An electroacoustic device includes, stacked in a direction a silicon-based substrate, a first electrode, a piezoelectric layer with the basis of a perovskite taken from among lithium niobate LiNbO3, lithium tantalum LiTaO3, or an Li(Nb,Ta)O3 alloy, on the first electrode, a second electrode disposed on the piezoelectric layer. Advantageously, the first electrode is made of a nitride-based electrically conductive refractory material, such as TiN, VN, TaN. The invention also relates to a method for producing such a device.

Filter devices are disclosed. A filter device includes a piezoelectric plate comprising a supported portion, a first diaphragm, and a second diaphragm. The supported portion is attached to a substrate and the first and second diaphragms spans respective cavities in the substrate. A first interdigital transducer (IDT) has interleaved fingers on the first diaphragm. A second interdigital transducer (IDT) has interleaved fingers on the second diaphragm. A first dielectric layer is between the interleaved fingers of the first IDT, and a second dielectric layer is between the interleaved fingers of the second IDT. A thickness of the first dielectric layer is greater than a thickness of the second dielectric layer. The piezoelectric plate and the first and second IDTs are configured such that radio frequency signals applied to first and second IDTs excite primary shear acoustic modes in the respective diaphragms.

A piezoelectric film including a piezoelectric body configured to extract radio waves of a required frequency by resonance is provided. The piezoelectric body is based on either of ScAlN or AlN, and an X-ray rocking curve full-width at half-maximum (FWHM) of the piezoelectric body in a lattice plane with a Miller index of (11-20) is not more than 10°.

An acoustic wave device includes: a piezoelectric substrate; electrodes sandwiching the piezoelectric substrate and exciting a thickness shear vibration in the piezoelectric substrate; and an edge region that is a region surrounding a center region of a resonance region, wherein a first region of the edge region is located on both sides of the center region in a first direction substantially parallel to a displacement direction of a thickness shear vibration, a second region of the edge region is located on both sides of the center region in a second direction substantially perpendicular to the first direction, a width of the second region is different from a width of the first region, and acoustic velocities of acoustic waves in the piezoelectric substrate in the first and second regions are less than that in the piezoelectric substrate in the center region.

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate, a lithium niobate plate having front and back surfaces, wherein Euler angles of the lithium niobate plate are [0°, β, 0°], where β is greater than or equal to 0° and less than or equal to 60°, and an acoustic Bragg reflector between the surface of the substrate and the back surface of the lithium niobate plate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate. At least one finger of the IDT is disposed in a groove in the lithium niobate plate.

An acoustic wave device includes a piezoelectric layer and a pair of electrodes. In a cross-section including first and second directions, at least one electrode of the pair of electrodes includes top, bottom, first side, and second side surfaces, the bottom surface being opposed to the top surface and closer to the piezoelectric layer than the top surface. A first angle between the first side surface and the first main surface is different from a second angle between the second side surface and the first main surface, and at least one of the first angle and the second angle is about 80° or larger.

An acoustic wave device includes a piezoelectric layer including first and second main surfaces and made of lithium niobate or lithium tantalate, and an interdigital transducer electrode on the first main surface and including multiple electrode fingers. d/p is about 0.5 or less where d is a thickness of the piezoelectric layer, and p is a distance between centers of adjacent electrode fingers. The electrode fingers include first and second electrode films, which include first and second surfaces and a side surface. Θ1≠Θ2 is satisfied and W1>W2 is satisfied, where Θ1 and Θ2 are angles between the side surfaces and the first surfaces of the first and second electrode films, and W1 and W2 are widths of the first and second electrode films.

An acoustic filter includes a piezoelectric plate on a substrate. Portions of the piezoelectric plate form one or more diaphragms, each diaphragm spanning a respective cavity in the substrate. A conductor pattern on a front surface of the piezoelectric plate includes interdigital transducers (IDTs) of acoustic resonators including a shunt resonator and a series resonator. Interleaved fingers of each IDT are on a diaphragm of the one or more diaphragms. A first dielectric layer with a first thickness is between the fingers of the IDT of the shunt resonator, and a second dielectric layer with a second thickness less than the first thickness is between the fingers of the IDT of the series resonator. The piezoelectric plate and the IDTs are configured such that radio frequency signals applied to the IDTs excite respective primary shear acoustic modes within the diaphragms.

A composite substrate 10 includes a first substrate 10 comprised of a piezoelectric single crystal and a second substrate 20 comprised of a silicon single crystal bonded to the first substrate 10. In the second substrate, a planar orientation is (111), and ψ of Euler angles (φ, θ, ψ) is offset from 0°. Due to this, a bulk wave spurious is reduced in a specific frequency band.

An acoustic wave element which can be reduced in size and produced relatively easily, practically used without using harmful substances, and can suppress a surface acoustic wave propagation loss, which has an excellent temperature coefficient of frequency and a velocity dispersion characteristic, and with which an increase in the reflection coefficient of interdigital transducers can be suppressed, and a method for manufacturing the acoustic wave element are provided. The acoustic wave element includes a pair of electrodes provided on both surfaces of a piezoelectric substrate, and a dielectric film provided on a first surface of the piezoelectric substrate so as to cover the electrode. The acoustic wave element alternatively includes interdigital transducers provided on a first surface of the piezoelectric substrate, and a dielectric film provided on the interdigital transducers, a gap between the interdigital transducers, and/or a second surface of the piezoelectric substrate.