Effects of temperature and pressure in oxynitridation kinetics on Si(100) with N2O gas

We have investigated oxynitridation of Si(100) surfaces with nitrous oxide (N2O) gas in a wide range of substrate temperatures (600-1000 degrees C) and N2O pressures (10(-2)-10(2) Pa). The growth rate and atomic composition of the oxynitride layer have been measured by in situ x-ray photoelectron spectroscopy. The surface morphology of the oxynitride layer has been also observed by scanning electron microscopy. The results show that in higher N2O pressure ( > 1 Pa) regime, the nitridation reaction is suppressed by the oxide layer, which quickly forms on the surface. On the other hand, in lower pressure ( < 1 Pa) and higher substrate temperature ( > 900 degrees C) regime, the nitridation reaction strongly occurs because of the active oxidation (etching reaction), which causes the surface roughness. It is found by argon-ion-sputtering measurements that the nitride layer locally exists only near the surface at the reduced N2O pressure. We discuss qualitatively the oxynitridation kinetics and the effective condition for growing the oxynitride layer.