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Density–depth profiles of an As‐implanted Si wafer studied by repeated planar sputter etching and total reflection x‐ray fluorescence analysis

The implantation of a high dose of high‐energy ions into an Si wafer causes amorphization of the original monocrystalline structure within a near‐surface layer. The in‐depth distribution of both Si atoms of the wafer and As ions implanted at a dose of 1 × 1017 ions cm−2 and an energy of 100 keV is studied. A novel method combining a repeated planar and broad sputter etching with differential weighing, surface analysis by total reflection x‐ray fluorescence and Tolansky interferometry is used for this investigation. Different depth profiles are recorded on the nanometre scale for the concentration defined as the mole ratio of As and Si, for the mass density of the implanted layer and for the number density of As and Si. The results generally correspond with measurements of Rutherford backscattering spectrometry and only deviate when the assumptions made for the mass density do not fit well. An appropriate approach to this quantity involves the number density of implanted ions but, furthermore, considers a variation of the number density of Si atoms during implantation, especially for a high dose and high‐energy implantation. The variation can be taken into account by a factor γ, where γ > 1 indicates compression and γ < 1 indicates extension of the original crystalline structure. For the above mentioned implantation, γ is measured separately for each sublayer to obtain accurate depth profiles. Copyright © 2003 John Wiley & Sons, Ltd.