A micro-electrical-mechanical system (MEMS) guided wave device includes a plurality of electrodes arranged below a piezoelectric layer (e.g., either embedded in a slow wave propagation layer or supported by a suspended portion of the piezoelectric layer) and configured for transduction of a lateral acoustic wave in the piezoelectric layer. The piezoelectric layer permits one or more additions or modifications to be made thereto, such as trimming (thinning) of selective areas, addition of loading materials, sandwiching of piezoelectric layer regions between electrodes to yield capacitive elements or non-linear elastic convolvers, addition of sensing materials, and addition of functional layers providing mixed domain signal processing utility.

A ladder filter comprises series arm bulk acoustic wave resonators electrically connected in series between an input port and an output port and shunt bulk acoustic wave resonators electrically connected between adjacent ones of the series arm bulk acoustic wave resonators and ground, each of the arm bulk acoustic resonators including a central active region and a raised frame region outside of the central active region, each of the series arm bulk acoustic resonators including a piezoelectric film, at least one of the series arm bulk acoustic wave resonators including a layer of oxide disposed directly on the piezoelectric film in the raised frame region, and a metal layer disposed directly on the piezoelectric film in the central active region and on the layer of oxide in the raised frame region, the metal layer having a thickness in the raised frame region no greater than in the central active region.

An acoustic wave device includes a piezoelectric layer and an interdigital transducer disposed on the piezoelectric layer. The interdigital transducer primarily includes Al and includes an additive selected from a group consisting of Nd, Sc, and Ta, and a concentration of the additive in a region opposite to a piezoelectric-layer-side region of the interdigital transducer is higher than a concentration of the additive in the piezoelectric-layer-side region of the interdigital transducer.

An electronic component includes a support member, a piezoelectric film, and an interdigital transducer. The support member includes silicon as a primary component. The piezoelectric film is provided directly or indirectly on the support member. The interdigital transducer includes a plurality of electrode fingers. The plurality of electrode fingers are provided side by side separately from each other. The interdigital transducer is provided on the principal surface of the piezoelectric film. The film thickness of the piezoelectric film is about 3.5 λ or less, where λ denotes the wavelength of an acoustic wave determined by the electrode finger pitch of the interdigital transducer. In the support member, the high-impurity-concentration region is further from the piezoelectric film than the low-impurity-concentration region.

Bulk acoustic wave (BAW) resonators, and particularly top electrodes with step arrangements for BAW resonators are disclosed. Top electrodes on piezoelectric layers are disclosed that include a border (BO) region with a dual-step arrangement where an inner step and an outer step are formed with increasing heights toward peripheral edges of the top electrode. Dielectric spacer layers may be provided between the outer steps and the piezoelectric layer. Passivation layers are disclosed that extend over the top electrode either to peripheral edges of the piezoelectric layer or that are inset from peripheral edges of the piezoelectric layer. Piezoelectric layers may be arranged with reduced thickness portions in areas that are uncovered by top electrodes. BAW resonators as disclosed herein are provided with high quality factors and suppression of spurious modes while also providing weakened BO modes that are shifted farther away from passbands of such BAW resonators.

A bulk acoustic wave filter, a manufacturing method thereof, and a communication device are disclosed. The bulk acoustic wave filter includes a first filter substrate and a second filter substrate; the first filter substrate includes a first base substrate and a first resonator, a first electrode pad and a first auxiliary pad arranged on the first base substrate; the second filter substrate includes a second base substrate and a second resonator, a second electrode pad and a second auxiliary pad arranged on the second base substrate, the first filter substrate is arranged opposite to the second filter substrate, the first electrode pad and the second auxiliary pad are in contact with each other, and the second electrode pad and the first auxiliary pad are in contact with each other.

A resonator element includes: a substrate; and an electrode that includes a first conductive layer provided on a surface of the substrate, and a second conductive layer, provided on the opposite side to the first conductive layer on the substrate side, which is disposed within an outer edge of the first conductive layer when seen in a plan view from a direction perpendicular to the surface.

An acoustic resonator that has a first electrode with a first planar portion. A second electrode having a second planar portion is disposed parallel to the first planar portion. This second electrode has a bifurcated end that defines a gap. A piezoelectric layer is disposed between and contacts both the first planar portion and the second planar portion. Also contacting the piezoelectric layer is the bifurcated end of the second electrode. The gap is formed in the periphery of each resonator within a filter. It is formed in the top electrode, that is typically formed of molybdenum, but could be formed from other metals as well. Unlike a gap between a top electrode and piezoelectric material, the gap recited herein is entirely within the second electrode. This structure is compatible with an inner passivation layer that enables a single crystal piezoelectric layer and a larger bottom electrode.

A BAW resonator with an improved lateral energy confinement is provided. The resonator has a bottom electrode in a bottom electrode layer, a top electrode in a top electrode layer and a piezoelectric layer between the bottom electrode layer and the top electrode layer. The piezoelectric layer comprises piezoelectric materials of different piezoelectric polarities.

An acoustic wave device includes a support substrate, a low-acoustic-velocity film on the support substrate, a piezoelectric layer on the low-acoustic-velocity film, an IDT electrode on the piezoelectric layer, and a high-acoustic-velocity film between the support substrate and the low-acoustic-velocity film. An acoustic velocity of a bulk wave propagating through the low-acoustic-velocity film is lower than an acoustic velocity of a bulk wave propagating through the piezoelectric layer. An acoustic velocity of a bulk wave propagating though the high-acoustic-velocity film is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer. Adhesion between the low-acoustic-velocity film and the support substrate is higher than adhesion between the high-acoustic-velocity film and the support substrate. The high-acoustic-velocity film is between portions of the support substrate and the low-acoustic-velocity film, and a portion of the low-acoustic-velocity film and a portion of the support substrate contact each other.