Oxygen diffusion through RuO2 bottom electrode of integrated ferroelectric capacitors

Abstract

RuO2 thin films deposited on the barrier layers of TiN and Ru have been annealed in an oxygen ambient at 650 degrees C for 30 min. The thermal stability of the RuO2/diffusion barrier structure was investigated by Auger Electron Spectroscopy (AES) to find the suitable structure for the bottom electrode of integrated ferroelectric capacitors. RuO2 thin films were stably fabricated on TiN and Ru layers with sharp interfaces within RuO2/TiN and RuO2/Ru. It was found that RuO2 could not prevent the diffusion of oxygen through itself and oxidation of the underlying TiN layer. On the other hand, the underlying Ru layer was found to provide a barrier to oxygen diffusion under the same annealing conditions. From these results, RuO2/Ru/poly-Si is thought to be the most available structure for the bottom electrode. (C) 1999 Elsevier Science B.V. AU rights reserved.