SURFACE ACOUSTIC WAVE DEVICE AND PRODUCTION METHOD THEREOF

摘要

A surface acoustic wave device for processing signals of high frequency as high as 1 GHz or above by using surface acoustic waves, which propagate while radiating bulk waves such as a longitudinal wave type leaky wave perpendicular to a piezoelectric substrate, is given a structure of an IDT having a sufficiently small electrical resistance without increasing a propagation loss. The device includes a piezoelectric substrate (10) and an electrode comprising a conductive film (12) for exciting, receiving, reflecting and propagating an elastic surface wave on the piezoelectric substrate (10), and the surface acoustic wave propagates along the surface of the piezoelectric substrate (10) while radiating at least one transverse wave component of a bulk wave perpendicular to the surface of the piezoelectric substrate (10). The thickness of an insulating film of a first region is different from the thickness of an insulating film (18) of a second region so that the acoustic impedance to the surface acoustic wave becomes substantially equal both in the first region where the conductive film (12) inside the electrode is disposed and the second region where the conductive film inside the electrode is not disposed.