Silicon transport during oxidation

We have investigated the transport of silicon across the silicon/silicon dioxide boundary, in the light of recently proposed reactive layer models of silicon oxidation. Using sequential 18O2-enriched and natural oxygen gas oxidations at 600, 850 and 950°C we have placed an upper limit of ∼0·2 of a monolayer on the distance silicon diffuses into the oxide during oxidation. Thus the formation of new oxide occurs essentially at the silicon/silica interface.