Hafnium 4f core-level shifts caused by nitrogen incorporation in Hf-based high-k gate dielectrics

Hafnium (Hf) 4f core-level binding energy shifts caused by Hf-N bond formation in hafnium oxynitride (HfOxNy) have been studied by first-principles calculations. Our computational results clearly showed that the Hf 4f core-level binding energies are reduced by 0.36 and 0.65 eV for Hf-N and N-Hf-N bond formation, respectively. These results are in good agreement with chemical shifts observed in the X-ray photoelectron spectroscopy (XPS) of HfOxNy films deposited on a Si(100) substrate. In the present work, we demonstrate that the first-principles calculation is a useful tool to clarify chemical environments of Hf-based high-k gate dielectrics.