Effect of Post-Annealing on Electrical Properties of Ta₂O₅ Thin Film Deposited by Pecvd Using TaCl₅ and N₂O

Abstract

The effect of high temperature annealing, in the temperature range of 600∼900°C on the electrical properties and microstructure of tantalum pentoxide (Ta2O5) film deposited by PECVD was studied. The leakage current of the Ta2O5 film annealed at 600°C showed a minimum value in this study. However, it was found that the leakage current in the polycrystalline Ta2O5 film annealed above 800°C was decreased by increasing the annealing temperature. The dielectric constant of the annealed Ta2O5 film was 26 at 600°C, and decreased with the same tendency as leakage current characteristics. TEM and XRD analysis indicated that the microstructure of the Ta2O5 film annealed above 800°C was of ε-Ta2O5 with hexagonal crystal structure. Furthermore, TEM and AES observations revealed that Ta-O-Si transition layers were formed between annealed Ta2O5 layer and Si substrate. The electrical properties of the Ta2O5 films were discussed in terms of interface modification and film densification due to post-annealing