Acoustic wave element

Abstract

[Problem] To provide an acoustic wave element capable of exciting a higher frequency plate wave by using a crystal substrate. [Solution] A piezoelectric substrate 11 is made of crystal. An electrode 12 is provided on at least one surface in a prescribed region of the piezoelectric substrate 11. A support substrate 13 supports the piezoelectric substrate 11 on the other surface in a region other than the prescribed region of the piezoelectric substrate such that the other surface in the prescribed region of the piezoelectric substrate 11 is in contact with a space. In the prescribed region of the piezoelectric substrate 11, a high-order mode and / or an overtone of a plate wave is excited. The sound velocity of the excited high-order mode and / or the excited overtone is greater than 10,000 m / s, and the electromechanical coupling coefficient is 0.1% or more.

Description

Acoustic Wave Devices

[0001] The present invention relates to an acoustic wave device.

[0002] In recent years, the global spread of the Internet and mobile communications has led to a significant increase in the amount of data sent and received over communication lines and the Internet. In particular, mobile communications, such as those for smartphones and tablet devices, are using higher frequencies to achieve higher speeds and larger capacities, which in turn requires higher reference frequencies at base stations. Meanwhile, increasing the speed and capacity of optical communications in data centers and backbone networks requires increasing the speed and capacity of the optical transceivers used there, which in turn requires high-frequency oscillators. Furthermore, atomic clocks require high-frequency oscillators of 3.4, 4.6 GHz, and other frequencies.

[0003] Crystal oscillators are used in network communications and related fields to provide heartbeat signals for processor clocks, bit timing for data links, sampling times for data conversion, master frequencies for tuners and synthesizers, etc. These crystal oscillators are required to be stable over temperature as reference oscillators, so acoustic wave elements such as bulk acoustic wave resonators (BAWR) and surface acoustic wave resonators (SAWR) using AT-cut quartz crystal substrates are generally used.

[0004] Conventionally, high-frequency oscillators have been made by multiplying the fundamental frequency of a typical BAWR or SAWR in a circuit, but multiplication generates noise, etc., which limits how high the frequency can be increased. Therefore, in order to suppress the generation of noise, etc., it is thought that an acoustic wave element that can be used without multiplication is needed.

[0005] In elastic wave devices using bulk acoustic waves (BAW), the frequency is determined by the ratio of the sound velocity in the substrate to twice the substrate thickness. Due to limitations in thinning the quartz substrate, limitations in microfabrication of electrodes, and the precision of stable thickness, the upper limit for practical BAWR is 54 MHz (see, for example, Non-Patent Document 1), making it difficult to achieve higher frequencies.

[0006] In devices (resonators, filters) that use surface acoustic waves (SAW), the surface acoustic waves are excited by interdigital transducers (IDTs) formed on the substrate, and their center frequency is determined by [sound velocity in the substrate / IDT period λ]. From this equation, we can see that there are two ways to increase the frequency of SAW devices: using a substrate with a faster sound velocity, or shortening the wavelength of the IDT.

[0007] Among quartz substrates, there is a moderate electromechanical coupling coefficient k for Rayleigh waves. 2 (k 2 The ST-cut quartz substrate is known as a substrate with a stable temperature characteristic and a sound velocity of 3,158 m / s, an electromechanical coupling coefficient k 2 is 0.16% (see, for example, Non-Patent Document 2), and the upper frequency limit of a quartz SAW resonator is 2 GHz (see, for example, Non-Patent Document 3). In addition to the ST cut, LST cut quartz substrates also exist (see, for example, Non-Patent Document 2), but they are rarely used because they contain a small amount of leakage.

[0008] For quartz substrates, we investigated the azimuth angle (cut angle) with good temperature characteristics using Lamb waves, which are one of the plate waves, and found that the electromechanical coupling coefficient k for Rayleigh waves is 0.1% or more, which is comparable to that of ST-cut quartz substrates. 2 It has been reported that there are two types of azimuth angles with an acoustic velocity of greater than 10,000 m / s, and that the acoustic velocity in the substrate is 10,000 m / s or less (see, for example, Non-Patent Documents 4 or 5). It has also been reported that there are two types of azimuth angles with an acoustic velocity of greater than 10,000 m / s, and that the electromechanical coupling coefficient is 0.1% or less (see, for example, Non-Patent Documents 4 or 5). However, there have been no reports to date of quartz crystal azimuth angles with an acoustic velocity greater than 10,000 m / s and an electromechanical coupling coefficient of 0.1% or more.

[0009] Teruhisa Miyazawa, "Crystal Device Basics Course No. 4: How is the Oscillation Frequency of a Quartz Crystal Determined?" [online], April 16, 2011, EE Times Japan, [Retrieved May 11, 2023], Internet: https: / / eetimes.itmedia.co.jp / ee / articles / 1104 / 05 / news111.html. C.S. Lam and D.E. Hol, "A Comparison of Temperature Performance of Saw Rafters Made on Short- and Long-Cut Quartz," Proc. IEEE Ultrason. Symp., 1988, p. 274. Seiko Epson Corporation, Technical Notes "Methods for Obtaining High-Frequency Output (Part 2: SAW Oscillators)," [online], [Retrieved June 20, 2023], Internet: https: / / www5.epsondevice.com / ja / information / technical_info / pdf / tech_notes2013_06saw.pdf; Yasuhiko Nakagawa and three others, "Temperature Characteristics of Substrates for Lamb-Wave-Type Elastic Wave Devices," Transactions of the Institute of Electronics, Information and Communication Engineers, Vol. J89-C, 2006, pp. 34-39; Hitoshi Yoshida and two others, "Propagation Characteristics of Substrates for Lamb-Wave-Type Elastic Wave Devices," Piezoelectric Materials and Devices Symposium 2008, 2008, pp. 89-90.

[0010] To increase the frequency of SAW devices that use quartz substrates, it is sufficient to use quartz substrates with a high acoustic velocity, but as described in Non-Patent Document 2, an ST-cut quartz substrate with a coupling coefficient of 0.1% or more and stable temperature characteristics has an acoustic velocity of 3,158 m / s for Rayleigh waves, which poses a problem that it is difficult to realize SAW devices that exceed 2 GHz, as described in Non-Patent Document 3. Furthermore, as described in Non-Patent Documents 4 and 5, when using Lamb waves, there is also the problem that no quartz substrate with an electromechanical coupling coefficient of 0.1% or more and an acoustic velocity of greater than 10,000 m / s has been found.

[0011] Incidentally, there have been no reports on SH-type plate waves up to now. In addition, Non-Patent Document 4 states that when Lamb waves are used, the sound velocity is small but the maximum coupling coefficient k 2 However, in order to further broaden the bandwidth of SAW devices, a quartz substrate with an even larger electromechanical coupling coefficient, for example, an electromechanical coupling coefficient of 0.5% or more, is required.

[0012] The present invention has been made in view of the above-mentioned problems, and has an object to provide an elastic wave element that uses a quartz substrate and is capable of exciting plate waves at higher frequencies.

[0013] In order to achieve the above object, the present invention provides an elastic wave device comprising: a piezoelectric substrate made of quartz; an electrode provided on at least one surface within a predetermined range of the piezoelectric substrate; and a support substrate supporting the piezoelectric substrate on the other surface outside the predetermined range so that the other surface within the predetermined range of the piezoelectric substrate is in contact with space, wherein the elastic wave device excites a higher-order mode and / or an overtone of a plate wave within the predetermined range of the piezoelectric substrate, the sound velocity of the excited higher-order mode and / or the overtone is greater than 10,000 m / s, and the electromechanical coupling coefficient is 0.1% or greater.

[0014] In the acoustic wave device according to the present invention, a piezoelectric substrate (hereinafter also referred to as a "quartz substrate") made of quartz crystal has a predetermined area on the other surface thereof in contact with a space, so that it can excite not only the fundamental mode of a plate wave but also its higher-order modes and overtones. Here, as shown in FIG. 1 , plate waves propagating through a thin plate include Lamb waves, which are composed of a longitudinal wave component and a shear vertical (SV) component of a transverse wave, and SH-type plate waves, which are composed of a shear horizontal (SH) component of a transverse wave. Furthermore, Lamb waves include antisymmetric modes (A-mode) and symmetric modes (S-mode). These plate wave components include the fundamental mode (A0, S0, SH0), their higher-order modes (A1, A2, ..., S1, S2, ..., SH1, SH2, ...), and overtones of the fundamental mode (A0-2, ..., S0-2, ..., SH0-2, ...).

[0015] The elastic wave element according to the present invention can excite higher modes and overtones of plate waves with sound velocities greater than 10,000 m / s, thereby making these components high frequency. Thus, the elastic wave element according to the present invention can excite plate waves of higher frequencies using a quartz substrate, making it possible to realize, for example, a high-frequency resonator. Furthermore, the elastic wave element according to the present invention has an electromechanical coupling coefficient k 2 The energy conversion efficiency is high, with a value of 0.1% or more. The support substrate is preferably made of a dielectric substrate such as a silicon substrate, a glass substrate, or a ceramic substrate.

[0016] In the acoustic wave element according to the present invention, the electrode may be an interdigital transducer having a wavelength λ, where λ is the wavelength of the plate wave, and may be provided on one surface of the piezoelectric substrate. In this case, plate waves with a frequency f (= acoustic velocity V / wavelength λ) can be excited. The electrode may be a plurality of electrodes, each provided on one surface of the piezoelectric substrate, or on one surface and the other surface of the piezoelectric substrate. When an interdigital transducer is provided on one surface of the piezoelectric substrate, the other surface may have a non-interdigital transducer with an area equal to or greater than that of the interdigital transducer. Furthermore, when the width of the electrode fingers is F and the gap between the electrode fingers is G, the metallization ratio MR (= F / (F+G)) of the interdigital transducer is not limited to 0.5 and is preferably in the range of 0.1 to 0.9. In these cases, higher modes and overtones of plate waves can also be excited.

[0017] In the acoustic wave device according to the present invention, in order to excite a higher order mode and / or overtone having a sound velocity of more than 10,000 m / s and to set the electromechanical coupling coefficient to 0.1% or more, the piezoelectric substrate preferably has a thickness normalized to the wavelength λ of the plate wave of 0.32λ or less. More specifically, for example, the piezoelectric substrate has an Euler angle of (0°±5°, 26° to 78° or 97° to 173°, 0°±5°), a thickness of 0.25λ or less, and excites a higher order mode and / or overtone of the SH type plate wave. １The piezoelectric substrate may be configured to excite a S mode, which is a higher-order mode of a symmetric mode of Lamb waves, and has an Euler angle of (0°±5°, 26° to 48°, or 60° to 153°, 0°±5°), a thickness of 0.25λ or less. １ The piezoelectric substrate may be configured to excite a high-order mode of the antisymmetric Lamb wave, which is an A mode, and has an Euler angle of (0°±5°, 85° to 105°, 0°±5°), a thickness of 0.12λ or less, and １ The piezoelectric substrate may have an Euler angle of (0°±5°, 5° to 142°, 90°±5°), a thickness of 0.29λ or less, and may be configured to excite a higher-order mode of an SH plate wave. １ The piezoelectric substrate may have an Euler angle of 90°±5°, 90°±5°, 0° to 70°, or 110° to 180°, a thickness of 0.28λ or less, and may be configured to excite a higher-order mode of an SH plate wave. １ The piezoelectric substrate may be configured to excite a high-order mode of the antisymmetric Lamb wave, which is an A mode, having an Euler angle of 90°±5°, 90°±5°, 0° to 65°, or 120° to 180°, a thickness of 0.27λ or less, and １ The piezoelectric substrate may have an Euler angle of 90°±5°, 90°±5°, 0° to 20°, or 152° to 180°, a thickness of 0.15λ or less, and may be configured to excite a symmetric mode S of a Lamb wave. ０ The overtone of S ０ The -2 mode may be excitable.

[0018] In addition, in the acoustic wave device according to the present invention, it is preferable that the acoustic velocity of the excited higher-order mode and / or the overtone is 10,500 m / s or more, and the electromechanical coupling coefficient is 0.15% or more. In this case, it is preferable that the thickness of the piezoelectric substrate is 0.29λ or less. More specifically, for example, the piezoelectric substrate has an Euler angle of (0°±5°, 30° to 75°, or 105° to 163°, 0°±5°), a thickness of 0.25λ or less, and an SH １The piezoelectric substrate may be configured to be capable of exciting a mode. The piezoelectric substrate has an Euler angle of (0°±5°, 30° to 45°, or 63° to 130°, 0°±5°), a thickness of 0.2λ or less, and an S １ The piezoelectric substrate may be configured to be able to excite a mode. The piezoelectric substrate has Euler angles of (0°±5°, 85° to 105°, 0°±5°), a thickness of 0.04λ or less, and an A １ The piezoelectric substrate may be configured to be capable of exciting an SH mode. １ The piezoelectric substrate may be configured to be capable of exciting an SH mode. １ The piezoelectric substrate may be configured to be able to excite a mode. The piezoelectric substrate has an Euler angle of 90°±5°, 90°±5°, 0° to 64°, or 129° to 180°, a thickness of 0.27λ or less, and an A １ The piezoelectric substrate may be configured to be capable of exciting a mode. The piezoelectric substrate may have an Euler angle of 90°±5°, 90°±5°, 0° to 6°, or 155° to 180°, a thickness of 0.13λ or less, and an S ０ The -2 mode may be excitable.

[0019] Furthermore, in the acoustic wave device according to the present invention, it is preferable that the acoustic velocity of the excited higher-order mode and / or the overtone is 10,500 m / s or more, and the electromechanical coupling coefficient is 0.2% or more. In this case, it is preferable that the thickness of the piezoelectric substrate is 0.25λ or less. More specifically, for example, the piezoelectric substrate has Euler angles of (0°±5°, 33° to 73°, or 113° to 148°, 0°±5°), a thickness of 0.25λ or less, and an SH １ The piezoelectric substrate may be configured to be capable of exciting a mode. The piezoelectric substrate has an Euler angle of (0°±5°, 35° to 43° or 65° to 120°, 0°±5°), a thickness of 0.18λ or less, and an S １The piezoelectric substrate may be configured to be capable of exciting an SH mode. １ The piezoelectric substrate may be configured to be capable of exciting an SH mode. １ The piezoelectric substrate may be configured to be able to excite a mode. The piezoelectric substrate has an Euler angle of 90°±5°, 90°±5°, 0° to 62°, or 138° to 180°, a thickness of 0.24λ or less, and an A １ The piezoelectric substrate may be configured to be capable of exciting a mode. The piezoelectric substrate may have an Euler angle of 90°±5°, 90°±5°, 0° to 6°, or 160° to 170°, a thickness of 0.09λ or less, and an S ０ The -2 mode may be excitable.

[0020] In addition, the acoustic wave device according to the present invention preferably has an electromechanical coupling coefficient of 0.5% or more, which is three times or more the electromechanical coupling coefficient of an ST-cut quartz substrate, so that it has a bandwidth three times or more wider than that of an acoustic wave device using an ST-cut quartz substrate. In this case, not only higher modes or overtones of plate waves but also the fundamental mode may be utilized. Specifically, for example, the piezoelectric substrate has Euler angles of (0°±5°, 52° to 65°, 0°±5°), a thickness of 0.1λ or less, and an SH １ The piezoelectric substrate may be configured to be capable of exciting a mode. The piezoelectric substrate has Euler angles of (0°±5°, 75° to 102°, 0°±5°), a thickness of 0.12λ or less, and an S １ The piezoelectric substrate may be configured to be able to excite a mode. ０ The piezoelectric substrate may be configured to be capable of exciting the -2 mode. ０ The piezoelectric substrate may be configured to be able to excite the SH mode. ０The piezoelectric substrate may be configured to be capable of exciting the SH mode. １ The piezoelectric substrate may be configured to be able to excite a mode. The piezoelectric substrate has an Euler angle of 90°±5°, 90°±5°, 0° to 35°, or 172° to 180°, a thickness of 0.15λ or less, and an A １ The mode may be excitable.

[0021] Here, the Euler angles (φ, θ, ψ) are in a right-handed system and represent the cross section of the piezoelectric substrate and the propagation direction of the elastic wave. Specifically, with respect to the X, Y, and Z crystal axes of the quartz crystal that constitutes the piezoelectric substrate, the X axis is rotated counterclockwise by φ around the Z axis as the rotation axis to obtain the X' axis. Next, the Z axis is rotated counterclockwise by θ around the X' axis to obtain the Z' axis. In this case, the Z' axis is the normal, and the plane containing the X' axis is the cross section of the piezoelectric substrate. The direction of counterclockwise rotation of the X' axis by ψ around the Z' axis is the propagation direction of the elastic wave. The axis perpendicular to the X' and Z' axes, obtained by moving the Y axis through these rotations, is defined as the Y' axis.

[0022] By defining the Euler angles in this way, for example, propagation in the X direction with a 40° rotated Y-plate is expressed as Euler angles (0°, −50°, 0°), and propagation in the X direction with a 40° rotated Y-plate is expressed as Euler angles (0°, −50°, 90°).

[0023] When cutting a piezoelectric substrate at a desired Euler angle, there is a possibility of an error of up to ±0.5° for each component of the Euler angle. Regarding elastic wave characteristics, a deviation of ±5° for φ and ψ, among the Euler angles (φ, θ, ψ), causes almost no difference in characteristics. Furthermore, the planes (0°, θ + 360°, 0°) are equivalent to the Euler angles (0°, θ, 0°). On the other hand, the planes (0°, θ + 180°, 0°) are not equivalent to the planes (0°, θ, 0°) in terms of crystallography, because they are the difference between the + and - planes, i.e., the front and back surfaces of the substrate. However, since acoustic wave devices exhibit the same frequency characteristics on both the front and back surfaces, the orientations of the front and back surfaces of the substrate are also considered equivalent in terms of acoustics.

[0024] According to the present invention, it is possible to provide an acoustic wave element that can excite plate waves at higher frequencies using a quartz substrate.

[0025] (a) A cross-sectional view showing a plate wave propagating through a thin plate, (b) A cross-sectional view showing the propagation of a Lamb wave and a perspective view showing the vibration direction of each mode of the Lamb wave, (c) A cross-sectional view showing the propagation of an SH wave and a perspective view showing the vibration direction of the fundamental mode of the SH wave, (d) A cross-sectional view showing an acoustic wave element according to an embodiment of the present invention, (a) A configuration having an interdigital transducer (IDT), (b) A configuration having an interdigital transducer and a cavity between a piezoelectric substrate and a support substrate, (c) A configuration having multiple electrodes, (d) A configuration having multiple electrodes on both sides of a piezoelectric substrate, (e) A configuration having an IDT on both sides of a piezoelectric substrate, (f) A cross-sectional view showing a configuration having an IDT and a full-surface electrode on each side of a piezoelectric substrate, and (g) A plan view of an interdigital transducer. A graph showing the Euler angle θ dependence of the acoustic velocity of various plate waves excited in an acoustic wave element using a 0.1λ-thick (0°, θ, 0°) quartz substrate according to an embodiment of the present invention. The electromechanical coupling factor k of various plate waves excited in the elastic wave element using a quartz substrate having a thickness of 0.1λ (0°, θ, 0°) according to the embodiment of the present invention is 2 5 is a graph showing the Euler angle θ dependence of the acoustic velocity (Phase Velocity) of the SH1 mode of the acoustic wave device using a (0°, 60°, 0°) quartz substrate, the SH1 mode of the acoustic wave device using a (0°, 130°, 0°) quartz substrate, the S1 mode of the acoustic wave device using a (0°, 80°, 0°) quartz substrate, and the A1 mode of the acoustic wave device using a (0°, 95°, 0°) quartz substrate, according to an embodiment of the present invention, on the thickness of the quartz substrate. 21 is a graph showing the dependence of the acoustic velocity (Velocity) of various plate waves excited in an elastic wave device using a quartz substrate having a thickness of 0.1λ (0°, θ, 90°) according to an embodiment of the present invention on the Euler angle θ. 2 is a graph showing the dependence of the electromechanical coupling factor k of various plate waves excited in an elastic wave device using a quartz substrate having a thickness of 0.1λ (0°, θ, 90°) according to an embodiment of the present invention. 2 9 is a graph showing the Euler angle θ dependence of the acoustic velocity (Phase Velocity) of the SH1 mode of the acoustic wave device using a quartz substrate (0°, 40°, 90°) and the SH1 mode of the acoustic wave device using a quartz substrate (0°, 120°, 90°) according to an embodiment of the present invention, on the thickness of the quartz substrate. 2 1 is a graph showing the dependence of the acoustic velocity (Velocity) of various plate waves excited in an elastic wave device using a (90°, 90°, ψ) quartz substrate having a thickness of 0.1λ on the Euler angle ψ of the quartz substrate; and 2 is a graph showing the dependence of the electromechanical coupling factor k of various plate waves excited in an elastic wave device using a (90°, 90°, ψ) quartz substrate having a thickness of 0.1λ on the Euler angle ψ of the quartz substrate. 2 13 is a graph showing the Euler angle ψ dependence of the acoustic velocity (Phase Velocity) of the SH1 mode, A1 mode, and S0-2 mode of an acoustic wave device using a (90°, 90°, 0°) quartz substrate according to an embodiment of the present invention, and the electromechanical coupling factor k of each mode of the acoustic wave device shown in FIG. 215 is a graph showing the dependence of the acoustic velocity (Phase Velocity) of the SH1 mode, A1 mode, and S0-2 mode of an acoustic wave device using a (90°, 90°, 160°) quartz substrate on the thickness of the quartz substrate according to an embodiment of the present invention. 2 10 is a graph showing the dependence of the thickness of the quartz substrate on the thickness of the quartz substrate.

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings and examples. Figures 2 to 16 show an acoustic wave element according to an embodiment of the present invention. As shown in Figure 2, acoustic wave element 10 has piezoelectric substrate 11, electrode 12, and support substrate 13.

[0027] As shown in FIGS. 2( a ) to 2 ( f ), the piezoelectric substrate 11 is made of quartz crystal and has a thin plate shape. The electrode 12 is provided on one surface or one and the other surfaces of a predetermined area of ​​the piezoelectric substrate 11. As shown in FIGS. 2( a ) and 2 ( b ), the electrode 12 may be, for example, an interdigital transducer (IDT) shown in FIG. 2( g ) and provided on one surface of the piezoelectric substrate 11. Alternatively, as shown in FIGS. 2( c ) and 2 ( d ), the electrode 12 may be composed of a plurality of electrodes and provided on one surface or one and the other surfaces of the piezoelectric substrate 11. Alternatively, as shown in FIG. 2( e ), the electrode 12 may be an IDT and provided on both surfaces of the piezoelectric substrate 11. Alternatively, as shown in FIG. 2( e ), the electrode 12 may be composed of an IDT provided on one surface of the piezoelectric substrate 11 and a full-surface electrode with an area approximately equal to or larger than the IDT and provided on the other surface. The IDTs in FIGS. 2(a), (b), (e), and (f) each represent one wavelength, and the electrodes in FIGS. 2(c) and (d) each represent a half wavelength.

[0028] The support substrate 13 is provided to support the piezoelectric substrate 11 at a portion of the other surface of the piezoelectric substrate 11 other than a predetermined area. For example, as shown in FIGS. 2( a), 2(c) to 2(f), the support substrate 13 may support the piezoelectric substrate 11 at the end or edge of the piezoelectric substrate 11, leaving a predetermined area of ​​the other surface of the piezoelectric substrate 11 open. Alternatively, as shown in FIG. 2(b), the support substrate 13 may form a cavity 14 in a portion of the other surface facing the predetermined area of ​​the piezoelectric substrate 11, and support the piezoelectric substrate 11 at the end or edge of the piezoelectric substrate 11. In this way, the support substrate 13 is configured so that the other surface of the predetermined area of ​​the piezoelectric substrate 11 is in contact with the space. The support substrate 13 is made of a dielectric substrate, such as a silicon substrate, a glass substrate, or a ceramic substrate.

[0029] Acoustic wave element 10 is capable of exciting plate waves by contacting the other surface of piezoelectric substrate 11 within a predetermined range with space. In acoustic wave element 10, where λ is the wavelength of the excited plate waves, the thickness of piezoelectric substrate 11 is 0.32λ or less. This allows acoustic wave element 10 to excite higher-order modes and / or overtones of plate waves with sound velocities greater than 10,000 m / s within a predetermined range of piezoelectric substrate 11. Furthermore, the electromechanical coupling coefficient due to these components is configured to be 0.1% or greater.

[0030] 2( g), when acoustic wave element 10 includes electrode 12 formed as an interdigital transducer (IDT), the electrode finger period (wavelength) is set to λ, thereby enabling excitation of plate waves having a center frequency fc (=V / λ) determined from the acoustic velocity V and wavelength λ of the vibration mode being used. When acoustic wave element 10 includes multiple electrodes 12, plate waves having frequencies determined for the wavelength λ of each electrode 12 can be excited.

[0031] Next, the operation will be described. In acoustic wave element 10, the other surface of a predetermined area of ​​piezoelectric substrate 11 made of quartz is in contact with space, and piezoelectric substrate 11 has a thickness of 0.32λ or less. Therefore, in addition to the fundamental mode of plate waves, higher modes and overtones with sound velocities greater than 10,000 m / s can be excited. This also makes it possible to make these higher mode and overtone components higher frequency. In this way, acoustic wave element 10 can excite higher frequency plate waves using quartz substrate 11, thereby realizing, for example, a high-frequency resonator. Furthermore, acoustic wave element 10 has an electromechanical coupling coefficient k 2 is 0.1% or more, and the energy conversion efficiency is good.

[0032] The following describes an example of acoustic wave element 10. In this example, acoustic wave element 10 has the configuration shown in Fig. 2(a), and electrode 12 is an interdigital transducer with a wavelength λ.

[0033] [When a (0°, θ, 0°) quartz substrate is used] When a (0°, θ, 0°) quartz substrate 11 having a thickness of 0.1λ is used, the acoustic velocity and electromechanical coupling coefficient k of various excited plate waves are 2 The dependence of the Euler angle θ on the sound velocity was calculated and is shown in Figures 3 and 4. As shown in Figure 3, in the SH1, S1, A1, SH2, and A2 modes, the sound velocity was confirmed to be 17,500 m / s or higher regardless of the angle θ. In addition, in the S0-2 mode, the sound velocity was confirmed to be 11,000 m / s or higher regardless of the angle θ. These sound velocities are three to six times the sound velocity of 3,158 m / s of Rayleigh waves in an ST-cut quartz substrate.

[0034] As shown in FIG. 4, in the SH1 mode, when θ is 26° to 78° and 97° to 173°, k 2 becomes 0.1% or more, and when θ = 30° to 75° and 105° to 163°, k 2 becomes 0.15% or more, and when θ = 33° to 73° and 113° to 148°, k 2 becomes 0.2% or more, and when θ is between 40° and 70°, k 2 It was confirmed that k was 0.3% or more. In addition, in the S1 mode, when θ was 26° to 48° and 60° to 153°, 2becomes 0.1% or more, and when θ = 30° to 45° and 63° to 130°, k 2 becomes 0.15% or more, and when θ = 35° to 43° and 65° to 120°, k 2 becomes 0.2% or more, and when θ is between 70° and 115°, k 2 becomes 0.3% or more, and when θ is between 75° and 102°, k 2 It was confirmed that this k 2 It is believed that a range in which the difference is 0.5% or more is effective for widening the bandwidth.

[0035] In addition, in A1 mode, θ = 85° to 105°, k 2 It was confirmed that k is 0.1% or more. In addition, in the S0-2 mode, k 2 becomes 0.45% or more, and when θ = 0° to 135° and 175° to 180°, k 2 It was confirmed that this k 2 The range where is 0.5% or more is considered to be effective for broadening the bandwidth. In particular, when θ is between 0° and 25°, the k 2 is 0.5% or more, while k for modes other than the S0-2 mode 2 Since the value is less than 0.05%, the spurious signals are small, and it can be said that this is an azimuth angle that is particularly effective for broadbanding in the S0-2 mode. Also, in the S0 mode, k 2 It was confirmed that the coefficient of the gain was 0.6% or more, which is considered to be effective for broadening the bandwidth.

[0036] From the results of FIGS. 3 and 4, when a quartz crystal substrate 11 having a high sound velocity (10,000 m / s or more) and a large electromechanical coupling coefficient (0.1% or more) is used, the sound velocity of the excited plate wave and the electromechanical coupling coefficient k 2The thickness dependence of the quartz substrate 11 was determined and is shown in Figures 5 and 6. In the SH1 mode, a (0°, 60°, 0°) quartz substrate 11 was used to represent the (0°, 26° to 78°, 0°) quartz substrate 11, and a (0°, 130°, 0°) quartz substrate 11 was used to represent the (0°, 97° to 173°, 0°) quartz substrate 11. In the S1 mode, a (0°, 80°, 0°) quartz substrate 11 was used to represent the (0°, 60° to 153°, 0°) quartz substrate 11. In the A1 mode, a (0°, 95°, 0°) quartz substrate 11 was used to represent the (0°, 85° to 105°, 0°) quartz substrate 11.

[0037] As shown in Figure 5, in the SH1 mode of the (0°, 60°, 0°) quartz substrate 11, it was confirmed that when the thickness of the quartz substrate 11 is 0.02λ to 0.35λ, the sound velocity is 7,000 m / s or more, when the thickness is 0.02λ to 0.3λ, the sound velocity is 8,500 m / s or more, when the thickness is 0.02λ to 0.25λ, the sound velocity is 10,500 m / s or more, and when the thickness is 0.02λ to 0.23λ, the sound velocity is 11,000 m / s or more. Also, as shown in Figure 6, when the thickness of the quartz substrate 11 is 0.02λ to 0.35λ, the sound velocity is 12,000 m / s or more. 2 is 0.1% or more, the thickness is 0.02λ to 0.3λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.27λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.21λ, and k 2 is 0.3% or more, the thickness is 0.02λ to 0.1λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.25λ, the sound velocity is 10,500 m / s or more and the k value is 0.2% or more. 2 Also, k 2 It is believed that a range in which the difference is 0.5% or more is effective for widening the bandwidth.

[0038] As shown in Figure 5, in the SH1 mode of the (0°, 130°, 0°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.24λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.23λ. Also, as shown in Figure 6, when the thickness of the quartz substrate 11 was 0.02λ to 0.2λ, the sound velocity was 10,500 m / s or more when the thickness was 0.02λ to 0.23λ. 2 is 0.1% or more, the thickness is 0.02λ to 0.16λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.12λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.05λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.2λ, the sound velocity is 11,000 m / s or more and the k value is 0.1% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.16λ, a sound velocity of 11,000 m / s or more and a k value of 0.15% or more are obtained. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.12λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 It can be seen that

[0039] As shown in Figure 5, in the S1 mode of the (0°, 80°, 0°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.25λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.23λ. Also, as shown in Figure 6, when the thickness of the quartz substrate 11 was 0.02λ to 0.25λ, the sound velocity was 10,500 m / s or more when the thickness was 0.02λ to 0.23λ. 2 is 0.1% or more, the thickness is 0.02λ to 0.2λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.18λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.16λ, and k 2 is 0.3% or more, the thickness is 0.02λ to 0.12λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.25λ, the sound velocity is 10,500 m / s or more and the k value is 0.1% or more. 2When the thickness of the quartz crystal substrate 11 is between 0.02λ and 0.2λ, a sound velocity of 11,000 m / s or more and a k value of 0.15% or more are obtained. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.18λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 Also, k 2 It is believed that a range in which the difference is 0.5% or more is effective for widening the bandwidth.

[0040] As shown in Figure 5, in the A1 mode of the (0°, 95°, 0°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.2λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.18λ. Also, as shown in Figure 6, when the thickness of the quartz substrate 11 was 0.02λ to 0.12λ, the sound velocity was 10,500 m / s or more when the thickness was 0.02λ to 0.18λ. 2 is 0.1% or more, the thickness is 0.02λ to 0.04λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.12λ, the sound velocity is 11,000 m / s or more and the k value is 0.1% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.04λ, a sound velocity of 11,000 m / s or more and a k value of 0.15% or more are obtained. 2 It can be seen that

[0041] [When a (0°, θ, 90°) quartz substrate is used] When a (0°, θ, 90°) quartz substrate 11 having a thickness of 0.1λ is used, the acoustic velocity and electromechanical coupling coefficient k of various excited plate waves are 2 The dependence of the Euler angle θ on the sound velocity was calculated and is shown in Figures 7 and 8. As shown in Figure 7, in the SH1, S1, A1, SH2, and A2 modes, the sound velocity was confirmed to be 18,000 m / s or higher at any θ, i.e., at θ = 0° to 180°. In addition, in the S0-2 mode, the sound velocity was confirmed to be greater than 10,000 m / s at any θ.

[0042] Also, as shown in FIG. 8, in the SH1 mode, when θ is between 5° and 142°, k 2 becomes 0.1% or more, and when θ is between 10° and 140°, k 2becomes 0.15% or more, and when θ = 18° to 58° and 108° to 135°, k 2 becomes 0.2% or more, and when θ = 38° to 45°, k 2 It was confirmed that the k value of the SH1 mode was 0.3% or more. 2 is 0.15% or more, while k for modes other than SH1 mode 2 Since is very small, the spurious emissions are small, and it can be said that this is an effective azimuth angle for the SH1 mode.

[0043] As shown in Figure 7, it was confirmed that in the SH0 mode, which is the fundamental mode of the SH type plate wave, the sound velocity is less than 5,000 m / s regardless of the angle θ. Also, as shown in Figure 8, in the SH0 mode, the sound velocity is smaller than 5,000 m / s at θ = 0° to 45° and θ = 135° to 180°. 2 becomes 0.5% or more, and when θ = 0° to 28° and 145° to 180°, k 2 From these results, it can be said that although the sound velocity is small in the SH0 mode, the quartz crystal substrate 11 having these azimuth angles is effective for a wide-band resonator.

[0044] From the results of FIGS. 7 and 8, when a quartz crystal substrate 11 having a high sound velocity (10,000 m / s or more) and a large electromechanical coupling coefficient (0.2% or more) is used, the sound velocity of the excited plate wave and the electromechanical coupling coefficient k 2 The thickness dependence of the quartz substrate 11 was determined and is shown in Figures 9 and 10. The quartz substrate 11 (0°, 40°, 90°) was used to represent the quartz substrate 11 (0°, 18° to 58°, 90°) of the SH1 mode, and the quartz substrate 11 (0°, 120°, 90°) was used to represent the quartz substrate 11 (0°, 108° to 135°, 90°).

[0045] As shown in Figure 9, in the SH1 mode of the (0°, 40°, 90°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.29λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.27λ. Also, as shown in Figure 10, when the thickness of the quartz substrate 11 was 0.02λ to 1.0λ, the k 2is 0.1% or more, the thickness is 0.02λ to 0.38λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.25λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.18λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.29λ, the sound velocity is 10,500 m / s or more and the k value is 0.15% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.25λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 It can be seen that

[0046] As shown in Figure 9, in the SH1 mode of the quartz substrate 11 (0°, 120°, 90°), it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.21λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.19λ. Also, as shown in Figure 10, when the thickness of the quartz substrate 11 was 0.02λ to 1.0λ, the sound velocity was 10,500 m / s or more when the thickness was 0.02λ to 0.19λ. 2 is 0.1% or more, the thickness is 0.02λ to 0.43λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.28λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.18λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.21λ, the sound velocity is 10,500 m / s or more and the k value is 0.2% or more. 2 It can be seen that

[0047] [When a (90°, 90°, ψ) quartz substrate is used] When a (90°, 90°, ψ) quartz substrate 11 having a thickness of 0.1λ is used, the acoustic velocity and electromechanical coupling coefficient k of various excited plate waves are 2 The dependence of the Euler angle ψ on the sound velocity was calculated and is shown in Figures 11 and 12. As shown in Figure 11, it was confirmed that the sound velocity was 18,000 m / s or more in the SH1, S1, and A1 modes regardless of the ψ. It was also confirmed that the sound velocity was greater than 10,000 m / s in the S0-2 mode regardless of the ψ.

[0048] As shown in FIG. 12, in the SH1 mode, when ψ is 0° to 70° and 110° to 180°, k 2 becomes 0.1% or more, and when ψ = 0° to 57° and 113° to 180°, k 2 becomes 0.15% or more, and when ψ = 0° to 43° and 120° to 180°, k 2 becomes 0.2% or more, and when ψ = 0° to 27° and 127° to 180°, k 2 becomes 0.3% or more, and when ψ = 140° to 175°, k 2 It was confirmed that this k 2 It is believed that a range in which the difference is 0.5% or more is effective for widening the bandwidth.

[0049] In addition, in A1 mode, ψ = 0° to 65°, 120° to 180°, k 2 becomes 0.1% or more, and when ψ = 0° to 64° and 129° to 180°, k 2 is 0.15% or more, and when ψ = 0° to 62° and 138° to 180°, k 2 becomes 0.2% or more, and when ψ = 0° to 52° and 155° to 180°, k 2 becomes 0.3% or more, and when ψ = 0° to 35° and 172° to 180°, k 2 It was confirmed that this k 2 The range where is 0.5% or more is considered to be effective for widening the bandwidth. In addition, in the S0-2 mode, when ψ is 0° to 20° and 152° to 180°, k 2 becomes 0.1% or more, and when ψ = 0° to 6° and 155° to 180°, k 2 becomes 0.15% or more, and when ψ = 160° to 170°, k 2 was confirmed to be 0.2% or more.

[0050] From the results of FIGS. 11 and 12, when a quartz crystal substrate 11 having a high sound velocity (10,000 m / s or more) and a large electromechanical coupling coefficient (0.1% or more) is used, the sound velocity of the excited plate wave and the electromechanical coupling coefficient k 2 The thickness dependency of the quartz crystal substrate 11 was calculated and shown in Figs. 2As representatives of the quartz crystal substrate 11 in the ψ range where the value is 0.1% or more, the (90°, 90°, 0°) quartz crystal substrate 11 and the (90°, 90°, 160°) quartz crystal substrate 11 of the SH1, A1, and S0-2 modes were used.

[0051] As shown in Figure 13, in the SH1 mode of the (90°, 90°, 0° to 70°) quartz substrate 11, it was confirmed that when the thickness of the quartz substrate 11 is 0.02λ to 0.28λ, the sound velocity is 10,500 m / s or more, and when the thickness is 0.02λ to 0.26λ, the sound velocity is 11,000 m / s or more. Also, as shown in Figure 14, when the thickness of the quartz substrate 11 is 0.02λ to 0.28λ, the k 2 is 0.1% or more, the thickness is 0.02λ to 0.25λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.22λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.28λ, the sound velocity is 10,500 m / s or more and the k value is 0.1% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.25λ, a sound velocity of 11,000 m / s or more and a k value of 0.15% or more are obtained. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.22λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 It can be seen that

[0052] As shown in Figure 13, in the A1 mode of the (90°, 90°, 0°) quartz substrate 11, which is representative of the (90°, 90°, 0° to 65°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.27λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.25λ. Also, as shown in Figure 14, when the thickness of the quartz substrate 11 was 0.02λ to 0.33λ, the k 2 is 0.1% or more, the thickness is 0.02λ to 0.28λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.24λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.15λ, and k 2From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.27λ, the sound velocity is 10,500 m / s or more and the k value is 0.15% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.24λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 Also, k 2 It is believed that a range in which the difference is 0.5% or more is effective for widening the bandwidth.

[0053] As shown in Figure 13, in the S0-2 mode of the (90°, 90°, 0° to 20°) quartz substrate 11, it was confirmed that when the thickness of the quartz substrate 11 is 0.02λ to 0.15λ, the sound velocity is 10,500 m / s or more, and when it is 0.02λ to 0.14λ, the sound velocity is 11,000 m / s or more. Also, as shown in Figure 14, when the thickness of the quartz substrate 11 is 0.02λ to 0.22λ, the k 2 is 0.1% or more, the thickness is 0.02λ to 0.13λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.09λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.15λ, the sound velocity is 10,500 m / s or more and the k value is 0.1% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.13λ, a sound velocity of 11,000 m / s or more and a k value of 0.15% or more are obtained. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.09λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 It can be seen that

[0054] As shown in Figure 15, in the SH1 mode of the (90°, 90°, 160°) quartz substrate 11, which is representative of the (90°, 90°, 110° to 180°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.22λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.2λ. Also, as shown in Figure 16, when the thickness of the quartz substrate 11 was 0.02λ to 0.34λ, the k2 is 0.1% or more, the thickness is 0.02λ to 0.28λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.24λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.2λ, and k 2 is 0.3% or more, the thickness is 0.02λ to 0.16λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.22λ, the sound velocity is 10,500 m / s or more and the k value is 0.2% or more. 2 When the thickness of the quartz crystal substrate 11 is between 0.02λ and 0.2λ, a sound velocity of 11,000 m / s or more and a k value of 0.3% or more are obtained. 2 Also, k 2 It is believed that a range in which the difference is 0.5% or more is effective for widening the bandwidth.

[0055] As shown in Figure 15, in the A1 mode of the (90°, 90°, 160°) quartz substrate 11, which is representative of the (90°, 90°, 120° to 180°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.34λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.32λ. Also, as shown in Figure 16, when the thickness of the quartz substrate 11 was 0.02λ to 0.32λ, the k 2 is 0.1% or more, the thickness is 0.02λ to 0.26λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.22λ, and k 2 is 0.2% or more, the thickness is 0.02λ to 0.15λ, and k 2 is 0.3% or more, the thickness is 0.02λ to 0.08λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.32λ, the sound velocity is 11,000 m / s or more and the k value is 0.1% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.26λ, a sound velocity of 11,000 m / s or more and a k value of 0.15% or more are obtained. 2When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.22λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 Also, k 2 It is believed that a range in which the difference is 0.5% or more is effective for widening the bandwidth.

[0056] As shown in Figure 15, in the S0-2 mode of the (90°, 90°, 160°) quartz substrate 11, which is representative of the (90°, 90°, 152° to 180°) quartz substrate 11, it was confirmed that the sound velocity was 10,500 m / s or more when the thickness of the quartz substrate 11 was 0.02λ to 0.15λ, and the sound velocity was 11,000 m / s or more when the thickness was 0.02λ to 0.1λ. Also, as shown in Figure 16, when the thickness of the quartz substrate 11 was 0.02λ to 0.2λ, the k 2 is 0.1% or more, the thickness is 0.02λ to 0.13λ, and k 2 is 0.15% or more, the thickness is 0.02λ to 0.09λ, and k 2 From these results, it was confirmed that, for example, when the thickness of the quartz crystal substrate 11 is 0.02λ to 0.15λ, the sound velocity is 10,500 m / s or more and the k value is 0.1% or more. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.13λ, a sound velocity of 10,500 m / s or more and a k value of 0.15% or more are obtained. 2 When the thickness of the quartz crystal substrate 11 is 0.02λ to 0.09λ, a sound velocity of 11,000 m / s or more and a k value of 0.2% or more are obtained. 2 It can be seen that

[0057] 10 Acoustic wave element 11 Piezoelectric substrate (quartz substrate) 12 Electrode 13 Support substrate 14 Cavity

Claims

1. An elastic wave element comprising: a piezoelectric substrate made of quartz; an electrode provided on at least one surface within a predetermined range of the piezoelectric substrate; and a support substrate supporting the piezoelectric substrate on the other surface outside the predetermined range so that the other surface of the piezoelectric substrate within the predetermined range is in contact with space, wherein a higher-order mode and / or overtone of a plate wave is excited within the predetermined range of the piezoelectric substrate, the sound velocity of the excited higher-order mode and / or overtone is greater than 10,000 m / s, and the electromechanical coupling coefficient is 0.1% or greater.

2. The elastic wave element according to claim 1, wherein said electrode is an interdigital electrode having a wavelength of λ, said interdigital electrode being provided on said one surface of said piezoelectric substrate ...

3. The acoustic wave element according to claim 1, wherein the electrodes are made up of a plurality of electrodes, each of which is provided on the one surface of the piezoelectric substrate or on the one surface and the other surface of the piezoelectric substrate.

4. The elastic wave element according to any one of claims 1 to 3, wherein the piezoelectric substrate has a thickness of 0.32λ or less, where λ is the wavelength of the plate wave.

5. An elastic wave element according to any one of claims 1 to 3, characterized in that the sound velocity of the excited higher mode and / or overtone is 10,500 m / s or more, and the electromechanical coupling coefficient is 0.15% or more.

6. The piezoelectric substrate has an Euler angle of (0°±5°, 26° to 78° or 97° to 173°, 0°±5°), a thickness of 0.25λ or less, and is a high-order mode SH plate wave. １ The acoustic wave element according to claim 1 , wherein a mode is excited.

7. The piezoelectric substrate has an Euler angle of (0°±5°, 26° to 48° or 60° to 153°, 0°±5°), a thickness of 0.25λ or less, and a high-order mode of the symmetric mode of Lamb waves, S １ The acoustic wave element according to claim 1 , wherein a mode is excited.

8. The piezoelectric substrate has an Euler angle of (0°±5°, 85° to 105°, 0°±5°), a thickness of 0.12λ or less, and is a high-order mode of the antisymmetric mode of Lamb waves, A １ The acoustic wave element according to claim 1 , wherein a mode is excited.

9. The piezoelectric substrate has an Euler angle of (0°±5°, 5° to 142°, 90°±5°), a thickness of 0.29λ or less, and is a high-order mode SH plate wave. １ The acoustic wave element according to claim 1 , wherein a mode is excited.

10. The piezoelectric substrate has an Euler angle of (90°±5°, 90°±5°, 0° to 70°, or 110° to 180°), a thickness of 0.28λ or less, and is a high-order mode SH plate wave. １ The acoustic wave element according to claim 1 , wherein a mode is excited.

11. The piezoelectric substrate has an Euler angle of (90°±5°, 90°±5°, 0° to 65°, or 120° to 180°), a thickness of 0.32λ or less, and a high-order mode of the antisymmetric mode of Lamb waves, A １ The acoustic wave element according to claim 1 , wherein a mode is excited.

12. The piezoelectric substrate has an Euler angle of (90°±5°, 90°±5°, 0° to 20°, or 152° to 180°), a thickness of 0.15λ or less, and a symmetric mode S of Lamb wave ０ The overtone of S ０ 4. The acoustic wave element according to claim 1, wherein a −2 mode is excited.

13. The piezoelectric substrate has an Euler angle of (0°±5°, 0° to 45° or 135° to 180°, 90°±5°), and the fundamental mode of the SH wave is SH ０ The acoustic wave element according to claim 1 , wherein a mode is excited.

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