The impact of gate-oxide breakdown on SRAM stability

Abstract

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 μA 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.