Accuracy of the non-destructive surface nanostructure quantification technique based on analysis of the XPS or AES peak shape

摘要

The accuracy of XPS and AES quantification by peak shape analysis was established from a detailed analysis of a range of model spectra and three sets of experiments. It was found that information on the concentration-depth profile in the surface region up to depths of similar to 5 lambda(i) (where lambda(i) is the inelastic electron mean free path) is primarily contained in the spectral energy region up to similar to 100 eV below the peak energy and is essentially completely contained by the energy region up to similar to 200 eV below the peak. Analysis of a larger energy range than 100 eV does not add much to the information on the details of the structure in the outermost 5 lambda(i) but gives the possibility to determine additional structural parameters that describe the composition at larger depths. The structural parameters that describe the chemical composition of the outermost 5-10 lambda(i) of the solid were divided into primary and secondary parameters: the primary parameters are the three most important parameters needed to describe the main characteristics of the distribution of atoms; the secondary parameters are parameters other than the three primary parameters that describe the finer details of the depth distribution of atoms in the outermost 5-10 lambda(i) of the surface region. The uncertainty in the determined three primary parameters is typically 5-10%. The uncertainty in the determined secondary parameters is typically greater than or similar to 35%. Different models of depth profiles can be distinguished when they differ significantly over a width of more than similar to 1/3 lambda(i) at any depth less than or similar to 5 lambda(i). The uncertainty in the total determined amounts of atoms within the surface region is similar to 5-10% as long as the depths are within the primary probing depth of the method (i.e. <5 lambda(i)). The absolute quantification of a set of samples where the in-depth distribution varies considerably gives a root-mean-square scatter of 15%, This is reduced to similar to 10% when elastic scattering effects are modelled by a simple analytical expression. (C) 1998 John Wiley & Sons, Ltd. [References: 73]