A filter device is provided that includes a substrate; a piezoelectric layer coupled to the substrate either directly or via one or more intermediate layers; a first interdigital transducer (IDT) of a first bulk acoustic resonator device on the piezoelectric layer and having interleaved fingers over a first cavity the first bulk acoustic resonator device; a second IDT of a second bulk acoustic resonator device on the piezoelectric layer and having interleaved fingers over a second cavity of the second bulk acoustic resonator device; a first dielectric layer having a first thickness disposed between the interleaved fingers of the first IDT; and a second dielectric layer having a second thickness disposed between the interleaved fingers of the second IDT. The first thickness is greater than the second thickness.

As disclosed herein, methods of forming piezoelectric layers having alternating polarizations and related bulk acoustic wave filter devices. Pursuant to these embodiments, a method of forming a piezoelectric resonator device can include forming a first material, including metal and nitrogen atoms, using a first process to provide a first piezoelectric layer having the metal and the nitrogen atoms arranged in a first polar orientation, to establish a first polarization for the first piezoelectric layer and forming a second material, including the metal and the nitrogen atoms on the first piezoelectric layer, using a second process to provide a second piezoelectric layer having the metal and the nitrogen atoms arranged in a second polar orientation, to establish a second polarization for the second piezoelectric layer that is opposite of the first polarization.

In a piezoelectric resonator manufacturing method, a sacrificial layer is formed on a back surface of a piezoelectric substrate. A support layer is formed on the back surface of the piezoelectric substrate so as to cover the sacrificial layer. A support layer as a piezoelectric resonator is formed by flattening the support layer. A recess in which the surface of the sacrificial layer is recessed with respect to the surface of the support layer is formed by abrading the surfaces of the support layer and the sacrificial layer. The recess extends to a vicinity of a boundary surface between the support layer and the sacrificial layer in the support layer. A support substrate is adhered to the surfaces of the support layer including the recess and the sacrificial layer via an adhesive material.

A method for manufacturing a piezoelectric device including a piezoelectric thin film, a support member, a first electrode, and a cavity formed at a support member side of the first electrode between the piezoelectric thin film and the support member includes forming a sacrificial layer in an area to define the cavity, forming an etching adjustment layer which adjusts progress of etching in a region where the first electrode is exposed to a side of the piezoelectric thin film, simultaneously forming a through hole through which a portion of the sacrificial layer is exposed to the side of the piezoelectric thin film and an opening which the first electrode is exposed to the side of the piezoelectric thin film by etching the piezoelectric thin film and the etching adjustment layer, and removing the sacrificial layer through the through hole.

A lower electrode and an adhesive layer made of an insulator are formed on a back surface on the ion implantation layer side of a piezoelectric single crystal substrate. A supporting substrate in which sacrificial layers made of a conductive material have been formed is bonded to the surface of the adhesive layer. By heating the composite body including the piezoelectric single crystal substrate, the lower electrode, the adhesive layer, and the supporting substrate, a layer of the piezoelectric single crystal substrate is detached to form a piezoelectric thin film. A liquid polarizing upper electrode is formed on a detaching interface of the piezoelectric thin film. A pulsed electric field is applied using the polarizing upper electrode and the sacrificial layers as counter electrodes. Consequently, the piezoelectric thin film is polarized.

Disclosed is a bulk acoustic wave resonator (BAWR). The BAWR includes a bulk acoustic wave resonance unit with a first electrode, a second electrode, and a piezoelectric layer. The piezoelectric layer is disposed between the first electrode and the second electrode. An air edge is formed at a distance from a center of the bulk acoustic wave resonance unit.

A method of forming an acoustic resonator includes forming a seed layer on a first electrode layer, forming a piezoelectric layer directly on a surface of the seed layer, and forming a second electrode layer on the piezoelectric layer. The piezoelectric layer includes multiple crystals of piezoelectric material, and the seed layer causes crystal axis orientations of the crystals to be substantially perpendicular to the surface of the seed layer.

An acoustic resonator device comprises: a substrate comprising a cavity or an acoustic mirror; a first electrode disposed over the substrate; a piezoelectric layer disposed over the first electrode; and a second electrode disposed over the piezoelectric layer. The first electrode or the second electrode, or both, are made of an electrically conductive material having a positive temperature coefficient.

A method of manufacturing an integrated circuit. This method includes forming an epitaxial material comprising single crystal piezo material overlying a surface region of a substrate to a desired thickness and forming a trench region to form an exposed portion of the surface region through a pattern provided in the epitaxial material. Also, the method includes forming a topside landing pad metal and a first electrode member overlying a portion of the epitaxial material and a second electrode member overlying the topside landing pad metal. Furthermore, the method can include processing the backside of the substrate to form a backside trench region exposing a backside of the epitaxial material and the landing pad metal and forming a backside resonator metal material overlying the backside of the epitaxial material to couple to the second electrode member overlying the topside landing pad metal.

A bulk acoustic wave resonator, a manufacturing method thereof and a filter are provided and belong to the technical field of radio frequency micro-electro-mechanical system. The resonator includes a dielectric substrate, a first electrode, a piezoelectric layer, and a second electrode. The dielectric substrate has a first cavity penetrating through the dielectric substrate in a thickness direction thereof, and the first cavity includes a first opening penetrating through the first surface, and a second opening penetrating through the second surface. The first opening includes first sides sequentially arranged in a clockwise direction, and first connecting sides each connecting two adjacent first sides; the second opening includes second sides sequentially arranged in a clockwise direction, and second connecting sides each connecting two adjacent second sides. The first sides are in one-to-one correspondence with the second sides, and the first connecting sides are in one-to-one correspondence with the second connecting sides.