An advanced statistical compact model strategy for SRAM simulation at reduced VDD

Accurate statistical compact model extraction and circuit simulation are key issues in contemporary SRAM design. The high statistical variability of the small SRAM cell transistors in combination with high density leads to yield problems determined by 5-6σ deviations from the mean. The compact modeling approach presented in this paper utilizes a firm understanding of the physical phenomenon underlying device variability. Its illustration is based on comprehensive `atomistic´ 3D device simulations. Extracted statistical models are then utilized in SRAM SNM simulation, and benchmarked against Gaussian V_T based simulation. The results show that aside from the increasing error in the yield estimate with the reduction of the supply voltage V_DD, Gaussian V_T simulations also fail to capture the decorrelation between nominal SNM and SNM.