Development of a micro-focus x-ray fluorescence spectrometer using multiple target anode monochromatic x-ray sources

A micro-focus x-ray fluorescence spectrometer using an x-ray tube with multiple excitation sources and a doubly curved crystal (DCC) has been developed in this study. The excited target of the x-ray tube can be selected from among Cr, W, and Rh. The focal spot size for the conditions of 30 kV and 0.5 mA was estimated to be about 10 gm in diameter. The doubly curved crystal has von Hamos geometry in the vertical direction and Johann geometry in the horizontal direction. Thin Si(111) was selected as the crystal material. It can focus the W-L beta x-rays into an area of 165.6 mu m x 132.9 mu m as the full width at half maximum for the sample position. The spectrometer combining the present x-ray tube and DCCs was demonstrated to be able to measure an Ni particle 5 mu m in diameter on an Si wafer by W-L beta excitation. The lower limit of detection was estimated to be 7.29 pg, or equivalent to a particle 0.58 mu m in diameter. Copyright (C) 2009 John Wiley & Sons, Ltd.