SURFACE ACOUSTIC WAVE ELEMENT AND ITS MANUFACTURE

摘要

PROBLEM TO BE SOLVED: To provide a small-sized surface acoustic wave element at a low cost and its manufacture. SOLUTION: A gold electrode 32 is formed on a piezoelectric substrate 31 and then a silicon nitride 33 is deposited on the entire face and an opening 38 to expose a bonding pad 37 is formed. Then a zinc oxide film is formed selectively on a part where a surface acoustic wave is stimulated and propagated. Then a poly silicon cover layer 35 is formed on the entire face and an opening 39 to expose a zinc oxide film is formed. The zinc oxide film is selectively removed via the opening 39 by the wet etching to form a vibrating space 36. The silicon nitride 33 with a thickness hardly disturbing the vibration and stimulation of the surface acoustic wave is formed on the part where a surface acoustic wave is stimulated and propagated and a cover layer 35 made of a poly silicon having the vibration space is formed on it, then a ceramic package or the like is not required to attain miniaturization and the element is formed in a state of a wafer before chip processing, then man-hour is reduced and the element is manufactured at a low cost.