Atsushi Yoshinaga

Origins of Spurious Peaks of Total Reflection X-Ray Fluorescence Analysis of Si Wafers Excited by Monochromatic X-Ray Beam W-Lβ

Spurious peaks such as Fe-Kα or Ni-Kα 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-Lβ) 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.

Influence of Standing Waves on Impurity Analysis of Si(001) Wafer Using Commercially Available Total-Reflection X-Ray Fluorescence Analyzer

In the analysis of trace impurities (on the order of 1010 atoms/cm2) on Si wafer surfaces using the commercially available total-reflection X-ray fluorescence analyzer, the X-ray fluorescence radiations are enhanced for the particular incident azimuth at which the evanescence beam penetrating into the Si wafer satisfies the Bragg condition. We investigated whether the enhancement of fluorescence radiation is due to the standing waves formed inside and outside the wafer surface. It is shown, using a sample which is intentionally contaminated with Zn, that the intensity enhancement is not directly connected with this phenomenon.