SURFACE ACOUSTIC WAVE ELEMENT, FILTERING APPARATUS AND MANUFACTURING METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a surface acoustic wave element, a filtering apparatus and a manufacturing method thereof in which a comparatively great electromechanical coupling coefficient is provided and temperature stability is improved without deteriorating filter characteristics. SOLUTION: A piezoelectric substrate 2 formed from lithium tantalate (LT) or lithium niobate (LN) and a substrate 1 formed from silicon (Si) of which a thermal expansion coefficient is lower than that of the piezoelectric substrate 2 are coupled by direct bonding. On the substrate 1, an area positioned just under a tandem electrode 12 (and a reflection electrode 13) formed on the piezoelectric substrate 2 is etched by using an RIE apparatus or the like to form a cavity 1a. Further, a coarse surface 2a or a sound absorption layer is formed on a rear surface of the piezoelectric substrate 2 exposed by the cavity 1a. COPYRIGHT: (C)2004,JPO