Spectroscopic Studies of the Effect of Sputter Etching on beta-FeSi2 Film Growth

Abstract

This study aims to better understand the surface modifications created byan in situ surface etching process applied with a neutral molecule source prior to ironcoating which made it possible to grow beta-FeSi2 films on Si substrates without anyfurther heat treatment. The n and p- type Si substrates were sputter-etched by aneutral molecule source, using Ar molecules, before they were coated. This processcaused surface defects, thus provided faster diffusion of the iron (Fe) into the silicon(Si). The sputter-etched Si (100) and (111) substrates were then investigated byFourier transform infrared (FTIR) spectroscopy in order to clarify the effects ofsurface etching. The IR transmittance spectra showed a decrease in intensity in thesilicon bands after the etching process. The beta-FeSi2 thin films were prepared byunbalanced magnetron sputtering on sputter-etched Si (100) and Si (111) substratesat ambient temperature. The deposition of iron on the etched silicon surfaces resultedin the formation of beta-FeSi2 which was clearly indicated by X-ray diffraction andRaman analysis. After the deposition of Fe and formation of beta-FeSi2 an increasedtransmittance in the Si band region was observed on the FTIR spectra and the peaksbelonging to Si–Si and Si–O–Si vibration bands were reversed after the irondeposition.