An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, a functional electrode on the piezoelectric layer, first and second electrode films on the piezoelectric layer, facing each other, and having different electric potentials from each other, and a dielectric film between at least one of at least a portion of the first electrode film and the piezoelectric layer and at least a portion of the second electrode film and the piezoelectric layer.

An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, a functional electrode on the piezoelectric layer, and first and second electrode films on the piezoelectric layer, facing each other, and having different electric potentials from each other. When a region between the first and second electrode films in a plan view is an inter-electrode film region, and a region overlapping with the first electrode film or the second electrode film in a plan view is an electrode film underlying region, a thickness of the piezoelectric layer in at least a portion of the inter-electrode film region is smaller than a thickness of the piezoelectric layer in the electrode film underlying region.

An acoustic resonator device includes a substrate having a surface and a piezoelectric plate having front and back surfaces, with the back surface attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm. Stripes of a dielectric material formed over the plate in gaps between ends of the interleaved fingers and opposing busbars of the IDT.

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.

A MEMS resonator is operated at its parallel resonance frequency. An acoustic wave is propagated laterally away from a central region of the MEMS resonator through a piezoelectric layer of the MEMS resonator. The propagating acoustic wave is attenuated with concentric confiners that surround and are spaced apart from a perimeter of an electrode that forms the MEMS resonator.

A micro-transfer printable transverse bulk acoustic wave filter comprises a piezoelectric filter element having a top side, a bottom side, a left side, and a right side disposed over a sacrificial portion on a source substrate. A top electrode is in contact with the top side and a bottom electrode is in contact with the bottom side. A left acoustic mirror is in contact with the left side and a right acoustic mirror is in contact with the right side. The thickness of the transverse bulk acoustic wave filter is substantially less than its length or width and its length can be greater than its width. The transverse bulk acoustic wave filter can be disposed on, and electrically connected to, a semiconductor substrate comprising an electronic circuit to control the transverse bulk acoustic wave filter and form a composite heterogeneous device that can be micro-transfer printed.

A bulk acoustic resonator includes: a substrate including an upper surface on which a substrate protection layer is disposed; and a membrane layer forming a cavity together with the substrate, wherein a thickness deviation of either one or both of the substrate protection layer and the membrane layer is 170 Å or less.

There is disclosed acoustic resonators and filter devices. An acoustic resonator device includes a piezoelectric plate, and an interdigital transducer (IDT) formed on a front surface of the piezoelectric plate. The IDT includes interleaved fingers. At least one of the interleaved fingers includes a first layer adjacent the piezoelectric plate and a second layer over the first layer, wherein a width of the first layer is constant, and wherein a width of the second layer varies along a length of the at least one interleaved finger.

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.

Acoustic resonators and filter devices, and methods of making acoustic resonators and filter devices. An acoustic resonator includes a substrate having a surface and a single-crystal piezoelectric plate having front and back surfaces, the back surface attached to the surface of the substrate except for a portion of the plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface with interleaved fingers of the IDT on the diaphragm. The plate and the IDT are configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm. The fingers include a first layer proximate the diaphragm, and a second layer over the first layer. The first and second layers are different metals. A transverse acoustic impedance of the second layer is higher than a transverse acoustic impedance of the first layer.