Ion beam sputtering techniques for high-resolution concentration depth profiling with glancing-incidence X-ray fluorescence spectrometry

The application of ion beam sputtering in combination with glancing-incidence X-ray fluorescence spectrometry for high-resolution concentration depth profiling is presented. Two new techniques are described: first, in the ''bevel-etching technique'', the sample depth profile is uncovered on the sample surface either by sputter etching with a gradient of the ion beam intensity or by varying the sputtering time by moving a shutter in front of the sample; second, in the ''deposition technique'', samples are etched uniformly and the sputtered material is deposited on a moving substrate. The bevelled sample and also the material deposited on the substrate are characterized (laterally resolved) by glancing incidence X-ray fluorescence spectrometry. The apparatus and techniques are described in detail. Typical experiments showing the advantages of and problems with the two techniques are discussed. The achievable depth resolutions, 1.5 nm with the bevel-etching technique and 1.4 nm with the deposition technique, are comparable with the best results from other depth profiling methods. (C) 1997 Elsevier Science B.V.