Quantification in grazing-emission X-ray fluorescence spectrometry

In grazing-emission X-ray fluorescence (GEXRF) spectrometry wavelength-disp ersive detection can be applied. Much softer radiation and hence lighter el ements than in total-reflection X-ray (TXRF) spectrometry can thus be detec ted. We used simulations to investigate methods of quantification of GEXRF results involving soft characteristic radiation. From these studies, it is concluded that for ultra-thin layers, e.g. the sub-monolayer amounts encoun tered in semiconductor contamination analysis, calibration plots are linear . For thicker layers, quantification should be performed very carefully bec ause of deviations from linearity due to absorption of radiation and to osc illations in the calibration curve. These oscillations are caused by interf erence of fluorescence radiation emitted directly towards the detector and radiation reflected at the sample-substrate interface. Suggestions for a ju dicious choice of measurement conditions are made and the benefits of inter nal standardisation are discussed. (C) 1999 Elsevier Science B.V. All right s reserved.