Nitrogen Incorporation in HfSiO(N)/TaN Gate Stacks: Impact on Performances and NBTI

Abstract

Performance and negative-bias temperature instability (NBTI) on atomic-layer-deposited HfSiON metal-gated pMOSFETs are investigated. The impact of nitrogen incorporation either with plasma nitridation or NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> anneal is studied and compared to the nonnitrided stacks. The capacitance equivalent thickness reduction that is observed in nitrided stacks is compensated by the slight decrease of the hole mobility for the same gate overdrive, resulting in no improvement of the performance. On the other hand, it is shown that nitridation strongly enhances NBTIs in these devices. Based on these results, the necessity of nitrogen incorporation in thin HfSiON/metal gate stacks should be reconsidered.