Why are hydrogen ions best for MeV ion beam lithography?

Rattanaporn Norarat, Nitipon Puttaraksa, Mari Napari, A. R. Ananda Sagari, Mikko Laitinen, Timo Sajavaara, Peerapong Yotprayoonsak, Mika Pettersson, Orapin Chienthavorn, Harry J. Whitlow

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


The exposure characteristics of poly-(methyl methacrylate) (PMMA) for 2 MeV 1H +, 3 MeV 4He 2+ and 6 MeV 12C 3+ have been investigated. The samples were characterised using Atomic Force Microscopy (AFM), optical microscopy and Raman spectroscopy. Development was carried out using a 7:3 propan-2-ol:H 2O mixture to determine clearing and cross-linking fluences. It was found that protons had a considerably wider tolerance to exposure variations and a smaller span of doses within the ion track. Furthermore, the void formation and consequent stress-induced surface roughening were smaller for protons. For all ions, the CC bond Raman signal increased continuously with dose and fluence, even well above that required for total cross linking.

Original languageEnglish
Pages (from-to)22-24
Number of pages3
JournalMicroelectronic Engineering
Publication statusPublished - 2013 Feb
Externally publishedYes


  • AFM
  • Chain-scission
  • MeV ion beam lithography
  • PMMA
  • Raman spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering


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