Fundamental Characterization Studies of Condensed Chemical Mechanical Polishing Waste Slurry

We investigated the possibility of efficiently reclaiming fumed silica slurry in an oxide chemical-mechanical polishing (CMP) process in order to reduce the cost of consumables. We demonstrated the feasibility of reclaiming condensed waste slurry for reuse. The reclaimed slurry had a ten-fold increase in number of particles larger than 0.56 um over the original slurry. However, there was significant decrease in the number of particles larger than 1.01um in the reclaimed slurry compared with that in the original one because depth filters used during reclamation effectively remove agglomerated particles and foreign materials from the condensed waste slurry. The removal rate and uniformity of the reclaimed slurry was comparable with original one. Even though there was a slight increase in particles on the wafers, no changes in level of micro-scratches on wafers was observed. Therefore, the CMP performance of the reclaimed slurry is comparable to that of the original one.