Superiority of N2O plasma annealing over O2 plasma annealing for amorphous tantalum pentoxide (Ta2O5) films

Abstract

As-deposited tantalum pentoxide (Ta2O5) films are amorphous. The films will remain amorphous after low-temperature O2 or N2O plasma annealing. High-temperature annealing will produce polycrystalline films where grain boundaries can generate leakage current. It was found that N2O plasma annealing is superior to O2 plasma annealing in terms of leakage current reduction. This can be easily explained by the lower energy required to break the nitrogen-oxygen bond in a N2O molecule compared to the energy required to break the O = O bond in an O2 molecule. We also observed that there is less Si contamination, which may lead to leakage current, in the sample with N2O plasma annealing compared to the sample with O2 plasma annealing.