Nanowire Grids Polarize Ultraviolet Light

The increased speed and power of microelectronic devices has come from a steady reduction in the size of their constituent features, which has been achieved by using progressively shorter wavelengths for the photolithography used in their fabrication. Today, the most advanced production photolithography uses 193 nm ultraviolet (UV) light from an ArF excimer laser. At such short wavelengths, polarization of the light becomes critical for achieving minimum feature size; obtaining s-polarized light at the wafer will be even more critical for the 193 nm immersion lithographic processes which are on the horizon. We have prepared square-centimeter metal nanowire grids which can polarize short-wavelength visible and ultraviolet light in transmission, much as classic Polaroid sheets will polarize longer-wavelength visible light. These grids are prepared from a shear-aligned block copolymer thin-film template, building on prior work from PCCM. We have also developed a model for their polarization characteristics, which reveals that the polarization of the transmitted light switches near the metal's plasma frequency.