25 June 1999 Gas curtain for mitigating hydrocarbon contamination of EUV lithographic optical components
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Calculations were carried out to study the effectiveness of a gas curtain for mitigating contamination form hydrocarbon gases in extreme UV (EUV) lithography tools. The momentum, energy and mass transport in the curtain and surrounding regions were calculated using a 2D finite volume model of a lithography tool. Argon was used for the gas curtain. The results from the calculations quantify the relationship between the argon flow rate and the hydrocarbon partial pressure in the region of the optical elements. In general, the hydrocarbon partial pressure decreases as the mass transfer Peclet number, Pe equals Vh/D, increases, where V is the velocity of the argon, h is the thickness of the gas curtain and D is the mass diffusivity. An argon flow rate of 12.2 torr 1/s is required to reduce the hydrocarbon partial pressure from 10-7 to 10-10 torr in the specific lithography tool considered here. The EUV transmission in the tool with the gas curtain is 0.93. This is a large improvement over the 0.5 transmission that would result by using a solid filter to contain the hydrocarbon gas.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Michael P. Kanouff, Michael P. Kanouff, Avijit K. Ray-Chaudhuri, Avijit K. Ray-Chaudhuri, } "Gas curtain for mitigating hydrocarbon contamination of EUV lithographic optical components", Proc. SPIE 3676, Emerging Lithographic Technologies III, (25 June 1999); doi: 10.1117/12.351077; https://doi.org/10.1117/12.351077

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