EXTENDIBILITY OF X-RAY-LITHOGRAPHY TO LESS-THAN-OR-EQUAL-TO-130 NM GROUND RULES IN COMPLEX INTEGRATED-CIRCUIT PATTERNS

Previous experimental and theoretical evidence indicates that x-ray li thography can be used to pattern less than or equal to 180 nm features . In order to be used in manufacturing, x-ray lithography of complex i ntegrated circuit patterns (i.e., dense two-dimensional patterns) need s to be demonstrated with a practical proximity gap. However, no large body of experimental evidence exists for the extendibility of x-ray l ithography for complex patterns with ground rules of less than or equa l to 130 nm at gaps of 10-20 mu m. Simulations of image formation and resist dissolution are shown to have good agreement with experimental results. These simulations are then used to predict exposure latitude and gap latitude for printing one-dimensional 75-125 nm patterns at 10 -15 mu m gaps. Simulations indicate that at least +/-10% exposure dose latitude will exist for simple patterns at these gaps, but significan t nested-to-isolated linewidth bias will exist. Gaps must be controlle d to +/-1 mu m for +/-10% dose latitude. More complex two-dimensional patterns have been shown to exhibit line end shortening [J. Maldonado, R. Dellaguardia, S. Hector, M. McCord, and L. Liebmann, J. Vac. Sci. Technol. B 13, 3094 (1995)] that simulations qualitatively indicate a rise in part due to image formation. Simple serifs on line ends may be needed to reduce line end shortening. (C) 1996 American Vacuum Societ y.