Capability and efficiency of droplets in removing nanoparticle contaminants from Si wafer via high-speed microdroplet impaction.

The high-speed impact of liquid microdroplets has emerged as a promising method to eliminate nanoparticle contaminants from semiconductor wafer surfaces. However, existing experimental studies have primarily focused on evaluating their own nozzles for removing particles larger than 50 nm, which does not align with the current research roadmap where the target particles' size decreases down to sub-10 nm. As it is more challenging to remove smaller particles, there is a strong need to better understand droplet's spreading behavior in relation to the detachment of particles from a surface. Nonetheless, there remains a lack of experimental evidence to validate existing models or a scarcity of numerical simulation studies, mainly due to the practical difficulties associated with single droplet experiments. Hence, in this study, we conduct a series of numerical simulations to investigate the time-dependent spreading behavior of the droplet, together with collecting local velocity data at the attached particle position. The local velocity data is then integrated to an existing model to predict the effective cleaning diameter for each impact condition. Starting from the free-fall dropwise impaction, we develop a single-microdroplet cleaning system by minimizing the number of sprayed droplets and capturing their behavior using a high-speed camera (HSC), with aims of validating the model predictions and numerical simulations. Finally, we provide a contour plot for a prior prediction of the effective cleaning diameter from the impaction conditions of microdroplets. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]