Polarity dependence of charge trapping in poly-silicon gate HfO₂ MOSFETs

摘要

Polarity dependence of charge trapping in poly-Si gate HfO₂ MOSFETs has been systematically studied. It is shown that both the stress-induced threshold voltage shift (ΔV_th) and the transconductance degradation (ΔG_m) are worse in nMOSFETs than in pMOSFETs. For substrate injection in nMOSFETs, electron trapping occurs at the n-poly/HfO₂ interface and/or in bulk HfO₂, whereas for gate injection in pMOSFETs hole trapping near the Si substrate is observed. These results strongly suggest the poly-Si/HfO₂ interface should play an important role in hot carrier induced degradation in HfO₂ gated nMOSFETs.