Impact of Polarity and Hf concentration on Breakdown of HfSiON/SiO2 Gate Dielectrics

We have investigated the impact of polarity and Hf concentration on HfSiON/SiO₂ gate dielectrics breakdown with TZDB and TDDB. In TZDB, gate leakage currents at breakdown in negative bias are much smaller than those in positive bias without regard to accumulation or inversion states. Since electric fields at breakdown are not all the same, the breakdown mechanism cannot be explained with a simple thermochemical model. In TDDB, thermochemical breakdown of HfSiON itself is adequate for nMOS in inversion. On the other hand, breakdown of pMOS in inversion is affected by the carrier currents. The breakdown mechanisms are strongly dependent on the polarity and Hf concentration