In this work, we developed a mathematical model to quantify the translation of soluble contaminants from bulk liquid chemicals to the surface of wafers during spin coating. We tested various kinds of liquids, including those used in application of photo-resist as well as wafer cleaning and surface preparation. To validate the model, dilute polymer solutions with different concentrations were deposited onto spinning wafers, where they flowed outward and then evaporated. We used ellipsometry to determine the mass of: contaminant left behind on the wafers. The levels of deposited contaminants increased with concentration in the bulk liquid and decreased with spin speed. The model well predicted the experimental data and thus allows for estimation of contaminant translation during spin coating.
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