Analytical electron microscopy investigation of elemental composition and bonding structure at the Sb-doped Ni-fully-silicide/SiO{sub 2} interface
It is very important to control the elemental composition and bonding structure at the gate electrode/gate dielectrics interface in metal-oxide-semiconductor transistor devices because this determines the threshold voltage of the gate electrode. In this study, we investigated the structure at the interface between the antimony (Sb)-doped nickel-fully-silicide gate electrode and SiO{sub 2} dielectrics by employing high-spatial resolution techniques such as energy dispersive x-ray spectroscopy and electron energy-loss spectroscopy using a scanning transmission electron microscope. In one region, we found a thin nickel layer at the NiSi/SiO{sub 2} interface originating from the migration of native oxide at the face of the poly-silicon. In another region, a Sb pileup was detected at the NiSi/SiO{sub 2} interface where the Ni L{sub 3}-edge spectrum showed Ni-Sb bonding, then it was suggested that Sb atoms exist at the bottom of NiSi, substituting for Si atoms in NiSi.