Electrostatic Removal of Particle Singlets and Doublets from Conductive Surfaces

Abstract

Fine particles can cause significant losses during the manufacture of microelectronic components. Removal of such deposited particles is important in reducing such losses. The repulsive force on a singlet conducting particle on a charged conducting surface is theoretically proportional to the particle area and the square of the electric field. We have removed particles as small as 1 μm by creating high (> 100 kV/cm) electrostatic fields at the surfaces of conductors. We found that members of doublet pairs had removal probabilities (at the same field strength) that were less than the removal probability of singlets. Further, the removal of one pair member made more probable the removal of the other. Likely factors are the adhesion of the particles to each other and the increase in adhesion to the surface resulting from the attraction of each particle to the image charge of the other. The theoretical analyses explain why whole chains of particles were found to be removed under conditions where the probability of the removal of a singlet particle was relatively small.