Aluminium nitride membranes with embedded buried idt electrodes for novel flexural plate wave devices

Novel flexural plate wave resonators based on bilayer AlN membranes were fabricated and investigated with respect to their piezoelectric response and residual film stress. In the proposed device design, the interdigital transducers (IDTs) are embedded between two AlN films. Here, chromium and aluminum were evaluated as suitable materials for IDT. Using Cr is beneficial with respect to conventional microfabrication technology, whereas Al enhances overall device performance due to enhanced conductivity. Finally, the proof-of-concept Lamb wave resonators were fabricated and characterized by means of laser Doppler vibrometry.