Surface acoustic wave resonator, surface acoustic wave filter, and multiplexer

Abstract

A surface acoustic wave resonator (1) includes at least one electrode (4) disposed on a substrate (3) and including an IDT electrode (41), and a plurality of load members (51) disposed separately from each other on or in the substrate (3) and composed of a dielectric, each of the plurality of load members (51) at least partially overlapping at least one electrode finger in a plan view of the substrate (3), the number of electrode fingers overlapping the plurality of load members (51) disposed in a first sub-region (3b1) and the number of electrode fingers overlapping the plurality of load members (51) disposed in a third sub-region (3b3) are each greater than the number of electrode fingers overlapping the plurality of load members (51) disposed in a second sub-region (3b2), and the plurality of load members (51) include two or more load members (51) overlapping the electrode fingers disposed in the first sub-region (3b1) and two or more load members (51) overlapping the electrode fingers disposed in the third sub-region (3b3).

Description

Technical Field

[0001] This invention relates to surface acoustic wave resonators, surface acoustic wave filters, and multiplexers. Background Technology

[0002] Patent Document 1 discloses a surface acoustic wave filter that improves the Q value (quality factor), an indicator of the sharpness of the resonance peak, by using a substrate formed by a stack of a high-velocity support substrate, a low-velocity layer and a piezoelectric layer.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2012 / 086639 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, in previous surface acoustic wave (SAW) filters, further improvement in the Q value is desired.

[0008] Therefore, the present invention provides a surface acoustic wave resonator, surface acoustic wave filter or multiplexer that can improve the Q value.

[0009] Technical solutions for solving the problem

[0010] One aspect of the present invention relates to a surface acoustic wave resonator comprising: a substrate including a piezoelectric layer; at least one electrode disposed on the substrate, including an IDT electrode; and a plurality of first load members disposed separately on or within the substrate, comprising a dielectric material. The at least one electrode includes: a plurality of electrode fingers arranged along a first axis on the substrate and extending along a second axis perpendicular to the first axis. Each of the plurality of first load members, when viewed from above the substrate, at least partially overlaps with a corresponding at least one electrode finger. The number of electrode fingers overlapping with the plurality of first load members among the electrode fingers disposed in a first sub-region and the number of electrode fingers disposed in a third sub-region are further specified. The number of electrode fingers in the sub-region that overlap with the plurality of first load members is greater than the number of electrode fingers in the second sub-region that overlap with the plurality of first load members. The first sub-region, the second sub-region, and the third sub-region are obtained by equally dividing the region on the substrate where the plurality of electrode fingers are disposed in the direction of the second axis. The second sub-region is located between the first sub-region and the third sub-region. The plurality of first load members includes two or more first load members that overlap with the electrode fingers disposed in the first sub-region and two or more first load members that overlap with the electrode fingers disposed in the third sub-region.

[0011] One aspect of the present invention relates to a surface acoustic wave filter comprising at least one series arm resonator and at least one parallel arm resonator, wherein at least one of the at least one series arm resonator and at least one parallel arm resonator is the aforementioned surface acoustic wave resonator.

[0012] One aspect of the present invention relates to a multiplexer comprising: a transmit filter connected between an antenna connection terminal and a PA connection terminal, having a passband that includes a transmit band of a given frequency band; and a receive filter connected between an antenna connection terminal and an LNA connection terminal, having a passband that includes a receive band of the given frequency band, wherein at least one of the transmit filter and the receive filter is the aforementioned surface acoustic wave filter.

[0013] One aspect of the present invention relates to a surface acoustic wave resonator comprising: a substrate including a piezoelectric layer; at least one electrode disposed on the substrate including an IDT electrode; and a dielectric film disposed on the at least one electrode, wherein the at least one electrode includes: a plurality of electrode fingers arranged on the substrate along a first axis and extending along a second axis perpendicular to the first axis, wherein the average thickness of the dielectric film disposed on the electrode fingers in a first sub-region and the average thickness of the dielectric film disposed on the electrode fingers in a third sub-region are respectively greater than the average thickness of the dielectric film disposed on the electrode fingers in a second sub-region, wherein the first sub-region, the second sub-region, and the third sub-region are obtained by equally dividing the region on the substrate in which the plurality of electrode fingers are disposed in the direction of the second axis, and the second sub-region is located between the first sub-region and the third sub-region.

[0014] Invention Effects

[0015] According to the present invention, a surface acoustic wave resonator, surface acoustic wave filter, or multiplexer that can improve the Q value can be provided. Attached Figure Description

[0016] Figure 1 This is a top view of the surface acoustic wave resonator according to Embodiment 1.

[0017] Figure 2 This is a cross-sectional view of the surface acoustic wave resonator according to Embodiment 1.

[0018] Figure 3 This is a partial cross-sectional view of the surface acoustic wave resonator according to Embodiment 1.

[0019] Figure 4 This is a partial cross-sectional view of the surface acoustic wave resonator according to Embodiment 1.

[0020] Figure 5 This is a top view of the multiple electrodes and multiple load components involved in Embodiment 1.

[0021] Figure 6This is a graph showing the frequency characteristics of the Q value of the surface acoustic wave resonator involved in Example 1 and Comparative Example 1.

[0022] Figure 7 The graph shows the resonant characteristics of the surface acoustic wave resonators involved in Example 1 and Comparative Example 2.

[0023] Figure 8 The graph shows the resonant characteristics of the surface acoustic wave resonators involved in Example 1 and Comparative Example 3.

[0024] Figure 9 This is a graph showing the frequency characteristics of the Q values ​​of the surface acoustic wave resonators involved in Example 2 and Comparative Example 4.

[0025] Figure 10 This is a cross-sectional view of a surface acoustic wave resonator according to a variation of embodiment 1.

[0026] Figure 11 This is a top view of multiple electrodes and multiple load members involved in a variation of embodiment 1, Example 2.

[0027] Figure 12 This is a top view of the electrode and multiple load members involved in variation 3 of embodiment 1.

[0028] Figure 13 This is a top view of multiple electrodes and multiple load members involved in variation 4 of embodiment 1.

[0029] Figure 14 This is a partial cross-sectional view of a surface acoustic wave resonator involved in variation 4 of embodiment 1.

[0030] Figure 15 This is a top view of a surface acoustic wave resonator according to a variation of embodiment 1, example 5.

[0031] Figure 16 This is a cross-sectional view of a surface acoustic wave resonator according to a variation of embodiment 1, example 5.

[0032] Figure 17 This is a circuit diagram of the surface acoustic wave filter according to embodiment 2.

[0033] Figure 18 This is a top view of the surface acoustic wave filter according to Embodiment 2.

[0034] Figure 19 This is the circuit structure diagram of the multiplexer involved in Implementation Method 3. Detailed Implementation

[0035] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the embodiments described below are either general or specific examples. The numerical values, shapes, materials, constituent elements, arrangements of constituent elements, and connection methods shown in the following embodiments are examples and are not intended to limit the scope of the present invention.

[0036] Furthermore, the figures are schematic diagrams that have been appropriately emphasized, omitted, or proportionally adjusted for the purpose of illustrating the invention, and are not necessarily rigorous illustrations. Sometimes they differ from the actual shapes, positional relationships, and proportions. In the figures, substantially identical structures are labeled with the same reference numerals, and sometimes repeated descriptions are omitted or simplified.

[0037] In the following figures, the x-axis and y-axis are mutually orthogonal axes on a plane parallel to the main surface of the substrate. Specifically, the x-axis is the axis along which the plurality of electrodes disposed on the substrate are arranged, and is sometimes also represented as the propagation direction of the surface acoustic wave. The y-axis is the axis along which each of the plurality of electrodes disposed on the substrate extends. Furthermore, the z-axis is an axis perpendicular to the main surface of the substrate, with its positive direction representing the upward direction and its negative direction representing the downward direction.

[0038] In this disclosure, the term "connection" includes not only direct connections via connection terminals and / or wiring conductors, but also connections via other circuit elements. "Direct connection" means a direct connection via connection terminals and / or wiring conductors without the use of other circuit elements. "C connected between A and B" means that one end of C is connected to A and the other end of C is connected to B, and that C is configured in series in the path connecting A and B. "The path connecting A and B" means a path formed by conductors electrically connecting A to B.

[0039] The term "terminal" refers to the point where a conductor within an element terminates. Furthermore, when the impedance between conductors in an element is sufficiently low, a terminal can be interpreted not only as a single point, but also as any point on the conductor between elements or the entire conductor.

[0040] The "passband" of a bandpass filter is the portion of the spectrum transmitted through the filter, defined as the frequency band where the output power does not decrease by more than 3dB compared to the maximum output power. Therefore, the high-frequency and low-frequency ends of the passband of a bandpass filter are determined as the higher and lower frequencies of the two points where the output power decreases by 3dB compared to the maximum output power.

[0041] The term "receive band" refers to the frequency band used for receiving signals in a communication device, while the term "transmit band" refers to the frequency band used for transmitting signals. For example, if the frequency band is used for Frequency Division Duplex (FDD), then different frequency bands (uplink and downlink bands) can be used for the transmit and receive bands. Conversely, if the frequency band is used for Time Division Duplex (TDD), then the same frequency band can be used for both the transmit and receive bands.

[0042] The term "top view of the substrate" means observing an object by projecting it orthogonally onto the xy plane in the negative z-axis direction. The term "A overlaps with B in top view" means that the region of A projected orthogonally onto the xy plane overlaps with the region of B projected orthogonally onto the xy plane.

[0043] Furthermore, terms such as "parallel" and "perpendicular" indicating the relationship between elements, as well as terms such as "rectangle" indicating the shape of elements, and numerical ranges do not only mean strict, but also imply substantially equivalent ranges, for example, including a few percent degree of error.

[0044] (Implementation Method 1)

[0045] [1.1 Structure of surface acoustic wave resonator 1]

[0046] First, refer to Figure 1 as well as Figure 2 The overall structure of the surface acoustic wave resonator 1 according to Embodiment 1 will be described in detail. Figure 1 as well as Figure 2 These are a top view and a cross-sectional view of the surface acoustic wave resonator 1 according to this embodiment. Figure 2 The cross-section of surface acoustic wave resonator 1 in the diagram is... Figure 1 The cross section at line ii-ii.

[0047] in addition, Figure 1 as well as Figure 2 This is used to illustrate a typical structure of the surface acoustic wave resonator 1. The structure of the surface acoustic wave resonator 1 is not limited to... Figure 1 as well as Figure 2 Therefore, the following description of the surface acoustic wave resonator 1 should not be interpreted restrictively.

[0048] The surface acoustic wave resonator 1 includes a substrate 3, multiple electrodes 4, and a dielectric film 5. The substrate 3 includes a piezoelectric layer 31, a low-velocity layer 32, a high-velocity layer 33, and a support substrate 34.

[0049] The piezoelectric layer 31 is a piezoelectric layer stacked on the low-velocity acoustic layer 32, capable of propagating surface acoustic waves (SAW). Multiple electrodes 4 are disposed on the piezoelectric layer 31. The material of the piezoelectric layer 31 can be, for example, a piezoelectric single crystal or piezoelectric ceramic of lithium tantalate (LiTaO3), lithium niobate (LiNbO3), aluminum nitride, or zinc oxide. Furthermore, the multiple electrodes 4 can be disposed on one of the opposing main surfaces 31a and 31b of the piezoelectric layer 31, or on the other main surface 31b.

[0050] A low-velocity layer 32 is stacked on top of a high-velocity layer 33 and disposed between the piezoelectric layer 31 and the high-velocity layer 33. The sound speed of bulk waves propagating in the low-velocity layer 32 is lower than that of elastic waves such as surface waves and boundary waves propagating in the piezoelectric layer 31. The material of the low-velocity layer 32 can be, for example, a dielectric material such as silicon dioxide, glass, silicon oxynitride, lithium oxide, tantalum oxide, or a compound of silicon oxide with added fluorine, carbon, or boron, or any combination thereof. However, the material of the low-velocity layer 32 is not limited to these.

[0051] A high-velocity acoustic layer 33 is stacked on a support substrate 34 and disposed between a low-velocity acoustic layer 32 and the support substrate 34. The high-velocity acoustic layer 33 can confine the surface acoustic waves generated by the multiple electrodes 4 within the portion where the piezoelectric layer 31 and the low-velocity acoustic layer 32 are stacked, preventing leakage to layers lower than the high-velocity acoustic layer 33. The sound speed of the bulk waves propagating in the high-velocity acoustic layer 33 is higher than the sound speed of elastic waves such as surface waves and boundary waves propagating in the piezoelectric layer 31. The material of the high-velocity acoustic layer 33 can be, for example, piezoelectric materials such as silicon nitride, aluminum nitride, lithium tantalate, lithium niobate, and quartz; ceramics such as alumina, sapphire, magnesium oxide, silicon carbide, zirconium oxide, cordierite, mullite, block talc, and forsterite; dielectrics such as diamond and glass; semiconductors such as silicon and gallium nitride; resins; or any combination thereof. However, the material of the high-velocity acoustic layer 33 is not limited to these.

[0052] The support substrate 34 can support the piezoelectric layer 31, the low-velocity layer 32, and the high-velocity layer 33. The material of the support substrate 34 can be, for example, a piezoelectric material such as silicon nitride, aluminum nitride, lithium tantalate, lithium niobate, or quartz; a bauxite; sapphire; magnesium oxide; silicon nitride; silicon carbide; zirconium oxide; cordierite; mullite; block talc; magnesium olivine; ceramics such as diamond; dielectrics such as glass; semiconductors such as silicon or gallium nitride; or resin; or any combination thereof. However, the material of the support substrate 34 is not limited to these.

[0053] The hypersonic layer 33 and the support substrate 34 can also be combined into a single hypersonic support substrate. Materials used for the hypersonic support substrate include, for example, aluminum nitride, lithium tantalate, lithium niobate, piezoelectric materials such as quartz, bauxite, sapphire, magnesium oxide, silicon nitride, silicon carbide, zirconium oxide, cordierite, mullite, block talc, forsterite, spinel, ceramics such as silane, alumina, silicon oxynitride, DLC (diamond-like carbon), diamond, or semiconductors such as silicon, or any combination thereof. Furthermore, the aforementioned spinel types include aluminum compounds containing one or more elements selected from magnesium, iron, zinc, manganese, etc., and oxygen. Specific examples include spinel (MgAl2O4), iron spinel (FeAl2O4), zinc spinel (ZnAl2O4), and manganese spinel (MnAl2O4).

[0054] Multiple electrodes 4 are an example of at least one first electrode, disposed on substrate 3, including IDT (Interdigital Transducer) electrode 41 and a pair of reflective electrodes 42.

[0055] IDT electrode 41 is an example of the first IDT electrode, comprising two interleaved comb-shaped electrodes disposed on piezoelectric layer 31, capable of converting electrical signals into surface acoustic waves and performing inverse conversion. IDT electrode 41 includes multiple electrode fingers 411a and 411b and busbar electrodes 412a and 412b.

[0056] Multiple electrode fingers 411a and 411b are an example of multiple first electrode fingers, arranged alternately along the x-axis (first axis) and extending along the y-axis (second axis). One end of the multiple electrode fingers 411a is connected to the busbar electrode 412a and extends from the busbar electrode 412a in the negative direction of the y-axis. One end of the multiple electrode fingers 411b is connected to the busbar electrode 412b and extends from the busbar electrode 412b in the positive direction of the y-axis. Alternatively, the multiple electrode fingers 411a and 411b may not be arranged alternately one by one; for example, they may be arranged in two or more alternating positions.

[0057] Busbar electrode 412a extends along the x-axis and is connected to one end of a plurality of electrode fingers 411a. Busbar electrode 412a is arranged parallel to busbar electrode 412b and is separated from busbar electrode 412b in the positive direction of the y-axis.

[0058] Busbar electrode 412b extends along the x-axis and is connected to one end of a plurality of electrode fingers 411b. Busbar electrode 412b is arranged parallel to busbar electrode 412a and is separated from busbar electrode 412a in the negative y-axis direction.

[0059] A pair of reflective electrodes 42 is an example of a pair of first reflective electrodes, configured to sandwich the IDT electrode 41 in the x-axis direction in order to confine a given high-frequency signal resonating in the IDT electrode 41 within the IDT electrode 41. That is, the IDT electrode 41 is disposed between the pair of reflective electrodes 42 in the x-axis direction. Each pair of reflective electrodes 42 includes a plurality of electrode fingers 421 and busbar electrodes 422a and 422b. The plurality of electrode fingers 421 is an example of a plurality of first electrode fingers, arranged along the x-axis and extending respectively along the y-axis. The two ends of the plurality of electrode fingers 421 are connected to the busbar electrodes 422a and 422b. The busbar electrode 422a extends along the x-axis and is connected to one end of the plurality of electrode fingers 421. The busbar electrode 422b extends along the x-axis, is disposed parallel to the busbar electrode 422a, and is connected to the other end of the plurality of electrode fingers 421.

[0060] The materials used for the IDT electrode 41 and the pair of reflective electrodes 42 can be, for example, aluminum, titanium, gold, silver, copper, platinum, tungsten, molybdenum, ruthenium, or any combination thereof. However, the materials of the IDT electrode 41 and the pair of reflective electrodes 42 are not limited to these. Furthermore, the materials of the IDT electrode 41 and the pair of reflective electrodes 42 can be different from each other or the same.

[0061] A dielectric film 5 is disposed on a substrate 3, covering the substrate 3 and multiple electrodes 4. The dielectric film 5 includes multiple load members 51 and a protective film 52.

[0062] The plurality of load members 51 are an example of a plurality of first load members, and are made of dielectric. In this embodiment, the plurality of load members 51 are a plurality of load films (an example of a plurality of first load films) disposed separately on the substrate 3. Each of the plurality of load members 51, when viewed from above the substrate 3, at least partially overlaps with at least one corresponding electrode finger. Thus, the plurality of load members 51 can provide additional mass to several of the plurality of electrode fingers 411a, 411b, and 421.

[0063] As the material for the multiple load members 51, dielectric materials can be used. Specifically, tantalum pentoxide (Ta2O5), niobium pentoxide (Nb2O5), tungsten oxide (VI) (WO3), silicon nitride (SiN), titanium oxide (IV) (TiO2), cerium oxide (IV) (CeO2), hafnium oxide (IV) (HfO2), ytterbium oxide (III) (Yb2O3), silicon dioxide, bauxite, or any combination thereof can be used, and the method is not limited to these. By using a dielectric material with a higher density than the protective film 52, the multiple load members 51 can be made thinner. Furthermore, the multiple load members 51 can also be made of different materials.

[0064] A protective film 52 is disposed on the substrate 3, covering the IDT electrode 41, the reflective electrode 42, and the main surface 3a of the substrate 3. The protective film 52 can be made of a dielectric material; specifically, it can be silicon dioxide, silicon nitride, bauxite, or any combination thereof, and is not limited to these. Furthermore, the material of the protective film 52 can be different from or the same as the material of the load member 51. Additionally, the protective film 52 may not be included in the dielectric film 5, or it may be removed from the surface acoustic wave resonator 1.

[0065] The electrode finger region 3b on the main surface 3a of the substrate 3 is a region where multiple electrode fingers 411a, 411b, and 421 are disposed, and is equally divided into a first sub-region 3b1, a second sub-region 3b2, and a third sub-region 3b3 in the y-axis direction. The electrode finger region 3b is defined as a rectangular region that surrounds the multiple electrode fingers 411a, 411b, and 421 with the minimum area. Figure 1 In the diagram, the first sub-region 3b1, the second sub-region 3b2, and the third sub-region 3b3 are the left, central, and right portions of the electrode finger region 3b, respectively. The second sub-region 3b2 is located between the first sub-region 3b1 and the third sub-region 3b3.

[0066] Furthermore, the structure of the surface acoustic wave resonator 1 is not limited to Figure 1 as well as Figure 2 The structure can be varied. For example, the surface acoustic wave resonator 1 can also be a longitudinally coupled surface acoustic wave resonator. Furthermore, the substrate 3 of the surface acoustic wave resonator 1 may not include the low-velocity layer 32 and the high-velocity layer 33.

[0067] [1.2 Cross-sectional structure of electrode 411a and dielectric film 5]

[0068] Here, refer to Figure 3 as well as Figure 4 The cross-sectional structure of electrode finger 411a and dielectric film 5 will be described. Although electrode finger 411a will be described below, the other electrode fingers 411b and 421 are the same as electrode finger 411a, so their description will be omitted.

[0069] Figure 3 as well as Figure 4 This is a partial cross-sectional view of the surface acoustic wave resonator 1 according to this embodiment. Specifically, Figure 3 yes Figure 2 An enlarged view of part iii. Figure 4 yes Figure 2 An enlarged view of section iv.

[0070] in addition, Figure 3 as well as Figure 4This is used to illustrate the typical structure of electrode finger 411a and dielectric film 5. The structure of electrode finger 411a and dielectric film 5 is not limited to... Figure 3 as well as Figure 4 Therefore, the following descriptions of electrode 411a and dielectric film 5 should not be interpreted restrictively.

[0071] exist Figure 3 In this configuration, electrode finger 411a is covered by load member 51 and protective film 52. Specifically, a portion (right portion) of electrode finger 411a is covered by load member 51 and protective film 52, while the other portion (left portion) of electrode finger 411a is not covered by load member 51 but by protective film 52. Load member 51 is stacked on a portion of electrode finger 411a and piezoelectric layer 31, and protective film 52 is stacked on the other portion of electrode finger 411a, piezoelectric layer 31, and load member 51. Alternatively, load member 51 may be stacked on protective film 52.

[0072] The midpoint c51 of the load member 51 along the x-axis (width w51 of the load member 51) is offset by an offset amount s51 relative to the midpoint c411 of the electrode finger 411a along the x-axis (width w411 of the electrode finger 411a). That is, the load member 51 is offset along the x-axis towards the center of the IDT electrode 41 relative to the corresponding electrode finger 411a.

[0073] Furthermore, the thickness t51a of the load member 51 on the top surface of the electrode finger 411a is greater than the thickness t51b of the load member 51 on the side surface of the electrode finger 411a, and is also greater than the thickness t52 of the protective film 52. Additionally, in the following description, when referring only to the thickness of the load member on the electrode finger, it refers to the thickness of the load member on the top surface of the electrode finger (in...). Figure 3 The thickness is t51a.

[0074] exist Figure 4 In this configuration, electrode 411a is not covered by the load member 51 but by the protective film 52. Therefore, Figure 4 The thickness t5 (=t52) of the dielectric film 5 on electrode 411a is greater than that of electrode 411a. Figure 3 The thickness t5 (=t51a+t52) of the dielectric film 5 on electrode 411a is small.

[0075] Furthermore, the thicknesses of the dielectric film 5, the load member 51 (load film), and the protective film 52 can be determined by observing the cross-section of the surface acoustic wave resonator 1 using a scanning electron microscope (SEM). Here, the cross-section of the surface acoustic wave resonator 1 is a cross-section perpendicular to the main surface 3a of the substrate 3, and is a cross-section through a straight line connecting the center points of the intersection widths of the plurality of electrode fingers 411a, 411b, and 421. The intersection width of the plurality of electrode fingers 411a, 411b, and 421 is the length of the area where adjacent electrode fingers intersect in the direction perpendicular to the propagation direction (y-axis direction) when observed in the propagation direction (x-axis direction) of the surface acoustic wave.

[0076] [1.3 The locations of multiple electrodes 411a, 411b, and 421 and multiple load members 51]

[0077] Next, refer to Figure 5 The positional relationship between the multiple electrode fingers 411a, 411b and 421 and the multiple load members 51 as viewed from above on the substrate 3 is explained.

[0078] Figure 5 This is a top view of the plurality of electrodes 4 and the plurality of load members 51 involved in this embodiment. Specifically, Figure 5 It is a diagram in which multiple electrodes 4 and multiple load components 51 are projected onto the xy plane.

[0079] in addition, Figure 5 This is used to illustrate a typical positional relationship between the multiple electrodes 4 and the multiple load members 51. The positional relationship between the multiple electrodes 4 and the multiple load members 51 is not limited to... Figure 5 The positional relationship. Therefore, the following description of the multiple electrodes 4 and multiple load members 51 should not be interpreted restrictively.

[0080] Multiple load members 51 correspond one-to-one with several of the multiple electrode fingers 411a, 411b, and 421. Each load member 51 has a shape similar to (rectangular shape) of its corresponding electrode finger 411a, 411b, or 421 and extends along the y-axis. Each load member 51 partially overlaps with its corresponding electrode finger 411a, 411b, or 421 when viewed from above the substrate 3. Specifically, a portion of each load member 51 overlaps with a portion of its corresponding electrode finger 411a, 411b, or 421, and other portions of each load member 51 overlap with a portion of the gap between its corresponding electrode finger 411a, 411b, or 421 and adjacent electrode fingers 411a, 411b, or 421. Alternatively, each load member 51 may overlap entirely with its corresponding electrode finger 411a, 411b, or 421 when viewed from above the substrate 3, rather than partially. Figure 5 In the top view of the substrate 3, the area of ​​the overlapping portion of each of the multiple load members 51 and the corresponding electrode finger 411a, 411b or 421 is approximately half the total area of ​​each of the multiple load members 51, but is not limited to this.

[0081] Each of the multiple load members 51 is offset relative to a corresponding electrode finger 411a, 411b, or 421 along the x-axis towards the center of the IDT electrode 41. For example, as Figure 3 As shown, the midpoint c51 of the load member 51 along the x-axis (the width w51 of the load member 51) is offset from the midpoint c411 of the electrode finger 411a along the x-axis (the width w411 of the electrode finger 411a) in the center direction (positive direction of the x-axis) of the IDT electrode 41.

[0082] In a top view of the substrate 3, multiple load members 51 partially overlap with several of the multiple electrode fingers 411a and 411b of the IDT electrode 41, and also partially overlap with several of the multiple electrode fingers 421 of each pair of reflective electrodes 42. Specifically, the multiple load members 51 partially overlap with two electrode fingers 411a and 411b of the IDT electrode 41 that are closer to the pair of reflective electrodes 42. Furthermore, the multiple load members 51 partially overlap with two electrode fingers 421 of each pair of reflective electrodes 42 that are closer to the IDT electrode 41.

[0083] The number of electrode fingers overlapping with multiple load members 51 in the electrode fingers 411a, 411b and 421 disposed in the first sub-region 3b1 (in Figure 5The number of electrode fingers overlapping with multiple load members 51 in the electrode fingers 411a and 411b arranged in the second sub-region 3b2 (4 in the middle) is greater than the number of electrode fingers in the second sub-region 3b2 (4 in the middle). Figure 5 (0 in the middle) More. Similarly, the number of electrode fingers overlapping with multiple load members 51 in the electrode fingers 411a, 411b and 421 arranged in the third sub-region 3b3 (in Figure 5 The number of electrode fingers overlapping with multiple load members 51 in the electrode fingers 411a and 411b arranged in the second sub-region 3b2 (4 in the middle) is greater than the number of electrode fingers in the second sub-region 3b2 (4 in the middle). Figure 5 (0 roots in the middle) More.

[0084] Furthermore, the number of electrode fingers disposed in the first sub-region 3b1 that overlap with multiple load members 51 (in Figure 5 (There are 4 in the middle) relative to the total number of electrode fingers 411a, 411b and 421 (in Figure 5 The value of the ratio of the 7 roots in the middle (in Figure 5 The number of electrode fingers (4 / 7) is greater than the number of electrode fingers that overlap with multiple load members 51 in the second sub-region 3b2 (in Figure 5 The number of electrodes (0 in the middle) is relative to the total number of electrodes 411a and 411b (in the middle). Figure 5 The value of the ratio of the 7 roots in the middle (in Figure 5 (0 / 7 in the middle). Similarly, the number of electrode fingers arranged in the third sub-region 3b3 that overlap with multiple load members 51 (in Figure 5 (There are 4 in the middle) relative to the total number of electrode fingers 411a, 411b and 421 (in Figure 5 The value of the ratio of the 7 roots in the middle (in Figure 5 The number of electrode fingers (4 / 7) is greater than the number of electrode fingers that overlap with multiple load members 51 in the second sub-region 3b2 (in Figure 5 The number of electrodes (0 in the middle) is relative to the total number of electrodes 411a and 411b (in the middle). Figure 5 The value of the ratio of the 7 roots in the middle (in Figure 5 The value is 0 / 7.

[0085] At this point, the electrode fingers configured across the two sub-regions are counted as electrode fingers configured in each of the two sub-regions. For example, in Figure 5 In this process, the electrode fingers 411a disposed at the boundary between the first sub-region 3b1 and the second sub-region 3b2 are counted as electrode fingers disposed in the first sub-region 3b1, and further counted as electrode fingers disposed in the second sub-region 3b2.

[0086] Furthermore, the number and arrangement of electrode fingers overlapping with multiple load members 51 are not limited to Figure 5For example, the multiple load members 51 may also overlap with the electrode fingers 411a and / or 411b disposed in the second sub-region 3b2. As another example, the multiple load members 51 may also overlap entirely with the multiple electrode fingers 421 of a pair of reflective electrodes 42. As yet another example, the multiple load members 51 may also partially overlap with one or more of the multiple electrode fingers 421 of each pair of reflective electrodes 42 that are further away from the IDT electrode 41.

[0087] The multiple electrode fingers 411a, 411b, and 421 configured in the first sub-region 3b1 and the third sub-region 3b3 respectively do not overlap with a single load member 51, but rather overlap with two or more load members 51. Figure 5 In this configuration, four electrode fingers 411a, 411b, and 421 disposed in the first sub-region 3b1 and the third sub-region 3b3 respectively overlap with four load members 51. That is, the plurality of load members 51 includes two or more load members 51 that overlap with two or more electrode fingers disposed in the first sub-region 3b1 and two or more load members 51 that overlap with two or more electrode fingers disposed in the third sub-region 3b3.

[0088] Furthermore, the number, shape, and dimensions (length along the x-axis, length along the y-axis, and thickness) of the multiple load members 51 can be determined according to the required specifications of the surface acoustic wave resonator 1. In addition, the number, shape, dimensions, spacing, and duty cycle of the multiple electrode fingers 411a, 411b, and 421 can also be determined according to the required specifications of the surface acoustic wave resonator 1.

[0089] For example, the duty cycles of the multiple electrode fingers 411a, 411b, and 421 may be non-uniform within the surface acoustic wave resonator 1. For instance, the duty cycle (w1 / p1) of the multiple electrode fingers 411a, 411b, and 421 that overlap with the multiple load members 51 may differ from the duty cycle (w2 / p2) of the multiple electrode fingers 411a and 411b that do not overlap with the multiple load members 51. Furthermore, the duty cycle of the multiple electrode fingers is defined as the ratio of the average (average width) of the lengths of the multiple electrode fingers along the x-axis to the average spacing between the multiple electrode fingers.

[0090] For example, the spacing of the multiple electrode fingers 411a, 411b, and 421 can also be non-uniform within the surface acoustic wave resonator 1. For instance, the spacing p3 between electrode fingers overlapping with the load member 51 and those not overlapping with it can differ from the spacing p1 between the electrode fingers overlapping with the load member 51, and also from the spacing p2 between the electrode fingers not overlapping with it. That is, the interval (spacing p3) between an electrode finger overlapping any one of the load members 51 and an electrode finger adjacent to that finger that does not overlap with any of the load members 51 can differ from the interval (spacing p1) between two adjacent electrode fingers overlapping with the load members 51, and also from the interval (spacing p2) between two adjacent electrode fingers not overlapping with any of the load members 51. The interval between two electrode fingers is defined by the length of a line segment on a straight line parallel to the x-axis, connecting the midpoint of the length of one of the two electrode fingers along the x-axis to the midpoint of the length of the other electrode finger along the x-axis.

[0091] For example, the duty cycles of the plurality of electrode fingers 411a and 411b that do not overlap with the plurality of load members 51 may also be non-uniform within the surface acoustic wave resonator 1. For example, the width w2 of at least one of the plurality of electrode fingers 411a and 411b that do not overlap with the plurality of load members 51 may also be different from the width w2 of at least one of the other plurality of electrode fingers 411a and 411b that do not overlap with the plurality of load members 51. For example, the spacing (p2) of at least one group of adjacent electrode fingers among the plurality of electrode fingers 411a and 411b that do not overlap with the plurality of load members 51 may also be different from the spacing (p2) of the other at least one group of adjacent electrode fingers among the plurality of electrode fingers 411a and 411b that do not overlap with the plurality of load members 51. Furthermore, the spacing (p2) of adjacent electrode fingers in multiple groups of the plurality of electrode fingers 411a and 411b that do not overlap with the plurality of load members 51 may also be different from each other. At this time, the spacing (p2) of adjacent electrode fingers in all groups of multiple electrode fingers 411a and 411b that do not overlap with multiple load members 51 can also be different from each other.

[0092] [1.4 Comparison of the characteristics of surface acoustic wave resonators between Examples 1 and 2 and Comparative Examples 1 to 4]

[0093] Reference Figures 6-9 A comparison of the characteristics of the surface acoustic wave resonators according to Embodiment 1 and Embodiment 2 based on Embodiment 1 and the surface acoustic wave resonators according to Comparative Examples 1 to 4 will be described.

[0094] Furthermore, the specifications of the surface acoustic wave resonator involved in Example 1 are as follows (a) to (h). (a) The support substrate 34 is a silicon substrate with a plane orientation of

[111] . (b) The high-velocity layer 33 is a silicon nitride (SiN) layer with a thickness of 300 nm. (c) The low-velocity layer 32 is a silicon dioxide (SiO2) layer with a thickness of 673 nm. (d) The piezoelectric layer 31 is a lithium tantalate (LiTaO3) layer with a thickness of 1000 nm and a cut angle of 35 degrees. (e) The IDT electrode 41 has a three-layer structure, which is a titanium (Ti) layer with a thickness of 60 nm, a copper-aluminum alloy (Al-1%Cu) layer with a thickness of 380 nm, and a titanium (Ti) layer with a thickness of 4 nm. The spacing of the IDT electrodes 41 is 2.5 μm, and the duty cycle of the IDT electrodes 41 is 0.435. (f) The IDT electrode 41 has 81 electrode fingers 411a and 411b respectively. (g) Each of the pair of reflective electrodes 42 has 10 electrode fingers 421. (h) The load member 51 is a tantalum pentoxide (Ta2O5) film with a thickness of 120 nm. The load member 51 covers the electrode fingers 421 of each of the pair of reflective electrodes 42, and covers the 5 electrode fingers 411a and 411b of the IDT electrode 41 that are closer to each of the pair of reflective electrodes 42. (h) The protective film 52 is a silicon dioxide (SiO2) film with a thickness of 50 nm.

[0095] Furthermore, compared to the surface acoustic wave resonator of Example 1, the specifications of the surface acoustic wave resonator in Example 2 are the same in (a) to (e) and (h), while (f) and (g) are replaced by (f') and (g'). (f') does not include a pair of reflective electrodes 42. (g') The load member 51 is a tantalum pentoxide (Ta2O5) film with a thickness of 120 nm. The load member 51 covers 10 electrode fingers 411a and 411b of the IDT electrode 41, which are located near both ends in the propagation direction (x-axis direction).

[0096] Figure 6 This is a graph showing the frequency characteristics of the Q-values ​​of the surface acoustic wave resonators involved in Embodiment 1 and Comparative Example 1. Figure 6 In the diagram, the horizontal axis represents frequency, and the vertical axis represents Q value.

[0097] The surface acoustic wave resonator of Comparative Example 1 was obtained by removing the load member 51 from the surface acoustic wave resonator of Example 1. That is, the dielectric film 5 of the surface acoustic wave resonator of Comparative Example 1 only includes the protective film 52 and does not include the load member 51.

[0098] like Figure 6As shown, the Q value of the surface acoustic wave resonator according to Example 1 is higher than that of the surface acoustic wave resonator according to Comparative Example 1. In particular, the Q value is improved in the frequency range of 700-800MHz.

[0099] Figure 7 This is a graph showing the resonant characteristics of the surface acoustic wave resonators involved in Embodiment 1 and Comparative Example 2. Figure 7 In the diagram, the horizontal axis represents frequency, and the vertical axis represents phase.

[0100] Comparative Example 2 relates to a surface acoustic wave resonator by adjusting the offset of the load member 51 and the corresponding electrode fingers 411a, 411b or 421 in the surface acoustic wave resonator of Example 1. Figure 3 The offset s51 is set to 0. That is, in the surface acoustic wave resonator involved in Comparative Example 2, the x-coordinate of the center of the load member 51 along the x-axis coincides with the x-coordinate of the center of the corresponding electrode finger 411a, 411b or 421 along the x-axis.

[0101] like Figure 7 As shown, in the frequency range of 720-760MHz in which the longitudinal mode is generated, the surface acoustic wave resonator according to Example 1 is able to suppress phase variations (refer to the area enclosed by the dashed line) compared to the surface acoustic wave resonator according to Comparative Example 2. That is, the surface acoustic wave resonator according to Example 1 is able to suppress the longitudinal mode and suppress the ripple caused by the longitudinal mode compared to the surface acoustic wave resonator according to Comparative Example 2.

[0102] Figure 8 This is a graph showing the resonant characteristics of the surface acoustic wave resonators involved in Embodiment 1 and Comparative Example 3. Figure 8 In the diagram, the horizontal axis represents frequency, and the vertical axis represents attenuation.

[0103] The surface acoustic wave resonator of Comparative Example 3 is obtained by removing the load member 51 that overlaps with the plurality of electrode fingers 411a and 411b of the IDT electrode 41 from the surface acoustic wave resonator of Example 1. That is, the plurality of load members 51 of the surface acoustic wave resonator of Comparative Example 3 overlap only with the plurality of electrode fingers 421 of the reflective electrode 42 among the plurality of electrode fingers 411a, 411b and 421 of the IDT electrode 41 and the reflective electrode 42.

[0104] like Figure 8 As shown, in the frequency range of 840-880MHz where stopband ripple is generated, the surface acoustic wave resonator according to Example 1 is able to suppress attenuation variations (refer to the area enclosed by the dashed line) compared to the surface acoustic wave resonator according to Comparative Example 3. In other words, the surface acoustic wave resonator according to Example 1 is able to suppress stopband ripple compared to the surface acoustic wave resonator according to Comparative Example 3.

[0105] Figure 9 This is a graph showing the frequency characteristics of the Q-values ​​of the surface acoustic wave resonators involved in Example 2 and Comparative Example 4. Figure 9 In the diagram, the horizontal axis represents frequency, and the vertical axis represents Q value.

[0106] The surface acoustic wave resonator involved in Comparative Example 4 reduces the thickness of the load member 51 on the side of the electrode fingers (e.g., in the surface acoustic wave resonator involved in Example 2) by adjusting the thickness of the load member 51 on the side of the electrode fingers. Figure 3 The thickness t51b) and the thickness of the load member 51 on the top surface (e.g., Figure 3 The thickness t51a) is equal to that of the surface acoustic wave resonator. That is, the multiple load members 51 of the surface acoustic wave resonator involved in Comparative Example 4 cover the top and side surfaces of the 20 electrode fingers 411a and 411b of the IDT electrode 41 with approximately the same thickness.

[0107] like Figure 9 As shown, the Q value of the surface acoustic wave resonator according to Example 2 is improved compared to the surface acoustic wave resonator according to Comparative Example 4. In particular, the Q value in the frequency range of 800-840MHz is improved.

[0108] [1.5 Summary]

[0109] As described above, the surface acoustic wave resonator 1 according to this embodiment includes: a substrate 3 containing a piezoelectric layer 31; at least one electrode 4 disposed on the substrate 3, including an IDT electrode 41; and a plurality of load members 51 disposed separately on or within the substrate 3, and made of dielectric. The at least one electrode 4 includes a plurality of electrode fingers 411a, 411b, and 421 arranged along the x-axis and extending along a y-axis perpendicular to the x-axis on the substrate 3. Each of the plurality of load members 51, when viewed from above the substrate 3, at least partially overlaps with the corresponding at least one electrode finger. The number of electrode fingers overlapping with the plurality of load members 51 among the electrode fingers disposed in the first sub-region 3b1 and the number of electrode fingers disposed in the third sub-region 3b3 are... The number of electrode fingers overlapping with multiple load members 51 in the first sub-region 3b1 is greater than the number of electrode fingers overlapping with multiple load members 51 in the electrode fingers disposed in the second sub-region 3b2. The first sub-region 3b1, the second sub-region 3b2 and the third sub-region 3b3 are obtained by equally dividing the electrode finger region 3b on the substrate 3, which is disposed with multiple electrode fingers 411a, 411b and 421, in the y-axis direction. The second sub-region 3b2 is located between the first sub-region 3b1 and the third sub-region 3b3. The multiple load members 51 include two or more load members 51 that overlap with the electrode fingers disposed in the first sub-region 3b1 and two or more load members 51 that overlap with the electrode fingers disposed in the third sub-region 3b3.

[0110] Therefore, by adding mass to the multiple electrode fingers 411a, 411b, and 421 arranged in the first sub-region 3b1 and the third sub-region 3b3 using multiple load members 51, the reflectivity can be increased, thereby improving the effect of confining surface acoustic waves into the surface acoustic wave resonator 1. As a result, as... Figure 6 As shown, the Q value of the surface acoustic wave resonator 1 can be improved. Furthermore, since the multiple load members 51 are made of dielectric, it becomes easier to ensure the distance between adjacent electrode fingers compared to the case where the multiple load members 51 are made of conductor, thus suppressing a decrease in power withstand capability.

[0111] For example, in the surface acoustic wave resonator 1 of this embodiment, at least one electrode 4 may also include a pair of reflective electrodes 42, and the IDT electrode 41 may also be disposed between the pair of reflective electrodes 42.

[0112] Therefore, by means of a pair of reflective electrodes 42, the effect of sealing the surface acoustic wave into the surface acoustic wave resonator 1 can be further improved, and the Q value of the surface acoustic wave resonator 1 can be further improved.

[0113] For example, in the surface acoustic wave resonator 1 of this embodiment, at least one of the plurality of load members 51 may at least partially overlap with at least one corresponding electrode finger of the IDT electrode 41 when viewed from above the substrate 3, and at least one of the other plurality of load members 51 may at least partially overlap with at least one corresponding electrode finger of the reflective electrode 42 when viewed from above the substrate 3.

[0114] Therefore, the electrode fingers 411a, 411b, and 421 of the multiple load members 51 overlap with both the IDT electrode 41 and the reflective electrode 42, thus... Figure 8 As shown, compared to the case where multiple load members 51 overlap only with the electrode fingers 421 of the reflective electrode 42, stopband ripple can be suppressed.

[0115] For example, in the surface acoustic wave resonator 1 of this embodiment, the multiple load members 51 may also correspond one-to-one with several of the multiple electrode fingers 411a, 411b and 421.

[0116] Therefore, the positional relationship (e.g., the area of ​​the overlapping portion) of the multiple load members 51 and multiple electrode fingers 411a, 411b or 421 can be adjusted more precisely, which can improve the characteristics of the surface acoustic wave resonator 1.

[0117] For example, in the surface acoustic wave resonator 1 of this embodiment, each of the plurality of load members 51 may overlap with a portion of a corresponding electrode finger when viewed from above the substrate 3.

[0118] Thus, multiple load members 51 can overlap with a portion of their corresponding electrode fingers, thereby suppressing the longitudinal mode and inhibiting ripples caused by the longitudinal mode.

[0119] For example, in the surface acoustic wave resonator 1 of this embodiment, the midpoint of the length of each of the plurality of load members 51 along the x-axis can also be offset along the x-axis towards the center of the IDT electrode 41 relative to the midpoint of the length of the corresponding electrode along the x-axis.

[0120] Therefore, each of the multiple load members 51 can be offset relative to the center side of the corresponding electrode pointing to the IDT electrode 41, thus... Figure 7 As shown, it can suppress the longitudinal mode and thus suppress the ripple caused by the longitudinal mode.

[0121] For example, in the surface acoustic wave resonator 1 of this embodiment, the plurality of load members 51 may also be a plurality of load films disposed on the substrate 3, and the plurality of load films may at least partially cover several of the plurality of electrode fingers 411a, 411b and 421.

[0122] Therefore, multiple load films disposed on the substrate 3 can be used as multiple load members 51, and the surface acoustic wave resonator 1 can be manufactured more simply compared to the case where multiple load members 51 are disposed in the substrate 3.

[0123] For example, in the surface acoustic wave resonator 1 of this embodiment, the thickness of the load member 51 on the top surface of the corresponding electrode finger is greater than the thickness of the load member 51 on the side surface of the corresponding electrode finger in each of the plurality of load members 51.

[0124] Therefore, as Figure 9 As shown, it can improve the Q value of surface acoustic wave resonator 1.

[0125] For example, the surface acoustic wave resonator 1 according to this embodiment may also include a protective film 52, which is disposed on the substrate 3 and covers the substrate 3 and at least a portion of the plurality of electrode fingers 411a, 411b and 421.

[0126] Therefore, multiple load members 51 (multiple load films) and a protective film 52 can be disposed on the substrate 3. In addition to the improvement of the Q value of the surface acoustic wave resonator 1 by the multiple load members 51, it is also possible to improve the characteristics (e.g., temperature characteristics) of the surface acoustic wave resonator 1 by the protective film 52.

[0127] For example, in the surface acoustic wave resonator 1 of this embodiment, the protective film 52 may also be stacked on multiple load members 51.

[0128] Therefore, a protective film 52 is stacked on multiple load members 51 (multiple load films). Even with this configuration, the Q value of the surface acoustic wave resonator 1 can be improved.

[0129] For example, in the surface acoustic wave resonator 1 of this embodiment, the plurality of load members 51 may also be made of a different material than the protective film 52.

[0130] Therefore, by using materials suitable for the multiple load members 51 and the protective film 52 respectively, it is possible to simplify the manufacturing of the surface acoustic wave resonator 1 or further improve the Q value.

[0131] For example, in the surface acoustic wave resonator 1 of this embodiment, the plurality of load members 51 may also include tantalum pentoxide, niobium pentoxide, tungsten oxide (VI), silicon nitride, titanium oxide (IV), cerium oxide (IV), hafnium oxide (IV), or ytterbium oxide (III), and the protective film 52 may also include silicon dioxide or silicon nitride.

[0132] Therefore, a material with a higher density than the protective film 52 can be used as the material for the multiple load members 51, thus making the multiple load members 51 thinner and simplifying the manufacturing of the surface acoustic wave resonator 1.

[0133] For example, in the surface acoustic wave resonator 1 of this embodiment, the spacing between the electrode finger that overlaps with the plurality of load members 51 and the electrode finger that is adjacent to the electrode finger but does not overlap with the plurality of load members 51 may be different from the spacing between two adjacent electrode fingers that overlap with the plurality of load members 51 or the spacing between two adjacent electrode fingers that do not overlap with the plurality of load members 51.

[0134] Therefore, it is possible to suppress the longitudinal mode and inhibit the ripples caused by the longitudinal mode.

[0135] For example, in the surface acoustic wave resonator 1 of this embodiment, the duty cycle of two or more electrode fingers that overlap with the plurality of load members 51 may be different from the duty cycle of two or more electrode fingers that do not overlap with any of the plurality of load members 51.

[0136] Therefore, the duty cycle of multiple electrode fingers can be set according to their relationship with the load member 51, and the Q value can be further improved.

[0137] For example, in the surface acoustic wave resonator 1 of this embodiment, the spacing of two or more electrode fingers 411a, 411b and 421 that overlap with the plurality of load members 51 may be different from the spacing of two or more electrode fingers 411a, 411b and 421 that do not overlap with any of the plurality of load members 51.

[0138] Therefore, the spacing of multiple electrode fingers can be set according to their relationship with the load member 51, and the Q value can be further improved.

[0139] For example, in the surface acoustic wave resonator 1 of this embodiment, the width of at least one of two or more electrode fingers 411a, 411b and 421 that do not overlap with any of the plurality of load members 51 may be different from the width of at least one of the other two or more electrode fingers 411a, 411b and 421 that do not overlap with any of the plurality of load members 51.

[0140] Therefore, the width of two or more electrode fingers that do not overlap with any of the multiple load members 51 can be set individually, and further improvement of the Q value can be sought.

[0141] For example, in the surface acoustic wave resonator 1 of this embodiment, the spacing of at least one group of adjacent electrode fingers among two or more electrode fingers 411a, 411b and 421 that do not overlap with any of the plurality of load members 51 may be different from the spacing of at least another group of adjacent electrode fingers among two or more electrode fingers 411a, 411b and 421 that do not overlap with any of the plurality of load members 51.

[0142] Therefore, the spacing between adjacent electrode fingers among two or more electrode fingers that do not overlap with any of the multiple load members 51 can be set individually, and further improvement of the Q value can be sought.

[0143] For example, in the surface acoustic wave resonator 1 of this embodiment, the spacing between adjacent electrode fingers of multiple groups of two or more electrode fingers 411a, 411b and 421 that do not overlap with any of the multiple load members 51 may also be different from each other.

[0144] Therefore, the spacing between adjacent electrode fingers among two or more electrode fingers that do not overlap with any of the multiple load members 51 can be set individually, and further improvement of the Q value can be sought.

[0145] Furthermore, the surface acoustic wave resonator 1 according to this embodiment includes: a substrate 3, including a piezoelectric layer 31; at least one electrode 4 disposed on the substrate 3, including an IDT electrode 41; and a dielectric film 5 disposed on the at least one electrode 4. The at least one electrode 4 includes a plurality of electrode fingers 411a, 411b, and 421 arranged along the x-axis and extending along the y-axis perpendicular to the x-axis on the substrate 3. The average thickness of the dielectric film 5 disposed on the electrode fingers of the first sub-region 3b1 and the average thickness of the dielectric film 5 disposed on the electrode fingers of the third sub-region 3b3 are both greater than the average thickness of the dielectric film 5 disposed on the electrode fingers of the second sub-region 3b2. The first sub-region 3b1, the second sub-region 3b2, and the third sub-region 3b3 are obtained by equally dividing the electrode finger region 3b on the substrate 3, which is disposed with a plurality of electrode fingers 411a, 411b, and 421, in the y-axis direction. The second sub-region 3b2 is located between the first sub-region 3b1 and the third sub-region 3b3.

[0146] Therefore, a thicker dielectric film 5 can be used to add mass to the multiple electrode fingers 411a, 411b, and 421 disposed in the first sub-region 3b1 and the third sub-region 3b3. This improves reflectivity and enhances the effect of containing surface acoustic waves within the surface acoustic wave resonator 1. As a result, as... Figure 6 As shown, the Q value of the surface acoustic wave resonator 1 can be improved. Furthermore, since mass can be added using a dielectric, it becomes easier to ensure the distance between adjacent electrode fingers compared to adding mass using a conductor, thus suppressing the decrease in power tolerance.

[0147] (Modification 1 of Implementation Method 1)

[0148] Next, a variation of Embodiment 1 will be described. The main difference between this variation and Embodiment 1 is that multiple load members 51A are disposed within the substrate 3 instead of multiple load members 51. Hereinafter, this variation will be described focusing on the differences from Embodiment 1. Figure 10 Please provide an explanation.

[0149] Figure 10 This is a cross-sectional view of the surface acoustic wave resonator 1 involved in this modified example. Additionally, Figure 10 This is used to illustrate a typical structure of the surface acoustic wave resonator 1. The structure of the surface acoustic wave resonator 1 is not limited to... Figure 10 Therefore, the following description of the surface acoustic wave resonator 1 should not be interpreted restrictively.

[0150] The surface acoustic wave resonator 1 includes a substrate 3, multiple electrodes 4, a dielectric film 5A, and a load member 51A.

[0151] A dielectric film 5A is disposed on the substrate 3, covering the substrate 3 and multiple electrodes 4. The dielectric film 5A includes a protective film 52 but does not include multiple load members. Alternatively, in this modified example, the surface acoustic wave resonator 1 may not have the dielectric film 5A.

[0152] The plurality of load members 51A is an example of a plurality of first load members, which are made of dielectric. In this modified example, the plurality of load members 51A are disposed separately within the substrate. Each of the plurality of load members 51A, when viewed from above the substrate 3, at least partially overlaps with at least one corresponding electrode finger. Thus, the plurality of load members 51A can provide additional mass to several of the plurality of electrode fingers 411a, 411b, and 421.

[0153] As the material for the multiple load members 51A, a material with a higher density than the low-velocity layer 32 can be used. Specifically, tantalum pentoxide (Ta2O5), silicon dioxide, silicon nitride, bauxite, or any combination thereof can be used, but are not limited to these.

[0154] Alternatively, multiple load members 51A may be disposed in a layer different from the low-velocity layer 32 within the substrate 3. For example, multiple load members 51A may also be disposed within the piezoelectric layer 31, the high-velocity layer 33, or the support substrate 34.

[0155] As described above, in the surface acoustic wave resonator 1 of this modified example, multiple load members 51A can also be arranged within the substrate 3.

[0156] Therefore, the multiple load members 51A do not contact the multiple electrode fingers 411a, 411b and 421, thus suppressing the variation of the characteristics of the surface acoustic wave resonator 1 and improving the Q value.

[0157] For example, in the surface acoustic wave resonator 1 of this modified example, the substrate 3 may also include a low-velocity layer 32 in which the sound velocity of the propagating bulk wave is lower than the sound velocity of the elastic wave propagating in the piezoelectric layer 31. The piezoelectric layer 31 may also be disposed on the low-velocity layer 32, and a plurality of load members 51A may also be disposed in the low-velocity layer 32.

[0158] Therefore, multiple load members 51A can be configured within the low-sound-velocity layer 32, and the Q value can be improved even under such conditions.

[0159] (Modification 2 of Implementation Method 1)

[0160] Next, a variation of Embodiment 1, Example 2, will be described. The main difference between this variation and Embodiment 1 is that a load member 51 overlaps with multiple electrode fingers. Hereinafter, this variation will be described focusing on the differences from Embodiment 1, referring to… Figure 11 Please provide an explanation.

[0161] Figure 11 This is a top view of the multiple electrodes 4 and multiple load members 51B involved in this modified example. Specifically, Figure 11 It is a diagram in which multiple electrodes 4 and multiple load components 51B are projected onto the xy plane.

[0162] in addition, Figure 11 This is used to illustrate a typical positional relationship between the multiple electrodes 4 and the multiple load members 51B. The positional relationship between the multiple electrodes 4 and the multiple load members 51B is not limited to... Figure 11 The positional relationship. Therefore, the following description of the multiple electrodes 4 and multiple load members 51B should not be interpreted restrictively.

[0163] The plurality of load members 51B is an example of a plurality of first load members, and is made of dielectric. In this modified example, the plurality of load members 51B are also, like the plurality of load members 51 in Embodiment 1, a plurality of load films (an example of a plurality of first load films) disposed separately on the substrate 3. Each of the plurality of load members 51B, when viewed from above the substrate 3, at least partially overlaps with at least two corresponding electrode fingers. Thus, the plurality of load members 51B can provide additional mass to several of the plurality of electrode fingers 411a, 411b, and 421. The same material as the plurality of load members 51B in Embodiment 1 can be used as the material for the plurality of load members 51B.

[0164] In this modified example, each of the plurality of load members 51B, viewed from above on the substrate 3, at least partially overlaps with the corresponding two electrode fingers 411a and 411b or 421. Figure 11 In the substrate 3, each of the two load members 51B, viewed from above, at least partially overlaps with its corresponding two electrode fingers 411a and 411b. Furthermore, each of the other two or more load members 51B at least partially overlaps with its corresponding two electrode fingers 421.

[0165] As described above, in the surface acoustic wave resonator 1 of this modified example, each of the plurality of load members 51B can at least partially overlap with the corresponding plurality of electrode fingers when viewed from above the substrate 3.

[0166] Even in this case, the Q value of the surface acoustic wave resonator 1 can be improved in the same way as in embodiment 1.

[0167] (Modification 3 of Implementation Method 1)

[0168] Next, a variation of Embodiment 1, Example 3, will be described. The main difference between this variation and Embodiment 1 is that the surface acoustic wave resonator does not include a pair of reflecting electrodes. Hereinafter, this variation will be described focusing on its differences from Embodiment 1, referring to… Figure 12Please provide an explanation.

[0169] Figure 12 This is a top view of the electrode 4C and multiple load members 51C involved in this modified example. Specifically, Figure 12 It is a diagram in which electrode 4C and multiple load components 51C are projected orthogonally onto the xy plane.

[0170] in addition, Figure 12 This is used to illustrate the typical positional relationship of electrode 4C and multiple load members 51C. The positional relationship of electrode 4C and multiple load members 51C is not limited to... Figure 12 The positional relationship. Therefore, the following description of the electrode 4C and the multiple load members 51C should not be interpreted restrictively.

[0171] Electrode 4C includes an IDT electrode 41 disposed on substrate 3. Additionally, in this modified example, electrode 4C does not include a pair of reflective electrodes 42.

[0172] The plurality of load members 51C is an example of a plurality of first load members, and is made of dielectric. In this modified example, the plurality of load members 51C are also, like the plurality of load members 51 in Embodiment 1, a plurality of load films (an example of a plurality of first load films) disposed separately on the substrate 3. Each of the plurality of load members 51C, when viewed from above the substrate 3, at least partially overlaps with at least one corresponding electrode finger. Thus, the plurality of load members 51C can provide additional mass to several of the plurality of electrode fingers 411a and 411b. The same material as the plurality of load members 51C in Embodiment 1 can be used as the material for the plurality of load members 51.

[0173] As described above, in the surface acoustic wave resonator 1 involved in this modified example, electrode 4C may also not include reflective electrode 42.

[0174] Even under such circumstances, the surface acoustic wave resonator 1 is able to improve the Q value in the same way as in embodiment 1.

[0175] (Modification 4 of Implementation Method 1)

[0176] Next, a variation of Embodiment 1, 4, will be described. The main difference between this variation and Embodiment 1 is that the front ends of the electrode fingers 411a and 411b of the IDT electrode 41 overlap with other load members. Hereinafter, this variation will be described focusing on the differences from Embodiment 1, referring to… Figure 13 as well as Figure 14 Please provide an explanation.

[0177] Figure 13 This is a top view of the multiple electrodes 4 and multiple load members 51D, 53a and 53b involved in this modified example. Specifically, Figure 13 It is a diagram in which multiple electrodes 4 and multiple load components 51D, 53a and 53b are projected onto the xy plane.

[0178] Figure 14 This is a partial cross-sectional view of the surface acoustic wave resonator 1 involved in this modified example. Specifically, Figure 14 yes Figure 13 The cross-section at the xiv-xiv line.

[0179] in addition, Figure 13 as well as Figure 14 This is used to illustrate the typical positional relationship of the multiple electrodes 4 and the multiple load members 51D, 53a, and 53b. The positional relationship of the multiple electrodes 4 and the multiple load members 51D, 53a, and 53b is not limited to... Figure 13 as well as Figure 14 The positional relationship. Therefore, the following description of the multiple electrodes 4 and the multiple load members 51D, 53a and 53b should not be interpreted restrictively.

[0180] The plurality of load members 51D is an example of a plurality of first load members, and is made of dielectric. In this modified example, the plurality of load members 51D are also, like the plurality of load members 51 in Embodiment 1, a plurality of load films (an example of a plurality of first load films) disposed separately on the substrate 3. Each of the plurality of load members 51D, when viewed from above the substrate 3, at least partially overlaps with at least one corresponding electrode finger. Thus, the plurality of load members 51D can provide additional mass to several of the plurality of electrode fingers 421. The same material as the plurality of load members 51D in Embodiment 1 can be used as the material for the plurality of load members 51D.

[0181] The multiple load members 53a and 53b are examples of multiple second load members, made of dielectric or conductive material. The multiple load members 53a and 53b are multiple load films (an example of multiple second load films) disposed on the substrate 3. Load member 53a, viewed from above the substrate 3, at least partially overlaps with the leading ends of multiple electrode fingers 411a. Load member 53b, viewed from above the substrate 3, at least partially overlaps with the leading ends of multiple electrode fingers 411b. Thus, the multiple load members 53a and 53b can add mass to the leading ends of the multiple electrode fingers 411a and 411b of the IDT electrode 41. The same material as the multiple load members 51D can be used as the material for load members 53a and 53b. Alternatively, the material for load members 53a and 53b can be different from the material for load member 51D.

[0182] like Figure 14As shown, the thickness t53 of the load member 53b on the plurality of electrode fingers 411b is smaller than the thickness of the load member 51D on the plurality of electrode fingers 421. Similarly, the thickness of the load member 53a on the plurality of electrode fingers 411a is also smaller than the thickness t51a of the load member 51D on the plurality of electrode fingers 421. That is, the thickness of the plurality of load members 51D is larger than the thickness of the plurality of load members 53a and 53b. Here, the thickness of the load member is obtained by averaging the thicknesses of the load members on the top surface of the plurality of electrode fingers.

[0183] Furthermore, the thickness of the multiple load members 51D can also be the same as the thickness of the multiple load members 53a and 53b. The so-called same thickness of the two objects does not mean that they are strictly the same, but that an error range (±10%) is allowed that can be considered substantially the same.

[0184] As described above, the surface acoustic wave resonator 1 of this modified example may also include a plurality of load members 53a and 53b that, when viewed from above the substrate 3, at least partially overlap the front ends of the electrode fingers 411a and 411b of the IDT electrode 41, among the plurality of electrode fingers 411a, 411b and 421.

[0185] Therefore, it is also possible to suppress ripples caused by the transverse die by suppressing the transverse die in the piston mode.

[0186] For example, in the surface acoustic wave resonator 1 of this modified example, the plurality of load members 51D may also be a plurality of first load films disposed on the substrate 3, and the plurality of load members 53a and 53b may also be a plurality of second load films made of the same material as the plurality of load members 51D and disposed on the substrate 3.

[0187] Therefore, multiple load members 51D and multiple load members 53a and 53b can be film-formed using the same material, which simplifies the manufacturing process of the surface acoustic wave resonator 1.

[0188] For example, in the surface acoustic wave resonator 1 involved in this modification, the thickness of the plurality of load members 51D can also be the same as the thickness of the plurality of load members 53a and 53b.

[0189] Therefore, multiple load components 51D and multiple load components 53a and 53b can be film-formed in a single process, which can further simplify the manufacturing process of the surface acoustic wave resonator 1.

[0190] For example, in the surface acoustic wave resonator 1 of this modified example, the thickness of the plurality of load members 51D may also be greater than the thickness of the plurality of load members 53a and 53b.

[0191] Therefore, a suitable film thickness can be adopted in the plurality of load members 51D used to improve the Q value and the plurality of load members 53a and 53b used to press the cross die. In particular, by using the plurality of load members 51D used to improve the Q value to be thicker than the plurality of load members 53a and 53b used to press the cross die, it is possible to seek further improvement in the Q value.

[0192] (Variation 5 of Implementation Method 1)

[0193] Next, a variation of Embodiment 1, number 5, will be described. The main difference between this variation and Embodiment 1 is that an IDT electrode and a reflective electrode are disposed on both sides of the piezoelectric layer 31. Hereinafter, this variation will be described focusing on the differences from Embodiment 1, referring to… Figure 1 , Figure 15 as well as Figure 16 Please provide an explanation.

[0194] Figure 15 This is a top view of the surface acoustic wave resonator 1 involved in this variation, which is a view from the positive z-axis perspective of the main surface 31b side of the piezoelectric layer 31. Figure 16 This is a cross-sectional view of the surface acoustic wave resonator 1 involved in this modified example. Figure 16 The cross-section of surface acoustic wave resonator 1 in the diagram is... Figure 15 The cross section at the xvi-xvi line.

[0195] The piezoelectric layer 31 has opposing main surfaces 31a and 31b. Main surface 31a is an example of a first main surface, and main surface 31b is an example of a second main surface. On main surface 31a... Figure 1 As shown, multiple electrodes 4 are arranged on the main surface 31b, such as... Figure 15 Multiple electrodes 6 are arranged as shown.

[0196] Multiple electrodes 6 are an example of at least one second electrode, comprising an IDT electrode 61 and a pair of reflective electrodes 62.

[0197] IDT electrode 61 is an example of a second IDT electrode, comprising two interleaved comb-shaped electrodes disposed on piezoelectric layer 31, capable of converting electrical signals into surface acoustic waves and performing inverse conversion. IDT electrode 61 includes multiple electrode fingers 611a and 611b and busbar electrodes 612a and 612b.

[0198] Multiple electrode fingers 611a and 611b are an example of multiple second electrode fingers, arranged alternately along the x-axis (second axis) and extending along the y-axis (second axis) respectively. One end of the multiple electrode fingers 611a is connected to the busbar electrode 612a and extends from the busbar electrode 612a in the negative direction of the y-axis. One end of the multiple electrode fingers 611b is connected to the busbar electrode 612b and extends from the busbar electrode 612b in the positive direction of the y-axis. Alternatively, the multiple electrode fingers 611a and 611b may not be arranged alternately one by one; for example, they may be arranged in two or more alternating positions.

[0199] Furthermore, in a top view of substrate 3, the plurality of electrode fingers 611a and 611b overlap one-to-one with the plurality of electrode fingers 411a and 411b. The plurality of electrode fingers 411a and 611a are excited in phase, and the plurality of electrode fingers 411b and 611b are excited in phase. This suppresses stray modes such as higher-order modes. Alternatively, in a top view of substrate 3, the plurality of electrode fingers 611a and 611b may not completely overlap with the plurality of electrode fingers 411a and 411b. For example, a portion of the plurality of electrode fingers 611a and 611b may not overlap with the plurality of electrode fingers 411a and 411b, and a portion of the plurality of electrode fingers 411a and 411b may not overlap with the plurality of electrode fingers 611a and 611b.

[0200] Busbar electrode 612a extends along the x-axis and is connected to one end of a plurality of electrode fingers 611a. Busbar electrode 612a is arranged parallel to busbar electrode 612b and is separated from busbar electrode 612b in the positive direction of the y-axis.

[0201] Busbar electrode 612b extends along the x-axis and is connected to one end of a plurality of electrode fingers 611b. Busbar electrode 612b is arranged parallel to busbar electrode 612a and is separated from busbar electrode 612a in the negative y-axis direction.

[0202] A pair of reflective electrodes 62 is an example of a pair of second reflective electrodes, configured to sandwich the IDT electrode 61 in the x-axis direction in order to confine a given high-frequency signal resonating in the IDT electrode 61 within the IDT electrode 61. That is, the IDT electrode 61 is disposed between the pair of reflective electrodes 62 in the x-axis direction. Each pair of reflective electrodes 62 includes a plurality of electrode fingers 621 and busbar electrodes 622a and 622b.

[0203] Multiple electrode fingers 621 are an example of multiple second electrode fingers, arranged along the x-axis and extending along the y-axis respectively. The two ends of the multiple electrode fingers 621 are connected to busbar electrodes 622a and 622b. Busbar electrode 622a extends along the x-axis and is connected to one end of the multiple electrode fingers 621. Busbar electrode 622b extends along the x-axis, is arranged parallel to busbar electrode 622a, and is connected to the other end of the multiple electrode fingers 621.

[0204] The materials used for the IDT electrode 61 and the pair of reflective electrodes 62 can be, for example, aluminum, titanium, gold, silver, copper, platinum, tungsten, molybdenum, ruthenium, or any combination thereof. However, the materials of the IDT electrode 61 and the pair of reflective electrodes 62 are not limited to these. Furthermore, the materials of the IDT electrode 61 and the pair of reflective electrodes 62 can be different from each other or the same.

[0205] The plurality of load members 71 is an example of a plurality of third load members, and is made of dielectric. In this embodiment, the plurality of load members 71 are a plurality of load films (an example of a plurality of first load films) disposed separately on the substrate 3. Each of the plurality of load members 71, when viewed from above the substrate 3, at least partially overlaps with at least one corresponding electrode finger. Thus, the plurality of load members 71 can provide additional mass to several of the plurality of electrode fingers 611a, 611b, and 621.

[0206] The materials used for the multiple load members 71 can be dielectric materials, specifically tantalum pentoxide (Ta2O5), niobium pentoxide (Nb2O5), tungsten oxide (VI) (WO3), silicon nitride (SiN), titanium oxide (IV) (TiO2), cerium oxide (IV) (CeO2), hafnium oxide (IV) (HfO2), ytterbium oxide (III) (Yb2O3), silicon dioxide, bauxite, or any combination thereof, and are not limited to these. By using a dielectric material with a higher density than the protective film 52, the multiple load members 71 can be made thinner. Furthermore, the multiple load members 71 can also be made of different materials.

[0207] The electrode finger region 3b on the main surfaces 31a and 31b of the piezoelectric layer 31 is a region where multiple electrode fingers 411a, 411b, 421, 611a, 611b, and 621 are disposed, and is equally divided into a first sub-region 3b1, a second sub-region 3b2, and a third sub-region 3b3 in the y-axis direction. The electrode finger region 3b is defined as a rectangular region that surrounds the multiple electrode fingers 411a, 411b, 421, 611a, 611b, and 621 with a minimum area. Figure 1 as well as Figure 15In the diagram, the first sub-region 3b1, the second sub-region 3b2, and the third sub-region 3b3 are the left, central, and right portions of the electrode finger region 3b, respectively. The second sub-region 3b2 is located between the first sub-region 3b1 and the third sub-region 3b3.

[0208] Furthermore, the cross-sectional structure and configuration of the multiple electrode fingers 611a, 611b, 621 and the multiple load members 71 are the same as in Embodiment 1, therefore, the illustrations and descriptions are omitted.

[0209] Furthermore, the structure of the surface acoustic wave resonator 1 is not limited to Figure 1 , Figure 15 as well as Figure 16 The structure can be varied. For example, the surface acoustic wave resonator 1 may include only one of the multiple load members 51 and 71. That is, the load members may overlap only one of the multiple electrodes 4 disposed on the main surface 31a and the multiple electrodes 6 disposed on the main surface 31b.

[0210] As described above, in the surface acoustic wave resonator 1 of this modified example, the piezoelectric layer 31 may also include opposing main surfaces 31a and 31b, and at least one electrode 4 may be disposed on one of the main surfaces 31a and 31b. The surface acoustic wave resonator 1 may also include at least one electrode 6 disposed on the other of the main surfaces 31a and 31b and including an IDT electrode 61. The at least one electrode 6 may also include a plurality of electrode fingers 611a, 611b and 621 arranged along the x-axis and extending along the y-axis perpendicular to the x-axis on the substrate 3. The plurality of electrode fingers 611a, 611b and 621 may also overlap one-to-one with the plurality of electrode fingers 411a, 411b and 421 when viewed from above the substrate 3.

[0211] As a result, multiple electrode fingers 611a and 411a are excited in phase, as are multiple electrode fingers 611b and 411b. This allows for the suppression of stray high-order modes and other unwanted signals.

[0212] For example, the surface acoustic wave resonator 1 according to this modification may also include a plurality of load members 71 disposed separately on or within the substrate 3 and made of dielectric. Each of the plurality of load members 71 may at least partially overlap with at least one corresponding electrode finger when viewed from above the substrate 3. The number of electrode fingers disposed in the first sub-region 3b1 that overlap with the plurality of load members 71 and the number of electrode fingers disposed in the third sub-region 3b3 that overlap with the plurality of load members 71 may be greater than the number of electrode fingers disposed in the second sub-region 3b2 that overlap with the plurality of load members 71. The plurality of load members 71 may also include two or more load members 71 that overlap with the electrode fingers disposed in the first sub-region 3b1 and two or more load members 71 that overlap with the electrode fingers disposed in the third sub-region 3b3.

[0213] Therefore, by adding mass to the multiple electrode fingers 611a, 611b, and 621 disposed in the first sub-region 3b1 and the third sub-region 3b3 using multiple load members 71, the reflectivity can be improved, thereby enhancing the effect of containing surface acoustic waves into the surface acoustic wave resonator 1. As a result, the Q value of the surface acoustic wave resonator 1 can be improved. Furthermore, since the multiple load members 71 are made of dielectric, it becomes easier to ensure the distance between adjacent electrode fingers compared to the case where the multiple load members 71 are made of conductor, thus suppressing the decrease in power withstand capability.

[0214] For example, in the surface acoustic wave resonator 1 of this variant, at least one electrode 6 may also include a pair of reflective electrodes 62, and an IDT electrode 61 may also be disposed between the pair of reflective electrodes 62.

[0215] Therefore, by means of a pair of reflective electrodes 62, the effect of sealing the surface acoustic wave into the surface acoustic wave resonator 1 can be further improved, and the Q value of the surface acoustic wave resonator 1 can be further improved.

[0216] (Implementation Method 2)

[0217] Next, implementation method 2 will be described. In this implementation method, refer to... Figure 17 as well as Figure 18 A surface acoustic wave filter using the surface acoustic wave resonator 1 according to Embodiment 1 or its variations will be described.

[0218] [2.1 Circuit structure of surface acoustic wave filter 100]

[0219] Figure 17 This is a circuit structure diagram of the surface acoustic wave filter 100 according to this embodiment. Additionally, Figure 17This is used to illustrate a typical circuit structure of the surface acoustic wave filter 100. The circuit structure of the surface acoustic wave filter 100 is not limited to... Figure 17 The circuit structure is described below. Therefore, the following description of the surface acoustic wave filter 100 should not be interpreted restrictively.

[0220] The surface acoustic wave filter 100 is a trapezoidal surface acoustic wave filter, which has multiple series arm resonators 101 to 104 and multiple parallel arm resonators 111 to 114.

[0221] Multiple series-arm resonators 101 to 104 are connected in series between the input terminal 121 and the output terminal 122. Specifically, one end of series-arm resonator 101 is connected to the input terminal 121, and the other end of series-arm resonator 101 is connected to one end of series-arm resonator 102. The other end of series-arm resonator 102 is connected to one end of series-arm resonator 103. The other end of series-arm resonator 103 is connected to one end of series-arm resonator 104. The other end of series-arm resonator 104 is connected to the output terminal 122.

[0222] Multiple parallel-arm resonators 111-114 are connected in parallel between the path connecting input terminal 121 and output terminal 122 and ground. Specifically, parallel-arm resonator 111 is connected between the path connecting series-arm resonators 101 and 102 and ground. Parallel-arm resonator 112 is connected between the path connecting series-arm resonators 102 and 103 and ground. Parallel-arm resonator 113 is connected between the path connecting series-arm resonators 103 and 104 and ground. Parallel-arm resonator 114 is connected between the path connecting series-arm resonator 104 and output terminal 122 and ground.

[0223] In this embodiment, at least one of the multiple series arm resonators 101-104 and the multiple parallel arm resonators 111-114 is the surface acoustic wave resonator 1 involved in Embodiment 1 or its variations.

[0224] For example, the surface acoustic wave (SAW) resonator 1 may be included only in the parallel arm resonators 111-114 among the multiple series arm resonators 101-104 and the multiple parallel arm resonators 111-114. That is, the SAW resonator 1 may be included in the multiple parallel arm resonators 111-114, but not in the multiple series arm resonators 101-104.

[0225] Furthermore, in the case where multiple series arm resonators 101-104 include surface acoustic wave resonators 1 and multiple parallel arm resonators 111-114 include surface acoustic wave resonators 1, it is also possible that the number, shape, size, or any combination thereof of the multiple load members 51, 51A, 51B, 51C, or 51D differs between the surface acoustic wave resonators 1 included in the multiple series arm resonators 101-104 and the surface acoustic wave resonators 1 included in the multiple parallel arm resonators 111-114.

[0226] For example, in the surface acoustic wave resonator 1 included in the multiple series arm resonators 101 to 104, the area of ​​the portion of the multiple load members 51, 51A, 51B, 51C or 51D overlapping with the multiple electrode fingers may also be smaller than the area of ​​the portion of the multiple load members 51, 51A, 51B, 51C or 51D overlapping with the multiple electrode fingers in the surface acoustic wave resonator 1 included in the multiple parallel arm resonators 111 to 114.

[0227] For example, the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the surface acoustic wave resonator 1 included in the multiple series arm resonators 101 to 104 may be less than the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the surface acoustic wave resonator 1 included in the multiple parallel arm resonators 111 to 114.

[0228] For example, the thickness of the multiple load members 51, 51A, 51B, 51C or 51D of the surface acoustic wave resonator 1 included in the multiple series arm resonators 101 to 104 may also be less than the thickness of the multiple load members 51, 51A, 51B, 51C or 51D of the surface acoustic wave resonator 1 included in the multiple parallel arm resonators 111 to 114.

[0229] Furthermore, in the case where two or more series arm resonators are each surface acoustic wave resonators 1, the number, shape, size, or any combination thereof of the multiple load members 51, 51A, 51B, 51C, or 51D may differ depending on their distance from the input terminal 121.

[0230] For example, when there are two or more series arm resonators, each of which is a surface acoustic wave resonator 1, the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the series arm resonator closer to the input terminal 121 (the first series arm resonator) may be less than the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the series arm resonator farther away from the input terminal 121 (the second series arm resonator).

[0231] Furthermore, the relative distance between the two series arm resonators and the input terminal 121 is determined according to the circuit structure of the surface acoustic wave filter 100. Specifically, the series arm resonator farther from the input terminal 121 (e.g., series arm resonator 104) is connected to the input terminal 121 via the series arm resonator closer to the input terminal 121 (e.g., series arm resonator 101). Conversely, the series arm resonator closer to the input terminal 121 (e.g., series arm resonator 101) is not connected to the input terminal 121 via the series arm resonator farther from the input terminal 121 (e.g., series arm resonator 104).

[0232] Similarly, in the case where two or more parallel arm resonators are each surface acoustic wave resonators 1, the number, shape, size, or any combination thereof of the multiple load members 51, 51A, 51B, 51C, or 51D may differ depending on their distance from the input terminal 121.

[0233] For example, when there are two or more parallel arm resonators, each of which is a surface acoustic wave resonator 1, the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the parallel arm resonator closer to the input terminal 121 (the first parallel arm resonator) may be less than the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the parallel arm resonator farther away from the input terminal 121 (the second parallel arm resonator).

[0234] Furthermore, the relative distance between the two parallel arm resonators and the input terminal 121 is determined according to the circuit structure of the surface acoustic wave filter 100. Specifically, the node on the path connecting the input terminal 121 and the output terminal 122 (hereinafter referred to as the series path) that connects the parallel arm resonator (e.g., parallel arm resonator 114) farther from the input terminal 121 is connected to the input terminal 121 via a node on the series path that connects the parallel arm resonator (e.g., parallel arm resonator 111) closer to the input terminal 121. Conversely, the node on the series path that connects the parallel arm resonator (e.g., parallel arm resonator 111) closer to the input terminal 121 is not connected to the input terminal 121 via a node on the series path that connects the parallel arm resonator (e.g., parallel arm resonator 114) farther from the input terminal 121.

[0235] Furthermore, the surface acoustic wave filter using the surface acoustic wave resonator 1 according to Embodiment 1 or its variations is not limited to the trapezoidal surface acoustic wave filter 100. For example, the surface acoustic wave filter may also include a longitudinally coupled surface acoustic wave resonator.

[0236] [2.2 Installation Example of Surface Acoustic Wave Filter 100]

[0237] Next, refer to Figure 18 An example of mounting a surface acoustic wave filter 100 configured as described above will be explained. Figure 18 This is a top view of the surface acoustic wave filter 100 according to this embodiment. Figure 18 In the middle, the shadow lines represent wiring.

[0238] in addition, Figure 18 This is one example of the installation of the surface acoustic wave filter 100, which can be installed using a variety of circuit mounting methods and any of the circuit technologies used. Therefore, the following description of the surface acoustic wave filter 100 should not be interpreted limitingly.

[0239] exist Figure 18 In this configuration, input terminal 121 is located at the upper left corner of substrate 3, and output terminal 122 is located at the lower right corner of substrate 3. Multiple ground terminals 123 are discretely arranged on substrate 3. Multiple series arm resonators 101 to 104 are arranged sequentially in the negative y-axis direction, and multiple parallel arm resonators 111 to 114 are arranged sequentially in the negative y-axis direction.

[0240] The arrangement of the multiple series arm resonators 101-104 and / or the multiple parallel arm resonators 111-114 on the substrate 3, which includes the surface acoustic wave resonator 1 according to Embodiment 1 or its variations, can also be determined based on the arrangement of the multiple series arm resonators 101-104 and the multiple parallel arm resonators 111-114 as configured in this way.

[0241] For example, the surface acoustic wave resonator 1 described in Embodiment 1 or its variations can also be used for each of the multiple resonators arranged along the x-axis. In this case, Figure 18 In this design, surface acoustic wave resonators 1 are used for both the series arm resonator 102 and the parallel arm resonator 111, and surface acoustic wave resonators 1 are used for both the series arm resonator 103 and the parallel arm resonator 113.

[0242] [2.3 Summary]

[0243] As described above, the surface acoustic wave filter 100 according to this embodiment includes at least one series arm resonator 101 to 104 and at least one parallel arm resonator 111 to 114. At least one of the at least one series arm resonator 101 to 104 and at least one parallel arm resonator 111 to 114 is the surface acoustic wave resonator 1 described in Embodiment 1 or its variations.

[0244] Therefore, by using the surface acoustic wave resonator 1 described in Embodiment 1 or its variations in the trapezoidal surface acoustic wave filter 100, it is possible to improve the characteristics of the surface acoustic wave filter 100 (e.g., reduce loss and reduce ripple).

[0245] For example, in the surface acoustic wave filter 100 of this embodiment, at least one parallel arm resonator 111 to 114 may include a surface acoustic wave resonator 1, and at least one series arm resonator 101 to 104 may not include a surface acoustic wave resonator 1.

[0246] Therefore, by using a surface acoustic wave (SAW) resonator 1 for at least one parallel arm resonator 111-114, the Q value of the at least one parallel arm resonator 111-114 can be improved, thereby improving the characteristics of the SAW filter 100. Furthermore, by not using the SAW resonator 1 for at least one series arm resonator 101-104, the decrease in power withstand capability and the increase in longitudinal mode ripple caused by the multiple load members 51, 51A, 51B, 51C, or 51D can be suppressed. In particular, as the passband shifts towards higher frequencies with increasing temperature, the power withstand capability of the series arm resonator becomes more demanding than that of the parallel arm resonator, thus the effect of suppressing the decrease in power withstand capability of at least one series arm resonator 101-104 is greater.

[0247] For example, in the surface acoustic wave filter 100 according to this embodiment, at least one series arm resonator 101 to 104 may also include a surface acoustic wave resonator 1, and at least one parallel arm resonator 111 to 114 may also include a surface acoustic wave resonator 1. The area of ​​the portion of the multiple load members 51, 51A, 51B, 51C or 51D in the surface acoustic wave resonator 1 included in at least one series arm resonator 101 to 104 that overlaps with the multiple electrode fingers when viewed from the top of the substrate 3 may also be smaller than the area of ​​the portion of the multiple load members 51, 51A, 51B, 51C or 51D in the surface acoustic wave resonator 1 included in at least one parallel arm resonator 111 to 114 that overlaps with the multiple electrode fingers when viewed from the top of the substrate 3.

[0248] Therefore, it is possible to suppress the longitudinal mode in the surface acoustic wave resonator 1 included in at least one series arm resonator 101-104 and suppress the ripple caused by the longitudinal mode, thereby improving the pass-through characteristics of the surface acoustic wave filter 100.

[0249] For example, in the surface acoustic wave filter 100 of this embodiment, at least one series arm resonator 101 to 104 may also include a surface acoustic wave resonator 1, and at least one parallel arm resonator 111 to 114 may also include a surface acoustic wave resonator 1. The number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the surface acoustic wave resonator 1 included in at least one series arm resonator 101 to 104 may be less than the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the surface acoustic wave resonator 1 included in at least one parallel arm resonator 111 to 114.

[0250] Therefore, it is possible to suppress the longitudinal mode in the surface acoustic wave resonator 1 included in at least one series arm resonator 101-104 and suppress the ripple caused by the longitudinal mode, thereby improving the pass-through characteristics of the surface acoustic wave filter 100.

[0251] For example, in the surface acoustic wave filter 100 of this embodiment, at least one series arm resonator 101 to 104 may also include a surface acoustic wave resonator 1, and at least one parallel arm resonator 111 to 114 may also include a surface acoustic wave resonator 1. The thickness of the plurality of load members 51, 51A, 51B, 51C or 51D of the surface acoustic wave resonator 1 included in at least one series arm resonator 101 to 104 may also be less than the thickness of the plurality of load members 51, 51A, 51B, 51C or 51D of the surface acoustic wave resonator 1 included in at least one parallel arm resonator 111 to 114.

[0252] Therefore, the stopband ripple caused by the surface acoustic wave resonator 1 included by at least one parallel arm resonator 111-114 can be suppressed, and the pass characteristics of the surface acoustic wave filter 100 can be improved.

[0253] For example, in the surface acoustic wave filter 100 according to this embodiment, at least one series arm resonator 101 to 104 may also include a first series arm resonator 101 to 104 connected in series between the input terminal 121 and the output terminal 122, and a second series arm resonator 101 to 104 that is farther away from the input terminal 121 than the first series arm resonator 101 to 104. The first series arm resonator 101 to 104 and the second series arm resonator 101 to 104 may each be a surface acoustic wave resonator 1. The number of electrode fingers overlapping with the plurality of load members 51, 51A, 51B, 51C or 51D in the first series arm resonator 101 to 104 may also be less than the number of electrode fingers overlapping with the plurality of load members 51, 51A, 51B, 51C or 51D in the second series arm resonator 101 to 104.

[0254] Therefore, the decrease in power withstand capability in the series arm resonator closer to the input terminal 121 can be suppressed, and the power withstand capability of the surface acoustic wave filter 100 can be improved. In particular, the resonator closer to the input terminal 121 is subjected to higher power, so the effect of improving the power withstand capability of the surface acoustic wave filter 100 is greater.

[0255] For example, in the surface acoustic wave filter 100 according to this embodiment, at least one parallel arm resonator 111-114 may also include multiple parallel arm resonators 111-114 connected in parallel between the path connecting the input terminal 121 and the output terminal 122 and ground. The multiple parallel arm resonators 111-114 may also include a first parallel arm resonator 111-114 and a second parallel arm resonator that is farther from the input terminal 121 than the first parallel arm resonator 111-114. Resonators 111-114, the first parallel arm resonators 111-114 and the second parallel arm resonators 111-114 can each be surface acoustic wave resonators 1. The number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the first parallel arm resonators 111-114 can also be less than the number of electrode fingers overlapping with multiple load members 51, 51A, 51B, 51C or 51D in the second parallel arm resonators 111-114.

[0256] Therefore, the decrease in power withstand capability in the parallel arm resonator closer to the input terminal 121 can be suppressed, and the power withstand capability of the surface acoustic wave filter 100 can be improved. In particular, the resonator closer to the input terminal 121 is subjected to higher power, so the effect of improving the power withstand capability of the surface acoustic wave filter 100 is greater.

[0257] For example, in the surface acoustic wave filter 100 of this embodiment, at least two of the at least one series arm resonator 101 to 104 and at least one parallel arm resonator 111 to 114 may also be surface acoustic wave resonators 1, and may also be arranged along the x-axis on the substrate.

[0258] Therefore, a surface acoustic wave (SAW) resonator 1 can be used for at least two resonators arranged in the propagation direction (x-axis direction) of the SAW. In a SAW resonator 1 that includes multiple load members 51, 51A, 51B, 51C, or 51D, the sealing effect of the SAW can be improved by using multiple load members 51, 51A, 51B, 51C, or 51D, thus reducing the number of electrode fingers 421 of the reflecting electrode 42. As a result, the size of the reflecting electrode 42 in the propagation direction can be reduced, and the installation size of the SAW resonator 1 can be reduced. In particular, in at least two resonators arranged in the propagation direction, the size in the propagation direction is larger, thus the effect of reducing the installation size of the SAW resonator 1 is greater.

[0259] (Implementation Method 3)

[0260] Next, implementation method 3 will be described. In this implementation method, refer to... Figure 19 A multiplexer using the surface acoustic wave filter 100 according to Embodiment 2 will be described.

[0261] [3.1 Circuit structure of multiplexer 200]

[0262] Figure 19 This is a circuit diagram of the multiplexer 200 involved in this embodiment. Additionally, Figure 19 This is used to illustrate a typical circuit structure of the multiplexer 200; the circuit structure of the multiplexer 200 is not limited to... Figure 19 The circuit structure is as follows. Therefore, the following description of the multiplexer 200 should not be interpreted restrictively.

[0263] The multiplexer 200 includes transmit filters 201 and 203 and receive filters 202 and 204.

[0264] The transmit filter 201 has a passband that includes the transmit band of frequency band A, allowing the transmit signal of frequency band A to pass through. The transmit filter 201 is connected between the antenna connection terminal 211 and the PA connection terminal 212.

[0265] The receiving filter 202 has a passband that includes the receiving band of frequency band A, allowing the received signal of frequency band A to pass through. The receiving filter 202 is connected between the antenna connection terminal 211 and the LNA connection terminal 213.

[0266] The transmit filter 203 has a passband that includes the transmit band of frequency band B, allowing transmit signals of frequency band B to pass through. The transmit filter 203 is connected between the antenna connection terminal 211 and the PA connection terminal 214. Alternatively, the transmit filter 203 may not be included in the multiplexer 200.

[0267] The receiver filter 204 has a passband that includes the receive band of frequency band B, allowing received signals of frequency band B to pass through. The receiver filter 204 is connected between the antenna connection terminal 211 and the LNA connection terminal 215. Alternatively, the receiver filter 204 may not be included in the multiplexer 200.

[0268] Frequency bands A and B are frequency bands used in communication systems built using Radio Access Technology (RAT), and are predefined by standardization organizations such as 3GPP (3rd Generation Partnership Project) and IEEE (Institute of Electrical and Electronics Engineers). Examples of communication systems include 5G NR (5th Generation New Radio) systems, LTE (Long Term Evolution) systems, and WLAN (Wireless Local Area Network) systems.

[0269] Antenna connection terminal 211 is an external connection terminal for connecting to the antenna (ANT). Antenna connection terminal 211 can also be switched to connect to the antenna.

[0270] PA connection terminal 212 is an external connection terminal for connecting to a power amplifier (PA). PA connection terminal 212 can also be switched to connect to a power amplifier.

[0271] LNA connector 213 is an external connector for connection to a low-noise amplifier (LNA). LNA connector 213 can also be switched to connect to a low-noise amplifier.

[0272] PA connection terminal 214 is an external connection terminal for connecting to a power amplifier (PA). PA connection terminal 214 can also be switched to connect to a power amplifier.

[0273] LNA connector 215 is an external connector for connection to a low-noise amplifier (LNA). LNA connector 215 can also be switched to connect to a low-noise amplifier.

[0274] In this embodiment, at least one of the transmitting filters 201 and 203 and the receiving filters 202 and 204 included in the multiplexer 200 is the surface acoustic wave filter 100 according to embodiment 2.

[0275] For example, among the transmitting filters 201 and 203 and the receiving filters 202 and 204, only the receiving filters 202 and / or 204 are surface acoustic wave filters 100. That is, the receiving filters 202 and / or 204 can be the surface acoustic wave filters 100 according to Embodiment 2, and the transmitting filters 201 and 203 may not be surface acoustic wave filters 100.

[0276] For example, if the transmitting filter 201 and / or 203 is a surface acoustic wave (SAW) filter 100, the SAW resonator 104 among the plurality of series arm resonators 101 to 104 that is closest to the antenna connection terminal 211 (output terminal 122) may also be the SAW resonator 1 according to Embodiment 1. Conversely, the series arm resonators 101 to 103 may not be SAW resonators 1.

[0277] For example, if the transmitting filter 201 and / or 203 is a surface acoustic wave (SAW) filter 100, the parallel arm resonator 114 closest to the antenna connection terminal 211 (output terminal 122) among the plurality of parallel arm resonators 111 to 114 can also be the SAW resonator 1 according to Embodiment 1. Conversely, the parallel arm resonators 111 to 113 may not be SAW resonators 1.

[0278] For example, when the receiving filter 202 and / or 204 is a surface acoustic wave (SAW) filter 100, the SAW resonator 101 among the plurality of SAW resonators 101 to 104 that is closest to the antenna connection terminal 211 (input terminal 121) may also be the SAW resonator 1 according to Embodiment 1. Conversely, the SAW resonators 102 to 104 may not be SAW resonators 1.

[0279] For example, when the receiving filter 202 and / or 204 is a surface acoustic wave filter 100, the parallel arm resonator 111, which is closest to the antenna connection terminal 211 (input terminal 121) among the plurality of parallel arm resonators 111 to 114, can also be the surface acoustic wave resonator 1 according to Embodiment 1. Conversely, the parallel arm resonators 112 to 114 may not be surface acoustic wave resonators 1.

[0280] [3.2 Summary]

[0281] As described above, the multiplexer 200 of this embodiment includes: a transmit filter 201 connected between the antenna connection terminal 211 and the PA connection terminal 212, having a passband that includes the transmit band of frequency band A; and a receive filter 202 connected between the antenna connection terminal 211 and the LNA connection terminal 213, having a passband that includes the receive band of frequency band A. At least one of the transmit filter 201 and the receive filter 202 is the surface acoustic wave filter 100 described in Embodiment 2.

[0282] Therefore, by using the surface acoustic wave filter 100 described in Embodiment 2 in the multiplexer 200, it is possible to improve the characteristics of the multiplexer 200 (e.g., reduce loss and reduce ripple).

[0283] For example, in the multiplexer 200 of this embodiment, the receiving filter 202 may also be a surface acoustic wave filter 100, and the transmitting filter 201 may not be a surface acoustic wave filter 100.

[0284] Therefore, by using the surface acoustic wave filter 100 on the receiving filter 202, signal loss can be reduced and receiving sensitivity can be improved. Furthermore, by not using the surface acoustic wave filter 100 on the transmitting filter 201, the decrease in power tolerance caused by multiple load components 51, 51A, 51B, 51C or 51D can be avoided in the transmitting filter 201, which requires higher power tolerance.

[0285] For example, in the multiplexer 200 of this embodiment, the transmitting filter 201 may also be a surface acoustic wave filter 100 that includes a plurality of series arm resonators 101 to 104 connected in series between the antenna connection terminal 211 (output terminal 122) and the PA connection terminal 212 (input terminal 121). The series arm resonator 104 closest to the antenna connection terminal 211 among the plurality of series arm resonators 101 to 104 may also be the surface acoustic wave resonator 1 described in Embodiment 1 or its variations.

[0286] Therefore, by using the surface acoustic wave resonator 1 described in Embodiment 1 or its variations on the series arm resonator 104 closest to the antenna connection terminal 211, the characteristics of the transmitting filter 201 can be improved. In particular, by improving the Q value of the series arm resonator 104 closest to the antenna connection terminal 211 that connects multiple filters (transmitting filter 201 and receiving filter 202), the characteristics of the transmitting filter 201 can be effectively improved.

[0287] For example, in the multiplexer 200 of this embodiment, the transmitting filter 201 may also be a surface acoustic wave filter 100 that includes multiple parallel arm resonators 111 to 114 connected in parallel between the path connecting the antenna connection terminal 211 (output terminal 122) and the PA connection terminal 212 (input terminal 121) and ground. The parallel arm resonator 114 closest to the antenna connection terminal 211 among the multiple parallel arm resonators 111 to 114 may also be the surface acoustic wave resonator 1 described in Embodiment 1 or its variations.

[0288] Therefore, by using the surface acoustic wave resonator 1 described in Embodiment 1 or its variations on the parallel arm resonator 114 closest to the antenna connection terminal 211, the characteristics of the transmitting filter 201 can be improved. In particular, by improving the Q value of the parallel arm resonator 114 closest to the antenna connection terminal 211 that connects multiple filters (transmitting filter 201 and receiving filter 202), the characteristics of the transmitting filter 201 can be effectively improved.

[0289] For example, in the multiplexer 200 of this embodiment, the receiving filter 202 may also be a surface acoustic wave filter 100 that includes a plurality of series arm resonators 101 to 104 connected in series between the antenna connection terminal 211 (input terminal 121) and the LNA connection terminal 213 (output terminal 122). The series arm resonator 101 closest to the antenna connection terminal 211 among the plurality of series arm resonators 101 to 104 may also be the surface acoustic wave resonator 1 described in Embodiment 1 or its variations.

[0290] Therefore, by using the surface acoustic wave resonator 1 described in Embodiment 1 or its variations on the series arm resonator 101 closest to the antenna connection terminal 211, the characteristics of the receiving filter 202 can be improved. In particular, by improving the Q value of the series arm resonator 101 closest to the antenna connection terminal 211 connecting multiple filters (receiving filter 202 and receiving filter 202), the characteristics of the receiving filter 202 can be effectively improved.

[0291] For example, in the multiplexer 200 of this embodiment, the receiving filter 202 may also be a surface acoustic wave filter 100 that includes multiple parallel arm resonators 111 to 114 connected in parallel between the path connecting the antenna connection terminal 211 (input terminal 121) and the LNA connection terminal 213 (output terminal 122) and ground. The parallel arm resonator 111 closest to the antenna connection terminal 211 among the multiple parallel arm resonators 111 to 114 may also be the surface acoustic wave resonator 1 described in Embodiment 1 or its variations.

[0292] Therefore, by using the surface acoustic wave resonator 1 described in Embodiment 1 or its variations on the parallel arm resonator 111 closest to the antenna connection terminal 211, the characteristics of the receiving filter 202 can be improved. In particular, by improving the Q value of the parallel arm resonator 111 closest to the antenna connection terminal 211 connecting multiple filters (transmitting filter 201 and receiving filter 202), the characteristics of the receiving filter 202 can be effectively improved.

[0293] (Other implementation methods)

[0294] The above description, based on embodiments, outlines one aspect of the surface acoustic wave (SAW) resonator, SAW filter, and multiplexer according to the present invention. However, the SAW resonator, SAW filter, and multiplexer involved in the present invention are not limited to the above embodiments. Other embodiments implemented by combining any of the constituent elements in the above embodiments, variations obtained by implementing the above embodiments with various modifications conceivable to those skilled in the art without departing from the spirit of the present invention, and various devices incorporating the above-described high-frequency circuits are also included in the present invention.

[0295] For example, in the circuit structures of the surface acoustic wave filters and multiplexers described in the above embodiments, other circuit elements and wiring can be inserted between the paths connecting the circuit elements and signal paths disclosed in the accompanying drawings. For example, in Figure 15 In the surface acoustic wave filter 100, an inductor and / or capacitor may also be connected in series and / or in parallel with any of the series arm resonators 101-104 and the parallel arm resonators 111-114.

[0296] For example, the surface acoustic wave resonator 1 described in the above embodiments is a single-mode surface acoustic wave resonator, but it is not limited to this. For example, the surface acoustic wave resonator 1 can also be a longitudinally coupled dual-mode surface acoustic wave resonator. Even in this case, the same effect as a single-mode surface acoustic wave resonator can be obtained.

[0297] Furthermore, in the above embodiments, the multiple electrode fingers included in the IDT electrode and the reflective electrode are linear in shape when viewed from above, but this is not a limitation. For example, the multiple electrode fingers included in the IDT electrode and / or the reflective electrode may also have at least a partially curved shape when viewed from above. In this case, the resonant frequencies or anti-resonant frequencies may be substantially the same in the intersection region of the multiple electrode fingers. Specifically, the IDT electrode and / or the reflective electrode may also include the electrode fingers described in Patent Document 2 (International Publication No. 2024 / 009660) or Patent Document 3 (International Publication No. 2024 / 135259).

[0298] The features of the surface acoustic wave resonator, surface acoustic wave filter, and multiplexer described below are shown.

[0299] <1>

[0300] A surface acoustic wave resonator, comprising:

[0301] The substrate includes a piezoelectric layer;

[0302] At least one electrode, disposed on the substrate, includes an IDT electrode; and

[0303] Multiple first load members, disposed separately on or within the substrate, are made of dielectric material.

[0304] The at least one electrode comprises: a plurality of electrode fingers arranged on the substrate along a first axis and extending respectively along a second axis perpendicular to the first axis.

[0305] Each of the plurality of first load members, when viewed from above on the substrate, at least partially overlaps with at least one corresponding electrode finger.

[0306] The number of electrode fingers overlapping with the plurality of first load members in the electrode fingers arranged in the first sub-region and the number of electrode fingers overlapping with the plurality of first load members in the electrode fingers arranged in the third sub-region are respectively greater than the number of electrode fingers overlapping with the plurality of first load members in the electrode fingers arranged in the second sub-region.

[0307] The first sub-region, the second sub-region, and the third sub-region are obtained by equally dividing the area on the substrate where the plurality of electrode fingers are disposed in the direction of the second axis.

[0308] The second sub-region is located between the first sub-region and the third sub-region.

[0309] The plurality of first load members include two or more first load members that overlap with the electrode fingers disposed in the first sub-region and two or more first load members that overlap with the electrode fingers disposed in the third sub-region.

[0310] <2>

[0311] according to <1> The surface acoustic wave resonator, wherein,

[0312] The at least one electrode also includes a pair of reflective electrodes.

[0313] The IDT electrode is disposed between the pair of reflective electrodes.

[0314] <3>

[0315] according to <2> The surface acoustic wave resonator, wherein,

[0316] At least one of the plurality of first load members, when viewed from above on the substrate, at least partially overlaps with at least one corresponding electrode finger of the IDT electrode.

[0317] At least one of the other first load members, when viewed from above the substrate, at least partially overlaps with at least one corresponding electrode of the reflective electrode.

[0318] <4>

[0319] according to <1> ~ <3> The surface acoustic wave resonator according to any one of the following, wherein,

[0320] The plurality of first load members correspond one-to-one with several of the plurality of electrode fingers.

[0321] <5>

[0322] according to <4> The surface acoustic wave resonator, wherein,

[0323] Each of the plurality of first load members overlaps with a portion of a corresponding electrode finger when viewed from above on the substrate.

[0324] <6>

[0325] according to <5> The surface acoustic wave resonator, wherein,

[0326] The midpoint of each of the plurality of first load members along the length of the first axis is offset along the first axis from the midpoint of the length of the corresponding electrode along the first axis in the direction of the center of the IDT electrode.

[0327] <7>

[0328] according to <1> ~ <6> The surface acoustic wave resonator according to any one of the following, wherein,

[0329] The plurality of first load members are a plurality of first load films disposed on the substrate.

[0330] The plurality of first load films at least partially cover several of the plurality of electrode fingers.

[0331] <8>

[0332] according to <7> The surface acoustic wave resonator, wherein,

[0333] In each of the plurality of first load films, the thickness of the first load film on the top surface of the corresponding at least one electrode finger is greater than the thickness of the first load film on the side surface of the corresponding at least one electrode finger.

[0334] <9>

[0335] according to <7> or <8> The surface acoustic wave resonator, wherein,

[0336] The surface acoustic wave resonator also features:

[0337] A protective film is disposed on the substrate, covering the substrate and at least a portion of the plurality of electrode fingers.

[0338] <10>

[0339] according to <9> The surface acoustic wave resonator, wherein,

[0340] The protective film is stacked on the plurality of first load films.

[0341] <11>

[0342] according to <9> or <10> The surface acoustic wave resonator, wherein,

[0343] The plurality of first load films are made of a different material than the protective film.

[0344] <12>

[0345] according to <11> The surface acoustic wave resonator, wherein,

[0346] The plurality of first loaded films comprise tantalum pentoxide, niobium pentoxide, tungsten oxide (VI), silicon nitride, titanium oxide (IV), cerium oxide (IV), hafnium oxide (IV), or ytterbium oxide (III).

[0347] The protective film is made of silicon dioxide or silicon nitride.

[0348] <13>

[0349] according to <1> ~ <6> The surface acoustic wave resonator according to any one of the following, wherein,

[0350] The plurality of first load members are disposed within the substrate.

[0351] <14>

[0352] according to <13> The surface acoustic wave resonator, wherein,

[0353] The substrate further includes a low-velocity layer, wherein the velocity of sound of the propagating bulk wave is lower than the velocity of sound of the elastic wave propagating in the piezoelectric layer.

[0354] The piezoelectric layer is disposed on the low-velocity layer.

[0355] The plurality of first load members are disposed within the low-sound-velocity layer.

[0356] <15>

[0357] according to <1> ~ <14> The surface acoustic wave resonator according to any one of the following, wherein,

[0358] The spacing between an electrode finger that overlaps with the plurality of first load members and an electrode finger that is adjacent to the electrode finger but does not overlap with the plurality of first load members is different from the spacing between two adjacent electrode fingers that overlap with the plurality of first load members, or the spacing between two adjacent electrode fingers that do not overlap with the plurality of first load members.

[0359] <16>

[0360] according to <1> ~ <15> The surface acoustic wave resonator according to any one of the following, wherein,

[0361] The duty cycle of two or more electrode fingers that overlap with the plurality of first load members is different from the duty cycle of two or more electrode fingers that do not overlap with any of the plurality of first load members.

[0362] <17>

[0363] according to <1> ~ <16> The surface acoustic wave resonator according to any one of the following, wherein,

[0364] The surface acoustic wave resonator further comprises: a plurality of second load members, which, when viewed from above the substrate, at least partially overlap the front end of the electrode finger of the IDT electrode among the plurality of electrode fingers.

[0365] <18>

[0366] according to <17> The surface acoustic wave resonator, wherein,

[0367] The plurality of first load members are a plurality of first load films disposed on the substrate.

[0368] The plurality of second load members are made of the same material as the plurality of first load films and are disposed on the substrate.

[0369] <19>

[0370] according to <18> The surface acoustic wave resonator, wherein,

[0371] The thickness of the plurality of first load films is the same as the thickness of the plurality of second load films.

[0372] <20>

[0373] according to <18> The surface acoustic wave resonator, wherein,

[0374] The thickness of the plurality of first load films is greater than the thickness of the plurality of second load films.

[0375] <21>

[0376] A surface acoustic wave filter, comprising:

[0377] At least one series arm resonator; and

[0378] At least one parallel arm resonator,

[0379] At least one of the at least series arm resonator and the at least parallel arm resonator is <1> ~ <20> The surface acoustic wave resonator described in any of the above.

[0380] <22>

[0381] according to <21> The surface acoustic wave filter, wherein,

[0382] The at least one parallel arm resonator includes the surface acoustic wave resonator.

[0383] The at least one series arm resonator does not include the surface acoustic wave resonator.

[0384] <23>

[0385] according to <21> The surface acoustic wave filter, wherein,

[0386] The at least one series arm resonator includes the surface acoustic wave resonator.

[0387] The at least one parallel arm resonator includes the surface acoustic wave resonator.

[0388] In the at least one series-arm resonator included in the surface acoustic wave resonator, the area of ​​the portion of the plurality of load members overlapping with the plurality of electrode fingers when viewed from above the substrate is smaller than the area of ​​the portion of the plurality of load members overlapping with the plurality of electrode fingers when viewed from above the substrate in the at least one parallel-arm resonator included in the surface acoustic wave resonator.

[0389] <24>

[0390] according to <21> The surface acoustic wave filter, wherein,

[0391] The at least one series arm resonator includes the surface acoustic wave resonator.

[0392] The at least one parallel arm resonator includes the surface acoustic wave resonator.

[0393] The number of electrode fingers overlapping with the plurality of load members in the surface acoustic wave resonator included in the at least one series arm resonator is less than the number of electrode fingers overlapping with the plurality of load members in the surface acoustic wave resonator included in the at least one parallel arm resonator.

[0394] <25>

[0395] according to <21> The surface acoustic wave filter, wherein,

[0396] The at least one series arm resonator includes the surface acoustic wave resonator.

[0397] The at least one parallel arm resonator includes the surface acoustic wave resonator.

[0398] The thickness of the plurality of load members of the surface acoustic wave resonator included in the at least one series arm resonator is smaller than the thickness of the plurality of load members of the surface acoustic wave resonator included in the at least one parallel arm resonator.

[0399] <26>

[0400] according to <21> The surface acoustic wave filter, wherein,

[0401] The at least one series arm resonator includes a first series arm resonator connected in series between the input terminal and the output terminal, and a second series arm resonator located further away from the input terminal than the first series arm resonator.

[0402] The first series arm resonator and the second series arm resonator are each of the surface acoustic wave resonators.

[0403] The number of electrode fingers overlapping with the plurality of load members in the first series arm resonator is less than the number of electrode fingers overlapping with the plurality of load members in the second series arm resonator.

[0404] <27>

[0405] according to <21> The surface acoustic wave filter, wherein,

[0406] The at least one parallel arm resonator comprises a plurality of parallel arm resonators connected in parallel between the path connecting the input terminal and the output terminal and ground.

[0407] The plurality of parallel arm resonators includes a first parallel arm resonator and a second parallel arm resonator that is further away from the input terminal than the first parallel arm resonator.

[0408] The first parallel arm resonator and the second parallel arm resonator are each of the surface acoustic wave resonators.

[0409] The number of electrode fingers overlapping with the plurality of load members in the first parallel arm resonator is less than the number of electrode fingers overlapping with the plurality of load members in the second parallel arm resonator.

[0410] <28>

[0411] according to <21> The surface acoustic wave filter, wherein,

[0412] At least two of the at least one series arm resonator and the at least one parallel arm resonator are surface acoustic wave resonators, arranged along the first axis on the substrate.

[0413] <29>

[0414] A multiplexer, comprising:

[0415] A transmit filter, connected between the antenna connection terminal and the PA connection terminal, has a passband that includes the transmit band of a given frequency band; and

[0416] A receiving filter, connected between the antenna connection terminal and the LNA connection terminal, has a passband that includes the receiving band of the given frequency band.

[0417] At least one of the transmitting filter and the receiving filter is <21> ~ <28> The surface acoustic wave filter described in any of the above.

[0418] <30>

[0419] according to <29> The multiplexer, wherein,

[0420] The receiving filter is the surface acoustic wave filter.

[0421] The transmitting filter is not the surface acoustic wave filter.

[0422] <31>

[0423] according to <29> The multiplexer, wherein,

[0424] The transmitting filter is the surface acoustic wave filter.

[0425] The at least one series arm resonator includes a plurality of series arm resonators connected in series between the antenna connection terminal and the PA connection terminal.

[0426] The series arm resonator closest to the antenna connection terminal among the plurality of series arm resonators is the surface acoustic wave resonator.

[0427] <32>

[0428] according to <29> The multiplexer, wherein,

[0429] The transmitting filter is the surface acoustic wave filter.

[0430] The at least one parallel arm resonator comprises a plurality of parallel arm resonators connected in parallel between the path connecting the antenna connection terminal and the PA connection terminal and ground.

[0431] The parallel arm resonator closest to the antenna connection terminal among the plurality of parallel arm resonators is the surface acoustic wave resonator.

[0432] <33>

[0433] according to <29> The multiplexer, wherein,

[0434] The receiving filter is the surface acoustic wave filter.

[0435] The at least one series arm resonator includes a plurality of series arm resonators connected in series between the antenna connection terminal and the LNA connection terminal.

[0436] The series arm resonator closest to the antenna connection terminal among the plurality of series arm resonators is the surface acoustic wave resonator.

[0437] <34>

[0438] according to <29> The multiplexer, wherein,

[0439] The receiving filter is the surface acoustic wave filter.

[0440] The at least one parallel arm resonator comprises a plurality of parallel arm resonators connected in parallel between the path connecting the antenna connection terminal and the LNA connection terminal and ground.

[0441] The parallel arm resonator closest to the antenna connection terminal among the plurality of parallel arm resonators is the surface acoustic wave resonator.

[0442] <35>

[0443] A surface acoustic wave resonator, comprising:

[0444] The substrate includes a piezoelectric layer;

[0445] At least one electrode, disposed on the substrate, includes an IDT electrode; and

[0446] A dielectric film is disposed on the at least one electrode.

[0447] The at least one electrode comprises: a plurality of electrode fingers arranged on the substrate along a first axis and extending respectively along a second axis perpendicular to the first axis.

[0448] The average thickness of the dielectric film disposed on the electrode fingers in the first sub-region and the average thickness of the dielectric film disposed on the electrode fingers in the third sub-region are both greater than the average thickness of the dielectric film disposed on the electrode fingers in the second sub-region.

[0449] The first sub-region, the second sub-region, and the third sub-region are obtained by equally dividing the area on the substrate where the plurality of electrode fingers are disposed in the direction of the second axis.

[0450] The second sub-region is located between the first sub-region and the third sub-region.

[0451] Industrial availability

[0452] This invention, as a surface acoustic wave device, can be widely used in communication devices such as portable telephones.

[0453] Explanation of reference numerals in the attached figures

[0454] 1: Surface acoustic wave resonator;

[0455] 3: Substrate;

[0456] 3a, 31a, 31b: Main face;

[0457] 3b: Electrode refers to the region;

[0458] 3b1: First subregion;

[0459] 3b2: Second subregion;

[0460] 3b3: The third subregion;

[0461] 4, 4C, 6: Electrodes;

[0462] 5, 5A: Dielectric film;

[0463] 31: Piezoelectric layer;

[0464] 32: Low-sound-velocity layer;

[0465] 33: Hypersonic layer;

[0466] 34: Support base plate;

[0467] 41, 61: IDT electrodes;

[0468] 42, 62: Reflective electrodes;

[0469] 51, 51A, 51B, 51C, 51D, 53a, 53b, 71: Load-bearing components;

[0470] 52: Protective film;

[0471] 100: Surface acoustic wave filter;

[0472] 101, 102, 103, 104: Series arm resonators;

[0473] 111, 112, 113, 114: Parallel arm resonators;

[0474] 121: Input terminal;

[0475] 122: Output terminal;

[0476] 123: Grounding terminal;

[0477] 200: Multiplexer;

[0478] 201, 203: Transmit filters;

[0479] 202, 204: Receiver filters;

[0480] 211: Antenna connection terminal;

[0481] 212, 214: PA connection terminals;

[0482] 213, 215: LNA connection terminals;

[0483] 411a, 411b, 421, 611a, 611b, 621: Electrode fingers;

[0484] 412a, 412b, 422a, 422b, 612a, 612b, 622a, 622b: Busbar electrodes.

Claims

1. A surface acoustic wave resonator, comprising: The substrate includes a piezoelectric layer; At least one first electrode is disposed on the substrate, including a first IDT electrode; and Multiple first load members, disposed separately on or within the substrate, are made of dielectric material. The at least one first electrode comprises: a plurality of first electrode fingers arranged on the substrate along a first axis and extending respectively along a second axis perpendicular to the first axis. Each of the plurality of first load members, when viewed from above on the substrate, at least partially overlaps with at least one corresponding first electrode finger. The number of first electrode fingers overlapping with the plurality of first load members in the first electrode fingers disposed in the first sub-region and the number of first electrode fingers overlapping with the plurality of first load members in the first electrode fingers disposed in the third sub-region are respectively greater than the number of first electrode fingers overlapping with the plurality of first load members in the first electrode fingers disposed in the second sub-region. The first sub-region, the second sub-region, and the third sub-region are obtained by equally dividing the area on the substrate where the plurality of first electrodes are disposed in the direction of the second axis. The second sub-region is located between the first sub-region and the third sub-region. The plurality of first load members include two or more first load members that overlap with the first electrode finger disposed in the first sub-region and two or more first load members that overlap with the first electrode finger disposed in the third sub-region.

2. The surface acoustic wave resonator according to claim 1, wherein, The at least one first electrode further includes a pair of first reflective electrodes. The first IDT electrode is disposed between the pair of first reflective electrodes.

3. The surface acoustic wave resonator according to claim 2, wherein, At least one of the plurality of first load members, when viewed from above on the substrate, at least partially overlaps with at least one corresponding first electrode finger of the first IDT electrode. At least one of the other first load members, when viewed from above the substrate, at least partially overlaps with at least one corresponding first electrode finger of the first reflective electrode.

4. The surface acoustic wave resonator according to any one of claims 1 to 3, wherein, The plurality of first load members correspond one-to-one with several of the plurality of first electrode fingers.

5. The surface acoustic wave resonator according to claim 4, wherein, Each of the plurality of first load members overlaps with a portion of a corresponding first electrode finger when viewed from above on the substrate.

6. The surface acoustic wave resonator according to claim 5, wherein, The midpoint of each of the plurality of first load members along the length of the first axis is offset along the first axis from the midpoint of the length of the corresponding first electrode along the first axis in the direction of the center of the first IDT electrode.

7. The surface acoustic wave resonator according to any one of claims 1 to 6, wherein, The plurality of first load members are a plurality of first load films disposed on the substrate. The plurality of first load films at least partially cover several of the plurality of first electrode fingers.

8. The surface acoustic wave resonator according to claim 7, wherein, In each of the plurality of first load films, the thickness of the first load film on the top surface of the corresponding at least one first electrode finger is greater than the thickness of the first load film on the side surface of the corresponding at least one first electrode finger.

9. The surface acoustic wave resonator according to claim 7 or 8, wherein, The surface acoustic wave resonator also features: A protective film is disposed on the substrate, covering the substrate and at least a portion of the plurality of first electrode fingers.

10. The surface acoustic wave resonator according to claim 9, wherein, The protective film is stacked on the plurality of first load films.

11. The surface acoustic wave resonator according to claim 9 or 10, wherein, The plurality of first load films are made of a different material than the protective film.

12. The surface acoustic wave resonator according to claim 11, wherein, The plurality of first loaded films comprise tantalum pentoxide, niobium pentoxide, tungsten oxide (VI), silicon nitride, titanium oxide (IV), cerium oxide (IV), hafnium oxide (IV), or ytterbium oxide (III). The protective film is made of silicon dioxide or silicon nitride.

13. The surface acoustic wave resonator according to any one of claims 1 to 6, wherein, The plurality of first load members are disposed within the substrate.

14. The surface acoustic wave resonator according to claim 13, wherein, The substrate further includes a low-velocity layer, wherein the velocity of sound of the propagating bulk wave is lower than the velocity of sound of the elastic wave propagating in the piezoelectric layer. The piezoelectric layer is disposed on the low-velocity layer. The plurality of first load members are disposed within the low-sound-velocity layer.

15. The surface acoustic wave resonator according to any one of claims 1 to 14, wherein, The interval between a first electrode finger that overlaps with the plurality of first load members and a first electrode finger that is adjacent to the first electrode finger but does not overlap with the plurality of first load members is different from the interval between two first electrode fingers that are adjacent to each other and overlap with the plurality of first load members or the interval between two first electrode fingers that are adjacent to each other and do not overlap with the plurality of first load members.

16. The surface acoustic wave resonator according to any one of claims 1 to 15, wherein, The duty cycle of two or more first electrode fingers that overlap with the plurality of first load members is different from the duty cycle of two or more first electrode fingers that do not overlap with any of the plurality of first load members.

17. The surface acoustic wave resonator according to any one of claims 1 to 16, wherein, The spacing between two or more first electrode fingers that overlap with the plurality of first load members is different from the spacing between two or more first electrode fingers that do not overlap with any of the plurality of first load members.

18. The surface acoustic wave resonator according to any one of claims 1 to 17, wherein, The width of at least one of two or more first electrode fingers that does not overlap with any of the plurality of first load members is different from the width of at least one of the other two or more first electrode fingers that does not overlap with any of the plurality of first load members.

19. The surface acoustic wave resonator according to any one of claims 1 to 18, wherein, The spacing of at least one group of adjacent first electrode fingers among two or more first electrode fingers that do not overlap with any of the plurality of first load members is different from the spacing of at least one other group of adjacent first electrode fingers among the two or more first electrode fingers that do not overlap with any of the plurality of first load members.

20. The surface acoustic wave resonator according to claim 19, wherein, The spacing of adjacent first electrode fingers in multiple groups of two or more first electrode fingers that do not overlap with any of the plurality of first load members is different from that of each other.

21. The surface acoustic wave resonator according to any one of claims 1 to 20, wherein, The surface acoustic wave resonator further comprises: a plurality of second load members, which, when viewed from above the substrate, at least partially overlap the front end of the first electrode finger of the first IDT electrode among the plurality of first electrode fingers.

22. The surface acoustic wave resonator according to claim 21, wherein, The plurality of first load members are a plurality of first load films disposed on the substrate. The plurality of second load members are made of the same material as the plurality of first load films and are disposed on the substrate.

23. The surface acoustic wave resonator according to claim 22, wherein, The thickness of the plurality of first load films is the same as the thickness of the plurality of second load films.

24. The surface acoustic wave resonator according to claim 22, wherein, The thickness of the plurality of first load films is greater than the thickness of the plurality of second load films.

25. The surface acoustic wave resonator according to any one of claims 1 to 24, wherein, The piezoelectric layer includes a first main surface and a second main surface that are opposite each other. The at least one first electrode is disposed on one of the first main surface and the second main surface. The surface acoustic wave resonator further comprises: at least one second electrode, disposed on the other of the first main surface and the second main surface, including a second IDT electrode. The at least one second electrode comprises: a plurality of second electrode fingers arranged on the substrate along a first axis and extending respectively along a second axis perpendicular to the first axis. The plurality of second electrode fingers overlap one-to-one with the plurality of first electrode fingers when viewed from above on the substrate.

26. The surface acoustic wave resonator according to claim 25, wherein, The surface acoustic wave resonator further comprises: a plurality of third load members, disposed separately on or within the substrate, and made of dielectric material. Each of the plurality of third load members, when viewed from above on the substrate, at least partially overlaps with at least one corresponding second electrode finger. The number of second electrode fingers overlapping with the plurality of third load members in the second electrode fingers disposed in the first sub-region and the number of second electrode fingers overlapping with the plurality of third load members in the second electrode fingers disposed in the third sub-region are respectively greater than the number of second electrode fingers overlapping with the plurality of third load members in the second electrode fingers disposed in the second sub-region. The plurality of third load members include two or more third load members that overlap with the second electrode finger disposed in the first sub-region and two or more third load members that overlap with the second electrode finger disposed in the third sub-region.

27. The surface acoustic wave resonator according to claim 25 or 26, wherein, The at least one second electrode further includes a pair of second reflective electrodes. The second IDT electrode is disposed between the pair of second reflective electrodes.

28. A surface acoustic wave filter, comprising: At least one series arm resonator; and At least one parallel arm resonator, At least one of the at least series arm resonator and at least one parallel arm resonator is a surface acoustic wave resonator according to any one of claims 1 to 27.

29. The surface acoustic wave filter according to claim 28, wherein, The at least one parallel arm resonator includes the surface acoustic wave resonator. The at least one series arm resonator does not include the surface acoustic wave resonator.

30. The surface acoustic wave filter according to claim 28, wherein, The at least one series arm resonator includes the surface acoustic wave resonator. The at least one parallel arm resonator includes the surface acoustic wave resonator. In the at least one series-arm resonator included in the surface acoustic wave resonator, the area of ​​the portion of the plurality of first load members overlapping with the plurality of electrode fingers when viewed from the top of the substrate is smaller than the area of ​​the portion of the plurality of first load members overlapping with the plurality of electrode fingers when viewed from the top of the substrate in the at least one parallel-arm resonator included in the surface acoustic wave resonator.

31. The surface acoustic wave filter according to claim 28, wherein, The at least one series arm resonator includes the surface acoustic wave resonator. The at least one parallel arm resonator includes the surface acoustic wave resonator. The number of electrode fingers overlapping with the plurality of first load members in the surface acoustic wave resonator included in the at least one series arm resonator is less than the number of electrode fingers overlapping with the plurality of first load members in the surface acoustic wave resonator included in the at least one parallel arm resonator.

32. The surface acoustic wave filter according to claim 28, wherein, The at least one series arm resonator includes the surface acoustic wave resonator. The at least one parallel arm resonator includes the surface acoustic wave resonator. The thickness of the plurality of first load members of the surface acoustic wave resonator included in the at least one series arm resonator is smaller than the thickness of the plurality of first load members of the surface acoustic wave resonator included in the at least one parallel arm resonator.

33. The surface acoustic wave filter according to claim 28, wherein, The at least one series arm resonator includes a first series arm resonator connected in series between the input terminal and the output terminal, and a second series arm resonator located further away from the input terminal than the first series arm resonator. The first series arm resonator and the second series arm resonator are each of the surface acoustic wave resonators. The number of electrode fingers overlapping with the plurality of first load members in the first series arm resonator is less than the number of electrode fingers overlapping with the plurality of first load members in the second series arm resonator.

34. The surface acoustic wave filter according to claim 28, wherein, The at least one parallel arm resonator comprises a plurality of parallel arm resonators connected in parallel between the path connecting the input terminal and the output terminal and ground. The plurality of parallel arm resonators includes a first parallel arm resonator and a second parallel arm resonator that is further away from the input terminal than the first parallel arm resonator. The first parallel arm resonator and the second parallel arm resonator are each of the surface acoustic wave resonators. The number of electrode fingers overlapping with the plurality of first load members in the first parallel arm resonator is less than the number of electrode fingers overlapping with the plurality of first load members in the second parallel arm resonator.

35. The surface acoustic wave filter according to claim 28, wherein, At least two of the at least one series arm resonator and the at least one parallel arm resonator are surface acoustic wave resonators, arranged along the first axis on the substrate.

36. A multiplexer, comprising: A transmit filter, connected between the antenna connection terminal and the PA connection terminal, has a passband that includes the transmit band of a given frequency band; and A receiving filter, connected between the antenna connection terminal and the LNA connection terminal, has a passband that includes the receiving band of the given frequency band. At least one of the transmitting filter and the receiving filter is a surface acoustic wave filter according to any one of claims 28 to 35.

37. The multiplexer according to claim 36, wherein, The receiving filter is the surface acoustic wave filter. The transmitting filter is not the surface acoustic wave filter.

38. The multiplexer according to claim 36, wherein, The transmitting filter is the surface acoustic wave filter. The at least one series arm resonator includes a plurality of series arm resonators connected in series between the antenna connection terminal and the PA connection terminal. The series arm resonator closest to the antenna connection terminal among the plurality of series arm resonators is the surface acoustic wave resonator.

39. The multiplexer according to claim 36, wherein, The transmitting filter is the surface acoustic wave filter. The at least one parallel arm resonator comprises a plurality of parallel arm resonators connected in parallel between the path connecting the antenna connection terminal and the PA connection terminal and ground. The parallel arm resonator closest to the antenna connection terminal among the plurality of parallel arm resonators is the surface acoustic wave resonator.

40. The multiplexer according to claim 36, wherein, The receiving filter is the surface acoustic wave filter. The at least one series arm resonator includes a plurality of series arm resonators connected in series between the antenna connection terminal and the LNA connection terminal. The series arm resonator closest to the antenna connection terminal among the plurality of series arm resonators is the surface acoustic wave resonator.

41. The multiplexer according to claim 36, wherein, The receiving filter is the surface acoustic wave filter. The at least one parallel arm resonator comprises a plurality of parallel arm resonators connected in parallel between the path connecting the antenna connection terminal and the LNA connection terminal and ground. The parallel arm resonator closest to the antenna connection terminal among the plurality of parallel arm resonators is the surface acoustic wave resonator.

42. A surface acoustic wave resonator, comprising: The substrate includes a piezoelectric layer; At least one electrode, disposed on the substrate, includes an IDT electrode; and A dielectric film is disposed on the at least one electrode. The at least one electrode comprises: a plurality of electrode fingers arranged on the substrate along a first axis and extending respectively along a second axis perpendicular to the first axis. The average thickness of the dielectric film disposed on the electrode fingers in the first sub-region and the average thickness of the dielectric film disposed on the electrode fingers in the third sub-region are both greater than the average thickness of the dielectric film disposed on the electrode fingers in the second sub-region. The first sub-region, the second sub-region, and the third sub-region are obtained by equally dividing the area on the substrate where the plurality of electrode fingers are disposed in the direction of the second axis. The second sub-region is located between the first sub-region and the third sub-region.

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