15 April 2011 Stochastic acid-based quenching in chemically amplified photoresists: a simulation study
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BACKGROUND: The stochastic nature of acid-base quenching in chemically amplified photoresists leads to variations in the resulting acid concentration during post-exposure bake, which leads to line-edge roughness (LER) of the resulting features. METHODS: Using a stochastic resist simulator, we predicted the mean and standard deviation of the acid concentration after post-exposure bake for an open-frame exposure and fit the results to empirical expressions. RESULTS: The mean acid concentration after quenching can be predicted using the reaction-limited rate equation and an effective rate constant. The effective quenching rate constant is predicted by an empirical expression. A second empirical expression for the standard deviation of the acid concentration matched the output of the PROLITH stochastic resist model to within a few percent CONCLUSIONS: Predicting the stochastic uncertainty in acid concentration during post-exposure bake for 193-nm and extreme ultraviolet resists allows optimization of resist processing and formulations, and may form the basis of a comprehensive LER model.
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Chris A. Mack, Chris A. Mack, John J. Biafore, John J. Biafore, Mark D. Smith, Mark D. Smith, } "Stochastic acid-based quenching in chemically amplified photoresists: a simulation study", Proc. SPIE 7972, Advances in Resist Materials and Processing Technology XXVIII, 79720V (15 April 2011); doi: 10.1117/12.879831; https://doi.org/10.1117/12.879831

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