SURFACE ACOUSTIC WAVE DEVICE

摘要

A surface acoustic wave device includes a piezoelectric substrate made of LiTaO₃ or LiNbO₃ having an electromechanical coefficient of about 15% or more, at least one electrode which is disposed on the piezoelectric substrate and which is a laminate film having a metal layer defining a primary metal layer primarily composed of a metal having a density higher than that of Al or an alloy of the metal and a metal layer which is laminated on the primary metal layer and which is composed of another metal, and a first SiO₂ layer which is disposed in a remaining area other than that at which the at least one electrode is located and which has a thickness approximately equivalent to that of the electrode. In the surface acoustic wave device described above, the density of the electrode is at least about 1.5 times that of the first SiO₂ layer. In addition, a second SiO₂ layer disposed so as to cover the electrode and the first SiO₂ layer and a silicon nitride compound layer disposed on the second SiO₂ layer are further provided.