To relax stress migration, caused by strong stress applied to an Al electrode with a surface acoustic wave, when a signal of high voltage level is applied to a SAW filter, a SAW resonator, etc.
A 1st intermediate film is formed between a piezoelectric substrate and a 1st electrode film formed on its top surface. Since the 1st intermediate layer serves as the base layer of the 1st electrode film and has a large contact strength and a large elasticity constant, electrode deformation due to stress is prevented, so that the stress applied to the 1st electrode film can be reduced. Consequently, stress migration is suppressed, and electrode peeling caused at the interface part between the piezoelectric substrate and 1st electrode film can be prevented.
INOUE KAZUHIRO
HAGI TOSHIO
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