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1 January 2004 Theoretical analysis of 157-nm hard pellicle system purification via a cyclic purge/fill process
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Optical lithography with 157-nm light is expected to bridge the gap between 193-nm technology and next-generation lithography. One important practical difficulty facing the implementation of 157-nm technology is gas absorption of 157-nm light. The exposure process for 193-nm technology is carried out in an air environment, but oxygen gas and water vapor severely attenuate 157-nm radiation. However, 157-nm exposure can be carried out in a nitrogen environment, which can be achieved by purging. A challenging aspect of the nitrogen purging process is the evacuation of the volume delineated by the pellicle frame, and the 800-µm-thick hard pellicle plate, which can fracture when subjected to an excessive pressure difference. A technique for pellicle purification via a cyclic purging and filling process is investigated. A theoretical analysis of the gas flow and pressure variation in the system is presented. The maximum stress induced in the hard pellicle during the process is predicted using finite element modeling. The minimum time for purification without causing excessive stress in the pellicle plate is estimated for a nominal set of conditions. Finally, a parametric analysis of important geometric variables including the size and number of purging holes as well as the filter resistance is presented.
©(2004) Society of Photo-Optical Instrumentation Engineers (SPIE)
Gregory F. Nellis, Amr Y. Abdo, Roxann L. Engelstad, and Eric P. Cotte "Theoretical analysis of 157-nm hard pellicle system purification via a cyclic purge/fill process," Journal of Micro/Nanolithography, MEMS, and MOEMS 3(1), (1 January 2004).
Published: 1 January 2004


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