title: Tunable two-mirror interference lithography system for wafer-scale nanopatterning.
abstract: We have designed and analyzed a novel (to the best of our knowledge) two-beam interference lithography system for large-area (wafer-level) nanopatterning with enhanced tunability of pattern periodicities. The tunable feature has been achieved by placing two rotational mirrors in the expanded beam paths at regulated angles for a desired period. Theoretical analyses show that the effective pattern coverage area greater than a 4 in. (10 cm) wafer scale is attainable with a 325 nm (30 cm coherence length) HeCd laser and 4 in. (10 cm) mirrors, while the pattern coverage area is restrained by the overruling effects between the optical coherence and mirror size. The experimental results also demonstrate uniform nanopatterns at varying periods (250-750 nm) on 4 in. (10 cm) substrates, validating the theoretical analyses. The tunable two-mirror interferometer will offer a convenient and robust way to prepare large-area nanostructures on a wafer scale with superior tunability in their pattern periodicities.
authors.affiliation: Department of Mechanical Engineering, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Mao
authors.forename: Ishan
authors.initials: I
authors.lastname: Wathuthanthri
authors.forename: Chang-Hwan
authors.initials: CH
authors.lastname: Choi