Investigation of high-K gate stacks with epitaxial Gd2O3 and FUSI NiSi metal gates down to CET=0.86 nm

Novel gate stacks with epitaxial gadolinium oxide (Gd2O3) high-k dielectrics and fully silicided (FUSI) nickel silicide (NiSi) gate electrodes are investigated. Ultra-low leakage current densities down to 10–7 A cm–2 are observed at a capacitance equivalent oxide thickness of CET=1.8 nm. The influence of a titanium nitride (TiN) capping layer during silicidation is studied. Furthermore, films with an ultra-thin CET of 0.86 nm at a Gd2O3 thickness of 3.1 nm yield current densities down to 0.5 A cm−2 at Vg=+1 V. The extracted dielectric constant for these gate stacks ranges from k=13 to 14. These results emphasize the potential of NiSi/Gd2O3 gate stacks for future material-based scaling of CMOS technology.