After achieving the 45-nm process, today's semiconductor industry is nearing the 20-nm process and looking for techniques that would enable sub-22-nm-half-pitch line patterns. Following the continuous increase in exposure tool numerical aperture, researchers are pursuing reductions in exposure wavelengths. This effort had them look at extreme ultraviolet (EUV: 13.4 nm in wavelength) as an exposure light source. Unlike the numerical aperture engineering, change of a light source to EUV demands development of its related components, such as photoresist and optics. Until a reliable solution for EUV lithography is developed, EUV interference lithography (EUVIL) would not solely advance the lithographic technology but would also help to optimize photoresist materials for EUV.