Patterning yield of sub-100-nm holes limited by fluctuation of exposure and development reactions

It is reported that reaction products (the stagnant layer) during development degrade the resist contrast, sensitivity, and process margin, and as a results, the reliability of fine patterning, and fluctuation of exposure reactions in projection lithography causes line edge roughness of resist patterns. These phenomena become more important as the size of patterns, especially holes, decreases down to the sub-100-nm level because the number of incident photons and the volume of exposed-resist-polymer for each pattern decrease dramatically. In this paper, we evaluate the patterning yield of sub-100-nm holes in SR lithography. Improvement of the yield for very fine patterns around the diffraction-limited resolution (50 nm) will be discussed.