l MEASUREMENT OF YOUNG'S MODULUS ON MICROFABRICATED STRUCTURES USING

A point-force, load-deflection method using a stylus-type surface profiler to determine the Young's moduli (Ey) of thin-film microstructural materials is introduced. In this method both force and deflection in microstructures are measured simultane-ously by the profiler to provide a convenient and accurate means to obtain Young's modulus directly. Measurements on two types of micromechanical structures are described: a dou-bly supported bridge and a bridge-slider (a beam with one fixed end and one end which can slide in a flanged housing). The influence of residual stress in the doubly supported beam is described and accounted for theoretically to interpret measure-ments made on low-stress silicon-nitride films. For this material Ey is 373 GPa. In the bridge-slider structure, residual strain is relaxed to zero. Measurements on a polycrystalline-silicon bridge slider show a value for Ey of 123 GPa in unannealed material that is doped heavily with phosphorus, and grown at 650°C.