Investigation of low field and high temperature SiO2 and ONO leakage currents using the floating gate technique

In this work a critical analysis of the floating gate technique, for measurement of leakage currents <fA, is presented. Results obtained with thermal SiO2 and with SiO2/Si3N2/SiO2 (ONO) triple stacked layer structures, at temperatures as high as 400 degrees C, are shown. It is demonstrated that the floating gate technique offers an improved sensitivity and a better accuracy. Nevertheless, the existence of a trade off in terms of measurement time and equipment accuracy is noted. Concerning experimental results, a model based on a complete Fowler-Nordheim expression, completed with an ohmic leakage at electric fields approximate to 3 MV/cm, is found to fit SiO2 data and to explain, at least qualitatively, ONO results. (C) 1999 Elsevier Science B.V. All rights reserved.