Rhodium and silicon system: II. Rhodium silicide formation

Abstract

Detailed characterizations of rhodium/silicon films prepared by co-deposition using magnetronsputtering have been carried out on silicon substrates at room temperature up to900 °C. The properties of the films were investigated using XPS/UPS, XRD, SIMS, SEM andAFM techniques. It should be emphasized that XPS/UPS measurements are carriedout without breaking the vacuum to avoid any contamination of the film. Up to500 °C an interdiffusion between the oxidized silicon wafer and the depositedRh/Si film occurred leading to hole formation in the entire film at900 °C. Diffraction patternsfor the compounds Rh2Si, Rh5Si3, RhSiand Rh3Si4 were measured. Upon annealing the covalent character is increased and for thesamples forming the compound RhSi the valence band structure is markedlychanged. Depth profiling (XPS and SIMS) reveals a stable composition in thebulk of the film. For these measurements the silicon-rich alloy in the interfaciallayer is probably an effect of sputtering, by implanting the Rh atoms intothe silicon substrate. A previously reported negative shift for the compoundRh5Si3 could be connected to the sample preparation, as sputtering of the surface isreducing the silicon content and inducing a glassy state. For the first phaseRh2Si formed on the rhodium-rich side the shift in binding energy is unclear, for all the othercompounds encountered in this work a positive shift relative to pure rhodium was found.