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Total reflection X-ray fluorescence analysis (TXRF) offers a nondestructive qualitative and quantitative analysis of trace elements. Due to its outstanding properties TXRF is widely used in the semiconductor industry for the analysis of silicon wafer surfaces and in the chemical analysis of liquid samples. Two problems occur in quantification: the large statistical uncertainty in wafer surface analysis and the validity of using an internal standard in chemical analysis. In general TXRF is known to allow for linear calibration. For small sample amounts (low nanogram (ng) region) the thin film approximation is valid neglecting absorption effects of the exciting and the detected radiation. For higher total amounts of samples deviations from the linear relation between fluorescence intensity and sample amount can be observed. This could be caused by the sample itself because inhomogeneities and different sample shapes can lead to differences of the emitted fluorescence intensities and high statistical errors. The aim of the study was to investigate the elemental distribution inside a sample. Single and multi-element samples were investigated with Synchrotron-radiation-induced micro X-ray Fluorescence Analysis (SR-μ-XRF) and with an optical microscope. It could be proven that the microscope images are all based on the investigated elements. This allows the determination of the sample shape and potential inhomogeneities using only light microscope images. For the multi-element samples, it was furthermore shown that the elemental distribution inside the samples is homogeneous. This justifies internal standard quantification.

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Total reflection X-ray fluorescence analysis (TXRF) is a method for qualitative and quantitative analysis of trace elements. In general TXRF is known to allow for linear calibration typically using an internal standard for quantification. For small sample amounts (low ng region) the thin film approximation is valid neglecting absorption effects of the exciting and the detected radiation. However, for higher total amounts of samples deviations from the linear relation between fluorescence intensity and sample amount have been observed. The topic of the presented work is an investigation of the parameters influencing the absorption phenomenon. Samples with different total amounts of arsenic have been prepared to determine the upper limit of sample mass where the linear relation between fluorescence intensity and sample amount is no longer guaranteed. It was found that the relation between fluorescence intensity and sample amount is linear up to ∼100 ng arsenic. A simulation model was developed to calculate the influence of the absorption effects. Even though the results of the simulations are not satisfying yet it could be shown that one of the key parameters for the absorption effect is the density of the investigated element in the dried residues.

Total Reflection X-ray Fluorescence (TXRF) analysis is a well-established analytical method in the semiconductor industry for the analysis of silicon wafer surfaces. To improve the detection limits of TXRF (given in at cm(-2)) for wafer surface analysis vapor phase decomposition-droplet collection (VPD-DC) is used to collect the impurities of the total surface in one droplet. This leads to higher sample masses to be analyzed than in straight TXRF. In TXRF, absorption effects concerning the excitation and the detected radiation are usually disregarded. This is justified because mostly small sample amounts (pg to ng range) are used and the thin film approximation is valid. For higher total amounts of sample deviations from the linear relation between the fluorescence intensity and sample amount have been observed (saturation effect). These lead to difficulties in quantification with external standard, which is the calibration method used in TXRF wafer surface analysis. The content of the presented work is an investigation of the absorption phenomenon and hence the fluorescence intensity to improve the quantification of TXRF using VPD-DC. Samples with different total amounts of nickel were prepared and the emitted fluorescence intensities were measured at two different excitation energies to estimate the upper limit of sample mass where the relation between the fluorescence intensity and sample amount diverges from linearity depending on the excitation energy. The measurement results were compared to calculations performed with a self-developed simulation model. It could be verified that if the excitation energy is closer to the absorption edge of the excited element (which means better excitation) the saturation effect appears at a lower sample mass