Electromigration is re-emerging as a significant problem in modern integrated circuits (IC). Especially in power-grids, due to shrinking wire widths and increasing current densities, there is little or no margin left between the predicted EM stress and that allowed by the EM design rules. Statistical Electromigration Budgeting estimates the reliability of the grid by considering it as a series system. However, a power grid with its many parallel paths has much inherent redundancy. In this work, we propose a new model to estimate the MTF and reliability of the power grid under the influence of EM, which accounts for these redundancies. To implement the mesh model, we also develop a framework to estimate the change in statistics of an interconnect as its effective-EM current varies. The results indicate that the series model gives a pessimistic estimate of power grid MTF by a factor of 3-4.

Electromigration is re-emerging as a significant problem in modern integrated circuits (IC). Especially in power-grids, due to shrinking wire widths and increasing current densities, there is little or no margin left between the predicted EM stress and that allowed by the EM design rules. Statistical Electromigration Budgeting estimates the reliability of the grid by considering it as a series system. However, a power grid with its many parallel paths has much inherent redundancy. In this work, we propose a new model to estimate the MTF and reliability of the power grid under the influence of EM, which accounts for these redundancies. To implement the mesh model, we also develop a framework to estimate the change in statistics of an interconnect as its effective-EM current varies. The results indicate that the series model gives a pessimistic estimate of power grid MTF by a factor of 3-4.