Trace element analysis on Si wafer surfaces by TXRF at the ID32 ESRF undulator beamline

Abstract

Synchrotron radiation total-re¯ection X-ray¯uorescence (SR-TXRF) has been applied to the impurity analysis of Si wafers using a third-generation synchrotron radiation undulator source. A lower limit of detectability (LLD) for Ni atoms of 17 fg (1.7 Â 10 8 atoms cm À2 ) has been achieved with an optical set-up based on an Si(111) double-crystal monochromator and a horizontal sample geometry. These ®rst results are very promising for synchrotron radiation trace element analysis since we estimate that it is possible to lower the LLD by a factor of about 25 by employing appropriate optics and detectors. The use of a crystal monochromator opens new possibilities to perform absorption and scattering experiments (NEXAFS and X-ray standing-wave methods) for chemical and structural analysis of ultratrace elements.

Background spectrum of synchrotron radiation‐excited total reflection x‐ray fluorescence for Si wafer analysis

“…The total Compton scattered counts were calculated by using Eqns (1) and (2) and the x-ray intensity distribution in the SiO 2 layer and Si wafer was computed by using the transfer matrix. 10 Figure 2 shows the variation of total Compton scattered counts as a function of glancing angle and SiO 2 layer thickness.…”

“…Under this condition, Ortega et al regarded Compton scattering as the limiting factor for the determination of Cu and Zn. 2 In this study, we evaluated the absolute counts of background spectra for the whole energy range under given experimental conditions for SR-TXRF measurements of Si wafer surfaces. The theoretical results were compared with measured spectra.…”

Synchrotron RadiationX‐Ray Fluorescence Spectrometry

“…Configuration (a) allows a large solid angle, (114 -116) while (b) is suitable for the measurement of the angular dependence of XRF intensity and is easy to handle the sample. (117) The detection limit obtained was on the order of 10 7 atoms cm −2 , (118) which was an order of magnitude better than that of the laboratory instrument. X-ray absorption spectroscopy for chemical speciation at trace levels was performed to study the origin of the contamination.…”

Use of highly energetic (116 keV) synchrotron radiation for X-ray fluorescence analysis of trace rare-earth and heavy elements

“…The primary characteristics of the thirdgeneration light sources are their extremely high brilliance and the availability of high-energy X-rays. The former characteristic is already well appreciated in relation to the construction of X-ray microscope systems with a beam size of less than 1 µm (Snigirev et al, 1995;Kagoshima et al, 2000) and that of a TXRF system with fg sensitivity (Wobrauschek et al, 1997;Ortega et al, 1998;Sakurai et al, 2001). However, the utilization of high-energy X-rays from third-generation light sources in XRF analyses has remained a challenge.…”