Influence of native oxides on the reliability of ultrathin gate oxide

The influence of wet cleaning processes, such as the SC-1 and H2O2 processes, on the time dependent dielectric breakdown (TDDB) of ultrathin gate oxide was investigated. A large difference in the reliability by wet cleaning processes was observed, especially when an electrode is an anode. The reliability of the gate oxide by the H2O2 process was worse than SC-1. It was found by Fourier transformed infrared attenuated total reflection (FT-IR-ATR) analysis that the amount of structural imperfection of native oxides formed in H2O2 was larger than SC-1. Since stress-induced positive charges which affect the TDDB properties are generated near the anode- side oxide interface, a large amount of structural imperfection in the native oxides formed in H2O2 probably results in a defective thermal oxide surface, leading to an increase in the generation and trapping of positive charge.