Depth analysis of buried iron disilicide formation by Fe ion implantation into Si

Abstract

The depth distribution of the iron disilicide phases (α-FeSi2 and β-FeSi2) was investigated nondestructively by depth-selective conversion-electron Mössbauer spectroscopy after Fe+ implantation (200 keV, 3×1017 cm−2) and after subsequent rapid thermal annealing (RTA) at 900 °C for 30 s. The depth profiles of the two phases were found to be correlated with the Fe concentration profiles as determined by Auger electron sputter depth profiling. For the as-implanted state a broad distribution of a phase mixture of α- and β-FeSi2 is observed. Subsequent RTA induces a layered structure including a buried β-FeSi2 layer with a high phase content of 90% near 220 nm.