Nitrogen bonding configurations near the oxynitride/silicon interface after oxynitridation in N2O ambient of a thin SiO2 gate

The identification of the bonding environments and their progressive modifications upon reaching the oxynitride/silicon interface, in a SiO2/SiOxNy /Si structure, have been investigated by means of X-ray photoemission spectroscopy (XPS). The SiO2 film was grown at 850 degrees C by means of a mixed dry-steam process, followed by a 60 min, 950 degrees C furnace oxynitridation in NO gas. A depth profile analysis was carried out by a progressive chemical etching procedure, reaching a residual oxide thickness of about 1.2 nm. XPS analysis of the Si 2p and N 1s photoelectron peaks pointed out that the chemistry of the oxynitride layer is a rather complex one. Four different nitrogen bonding environments were envisaged. Both the overall nitrogen content, which rises up to 2.5%, and its bonding configurations are progressively changing while moving towards the silicon interface. (C) 2007 Elsevier Ltd. All rights reserved.