Exact Combinatorial Optimization Methods for Physical Design of Regular Logic Bricks

As minimum feature sizes continue to scale down, increasing difficulties with subwavelength lithography have spurred research into more regular layout styles, such as restrictive design rules (RDRs) and regular logic fabrics. In this paper we show that the simplicity and discreteness of regular fabrics give rise to powerful exact combinatorial optimization methods for the brick layout problem (the regular fabric equivalent of the cell layout problem). These methods are either inapplicable or intractable for less regular layout styles, such as the DRC-based approach of standard cell layout. Results from our prototype tool demonstrate that these optimization methods are quite practical for bricks of typical size found in large-scale designs.