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In metallic contamination analysis of semiconductor wafers, preconcentration methods such as vapor phase decomposition–droplet collection VPD-DC or droplet sandwich etch DSE are combined with sensitive analytical techniques, often total-reflection X-ray fluorescence spectrometry TXRF. Previously we have reported about the occurrence of TXRF saturation effects in the analysis of microdroplet residues from these methods and identified the origin as a mass-absorption effect of primary X-rays. In this study, different approaches to deal with TXRF saturation effects in semiconductor applications are evaluated. Corrective approaches are tested for the application of VPD-DC-TXRF on Si wafers. The application of correction factors resulted in an overestimation of the effect of 20. Internal standardization approaches did not perform well because of the separation of the internal standard element apart from the analytes during the drying step. We suggest another internal approach using the intensity of scattered primary X-rays as an indicator for accuracy.The parameters in a Ge matrix removal method have been investigated. The application of the method on samples from the DSE method on spin coated Ge wafers resulted in efficiencies at 100 compared to only 40 without matrix removal. Finally, the use of nanoliter deposition or ink-jet spray methods is proposed to extend the dynamic range of TXRF on microdroplet residues. This suggestion is motivated with calculations based on a mass-absorption model and with experimental results from the study of linearity of TXRF on Ni spin coated Si wafers and the related morphology of the surface species.

In semiconductor manufacturing, potential wetting issues with aqueous chemistries are becoming a concern as feature dimensions are continuously scaled down and novel materials with different wetting properties are introduced in new technology nodes. The wetting behavior of silicon nanopillars with different dimensions and surface modifications has been studied using static contact angle, decoration by etching, and attenuated total reflection infra-red spectroscopy (ATR-FTIR). The contact angle measurements showed a consistent deviation from the classic wetting models for patterned substrates with an hydrophilic surface termination. Under these conditions the decoration and ATR-FTIR studies gave evidence for partial wetting, with residual gas lasting for more than 30 min. It is proposed that this was resulting from the formation of long-lasting surface nanobubbles localized in-between or at the bottom of nanopillars. On the other hand the residual gas volume estimated by ATR-FTIR seemed too small to explain the contact angle deviations. It is proposed that the apparent extension of the superhydrophobic regime to lower contact angles resulted from modifications of the wettability of the surface of nanopillars caused by the manufacturing process. Both the formation of nanobubbles and the extension of the superhydrophobic regime may present challenges for aqueous cleaning in semiconductor manufacturing.