The effect of water on the mechanical properties of native oxide coated silicon structure in MEMS

•Effects of water on the tensile properties of Si were examined by MD simulations.•The fracture strength of the Si in water is lower than the result in dry environment.•The influence of water on the tension properties of Si-film is extremely rapid.•The cracks initiate from the Si rather than from the surface oxide layer. The influence of a humid environment on the reliability of microelectromechanical systems (MEMS) needs to be considered in applications such as chemical and biological sensors. We have examined the effects of water on the mechanical properties of silicon thin-films covered by a surface native oxide layer using reactive molecular dynamics simulations. The results of quasi-static tensions show that the silicon fracture strength of 11.2GPa in the presence of water is lower than the fracture strength of 16.3GPa in dry environment. Moreover, the effect of water on the tension properties of silicon is extremely rapid (within 2ns). In both dry and liquid water environments, the cracks initiate from the silicon structure rather than from the surface oxide layer.