Quantitative Analysis of Surface Contaminations on Si Wafers by Total Reflection X-Ray Fluorescence

A total reflection X-ray fluorescence (TRXRF) technique has been recently used to analyze metal contaminations on Si wafers. In this work, microdrop-contaminated Si wafers are used to make the calibration curves. Metal impurities in these wafers are shown to be condensed in a very small area near the center of the dropped area. To make the calibration curve, a relationship is derived between the intensity of the characteristic X-ray from metal impurities in the condensed area and that from the impurities uniformly distributed over the wafer surface. On the basis of this relationship, calibration curves for Fe, Ni, Cu and Zn are obtained.