Computational algorithms for optimizing mask layouts in proximity printing

We use numerical simulation and optimization algorithms to apply optical proximity correction (OPC) to different mask structures for exposure on a Mask Aligner in proximity mode. The range of OPC solutions reaches from subtle changes in the mask layout to masks that have lost almost all resemblance to the structure to be printed. An extreme case is the printing of periodic structures where we make use of the image reversal caused by the Talbot effect. We also show the improvement that can be obtained when co-optimizing the angular spectrum of the illumination, i.e. when performing a source-mask optimization (SMO).