The characterization of dielectric and piezoelectric thin films by surface acoustic wave propagation techniques

Thin films are at the very heart of surface acoustic wave(SAW) device technology. Thin film metal patterns on piezoelectric crystals generate, detect, and manipulate SAW waveforms. Dielectric films have been used to enhance the propagation properties of SAW devices. Piezoelectric films extend SAW device development to amorphous and nonpiezoelectric substrates. This paper describes the results of experimental work on the characterization of dielectric and piezoelectric thin films using SAW interdigital electrode patterns to determine acoustic properties useful for SAW device development. The film/substrate combinations discussed are:(1)plasma enhanced chemical vapor deposited silicon nitride, silicon carbide, and silicon-oxy-nitride on gallium arsenide substrates, (2)sputtered glass on 41 degrees and 64 degrees Y-X lithium niobate and 36 degrees Y-X lithium tantalate, (3)zinc oxide on gallium arsenide, and (4) aluminum nitride on silicon.