Extremely fine-pitch printing with a 10x Schwarzschild optic at extreme ultraviolet wavelengths

We demonstrate the use of a 13.4-nm wavelength, 10X-demagnification Schwarzschild optical system to expose high-resolution test patterns, extending well beyond the conventional resolution limit to dense feature sizes of 50 mn and below. We have successfully used a spatial frequency doubling technique to print equal line and space patterns with line widths as small as 30 mn. Simulations show that by using the fully extended numerical aperture, the system may achieve line widths as small as 12 nm. This configuration shows great potential for use in evaluating the ultimate performance and extendibility of resist materials for EUV lithography.