Mask and source optimization for lithographic imaging systems

This paper proposes a new optimization procedure for mask and illumination geometries in optical projection lithography. A general merit function is introduced that evaluates the imaging performance of arbitrary line patterns over a certain focus range. It also takes into account certain technological aspects that are defined by the manufacturability and inspectability of the mask. Automatic optimization of the mask and illumination parameters with a genetic algorithm identifies optimum imaging conditions without any additional a-priori knowledge about lithographic processes. Several examples demonstrate the potential of the proposed concept.