In this paper, the thermal stability of TiN metal gate with various composition prepared by different preparation technology [(e.g., atomic layer deposition (ALD) or physical vapor deposition (PVD)] on HfO2 high-K dielectric is investigated and compared by physical and electrical analysis. After annealing of the TiN/HfO2 stack at 1000 °C for 30 s, it is observed that: (1) Nitrogen tends to out-diffuse from TiN for all the samples; (2) Oxygen from the interfacial layer (IL) between HfO2 and Si tends to diffuse toward TiN. PVD Ti-rich TiN shows a wider oxygen distribution in the gate stack, and a thinner IL than the N-rich sample. Ti penetration into HfO2 is also observed in the Ti-rich sample, which can potentially lead to the dielectric break-down. Besides, the oxygen out-diffusion can be significantly suppressed for ALD TiN compared to the PVD TiN samples.

The spatial distribution of chemical elements is studied in high-κ, metal-gated stacks applied in field effect transistors. Using the transmission electron microscope (TEM)-based analytical techniques electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray spectroscopy, it is demonstrated that Al2O3 and La2O3 capping layers show distinctly different diffusion profiles. The importance of the EELS collection angle is discussed. Popular chemical distribution models that assume La-rich interface layers are rejected.

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