electrode fingers (323), the plurality of seventh electrode fingers (332) and the plurality of eighth electrode fingers (342) comprise a first adhesive layer, an auxiliary conductive layer, a plurality of conductive layers and a plurality of second adhesive layers arranged alternately, and a protective layer arranged in order from bottom to top.

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