N2O Oxidation Kinetics of Ultra Thin Thermally Grown Silicon Nitride: An Angle Resolved X-Ray Photoelectron Spectroscopy Study

ABSTRACTThe oxidation kinetics of ultra thin thermally NH3-nitrided Si3N4 films in N2O ambient has been extensively studied using angle resolved x-ray photoelectron spectroscopy (ARXPS). Ultra thin (7Å) Si3N4 films formed by RTP nitridation of Si in NH3 were annealed in N2O at various temperatures (700 °C - 1000 °C) for 30 sec. ARXPS showed that Si substrate at the Si-Si3N4 interface was oxidized when annealed at 1000 °C for 30 sec, and was accompanied by the oxidation of the top Si3N4 surface. The total film thickness increases 4–5 times of that of the original Si3N4 layer. However, the oxide formed on the top Si3N4 surface is twice as thick as that formed at the Si3N4/Si interface. No interfacial oxide was found when annealing below 900°C, although the formation of the silicon oxide and oxynitride above the Si3N4 layer was still observed.