Ant system based 3D fixed-outline floor planning

The three dimension integrated circuit (3D IC) can alleviate the interconnect issue in the nanoscale era, and is promising for heterogeneous integration. In this paper, we propose a two-phase method, combining ant system algorithm (AS) and simulated annealing to handle the 3D IC floorplanning with fixed-outline constraints. We propose a floorplan construction method for AS, where blocks are packed one by one, and the partitioned sequence pair is used to represent 3D IC floorplans. During the packing procedure, we have to make two decisions: (1) selecting a block to pack and (2) finding a proper position for the selected block in the constructed partial floorplan. The AS is used to explore the appropriate orders for packing blocks. When packing a block, the best position in the partial constructed floorplan will be selected. In the AS, we use the area of a block and the connection degree between blocks to represent the heuristic information, and also modify the pheromone update rule to adapt to the 3D IC floorplanning problem. The experimental results show the effectiveness of the proposed method.