Patent ID: 7146695

Claim:
A method for manufacturing a surface acoustic wave device including a piezoelectric substrate formed of a Y-cut piezoelectric single crystal, and at least one electrode formed on the piezoelectric substrate, the electrode including an Al electrode layer primarily composed of Al and an underlying electrode layer provided between the piezoelectric substrate and the Al electrode layer for improving the crystallinity thereof, the Al electrode layer being an oriented film formed by epitaxial growth and being a polycrystalline thin film having a twin structure in which a diffraction pattern observed in an X-ray diffraction pole figure has a plurality of symmetry centers, the method comprising steps of: preparing the piezoelectric substrate; forming the underlying electrode layer on a surface the piezoelectric substrate; forming the Al electrode layer on the underlying electrode layer; and prior to forming the underlying electrode layer, performing an etching treatment for the piezoelectric substrate to expose a crystal face on the surface of the piezoelectric substrate so that the Al electrode layer is to be formed by epitaxial growth; wherein the underlying electrode layer is made of a non-piezoelectric material.