Impact of air-induced poly-Si/oxynitride interface layer degradation on gate-edge leakage

The air-sensitivity of the poly-Si interface in MOS transistors and its impact on the electrical properties are studied. It is found that the gate leakage localized near the side of air-exposed edges is possibly caused by air-induced degradation of the poly-Si interface, which supplies mobile NH₃-like species to the gate edge side surface, resulting in the formation of a non-stoichiometric as well as impurity-retaining, hence conductive, SiO_xN_y edge layer. Control of the air-sensitive interfacial oxynitride and its NH₃-related decomposition reaction is considered to be essential for improving the gate-edge leakage.