A novel method to address ILD CMP non-uniformity issue for advanced memory device integration

CMP non-uniformity has been an increasingly critical issue that needs to be addressed as memory device geometries continue to shrink. This issue is more prominent for ILD oxide CMP due to its poor controllability as compared to other CMP processes that can rely on stopping layers for effective endpoint detections and non-uniformity control. In this paper, we propose a novel approach to address the ILD oxide CMP non-uniformity issue by introducing a dual film polish concept. Experimental results show that this approach improves wafer non-uniformity and reduces scratches. Final device probe yield suggests that the approach is valid. A rate model is also proposed to elucidate the dual film CMP process.