Pellicle choice for 193-nm immersion lithography photomasks

An assessment of the mechanical performance of pellicles from different vendors was performed. Pellicle-induced distortions were experimentally measured and numerical simulations were run to predict what improvements were desirable. The experiments included mask registration measurements before and after pellicle mounting for three of the major pellicle suppliers, and adhesive gasket material properties characterization for previously untested samples. The finite element numerical simulations were verified via comparison to experimental data for pellicles with known frame bows, measured by the vendor. The models were extended to simulate the effect of the chucking of reticles in an exposure tool, as well as the various magnification correction schemes available in such tools. Results were compared to ITRS requirements to evaluate performances. This study enables the AMTC to give important feedback to pellicle suppliers and make proper recommendations to customers for future pellicle choices.