Anodic Oxidation of Silicon in Organic Baths Containing Fluorine

The anodic oxidation of silicon in organic solvents containing fluorine traces has been investigated by using nuclear microanalysis and electrical measurements. The results obtained show that the fluorine incorporation into the oxide increases with the oxide thickness and with the fluorine content of the bath following the experimental law . Most of the fluorine incorporated is located in a region close to the interface; its surface distribution, studied by ion microprobe mass spectrometry analysis, appears to be uniform. The fluorine incorporation probably obeys a two‐step mechanism. The breakdown field of the anodic layer decreases as a function inversely proportional to the fluorine contamination of the layer. The C ‐ V measurements of the contaminated layers after annealing in H 2 show that the density of charges at the interface is about 10 11 /cm 2 . By comparing composition and electrical measurements, one may predict that fluorine is linked to silicon atoms as is oxygen in silicon oxide.