Radiation-induced interface state generation in MOS devices with reoxidised nitrided SiO2 gate dielectrics

The radiation-induced interface state generation Delta D_it in MOS devices with reoxidised nitrided gate oxides has been studied. The reoxidised nitrided oxides were fabricated by rapid thermal reoxidation (RTO) of rapidly thermal nitrided (RTN) SiO₂. The devices were irradiated by exposure to X-rays at doses of 0.5-5.0 Mrad (Si). It is found that the RTO process improves the radiation hardness of RTN oxides in terms of interface state generation. The enhanced interface ´hardness´ of reoxidised nitrided oxides is attributed to the strainless interfacial oxide regrowth or reduction of hydrogen concentration during RTO of RTN oxides.