Two-step stress methodology for monitoring the gate oxide degradation in MOS devices

A recently presented two-step stress method for the analysis of the degradation of SiO2 films is reviewed. By provoking the oxide breakdown in two stages, the test methodology evaluates the degradation of the oxide from statistical breakdown data (without any assumption on the microscopic nature of the oxide degradation) and allows a direct comparison of different tests and oxides of different thickness. The degradation of 8 and 4.3 nm thick oxides is analysed and compared when they are subjected to constant-current and constant-voltage stresses. The results are compared with those obtained using conventional electrical tests. Special attention is given to the evaluation of the degradation using stress induced leakage current data. © 2001 Elsevier Science Ltd. All rights reserved.