Resonator devices and filter devices are disclosed. A radio frequency filter includes substrate; a piezoelectric layer; a conductor pattern comprising a plurality of interdigital transducers (IDTs) on the piezoelectric layer; and an acoustic Bragg reflector between the substrate and the piezoelectric layer. The plurality of IDTs comprises a first IDT of first acoustic resonator and a second IDT of a second acoustic resonator. Moreover, a first thickness of the piezoelectric layer under the first IDT is greater than a second thickness of piezoelectric layer under the second IDT.

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.

An acoustic resonator is provided that includes a substrate having a top surface; a piezoelectric layer having a front surface and a back surface; an interdigital transducer (IDT) on the front surface of the piezoelectric layer; and an acoustic Bragg reflector between the top surface of the substrate and the back surface of the piezoelectric layer, the acoustic Bragg reflector comprising two or more layers. Moreover, at least one layer of the two or more layers of the acoustic Bragg reflector comprises a plurality of pedestals that support the back surface of the piezoelectric layer, and spaces are defined between adjacent pedestals of the plurality of pedestals.

A process for fabricating a component includes an operation of transferring at least one layer of one or more piezoelectric or pyroelectric or ferroelectric materials forming part of a donor substrate to a final substrate, the process comprising a prior step of joining the layer to a temporary substrate via production of a fragile separating region between the donor substrate of single-crystal piezoelectric or pyroelectric or ferroelectric material and the temporary substrate, the region comprising at least two layers of different materials in order to ensure two compounds apt to generate an interdiffusion of one or more constituent elements of at least one of the two compounds make contact, the fragile region allowing the temporary substrate to be separated.

Aspects of this disclosure relate to a method of manufacturing a bulk acoustic wave device that includes forming a piezoelectric layer over an electrode such that the piezoelectric layer has a greater magnitude effective piezoelectric coefficient in a main acoustically active region of the bulk acoustic wave device than in a peripheral region of the bulk acoustic wave device. Related bulk acoustic wave devices, filters, multiplexers, radio frequency modules, radio frequency systems, wireless communication devices, and methods are disclosed.

In an acoustic mirror of a bulk-acoustic wave (BAW) device, acoustic energy is reflected at interfaces of layers having different acoustic impedances, and the wavelengths of the acoustic energy reflected at each layer depends on the layer thickness. The acoustic mirror comprises a patterned layer including a first region of a first material and a second region of the first material separated by a second material to reduce an effective thickness of the layer for acoustic reflection. As operating frequencies in wireless devices increase, current manufacturing practices may be unable to produce the correspondingly thinner layers of the acoustic mirror. Thus, the BAW device described herein can be employed to provide a reduced effective thickness for acoustic reflection with layers having an actual thickness that can be formed by existing manufacturing practices. In some examples, the first material and the second material have different acoustic impedances.

One aspect of the present disclosure pertains to a method of forming an acoustic wave device. The method includes forming a reflector stack structure over a substrate, forming a bottom electrode over the reflector stack structure, depositing a first piezoelectric layer over the bottom electrode, patterning the first piezoelectric layer to form a trench exposing a top surface of the bottom electrode and a sloped side surface of the patterned first piezoelectric layer, depositing a second piezoelectric layer in the trench and over the exposed top surface of the bottom electrode and over the first piezoelectric layer, and patterning the second piezoelectric layer to remove portions of the second piezoelectric layer not within the trench.

A bulk acoustic wave resonator, a method for manufacturing the same and an electronic device are provided, and belong to the field of communication technology. The bulk acoustic wave resonator includes: a base substrate, a first electrode, a piezoelectric layer, and a second electrode. The bulk acoustic wave resonator further includes: a first bias resistance layer on a side of the first electrode close to the base substrate, and a first electric isolation layer between the first bias resistance layer and the first electrode; the first bias resistance layer is made of a material with a high resistivity; and/or a second bias resistance layer on a side of the second electrode away from the base substrate, and a second electric isolation layer between the second bias resistance layer and the second electrode; and the second bias resistance layer is made of a material with a high resistivity.

An acoustic-wave device includes a first electrode located over a substrate. A piezoelectric film is located over the first electrode and at least partially overlaps the first electrode. A second electrode is located over the piezoelectric film and at least partially overlaps the first electrode and the piezoelectric film. A temperature sensor is located in a same layer level as the first or second electrode. A heater may also be located in a same layer level as the first electrode. A closed-loop system may operate using the temperature sensor and the heater to maintain an operating temperature that provides highly stable operation.

As disclosed herein, methods of forming a piezoelectric resonator device can include forming a first stack of piezoelectric layers having alternating opposing ferroelectric polarizations comprising the following operations: (a) depositing a first material, including metal and nitrogen atoms, on a surface to form a first piezoelectric layer having a first ferroelectric polarization, (b) forming a first layer including Al on the first piezoelectric layer, (c) depositing a second material including the metal and the nitrogen atoms on the first layer to form a second piezoelectric layer having the first ferroelectric polarization, (d) forming first poling electrodes electrically laterally spaced apart from one another on a surface of the second piezoelectric layer and (e) applying a voltage across the first poling electrodes to change the first ferroelectric polarization of the second piezoelectric layer to a second ferroelectric polarization that is opposite to the first ferroelectric polarization.