Elastic wave device

Abstract

In an elastic wave device, a first intersection region of a first IDT electrode of a first elastic wave resonator has a first central region and first and second edge regions, a second intersection region of a second IDT electrode of a second elastic wave resonator has a second central region and third and fourth edge regions, a first mass-added film is provided in at least one of the first and second edge regions, and a second mass-added film is provided in at least one of the first and second edge regions. The first mass-added film is provided in at least one of the first and fourth edge regions and overlaps the plurality of electrode fingers of the first IDT electrode in a plan view, the second mass-added film is provided in at least one of the third and fourth edge regions and overlaps the plurality of electrode fingers of the second IDT electrode in a plan view, the plurality of electrode fingers in the second IDT electrode are thinner than the plurality of electrode fingers in the first IDT electrode, and the first and second mass-added films have the same thickness. The width of the portion of the electrode finger of the second IDT electrode that overlaps the second mass-added film in plan view is narrower than the width of the electrode finger in the second central region.

Description

Technical Field

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

[0002] In the past, elastic wave devices have been widely used as filters for portable phones and the like. An example of an elastic wave device is disclosed in the following patent document 1. In the elastic 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-added film is provided in each low-acoustic-velocity region. The above structure can suppress the stray caused by the transverse mode.

[0003] In the elastic wave device described in the following patent document 2, an IDT electrode is provided on the piezoelectric layer. Moreover, 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 finger in the edge region is wider than the width of the electrode finger in the central region. With the above structure, it is possible to suppress the stray caused by the transverse mode.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-092095

[0007] Patent Document 2: International Publication No. 2021 / 065684

[0008] However, when an elastic wave device has a plurality of elastic wave resonators, the resonant frequencies of these elastic wave resonators are often different from each other. In this case, it is necessary to adjust the structure for suppressing the transverse mode for each elastic wave resonator. Therefore, there is a concern that the productivity of the elastic wave device may be reduced. Summary of the invention

[0009] Problem that the invention aims to solve

[0010] An object of the present invention is to provide an elastic wave device that can more reliably suppress a transverse mode without reducing productivity.

[0011] Technical solutions to solve problems

[0012] The elastic wave device according to the present invention comprises: a first elastic wave resonator having a piezoelectric substrate and a first IDT electrode including a plurality of electrode fingers disposed 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 disposed on the piezoelectric substrate, wherein in the first IDT electrode, when viewed from a direction perpendicular to the direction in which the plurality of electrode fingers extend, a region where the adjacent electrode fingers overlap each other is a first intersection region, and the first intersection 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 plurality of electrode fingers extend, and in the second IDT electrode, when viewed from a direction perpendicular to the direction in which the plurality of electrode fingers extend, a region where the adjacent electrode fingers overlap each other is a second intersection region, and the second intersection region has a second intersection region. 2 central region, and a third edge region and a fourth edge region sandwiching the second central region in a direction in which the plurality of electrode fingers extend, the elastic wave device further comprising: a first mass addition 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 plan view; and a second mass addition 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 plan view, the thickness of the plurality of electrode fingers in the second IDT electrode being thinner than the thickness of the plurality of electrode fingers in the first IDT electrode, the thickness of the first mass addition film being the same as the thickness of the second mass addition film, and the width of a portion of the electrode finger of the second IDT electrode overlapping with the second mass addition film in a plan view being narrower than the width of the electrode finger in the second central region.

[0013] Effects of the Invention

[0014] According to the elastic wave device of the present invention, it is possible to provide an elastic wave device that can more reliably suppress a transverse mode without reducing productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the elastic wave device according to the first embodiment of the present invention.

[0016] Figure 2 It is a schematic plan view of a first elastic wave resonator and a second elastic wave resonator according to the first embodiment of the present invention.

[0017] Figure 3 1 is a schematic front cross-sectional view showing the vicinity of a pair of electrode fingers of a first elastic wave resonator and the vicinity of a pair of electrode fingers of a second elastic wave resonator in the first embodiment of the present invention.

[0018] Figure 4 This is a schematic plan view showing, in enlarged form, the vicinity of one electrode finger of the first IDT electrode and the vicinity of one electrode finger of the second IDT electrode in the first embodiment of the present invention.

[0019] Figure 5 The width W and thickness ratio T of the mass-added film relative to the wavelength at which the magnitude of the ripple caused by the transverse mode becomes 1 dB or 0.1 dB are shown. R Graph of the relationship.

[0020] Figure 6 It is a schematic plan view showing, in enlarged form, the vicinity of one electrode finger of the first IDT electrode and the vicinity of one electrode finger of the second IDT electrode in the first reference example.

[0021] Figure 7 It is a schematic plan view showing, in enlarged form, the vicinity of one electrode finger of the first IDT electrode and the vicinity of one electrode finger of the second IDT electrode in the second reference example.

[0022] Figure 8 This is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of the first IDT electrode and the vicinity of one electrode finger of the second IDT electrode in a modification of the first embodiment of the present invention.

[0023] Fig. 9 It is a schematic plan view of a first elastic wave resonator and a second elastic wave resonator according to a second embodiment of the present invention.

[0024] Fig.10 This is a schematic plan view showing, in enlarged form, the vicinity of one electrode finger of the first IDT electrode and the vicinity of one electrode finger of the second IDT electrode in the second embodiment of the present invention.

[0025] Fig.11 This is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of the first IDT electrode and the vicinity of one electrode finger of the second IDT electrode in a modified example of the second embodiment of the present invention.

[0026] Fig.12 It is a schematic diagram of an elastic wave device according to a third embodiment of the present invention.

[0027] Description of Reference Numerals

[0028] 1A, 1B... first and second elastic wave resonators;

[0029] 2… piezoelectric substrate;

[0030] 3A, 3B ... the first and second IDT electrodes;

[0031] 4A, 4B…1st and 2nd quality additional films;

[0032] 5… Dielectric film;

[0033] 6A, 7A…1st and 2nd bus bars;

[0034] 6B, 7B…3rd and 4th bus bars;

[0035] 8A, 9A…1st and 2nd electrode fingers;

[0036] 8B, 9B…the third and fourth electrode fingers;

[0037] 10…Elastic wave device;

[0038] 10A, 10B ... first and second filter devices;

[0039] 13...support base plate;

[0040] 14…High sound velocity membrane;

[0041] 15…Low sound velocity membrane;

[0042] 16… piezoelectric layer;

[0043] 18A~18D…reflector;

[0044] 23A, 23B ... first and second IDT electrodes;

[0045] 34A, 34B ... 1st and 2nd quality additional films;

[0046] 40…Elastic wave device;

[0047] 45…Common connection terminal;

[0048] A1, A2…1st and 2nd intersection areas;

[0049] C1, C2…1st and 2nd central areas;

[0050] E1~E4…1st to 4th marginal areas;

[0051] G1 to G4...1st to 4th gap regions. DETAILED DESCRIPTION

[0052] Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

[0053] In addition, it should be noted that each embodiment described in this specification is an example, and some structures can be replaced or combined between different embodiments.

[0054] Figure 1It is a schematic diagram of the elastic wave device according to the first embodiment of the present invention. Figure 2 FIG. 1 is a schematic top view of the first elastic wave resonator and the second elastic wave resonator in the first embodiment. Figure 2 In the figure, the dielectric film described later is omitted.

[0055] Figure 1 The elastic wave device 10 shown is a composite filter device. The elastic wave device 10 has a first filter device 10A and a second filter device 10B. Specifically, the first filter device 10A and the second filter device 10B are bandpass filters. The first filter device 10A and the second filter device 10B can 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.

[0056] However, 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 first filter device 10A and the input potential side or the output potential side of second filter device 10B may be commonly connected to terminals of the same signal potential.

[0057] The passband of the first filter device 10A and the passband of the second filter device 10B are different from each other. More specifically, the passband of the second filter device 10B is located at a position closer to the high-frequency side than the passband of the first filter device 10A. The first filter device 10A can also be used as a bandpass filter for a medium frequency band, for example. The second filter device 10B can also be used as a bandpass filter for a high frequency band, for example.

[0058] The first filter device 10A has Figure 2 The first elastic wave resonator 1A shown in FIG. 1A and the second filter device 10B include Figure 2 The resonant frequency of the second elastic wave resonator 1B is higher than the resonant frequency of the first elastic wave resonator 1A. Figure 2 , first elastic wave resonator 1A and second elastic wave resonator 1B are schematically shown side by side. However, the arrangement of first elastic wave resonator 1A and second elastic wave resonator 1B is not particularly limited.

[0059] The first elastic wave resonator 1A and the second elastic wave resonator 1B share a piezoelectric substrate 2. The piezoelectric substrate 2 is a substrate having piezoelectricity. In the present embodiment, the piezoelectric substrate 2 is a laminated substrate including a piezoelectric layer 16. Alternatively, the piezoelectric substrate 2 may be a substrate containing only a piezoelectric material.

[0060] The first elastic wave resonator 1A includes a first IDT electrode 3A. The first IDT electrode 3A is provided on the piezoelectric substrate 2. Hereinafter, the phrase "provided on the piezoelectric substrate 2" means "provided on the piezoelectric layer 16" unless otherwise specified.

[0061] The first IDT electrode 3A has a pair of bus bars and a plurality of electrode fingers. The pair of bus bars is specifically the first bus bar 6A and the second bus bar 7A. The first bus bar 6A and the second bus bar 7A are opposite to each other. The plurality of electrode fingers are specifically the plurality of first electrode fingers 8A and the plurality of second electrode fingers 9A. One end of the plurality of first electrode fingers 8A is respectively connected to the first bus bar 6A. One end of the plurality of second electrode fingers 9A is respectively connected to the second bus bar 7A. The first electrode finger 8A and the second electrode finger 9A are connected to different potentials from each other. The plurality of first electrode fingers 8A and the plurality of second electrode fingers 9A are interlaced with each other.

[0062] The second elastic wave resonator 1B has a second IDT electrode 3B. The second IDT electrode 3B is provided on the 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 are opposed to each other. The plurality of electrode fingers are specifically a plurality of third electrode fingers 8B and a plurality of fourth electrode fingers 9B. One end of the plurality of third electrode fingers 8B is respectively connected to the third bus bar 6B. One end of the plurality of fourth electrode fingers 9B is respectively connected to the fourth bus bar 7B. The plurality of third electrode fingers 8B and the plurality of fourth electrode fingers 9B are interlaced with each other.

[0063] Figure 3 1 is a schematic front cross-sectional view showing the vicinity of a pair of electrode fingers of a first elastic wave resonator and the vicinity of a pair of electrode fingers of a second elastic wave resonator in the first embodiment. Figure 3 It is a schematic front cross-sectional view of a first edge region and a third edge region described later.

[0064] The thickness of the electrode fingers in second IDT electrode 3B is thinner than the thickness of the electrode fingers in first IDT electrode 3A. This makes it easier to increase the resonant frequency of second elastic wave resonator 1B and to lower the resonant frequency of first elastic wave resonator 1A.

[0065] Back to Figure 2, the direction in which the plurality of first electrode fingers 8A and the plurality of second electrode fingers 9A extend is set as the electrode finger extending direction of the first IDT electrode 3A, and the direction orthogonal to the electrode finger extending direction is set as the electrode finger orthogonal direction of the first IDT electrode 3A. The direction in which the plurality of third electrode fingers 8B and the plurality of fourth electrode fingers 9B extend is set as the electrode finger extending direction of the second IDT electrode 3B, and the direction orthogonal to the electrode finger extending direction is set as the electrode finger orthogonal direction of the second IDT electrode 3B. However, in the present embodiment, in the first elastic wave resonator 1A and the second elastic wave resonator 1B, the electrode finger extending directions are parallel to each other, and the electrode finger orthogonal directions are parallel to each other.

[0066] By applying an AC voltage to the first IDT electrode 3A, elastic waves are excited. A pair of reflectors 18A and 18B are provided on both sides of the elastic wave propagation direction of the first IDT electrode 3A on the piezoelectric substrate 2. The first elastic wave resonator 1A is a surface acoustic wave resonator. In addition, the elastic wave propagation direction of the first IDT electrode 3A is parallel to the electrode finger orthogonal direction.

[0067] By applying an AC voltage to the second IDT electrode 3B, elastic waves are excited. A pair of reflectors 18C and 18D are provided on both sides of the elastic wave propagation direction of the second IDT electrode 3B on the piezoelectric substrate 2. The second elastic wave resonator 1B is a surface acoustic wave resonator. In addition, the elastic wave propagation direction of the second IDT electrode 3B is parallel to the electrode finger orthogonal direction.

[0068] In the present embodiment, the first IDT electrode 3A, the second IDT electrode 3B and each reflector include a stacked metal film. Specifically, among them, a Ti layer, an Al layer and a Ti layer are stacked 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 the above materials. Alternatively, the first IDT electrode 3A, the second IDT electrode 3B and each reflector may also include a single-layer metal film.

[0069] In the first IDT electrode 3A, when viewed from the orthogonal direction of the electrode fingers, the area where the adjacent first electrode fingers 8A and second electrode fingers 9A overlap each other is the first intersection area A1. The first intersection area A1 has a first central area C1 and a pair of edge areas. The pair of edge areas are specifically the first edge area E1 and the second edge area E2. The first edge area E1 and the second edge area E2 are opposite to each other with the first central area C1 sandwiched in the extending direction of the electrode fingers. The first edge area E1 is located on the first bus bar 6A side. The second edge area E2 is located on the second bus bar 7A side.

[0070] In the second IDT electrode 3B, when viewed from the orthogonal direction of the electrode fingers, the area where the adjacent third electrode fingers 8B and fourth electrode fingers 9B overlap each other is the second intersection area A2. The second intersection area A2 has a second central area C2 and a pair of edge areas. The pair of edge areas are specifically the third edge area E3 and the fourth edge area E4. The third edge area E3 and the fourth edge area E4 are opposite to each other with the second central area C2 sandwiched in the extension direction of the electrode fingers. The third edge area E3 is located on the third bus bar 6B side. The fourth edge area E4 is located on the fourth bus bar 7B side.

[0071] A pair of first mass addition films 4A are provided in a pair of edge regions of the first elastic wave resonator 1A. Specifically, one first mass addition film 4A of the pair of first mass addition films 4A is provided in the first edge region E1, and the other first mass addition film 4A is provided in the second edge region E2.

[0072] The first mass addition film 4A has a strip shape. Specifically, in a plan view, one first mass addition film 4A overlaps with the plurality of first electrode fingers 8A and the plurality of second electrode fingers 9A. More specifically, the first mass addition film 4A is provided over the piezoelectric substrate 2, the plurality of first electrode fingers 8A, and the plurality of second electrode fingers 9A. The first mass addition film 4A is provided continuously so as to overlap with the plurality of electrode fingers of the first IDT electrode 3A and the region between the electrode fingers in a plan view.

[0073] In this specification, the term "top view" refers to a view from the Figure 3 The elastic wave device is viewed from the upper direction. Figure 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 upper side.

[0074] like Figure 2 As shown, the width of each electrode finger of the first IDT electrode 3A in the portion overlapping with the first mass added 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 fixed. The width of the electrode finger is the dimension of the electrode finger along the direction orthogonal to the electrode finger.

[0075] In the first elastic wave resonator 1A, by providing the first mass addition film 4A in the first edge region E1, a low acoustic velocity region is formed in the first edge region E1. The so-called low acoustic velocity region in the first elastic wave resonator 1A is a region where the acoustic velocity is lower than the acoustic velocity in the first central region C1. Similarly, by providing the first mass addition film 4A in the second edge region E2, a low acoustic velocity region is formed in the second edge region E2. In addition, in the present embodiment, by increasing the width of the electrode fingers in the pair of edge regions, the acoustic velocity in the pair of edge regions is also reduced.

[0076] A pair of second mass addition films 4B are provided in a pair of edge regions of the second elastic wave resonator 1B. One second mass addition film 4B of the pair of second mass addition films 4B is provided in the third edge region E3, and the other second mass addition film 4B is provided in the fourth edge region E4.

[0077] A pair of second mass addition films 4B has a strip shape. Specifically, in a plan view, one second mass addition film 4B overlaps with a plurality of third electrode fingers 8B and a plurality of fourth electrode fingers 9B. More specifically, the second mass addition film 4B is provided over the piezoelectric substrate 2, the plurality of third electrode fingers 8B, and the plurality of fourth electrode fingers 9B. The second mass addition film 4B is provided continuously so as to overlap with a plurality of electrode fingers of the second IDT electrode 3B and the region between the electrode fingers in a plan view.

[0078] In the second elastic wave resonator 1B, the second mass addition film 4B is provided in the third edge region E3, so that a low acoustic velocity region is formed in the third edge region E3. The low acoustic velocity region in the second elastic wave resonator 1B is a region where the acoustic velocity is lower than the acoustic velocity in the second central region C2. Similarly, the second mass addition film 4B is provided in the fourth edge region E4, so that a low acoustic velocity region is formed in the fourth edge region E4.

[0079] In the first elastic wave resonator 1A, the first central region C1 and the pair of low acoustic velocity regions are arranged in this order from the center side in the direction in which the electrode fingers extend to the outside. In the second elastic wave resonator 1B, the second central region C2 and the pair of low acoustic velocity regions are arranged in this order from the center side in the direction in which the electrode fingers extend to the outside. Thus, a piston mode is established in each of the first elastic wave resonator 1A and the second elastic wave resonator 1B, and the transverse mode can be suppressed.

[0080] As the material of the first quality added film 4A and the second quality added film 4B, tantalum oxide such as Ta2O5 is used. However, the material of the first quality added film 4A and the second quality added film 4B is not limited to the above materials. Hereinafter, the first quality added film 4A and the second quality added film 4B may be simply described as quality added film.

[0081] like Figure 3 As shown, 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. Thus, a stack of the first IDT electrode 3A and the dielectric film 5 and a stack of the second IDT electrode 3B and the dielectric film 5 are formed.

[0082] 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 not easily damaged. In the present 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-mentioned materials. In addition, the dielectric film 5 may not be provided.

[0083] The present embodiment is characterized by having the following structures. 1) The thickness of the plurality of electrode fingers in the second IDT electrode 3B is thinner than the thickness of the plurality of 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) By Figure 4 As shown in an enlarged manner, the width of the electrode finger of the second IDT electrode 3B in the portion overlapping with the second mass added film 4B in a plan view is narrower than the width of the electrode finger in the second central region C2. This can more reliably suppress the transverse mode without reducing productivity. This is described below.

[0084] First, an example of a condition that can more reliably suppress the transverse mode is shown. This condition refers to the width W and thickness ratio T relative to the wavelength described later. R In a given range. Here, the wavelength specified by the electrode finger pitch is set to λ. The so-called electrode finger pitch refers to the distance in the orthogonal direction of the electrode fingers between the centers of adjacent electrode fingers connected to different potentials. The value obtained by dividing the dimension of the mass addition film along the electrode finger extension direction by the wavelength λ is set as the width W relative to the wavelength.

[0085] The value obtained by dividing the product of the density and thickness of each layer of the electrode finger by the density of Al is set as the Al-converted thickness of the layer. The total Al-converted thickness of each layer of the electrode finger is the Al-converted thickness of the electrode finger. For example, n is set as an arbitrary natural number, k is set as a natural number of 1≤k≤n, and the electrode finger has n layers. When the density of the kth electrode finger layer from the piezoelectric substrate 2 side is set as ρ k , set the thickness to t k , Set the Al conversion thickness to T k , and set the secret of Al to ρ Al When the Al conversion thickness of each layer of the electrode finger is T k T k ={(ρ k ·t k ) / ρ Al}. In addition, ρ Al 2.694 g / cm 3 . When the Al-converted thickness of the electrode finger is set to T IDT When Al is converted to thickness T IDT T IDT =∑{(ρ k ·T k ) / (ρ Al )}(1≤k≤n).

[0086] The value obtained by dividing the product of the density and thickness of the dielectric film 5 by the density of Al is defined as the Al-converted thickness of the dielectric film 5. d , set the thickness to t d , and the Al conversion thickness is set to T d When the Al conversion thickness T of the dielectric film 5 is d T d ={(ρ d ·t d ) / ρ Al}. Let the Al-converted thickness of the stack of electrode fingers and dielectric film 5 be T T .

[0087] The thickness of the mass-added film is set to t m , add the mass to the thickness of the film t m The Al-converted thickness T of the stack of the electrode fingers and the dielectric film 5 is T The thickness ratio is set as T R [%] Thickness ratio T R T R =(t m / T T )×100[%].

[0088] The transverse mode includes various modes such as the 1st to 11th order. R The relationship and scope are set to Figure 5 The relationship shown in FIG. 1 makes it possible to suppress the magnitude of the largest ripple among the ripples caused by the transverse mode in the frequency characteristics to 1 dB or less.

[0089] Figure 5 The width W and thickness ratio T of the mass-added film relative to the wavelength at which the magnitude of the ripple caused by the transverse mode becomes 1 dB or 0.1 dB are shown. R Graph of the relationship.

[0090] exist Figure 5 In the frequency characteristics of the elastic wave resonator, the solid line B1 shows the width W and the thickness ratio T relative to the wavelength at which the magnitude of the ripple caused by the transverse mode becomes 1 dB. R The width W and thickness ratio T relative to the wavelength within the range surrounded by the solid line B1 are R In the case of the combination of , the magnitude of the ripple caused by the transverse mode becomes less than 1 dB.

[0091] exist Figure 5 The range J is shown in FIG. The range J is within the range surrounded by the solid line B1. Specifically, the width W and the thickness ratio T relative to the wavelength at which the transverse mode is most suppressed are R The range of ±12% of the center of the combination is the range J. By the width W relative to the wavelength and the thickness ratio T R By setting the value within the range J, the magnitude of the ripple caused by the transverse mode can be further reliably suppressed to less than 1 dB.

[0092] In addition, Figure 5 In the middle, through the solid line B 0.1 The width W and thickness ratio T relative to the wavelength at which the size of the ripple caused by the transverse mode becomes 0.1 dB are shown. R By the width W relative to the wavelength and the thickness ratio T R The value of is represented by the solid line B 0.1 The values ​​within the enclosed range can suppress the magnitude of the ripple caused by the transverse mode to less than 0.1 dB.

[0093] Here, in first elastic wave resonator 1A, Figure 5 As shown, when the thickness ratio T R When the first mass added film 4A has a width W relative to the wavelength of 0.581λ or more and a thickness ratio T of 0.739λ or less, the width W relative to the wavelength is 10.7%. RThe value is within the range J. In this case, in first elastic wave resonator 1A, the transverse mode can be suppressed more reliably.

[0094] On the other hand, the thickness of the electrode fingers in second IDT electrode 3B of second elastic wave resonator 1B is thinner than the thickness of the electrode fingers in first IDT electrode 3A of first elastic wave resonator 1A. This makes it easier to increase the resonant frequency of second elastic wave resonator 1B. However, the thickness ratio T of second elastic wave resonator 1B is R This example is shown in Table 1.

[0095]

Table 1

[0096] First elastic wave resonator Second elastic wave resonator <![CDATA[Al conversion thickness T of the laminate of electrode fingers and dielectric films T > 175.8nm 135.8nm <![CDATA[The thickness t of the quality additional film m > 18.8nm 18.8nm <![CDATA[Thickness ratio T R ((t m / T T )×100)]]> 10.7％ 13.9％

[0097] In the example of Table 1, the Al-converted thickness of the stack of electrode fingers and dielectric film 5 in second elastic wave resonator 1B is thinner than the Al-converted thickness of the stack of electrode fingers and dielectric film 5 in first elastic wave resonator 1A. On the other hand, the thickness of the mass-added film is the same in first elastic wave resonator 1A and second elastic wave resonator 1B. Therefore, the thickness ratio T is greater in second elastic wave resonator 1B than in first elastic wave resonator 1A. R More specifically, in the example of Table 1, the thickness ratio T in the second elastic wave resonator 1B is R is 13.9%. Figure 5 The single-dot chain line in FIG.

[0098] In the example of Table 1, the thickness ratio T of the first elastic wave resonator 1A is R is 10.7%. Figure 5 As shown, in the first elastic wave resonator 1A, the width W of the first mass addition film 4A capable of suppressing the transverse mode is wide in range relative to the wavelength. On the other hand, the thickness ratio T of the second elastic wave resonator 1B is R In this case, by setting the width W of the second mass adding film 4B relative to the wavelength to Figure 5 The transverse mode can also be suppressed within the range of the width W relative to the wavelength shown in FIG. Figure 6 The first reference example shown and Figure 7 In the second reference example shown, the transverse mode can also be suppressed.

[0099] Specifically, in Figure 6 In the first reference example shown in FIG. 1 , 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 in the same manner as in the first embodiment. Figure 7In the second reference example shown, 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 fixed. In these cases, the width W of the second mass added film 4B relative to the wavelength is set to Figure 5 The width W of the second mass added film 4B with respect to the wavelength that can suppress the transverse mode may be within the range shown. However, the width W of the second mass added film 4B with respect to the wavelength that can suppress the transverse mode has a narrow range.

[0100] 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 Therefore, in the second elastic wave resonator 1B, the thickness ratio T R It is close to the value in the range J. However, in this case, in the manufacturing process, it is necessary to perform 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.

[0101] Here, the inventors of the present invention have found that the width of the portion of the electrode finger of the second IDT electrode 3B that overlaps with the second mass addition film 4B in a plan view is narrower than the width of the electrode finger in the second central region C2, thereby suppressing the range of the width W of the transverse mode relative to the wavelength from expanding. Specifically, even when the width W of the second mass addition film 4B relative to the wavelength is set to Figure 5 Even when the transverse mode is outside the range in which the transverse mode can be suppressed as shown, the transverse mode can be suppressed. More specifically, even when the width W of the second mass added film 4B relative to the wavelength is made narrower, the transverse mode can be suppressed.

[0102] As described above, in the elastic wave device 10 of the present embodiment, the thickness of the first mass addition film 4A and the thickness of the second mass addition film 4B are the same. In addition, the width of the electrode finger of the second IDT electrode 3B in the portion overlapping with the second mass addition film 4B in a plan view is narrower than the width of the electrode finger in the second central region C2. Thus, the range of the width W of the second mass addition film 4B that can suppress the transverse mode with respect to the wavelength can be expanded without complicating the manufacturing process. Therefore, the transverse mode can be suppressed more reliably without reducing productivity.

[0103] As in the present embodiment, in the first IDT electrode 3A, the width of the electrode finger in the portion overlapping with the first mass added film 4A in a plan view is preferably wider than the width of the electrode finger in the first central region C1 .

[0104] More specifically, for example, in order to lower the resonance frequency of the first elastic wave resonator 1A, the thickness of the electrode fingers of the first IDT electrode 3A may be made thicker. In this case, the range of the width W of the first mass addition film 4A that can suppress the transverse mode relative to the wavelength may be narrowed. On the other hand, in the present embodiment, the width of the electrode fingers of the first IDT electrode 3A in the portion overlapping with the first mass addition film 4A in a plan view is wider than the width of the electrode fingers in the first central region C1. Thus, in the first elastic wave resonator 1A, the range of the width W relative to the wavelength that can suppress the transverse mode can be widened. More specifically, even when the width W of the first mass addition film 4A relative to the wavelength is made wider, the transverse mode can be effectively suppressed.

[0105] When the thickness of the electrode fingers in the second IDT electrode 3B is reduced in order to increase the resonant frequency as in the second elastic wave resonator 1B, the thickness ratio T R However, if Figure 5 As shown, the thickness ratio T R In case of large thickness ratio T R Compared with a case where the mass addition film is smaller, the range of the width W of the transverse mode that can be suppressed by the mass addition film with respect to the wavelength is narrower. On the other hand, in the first embodiment of the present invention, in the second elastic wave resonator 1B, the range of the width W of the transverse mode that can be suppressed by the second mass addition film 4B with respect to the wavelength can be widened. Therefore, as a structure for suppressing the transverse mode without reducing productivity, the structure of the present invention is preferable.

[0106] The following is a further description of the structure of the first embodiment. Figure 2 As shown, a pair of gap regions are arranged between the first intersection region A1 of the first elastic wave resonator 1A and the pair of bus bars. The pair of gap regions are specifically 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.

[0107] In the first gap region G1, only the plurality of first electrode fingers 8A and the plurality of second electrode fingers 9A are provided. Thus, a high acoustic velocity region is formed in the first gap region G1. The so-called high acoustic velocity region in the first elastic wave resonator 1A refers to a region where the acoustic velocity is higher than the acoustic velocity in the first central region C1. The high acoustic velocity region is similarly formed in the second gap region G2.

[0108] The second elastic wave resonator 1B includes a third gap region G3 and a fourth gap region G4 as a pair of gap regions. 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 elastic wave resonator 1B, a high acoustic velocity region is formed in each of the third gap region G3 and the fourth gap region G4. The high acoustic velocity region in the second elastic wave resonator 1B refers to a region where the acoustic velocity is higher than the acoustic velocity in the second central region C2.

[0109] In the first elastic wave resonator 1A, the 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 the inside to the outside in the electrode finger extending direction. This makes it possible to further reliably suppress the transverse mode. In the second elastic wave resonator 1B, the 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 the inside to the outside in the electrode finger extending direction. This makes it possible to further reliably suppress the transverse mode.

[0110] In the first elastic wave resonator 1A of the first embodiment, each first mass addition film 4A is provided in each edge region. In addition, the first mass addition film 4A may be provided in at least one of the first edge region E1 and the second edge region E2. However, it is preferred that the first mass addition film 4A is provided in both the first edge region E1 and the second edge region E2. Thus, the transverse mode can be suppressed more reliably and effectively.

[0111] Similarly, in the second elastic wave resonator 1B, the second mass addition film 4B may be provided in at least one of the third edge region E3 and the fourth edge region E4. However, it is preferred that the second mass addition film 4B be provided in both the third edge region E3 and the fourth edge region E4. This can more reliably and effectively suppress the transverse mode.

[0112] like Figure 4 As shown, the tip of the fourth electrode finger 9B of the second IDT electrode 3B does not overlap with the second mass addition film 4B when viewed from above. The distance in the electrode finger extension direction between the tip of the fourth electrode finger 9B and the edge portion of the tip side of the fourth electrode finger 9B in the second mass addition film 4B located in the third edge region E3 when viewed from above is preferably 0.1λ or less. Similarly, when viewed from above, Figure 1 The distance between the tip of the third electrode finger 8B shown and the edge portion of the tip side of the third electrode finger 8B in the second mass added film 4B located in the fourth edge region E4 in the electrode finger extending direction is preferably 0.1λ or less. In addition, the tip of the electrode finger of the second IDT electrode 3B may overlap with the second mass added film 4B in a plan view.

[0113] On the other hand, the tip of the electrode finger of the first IDT electrode 3A overlaps with the first mass addition film 4A when viewed from above. However, the tip of the electrode finger of the first IDT electrode 3A may not overlap with the first mass addition film 4A when viewed from above. In this case, the distance in the electrode finger extension direction between the tip of the second electrode finger 9A and the edge portion on the tip side of the second electrode finger 9A in the first mass addition film 4A located in the first edge region E1 when viewed from above is preferably 0.1λ or less. The distance in the electrode finger extension direction between the tip of the first electrode finger 8A and the edge portion on the tip side of the first electrode finger 8A in the first mass addition film 4A located in the second edge region E2 when viewed from above is preferably 0.1λ or less.

[0114] like Figure 3 As shown in the figure, in the first elastic wave resonator 1A, the first electrode fingers 8A and the second electrode fingers 9A, the dielectric film 5, and the first mass addition film 4A are stacked in this order from the piezoelectric substrate 2 side. However, for example, the first mass addition film 4A, the electrode fingers, and the dielectric film 5 may be stacked in this order from the piezoelectric substrate 2 side. Alternatively, the first mass addition film 4A may be provided between the first electrode fingers 8A and the second electrode fingers 9A and the dielectric film 5.

[0115] In the second elastic wave resonator 1B, the third electrode fingers 8B and the fourth electrode fingers 9B, the dielectric film 5, and the second mass addition film 4B are stacked in this order from the piezoelectric substrate 2 side. However, for example, the second mass addition film 4B, the electrode fingers, and the dielectric film 5 may be stacked in this order from the piezoelectric substrate 2 side. Alternatively, the second mass addition film 4B may be provided between the third electrode fingers 8B and the fourth electrode fingers 9B and the dielectric film 5.

[0116] The piezoelectric substrate 2 of the elastic wave device 10 is a laminated substrate. Specifically, the piezoelectric substrate 2 includes a supporting 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 supporting 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.

[0117] In the first embodiment, lithium tantalate such as LiTaO 3 is used as the material of the piezoelectric layer 16. The material of the piezoelectric layer 16 is not limited to the above materials, and for example, lithium niobate, zinc oxide, aluminum nitride, quartz, or PZT (lead zirconate titanate) can also be used.

[0118] The low-acoustic-velocity film 15 is a film with a relatively low acoustic velocity. Specifically, the acoustic velocity of the body wave propagating in the low-acoustic-velocity film 15 is lower than the acoustic velocity of the body wave propagating in the piezoelectric layer 16. As the material of the low-acoustic-velocity film 15, for example, dielectrics such as glass, silicon oxide, silicon oxynitride, lithium oxide, tantalum oxide, or compounds in which fluorine, carbon, or boron is added to silicon oxide, or materials having the above materials as main components can be used. In this specification, the so-called main component refers to a component whose proportion exceeds 50wt%. The material of the above main component may also exist in any state of single crystal, polycrystalline, and amorphous, or in a state where they are mixed.

[0119] The high-acoustic-velocity film 14 is a film with a relatively high acoustic velocity. Specifically, the body wave propagating in the high-acoustic-velocity film 14 has a higher acoustic velocity than the elastic wave propagating in the piezoelectric layer 16. As the material of the high-acoustic-velocity film 14, for example, piezoelectrics such as aluminum nitride, lithium tantalate, lithium niobate, and quartz, alumina, sapphire, magnesium oxide, silicon nitride, silicon carbide, zirconium oxide, cordierite, mullite, steatite, forsterite, spinel, ceramics such as Sialon, dielectrics such as aluminum oxide, silicon oxynitride, DLC (diamond-like carbon), and diamond, or semiconductors such as silicon, or materials with the above materials as the main component can also be used. In addition, the above-mentioned spinel contains aluminum compounds containing one or more elements selected from Mg, Fe, Zn, Mn, etc. and oxygen. As examples of the above-mentioned spinel, MgAl2O4, FeAl2O4, ZnAl2O4, and MnAl2O4 can be listed.

[0120] As the material of the supporting substrate 13, for example, piezoelectrics such as aluminum nitride, lithium tantalate, lithium niobate, and quartz, ceramics such as alumina, sapphire, magnesium oxide, silicon nitride, silicon carbide, zirconium oxide, cordierite, mullite, steatite, and forsterite, dielectrics such as diamond and glass, semiconductors such as silicon and gallium nitride, or resins, or materials with the above materials as the main components can be used.

[0121] The high-acoustic-velocity film 14, the low-acoustic-velocity film 15, and the piezoelectric layer 16 are stacked in this order on the piezoelectric substrate 2. This allows the energy of the elastic wave to be effectively confined in the piezoelectric layer 16.

[0122] In addition, the stacked structure of the piezoelectric substrate is not limited to the above structure. For example, the piezoelectric substrate may also be a stacked substrate of a supporting substrate, a high acoustic velocity film, and a piezoelectric layer. Alternatively, the piezoelectric substrate may also have a high acoustic velocity supporting substrate made of the same material as the high acoustic velocity film. The sound velocity of the body wave propagating in the high acoustic velocity supporting substrate is higher than the sound velocity of the elastic wave propagating in the piezoelectric layer. In this case, the piezoelectric substrate may be a stacked substrate of a high acoustic velocity supporting substrate, a low acoustic velocity film, and a piezoelectric layer, or may be a stacked substrate of a high acoustic velocity supporting substrate and a piezoelectric layer. In these cases, the energy of the elastic wave can also be effectively confined on the piezoelectric layer side.

[0123] Table 2 shows examples of metal materials and dielectric materials, and the density of each material. Figure 3 The materials of the first IDT electrode 3A and the second IDT electrode 3B shown in FIG. 2 may also be the metals listed in Table 2. The dielectric film 5 may also be the dielectrics listed in Table 2. Furthermore, the first mass added film 4A and the second mass added film 4B may also be the dielectrics listed in Table 2. In addition, the metal material used for the first IDT electrode 3A and the second IDT electrode 3B, the dielectric film 5, the first mass added film 4A or the second mass added film 4B may also contain a small amount of a different material. For example, the Al layer may also contain a small amount of Cu.

[0124]

Table 2

[0125] <![CDATA[Density [g / cm 3 > Al 2.694 Ti 4.54 Cu 8.93 Ta 16.67 Au 19.3 Pt 21.37 Alumina 3.98 Silicon oxide 2.21 Germanium oxide 6.2 Tantalum Oxide 8.47

[0126] As described above, in the first embodiment, the first elastic wave resonator 1A and the second elastic 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 electrode. When the thicknesses of the electrode fingers 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 thickness of the electrode fingers is higher than the resonant frequency of the other surface acoustic wave resonator.

[0127] The inverse of the product of the electrode finger pitch, the duty ratio, and the thickness of the electrode fingers of the second IDT electrode 3B in the second elastic wave resonator 1B is preferably greater than the inverse of the product of the electrode finger pitch, the duty ratio, and the thickness of the electrode fingers of the first IDT electrode 3A in the first elastic wave resonator 1A. In this case, the resonant frequency of the second elastic wave resonator 1B is higher than the resonant frequency of the first elastic wave resonator 1A. In the first embodiment, the thickness of the plurality of electrode fingers in the second IDT electrode 3B is thinner than the thickness of the plurality of electrode fingers in the first IDT electrode 3A. Thus, the resonant frequency of the second elastic wave resonator 1B can be appropriately made higher than the resonant frequency of the first elastic wave resonator 1A.

[0128] Thus, the uses of the first filter device 10A including the first elastic wave resonator 1A and the second filter device 10B including the second elastic wave resonator 1B can be appropriately separated. The first filter device 10A can be appropriately used as a bandpass filter for a mid-frequency band, for example. The second filter device 10B can be appropriately used as a bandpass filter for a high-frequency band, for example.

[0129] In addition, the width of the portion of the electrode finger of the first IDT electrode 3A that overlaps with the first mass added film 4A in a plan view may not necessarily be wider than the width of the electrode finger in the first central region C1. Figure 8 In the modified example of the first embodiment shown in FIG. 1 , the width of the electrode fingers of the first IDT electrode 23A is constant. In this case, in the first elastic wave resonator, the thickness ratio T R The width W of the first mass added film 4A relative to the wavelength is preferably, for example, Figure 5 On the other hand, the width of the electrode finger of the second IDT electrode 3B in the portion overlapping with the second mass added film 4B in a plan view is narrower than the width of the electrode finger in the second central region C2. Thus, similarly to the first embodiment, the transverse mode can be suppressed more reliably without reducing productivity.

[0130] Fig. 9 1 is a schematic plan view of a first elastic wave resonator and a second elastic wave resonator according to the second embodiment. Fig.10 This is a schematic plan view showing, in an enlarged manner, the vicinity of one electrode finger of the first IDT electrode and the vicinity of one electrode finger of the second IDT electrode in the second embodiment.

[0131] This embodiment is different from the first embodiment in that a plurality of mass-added films are provided in each edge region. Except for the above-described point, the elastic wave device of this embodiment has the same structure as the elastic wave device 10 of the first embodiment.

[0132] A plurality of first mass addition films 34A are provided in the first edge region E1 of the first elastic wave resonator 1A. A plurality of first mass addition films 34A are also provided in the second edge region E2. One first mass addition film 34A overlaps with one electrode finger in a plan view. In the present embodiment, the first mass addition film 34A is provided only in a portion overlapping with the electrode finger in a plan view. However, the first mass addition film 34A may extend from a portion overlapping with the electrode finger in a plan view to a portion overlapping with a region between the electrode fingers in a plan view.

[0133] A plurality of second mass addition films 34B are provided in the third edge region E3 of the second elastic wave resonator 1B. A plurality of second mass addition films 34B are also provided in the fourth edge region E4. One second mass addition film 34B overlaps with one electrode finger in a plan view. In the present embodiment, the second mass addition film 34B is provided only in a portion overlapping with the electrode finger in a plan view. However, the second mass addition film 34B may extend from a portion overlapping with the electrode finger in a plan view to a portion overlapping with a region between the electrode fingers in a plan view.

[0134] In this embodiment, the width of the electrode finger of the second IDT electrode 3B in the portion overlapping the second mass added film 34B in plan view is also narrower than the width of the electrode finger in the second central region C2. Thus, similarly to the first embodiment, the transverse mode can be more reliably suppressed without reducing productivity.

[0135] In addition, the width of the portion of the electrode finger of the first IDT electrode 3A that overlaps with the first mass added film 34A in a plan view may not necessarily be wide. Fig.11 In the modified example of the second embodiment shown in FIG. 1 , the width of the electrode fingers of the first IDT electrode 23A is constant. In this case, in the first elastic wave resonator, the thickness ratio T R The width W of the first mass added film 34A relative to the wavelength is preferably, for example, Figure 5 On the other hand, the width of the electrode finger of the second IDT electrode 3B in the portion overlapping with the second mass added film 34B in a plan view is narrower than the width of the electrode finger in the second central region C2. Thus, similarly to the second embodiment, the transverse mode can be suppressed more reliably without reducing productivity.

[0136] The first mass additional film 34A does not contact the plurality of electrode fingers connected to different potentials. Similarly, the second mass additional film 34B does not contact the plurality of electrode fingers connected to different potentials. In this case, metal may be used as the material of the first mass additional film 34A and the second mass additional film 34B. However, a dielectric may be used as the material of the first mass additional film 34A and the second mass additional film 34B.

[0137] Fig.12 It is a schematic diagram of an elastic wave device according to a third embodiment.

[0138] The elastic wave device 40 of the present 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 an electrode pad or a wiring, for example.

[0139] 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 Figure 2 The first elastic wave resonator 1A shown in FIG. The second filter device 10B includes Figure 2 Therefore, similarly to the first embodiment, the transverse mode can be suppressed without reducing productivity.

[0140] Elastic wave device 40 may include at least one filter device other than first filter device 10A and second filter device 10B. This filter device may be connected to common connection terminal 45 together with first filter device 10A and second filter device 10B. The number of filter devices in elastic wave device 40 is not particularly limited.

[0141] In the present invention, first elastic wave resonator 1A and second elastic wave resonator 1B may be included in one bandpass filter.

[0142] Examples of aspects of the elastic wave device according to the present invention are summarized below.

[0143] <1> An elastic wave device comprises: a first elastic wave resonator having a piezoelectric substrate and a first IDT electrode including a plurality of electrode fingers disposed 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 disposed on the piezoelectric substrate, wherein in the first IDT electrode, when viewed from a direction perpendicular to the direction in which the plurality of electrode fingers extend, a region where the adjacent electrode fingers overlap each other is a first intersection region, and the first intersection 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 plurality of electrode fingers extend, and in the second IDT electrode, when viewed from a direction perpendicular to the direction in which the plurality of electrode fingers extend, a region where the adjacent electrode fingers overlap each other is a second intersection region, and the second intersection region has a second central region. The elastic wave device further comprises: a first mass addition film, which is provided in at least one of the first edge region and the second edge region and overlaps with the plurality of electrode fingers of the first IDT electrode in a plan view; and a second mass addition film, which is provided in at least one of the third edge region and the fourth edge region and overlaps with the plurality of electrode fingers of the second IDT electrode in a plan view, wherein the thickness of the plurality of electrode fingers in the second IDT electrode is thinner than the thickness of the plurality of electrode fingers in the first IDT electrode, the thickness of the first mass addition film is the same as the thickness of the second mass addition film, and 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.

[0144] <2> based on <1> In the elastic wave device described above, a width of the electrode finger of the first IDT electrode in a portion overlapping with the first mass addition film in a plan view is wider than a width of the electrode finger in the first central region.

[0145] <3> based on <1> or <2> The elastic wave device described, wherein, when the dimension of the first mass addition film along the direction in which the plurality of electrode fingers in the first IDT electrode extend is set as the width of the first mass addition film, and the dimension of the second mass addition film along the direction in which the plurality of electrode fingers in the second IDT electrode extend is set as the width of the second mass addition film, the width of the first mass addition film is wider than the width of the second mass addition film.

[0146] <4> based on <1> ~ <3> An elastic wave device as described in any one of the foregoing, wherein the first mass-added film is continuously arranged so as to overlap with the multiple electrode fingers of the first IDT electrode and the area between the electrode fingers when viewed from above, and the second mass-added film is continuously arranged so as to overlap with the multiple electrode fingers of the second IDT electrode and the area between the electrode fingers when viewed from above.

[0147] <5> based on <1> ~ <3> An elastic wave device as described in any one of the foregoing, wherein a plurality of the first mass additional films are arranged in at least one of the first edge region and the second edge region, and one of the first mass additional films is arranged to overlap with one of the electrode fingers of the first IDT electrode when viewed from above, and a plurality of the second mass additional films are arranged in at least one of the third edge region and the fourth edge region, and one of the second mass additional films is arranged to overlap with one of the electrode fingers of the second IDT electrode when viewed from above.

[0148] <6> based on <5> In the elastic wave device described above, metal is used as a material of the first mass added film and the second mass added film.

[0149] <7> based on <1> ~ <6> In the elastic wave device described in any one of , the first mass addition film is provided in both the first edge region and the second edge region, and the second mass addition film is provided in both the third edge region and the fourth edge region.

[0150] <8> based on <1> ~ <7> The elastic wave device according to any one of claims , wherein a resonant frequency of the second elastic wave resonator is higher than a resonant frequency of the first elastic wave resonator.

[0151] <9> based on <1> ~ <8> An elastic wave device as described in any one of the foregoing, comprising: a first filter device including the first elastic wave resonator; and a second filter device including the second elastic wave resonator, wherein the first filter device and the second filter device are connected to different signal potentials.

[0152] <10> based on <1> ~ <8> The elastic wave device described in any one of , comprising: a first filter device including the first elastic wave resonator; a second filter device including the second elastic wave resonator; and a common connection terminal that commonly connects the first filter device and the second filter device.

Claims

1. An elastic wave device comprising: A first elastic wave resonator including a piezoelectric substrate and a first IDT electrode including a plurality of electrode fingers disposed on the piezoelectric substrate; as well as a second elastic wave resonator which shares the piezoelectric substrate with the first elastic wave resonator and has a second IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate; In the first IDT electrode, when viewed from a direction orthogonal to the direction in which the plurality of electrode fingers extend, a region where adjacent electrode fingers overlap each other is a first intersection region, and the first intersection region includes 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 plurality of electrode fingers extend. In the second IDT electrode, when viewed from a direction orthogonal to the direction in which the plurality of electrode fingers extend, a region where adjacent electrode fingers overlap each other is a second intersection region, and the second intersection region includes 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 plurality of electrode fingers extend. The elastic wave device further comprises: a first mass added 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 plan view; as well as The second mass added film is provided in at least one of the third edge region and the fourth edge region and overlaps with the plurality of electrode fingers of the second IDT electrode in a plan view. The thickness of the plurality of electrode fingers in the second IDT electrode is thinner than the 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, A width of a portion of the electrode finger of the second IDT electrode that overlaps with the second mass added film in a plan view is narrower than a width of the electrode finger in the second central region.

2. The elastic wave device according to claim 1, wherein: The width of the electrode finger of the first IDT electrode in a portion overlapping with the first mass added film in a plan view is wider than the width of the electrode finger in the first central region.

3. The elastic wave device according to claim 1 or 2, wherein: When a dimension of the first mass addition film along a direction in which the plurality of electrode fingers in the first IDT electrode extend is set as a width of the first mass addition film, and a dimension of the second mass addition film along a direction in which the plurality of electrode fingers in the second IDT electrode extend is set as a width of the second mass addition film, the width of the first mass addition film is wider than the width of the second mass addition film.

4. The elastic wave device according to any one of claims 1 to 3, wherein: The first mass added film is continuously provided so as to overlap with the plurality of electrode fingers of the first IDT electrode and a region between the electrode fingers in a plan view. The second mass adding film is provided continuously so as to overlap with the plurality of electrode fingers of the second IDT electrode and a region between the electrode fingers in a plan view.

5. The elastic wave device according to any one of claims 1 to 3, wherein: A plurality of the first mass added films are provided in at least one of the first edge region and the second edge region, and one of the first mass added films is provided to overlap with one of the electrode fingers of the first IDT electrode in a plan 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, and one of the second mass adding films is provided so as to overlap with one of the electrode fingers of the second IDT electrode in a plan view.

6. The elastic wave device according to claim 5, wherein: Metal is used as a material of the first mass added film and the second mass added film.

7. The elastic wave device according to any one of claims 1 to 6, 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 elastic wave device according to any one of claims 1 to 7, wherein: The resonant frequency of the second elastic wave resonator is higher than the resonant frequency of the first elastic wave resonator.

9. The elastic wave device according to any one of claims 1 to 8, wherein: have: a first filter device including the first elastic wave resonator; and a second filter device including the second elastic wave resonator; The first filter device and the second filter device are connected to signal potentials different from each other.

10. The elastic wave device according to any one of claims 1 to 8, wherein: have: a first filter device comprising the first elastic wave resonator; a second filter device including the second elastic wave resonator; and The common connection terminal commonly connects the first filter device and the second filter device.

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