Effect of Oxygen Postdeposition Annealing on Bias Temperature Instability of Hafnium Silicate MOSFET

Bias temperature instability (BTI) characteristics depending on postdeposition anneal (PDA) conditions were studied using dc (slow process) and pulse (fast process) measurements. In terms of the positive BTI characteristics of nMOSFET, the threshold voltage V_th shift in samples with oxygen PDA was reduced due to the passivation of oxygen vacancy defects. However, the negative BTI (NBTI) characteristics of pMOSFET with pulse measurement showed degradation of the V_th shift in samples with excess oxygen PDA. This phenomenon could be more clearly observed during fast detrapping using rectangular pulse measurements. The origin of NBTI degradation was correlated with the oxygen interstitial defects in the HfSiO layer that were generated during the oxygen annealing process.