Correlation of non-visual defects at post copper CMP to yield critical physical defects at next metallization layer

The NVD inspection system detected radial “streak” like NVDs at the post Cu CMP clean process that were not detected by the optical inspection system. Layer to layer overlay of the NVD defect maps from the current Cu CMP layer with the optical defect maps from post nitride deposition and the next copper interconnect level revealed that the NVDs were truly the root cause of the yield critical defect issue.