Piezoelectric thin film device having an additional film outside an excitation region
AssigneeNGK Insulators, Ltd.
InventorsYukihisa Osugi, Shoichiro Yamaguchi, Tomoyoshi Tai
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Abstract
An object of the present invention is to provide a piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators wherein a frequency impedance characteristic is unsusceptible to spuriousness. In a film bulk acoustic resonator, a piezoelectric thin film is supported by a support substrate via an adhesive layer. An upper electrode and a lower electrode each having a predetermined pattern are formed on upper and lower surfaces of the piezoelectric thin film. Further, on the upper surface of the piezoelectric thin film, an additional film for adding a mass to an outside of an excitation region is formed as superposed on the upper electrode.
Claims9
A piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators, the piezoelectric thin film device comprising:
- a piezoelectric thin film;
- a support for supporting said piezoelectric thin film;
- electrode films formed on both main surfaces of said piezoelectric thin film and having predetermined patterns;
- a first additional film formed outside an excitation region for exciting vibrations on at least one of the main surfaces of said piezoelectric thin film;
- and
- a second additional film having a conducting property and formed outside a region having said first additional film formed thereon on the main surface of said piezoelectric thin film having said first additional film formed thereon,
- wherein said second additional film has a thickness larger than that of said first additional film.
A piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators, the piezoelectric thin film device comprising:
- a piezoelectric thin film;
- a support for supporting said piezoelectric thin film;
- electrode films formed on both main surfaces of said piezoelectric thin film and having predetermined patterns;
- an additional film formed outside an excitation region for exciting vibrations on at least one of the main surfaces of said piezoelectric thin film,
- wherein a piezoelectric material constituting said piezoelectric thin film is lithium niobate;
- and
- said piezoelectric thin film and said support are bonded to each other via an adhesive layer.
A piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators, the piezoelectric thin film device comprising:
- a piezoelectric thin film;
- a support for supporting said piezoelectric thin film;
- electrode films formed on both main surfaces of said piezoelectric thin film and having predetermined patterns;
- and
- an additional film formed outside an excitation region for exciting vibrations on at least one of the main surfaces of said piezoelectric thin film, wherein
- a cavity which separates said excitation region from said support is formed in said support;
- a region having said additional film formed thereon extends inside a region separated from said support and enclosing said excitation region;
- and
- said additional film lowers a resonance frequency of said region having said additional film formed thereon lower than a resonance frequency of said excitation region.
A piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators, the piezoelectric thin film device comprising:
- a piezoelectric thin film;
- a support for supporting said piezoelectric thin film;
- electrode films formed on both main surfaces of said piezoelectric thin film and having predetermined patterns;
- an additional film formed outside an excitation region for exciting vibrations on at least one of the main surfaces of said piezoelectric thin film,
- wherein a mass per unit area of said additional film formed as superposed on said electrode film is not less than 0.1% and not more than 20% of a sum of a mass per unit area of said piezoelectric thin film and a mass per unit area of said electrode film in said excitation region.
Dependencies are inferred from the claim text.