Comparative Study of Acoustic Wave Devices Using Thin Piezoelectric Plates in the 3-5-GHz Range

This paper investigates the applicability of acoustic wave devices using an interdigital transducer placed on a thin piezoelectric crystal plate to the 3-5-GHz range, where significant performance degradation was expected in surface acoustic wave (SAW) devices. Three types of the SAW-like devices were fabricated by using a KrF stepper/scanner, and their performances are compared from various aspects: 1) a 3.5-GHz resonator using a rotated Y-cut LiTaO3 plate attached on a Si substrate; 2) a 5-GHz resonator using a X-cut LiNbO3 plate on a Si substrate; and 3) a 5.4-GHz A(1) Lamb mode resonator on a free-standing Z-cut LiNbO3 plate. It is revealed that these devices offer excellent performances even in the 3-5-GHz range.