Impact of Aging Phenomena on Latches’ Robustness

In this paper, we analyze the effects of aging mechanisms on the soft error susceptibility of both standard and robust latches. Particularly, we consider bias temperature instability (BTI) affecting both
nMOS
(positive BTI) and
pMOS
(negative BTI), which is considered the most critical aging mechanism threatening the reliability of ICs. Our analyses show that as an IC ages, BTI significantly increases the susceptibility of both standard latches and low-cost robust latches, whose robustness is based on the increase in the critical charge of their most susceptible node(s). Instead, we will show that BTI minimally affects the soft error susceptibility of more costly robust latches that avoid the generation of soft errors by design. Consequently, our analysis highlights the fact that in applications mandating the use of low-cost robust latches, designers will have to face the problem of their robustness degradation during IC lifetime. Therefore, for these applications, designers will have to develop proper low-cost solutions to guarantee the minimal required level of robustness during the whole IC lifetime.