Merits of Cellwise Model-Based OPC

One of the most compute intensive dataprep operations for 90nm PC level is the model-based optical proximity correction (MBOPC). The running time and output data size are growing unacceptably, particularly for ASICs and designs containing large macros built out of library cells (books). The reason for this growth is that the region-of-interest for MBOPC is approximately 600nm, which means that most library cells ”see” interactions with adjacent books in the same row and also in adjacent rows. In this paper, we investigate the merits of doing cellwise MBOPC. In its simplest form, the approach is to perform dataprep for each cell once per cell definition rather than once per placement. By inspection, this will reduce the computation time and output data size by a factor of P/D, where P is the number of book placements (100s to millions) and D is the number of book definitions. Our preliminary finding indicates that there is negligible difference between nominal CD for cellwise corrected cells and chipwise corrected cells. We will present our finding in terms of average CD and contact coverage, as well as runtime reduction.