PIEZOELECTRIC THIN FILM RESONATOR, FILTER AND ELECTRONIC DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a piezoelectric thin film resonator that has an excellent resonance characteristic and an excellent temperature characteristic of the resonance frequency and has less defect due to cracked elements, etc. SOLUTION: The piezoelectric thin film resonator includes an Si substrate 12. An AlN piezoelectric thin film 14 whose major component is a thin film AlN, a lower layer electrode 16a, an AlN piezoelectric thin film 18 whose major component is piezoelectric thin film AlN and an upper layer electrode 16b are formed on the Si substrate 12 in this order. A cavity 20 is formed to the Si substrate 12 at a part corresponding to the center part of the AlN piezoelectric thin film 14.