Elastic wave device

Abstract

To provide an elastic wave device 10 in which a lateral mode is suppressed more surely without decreasing productivity.SOLUTION: An elastic wave device 10 includes first and second elastic wave resonators 1A, 1B having first and second IDT electrodes 3A, 3B on a piezoelectric substrate 2. In the first and second IDT electrodes, regions where the adjacent electrode fingers are overlapped correspond to first and second intersection regions A1, A2. The first intersection region A1 includes an edge region E1 and an edge region E2 having a central region C1 therebetween. The second intersection region A2 includes an edge region E3 and an edge region E4 having a central region C2 therebetween. The elastic wave device 10 further includes first and second mass addition films 4A and 4B. A thickness of a plurality of electrode fingers of the second IDT electrode is smaller than that of the first IDT electrode. A thickness of the first mass addition film is the same as that of the second mass addition film. A width of the second mass addition film in the electrode fingers of the second IDT electrode is smaller than that of the central region C2.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, acoustic wave devices have been widely used as filters for mobile phones and the like. Patent Document 1 below discloses an example of an acoustic wave device. In this acoustic wave device, an IDT electrode is provided on a piezoelectric substrate. The IDT (Interdigital Transducer) electrode has a central region and a pair of low acoustic velocity regions. The pair of low acoustic velocity regions sandwich the central region in the direction in which the electrode fingers of the IDT electrode extend. A mass-adding film is provided in each of the low acoustic velocity regions. With the above configuration, spurious due to the transverse mode is suppressed.

[0003] In the acoustic wave device described in Patent Document 2 below, an IDT electrode is provided on a piezoelectric layer. The IDT electrode has a central region and a pair of edge regions. The pair of edge regions sandwich the central region in the direction in which the electrode fingers of the IDT electrode extend. The width of the electrode fingers in the edge regions is wider than the width of the electrode fingers in the central region. This configuration suppresses spurious responses due to transverse modes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-092095 A [Patent Document 2] International Publication No. 2021 / 065684 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when an elastic wave device has multiple elastic wave resonators, the resonant frequencies of these elastic wave resonators are often different from one another. In this case, it is necessary to adjust the configuration for suppressing the transverse mode for each elastic wave resonator. This may result in low productivity of the elastic wave device.

[0006] An object of the present invention is to provide an acoustic wave device that can more reliably suppress transverse modes without reducing productivity. [Means for solving the problem]

[0007] An elastic wave device according to the present invention includes a first elastic wave resonator having a piezoelectric substrate and a first IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate, and a second elastic wave resonator sharing the piezoelectric substrate with the first elastic wave resonator and having a second IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate, wherein a region in the first IDT electrode where adjacent electrode fingers overlap when viewed from a direction perpendicular to a direction in which the electrode fingers extend is a first crossing region, the first crossing region having a first central region, and a first edge region and a second edge region sandwiching the first central region in the direction in which the electrode fingers extend, and a second crossing region where adjacent electrode fingers overlap when viewed from a direction perpendicular to the direction in which the electrode fingers extend is a second crossing region, the second crossing region having a first central region and a first edge region and a second edge region. the first IDT electrode includes a first mass adding film provided in at least one of the first edge region and the second edge region and overlapping with the electrode fingers of the first IDT electrode in a planar view; and a second mass adding film provided in at least one of the third edge region and the fourth edge region and overlapping with the electrode fingers of the second IDT electrode in a planar view, wherein a thickness of the electrode fingers of the second IDT electrode is thinner than a thickness of the electrode fingers of the first IDT electrode, a thickness of the first mass adding film is the same as a thickness of the second mass adding film, and a width of a portion of the electrode fingers of the second IDT electrode overlapping with the second mass adding film in a planar view is narrower than a width of the electrode fingers in the second central region. Effect of the Invention

[0008] According to an acoustic wave device according to a preferred embodiment of the present invention, it is possible to provide an acoustic wave device that can more reliably suppress transverse modes without reducing productivity. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an elastic wave device according to a first preferred embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic plan view of a first acoustic wave resonator and a second acoustic wave resonator according to a first embodiment of the present invention. [Diagram 3] 1 is a schematic cross-sectional front view illustrating a pair of electrode fingers of a first acoustic wave resonator and a pair of electrode fingers of a second acoustic wave resonator according to a first preferred embodiment of the present invention. [Figure 4] 2 is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of a first IDT electrode and the vicinity of one electrode finger of a second IDT electrode in the first embodiment of the present invention. FIG. [Diagram 5] 1 is a diagram showing the relationship between the wavelength ratio width W and the thickness ratio TR of the mass-adding film when the magnitude of the ripple caused by the transverse mode is 1 dB or 0.1 dB. [Figure 6] 1 is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of a first IDT electrode and the vicinity of one electrode finger of a second IDT electrode in a first reference example. FIG. [Figure 7] 13 is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of a first IDT electrode and the vicinity of one electrode finger of a second IDT electrode in a second reference example. FIG. [Figure 8] 10 is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of a first IDT electrode and the vicinity of one electrode finger of a second IDT electrode in a modified example of the first embodiment of the present invention. FIG. [Figure 9] 10 is a schematic plan view of a first acoustic wave resonator and a second acoustic wave resonator according to a second embodiment of the present invention. FIG. [Figure 10] 11 is a schematic plan view showing an enlarged view of the vicinity of one electrode finger of a first IDT electrode and the vicinity of one electrode finger of a second IDT electrode according to a second embodiment of the present invention. FIG. [Figure 11] 13 is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of a first IDT electrode and the vicinity of one electrode finger of a second IDT electrode in a modified example of the second embodiment of the present invention. FIG. [Figure 12] 11 is a schematic diagram of an elastic wave device according to a third preferred 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 diagram of an elastic wave device according to a first preferred embodiment of the present invention. Fig. 2 is a schematic plan view of a first elastic wave resonator and a second elastic wave resonator according to the first preferred embodiment. Note that a dielectric film, which will be described later, is omitted in Fig. 2.

[0013] The elastic wave device 10 shown in FIG. 1 is a composite filter device. The elastic wave device 10 includes a first filter device 10A and a second filter device 10B. Specifically, the first filter device 10A and the second filter device 10B are band-pass filters. The first filter device 10A and the second filter device 10B may both be a transmission filter or a reception filter. In this embodiment, the first filter device 10A and the second filter device 10B are connected to different signal potentials.

[0014] However, the elastic wave device 10 may be a multiplexer such as a duplexer. In this case, for example, the input potential side or the output potential side of the first filter device 10A and the input potential side or the output potential side of the second filter device 10B may be commonly connected to a terminal of the same signal potential.

[0015] The pass band of the first filter device 10A and the pass band of the second filter device 10B are different from each other. More specifically, the pass band of the second filter device 10B is located higher than the pass band of the first filter device 10A. The first filter device 10A may be used as, for example, a band-pass filter for a middle band. The second filter device 10B may be used as, for example, a band-pass filter for a high band.

[0016] The first filter device 10A has a first acoustic wave resonator 1A shown in FIG. 2. The second filter device 10B has a second acoustic wave resonator 1B shown in FIG. 2. The resonant frequency of the second acoustic wave resonator 1B is higher than the resonant frequency of the first acoustic wave resonator 1A. Note that in FIG. 2, the first acoustic wave resonator 1A and the second acoustic wave resonator 1B are shown diagrammatically side by side. However, the arrangement of the first acoustic wave resonator 1A and the second acoustic wave resonator 1B is not particularly limited.

[0017] The first acoustic wave resonator 1A and the second acoustic wave resonator 1B share the piezoelectric substrate 2. The piezoelectric substrate 2 is a substrate having piezoelectric properties. In this embodiment, the piezoelectric substrate 2 is a laminated substrate including a piezoelectric layer 16. Note that the piezoelectric substrate 2 may be a substrate made only of a piezoelectric material.

[0018] The first acoustic wave resonator 1A has a first IDT electrode 3A. The first IDT electrode 3A is provided on a piezoelectric substrate 2. In the following description, "provided on the piezoelectric substrate 2" refers to "provided on the piezoelectric layer 16" unless otherwise specified.

[0019] The first IDT electrode 3A has a pair of bus bars and a plurality of electrode fingers. The pair of bus bars is specifically a first bus bar 6A and a second bus bar 7A. The first bus bar 6A and the second bus bar 7A face each other. The plurality of electrode fingers is specifically a plurality of first electrode fingers 8A and a plurality of second electrode fingers 9A. One ends of the plurality of first electrode fingers 8A are connected to the first bus bar 6A. One ends of the plurality of second electrode fingers 9A are connected to the second bus bar 7A. The first electrode fingers 8A and the second electrode fingers 9A are connected to different potentials. The plurality of first electrode fingers 8A and the plurality of second electrode fingers 9A are interdigitated with each other.

[0020] The second acoustic wave resonator 1B has a second IDT electrode 3B. The second IDT electrode 3B is provided on a piezoelectric substrate 2. The second IDT electrode 3B has a pair of bus bars and a plurality of electrode fingers. The pair of bus bars is specifically a third bus bar 6B and a fourth bus bar 7B. The third bus bar 6B and the fourth bus bar 7B face each other. The plurality of electrode fingers is specifically a plurality of third electrode fingers 8B and a plurality of fourth electrode fingers 9B. One ends of the plurality of third electrode fingers 8B are connected to the third bus bar 6B. One ends of the plurality of fourth electrode fingers 9B are connected to the fourth bus bar 7B. The plurality of third electrode fingers 8B and the plurality of fourth electrode fingers 9B are interdigitated with each other.

[0021] 3 is a schematic cross-sectional front view showing a pair of electrode fingers of a first acoustic wave resonator and a pair of electrode fingers of a second acoustic wave resonator according to the first embodiment, in a first edge region and a third edge region described later.

[0022] The thickness of the electrode fingers of second IDT electrode 3B is thinner than the thickness of the electrode fingers of first IDT electrode 3A, which makes it easier to increase the resonant frequency of second acoustic wave resonator 1B and to decrease the resonant frequency of first acoustic wave resonator 1A.

[0023] 2 , the direction in which the first electrode fingers 8A and the second electrode fingers 9A extend is the electrode finger extension direction of the first IDT electrode 3A, and the direction perpendicular to the electrode finger extension direction is the electrode finger orthogonal direction of the first IDT electrode 3A. The direction in which the third electrode fingers 8B and the fourth electrode fingers 9B extend is the electrode finger extension direction of the second IDT electrode 3B, and the direction perpendicular to the electrode finger extension direction is the electrode finger orthogonal direction of the second IDT electrode 3B. However, in this embodiment, the electrode finger extension directions are parallel to each other and the electrode finger orthogonal directions are parallel to each other in the first acoustic wave resonator 1A and the second acoustic wave resonator 1B.

[0024] An AC voltage is applied to the first IDT electrode 3A to excite an acoustic wave. A pair of reflectors 18A and 18B are provided on both sides of the first IDT electrode 3A in the acoustic wave propagation direction on the piezoelectric substrate 2. The first acoustic wave resonator 1A is a surface acoustic wave resonator. The acoustic wave propagation direction of the first IDT electrode 3A is parallel to the electrode finger orthogonal direction.

[0025] An AC voltage is applied to the second IDT electrode 3B to excite an acoustic wave. A pair of reflectors 18C and 18D are provided on both sides of the second IDT electrode 3B in the acoustic wave propagation direction on the piezoelectric substrate 2. The second acoustic wave resonator 1B is a surface acoustic wave resonator. The acoustic wave propagation direction of the second IDT electrode 3B is parallel to the electrode finger orthogonal direction.

[0026] In this embodiment, the first IDT electrode 3A, the second IDT electrode 3B, and each reflector are made of a laminated metal film. Specifically, in these, a Ti layer, an Al layer, and a Ti layer are laminated in this order from the piezoelectric substrate 2 side. However, the materials of the first IDT electrode 3A, the second IDT electrode 3B, and each reflector are not limited to those mentioned above. Alternatively, the first IDT electrode 3A, the second IDT electrode 3B, and each reflector may be made of a single-layer metal film.

[0027] In the first IDT electrode 3A, when viewed from the electrode finger orthogonal direction, a region where adjacent first electrode finger 8A and second electrode finger 9A overlap is the first intersection region A1. The first intersection region A1 has a first central region C1 and a pair of edge regions. Specifically, the pair of edge regions is a first edge region E1 and a second edge region E2. The first edge region E1 and the second edge region E2 face each other with the first central region C1 in between in the electrode finger extension direction. The first edge region E1 is located on the first bus bar 6A side. The second edge region E2 is located on the second bus bar 7A side.

[0028] In the second IDT electrode 3B, when viewed from the electrode finger orthogonal direction, a region where adjacent third electrode finger 8B and fourth electrode finger 9B overlap is the second intersection region A2. The second intersection region A2 has a second central region C2 and a pair of edge regions. Specifically, the pair of edge regions is a third edge region E3 and a fourth edge region E4. The third edge region E3 and the fourth edge region E4 face each other with the second central region C2 in between in the electrode finger extension direction. The third edge region E3 is located on the third bus bar 6B side. The fourth edge region E4 is located on the fourth bus bar 7B side.

[0029] A pair of first mass adding films 4A are provided in a pair of edge regions of the first acoustic wave resonator 1A. Specifically, one of the pair of first mass adding films 4A is provided in the first edge region E1. The other first mass adding film 4A is provided in the second edge region E2.

[0030] The pair of first mass adding films 4A have a band-like shape. Specifically, in a plan view, one first mass adding film 4A overlaps with the plurality of first electrode fingers 8A and the plurality of second electrode fingers 9A. More specifically, the first mass adding film 4A is provided on the piezoelectric substrate 2, over the plurality of first electrode fingers 8A, and over the plurality of second electrode fingers 9A. The first mass adding film 4A is provided continuously so as to overlap with the plurality of electrode fingers and the regions between the electrode fingers of the first IDT electrode 3A in a plan view.

[0031] In this specification, a plan view refers to a view of the acoustic wave device from a direction corresponding to the top in Fig. 3. In Fig. 3, for example, of the piezoelectric substrate 2 side and the first mass adding film 4A side, the first mass adding film 4A side is the top.

[0032] 2, the width of each electrode finger of the first IDT electrode 3A in a portion overlapping with the first mass adding film 4A in a plan view is wider than the width of the electrode finger in the first central region C1. However, the width of each electrode finger of the first IDT electrode 3A may be constant. The width of the electrode finger is the dimension of the electrode finger along the direction perpendicular to the electrode finger.

[0033] In the first acoustic wave resonator 1A, a first mass adding film 4A is provided in the first edge region E1, thereby forming a low acoustic velocity region in the first edge region E1. The low acoustic velocity region in the first acoustic wave resonator 1A is a region in which the acoustic velocity is lower than that in the first central region C1. Similarly, a low acoustic velocity region is formed in the second edge region E2 by providing the first mass adding film 4A in the second edge region E2. Note that in this embodiment, the acoustic velocity in the pair of edge regions is also reduced by the fact that the width of the electrode fingers is wider in the pair of edge regions.

[0034] A pair of second mass adding films 4B are provided in a pair of edge regions of the second acoustic wave resonator 1B. One of the pair of second mass adding films 4B is provided in the third edge region E3. The other second mass adding film 4B is provided in the fourth edge region E4.

[0035] The pair of second mass adding films 4B have a band-like shape. Specifically, in a plan view, one second mass adding film 4B overlaps with a plurality of third electrode fingers 8B and a plurality of fourth electrode fingers 9B. More specifically, the second mass adding film 4B is provided on the piezoelectric substrate 2, over the plurality of third electrode fingers 8B, and over the plurality of fourth electrode fingers 9B. The second mass adding film 4B is provided continuously so as to overlap with the plurality of electrode fingers and the regions between the electrode fingers of the second IDT electrode 3B in a plan view.

[0036] In the second acoustic wave resonator 1B, a second mass adding film 4B is provided in the third edge region E3, thereby forming a low acoustic velocity region in the third edge region E3. The low acoustic velocity region in the second acoustic wave resonator 1B is a region in which the acoustic velocity is lower than that in the second central region C2. Similarly, a low acoustic velocity region is formed in the fourth edge region E4 by providing the second mass adding film 4B in the fourth edge region E4.

[0037] In the first acoustic wave resonator 1A, a first central region C1 and a pair of low acoustic velocity regions are arranged in this order from the center to the outside in the electrode finger extension direction. In the second acoustic wave resonator 1B, a second central region C2 and a pair of low acoustic velocity regions are arranged in this order from the center to the outside in the electrode finger extension direction. As a result, a piston mode is established in each of the first acoustic wave resonator 1A and the second acoustic wave resonator 1B, and a transverse mode can be suppressed.

[0038] The material of the first mass adding film 4A and the second mass adding film 4B is Ta. 2 O 5Tantalum oxide such as tantalum oxide is used. However, the materials of the first mass adding film 4A and the second mass adding film 4B are not limited to the above. Hereinafter, the first mass adding film 4A and the second mass adding film 4B may be collectively referred to simply as the mass adding film.

[0039] 3, a dielectric film 5 is provided on the piezoelectric substrate 2 so as to cover the first IDT electrode 3A, the second IDT electrode 3B, the first mass adding film 4A, and the second mass adding film 4B. This forms a laminate of the first IDT electrode 3A and the dielectric film 5, and a laminate of the second IDT electrode 3B and the dielectric film 5.

[0040] The first IDT electrode 3A and the second IDT electrode 3B are protected by the dielectric film 5. Therefore, the first IDT electrode 3A and the second IDT electrode 3B are less likely to be damaged. In this embodiment, silicon oxide is used as the material of the dielectric film 5. However, the material of the dielectric film 5 is not limited to the above. The dielectric film 5 does not necessarily have to be provided.

[0041] The present embodiment is characterized by the following configuration. 1) The thickness of the electrode fingers in the second IDT electrode 3B is thinner than the thickness of the electrode fingers in the first IDT electrode 3A. 2) The thickness of the first mass adding film 4A is the same as the thickness of the second mass adding film 4B. 3) As shown in an enlarged view in FIG. 4, the width of the electrode fingers of the second IDT electrode 3B at the portion overlapping with the second mass adding film 4B in a plan view is narrower than the width of the electrode fingers in the second central region C2. This makes it possible to more reliably suppress the transverse mode without reducing productivity. This will be described below.

[0042] First, an example of a condition for more reliably suppressing the transverse mode is shown. This condition is defined by the wavelength ratio width W and thickness ratio T Ris within a predetermined range. Here, the wavelength defined by the electrode finger pitch is defined as λ. The electrode finger pitch is the distance between the centers of adjacent electrode fingers connected to different potentials in the direction perpendicular to the electrode fingers. The value obtained by dividing the dimension of the mass-adding film along the electrode finger extension direction by the wavelength λ is defined as the wavelength ratio width W.

[0043] The product of the density and thickness of each layer of the electrode finger divided by the density of Al is defined as the equivalent Al thickness of that layer. The sum of the equivalent Al thicknesses of each layer of the electrode finger is the equivalent Al thickness of the electrode finger. For example, let n be any natural number, k be a natural number in the range of 1≦k≦n, and assume that the electrode finger has n layers. Let the density of the layer of the kth electrode finger from the piezoelectric substrate 2 side be ρ k , thickness is t k , the aluminum equivalent thickness is T k Let the density of Al be ρ Al Then, the thickness of each layer of the electrode finger in terms of Al, T k is T k ={(ρ k ·t k ) / ρ Al}. Note that ρ Al is 2.694g / cm 3 The thickness of the electrode finger converted to Al is T IDT Then, the thickness of Al is T IDT is T IDT =Σ{(ρ k T k ) / (ρ Al )}(1≦k≦n).

[0044] The product of the density and thickness of the dielectric film 5 divided by the density of Al is defined as the Al-equivalent thickness of the dielectric film 5. The density of the dielectric film 5 is ρ d , thickness is t d , the aluminum equivalent thickness is T d Then, the thickness T of the dielectric film 5 in terms of Al is d is T d ={(ρ d ·t d ) / ρ Al The thickness of the laminate of the electrode fingers and the dielectric film 5 in terms of aluminum is T T Let us assume that.

[0045] The thickness of the mass-added membrane is t m and the thickness T of the laminate of the electrode fingers and the dielectric film 5 in terms of Al T The thickness of the mass-added membrane, t m The thickness ratio of T R [%]. Thickness ratio T R is T R =(t m / T T ) × 100[%].

[0046] The transverse modes include various modes such as 1st to 11th orders. R By setting the relationship and range as shown in FIG. 5, the magnitude of the largest ripple among the ripples caused by the transverse mode in the frequency characteristics can be suppressed to 1 dB or less.

[0047] FIG. 5 shows the wavelength ratio width W and thickness ratio T of the mass-added film when the magnitude of the ripple caused by the transverse mode is 1 dB or 0.1 dB. R FIG.

[0048] In Figure 5, solid line B 1 Therefore, the wavelength ratio width W and thickness ratio T are set so that the magnitude of the ripple caused by the transverse mode in the frequency characteristics of the elastic wave resonator is 1 dB. R The combination of solid line B is shown. 1 Within the range enclosed by, the wavelength ratio width W and thickness ratio T R When the above combination is used, the magnitude of the ripple caused by the transverse mode is 1 dB or less.

[0049] In FIG. 5, range J is shown. This range J is indicated by solid line B 1 Specifically, the wavelength ratio width W and thickness ratio T at which the transverse mode is most suppressed are R The range J is the range of ±12% centered on the combination of wavelength ratio W and thickness ratio T R By keeping the value of J within this range J, the magnitude of the ripple caused by the transverse mode can be suppressed to 1 dB or less with even greater certainty.

[0050] In addition, in FIG. 5, solid line B 0.1 The wavelength ratio width W and thickness ratio T are the wavelength ratios that make the ripple caused by the transverse mode 0.1 dB. R The combination of wavelength ratio width W and thickness ratio T R The value of solid line B 0.1 By keeping the value within the range surrounded by, the magnitude of the ripple caused by the transverse mode can be suppressed to 0.1 dB or less.

[0051] Here, in the first acoustic wave resonator 1A, the thickness ratio T R When the wavelength ratio width W of the first mass adding film 4A is 0.581 λ or more and 0.739 λ or less, as shown in FIG. 5, the wavelength ratio width W and the thickness ratio T R is a value within range J. In this case, the transverse mode can be more reliably suppressed in first acoustic wave resonator 1A.

[0052] On the other hand, the thickness of the electrode fingers in the second IDT electrode 3B of the second acoustic wave resonator 1B is thinner than the thickness of the electrode fingers in the first IDT electrode 3A of the first acoustic wave resonator 1A. This makes it easier to increase the resonant frequency of the second acoustic wave resonator 1B. However, when the thickness ratio T R is different from 10.7%. An example of this is shown in Table 1.

[0053] [Table 1]

[0054] In the example of Table 1, the aluminum-equivalent thickness of the laminate of the electrode fingers and the dielectric film 5 in the second acoustic wave resonator 1B is smaller than the aluminum-equivalent thickness of the laminate of the electrode fingers and the dielectric film 5 in the first acoustic wave resonator 1A. On the other hand, the thicknesses of the mass-adding films are the same in the first acoustic wave resonator 1A and the second acoustic wave resonator 1B. Therefore, the thickness ratio T RMore specifically, in the example of Table 1, the thickness ratio T R is 13.9%. This is shown by the dashed line in FIG.

[0055] In the example of Table 1, the thickness ratio T R As shown in FIG. 5, in the first acoustic wave resonator 1A, the range of the wavelength ratio width W of the first mass adding film 4A that can suppress the transverse mode is wide. On the other hand, the thickness ratio T R is 13.9%. In this case, the transverse mode can be suppressed by setting the wavelength ratio width W of the second mass adding film 4B within the range of the wavelength ratio width W that can suppress the transverse mode shown in Fig. 5. In this case, the transverse mode can be suppressed in the first reference example shown in Fig. 6 and the second reference example shown in Fig. 7.

[0056] Specifically, in the first reference example shown in FIG. 6, the width of the electrode fingers of the second IDT electrode 23B is constant. On the other hand, the first IDT electrode 3A is configured similarly to the first embodiment. In the second reference example shown in FIG. 7, the width of the electrode fingers of the first IDT electrode 23A and the width of the electrode fingers of the second IDT electrode 23B are constant. Even in these cases, the wavelength ratio width W of the second mass adding film 4B may be set within the range of the wavelength ratio width W shown in FIG. 5, which can suppress the transverse mode. However, the range of the wavelength ratio width W of the second mass adding film 4B, which can suppress the transverse mode, is narrow.

[0057] However, by making the thickness of the second mass adding film 4B thinner than the thickness of the first mass adding film 4A, the thickness ratio T R As a result, the thickness ratio T R can be made close to a value within the range J. In this case, however, a step for making the thickness of the first mass adding film 4A and the thickness of the second mass adding film 4B different from each other is required in the manufacturing process.

[0058] Here, the inventors have found that the width of the portion of the electrode finger of the second IDT electrode 3B that overlaps with the second mass adding film 4B in a plan view is narrower than the width of the electrode finger in the second central region C2, thereby widening the range of wavelength ratio width W in which the transverse mode can be suppressed. Specifically, even if the wavelength ratio width W of the second mass adding film 4B is set outside the range in which the transverse mode can be suppressed, as shown in FIG. 5, the transverse mode can be suppressed. More specifically, even if the wavelength ratio width W of the second mass adding film 4B is narrower, the transverse mode can be suppressed.

[0059] As described above, in the elastic wave device 10 of this preferred embodiment, the first mass adding film 4A and the second mass adding film 4B have the same thickness. In addition, the width of the electrode finger of the second IDT electrode 3B at the portion overlapping with the second mass adding film 4B in a plan view is narrower than the width of the electrode finger in the second central region C2. This makes it possible to widen the range of the wavelength ratio width W in which the transverse mode of the second mass adding film 4B can be suppressed without complicating the manufacturing process. Therefore, the transverse mode can be more reliably suppressed without reducing productivity.

[0060] As in this embodiment, in the first IDT electrode 3A, the width of the portion of the electrode finger overlapping with the first mass adding film 4A in a plan view is preferably wider than the width of the electrode finger in the first central region C1.

[0061] More specifically, for example, the thickness of the electrode fingers of the first IDT electrode 3A may be increased in order to lower the resonant frequency of the first acoustic wave resonator 1A. In this case, the range of the wavelength ratio width W of the first mass adding film 4A, in which the transverse mode can be suppressed, may be narrowed. In contrast, in the present embodiment, the width of the electrode fingers of the first IDT electrode 3A at the portion overlapping with the first mass adding film 4A in a plan view is wider than the width of the electrode fingers in the first central region C1. This makes it possible to widen the range of the wavelength ratio width W in which the transverse mode can be suppressed in the first acoustic wave resonator 1A. More specifically, even when the wavelength ratio width W of the first mass adding film 4A is wider, the transverse mode can be effectively suppressed.

[0062] When the thickness of the electrode fingers in the second IDT electrode 3B is reduced to increase the resonant frequency as in the second acoustic wave resonator 1B, the thickness ratio T R However, as shown in Fig. 5, the thickness ratio T R When is large, the thickness ratio T R In contrast, in the first embodiment of the present invention, the range of wavelength ratio width W in which the second mass adding film 4B can suppress the transverse mode in the second acoustic wave resonator 1B can be made wider. Therefore, the configuration of the present invention is suitable for suppressing the transverse mode without reducing productivity.

[0063] The configuration of the first embodiment will be described in further detail below. As shown in Fig. 2, a pair of gap regions are disposed between the first intersection region A1 and the pair of bus bars of the first acoustic wave resonator 1A. Specifically, the pair of gap regions are a first gap region G1 and a second gap region G2. The first gap region G1 is located on the first bus bar 6A side. The second gap region G2 is located on the second bus bar 7A side.

[0064] In the first gap region G1, only the first electrode fingers 8A out of the first electrode fingers 8A and the second electrode fingers 9A are provided. This defines a high acoustic velocity region in the first gap region G1. The high acoustic velocity region in the first acoustic wave resonator 1A refers to a region in which the acoustic velocity is higher than that in the first central region C1. A high acoustic velocity region is also defined in the second gap region G2 in a similar manner.

[0065] The second acoustic wave resonator 1B has a pair of gap regions, a third gap region G3 and a fourth gap region G4. The third gap region G3 is located on the third bus bar 6B side. The fourth gap region G4 is located on the fourth bus bar 7B side. In the second acoustic wave resonator 1B, high acoustic velocity regions are formed in the third gap region G3 and the fourth gap region G4. The high acoustic velocity regions in the second acoustic wave resonator 1B refer to regions in which the acoustic velocity is higher than that in the second central region C2.

[0066] In the first acoustic wave resonator 1A, a first central region C1, a pair of low acoustic velocity regions, and a pair of high acoustic velocity regions are arranged in this order from inside to outside in the electrode finger extension direction. This makes it possible to more reliably suppress transverse modes. In the second acoustic wave resonator 1B, a second central region C2, a pair of low acoustic velocity regions, and a pair of high acoustic velocity regions are arranged in this order from inside to outside in the electrode finger extension direction. This makes it possible to more reliably suppress transverse modes.

[0067] In the first acoustic wave resonator 1A of the first embodiment, the first mass adding film 4A is provided in each edge region. The first mass adding film 4A may be provided in at least one of the first edge region E1 and the second edge region E2. However, it is preferable that the first mass adding film 4A is provided in both the first edge region E1 and the second edge region E2. This makes it possible to more reliably and effectively suppress the transverse mode.

[0068] Similarly, in the second acoustic wave resonator 1B, the second mass adding film 4B may be provided in at least one of the third edge region E3 and the fourth edge region E4. However, it is preferable that the second mass adding film 4B is provided in both the third edge region E3 and the fourth edge region E4. This makes it possible to more reliably and effectively suppress the transverse mode.

[0069] As shown in FIG. 4, the tip of the fourth electrode finger 9B of the second IDT electrode 3B does not overlap the second mass adding film 4B in a plan view. In a plan view, the distance between the tip of the fourth electrode finger 9B and the edge of the tip of the fourth electrode finger 9B in the second mass adding film 4B located in the third edge region E3 in the electrode finger extension direction is preferably 0.1 λ or less. Similarly, in a plan view, the distance between the tip of the third electrode finger 8B shown in FIG. 1 and the edge of the tip of the third electrode finger 8B in the second mass adding film 4B located in the fourth edge region E4 in the electrode finger extension direction is preferably 0.1 λ or less. Note that the tip of the electrode finger of the second IDT electrode 3B may overlap the second mass adding film 4B in a plan view.

[0070] On the other hand, the tips of the electrode fingers of the first IDT electrode 3A overlap with the first mass adding film 4A in a plan view. However, the tips of the electrode fingers of the first IDT electrode 3A do not have to overlap with the first mass adding film 4A in a plan view. In this case, it is preferable that the distance between the tip of the second electrode finger 9A and the edge of the first mass adding film 4A located in the first edge region E1 on the tip side of the second electrode finger 9A in the electrode finger extension direction in a plan view is 0.1 λ or less. It is preferable that the distance between the tip of the first electrode finger 8A and the edge of the first mass adding film 4A located in the second edge region E2 on the tip side of the first electrode finger 8A in the electrode finger extension direction in a plan view is 0.1 λ or less.

[0071] 3, in the first acoustic wave resonator 1A, the first mass adding film 4A is provided between the first electrode fingers 8A and the second electrode fingers 9A and the dielectric film 5. However, for example, the first mass adding film 4A, the electrode fingers, and the dielectric film 5 may be laminated in this order from the piezoelectric substrate 2 side. Alternatively, the electrode fingers, the dielectric film 5, and the first mass adding film 4A may be laminated in this order from the piezoelectric substrate 2 side.

[0072] In the second acoustic wave resonator 1B, the second mass adding film 4B is provided between the third electrode fingers 8B and the fourth electrode fingers 9B and the dielectric film 5. However, for example, the second mass adding film 4B, the electrode fingers, and the dielectric film 5 may be laminated in this order from the piezoelectric substrate 2 side. Alternatively, the electrode fingers, the dielectric film 5, and the second mass adding film 4B may be laminated in this order from the piezoelectric substrate 2 side.

[0073] The piezoelectric substrate 2 of the acoustic wave device 10 is a laminated substrate. Specifically, the piezoelectric substrate 2 includes a support substrate 13, a high acoustic velocity film 14, a low acoustic velocity film 15, and a piezoelectric layer 16. The high acoustic velocity film 14 is provided on the support substrate 13. The low acoustic velocity film 15 is provided on the high acoustic velocity film 14. The piezoelectric layer 16 is provided on the low acoustic velocity film 15.

[0074] In the first embodiment, the material of the piezoelectric layer 16 is LiTaO 3 Lithium tantalate such as lithium tantalate is used. Note that the material of the piezoelectric layer 16 is not limited to the above, and for example, lithium niobate, zinc oxide, aluminum nitride, quartz crystal, PZT (lead zirconate titanate), etc. can also be used.

[0075] The low acoustic velocity film 15 is a film with a relatively low acoustic velocity. Specifically, the acoustic velocity of the bulk wave propagating through the low acoustic velocity film 15 is lower than that of the bulk wave propagating through the piezoelectric layer 16. The low acoustic velocity film 15 may be made of 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 thereto, or a material containing the above-mentioned material as a main component. In this specification, the main component refers to a component that accounts for more than 50 wt%. The above-mentioned main component material may be in any one of a single crystal, polycrystal, and amorphous state, or a mixture of these.

[0076] The high acoustic velocity film 14 is a film with a relatively high acoustic velocity. Specifically, the bulk wave propagating through the high acoustic velocity film 14 has a higher acoustic velocity than the elastic wave propagating through the piezoelectric layer 16. Examples of the material of the high acoustic velocity film 14 include piezoelectric materials such as aluminum nitride, lithium tantalate, lithium niobate, and quartz; ceramics such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, spinel, and sialon; dielectric materials such as aluminum oxide, silicon oxynitride, DLC (diamond-like carbon), and diamond; semiconductors such as silicon; and materials containing the above materials as main components. The spinel includes aluminum compounds containing one or more elements selected from Mg, Fe, Zn, Mn, and the like, and oxygen. Examples of the spinel include MgAl 2 O 4 , FeAl 2 O 4 , ZnAl 2 O 4 , MnAl 2 O 4 Examples include:

[0077] Examples of materials that can be used for the support substrate 13 include piezoelectric materials such as aluminum nitride, lithium tantalate, lithium niobate, and quartz; ceramics such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, and forsterite; dielectric materials such as diamond and glass; semiconductors such as silicon and gallium nitride; or resins, or materials containing any of the above materials as a main component.

[0078] A high acoustic velocity film 14, a low acoustic velocity film 15, and a piezoelectric layer 16 are laminated in this order on the piezoelectric substrate 2. This makes it possible to effectively confine the energy of the acoustic waves on the piezoelectric layer 16 side.

[0079] The laminated structure of the piezoelectric substrate is not limited to the above. For example, the piezoelectric substrate may be a laminated substrate of a support substrate, a high acoustic velocity film, and a piezoelectric layer. Alternatively, the piezoelectric substrate may have a high acoustic velocity support substrate made of the same material as the high acoustic velocity film. The acoustic velocity of the bulk wave propagating through the high acoustic velocity support substrate is higher than the acoustic velocity of the elastic wave propagating through the piezoelectric layer. In this case, the piezoelectric substrate may be a laminated substrate of a high acoustic velocity support substrate, a low acoustic velocity film, and a piezoelectric layer, or may be a laminated substrate of a high acoustic velocity support substrate and a piezoelectric layer. In these cases, the energy of the elastic wave can be effectively trapped on the piezoelectric layer side.

[0080] Table 2 shows examples of metal materials and dielectric materials, and the density of each material. The metals listed in Table 2 may be used as the material of the first IDT electrode 3A and the second IDT electrode 3B shown in FIG. 3. The dielectric film 5 may be used as the material of the dielectric film 5. Furthermore, the dielectrics listed in Table 2 may be used as the material of the first mass addition film 4A and the second mass addition film 4B. The metal materials used for the first IDT electrode 3A and the second IDT electrode 3B, and the dielectric materials used for the dielectric film 5, the first mass addition film 4A, or the second mass addition film 4B may contain a small amount of a different material. For example, the Al layer may contain a small amount of Cu.

[0081] [Table 2]

[0082] As described above, in the first embodiment, the first acoustic wave resonator 1A and the second acoustic wave resonator 1B are surface acoustic wave resonators. The resonant frequencies of the surface acoustic wave resonators can be compared using the electrode finger pitch and the duty ratio of the IDT electrodes. When the electrode finger thicknesses of the surface acoustic wave resonators are different from each other, the resonant frequency of the surface acoustic wave resonator having a larger reciprocal of the product of the electrode finger pitch, the duty ratio, and the electrode finger thickness is higher than the resonant frequency of the other surface acoustic wave resonator.

[0083] It is preferable that the reciprocal of the product of the electrode finger pitch, duty ratio, and electrode finger thickness of the second IDT electrode 3B in the second acoustic wave resonator 1B is larger than the reciprocal of the electrode finger pitch, duty ratio, and electrode finger thickness of the first IDT electrode 3A in the first acoustic wave resonator 1A. In this case, the resonant frequency of the second acoustic wave resonator 1B is higher than the resonant frequency of the first acoustic wave resonator 1A. In the first embodiment, the thickness of the multiple electrode fingers in the second IDT electrode 3B is thinner than the thickness of the multiple electrode fingers in the first IDT electrode 3A. This makes it possible to suitably make the resonant frequency of the second acoustic wave resonator 1B higher than the resonant frequency of the first acoustic wave resonator 1A.

[0084] This allows suitable use of the first filter device 10A including the first acoustic wave resonator 1A and the second filter device 10B including the second acoustic wave resonator 1B. The first filter device 10A can be used, for example, as a band-pass filter for a middle band. The second filter device 10B can be used, for example, as a band-pass filter for a high band.

[0085] Incidentally, the width of the portion of the electrode finger of the first IDT electrode 3A that overlaps with the first mass adding film 4A in a plan view does not necessarily need to be wider than the width of the electrode finger in the first central region C1. For example, in the modification of the first embodiment shown in FIG. 8, the width of the electrode finger of the first IDT electrode 23A is constant. In this case, in the first acoustic wave resonator, the thickness ratio T R and the wavelength ratio width W of the first mass adding film 4A is preferably within the range J shown in Fig. 5, for example. Meanwhile, the width of the electrode fingers of the second IDT electrode 3B at the portion overlapping with the second mass adding film 4B in a plan view is narrower than the width of the electrode fingers at the second central region C2. This makes it possible to more reliably suppress the transverse mode without reducing productivity, as in the first embodiment.

[0086] Fig. 9 is a schematic plan view of a first acoustic wave resonator and a second acoustic wave resonator according to the second embodiment, and Fig. 10 is a schematic plan view showing an enlarged view of an area around one electrode finger of a first IDT electrode and an area around one electrode finger of a second IDT electrode according to the second embodiment.

[0087] This embodiment differs from the first embodiment in that a plurality of mass-adding films are provided in each edge region. Except for the above, the elastic wave device of this embodiment has a similar configuration to elastic wave device 10 of the first embodiment.

[0088] A plurality of first mass adding films 34A are provided in the first edge region E1 of the first acoustic wave resonator 1A. A plurality of first mass adding films 34A are also provided in the second edge region E2. Each first mass adding film 34A overlaps one electrode finger in a planar view. In this embodiment, the first mass adding film 34A is provided only in a portion overlapping the electrode finger in a planar view. However, the first mass adding film 34A may extend from the portion overlapping the electrode finger in a planar view to a portion overlapping the region between the electrode fingers in a planar view.

[0089] A plurality of second mass adding films 34B are provided in the third edge region E3 of the second acoustic wave resonator 1B. A plurality of second mass adding films 34B are also provided in the fourth edge region E4. Each second mass adding film 34B overlaps one electrode finger in a plan view. In this embodiment, the second mass adding film 34B is provided only in a portion overlapping the electrode finger in a plan view. However, the second mass adding film 34B may extend from the portion overlapping the electrode finger in a plan view to a portion overlapping the region between the electrode fingers in a plan view.

[0090] In the present embodiment, the width of the electrode finger of the second IDT electrode 3B in the portion overlapping with the second mass adding film 34B in a plan view is narrower than the width of the electrode finger in the second central region C2, thereby making it possible to more reliably suppress the transverse mode without reducing productivity, as in the first embodiment.

[0091] The width of the electrode finger of the first IDT electrode 3A at the portion overlapping the first mass adding film 34A in a plan view does not necessarily have to be wide. For example, in the modification of the second embodiment shown in FIG. 11, the width of the electrode finger of the first IDT electrode 23A is constant. In this case, in the first acoustic wave resonator, the thickness ratio T R and the wavelength ratio width W of the first mass adding film 34A is preferably within the range J shown in Fig. 5. Meanwhile, the width of the electrode fingers of the second IDT electrode 3B at the portion overlapping with the second mass adding film 34B in a plan view is narrower than the width of the electrode fingers at the second central region C2. This makes it possible to more reliably suppress the transverse mode without reducing productivity, as in the second embodiment.

[0092] The first mass adding film 34A is not in contact with the electrode fingers connected to different potentials. Similarly, the second mass adding film 34B is not in contact with the electrode fingers connected to different potentials. In this case, the first mass adding film 34A and the second mass adding film 34B may be made of a metal. However, the first mass adding film 34A and the second mass adding film 34B may be made of a dielectric material.

[0093] FIG. 12 is a schematic diagram of an elastic wave device according to a third preferred embodiment of the present invention.

[0094] The elastic wave device 40 of this preferred embodiment is a multiplexer. The elastic wave device 40 includes a common connection terminal 45, a first filter device 10A, and a second filter device 10B. The first filter device 10A and the second filter device 10B are commonly connected to the common connection terminal 45. The common connection terminal 45 may be configured as, for example, an electrode pad or a wiring.

[0095] The first filter device 10A and the second filter device 10B are configured similarly to the first embodiment. That is, the first filter device 10A includes a first acoustic wave resonator 1A shown in Fig. 2. The second filter device 10B includes a second acoustic wave resonator 1B shown in Fig. 2. Therefore, similar to the first embodiment, it is possible to suppress the transverse mode without reducing productivity.

[0096] The elastic wave device 40 may include at least one filter device other than the first filter device 10A and the second filter device 10B. The filter device may be connected in common to the first filter device 10A and the second filter device 10B to a common connection terminal 45. The number of filter devices in the elastic wave device 40 is not particularly limited.

[0097] In the present invention, first acoustic wave resonator 1A and second acoustic wave resonator 1B may be included in one band-pass filter.

[0098] Examples of configurations of the elastic wave device according to the present invention will be described below.

[0099] <1> a first acoustic wave resonator including a piezoelectric substrate and a first IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate; and a second acoustic wave resonator sharing the piezoelectric substrate with the first acoustic wave resonator and including a second IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate, wherein in the first IDT electrode, a region where adjacent electrode fingers overlap each other when viewed from a direction perpendicular to a direction in which the electrode fingers extend is a first crossing region, and the first crossing region has a first central region, and a first edge region and a second edge region sandwiching the first central region in the direction in which the electrode fingers extend, and a second crossing region where adjacent electrode fingers overlap each other when viewed from a direction perpendicular to the direction in which the electrode fingers extend is a second crossing region, and the second crossing region has a second central region and a second edge region sandwiching the first central region in the direction in which the electrode fingers extend. a first mass adding film provided in at least one of the first edge region and the second edge region and overlapping with the plurality of electrode fingers of the first IDT electrode in a planar view; and a second mass adding film provided in at least one of the third edge region and the fourth edge region and overlapping with the plurality of electrode fingers of the second IDT electrode in a planar view, wherein a thickness of the plurality of electrode fingers of the second IDT electrode is thinner than a thickness of the plurality of electrode fingers of the first IDT electrode, a thickness of the first mass adding film is the same as a thickness of the second mass adding film, and a width of a portion of the electrode fingers of the second IDT electrode overlapping with the second mass adding film in a planar view is narrower than a width of the electrode fingers in the second central region.

[0100] <2> a width of the electrode finger of the first IDT electrode at a portion overlapping with the first mass addition film in a plan view is wider than a width of the electrode finger at the first central region; <1> The acoustic wave device according to claim 1 .

[0101] <3> a dimension of the first mass adding film along a direction in which the electrode fingers of the first IDT electrode extend is defined as a width of the first mass adding film, and a dimension of the second mass adding film along a direction in which the electrode fingers of the second IDT electrode extend is defined as a width of the second mass adding film, the width of the first mass adding film being wider than the width of the second mass adding film. <1> or <2> The acoustic wave device according to claim 1 .

[0102] <4> the first mass-adding film is provided continuously so as to overlap with the plurality of electrode fingers of the first IDT electrode and regions between the electrode fingers in a plan view, and the second mass-adding film is provided continuously so as to overlap with the plurality of electrode fingers of the second IDT electrode and regions between the electrode fingers in a plan view. <1> ~ <3> 13. The acoustic wave device according to claim 12,

[0103] <5> a plurality of the first mass adding films are provided in at least one of the first edge region and the second edge region, one of the first mass adding films being provided so as to overlap one of the electrode fingers of the first IDT electrode in a planar view; a plurality of the second mass adding films are provided in at least one of the third edge region and the fourth edge region, one of the second mass adding films being provided so as to overlap one of the electrode fingers of the second IDT electrode in a planar view; <1> ~ <3> 13. The acoustic wave device according to claim 12,

[0104] <6> A metal is used as a material for the first mass addition film and the second mass addition film. <5> The acoustic wave device according to claim 1 .

[0105] <7> the first mass-adding film is provided on both the first edge region and the second edge region, and the second mass-adding film is provided on both the third edge region and the fourth edge region; <1> ~ <6> 13. The acoustic wave device according to claim 12,

[0106] <8> a resonant frequency of the second acoustic wave resonator is higher than a resonant frequency of the first acoustic wave resonator; <1> ~ <7> 13. The acoustic wave device according to claim 12,

[0107] <9> a first filter device including the first acoustic wave resonator and a second filter device including the second acoustic wave resonator, the first filter device and the second filter device being connected to different signal potentials; <1> ~ <8> 13. The acoustic wave device according to claim 12,

[0108] <10> a first filter device including the first acoustic wave resonator, a second filter device including the second acoustic wave resonator, and a common connection terminal to which the first filter device and the second filter device are commonly connected. <1> ~ <8> 13. The acoustic wave device according to claim 12, [Explanation of symbols]

[0109] 1A, 1B...First and second elastic wave resonators 2...Piezoelectric substrate 3A, 3B: First and second IDT electrodes 4A, 4B: First and second mass-added membranes 5...Dielectric film 6A, 7A...1st and 2nd bus bars 6B, 7B: 3rd and 4th bus bars 8A, 9A: First and second electrode fingers 8B, 9B: 3rd and 4th electrode fingers 10...Elastic wave device 10A, 10B...First and second filter devices 13…Support substrate 14…High-sonic membrane 15…Low sound velocity membrane 16...Piezoelectric layer 18A~18D…Reflector 23A, 23B...First and second IDT electrodes 34A, 34B... First and second mass-adding membranes 40...Elastic wave device 45...Common connection terminal A1, A2: First and second intersection areas C1, C2: 1st and 2nd central regions E1 to E4: 1st to 4th edge regions G1~G4: 1st to 4th gap regions

Claims

1. a first acoustic wave resonator including a piezoelectric substrate and a first IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate; a second acoustic wave resonator sharing the piezoelectric substrate with the first acoustic wave resonator and having a second IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate; Equipped with in the first IDT electrode, a region where adjacent electrode fingers overlap each other when viewed from a direction perpendicular to a direction in which the electrode fingers extend is a first intersection region, the first intersection region having a first central region, and a first edge region and a second edge region sandwiching the first central region in the direction in which the electrode fingers extend, in the second IDT electrode, a region where adjacent electrode fingers overlap each other when viewed from a direction perpendicular to a direction in which the electrode fingers extend is a second intersection region, the second intersection region having a second central region, and a third edge region and a fourth edge region sandwiching the second central region in the direction in which the electrode fingers extend, a first mass-adding film provided in at least one of the first edge region and the second edge region and overlapping the plurality of electrode fingers of the first IDT electrode in a plan view; a second mass-adding film provided in at least one of the third edge region and the fourth edge region and overlapping the plurality of electrode fingers of the second IDT electrode in a plan view; Further equipped with a thickness of the plurality of electrode fingers in the second IDT electrode is smaller than a thickness of the plurality of electrode fingers in the first IDT electrode; the thickness of the first mass-adding film is the same as the thickness of the second mass-adding film; the width of a portion of the electrode finger of the second IDT electrode that overlaps with the second mass addition film in a plan view is narrower than the width of the electrode finger in the second central region.

2. 2 . The acoustic wave device according to claim 1 , wherein a width of the electrode finger of the first IDT electrode at a portion overlapping with the first mass addition film in a planar view is wider than a width of the electrode finger at the first central region.

3. 2. The elastic wave device according to claim 1, wherein when a dimension of the first mass-adding film along a direction in which the electrode fingers in the first IDT electrode extend is defined as a width of the first mass-adding film, and a dimension of the second mass-adding film along a direction in which the electrode fingers in the second IDT electrode extend is defined as a width of the second mass-adding film, the width of the first mass-adding film is wider than the width of the second mass-adding film.

4. the first mass-adding film is provided continuously so as to overlap the electrode fingers of the first IDT electrode and regions between the electrode fingers in a plan view, The acoustic wave device according to claim 1 , wherein the second mass-adding film is provided continuously so as to overlap with the plurality of electrode fingers of the second IDT electrode and regions between the electrode fingers in a plan view.

5. a plurality of the first mass adding films are provided in at least one of the first edge region and the second edge region, and one of the first mass adding films is provided so as to overlap one of the electrode fingers of the first IDT electrode in a plan view; 2. The elastic wave device according to claim 1, wherein a plurality of the second mass-adding films are provided in at least one of the third edge region and the fourth edge region, and one of the second mass-adding films is provided so as to overlap one of the electrode fingers of the second IDT electrode in a planar view.

6. The acoustic wave device according to claim 5 , wherein the first mass addition film and the second mass addition film are made of a metal.

7. 2. The elastic wave device according to claim 1, wherein the first mass-adding film is provided in both the first edge region and the second edge region, and the second mass-adding film is provided in both the third edge region and the fourth edge region.

8. The acoustic wave device according to claim 1 , wherein a resonant frequency of the second acoustic wave resonator is higher than a resonant frequency of the first acoustic wave resonator.

9. a first filter device including the first acoustic wave resonator; a second filter device including the second acoustic wave resonator; and Equipped with The acoustic wave device according to claim 1 , wherein the first filter device and the second filter device are connected to different signal potentials.

10. a first filter device including the first acoustic wave resonator; a second filter device including the second acoustic wave resonator; and a common connection terminal to which the first filter device and the second filter device are commonly connected; The acoustic wave device according to claim 1 .

Images