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

A technique for the simultaneous measurement of the oxide-Si interface properties and of minority carrier lifetime in the Si volume was used for a systematic study of the nitridation process of oxide films. This technique is based on the surface recombination velocity measurements and does not require the formation of a capacitor structure, so it is suitable for the measurement of as-grown interface properties. Oxides grown both in dry and in wet environments were prepared, and nitridation processes in N2O and in NO were compared to N2 annealing processes. The effect of nitridation temperature and duration were also studied, and processes of rapid thermal oxidation and nitridation were compared to conventional furnace nitridation processes. Surface recombination velocity was correlated with N concentration at the oxide-Si interface obtained by SIMS measurements. Surface recombination velocity decreases with increasing N pile-up at the oxide-Si interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments are more effective than N2O treatments in the formation of a N-rich interface layer and in interface state reduction. XPS analyses were used to extend the correlation to thin oxides (3 nm). 12 refs.