An acoustic resonator comprises a substrate comprising a cavity. The electrical resonator comprises a resonator stack suspended over the cavity. The resonator stack comprises a first electrode; a second electrode; a piezoelectric layer; and a temperature compensating layer comprising borosilicate glass (BSG).

To provide a vibrator made of a piezoelectric crystal having a larger electromechanical coupling coefficient and a more satisfactory frequency-temperature characteristic than those of quartz, a vibrating piece (101) is made of a Ca.sub.3Ta(Ga.sub.1-xAl.sub.x).sub.3Si.sub.2O.sub.14 single crystal (0<x1). In the single crystal, letting be a rotation angle from an X-Z plane about an X-axis serving as a rotation axis, 18x+17.524x+24.5 is set. In addition, the vibrating piece (101) is made of a Ca.sub.3Nb(Ga.sub.1-xAl.sub.x).sub.3Si.sub.2O.sub.14 single crystal (0<x1). In the single crystal of this arrangement, letting be a rotation angle from an X-Z plane about an X-axis serving as a rotation axis, 25x+23.08332x+26.167 is set.

A composite structure for an acoustic wave device comprising a heterostructure includes: a useful layer of piezoelectric material, having a first face and a second face, the first face being arranged at a first bonding interface on a support substrate having a coefficient of thermal expansion less than that of the useful layer, wherein the composite structure further comprises a functional layer, an entire surface of which is arranged at a second bonding interface on the second face of the useful layer and having a coefficient of thermal expansion less than that of the useful layer. Methods are used for producing such a composite structure.

A piezoelectric resonator that includes a single crystal Si layer, a piezoelectric thin film formed from aluminum nitride and provided on the single crystal Si layer, and first and second electrodes provided so as to sandwich the piezoelectric thin film. An element excluding nitrogen and aluminum is doped into the piezoelectric thin film formed from aluminum nitride, and a synthetic acoustic velocity of portions of the piezoelectric resonator other than the single crystal Si layer substantially coincide with the acoustic velocity of the single crystal Si layer.

A radio frequency filter and a manufacturing method thereof are provided. A radio frequency filter includes bulk acoustic wave resonators (BAWRs), the BAWRs including first BAWRs connected in series, second BAWRs connected in parallel, or a combination thereof.

A substrate for a surface acoustic wave device or bulk acoustic wave device, comprising a support substrate and an piezoelectric layer on the support substrate, wherein the support substrate comprises a semiconductor layer on a stiffening substrate having a coefficient of thermal expansion that is closer to the coefficient of thermal expansion of the material of the piezoelectric layer than that of silicon, the semiconductor layer being arranged between the piezoelectric layer and the stiffening substrate.

In examples, a device comprises a semiconductor die, a thin-film layer, and an air cavity positioned between the semiconductor die and the thin-film layer. The air cavity comprises a resonator positioned on the semiconductor die. A rib couples to a surface of the thin-film layer opposite the air cavity.

A surface acoustic wave device is disclosed. The surface acoustic wave device can include a support substrate structure, a first piezoelectric layer over the support substrate structure, a second piezoelectric layer over the first piezoelectric layer, and an interdigital transducer electrode in electrical communication with the second piezoelectric layer.

Disclosed are polarization-inverted higher-order plate-mode resonators and methods for making the same. In an aspect, a plate-mode resonator includes a first piezoelectric layer having a first crystal orientation specified by a first set of Euler angles .sub.1, .sub.1, and .sub.1, a dielectric layer disposed on a top surface of the first piezoelectric layer, a second piezoelectric layer, disposed on a top surface of the dielectric layer, having a second crystal orientation specified by a second set of Euler angles .sub.2, .sub.2, and .sub.2, wherein az is approximately equal to .sub.1, wherein a difference between .sub.2 and .sub.1 is approximately 180 degrees, and wherein .sub.2 is approximately equal to .sub.1, and a metallization structure disposed on a top surface of the second piezoelectric layer, the metallization structure comprising at least one interdigital transducer.

A method for forming an aluminum nitride layer (310, 320) comprises the provision of a substrate (100) and the forming of a patterned metal nitride layer (110). A bottom electrode metal layer (210) is formed on the exposed portions (101) of the substrate. An aluminum nitride layer portion (320) grown above the exposed portion (101) of the substrate (100) exhibits piezoelectric properties. An aluminum nitride layer portion (310) grown above the patterned metal nitride layer (110) exhibits no piezoelectric properties (310). Both aluminum nitride layer portions (320, 310) are grown simultaneously.