The KrF excimer laser operating at 248 run is the light source of choice for the next generation of optical microlithography stepper systems. The key attributes of the excimer laser are its short wavelength and high degree of brightness compared with the mercury lamps now widely used. Due to the lack of achromatic lens systems at this short wavelength, the laser output must be linenarrowed and the center wavelength stabilized within tight tolerances. In this way the short wavelength can be reliably exploited to generate sub 0.5-μm features.

© 1989 Optical Society of America

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