Study on dispersion property of sub-micro -Al2O3 powders in water suspension by physical-chemical process

Sub-micro -Al2O3 polishing liquid is often used as the slurry in chemical mechanical polishing (CMP). At present, water is usually used as dispersion medium to disperse sub-micro -Al2O3 powders, but the sub-micro -Al2O3 powders easily subside in aqueous solution. In previous studies, researchers usually used single method to disperse superfine powders, however, the dispersion effect was non-ideal. In order to solve the difficult problem of sub-micro -Al2O3 powders dispersed in water suspension, firstly, using physical method, the effects of milling time, ultrasonic time on the dispersion property of sub-micro -Al2O3 powders in water suspension was studied by single factorial test. Then, using chemical method, the effects of dispersant type, dispersant concentration and pH value on the dispersion property of sub-micro -Al2O3 powders in water suspension was studied by orthogonal test. Absorbance was used to evaluate the dispersion property of sub-micro -Al2O3 powders. The results show that the optimal dispersing conditions are milling time 60min, ultrasonic time 20min, mass percent concentration of STPP 1% and pH value 9.