Patent ID: 7109634

Claim:
An end surface reflection type surface acoustic wave device comprising: a piezoelectric substrate having two opposing end surfaces on which a surface acoustic wave is reflected; an electrode film made of at least one of Al and an alloy including Al as a major component on said piezoelectric substrate and which defines at least one interdigital transducer; and an insulating film arranged on said piezoelectric substrate so as to cover said electrode film; wherein a top surface of the insulating film is planarized such that irregularities between portions of the top surface of the insulating film disposed above electrode fingers of the at least one interdigital transducer and portions of the top surface of the insulating film disposed between the electrode fingers are approximately 30% or less than the film thickness of the interdigital transducer, and a ratio of the average density of said electrode film to the density of the insulating film is less than or equal to about 1.5.