INFLUENCE OF NITROGEN PROFILE AN ELECTRICAL CHARACTERISTICS OF FURNACE-NITRIDED OR RAPID THERMALLY NITRIDED SILICON DIOXIDE FILMS

Thin silicon dioxide films nitrided in N2O by rapid thermal processing (RTP) or in a classical furnace were investigated by x-ray photoelect ron spectroscopy, secondary ion mass spectroscopy, and electrical meas urements on metal-oxide-semiconductor capacitors. Differences between the two nitridation processes were observed and explained. In lightly nitrided films, nitrogen occupies two configurations. Nitrogen is boun d to three silicon atoms with at least one in the substrate or all thr ee in the oxide. In RTP-nitrided films, both of these species are conf ined to within 1.5 nm of the Si/SiO2 interface. In furnace-nitrided fi lms, the first species is also located close to the interface whereas the second one fills most of the regrown oxide thickness. In furnace-g rown films, which are more heavily nitrided, a third structure due to Si-2=N-O is observed throughout the layer. The electrical characterist ics are well correlated with the amount of nitrogen at the interface t hat is bound to Si atoms in the substrate. (C) 1996 American Institute of Physics.