RSMT construction algorithm based on Congestion-Oriented Flexibility

As complexity of VLSI circuits grows, routability has been one of the key factors considered by tree construction algorithms in global routing. Flexibility is a geometric structural property of rectilinear Steiner minimal tree (RSMT), and it is expected to accord with routability and therefore predict the overflow situation. Reference [9] proposed a new definition of flexibility of RSMT, combining RSMT's original flexibility and genetic flexibility, and proved the efficiency of predicting routability utilizing experimental results. However, the flexibility is defined according to the RSMT structure, failing to consider different circumstances of congestion distribution. In order to fix this flaw, we propose the new concept of Congestion-Oriented Flexibility. Further, we propose an effective algorithm to enhance the generalized flexibility. Finally, an RSMT Construction Algorithm based on Congestion-Oriented Flexibility is proposed, which is demonstrated to create a routing result with 12.1% less congestion than FLUTE [1] and congestion-driven Steiner trees [2].