Dual-Metal Gate Technology with Metal-Inserted Full Silicide Stack and Ni-Rich Full Silicide Gate Electrodes Using a Single Ni-Rich Full Silicide Phase for Scaled High-k Complementary Metal–Oxide–Semiconductor Field-Effect Transistors

A new dual-metal-gate technology that includes a metal-inserted full silicide stack (MIFS) is proposed for scaled high-k complementary metal–oxide–semiconductor (CMOS) processes. A single Ni-rich full silicide (FUSI) layer is used for both types of MOS field-effect transistors (MOSFETs) without the need to form two different FUSI phases, while a thin-TiN layer is selectively inserted between Ni-rich FUSI and a high-k material only for n-channel MOSFETs (nMOSFETs). A low effective work function (m,eff) of 4.45 eV can be obtained in HfSiON nMOSFETs using MIFS gate electrodes whose structure is Ni-rich FUSI/thin TiN (2 nm). m,eff of Ni-rich FUSI gate electrodes fabricated after the selective removal of TiN from HfSiON is as high as 4.8 eV in HfSiON p-channel MOSFETs (pMOSFETs), which is similar to that obtained for `control' Ni-rich FUSI gate electrodes. Since m,eff remains unchanged with decreasing equivalent oxide thickness (EOT), this dual-metal-gate technology is promising for use in scaled high-k CMOS processes from the viewpoints of m,eff, process compatibility, mobility, and EOT scaling.