Electrical Properties of Crystalline Ta2O5 with Ru Electrode

As one candidate capacitor for dynamic random access memories (DRAMs) of 4 Gbit and beyond, we investigated the electrical properties of Ru/Ta2O5/Ru. In this paper, the dielectric constant of Ta2O5 was measured as a function of annealing temperature and, also, its dependence on film thickness was studied. The effect of postannealing, which was performed after forming a capacitor, on the leakage current of Ru/crystalline-Ta2O5/Ru capacitor was evaluated. Additionally, the leakage current was investigated as a function of Ta2O5 film thickness. Through these experiments, a reliable 7 Å Toxeq. of Ta2O5 with a Ru electrode was obtained, which indicates that the Ru/crystalline-Ta2O5/Ru capacitor is a promising candidate for DRAMs of 4 Gbit and beyond.