In advanced technology nodes, bias temperature instability (BTI) has emerged as a
prominent reliability concern. The worst-case effects of BTI occur during specific workload
phases in which flip-flops (FFs) on a critical path do not switch their logic values for a long
duration. These inactive FFs in the circuit experience accelerated workload-dependent static-
BTI (S-BTI) stress. The aging effect of S-BTI for a few hours has been shown to be equivalent
to one year of aging due to dynamic BTI, which can eventually cause circuit failure. The …

Unlike dynamic BTI which involves both stress and recovery periods, long periods of
inactivity in parts of the circuit can result in static BTI (S-BTI) stress. This phenomenon can
accelerate the aging effect on circuit delay degradation. The delay degradation due to S-BTI
stress of a few hours on logic circuits can be equivalent to D-BTI stress for 1 year. The critical
point of operation of a circuit is when the circuit enters a dynamic phase after a long duration
of static-stress phase. A worst-case timing analysis should be carried out considering this …