Leakage current control of Y-HfO2 for dynamic random access memory applications via ZrO2 stacking.

Pristine HfO 2 tends to have a monoclinic phase with a low dielectric constant. Reportedly, yttrium(Y) doping has been used to induce the tetragonal phase in HfO 2 , with Y contributing to the formation of the tetragonal phase and improving the crystallinity. However, Y doping in HfO 2 forms oxygen vacancies, resulting in a relatively high leakage current. Owing to the difficulty in suppressing the oxygen vacancies crucial for inducing the tetragonal phase, we focused on another significant leakage current path: the grain boundary. Introducing a heterostructure is expected to reduce the grain size and mitigate the leakage current by increasing the length of the leakage path. This study compares the dielectric constant and leakage current based on the stacking sequence of ZrO 2 and Y-doped HfO 2 (Y-HfO 2) and elucidate the underlying differences through electrical analysis. Additionally, crystallographic analysis reveals the reasons for the structural order-dependent variations in the electrical properties. Finally, the structure with a Y-HfO 2 layer at the bottom demonstrates advantages in achieving a lower leakage current. [ABSTRACT FROM AUTHOR]