Physical understanding of low frequency degradation of NMOS TDDB in High-k metal gate stack-based technology. Implication on lifetime assessment

This paper deals with oxide breakdown (BD) under positive gate voltage in nMOS Devices. First, a stress interruption effect is evidenced on TBD and shown to depend significantly on fabrication process. Then, based on experiments done both with the OTF monitoring methodology and the Fast measurement using Agilent B1530A, the interruption signature on MOS parameters are analyzed. Finally, Maxwell-Wagner instability followed by dielectric relaxation mechanism is found to be responsible for the stress interruption effect on TDDB nMOS.