Effective Dispersion of CMP Slurry Abrasive Particles

摘要

Twelve commercially available chemical mechanical planarization (CMP) slurries were analyzed using a liquid dispersion optical analyzer to measure the Settling Rate (SR) from the turbidity data. Required Minimum Flow Velocities (RMFV) in the distribution loop, to keep the abrasive particles dispersed, were obtained from the slurry handling tests in a vacuum-pressure-dispense slurry delivery system and 200 foot long simulated global distribution loop. Comparison of RMFV and SR data reveals an empirical correlation, which can be used to estimate RMFV from SR data in slurries. These results suggest that most silica slurry abrasives can be kept in dispersion (without any significant settling) by maintaining a RMFV value of ～0.5 ft/sec, whereas a majority of alumina and ceria slurries require 1.5 to 2.5 ft/sec, depending on abrasive concentration and background chemistries.