# US 12,015,393 B2 · Transversely-excited film bulk acoustic resonator with diaphragm support pedestals > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,393 B2 - Document ID: US12015393B2 - Status: Granted - Kind: B2 - Application number: 17/710,765 - Filed: 2022-03-31 - Published: 2022-07-14 - Granted: 2024-06-18 - Earliest claimed: 2018-06-15 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Andrew Kay; Ventsislav Yantchev; Patrick Turner - Web page: https://patentgrep.com/patent/US12015393B2 ## CPC - H03H 9/02157: {Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness} - H03H 9/171: {implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type} - H03H 9/02: Details - H03H 9/02228: {Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer} - H03H 9/54: comprising resonators of piezoelectric or electrostrictive material (comprising resonators using surface acoustic waves H03H9/64) - H03H 9/568: {consisting of a ladder configuration} - H03H 9/02015: {Characteristics of piezoelectric layers, e.g. cutting angles} - H03H 9/13: for networks consisting of piezoelectric or electrostrictive materials (for networks using surface acoustic waves H03H9/145) - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) ## Abstract Acoustic resonator devices and methods are disclosed. An acoustic resonator device includes a substrate having a surface and a piezoelectric plate having front and back surfaces. The back surface of the 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. 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. One or more diaphragm support pedestals extend between the substrate and the diaphragm within the cavity. ## Claims ### Claim 1 An acoustic resonator device comprising: a substrate having a surface; a piezoelectric layer attached to the surface of the substrate either directly or via one or more intermediate layers and having a portion that forms a diaphragm over a cavity of the acoustic resonator device; an interdigital transducer (IDT) at the piezoelectric layer and comprising interleaved fingers on the diaphragm; and one or more diaphragm support pedestals extending from a bottom surface of the cavity to the diaphragm. ### Claim 2 (depends on 1) The device of claim 1, wherein the one or more diaphragm support pedestals is a portion of substrate that remained after the cavity was etched into the substrate. ### Claim 3 (depends on 1) The device of claim 1, wherein the one or more diaphragm support pedestals is a different material from the substrate. ### Claim 4 (depends on 1) The device of claim 1, wherein: when an RF signal is applied to the IDT, an electric field is formed between the interleaved fingers of the IDT; and each diaphragm support pedestal contacts the piezoelectric layer in an area opposite a respective interleaved finger of the IDT to minimize acoustic energy coupled through the diaphragm support pedestals to the substrate. ### Claim 5 (depends on 1) The device of claim 1, wherein each of the one or more diaphragm support pedestals is aligned with a respective finger of the interleaved fingers of the IDT, wherein the one or more diaphragm support pedestals comprise diaphragm support pedestals aligned with every n fingers of the IDT, and where n is an integer greater than or equal to two and less than or equal to twenty. ### Claim 6 (depends on 1) The device of claim 1, wherein a width of each of the one or more diaphragm support pedestals is less than or equal to a width of each finger of the interleaved fingers of the IDT. ### Claim 7 (depends on 6) The device of claim 6, wherein a length of each of the one or more diaphragm support pedestals is greater than or equal to the width of the diaphragm support pedestals and less than or equal to an aperture of the IDT. ### Claim 8 (depends on 1) The device of claim 1, further comprising a bonding layer sandwiched between the piezoelectric layer and the substrate and between the piezoelectric layer and the one or more diaphragm support pedestals. ### Claim 9 A method of fabricating an acoustic resonator device, comprising: forming a cavity over a substrate, one or more diaphragm support pedestals disposed within the cavity; depositing a bonding layer over the substrate, the cavity, and the one or more diaphragm support pedestals; bonding a piezoelectric layer to the bonding layer such that a portion of the piezoelectric layer forms a diaphragm over the cavity with each of the one or more diaphragm support pedestals extending from a bottom surface of the cavity to the bonding layer; and forming an interdigital transducer (IDT) at the piezoelectric layer such that interleaved fingers of the IDT are disposed on the diaphragm. ### Claim 10 (depends on 9) The method of claim 9, wherein the piezoelectric layer and the IDT are configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm. ### Claim 11 (depends on 9) The method of claim 9, further comprising aligning each of the one or more diaphragm support pedestals with a respective finger of the interleaved fingers of the IDT. ### Claim 12 (depends on 11) The method of claim 11, wherein a width of each of the one or more diaphragm support pedestals is less than or equal to a width of each finger of the interleaved fingers of the IDT. ### Claim 13 A method of fabricating an acoustic resonator device, comprising: depositing a bonding layer over a substrate; forming a cavity in at least one of the substrate and the bonding layer, one or more diaphragm support pedestals disposed within the cavity; bonding a piezoelectric layer to the bonding layer and the one or more diaphragm support pedestals such that a portion of the piezoelectric layer forms a diaphragm over the cavity with each of the one or more diaphragm support pedestals extending from a bottom surface of the cavity to the diaphragm; and forming an interdigital transducer (IDT) at the piezoelectric layer such that interleaved fingers of the IDT are disposed on the diaphragm. ### Claim 14 (depends on 13) The method of claim 13, wherein the piezoelectric layer and the IDT are configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm. ### Claim 15 (depends on 13) The method of claim 13, further comprising aligning each of the one or more diaphragm support pedestals with a respective finger of the interleaved fingers of the IDT. ### Claim 16 (depends on 15) The method of claim 15, wherein a width of each of the one or more diaphragm support pedestals is less than or equal to a width of each finger of the interleaved fingers of the IDT. ### Claim 17 A filter device comprising: a plurality of acoustic resonators that each comprise: a substrate, a piezoelectric layer attached to the substrate either directly or via one or more intermediate layers and having a portion that forms a diaphragm over a cavity of the respective acoustic resonator, an interdigital transducer (IDT) at the piezoelectric layer that includes interleaved fingers on the diaphragm, and at least one diaphragm support pedestal that extends from a surface of the cavity to the diaphragm. ### Claim 18 (depends on 17) The filter device of claim 17, wherein the at least one diaphragm support pedestal of each of the plurality of acoustic resonators is aligned with a respective finger of the interleaved fingers of the IDT, and the at least one diaphragm support pedestal comprises a plurality of diaphragm support pedestals that are aligned with every n fingers of the IDT, where n is an integer greater than or equal to two and less than or equal to twenty. ### Claim 19 (depends on 17) The filter device of claim 17, wherein: a width of the at least one diaphragm support pedestal is less than or equal to a width of a finger of the interleaved fingers of the IDT, and a length of the at least one diaphragm support pedestal is greater than or equal to the width of the at least one diaphragm support pedestal and less than or equal to an aperture of the IDT. ### Claim 20 (depends on 17) The filter device of claim 17, wherein the one or more intermediate layers of each of the plurality of acoustic resonators comprises a bonding layer sandwiched between the respective piezoelectric layer and the substrate.