Low Cost Method for Generating Periodic Nanostructures by Interference Lithography Without the Use of an Anti-Reflection Coating

Omree Kapon, Merav Muallem, Alex Palatnik, Hagit Aviv, Yaakov R. Tischler

Research output: Contribution to journalArticlepeer-review

Abstract

Interference lithography has proven to be a useful technique for generating periodic sub-diffraction limited nanostructures. Interference lithography can be implemented by exposing a photoresist polymer to laser light using a two-beam arrangement or a one-beam configuration based on a Lloyd's Mirror Interferometer. For typical photoresist layers, an anti-reflection coating must be deposited on the substrate to prevent adverse reflections from cancelling the holographic pattern of the interfering beams. For silicon substrates, such coatings are typically multilayered and complex in composition. By thinning the photoresist layer to a thickness well below the quarter wavelength of the exposing beam, we demonstrate that interference gratings can be generated without an anti-reflection coating on the substrate. We used ammonium dichromate doped polyvinyl alcohol as the positive photoresist because it provides excellent pinhole free layers down to thicknesses of 40 nm, and can be cross-linked by a low-cost single mode 457 nm laser and etched in water. Gratings with a period of 320 nm and depth of 4 nm were realized, as well as a variety of morphologies depending on the photoresist thickness. This simplified interference lithography technique promises to be useful for generating periodic nanostructures with high fidelity and minimal substrate treatments.

Original languageEnglish
Pages (from-to)927-932
Number of pages6
JournalMRS Advances
Volume2
Issue number17
DOIs
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© 2017 Materials Research Society.

Keywords

  • Nanostructure
  • lithography (deposition)
  • polymer

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