An efficient over-the-cell channel router

An approach for over-the-cell channel routing in the standard cell design style is proposed. This approach uses a two-layer routing model where channel is divided into zones. Each zone has a zone density and a pseudo zone density. In the proposed algorithm, the removal of any subnet from a zone reduces pseudo zone density by one, but only the removal of all subnets of a net from a zone contributes to the reduction in channel density. Besides the above heuristics, techniques such as net (pin) shifting are applied to the routing problem to further reduce channel height. Experimentally, the approach reduces more channel density than previous researches and can speed up the process of over-the-cell routing