Murata Manufacturing Co., Ltd.

Albert Cardona

Andrew Kay

Chris O'Brien

Sean McHugh

Patrick J Turner

Greg Dyer

John Pandelis Koulakis

Ventsislav Yantchev

Robert B Hammond

Douglas Jachowski

Viktor Plesski

Bryant Garcia

Soumya Yandrapalli

Jesson John

Garrett Williams

Gregory L Hey-Shipton

Wei Yang

Luke Myers

Marie Chantal Mukandatimana

Chris O′Brien

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.

Filter device

Acoustic resonators, filters, and methods. An acoustic resonator includes a substrate, a piezoelectric plate, and a diaphragm including a portion of the piezoelectric plate spanning a cavity in a substrate. An interdigital transducer (IDT) on a front surface of the piezoelectric plate includes first and second sets of interleaved interdigital transducer (IDT) fingers extending from first and second busbars respectively. The interleaved IDT fingers extend onto the diaphragm. Overlapping portions of the interleaved IDT fingers define an aperture of the acoustic resonator. First and second dielectric strips are on the front surface of the piezoelectric plate. Each dielectric strip has a first portion under the IDT fingers in a respective margin of the aperture and a second portion extending into a gap between the respective margin and the respective busbar.

Transversely-excited film bulk acoustic resonator with buried oxide strip acoustic confinement structures

Acoustic resonators, filters, and methods. A filter includes a piezoelectric plate supported by a substrate; and three or more diaphragms of the piezoelectric plate spanning a respective cavity in the substrate. A conductor pattern on the plate has interdigital transducers (IDTs) of three or more acoustic resonators. Each IDT has two sets of interleaved fingers extending from two busbars respectively. Overlapping portions of the fingers define an aperture of each acoustic resonator. Sometimes, each of the resonators has two dielectric strips that overlap the IDT fingers in first and second margins of the aperture and that extend into first and second gaps between the first and second margins and the busbars. Other times, the first and second dielectric strips are on the front surface of the plate, have a first portion under the IDT fingers and have a second portion extending into a gap between the margins and the busbars.

Transversely-excited film bulk acoustic resonator with oxide strip acoustic confinement structures

Methods of fabricating filter devices are disclosed. A back surface of a piezoelectric plate having a first thickness is attached to a substrate. The front surface of the piezoelectric plate is selectively etched to thin a portion of the piezoelectric plate from the first thickness to a second thickness less than the first thickness. Cavities are formed in the substrate such that portions of the piezoelectric plate form a plurality of diaphragms spanning respective cavities. A conductor pattern is formed on the front surface. The conductor pattern includes a first interdigital transducer (IDT) with interleaved fingers on a first diaphragm having the first thickness and a second IDT with interleaved fingers on a second diaphragm having the second thickness.

Transversely-excited film bulk acoustic resonator with multiple diaphragm thicknesses and fabrication method

An acoustic resonator device is formed using a wafer-to-wafer bonding process by etching recesses into a first surface of a piezoelectric substrate, a depth of the recesses greater than a target piezoelectric membrane thickness; then wafer-to-wafer bonding the first surface of the piezoelectric substrate to a handle wafer using a releasable bonding method. The piezoelectric substrate is then thinned to the target piezoelectric membrane thickness to form a piezoelectric plate and at least one conductor pattern is formed on the thinned piezoelectric plate. The side of the thinned piezoelectric plate having the conductor pattern is bonded to a carrier wafer using a metal-to-metal wafer bonding process and the handle wafer is removed.

Transversely-excited film bulk acoustic resonator fabrication using wafer-to-wafer bonding

An acoustic resonator device with low thermal impedance has a substrate and a single-crystal piezoelectric plate having a back surface attached to a top surface of the substrate via a bonding oxide (BOX) layer. An interdigital transducer (IDT) formed on the front surface of the plate has interleaved fingers disposed on the diaphragm, the overlapping distance of the interleaved fingers defining an aperture of the resonator device. Contact pads are formed at selected locations over the surface of the substrate to provide electrical connections between the IDT and contact bumps to be attached to the contact pads. The piezoelectric plate is removed from at least a portion of the surface area of the device beneath each of the contact pads to provide lower thermal resistance between the contact bumps and the substrate.

Transversely-excited film bulk acoustic resonator with reduced substrate to contact bump thermal resistance

A filter device with multiple piezoelectric plate thicknesses if fabricated on a single chip by bonding a piezoelectric plate to a surface of a substrate having swimming pool shunt and series cavities. Non-selected areas of the plate have a thickness for shunt resonators and form shunt membranes of the plate that span the swimming pool shunt cavities. Selected areas of a back surface of the plate have a thickness for series resonators and form series membranes of the plate that span the swimming pool series cavities but not the swimming pool shunt cavities. The thickness for series resonators is thinner than that for shunt resonators. Shunt interdigital transducers (IDTs) are on a front surface of the plate over the swimming pool shunt cavities; and series IDTs are on a front surface of the plate over the swimming pool series cavities.

Transversely-excited film bulk acoustic resonators with multiple piezoelectric membrane thicknesses on the same chip

Transversely-excited film bulk acoustic resonator

An acoustic resonator device is formed using a sacrificial layer and a front side etched cavity by forming a recess in a silicon substrate with a trap-rich top layer and filling the recess with sacrificial silicon nitride. A bonding oxide (BOX) layer is formed over the trap-rich layer and the sacrificial silicon nitride filled recess and a piezoelectric plate is bonded to the BOX layer. The sacrificial silicon nitride is then removed to form a cavity by using an etchant introduced through holes in the piezoelectric plate and BOX layer without removing the BOX layer from over the cavity.

Substrate processing and membrane release of transversely-excited film bulk acoustic resonator using a sacrificial tub

An acoustic resonator is fabricated with multiple piezoelectric plate thicknesses on a single chip. After conductor patterns are formed on a piezoelectric plate, the plate is bonded to a sacrificial substrate, with the conductor patterns facing the sacrificial substrate. The piezoelectric plate is then thinned to a desired thickness for shunt resonators. A mask is applied to the surface of the plate and selected areas of the piezoelectric plate are further thinned to a desired thickness for series resonators to form a thinned piezoelectric plate. A substrate with swimming pool cavities is bonded to the thinned piezoelectric plate, and the sacrificial substrate is removed.

An acoustic resonator device is formed using sacrificial polysilicon pillar by forming a polysilicon pillar on a substrate and depositing a dielectric layer to bury the polysilicon pillar and planarizing the surface of the dielectric layer. A piezoelectric plate is bonded to the planarized surface of the dielectric layer and thinned to a target piezoelectric membrane thickness. At least one conductor pattern is formed on the thinned piezoelectric plate and the polysilicon pillar is then removed using an etchant introduced through holes in the piezoelectric plate to form an air cavity where the pillar was removed.

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Santa Barbara, CA, United States of America

Albert Cardona