For 193-nm lithography,water proves to be a suitable immersion fluid.ArF immersion offers the potential to extend conventional optical lithography to the 45-nm node and potentially to the 32-nm node.Additionally,with existing lenses,the immersion option offers the potential to increase the focus window with 50% and more,depending on actual NA and feature type.In this paper we discuss the results on imaging and overlay obtained with immersion.Using a 0.75 NA ArF projection lens,we have built a proto-type immersion scanner using TWINSCANTM technology.First experimental data on imaging demonstrated a large gain of depth of focus (DoF),while maintaining image contrast at high scan speed.For first pilot production with immersion,a 0.85 NA ArF lens will be used.The resolution capabihties of this system will support 65 nm node semiconductor devices with a DOF significantly larger than 0.5 um.Early imaging data of such a system confirms a significant increase in focus window. For 193-nm lithography, water proves to be a suitable immersion fluid. ArF immersion offers the potential to extend conventional optical lithography to the 45-nm node and potentially to the 32-nm node. Additionally, with existing lenses, the immersion option offers the potential to increase the focus window with 50% and more, depending on actual NA and feature type. In this paper we discuss the results on imaging and overlay obtained with immersion. Using a 0.75 NA ArF projection lens, we have built a proto- type immersion scanner using TWINSCANTM technology. First experimental data on imaging demonstrated a large gain of depth of focus (DoF), while maintaining image contrast at high scan speed. For first pilot production with immersion, a 0.85 NA ArF lens will be used. resolution capabihties of this system will support 65 nm node semiconductor devices with a DOF significantly larger than 0.5 um. Early imaging data of such a system confirms a significant increase in focus window.