Open NSO Modeling for DFM

With the development of 90-nm and 65-nm technology, a layout optimization relating to real defects has become a necessity for DFM (Design for Manufacturability). In order to optimize a layout, it is essential to extract the position of nets from the layout. The paper provides a novel NSO (Net Sensitivity for Opens) model of arbitrary defect and layout, which takes into account the critical area and the nets area as well as the size distribution of random defects. An algorithm of this model is also presented based on mathematical morphology. Some results of experiments show that the proposed model can give the position of nets in the layout and provide reliable foundation for reduction of the loss of yield.