PIEZOELECTRIC RESONATOR AND PIEZOELECTRIC FILTER

摘要

PROBLEM TO BE SOLVED: To provide a piezoelectric resonator that can satisfy countermeasures for leakage in vibration and spurious vibration and also the yield at the same time. SOLUTION: The piezoelectric resonator 10 includes a 100} Si substrate 12. A diaphragm section 16 is formed to the center of the 100} Si substrate 12 by a dielectric layer 14a made of SiO2. A lower electrode 18a, a piezoelectric layer 20 and an upper electrode 18b are formed on the dielectric layer 14a as a vibration means in a thickness longitudinal oscillation or thickness shear oscillation n-order mode. The opposed parts of the lower electrode 18a and the upper electrode 18b are formed to be a square including a circle with a radius of a multiple of 20/n of a thickness (t) of the opposed parts of the lower electrode 18a and the upper electrode 18b or over. The shortest distance (x) from the end of the opposed parts of the lower electrode 18a and the upper electrode 18b to the end of the 100} Si substrate 12 is 2t/n<=x<=10t.