Impact of threshold voltage fluctuation due to random telegraph noise on scaled-down SRAM

The impact of a random telegraph noise (RTN) on a scaled-down SRAM is shown for the first time. To estimate the impact on SRAM, we statistically analyzed a threshold voltage fluctuation (DeltaVth) of n-and p-MOSFETs. It is revealed that DeltaVth of the p-MOSFET is larger than that of the n-MOSFET. This difference can be explained by considering the followings: (i) number- and mobility-fluctuation models of RTN (ii) the difference in the capture cross section between electron and hole. In addition, based on these results, SRAM margin enclosed by read / write Vth curves with or without RTN was simulated. We consequently found that Vth margin comes close to Vth window of the SRAM by considering the effect of RTN on DeltaVth, even at hp 65. Moreover, DeltaVth due to RTN of the p-MOSFET is comparable with DeltaVth due to the random dopant fluctuation (RDF) at hp 45 because DeltaVth due to the RDF is inversely proportional to square root of the gate area (S), while DeltaVth due to RTN is inversely proportional to S.