Thickness and post-annealing effects of the sputtered La-capping layer inserted between the TiN gate and Hf-based dielectrics.

We investigated effects of the sputtered La-capping layer inserted between TiN and Hf-based dielectrics, HfO2 and HfSiO4/HfO2, mainly focusing on effective work function (EWF) and equivalent oxide thickness (EOT) changes by modulation of its thickness and post-metal annealing (PMA). The use of thin La capping up to 5 Å showed a linear flatband voltage (V(FB)) shift of -60 mV/Å, regardless of gate dielectrics. However, with the increase of the La thickness, a slight increase in EOT was observed for HfO2, whereas a negligible change in EOT was shown for the HfSiO4/HfO2 bilayer.