Removal of contaminants by plasma assisted cleaning by metastable atom neutralization (PACMAN)

W. M. Lytle, D. S. Szybilski, C. E. Das, R. Raju, D. N. Ruzic

Research output: Chapter in Book/Report/Conference proceedingConference contribution


For the continued advancement of lithography, specifically extreme ultraviolet lithography (EUVL), particle contamination on the photomask and the subsequent removal of these particles is of critical importance. Particle contamination on the photomasks can result in defects printed on devices and their subsequent failure and/or process throughput reduction. A new idea for the removal of these particles is to utilize the energy in metastable species in a plasma. In a laboratory or processing plasma where ionization fraction is relatively low, there exists metastable species with long lifetimes that have significant energy, in some cases on the order of 20 eV. Through a combined process of ion bombardment as well as the energy transferred from the neutralization of the metastable species, particles on a surface can be reduced to volatile compounds which can be pumped off of the surface thus reducing the particle contamination on the surface. Preliminary results for the removal of polystyrene latex (PSL) nano particles on low resistivity silicon wafers have shown approximately 20 nm/min removal rates. The removal rate obtained through the use of the PACMAN technique is much faster compared to just metastable cleaning alone. The current results of the removal of particles via the PACMAN technique will be presented as well as a damage assessment if any caused by this process.

Original languageEnglish (US)
Title of host publicationAlternative Lithographic Technologies
StatePublished - Jun 19 2009
EventAlternative Lithographic Technologies - San Jose, CA, United States
Duration: Feb 24 2009Feb 26 2009

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherAlternative Lithographic Technologies
Country/TerritoryUnited States
CitySan Jose, CA


  • EUV
  • Electrostatics
  • Mask
  • Mask cleaning
  • Metastable cleaning

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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