Direct removal of ultrafine surface contaminants using polymeric brushes with controlled pore sizes

<!-- START_ABSTRACT --> <p> In integrated device manufacturing, the demand for ultrafine polished surfaces without defects continues to increase as the device geometries scale down. Residual particles remaining on wafer surfaces after abrasive polishing can lead to considerable yield losses, especially as nanoscale contaminants increasingly act as killer defects in advanced devices. Polyvinyl alcohol (PVA) brushes, characterized by their soft, flexible, and porous nature, are widely adopted after surface polishing to remove such contaminants via direct contact with the substrate. However, when it comes to removing ultrafine particles smaller than a micrometer, conventional brushes exhibit much lower cleaning efficiency, limited by the length scale of their pore structures. To address this challenge, we first study the correlation between brush pore size and particle removal efficiency based on contact mechanics theory. The model suggests that brushes featuring reduced pore sizes possess high density of surface asperities, therefore enhancing the probability of physical contact with the contaminants. Furthermore, the removal force generated by the finer-pored brush is more likely to exceed the detachment threshold of surface particles. To realize the downsized porous PVA brush, we employed sodium chloride particles as the sacrificial material during PVA brush synthesis which allows miniaturized pore sizes down to 12.5 μm. Experiments using particles ranging from tens of nanometers to several micrometers validate the model’s predictions and demonstrate that downsizing brush pores from a hundred micrometers to tens of micrometers significantly improves the removal efficiency, particularly for submicron particles, where the effect of pore scale becomes increasingly dominant. This research contributes to a deeper understanding of physical particle removal mechanisms in brush scrubbing and provides practical insights for designing pore-scale-optimized brushes that enhance cleaning performance, minimize surface defects, and ultimately support yield enhancement in future integrated 3D device manufacturing. </p> <!-- END_ABSTRACT --> <!-- START_TEMPLATE --> <ul> <li> Source: </li> <li> Tags: </li> </ul> <!-- END_TEMPLATE -->