Comprehensive EUV lithography model

As EUV lithography nears pilot-line stage, photolithography modeling becomes increasingly important in order for engineers to build viable, production-worthy processes. In this paper, we present a comprehensive, calibrated lithography model that includes optical effects such as mask shadowing and flare, combined with a stochastic resist model that can predict effects such as line-edge roughness. The model was calibrated to CD versus pitch data with varying levels of flare, as well as dense lines with varying degrees of mask shadowing. We then use this model to investigate several issues critical to EUV. First, we investigate EUV photoresist technology: the impact of photoelectron-PAG exposure kinetics on photospeed, and then we examine the trade-off between LWR and photospeed by changing quencher loading in the photoresist model. Second, we compare the predicted process windows for dense lines as flare and lens aberrations are reduced from the levels in the current alpha tools to the levels expected in the beta tools. The observed interactions between optical improvements and resist LWR indicate that a comprehensive model is required to provide a realistic evaluation of a lithography process.