Time-Dependent Dielectric Degradation (TDDD) Influenced by Ultrathin Film Oxidation Process

A complete hole-induced breakdown model suggests that the intrinsic oxide breakdown under an optimal low-field operation lifetime is not a critical limitation in thin oxide films (30–180 Å). Also, buildup of the oxide trapped charges and generation of the Si/SiO2 interface states during electrical stress, which is closely related to water-related bond breaking inside/at the interface of the amorphous thin oxide networks, decreases in a thin oxide film (∼50 Å). On the other hand, electrical stress-induced leakage current (SILC) through the oxides is markedly increased in the oxide film of around 50 Å thickness; also, the SILC is apparently dependent on the ultrathin film oxidation process. The origin of SILC can be modeled by the Si–O weak/strained bonds inside the amorphous thin oxide films in contrast to the water-related bond-breaking model. Thus the SILC phenomenon is a very important problem in the ultrathin oxide film reliability. Due to the need for a new measure of wafer level reliability to SILC, a time-dependent dielectric degradation (TDDD) method was developed for the evaluation of ultrathin oxide film reliability.