TRACE-ELEMENT ANALYSIS ON SI WAFER SURFACES BY TXRF AT THE ID32 ESRF UNDULATOR BEAMLINE

Synchrotron radiation total-reflection X-ray fluorescence (SR-TXRF) ha s been applied to the impurity analysis of Si wafers using a third-gen eration synchrotron radiation undulator source. A lower limit of detec tability (LLD) for Ni atoms of 17 fg (1.7 x 10(8) atoms cm(-2)) has be en achieved with an optical set-up based on an Si(111) double-crystal monochromator and a horizontal sample geometry. These first results ar e very promising for synchrotron radiation trace element analysis sinc e we estimate that it is possible to lower the LLD by a factor of abou t 25 by employing appropriate optics and detectors. The use of a cryst al monochromator opens new possibilities to perform absorption and sca ttering experiments (NEXAFS and X-ray standing-wave methods) for chemi cal and structural analysis of ultratrace elements.