COMPOSITE OSCILLATOR OF PIEZOELECTRIC THIN FILM

摘要

PURPOSE:To suppress spurious caused by a high frequency by reducing the size of a piezoelectric thin film less than the area of a diaphragm thin layer part and at the same time sticking an upper electrode to the entire vibrating part of the piezoelectric thin film. CONSTITUTION:A through-hole 21 is formed by an etching solution to a silicon substrate 22 having a (100) face on its surface with a CVD film formed on the rear side of the substrate 22 used as a mask. Then a lower electrode 26 is formed on a thin film 24 provided on the substrate surface, and a thin film 25 is formed on the electrode 26. Short-circuit electrodes 27 and 28 are formed outside a vibrating part in such a form that has an area where a short-circuit part is secured. Then the film 25 is removed at the area which is not covered with the electrode. In such a constitution, the dispersed frequency correspond to a resonance frequency for the input admittance characteristics. This can suppress effectively an in-hamonic overtone.