Embodiments of this disclosure relate to reducing coupling between acoustic wave resonators. An isolation region of a substrate can be located between acoustic wave resonators. The isolation region can reduce capacitive coupling through the substrate between the acoustic wave resonators. In certain embodiments, the isolation region can be located between acoustic wave resonators of different filters to thereby increase isolation between the filters.

An acoustic wave device includes a piezoelectric material substrate, an intermediate layer on the piezoelectric material substrate and composed of one or more materials selected from the group consisting of silicon oxide, aluminum nitride and sialon, a bonding layer on the intermediate layer and composed of one or more materials selected from the group consisting of tantalum pentoxide, niobium pentoxide, titanium oxide, mullite, alumina, a high resistance silicon and hafnium oxide, a supporting body composed of a polycrystalline ceramic and bonded to the bonding layer by direct bonding, and an electrode on the piezoelectric material substrate.

Sputter depositing a metallic layer on a substrate in the fabrication of a resonator device includes providing a magnetron sputtering apparatus comprising a chamber, a substrate support disposed within the chamber, a target made from a metallic material, and a plasma generating device, wherein the substrate support and the target are separated by a distance of 10 cm or less; supporting the substrate on the substrate support; performing a DC magnetron sputtering step that comprises sputtering the metallic material from the target onto the substrate so as to form a metallic layer on the substrate, wherein during the DC magnetron sputtering step the chamber has a pressure of at least 6 mTorr of a noble gas, the target is supplied with a power having a power density of at least 6 W/cm.sup.2, and the substrate has a temperature in the range of 200-600? C.

A surface acoustic wave (SAW) resonator includes a piezoelectric layer disposed over a substrate, and a plurality of electrodes disposed over the first surface of the piezoelectric layer. A layer is disposed between the substrate and the piezoelectric layer. A surface of the layer has a smoothness sufficient to foster atomic bonding between layer and the piezoelectric layer. A plurality of features provided on a surface of the substrate reflects acoustic waves and reduce the incidence of spurious modes in the piezoelectric layer.

An acoustic resonator filter comprises a plurality of resonator structures. One or more of the plurality of resonator structures comprises a substrate having a first surface and a second surface. The resonator structure also comprises a piezoelectric layer disposed over the substrate. The acoustic wave resonator structure also comprises a layer disposed between the first surface of the substrate and the second surface of the piezoelectric layer. The layer has a first surface and a second surface. The layer and the piezoelectric layer have a combined thickness (H) selected so an anti-resonance (AR) condition exists for an undesired bulk vertical shear mode between the first surface of the piezoelectric layer and the second surface of the layer.

A surface acoustic wave (SAW) resonator includes a piezoelectric layer disposed over a substrate, and a plurality of electrodes disposed over the first surface of the piezoelectric layer. A layer is disposed between the substrate and the piezoelectric layer. A surface of the layer has a smoothness sufficient to foster atomic bonding between layer and the piezoelectric layer. A plurality of features provided on a surface of the substrate reflects acoustic waves and reduce the incidence of spurious modes in the piezoelectric layer.

An acoustic wave filter device includes a substrate, a filter disposed on the substrate, a wall member disposed on the substrate and surrounding the filter, and a cap member disposed above the wall member and, with the wall member, forming an internal space. The cap member has a curved shape and comprises a first cap member comprising a first material and a second cap member comprising a second material.

To provide a lithium niobate (LN) substrate which allows treatment conditions regarding a temperature, a time, and the like to be easily managed and in which an in-plane distribution of a volume resistance value is very small, and a method of producing the same.

A method of producing an LN substrate by using an LN single crystal grown by the Czochralski process, in which an LN single crystal having a Fe concentration of 50 mass ppm or more and 1000 mass ppm or less in the single crystal and processed into a form of a substrate is buried in an Al powder or a mixed powder of Al and Al.sub.2O.sub.3, and heat-treated at a temperature of 450 C. or more and less than 500 C., to produce a lithium niobate single crystal substrate having a volume resistivity controlled to be within a range of 110.sup.8 .Math.cm or more to 110.sup.10 .Math.cm or less.

Due to strong needs to reduce the dimensions and the cost of the RF filters and to reduce the number of filters required in an mobile handsets and wireless system covering numbers of operation bands, tunable RF filters which can cover as many bands or frequency ranges as possible are needed so that the number of filters can be reduced in the mobile handsets and wireless systems. This invention provides tunable surface acoustic wave resonators and filters utilizing semiconducting piezoelectric layers having embedded or elevated electrode doped regions. Both metallization ratio and loading mass are changed by varying a DC biasing voltage to effect a change in the resonant frequency of the tunable SAW devices.

An acoustic wave element of the present disclosures has a piezoelectric substrate and an acoustic wave resonator on a main surface of the piezoelectric substrate. The acoustic wave resonator is one being divided into a first IDT electrode and a second IDT electrode which are electrically connected to the first IDT electrode. The first IDT electrode includes a first comb-shaped electrode on the signal input side and a second comb-shaped electrode on the signal output side. The second IDT electrode includes a third comb-shaped electrode on the signal input side and a fourth comb-shaped electrode on the signal output side. The direction of arrangement of the third comb-shaped electrode and the fourth comb-shaped electrode from the third comb-shaped electrode toward the fourth comb-shaped electrode is different from the direction of arrangement from the first comb-shaped electrode toward the second comb-shaped electrode.