A study of source and mask optimization for ArF scanners

The k1 factor continues to be driven downwards, in order to enable the 32 nm feature generation and beyond. Due to the extremely small process window that will be available for such demanding imaging challenges, it is necessary not only for each unit contributing to the imaging system to be driven to its ultimate performance capability, but also that active techniques that can expand the process window and robustness of the imaging against various kinds of imaging parameter be implemented. One such technique is a Source & Mask Optimization1 (SMO). In this paper we are going to study the effect of SMO and discuss its application to ArF exposure tools. Free form optimization example and constrained optimization will be compared with conventional illumination setting. Furthermore realization of the SMO with sPURE, which is optical element to generate customized illumination discussed.