Light-coupling masks: An alternative, lensless approach to high-resolutionoptical contact lithography

We describe an approach to optical lithography using light-scattering conta ct masks with protruding elements that couple light into a photoresist. Thi s method differs from conventional contact lithography in two important way s. First, because portions of the light-coupling mask (LCM) are made from a polymer, intimate contact with the resist occurs over large areas without additional load. This contact is readily reversible, and causes no observab le damage or contamination of the LCM or substrate. Second, the structure f ormed by the protruding parts of the LCM in contact with the resist can def ine local optical modes that impart directionality to the light propagating through the LC-M and amplify its intensity. We provide an experimental rea lization and theoretical description of the method, demonstrating its use f or the formation of 100 nm features with light having a wavelength of 256 n m. (C) 1998 American Vacuum Society.