ISO 17109:2022 pdf – Surface chemical analysis — Depth profiling — Method for sputter rate determination in X-ray photoelectron spectroscopy, Auger electron spectroscopy and secondary- ion mass spectrometry sputter depth profiling using single and multi-layer thin films.
1 Scope This document specifies a method for the calibration of the sputtered depth of a material from a measurement of its sputtering rate under set sputtering conditions using a single- or multi-layer reference sample with layers of the same material as that requiring depth calibration. The method has a typical accuracy in the range of 5 % to 10 % for layers 20 nm to 200 nm thick when sputter depth profiled using AES, XPS and SIMS. The sputtering rate is determined from the layer thickness and the sputtering time between relevant interfaces in the reference sample and this is used with the sputtering time to give the thickness of the sample to be measured. The determined ion sputtering rate can be used for the prediction of ion sputtering rates for a wide range of other materials so that depth scales and sputtering times in those materials can be estimated through tabulated values of sputtering yields and atomic densities. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 14606, Surface chemical analysis — Sputter depth profiling — Optimization using layered systems as reference materials 3 Terms, definitions, symbols and abbreviated terms 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at https:// www .electropedia .org/ 3.1.1 upper plateau region exhibiting intensities higher than 95 % of the maximum intensity of the characteristic signal for that layer and covering more than half the thickness of that layer
4.2 The surface and the interfaces shall be flat and parallel to each other to avoid any distortion of sputter depth profiles. The surface roughness is often measured using atomic force microscopy and the thickness variation using transmission electron microscopy. The surface roughness of sample and the thickness variation of each layer shall be smaller than the sum of the projected range of the sputtering ions and the information depth of the analytical method. 4.3 The thickness of each layer in multi-layer thin films and the thickness of single-layer thin films shall be determined by high resolution cross-sectional transmission electron microscopy, grazing incidence X-ray reflectivity, medium energy ion scattering spectroscopy, or other appropriate methods for which an accurate uncertainty of measurement can be evaluated using relevant references , . 4.4 The number of A/B layer pairs in the multi-layered reference thin films shall be greater than two since profiles of the first layer A and the last layer B shall not be used due to the surface and the final interface transient effects. 4.5 For single-layer thin films, to minimize any likely contamination or surface oxidation problems, materials like SiO 2 on Si and Ta 2 O 5 on Ta which are stable and remain clean or can easily be cleaned are recommended. Guidelines on how to clean thin film surface are available from ISO 18116  and ISO 18117  . 5 Determination of sputtering rate 5.1 Set the sputtering conditions to be those for which the sputtering rates are required. Changes in the sputtering species, the impact energy, and beam current will change the sputtering rates. The sputter depth profiling parameters are optimized according to ISO 14606. NOTE 1 A typical measurement procedure and result of depth profiling measurement with AES, XPS, and SIMS using multi-layered thin films are illustrated in Annex A.