Suresh Uppal

Effective work-function control technique applicable to p-type FinFET high-k/metal gate devices

Abstract In this work, we investigated the effect of so-called WF (Work Function) setting anneal (high temperature annealing on TiN/HfO 2 stack) on gate stack properties. It was found that intermixed layer created in-between TiN and HfO 2 during WF setting anneal has negative fixed charge and reduces pFET V t (positive V t shift). In addition, higher anneal temperature further reduces pFET V t while keeping nFET V t almost unchanged. This could be explained by passivation of oxygen vacancies in HfO 2 with diffused oxygen from TiN layer. By combining these effects, one can further push effective work function towards valence band edge which enables wider coverage of transistor V t option.