Usefulness of surfactants in reducing particle adhesion and their effectiveness in cleaning silicon wafers

The effectiveness of surfactants (sodium dodecyl sulfate and dodecyl amine hydrochloride) in the cleaning of silicon wafers has been investigated using atomic force microscopy and image analysis. Recognizing that the surface of SC-1-cleaned silicon wafers is essentially SiO2 atomic force microscopy was used to determine the interaction forces for the silica/silica and silica/alumina systems with and without surfactant present in solution. Experimental force vs. separation distance curves were found to be in good agreement with theoretical predictions based on electrostatic and van der Waals interactions. Interestingly, the pull-off forces obtained from atomic force microscopy measurements were very close to the adhesion forces calculated on the basis of van der Waals interactions at very close separations. The results from image analysis further confirmed the usefulness of surfactants in reducing particle adhesion and their effectiveness in cleaning silicon wafers. Finally, the results from this study suggest that a more complete understanding of particle interaction forces should be of considerable importance to the electronics industry.