Assessment of overetch and polysilicon film properties through on-chip tests

Due to the increasing demand of miniaturization of MEMS devices, the characteristic size (e.g. the width) of some mechanical components may become comparable to that of a silicon grain. Therefore, the relevant effective mechanical properties can vary significantly from one device to another. In this work, through on-chip tests we investigate the behavior of polysilicon films using standard electrostatic actuation/sensing. The outcomes of the experimental campaign are then compared to those obtained with an analytical reduced-order model of the moving structure, and to coupled electro-mechanical simulations accounting for the polycrystalline morphology of the silicon film. These two models are adopted to bilaterally bound the experimental data up to pull-in, and to assess the scattering induced by the random orientation of the crystal lattice of each grain in slender parts of the devices.