A method for producing a piezoelectric device includes a laminate formation step in which a laminate including a piezoelectric thin film, a support substrate, a metal layer, and a silicon oxide film respectively stacked on both of an upper surface and a lower surface of the metal layer interposed between the piezoelectric thin film and the support substrate is formed, a semi-conducting layer formation step in which a semi-conducting layer is formed by oxidizing the metal layer, and a functional electrode formation step in which a functional electrode that is electro-mechanically coupled to the piezoelectric thin film is formed on a first principal surface of the piezoelectric thin film. The semi-conducting layer is a layer composed of a mixture of a metal constituting the metal layer and an oxide thereof, or a layer composed of a semiconductor which is an oxide of a metal constituting the metal layer.

An elastic wave device includes a LiNbO.sub.3 substrate, an IDT electrode provided on the LiNbO.sub.3 substrate, and a dielectric film that is provided on the LiNbO.sub.3 substrate so as to cover the IDT electrode and includes a projection on an upper surface of the stated dielectric film. A main mode of an elastic wave excited by the IDT electrode uses a Rayleigh wave, and a thickness of the IDT electrode is set such that a frequency at which a response by an SH wave appears is lower than a resonant frequency of the Rayleigh wave.

An elastic wave device includes a LiNbO.sub.3 substrate, an IDT electrode provided on the LiNbO.sub.3 substrate, and a dielectric film that is provided on the LiNbO.sub.3 substrate so as to cover the IDT electrode and includes a projection on an upper surface of the stated dielectric film. A main mode of an elastic wave excited by the IDT electrode uses a Rayleigh wave, and a thickness of the IDT electrode is set such that a frequency at which a response by an SH wave appears is lower than a resonant frequency of the Rayleigh wave.

An acoustic wave device includes a piezoelectric substrate, an IDT electrode provided on the piezoelectric substrate, a support provided on the piezoelectric substrate so as to surround the IDT electrode, and a cover provided on the support. The support has a larger thermal expansion coefficient than the piezoelectric substrate. The IDT electrode is provided in a hollow space that is surrounded by the piezoelectric substrate, the support, and the cover. The support includes an inner surface on a side of the hollow space, and an outer surface on a side opposite to the inner surface, and the support includes a recess provided in at least one of the inner and outer surfaces.

An acoustic wave device includes a piezoelectric substrate, an IDT electrode provided on the piezoelectric substrate, a support provided on the piezoelectric substrate so as to surround the IDT electrode, and a cover provided on the support. The support has a larger thermal expansion coefficient than the piezoelectric substrate. The IDT electrode is provided in a hollow space that is surrounded by the piezoelectric substrate, the support, and the cover. The support includes an inner surface on a side of the hollow space, and an outer surface on a side opposite to the inner surface, and the support includes a recess provided in at least one of the inner and outer surfaces.

A method of reducing non-uniformity in the resonance frequencies of a surface acoustic wave (SAW) device, the SAW device comprising a silicon oxide layer comprising an oxide of silicon deposited over interdigital transducers on a piezoelectric substrate by reactive sputtering. The method comprises positioning a piezoelectric substrate having interdigital transducers on a substrate support, then depositing a silicon oxide layer comprising an oxide of silicon over the piezoelectric substrate and the interdigital transducers to form a SAW device. The substrate support is positioned relative to a sputtering target so that the silicon oxide layer of the SAW device has an arithmetic mean surface roughness (R.sub.a) of 11 angstroms or less.

A method of reducing non-uniformity in the resonance frequencies of a surface acoustic wave (SAW) device, the SAW device comprising a silicon oxide layer comprising an oxide of silicon deposited over interdigital transducers on a piezoelectric substrate by reactive sputtering. The method comprises positioning a piezoelectric substrate having interdigital transducers on a substrate support, then depositing a silicon oxide layer comprising an oxide of silicon over the piezoelectric substrate and the interdigital transducers to form a SAW device. The substrate support is positioned relative to a sputtering target so that the silicon oxide layer of the SAW device has an arithmetic mean surface roughness (R.sub.a) of 11 angstroms or less.

A surface acoustic wave resonator device and method for manufacturing the same and filter, the surface acoustic wave resonator device includes: a piezoelectric substrate; an interdigital transducer, disposed on the piezoelectric substrate and comprising a first interdigital electrode structure and a second interdigital electrode structure, wherein each interdigital electrode structure comprises an interdigital electrode and an interdigital electrode lead-out part connected with each other; and a first temperature compensation layer, disposed on the piezoelectric substrate and comprising a body part and a protruding part, wherein the body part covers the interdigital transducer, the protruding part is protruded from the body part towards the piezoelectric substrate in a third direction perpendicular to a main surface of the piezoelectric substrate, and is surrounded by the piezoelectric substrate in a direction parallel to the main surface of the piezoelectric substrate.

A surface acoustic wave resonator device and method for manufacturing the same and filter, the surface acoustic wave resonator device includes: a piezoelectric substrate; an interdigital transducer, disposed on the piezoelectric substrate and comprising a first interdigital electrode structure and a second interdigital electrode structure, wherein each interdigital electrode structure comprises an interdigital electrode and an interdigital electrode lead-out part connected with each other; and a first temperature compensation layer, disposed on the piezoelectric substrate and comprising a body part and a protruding part, wherein the body part covers the interdigital transducer, the protruding part is protruded from the body part towards the piezoelectric substrate in a third direction perpendicular to a main surface of the piezoelectric substrate, and is surrounded by the piezoelectric substrate in a direction parallel to the main surface of the piezoelectric substrate.

Surface acoustic wave (SAW) filter packages employing an enhanced thermally conductive cavity frame for heat dissipation, and related fabrication methods are disclosed. The SAW filter package also includes a cavity frame comprising a perimeter structure and a cavity inside the perimeter structure coupled to a substrate of a piezoelectric material that contains interdigital transducers (IDTs). A cap substrate is disposed on the perimeter structure of the cavity frame to enclose an air cavity inside the perimeter structure between a substrate and the cap substrate. In exemplary aspects, to effectively dissipate heat generated in the SAW filter package to maintain the desired performance of the SAW filter, the cavity frame is comprised of a material that has an enhanced thermal conductivity. The heat generated in the SAW filter package can more effectively be dissipated, particularly at edges and corners of the cavity frame where hot spots can particularly occur.