The impact of the nitridation process on the properties of the Si-SiO2 interface

A newly developed technique for the simultaneous measurement of the oxide-s ilicon interface properties and of minority carrier lifetime in the silicon volume was used for a systematic study of the nitridation process of oxide films. This technique is based on the surface recombination velocity measu rements, and does not require the formation of a capacitor structure, so it is suitable for the measurement of as-grown interface properties. Oxides g rown both in dry and in wet environments were prepared, and nitridation pro cesses in N2O and in NO were compared to N-2 annealing processes. The effec t of nitridation temperature and duration were also studied, and processes of rapid thermal oxidation (RTO) and nitridation (RTN) were compared to con ventional furnace nitridation processes. Surface recombination velocity was correlated with nitrogen concentration at the oxide-silicon interface obta ined by secondary ion mass spectroscopy (SIMS) measurements. Surface recomb ination velocity (hence surface state density) decreases with increasing ni trogen pile-up at the oxide-silicon interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments a re much more effective than N2O treatments in the formation of a nitrogen-r ich interface layer and, as a consequence, in interface state reduction. X- ray photoelectron spectrometry (XPS) analyses were used to extend our corre lation to very thin oxides (3 nm). (C) 2001 Elsevier Science B.V. All right s reserved.