Statistical SBD Modeling and Characterization and Its Impact on SRAM Cells

In this paper, we present a physics-based SPICE model for statistical soft breakdown (SBD) in ultrathin oxide. Statistical SBD induces an increase in gate leakage current (IG_BD) based on the time to breakdown (tBD) and the location of the percolation path in the channel. The proposed model has been validated with experimental data, and fed into circuit simulators to predict the degradation of device/circuit performance. Using the model, we analyzed the impact of the increased IG_BD due to the first SBD on cell stability and performance in SRAM cells. We observed that IG_BD variation due to SBD increases READ and WRITE failure probability, resulting in reduced lifetime.