New insights on the PBTI phenomena in SiON pMOSFETs

The physical origin of both Negative- and Positive Bias Temperature Instability (N-/PBTI) is still unclear and under debate. We analyzed the rarely studied recovery behavior after PBTI stress in pMOSFETs and compared it with NBTI data obtained from the same technology. While recovery after short stress times is consistent with the previously reported emission of trapped holes, for stress times larger than 10 ks we observe an unusual recovery behavior not reported before. There, the device degradation appears to continue during recovery up to approximately 30 s. Only after that time “normal” recovery behavior dominates. We thoroughly analyze this new observation as this may have significant consequences regarding our understanding of both PBTI and NBTI.