However, to maintain a good performance in other lithographic metrics, such as feature DoF, PW, mask error enhancement factor (MEEF), image log slope (ILS), and SRAF print-through suppression, it is generally necessary to co-optimize the mask shapes and the orthoedge parameters under formulations that consider a broad range of image requirements besides the spread in focus. The lengths of the orthogonal edges and the edge segments that connect to them can be treated as parameters, and suitable cancelation of phase distortions throughout the neighborhood of each feature edge can then be established by adjusting these parameters using optimization methodologies such as source mask optimization (SMO). The “optimized orthoedge” simulated results in Fig. 2 show that optimized orthoedge sizing and placement on assisted pitches can achieve similar performances in DoF, ILS, and MEEF as is achieved with conventionally assisted masks (see, e.g., Fig. 3), but without compromising the alignment of best-focus positions. This strongly favorable tradeoff is typically achieved whenever orthoedges are inserted into extended assist features. Orthoedges on the main features constitute an additional (fine) blurring of the defined edge, whose print location must be carefully controlled. Assists, on the other hand, must not print, but otherwise their amplitude on-wafer does not need to be finely set. Hence crenellation of 1-D feature edges in assists entails fewer tradeoffs than in main features. With 2-D random logic, a sophisticated optimization strategy can balance the tradeoffs between different metrics, as is desirable when orthoedges are deployed in main features. For example, EMF-aware SMO optimization of hammerhead line terminations shows that the tradeoffs of interest have a somewhat complex and unintuitive dependence on the detailed , fragmentation of the hammerheads, as we have described in 8.