Proceedings PaperExtending the Newtonian design form for ultra-high numerical aperture and immersion lithography
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Lithographers have used the Newtonian design form in small field micro-steppers for resist development for nearly a decade, spanning two wavelength generations and several increases in numerical aperture. New and useful design solutions continue to evolve from this design form for increasing the numerical aperture beyond 0.85 (dry). Introducing immersion fluids to increase the numerical aperture further has altered the aberration contributions, allowing for numerical apertures to increase beyond 1.2 (wet) for the same reduction ratio and field sizes without increasing element blank sizes. Practical solutions will be discussed that will allow continued research as resolution limits are further extended. Several dry and wet design solutions at both 193 and 157 nm wavelengths will be reviewed and their performance compared.