Elastic wave device, filter, duplexer, and multiplexer

Abstract

The purpose of the present invention is to improve resonance characteristics and filter characteristics. This elastic wave device comprises: a support substrate that contains single crystal silicon; an acoustic multilayer film that is provided on the upper side of the support substrate; a piezoelectric layer that is provided on the upper side of the acoustic multilayer film; and an IDT electrode that is provided on the upper side of the piezoelectric layer. The acoustic multilayer film has a first layer and a second layer made of a material different from that of the first layer. The IDT electrode has a first bus bar and a second bus bar that face each other, first electrode fingers, and second electrode fingers. When the thickness of the piezoelectric layer is d and the center-to-center distance between adjacent first and second electrode fingers is p, d / p is 0.5 or less. The plane orientation of the single crystal silicon on the principal surface of the support substrate on the piezoelectric layer side is the {100} plane. When the Euler angles of the support substrate are (φSi, θSi, ψSi) and n is an arbitrary integer, ψSi satisfies 19º + 90º × n ≤ ψSi ≤ 33° + 90° × n or 57° + 90° × n ≤ ψSi ≤ 71° + 90° × n.

Description

Acoustic wave apparatus, filters, duplexers and multiplexers

[0001] The present invention relates to acoustic wave devices, filters, duplexers, and multiplexers.

[0002] Patent Document 1 describes an elastic wave apparatus comprising an acoustic reflection layer having a low acoustic impedance layer and a high acoustic impedance layer having a higher acoustic impedance than the low acoustic impedance layer.

[0003] Patent No. 5648695

[0004] In the elastic wave apparatus shown in Patent Document 1, unwanted waves may be generated, potentially degrading the resonance characteristics and filter characteristics.

[0005] The present invention aims to provide elastic wave devices, filters, duplexers, and multiplexers that can improve resonance characteristics and filter characteristics.

[0006] An elastic wave apparatus according to one embodiment comprises a support substrate containing single-crystal silicon, an acoustic multilayer film provided on the upper side of the support substrate, a piezoelectric layer provided on the upper side of the acoustic multilayer film, and an IDT electrode provided on the upper side of the piezoelectric layer, wherein the acoustic multilayer film includes a first layer and a second layer made of a different material from the first layer, the IDT electrode has a first busbar facing each other, a second busbar, at least one first electrode finger whose base end is connected to the first busbar, and at least one second electrode finger whose base end is connected to the second busbar, the thickness of the piezoelectric layer is d, the distance between the centers of adjacent first electrode fingers and second electrode fingers is p, then d / p is 0.5 or less, the plane orientation of the single-crystal silicon on the main surface of the support substrate on the piezoelectric layer side is the {100} plane, and the Euler angle of the support substrate is (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ ), when n is any integer, the above ψ Ｓｉ This is 19° + 90° × n ≤ ψ Ｓｉ ≤33° + 90° × n or 57° + 90° × n ≤ψ Ｓｉ The condition satisfies ≤ 71° + 90° × n.

[0007] An elastic wave device according to another aspect includes a support substrate including single crystal silicon, an acoustic multilayer film provided on the upper side of the support substrate, a piezoelectric layer provided on the upper side of the acoustic multilayer film, and an IDT electrode provided on the upper side of the piezoelectric layer. The acoustic multilayer film includes a first layer and a second layer made of a material different from that of the first layer. The IDT electrode has a first bus bar and a second bus bar facing each other, at least one first electrode finger having a base end connected to the first bus bar, and at least one second electrode finger having a base end connected to the second bus bar. When the film thickness of the piezoelectric layer is d and the center-to-center distance between adjacent first and second electrode fingers is p, d / p is 0.5 or less. The plane orientation of the single crystal silicon on the main surface of the support substrate on the piezoelectric layer side is the {110} plane, and the Euler angles of the support substrate are (φ Ｓｉ , θ Ｓｉ , ψ Ｓｉ ). When n is an arbitrary integer, ψ Ｓｉ satisfies 0° + 180°×n ≤ ψ Ｓｉ ≤ 22° + 180°×n, 41° + 180°×n ≤ ψ Ｓｉ ≤ 85° + 180°×n, 95° + 180°×n ≤ ψ Ｓｉ ≤ 139° + 180°×n, or 160° + 180°×n ≤ ψ Ｓｉ ≤ 180° + 180°×n.

[0008] An elastic wave device according to another aspect includes a support substrate including single crystal silicon, an acoustic multilayer film provided on the upper side of the support substrate, a piezoelectric layer provided on the upper side of the acoustic multilayer film, and an IDT electrode provided on the upper side of the piezoelectric layer. The acoustic multilayer film includes a first layer and a second layer made of a material different from that of the first layer. The IDT electrode has a first bus bar and a second bus bar facing each other, at least one first electrode finger having a base end connected to the first bus bar, and at least one second electrode finger having a base end connected to the second bus bar. When the film thickness of the piezoelectric layer is d and the center-to-center distance between adjacent first and second electrode fingers is p, d / p is 0.5 or less. The plane orientation of the single crystal silicon on the main surface of the support substrate on the piezoelectric layer side is the {111} plane, and the Euler angles of the support substrate are (φ Ｓｉ , θ Ｓｉ , ψＳｉ ), when n is any integer, the above ψ Ｓｉ This is 17° + 120° × n ≤ ψ Ｓｉ ≤43° + 120° × n or 78° + 120° × n ≤ψ Ｓｉ The condition ≤ 103° + 120° × n is satisfied.

[0009] A filter according to one embodiment is a filter comprising a resonator, wherein at least one of the resonators is the elastic wave device.

[0010] A duplexer according to one embodiment has a signal terminal and two filters connected to the signal terminal, wherein at least one of the two filters is the aforementioned filter.

[0011] A multiplexer according to one embodiment has a signal terminal and a plurality of filters connected to the signal terminal, wherein at least one of the plurality of filters is the filter.

[0012] According to the elastic wave apparatus, filter, duplexer, and multiplexer of the present invention, resonance characteristics and filter characteristics can be improved.

[0013] Figure 1 is a plan view showing the elastic wave apparatus of the first embodiment. Figure 2 is a cross-sectional view taken along line II-II' of Figure 1. Figure 3 is an enlarged cross-sectional view showing region A shown in Figure 2. Figure 4 is a schematic cross-sectional view illustrating the bulk wave of the first-order thickness-slip mode propagating through the piezoelectric layer of the first embodiment. Figure 5 is a schematic cross-sectional view illustrating the amplitude direction of the bulk wave of the first-order thickness-slip mode propagating through the piezoelectric layer of the first embodiment. Figure 6 is an explanatory diagram showing an example of the resonance characteristics of the elastic wave apparatus of the first embodiment. Figure 7 is an explanatory diagram showing the relationship between d / 2p and the specific bandwidth as a resonator, where p is the distance between the centers of adjacent electrodes or the average distance between the centers, and d is the average thickness of the piezoelectric layer, in the elastic wave apparatus of the first embodiment. Figure 8 is a plan view showing an example in which a pair of electrodes are provided in the elastic wave apparatus of the first embodiment. Figure 9 is a reference diagram showing an example of the resonance characteristics of the elastic wave apparatus of the first embodiment. Figure 10 is an explanatory diagram showing the relationship between the relative bandwidth of the elastic wave apparatus of the first embodiment when a large number of elastic wave resonators are configured, and the phase rotation amount of the spurious impedance normalized by 180 degrees as the spurious magnitude. Figure 11 is an explanatory diagram showing the relationship between d / 2p, the metallization ratio MR, and the relative bandwidth. Figure 12 shows LiNbO when d / p approaches 0. ３ Euler angle (0°, θ) ＬＮ ψ ＬＮ This is an explanatory diagram showing a map of the relative bandwidth for ). Figure 13 is a schematic diagram showing the definition of the crystal axis of single-crystal silicon. Figure 14 is a schematic diagram showing the (100) plane of single-crystal silicon. Figure 15 is a plan view from the Z direction of the crystal axis of the main surface on the piezoelectric layer side of the support substrate according to the first embodiment. Figure 16 is the third component of the phase of the impedance of the elastic wave apparatus according to the first embodiment ψ Ｓｉ This figure shows a graph illustrating the dependence. Figure 17 is a graph showing the resonance characteristics for Example 1 and Comparative Example 1. Figure 18 is a schematic diagram showing the (110) plane of single-crystal silicon. Figure 19 is a plan view from the Z direction of the crystal axis of the main surface on the piezoelectric layer side of the support substrate according to the second embodiment. Figure 20 shows the third component ψ of the phase of the impedance of the elastic wave apparatus according to the second embodiment. ＳｉThis figure shows a graph illustrating the dependence. Figure 21 is a graph showing the resonance characteristics for Example 2 and Comparative Example 2. Figure 22 is a schematic diagram showing the (111) plane of single-crystal silicon. Figure 23 is a plan view from the Z direction of the crystal axis of the main surface on the piezoelectric layer side of the support substrate according to the third embodiment. Figure 24 shows the third component ψ of the phase of the impedance of the elastic wave apparatus according to the third embodiment. Ｓｉ Figure 25 is a graph showing the dependence. Figure 26 is a graph showing the resonance characteristics for Example 3 and Comparative Example 3. Figure 27 is a schematic circuit diagram of a filter according to the fourth embodiment. Figure 27 is a schematic circuit diagram of a duplexer according to the fifth embodiment. Figure 28 is a schematic diagram of a multiplexer according to the sixth embodiment.

[0014] Embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure. Each embodiment described in this disclosure is illustrative, and partial substitution or combination of configurations is possible between different embodiments. In modifications and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects and benefits due to similar configurations will not be mentioned sequentially for each embodiment.

[0015] (First Embodiment) Figure 1 is a plan view showing an elastic wave apparatus according to the first embodiment. Figure 2 is a cross-sectional view taken along line II-II' in Figure 1. Figure 3 is an enlarged cross-sectional view showing region A shown in Figure 2.

[0016] As shown in Figures 1 and 2, the elastic wave apparatus 10 according to the first embodiment includes a support member, a piezoelectric layer 20, an IDT electrode 30, and a dielectric layer 41.

[0017] (Support Member) In the first embodiment, the support member comprises a support substrate 11, an intermediate layer 12 provided on the upper side of the support substrate 11, and an acoustic multilayer film 43 provided on the upper side of the intermediate layer 12. That is, the intermediate layer 12 is provided between the support substrate 11 and the acoustic multilayer film 43. In the following description, one direction in the thickness direction of the support substrate 11 may be described as "up," and the other direction in the thickness direction of the support substrate 11 may be described as "down." In addition, in this disclosure, "provided on the upper side" includes being provided directly on top so as to be in contact with it, and being provided indirectly or at a distance so as to be located above it.

[0018] (Support Substrate) The support substrate 11 is made of silicon (Si). The support substrate 11 is preferably made of Si with a high resistivity of 4 kΩ or more. Details regarding the surface orientation of the support substrate 11 and the preferred range of Euler angles will be described later.

[0019] (Intermediate layer) The intermediate layer 12 is formed of a dielectric material. The material of the intermediate layer 12 is silicon oxide (SiO ｘ Preferably, the intermediate layer is made of ) and silicon nitride (SiN). Even when the intermediate layer 12 is provided, spurious emissions originating from the acoustic multilayer film 43 are more easily leaked to the support member, thus improving the resonance characteristics. Note that the intermediate layer 12 is not an essential component and may not be provided.

[0020] The acoustic multilayer film 43 has a laminated structure of first layers 43b, 43d, and 43f and second layers 43a, 43c, 43e, and 43g. The first layers 43b, 43d, and 43f have a relatively higher acoustic impedance than the second layers 43a, 43c, 43e, and 43g. This allows the bulk wave of the thickness-slip first mode to be confined within the piezoelectric layer 20. Note that the number of layers of the first layers 43b, 43d, and 43f and the second layers 43a, 43c, 43e, and 43g shown in Figure 2 is merely an example and is not particularly limited. It is sufficient that at least one of the first layers 43b, 43d, and 43f is located further from the piezoelectric layer 20 than the second layers 43a, 43c, 43e, and 43g.

[0021] The first layers 43b, 43d, and 43f are, for example, tungsten carbide (WC), tantalum carbide (TaC), rhenium oxide (ReO). ３), carbon silicon chromium (CrCSI), niobium carbide (NbC), zinc carbide (ZrC), zinc nitride (TiC), lanthanum boride (LaB ６ ), vanadium carbide (VC), aluminum nitride (AlN), silicon carbide (SiC), yttrium oxide (Y ２ O ３ ), magnesium oxide (MgO), silicon nitride (Si ３ N ４ ), boron carbide (B ４ C), Strontium fluoride (SrF ２ ), barium fluoride (BaF ２ ), tantalum oxide (Ta ２ O ５ ), hafnium oxide (HfO ２ ), tungsten oxide (WO ３ Preferably, the second layer 43a, 43c, 43e, 43g contains, for example, silicon dioxide (SiO₂). ｘ Preferably, the material contains at least one of ) and aluminum (Al). In the first embodiment, the first layers 43b, 43d, 43f and the second layers 43a, 43c, 43e, 43g are formed of a different material from the dielectric layer 41. Furthermore, the second layers 43a, 43c, 43e, 43g and the intermediate layer 12 are all silicon oxide (SiO₂). ｘ If the second layer 43a, 43c, 43e, 43g consists of silicon oxide (SiO₂) with a lower density than the intermediate layer 12. ｘ Preferably, the layers consist of the materials described above. However, the materials for the first layers 43b, 43d, 43f and the second layers 43a, 43c, 43e, 43g are not limited to those described above. As long as the acoustic impedance relationship described above is satisfied, the layers can be made of any suitable material. For example, the materials for the first layers 43b, 43d, 43f may be different from each other, and the materials for the second layers 43a, 43c, 43e, 43g may be different from each other. Furthermore, the materials for the first layers 43b, 43d, 43f and the second layers 43a, 43c, 43e, 43g are not limited to a single type of material, but may be layers of a mixture containing multiple materials.

[0022] The piezoelectric layer 20 is a flat plate-shaped layer provided on the upper side of the support member. The piezoelectric layer 20 has a first main surface 20a which is the upper surface and a second main surface 20b which is the lower surface. The piezoelectric layer 20 is made of lithium niobate (LiNbO ３ ) is formed of ). Alternatively, the piezoelectric layer 20 is lithium tantalate (LiTaO ３ ) may consist of . LiNbo ３ ya LiTaO ３ The cut angle is, for example, a Z-cut. LiNbO ３ ya LiTaO ３ The cut angle may be a rotational Y-cut or an X-cut, and a propagation direction of ±30° for Y propagation and X propagation is preferred. The piezoelectric layer 20 is lithium niobate (LiNbO ３ ) or lithium tantalate (LiTaO) ３ It is preferable that the cut is a 120°±10° rotation Y-cut or a 90°±10° rotation Y-cut. Here, 120°±10° includes the range of 120°-10° or more and 120°+10° or less, and 90°±10° includes the range of 90°-10° or more and 90°+10° or less.

[0023] The thickness of the piezoelectric layer 20 is not particularly limited, but to effectively excite the thickness-sliding primary mode, it is preferably 50 nm to 1000 nm. The thickness of the piezoelectric layer 20 according to the first embodiment is, for example, about 180 nm.

[0024] (IDT electrode) The IDT (Interdigital Transducer) electrode 30 is provided on the upper side of the piezoelectric layer 20. That is, the IDT electrode 30 may be provided directly on the first main surface 20a, or it may be provided indirectly on the first main surface 20a via a dielectric layer or the like. In the first embodiment, the IDT electrode 30 is provided directly on the first main surface 20a.

[0025] As shown in Figure 1, the IDT electrode 30 has a first electrode finger 31, a second electrode finger 32, a first busbar 33, and a second busbar 34. The multiple first electrode fingers 31 extend in the Y direction, and one end in the extending direction is connected to the first busbar 33. The multiple second electrode fingers 32 extend in the Y direction, and the other end in the extending direction is connected to the second busbar 34. The multiple first electrode fingers 31 and the multiple second electrode fingers 32 are arranged alternately in the X direction with spacing between them. The first busbar 33 and the second busbar 34 each extend in the X direction and are arranged opposite each other in the Y direction. The multiple first electrode fingers 31 and the multiple second electrode fingers 32 are arranged between the first busbar 33 and the second busbar 34.

[0026] Furthermore, the IDT electrode 30 is not limited to a configuration having a plurality of first electrode fingers 31 and a plurality of second electrode fingers 32, and may also include a configuration with at least one first electrode finger 31 whose base end is connected to a first busbar 33 and at least one second electrode finger 32 whose base end is connected to a second busbar 34.

[0027] In the following description, the thickness direction of the piezoelectric layer 20 may be referred to as the Z direction, the extension direction of the first electrode finger 31 and the second electrode finger 32 as the Y direction, and the arrangement direction of the first electrode finger 31 and the second electrode finger 32 as the X direction. In the first embodiment, the X direction is perpendicular to the extension direction of the first electrode finger 31 and the second electrode finger 32. Also, in the following description, "up" refers to the direction from the support substrate 11 toward the piezoelectric layer 20, and "down" refers to the direction from the piezoelectric layer 20 toward the support substrate 11.

[0028] The distance between the centers of the first electrode finger 31 and the second electrode finger 32 (electrode pitch) is not particularly limited, but is preferably in the range of 1 μm to 10 μm. Here, the electrode pitch refers to the distance between the center line of the dimensions of the first electrode finger 31 in the direction perpendicular to the extending direction (Y direction) of the first electrode finger 31 (X direction) and the center line of the dimensions of the second electrode finger 32 in the direction perpendicular to the extending direction (Y direction) of the second electrode finger 32 (X direction). In addition, the width of the first electrode finger 31 and the second electrode finger 32 (electrode width), that is, the dimensions in the direction perpendicular to the extending direction (Y direction) of the first electrode finger 31 and the second electrode finger 32 (X direction), is not particularly limited, but is preferably in the range of 150 nm to 1000 nm.

[0029] When there are multiple first electrode fingers 31 and second electrode fingers 32, that is, when the first electrode fingers 31 and second electrode fingers 32 are considered as a pair of electrode sets, there are 1.5 or more pairs of electrode sets, the arithmetic mean of the center-to-center distances of adjacent first electrode fingers 31 and second electrode fingers 32 among the 1.5 or more pairs of first electrode fingers 31 and second electrode fingers 32 may be described as the average center-to-center distance between the first electrode fingers 31 and second electrode fingers 32 (average electrode pitch).

[0030] In the first embodiment, the electrode spacing between electrode pairs consisting of a first electrode finger 31 and a second electrode finger 32 was made equal for all pairs. That is, the first electrode finger 31 and the second electrode finger 32 were arranged at equal pitches.

[0031] In the first embodiment, the IDT electrode 30, i.e., the first electrode finger 31, the second electrode finger 32, the first busbar 33, and the second busbar 34, is made of a suitable metal or alloy such as Al or AlCu alloy. Alternatively, the IDT electrode 30 may be a laminate in which an Al film is laminated on an adhesion layer such as a titanium (Ti) film. Note that an adhesion layer other than a Ti film may also be used.

[0032] Here, the crossing region C (excitation region) shown in Figure 1 is the region where the first electrode finger 31 and the second electrode finger 32 overlap when viewed in the X direction. The length of the crossing region C is the dimension in the extending direction of the first electrode finger 31 and the second electrode finger 32 in the crossing region C. In this embodiment, the length of the crossing region C is, for example, 30 μm.

[0033] During operation, an AC voltage is applied between a plurality of first electrode fingers 31 and a plurality of second electrode fingers 32. More specifically, an AC voltage is applied between a first busbar 33 and a second busbar 34. This makes it possible to obtain resonance characteristics using the bulk wave of the thickness-slip first mode excited in the piezoelectric layer 20.

[0034] Furthermore, in the elastic wave apparatus 10, when the thickness of the piezoelectric layer 20 is d and the average electrode pitch is p, d / p is set to 0.5 or less. Therefore, the bulk wave of the thickness-slip first mode described above is effectively excited, and good resonance characteristics can be obtained. More preferably, d / p is 0.24 or less, in which case even better resonance characteristics can be obtained. Regarding the thickness d of the piezoelectric layer 20, if the piezoelectric layer 20 has thickness variations, the average value of its thickness is adopted.

[0035] In the elastic wave apparatus 10 of the first embodiment, because it has the above configuration, propagation loss is low, and even if the logarithm of the first electrode finger 31 and the second electrode finger 32 is reduced in an attempt to miniaturize the device, a decrease in the Q value is unlikely to occur. This is because it utilizes a bulk wave of the first-order mode of thickness sliding.

[0036] (Dielectric layer) The dielectric layer is a dielectric layer provided on at least one main surface of the piezoelectric layer 20. In the first embodiment, the dielectric layer 41 is provided on the first main surface 20a. This makes it possible to suppress higher-order modes that occur in the thickness direction of the piezoelectric layer 20 and improve the resonance characteristics.

[0037] In the examples shown in Figures 2 and 3, the dielectric layer 41 is provided so as to cover the IDT electrode 30 provided on the first main surface 20a. That is, the IDT electrode 30 is provided in the Z direction between the dielectric layer 41 and the first main surface 20a of the piezoelectric layer 20.

[0038] The material of the dielectric layer 41 is not particularly limited, and for example, silicon dioxide (SiO₂ ｘ ), silicon nitride (Si ３ N ４ ), aluminum nitride (AlN), aluminum oxide (Al ２ O ３ ), tantalum oxide (Ta ２ O ５ ), niobium oxide (Nb ２ O ５ It may be at least one of the following. Also, the dielectric layer 41 may be made up of multiple layers stacked together.

[0039] Figure 4 is a schematic cross-sectional view illustrating the bulk wave of the first-order thickness-slip mode propagating through the piezoelectric layer of the first embodiment. Figure 5 is a schematic cross-sectional view illustrating the amplitude direction of the bulk wave of the first-order thickness-slip mode propagating through the piezoelectric layer of the first embodiment.

[0040] As shown in Figure 4, in the elastic wave device 10 of the first embodiment, since the vibration displacement is in the thickness sliding direction, the wave propagates almost entirely in the direction connecting the first main surface 20a and the second main surface 20b of the piezoelectric layer 20, i.e., in the Z direction, and resonates. That is, the X-direction component of the wave propagation direction is significantly smaller than the Z-direction component. And since the resonance characteristics are obtained by the propagation of this wave in the Z direction, a reflector is not required. Therefore, no propagation loss occurs when the wave propagates to the reflector. Accordingly, even if the number of logarithms of electrode pairs consisting of the first electrode finger 31 and the second electrode finger 32 is reduced in an attempt to miniaturize the device, a decrease in the Q value is unlikely to occur.

[0041] In the first embodiment, the amplitude direction of the bulk wave in the thickness-slip primary mode is approximately opposite in the first region 251 and the second region 252, both included in the intersection region C (see Figure 1) of the piezoelectric layer 20, as shown in Figure 5. Figure 5 schematically shows the bulk wave when a voltage is applied between the first electrode finger 31 and the second electrode finger 32 such that the second electrode finger 32 is at a higher potential than the first electrode finger 31. Here, the virtual plane VP1 is a plane that is perpendicular to the thickness direction of the piezoelectric layer 20 and divides the piezoelectric layer 20 into two. The first region 251 is the region between the virtual plane VP1 and the first main surface 20a within the intersection region C. The second region 252 is the region between the virtual plane VP1 and the second main surface 20b within the intersection region C.

[0042] In the elastic wave device 10, at least one pair of electrodes consisting of a first electrode finger 31 and a second electrode finger 32 are arranged. However, since waves are not propagated in the X direction, it is not necessarily required that there be multiple pairs of electrodes consisting of the first electrode finger 31 and the second electrode finger 32. In other words, it is sufficient that at least one pair of electrodes is provided.

[0043] For example, the first electrode finger 31 is an electrode connected to a hot potential, and the second electrode finger 32 is an electrode connected to a ground potential. However, the first electrode finger 31 may be connected to a ground potential and the second electrode finger 32 may be connected to a hot potential. In the first embodiment, at least one pair of electrodes are either connected to a hot potential or to a ground potential, as described above, and no floating electrodes are provided.

[0044] Figure 6 is an explanatory diagram showing an example of the resonance characteristics of the elastic wave apparatus of the first embodiment. The design parameters of the elastic wave apparatus 10 that obtained the resonance characteristics shown in Figure 6 are as follows.

[0045] Piezoelectric layer 20: LiNbO with Euler angles (0°, 0°, 90°) ３ Piezoelectric layer 20 thickness: 400 nm Support substrate 11: Si Length of cross region C: 40 μm Number of electrode pairs consisting of first electrode finger 31 and second electrode finger 32: 21 pairs Pitch between first electrode finger 31 and second electrode finger 32: 3 μm Width of first electrode finger 31 and second electrode finger 32: 500 nm d / p: 0.133

[0046] As is clear from Figure 6, good resonance characteristics with a relative bandwidth of 12.5% ​​are obtained despite the absence of a reflector.

[0047] By the way, if the thickness of the piezoelectric layer 20 is d and the average (average distance) of the electrode pitch between the first electrode finger 31 and the second electrode finger 32 is p, then in the first embodiment, d / p is 0.5 or less, more preferably 0.24 or less. This will be explained with reference to Figure 7.

[0048] Figure 7 is an explanatory diagram showing the relationship between d / 2p and the specific bandwidth of the resonator in the elastic wave apparatus of the first embodiment, where p is the distance between the centers of adjacent electrodes or the average distance between the centers, and d is the average thickness of the piezoelectric layer. In Figure 7, multiple elastic wave apparatuses were obtained in the same manner as the elastic wave apparatus that obtained the resonance characteristics shown in Figure 6, except that d / 2p was changed.

[0049] As shown in Figure 7, when d / 2p exceeds 0.25, i.e., d / p > 0.5, the relative bandwidth is less than 5% even when d / p is adjusted. In contrast, when d / 2p ≤ 0.25, i.e., d / p ≤ 0.5, the relative bandwidth can be increased to 5% or more by changing d / p within that range, i.e., a resonator with a high coupling coefficient can be constructed. Furthermore, when d / 2p is 0.12 or less, i.e., when d / p is 0.24 or less, the relative bandwidth can be increased to 7% or more. In addition, by adjusting d / p within this range, a resonator with an even wider relative bandwidth can be obtained, and a resonator with an even higher coupling coefficient can be realized. Therefore, it can be seen that by setting d / p to 0.5 or less, a resonator with a high coupling coefficient can be constructed using the bulk wave of the thickness-slip first mode described above.

[0050] Figure 8 is a plan view showing an example in which a pair of electrodes is provided in the elastic wave apparatus of the first embodiment. In the elastic wave apparatus 10, a pair of electrodes having a first electrode finger 31 and a second electrode finger 32 are provided on the first main surface 20a of the piezoelectric layer 20. In Figure 8, K is the crossover width. As mentioned above, in the elastic wave apparatus 10 of this disclosure, the number of electrode finger pairs may be one. Even in this case, if the above d / p is 0.5 or less, the bulk wave of the thickness-slip first mode can be effectively excited.

[0051] In the elastic wave apparatus 10, it is preferable that the metallization ratio MR of the adjacent first electrode finger 31 and second electrode finger 32 with respect to the crossing region C satisfies MR ≤ 1.75 (d / p) + 0.075. In this case, spurious emissions can be effectively reduced. This will be explained with reference to Figures 8 and 9.

[0052] Figure 9 is a reference diagram showing an example of the resonance characteristics of the elastic wave apparatus of the first embodiment. As shown in Figure 9, the spurious signal indicated by arrow B appears between the resonant frequency and the anti-resonant frequency. Note that d / p = 0.08 and LiNbO ３ The Euler angles were set to (0°, 0°, 90°). Furthermore, the metallization ratio MR was set to 0.35.

[0053] The metallization ratio MR will be explained with reference to Figure 1. In the electrode structure of Figure 1, if we focus on a pair of first electrode fingers 31 and second electrode fingers 32, we assume that only this pair of first electrode fingers 31 and second electrode fingers 32 are provided. In this case, the area enclosed by the dashed line becomes the intersection region C. This intersection region C is the area on the first electrode finger 31 that overlaps with the second electrode finger 32 when viewed in a direction perpendicular to the extending direction of the first electrode finger 31 and the second electrode finger 32, i.e., in an opposing direction, the area on the first electrode finger 31 that overlaps with the first electrode finger 32, the area on the second electrode finger 32 that overlaps with the first electrode finger 31, and the area between the first electrode finger 31 and the second electrode finger 32 that overlaps. The area of ​​the first electrode finger 31 and the second electrode finger 32 within the intersection region C relative to the area of ​​the intersection region C is the metallization ratio MR. In other words, the metallization ratio MR is the ratio of the area of ​​the metallized portion to the area of ​​the cross region C.

[0054] Furthermore, if multiple pairs of first electrode fingers 31 and second electrode fingers 32 are provided, the ratio of the metallized portion to the total area of ​​the crossing region C should be defined as MR.

[0055] Figure 10 is an explanatory diagram showing the relationship between the relative bandwidth of the elastic wave device of the first embodiment, when a large number of elastic wave resonators are configured, and the phase rotation amount of the spurious impedance normalized to 180 degrees as the spurious magnitude. The relative bandwidth was adjusted by changing various aspects of the thickness of the piezoelectric layer 20 and the dimensions of the first electrode fingers 31 and the second electrode fingers 32. Also, Figure 10 shows the Z-cut LiNbO ３ The results shown are for the case where a piezoelectric layer 20 consisting of the above is used, but a similar trend is observed when piezoelectric layers 20 with other cut angles are used.

[0056] In the region enclosed by the ellipse J in Figure 10, the spurious emission is large at 1.0. As is clear from Figure 10, when the relative bandwidth exceeds 0.17, that is, when it exceeds 17%, large spurious emissions with a spurious emission level of 1 or more appear within the passband, even if the parameters constituting the relative bandwidth are changed. In other words, as shown in the resonance characteristics in Figure 8, large spurious emissions indicated by arrow B appear within the bandwidth. Therefore, it is preferable that the relative bandwidth be 17% or less. In this case, the spurious emissions can be reduced by adjusting the thickness of the piezoelectric layer 20 and the dimensions of the first electrode finger 31 and the second electrode finger 32.

[0057] Figure 11 is an explanatory diagram showing the relationship between d / 2p, the metallization ratio MR, and the relative bandwidth. In the elastic wave apparatus 10 of the first embodiment, various elastic wave apparatuses 10 with different d / 2p and MR were configured and the relative bandwidth was measured. The hatched area to the right of the dashed line D in Figure 11 is the region where the relative bandwidth is 17% or less. The boundary between this hatched region and the unhatched region is represented by MR = 3.5(d / 2p) + 0.075. That is, MR = 1.75(d / p) + 0.075. Therefore, preferably, MR ≤ 1.75(d / p) + 0.075. In that case, it is easy to keep the relative bandwidth at 17% or less. More preferably, it is the region to the right of MR = 3.5(d / 2p) + 0.05, shown by the dashed line D1 in Figure 11. In other words, if MR ≤ 1.75 (d / p) + 0.05, the relative bandwidth can be reliably reduced to 17% or less.

[0058] Figure 12 shows the LiNbO2 when d / p approaches 0. ３ Euler angle (0°, θ) ＬＮ ψ ＬＮ This is an explanatory diagram showing a map of the relative bandwidth for ). The hatched area in Figure 12 is the region where a relative bandwidth of at least 5% is obtained. Approximating the range of the region, it is the range expressed by the following equations (1), (2), and (3).

[0059] (0°±10°, 0°~20°, any ψ) ＬＮ )...Equation (1) (0°±10°, 20°~80°, 0°~60°(1-(θ ＬＮ -50)２ / 900) １／２ ) or (0°±10°, 20°~80°, [180°-60°(1-(θ) ＬＮ -50) ２ / 900) １／２ ]~180°) ...Equation (2) (0°±10°, [180°−30°(1−(ψ ＬＮ -90) ２ ( / 8100) １／２ ] ~180°, any ψ ＬＮ ) ...Formula (3)

[0060] Therefore, in the case of the Euler angle range of equation (1), equation (2), or equation (3) above, the relative bandwidth can be made sufficiently wide, which is preferable.

[0061] The following provides a detailed explanation of the plane orientation and Euler angle of the support substrate 11. Figure 13 is a schematic diagram showing the definition of the crystal axis of single-crystal silicon. Figure 14 is a schematic diagram showing the (100) plane of single-crystal silicon.

[0062] In the first embodiment, the support substrate 11 is a single-crystal silicon substrate. As shown in Figure 13, the crystal structure of the single-crystal silicon has a diamond structure (space group: Fd-3m). In the following description, the coordinate system aligned with the crystal axis of the single-crystal silicon of the support substrate 11 (crystal space coordinate system) is referred to as (X Ｓｉ , Y Ｓｉ , Z Ｓｉ It is sometimes explained as follows. For more details, see X Ｓｉ Axis direction, Y Ｓｉ Axial and Z Ｓｉ Each of the axial directions refers to the direction of the crystal axis, represented by the Miller indices

[100] ,

[010] , and

[001] of single-crystal silicon, respectively. In single-crystal silicon, due to the geometric symmetry of the diamond structure, X Ｓｉ Axis, Y Ｓｉ Axis and Z Ｓｉ The axes are crystallinely equivalent.

[0063] In the first embodiment, the plane orientation of the single crystal silicon on the main surface 11a of the support substrate 11 on the piezoelectric layer 20 side is {100}. In the present disclosure, that the plane orientation is {khl} means that it is a (khl) plane orthogonal to the crystal axis represented by the Miller index [khl] or a crystal plane that is crystallographically equivalent to the (khl) plane. Here, since each crystal axis (X Ｓｉ axis, Y Ｓｉ axis, and Z Ｓｉ axis) of the single crystal silicon is equivalent, the plane orientation {100} of the single crystal silicon is not limited to the (100) plane shown in FIG. 14, and includes crystal planes that are crystallographically equivalent to the (100) plane, such as the (010) plane and the (001) plane. Here, the crystal axis direction of the single crystal silicon can be determined by X-ray diffraction measurement with respect to the cross section of the support substrate 11 along the Z direction.

[0064] FIG. 15 is a plan view of the crystal axis of the main surface on the piezoelectric layer side of the support substrate according to the first embodiment viewed from the Z direction. In FIG. 15, the crystal axes of the single crystal silicon when the main surface 11a of the support substrate 11 is the (100) plane of the single crystal silicon are shown. As shown in FIG. 15, in the first embodiment, the crystal axes of the main surface 11a of the support substrate 11 have four-fold rotational symmetry in the plane, and a crystal structure equivalent to that obtained by rotating 90° around the Z axis is obtained. Here, the rotational symmetry of the crystal axis of the single crystal silicon of the support substrate 11 according to the first embodiment viewed from the Z direction is the same even when the main surface 11a of the support substrate 11 is a plane equivalent to the (100) plane of the single crystal silicon, such as the (010) plane or the (001) plane.

[0065] In the present disclosure, that the Euler angles are (φ, θ, ψ) means that the coordinate system (x3, y3, z3) obtained by rotating the coordinate system (x, y, z) aligned with the crystal axis in the order of the following procedure (A), procedure (B), and procedure (C) coincides with the space coordinate system (X, Y, Z). Here, the positive rotation direction is defined as the counterclockwise rotation direction when viewed from the positive direction of the rotation axis. Also, the crystal space coordinate system (X Ｓｉ , Y Ｓｉ , Z ＳｉEach of them corresponds to each of the coordinate systems (x, y, z) aligned with the crystal axes described above. In the following description, φ may be described as the first component, θ as the second component, and ψ as the third component. (A) Rotate the x-axis by the rotation angle of the magnitude of the first component φ about the z-axis as the rotation axis. Thereby, the rotated coordinate system (x1, y1, z1) is defined. Here, since the z-axis does not rotate, the z1-axis has the same direction as the z-axis. (B) Rotate the z1-axis by the rotation angle of the magnitude of the second component θ about the x1-axis as the rotation axis. Thereby, the rotated coordinate system (x2, y2, z2) is defined. Here, since the x1-axis does not rotate, the x2-axis has the same direction as the x1-axis. (C) Rotate the x2-axis by the rotation angle of the magnitude of the third component ψ about the z2-axis as the rotation axis. Thereby, the rotated coordinate system (x3, y3, z3) is defined. Here, since the z2-axis does not rotate, the z3-axis has the same direction as the z2-axis.

[0066] In the "Handbook of Elastic Wave Element Technology" (edited by the 150th Committee on Elastic Wave Element Technology of the Japan Society for the Promotion of Science, First Edition, First Printing, issued on November 30, 1991, Ohmsha, 549 pages), the definition of the right-handed Euler angles is described. In the present disclosure, the definition of the right-handed Euler angles described in the said document is incorporated.

[0067] The inventor of the elastic wave device according to the present disclosure has found that the deterioration of the resonance characteristics in the elastic wave device including the acoustic multilayer film 43 is caused by the unnecessary waves of the bulk waves derived from the acoustic multilayer film 43. From this, as a result of intensive research, the inventor has set the plane orientation of the main surface 11a of the support substrate 11 as a predetermined crystal plane, and the third component ψ of the Euler angles of the support substrate 11 Ｓｉ is within a predetermined range, so that the unnecessary waves of the bulk waves by the acoustic multilayer film 43 can be leaked to the support substrate 11, and the resonance characteristics can be improved.

[0068] In the first embodiment, the first component φ of the Euler angles of the support substrate 11 Ｓｉ and the second component θ Ｓｉ are appropriately selected so that the plane orientation of the main surface 11a becomes the {100} plane. For example, φ Ｓｉ = 90° and θ Ｓｉ = 90°. The third component ψ Ｓｉ is 19° ≤ ψ Ｓｉ≤39° or 51°≤ψ Ｓｉ The condition ≤71° is satisfied. By keeping it within this range, unwanted bulk waves originating from the acoustic multilayer film 43 are more likely to leak to the support substrate 11, thereby suppressing the containment of unwanted waves in the piezoelectric layer 20 and improving the resonance characteristics.

[0069] In the first embodiment, as described above, the crystal axis of the single-crystal silicon of the support substrate 11 is rotationally symmetric four times in the Z direction when viewed in plan, so the Euler angle (φ) of the single-crystal silicon of the support substrate 11 Ｓｉ , θ Ｓｉ ψ Ｓｉ ) and (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ The expression (+90° × n) is equivalent for any integer n (=0, ±1, ±2, ...). Therefore, in the first embodiment, the third component ψ of the Euler angle of the support substrate 11 is Ｓｉ This is 19° + 90° × n ≤ ψ Ｓｉ ≤39° + 90° × n or 51° + 90° × n ≤ψ Ｓｉ The value must be ≤71° + 90° × n.

[0070] As described above, the elastic wave apparatus 10 according to the first embodiment comprises a support substrate 11 containing single-crystal silicon, an acoustic multilayer film 43 provided on the upper side of the support substrate 11, a piezoelectric layer 20 provided on the upper side of the acoustic multilayer film 43, and an IDT electrode 30 provided on the upper side of the piezoelectric layer 20. The acoustic multilayer film 43 includes a first layer and a second layer made of a different material from the first layer. The IDT electrode 30 has a first busbar 33 facing each other, a second busbar 34, at least one first electrode finger 31 whose base end is connected to the first busbar 33, and at least one second electrode finger 32 whose base end is connected to the second busbar 34. When the thickness of the piezoelectric layer 20 is d and the distance between the centers of adjacent first electrode fingers 31 and second electrode fingers 32 is p, d / p is 0.5 or less. The plane orientation of the single-crystal silicon on the main surface 11a of the support substrate 11 on the piezoelectric layer 20 side is the {100} plane. The Euler angle of the support substrate 11 is (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ ), when n is any integer, ψ Ｓｉ This is 19° + 90° × n ≤ ψ Ｓｉ≤33° + 90° × n or 57° + 90° × n ≤ψ Ｓｉ The condition ≤ 71° + 90° × n is satisfied. As a result, unwanted bulk waves originating from the acoustic multilayer film 43 are more likely to leak to the support substrate 11, thereby suppressing the containment of unwanted waves in the piezoelectric layer 20 and improving the resonance characteristics.

[0071] In a desirable embodiment, the acoustic impedance of the first layer is higher than that of the second layer. This allows for good containment of the bulk wave of the thickness-slip first mode within the piezoelectric layer 20.

[0072] In a preferred embodiment, the first layer includes at least one of the following: tungsten carbide, tantalum carbide, rhenium oxide, silicon chromium, niobium carbide, zinc carbide, zinc nitride, lanthanum boride, vanadium carbide, aluminum nitride, silicon carbide, yttrium oxide, magnesium oxide, silicon nitride, boron carbide), strontium fluoride, barium fluoride, tantalum oxide, hafnium oxide, tungsten oxide, hafnium nitride, tungsten nitride, platinum, tungsten, copper, gold, and silver. This improves the acoustic impedance of the first layer.

[0073] In a more desirable embodiment, the first layer contains hafnium oxide. This allows for a further improvement in the acoustic impedance of the first layer.

[0074] In a preferred embodiment, the second layer contains at least one of silicon dioxide and aluminum. This reduces the acoustic impedance of the first layer.

[0075] In the elastic wave apparatus according to the first embodiment, an intermediate layer may be further provided between the support substrate 11 and the acoustic multilayer film 43. In this case as well, unwanted bulk waves originating from the acoustic multilayer film 43 can be suppressed, and the resonance characteristics can be improved.

[0076] In the elastic wave apparatus according to the first embodiment, the support substrate 11 may have a different acoustic impedance from at least one of the first layer and the second layer. Even in this case, unwanted bulk waves originating from the acoustic multilayer film 43 can be suppressed, and the resonance characteristics can be improved.

[0077] In a desirable configuration, the d / p ratio is 0.24 or less. This allows for even better resonance characteristics to be obtained.

[0078] In a desirable embodiment, when viewed from a direction perpendicular to the extending direction of the first electrode finger 31 and the second electrode finger 32, the region where adjacent first electrode finger 31 and second electrode finger 32 overlap, and the region between the centers of adjacent first electrode finger 31 and second electrode finger 32 in a direction perpendicular to the extending direction of the first electrode finger 31 and second electrode finger 32, is defined as the excitation region, and when the metallization ratio of the first electrode finger 31 and the second electrode finger 32 with respect to the excitation region is denoted as MR, the condition MR ≤ 1.75 (d / p) + 0.075 is satisfied. This effectively reduces spurious emissions and improves resonance characteristics.

[0079] In a desirable embodiment, the Euler angle (φ) of the lithium niobate constituting the piezoelectric layer 20 is Ｓｉ , θ Ｓｉ ψ Ｓｉ ) is within the range of equation (1), equation (2), or equation (3) below. This allows the relative bandwidth to be sufficiently wide. (0°±10°, 0°~20°, any ψ Ｓｉ )...Equation (1) (0°±10°, 20°~80°, 0°~60°(1-(θ Ｓｉ -50) ２ / 900) １／２ ) or (0°±10°, 20°~80°, [180°-60°(1-(θ) Ｓｉ -50) ２ / 900) １／２ ]~180°) ...Equation (2) (0°±10°, [180°−30°(1−(ψ Ｓｉ -90) ２ ( / 8100) １／２ ] ~180°, any ψ Ｓｉ ) ...Formula (3)

[0080] The following describes embodiments according to the first embodiment. However, the embodiments are not limited to those described in this example.

[0081] As an embodiment of the first embodiment, the elastic wave apparatus with the following design was simulated to determine the third component ψ of the resonance characteristics. ＳｉThe dependence was investigated. Here, the acoustic multilayer film was defined as a laminate containing a 3-layer first layer and a 4-layer second layer, with the first and second layers stacked alternately. The results are shown in Figure 16. Piezoelectric layer 20: Single crystal LiNbO ３ Layer (thickness 245 nm, Euler angles (0°, 120°, 0°)) IDT electrode 30: Laminate of Ti layer (thickness 12 nm) and AlCu layer (thickness 97 nm) Electrode pitch: 2.80 μm Electrode width: 0.48 μm Dielectric layer 41: SiO ２ Layer (thickness 95 nm) First layer of acoustic multilayer film: HfO ２ Layer (thickness 110 nm) Second layer of acoustic multilayer film: Low-density SiO ２ Layer (thickness 107 nm) Intermediate layer 12: SiO ２ Layer (thickness 700 nm) Support substrate 11: Single crystal silicon layer (thickness 3 μm, crystal plane of main surface 11a: (100), Euler angle: (90°, 90°, ψ Ｓｉ ))

[0082] Figure 16 shows the third component of the phase of the impedance of the elastic wave apparatus according to the first embodiment ψ Ｓｉ This figure shows a graph illustrating the dependence. As shown in Figure 16, the third component ψ of the Euler angle of single-crystal silicon Ｓｉ The phase of the impedance changes. The closer the impedance phase is to 90°, the more spurious emissions are suppressed and the better the resonance characteristics. In particular, ψ ｓｉ In the range greater than the central value of the impedance phase distribution range that depends on (the value obtained by adding the maximum and minimum values ​​and dividing by 2), the effect of improving the resonance characteristics is significant. In the first embodiment, the third component ψ Ｓｉ 19°≦ψ Ｓｉ ≤33° or 57°≤ψ Ｓｉ By being within the range E1 that satisfies ≤71°, spurious emissions originating from the acoustic multilayer film 43 can be suppressed, and the resonance characteristics can be improved.

[0083] Furthermore, the resonance characteristics were investigated by simulation of the elastic wave apparatus of the above design as Example 1 and Comparative Example 1. Here, Example 1 is an embodiment according to the first embodiment. In Example 1, the third component ψ of the Euler angle of the single crystal silicon of the support substrate 11 ＳｉIt is 25°. On the other hand, in Comparative Example 1, the third component ψ Ｓｉ The design was the same as in Example 1, except that the angle was changed to 45°. The results are shown in Figure 17.

[0084] Figure 17 is a graph showing the resonance characteristics for Example 1 and Comparative Example 1. As shown in Figure 17, the third component of the Euler angle ψ of the single-crystal silicon of the support substrate 11 Ｓｉ 19°≦ψ Ｓｉ ≤33° or 57°≤ψ Ｓｉ In Example 1, which falls within the range E1 satisfying ≤71°, the third component ψ Ｓｉ Compared to Comparative Example 1, in which the range E1 is not included, unwanted waves R originating from bulk waves were suppressed. As a result, the third component ψ of the Euler angle of the single-crystal silicon of the support substrate 11 was suppressed. Ｓｉ 19°≦ψ Ｓｉ ≤33° or 57°≤ψ Ｓｉ By satisfying the condition ≤ 71°, spurious emissions originating from the acoustic multilayer film 43 can be suppressed, thus improving the resonance characteristics.

[0085] (Second Embodiment) The second embodiment differs from the first embodiment in that the crystal plane of the single-crystal silicon on the main surface 11Aa of the support substrate 11A on the piezoelectric layer 20 side is a {110} plane.

[0086] Figure 18 is a schematic diagram showing the (110) plane of single-crystal silicon. In the second embodiment, the plane orientation of the single-crystal silicon on the main surface 11Aa of the support substrate 11A is {110}. Here, since the crystal axes of single-crystal silicon are equivalent, as in the first embodiment, the plane orientation {110} of the single-crystal silicon is not limited to the (110) plane shown in Figure 18, but includes crystal planes that are crystallinely equivalent to the (110) plane, such as the (011) plane and the (101) plane.

[0087] Figure 19 is a plan view from the Z direction of the crystal axis of the main surface on the piezoelectric layer side of the support substrate according to the second embodiment. In Figure 19, the crystal axis of single-crystal silicon is shown when the main surface 11Aa of the support substrate 11A is the (110) plane of single-crystal silicon. As shown in Figure 19, in the second embodiment, the crystal axis of the main surface 11Aa of the support substrate 11A is rotationally symmetric twice in plane, and an equivalent crystal structure is obtained by rotating it 180° around the Z axis. Here, the rotational symmetry of the crystal axis of single-crystal silicon of the support substrate 11A according to the second embodiment, as viewed from the Z direction, is the same even when the main surface 11Aa of the support substrate 11A is a plane equivalent to the (110) plane of single-crystal silicon, for example, the (011) plane or the (101) plane.

[0088] In the second embodiment, the first component φ of the Euler angle of the support substrate 11A Ｓｉ and the second component θ Ｓｉ The plane orientation of the main surface 11Aa is appropriately selected such that it is a {110} plane, for example, φ Ｓｉ = 45° and θ Ｓｉ = 35.26°. In the second embodiment, the third component ψ of the Euler angle of the support substrate 11A Ｓｉ 0°≦ψ Ｓｉ ≤22°, 41°≤ψ Ｓｉ ≤85°, 95°≤ψ Ｓｉ ≤139° or 160° ≤ψ Ｓｉ The condition ≤180° is satisfied. By keeping it within this range, unwanted bulk waves originating from the acoustic multilayer film 43 are more likely to leak to the support substrate 11A side, thereby suppressing the containment of unwanted waves in the piezoelectric layer 20 and improving the resonance characteristics.

[0089] In the second embodiment, as described above, the crystal axis of the single-crystal silicon of the support substrate 11A is rotationally symmetric twice in the Z direction when viewed in plan, so the Euler angle (φ) of the single-crystal silicon of the support substrate 11A Ｓｉ , θ Ｓｉ ψ Ｓｉ ) and (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ The expression (+180° × n) is equivalent for any integer n (=0, ±1, ±2, ...). Therefore, in the second embodiment, the third component ψ of the Euler angle of the support substrate 11A ＳｉThis is 0° + 180° × n ≤ ψ Ｓｉ ≤22° + 180° × n, 41° + 180° × n ≤ψ Ｓｉ ≤ 85° + 180° × n, 95° + 180° × n ≤ ψ Ｓｉ ≤ 139° + 180° × n or 160° + 180° × n ≤ ψ Ｓｉ The value must be ≤ 180° + 180° × n.

[0090] As described above, the elastic wave apparatus according to the second embodiment comprises a support substrate 11A containing single-crystal silicon, an acoustic multilayer film 43 provided on the upper side of the support substrate 11A, a piezoelectric layer 20 provided on the upper side of the acoustic multilayer film 43, and an IDT electrode 30 provided on the upper side of the piezoelectric layer 20. The acoustic multilayer film 43 includes a first layer and a second layer made of a different material from the first layer. The IDT electrode 30 has a first busbar 33 facing each other, a second busbar 34, at least one first electrode finger 31 whose base end is connected to the first busbar 33, and at least one second electrode finger 32 whose base end is connected to the second busbar 34. When the thickness of the piezoelectric layer 20 is d and the distance between the centers of adjacent first electrode fingers 31 and second electrode fingers 32 is p, d / p is 0.5 or less. The plane orientation of the single-crystal silicon on the main surface 11Aa of the support substrate 11A on the piezoelectric layer 20 side is the {110} plane. The Euler angle of the support substrate 11A is (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ ), when n is any integer, ψ Ｓｉ This is 0° + 180° × n ≤ ψ Ｓｉ ≤22° + 180° × n, 41° + 180° × n ≤ψ Ｓｉ ≤ 85° + 180° × n, 95° + 180° × n ≤ ψ Ｓｉ ≤ 139° + 180° × n or 160° + 180° × n ≤ ψ Ｓｉ The condition ≤ 180° + 180° × n is satisfied. As a result, unwanted bulk waves originating from the acoustic multilayer film 43 are more likely to leak to the support substrate 11A side, thereby suppressing the containment of unwanted waves in the piezoelectric layer 20 and improving the resonance characteristics.

[0091] The following describes an embodiment according to the second embodiment. However, this embodiment does not limit the possible embodiments.

[0092] As an embodiment of the second embodiment, the plane orientation of the single-crystal silicon on the main surface 11Aa of the support substrate 11A is set to the (110) plane, and the Euler angle of the single-crystal silicon is set to (180°, 180°, ψ Ｓｉ Except for the above, the elastic wave apparatus was designed to be the same as the elastic wave apparatus shown in Figure 20, and the third component of the resonance characteristic ψ was determined by simulation. Ｓｉ The dependency was investigated. The results are shown in Figure 20.

[0093] Figure 20 shows the third component of the phase of the impedance of the elastic wave apparatus according to the second embodiment ψ Ｓｉ This figure shows a graph illustrating the dependence. As shown in Figure 20, the third component ψ of the Euler angle of single-crystal silicon Ｓｉ The phase of the impedance changes. The closer the impedance phase is to 90°, the more spurious emissions are suppressed and the better the resonance characteristics. In particular, ψ ｓｉ In the range greater than the central value of the impedance phase distribution range that depends on (the value obtained by adding the maximum and minimum values ​​and dividing by 2), the effect of improving the resonance characteristics is greater. In the second embodiment, the third component ψ Ｓｉ 19°≦ψ Ｓｉ ≤33° or 57°≤ψ Ｓｉ By being within the range E2 that satisfies ≤71°, spurious emissions originating from the acoustic multilayer film 43 can be suppressed, and the resonance characteristics can be improved.

[0094] Furthermore, the resonance characteristics were investigated by simulation of the elastic wave apparatus of the above design as Example 2 and Comparative Example 2. Here, Example 2 is an embodiment according to the second embodiment. In Example 2, the third component ψ of the Euler angle of the single crystal silicon of the support substrate 11 Ｓｉ It is 62°. On the other hand, in Comparative Example 2, the third component ψ Ｓｉ The design was the same as in Example 2, except that the angle was changed to 30°. The results are shown in Figure 21.

[0095] Figure 21 is a graph showing the resonance characteristics for Example 2 and Comparative Example 2. As shown in Figure 21, the third component of the Euler angle ψ of the single-crystal silicon of the support substrate 11A Ｓｉ 0°≦ψ Ｓｉ ≤22°, 41°≤ψ Ｓｉ ≤85°, 95°≤ψ Ｓｉ≤139° or 160° ≤ψ Ｓｉ In Example 2, which falls within the range E2 satisfying ≤180°, the third component ψ Ｓｉ Compared to Comparative Example 2, in which the range E2 is not included, unwanted waves R originating from the bulk wave were suppressed. As a result, the third component ψ of the Euler angle of the single-crystal silicon of the support substrate 11A was suppressed. Ｓｉ 0°≦ψ Ｓｉ ≤22°, 41°≤ψ Ｓｉ ≤85°, 95°≤ψ Ｓｉ ≤139° or 160° ≤ψ Ｓｉ By satisfying the condition ≤180°, spurious emissions originating from the acoustic multilayer film 43 can be suppressed, thus improving the resonance characteristics.

[0096] (Third Embodiment) The third embodiment differs from the first embodiment in that the crystal plane of the single-crystal silicon on the main surface 11Ba of the support substrate 11B is a {111} plane.

[0097] Figure 22 is a schematic diagram showing the (111) plane of single-crystal silicon. In the third embodiment, the plane orientation of the single-crystal silicon on the main surface 11Ba of the support substrate 11B is {111}. Here, since the crystal axes of single-crystal silicon are equivalent, as in the first embodiment, the plane orientation {111} of the single-crystal silicon is not limited to the (111) plane shown in Figure 22, but includes crystallinely equivalent crystal planes.

[0098] Figure 23 is a plan view from the Z direction of the crystal axis of the main surface on the piezoelectric layer side of the support substrate according to the third embodiment. In Figure 23, the crystal axis of single-crystal silicon is shown when the main surface 11Ba of the support substrate 11B is the (111) plane of single-crystal silicon. As shown in Figure 23, in the third embodiment, the crystal axis of the main surface 11Ba of the support substrate 11B is rotationally symmetric three times in plane, and an equivalent crystal structure is obtained by rotating it 120° around the Z axis. Here, the rotational symmetry of the crystal axis of single-crystal silicon of the support substrate 11B according to the third embodiment, as viewed from the Z direction, is the same even when the main surface 11Ba of the support substrate 11B is a plane equivalent to the (111) plane of single-crystal silicon.

[0099] In the third embodiment, the first component φ of the Euler angle of the support substrate 11B Ｓｉ and the second component θ ＳｉThe plane orientation of the main surface 11Ba is appropriately selected such that it is a {111} plane, for example, φ Ｓｉ == -45° and θ Ｓｉ = -54.74. In the third embodiment, the third component ψ of the Euler angle of the support substrate 11B Ｓｉ 17°≦ψ Ｓｉ ≤43° or 78° ≤ψ Ｓｉ The condition ≤ 103° is satisfied. By keeping it within this range, unwanted bulk waves originating from the acoustic multilayer film 43 are more likely to leak to the support substrate 11B side, thereby suppressing the containment of unwanted waves in the piezoelectric layer 20 and improving the resonance characteristics.

[0100] In the third embodiment, as described above, the crystal axis of the single-crystal silicon of the support substrate 11B is rotationally symmetric three times in the Z direction when viewed in plan, so the Euler angle (φ) of the single-crystal silicon of the support substrate 11B Ｓｉ , θ Ｓｉ ψ Ｓｉ ) and (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ The expression (+120° × n) is equivalent for any integer n (=0, ±1, ±2, ...). Therefore, in the third embodiment, the third component ψ of the Euler angle of the support substrate 11B Ｓｉ This is 17° + 120° × n ≤ ψ Ｓｉ ≤43° + 120° × n or 78° + 120° × n ≤ψ Ｓｉ The value must be ≤ 103° + 120° × n.

[0101] As described above, the elastic wave apparatus according to the third embodiment comprises a support substrate 11B containing single-crystal silicon, an acoustic multilayer film 43 provided on the upper side of the support substrate 11B, a piezoelectric layer 20 provided on the upper side of the acoustic multilayer film 43, and an IDT electrode 30 provided on the upper side of the piezoelectric layer 20. The acoustic multilayer film 43 includes a first layer and a second layer made of a different material from the first layer. The IDT electrode 30 has a first busbar 33 facing each other, a second busbar 34, at least one first electrode finger 31 whose base end is connected to the first busbar 33, and at least one second electrode finger 32 whose base end is connected to the second busbar 34. When the thickness of the piezoelectric layer 20 is d and the distance between the centers of adjacent first electrode fingers 31 and second electrode fingers 32 is p, d / p is 0.5 or less. The plane orientation of the single-crystal silicon on the main surface 11Ba of the support substrate 11B on the piezoelectric layer 20 side is the {111} plane. The Euler angle of the support substrate 11B is (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ ), when n is any integer, the above ψ Ｓｉ This is 17° + 120° × n ≤ ψ Ｓｉ ≤43° + 120° × n or 78° + 120° × n ≤ψ Ｓｉ The condition ≤ 103° + 120° × n is satisfied. As a result, unwanted bulk waves originating from the acoustic multilayer film 43 are more likely to leak to the support substrate 11B side, thereby suppressing the containment of unwanted waves in the piezoelectric layer 20 and improving the resonance characteristics.

[0102] The following describes an embodiment according to the third embodiment. However, this embodiment does not limit the possible embodiments.

[0103] As an embodiment of the third embodiment, the plane orientation of the single-crystal silicon on the main surface 11Ba of the support substrate 11B is set to the (111) plane, and the Euler angle of the single-crystal silicon is set to (120°, 120°, ψ Ｓｉ Except for the above, the elastic wave apparatus was designed to be the same as the elastic wave apparatus shown in Figure 24, and the third component of the resonance characteristic ψ was determined by simulation. Ｓｉ The dependency was investigated. The results are shown in Figure 24.

[0104] Figure 24 shows the third component of the phase of the impedance of the elastic wave apparatus according to the third embodiment ψ ＳｉThis figure shows a graph illustrating the dependence. As shown in Figure 24, the third component ψ of the Euler angle of single-crystal silicon Ｓｉ The phase of the impedance changes. The closer the impedance phase is to 90°, the more spurious emissions are suppressed and the better the resonance characteristics. In particular, ψ ｓｉ In the range greater than the central value of the impedance phase distribution range that depends on (the value obtained by adding the maximum and minimum values ​​and dividing by 2), the effect of improving the resonance characteristics is greater. In the third embodiment, the third component ψ Ｓｉ 17°≦ψ Ｓｉ ≤43° or 78° ≤ψ Ｓｉ By being within the range E3 that satisfies ≤103°, spurious emissions originating from the acoustic multilayer film 43 can be suppressed, and the resonance characteristics can be improved.

[0105] Furthermore, the resonance characteristics were investigated by simulation of the elastic wave apparatus of the above design as Example 3 and Comparative Example 3. Here, Example 3 is an embodiment according to the third embodiment. In Example 3, the third component ψ of the Euler angle of the single crystal silicon of the support substrate 11B Ｓｉ It is 26°. On the other hand, in Comparative Example 3, the third component ψ Ｓｉ The design was the same as in Example 3, except that the angle was changed to 0°. The results are shown in Figure 25.

[0106] Figure 25 is a graph showing the resonance characteristics for Example 3 and Comparative Example 3. As shown in Figure 25, the third component of the Euler angle ψ of the single-crystal silicon of the support substrate 11B Ｓｉ 17°≦ψ Ｓｉ ≤43° or 78° ≤ψ Ｓｉ In Example 3, which falls within the range E3 satisfying ≤103°, the third component ψ Ｓｉ Compared to Comparative Example 3, in which the range E3 is not included, unwanted waves R originating from the bulk wave were suppressed. As a result, the third component ψ of the Euler angle of the single-crystal silicon of the support substrate 11B was suppressed. Ｓｉ 17°≦ψ Ｓｉ ≤43° or 78° ≤ψ Ｓｉ By satisfying the condition ≤ 103°, spurious emissions originating from the acoustic multilayer film 43 can be suppressed, thus improving the resonance characteristics.

[0107] (Fourth Embodiment) Figure 26 is a circuit diagram showing a filter according to the fourth embodiment. As shown in Figure 26, the filter 50 according to the fourth embodiment is a so-called ladder type filter.

[0108] In the fourth embodiment, the filter 50 is a so-called bandpass filter that allows waves of a specific frequency band to pass through. The filter 50 includes a plurality of series arm resonators S1, S2, S3, S4 and a plurality of parallel arm resonators P1, P2, P3. The plurality of series arm resonators S1, S2, S3, S4 are connected in series to the signal path (series arm) between the input terminal 56 and the output terminal 55. The plurality of parallel arm resonators P1, P2, P3 are connected in parallel to the signal path (parallel arm) connecting the nodes on the series arm to ground.

[0109] One terminal of each of the series-connected series arm resonators S1, S2, S3, and S4 is electrically connected to the input terminal 56, and the other terminal is electrically connected to the output terminal 55. One terminal of the parallel arm resonator P1 is electrically connected to a node between the series arm resonators S1 and S2, and the other terminal is electrically connected to ground. One terminal of the parallel arm resonator P2 is electrically connected to a node between the series arm resonators S2 and S3, and the other terminal is electrically connected to ground. One terminal of the parallel arm resonator P3 is electrically connected to a node between the series arm resonators S3 and S4, and the other terminal is electrically connected to ground.

[0110] In the fourth embodiment, at least one of the resonators included in the filter 50 (series arm resonators S1, S2, S3, S4 and parallel arm resonators P1, P2, P3) is an elastic wave device 10 according to any of the first to third embodiments. Since the filter 50 according to the fourth embodiment has an elastic wave device 10 according to any of the first to third embodiments, spurious emissions due to bulk waves originating from the acoustic multilayer film 43 can be suppressed, thereby improving the filter characteristics. Furthermore, when the filter 50 and other filters are commonly connected to the input terminal, the influence of spurious emissions due to bulk waves originating from the acoustic multilayer film 43 on the other filters can be suppressed, thereby improving the filter characteristics.

[0111] In the fourth embodiment, it is preferable that at least one of the series arm resonators S1, S2, S3, and S4 is an elastic wave device 10 according to any of the first to third embodiments, and it is more preferable that all of the series arm resonators S1, S2, S3, and S4 are elastic wave devices 10 according to any of the first to third embodiments. Since the series arm resonators are resonators that affect the filter characteristics near the resonance frequency of the filter 50, by using the elastic wave device 10 of this disclosure as a series arm resonator, spurious signals of bulk waves originating from the acoustic multilayer film 43 that appear near the resonance frequency can be suppressed, and the filter characteristics can be improved.

[0112] As described above, the filter 50 according to the fourth embodiment is a filter equipped with resonators (series arm resonators S1, S2, S3, S4 and parallel arm resonators P1, P2, P3). At least one of the resonators is an elastic wave device 10 according to any one of the first to third embodiments. This makes it possible to suppress spurious emissions caused by bulk waves originating from the acoustic multilayer film 43, thereby improving the filter characteristics.

[0113] In a preferred embodiment, the filter 50 according to the fourth embodiment comprises a plurality of resonators (series arm resonators S1, S2, S3, S4 and parallel arm resonators P1, P2, P3), an input terminal 56, an output terminal 55, a series arm connecting the input terminal 56 and the output terminal 55, and a parallel arm connecting the node of the series arm to ground. The plurality of resonators include series arm resonators S1, S2, S3, S4 provided on the series arm and parallel arm resonators P1, P2, P3 provided on the parallel arm. At least one of the series arm resonators S1, S2, S3, S4 is an elastic wave device according to any one of the first to third embodiments. This suppresses spurious signals of bulk waves originating from the acoustic multilayer film 43 that appear near the resonant frequency, thereby further improving the filter characteristics.

[0114] (Fifth Embodiment) Figure 27 is a schematic circuit diagram of a duplexer according to the fifth embodiment. In Figure 27, the filter 61B is schematically shown by a block diagram.

[0115] The duplexer 60 has an input terminal 56 and filters 61A and 61B that are commonly connected to the input terminal 56. Here, the input terminal 56 is an example of a signal terminal in this disclosure. The passbands of filters 61A and 61B are different. In the example of Figure 27, filter 61A is filter 50 according to the fourth embodiment. The circuit configuration of filter 61B is not particularly limited and may be, for example, a ladder type filter such as filter 50 according to the fourth embodiment, or a longitudinally coupled resonator type elastic wave filter. Note that filter 61A is not limited to filter 50 according to the fourth embodiment. The filter 61A of the duplexer according to the fifth embodiment may include at least one elastic wave device 10 according to any of the first to third embodiments.

[0116] The filter 61A of the duplexer 60 according to the fifth embodiment has at least one elastic wave device according to any of the first to third embodiments, so that spurious emissions due to bulk waves originating from the acoustic multilayer film 43 can be suppressed, thereby improving the filter characteristics. Furthermore, the influence of spurious emissions due to bulk waves originating from the acoustic multilayer film 43 on the filter 61B, which is commonly connected to the input terminal 56 of the filter 61A, can be suppressed, thereby improving the filter characteristics.

[0117] As described above, the duplexer 60 according to the fifth embodiment has a signal terminal (input terminal 56) and two filters 61A and 61B connected to the signal terminal, and at least one of the two filters 61A and 61B (filter 61A) is the filter 50 according to the fourth embodiment. This makes it possible to suppress spurious signals caused by bulk waves originating from the acoustic multilayer film 43, thereby improving the filter characteristics.

[0118] (Sixth Embodiment) Figure 28 is a schematic diagram of a multiplexer according to the sixth embodiment. In Figure 28, filters 61A, 71B, and 71C, which will be described later, are schematically shown in block diagrams.

[0119] The multiplexer 70 has an input terminal 56 and filters 61A, 71B, and 71C that are commonly connected to the input terminal 56. Here, the input terminal 56 is an example of a signal terminal in this disclosure. Filter 61A is filter 50 according to the fourth embodiment. The circuit configuration of filters 71B and 71C is not particularly limited and may be, for example, filter 50 according to the fourth embodiment. The multiplexer 70 may also include filter devices other than filters 61A, 71B, and 71C that are connected to the input terminal 56. As with the fifth embodiment, filter 61A is not limited to filter 50 according to the fourth embodiment and may include at least one elastic wave device 10 according to any of the first to third embodiments.

[0120] The filter 61A of the multiplexer 70 according to the sixth embodiment has at least one elastic wave device according to any of the first to third embodiments, so that spurious emissions due to bulk waves originating from the acoustic multilayer film 43 can be suppressed, thereby improving the filter characteristics. Furthermore, the influence of spurious emissions due to bulk waves originating from the acoustic multilayer film 43 can be suppressed on filters 71B and 71C which are commonly connected to the input terminal 56 with filter 61A, thereby improving the filter characteristics.

[0121] As described above, the multiplexer 70 according to the sixth embodiment has a signal terminal (input terminal 56) and a plurality of filters 61A, 71B, and 71C connected to the signal terminal, and at least one of the plurality of filters 61A, 71B, and 71C (filter 61A) is the filter 50 according to the fourth embodiment. This makes it possible to suppress spurious signals caused by bulk waves originating from the acoustic multilayer film 43, thereby improving the filter characteristics.

[0122] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention may be modified or improved without departing from its spirit, and equivalents thereof are also included.

[0123] 10 Elastic wave device 11, 11A, 11B Support substrate 11a, 11Aa, 11Ba Main surface 12 Intermediate layer 20 Piezoelectric layer 20a First main surface 20b Second main surface 30 IDT electrode 31 First electrode finger 32 Second electrode finger 33 First busbar 34 Second busbar 41 Dielectric layer 43 Acoustic multilayer film 50 Filter 55 Output terminal 56 Input terminal 60 Duplexer 61A, 61B Filter 70 Multiplexer 71B, 71C Filter

Claims

1. The device comprises: a support substrate containing single-crystal silicon; an acoustic multilayer film provided on the upper side of the support substrate; a piezoelectric layer provided on the upper side of the acoustic multilayer film; and an IDT electrode provided on the upper side of the piezoelectric layer, wherein the acoustic multilayer film includes a first layer and a second layer made of a different material from the first layer; the IDT electrode has a first busbar facing each other, a second busbar, at least one first electrode finger whose base end is connected to the first busbar, and at least one second electrode finger whose base end is connected to the second busbar; when the thickness of the piezoelectric layer is d and the distance between the centers of adjacent first and second electrode fingers is p, d / p is 0.5 or less; the plane orientation of the single-crystal silicon on the main surface of the support substrate on the piezoelectric layer side is the {100} plane; and the Euler angle of the support substrate is (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ ), when n is any integer, the above ψ Ｓｉ This is 19° + 90° × n ≤ ψ Ｓｉ ≤33° + 90° × n or 57° + 90° × n ≤ψ Ｓｉ An elastic wave device that satisfies ≤ 71° + 90° × n.

2. A support substrate including single crystal silicon, an acoustic multilayer film provided on the upper side of the support substrate, a piezoelectric layer provided on the upper side of the acoustic multilayer film, and an IDT electrode provided on the upper side of the piezoelectric layer, wherein the acoustic multilayer film includes a first layer and a second layer made of a material different from the first layer, the IDT electrode has a first bus bar and a second bus bar facing each other, at least one first electrode finger having a base end connected to the first bus bar, and at least one second electrode finger having a base end connected to the second bus bar, when the film thickness of the piezoelectric layer is d and the center-to-center distance between adjacent first and second electrode fingers is p, d / p is 0.5 or less, the plane orientation of the single crystal silicon on the main surface of the support substrate on the piezoelectric layer side is the {110} plane, and the Euler angles of the support substrate are (φ Ｓｉ , θ Ｓｉ , ψ Ｓｉ ), when n is an arbitrary integer, ψ Ｓｉ satisfies 0° + 180°×n ≤ ψ Ｓｉ ≤ 22° + 180°×n, 41° + 180°×n ≤ ψ Ｓｉ ≤ 85° + 180°×n, 95° + 180°×n ≤ ψ Ｓｉ ≤ 139° + 180°×n or 160° + 180°×n ≤ ψ Ｓｉ ≤ 180° + 180°×n, a surface acoustic wave device.

3. The device comprises: a support substrate containing single-crystal silicon; an acoustic multilayer film provided on the upper side of the support substrate; a piezoelectric layer provided on the upper side of the acoustic multilayer film; and an IDT electrode provided on the upper side of the piezoelectric layer, wherein the acoustic multilayer film includes a first layer and a second layer made of a different material from the first layer; the IDT electrode has a first busbar facing each other, a second busbar, at least one first electrode finger whose base end is connected to the first busbar, and at least one second electrode finger whose base end is connected to the second busbar; when the thickness of the piezoelectric layer is d and the distance between the centers of adjacent first and second electrode fingers is p, d / p is 0.5 or less; the plane orientation of the single-crystal silicon on the main surface of the support substrate on the piezoelectric layer side is the {111} plane; and the Euler angle of the support substrate is (φ Ｓｉ , θ Ｓｉ ψ Ｓｉ ), when n is any integer, the above ψ Ｓｉ This is 17° + 120° × n ≤ ψ Ｓｉ ≤43° + 120° × n or 78° + 120° × n ≤ψ Ｓｉ An elastic wave device that satisfies ≤ 103° + 120° × n.

4. The elastic wave apparatus according to any one of claims 1 to 3, wherein the acoustic impedance of the first layer is higher than the acoustic impedance of the second layer.

5. The elastic wave apparatus according to any one of claims 1 to 4, wherein the first layer comprises at least one of tungsten carbide, tantalum carbide, rhenium oxide, silicon chromium, niobium carbide, zinc carbide, zinc nitride, lanthanum boride, vanadium carbide, aluminum nitride, silicon carbide, yttrium oxide, magnesium oxide, silicon nitride, boron carbide), strontium fluoride, barium fluoride, tantalum oxide, hafnium oxide, tungsten oxide, hafnium nitride, tungsten nitride, platinum, tungsten, copper, gold, and silver.

6. The elastic wave apparatus according to claim 5, wherein the first layer comprises hafnium oxide.

7. The acoustic wave apparatus according to any one of claims 1 to 6, wherein the second layer comprises at least one of silicon oxide and aluminum.

8. The elastic wave apparatus according to any one of claims 1 to 7, further comprising an intermediate layer provided between the support substrate and the acoustic multilayer film.

9. The elastic wave apparatus according to any one of claims 1 to 8, wherein the support substrate has an acoustic impedance different from that of at least one of the first layer and the second layer.

10. The elastic wave apparatus according to any one of claims 1 to 9, wherein the d / p is 0.24 or less.

11. The elastic wave apparatus according to any one of claims 1 to 10, wherein, when viewed from a direction perpendicular to the extending direction of the first electrode finger and the second electrode finger, the region in which adjacent first electrode finger and second electrode finger overlap, and the region between the centers of adjacent first electrode finger and second electrode finger in a direction perpendicular to the extending direction of the first electrode finger and second electrode finger is defined as the excitation region, and when the metallization ratio of the first electrode finger and second electrode finger with respect to the excitation region is denoted as MR, the condition MR ≤ 1.75 (d / p) + 0.075 is satisfied.

12. The Euler angle (φ) of the lithium niobate constituting the piezoelectric layer. ＬＮ , θ ＬＮ ψ ＬＮ The elastic wave apparatus according to any one of claims 1 to 11, wherein the ψ is within the range of the following equations (1), (2), or (3): (0°±10°, 0° to 20°, any ψ ＬＮ )...Equation (1) (0°±10°, 20°~80°, 0°~60°(1-(θ ＬＮ -50) ２ / 900) １／２ ) or (0°±10°, 20°~80°, [180°-60°(1-(θ) ＬＮ -50) ２ / 900) １／２ ]~180°) ...Formula (2) (0°±10°, [180°−30°(1−(ψ ＬＮ -90) ２ ( / 8100) １／２ ] ~180°, any ψ ＬＮ )...Formula (3) 13. A filter comprising a resonator, wherein at least one of the resonators is an elastic wave apparatus according to any one of claims 1 to 12.

14. The filter according to claim 13, comprising a plurality of resonators, having an input terminal, an output terminal, a series arm connecting the input terminal and the output terminal, and a parallel arm connecting the node of the series arm to ground, wherein the plurality of resonators include a series arm resonator provided on the series arm and a parallel arm resonator provided on the parallel arm, and at least one of the series arm resonators is the elastic wave device.

15. A duplexer having a signal terminal and two filters connected to the signal terminal, wherein at least one of the two filters is the filter described in claim 13.

16. A multiplexer having a signal terminal and a plurality of filters connected to the signal terminal, wherein at least one of the plurality of filters is the filter described in claim 13.

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