A conformal ruthenium electrode for MIM capacitors in Gbit DRAMs using the CVD technology based on oxygen-controlled surface reaction

We have developed a novel CVD-Ru technique, clarified the growth mechanism and fabricated BST capacitors. The growth mechanism is dominated by the surface reaction which is rate-determined by the oxygen supply. Well-tuned conditions enable fabrication of any type of storage node: a concave type with a uniform 20-nm film thickness and a pillar type from a buried film. The electrode/BST interface is degraded by the reduction-oxidation reaction during the Ru-CVD, but post-annealing restores the ideal I-V characteristics.