Achieving Equivalent\nOxide Thickness Scaling of a\nZrO<sub>2</sub> Dielectric Thin Film via Gd Doping without Sacrificing\nTetragonal Crystallinity

In this study, we examine the potential of Gd dopants\nto replace\nAl dopants in ZrO<sub>2</sub>-based dynamic random-access memory (DRAM)\ncapacitors. While using Al dopants is a practical approach to solving\nthe leakage current problem of ZrO<sub>2</sub>, it induces tetragonal\ncrystallinity deterioration of the ZrO<sub>2</sub> dielectric thin\nfilm, thereby decreasing the capacitance. The Gd-doped ZrO<sub>2</sub> dielectric thin film demonstrated promising results in suppressing\nthe leakage current while preserving the tetragonal crystallinity.\nMoreover, the suppression of the leakage current mechanism by Gd doping\nis discussed and shown to be due to the increasing conduction band\noffset caused by the acceptor (p-type) doping effect. Consequently,\nthe Gd-doped ZrO<sub>2</sub> achieved a minimum equivalent oxide thickness\nvalue of 0.76 nm while satisfying the specifications of the DRAM leakage\ncurrent density (<10<sup>–7</sup> A/cm<sup>2</sup> at an\napplied voltage of +0.8 V).