Comparison of shallow depth profiles of cobalt-implanted Si wafers determined by total reflection X-ray fluorescence analysis after repeated stratified etching and by Rutherford backscattering spectrometry

摘要

Thin and shallow layers of some 50-150 nm were produced by ion implantation of Co ions in Si wafers and afterwards characterized by concentration-depth profiling. Two methods were applied for that purpose: a novel method combining a stepwise wet-chemical etching of an implanted wafer with total reflection x-ray fluorescence spectrometry (TXRF) and the well-known method of Rutherford backscattering spectrometry (RBS) of the original non-etched wafer. The corresponding profiles agree quite well for both methods, demonstrating a high accuracy of both the novel and established method. The characteristic parameters of the profiles, e.g. concentration and depth at the maximum, mean depth, full width at half-maximum and total dose, show relative deviations of only 4-6% between both methods. Such good agreement was ensured by results traceable to SI units: mass, per mass (g g~(-1)) and depth (m). In addition to the accuracy, further figures of merit, such as detection limit and depth resolution, were discussed in order to demonstrate the high effectiveness and analytical potential of the novel method.