Formation of interfacial iron silicides on the oxidized silicon surface during solid-phase epitaxy

Abstract

The early stages of iron silicide formation in the Fe/SiOx/Si(100) ternary system during solid-phase epitaxy are studied by high-resolution (∼100 meV) photoelectron spectroscopy using synchrotron radiation. The spectra of core and valence electrons taken after a number of isochronous heat treatments of the samples at 750°C are analyzed. It is found that the solid-phase reaction between Fe and Si atoms proceeds in the vicinity of the SiOx/Si interface, which metal atoms reach when deposited on the sample surface at room temperature. Iron silicide starts forming at 60°C. Solid-phase synthesis is shown to proceed in two stages: the formation of the metastable FeSi interfacial phase with a CsCl-like structure and the formation of the stable β-FeSi2 phase. During annealing, structural modification of the silicon oxide occurs, which shows up in the growth of the Si+4 peaks and attenuation of the Si+2 peaks.