Effective p-type doping for leakage current reduction of ZrO2 by employing Sc2O3

Abstract

This study explores the integration of scandium oxide (Sc₂O₃) as a novel p-type dopant to enhance the performance of zirconium dioxide (ZrO₂)-based metal-insulator-metal (MIM) capacitors. Compared to traditional aluminum oxide (Al₂O₃) inserting layers, Sc₂O₃ exhibits superior structural compatibility with ZrO₂, effectively preserving crystallinity and minimizing grain size degradation. Systematic evaluations reveal that employing Sc₂O₃ as an inserting layer (IL) prevents significant crystallinity degradation up to a thickness of 1 nm and only slight deterioration at 2 nm. This effect is particularly pronounced in ultrathin ZrO₂ films, where Sc₂O₃ also promotes a transition to the cubic phase, mitigating k-value reduction. Furthermore, Sc³⁺ doping significantly reduces leakage current without compromising the dielectric constant. Consequently, the Sc₂O₃-based ZrO₂ (ZSZ) structure achieved a minimum equivalent oxide thickness (t_ox) of 0.71 nm, marking a 5.3 % improvement over pristine ZrO₂. These findings establish Sc₂O₃ as a promising alternative to conventional Al₂O₃ for advancing high-k dielectric applications.