Influence of Spacer in Acoustic Reflector on Parameters of Microelectronic BAW Resonators

Microelectronic BAW resonators with a symmetric and asymmetric Bragg reflector based on molybdenum and aluminum films and a piezoelectric film of aluminum nitride are considered. It is shown that the presences of a spacer in an asymmetric reflector allows efficient reflection of longitudinal and shear acoustic waves. The analytical studies of the acoustic characteristics of reflectors and parameters of resonator based on them are presented. The resonator operates at a resonant frequency of 5 GHz and has a quality factor of about 1000. It is established that the use of an asymmetric reflector in the resonator leads to a shift in the frequencies of series and parallel resonances to the high frequency region and the quality factor decreases by 2 %.