Patent ID: 8829762

Claim:
A surface acoustic wave device comprising: a piezoelectric monocrystal substrate having any cut angle, and an interdigital electrode configured of a base electrode layer formed on the piezoelectric monocrystal substrate, the base electrode layer being made of a conductive material, and an aluminum-containing main electrode layer formed on the base electrode layer by epitaxial growth, wherein: the interdigital electrode has an upper layer formed on the main electrode layer, the upper layer being made of a conductive material that is different from materials for the main electrode layer and the base electrode layer and has a larger specific gravity than aluminum, the interdigital electrode is composed of a three-layer structure being configured with the base electrode layer, the main electrode layer, and the upper layer, the base electrode layer comprises a titanium nitride layer formed on the piezoelectric monocrystal substrate and a titanium layer formed further on the said titanium nitride layer, on which the main electrode layer is formed by epitaxial growth, the upper layer, which is the top layer of the interdigital electrode and located on the main electrode layer, is made of tungsten or tantalum, and the interdigital electrode is surrounded by silicon dioxide.