A Layout Sensitivity Model for Estimating Electromigration-vulnerable Narrow Interconnects

During the back-end manufacturing process of IC, intervention of spot defects induces extra and missing material of interconnects causing circuit failures. In this paper, a new type of spot defects called interconnect “narrowing defect” is defined. Interconnect narrowing occurs when spot defects induce missing material of interconnects without resulting in a complete cut. The narrow sites of defective interconnects favor electromigration that makes narrow interconnects more likely to induce a chip failure than regular interconnects. In this paper, a layout sensitivity model accounting for narrowing defects is derived. A methodology for predicting the probability of narrow interconnects using the sensitivity model is then proposed. The layout sensitivity model for narrow interconnects is tested and compared to actual and simulated data. Our layout sensitivity model for narrow interconnects predicts the probability of narrowing with 3.1% error, on average. The model is then combined with electromigration constraints to predict mean-time-to-failure of chips manufactured in future technology down to 32nm node. The paper concludes with some other possible applications of the narrow interconnect predictive model.