Sidewall profiles in thick resist with direct image lithography

David W. Inglis*, James White, Varun K. A. Sreenivasan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Maskless lithography is an increasingly popular method of micro-patterning in research settings. This technical note presents methods for controlling the feature size and sidewall profile of thick-resist features, when exposed using maskless direct imaging systems. Maskless lithographic systems use focussed, uncollimated light, and therefore do not naturally produce the vertical sidewalls that may be required for soft lithography and other secondary processes. We explore exposure dose energy, placement of the focal plane, and the use of multiple focal planes to optimize features in thick (~800 µm) SU-8 resist. We find that placing the image plane at the mid-height of the resist film produces structures with a good compromise of sidewall angle and feature sharpness. We also find that using multiple exposures at multiple heights can produce sidewall angles that are stable over a range of dose energies.

Original languageEnglish
Article number107001
Pages (from-to)1-6
Number of pages6
JournalJournal of Micromechanics and Microengineering
Volume31
Issue number10
DOIs
Publication statusPublished - Oct 2021

Keywords

  • SU-8
  • exposure
  • maskless lithography

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