Interaction forces between oxide and silica-modified terpolymer abrasives and their impact on CMP and post-CMP

摘要

Colloidal AFM was used to perform adhesion force measurements between a silica surface and polymer and silica-modified composite abrasives in DIW and buffer solutions at pH 4 and 10. We found that the pull-off forces for all the particles increase with decreasing pH. This effect is more evident in the case of the polymer colloids that are positively charged for pH below neutrality due to the presence of surface amino groups. The post-CMP particle removal efficiency after brush scrubbing in dilute ammonia is lower for the polymer particles. The relative density of the polymer particles on the oxide surface after CMP decreases with increasing pH. Furthermore, in the buffer solution at pH 10 we observe the highest RR due to the higher dissolution rate of the silica in alkaline pH.