A general multi-layer area router

This paper presents a general multi-layer area router based on a novel grid construction scheme. The grid construction scheme produces more wiring tracks than the normal uniform grid scheme and accounts for differing design rules of the layers involved. Initial routing performed on the varying capacity grid is followed by a layer assignment stage. Routing completion is ensured by iterating local and global modifications in the layer assignment stage. Our router has been incorporated into the Custom Cell Synthesis project at MCC and has shown improved results for cell synthesis problems when compared with the router Mighty which was used in earlier versions of the project.