Sputter-deposited Cr–Si–O Cermet Films by XPS

Abstract

X-ray photoelectron spectroscopy (XPS) was used to characterize thin film of Cr–Si–O cermet, rf sputter-deposited onto a thermally oxidized Si wafer. Angle dependent spectra (θ=0° and 60°) were acquired on both the as received and the Ar+ ion sputtered states. In the as received state the topmost layer is enriched in Si and O; Si and Cr are present in both oxidized and reduced forms. After sputtering by Ar+ (2.5 keV, 6 × 1016 ions/cm2), Cr becomes reduced to Cr0, and the relative amount of Si0 increases substantially (i.e., up to about 40% of total Si). These reduced states are found to recombine to CrxSi-type silicides. The Cr–Si–O layers are applied as precision thin film resistors of good long-range stability with low temperature coefficient of resistivity. Heat treatment—leading to crystalline silicide phase—is used to consolidate the properties of these layers for device applications. We have shown (apparently for the first time), however, that room temperature ion impact can also create highly dispersed—nondetectable by XRD—silicide clusters, the formation of which has been deduced from the Si Auger parameter, being significantly higher for the silicide (aSi=1716.2–1716.5 eV) than for elemental Si (aSi=1716.0 eV).