Acoustic resonator devices and filters are disclosed. An acoustic resonator includes a substrate having a surface 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 a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT 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. A direction of acoustic energy flow of the primary acoustic mode is substantially orthogonal to the front and back surfaces of the diaphragm. The diaphragm is contiguous with the piezoelectric plate around at least 50% of a perimeter of the cavity.

A method of forming a piezoelectric thin film can include depositing a material on a first surface of a Si substrate to provide a stress neutral template layer. A piezoelectric thin film including a Group III element and nitrogen can be sputtered onto the stress neutral template layer and a second surface of the Si substrate that is opposite the first surface can be processed to remove that Si substrate and the stress neutral template layer to provide a remaining portion of the piezoelectric thin film. A piezoelectric resonator can be formed on the remaining portion of the piezoelectric thin film.

Acoustic resonator devices, filter devices, and methods of fabrication are disclosed. 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 that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT 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. At least a portion of an edge of the diaphragm is at an oblique angle to the fingers.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. A first patterned electrode is deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the first electrode and a planarized support layer is deposited over the sacrificial layer, which is then bonded to a substrate wafer. The crystalline substrate is removed and a second patterned electrode is deposited over a second surface of the film. The sacrificial layer is etched to release the air reflection cavity. Also, a cavity can instead be etched into the support layer prior to bonding with the substrate wafer. Alternatively, a reflector structure can be deposited on the first electrode, replacing the cavity.

A system for a wireless communication infrastructure using single crystal devices. The wireless system can include a controller coupled to a power source, a signal processing module, and a plurality of transceiver modules. Each of the transceiver modules includes a transmit module configured on a transmit path and a receive module configured on a receive path. The transmit modules each include at least a transmit filter having one or more filter devices, while the receive modules each include at least a receive filter. Each of these filter devices includes a single crystal acoustic resonator device formed with a thin film transfer process with at least a first electrode material, a single crystal material, and a second electrode material. Wireless infrastructures using the present single crystal technology perform better in high power density applications, enable higher out of band rejection (OOBR), and achieve higher linearity as well.

Techniques are disclosed for forming high frequency film bulk acoustic resonator (FBAR) devices using epitaxially grown piezoelectric films. In some cases, the piezoelectric layer of the FBAR may be an epitaxial III-V layer such as an aluminum nitride (AlN) or other group III material-nitride (III-N) compound film grown as a part of a III-V material stack, although any other suitable piezoelectric materials can be used. Use of an epitaxial piezoelectric layer in an FBAR device provides numerous benefits, such as being able to achieve films that are thinner and higher quality compared to sputtered films, for example. The higher quality piezoelectric film results in higher piezoelectric coupling coefficients, which leads to higher Q-factor of RF filters including such FBAR devices. Therefore, the FBAR devices can be included in RF filters to enable filtering high frequencies of greater than 3 GHz, which can be used for 5G wireless standards, for example.

A resonator may include a first dielectric member, a second dielectric member, and a composite member. The first dielectric member may have a first cavity. The composite member may include a piezoelectric layer and may overlap at least one of the first dielectric member and the second dielectric member. At least one of the second dielectric member and the composite member may have a second cavity. The piezoelectric layer may be positioned between the first cavity and the second cavity. A projection of the first cavity in a direction perpendicular to a flat side of the first dielectric member and a projection of the second cavity in the direction may intersect each other to form a polygon. No two edges of the polygon may be parallel to each other.

An acoustic resonator includes: a resonating unit including a piezoelectric layer, a first electrode disposed on a lower side of the piezoelectric layer, and a second electrode disposed on an upper side of the piezoelectric layer; a substrate disposed below the resonating unit; a support unit forming a cavity between the substrate and the resonating unit; and a pillar extending through the cavity and connecting the resonating unit to the substrate. The resonating unit further includes a first insertion layer disposed above the pillar.

A method for manufacturing a semiconductor apparatus includes: on a base substrate, forming an isolation trench layer, a first dielectric layer, a lower electrode layer and a second dielectric layer; forming a piezoelectric film and an upper electrode layer in an opening in the second dielectric layer; forming a third dielectric layer; forming a first cavity in the third dielectric layer to expose at least part of the upper electrode layer; bonding a first assistant substrate to seal the first cavity; removing a part of the base substrate to expose the isolation trench layer; forming a fourth dielectric layer on a side of the isolation trench; and etching through the fourth dielectric layer, the isolation trench layer, the first dielectric layer to form a second cavity beneath the lower electrode layer, plan views of the first and second cavities providing an overlapped region having a polygon shape without parallel sides.

An acoustic wave resonator includes: a substrate; a resonating portion formed on a first surface of the substrate; a metal pad connected to the resonating portion through a via hole formed in the substrate; and a protective layer disposed on a second surface of the substrate and including a plurality of layers, wherein the plurality of layers includes an internal protective layer directly in contact with the second surface of the substrate and formed of an insulating material including an adhesion that is stronger than an adhesion of other layers, among the plurality of layers.