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Calibration procedure for quantitative surface analysis by total reflection X‐ray fluorescence
Author(s) -
Torcheux L.,
Degraeve B.,
Mayeux A.,
Delamar M.
Publication year - 1994
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740210305
Subject(s) - x ray fluorescence , calibration , impurity , analytical chemistry (journal) , wafer , calibration curve , certified reference materials , materials science , total internal reflection , silicon , contamination , chemistry , fluorescence , detection limit , optics , nanotechnology , metallurgy , optoelectronics , physics , ecology , organic chemistry , chromatography , quantum mechanics , biology
Total reflection x‐ray fluorescence analysis (TXRF) is a new technique able either to achieve elemental analysis of microquantities deposited on a very flat reflecting surface or to detect very low levels of surface contamination on reflecting substrates like silicon wafers. In this paper we report a calibration procedure to achieve an impurity quantification in the range of one hundredth of an atomic monolayer and below. To reach this goal, it is necessary to distinguish between two types of surface deposits: submonolayer surface atoms and particulate matter deposited onto the reflector surface. We show how these two situations can be differentiated, both theoretically and experimentally. For surface contamination, calibration curves were obtained from nickel submonolayer standards prepared by a method of quantitative contamination. These standards were certified by Rutherford backscattering analysis (RBS). Results show that linear regression is suitable for calibration. For elements other than nickel it is shown that the correlation between TXRF and RBS is good, except for concentrations of <5 × 10 11 atoms cm −2 . This is mainly owing to the difficulty of obtaining certified low contamination levels with RBS. Quantification limits for TXRF analysis are found to be extremely low in comparison to most surface analysis techniques, and TXRF is able to detect metallic impurities like Fe, Ni, Cr, Zn and Cu at ∼2 × 10 10 atoms cm −2 in a short time (1000 s) without any sample preparation.