Optical EngineeringGeneralized characteristic model for lithography: application to negative chemically amplified resists
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A generalized approach to modeling resist performance is introduced and applied toward characterizing a negative chemically amplified resist system. The Generalized Characteristic Model for lithography is used to extract parameters to evaluate easily development rates from characteristic curves. The model suggests that two lumped parameters, αn and E0, dominate lithographic response for negative chemically amplified resists. Both αn and E0 were regressed from characteristic curves over a postexposure bake temperature and time range from 110 to 150°C and 30 to 90 s and develop times from 30 to 150 s. The parameter E0 showed the predicted postexposure bake temperature and time and develop time dependencies over the processing window, while αn did not. Possible explanations for this discrepancy are discussed. These parameters were used to simulate linewidths that were compared with experimental results. Linewidth predictions using parameters extracted with the generalized characteristic model agreed to within 15% of experimental results over the entire processing window.