A high density placement algorithm based on simulated surface tension

The authors present a new approach to the placement problem of arbitrarily sized rectangles. The proposed final placement algorithm optimizes the compactness as well as the routability, which are, in general, conflicting requirements, depending on a weighting factor. The compaction behavior is created by assigning cohesion and adhesion forces to the cells and their surroundings, thus leading to a surface tension model. Optimization of routability is gained by using the result of a global placement step. Additional parameters are introduced to control the behavior of the algorithm. With a parameter optimizing strategy, the results of multiple final placement runs can be adapted to user-required properties as well as to the special characteristics of the placement problem itself. The approach has been implemented in an industrial layout system for multilayer PCBs (printed circuit boards) but can also be applied to multilayer VLSI layout based on macrocells