Non-Manhattan maze routing

The availability of multiple metal layers in modern IC processes raises the possibility of using non-Manhattan routing on some of the layers in order to reduce the average interconnect length, and thus improve performance and routability. In this paper, we present novel algorithms for both Manhattan and non-Manhattan multi-layer maze routing. The algorithms in principle can be extended to an arbitrary number of layers, but the paper focuses on four-layer routing, two in horizontal and two in vertical directions for Manhattan, and one layer each in horizontal, vertical, 45-degree and 135-degree directions for non-Manhattan routing. The non-Manhattan algorithms show an improvement of up to 12.2% in average wire length compared to Manhattan routing for two general MCNC benchmarks.