Tensile stress determination in silicon nitride membrane by AFM characterization

A silicon nitride layer deposited on silicon presents strong tensile residual stress. This stress may lead to cracks and failure for released membrane applications. The article demonstrates a novel way to determine the residual stress of a low stress silicon nitride membrane by non destructive method thanks to AFM (atomic force microscopy) characterization. Force imaging in tapping mode and resonance frequency variation images enable the extraction of the variation of stiffness directly on the membrane by modelling the tip-surface interaction. Then, the relative tensile stress associated with the stiffness in the membrane is extracted using two different analytical models and compared with a finite element simulation.