Effect of silicon surface cleaning procedures on oxidation kinetics and surface chemistry

The effect of surface cleaning procedures on the kinetics of thermal oxide growth on silicon is presented. The goal is to relate the properties of the cleaned surface (composition, chemistry, impurity content) to the changes in oxide growth mechanisms. Experimentally, silicon (100) wafers were given different variations of an RCA clean, and then oxidized in dry O₂ at 900°C producing oxides with thicknesses between 170 and 3900 Å. The results, in general agreement with earlier studies, show that the percentage difference in thickness is strongly dependent on oxide thickness. The data, which are explained in terms of the predictions of a linear-parabolic and a parallel oxidation model, suggest that the surface cleans do not alter the diffusion of molecular oxygen in the oxide. Auger analysis of the surfaces shows that there is a substantial carbon contamination on the HF stripped wafer which is considerably reduced after a 5 min N₂ anneal.