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 (ΔV
th
) of n-and p-MOSFETs. It is revealed that ΔV
th
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 V
th
curves with or without RTN was simulated. We consequently found that V
th
margin comes close to V
th
window of the SRAM by considering the effect of RTN on ΔV
th
, even at hp 65. Moreover, ΔV
th
due to RTN of the p-MOSFET is comparable with ΔV
th
due to the random dopant fluctuation (RDF) at hp 45 because ΔV
th
due to the RDF is inversely proportional to square root of the gate area (S), while ΔV
th
due to RTN is inversely proportional to S.