In-situ study of platinum reaction with oxygen contaminated silicon layer

Abstract

This work reports the study of platinum silicide formation on reaction with an oxygen contaminated silicon layer. The observed results are potentially a novel approach to use silicide forming metals as a direct contact electrode to the crystalline core-amorphous silicon oxide shell structure of silicon nanowires without the need of hazardous acids, e.g. hydrofluoric acid, which is commonly used during lithography device preparation to remove the oxide shell. The simulation of the in-situ RBS spectra at temperatures above 250 °C showed the reaction of platinum with the oxygen contaminated silicon layer, forming a new layer with a stoichiometry corresponding to the silicide phase containing about 10–15 at.% oxygen (e.g. Pt0.55, Si0.3, O0.15). The presence of oxygen is attributed to the diffusion of its atoms through the silicide layer to the surface. The in-situ XPS data revealed the diffusion of oxygen towards the surface during the reaction of platinum and silicon while in-situ XRD results showed the sequential formation of the Pt2Si and PtSi phases. Therefore, these results present a simple and user-friendly approach applicable in the fabrication of contact structures in the core-shell silicon nanowire based devices.