Oxygen-induced high-k degradation in TiN/HfSiO gate stacks

We have investigated the diffusion kinetics of Hf in TiN/HfSiO gate stacks. The Hf upward diffusion is found to be independent of interfacial SiO
₂
growth, but depends on the amount of oxygen in the gate stacks. It is also revealed that Hf diffusion into TiN electrode occurs at above 650°C and leads to high-k degradation.