Isotopic substitution of si during thermal growth of ultrathin silicon-oxide films on si(111) in o/sub 2/

Abstract

The transport of Si atoms during thermal growth of silicon-oxide films on silicon in dry O2 was investigated by isotopic substitution of Si. The experiment consisted of depositing a 7.6-nm-thick epitaxial layer of 29Si on a Si~111! substrate and determining the 29Si profiles, with subnanometric depth resolution, before and after oxidation in 50 mbar of dry O2 at 1000 °C for 60 min. The results constitute an experimental confirmation of a widely held belief that Si does not diffuse through the growing oxide to react with oxygen at the gas/oxide interface, leaving O2 as the only mobile species. [S0163-1829~99!10127-9]