Detection of defect states responsible for leakage current in ultrathin tantalum pentoxide (Ta2O5) films by zero-bias thermally stimulated current spectroscopy

Defect states responsible for leakage current in ultrathin (physical thickness <10 nm) tantalum pentoxide (Ta2O5) films were measured with a novel zero-bias thermally stimulated current technique. It was found that defect states A, whose activation energy was estimated to be about 0.2 eV, can be more efficiently suppressed by using N2O rapid thermal annealing (RTA) instead of using O-2 RTA for postdeposition annealing. The leakage current was also smaller for samples with N2O RTA than those with O-2 RTA for postdeposition annealing. Hence, defect states A an quite likely to be important in causing leakage current. (C) 1997 American Institute of Physics.