Patent ID: 6888424

Claim:
A piezoelectric resonator comprising: a substrate; a vibration unit disposed on the substrate and having a structure in which at least one pair of an upper electrode and a lower electrode are opposed to each other, the upper and lower electrodes sandwiching the upper and lower surfaces of an internal thin-film portion including at least one layer of a piezoelectric thin-film; and an external thin-film portion provided under the lower electrode and including at least one layer of one of a piezoelectric thin-film and a dielectric thin-film; wherein the vibration unit is vibrated in an n-th harmonic, where n is an integer of 2 or greater, the upper electrode and the lower electrode are located substantially in the positions of the loops of the n-th harmonic; wherein the external thin-film portion includes an SiQ 2 thin-film as a major component; the internal thin-film portion includes AIN as a major component; and nodes of the n-th harmonic exist in the internal and external thin-film portions.