ELASTIC SURFACE WAVE DEVICE, MODULE DEVICE, OSCILLATION CIRCUIT, AND ELASTIC SURFACE WAVE DEVICE FABRICATION METHOD

摘要

It is possible to provide a small-size SH wave-type SAW device as a surface wave device using a crystal substrate having a large Q value and an excellent frequency aging characteristic. The elastic surface wave device includes a piezoelectric substrate and an IDT electrode formed of an alloy containing Al as a main component on the piezoelectric substrate and uses an excitation wave as the SH wave. The piezoelectric substrate is a flat quartz plate in which the cut angle ? of the rotary Y-cut quartz substrate is set in a range -64.0 degrees < ? < -49.3 degrees and the elastic surface wave propagation direction is set to 90 degrees ± 5 degrees with respect to the crystal X axis. When the oscillating elastic surface wave has a wavelength ?, the electrode film thickness H/? standardized by the wavelength of the IDT electrode is set to 0.04 < H/? < 0.12. The quartz substrate is etched with a thickness not smaller than 0.002 µm. Thus, it is possible to obtain an SH wave-type elastic surface wave device.