Elastic wave device and communication device

Abstract

An elastic wave device is reduced in size. This elastic wave device is provided with: a support substrate; a piezoelectric layer in direct or indirect contact with the support substrate; and an IDT electrode on the piezoelectric body layer; the elastic wave device excites the asymmetric zero-order mode Lamb wave.

Description

Technical Field

[0001] The present disclosure relates to an elastic wave device and a communication device. Background Art

[0002] Conventionally, an elastic wave element having the following structure is known: an IDT (Interdigital Transducer) is formed on a piezoelectric crystal. The elastic wave element can be used as a filter (SAW filter) that, for example, excites an elastic surface acoustic wave (SAW: Surface Acoustic Wave) near a specific frequency and receives an electrical signal near a specific frequency. The elastic wave element is used for a bandpass filter in a communication device, etc. (for example, see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-257019 Summary of the invention

[0006] An elastic wave device according to one aspect of the present disclosure includes: a supporting substrate; a piezoelectric layer directly or indirectly connected to the supporting substrate; and an IDT electrode located on the piezoelectric layer; and the elastic wave device excites an asymmetric 0th-order Lamb wave. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a perspective view showing a configuration example of an elastic wave device in one embodiment of the present disclosure.

[0008] Figure 2 It is a cross-sectional view showing a configuration example of an elastic wave device in one embodiment of the present disclosure.

[0009] Figure 3 This is a diagram showing an overview of a FEM simulation model of an elastic wave device.

[0010] Figure 4 It is a table showing FEM simulation conditions.

[0011] Figure 5A This is a table showing FEM simulation conditions related to the Al electrode thickness in Study Example 1.

[0012] Figure 5B This is a diagram showing the results of FEM simulation of the relationship between the Al electrode thickness and the specific bandwidth Δf in Investigation Example 1.

[0013] Figure 5C This is a diagram showing the results of FEM simulation of the relationship between the Al electrode thickness and the sound velocity V in Investigation Example 1.

[0014] Fig. 6A This is a table showing FEM simulation conditions related to LT thickness in Study Example 1.

[0015] Figure 6B This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the specific bandwidth Δf in Investigation Example 1.

[0016] Figure 6C This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the sound velocity V in Investigation Example 1.

[0017] Fig. 7A This is a table showing FEM simulation conditions related to the LT cut angle in Study Example 1.

[0018] Figure 7B This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the specific bandwidth Δf in Investigation Example 1.

[0019] Figure 7C This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the sound velocity V in Investigation Example 1.

[0020] Fig. 8A This is a table showing FEM simulation conditions related to the LT propagation angle in Study Example 1.

[0021] Figure 8B This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the specific bandwidth Δf in Investigation Example 1.

[0022] Figure 8C This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the sound velocity V in Investigation Example 1.

[0023] Fig.9A This is a table showing FEM simulation conditions related to the Cu electrode thickness in Investigation Example 2.

[0024] Fig. 9B This is a diagram showing the results of FEM simulation of the relationship between the Cu electrode thickness and the specific bandwidth Δf in Investigation Example 2.

[0025] Fig. 9C This is a diagram showing the results of FEM simulation of the relationship between the Cu electrode thickness and the sound velocity V in Investigation Example 2.

[0026] Fig. 10A This is a table showing FEM simulation conditions related to LT thickness in Investigation Example 2.

[0027] Fig. 10B This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the specific bandwidth Δf in Investigation Example 2.

[0028] Fig. 10C This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the sound velocity V in Investigation Example 2.

[0029] Fig.11A This is a table showing FEM simulation conditions related to the LT cut angle in Study Example 2.

[0030] Fig. 11B This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the specific bandwidth Δf in Investigation Example 2.

[0031] Fig. 11C This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the sound velocity V in Investigation Example 2.

[0032] Fig. 12A This is a table showing FEM simulation conditions related to the LT propagation angle in Investigation Example 2.

[0033] Fig. 12B This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the specific bandwidth Δf in Investigation Example 2.

[0034] Fig. 12C This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the sound velocity V in Investigation Example 2.

[0035] Fig.13A This is a table showing FEM simulation conditions related to the Pt electrode thickness in Investigation Example 3.

[0036] Fig. 13B This is a diagram showing the results of FEM simulation of the relationship between the Pt electrode thickness and the specific bandwidth Δf in Investigation Example 3.

[0037] Fig. 13C This is a diagram showing the results of FEM simulation of the relationship between the thickness of the Pt electrode and the acoustic velocity V in Investigation Example 3.

[0038] Fig.14A This is a table showing FEM simulation conditions related to LT thickness in Investigation Example 3.

[0039] Fig. 14B This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the specific bandwidth Δf in Investigation Example 3.

[0040] Fig. 14C This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the sound velocity V in Investigation Example 3.

[0041] Fig.15A This is a table showing FEM simulation conditions related to the LT cut angle in Investigation Example 3.

[0042] Fig. 15BThis is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the specific bandwidth Δf in Investigation Example 3.

[0043] Fig. 15C This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the sound velocity V in Investigation Example 3.

[0044] Fig.16A This is a table showing FEM simulation conditions related to the LT propagation angle in Investigation Example 3.

[0045] Fig. 16B This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the specific bandwidth Δf in Investigation Example 3.

[0046] Fig. 16C This is a diagram showing the results of FEM simulation for investigating the relationship between the LT propagation angle and the sound velocity V in Example 3.

[0047] Fig.17A This is a table showing the shear wave sound speed of major metal materials.

[0048] Fig. 17B This is a diagram showing a calculation formula for the shear wave sound velocity.

[0049] Fig.18A This is a diagram showing the relationship between the transverse wave sound velocity of the electrode material and the center point CP of the electrode thickness in the results of the investigation of Examples 1 to 3.

[0050] Fig.18B This is a graph showing the relationship between the transverse wave velocity and the sound velocity (elastic wave velocity) V of the electrode material in the results of the investigation of Examples 1 to 3.

[0051] Fig.18C This is a graph showing the relationship between the transverse wave sound velocity and the specific bandwidth Δf of the electrode material in the results of the investigation of Examples 1 to 3.

[0052] Fig.19A This is a table showing FEM simulation conditions related to the Al electrode thickness in Investigation Example 5.

[0053] Fig.19B This is a diagram showing the results of FEM simulation of the relationship between the Al electrode thickness and the specific bandwidth Δf in Investigation Example 5.

[0054] Fig.19C This is a diagram showing the results of FEM simulation of the relationship between the Al electrode thickness and the sound velocity V in Investigation Example 5.

[0055] Fig. 20A This is a table showing FEM simulation conditions related to LN thickness in Investigation Example 5.

[0056] Fig. 20BThis is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the specific bandwidth Δf in Investigation Example 5.

[0057] Fig. 20C This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the sound velocity V in Investigation Example 5.

[0058] Fig.21A This is a table showing FEM simulation conditions related to the LN cut angle in Investigation Example 5.

[0059] Fig.21B This is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the specific bandwidth Δf in Investigation Example 5.

[0060] Fig. 21C This is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the sound velocity V in Investigation Example 5.

[0061] Fig.22A This is a table showing FEM simulation conditions related to the LN propagation angle in Study Example 5.

[0062] Fig. 22B 1 is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the specific bandwidth Δf in Investigation Example 5.

[0063] Fig. 22C This is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the sound velocity V in Investigation Example 5.

[0064] Fig.23A This is a table showing FEM simulation conditions related to the Cu electrode thickness in Investigation Example 6.

[0065] Fig. 23B This is a diagram showing the results of FEM simulation of the relationship between the Cu electrode thickness and the specific bandwidth Δf in Investigation Example 6.

[0066] Fig.23C This is a diagram showing the results of FEM simulation of the relationship between the Cu electrode thickness and the sound velocity V in Investigation Example 6.

[0067] Fig.24A This is a table showing FEM simulation conditions related to LN thickness in Investigation Example 6.

[0068] Fig. 24B This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the specific bandwidth Δf in Investigation Example 6.

[0069] Fig.24C This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the sound velocity V in Investigation Example 6.

[0070] Fig.25AThis is a table showing FEM simulation conditions related to the LN cut angle in Investigation Example 6.

[0071] Fig.25B 1 is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the specific bandwidth Δf in Investigation Example 6.

[0072] Fig.25C This is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the sound velocity V in Investigation Example 6.

[0073] Fig.26A This is a table showing FEM simulation conditions related to the LN propagation angle in Study Example 6.

[0074] Fig.26B This is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the specific bandwidth Δf in Investigation Example 6.

[0075] Fig.26C This is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the sound velocity V in Investigation Example 6.

[0076] Fig.27A This is a table showing FEM simulation conditions related to the Pt electrode thickness in Investigation Example 7.

[0077] Fig.27B This is a diagram showing the results of FEM simulation of the relationship between the Pt electrode thickness and the specific bandwidth Δf in Investigation Example 7.

[0078] Fig.27C This is a diagram showing the results of FEM simulation of the relationship between the thickness of the Pt electrode and the acoustic velocity V in Investigation Example 7.

[0079] Fig.28A This is a table showing FEM simulation conditions related to LN thickness in Investigation Example 7.

[0080] Fig.28B This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the specific bandwidth Δf in Investigation Example 7.

[0081] Fig.28C This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the sound velocity V in Investigation Example 7.

[0082] Fig.29A This is a table showing FEM simulation conditions related to the LN cutting angle in Investigation Example 7.

[0083] Fig.29B 1 is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the specific bandwidth Δf in Investigation Example 7.

[0084] Fig.29CThis is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the sound velocity V in Investigation Example 7.

[0085] Fig. 30A This is a table showing FEM simulation conditions related to the LN propagation angle in Study Example 7.

[0086] Fig. 30B 1 is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the specific bandwidth Δf in Investigation Example 7.

[0087] Fig. 30C This is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the sound velocity V in Investigation Example 7.

[0088] Fig.31A This is a diagram showing the relationship between the transverse wave velocity of the electrode material and the center point CP of the electrode thickness in the results of studying Examples 5 to 7.

[0089] Fig.31B This is a graph showing the relationship between the transverse wave velocity and the sound velocity (elastic wave velocity) V of the electrode material in the results of studying Examples 5 to 7.

[0090] Fig. 31C This is a graph showing the relationship between the transverse wave sound velocity and the specific bandwidth Δf of the electrode material in the results of studying Examples 5 to 7.

[0091] Fig.32 It is a perspective view showing another configuration example of the elastic wave device in one embodiment of the present disclosure.

[0092] Fig.33 It is a cross-sectional view showing another configuration example of the elastic wave device in one embodiment of the present disclosure.

[0093] Fig.34 It is a cross-sectional view showing another configuration example of the elastic wave device in one embodiment of the present disclosure.

[0094] Fig.35 This is a diagram illustrating a schematic configuration of a communication device. DETAILED DESCRIPTION

[0095] Hereinafter, an elastic wave device as an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. However, the following description is for a better understanding of the main purpose of the invention, and does not limit the present disclosure unless otherwise specified. In this specification, "A to B" indicating a numerical range means "above A and below B" unless otherwise specified. In addition, for the sake of convenience, the figures referred to in the following description only show the main components required to illustrate the embodiment in a simplified manner, and well-known technical matters are appropriately omitted for the sake of simplicity. Therefore, the elastic wave device in the present embodiment may arbitrarily include well-known components not shown in the referenced figures. In addition, the dimensions of the components in the figures do not faithfully represent the dimensions of the actual components and the dimensional ratios of the components.

[0096] <Overview of the Configuration of the Elastic Wave Device>

[0097] Figure 1 It is a perspective view showing a configuration example of elastic wave device 100 according to the present embodiment. Figure 2 2 is a cross-sectional view showing an example of the configuration of elastic wave device 100 in this embodiment. The specific shape of IDT electrode 3 in elastic wave device 100 in this embodiment is not particularly limited, and electrode fingers 32 of IDT electrode 3 can be formed in various known shapes. Figure 1 In FIG. 1 , only the electrode fingers 32 of the IDT electrode 3 are shown with oblique line hatching. Figure 2 In the cross-sectional views referred to in the following description, for the sake of planarization of the drawings, drawings (cut-away cross-sectional views) in which members on the back side of the cross-sections are omitted are shown.

[0098] like Figure 1 as well as Figure 2 As shown, an elastic wave device 100 according to one aspect of the present disclosure may have at least one resonator 1. In one example of the elastic wave device 100, an input terminal Tin and an output terminal Tout may be connected to the resonator 1. The resonator 1 may be configured as a frequency filter (SAW filter) that filters an electrical signal input to the input terminal Tin and outputs the filtered electrical signal to the output terminal Tout.

[0099] The elastic wave device 100 may include: a support substrate 5; a piezoelectric layer 2 directly or indirectly connected to the support substrate 5; and an IDT electrode 3 located on the piezoelectric layer 2. The IDT electrode 3 is also called an excitation electrode. In addition, the elastic wave device 100 in this embodiment is configured to effectively excite an asymmetric 0th-order Lamb wave. This will be described in detail later.

[0100] When elastic wave device 100 includes a plurality of resonators 1 , the plurality of resonators 1 may share support substrate 5 and piezoelectric layer 2 . The plurality of resonators 1 may each have an independent IDT electrode 3 .

[0101] Support substrate 5 supports various parts of elastic wave device 100. The specific material of support substrate 5 is not particularly limited, and it may be, for example, a Si substrate.

[0102] The piezoelectric layer 2 may be made of a single crystal material having piezoelectricity. For example, the material of the piezoelectric layer 2 may be lithium tantalate (LiTaO3: also referred to as LT) or lithium niobate (LiNbO3: also referred to as LN).

[0103] The elastic wave device 100 may include an intermediate layer 6 located between the support substrate 5 and the piezoelectric layer 2. The support substrate 5 and the piezoelectric layer 2 may be bonded via the intermediate layer 6. The constituent material of the intermediate layer 6 may be typically silicon oxide (SiO x ). As an example, the intermediate layer 6 can be a SiO2 film. The elastic wave device 100 may not have the intermediate layer 6. The elastic wave device 100 having the intermediate layer 6 is easier to manufacture than the elastic wave device 100 not having the intermediate layer 6. In addition, when the elastic wave device 100 does not have the intermediate layer 6, during the manufacturing process of the elastic wave device 100, a bonding layer formed between the supporting substrate 5 and the piezoelectric layer 2 by bonding them may have an adverse effect on the filter characteristics of the elastic wave device 100. This is because the distance between the bonding layer and the surface of the piezoelectric layer 2 on the side away from the supporting substrate 5 becomes closer.

[0104] The IDT electrode 3 is typically an interdigitated electrode that is periodically configured with an electrode pair consisting of a positive first electrode finger 32a and a negative second electrode finger 32b. On the surface of the piezoelectric layer 2, the propagation direction of the SAW excited by the IDT electrode 3 is a direction orthogonal to the direction in which the first electrode finger 32a and the second electrode finger 32b extend.

[0105] exist Figure 1 In the embodiment, the propagation direction of the SAW propagating on the surface of the piezoelectric layer 2 in the elastic wave device 100 is set as the x direction, the thickness direction of each component of the elastic wave device 100 is set as the z direction, and the direction orthogonal to the x direction and the z direction is set as the y direction. In the following, the positive direction in the z direction is sometimes referred to as the upward direction, and the negative direction in the z direction is sometimes referred to as the downward direction. In addition, in the drawings referred to in the following description, the Figure 1 The orthogonal coordinate system (xyz coordinate system) shown.

[0106] The IDT electrode 3 may include: two bus bars 31 (a first bus bar 31a and a second bus bar 31b) facing each other in the y direction. The IDT electrode 3 may include: a plurality of first electrode fingers 32a connected to the first bus bar 31a; and a plurality of second electrode fingers 32b connected to the second bus bar 31b. The first electrode fingers 32a may extend from the first bus bar 31a to the second bus bar 31b in the y direction. The second electrode fingers 32b may extend from the second bus bar 31b to the first bus bar 31a in the y direction.

[0107] Reference Figure 2 , the first electrode finger 32a and the second electrode finger 32b can be alternately and repeatedly located on the piezoelectric layer 2 in a manner having a substantially constant interval in the x direction. In this specification, the first electrode finger 32a and the second electrode finger 32b are sometimes collectively referred to as electrode fingers 32. The electrode finger pitch (electrode finger pitch) p in the IDT electrode 3 can be the distance between the centers of two adjacent electrode fingers 32 in the x direction (in other words, the repetition interval of the electrode fingers 32). Generally, the wavelength λ of the SAW excited by the IDT electrode 3 can be defined as a length twice the electrode finger pitch p. In the following, λ=2p is defined.

[0108] In addition, in this specification, the length of one of the electrode fingers 32 (the first electrode finger 32a or the second electrode finger 32b) in the x direction is referred to as the width w. The first electrode finger 32a and the second electrode finger 32b may have the same or substantially the same width w. In this specification, "substantially the same" means substantially the same, and a difference (error) in size of about ±5% is allowed. This is also the same in the following description, and repeated description is omitted.

[0109] The width w can be appropriately set, for example, according to the electrical characteristics required by the elastic wave device 100. As an example, the width w can be set according to the electrode finger pitch p. In this specification, the ratio of the width w to the electrode finger pitch p (w / p) is referred to as the duty cycle. The resonator 1 can have a constant width w and an electrode finger pitch p throughout the electrode fingers 32 (i.e., a constant duty cycle). In this specification, "constant" is not limited to strictly no change, but is used to mean an allowable error of about ±5 degrees.

[0110] The electrode finger 32 may be, for example, a thin flat plate formed of a metal material extending in the y direction. For example, the metal may be aluminum (Al), copper (Cu), or platinum (Pt). The structure (material and thickness) of the electrode finger 32 will be described in more detail later.

[0111] The IDT electrode 3 may further include a protective layer covering the electrode fingers 32. The material of the protective layer may be SiO2, for example, and any insulating material generally used as a protective film may be used as appropriate.

[0112] The elastic wave device 100 may include a pair of reflectors 4a and 4b corresponding to the IDT electrode 3. In this specification, the reflectors 4a and 4b are also collectively referred to as the reflectors 4. The reflectors 4 may be positioned so as to sandwich the IDT electrode 3 in the x direction.

[0113] <Overview of the Knowledge Disclosed>

[0114] In communication equipment, etc., a relatively low frequency band is used for communication, such as a band of 700 MHz to 900 MHz (hereinafter, for ease of explanation, sometimes referred to as the "target band"). The value calculated by dividing the bandwidth (passband width) by the center frequency (resonant frequency) is called the specific bandwidth (sometimes referred to as the "specific bandwidth Δf" in this specification). The minimum value of the specific bandwidth Δf of various existing communication bands using the target band is 1.1% in the downlink communication of Band 6. Therefore, the inventors set a bandwidth in the target band and a specific bandwidth Δf of 1.1% or more as the conditions required for the filter characteristics of the elastic wave device 100.

[0115] In addition, further miniaturization is required for the elastic wave device 100 installed in communication equipment and the like that utilizes the above-mentioned target frequency band. Here, it is known that, in general, Lamb waves having a vibration plane perpendicular to the surface of the piezoelectric layer 2 are one of various propagation modes in SAW and have multi-mode properties. The asymmetric 0th-order mode Lamb wave (also called "A0-mode Lamb wave") among Lamb waves has a lower sound velocity than various general SAWs. In this specification, "sound velocity" is the propagation velocity of the elastic wave utilized in the elastic wave device 100, and may also be referred to as the phase velocity.

[0116] The inventors of the present invention have come up with the idea of ​​reducing the acoustic velocity V by utilizing the A0 mode Lamb wave, thereby miniaturizing the elastic wave device 100. The acoustic velocity V of the A0 mode Lamb wave decreases as the thickness of the piezoelectric layer 2 decreases. However, an elastic wave device 100 that utilizes the A0 mode Lamb wave and satisfies the condition that the specific bandwidth Δf in the target frequency band is 1.1% or more is not known, and the specific conditions required for the elastic wave device 100 are unclear.

[0117] The present inventors used the finite element method (FEM) simulation for the elastic wave device 100 having the above-described basic structure (bonding structure) to evaluate the relationship between the specific structure and the filter characteristics. Moreover, the inventors found the conditions stipulated for the structure of the elastic wave device 100, and thus conceived the present invention. Hereinafter, the structure of the resonator 1 in the elastic wave device 100, which satisfies the stipulated conditions for the characteristics of the fractional bandwidth Δf and the sound velocity V, as a result of the exploration by the present inventors using FEM simulation, will be described.

[0118] <Basic Structure of FEM Simulation>

[0119] Figure 3 It is a diagram showing an outline of the FEM simulation model of the elastic wave device. Figure 4 It is a table showing the FEM simulation conditions. As Figure 3 shown, in the FEM simulation model SM of the elastic wave device, a piezoelectric layer 2 is bonded via an intermediate layer 6 above a support substrate 5, and has a first electrode finger 32a and a second electrode finger 32b on the surface of the piezoelectric layer 2.

[0120] In Figure 4 the conditions shown, FEM simulation is performed. The material of the electrode fingers 32 is Al, Cu, or Pt. The material of the piezoelectric layer 2 is LT (LiTaO3) or LN (LiNbO3). The thickness of the electrode fingers 32, the thickness of the piezoelectric layer 2, the cut angle, and the propagation angle are variables. In addition, in the FEM simulation, the electrode finger pitch p is fixed at 1.0 μm, and the duty ratio is fixed at 0.5. The wavelength λ of the asymmetric zero-order mode Lamb wave is twice the electrode finger pitch p, which is 2.0 μm.

[0121] Here, in the preliminary FEM simulation, the thickness of the intermediate layer 6 has no significant influence on the filter characteristics. Therefore, in the FEM simulation described below, the material of the intermediate layer 6 is set to SiO2, and the thickness is fixed at a general value of 0.5λ.

[0122] The Euler angles of the piezoelectric layer 2 can generally be expressed as ( θ, ψ). In the FEM simulation described below, is fixed at 0°, and θ and ψ are variables. The meanings of θ and ψ in the Euler angles of the piezoelectric layer 2 can be understood based on common technical knowledge. For simplicity, the detailed description of the Euler angles of the piezoelectric layer 2 is omitted.

[0123] In each of the multiple FEM simulation results described below, the condition range for each variable and the center point CP within the range are determined. In this specification, the "center point CP" is not the middle value of the range, but a value selected in consideration of the balance of the characteristics of the specific bandwidth Δf and the sound speed V. The reason for its selection will be described later in each FEM simulation result.

[0124] <Study Example 1: LT Film and Al Electrode>

[0125] In Study Example 1, the FEM simulation was performed by using Al as the electrode material and using the LT film as the piezoelectric layer 2 .

[0126] (Al electrode thickness)

[0127] Figure 5A This is a table showing FEM simulation conditions related to the Al electrode thickness in Study Example 1. Figure 5B This is a diagram showing the results of FEM simulation of the relationship between the Al electrode thickness and the specific bandwidth Δf in Investigation Example 1. Figure 5C This is a diagram showing the FEM simulation results of the relationship between the Al electrode thickness and the acoustic velocity V in Study Example 1. In the FEM simulation related to the Al electrode thickness in Study Example 1, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°). In addition, the LT thickness was fixed to 50%λ.

[0128] like Figures 5A to 5C As shown in the figure, it can be seen that when the Al electrode thickness is in the range of 0.6%λ or more and 50.0%λ or less, the specific bandwidth Δf is 1.1%fr or more. As for the relationship between the acoustic velocity V and the Al electrode thickness, it can be seen that the acoustic velocity V tends to decrease as the Al electrode thickness increases. Figure 5B The portion of the maximum point in the fitting curve of the plot of the specific bandwidth Δf shown is set as the center point CP. That is, the center point CP of the thickness of the Al electrode in Study Example 1 is set to 30%λ.

[0129] In this specification, the unit of the specific bandwidth Δf may be expressed as “% fr.” This means that the bandwidth is expressed as a percentage of a value calculated by dividing the resonant frequency (fr).

[0130] (LT thickness)

[0131] Fig. 6A This is a table showing FEM simulation conditions related to LT thickness in Study Example 1. Figure 6B This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the specific bandwidth Δf in Investigation Example 1. Figure 6CThis is a diagram showing the FEM simulation results of the relationship between the LT thickness and the sound velocity V in Study Example 1. In the FEM simulation related to the LT thickness in Study Example 1, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°), and the Al electrode thickness was fixed to the center point CP in the above-mentioned FEM simulation results, that is, 30%λ.

[0132] like Figures 6A to 6C As shown in the figure, it can be seen that within the range of LT thickness of 20.0%λ or more, the specific bandwidth Δf is 1.1%fr or more. In addition, within the range of LT thickness of 20.0%λ or more, as the LT thickness increases, the sound velocity V increases, and the value of the sound velocity V is saturated when the LT thickness is 87.5%λ. Based on this result, a point with a larger specific bandwidth Δf and a slower sound velocity B is selected as the center point CP. That is, the center point CP of the LT thickness in Study Example 1 is set to 32.5%λ.

[0133] (LT cut corners)

[0134] Fig. 7A This is a table showing FEM simulation conditions related to the LT cut angle in Study Example 1. Figure 7B This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the specific bandwidth Δf in Investigation Example 1. Figure 7C This is a diagram showing the FEM simulation results of the relationship between the LT cut angle and the sound velocity V in Study Example 1. In the FEM simulation related to the LT cut angle in Study Example 1, the Al electrode thickness was fixed to the center point CP in the above FEM simulation results, that is, 30%λ, and the LT thickness was fixed to the center point CP in the above FEM simulation results, that is, 32.5%λ.

[0135] like Figures 7A to 7C As shown in the figure, it can be seen that when the LT cut angle is within the range of 8° or more and 74° or less, the bandwidth Δf is greater than 1.1% fr. In order to be consistent with the exploration in other FEM simulations, the center point CP of the LT cut angle is set to 36°. Figure 7B As shown in FIG. 1 , it can be seen that the center point CP of the LT cut angle is located near the maximum point on the fitting curve of the plot of the specific bandwidth Δf.

[0136] (LT propagation angle)

[0137] Fig. 8A This is a table showing FEM simulation conditions related to the LT propagation angle in Study Example 1. Figure 8B This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the specific bandwidth Δf in Investigation Example 1. Figure 8CThis is a diagram showing the FEM simulation results of the relationship between the LT propagation angle and the sound velocity V in Study Example 1. In the FEM simulation related to the LT propagation angle in Study Example 1, the Al electrode thickness was fixed to 30%λ, which is the center point CP in the above FEM simulation results. In addition, the LT thickness was fixed to 32.5%λ, which is the center point CP in the above FEM simulation results, and the LT cut angle was fixed to 36°.

[0138] like Figures 8A to 8C As shown, it can be seen that in the range of LT propagation angles of 0° to 26° and 154° to 180°, in other words, in the range of LT propagation angles of -26° to 26°, the bandwidth Δf is 1.1% fr or more. Figure 8B In the fitting curve of the plot of the specific bandwidth Δf shown, 0° and 180° of the LT propagation angle are equivalent, so there is actually a peak that is convex upward. The part of the maximum point of the fitting curve is selected as the center point CP. That is, the center point CP of the LT propagation angle is set to 0°.

[0139] <Configuration Example 1>

[0140] In the elastic wave device 100 in the configuration example 1 of the present embodiment based on the FEM simulation results of the above-mentioned study example 1, the main component of the constituent material of the piezoelectric layer 2 is lithium tantalate (LT), and the thickness is 20.0%λ or more and 87.5%λ or less. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), is greater than -5° and less than 5°, θ is greater than 8° and less than 74°, and ψ is greater than -26° and less than 26°. The main component of the material constituting the IDT electrode 3 is Al, and the thickness is greater than 0.6%λ and less than 50.0%λ. The above-mentioned λ is the wavelength λ of the A0 mode Lamb wave, which is defined as: a length twice the pitch p of the plurality of electrode fingers 32 included in the IDT electrode 3. The definition of the above-mentioned λ is the same in the following description of this specification, and repeated description is omitted.

[0141] From the viewpoint of allowing for errors in the manufacturing process, the Euler angles of the piezoelectric layer 2 are The regulation is: within the range of -5° and below 5°. In the range of -5° to 5°, the characteristics of elastic wave device 100 hardly change.

[0142] In elastic wave device 100 of Configuration Example 1, A0 mode Lamb waves can be efficiently excited or received by resonator 1. Elastic wave device 100 of Configuration Example 1 functions as a SAW filter using the A0 mode Lamb waves and has a frequency characteristic with a specific bandwidth Δf of 1.1% fr or more.

[0143] Here, the acoustic velocity V of the conventional SAW is about 4000 m / s, and the acoustic velocity V of the A0 mode Lamb wave is slower than that of the conventional SAW. For example, by comparing the elastic wave device 100 having a certain resonance frequency with an elastic wave device (conventional elastic wave device) having the same resonance frequency using the conventional SAW, the following can be obtained. That is, since the acoustic velocity V of the A0 mode Lamb wave is smaller than that of the conventional SAW, the elastic wave device 100 can reduce the electrode finger pitch p compared with the conventional elastic wave device according to V=fλ (f: constant) and λ=2p. For example, assuming that the resonance frequency fr is 1000 MHz, the electrode finger pitch p is 2 μm when V=4000 m / s, and the electrode finger pitch p is 1 μm when V=2000 m / s. If the total number of electrode fingers 32 is the same, the smaller the electrode finger pitch p is, the more compact the size of the IDT electrode 3 can be.

[0144] According to elastic wave device 100 in configuration example 1, resonator 1 can be miniaturized by utilizing A0 mode Lamb waves that propagate at a slower acoustic velocity V than conventional SAW. As a result, elastic wave device 100 can be miniaturized while having a frequency characteristic with a specific bandwidth Δf of 1.1% fr or more.

[0145] (Supplementary matters)

[0146] In the present embodiment, “the main component of the constituent material is component A” means that the ratio of component A to the entire constituent material is greater than 50% by mass. This also applies to the following description of this specification, and repeated description is omitted.

[0147] In the elastic wave device 100 in the configuration example 1 of the present embodiment, the piezoelectric layer 2 may be composed of LT or substantially composed of LT. In addition, the IDT electrode 3 may be composed of Al or substantially composed of Al. In the present embodiment, "substantially composed of component B" means that the ratio of the above-mentioned component B to the whole constituent material is 90 mass % or more. This is also the same in the following description of this specification, and repeated description is omitted.

[0148] Without being limited to the above example, in the elastic wave device 100 in the configuration example 1 of the present embodiment, the piezoelectric layer 2 may contain 70% by mass or more of LT, or may contain 80% by mass or more of LT. The remainder of the constituent material of the piezoelectric layer 2 other than LT may be composed of any additive components and unavoidable impurities.

[0149] In elastic wave device 100 in Configuration Example 1 of the present embodiment, IDT electrode 3 may contain 70 mass % or more of Al, or 80 mass % or more of Al. The remainder of the constituent material of IDT electrode 3 other than Al may be composed of any additive components and unavoidable impurities.

[0150] <Study Example 2: LT membrane and Cu electrode>

[0151] In Study Example 2, FEM simulation was performed by using Cu as the electrode material and using an LT film as the piezoelectric layer 2 .

[0152] (Cu electrode thickness)

[0153] Fig.9A This is a table showing FEM simulation conditions related to the Cu electrode thickness in Investigation Example 2. Fig. 9B This is a diagram showing the results of FEM simulation of the relationship between the Cu electrode thickness and the specific bandwidth Δf in Investigation Example 2. Fig. 9C It is a diagram showing the results of FEM simulation on the relationship between the Cu electrode thickness and the acoustic velocity V in Study Example 2. In the FEM simulation on the Cu electrode thickness in Study Example 2, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°).

[0154] like Figures 9A to 9C As shown, it can be seen that when the Cu electrode thickness is in the range of 0.2%λ or more and 50.0%λ or less, the specific bandwidth Δf is 1.1%fr or more. As for the relationship between the sound velocity V and the Cu electrode thickness, it can be seen that the sound velocity V tends to decrease as the Cu electrode thickness increases. Fig. 9B The portion of the maximum point in the fitting curve of the plot of the specific bandwidth Δf shown is set as the center point CP. That is, the center point CP of the thickness of the Cu electrode in Study Example 2 is set to 20%λ.

[0155] (LT thickness)

[0156] Fig. 10A This is a table showing FEM simulation conditions related to LT thickness in Investigation Example 2. Fig. 10B This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the specific bandwidth Δf in Investigation Example 2. Fig. 10C This is a diagram showing the FEM simulation results of the relationship between the LT thickness and the sound velocity V in Study Example 2. In the FEM simulation related to the LT thickness in Study Example 2, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°), and the Cu electrode thickness was fixed to the center point CP in the above-mentioned FEM simulation results, that is, 20%λ.

[0157] like Figures 10A to 10CAs shown in the figure, it can be seen that within the range of LT thickness of 17.5%λ or more, the specific bandwidth Δf is 1.1%fr or more. In addition, within the range of LT thickness of 17.5%λ or more, as the LT thickness increases, the sound velocity V increases, and the value of the sound velocity V is saturated when the LT thickness is 90.0%λ. Based on this result, a point with a larger specific bandwidth Δf and a slower sound velocity B is selected as the center point CP. That is, the center point CP of the LT thickness in Study Example 2 is set to 37.5%λ.

[0158] (LT cut corners)

[0159] Fig.11A This is a table showing FEM simulation conditions related to the LT cut angle in Study Example 2. Fig. 11B This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the specific bandwidth Δf in Investigation Example 2. Fig. 11C This is a diagram showing the FEM simulation results of the relationship between the LT cut angle and the sound velocity V in Study Example 2. In the FEM simulation related to the LT cut angle in Study Example 2, the Cu electrode thickness was fixed to 20%λ, which is the center point CP in the above FEM simulation results, and the LT thickness was fixed to 37.5%λ, which is the center point CP in the above FEM simulation results.

[0160] like Figures 11A to 11C As shown in the figure, it can be seen that in the range of LT cutting angles of 0° to 80° and 160° to 180°, in other words, in the range of LT cutting angles of -20° to 80°, the specific bandwidth Δf is 1.1% fr or more. In order to be consistent with the exploration in other FEM simulations, the center point CP of the LT cutting angle is set to 36°. Fig. 11B As shown in FIG. 1 , it can be seen that the center point CP of the LT cut angle is located near the maximum point on the fitting curve of the plot of the specific bandwidth Δf.

[0161] (LT propagation angle)

[0162] Fig. 12A This is a table showing FEM simulation conditions related to the LT propagation angle in Investigation Example 2. Fig. 12B This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the specific bandwidth Δf in Investigation Example 2. Fig. 12C This is a diagram showing the FEM simulation results of the relationship between the LT propagation angle and the sound velocity V in the study example 2. In the FEM simulation related to the LT propagation angle in the study example 2, the Cu electrode thickness was fixed to 20%λ, which is the center point CP in the above FEM simulation results. In addition, the LT thickness was fixed to 37.5%λ, which is the center point CP in the above FEM simulation results, and the LT cut angle was fixed to 36°.

[0163] like Figures 12A to 12CAs shown, it can be seen that in the range of LT propagation angles of 0° to 40° and 140° to 180°, in other words, in the range of LT propagation angles of -40° to 40°, the bandwidth Δf is 1.1% fr or more. Fig. 12B On the fitting curve of the plot of the specific bandwidth Δf shown, 0° and 180° of the LT propagation angle are equivalent, so there is actually a peak that is convex upward. The part of the maximum point of the fitting curve is selected as the center point CP. That is, the center point CP of the LT propagation angle is set to 0°.

[0164] <Configuration Example 2>

[0165] In the elastic wave device 100 in the configuration example 2 of the present embodiment based on the FEM simulation results of the above-mentioned study example 2, the main component of the constituent material of the piezoelectric layer 2 is lithium tantalate (LT), and the thickness is 17.5%λ or more and 90.0%λ or less. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), is between -5° and 5°, θ is between -20° and 80°, and ψ is between -40° and 40°. The main component of the material of the IDT electrode 3 is Cu, and the thickness is between 0.2%λ and 58.0%λ. From the perspective of tolerance of the manufacturing process, the Euler angles of the piezoelectric layer 2 are The regulation is: within the range of -5° to 5°.

[0166] In the elastic wave device 100 in the configuration example 2 of the present embodiment, the piezoelectric layer 2 may be the same as that in the configuration example 1 described above. In addition, the IDT electrode 3 may be composed of Cu, or may be substantially composed of Cu. The IDT electrode 3 may contain 70% by mass or more of Cu, or may contain 80% by mass or more of Cu. The remainder of the constituent material of the IDT electrode 3 other than Cu may be composed of any additive component and unavoidable impurities.

[0167] In the elastic wave device 100 of the configuration example 2, the A0 mode Lamb wave can also be effectively excited or received by the resonator 1. By utilizing the A0 mode Lamb wave that propagates at a sound velocity V slower than that of the conventional SAW, the resonator 1 can be miniaturized. As a result, the elastic wave device 100 can be miniaturized while having a frequency characteristic with a specific bandwidth Δf of 1.1% fr or more. The repeated description of this is omitted, but the same is true in the following configuration examples 3 to 8.

[0168] <Study Example 3: LT Film and Pt Electrode>

[0169] In Study Example 3, FEM simulation was performed by using Pt as the electrode material and an LT film as the piezoelectric layer 2 .

[0170] (Pt electrode thickness)

[0171] Fig.13A This is a table showing FEM simulation conditions related to the Pt electrode thickness in Investigation Example 3. Fig. 13B This is a diagram showing the results of FEM simulation of the relationship between the Pt electrode thickness and the specific bandwidth Δf in Investigation Example 3. Fig. 13C It is a diagram showing the results of FEM simulation on the relationship between the Pt electrode thickness and the acoustic velocity V in Investigation Example 3. In the FEM simulation on the Pt electrode thickness in Investigation Example 3, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°).

[0172] like Figures 13A to 13C As shown, it can be seen that when the Pt electrode thickness is in the range of 0.3%λ or more and 74.0%λ or less, the specific bandwidth Δf is 1.1%fr or more. As for the relationship between the sound velocity V and the Pt electrode thickness, it can be seen that the sound velocity V tends to decrease as the Pt electrode thickness increases. Fig. 13B The portion of the maximum point in the fitting curve of the plot of the specific bandwidth Δf shown is set as the center point CP. That is, the center point CP of the thickness of the Pt electrode in Study Example 3 is set to 13%λ.

[0173] (LT thickness)

[0174] Fig.14A This is a table showing FEM simulation conditions related to LT thickness in Investigation Example 3. Fig. 14B This is a diagram showing the results of FEM simulation of the relationship between the LT thickness and the specific bandwidth Δf in Investigation Example 3. Fig. 14C This is a diagram showing the FEM simulation results of the relationship between the LT thickness and the sound velocity V in Study Example 3. In the FEM simulation related to the LT thickness in Study Example 3, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°), and the Pt electrode thickness was fixed to the center point CP in the above-mentioned FEM simulation results, that is, 13%λ.

[0175] like Figures 14A to 14C As shown in the figure, it can be seen that within the range of LT thickness of 15.0%λ or more, the specific bandwidth Δf is 1.1%fr or more. In addition, within the range of LT thickness of 15.0%λ or more, as the LT thickness increases, the sound velocity V increases, and the value of the sound velocity V is saturated when the LT thickness is 85.0%λ. Based on this result, a point with a larger specific bandwidth Δf and a slower sound velocity B is selected as the center point CP. That is, the center point CP of the LT thickness in Study Example 3 is set to 40.0%λ.

[0176] (LT cut corners)

[0177] Fig.15AThis is a table showing FEM simulation conditions related to the LT cut angle in Investigation Example 3. Fig. 15B This is a diagram showing the results of FEM simulation of the relationship between the LT cut angle and the specific bandwidth Δf in Investigation Example 3. Fig. 15C This is a diagram showing the FEM simulation results of the relationship between the LT cut angle and the sound velocity V in the study example 3. In the FEM simulation related to the LT cut angle in the study example 3, the Pt electrode thickness was fixed to 13%λ, which is the center point CP in the above FEM simulation results. In addition, the LT thickness was fixed to 40.0%λ, which is the center point CP in the above FEM simulation results.

[0178] like Figures 15A to 15C As shown in the figure, it can be seen that in the range of LT cutting angles of 0° to 86° and 140° to 180°, in other words, in the range of LT cutting angles of -40° to 86°, the bandwidth ratio Δf is 1.1% fr or more. In order to be consistent with the exploration in other FEM simulations, the center point CP of the LT cutting angle is set to 36°. Fig. 15B As shown in FIG. 1 , it can be seen that the center point CP of the LT cut angle is located near the maximum point on the fitting curve of the plot of the specific bandwidth Δf.

[0179] (LT propagation angle)

[0180] Fig.16A This is a table showing FEM simulation conditions related to the LT propagation angle in Investigation Example 3. Fig. 16B This is a diagram showing the results of FEM simulation of the relationship between the LT propagation angle and the specific bandwidth Δf in Investigation Example 3. Fig. 16C This is a diagram showing the FEM simulation results of the relationship between the LT propagation angle and the sound velocity V in the study example 3. In the FEM simulation related to the LT propagation angle in the study example 3, the Pt electrode thickness was fixed to 13%λ, which is the center point CP in the above FEM simulation results. In addition, the LT thickness was fixed to 40.0%λ, which is the center point CP in the above FEM simulation results, and the LT cut angle was fixed to 36°.

[0181] like Figures 16A to 16C As shown, it can be seen that in the range of LT propagation angles of 0° to 50° and 130° to 180°, in other words, in the range of LT propagation angles of -50° to 50°, the bandwidth Δf is 1.1% fr or more. Fig. 16B On the fitting curve of the plot of the specific bandwidth Δf shown, 0° and 180° of the LT propagation angle are equivalent, so there is actually a peak that is convex upward. The part of the maximum point of the fitting curve is selected as the center point CP. That is, the center point CP of the LT propagation angle is set to 0°.

[0182] <Configuration Example 3>

[0183] In the elastic wave device 100 in the configuration example 3 of the present embodiment based on the FEM simulation results of the above-mentioned study example 3, the main component of the constituent material of the piezoelectric layer 2 is lithium tantalate (LT), and the thickness is 15.0%λ or more and 85.0%λ or less. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), is between -5° and 5°, θ is between -40° and 86°, and ψ is between -50° and 50°. The main component of the material constituting the IDT electrode 3 is Pt, and the thickness is between 0.3%λ and 74.0%λ. From the perspective of tolerance of the manufacturing process, the Euler angles of the piezoelectric layer 2 are The regulation is: within the range of -5° to 5°.

[0184] In the elastic wave device 100 in the configuration example 3 of the present embodiment, the piezoelectric layer 2 may be the same as that in the configuration example 1 described above. In addition, the IDT electrode 3 may be composed of Pt, or may be substantially composed of Pt. The IDT electrode 3 may contain 70% by mass or more of Pt, or may contain 80% by mass or more of Pt. The remainder of the constituent material of the IDT electrode 3 other than Pt may be composed of any additive component and unavoidable impurities.

[0185] <Study Example 4: LT Film and Metal Electrode>

[0186] In the above-mentioned research examples 1 to 3, the electrode materials were set to Al, Cu, and Pt, respectively, and the piezoelectric layer 2 was set to LT film. In contrast, in research example 4, based on the results of the above-mentioned research examples 1 to 3, the electrode material constituting the IDT electrode 3 was further studied when the piezoelectric layer 2 was set to LT film.

[0187] Fig.17A This is a table showing the shear wave sound speed of major metal materials. Fig. 17B is a diagram showing the calculation formula for the shear wave speed of sound. Fig. 17B In the formula, V is the transverse wave speed (m / s), E is the Young's modulus (Pa), and ρ is the density (kg / m 3 ), γ is the Poisson’s ratio.

[0188] like Fig.17A As shown, it can be seen that the shear wave sound velocities of Al, Cu, and Pt used in the above-mentioned Study Examples 1 to 3 are 2571 m / s, 1804 m / s, and 1244 m / s, respectively.

[0189] In the above-mentioned Study Example 1, the center point CP of the Al electrode thickness is 30%λ, the sound velocity (elastic wave sound velocity) V at the center point CP is about 3000m / s, and the specific bandwidth Δf at the center point CP is about 1.6 (refer to Figure 5A to Figure 5C ). In addition, in the above-mentioned Study Example 2, the center point CP of the Cu electrode thickness is 20%λ, the sound velocity (elastic wave sound velocity) V at the center point CP is about 2500m / s, and the specific bandwidth Δf at the center point CP is about 2.1 (refer to Figures 9A to 9C In the above-mentioned Study Example 3, the center point CP of the Pt electrode thickness is 13%λ, the sound velocity (elastic wave sound velocity) V at the center point CP is about 2300m / s, and the specific bandwidth Δf at the center point CP is about 2.5 (refer to Figures 13A to 13C ).

[0190] Fig.18A This is a diagram showing the relationship between the transverse wave sound velocity of the electrode material and the center point CP of the electrode thickness in the results of the investigation of Examples 1 to 3. Fig.18B This is a graph showing the relationship between the transverse wave velocity and the sound velocity (elastic wave velocity) V of the electrode material in the results of the investigation of Examples 1 to 3. Fig.18C This is a graph showing the relationship between the transverse wave sound velocity and the specific bandwidth Δf of the electrode material in the results of the investigation of Examples 1 to 3. Figures 18A to 18C The straight lines and coefficients of determination calculated by approximating the plots corresponding to the results of Study Examples 1 to 3 with a linear function are shown in FIG. Figures 18A to 18C As shown, it can be seen that the transverse wave sound velocity and sound velocity (elastic wave sound velocity) V of the electrode material and the specific bandwidth Δf have a linear function relationship with each other.

[0191] like Fig.18C As shown in the figure, it can be seen that when the transverse wave velocity of the electrode material is below 3473m / s, the bandwidth Δf is above 1.1%fr. In an electrode using an electrode material with a low transverse wave velocity, energy tends to concentrate around the electrode, resulting in a larger bandwidth Δf. Fig.17A As shown in Figure 1, Au has the slowest transverse wave velocity among the main metal materials, which is 658 m / s. Based on this, the lower limit of the transverse wave velocity of the electrode material is set to 500 m / s.

[0192] <Configuration Example 4>

[0193] In the elastic wave device 100 in the configuration example 4 of the present embodiment based on the FEM simulation results of the above-mentioned discussion examples 1 to 3 and the above-mentioned discussion results, the main component of the constituent material of the piezoelectric layer 2 is lithium tantalate, and the thickness is 15.0%λ or more and 90.0%λ or less. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), The IDT electrode 3 is mainly composed of a metal having a transverse wave sound velocity of 500 m / s to 3473 m / s, and has a thickness of 0.2%λ to 74.0%λ.

[0194] In the elastic wave device 100 of another example of the configuration example 4 of the present embodiment based on the FEM simulation results of the above-mentioned discussion examples 1 to 3 and the above-mentioned discussion results, the main component of the constituent material of the piezoelectric layer 2 is lithium tantalate, and the thickness is not less than 20.0%λ and not more than 85.0%λ. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), The IDT electrode 3 is mainly composed of a metal having a transverse wave sound velocity of 500 m / s to 3473 m / s, and has a thickness of 0.6%λ to 50.0%λ.

[0195] In the elastic wave device 100 of Configuration Example 4 of the present embodiment or other examples thereof, the piezoelectric layer 2 may be the same as that of the above-mentioned Configuration Example 1. In addition, the IDT electrode 3 may be composed of a metal having a transverse wave sound velocity of 500 m / s or more and 3473 m / s or less (hereinafter referred to as "specific metal M1"), or may be substantially composed of the specific metal M1, and the main component of the constituent material may be the specific metal M1.

[0196] The main component of the constituent material of the IDT electrode 3 can be determined based on the electrode structure of the IDT electrode 3. For example, in the case where the electrode is a stacked structure, the material with the highest concentration in the thickest layer among the multiple layers constituting the stacked structure can be used as the main component. Alternatively, the average value of the shear wave sound velocity of each material of the multiple layers constituting the stacked structure can be regarded as the shear wave sound velocity of the constituent material of the IDT electrode 3. In this case, the average value can be, for example, within a range of 500 m / s to 3473 m / s. In the case where the electrode is a stacked structure, the sound velocity can be calculated based on volume average, for example.

[0197] Alternatively, the electrode in the IDT electrode 3 may be an alloy. In the case where the electrode is an alloy, the material with the highest concentration in the composition of the alloy may be the main component. The concentration in the composition of the alloy can be measured, for example, using EDX (Energy Dispersive X-ray Spectroscopy) or WDX (wavelength-dispersive X-ray spectroscopy). Alternatively, the transverse wave velocity of the constituent material of the IDT electrode 3 calculated based on the density, Young's modulus, and Poisson's ratio of the alloy may be, for example, within a range of 500 m / s to 3473 m / s. The Poisson's ratio is, for example, 0.3 in various alloys.

[0198] <Exploration Example 5: LN Film and Al Electrode>

[0199] Next, in Study Example 5, FEM simulation was performed by using Al as the electrode material and LN film as the piezoelectric layer 2 .

[0200] (Al electrode thickness)

[0201] Fig.19A This is a table showing FEM simulation conditions related to the Al electrode thickness in Investigation Example 5. Fig.19B This is a diagram showing the results of FEM simulation of the relationship between the Al electrode thickness and the specific bandwidth Δf in Investigation Example 5. Fig.19C It is a diagram showing the results of FEM simulation on the relationship between the Al electrode thickness and the acoustic velocity V in Investigation Example 5. In the FEM simulation on the Al electrode thickness in Investigation Example 5, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°).

[0202] like Figures 19A to 19C As shown, it can be seen that within the range where the Al electrode thickness is less than 100% λ, the specific bandwidth Δf is greater than 1.1% fr. An Al electrode thickness exceeding 100% λ is unrealistic, and an Al electrode thickness that is too thin is also unrealistic. Therefore, the range of the Al electrode thickness can be specified to be greater than 0.05% λ and less than 100.0% λ. As a range where the value of the specific bandwidth Δf becomes greater than the value when the Al electrode thickness is 0.05% λ, the range of the Al electrode thickness can be specified to be greater than 0.05% λ and less than 50.0% λ.

[0203] choose Fig.19B The portion of the maximum point in the fitting curve of the plot of the specific bandwidth Δf shown is set as the center point CP. That is, the center point CP of the thickness of the Al electrode in Study Example 5 is set to 24%λ.

[0204] (LN thickness)

[0205] Fig. 20A This is a table showing FEM simulation conditions related to LN thickness in Investigation Example 5. Fig. 20B This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the specific bandwidth Δf in Investigation Example 5. Fig. 20C This is a diagram showing the FEM simulation results of the relationship between the LN thickness and the sound velocity V in Study Example 5. In the FEM simulation related to the LN thickness in Study Example 5, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°), and the Al electrode thickness was fixed to the center point CP in the above-mentioned FEM simulation results, that is, 24%λ.

[0206] like Figures 20A to 20C As shown in the figure, it can be seen that in the range of LN thickness of 10.0%λ or more, the specific bandwidth Δf is 1.1%fr or more. In addition, in the range of LN thickness of 10.0%λ or more, as the LN thickness increases, the sound velocity V increases, and the value of the sound velocity V is saturated when the LN thickness is 92.5%λ. Based on this result, a point with a larger specific bandwidth Δf and a slower sound velocity B is selected as the center point CP. That is, the center point CP of the LN thickness in Study Example 5 is set to 35.0%λ.

[0207] (LN cutting angle)

[0208] Fig.21A This is a table showing FEM simulation conditions related to the LN cut angle in Investigation Example 5. Fig.21B This is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the specific bandwidth Δf in Investigation Example 5. Fig. 21C This is a diagram showing the FEM simulation results of the relationship between the LN cutting angle and the sound velocity V in Study Example 5. In the FEM simulation related to the LN cutting angle in Study Example 5, the Al electrode thickness was fixed to 24%λ, which is the center point CP in the above FEM simulation results, and the LN thickness was fixed to 35.0%λ, which is the center point CP in the above FEM simulation results.

[0209] like Figures 21A to 21C As shown in the figure, it can be seen that in the range of LN cutting angles of 0° to 90° and 142° to 180°, in other words, in the range of LN cutting angles of -38° to 90°, the specific bandwidth Δf is 1.1% fr or more. In order to be consistent with the exploration in other FEM simulations, the center point CP of the LN cutting angle is set to 36°. Fig.21B As shown, it can be seen that the center point CP of the LN cut angle is located near the maximum point on the fitting curve of the plot of the specific bandwidth Δf.

[0210] (LN propagation angle)

[0211] Fig.22A This is a table showing FEM simulation conditions related to the LN propagation angle in Study Example 5. Fig. 22B 1 is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the specific bandwidth Δf in Investigation Example 5. Fig. 22C This is a diagram showing the FEM simulation results of the relationship between the LN propagation angle and the sound velocity V in Study Example 5. In the FEM simulation related to the LN propagation angle in Study Example 5, the Al electrode thickness was fixed to 24%λ, which is the center point CP in the above FEM simulation results. In addition, the LN thickness was fixed to 35.0%λ, which is the center point CP in the above FEM simulation results, and the LN cut angle was fixed to 36°.

[0212] like Figures 22A to 22C As shown, it can be seen that in the range of the LN propagation angle being greater than 0° and less than 50° and greater than 130° and less than 180°, in other words, in the range of the LN propagation angle being greater than -50° and less than 50°, the specific bandwidth Δf is greater than 1.1% fr. Fig. 22B On the fitting curve of the plot of the specific bandwidth Δf shown, 0° and 180° of the LN propagation angle are equivalent, so there is actually a peak that is convex upward. The part of the maximum point of the fitting curve is selected as the center point CP. That is, the center point CP of the LN propagation angle is set to 0°.

[0213] <Configuration Example 5>

[0214] In the elastic wave device 100 in the configuration example 5 of the present embodiment based on the FEM simulation results of the above-mentioned research example 5, the main component of the constituent material of the piezoelectric layer 2 is lithium niobate, and the thickness is not less than 10.0%λ and not more than 92.5%λ. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), is -5° to 5°, θ is -38° to 90°, and ψ is -50° to 50°. The main component of the material constituting the IDT electrode 3 is Al, and the thickness is 0.05%λ to 100.0%λ.

[0215] In the elastic wave device 100 in the configuration example 5 of the present embodiment, the piezoelectric layer 2 may be composed of LN or may be substantially composed of LN. The piezoelectric layer 2 may contain 70% by mass or more of LN or may contain 80% by mass or more of LN. The remainder of the constituent material of the piezoelectric layer 2 other than LN may be composed of any additive component and unavoidable impurities.

[0216] In addition, the IDT electrode 3 may be composed of Al or substantially composed of Al. The IDT electrode 3 may contain 70% by mass or more of Al or 80% by mass or more of Al. The remainder of the constituent material of the IDT electrode 3 other than Al may be composed of any additive component and unavoidable impurities.

[0217] <Study Example 6: LN Film and Cu Electrode>

[0218] In Study Example 6, FEM simulation was performed by using Cu as the electrode material and LN film as the piezoelectric layer 2 .

[0219] (Cu electrode thickness)

[0220] Fig.23A This is a table showing FEM simulation conditions related to the Cu electrode thickness in Investigation Example 6. Fig. 23B This is a diagram showing the results of FEM simulation of the relationship between the Cu electrode thickness and the specific bandwidth Δf in Investigation Example 6. Fig.23C It is a diagram showing the results of FEM simulation on the relationship between the Cu electrode thickness and the acoustic velocity V in Investigation Example 6. In the FEM simulation on the Cu electrode thickness in Investigation Example 6, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°).

[0221] like Figures 23A to 23C As shown, it can be seen that within the range where the Cu electrode thickness is less than 100%λ, the specific bandwidth Δf is greater than 1.1%fr. A Cu electrode thickness exceeding 100%λ is unrealistic, and a Cu electrode thickness that is too thin is also unrealistic. Therefore, the range of the Cu electrode thickness can be specified to be greater than 0.05%λ and less than 100.0%λ. As a range where the value of the specific bandwidth Δf becomes greater than the value when the Cu electrode thickness is 0.05%λ, the range of the Cu electrode thickness can also be specified to be greater than 0.05%λ and less than 66.0%λ.

[0222] choose Fig. 23B The portion of the maximum point in the fitting curve of the plot of the specific bandwidth Δf shown is set as the center point CP. That is, the center point CP of the thickness of the Cu electrode in Study Example 6 is set to 18%λ.

[0223] (LN thickness)

[0224] Fig.24A This is a table showing FEM simulation conditions related to LN thickness in Investigation Example 6. Fig. 24B This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the specific bandwidth Δf in Investigation Example 6. Fig.24C This is a diagram showing the FEM simulation results of the relationship between the LN thickness and the sound velocity V in Study Example 6. In the FEM simulation related to the LN thickness in Study Example 6, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°), and the Cu electrode thickness was fixed to the center point CP in the above-mentioned FEM simulation results, that is, 18%λ.

[0225] like Figures 24A to 24CAs shown in the figure, it can be seen that within the range of LN thickness of 7.5%λ or more, the specific bandwidth Δf is 1.1%fr or more. In addition, within the range of LN thickness of 7.5%λ or more, as the LN thickness increases, the sound velocity V increases, and when the LN thickness is 85.0%λ, the value of the sound velocity V is saturated. Based on this result, a point with a larger specific bandwidth Δf and a slower sound velocity B is selected as the center point CP. That is, the center point CP of the LN thickness in Study Example 6 is set to 32.5%λ.

[0226] (LN cutting angle)

[0227] Fig.25A This is a table showing FEM simulation conditions related to the LN cut angle in Investigation Example 6. Fig.25B 1 is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the specific bandwidth Δf in Investigation Example 6. Fig.25C This is a diagram showing the FEM simulation results of the relationship between the LN cutting angle and the sound velocity V in Study Example 6. In the FEM simulation related to the LN cutting angle in Study Example 6, the Cu electrode thickness was fixed to 18%λ, which is the center point CP in the above FEM simulation results, and the LN thickness was fixed to 32.5%λ, which is the center point CP in the above FEM simulation results.

[0228] like Figures 25A to 25C As shown in the figure, it can be seen that in the range of LN cutting angles of 0° to 84° and 128° to 180°, in other words, in the range of LN cutting angles of -52° to 84°, the specific bandwidth Δf is 1.1% fr or more. In order to be consistent with the exploration in other FEM simulations, the center point CP of the LN cutting angle is set to 36°. Fig.25B As shown, it can be seen that the center point CP of the LN cut angle is located near the maximum point on the fitting curve of the plot of the specific bandwidth Δf.

[0229] (LN propagation angle)

[0230] Fig.26A This is a table showing FEM simulation conditions related to the LN propagation angle in Study Example 6. Fig.26B This is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the specific bandwidth Δf in Investigation Example 6. Fig.26C This is a diagram showing the FEM simulation results of the relationship between the LN propagation angle and the sound velocity V in Study Example 6. In the FEM simulation related to the LN propagation angle in Study Example 6, the Cu electrode thickness was fixed to 18%λ, which is the center point CP in the above FEM simulation results. In addition, the LN thickness was fixed to 32.5%λ, which is the center point CP in the above FEM simulation results, and the LN cut angle was fixed to 36°.

[0231] like Figures 26A to 26CAs shown, it can be seen that in the range of the LN propagation angle being greater than 0° and less than 58° and greater than 122° and less than 180°, in other words, in the range of the LN propagation angle being greater than -58° and less than 58°, the specific bandwidth Δf is greater than 1.1% fr. Fig.26B In the fitting curve of the plot of the specific bandwidth Δf shown, 0° and 180° of the LN propagation angle are equivalent, so there is actually a peak that is convex upward. The part of the maximum point of the fitting curve is selected as the center point CP. That is, the center point CP of the LN propagation angle is set to 0°.

[0232] <Configuration Example 6>

[0233] In the elastic wave device 100 in the configuration example 6 of the present embodiment based on the above-mentioned FEM simulation results, the main component of the constituent material of the piezoelectric layer 2 is lithium niobate, and the thickness is 7.5%λ or more and 85.0%λ or less. In addition, the Euler angle of the piezoelectric layer 2 is ( θ,ψ), is -5° to 5°, θ is -52° to 84°, and ψ is -58° to 58°. The main component of the material constituting the IDT electrode 3 is Cu, and the thickness is 0.05%λ to 100.0%λ.

[0234] In the elastic wave device 100 in the configuration example 6 of the present embodiment, the piezoelectric layer 2 may be the same as that in the configuration example 5 described above. In addition, the IDT electrode 3 may be composed of Cu, or may be substantially composed of Cu. The IDT electrode 3 may contain 70% by mass or more of Cu, or may contain 80% by mass or more of Cu. The remainder of the constituent material of the IDT electrode 3 other than Cu may be composed of any additive component and unavoidable impurities.

[0235] <Exploration Example 7: LN Film and Pt Electrode>

[0236] In Study Example 7, FEM simulation was performed by using Pt as the electrode material and LN film as the piezoelectric layer 2 .

[0237] (Pt electrode thickness)

[0238] Fig.27A This is a table showing FEM simulation conditions related to the Pt electrode thickness in Investigation Example 7. Fig.27B This is a diagram showing the results of FEM simulation of the relationship between the Pt electrode thickness and the specific bandwidth Δf in Investigation Example 7. Fig.27C It is a diagram showing the results of FEM simulation on the relationship between the Pt electrode thickness and the acoustic velocity V in Investigation Example 7. In the FEM simulation on the Pt electrode thickness in Investigation Example 7, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°).

[0239] like Figures 27A to 27C As shown, it can be seen that within the range where the Pt electrode thickness is less than 100% λ, the specific bandwidth Δf is greater than 1.1% fr. A Pt electrode thickness exceeding 100% λ is unrealistic, and a Pt electrode thickness that is too thin is also unrealistic. Therefore, the range of the Pt electrode thickness can be specified to be greater than 0.05% λ and less than 100.0% λ. As a range where the value of the specific bandwidth Δf becomes greater than the value when the Pt electrode thickness is 0.05% λ, the range of the Pt electrode thickness can also be specified to be greater than 0.05% λ and less than 86.0% λ.

[0240] choose Fig.27B The portion of the maximum point in the fitting curve of the plot of the specific bandwidth Δf shown is set as the center point CP. That is, the center point CP of the thickness of the Pt electrode in Study Example 7 is set to 12%λ.

[0241] (LN thickness)

[0242] Fig.28A This is a table showing FEM simulation conditions related to LN thickness in Investigation Example 7. Fig.28B This is a diagram showing the results of FEM simulation of the relationship between the LN thickness and the specific bandwidth Δf in Investigation Example 7. Fig.28C This is a diagram showing the FEM simulation results of the relationship between the LN thickness and the sound velocity V in Study Example 7. In the FEM simulation related to the LN thickness in Study Example 7, the Euler angles of the piezoelectric layer 2 were fixed to general values ​​(0°, 36°, 0°), and the Pt electrode thickness was fixed to the center point CP in the above-mentioned FEM simulation results, that is, 12%λ.

[0243] like Figures 28A to 28C As shown in the figure, it can be seen that within the range of LN thickness of 7.5%λ or more, the specific bandwidth Δf is 1.1%fr or more. In addition, within the range of LN thickness of 7.5%λ or more, as the LN thickness increases, the sound velocity V increases, and when the LN thickness is 82.5%λ, the value of the sound velocity V is saturated. Based on this result, a point with a larger specific bandwidth Δf and a slower sound velocity B is selected as the center point CP. That is, the center point CP of the LN thickness in Study Example 7 is set to 32.5%λ.

[0244] (LN cutting angle)

[0245] Fig.29A This is a table showing FEM simulation conditions related to the LN cutting angle in Investigation Example 7. Fig.29B 1 is a diagram showing the results of FEM simulation of the relationship between the LN cut angle and the specific bandwidth Δf in Investigation Example 7. Fig.29CThis is a diagram showing the FEM simulation results of the relationship between the LN cutting angle and the sound velocity V in the study example 7. In the FEM simulation related to the LN cutting angle in the study example 7, the Pt electrode thickness was fixed to 12%λ, which is the center point CP in the above FEM simulation results. In addition, the LN thickness was fixed to 32.5%λ, which is the center point CP in the above FEM simulation results.

[0246] like Figures 29A to 29C As shown in the figure, it can be seen that in the range of LN cutting angles of 0° to 86° and 122° to 180°, in other words, in the range of LN cutting angles of -58° to 86°, the specific bandwidth Δf is 1.1% fr or more. In order to be consistent with the exploration in other FEM simulations, the center point CP of the LN cutting angle is set to 36°. Fig.29B As shown, it can be seen that the center point CP of the LN cut angle is located near the maximum point on the fitting curve of the plot of the specific bandwidth Δf.

[0247] (LN propagation angle)

[0248] Fig. 30A This is a table showing FEM simulation conditions related to the LN propagation angle in Study Example 7. Fig. 30B 1 is a diagram showing the results of FEM simulation of the relationship between the LN propagation angle and the specific bandwidth Δf in Investigation Example 7. Fig. 30C This is a diagram showing the FEM simulation results of the relationship between the LN propagation angle and the sound velocity V in Study Example 7. In the FEM simulation related to the LN propagation angle in Study Example 7, the Pt electrode thickness was fixed to 12%λ, which is the center point CP in the above FEM simulation results. In addition, the LN thickness was fixed to 32.5%λ, which is the center point CP in the above FEM simulation results, and the LN cutting angle was fixed to 36°.

[0249] like Figures 30A to 30C As shown, it can be seen that in the range of the LN propagation angle being greater than 0° and less than 64° and greater than 116° and less than 180°, in other words, in the range of the LN propagation angle being greater than -64° and less than 64°, the specific bandwidth Δf is greater than 1.1% fr. Fig. 30B In the fitting curve of the plot of the specific bandwidth Δf shown, 0° and 180° of the LN propagation angle are equivalent, so there is actually a peak that is convex upward. The part of the maximum point of the fitting curve is selected as the center point CP. That is, the center point CP of the LN propagation angle is set to 0°.

[0250] <Configuration Example 7>

[0251] In elastic wave device 100 in configuration example 7 of the present embodiment based on the above-mentioned FEM simulation results, the main component of the constituent material of piezoelectric layer 2 is lithium niobate, and the thickness is 7.5%λ or more and 82.5%λ. In addition, the Euler angle of piezoelectric layer 2 is ( θ,ψ), is -5° to 5°, θ is -58° to 86°, and ψ is -64° to 64°. The main component of the material constituting the IDT electrode 3 is Pt, and the thickness is 0.05%λ to 100.0%λ.

[0252] In the elastic wave device 100 in the configuration example 7 of the present embodiment, the piezoelectric layer 2 may be the same as that in the configuration example 5 described above. In addition, the IDT electrode 3 may be composed of Pt, or may be substantially composed of Pt. The IDT electrode 3 may contain 70% by mass or more of Pt, or may contain 80% by mass or more of Pt. The remainder of the constituent material of the IDT electrode 3 other than Pt may be composed of any additive component and unavoidable impurities.

[0253] <Exploration Example 8: LN Film and Metal Electrode>

[0254] In the above-mentioned research examples 5 to 7, the electrode materials were set to Al, Cu, and Pt, respectively, and the piezoelectric layer 2 was set to an LN film. In contrast, in research example 8, based on the results of the above-mentioned research examples 5 to 7, the electrode material constituting the IDT electrode 3 was further studied when the piezoelectric layer 2 was set to an LN film.

[0255] Regarding the above discussion example 4, use Fig.17A as well as Fig. 17B The situations described above are also the same in this Research Example 8, and repeated descriptions are omitted.

[0256] In the above-mentioned Study Example 5, the center point CP of the Al electrode thickness is 24%λ, the sound velocity (elastic wave sound velocity) V at the center point CP is about 3100 m / s, and the specific bandwidth Δf at the center point CP is about 4.2 (refer to Figures 19A to 19C ). In addition, in the above-mentioned Study Example 6, the center point CP of the Cu electrode thickness is 18%λ, the sound velocity (elastic wave sound velocity) V at the center point CP is about 2600m / s, and the specific bandwidth Δf at the center point CP is about 5.3 (refer to Figures 23A to 23C ). In the above-mentioned study example 7, the center point CP of the Pt electrode thickness is 12%λ, the sound velocity (elastic wave sound velocity) V at the center point CP is about 2300m / s, and the specific bandwidth Δf at the center point CP is about 6.0 (refer to Figures 27A to 27C ).

[0257] Fig.31AThis is a diagram showing the relationship between the transverse wave velocity of the electrode material and the center point CP of the electrode thickness in the results of studying Examples 5 to 7. Fig.31B This is a graph showing the relationship between the transverse wave velocity and the sound velocity (elastic wave velocity) V of the electrode material in the results of studying Examples 5 to 7. Fig. 31C This is a graph showing the relationship between the transverse wave sound velocity and the specific bandwidth Δf of the electrode material in the results of studying Examples 5 to 7. Figures 31A to 31C The straight line and determination coefficient calculated by approximating the plots corresponding to the results of Study Examples 5 to 7 with a linear function are shown in FIG. Figures 31A to 31C As shown, it can be seen that the transverse wave sound velocity and sound velocity (elastic wave sound velocity) V of the electrode material and the specific bandwidth Δf have a linear function relationship with each other.

[0258] like Fig.31C As shown in the figure, it can be seen that when the transverse wave speed of the electrode material is below about 5000m / s, the specific bandwidth Δf is above 1.1%fr. Here, the sound speed of the conventional SAW is about 4000m / s. Conventional SAW includes Rayleigh waves and leaky waves. The sound speed of the leaky wave propagating through the LT film is about 4000m / s. Therefore, Fig.31B As shown, as the range of sound velocity (elastic wave sound velocity) V slower than the conventional SAW, the upper limit of the transverse wave sound velocity of the electrode material is set to 4005 m / s. Also, similar to the above-mentioned Study Example 4, the lower limit of the transverse wave sound velocity of the electrode material is set to 500 m / s.

[0259] <Configuration Example 8>

[0260] In the elastic wave device 100 in the structural example 8 of the present embodiment based on the FEM simulation results of the above-mentioned research examples 5 to 7 and the above-mentioned research results, the main component of the constituent material of the piezoelectric layer 2 is lithium niobate, and the thickness is not less than 7.5%λ and not more than 92.5%λ. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), The IDT electrode 3 is mainly composed of a metal having a transverse wave velocity of 500 m / s to 4005 m / s, and has a thickness of 0.05%λ to 100.0%λ.

[0261] In the elastic wave device 100 of another example of the configuration example 8 of the present embodiment based on the FEM simulation results of the above-mentioned discussion examples 5 to 7 and the above-mentioned discussion results, the main component of the constituent material of the piezoelectric layer 2 is lithium niobate, and the thickness is not less than 10.0%λ and not more than 82.5%λ. In addition, the Euler angle of the piezoelectric layer 2 is set to ( θ,ψ), The IDT electrode 3 is mainly composed of a metal having a transverse wave velocity of 500 m / s to 4005 m / s, and has a thickness of 0.05%λ to 100.0%λ.

[0262] In the elastic wave device 100 in Configuration Example 8 of the present embodiment or other examples thereof, the piezoelectric layer 2 may be the same as that in Configuration Example 5 described above. In addition, the IDT electrode 3 may be composed of a metal having a transverse wave sound velocity of 500 m / s or more and 4005 m / s or less (hereinafter referred to as "specific metal M2"), or may be substantially composed of the specific metal M2, and the main component of the constituent material may be the specific metal M2. The relationship between the constituent material of the IDT electrode 3 and the range of the transverse wave sound velocity is the same as that described in Configuration Example 4 described above, and therefore repeated description is omitted.

[0263] <Other structural examples>

[0264] Fig.32 1 is a perspective view showing another example of the structure of the elastic wave device 100 in the present embodiment. As described above, the elastic wave device 100 in the present embodiment only needs to be configured to excite the A0 mode Lamb wave, and the specific shape of the IDT electrode 3 is not particularly limited. Fig.32 As shown, elastic wave device 100 may include a transverse resonator 1 .

[0265] exist Fig.32 In the example shown, the resonator 1 may include a first IDT electrode 130 (IDT electrode on the input side) and a second IDT electrode 230 (IDT electrode on the output side) arranged in the x-direction. The first IDT electrode 130 may include two bus bars 131 (a first bus bar 131a and a second bus bar 131b) facing each other in the y-direction. In addition, the second IDT electrode 230 may include two bus bars 231 (a first bus bar 231a and a second bus bar 231b) facing each other in the y-direction.

[0266] For example, the input terminal Tin may be connected to the first bus bar 131a in the first IDT electrode 130, and the output terminal Tout may be connected to the second bus bar 231b in the second IDT electrode 230. The second bus bar 131b in the first IDT electrode 130 and the first bus bar 231a in the second IDT electrode 230 may be connected to ground terminals, respectively.

[0267] exist Fig.32In the example shown, the elastic wave device 100 may include a third electrode 14 on the propagation path between the first IDT electrode 130 and the second IDT electrode 230. The third electrode 14 may be, for example, an aluminum electrode film, and has a function of improving the transmission efficiency of the signal (A0 mode Lamb wave) from the first IDT electrode 130 to the second IDT electrode 230. The third electrode 14 may be connected to a ground terminal or may not be connected to a ground terminal. In the elastic wave device 100, the third electrode 14 may not be provided.

[0268] The elastic wave device 100 only needs to have the same shape and component ratio as the above-described IDT electrode 3 for the first IDT electrode 130 and the second IDT electrode 230. A known structure can be employed as the third electrode 14 .

[0269] <Other components 1>

[0270] Fig.33 FIG. 2 is a cross-sectional view showing another configuration example of the elastic wave device 100 according to the present embodiment. Fig.33 In the example shown, resonator 1 of elastic wave device 100 may include an acoustic reflection film between support substrate 5 and piezoelectric layer 2. The specific structure of the acoustic reflection film is not particularly limited. For example, elastic wave device 100 may include a reflective multilayer film 60 between support substrate 5 and piezoelectric layer 2.

[0271] The reflective multilayer film 60 may include a first layer 61 and a second layer 62 alternately stacked. The constituent material of the first layer 61 may be a material having a lower acoustic impedance than the constituent material of the second layer 62. For example, the main component of the constituent material of the first layer 61 may be silicon dioxide (SiO2). For example, the main component of the constituent material of the second layer 62 may be hafnium oxide (HfO2). In addition, the main component of the constituent material of the second layer 62 may also be any one of tantalum pentoxide (Ta2O5), zirconium dioxide (ZrO2), titanium oxide (TiO2) and magnesium oxide (MgO). The reflective multilayer film 60 may include at least one first layer 61 and at least one second layer 62. The layer in the reflective multilayer film 60 that is in contact with the piezoelectric layer 2 is the first layer 61. On the other hand, the layer closest to the supporting substrate 5 in the reflective multilayer film 60 may be any one of the first layer 61 and the second layer 62. For example, the reflective multilayer film 60 may include: a first layer 61 and a second layer 62 with a total of more than 3 layers and less than 12 layers.

[0272] <Other components 2>

[0273] Fig.34 FIG. 2 is a cross-sectional view showing another modified example of the elastic wave device 100 according to the present embodiment. Fig.34In the illustrated example, in the resonator 1 included in the elastic wave device 100 , at least a portion of the IDT electrode 3 may be buried in the piezoelectric layer 2 .

[0274] exist Fig.34 In the example shown, the upper surface of the electrode finger 32 is aligned with the upper surface of the piezoelectric layer 2 (is in the same plane), but the present invention is not limited to this. For example, the IDT electrode 3 may be buried in the piezoelectric layer 2 in such a manner that the upper surface of the electrode finger 32 is protruding or recessed relative to the upper surface of the piezoelectric layer 2. In this way, the stray light can be effectively reduced.

[0275] <Other components 3>

[0276] The resonant frequency of the elastic wave device 100 can be, for example, not less than 700 MHz and not more than 900 MHz. Here, when the cross-sectional thickness (expressed as %λ) of the piezoelectric layer 2 and the IDT electrode 3 is constant, the acoustic velocity V of the A0 mode Lamb wave is also constant. In this case, the resonant frequency can be adjusted by changing λ (in other words, the electrode finger pitch p) according to V=fλ (V: constant). In other words, λ is set to achieve the desired resonant frequency, and the cross-sectional thickness (expressed as %λ) of the piezoelectric layer 2 and the IDT electrode 3 is calculated based on the set λ. A resonator 1 having a piezoelectric layer 2 and an IDT electrode 3 of the calculated thickness can be manufactured.

[0277] <Communication device>

[0278] Fig.35 1 is a diagram showing a schematic structure of a communication device 151. The communication device 151 is an application example of the elastic wave device 100 of one aspect of the present disclosure, and performs wireless communication using radio waves. The communication device 151 may include: a splitter 101 as a transmission filter 109 and another splitter 101 as a reception filter 111. The two splitters 101 may each include the elastic wave device 100 of one aspect of the present disclosure. In this way, the communication device 151 may include the elastic wave device 100 of one aspect of the present disclosure.

[0279] In the communication device 151, the transmission information signal TIS including the information to be transmitted can be modulated and up-converted (converted into a high-frequency signal with a carrier frequency) by the RF-IC (Radio Frequency Integrated Circuit) 153 and converted into a transmission signal TS. The bandpass filter 155 can remove unnecessary components outside the passband for transmission from the TS. Then, the TS after removing the unnecessary components can be amplified by the amplifier 157 and input to the transmission filter 109.

[0280] The transmission filter 109 can remove unnecessary components outside the transmission passband from the input transmission signal TS. The transmission filter 109 can output the TS after removing the unnecessary components to the antenna 159 via the antenna terminal. The antenna 159 can convert the electrical signal TS input to itself into an electric wave as a wireless signal, and transmit the electric wave to the outside of the communication device 151.

[0281] In addition, the antenna 159 can convert the received radio waves from the outside into an electric signal, i.e., a received signal RS, and input the RS to the receiving filter 111 via the antenna terminal. The receiving filter 111 can remove unnecessary components outside the passband for reception from the input RS. The receiving filter 111 can output the received signal RS after removing the unnecessary components to the amplifier 161. The output RS can be amplified by the amplifier 161. The bandpass filter 163 can remove unnecessary components outside the passband for reception from the amplified RS. The RS after removing the unnecessary components is down-converted and demodulated by the RF-IC 153 and converted into a received information signal RIS.

[0282] TIS and RIS may be low frequency signals (baseband signals) including appropriate information. For example, TIS and RIS may be analog audio signals, or may be digitized audio signals. The passband of the wireless signal may be appropriately set and may comply with various well-known standards.

[0283] [Additional Notes]

[0284] The invention of the present disclosure is described above based on the drawings and embodiments. However, the invention of the present disclosure is not limited to the above-mentioned embodiments and embodiments. That is, the invention of the present disclosure can be variously modified within the scope shown in the present disclosure, and the embodiments obtained by appropriately combining the technical means respectively disclosed in different embodiments and embodiments are also included in the technical scope of the invention of the present disclosure. In other words, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. In addition, it should be noted that these deformations or modifications are also included in the scope of the present disclosure.

[0285] Description of Reference Numerals

[0286] 1 Oscillator

[0287] 2 Piezoelectric layer

[0288] 3 IDT electrode

[0289] 31 Busbar

[0290] 32 electrode fingers

[0291] 4 Reflector

[0292] 5 Support base plate

[0293] 6 Middle Layer

[0294] 100 Elastic wave device.

Claims

1. An elastic wave device having: support base plate; a piezoelectric layer, directly or indirectly in contact with the support substrate; and An IDT electrode is located on the piezoelectric layer; The elastic wave device excites an asymmetric 0th-order mode Lamb wave.

2. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is defined as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium tantalate. The thickness is 20.0%λ or more and 87.5%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to 8° and less than or equal to 74°, and ψ is greater than or equal to -26° and less than or equal to 26°; The IDT electrode: The main component of the material is Al. The thickness is 0.6%λ or more and 50.0%λ or less.

3. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium tantalate. The thickness is 17.5%λ or more and 90.0%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -20° and less than or equal to 80°, and ψ is greater than or equal to -40° and less than or equal to 40°; The IDT electrode: The main component of the material is Cu. The thickness is 0.2%λ or more and 58.0%λ or less.

4. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium tantalate. The thickness is 15.0%λ or more and 85.0%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -40° and less than or equal to 86°, and ψ is greater than or equal to -50° and less than or equal to 50°; The IDT electrode: The main component of the material is Pt. The thickness is 0.3%λ or more and 74.0%λ or less.

5. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium tantalate. The thickness is 15.0%λ or more and 90.0%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -40° and less than or equal to 86°, and ψ is greater than or equal to -50° and less than or equal to 50°; The IDT electrode: The main component of the constituent material is a metal having a transverse wave sound velocity of 500 m / s or more and 3473 m / s or less, The thickness is 0.2%λ or more and 74.0%λ or less.

6. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium tantalate. The thickness is 20.0%λ or more and 85.0%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to 8° and less than or equal to 74°, and ψ is greater than or equal to -26° and less than or equal to 26°; The IDT electrode: The main component of the constituent material is a metal having a transverse wave sound velocity of 500 m / s or more and 3473 m / s or less, The thickness is 0.6%λ or more and 50.0%λ or less.

7. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium niobate. The thickness is 10.0%λ or more and 92.5%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -38° and less than or equal to 90°, and ψ is greater than or equal to -50° and less than or equal to 50°; The IDT electrode: The main component of the material is Al. The thickness is 0.05%λ or more and 100.0%λ or less.

8. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium niobate. The thickness is 7.5%λ or more and 85.0%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -52° and less than or equal to 84°, and ψ is greater than or equal to -58° and less than or equal to 58°; The IDT electrode: The main component of the material is Cu. The thickness is 0.05%λ or more and 100.0%λ or less.

9. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium niobate. The thickness is 7.5%λ or more and 82.5%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -58° and less than or equal to 86°, and ψ is greater than or equal to -64° and less than or equal to 64°; The IDT electrode: The main component of the material is Pt. The thickness is 0.05%λ or more and 100.0%λ or less.

10. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium niobate. The thickness is 7.5%λ or more and 92.5%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -58° and less than or equal to 90°, and ψ is greater than or equal to -64° and less than or equal to 64°; The IDT electrode: The main component of the constituent material is a metal having a transverse wave sound velocity of 500 m / s or more and 4005 m / s or less, The thickness is 0.05%λ or more and 100.0%λ or less.

11. The elastic wave device according to claim 1, wherein a length twice the pitch of the plurality of electrode fingers included in the IDT electrode is set as a wavelength λ of the asymmetric 0th-order mode Lamb wave, The piezoelectric layer: The main component of the material is lithium niobate. The thickness is 10.0%λ or more and 82.5%λ or less, Assume that the Euler angles are (φ, θ, ψ), φ is greater than or equal to -5° and less than or equal to 5°, θ is greater than or equal to -38° and less than or equal to 84°, and ψ is greater than or equal to -50° and less than or equal to 50°; The IDT electrode, The main component of the constituent material is a metal having a transverse wave sound velocity of 500 m / s or more and 4005 m / s or less, The thickness is 0.05%λ or more and 100.0%λ or less. 12 . The elastic wave device according to claim 1 , further comprising an intermediate layer between the supporting substrate and the piezoelectric layer. 13 . The elastic wave device according to claim 1 , further comprising an acoustic reflection film between the support substrate and the piezoelectric layer. 14 . The elastic wave device according to claim 1 , wherein the specific bandwidth is 1.1% or more. 15 . The elastic wave device according to claim 1 , wherein at least a portion of the IDT electrode is buried in the piezoelectric layer.

16. A communication device comprising: the elastic wave device according to any one of claims 1 to 15.

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