Leakage current mechanism and effect of Y₂O₃ doped with Zr high-K gate dielectrics

In this study, a Y₂O₃ film doped with Zr was fabricated to form two stacked structures, Al/ZrN/Y₂O₃ + Zr/Y₂O₃/p-Si (with Zr in the upper layer) and Al/ZrN/Y₂O₃/Y₂O₃ + Zr/p-Si (with Zr in the lower layer), at rapid thermal annealing (RTA) temperature range of 550, 700, and 850 °C. To analyze the leakage current mechanism, leakage current versus voltage (I-V) and capacitance versus voltage (C-V) characteristics of these two structures were first investigated. By analyzing Schottky emission (SE) and the fit of its equation with experimental data and parameters, dielectric constants were computed to be 11.3 and 6.34, equivalent oxide thicknesses (EOTs) were determined to be 2.42 and 4.3 nm, Schottky barrier heights were calculated to be 0.81 and 0.82 eV, and dynamic dielectric constants were determined to be 13 and 8 for structures with Zr in the upper and lower layers, respectively. By analyzing Poole-Frenkel (P-F) emission and the fit of its equation with experimental data and parameters, trap energy levels were computed to be 0.45 and 0.5 eV, and dynamic dielectric constants were determined to be 1.65 and 2.61 for structures with Zr in the upper and lower layers, respectively. The characteristics of ln(J/T²) versus E^0.5 and ln(J/T²) versus 1000T in SE and P-F emission were linear, thus conforming to the theoretical equations. Finally, the results of computed parameters in the two structures were compared to validate the leakage current mechanism.