Detection limits of trace elements for wavelength dispersive total X-ray fluorescence under high flux synchrotron radiation

The performance of wavelength dispersive (WD) total reflection X-ray fluorescence (TXRF) equipment in conjunction with the high flux quasi monochromatic X-ray of beamline 40XU at the synchrotron radiation (SR) facility SPring-8 has been explored. To obtain a good detection limit for the trace elements, the origin of background events has been studied and we found that the main part of the background is generated in the substrate, presumably by the photoelectron bremsstrahlung. The optimization of the grazing angle of the incident X-ray has been carried out to minimize the background signals in addition to maximizing the fluorescence signals to obtain a good lower limit of detectability (LLD). We evaluated the LLD for light through heavy elements. We obtained the LLD of 5.0 x 10(8) atoms /cm(2) for Ni with the energy resolution of 50eV. Furthermore, by applying the surface concentration technique for an 8 inch Si wafer, we achieved the Ni LLD of 3.7 x 10(6) atoms/cm(2) for the first time, which is lower than the LLD obtained from chemical analysis such as inductively coupled plasma-mass spectrometry (ICP-MS).