Estimation of the Parameters Determining Strength and Fatigue Behaviors of Arbitrarily-Shaped Polysilicon Thin Films

The fracture and fatigue behaviors of polysilicon thin film structures with arbitrary shapes were formulated by taking the stress distribution into account. The parameters appearing in both Weibull distribution and Paris’ law that describe the static strength and fatigue behaviors, respectively, are estimated using the maximum likelihood method on the basis of the results of tensile static fracture and fatigue tests performed on two types of polysilicon thin film specimens with different shapes fabricated using the same conditions. The difference between the fatigue lifetime distributions between the two types was well explained by applying the formula with a unique set of parameters. These results suggest that the fracture and fatigue behaviors of polysilicon thin films have a unique characteristics regardless of stress distributions.