Relationship between Stochastic Effect and Line Edge Roughness in Chemically Amplified Resists for Extreme Ultraviolet Lithography Studied by Monte Carlo Simulation

The fluctuation of the line edge of resist patterns, called line edge roughness (LER), has been the most serious problem in the development of next-generation lithography. The major root cause of LER is the chemical inhomogeneity at the boundary between the insoluble and soluble regions of the resist. In this study, the stochastic effect induced in the processes of formation of resist patterns was investigated using a Monte Carlo method. The relative standard deviation of acid concentration was smaller than that of absorbed photons. The relative standard deviation of protected units was smaller than that of acid concentration. By comparing the simulation results with the reported values of LER, it was found that the stochastic effect is further reduced in the development and rinse processes.

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