Abstract
CMP slurries were filtered by porous membrane filters of various materials to investigate the effect of surface property on filterability. All the filtrates not depending on the membrane materials showed reduction of abrasive particle concentration followed by immediate recovery at filtration startup. A mechanism of the results would be (a) significant amount of adsorption of abrasive particles at startup, (b) restraint of capture of additional abrasive particles by repulsion between adsorbed particles and dispersed particles. The mechanism indicates that naked surface property of the membranes would have no effect on filterability; instead property of adsorbed abrasive particles would dominate whole filtration process. The adsorption of abrasive particles was found to cause a significant increase and deviation of initial delta P. Pretreatment of the membrane filters with capturing small amount of abrasive particles was effective to restrain the increase and deviation of initial delta P.
