Monte-Carlo simulation of electromigration failure distributions of submicron contacts and vias: a new extrapolation methodology for reliability estimate

We have studied the electromigration failure distributions as a function of current density, and we show experimentally that the forms deviate from lognormal distributions as j approaches critical current density. The form change in failure distributions can be well described by Monte-Carlo simulation based on our physical electromigration failure model. The model predicts that median time to fail (MTF) and failure time dispersion (σ) approach infinity as j→j_c, and we show that this behavior results from a change in the functional form of failure with current density as j→j_c. We propose a new methodology for the extrapolation of contact and via electromigration data to account for the change in the form of the failure distribution