Mechanisms of contaminant particle production, migration, and adhesion

Abstract

Three fundamental processes associated with particulate contamination of manufacturing processes are particle generation, migration, and adhesion. A more complete understanding of each of these processes, and their interactions, can aid in efforts to eliminate product contamination and thereby increase product yields. We present results of particle generation studied in the context of mechanical wear. The production of airborne particles from the wear of stainless-steel components is examined. The results indicate that submicron particles dominate the particle population in terms of number of particles generated. The migration and deposition of submicron particles under clean room conditions is described, with reference to a deposition model that includes particle diffusion effects. Experimental results of particle deposition in a clean room are compared to the model. Measurements of the adhesion under vacuum of dry-deposited particles of known size and composition are also presented. These show qualitative agreement with a model having a linear dependence of adhesion on particle diameter. The results are discussed in the context of increased automation in product handling and more stringent product isolation. © 1988, American Vacuum Society. All rights reserved.