RuO2/TiN-based storage electrodes for (Ba, Sr)TiO3 dynamic random access memory capacitors

Sputtered (Ba, Sr)TiO 3 (BST) thin film capacitors have been fabricated with thick RuO 2 /TiN-based storage electrodes and poly-Si contact plugs, and the electrical properties of the storage electrodes have been studied. The electrode height was higher than 450 nm and the contact size was 0.8 x 0.8 μm 2 . Resistance of the storage electrodes including contact plugs can be evaluated from the dispersion observed in capacitance-frequency measurements. TiN oxidation at the RuO 2 /TiN interface and native oxide at the TiN/Si contact contribute to the electrode resistance of RuO 2 /TiN electrodes. With increasing BST deposition temperature, the thickness of oxidized TiN in RuO 2 /TiN electrbdes increases and the electrode resistance increases correspondingly. A Ru layer inserted at the RuO 2 /TiN interface, a TiN/TiSi 2 /Si junction and rapid thermal annealing in N 2 ambient of the TiN layer are effective ways to reduce the resistance of RuO 2 /TiN-based electrodes.