Reducing extreme ultraviolet mask three-dimensional effects by alternative metal absorbers

Vicky Philipsen*, Kim Vu Luong, Laurent Souriau, Andreas Erdmann, Dongbo Xu, Peter Evanschitzky, Robbert W.E. Van De Kruijs, Arash Edrisi, Frank Scholze, Christian Laubis, Mathias Irmscher, Sandra Naasz, Christian Reuter, Eric Hendrickx

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

21 Citations (Scopus)

Abstract

Over the recent years, extreme ultraviolet (EUV) lithography has demonstrated the patterning of ever-shrinking feature sizes (enabling the N7 technology node and below), whereas the EUV mask has remained unaltered, using a 70-nm tantalum (Ta)-based absorber. This has led to experimentally observed mask three-dimensional (M3D) effects at the wafer level, which are induced by the interaction between the oblique incident EUV light and the patterned absorber with typical thickness values on the order of several wavelengths. We exploit the optical properties of the absorber material of the EUV mask as an M3D mitigation strategy. Using rigorous lithographic simulations, we screen potential single-element absorber materials for their optical properties and optimal thickness for minimum best focus variation through pitch at the wafer level. In addition, the M3D mitigation by absorber material is evaluated by process window comparison of foundry N5-specific logic clips. To validate the rigorous simulation predictions and test the processing feasibility of the alternative absorber materials, we have selected the candidate single elements nickel and cobalt for an experimental evaluation on wafer substrates. We present the film characterization as well as the first patterning tests of these single-element candidate absorber materials.

Original languageEnglish
Article number041002
Number of pages13
JournalJournal of micro/nanolithography, MEMS, and MOEMS
Volume16
Issue number4
DOIs
Publication statusPublished - 1 Oct 2017

Keywords

  • absorber characterization
  • extreme ultraviolet mask absorber
  • mask three-dimensional effects
  • rigorous mask three-dimensional lithography simulation

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