Oxidation suppression in ytterbium silicidation by Ti∕TiN bicapping layer

Ytterbium (Yb) silicide is a promising contact material due to its low contact resistance and small Schottky barrier height in contact with n-type Si. However, as one of the rare earth metals, Yb is easily oxidized during physical vapor deposition and rapid thermal annealing. In this article, a bilayered Ti∕TiN cap is proposed and demonstrated to effectively suppress oxidation during Yb silicidation. The authors’ results reveal that diffusion of Ti atoms in the TiN layer plays a key role in oxidation suppression.