SRAM cell optimization for low AVT transistors

In this paper, we describe a six-transistor static random access memory (SRAM) cell optimization methodology for transistors with significantly improved matching, while maintaining compatibility with the baseline design. We briefly describe the reduced AVT transistors and show that they allow substantially improved minimum SRAM operating voltage (Vmin) and improved array leakage. Using an efficient design of experiments (DOE) factorial as a pseudo-Monte Carlo generator, points on the tail of the distribution are directly simulated. The highly efficient method is shown to allow optimization and 'what if' scenario investigations. Simulation and silicon results on a 65-nm process as well as simulation results on a 28-nm process are shown.