ANOMALOUS DEPTH PROFILE OF IMPLANTED FLUORINE IONS IN SIO2 SI/

Fluorine ions have been implanted into SiO2/Si with an energy of 30 ke V at doses of 0.5 and 1 x 10(17) ions/cm(2). Depth profiles of fluorin e have been studied by X-ray photoelectron spectroscopy (XPS) for both as-implanted and annealed samples. It was found that depth profiles o f fluorine in SiO2/Si did not agree with the predicted Gaussian profil es and showed an enhancement of fluorine concentration in SiO2 region far as-implanted samples. It is thought that anomalous depth profiles may be due to rather high diffusion coefficient in Si than that in SiO 2 as a result of fluorine implantation. After annealing at 700 degrees C for 30 min, fluorine concentrations considerably decreased in Si re gion compared with in SiO2 region. It could be considered that the oxi de layers prevent the fluorine diffusion and the fluorine is trapped a t around the SiO2/Si interface. (C) 1998 Elsevier Science B.V.