DIET processes on ruthenium surfaces related to extreme ultraviolet lithography (EUVL)

B. V. Yakshinskiy, R. Wasielewski, E. Loginova*, M. N. Hedhili, T. E. Madey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The aim of this work is to provide insights into desorption induced by electronic transitions (DIET) processes that affect the reflectivity of ruthenium-capped Mo/Si multilayer mirrors working under EUVL (extreme ultraviolet lithography) operating conditions [high vacuum, and 13.5 nm (92 eV) photons]. Critical issues are associated with possible oxidation of the 2 nm thick Ru capping layer due to the inevitable background pressure of H2O, and carbon build up due to background hydrocarbons. In the present work, we discuss aspects of the radiation-induced surface chemistry of Ru irradiated by 100 eV electrons and 92 eV photons. The cross section for electron-stimulated desorption of oxygen from O-covered Ru is ∼6 × 10-19 cm2. Carbon accumulation several nm thick occurs on the Ru surface during electron irradiation in methyl methacrylate (MMA) vapor, a model background impurity hydrocarbon. Radiation damage by low-energy secondary electrons is believed to dominate over direct photoexcitation of adsorbates under EUVL conditions. The secondary electron yield from Ru varies strongly with photon energy, and is ∼0.02 electrons/photon at 92 eV.

Original languageEnglish (US)
Pages (from-to)3220-3224
Number of pages5
JournalSurface Science
Volume602
Issue number20
DOIs
StatePublished - Oct 15 2008
Externally publishedYes

Keywords

  • Electron-stimulated desorption
  • Electronic transitions

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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