Analysis of dissolution factor of line edge roughness formation in chemically amplified electron beam resist

Line edge roughness (LER) is a serious issue for the fine patterning in electron beam (EB) lithography. LER is formed as a consequence of the accumulation of stochastic events induced in resist materials. In this study, the dissolution factor a of LER formation was investigated. The lineand-space patterns of a highly resolving chemically amplified EB resist were analyzed using a Monte Carlo simulation. From the dependence of the relationship between the dissolution factor, exposure dose, and pitch on the initial standard deviation of the number of protected units per polymer molecule, the initial distribution of protected units was estimated to be random for the resist analyzed in this study. a/2 was estimated to be roughly 1.0-1.6. The fluctuation of the number of protected units +/- a sigma(p)/2 was considered to contribute to the LER formation, where sigma(p) is the standard deviation of the number of protected units per polymer molecule after postexposure baking. The resist performance is considered to be improved by decreasing the initial standard deviation of the number of protected units and/or the dissolution factor. (C) 2018 The Japan Society of Applied Physics