Elastic wave device

Abstract

The elastic wave device (10) comprises: a piezoelectric layer (4); a first comb electrode (7) having a first busbar (12) and a plurality of first electrode fingers (15); a second comb electrode (8) having a second busbar (13) and a plurality of second electrode fingers (16) interleaved with the plurality of first electrode fingers (15); and a third electrode (9) having a plurality of third electrode fingers (17) respectively arranged side by side with the first electrode fingers (15) and the second electrode fingers (16), and at least one third busbar (14) connecting the plurality of third electrode fingers (17) to each other, and the third electrode is connected to a potential different from that of the first comb electrode (7) and the second comb electrode (8). The first electrode fingers (15), the second electrode fingers (16) and the third electrode fingers (17) are arranged in a cycle starting from the first electrode fingers (15). The third busbar (14) is electrically insulated from the plurality of first electrode fingers (15). A through hole (4c) is provided in the portion of the piezoelectric layer (4) located between the intersection region (E) of the first electrode fingers (15) and the second electrode fingers (16) and between the first busbar (12) and between the first comb electrode (7) and the third electrode (9) in the orthogonal direction of the electrode fingers, thereby suppressing the generation of unwanted waves.

Description

Technical Field

[0001] This invention relates to elastic wave devices. Background Technology

[0002] Previously, elastic wave devices were widely used in filters for portable telephones, etc. In recent years, elastic wave devices as acoustic coupling type filters, as described in Patent Document 1, have been proposed. In this acoustic coupling type filter, an electrode connected to a potential different from the input and output potentials, such as a reference potential, is disposed between the electrode connected to the input potential and the electrode connected to the output potential. Based on this structure, a filter waveform can be formed even within a single acoustic coupling type filter. Therefore, by reducing the number of components, the filter device can be miniaturized.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-190656 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The inventors of this invention have discovered that, in an elastic wave device that serves as an acoustic coupling filter, miniaturization of the elastic wave device itself can be achieved by having electrodes connected to the input potential and electrodes connected to potentials different from the input and output potentials cross in a three-dimensional manner. Furthermore, at the portions where the electrodes cross in a three-dimensional manner, the electrodes are electrically insulated from each other by providing an insulating layer between them.

[0008] However, the inventors of this invention have discovered that in the above structure, ripple is generated in the frequency characteristics of the elastic wave device, and the filter characteristics may be degraded.

[0009] The purpose of this invention is to provide an elastic wave device capable of suppressing the degradation of filter characteristics.

[0010] Methods for solving problems

[0011] In a broad embodiment of the elastic wave device according to the present invention, it comprises: a piezoelectric layer having a first main surface and a second main surface opposite to each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers connected at one end to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, the plurality of second electrode fingers interleaved with the plurality of first electrode fingers; and a third electrode having a plurality of third electrode fingers and at least one third busbar, the plurality of third electrode fingers being disposed on one of the first main surface and the second main surface of the piezoelectric layer such that, when viewed from above, they are arranged side by side with the first electrode fingers and the second electrode fingers in the direction in which the first electrode fingers and the second electrode fingers are arranged, the at least one third busbar connecting the plurality of third electrode fingers to each other, and the third electrode being connected to a potential different from that of the first comb-shaped electrode and the second comb-shaped electrode. One of the second comb electrodes is connected to the input potential, and the other of the first and second comb electrodes is connected to the output potential. The order of the first, second, and third electrode fingers is such that, starting from the first electrode finger, the first, second, and third electrode fingers are arranged as a cycle. When the direction orthogonal to the extension direction of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the area where the first and second electrode fingers overlap in the electrode finger orthogonal direction is a cross region. In top view, a third bus bar is located between the cross region and the first bus bar. The third bus bar overlaps with the plurality of first electrode fingers in top view and is electrically insulated from the plurality of first electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the first bus bar and located between the first comb electrode and the third electrode in the electrode finger orthogonal direction is provided with a through hole.

[0012] In another broad embodiment of the elastic wave device involved in this invention, it comprises: a piezoelectric layer having a first main surface and a second main surface opposite to each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers, one end of which is respectively connected to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers, one end of which is respectively connected to the second busbar, the plurality of second electrode fingers interleaved with the plurality of first electrode fingers; and a third electrode having a plurality of third electrode fingers and at least one third busbar, the plurality of third electrode fingers being disposed on one of the first main surface and the second main surface of the piezoelectric layer such that, when viewed from above, they are arranged side by side with the first electrode fingers and the second electrode fingers in the direction in which the first electrode fingers and the second electrode fingers are arranged, the at least one third busbar connecting the plurality of third electrode fingers to each other, and the third electrode being connected to a potential different from that of the first comb-shaped electrode and the second comb-shaped electrode. One of the second comb-shaped electrodes is connected to the input potential, and the other of the first and second comb-shaped electrodes is connected to the output potential. The order of the first, second, and third electrode fingers is such that, starting from the first electrode finger, the first, second, and third electrode fingers are arranged in a cycle. When the direction orthogonal to the extension direction of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the area where the first and second electrode fingers overlap in the electrode finger orthogonal direction is a cross region. In top view, the first busbar is located between the cross region and one of the third busbars. The first busbar overlaps with the plurality of third electrode fingers in top view. The first busbar is electrically insulated from the plurality of third electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the first busbar and located between the first comb-shaped electrode and the third electrode in the electrode finger orthogonal direction is provided with a through hole.

[0013] In another broad embodiment of the elastic wave device according to the present invention, it comprises: a piezoelectric layer having a first main surface and a second main surface opposite to each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers with one end respectively connected to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers with one end respectively connected to the second busbar, the plurality of second electrode fingers interleaving with the plurality of first electrode fingers; and a third electrode... The piezoelectric element has multiple third electrode fingers, multiple connecting electrodes, and at least one third busbar. The multiple third electrode fingers are respectively disposed on the first main surface of the piezoelectric layer, such that, when viewed from above, they are arranged side-by-side with the first and second electrode fingers in the direction in which the first and second electrode fingers are arranged. The multiple connecting electrodes penetrate the piezoelectric layer and are respectively connected to the multiple third electrode fingers. The at least one third busbar is disposed on the second main surface and is electrically connected to the multiple third electrode fingers through the multiple connecting electrodes. Furthermore, the third electrode bar is connected to different... The first comb electrode and the second comb electrode are connected at potentials. One of the first comb electrode and the second comb electrode is connected to the input potential, and the other of the first comb electrode and the second comb electrode is connected to the output potential. The first electrode finger, the second electrode finger, and the third electrode finger are arranged in a cycle starting from the first electrode finger. When the direction orthogonal to the extension direction of the first electrode finger, the second electrode finger, and the third electrode finger are defined as the electrode finger orthogonal direction, the area where the first electrode finger and the second electrode finger overlap in the electrode finger orthogonal direction is the intersection area. In top view, a third bus bar is located between the intersection area and the first bus bar. The third bus bar overlaps with the plurality of first electrode fingers in top view. At least a portion of the portion of the piezoelectric layer located between the intersection area and the first bus bar and located between the first electrode finger and the third electrode finger in the electrode finger orthogonal direction is provided with a through hole.

[0014] In another broad embodiment of the elastic wave device involved in this invention, it comprises: a piezoelectric layer having a first main surface and a second main surface facing each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers connected at one end to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, the plurality of second electrode fingers interleaved with the plurality of first electrode fingers; and a third electrode having a plurality of third electrode fingers disposed on the first main surface of the piezoelectric layer such that, when viewed from above, they are arranged side by side with the first electrode fingers and the second electrode fingers in the direction in which the first electrode fingers and the second electrode fingers are arranged, the third electrode having a plurality of connecting electrodes connected to the plurality of third electrode fingers respectively, and a third busbar electrically connected to the plurality of third electrode fingers through the plurality of connecting electrodes, and the third electrode having a connection bar different from the first comb-shaped electrode and the second comb-shaped electrode. The potential connection of the electrodes is as follows: one of the first comb electrode and the second comb electrode is connected to the input potential, and the other of the first comb electrode and the second comb electrode is connected to the output potential. The order of the first electrode finger, the second electrode finger, and the third electrode finger is the order of the first electrode finger, the second electrode finger, and the third electrode finger as a cycle, starting from the first electrode finger. When the direction orthogonal to the extension direction of the first electrode finger, the second electrode finger, and the third electrode finger is defined as the electrode finger orthogonal direction, the area where the first electrode finger and the second electrode finger overlap in the electrode finger orthogonal direction is the intersection area. In top view, a third bus bar is located between the intersection area and the first bus bar. The third bus bar overlaps with the plurality of first electrode fingers in top view. At least a portion of the portion of the piezoelectric layer located between the intersection area and the first bus bar and located between the first electrode finger and the third electrode finger in the electrode finger orthogonal direction is provided with a through hole.

[0015] Invention Effects

[0016] The elastic wave device according to the present invention can suppress the degradation of filter characteristics. Attached Figure Description

[0017] Figure 1 This is a schematic front cross-sectional view of the elastic wave device according to the first embodiment of the present invention.

[0018] Figure 2 This is a schematic top view of the elastic wave device according to the first embodiment of the present invention.

[0019] Figure 3 It is along Figure 2 A schematic cross-sectional view of line II-II in the diagram.

[0020] Figure 4 This is a schematic top view of a comparative example elastic wave device.

[0021] Figure 5 This is a graph showing the throughput characteristics in the comparative example.

[0022] Figure 6 This is a diagram illustrating the passage characteristics in the first embodiment of the present invention.

[0023] Figure 7 This is a schematic top view of an elastic wave device according to a first variation of the first embodiment of the present invention.

[0024] Figure 8 This is a schematic top view of an elastic wave device according to a second variation of the first embodiment of the present invention.

[0025] Figure 9 This is a schematic top view of the elastic wave device according to the second embodiment of the present invention.

[0026] Figure 10 This is a schematic front cross-sectional view showing a first electrode finger and a third bus bar near the portion where they intersect across the insulating layer in a modified example of the second embodiment of the present invention.

[0027] Figure 11 This is a schematic top view of the elastic wave device according to the third embodiment of the present invention.

[0028] Figure 12 This is a schematic top view of the elastic wave device according to the fourth embodiment of the present invention.

[0029] Figure 13 This is a schematic top view of the elastic wave device according to the fifth embodiment of the present invention.

[0030] Figure 14 This is a schematic top view of the elastic wave device according to the sixth embodiment of the present invention.

[0031] Figure 15 This is a schematic top view of an elastic wave device according to a variation of the sixth embodiment of the present invention.

[0032] Figure 16 This is a schematic top view showing a portion of the elastic wave device according to the seventh embodiment of the present invention.

[0033] Figure 17 It is along Figure 16A schematic cross-sectional view of line III-III in the diagram.

[0034] Figure 18 This is a diagram illustrating the passage characteristics in the seventh embodiment of the present invention.

[0035] Figure 19 This is a schematic top view of the elastic wave device according to the eighth embodiment of the present invention.

[0036] Figure 20 This is a schematic top view of the elastic wave device according to the ninth embodiment of the present invention.

[0037] Figure 21 This is a schematic top view of the elastic wave device according to the tenth embodiment of the present invention.

[0038] Figure 22 It is along Figure 21 A schematic cross-sectional view of line IV-IV in the diagram.

[0039] Figure 23 This is a schematic top view of the elastic wave device according to the eleventh embodiment of the present invention.

[0040] Figure 24 It is along Figure 23 A schematic cross-sectional view of line II in the diagram.

[0041] Figure 25 It is along Figure 23 A schematic cross-sectional view of the VV line.

[0042] Figure 26 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the first variation of the eleventh embodiment of the present invention.

[0043] Figure 27 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the second variation of the eleventh embodiment of the present invention.

[0044] Figure 28 This is a simplified front sectional view of the elastic wave device according to the twelfth embodiment of the present invention.

[0045] Figure 29 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the twelfth embodiment of the present invention.

[0046] Figure 30 This is a schematic top view showing the electrode structure on the first main surface of the piezoelectric layer in the twelfth embodiment of the present invention.

[0047] Figure 31This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the first variation of the twelfth embodiment of the present invention.

[0048] Figure 32 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the second variation of the twelfth embodiment of the present invention.

[0049] Figure 33 This is a simplified front sectional view of the elastic wave device according to the thirteenth embodiment of the present invention.

[0050] Figure 34 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the thirteenth embodiment of the present invention.

[0051] Figure 35 This is a schematic top view showing the electrode structure on the first main surface of the piezoelectric layer in the thirteenth embodiment of the present invention.

[0052] Figure 36 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the first variation of the thirteenth embodiment of the present invention.

[0053] Figure 37 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the second variation of the thirteenth embodiment of the present invention.

[0054] Figure 38 This is a schematic front cross-sectional view of the elastic wave device according to the fourteenth embodiment of the present invention.

[0055] Figure 39 This is a schematic top view of a reference example elastic wave device.

[0056] Figure 40 This is a graph showing the relationship between d / p and the fractional bandwidth of the elastic wave device in the reference example.

[0057] Figure 41 This is a graph showing the relationship between the fractional bandwidth and the normalized spurious magnitude in the elastic wave device of the reference example.

[0058] Figure 42 This is a graph showing the relationship between d / p, metallization rate (MR), and fractional bandwidth.

[0059] Figure 43 This is a graph showing the mapping of the fractional bandwidth relative to the Euler angles (0°, θ, ψ) of LiNbO3 when d / p is infinitely close to 0. Detailed Implementation

[0060] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings, thereby making the present invention clear.

[0061] Furthermore, the embodiments described in this specification are illustrative, indicating in advance that partial substitutions or combinations of structures can be made between different embodiments.

[0062] Figure 1 This is a schematic front cross-sectional view of the elastic wave device according to the first embodiment of the present invention. Figure 2 This is a schematic top view of the elastic wave device according to the first embodiment. Additionally, Figure 1 It is along Figure 2 A schematic cross-sectional view of line II in the diagram. Figure 2 In the diagram, each electrode in the piezoelectric layer, described later, is indicated by shading. Conversely, the through-holes in the piezoelectric layer, described later, are indicated by intersecting shading. Figure 2 In the diagram, the connection between the third electrode (described later) and the reference potential is schematically shown using the notation for the reference potential. Figure 2 In schematic top views other than those shown, electrodes are sometimes also marked with shaded lines, through holes with cross-shading lines, and reference potential symbols are used.

[0063] Figure 1 The elastic wave device 10 shown is configured to utilize a volume wave with a thickness shear mode. The elastic wave device 10 is an acoustic coupling type filter. The structure of the elastic wave device 10 will be described below.

[0064] The elastic wave device 10 includes a piezoelectric substrate 2 and a functional electrode 1. The piezoelectric substrate 2 is a substrate with piezoelectric properties. Specifically, the piezoelectric substrate 2 includes a support member 3 and a piezoelectric layer 4. In this embodiment, the support member 3 includes a support substrate 6 and an insulating layer 5. The insulating layer 5 is provided on the support substrate 6. The piezoelectric layer 4 is provided on the insulating layer 5. Not limited to the above, the support member 3 may also be composed solely of the support substrate 6. Alternatively, the support member 3 may not be necessary.

[0065] The piezoelectric layer 4 has a first main surface 4a and a second main surface 4b. The first main surface 4a and the second main surface 4b are opposite to each other. The second main surface 4b is located on the side of the support member 3. A functional electrode 1 is provided on the first main surface 4a of the piezoelectric layer 4. In this specification, "provided on the first main surface 4a" includes both the case where it is directly provided on the first main surface 4a and the case where it is indirectly provided on the first main surface 4a through other members. In this embodiment, the functional electrode 1 is directly provided on the first main surface 4a.

[0066] Additionally, in the piezoelectric layer 4, from the first main surface 4a to the second main surface 4b, there are... Figure 2The through-hole 4c is shown. In this embodiment, the through-hole 4c is not provided in the portion of the piezoelectric layer 4 where the functional electrode 1 is provided. Therefore, any portion of the functional electrode 1 is provided on the piezoelectric layer 4.

[0067] like Figure 2 As shown, the functional electrode 1 has a pair of comb-shaped electrodes and a third electrode 9. Specifically, the pair of comb-shaped electrodes are a first comb-shaped electrode 7 and a second comb-shaped electrode 8. The first comb-shaped electrode 7 is connected to the input potential. The second comb-shaped electrode 8 is connected to the output potential. In this embodiment, the third electrode 9 is connected to a reference potential. Therefore, in this embodiment, the third electrode 9 is a reference potential electrode.

[0068] Alternatively, the first comb electrode 7 can also be connected to the output potential. The second comb electrode 8 can also be connected to the input potential. Thus, the first comb electrode 7 can be connected to one of the input and output potentials, and the second comb electrode 8 can be connected to the other of the input and output potentials. This structure can also be applied to structures of the present invention other than those in the first embodiment.

[0069] The third electrode 9 does not necessarily need to be connected to the reference potential. The third electrode 9 can be connected to a potential different from that of the first comb electrode 7 and the second comb electrode 8. However, it is preferable that the third electrode 9 is connected to the reference potential.

[0070] The first comb-shaped electrode 7 and the second comb-shaped electrode 8 are disposed on the first main surface 4a of the piezoelectric layer 4. More specifically, the first comb-shaped electrode 7 and the second comb-shaped electrode 8 are directly disposed on the first main surface 4a. The first comb-shaped electrode 7 has a first busbar 12 and a plurality of first electrode fingers 15. One end of each of the plurality of first electrode fingers 15 is connected to the first busbar 12. On the other hand, the second comb-shaped electrode 8 has a second busbar 13 and a plurality of second electrode fingers 16. One end of each of the plurality of second electrode fingers 16 is connected to the second busbar 13.

[0071] The first busbar 12 and the second busbar 13 are opposite to each other. A plurality of first electrode fingers 15 and a plurality of second electrode fingers 16 are interleaved and interlocked. The first electrode fingers 15 and the second electrode fingers 16 are arranged alternately in a direction orthogonal to the direction in which they extend.

[0072] The third electrode 9 has a third busbar 14 and a plurality of third electrode fingers 17. In this embodiment, the plurality of third electrode fingers 17 and the third busbar 14 are disposed on the first main surface 4a of the piezoelectric layer 4. More specifically, the plurality of third electrode fingers 17 are directly disposed on the first main surface 4a. The third busbar 14, except for a portion thereof, is directly disposed on the first main surface 4a. The plurality of third electrode fingers 17 are electrically connected to each other through the third busbar 14.

[0073] More specifically, the third busbar 14 includes multiple common connection portions 14a and bar portions 14b. Each adjacent pair of third electrode fingers 17 is connected to each other through the common connection portions 14a. Bar portions 14b are provided throughout the multiple common connection portions 14a. Alternatively, the third busbar 14 may not include the multiple common connection portions 14a.

[0074] The plurality of third electrode fingers 17 are respectively configured to be arranged side by side with the first electrode fingers 15 and the second electrode fingers 16 in the direction in which the first electrode fingers 15 and the second electrode fingers 16 are arranged when viewed from above. Therefore, the first electrode fingers 15, the second electrode fingers 16, and the third electrode fingers 17 are arranged in one direction. The plurality of third electrode fingers 17 extend parallel to the plurality of first electrode fingers 15 and the plurality of second electrode fingers 16.

[0075] In this specification, top view means from the perspective of... Figure 1 The view is taken from the upper direction along the stacking direction of the support member 3 and the piezoelectric layer 4. Additionally, in Figure 1 In this context, for example, the piezoelectric layer 4 side is considered the upper side, specifically the side of the support substrate 6 and the side of the piezoelectric layer 4. Furthermore, in this specification, a top view and a view from the main face orientation are synonymous. The main face orientation is the direction in which the first main surface 4a and the second main surface 4b of the piezoelectric layer 4 are opposite each other. More specifically, the main face orientation is, for example, the normal direction of the first main surface 4a.

[0076] Hereinafter, the extending directions of the first electrode finger 15, the second electrode finger 16, and the third electrode finger 17 will be defined as the electrode finger extending direction, and the direction orthogonal to the electrode finger extending direction will be defined as the electrode finger orthogonal direction. In this embodiment, the electrode finger orthogonal direction is parallel to the extending directions of the first bus bar 12, the second bus bar 13, and the third bus bar 14. In this specification, the first electrode finger 15, the second electrode finger 16, and the third electrode finger 17 are sometimes collectively referred to as electrode fingers. The first bus bar 12, the second bus bar 13, and the third bus bar 14 are sometimes collectively referred to as bus bars.

[0077] The order of the multiple electrode fingers is as follows: starting with the first electrode finger 15, the sequence is: first electrode finger 15, third electrode finger 17, second electrode finger 16, and third electrode finger 17 as a cycle. Therefore, the order of the multiple electrode fingers continues as follows: first electrode finger 15, third electrode finger 17, second electrode finger 16, third electrode finger 17, first electrode finger 15, third electrode finger 17, second electrode finger 16… If IN represents the input potential, OUT represents the output potential, and GND represents the reference potential, and the order of the multiple electrode fingers is represented by the order of the connected potentials, then it continues as IN, GND, OUT, GND, IN, GND, OUT…

[0078] exist Figure 2 In the embodiment shown, in the region where multiple electrode fingers are provided, the electrode fingers at both ends in the orthogonal direction of the electrode fingers are both second electrode fingers 16. Alternatively, in this region, the electrode fingers at the ends in the orthogonal direction of the electrode fingers can be any type of electrode finger among the first electrode finger 15, the second electrode finger 16, and the third electrode finger 17.

[0079] In functional electrode 1, the structure, except for the third electrode 9, is the same as that of the IDT (Interdigital Transducer) electrode. When viewed from the orthogonal direction of the electrode fingers, the overlapping area between adjacent first electrode fingers 15 and second electrode fingers 16 is the intersection region E. However, the intersection region E can also be described as the area where adjacent first electrode fingers 15 and third electrode fingers 17, or adjacent second electrode fingers 16 and third electrode fingers 17, overlap when viewed from the orthogonal direction of the electrode fingers.

[0080] like Figure 2 As shown, the third busbar 14 of the third electrode 9 electrically connects multiple third electrode fingers 17 to each other. Specifically, the third busbar 14 is located in the region between the intersection region E and the first busbar 12. Multiple first electrode fingers 15 are also located in this region. However, the third busbar 14 and the multiple first electrode fingers 15 are electrically insulated from each other by multiple insulating layers 19.

[0081] Figure 3 It is along Figure 2 A schematic cross-sectional view of line II-II in the diagram.

[0082] An insulating layer 19 is configured to cover the first electrode finger 15 on the first main surface 4a of the piezoelectric layer 4. More specifically, in this embodiment, an insulating layer 19 covers a portion of the electrode finger extension direction of a first electrode finger 15.

[0083] More specifically, such as Figure 2 As shown, multiple insulating layers 19 are arranged along the orthogonal direction of the electrode fingers. Each insulating layer 19 is configured to cover a portion of a first electrode finger 15. On the other hand, the common connection portion 14a is not covered by the insulating layers 19. On the first main surface 4a, strip portions 14b are provided throughout the multiple insulating layers 19 and the multiple common connection portions 14a.

[0084] Thus, the plurality of first electrode fingers 15, which are part of the first comb electrode 7, intersect with the third busbar 14, which is part of the third electrode 9, on the piezoelectric layer 4, separated by an insulating layer 19. In other words, the third busbar 14 and the plurality of first electrode fingers 15 are three-dimensionally intersected by the insulating layer 19. As a result, the third busbar 14 and the plurality of first electrode fingers 15 are electrically insulated from each other. On the other hand, the third busbar 14 electrically connects the plurality of third electrode fingers 17.

[0085] In this embodiment, the first electrode finger 15, the second electrode finger 16, and the third electrode finger 17 comprise stacked metal films. Specifically, in each electrode finger, a Ti layer, an Al layer, and a Ti layer are sequentially stacked from the piezoelectric layer 4 side. Furthermore, the material of each electrode finger is not limited to the above. Alternatively, each electrode finger may also comprise a single-layer metal film.

[0086] In this embodiment, the third busbar 14 is located in the region between the intersection region E and the first busbar 12. In other words, the third busbar 14 is located in the region between the tips of the plurality of second electrode fingers 16 and the first busbar 12. Therefore, the tips of the plurality of second electrode fingers 16 are spaced apart in the electrode finger extension direction and face the third busbar 14. On the other hand, the tips of the plurality of first electrode fingers 15 are spaced apart in the electrode finger extension direction and face the second busbar 13.

[0087] Alternatively, the third busbar 14 may be located in the region between the tips of the plurality of first electrode fingers 15 and the second busbar 13. In this case, the tips of the plurality of first electrode fingers 15 are spaced apart and opposite the third busbar 14. On the other hand, the tips of the plurality of second electrode fingers 16 are spaced apart and opposite the first busbar 12.

[0088] like Figure 2 As shown, through holes 4c are provided in the piezoelectric layer 4. Specifically, multiple through holes 4c are provided in the portion of the piezoelectric layer 4 between the intersection region E and the first busbar 12. The multiple through holes 4c are provided in both the side of the piezoelectric layer 4 closest to the intersection region E and the side closest to the first busbar 12, which is closer to the strip portion 14b of the third busbar 14. However, the through holes 4c are not provided between the imaginary line connecting the end edge of the multiple common connecting portions 14a in the third busbar 14 at the intersection region E and the intersection region E.

[0089] A portion of all the through holes 4c are located in the piezoelectric layer 4, between the strip portion 14b of the third busbar 14 and the intersection region E, and also between the plurality of first electrode fingers 15 and the plurality of common connection portions 14a in the third busbar 14. The remaining through holes 4c are located in the piezoelectric layer 4, between the strip portion 14b and the first busbar 12, and also between the plurality of first electrode fingers 15 and the plurality of common connection portions 14a, as well as between the plurality of first electrode fingers 15 and each other.

[0090] The elastic wave device 10 is an elastic wave resonator configured to utilize volume waves in a thickness shear mode. For example... Figure 2 As shown, the elastic wave device 10 has multiple excitation regions C. Elastic waves are excited in the multiple excitation regions C. Furthermore, in... Figure 2 In the diagram, only two of the multiple excitation regions C are shown.

[0091] A portion of the excitation regions C are areas where adjacent first electrode fingers 15 and third electrode fingers 17 overlap when viewed from the orthogonal direction of the electrode fingers, and are located between the centers of adjacent first electrode fingers 15 and third electrode fingers 17. The remaining excitation regions C are areas where adjacent second electrode fingers 16 and third electrode fingers 17 overlap when viewed from the orthogonal direction of the electrode fingers, and are located between the centers of adjacent second electrode fingers 16 and third electrode fingers 17. These excitation regions C are arranged in the orthogonal direction of the electrode fingers. Multiple excitation regions C are included in the aforementioned cross region E. Furthermore, the cross region E and the excitation regions C are regions of the piezoelectric layer 4 defined based on the structure of the functional electrode 1.

[0092] The elastic wave device 10 is an acoustic coupling type filter. Multiple modes of elastic waves, including a thickness shear mode, are excited in excitation regions C located between the centers of adjacent first electrode fingers 15 and third electrode fingers 17, and between the centers of adjacent second electrode fingers 16 and third electrode fingers 17. By combining these modes, a suitable filter waveform can be obtained even within a single elastic wave device 10.

[0093] This embodiment is characterized in that at least a portion of the piezoelectric layer 4 located between the cross region E and the first busbar 12, and located between the first comb electrode 7 and the third electrode 9 in the electrode orthogonal direction, is provided with a through-hole 4c. This suppresses ripple in the frequency response and inhibits the degradation of filter characteristics. The details are illustrated below by comparing this embodiment with a comparative example.

[0094] like Figure 4As shown, the comparative example differs from the first embodiment in that the piezoelectric layer 204 does not have through holes.

[0095] In the first embodiment and the comparative example, the transmission characteristics were compared. The design parameters of the elastic wave device 10 having the structure of the first embodiment are as follows. In addition, the design parameters of the comparative example are also set to be the same as those of the first embodiment.

[0096] Piezoelectric layer: Material…LiNbO3, Euler angles (φ, θ, ψ)…(0°, 0°, 90°), thickness…400nm

[0097] The first electrode refers to the third electrode; the layer structure is as follows: from the piezoelectric layer side, Ti layer / Al layer / Ti layer, thickness is as follows: 10nm / 390nm / 4nm from the piezoelectric layer side.

[0098] The center-to-center distance between the first and third electrode fingers: 1.4 μm

[0099] The center-to-center distance between the second and third electrode fingers: 1.4 μm

[0100] Duty cycle: 0.3

[0101] Figure 5 This is a graph showing the throughput characteristics in the comparative example. Figure 6 This is a diagram illustrating the passage characteristics in the first embodiment. Figure 5 and Figure 6 The results obtained through FEM (Finite Element Method) simulation are shown. The characteristics are represented by S-parameters.

[0102] like Figure 5 As indicated by arrows A in the diagram, in the frequency response characteristic of the comparative example, a large ripple is generated within the passband. This ripple originates from unwanted waves. In contrast, as shown by... Figure 6 As shown, ripple is suppressed in the throughput characteristics of the first embodiment. Thus, in the first embodiment, it is possible to suppress the degradation of the filter characteristics. The reason for this will be explained below.

[0103] like Figure 2 As shown, in the first embodiment, the common connection portion 14a in the third busbar 14 is adjacent to the first electrode finger 15 in the orthogonal direction of the electrode fingers. Therefore, the common connection portion 14a and the first electrode finger 15 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. This is in Figure 4 The same applies to the comparative examples shown.

[0104] Furthermore, in the comparative example, electrodes located outside the cross region E, adjacent in the orthogonal direction of the electrodes, and connected to different potentials are all disposed on the piezoelectric layer 204, which is situated between these electrodes. In this case, unwanted waves are generated, and the filter characteristics deteriorate.

[0105] In contrast, Figure 2 In the first embodiment shown, a through-hole 4c is provided in the piezoelectric layer 4 between the plurality of common connection portions 14a of the third busbar 14 and the plurality of first electrode fingers 15. Therefore, the piezoelectric layer 4 is not located in these portions. This makes it difficult to generate unwanted waves. Consequently, it is possible to suppress the degradation of filter characteristics.

[0106] Furthermore, at least a portion of the piezoelectric layer 4 located between the cross region E and the first busbar 12, and between the first comb electrode 7 and the third electrode 9 in the orthogonal direction of the electrode fingers, may be provided with through holes 4c. For example, at least a portion of the portion between the plurality of common connection portions 14a of the third busbar 14 and the plurality of first electrode fingers 15 may be provided with through holes 4c. In this case, similar to the first embodiment, unwanted waves can be suppressed, and the degradation of filter characteristics can be suppressed.

[0107] The following describes further details of the structure of the first embodiment.

[0108] like Figure 1 As shown, a recess is provided in the insulating layer 5. A piezoelectric layer 4 is provided on the insulating layer 5 to block the recess. This forms a hollow portion. This hollow portion is a cavity 10a. In the first embodiment, the support member 3 and the piezoelectric layer 4 are configured such that a portion of the support member 3 and a portion of the piezoelectric layer 4 sandwich the cavity 10a and face each other. However, it is also possible that the recess in the support member 3 extends throughout the insulating layer 5 and the support substrate 6. Alternatively, it is also possible that only the recess provided in the support substrate 6 is blocked by the insulating layer 5. The recess may also be provided in the piezoelectric layer 4, for example. In addition, the cavity 10a may also be a through hole provided in the support member 3.

[0109] In the first embodiment, the cavity 10a does not overlap with the first busbar 12, the second busbar 13, and the third busbar 14 when viewed from above. Therefore, the first busbar 12, the second busbar 13, and the third busbar 14 are supported by the support member 3 and the piezoelectric layer 4.

[0110] The cavity 10a is the acoustic reflection part in this invention. The acoustic reflection part effectively encapsulates the energy of the elastic wave into the piezoelectric layer 4. The acoustic reflection part is positioned in the support member 3, in plan view, at least a portion of which overlaps with the functional electrode 1. More specifically, in plan view, at least a portion of each of the first electrode finger 15, the second electrode finger 16, and the third electrode finger 17 overlaps with the acoustic reflection part. Preferably, in plan view, multiple excitation regions C overlap with the acoustic reflection part.

[0111] Alternatively, the sound-reflecting part can also be a sound-reflecting membrane such as a multilayer sound-reflecting membrane, as described later. For example, a sound-reflecting membrane can also be provided on the surface of the supporting member.

[0112] In the first embodiment, the center-to-center distance between multiple pairs of adjacent first electrode fingers 15 and third electrode fingers 17 is the same as the center-to-center distance between multiple pairs of adjacent second electrode fingers 16 and third electrode fingers 17. However, the center-to-center distances between adjacent first electrode fingers 15 and third electrode fingers 17, and between adjacent second electrode fingers 16 and third electrode fingers 17, may not be fixed. In this case, the longest distance among the center-to-center distances between adjacent first electrode fingers 15 and third electrode fingers 17, and between adjacent second electrode fingers 16 and third electrode fingers 17, is set as p. Furthermore, as in this embodiment, when the center-to-center distance is fixed, the center-to-center distance between any two adjacent electrode fingers is always p.

[0113] When the thickness of the piezoelectric layer 4 is set to d, it is preferable that d / p is 0.5 or less, and more preferably d / p is 0.24 or less. This allows for the appropriate excitation of bulk waves in the thickness shear mode.

[0114] However, the elastic wave device of the present invention does not necessarily have to be configured as a volume wave capable of utilizing a thickness shear mode. For example, the elastic wave device of the present invention can also be configured to excite a plate wave. In this case, the excitation region is Figure 2 The intersection region E is shown.

[0115] In the first embodiment, an example is shown in which a through hole 4c is provided in the piezoelectric layer 4. Hereinafter, a first modification and a second modification of the first embodiment are shown, which differ from the first embodiment only in the position of the through hole 4c.

[0116] exist Figure 7 In the first modified example shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4A that does not overlap with the plurality of first electrode fingers 15 when viewed from above but overlaps with the third busbar 14. Furthermore, a plurality of through holes 4c are also provided between the plurality of common connecting portions 14a of the third busbar 14 in the piezoelectric layer 4A and the plurality of first electrode fingers 15. These through holes 4c reach the support member 3. Therefore, a portion of the third busbar 14 is supported by the support member 3.

[0117] On the other hand, in this modified example, the through hole 4c is not provided between the imaginary line connecting the multiple common connection portions 14a in the third busbar 14 and the first busbar 12. Furthermore, the first main surface 4a of each insulating layer 19 in the piezoelectric layer 4 is configured to cover each first electrode finger 15.

[0118] In this modified example and the first embodiment, the portion of the third busbar 14 other than the portion overlapping with the first electrode finger 15 in top view is adjacent to the first electrode finger 15 in the orthogonal direction of the electrode fingers. Therefore, the aforementioned portion of the third busbar 14 and the first electrode finger 15 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. In this modified example, the third busbar 14, located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials, is not directly disposed on the first main surface 4a of the piezoelectric layer 4A. Specifically, a portion of the third busbar 14 is supported by the support member 3, and the remaining portion is indirectly disposed on the first main surface 4a through the insulating layer 19. As a result, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0119] exist Figure 8 In the second modified example shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4B located between the cross region E and the first busbar 12 and which does not overlap with the first electrode finger 15 and the third electrode finger 17 when viewed from above.

[0120] Specifically, a plurality of through holes 4c are provided in the piezoelectric layer 4B located between the intersection region E and the third busbar 14, and between the plurality of first electrode fingers 15 and the plurality of third electrode fingers 17. A plurality of through holes 4c are also provided in the portion of the piezoelectric layer 4B that does not overlap with the plurality of first electrode fingers 15 but overlaps with the third busbar 14 when viewed from above. Furthermore, a plurality of through holes 4c are also provided between the plurality of common connection portions 14a of the third busbar 14 and the plurality of first electrode fingers 15 in the piezoelectric layer 4B. Additionally, a plurality of through holes 4c are also provided in the portion of the piezoelectric layer 4B located between the third busbar 14 and the first busbar 12, and between the plurality of first electrode fingers 15.

[0121] These through holes 4c reach the support member 3. Therefore, a portion of the third busbar 14 is supported by the support member 3. On the other hand, a plurality of first electrode fingers 15 and a plurality of third electrode fingers 17 are disposed on the piezoelectric layer 4B. The first main surface 4a of each insulating layer 19 in the piezoelectric layer 4B is configured to cover each first electrode finger 15.

[0122] In this modified example, on the outer side of the intersection region E, no portion of the third busbar 14 adjacent to the first comb electrode 7 in the orthogonal direction of the electrode fingers is directly disposed on the first main surface 4a of the piezoelectric layer 4B. Furthermore, multiple through holes 4c are provided between the multiple first electrode fingers 15 and the multiple third electrode fingers 17. This further suppresses unwanted waves and further suppresses the degradation of filter characteristics.

[0123] The structures of the first and second modifications can also be applied to other structures of the present invention in which a third busbar 14 is provided between the intersection region E and the first busbar 12. Furthermore, when the third busbar 14 does not include the common connecting portion 14a, the end edge of the third busbar 14 is the end edge of the strip portion 14b.

[0124] Figure 9 This is a schematic top view of the elastic wave device according to the second embodiment.

[0125] The difference between this embodiment and the first embodiment is that the third busbar 24 in the functional electrode 21 does not include Figure 2 The common connection portion 14a and the through hole 4c in the piezoelectric layer 4C are shown. The third busbar 24 is provided on the plurality of third electrode fingers 17 and the plurality of insulating layers 19. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device 10 of the first embodiment.

[0126] Multiple through holes 4c are provided in the piezoelectric layer 4C in a portion that, when viewed from above, does not overlap with the plurality of first electrode fingers 15 and the plurality of third electrode fingers 17 but overlaps with the third busbar 24. In addition, multiple through holes 4c are also provided in the portion of the piezoelectric layer 4C located between the third busbar 24 and the first busbar 12 and between the plurality of first electrode fingers 15.

[0127] These through holes 4c reach the support member 3. Therefore, a portion of the third busbar 24 is supported by the support member 3. On the other hand, a plurality of first electrode fingers 15 and a plurality of third electrode fingers 17 are disposed on the piezoelectric layer 4C. The first main surface 4a of each insulating layer 19 in the piezoelectric layer 4C is configured to cover each first electrode finger 15.

[0128] The portion of the third busbar 24, excluding the part overlapping with the first electrode finger 15 in a top view, is adjacent to the first electrode finger 15 in the orthogonal direction of the electrode fingers. Therefore, the aforementioned portion of the third busbar 24 and the first electrode finger 15 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. In this embodiment, the third busbar 24, located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials, is not directly disposed on the first main surface 4a of the piezoelectric layer 4C. Furthermore, a through-hole 4c is provided between the first electrode finger 15 and the third electrode finger 17 in the piezoelectric layer 4C. This effectively suppresses unwanted waves and effectively suppresses the degradation of filter characteristics.

[0129] Furthermore, in this embodiment, in the portion where the third busbar 24 is stacked with the insulating layer 19 and the first electrode finger 15, the first electrode finger 15, the insulating layer 19, and the third busbar 24 are stacked sequentially from the piezoelectric layer 4C side. However, the stacking order of the first electrode finger 15, the insulating layer 19, and the third busbar 24 is not limited to the above.

[0130] For example, in Figure 10 In the modified example of the second embodiment shown, in the portion where the third busbar 24 is stacked with the insulating layer 19 and the first electrode finger 15, the third busbar 24, the insulating layer 19, and the first electrode finger 15 are stacked sequentially from the piezoelectric layer 4C side. More specifically, an insulating layer 19 is disposed between the third busbar 24 and one first electrode finger 15.

[0131] Furthermore, a plurality of insulating layers 19 are provided on the third busbar 24. The plurality of insulating layers 19 are arranged along the orthogonal direction of the electrode fingers. Each insulating layer 19 is located between the third busbar 24 and a first electrode finger 15. Thus, the first comb electrode 7 and the third electrode 29 are electrically insulated. The structure of the electrodes connected to different potentials in this modification, which are separated from each other by the portions of the intersecting insulating layers 19, can also be applied to the structure of the present invention other than this modification.

[0132] In this variant, similar to the second embodiment, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0133] Figure 11 This is a schematic top view of the elastic wave device according to the third embodiment.

[0134] The difference between this embodiment and the second embodiment lies in the structure of the functional electrode 31 and the position of the through hole 4c in the piezoelectric layer 4D. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device of the second embodiment.

[0135] In the functional electrode 31, the third busbar 24 is located in the region between the intersection region E and the second busbar 13. In other words, the third busbar 24 is located in the region between the tips of the plurality of first electrode fingers 15 and the second busbar 13. Therefore, the tips of the plurality of first electrode fingers 15 are spaced apart in the electrode finger extension direction and face the third busbar 24. On the other hand, the tips of the plurality of second electrode fingers 16 are spaced apart in the electrode finger extension direction and face the first busbar 12.

[0136] Multiple through holes 4c are provided in the portion of the piezoelectric layer 4D that does not overlap with the multiple second electrode fingers 16 and the multiple third electrode fingers 17 when viewed from above, but overlaps with the third bus bar 24. In addition, multiple through holes 4c are also provided in the portion of the piezoelectric layer 4D located between the third bus bar 24 and the second bus bar 13 and between the multiple second electrode fingers 16.

[0137] These through holes 4c reach the support member 3. Therefore, a portion of the third busbar 24 is supported by the support member 3. On the other hand, a plurality of second electrode fingers 16 and a plurality of third electrode fingers 17 are disposed on the piezoelectric layer 4D. The first main surface 4a of each insulating layer 19 in the piezoelectric layer 4D is configured to cover each second electrode finger 16.

[0138] The portion of the third busbar 24, excluding the part overlapping with the second electrode finger 16 in top view, is adjacent to the second electrode finger 16 in the orthogonal direction of the electrode fingers. Therefore, the aforementioned portion of the third busbar 24 and the second electrode finger 16 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. In this embodiment, the third busbar 24, located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials, is not directly disposed on the first main surface 4a of the piezoelectric layer 4D. Furthermore, a through-hole 4c is provided between the second electrode finger 16 and the third electrode finger 17 in the piezoelectric layer 4D. This effectively suppresses unwanted waves and effectively suppresses the degradation of filter characteristics.

[0139] In the functional electrode 31, the second electrode finger 16 of the second comb electrode 8 is connected to the output potential. The third bus bar 24 of the third electrode 29 is connected to the reference potential. Therefore, in the portion overlapping with the third bus bar 24 when viewed from above, the electrode connected to the output potential and the electrode connected to the reference potential are adjacent in the orthogonal direction of the electrode fingers. On the other hand, in Figure 9 In the second embodiment shown, at the portion overlapping with the third busbar 24 in a top view, the electrode connected to the input potential and the electrode connected to the reference potential are adjacent in the electrode pointing orthogonal direction.

[0140] In the third embodiment, the second comb electrode 8 may be connected to the input potential, and the first comb electrode 7 may be connected to the output potential. The structure of this third embodiment is equivalent to the structure of the second embodiment where the first comb electrode is connected to the input potential and the second comb electrode 8 is connected to the output potential. Similarly, in the second embodiment, the first comb electrode 7 may be connected to the output potential, and the second comb electrode 8 may be connected to the input potential. The structure of this second embodiment is equivalent to the structure of the third embodiment where the second comb electrode 8 is connected to the output potential and the first comb electrode 7 is connected to the input potential.

[0141] Alternatively, a through-hole 4c may be provided in the portion of the piezoelectric layer 4D located between the cross region E and the second busbar 13, and between the second electrode finger 16 and the third electrode finger 17 in the orthogonal direction of the electrode fingers. More specifically, the through-hole 4c may be provided in the portion located between the cross region E and the third busbar 24, and between the second electrode finger 16 and the third electrode finger 17 in the orthogonal direction of the electrode fingers. This effectively suppresses unwanted waves. This structure can also be applied to structures of the present invention other than the third embodiment in which the third busbar 24 is provided between the cross region E and the second busbar 13.

[0142] Figure 12 This is a schematic top view of the elastic wave device according to the fourth embodiment.

[0143] The difference between this embodiment and the second embodiment is that the third electrode 49 has two third busbars 44A and a third busbar 44B. The third electrode 49 has a grid-like shape. Another difference between this embodiment and the second embodiment is the position of the plurality of insulating layers 19. Furthermore, another difference between this embodiment and the second embodiment is the position of the through-hole 4c in the piezoelectric layer 4E. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device of the second embodiment.

[0144] A portion of the insulating layers 19 are configured to cover a portion of a first electrode finger 15 on the first main surface 4a of the piezoelectric layer 4E. The remaining insulating layers 19 are configured to cover a portion of a second electrode finger 16 on the first main surface 4a of the piezoelectric layer 4E.

[0145] A third busbar 44A is located between the intersection region E and the first busbar 12. The third busbar 44A overlaps with a plurality of first electrode fingers 15 in top view. More specifically, the third busbar 44A intersects with the plurality of first electrode fingers 15 through an insulating layer 19. Thus, the third busbar 44A and the plurality of first electrode fingers 15 are electrically insulated from each other. On the other hand, the third busbar 44A electrically connects a plurality of third electrode fingers 17.

[0146] Another third busbar 44B is located between the intersection region E and the second busbar 13. The third busbar 44B overlaps with a plurality of second electrode fingers 16 in top view. More specifically, the third busbar 44B intersects with the plurality of second electrode fingers 16 through an insulating layer 19. Thus, the third busbar 44B and the plurality of second electrode fingers 16 are electrically insulated from each other. On the other hand, the third busbar 44B electrically connects a plurality of third electrode fingers 17.

[0147] In the piezoelectric layer 4E, a portion of the through holes 4c are arranged in the same manner as in the second embodiment. Specifically, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4E that does not overlap with the plurality of first electrode fingers 15 and the plurality of third electrode fingers 17 when viewed from above, but overlaps with the third busbar 44A. Furthermore, a plurality of through holes 4c are also provided in the portion of the piezoelectric layer 4E located between the third busbar 44A and the first busbar 12, and located between the plurality of first electrode fingers 15.

[0148] Other through holes 4c are provided in the piezoelectric layer 4E in a portion that, when viewed from above, does not overlap with the multiple second electrode fingers 16 and the multiple third electrode fingers 17 but overlaps with the third busbar 44B. In addition, multiple through holes 4c are also provided in the portion of the piezoelectric layer 4E located between the third busbar 44B and the second busbar 13 and between the multiple second electrode fingers 16.

[0149] These through holes 4c reach the support member 3. Therefore, a portion of the third busbar 44A and the third busbar 44B are supported by the support member 3. On the other hand, a plurality of first electrode fingers 15, a plurality of second electrode fingers 16 and a plurality of third electrode fingers 17 are disposed on the piezoelectric layer 4E.

[0150] In a third busbar 44A, the portion other than the part overlapping with the first electrode finger 15 when viewed from above is adjacent to the first electrode finger 15 in the orthogonal direction of the electrode fingers. The aforementioned portion of the third busbar 44A and the first electrode finger 15 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. In another third busbar 44B, the portion other than the part overlapping with the second electrode finger 16 when viewed from above is adjacent to the second electrode finger 16 in the orthogonal direction of the electrode fingers. The aforementioned portion of the third busbar 44B and the second electrode finger 16 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials.

[0151] Furthermore, in this embodiment, the third busbar 44A and the third busbar 44B are not directly disposed on the first main surface 4a of the piezoelectric layer 4E. In addition, through-holes 4c are provided between the first electrode finger 15 and the third electrode finger 17, and between the second electrode finger 16 and the third electrode finger 17, in the piezoelectric layer 4E. This effectively suppresses unwanted waves and effectively suppresses the degradation of filter characteristics.

[0152] Furthermore, at least a portion of the piezoelectric layer 4E located between the cross region E and the first busbar 12, and between the first comb electrode 7 and the third electrode 49 in the orthogonal direction of the electrode fingers, may be provided with a through-hole 4c. In this case, the first electrode finger 15 can be connected to either the input potential or the output potential. Moreover, it is preferable that at least a portion of the piezoelectric layer 4E located between the cross region E and the second busbar 13, and between the second comb electrode 8 and the third electrode 49 in the orthogonal direction of the electrode fingers, is also provided with a through-hole 4c. This allows for more reliable and effective suppression of unwanted waves.

[0153] Figure 13 This is a schematic top view of the elastic wave device according to the fifth embodiment.

[0154] The difference between this embodiment and the fourth embodiment lies in the positional relationship between the second comb-shaped electrode 8 and the third electrode 49. Another difference lies in the position of the through-hole 4c in the piezoelectric layer 4F. Furthermore, the difference lies in the arrangement of the insulating layer 19. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device of the fourth embodiment.

[0155] Viewed from above, the second busbar 13 is located between the crossover region E and the third busbar 44B. In other words, the third busbar 44B is configured to sandwich the second busbar 13 together with the crossover region E. Viewed from above, the second busbar 13 overlaps with a plurality of third electrode fingers 17. The second busbar 13 and the plurality of third electrode fingers 17 are electrically insulated from each other by an insulating layer 19.

[0156] Specifically, the insulating layer 19 is configured to cover the third electrode finger 17 on the first main surface 4a of the piezoelectric layer 4F. More specifically, one insulating layer 19 covers a portion of the extension direction of one third electrode finger 17. Multiple insulating layers 19 are arranged along the orthogonal direction of the electrode fingers. Each insulating layer 19 is configured to cover a portion of one third electrode finger 17. A second busbar 13 is provided on the first main surface 4a, covering the multiple insulating layers 19.

[0157] Thus, the plurality of third electrode fingers 17, which are part of the third electrode 49, and the second busbar 13, which is part of the second comb electrode 8, intersect on the piezoelectric layer 4F separated by an insulating layer 19. Consequently, the second busbar 13 and the plurality of third electrode fingers 17 are electrically insulated from each other. Furthermore, the third busbar 44A and the plurality of first electrode fingers 15, similarly to the fourth embodiment, intersect separated by an insulating layer 19.

[0158] In the piezoelectric layer 4F, a portion of the through holes 4c are arranged in the same manner as the through holes 4c on the side of the first busbar 12 in the second and fourth embodiments. The remaining through holes 4c are located in the piezoelectric layer 4F in a portion that, when viewed from above, does not overlap with the multiple third electrode fingers 17 but overlaps with the second busbar 13. Furthermore, multiple through holes 4c are also provided in the portion of the piezoelectric layer 4F located between the second busbar 13 and the third busbar 44B and between the multiple third electrode fingers 17.

[0159] These through holes 4c reach the support member 3. Therefore, the third busbar 44A and a portion of the second busbar 13 are supported by the support member 3. On the other hand, a plurality of first electrode fingers 15, a plurality of second electrode fingers 16 and a plurality of third electrode fingers 17 are disposed on the piezoelectric layer 4F.

[0160] In this embodiment, the portion of the second busbar 13 other than the portion overlapping with the third electrode finger 17 in top view is adjacent to the third electrode finger 17 in the orthogonal direction of the electrode fingers. The aforementioned portion of the second busbar 13 and the third electrode finger 17 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. On the other hand, similarly to the fourth embodiment, the portion of the third busbar 44A other than the portion overlapping with the first electrode finger 15 in top view is adjacent to the first electrode finger 15 in the orthogonal direction of the electrode fingers. The aforementioned portion of the third busbar 44A and the first electrode finger 15 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials.

[0161] Furthermore, in this embodiment, the third busbar 44A and the second busbar 13 are not directly disposed on the first main surface 4a of the piezoelectric layer 4F. Therefore, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0162] In the functional electrode 41A, the second bus 13 is disposed between the cross region E and the third bus 44B. Alternatively, the first bus 12 may also be disposed between the cross region E and the third bus 44A.

[0163] Figure 14 This is a schematic top view of the elastic wave device according to the sixth embodiment.

[0164] The difference between this embodiment and the fifth embodiment lies in the positional relationship between the first comb-shaped electrode 7 and the third electrode 49. Another difference lies in the position of the through-hole 4c in the piezoelectric layer 4G. Furthermore, the difference lies in the arrangement of the insulating layer 19. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device of the fifth embodiment.

[0165] The first busbar 12 is located between the crossover region E and the third busbar 44A. In other words, the third busbar 44A is configured to sandwich the first busbar 12 together with the crossover region E. The first busbar 12 overlaps with a plurality of third electrode fingers 17 in top view. The first busbar 12 and the plurality of third electrode fingers 17 are electrically insulated from each other by an insulating layer 19.

[0166] Specifically, the insulating layer 19 is configured to cover the third electrode finger 17 on the first main surface 4a of the piezoelectric layer 4G. More specifically, one insulating layer 19 covers a portion of the extension direction of one third electrode finger 17. Multiple insulating layers 19 are arranged along the orthogonal direction of the electrode fingers. Each insulating layer 19 is configured to cover a portion of one third electrode finger 17. A first busbar 12 is provided on the first main surface 4a, covering the multiple insulating layers 19.

[0167] Thus, the plurality of third electrode fingers 17, which are part of the third electrode 49, and the first busbar 12, which is part of the first comb electrode 7, intersect on the piezoelectric layer 4G separated by an insulating layer 19. Therefore, the first busbar 12 and the plurality of third electrode fingers 17 are electrically insulated from each other. Furthermore, the second busbar 13 and the plurality of third electrode fingers 17, similarly to the fifth embodiment, intersect separated by an insulating layer 19.

[0168] In the piezoelectric layer 4G, a portion of all the through holes 4c are provided in the portion of the piezoelectric layer 4G that, when viewed from above, does not overlap with the plurality of third electrode fingers 17 but overlaps with the first busbar 12. Furthermore, a plurality of through holes 4c are also provided in the portion of the piezoelectric layer 4G located between the first busbar 12 and the third busbar 44A and between the plurality of third electrode fingers 17. The remaining plurality of through holes 4c are configured in the same manner as the plurality of through holes 4c on the second busbar 13 side in the fifth embodiment.

[0169] These through holes 4c reach the support member 3. Therefore, a portion of the first busbar 12 and the second busbar 13 are supported by the support member 3. On the other hand, a plurality of first electrode fingers 15, a plurality of second electrode fingers 16 and a plurality of third electrode fingers 17 are disposed on the piezoelectric layer 4G.

[0170] In this embodiment, the portion of the first busbar 12 other than the portion overlapping with the third electrode finger 17 when viewed from above is adjacent to the third electrode finger 17 in the orthogonal direction of the electrode fingers. The aforementioned portion of the first busbar 12 and the third electrode finger 17 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. On the other hand, similarly to the fifth embodiment, the portion of the second busbar 13 other than the portion overlapping with the third electrode finger 17 when viewed from above is adjacent to the third electrode finger 17 in the orthogonal direction of the electrode fingers. The aforementioned portion of the second busbar 13 and the third electrode finger 17 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials.

[0171] Furthermore, in this embodiment, the first busbar 12 and the second busbar 13 are not directly disposed on the first main surface 4a of the piezoelectric layer 4G. As a result, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0172] Furthermore, the configuration of the through-hole 4c in the piezoelectric layer 4G is not limited to the above. Hereinafter, a variation of the sixth embodiment is shown, differing only in the configuration of the through-hole 4c from the sixth embodiment. In this variation of the sixth embodiment, as in the sixth embodiment, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0173] exist Figure 15 In the modified example shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4H located between the cross region E and the first busbar 12 and between the plurality of first electrode fingers 15 and the plurality of third electrode fingers 17. This structure can also be applied to other structures of the present invention where the first busbar 12 is provided between the cross region E and the third busbar 44A.

[0174] A plurality of through holes 4c are provided in the portion of the piezoelectric layer 4H located between the cross region E and the second busbar 13 and between the plurality of second electrode fingers 16 and the plurality of third electrode fingers 17. This structure can also be applied to other structures of the present invention where the second busbar 13 is provided between the cross region E and the third busbar 44B. In this modified example, the remaining plurality of through holes 4c are provided in the same manner as in the sixth embodiment.

[0175] In this modified example, outside the cross region E, no portion of the third busbar 44A adjacent to the first comb electrode 7 in the orthogonal direction of the electrode fingers is directly disposed on the first main surface 4a of the piezoelectric layer 4H. Similarly, outside the cross region E, no portion of the third busbar 44B adjacent to the second comb electrode 8 in the orthogonal direction of the electrode fingers is directly disposed on the first main surface 4a of the piezoelectric layer 4H. Furthermore, multiple through holes 4c are provided between the multiple first electrode fingers 15 and the multiple third electrode fingers 17, and between the multiple second electrode fingers 16 and the multiple third electrode fingers 17. This further suppresses unwanted waves and further suppresses the degradation of filter characteristics.

[0176] Additionally, at least a portion of the piezoelectric layer 4H located between the cross region E and the first busbar 12, and between the first comb electrode 7 and the third electrode 49 in the orthogonal direction of the electrode fingers, may be provided with a through hole 4c. For example, at least one through hole 4c may be provided only in at least a portion of the piezoelectric layer 4H located between the plurality of first electrode fingers 15 and the plurality of third electrode fingers 17.

[0177] Alternatively, a through-hole 4c may be provided in at least a portion of the piezoelectric layer 4H located between the cross region E and the second busbar 13 and between the second comb electrode 8 and the third electrode 49 in the orthogonal direction of the electrode fingers. For example, at least one through-hole 4c may be provided only in at least a portion of the piezoelectric layer 4H located between the plurality of second electrode fingers 16 and the plurality of third electrode fingers 17.

[0178] Figure 16 This is a schematic top view showing a portion of the elastic wave device according to the seventh embodiment. Figure 17 It is along Figure 16 A schematic cross-sectional view of line III-III. Additionally, in Figure 16 In the diagram, the insulating layer 19 is indicated by a shaded line.

[0179] like Figure 16 As shown, the difference between this embodiment and the first embodiment lies in the structure of the functional electrode 51. For example... Figure 17 As shown, this embodiment differs from the first embodiment in that the support member 53 only includes a support base plate. (Return) Figure 16 The difference between this embodiment and the first embodiment lies in the position of the through hole 4c in the piezoelectric layer 4I. Apart from the above, the elastic wave device of this embodiment has the same structure as the elastic wave device 10 of the first embodiment.

[0180] In the first comb-shaped electrode 57 of the functional electrode 51, the width of the first electrode finger 55 is not fixed. Specifically, the portion of the first electrode finger 55 located outside the intersection region E has a wider portion and a narrower portion. More specifically, the wider portion of the first electrode finger 55 is located on the side of the first busbar 12. On the other hand, the narrower portion of the first electrode finger 55 is located on the side of the intersection region E. The width of the narrower portion of the first electrode finger 55 is the same as the width of the portion of the first electrode finger 55 located in the intersection region E. Furthermore, the width of the electrode finger refers to the dimension of the electrode finger along the orthogonal direction of the electrode finger.

[0181] Similarly, the portion of the second electrode finger 56 of the second comb electrode 58 located outside the intersection region E also has a wider portion and a narrower portion. The wider portion of the second electrode finger 56 is located on the side of the second busbar 13. The narrower portion of the second electrode finger 56 is located on the side of the intersection region E. The width of the narrower portion of the second electrode finger 56 is the same as the width of the portion of the second electrode finger 56 located in the intersection region E.

[0182] The third electrode 59 has two third busbars 54A and 54B. Each third busbar has multiple common connection portions 54a and bar portions 54b. The multiple common connection portions 54a in one third busbar 54A extend toward the intersection region E. The multiple common connection portions 54a in the other third busbar 54B also extend toward the intersection region E. However, none of the common connection portions 54a reach the intersection region E. The common connection portions 54a of the third busbar 54A and the common connection portions 54a of the third busbar 54B respectively connect an adjacent pair of third electrode fingers 17 to each other.

[0183] A plurality of common connection portions 54a of a third busbar 54A, a plurality of common connection portions 54a of another third busbar 54B, and a plurality of third electrode fingers 17 are connected in a meandering manner. Specifically, a common connection portion 54a of another third busbar 54B connects to two adjacent third electrode fingers 17 in a third busbar 54A that are connected to two adjacent common connection portions 54a. Similarly, a common connection portion 54a of a third busbar 54A connects to two adjacent third electrode fingers 17 in a third busbar 54B that are connected to two adjacent common connection portions 54a.

[0184] Multiple common connection portions 54a in a third busbar 54A are connected by a strip portion 54b. The width of each common connection portion 54a is not fixed. Specifically, the common connection portion 54a has a wider portion and a narrower portion. The narrower portion of the common connection portion 54a is located on the strip portion 54b side, which is wider than the wider portion. Therefore, a pair of third electrode fingers 17 are connected to the wider portion of the common connection portion 54a. In addition, the width of the common connection portion 54a in this embodiment is the dimension of the common connection portion 54a along the orthogonal direction of the electrode fingers.

[0185] The strip portion 54b of the third busbar 54A and the plurality of first electrode fingers 55 overlap in top view. In this embodiment, a strip-shaped insulating layer 19 is configured to cover a portion of each of the plurality of first electrode fingers 55 on the first main surface 4a of the piezoelectric layer 4I. The strip portion 54b is provided on the insulating layer 19. Thus, the first comb-shaped electrode 57 and the third electrode 59 are electrically insulated from each other. In addition, the wider portion of each first electrode finger 55 extends to a position closer to the intersection region E than the insulating layer 19.

[0186] Multiple common connecting portions 54a in another third busbar 54B are connected via a strip portion 54b. The width of each common connecting portion 54a is not fixed. Each common connecting portion 54a has a wider portion and a narrower portion. The narrower portion of the common connecting portion 54a is located on the strip portion 54b side, which is wider than the wider portion. Therefore, a pair of third electrode fingers 17 are connected to the wider portion of the common connecting portion 54a.

[0187] The strip portion 54b of the third busbar 54B and the plurality of second electrode fingers 56 overlap in top view. In this embodiment, a strip-shaped insulating layer 19 is configured to cover a portion of each of the plurality of second electrode fingers 56 on the first main surface 4a of the piezoelectric layer 4I. The strip portion 54b is provided on the insulating layer 19. Thus, the second comb-shaped electrode 58 and the third electrode 59 are electrically insulated from each other. In addition, the wider portion of each second electrode finger 56 extends to a position closer to the intersection region E than the insulating layer 19.

[0188] like Figure 17 As shown, in this embodiment, a through hole as a cavity 50a is provided in the support substrate serving as the support member 53. This cavity 50a is the sound reflection portion in this embodiment. The first busbar 12 and the second busbar 13 are supported by the support member 53. Furthermore, the support member 53 supports the strip portion 54b of the third busbar 54A and a portion of the plurality of common connecting portions 54a. Similarly, Figure 16 The strip portion 54b of the third busbar 54B shown and a portion of the plurality of common connecting portions 54a are supported by the support member 53.

[0189] Multiple through holes 4c are provided in the piezoelectric layer 4I. A portion of all the through holes 4c are provided in the piezoelectric layer 4I between multiple common connection portions 54a of a third busbar 54A and multiple first electrode fingers 55.

[0190] More specifically, in the piezoelectric layer 4I, between a common connection portion 54a of the third busbar 54A and a first electrode finger 55, two through holes 4c are provided in the extension direction of the electrode finger. One through hole 4c is adjacent to the wider and narrower portions of the first electrode finger 55 in the orthogonal direction of the electrode finger. The through hole 4c is adjacent to the narrower and wider portions of the common connection portion 54a in the orthogonal direction of the electrode finger.

[0191] Another through hole 4c is adjacent only to the narrower portion of the first electrode finger 55 in the orthogonal direction of the electrode fingers. This through hole 4c is adjacent only to the wider portion of the common connection 54a in the orthogonal direction of the electrode fingers.

[0192] Other through holes 4c are disposed in the piezoelectric layer 4I between a plurality of common connection portions 54a and a plurality of second electrode fingers 56 of another third busbar 54B. More specifically, in the piezoelectric layer 4I, in the portion between a common connection portion 54a of the third busbar 54B and a second electrode finger 56, two through holes 4c are provided in the electrode finger extension direction. One through hole 4c is adjacent to the wider and narrower portions of the second electrode finger 56 in the orthogonal direction of the electrode finger. This through hole 4c is adjacent to the narrower and wider portions of the common connection portion 54a in the orthogonal direction of the electrode finger.

[0193] Another through hole 4c is adjacent only to the narrower portion of the second electrode finger 56 in the orthogonal direction of the electrode fingers. This through hole 4c is also adjacent only to the wider portion of the common connecting part 54a in the orthogonal direction of the electrode fingers.

[0194] In addition, in this embodiment, the through hole 4c is not provided in the portion that overlaps with the third busbar 54A and the third busbar 54B when viewed from above.

[0195] In this embodiment, a through-hole 4c is also provided in the piezoelectric layer 4I, located outside the cross region E and between electrodes that are adjacent to each other in the orthogonal direction of the electrodes and connected to each other with different potentials. This allows for the suppression of unwanted waves and the mitigation of filter characteristics.

[0196] In the elastic wave device with the structure of this embodiment, S-parameters were derived through FEM simulation. The design parameters of the above elastic wave device are as follows. Furthermore, the distance between the tip of the electrode finger and the busbar is defined as the BE gap. The width of the electrode finger is defined as Mark.

[0197] Piezoelectric layer: Material…LiNbO3, cleavage angle…120°Y, thickness…360nm

[0198] The first electrode refers to the third electrode: layer structure... Ti layer / Al layer starting from the piezoelectric layer side, thickness... 12nm / 360nm starting from the piezoelectric layer side.

[0199] The center-to-center distance between the first and third electrode fingers: 1.26 μm

[0200] The center-to-center distance between the second and third electrode fingers: 1.26 μm

[0201] BE gap: 2μm

[0202] Mark: 360nm

[0203] Insulator layer: Material…SiO2, thickness…0.0675μm

[0204] Figure 18 This is a diagram illustrating the passage characteristics in the seventh embodiment.

[0205] like Figure 18 As shown, in this embodiment, ripple is suppressed within the passband. Thus, in this embodiment, unwanted waves can be suppressed, and the degradation of filter characteristics can be suppressed.

[0206] Figure 19 This is a schematic top view of the elastic wave device according to the eighth embodiment.

[0207] The difference between this embodiment and the second embodiment lies in the positional relationship between the first comb-shaped electrode 7 and the third electrode 29. Another difference lies in the position of the plurality of insulating layers 19. Furthermore, the difference lies in the position of the through-hole 4c in the piezoelectric layer 4J. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device of the second embodiment.

[0208] The structure in this embodiment that is closer to the third busbar 24 than the intersection region E is the same as... Figure 14 The structure in the sixth embodiment shown is the same as that on the side of the third busbar 44A closer to the intersection region E. Specifically, as... Figure 19 As shown, the first busbar 12 is located between the intersection region E and the third busbar 24. The first busbar 12 overlaps with multiple third electrode fingers 17 in top view. The first busbar 12 and the multiple third electrode fingers 17 are electrically insulated from each other by an insulating layer 19.

[0209] In the piezoelectric layer 4J, multiple through holes 4c and Figure 14 In the sixth embodiment shown, the multiple through holes 4c on the side of the third busbar 44A closer to the intersection region E are similarly provided. Specifically, as Figure 19 As shown, the portion of the piezoelectric layer 4J that, when viewed from above, does not overlap with the plurality of third electrode fingers 17 but overlaps with the first busbar 12. Furthermore, the portion of the piezoelectric layer 4J located between the first busbar 12 and the third busbar 24 and between the plurality of third electrode fingers 17 is also provided with a plurality of through holes 4c.

[0210] In this embodiment, the portion of the first busbar 12 other than the portion overlapping with the third electrode finger 17 in a top view is adjacent to the third electrode finger 17 in the orthogonal direction of the electrode fingers. Therefore, the aforementioned portion of the first busbar 12 and the third electrode finger 17 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. Furthermore, the first busbar 12 is not directly disposed on the first main surface 4a of the piezoelectric layer 4J. As a result, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0211] Figure 20 This is a schematic top view of the elastic wave device according to the ninth embodiment. Additionally, in Figure 20 In the image, the third electrode 29 is not marked with a shaded line.

[0212] The difference between this embodiment and the second embodiment is that a portion of the third electrode 29 is disposed on the second main surface 4b of the piezoelectric layer 4C. Furthermore, the portion of the third electrode 29 not disposed on the second main surface 4b is disposed with... Figure 1 The first embodiment shown is supported by the same support member 3. The difference between this embodiment and the second embodiment is that the insulating layer 19 is not provided. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device of the second embodiment.

[0213] In this embodiment, the top-view configuration of the third electrode 29 is the same as in the second embodiment. Furthermore, the plurality of third electrode fingers 17 are respectively configured on the second main surface 4b of the piezoelectric layer 4C, so that, in the direction in which the first electrode fingers 15 and the second electrode fingers 16 are arranged, they are side-by-side with the first electrode fingers 15 and the second electrode fingers 16 when viewed from above. In the top-view, the order of the plurality of electrode fingers is the same, starting with the first electrode finger 15, then the third electrode finger 17, the second electrode finger 16, and the third electrode finger 17 as a cycle. In the top-view, the third busbar 24 is disposed between the intersection region E and the first busbar 12.

[0214] The arrangement of the plurality of through holes 4c in the piezoelectric layer 4C is the same as in the second embodiment. Therefore, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4C that does not overlap with the plurality of first electrode fingers 15 and the plurality of third electrode fingers 17 when viewed from above, but overlaps with the third busbar 24. In addition, a plurality of through holes 4c are also provided in the portion of the piezoelectric layer 4C located between the third busbar 24 and the first busbar 12 and between the plurality of first electrode fingers 15.

[0215] Furthermore, the third busbar 24 and multiple first electrode fingers 15 are positioned opposite each other, sandwiching a piezoelectric layer 4C. Therefore, the first comb electrode 7 and the third electrode 29 are electrically insulated from each other.

[0216] In this embodiment, a through-hole 4c is provided in the piezoelectric layer 4C, located outside the cross region E and between electrodes that are adjacent to each other in the orthogonal direction of the electrodes and connected to each other with different potentials. This effectively suppresses unwanted waves and effectively prevents the degradation of filter characteristics.

[0217] The structure in the ninth embodiment, in which a portion of the third electrode is disposed on the second main surface of the piezoelectric layer, can also be applied to other structures of the present invention other than the ninth embodiment. For example, a portion of the third electrode in the first embodiment, the third to eighth embodiments, and various modifications can also be disposed on the second main surface. In this case, at least a portion of the portion of the piezoelectric layer located outside the intersection region and located between the first comb electrode or the second comb electrode and the third electrode in the orthogonal direction of the electrodes can be provided with a through hole.

[0218] In the first to ninth embodiments, the through-holes in the piezoelectric layer are voids. However, a dielectric layer or a resin layer may also be provided within the through-holes. This example is shown in the tenth embodiment.

[0219] Figure 21 This is a schematic top view of the elastic wave device according to the tenth embodiment. Figure 22 It is along Figure 21 A schematic cross-sectional view of line IV-IV in the diagram. Figure 21 The dielectric layer, which will be described later, is indicated by a shading.

[0220] like Figure 21 As shown, the difference between this embodiment and the first embodiment lies in the position of the through-hole 4c in the piezoelectric layer 4K and the provision of a dielectric layer 62 within the through-hole 4c. Apart from the above points, the elastic wave device of this embodiment has the same structure as the elastic wave device 10 of the first embodiment.

[0221] A through-hole 4c is configured in the piezoelectric layer 4K to overlap with the third busbar 14 when viewed from above. More specifically, the end edge of the through-hole 4c on the intersection region E side when viewed from above includes an imaginary line connecting the end edges of the intersection regions E side of the plurality of common connecting parts 14a. The end edge of the through-hole 4c on the first busbar 12 side includes the end edge of the first busbar 12 on the intersection region E side. A dielectric layer 62 is filled within the through-hole 4c.

[0222] like Figure 22 As shown, in this embodiment, a portion of a plurality of first electrode fingers 15, a third busbar 14, and a plurality of insulating layers 19 are provided on the dielectric layer 62.

[0223] In this embodiment, the portion of the third busbar 14 other than the portion overlapping with the first electrode finger 15 when viewed from above is adjacent to the first electrode finger 15 in the orthogonal direction of the electrode fingers. Therefore, the aforementioned portion of the third busbar 14 and the first electrode finger 15 are electrodes located outside the intersection region E, adjacent in the orthogonal direction of the electrode fingers, and connected to each other with different potentials. In this embodiment, the portions of these electrodes that are adjacent to each other in the orthogonal direction of the electrode fingers are not directly disposed on the first main surface 4a of the piezoelectric layer 4K. As a result, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0224] The structure in this embodiment, in which a dielectric layer 62 is provided within the through hole 4c, can also be used in structures of the present invention other than those in this embodiment. Alternatively, a resin layer may be provided instead of the dielectric layer 62.

[0225] In the first to tenth embodiments, the third busbar and the plurality of third electrode fingers are disposed on the same main surface in the piezoelectric layer. However, the third busbar and the plurality of third electrode fingers may not necessarily be disposed on the same main surface. An example of the third busbar and the plurality of third electrode fingers being disposed on different main surfaces is shown in the eleventh embodiment.

[0226] Figure 23 This is a schematic top view of the elastic wave device according to the eleventh embodiment. Figure 24 It is along Figure 23 A schematic cross-sectional view of line II in the diagram. Figure 25 It is along Figure 23 A schematic cross-sectional view of the VV line.

[0227] like Figure 23 As shown, the difference between this embodiment and the second embodiment lies in the structure of the third electrode 79. (As illustrated...) Figure 24 As shown, the difference between this embodiment and the second embodiment lies in the structure of the insulating layer 75. Apart from the points mentioned above, the elastic wave device of this embodiment has the same structure as the elastic wave device of the second embodiment.

[0228] like Figure 25 As shown, the third electrode 79 has a third busbar 24, a plurality of third electrode fingers 17, and a plurality of connecting electrodes 78. The plurality of third electrode fingers 17 are disposed on the first main surface 4a of the piezoelectric layer 4L in the same manner as in the second embodiment. Specifically, the plurality of third electrode fingers 17 are directly disposed on the first main surface 4a.

[0229] On the other hand, the third busbar 24 is disposed on the second main surface 4b of the piezoelectric layer 4L. Specifically, the third busbar 24 is directly disposed on the second main surface 4b. The third busbar 24 extends along the orthogonal direction of the electrode fingers. The third busbar 24 is configured to face the piezoelectric layer 4L sandwiched between the plurality of third electrode fingers 17. However, the direction in which the third busbar 24 extends is not limited to the above.

[0230] Multiple connecting electrodes 78 penetrate the piezoelectric layer 4L. Furthermore, one connecting electrode 78 connects a third electrode finger 17 and a third busbar 24. That is, multiple third electrode fingers 17 are electrically connected to the third busbar 24 via multiple connecting electrodes 78.

[0231] like Figure 24 As shown, a hollow portion is provided in the insulating layer 75. That is, a hollow portion, serving as a void 70a, is formed in the insulating layer 75. In this embodiment, the insulating layer 75 covers the second main surface 4b of the piezoelectric layer 4L. Figure 25 As shown, the insulating layer 75 covers the third busbar 24 in the third electrode 79. However, the insulating layer 75 may not necessarily cover the second main surface 4b and the third busbar 24. For example, the insulating layer 75 may also be combined with... Figure 1 The insulating layer 5 shown is similarly provided.

[0232] The difference between the third electrode 79 in this embodiment and that in the second embodiment is that it has multiple connecting electrodes 78. However, Figure 23 The top view configuration of the third electrode 79 is the same as in the second embodiment. Therefore, the plurality of third electrode fingers 17 are respectively configured on the first main surface 4a of the piezoelectric layer 4L, so that, in the top view, they are arranged side-by-side with the first electrode fingers 15 and the second electrode fingers 16 in the direction in which the first electrode fingers 15 and the second electrode fingers 16 are arranged. In the top view, the order of the plurality of electrode fingers is such that, starting with the first electrode finger 15, the first electrode finger 15, the third electrode finger 17, the second electrode finger 16, and the third electrode finger 17 form a cycle.

[0233] When viewed from above, the third busbar 24 is positioned between the intersection region E and the first busbar 12. The third busbar 24 overlaps with multiple first electrode fingers 15 when viewed from above.

[0234] In the piezoelectric layer 4L, multiple through holes 4c are disposed in the portion of the piezoelectric layer 4L that overlaps with the third busbar 24 when viewed from above and is located between multiple first electrode fingers 15 and multiple third electrode fingers 17. Furthermore, the multiple first electrode fingers 15 and the third busbar 24 are disposed on different main surfaces in the piezoelectric layer 4L. Therefore, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0235] Furthermore, the configuration with multiple through holes 4c is not limited to the above. For example, in Figure 26 In the first variation of the eleventh embodiment shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4M that overlaps with the third busbar 24 and the plurality of first electrode fingers 15 when viewed from above. Furthermore, the first electrode fingers 15 are supported by portions of the piezoelectric layer 4M other than those with the through holes 4c. In this case, similar to the eleventh embodiment, unwanted waves can be suppressed, and the degradation of filter characteristics can be suppressed.

[0236] exist Figure 27 In the second modified example shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4N that overlaps with the third busbar 24 in plan view and is located between the plurality of third electrode fingers 17. Therefore, the plurality of through holes 4c are also located in the portion that overlaps with the first electrode fingers 15 in plan view. In this modified example, a dielectric layer 62 is provided within the plurality of through holes 4c. A portion of the first electrode fingers 15 is provided on the dielectric layer 62. Alternatively, a resin layer may be provided instead of the dielectric layer 62.

[0237] In this modified example, similar to the eleventh embodiment and the tenth embodiment described above, unwanted waves can be suppressed and the degradation of filter characteristics can be suppressed.

[0238] In the first to eleventh embodiments, the third busbar is disposed on the first or second main surface of the piezoelectric layer. Alternatively, in this invention, the third busbar may also be disposed outside the first and second main surfaces of the piezoelectric layer. Examples are shown in the twelfth and thirteenth embodiments.

[0239] Figure 28 This is a simplified front sectional view of the elastic wave device according to the twelfth embodiment. Figure 28 The diagram illustrates the portion containing the comb-shaped electrodes and multiple third electrodes by adding two diagonal lines to a rectangle. Figure 28 The same applies to the simplified front sectional view, in addition to the above. Figure 28 The cross-section of the portion of the third electrode without the third busbar and connecting electrodes is shown.

[0240] The elastic wave device 80 in this embodiment has a WLP (Wafer Level Package) structure. Specifically, a first support 82, which serves as the support in this invention, is provided on the piezoelectric substrate 2L. More specifically, the first support 82 is provided on the first main surface 4a of the piezoelectric layer 4L. The first support 82 has a frame-like shape. Therefore, the first support 82 has an opening 82a.

[0241] On the first main surface 4a of the piezoelectric layer 4L, a first comb-shaped electrode, a second comb-shaped electrode, and a plurality of third electrode fingers of the functional electrode 81 are provided. When the portion of the piezoelectric layer 4L in which each comb-shaped electrode and a plurality of third electrode fingers are provided is designated as the element electrode forming portion F, the element electrode forming portion F is located within the opening portion 82a.

[0242] A plurality of second supports 83 are provided on the first main surface 4a of the piezoelectric layer 4L. The second supports 83 have a columnar shape. The plurality of second supports 83 are located within the opening 82a of the first support 82. In this embodiment, the first support 82 and the second supports 83 are respectively laminates of multiple metal layers. Alternatively, the second supports 83 may not be provided.

[0243] A cover member 84 is provided on the first support 82 and the plurality of second supports 83 to block the opening 82a. This forms a hollow portion surrounded by the piezoelectric substrate 2L, the first support 82, and the cover member 84. The element electrode forming portion F in the piezoelectric layer 4L is located within this hollow portion.

[0244] The cover member 84 has a cover member body 84A and an inorganic oxide layer 84B. The cover member body 84A has a pair of main surfaces. The two main surfaces are opposite to each other. One main surface of the cover member body 84A is opposite to the piezoelectric substrate 2L. The inorganic oxide layer 84B is disposed on the two main surfaces of the cover member body 84A.

[0245] More specifically, the cover member 84 has a third main surface 84a and a fourth main surface 84b. The third main surface 84a and the fourth main surface 84b are opposite to each other. The third main surface 84a is the main surface on the piezoelectric substrate 2L side. In addition, the main surface of the cover member 84 is the surface of the inorganic oxide layer 84B. More specifically, the main surface of the cover member 84 is the surface of the portion of the inorganic oxide layer 84B disposed on the main surface of the cover member body 84A. However, the inorganic oxide layer 84B may not be provided. In this case, the third main surface 84a and the fourth main surface 84b of the cover member 84 are the main surfaces of the cover member body 84A.

[0246] In this embodiment, the cover member body 84A is a silicon substrate. Additionally, the support substrate 6 in the piezoelectric substrate 2L is also a silicon substrate. However, the materials of the support substrate 6 and the cover member body 84A are not limited to those described above.

[0247] A through electrode 85 is provided in the cover member 84. More specifically, a through hole is provided in the cover member 84. This through hole is configured to reach the second support body 83. The through electrode 85 is provided within the through hole. One end of the through electrode 85 is connected to the second support body 83. An external terminal 86 is provided to connect to the other end of the through electrode 85. The external terminal 86 is configured as an electrode pad. In this embodiment, the through electrode 85 and the external terminal 86 are integrated. However, the through electrode 85 and the external terminal 86 may also be provided separately.

[0248] The inorganic oxide layer 84B of the cover member 84 is disposed not only on the main surface of the cover member body 84A, but also within the through hole. More specifically, within the through hole, the inorganic oxide layer 84B is located between the through electrode 85 and the cover member body 84A. The inorganic oxide layer 84B is configured to cover the vicinity of the outer periphery of the external terminal 86. The inorganic oxide layer 84B extends between the external terminal 86 and the cover member body 84A. The inorganic oxide layer 84B is, for example, a silicon oxide layer. However, the material of the inorganic oxide layer 84B is not limited to the above.

[0249] Alternatively, the inorganic oxide layer 84B may not be disposed within the through hole of the cover member body 84A. The inorganic oxide layer 84B may also not be disposed on the external terminal 86 or between the external terminal 86 and the cover member body 84A.

[0250] A bump 87, serving as a conductive bonding member, is provided on the portion of the plurality of external terminals 86 not covered by the inorganic oxide layer 84B. The bump 87 may be, for example, a solder bump or an Au bump. Alternatively, the conductive bonding member may be, for example, a conductive adhesive. The conductive bonding member is electrically connected to an external reference potential or signal potential.

[0251] Figure 29 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the twelfth embodiment.

[0252] The third busbar 24 of the third electrode 89 is disposed on the third main surface 84a of the cover member 84. The third busbar 24 is opposite to a portion of the plurality of third electrode fingers 17.

[0253] Multiple connecting electrodes 88 in the third electrode 89 are disposed between the first main surface 4a of the piezoelectric layer 4L and the cover member 84. The connecting electrodes 88 are columnar electrodes. More specifically, each connecting electrode 88 is disposed on a third electrode finger 17 and on the piezoelectric layer 4L. Furthermore, each connecting electrode 88 is connected to the third busbar 24. That is, the multiple connecting electrodes 88 connect the third busbar 24 to the multiple third electrode fingers 17.

[0254] However, each connecting electrode 88 may be disposed on at least the third electrode finger 17. Alternatively, at least one connecting electrode 88 may be disposed only on the third electrode finger 17. In this case, the connecting electrode 88 is not directly disposed on the piezoelectric layer 4L.

[0255] Figure 30 This is a schematic top view showing the electrode structure on the first main surface of the piezoelectric layer in the twelfth embodiment. Additionally, the above-mentioned... Figure 29 It shows along Figure 30 A schematic cross-sectional view of the VV line portion.

[0256] like Figure 30 As shown, the third busbar 24 is disposed in the portion overlapping the outer region of the electrode fingers in the extension direction of the intersection region E when viewed from above. Specifically, when viewed from above, the third busbar 24 is disposed between the intersection region E and the first busbar 12. The third busbar 24 overlaps with a plurality of first electrode fingers 15 when viewed from above. The third busbar 24 is connected via other wiring, Figure 28 The through electrode 85 and bump 87 shown are electrically connected to the reference potential.

[0257] return Figure 29 In this embodiment, the piezoelectric layer 4L is provided with multiple through holes 4c in the same manner as in the eleventh embodiment. Specifically, in the piezoelectric layer 4L, the multiple through holes 4c are provided in the portion of the piezoelectric layer 4L that overlaps with the third busbar 24 in top view and is located between the multiple first electrode fingers 15 and the multiple third electrode fingers 17. Furthermore, the third busbar 24 is provided on the cover member 84. As a result, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0258] Furthermore, the configuration with multiple through holes 4c is not limited to the above. For example, in Figure 31 In the first variation of the twelfth embodiment shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4M that overlaps with the third busbar 24 and the plurality of first electrode fingers 15 when viewed from above. Furthermore, the first electrode fingers 15 are supported by portions of the piezoelectric layer 4M other than those with the through holes 4c. In this variation, similar to the twelfth embodiment, unwanted waves can be suppressed, and the degradation of filter characteristics can be suppressed.

[0259] exist Figure 32In the second variation of the twelfth embodiment shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4O that overlaps with the third busbar 24 and the plurality of third electrode fingers 17 when viewed from above. Furthermore, the through holes 4c also overlap with the connecting electrode 88 when viewed from above. However, the third electrode fingers 17 and the connecting electrode 88 are supported by portions of the piezoelectric layer 40 other than those provided with the through holes 4c. In this variation, similar to the twelfth embodiment, unwanted waves can be suppressed, and the degradation of filter characteristics can be suppressed.

[0260] return Figure 28 In the twelfth embodiment, the layout on the third main surface 84a of the cover member 84 offers a high degree of freedom. Therefore, it is possible to easily provide a device for [unclear - possibly related to a specific device or mechanism] on the third main surface 84a without requiring an increase in the size of the elastic wave device 80. Figure 29 The wiring shown connects the third electrode 89 to the reference potential. Furthermore, the width of the third busbar 24 can be easily widened. This allows for easy and effective reduction of the resistance of the third electrode 89.

[0261] in addition, Figure 28 The first support 82 shown above can also be disposed on a layer other than the piezoelectric layer 4L in the piezoelectric substrate 2L. More specifically, the support member 3 is, similarly to the first embodiment, a laminate of the support substrate 6 and the insulating layer 5. For example, in plan view, the outer periphery of the piezoelectric layer 4L may be located further inward than the outer periphery of the insulating layer 5 or the support substrate 6. In this case, the first support 82 may also be disposed on the insulating layer 5 or the support substrate 6.

[0262] In the twelfth embodiment, Figure 30 The first comb electrode 7 is connected to the input potential. The second comb electrode 8 is connected to the output potential. Alternatively, the second comb electrode 8 can be connected to the input potential, and the first comb electrode 7 can be connected to the output potential.

[0263] Figure 33 This is a simplified front sectional view of the elastic wave device according to the thirteenth embodiment.

[0264] The elastic wave device 90 has a structure in which an elastic wave resonator is mounted on a mounting substrate 95. Specifically, the elastic wave device 90 is a CSP (Chip Size Package) structure. The mounting substrate 95 is a printed circuit board (PCB). In this embodiment, the material of the mounting substrate 95 is high-temperature co-fired ceramic (HTCC). However, the material of the mounting substrate 95 is not limited to the above.

[0265] On the other hand, the support substrate 6 in the piezoelectric substrate 2L is a silicon substrate. However, the material of the support substrate 6 is not limited to the above.

[0266] A plurality of conductive bonding members are provided on the piezoelectric substrate 2L. More specifically, a plurality of electrode pads 98 are provided on the piezoelectric substrate 2L. Conductive bonding members are provided on each of the plurality of electrode pads 98. In this embodiment, the conductive bonding member is a bump 97. The bump 97 may be, for example, a solder bump or an Au bump.

[0267] The piezoelectric substrate 2L is bonded to the mounting substrate 95 via multiple conductive bonding members. The mounting substrate 95 has a fifth main surface 95a and a sixth main surface 95b. The fifth main surface 95a and the sixth main surface 95b are opposite to each other. The fifth main surface 95a is the main surface on the piezoelectric substrate 2L side. A sealing resin 94 is provided on the fifth main surface 95a to cover the support substrate 6 in the piezoelectric substrate 2L. The piezoelectric substrate 2L, the sealing resin 94, and the mounting substrate 95 constitute a hollow portion. The element electrode forming portion F in the piezoelectric layer 4L is located within this hollow portion.

[0268] A plurality of external terminals 96 are provided on the sixth main surface 95b of the mounting substrate 95. A plurality of via electrodes and a plurality of wirings are provided within the mounting substrate 95. Each external terminal 96 is electrically connected to the via electrodes and wirings within the mounting substrate 95. Furthermore, the plurality of external terminals 96 are electrically connected to an external reference potential or signal potential via bumps or conductive adhesives, etc.

[0269] Figure 34 This is a schematic front cross-sectional view showing an enlarged portion of the elastic wave device according to the thirteenth embodiment.

[0270] In this embodiment, the third busbar 24 of the third electrode 89 is disposed on the fifth main surface 95a of the mounting substrate 95. The third busbar 24 is opposite to a portion of the plurality of third electrode fingers 17.

[0271] Multiple connecting electrodes 88 in the third electrode 89 are disposed between the first main surface 4a of the piezoelectric layer 4L and the fifth main surface 95a of the mounting substrate 95. The connecting electrodes 88 are columnar electrodes. More specifically, each connecting electrode 88 is disposed on only one third electrode finger 17. Furthermore, each connecting electrode 88 is connected to the third busbar 24. That is, multiple connecting electrodes 88 connect the third busbar 24 to multiple third electrode fingers 17. Additionally, each connecting electrode 88 may be disposed on at least one third electrode finger 17. Alternatively, at least one connecting electrode 88 may be disposed throughout both the third electrode finger 17 and the piezoelectric layer 4L.

[0272] Figure 35 This is a schematic top view showing the electrode structure on the first main surface of the piezoelectric layer in the thirteenth embodiment. Furthermore, the above-mentioned... Figure 34 It shows along Figure 35A schematic cross-sectional view of the VV line portion.

[0273] like Figure 35 As shown, the third busbar 24 is located in the portion overlapping the outer region of the electrode fingers in the extension direction of the intersection region E when viewed from above. Specifically, when viewed from above, the third busbar 24 is located between the intersection region E and the first busbar 12. The third busbar 24 overlaps with a plurality of first electrode fingers 15 when viewed from above. The third busbar 24 is via... Figure 33 The wiring on the fifth main surface 95a of the mounting substrate 95, the wiring and via electrodes within the mounting substrate 95, and the external terminal 96 are electrically connected to the reference potential.

[0274] Return to Figure 34 In this embodiment, the piezoelectric layer 4L is provided with a plurality of through holes 4c in the same manner as in the eleventh embodiment. Specifically, the plurality of through holes 4c are provided in the portion of the piezoelectric layer 4L that overlaps with the third busbar 24 in top view and is located between the plurality of first electrode fingers 15 and the plurality of third electrode fingers 17. Furthermore, the third busbar 24 is provided on the mounting substrate 95. As a result, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed.

[0275] Furthermore, the configuration with multiple through holes 4c is not limited to the above. For example, in Figure 36 In the first variation of the thirteenth embodiment shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4M that overlaps with the third busbar 24 and the plurality of first electrode fingers 15 when viewed from above. Furthermore, the first electrode fingers 15 are supported by portions of the piezoelectric layer 4M other than those with the through holes 4c. In this variation, similar to the thirteenth embodiment, unwanted waves can be suppressed, and the degradation of filter characteristics can be suppressed.

[0276] exist Figure 37 In the second variation of the thirteenth embodiment shown, a plurality of through holes 4c are provided in the portion of the piezoelectric layer 4O that overlaps with the third busbar 24 and the plurality of third electrode fingers 17 when viewed from above. Furthermore, the through holes 4c also overlap with the connecting electrode 88 when viewed from above. However, the third electrode fingers 17 and the connecting electrode 88 are supported by portions of the piezoelectric layer 40 other than those provided with the through holes 4c. In this variation, similar to the thirteenth embodiment, unwanted waves can be suppressed, and the degradation of filter characteristics can be suppressed.

[0277] return Figure 33 In this embodiment, the layout on the fifth main surface 95a of the mounting substrate 95 offers a high degree of freedom. Therefore, it is possible to easily provide a device for [unclear - possibly related to a specific device or mechanism] on the fifth main surface 95a without requiring the elastic wave device 90 to be enlarged. Figure 34The wiring shown connects the third electrode 89 to the reference potential. Furthermore, the width of the third busbar 24 can be easily widened. This allows for easy and effective reduction of the resistance of the third electrode 89.

[0278] In this embodiment, Figure 35 The first comb electrode 7 is connected to the input potential. The second comb electrode 8 is connected to the output potential. Alternatively, the second comb electrode 8 can be connected to the input potential, and the first comb electrode 7 can be connected to the output potential.

[0279] In the twelfth and thirteenth embodiments, the arrangement of the third busbar 24 and the arrangement of the through holes in the piezoelectric layer 4L when viewed from above are the same as in the eleventh embodiment. However, the through holes 4c can be provided in at least a portion of the portion of the piezoelectric layer 4L located outside the intersection region E and located between the first comb electrode 7 or the second comb electrode 8 and the third electrode 89 in the orthogonal direction of the electrodes.

[0280] In the first to thirteenth embodiments, the acoustic reflective portion is a void in the piezoelectric substrate. Alternatively, the acoustic reflective portion may also be an acoustic reflective film. This example is shown in the fourteenth embodiment.

[0281] Figure 38 This is a schematic front cross-sectional view of the elastic wave device according to the fourteenth embodiment.

[0282] The difference between this embodiment and the first embodiment is that the sound reflecting part is a sound reflecting membrane 118. Another difference is that the support member 113 only includes a support substrate. Apart from the above points, the elastic wave device of this embodiment is constructed in the same way as the elastic wave device 10 of the first embodiment.

[0283] An acoustic reflective membrane 118 is provided on the surface of the support member 113. A piezoelectric layer 4 is provided on the acoustic reflective membrane 118. In addition, the support member 113 and the piezoelectric layer 4 can be arranged such that at least a portion of the support member 113 and at least a portion of the piezoelectric layer 4 sandwich the acoustic reflective membrane 118 and are placed opposite each other.

[0284] The acoustic reflector 118 is a stack of multiple acoustic impedance layers. Specifically, the acoustic reflector 118 has multiple low acoustic impedance layers and multiple high acoustic impedance layers. The low acoustic impedance layers are layers with relatively low acoustic impedance. More specifically, the multiple low acoustic impedance layers in the acoustic reflector 118 are low acoustic impedance layer 115a, low acoustic impedance layer 115b, and low acoustic impedance layer 115c.

[0285] On the other hand, the high acoustic impedance layer is a layer with relatively high acoustic impedance. More specifically, the multiple high acoustic impedance layers in the acoustic reflective film 118 are high acoustic impedance layer 116a and high acoustic impedance layer 116b. Low acoustic impedance layers and high acoustic impedance layers are stacked alternately. In addition, the low acoustic impedance layer 115a is the layer located on the side closest to the piezoelectric layer 4 in the acoustic reflective film 118.

[0286] The acoustic reflector 118 has three low acoustic impedance layers and two high acoustic impedance layers. However, the acoustic reflector 118 may have at least one low acoustic impedance layer and one high acoustic impedance layer, respectively.

[0287] Materials used as low acoustic impedance layers include, for example, silicon oxide or aluminum. Materials used as high acoustic impedance layers include, for example, metals such as platinum or tungsten, and dielectrics such as aluminum nitride, silicon nitride, or hafnium oxide.

[0288] In this embodiment, similar to the first embodiment, unwanted waves can be effectively suppressed, and the degradation of filter characteristics can be effectively suppressed. Furthermore, by providing the acoustic reflection membrane 118, the energy of the elastic wave can be effectively sealed into the piezoelectric layer 4.

[0289] The acoustic reflector in this embodiment is the acoustic reflector membrane 118, and the structure of this invention can be applied to structures other than those in this embodiment.

[0290] The following uses Figure 39 The illustrated reference example shows a preferred structure of the present invention. The reference example differs from the first embodiment in that, instead of... Figure 2 The functional electrode 1 shown is provided with an IDT electrode 201. The difference between the reference example and the first embodiment is that the piezoelectric layer 204 does not have a through-hole. Apart from the above points, the elastic wave device of the reference example has the same structure as the first embodiment.

[0291] Furthermore, the IDT electrode 201 differs from the functional electrode in that it does not have a third electrode. Therefore, the IDT electrode 201 has a first comb electrode 7 and a second comb electrode 8. The intersection region E in the reference example is the region where adjacent first electrode fingers 15 and second electrode fingers 16 overlap when viewed from the orthogonal direction of the electrode fingers.

[0292] In the elastic wave device of the reference example, similar to the first to fourteenth embodiments, a thickness shear mode bulk wave is utilized. In this case, the portion provided with a pair of adjacent electrodes connected to different potentials functions as a resonator. Therefore, the structure of the elastic wave device utilizing the thickness shear mode bulk wave is equivalent to a structure in which multiple resonators are connected in parallel. In this respect, it is the same for both elastic wave devices with IDT electrodes and acoustic coupling type filters such as those in the first to fourteenth embodiments. Therefore, it can be said that the following structure shown in the reference example is also a preferred structure in the first to fourteenth embodiments.

[0293] In this invention, when the thickness of the piezoelectric layer is set to d and the center-to-center distance between adjacent electrodes is set to p, it is preferable that d / p is 0.5 or less, and more preferably 0.24 or less. This allows for appropriate excitation of the thickness shear mode bulk wave and sufficiently increases the fractional bandwidth of the elastic wave device. When the resonant frequency is set to fr and the anti-resonant frequency is set to fa, the fractional bandwidth is represented by (|fa-fr| / fr)×100 [%].

[0294] Figure 40 This is a graph showing the relationship between d / p and the fractional bandwidth of the elastic wave device in the reference example.

[0295] according to Figure 40 It can be seen that when d / p > 0.5, the fractional bandwidth is less than 5%. Conversely, when d / p ≤ 0.5, the fractional bandwidth can be increased to 5% or more. Therefore, the electromechanical coupling coefficient of the bulk wave in the thickness shear mode can be increased. When d / p ≤ 0.24 or less, the fractional bandwidth can be increased to 7% or more. Therefore, the electromechanical coupling coefficient of the bulk wave in the thickness shear mode can be effectively increased.

[0296] When the metallization rate of the electrode fingers relative to the excitation region C is set as MR, it is preferable to satisfy MR ≤ 1.75 (d / p) + 0.075. In this case, the fractional bandwidth of the elastic wave device will not become too large, and spurious emissions between the resonant frequency and the anti-resonant frequency can be suppressed. The details are shown below.

[0297] In this specification, the metallization rate MR of the electrode finger relative to the excitation region C refers to the proportion of the piezoelectric layer covered by the metal constituting the electrode finger within the excitation region C, viewed from above. Figure 39 In the reference example shown, the ratio of the area of ​​the first electrode finger 15 and the second electrode finger 16 within the excitation region C when viewed from above to the area of ​​the excitation region C is called the metallization rate MR. On the other hand, in Figure 2In the first embodiment of the present invention shown, the ratio of the area of ​​the first electrode finger 15 and the third electrode finger 17 to the excitation region C and the ratio of the area of ​​the second electrode finger 16 and the third electrode finger 17 to the excitation region C are called the metallization rate MR.

[0298] Furthermore, when the width of the electrode fingers located within the excitation region C is fixed, the metallization rate MR can also be calculated by dividing the total width of the electrode fingers located within the excitation region C by the size of the excitation region C along the orthogonal direction of the electrode fingers.

[0299] Figure 41 This is a graph showing the relationship between the fractional bandwidth and the normalized spurious magnitude in the elastic wave apparatus of the reference example. Figure 41 The diagram shows the results obtained by measuring the stray phase rotation amount each time the fractional bandwidth is changed by varying the thickness of the piezoelectric layer and the size of the electrode fingers. Specifically, Figure 41 The normalized spurious magnitude is the value of the spurious impedance phase rotation normalized by 180°. Figure 41 The results shown are for the case where a piezoelectric layer of LiNbO3 with Z-cut is used, but the same trend is observed even when using piezoelectric layers with other cut angles.

[0300] exist Figure 41 In the region enclosed by ellipse B, the normalized spurious magnitude between the resonant frequency and the anti-resonant frequency is 1.0. When the fractional bandwidth of the elastic wave resonator exceeds 17%, the normalized spurious magnitude may become greater than 1.0. Therefore, the fractional bandwidth is preferably less than 17%. This suppresses spurious emissions between the resonant frequency and the anti-resonant frequency.

[0301] Figure 42 This is a graph showing the relationship between d / p, metallization ratio (MR), and fractional bandwidth. Figure 42 The figure shows the results of calculating the fractional bandwidth each time the d / p and metallization rate MR are different.

[0302] exist Figure 42 In the diagram, the shaded area represents the region with a fractional bandwidth of 17% or less. The boundary between the shaded and unshaded areas is approximately represented by a dashed line G. The dashed line G is represented by MR = 1.75 (d / p) + 0.075. Furthermore, in the reference example, when MR ≤ 1.75 (d / p) + 0.075, it is easy to achieve a fractional bandwidth of 17% or less, making it easier to suppress spurious emissions. Therefore, in this invention, MR ≤ 1.75 (d / p) + 0.075 is preferred. This facilitates the suppression of spurious emissions.

[0303] On the other hand, through Figure 42The dashed line G1 in the diagram shows that the slope of the change in metallization rate MR relative to the change in d / p is the same as that of the dashed line G, and the boundary where the fractional bandwidth becomes 17% or less over the entire range. The dashed line G1 is represented by MR = 1.75(d / p) + 0.05. Moreover, when MR ≤ 1.75(d / p) + 0.05, the fractional bandwidth can be made to be 17% or less more reliably, and spurious emissions can be suppressed more reliably. Therefore, in this invention, MR ≤ 1.75(d / p) + 0.05 is more preferable. As a result, spurious emissions can be suppressed more reliably.

[0304] Here, the relationship between the fractional bandwidth of the elastic wave device 10 and the Euler angles (φ, θ, ψ) at the piezoelectric portion of the piezoelectric layer 4 is derived in the structure of the first embodiment, where d / p is infinitely close to 0. Furthermore, φ in the Euler angles is 0°.

[0305] Figure 43 This is a graph showing the mapping of the fractional bandwidth relative to the Euler angles (0°, θ, ψ) of LiNbO3 when d / p is infinitely close to 0. Figure 43 The shaded area indicates the region with a fractional bandwidth of at least 5%, and when approximating the range of this region, it becomes the range represented by the following equations (1), (2) and (3).

[0306] (Within the range of 0°±10°, 0°~25°, any ψ) … Equation (1)

[0307] (Within the range of 0°±10°, 25°~100°, 0°~75° [(1-(θ-50)]) 2 / 2500)] 1 / 2 Or 180°-75° [(1-(θ-50)] 2 / 2500)] 1 / 2 ~180°) …Equation (2)

[0308] (Within the range of 0°±10°, 180°-40°[(1-(ψ-90]) 2 / 8100)] 1 / 2 ~180°, any ψ) …Equation (3)

[0309] In this invention, the Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric layer are preferably within the range of Equations (1), (2), or (3) above. This allows for a sufficiently widened fractional bandwidth of the elastic wave resonator. The same applies when the piezoelectric layer includes lithium tantalate.

[0310] Hereinafter, examples of the manner in which the elastic wave device according to the present invention is described are summarized.

[0311] <1> An elastic wave device comprising: a piezoelectric layer having a first main surface and a second main surface facing each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers connected at one end to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, the plurality of second electrode fingers interleaved with the plurality of first electrode fingers; and a third electrode having a plurality of third electrode fingers and at least one third busbar, the plurality of third electrode fingers being disposed on one of the first main surface and the second main surface of the piezoelectric layer such that, when viewed from above, they are arranged side by side with the first electrode fingers and the second electrode fingers in the direction in which the first electrode fingers and the second electrode fingers are arranged, the at least one third busbar connecting the plurality of third electrode fingers to each other, and the third electrode being connected to a potential different from that of the first comb-shaped electrode and the second comb-shaped electrode, the first comb-shaped electrode and the second comb-shaped electrode... One of the electrodes is connected to the input potential, and the other of the first comb electrode and the second comb electrode is connected to the output potential. The order of the first electrode finger, the second electrode finger, and the third electrode finger is the order of the first electrode finger, the second electrode finger, and the third electrode finger as a cycle, starting from the first electrode finger. When the direction orthogonal to the extension direction of the first electrode finger, the second electrode finger, and the third electrode finger is defined as the electrode finger orthogonal direction, the area where the first electrode finger and the second electrode finger overlap in the electrode finger orthogonal direction is the intersection area. In top view, a third bus bar is located between the intersection area and the first bus bar. The third bus bar overlaps with the plurality of first electrode fingers in top view. The third bus bar is electrically insulated from the plurality of first electrode fingers. At least a portion of the portion of the piezoelectric layer located between the intersection area and the first bus bar and located between the first comb electrode and the third electrode in the electrode finger orthogonal direction is provided with a through hole.

[0312] <2> According to the elastic wave device described in <1>, wherein,

[0313] The through hole is provided in the portion of the piezoelectric layer located between the intersection region and the first busbar, and in the orthogonal direction of the electrode fingers between the first electrode finger and the third electrode finger.

[0314] <3> According to the elastic wave device described in <1> or <2>, wherein,

[0315] The third busbar includes a common connection portion that connects an adjacent pair of third electrode fingers to each other. The common connection portion has a portion adjacent to the first electrode finger in the orthogonal direction of the electrode fingers. The through hole is provided in a portion of the piezoelectric layer located between the cross region and the first busbar and between the first electrode finger and the common connection portion in the orthogonal direction of the electrode fingers.

[0316] <4> According to any one of <1> to <3>, the elastic wave device, wherein,

[0317] The elastic wave device includes two third busbars. In top view, one third busbar is located between the intersection region and the first busbar, overlapping with the plurality of first electrode fingers. This third busbar is electrically insulated from the plurality of first electrode fingers. In top view, the other third busbar is located between the intersection region and the second busbar, overlapping with the plurality of second electrode fingers. This third busbar is electrically insulated from the plurality of second electrode fingers. At least a portion of the portion of the piezoelectric layer located between the intersection region and the second busbar, and in the orthogonal direction of the electrode fingers between the second comb electrode and the third electrode, is provided with a through hole.

[0318] <5> According to any one of <1> to <3>, the elastic wave device, wherein,

[0319] The elastic wave device includes two third busbars. In top view, one third busbar is located between the intersection region and the first busbar, and this third busbar overlaps with the plurality of first electrode fingers in top view. This third busbar is electrically insulated from the plurality of first electrode fingers. In top view, a second busbar is located between the intersection region and the other third busbar, and this second busbar overlaps with the plurality of third electrode fingers in top view. This second busbar is electrically insulated from the plurality of third electrode fingers. At least a portion of the portion of the piezoelectric layer located between the intersection region and the third busbar, and in the orthogonal direction of the electrode fingers between the second comb electrode and the third electrode, is provided with a through hole.

[0320] <6> According to any one of <1> to <5>, the elastic wave device, wherein,

[0321] A through hole is provided in the portion between the third busbar and the first busbar, which overlap with the plurality of first electrode fingers when viewed from above.

[0322] <7> According to any one of <1> to <6>, the elastic wave device, wherein,

[0323] The plurality of third electrode fingers and the third busbar are disposed on the first main surface of the piezoelectric layer, and the elastic wave device further comprises an insulating layer disposed on the first main surface of the piezoelectric layer, wherein a portion of the plurality of first electrode fingers and a portion of the third busbar intersect across the insulating layer.

[0324] <8> According to any one of <1> to <6>, the elastic wave device, wherein,

[0325] The plurality of third electrode fingers and the third bus bar are disposed on the first main surface of the piezoelectric layer. The elastic wave device further includes an insulating layer disposed on the first main surface of the piezoelectric layer. A portion of the plurality of first electrode fingers and a portion of the third bus bar intersect across the insulating layer. The first electrode fingers, the insulating layer and the third bus bar are stacked in sequence.

[0326] <9> An elastic wave device comprising: a piezoelectric layer having a first main surface and a second main surface facing each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers connected at one end to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, the plurality of second electrode fingers interleaved with the plurality of first electrode fingers; and a third electrode having a plurality of third electrode fingers and at least one third busbar, the plurality of third electrode fingers being disposed on one of the first main surface and the second main surface of the piezoelectric layer such that, when viewed from above, they are arranged side by side with the first electrode fingers and the second electrode fingers in the direction in which the first electrode fingers and the second electrode fingers are arranged, the at least one third busbar connecting the plurality of third electrode fingers to each other, and the third electrode being connected to a potential different from that of the first comb-shaped electrode and the second comb-shaped electrode, the first comb-shaped electrode and the second comb-shaped electrode... One of the first and second comb electrodes is connected to the input potential, and the other of the first and second comb electrodes is connected to the output potential. The order of the first, second, and third electrode fingers is such that, starting from the first electrode finger, the first, second, and third electrode fingers are arranged in a cycle. When the direction orthogonal to the extension direction of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the area where the first and second electrode fingers overlap in the electrode finger orthogonal direction is a cross region. In top view, the first busbar is located between the cross region and one of the third busbars. The first busbar overlaps with the plurality of third electrode fingers in top view. The first busbar is electrically insulated from the plurality of third electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the first busbar and located between the first comb electrode and the third electrode in the electrode finger orthogonal direction is provided with a through hole.

[0327] <10> According to the elastic wave device described in <9>, wherein,

[0328] The elastic wave device includes two third busbars. In top view, the first busbar is located between the intersection region and one of the third busbars, and overlaps with the plurality of third electrode fingers in top view. The first busbar is electrically insulated from the plurality of third electrode fingers. In top view, the second busbar is located between the intersection region and another of the third busbars, and overlaps with the plurality of third electrode fingers in top view. The second busbar is electrically insulated from the plurality of third electrode fingers. At least a portion of the portion of the piezoelectric layer located between the intersection region and the second busbar, and in the orthogonal direction of the electrode fingers between the second comb electrode and the third electrode, is provided with a through hole.

[0329] <11> According to the elastic wave device described in <9> or <10>, wherein,

[0330] Through holes are provided between the portions of the plurality of third electrode fingers located between the third busbar and the first busbar, which are configured to sandwich the first busbar together with the intersection region.

[0331] <12> The elastic wave device described in any one of <1> to <6> or <9> to <11>, wherein,

[0332] The plurality of third electrodes refer to the third busbar disposed on the second main surface of the piezoelectric layer.

[0333] <13> An elastic wave device comprising: a piezoelectric layer having a first main surface and a second main surface facing each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers connected at one end to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, the plurality of second electrode fingers interleaved with the plurality of first electrode fingers; and a third electrode having a plurality of The piezoelectric layer comprises a third electrode, multiple connecting electrodes, and at least one third busbar. The multiple third electrode fingers are respectively disposed on the first main surface of the piezoelectric layer, such that, when viewed from above, they are arranged side-by-side with the first and second electrode fingers in the direction in which the first and second electrode fingers are arranged. The multiple connecting electrodes penetrate the piezoelectric layer and are respectively connected to the multiple third electrode fingers. The at least one third busbar is disposed on the second main surface and is electrically connected to the multiple third electrode fingers through the multiple connecting electrodes. Furthermore, the third electrode is different from the first... The comb-shaped electrode and the second comb-shaped electrode are connected at potentials. One of the first comb-shaped electrode and the second comb-shaped electrode is connected to the input potential, and the other of the first comb-shaped electrode and the second comb-shaped electrode is connected to the output potential. The first electrode finger, the second electrode finger, and the third electrode finger are arranged in a cycle starting from the first electrode finger. When the direction orthogonal to the extension direction of the first electrode finger, the second electrode finger, and the third electrode finger is defined as the electrode finger orthogonal direction, the area where the first electrode finger and the second electrode finger overlap in the electrode finger orthogonal direction is a cross region. In top view, a third bus bar is located between the cross region and the first bus bar. The third bus bar overlaps with the plurality of first electrode fingers in top view. At least a portion of the portion of the piezoelectric layer located between the cross region and the first bus bar and located between the first electrode finger and the third electrode finger in the electrode finger orthogonal direction is provided with a through hole.

[0334] <14> An elastic wave device comprising: a piezoelectric layer having a first main surface and a second main surface facing each other; a first comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a first busbar and a plurality of first electrode fingers connected at one end to the first busbar; a second comb-shaped electrode disposed on the first main surface of the piezoelectric layer, having a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, the plurality of second electrode fingers interleaved with the plurality of first electrode fingers; and a third electrode having a plurality of third electrode fingers disposed on the first main surface of the piezoelectric layer such that, when viewed from above, they are arranged side by side with the first electrode fingers and the second electrode fingers in the direction in which the first electrode fingers and the second electrode fingers are arranged, the third electrode having a plurality of connecting electrodes connected to the plurality of third electrode fingers respectively, and a third busbar electrically connected to the plurality of third electrode fingers through the plurality of connecting electrodes, and the third electrode having a potential connection different from that of the first comb-shaped electrode and the second comb-shaped electrode. The first comb electrode and the second comb electrode are connected to the input potential, and the other comb electrode is connected to the output potential. The first electrode finger, the second electrode finger, and the third electrode finger are arranged in a cycle starting from the first electrode finger. When the direction orthogonal to the extension direction of the first electrode finger, the second electrode finger, and the third electrode finger are defined as the electrode finger orthogonal direction, the area where the first electrode finger and the second electrode finger overlap in the electrode finger orthogonal direction is the intersection area. In top view, a third bus bar is located between the intersection area and the first bus bar. The third bus bar overlaps with the plurality of first electrode fingers in top view. At least a portion of the portion of the piezoelectric layer located between the intersection area and the first bus bar and located between the first electrode finger and the third electrode finger in the electrode finger orthogonal direction is provided with a through hole.

[0335] <15> According to the elastic wave device described in <14>, wherein,

[0336] The elastic wave device further comprises: a support body disposed on the first main surface of the piezoelectric layer; and a cover member disposed on the support body, having a third main surface located on the piezoelectric layer side and a fourth main surface facing the third main surface, the third busbar being disposed on the third main surface of the cover member such that it faces a portion of the plurality of third electrode fingers, the plurality of connecting electrodes being disposed at least on the plurality of third electrode fingers, connecting the plurality of third electrode fingers to the third busbar.

[0337] <16> According to the elastic wave device described in <14>, wherein,

[0338] The elastic wave device also includes:

[0339] Multiple conductive bonding members disposed on the first main surface of the piezoelectric layer; and

[0340] A mounting substrate, which is bonded to the piezoelectric layer via the plurality of conductive bonding members, has a fifth main surface located on the side of the piezoelectric layer and a sixth main surface opposite to the fifth main surface.

[0341] The third busbar is disposed on the fifth main surface of the mounting substrate, such that it is opposite to a portion of the plurality of third electrode fingers, and the plurality of connecting electrodes are disposed at least on the plurality of third electrode fingers, connecting the third busbar to the plurality of third electrode fingers.

[0342] <17> According to any one of <1> to <16>, the elastic wave device, wherein,

[0343] The first comb-shaped electrode is connected to the input potential, and the second comb-shaped electrode is connected to the output potential.

[0344] <18> According to any one of <1> to <16>, the elastic wave device, wherein,

[0345] The first comb-shaped electrode is connected to the output potential, and the second comb-shaped electrode is connected to the input potential.

[0346] <19> According to any one of <1> to <18>, the elastic wave device, wherein,

[0347] The elastic wave device further includes a support member stacked on the piezoelectric layer. In a top view, an acoustic reflector is formed at the position in the support member where it overlaps with the plurality of first electrode fingers, the plurality of second electrode fingers, and the plurality of third electrode fingers. When the longest distance among the center-to-center distances of adjacent first electrode fingers and third electrode fingers and adjacent second electrode fingers and third electrode fingers is set as p, and when the thickness of the piezoelectric layer is set as d, d / p is 0.5 or less.

[0348] <20> According to the elastic wave device described in <19>, wherein,

[0349] d / p is below 0.24.

[0350] <21> According to the elastic wave device described in <19> or <20>, wherein,

[0351] The acoustic reflection portion is a cavity, and the support member and the piezoelectric layer are configured such that a portion of the support member and a portion of the piezoelectric layer sandwich the cavity and are opposite to each other.

[0352] <22> According to the elastic wave device described in <19> or <20>, wherein,

[0353] The acoustic reflector is an acoustic reflector membrane comprising a high acoustic impedance layer with relatively high acoustic impedance and a low acoustic impedance layer with relatively low acoustic impedance. The support member and the piezoelectric layer are configured such that at least a portion of the support member and at least a portion of the piezoelectric layer sandwich the acoustic reflector membrane and are opposite to each other.

[0354] <23> According to any one of <19> to <22>, the elastic wave device, wherein,

[0355] When the direction orthogonal to the extension direction of the first electrode finger, the second electrode finger, and the third electrode finger is defined as the electrode finger orthogonal direction, the regions where adjacent first electrode fingers and third electrode fingers overlap in the electrode finger orthogonal direction and the regions between the centers of adjacent first electrode fingers and third electrode fingers, and the regions where adjacent second electrode fingers and third electrode fingers overlap in the electrode finger orthogonal direction and the regions between the centers of adjacent second electrode fingers and third electrode fingers are the excitation regions. When the metallization rate of the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger relative to the excitation region is defined as MR, MR ≤ 1.75 (d / p) + 0.075 is satisfied.

[0356] <24> According to any one of <1> to <23>, the elastic wave device, wherein,

[0357] The piezoelectric layer includes lithium niobate.

[0358] The Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric layer are within the range of the following equations (1), (2), or (3).

[0359] (Within the range of 0°±10°, 0°~25°, any ψ) … Equation (1)

[0360] (Within the range of 0°±10°, 25°~100°, 0°~75° [(1-(θ-50)]) 2 / 2500)] 1 / 2 Or 180°-75° [(1-(θ-50)] 2 / 2500)] 1 / 2 ~180°) …Equation (2)

[0361] (Within the range of 0°±10°, 180°-40°[(1-(ψ-90]) 2 / 8100)] 1 / 2 ~180°, any ψ) … Equation (3).

[0362] Explanation of reference numerals in the attached figures

[0363] 1…functional electrode;

[0364] 2, 2L… piezoelectric substrate;

[0365] 3…supporting components;

[0366] 4. 4A~4O… piezoelectric layer;

[0367] 4a, 4b... First main face, second main face;

[0368] 4c…through hole;

[0369] 5…Insulation layer;

[0370] 6...support base plate;

[0371] 7, 8… First comb electrode, second comb electrode;

[0372] 9…Third electrode;

[0373] 10…elastic wave device;

[0374] 10a…cavity section;

[0375] 12~14…First busbar to third busbar;

[0376] 14a…Shared connection part;

[0377] 14b…section;

[0378] 15~17… First electrode fingers~Third electrode fingers;

[0379] 19…insulator layer;

[0380] 21…functional electrodes;

[0381] 24…Third busbar;

[0382] 29…Third electrode;

[0383] 31, 41A… Functional electrodes;

[0384] 44A, 44B… Third busbar;

[0385] 49…Third electrode;

[0386] 50a…cavity section;

[0387] 51…functional electrode;

[0388] 53…supporting components;

[0389] 54A, 54B… Third busbar;

[0390] 54a…Shared connection part;

[0391] 54b…section;

[0392] 55, 56… First electrode finger, second electrode finger;

[0393] 57, 58… First comb electrode, second comb electrode;

[0394] 59…Third electrode;

[0395] 62…dielectric layer;

[0396] 70a…cavity section;

[0397] 75…Insulation layer;

[0398] 78… connect electrodes;

[0399] 79…Third electrode;

[0400] 80…elastic wave device;

[0401] 81…functional electrode;

[0402] 82…First support body;

[0403] 82a…opening;

[0404] 83…Second support body;

[0405] 84… Cover components;

[0406] 84A…Cover component main body;

[0407] 84B…inorganic oxide layer;

[0408] 84a, 84b... Third principal face, fourth principal face;

[0409] 85…through electrode;

[0410] 86…external terminal;

[0411] 87…bumps;

[0412] 88… connects the electrodes;

[0413] 89…Third electrode;

[0414] 90…elastic wave device;

[0415] 94…sealing resin;

[0416] 95… Mounting substrate;

[0417] 95a, 95b... Fifth principal face, sixth principal face;

[0418] 96…external terminal;

[0419] 97…bumps;

[0420] 98…electrode pads;

[0421] 113…supporting components;

[0422] 115a~115c…low acoustic impedance layer;

[0423] 116a, 116b… high acoustic impedance layers;

[0424] 118…acoustic reflective membrane;

[0425] 201…IDT electrode;

[0426] 204…piezoelectric layer;

[0427] C…incentive region;

[0428] E…intersection area;

[0429] F… Element electrode forming section.

Claims

1. An elastic wave device, comprising: A piezoelectric layer having a first principal surface and a second principal surface that are opposite to each other; A first comb-shaped electrode is disposed on the first main surface of the piezoelectric layer and has a first busbar and a plurality of first electrode fingers, one end of which is connected to the first busbar. The second comb-shaped electrode is disposed on the first main surface of the piezoelectric layer, and has a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, wherein the plurality of second electrode fingers and the plurality of first electrode fingers are interleaved and interlocked. as well as The third electrode has a plurality of third electrode fingers and at least one third busbar. The plurality of third electrode fingers are respectively disposed on one of the first main surface and the second main surface of the piezoelectric layer, such that, when viewed from above, they are arranged side by side with the first and second electrode fingers in the direction in which the first and second electrode fingers are arranged. The at least one third busbar connects the plurality of third electrode fingers to each other, and the third electrode is connected to a potential different from that of the first comb electrode and the second comb electrode. One of the first comb electrode and the second comb electrode is connected to the input potential, and the other of the first comb electrode and the second comb electrode is connected to the output potential. The order in which the first electrode finger, the second electrode finger, and the third electrode finger are arranged is such that, starting with the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger are arranged as a cycle. When the direction orthogonal to the extending directions of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the area where the first and second electrode fingers overlap in the electrode finger orthogonal direction is the intersection region. From a top view, one of the third busbars is located between the intersection area and the first busbar. This third busbar overlaps with the plurality of first electrode fingers in the top view, and the third busbar is electrically insulated from the plurality of first electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the first busbar, and located between the first comb electrode and the third electrode in the orthogonal direction of the electrode pointer, is provided with a through hole.

2. The elastic wave device according to claim 1, wherein, The through hole is provided in the portion of the piezoelectric layer located between the intersection region and the first busbar, and in the orthogonal direction of the electrode fingers between the first electrode finger and the third electrode finger.

3. The elastic wave device according to claim 1 or 2, wherein, The third busbar includes a common connection portion that connects an adjacent pair of third electrode fingers to each other, the common connection portion having a portion adjacent to the first electrode finger in the orthogonal direction of the electrode fingers. The through hole is provided in the portion of the piezoelectric layer located between the cross region and the first busbar, and in the orthogonal direction of the electrode fingers between the first electrode finger and the common connection portion.

4. The elastic wave device according to any one of claims 1 to 3, wherein, The elastic wave device includes two of the third busbars. From a top view, one of the third busbars is located between the intersection area and the first busbar. This third busbar overlaps with the plurality of first electrode fingers in the top view, and is electrically insulated from the plurality of first electrode fingers. From a top view, another third busbar is located between the intersection region and the second busbar. This third busbar overlaps with the plurality of second electrode fingers from a top view, and the third busbar is electrically insulated from the plurality of second electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the second busbar, and located between the second comb electrode and the third electrode in the orthogonal direction of the electrode pointer, is provided with a through hole.

5. The elastic wave device according to any one of claims 1 to 3, wherein, The elastic wave device includes two of the third busbars. From a top view, one of the third busbars is located between the intersection area and the first busbar. This third busbar overlaps with the plurality of first electrode fingers in the top view, and is electrically insulated from the plurality of first electrode fingers. From a top view, the second busbar is located between the intersection area and another third busbar, and the second busbar overlaps with the plurality of third electrode fingers in the top view. The second busbar is electrically insulated from the plurality of third electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the third busbar, and located between the second comb electrode and the third electrode in the orthogonal direction of the electrode pointer, is provided with a through hole.

6. The elastic wave device according to any one of claims 1 to 5, wherein, A through hole is provided in the portion between the third busbar and the first busbar, which overlap with the plurality of first electrode fingers when viewed from above.

7. The elastic wave device according to any one of claims 1 to 6, wherein, The plurality of third electrodes refer to the third busbars disposed on the first main surface of the piezoelectric layer. The elastic wave device further includes an insulating layer disposed on the first main surface of the piezoelectric layer. A portion of the plurality of first electrode fingers and a portion of one of the third busbars intersect across the insulating layer.

8. The elastic wave device according to any one of claims 1 to 6, wherein, The plurality of third electrodes refer to the third busbars disposed on the first main surface of the piezoelectric layer. The elastic wave device further includes an insulating layer disposed on the first main surface of the piezoelectric layer. A portion of the plurality of first electrode fingers and a portion of one of the third busbars intersect across the insulating layer. The first electrode finger, the insulating layer, and the third busbar are stacked in sequence.

9. An elastic wave device, comprising: A piezoelectric layer having a first principal surface and a second principal surface that are opposite to each other; A first comb-shaped electrode is disposed on the first main surface of the piezoelectric layer and has a first busbar and a plurality of first electrode fingers, one end of which is connected to the first busbar. The second comb-shaped electrode is disposed on the first main surface of the piezoelectric layer, and has a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, wherein the plurality of second electrode fingers and the plurality of first electrode fingers are interleaved and interlocked. as well as The third electrode has a plurality of third electrode fingers and at least one third busbar. The plurality of third electrode fingers are respectively disposed on one of the first main surface and the second main surface of the piezoelectric layer, such that, when viewed from above, they are arranged side by side with the first and second electrode fingers in the direction in which the first and second electrode fingers are arranged. The at least one third busbar connects the plurality of third electrode fingers to each other, and the third electrode is connected to a potential different from that of the first comb electrode and the second comb electrode. One of the first comb electrode and the second comb electrode is connected to the input potential, and the other of the first comb electrode and the second comb electrode is connected to the output potential. The order in which the first electrode finger, the second electrode finger, and the third electrode finger are arranged is such that, starting with the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger are arranged as a cycle. When the direction orthogonal to the extending directions of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the area where the first and second electrode fingers overlap in the electrode finger orthogonal direction is the intersection region. From a top view, the first busbar is located between the intersection area and one of the third busbars. The first busbar overlaps with the plurality of third electrode fingers from a top view. The first busbar is electrically insulated from the plurality of third electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the first busbar, and located between the first comb electrode and the third electrode in the orthogonal direction of the electrode pointer, is provided with a through hole.

10. The elastic wave device according to claim 9, wherein, The elastic wave device includes two of the third busbars. From a top view, the first busbar is located between the intersection area and one of the third busbars. The first busbar overlaps with the plurality of third electrode fingers from a top view perspective. The first busbar is electrically insulated from the plurality of third electrode fingers. From a top view, the second busbar is located between the intersection area and another third busbar, and the second busbar overlaps with the plurality of third electrode fingers in the top view. The second busbar is electrically insulated from the plurality of third electrode fingers. At least a portion of the portion of the piezoelectric layer located between the cross region and the second busbar, and located between the second comb electrode and the third electrode in the orthogonal direction of the electrode pointer, is provided with a through hole.

11. The elastic wave device according to claim 9 or 10, wherein, Through holes are provided between the portions of the plurality of third electrode fingers located between the third busbar and the first busbar, which are configured to sandwich the first busbar together with the intersection region.

12. The elastic wave device according to any one of claims 1 to 6 or 9 to 11, wherein, The plurality of third electrodes refer to the third busbar disposed on the second main surface of the piezoelectric layer.

13. An elastic wave device, comprising: A piezoelectric layer having a first principal surface and a second principal surface that are opposite to each other; A first comb-shaped electrode is disposed on the first main surface of the piezoelectric layer and has a first busbar and a plurality of first electrode fingers, one end of which is connected to the first busbar. The second comb-shaped electrode is disposed on the first main surface of the piezoelectric layer, and has a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, wherein the plurality of second electrode fingers and the plurality of first electrode fingers are interleaved and interlocked. as well as The third electrode has multiple third electrode fingers, multiple connecting electrodes, and at least one third busbar. The multiple third electrode fingers are respectively disposed on the first main surface of the piezoelectric layer, such that, when viewed from above, they are arranged side-by-side with the first and second electrode fingers in the direction in which the first and second electrode fingers are arranged. The multiple connecting electrodes penetrate the piezoelectric layer and are respectively connected to the multiple third electrode fingers. The at least one third busbar is disposed on the second main surface and is electrically connected to the multiple third electrode fingers through the multiple connecting electrodes. Furthermore, the third electrode is connected to a potential different from that of the first comb-shaped electrode and the second comb-shaped electrode. One of the first comb electrode and the second comb electrode is connected to the input potential, and the other of the first comb electrode and the second comb electrode is connected to the output potential. The order in which the first electrode finger, the second electrode finger, and the third electrode finger are arranged is such that, starting with the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger are arranged as a cycle. When the direction orthogonal to the extending directions of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the area where the first and second electrode fingers overlap in the electrode finger orthogonal direction is the intersection region. When viewed from above, one of the third busbars is located between the intersection area and the first busbar, and this third busbar overlaps with the plurality of first electrode fingers when viewed from above. At least a portion of the portion of the piezoelectric layer located between the cross region and the first busbar, and located between the first electrode finger and the third electrode finger in the orthogonal direction of the electrode fingers, is provided with a through hole.

14. An elastic wave device, comprising: A piezoelectric layer having a first principal surface and a second principal surface that are opposite to each other; A first comb-shaped electrode is disposed on the first main surface of the piezoelectric layer and has a first busbar and a plurality of first electrode fingers, one end of which is connected to the first busbar. The second comb-shaped electrode is disposed on the first main surface of the piezoelectric layer, and has a second busbar and a plurality of second electrode fingers connected at one end to the second busbar, wherein the plurality of second electrode fingers and the plurality of first electrode fingers are interleaved and interlocked. as well as The third electrode has a plurality of third electrode fingers, which are respectively disposed on the first main surface of the piezoelectric layer, such that when viewed from above, they are arranged side by side with the first and second electrode fingers in the direction in which the first and second electrode fingers are arranged. The third electrode has a plurality of connecting electrodes respectively connected to the plurality of third electrode fingers, and a third busbar electrically connected to the plurality of third electrode fingers through the plurality of connecting electrodes. Furthermore, the third electrode is connected to a potential different from that of the first comb electrode and the second comb electrode. One of the first comb electrode and the second comb electrode is connected to the input potential, and the other of the first comb electrode and the second comb electrode is connected to the output potential. The order in which the first electrode finger, the second electrode finger, and the third electrode finger are arranged is such that, starting with the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger are arranged as a cycle. When the direction orthogonal to the extending directions of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the area where the first and second electrode fingers overlap in the electrode finger orthogonal direction is the intersection region. When viewed from above, one of the third busbars is located between the intersection area and the first busbar, and this third busbar overlaps with the plurality of first electrode fingers when viewed from above. At least a portion of the portion of the piezoelectric layer located between the cross region and the first busbar, and located between the first electrode finger and the third electrode finger in the orthogonal direction of the electrode fingers, is provided with a through hole.

15. The elastic wave device according to claim 14, wherein, The elastic wave device also includes: A support body disposed on the first main surface of the piezoelectric layer; and A cover member, disposed on the support body, has a third main surface located on the piezoelectric layer side and a fourth main surface opposite to the third main surface. The third busbar is disposed on the third main surface of the cover member, such that it is opposite to a portion of the plurality of third electrode fingers, and the plurality of connecting electrodes are disposed at least on the plurality of third electrode fingers, connecting the plurality of third electrode fingers to the third busbar.

16. The elastic wave device according to claim 14, wherein, The elastic wave device also includes: Multiple conductive bonding members are disposed on the first main surface of the piezoelectric layer; and A mounting substrate, which is bonded to the piezoelectric layer via the plurality of conductive bonding members, has a fifth main surface located on the side of the piezoelectric layer and a sixth main surface opposite to the fifth main surface. The third busbar is disposed on the fifth main surface of the mounting substrate, such that it is opposite to a portion of the plurality of third electrode fingers, and the plurality of connecting electrodes are disposed at least on the plurality of third electrode fingers, connecting the third busbar to the plurality of third electrode fingers.

17. The elastic wave device according to any one of claims 1 to 16, wherein, The first comb-shaped electrode is connected to the input potential, and the second comb-shaped electrode is connected to the output potential.

18. The elastic wave device according to any one of claims 1 to 16, wherein, The first comb-shaped electrode is connected to the output potential, and the second comb-shaped electrode is connected to the input potential.

19. The elastic wave device according to any one of claims 1 to 18, wherein, The elastic wave device also includes a support member stacked on the piezoelectric layer. From a top view, an acoustic reflector is formed at the position in the support member where it overlaps with the plurality of first electrode fingers, the plurality of second electrode fingers, and the plurality of third electrode fingers. When p is set as the longest distance among the center-to-center distances of adjacent first electrode fingers and third electrode fingers and adjacent second electrode fingers and third electrode fingers, and when d is set as the thickness of the piezoelectric layer, d / p is 0.5 or less.

20. The elastic wave device according to claim 19, wherein, d / p is below 0.

24.

21. The elastic wave device according to claim 19 or 20, wherein, The acoustic reflection portion is a cavity, and the support member and the piezoelectric layer are configured such that a portion of the support member and a portion of the piezoelectric layer sandwich the cavity and are opposite to each other.

22. The elastic wave device according to claim 19 or 20, wherein, The acoustic reflector is an acoustic reflector membrane comprising a high acoustic impedance layer with relatively high acoustic impedance and a low acoustic impedance layer with relatively low acoustic impedance. The support member and the piezoelectric layer are configured such that at least a portion of the support member and at least a portion of the piezoelectric layer sandwich the acoustic reflector membrane and are opposite to each other.

23. The elastic wave device according to any one of claims 19 to 22, wherein, When the direction orthogonal to the extending directions of the first, second, and third electrode fingers is defined as the electrode finger orthogonal direction, the regions where adjacent first and third electrode fingers overlap in the electrode finger orthogonal direction and the regions between the centers of adjacent first and third electrode fingers, and the regions where adjacent second and third electrode fingers overlap in the electrode finger orthogonal direction and the regions between the centers of adjacent second and third electrode fingers, are the excitation regions. When the metallization rate of the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger relative to the excitation region is set as MR, MR ≤ 1.75 (d / p) + 0.075 is satisfied.

24. The elastic wave device according to any one of claims 1 to 23, wherein, The piezoelectric layer includes lithium niobate. The Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric layer are within the range of the following equations (1), (2), or (3). (Within the range of 0°±10°, 0°~25°, any ψ) … Equation (1) (Within the range of 0°±10°, 25°~100°, 0°~75° [(1-(θ-50)]) 2 / 2500)] 1 / 2 Or 180°-75° [(1-(θ-50)] 2 / 2500)] 1 / 2 ~180°) …Equation (2) (Within the range of 0°±10°, 180°-40°[(1-(ψ-90]) 2 / 8100)] 1 / 2 ~180°, any ψ) … Equation (3).

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