Properties and reliability of Ta2O5 thin films deposited on Ta

The electrical and reliability properties of reactively sputtered Ta₂O₅ thin films with Ta as the bottom electrodes forming simple metal insulator metal (MIM) structure. A Pt/Ta₂O₅/Ta/SiO₂/n-Si structure was studied. Ta films were deposited on SiO₂/n-Si substrates by sputtering in Ar and in situ annealed at 700°C for 10 min in N₂ at a chamber pressure of 20 mTorr. We compared the effectiveness of both as-deposited and annealed Ta bottom electrode on the leakage characteristics of Ta₂O₅ thin films. Ta₂O₅ films subjected to rapid thermal annealing (RTA) process at 800°C for 30 s in O₂ crystallized the film, decreased the leakage current density and resulted in reliable time-dependent dielectric breakdown characteristics. We also envisaged the influence of the surface roughness and morphology of the Ta bottom electrode in modifying the resultant microstructure of the annealed Ta ₂O5 films. Present studies demonstrate the use of Ta as a potential bottom electrode material replaces the precious metal electrodes and simplifies the fabrication process of the Ta₂O ₅ storage capacitor