Measurement of Young's modulus on microfabricated structures using a surface profiler
A point-force, load-deflection method using a stylus-type surface profiler to determine the Young's moduli (E_Y) of thin-film microstructural materials is introduced. In this method both force and deflection in microstructures are measured simultaneously 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 doubly supported bridge and a bridge-slider (a beam with one fixed end and one end that can slide in a flanged housing). The influence of residual stress in the doubly supported beam is described and accounted for theoretically to interpret measurements made on low-stress silicon-nitride films. For this material E_Y 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 E_Y of 123 GPa in unannealed material that is doped heavily with phosphorous, and grown at 650°C.
Additional Information© 1990 IEEE. Date of Current Version: 06 August 2002. We thank M. Lim and W. Tang for their help with SUPERSAP simulations. We also thank K. Voros, R. Hamilton, and the staff of the Berkeley Microfabrication Laboratory for assistance in processing.
Published - TAImems90.pdf