Fast characterization of the Static Noise Margin degradation of cross-coupled inverters and correlation to BTI instabilities in MG/HK devices

A fast BTI characterization setup is introduced to study the Static Noise Margin (SNM) of cross-coupled inverters using metal gate / high-k devices. It is shown that static stress leads to significant SNM degradation due to positive bias temperature instability (PBTI) at high stress voltage consistent with device level data. For the dynamic stress mode the bias temperature instability (BTI) induced degradation of the Pull UP and Pull down devices becomes symmetric which can mask the “worst-case” SNM degradation depending on the initial cell symmetry.