LOW-TEMPERATURE IRON THIN-FILM SILICON REACTIONS

Low temperature reactions between Fe thin films and Si substrates have been studied. Iron films were deposited by electron beam evaporation onto [111] orientated Si substrates. An SiO2 capping layer was used to protect the Fe from oxidation during subsequent annealing. Samples we re annealed at temperatures as high as 650 degrees C, for up to severa l hours. It has been shown that FeSi is the initial silicide to form, with 300 degrees C being the lowest formation temperature. Fe3Si forms after most of the Fe has been consumed, and forms as a separate phase from alpha-Fe and not through a disorder-order transformation. Micros tructural evidence for nucleation controlled formation of beta-FeSi2 f rom FeSi has also been given.