A microelectromechanical resonator device is provided having two-dimensional resonant rods. The resonator device has a piezoelectric layer formed with a plurality of alternating rods and trenches. A bottom electrode is in contact with a bottom surface of the piezoelectric layer. A top electrode metal grating of conductive strips is aligned in contact with corresponding rods of the piezoelectric layer.

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate, a lithium niobate plate having front and back surfaces, wherein Euler angles of the lithium niobate plate are [0°, β, 0° ], where β is greater than or equal to 0° and less than or equal to 60°, and an acoustic Bragg reflector between the surface of the substrate and the back surface of the lithium niobate plate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate. At least one finger of the IDT is disposed in a groove in the lithium niobate plate.

A filter device is provided that includes a substrate, a piezoelectric plate attached to the substrate; interdigital transducers (IDTs) of a plurality of resonators, respectively, that each have interleaved fingers at respective diaphragms of the one piezoelectric plate disposed over one or more cavities; and a dielectric layer over at least one surface of the respective diaphragms. For at least two resonators, the dielectric layer has a thickness distribution that includes a first thickness layer and a second thickness layer over the first thickness layer, and the second thickness layer of a first resonator of the at least two resonators has a coverage distribution over the first thickness layer that is different than a coverage distribution of a second resonator of the at least two resonators.

A bulk acoustic resonator operable in a bulk acoustic mode includes a resonator body mounted to a separate carrier that is not part of the resonator body. The resonator body includes a piezoelectric layer, a device layer, and a top conductive layer on the piezoelectric layer opposite the device layer. The piezoelectric layer is a single crystal of LiNbO.sub.3 cut at an angle of 130°±30°. A surface of the device layer opposite the piezoelectric layer is for mounting the resonator body to the carrier.

The disclosed technology generally relates to quartz crystal devices and more particularly to quartz crystal devices configured to vibrate in torsional mode. In one aspect, a quartz crystal device configured for temperature sensing comprises a fork-shaped quartz crystal comprising a pair of elongate tines laterally extending from a base region in a horizontal lengthwise direction of the fork-shaped quartz crystal. Each of the tines has formed on one or both of opposing sides thereof a vertically protruding line structure laterally elongated in the horizontal lengthwise direction. The quartz crystal device further comprises a first electrode and a second electrode formed on the one or both of the opposing sides of each of the tines and configured such that, when an electrical bias is applied between the first and second electrodes, the fork-shaped quartz crystal vibrates in a torsional mode in which each of the tines twists about a respective axis extending in the horizontal lengthwise direction.

The disclosed technology generally relates to quartz crystal devices and more particularly to quartz crystal devices configured to vibrate in torsional mode. In one aspect, a quartz crystal device configured for temperature sensing comprises a fork-shaped quartz crystal comprising a pair of elongate tines laterally extending from a base region in a horizontal lengthwise direction of the fork-shaped quartz crystal, wherein each of the tines has formed on one or both of opposing sides thereof a pair of vertically recessed groove structures laterally elongated in the horizontal lengthwise direction, wherein the pair of groove structures are separated in a horizontal widthwise direction by a line structure. The quartz crystal device further comprises a first electrode and a second electrode formed on the one or both of the opposing sides of each of the tines and configured such that, when an electrical bias is applied between the first and second electrodes, the fork-shaped quartz crystal vibrates in a torsional mode in which each of the tines twists about a respective axis extending in the horizontal lengthwise direction.

A transducer structure for a surface acoustic device comprises a composite substrate comprising a piezoelectric layer, a pair of inter-digitated comb electrodes, comprising a plurality of electrode means with a pitch p satisfying the Bragg condition, wherein the inter-digitated comb electrodes are embedded in the piezoelectric layer such that, in use, the excitation of a wave propagating mode in the volume of the electrode means is taking place and is the predominant propagating mode of the structure. The present disclosure relates also to an acoustic wave device comprising at least one transducer structure as described above and to a method for fabricating the transducer structure. The present disclosure relates also to the use of the frequency of the bulk wave propagating in the electrode means of the transducer structure in an acoustic wave device to generate contribution at high frequency, in particular, above 3 GHz.

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.

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. The IDT includes a busbar disposed parallel to the edge of the diaphragm such that the interleaved fingers extend at the oblique angle from the busbar.

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate, a lithium niobate plate having front and back surfaces, wherein Euler angles of the lithium niobate plate are [0°, β, 0°], where β is greater than or equal to 0° and less than or equal to 60°, and an acoustic Bragg reflector between the surface of the substrate and the back surface of the lithium niobate plate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate. At least one finger of the IDT is disposed in a groove in the lithium niobate plate.