Imaging of 1-nm-thick films with 193-nm microscopy

We have implemented a reflected-light microscope operating in the deep ultraviolet at 193 nm. Many materials absorb strongly at this wavelength, providing greatly enhanced contrast compared with visible and near-ultraviolet microscopes. Polymer films as thin as 1 nm and SiO(2) films as thin as 3 nm have been imaged with this nonoptimized instrument. We have also calculated image contrast for several thin-film materials that are important in semiconductor processing, and we show that 193-nm light provides 60-485x better contrast than visible light (500 nm) and 4-95x better contrast than near-ultraviolet light (315 nm) for these materials.