An acoustic wave device includes a support substrate, a piezoelectric body, an acoustic layer laminate, first and second electrodes, and a lead-out electrode. The first electrode is on a first main surface of the piezoelectric body, the second electrode is on a second main surface of the piezoelectric body, the lead-out electrode is on the first main surface or the second main surface of the piezoelectric body, the lead-out electrode is electrically connected to the first electrode or the second electrode, side surface grooves extend from the first main surface side of the piezoelectric body, and the side surface grooves are provided in at least a portion of a remaining portion excluding a portion provided with the lead-out electrode from a region in an outer side portion of at least one of the first electrode and the second electrode.

An acoustic wave device includes: a piezoelectric substrate; an IDT that is formed on the piezoelectric substrate and includes a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes including an grating electrode that excites an acoustic wave and a bus bar to which the grating electrode is connected; and reforming regions that are located only inside the piezoelectric substrate and arranged at intervals under the IDT, and in which a material of the piezoelectric substrate is reformed.

A composite substrate according to the present invention includes a support substrate having a diameter of 2 inches or more, and a piezoelectric substrate having a thickness of 20 m or less and bonded to the support substrate to transmit light. The piezoelectric substrate has a thickness distribution shaped like a fringe. A waveform having an amplitude within a range of 5 to 100 nm in a thickness direction and a pitch within a range of 0.5 to 20 mm in a width direction appears in the thickness distribution of the piezoelectric substrate in a cross section of the composite substrate taken along a line orthogonal to the fringe, and the pitch of the waveform correlates with a width of the fringe. In the piezoelectric substrate, the fringe may include either parallel fringes or spiral or concentric fringes.

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.

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 piezoelectric layer reflects acoustic waves and reduces the incidence of spurious modes in the piezoelectric 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.

A surface acoustic wave device comprising a base substrate, a piezoelectric layer and an electrode layer in between the piezoelectric layer and the base substrate, a comb electrode formed on the piezoelectric layer comprising a plurality of electrode means with a pitch p, defined asp=A, with A being the wavelength of the standing acoustic wave generated by applying opposite potentials to the electrode layer and comb electrode, wherein the piezoelectric layer comprises at least one region located in between the electrode means, in which at least one physical parameter is different compared to the region underneath the electrode means or fingers. A method of fabrication for such surface acoustic wave device is also disclosed. The physical parameter may be thickness, elasticity, doping concentration of Ti or number of protons obtained by proton exchange.

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.

A method of forming an acoustic wave device is disclosed. The method can include providing a structure having a support substrate that includes a first substrate portion, a second substrate portion, and a third substrate portion between the first portion and the second portion, a piezoelectric layer that includes a first portion over the first substrate portion and a second portion over the second substrate portion, a first interdigital transducer electrode on the first portion of the piezoelectric layer, and a second interdigital transducer electrode on the second portion of the piezoelectric layer. the method can also include etching at least a portion of the piezoelectric layer such that a region over the third substrate portion is free from the piezoelectric layer.

An acoustic wave device has a multilayer piezoelectric substrate (MPS) structure and a multilayer interdigital transducer electrode (IDT). The multilayer piezoelectric substrate includes a piezoelectric layer over a support substrate. An additional (functional) layer can optionally be interposed between the piezoelectric layer and the support substrate, which can facilitate bonding between these layers and provide temperature compensation. The multilayer IDT is disposed over the piezoelectric layer and includes a first layer of a first material with higher density and a second layer of a different material with lower density. The interdigital transducer electrode also includes (mass loading) strips disposed over (e.g., adjacent, in contact with) the second layer, which advantageously facilitate suppression of transverse mode.