Cell-Based Hierarchical Pitchmatching Compaction Using Minimal LP

We describe a new linear programming (LP)-based hierarchical pitchmatching method. With a simplified treatment of the inter-cell constraints, the size of the LP problems is significantly smaller than the best known methods. In particular, the pitchmatching problem is decomposed into independent sub-problems by the natural slicing structure in layout. Each sub-problem is folded further to reduce the LP problem size. Experiments show that the LP problem size can be 10 times smaller than the best known result.