Altering the radiation chemistry of electron-beam lithography with a reactive gas: A study of Teflon AF patterning under water vapor

Mansoor A. Sultan, Sarah K. Lami, Armin Ansary, Douglas R. Strachan, Joseph W. Brill, J. Todd Hastings

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Variable-pressure electron-beam lithography (VP-EBL) employs an ambient gas at subatmospheric pressure to reduce charging of insulating films and substrates during electron exposure. In this work, VP-EBL proves to be an efficient method for patterning a widely used, but challenging to process, fluoropolymer, Teflon AF. However, rather than solely mitigating charging, the ambient gas is found to alter the radiation chemistry of the exposure process. Specifically, irradiating Teflon AF under water vapor increases the dissolution rate of the exposed regions in non-fluorinated solvents and enables complete patterning in a positive tone process. When compared to conventional e-beam resists, the contrast (≈4), clearing dose (<700 μC cm-2), and resolution (≈40 nm half-pitch) of Teflon AF are adequate. However, these figures of merit are quite remarkable when the process is considered as a means for directly patterning a functional material with extremely low surface energy, dielectric constant, and refractive index. Intriguingly, VP-EBL of Teflon AF under water vapor also exhibits non-reciprocity, through dose-rate dependence, and exhibits anomalous proximity effects. Thus, the influence of the ambient gas on radiation chemistry must be considered for VP-EBL, and some of the resulting effects may offer significant benefits for patterning both functional and lithographic materials.

Original languageEnglish
Article number305301
JournalNanotechnology
Volume30
Issue number30
DOIs
StatePublished - May 1 2019

Bibliographical note

Publisher Copyright:
© 2019 IOP Publishing Ltd.

Keywords

  • Teflon AF
  • electron-beam lithography
  • fluoropolymers
  • radiation chemistry
  • variable-pressure electron-beam Lithography

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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