O-18 TRACER STUDY OF THE PASSIVE THERMAL-OXIDATION OF SILICON

This work focuses on the thermal oxidation of silicon near 1273 K using the double-tracer oxidation method. The results confirm that oxidation occurs by the transport of electrically neutral non-network oxygen through the interstitial space of the vitreous silica (ν-SiO2) scale. Simultaneously, self- (or isotopic-) diffusion occurs in the network, resulting in characteristic isotopic fraction distributions near the gas-scale interface. The self-diffusion coefficients calculated from these profiles agree with those reported for tracer diffusion in ν-SiO2, and the diffusion coefficient calculated from the scale growth is consistent with reported O2 permeation data. An important parameter that describes the double-oxidation behavior is the ratio of the value of Δ/√(Dnt′), where Δ is the scale thickness grown during the second oxidation, Dn is the network self-diffusion coefficient for oxygen, and t′ is the time of the second oxidation. © 1987 Plenum Publishing Corporation.