Patent ID: 7518291

Claim:
A piezoelectric device including a base substrate, a resonator element with a frame layered over and fixed to the base substrate, and a lid layered over and fixed to the resonator element with a frame, wherein: the base substrate, the resonator element with a frame, and the lid are all formed from a same material or are formed from materials having very similar coefficients of linear expansion; the resonator element with a frame includes a resonator element main body that is a piezoelectric resonator element section and a frame section formed so as to surround a periphery of the resonator element main body; each bonding surface bonding the base substrate, the resonator element with a frame, and the lid is bonded by surface activation bonding and hermetically sealed; an electrode for driving formed on the resonator element main body is routed to the frame section as an extraction electrode, and the extraction electrode of the frame section is electrically connected to a mounting electrode, provided on the base substrate and serving as an external terminal, by bonding, via a conductive pattern formed on a bonding surface of the base substrate; wherein the resonator element main body that is the piezoelectric resonator element section includes a base section extending from an inner side of an edge forming the frame section, within the frame section, further comprising; a plurality of resonating arms extending from the base section with; long grooves formed along a length direction of a main surface of a resonating arm and including a driving electrode therewithin provided on each of the plurality of resonating arms, wherein wherein a width dimension of each resonating arm has a narrowing width portion in which the width gradually narrows from a base section side toward a tip of a resonating arm and a changing point P of width in which the width dimension extends toward the tip side by an equal dimension or begins to increase between the changing point and the tip of the resonating arm, and with the changing point P positioned closer to the tip of the resonating arm than to a tip of a long groove.