Measurement of Material Properties for Polysilicon Thin Films by an Electrostatic Force Method

This paper presentsa novel in-situ test structure for determining Young's modulus and Poisson's ratio of polysilicon thin films, based on electrostatic driving mechanism. The test structure manufactured with polysilicon surface processes, include two parts, one is used for the measurement of Young's modulus, and the other is used for the measurement of Poisson's ratio. By monitoring the deflection of polysilicon beams under the electrostatic force, the Young's modulus and Poisson's ratio can be obtained analytically. Validation and accuracy of the extracting method have been verified by FEM simulation andexperiments. The main advantage of this approach lies in the avoidance of the pull-in phenomena. The test structure can be widely used in MEMS process monitoring and the in-situ extraction of material properties.