Analysis of trap effect on reliability using the charge pumping technology in La-incorporated high-k dielectrics

In this paper, reliability characteristics of nMOSFETs with La-incorporated HfSiON and HfON and metal gate have been studied. HfLaSiON shows greater device degradation by hot carrier (HC) stress than by positive bias temperature (PBT) stress, while HfLaON exhibits similar degradation during HC stress and PBT stress. To evaluate the contribution of bulk trap during PBT stress, a novel charge pumping (CP) technique is applied to extract the distribution of bulk trap (N"b"t) before and after PBT stress. To evaluate permanent damage during HC stress, an appropriate selection of frequency range in CP method is considered. The initial interface trap density of HfLaSiON and HfLaON is similar, while the near-interface trap (N"I"T) density of HfLaSiON after HC stress is equal or greater than that of HfLaON.