Throughput of steppers with off-axis illuminators: analysis and experiments

As manufacturing critical dimensions continue to shrink towards 0.35 /spl mu/m, the exposure of IC critical levels requires increasingly effective techniques. Demand for such techniques facilitates acceptance of off-axis illumination as a way to better control the process window of 0.35 /spl mu/m design rule. We focus our attention on issues related to optimization of exposure related factors influencing stepper throughput. We analyzed exposure conditions of one critical level commonly encountered in a variety of IC design. First, we present the result of process modeling and optimization of the critical level exposure. We then review the results of extensive proof-of-principle work done in support of modeling.