Yttrium- and Terbium-Based Interlayer on \hbox and \hbox Gate Dielectrics for Work Function Modulation of Nickel Fully Silicided Gate in nMOSFET

Novel yttrium- and terbium-based interlayers (Y IL and Tb IL , respectively) on SiO 2 and HfO 2 gate dielectrics were employed for NMOS work function Phi m modulation of undoped nickel fully silicided (Ni-FUSI) gate. Bandedge Ni-FUSI gate Phi m of ~4.11 and ~4.07 eV was obtained by insertion of ultrathin (~1 nm) Y IL and Tb IL , respectively, on the SiO 2 gate dielectric in a gate-first process (with 1000 degC anneal). NiSi Phi m on SiO 2 could also be tuned between the Si midgap and the conduction bandedge E C by varying the interlayer thickness. The achievement of NiSi Phi m around 4.28 eV on the HfO 2 gate dielectric using interlayer insertion makes this an attractive Phi m modulation technique for Ni-FUSI gates on SiO 2 and high-k dielectrics