Yttrium- and Terbium-Based Interlayer on $ \hbox{SiO}_{2}$ and $\hbox{HfO}_{2}$ Gate Dielectrics for Work Function Modulation of Nickel Fully Silicided Gate in nMOSFET

Abstract

Novel yttrium- and terbium-based interlayers (YIL and TbIL, respectively) on SiO2 and HfO2 gate dielectrics were employed for NMOS work function Phim modulation of undoped nickel fully silicided (Ni-FUSI) gate. Bandedge Ni-FUSI gate Phim of ~4.11 and ~4.07 eV was obtained by insertion of ultrathin (~1 nm) YIL and TbIL, respectively, on the SiO2 gate dielectric in a gate-first process (with 1000 degC anneal). NiSi Phim on SiO2 could also be tuned between the Si midgap and the conduction bandedge EC by varying the interlayer thickness. The achievement of NiSi Phim around 4.28 eV on the HfO2 gate dielectric using interlayer insertion makes this an attractive Phim modulation technique for Ni-FUSI gates on SiO2 and high-k dielectrics