Role of Hetero Interface of Ionic/Covalent Oxides for Pt/High-k/SiO2/Si MOS Capacitors on Vfb Shift

We have investigated the role of hetero interface of ionic high-k / covalent SiO2 for Pt gate MOS capacitors with strong and weak ionic high-k dielectrics on Vfb shift. The HfO2-based high-k and HfSiON materials of the strong ionic oxide caused the positive Vfb shifts due to dipole, while the Vfb of the HfSiOx-based high-k materials of the weak ionic oxide was almost constant. These suggest that the ionicity of high-k materials is an important because the oxygen diffusion which is related to the dipole formation strongly depends on the ionicity.