Abstract: A method of manufacturing a ladder filter including first and second resonators includes: forming a piezoelectric film on an entire surface of a substrate that has respective lower electrodes of the first and second resonator formed thereon, an conductive film on the piezoelectric film, and a second film on the conductive film; forming a pattern of the second film in a prescribed region in the second area; forming a first film on an entire surface of the substrate; etching the first film, forming a pattern of the first film, the second film and the conductive film in the second area, and forming a pattern of the first film and the conductive film in the first area, to form respective upper electrodes from the conductor film; and thereafter, etching the piezoelectric film to form respective patterns of the piezoelectric film in the first and second areas, respectively.

Abstract: An acoustic wave device includes a substrate, a device chip that has a piezoelectric substrate and is flip-chip mounted on a surface of the substrate, a first insulation layer that has a dielectric constant lower than that of the piezoelectric substrate and is provided on a surface of the device chip opposite to another surface that faces the substrate, and a metal seal part that seals the device chip.

Abstract: A filter includes piezoelectric thin-film resonators having a substrate, a lower electrode supported by the substrate, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film. At least one of the piezoelectric thin-film resonators has a portion in which the upper electrode overlaps the lower electrode across the piezoelectric film. The above portion has a shape different from shapes of corresponding portions of other piezoelectric thin-film resonators, so that a spurious component in the above at least one of the piezoelectric thin-film resonators occur at a frequency different from frequencies of spurious components that occur in the other piezoelectric thin-film resonators.

Abstract: The filter includes a series arm piezoelectric thin film resonator placed in the series arm and a parallel arm piezoelectric thin film resonator placed in the parallel arm. Each of the series arm piezoelectric thin film resonator and the parallel arm piezoelectric thin film resonator includes a substrate (21), a lower electrode (22) placed on the substrate (21), a piezoelectric film (23) placed on the lower electrode (22) and a upper electrode (24) placed on the piezoelectric film (23). The ratio of the major axis length A to the minor axis length B of the resonant portion (29) in the series arm piezoelectric thin film resonator is larger than that in the parallel arm piezoelectric thin film resonator.

Abstract: A piezoelectric thin-film resonator includes: a lower electrode that is formed on a substrate; a piezoelectric film that is formed on the substrate and the lower electrode; an upper electrode that is formed on the piezoelectric film, with a portion of the piezoelectric film being interposed between the lower electrode and the upper electrode facing each other; and an additional film that is formed on the substrate on at least a part of the outer periphery of the lower electrode at the portion at which the lower electrode and the upper electrode face each other, with the additional film being laid along the lower electrode.

Abstract: A ladder filter includes a series resonator having a first film laminate in which an upper electrode and a lower electrode face each other across a piezoelectric film, and a first film provided on the first film laminate, and a parallel resonator having a second film laminate having a structure similar to that of the first film laminate, a second film provided on the second film laminate, and another first film identical to the first film.

Abstract: An acoustic wave device includes a substrate, a device chip that has a piezoelectric substrate and is flip-chip mounted on a surface of the substrate, a first insulation layer that has a dielectric constant lower than that of the piezoelectric substrate and is provided on a surface of the device chip opposite to another surface that faces the substrate, and a metal seal part that seals the device chip.

Abstract: A piezoelectric thin-film resonator includes: a lower electrode that is formed on a substrate; a piezoelectric film that is formed on the substrate and the lower electrode; an upper electrode that is formed on the piezoelectric film, with a portion of the piezoelectric film being interposed between the lower electrode and the upper electrode facing each other; and an additional film that is formed on the substrate on at least a part of the outer periphery of the lower electrode at the portion at which the lower electrode and the upper electrode face each other, with the additional film being laid along the lower electrode.

Abstract: A piezoelectric thin-film resonator includes: a lower electrode provided on a substrate; a piezoelectric film provided on the lower electrode; an upper electrode provided on the piezoelectric film so as to face the lower electrode across the piezoelectric film to thus define a resonance portion; and a weight load film provided on the upper electrode, the weight load film being provided in the resonance portion and having an area smaller than that of the resonance portion.

Abstract: A surface acoustic wave device includes a surface acoustic wave resonator. The surface acoustic wave resonator includes comb-like electrodes and reflection electrodes provided on both sides of the comb-like electrodes, and each of the reflection electrodes has at least two different pitches. It is thus possible to suppress the ripple components.

Abstract: A ladder filter includes a series resonator having a first film laminate in which an upper electrode and a lower electrode face each other across a piezoelectric film, and a first film provided on the first film laminate, and a parallel resonator having a second film laminate having a structure similar to that of the first film laminate, a second film provided on the second film laminate, and another first film identical to the first film.

Abstract: A filter includes piezoelectric thin-film resonators having a substrate, a lower electrode supported by the substrate, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film. At least one of the piezoelectric thin-film resonators has a portion in which the upper electrode overlaps the lower electrode across the piezoelectric film. The above portion has a shape different from shapes of corresponding portions of other piezoelectric thin-film resonators, so that a spurious component in the above at least one of the piezoelectric thin-film resonators occur at a frequency different from frequencies of spurious components that occur in the other piezoelectric thin-film resonators.

Abstract: A surface acoustic wave device includes a surface acoustic wave resonator. The surface acoustic wave resonator includes comb-like electrodes and reflection electrodes provided on both sides of the comb-like electrodes, and each of the reflection electrodes has at least two different pitches. It is thus possible to suppress the ripple components.