Qualification of a ceria slurry reclaim system for shallow trench isolation polish in high volume manufacturing

Ceria slurry used for polishing semiconductor wafers at the shallow trench isolation step has become very expensive. To help reduce wafer processing costs, a ceria slurry recycling process was developed using a reclaim unit from HighQ-Factory. Product wafers polished with a blend of the concentrated spent slurry and virgin ceria slurry produced equivalent post polish silicon nitride and oxide thicknesses to the standard 2-step, 2-slurry process. Microscratch defects were also reduced by 35% compared to wafers polished with the standard process. Based on the blending ratio, slurry costs were reduced by >50%.