Accuracy of Total Reflection X-Ray Fluorescence Spectrometry near the Detection Limit

Total reflection X-ray fluorescence spectrometry (TXRF) is one of the most common tools to analyze metal contaminants on silicon wafers and other substrate surfaces. Although the detection limit of commercial TXRF was improved to the concentration region of 10⁹toms cm^-2, its accuracy at low concentration was not yet clarified until now. In this paper, we examine the accuracy of the quantitative analysis by TXRF under 10¹¹ atoms cm^-2 for Fe, Ni, Cu and Zn. In particular, four factors (standard sample, reference analyzing method, compensation of spurious peak and peak separation) are considered. Under a controlled condition, the accuracy is within 20% as compared with atomic absorption spectrophptometry (AAS).