ORIGINS OF SPURIOUS PEAKS OF TOTAL-REFLECTION X-RAY-FLUORESCENCE ANALYSIS OF SI WAFERS EXCITED BY MONOCHROMATIC X-RAY-BEAM W-L-BETA

Spurious peaks such as Fe-Kalpha or Ni-Kalpha radiations are observed in the analysis of trace metallic impurities on a Si wafer by monochromatic total reflection X-ray fluorescence. These peaks seriously influence the accuracy in the quantitative analysis of the trace impurities. Intensities of these peaks are shown to depend on the intensity of the elastically scattered primary beam (W-Lbeta) whose intensity varies with the incident azimuth. It is found that impurity radiations are included in the primary X-ray beam, and contaminations in the Be window of the X-ray detector are also a source of spurious peaks. The impurities deposited on the Be window, in and/or on the Si(Li) crystal of the detector and the casing material of the X-ray detector can also contribute to these spurious peaks.