Electrical and Chemical Properties of the HfO2/SiO2/Si Stack: Impact of HfO2 Thickness and Thermal Budget

In this paper, we investigate the impact of thermal budget and HfO 2 thickness on the chemical and electronic properties of the HfO 2 /SiO 2 /S' stack. High temperature anneal at 750°C induces both the regrowth and reoxidation of the SiO 2 interfacial layer. A bias drop of 1.1 eV is observed along the whole stack via the C Is core-level shift and is ascribed both to the HfO 2 /SiO 2 interfacial dipole and to fixed charges in HfO 2 . Electrical measurements suggest a dipole strength of 0.2 eV. Ellipsometry and UV photoelectron spectroscopy are combined to deduce the HfO 2 electron affinity (1.8 ± 0.2 eV). This value does not change with increasing thermal budget or dielectric thickness. The HfO 2 /Si barrier height is estimated to be 2.1 ± 0.2 eV in agreement with previous internal photoemission results.