Optimizing post cleaning of Tungsten contact CMP to improve the yield of logic products with copper interconnect

Higher yield loss caused by Ml-bridge was found in sub 130nm logic products with multi-level copper interconnect. With the help of FIB, SEM and EDX, the organic surface particle induced during W CT-CMP was considered to result in the Ml-bridge, and then the mechanism of the Ml-bridge was analyzed. Through partition check on post CMP cleaner to reduce the organic particle contamination, it was found that Brush 2 with HF spraying and closed mechanical scrubbing directly induced the organic surface particles, so the Brush 2 was optimized to be open. In addition, combined to optimizing on Mega tank and Brush 1, the defect count was effectively reduced for W CT-CMP, and thus the yield on 130nm logic products were verified to be improved greatly