TXRF Analysis of Low Z Elements and TXRF-NEXAFS Speciation of Organic Contaminants on Silicon Wafer Surfaces Excited by Monochromatized Undulator Radiation

摘要

Total reflection X-ray fluorescence analysis (TXRF) using monochromatized undulator radiation from the synchrotron radiation facility BESSY II has been employed to investigate light element impurities on silicon wafer surfaces. Dedicated droplet samples on silicon wafer surfaces were prepared and for the TXRF arrangements employed lower limits of detection (LOD) for C, N, Na, Mg and Al ranging from 0.3 pg to 1.3 pg. Calculated vapor phase decomposition (VPD) detection limits, derived from the assumption that the sample droplets would have been collected from a 200 mm wafer, range from 2 10~7 atoms / cm~2 to about 10~8 atoms / cm~2 for Na, Mg and Al. Using a thin window Si(Li) detector, the resonant Raman scattering effect limiting the LOD of Al at trace le-vels was studied and an initial LOD value for B was found to be 7 ng. In addition, a TXRF investi-gation of only a few nm thick C-Ni-C structure deposited on a wafer could be performed. In a near edge X-ray absorption fine structure (NEXAFS) investigation in conjunction with TXRF analysis several organic contaminants on silicon wafer surfaces were studied with respect to their speciation.