FILM BULK ACOUSTIC RESONATOR, PIEZOELECTRIC THIN FILM DEVICE AND METHOD FOR MANUFACTURING THE PIEZOELECTRIC THIN FILM DEVICE

摘要

A film bulk acoustic resonator (10) includes substrates (11, 12) having an oscillation space (20), and a piezoelectric laminated structure (14) arranged to face the oscillation space (20). The piezoelectric laminated structure (14) is provided with at least a lower electrode (15), a piezoelectric thin film (16) and an upper electrode (17), which are arranged in sequence from the side close to the oscillation space (20). A lower insulating layer (13) is formed in contact with the lower surface of the lower electrode (15), and an upper insulating layer (23) is formed in contact with the lower surface of the upper electrode (17). A side spacer (26) made of a material different from that of the electrode is arranged on the outer circumference of the lower electrode (15) and the upper electrode (17). A step on an interface between the side spacer (26) and the electrodes (15, 17) is less than 25nm. The piezoelectric thin film (16) is composed of aluminum nitride. The acoustic impedance of the side spacer (26) is larger than the acoustic impedances of the electrodes (15, 17).