Abstract: 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 interleaved fingers of an interdigital transducer 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 connected to a respective pad of the second plurality of contact pads. A seal is formed between a perimeter of the piezoelectric plate and a perimeter of the interposer.

Abstract: Acoustic resonator devices, filter devices, and methods of making acoustic resonator devices and filter devices. An acoustic resonator device includes a substrate with a cavity and an alignment pattern in a surface of the substrate. The cavity and the alignment pattern have a same depth. A back surface of a piezoelectric plate is attached to the surface of the substrate. A portion of the piezoelectric plate that spans the cavity forms a diaphragm. An interdigital transducer (IDT) is on a front surface of the piezoelectric plate. Interleaved fingers of the IDT are on the diaphragm.

Abstract: Methods of making acoustic resonator devices and filters are disclosed. A method of fabricating an acoustic resonator device includes fabricating an acoustic resonator chip including: attaching a back surface of a piezoelectric plate to a front surface of a substrate, such that portions of the piezoelectric plate form at least first and second diaphragms spanning at least first and second cavities, and forming a first conductor pattern as one or more conductor layers on the piezoelectric plate. The first conductor pattern includes at least first and second interdigitated transducers (IDTs) and a first plurality of contact pads. The method further includes fabricating an interposer having front and back surface and a second plurality of contact pads on the interposer back surface, forming conductive balls, and bonding each of the first plurality of contact pads to a respective pad of the second plurality of contact pads using the respective conductive ball.

Abstract: 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.

Abstract: Acoustic filters, resonators and methods are disclosed. An acoustic filter device 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 piezoelectric plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer is formed on the front surface of the piezoelectric plate with interleaved fingers of the IDT disposed on the diaphragm. At least a portion of a perimeter of the cavity is curved, and the perimeter of the cavity is corner-less.

Abstract: 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.

Abstract: 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.

Abstract: Acoustic resonator devices and filters, and methods of making the same. An acoustic resonator includes a piezoelectric plate and an interdigital transducer (IDT) including interleaved fingers on the piezoelectric plate. The piezoelectric plate and the IDT are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode within the piezoelectric plate. The acoustic resonator further includes a front-side dielectric layer on the piezoelectric plate between the fingers of the IDT, wherein a resonance frequency of the acoustic resonator device has an inverse dependence on a thickness of the front-side dielectric layer.

Abstract: Filter devices and methods are disclosed. A filter device includes a substrate having a surface. A back surface of a single-crystal piezoelectric plate is attached to the surface of the substrate, portions of the single-crystal piezoelectric plate forming a plurality of diaphragms spanning respective cavities in the substrate. A conductor pattern is formed on a front surface of the piezoelectric plate, the conductor pattern including a plurality of interdigital transducers (IDTs) of a plurality of resonators. Interleaved fingers of at least a first IDT of the plurality of IDTs are disposed on a diaphragm having a first thickness, and interleaved fingers of at least a second IDT of the plurality of IDTs are disposed on a diaphragm having a second thickness less than the first thickness.

Abstract: 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.

Abstract: Acoustic resonator devices and filters are disclosed. An acoustic resonator device includes a substrate having a surface, wherein the surface comprises an etched cavity, and a single-crystal piezoelectric plate having parallel front and back surfaces, the back surface attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm that spans the cavity. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate, wherein interleaved fingers of the IDT are aligned with the cavity such that the interleaved fingers are disposed on the diaphragm. The IDT is configured to excite a primary acoustic mode in the diaphragm in response to a radio frequency signal applied to the IDT. The substrate further includes an alignment pattern that is separate from resonator cavities to facilitate alignment of the piezoelectric plate and the interleaved fingers, the alignment pattern comprising a trench.

Abstract: An acoustic resonator is fabricated by forming a patterned first photoresist mask on a piezoelectric plate at locations of a desired interdigital transducer (IDT) pattern. An etch-stop layer is then deposited on the plate and first photoresist mask. The first photoresist mask is removed to remove parts of the etch-stop and expose the plate. An IDT conductor material is deposited on the etch stop and the exposed plate. A patterned second photoresist mask is then formed on the conductor material at locations of the IDT pattern. The conductor material is then etched over and to the etch-stop to form the IDT pattern which has interleaved fingers on a diaphragm to span a substrate cavity. A portion of the plate and the etch-stop form the diaphragm. The etch-stop and photoresist mask are impervious to this etch. The second photoresist mask is removed to leave the IDT pattern.

Abstract: An acoustic resonator is fabricated by forming a patterned first photoresist mask on a piezoelectric plate at locations of a desired interdigital transducer (IDT) pattern. An etch-stop layer is then deposited on the plate and first photoresist mask. The first photoresist mask is removed to remove parts of the etch-stop and expose the plate. An IDT conductor material is deposited on the etch stop and the exposed plate. A patterned second photoresist mask is then formed on the conductor material at locations of the IDT pattern. The conductor material is then etched over and to the etch-stop to form the IDT pattern which has interleaved fingers on a diaphragm to span a substrate cavity. A portion of the plate and the etch-stop form the diaphragm. The etch-stop and photoresist mask are impervious to this etch. The second photoresist mask is removed to leave the IDT pattern.

Abstract: Resonator devices, filter devices, and methods of fabrication are disclosed. A resonator device includes a substrate and a single-crystal piezoelectric plate having parallel front and back surfaces. An acoustic Bragg reflector is sandwiched between a surface of the substrate and the back surface of the single-crystal piezoelectric plate. An interdigital transducer (IDT) is formed on the front surface. The IDT and the single-crystal piezoelectric plate are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode within the single-crystal piezoelectric plate. The acoustic Bragg reflector is configured to reflect the primary shear acoustic mode over a frequency range including a resonance frequency and an anti-resonance frequency of the acoustic resonator device.

Abstract: 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.

Abstract: Resonator devices are disclosed. An acoustic resonator device includes a piezoelectric plate having front and back surfaces, an acoustic Bragg reflector on the back surface, and an interdigital transducer (IDT) on the front surface. The acoustic Bragg reflector reflects a primary shear acoustic mode excited by the IDT in the piezoelectric plate over a frequency range including a resonance frequency and an anti-resonance frequency of the acoustic resonator device.

Abstract: Methods of fabricating acoustic resonators are disclosed. A back surface of a piezoelectric plate is bonded to a surface of a substrate. Thickness measurements are made at a plurality of positions on the piezoelectric plate. Excess material is removed from the front surface of the piezoelectric plate in accordance with the thickness measurements to improve a thickness uniformity of the piezoelectric plate. A conductor pattern is formed on the front surface, the conductor pattern including a plurality of interdigital transducers (IDTs) of a plurality of resonators. Cavities are formed in the substrate such that portions of the single-crystal piezoelectric plate form a plurality of diaphragms spanning respective cavities, wherein interleaved fingers of each IDT of the plurality of IDTs are disposed on a respective one of the plurality of diaphragms.

Abstract: Acoustic filters, resonators and methods are disclosed. An acoustic resonator device includes a substrate having a surface. A back surface of a single-crystal piezoelectric plate is 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. A conductor pattern is formed on the front surface of the piezoelectric plate, the conductor pattern including an interdigital transducer (IDTs), interleaved fingers of the IDT disposed on the diaphragm. A pitch of the interleaved fingers and a mark of the interleaved fingers are set in combination such that a resonance frequency of the acoustic resonator is equal to a predetermined target frequency.

Abstract: Acoustic filters, resonators and methods are disclosed. An acoustic resonator includes a substrate and a piezoelectric plate including a diaphragm that spans a cavity in the substrate. A conductor pattern includes an interdigital transducer (IDT) with interleaved parallel fingers on the diaphragm. A ratio of a width of either of two adjacent parallel fingers and a center-to-center spacing between the two adjacent parallel fingers is greater than or equal to 0.2 and less than or equal to 0.3.

Abstract: Acoustic filters, resonators and methods are disclosed. An acoustic resonator includes a substrate and a piezoelectric plate includes a diaphragm that spans a cavity in the substrate. A conductor pattern includes an interdigital transducer (IDT) with interleaved parallel fingers on the diaphragm. A center-to-center spacing between two adjacent parallel fingers is greater than or equal to 2.5 times a thickness of the diaphragm and less than or equal to 15 times the diaphragm thickness.