Study on the effect of ceria concentration on the silicon oxide removal rate in chemical mechanical planarization

Abstract The effect of ceria concentration on the removal rate of silicon oxide via chemical mechanical planarization was investigated. The removal rate decreased with increasing abrasive concentration. Surface analysis was used to confirm adsorption of ceria particles on silicon oxide wafers. A wide adsorption layer was formed on the wafer surface with ceria abrasive of both positive and negative charges. This adsorption layer was widened with increasing ceria concentration. Silica CMP did not show a decrease of removal rate and showed only a small area of adsorption. It was confirmed that adsorption of these ceria particles is caused by applied pressure as well as the effect of electrostatic force. It was confirmed through particle size distribution analysis of the slurry waste that the largest number of activated particles was achieved at 0.5 wt% concentration. The mechanism of effect for ceria concentration vs. removal rate is suggested with a schematic. Understanding of adsorption between ceria and silicon oxide, understood from various perspectives, will be helpful in further investigation of post CMP cleaning processes as well as CMP processes.