RuO2/TiN-Based Storage Electrodes for (Ba, Sr)TiO3 Dynamic Random Access Memory Capacitors

Abstract
Sputtered (Ba, Sr)TiO3 (BST) thin film capacitors have been fabricated with thick RuO2/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 0.8×0.8 µ m2. Resistance of the storage electrodes including contact plugs can be evaluated from the dispersion observed in capacitance-frequency measurements. TiN oxidation at the RuO2/TiN interface and native oxide at the TiN/Si contact contribute to the electrode resistance of RuO2/TiN electrodes. With increasing BST deposition temperature, the thickness of oxidized TiN in RuO2/TiN electrodes increases and the electrode resistance increases correspondingly. A Ru layer inserted at the RuO2/TiN interface, a T i N/T i S i 2/S i junction and rapid thermal annealing in N2 ambient of the TiN layer are effective ways to reduce the resistance of RuO2/TiN-based electrodes.

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