Investigation of low field and high temperature SiO 2 and ONO leakage currents using the floating gate technique

Abstract

In this work a critical analysis of the floating gate technique, for measurement of leakage currents <fA, is presented. Results obtained with thermal SiO 2 and with SiO 2/Si 3N 4/SiO 2 (ONO) triple stacked layer structures, at temperatures as high as 400°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 ≈3 MV/cm, is found to fit SiO 2 data and to explain, at least qualitatively, ONO results.