The diffusion of defects, during the thermal growth of SiO2 films on (100)Si in dry O2, was investigated by using sequential treatments in 16O2 or 18O2. The 18O depth profiles were measured, to a resolution finer than 1nm, by using the nuclear reaction narrow resonance: 18O(p,α)15N. The profiles confirmed that, just below the surface, an exchange occurred between O atoms from the gas phase and those from the silica; even for silica films that were thicker than 20nm. This was not predicted by the Deal-Grove model. The diffusion of O-related defects took place in the near-surface region, with an apparent diffusion coefficient of 4.33 x 10-19cm2/s, during oxidation at 930C under an O pressure of 100mbar.

J.J.Ganem, I.Trimaille, P.André, S.Rigo, F.C.Stedile, I.J.R.Baumvol: Journal of Applied Physics, 1997, 81[12], 8109-11