Effective electromechanical coupling coefficient and quality factor control by the layer arrangement of 1.8-GHhz range film bulk acoustic wave resonators composed of ZnO, SiO/sub 2/ and Al/sub 2/O/sub 3/ thin films

Abstract

Electrical characteristics were controlled in the 1.8-GHz range film bulk acoustic wave (BAW) resonator by a layer arrangement consisting of ZnO, Al2O3 and SiO2 thin films. BAW resonators with ZnO / Al2O3 / SiO2 and ZnO / SiO2 / Al2O3 structure were designed on secondary harmonics around 1.8GHz using finite element method (FEM). Comparing the ZnO / SiO2 / Al2O3 structure with the ZnO /Al2O3 / SiO2 structure, the former BAW resonator had a larger effective electromechanical coupling coefficient (kteff 2 ), but the latter had a larger quality factor (Q