0.6nm-EOT high-k gate stacks with HfSiO_x interfacial layer grown by solid-phase reaction between HfO_2 and Si substrate

摘要

We have developed a process for forming an ultra-thin HfSiO_x interfacial layer (HfSiO_x-IL) for high-k gate stacks. The HfSiO_x-IL was grown by the solid-phase reaction between HfO_2 and Si-substrate performed by repeating the sequence of ALD HfO_2 deposition and RTA. The HfSiO_x-IL grown by this method enables the formation of very uniform films consisting of a few mono-layers, and the dielectric constant of the HfSiO_x-IL is about 7. The FUSI-NiSi/HfO_2 gate stacks with HfSiO_x-IL have achieved 0.6 nm EOT, a very low gate leakage currents between 1 A/cm~2 and 5X 10~(-2) A/cm~2, an excellent subthreshold swing of 66mV/dec, and a high peak mobility of 160cm /Vs compared to the reference samples without HfSiO_x-IL. These results indicate that the HfSiO_x-IL has a good quality compared to the SiO_2 interfacial layer grown by oxygen diffusion through HfO_2 films.