Wire Density Driven Global Routing for CMP Variation and Timing

In this paper, we propose the first wire density driven global routing that considers CMP variation and timing. To enable CMP awareness during global routing, we propose a compact predictive CMP model with dummy fill, and validate it with extensive industry data. While wire density has some correlation and similarity to the conventional congestion metric, they are indeed different in the global routing context. Therefore, wire density rather than congestion should be a unified metric to improve both CMP variation and timing. The proposed wire density driven global routing is implemented in a congestion-driven global router (M. Cho and D. Z. Pan, 2006) for CMP and timing optimization. The new global router utilizes several novel techniques to reduce the wire density of CMP and timing hotspots. Our experimental results are very encouraging. The proposed algorithm improves CMP variation and timing by over 7% with negligible overhead in wirelength and even slightly better routability, compared to the pure congestion-driven global router (M. Cho and D. Z. Pan, 2006)