Sub-50 nm period patterns with EUV interference lithography

We have used transmission diffraction gratings in an interferometric setup to pattern one- and two dimensional periodic patterns with periods near 50 nm. The diffraction gratings were written with e-beam lithography. The exposures were made at 13.4 nm wavelength with undulator radiation, which provides spatially coherent radiation. This technique offered a multiplication of pattern frequency by a factor of 2 and root2 in the one- and two-dimensional cases, respectively. Interference lithography with gratings offers a number of advantages, including achromaticity and insensitivity to misalignment. The demonstrated structures include line/space patterns with 45 nm period and a square array of holes with 56 nm period. (C) 2003 Elsevier Science B.V. All rights reserved.