A piezoelectric device includes a membrane portion including a single-crystal piezoelectric layer, an upper electrode layer, and a lower electrode layer. The upper electrode layer is on a first surface. The lower electrode layer is on a second surface facing at least a portion of the upper electrode layer sandwiching the single-crystal piezoelectric layer. The single-crystal piezoelectric layer includes piezoelectric body cleavage directions extending along a boundary line between a cleavage plane occurring when the single-crystal piezoelectric layer is cleaved and the first surface. When viewed in a vertical direction, at least a portion of an upper electrode outer edge and at least a portion of a lower electrode outer edge are non-parallel to at least one of the piezoelectric body cleavage directions.

Acoustic resonator devices and filters are disclosed. An acoustic resonator chip includes a piezoelectric plate attached to a substrate, a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A first conductor pattern formed on a surface of the piezoelectric plate includes an interdigital transducer with interleaved fingers on the diaphragm, and a first plurality of contact pads. A second conductor pattern is formed on a surface of an interposer, the second conductor pattern including a second plurality of contact pads. Each pad of the first plurality of contact pads is directly bonded to a respective pad of the second plurality of contact pads. A seal is formed between a perimeter of the acoustic resonator chip and a perimeter of the interposer.

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate and a lithium niobate (LN) plate having front and back surfaces and a thickness ts. The back surface faces the substrate. A portion of the LN plate forms a diaphragm spanning a cavity in the substrate. An interdigital transducer (IDT) is on the front surface of the LN plate with interleaved fingers of the IDT on the diaphragm. The LN plate and the IDT are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic wave in the diaphragm. Euler angles of the LN plate are [0°, β, 0°], where 0≤β≤60°. A thickness of the interleaved fingers of the IDT is greater than or equal to 0.8 ts and less than or equal to 2.0 ts.

Acoustic resonator devices and filters are disclosed. An acoustic resonator includes a substrate and a piezoelectric plate having parallel front and back surfaces, the back surface attached to the substrate. A decoupling dielectric layer is on the front surface of the piezoelectric plate. An interdigital transducer (IDT) is formed over the decoupling dielectric layer such that interleaved fingers of the IDT are over a portion of the piezoelectric plate suspended across a cavity formed in the substrate.

Methods of making acoustic resonators and filter devices. A method includes attaching a piezoelectric plate to a substrate, and forming a conductor pattern including an interdigital transducer (IDT) on a portion of the piezoelectric plate that forms a diaphragm spanning a cavity such that interleaved fingers of the IDT are on the diaphragm. The substrate and the piezoelectric plate are the same material.

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 is attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A conductor pattern formed is formed on the front surface of the piezoelectric plate, including an interdigital transducer (IDT) with interleaved fingers of the IDT on the diaphragm. The substrate and the piezoelectric plate are the same material.

Acoustic resonator devices and filters are disclosed. An acoustic resonator chip includes a piezoelectric plate attached to a substrate. Portions of the piezoelectric plate form at least first and second diaphragms spanning respective cavities in the substrate. A first conductor pattern on the surface of the piezoelectric plate includes a first plurality of contact pads and at least first and second IDTs with interleaved fingers of each IDT on respective diaphragms. An interposer includes a second plurality of contacts pads. A plurality of conductive balls bond each of the contact pads of the first plurality of contact pads to respective contact pads of the second plurality of contact pads.

Methods of fabricating acoustic filters are disclosed. The back of a piezoelectric plate is bonded to a surface of a substrate. The thickness of the piezoelectric plate is measured at a plurality of positions. Excess material is removed from the front surface of the piezoelectric plate in accordance with the thickness measurements to improve the thickness uniformity of the piezoelectric plate. After removing the excess material, a conductor pattern including a plurality of ladder filter circuits is formed on the front surface. Each ladder filter circuit includes at least one shunt resonator and at least one series resonator, each of which has an interdigital transducer (IDT). Cavities are formed in the substrate such that portions of the piezoelectric plate form a plurality of diaphragms spanning respective cavities. After the cavities are formed, interleaved fingers of each IDT are on a respective one of the plurality of diaphragms.

An acoustic resonator device includes a conductor pattern formed on a surface of a piezoelectric plate. The conductor pattern includes a first busbar, a second busbar, and n interleaved parallel fingers of an interdigital transducer (IDT), where n is a positive integer. The fingers extend alternately from the first and second busbars. A first finger and an n'th finger are disposed at opposing ends of the IDT. The conductor pattern also includes a first reflector element proximate and parallel to the first finger and a second reflector element proximate and parallel to the n'th finger. When an RF signal is applied between the first and second busbars, the first reflector element is at substantially the same potential as the first finger and the second reflector element is at substantially the same potential as the n'th finger.

A method of manufacturing a quartz crystal element includes the steps of preparing a quartz crystal wafer which has a predetermined cutting angle with respect to a crystal axis of a quartz crystal, and which has a first surface and a second surface having an obverse-reverse relationship, forming a first resist film on the first surface, the first resist film having a first tilted part tilted with respect to the first surface, and being dry-etched together with the quartz crystal, forming a first tilted surface tilted with respect to the first surface by dry-etching the quartz crystal wafer from the first surface side, forming a second resist film on the second surface, the second resist film having a second tilted part tilted with respect to the second surface, and being dry-etched together with the quartz crystal, and forming a second tilted surface tilted with respect to the second surface by dry-etching the quartz crystal wafer from the second surface side, wherein the quartz crystal element which is provided with the first tilted surface and the second tilted surface, and which has a cutting angle different from the predetermined cutting angle is formed.