Evaluation of DRAM CMOS Reliability during BTI and TDDB under AC and DC conditions

Extensive Bias Temperature Instability (BTI) and Time Dielectric Dependent Breakdown (TDDB) study is presented in this paper on DRAM CMOS Periphery devices. The study focuses on degradation evaluated with fast measurement both in DC Mode and AC Mode. It is highlighted that while Negative BTI (NBTI) show frequency independence (Mode-B) of its degradation, longer TDDB with higher frequency is observed in PMOS TDDB. On the other hand, NMOS TDDB behavior show degradation at lower frequencies and improvement at higher frequencies while Positive BTI (PBTI) is also frequency independent. The discrepancy between these results highlights the need to further investigate the correlation of those mechanism.