Study of the impact of illumination intensity distribution on resist parameter modification

摘要

An Illumination intensity distribution of an exposure tool varies CD in simulation. In order to obtain reliable resist parameters, we studied the influence of the illumination intensity distribution in tuning the resist parameters and the accuracy of the simulation using the tuned resist parameters under different illumination conditions from in tuning. We tuned resist parameters with two models of illumination intensity to experimental FEM data. One model, "Nominal", was assumed to be uniform intensity and a nominal shape of an exposure tool. Another model, "Measured", was measured illumination intensity distribution with grating-pinhole mask. Under the same illumination condition to tuning, RMS of CD difference between experiment and simulation using "Measured" in tuning and simulation was 0.7nm smaller than that using "Nominal". But under the different illumination condition from tuning, RMS using "Measured" was 1.4 - 1.6nm smaller in total of 1D-pattern than that using "Nominal". In the specific pattern RMS using "Measured" was rather smaller than RMS using "Nominal". These results indicate that, in order to gain accurate simulation result, the accurate illumination intensity distributions is need in tuning and simulation. If using "Nominal" in tuning and in simulation, CD difference between experiment and simulation will enlarge in fine patterns.