Effects of nano‐grain structures and surface defects on fracture of micro‐scaled polysilicon components

This study examines a simple fracture model for microscopically heterogeneous polysilicon components when Griffith theory applicable only to homogeneous materials fails. The strength‐limiting micro/nano‐ surface defect a 0 is linked to the nano‐scaled grain size G of polysilicon and bulk fracture properties. Here the a 0 / G ratio is not large enough for polysilicon to be considered as homogeneous. Two polysilicon materials, with laminated grain structures ( G  = 125 nm) and columnar grain structures ( G  = 285 nm), have been analyzed. The simple fracture model together with a normal distribution methodology can be used to predict both the mean and 96% reliability fracture curves for the micro/nano‐crack range bridging the classic Griffith theory and the non‐linear fracture model.