Degradation mechanism and materials for 157-nm pellicles

Cesar M Garza; Tom Bierschenk

doi:10.1117/12.533329

28 May 2004 Degradation mechanism and materials for 157-nm pellicles

Cesar M Garza, Tom Bierschenk

Proceedings Volume 5377, Optical Microlithography XVII; (2004) https://doi.org/10.1117/12.533329
Event: Microlithography 2004, 2004, Santa Clara, California, United States

Abstract

A great deal of resources has been invested by the semiconductor industry as a whole to make ready 157 nm as the next lithography technology node. Despite of all this effort serious infrastructure issues remain to be solved. Perhaps the first one is the availability of CaF₂, but a close second is a suitable soft-pellicle material. It has been previously reported that standard 193nm materials, like Teflon AF and Cytop, fail catastrophically upon exposure at 157nm radiation; and that their transmission is very poor to non-existent. In this paper we report data showing that these materials have higher transmission and lifetimes than previously thought. The physical lifetime of Cytop of nearly 500 J/cm² is remarkably high, although the transmission varies as a function dose suggesting physical and chemical changes from the onset. For Teflon AF the transmission is a more complex function of exposure dose, suggesting competing mechanisms. From experiments run with PVDF (polyvinyl difluoride), we conclude that the widely reported photodarkening effect is due to the presence of hydrogen in close proximity to a fluorine atom. From IR spectra we conclude that the dioxole moeity in Teflon AF undergoes a series of photochemical reactions that lead to the physical destruction of the polymer.

Citation Download Citation

Cesar M Garza and Tom Bierschenk "Degradation mechanism and materials for 157-nm pellicles", Proc. SPIE 5377, Optical Microlithography XVII, (28 May 2004); https://doi.org/10.1117/12.533329

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