Acoustic wave device

Abstract

To provide an acoustic wave device capable of suppressing an unwanted wave.SOLUTION: An acoustic wave device 1 used for a filter device comprises: a plurality of elastic wave resonators that include a piezoelectric substrate 2 having a piezoelectric layer 6, and an IDT electrode that is provided thereon, and has a plurality of electrode fingers. A first elastic wave resonator 1A from the plurality of elastic wave resonators is an excitation angle change type resonator. In the excitation angle change type resonator, the piezoelectric layer 6 includes a propagation axis; the plurality of electrode fingers are bent; and an excitation direction of an elastic wave in an arbitrary part is any one of first to third directions of an arbitrary electrode finger from the plurality of electrode fingers. When an angle of a corner formed by the excitation direction and a direction where the propagation axis extends is an excitation angle, the excitation angles are not the same in the IDT electrode. The plurality of elastic wave resonators are serially or parallely connected with each other; the other element is not connected between the plurality of elastic wave resonators; and a circuit of a filter device is not branched between the plurality of elastic wave resonators.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, acoustic wave devices have been widely used in filters of mobile phones and the like. Patent Document 1 below discloses an example of a multiplexer in which a plurality of acoustic wave resonators are used as series resonators and parallel resonators. This multiplexer has two duplexers. Each of the two duplexers has two filters. Each filter is commonly connected to a common terminal.

[0003] A filter has a plurality of series resonators and a plurality of parallel resonators. In the filter, the series resonator closest to the common terminal is composed of a plurality of split resonators divided in series. Each of these split resonators has an IDT (Interdigital Transducer) electrode and a reflector. The split resonators differ from each other in at least one of the electrode finger pitch, the cross width, the number of pairs of electrode fingers, the duty, and the distance between the IDT electrode and the reflector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 003297 Summary of the Invention [Problem to be solved by the invention]

[0005] In the multiplexer described in Patent Document 1, in order to sufficiently suppress spurious waves, it is necessary to split the series resonators in series more. Therefore, the total area of ​​the split resonators tends to be large. On the other hand, if the number of split resonators is small, it is difficult to sufficiently suppress spurious waves.

[0006] An object of the present invention is to provide an acoustic wave device capable of suppressing unwanted waves. [Means for solving the problem]

[0007] An elastic wave device according to the present invention is an elastic wave device used in a filter device, comprising: a piezoelectric substrate having a piezoelectric layer; and a plurality of elastic wave resonators each having an IDT electrode provided on the piezoelectric substrate and having a plurality of electrode fingers, wherein at least one of the plurality of elastic wave resonators is an excitation angle variable resonator, wherein the piezoelectric layer has a propagation axis and the plurality of electrode fingers are curved, and wherein an excitation direction of an elastic wave in an arbitrary portion of any one of the plurality of electrode fingers in the excitation angle variable resonator is any one of first to third directions, and the first direction is a direction in which the electrode fingers extend. the first direction is a direction perpendicular to the excitation direction, the second direction is a direction connecting the electrode finger and the electrode fingers adjacent to the electrode finger at the shortest distance, the third direction is a direction of an electric field vector generated between the electrode finger and the electrode fingers adjacent to the electrode finger at the shortest distance, and in the excitation angle variable resonator, when the angle between the excitation direction and the direction in which the propagation axis extends is defined as an excitation angle, the excitation angle is not uniform in the IDT electrode, the multiple elastic wave resonators are connected to each other in series or in parallel, no other elements are connected between the multiple elastic wave resonators, and a circuit of the filter device does not branch between the multiple elastic wave resonators. Effect of the Invention

[0008] According to an elastic wave device according to a preferred embodiment of the present invention, unwanted waves can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic plan view of an elastic wave device according to a first preferred embodiment of the present invention. [Diagram 2] 1 is a filter device according to an embodiment of the present invention. [Diagram 3]1 is a schematic plan view of a first acoustic wave resonator according to a first embodiment of the present invention. [Figure 4] 4 is a schematic cross-sectional view taken along a two-dot chain line N in FIG. [Diagram 5] 4 is a schematic plan view of a second acoustic wave resonator according to the first embodiment of the present invention. FIG. [Figure 6] 1 is a schematic plan view of an elastic wave device of a comparative example. [Figure 7] FIG. 4 is a diagram showing phase characteristics near a frequency at which spurious waves are generated in the first embodiment of the present invention and a comparative example. [Figure 8] 1 is a schematic plan view of an elastic wave device according to a first modified example of the first embodiment of the present invention. [Figure 9] FIG. 2 is a schematic plan view of a first acoustic wave resonator according to a first modified example of the first embodiment of the present invention. [Figure 10] 11 is a schematic plan view showing a circle including an arc when a shape of an electrode finger in a plan view of a first IDT electrode in a first modified example of the first embodiment of the present invention is approximated to the arc. FIG. [Figure 11] 10 is a schematic plan view of an elastic wave device according to a second modified example of the first embodiment of the present invention. FIG. [Figure 12] 10 is a schematic plan view of a first acoustic wave resonator according to a second modified example of the first embodiment of the present invention. FIG. [Figure 13] FIG. 11 is a schematic plan view showing parallel regions and non-parallel regions in a second modified example of the first embodiment of the present invention. [Figure 14] FIG. 13 is a schematic plan view of a first acoustic wave resonator according to a third modified example of the first embodiment of the present invention. [Figure 15] FIG. 13 is a schematic plan view of a first acoustic wave resonator according to a fourth modified example of the first embodiment of the present invention. [Figure 16] FIG. 13 is a schematic plan view of a first acoustic wave resonator according to a fifth modified example of the first embodiment of the present invention. [Figure 17] FIG. 13 is a schematic plan view showing the vicinity of a first edge region and a second edge region in a sixth modified example of the first embodiment of the present invention. [Figure 18] 10A is a schematic cross-sectional view showing a cross section along the extension direction of a first electrode finger in a seventh modified example of the first embodiment of the present invention, near a first edge region, a second edge region, and a central region of the first electrode finger, and 10B is a schematic cross-sectional view showing a cross section along the extension direction of a second electrode finger in a seventh modified example of the first embodiment of the present invention, near a first edge region, a second edge region, and a central region of the second electrode finger. [Figure 19] FIG. 13 is a schematic plan view of a first acoustic wave resonator according to an eighth modification of the first embodiment of the present invention. [Figure 20] 13 is a schematic plan view of an elastic wave device according to a ninth modification of the first embodiment of the present invention. FIG. [Figure 21] 10 is a schematic plan view of an elastic wave device according to a second preferred embodiment of the present invention. FIG. [Figure 22] 11 is a schematic plan view of an elastic wave device according to a third preferred embodiment of the present invention. FIG. [Figure 23] FIG. 4 is a diagram showing phase characteristics near a frequency at which spurious waves are generated in the first embodiment, the third embodiment, and a comparative example of the present invention. [Figure 24] 13 is a schematic plan view of an elastic wave device according to a first modified example of a third embodiment of the present invention. FIG. [Diagram 25] 13 is a schematic plan view of an elastic wave device according to a second modified example of the third embodiment of the present invention. FIG. [Figure 26] FIG. 11 is a diagram showing phase characteristics near a frequency at which spurious waves are generated in the first embodiment of the present invention, the second modified example of the third embodiment, and a comparative example. [Figure 27] 13 is a schematic plan view of an elastic wave device according to a third modified example of the third embodiment of the present invention. FIG. [Figure 28] 11 is a schematic plan view of an elastic wave device according to a fourth preferred embodiment of the present invention. FIG. [Figure 29] 13 is a schematic plan view of an elastic wave device according to a modified example of the fourth embodiment of the present invention. FIG. [Diagram 30] FIG. 13 is a schematic plan view of an elastic wave device according to a fifth preferred embodiment of the present invention. [Diagram 31] FIG. 11 is a diagram showing phase characteristics near a frequency at which spurious waves are generated in the first embodiment, the fifth embodiment, and a comparative example of the present invention. [Diagram 32] 13 is a schematic plan view of an elastic wave device according to a modified example of the fifth embodiment of the present invention. FIG. [Diagram 33] 13 is a schematic cross-sectional front view of an elastic wave device according to a sixth preferred embodiment of the present invention. [Diagram 34] 23 is a schematic cross-sectional front view of an elastic wave device according to a first modified example of the sixth embodiment of the present invention. FIG. [Diagram 35] 13 is a schematic cross-sectional front view of an elastic wave device according to a second modified example of the sixth embodiment of the present invention. FIG. [Diagram 36] 13 is a schematic cross-sectional front view of an elastic wave device according to a seventh preferred embodiment of the present invention. [Figure 37] 13 is a schematic cross-sectional front view of an elastic wave device according to an eighth preferred embodiment of the present invention. FIG. [Figure 38] 13 is a schematic cross-sectional front view of an elastic wave device according to a first modified example of an eighth embodiment of the present invention. FIG. [Figure 39] 13 is a schematic cross-sectional front view of an elastic wave device according to a second modified example of the eighth embodiment of the present invention. FIG. [Diagram 40] 13 is a schematic cross-sectional front view of an elastic wave device according to a third modified example of the eighth embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be clarified below by describing specific embodiments of the present invention with reference to the drawings.

[0011] It should be noted that each embodiment described in this specification is merely illustrative, and partial substitution or combination of configurations is possible between different embodiments.

[0012] Fig. 1 is a schematic plan view of an acoustic wave device according to a first preferred embodiment of the present invention, in which an IDT electrode and a reflector, which will be described later, are illustrated by shapes including curves or by a rectangle with two diagonal lines added.

[0013] 1 is used as a part of a filter device. The elastic wave device 1 has a plurality of elastic wave resonators. In this embodiment, the plurality of elastic wave resonators are specifically a first elastic wave resonator 1A and a second elastic wave resonator 1B.

[0014] FIG. 2 shows a filter device according to one embodiment of the present invention.

[0015] The filter device 10 is a ladder-type filter. The filter device 10 has a plurality of series arm resonators and a plurality of parallel arm resonators. The first elastic wave resonator 1A and the second elastic wave resonator 1B in the first embodiment are split resonators divided in series. That is, the first elastic wave resonator 1A and the second elastic wave resonator 1B are connected in series with each other, and no other element is connected between the first elastic wave resonator 1A and the second elastic wave resonator 1B. The circuit of the filter device 10 is not branched between the first elastic wave resonator 1A and the second elastic wave resonator 1B.

[0016] The first elastic wave resonator 1A and the second elastic wave resonator 1B may be, for example, split resonators divided in parallel. In the filter device 10, the first elastic wave resonator 1A and the second elastic wave resonator 1B are series arm resonators. However, the first elastic wave resonator 1A and the second elastic wave resonator 1B may be parallel arm resonators divided in series or in parallel.

[0017] The elastic wave resonators of the elastic wave device according to the present invention may be resonators that correspond to split resonators in terms of circuit configuration. For example, the resonant frequencies of the elastic wave resonators do not need to be the same.

[0018] Although details will be described later, first elastic wave resonator 1A in elastic wave device 1 is an excitation angle variable resonator. On the other hand, second elastic wave resonator 1B is an elastic wave resonator that is not an excitation angle variable resonator. Note that an elastic wave device according to the present invention may include at least two elastic wave resonators. It is sufficient that the multiple elastic wave resonators include at least one excitation angle variable resonator. A specific configuration of elastic wave device 1 according to the first preferred embodiment will be described below.

[0019] Fig. 3 is a schematic plan view of a first acoustic wave resonator according to the first preferred embodiment, and Fig. 4 is a schematic cross-sectional view taken along a two-dot chain line N in Fig. 3.

[0020] As shown in FIG. 3 and FIG. 4, the first acoustic wave resonator 1A has a piezoelectric substrate 2. As shown in FIG. 4, the piezoelectric substrate 2 is a laminated substrate including a piezoelectric layer 6. That is, the piezoelectric substrate 2 is a substrate having piezoelectricity. Specifically, the piezoelectric substrate 2 has a support member 3 and a piezoelectric layer 6. More specifically, the support member 3 has a support substrate 4 and an intermediate layer 5. The intermediate layer 5 includes a first layer 5a and a second layer 5b. The first layer 5a is provided on the support substrate 4. The second layer 5b is provided on the first layer 5a. The piezoelectric layer 6 is provided on the second layer 5b. The layer configuration of the piezoelectric substrate 2 is not limited to the above. For example, the intermediate layer 5 may be a single dielectric layer. Alternatively, the piezoelectric substrate 2 may be a substrate consisting of only the piezoelectric layer 6.

[0021] In the first embodiment, silicon is used as the material of the support substrate 4. Silicon nitride is used as the material of the first layer 5a. Silicon oxide is used as the material of the second layer 5b. Rotated Y-cut X-propagation lithium tantalate is used as the material of the piezoelectric layer 6. Thus, the piezoelectric layer 6 has a propagation axis. The direction of the propagation axis is the X-direction. However, the materials of each layer of the piezoelectric substrate 2 are not limited to those mentioned above.

[0022] The piezoelectric layer 6 has a first principal surface 6a and a second principal surface 6b. The first principal surface 6a and the second principal surface 6b face each other. Of the first principal surface 6a and the second principal surface 6b, the second principal surface 6b is located on the support substrate 4 side. A first IDT electrode 18A is provided on the first principal surface 6a of the piezoelectric layer 6. This forms a first acoustic wave resonator 1A.

[0023] As shown in Fig. 3, first IDT electrode 18A has a pair of bus bars and a plurality of electrode fingers. The pair of bus bars is specifically first bus bar 14A and second bus bar 15A. First bus bar 14A and second bus bar 15A face each other. The plurality of electrode fingers is specifically a plurality of first electrode fingers 16A and a plurality of second electrode fingers 17A. One ends of the plurality of first electrode fingers 16A are connected to first bus bar 14A. One ends of the plurality of second electrode fingers 17A are connected to second bus bar 15A.

[0024] Each of the first electrode fingers 16A and the second electrode fingers 17A includes a base end, a tip end, and a pair of edge portions. Specifically, the base end of the first electrode finger 16A is a portion connected to the first bus bar 14A. The pair of edge portions of the first electrode finger 16A are portions connecting the base end and the tip end. The base end of the second electrode finger 17A is a portion connected to the second bus bar 15A. The pair of edge portions of the second electrode finger 17A are portions connecting the base end and the tip end in a plan view. The first electrode fingers 16A and the second electrode fingers 17A are interdigitated with each other. In this specification, a plan view refers to a view from a direction corresponding to the top in FIG. 4. In FIG. 4, for example, the piezoelectric layer 6 side is the top of the supporting substrate 4 side and the piezoelectric layer 6 side.

[0025] The tip portions of the first electrode fingers 16A and the second electrode fingers 17A each include a tip. An imaginary line formed by connecting the tips of the second electrode fingers 17A is a first envelope E1. Similarly, an imaginary line formed by connecting the tips of the first electrode fingers 16A is a second envelope E2. Note that, hereinafter, the first electrode fingers 16A and the second electrode fingers 17A may be simply referred to as electrode fingers. The first bus bar 14A and the second bus bar 15A may be simply referred to as bus bars.

[0026] The region between the first envelope E1 and the second envelope E2 is the intersection region J. More specifically, the region surrounded by an edge of an electrode finger at one end in the direction in which the electrode fingers are arranged, an edge of an electrode finger at the other end, the first envelope E1, and the second envelope E2 is the intersection region J. Thus, the first envelope E1 corresponds to the edge of the intersection region J on the first bus bar 14A side. The second envelope E2 corresponds to the edge of the intersection region J on the second bus bar 15A side. In the intersection region J, adjacent electrode fingers overlap each other when viewed from the direction in which the first envelope E1 or the second envelope E2 extends.

[0027] In the first embodiment, the intersection region J is formed of one curved region. The curved region is a region in which the shapes of the first electrode fingers 16A and the second electrode fingers 17A are each curved in a plan view. One edge of the curved region forming the intersection region J is a first envelope curve E1. The other edge is a second envelope curve E2. However, in the first acoustic wave resonator 1A which is an excitation angle variable resonator, it is sufficient that the electrode fingers are curved. For example, the shape of the electrode fingers in a plan view may be bent at multiple nodes.

[0028] By applying an AC voltage to the first IDT electrode 18A, an acoustic wave is excited in the intersection region J. More specifically, for example, the SH mode is excited as the main mode. In this case, the Rayleigh wave becomes an unwanted wave. However, the main mode is not limited to the SH mode.

[0029] As described above, the intersection region J of the first IDT electrode 18A is a curved region. In the curved region, the shape of each electrode finger is curved in a plan view. Therefore, in the curved region of the first IDT electrode 18A, the excitation direction of the acoustic wave is not uniform.

[0030] 3, the shape of the first electrode fingers 16A and the second electrode fingers 17A of the first IDT electrode 18A in a plan view is an arc shape. Specifically, the shape of the electrode fingers in a plan view corresponds to each of the arcs in the concentric circles. Therefore, the centers of the circles including the arcs in the shapes of the electrode fingers are coincident. The center is defined as a fixed point C.

[0031] The shape of the electrode fingers of first IDT electrode 18A is not limited to the above. When intersection region J includes a curved region, the shape of the electrode fingers of first IDT electrode 18A in a plan view may be a curved shape in the curved region. The shape of the electrode fingers of first IDT electrode 18A in a plan view may be, for example, an elliptical arc shape, or a curved shape other than a circular arc or an elliptical arc. Alternatively, intersection region J may not include a curved region, and the shape of the electrode fingers in a plan view may be a shape bent at multiple nodes.

[0032] In the first embodiment, the outward direction is the direction in which the curved portion of the electrode finger is convex in the direction in which the electrode fingers are arranged. Specifically, the rightward direction in FIG. 3 is the outward direction of the first acoustic wave resonator 1A. The direction opposite to the outward direction is the inward direction. More specifically, the inward direction is the direction in which the curved portion of the electrode finger is concave in the direction in which the electrode fingers are arranged. The leftward direction in FIG. 3 is the inward direction of the first acoustic wave resonator 1A. The same applies to the case in which the shape of the electrode fingers in a plan view is bent at multiple nodes. The outward direction is the direction in which the curved portion of the electrode finger is convex in the direction in which the electrode fingers are arranged.

[0033] When the ellipse coefficient of a circle or ellipse including arcs in the shape of the multiple electrode fingers is α2 / α1, the ellipse coefficient α2 / α1 in the first embodiment is 1. α1 corresponds to the dimension of one of the major and minor axes of the ellipse along the axis direction that passes through the intersection region J. α2 corresponds to the dimension of one of the major and minor axes of the ellipse along the axis direction that does not pass through the intersection region J.

[0034] As described above, the piezoelectric layer 6 has a propagation axis. The direction in which the propagation axis extends is parallel to the direction in which the two-dot chain line N in FIG. 3 extends. The first envelope E1 is linear and inclined with respect to the propagation axis. Similarly, the second envelope E2 is linear and inclined with respect to the propagation axis. The direction in which the first envelope E1 extends and the direction in which the second envelope E2 extends intersect. The first envelope E1 and the second envelope E2 are arranged symmetrically with respect to the axis of symmetry passing through the center of the intersection region J. In the first embodiment, the axis of symmetry is parallel to the direction in which the propagation axis extends.

[0035] The shapes and arrangements of the first envelope E1 and the second envelope E2 are not limited to those described above. In the present invention, at least one of the first envelope E1 and the second envelope E2 may be other than linear, or at least one of them may be linear.

[0036] FIG. 5 is a schematic plan view of the second acoustic wave resonator according to the first preferred embodiment.

[0037] The second acoustic wave resonator 1B shares the piezoelectric substrate 2 with the first acoustic wave resonator 1A. The second acoustic wave resonator 1B is an acoustic wave resonator that is not an excitation angle variable resonator. Therefore, in the first embodiment, the piezoelectric layer 6 has a propagation axis in both the first acoustic wave resonator 1A that is an excitation angle variable resonator and the second acoustic wave resonator 1B that is not an excitation angle variable resonator. The second acoustic wave resonator 1B has a second IDT electrode 18B. The second IDT electrode 18B is provided on a first main surface 6a of the piezoelectric layer 6 of the piezoelectric substrate 2.

[0038] Second IDT electrode 18B has a pair of bus bars and a plurality of electrode fingers. The plurality of electrode fingers of second IDT electrode 18B are specifically a plurality of third electrode fingers 16B and a plurality of fourth electrode fingers 17B. The shapes of the plurality of third electrode fingers 16B and the plurality of fourth electrode fingers 17B are linear in a plan view.

[0039] Each of the third electrode fingers 16B and the fourth electrode fingers 17B includes a base end, a tip end, and a pair of edge portions, similar to each electrode finger of the first IDT electrode 18A. The base ends of the third electrode fingers 16B are connected to one bus bar, and the base ends of the fourth electrode fingers 17B are connected to the other bus bar. The third electrode fingers 16B and the fourth electrode fingers 17B are interdigitated with each other.

[0040] An imaginary line formed by connecting the tips of the multiple fourth electrode fingers 17B is defined as a third envelope E3. Similarly, an imaginary line formed by connecting the tips of the multiple third electrode fingers 16B is defined as a fourth envelope E4. The second IDT electrode 18B has an intersection region. The intersection region is a region between the third envelope E3 and the fourth envelope E4. In the intersection region, adjacent electrode fingers overlap each other when viewed from the direction in which the third envelope E3 or the fourth envelope E4 extends.

[0041] The third envelope E3 and the fourth envelope E4 are linear. The third envelope E3 and the fourth envelope E4 extend parallel to the direction in which the propagation axis of the piezoelectric layer 6 extends. The second IDT electrode 18B is a so-called normal type IDT electrode.

[0042] The first embodiment is characterized by the following configuration: 1) The multiple elastic wave resonators include an excitation angle variable resonator. 2) The multiple elastic wave resonators are connected to each other in series or in parallel, no other elements are connected between the multiple elastic wave resonators, and the circuit of the filter device does not branch between the multiple elastic wave resonators. As described above, the elastic wave device 1 of the first embodiment is used in a filter device. In the circuit configuration of the filter device, the multiple elastic wave resonators correspond to split resonators in which one resonator is split in series. This split resonator includes an excitation angle variable resonator. This makes it possible to suppress unwanted waves. Details of this will be described below together with details of the configuration of the first embodiment and details of the excitation angle and the excitation angle variable resonator.

[0043] In the intersection region J shown in FIG. 3, the excitation direction of an acoustic wave in any part of any electrode finger among the multiple first electrode fingers 16A and the multiple second electrode fingers 17A is any one of the following first to third directions. The first direction is a direction perpendicular to the direction in which the electrode finger extends. The second direction is a direction connecting the electrode finger and the adjacent first electrode finger 16A or second electrode finger 17A. The third direction is a direction of an electric field vector generated between the electrode finger and the adjacent first electrode finger 16A or second electrode finger 17A.

[0044] Since each electrode finger in the intersection region J has a curved shape, the direction in which each electrode finger extends varies from position to position. In this specification, unless otherwise specified, the directions in which the curved electrode fingers extend are as follows:

[0045] First, a pair of edge portions of each electrode finger has a curved shape. If an imaginary line is drawn parallel to the direction in which the propagation axis extends so as to connect both edge portions at any part of the electrode finger, the center of gravity of the part located on the imaginary line is defined as the representative point of the imaginary line. An infinite number of imaginary lines can be drawn on the electrode finger, and therefore there are an infinite number of representative points. The direction in which the tangent to the curve connecting these representative points extends is defined as the extension direction of the electrode finger.

[0046] The angle between the excitation direction of the elastic wave and the direction in which the propagation axis of the piezoelectric layer 6 extends is called the excitation angle θ C_prop In the present invention, the excitation angle variable resonator is a resonator in which the excitation angle θ C_prop In other words, in the crossing region J of the excitation angle variable resonator, the excitation angle θ C_prop However, this is not uniform.

[0047] In the first embodiment, the direction in which the propagation axis extends is parallel to the direction in which the two-dot chain line N in FIG. 3 extends. The two-dot chain line N is a straight line passing through the fixed point C and the intersection region J. The fixed point C is defined by the shape of the multiple electrode fingers in a planar view. Specifically, in the first embodiment, the centers of the circles including the arcs in the shapes of the multiple electrode fingers coincide with each other. This center is the fixed point C. In the portion indicated by the two-dot chain line N, the excitation angle θ C_prop is 0°. Excitation angle θ C_prop The parts where the angle is 0° are lined up in a straight line.

[0048] Similarly, as shown by the straight line M in FIG. 3, in the first embodiment, the excitation angle θ C_prop is other than 0° and the excitation angle θ C_prop The line M also passes through the fixed point C and the intersection region J.

[0049] 3 is an example of a straight line passing through the fixed point C and the intersection region J. That is, the portion of the intersection region J that is located on the straight line M is aligned with the excitation angle θ C_prop is other than 0° and the excitation angle θ C_prop is an example of a portion where the excitation angle θ is the same as that of the portion on the line M. There are an infinite number of straight lines passing through the fixed point C and the intersection region J. In addition, in the portion located on the infinite straight lines (not shown) in the intersection region J, the excitation angle θ is the same as that of the portion located on the line M. C_prop is other than 0° and the excitation angle θ C_prop However, the excitation angle θ C_propIn this way, the shapes of the first electrode fingers 16A and the second electrode fingers 17A in a plan view are different from each other in terms of the excitation angle θ C_prop is other than 0° and the parts that are the same are arranged in a straight line.

[0050] In this specification, the excitation angle θ C_prop The positive direction is the counterclockwise direction in a plan view. More specifically, the direction from second bus bar 15A to first bus bar 14A is the positive direction.

[0051] In the first embodiment, when a straight line passing through the center of the intersection region J is taken as a reference line, the two-dot chain line N coincides with the reference line. Note that the reference line does not necessarily have to extend parallel to the direction in which the propagation axis extends. The angle between the reference line and a straight line passing through the first envelope E1 and the fixed point C is defined as the intersection angle θ. C1_AP The angle between the line passing through the second envelope E2 and the fixed point C and the reference line is called the intersection angle θ C2_AP In this case, θ C_AP2 ≦θ C_prop ≦θ C_AP1 In the first embodiment, the intersection angle θ C_AP1 and intersection angle θ C_AP2 The absolute value of is the same. Therefore, the excitation angle θ C_prop The absolute value of is 0°≦|θ C_prop |≦|θ C_AP1 |=|θ C_AP2 |is.

[0052] In the first IDT electrode 18A of the first embodiment, the excitation angle θ C_prop In the portion where the electrode finger pitch and duty ratio are the same, the electrode finger pitch and duty ratio are constant. Note that the electrode finger pitch is the center-to-center distance between adjacent first electrode fingers 16A and second electrode fingers 17A. When the wavelength defined by the electrode finger pitch of first IDT electrode 18A is λ and the electrode finger pitch is p, λ=2p.

[0053] In the first IDT electrode 18A of the first acoustic wave resonator 1A, the duty ratio is C_propSpecifically, the duty ratio changes according to the excitation angle θ C_prop is the maximum value in the part where the excitation angle |θ C_prop The larger the |, the smaller the value. However, this is not limited to this.

[0054] As shown in FIG. 3, the first IDT electrode 18A has a plurality of offset electrodes. The plurality of offset electrodes of the first IDT electrode 18A are specifically a plurality of first offset electrodes 12A and a plurality of second offset electrodes 13A. One ends of the plurality of first offset electrodes 12A are connected to a first bus bar 14A, respectively. The first electrode fingers 16A and the first offset electrodes 12A are arranged alternately. One ends of the plurality of second offset electrodes 13A are connected to a second bus bar 15A, respectively. The second electrode fingers 17A and the second offset electrodes 13A are arranged alternately.

[0055] Like the first electrode fingers 16A and the second electrode fingers 17A, the first offset electrodes 12A and the second offset electrodes 13A each include a base end and a tip end. The base ends of the first electrode fingers 16A and the first offset electrodes 12A are connected to the first bus bar 14A. The base ends of the second electrode fingers 17A and the second offset electrodes 13A are connected to the second bus bar 15A. The tip end of the first electrode finger 16A and the tip end of the second offset electrode 13A face each other across a gap. The tip end of the second electrode finger 17A and the tip end of the first offset electrode 12A face each other across a gap.

[0056] Hereinafter, the first offset electrode 12A and the second offset electrode 13A may be simply referred to as offset electrodes. The shape of each of the offset electrodes in a plan view includes a curved portion. Note that the first offset electrodes 12A and the second offset electrodes 13A are not necessarily provided.

[0057] A pair of reflectors 9A and 9B are provided on the piezoelectric layer 6. The reflectors 9A and 9B face each other across the first IDT electrode 18A in the direction in which the electrode fingers of the first IDT electrode 18A are arranged.

[0058] The reflector 9A has a pair of reflector bus bars 9a and 9b. The reflector bus bars 9a and 9b face each other. The reflector 9A has a plurality of reflector electrode fingers 9c. One ends of the plurality of reflector electrode fingers 9c are connected to the reflector bus bar 9a. The other ends of the plurality of reflector electrode fingers 9c are connected to the reflector bus bar 9b. The shape of each of the plurality of reflector electrode fingers 9c of the reflector 9A in a plan view includes a curved shape.

[0059] Similarly, the reflector 9B has a pair of reflector bus bars 9d and 9e and a plurality of reflector electrode fingers 9f. The first IDT electrode 18A, the reflector 9A, and the reflector 9B are made of a single-layer metal film. Specifically, in the first embodiment, the first IDT electrode 18A, the reflector 9A, and the reflector 9B are made of Al. Note that the materials of the first IDT electrode 18A, the reflector 9A, and the reflector 9B are not limited to the above. Alternatively, the first IDT electrode 18A, the reflector 9A, and the reflector 9B may be made of a laminated metal film.

[0060] 5, the second IDT electrode 18B of the second acoustic wave resonator 1B also has a plurality of offset electrodes. Specifically, the plurality of offset electrodes of the second IDT electrode 18B are a plurality of third offset electrodes 12B and a plurality of fourth offset electrodes 13B. The plurality of third offset electrodes 12B and the plurality of fourth offset electrodes 13B have linear shapes in a plan view.

[0061] Second acoustic wave resonator 1B has a pair of reflectors, ie, reflector 9C and reflector 9D. Each reflector electrode finger of each reflector has a linear shape in a plan view.

[0062] In the piezoelectric layer 6 of the elastic wave device 1, the direction in which the propagation axis extends is the X-propagation direction. However, this is not limited to this direction. The direction in which the propagation axis extends may be, for example, the 90° X-propagation direction, or may be a direction perpendicular to any of the directions in which the electrode fingers of the first IDT electrode 18A extend.

[0063] As shown in FIG. 4, a dielectric film 8 is provided on the piezoelectric layer 6 so as to cover the first IDT electrode 18A. Since the first IDT electrode 18A is protected by the dielectric film 8, the first IDT electrode 18A is less likely to be damaged. Although not shown, the second IDT electrode 18B is also covered with the dielectric film 8. In the first embodiment, silicon oxide is provided as the material of the dielectric film 8. Note that the material of the dielectric film 8 is not limited to the above. In the first embodiment, the thickness of the dielectric film 8 is constant. Note that the dielectric film 8 is not necessarily provided.

[0064] As described above, when the multiple elastic wave resonators of the elastic wave device 1 include an excitation angle variable resonator, it is possible to suppress unwanted waves. This will be demonstrated below by comparing the first preferred embodiment with a comparative example.

[0065] The comparative example differs from the first embodiment in that both first elastic wave resonator 101A and second elastic wave resonator 101B are so-called normal type elastic wave resonators, as shown in Fig. 6. In other words, the elastic wave resonators of the comparative example do not include an excitation angle variable resonator. The phase characteristics were compared between the elastic wave device having the configuration of the first embodiment and the elastic wave device of the comparative example.

[0066] The design parameters of an elastic wave resonator having the configuration of first elastic wave resonator 1A, which is an excitation angle variable resonator, are as follows. Here, the dimension of the offset electrode along a direction connecting the base end and the tip end is defined as the length of the offset electrode. The dimension of the gap between the tip end of the electrode finger and the tip end of the offset electrode along a direction in which the electrode finger and the offset electrode face each other is defined as the gap length. In the first embodiment, the gap between the tip end of second electrode finger 17A and the tip end of first offset electrode 12A and the gap between the tip end of first electrode finger 16A and the tip end of second offset electrode 13A have the same gap length.

[0067] Support substrate 4: Material: Si, surface orientation: (111), Euler angles (φ, θ, ψ) ψ: 73° First layer 5a of intermediate layer 5: Material: SiN, thickness: 0.15λ Second layer 5b of intermediate layer 5: Material: SiO2, thickness: 0.15λ Piezoelectric layer 6: Material: Rotated Y-cut 55°X-propagation LiTaO3, thickness: 0.2λ First IDT electrode 18A: Material: Al, thickness: 0.05λ Dielectric film 8: Material: SiO2, thickness: 0.015λ Crossing angle θ C1_AP :5° Crossing angle θ C2_AP : -5° Wavelength λ: Excitation angle θ C_prop 2μm at 0° Number of pairs of electrode fingers of the first IDT electrode 18A: 80 pairs Duty ratio: excitation angle θ C_prop is 0.5 at 0°, and the absolute value of the excitation angle |θ C_prop The larger |, the smaller. Gap length: 0.135λ Offset electrode length: 3.5λ Reflector 9A and reflector 9B: Number of pairs of reflector electrode fingers...20 pairs

[0068] In the acoustic wave resonator having the configuration of second acoustic wave resonator 1B, the duty ratio is constant at 0.5. In each of the acoustic wave resonators of the comparative examples, the duty ratio is also constant at 0.5.

[0069] FIG. 7 is a diagram showing phase characteristics in the vicinity of a frequency at which an unwanted wave occurs in the first embodiment and a comparative example.

[0070] As shown in Fig. 7, it can be seen that the first embodiment is able to suppress Rayleigh waves as unwanted waves more effectively than the comparative example. In this way, when the elastic wave devices of the first embodiment and the comparative example have the same number of elastic wave resonators, the first embodiment is able to suppress unwanted waves more effectively than the comparative example. Therefore, in the first embodiment, it is not necessary to increase the number of elastic wave resonators in order to suppress unwanted waves. Therefore, in the first embodiment, unwanted waves can be suppressed without increasing the size of the filter device used.

[0071] When the multiple elastic wave resonators in elastic wave device 1 include first elastic wave resonator 1A as an excitation angle variable resonator, it is possible to suppress unwanted waves in elastic wave device 1. This is for the following reason.

[0072] In the crossing region J of the first acoustic wave resonator 1A shown in FIG. 3, the excitation angle θ C_prop is other than 0° and the excitation angle θ C_prop In the direction in which first bus bar 14A and second bus bar 15A face each other, an infinite number of straight line portions having the same excitation angle θ C_prop are different. Excitation angle θ C_prop In the portions where the frequencies are different from each other, the propagation characteristics of the unwanted waves are different from each other. This makes it possible to disperse the unwanted waves and effectively suppress the unwanted waves. In particular, it is possible to suppress unwanted waves outside the band, such as Rayleigh waves. In this specification, "outside the band" in the elastic wave device refers to the lower frequency side than the resonant frequency and the higher frequency side than the anti-resonant frequency.

[0073] In the first acoustic wave resonator 1A, the first envelope E1 and the second envelope E2 extend at an angle to the propagation axis of the piezoelectric layer 6. This makes it possible to suppress the transverse mode. The transverse mode is an unwanted wave that occurs between the resonant frequency and the anti-resonant frequency. However, the first envelope E1 and the second envelope E2 may extend parallel to the direction in which the propagation axis extends.

[0074] In the first preferred embodiment, an example has been described in which the second acoustic wave resonator 1B is an acoustic wave resonator that is not an excitation angle variable resonator. In the first preferred embodiment, the number of excitation angle variable resonators is one. However, the acoustic wave device 1 may have two or more excitation angle variable resonators. All of the acoustic wave resonators in the acoustic wave device 1 may be excitation angle variable resonators.

[0075] The relationship between an acoustic wave device according to a preferred embodiment of the present invention and a filter device in which the acoustic wave device is used will be described in detail below with reference to FIG.

[0076] As shown in FIG. 2, the filter device 10 is a ladder type filter.

[0077] The filter device 10 has an input terminal 7A and an output terminal 7B, a plurality of series arm resonators, and a plurality of parallel arm resonators. The circuit configuration of the filter device 10 includes a series arm S, a plurality of parallel arms P, and a plurality of nodes D. The series arm S is a path connecting the input terminal 7A and the output terminal 7B. Each series arm resonator is provided in the series arm S. Meanwhile, each parallel arm P is a path branching from the series arm S to each ground terminal. Each parallel arm P is provided with a parallel arm resonator. Meanwhile, the node D is a connection point between the series arm S and the parallel arm P.

[0078] The filter device 10 has a plurality of series arm resonator units. The series arm resonator unit is one series arm resonator or a group of a plurality of series arm resonators connected in series or in parallel to each other without the node D. More specifically, the series arm resonator unit is a portion in which one or more series arm resonators are provided between the input terminal 7A and the node D, between the nodes D, or between the node D and the output terminal 7B.

[0079] In the example shown in FIG. 2, the elastic wave device 1 of the first preferred embodiment is a series arm resonator unit. A first elastic wave resonator 1A and a second elastic wave resonator 1B are two series arm resonators in one series arm resonator unit. The series arm resonator unit is composed of only one or more series arm resonators. Therefore, no other elements are arranged between the multiple elastic wave resonators of the elastic wave device 1. No node D or other branch points are arranged between the multiple series arm resonators in one series arm resonator unit. Therefore, the circuit of the filter device 10 is not branched between the multiple elastic wave resonators of the elastic wave device 1.

[0080] The filter device 10 includes a plurality of series arm resonator units other than the elastic wave device 1. These series arm resonator units are specifically the series arm resonator unit S2 and the series arm resonator unit S3. The elastic wave device 1, the series arm resonator unit S2, and the series arm resonator unit S3 are connected in series with each other in this order from the input terminal 7A side. Each of the series arm resonator unit S2 and the series arm resonator unit S3 is composed of one series arm resonator.

[0081] In filter device 10, the elastic wave device 1 is the series arm resonator unit located closest to input terminal 7A. However, the arrangement of the elastic wave device 1 in filter device 10 is not limited to the above. For example, the elastic wave device 1 may be the series arm resonator unit located closest to output terminal 7B in filter device 10, or may be a series arm resonator unit located neither closest to input terminal 7A nor closest to output terminal 7B.

[0082] The filter device 10 has a plurality of parallel arm resonator units. The parallel arm resonator unit is one parallel arm resonator or a group of a plurality of parallel arm resonators connected in series or parallel to each other in the parallel arm P. The parallel arm resonator unit may be, for example, a portion made up of a plurality of split-type parallel arm resonators. Hereinafter, the series arm resonator unit and the parallel arm resonator unit may be collectively referred to simply as a resonator unit.

[0083] Specifically, the multiple parallel arm resonator sections of the filter device 10 are the parallel arm resonator section P1 and the parallel arm resonator section P2. All of the parallel arm resonator sections of the filter device 10 are composed of one parallel arm resonator. The parallel arm resonator section P1 is connected between a node D between the elastic wave device 1 and the series arm resonator section S2 and the ground potential. The parallel arm resonator section P2 is connected between a node D between the series arm resonator section S2 and the series arm resonator section S3 and the ground potential.

[0084] The elastic wave device 1 may be a parallel arm resonator section corresponding to the parallel arm resonator section P1. In this case, the first elastic wave resonator 1A and the second elastic wave resonator 1B are two parallel arm resonators in one parallel arm resonator section. The parallel arm resonator section is composed of only one or more parallel arm resonators. Therefore, no other elements are arranged between the multiple elastic wave resonators of the elastic wave device 1. No node D or other branch points are arranged between the multiple parallel arm resonators in one parallel arm resonator section. Therefore, even when the elastic wave device 1 corresponds to the parallel arm resonator section P1, the circuit of the filter device 10 does not branch between the multiple elastic wave resonators.

[0085] That is, an elastic wave device according to the present invention is a resonator portion in a filter device. The elastic wave device serving as the resonator portion includes a plurality of elastic wave resonators, and the plurality of elastic wave resonators include at least one excitation angle variable resonator. In the elastic wave device, the plurality of elastic wave resonators may be connected in series to each other or in parallel to each other.

[0086] In the first preferred embodiment, the resonant frequencies of the main modes of the first acoustic wave resonator 1A are substantially equal to each other throughout the entire crossing region J. Specifically, in the first acoustic wave resonator 1A, the duty ratio is C_prop This allows the resonance frequency to be approximately the same in the entire intersection region J.

[0087] Excitation angle θ of the excitation angle variable resonator C_prop In the portions where the resonance frequencies of the main mode and the unwanted waves are different from each other, the relationships between the resonance frequencies of the main mode and the unwanted waves and between the anti-resonance frequencies are different from each other. In the first elastic wave resonator 1A, which is an excitation angle changing resonator, the resonance frequencies of the main mode are the same in the entire crossing region J. Therefore, the frequencies of the unwanted waves are different from each other. This disperses the unwanted waves outside the band. Therefore, the unwanted waves outside the band, such as Rayleigh waves, can be further suppressed.

[0088] In addition, since the resonant frequencies in the crossing region J are substantially the same, the main mode is preferably excited, so that the resonance characteristics can be more reliably improved, and the filter characteristics of the filter device used can be more reliably improved.

[0089] Similarly, even when the anti-resonant frequencies of the main modes in the excitation angle variable resonator are substantially the same throughout the entire crossing region J, the unwanted waves outside the band can be dispersed and further suppressed. In addition, the resonance characteristics of the excitation angle variable resonator can be more reliably improved.

[0090] In this specification, the expression "one frequency and the other frequency are substantially the same" means that the absolute value of the difference between the two frequencies is 2% or less with respect to the reference frequency. C_prop This refers to the frequency when is 0°.

[0091] In the crossing region J of the excitation angle variable resonator, it is preferable that the absolute value of the difference between the highest resonance frequency and the lowest resonance frequency of the main mode is 1% or less with respect to the reference frequency. Alternatively, it is preferable that the absolute value of the difference between the highest anti-resonance frequency and the lowest anti-resonance frequency of the main mode is 1% or less with respect to the reference frequency in the crossing region J of the excitation angle variable resonator. This makes it possible to more reliably improve the resonance characteristics.

[0092] In the first embodiment, the resonant frequencies are substantially the same in the crossing region J of the first elastic wave resonator 1A, which is an excitation angle variable resonator. The first elastic wave resonator 1A and the second elastic wave resonator 1B are split resonators divided in series. In this specification, a plurality of split resonators divided in series refers to a plurality of elastic wave resonators of the same resonator part, which are connected in series with each other, and whose difference in resonant frequencies is 2% or less. On the other hand, in this specification, a plurality of split resonators divided in parallel refers to a plurality of elastic wave resonators of the same resonator part, which are connected in parallel with each other, and whose difference in resonant frequencies is 2% or less.

[0093] More specifically, when comparing the resonance frequency of the excitation angle variable resonator with the resonance frequency of another elastic wave resonator, the excitation angle θ C_prop The resonant frequency of the portion where the excitation angle θ in the crossing region J of the excitation angle variable resonator is compared with the resonant frequency of the other elastic wave resonators. C_prop The resonance frequency at which the angle is 0° is defined as the reference resonance frequency.

[0094] For example, in the first embodiment, the reference resonance frequency of the first elastic wave resonator 1A, which is an excitation angle variable resonator, is compared with the resonance frequency of the second elastic wave resonator 1B, which is an elastic wave resonator that is not an excitation angle variable resonator. The difference between the reference resonance frequency of the first elastic wave resonator 1A and the resonance frequency of the second elastic wave resonator 1B is 2% or less for both the reference resonance frequency and the resonance frequency. Therefore, the first elastic wave resonator 1A and the second elastic wave resonator 1B are split resonators.

[0095] In the present invention, it is sufficient that at least one of the multiple elastic wave resonators in the elastic wave device is an excitation angle variable resonator. The following describes configurations that are preferably established in at least one excitation angle variable resonator in the present invention. Note that in the following description of the excitation angle variable resonator, the reference symbols of the configuration of the first elastic wave resonator 1A may be used.

[0096] It is preferable that the resonant frequencies or anti-resonant frequencies of the main mode in at least one excitation angle changing resonator are substantially the same in the entire crossing region J. This allows for dispersion of unwanted waves outside the band, and further suppression of the unwanted waves outside the band. In addition, since the resonant frequencies or anti-resonant frequencies in the crossing region J are substantially the same, the main mode is preferably excited. This makes it possible to more reliably improve the resonance characteristics. This makes it possible to more reliably improve the filter characteristics of the filter device used.

[0097] At least two of the multiple elastic wave resonators are preferably excitation angle variable resonators, and these elastic wave resonators are preferably split resonators divided in series or parallel. Specifically, in this case, the resonance frequencies of the at least two excitation angle variable resonators are approximately the same in the crossing region J. The following relationship is established between the at least two excitation angle variable resonators. This relationship is such that the difference between the reference resonance frequencies of the two excitation angle variable resonators whose resonance frequencies are approximately the same in the crossing region J is 2% or less with respect to the reference resonance frequencies of both of the two excitation angle variable resonators.

[0098] As a result, the elastic wave resonators having the desired resonant frequency or anti-resonant frequency are divided in series or parallel, so that the applied power can be dispersed, and the elastic wave resonators having the desired resonant frequency or anti-resonant frequency are less likely to be damaged.

[0099] However, the multiple elastic wave resonators of the elastic wave device according to the present invention may be resonators corresponding to the arrangement of split resonators in terms of the circuit configuration. For example, the following relationship may be established between at least two excitation angle variable resonators. This relationship is such that the difference in reference resonance frequency between two excitation angle variable resonators whose resonance frequencies are approximately the same in the crossing region J is greater than 2% with respect to the reference resonance frequency of each of the excitation angle variable resonators.

[0100] It is preferable that at least one of the elastic wave resonators is not an excitation angle variable resonator, but at least one of the elastic wave resonators is an excitation angle variable resonator, and these elastic wave resonators are split resonators divided in series or parallel. Specifically, in this case, the resonance frequencies of at least one excitation angle variable resonator are approximately the same in a crossing region J. The following relationship is established between at least one excitation angle variable resonator and at least one elastic wave resonator that is not an excitation angle variable resonator. This relationship is such that the difference between the reference resonance frequency of the excitation angle variable resonator whose resonance frequencies are approximately the same in the crossing region J and the resonance frequency of the elastic wave resonator that is not an excitation angle variable resonator is 2% or less for both the reference resonance frequency and the resonance frequency.

[0101] Even in this case, since the elastic wave resonators having the desired resonant frequency or anti-resonant frequency are divided in series or parallel, the applied power can be dispersed, and therefore the elastic wave resonators having the desired resonant frequency or anti-resonant frequency are less likely to be damaged.

[0102] On the other hand, the following relationship may be satisfied in at least one excitation angle variable resonator and at least one elastic wave resonator that is not an excitation angle variable resonator, where the difference between the reference resonance frequency of the excitation angle variable resonator, the resonance frequencies of which are substantially the same in the crossing region J, and the resonance frequency of the elastic wave resonator that is not an excitation angle variable resonator is greater than 2% with respect to both the reference resonance frequency and the resonance frequency.

[0103] In the first embodiment, in the first acoustic wave resonator 1A, the duty ratio is set to an excitation angle θ C_prop This causes the resonance frequency to be approximately the same in the entire intersection region J. However, the present invention is not limited to this.

[0104] For example, in at least one excitation angle variable resonator, at least one of the duty ratio, the electrode finger pitch, and the thicknesses of the first electrode fingers 16A and the second electrode fingers 17A varies depending on the excitation angle θ C_prop It is preferable that at least one of these parameters is changed according to the excitation angle θ so that the resonance frequency or the anti-resonance frequency is approximately equal in at least a part of the intersection region J. C_prop It is preferable that at least one of these parameters is changed according to the excitation angle θ so that the resonance frequency or anti-resonance frequency is approximately the same in the entire intersection region J. C_prop It is more preferable that the excitation angle is changed according to the excitation angle. This makes it possible to more reliably improve the resonance characteristics of the excitation angle variable resonator.

[0105] Alternatively, when the thickness of the intermediate layer 5 in the piezoelectric substrate 2 or the like affects the frequency, the parameter is set to the excitation angle θ C_prop In the case where the dielectric film 8 is provided on the piezoelectric substrate 2 so as to cover the first IDT electrode 18A as in the first embodiment, the thickness of the dielectric film 8 may be changed in accordance with the excitation angle θ C_prop The parameters of the first IDT electrode 18A or a plurality of parameters other than the first IDT electrode 18A may be changed in accordance with the excitation angle θ C_prop Even in these cases, the resonant frequency or anti-resonant frequency can be made substantially the same in at least a part or the entirety of the intersection region J.

[0106] The excitation angle θ of the first IDT electrode 18A of at least one excitation angle variable resonator C_prop In the portion where the excitation angle θ is the same, it is preferable that at least one of the electrode finger pitch and the duty ratio is constant. C_prop It is more preferable that both the electrode finger pitch and the duty ratio are constant in the portion where the electrode finger pitch and duty ratio are the same, thereby making it possible to more reliably improve the resonance characteristics of the excitation angle variable resonator.

[0107] When the electrode fingers of the first IDT electrode 18A have an arc shape in a plan view as in the first embodiment, it is preferable to have the following configuration.

[0108] It is preferable that the shape of the plurality of first offset electrodes 12A and the plurality of second offset electrodes 13A in a plan view is an arc shape. It is more preferable that the shape of the plurality of first offset electrodes 12A and the plurality of second offset electrodes 13A in a plan view is a shape corresponding to each of the arcs of the plurality of concentric circles. In this case, the centers of the circles including the arcs in the shapes of the plurality of offset electrodes coincide. More specifically, in the first embodiment, the centers of the circles including the arcs in the shapes of the plurality of electrode fingers and the plurality of offset electrodes coincide. This makes it possible to effectively suppress leakage from the crossing region J of the main mode.

[0109] It is preferable that the shape of the reflector electrode fingers of reflector 9A and reflector 9B in a plan view corresponds to each of the arcs of the concentric circles. It is more preferable that the center of the circle including the arc in the shape of the electrode fingers of first IDT electrode 18A and the reflector electrode fingers of each reflector coincide with each other. This can more reliably improve the resonance characteristics.

[0110] The shape of the electrode fingers in plan view may include an elliptical arc shape. More specifically, in this case, the shape of the electrode fingers in plan view includes shapes corresponding to the elliptical arcs of a plurality of ellipses having the same center of gravity. The center of gravity here refers to the center of the two focal points of the ellipse. In this case, as in the first embodiment, the acoustic wave device can suppress unwanted waves outside the band. When the shape of the electrode fingers including the arc is an ellipse, the ellipse coefficient α2 / α1 is other than 1.

[0111] When the shape of the electrode fingers in a plan view includes an elliptical arc, it is preferable that the shape of the offset electrodes in a plan view also includes an elliptical arc. In this case, it is preferable that the centers of gravity of the ellipses including the elliptical arcs in the shapes of the electrode fingers and the offset electrodes coincide with each other. This makes it possible to effectively suppress leakage from the crossing region J of the main mode.

[0112] When the shape of the plurality of electrode fingers in a plan view includes an elliptical arc, it is preferable that the shape of the plurality of reflector electrode fingers of each reflector in a plan view also includes an elliptical arc. In this case, it is preferable that the center of gravity of the ellipse including the elliptical arc in the shape of the plurality of electrode fingers and the shape of the plurality of reflector electrode fingers coincides. This makes it possible to more reliably improve the resonance characteristics.

[0113] Examples of materials for each member of the piezoelectric substrate 2 are given below.

[0114] As the material of the support substrate 4 shown in FIG. 4, for example, a piezoelectric material such as aluminum nitride, lithium tantalate, lithium niobate, or quartz; a ceramic material such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, spinel, or sialon; a dielectric material such as aluminum oxide, silicon oxynitride, DLC (diamond-like carbon), or diamond; or a semiconductor material such as silicon; or a material mainly composed of the above materials may be used. The spinel includes an aluminum compound containing one or more elements selected from Mg, Fe, Zn, Mn, and the like, and oxygen. Examples of the spinel include MgAl2O4, FeAl2O4, ZnAl2O4, and MnAl2O4. The support substrate 4 is preferably made of high-resistance silicon. The material of the support substrate 4 desirably has a volume resistivity of 1000 Ω·cm or more. In the first embodiment, high-resistance silicon is used as the material of the support substrate 4.

[0115] The first layer 5a of the intermediate layer 5 is a high acoustic velocity film. A high acoustic velocity film is a film with a relatively high acoustic velocity. More specifically, the acoustic velocity of the bulk wave propagating through the high acoustic velocity film is higher than the acoustic velocity of the elastic wave propagating through the piezoelectric layer 6. The material of the first layer 5a, which is a high acoustic velocity film, may be, for example, a piezoelectric material such as aluminum nitride, lithium tantalate, lithium niobate, or quartz; a ceramic material such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, spinel, or sialon; a dielectric material such as aluminum oxide, silicon oxynitride, DLC (diamond-like carbon), or diamond; or a semiconductor material such as silicon; or a material mainly composed of the above-mentioned material. The spinel includes an aluminum compound containing one or more elements selected from Mg, Fe, Zn, Mn, and the like, and oxygen. Examples of the spinel include MgAl2O4, FeAl2O4, ZnAl2O4, and MnAl2O4. In the first embodiment, silicon nitride is used as the material for the first layer 5a.

[0116] The second layer 5b of the intermediate layer 5 is a low acoustic velocity film. The low acoustic velocity film is a film with a relatively low acoustic velocity. More specifically, the acoustic velocity of the bulk wave propagating through the low acoustic velocity film is lower than that of the bulk wave propagating through the piezoelectric layer 6. The material of the second layer 5b, which is a low acoustic velocity film, can be, for example, a dielectric material such as glass, silicon oxide, silicon oxynitride, lithium oxide, tantalum oxide, or a compound of silicon oxide with fluorine, carbon, or boron added, or a material containing the above material as a main component. In the first embodiment, silicon oxide is used as the material of the second layer 5b.

[0117] 4 may be made of, for example, lithium tantalate, lithium niobate, zinc oxide, aluminum nitride, quartz crystal, or PZT (lead zirconate titanate). It is preferable to use lithium tantalate or lithium niobate as the material for the piezoelectric layer 6. In the first embodiment, lithium tantalate is used as the material for the piezoelectric layer 6.

[0118] In the first embodiment, a first layer 5a serving as a high acoustic velocity film, a second layer 5b serving as a low acoustic velocity film, and a piezoelectric layer 6 are laminated in this order in the piezoelectric substrate 2. This allows the energy of the elastic wave to be effectively trapped on the piezoelectric layer 6 side.

[0119] The first IDT electrode 18A, the second IDT electrode 18B, and each reflector may be made of one or more metals selected from the group consisting of Ti, Mo, Ru, W, Al, Pt, Ir, Cu, Cr, and Sc. The first IDT electrode 18A, the second IDT electrode 18B, and each reflector may be made of a single-layer metal film or a multilayer metal film. In the first embodiment, the first IDT electrode 18A, the second IDT electrode 18B, and each reflector are made of Al.

[0120] In this specification, the term "main component" refers to a component that accounts for more than 50% by weight. The main component material may be in any one of single crystal, polycrystalline, and amorphous states, or a mixture of these states.

[0121] The following describes first to ninth modified examples of the first embodiment, which differ from the first embodiment only in the configuration of the first acoustic wave resonator. In the first to ninth modified examples, as in the first embodiment, unwanted waves outside the band can be suppressed.

[0122] FIG. 8 is a schematic plan view of an elastic wave device according to a first modified example of the first embodiment.

[0123] The first envelope E1C in the first acoustic wave resonator 1C has a plurality of portions that are inclined with respect to the propagation axis of the piezoelectric layer 6. The first envelope E1C has a plurality of bends V1. More specifically, a bend is a portion where the extension direction of the envelope changes. In this modification, the first envelope E1C has a wavy shape in which adjacent bends V1 are connected by straight lines. The first envelope E1C may have a wavy shape in which adjacent bends V1 are connected by curved lines.

[0124] Similarly, the second envelope E2C also has a plurality of portions that are inclined with respect to the propagation axis. The second envelope E2C has a plurality of bent portions V2. The shape of the second envelope E2C is a wavy shape in which adjacent bent portions V2 are connected by straight lines. Note that the shape of the second envelope E2C may also be a wavy shape in which adjacent bent portions V2 are connected by curved lines.

[0125] As described above, in this modification, both the first envelope E1C and the second envelope E2C have multiple bends. However, at least one of the first envelope E1C and the second envelope E2C may have at least one bend.

[0126] The first IDT electrode 18C has a plurality of segments, with the boundaries being electrode fingers passing through the bent portion V1 of the first envelope E1C. The plurality of segments are aligned in the direction in which the propagation axis extends. Specifically, the first IDT electrode 18C has five segments.

[0127] Fig. 9 is a schematic plan view of a first acoustic wave resonator according to a first modified example of the first embodiment, in which four segments are shown.

[0128] The adjacent portion of first electrode finger 16C includes a portion of first electrode finger 16C that is located on first envelope E1C and is adjacent to a tip of any of second electrode fingers 17C. The adjacent portion of second electrode finger 17C includes a portion of second electrode finger 17C that is located on second envelope E2C and is adjacent to a tip of any of first electrode fingers 16C. The tip of an electrode finger is defined as a portion within a range of about 1λ along the extension direction of the electrode finger. The range of the adjacent portion is also defined as a range of about 1λ along the extension direction of the electrode finger. The electrode finger pitch that serves as the reference for the range of the tip and adjacent portions is, for example, an excitation angle θ C_prop The electrode finger pitch may be the narrowest in the portion where the angle is 0°.

[0129] In a first acoustic wave resonator 1C as an excitation angle variable resonator of this modification, the shape of the first electrode fingers 16C and the second electrode fingers 17C in a plan view is a shape in which the curvature changes gently. Specifically, the shape of the first electrode fingers 16C and the second electrode fingers 17C in a plan view is a shape that can be approximated to a circular arc. In the intersection region J, the excitation direction and excitation angle θ of the acoustic wave C_prop However, this is not uniform.

[0130] However, for example, the shape of the plurality of first electrode fingers 16C and the plurality of second electrode fingers 17C in a plan view may be a shape that can be approximated to an elliptical arc. Note that the shape of each electrode finger in a plan view does not necessarily have to be a shape that can be approximated to a circular arc or an elliptical arc. In this case, for example, the shape of each electrode finger in a plan view may be a parabola that cannot be approximated to a circular arc or an elliptical arc.

[0131] It is preferable that all the electrode fingers of the first IDT electrode 18C have different curved shapes in a plan view. Three types of examples are specifically shown. As an example of the first type, it is preferable that the curvatures are different between the tips located on the first envelope E1C side of all the first electrode fingers 16C and all the second electrode fingers 17C, between the adjacent parts, or between the tips and the adjacent parts. More specifically, it is preferable that the curvatures are different between the tips of all the second electrode fingers 17C, between the adjacent parts of all the first electrode fingers 16C, and between the tips of all the second electrode fingers 17C and the adjacent parts of all the first electrode fingers 16C.

[0132] As an example of the second type, it is preferable that the curvatures be different between the tips, between the adjacent parts, or between the tips and the adjacent parts of all first electrode fingers 16C and all second electrode fingers 17C located on the second envelope curve E2C side. More specifically, it is preferable that the curvatures be different between the tips of all first electrode fingers 16C, between the adjacent parts of all second electrode fingers 17C, and between the tips of all first electrode fingers 16C and the adjacent parts of all second electrode fingers 17C.

[0133] As a third example, the excitation angle θ C_prop It is preferable that the curvature differs between the portions located in the portion where the angle is 0°. In this manner, by having all the electrode fingers of the first IDT electrode 18C have different curved shapes in a plan view, it is possible to more reliably and effectively suppress unwanted waves.

[0134] This modified example satisfies all of the above three examples, provided that in at least one pair of electrode fingers among the plurality of first electrode fingers 16C and the plurality of second electrode fingers 17C, the curvatures between the tip ends located on the first envelope curve E1C side, between the adjacent portions, or between the tip ends and the adjacent portions are different from each other.

[0135] As in the first embodiment, in this modified example, the intersection region J is composed of one curved region. In the curved region, the shape of the multiple electrode fingers in a planar view is a curve that is neither a circular arc nor an elliptical arc. The shape of the multiple electrode fingers in a planar view is a shape that can be approximated to a circular arc. In other words, the shape of the multiple electrode fingers appears to be approximated to a circular arc when viewed in a planar view. In addition, the shapes of the multiple electrode fingers in a planar view are mutually different curved shapes. Therefore, the relationship shown in FIG. 10 is established.

[0136] FIG. 10 is a schematic plan view showing a circle including an arc when the shape of an electrode finger in a plan view of a first IDT electrode in a first modification of the first embodiment is approximated to the arc.

[0137] 10, two circles R1 and R2 are indicated by dashed lines. The circles R1 and R2 are circles that include arcs when the shapes of two different electrode fingers in a plan view are approximated to arcs. The position of the center O1 of the circle R1 and the position of the center O2 of the circle R2 are different from each other.

[0138] In the curved region, when the shapes of all first electrode fingers 16C and all second electrode fingers 17C in a plan view are approximated to arcs, it is preferable that the positions of the centers of the circles including the arcs are different from each other. In this case, as described above, the shapes of all electrode fingers in first IDT electrode 18C in a plan view are different curved shapes from each other. This makes it possible to more reliably and effectively suppress unwanted waves. However, in the curved region, it is only necessary that the positions of the centers of the circles including the arcs are different from each other when the shapes of at least one set of electrode fingers among multiple first electrode fingers 16C and multiple second electrode fingers 17C in a plan view are approximated to arcs.

[0139] In the curved region, the shapes of the first electrode fingers 16C and the second electrode fingers 17C in a planar view may be approximated to elliptical arcs. In this case, it is preferable that, when the shapes of all the first electrode fingers 16C and all the second electrode fingers 17C in a planar view are approximated to elliptical arcs in the curved region, the positions of the centers of gravity of the ellipses including the elliptical arcs are different from each other. However, it is only necessary that, when the shapes of at least one set of electrode fingers among the first electrode fingers 16C and the second electrode fingers 17C in a curved region are approximated to elliptical arcs in a planar view, the positions of the centers of gravity of the ellipses including the elliptical arcs are different from each other.

[0140] Returning to FIG. 8, the excitation angle θ of the portion located at the end of the first envelope E1C or the bend V1 C_prop The first envelope excitation angle θ C_AP1_m m is a natural number. The first envelope excitation angle θ C_AP1_m can be defined for the end of the first envelope E1C or each bent portion V1. Specifically, the excitation angle θ on the first envelope is defined in order from the end and bent portion V1 on the inside of the first IDT electrode 18C. C_AP1_m In this way, m is set to 1, 2, 3, etc. The excitation angle θ C_AP1_m For example, the excitation angle θ of the part located at the inner end is C_prop The first envelope excitation angle θ C_AP1_1 The excitation angle θ at the innermost bend V1 C_prop The first envelope excitation angle θ C_AP1_2 It is.

[0141] Similarly, the excitation angle θ of the end of the second envelope E2C or the part located at the bend V2 C_prop The second envelope excitation angle θ C_AP2_m The excitation angle θ on the second envelope of the part located inside C_AP2_m The value of m is assumed to be smaller.

[0142] The shape of reflector 9E and reflector 9F corresponds to the shape of first IDT electrode 18C. The shape of each reflector electrode finger of reflector 9E and reflector 9F is curved in a plan view.

[0143] Fig. 11 is a schematic plan view of an elastic wave device according to a second modified example of the first embodiment. Fig. 12 is a schematic plan view of a first elastic wave resonator in the second modified example of the first embodiment. Fig. 12 shows three segments.

[0144] As shown in FIG. 11, in a first acoustic wave resonator 1D, the shape of the plurality of electrode fingers in a plan view is not curved. Specifically, as shown in FIG. 12, in a first IDT electrode 18D, the shape of the plurality of first electrode fingers 16D and the plurality of second electrode fingers 17D in a plan view is bent at multiple nodes. More specifically, the shape of the plurality of first electrode fingers 16D and the plurality of second electrode fingers 17D in a plan view is a shape in which straight lines are connected to each other at each node. In this modification, each electrode finger is bent as a whole so as to be convex toward the right in FIG. 12. The shape of each electrode finger in a plan view can be approximated to a circular arc, an elliptical arc, or a parabola.

[0145] Fig. 13 is a schematic plan view showing parallel regions and non-parallel regions in a second modified example of the first embodiment. In Fig. 13, each region is shown with hatching. Note that parallel regions and regions extending from parallel regions, which will be described later, are shown with the same hatching. Non-parallel regions and regions extending from non-parallel regions, which will be described later, are shown with the same hatching.

[0146] The intersection region J has a plurality of parallel regions A and a plurality of non-parallel regions B. Specifically, the parallel region A is a region in which the first electrode fingers 16D and the second electrode fingers 17D extend in parallel. In this specification, the term "parallel" means that the electrode fingers extend in parallel, not only in a strictly parallel manner, but also in a substantially parallel manner. Specifically, for example, the electrode fingers extend in parallel even when the angle between the direction in which one electrode finger extends and the direction in which the other electrode finger extends is within a range of ±1°. On the other hand, the non-parallel region B is a region in which the directions in which the first electrode fingers 16D and the second electrode fingers 17D extend cross each other. The intersection region J may include at least two parallel regions A and at least one non-parallel region B.

[0147] In first IDT electrode 18D, some of the parallel regions A and some of the non-parallel regions B each include a portion of all of the first electrode fingers 16D and a portion of all of the second electrode fingers 17D. The other parallel regions A each include a portion of the first electrode fingers 16D and a portion of the second electrode fingers 17D. The remaining electrode fingers are not included in the parallel regions A. The same is true for the other non-parallel regions B. However, all of the parallel regions A and all of the non-parallel regions B may each include a portion of all the electrode fingers.

[0148] The parallel regions A and the non-parallel regions B are arranged alternately. The first electrode fingers 16D and the second electrode fingers 17D extend linearly in the parallel regions A and the non-parallel regions B, respectively, and are bent at the boundaries between the parallel regions A and the non-parallel regions B.

[0149] In the parallel regions A, the directions in which the electrode fingers extend are different from each other. Therefore, in the intersection region J, the excitation direction and excitation angle θ C_prop However, this is not uniform.

[0150] The shape of the reflector electrode fingers of the reflectors 9G and 9H in a plan view is bent at multiple nodes, similar to each electrode finger of the first IDT electrode 18D. Specifically, the reflector electrode fingers extend linearly in a region extending from the parallel region A and a region extending from the non-parallel region B. The reflector electrode fingers are bent at the boundary between the region extending from the parallel region A and the region extending from the non-parallel region B. This makes it possible to more reliably improve the resonance characteristics.

[0151] In this modification, the shape of some of the first offset electrodes 12D and some of the second offset electrodes 13D in a plan view is a bent shape in which straight lines are connected to each other. The shape of the remaining offset electrodes in a plan view is linear. Note that the shape of all of the first offset electrodes 12D and all of the second offset electrodes 13D in a plan view may be a bent shape or a linear shape.

[0152] FIG. 14 is a schematic plan view of a first acoustic wave resonator according to a third modification of the first embodiment.

[0153] In this modification, the electrode fingers of the first IDT electrode 18E include linear portions. Specifically, the intersection region of the first IDT electrode 18E has a first region W1, a second region W2, and a third region W3. The first region W1, the second region W2, and the third region W3 are arranged in a direction in which the first bus bar 14A and the second bus bar 15A face each other. More specifically, the first region W1 and the second region W2 face each other with the third region W3 in between. The first region W1 is located on the first bus bar 14A side. The second region W2 is located on the second bus bar 15A side. In the third region W3, the shape of the electrode fingers in a plan view is linear. In the intersection region, the excitation direction and excitation angle θ of the acoustic wave are C_prop However, this is not uniform.

[0154] On the other hand, in the first region W1 and the second region W2, the shape of the multiple electrode fingers in a plan view is an elliptical arc shape. Thus, each electrode finger includes a portion whose shape in a plan view has a different curvature. Note that, in the first region W1 and the second region W2, the shape of the multiple electrode fingers in a plan view may be a circular arc shape. Alternatively, in the first region W1 and the second region W2, the shape of the multiple electrode fingers in a plan view may be a curved shape that can be approximated to a circular arc or an elliptical arc.

[0155] In this modification, in the entire third region W3, the direction in which the propagation axis of the piezoelectric layer 6 extends is perpendicular to the direction in which the electrode fingers extend. C_prop is 0°. Therefore, the third region W3 is a stable region with respect to the propagation axis. By including the third region W3 in the crossing region, it is possible to suppress deterioration of the fractional bandwidth. The fractional bandwidth is expressed by |fr-fa| / fr×100[%], where fr is the resonant frequency and fa is the anti-resonant frequency. Note that the excitation angle θ in the third region W3 is C_prop is not limited to 0°.

[0156] FIG. 15 is a schematic plan view of a first acoustic wave resonator according to a fourth modification of the first embodiment.

[0157] In the first acoustic wave resonator of this modified example, the intersection region has a plurality of curved regions. Specifically, the plurality of curved regions are a first curved region K1 and a second curved region K2. The first curved region K1 includes a first envelope E1. The second curved region K2 includes a second envelope E2. The boundary between the first curved region K1 and the second curved region K2 is linear.

[0158] In this modification, in each curved region, the shape of the first electrode fingers 16F and the second electrode fingers 17F in plan view is a single arc shape. Each of the electrode fingers in plan view is a shape in which two arcs are connected. In each electrode finger, the two curved shapes are inverted from each other at the boundary between the first curved region K1 and the second curved region K2.

[0159] Specifically, in the first curved region K1, the electrode fingers are curved so as to convex toward the right in Fig. 15. The arcs in the shapes of the portions of the electrode fingers located in the first curved region K1 correspond to the arcs in the multiple concentric circles. Therefore, the centers of the circles including the arcs in the shapes of the electrode fingers in the first curved region K1 are aligned.

[0160] On the other hand, in the second curved region K2, the multiple electrode fingers are curved so as to convex leftward in Fig. 15. The arcs in the shapes of the multiple electrode fingers located in the second curved region K2 are the respective arcs of multiple concentric circles. Therefore, the centers of the circles including the arcs in the shapes of the multiple electrode fingers in the second curved region K2 are aligned.

[0161] The center of a circle including arcs in the shapes of the multiple electrode fingers in the first curved region K1 and the center of a circle including arcs in the shapes of the multiple electrode fingers in the second curved region K2 face each other across the first IDT electrode 18F.

[0162] In this way, the shapes of the first electrode fingers 16F and the second electrode fingers 17F in a plan view may each include at least two curved portions in which the first electrode fingers 16F and the second electrode fingers 17F bend in different directions in the crossing region. In this case, in the crossing region, the excitation direction and excitation angle θ of the acoustic wave C_prop However, this is not uniform.

[0163] In each curved region, the shape of the electrode fingers in plan view may be a single elliptical arc, or may be a curved shape that can be approximated to a single circular or elliptical arc.

[0164] Like the electrode fingers of the first IDT electrode 18F, the reflector electrode fingers of each reflector have a shape in plan view that is formed by connecting two circular arcs. The reflector electrode fingers may have a shape in plan view that is formed by connecting two elliptical arcs. Alternatively, the reflector electrode fingers may have a shape in plan view that is formed by connecting two curved lines that can be approximated to a circular arc or an elliptical arc.

[0165] In this modification, both the first envelope E1 and the second envelope E2 are linear and extend parallel to each other. The first envelope E1 and the second envelope E2 extend at an angle to the propagation axis of the piezoelectric layer 6.

[0166] FIG. 16 is a schematic plan view of a first acoustic wave resonator according to a fifth modification of the first embodiment.

[0167] The intersection region J of the first IDT electrode 18G has a central region F and a pair of edge regions. Specifically, the pair of edge regions are a first edge region H1 and a second edge region H2. The first edge region H1 includes a first envelope E1 as an edge portion. The second edge region H2 includes a second envelope E2 as an edge portion. The first edge region H1 and the second edge region H2 face each other with the central region F in between. It should be noted that each intersection region in the other embodiments and modified examples also has a first edge region, a second edge region, and a central region.

[0168] First edge region H1 is defined as a region where the tip of second electrode finger 17G and the adjacent portion of first electrode finger 16G are located. That is, first edge region H1 is defined as a region in a range of about 1λ from the tip of second electrode finger 17G along the direction in which the electrode fingers extend, based on second electrode finger 17G. Similarly, second edge region H2 is defined as a region in a range of about 1λ from the tip of first electrode finger 16G along the direction in which the electrode fingers extend, based on first electrode finger 16G.

[0169] Each electrode finger of the first IDT electrode 18G has a wide portion in the first edge region H1 and the second edge region H2. The width of the electrode finger in the wide portion is wider than the width of the electrode finger in the central region F.

[0170] Specifically, the first electrode finger 16G has a wide portion 16a in the first edge region H1. The second electrode finger 17G also has a wide portion 17a in the first edge region H1. Meanwhile, the first electrode finger 16G has a wide portion 16b in the second edge region H2. The second electrode finger 17G also has a wide portion 17b in the second edge region H2. As a result, the sound velocity in the first edge region H1 and the second edge region H2 is lower than the sound velocity in the central region F. As a result, a low sound velocity region is formed in the first edge region H1 and the second edge region H2. The low sound velocity region is a region where the sound velocity is lower than the sound velocity in the central region F.

[0171] In this modification, the central region F and a pair of low sound velocity regions are arranged in this order from the inside to the outside in the direction in which the first busbar 14A and the second busbar 15A face each other. This establishes a piston mode. This makes it possible to suppress the transverse mode. In addition, the energy of the main mode can be effectively confined to the center side of the intersection region J, making it possible to improve the characteristics of the main mode.

[0172] The configuration of the first IDT electrode 18G is the same as that of the first embodiment except for the first edge region H1 and the second edge region H2. C_prop However, this is not uniform.

[0173] In at least one of the first edge region H1 and the second edge region H2, at least one electrode finger may have a wide portion. However, in at least one of the first edge region H1 and the second edge region H2, it is preferable that a plurality of electrode fingers have a wide portion, and it is more preferable that all electrode fingers have a wide portion. In both the first edge region H1 and the second edge region H2, it is more preferable that a plurality of electrode fingers have a wide portion, and it is even more preferable that all electrode fingers have a wide portion. This makes it possible to more reliably establish the piston mode.

[0174] The electrode fingers of the first IDT electrode 18G have an arc shape in a plan view. However, the configuration in which a low acoustic velocity region is provided in the first edge region H1 or the second edge region H2 of the acoustic wave resonator may also be adopted in other configurations of the present invention in which the electrode fingers have a different shape from that of this modified example.

[0175] In the first IDT electrode 18G, the width of each electrode finger is wide over the entire edge region. The shape of each wide portion in a plan view is rectangular. However, each electrode finger may be wide in at least a part of each edge region. The shape of each wide portion in a plan view is not limited to a rectangular shape. Each reflector electrode finger of each reflector may also be wide in a portion located on an extension of the first edge region H1 and a portion located on an extension of the second edge region H2.

[0176] 17, a plurality of mass adding films 19 are provided, thereby forming low acoustic velocity regions in the first edge region H1 and the second edge region H2. Specifically, in the first edge region H1, mass adding films 19 are provided on each of the first electrode fingers 16A and each of the second electrode fingers 17A. The same is true in the second edge region H2. The configuration of the first IDT electrode 18A is the same as that of the first embodiment.

[0177] In this modification, each mass-adding film 19 is provided only on one electrode finger. In this case, the material of the mass-adding film 19 can be an appropriate metal or dielectric. However, the mass-adding film 19 may be provided over a plurality of electrode fingers. In this case, the material of the mass-adding film 19 can be an appropriate dielectric.

[0178] The mass adding film 19 may be laminated with at least one of the plurality of electrode fingers in at least one of the first edge region H1 and the second edge region H2. Specifically, the mass adding film 19 may be provided so as to overlap at least one of the plurality of first electrode fingers 16A and the plurality of second electrode fingers 17A in at least one of the first edge region H1 and the second edge region H2 in a plan view. In this case, a low acoustic velocity region is formed in at least a part of at least one of the first edge region H1 and the second edge region H2.

[0179] In at least one of the first edge region H1 and the second edge region H2, it is preferable that a plurality of electrode fingers are laminated with the mass addition film 19, and it is more preferable that all of the electrode fingers are laminated with the mass addition film 19. Alternatively, it is more preferable that a plurality of electrode fingers are laminated with the mass addition film 19 in both the first edge region H1 and the second edge region H2. This makes it possible to more reliably establish the piston mode. It is even more preferable that all of the electrode fingers are laminated with the mass addition film 19 in both edge regions. In this case, the low sound velocity region is formed in the entirety of both edge regions. This makes it possible to more reliably establish the piston mode.

[0180] In the portion where the electrode fingers and the mass addition film 19 are laminated, they are laminated in the order of the piezoelectric substrate 2, the electrode fingers, and the mass addition film 19. However, in the portion where the electrode fingers and the mass addition film 19 are laminated, they may be laminated in the order of the piezoelectric substrate 2, the mass addition film 19, and the electrode fingers. In other words, the mass addition film 19 may be provided between the piezoelectric substrate 2 and the electrode fingers. In each reflector electrode finger of each reflector, a portion located on an extension of the first edge region H1 and a portion located on an extension of the second edge region H2 may also be laminated with the mass addition film 19.

[0181] The mass addition film 19 may be made of the same metal as that used for each electrode finger. This configuration corresponds to the seventh modified configuration shown in FIG. 18(a) and FIG. 18(b). That is, as shown in FIG. 18(a), in the first IDT electrode 18H, the thickness of the first electrode finger 16H in the first edge region H1 and the second edge region H2 is thicker than the thickness of the first electrode finger 16H in the central region F. As shown in FIG. 18(b), the thickness of the second electrode finger 17H in the first edge region H1 and the second edge region H2 is thicker than the thickness of the second electrode finger 17H in the central region F. As a result, low acoustic velocity regions are formed in the first edge region H1 and the second edge region H2, respectively.

[0182] 18(a) shows a schematic cross section of first electrode finger 16H along the extension direction of first electrode finger 16H. Similarly, FIG. 18(b) shows a schematic cross section of second electrode finger 17H along the extension direction of second electrode finger 17H. The configuration of first IDT electrode 18H is similar to that of the first embodiment except for first edge region H1 and second edge region H2.

[0183] It is sufficient that the thickness of at least one electrode finger in at least one of the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode finger in the central region F. However, it is preferable that the thickness of each of the multiple electrode fingers in at least one of the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode finger in the central region F. It is more preferable that the thickness of each of the electrode fingers in at least one of the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode finger in the central region F.

[0184] It is more preferable that the thickness of each of the plurality of electrode fingers in both the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode fingers in the central region F. It is even more preferable that the thickness of each of the electrode fingers in both the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode fingers in the central region F. This makes it possible to more reliably establish the piston mode.

[0185] In this modification, the thickness of each electrode finger is thickened over the entire edge region. However, the thickness of each electrode finger may be thickened in at least a part of each edge region. Each reflector electrode finger of each reflector may also be thickened in a portion located on an extension of the first edge region H1 and a portion located on an extension of the second edge region H2. The low acoustic velocity region may be provided by at least one of the configurations of the fifth to seventh modifications. For example, the low acoustic velocity region may be provided by more than one of the configurations of the fifth to seventh modifications.

[0186] FIG. 19 is a schematic plan view of a first acoustic wave resonator according to an eighth modification of the first embodiment.

[0187] The configuration of the first IDT electrode 18I in this modification is the same as the configuration of the first IDT electrode 18G in the fifth modification, except for the first offset electrode 12I and the second offset electrode 13I. Therefore, in the crossing region J, the excitation direction and excitation angle θ C_prop However, the width of the tip of the first offset electrode 12I of this modification is wider than the width of the other parts of the first offset electrode 12I. The width of the tip of the second offset electrode 13I is wider than the width of the other parts of the second offset electrode 13I.

[0188] FIG. 20 is a schematic plan view of an elastic wave device according to a ninth modification of the first embodiment.

[0189] In the first IDT electrode 18J of the first acoustic wave resonator 1J, the first envelope E1 and the second envelope E2 extend parallel to the direction in which the propagation axis of the piezoelectric layer 6 extends. The shape of the first IDT electrode 18J in a plan view is an arc shape, similar to the first embodiment. Therefore, in the crossing region, the excitation direction and excitation angle θ of the acoustic wave C_prop However, this is not uniform.

[0190] The direction in which the first envelope E1 extends may be parallel to the direction in which the second envelope E2 extends and may intersect with the direction in which the propagation axis extends.

[0191] The shape of the electrode fingers in a plan view may be an elliptical arc. Alternatively, the shape of the electrode fingers in a plan view may be a curved shape that can be approximated as a circular arc or an elliptical arc, or a parabolic shape that cannot be approximated as a circular arc or an elliptical arc. On the other hand, the shape of the electrode fingers in a plan view may be a shape that is bent at multiple nodes, as in the second modification.

[0192] FIG. 21 is a schematic plan view of an elastic wave device according to a second preferred embodiment of the present invention.

[0193] This embodiment differs from the first embodiment in the configuration of second acoustic wave resonator 21B. Meanwhile, first acoustic wave resonator 1D has the same configuration as that of the second modified example of the first embodiment. Except for the above points, acoustic wave device 21 of this embodiment has the same configuration as that of the first embodiment. Note that second acoustic wave resonator 21B is an acoustic wave resonator that is not an excitation angle variable resonator.

[0194] In the second acoustic wave resonator 21B, the third envelope E3 and the fourth envelope E4 of the second IDT electrode 28B extend at an incline with respect to the propagation axis of the piezoelectric layer 6. The third envelope E3 and the fourth envelope E4 are linear and extend parallel to each other. In this manner, the second IDT electrode 28B is an inclined IDT electrode. In the second acoustic wave resonator 21B, the transverse mode can be suppressed.

[0195] Furthermore, similar to the second modification of the first embodiment, elastic wave device 21 of this preferred embodiment includes first elastic wave resonator 1D, which is an excitation angle variable resonator, and thus can suppress unwanted waves outside the band.

[0196] First acoustic wave resonator 1D of acoustic wave device 21 may have a configuration of an excitation angle variable resonator according to the present invention other than the second modification of the first preferred embodiment.

[0197] FIG. 22 is a schematic plan view of an elastic wave device according to a third preferred embodiment of the present invention.

[0198] This embodiment differs from the first embodiment in that both first elastic wave resonator 31A and second elastic wave resonator 41C are excitation angle variable resonators. Except for the above, elastic wave device 31 of this embodiment has a similar configuration to elastic wave device 1 of the first embodiment.

[0199] The first acoustic wave resonator 31A has a configuration similar to that of the first acoustic wave resonator 1A in the first preferred embodiment. The second acoustic wave resonator 41C has a configuration similar to that of the first acoustic wave resonator 1C in the first modified example of the first preferred embodiment. In this preferred embodiment, the first acoustic wave resonator 31A and the second acoustic wave resonator 41C are excitation angle change type resonators, and have different configurations in their crossing regions.

[0200] In the first acoustic wave resonator 31A, the plurality of electrode fingers are curved so as to convex toward the right in FIG. 22. On the other hand, in the second acoustic wave resonator 41C, the plurality of electrode fingers are curved so as to convex toward the left in FIG.

[0201] The phase characteristics were compared between elastic wave device 31 having the configuration of this preferred embodiment and an elastic wave device of a comparative example shown in FIG. 6. The results of the first preferred embodiment are also shown. The design parameters of the first preferred embodiment and the comparative example are similar to those of the first preferred embodiment and the comparative example shown in FIG. 7. The design parameters of an elastic wave resonator having the configuration of first elastic wave resonator 31A in this preferred embodiment are as follows:

[0202] Support substrate: Material: Si, surface orientation: (111), Euler angles (φ, θ, ψ) are 73° First intermediate layer: Material: SiN, thickness: 0.15λ Second layer of the intermediate layer: Material: SiO2, thickness: 0.15λ Piezoelectric layer: Material: Rotated Y-cut 55°X-propagation LiTaO3, thickness: 0.2λ First IDT electrode: Material: Al, thickness: 0.05λ Dielectric film: Material: SiO2, thickness: 0.015λ Crossing angle θ C1_AP :5° Crossing angle θ C2_AP : -5° Wavelength λ: Excitation angle θ C_prop 2μm at 0° Number of pairs of electrode fingers of the first IDT electrode: 80 pairs Duty ratio: excitation angle θ C_propis 0.5 at 0°, and the absolute value of the excitation angle |θ C_prop The larger |, the smaller. Gap length: 0.135λ Offset electrode length: 3.5λ Each reflector: Number of pairs of reflector electrode fingers: 20 pairs

[0203] The design parameters of an acoustic wave resonator having the configuration of second acoustic wave resonator 41C in this preferred embodiment are as follows.

[0204] Support substrate: Material: Si, surface orientation: (111), Euler angles (φ, θ, ψ) are 73° First intermediate layer: Material: SiN, thickness: 0.15λ Second layer of the intermediate layer: Material: SiO2, thickness: 0.15λ Piezoelectric layer: Material: Rotated Y-cut 55°X-propagation LiTaO3, thickness: 0.2λ First IDT electrode: Material: Al, thickness: 0.05λ Dielectric film: Material: SiO2, thickness: 0.015λ Wavelength λ: Excitation angle θ C_prop 2μm at 0° Number of pairs of electrode fingers of the first IDT electrode: 100 pairs Duty ratio: excitation angle θ C_prop 0.5 in the part where Gap length: 0.135λ Offset electrode length: 3.5λ Distance between the first envelope and the second envelope in a direction perpendicular to the propagation axis: 25 λ First envelope: Absolute value of the inclination angle with respect to the propagation axis... 20°, number of pairs of electrode fingers between bends... 20 pairs Second envelope: Absolute value of the inclination angle with respect to the propagation axis: 20°, Number of pairs of electrode fingers between bends: 20 pairs First envelope excitation angle: θ C_AP1_1 = 12°, θ C_AP1_2 = 8°, θ C_AP1_3 = 16°, θ C_AP1_4 = 10°, θ C_AP1_5 = 16°, θ C_AP1_6 =9° Second envelope excitation angle: θ C_AP2_1 = 9°, θ C_AP2_2 = 15°, θ C_AP2_3 = 8°, θ C_AP2_4 = 15.5°, θ C_AP2_5 = 10°, θ C_AP2_6 =16° Each reflector: Number of pairs of reflector electrode fingers: 20 pairs

[0205] FIG. 23 is a diagram showing phase characteristics near a frequency at which spurious waves are generated in the first embodiment, the third embodiment, and a comparative example.

[0206] 23, it can be seen that the Rayleigh waves as unwanted waves can be suppressed more effectively in the first embodiment than in the comparative example. Furthermore, it can be seen that the Rayleigh waves can be further suppressed in the third embodiment.

[0207] This is because in the third preferred embodiment, both the first elastic wave resonator 31A and the second elastic wave resonator 41C are excitation angle variable resonators. In the elastic wave device 31, unwanted waves outside the band can be suppressed in all of the elastic wave resonators. As a result, the unwanted waves outside the band can be further suppressed in the elastic wave device 31 as a whole. In addition, transverse modes can be suppressed in both the first elastic wave resonator 31A and the second elastic wave resonator 41C. Therefore, the transverse modes can be effectively suppressed in the elastic wave device as a whole.

[0208] As described above, in an elastic wave device according to the present invention, elastic wave resonators may be connected in parallel to each other. For example, in a first modification of the third embodiment shown in Fig. 24, a first elastic wave resonator 31A and a second elastic wave resonator 41C are connected in parallel to each other. In this modification, as in the third embodiment, unwanted waves outside the band can be suppressed.

[0209] When an elastic wave device has multiple excitation angle variable resonators, the combination of the configurations of the excitation angle variable resonators is not limited to that of the third embodiment. Below, second and third modified examples of the third embodiment are shown, which differ from the third embodiment only in the combination of the multiple excitation angle variable resonators. In the second and third modified examples, as in the third embodiment, unwanted waves outside the band can be suppressed.

[0210] In the second modification shown in Fig. 25, a second acoustic wave resonator 31D has a configuration similar to that of the first acoustic wave resonator 1D in the second modification of the first embodiment. Note that in the second acoustic wave resonator 31D, a plurality of electrode fingers are curved to be convex toward the left side in Fig. 25. The first acoustic wave resonator 31A has the same configuration as that of the third embodiment.

[0211] The phase characteristics were compared between an elastic wave device having the configuration of this modification and an elastic wave device of a comparative example shown in FIG. 6. The results of the first embodiment are also shown. The design parameters of the comparative first embodiment and the comparative example are similar to those of the comparative first embodiment and the comparative example shown in FIG. 23. Furthermore, the design parameters of the elastic wave resonator having the configuration of first elastic wave resonator 31A in this modification are similar to those of the comparative third embodiment shown in FIG. 23. The design parameters of the elastic wave resonator having the configuration of second elastic wave resonator 31D in this modification are as follows:

[0212] Support substrate: Material: Si, surface orientation: (111), Euler angles (φ, θ, ψ) are 73° First intermediate layer: Material: SiN, thickness: 0.15λ Second layer of the intermediate layer: Material: SiO2, thickness: 0.15λ Piezoelectric layer: Material: Rotated Y-cut 55°X-propagation LiTaO3, thickness: 0.2λ First IDT electrode: Material: Al, thickness: 0.05λ Dielectric film: Material: SiO2, thickness: 0.015λ Wavelength λ: Excitation angle θ C_prop2μm at 0° Number of pairs of electrode fingers of the first IDT electrode: 100 pairs Duty ratio: excitation angle θ C_prop 0.5 in the part where Gap length: 0.135λ Offset electrode length: 3.5λ Distance between the first envelope and the second envelope in a direction perpendicular to the propagation axis: 25 λ First envelope: Absolute value of the inclination angle with respect to the propagation axis... 20°, number of pairs of electrode fingers between bends... 20 pairs Second envelope: Absolute value of the inclination angle with respect to the propagation axis: 20°, Number of pairs of electrode fingers between bends: 20 pairs First envelope excitation angle: θ C_AP1_1 = 6.2°, θ C_AP1_2 = 6.3°, θ C_AP1_3 = 6.3°, θ C_AP1_4 = 4.4°, θ C_AP1_5 = 12°, θ C_AP1_6 =8.4° Second envelope excitation angle: θ C_AP2_1 = 14.3°, θ C_AP2_2 = 8.8°, θ C_AP2_3 = 12.5°, θ C_AP2_4 = 6°, θ C_AP2_5 = 4.2°, θ C_AP2_6 =12.3° Each reflector: Number of pairs of reflector electrode fingers: 20 pairs

[0213] FIG. 26 is a diagram showing phase characteristics near a frequency at which spurious waves are generated in the first embodiment, the second modified example of the third embodiment, and a comparative example.

[0214] 26, in this modification, Rayleigh waves, which are unnecessary waves outside the band, can be further suppressed. Although not shown, in this modification, transverse modes can also be suppressed in both first acoustic wave resonator 31A and second acoustic wave resonator 31D. Thus, transverse modes can be effectively suppressed in the entire acoustic wave device.

[0215] In the third modification shown in Fig. 27, a first acoustic wave resonator 31C has a similar configuration to the first acoustic wave resonator 1C in the first modification of the first embodiment. In the first acoustic wave resonator 31C, a plurality of electrode fingers are curved to be convex toward the right in Fig. 27. A second acoustic wave resonator 31D has a similar configuration to the third modification of the first embodiment. In the second acoustic wave resonator 31D, a plurality of electrode fingers are curved to be convex toward the left in Fig. 27.

[0216] In this modification, in all of the excitation angle changing resonators, that is, first acoustic wave resonators 31C and second acoustic wave resonators 31D, both the first envelope and the second envelope have at least one bend, thereby making it possible to effectively suppress transverse modes in the entire acoustic wave device.

[0217] In describing the configurations of the above-mentioned embodiments and modifications, several examples of excitation angle variable resonators have been shown. The following first to third configurations can be given as examples of the configurations of the crossing regions of the excitation angle variable resonators.

[0218] The first configuration is the configuration shown in the first embodiment shown in Fig. 3 and the description thereof, in other words, the shape of the multiple first electrode fingers and the multiple second electrode fingers in a plan view includes a circular arc or an elliptical arc shape.

[0219] The second configuration is a configuration of the first modified example of the first embodiment shown in Fig. 9. That is, the shape of the multiple first electrode fingers and the multiple second electrode fingers is curved in a plan view, and the curvature of each of the first electrode fingers and the second electrode fingers is not constant. The second configuration is a configuration in which the curvature differs between the tip portions located on the first envelope side, between adjacent portions, or between the tip portions and adjacent portions in at least one pair of electrode fingers among the multiple first electrode fingers and the multiple second electrode fingers.

[0220] The third configuration is a configuration of the second modified example of the first embodiment shown in FIG. 12. That is, the configuration includes a plurality of parallel regions in which the plurality of first electrode fingers and the plurality of second electrode fingers extend in parallel, and a non-parallel region in which the extending directions of the plurality of first electrode fingers and the plurality of second electrode fingers intersect with each other in the intersection region. The third configuration is a configuration in which the parallel regions and non-parallel regions are alternately arranged in at least a part of the intersection region. Furthermore, the third configuration is a configuration in which the plurality of first electrode fingers and the plurality of second electrode fingers each extend linearly in the plurality of parallel regions and non-parallel regions, and are bent at the boundary between the parallel regions and the non-parallel regions.

[0221] It is preferable that the configuration of the crossing region of at least one excitation angle changing resonator be any one of configurations 1 to 3. This makes it possible to more reliably suppress unwanted waves outside the band.

[0222] The first to third configurations refer to the types of configurations of the crossover regions. For example, when the crossover regions of both excitation angle changing resonators have the same configuration among the first to third configurations, this also includes cases where parameters such as the duty ratio and electrode finger pitch in both crossover regions are different from each other.

[0223] As in the first and second embodiments described above, at least one of the multiple elastic wave resonators may be an elastic wave resonator that is not an excitation angle variable resonator. In this case, the configuration of the crossing region of the elastic wave resonator may be any of the first to third configurations and a configuration in which the shape of the multiple electrode fingers is linear in a plan view. However, in the present invention, at least one of the multiple elastic wave resonators is an excitation angle variable resonator.

[0224] At least two of the multiple acoustic wave resonators are preferably excitation angle variable resonators, and the configurations in the crossing regions of the at least two excitation angle variable resonators are different from each other among the first to third configurations. In this case, the shapes of the electrode fingers in a plan view of the at least two excitation angle variable resonators are different from each other. This makes it possible to more reliably suppress unwanted waves outside the band in the entire acoustic wave device.

[0225] However, when the crossing regions of multiple excitation angle changing resonators have different configurations, the configuration of the crossing region of at least one excitation angle changing resonator may be a configuration other than the first to third configurations, such as the third modified example of the first embodiment shown in Figure 14.

[0226] It is more preferable that all of the acoustic wave resonators in the acoustic wave device are excitation angle variable resonators, and that the electrode finger shapes of all the excitation angle variable resonators are different from one another, thereby making it possible to more reliably suppress unwanted waves outside the band.

[0227] In the excitation angle changing resonator, the first envelope and the second envelope may have any of the following fourth to sixth configurations. The fourth configuration is a first modified example of the first embodiment shown in Fig. 9. That is, both the first envelope and the second envelope have a shape having at least one bent portion whose extension direction changes.

[0228] The fifth configuration is a configuration of the ninth modification of the first embodiment shown in Fig. 20. That is, in this configuration, both the first envelope and the second envelope are linear, and extend parallel to each other. In the fifth configuration, the direction in which the first envelope and the second envelope extend may be parallel to the direction in which the propagation axis of the piezoelectric layer 6 extends, or may intersect with the direction in which the propagation axis extends.

[0229] The sixth configuration is the configuration of the first embodiment shown in FIG. 3. That is, both the first envelope and the second envelope are linear, and the direction in which the first envelope extends and the direction in which the second envelope extends cross each other. The sixth configuration is not limited to the configuration in which the first envelope and the second envelope are arranged in line symmetry. Specifically, for example, the absolute value of the angle between the first envelope and the direction in which the propagation axis extends and the absolute value of the angle between the second envelope and the direction in which the propagation axis extends may be different from each other. In this example, the crossing angle θ C1_AP The absolute value of and the intersection angle θ C2_AP More specifically, for example, the intersection angle θ C1_AP is 10°, and the cross angle θ C2_AP Alternatively, for example, the cross angle θ C1_AP is 10°, and the cross angle θ C2_AP may be 0°.

[0230] At least two of the multiple elastic wave resonators may be excitation angle variable resonators, and the configurations of the first envelope and the second envelope in the at least two excitation angle variable resonators may be any one of the fourth to sixth configurations that are different from each other.

[0231] FIG. 28 is a schematic plan view of an elastic wave device according to a fourth preferred embodiment of the present invention.

[0232] This embodiment differs from the third embodiment in that both a first elastic wave resonator 31A and a second elastic wave resonator 41A have the same configuration as the first elastic wave resonator 31A in the third embodiment. Note that in the second elastic wave resonator 41A, a plurality of electrode fingers are curved to be convex to the left in FIG. 28. Except for the above points, the elastic wave device of this embodiment has the same configuration as the elastic wave device 31 of the third embodiment.

[0233] In this preferred embodiment, the elastic wave resonators of the elastic wave device include excitation angle variable resonators, as in the third preferred embodiment, which makes it possible to suppress unwanted waves outside the band.

[0234] The crossing regions of both the first elastic wave resonator 31A and the second elastic wave resonator 41A have the first configuration. Specifically, the shape of the plurality of electrode fingers is an arc shape in a plan view. However, the first elastic wave resonator 31A and the second elastic wave resonator 41A have different duty ratios. Therefore, the shapes of the electrode fingers in the crossing regions of the first elastic wave resonator 31A and the second elastic wave resonator 41A are different from each other.

[0235] More specifically, the excitation angle θ of the first acoustic wave resonator 31A C_prop In the portion where the absolute value of the excitation angle |θ C_prop The larger |, the smaller the duty ratio.

[0236] On the other hand, the excitation angle θ C_prop In the second acoustic wave resonator 41A, the duty ratio is 0.5 in the portion where the absolute value of the excitation angle |θ C_prop The larger |, the smaller the duty ratio.

[0237] In each of the first acoustic wave resonator 31A and the second acoustic wave resonator 41A, the duty ratio is set to an excitation angle θ C_prop Since the duty ratio varies depending on the excitation angle θ, the resonant frequency or anti-resonant frequency is approximately the same in the entire crossing region. However, the duty ratio may be constant in the entire crossing region. In this case, parameters other than the duty ratio, such as the electrode finger pitch and the electrode finger thickness, are changed depending on the excitation angle θ so that the resonant frequency or anti-resonant frequency is approximately the same in the entire crossing region. C_prop It may be changed depending on the

[0238] The elastic wave resonators of the elastic wave device may include elastic wave resonators other than the first elastic wave resonator 31A and the second elastic wave resonator 41A as excitation angle variable resonators. Even in this case, the excitation angle θC_prop It is preferable that the duty ratios at the portion where the excitation angle θ is 0° are different from each other. C_prop It is preferable that the duty ratio at the 0° portion is constant, which makes it possible for the acoustic wave device as a whole to more reliably and effectively suppress unwanted waves outside the band.

[0239] In this preferred embodiment, in all of the excitation angle varying resonators, that is, the first elastic wave resonator 31A and the second elastic wave resonator 41A, the first envelope and the second envelope have the sixth configuration. Specifically, both the first envelope and the second envelope are linear, the direction in which the first envelope extends intersects with the direction in which the second envelope extends, and the first envelope and the second envelope are arranged symmetrically with respect to the axis of symmetry passing through the center of the intersecting region. This makes it possible to effectively suppress transverse modes in the entire elastic wave device.

[0240] However, the first and second envelopes may have a configuration other than the sixth configuration. For example, in the modification of the fourth embodiment shown in FIG. 29, a first elastic wave resonator 31J and a second elastic wave resonator 41J have a configuration similar to that of the first elastic wave resonator 1J in the ninth modification of the first embodiment shown in FIG. 20. In the first elastic wave resonator 31J, the plurality of electrode fingers are bent so as to be convex toward the right in FIG. 29. In the second elastic wave resonator 41J, the plurality of electrode fingers are bent so as to be convex toward the left in FIG. 29.

[0241] In this modification, the first and second envelopes of all the excitation angle varying resonators, that is, the first elastic wave resonator 31J and the second elastic wave resonator 41J, have the sixth configuration described above. Specifically, the first and second envelopes are both linear and extend in parallel.

[0242] The duty ratios of the first acoustic wave resonator 31J and the second acoustic wave resonator 41J are the same as those in the third embodiment. More specifically, the excitation angle θ C_prop In the portion where the absolute value of the excitation angle |θ C_prop The larger |, the smaller the duty ratio.

[0243] On the other hand, the excitation angle θ C_prop In the second acoustic wave resonator 41J, the duty ratio is 0.5 in the portion where the absolute value of the excitation angle |θ C_prop The larger |, the smaller the duty ratio.

[0244] In the fourth embodiment and its modified example, the excitation angle changing resonators have the same configuration of the crossing regions, but the duty ratios are different from each other, so that the shapes of the electrode fingers are different from each other. However, the present invention is not limited to this.

[0245] For example, the electrode finger pitches of the at least two excitation angle variable resonators may be different from each other. In this case, for example, in each of the at least two excitation angle variable resonators, at least the excitation angle θ C_prop The electrode finger pitch is constant in the portion where the excitation angle θ is 0°. C_prop The electrode finger pitches at the 0° portion are different from each other.

[0246] The curvatures of the electrode fingers of the at least two excitation angle variable resonators may be different from each other. In this case, for example, the shape of the electrode fingers in a plan view is curved in each of the at least two excitation angle variable resonators. The curvatures of at least one of the outermost electrode fingers and the innermost electrode fingers of the at least two excitation angle variable resonators are different from each other.

[0247] As described above, the outward direction is the direction in which the curved portion of the electrode finger is convex in the direction in which the multiple electrode fingers are arranged. The direction opposite to the outward direction is the inward direction. More specifically, the inward direction is the direction in which the curved portion of the electrode finger is concave in the direction in which the multiple electrode fingers are arranged.

[0248] Alternatively, at least two excitation angle variable resonators have an excitation angle θ C_prop For example, the ranges of the excitation angles θ C_prop The maximum values ​​of the positive directions of the excitation angles θ may be different from each other. C_prop The maximum values ​​in the negative direction may be different from each other. Alternatively, in both cases, the excitation angle θ C_prop Both the maximum positive value and the maximum negative value may be different from each other.

[0249] For example, the configurations of the first and second envelopes in both excitation angle variable resonators are the sixth configuration as described above, such as the first elastic wave resonator 31A and the second elastic wave resonator 41A shown in FIG. 28, and the excitation angle θ C_prop In this case, the crossing angle θ C1_AP The absolute values ​​of are different. Similarly, the crossing angle θ C2_AP The absolute values ​​of are also different from each other.

[0250] In the first to fourth embodiments, the elastic wave device has two elastic wave resonators as the multiple elastic wave resonators. However, the elastic wave device may have at least three elastic wave resonators as the multiple elastic wave resonators. This example will be described below.

[0251] FIG. 30 is a schematic plan view of an elastic wave device according to a fifth preferred embodiment of the present invention.

[0252] This embodiment differs from the third embodiment in that elastic wave device 51 includes third elastic wave resonator 51C, which is an excitation angle variable resonator. Except for the above, elastic wave device 51 of this embodiment has a similar configuration to elastic wave device 31 of the third embodiment. Similarly to the third embodiment, elastic wave device 51 includes first elastic wave resonator 31A and second elastic wave resonator 41C. Elastic wave device 51 includes three excitation angle variable resonators.

[0253] The first acoustic wave resonator 31A, the second acoustic wave resonator 41C, and the third acoustic wave resonator 51C are connected in series to one another in this order.

[0254] The third acoustic wave resonator 51C has a similar configuration to the second acoustic wave resonator 41C. However, the second acoustic wave resonator 41C and the third acoustic wave resonator 51C have different electrode finger curvatures and bending directions. In the second acoustic wave resonator 41C, the electrode fingers are bent to be convex in the left direction in FIG. 30. On the other hand, in the third acoustic wave resonator 51C, the electrode fingers are bent to be convex in the right direction in FIG. 30.

[0255] The phase characteristics were compared between an elastic wave device having the configuration of this preferred embodiment and an elastic wave device of a comparative example shown in Fig. 6. The results of the first preferred embodiment are also shown. The design parameters of the comparative first preferred embodiment and the comparative example are similar to those of the comparative first preferred embodiment and the comparative example shown in Fig. 23.

[0256] The design parameters of an acoustic wave resonator having the configuration of first acoustic wave resonator 31A in this preferred embodiment are similar to those of the third preferred embodiment for comparison shown in FIG. 23, except for the crossing angle.

[0257] Crossing angle θ C1_AP : 7.5° Crossing angle θ C2_AP : -7.5°

[0258] The design parameters of the elastic wave resonator having the configuration of the second elastic wave resonator 41C in this embodiment are the same as those of the third embodiment for comparison shown in FIG. 23, except for the first envelope excitation angle and the second envelope excitation angle.

[0259] First envelope excitation angle: θ C_AP1_1 = 13.5°, θ C_AP1_2 = 9°, θ C_AP1_3 = 16.5°, θ C_AP1_4 = 9°, θ C_AP1_5 = 16°, θ C_AP1_6 =9° Second envelope excitation angle: θ C_AP2_1 = 10°, θ C_AP2_2 = 16.5°, θ C_AP2_3 = 10°, θ C_AP2_4 = 17°, θ C_AP2_5 = 9.5°, θ C_AP2_6 =16°

[0260] The design parameters of the elastic wave resonator having the configuration of the third elastic wave resonator 51C in this embodiment are similar to the design parameters of the elastic wave resonator having the configuration of the second elastic wave resonator 41C in the third embodiment for comparison shown in Figure 23.

[0261] FIG. 31 is a diagram showing phase characteristics near a frequency at which spurious waves are generated in the first embodiment, the fifth embodiment, and a comparative example.

[0262] 31, it can be seen that the first embodiment is able to suppress Rayleigh waves as unwanted waves more effectively than the comparative example. Furthermore, it can be seen that the fifth embodiment is able to suppress Rayleigh waves even more effectively. Although not shown, in the fifth embodiment, transverse modes can also be suppressed in all of the first acoustic wave resonator 31A, the second acoustic wave resonator 41C, and the third acoustic wave resonator 51C. Thus, the transverse modes can be effectively suppressed in the entire acoustic wave device 51.

[0263] As in the fifth embodiment, at least three of the multiple acoustic wave resonators may be excitation angle variable resonators. Preferably, the at least three excitation angle variable resonators have electrode fingers with different shapes in a plan view. In the fifth embodiment, the first acoustic wave resonator 31A and the other acoustic wave resonators have different configurations of crossing regions, so that the electrode fingers have different shapes in a plan view. The second acoustic wave resonator 41C and the third acoustic wave resonator 51C have electrode fingers with different curvatures, so that the electrode fingers have different shapes in a plan view. This makes it possible to more reliably suppress unwanted waves outside the band as a whole acoustic wave device.

[0264] However, for example, the second acoustic wave resonator 41C and the third acoustic wave resonator 51C may have different duty ratios, and thus may have different shapes of electrode fingers. An example of this is as follows. The excitation angle θ of the second acoustic wave resonator 41C is C_prop Where the excitation angle θ of the third acoustic wave resonator 51C is 0°, the duty ratio is 0.626. C_prop Where the angle is 0°, the duty ratio is 0.5.

[0265] The configuration of the crossing region of the excitation angle changing resonator in the elastic wave device and the configuration of the first and second envelopes are not particularly limited. For example, in a modification of the fifth embodiment shown in FIG. 32, the crossing region of a third elastic wave resonator 51D has the third configuration. That is, the electrode fingers of the third elastic wave resonator 51D have a shape bent at a plurality of nodes in a plan view. In this modification, the first elastic wave resonator 31A and the second elastic wave resonator 41C have the same configuration as those of the fifth embodiment.

[0266] In this modified example, like the fifth embodiment, it is possible to suppress unnecessary waves and transverse modes outside the band.

[0267] However, the layered structure of the piezoelectric substrate is not limited to the configuration shown in Fig. 4. According to the sixth embodiment, an example of an acoustic wave device having a piezoelectric substrate different from that of the first embodiment is shown.

[0268] FIG. 33 is a schematic cross-sectional front view of an elastic wave device according to a sixth preferred embodiment of the present invention.

[0269] This embodiment differs from the first embodiment in the layered structure of piezoelectric substrate 62. A first IDT electrode 18A is shown in Fig. 33. Although not shown, a second IDT electrode 18B similar to that of the first embodiment is also provided on piezoelectric substrate 62. Except for the above points, the elastic wave device of this embodiment has a similar configuration to elastic wave device 1 of the first embodiment.

[0270] The piezoelectric substrate 62 has a support substrate 4, an intermediate layer 65, and a piezoelectric layer 6. The intermediate layer 65 is provided on the support substrate 4. The piezoelectric layer 6 is provided on the intermediate layer 65. In this embodiment, the intermediate layer 65 has a frame-like shape. That is, the intermediate layer 65 has a through hole. The support substrate 4 closes one end of the through hole of the intermediate layer 65. The piezoelectric layer 6 closes the other end of the through hole of the intermediate layer 65. This forms a hollow portion 62c in the piezoelectric substrate 62. A part of the piezoelectric layer 6 and a part of the support substrate 4 face each other with the hollow portion 62c in between.

[0271] In this embodiment, the main mode can be reflected toward the piezoelectric layer 6. Therefore, the energy of the elastic wave can be effectively confined to the piezoelectric layer 6. In addition, as in the first embodiment, unnecessary waves outside the band can be suppressed.

[0272] The following describes a first and a second modified example of the sixth embodiment, which differ from the sixth embodiment only in the laminated structure of the piezoelectric substrate. In the first and the second modified examples, as in the sixth embodiment, it is possible to suppress unnecessary waves outside the band and to effectively confine the energy of the elastic waves on the piezoelectric layer 6 side.

[0273] 34, a piezoelectric substrate 62A has a support substrate 4, an acoustic reflection film 67, an intermediate layer 65A, and a piezoelectric layer 6. The acoustic reflection film 67 is provided on the support substrate 4. The intermediate layer 65A is provided on the acoustic reflection film 67. The piezoelectric layer 6 is provided on the intermediate layer 65A. The intermediate layer 65A is a low acoustic velocity film.

[0274] The acoustic reflection film 67 is a laminate of a plurality of acoustic impedance layers. Specifically, the acoustic reflection film 67 has a plurality of low acoustic impedance layers and a plurality of high acoustic impedance layers. The high acoustic impedance layers are layers with relatively high acoustic impedance. More specifically, the plurality of high acoustic impedance layers of the acoustic reflection film 67 are a high acoustic impedance layer 67a, a high acoustic impedance layer 67c, and a high acoustic impedance layer 67e. On the other hand, the low acoustic impedance layers are layers with relatively low acoustic impedance. More specifically, the plurality of low acoustic impedance layers of the acoustic reflection film 67 are a low acoustic impedance layer 67b and a low acoustic impedance layer 67d. The low acoustic impedance layers and the high acoustic impedance layers are alternately laminated. The high acoustic impedance layer 67a is the layer located closest to the piezoelectric layer 6 in the acoustic reflection film 67.

[0275] The acoustic reflection film 67 has two low acoustic impedance layers and three high acoustic impedance layers, although it is sufficient that the acoustic reflection film 67 has at least one low acoustic impedance layer and one high acoustic impedance layer.

[0276] The low acoustic impedance layer may be made of, for example, silicon oxide or aluminum. The high acoustic impedance layer may be made of, for example, a metal such as platinum or tungsten, or a dielectric such as aluminum nitride or silicon nitride. The material of the intermediate layer 65A may be the same as that of the low acoustic impedance layer.

[0277] In the second modified example shown in FIG. 35, a piezoelectric substrate 62B has a support substrate 64 and a piezoelectric layer 6. The piezoelectric layer 6 is provided directly on the support substrate 64. More specifically, the support substrate 64 has a recess. The piezoelectric layer 6 is provided on the support substrate 64 so as to cover the recess. This provides a hollow portion in the piezoelectric substrate 62B. The hollow portion overlaps at least a portion of the first IDT electrode 18A in a plan view.

[0278] FIG. 36 is a schematic cross-sectional front view of an elastic wave device according to a seventh preferred embodiment of the present invention.

[0279] This embodiment differs from the first embodiment in that the first IDT electrode 18A is embedded in the protective film 79. Although not shown, this embodiment also differs from the first embodiment in that the second IDT electrode 18B shown in FIG. 1 is embedded in the protective film 79. Except for the above points, the elastic wave device of this embodiment has a similar configuration to the elastic wave device 1 of the first embodiment.

[0280] Specifically, a protective film 79 is provided on the piezoelectric layer 6 so as to cover the first IDT electrode 18A. The thickness of the protective film 79 is greater than the thickness of the first IDT electrode 18A. The first IDT electrode 18A is embedded in the protective film 79. This makes the first IDT electrode 18A less susceptible to damage. Similarly, the second IDT electrode 18B is also less susceptible to damage.

[0281] The protective film 79 has a first protective layer 79a and a second protective layer 79b. The first IDT electrode 18A and the second IDT electrode 18B are embedded in the first protective layer 79a. The second protective layer 79b is provided on the first protective layer 79a. This allows the protective film 79 to provide a number of effects. Specifically, in this embodiment, silicon oxide is used as the material for the first protective layer 79a. This allows the absolute value of the temperature coefficient of frequency (TCF) of the acoustic wave device to be reduced. This allows the temperature characteristics of the acoustic wave device to be improved. The second protective layer 79b is made of silicon nitride. This allows the moisture resistance of the acoustic wave device to be increased.

[0282] Additionally, in this embodiment, the first IDT electrode 18A and the second IDT electrode 18B are configured and arranged in the same manner as in the first embodiment, thereby making it possible to suppress unnecessary waves outside the band.

[0283] The materials of the first protective layer 79a and the second protective layer 79b are not limited to those mentioned above. The protective film 79 may be a single layer or a laminate of three or more layers.

[0284] FIG. 37 is a schematic cross-sectional front view of an elastic wave device according to an eighth preferred embodiment of the present invention.

[0285] This embodiment differs from the first embodiment in that a first IDT electrode 18A is provided on both the first principal surface 6a and the second principal surface 6b of the piezoelectric layer 6. Although not shown, this embodiment also differs from the first embodiment in that a second IDT electrode 18B shown in FIG. 1 is provided on both the first principal surface 6a and the second principal surface 6b of the piezoelectric layer 6. The first IDT electrode 18A and the second IDT electrode 18B provided on the second principal surface 6b are embedded in the second layer 5b of the intermediate layer 5. Except for the above points, an elastic wave device 81 of this embodiment has a similar configuration to the elastic wave device 1 of the first embodiment.

[0286] A first IDT electrode 18A provided on the first principal surface 6a of the piezoelectric layer 6 and a second IDT electrode 18B provided on the second principal surface 6b face each other with the piezoelectric layer 6 in between. A second IDT electrode 18B provided on the first principal surface 6a of the piezoelectric layer 6 and a second IDT electrode 18B provided on the second principal surface 6b face each other with the piezoelectric layer 6 in between.

[0287] In an elastic wave device 81 of this preferred embodiment, a first IDT electrode 18A and a second IDT electrode 18B are configured on a first principal surface 6a in the same manner as in the first preferred embodiment. The first IDT electrode 18A and the second IDT electrode 18B are connected to each other without passing through a functional electrode of another elastic wave resonator. The same is true on a second principal surface 6b. This makes it possible to suppress unwanted waves outside the band, as in the first preferred embodiment.

[0288] The first IDT electrodes 18A provided on the first and second principal surfaces 6a and 6b of the piezoelectric layer 6 may have different design parameters, for example. The second IDT electrodes 18B provided on the first and second principal surfaces 6a and 6b may have different design parameters, for example.

[0289] The following describes first to third modified examples of the eighth embodiment, which differ from the eighth embodiment only in at least one of the configuration of the electrodes provided on the second main surface of the piezoelectric layer and the laminated structure of the piezoelectric substrate. In the first to third modified examples, as in the eighth embodiment, unwanted waves outside the band can be suppressed.

[0290] In the first modified example shown in Fig. 38, a piezoelectric substrate 62 is configured similarly to the sixth embodiment. Specifically, the piezoelectric substrate 62 has a support substrate 4, an intermediate layer 65, and a piezoelectric layer 6. A first IDT electrode 18A provided on a second principal surface 6b of the piezoelectric layer 6 is located within a hollow portion 62c. Although not shown, a second IDT electrode 18B provided on the second principal surface 6b is also located within the hollow portion 62c.

[0291] 39, a plate-shaped electrode 88 is provided on the second main surface 6b of the piezoelectric layer 6. The first IDT electrode 18A and the electrode 88 face each other with the piezoelectric layer 6 in between. Another electrode 88 is also provided on the second main surface 6b so as to face the second IDT electrode 18B. Each electrode 88 is embedded in the second layer 5b.

[0292] 40, the piezoelectric substrate 62 is configured similarly to the first modified example, and an electrode 88 similar to that of the second modified example is provided on the second main surface 6b of the piezoelectric layer 6. The electrode 88 is located within the hollow portion 62c.

[0293] In the sixth to eighth embodiments and their respective modifications, examples have been shown in which the first IDT electrode and the second IDT electrode have the same configuration and arrangement as in the first embodiment. However, the piezoelectric substrates of the sixth to eighth embodiments and their respective modifications can also be employed in cases in which the configuration and arrangement of the multiple IDT electrodes are the configuration and arrangement of the present invention other than the first embodiment.

[0294] Examples of configurations of the elastic wave device according to the present invention will be described below.

[0295] <1> An elastic wave device for use in a filter device, comprising: a piezoelectric substrate having a piezoelectric layer; and a plurality of elastic wave resonators each having an IDT electrode provided on the piezoelectric substrate and having a plurality of electrode fingers, at least one of the plurality of elastic wave resonators being an excitation angle variable resonator, the piezoelectric layer having a propagation axis, the plurality of electrode fingers being curved, and the excitation direction of an elastic wave in any portion of any electrode finger among the plurality of electrode fingers in the excitation angle variable resonator being any one of first to third directions, the first direction being perpendicular to a direction in which the electrode fingers extend. the second direction is a direction connecting the electrode finger and the electrode finger adjacent to the electrode finger at the shortest distance, and the third direction is a direction of an electric field vector generated between the electrode finger and the electrode finger adjacent to the electrode finger, and in the excitation angle variable resonator, when an angle between the excitation direction and a direction in which the propagation axis extends is defined as an excitation angle, the excitation angle is not uniform in the IDT electrode, the multiple elastic wave resonators are connected to each other in series or in parallel, no other elements are connected between the multiple elastic wave resonators, and a circuit of the filter device is not branched between the multiple elastic wave resonators.

[0296] <2> At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, and the shapes of the electrode fingers in a plan view of the at least two excitation angle variable resonators are different from each other. <1> The acoustic wave device according to claim 1 .

[0297] <3> the plurality of elastic wave resonators include at least three of the elastic wave resonators, at least three of the plurality of elastic wave resonators are the excitation angle variable resonators, and shapes of the electrode fingers in a plan view are different from each other among the at least three excitation angle variable resonators. <2> The acoustic wave device according to claim 1 .

[0298] <4> In each of the at least two excitation angle variable resonators, a duty ratio is constant at least in a portion where the excitation angle is 0°, and the duty ratios in the portion where the excitation angle is 0° are different between the at least two excitation angle variable resonators. <2> or <3> The acoustic wave device according to claim 1 .

[0299] <5> In each of the at least two excitation angle variable resonators, an electrode finger pitch is constant at least in a portion where the excitation angle is 0°, and the electrode finger pitches in the portion where the excitation angle is 0° are different between the at least two excitation angle variable resonators. <2> ~ <4> 13. The acoustic wave device according to claim 12,

[0300] <6> in each of the at least two excitation angle changing resonators, the shape of the plurality of electrode fingers is curved in a plan view, and when a direction in which the curved portion of the electrode fingers is convex in a direction in which the plurality of electrode fingers are arranged is defined as an outward direction and a direction in which the curved portion of the electrode fingers is concave in a direction in which the plurality of electrode fingers are arranged is defined as an inward direction, curvatures of at least one of the electrode fingers furthest in the outward direction and the electrode fingers furthest in the inward direction of the at least two excitation angle changing resonators are different from each other; <2> ~ <5> 13. The acoustic wave device according to claim 12,

[0301] <7> At least two of the excitation angle variable resonators have different excitation angle ranges. <2> ~ <6> 13. The acoustic wave device according to claim 12,

[0302] <8> The plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips of the tips of the plurality of second electrode fingers is a first envelope, a virtual line formed by connecting the tips of the tips of the plurality of first electrode fingers is a second envelope, a region in the IDT electrode between the first envelope and the second envelope is an intersection region, and a portion of the first electrode finger located on the first envelope is included. a portion of the second electrode finger adjacent to the tip end of any of the second electrode fingers is an adjacent portion of the first electrode finger, the portion of the second electrode finger located on the second envelope curve is included, and the portion of the second electrode finger adjacent to the tip end of any of the first electrode fingers is an adjacent portion of the second electrode finger, and a configuration of the crossing region of at least one of the excitation angle changing resonators is any of first to third configurations, and the first configuration is such that the shapes of the first electrode fingers and the second electrode fingers in a plan view are an arc or an ellipse. the second configuration is a configuration in which the shapes of the plurality of first electrode fingers and the plurality of second electrode fingers in a plan view are curved, the curvature of each of the first electrode fingers and the second electrode fingers is not constant, and the curvature is different between the tip portions located on the first envelope side, between the adjacent portions, or between the tip portion and the adjacent portion, in at least one pair of electrode fingers among the plurality of first electrode fingers and the plurality of second electrode fingers; and the third configuration is a configuration in which, in the intersection region, the electrode electrode includes a plurality of parallel regions in which the plurality of first electrode fingers and the plurality of second electrode fingers extend in parallel, and a non-parallel region in which the directions in which the plurality of first electrode fingers and the plurality of second electrode fingers extend cross each other, the parallel regions and the non-parallel regions are alternately arranged in at least a part of the crossing regions, the plurality of first electrode fingers and the plurality of second electrode fingers each extend linearly in the plurality of parallel regions and the non-parallel regions, and are bent at the boundaries between the parallel regions and the non-parallel regions; <1> ~ <7> 13. The acoustic wave device according to claim 12,

[0303] <9> at least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode interposed therebetween, and has a pair of reflectors each having a plurality of reflector electrode fingers, a configuration in the crossing region of the at least one excitation angle changing resonator is one of the first configuration and the second configuration, and a shape of the plurality of reflector electrode fingers in a plan view includes a curved shape; <8> The acoustic wave device according to claim 1 .

[0304] <10> At least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode interposed therebetween, and has a pair of reflectors each having a plurality of reflector electrode fingers, and a configuration in the crossing region of the at least one excitation angle changing resonator is the third configuration, and a shape of the plurality of reflector electrode fingers in a plan view includes a shape bent at a plurality of nodes. <8> The acoustic wave device according to claim 1 .

[0305] <11> At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, and the configurations of the crossing regions of the at least two excitation angle variable resonators are any one of the first to third configurations different from each other. <8> ~ <10> 13. The acoustic wave device according to claim 12,

[0306] <12> the plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting tips at the tips of the plurality of second electrode fingers is a first envelope, a virtual line formed by connecting tips at the tips of the plurality of first electrode fingers is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is an intersection region, and the extension directions of both the first envelope and the second envelope change, at least A configuration in which both the first envelope curve and the second envelope curve have a shape having one bent portion is defined as a fourth configuration, a configuration in which both the first envelope curve and the second envelope curve are linear and extend in parallel to each other is defined as a fifth configuration, and a configuration in which both the first envelope curve and the second envelope curve are linear and the extending direction of the first envelope curve and the extending direction of the second envelope curve cross each other is defined as a sixth configuration. In this case, the configuration of the first envelope curve and the second envelope curve of at least one of the excitation angle changing resonators is any one of the fourth to sixth configurations. <1> ~ <11> 13. The acoustic wave device according to claim 12,

[0307] <13> At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, and the first envelope curve and the second envelope curve of the at least two excitation angle variable resonators have configurations different from each other among fourth to sixth configurations. <12> The acoustic wave device according to claim 1 .

[0308] <14> In all of the excitation angle variable resonators, the configuration of the first envelope curve and the second envelope curve is the fourth configuration. <12> The acoustic wave device according to claim 1 .

[0309] <15> In all of the excitation angle variable resonators, the configuration of the first envelope curve and the second envelope curve is the fifth configuration. <12> The acoustic wave device according to claim 1 .

[0310] <16> In all of the excitation angle variable resonators, the configuration of the first envelope curve and the second envelope curve is the sixth configuration. <12> The acoustic wave device according to claim 1 .

[0311] <17> all of the elastic wave resonators are excitation angle variable resonators, and shapes of the electrode fingers in a plan view are different among all of the excitation angle variable resonators; <1> ~ <16> 13. The acoustic wave device according to claim 12,

[0312] <18> at least one of the plurality of elastic wave resonators is not the excitation angle variable type resonator, and the plurality of electrode fingers of the elastic wave resonator that is not the excitation angle variable type resonator have a linear shape in a plan view; <1> ~ <16> 13. The acoustic wave device according to claim 12,

[0313] <19> In the elastic wave resonator that is not the excitation angle variable resonator, the piezoelectric layer has a propagation axis, the plurality of electrode fingers in the IDT electrode of the elastic wave resonator include a plurality of third electrode fingers and a plurality of fourth electrode fingers that are interdigitated with each other, and when an imaginary line formed by connecting the tips of the tips of the plurality of fourth electrode fingers is defined as a third envelope and an imaginary line formed by connecting the tips of the tips of the plurality of third electrode fingers is defined as a fourth envelope, the third envelope and the fourth envelope are inclined with respect to the propagation axis. <18> The acoustic wave device according to claim 1 .

[0314] <20> At least one of an electrode finger pitch and a duty ratio is constant in a portion of the IDT electrode of at least one of the excitation angle variable resonators where the excitation angle is the same. <1> ~ <19> 13. The acoustic wave device according to claim 12,

[0315] <21> the plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips of the plurality of second electrode fingers at their tips is a first envelope, a virtual line formed by connecting the tips of the plurality of first electrode fingers at their tips is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is a crossing region, and a resonant frequency or an anti-resonant frequency is approximately the same in the crossing region of at least one of the excitation angle variable resonators; <1> ~ <20> 13. The acoustic wave device according to claim 12,

[0316] <22> at least two of the plurality of elastic wave resonators are the excitation angle variable resonators, the at least two excitation angle variable resonators have substantially the same resonance frequency in the respective crossing regions, and when a resonance frequency of a portion in the crossing region where the excitation angle is 0° is taken as a reference resonance frequency, a relationship is established between the at least two excitation angle variable resonators in which a difference in the reference resonance frequency between the two excitation angle variable resonators having substantially the same resonance frequency in the crossing region is 2% or less with respect to the reference resonance frequency of either of the two excitation angle variable resonators. <21> The acoustic wave device according to claim 1 .

[0317] <23> at least one of the plurality of elastic wave resonators is not the excitation angle-variable resonator, and at least one of the excitation angle-variable resonators has a substantially equal resonance frequency in the crossing region, and when a resonance frequency of a portion of the crossing region where the excitation angle is 0° is taken as a reference resonance frequency, a difference between the reference resonance frequency of the excitation angle-variable resonator whose resonance frequency is substantially equal in the crossing region and the resonance frequency of the elastic wave resonator that is not the excitation angle-variable resonator is 2% or less with respect to both the reference resonance frequency and the resonance frequency. <21> The acoustic wave device according to claim 1 .

[0318] <24> at least two of the plurality of elastic wave resonators are the excitation angle variable resonators, the at least two excitation angle variable resonators have substantially the same resonance frequency in the respective crossing regions, and when a resonance frequency of a portion in the crossing region where the excitation angle is 0° is taken as a reference resonance frequency, a relationship is established between the at least two excitation angle variable resonators in which a difference in the reference resonance frequency between the two excitation angle variable resonators having substantially the same resonance frequency in the crossing region is greater than 2% with respect to the reference resonance frequency of either of the two excitation angle variable resonators. <21> The acoustic wave device according to claim 1 .

[0319] <25> at least one of the plurality of elastic wave resonators is not the excitation angle-variable resonator, and at least one of the excitation angle-variable resonators has a resonance frequency that is approximately the same in the crossing region, and when a resonance frequency of a portion in the crossing region where the excitation angle is 0° is taken as a reference resonance frequency, a difference between the reference resonance frequency of the excitation angle-variable resonator whose resonance frequency is approximately the same in the crossing region and the resonance frequency of the elastic wave resonator that is not the excitation angle-variable resonator is larger than 2% with respect to both the reference resonance frequency and the resonance frequency. <21> The acoustic wave device according to claim 1 .

[0320] <26> the plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips of the plurality of second electrode fingers at their tips is a first envelope, and a virtual line formed by connecting the tips of the plurality of first electrode fingers at their tips is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is an intersection region, the intersection region has a first edge region including the first envelope, a second edge region including the second envelope, and a central region sandwiched between the first edge region and the second edge region, and in at least one of the excitation angle variable resonators, a low acoustic velocity region is formed in at least a part of at least one of the first edge region and the second edge region, in which the acoustic velocity is lower than the acoustic velocity in the central region. <1> ~ <25> 13. The acoustic wave device according to claim 12,

[0321] <27> In at least one of the first edge region and the second edge region, at least one of the electrode fingers has a wide portion that is wider than a width in the central region, thereby forming the low acoustic velocity region. <26> The acoustic wave device according to claim 1 .

[0322] <28> a mass-adding film is further provided in at least one of the first edge region and the second edge region so as to overlap at least one of the plurality of first electrode fingers and the plurality of second electrode fingers when viewed in a plan view, and the low acoustic velocity region is configured by providing the mass-adding film. <26> or <27> The acoustic wave device according to claim 1 .

[0323] <29> At least one of the electrode fingers in the first edge region and the second edge region has a thickness greater than a thickness in the central region, thereby forming the low acoustic velocity region. <26> ~ <28> 13. The acoustic wave device according to claim 12,

[0324] <30> The low sound velocity region is configured throughout both the first edge region and the second edge region. <26> ~ <29> 13. The acoustic wave device according to claim 12,

[0325] <31> The piezoelectric substrate has a support substrate, and the piezoelectric layer is provided on the support substrate. <1> ~ <30> 13. The acoustic wave device according to claim 12,

[0326] <32> The piezoelectric substrate has an intermediate layer provided between the support substrate and the piezoelectric layer. <31> The acoustic wave device according to claim 1 .

[0327] <33> a hollow portion is formed in the piezoelectric substrate, and a part of the support substrate and a part of the piezoelectric layer face each other with the hollow portion interposed therebetween; <32> The acoustic wave device according to claim 1 .

[0328] <34> The piezoelectric substrate is composed of only the piezoelectric layer. <1> ~ <30> 13. The acoustic wave device according to claim 12, [Explanation of symbols]

[0329] 1. Elastic wave device 1A, 1B...First and second elastic wave resonators 1C, 1D, 1J...First acoustic wave resonator 2...Piezoelectric substrate 3...Support member 4…Support substrate 5. Middle class 5a, 5b...First and second layers 6...Piezoelectric layer 6a, 6b...First and second principal surfaces 7A…Input terminal 7B…Output terminal 8...Dielectric film 9A~9H…Reflector 9a, 9b...Reflector busbar 9c…Reflector electrode finger 9d, 9e…Reflector busbar 9f…Reflector electrode finger 10...Filter device 12A…First offset electrode 12B…Third offset electrode 12D, 12I...First offset electrode 13A…Second offset electrode 13B…Fourth offset electrode 13D, 13I...Second offset electrodes 14A, 15A...1st and 2nd bus bars 16A…First electrode finger 16B…Third electrode finger 16C, 16D, 16F to 16H: First electrode finger 16a, 16b…Wide section 17A…Second electrode finger 17B…4th electrode finger 17C, 17D, 17F~17H...Second electrode finger 17a, 17b…Wide section 18A, 18B: First and second IDT electrodes 18C~18J…First IDT electrode 19... Mass-added membrane 21...Elastic wave device 21B...Second acoustic wave resonator 28B…Second IDT electrode 31...Elastic wave device 31A, 31C...First acoustic wave resonator 31D...Second acoustic wave resonator 31J...first acoustic wave resonator 41A, 41C, 41J...Second acoustic wave resonator 51...Elastic wave device 51C, 51D...Third acoustic wave resonator 62, 62A, 62B...Piezoelectric substrate 62c…Hollow part 64…Support substrate 65,65A…middle layer 67…Acoustic reflective film 67a…High acoustic impedance layer 67b…Low acoustic impedance layer 67c…High acoustic impedance layer 67d…Low acoustic impedance layer 67e…High acoustic impedance layer 79...Protective film 79a, 79b...First and second protective layers 81...Elastic wave device 88...Electrode 101A, 101B...first and second elastic wave resonators A…Parallel area B…Non-parallel region D…Node E1, E1C…First envelope E2, E2C: Second envelope E3, E4: 3rd and 4th envelopes F…Central area H1, H2: First and second edge areas J...Cross area K1, K2: First and second curve regions P...parallel arm P1, P2: Parallel arm resonator section S: Series arm S2, S3: Series arm resonator section V1, V2: Bend W1~W3: 1st to 3rd regions

Claims

1. An acoustic wave device for use in a filter device, a piezoelectric substrate having a piezoelectric layer; and a plurality of elastic wave resonators each having an IDT electrode provided on the piezoelectric substrate and having a plurality of electrode fingers; At least one of the plurality of elastic wave resonators is an excitation angle variable resonator, In the excitation angle changing resonator, the piezoelectric layer has a propagation axis, and the electrode fingers are curved, In the excitation angle changing resonator, an excitation direction of an acoustic wave in an arbitrary portion of an arbitrary electrode finger among the plurality of electrode fingers is any one of first to third directions; the first direction is perpendicular to a direction in which the electrode fingers extend, the second direction is a direction that connects the electrode finger and the shortest distance between the electrode finger and the adjacent electrode finger, the third direction is a direction of an electric field vector generated between the electrode finger and the electrode finger adjacent to the electrode finger, In the excitation angle variable resonator, when an angle between the excitation direction and a direction in which the propagation axis extends is defined as an excitation angle, the excitation angle is not uniform in the IDT electrode, An elastic wave device, wherein the multiple elastic wave resonators are connected to each other in series or parallel, no other elements are connected between the multiple elastic wave resonators, and the circuit of the filter device does not branch between the multiple elastic wave resonators.

2. At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, The acoustic wave device according to claim 1 , wherein the electrode fingers of at least two of the excitation angle changing resonators have different shapes in a plan view.

3. the plurality of elastic wave resonators includes at least three of the elastic wave resonators, At least three of the plurality of elastic wave resonators are the excitation angle variable resonators, The acoustic wave device according to claim 2 , wherein the electrode fingers of at least three of the excitation angle changing resonators have different shapes in a plan view.

4. 3. The elastic wave device according to claim 2, wherein the duty ratio of each of the at least two excitation angle variable resonators is constant at least in the portion where the excitation angle is 0°, and the duty ratios of the at least two excitation angle variable resonators are different from each other in the portion where the excitation angle is 0°.

5. 3. The elastic wave device according to claim 2, wherein in each of the at least two excitation angle variable resonators, the electrode finger pitch is constant at least in the portion where the excitation angle is 0°, and the electrode finger pitches in the portion where the excitation angle is 0° are different between the at least two excitation angle variable resonators.

6. 3. The elastic wave device according to claim 2, wherein in each of the at least two excitation angle changing resonators, the multiple electrode fingers have a curved shape in a planar view, and when a direction in which the curved portion of the electrode fingers is convex in a direction in which the multiple electrode fingers are arranged is defined as an outward direction and a direction in which the curved portion of the electrode fingers is concave in a direction in which the multiple electrode fingers are arranged is defined as an inward direction, the curvatures of at least one of the electrode fingers furthest in the outward direction and the electrode fingers furthest in the inward direction of the at least two excitation angle changing resonators are different from each other.

7. The acoustic wave device according to claim 2 , wherein the ranges of the excitation angles of at least two of the excitation angle variable resonators are different from each other.

8. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; a portion of the first electrode finger including a portion located on the first envelope and adjacent to the tip portion of any of the second electrode fingers is an adjacent portion of the first electrode finger, and a portion of the second electrode finger including a portion located on the second envelope and adjacent to the tip portion of any of the first electrode fingers is an adjacent portion of the second electrode finger, At least one of the excitation angle changing resonators has a configuration in the crossover region that is any one of first to third configurations; the first configuration is a configuration in which the shapes of the plurality of first electrode fingers and the plurality of second electrode fingers in a plan view include a shape of a circular arc or an elliptical arc; the second configuration is a configuration in which the shapes of the plurality of first electrode fingers and the plurality of second electrode fingers are curved in a plan view, the curvature of each of the first electrode fingers and the second electrode fingers is not constant, and the curvature is different between the tip portions located on the first envelope side, between the adjacent portions, or between the tip portion and the adjacent portion, in at least one pair of electrode fingers among the plurality of first electrode fingers and the plurality of second electrode fingers; 2. The elastic wave device according to claim 1, wherein the third configuration includes, in the intersection region, a plurality of parallel regions in which the plurality of first electrode fingers and the plurality of second electrode fingers extend in parallel, and a non-parallel region in which the extension directions of the plurality of first electrode fingers and the plurality of second electrode fingers intersect with each other, the parallel regions and the non-parallel regions are alternately arranged in at least a part of the intersection region, and the plurality of first electrode fingers and the plurality of second electrode fingers each extend linearly in the plurality of parallel regions and the non-parallel regions, and are bent at the boundary between the parallel regions and the non-parallel regions.

9. At least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode therebetween, and includes a pair of reflectors each having a plurality of reflector electrode fingers; 9. The elastic wave device according to claim 8, wherein a configuration in the crossing region of at least one of the excitation angle changing resonators is one of the first configuration and the second configuration, and a shape of the plurality of reflector electrode fingers in a planar view includes a curved shape.

10. At least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode therebetween, and includes a pair of reflectors each having a plurality of reflector electrode fingers; 9. The elastic wave device according to claim 8, wherein a configuration in the intersection region of at least one of the excitation angle changing resonators is the third configuration, and a shape of the plurality of reflector electrode fingers in a planar view includes a shape bent at a plurality of nodes.

11. At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, 9. The acoustic wave device according to claim 8, wherein the crossing regions of the at least two excitation angle changing resonators have any one of the first to third configurations that are different from each other.

12. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; 2. The elastic wave device according to claim 1, wherein the configuration of the first envelope and the second envelope of at least one of the excitation angle changing resonators is any one of the fourth to sixth configurations, where a fourth configuration is a configuration in which both the first envelope and the second envelope have a shape having at least one bent portion in which the direction of extension changes, a fifth configuration is a configuration in which both the first envelope and the second envelope are linear and extend in parallel, and a sixth configuration is a configuration in which both the first envelope and the second envelope are linear and the extension direction of the first envelope and the extension direction of the second envelope intersect.

13. At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, The elastic wave device according to claim 12, wherein the first envelope and the second envelope of at least two of the excitation angle changing resonators have mutually different configurations selected from among fourth to sixth configurations.

14. The elastic wave device according to claim 12 , wherein the first envelope and the second envelope have the fourth configuration in all of the excitation angle changing resonators.

15. The elastic wave device according to claim 12 , wherein the first envelope and the second envelope have the fifth configuration in all of the excitation angle changing resonators.

16. The elastic wave device according to claim 12 , wherein the first envelope and the second envelope have the sixth configuration in all of the excitation angle changing resonators.

17. all of the elastic wave resonators are excitation angle variable resonators, The acoustic wave device according to claim 1 , wherein the electrode fingers of all of the excitation angle changing resonators have different shapes in a plan view.

18. At least one of the plurality of elastic wave resonators is not the excitation angle variable resonator, The acoustic wave device according to claim 1 , wherein the electrode fingers of the acoustic wave resonator that is not the excitation angle variable resonator have a linear shape in a plan view.

19. In the elastic wave resonator that is not an excitation angle variable resonator, the piezoelectric layer has a propagation axis, and the plurality of electrode fingers in the IDT electrode of the elastic wave resonator include a plurality of third electrode fingers and a plurality of fourth electrode fingers that are interdigitated with each other, 19. The elastic wave device of claim 18, wherein when a virtual line formed by connecting the tips at the tip portions of the plurality of fourth electrode fingers is defined as a third envelope and a virtual line formed by connecting the tips at the tip portions of the plurality of third electrode fingers is defined as a fourth envelope, the third envelope and the fourth envelope are inclined with respect to the propagation axis.

20. 2 . The acoustic wave device according to claim 1 , wherein at least one of an electrode finger pitch and a duty ratio is constant in a portion of the IDT electrode of at least one of the excitation angle variable resonators, where the excitation angle is the same.

21. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; The acoustic wave device according to claim 1 , wherein at least one of the excitation angle changing resonators has a resonant frequency or an anti-resonant frequency that is substantially the same in the crossing region.

22. At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, The resonant frequencies of the at least two excitation angle-changing resonators are substantially the same in the crossing regions, 22. The elastic wave device according to claim 21, wherein when a resonant frequency of a portion in the crossing region where the excitation angle is 0° is defined as a reference resonant frequency, a relationship is established between at least two of the excitation angle-variable resonators in which a difference in the reference resonant frequency between two excitation angle-variable resonators whose resonant frequencies are approximately the same in the crossing region is 2% or less with respect to the reference resonant frequency of either of the two excitation angle-variable resonators.

23. At least one of the plurality of elastic wave resonators is not the excitation angle variable resonator, At least one of the excitation angle changing resonators has a substantially equal resonant frequency in the crossing region, 22. The elastic wave device according to claim 21, wherein when a resonant frequency of a portion in the crossing region where the excitation angle is 0° is taken as a reference resonant frequency, a difference between the reference resonant frequency of the excitation angle-variable resonator, whose resonant frequencies are approximately equal in the crossing region, and the resonant frequency of the elastic wave resonator that is not the excitation angle-variable resonator, is 2% or less with respect to both the reference resonant frequency and the resonant frequency, for at least one of the excitation angle-variable resonators and at least one of the elastic wave resonators that is not the excitation angle-variable resonator.

24. At least two of the plurality of elastic wave resonators are the excitation angle variable resonators, The resonant frequencies of the at least two excitation angle-changing resonators are substantially the same in the crossing regions, 22. The elastic wave device according to claim 21, wherein when a resonant frequency of a portion in the crossing region where the excitation angle is 0° is defined as a reference resonant frequency, a relationship is established between at least two of the excitation angle-variable resonators such that a difference in the reference resonant frequency between two excitation angle-variable resonators whose resonant frequencies are approximately the same in the crossing region is greater than 2% with respect to the reference resonant frequency of each of the two excitation angle-variable resonators.

25. At least one of the plurality of elastic wave resonators is not the excitation angle variable resonator, At least one of the excitation angle changing resonators has a substantially equal resonant frequency in the crossing region, 22. The elastic wave device according to claim 21, wherein when a resonant frequency of a portion in the crossing region where the excitation angle is 0° is taken as a reference resonant frequency, a relationship is established in at least one of the excitation angle-variable resonators and at least one of the elastic wave resonators that is not an excitation angle-variable resonator such that a difference between the reference resonant frequency of the excitation angle-variable resonators, whose resonant frequencies are approximately equal in the crossing region, and the resonant frequency of the elastic wave resonators that are not the excitation angle-variable resonators, is greater than 2% with respect to both the reference resonant frequency and the resonant frequency.

26. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; the intersection region has a first edge region including the first envelope curve, a second edge region including the second envelope curve, and a central region sandwiched between the first edge region and the second edge region, 2. The elastic wave device according to claim 1, wherein in at least one of the excitation angle changing resonators, a low acoustic velocity region is formed in at least a portion of at least one of the first edge region and the second edge region, the low acoustic velocity region having a lower acoustic velocity than the acoustic velocity in the central region.

27. 27. The elastic wave device of claim 26, wherein in at least one of the first edge region and the second edge region, at least one of the electrode fingers has a wide portion that is wider than its width in the central region, thereby forming the low acoustic velocity region.

28. a mass-adding film provided in at least one of the first edge region and the second edge region so as to overlap at least one of the first electrode fingers and the second electrode fingers in a plan view; The acoustic wave device according to claim 26 , wherein the low acoustic velocity region is formed by providing the mass addition film.

29. 27. The elastic wave device of claim 26, wherein the low acoustic velocity region is defined by at least one of the first edge region and the second edge region having a thickness greater than a thickness of at least one of the electrode fingers in the central region.

30. The acoustic wave device of claim 26 , wherein the low acoustic velocity region is configured throughout both the first edge region and the second edge region.

31. the piezoelectric substrate has a support substrate; The acoustic wave device according to claim 1 , wherein the piezoelectric layer is provided on the supporting substrate.

32. The acoustic wave device according to claim 31 , wherein the piezoelectric substrate includes an intermediate layer provided between the support substrate and the piezoelectric layer.

33. The acoustic wave device according to claim 32 , wherein the piezoelectric substrate has a hollow portion, and a part of the support substrate and a part of the piezoelectric layer face each other with the hollow portion therebetween.

34. The acoustic wave device according to claim 1 , wherein the piezoelectric substrate consists solely of the piezoelectric layer.

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