ON THE CHARGE BUILDUP MECHANISMS IN GATE DIELECTRICS

The variation of the bulk oxide charge build-up characteristics of gate dielectrics after different Fowler-Nordheim stress conditions are investigated. It is proved that none of the degradation mechanism known so far are capable of explaining the evolution of the bulk oxide degradation features after high field electrical stress. Instead, it is shown that the degradation process can be attributed to a universal charge build-up empirical law. Besides, a new and simple method for analyzing the so-called ''turn-over'' phenomenon in MOS structures is proposed. The method enables the monitoring of the whole Si band gap, at room temperature and without any assumption concerning the nature of the interface traps (donor-or acceptor-like). Finally, comparison between SiO2 and nitridated oxides in N2O ambient is conducted in terms of volume/interface trapping properties.