3-D global routing with layer directive and scenic constraints

As technology advances, modern physical synthesis flows pose layer directive and scenic constraints to global routing. Respecting these constraints in global routing is critical to achieve timing closure. In this paper, we propose a 3-D global routing algorithm which simultaneously respects layer directive constraints and scenic constraints. The routing algorithm is based on iterative ripping-up and rerouting. The core components of the algorithm include a 3-D A* search which strictly obeys given constraints, and a net ordering approach which helps to achieve high-quality routing results. Experimental results demonstrate the effectiveness of the routing algorithm.