Role of oxygen transfer for high-k/SiO₂/Si stack structure on flatband voltage shift

We investigate the difference of flatband voltage (Vfb) behavior in high-k/SiO₂/Si stack structure due to oxygen vacancy (Vo) and additional oxygen generated by the reduction and oxidation annelaing processes, respectively. The Vfb of Mg and La-incorporated Hf-based high-k dielectrics is also influenced by Vo generation in high-k layer. We found that the non-linear relationships of Vfb behavior appears in HfSiO_x, Mg ²⁺-HfSiO_x, and La³⁺-HfSiO_x dielectrics as a function of the oxidation annealing temperature, while the HfO₂, N³⁺-HfSiO_x, Mg²⁺-HfO ₂, and La³⁺-HfO₂ dielectrics show the linear relationships of Vfb shift by introducing additional oxygen. Furthermore, it is clear that the Vfb shift of all high-k materials satisfies the diffusion equation; which indicates that the oxygen transfer in high-k layer is a dominant factor in determining Vfb. We found that the oxygen diffusion in high-k materials can be ordered as follows: Mg²⁺-HfO₂, La ³⁺-HfO₂ and N³⁺-HfSiO_x > HfO ₂ >> La³⁺-HfSiO_x > HfSiO_x and Mg₂₊-HfSiO_x. Note that the oxygen transfer in high-k materials is very important to recognize mechanism of Vfb shift for high-k/SiO₂/Si stack structure.