Effective SAW excitation on non-piezoelectric substrate using AlScN piezoelectric thin film BAW/SAW hybrid transducer

Acoustic delay lines based on Al0.85Sc0.15N thin film hybrid transducers were investigated by finite element modeling. It was found that an acoustic impedance matching between transducer and non-piezoelectric substrate material plays a crucial role to efficiently excite a traveling surface acoustic wave (SAW) through the BAW piston motion. Test devices based on the 2.5 um thick Al0.85Sc0.15N piezoelectric film on the silicon substrate were fabricated and characterized.