A Novel Wire-Density-Driven Full-Chip Routing System for CMP Variation Control

As nanometer technology advances, the post chemical-mechanical polishing (CMP) topography variation control becomes crucial for manufacturing closure. To improve the CMP quality, dummy-feature filling is typically performed by foundries after the routing stage. However, filling dummy features may greatly degrade the interconnect performance and significantly increase the input data in the following time-consuming reticle enhancement techniques. It is, thus, desirable to consider wire-density uniformity during routing to minimize the side effects from aggressive post-layout dummy filling. In this paper, we present a new full-chip grid-based routing system considering wire density for reticle planarization enhancement. To fully consider a wire distribution, the router applies a novel two-pass top-down planarity-driven routing framework, which employs new density critical area analysis based on Voronoi diagrams and incorporates an intermediate stage of a density-driven layer/track assignment based on incremental Delaunay triangulation. Experimental results show that our methods can achieve a more balanced wire distribution than state-of-the-art works.