The Influence of Adhesion Layers in the Bragg Reflector on the Electrical Characteristics of a Thin-Film BAW Solidly Mounted Resonators

Thin-film BAW resonators with a Bragg reflector are considered. The BAW resonator consists of the piezoelectric transducer based on aluminum nitride films with thin-film electrodes of aluminum and the Bragg reflector based on four pairs layers of molybdenum and silicon dioxide between which adhesion layers are placed. The analytical study of influence of adhesion layers (titanium, silicon, vanadium) in the Bragg reflector on its acoustic characteristics and electrical characteristics of BAW resonator are presented. The resonator operates at the frequency equal to 4 GHz and has the quality factor is about 370. It is shown that the adhesion layers of vanadium have the greatest effect on the shift of the resonant frequencies of the resonator and the value of the electrical impedance at the frequency of the parallel resonance.