High-density metal-insulator-metal capacitors using Gd2O3-based dielectrics

Metal-insulator-metal (MIM) capacitors have been fabricated with single dielectric stack (Gd₂O₃) and bilayer dielectric stacks of Eu₂O₃ and Gd₂O₃ (Gd₂O₃/Eu₂O₃ and Eu₂O₃/Gd₂O₃) for analog and DRAM applications. While Pt/Gd₂O₃/Pt capacitors provide the highest capacitance density (15 fF/μm²), Pt/Gd₂O₃/Eu₂O₃/Pt and Pt/Eu₂O₃/Gd₂O₃/Pt capacitors provide lower leakage current densities (1.2×10^-5 A/cm² and 2.7×10^-5 A/cm², respectively at -1 V) and lower quadratic voltage coefficient of capacitance (VCC) (331 ppm/V² and 374 ppm/V², respectively at 1 MHz). The barrier/trap heights and defect densities have been computed for the faricated devices. The improved performance of bilayer dielectric stacks (Gd₂O₃/Eu₂O₃ and Eu₂O₃/Gd₂O₃) is attributed to lower defect densities and higher barrier/trap heights.