Use of perfluoro-n-alkanes in vacuum ultraviolet applications
AssigneeE. I. Du Pont de Nemours and Company
InventorsRoger Harquail French, Robert Clayton Wheland
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Abstract
This invention concerns liquid perfluoro-n-alkanes for use in applications demanding high transparency at UV wavelengths ranging from about 150 to 165 nm, especially 157 nm. Uses include optical couplants, optical cements, optical elements, optical inspection media for semiconductor wafers and devices, and most especially immersion photolithography at 157 nm exposure wavelength.
Claims12
A process comprising providing a surface, a light source emitting light in the wavelength range from 155 to 160 nm, and a perfluoro-n-alkane liquid disposed between said light source and said surface and causing said light source to illuminate at least a portion of said surface, such that at least a portion of said emitted light illuminating said surface is caused to be transmitted through said liquid, said liquid consisting essentially of perfluoro-n-pentane, perfluoro-n-hexane, or a mixture thereof.
Dependencies are inferred from the claim text.