Structure and Electrical Properties of Thin Ta2O5 Deposited on Metal Electrodes

Abstract
The structure and electrical properties of chemical vapor deposition (CVD)-Ta2O5 thin films on Pt, Ru and poly-Si electrode were studied. With 750°C annealing after Ta2O5 deposition, a 12-nm-thick Ta2O5 on Pt and Ru shows a SiO2 equivalent thickness (t eq) of 0.9 nm. We found that Ta2O5 on Pt and Ru shows (110) and (001) orientation, respectively. There is no interaction between Ta2O5 and these electrodes with 750°C annealing. t eq on Pt and Ru decreases with annealing temperature increase. On the other hand, Ta2O5 on poly-Si is randomly oriented and its t eq does not change with annealing temperature increase. The relative dielectric constant of Ta2O5 on Pt and Ru, which is highly oriented with 750°C annealing, is estimated over 50. It is clear that the Ta2O5 electrical properties are strongly related with its crystallinity.