An acoustic wave filter includes series resonators and parallel resonators that have a piezoelectric film on an identical substrate and have a lower electrode and an upper electrode, wherein: one of the series resonators and the parallel resonators have a temperature compensation film on a face of the lower electrode or the upper electrode that is opposite to the piezoelectric film in a resonance region, the compensation film having an elastic constant of a temperature coefficient of which sign is opposite to a sign of a temperature coefficient of an elastic constant of the piezoelectric film; and the other have an added film on the same side as the temperature compensation film on the lower electrode side or the upper electrode side compared to the piezoelectric film in the resonance region in the one of the series resonators and the parallel resonators.

A resonator element includes: a base portion including a first end surface that faces a first direction and a second end surface that faces a direction opposite to the first direction, a first vibrating arm that is provided integrally with the base portion and is connected to the first end surface; and a second vibrating arm that is provided integrally with the base portion along the first vibrating arm and is connected to the first end surface. When the shortest distance between the first end surface and the second end surface is Wb and an effective width between the shortest distance Wb and the base portion is We, 0.81Wb/We1.70 is satisfied.

An acoustic wave filter includes series resonators and parallel resonators that have a piezoelectric film on an identical substrate and have a lower electrode and an upper electrode, wherein: one of the series resonators and the parallel resonators have a temperature compensation film on a face of the lower electrode or the upper electrode that is opposite to the piezoelectric film in a resonance region, the compensation film having an elastic constant of a temperature coefficient of which sign is opposite to a sign of a temperature coefficient of an elastic constant of the piezoelectric film; and the other have an added film on the same side as the temperature compensation film on the lower electrode side or the upper electrode side compared to the piezoelectric film in the resonance region in the one of the series resonators and the parallel resonators.

A resonator element includes: a base portion including a first end surface that faces a first direction and a second end surface that faces a direction opposite to the first direction, a first vibrating arm that is provided integrally with the base portion and is connected to the first end surface; and a second vibrating arm that is provided integrally with the base portion along the first vibrating arm and is connected to the first end surface. When the shortest distance between the first end surface and the second end surface is Wb and an effective width between the shortest distance Wb and the base portion is We, 0.81Wb/We1.70 is satisfied.

A frequency adjustment method is provided for a piezoelectric resonator including a first vibrator, a second vibrator, a third vibrator, and a supporting portion. The second and the third vibrators connect to ends positioned along a vibration direction of a width-longitudinal mode in the first vibrator. The supporting portion is connected to two ends positioned along a vibration direction of the length-longitudinal mode in the first vibrator. The method includes: setting the second vibrator to a first region, a second region, and a third region along the vibration direction of the width-longitudinal mode; setting the third vibrator to a first region, a second region, and a third region along the vibration direction of the width-longitudinal mode; and performing the frequency adjustment by reducing or adding mass of at least one of the first region and the third region in each of the second vibrator and the third vibrator.

A method of manufacturing an ultrasound transducer is provided. The ultrasound transducer is activated and the activity across the transducer is measured to determine whether the activity at any area does not meet an acceptance criteria. The transducer is then modified so that the area meets the acceptance criteria. The transducer may be modified with a laser which removes material from the area which does not meet the acceptance criteria.

An acoustic resonator device includes a temperature compensation structure disposed beneath the first electrode and above the substrate.

A piezoelectric device that prevents defects due to pyroelectric charge without limiting how the piezoelectric device can be used includes a first metal layer located on a bonding surface of a piezoelectric single crystal substrate. A second metal layer is located on a bonding surface of a support substrate. The first and second metal layers are overlaid on each other to define a metal bonded layer. Subsequently, by oxidizing the metal bonded layer, a semi-conducting layer is formed.

In examples, a device comprises a semiconductor die, a thin-film layer, and an air cavity positioned between the semiconductor die and the thin-film layer. The air cavity comprises a resonator positioned on the semiconductor die. A rib couples to a surface of the thin-film layer opposite the air cavity.

A bulk acoustic wave resonator, a method for manufacturing a bulk acoustic wave resonator and an electronic device are provided, and belongs to the field of communication technology. The bulk acoustic wave resonator includes: a first base substrate, a first electrode, a piezoelectric layer, and a second electrode; the first electrode is on the first base substrate; the piezoelectric layer is on a side of the first electrode away from the first base substrate; the second electrode is on a side of the piezoelectric layer away from the first electrode; a functional layer is formed on a side of the piezoelectric layer close to the first base substrate and/or on a side of the piezoelectric layer away from the first base substrate; the functional layer is made of a conductive material, and the functional layer is configured to suppress a temperature drift of the bulk acoustic wave resonator.