Modulation of the Ni FUSI workfunction by Yb doping: from midgap to n-type band-edge

The key result in this work is the experimental demonstration that adding Yb to Ni FUSI allows for tuning the work function (WF) from midgap (NiSi ~4.72 eV) to n-type band-edge (~4.22 eV) on thin SiON, maintaining same EOT. In addition, we did not observe any interface adhesion issues found in other reports when WF is modulated by dopants such as As or Sb. We also show that reliability is similar to Ni FUSI. This is a promising technique for nFET gate electrode formation and enables dual gate CMOS technologies for 45 nm and beyond in a manufacturable way