The defect states which were responsible for leakage currents in ultra-thin (less than 10nm) Ta2O5 films were measured by using a novel zero-bias thermally stimulated current technique. It was found that defect states, whose activation energy was estimated to be about 0.2eV, could be more efficiently suppressed by using N2O rapid thermal annealing instead of O2 rapid thermal annealing for post-deposition treatment. The leakage current was also smaller for samples given N2O rapid thermal annealing than for those subjected to O2 rapid thermal post-deposition annealing. Hence, the above defect states were expected to be important in causing leakage currents.

W.S.Lau, L.Zhong, A.Lee, C.H.See, T.Han, N.P.Sandler, T.C.Chong: Applied Physics Letters, 1997, 71[4], 500-2