Patent ID: 7999437

Claim:
An acoustic boundary wave device comprising: a piezoelectric body; an interdigital transducer electrode layer provided on the piezoelectric body; a pad electrode layer provided on the piezoelectric body and electrically connected to the interdigital transducer electrode layer; a first dielectric layer provided on the piezoelectric body to cover at least a part of the interdigital transducer electrode layer; and a second dielectric layer provided on the piezoelectric body to cover the first dielectric layer, and provided with an opening through which at least a part of a top face of the pad electrode layer is exposed, wherein diffusivity of a metal forming a lateral face of the pad electrode layer into the first dielectric layer is greater than that into the second dielectric layer, wherein the second dielectric layer is provided to cover lateral faces of the pad electrode layer so as to prevent the first dielectric layer from touching the lateral faces of the pad electrode layer, and wherein a nitride-oxide film is formed on the second dielectric layer.