THIN-FILMS FOR SAW DEVICES

Abstract

Thin-films play a significant role in surface acoustic wave (SAW) technology. Thin metal films are essential for the generation and detection of SAWs on piezoelectric subtrates, can provide for directional control, influence the velocity and propagation loss, and can be configured to produce a wide variety of time and frequency signal processing functions for electronic systems. Dielectric films have been used to selectively modify the propagation properties of surface waves, protect the surfce, and improve the coupling efficiency and temperature characteristics of SAW devices. Piezoelectric films have extended SAW device developments to amorphous and nonpiezoelectric crystals for enhanced frequency and loss performance, lower cost, and microelectronic integration. Semiconductor, optical, and magnetic films have shown promise for active acoustoelectronic, acoustooptic, and magnetoacoustic devices. Chemically sensitive films are the basis for SAW sensor developments. Active research continues today in improving the properties and utilization of thin films on SAW substrates through advances in processing and characterization.