Multilevel current stress technique for investigation thin oxide layers of MOS structures

Abstract

In this study, a new technique of multilevel current stress for investigation thin oxide layers of MOS structures is proposed. This technique allows to investigate the generation and relaxation of positive and negative charges, accumulating in, nano-thickness gate dielectric of MOS structures under many stressing situations. The parameters characterizing the change of charge state in the thin oxide layers of MOS structures during the stress have been monitored by means of time dependence of voltage shift applied to a sample during the injection. The method takes into account the process of the MOS capacitance charging by the constant current pulse. In comparison with the conventional techniques our method is nondestructive and enables to reduce the high-field stress time while measuring the injection current-voltage characteristics of the MOS-structure. We consider this method to provide higher accuracy and to decrease the probability of dielectric breakdown. The application of present technique was carr mied out during the investigation of charge generation and relaxation, during and after high-field tunnel injection of electrons in thin thermal film of SiO2. The thin oxide layers of MOS structures after plasma and irradiation treatments also are investigated.