Accuracy of simulation based on the acid-quencher mutual diffusion model in KrF processes

The accuracy of the acid-quencher mutual diffusion model was examined for three commercial resists (acetal-type resists for use with KrF exposure), by comparing results for real wafer CDs with simulated results as obtained by using the model with best-fit parameters (diffusion length for acid/quencher, and relative concentration of quencher). Utilizing our model reduced the deviation between simulated and measured CDs for a wide range of patterns to 6 nm in terms of standard deviation and +/- 10 nm in terms of p-v range. Best-fit Parameters are in the following ranges; acid-diffusion length equals 7 - 13 nm, quencher-diffusion length equals 150 - 200 nm, and relative quencher concentration equals 0.16 - 0.175 (all for two-iteration calculation). The best-fit diffusion length dependence on number of iterations in diffusion/quenching calculation implied agreement with Fick's law and the dependence of the best-fit relative quencher concentration on exposure dose suggested the validity of this model. Quencher diffusion into an organic bottom anti-reflective coating (BARC) was also observed by carrying out a simple experiment.