Development of an in-situ Sn cleaning method for extreme ultraviolet light lithography

J. Sporre, R. E. Lofgren, David N Ruzic, O. V. Khodykin, D. W. Myers

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


The development of a successful extreme ultraviolet light source for lithography relies on the ability to maintain collector optic cleanliness. Cleanliness is required to maintain the reflectivity of the collector optic, thus maintaining the light power output at the intermediate focus. In this paper, an in-situ method is explored to remove Sn from a contaminated collector optic. Hydrogen plasma is used to promote Sn etching while maintaining the integrity of the collector optic's multi-layer structure. The removal rate of Sn is investigated as a function of various operational parameters including chamber pressure, plasma electron density, as well as plasma electron temperature. Initial results are presented using an external RF-plasma source. The use of the collector optic as a RF-antenna is also investigated to optimize the etching rate of the hydrogen plasma. Initial plasma parameter measurements reveal electron densities on the order of 1011-1012 cm-3, with electron temperatures on the order of 1-3 eV. An optimized etch rate of ~125 nm/min off of Si was observed using 1000 W, 80 mTorr, and a flow rate of 50 sccm of H2. These initial measurements are used as a basis for optimizing the etching rate off of the collector optic. Such results are important in allowing the long-term usage of a single collector optic to minimize operating costs involved with replacing the optic as well as tool downtime.

Original languageEnglish (US)
Title of host publicationExtreme Ultraviolet (EUV) Lithography II
StatePublished - Jun 8 2011
EventExtreme Ultraviolet (EUV) Lithography II - San Jose, CA, United States
Duration: Feb 28 2011Mar 3 2011

Publication series

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


OtherExtreme Ultraviolet (EUV) Lithography II
Country/TerritoryUnited States
CitySan Jose, CA

ASJC Scopus subject areas

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


Dive into the research topics of 'Development of an in-situ Sn cleaning method for extreme ultraviolet light lithography'. Together they form a unique fingerprint.

Cite this