A BAW resonator with an improved lateral energy confinement is provided. The resonator has a bottom electrode in a bottom electrode layer, a top electrode in a top electrode layer and a piezoelectric layer between the bottom electrode layer and the top electrode layer. The piezoelectric layer comprises piezoelectric materials of different piezoelectric polarities.

Described herein is a method of bonding a piezoelectric substrate to a support substrate to form a composite substrate. The piezoelectric substrate has one surface which is positively polarized, and a second surface which is negatively polarized. The method described herein includes the steps of bonding the positively polarized surface of the piezoelectric substrate to one surface of the support substrate by a direct bonding method.

A frequency adjustment method of a vibrator element includes preparing a vibrator element that has a vibrating arm, a first weight placed on one principal surface of the vibrating arm, and a second weight placed on the other principal surface of the vibrating arm, in which the first weight has a non-overlapping region which does not overlap the second weight in a plan view in a normal direction of the principal surface, preparing a substrate including a wiring portion, and fixing the vibrator element to the substrate by causing the other principal surface side of the vibrator element to face the substrate side, and irradiating the non-overlapping region of the first weight with an energy ray from one principal surface side, removing a portion of the non-overlapping region of the first weight, and adjusting a resonance frequency of the vibrating arm.

An electronic device and a method of forming the same are disclosed. An emitter resonator and a reception cap cavity are formed on and in a first wafer, and an emitter cap cavity and a reception resonator are formed in and on a second wafer. After bonding together the first and second wafers, an emitter filter is formed in an emission region, and a reception filter is formed in a receiving region. The method provided in the present invention not only can simplify the fabrication process of the device and improve its accuracy and stability, but also facilitates integration of the emitter and receives filters in a same chip, which results in a higher degree of integration of the device and a more compact package size thereof.

An object is to provide a frequency adjustment method for a piezoelectric resonator device that is applicable to a microminiaturized device and that can adjust the frequency without deteriorating the accuracy of frequency adjustment. A frequency adjustment method for a tuning-fork quartz resonator is applicable to a tuning-fork quartz resonator that includes a tuning-fork quartz resonator piece having a pair of resonator arms 31, 32 and metallic adjustment films W formed on the resonator arms. The frequency adjustment method adjusts the frequency by reduction of a mass of the metallic adjustment films W. The frequency adjustment method includes: a rough adjustment step for roughly adjusting the frequency by partially thinning or removing the metallic adjustment films W; and a fine adjustment step for finely adjusting the frequency by at least partially thinning or removing products W1, W2 derived from the metallic adjustment film W during the rough adjustment step.

A BAW resonator with an improved lateral energy confinement is provided. The resonator has a bottom electrode in a bottom electrode layer, a top electrode in a top electrode layer and a piezoelectric layer between the bottom electrode layer and the top electrode layer. The piezoelectric layer comprises piezoelectric materials of different piezoelectric polarities.

An object is to provide a frequency adjustment method for a piezoelectric resonator device that is applicable to a microminiaturized device and that can adjust the frequency without deteriorating the accuracy of frequency adjustment. A frequency adjustment method for a tuning-fork quartz resonator is applicable to a tuning-fork quartz resonator that includes a tuning-fork quartz resonator piece having a pair of resonator arms 31, 32 and metallic adjustment films W formed on the resonator arms. The frequency adjustment method adjusts the frequency by reduction of a mass of the metallic adjustment films W. The frequency adjustment method includes: a rough adjustment step for roughly adjusting the frequency by partially thinning or removing the metallic adjustment films W; and a fine adjustment step for finely adjusting the frequency by at least partially thinning or removing products W1, W2 derived from the metallic adjustment film W during the rough adjustment step.

In the composite substrate 10, the piezoelectric substrate 12 and the support substrate 14 are bonded by direct bonding using an ion beam. One surface of the piezoelectric substrate 12 is a negatively-polarized surface 12a and another surface of the piezoelectric substrate 12 is a positively-polarized surface 12b. An etching rate at which the negatively-polarized surface 12a is etched with a strong acid may be higher than an etching rate at which the positively-polarized surface 12b is etched with the strong acid. The positively-polarized surface 12b of the piezoelectric substrate 12 is directly bonded to the support substrate 14. The negatively-polarized surface 12a of the piezoelectric substrate 12 may be etched with the strong acid.

In the composite substrate, the piezoelectric substrate and the support substrate are bonded by direct bonding using an ion beam. One surface of the piezoelectric substrate is a negatively-polarized surface and another surface of the piezoelectric substrate is a positively-polarized surface. An etching rate at which the negatively-polarized surface is etched with a strong acid may be higher than an etching rate at which the positively-polarized surface is etched with the strong acid. The positively-polarized surface of the piezoelectric substrate is directly bonded to the support substrate. The negatively-polarized surface of the piezoelectric substrate may be etched with the strong acid.

A frequency adjustment method of a vibrator element includes preparing a vibrator element that has a vibrating arm, a first weight placed on one principal surface of the vibrating arm, and a second weight placed on the other principal surface of the vibrating arm, in which the first weight has a non-overlapping region which does not overlap the second weight in a plan view in a normal direction of the principal surface, preparing a substrate including a wiring portion, and fixing the vibrator element to the substrate by causing the other principal surface side of the vibrator element to face the substrate side, and irradiating the non-overlapping region of the first weight with an energy ray from one principal surface side, removing a portion of the non-overlapping region of the first weight, and adjusting a resonance frequency of the vibrating arm.