THE ADHESION-INDUCED DEFORMATION AND THE REMOVAL OF SUBMICROMETER PARTICLES

Adhesion-induced deformations of submicrometer polystyrene particles on silicon substrates were observed as a function of time using scanning electron microscopy. The contact area between the particle and the substrate was found to increase with time for a period of approximately 72 hours before reaching a constant value. The ratio of the final contact radius to the particle radius was almost-equal-to 0.4. The time dependence of this deformation appears similar to the creep phenomenon in bulk polymers. These results are related to the studies of particle removal conducted for different time periods, using hydrodynamic and centrifugal removal forces. The removal efficiency was found to decrease with time. This correlates well with the increase in the adhesion force on the particles with time as observed from the SEM measurements. The effect of the particle diameter on the removal efficiency and the correlation between the time dependent adhesion-induced deformation and particle removal efficiency is discussed.