Flare distance

How to determine flare magnitude, η ?• Find optimum dose at the center of a largearea that contains LS patterns at variouspattern densities:• Calculate η by fitting the dose data to thefollowing equation:DxD50Dose=1+η1+2ηxη FittingDose vs Pattern Density2.01.81.61.41.21.00.80.60.40.20.00 0.2 0.4 0.6 0.8 1pattern densityDx: Optimized dose for various densityD50: Optimized dose at 50% densityx : pattern densityη0.20.40.60.8Pattern density (%)Line width (nm)50 40 32110203040506070809099NOVACD pattern for evaluating η(each square is 100 μm-sq area)2008 International Symposium on Extreme Ultraviolet Lithography 11