SURFACE ACOUSTIC WAVE DEVICE AND METHOD OF PRODUCING THE SAME

摘要

A conventional surface acoustic wave device is constituted of a piezoelectric substrate, an electrode film formed on the piezoelectric substrate and divided into electrode fingers, a bus bar connecting the electrode fingers in common, and electrode pads connected to the bus bar. When such a device is used in a high-frequency band, the thickness of the electrode film is too small and the width of the electrodes is also too small, causing the problem of poor mechanical strength. The electrode film of the present invention has at least two layers, for example, a layer containing Ta and Al and a layer containing Al or an Al-based alloy and formed thereon. The ratio of Ta to Al is such that Ta accounts for 39 to 75 atomic percent to enhance the orientation of Al or its alloy and, hence, to increase the strength of the electrode film.