Analysis of the effect of the gate oxide breakdown on SRAM stability

We have investigated the effects of oxide soft breakdown (SBD) on the stability of CMOS 6T SRAM cells. Gate-to-diffusion leakage currents of 20-50 microA at the n-FET source can result in a 50% reduction of noise margin. Breakdown at other locations in the cell may be less deleterious depending on n-FET width. This approach gives targets for tolerable values of leakage caused by gate oxide breakdown.