A standard cell global routing algorithm with net selection for over‐the‐cell routing

Abstract

AbstractIn the detailed routing for VLSI standard cell layout design, the over‐the‐cell channel routing, which utilizes the over‐the‐cell region as the routing region, has been proposed. In this design method, after determining the net assignment to each channel in the global routing step, the track assignment both in channel and on over‐the‐cell regions is performed by an over‐the‐cell channel router. However, conventional global routing algorithms do not assume over‐the‐cell channel routing but conventional channel routing. Therefore, the minimization of channel density does not always successfully lead to the minimization of the final channel height.This paper presents a new global routing method for standard cell layouts to determine global routes for each net in both channel and over‐the‐cell regions simultaneously. the standard cell layout design system GLORIA based on the proposed algorithm is developed, and the experimental results compared with the conventional global routing method that performs the over‐the‐cell channel routing after global‐routing with Timber Wolf‐SC4.2c are reported.Experimental results showed that the proposed routing algorithm can route about 18.4 percent fewer number of tracks than the conventional routing method, and the effectiveness of the proposed method is shown. the experimental results of applying the proposed method to the three‐layer routing layout model also are presented.