Excess solubility of oxygen in silicon during steam oxidation

1 8O was introduced into float-zone Si wafers during oxidation in H2 18O at temperatures from 600–1240 °C, and the 18O concentration profiles were measured by secondary ion mass spectrometry. The oxygen solubility, as determined from the surface 18O concentrations, was found to be significantly higher in as-oxidized wafers than in post-oxidation annealed wafers. The temperature dependence of the as-oxidized solubility, Sox, can be described by Sox(T)=1.2×1020 cm−3 exp(−0.67 eV/kT), with a higher activation energy of 1.02 eV for the equilibrium solubility. These results are compared with other published oxygen solubility determinations.