Imaging of 32-nm 1:1 lines and spaces using 193-nm immersion interference lithography with second-generation immersion fluids to achieve a numerical aperture of 1.5 and a k[sub 1] of 0.25

Water-based immersion lithography using ArF illumination is able to provide optical solutions as far as the 45-nm node, but is not able to achieve the 38- or 32-nm nodes as currently defined. Achieving these lithographic nodes will require new, higher refractive index fluids to re- place the water used in first-generation immersion systems. We have developed a number of such second-generation high-index fluids for im- mersion lithography at 193 nm. These highly transparent fluids have 193-nm indices up to 1.664. To understand the behavior and perfor- mance of different fluid classes, we use spectral index measurements to characterize the index dispersion, coupled with Urbach absorption edge analysis and Lorentz Oscillator modeling. Interference imaging printers have long been available, and they now have a new use: a rapid, cost- effective way to develop immersion lithography, particularly at extremely high resolutions. Although interference printers will never replace classi- cal lens-based lithography systems for semiconductor device production, they do offer a way to develop resist and fluid technology at a relatively low cost. Their simple image-forming format offers easy access to the basic physics of advanced imaging. Issues such as polarization of the image-forming light rays, fluid/resist interaction during exposure, topcoat film performance, and resist line edge roughness LER at extremely high resolutions, can all be readily studied. 32-nm 1:1 line/space L/S imaging is demonstrated using two of the second-generation fluids. These resolutions are well beyond current lens-based system capabili- ties. Results on the performance of various resists and topcoats are also reported for 32-nm L/S features. © 2005 Society of Photo-Optical Instrumentation