Fluorine Passivation in Gate Stacks of Poly-$\hbox{Si}/\hbox{TaN}/\hbox{HfO}_{2}$ (and $\hbox{HfSiON}/\hbox{HfO}_{2})/\hbox{Si}$ Through Gate Ion Implantation

Abstract

Fluorine passivation in poly-Si/TaN/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /p-Si and poly-Si/TaN/HfSiON/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /p-Si gate stacks with varying TaN thickness through gate ion implantation has been studied. It has been found that when TaN thickness was less than 15 nm, mobility and subthreshold swing improved significantly in HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nMOSFETs; while there was little performance improvement in HfSiON/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nMOSFETs due to the blocking of F atoms by the HfSiON layer in gate dielectrics, as has been proved by the electron energy loss spectroscopy mapping