Properties and reliability of Ta2O5 thin films deposited on Ta

Abstract

The electrical and reliability properties of reactively sputtered Ta2O5 thin films with Ta as the bottom electrodes forming simple metal insulator metal (MIM) structure. Pt/Ta2O5/Ta/SiO2/n-Si were studied. Ta films were deposited on SiO2/n-Si substrates by sputtering in Ar and in situ annealed at 700 degrees C for 10 min in N-2 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 degrees C for 30s in O-2 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 Ta2O5 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 Ta2O5 storage capacitor.