 Even with the introduction of new materials like hafnium oxide in the gate stack, NBTI remains and is often exacerbated by additional charge trapping in the high-κ layer.With the introduction of high κ metal gates, a new degradation mechanism has become more important, referred to as PBTI (for positive bias temperature instabilities), which affects nMOS transistor when positively biased.In this case, no interface states are generated and 100% of the Vth degradation may be recovered.