Elastic wave device

Abstract

The invention provides an elastic wave device which can promote miniaturization of a filter device and can improve power resistance. This elastic wave device (10) is provided with a first elastic wave resonator (10A) and a second elastic wave resonator (10B). Each of the first elastic wave resonator (10A) and the second elastic wave resonator (10B) includes: a piezoelectric film including a piezoelectric layer (14) including lithium niobate; a first comb electrode (a first comb electrode, a fourth comb electrode) provided on the piezoelectric layer (14), having a first bus bar (a first bus bar (22), a fourth bus bar (32)) and a plurality of first electrode fingers (a plurality of first electrode fingers (25), a plurality of fourth electrode fingers (35)) each having one end connected to the first bus bar, and connected to an input potential; a second comb electrode (a second comb electrode, a fifth comb electrode) provided on the piezoelectric layer (14), having a second bus bar (a second bus bar (23), a fifth bus bar (33)) and a plurality of second electrode fingers (a plurality of second electrode fingers (26), a plurality of fifth electrode fingers (36)) each having one end connected to the second bus bar and interleaved with the plurality of first electrode fingers (25), a plurality of fourth electrode fingers (35)), and connected to the output potential; and a third electrode having a plurality of third electrode fingers (a plurality of third electrode fingers (27) and a plurality of sixth electrode fingers (37)) provided on the piezoelectric layer (14) so as to be aligned 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 aligned in plan view, and connection electrodes (a third bus bar (24) and a sixth bus bar (34)) that connect adjacent third electrode fingers to each other. And connecting with a reference potential. In each of the first elastic wave resonator (10A) and the second elastic wave resonator (10B), the order in which the first electrode fingers, the second electrode fingers, and the third electrode fingers are arranged in plan view is an order in which the first electrode fingers, the third electrode fingers, the second electrode fingers, and the third electrode fingers are arranged as one cycle from the first electrode fingers. Each of the first elastic wave resonator (10A) and the second elastic wave resonator (10B) is a divided resonator in which a single elastic wave resonator is divided in series.

Description

Technical Field

[0001] The present invention relates to an elastic wave device having a plurality of elastic wave resonators. Background Art

[0002] Conventionally, elastic wave devices have been widely used for filters of mobile phones and the like. In recent years, an elastic wave device using a bulk wave of a thickness shear mode as described in Patent Document 1 below has been proposed. In this elastic wave device, a piezoelectric layer is provided on a support body. Paired electrodes are provided on the piezoelectric layer. The paired electrodes are opposed to each other on the piezoelectric layer and are connected to different potentials. By applying an alternating voltage between the above electrodes, a bulk wave of a thickness shear mode is excited.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Specification of U.S. Patent No. 10491192 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] An elastic wave device is, for example, an elastic wave resonator such as an elastic wave resonator. The elastic wave resonator is used for, for example, a ladder filter. In order to obtain good characteristics in a ladder filter, it is necessary to increase the electrostatic capacitance ratio between a plurality of elastic wave resonators. In this case, it is necessary to increase the electrostatic capacitance of a part of the elastic wave resonators in the ladder filter.

[0008] In order to increase the electrostatic capacitance of the elastic wave resonator, for example, it is necessary to make the elastic wave resonator large. Therefore, when this elastic wave resonator is used for a ladder filter, the ladder filter tends to become large. In particular, a ladder filter having an elastic wave resonator using a bulk wave of a thickness shear mode with a small electrostatic capacitance becomes large.

[0009] The inventors of the present invention have found that, when the elastic wave resonator is used for a filter device, an appropriate filter waveform can be obtained without increasing the size by setting the structure of the elastic wave resonator to the following structure. This structure is a structure in which an electrode connected to a reference potential or a potential different from the input potential and the output potential is disposed between an electrode connected to the input potential and an electrode connected to the output potential.

[0010] In addition, the inventors of the present invention have also found that, simply adopting the above structure may not be able to sufficiently improve the power resistance.

[0011] An object of the present invention is to provide an elastic wave device capable of promoting miniaturization of a filter device and improving power resistance.

[0012] Technical solution for solving the problem

[0013] In a broad aspect of the elastic wave device according to the present invention, it includes:

[0014] A first elastic wave resonator; and

[0015] A second elastic wave resonator,

[0016] The first elastic wave resonator and the second elastic wave resonator each have a piezoelectric film, a first comb-shaped electrode connected to an input potential, a second comb-shaped electrode connected to an output potential, and a third electrode connected to a reference potential,

[0017] The piezoelectric film includes a piezoelectric layer, and the piezoelectric layer includes lithium niobate,

[0018] The first comb-shaped electrode is provided on the piezoelectric layer and has a first bus bar and a plurality of first electrode fingers, and one ends of the plurality of first electrode fingers are respectively connected to the first bus bar,

[0019] The second comb-shaped electrode is provided on the piezoelectric layer and has a second bus bar and a plurality of second electrode fingers, and one ends of the plurality of second electrode fingers are respectively connected to the second bus bar, and the plurality of second electrode fingers are interlaced with and inserted into the plurality of first electrode fingers,

[0020] The third electrode has a plurality of third electrode fingers and connection electrodes connecting adjacent third electrode fingers to each other, and the third electrode fingers are respectively arranged on the piezoelectric layer so as to be arranged in the direction in which the first electrode fingers and the second electrode fingers are arranged when viewed from above,

[0021] In each of the first elastic wave resonator and the second elastic wave resonator, when viewed from above, the order in which the first electrode fingers, the second electrode fingers, and the third electrode fingers are arranged is the order in which the first electrode fingers, the third electrode fingers, the second electrode fingers, and the third electrode fingers are taken as one cycle starting from the first electrode fingers,

[0022] The first elastic wave resonator and the second elastic wave resonator are respectively divided resonators obtained by serially dividing one elastic wave resonator.

[0023] In another broad aspect of the elastic wave device according to the present invention, it includes:

[0024] A first elastic wave resonator; and

[0025] A second elastic wave resonator,

[0026] The first elastic wave resonator and the second elastic wave resonator each have a piezoelectric film, a first comb-shaped electrode connected to an input potential, a second comb-shaped electrode connected to an output potential, and a third electrode connected to a reference potential.

[0027] The piezoelectric film includes a piezoelectric layer, and the piezoelectric layer includes lithium niobate.

[0028] The first comb-shaped electrode is disposed on the piezoelectric layer and has a first bus bar and a plurality of first electrode fingers, and one ends of the plurality of first electrode fingers are respectively connected to the first bus bar.

[0029] The second comb-shaped electrode is disposed on the piezoelectric layer and has a second bus bar and a plurality of second electrode fingers, and one ends of the plurality of second electrode fingers are respectively connected to the second bus bar. The plurality of second electrode fingers are interleaved with the plurality of first electrode fingers.

[0030] The third electrode has a plurality of third electrode fingers and connection electrodes connecting adjacent third electrode fingers to each other. The third electrode fingers are respectively disposed on the piezoelectric layer so as to be arranged in the direction in which the first electrode fingers and the second electrode fingers are arranged when viewed from above.

[0031] In each of the first elastic wave resonator and the second elastic wave resonator, when viewed from above, the order in which the first electrode fingers, the second electrode fingers, and the third electrode fingers are arranged is the order in which the first electrode fingers, the third electrode fingers, the second electrode fingers, and the third electrode fingers are taken as one cycle starting from the first electrode fingers.

[0032] The first elastic wave resonator and the second elastic wave resonator are respectively divided resonators obtained by parallel-dividing one elastic wave resonator.

[0033] Advantages of the Invention

[0034] According to the present invention, an elastic wave device capable of promoting miniaturization of a filter device and improving power resistance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic top view of an elastic wave device according to a first embodiment of the present invention.

[0036] Figure 2 is a schematic front cross-sectional view of the first elastic wave resonator in the first embodiment of the present invention.

[0037] Figure 3 is a schematic top view of the first elastic wave resonator in the first embodiment of the present invention.

[0038] Figure 4 is a schematic front sectional view showing the vicinity of the first electrode finger to the third electrode finger in the first embodiment of the present invention.

[0039] Figure 5 is a schematic top view of the second elastic wave resonator in the first embodiment of the present invention.

[0040] Figure 6 is a graph showing the passing characteristics in the first embodiment of the present invention.

[0041] Figure 7 is a graph showing the mapping of the relative bandwidth with respect to the Euler angles (0°, θ, ψ) of LiNbO 3 when d / p approaches 0 infinitely.

[0042] Figure 8 is a schematic top view of the first elastic wave resonator in a modified example of the first embodiment of the present invention.

[0043] Figure 9 is a graph showing the passing characteristics in the first embodiment and the second embodiment of the present invention.

[0044] Figure 10 is a graph showing the passing characteristics in the first embodiment and the third embodiment of the present invention.

[0045] Figure 11 is a graph showing the passing characteristics in the first embodiment and the fourth embodiment of the present invention.

[0046] Figure 12 is a graph showing the passing characteristics in the first embodiment and the fifth embodiment of the present invention.

[0047] Figure 13 is a schematic front sectional view of the first elastic wave resonator in the ninth embodiment of the present invention.

[0048] Figure 14 is a schematic front sectional view of the second elastic wave resonator in the ninth embodiment of the present invention.

[0049] Figure 15 is a graph showing the passing characteristics in the first embodiment and the ninth embodiment of the present invention.

[0050] Figure 16 is a schematic top view of the elastic wave device according to the tenth embodiment of the present invention.

[0051] Figure 17 is a schematic top view of the second elastic wave resonator in the tenth embodiment of the present invention.

[0052] Figure 18 It is a schematic top view of a surface acoustic wave device according to a modified example of the 10th embodiment of the present invention.

[0053] Figure 19 It is a graph showing the pass characteristics in the 1st embodiment and the 10th embodiment of the present invention.

[0054] Figure 20 It is a graph showing the pass characteristics in the 10th embodiment and its modified examples of the present invention.

[0055] Figure 21 It is a schematic top view of a surface acoustic wave device according to the 11th embodiment of the present invention.

[0056] Figure 22 It is along Figure 21 A schematic cross-sectional view taken along line II-II in

[0057] Figure 23 It is a schematic top view of a surface acoustic wave device according to the 12th embodiment of the present invention.

[0058] Figure 24 It is a schematic top view of a surface acoustic wave device according to the 13th embodiment of the present invention.

[0059] Figure 25 It is a schematic front cross-sectional view showing the vicinity of the 1st electrode finger to the 3rd electrode finger of the 1st surface acoustic wave resonator in the 13th embodiment of the present invention.

[0060] Figure 26 (a) of Figure 26 is a schematic perspective view showing the appearance of a surface acoustic wave device using a thickness-shear mode bulk wave,

[0061] Figure 27 is Figure 26 A partial cross-sectional view taken along line A-A in (a) of

[0062] Figure 28 (a) of Figure 28 is a schematic front cross-sectional view for explaining a Lamb wave propagating in a piezoelectric film of a surface acoustic wave device,

[0063] Figure 29 is a graph showing the amplitude direction of a thickness-shear mode bulk wave.

[0064] Figure 30 is a graph showing the resonance characteristics of a surface acoustic wave device using a thickness-shear mode bulk wave.

[0065] Figure 31 It is a diagram showing the relationship between d / p and the relative bandwidth of a resonator when the distance between the centers of adjacent electrodes is set to p and the thickness of the piezoelectric layer is set to d.

[0066] Figure 32 It is a top view of a bulk acoustic wave device using thickness-shear mode body waves.

[0067] Figure 33 It is a diagram showing the resonance characteristics of a bulk acoustic wave device in a reference example where spurious signals appear.

[0068] Figure 34 It is a diagram showing the relationship between the relative bandwidth and the phase rotation amount of the impedance of a spurious signal normalized by 180 degrees, which represents the magnitude of the spurious signal.

[0069] Figure 35 It is a diagram showing the relationship between d / 2p and the metallization ratio MR.

[0070] Figure 36 It is a diagram showing the mapping of the relative bandwidth with respect to the Euler angles (0°, θ, ψ) of LiNbO 3 when d / p is infinitely close to 0.

[0071] Figure 37 It is a front view cross-sectional view of a bulk acoustic wave device having an acoustic multilayer film.

[0072] Figure 38 It is a partial cutaway perspective view for explaining a bulk acoustic wave device using Lamb waves. Detailed Embodiments

[0073] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings to clarify the present invention.

[0074] In addition, it should be noted that each embodiment described in this specification is illustrative, and partial replacement or combination of structures can be made between different embodiments.

[0075] Figure 1 It is a schematic top view of a bulk acoustic wave device according to the first embodiment of the present invention.

[0076] The bulk acoustic wave device 10 is used as part of a filter device. The bulk acoustic wave device 10 has a plurality of bulk acoustic wave resonators. However, the bulk acoustic wave device according to the present invention can also be a filter device. Hereinafter, the structure of the bulk acoustic wave device 10 will be described.

[0077] The elastic wave device 10 includes a first elastic wave resonator 10A and a second elastic wave resonator 10B. The first elastic wave resonator 10A and the second elastic wave resonator 10B are each a surface acoustic wave coupled filter. The first elastic wave resonator 10A has a functional electrode 11. The second elastic wave resonator 10B has a functional electrode 31.

[0078] The first elastic wave resonator 10A and the second elastic wave resonator 10B are electrically connected. Specifically, in the elastic wave device 10, the first elastic wave resonator 10A and the second elastic wave resonator 10B are connected in series with each other.

[0079] The feature of the present embodiment is that the first elastic wave resonator 10A and the second elastic wave resonator 10B are each a divided resonator obtained by serially dividing one elastic wave resonator. In this specification, when two elastic wave resonators are divided resonators, it means that the difference in resonance frequencies between one elastic wave resonator and the other elastic wave resonator connected in series or parallel is 1% or less with respect to any one of the resonance frequencies of the two elastic wave resonators. By the elastic wave device 10 having the above structure, when the elastic wave device 10 is used in a filter device, miniaturization of the filter device can be promoted, and power resistance can be improved. Hereinafter, it will be described in detail together with the details of the present embodiment.

[0080] As Figure 1 shown, the elastic wave device 10 has a piezoelectric substrate 12. The piezoelectric substrate 12 is a substrate having piezoelectricity. The piezoelectric substrate 12 has a piezoelectric layer 14 as a piezoelectric film. The piezoelectric layer 14 is a layer made of a piezoelectric material. On the other hand, in this specification, a piezoelectric film is a film having piezoelectricity, and does not necessarily mean a film made of a piezoelectric material. However, in the present embodiment, the piezoelectric film is a single-layer piezoelectric layer 14 and is a film made of a piezoelectric material. In addition, in the present invention, the piezoelectric film may also be a laminated film including the piezoelectric layer 14.

[0081] In the present embodiment, the piezoelectric substrate 12 is a laminate including the piezoelectric layer 14. The first elastic wave resonator 10A and the second elastic wave resonator 10B share the piezoelectric substrate 12. Moreover, the first elastic wave resonator 10A and the second elastic wave resonator 10B share the piezoelectric layer 14 as a piezoelectric film.

[0082] Figure 2 is a schematic front sectional view of the first elastic wave resonator in the first embodiment. Figure 3 is a schematic top view of the first elastic wave resonator in the first embodiment. In addition, Figure 2 is along Figure 3 in the I-I line schematic sectional view. In Figure 3In the figure, hatching is attached to each electrode. Sometimes, hatching is also attached to the electrodes in the same manner in schematic top views other than Figure 3 . In Figure 3 , wirings connected to the first surface acoustic wave resonator 10A, etc., and the second surface acoustic wave resonator 10B are omitted. Figure 3 In the same way, hatching is also attached to the electrodes in schematic top views other than Figure 3 . In Figure 3 , wirings connected to the first surface acoustic wave resonator 10A, etc., and the second surface acoustic wave resonator 10B are omitted. Figure 3 In Figure 3 , wirings connected to the first surface acoustic wave resonator 10A, etc., and the second surface acoustic wave resonator 10B are omitted.

[0083] Figure 2 The first surface acoustic wave resonator 10A shown has a piezoelectric substrate 12 and functional electrodes 11 as described above. The piezoelectric substrate 12 has a support member 13 and a piezoelectric layer 14 as a piezoelectric film. In the present embodiment, the support member 13 includes a support substrate 16 and an insulating layer 15. The insulating layer 15 is provided on the support substrate 16. The piezoelectric layer 14 is provided on the insulating layer 15. However, the support member 13 may also be composed of only the support substrate 16.

[0084] The piezoelectric layer 14 has a first main surface 14a and a second main surface 14b. The first main surface 14a and the second main surface 14b face each other. When viewed in the direction in which the first main surface 14a and the second main surface 14b of the piezoelectric layer 14 face each other, the piezoelectric layer 14 and the support member 13 overlap. The second main surface 14b of the first main surface 14a and the second main surface 14b is located on the support member 13 side. The functional electrodes 11 are provided on the first main surface 14a of the piezoelectric layer 14.

[0085] As the material of the support substrate 16, for example, semiconductors such as silicon, ceramics such as alumina, etc. can be used. As the material of the insulating layer 15, appropriate dielectrics such as silicon oxide or tantalum oxide can be used. The piezoelectric layer 14 is composed of a lithium niobate layer such as a LiNbO layer, etc. In this specification, when a certain member includes a certain material, it includes the case where a trace amount of impurities that do not significantly deteriorate the electrical characteristics of the surface acoustic wave device are included. 3 In this specification, when a certain member includes a certain material, it includes the case where a trace amount of impurities that do not significantly deteriorate the electrical characteristics of the surface acoustic wave device are included.

[0086] A plurality of recesses are provided in the insulating layer 15. The piezoelectric layer 14 as a piezoelectric film is provided on the insulating layer 15 so as to seal the plurality of recesses. Thus, a plurality of hollow portions are formed. These hollow portions are the cavity portions 10a and the cavity portions 10b shown. In the present embodiment, the support member 13 and the piezoelectric film are arranged such that a part of the support member 13 and a part of the piezoelectric film face each other with the cavity portions 10a and the cavity portions 10b interposed therebetween. However, the recesses in the support member 13 may also be provided so as to cross the insulating layer 15 and the support substrate 16. Or, it may be that the recesses provided only in the support substrate 16 are sealed by the insulating layer 15. The recesses may also be provided in the piezoelectric layer 14, for example. In addition, the cavity portions 10a and the cavity portions 10b may also be through holes provided in the support member 13. Figure 1 A plurality of recesses are provided in the insulating layer 15. The piezoelectric layer 14 as a piezoelectric film is provided on the insulating layer 15 so as to seal the plurality of recesses. Thus, a plurality of hollow portions are formed. These hollow portions are the cavity portions 10a and the cavity portions 10b shown. In the present embodiment, the support member 13 and the piezoelectric film are arranged such that a part of the support member 13 and a part of the piezoelectric film face each other with the cavity portions 10a and the cavity portions 10b interposed therebetween. However, the recesses in the support member 13 may also be provided so as to cross the insulating layer 15 and the support substrate 16. Or, it may be that the recesses provided only in the support substrate 16 are sealed by the insulating layer 15. The recesses may also be provided in the piezoelectric layer 14, for example. In addition, the cavity portions 10a and the cavity portions 10b may also be through holes provided in the support member 13.

[0087] The cavity portions 10a and 10b are the acoustic reflection portions in the present invention. Through the cavity portion 10a as the acoustic reflection portion, the energy of the elastic wave of the first elastic wave resonator 10A can be effectively confined to the piezoelectric layer 14 side. The cavity portion 10a is disposed, in a plan view, at a position in the support member 13 that overlaps at least a part of the functional electrode 11. On the other hand, through the cavity portion 10b as the acoustic reflection portion, the energy of the elastic wave of the second elastic wave resonator 10B can be effectively confined to the piezoelectric layer 14 side. The cavity portion 10b is disposed, in a plan view, at a position in the support member 13 that overlaps at least a part of the functional electrode 31.

[0088] In this specification, the plan view means observing from the direction corresponding to the Figure 2 above in the stacking direction of the support member 13 and the piezoelectric film. Further, in Figure 2 , for example, the piezoelectric layer 14 side in the support substrate 16 side and the piezoelectric layer 14 side is the upper side. Furthermore, in this specification, it is assumed that the plan view is synonymous with the observation from the main surface facing direction. The main surface facing direction is the direction in which the first main surface 14a and the second main surface 14b of the piezoelectric layer 14 face each other. More specifically, the main surface facing direction is, for example, the normal direction of the first main surface 14a.

[0089] As Figure 3 shown, the functional electrode 11 has a pair of comb-shaped electrodes and a third electrode 19. Specifically, the pair of comb-shaped electrodes are a first comb-shaped electrode 17 and a second comb-shaped electrode 18. The first comb-shaped electrode 17 is connected to the input potential. The second comb-shaped electrode 18 is connected to the output potential. In the present embodiment, the third electrode 19 is connected to the reference potential. In the present embodiment, the third electrode 19 is a reference potential electrode. Further, the third electrode 19 does not necessarily have to be connected to the reference potential. The third electrode 19 may be connected to a potential different from that of the first comb-shaped electrode 17 and the second comb-shaped electrode 18. However, it is preferable that the third electrode 19 is connected to the reference potential.

[0090] The first comb-shaped electrode 17 and the second comb-shaped electrode 18 are provided on the first main surface 14a of the piezoelectric layer 14. The first comb-shaped electrode 17 has a first bus bar 22 and a plurality of first electrode fingers 25. One ends of the plurality of first electrode fingers 25 are respectively connected to the first bus bar 22. The second comb-shaped electrode 18 has a second bus bar 23 and a plurality of second electrode fingers 26. One ends of the plurality of second electrode fingers 26 are respectively connected to the second bus bar 23.

[0091] The first bus bar 22 and the second bus bar 23 face each other. The plurality of first electrode fingers 25 and the plurality of second electrode fingers 26 are interlaced with each other. In the direction orthogonal to the direction in which the first electrode fingers 25 and the second electrode fingers 26 extend, the first electrode fingers 25 and the second electrode fingers 26 are alternately arranged.

[0092] The third electrode 19 has a third bus bar 24 as a connection electrode and a plurality of third electrode fingers 27. The plurality of third electrode fingers 27 are provided on the first main surface 14a of the piezoelectric layer 14. The plurality of third electrode fingers 27 are electrically connected to each other through the third bus bar 24.

[0093] In a plan view, the plurality of third electrode fingers 27 are respectively arranged in the direction in which the first electrode fingers 25 and the second electrode fingers 26 are arranged, so as to be arranged with the first electrode fingers 25 and the second electrode fingers 26. Therefore, the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 are arranged in one direction. The plurality of third electrode fingers 27 extend in parallel with the plurality of first electrode fingers 25 and the plurality of second electrode fingers 26.

[0094] Hereinafter, the direction in which the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 extend is defined as the electrode finger extension direction, and the direction orthogonal to the electrode finger extension direction is defined as the electrode finger orthogonal direction. When the direction in which the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 are arranged is defined as the electrode finger arrangement direction, the electrode finger arrangement direction is parallel to the electrode finger orthogonal direction. In this specification, the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 may sometimes be collectively referred to only as electrode fingers. The first bus bar 22 and the second bus bar 23 may sometimes be collectively referred to only as bus bars.

[0095] Figure 4 It is a schematic front sectional view showing the vicinity of the first electrode finger to the third electrode finger in the first embodiment.

[0096] In a plan view, the order in which the plurality of electrode fingers are arranged, starting from the first electrode finger 25, is the order with the first electrode finger 25, the third electrode finger 27, the second electrode finger 26, and the third electrode finger 27 as one cycle. Therefore, the order in which the plurality of electrode fingers are arranged continues like the first electrode finger 25, the third electrode finger 27, the second electrode finger 26, the third electrode finger 27, the first electrode finger 25, the third electrode finger 27, the second electrode finger 26... If the input potential is represented by IN, the output potential is represented by OUT, the reference potential is represented by GND, and the order of the plurality of electrode fingers is represented by the order of the connected potentials, it continues like IN, GND, OUT, GND, IN, GND, OUT...

[0097] In the present embodiment, in the region where the plurality of electrode fingers are provided, the electrode fingers at both end portions in the electrode finger orthogonal direction are both the third electrode fingers 27. In addition, in this region, the electrode fingers at the end portions in the electrode finger orthogonal direction may also be any one of the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27.

[0098] As Figure 3As shown, the third bus bar 24 of the third electrode 19, which serves as a connection electrode, electrically connects the plurality of third electrode fingers 27 to each other. Specifically, the third bus bar 24 is located in the region between the first bus bar 22 and the front ends of the plurality of second electrode fingers 26. The plurality of first electrode fingers 25 are also located in this region. However, the third bus bar 24 and the plurality of first electrode fingers 25 are electrically insulated from each other by the insulating film 29A.

[0099] More specifically, the third bus bar 24 includes a plurality of first connection electrodes 24A and one second connection electrode 24B. Each first connection electrode 24A connects the front ends of two adjacent third electrode fingers 27 to each other. The first connection electrode 24A and the two third electrode fingers 27 form a U-shaped electrode. The second connection electrode 24B connects the plurality of first connection electrodes 24A to each other. An insulating film 29A is provided between the second connection electrode 24B and the plurality of first electrode fingers 25.

[0100] More specifically, the insulating film 29A is provided on the first main surface 14a of the piezoelectric layer 14 so as to cover a part of the plurality of first electrode fingers 25. The insulating film 29A is provided in the region between the first bus bar 22 and the front ends of the plurality of second electrode fingers 26. The insulating film 29A has a strip shape.

[0101] The insulating film 29A does not reach the first connection electrodes 24A of the third electrode 19. Moreover, the second connection electrode 24B is provided across the insulating film 29A and the plurality of first connection electrodes 24A. Specifically, the second connection electrode 24B has a strip portion 24a and a plurality of protruding portions 24b. Each protruding portion 24b extends from the strip portion 24a toward each first connection electrode 24A. Each protruding portion 24b is connected to each first connection electrode 24A. Thus, the plurality of third electrode fingers 27 are electrically connected to each other through the first connection electrodes 24A and the second connection electrode 24B.

[0102] In the present embodiment, the third bus bar 24 is located in the region between the first bus bar 22 and the front ends of the plurality of second electrode fingers 26. Therefore, the front ends of the plurality of second electrode fingers 26 are opposed to the third bus bar 24 with a gap g1 therebetween in the electrode finger extending direction. On the other hand, the front ends of the plurality of first electrode fingers 25 are opposed to the second bus bar 23 with a gap g2 therebetween in the electrode finger extending direction.

[0103] Alternatively, the third bus bar 24 may be located in the region between the second bus bar 23 and the front ends of the plurality of first electrode fingers 25. In this case, the front ends of the plurality of first electrode fingers 25 are opposed to the third bus bar 24 with a gap therebetween. On the other hand, the front ends of the plurality of second electrode fingers 26 are opposed to the first bus bar 22 with a gap therebetween.

[0104] In this way, in the first elastic wave resonator 10A, when the third electrode 19 is a reference potential electrode, it can be configured as follows. As long as the front ends of the plurality of first electrode fingers 25 are respectively opposed to an electrode connected to a potential that is different from the potential of the electrode finger in the electrode finger extending direction and is any one of the input potential, the output potential, and the reference potential with a gap therebetween. Similarly, as long as the front ends of the plurality of second electrode fingers 26 are respectively opposed to an electrode connected to a potential that is different from the potential of the electrode finger in the electrode finger extending direction and is any one of the input potential, the output potential, and the reference potential with a gap therebetween.

[0105] The dimension of these gaps in the electrode finger extending direction is defined as the gap length. In the present embodiment, the gap length of the gap g1 and the gap length of the gap g2 are the same. However, the gap length of the gap g1 and the gap length of the gap g2 may also be different from each other.

[0106] The first elastic wave resonator 10A is an elastic wave resonator configured to be able to utilize a thickness shear mode bulk wave. As Figure 3 shown, the first elastic wave resonator 10A has a plurality of excitation regions C. In the plurality of excitation regions C, a thickness shear mode bulk wave and elastic waves of other modes are excited. In addition, Figure 3 only two of the plurality of excitation regions C are shown.

[0107] A part of the plurality of excitation regions C among all the excitation regions C is a region where the adjacent first electrode finger 25 and the third electrode finger 27 overlap when viewed from the direction orthogonal to the electrode finger, and is a region between the centers of the adjacent first electrode finger 25 and the third electrode finger 27. The remaining plurality of excitation regions C are regions where the adjacent second electrode finger 26 and the third electrode finger 27 overlap when viewed from the direction orthogonal to the electrode finger, and are regions between the centers of the adjacent second electrode finger 26 and the third electrode finger 27. These excitation regions C are arranged in the direction orthogonal to the electrode finger.

[0108] In the functional electrode 11, the structure other than the third electrode 19 is the same as the structure of an IDT (Interdigital Transducer) electrode. When viewed from the direction orthogonal to the electrode finger, the region where the adjacent first electrode finger 25 and the second electrode finger 26 overlap is the crossover region E. However, it can also be said that the crossover region E is a region where the adjacent first electrode finger 25 and the third electrode finger 27 or the adjacent second electrode finger 26 and the third electrode finger 27 overlap when viewed from the direction orthogonal to the electrode finger. The crossover region E includes a plurality of excitation regions C. In addition, the crossover region E and the excitation regions C of the first elastic wave resonator 10A are regions of the piezoelectric layer 14 defined based on the structure of the functional electrode 11.

[0109] Figure 5 is a schematic top view of the second elastic wave resonator in the first embodiment. In addition, in Figure 5 , wirings connected to the second elastic wave resonator 10B and the like, and the first elastic wave resonator 10A are omitted.

[0110] The second elastic wave resonator 10B is configured to be able to utilize a bulk wave in the thickness shear mode. The second elastic wave resonator 10B is an acoustic coupling type filter. The second elastic wave resonator 10B shares the piezoelectric substrate 12 with the first elastic wave resonator 10A. The second elastic wave resonator 10B has the above-mentioned functional electrode 31. More specifically, the functional electrode 31 is provided on the first main surface 14a of the piezoelectric layer 14 in the piezoelectric substrate 12. The structure of the functional electrode 31 of the second elastic wave resonator 10B is basically the same as the structure of the functional electrode 11 of the first elastic wave resonator 10A.

[0111] More specifically, the second elastic wave resonator 10B independently includes a first comb-shaped electrode, a second comb-shaped electrode, and a third electrode with the first elastic wave resonator 10A. In addition, hereinafter, the first comb-shaped electrode of the second elastic wave resonator 10B is designated as the fourth comb-shaped electrode. The second comb-shaped electrode of the second elastic wave resonator 10B is designated as the fifth comb-shaped electrode. The third electrode of the second elastic wave resonator 10B is designated as the sixth electrode.

[0112] The fourth comb-shaped electrode is connected to the input potential. The fifth comb-shaped electrode is connected to the output potential. In addition, in the present embodiment, the first elastic wave resonator 10A and the second elastic wave resonator 10B are connected in series with each other. Specifically, the fourth comb-shaped electrode is connected to the output potential of the first elastic wave resonator 10A.

[0113] In the present embodiment, the sixth electrode of the second elastic wave resonator 10B is connected to the reference potential. In the present embodiment, the sixth electrode is a reference potential electrode. In addition, the sixth electrode does not necessarily have to be connected to the reference potential. The sixth electrode may be connected to a potential different from the fourth comb-shaped electrode and the fifth comb-shaped electrode. However, it is preferable that the sixth electrode is connected to the reference potential.

[0114] The fourth comb-shaped electrode and the fifth comb-shaped electrode are provided on the first main surface 14a of the piezoelectric layer 14. The fourth comb-shaped electrode has a fourth bus bar 32 as the first bus bar and a plurality of fourth electrode fingers 35 as a plurality of first electrode fingers. One ends of the plurality of fourth electrode fingers 35 are respectively connected to the fourth bus bar 32.

[0115] In addition, in the present embodiment, the fourth bus bar 32 in the second elastic wave resonator 10B is shared by the first elastic wave resonator 10A. Specifically, the fourth bus bar 32 is Figure 1The second bus bar 23 in the first surface acoustic wave resonator 10A shown. However, the second bus bar 23 of the first surface acoustic wave resonator 10A and the fourth bus bar 32 of the second surface acoustic wave resonator 10B may also be provided independently.

[0116] Return to Figure 5 , the fifth comb-shaped electrode has a fifth bus bar 33 as the second bus bar and a plurality of fifth electrode fingers 36 as a plurality of second electrode fingers. One ends of the plurality of fifth electrode fingers 36 are respectively connected to the fifth bus bar 33.

[0117] The fourth bus bar 32 and the fifth bus bar 33 face each other. The plurality of fourth electrode fingers 35 and the plurality of fifth electrode fingers 36 are interdigitated with each other. In a direction orthogonal to the direction in which the fourth electrode fingers 35 and the fifth electrode fingers 36 extend, the fourth electrode fingers 35 and the fifth electrode fingers 36 are alternately arranged.

[0118] The sixth electrode has a sixth bus bar 34 as a connection electrode and a plurality of sixth electrode fingers 37 as a plurality of third electrode fingers. The plurality of sixth electrode fingers 37 are provided on the first main surface 14a of the piezoelectric layer 14. The plurality of sixth electrode fingers 37 are electrically connected to each other through the sixth bus bar 34. The sixth bus bar 34 is formed in the same manner as the third bus bar 24 of the first surface acoustic wave resonator 10A. Thus, the sixth bus bar has a first connection electrode and a second connection electrode.

[0119] In a plan view, the plurality of sixth electrode fingers 37 are respectively arranged to be arranged with the fourth electrode fingers 35 and the fifth electrode fingers 36 in the direction in which the fourth electrode fingers 35 and the fifth electrode fingers 36 are arranged. Thus, the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 are arranged in one direction. The plurality of sixth electrode fingers 37 extend in parallel with the plurality of fourth electrode fingers 35 and the plurality of fifth electrode fingers 36.

[0120] In the second surface acoustic wave resonator 10B, the direction in which the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 extend is the electrode finger extension direction, and the direction orthogonal to the electrode finger extension direction is the electrode finger orthogonal direction. Hereinafter, the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 may sometimes be collectively referred to only as a plurality of electrode fingers.

[0121] In a plan view, the order in which the plurality of electrode fingers are arranged in the second surface acoustic wave resonator 10B is the order in which the fourth electrode fingers 35, the sixth electrode fingers 37, the fifth electrode fingers 36, and the sixth electrode fingers 37 are taken as one cycle when starting from the fourth electrode fingers 35. That is, in the second surface acoustic wave resonator 10B, in the same manner as the first surface acoustic wave resonator 10A, the order in which the plurality of electrode fingers are arranged is the order in which the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger are taken as one cycle when starting from the first electrode finger.

[0122] The sixth bus bar 34 is located in the region between the fourth bus bar 32 and the front ends of the plurality of fifth electrode fingers 36. In addition, the sixth bus bar 34 and the plurality of fourth electrode fingers 35 are electrically insulated by the insulating film 29B.

[0123] The front ends of the plurality of fifth electrode fingers 36 face the sixth bus bar 34 with a gap g4 therebetween in the electrode finger extending direction. On the other hand, the front ends of the plurality of fourth electrode fingers 35 face the fifth bus bar 33 with a gap g5 therebetween in the electrode finger extending direction.

[0124] In addition, in the second surface acoustic wave resonator 10B, when the sixth electrode is a reference potential electrode, it may be configured as follows in the same manner as the first surface acoustic wave resonator 10A. The front ends of the plurality of fourth electrode fingers 35 only need to face an electrode connected to a potential that is different from the potential of the electrode finger and is any one of the input potential, the output potential, and the reference potential with a gap therebetween in the electrode finger extending direction. Similarly, the front ends of the plurality of fifth electrode fingers 36 only need to face an electrode connected to a potential that is different from the potential of the electrode finger and is any one of the input potential, the output potential, and the reference potential with a gap therebetween in the electrode finger extending direction.

[0125] The dimension of these gaps in the electrode finger extending direction is the gap length of the second surface acoustic wave resonator 10B. In the present embodiment, the gap length of the gap g4 and the gap length of the gap g5 are the same. However, the gap length of the gap g4 and the gap length of the gap g5 may also be different from each other.

[0126] The second surface acoustic wave resonator 10B has a plurality of excitation regions and crossover regions in the same manner as the first surface acoustic wave resonator 10A. Specifically, a part of the plurality of excitation regions in all the excitation regions is a region where the adjacent fourth electrode fingers 35 and the sixth electrode fingers 37 overlap when viewed from the direction orthogonal to the electrode fingers, and is a region between the centers of the adjacent fourth electrode fingers 35 and the sixth electrode fingers 37. The remaining plurality of excitation regions are regions where the adjacent fifth electrode fingers 36 and the sixth electrode fingers 37 overlap when viewed from the direction orthogonal to the electrode fingers, and are regions between the centers of the adjacent fifth electrode fingers 36 and the sixth electrode fingers 37. These excitation regions are arranged in the direction orthogonal to the electrode fingers.

[0127] When viewed from the direction orthogonal to the electrode fingers, the overlapping region of adjacent fourth electrode fingers 35 and fifth electrode fingers 36 is the crossover region. However, it can also be said that the crossover region is the overlapping region of adjacent fourth electrode fingers 35 and sixth electrode fingers 37 or adjacent fifth electrode fingers 36 and sixth electrode fingers 37 when viewed from the direction orthogonal to the electrode fingers. The crossover region and the excitation region of the second elastic wave resonator 10B are regions of the piezoelectric layer 14 defined based on the structure of the functional electrode 31.

[0128] In the present embodiment, when the elastic wave device 10 is used in a filter device, miniaturization of the filter device can be promoted, and the power resistance can be improved. Hereinafter, a detailed description thereof will be given.

[0129] In addition, hereinafter, an elastic wave resonator that forms the basis of a plurality of divided resonators may sometimes be referred to as a basic elastic wave resonator. The first elastic wave resonator 10A and the second elastic wave resonator 10B are configured by serially dividing the basic elastic wave resonator.

[0130] In the elastic wave device 10, the first elastic wave resonator 10A and the second elastic wave resonator 10B are formed, and the basic elastic wave resonator is not formed. However, for convenience, it is assumed that the basic elastic wave resonator is an acoustic coupling type filter similar to the first elastic wave resonator 10A and the second elastic wave resonator 10B. Moreover, it is assumed that the basic elastic wave resonator includes a first comb-shaped electrode, a second comb-shaped electrode, and a third electrode in the same manner as the first elastic wave resonator 10A and the second elastic wave resonator 10B. Hereinafter, an example of the design parameters of the basic elastic wave resonator of the first elastic wave resonator 10A and the second elastic wave resonator 10B is shown.

[0131] Piezoelectric layer: The material is LiNbO 3 , the Euler angles (φ, ψ, θ) are (0°, 0°, 90°), and the thickness is 400 nm

[0132] First electrode finger to third electrode finger: The layer structure from the piezoelectric layer side is Ti layer / AlCu layer / Ti layer, and the thickness from the piezoelectric layer side is 10 nm / 390 nm / 4 nm

[0133] The order of the first electrode finger to the third electrode finger represented by the order of the connected potentials: Repeats the order of IN, GND, OUT, GND.

[0134] The center-to-center distance between adjacent electrode fingers: 1.4 μm

[0135] Duty ratio: 0.3

[0136] By Figure 6Shows the transmission characteristics of the elastic wave device 10 in the case where the first elastic wave resonator 10A and the second elastic wave resonator 10B are divided resonators obtained by serially dividing the elastic wave resonator with the above-described design parameters.

[0137] Figure 6 It is a diagram showing the transmission characteristics in the first embodiment. In addition, in Figure 6 the S12 parameter is shown.

[0138] First, as Figure 6 shown, it can be seen that in the elastic wave device 10 of the present embodiment, filter characteristics are obtained. The first elastic wave resonator 10A in the elastic wave device 10 is an acoustic coupling type filter. More specifically, as Figure 3 shown, the first elastic wave resonator 10A has an excitation region C between the centers of adjacent first electrode fingers 25 and third electrode fingers 27 and an excitation region C between the centers of adjacent second electrode fingers 26 and third electrode fingers 27. In these excitation regions C, elastic waves of a plurality of modes that excite bulk waves including a thickness shear mode are excited. By coupling these modes, a filter waveform can be appropriately obtained.

[0139] In the second elastic wave resonator 10B as well, similar to the first elastic wave resonator 10A, a filter waveform can be obtained. Therefore, in the case where the elastic wave device 10 is used for a filter device, even if the number of elastic wave resonators constituting the filter device is small, a filter waveform can be appropriately obtained. Therefore, miniaturization of the filter device can be promoted.

[0140] In addition to this, in the present embodiment, the first elastic wave resonator 10A and the second elastic wave resonator 10B are each a divided resonator obtained by serially dividing one elastic wave resonator. By serially dividing one elastic wave resonator into a plurality of divided resonators, the total area of the elastic wave resonators becomes larger. As a result, the power per unit area applied to the elastic wave resonators becomes smaller. Thereby, even when a large power is applied, the elastic wave resonators are less likely to be damaged. In this way, the power resistance can be improved. Furthermore, IMD (Intermodulation Distortion) can also be suppressed.

[0141] Hereinafter, the structure of the present embodiment will be described in more detail.

[0142] As Figure 1As shown, a first signal potential wiring 28A, a second signal potential wiring 28B, and a reference potential wiring 28C are provided on a first main surface 14a of a piezoelectric layer 14. The first signal potential wiring 28A is connected to an input potential. The second signal potential wiring 28B is connected to an output potential. The reference potential wiring 28C is connected to a reference potential.

[0143] A first bus bar 22 of a first surface acoustic wave resonator 10A is connected to the first signal potential wiring 28A. A fifth bus bar 33 of a second surface acoustic wave resonator 10B is connected to the second signal potential wiring 28B.

[0144] A third bus bar 24 as a connection electrode of the first surface acoustic wave resonator 10A and a sixth bus bar 34 as a connection electrode of the second surface acoustic wave resonator 10B are connected to the reference potential wiring 28C. The third bus bar 24 and the sixth bus bar 34 are connected to the reference potential via the reference potential wiring 28C. In the present embodiment, the third bus bar 24 and the sixth bus bar 34 are connected to the same reference potential wiring 28C. Additionally, the third bus bar 24 and the sixth bus bar 34 may be connected to different independently provided reference potential wirings 28C.

[0145] A plurality of first electrode fingers 25, a plurality of second electrode fingers 26, and a plurality of third electrode fingers 27 in the first surface acoustic wave resonator 10A overlap a cavity portion 10a as an acoustic reflector in a top view. A plurality of fourth electrode fingers 35, a plurality of fifth electrode fingers 36, and a plurality of sixth electrode fingers 37 in the second surface acoustic wave resonator 10B overlap a cavity portion 10b as an acoustic reflector in a top view.

[0146] Preferably, as in the present embodiment, in a top view, a plurality of excitation regions C of the first surface acoustic wave resonator 10A overlap the cavity portion 10a as an acoustic reflector. Thereby, the energy of the surface acoustic wave in the first surface acoustic wave resonator 10A can be more reliably and effectively confined to the piezoelectric layer 14 side. Preferably, in a top view, a plurality of excitation regions of the second surface acoustic wave resonator 10B overlap the cavity portion 10b as an acoustic reflector. Thereby, the energy of the surface acoustic wave in the second surface acoustic wave resonator 10B can be more reliably and effectively confined to the piezoelectric layer 14 side.

[0147] In addition, the acoustic reflector may be an acoustic reflection film such as an acoustic multilayer film described later. For example, an acoustic reflection film may be provided on the surface of a support member.

[0148] Figure 3The first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 of the first surface acoustic wave resonator 10A shown are formed of a stacked metal film. Specifically, in the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27, a Ti layer, an AlCu layer, and a Ti layer are stacked in this order from the piezoelectric layer 14 side. In addition, the materials of the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 are not limited to the above materials. Alternatively, the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 may be formed of a single-layer metal film.

[0149] For the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 of the second surface acoustic wave resonator 10B, the same materials as those of the respective electrode fingers of the first surface acoustic wave resonator 10A can be used.

[0150] Hereinafter, the distance between the centers of the adjacent first electrode fingers 25 and the third electrode fingers 27 and the distance between the centers of the adjacent second electrode fingers 26 and the third electrode fingers 27 in the first surface acoustic wave resonator 10A are defined as p1. The distance between the centers of the adjacent first electrode fingers and the third electrode fingers and the distance between the centers of the adjacent second electrode fingers and the third electrode fingers in the second surface acoustic wave resonator 10B are defined as p2. That is, the distance between the centers of the adjacent fourth electrode fingers 35 and the sixth electrode fingers 37 and the distance between the centers of the adjacent fifth electrode fingers 36 and the sixth electrode fingers 37 are p2.

[0151] In the present embodiment, in the first surface acoustic wave resonator 10A, the distance p1 between the centers of the adjacent first electrode fingers 25 and the third electrode fingers 27 is the same as the distance p1 between the centers of the adjacent second electrode fingers 26 and the third electrode fingers 27. However, the distance p1 between the centers of the adjacent first electrode fingers 25 and the third electrode fingers 27 and the distance p1 between the centers of the adjacent second electrode fingers 26 and the third electrode fingers 27 may not be fixed. In this case, the longest distance among the distance p1 between the centers of the adjacent first electrode fingers 25 and the third electrode fingers 27 and the distance p1 between the centers of the adjacent second electrode fingers 26 and the third electrode fingers 27 is defined as p. In addition, when the distance p1 between the centers of the adjacent electrode fingers is fixed as in the present embodiment, the distance p1 between any adjacent electrode fingers in the first surface acoustic wave resonator 10A is the distance p.

[0152] Similarly, in the present embodiment, in the second surface acoustic wave resonator 10B, the center-to-center distance p2 between adjacent fourth electrode fingers 35 and sixth electrode fingers 37 is the same as the center-to-center distance p2 between adjacent fifth electrode fingers 36 and sixth electrode fingers 37. However, the center-to-center distance p2 between adjacent fourth electrode fingers 35 and sixth electrode fingers 37 and the center-to-center distance p2 between adjacent fifth electrode fingers 36 and sixth electrode fingers 37 may not be fixed. In this case, the longest distance among the center-to-center distance p2 between adjacent fourth electrode fingers 35 and sixth electrode fingers 37 and the center-to-center distance p2 between adjacent fifth electrode fingers 36 and sixth electrode fingers 37 is defined as p. Further, in the case where the center-to-center distance p2 between adjacent electrode fingers is fixed as in the present embodiment, the center-to-center distance p2 between any adjacent electrode fingers in the second surface acoustic wave resonator 10B is the distance p.

[0153] In each of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B, when the thickness of the piezoelectric film is d, it is preferable that d / p is 0.5 or less, and more preferably d / p is 0.24 or less. Thereby, in each of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B, a thickness-shear mode bulk wave can be appropriately excited. Further, in the present embodiment, the thickness d is the thickness of the piezoelectric layer 14.

[0154] However, the first surface acoustic wave resonator of the present invention does not necessarily have to be configured to utilize a thickness-shear mode bulk wave. For example, the first surface acoustic wave resonator of the present invention may be configured to be able to excite a plate wave. In this case, the excitation region is Figure 3 the cross region E shown. Similarly, the second surface acoustic wave resonator may be configured to be able to excite a plate wave.

[0155] In the present embodiment, the piezoelectric layer 14 contains lithium niobate. The relative bandwidth of the first surface acoustic wave resonator 10A depends on the Euler angles (φ, θ, ψ) of the lithium niobate used for the piezoelectric layer 14. The same applies to the second surface acoustic wave resonator 10B. Further, the so-called relative bandwidth can be represented by (|fa - fr| / fr) × 100 [%] when the resonance frequency is fr and the anti-resonance frequency is fa.

[0156] The relationship between the relative bandwidth of the first surface acoustic wave resonator 10A and the Euler angles (φ, θ, ψ) of the piezoelectric layer 14 in the case where d / p approaches 0 infinitely was derived. Further, φ in the Euler angles is set to 0°.

[0157] Figure 7 is a diagram showing a map of the relative bandwidth with respect to the Euler angles (0°, θ, ψ) of LiNbO 3 in the case where d / p approaches 0 infinitely.

[0158] Figure 7 The region R shown by the attached hatching is the region where a relative bandwidth of at least 2% or more can be obtained. If the range of the region R is approximated, it becomes the range expressed by the following formulas (1), (2), and (3). In addition, when φ in the Euler angles (φ, θ, ψ) is within the range of 0° ± 10°, the relationship between θ, ψ, and the relative bandwidth is the same as Figure 7 the relationship shown.

[0159] (Within the range of 0° ± 10°, 0° to 25°, any ψ) … Formula (1)

[0160] (Within the range of 0° ± 10°, 25° to 100°, 0° to 75° [(1 - (θ - 50) 2 / 2500)] 1 / 2 or 180° - 75° [(1 - (θ - 50) 2 / 2500)] 1 / 2 ~180°) … Formula (2)

[0161] (Within the range of 0° ± 10°, 180° - 40° [(1 - (ψ - 90) 2 / 8100)] 1 / 2 ~180°, any ψ)

[0162] … Formula (3)

[0163] Preferably, it is the range of the Euler angles of the above formulas (1), (2), or (3). Thereby, the relative bandwidth can be made sufficiently wide. Thereby, the elastic wave device 10 including the first elastic wave resonator 10A can be appropriately used for a filter device.

[0164] Similarly, in the second elastic wave resonator 10B, the Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric layer 14 are also preferably within the range of the above formulas (1), (2), or (3). Thereby, the elastic wave device 10 including the second elastic wave resonator 10B can be appropriately used for a filter device.

[0165] In addition, as Figure 3 shown, in the first elastic wave resonator 10A of the first embodiment, the third electrode 19 has the third bus bar 24 as a connection electrode and a plurality of third electrode fingers 27. The third electrode 19 is a comb-shaped electrode. However, the third electrode 19 may not be a comb-shaped electrode. For example, in Figure 8In the modification of the first embodiment shown, the third electrode 19A of the first elastic wave resonator 80A has a meandering shape. In this modification, the insulating film 29A is not provided on the piezoelectric layer 14. Further, the connection electrode 24C only includes a portion corresponding to the plurality of first connection electrodes 24A in the first embodiment. The connection electrode 24C of this modification is not the third bus bar.

[0166] More specifically, the third electrode 19A has a plurality of connection electrodes 24C on the side of the first bus bar 22 and a plurality of connection electrodes 24C on the side of the second bus bar 23. The front end portions of two adjacent third electrode fingers 27 on the side of the first bus bar 22 or the front end portions of the second bus bar 23 are connected to each other by the connection electrode 24C. For example, the third electrode fingers 27 other than the two ends in the orthogonal direction of the plurality of third electrode fingers 27 are each connected to one connection electrode 24C at both the front end portion on the side of the first bus bar 22 and the front end portion on the side of the second bus bar 23. The third electrode finger 27 is connected to the adjacent third electrode fingers 27 through the respective connection electrodes 24C. By repeating this structure, the shape of the third electrode 19A is set to a meandering shape.

[0167] In this modification, the front ends of the plurality of second electrode fingers 26 are opposed to the plurality of connection electrodes 24C with a gap g1 in the electrode finger extending direction. That is, the front ends of the plurality of second electrode fingers 26 are opposed to the electrodes connected to the following potentials with a gap g1 in the electrode finger extending direction, where the potentials are different from those of the electrode fingers and are any one of the input potential, the output potential, and the reference potential. Specifically, the second electrode finger 26 is connected to the output potential, and the connection electrode 24C is connected to the reference potential. The dimension of the gap g1 between the front end of the second electrode finger 26 and the connection electrode 24C in the electrode finger extending direction is the gap length.

[0168] Similarly, the front ends of the plurality of first electrode fingers 25 are opposed to the plurality of connection electrodes 24C with a gap g2 in the electrode finger extending direction. That is, the front ends of the plurality of first electrode fingers 25 are opposed to the electrodes connected to the following potentials with a gap g2 in the electrode finger extending direction, where the potentials are different from those of the electrode fingers and are any one of the input potential, the output potential, and the reference potential. Specifically, the first electrode finger 25 is connected to the input potential, and the connection electrode 24C is connected to the reference potential. The dimension of the gap g2 between the front end of the first electrode finger 25 and the connection electrode 24C in the electrode finger extending direction is the gap length.

[0169] In this modification, the gap length of the gap g1 and the gap length of the gap g2 are the same. However, the gap length of the gap g1 and the gap length of the gap g2 may also be different from each other.

[0170] Although not shown, in the elastic wave device of this modification example, the second elastic wave resonator is also configured in the same manner as the first elastic wave resonator 80A. That is, the shape of the sixth electrode, which is the third electrode in the second elastic wave resonator, is set to a meandering shape. The second elastic wave resonator and the first elastic wave resonator 80A are each a divided resonator obtained by serially dividing one elastic wave resonator. Thus, as in the first embodiment, when the elastic wave device is used in a filter device, miniaturization of the filter device can be promoted, and power resistance can be improved.

[0171] Return to Figure 1 , in the first embodiment, the cavity portion 10a and the cavity portion 10b are provided independently. In addition, the cavity portion 10a and the cavity portion 10b may be provided integrally. The first elastic wave resonator 10A and the second elastic wave resonator 10B may also share the same cavity portion. The structure in which the first elastic wave resonator 10A and the second elastic wave resonator 10B share the same cavity portion can also be adopted in embodiments of the present invention other than the first embodiment.

[0172] Hereinafter, the structures of the second to eighth embodiments will be described. The basic structures of the second to eighth embodiments are the same as those of the first embodiment. Therefore, in the descriptions of the second to eighth embodiments, the drawings and reference numerals used in the description of the first embodiment are cited.

[0173] In addition, in the second to eighth embodiments, the first elastic wave resonator 10A and the second elastic wave resonator 10B are each a divided resonator obtained by serially dividing one elastic wave resonator and are acoustic coupling type filters. Thus, as in the first embodiment, when the elastic wave device is used in a filter device, miniaturization of the filter device can be promoted, and power resistance can be improved.

[0174] In the first embodiment, the total number of the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 of the first elastic wave resonator 10A is the same as the total number of the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 of the second elastic wave resonator 10B. On the other hand, in the second embodiment, the total number of the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 of the first elastic wave resonator 10A is different from the total number of the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 of the second elastic wave resonator 10B. Except for the above aspects, the elastic wave device of the second embodiment is configured in the same manner as the elastic wave device 10 of the first embodiment.

[0175] In the first embodiment and the second embodiment, the filter characteristics were compared. The design parameters of the basic surface acoustic wave resonators of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the second embodiment are as follows.

[0176] Piezoelectric layer: The material is LiNbO 3 , the Euler angles (φ, ψ, θ) are (0°, 0°, 90°), and the thickness is 400 nm

[0177] First electrode finger to third electrode finger: The layer structure is a Ti layer / AlCu layer / Ti layer from the piezoelectric layer side, and the thickness is 10 nm / 390 nm / 4 nm from the piezoelectric layer side

[0178] The order of the first electrode finger to the third electrode finger represented by the order of the connected potentials: The order of IN, GND, OUT, GND is repeated.

[0179] The center-to-center distance between adjacent electrode fingers: 1.4 μm

[0180] Duty ratio: 0.3

[0181] The number of electrode fingers of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the second embodiment is as follows.

[0182] The total number of the first electrode finger to the third electrode finger: 22

[0183] The total number of the fourth electrode finger to the sixth electrode finger: 66

[0184] On the other hand, the design parameters of the basic surface acoustic wave resonators of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the first embodiment are set to be the same as those in the second embodiment. The number of electrode fingers of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the first embodiment is as follows.

[0185] The total number of the first electrode finger to the third electrode finger: 44

[0186] The total number of the fourth electrode finger to the sixth electrode finger: 44

[0187] Figure 9 It is a diagram showing the through characteristics in the first embodiment and the second embodiment. In addition, in Figure 9 , the S12 through characteristic is shown. In the following Figures 10 to 12 , Figure 15 , Figure 19 and Figure 20 it is the same.

[0188] As Figure 9As shown, in the surface acoustic wave device of the second embodiment, filter characteristics can be obtained in the same manner as in the first embodiment. In addition, near the frequency indicated by the arrow F in Figure 9 compared with the first embodiment, the ripples caused by spurious waves in the second embodiment are smaller. In this way, in the second embodiment, the ripples in the frequency characteristics can be suppressed. This is for the following reasons.

[0189] In the second embodiment, in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B, the number of electrode fingers is different from each other. As a result, in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B, the frequencies at which spurious waves are generated are different from each other. As a result, as the surface acoustic wave device as a whole, the ripples caused by spurious waves are smaller.

[0190] Hereinafter, the structure of the third embodiment will be described. In the above-described first embodiment, the center-to-center distance p1 between adjacent electrode fingers in the first surface acoustic wave resonator 10A is the same as the center-to-center distance p2 between adjacent electrode fingers in the second surface acoustic wave resonator 10B. On the other hand, in the third embodiment, the center-to-center distance p1 between adjacent electrode fingers in the first surface acoustic wave resonator 10A and the center-to-center distance p2 between adjacent electrode fingers in the second surface acoustic wave resonator 10B are different from each other. Except for the above aspect, the surface acoustic wave device of the third embodiment is configured in the same manner as the surface acoustic wave device 10 of the first embodiment.

[0191] In addition, in this specification, the center-to-center distance p1 and the center-to-center distance p2 being different from each other means that the absolute value of the difference between the center-to-center distance p1 and the center-to-center distance p2 is 1% or more with respect to either the center-to-center distance p1 or the center-to-center distance p2. The center-to-center distances p1 between each other in one first surface acoustic wave resonator being different from each other means that the absolute value of the difference between the center-to-center distances p1 is 1% or more with respect to any center-to-center distance p1. The same applies to the center-to-center distances p2 between each other in one second surface acoustic wave resonator. In the third embodiment, the center-to-center distance p1 is fixed and the center-to-center distance p2 is fixed.

[0192] In the first embodiment and the third embodiment, the filter characteristics are compared. The design parameters of the basic surface acoustic wave resonators of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the third embodiment are as follows.

[0193] Piezoelectric layer: The material is LiNbO 3 , the Euler angles (φ, ψ, θ) are (0°, 0°, 90°), and the thickness is 400 nm

[0194] 1st electrode finger to 3rd electrode finger: The layer structure is a Ti layer / AlCu layer / Ti layer starting from the piezoelectric layer side, and the thickness is 10 nm / 390 nm / 4 nm starting from the piezoelectric layer side.

[0195] The order of the 1st electrode finger to the 3rd electrode finger represented by the order of the connected potentials: Repeat the order of IN, GND, OUT, GND.

[0196] Duty ratio: 0.3

[0197] The center-to-center distance p1 and the center-to-center distance p2 in the 3rd embodiment are as follows.

[0198] The center-to-center distance p1 between adjacent electrode fingers of the 1st elastic wave resonator: 1.34 μm

[0199] The center-to-center distance p2 between adjacent electrode fingers of the 2nd elastic wave resonator: 1.36 μm

[0200] On the other hand, the design parameters of the basic elastic wave resonators of the 1st elastic wave resonator 10A and the 2nd elastic wave resonator 10B in the 1st embodiment are set to be the same as the design parameters in the 3rd embodiment. The center-to-center distance p1 and the center-to-center distance p2 in the 1st embodiment are as follows.

[0201] The center-to-center distance p1 between adjacent electrode fingers of the 1st elastic wave resonator: 1.34 μm

[0202] The center-to-center distance p2 between adjacent electrode fingers of the 2nd elastic wave resonator: 1.34 μm

[0203] Figure 10 It is a diagram showing the pass characteristics in the 1st embodiment and the 3rd embodiment.

[0204] As Figure 10 shown, in the elastic wave device of the 3rd embodiment, similarly to the 1st embodiment, filter characteristics can be obtained. In addition, near the frequency indicated by the arrow F in Figure 10 , compared with the 1st embodiment, the ripple caused by the unwanted wave in the 3rd embodiment becomes smaller. In this way, in the 3rd embodiment, the ripple in the frequency characteristics can be suppressed.

[0205] In the 3rd embodiment, p1 ≠ p2. Thus, in the 1st elastic wave resonator 10A and the 2nd elastic wave resonator 10B, the frequencies at which unwanted waves are generated are different from each other. Thus, in the 3rd embodiment, the ripple in the frequency characteristics of the elastic wave device can be suppressed.

[0206] In addition, in the first elastic wave resonator 10A, the center-to-center distance p1 may not be fixed. In this case, it is only necessary that the distance p in the first elastic wave resonator 10A and the center-to-center distance p2 in the second elastic wave resonator 10B are different from each other. As described above, the distance p in the first elastic wave resonator 10A is the longest distance among the center-to-center distances p1 between the adjacent first electrode fingers 25 and the third electrode finger 27 and the center-to-center distances p1 between the adjacent second electrode fingers 26 and the third electrode finger 27. When the center-to-center distance p1 is fixed, any center-to-center distance p1 is the distance p.

[0207] Alternatively, in the second elastic wave resonator 10B, the center-to-center distance p2 may not be fixed. In this case, it is only necessary that the distance p in the second elastic wave resonator 10B and the center-to-center distance p1 in the first elastic wave resonator 10A are different from each other. On the other hand, when both the center-to-center distance p1 and the center-to-center distance p2 are not fixed, it is only necessary that the distance p in the first elastic wave resonator 10A and the distance p in the second elastic wave resonator 10B are different from each other.

[0208] Hereinafter, the structure of the fourth embodiment will be described. In the above-described first embodiment, the duty ratios in the first elastic wave resonator 10A and the second elastic wave resonator 10B are the same. On the other hand, in the fourth embodiment, the duty ratios in the first elastic wave resonator 10A and the second elastic wave resonator 10B are different from each other. In this specification, the so-called duty ratios being different from each other means that the absolute value of the difference between the duty ratios is 0.1 or more. Except for the above aspects, the elastic wave device of the fourth embodiment is configured in the same manner as the elastic wave device 10 of the first embodiment.

[0209] In the first embodiment and the fourth embodiment, the filter characteristics are compared. The design parameters of the fundamental elastic wave resonators of the first elastic wave resonator 10A and the second elastic wave resonator 10B in the fourth embodiment are as follows.

[0210] Piezoelectric layer: The material is LiNbO 3 , the Euler angles (φ, ψ, θ) are (0°, 0°, 90°), and the thickness is 400 nm

[0211] First electrode finger to third electrode finger: The layer structure is a Ti layer / AlCu layer / Ti layer from the piezoelectric layer side, and the thicknesses are 10 nm / 390 nm / 4 nm from the piezoelectric layer side.

[0212] The order of the first electrode finger to the third electrode finger represented by the potential to which they are connected: Repeats the order of IN, GND, OUT, GND.

[0213] Distance between the centers of adjacent electrode fingers: 1.4 μm

[0214] The duty ratios in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B of the fourth embodiment are as follows.

[0215] Duty ratio in the first surface acoustic wave resonator: 0.3

[0216] Duty ratio in the second surface acoustic wave resonator: 0.31

[0217] On the other hand, the design parameters of the basic surface acoustic wave resonators of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the first embodiment are set to be the same as those in the fourth embodiment. The duty ratios in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B of the first embodiment are as follows.

[0218] Duty ratio in the first surface acoustic wave resonator: 0.3

[0219] Duty ratio in the second surface acoustic wave resonator: 0.3

[0220] Figure 11 It is a diagram showing the pass characteristics in the first embodiment and the fourth embodiment.

[0221] As Figure 11 shown, in the surface acoustic wave device of the fourth embodiment, similar to the first embodiment, filter characteristics can be obtained. In addition, near the frequency indicated by the arrow F in Figure 11 , compared with the first embodiment, the ripple caused by the unwanted wave in the fourth embodiment becomes smaller. Thus, in the fourth embodiment, the ripple in the frequency characteristics can be suppressed.

[0222] In the fourth embodiment, the duty ratios in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B are different from each other. Thus, the frequencies at which the unwanted waves are generated in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B are different from each other. Thus, in the fourth embodiment, the ripple in the frequency characteristics of the surface acoustic wave device can be suppressed.

[0223] Hereinafter, the structure of the fifth embodiment will be described. In the above-described first embodiment, the thicknesses of the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 of the first surface acoustic wave resonator 10A are the same as the thicknesses of the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 of the second surface acoustic wave resonator 10B. That is, when the thicknesses of the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 are set to te1 and the thicknesses of the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 of the second surface acoustic wave resonator 10B are set to te2, te1 = te2. On the other hand, in the fifth embodiment, te1 ≠ te2. Except for the above aspects, the surface acoustic wave device of the fifth embodiment is configured in the same manner as the surface acoustic wave device 10 of the first embodiment.

[0224] In addition, in this specification, the thicknesses of the electrode fingers being different from each other means that the absolute value of the difference between the thicknesses of the electrode fingers is 1% or more with respect to the thickness of any one of the electrode fingers. In the fifth embodiment, the thicknesses of the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 are the same. The thicknesses of the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 are the same.

[0225] In the first embodiment and the fifth embodiment, the filter characteristics are compared. The design parameters of the basic surface acoustic wave resonators of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the fifth embodiment are as follows.

[0226] Piezoelectric layer: The material is LiNbO 3 , the Euler angles (φ, ψ, θ) are (0°, 0°, 90°), and the thickness is 400 nm

[0227] The order of the first electrode finger to the third electrode finger represented by the connected potential: Repeats the order of IN, GND, OUT, GND.

[0228] The design parameters related to the electrode fingers in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B of the fifth embodiment are as follows.

[0229] First electrode finger to third electrode finger: The layer structure from the piezoelectric layer side is Ti layer / AlCu layer / Ti layer, the thickness from the piezoelectric layer side is 10 nm / 390 nm / 4 nm, and te1 is 404 nm

[0230] Fourth electrode finger to sixth electrode finger: The layer structure from the piezoelectric layer side is Ti layer / AlCu layer / Ti layer, the thickness from the piezoelectric layer side is 10 nm / 400 nm / 4 nm, and te2 is 414 nm

[0231] On the other hand, the design parameters of the basic elastic wave resonators of the first elastic wave resonator 10A and the second elastic wave resonator 10B in the first embodiment are set to be the same as those in the fifth embodiment. The design parameters related to the electrode fingers in the first elastic wave resonator 10A and the second elastic wave resonator 10B of the first embodiment are as follows.

[0232] First electrode finger to third electrode finger: The layer structure is a Ti layer / AlCu layer / Ti layer from the piezoelectric layer side, the thickness is 10 nm / 390 nm / 4 nm from the piezoelectric layer side, and te1 is 404 nm

[0233] Fourth electrode finger to sixth electrode finger: The layer structure is a Ti layer / AlCu layer / Ti layer from the piezoelectric layer side, the thickness is 10 nm / 390 nm / 4 nm from the piezoelectric layer side, and te2 is 404 nm

[0234] Figure 12 It is a diagram showing the passing characteristics in the first embodiment and the fifth embodiment.

[0235] As Figure 12 shown, in the elastic wave device of the fifth embodiment, similarly to the first embodiment, filter characteristics can be obtained. In addition, near the frequency indicated by the passing arrow F in Figure 12 , compared with the first embodiment, the ripple caused by the unwanted wave in the fifth embodiment becomes smaller. In this way, in the fifth embodiment, the ripple in the frequency characteristics can be suppressed.

[0236] In the fifth embodiment, te1 ≠ te2. As a result, in the first elastic wave resonator 10A and the second elastic wave resonator 10B, the frequencies at which unwanted waves are generated are different from each other. Therefore, in the fifth embodiment, the ripple in the frequency characteristics of the elastic wave device can be suppressed.

[0237] Hereinafter, the structure of the sixth embodiment will be described. In the above-described first embodiment, when the gap lengths of the gaps g1 and g2 in the first elastic wave resonator 10A are set to G1 and the gap lengths of the gaps g4 and g5 in the second elastic wave resonator 10B are set to G2, G1 = G2. On the other hand, in the sixth embodiment, G1 ≠ G2. In this specification, the fact that the gap lengths are different from each other means that the absolute value of the difference between the gap lengths divided by the electrode finger pitch is 0.02 or more. The electrode finger pitch mentioned here is the center-to-center distance p1 in the first elastic wave resonator 10A and the center-to-center distance p2 in the second elastic wave resonator 10B. In the case where p1 ≠ p2, the average value of the center-to-center distance p1 and the center-to-center distance p2 may be used as the above-mentioned electrode finger pitch. Except for the above aspects, the elastic wave device of the sixth embodiment is configured in the same manner as the elastic wave device 10 of the first embodiment.

[0238] In addition, in the sixth embodiment, the gap length G1 of the gap g1 and the gap length G1 of the gap g2 are the same. The gap length G2 of the gap g4 and the gap length G2 of the gap g5 are the same.

[0239] In the sixth embodiment, since G1 ≠ G2, the frequencies of the unwanted waves generated in the first elastic wave resonator 10A and the second elastic wave resonator 10B are different from each other. Thereby, it is possible to suppress the ripples caused by the unwanted waves in the frequency characteristics of the elastic wave device.

[0240] Hereinafter, the structure of the seventh embodiment will be described. In the above-described first embodiment, when the width of each electrode finger in the first elastic wave resonator 10A is set to w1 and the width of each electrode finger in the second elastic wave resonator 10B is set to w2, w1 = w2. In addition, specifically, each electrode finger in the first elastic wave resonator 10A is the first electrode finger 25, the second electrode finger 26, and the third electrode finger 27. Specifically, each electrode finger in the second elastic wave resonator 10B is the fourth electrode finger 35 as the first electrode finger, the fifth electrode finger 36 as the second electrode finger, and the sixth electrode finger 37 as the third electrode finger. On the other hand, in the seventh embodiment, w1 ≠ w2. Except for the above aspects, the elastic wave device of the seventh embodiment is configured in the same manner as the elastic wave device 10 of the first embodiment.

[0241] In addition, the width of the electrode finger is the dimension along the direction orthogonal to the electrode finger. In this specification, the fact that the widths of the electrode fingers are different from each other means that the absolute value of the difference between the widths of the electrode fingers is 1% or more with respect to the width of any one of the electrode fingers.

[0242] In the seventh embodiment, w1 ≠ w2, whereby in the first elastic wave resonator 10A and the second elastic wave resonator 10B, the frequencies at which spurious waves are generated are different from each other. Thereby, ripples due to spurious waves in the frequency characteristics of the elastic wave device can be suppressed.

[0243] Hereinafter, the structure of the eighth embodiment will be described. In the above-described first embodiment, when the dimension in the electrode finger extending direction of the crossover region E in the first elastic wave resonator 10A is defined as the crossover width Ap1 and the dimension in the electrode finger extending direction of the crossover region in the second elastic wave resonator 10B is defined as the crossover width Ap2, Ap1 = Ap2. On the other hand, in the eighth embodiment, Ap1 ≠ Ap2. In this specification, that the crossover widths are different from each other means that the absolute value of the difference between the crossover widths is 1% or more with respect to any one of the crossover widths. Except for the above aspects, the elastic wave device of the eighth embodiment is configured in the same manner as the elastic wave device 10 of the first embodiment.

[0244] In the eighth embodiment, Ap1 ≠ Ap2, whereby in the first elastic wave resonator 10A and the second elastic wave resonator 10B, the frequencies at which spurious waves are generated are different from each other. Thereby, ripples due to spurious waves in the frequency characteristics of the elastic wave device can be suppressed.

[0245] In the second to eighth embodiments, examples are shown in which one of a plurality of parameters is different between the first elastic wave resonator and the second elastic wave resonator. In addition, the structures of the second to eighth embodiments can also be adopted in other aspects of the present invention. That is, in the present invention, it may also be that at least one of the following parameters is different between the first elastic wave resonator and the second elastic wave resonator. Specifically, the above parameters are the total number of a plurality of electrode fingers, the center-to-center distance between adjacent electrode fingers, the duty ratio, the thickness of the electrode fingers, the gap length, the width of the electrode fingers, and the crossover width.

[0246] Figure 13 is a schematic front cross-sectional view of the first elastic wave resonator in the ninth embodiment. Figure 14 is a schematic front cross-sectional view of the second elastic wave resonator in the ninth embodiment.

[0247] As Figure 13 shown, the difference between this embodiment and the first embodiment is that the first elastic wave resonator 40A has a dielectric film 48A. As Figure 14 shown, the difference between this embodiment and the first embodiment is also that the second elastic wave resonator 40B has a dielectric film 48B. Except for the above aspects, the elastic wave device of this embodiment is configured in the same manner as the elastic wave device 10 of the first embodiment.

[0248] As Figure 13 shown, a dielectric film 48A is provided so as to cover the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 in the first surface acoustic wave resonator 40A. As Figure 14 shown, a dielectric film 48B is provided so as to cover the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 in the second surface acoustic wave resonator 40B.

[0249] As Figure 13 shown, each of the electrode fingers in the first surface acoustic wave resonator 40A has a first surface 11a, a second surface 11b, and a side surface 11c. The first surface 11a and the second surface 11b face each other in the thickness direction of the electrode finger. The second surface 11b of the first surface 11a and the second surface 11b is the surface on the piezoelectric layer 14 side. The side surface 11c is connected to the first surface 11a and the second surface 11b. In Figure 13 the example shown, the side surface 11c extends in parallel with the normal direction of the second surface 11b. In addition, the side surface 11c may extend obliquely with respect to the normal direction of the second surface 11b. The dielectric film 48A covers the first surface 11a and the side surface 11c of each electrode finger.

[0250] Similarly, as Figure 14 shown, the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 in the second surface acoustic wave resonator 40B have a first surface 31a, a second surface 31b, and a side surface 31c. The dielectric film 48B covers the first surface 31a and the side surface 31c of each electrode finger. In addition, it should be noted that each of the electrode fingers in each embodiment other than the ninth embodiment also has a first surface, a second surface, and a side surface.

[0251] In the present embodiment, when the thickness of the dielectric film 48A in the first surface acoustic wave resonator 40A is set to td1 and the thickness of the dielectric film 48B in the second surface acoustic wave resonator 40B is set to td2, td1≠td2. In addition, in the present specification, the thickness of the dielectric film means the distance between the first surface of the electrode finger and the surface of the dielectric film. Moreover, in the present specification, the fact that the thicknesses of the dielectric films are different from each other means that the absolute value of the difference between the thicknesses of the dielectric films is 1% or more with respect to the thickness of any one of the dielectric films.

[0252] In the present embodiment, the first surface acoustic wave resonator 40A and the second surface acoustic wave resonator 40B are respectively divided resonators obtained by serially dividing one surface acoustic wave resonator, and are acoustic coupling type filters. Thus, similarly to the first embodiment, when the surface acoustic wave device is used for a filter device, miniaturization of the filter device can be promoted, and the power resistance can be improved.

[0253] In addition, in the present embodiment, td1 ≠ td2, thereby making it possible to suppress the ripples caused by unwanted waves in the frequency characteristics. The following shows this effect.

[0254] In the first embodiment and the ninth embodiment, the filter characteristics were compared. The design parameters of the basic surface acoustic wave resonators of the first surface acoustic wave resonator 40A and the second surface acoustic wave resonator 40B in the ninth embodiment are as follows.

[0255] Piezoelectric layer: The material is LiNbO 3 , the Euler angles (φ, ψ, θ) are (0°, 0°, 90°), and the thickness is 400 nm

[0256] First electrode finger to third electrode finger: The layer structure from the piezoelectric layer side is a Ti layer / AlCu layer / Ti layer, and the thickness from the piezoelectric layer side is 10 nm / 390 nm / 4 nm

[0257] The order of the first electrode finger to the third electrode finger represented by the order of the connected potentials: Repeats the order of IN, GND, OUT, GND.

[0258] The thickness of the dielectric film in the first surface acoustic wave resonator 40A and the second surface acoustic wave resonator 40B in the ninth embodiment is as follows.

[0259] The thickness td1 of the dielectric film in the first surface acoustic wave resonator: 180 nm

[0260] The thickness td2 of the dielectric film in the second surface acoustic wave resonator: 178 nm

[0261] On the other hand, the design parameters of the basic surface acoustic wave resonators of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B in the first embodiment are set to be the same as those in the ninth embodiment. However, in the first embodiment, td1 = td2 = 0. That is, in the first embodiment, the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B do not have a dielectric film.

[0262] Figure 15 It is a diagram showing the passing characteristics in the first embodiment and the ninth embodiment.

[0263] As Figure 15 shown, in the surface acoustic wave device of the ninth embodiment, similar to the first embodiment, filter characteristics can be obtained. In addition, in Figure 15 the vicinity of the frequency indicated by the passing arrow F, compared with the first embodiment, the ripples caused by unwanted waves in the ninth embodiment are smaller. Thus, in the ninth embodiment, the ripples in the frequency characteristics can be suppressed.

[0264] In the ninth embodiment, td1 ≠ td2. As a result, in the first surface acoustic wave resonator 40A and the second surface acoustic wave resonator 40B, the frequencies at which spurious waves are generated are different from each other. Accordingly, in the ninth embodiment, ripples in the frequency characteristics of the surface acoustic wave device can be suppressed.

[0265] The structure in which td1 ≠ td2 in the ninth embodiment can also be adopted in the structures of the present invention other than the ninth embodiment. Alternatively, in the present invention, when both the first surface acoustic wave resonator and the second surface acoustic wave resonator have dielectric films, td1 = td2 may be used. However, td1 ≠ td2 is preferred. Accordingly, as described above, ripples in the frequency characteristics of the surface acoustic wave device can be suppressed.

[0266] Figure 16 It is a schematic plan view of the surface acoustic wave device according to the tenth embodiment. Figure 17 It is a schematic plan view of the second surface acoustic wave resonator in the tenth embodiment. In Figure 17 the wiring connected to the second surface acoustic wave resonator 50B and the like, and the first surface acoustic wave resonator 10A are omitted.

[0267] As Figure 16 and Figure 17 shown, the difference between this embodiment and the first embodiment is that the second surface acoustic wave resonator 50B has a pair of reflectors 53C and 53D. Except for the above aspects, the surface acoustic wave device of this embodiment is configured in the same manner as the surface acoustic wave device 10 of the first embodiment.

[0268] The reflectors 53C and 53D are provided on the first main surface 14a of the piezoelectric layer 14. The reflectors 53C and 53D face each other with the region where the fourth electrode fingers 35, the fifth electrode fingers 36, and the sixth electrode fingers 37 are provided interposed therebetween in the direction orthogonal to the electrodes. On the other hand, the first surface acoustic wave resonator 10A does not have a reflector.

[0269] As Figure 17 shown, the reflector 53C has a pair of reflector bus bars and a plurality of reflector electrode fingers 53c. Specifically, the pair of reflector bus bars are the first reflector bus bar 53a and the second reflector bus bar 53b. The first reflector bus bar 53a and the second reflector bus bar 53b face each other. One ends of the plurality of reflector electrode fingers 53c are respectively connected to the first reflector bus bar 53a. The other ends of the plurality of reflector electrode fingers 53c are respectively connected to the second reflector bus bar 53b. The reflector 53D is also configured in the same manner as the reflector 53C.

[0270] In the present embodiment, the first elastic wave resonator 10A and the second elastic wave resonator 50B are each a divided resonator obtained by serially dividing one elastic wave resonator, and are acoustic coupling type filters. Thus, similarly to the first embodiment, when the elastic wave device is used for a filter device, miniaturization of the filter device can be promoted, and power resistance can be improved.

[0271] Alternatively, the first elastic wave resonator 10A may have a pair of reflectors, and the second elastic wave resonator 50B may not have reflectors. In this case, when the elastic wave device is used for a filter device, miniaturization of the filter device can also be promoted, and power resistance can be improved.

[0272] On the other hand, in Figure 18 a modified example of the tenth embodiment shown, the first elastic wave resonator 50A has a pair of reflectors 53A and 53B. The reflectors 53A and 53B face each other with the region where the first electrode fingers 25, the second electrode fingers 26, and the third electrode fingers 27 are provided therebetween in the direction orthogonal to the electrode fingers. Similarly to the tenth embodiment, the second elastic wave resonator 50B has a pair of reflectors 53C and 53D. In addition, the reflectors 53A and 53B in the first elastic wave resonator 50A are configured in the same manner as the reflector 53C in the second elastic wave resonator 50B. In this modified example, when the elastic wave device is used for a filter device, miniaturization of the filter device can also be promoted, and power resistance can be improved.

[0273] In the first embodiment, the tenth embodiment, and the modified example of the tenth embodiment, the filter characteristics were compared. The design parameters of the basic elastic wave resonators of the first elastic wave resonator 10A and the second elastic wave resonator 50B in the tenth embodiment are as follows.

[0274] Piezoelectric layer: The material is LiNbO 3 , the Euler angles (φ, ψ, θ) are (0°, 0°, 90°), and the thickness is 400 nm

[0275] First electrode finger to third electrode finger: The layer structure from the piezoelectric layer side is a Ti layer / AlCu layer / Ti layer, and the thickness from the piezoelectric layer side is 10 nm / 390 nm / 4 nm

[0276] The order of the first electrode finger to the third electrode finger represented by the order of the connected potentials: Repeats the order of IN, GND, OUT, GND.

[0277] On the other hand, the design parameters of the modified examples of the first embodiment and the tenth embodiment are set to be the same as those of the tenth embodiment. However, in the first embodiment, the first elastic wave resonator 10A and the second elastic wave resonator 10B do not have reflectors. On the other hand, in the modified example of the tenth embodiment, the first elastic wave resonator 50A and the second elastic wave resonator 50B each have a pair of reflectors.

[0278] Figure 19 FIG. is a diagram showing the passing characteristics in the first embodiment and the tenth embodiment. Figure 20 FIG. is a diagram showing the passing characteristics in the tenth embodiment and its modified example.

[0279] As Figure 19 shown, in the elastic wave device of the tenth embodiment, similar to the first embodiment, filter characteristics can be obtained. In addition, in the tenth embodiment, near the center of the passband, the loss can be reduced. On the other hand, in the first embodiment, since no reflector is provided, the elastic wave device 10 can be made small.

[0280] As Figure 20 shown, in the elastic wave device of the modified example of the tenth embodiment, similar to the tenth embodiment, filter characteristics can be obtained. In the modified example, near the center of the passband, the loss can be effectively reduced. On the other hand, in the tenth embodiment, compared with the modified example, in the low-frequency side of the passband, the ripple caused by the unwanted wave becomes smaller.

[0281] In addition, the structure in which at least one of the first elastic wave resonator and the second elastic wave resonator has a pair of reflectors can also be adopted in the embodiments of the present invention other than the tenth embodiment and its modified example. However, it is preferable that one of the first elastic wave resonator and the second elastic wave resonator has a pair of reflectors. Thereby, similar to the tenth embodiment, the ripple on the low-frequency side of the passband can be suppressed, and the loss near the center of the passband can be reduced.

[0282] In the present invention, the first elastic wave resonator and the second elastic wave resonator may also be configured to be able to utilize plate waves. In this case, similar to Figure 18 the modified example of the tenth embodiment shown, it is sufficient that the first elastic wave resonator and the second elastic wave resonator each have a pair of reflectors.

[0283] Figure 21 FIG. is a schematic top view of the elastic wave device according to the eleventh embodiment.

[0284] The difference between this embodiment and the first embodiment is that an elastic wave resonator is divided in parallel. In this embodiment, the first elastic wave resonator 10A and the second elastic wave resonator 10B are each divided resonator obtained by dividing an elastic wave resonator in parallel. Except for the above aspects, the elastic wave device 60 of this embodiment is configured in the same manner as the elastic wave device 10 of the first embodiment.

[0285] Similar to the first embodiment, the first elastic wave resonator 10A and the second elastic wave resonator 10B are acoustic coupling type filters. Thus, in each of the first elastic wave resonator 10A and the second elastic wave resonator 10B, a filter waveform can be obtained. Therefore, when the elastic wave device 60 is used in a filter device, even if the number of elastic wave resonators constituting the filter device is small, a filter waveform can be appropriately obtained. Therefore, miniaturization of the filter device can be promoted.

[0286] In addition, compared with the case of a single elastic wave resonator, by providing the first elastic wave resonator 10A and the second elastic wave resonator 10B which are divided in parallel, the heat dissipation path can be increased. Thus, when the elastic wave device operates, it is possible to suppress the temperature of the first elastic wave resonator 10A and the second elastic wave resonator 10B from becoming too high, and the first elastic wave resonator 10A and the second elastic wave resonator 10B are less likely to be damaged. Therefore, the power resistance can be improved.

[0287] Hereinafter, the structure of this embodiment will be described in more detail.

[0288] A first signal potential wiring 28A, a second signal potential wiring 28B, and a reference potential wiring 28C are provided on the first main surface 14a of the piezoelectric layer 14. The first signal potential wiring 28A is connected to an input potential. The second signal potential wiring 28B is connected to an output potential. The reference potential wiring 28C is connected to a reference potential.

[0289] The first bus bar 22 of the first elastic wave resonator 10A and the fourth bus bar 32 of the second elastic wave resonator 10B are commonly connected to the first signal potential wiring 28A. The first elastic wave resonator 10A and the second elastic wave resonator 10B are connected to the same input potential via the first signal potential wiring 28A.

[0290] The second bus bar 23 of the first elastic wave resonator 10A and the fifth bus bar 33 of the second elastic wave resonator 10B are commonly connected to the second signal potential wiring 28B. The first elastic wave resonator 10A and the second elastic wave resonator 10B are connected to the same output potential via the second signal potential wiring 28B. In this way, the first elastic wave resonator 10A and the second elastic wave resonator 10B are connected in parallel with each other.

[0291] In this embodiment, the third bus bar 24 of the first surface acoustic wave resonator 10A and the sixth bus bar 34 of the second surface acoustic wave resonator 10B are formed integrally. The third bus bar 24 and the sixth bus bar 34 are connected to the reference potential via the reference potential wiring 28C. Thereby, the wiring can be simplified, and the miniaturization of the filter device can be effectively promoted. In addition, the third bus bar 24 and the sixth bus bar 34 do not necessarily have to be formed integrally.

[0292] The first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B are arranged in a direction orthogonal to the electrode fingers. However, the arrangement of the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B is not limited to the above arrangement. As long as the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B are connected in parallel with each other.

[0293] Figure 22 It is along Figure 21 a schematic cross-sectional view taken along line II-II in

[0294] A cavity portion 10a and a cavity portion 10b are independently provided in the piezoelectric substrate 12. The first electrode finger 25, the second electrode finger 26, and the third electrode finger 27 in the first surface acoustic wave resonator 10A overlap the cavity portion 10a in a plan view. The fourth electrode finger 35 as the first electrode finger, the fifth electrode finger 36 as the second electrode finger, and the sixth electrode finger 37 as the third electrode finger in the second surface acoustic wave resonator 10B overlap the cavity portion 10b in a plan view.

[0295] In addition, the cavity portion 10a and the cavity portion 10b may be provided integrally. The first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B may share the same cavity portion.

[0296] In this embodiment, the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B are respectively divided resonators obtained by dividing one surface acoustic wave resonator in parallel. In this case, similar to the second to eighth embodiments, in the first surface acoustic wave resonator 10A and the second surface acoustic wave resonator 10B, at least one of the following parameters is different from each other. Specifically, the above parameters are the total number of the plurality of electrode fingers, the center-to-center distance between adjacent electrode fingers, the duty ratio, the thickness of the electrode fingers, the gap length, the width of the electrode fingers, and the crossover width. Thereby, ripples caused by unwanted waves can be suppressed in the frequency characteristics of the surface acoustic wave device 60.

[0297] Similarly to the ninth embodiment, the first elastic wave resonator 10A and the second elastic wave resonator 10B have dielectric films. In this case, it is preferable that the relationship between the thickness td1 of the dielectric film in the first elastic wave resonator 10A and the thickness td2 of the dielectric film in the second elastic wave resonator 10B is td1≠td2. Thereby, ripples caused by unwanted waves can be suppressed in the frequency characteristics of the elastic wave device 60.

[0298] Alternatively, similarly to the tenth embodiment or its modification, at least one of the first elastic wave resonator 10A and the second elastic wave resonator 10B has a pair of reflectors. Preferably, one of the first elastic wave resonator 10A and the second elastic wave resonator 10B has a pair of reflectors. Thereby, ripples on the low-frequency side of the passband can be suppressed, and the loss near the center of the passband can be reduced.

[0299] Similarly to the modification of the first embodiment, the third electrode 19 of the first elastic wave resonator 10A and the sixth electrode of the second elastic wave resonator 10B have a meandering shape. In this case, the first elastic wave resonator 10A and the second elastic wave resonator 10B may be divided resonators obtained by parallel-dividing one elastic wave resonator.

[0300] Figure 23 It is a schematic top view of the elastic wave device according to the twelfth embodiment.

[0301] The difference between this embodiment and the eleventh embodiment is that the first elastic wave resonator 70A and the second elastic wave resonator 70B have reflectors. Except for the above aspects, the elastic wave device of this embodiment is configured in the same manner as the elastic wave device 60 of the eleventh embodiment. In addition, as Figure 23 shown, the first elastic wave resonator 70A and the second elastic wave resonator 70B are arranged in the direction orthogonal to the electrode fingers.

[0302] The first elastic wave resonator 70A has a first reflector 73A. The second elastic wave resonator 70B has a second reflector 73D. The first elastic wave resonator 70A and the second elastic wave resonator 70B share a third reflector 73E. The first reflector 73A, the second reflector 73D, and the third reflector 73E are provided on the first main surface 14a of the piezoelectric layer 14.

[0303] The third reflector 73E is disposed between the region where a plurality of electrode fingers of the first elastic wave resonator 70A are provided and the region where a plurality of electrode fingers of the second elastic wave resonator 70B are provided. Specifically, the region where a plurality of electrode fingers of the first elastic wave resonator 70A are provided is the region where the first electrode finger 25, the second electrode finger 26, and the third electrode finger 27 are provided. Specifically, the region where a plurality of electrode fingers of the second elastic wave resonator 70B are provided is the region where the fourth electrode finger 35 as the first electrode finger, the fifth electrode finger 36 as the second electrode finger, and the sixth electrode finger 37 as the third electrode finger are provided.

[0304] The first reflector 73A and the third reflector 73E are opposed to each other with the region where a plurality of electrode fingers of the first elastic wave resonator 70A are provided interposed therebetween in the direction orthogonal to the electrode fingers. The second reflector 73D and the third reflector 73E are opposed to each other with the region where a plurality of electrode fingers of the second elastic wave resonator 70B are provided interposed therebetween in the direction orthogonal to the electrode fingers.

[0305] The first reflector 73A is configured in the same manner as the reflector 53A in the tenth embodiment. Specifically, the first reflector 73A has a first reflector bus bar, a second reflector bus bar, and a plurality of reflector electrode fingers. The same applies to the second reflector 73D and the third reflector 73E.

[0306] In the present embodiment, by providing the first reflector 73A, the second reflector 73D, and the third reflector 73E, it is possible to reduce the loss in the passband. In addition, by sharing the third reflector 73E between the first elastic wave resonator 70A and the second elastic wave resonator 70B, the elastic wave device can be made smaller.

[0307] Furthermore, the first elastic wave resonator 70A and the second elastic wave resonator 70B are each a divided resonator obtained by parallel-dividing one elastic wave resonator, and are acoustic coupling type filters. Thus, in the same manner as in the eleventh embodiment, when the elastic wave device is used for a filter device, it is possible to promote the miniaturization of the filter device and improve the power resistance.

[0308] As Figure 23 shown, the cavity portion 10a and the cavity portion 10b are provided independently. However, the cavity portion 10a and the cavity portion 10b may be provided integrally. The first elastic wave resonator 70A and the second elastic wave resonator 70B may also share the same cavity portion. In this case, it is possible to more reliably arrange all the reflector electrode fingers in the third reflector 73E to overlap the cavity portion in a plan view. Therefore, it is possible to more reliably improve the resonance characteristics of the first elastic wave resonator 70A and the second elastic wave resonator 70B.

[0309] Figure 24 It is a schematic top view of the surface acoustic wave device according to the 13th embodiment. Figure 25 It is a schematic front cross-sectional view showing the vicinity of the first to third electrode fingers of the first surface acoustic wave resonator in the 13th embodiment.

[0310] As Figure 24 and Figure 25 shown, the difference between this embodiment and the first embodiment is that the third electrode 19 in the first surface acoustic wave resonator 80A is provided on the second main surface 14b of the piezoelectric layer 14. As Figure 24 shown, the difference between this embodiment and the first embodiment is also that the sixth electrode 39 in the second surface acoustic wave resonator 80B is provided on the second main surface 14b of the piezoelectric layer 14. Further, the difference between this embodiment and the first embodiment is also that the reference potential wiring 28C is provided on the second main surface 14b of the piezoelectric layer 14. Except for the above aspects, the surface acoustic wave device of this embodiment has the same structure as the surface acoustic wave device 10 of the first embodiment.

[0311] The arrangement of the third electrode 19 in the first surface acoustic wave resonator 80A in a top view is the same as the arrangement of the third electrode 19 in the first surface acoustic wave resonator 10A of the first embodiment. Specifically, in the first surface acoustic wave resonator 80A, a plurality of third electrode fingers 27 are respectively provided on the second main surface 14b of the piezoelectric layer 14 so as to be arranged in the direction in which the first electrode finger 25 and the second electrode finger 26 are arranged in a top view and to be arranged with the first electrode finger 25 and the second electrode finger 26. In a top view, when starting from the first electrode finger 25, the order of arrangement of the plurality of electrode fingers is the order of taking the first electrode finger 25, the third electrode finger 27, the second electrode finger 26, and the third electrode finger 27 as one cycle.

[0312] The arrangement of the sixth electrode 39 in the second surface acoustic wave resonator 80B in a top view is the same as the arrangement of the sixth electrode 39 in the second surface acoustic wave resonator 10B of the first embodiment. Specifically, in the second surface acoustic wave resonator 80B, a plurality of sixth electrode fingers 37 are respectively provided on the second main surface 14b of the piezoelectric layer 14 so as to be arranged in the direction in which the fourth electrode finger 35 and the fifth electrode finger 36 are arranged in a top view and to be arranged with the fourth electrode finger 35 and the fifth electrode finger 36. In a top view, when starting from the fourth electrode finger 35, the order of arrangement of the plurality of electrode fingers is the order of taking the fourth electrode finger 35, the sixth electrode finger 37, the fifth electrode finger 36, and the sixth electrode finger 37 as one cycle.

[0313] The reference potential wiring 28C is provided on the second main surface 14b of the piezoelectric layer 14. The third bus bar 24 in the third electrode 19 of the first surface acoustic wave resonator 80A is connected to the reference potential wiring 28C. The sixth bus bar 34 in the sixth electrode 39 of the second surface acoustic wave resonator 80B is connected to the reference potential wiring 28C.

[0314] The first surface acoustic wave resonator 80A and the second surface acoustic wave resonator 80B are each a split resonator obtained by serially splitting one surface acoustic wave resonator, and are acoustic coupling type filters. Thus, similarly to the first embodiment, when the surface acoustic wave device is used for a filter device, miniaturization of the filter device can be promoted and power resistance can be improved.

[0315] Alternatively, the first surface acoustic wave resonator 80A and the second surface acoustic wave resonator 80B may each be a split resonator obtained by parallely splitting one surface acoustic wave resonator. In this case, similarly to the eleventh embodiment and the like, when the surface acoustic wave device is used for a filter device, miniaturization of the filter device can be promoted and power resistance can be improved.

[0316] Hereinafter, the thickness shear mode will be described in detail using an example in which the functional electrode is an IDT electrode. The "electrode" in the IDT electrode described later corresponds to an electrode finger. The surface acoustic wave device in the following example is one surface acoustic wave resonator. The support member in the following example corresponds to the support substrate in the present invention. Hereinafter, the reference potential may sometimes be referred to as the ground potential.

[0317] Figure 26 FIG. (a) is a schematic perspective view showing the appearance of a surface acoustic wave device using a body wave of the thickness shear mode, Figure 26 FIG. (b) is a plan view showing the electrode structure on the piezoelectric layer, Figure 27 is Figure 26 A cross-sectional view of a portion along line A-A in FIG. (a).

[0318] The surface acoustic wave device 1 includes a piezoelectric layer 2 containing LiNbO 3 The piezoelectric layer 2 may also contain LiTaO 3 LiNbO 3 LiTaO 3The cutting angle is Z-cut, but it can also be rotated Y-cut or X-cut. The thickness of the piezoelectric layer 2 is not particularly limited, but in order to effectively excite the thickness-shear mode, it is preferably 40 nm or more and 1000 nm or less, more preferably 50 nm or more and 1000 nm or less. The piezoelectric layer 2 has a first main surface 2a and a second main surface 2b that face each other. An electrode 3 and an electrode 4 are provided on the first main surface 2a. Here, the electrode 3 is an example of the "first electrode", and the electrode 4 is an example of the "second electrode". In Figure 26 of (a) and Figure 26 of (b), a plurality of electrodes 3 are connected to the first bus bar 5. A plurality of electrodes 4 are connected to the second bus bar 6. The plurality of electrodes 3 and the plurality of electrodes 4 are interlaced with each other. The electrodes 3 and 4 have a rectangular shape and have a length direction. In a direction orthogonal to the length direction, the electrode 3 faces the adjacent electrode 4. The length direction of the electrodes 3 and 4 and the direction orthogonal to the length direction of the electrodes 3 and 4 are both directions that cross the thickness direction of the piezoelectric layer 2. Therefore, it can also be said that the electrode 3 and the adjacent electrode 4 face each other in a direction that crosses the thickness direction of the piezoelectric layer 2. In addition, the length direction of the electrodes 3 and 4 can also be Figure 26 of (a) and Figure 26 of (b) shown swapped with the direction orthogonal to the length direction of the electrodes 3 and 4. That is, in Figure 26 of (a) and Figure 26 of (b), the electrodes 3 and 4 can also extend in the direction in which the first bus bar 5 and the second bus bar 6 extend. In this case, the first bus bar 5 and the second bus bar 6 are in Figure 26 of (a) and Figure 26In (b) thereof, it will extend in the direction in which electrodes 3 and 4 extend. Moreover, multiple pairs of configurations in which the electrode 3 connected to one potential and the electrode 4 connected to the other potential are adjacent are provided in the direction orthogonal to the length direction of the above electrodes 3 and 4. Here, the so-called adjacent electrodes 3 and 4 do not refer to the case where electrodes 3 and 4 are arranged in direct contact, but refer to the case where electrodes 3 and 4 are arranged at intervals. In addition, when electrodes 3 and 4 are adjacent, no electrode connected to a signal (hot) electrode or a ground electrode including other electrodes 3 and 4 is arranged between electrodes 3 and 4. This number of pairs does not need to be an integer pair and can also be 1.5 pairs, 2.5 pairs, etc. The center-to-center distance (i.e., pitch) between electrodes 3 and 4 is preferably in the range of 1 μm or more and 10 μm or less. In addition, the width of electrodes 3 and 4 (i.e., the dimension in the facing direction of electrodes 3 and 4) is preferably in the range of 50 nm or more and 1000 nm or less, and more preferably in the range of 150 nm or more and 1000 nm or less. In addition, the so-called center-to-center distance between electrodes 3 and 4 is the distance connecting the center of the dimension (width dimension) of electrode 3 in the direction orthogonal to the length direction of electrode 3 and the center of the dimension (width dimension) of electrode 4 in the direction orthogonal to the length direction of electrode 4.

[0319] In addition, in the elastic wave device 1, since a Z-cut piezoelectric layer is used, the direction orthogonal to the length direction of electrodes 3 and 4 becomes the direction orthogonal to the polarization direction of the piezoelectric layer 2. This is not limited when using a piezoelectric body with other cut angles as the piezoelectric layer 2. Here, the so-called "orthogonal" is not limited to the case of strictly orthogonal, and can also be approximately orthogonal (the angle formed by the direction orthogonal to the length direction of electrodes 3 and 4 and the polarization direction is, for example, in the range of 90° ± 10°).

[0320] On the second main surface 2b side of the piezoelectric layer 2, a support member 8 is laminated with an insulating layer 7 interposed therebetween. The insulating layer 7 and the support member 8 have a frame shape and, as Figure 27 shown, have through holes 7a and 8a. Thereby, a cavity portion 9 is formed. The cavity portion 9 is provided so as not to hinder the vibration of the excitation region C of the piezoelectric layer 2. Therefore, the above support member 8 is laminated on the second main surface 2b with the insulating layer 7 interposed therebetween at a position not overlapping with the portion where at least one pair of electrodes 3 and 4 is provided. In addition, the insulating layer 7 may not be provided. Therefore, the support member 8 can be laminated directly or indirectly on the second main surface 2b of the piezoelectric layer 2.

[0321] The insulating layer 7 contains silicon oxide. However, in addition to silicon oxide, appropriate insulating materials such as silicon oxynitride and alumina can also be used. The support member 8 contains Si. The plane orientation of the surface of the Si on the piezoelectric layer 2 side can be (100), (110), or (111). The Si constituting the support member 8 is preferably a high-resistance with a resistivity of 4 kΩ·cm or more. However, for the support member 8, appropriate insulating materials or semiconductor materials can also be used for its constitution.

[0322] As the material of the support member 8, for example, piezoelectric bodies such as alumina, lithium tantalate, lithium niobate, and quartz, various ceramics such as alumina, magnesia, sapphire, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, steatite, and forsterite, dielectrics such as diamond and glass, and semiconductors such as gallium nitride can be used.

[0323] The above-mentioned plurality of electrodes 3, 4 and the first bus bar 5, the second bus bar 6 contain appropriate metals or alloys such as Al and AlCu alloy. In the elastic wave device 1, the electrodes 3, 4 and the first bus bar 5, the second bus bar 6 have a structure in which an Al film is laminated on a Ti film. In addition, an adhesion layer other than the Ti film can also be used.

[0324] During driving, an alternating voltage is applied between the plurality of electrodes 3 and the plurality of electrodes 4. More specifically, an alternating voltage is applied between the first bus bar 5 and the second bus bar 6. Thereby, the resonance characteristics of the bulk wave using the thickness-shear mode excited in the piezoelectric layer 2 can be obtained. In addition, in the elastic wave device 1, when the thickness of the piezoelectric layer 2 is set to d and the center-to-center distance between any adjacent electrodes 3, 4 in the plurality of pairs of electrodes 3, 4 is set to p, d / p is set to 0.5 or less. Therefore, the bulk wave of the above-mentioned thickness-shear mode can be effectively excited, and good resonance characteristics can be obtained. More preferably, d / p is 0.24 or less, and in this case, better resonance characteristics can be obtained.

[0325] In the elastic wave device 1, with the above structure, even if the number of pairs of electrodes 3, 4 is reduced in order to achieve miniaturization, a decrease in the Q value is not likely to occur. This is because even if the number of electrode fingers in the reflectors on both sides is reduced, the propagation loss is small. In addition, the reason why the number of the above-mentioned electrode fingers can be reduced is that the bulk wave of the thickness-shear mode is utilized. Refer to Figure 28 of (a) and Figure 28 of (b) to explain the differences between the Lamb wave and the above-mentioned bulk wave of the thickness-shear mode used in the elastic wave device.

[0326] Figure 28FIG. (a) is a schematic front cross-sectional view for explaining Lamb waves propagating in a piezoelectric film of a surface acoustic wave device as described in Japanese Patent Laid-Open Publication No. 2012-257019. Here, waves propagate in the piezoelectric film 201 as indicated by the arrows. Here, in the piezoelectric film 201, a first main surface 201a and a second main surface 201b face each other, and the thickness direction connecting the first main surface 201a and the second main surface 201b is the Z direction. The X direction is the direction in which the electrode fingers of the IDT electrode are arranged. As Figure 28 shown in FIG. (a), in the case of Lamb waves, the waves propagate in the X direction as shown in the figure. Since it is a plate wave, the piezoelectric film 201 vibrates as a whole. Nevertheless, since the waves propagate in the X direction, reflectors are arranged on both sides to obtain resonance characteristics. Therefore, propagation loss of the waves occurs. In the case of pursuing miniaturization, that is, when the number of electrode fingers is reduced, the Q value decreases.

[0327] In contrast, as Figure 28 shown in FIG. (b), in the surface acoustic wave device 1, the vibration displacement is in the thickness-shear direction. Therefore, the waves basically propagate and resonate in the direction connecting the first main surface 2a and the second main surface 2b of the piezoelectric layer 2 (that is, the Z direction). That is, the X-direction component of the waves is significantly smaller than the Z-direction component. Moreover, since the resonance characteristics are obtained by the propagation of the waves in the Z direction, even if the number of electrode fingers of the reflector is reduced, propagation loss is not easily generated. Furthermore, even if the number of electrode pairs including the electrodes 3 and 4 is reduced in order to promote miniaturization, a decrease in the Q value is not easily generated.

[0328] In addition, as Figure 29 shown, the amplitude directions of the bulk waves in the thickness-shear mode become opposite in a first region 451 included in the excitation region C of the piezoelectric layer 2 and a second region 452 included in the excitation region C. In Figure 29 , a bulk wave is schematically shown in the case where a voltage is applied between the electrode 3 and the electrode 4 such that the electrode 4 is at a higher potential than the electrode 3. The first region 451 is a region between the imaginary plane VP1 in the excitation region C and the first main surface 2a, where the imaginary plane VP1 is orthogonal to the thickness direction of the piezoelectric layer 2 and divides the piezoelectric layer 2 into two parts. The second region 452 is a region between the imaginary plane VP1 in the excitation region C and the second main surface 2b.

[0329] As described above, in the surface acoustic wave device 1, at least one pair of electrodes including the electrodes 3 and 4 is arranged. However, since the waves do not propagate in the X direction, the number of electrode pairs including the electrodes 3 and 4 does not need to be multiple pairs. That is, it is sufficient to provide at least one pair of electrodes.

[0330] For example, the above-mentioned electrode 3 is an electrode connected to the signal (hot) potential, and the electrode 4 is an electrode connected to the ground potential. However, it is also possible that the electrode 3 is connected to the ground potential and the electrode 4 is connected to the signal potential. In the elastic wave device 1, at least one pair of electrodes is an electrode connected to the signal potential or an electrode connected to the ground potential as described above, and no floating electrode is provided.

[0331] Figure 30 is a diagram showing Figure 27 the resonance characteristics of the elastic wave device shown. In addition, the design parameters of the elastic wave device 1 for which such resonance characteristics are obtained are as follows.

[0332] Piezoelectric layer 2: LiNbO with Euler angles of (0°, 0°, 90°) 3 , thickness = 400 nm.

[0333] When observed in a direction orthogonal to the length directions of the electrodes 3 and 4, the length of the region where the electrodes 3 and 4 overlap (i.e., the excitation region C) = 40 μm, the number of pairs of electrodes including the electrodes 3 and 4 = 21 pairs, the center distance between electrodes = 3 μm, the widths of the electrodes 3 and 4 = 500 nm, d / p = 0.133.

[0334] Insulating layer 7: A silicon oxide film with a thickness of 1 μm.

[0335] Support member 8: Si.

[0336] In addition, the length of the excitation region C refers to the dimension of the excitation region C along the length directions of the electrodes 3 and 4.

[0337] In the elastic wave device 1, the distance between electrodes of the electrode pairs including the electrodes 3 and 4 is set to be equal for all in multiple pairs. That is, the electrodes 3 and 4 are arranged at equal intervals.

[0338] According to Figure 30 it is clear that, although not having a reflector, good resonance characteristics with a relative bandwidth of 12.5% are still obtained.

[0339] In addition, when the thickness of the above-mentioned piezoelectric layer 2 is set to d and the center distance between the electrodes 3 and 4 is set to p, as described above, in the elastic wave device 1, d / p is 0.5 or less, and more preferably 0.24 or less. Refer to Figure 31 for an explanation of this.

[0340] Similar to the elastic wave device for which Figure 30 the resonance characteristics shown are obtained, but by varying d / p, a plurality of elastic wave devices are obtained. Figure 31 is a diagram showing the relationship between this d / p and the relative bandwidth of the elastic wave device as a resonator.

[0341] According to Figure 31 It can be clarified that if d / p > 0.5, even if d / p is adjusted, the relative bandwidth is less than 5%. In contrast, when d / p ≤ 0.5, if d / p is changed within this range, the relative bandwidth can be made 5% or more, that is, a resonator with a high coupling coefficient can be formed. In addition, when d / p is 0.24 or less, the relative bandwidth can be increased to 7% or more. In addition to this, if d / p is adjusted within this range, a resonator with a wider relative bandwidth can be obtained, and a resonator with a higher coupling coefficient can be realized. Therefore, it can be known that by setting d / p to 0.5 or less, a resonator with a high coupling coefficient utilizing the bulk wave of the above-mentioned thickness shear mode can be formed.

[0342] Figure 32 is a top view of an elastic wave device using a bulk wave of the thickness shear mode. In the elastic wave device 90, a pair of electrodes having an electrode 3 and an electrode 4 are provided on the first main surface 2a of the piezoelectric layer 2. In addition, Figure 32 K in becomes the crossover width. As described above, in the elastic wave device of the present invention, the number of pairs of electrodes may also be one pair. In this case, as long as the above d / p is 0.5 or less, the bulk wave of the thickness shear mode can be effectively excited.

[0343] In the elastic wave device 1, preferably, among the plurality of electrodes 3 and 4, the metallization ratio MR of any adjacent electrodes 3 and 4 with respect to the excitation region C preferably satisfies MR ≤ 1.75(d / p) + 0.075, where the excitation region C is the region where the adjacent electrodes 3 and 4 overlap when viewed in the opposing direction. In this case, spurious can be effectively reduced. Refer to Figure 33 and Figure 34 This will be described. Figure 33 is a reference diagram showing an example of the resonance characteristics of the above-mentioned elastic wave device 1. Spurious indicated by an arrow B appears between the resonance frequency and the anti-resonance frequency. In addition, let d / p = 0.08, and let the Euler angles of LiNbO 3 be (0°, 0°, 90°). In addition, let the above-mentioned metallization ratio MR = 0.35.

[0344] Refer to Figure 26 The (b) of to describe the metallization ratio MR. In Figure 26In the electrode structure of (b), when focusing on a pair of electrodes 3 and 4, assume that only this pair of electrodes 3 and 4 are provided. In this case, the portion surrounded by the single-dot chain line becomes the excitation region C. The so-called excitation region C is the region where electrode 3 overlaps with electrode 4, the region where electrode 4 overlaps with electrode 3, and the region where electrode 3 and electrode 4 overlap in the region between electrode 3 and electrode 4 when observing electrode 3 and electrode 4 in the direction orthogonal to the length direction of electrodes 3 and 4 (i.e., the facing direction). Moreover, the area of electrodes 3 and 4 within the excitation region C with respect to the area of the excitation region C becomes the metallization ratio MR. That is, the metallization ratio MR is the ratio of the area of the metallized portion to the area of the excitation region C.

[0345] In addition, in the case where multiple pairs of electrodes are provided, it is only necessary to use the ratio of the total area of the metallized portions included in all the excitation regions to the area of the excitation regions as MR.

[0346] Figure 34 It is a graph showing the relationship between the relative bandwidth and the phase rotation amount of the spurious impedance normalized by 180 degrees, which is the size of the spurious, in the case where many elastic wave resonators are configured according to the structure of the elastic wave device 1. In addition, regarding the relative bandwidth, the film thickness of the piezoelectric layer and the size of the electrodes were variously changed and adjusted. In addition, Figure 34 is the result in the case of using a piezoelectric layer containing Z-cut LiNbO 3 However, even in the case of using a piezoelectric layer with other cut angles, the same tendency is obtained.

[0347] In Figure 34 In the region surrounded by the ellipse J, the spurious becomes as large as 1.0. According to Figure 34 it can be clarified that if the relative bandwidth exceeds 0.17, that is, if it exceeds 17%, large spurious with a spurious level of 1 or more will appear in the passband even if the parameters constituting the relative bandwidth are changed. That is, like the resonance characteristics shown in Figure 33 large spurious shown by the arrow B appears in the band. Therefore, the relative bandwidth is preferably 17% or less. In this case, by adjusting the film thickness of the piezoelectric layer 2, the sizes of the electrodes 3 and 4, etc., the spurious can be reduced.

[0348] Figure 35 is a graph showing the relationship between d / 2p, the metallization ratio MR, and the relative bandwidth. Various elastic wave devices with different d / 2p and MR in the above elastic wave device were constructed, and the relative bandwidth was measured. Figure 35The hatched portion on the right side of the dashed line D is a region with a relative bandwidth of 17% or less. The boundary between the hatched region and the non-hatched region can be expressed by MR = 3.5(d / 2p) + 0.075. That is, MR = 1.75(d / p) + 0.075. Therefore, it is preferable that MR ≤ 1.75(d / p) + 0.075. In this case, it is easy to make the relative bandwidth 17% or less. More preferably, it is Figure 35 the region on the right side of MR = 3.5(d / 2p) + 0.05 shown by the dash-dot line D1 in

[0349] Figure 36 a graph showing the mapping of the relative bandwidth with respect to the Euler angles (0°, θ, ψ) of LiNbO when d / p approaches 0 infinitely. In 3 each of the hatched regions R shown in Figure 36 is a region where a relative bandwidth of 2% or more can be obtained. In addition, when φ in the Euler angles (φ, θ, ψ) is in the range of 0° ± 5°, the relationship between θ and ψ and the relative bandwidth is the same as that shown in Figure 36 Even when the piezoelectric layer contains lithium tantalate (LiTaO 3 ), the relationship between θ and ψ and BW in the Euler angles (in the range of 0° ± 5°, θ, ψ) is also the same as that shown in Figure 36 Therefore, if φ in the Euler angles (φ, θ, ψ) of lithium niobate or lithium tantalate constituting the piezoelectric layer is in the range of 0° ± 5°, and θ and φ are in any of the

[0350] multiple regions R shown in Figure 36 it is preferable because the relative bandwidth can be made sufficiently wide.

[0351] Figure 37 is a front cross-sectional view of an elastic wave device having a multilayer acoustic film.

[0352] In the elastic wave device 91, a piezoelectric multilayer film 92 is stacked on the second main surface 2b of the piezoelectric layer 2. The piezoelectric multilayer film 92 has a stacked structure including low acoustic impedance layers 92a, 92c, 92e with relatively low acoustic impedance and high acoustic impedance layers 92b, 92d with relatively high acoustic impedance. When the piezoelectric multilayer film 92 is used, even without using the cavity portion 9 in the elastic wave device 1, the bulk wave of the thickness-shear mode can be confined within the piezoelectric layer 2. In the elastic wave device 91, by setting the above d / p to 0.5 or less, the resonance characteristics based on the bulk wave of the thickness-shear mode can also be obtained. In addition, in the piezoelectric multilayer film 92, the number of stacked layers of the low acoustic impedance layers 92a, 92c, 92e and the high acoustic impedance layers 92b, 92d is not particularly limited. As long as at least one high acoustic impedance layer 92b, 92d is disposed on the side farther from the piezoelectric layer 2 than the low acoustic impedance layers 92a, 92c, 92e.

[0353] As long as the above low acoustic impedance layers 92a, 92c, 92e and high acoustic impedance layers 92b, 92d satisfy the above acoustic impedance relationship, they can be made of appropriate materials. For example, as the materials of the low acoustic impedance layers 92a, 92c, 92e, silicon oxide or silicon oxynitride can be cited. In addition, as the materials of the high acoustic impedance layers 92b, 92d, alumina, silicon nitride or metal can be cited.

[0354] Figure 38 It is a partial cutaway perspective view for explaining an elastic wave device using a Lamb wave.

[0355] The elastic wave device 101 has a support substrate 102. A recess open at the upper surface is provided in the support substrate 102. A piezoelectric layer 103 is stacked on the support substrate 102. Thus, the cavity portion 9 is formed. Above the cavity portion 9, an IDT electrode 104 is provided on the piezoelectric layer 103. Reflectors 105, 106 are provided on both sides of the IDT electrode 104 in the elastic wave propagation direction. In Figure 38 the outer peripheral edge of the cavity portion 9 is shown by a dotted line. Here, the IDT electrode 104 has a first bus bar 104a, a second bus bar 104b, a plurality of first electrode fingers 104c, and a plurality of second electrode fingers 104d. The plurality of first electrode fingers 104c are connected to the first bus bar 104a. The plurality of second electrode fingers 104d are connected to the second bus bar 104b. The plurality of first electrode fingers 104c and the plurality of second electrode fingers 104d are interlaced with each other.

[0356] In the elastic wave device 101, by applying an alternating electric field to the IDT electrode 104 on the cavity portion 9, the Lamb wave as a plate wave is excited. Moreover, since the reflectors 105, 106 are provided on both sides, the resonance characteristics based on the above Lamb wave can be obtained.

[0357] Like this, the elastic wave resonator in the present invention can also be an elastic wave resonator using plate waves.

[0358] In the elastic wave devices of the first to thirteenth embodiments and each modification example, for example, a Figure 37 shown acoustic multilayer film 92 can be provided between the support member and the piezoelectric layer as the piezoelectric film. Specifically, the support member and the piezoelectric film can be arranged such that at least a part of the support member and at least a part of the piezoelectric film face each other with the acoustic multilayer film 92 interposed therebetween. In this case, in the acoustic multilayer film 92, as long as a low acoustic impedance layer and a high acoustic impedance layer are alternately laminated. The acoustic multilayer film 92 can also be an acoustic reflection portion in the elastic wave device. In this case, for example, a plurality of acoustic multilayer films 92 can be provided independently. Moreover, the plurality of electrode fingers in the first elastic wave resonator and the plurality of electrode fingers in the second elastic wave resonator can overlap different acoustic multilayer films 92 in a plan view. Or, the plurality of electrode fingers in the first elastic wave resonator and the plurality of electrode fingers in the second elastic wave resonator can overlap the same acoustic multilayer film 92 in a plan view. In addition, when the acoustic multilayer film 92 is provided in the thirteenth embodiment, the plurality of third electrode fingers in the first elastic wave resonator and the plurality of third electrode fingers in the second elastic wave resonator can be buried in the acoustic multilayer film 92.

[0359] In the first to thirteenth embodiments using body waves of the thickness shear mode and the first elastic wave resonator in each modification example, as described above, d / p is preferably 0.5 or less, more preferably 0.24 or less. Thereby, better resonance characteristics can be obtained. The same applies to the second elastic wave resonator in the first to thirteenth embodiments using body waves of the thickness shear mode and each modification example.

[0360] Furthermore, in the excitation region of the first elastic wave resonator in the first to thirteenth embodiments using body waves of the thickness shear mode and each modification example, as described above, it is preferable to satisfy MR≤1.75(d / p)+0.075. More specifically, when the metallization ratios of the first electrode fingers and the third electrode fingers and the second electrode fingers and the third electrode fingers with respect to the excitation region are set as MR, it is preferable to satisfy MR≤1.75(d / p)+0.075. In this case, spurious can be more reliably suppressed. The same applies to the excitation region of the second elastic wave resonator in the first to thirteenth embodiments using body waves of the thickness shear mode and each modification example.

[0361] Description of reference numerals

[0362] 1: Elastic wave device;

[0363] 2: Piezoelectric layer;

[0364] 2a, 2b: First main surface, second main surface;

[0365] 3, 4: Electrodes;

[0366] 5, 6: First bus bar, second bus bar;

[0367] 7: Insulating layer;

[0368] 7a: Through hole;

[0369] 8: Support member;

[0370] 8a: Through hole;

[0371] 9: Cavity portion;

[0372] 10: SAW device;

[0373] 10A, 10B: First SAW resonator, second SAW resonator;

[0374] 10C: First SAW resonator;

[0375] 10a, 10b: Cavity portion;

[0376] 11: Functional electrode;

[0377] 11a, 11b: First surface, second surface;

[0378] 11c: Side surface;

[0379] 12: Piezoelectric substrate;

[0380] 13: Support member;

[0381] 14: Piezoelectric layer;

[0382] 14a, 14b: First main surface, second main surface;

[0383] 15: Insulating layer;

[0384] 16: Support substrate;

[0385] 17, 18: First comb-shaped electrode, second comb-shaped electrode;

[0386] 19, 19A: Third electrode;

[0387] 22 - 24: First bus bar - third bus bar;

[0388] 24A, 24B: First connection electrode, second connection electrode;

[0389] 24C: Connection electrode;

[0390] 24a: Strip portion;

[0391] 24b: Protrusion;

[0392] 25 - 27: First electrode finger - Third electrode finger;

[0393] 28A, 28B: First signal potential wiring, Second signal potential wiring;

[0394] 28C: Reference potential wiring;

[0395] 29A, 29B: Insulating film;

[0396] 31: Functional electrode;

[0397] 31a, 31b: First surface, Second surface;

[0398] 31c: Side surface;

[0399] 32 - 34: Fourth bus bar - Sixth bus bar;

[0400] 35 - 37: Fourth electrode finger - Sixth electrode finger;

[0401] 39: Sixth electrode;

[0402] 40A, 40B: First surface acoustic wave resonator, Second surface acoustic wave resonator;

[0403] 48A, 48B: Dielectric film;

[0404] 50A, 50B: First surface acoustic wave resonator, Second surface acoustic wave resonator;

[0405] 53A - 53D: Reflector;

[0406] 53a, 53b: First reflector bus bar, Second reflector bus bar;

[0407] 53c: Multiple reflector electrode fingers;

[0408] 60: Surface acoustic wave device;

[0409] 70A, 70B: First surface acoustic wave resonator, Second surface acoustic wave resonator;

[0410] 73A, 73D, 73E: First reflector, Second reflector, Third reflector;

[0411] 80A, 80B: First surface acoustic wave resonator, Second surface acoustic wave resonator;

[0412] 90, 91: Surface acoustic wave device;

[0413] 92: Acoustic multilayer film;

[0414] 92a, 92c, 92e: Low acoustic impedance layers;

[0415] 92b, 92d: High acoustic impedance layers;

[0416] 101: Elastic wave device;

[0417] 102: Support substrate;

[0418] 103: Piezoelectric layer;

[0419] 104: IDT electrode;

[0420] 104a, 104b: First bus bar, second bus bar;

[0421] 104c, 104d: First electrode finger, second electrode finger;

[0422] 105, 106: Reflectors;

[0423] 201: Piezoelectric film;

[0424] 201a, 201b: First main surface, second main surface;

[0425] 451, 452: First region, second region;

[0426] C: Excitation region;

[0427] E: Crossing region;

[0428] g1, g2, g4, g5: Gaps;

[0429] R: Region;

[0430] VP1: Imaginary plane.

Claims

1. An elastic wave device, comprising: a first elastic wave resonator; and a second elastic wave resonator, wherein the first elastic wave resonator and the second elastic wave resonator each have a piezoelectric film, a first comb-shaped electrode connected to an input potential, a second comb-shaped electrode connected to an output potential, and a third electrode connected to a reference potential, the piezoelectric film includes a piezoelectric layer, and the piezoelectric layer includes lithium niobate, the first comb-shaped electrode is provided on the piezoelectric layer and has a first bus bar and a plurality of first electrode fingers, and one ends of the plurality of first electrode fingers are respectively connected to the first bus bar, the second comb-shaped electrode is provided on the piezoelectric layer and has a second bus bar and a plurality of second electrode fingers, and one ends of the plurality of second electrode fingers are respectively connected to the second bus bar, and the plurality of second electrode fingers are interlaced with and inserted into the plurality of first electrode fingers, the third electrode has a plurality of third electrode fingers and connection electrodes connecting adjacent third electrode fingers to each other, and the third electrode fingers are respectively provided on the piezoelectric layer so as to be arranged in the direction in which the first electrode fingers and the second electrode fingers are arranged when viewed from above and to be arranged with the first electrode fingers and the second electrode fingers, in each of the first elastic wave resonator and the second elastic wave resonator, when viewed from above, the order in which the first electrode fingers, the second electrode fingers, and the third electrode fingers are arranged is the order in which the first electrode fingers, the third electrode fingers, the second electrode fingers, and the third electrode fingers are taken as one cycle starting from the first electrode fingers, the first elastic wave resonator and the second elastic wave resonator are respectively divided resonators obtained by serially dividing one elastic wave resonator.

2. An elastic wave device, comprising: a first elastic wave resonator; and a second elastic wave resonator, wherein the first elastic wave resonator and the second elastic wave resonator each have a piezoelectric film, a first comb-shaped electrode connected to an input potential, a second comb-shaped electrode connected to an output potential, and a third electrode connected to a reference potential, the piezoelectric film includes a piezoelectric layer, and the piezoelectric layer includes lithium niobate, the first comb-shaped electrode is provided on the piezoelectric layer and has a first bus bar and a plurality of first electrode fingers, and one ends of the plurality of first electrode fingers are respectively connected to the first bus bar, the second comb-shaped electrode is provided on the piezoelectric layer and has a second bus bar and a plurality of second electrode fingers, and one ends of the plurality of second electrode fingers are respectively connected to the second bus bar, and the plurality of second electrode fingers are interlaced with and inserted into the plurality of first electrode fingers, the third electrode has a plurality of third electrode fingers and connection electrodes connecting adjacent third electrode fingers to each other, and the third electrode fingers are respectively provided on the piezoelectric layer so as to be arranged in the direction in which the first electrode fingers and the second electrode fingers are arranged when viewed from above and to be arranged with the first electrode fingers and the second electrode fingers, In each of the first elastic wave resonator and the second elastic wave resonator, when viewed from above, the order in which the first electrode finger, the second electrode finger, and the third electrode finger are arranged is such that, starting from the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger form one cycle. The first elastic wave resonator and the second elastic wave resonator are each a divided resonator obtained by parallel-dividing one elastic wave resonator.

3. The elastic wave device according to claim 2, wherein, in each of the first elastic wave resonator and the second elastic wave resonator, when the direction orthogonal to the direction in which the first electrode finger, the second electrode finger, and the third electrode finger extend is defined as the electrode orthogonal direction, the first elastic wave resonator and the second elastic wave resonator are arranged in the electrode orthogonal direction. The first elastic wave resonator has a first reflector provided on the piezoelectric layer, the second elastic wave resonator has a second reflector provided on the piezoelectric layer, and the first elastic wave resonator and the second elastic wave resonator share a third reflector. The third reflector is provided between the region where the first electrode finger, the second electrode finger, and the third electrode finger of the first elastic wave resonator are provided and the region where the first electrode finger, the second electrode finger, and the third electrode finger of the second elastic wave resonator are provided. The first reflector and the third reflector face each other with the region where the first electrode finger, the second electrode finger, and the third electrode finger of the first elastic wave resonator are provided therebetween, and the second reflector and the third reflector face each other with the region where the first electrode finger, the second electrode finger, and the third electrode finger of the second elastic wave resonator are provided therebetween.

4. The elastic wave device according to claim 1 or 2, wherein, in each of the first elastic wave resonator and the second elastic wave resonator, when the direction orthogonal to the direction in which the first electrode finger, the second electrode finger, and the third electrode finger extend is defined as the electrode orthogonal direction, one of the first elastic wave resonator and the second elastic wave resonator has a pair of reflectors provided on the piezoelectric layer so as to sandwich the region where the first electrode finger, the second electrode finger, and the third electrode finger are provided in the electrode orthogonal direction, and the other of the first elastic wave resonator and the second elastic wave resonator does not have the reflector.

5. The elastic wave device according to any one of claims 1 to 4, wherein, the total number of the first electrode finger, the second electrode finger, and the third electrode finger of the first elastic wave resonator and the total number of the first electrode finger, the second electrode finger, and the third electrode finger of the second elastic wave resonator are different from each other.

6. The elastic wave device according to any one of claims 1 to 5, wherein, When the center-to-center distance between adjacent first electrode fingers and third electrode fingers and the center-to-center distance between adjacent third electrode fingers and second electrode fingers in the first elastic wave resonator are set to p1, and the center-to-center distance between adjacent first electrode fingers and third electrode fingers and the center-to-center distance between adjacent second electrode fingers and third electrode fingers in the second elastic wave resonator are set to p2, p1 ≠ p2.

7. The elastic wave device according to any one of claims 1 to 6, wherein when the widths of the first electrode finger, the second electrode finger, and the third electrode finger in the first elastic wave resonator are set to w1, and the widths of the first electrode finger, the second electrode finger, and the third electrode finger in the second elastic wave resonator are set to w2, w1 ≠ w2.

8. The elastic wave device according to any one of claims 1 to 7, wherein the first elastic wave resonator and the second elastic wave resonator each have a dielectric film provided on the piezoelectric layer to cover the first electrode finger, the second electrode finger, and the third electrode finger, when the thickness of the dielectric film of the first elastic wave resonator is set to td1, and the thickness of the dielectric film of the second elastic wave resonator is set to td2, td1 ≠ td2.

9. The elastic wave device according to any one of claims 1 to 8, wherein when the thicknesses of the first electrode finger, the second electrode finger, and the third electrode finger of the first elastic wave resonator are set to te1, and the thicknesses of the first electrode finger, the second electrode finger, and the third electrode finger of the second elastic wave resonator are set to te2, te1 ≠ te2.

10. The elastic wave device according to any one of claims 1 to 9, wherein in each of the first elastic wave resonator and the second elastic wave resonator, the tips of the plurality of first electrode fingers and the plurality of second electrode fingers face an electrode that is connected to a potential different from that of the electrode fingers and is connected to any one of an input potential, an output potential, and a reference potential with a gap therebetween, when the direction in which the first electrode finger, the second electrode finger, and the third electrode finger extend is set as the electrode finger extension direction, the dimension of the gap along the electrode finger extension direction is set as the gap length, the gap length in the first elastic wave resonator is set to G1, and the gap length in the second elastic wave resonator is set to G2, G1 ≠ G2.

11. The elastic wave device according to any one of claims 1 to 10, wherein in each of the first elastic wave resonator and the second elastic wave resonator, when the direction in which the first electrode finger, the second electrode finger, and the third electrode finger extend is set as the electrode finger extension direction, the overlapping region of the first electrode finger and the second electrode finger when viewed from a direction orthogonal to the electrode finger extension direction is the crossing region, When the dimension of the cross region in the first elastic wave resonator along the extending direction of the electrode fingers is set as the cross width Ap1, and the dimension of the cross region in the second elastic wave resonator along the extending direction of the electrode fingers is set as the cross width Ap2, Ap1 ≠ Ap2.

12. The elastic wave device according to any one of claims 1 to 11, wherein, each of the first elastic wave resonator and the second elastic wave resonator is configured to be able to utilize plate waves.

13. The elastic wave device according to any one of claims 1 to 11, wherein, each of the first elastic wave resonator and the second elastic wave resonator is configured to be able to utilize bulk waves in the thickness shear mode.

14. The elastic wave device according to any one of claims 1 to 11, wherein, each of the first elastic wave resonator and the second elastic wave resonator further has a support member laminated on the piezoelectric film, in each of the first elastic wave resonator and the second elastic wave resonator, when viewed from above in the lamination direction of the support member and the piezoelectric film, an acoustic reflection portion is formed at a position in the support member overlapping with the plurality of first electrode fingers, the plurality of second electrode fingers, and the plurality of third electrode fingers, in each of the first elastic wave resonator and the second elastic wave resonator, when the longest distance among the center-to-center distances between adjacent first electrode fingers and adjacent third electrode fingers and the center-to-center distances between adjacent second electrode fingers and adjacent third electrode fingers is set as p, and the thickness of the piezoelectric film is set as d, d / p is 0.5 or less.

15. The elastic wave device according to claim 14, wherein, in each of the first elastic wave resonator and the second elastic wave resonator, d / p is 0.24 or less.

16. The elastic wave device according to claim 14 or 15, wherein, in each of the first elastic wave resonator and the second elastic wave resonator, the acoustic reflection portion is a cavity portion, and the support member and the piezoelectric film are arranged such that a part of the support member and a part of the piezoelectric film are opposed to each other with the cavity portion therebetween.

17. The elastic wave device according to claim 14 or 15, wherein, in each of the first elastic wave resonator and the second elastic wave resonator, the acoustic reflection portion is an acoustic reflection film including a high acoustic impedance layer with a relatively high acoustic impedance and a low acoustic impedance layer with a relatively low acoustic impedance, and the support member and the piezoelectric film are arranged such that at least a part of the support member and at least a part of the piezoelectric film are opposed to each other with the acoustic reflection film therebetween.

18. The elastic wave device according to any one of claims 14 to 17, wherein, In each of the first elastic wave resonator and the second elastic wave resonator, when the direction orthogonal to the direction in which the first electrode finger, the second electrode finger, and the third electrode finger extend is defined as the electrode finger orthogonal direction, the regions where the adjacent first electrode finger and the third electrode finger overlap each other in the electrode finger orthogonal direction and the regions where the adjacent second electrode finger and the third electrode finger overlap each other in the electrode finger orthogonal direction are excitation regions. In each of the first elastic wave resonator and the second elastic wave resonator, when the metallization ratios of the first electrode finger and the third electrode finger and the second electrode finger and the third electrode finger with respect to the excitation region are set as MR, MR ≤ 1.75(d / p) + 0.075 is satisfied.

19. The elastic wave device according to any one of claims 1 to 18, wherein, in each of the first elastic wave resonator and the second elastic wave resonator, the Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric layer are within the range of the following formula (1), formula (2), or formula (3). (within the range of 0° ± 10°, 0° to 25°, any ψ) … formula (1) In the range of (0° ± 10°), 25° to 100°, 0° to 75° [(1 - (θ - 50) 2 / 2500)] 1 / 2 or 180° - 75° [(1 - (θ - 50) 2 / 2500)] 1 / 2 ~180°) … Equation (2) In the range of (0° ± 10°), 180° - 40°[(1 - (ψ - 90) 2 / 8100)] 1 / 2 ~180°, for any ψ) … formula (3).

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