Sputter depth profiles of Ni/Cr thin-film structures obtained from the emission of Auger electrons and x rays

Abstract

Multilayered thin-film Ni/Cr/Ni/Cr. . . structures, prepared by sputter deposition, were depth profiled by argon ion sputtering at energies of both 1 and 3 keV. Compositional depth profiles were obtained by simultaneously detecting the characteristic emission of Auger electrons and x rays that results from bombardment with 5-keV primary electrons. An ultra-thin windowed energy-dispersive Si (Li) detector was used to monitor the emitted Lα x rays of Ni(0.85 keV) and Cr(0.57 keV). Due to the use of a near-grazing take off angle for x rays, the x-ray ’’probe depth’’ for 5-keV primary electrons is somewhat greater than the thickness of an individual thin film (∠70 nm) and results in an x-ray profile generated by the amount and type of material contained in such a layer thickness. Both Auger and x-ray measurements indicate that each sputtered film is completely resolved, that little degradation in the interface widths is observed in sputtering through all nine layers of the structure, and that determinations of sputtering times based on Ni/Cr periodicity as well as on single film removal are remarkably consistent. The well-defined repetitive profiles indicate that this multilayered material may be well suited for use in sputter depth calibration. In combining x-ray analysis with Auger spectroscopy, the additional information obtained can be very effective in thin-film analysis.