Abstract
The study investigates the vibration characteristics of the micromachined free-free beam through analytical and experimental means. In application, this study employed the resonant frequency of the micromachined free-free beam to successfully extract the elastic modulus of a thin film. As a comparison, the vibration characteristics of a micromachined cantilever have also been studied. This study demonstrates that the micromachined free-free beam is a better test key to extract the thin film elastic modulus when the wafer experiences a relatively long etching time. Moreover, the micromachined cantilever gives a lower bound and the micromachined free-free beam gives an upper bound while determining the thin film elastic modulus. Since the free-free beam is a previously fabricated and modeled micromachined structure, it can be employed as a supplement test key to the cantilever beam approach.